IGF2BP1 enhances HCV IRES-mediated translation initiation via the 3′UTR

Weinlich, Susan; Hüttelmaier, Stefan; Schierhorn, Angelika; Behrens, Sven-Erik; Ostareck-Lederer, Antje; Ostareck, Dirk H.

doi:10.1261/rna.1578409

Cited by 85 publications

(92 citation statements)

References 74 publications

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“…With regard to RNA binding proteins, PCBP2 and La favor genome circularization and hence replication (22,23). IGF2BP1 binds to the 5=/3= UTR, helps in recruitment of eukaryotic translation initiation factor 3 (eIF3) to the 5= UTR, and enhances IRES-mediated translation (49). DDX3X binds specifically to the HCV 3= UTR and affects lipid droplet biogenesis, virus assembly, and secretion (50).…”

Section: Discussionmentioning

confidence: 99%

HuR Displaces Polypyrimidine Tract Binding Protein To Facilitate La Binding to the 3′ Untranslated Region and Enhances Hepatitis C Virus Replication

Shwetha

Kumar

Mullick

et al. 2015

J Virol

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HuR is a ubiquitous, RNA binding protein that influences the stability and translation of several cellular mRNAs. Here, we report a novel role for HuR, as a regulator of proteins assembling at the 3= untranslated region (UTR) of viral RNA in the context of hepatitis C virus (HCV) infection. HuR relocalizes from the nucleus to the cytoplasm upon HCV infection, interacts with the viral polymerase (NS5B), and gets redistributed into compartments of viral RNA synthesis. Depletion in HuR levels leads to a significant reduction in viral RNA synthesis. We further demonstrate that the interaction of HuR with the 3= UTR of the viral RNA affects the interaction of two host proteins, La and polypyrimidine tract binding protein (PTB), at this site. HuR interacts with La and facilitates La binding to the 3= UTR, enhancing La-mediated circularization of the HCV genome and thus viral replication. In addition, it competes with PTB for association with the 3= UTR, which might stimulate viral replication. Results suggest that HuR influences the formation of a cellular/viral ribonucleoprotein complex, which is important for efficient initiation of viral RNA replication. Our study unravels a novel strategy of regulation of HCV replication through an interplay of host and viral proteins, orchestrated by HuR. IMPORTANCE Hepatitis C virus (HCV) is highly dependent on various host factors for efficient replication of the viral RNA.Here, we have shown how a host factor (HuR) migrates from the nucleus to the cytoplasm and gets recruited in the protein complex assembling at the 3= untranslated region (UTR) of HCV RNA. At the 3= UTR, it facilitates circularization of the viral genome through interaction with another host factor, La, which is critical for replication. Also, it competes with the host protein PTB, which is a negative regulator of viral replication. Results demonstrate a unique strategy of regulation of HCV replication by a host protein through alteration of its subcellular localization and interacting partners. The study has advanced our knowledge of the molecular mechanism of HCV replication and unraveled the complex interplay between the host factors and viral RNA that could be targeted for therapeutic interventions. Hepatitis C virus (HCV) was discovered in 1989 as a major cause of chronic non-A non-B hepatitis (1). HCV is an enveloped positive-strand RNA virus classified in the Hepacivirus genus within the Flaviviridae family. The single-stranded uncapped 9.6-kb RNA codes for a long polyprotein of ϳ3,000 amino acids which is then processed to structural and nonstructural proteins. The RNA genome is flanked by the 5= and 3= untranslated regions (UTRs), which are essential for translation and replication of the viral RNA. The viral proteins are synthesized by internal ribosome entry site (IRES)-mediated translation. These proteins initiate extensive remodeling of the intracellular membranes to create a detergent-resistant scaffold for viral replication, termed as the "membranous web" (2). The progeny viral genomes a...

