title: Regulation of hepatitis C virus replication by nuclear translocation of nonstructural 5A protein and transcriptional activation of host genes.
abstract: Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is involved in regulating viral replication through its direct interaction with the HCV RNA-dependent RNA polymerase. NS5A also alters infected cell metabolism through complex interactions with numerous host cell proteins. NS5A has furthermore been suggested to act as a transcriptional activator, although the impact on viral replication is unclear. To study this, HCV NS5A variants were amplified from hepatic tissue from an HCV-infected patient, and their abilities to activate gene transcription were analyzed in a single-hybrid yeast (Saccharomyces cerevisiae) model. Different variants isolated from the same patient displayed different transactivational activities. When these variants were inserted into the HCV subgenomic replicon system, they demonstrated various levels of RNA replication, which correlated with their transactivational activities. We showed that the C-terminal fragment of NS5A was localized to the nucleus and that a functional NS5A nuclear localization signal and cellular caspase activity were required for this process. Furthermore, nuclear localization of NS5A was necessary for viral replication. Finally, we demonstrate that nuclear NS5A binds to host cell promoters of several genes previously identified as important for efficient HCV RNA replication, inducing their transcription. Taken together, these results demonstrate a new mechanism by which HCV modulates its cellular environment, thereby enhancing viral replication.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale U955, Université Paris-Est, Créteil, France.
authors.forename: Muhammad Ahmad
authors.initials: MA
authors.lastname: Maqbool
authors.forename: Mohamed R
authors.initials: MR
authors.lastname: Imache
authors.forename: Martin R
authors.initials: MR
authors.lastname: Higgs
authors.forename: Sophie
authors.initials: S
authors.lastname: Carmouse
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Pawlotsky
authors.forename: Hervé
authors.initials: H
authors.lastname: Lerat
mesh_terms: D000369:Aged, 80 and over; D002467:Cell Nucleus / Q000737:chemistry; D016174:Hepacivirus / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D019698:Hepatitis C, Chronic / Q000821:virology; D054884:Host-Pathogen Interactions; D006801:Humans; D008297:Male; D019913:Nuclear Localization Signals; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics; D015533:Transcriptional Activation; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication; D012324:RNA-Dependent RNA Polymerase
chemical_list: D019913:Nuclear Localization Signals; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase