title: The highly conserved region of the co-repressor Sin3A functionally interacts with the co-repressor Alien.
abstract: The Sin3 proteins are evolutionarily conserved co-repressors (CoR) that function as mediators of gene repression for a variety of transcriptional silencers. The paired amphipathic helices of Sin3A were identified and studied as protein-protein interacting domains. Previously we have shown the interaction of Sin3A with the CoR Alien in vivo and in vitro. Here, we show that Alien and Sin3A reside together in vivo with the vitamin D3 receptor on the human 24-hydroxylase (CYP24) promoter containing vitamin D3 response elements by chromatin immunoprecipitation. We delineated and characterized the interaction domains of Sin3A with Alien. Interestingly, the highly conserved region (HCR) of Sin3A, which has not yet been functionally characterized, interacts with Alien. The HCR encompasses only 134 amino acids, shares more than 80% identity with Sin3B and binds to the N-terminus of Alien, which harbours a transferable silencing function. Functionally, co-expression of Sin3A enhances Alien-mediated gene repression and overexpression of the HCR alone leads to the inhibition of Alien-mediated repression and to the induction of the endogenous CYP24 promoter. Our results therefore indicate a novel functional role of the Sin3 HCR and give novel insights into Alien-mediated gene repression.
authors.affiliation: Genetic Institute, Justus-Liebig-University, Heinrich-Buff-Ring 58-62, D-35392 Giessen, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Moehren
authors.forename: Uwe
authors.initials: U
authors.lastname: Dressel
authors.forename: Christina A
authors.initials: CA
authors.lastname: Reeb
authors.forename: Sami
authors.initials: S
authors.lastname: Väisänen
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Dunlop
authors.forename: Carsten
authors.initials: C
authors.lastname: Carlberg
authors.forename: Aria
authors.initials: A
authors.lastname: Baniahmad
mesh_terms: D000818:Animals; D001665:Binding Sites; D000075686:COP9 Signalosome Complex; D002460:Cell Line; D017124:Conserved Sequence; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D020868:Gene Silencing; D006801:Humans; D051379:Mice; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D018167:Receptors, Calcitriol / Q000378:metabolism; D012097:Repressor Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D056264:Sin3 Histone Deacetylase and Corepressor Complex; D013250:Steroid Hydroxylases / Q000235:genetics; D065668:Vitamin D3 24-Hydroxylase
chemical_list: C402762:COPS2 protein, human; D018167:Receptors, Calcitriol; D012097:Repressor Proteins; C099683:SIN3A transcription factor; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D065668:Vitamin D3 24-Hydroxylase; D000075686:COP9 Signalosome Complex; D056264:Sin3 Histone Deacetylase and Corepressor Complex