title: NCoR1 mediates papillomavirus E8;E2C transcriptional repression.
abstract: The papillomavirus E2 open reading frame encodes the full-length E2 protein as well as an alternatively spliced product called E8;E2C. E8;E2C has been best studied for the high-risk human papillomaviruses, where it has been shown to regulate viral genome levels and, like the full-length E2 protein, to repress transcription from the viral promoter that directs the expression of the viral E6 and E7 oncogenes. The repression function of E8;E2C is dependent on the 12-amino-acid N-terminal sequence from the E8 open reading frame (ORF). In order to understand the mechanism by which E8;E2C mediates transcriptional repression, we performed an unbiased proteomic analysis from which we identified six high-confidence candidate interacting proteins (HCIPs) for E8;E2C; the top two are NCoR1 and TBLR1. We established an interaction of E8;E2C with an NCoR1/HDAC3 complex and demonstrated that this interaction requires the wild-type E8 open reading frame. Small interfering RNA (siRNA) knockdown studies demonstrated the involvement of NCoR1/HDAC3 in the E8;E2C-dependent repression of the viral long control region (LCR) promoter. Additional genetic work confirmed that the papillomavirus E2 and E8;E2C proteins repress transcription through distinct mechanisms.
authors.affiliation: Department of Pathology, Harvard Medical School, New Research Building, Room 950, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
authors.forename: Maria L C
authors.initials: ML
authors.lastname: Powell
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Smith
authors.forename: Mathew E
authors.initials: ME
authors.lastname: Sowa
authors.forename: J Wade
authors.initials: JW
authors.lastname: Harper
authors.forename: Thomas
authors.initials: T
authors.lastname: Iftner
authors.forename: Frank
authors.initials: F
authors.lastname: Stubenrauch
authors.forename: Peter M
authors.initials: PM
authors.lastname: Howley
mesh_terms: D002460:Cell Line; D015967:Gene Expression Regulation, Viral; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006801:Humans; D008954:Models, Biological; D056971:Nuclear Receptor Co-Repressor 1 / Q000378:metabolism*; D027383:Papillomaviridae / Q000502:physiology*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: C539127:NCOR1 protein, human; D056971:Nuclear Receptor Co-Repressor 1; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D014764:Viral Proteins