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Articles by B Chen
Total Records ( 10 ) for B Chen
  B Chen , Y Ma , R Meng , Z Xiong , C Zhang , G Chen , A Zhang and Y. Dong
 

Proteasome inhibitors are involved in cell cycle control, growth and inflammatory signaling, and transcriptional regulation of mitotic cells. A recent study has suggested that specific proteasome inhibitor MG132 may suppress cardiomyocyte hypertrophy in vitro. However, the underlying molecular mechanisms are not clear. In this study, we investigated the effects of long-term MG132 treatment on cardiac hypertrophy and the related molecular mechanisms in vivo. MG132 (0.1 mg/kg/day) was intraperitoneally injected to rats with abdominal aortic banding (AAB) for 8 weeks. Results showed that treatment with MG132 significantly attenuated left ventricular (LV) myocyte area, LV weight/body weight, and lung weight/body weight ratios, decreased LV diastolic diameter and wall thickness, and increased fractional shortening in AAB rats. AAB induced the phosphorylation of ERK1/2, JNK1, and p38 in cardiac myocytes. The elevated phosphorylation levels of ERK1/2 and JNK1 in AAB rats were significantly reversed by MG132 treatment. In conclusion, our results suggested that long-term treatment with MG132 attenuates pressure-overload-induced cardiac hypertrophy and improves cardiac function in AAB rats through regulation of ERK1/2 and JNK1 signaling pathways.

  H Cheng , N Sun , X Sun , B Chen , F Li , J Feng , L Cheng and Y. Cao
 

Platinum-based chemotherapeutics are the most common regimens for advanced non-small-cell lung cancer (NSCLC) patients. However, it is difficult to identify platinum resistance in clinical treatment. Genetic factors are thought to represent important determinants of drug efficacy. In this study, we investigated whether single-nucleotide polymorphisms (SNPs) in human mutS homolog 2 (hMSH2) and the human mutL homolog 1 (hMLH1) were associated with the tumor response in advanced NSCLC patients received platinum-based chemotherapy in Chinese population. Totally, 96 patients with advanced NSCLC were routinely treated with cisplatin- or carboplatin-based chemotherapy. The three-dimensional (3D), polyacrylamide gel-based DNA microarray method was used to evaluate the genotypes of hMSH2 gIVS12-6T/C and hMLH1-1151T/A with peripheral lymphocytes. We found that there was a significantly increased chance of treatment response to platinum-based chemotherapy with the hMSH2 gIVS12-6T/C polymorphism. The 3D polyacrylamide gel-based DNA microarray method is accurate, high-throughput, and inexpensive, especially suitable for a large scale of SNP genotyping in population.

  S Wei , A Guo , B Chen , W Kutschke , Y. P Xie , K Zimmerman , R. M Weiss , M. E Anderson , H Cheng and L. S. Song
  Rationale:

The transverse tubule (T-tubule) system is the ultrastructural substrate for excitation–contraction coupling in ventricular myocytes; T-tubule disorganization and loss are linked to decreased contractility in end stage heart failure (HF).

Objective:

We sought to examine (1) whether pathological T-tubule remodeling occurs early in compensated hypertrophy and, if so, how it evolves during the transition from hypertrophy to HF; and (2) the role of junctophilin-2 in T-tubule remodeling.

Methods and Results:

We investigated T-tubule remodeling in relation to ventricular function during HF progression using state-of-the-art confocal imaging of T-tubules in intact hearts, using a thoracic aortic banding rat HF model. We developed a quantitative T-tubule power (TTpower) index to represent the integrity of T-tubule structure. We found that discrete local loss and global reorganization of the T-tubule system (leftward shift of TTpower histogram) started early in compensated hypertrophy in left ventricular (LV) myocytes, before LV dysfunction, as detected by echocardiography. With progression from compensated hypertrophy to early and late HF, T-tubule remodeling spread from the LV to the right ventricle, and TTpower histograms of both ventricles gradually shifted leftward. The mean LV TTpower showed a strong correlation with ejection fraction and heart weight to body weight ratio. Over the progression to HF, we observed a gradual reduction in the expression of a junctophilin protein (JP-2) implicated in the formation of T-tubule/sarcoplasmic reticulum junctions. Furthermore, we found that JP-2 knockdown by gene silencing reduced T-tubule structure integrity in cultured adult ventricular myocytes.

Conclusions:

T-tubule remodeling in response to thoracic aortic banding stress begins before echocardiographically detectable LV dysfunction and progresses over the development of overt structural heart disease. LV T-tubule remodeling is closely associated with the severity of cardiac hypertrophy and predicts LV function. Thus, T-tubule remodeling may constitute a key mechanism underlying the transition from compensated hypertrophy to HF.

