A WW domain-binding motif within the activation domain of the hematopoietic transcription factor NF-E2 is essential for establishment of a tissue-specific histone modification pattern.
Histone H3 methylated at lysine 4 (H3-meK4) co-localizes with hyperacetylated histones H3 and H4 in transcriptionally active chromatin, but mechanisms that establish H3-meK4 are poorly understood. Previously, we showed that the hematopoietic-specific activator NF-E2, which is required for beta-globin transcription in erythroleukemia cells, induces histone H3 hyperacetylation and H3-meK4 at the adult beta-globin genes (betamajor and betaminor). Chromatin immunoprecipitation analysis indicated that NF-E2 occupies hypersensitive site two (HS2) of the beta-globin locus control region. The mechanism of NF-E2-mediated chromatin modification was investigated by complementation analysis in NF-E2-null CB3 erythroleukemia cells. The activation domain of the hematopoietic-specific subunit of NF-E2 (p45/NF-E2) contains two WW domain-binding motifs (PXY-1 and PXY-2). PXY-1 is required for activation of beta-globin transcription. Here, we determined which step in NF-E2-dependent transactivation is PXY-1-dependent. A p45/NF-E2 mutant lacking 42 amino acids of the activation domain, including both PXY motifs, and a mutant lacking only PXY-1 were impaired in inducing histone H3 hyperacetylation, H3-meK4, and RNA polymerase II recruitment. The PXY motifs were not required for transactivation in the context of a GAL4 DNA-binding domain fusion to p45/NF-E2 in transient transfection assays. As the PXY-1 mutant occupied HS2 normally, the chromatin modification defect occurred post-DNA binding. PXY-1 was not required for recruitment of the histone acetyltransferases cAMP-responsive element-binding protein-binding protein (CBP) and p300 to HS2. These results indicate that PXY-1 confers chromatin-specific transcriptional activation via interaction with a co-regulator distinct from CBP/p300 or by regulating CBP/p300 function.
University of Wisconsin Medical School, Department of Pharmacology, Madison, Wisconsin 53706, USA.
Carol M
CM
Kiekhaefer
Meghan E
ME
Boyer
Kirby D
KD
Johnson
Emery H
EH
Bresnick
D000107:Acetylation; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D050981:Erythroid-Specific DNA-Binding Factors; D017353:Gene Deletion; D005914:Globins / Q000235:genetics; D006410:Hematopoiesis; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute; D008533:Megakaryocytes; D051379:Mice; D016296:Mutagenesis; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; D012319:RNA Polymerase II / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D006657:Histones; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; C494692:NFE2 protein, human; C494693:Nfe2 protein, mouse; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D005914:Globins; D004247:DNA; D012319:RNA Polymerase II