title: Novel regulatory role for human Acf1 in transcriptional repression of vitamin D3 receptor-regulated genes.
abstract: Hormones and vitamins play integral roles in modulating transcriptional activity of members of the nuclear hormone receptor (NR) superfamily. The nuclear receptor corepressor protein (N-CoR) is essential for the transcriptional repression by unliganded NRs. In an attempt to isolate novel components of the hormone signaling pathway, we used a yeast two-hybrid screen and identified human ATP-utilizing chromatin assembly and remodeling factor 1 (hAcf1) as an N-CoR interacting protein. A previously unrecognized function of hAcf1 in the repression of euchromatic genes in mammalian cells was found: hAcf1 plays key roles in the hormone responsiveness and in the transcriptional repression of specific class II NR-regulated genes. First, hormone treatment causes a significant release of hAcf1 from its target gene promoters. Second, hAcf1 is crucial for stabilizing the endogenous vitamin D receptor-N-CoR repression complex and N-CoR itself, in the vitamin D3-regulated IGF binding protein 3 and receptor activator of nuclear factor-kappaB ligand gene promoters, respectively. Third, RNA interference-mediated reduction of hAcf1 or vitamin D3 treatment differentially affects the histone modification profile and the histone occupancy in these genes. Together, these results establish that hAcf1 has a critical role in the transcriptional repression of specific NR-regulated genes and indicate that hAcf1 release and histone H3 and H4 eviction are novel mechanisms in hormone-induced gene activation.
authors.affiliation: Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Amy K
authors.initials: AK
authors.lastname: Ewing
authors.forename: Michelle
authors.initials: M
authors.lastname: Attner
authors.forename: Debabrata
authors.initials: D
authors.lastname: Chakravarti
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D002868:Chromosomal Proteins, Non-Histone; D015536:Down-Regulation / Q000502:physiology*; D006728:Hormones / Q000502:physiology; D006801:Humans; D018167:Receptors, Calcitriol / Q000502:physiology*; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D000092468:Bromodomain Containing Proteins
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D006728:Hormones; D018167:Receptors, Calcitriol; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; C492319:BAZ1A protein, human; D000092468:Bromodomain Containing Proteins