Regulation of hepatitis C virus by microRNA-122

2008 ◽  
Vol 36 (6) ◽  
pp. 1220-1223 ◽  
Author(s):  
Catherine L. Jopling
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Replication ◽  
Binding Site ◽  
Rna Stability ◽  
Viral Rna ◽  
Hcv Rna ◽  
Mrna Targets ◽  
Virus Rna ◽  
Regulate Protein

Most metazoan miRNAs (microRNAs) bind to sites in the 3′-UTRs (untranslated regions) of mRNA targets and negatively regulate protein synthesis. The liver-specific miR-122, however, exerts a positive effect on HCV (hepatitis C virus) RNA levels by binding directly to a site in the 5′-UTR of the viral RNA. HCV translation and RNA stability are unaffected, and therefore miR-122 is likely to act at the level of viral replication. The miR-122-binding site in HCV RNA was examined to determine whether the nature of the site is responsible for the unusual mode of action for a miRNA. When the site was placed in the 3′-UTR of a reporter mRNA, miR-122 repressed translation, and therefore the location of the miR-122-binding site dictates its effect on gene expression. Additionally, a second binding site for miR-122 was identified in the HCV 5′-UTR, and miR-122 binding to both sites in the same viral RNA was found to be necessary for viral replication. The two sites are adjacent and are separated by a short spacer, which is largely conserved between HCV genotypes. The binding site requirements for miR-122 to positively regulate HCV replication provide an insight into this unusual mode of miRNA action.

scholarly journals A Recombinant Hepatitis C Virus RNA-Dependent RNA Polymerase Capable of Copying the Full-Length Viral RNA

1999 ◽  
Vol 73 (9) ◽  
pp. 7694-7702 ◽  
Author(s):  
Jong-Won Oh ◽  
Takayoshi Ito ◽  
Michael M. C. Lai
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Rna Polymerase ◽  
Rna Synthesis ◽  
De Novo ◽  
Full Length ◽  
Viral Rna ◽  
Hcv Rna ◽  
Independent Manner ◽  
Virus Rna

ABSTRACT All of the previously reported recombinant RNA-dependent RNA polymerases (RdRp), the NS5B enzymes, of hepatitis C virus (HCV) could function only in a primer-dependent and template-nonspecific manner, which is different from the expected properties of the functional viral enzymes in the cells. We have now expressed a recombinant NS5B that is able to synthesize a full-length HCV genome in a template-dependent and primer-independent manner. The kinetics of RNA synthesis showed that this RdRp can initiate RNA synthesis de novo and yield a full-length RNA product of genomic size (9.5 kb), indicating that it did not use the copy-back RNA as a primer. This RdRp was also able to accept heterologous viral RNA templates, including poly(A)- and non-poly(A)-tailed RNA, in a primer-independent manner, but the products in these cases were heterogeneous. The RdRp used some homopolymeric RNA templates only in the presence of a primer. By using the 3′-end 98 nucleotides (nt) of HCV RNA, which is conserved in all genotypes of HCV, as a template, a distinct RNA product was generated. Truncation of 21 nt from the 5′ end or 45 nt from the 3′ end of the 98-nt RNA abolished almost completely its ability to serve as a template. Inclusion of the 3′-end variable sequence region and the U-rich tract upstream of the X region in the template significantly enhanced RNA synthesis. The 3′ end of minus-strand RNA of HCV genome also served as a template, and it required a minimum of 239 nt from the 3′ end. These data defined the cis-acting sequences for HCV RNA synthesis at the 3′ end of HCV RNA in both the plus and minus senses. This is the first recombinant HCV RdRp capable of copying the full-length HCV RNA in the primer-independent manner expected of the functional HCV RNA polymerase.

scholarly journals Regulation of Hepatitis C Virus Genome Replication by Xrn1 and MicroRNA-122 Binding to Individual Sites in the 5′ Untranslated Region

2015 ◽  
Vol 89 (12) ◽  
pp. 6294-6311 ◽  
Author(s):  
Patricia A. Thibault ◽  
Adam Huys ◽  
Yalena Amador-Cañizares ◽  
Julie E. Gailius ◽  
Dayna E. Pinel ◽  
...  
Keyword(s):  
Life Cycle ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Binding Site ◽  
Binding Sites ◽  
Untranslated Region ◽  
Rna Stability ◽  
Virus Genome ◽  
Hcv Rna ◽  
Genome Replication

