Requirement of an E1A-sensitive coactivator for long-range transactivation by the beta-globin locus control region.
Four erythroid-specific DNase I-hypersensitive sites at the 5'-end of the beta-globin locus confer high-level transcription to the beta-globin genes. To identify coactivators that mediate long-range transactivation by this locus control region (LCR), we assessed the influence of E1A, an inhibitor of the CBP/p300 histone acetylase, on LCR function. E1A strongly inhibited transactivation of Agamma- and beta-globin promoters by the HS2, HS2-HS3, and HS1-HS4 subregions of the LCR in human K562 and mouse erythroleukemia cells. Short- and long-range transactivation mediated by the LCR were equally sensitive to E1A. The E1A sensitivity was apparent in transient and stable transfection assays, and E1A inhibited expression of the endogenous gamma-globin genes. Only sites for NF-E2 within HS2 were required for E1A sensitivity in K562 cells, and E1A abolished transactivation mediated by the activation domain of NF-E2. E1A mutants defective in CBP/p300 binding only weakly inhibited HS2-mediated transactivation, whereas a mutant defective in retinoblastoma protein binding strongly inhibited transactivation. Expression of CBP/p300 potentiated HS2-mediated transactivation. Moreover, expression of GAL4-CBP strongly increased transactivation of a reporter containing HS2 with a GAL4 site substituted for the NF-E2 sites. Thus, we propose that a CBP/p300-containing coactivator complex is the E1A-sensitive factor important for LCR function.
Forsberg
E C
EC
Department of Pharmacology, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
Johnson
K
K
Zaboikina
T N
TN
Mosser
E A
EA
Bresnick
E H
EH
D000123:Acetyltransferases / Q000378:metabolism; D017500:Adenovirus E1A Proteins / Q000378:metabolism* / Q000494:pharmacology*; D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism; D050881:E1A-Associated p300 Protein; D050981:Erythroid-Specific DNA-Binding Factors; D005914:Globins / Q000235:genetics*; D051548:Histone Acetyltransferases; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000235:genetics / Q000378:metabolism; D019901:Locus Control Region; D051379:Mice; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors*; D016133:Polymerase Chain Reaction; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000037:antagonists & inhibitors*; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D017500:Adenovirus E1A Proteins; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; C494692:NFE2 protein, human; C494693:Nfe2 protein, mouse; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D005914:Globins; D000123:Acetyltransferases; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse; D051548:Histone Acetyltransferases