  G. S Song , H. L Zhai , Y. G Peng , L Zhang , G Wei , X. Y Chen , Y. G Xiao , L Wang , Y. J Chen , B Wu , B Chen , Y Zhang , H Chen , X. J Feng , W. K Gong , Y Liu , Z. J Yin , F Wang , G. Z Liu , H. L Xu , X. L Wei , X. L Zhao , P. B. F Ouwerkerk , T Hankemeier , T Reijmers , R. v. d Heijden , C. M Lu , M Wang , J. v. d Greef and Z. Zhu
 

Heterosis is a biological phenomenon whereby the offspring from two parents show improved and superior performance than either inbred parental lines. Hybrid rice is one of the most successful apotheoses in crops utilizing heterosis. Transcriptional profiling of F1 super-hybrid rice Liangyou-2186 and its parents by serial analysis of gene expression (SAGE) revealed 1183 differentially expressed genes (DGs), among which DGs were found significantly enriched in pathways such as photosynthesis and carbon-fixation, and most of the key genes involved in the carbon-fixation pathway exhibited up-regulated expression in F1 hybrid rice. Moreover, increased catabolic activity of corresponding enzymes and photosynthetic efficiency were also detected, which combined to indicate that carbon fixation is enhanced in F1 hybrid, and might probably be associated with the yield vigor and heterosis in super-hybrid rice. By correlating DGs with yield-related quantitative trait loci (QTL), a potential relationship between differential gene expression and phenotypic changes was also found. In addition, a regulatory network involving circadian-rhythms and light signaling pathways was also found, as previously reported in Arabidopsis, which suggest that such a network might also be related with heterosis in hybrid rice. Altogether, the present study provides another view for understanding the molecular mechanism underlying heterosis in rice.

  E Neven , G Dams , A Postnov , B Chen , N De Clerck , M. E De Broe , P. C D`Haese and V. Persy
 

Background. Hyperphosphataemia is a risk factor for arterial calcification contributing to the high cardiovascular mortality in patients with chronic kidney disease. Calcium-based phosphate binders can induce hypercalcaemia and are associated with progression of vascular calcification. Therefore, the effect of lanthanum carbonate, a non-calcium phosphate binder, on the development of vascular calcification was investigated in uraemic rats.

Methods. Chronic renal failure (CRF) was induced by feeding rats an adenine-enriched diet for 4 weeks. After 2 weeks, 1% or 2% lanthanum carbonate was added to the diet for 6 weeks. Calcification in the aorta, carotid and femoral arteries was evaluated histomorphometrically, biochemically and by ex vivo micro-CT. Chondro-/osteogenic conversion of vascular smooth muscle cells was also analysed in the rat aorta.

Results. Treatment with 1% lanthanum carbonate (1% La) did not reduce vascular calcification, but in the 2% lanthanum carbonate (2% La) group vascular calcium content and area% Von Kossa positivity were decreased compared with control CRF rats. The aortic calcified volume measured with ex vivo micro-CT was significantly reduced in rats treated with 2% La. Although calcification was inhibited by treatment with 2% La, the chondrocyte transcription factor sox-9 was abundantly expressed in the aorta.

Conclusion. Treatment of CRF rats with 2% La reduces the development of vascular calcification by adequate phosphate binding resulting in a decreased supply of phosphate as a substrate for vascular calcification.

  W Zhuo , B Chen and M. Wei
 

For estimating indoor thoron (220Rn) progeny concentrations with 220Rn measurements, both theoretical studies and field measurements were carried out in this work. Based on the theoretical study, it was found that the exhalation rate of 220Rn (ETn) could be optimally assessed with the 220Rn concentration measured at a point of 50 cm far from the source wall, and the equilibrium equivalent thoron concentration (EETC) could be further estimated with the ETn and the area of wall surface as well as the room volume. Field measurements testified that the estimated EETCs were in general agreement with the directly measured results with an average ratio of 0.87 ± 0.12. The new method developed in this study is thought to be preferable for long-term and large-scale surveys of indoor EETC.

  C Zhao , W Zhuo , B Chen and H. Zhang
 

For calibration and intercomparison experiments, a thoron chamber with an inner volume of 300 l was designed based on a programmable constant temperature and humidity testing device in this work. The commercial lantern mantles enriched with 232Th were used as the 220Rn source and the mantles were set in 3x3x3 points of lattice style inside the chamber. Experimental studies showed that 220Rn concentrations in the chamber could be easily controlled and adjusted from about 0.5 to 80 kBq m–3 through manual settings of the relative humidity and temperature, and the spatial distribution of 220Rn in the chamber was fairly homogeneous.

