title: Chromatin domain activation via GATA-1 utilization of a small subset of dispersed GATA motifs within a broad chromosomal region.
abstract: Cis elements that mediate transcription factor binding are abundant within genomes, but the rules governing occupancy of such motifs in chromatin are not understood. The transcription factor GATA-1 that regulates red blood cell development binds with high affinity to GATA motifs, and initial studies suggest that these motifs are often unavailable for occupancy in chromatin. Whereas GATA-2 regulates the differentiation of all blood cell lineages via GATA motif binding, the specificity of GATA-2 chromatin occupancy has not been studied. We found that conditionally active GATA-1 (ER-GATA-1) and GATA-2 occupy only a small subset of the conserved GATA motifs within the murine beta-globin locus. Kinetic analyses in GATA-1-null cells indicated that ER-GATA-1 preferentially occupied GATA motifs at the locus control region (LCR), in which chromatin accessibility is largely GATA-1-independent. Subsequently, ER-GATA-1 increased promoter accessibility and occupied the betamajor promoter. ER-GATA-1 increased erythroid Krüppel-like factor and SWI/SNF chromatin remodeling complex occupancy at restricted LCR sites. These studies revealed three phases of beta-globin locus activation: GATA-1-independent establishment of specific chromatin structure features, GATA-1-dependent LCR complex assembly, and GATA-1-dependent promoter complex assembly. The differential utilization of dispersed GATA motifs therefore establishes spatial/temporal regulation and underlies the multistep activation mechanism.
authors.affiliation: Department of Pharmacology, University of Wisconsin Medical School, Madison, WI 53706, USA.
authors.forename: Hogune
authors.initials: H
authors.lastname: Im
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Grass
authors.forename: Kirby D
authors.initials: KD
authors.lastname: Johnson
authors.forename: Shin-Il
authors.initials: SI
authors.lastname: Kim
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Boyer
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Imbalzano
authors.forename: James J
authors.initials: JJ
authors.lastname: Bieker
authors.forename: Emery H
authors.initials: EH
authors.lastname: Bresnick
mesh_terms: D000818:Animals; D002460:Cell Line; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism*; D002875:Chromosomes / Q000378:metabolism*; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases; D050982:GATA1 Transcription Factor / Q000502:physiology*; D050989:GATA2 Transcription Factor / Q000378:metabolism; D005914:Globins / Q000235:genetics; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: D002843:Chromatin; D050982:GATA1 Transcription Factor; D050989:GATA2 Transcription Factor; C494689:Gata1 protein, mouse; C494712:Gata2 protein, mouse; D051741:Kruppel-Like Transcription Factors; D009687:Nuclear Proteins; D014157:Transcription Factors; C080774:erythroid Kruppel-like factor; D005914:Globins; D004247:DNA; C513194:Smarca4 protein, mouse; D004265:DNA Helicases