Effect of heptitis C virus core protein on cellular gene expression: specific inhibition of cyclooxygenase 2.
ABSTRACT Hepatitis C virus (HCV) core protein plays a significant role in the alteration of cellular gene expression. We expressed HCV core protein using a tetracycline-inducible expression system in HeLa cell lines. Profiles of gene expression in cells expressing the HCV core protein were compared with those in control cells by use of microarray analysis. Cells expressing the HCV core protein showed 86 down-regulated and 41 up-regulated genes, compared with control cells. One gene affected was cyclooxygenase 2 (COX-2). Levels of both COX-2 RNA and the Cox-2 protein were significantly inhibited after the expression of HCV core protein in HeLa cells. Similar results were obtained in hepatoma cells and in a functional assay that measured the production of the Cox-2 protein in response to a mitogenic stimulus. The inhibition of the Cox-2 protein could serve as a means of muting the cellular inflammatory response during HCV infection. Correlation of these findings with analysis of clinical specimens from chronically infected patients should lend further significance to the down-regulation of the inflammatory response via Cox-2.
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ABSTRACT: Hepatitis C is a major health problem affecting more than 200 million individuals in world including Pakistan. Current treatment regimen consisting of interferon alpha and ribavirin does not always succeed to eliminate virus completely from the patient's body. Interferon induced antiviral protein kinase R (PKR) has a role in the hepatitis C virus (HCV) treatment as dsRNA activated PKR has the capacity to phosphorylate the serine and threonine of E2 protein and dimerization viral RNA. E2 gene of hepatitis C virus (HCV) genotype 1 has an active role in IFN resistance. E2 protein inhibits and terminates the kinase activity of PKR by blocking it in protein synthesis and cell growth. This brings forward a possible relation of E2 and PKR through a mechanism via which HCV evades the antiviral effect of IFN. A hybrid in-silico and wet laboratory approach of motif prediction, evolutionary and structural anlysis has pointed out serine 75 and 277 of the HCV E2 gene as a promising candidate for the serine phosphorylation. It is proposed that serine phosphorylation of HCV E2 gene has a significant role in interferon resistance.Virology Journal 02/2011; 8:71. · 2.09 Impact Factor
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ABSTRACT: Background. Hepatitis C virus (HCV) genotype 3 is known to cause steatosis (fatty liver) that is more frequent and severe than other genotypes. We previously identified sequence elements within genotype 3 HCV Core domain 3 that were sufficient for lipid accumulation. Aims. We examined various genotype 3 Core domains for lipid droplet localization and compared the lipid droplet binding regions of domain 2 with a genotype 1 isolate. Methods. We generated HCV Core domain constructs fused with green fluorescent protein and performed immunofluorescence to visualize lipid droplets. Results. Constructs containing HCV Core domain 2 are appropriately localized to lipid droplets with varying degrees of efficiency. When compared to genotype 1, there are polymorphisms within domain 2 that do not appear to alter lipid droplet localization. Conclusions. In summary, the differences in a steatosis-associated HCV Core genotype 3 isolate do not appear to involve altered lipid droplet localization.ISRN gastroenterology. 01/2012; 2012:176728.
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ABSTRACT: The hepatitis C virus (HCV) envelope glycoproteins have been shown to cause ER stress and induce the unfolded protein response (UPR). Using a bicistronic reporter, we show that the envelope glycoproteins repressed both cap-dependent and HCV IRES-mediated translation in HeLa cells but displayed a differential repression of cap-dependent translation in Huh-7 cells. In contrast, the envelope glycoproteins repressed E2F transcriptional activity in both HeLa and Huh-7 cells and caused increased accumulation of the underphosphorylated retinoblastoma protein. Expression of the envelope glycoproteins induced eIF2alpha phosphorylation, suggesting a role of the UPR in regulating translation and E2F transcriptional activity. The envelope glycoproteins also enhanced transcriptional activity from the COX-2 promoter and endogenous COX-2 expression in HeLa cells, but not in Huh-7 cells. Together, these results suggest that the envelope glycoproteins may assume more functional roles in viral replication and host cell interactions.Archives of Virology 09/2009; 154(10):1631-40. · 2.03 Impact Factor