Hepatitis C Virus Infection Activates a Novel Innate Pathway Involving IKKα in Lipogenesis and Viral Assembly
ABSTRACT: Hepatitis C virus interacts extensively with host factors not only to establish productive infection but also to trigger unique pathological processes. Our recent genome-wide siRNA screen demonstrated that IKKα is a critical host factor for HCV. Here we describe a novel NF-κB-independent and kinase-mediated nuclear function of IKKα in HCV assembly. HCV infection, through its 3’-untranslated region, interacts with DDX3X to activate IKKα, which translocates to the nucleus and induces a CBP/p300-mediated transcriptional program involving SREBPs. This novel innate pathway induces lipogenic genes and enhances core-associated lipid droplet formation to facilitate viral assembly. Chemical inhibitors of IKKα suppress HCV infection and IKKα-induced lipogenesis, offering a proof-of-concept approach for novel HCV therapeutic development. Our results show that HCV commands a novel mechanism to its advantage by exploiting intrinsic innate response and hijacking lipid metabolism, which likely contributes to a high chronicity rate and the pathological hallmark of steatosis in HCV infection. Cells were treated with either non-targeting control siRNA or siRNA against IKKalpha. After 72 h, cells were either mock infected or infected with HCV JFH-1 strain with the M.O.I. of 0.5.
Project description:Human hepatocyte chimeric mice were prepared and treated with hepatitis C virus (HCV) and/or interferon-alpha (IFN-α). To analyze the changes in gene expression, cDNA microarray analysis was performed with the collected human hepatocytes from the chimeric mouse livers. We consider that these results provide molecular insights into possible mechanisms used by HCV to evade innate immune responses, as well as novel therapeutic targets and a potential new indication for interferon therapy. A total of 15 human hepatocyte chimeric mice were prepared and divided into four experimental groups. Mice in group A were neither infected with HCV nor treated with IFN. Mice in group B were administered IFN-α 6 h before sacrifice but were not infected with HCV. The mice in groups C and D were both inoculated via the mouse tail vein with human serum containing HCV genotype 1b particles. At 8 weeks after inoculation, the mice in group D were administered IFN-α 6 h before sacrifice, but the mice in group C were not treated with IFN-α. The human hepatocytes in the mouse livers were collected after sacrifice and subjected to microarray analysis. After purification and reverse transcription of total RNA, cDNA was hybridized on Affymetrix GeneChip Human Gene U133 Plus 2.0 Arrays.
Project description:Hepatitis C virus uniquely requires the liver specific microRNA-122 for replication, yet global effects on endogenous miRNA targets during infection are unexplored. Here, high-throughput sequencing and crosslinking immunoprecipitation (HITS-CLIP) experiments of human Argonaute (Ago) during HCV infection showed robust Ago binding on the HCV 5’UTR, at known and predicted miR-122 sites. On the human transcriptome, we observed reduced Ago binding and functional mRNA de-repression of miR-122 targets during virus infection. This miR-122 “sponge” effect could be relieved and redirected to miR-15 targets by swapping the miRNA tropism of the virus. Single-cell expression data from reporters containing miR-122 sites showed significant de-repression during HCV infection depending on expression level and number of sites. We describe a quantitative mathematical model of HCV induced miR-122 sequestration and propose that such miR-122 inhibition by HCV RNA may result in global de-repression of host miR-122 targets, providing an environment fertile for the long-term oncogenic potential of HCV. mRNA-seq libraries were generated from mock or J6/JFH1 Clone2 infected Huh7.5 cells. Cells were infected at an MOI of 1-2 and harvested at 72 hours and 96 hours post-infection for CLIP. Libraries were generated using Illumina Truseq technology.
Project description:In this study, treatment-naive HIV, HCV mono-/co-infected individuals with CD4+ T cell counts >300/?l were recruited and their global gene expression profiles were investigated. By gene set enrichment analysis (GSEA), we revealed that gene sets of cell cycle progression, innate immune response and some transcription factors in CD4+ T cells were affected mainly by HIV; while genes associated with extracellular matrix (ECM), Beta cell development and insulin synthesis and secretion were the major targets of HCV. For metabolic pathways, it was modulated by both viruses. Besides, for the first time, our data uncovered the importance of GPCR signaling pathway during HCV, HIV infections. These data for the first time offer genetic basis for HCV/HIV mono-/co- infections, which will facilitate the understanding of the interaction of HCV/HIV in vivo and how they subvert the human gene machinery at the individual cell type level.
Project description:Hepatitis C virus (HCV), a major causative agent of acute and chronic liver disease, belongs to the Flaviviridæ family and contains a single-strand positive-sense RNA genome, which upon virus entry and uncoating, functions as mRNAs and thus can be directly translated into proteins by host cell machinery. To date the HCV origin remains unclear and HCV life cycle and pathogenesis are not enlightened processes due to the absence of HCV efficient cell cultures systems or animals models. Here we show that rabbit and hare HCV-like viruses, RHCV and HHCV respectively, are formed after the inoculation of genomic DNA in Madin-Darby bovine kidney cell line cultures. RHCV is closely related to the HCV-1a/HCV-1b genotypes and HHCV is more closely related to the HCV-1b genotype. These findings could contribute to the understanding of HCV origin as well as clarify the virus life cycle, pathogenesis, evolution and diversity.
