Increased Phosphoenolpyruvate Carboxykinase Gene Expression and Steatosis during Hepatitis C Virus Subgenome Replication: ROLE OF NONSTRUCTURAL COMPONENT 5A AND CCAAT/ENHANCER-BINDING PROTEIN β*
| Autor: | Qadri, Ishtiaq, Choudhury, Mahua, Rahman, Shaikh Mizanoor, Knotts, Trina A., Janssen, Rachel C., Schaack, Jerome, Iwahashi, Mieko, Puljak, Livia, Simon, Francis R., Kilic, Gordan, Fitz, J. Gregory, Friedman, Jacob E. |
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| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
Genome
Viral Hepacivirus Viral Nonstructural Proteins Virus Replication Genes Reporter Cell Line Tumor Animals Humans Insulin Cyclic AMP Response Element-Binding Protein Luciferases Promoter Regions Genetic Forkhead Box Protein O1 CCAAT-Enhancer-Binding Protein-beta Secretory Vesicles Gluconeogenesis virus diseases Molecular Bases of Disease Forkhead Transcription Factors Lipid Metabolism Rats Fatty Liver Glucose Diabetes Mellitus Type 2 Enzyme Induction Glucose-6-Phosphatase Phosphoenolpyruvate Carboxykinase (GTP) Signal Transduction |
| Popis: | Chronic hepatitis C virus (HCV) infection greatly increases the risk for type 2 diabetes and nonalcoholic steatohepatitis; however, the pathogenic mechanisms remain incompletely understood. Here we report gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK) transcription and associated transcription factors are dramatically up-regulated in Huh.8 cells, which stably express an HCV subgenome replicon. HCV increased activation of cAMP response element-binding protein (CREB), CCAAT/enhancer-binding protein (C/EBPβ), forkhead box protein O1 (FOXO1), and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and involved activation of the cAMP response element in the PEPCK promoter. Infection with dominant-negative CREB or C/EBPβ-shRNA significantly reduced or normalized PEPCK expression, with no change in PGC-1α or FOXO1 levels. Notably, expression of HCV nonstructural component NS5A in Huh7 or primary hepatocytes stimulated PEPCK gene expression and glucose output in HepG2 cells, whereas a deletion in NS5A reduced PEPCK expression and lowered cellular lipids but was without effect on insulin resistance, as demonstrated by the inability of insulin to stimulate mobilization of a pool of insulin-responsive vesicles to the plasma membrane. HCV-replicating cells demonstrated increases in cellular lipids with insulin resistance at the level of the insulin receptor, increased insulin receptor substrate 1 (Ser-312), and decreased Akt (Ser-473) activation in response to insulin. C/EBPβ-RNAi normalized lipogenic genes sterol regulatory element-binding protein-1c, peroxisome proliferator-activated receptor γ, and liver X receptor α but was unable to reduce accumulation of triglycerides in Huh.8 cells or reverse the increase in ApoB expression, suggesting a role for increased lipid retention in steatotic hepatocytes. Collectively, these data reveal an important role of NS5A, C/EBPβ, and pCREB in promoting HCV-induced gluconeogenic gene expression and suggest that increased C/EBPβ and NS5A may be essential components leading to increased gluconeogenesis associated with HCV infection. |
| Databáze: | OpenAIRE |
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