title: Bromodomain protein Brd3 associates with acetylated GATA1 to promote its chromatin occupancy at erythroid target genes.
abstract: Acetylation of histones triggers association with bromodomain-containing proteins that regulate diverse chromatin-related processes. Although acetylation of transcription factors has been appreciated for some time, the mechanistic consequences are less well understood. The hematopoietic transcription factor GATA1 is acetylated at conserved lysines that are required for its stable association with chromatin. We show that the BET family protein Brd3 binds via its first bromodomain (BD1) to GATA1 in an acetylation-dependent manner in vitro and in vivo. Mutation of a single residue in BD1 that is involved in acetyl-lysine binding abrogated recruitment of Brd3 by GATA1, demonstrating that acetylation of GATA1 is essential for Brd3 association with chromatin. Notably, Brd3 is recruited by GATA1 to both active and repressed target genes in a fashion seemingly independent of histone acetylation. Anti-Brd3 ChIP followed by massively parallel sequencing in GATA1-deficient erythroid precursor cells and those that are GATA1 replete revealed that GATA1 is a major determinant of Brd3 recruitment to genomic targets within chromatin. A pharmacologic compound that occupies the acetyl-lysine binding pockets of Brd3 bromodomains disrupts the Brd3-GATA1 interaction, diminishes the chromatin occupancy of both proteins, and inhibits erythroid maturation. Together these findings provide a mechanism for GATA1 acetylation and suggest that Brd3 "reads" acetyl marks on nuclear factors to promote their stable association with chromatin.
authors.affiliation: Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
authors.forename: Janine M
authors.initials: JM
authors.lastname: Lamonica
authors.forename: Wulan
authors.initials: W
authors.lastname: Deng
authors.forename: Stephan
authors.initials: S
authors.lastname: Kadauke
authors.forename: Amy E
authors.initials: AE
authors.lastname: Campbell
authors.forename: Roland
authors.initials: R
authors.lastname: Gamsjaeger
authors.forename: Hongxin
authors.initials: H
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: Cheng
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Billin
authors.forename: Ross C
authors.initials: RC
authors.lastname: Hardison
authors.forename: Joel P
authors.initials: JP
authors.lastname: Mackay
authors.forename: Gerd A
authors.initials: GA
authors.lastname: Blobel
mesh_terms: D000107:Acetylation; D000818:Animals; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D041905:Erythroid Cells / Q000166:cytology*; D050982:GATA1 Transcription Factor / Q000737:chemistry* / Q000378:metabolism; D005786:Gene Expression Regulation; D006410:Hematopoiesis; D006657:Histones / Q000737:chemistry*; D051379:Mice; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry*; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D014157:Transcription Factors; D000092468:Bromodomain Containing Proteins
chemical_list: D002843:Chromatin; D050982:GATA1 Transcription Factor; D006657:Histones; D009687:Nuclear Proteins; D014157:Transcription Factors; C518476:Brd3 protein, mouse; D000092468:Bromodomain Containing Proteins; C494689:Gata1 protein, mouse