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Articles by Y Wang
Total Records ( 105 ) for Y Wang
  H Wang , Y Wang , L Sun and D. Liu
 

The 3' untranslated region (3' UTR) of eukaryotic mRNA is an important regulation element that affects not only mRNA translation, but also cell growth. We had found that the 3' UTR of CCAAT-enhancer-binding protein β (C/EBPβ) mRNA had tumor suppression activity. Herein, we reported that deletion of two short sequences at both termini of the C/EBPβ 3' UTR reduced the tumor suppression activity of this 3' UTR, as demonstrated by reduced cell growth, colony formation ability, and tumorigenicity in nude mice. It is noteworthy that the only deletion of a single such sequence was enough for the reduction of tumor suppression effect, and the reducing effect of deletion of the sequence near 3' terminus was stronger. Therefore, specific short sequences in the C/EBPβ 3' UTR are crucial for the tumor suppression activity of C/EBPβ.

  Y Yuan , J Tan , Y Wang , C Qian and M. Zhang
 

Chitosan (CS), a biocompatible and biodegradable material, can act as a non-viral delivery vehicle with low toxicity. In this study, plasmid DNA (pDNA) and siRNA were encapsulated in CS nanoparticles (NPs) to prepare CS–DNA and CS–siRNA NPs using a complex coacervation process. The CS–DNA particle size was within the range of 180–370 nm with a surface charge ranging from 0 to 18 mV at pH 5.5. The stability of pDNA in CS–DNA was investigated by pDNA release study and DNase I protection assay. The release of pDNA from NPs was studied in pH 7.4 phosphate-buffered saline at 37°C and the CS–DNA NPs could delay the DNA release. Results of DNase I protection assay showed that CS–DNA NPs could protect the encapsulated pDNA from nuclease degradation. In the transfection study, it was found that the transfection efficiency in vitro was dependent on the molecular weight, charge ratio, and DNA concentration of the CS–DNA NP as well as the type of cell transfected. Moreover, the morphology of HeLa cells transfected with CS–siRNA complexes was studied using atomic force microscopy. The results suggest that CS may be more capable than liposome in delivering siRNA to target cells. In summary, our analysis suggests that pDNA and siRNA can be encapsulated in CS NPs without being damaged.

  Y Wang , S Mao , B Li , P Tan , D Feng and J. Wen
 

Hepatitis C virus (HCV) infection is a leading cause of liver-related morbidity and mortality throughout the world. There is no vaccine available and current therapy is only partially effective. Since HCV infects only a minority of hepatocytes, we hypothesized that induction of apoptosis might be a promising approach for the treatment of hepatitis C. In the present study, recombinant caspase-3 gene (re-caspase-3) was used because it has the ability to induce apoptosis that is independent of the initiator caspases. An HCV-specific promoter is required to regulate the cytotoxic caspase-3 expression in HCV-infected cells. It has been reported that HCV core protein can specifically activate the 2',5'-oligoadenylate synthetase (OAS) gene promoter in human hepatocytes. Therefore, we constructed an expression vector consisting of the re-caspase-3 under the OAS gene promoter (pGL3-OAS-re-caspase-3) and then investigated its effect on HCV core-positive liver cells. It was found that the pGL3-OAS-re-caspase-3 construct induced apoptosis in HCV core-positive liver cells, but not in normal liver cells. These results strongly suggested that the transfer of the re-caspase-3 gene under the OAS promoter was a novel targeting approach for the treatment of HCV infection.

  Y Wang , F Meng and Y. Zhang
 

The low-molecular-weight protein tyrosine phosphatases (PTPase) exist ubiquitously in prokaryotes and eukaryotes and play important roles in the regulation of physiological activities. We report here the expression, purification and characterization of an active and soluble PTPase from Thermus thermophilus HB27 in Escherichia coli. This PTPase has an optimum pH range of 2.8–4.8 when using p-nitrophenyl phosphate as the substrate. The thermal inactivation results indicate a high thermal stability of this enzyme, with the optimum temperature of 75°C for activity. It can be activated by Mn2+, Mg2+, Ca2+, Ba2+, and Ni2+, but inhibited by Zn2+, Cu2+, Cl, and SO42–. These results suggest that this heat-resistant PTPase may play important roles in vivo in the adaptation of the microorganism to extreme temperatures and specific nutritional conditions.

  H Zhao , Y Wang , Y Wu , X Li , G Yang , X Ma , R Zhao and H. Liu
 

Hyperlipidemia is regarded as an independent risk factor in the development of ischemic heart disease, and it can increase the myocardial susceptibility to ischemia/reperfusion (I/R) injury. Ischemic postconditioning (Postcon) has been demonstrated to attenuate the myocardial injury induced by I/R in normal conditions. But the effect of ischemic Postcon on hyperlipidemic animals is unknown. Hypoxia inducible factor-1 (HIF-1) has been demonstrated to play a central role in the cardioprotection by preconditioning, which is one of the protective strategies except for Postcon. The aim of this study was to determine whether Postcon could reduce myocardial injury in hyperlipidemic animals and to assess whether HIF-1 was involved in Postcon mechanisms. Male Wistar rats underwent the left anterior descending coronary occlusion for 30 min followed by 180 min of reperfusion with or without Postcon after fed with high fat diet or normal diet for 8 weeks. The detrimental indices induced by the I/R insult included infarct size, plasma creatine kinase activity and caspase-3 activity. Results showed that hyperlipidemia remarkably enhanced the myocardial injury induced by I/R, while Postcon significantly decreased the myocardial injury in both normolipidemic and hyperlipidemic rats. Moreover, both hyperlipidemia and I/R promoted the HIF-1 expression. Most importantly, we have for the first time demonstrated that Postcon further induced a significant increase in HIF-1 protein level not only in normolipidemic but also in hyperlipidemic conditions. Thus, Postcon reduces the myocardial injury induced by I/R in normal and hyperlipidemic animals, and HIF-1 upregulation may involve in the Postcon-mediated cardioprotective mechanisms.

  X Jin , H Mei , X Li , Y Ma , A. h Zeng , Y Wang , X Lu , F Chu , Q Wu and J. Zhu
 

We studied the apoptosis-inducing properties of the antimicrobial peptide cecropin of Musca domestica in human hepatocellular carcinoma cell line BEL-7402 and its underlying mechanism. Proliferation inhibition of the human hepatocellular carcinoma BEL-7402 cells and the human normal liver cells were determined by the MTT assay, and the cell viability was determined by trypan blue dye exclusion assay. The apoptotic tumor cells treated with cecropin were examined by transmission electron microscopy and terminal-deoxynucleotidyl transferase mediated nick end labeling. The apoptosis rate was measured by flow cytometry (FCM) with PI/Annexin-V double staining. Western blot analysis and RT-PCR were used to determine the expression levels of proteins involved in apoptosis, such as Fas, Fas-L, caspase-8, and caspase-3. The experimental results showed that Musca domestica cecropin inhibited the proliferation of human hepatocellular carcinoma BEL-7402 cells in dose-dependent and time-dependent manners, without affecting the proliferation of normal liver cells. FCM showed that the cell apoptosis rates were 5.1 ± 0.11%, 8.1 ± 0.04%, and 10.9 ± 0.15% after the treating with 100 µM cecropin for 24, 48, and 72 h, respectively. The rates of apoptosis were 5.4 ± 0.14% and 8.0 ± 0.13% after the treating with 25 and 50 µM cecropin for 72 h, respectively. Western blot analysis and RT-PCR showed that the apoptosis-related molecules including Fas, Fas-L, caspase-8 and caspase-3 were activated. This study showed that the antimicrobial peptide cecropin-inducing apoptosis in human hepatocellular carcinoma BEL-7402 cells, which might be associated with upregulation of Fas, Fas-L, and caspase-8 and caspase-3 and triggering extrinsic apoptotic pathway.

  Y Wang , L Tao , Y Yuan , W. B Lau , R Li , B. L Lopez , T. A Christopher , R Tian and X. L. Ma
 

Adiponectin (APN) exerts its metabolic regulation largely through AMP-dependent protein kinase (AMPK). However, the role of AMPK in APN's antiapoptotic effect in ischemic-reperfused (I/R) adult cardiomyocytes remains incompletely understood. The present study was designed to determine the involvement of AMPK in the antiapoptotic signaling of APN. Cardiomyocytes from adult male mice overexpressing a dominant-negative 2-subunit of AMPK (AMPK-DN) or wild-type (WT) littermates were subjected to simulated I/R (SI/R) and pretreated with 2 µg/ml globular domain of APN (gAPN) or vehicle. SI/R-induced cardiomyocyte apoptosis was modestly increased in AMPK-DN cardiomyocytes (P < 0.05). Treatment with gAPN significantly reduced SI/R-induced apoptosis in WT cardiomyocytes as well as in AMPK-DN cardiomyocytes, indicating that the antiapoptotic effect of gAPN is partially AMPK independent. Furthermore, gAPN-induced endothelial nitric oxide synthase (eNOS) phosphorylation was significantly reduced in AMPK-DN cardiomyocytes, suggesting that the APN-eNOS signaling axis is impaired in AMPK-DN cardiomyocytes. Additional experiments demonstrated that treatment of AMPK-DN cardiomyocytes with gAPN reduced SI/R-induced NADPH oxidase overexpression, decreased superoxide generation, and blocked peroxynitrite formation to the same extent as that observed in WT cardiomyocytes. Collectively, our present study demonstrated that although the metabolic and eNOS activation effect of APN is largely mediated by AMPK, the superoxide-suppressing effect of APN is not mediated by AMPK, and this AMPK-independent antioxidant property of APN increased nitric oxide bioavailability and exerted significant antiapoptotic effect.

  Y Wang and X. Guan
 

Glucagon-like peptide-2 (GLP-2) is a neuropeptide secreted from endocrine cells in the gut and neurons in the brain. GLP-2 stimulates intestinal crypt cell proliferation and mucosal blood flow while decreasing gastric emptying and gut motility. However, a GLP-2-mediated signaling network has not been fully established in primary cells. Since the GLP-2 receptor mRNA and protein were highly expressed in the mouse hippocampus, we further characterized that human 125I-labeled GLP-21–33 specifically bound to cultured hippocampal neurons with Kd = 0.48 nM, and GLP-2 acutely induced subcellular translocalization of the early gene c-Fos. Using the whole cell patch clamp, we recorded barium currents (IBa) flowing through voltage-gated Ca2+ channels (VGCC) in those neurons in the presence of GLP-2 with and without inhibitors. We showed that GLP-2 (20 nM) enhanced the whole cell IBa mediated by L-type VGCC that was defined using an L-type Ca2+ channel blocker (nifedipine, 10 µM). Moreover, GLP-2-potentiation of L-type VGCC was abolished in neurons pretreated with a PKA inhibitor (PKI14–22, 1 µM). Finally, using a fluorescent nonmetabolized glucose analog (6-NBDG) tracing imaging, we showed that glucose was taken up directly by cultured neurons. GLP-2 increased 2-deoxy-d-[3H]glucose uptake that was dependent upon dosage, activation of PKA, and potentiation of L-type VGCC. We conclude that GLP-2 potentiates L-type VGCC activity through activating PKA signaling, partially stimulating glucose uptake by primary cultured hippocampal neurons. The potentiation of L-type VGCC may be physiologically relevant to GLP-2-induced neuroendocrine modulation of neurotransmitter release and hormone secretion.

  Y Wang , W. B Lau , E Gao , L Tao , Y Yuan , R Li , X Wang , W. J Koch and X. L. Ma
 

Adiponectin (APN) has traditionally been viewed as an adipocyte-specific endocrine molecule with cardioprotective effects. Recent studies suggest that APN is also expressed in cardiomyocytes. However, biological significances of this locally produced APN remain completely unknown. The aim of this study was to investigate the pathological and pharmacological significance of cardiac-derived APN in cardiomyocyte pathology. Adult cardiomyocytes from wild-type littermates (WT) or gene-deficient mice were pretreated with vehicle (V) or rosiglitazone (RSG) for 6 h followed by simulated ischemia-reperfusion (SI/R, 3 h/12 h). Compared with WT cardiomyocytes, myocytes from APN knockout (APN-KO) mice sustained greater SI/R injury, evidenced by greater oxidative/nitrative stress, caspase-3 activity, and lactate dehydrogenase (LDH) release (P < 0.05). Myocytes from adiponectin receptor 1 knockdown (AdipoR1-KD) or AdipoR1-KD/AdipoR2-KO mice had slightly increased SI/R injury, but the difference was not statistically significant. RSG significantly (P < 0.01) increased APN mRNA and protein expression, upregulated AdipoR1/AdipoR2 expression, reduced SI/R-induced apoptosis, and decreased LDH release in WT cardiomyocytes. However, the anti-oxidative/anti-nitrative and cell protective effects of RSG were completely lost in APN-KO cardiomyocytes (P > 0.05 vs. vehicle group), although a comparable degree of AdipoR1/AdipoR2 upregulation was observed. The upregulatory effect of RSG on APN mRNA and protein expression was significantly potentiated in AdipoR1-KD/AdipoR2-KO cardiomyocytes. However, the cellular protective effects of RSG were significantly blunted, although not completely lost, in these cells. These results demonstrated that cardiomyocyte APN is biologically active in protecting cells against SI/R injury. Moreover, this locally produced APN achieves its protective effect primarily through paracrine/autocrine activation of APN receptors.

  C Dasgupta , R Sakurai , Y Wang , P Guo , N Ambalavanan , J. S Torday and V. K. Rehan
 

Despite tremendous technological and therapeutic advances, bronchopulmonary dysplasia (BPD) remains a leading cause of respiratory morbidity in very low birth weight infants, and there are no effective preventive and/or therapeutic options. We have previously reported that hyperoxia-induced neonatal rat lung injury might be prevented by rosiglitazone (RGZ). Here, we characterize 1) perturbations in wingless/Int (Wnt) and transforming growth factor (TGF)-β signaling, and 2) structural aberrations in lung morphology following 7-day continuous in vivo hyperoxia exposure to neonatal rats. We also tested whether treatment of neonatal pups with RGZ, concomitant to hyperoxia, could prevent such aberrations. Our study revealed that hyperoxia caused significant upregulation of Wnt signaling protein markers lymphoid enhancer factor 1 (Lef-1) and β-catenin and TGF-β pathway transducers phosphorylated Smad3 and Smad7 proteins in whole rat lung extracts. These changes were also accompanied by upregulation of myogenic marker proteins -smooth muscle actin (-SMA) and calponin but significant downregulation of the lipogenic marker peroxisome proliferator-activated receptor- (PPAR) expression. These molecular perturbations were associated with reduction in alveolar septal thickness, radial alveolar count, and larger alveoli in the hyperoxia-exposed lung. These hyperoxia-induced molecular and morphological changes were prevented by systemic administration of RGZ, with lung sections appearing near normal. This is the first evidence that in vivo hyperoxia induces activation of both Wnt and TGF-β signal transduction pathways in lung and of its near complete prevention by RGZ. Hyperoxia-induced arrest in alveolar development, a hallmark of BPD, along with these molecular changes strongly implicates these proteins in hyperoxia-induced lung injury. Administration of PPAR agonists may thus be a potential strategy to attenuate hyperoxia-induced lung injury and subsequent BPD.

