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Articles by J Jiang
Total Records ( 8 ) for J Jiang
  J Gu , D Sun , Q Zheng , X Wang , H Yang , J Miao , J Jiang and W. Wei
 

Elongator complex has been associated with hyperphosphorylated RNA polymerase II and is known to play critical roles in transcriptional elongation, as well as in tRNA modification and exocytosis. However, the specific mechanism of how human Elongator complex regulates cell growth and cell cycle remains unclear. To investigate the composition of human Elongator complex and its effects on cell growth, 293T cells were established that stably overexpressed Flag-Elp3 and Flag-Elp4. By using anti-Flag M2 antibody-bound resin, a core Elongator complex was purified from cells that stably overexpressed Flag-Elp3. No Elongator complex was purified from cells stably transfected with pFlagCMV4-Elp4. Interestingly, the cell growth was inhibited in 293T cells transfected with pFlagCMV4-Elp3. Flow cytometry analysis showed that most of the cells stably overexpressing Flag-Elp3 were found in G1 stage, indicating a role of the core Elongator in the G1 checkpoint for the regulation of cell cycle. We observed increased basal transcription and remarkably enhanced transcription stimulated by VP16 in 293T cells overexpressing Flag-Elp3. The transcription could also be synergistically activated by overexpressing both Elp3 and Elp4. Taken together, our results suggested that the core Elongator complex formed by Elp1, Elp2, and Elp3 was rather stable, whereas Elp4, Elp5, and Elp6 might loosely contact and work together with the core Elongator to regulate cell functions.

  X Fan , Y Liu , J Jiang , Z Ma , H Wu , T Liu , M Liu , X Li and H. Tang
 

MicroRNAs (miRNAs) are emerging as a class of small regulated RNAs, and the alterations of miRNAs are implicated in the initiation and progression of human cancers. Our study shows that inhibition of miR-20a in OVCAR3 ovarian cancer cell line could suppress, whereas overexpression of miR-20a could enhance cell long-term proliferation and invasion. We also confirmed amyloid precursor protein (APP) as a direct target gene of miR-20a. Furthermore, suppression of APP expression could also promote ovarian cancer cell proliferation and invasion, which is consistent with the results of miR-20a overexpression. Therefore, we concluded that the regulation of APP is an important mechanism for miR-20a to promote proliferation and invasion in ovarian cancer cells.

  D. R Potter , J Jiang and E. R. Damiano
 

Compelling evidence continues to emerge suggesting that the glycocalyx surface layer on vascular endothelial cells plays a determining role in numerous physiological processes including inflammation, microvascular permeability, and endothelial mechanotransduction. Previous research has shown that enzymes degrade the glycocalyx, whereas inflammation causes shedding of the layer. To track the endogenous recovery of the glycocalyx in vivo, we used fluorescent microparticle image velocimetry (µ-PIV) in mouse cremaster muscle venules to estimate the hydrodynamically relevant glycocalyx thickness 1, 3, 5, and 7 days after enzymatic or cytokine-mediated degradation of the layer. Results indicate that after acute degradation of the glycocalyx, 5 to 7 days are required for the layer to endogenously restore itself to its native hydrodynamically relevant thickness in vivo. In light of these findings, and because demonstrable evidence has emerged that standard cell culture conditions are not conducive to providing the environment and/or cellular conditions necessary to produce and maintain a physiologically relevant cell surface glycocalyx in vitro, we sought to determine whether merely the passage of time would be sufficient to promote the production of a hydrodynamically relevant glycocalyx on a confluent monolayer of human umbilical vein endothelial cells (HUVECs). Using µ-PIV, we found that the hydrodynamically relevant glycocalyx was substantially absent 7 days postconfluence on HUVEC-lined cylindrical collagen microchannels maintained under standard culture conditions. Thus, it remains to be determined how a hydrodynamically relevant glycocalyx surface layer can be synthesized and maintained in culture before the endothelial cell culture model can be used to elucidate glycocalyx-mediated mechanisms of endothelial cell function.

  J Jiang , N. L. S Tang , C Ohlsson , A. L Eriksson , L Vandenput , C Liao , X Wang , F. W. K Chan , A Kwok , E Orwoll , T. C. Y Kwok , J Woo and P. C. Leung
  BACKGROUND:

Results of recent studies have demonstrated that genetic variants of the enzyme steroid 5 reductase type II (SRD5A2) are associated with serum concentrations of major androgen metabolites such as conjugates of androstane-3,17β-diol-glucuronide (3-diol-G). However, this association was not consistently found among different ethnic groups. Thus, we aimed to determine whether the association with SRD5A2 genetic variations exists in a cohort of healthy Chinese elderly men, by examining 2 metabolite conjugates: androstane-3,l7β-diol-3-glucuronide (3-diol-3G) and androstane-3,17β-diol-17-glucuronide (3-diol-17G).

