title: Dissecting molecular steps in chromatin domain activation during hematopoietic differentiation.
abstract: GATA factors orchestrate hematopoiesis via multistep transcriptional mechanisms, but the interrelationships and importance of individual steps are poorly understood. Using complementation analysis with GATA-1-null cells and mice containing a hypomorphic allele of the chromatin remodeler BRG1, we dissected the pathway from GATA-1 binding to cofactor recruitment, chromatin loop formation, and transcriptional activation. Analysis of GATA-1-mediated activation of the beta-globin locus, in which GATA-1 assembles dispersed complexes at the promoters and the distal locus control region (LCR), revealed molecular intermediates, including GATA-1-independent and GATA-1-containing LCR subcomplexes, both defective in promoting loop formation. An additional intermediate consisted of an apparently normal LCR complex and a promoter complex with reduced levels of total RNA polymerase II (Pol II) and Pol II phosphorylated at serine 5 of the carboxy-terminal domain. Reduced BRG1 activity solely compromised Pol II and serine 5-phosphorylated Pol II occupancy at the promoter, phenocopying the LCR-deleted mouse. These studies defined a hierarchical order of GATA-1-triggered events at a complex locus and establish a novel mechanism of long-range gene regulation.
authors: University of Wisconsin School of Medicine, Department of Pharmacology, 383 Medical Sciences Center, Madison, WI 53706, USA.
authors: Shin-Il
authors: SI
authors: Kim
authors: Scott J
authors: SJ
authors: Bultman
authors: Huie
authors: H
authors: Jing
authors: Gerd A
authors: GA
authors: Blobel
authors: Emery H
authors: EH
authors: Bresnick
mesh_terms: D000483:Alleles; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D041905:Erythroid Cells / Q000166:cytology / Q000378:metabolism; D050982:GATA1 Transcription Factor / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D005786:Gene Expression Regulation; D005914:Globins / Q000235:genetics; D006413:Hematopoietic System / Q000502:physiology*; D019901:Locus Control Region; D051379:Mice; D018345:Mice, Knockout; D008957:Models, Genetic; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000737:chemistry / Q000378:metabolism; D013696:Temperature; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D002843:Chromatin; D050982:GATA1 Transcription Factor; C494689:Gata1 protein, mouse; D009687:Nuclear Proteins; D014157:Transcription Factors; D005914:Globins; D012319:RNA Polymerase II; C513194:Smarca4 protein, mouse; D004265:DNA Helicases