BRG1 directly regulates nucleosome structure and chromatin looping of the alpha globin locus to activate transcription.
Alpha globin expression must be regulated properly to prevent the occurrence of alpha-thalassemias, yet many questions remain unanswered regarding the mechanism of transcriptional activation. Identifying factors that regulate chromatin structure of the endogenous alpha globin locus in developing erythroblasts will provide important mechanistic insight. Here, we demonstrate that the BRG1 catalytic subunit of SWI/SNF-related complexes co-immunoprecipitates with GATA-1 and EKLF in murine fetal liver cells in vivo and is recruited to the far-upstream major-regulatory element (MRE) and alpha2 promoter. Furthermore, based on our analysis of Brg1(null/ENU1) mutant mice, BRG1 regulates DNase I sensitivity, H3ac, and H3K4me2 but not CpG methylation at both sites. Most importantly, BRG1 is required for chromatin loop formation between the MRE and alpha2 promoter and for maximal RNA Polymerase II occupancy at the alpha2 promoter. Consequently, Brg1 mutants express alpha globin mRNA at only 5-10% of wild-type levels and die at mid-gestation. These data identify BRG1 as a chromatin-modifying factor required for nucleosome remodeling and transcriptional activation of the alpha globin locus. These data also demonstrate that chromatin looping between the MRE and alpha2 promoter is required as part of the transcriptional activation mechanism.
Kim
Shin-Il
SI
Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, Medical Sciences Center, Madison, WI, USA.
Bresnick
Emery H
EH
Bultman
Scott J
SJ
D000818:Animals; D002843:Chromatin / Q000737:chemistry*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D003850:Deoxyribonuclease I; D044127:Epigenesis, Genetic; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009707:Nucleosomes / Q000737:chemistry*; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000378:metabolism; D020218:Response Elements; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D055542:alpha-Globins / Q000235:genetics* / Q000378:metabolism
D002843:Chromatin; D009687:Nuclear Proteins; D009707:Nucleosomes; D014157:Transcription Factors; D055542:alpha-Globins; D012319:RNA Polymerase II; D003850:Deoxyribonuclease I; C513194:Smarca4 protein, mouse; D004265:DNA Helicases
Mol Cell Biol. 2002 Jan;22(1):161-70
11739731
Genes Dev. 1990 Sep;4(9):1588-601
2253879
Oncogene. 2007 Oct 15;26(47):6777-94
17934485
EMBO J. 1992 Dec;11(12):4565-72
1425590
Mol Cell Biol. 2006 Jul;26(13):5096-105
16782894
Proc Natl Acad Sci U S A. 1980 Nov;77(11):6634-8
6935674
EMBO J. 2007 Apr 18;26(8):2041-51
17380126
Blood. 1995 Aug 1;86(3):1202-11
7620173
Nat Struct Mol Biol. 2004 Jan;11(1):73-80
14718926
Mol Cell. 2003 Feb;11(2):377-89
12620226
Blood. 1995 Jul 15;86(2):766-75
7606006
Blood. 2002 Nov 15;100(10):3450-6
12393394
Blood. 2003 Apr 1;101(7):2842-9
12517812
Cell. 2007 Jan 12;128(1):197-209
17218265
Blood. 2006 May 1;107(9):3811-2
16627766
Mol Cell. 2005 Feb 4;17(3):453-62
15694345
Annu Rev Biochem. 2002;71:755-81
12045110
Mol Cell. 2000 Feb;5(2):387-93
10882079
Genes Dev. 2004 Oct 15;18(20):2485-90
15489291
Cell. 1995 Mar 24;80(6):837-45
7697714
Cell. 1980 Apr;19(4):947-58
6247075
EMBO J. 2006 Aug 9;25(15):3586-95
16858401
Development. 2008 Feb;135(3):493-500
18094026
Blood Cells Mol Dis. 2008 Mar-Apr;40(2):166-73
18029204
Proc Natl Acad Sci U S A. 1998 Mar 3;95(5):2061-6
9482838
Mol Biol Evol. 2002 Apr;19(4):416-21
11919282
Mol Cell. 2001 Aug;8(2):465-71
11545748
Genes Dev. 2006 Jun 1;20(11):1447-57
16705039
Blood. 2007 Dec 15;110(13):4503-10
17715390
Genomics. 1995 Oct 10;29(3):679-89
8575760
Genes Dev. 2005 Dec 1;19(23):2849-61
16287714
EMBO J. 1987 Apr;6(4):999-1004
3595568
Nat Genet. 2004 Oct;36(10):1065-71
15361872
Genome Res. 2004 Apr;14(4):623-30
15060003
Genes Dev. 2000 Oct 1;14(19):2441-51
11018012
Proc Natl Acad Sci U S A. 1999 Oct 26;96(22):12311-5
10535918
Nat Immunol. 2008 Jul;9(7):785-93
18500344
J Mol Biol. 2001 Oct 12;313(1):27-34
11601844
Mol Cell Biol. 2001 Apr;21(7):2413-22
11259590
Cell. 2007 Jul 27;130(2):373-84
17662950
Proc Natl Acad Sci U S A. 2001 Oct 9;98(21):12114-9
11593024
EMBO J. 2002 Oct 1;21(19):5245-54
12356740
Proc Natl Acad Sci U S A. 2009 Feb 17;106(7):2259-64
19171905
EMBO J. 2004 Jul 21;23(14):2841-52
15215894
Biochem J. 2006 Oct 15;399(2):297-304
16800816
Mol Cell Biol. 2007 Jun;27(12):4551-65
17438135
Biochemistry. 2007 Feb 27;46(8):2100-10
17274598
Cell Res. 2006 Apr;16(4):347-55
16617330
Cell. 2009 Jan 23;136(2):200-6
19167321
Exp Cell Res. 2005 Sep 10;309(1):174-84
16002065
Cell. 1998 Oct 2;95(1):93-104
9778250
Annu Rev Biochem. 2002;71:247-73
12045097
Genes Dev. 2006 Sep 1;20(17):2349-54
16951251
Mol Cell. 2003 May;11(5):1311-22
12769854
Nat Genet. 2000 Apr;24(4):368-71
10742099