scholarly journals Role of Oxysterol Binding Protein in Hepatitis C Virus infection

2009 ◽  
Vol 83 (18) ◽  
pp. 9237-9246 ◽  
Author(s):  
Yutaka Amako ◽  
Ali Sarkeshik ◽  
Hak Hotta ◽  
John Yates ◽  
Aleem Siddiqui
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Golgi Apparatus ◽  
Binding Protein ◽  
Hcv Rna ◽  
Ph Domain ◽  
Particle Release ◽  
Oxysterol Binding Protein ◽  
Rnp Complex

ABSTRACT Hepatitis C virus (HCV) RNA genome replicates within the ribonucleoprotein (RNP) complex in the modified membranous structures extended from endoplasmic reticulum. A proteomic analysis of HCV RNP complexes revealed the association of oxysterol binding protein (OSBP) as one of the components of these complexes. OSBP interacted with the N-terminal domain I of the HCV NS5A protein and colocalized to the Golgi compartment with NS5A. An OSBP-specific short hairpin RNA that partially downregulated OSBP expression resulted in a decrease of the HCV particle release in culture supernatant with little effect on viral RNA replication. The pleckstrin homology (PH) domain located in the N-terminal region of OSBP targeted this protein to the Golgi apparatus. OSBP deletion mutation in the PH (ΔPH) domain failed to localize to the Golgi apparatus and inhibited the HCV particle release. These studies suggest a possible functional role of OSBP in the HCV maturation process.

scholarly journals Genotype Dependence of Hepatitis C Virus Load Measurement in Commercially Available Quantitative Assays

1999 ◽  
Vol 37 (8) ◽  
pp. 2525-2532 ◽  
Author(s):  
Janet Mellor ◽  
Anna Hawkins ◽  
Peter Simmonds
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Narrow Range ◽  
Antiviral Treatment ◽  
Hcv Rna ◽  
Clinical Specimens ◽  
Rna Transcripts ◽  
Relative Quantitation ◽  
Version 2.0

Standardization and genotype independence of methods used to quantify hepatitis C virus (HCV) RNA in clinical specimens are necessary for accurate assessment of the role of HCV quantitation as a prognostic marker for HCV infection and monitoring of the response to antiviral treatment. Commercially available methods used to measure HCV loads include PCR-based (Roche Monitor) and hybridization-based (Quantiplex bDNA-2) methods. Recently, a new version of the Roche Monitor assay (version 2.0) has become available; it has been modified to achieve more equal quantitation of different HCV genotypes. Consistent with previous reports, Roche Monitor version 1.0 substantially underestimated concentrations of RNA transcripts of types 2b, 3a, 4a, 5a, and 6a and virus loads in individuals infected with genotypes 2 to 6 relative to reference tests. However, version 2.0 achieved equivalent quantitation of each genotype over a narrow quantitative range (103 to 5 × 105 copies of RNA/ml) but significantly underestimated RNA concentrations above this range. The assay showed an equivalent inability to quantify high levels of HCV RNA in plasma samples, and this was responsible for the falsely narrow range of virus loads detected in HCV-infected individuals. In contrast, the Chiron bDNA-2 assay could only measure RNA concentrations in the upper quantitative range (2 × 105 to 5 × 107 copies of RNA/ml) but showed equivalent sensitivity for genotypes 1 to 5; however, concentrations of type 6a RNA transcripts and virus loads in clinical specimens from individuals infected with type 6a were underestimated by a factor of 2 to 4. Differences were observed between PCR- and hybridization-based assays in their relative quantitation of HCV RNA transcripts and HCV genomic RNA, which may cause problems with the use of transcripts for interassay calibration.

scholarly journals Hepatitis C Virus (HCV) Constitutively Activates STAT-3 via Oxidative Stress: Role of STAT-3 in HCV Replication

2005 ◽  
Vol 79 (3) ◽  
pp. 1569-1580 ◽  
Author(s):  
Gulam Waris ◽  
James Turkson ◽  
Tarek Hassanein ◽  
Aleem Siddiqui
Keyword(s):  
Oxidative Stress ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Hcv Rna ◽  
Pyrrolidine Dithiocarbamate ◽  
Constitutive Activation ◽  
Mitogen Activated Protein

ABSTRACT The hepatitis C virus (HCV) causes chronic hepatitis, which often results in liver cirrhosis and hepatocellular carcinoma. We have previously shown that HCV nonstructural proteins induce activation of STAT-3 via oxidative stress and Ca2+ signaling (G. Gong, G. Waris, R. Tanveer, and A. Siddiqui, Proc. Natl. Acad. Sci. USA 98:9599-9604, 2001). In this study, we focus on the signaling pathway leading to STAT-3 activation in response to oxidative stress induced by HCV translation and replication activities. Here, we demonstrate the constitutive activation of STAT-3 in HCV replicon-expressing cells. The HCV-induced STAT-3 activation was inhibited in the presence of antioxidant (pyrrolidine dithiocarbamate) and Ca2+ chelators (BAPTA-AM and TMB-8). Previous studies have shown that maximum STAT-3 transactivation requires Ser727 phosphorylation in addition to tyrosine phosphorylation. Using a series of inhibitors and dominant negative mutants, we show that HCV-induced activation of STAT-3 is mediated by oxidative stress and influenced by the activation of cellular kinases, including p38 mitogen-activated protein kinase, JNK, JAK-2, and Src. Our results also suggest a potential role of STAT-3 in HCV RNA replication. We also observed the constitutive activation of STAT-3 in the liver biopsy of an HCV-infected patient. These studies provide an insight into the mechanisms by which HCV induces intracellular events relevant to liver pathogenesis associated with the viral infection.

