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Articles by Y Wei
Total Records ( 6 ) for Y Wei
  D Sun , S Zhang , Y Wei and L. Yin

Mangostin (MAG), a kind of xanthone widely used in diet and medicine, has antioxidant, anti-inflammatory, antimicrobial, and anticancer activities. On account of its antioxidant activity, MAG might protect cancer cells from free radical damage in photodynamic therapy (PDT) during which reactive oxygen species production was stimulated leading to irreversible tumor cell injury. In this study, the antioxidant activity of MAG was investigated and the influence of MAG on K562 cells in 5-aminolevulinic acid (ALA)-based PDT is demonstrated. The results showed that MAG could scavenge hydroxyl radical, superoxide anion, and hydrogen peroxide and inhibit the formation of malondialdehyde (MDA), but increase the amounts of singlet oxygen in cell-free systems. MAG inhibits cell proliferation and enhances cell apoptosis, lipid peroxidation, and DNA damage in ALA-PDT on K562 cells. NaN3, a singlet oxygen quencher, suppresses the MAG-induced cell apoptosis, lipid peroxidation, and DNA damage. In conclusion, MAG enhances the PDT-induced cytotoxicity in K562 cells and singlet oxygen was involved in this process. These results implied that the effect of antioxidants on PDT might be determined by its sensitization ability to singlet oxygen.

  Y Zhou , P Lin , Q Li , L Han , H Zheng , Y Wei , Z Cui , Y Ni and X. Guo

Sputum is the most common sample collected from patients suffering from lower respiratory tract infections and it is crucial for the bacterial identification of these infections. In this study, we enrolled 101 sputum samples from 101 patients with lower respiratory tract infections. Initially, pyrosequencing of the 16S rDNA V3 hypervariable regions of the bacteria contained in the sputum was utilized as a culture-independent approach for microbiota analysis. For comparison, clinical laboratory tests using a culture-dependent automated bacterial identification system for the same cohort of sputum samples were also done. By pyrosequencing, >70,000 DNA fragments were found and classified into 129 bacterial genera after being analyzed by the Ribosomal Database Project (RDP) process. Most sequences belonged to several predominant genera, such as Streptococcus and Staphylococcus, indicating that these genera play an important role in lower respiratory tract infections. In addition, some sequences belonging to potential causative agents, such as Mycoplasma, Haemophilus, and Moraxella, were also found, but these sequences were not found by clinical laboratory tests. For the nine genera detected by both methods, the methods' sensitivities were compared and the results showed that pyrosequencing was more sensitive, except for Klebsiella and Mycobacterium. Significantly, this method revealed much more complicated bacterial communities and it showed a promising ability for the detection of bacteria.

  K. T Pfaffenbach , C. L Gentile , A. M Nivala , D Wang , Y Wei and M. J. Pagliassotti

Prolonged endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) have been linked to apoptosis via several mechanisms, including increased expression of C/EBP homologous protein (Chop). Increased long-chain fatty acids, in particular saturated fatty acids, induce ER stress, Chop expression, and apoptosis in liver cells. The first aim of the present study was to determine the role of Chop in lipid-induced hepatocyte cell death and liver injury induced by a methionine-choline-deficient diet. Albumin-bound palmitate increased Chop gene and protein expression in a dose-dependent fashion in H4IIE liver cells. siRNA-mediated silencing of Chop in H4IIE liver cells reduced thapsigargin-mediated cell death by ~40% and delayed palmitate-mediated cell death, but only at high concentrations of palmitate (400–500 µM). Similar results were observed in primary hepatocytes isolated from Chop-knockout mice. Indices of liver injury were also not reduced in Chop-knockout mice provided a methionine-choline-deficient diet. To ascertain whether ER stress was linked to palmitate-induced cell death, primary hepatocytes were incubated in the absence or presence of the chemical chaperones taurine-conjugated ursodeoxycholic acid or 4-phenylbutyric acid. The presence of either of these chemical chaperones protected liver cells from palmitate-mediated ER stress and cell death, in part, via inhibition of JNK activation. These data suggest that ER stress is linked to palmitate-mediated cell death via mechanisms that include JNK activation.

