title: Hepatitis C virus NS3 protein can activate the Notch-signaling pathway through binding to a transcription factor, SRCAP.
abstract: Persistent infections of hepatitis C virus (HCV) are known to be a major risk factor for causing hepatocellular carcinomas. Nonstructural protein 3 (NS3) of HCV has serine protease and RNA helicase domains, and is essential for the viral replication. Further, NS3 is also considered to be involved in the development of HCV-induced hepatocellular carcinomas. In this report, we focus on the function of NS3 protein, and propose a novel possible molecular mechanism which is thought to be related to the tumorigenesis caused by the persistent infection of HCV. We identified SRCAP (Snf2-related CBP activator protein) as a NS3 binding protein using yeast two-hybrid screening, and a co-immunoprecipitation assay demonstrated that NS3 can bind to SRCAP in mammalian cells. The results of a reporter gene assay using Hes-1 promoter which is known to be a target gene activated by Notch, indicate that NS3 and SRCAP cooperatively activate the Hes-1 promoter in Hep3B cells. In addition, we show in this report that also p400, which is known as a protein closely resembling SRCAP, would be targeted by NS3. NS3 exhibited binding activity also to the 1449-1808 region of p400 by a co-immunoprecipitation assay, and further the activation of the Notch-mediated transcription of Hes-1 promoter by NS3 decreased significantly by the combined silencing of SRCAP and p400 mRNA using short hairpin RNA. These results suggest that the HCV NS3 protein is involved in the activation of the Notch-signaling pathway through the targeting to both SRCAP and p400.
authors.affiliation: Department of Bioresources, Hokkaido University Research Center for Zoonosis Control, Sapporo, Hokkaido, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Iwai
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Takegami
authors.forename: Takuya
authors.initials: T
authors.lastname: Shiozaki
authors.forename: Tadaaki
authors.initials: T
authors.lastname: Miyazaki
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D004265:DNA Helicases / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D020868:Gene Silencing; D057809:HEK293 Cells; D006367:HeLa Cells; D016174:Hepacivirus; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D020014:K562 Cells; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D051881:Receptor, Notch1 / Q000378:metabolism*; D000071656:Receptor, Notch3; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D000072056:Transcription Factor HES-1; D015533:Transcriptional Activation / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D000251:Adenosine Triphosphatases; D051792:Basic Helix-Loop-Helix Proteins; D004265:DNA Helicases; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D010446:Peptide Fragments; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D051881:Receptor, Notch1; D000071656:Receptor, Notch3; D051880:Receptors, Notch; D000072056:Transcription Factor HES-1; D017361:Viral Nonstructural Proteins; C499374:NOTCH3 protein, human; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C078493:HES1 protein, human; C119652:SRCAP protein, human; C498558:EP400 protein, human