  B. R Weil , A. M Abarbanell , J. L Herrmann , Y Wang and D. R. Meldrum
  Optimizing the function and proliferative capacity of stem cells is essential to maximize their therapeutic benefits. High glucose concentrations are known to have detrimental effects on many cell types. We hypothesized that human mesenchymal stem cells (hMSCs) cultured in high glucose-containing media would exhibit diminished proliferation and attenuated production of VEGF, hepatocyte growth factor (HGF), and FGF2 in response to treatment with TNF-, LPS, or hypoxia. hMSCs were plated in medium containing low (5.5 mM) and high (20 mM or 30 mM) glucose concentrations and treated with TNF-, LPS, or hypoxia. Supernatants were collected at 24 and 48 h and assayed via ELISA for VEGF, HGF, and FGF2. In addition, hMSCs were cultured on 96-well plates at the above glucose concentrations, and proliferation at 48 h was determined via bromo-2'-deoxy-uridine (BrdU) incorporation. At 24 and 48 h, TNF-, LPS, and hypoxia-treated hMSCs produced significantly higher VEGF, HGF, and FGF2 compared with control. Hypoxia-induced VEGF production by hMSCs was the most pronounced change over baseline. At both 24 and 48 h, glucose concentration did not affect production of VEGF, HGF, or FGF2 by untreated hMSCs and those treated with TNF-, LPS, or hypoxia. Proliferation of hMSCs as determined via BrdU incorporation was unaffected by glucose concentration of the media. Contrary to what has been observed with other cells, hMSCs may be resistant to the short-term effects of high glucose. Ongoing efforts to characterize and optimize ex vivo and in vivo conditions are critical if the therapeutic benefits of MSCs are to be maximized.
  E Sibille , Y Wang , J Joeyen Waldorf , C Gaiteri , A Surget , S Oh , C Belzung , G. C Tseng and D. A. Lewis
 

OBJECTIVE: Major depressive disorder is a heterogeneous illness with a mostly uncharacterized pathology. Recent gene array attempts to identify the molecular underpinnings of the illness in human postmortem subjects have not yielded a consensus. The authors hypothesized that controlling several sources of clinical and technical variability and supporting their analysis with array results from a parallel study in the unpredictable chronic mild stress (UCMS) rodent model of depression would facilitate identification of the molecular pathology of major depression. METHOD: Large-scale gene expression was monitored in postmortem tissue from the anterior cingulate cortex and amygdala in paired male subjects with familial major depression and matched control subjects without major depression (N=14–16 pairs). Area dissections and analytical approaches were optimized. Results from the major depression group were compared with those from the UCMS study and confirmed by quantitative polymerase chain reaction and Western blot. Gene coexpression network analysis was performed on transcripts with conserved major depression-UCMS effects. RESULTS: Significant and bidirectional predictions of altered gene expression were identified in amygdala between major depression and the UCMS model of depression. These effects were detected at the group level and also identified a subgroup of depressed subjects with a more homogeneous molecular pathology. This phylogenetically conserved "molecular signature" of major depression was reversed by antidepressants in mice, identified two distinct oligodendrocyte and neuronal phenotypes, and participated in highly cohesive and interactive gene coexpression networks. CONCLUSIONS: These studies demonstrate that the biological liability to major depression is reflected in a persistent molecular pathology that affects the amygdala, and support the hypothesis of maladaptive changes in this brain region as a putative primary pathology in major depression.

  J. S Ross , D Madigan , K. P Hill , D. S Egilman , Y Wang and H. M. Krumholz
 

Background  In September 2004, rofecoxib was voluntarily withdrawn from the worldwide market. Our objective was to determine whether and when analysis of published and unpublished placebo-controlled trials could have revealed cardiovascular risk associated with rofecoxib before its withdrawal as an example to inform future postmarket pharmaceutical safety surveillance efforts.

Methods  We conducted a cumulative subject-level pooled analysis of data from all randomized, placebo-controlled trials of rofecoxib conducted by the manufacturer before September 2004. Our main outcome measurement was incidence of any investigator-reported death from any cause or cardiovascular thromboembolic (CVT) adverse event.

Results  We identified 30 randomized, placebo-controlled trials of rofecoxib that enrolled a combined 20 152 subjects. Trial duration ranged from 4 weeks to 4 years; enrollment ranged from 17 to 2586 subjects prescribed either rofecoxib or placebo; and rofecoxib dose ranged from 12.5 mg to 50 mg. As of December 2000, 21 of these trials had been completed (70%), and the risk of a CVT adverse event or death was greater among subjects assigned to the rofecoxib group (rate ratio [RR], 2.18; 95% confidence interval [CI], 0.93-5.81) (P = .07), raising concerns from a safety standpoint. Subsequently collected data through June 2001 showed that rofecoxib was associated with a 35% increased risk of a CVT adverse event or death (RR, 1.35; 95% CI, 1.00-1.96) (P = .05). Analyzing data available as of April 2002, we found a 39% increased risk (RR, 1.39; 95% CI, 1.07-1.80) (P = .02), and using data available as of September 2004, we found a 43% increased risk (RR,1.43; 95% CI, 1.16-1.76) (P < .001).

Conclusion  Cumulative pooled analysis of all randomized, placebo-controlled trials demonstrates a trend toward increased cardiovascular risk associated with rofecoxib compared with placebo as early as December 2000, the comparison reaching a P value of .05 by June 2001, nearly 31/2 years before the manufacturer's voluntary market withdrawal.

  M Zhang , N Congdon , L Li , Y Song , K Choi , Y Wang , Z Zhou , X Liu , A Sharma , W Chen and D. S. C. Lam
 

Objective  To study the effect of myopia and spectacle wear on bicycle-related injuries in rural Chinese students. Myopia is common among Chinese students but few studies have examined its effect on daily activities.

Methods  Data on visual acuity, refractive error, current spectacle wear, and history of bicycle use and accidents during the past 3 years were sought from 1891 students undergoing eye examinations in rural Guangdong province.

Results  Refractive and accident data were available for 1539 participants (81.3%), among whom the mean age was 14.6 years, 52.5% were girls, 26.8% wore glasses, and 12.9% had myopia of less than –4 diopters in both eyes. More than 90% relied on bicycles to get to school daily. A total of 2931 accidents were reported by 423 participants, with 68 requiring medical attention. Male sex (odds ratio, 1.55; P < .001) and spectacle wear (odds ratio, 1.38; P = .04) were associated with a higher risk of accident, but habitual visual acuity and myopia were unassociated with the crash risk, after adjusting for age, sex, time spent riding, and risky riding behaviors.

Conclusion  These results may be consistent with data on motor vehicle accidents implicating peripheral vision (potentially compromised by spectacle wear) more strongly than central visual acuity in mediating crash risk.

  J Kong , X Li , Y Wang , W Sun and J. Zhang
 

Objective  To assess the impact of digital problem-based learning (PBL) cases on student learning in ophthalmology courses.

Methods  Ninety students were randomly divided into 3 classes (30 students per class). The first class studied under a didactic model. The other 2 classes were divided into 6 groups (10 students per group) and received PBL teaching; 3 groups studied via cases presented in digital form and the others studied via paper-form cases. The results of theoretical and case analysis examinations were analyzed using the 2 test. Student performance on the interval practice was analyzed using the Kruskal-Wallis test. Questionnaires were used to evaluate student and facilitator perceptions.

Results  Students in the digital groups exhibited better performance in the practice procedures according to tutorial evaluations compared with the other groups (P < .05). The 2 PBL classes had significantly higher mean results of theoretical and case analysis examinations (P < .001), but there was no significant difference between the 2 PBL classes. Ninety-three percent of students in the digital groups (vs 73% in the paper groups) noted that the cases greatly stimulated their interest.

Conclusions  Introducing PBL into ophthalmology could improve educational quality and effectiveness. Digital PBL cases stimulate interest and motivate students to further improve diagnosis and problem-handling skills.

  A Stojadinovic , N Ahuja , S. M Nazarian , D. L Segev , L Jacobs , Y Wang , J Eberhardt and M. A. Zeiger
 

Objective  To review cutting-edge, novel, implemented and potential translational research and to provide a glimpse into rich, innovative, and brilliant approaches to everyday surgical problems.

Data Sources  Scientific literature and unpublished results.

Study Selection  Articles reviewed were chosen based on innovation and application to surgical diseases.

Data Extraction  Each section was written by a surgeon familiar with cutting-edge and novel research in their field of expertise and interest.

Data Synthesis  Articles that met criteria were summarized in the manuscript.

Conclusions  Multiple avenues have been used for the discovery of improved means of diagnosis, treatment, and overall management of patients with surgical diseases. These avenues have incorporated the use of genomics, electrical impedence, statistical and mathematical modeling, and immunology.

  Y Wang , R. I Sadreyev and N. V. Grishin
 

Sensitive and accurate detection of distant protein homology is essential for the studies of protein structure, function and evolution. We recently developed PROCAIN, a method that is based on sequence profile comparison and involves the analysis of four signals—similarities of residue content at the profile positions combined with three types of assisting information: sequence motifs, residue conservation and predicted secondary structure. Here we present the PROCAIN web server that allows the user to submit a query sequence or multiple sequence alignment and perform the search in a profile database of choice. The output is structured similar to that of BLAST, with the list of detected homologs sorted by E-value and followed by profile–profile alignments. The front page allows the user to adjust multiple options of input processing and output formatting, as well as search settings, including the relative weights assigned to the three types of assisting information.

  L Han , Y Wang and S. H. Bryant
 

This work provides an analysis of across-target bioactivity results in the screening data deposited in PubChem. Two alternative approaches for grouping-related targets are used to examine a compound's across-target bioactivity. This analysis identifies compounds that are selectively active against groups of protein targets that are identical or similar in sequence. This analysis also identifies compounds that are bioactive across unrelated targets. Statistical distributions of compound' across-target selectivity provide a survey to evaluate target specificity of compounds by deriving and analyzing bioactivity profile across a wide range of biological targets for tested small molecules in PubChem. This work enables one to select target specific inhibitors, identify promiscuous compounds and better understand the biological mechanisms of target-small molecule interactions.

  H Yi , X Yu , P Gao , Y Wang , S. H Baek , X Chen , H. L Kim , J. R Subjeck and X. Y. Wang
 

Class A scavenger receptor (SRA), also known as CD204, has been shown to participate in the pathogenesis of atherosclerosis and the pattern recognition of pathogen infection. However, its role in adaptive immune responses has not been well defined. In this study, we report that the lack of SRA/CD204 promotes Toll-like receptor (TLR)4 agonist–augmented tumor-protective immunity, which is associated with enhanced activation of CD8+ effector T cell and improved inhibition of tumor growth. Dendritic cells (DCs) deficient in SRA/CD204 display more effective immunostimulatory activities upon TLR4 engagement than those from wild-type counterparts. Silencing of SRA/CD204 by RNA interference improves the ability of DCs to prime antigen-specific CD8+ T cells, suggesting that antigen-presenting cells, for example, DCs, play a major role in SRA/CD204-mediated immune modulation. Our findings reveal a previously unrecognized role for SRA/CD204, a non-TLR pattern recognition receptor, as a physiologic negative regulator of TLR4-mediated immune consequences, which has important clinical implications for development of TLR-targeted immunotherapeutic intervention.

  F Simunovic , M Yi , Y Wang , L Macey , L. T Brown , A. M Krichevsky , S. L Andersen , R. M Stephens , F. M Benes and K. C. Sonntag
 

Parkinson's disease is caused by a progressive loss of the midbrain dopamine (DA) neurons in the substantia nigra pars compacta. Although the main cause of Parkinson's disease remains unknown, there is increasing evidence that it is a complex disorder caused by a combination of genetic and environmental factors, which affect key signalling pathways in substantia nigra DA neurons. Insights into pathogenesis of Parkinson's disease stem from in vitro and in vivo models and from postmortem analyses. Recent technological developments have added a new dimension to this research by determining gene expression profiles using high throughput microarray assays. However, many of the studies reported to date were based on whole midbrain dissections, which included cells other than DA neurons. Here, we have used laser microdissection to isolate single DA neurons from the substantia nigra pars compacta of controls and subjects with idiopathic Parkinson's disease matched for age and postmortem interval followed by microarrays to analyse gene expression profiling. Our data confirm a dysregulation of several functional groups of genes involved in the Parkinson's disease pathogenesis. In particular, we found prominent down-regulation of members of the PARK gene family and dysregulation of multiple genes associated with programmed cell death and survival. In addition, genes for neurotransmitter and ion channel receptors were also deregulated, supporting the view that alterations in electrical activity might influence DA neuron function. Our data provide a ‘molecular fingerprint identity’ of late–stage Parkinson's disease DA neurons that will advance our understanding of the molecular pathology of this disease.

  Y Wang , Z Zhang , J. R Garbow , D. J Rowland , R. A Lubet , D Sit , F Law and M. You
 

Antitumor B (ATB) is a Chinese herbal mixture of six plants. Previous studies have shown significant chemopreventive efficacy of ATB against human esophageal and lung cancers. We have recently developed a new mouse model for lung squamous cell carcinomas (SCC). In this study, lung SCC mouse model was characterized using small-animal imaging techniques (magnetic resonance imaging and computed tomography). ATB decreased lung SCC significantly (3.1-fold; P < 0.05) and increased lung hyperplastic lesions by 2.4-fold (P < 0.05). This observation suggests that ATB can block hyperplasia from progression to SCC. ATB tissue distribution was determined using matrine as a marker chemical. We found that ATB is rapidly absorbed and then distributes to various tissues including the lung. These results indicate that ATB is a potent chemopreventive agent against the development of mouse lung SCCs.

  Y Wang , W Wen , Y Yi , Z Zhang , R. A Lubet and M. You
 

In the present study, we examined the effect of bexarotene (Targretin) and budesonide in the chemoprevention of small cell lung carcinoma using a lung-specific knockout model of Rb1 and p53. Upon treatment with bexarotene, tumor incidence, number, and load were significantly reduced (P < 0.05). Budesonide treatment trended to inhibition, but the effect was not statistically significant (P > 0.05). Immunohistochemical staining indicated that bexarotene treatment decreased cell proliferation and increased apoptosis in tumors. The Rb1/p53 gene–targeted mouse seems to be a valuable model for chemopreventive studies on human small cell lung cancer. Our results indicate that the retinoid X receptor agonist bexarotene may be a potent chemopreventive agent in this cancer type.

