title: GATA-1-mediated transcriptional repression yields persistent transcription factor IIB-chromatin complexes.
abstract: The hematopoietic GATA factors GATA-1 and GATA-2, which have distinct and overlapping roles to regulate blood cell development, are reciprocally expressed during erythropoiesis. GATA-1 directly represses Gata2 transcription, and reduced GATA-2 synthesis promotes red blood cell development. Gata2 repression involves "GATA switches" in which GATA-1 displaces GATA-2 from Gata2 regulatory regions. We show that extragenic GATA switch sites occupied by GATA-2 associate with as much RNA polymerase II (Pol II) and basal transcription factors as present at the active Gata2 promoters. Pol II bound to GATA switch sites in the active locus was phosphorylated on serine 5 of the carboxyl-terminal domain, indicative of elongation competence. GATA-1-mediated displacement of GATA-2 from GATA switch sites reduced Pol II recruitment to all sites except the far upstream -77-kb region. Surprisingly, TFIIB occupancy persisted at most sites upon repression. These results indicate that GATA-2-bound extragenic regulatory elements recruit Pol II, GATA-1 binding expels Pol II, and despite the persistent TFIIB-chromatin complexes, Pol II recruitment is blocked.
authors.affiliation: Molecular and Cellular Pharmacology Program, University of Wisconsin School of Medicine, Madison, Wisconsin 53706, USA.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Martowicz
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Grass
authors.forename: Emery H
authors.initials: EH
authors.lastname: Bresnick
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D004257:DNA Polymerase II / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004920:Erythropoiesis / Q000235:genetics / Q000502:physiology; D050982:GATA1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D050989:GATA2 Transcription Factor / Q000235:genetics / Q000378:metabolism; D006410:Hematopoiesis; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D035581:Transcription Factor TFIIB / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D017931:DNA Primers; D050982:GATA1 Transcription Factor; D050989:GATA2 Transcription Factor; C494689:Gata1 protein, mouse; C494712:Gata2 protein, mouse; D011993:Recombinant Fusion Proteins; D035581:Transcription Factor TFIIB; D004257:DNA Polymerase II