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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.

Pubmed ID: 11003653


  • O'Neill DW
  • Schoetz SS
  • Lopez RA
  • Castle M
  • Rabinowitz L
  • Shor E
  • Krawchuk D
  • Goll MG
  • Renz M
  • Seelig HP
  • Han S
  • Seong RH
  • Park SD
  • Agalioti T
  • Munshi N
  • Thanos D
  • Erdjument-Bromage H
  • Tempst P
  • Bank A


Molecular and cellular biology

Publication Data

October 30, 2000

Associated Grants

  • Agency: NIDDK NIH HHS, Id: DK25274
  • Agency: NHLBI NIH HHS, Id: HL28381
  • Agency: NCI NIH HHS, Id: P30 CA08748

Mesh Terms

  • Adenosine Triphosphatases
  • Aging
  • Animals
  • Autoantigens
  • Chromatin
  • DNA
  • DNA Helicases
  • DNA-Binding Proteins
  • Gene Expression Regulation
  • Globins
  • Histone Deacetylases
  • Histones
  • Humans
  • Ikaros Transcription Factor
  • Leukemia, Erythroblastic, Acute
  • Macromolecular Substances
  • Mi-2 Nucleosome Remodeling and Deacetylase Complex
  • Mice
  • Mice, Transgenic
  • Nuclear Proteins
  • Precipitin Tests
  • Protein Binding
  • Sin3 Histone Deacetylase and Corepressor Complex
  • Substrate Specificity
  • Transcription Factors
  • Tumor Cells, Cultured
  • Zinc Fingers