  F Tang , W Zhuo , C Zhao , B Chen , Y Xu and L. He
 

For accurate measurements of 220Rn concentration with airflow-through scintillation cell method, a theoretical study was performed for discussing the influences of sampling flow rate, volumes of sampling tube and scintillation cell on the measurements. It is found that a high flow rate and a large inner volume of scintillation cell as well as a small inner volume of sampling tube are not only preferable for measuring low levels of 220Rn, but also helpful for enhancing the measurement accuracy. In calibration experiments, both the sampling flow rate and the sampling tube volume should be noted. The variations of the flow rate and tube volume should be considered for accurate measurements in the fields.

  B Chen , D Guan , Z. J Cui , X Wang and X. Shen
 

To know whether thioredoxin 1 (Trx1) works for an antioxidant defense mechanism in atherosclerosis, the effect of Trx1 on the release of monocyte chemoattractant protein-1 (MCP-1), a potent chemoattractant for recruitment and accumulation of monocytes/macrophages in the intima of artery vessel, was investigated in human endothelial-like EA.hy 926 cells. It was found that overexpression of Trx1 suppressed, whereas knockdown of endogenous Trx1 enhanced, oxidized low-density lipoprotein (oxLDL)-stimulated MCP-1 release and expression in the cells. It was also observed that overexpression of Trx1 suppressed, whereas depletion of endogenous Trx1 greatly promoted, nuclear translocation of c-Jun and the redox factor-1 (Ref-1). Electrophoretic mobility shift assay showed significantly reduced DNA-binding activity of activator protein-1 (AP-1) in Trx1-overexpressing cells but apparently enhanced DNA binding activity of AP-1 in Trx1-knockdown cells, indicating that nuclear Ref-1 rather than Trx1 itself finally dominates the regulation of AP-1 activity, although Trx1 is considered to upregulate AP-1 activity. It was also observed that Trx1 depressed intracellular generation of reactive oxygen species (ROS). Diphenyleneiodonium (DPI), the inhibitor of NADPH oxidase, suppressed MCP-1 secretion, whereas transient expression of Nox1 enhanced transcription of MCP-1 in endothelial cells. Assays with AP-1 and MCP-1 luciferase reporters further demonstrated that transient expression of Trx1 significantly depressed the transcriptional activity of c-Jun/c-Fos and consequent MCP-1 transcription. This study suggests that Trx1 inherently suppresses MCP-1 expression in vascular endothelium and may prevent atherosclerosis by depressing MCP-1 release. Besides the suppression of intracellular ROS generation, the inhibition of nuclear translocation of AP-1 and Ref-1 are mainly responsible for the downregulation of MCP-1 by Trx1.

  B Chen , M. S Longtine , Y Sadovsky and D. M. Nelson
 

Hypoxia is commonly assigned a role in the placental dysfunction characteristic of preeclampsia and intrauterine growth restriction. We previously showed that hypoxia upregulates p53 and enhances apoptosis in primary cultures of human cytotrophoblasts. Here we tested the hypothesis that hypoxia also induces apoptosis in syncytiotrophoblasts by upregulation of p53. Primary cultures of human cytotrophoblasts that had differentiated into syncytiotrophoblasts by 52 h were exposed for ≤24 h to 20% or <1% oxygen in the presence or absence of staurosporine or the p53 modulators nutlin-3, pifithrin-, and pifithrin-µ. Proteins were detected by Western blot analysis or immunofluorescence. Compared with 20% oxygen, exposure of syncytiotrophoblasts to <1% oxygen upregulated hypoxia-inducible factor (HIF)-1 and rapidly downregulated p53. Activity of p53 in hypoxic syncytiotrophoblasts was reduced by the higher expression of the negative p53 regulator MDMX and by the reduction of phosphorylation of p53 at Ser392, which reduces p53 activity. Conversely, staurosporine, a kinase inhibitor, and nutlin-3, a drug that enhances p53 expression, both raised p53 levels and increased the rate of apoptosis in syncytiotrophoblasts compared with vehicle controls. Immunofluorescence staining showed p53 immunolocalized to both cytoplasm and nuclei of nutlin-3-exposed syncytiotrophoblasts. The hypoxia-induced apoptosis in syncytiotrophoblasts correlated with enhanced expression of the proapoptotic BAD and a reduced level of antiapoptotic BAD phosphorylated on Ser112. We surmise that cell death induced by extreme hypoxia in syncytiotrophoblasts follows a non-p53-dependent pathway, unlike that of a nonhypoxic stimulus and unlike hypoxic cytotrophoblasts. We speculate that downregulation of p53 activity in response to hypoxia reduces or eliminates the apoptosis transduced by the p53 pathway in syncytiotrophoblasts, thereby limiting cell death and maintaining the integrity of this critical villous component.

 
 
 
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