Project description:B-cell receptor (BCR) signaling is essential for the development of B-cells and plays a critical role in B-cell neoplasia. Increasing evidence indicates an association between chronic hepatitis C virus (HCV) infection and B-cell lymphoma, however, the mechanisms by which HCV causes B-cell lymphoproliferative disorder are still unclear. Herein, we demonstrate the expression of HCV viral proteins in B-cells of HCV-infected patients and show that HCV up-regulates BCR signaling in human primary B-cells. HCV nonstructural protein NS3/4A interacts with CHK2 and down-regulates its activity, modulating HuR posttranscriptional regulation of a network of target mRNAs associated with B-cell lymphoproliferative disorders. Interestingly, the BCR signaling pathway was found to have the largest number of transcripts with increased association with HuR and was up-regulated by NS3/4A. Our study reveals a previously unidentified role of NS3/4A in regulation of host BCR signaling during HCV infection, contributing to a better understanding of the molecular mechanisms underlying HCV-associated B-cell lymphoproliferative disorders.
Project description:Lambda interferons IFNL1-3 mediate antiviral immunity by inducing interferon sensitive genes (ISGs) in epithelial tissues. Contrarily, a variant creating the functional gene IFNL4 is associated with impaired clearance of hepatitis C virus (HCV) despite of higher liver expression of ISGs in untreated HCV patients. We aimed to explore IFNL4 signaling mechanism by comparing expression profiles from human hepatic cell line clones with genetic modifications influencing the ISG signaling pathway (IFNLR1/IL10R2 knockouts, IFNL4/IFNL3 expression stimulation by transfection).
Project description:The combination of peginterferon and ribavirin is the standard treatment for chronic hepatitis C. Our recent clinical study suggests that ribavirin augments the induction of interferon stimulated genes (ISGs) in patients treated for HCV infection [1]. In order to further characterize the mechanisms of action of ribavirin, we examined the effect of ribavirin treatment on ISG induction in cell culture. In addition, the effect of ribavirin on infectious HCV cell culture systems was also studied. Similar to interferon-alpha, ribavirin potently inhibits JFH-1 infection of Huh7.5.1 cells in a dose-dependent manner, which spans the physiological concentration of ribavirin in vivo. Microarray analysis and subsequent quantitative PCR assays demonstrated that ribavirin treatment resulted in the induction of a distinct set of ISGs. These ISGs, including IRF7 and IRF9 are known to play an important role in anti-HCV responses. When ribavirin is used in conjunction with interferon, induction of specific ISGs is synergistic when compared to either drug applied separately. Direct up-regulation of these antiviral genes by ribavirin is mediated by a novel mechanism different from those associated with interferon signaling and intracellular double stranded RNA sensing pathways such as RIG-I and MDA5. RNA interference studies excluded the activation of the Toll-like receptor and NF-KappaB pathways in the action of ribavirin. In conclusion, our study suggests that ribavirin, acting via a novel innate mechanism, potentiates the anti-HCV effect of interferon. Understanding the mechanism of action of ribavirin would be valuable in identifying novel antivirals. RNA from three samples were treated with Ribavirin and compared to three PBS treated samples
Project description:Gene expression profiling was carried out in Huh-7.5 cells in which miR-27a was over- or under-expressed. Transfection of cells with pre-miR-27a and pre-miR-control, or anti-miR-27a and anti-miR-control enabled down- and up-regulated genes to be determined, respectively. Replication and infectivity of the lipotrophic hepatitis C virus (HCV) is regulated by cellular lipid status. Among differentially expressed micro (mi)RNAs, we found that miR-27a was preferentially expressed in HCV-infected compared with hepatitis B virus (HBV)-infected liver. Gene expression profiling of Huh-7.5 cells showed that miR-27a regulates lipid metabolism by targeting the lipid synthetic transcriptional factor, RXRα, and the lipid transporter, ABCA1 Carrying out a Target Scan (Release 5.2) of miR-27a predicted 921 candidate target genes, and functional gene ontology enrichment analysis of these genes by MetaCore (Thomson Reuters, NY) showed that miR-27a could target the signaling pathways of cytoskeleton remodeling and lipid metabolism . To examine whether these signaling pathways were regulated by miR-27a, gene expression profiling was carried out in Huh-7.5 cells in which miR-27a was over- or under-expressed. Transfection of cells with pre-miR-27a and pre-miR-control, or anti-miR-27a and anti-miR-control enabled down- and up-regulated genes to be determined, respectively. Huh-7.5 cells with miR-27a over- or under-expressed
