A novel estrogen receptor alpha-associated protein alters receptor-deoxyribonucleic acid interactions and represses receptor-mediated transcription.
Estrogen receptor alpha (ER alpha) serves as a ligand-activated transcription factor, turning on transcription of estrogen-responsive genes in target cells. Numerous regulatory proteins interact with the receptor to influence ER alpha-mediated transactivation. In this study, we have identified pp32, which interacts with the DNA binding domain of ER alpha when the receptor is free, but not when it is bound to an estrogen response element. Coimmunoprecipitation experiments demonstrate that endogenously expressed pp32 and ER alpha from MCF-7 breast cancer cells interact. Although pp32 substantially enhances the association of the receptor with estrogen response element-containing DNA, overexpression of pp32 in MCF-7 cells decreases transcription of an estrogen-responsive reporter plasmid. pp32 Represses p300-mediated acetylation of ER alpha and histones in vitro and inhibits acetylation of ER alpha in vivo. pp32 Also binds to other nuclear receptors and inhibits thyroid hormone receptor beta-mediated transcription. Taken together, our studies provide evidence that pp32 plays a role in regulating transcription of estrogen-responsive genes by modulating acetylation of histones and ER alpha and also influences transcription of other hormone-responsive genes as well.
Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, 524 Burrill Hall, 407 South Goodwin Avenue, Urbana, Illinois 61801, USA.
Margaret A
MA
Loven
Roger E
RE
Davis
Carol D
CD
Curtis
Nemone
N
Muster
John R
JR
Yates
Ann M
AM
Nardulli
D000107:Acetylation / Q000187:drug effects; D001667:Binding, Competitive; D045744:Cell Line, Tumor; D004247:DNA / Q000378:metabolism; D015536:Down-Regulation; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006657:Histones / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D009687:Nuclear Proteins / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D010750:Phosphoproteins / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D025941:Protein Interaction Mapping; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic
D047628:Estrogen Receptor alpha; D006657:Histones; D009687:Nuclear Proteins; D010750:Phosphoproteins; D018160:Receptors, Cytoplasmic and Nuclear; D015534:Trans-Activators; D004247:DNA