Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 4 de 4
Filter
Add more filters










Database
Language
Publication year range
1.
RNA ; 13(10): 1675-92, 2007 Oct.
Article in English | MEDLINE | ID: mdl-17684232

ABSTRACT

Unraveling the molecular basis of the life cycle of hepatitis C virus (HCV), a prevalent agent of human liver disease, entails the identification of cell-encoded factors that participate in the replication of the viral RNA genome. This study provides evidence that the so-called NF/NFAR proteins, namely, NF90/NFAR-1, NF110/NFAR-2, NF45, and RNA helicase A (RHA), which mostly belong to the dsRBM protein family, are involved in the HCV RNA replication process. NF/NFAR proteins were shown to specifically bind to replication signals in the HCV genomic 5' and 3' termini and to promote the formation of a looplike structure of the viral RNA. In cells containing replicating HCV RNA, the generally nuclear NF/NFAR proteins accumulate in the cytoplasmic viral replication complexes, and the prototype NFAR protein, NF90/NFAR-1, stably interacts with a viral protein. HCV replication was inhibited in cells where RNAi depleted RHA from the cytoplasm. Likewise, HCV replication was hindered in cells that contained another NF/NFAR protein recruiting virus. The recruitment of NF/NFAR proteins by HCV is assumed to serve two major purposes: to support 5'-3' interactions of the viral RNA for the coordination of viral protein and RNA synthesis and to weaken host-defense mechanisms.


Subject(s)
Hepacivirus/metabolism , RNA, Viral/metabolism , Virus Replication , Base Sequence , Cell Nucleus/chemistry , Hepacivirus/chemistry , Humans , Molecular Sequence Data , RNA, Untranslated/chemistry , RNA, Untranslated/metabolism , RNA, Viral/chemistry , Viral Proteins/metabolism
2.
RNA ; 10(10): 1637-52, 2004 Oct.
Article in English | MEDLINE | ID: mdl-15383680

ABSTRACT

The genomes of positive-strand RNA viruses strongly resemble cellular mRNAs. However, besides operating as a messenger to generate the virus-encoded proteins, the viral RNA serves also as a template during replication. A central issue of the viral life cycle, the coordination of protein and RNA synthesis, is yet poorly understood. Examining bovine viral diarrhea virus (BVDV), we report here on the role of the variable 3'V portion of the viral 3' nontranslated region (3'NTR). Genetic studies and structure probing revealed that 3'V represents a complex RNA motif that is composed of synergistically acting sequence and structure elements. Correct formation of the 3'V motif was shown to be an important determinant of the viral RNA replication process. Most interestingly, we found that a proper conformation of 3'V is required for accurate termination of translation at the stop-codon of the viral open reading frame and that efficient termination of translation is essential for efficient replication of the viral RNA. Within the viral 3'NTR, the complex 3'V motif constitutes also the binding site of recently characterized cellular host factors, the so-called NFAR proteins. Considering that the NFAR proteins associate also with the 5'NTR of the BVDV genome, we propose a model where the viral 3'NTR has a bipartite functional organization: The conserved 3' portion (3'C) is part of the nascent replication complex; the variable 5' portion (3'V) is involved in the coordination of the viral translation and replication. Our data suggest the accuracy of translation termination as a sophisticated device determining viral adaptation to the host.


Subject(s)
Diarrhea Viruses, Bovine Viral/genetics , Diarrhea Viruses, Bovine Viral/metabolism , RNA, Viral/biosynthesis , RNA, Viral/genetics , 3' Untranslated Regions , Animals , Base Sequence , Cattle , Cell Line , Diarrhea Viruses, Bovine Viral/physiology , Models, Biological , Molecular Sequence Data , Mutagenesis, Site-Directed , Nucleic Acid Conformation , Peptide Chain Termination, Translational , Protein Biosynthesis , RNA, Viral/chemistry , Virus Replication
3.
Biochem Biophys Res Commun ; 311(3): 672-7, 2003 Nov 21.
Article in English | MEDLINE | ID: mdl-14623324

ABSTRACT

Recently, a benzo-1,2,4-thiadiazine was shown to be a potent, specific inhibitor of the hepatitis C virus (HCV) RNA polymerase [J. Biol. Chem. 277 (2002) 32327]. Herein, we present several lines of evidence to demonstrate that thiadiazine compound 4 (C(21)H(21)N(3)O(4)S) is highly synergistic with interferon-alpha (IFN-alpha) and disrupts HCV replicon RNA synthesis with a distinct kinetic profile. A time course analysis after a single treatment with 5 microM compound 4 showed a loss of viral RNA consistent with replicon RNA half-life, suggesting inhibition of 90% of ongoing or newly initiated replicative intermediates. This finding is consistent with the mechanism of action recently reported for compound 4, an RNA synthesis initiation inhibitor [J. Biol. Chem. 278 (2003) 16602]. Further, unlike IFN-alpha, an immediate reduction of HCV replicon RNA synthesis was apparent upon addition of compound 4. Treatment with IFN-alpha showed a delay of approximately 4h prior to inhibition of viral RNA replication, consistent with its signaling kinetics.


Subject(s)
Antiviral Agents/pharmacokinetics , Hepacivirus/genetics , Nucleic Acid Synthesis Inhibitors/pharmacokinetics , RNA/metabolism , Thiadiazines/pharmacokinetics , Cell Line , Cell Line, Tumor , Dose-Response Relationship, Drug , Humans , Inhibitory Concentration 50 , Interferon-alpha/metabolism , Kinetics , Models, Statistical , Reverse Transcriptase Polymerase Chain Reaction , Time Factors
4.
EMBO J ; 22(21): 5655-65, 2003 Nov 03.
Article in English | MEDLINE | ID: mdl-14592965

ABSTRACT

A major issue of current virology concerns the characterization of cellular proteins that operate as functional components of the viral multiplication process. Here we describe a group of host factors designated as 'NFAR proteins' that are recruited by the replication machinery of bovine viral diarrhea virus, a close relative of the human pathogen hepatitis C virus. The NFAR proteins associate specifically with both the termini of the viral RNA genome involving regulatory elements in the 5' and 3' non-translated regions. Modification of the protein interaction sites in the 3' non-translated region yielded viral RNAs that were replication deficient. Viral replication was also inhibited by RNAi approaches that reduced the concentration of RNA helicase A, a member of the NFAR group, in the host cell's cytoplasm. Further experimental data suggest that NFAR proteins mediate a circular conformation of the viral genome that may be important for the coordination of translation and replication. Because NFAR proteins are presumed components of the antiviral response, we suspect that viral recruitment may also serve to weaken cellular defense mechanisms.


Subject(s)
Diarrhea Viruses, Bovine Viral/physiology , Phosphoproteins , RNA-Binding Proteins/physiology , 3' Untranslated Regions , Animals , Base Sequence , Binding Sites , Cattle , Diarrhea Viruses, Bovine Viral/genetics , Diarrhea Viruses, Bovine Viral/growth & development , Genome, Viral , HeLa Cells , Humans , Models, Biological , Molecular Sequence Data , Nuclear Factor 90 Proteins , Nucleic Acid Conformation , RNA Interference , RNA, Viral/chemistry , RNA, Viral/genetics , RNA, Viral/metabolism , RNA-Binding Proteins/isolation & purification , Virus Replication/physiology
SELECTION OF CITATIONS
SEARCH DETAIL
...