  Z Cao , A Kozielski , X Liu , Y Wang , D Vardeman and B. Giovanella
 

To find a more effective and less toxic chemotherapeutic agent, we have successfully prepared crystalline camptothecin-20(S)-O-propionate hydrate (CZ48) by reacting camptothecin with propionic anhydride using concentrated sulfuric acid as catalyst. The biological effectiveness of this new anticancer agent was evaluated by using xenografts of human cancers in nude mice as the testing models. The extensive treatment of 21 human tumors with various dose levels of CZ48 has shown that this agent is highly effective against many different human tumors tested with a striking lack of toxicity. Of the 21 human tumor lines tested, 9 regressed, 5 were <10% of the control, 3 were <20%, and 2 were <40%. Two tumors did not respond. The total response rate was 90% (19 of 21). No toxicity was observed in mice. The effective doses required to achieve the positive response varied from 100 to 1,000 mg/kg/d depending on the tumors. The maximum tolerated dose was not reached because of the nontoxic nature of the drug in mice. Thus, this compound has a much wider therapeutic index compared with that of the existing anticancer drugs currently in use. [Cancer Res 2009;69(11):4742–9]

  Y Wang , J Li , Y Cui , T Li , K. M Ng , H Geng , H Li , X. s Shu , W Liu , B Luo , Q Zhang , T. S. K Mok , W Zheng , X Qiu , G Srivastava , J Yu , J. J.Y Sung , A. T.C Chan , D Ma , Q Tao and W. Han
 

Closely located at the tumor suppressor locus 16q22.1, CKLF-like MARVEL transmembrane domain-containing member 3 and 4 (CMTM3 and CMTM4) encode two CMTM family proteins, which link chemokines and the transmembrane-4 superfamily. In contrast to the broad expression of both CMTM3 and CMTM4 in normal human adult tissues, only CMTM3 is silenced or down-regulated in common carcinoma (gastric, breast, nasopharyngeal, esophageal, and colon) cell lines and primary tumors. CMTM3 methylation was not detected in normal epithelial cell lines and tissues, with weak methylation present in only 5 of 35 (14%) gastric cancer adjacent normal tissues. Furthermore, immunohistochemistry showed that CMTM3 protein was absent in 12 of 35 (34%) gastric and 1 of 2 colorectal tumors, which was well correlated with its methylation status. The silencing of CMTM3 is due to aberrant promoter CpG methylation that could be reversed by pharmacologic demethylation. Ectopic expression of CMTM3 strongly suppressed the colony formation of carcinoma cell lines. In addition, CMTM3 inhibited tumor cell growth and induced apoptosis with caspase-3 activation. Thus, CMTM3 exerts tumor-suppressive functions in tumor cells, with frequent epigenetic inactivation by promoter CpG methylation in common carcinomas. [Cancer Res 2009;69(12):5194–201]

  Y Adachi , R Li , H Yamamoto , Y Min , W Piao , Y Wang , A Imsumran , H Li , Y Arimura , C. T Lee , K Imai , D. P Carbone and Y. Shinomura
 

Insulin-like growth factor-I receptor (IGF-IR) signaling is required for carcinogenicity and proliferation of gastrointestinal (GI) cancers. We have previously shown significant therapeutic activity for recombinant adenoviruses expressing dominant-negative insulin-like growth factor-I receptor (IGF-IR/dn), including suppression of tumor invasion. In this study, we sought to evaluate the mechanism of inhibition of invasion and the relationship between IGF-IR and matrix metalloproteinase (MMP) activity in GI carcinomas. We analyzed the role of IGF-IR on invasion in three GI cancer cell lines, colorectal adenocarcinoma, HT29; pancreatic adenocarcinoma, BxPC3 and gastric adenocarcinoma, MKN45, using a modified Boyden chamber method and subcutaneous xenografts in nude mice. The impact of IGF-IR signaling on the expression of MMPs and the effects of blockade of matrilysin or IGF-IR on invasiveness were assessed using recombinant adenoviruses, a tyrosine kinase inhibitor NVP-AEW541 and antisense matrilysin. Invasive subcutaneous tumors expressed several MMPs. IGF-IR/dn reduced the expression of these MMPs but especially matrilysin (MMP-7). Insulin-like growth factor (IGF) stimulated secretion of matrilysin and IGF-IR/dn blocked IGF-mediated matrilysin induction in three GI cancers. Both IGF-IR/dn and inhibition of matrilysin reduced in vitro invasion to the same degree. NVP-AEW541 also reduced cancer cell invasion both in vitro and in murine xenograft tumors via suppression of matrilysin. Thus, blockade of IGF-IR is involved in the suppression of cancer cell invasion through downregulation of matrilysin. Strategies of targeting IGF-IR may have significant therapeutic utility to prevent invasion and progression of human GI carcinomas.

  X. L Xu , B. C Xing , H. B Han , W Zhao , M. H Hu , Z. L Xu , J. Y Li , Y Xie , J Gu , Y Wang and Z. Q. Zhang
 

Hepatocellular carcinoma (HCC) is associated with a high morbidity and mortality due to its high rate of recurrence. However, little is known about the biological characteristics of recurrent HCC cells. A single patient's primary and recurrent HCC-derived cell lines, Hep-11 and Hep-12, respectively, were established by primary culture. These two cell lines have the same hepatitis B virus integration site and share many common amplifications and deletions, which suggest that they have the same clonal origin. While Hep-11 cells were non-tumorigenic at 16 weeks following injection of up to 10 000 cells, injection of only 100 Hep-12 cells was sufficient to initiate tumor growth, and all single Hep-12 clones were tumorigenic in immunodeficient mice. Compared with Hep-11, Hep-12 cells expressed the oval cell markers AFP, NCAM/CD56, c-kit/CD117, as well as multiple stem cell markers such as Nanog, OCT4 and SOX2. In addition, >90% of Hep-12 cells were aldehyde dehydrogenase positive. They were also less resistant to paclitaxel, but more resistant to doxorubicin, cisplatin and hydroxycamptothecin (HCPT), which had been administrated to the patient. Furthermore, Hep-12 cells expressed higher levels of poly (adenosine diphosphate-ribose) polymerase-1 (PARP-1) than Hep-11, and PARP-1 inhibition potentiated the sensitivity to HCPT in Hep-12 cells but not in Hep-11 cells. These results indicate that a large population of the recurrent HCC-derived Hep-12 cells were tumor-initiating cells and that elevated expression of PARP-1 was related to their resistance to HCPT.

  Y Wang , P Broderick , A Matakidou , T Eisen and R. S. Houlston
 

Genome-wide association studies have provided evidence that common variation at 5p15.33 (TERT-CLPTM1L), 6p21.33 and 15q25.1 (CHRNA5-CHRNA3) influences lung cancer risk. To examine if variation at any of these loci influences the risk of lung cancer in never-smokers, we compared 5p15.33-TERT (rs2736100), 5p15.33-CLPTM1L (rs4975616), 6p21.33-BAT3 (rs3117582), 15q25.1-CHRNA3 (rs8042374) and 15q25.1-CHRNA3 (rs12914385) genotypes in a series of 239 never-smoker lung cancer cases and 553 never-smoker controls. A statistically significant association between lung cancer risk and 5p15.33 genotypes was found: rs2736100 (odds ratio = 0.78, 95% confidence interval: 0.63–0.97; P = 0.02), rs4975616 (odds ratio = 0.69, 95% confidence interval: 0.55–0.85; P = 7.95 x 10–4), primarily for adenocarcinoma. There was no evidence of association between 6p21.33 or 15q25.1 variation and risk of lung cancer. This analysis provides evidence that TERT-CLPTM1L variants may influence the risk of lung cancer outside the context of tobacco smoking.

  Y Wang , Y Huang , K. S.L Lam , Y Li , W. T Wong , H Ye , C. W Lau , P. M Vanhoutte and A. Xu
  Aims

Endothelial dysfunction is a key event that links obesity, diabetes, hypertension, and cardiovascular diseases. The aim of the present study was to examine the protective effect of the alkaloid drug berberine against hyperglycemia-induced cellular injury and endothelial dysfunction.

Methods and results

In both cultured endothelial cells and blood vessels isolated from rat aorta, berberine concentration dependently enhanced phosphorylation of endothelial nitric oxide synthase (eNOS) at Ser1177 and promoted the association of eNOS with heat shock protein 90 (HSP90), leading to an increased production of nitric oxide. Furthermore, berberine attenuated high glucose-induced generation of reactive oxygen species, cellular apoptosis, nuclear factor-B activation, and expression of adhesion molecules, thus suppressing monocyte attachment to endothelial cells. In mouse aortic rings, berberine elicited endothelium-dependent vasodilatations and alleviated high glucose-mediated endothelial dysfunction. All these beneficial effects of berberine on the endothelium were abolished by either pharmacological inhibition of adenosine monophosphate-activated protein kinase (AMPK) or adenovirus-mediated overexpression of a dominant negative version of AMPK.

Conclusion

Berberine protects against endothelial injury and enhances the endothelium-dependent vasodilatation, which is mediated in part through activation of the AMPK signalling cascade. Berberine or its derivatives may be useful for the treatment and/or prevention of endothelial dysfunction associated with diabetes and cardiovascular disease.

  T Chen , Z Huang , L Wang , Y Wang , F Wu , S Meng and C. Wang
  Aims

The inflammatory responses of monocytes/macrophages and the stimulation of lipid uptake into these cells by oxidized low density lipoprotein (oxLDL) are critical to the initiation and development of atherosclerosis. Increasing evidence has demonstrated that many microRNAs play important roles in the cell proliferation, apoptosis, and differentiation that accompany inflammatory responses. However, whether microRNAs are associated with monocyte/macrophage inflammatory responses or oxLDL stimulation is not yet known. The aim of the present study is to investigate microRNAs in monocytes/macrophages and their potential role in oxLDL-stimulation of lipid uptake and other atherosclerotic responses.

Methods and results

Microarrays were used to analyse the global expression of microRNAs in oxLDL-stimulated human primary peripheral blood monocytes. Expression profiles of the microRNAs were verified using TaqMan real-time PCR. Five microRNAs (microRNA-125a-5p, microRNA-9, microRNA-146a, microRNA-146b-5p, and microRNA-155) were aberrantly expressed after oxLDL treatment of human primary monocytes. Bioinformatics analysis suggested that microRNA-125a-5p is related to a protein similar to ORP9 (oxysterol binding protein-like 9) and this was confirmed by a luciferase reporter assay. MicroRNA-125a-5p was found to mediate lipid uptake and to decrease the secretion of some inflammatory cytokines (interleukin-2, interleukin-6, tumour necrosis factor-, transforming growth factor-beta) in oxLDL-stimulated monocyte-derived macrophages.

Conclusion

MicroRNA-125a-5p may partly provide post-transcriptional regulation of the proinflammatory response, lipid uptake, and expression of ORP9 in oxLDL-stimulated monocyte/macrophages.

  J Hirahashi , K Hishikawa , S Kaname , N Tsuboi , Y Wang , D. I Simon , G Stavrakis , T Shimosawa , L Xiao , Y Nagahama , K Suzuki , T Fujita and T. N. Mayadas
 

Background— Inflammation and thrombosis coexist in several disorders. Although it is recognized that leukocytes may induce a procoagulant state at sites of inflammation, the critical molecular determinants of this process remain largely unknown.

Methods and Results— To examine mechanisms of inflammation-induced thrombosis, we developed a murine model of thrombotic glomerulonephritis (TGN), a known cause of acute renal failure in patients. This model, induced by lipopolysaccharide and antibody to the glomerular basement membrane, led to rapid glomerular neutrophil recruitment, thrombotic glomerular lesions with endothelial cell injury, and renal dysfunction. In mice immunodepleted of neutrophils or lacking the leukocyte-specific integrin Mac-1, neutrophil recruitment, endothelial injury, glomerular thrombosis, and acute renal failure were markedly attenuated despite the robust generation of renal cytokines. Neutrophil elastase is a likely effector of Mac-1 because its activity was reduced in Mac-1–deficient mice and the phenotype in mice deficient in Mac-1 or neutrophil elastase was similar. Platelets accumulated in glomerular capillaries within 4 hours of TGN before evidence of thrombosis. Platelet immunodepletion before TGN markedly exacerbated hematuria (hemorrhage), inflammation, and injury, whereas thrombocytopenic Mac-1–deficient mice remained resistant to disease, indicating that initial glomerular platelet deposition protects the vessel wall from neutrophil-mediated sequelae. The subsequent thrombosis relied on the interaction of Mac-1 on recruited neutrophils with glycoprotein Ib on platelets as antibody-mediated disruption of this interaction attenuated TGN without affecting renal neutrophil accumulation.

Conclusions— These observations establish Mac-1 on neutrophils as a critical molecular link between inflammation and thrombosis and suggest it as an attractive target for antithrombotic therapy.

  M. C Tsai , L Chen , J Zhou , Z Tang , T. F Hsu , Y Wang , Y. T Shih , H. H Peng , N Wang , Y Guan , S Chien and J. J. Chiu
 

Rationale: Phenotypic modulation of smooth muscle cells (SMCs), which are located in close proximity to endothelial cells (ECs), is critical in regulating vascular function. The role of flow-induced shear stress in the modulation of SMC phenotype has not been well defined.

Objective: The objective was to elucidate the role of shear stress on ECs in modulating SMC phenotype and its underlying mechanism.

Methods and Results: Application of shear stress (12 dyn/cm2) to ECs cocultured with SMCs modulated SMC phenotype from synthetic to contractile state, with upregulation of contractile markers, downregulation of proinflammatory genes, and decreased percentage of cells in the synthetic phase. Treating SMCs with media from sheared ECs induced peroxisome proliferator-activated receptor (PPAR)-, -, and - ligand binding activities; transfecting SMCs with specific small interfering (si)RNAs of PPAR- and -, but not -, inhibited shear induction of contractile markers. ECs exposed to shear stress released prostacyclin (PGI2). Transfecting ECs with PGI2 synthase-specific siRNA inhibited shear-induced activation of PPAR-/, upregulation of contractile markers, downregulation of proinflammatory genes, and decrease in percentage of SMCs in synthetic phase. Mice with PPAR- deficiency (compared with control littermates) showed altered SMC phenotype toward a synthetic state, with increased arterial contractility in response to angiotensin II.

Conclusions: These results indicate that laminar shear stress induces synthetic-to-contractile phenotypic modulation in SMCs through the activation of PPAR-/ by the EC-released PGI2. Our findings provide insights into the mechanisms underlying the EC-SMC interplays and the protective homeostatic function of laminar shear stress in modulating SMC phenotype.

  S. C Kim , J. P Stice , L Chen , J. S Jung , S Gupta , Y Wang , G Baumgarten , J Trial and A. A. Knowlton
 

Rationale: Previously, we have found that changes in the location of intracellular heat shock protein (HSP)60 are associated with apoptosis. HSP60 has been reported to be a ligand of Toll-like receptor (TLR)-4.

Objective: We hypothesized that extracellular HSP60 (exHSP60) would mediate apoptosis via TLR4.

Methods and Results: Adult rat cardiac myocytes were treated with HSP60, either recombinant human or with HSP60 purified from the media of injured rat cardiac myocytes. ExHSP60 induced apoptosis in cardiac myocytes, as detected by increased caspase 3 activity and increased DNA fragmentation. Apoptosis could be reduced by blocking antibodies to TLR4 and by nuclear factor B binding decoys, but not completely inhibited, even though similar treatment blocked lipopolysaccharide-induced apoptosis. Three distinct controls showed no evidence for involvement of a ligand other than exHSP60 in the mediation of apoptosis.

Conclusions: This is the first report of HSP60-induced apoptosis via the TLRs. HSP60-mediated activation of TLR4 may be a mechanism of myocyte loss in heart failure, where HSP60 has been detected in the plasma.

  X Wang , W Xie , Y Zhang , P Lin , L Han , P Han , Y Wang , Z Chen , G Ji , M Zheng , N Weisleder , R. P Xiao , H Takeshima , J Ma and H. Cheng
 

Rationale: Unrepaired cardiomyocyte membrane injury causes irreplaceable cell loss, leading to myocardial fibrosis and eventually heart failure. However, the cellular and molecular mechanisms of cardiac membrane repair are largely unknown. MG53, a newly identified striated muscle-specific protein, is involved in skeletal muscle membrane repair. But the role of MG53 in the heart has not been determined.

Objective: We sought to investigate whether MG53 mediates membrane repair in cardiomyocytes and, if so, the cellular and molecular mechanism underlying MG53-mediated membrane repair in cardiomyocytes. Moreover, we determined possible cardioprotective effect of MG53-mediated membrane repair.

Methods and Results: We demonstrated that MG53 is crucial to the emergency membrane repair response in cardiomyocytes and protects the heart from stress-induced loss of cardiomyocytes. Disruption of the sarcolemmal membrane by mechanical, electric, chemical, or metabolic insults caused rapid and robust translocation of MG53 toward the injury sites. Ablation of MG53 prevented sarcolemmal resealing after infrared laser–induced membrane damage in intact heart, and exacerbated mitochondrial dysfunction and loss of cardiomyocytes during ischemia/reperfusion injury. Unexpectedly, the MG53-mediated cardiac membrane repair was mediated by a cholesterol-dependent mechanism: depletion of membrane cholesterol abolished, and its recovery restored injury-induced membrane translocation of MG53. The redox status of MG53 did not affect initiation of MG53 translocation, whereas MG53 oxidation conferred stability to the membrane repair patch.

Conclusions: Thus, cholesterol-dependent MG53-mediated membrane repair is a vital, heretofore unappreciated cardioprotective mechanism against a multitude of insults and may bear important therapeutic implications.

  J Cheng , Y Wang , Y Ma , B. T. y Chan , M Yang , A Liang , L Zhang , H Li and J. Du
  Rationale:

Mechanical stress plays an important role in proliferation of venous smooth muscle cells (SMCs) in neointima, a process of formation that contributes to failure of vein grafts. However, it is unknown what intracellular growth signal leads to proliferation of venous SMCs.

