title: Association of histone deacetylase with COUP-TF in tumorigenic Ad12-transformed cells and its potential role in shut-off of MHC class I transcription.
abstract: Chicken ovalbumin upstream promoter-transcription factor (COUP-TF) is an orphan nuclear receptor that represses transcription of many genes. In adenovirus type 12 (Ad12) transformed cells, a high level of binding activity of COUP-TF to the major histocompatibility complex (MHC) class I enhancer correlates with the down-regulation of class I transcription, which, in turn, contributes to tumorigenesis. The mechanism by which COUP-TF represses transcription has yet to be elucidated. Here we show that COUP-TF represses transcription through its association with histone deacetylase. This was demonstrated using reciprocal binding assays that determined that the interaction between COUP-TF and histone deacetylase requires the COUP-TF C-terminal repression domain. Moreover, a histone deacetylase enzymatic activity was found to be associated with COUP-TF in Ad12-transformed cells. Transfection experiments further revealed that exogenous histone deacetylase facilitates transcriptional repression by COUP-TF. Also, supershift assays suggest that the transcriptional corepressor N-CoR, which is known to associate with histone deacetylases, is a part of the COUP-TF complex bound to the MHC class I enhancer R2 site. Finally, we provide evidence that inhibition of histone deacetylases relieves the repression of MHC class I expression in Ad12-transformed cells. Taken together these results support the notion that deacetylation of histones, mediated through COUP-TF, serves to down-regulate MHC class I transcription in Ad12-transformed cells.
authors.affiliation: Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Smirnov
authors.forename: S
authors.initials: S
authors.lastname: Hou
authors.forename: R P
authors.initials: RP
authors.lastname: Ricciardi
mesh_terms: D000260:Adenoviruses, Human / Q000235:genetics*; D000818:Animals; D001665:Binding Sites; D051838:COUP Transcription Factor I; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral; D005805:Genes, MHC Class I / Q000235:genetics*; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism* / Q000502:physiology*; D007739:L Cells; D051379:Mice; D010446:Peptide Fragments / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics* / Q000502:physiology*
chemical_list: D051838:COUP Transcription Factor I; D004268:DNA-Binding Proteins; D056572:Histone Deacetylase Inhibitors; C497590:Nr2f1 protein, mouse; D010446:Peptide Fragments; D014157:Transcription Factors; D006655:Histone Deacetylases