ABSTRACTmiR-122 is a liver-specific microRNA (miRNA) that binds to two sites (S1 and S2) on the 5′ untranslated region (UTR) of the hepatitis C virus (HCV) genome and promotes the viral life cycle. It positively affects viral RNA stability, translation, and replication, but the mechanism is not well understood. To unravel the roles of miR-122 binding at each site alone or in combination, we employed miR-122 binding site mutant viral RNAs, Hep3B cells (which lack detectable miR-122), and complementation with wild-type miR-122, an miR-122 with the matching mutation, or both. We found that miR-122 binding at either site alone increased replication equally, while binding at both sites had a cooperative effect. Xrn1 depletion rescued miR-122-unbound full-length RNA replication to detectable levels but not to miR-122-bound levels, confirming that miR-122 protects HCV RNA from Xrn1, a cytoplasmic 5′-to-3′ exoribonuclease, but also has additional functions. In cells depleted of Xrn1, replication levels of S1-bound HCV RNA were slightly higher than S2-bound RNA levels, suggesting that both sites contribute, but their contributions may be unequal when the need for protection from Xrn1 is reduced. miR-122 binding at S1 or S2 also increased translation equally, but the effect was abolished by Xrn1 knockdown, suggesting that the influence of miR-122 on HCV translation reflects protection from Xrn1 degradation. Our results show that occupation of each miR-122 binding site contributes equally and cooperatively to HCV replication but suggest somewhat unequal contributions of each site to Xrn1 protection and additional functions of miR-122.IMPORTANCEThe functions of miR-122 in the promotion of the HCV life cycle are not fully understood. Here, we show that binding of miR-122 to each of the two binding sites in the HCV 5′ UTR contributes equally to HCV replication and that binding to both sites can function cooperatively. This suggests that active Ago2–miR-122 complexes assemble at each site and can cooperatively promote the association and/or function of adjacent complexes, similar to what has been proposed for translation suppression by adjacent miRNA binding sites. We also confirm a role for miR-122 in protection from Xrn1 and provide evidence that miR-122 has additional functions in the HCV life cycle unrelated to Xrn1. Finally, we show that each binding site may contribute unequally to Xrn1 protection and other miR-122 functions.

scholarly journals Modulation of Hepatitis C Virus RNA Abundance and the Isoprenoid Biosynthesis Pathway by MicroRNA miR-122 Involves Distinct Mechanisms

2009 ◽  
Vol 84 (1) ◽  
pp. 666-670 ◽  
Author(s):  
Kara L. Norman ◽  
Peter Sarnow
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Mevalonate Pathway ◽  
Direct Interaction ◽  
Viral Rna ◽  
Hcv Rna ◽  
Isoprenoid Metabolism ◽  
Virus Rna ◽  
Intermediate Metabolites ◽  
Rna Accumulation

ABSTRACT MicroRNA 122 (miR-122) promotes hepatitis C virus (HCV) RNA abundance through a direct interaction with the viral RNA and stimulates the mevalonate pathway in the animal liver. We found that overexpression of miR-122 enhanced viral RNA accumulation without affecting genes in the mevalonate pathway, such as the 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) gene. However, inhibition of miR-122 decreased both HCV RNA and HMGCR RNA with little effects on the rates of HCV and HMGCR RNA synthesis. Loss of HCV RNA could not be restored by isoprenoid intermediate metabolites. Overall, these findings suggest that miR-122 modulates viral RNA abundance independently of its effect on isoprenoid metabolism.

scholarly journals The 3′-Untranslated Region of Hepatitis C Virus RNA Enhances Translation from an Internal Ribosomal Entry Site

1998 ◽  
Vol 72 (11) ◽  
pp. 8789-8796 ◽  
Author(s):  
Takayoshi Ito ◽  
Stanley M. Tahara ◽  
Michael M. C. Lai
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Untranslated Region ◽  
Rna Stability ◽  
Encephalomyocarditis Virus ◽  
Hcv Rna ◽  
Globin Mrna ◽  
Entry Site ◽  
Polypyrimidine Tract Binding Protein ◽  
Virus Rna

