title: Hepatitis C virus NS5A physically associates with p53 and regulates p21/waf1 gene expression in a p53-dependent manner.
abstract: We have previously demonstrated that hepatitis C virus (HCV) NS5A protein promotes cell growth and transcriptionally regulates the p21/waf1 promoter, a downstream effector gene of p53. In this study, we investigated the molecular mechanism of NS5A-mediated transcriptional repression of p21/waf1. We observed that transcriptional repression of the p21/waf1 gene by NS5A is p53 dependent by using p53 wild-type (+/+) and null (-/-) cells. Interestingly, p53-mediated transcriptional activation from a synthetic promoter containing multiple p53 binding sites (PG13-LUC) was abrogated following expression of HCV NS5A. Additional studies using pull-down experiments, in vivo coimmunoprecipitation, and mammalian two-hybrid assays demonstrated that NS5A physically associates with p53. Confocal microscopy revealed sequestration of p53 in the perinuclear membrane and colocalization with NS5A in transfected HepG2 and Saos-2 cells. Together these results suggest that an association of NS5A and p53 allows transcriptional modulation of the p21/waf1 gene and may contribute to HCV-mediated pathogenesis.
authors.affiliation: Department of Pathology, Saint Louis University, St. Louis, Missouri 63104, USA.
authors.forename: M
authors.initials: M
authors.lastname: Majumder
authors.forename: A K
authors.initials: AK
authors.lastname: Ghosh
authors.forename: R
authors.initials: R
authors.lastname: Steele
authors.forename: R
authors.initials: R
authors.lastname: Ray
authors.forename: R B
authors.initials: RB
authors.lastname: Ray
mesh_terms: D016475:3T3 Cells; D000818:Animals; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D011401:Promoter Regions, Genetic; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*; D017361:Viral Nonstructural Proteins / Q000502:physiology*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D016159:Tumor Suppressor Protein p53; D017361:Viral Nonstructural Proteins; C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase