title: Rho GDP dissociation inhibitor alpha interacts with estrogen receptor alpha and influences estrogen responsiveness.
abstract: Estrogen receptor alpha (ER alpha) is a ligand-activated transcription factor that regulates expression of estrogen-responsive genes. Upon binding of the ligand-occupied ER alpha to estrogen response elements (EREs) in DNA, the receptor interacts with a variety of coregulatory proteins to modulate transcription of target genes. We have isolated and identified a number of proteins associated with the DNA-bound ER alpha. One of these proteins, Rho guanosine diphosphate (GDP) dissociation inhibitor alpha (RhoGDI alpha), is a negative regulator of the Rho family of GTP-binding proteins. In this study, we demonstrate that endogenously expressed RhoGDI alpha is present in the nucleus as well as the cytoplasm of MCF-7 breast cancer cells, and that RhoGDI alpha binds directly to ER alpha, alters the ER alpha-ERE interaction, and influences the ability of ER alpha to regulate transcription of a heterologous estrogen-responsive reporter plasmid in transient transfection assays as well as endogenous, estrogen-responsive genes in MCF-7 cells. Our studies suggest that, in addition to the activity of RhoGDI alpha in the cytoplasm, it also influences ER alpha signaling in the nucleus.
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Saad
authors.initials: S
authors.lastname: El Marzouk
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Schultz-Norton
authors.forename: Varsha S
authors.initials: VS
authors.lastname: Likhite
authors.forename: Ian X
authors.initials: IX
authors.lastname: McLeod
authors.forename: John R
authors.initials: JR
authors.lastname: Yates
authors.forename: Ann M
authors.initials: AM
authors.lastname: Nardulli
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D011485:Protein Binding; D020218:Response Elements; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
chemical_list: C569638:ARHGDIA protein, human; D047628:Estrogen Receptor alpha; D004967:Estrogens; D020730:Guanine Nucleotide Dissociation Inhibitors; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors