Plasma Membrane Estrogen Receptors Are Coupled to Endothelial Nitric-oxide Synthase through Gαi

Myra H. Wyckoff, Ken L. Chambliss, Chieko Mineo, Ivan S. Yuhanna, Michael E. Mendelsohn, Susanne M. Mumby, Philip W. Shaul

Research output: Contribution to journalArticlepeer-review

250 Scopus citations

Abstract

Estrogen causes rapid endothelial nitric oxide (NO) production because of the activation of plasma membrane-associated estrogen receptors (ER) coupled to endothelial NO synthase (eNOS). In the present study, we determined the role of G proteins in eNOS activation by estrogen. Estradiol-17β (E2, 10-8 M) and acetylcholine (10-5 M) caused comparable increases in NOS activity (15 min) in intact endothelial cells that were fully blocked by pertussis toxin (Ptox). In addition, exogenous guanosine 5′-O-(2-thiodiphosphate) inhibited E2-mediated eNOS stimulation in isolated endothelial plasma membranes, and Ptox prevented enzyme activation by E2 in COS-7 cells expressing ERα and eNOS. Coimmunoprecipitation studies of plasma membranes from COS-7 cells transfected with ERα and specific Gα proteins demonstrated E 2-stimulated interaction between ERα and Gαi but not between ERα and either Gαq or Gα s; the observed ERα-Gαi interaction was blocked by the ER antagonist ICI 182,780 and by Ptox. E2-stimulated ERα-Gαi interaction was also demonstrable in endothelial cell plasma membranes. Cotransfection of Gαi into COS-7 cells expressing ERα and eNOS yielded a 3-fold increase in E 2-mediated eNOS stimulation, whereas cotransfection with a protein regulator of G protein signaling, RGS4, inhibited the E2 response. These findings indicate that eNOS stimulation by E2 requires plasma membrane ERα coupling to Gαi and that activated Gαi mediates the requisite downstream signaling events. Thus, novel G protein coupling enables a subpopulation of ERα to initiate signal transduction at the cell surface. Similar mechanisms may underly the nongenomic actions of other steroid hormones.

Original languageEnglish (US)
Pages (from-to)27071-27076
Number of pages6
JournalJournal of Biological Chemistry
Volume276
Issue number29
DOIs
StatePublished - Jul 20 2001

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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