Objective:

The objective of this study is to identify mechanisms of mechanical stretch on neointima formation.

Methods and Results:

By a microarray analysis, we found that mechanical cyclic stretch (15% elongation) stimulated the transcription of SGK-1 (serum-, glucocorticoid-regulated kinase-1). Mechanical stretch–induced SGK-1 mRNA expression was blocked by actinomycin D. The mechanism for the SGK-1 expression involved MEK1 but not p38 or JNK signaling pathway. SGK-1 activation in response to stretch is blocked by insulin-like growth factor (IGF)-1 receptor inhibitor and mammalian target of rapamycin complex (mTORC)2 inhibitor (Ku-0063794) but not mTORC1 inhibitor (rapamycin). Mechanical stretch–induced bromodeoxyuridine incorporation was reduced by 83.5% in venous SMCs isolated from SGK-1 knockout mice. In contrast, inhibition of Akt, another downstream signal of PI3K resulted in only partial inhibition of mechanical stretch–induced proliferation of venous SMCs. Mechanical stretch also induced phosphorylation and nuclear exportation of p27kip1, whereas knockout of SGK-1 attenuated this effect of mechanical stretch on p27kip1. In vivo, we found that placement of a vein graft into artery increased SGK-1 expression. Knockout of SGK-1 effectively prevented neointima formation in vein graft. There is significant lower level of p27kip1 located in the nucleus of neointima cells in SGK-1 knockout mice compared with that of wild-type vein graft. In addition, we also found that wire injury of artery or growth factors in vitro increased expression of SGK-1.

Conclusions:

These results suggest that SGK-1 is an injury-responsive kinase that could mediate mechanical stretch–induced proliferation of vascular cells in vein graft, leading to neointima formation.

  K Beck , B. J Wu , J Ni , F. S Santiago , K. P Malabanan , C Li , Y Wang , L. M Khachigian and R. Stocker
  Rationale:

Induction of heme oxygenase (HO)-1 protects against experimental atherosclerotic diseases, and certain pharmacological HO-1 inducers, like probucol, inhibit the proliferation of vascular smooth muscle cells and, at the same time, promote the growth of endothelial cells in vivo and in vitro.

Objective:

Because such cell-specific effects are reminiscent of the action of the transcription factor Yin Yang (YY)1, we tested the hypothesis that there is a functional relationship between HO-1 and YY1.

Methods and Results:

We report that probucol increases the number of YY1+ cells in rat carotid artery following balloon injury at a time coinciding with increased HO-1 expression. The drug also induces the expression of YY1 mRNA and protein in rat aortic smooth muscle cells (RASMCs) in vitro, as do other known HO-1 inducers (tert-butylhydroquinone and hemin) and overexpression of HO-1 using a human HMOX1 cDNA plasmid. Conversely, overexpression of YY1 induces expression of HO-1 in RASMCs. Induction of YY1 expression is dependent on HO-1 enzyme activity and its reaction product CO, because pharmacological inhibition of heme oxygenase activity or CO scavenging block, whereas exposure of RASMCs to a CO-releasing molecule increases, YY1 expression. Furthermore, RNA interference knockdown of YY1 prevents probucol or adeno–HO-1 from inhibiting RASMC proliferation in vitro and neointimal formation in vivo.

Conclusions:

Our findings show, for the first time, that HO-1 functionally interplays with the multifunctional transcription factor YY1 and that this interplay explains some of the protective activities of HO-1.

  K Kawaji , N. C.F Codella , M. R Prince , C. W Chu , A Shakoor , T. M LaBounty , J. K Min , R. V Swaminathan , R. B Devereux , Y Wang and J. W. Weinsaft
 

Background— Cardiac magnetic resonance (CMR) is established for assessment of left ventricular (LV) systolic function but has not been widely used to assess diastolic function. This study tested performance of a novel CMR segmentation algorithm (LV-METRIC) for automated assessment of diastolic function.

Methods and Results— A total of 101 patients with normal LV systolic function underwent CMR and echocardiography (echo) within 7 days. LV-METRIC generated LV filling profiles via automated segmentation of contiguous short-axis images (204±39 images, 2:04±0:53 minutes). Diastolic function by CMR was assessed via early:atrial filling ratios, peak diastolic filling rate, time to peak filling rate, and a novel index—diastolic volume recovery (DVR), calculated as percent diastole required for recovery of 80% stroke volume. Using an echo standard, patients with versus without diastolic dysfunction had lower early:atrial filling ratios, longer time to peak filling rate, lower stroke volume–adjusted peak diastolic filling rate, and greater DVR (all P<0.05). Prevalence of abnormal CMR filling indices increased in relation to clinical symptoms classified by New York Heart Association functional class (P=0.04) or dyspnea (P=0.006). Among all parameters tested, DVR yielded optimal performance versus echo (area under the curve: 0.87±0.04, P<0.001). Using a 90% specificity cutoff, DVR yielded 74% sensitivity for diastolic dysfunction. In multivariate analysis, DVR (odds ratio, 1.82; 95% CI, 1.13 to 2.57; P=0.02) was independently associated with echo-evidenced diastolic dysfunction after controlling for age, hypertension, and LV mass (2=73.4, P<0.001).

Conclusions— Automated CMR segmentation can provide LV filling profiles that may offer insight into diastolic dysfunction. Patients with diastolic dysfunction have prolonged diastolic filling intervals, which are associated with echo-evidenced diastolic dysfunction independent of clinical and imaging variables.

  H. M Krumholz , A. R Merrill , E. M Schone , G. C Schreiner , J Chen , E. H Bradley , Y Wang , Z Lin , B. M Straube , M. T Rapp , S. L. T Normand and E. E. Drye
 

Background— In 2009, the Centers for Medicare & Medicaid Services is publicly reporting hospital-level risk-standardized 30-day mortality and readmission rates after acute myocardial infarction (AMI) and heart failure (HF). We provide patterns of hospital performance, based on these measures.

Methods and Results— We calculated the 30-day mortality and readmission rates for all Medicare fee-for-service beneficiaries ages 65 years or older with a primary diagnosis of AMI or HF, discharged between July 2005 and June 2008. We compared weighted risk-standardized mortality and readmission rates across Hospital Referral Regions and hospital structural characteristics. The median 30-day mortality rate was 16.6% for AMI (range, 10.9% to 24.9%; 25th to 75th percentile, 15.8% to 17.4%; 10th to 90th percentile, 14.7% to 18.4%) and 11.1% for HF (range, 6.6% to 19.8%; 25th to 75th percentile, 10.3% to 12.0%; 10th to 90th percentile, 9.4% to 13.1%). The median 30-day readmission rate was 19.9% for AMI (range, 15.3% to 29.4%; 25th to 75th percentile, 19.5% to 20.4%; 10th to 90th percentile, 18.8% to 21.1%) and 24.4% for HF (range, 15.9% to 34.4%; 25th to 75th percentile, 23.4% to 25.6%; 10th to 90th percentile, 22.3% to 27.0%). We observed geographic differences in performance across the country. Although there were some differences in average performance by hospital characteristics, there were high and low hospital performers among all types of hospitals.

Conclusions— In a recent 3-year period, 30-day risk-standardized mortality rates for AMI and HF varied among hospitals and across the country. The readmission rates were particularly high.

  G. K Mulvey , Y Wang , Z Lin , O. J Wang , J Chen , P. S Keenan , E. E Drye , S. S Rathore , S. L. T Normand and H. M. Krumholz
 

Background— The rankings of "America’s Best Hospitals" by U.S. News & World Report are influential, but the performance of ranked hospitals in caring for patients with routine cardiac conditions such as heart failure is not known.

Methods and Results— Using hierarchical regression models based on medical administrative data from the period July 1, 2005, to June 30, 2006, we calculated risk-standardized mortality rates and risk-standardized readmission rates for ranked and nonranked hospitals in the treatment of heart failure. The mortality analysis examined 14 813 patients in 50 ranked hospitals and 409 806 patients in 4761 nonranked hospitals. The readmission analysis included 16 641 patients in 50 ranked hospitals and 458 473 patients in 4627 nonranked hospitals. Mean 30-day risk-standardized mortality rates were lower in ranked versus nonranked hospitals (10.1% versus 11.2%, P<0.01), whereas mean 30-day risk-standardized readmission rates were no different between ranked and nonranked hospitals (23.6% versus 23.8%, P=0.40). The 30-day risk-standardized mortality rates varied widely for both ranked and nonranked hospitals, ranging from 7.9% to 12.4% for ranked hospitals and from 7.1% to 17.5% for nonranked hospitals. The 30-day risk-standardized readmission rates also spanned a large range, from 18.7% to 29.3% for ranked hospitals and from 19.2% to 29.8% for nonranked hospitals.

Conclusions— Hospitals ranked by U.S. News & World Report as "America’s Best Hospitals" in "Heart & Heart Surgery" are more likely than nonranked hospitals to have a significantly lower than expected 30-day mortality rate, but there was much overlap in performance. For readmission, the rates were similar in ranked and nonranked hospitals.

  D. T Ko , J. S Ross , Y Wang and H. M. Krumholz
 

Background— Cardiac catheterization is substantially underused among higher-risk patients with acute myocardial infarction (AMI) with appropriate indications but overused among patients with inappropriate indications. We sought to determine the importance of anticipated benefit and anticipated harm on the use of cardiac catheterization among older patients with AMI.

Methods and Results— We performed an analysis of Medicare fee-for-service beneficiaries hospitalized with an AMI between 1998 and 2001. Multivariate models were developed to determine relative importance of anticipated benefit (baseline cardiovascular risk), anticipated harm (bleeding risk, comorbidities), and demographic factors (age, sex, race, regional invasive intensity) in predicting cardiac catheterization use within 60 days of AMI admission. Analyses were stratified by American College of Cardiology/American Heart Association class I or II as appropriate, and class III as inappropriate. Determinants of reduced likelihood of cardiac catheterization among 42 241 AMI patients with appropriate indications included (in order of importance) older age (likelihood 2=1309.5), higher bleeding risk score (likelihood 2=471.2), more comorbidities (likelihood 2=276.6), female sex (likelihood 2=162.9), hospitalization in low (likelihood 2=67.9) or intermediate intensity invasive regions (likelihood 2=22.4) (all P<0.001), and baseline cardiovascular risk (likelihood 2=6.4, P=0.01). Among 2398 AMI patients with inappropriate indications, significant determinants of greater procedure likelihood included younger age, male sex, lower bleeding risk score, and fewer comorbidities.

Conclusions— Regardless of the procedure indication, the decision to perform cardiac catheterization in this population appears largely driven by demographic factors and potential harm rather than potential benefit of the procedure.

  K. J Lipska , Y Wang , M Kosiborod , F. A Masoudi , E. P Havranek , H. M Krumholz and S. E. Inzucchi
 

Background— Patients with diabetes are frequently admitted for acute myocardial infarction (AMI) on antihyperglycemic agents but may be discharged without glucose-lowering therapy. We examined the frequency of this practice and evaluated the associated outcomes of readmission and mortality.

Methods and Results— We conducted a retrospective study of 24 953 Medicare beneficiaries with diabetes discharged after hospitalization for AMI. We examined the frequency of discontinuation of antihyperglycemic agents on discharge among those patients admitted on a diabetic regimen. The independent association between discharge on versus off antihyperglycemic therapy and outcomes at 1 year was assessed in multivariable Cox proportional hazards models, adjusting for patient, physician, and hospital variables. The primary outcome was time to death within 1 year of discharge; secondary outcomes were time to first rehospitalization within 1 year for AMI, heart failure, and all causes. There were 8751 patients admitted on at least 1 antihyperglycemic agent who met our inclusion/exclusion criteria. Of these, 7581 (86.6%) were discharged on antihyperglycemic therapy and 1170 (13.4%) were discharged off antihyperglycemic therapy. After multivariable analysis, as compared with those whose diabetes therapy was continued at discharge, patients who were not prescribed a glucose-lowering agent had higher 1-year mortality rate (hazard ratio, 1.29; 95% confidence interval, 1.15 to 1.45). Readmission rates did not differ significantly between the 2 groups (hazard ratio, 0.95; 95% confidence interval, 0.87 to 1.03).

Conclusions— In older patients with diabetes after AMI, discontinuation of antihyperglycemic therapy is common and associated with higher mortality rates. The reasons behind this practice as well as the specific effects of hyperglycemia after AMI merit further study.

  S. M Bernheim , J. N Grady , Z Lin , Y Wang , S. V Savage , K. R Bhat , J. S Ross , M. M Desai , A. R Merrill , L. F Han , M. T Rapp , E. E Drye , S. L. T Normand and H. M. Krumholz
  Background—

Patient outcomes provide a critical perspective on quality of care. The Centers for Medicare and Medicaid Services (CMS) is publicly reporting hospital 30-day risk-standardized mortality rates (RSMRs) and risk-standardized readmission rates (RSRRs) for patients hospitalized with acute myocardial infarction (AMI) and heart failure (HF). We provide a national perspective on hospital performance for the 2010 release of these measures.

Methods and Results—

The hospital RSMRs and RSRRs are calculated from Medicare claims data for fee-for-service Medicare beneficiaries, 65 years or older, hospitalized with AMI or HF between July 1, 2006, and June 30, 2009. The rates are calculated using hierarchical logistic modeling to account for patient clustering, and are risk-adjusted for age, sex, and patient comorbidities. The median RSMR for AMI was 16.0% and for HF was 10.8%. Both measures had a wide range of hospital performance with an absolute 5.2% difference between hospitals in the 5th versus 95th percentile for AMI and 5.0% for HF. The median RSRR for AMI was 19.9% and for HF was 24.5% (3.9% range for 5th to 95th percentile for AMI, 6.7% for HF). Distinct regional patterns were evident for both measures and both conditions.

Conclusions—

High RSRRs persist for AMI and HF and clinically meaningful variation exists for RSMRs and RSRRs for both conditions. Our results suggest continued opportunities for improvement in patient outcomes for HF and AMI.

  T Suzuki , B. M Palmer , J James , Y Wang , Z Chen , P VanBuren , D. W Maughan , J Robbins and M. M. LeWinter
 

Background— The left ventricles of both rabbits and humans express predominantly β-myosin heavy chain (MHC). Transgenic (TG) rabbits expressing 40% -MHC are protected against tachycardia-induced cardiomyopathy, but the normal amount of -MHC expressed in humans is only 5% to 7% and its functional importance is questionable. This study was undertaken to identify a myofilament-based mechanism underlying tachycardia-induced cardiomyopathy protection and to extrapolate the impact of MHC isoform variation on myofilament function in human hearts.

Methods and Results— Papillary muscle strips from TG rabbits expressing 40% (TG40) and 15% -MHC (TG15) and from nontransgenic (NTG) controls expressing 100% β-MHC (NTG40 and NTG15) were demembranated and calcium activated. Myofilament tension and calcium sensitivity were similar in TGs and respective NTGs. Force-clamp measurements revealed 50% higher power production in TG40 versus NTG40 (P<0.001) and 20% higher power in TG15 versus NTG15 (P<0.05). A characteristic of acto-myosin crossbridge kinetics, the "dip" frequency, was significantly higher in TG40 versus NTG40 (0.70±0.04 versus 0.39±0.09 Hz, P<0.01) but not in TG15 versus NTG15. The calculated crossbridge time-on was also significantly shorter in TG40 (102.3±14.2 ms) versus NTG40 (175.7±19.7 ms) but not in TG15 versus NTG15.

Conclusions— The incorporation of 40% -MHC leads to greater myofilament power production and more rapid crossbridge cycling, which facilitate ejection and relengthening during short cycle intervals, and thus protect against tachycardia-induced cardiomyopathy. Our results suggest, however, that, even when compared with the virtual absence of -MHC in the failing heart, the 5% to 7% -MHC content of the normal human heart has little if any functional significance.

