| First Author | Zippel N | Year | 2018 |
| Journal | Int J Mol Sci | Volume | 19 |
| Issue | 9 | PubMed ID | 30217073 |
| Mgi Jnum | J:346524 | Mgi Id | MGI:7616566 |
| Doi | 10.3390/ijms19092753 | Citation | Zippel N, et al. (2018) Endothelial AMP-Activated Kinase alpha1 Phosphorylates eNOS on Thr495 and Decreases Endothelial NO Formation. Int J Mol Sci 19(9) |
| abstractText | 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 AMPKalpha1 and alpha2 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 (AMPKalpha(-/-)) or endothelial-specific deletion (AMPKalpha(DeltaEC)) of the AMPKalpha subunits. In control and AMPKalpha1-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 AMPKalpha1 or alpha2 subunit in mice did not affect vascular reactivity. The endothelial-specific deletion of the AMPKalpha1 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 AMPKalpha1 in cultured human endothelial cells decreased Thr495 phosphorylation without affecting Ser1177 phosphorylation. The results of this study indicate that AMPKalpha1 targets the inhibitory phosphorylation Thr495 site in the calmodulin-binding domain of eNOS to attenuate basal NO production and phenylephrine-induced vasoconstriction. |