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Section: Discussionmentioning

confidence: 99%

HuR Displaces Polypyrimidine Tract Binding Protein To Facilitate La Binding to the 3′ Untranslated Region and Enhances Hepatitis C Virus Replication

Shwetha

Kumar

Mullick

et al. 2015

J Virol

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“…EIF4B, DDX3, and ILF3 (29), which facilitate translation of the HCV genome (30,31), were upregulated. ELAVL1 (HuR) and IGF2BP1, which were downregulated, bind to the 3= UTR of HCV RNA (32), thus facilitating viral internal ribosome entry site (IRES)-dependent translation (33,34) and viral replication for HuR (35,36).…”

Section: Main Biological Processes Regulated By Hcv At the Translatiomentioning

confidence: 99%

Genome-Wide Analysis of Host mRNA Translation during Hepatitis C Virus Infection

Colman

Berre‐Scoul

Hernandez

et al. 2013

J Virol

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fIn the model of Huh-7.5.1 hepatocyte cells infected by the JFH1 hepatitis C virus (HCV) strain, transcriptomic and proteomic studies have revealed modulations of pathways governing mainly apoptosis and cell cycling. Differences between transcriptomic and proteomic studies pointed to regulations occurring at the posttranscriptional level, including the control of mRNA translation. In this study, we investigated at the genome-wide level the translational regulation occurring during HCV infection. Sucrose gradient ultracentrifugation followed by microarray analysis was used to identify translationally regulated mRNAs (mRNAs associated with ribosomes) from JFH1-infected and uninfected Huh-7.5.1 cells. Translationally regulated mRNAs were found to correspond to genes enriched in specific pathways, including vesicular transport and posttranscriptional regulation. Interestingly, the strongest translational regulation was found for mRNAs encoding proteins involved in pre-mRNA splicing, mRNA translation, and protein folding. Strikingly, these pathways were not previously identified, through transcriptomic studies, as being modulated following HCV infection. Importantly, the observed changes in host mRNA translation were directly due to HCV replication rather than to HCV entry, since they were not observed in JFH1-infected Huh-7.5.1 cells treated with a potent HCV NS3 protease inhibitor. Overall, this study highlights the need to consider, beyond transcriptomic or proteomic studies, the modulation of host mRNA translation as an important aspect of HCV infection.

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“…Of note, IGF2BP1 has previously been reported to bind and transactivate the HCV IRES (Weinlich et al 2009). Banding patterns of the most abundant proteins binding these RNAs were highly similar by Coomassie stain, suggesting that Ago2 and any associated proteins were present in relatively low abundance despite reproducible detection by Western blotting.…”

Section: Discussionmentioning

confidence: 99%

A miRNA-responsive cell-free translation system facilitates isolation of hepatitis C virus miRNP complexes

Bradrick

Nagyal

Novatt

2013

RNA

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Micro(mi)RNAs are 21-to 23-nt RNAs that regulate multiple biological processes. In association with Argonaute (Ago) proteins and other factors that form the RNA-induced silencing complex (RISC), miRNAs typically bind mRNA 3 ′ untranslated regions (UTRs) and repress protein production through antagonizing translation and transcript stability. For a given mRNA-miRNA interaction, cis-acting RNA elements and trans-acting RNA-binding proteins (RBPs) may influence mRNA fate. This is particularly true of the hepatitis C virus (HCV) genome which interacts with miR-122, an abundant liver miRNA. miR-122 binding to HCV RNA considerably stimulates virus replication in cultured cells and primates, but the mechanism(s) and associated host factors required for enhancement of HCV replication have not been fully elucidated. We recapitulated miR-122-HCV RNA interactions in a cell-free translation system derived from cells that express miR-122. Specifically, lysates produced from HEK-293 cells that inducibly transcribe and process pri-miR-122 were characterized alongside those from isogenic cells lacking miR-122 expression. We observed a stimulatory effect of miR-122 on HCV reporter mRNAs in a manner that depended on expression of miR-122 and intact target sites within the HCV 5 ′ UTR. We took advantage of this system to affinity-purify miR-122-HCV RNP complexes. Similar to functional assays, we found that association of immobilized HCV internal ribosome entry site (IRES) RNA with endogenous Ago2 requires both miR-122 expression and intact miR-122 target sites in cis. This combined approach may be generalizable to affinity purification of miRNP complexes for selected target mRNAs, allowing identification of miRNP components and RBPs that may contribute to regulation.

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IGF2BP1 enhances HCV IRES-mediated translation initiation via the 3′UTR

Cited by 85 publications

References 74 publications

HuR Displaces Polypyrimidine Tract Binding Protein To Facilitate La Binding to the 3′ Untranslated Region and Enhances Hepatitis C Virus Replication

HuR Displaces Polypyrimidine Tract Binding Protein To Facilitate La Binding to the 3′ Untranslated Region and Enhances Hepatitis C Virus Replication

Genome-Wide Analysis of Host mRNA Translation during Hepatitis C Virus Infection

A miRNA-responsive cell-free translation system facilitates isolation of hepatitis C virus miRNP complexes

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