title: Interaction of NCOR/SMRT Repressor Complexes with Papillomavirus E8^E2C Proteins Inhibits Viral Replication.
abstract: Infections with high-risk human papillomaviruses (HR-HPV) such as HPV16 and 31 can lead to ano-genital and oropharyngeal cancers and HPV types from the beta genus have been implicated in the development of non-melanoma skin cancer. HPV replicate as nuclear extrachromosomal plasmids at low copy numbers in undifferentiated cells. HPV16 and 31 mutants have indicated that these viruses express an E8^E2C protein which negatively regulates genome replication. E8^E2C shares the DNA-binding and dimerization domain (E2C) with the essential viral replication activator E2 and the E8 domain replaces the replication/transcription activation domain of E2. The HR-HPV E8 domain is required for inhibiting viral transcription and the replication of the viral origin mediated by viral E1 and E2 proteins. We show now that E8^E2C also limits replication of HPV1, a mu-PV and HPV8, a beta-PV, in normal human keratinocytes. Proteomic analyses identified all NCoR/SMRT corepressor complex components (HDAC3, GPS2, NCoR, SMRT, TBL1 and TBLR1) as co-precipitating host cell proteins for HPV16 and 31 E8^E2C proteins. Co-immunoprecipitation and co-localization experiments revealed that NCoR/SMRT components interact with HPV1, 8, 16 and 31 E8^E2C proteins in an E8-dependent manner. SiRNA knock-down experiments confirm that NCoR/SMRT components are critical for both the inhibition of transcription and HPV origin replication by E8^E2C proteins. Furthermore, a dominant-negative NCoR fragment activates transcription and replication only from HPV16 and 31 wt but not from mutant genomes encoding NCoR/SMRT-binding deficient E8^E2C proteins. In summary, our data suggest that the repressive function of E8^E2C is highly conserved among HPV and that it is mediated by an E8-dependent interaction with NCoR/SMRT complexes. Our data also indicate for the first time that NCoR/SMRT complexes not only are involved in inhibiting cellular and viral transcription but also in controlling the replication of HPV origins.
authors.affiliation: University Hospital Tuebingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Division of Experimental Virology, Tuebingen, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Dreer
authors.affiliation: University Hospital Tuebingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Division of Experimental Virology, Tuebingen, Germany.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Fertey
authors.affiliation: University Hospital Tuebingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Division of Experimental Virology, Tuebingen, Germany.
authors.forename: Saskia
authors.initials: S
authors.lastname: van de Poel
authors.affiliation: University Hospital Tuebingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Division of Experimental Virology, Tuebingen, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Straub
authors.affiliation: Proteome Center Tuebingen, University of Tuebingen, Tuebingen, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Madlung
authors.affiliation: Proteome Center Tuebingen, University of Tuebingen, Tuebingen, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Macek
authors.affiliation: University Hospital Tuebingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Division of Experimental Virology, Tuebingen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Iftner
authors.affiliation: University Hospital Tuebingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Division of Experimental Virology, Tuebingen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Stubenrauch
mesh_terms: D002460:Cell Line; D002853:Chromatography, Liquid; D004268:DNA-Binding Proteins / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006790:Host-Parasite Interactions / Q000502:physiology; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D015603:Keratinocytes / Q000378:metabolism / Q000821:virology; D008856:Microscopy, Fluorescence; D056971:Nuclear Receptor Co-Repressor 1 / Q000378:metabolism*; D056985:Nuclear Receptor Co-Repressor 2 / Q000378:metabolism*; D009856:Oncogene Proteins, Viral / Q000378:metabolism; D027383:Papillomaviridae; D030361:Papillomavirus Infections / Q000378:metabolism*; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053719:Tandem Mass Spectrometry; D014158:Transcription, Genetic; D014162:Transfection; D014760:Viral Fusion Proteins / Q000378:metabolism*; D014779:Virus Replication / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; C539127:NCOR1 protein, human; C539130:NCOR2 protein, human; D056971:Nuclear Receptor Co-Repressor 1; D056985:Nuclear Receptor Co-Repressor 2; D009856:Oncogene Proteins, Viral; D034741:RNA, Small Interfering; D014760:Viral Fusion Proteins; C076036:oncogene protein E2, Human papillomavirus type 1