  J. S Ross , J Chen , Z Lin , H Bueno , J. P Curtis , P. S Keenan , S. L. T Normand , G Schreiner , J. A Spertus , M. T Vidan , Y Wang and H. M. Krumholz
 

Background— In July 2009, Medicare began publicly reporting hospitals’ risk-standardized 30-day all-cause readmission rates (RSRRs) among fee-for-service beneficiaries discharged after hospitalization for heart failure from all the US acute care nonfederal hospitals. No recent national trends in RSRRs have been reported, and it is not known whether hospital-specific performance is improving or variation in performance is decreasing.

Methods and Results— We used 2004–2006 Medicare administrative data to identify all fee-for-service beneficiaries admitted to a US acute care hospital for heart failure and discharged alive. We estimated mean annual RSRRs, a National Quality Forum-endorsed metric for quality, using 2-level hierarchical models that accounted for age, sex, and multiple comorbidities; variation in quality was estimated by the SD of the RSRRs. There were 570 996 distinct hospitalizations for heart failure in which the patient was discharged alive in 4728 hospitals in 2004, 544 550 in 4694 hospitals in 2005, and 501 234 in 4674 hospitals in 2006. Unadjusted 30-day all-cause readmission rates were virtually identical over this period: 23.0% in 2004, 23.3% in 2005, and 22.9% in 2006. The mean and SD of RSRRs were also similar: mean (SD) of 23.7% (1.3) in 2004, 23.9% (1.4) in 2005, and 23.8% (1.4) in 2006, suggesting similar hospital variation throughout the study period.

Conclusions— National mean and RSRR distributions among Medicare beneficiaries discharged after hospitalization for heart failure have not changed in recent years, indicating that there was neither improvement in hospital readmission rates nor in hospital variations in rates over this time period.

  S. L Hummel , N. P Pauli , H. M Krumholz , Y Wang , J Chen , S. L. T Normand and B. K. Nallamothu
 

Background— Heart transplant centers are generally considered "centers of excellence" for heart failure care. However, their overall performance has not previously been evaluated in a broad population of elderly patients with heart failure, many of whom are not transplant candidates.

Methods and Results— We identified >1 million elderly Medicare beneficiaries who were hospitalized for heart failure between 2004 and 2006 at >4500 hospitals. We calculated 30-day risk-standardized mortality rates and standardized mortality ratios as well as 30-day risk-standardized readmission rates and standardized readmission ratios at heart transplant centers and non–heart transplant hospitals using risk-standardization models that the Centers for Medicare & Medicaid Services uses for public reporting. The 30-day risk-standardized mortality rates were lower at heart transplant centers than non–heart transplant hospitals nationally (10.6% versus 11.5%, P<0.001) but were similar at peer institutions offering coronary artery bypass grafting within the same geographical region (10.6% versus 10.6%, P=0.96). The mean standardized mortality ratio for heart transplant centers was 0.9 (SD, 0.1; range, 0.7 to 1.3). No differences were noted in 30-day risk-standardized readmission rates between heart transplant centers and non–heart transplant hospitals nationally (23.6% versus 23.8%, P=0.55). The mean standardized readmission ratio for heart transplant centers was 1.0 (SD, 0.1; range, 0.8 to 1.2).

Conclusions— In elderly Medicare patients with heart failure, heart transplant centers have lower 30-day risk-standardized mortality rates than non–heart transplant hospitals nationally; however, this difference is not present in comparison with peer institutions or for 30-day risk-standardized readmission rates.

  Y Wang , C Qian , A. J.M Roks , D Westermann , S. M Schumacher , F Escher , R. G Schoemaker , T. L Reudelhuber , W. H van Gilst , H. P Schultheiss , C Tschope and T. Walther
 

Background— Angiotensin (Ang)-(1-7) attenuates the development of heart failure. In addition to its local effects on cardiovascular tissue, Ang-(1-7) also stimulates bone marrow, which harbors cells that might complement the therapeutic effect of Ang-(1-7). We studied the effects of Ang-(1-7) either produced locally in the heart or subcutaneously injected during the development of heart failure induced by myocardial infarction (MI) and explored the role of cardiovascular progenitor cells in promoting the effects of this heptapeptide.

Methods and Results— Effects of Ang-(1-7) on bone marrow–derived mononuclear cells in rodents, particularly endothelial progenitor cells, were investigated in vitro and in vivo in rats, in mice deficient for the putative Ang-(1-7) receptor Mas, and in mice overexpressing Ang-(1-7) exclusively in the heart. Three weeks after MI induction through permanent coronary artery occlusion, effects of Ang-(1-7) either produced locally in the heart or injected into the subcutaneous space were investigated. Ang-(1-7) stimulated proliferation of endothelial progenitor cells isolated from sham or infarcted rodents. The stimulation was blunted by A779, a Mas receptor blocker, or by Mas deficiency. Infusion of Ang-(1-7) after MI increased the number of c-kit– and vascular endothelial growth factor–positive cells in infarcted hearts, inhibited cardiac hypertrophy, and improved cardiac function 3 weeks after MI, whereas cardiomyocyte-derived Ang-(1-7) had no effect.

Conclusions— Our data suggest circulating rather than cardiac Ang-(1-7) to be beneficial after MI. This beneficial effect correlates with a stimulation of cardiac progenitor cells in vitro and in vivo. This characterizes the heptapeptide as a promising new tool in stimulating cardiovascular regeneration under pathophysiological conditions.

  W Wu , W Zhang , R Qiao , D Chen , H Wang , Y Wang , S Zhang , G Gao , A Gu , J Shen , J Qian , W Fan , L Jin , B Han and D. Lu
 

Purpose: Platinum agents cause DNA cross-linking and adducts. Xeroderma pigmentosum group D (XPD) plays a key role in the nucleotide excision repair pathway of DNA repair. Genetic polymorphisms of XPD may affect the capacity to remove the deleterious DNA lesions in normal tissues and lead to greater treatment-related toxicity. This study aimed to investigate the association of three polymorphisms of XPD at codons 156, 312, and 711, with the occurrence of grade 3 or 4 toxicity in advanced non–small cell lung cancer patients.

Experimental Design: We used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to genotype the three polymorphisms in 209 stage III and IV non–small cell lung cancer patients treated with platinum-based chemotherapy.

Results: The variant homozygotes of XPD p.Arg156Arg (rs238406) polymorphism were associated with a significantly increased risk of grade 3 or 4 hematologic toxicity (adjusted odds ratios, 3.24; 95% confidence interval, 1.35-7.78; P for trend = 0.009), and, more specifically, severe leukopenia toxicity (P for trend = 0.005). No statistically significant association was found for the three polymorphisms and grade 3 or 4 gastrointestinal toxicity. Consistent with these results of single-locus analysis, both the haplotype and the diplotype analyses revealed a protective effect of the haplotype "CG" (in the order of p.Arg156Arg-p.Asp312Asn) on the risk of grade 3 or 4 hematologic toxicity.

Conclusions: This investigation, for the first time, provides suggestive evidence of an effect of XPD p.Arg156Arg polymorphism on severe toxicity variability among platinum-treated non–small cell lung cancer patients.

  Y Zhang , Y Jia , R Zheng , Y Guo , Y Wang , H Guo , M Fei and S. Sun
  BACKGROUND:

The liver is frequently subject to insult because of viral infection, alcohol abuse, or toxic chemical exposure. Extensive research has been conducted to identify blood markers that can better discern liver damage, but little progress has been achieved in clinical practice. Recently, circulating microRNAs (miRNAs) have been reported as potential biomarkers for the noninvasive diagnosis of cancer. In this study, we investigated whether plasma miRNAs have diagnostic utility in identifying liver disease.

METHODS:

The study was divided into 2 phases: marker selection by real-time quantitative PCR analysis of a small set of plasma samples, and marker validation with a large set of plasma samples from 83 patients with chronic hepatitis B viral infections, 15 patients with skeletal muscle disease, and 40 healthy controls. Two mouse model systems, d-galactosamine- and alcohol-induced liver injury, were also developed to evaluate whether differences in miRNA concentration were associated with various liver diseases.

RESULTS:

Among the miRNA candidates identified, miR-122 presented a disease severity–dependent change in plasma concentration in the patients and animal models. Compared with an increase in aminotransferase activity in the blood, the change in miR-122 concentration appeared earlier. Furthermore, this change was more specific for liver injury than for other organ damage and was more reliable, because the change was correlated with liver histologic stage.

CONCLUSIONS:

Our findings suggest that circulating miR-122 has potential as a novel, predictive, and reliable blood marker for viral-, alcohol-, and chemical-induced liver injury.

  G Ramesh , C. D Krawczeski , J. G Woo , Y Wang and P. Devarajan
 

Background and objectives: Netrin-1, a laminin-related axon guidance molecule, is highly induced and excreted in the urine after acute kidney injury (AKI) in animals. Here, we determined the utility of urinary netrin-1 levels to predict AKI in humans undergoing cardiopulmonary bypass (CPB).

Design, setting, participants, & measurements: Serial urine samples were analyzed by enzyme-linked immunosorbent assay for netrin-1 in 26 patients who developed AKI (defined as a 50% or greater increase in serum creatinine after CPB) and 34 controls (patients who did not develop AKI after CPB).

Results: Using serum creatinine, AKI was detected on average only 48 hours after CPB. In contrast, urine netrin-1 increased at 2 hours after CPB, peaked at 6 hours (2462 ± 370 pg/mg creatinine), and remained elevated up to 48 hours after CPB. The predictive power of netrin-1 as demonstrated by area under the receiver-operating characteristics curve for diagnosis of AKI at 2, 6, and 12 hours after CPB was 0.74, 0.86, and 0.89, respectively. The 6-hour urine netrin-1 measurement strongly correlated with duration and severity of AKI, as well as length of hospital stay (all P < 0.05). Adjusting for CPB time, the 6-hour netrin-1 remained a powerful independent predictor of AKI, with an odds ratio of 1.20 (95% confidence interval: 1.08 to 1.41; P = 0.006).

Conclusion: Our results suggest that netrin-1 is an early, predictive biomarker of AKI after CPB and may allow for the reliable early diagnosis and prognosis of AKI after CPB, before the rise in serum creatinine.

  F. M. J Jacobs , A. J. A van der Linden , Y Wang , L von Oerthel , H. S Sul , J. P. H Burbach and M. P. Smidt
  Frank M. J. Jacobs, Annemarie J. A. van der Linden, Yuhui Wang, Lars von Oerthel, Hei Sook Sul, J. Peter H. Burbach, and Marten P. Smidt

The orphan nuclear receptor Nurr1 is essential for the development of meso-diencephalic dopamine (mdDA) neurons and is required, together with the homeobox transcription factor Pitx3, for the expression of genes involved in dopamine metabolism. In order to elucidate the molecular mechanisms that underlie the neuronal deficits in Nurr1-/- mice, we performed combined gene expression microarrays and ChIP-on-chip analysis and thereby identified Dlk1, Ptpru and Klhl1 as novel Nurr1 target genes in vivo. In line with the previously described cooperativity between Nurr1 and Pitx3, we show that the expression of Ptpru and Klhl1 in mdDA neurons is also dependent on Pitx3. Furthermore, we demonstrate that Nurr1 interacts with the Ptpru promoter directly and requires Pitx3 for full expression of Ptpru in mdDA neurons. By contrast, the expression of Dlk1 is maintained in Pitx3-/- embryos and is even expanded into the rostral part of the mdDA area, suggesting a unique position of Dlk1 in the Nurr1 and Pitx3 transcriptional cascades. Expression analysis in Dlk1-/- embryos reveals that Dlk1...

  Y Wang , W Feng , W Xue , Y Tan , D. W Hein , X. K Li and L. Cai
  OBJECTIVE

Glycogen synthase kinase (GSK)-3β plays an important role in cardiomyopathies. Cardiac-specific metallothionein-overexpressing transgenic (MT-TG) mice were highly resistant to diabetes-induced cardiomyopathy. Therefore, we investigated whether metallothionein cardiac protection against diabetes is mediated by inactivation of GSK-3β.

RESEARCH DESIGN AND METHODS

Diabetes was induced with streptozotocin in both MT-TG and wild-type mice. Changes of energy metabolism–related molecules, lipid accumulation, inflammation, nitrosative damage, and fibrotic remodeling were examined in the hearts of diabetic mice 2 weeks, 2 months, and 5 months after the onset of diabetes with Western blotting, RT-PCR, and immunohistochemical assays.

RESULTS

Activation (dephosphorylation) of GSK-3β was evidenced in the hearts of wild-type diabetic mice but not MT-TG diabetic mice. Correspondingly, cardiac glycogen synthase phosphorylation, hexokinase II, PPAR, and PGC-1 expression, which mediate glucose and lipid metabolisms, were significantly changed along with cardiac lipid accumulation, inflammation (TNF-, plasminogen activator inhibitor 1 [PAI-1], and intracellular adhesion molecule 1 [ICAM-1]), nitrosative damage (3-nitrotyrosin accumulation), and fibrosis in the wild-type diabetic mice. The above pathological changes were completely prevented either by cardiac metallothionein in the MT-TG diabetic mice or by inhibition of GSK-3β activity in the wild-type diabetic mice with a GSK-3β–specific inhibitor.

CONCLUSIONS

These results suggest that activation of GSK-3β plays a critical role in diabetes-related changes in cardiac energy metabolism, inflammation, nitrosative damage, and remodeling. Metallothionein inactivation of GSK-3β plays a critical role in preventing diabetic cardiomyopathy.

  T Dai , M Patel Chamberlin , R Natarajan , I Todorov , J Ma , J LaPage , L Phillips , C. C Nast , D Becerra , P Chuang , L Tong , J de Belleroche , D. J Wells , Y Wang and S. G. Adler
 

β-Cell apoptosis occurs in diabetes mellitus (DM). Heat shock protein (HSP) 27 (human homolog of rodent HSP25) mitigates stress-induced apoptosis but has not been studied in β-cells. We tested whether HSP27 overexpression attenuates streptozotocin (SZ)-induced DM in vivo and cytokine-induced islet apoptosis in vitro. DM was ascertained by ip glucose tolerance testing, and fasting serum insulin/glucose was measured. Pancreas was stained for insulin, HSP27, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, and insulin content was measured. HSP25/27 was measured by immunoblotting, isoelectric focusing, and RT-PCR. Islet HSP25/27 oligomerization and inhibitory B protein kinase (nuclear factor B essential modulator) binding were assessed by coimmunoprecipitation. HSP27 transgene (TG) in pancreas localized predominantly in β-cells. Baseline pancreatic insulin levels in wild-type (WT) and HSP27TG mice were similar, but lower in WT than HSP27TG after SZ (P < 0.01). Intraperitoneal glucose tolerance testing confirmed protection from SZ-DM in HSP27TG. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling and inducible nitric oxide synthase staining were increased in WT vs. HSP27TG islets (P < 0.05) after SZ. Caspase-3 activity was lower in islets from HSP27TG vs. WT mice after cytokine stress in vitro (P < 0.05). There was more HSP25 plus 27 protein from HSP27TG islets than HSP25 from WT (P < 0.01). HSP25 protein but not mRNA was increased in HSP27TG mice. Isoelectric focusing showed similar relative HSP phosphorylation in HSP27TG and WT (P > 0.05). HSP27 bound native HSP25 in TG islets; both bound to inhibitory B protein kinase (nuclear factor B essential modulator). These data show islet protection by HSP27 by mitigation of apoptosis, possibly through nuclear factor B regulation.