  B Liu , D Chen , L Yang , Y Li , X Ling , L Liu , W Ji , Y Wei , J Wang , Q Wei , L Wang and J. Lu

Mitogen-activated protein kinase kinase 4 (MKK4) is a critical mediator of stress-activated protein kinase signals that regulate apoptosis, inflammations and tumorigenesis. Several polymorphisms have been identified in the MKK4 gene. We hypothesized that genetic variants in the MKK4 promoter may alter its expression and thus cancer risk. In a case–control study of 1056 lung cancer cases and 1056 sex and age frequency-matched cancer-free controls, we genotyped two common polymorphisms in the MKK4 promoter region (–1304T>G and –1044A>T) with the Taqman assay, and we found that compared with the most common –1304TT genotype, carriers of –1304G variant genotypes had a decreased risk of lung cancer [odds ratio (OR) = 0.74; 95% confidence interval (CI) = 0.61–0.90 for TG, and OR = 0.62; 95% CI = 0.41–0.94 for GG] in an allele dose–response manner (adjusted Ptrend = 0.0005). Further stratification analysis showed that the protective role of the –1304G variant allele was more evident in low or normal body mass index (BMI) but restrained in the overweighters and that the –1304G variant genotypes interacted with BMI in reducing cancer risk (adjusted Pinteraction = 0.003). Moreover, the luciferase assay showed that the G allele in the promoter significantly increased the transcription activity of the MKK4 gene in vitro and that the MKK4 protein expression levels of the G variant carriers was significantly higher in tumor tissues than those of the –1304TT genotype. However, no significant association was observed between the –1044A>T polymorphism and risk of lung cancer. Our data suggest that the functional –1304G variant in the MKK4 promoter contributes to a decreased risk of lung cancer by increasing the promoter activity and that the G variant may be a marker for susceptibility to lung cancer.

  Y Wei , X. m Liu , K. J Peyton , H Wang , F. K Johnson , R. A Johnson and W. Durante

Hypochlorous acid (HOCl) is a unique oxidant generated by the enzyme myeloperoxidase that contributes to endothelial cell dysfunction and death in atherosclerosis. Since myeloperoxidase localizes with heme oxygenase-1 (HO-1) in and around endothelial cells of atherosclerotic lesions, the present study investigated whether there was an interaction between these two enzymes in vascular endothelium. Treatment of human endothelial cells with the myeloperoxidase product HOCl stimulated a concentration- and time-dependent increase in HO-1 protein that resulted in a significant rise in carbon monoxide (CO) production. The induction of HO-1 protein was preceded by a prominent increase in HO-1 mRNA and total and nuclear factor-erythroid 2-related factor 2 (Nrf2). In addition, HOCl induced a significant rise in HO-1 promoter activity that was blocked by mutating the antioxidant response element (ARE) in the promoter or by overexpressing a dominant-negative mutant of Nrf2. The HOCl-mediated induction of Nrf2 or HO-1 was blocked by the glutathione donor N-acetyl-l-cysteine but was unaffected by ascorbic or uric acid. Finally, treatment of endothelial cells with HOCl stimulated mitochondrial dysfunction, caspase-3 activation, and cell death that was potentiated by the HO inhibitor, tin protoporphyrin-IX, or by the knockdown of HO-1, and reversed by the exogenous administration of biliverdin, bilirubin, or CO. These results demonstrate that HOCl induces HO-1 gene transcription via the activation of the Nrf2/ARE pathway to counteract HOCl-mediated mitochondrial dysfunction and cell death. The ability of HOCl to activate HO-1 gene expression may represent a critical adaptive response to maintain endothelial cell viability at sites of vascular inflammation and atherosclerosis.

  Y Wei , Y Ge , F Zhou , H Chen , C Cui , D Liu , Z Yang , G Wu , J Gu and J. Jiang

ATF5, a member of ATF/CREB family of b-ZIP transcription factors, is highly expressed in a wide variety of neoplasms and regulates cell differentiation, cell survival and apoptosis. However, the mechanism of human ATF5 transcriptional regulation has not been clarified. Here, we identified the transcription start site of the ATF5 gene, cloned its 5'-flanking region and identified the region –105 to +3 relative to the transcription start site as that having promoter activity. This region contained potential binding sites for several transcription factors, including EBF1, Sp1 and E2F1. EBF1 transcription factor binds to the ATF5 promoter and regulates the ATF5 transcription in an EBF-binding site independent manner. Thus, our studies not only provided molecular basis of ATF5 transcriptional regulation, but also identified ATF5 as a target gene of EBF1 transcription factor.

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