title: Chromatin repression by COUP-TFII and HDAC dominates activation by NF-kappaB in regulating major histocompatibility complex class I transcription in adenovirus tumorigenic cells.
abstract: In adenovirus type 12 transformed cells, the down-regulation of MHC class I transcription contributes to the tumorigenic phenotype and is solely mediated by Ad12 E1A. Previous in vitro studies with class I enhancer sequences have indicated that there is an increased binding of repressor COUP-TFII and its associated HDAC and a decreased binding of activator NF-kappaB. In this study, we used chromatin immunoprecipitation (ChIP) assay in order to determine in vivo whether these proteins regulate class I transcription by affecting chromatin. The ChIP assay revealed that there is lack of chromatin histone acetylation in the region of the class I enhancer in Ad12-transformed cells. This is regulated by histone deacetylation as it was further demonstrated in vivo that COUP-TFII and HDAC are associated with the class I enhancer chromatin. In agreement with in vitro studies, NF-kappaB could be recruited to the class I enhancer following induction by TNF-alpha. However, this enhancer-bound NF-kappaB failed to up-regulate class I expression because the class I enhancer chromatin remained repressed as a result of histone deacetylation by HDAC in association with COUP-TFII. Thus, we have demonstrated for the first time that repression of chromatin through histone deacetylation is a major mechanism in down-regulating class I transcription in Ad12-transformed cells. Finally, Ad12 E1A, a non-DNA binding protein, was shown to be present in the natural protein complex bound to the class I enhancer.
authors.affiliation: Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Biwei
authors.initials: B
authors.lastname: Zhao
authors.forename: Shihe
authors.initials: S
authors.lastname: Hou
authors.forename: Robert P
authors.initials: RP
authors.lastname: Ricciardi
mesh_terms: D000256:Adenoviridae; D017500:Adenovirus E1A Proteins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D051837:COUP Transcription Factor II; D051836:COUP Transcription Factors; D002472:Cell Transformation, Viral; D002843:Chromatin / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015536:Down-Regulation; D004742:Enhancer Elements, Genetic / Q000235:genetics; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism*; D006655:Histone Deacetylases / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D051381:Rats; D011987:Receptors, Steroid; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
chemical_list: D017500:Adenovirus E1A Proteins; D051837:COUP Transcription Factor II; D051836:COUP Transcription Factors; D002843:Chromatin; D004268:DNA-Binding Proteins; D015395:Histocompatibility Antigens Class I; D016328:NF-kappa B; C497587:Nr2f2 protein, mouse; C497588:Nr2f2 protein, rat; D011987:Receptors, Steroid; D014157:Transcription Factors; D006655:Histone Deacetylases