I. The Study of Cellular MicroRNA Expression Regulated by Hepatitis C Virus Core Protein in Human Hepatoma Cell LinesII.The Investigation of the Effect of Inflammation on the Expression of Human UDP-Glucuronosyltransferase 1A1 Gene
| Autor: | Tzu-Yue Shiu, 徐祖岳 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 Chapter I. The Study of Cellular MicroRNA Expression Regulated by Hepatitis C Virus Core Protein in Human Hepatoma Cell Lines Chronic hepatitis C virus (HCV) infection contributes to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma, but the molecular pathogenesis is still unclear. HCV infection has been reported to modulate cellular microRNA (miRNA) expression. HCV core protein is believed to be involved in hepatocarcinogenesis by directly and indirectly regulating gene transcription, interfering with cellular signaling pathways, and affecting cell cycle and apoptosis. The full-length core protein is mainly found within the membranes of cytoplasmic organelles, whereas the mature form is trafficked to the nucleus. In this study, we examined miRNA expression profile in Huh7 cells transiently expressing full-length and mature HCV core protein using TaqMan low density array. Array data were further determined in Huh7 and HepG2 cells overexpressing full-length and mature core protein and in Huh7 cells expressing full-length HCV replicon. We demonstrate that the mature core protein modulates miR-345，miR-93，miR-138及miR-192 expression, and the full-length core protein modulates miR-192 expression. MiR-345 down-regulates p21Waf1/Cip1 gene expression by directly targeting its 3’ untranslated region (3’UTR). MiR-138 and miR-192 down-regulate telomerase reverse transcriptase (hTERT) and SIP1 gene expressions through directly targeting on their 3’ untranslated regions respectively. HCV core-induced miR-345 inhibits apoptosis through down-regulation of p21Waf1/Cip1 gene expression. Furthermore, the core protein regulates miR-138 and miR-192 expression to suppress cell proliferation by directly and indirectly inhibiting hTERT gene expression. This study may explain, in part, the molecular pathogenesis of multistep hepatocarcinogenesis during chronic HCV infection. Chapter II. The Investigation of the Effect of Inflammation on the Expression of Human UDP-Glucuronosyltransferase 1A1 Gene Jaundice or hyperbilirubinemia is a common complication of sepsis. However, the molecular pathogenesis of hyperbilirubinemia during inflammation needs to be further clarified. UDP-glucuronosyltransferase 1A1 (UGT1A1) is a key enzyme for bilirubin metabolism. In this study, C57BL/6J mice were injected intraperitoneally with lipopolysaccharide (LPS). LPS suppresses mouse hepatic UGT1A1 gene expression, leading to the increases of total bilirubin and unconjugated bilirubin. Furthermore, human hepatic UGT1A1 gene expression is inhibited in Huh7 and HepG2 cells in response to LPS stimulation. We analyzed the upstream promiter region of human UGT1A1 gene using Transcriptional Regulatory Element Database. A novel NF-κB-binding site (-725/-716) in human UGT1A1 promoter region was determined using electrophoretic mobility shift assay and chromatin immunoprecipitation. We showed that NF-κB activation is associated with down-regulation of UGT1A1 gene expression in Huh7 and HepG2 cells in response to LPS stimulation. Moreover, we further demonstrate that LPS suppresses human hepatic UGT1A1 gene expression through directly binding of NF-κB to this novel identified NF-κB-binding site (-725/-716) in the upstream promoter region of human UGT1A1 gene. This study may partly explain the molecular pathogenesis of inflammation-associated hyperbilirubinemia. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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