Estradiol-Mediated Endothelial Nitric Oxide Synthase Association With Heat Shock Protein 90 Requires Adenosine Monophosphate-Dependent Protein Kinase

Abstract

Background— Estradiol activates endothelial nitric oxide synthase (eNOS) by mechanisms that involve estrogen receptor-α (ERα), protein kinase B/Akt, mitogen-activated protein kinases, and heat shock protein 90 (HSP90). Recently, AMP-activated protein kinase (AMPK), an enzyme that plays a crucial role in cellular adaptation to metabolic stress, has been implicated in physiological eNOS activation by the hormones adiponectin and insulin. We therefore investigated whether AMPK is activated by estradiol in endothelial cells and plays a role in estradiol-induced eNOS activation. Methods and Results— Porcine aortic endothelial cells exhibited time- and concentration-dependent AMPK activation as determined by phosphorylation of AMPK and its downstream target acetyl coenzyme A carboxylase in response to estradiol (1 nmol/L to 10 μmol/L, 1 to 30 minutes). AMPK activation by estradiol was independent of both AMP levels and ERα but required estradiol conversion to its catechol metabolites. Estradiol treatment increa...