Project description:End stage liver disease due to Hepatitis C Virus (HCV) infection is a major health concern worldwide. Liver fibrosis following chronic HCV infection plays a pivotal role in loss of liver function and end stage liver disease. However the dynamics and molecular events that lead to fibrosis in HCV infection are poorly defined. Therefore, we determined the influence of HCV infection in altering the miRNA expression levels which can modulate immune responses to HCV leading to fibrosis. Analysis of the miRNA expression profiles of HCV infected liver biopsies revealed that 45 miRNAs were differentially expressed in the HCV infected liver when compared to normal livers. In silico target prediction of these differentially expressed miRNAs indicated that their targets include chemokine/cytokine signaling, cell cycle genes and extracellular matrix protein gene expression. Gene expression profiling using whole genome microarray demonstrated that 1320 genes were differentially expressed in chronic HCV liver when compared to normal. These genes could be functionally grouped into those involved in cell cycle regulation, cytokines and chemokines expression, cell adhesion, intracellular signaling and enzymes. Further pathway analysis using GeneGo software identified cell adhesion, cytoskeleton remodeling, cytokine signaling and metabolic pathways as the major pathways activated in chronic HCV. Combinatorial target prediction analysis of miRNA expression along with gene expression analysis indicated that differentially expressed microRNAs in HCV significantly impact transforming growth factor beta (TGF-β) signaling pathway, cell adhesion (integrin expression), chemokine signaling, Notch signaling and cell-cycle( Cyclin D,K) regulation. Overall these results demonstrate that chronic HCV infection induces specific miRNA signatures that will modulate genes involved in the cytoskeletal remodeling and cytokine signaling that can promote the development of fibrosis following HCV infection. Liver biopsies from chronic HCV patients and control liver biopsies from normal subjects (donor liver prior to transplantation) were used to analyze the miRNA and gene expression profile. Patients with HBV and/or HIV were excluded from the study. This Series represents the mRNA gene expression profiling data only.
Project description:Primary human hepatocytes (PHHs) are a liver-specific cell subtype, and we have shown that these cells respond in a unique manner to the introduction of hepatitis C viral RNA (HCV vRNA) derived from different genotypes of the virus. We used microarray to analyze the transcriptional differences between the PHHs exposed to the different genotypes of HCV to further shed light on their differential effects on HCV innate immune responses in vitro HCV vRNA from either genotype 3a HCV or genotype 1a HCV was introduced into the PHH cells for 8 hours. Total RNA was then harvested to determine transcriptional differences.
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. Overall design: Huh7-MAVSR cell were infected with HCVcc at an MOI of 5 for 12, 24, 48, 72 hours. The uninfected Huh7-MAVSR cells that are similarly cultured for 72 h were used as a mock infection control. The totoal cellular RNAs were extracted and analyzed by an mRNA microarray analysis for determining genes that are differentially expressed in the HCV-infected cells.
Project description:Hepatitis C Virus is a leading cause of chronic liver disease. The identification and characterisation of key host cellular factors that play a role in the HCV replication cycle is important for the understanding of disease pathogenesis and the identification of novel anti-viral therapeutic targets. Gene expression profiling of HCV infected Huh7 cells by microarray analysis was performed to identify host cellular genes that are transcriptionally regulated by infection. The expression of host genes involved in cellular defence mechanisms (apoptosis, proliferation and anti-oxidant responses), cellular metabolism (lipid and protein metabolism) and intracellular transport (vesicle trafficking and cytoskeleton regulation) was significantly altered by HCV infection. The gene expression patterns identified provide insight into the potential mechanisms that contribute to HCV associated pathogenesis. These include an increase in pro-inflammatory and pro-apoptotic signalling and a decrease in the anti-oxidant response pathways of the infected cell. 5x105 Huh7 cells were seeded in 25cm2 culture flasks and infected in triplicate either with the genotype 2a HCV clone, JFH-1 at a multiplicity of infection (MOI) of 3 or mock infected with an equal volume of concentrated conditioned growth medium. At 6, 12, 18, 24 and 48 hours post-infection, cellular RNA was extracted using TRIzol reagent (Invitrogen). Trizol lysates were shipped to Expression Analysis (NC, USA) where RNA was purified, quality tested using the Agilent Bioanalyser and hybridised onto Human U133 Plus 2.0 Affymetrix microarray chips for fluorescence data acquisition. In summary, a total of 30 RNA samples were analysed including 3x mock infected samples taken at 6, 12, 18, 24 and 48 hours post-treatment and 3x JFH-1 infected samples taken at 6, 12, 18, 24 and 48 hours post-infection. Two samples (Mock_6hrs_1 and JFH-1_6hrs_1) did not pass our data quality control measures and were therefore excluded from the statistical analysis.