  P Olson , J Lu , H Zhang , A Shai , M. G Chun , Y Wang , S. K Libutti , E. K Nakakura , T. R Golub and D. Hanahan
 

While altered expression of microRNAs (miRs) in tumors has been well documented, it remains unclear how the miR transcriptome intersects neoplastic progression. By profiling the miR transcriptome we identified miR expression signatures associated with steps in tumorigenesis and the acquisition of hallmark capabilities in a prototypical mouse model of cancer. Metastases and a rare subset of primary tumors shared a distinct miR signature, implicating a discrete lineage for metastatic tumors. The miR-200 family is strongly down-regulated in metastases and met-like primary tumors, thereby relieving repression of the mesenchymal transcription factor Zeb1, which in turn suppresses E-cadherin. Treatment with a clinically approved angiogenesis inhibitor normalized angiogenic signature miRs in primary tumors, while altering expression of metastatic signature miRs similarly to liver metastases, suggesting their involvement in adaptive resistance to anti-angiogenic therapy via enhanced metastasis. Many of the miR changes associated with specific stages and hallmark capabilities in the mouse model are similarly altered in human tumors, including cognate pancreatic neuroendocrine tumors, implying a generality.

  H. K Liu , Y Wang , T Belz , D Bock , A Takacs , B Radlwimmer , S Barbus , G Reifenberger , P Lichter and G. Schutz
 

Malignant gliomas are the most common primary brain tumors, and are associated with frequent resistance to therapy as well as poor prognosis. Here we demonstrate that the nuclear receptor tailless (Tlx), which in the adult is expressed exclusively in astrocyte-like B cells of the subventricular zone, acts as a key regulator of neural stem cell (NSC) expansion and brain tumor initiation from NSCs. Overexpression of Tlx antagonizes age-dependent exhaustion of NSCs in mice and leads to migration of stem/progenitor cells from their natural niche. The increase of NSCs persists with age, and leads to efficient production of newborn neurons in aged brain tissues. These cells initiate the development of glioma-like lesions and gliomas. Glioma development is accelerated upon loss of the tumor suppressor p53. Tlx-induced NSC expansion and gliomagenesis are associated with increased angiogenesis, which allows for the migration and maintenance of brain tumor stem cells in the perivascular niche. We also demonstrate that Tlx transcripts are overexpressed in human primary glioblastomas in which Tlx expression is restricted to a subpopulation of nestin-positive perivascular tumor cells. Our study clearly demonstrates how NSCs contribute to brain tumorgenesis driven by a stem cell-specific transcription factor, thus providing novel insights into the histogenesis and molecular pathogenesis of primary brain tumors.

  R. S Srinivasan , X Geng , Y Yang , Y Wang , S Mukatira , M Studer , M. P. R Porto , O Lagutin and G. Oliver
 

The homeobox gene Prox1 is crucial for mammalian lymphatic vascular development. In the absence of Prox1, lymphatic endothelial cells (LECs) are not specified. The maintenance of LEC identity also requires the constant expression of Prox1. However, the mechanisms controlling the expression of this gene in LECs remain poorly understood. The SRY-related gene Sox18 is required to induce Prox1 expression in venous LEC progenitors. Although Sox18 is also expressed in embryonic arteries, these vessels do not express Prox1, nor do they give rise to LECs. This finding suggests that some venous endothelial cell-specific factor is required for the activation of Prox1. Here we demonstrate that the nuclear hormone receptor Coup-TFII is necessary for the activation of Prox1 in embryonic veins by directly binding a conserved DNA domain in the regulatory region of Prox1. In addition, we show that the direct interaction between nuclear hormone receptors and Prox1 is also necessary for the maintenance of Prox1 expression during early stages of LEC specification and differentiation.

  F Oury , V. K Yadav , Y Wang , B Zhou , X. S Liu , X. E Guo , L. H Tecott , G Schutz , A. R Means and G. Karsenty
 

Serotonin is a bioamine regulating bone mass accrual differently depending on its site of synthesis. It decreases accrual when synthesized in the gut, and increases it when synthesized in the brain. The signal transduction events elicited by gut-derived serotonin once it binds to the Htr1b receptor present on osteoblasts have been identified and culminate in cAMP response element-binding protein (CREB) regulation of osteoblast proliferation. In contrast, we do not know how brain-derived serotonin favors bone mass accrual following its binding to the Htr2c receptor on neurons of the hypothalamic ventromedial nucleus (VMH). We show here—through gene expression analysis, serotonin treatment of wild-type and Htr2c–/– hypothalamic explants, and cell-specific gene deletion in the mouse—that, following its binding to the Htr2c receptor on VMH neurons, serotonin uses a calmodulin kinase (CaMK)-dependent signaling cascade involving CaMKKβ and CaMKIV to decrease the sympathetic tone and increase bone mass accrual. We further show that the transcriptional mediator of these events is CREB, whose phosphorylation on Ser 133 is increased by CaMKIV following serotonin treatment of hypothalamic explants. A microarray experiment identified two genes necessary for optimum sympathetic activity whose expression is regulated by CREB. These results provide a molecular understanding of how serotonin signals in hypothalamic neurons to regulate bone mass accrual and identify CREB as a critical determinant of this function, although through different mechanisms depending on the cell type, neuron, or osteoblast in which it is expressed.

  M Guo , H Feng , J Zhang , W Wang , Y Wang , Y Li , C Gao , H Chen , Y Feng and Z. G. He
 

Sequence-specific DNA-binding transcription factors have widespread biological significance in the regulation of gene expression. However, in lower prokaryotes and eukaryotic metazoans, it is usually difficult to find transcription regulatory factors that recognize specific target promoters. To address this, we have developed in this study a new bacterial one-hybrid reporter vector system that provides a convenient and rapid strategy to determine the specific interaction between target DNA sequences and their transcription factors. Using this system, we have successfully determined the DNA-binding specificity of the transcription regulator Rv3133c to a previously reported promoter region of the gene Rv2031 in Mycobacterium tuberculosis. In addition, we have tested more than 20 promoter regions of M. tuberculosis genes using this approach to determine if they interact with ~150 putative regulatory proteins. A variety of transcription factors are found to participate in the regulation of stress response and fatty acid metabolism, both of which comprise the core of in vivo-induced genes when M. tuberculosis invades macrophages. Interestingly, among the many new discovered potential transcription factors, the WhiB-like transcriptional factor WhiB3 was identified for the first time to bind with the promoter sequences of most in vivo-induced genes. Therefore, this study offers important data in the dissection of the transcription regulations in M. tuberculosis, and the strategy should be applicable in the study of DNA-binding factors in a wide range of biological organisms.

  Y Wang , F Liska , C Gosele , L Sedova , V Kren , D Krenova , Z Ivics , N Hubner and Z. Izsvak
 

Endogenous retroviruses (ERVs) contribute to a range of germline, as well as somatic mutations in mammals. However, autonomous retrotransposition of potentially active elements has not been demonstrated in the rat genome. We cloned an insertion that disrupted the normal splicing of the Cntrob gene that was subsequently identified as a nonautonomous, novel endogenous retrovirus of the RnERV-K8e family. The RnERV-K8e family is closely related to the recently reported MmERV-K10c elements, but differs from the autonomous mouse MusD or IAP families. In addition, we identified a novel, unexpectedly close relative of RnERV-K8e in the mouse, suggesting ERV-K cross-species transmission between mice and rats. We cloned a potentially autonomous RnERV-K8e element identified by in silico analysis and, using an in vitro retrotransposition assay, demonstrated that it is capable of retrotransposition. This particular element (named Rat-, pronounced "retro") encodes a retroviral envelope gene (env); however, env is not required for de novo retrotransposition events. Significant levels of RnERV-K8e-associated genetic polymorphisms were detected among inbred rat strains, suggesting ongoing retrotransposition in the rat genome. This study identifies an ERV-K-type family in rats that shows obvious signs of recent activity. Ongoing retrotranspositional activity may significantly add to genomic variability among inbred rat strains.

  M Arabkhari , S Bunda , Y Wang , A Wang , A. V Pshezhetsky and A. Hinek
 

We recently established that the subunit of cell surface-residing elastin receptor, neuraminidase-1 (Neu1), can desialylate adjacent insulin-like growth factor 1 receptors (IGF-1R) of arterial smooth muscle cells, thereby quenching their proliferative response to insulin-like growth factor II. In this study, we explored whether Neu1 would also desialylate the insulin receptors (IR), as well as the IGF-1R on rat skeletal L6 myoblasts, and whether desialylation of IR and IGF-1R would affect a net proliferative effect of insulin. First, we found that physiological (0.5–1 nM) and high therapeutic (10 nM) insulin concentrations induced a modest increase in proliferation rate of cultured L6 myoblasts. While IR kinase inhibitor could abolish the mitogenic effect of these insulin concentrations, the observed more pronounced proliferative response to supraphysiological concentration (100 nM) of insulin could be eliminated only by specific inhibition of IGF-1R. Then, we found that treatment of L6 cells with mouse-derived Neu1 or with Clostridium perfringens neuraminidase caused desialylation of IR, which coincided with a significant increase of their proliferative response to lower (0.5–10 nM) concentrations of insulin. In contrast, experimental desialylation of IGF-1R coincided with elimination of the heightened proliferative response of L6 myoblasts to 100 nM insulin. Importantly, we also found that inhibition of endogenous Neu1 abolished the increase in proliferation of L6 cells induced by 1 and 10 nM of insulin, but amplified the proliferative effect of 100 nM insulin. We therefore conclude that desialylation of both IR and IGF-1R by Neu1 controls the net proliferative response of skeletal myoblasts to insulin.

  Y Liu , Y Wang , C Wu and P. Zheng
 

The majority of the Lafora's disease (LD) is caused by defect in the EPM2A gene, including missense and nonsense mutations and deletions. These defects mainly occur in the carbohydrate-binding domain, and how these mutations cause neuronal defects is under active investigation. Here, we report that the mutant proteins encoded by all missense mutations and most deletions tested are unstable, insoluble and ubiquitinated, and are accumulated in aggresome-like structures. The effect of apparent ‘gain-of-function’ mutations can be corrected by co-transfection of wild-type EPM2A cDNA, which is consistent with the recessive nature of these mutations in LD patients. In a neuronal cell line, these mutant aggregates exacerbate endoplasm reticulum (ER) stress and make the cells susceptible to the apoptosis induced by ER stressor, thapsigargin. The chemical chaperon, 4-phenylbutyrate, increased the mutant solubility, reduced the ER stress and dulled the sensitivity of mutant neuronal cells to apoptosis induced by thapsigargin and the mutant laforin proteins. The increased sensitivity to ER stress-induced apoptosis may contribute to LD pathogenesis.

  L Zhang , J Chen , Y Wang , F Ren , W Yu and L. Cheng
  BACKGROUND

Levonorgestrel (LNG), as a dedicated emergency contraception (EC) product, has been available over-the-counter in China for 10 years. Until now, only a small number of deliveries after LNG–EC failure have been documented.

METHODS

This study was a prospective comparative cohort study. A group of 332 pregnant women who had used LNG–EC during the conception cycle was recruited, and matched to a group of 332 pregnant women without the exposure to LNG. Congenital malformations, perinatal complications and delivery circumstances were investigated in this study.

RESULTS

There were 31 pregnant women in the study group and 28 in the comparison group miscarried within 14 weeks of gestation. In the study and comparison groups, four malformations were found in each group. In the study group, both birthweight (3416 versus 3345 g, P = 0.040) and the sex ratio of birth (boys/girls, 1.14 versus 0.90, P = 0.153) were higher than in the comparison group. There were no statistically significant differences in the incidence of miscarriage or malformation or in the neonatal outcome between the two groups.

CONCLUSIONS

There was no association between the use of LNG–EC pills and the risk of major congenital malformations, pregnancy complications or any other adverse pregnancy outcomes in our study.

  S Dharmaraja , Y Wang and G. Strang
 

The marginal stability of the trapezoidal method makes it dangerous to use for highly non-linear oscillations. Damping is provided by backward differences. The split-step combination (t trapezoidal, (1 – )t for BDF2) retains second-order accuracy. The ‘magic choice’ allows the same Jacobian for both steps, when Newton's method solves these implicit difference equations. That choice is known to give the smallest error constant, and we prove that also gives the largest region of linearized stability.

  X. S Wang , C. S Cleeland , T. R Mendoza , Y. H Yun , Y Wang , T Okuyama and V. E. Johnson
  Background

Patient reporting of the severity and impact of symptoms is an essential component of cancer symptom management and cancer treatment clinical trials. In multinational clinical trials, cultural and linguistic variations in patient-reported outcomes instruments could confound the interpretation of study results.

Methods

The severity and interference of multiple symptoms in 1433 cancer patients with mixed diagnoses and treatment status from the United States, China, Japan, Russia, and Korea were measured with psychometrically validated language versions of the M. D. Anderson Symptom Inventory (MDASI). Mixed-effect ordinal probit regression models were fitted to the pooled data to compare the magnitude of the effect of "country" (nation and linguistic factors) with between-subjects effects on symptom reporting, adjusted for patient and clinical factors (age, sex, performance status, and chemotherapy status).

Results

For the pooled sample, fatigue, disturbed sleep, distress, pain, and lack of appetite were the most severe patient-reported MDASI symptoms. The magnitude of the variance of the country random effects was only one-fourth to one-half of the interpatient variation (2 = 0.23–0.46) for all symptoms, except nausea and vomiting.

Conclusions

Cultural and linguistic variations in symptom reporting among the five language versions of the validated MDASI were limited. Ordinal probit modeling provided a simple mechanism for accounting for cultural and linguistic differences in patient populations. The equivalence among MDASI translations in this study suggests that symptom ratings collected from various cultural and language groups using the MDASI can be interpreted in a similar way in oncology practice, clinical trials, and clinical research.

  F. R Sattler , C Castaneda Sceppa , E. F Binder , E. T Schroeder , Y Wang , S Bhasin , M Kawakubo , Y Stewart , K. E Yarasheski , J Ulloor , P Colletti , R Roubenoff and S. P. Azen
 

Context: Impairments in the pituitary-gonadal axis with aging are associated with loss of muscle mass and function and accumulation of upper body fat.

Objectives: We tested the hypothesis that physiological supplementation with testosterone and GH together improves body composition and muscle performance in older men.

Design, Setting, and Participants: One hundred twenty-two community-dwelling men 70.8 ± 4.2 yr of age with body mass index of 27.4 ± 3.4 kg/m2, testosterone of 550 ng/dl or less, and IGF-I in lower adult tertile (≤167 ng/dl) were randomized to receive transdermal testosterone (5 or 10 g/d) during a Leydig cell clamp plus GH (0, 3, or 5 µg/kg · d) for 16 wk.

Main Outcome Measures: Body composition by dual-energy x-ray absorptiometry, muscle performance, and safety tests were conducted.

Results: Total lean body mass increased (1.0 ± 1.7 to 3.0 ± 2.2 kg) as did appendicular lean tissue (0.4 ± 1.4 to 1.5 ± 1.3 kg), whereas total fat mass decreased by 0.4 ± 0.9 to 2.3 ± 1.7 kg as did trunk fat (0.5 ± 0.9 to 1.5 ± 1.0 kg) across the six treatment groups and by dose levels for each parameter (P ≤ 0.0004 for linear trend). Composite maximum voluntary strength of upper and lower body muscles increased by 14 ± 34 to 35 ± 31% (P < 0.003 in the three highest dose groups) that correlated with changes in appendicular lean mass. Aerobic endurance increased in all six groups (average 96 ± 137sec longer). Systolic and diastolic blood pressure increased similarly in each group with mean increases of 12 ± 14 and 8 ± 8 mm Hg, respectively. Other predictable adverse events were modest and reversible.

Conclusions: Supplemental testosterone produced significant gains in total and appendicular lean mass, muscle strength, and aerobic endurance with significant reductions in whole-body and trunk fat. Outcomes appeared to be further enhanced with GH supplementation.