METHODS:

We used GC-MS and LC-MS to measure serum sex steroid concentrations, including testosterone and dihydrotestosterone, and 3-diol-3G and 3-diol-17G in 1182 Chinese elderly men age 65 and older. Genotyping of the 3 SRD5A2 tagSNPs [rs3731586, rs12470143, and rs523349 (V89L)] was performed by using melting-temperature–shift allele-specific PCR.

RESULTS:

The well-described SRD5A2 missense variant rs523349 (V89L) was modestly associated with the 3-diol-17G concentration (P = 0.040). On the other hand, SNP rs12470143 was found to be significantly correlated with 3-diol-3G concentration (P = 0.021). Results of haplotype analysis suggested that the presence of an A-C-G haplotype leads to an increased 3-diol-3G concentration, a finding consistent with results of single SNP analysis.

CONCLUSIONS:

The genetic variation of SRD5A2 is associated with circulating 3-diol-3G and 3-diol-17G concentrations in Chinese elderly men. In addition, we showed that SRD5A2 haplotypic association, rather than a single SNP alone, might be a better predictor of the 3-diol-G concentration. Thus, the effect of either the haplotype itself or of other ungenotyped SNPs in linkage disequilibrium with the haplotype is responsible for the interindividual variation of 3-diol-G.

  W Cao , C Xu , G Lou , J Jiang , S Zhao , M Geng , W Xi , H Li and Y. Jin
  Objective

The aim of this study was to assess the efficacy and toxicity of the combination of paclitaxel and nedaplatin as a first-line chemotherapy for patients with advanced esophageal cancer.

Methods

Patients with advanced esophageal cancer received 175 mg/m2 of paclitaxel over a 3 h infusion, followed by nedaplatin 80 mg/m2 in a 1 h infusion on day 1 every 3 weeks until the documented disease progression, unacceptable toxicity or patient's refusal.

Results

Between March 2005 and December 2007, 48 patients entered in the study. Forty-six (95.8%) of the 48 patients were assessable for response. The overall response rate was 41.7% (95% CI, 27.8–55.7%) with 2 complete responses and 18 partial responses. The median follow-up period was 20.5 months (range, 12.5–27.2 months). The median overall time to progression and overall survival (OS) were 6.1 months (95% CI, 4.8–7.4 months) and 11.5 months (95% CI, 9.1–13.9 months), respectively. The estimate of OS at 12 and 24 months was 43.8% (95% CI, 29.7–77.8%) and 10.4% (95% CI, 1.8–19.1%), respectively. Most patients experienced anemia, during their course of therapy with 6 (13.0%) patients for grade 3/4 anemia, and grade 1 or 2 anemia was detected in 23 (50%) patients. Grade 3 leucopenia, neutropenia and thrombocytopenia were documented in 8 (17.4%), 9 (17.4%) and 2 (4.3%) patients, respectively. Grade 3 nausea and vomiting were detected in 3 (6.5%) and 2 (4.3%) patients, respectively. Two patients (4.3%) were hospitalized because of treatment-related complications. The treatment was well tolerated and no toxic death occurred.

Conclusions

Combination of paclitaxel and nedaplatin is a tolerated treatment modality with promising activity in previously untreated advanced esophageal cancer.

  Y Gan , Y Zhang , D. J DiGirolamo , J Jiang , X Wang , X Cao , K. R Zinn , D. P Carbone , T. L Clemens and S. J. Frank
 

