Project description:The liver-specific microRNA, miR-122, is an essential host factor for replication of hepatitis C virus (HCV), an important infectious cause of chronic liver disease and hepatocellular carcinoma. miR-122 stabilizes the positive-strand HCV RNA genome and promotes viral RNA synthesis by binding two closely spaced sites (S1 and S2) near the 5’ end of the genome in association with Ago2. Ago2 is essential for both host factor activities, but whether other host proteins are involved is unknown. Using a quantitative proteomics approach, we identified TNRC6A (GW182) and its paralogs (TNRC6B and TNRC6C), as functionally important components of the miR-122/Ago2 host factor complex binding HCV RNA. Depletion of any two TNRC6 proteins reduced HCV replication in Huh-7.5 cells,but did not reduce viral RNA stability or translational activity, but rather dampened miR-122 stimulation of viral RNA synthesis. However, TNRC6 depletion had no effect on replication of HCV in which S2 was mutated so that miR-122 binds only S1, whereas it significantly enhanced replication when S1 was mutated and only S2 bound by miR-122. Consistent with this, we found that TNRC6 proteins preferentially associate with the S1 site, and that the association of Ago2 with S2 is increased in TNRC6-depleted cells. Collectively, these data suggest a model in which TNRC6 proteins, which are known to interact with Ago2, preferentially direct the miR-122/Ago2 complex to S1 while restricting its association with S2, thereby fine tuning the spatial organization of miR-122/Ago2 complexes bound to the viral RNA.

2019-04-24 | PXD013054 | Pride

Hepatitis C virus functionally sequesters miR-122 [RNA-Seq]

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.

2015-01-06 | E-GEOD-64677 | biostudies-arrayexpress

MicroRNA-122 supports robust innate immunity in hepatocytes by targeting the RTKs/STAT3 signaling pathway

Project description:MicroRNA-122 (miR-122) is the most abundant microRNA in hepatocytes and a central player in liver biology and disease. Herein, we report a previously unknown role for miR-122 in hepatocyte intrinsic innate immunity. Restoring miR-122 levels in hepatoma cells markedly enhanced the activation of interferons (IFNs) in response to a variety of viral nucleic acids or simulations, especially of hepatitis C virus RNA and poly (I:C). Mechanistically, miR-122 down-regulated the phosphorylation (Tyr705) of STAT3 and thereby removed the negative regulation of STAT3 on IFN-signaling. While STAT3 represses IFN expression by inhibiting interferon regulatory factor 1 (IRF1); miR-122 targets MERTK, FGFR1 and IGF1R, three receptor tyrosine kinases (RTKs) that directly promote STAT3 phosphorylation. This work identifies a miR-122–RTKs/STAT3–IRF1–IFNs regulatory circuitry, which may play a pivotal role in regulating hepatocyte innate immunity. These findings renewed our knowledge about miR-122’s function and have important implications for treating hepatitis viruses. We used microarrays to analyze which genes were down-regulated by miR-122.

2019-02-02 | GSE99663 | GEO

Hepatitis C virus functionally sequesters miR-122 [m15 vs Mock CLIP]

2015-01-06 | GSE64678 | GEO

Hepatitis C virus functionally sequesters miR-122 [RNA-Seq]

2015-01-06 | GSE64677 | GEO