  T Tang , H Xie , Y Wang , B Lu and J. Liang
 

Rice grain filling is a process of conversion of sucrose into starch catalysed by a series of enzymes. Sucrose synthase (SUS) is considered as a key enzyme regulating this process. This study investigated the possible roles of sucrose and abscisic acid (ABA) in mediating the activity and expression of SUS protein of grains during grain filling in rice (Oryza sativa). Field-grown rice plants and detached cultured panicles were used as experimental materials. Several treatments, including spikelet thinning, leaf cutting, and applications of different concentrations of exogenous sucrose and ABA, were imposed during grain filling. A higher SUS activity was found in superior grains than in inferior grains in the earlier stage of grain filling, which was significantly and closely related to a higher grain filling rate and starch accumulation. An increase in sucrose concentration in grains as a result of different treatments increased both SUS activity and SUS protein expression in grains. An increase in ABA concentration gave similar results. Furthermore, effects of interactions between sucrose and ABA on the activity and expression of SUS protein in grains were also found. It was suggested that sucrose- and ABA-mediated rice grain filling is largely due to an increase in SUS activity and SUS protein expression.

  X Wang , W Song , Z Yang , Y Wang , Z Tang and C. Xu
 

The endosperm in plants is a major source of human nutrition and industrial raw material. The genetic study of endosperm poses a great challenge due to its complex genetic composition and unique physical and developmental properties. In this note, we shall revisit 2 classic mating designs—North Carolina Design III (NCIII) and triple test cross (TTC)—and demonstrate their efficiency in detecting quantitative trait loci underlying endosperm traits.

  Y Ling , Y Ma , W Guan , Y Cheng , Y Wang , J Han , D Jin , L Mang and H. Mahmut
 

Y chromosome acts as a single nonrecombining unit that is male specific and in effect haploid, thus ensuring the preservation of mutational events as a single haplotype via male lines. In this study, 6 Y chromosome–specific microsatellites (SSR) were tested for the patrilineal genetic variations of 573 male samples from Chinese domestic horse (30 breeds), Przewalski's horse, and donkey. All the 6 loci appeared as a haplotype block in Przewalski's horse and the domestic donkey. There were notable differences, however, at Y chromosome markers between horse and donkey. There were 2 haplotypes of Eca.YA16 in the domestic horse breeds, Haplotype A (Allele A: 156 bp) and Haplotype B (Allele B: 152 bp). Allele A was the common allele among 30 horse breeds, and Allele B was found in 11 horse breeds. This is the first description of a Y chromosome variant for horses. The 2 haplotypes of Y chromosome discovered in the domestic horse breeds in China could be helpful in unveiling their intricate genetic genealogy.

  L Lei , Y Xiong , J Chen , J. B Yang , Y Wang , X. Y Yang , C. C. Y Chang , B. L Song , T. Y Chang and B. L. Li
 

High levels of the inflammatory cytokine tumor necrosis factor- (TNF-) are present in atherosclerotic lesions. TNF- regulates expression of multiple genes involved in various stages of atherosclerosis, and it exhibits proatherosclerotic and antiatherosclerotic properties. ACAT catalyzes the formation of cholesteryl esters (CE) in monocytes/macrophages, and it promotes the foam cell formation at the early stage of atherosclerosis. We hypothesize that TNF- may be involved in regulating the ACAT gene expression in monocytes/macrophages. In this article, we show that in cultured, differentiating human monocytes, TNF- enhances the expression of the ACAT1 but not ACAT2 gene, increases the cholesteryl ester accumulation, and promotes the lipid-laden cell formation. Several other proinflammatory cytokines tested do not affect the ACAT1 gene expression. The stimulation effect is consistent with a receptor-dependent process, and is blocked by using nuclear factor-kappa B (NF-kappa B) inhibitors. A functional and unique NF-kappa B element located within the human ACAT1 gene proximal promoter is required to mediate the action of TNF-. Our data demonstrate that TNF-, through the NF-kappa B pathway, specifically enhances the expression of human ACAT1 gene to promote the CE-laden cell formation from the differentiating monocytes, and our data support the hypothesis that TNF- is proatherosclerotic during early phase of lesion development.

  Y Wang , M Zhang , C Moon , Q Hu , B Wang , G Martin , Z Sun and H. Wang
 

FE65 is expressed predominantly in the brain and interacts with the C-terminal domain of β-amyloid precursor protein (APP). We examined hippocampus-dependent memory and in vivo long-term potentiation (LTP) at the CA1 synapses with isoform-specific FE65 knockout (p97FE65–/–) mice. When examined using the Morris water maze, p97FE65–/– mice were impaired for the hidden platform task but showed normal performance in the probe test. To further discriminate the role of FE65 in acquisition and memory consolidation, we examined p97FE65–/– mice with temporal dissociative passive avoidance (TDPA) and contextual fear conditioning (CFC). p97FE65–/– mice showed impaired short-term memory for both TDPA and CFC when tested 10 min after training. After multiple TDPA training sessions, the crossover latency of some p97FE65–/– mice reached the cutoff value, but it significantly decayed in 8 d. At the Schaffer collateral-CA1 synapses, p97FE65–/– mice showed defective early-phase LTP (E-LTP). These results demonstrate novel roles of FE65 in synaptic plasticity, acquisition, and retention for certain forms of memory formation.

  A. L Bi , Y Wang , B. Q Li , Q. Q Wang , L Ma , H Yu , L Zhao and Z. Y. Chen
 

Actin rearrangement plays an essential role in learning and memory; however, the spatial and temporal regulation of actin dynamics in different phases of associative memory has not been fully understood. Here, using the conditioned taste aversion (CTA) paradigm, we investigated the region-specific involvement of actin rearrangement-related synaptic structure alterations in different memory processes. We found that CTA training could induce increased postsynaptic density (PSD) length in insular cortex (IC), but not in basolateral amygdala (BLA) and prelimbic cortex (PrL) during short-term memory (STM) formation, whereas it led to increased PSD length and synapse density in both IC and PrL during long-term memory (LTM) formation. Inhibition of actin rearrangement in the IC, but not in the BLA and PrL, impaired memory acquisition. Furthermore, actin dynamics in the IC or PrL is necessary for memory consolidation. On the contrary, inhibition of actin dynamics in the IC, BLA, or PrL had no effect on CTA memory retrieval. Our results suggest temporal and regional-specific regulation of actin rearrangement-related synaptic structure in different phases of CTA memory.

  S Li , Q Wang , Y Wang , X Chen and Z. Wang
 

It is well established that epidermal growth factor (EGF) induces the cytoskeleton reorganization and cell migration through two major signaling cascades: phospholipase C-1 (PLC-1) and Rho GTPases. However, little is known about the cross talk between PLC-1 and Rho GTPases. Here we showed that PLC-1 forms a complex with Rac1 in response to EGF. This interaction is direct and mediated by PLC-1 Src homology 3 (SH3) domain and Rac1 106PNTP109 motif. This interaction is critical for EGF-induced Rac1 activation in vivo, and PLC-1 SH3 domain is actually a potent and specific Rac1 guanine nucleotide exchange factor in vitro. We have also demonstrated that the interaction between PLC-1 SH3 domain and Rac1 play a significant role in EGF-induced F-actin formation and cell migration. We conclude that PLC-1 and Rac1 coregulate EGF-induced cell cytoskeleton remodeling and cell migration by a direct functional interaction.

  P Lamba , J Fortin , S Tran , Y Wang and D. J. Bernard
 

Selective synthesis and release of FSH from pituitary gonadotropes is regulated by activins. Activins directly stimulate murine FSHβ (Fshb) subunit gene transcription through a consensus 8-bp Sma- and Mad-related protein-binding element (SBE) in the proximal promoter. In contrast, the human FSHB promoter is relatively insensitive to the direct effects of activins and lacks this SBE. The proximal porcine Fshb promoter, which is highly conserved with human, similarly lacks the 8-bp SBE, but is nonetheless highly sensitive to activins. We used a comparative approach to determine mechanisms mediating differential activin induction of human, porcine, and murine Fshb/FSHB promoters. We mapped an activin response element in the proximal porcine promoter and identified interspecies variation in a single base pair in close proximity that conferred strong binding of the forkhead transcription factor FOXL2 to the porcine, but not human or murine, promoters. Introduction of the human base pair into the porcine promoter abolished FOXL2 binding and activin A induction. FOXL2 conferred activin A induction to the porcine promoter in heterologous cells, whereas knockdown of the endogenous protein in gonadotropes inhibited the activin A response. The murine Fshb promoter lacks the high-affinity FOXL2-binding site, but its activin induction is FOXL2 sensitive. We identified a more proximal FOXL2-binding element in the murine promoter, which is conserved across species. Mutation of this site attenuated activin A induction of both the porcine and murine promoters. Collectively, the data indicate a novel role for FOXL2 in activin A-regulated Fshb transcription.

  J Ai , Y Wang , J. A Dar , J Liu , L Liu , J. B Nelson and Z. Wang
 

The development of castration-resistant prostate cancer (PCa) requires that under castration conditions, the androgen receptor (AR) remains active and thus nuclear. Heat shock protein 90 (Hsp90) plays a key role in androgen-induced and -independent nuclear localization and activation of AR. Histone deacetylase 6 (HDAC6) is implicated, but has not been proven, in regulating AR activity via modulating Hsp90 acetylation. Here, we report that knockdown of HDAC6 in C4-2 cells using short hairpin RNA impaired ligand-independent nuclear localization of endogenous AR and inhibited PSA expression and cell growth in the absence or presence of dihydrotestosterone (DHT). The dose-response curve of DHT-stimulated C4-2 colony formation was shifted by shHDAC6 such that approximately 10-fold higher concentration of DHT is required, indicating a requirement for HDAC6 in AR hypersensitivity. HDAC6 knockdown also inhibited C4-2 xenograft tumor establishment in castrated, but not in testes-intact, nude mice. Studies using HDAC6-deficient mouse embryonic fibroblasts cells showed that inhibition of AR nuclear localization by HDAC6 knockdown can be largely alleviated by expressing a deacetylation mimic Hsp90 mutant. Taken together, our studies suggest that HDAC6 regulates AR hypersensitivity and nuclear localization, mainly via modulating HSP90 acetylation. Targeting HDAC6 alone or in combination with other therapeutic approaches is a promising new strategy for prevention and/or treatment of castration-resistant PCa.

  S Eleswarapu , X Ge , Y Wang , J Yu and H. Jiang
 

IGF-I is abundantly expressed in the liver under the stimulation of GH. We showed previously that expression of hepatocyte nuclear factor (HNF)-3, a liver-enriched transcription factor, was strongly stimulated by GH in bovine liver. In this study, we determined whether GH-increased HNF-3 might contribute to GH stimulation of IGF-I gene expression in bovine liver and the underlying mechanism. A sequence analysis of the bovine IGF-I promoter revealed three putative HNF-3 binding sites, which all appear to be conserved in mammals. Chromatin immunoprecipitation assays showed that GH injection increased binding of HNF-3 to the IGF-I promoter in bovine liver. Gel-shift assays indicated that one of the three putative HNF-3 binding sites, HNF-3 binding site 1, bound to the HNF-3 protein from bovine liver with high affinity. Cotransfection analyses demonstrated that this HNF-3 binding site was essential for the transcriptional response of the IGF-I promoter to HNF-3 in CHO cells and to GH in primary mouse hepatocytes. Using similar approaches, we found that GH increased binding of the signal transducer and activator of transcription 5 (STAT5) to the HNF-3 promoter in bovine liver, that this binding occurred at a conserved STAT5 binding site, and that this STAT5 binding site was necessary for the HNF-3 promoter to respond to GH. Taken together, these results suggest that in addition to direct action, GH-activated STAT5 may also indirectly stimulate IGF-I gene transcription in the liver by directly enhancing the expression of the HNF-3 gene.

  Z Meng , Y Wang , L Wang , W Jin , N Liu , H Pan , L Liu , L Wagman , B. M Forman and W. Huang
 

Liver repair is key to resuming homeostasis and preventing fibrogenesis as well as other liver diseases. Farnesoid X receptor (FXR, NR1H4) is an emerging liver metabolic regulator and cell protector. Here we show that FXR is essential to promote liver repair after carbon tetrachloride (CCl4)-induced injury. Expression of hepatic FXR in wild-type mice was strongly suppressed by CCl4 treatment, and bile acid homeostasis was disrupted. Liver injury was induced in both wild-type and FXR–/– mice by CCl4, but FXR–/– mice had more severe defects in liver repair than wild-type mice. FXR–/– livers had a decreased peak of regenerative DNA synthesis and reduced induction of genes involved in liver regeneration. Moreover, FXR–/– mice displayed increased mortality and enhanced hepatocyte deaths. During the early stages of liver repair after CCl4 treatment, we observed overproduction of TNF and a strong decrease of phosphorylation and DNA-binding activity of signal transducer and activator of transcription 3 in livers from FXR–/– mice. Exogenous expression of a constitutively active signal transducer and activator of transcription 3 protein in FXR–/– liver effectively reduced hepatocyte death and liver injury after CCl4 treatment. These results suggest that FXR is required to regulate normal liver repair by promoting regeneration and preventing cell death.

  V. P Francone , M. F Ifrim , C Rajagopal , C. J Leddy , Y Wang , J. H Carson , R. E Mains and B. A. Eipper
 

Neurons and endocrine cells package peptides in secretory granules (large dense-core vesicles) for storage and stimulated release. Studies of peptidylglycine -amidating monooxygenase (PAM), an essential secretory granule membrane enzyme, revealed a pathway that can relay information from secretory granules to the nucleus, resulting in alterations in gene expression. The cytosolic domain (CD) of PAM, a type 1 membrane enzyme essential for the production of amidated peptides, is basally phosphorylated by U2AF homology motif kinase 1 (Uhmk1) and other Ser/Thr kinases. Proopiomelanocortin processing in AtT-20 corticotrope tumor cells was increased when Uhmk1 expression was reduced. Uhmk1 was concentrated in the nucleus, but cycled rapidly between nucleus and cytosol. Endoproteolytic cleavage of PAM releases a soluble CD fragment that localizes to the nucleus. Localization of PAM-CD to the nucleus was decreased when PAM-CD with phosphomimetic mutations was examined and when active Uhmk1 was simultaneously overexpressed. Membrane-tethering Uhmk1 did not eliminate its ability to exclude PAM-CD from the nucleus, suggesting that cytosolic Uhmk1 could cause this response. Microarray analysis demonstrated the ability of PAM to increase expression of a small subset of genes, including aquaporin 1 (Aqp1) in AtT-20 cells. Aqp1 mRNA levels were higher in wild-type mice than in mice heterozygous for PAM, indicating that a similar relationship occurs in vivo. Expression of PAM-CD also increased Aqp1 levels whereas expression of Uhmk1 diminished Aqp1 expression. The outlines of a pathway that ties secretory granule metabolism to the transcriptome are thus apparent.

  Y Wang and W. H. Wu
 

Potassium (K+) is one of the essential macronutrients for plant growth and development. However, K+ content in soils is usually limited so that the crop yields are restricted. Plants may adapt to K+-deficient environment by adjusting their physiological and morphological status, indicating that plants may have evolved their sensing and signaling mechanisms in response to K+-deficiency. This short review particularly discusses some components as possible sensors or signal transducers involved in plant sensing and signaling in response to K+-deficiency, such as K+ channels and transporters, H+-ATPase, some cytoplasmic enzymes, etc. Possible involvement of Ca2+ and ROS signals in plant responses to K+-deficiency is also discussed.

  C Zhang , S Zheng , Y Wang , Y Zhao , J Zhu and L. Ge
 

Cleidocranial dysplasia (CCD) is a dominantly inherited skeletal dysplasia caused by mutations in the osteoblast-specific transcription factor-encoding gene, RUNX2. To correlate different RUNX2 mutations with CCD clinical spectrum, we studied six independent Chinese CCD patients. In five patients, mutations were detected in the coding region of the RUNX2 gene, including two frameshift mutations and three missense mutations. Of these mutations, four were novel and one had previously been reported. All the detected mutations were exclusively clustered within the Runt domain that affected conserved residues in the Runt domain. In vitro green fluorescent protein fusion studies showed that the three mutations—R225L, 214fs and 172fs—interfered with nuclear accumulation of RUNX2 protein, while T200I mutation had no effect on the subcellular distribution of RUNX2. There was no marked phenotypic difference between patients in craniofacial and clavicles features, while the expressivity of supernumerary teeth in our patient cohort had a striking variation, even among family members. The occurrence of intrafamilial clinical variability raises the view that hypomorphic effects and genetic modifiers may alter the clinical expressivity of these mutations. Our results provide new genetic evidence that mutations involved in RUNX2 contribute to CCD.

