title: 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-alpha (ERalpha), 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.
  
  
  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 micromol/L, 1 to 30 minutes). AMPK activation by estradiol was independent of both AMP levels and ERalpha but required estradiol conversion to its catechol metabolites. Estradiol treatment increased eNOS catalytic activity, an effect that was largely reversed when endothelial cells were infected with an AMPK dominant-negative adenovirus. However, inhibition of AMPK did not alter estradiol-induced eNOS phosphorylation at serine 1177 or threonine 495 but decreased eNOS interaction with HSP90. Consistent with this observation, blood vessels from alpha1-AMPK-null mice exhibited defective eNOS-mediated NO production in response to estradiol.
  
  
  CONCLUSIONS
  Taken together, these data indicate that AMPK activity is essential for estradiol-induced eNOS activation via the promotion of eNOS interaction with HSP90. These data point to a novel role for AMPK in modulating endothelial cell NO bioactivity and HSP90 function.
authors.affiliation: Evans Memorial Department of Medicine, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Mass 02118, USA.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Schulz
authors.forename: Elad
authors.initials: E
authors.lastname: Anter
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Zou
authors.forename: John F
authors.initials: JF
authors.lastname: Keaney
mesh_terms: D000263:Adenylate Kinase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D001011:Aorta / Q000166:cytology; D002396:Catechols; D004730:Endothelium, Vascular / Q000166:cytology; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology*; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000096:biosynthesis; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding / Q000187:drug effects; D013552:Swine; D014161:Transduction, Genetic
chemical_list: D002396:Catechols; D018841:HSP90 Heat-Shock Proteins; D009569:Nitric Oxide; D004958:Estradiol; D052250:Nitric Oxide Synthase Type III; D000263:Adenylate Kinase