title: Direct interactions with G α i and G βγ mediate nongenomic signaling by estrogen receptor α .
abstract: Estrogen induces G protein-dependent nongenomic signaling in a variety of cell types via the activation of a plasma membrane-associated subpopulation of estrogen receptor alpha (ER alpha). Using pull-down experiments with purified recombinant proteins, we now demonstrate that ER alpha binds directly to G alpha i and G betagamma. Mutagenesis and the addition of blocking peptide reveals that this occurs via amino acids 251-260 and 271-595 of ER alpha, respectively. Studies of ER alpha complexed with heterotrimeric G proteins further show that estradiol causes the release of both G alpha i and G betagamma without stimulating GTP binding to G alpha i. Moreover, in COS-7 cells, the disruption of ER alpha-G alpha i interaction by deletion mutagenesis of ER alpha or expression of blocking peptide, as well as G betagamma sequestration with beta-adrenergic receptor kinase C terminus, prevents nongenomic responses to estradiol including src and erk activation. In endothelial cells, the disruption of ER alpha-G alpha i interaction prevents estradiol-induced nitric oxide synthase activation and the resulting attenuation of monocyte adhesion that contributes to estrogen-related cardiovascular protection. Thus, through direct interactions, ER alpha mediates a novel mechanism of G protein activation that provides greater diversity of function of both the steroid hormone receptor and G proteins.
authors.affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9063, USA.
authors.forename: Premlata
authors.initials: P
authors.lastname: Kumar
authors.forename: Qian
authors.initials: Q
authors.lastname: Wu
authors.forename: Ken L
authors.initials: KL
authors.lastname: Chambliss
authors.forename: Ivan S
authors.initials: IS
authors.lastname: Yuhanna
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Mumby
authors.forename: Chieko
authors.initials: C
authors.lastname: Mineo
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Tall
authors.forename: Philip W
authors.initials: PW
authors.lastname: Shaul
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D019281:Dimerization; D042783:Endothelial Cells / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000378:metabolism*; D006801:Humans; D016296:Mutagenesis; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D047628:Estrogen Receptor alpha; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D011994:Recombinant Proteins; D004958:Estradiol; D019061:src-Family Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go