title: Recruitment by the Repressor Freud-1 of Histone Deacetylase-Brg1 Chromatin Remodeling Complexes to Strengthen HTR1A Gene Repression.
abstract: Five-prime repressor element under dual repression binding protein-1 (Freud-1)/CC2D1A is genetically linked to intellectual disability and implicated in neuronal development. Freud-1 represses the serotonin-1A (5-HT1A) receptor gene HTR1A by histone deacetylase (HDAC)-dependent or HDAC-independent mechanisms in 5-HT1A-negative (e.g., HEK-293) or 5-HT1A-expressing cells (SK-N-SH), respectively. To identify the underlying mechanisms, Freud-1-associated proteins were affinity-purified from HEK-293 nuclear extracts and members of the Brg1/SMARCCA chromatin remodeling and Sin3A-HDAC corepressor complexes were identified. Pull-down assays using recombinant proteins showed that Freud-1 interacts directly with the Brg1 carboxyl-terminal domain; interaction with Brg1 required the carboxyl-terminal of Freud-1. Freud-1 complexes in HEK-293 and SK-N-SH cells differed, with low levels of BAF170/SMARCC2 and BAF57/SMARCE1 in HEK-293 cells and low-undetectable BAF155/SMARCC1, Sin3A, and HDAC1/2 in SK-N-SH cells. Similarly, by quantitative chromatin immunoprecipitation, Brg1-BAF170/57 and Sin3A-HDAC complexes were observed at the HTR1A promoter in HEK-293 cells, whereas in SK-N-SH cells, Sin3A-HDAC proteins were not detected. Quantifying 5-HT1A receptor mRNA levels in cells treated with siRNA to Freud-1, Brg1, or both RNAs addressed the functional role of the Freud-1-Brg1 complex. In HEK-293 cells, 5-HT1A receptor mRNA levels were increased only when both Freud-1 and Brg1 were depleted, but in SK-N-SH cells, depletion of either protein upregulated 5-HT1A receptor RNA. Thus, recruitment by Freud-1 of Brg1, BAF155, and Sin3A-HDAC complexes appears to strengthen repression of the HTR1A gene to prevent its expression inappropriate cell types, while recruitment of the Brg1-BAF170/57 complex is permissive to 5-HT1A receptor expression. Alterations in Freud-1-Brg1 interactions in mutants associated with intellectual disability could impair gene repression leading to altered neuronal development.
authors.affiliation: Ottawa Hospital Research Institute (Neuroscience) and UOttawa Brain and Mind Research Institute, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Souslova
authors.affiliation: Ottawa Hospital Research Institute (Neuroscience) and UOttawa Brain and Mind Research Institute, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada.
authors.forename: Kim
authors.initials: K
authors.lastname: Mirédin
authors.affiliation: Ottawa Hospital Research Institute (Neuroscience) and UOttawa Brain and Mind Research Institute, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Millar
authors.affiliation: Ottawa Hospital Research Institute (Neuroscience) and UOttawa Brain and Mind Research Institute, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada. palbert@uottawa.ca.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Albert
mesh_terms: D042002:Chromatin Assembly and Disassembly / Q000502:physiology*; D004265:DNA Helicases / Q000096:biosynthesis* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D057809:HEK293 Cells; D006655:Histone Deacetylases / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D044282:Receptor, Serotonin, 5-HT1A / Q000096:biosynthesis* / Q000235:genetics; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C512283:CC2D1A protein, human; D004268:DNA-Binding Proteins; C583518:HTR1A protein, human; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D044282:Receptor, Serotonin, 5-HT1A; D006655:Histone Deacetylases; C084108:SMARCA4 protein, human; D004265:DNA Helicases
keywords: Chromatin remodeling; Gene repression; Histone deacetylase; Intellectual disability; Transcription