GH promotes longitudinal growth and regulates multiple cellular functions in humans and animals. GH signals by binding to GH receptor (GHR) to activate the tyrosine kinase, Janus kinase 2 (JAK2), and downstream pathways including signal transducer and activator of transcription 5 (STAT5), thereby regulating expression of genes including IGF-I. GH exerts effects both directly and via IGF-I, which signals by activating the IGF-I receptor (IGF-IR). IGF-IR is a cell surface receptor that contains intrinsic tyrosine kinase activity within its intracellular domain. In this study, we examined the potential role of IGF-IR in facilitating GH-induced signal transduction, using mouse primary calvarial osteoblasts with Lox-P sites flanking both IGF-IR alleles. These cells respond to both GH and IGF-I and in vitro infection with an adenovirus that drives expression of Cre recombinase (Ad-Cre) dramatically reduces IGF-IR abundance without affecting the abundance of GHR, JAK2, STAT5, or ERK. Notably, infection with Ad-Cre, but not a control adenovirus, markedly inhibited acute GH-induced STAT5 activity (more than doubling the ED50 and reducing the maximum activity by nearly 50%), while sparing GH-induced ERK activity, and markedly inhibited GH-induced transactivation of a STAT5-dependent luciferase reporter. The effect of Ad-Cre on GH signaling was specific, as platelet-derived growth factor-induced signaling was unaffected by Ad-Cre-mediated reduction of IGF-IR. Ad-Cre-mediated inhibition of GH signaling was reversed by adenoviral reexpression of IGF-IR, but not by infection with an adenovirus that drives expression of a hemagglutination-tagged somatostatin receptor, which drives expression of the unrelated somatostatin receptor, and Ad-Cre infection of nonfloxed osteoblasts did not affect GH signaling. Notably, infection with an adenovirus encoding a C-terminally truncated IGF-IR that lacks the tyrosine kinase domain partially rescued both acute GH-induced STAT5 activity and GH-induced IGF-I gene expression in cells in which endogenous IGF-IR was reduced. These data, in concert with our earlier findings that GH induces a GHR-JAK2-IGF-IR complex, suggest a novel function for IGF-IR. In addition to its role as a key IGF-I signal transducer, this receptor may directly facilitate acute GH signaling. The implications of these findings are discussed.

  X Kong , H Gan , Y Hao , C Cheng , J Jiang , Y Hong , J Yang , H Zhu , Y Chi , X Yun and J. Gu
 

CDK11p58, a CDK11 family Ser/Thr kinase, is a G2/M specific protein and contributed to regulation of cell cycle, transcription and apoptotic signal transduction. Recently, CDK11p58 has been reported to exert important functions in mitotic process, such as the regulation of bipolar spindle formation and sister chromatid cohesion. Here, we identified p21 activated kinase 1 (PAK1) as a new CDK11p58 substrate and we mapped a new phosphorylation site of Ser174 on PAK1. By mutagenesis, we created PAK1174A and PAK1174E, which mimic the dephosphorylated and phosphorylated form of PAK1; further analysis showed PAK1174E could be recruited to myosin V motor complex through binding to dynein light chain 2 (DLC2). PAK1174E could accelerate the mitosis progression in a nocodazole blocked cell model, while PAK1174A exhibited an opposite role. Our results indicated PAK1 may serve as a downstream effector of CDK11p58 during mitosis progression.

  H Bayir , A. A Kapralov , J Jiang , Z Huang , Y. Y Tyurina , V. A Tyurin , Q Zhao , N. A Belikova , I. I Vlasova , A Maeda , J Zhu , H. M Na , P. G Mastroberardino , L. J Sparvero , A. A Amoscato , C. T Chu , J. T Greenamyre and V. E. Kagan
 

Damage of presynaptic mitochondria could result in release of proapoptotic factors that threaten the integrity of the entire neuron. We discovered that -synuclein (Syn) forms a triple complex with anionic lipids (such as cardiolipin) and cytochrome c, which exerts a peroxidase activity. The latter catalyzes covalent hetero-oligomerization of Syn with cytochrome c into high molecular weight aggregates. Syn is a preferred substrate of this reaction and is oxidized more readily than cardiolipin, dopamine, and other phenolic substrates. Co-localization of Syn with cytochrome c was detected in aggregates formed upon proapoptotic stimulation of SH-SY5Y and HeLa cells and in dopaminergic substantia nigra neurons of rotenone-treated rats. Syn-cardiolipin exerted protection against cytochrome c-induced caspase-3 activation in a cell-free system, particularly in the presence of H2O2. Direct delivery of Syn into mouse embryonic cells conferred resistance to proapoptotic caspase-3 activation. Conversely, small interfering RNA depletion of Syn in HeLa cells made them more sensitive to dopamine-induced apoptosis. In human Parkinson disease substantia nigra neurons, two-thirds of co-localized Syn-cytochrome c complexes occurred in Lewy neurites. Taken together, these results indicate that Syn may prevent execution of apoptosis in neurons through covalent hetero-oligomerization of cytochrome c. This immediate protective function of Syn is associated with the formation of the peroxidase complex representing a source of oxidative stress and postponed damage.

 
 
 
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