An ikaros-containing chromatin-remodeling complex in adult-type erythroid cells.
We have previously described a SWI/SNF-related protein complex (PYR complex) that is restricted to definitive (adult-type) hematopoietic cells and that specifically binds DNA sequences containing long stretches of pyrimidines. Deletion of an intergenic DNA-binding site for this complex from a human beta-globin locus construct results in delayed human gamma- to beta-globin switching in transgenic mice, suggesting that the PYR complex acts to facilitate the switch. We now show that PYR complex DNA-binding activity also copurifies with subunits of a second type of chromatin-remodeling complex, nucleosome-remodeling deacetylase (NuRD), that has been shown to have both nucleosome-remodeling and histone deacetylase activities. Gel supershift assays using antibodies to the ATPase-helicase subunit of the NuRD complex, Mi-2 (CHD4), confirm that Mi-2 is a component of the PYR complex. In addition, we show that the hematopoietic cell-restricted zinc finger protein Ikaros copurifies with PYR complex DNA-binding activity and that antibodies to Ikaros also supershift the complex. We also show that NuRD and SWI/SNF components coimmunopurify with each other as well as with Ikaros. Competition gel shift experiments using partially purified PYR complex and recombinant Ikaros protein indicate that Ikaros functions as a DNA-binding subunit of the PYR complex. Our results suggest that Ikaros targets two types of chromatin-remodeling factors-activators (SWI/SNF) and repressors (NuRD)-in a single complex (PYR complex) to the beta-globin locus in adult erythroid cells. At the time of the switch from fetal to adult globin production, the PYR complex is assembled and may function to repress gamma-globin gene expression and facilitate gamma- to beta-globin switching.
O'Neill
D W
DW
Departments of Pathology, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Schoetz
S S
SS
Lopez
R A
RA
Castle
M
M
Rabinowitz
L
L
Shor
E
E
Krawchuk
D
D
Goll
M G
MG
Renz
M
M
Seelig
H P
HP
Han
S
S
Seong
R H
RH
Park
S D
SD
Agalioti
T
T
Munshi
N
N
Thanos
D
D
Erdjument-Bromage
H
H
Tempst
P
P
Bank
A
A
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000375:Aging / Q000502:physiology; D000818:Animals; D001324:Autoantigens; D002843:Chromatin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D005914:Globins / Q000235:genetics; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D051740:Ikaros Transcription Factor; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism* / Q000473:pathology; D046911:Macromolecular Substances; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex; D051379:Mice; D008822:Mice, Transgenic; D009687:Nuclear Proteins / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D056264:Sin3 Histone Deacetylase and Corepressor Complex; D013379:Substrate Specificity; D014157:Transcription Factors / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
D001324:Autoantigens; C115323:CHD4 protein, human; D002843:Chromatin; D004268:DNA-Binding Proteins; D006657:Histones; C497239:IKZF1 protein, human; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D014157:Transcription Factors; C497238:Zfpn1a1 protein, mouse; D051740:Ikaros Transcription Factor; D005914:Globins; D004247:DNA; D006655:Histone Deacetylases; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex; D056264:Sin3 Histone Deacetylase and Corepressor Complex; D000251:Adenosine Triphosphatases; D004265:DNA Helicases