ABSTRACT Translation of most eukaryotic mRNAs and many viral RNAs is enhanced by their poly(A) tails. Hepatitis C virus (HCV) contains a positive-stranded RNA genome which does not have a poly(A) tail but has a stretch of 98 nucleotides (X region) at the 3′-untranslated region (UTR), which assumes a highly conserved stem-loop structure. This X region binds a polypyrimidine tract-binding protein (PTB), which also binds to the internal ribosome entry site (IRES) in HCV 5′-UTR. These RNA-protein interactions may regulate its translation. We generated a set of HCV RNAs differing only in their 3′-UTRs and compared their translation efficiencies. HCV RNA containing the X region was translated three- to fivefold more than the corresponding RNAs without this region. Mutations that abolished PTB binding in the X region reduced, but did not completely abolish, enhancement in translation. The X region also enhanced translation from another unrelated IRES (from encephalomyocarditis virus RNA), but did not affect the 5′-end-dependent translation of globin mRNA in either monocistronic or bicistronic RNAs. It did not appear to affect RNA stability. The free X region added in trans, however, did not enhance translation, indicating that the translational enhancement by the X region occurs only in cis. These results demonstrate that the highly conserved 3′ end of HCV RNA provides a novel mechanism for enhancement of HCV translation and may offer a target for antiviral agents.

scholarly journals Clinical application of the Quantiplex HCV RNA 2.0 and Amplicor HCV Monitor assays for quantifying serum hepatitis C virus RNA

1999 ◽  
Vol 52 (11) ◽  
pp. 807-811 ◽  
Author(s):  
M. L. Yu ◽  
W. L. Chuang ◽  
S. C. Chen ◽  
Z. Y. Lin ◽  
M. Y. Hsieh ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Clinical Application ◽  
Hcv Rna ◽  
Serum Hepatitis ◽  
Hepatitis C Virus Rna ◽  
Virus Rna

scholarly journals Regulating Intracellular Antiviral Defense and Permissiveness to Hepatitis C Virus RNA Replication through a Cellular RNA Helicase, RIG-I

2005 ◽  
Vol 79 (5) ◽  
pp. 2689-2699 ◽  
Author(s):  
Rhea Sumpter ◽  
Yueh-Ming Loo ◽  
Eileen Foy ◽  
Kui Li ◽  
Mitsutoshi Yoneyama ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Infections ◽  
Cultured Cells ◽  
Rna Replication ◽  
Rna Helicase ◽  
Hcv Rna ◽  
Helicase Domain ◽  
Replication Studies ◽  
Virus Rna

ABSTRACT Virus-responsive signaling pathways that induce alpha/beta interferon production and engage intracellular immune defenses influence the outcome of many viral infections. The processes that trigger these defenses and their effect upon host permissiveness for specific viral pathogens are not well understood. We show that structured hepatitis C virus (HCV) genomic RNA activates interferon regulatory factor 3 (IRF3), thereby inducing interferon in cultured cells. This response is absent in cells selected for permissiveness for HCV RNA replication. Studies including genetic complementation revealed that permissiveness is due to mutational inactivation of RIG-I, an interferon-inducible cellular DExD/H box RNA helicase. Its helicase domain binds HCV RNA and transduces the activation signal for IRF3 by its caspase recruiting domain homolog. RIG-I is thus a pathogen receptor that regulates cellular permissiveness to HCV replication and, as an interferon-responsive gene, may play a key role in interferon-based therapies for the treatment of HCV infection.