  M Bhaskaran , Y Wang , H Zhang , T Weng , P Baviskar , Y Guo , D Gou and L. Liu
 

MicroRNAs (miRNAs) are small endogenous RNAs and are widely regarded as one of the most important regulators of gene expression in both plants and animals. To define the roles of miRNAs in fetal lung development, we profiled the miRNA expression pattern during lung development with a miRNA microarray. We identified 21 miRNAs that showed significant changes in expression during lung development. These miRNAs were grouped into four distinct clusters based on their expression pattern. Cluster 1 contained miRNAs whose expression increased as development progressed, while clusters 2 and 3 showed the opposite trend of expression. miRNAs in cluster 4 including miRNA-127 (miR-127) had the highest expression at the late stage of fetal lung development. Quantitative real-time PCR validated the microarray results of six selected miRNAs. In situ hybridization demonstrated that miR-127 expression gradually shifted from mesenchymal cells to epithelial cells as development progressed. Overexpression of miR-127 in fetal lung organ culture significantly decreased the terminal bud count, increased terminal and internal bud sizes, and caused unevenness in bud sizes, indicating improper development. These findings suggest that miR-127 may have an important role in fetal lung development.

  Y Wang , B. R Weil , J. L Herrmann , A. M Abarbanell , J Tan , T. A Markel , M. L Kelly and D. R. Meldrum
 

Human bone marrow mesenchymal stem cells (MSCs) are a potent source of growth factors, which are partly responsible for their beneficial paracrine effects. We reported previously that transforming growth factor- (TGF-), a putative mediator of wound healing and the injury response, increases the release of vascular endothelial growth factor (VEGF), augments tumor necrosis factor- (TNF-)-stimulated VEGF production, and activates mitogen-activated protein kinases and phosphatidylinositol 3-kinase (PI-3K) pathway in human MSCs. The experiments described in this report indicate that TGF- increases MSC-derived hepatocyte growth factor (HGF) production. TGF--stimulated HGF production was abolished by inhibition of MEK, p38, PI-3K, or by small interfering RNA (siRNA) targeting TNF receptor 2 (TNFR2), but was not attenuated by siRNA targeting TNF receptor 1 (TNFR1). Ablation of TNFR1 significantly increased basal and stimulated HGF. A potent synergy between TGF- and TNF- was noted in MSC HGF production. This synergistic effect was abolished by MEK, P38, PI-3K inhibition, or by ablation of both TNF receptors using siRNA. We conclude that 1) novel cross talk occurs between tumor necrosis factor receptor and TGF-/epidermal growth factor receptor in stimulating MSC HGF production; 2) this cross talk is mediated, at least partially, via activation of MEK, p38, and PI-3K; 3) TGF- stimulates MSCs to produce HGF by MEK, p38, PI-3K, and TNFR2-dependent mechanisms; and 4) TNFR1 acts to decrease basal TGF- and TNF--stimulated HGF.

  J Feng , E Lucchinetti , G Enkavi , Y Wang , P Gehrig , B Roschitzki , M. C Schaub , E Tajkhorshid , K Zaugg and M. Zaugg
 

Phosphorylation of adenine nucleotide translocator 1 (ANT1) at residue Y194, which is part of the aromatic ladder located within the lumen of the carrier, critically regulates mitochondrial metabolism. Recent data support the concept that members of the Src family of nonreceptor tyrosine kinases are constitutively present in mitochondria and key to regulation of mitochondrial function. Herein, we demonstrate that site mutations of ANT1 (Y190->F190, Y194->F194) mimicking dephosphorylation of the aromatic ladder resulted in loss of oxidative growth and ADP/ATP exchange activity in respiration-incompetent yeast expressing mutant chimeric yN-hANT1. ANT1 is phosphorylated at Y194 by the Src family kinase members Src and Lck, and increased phosphorylation is tightly linked to reduced cell injury in preconditioned protected vs. unprotected cardiac mitochondria. Molecular dynamics simulations find the overall structure of the phosphorylated ANT1 stable, but with an increased steric flexibility in the region of the aromatic ladder, matrix loop m2, and four helix-linking regions. Combined with an analysis of the putative cytosolic salt bridge network, we reason that the effect of phosphorylation on transport is likely due to an accelerated transition between the main two conformational states (cm) of the carrier during the transport cycle. Since "aromatic signatures" are typical for other mitochondrial carrier proteins with important biological functions, our results may be more general and applicable to these carriers.

  Y Wang , D Liang , S Wang , Z Qiu , X Chu , S Chen , L Li , X Nie , R Zhang , Z Wang and D. Zhu
 

It has been previously reported by us that hypoxia activates lung 15-lipoxygenase (15-LO), which catalyzes arachidonic acid to 15-hydroxyeicosatetraenoic acid (15-HETE), leading to the constriction of pulmonary artery (PA). Rho-associated serine/threonine kinase (ROK), a downstream effector of small GTPase RhoA that may be modulated by G-protein and tyrosine kinase, plays an important role in smooth muscle contraction. However, whether the 15-HETE induced PA vasoconstriction involves the Rho/ROK pathway remains to be demonstrated. Therefore, we studied the contribution of ROK as well as G-protein and tyrosine kinase to the 15-HETE induced pulmonary vasoconstriction using PA ring technique, RNA interference technology, RP-HPLC, western blot and RT-PCR combined with the blockers. The hypoxia-induced expression of ROK is regulated by 15-HETE in rat PA smooth muscle cells (PASMCs), leading to vasoconstriction. The up-regulation of ROK expression caused by 15-HETE appears to be mediated by the G-protein and tyrosine kinase pathways. The translocation of ROK2 from the nucleus to the cytoplasm during hypoxia exposure relies on the mechanism for 15-HETE production. These results suggest that 15-HETE may mediate the up-regulation of ROK expression through G-protein and tyrosine kinase pathways under hypoxic condition, leading to PA vasoconstriction.

  Y Chen , C Qian , C Guo , F Ge , X Zhang , X Gao , S Shen , B Lian , K Kitazato , Y Wang and S. Xiong
 

Nucleoside diphosphate phosphate transferase A (NDPK-A) has been shown to play critical roles in the regulation of proliferation, differentiation, growth and apoptosis of cells. Our previous study suggested that the disulphide cross-linkage between cysteine 4 (C4) and cysteine 145 (C145) of NDPK-A might be a possible regulator of its activity. To confirm this hypothesis, the C145 residue of NDPK-A was mutated to serine, and the isomerization and biological activities of the mutant were investigated and compared with those of its wild-type counterpart. It was found the C145S mutation eliminated the intramolecular disulphide bond (DB) and prevented the formation of intermolecular DB, which was known to dissociate the hexameric NDPK-A into dimeric one. We also demonstrated that the C145S mutation didn’t affect the autologous hexamerization of this protein, and the mutant had increased bioactivities including phosphate transferase and DNase. These findings support the hypothesis that the formation of DBs in NDPK-A is involved in the regulation of the oligomerization and bioactivity of this multiple function protein, and that C145 is a key residue in the regulation of NDPK-A. In addition, the C145S mutant that we have constructed might be an attractive candidate for use in applications that require NDPK-A.

  T Wang , G Hou , Y Wang and L. Xue
 

Although interactions between the nuclear matrix and special regions of chromosomal DNA called matrix attachment regions (MARs) are implicated in various nuclear functions, the understanding of the regulatory mechanism of MARs is still poor. A few MAR-binding proteins (MARBP) have been isolated from some plants and animals, but not from the unicellular algae. Here, we identify a novel MAR-binding protein, namely DMBP-1, from the halotolerant alga Dunaliella salina. The cDNA of DMBP-1 is 2322-bp long and contains a 1626 bp of an open reading frame encoding a polypeptide of 542 amino acids (59 kDa). The DMBP-1 expressed in Escherichia coli specifically binds A/T-rich MAR DNA. The DMBP-1 fused to green fluorescent protein appears only inside the nuclei of Chinese hamster ovarian cells transfected with the pEGFP–MBP, indicating that the protein is located in the nuclei. The findings mentioned above may contribute to better understanding of the nuclear matrix–MAR interactions.

  M Jiang , X Xu , Y Wang , F Toyoda , X. S Liu , M Zhang , R. B Robinson and G. N. Tseng
 

Cardiac slow delayed rectifier (IKs) channel is composed of KCNQ1 (pore-forming) and KCNE1 (auxiliary) subunits. Although KCNE1 is an obligate IKs component that confers the uniquely slow gating kinetics, KCNE2 is also expressed in human heart. In vitro experiments suggest that KCNE2 can associate with the KCNQ1-KCNE1 complex to suppress the current amplitude without altering the slow gating kinetics. Our goal here is to test the role of KCNE2 in cardiac IKs channel function. Pulse-chase experiments in COS-7 cells show that there is a KCNE1 turnover in the KCNQ1-KCNE1 complex, supporting the possibility that KCNE1 in the IKs channel complex can be substituted by KCNE2 when the latter is available. Biotinylation experiments in COS-7 cells show that although KCNE1 relies on KCNQ1 coassembly for more efficient cell surface expression, KCNE2 can independently traffic to the cell surface, thus becoming available for substituting KCNE1 in the IKs channel complex. Injecting vesicles carrying KCNE1 or KCNE2 into KCNQ1-expressing oocytes leads to KCNQ1 modulation in the same manner as KCNQ1+KCNEx (where x = 1 or 2) cRNA coinjection. Thus, free KCNEx peptides delivered to the cell membrane can associate with existing KCNQ1 channels to modulate their function. Finally, adenovirus-mediated KCNE2 expression in adult guinea pig ventricular myocytes exhibited colocalization with native KCNQ1 protein and reduces the native IKs current density. We propose that in cardiac myocytes the IKs current amplitude is under dynamic control by the availability of KCNE2 subunits in the cell membrane.

  S Bunda , Y Wang , T. F Mitts , P Liu , S Arab , M Arabkhari and A. Hinek
 

We previously demonstrated that aldosterone, which stimulates collagen production through the mineralocorticoid receptor (MR)-dependent pathway, also induces elastogenesis via a parallel MR-independent mechanism involving insulin-like growth factor-I receptor (IGF-IR) signaling. The present study provides a more detailed explanation of this signaling pathway. Our data demonstrate that small interfering RNA-driven elimination of MR in cardiac fibroblasts does not inhibit aldosterone-induced IGF-IR phosphorylation and subsequent increase in elastin production. These results exclude the involvement of the MR in aldosterone-induced increases in elastin production. Results of further experiments aimed at identifying the upstream signaling component(s) that might be activated by aldosterone also eliminate the putative involvement of pertussis toxin-sensitive Gi proteins, which have previously been shown to be responsible for some MR-independent effects of aldosterone. Instead, we found that small interfering RNA-dependent elimination of another heterotrimeric G protein, G13, eliminates aldosterone-induced elastogenesis. We further demonstrate that aldosterone first engages G13 and then promotes its transient interaction with c-Src, which constitutes a prerequisite step for aldosterone-dependent activation of the IGF-IR and propagation of consecutive downstream elastogenic signaling involving phosphatidylinositol 3-kinase/Akt. In summary, the data we present reveal new details of an MR-independent cellular signaling pathway through which aldosterone stimulates elastogenesis in human cardiac fibroblasts.

  J. X Liu , B Hu , Y Wang , J. F Gui and W. Xiao
 

Studies have attributed several functions to the Eaf family, including tumor suppression and eye development. Given the potential association between cancer and development, we set forth to explore Eaf1 and Eaf2/U19 activity in vertebrate embryogenesis, using zebrafish. In situ hybridization revealed similar eaf1 and eaf2/u19 expression patterns. Morpholino-mediated knockdown of either eaf1 or eaf2/u19 expression produced similar morphological changes that could be reversed by ectopic expression of target or reciprocal-target mRNA. However, combination of Eaf1 and Eaf2/U19 (Eafs)-morpholinos increased the severity of defects, suggesting that Eaf1 and Eaf2/U19 only share some functional redundancy. The Eafs knockdown phenotype resembled that of embryos with defects in convergence and extension movements. Indeed, knockdown caused expression pattern changes for convergence and extension movement markers, whereas cell tracing experiments using kaeda mRNA showed a correlation between Eafs knockdown and cell migration defects. Cardiac and pancreatic differentiation markers revealed that Eafs knockdown also disrupted midline convergence of heart and pancreatic organ precursors. Noncanonical Wnt signaling plays a key role in both convergence and extension movements and midline convergence of organ precursors. We found that Eaf1 and Eaf2/U19 maintained expression levels of wnt11 and wnt5. Moreover, wnt11 or wnt5 mRNA partially rescued the convergence and extension movement defects occurring in eafs morphants. Wnt11 and Wnt5 converge on rhoA, so not surprisingly, rhoA mRNA more effectively rescued defects than either wnt11 or wnt5 mRNA alone. However, the ectopic expression of wnt11 and wnt5 did not affect eaf1 and eaf2/u19 expression. These data indicate that eaf1 and eaf2/u19 act upstream of noncanonical Wnt signaling to mediate convergence and extension movements.

  Y. C Han , C. Y Park , G Bhagat , J Zhang , Y Wang , J. B Fan , M Liu , Y Zou , I. L Weissman and H. Gu
 

The function of microRNAs (miRNAs) in hematopoietic stem cells (HSCs), committed progenitors, and leukemia stem cells (LSCs) is poorly understood. We show that miR-29a is highly expressed in HSC and down-regulated in hematopoietic progenitors. Ectopic expression of miR-29a in mouse HSC/progenitors results in acquisition of self-renewal capacity by myeloid progenitors, biased myeloid differentiation, and the development of a myeloproliferative disorder that progresses to acute myeloid leukemia (AML). miR-29a promotes progenitor proliferation by expediting G1 to S/G2 cell cycle transitions. miR-29a is overexpressed in human AML and, like human LSC, miR-29a-expressing myeloid progenitors serially transplant AML. Our data indicate that miR-29a regulates early hematopoiesis and suggest that miR-29a initiates AML by converting myeloid progenitors into self-renewing LSC.

  B Liu , J Yao , Y Wang , H Li and F. Qin
 

Protons, which are released during inflammation and injury, regulate many receptors and ion channels involved in pain transduction, including capsaicin channels (transient receptor potential vanilloid receptors 1). Whereas extracellular acidification both sensitizes and directly activates the channel, it also causes concomitant reduction of the unitary current amplitudes. Here, we investigate the mechanisms and molecular basis of this inhibitory effect of protons on channel conductance. Single-channel recordings showed that the unitary current amplitudes decreased with extracellular pH in a dose-dependent manner, consistent with a model in which protons bind to a site within the channel with an apparent pKa of ~6. The inhibition was voltage dependent, ~65% at –60 mV and 37% at +60 mV when pH was reduced from 7.4 to 5.5. The unitary current amplitudes reached saturation at [K+] ≥ 1 M, and notably the maximum amplitudes did not converge with different pHs, inconsistent with a blockade model based on surface charge screening or competitive inhibition of permeating ions. Mutagenesis experiments uncovered two acidic residues critical for proton inhibition, one located at the pore entrance and the other on the pore helix. Based on homology to the KcsA structure, the two acidic residues, along with another basic residue also on the pore helix, could form a triad interacting with each other through extensive hydrogen bonds and electrostatic contacts, suggesting that protons may mediate the interactions between the selectivity filter and pore helix, thereby altering the local structure in the filter region and consequently the conductance of the channel.

 
 
 
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