Endothelial AMP-activated kinase α1 phosphorylates eNOS on Thr495 and decreases endothelial NO formation

  • AMP-activated protein kinase (AMPK) is frequently reported to phosphorylate Ser1177 of the endothelial nitric-oxide synthase (eNOS), and therefore, is linked with a relaxing effect. However, previous studies failed to consistently demonstrate a major role for AMPK on eNOS-dependent relaxation. As AMPK also phosphorylates eNOS on the inhibitory Thr495 site, this study aimed to determine the role of AMPKα1 and α2 subunits in the regulation of NO-mediated vascular relaxation. Vascular reactivity to phenylephrine and acetylcholine was assessed in aortic and carotid artery segments from mice with global (AMPKα−/−) or endothelial-specific deletion (AMPKαΔEC) of the AMPKα subunits. In control and AMPKα1-depleted human umbilical vein endothelial cells, eNOS phosphorylation on Ser1177 and Thr495 was assessed after AMPK activation with thiopental or ionomycin. Global deletion of the AMPKα1 or α2 subunit in mice did not affect vascular reactivity. The endothelial-specific deletion of the AMPKα1 subunit attenuated phenylephrine-mediated contraction in an eNOS- and endothelium-dependent manner. In in vitro studies, activation of AMPK did not alter the phosphorylation of eNOS on Ser1177, but increased its phosphorylation on Thr495. Depletion of AMPKα1 in cultured human endothelial cells decreased Thr495 phosphorylation without affecting Ser1177 phosphorylation. The results of this study indicate that AMPKα1 targets the inhibitory phosphorylation Thr495 site in the calmodulin-binding domain of eNOS to attenuate basal NO production and phenylephrine-induced vasoconstriction.

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Author:Nina Zippel, Annemarieke E. Loot, Heike Stingl, Voahanginirina Randriamboavonjy, Ingrid FlemingORCiD, Beate Fißlthaler
Pubmed Id:https://pubmed.ncbi.nlm.nih.gov/30217073
Parent Title (English):International journal of molecular sciences
Publisher:Molecular Diversity Preservation International
Place of publication:Basel
Document Type:Article
Year of Completion:2018
Date of first Publication:2018/09/13
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2018/11/01
Tag:endothelial cells; endothelial nitric-oxide synthase; ionomycin; phenylephrine; vasoconstriction; vasodilation
Issue:9, Art. 2753
Page Number:15
First Page:1
Last Page:15
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
Institutes:Medizin / Medizin
Wissenschaftliche Zentren und koordinierte Programme / Sonderforschungsbereiche / Forschungskollegs
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Licence (German):License LogoCreative Commons - Namensnennung 4.0