THE QSAR RESEARCH ON AURONE INHIBITORS OF HEPATITIS C VIRUS RNA-DEPENDENT RNA POLYMERASE BY APPLYING MULTI-DIMENSIONAL SCALING METHOD

2013 ◽  
Vol 06 (01) ◽  
pp. 1250062
Author(s):  
YONG-HONG HU ◽  
BAO-HUA ZHANG
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Rna Polymerase ◽  
Hcv Rna ◽  
Training Set ◽  
Rna Dependent Rna Polymerase ◽  
Dimensional Scaling ◽  
Naturally Occurring ◽  
Virus Rna ◽  
Multi Dimensional Scaling

In this paper, we take naturally occurring 2-benzylidenebenzofuran-3-ones (aurones) inhibitors of hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp) as an example to study the Multi-dimensional scaling (MDS) method for structure-activity relationship. By analyzing training set molecules, our MDS method combined with a PROXSCAL algorithm can predict inhibitory activity of most compounds correctly. Thus, a new sample's activity can be estimated and judged conveniently, and whether it should be synthesized can be known. The MDS method is applicable to optimize the structure for a compound and to provide suggestions for drug design.

scholarly journals Hepatitis C Virus Regulates its Replication by Maturing miR-122 Through Akt-Dependent Phosphorylation of KSRP

2019 ◽  
Author(s):  
Camille Baudesson ◽  
Céline Amadori ◽  
Hassan Danso ◽  
Flora Donati ◽  
Quentin Nevers ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Direct Interaction ◽  
Micro Rna ◽  
Host Protein ◽  
Hcv Rna ◽  
Serine Residue ◽  
Reciprocal Regulation ◽  
Mrna Targets ◽  
Infected Cells

AbstractThe liver-specific micro-RNA-122 (miR-122) is required for the replication of hepatitis C virus (HCV). The direct interaction between miR-122 and the 5’ untranslated region of the HCV genome promotes viral replication and protects HCV RNA from degradation. Because HCV RNA is its own substrate for replication, infected cells are submitted to the sequestration of increasing levels of miR-122 and to global de-repression of host miR-122 mRNA targets. Whether and how HCV regulates miR-122 maturation to create an environment favorable to its replication remains unexplored. We discovered that Akt-dependent phosphorylation of KSRP host protein at Serine residue 193 is essential for miR-122 maturation in hepatocytes. Moreover, we showed the existence of a reciprocal regulation loop where HCV replication can modulate the proviral effect mediated by KSRP-dependent maturation of miR-122. These data support a mechanism by which HCV regulates the expression of miR-122 by hijacking KSRP, thereby fueling its own replication.

scholarly journals Characterization of Occult Hepatitis C Virus (Hcv) Infection among Hemodialysis Patient

2017 ◽  
Vol 16 (1) ◽  
Author(s):  
Siti Nurul Fazlin Abdul Rahman ◽  
Hairul Aini binti Hamzah ◽  
Mohammed Imad Mustafa ◽  
Mohamed Hadzri Hasmoni
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Hemodialysis Patients ◽  
Hcv Infection ◽  
Viral Rna ◽  
Cell Counting ◽  
Hcv Rna ◽  
Viral Rnas ◽  
Occult Hepatitis ◽  
Occult Hepatitis C

Introduction: The existence of new entity called occult hepatitis C virus (HCV) has become a raising and escalating concern among healthcare professionals worldwide. It is defined by the presence of viral RNA in liver and/or peripheral blood mononuclear cells (PBMCs) within non HCV-infected patients. Previous study had shown the occult HCV is infectious and capable of transmitting the virus to another host. Till today, HCV infection remains common among hemodialysis patients despite having the best preventive plans. Because of this, there is a significant concern about the source of viral transmission. The aim of the study was to identify and characterize occult HCV infection in PBMC sample of hemodialysis patients. This was an observational and cross sectional study. Materials and method: PBMCs were isolated from the whole blood using Ficoll-gradient centrifugation technique. The PBMCs were then subjected for cell counting and stored in -70O C until further used. HCV RNA were extracted from these cells and viral RNA were subjected for molecular assays, immune cells analysis and cells culture. Results: PBMCs were isolated from eleven (11) study patients and five (5) anti-HCV positive (control) patients. By using automated flow cytometry, PBMCs of each sample were counted and the average number of cells obtained range from 2x104 to 5x106 cells/ ml. Viral RNAs were extracted and quantitatively measured by using NanoDrop Spectrophotometers. The viral RNAs concentration obtained were between 24.7 and 258.9 ng/ml. The RNAs would be subjected for purification (ethanol precipitation) and further assays. Conclusion: The final findings might contribute to the clinical management of dialysis patients.

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