scholarly journals The Role of the RNA-RNA Interactome in the Hepatitis C Virus Life Cycle

2020 ◽  
Vol 21 (4) ◽  
pp. 1479 ◽  
Author(s):  
Cristina Romero-López ◽  
Alfredo Berzal-Herranz
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Long Range ◽  
Genomic Sequence ◽  
Rna Virus ◽  
Hcv Rna ◽  
Structural Elements ◽  
Control Translation ◽  
Rna Interaction

RNA virus genomes are multifunctional entities endowed with conserved structural elements that control translation, replication and encapsidation, among other processes. The preservation of these structural RNA elements constraints the genomic sequence variability. The hepatitis C virus (HCV) genome is a positive, single-stranded RNA molecule with numerous conserved structural elements that manage different steps during the infection cycle. Their function is ensured by the association of protein factors, but also by the establishment of complex, active, long-range RNA-RNA interaction networks-the so-called HCV RNA interactome. This review describes the RNA genome functions mediated via RNA-RNA contacts, and revisits some canonical ideas regarding the role of functional high-order structures during the HCV infective cycle. By outlining the roles of long-range RNA-RNA interactions from translation to virion budding, and the functional domains involved, this work provides an overview of the HCV genome as a dynamic device that manages the course of viral infection.

Suggested role of the Golgi apparatus and endoplasmic reticulum for crucial sites of hepatitis C virus replication in human lymphoblastoid cells infected in vitro

2003 ◽  
Vol 70 (1) ◽  
pp. 31-41 ◽  
Author(s):  
Annalucia Serafino ◽  
Maria Beatrice Valli ◽  
Federica Andreola ◽  
Annalisa Crema ◽  
Giampietro Ravagnan ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Golgi Apparatus ◽  
Virus Replication ◽  
Lymphoblastoid Cells

scholarly journals Diminished viral replication and compartmentalization of hepatitis C virus in hepatocellular carcinoma tissue

2016 ◽  
Vol 113 (5) ◽  
pp. 1375-1380 ◽  
Author(s):  
Djamila Harouaka ◽  
Ronald E. Engle ◽  
Kurt Wollenberg ◽  
Giacomo Diaz ◽  
Ashley B. Tice ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Population ◽  
Hcv Rna ◽  
Carcinoma Tissue ◽  
Insight Into ◽  
Hepatocellular Carcinoma Tissue ◽  
Comprehensive Study

Analysis of hepatitis C virus (HCV) replication and quasispecies distribution within the tumor of patients with HCV-associated hepatocellular carcinoma (HCC) can provide insight into the role of HCV in hepatocarcinogenesis and, conversely, the effect of HCC on the HCV lifecycle. In a comprehensive study of serum and multiple liver specimens from patients with HCC who underwent liver transplantation, we found a sharp and significant decrease in HCV RNA in the tumor compared with surrounding nontumorous tissues, but found no differences in multiple areas of control non-HCC cirrhotic livers. Diminished HCV replication was not associated with changes in miR-122 expression. HCV genetic diversity was significantly higher in livers containing HCC compared with control non-HCC cirrhotic livers. Tracking of individual variants demonstrated changes in the viral population between tumorous and nontumorous areas, the extent of which correlated with the decline in HCV RNA, suggesting HCV compartmentalization within the tumor. In contrast, compartmentalization was not observed between nontumorous areas and serum, or in controls between different areas of the cirrhotic liver or between liver and serum. Our findings indicate that HCV replication within the tumor is restricted and compartmentalized, suggesting segregation of specific viral variants in malignant hepatocytes.

scholarly journals Critical Role of Cyclophilin A and Its Prolyl-Peptidyl Isomerase Activity in the Structure and Function of the Hepatitis C Virus Replication Complex

2009 ◽  
Vol 83 (13) ◽  
pp. 6554-6565 ◽  
Author(s):  
Zhe Liu ◽  
Feng Yang ◽  
Jason M. Robotham ◽  
Hengli Tang
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Critical Role ◽  
Cyclophilin A ◽  
Hcv Rna ◽  
Nonstructural Proteins ◽  
Ppiase Activity ◽  
Replication Complex ◽  
And Function

ABSTRACT Replication of hepatitis C virus (HCV) RNA occurs on intracellular membranes, and the replication complex (RC) contains viral RNA, nonstructural proteins, and cellular cofactors. We previously demonstrated that cyclophilin A (CyPA) is an essential cofactor for HCV infection and the intracellular target of cyclosporine's anti-HCV effect. Here we investigate the mechanism by which CyPA facilitates HCV replication. Cyclosporine treatment specifically blocked the incorporation of NS5B into the RC without affecting either the total protein level or the membrane association of the protein. Other nonstructural proteins or viral RNAs in the RC were not affected. NS5B from the cyclosporine-resistant replicon was resistant to this disruption of RC incorporation. We also isolated membrane fractions from both naïve and HCV-positive cells and found that CyPA is recruited into membrane fractions in HCV-replicating cells via an interaction with RC-associated NS5B, which is sensitive to cyclosporine treatment. Finally, we introduced point mutations in the prolyl-peptidyl isomerase (PPIase) motif of CyPA and demonstrated a critical role of this motif in HCV replication in cDNA rescue experiments. We propose a model in which the incorporation of the HCV polymerase into the RC depends on its interaction with a cellular chaperone protein and in which cyclosporine inhibits HCV replication by blocking this critical interaction and the PPIase activity of CyPA. Our results provide a mechanism of action for the cyclosporine-mediated inhibition of HCV and identify a critical role of CyPA's PPIase activity in the proper assembly and function of the HCV RC.

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