Project description:Gene expression profiling was carried out in Huh-7.5 cells in which miR-27a was over- or under-expressed. Transfection of cells with pre-miR-27a and pre-miR-control, or anti-miR-27a and anti-miR-control enabled down- and up-regulated genes to be determined, respectively. Replication and infectivity of the lipotrophic hepatitis C virus (HCV) is regulated by cellular lipid status. Among differentially expressed micro (mi)RNAs, we found that miR-27a was preferentially expressed in HCV-infected compared with hepatitis B virus (HBV)-infected liver. Gene expression profiling of Huh-7.5 cells showed that miR-27a regulates lipid metabolism by targeting the lipid synthetic transcriptional factor, RXRα, and the lipid transporter, ABCA1
Project description:Host cells harbor various intrinsic mechanisms to restrict viral infections as a first line of antiviral defense. Viruses have evolved various countermeasures against these antiviral mechanisms. Here we show that N-Myc Downstream-Reguated Gene 1 (NDRG1) limits productive HCV infection by inhibiting viral assembly. Interestingly, HCV infection down-regulates NDRG1 protein and mRNA expression. Loss of NDRG1 increases the size and number of lipid droplets, which are the sites of HCV assembly. HCV suppresses NDRG1 expression by up-regulating MYC, which directly inhibits the transcription of NDRG1. Up-regulation of MYC also leads to reduced expression of NDRG1-specific kinase SGK1, resulting in markedly diminished phosphorylation of NDRG1. Knockdown of MYC during HCV infection rescues NDRG1 expression and phosphorylation, suggesting that MYC regulates NDRG1 at both transcriptional and post-translational levels. Overall, our results suggest that NDRG1 restricts HCV assembly by limiting lipid droplet formation. HCV counteracts this intrinsic antiviral mechanism by down-regulating NDRG1 via a MYC-dependent mechanism.
Project description:The combination of peginterferon and ribavirin is the standard treatment for chronic hepatitis C. Our recent clinical study suggests that ribavirin augments the induction of interferon stimulated genes (ISGs) in patients treated for HCV infection [1]. In order to further characterize the mechanisms of action of ribavirin, we examined the effect of ribavirin treatment on ISG induction in cell culture. In addition, the effect of ribavirin on infectious HCV cell culture systems was also studied. Similar to interferon-alpha, ribavirin potently inhibits JFH-1 infection of Huh7.5.1 cells in a dose-dependent manner, which spans the physiological concentration of ribavirin in vivo. Microarray analysis and subsequent quantitative PCR assays demonstrated that ribavirin treatment resulted in the induction of a distinct set of ISGs. These ISGs, including IRF7 and IRF9 are known to play an important role in anti-HCV responses. When ribavirin is used in conjunction with interferon, induction of specific ISGs is synergistic when compared to either drug applied separately. Direct up-regulation of these antiviral genes by ribavirin is mediated by a novel mechanism different from those associated with interferon signaling and intracellular double stranded RNA sensing pathways such as RIG-I and MDA5. RNA interference studies excluded the activation of the Toll-like receptor and NF-KappaB pathways in the action of ribavirin. In conclusion, our study suggests that ribavirin, acting via a novel innate mechanism, potentiates the anti-HCV effect of interferon. Understanding the mechanism of action of ribavirin would be valuable in identifying novel antivirals.
Project description:Hepatitis C Virus (HCV) has a extremely narrow host cell tropism and robustly infects only very few cell lines, most importantly the human hepatoma cell line Huh7. This cell line was isolated from a 57-year old Japanese male with fulminant hepatitis. Different subclones and passages of the Huh7 cell line show up to 1000-fold differences in HCV replication efficiency (permissiveness). In this experiment, we sought to identify factors responsible for these differences by correlating gene expression from eight different uninfected Huh7 variants with their respective HCV permissiveness. HCV replication efficiency was determined using electroporation of a subgenomic luciferase reporter replicon (genotype 1b, "con1/ET") and measuring luciferase activity at 48h post transfection normalized to the input value at 4h p.t.. "Relative permissiveness" of cell lines corresponds to their replication efficiency, normalized to the efficiency in the lowest permissive cells (Huh7 p13 and p28).
Project description:Hepatitis C virus (HCV) infection is a major cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. HCV can be sensed by host innate immunity to induce expression of interferons (IFNs) and a number of antiviral effectors. HCV-encoded NS3/4 serine protease can subvert host innate immune responses by cleaving MAVS, a critical adaptor protein in the RLR-mediated IFN signaling. To study innate immunity in the context of HCV infection, we constructed Huh7-MAVSR cells which express a mutant MAVS resistant to NS3/4A cleavage. HCV infection induces robust IFN response in Huh7-MAVSR cells, providing a cellular system to study antiviral innate immune response against HCV infection. To analyze host innate antiviral effectors against HCV infection, we performed an mRNA microarray analysis in the HCV-infected Huh7-MAVSR cells.
Project description:This project enriched and identified phosphoproteins in human hepatocarcinoma 7.5.1 cell line (Huh7.5.1) upon Hepatitis C virus (HCV) infection.