p300 mediates functional synergism between AF-1 and AF-2 of estrogen receptor alpha and beta by interacting directly with the N-terminal A/B domains.
Estrogen receptor (ER) alpha and beta mediate estrogen actions in target cells through transcriptional control of target gene expression. For 17beta-estradiol-induced transactivation, the N-terminal A/B domain (AF-1) and the C-terminal E/F domain (AF-2) of ERs are required. Ligand binding is considered to induce functional synergism between AF-1 and AF-2, but the molecular mechanism remains unknown. To clarify this synergism, we studied the role of reported AF-2 coactivators, p300/CREB binding protein, steroid receptor coactivator-1/transcriptional intermediary factor-2 (SRC-1/TIF2) family proteins and thyroid hormone receptor-associated protein-220/(vitamin D3 receptor-interacting protein- 205-(TRAP220/DRIP205) on the AF-1 activity in terms of synergism with the AF-2 function. We found that neither any of the SRC-1/TIF2 family coactivators nor TRAP220/DRIP205 is potent, whereas p300 potentiates the AF-1 function of both human ERalpha and human ERbeta. Direct interactions of p300 with the A/B domains of ERalpha and ERbeta were observed in an in vitro glutathione S-transferase pull-down assay in accordance with the interactions in yeast and mammalian two-hybrid assays. Furthermore, mutations in the p300 binding sites (56-72 amino acids in ERalpha and 62-72 amino acids in ERbeta) in the A/B domains caused a reduction in ligand-induced transactivation functions of both ERalpha and ERbeta. Thus, these findings indicate that ligand-induced functional synergism between AF-1 and AF-2 is mediated through p300 by its direct binding to the A/B regions of ERalpha and ERbeta.
Kobayashi
Y
Y
Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan.
Kitamoto
T
T
Masuhiro
Y
Y
Watanabe
M
M
Kase
T
T
Metzger
D
D
Yanagisawa
J
J
Kato
S
S
D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D017930:Genes, Reporter; D051548:Histone Acetyltransferases; D006801:Humans; D056913:Mediator Complex Subunit 1; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D056920:Nuclear Receptor Coactivator 1; D051958:Nuclear Receptor Coactivator 2; D011485:Protein Binding; D011960:Receptors, Estrogen / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics; D014162:Transfection
D002352:Carrier Proteins; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; C538855:MED1 protein, human; D056913:Mediator Complex Subunit 1; C498001:NCOA2 protein, human; D009687:Nuclear Proteins; D051958:Nuclear Receptor Coactivator 2; D011960:Receptors, Estrogen; D015534:Trans-Activators; D014157:Transcription Factors; D051548:Histone Acetyltransferases; C538859:NCOA1 protein, human; D056920:Nuclear Receptor Coactivator 1