Affiliation:
1. From the Division of Cardiovascular Medicine and Molecular Cardiobiology, Boyer Center for Molecular Medicine (M.P.H., D.S., K.S.R., M.C., J.R.B.) and Department of Pharmacology (D.F., M.M.-R., W.C.S.), Yale University School of Medicine, New Haven, Conn.
Abstract
Abstract
—17β-Estradiol (E
2
) is a rapid activator of endothelial nitric oxide synthase (eNOS). The product of this activation event, NO, is a fundamental determinant of cardiovascular homeostasis. We previously demonstrated that E
2
-stimulated endothelial NO release can occur without an increase in cytosolic Ca
2+
. Here we demonstrate for the first time, to our knowledge, that E
2
rapidly induces phosphorylation and activation of eNOS through the phosphatidylinositol 3 (PI3)-kinase–Akt pathway. E
2
treatment (10 ng/mL) of the human endothelial cell line, EA.hy926, resulted in increased NO production, which was abrogated by the PI3-kinase inhibitor, LY294002, and the estrogen receptor antagonist ICI 182,780. E
2
stimulated rapid Akt phosphorylation on serine 473. As has been shown for vascular endothelial growth factor, eNOS is an E
2
-activated Akt substrate, demonstrated by rapid eNOS phosphorylation on serine 1177, a critical residue for eNOS activation and enhanced sensitivity to resting cellular Ca
2+
levels. Adenoviral-mediated EA.hy926 transduction confirmed functional involvement of Akt, because a kinase-deficient, dominant-negative Akt abolished E
2
-stimulated NO release. The membrane-impermeant E
2
BSA conjugate, shown to bind endothelial cell membrane sites, also induced rapid Akt and consequent eNOS phosphorylation. Thus, engagement of membrane estrogen receptors results in rapid endothelial NO release through a PI3-kinase–Akt-dependent pathway. This explains, in part, the reduced requirement for cytosolic Ca
2+
fluxes and describes an important pathway relevant to cardiovascular pathophysiology.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine,Physiology
Cited by
487 articles.
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