Identification of nitric oxide as an endogenous activator of the AMP-activated protein kinase in vascular endothelial cells.
In endothelial cells, the AMP-activated protein kinase (AMPK) is stimulated by sheer stress or growth factors that stimulate release of nitric oxide (NO). We hypothesized that NO might act as an endogenous activator of AMPK in endothelial cells. Exposure of human umbilical vein endothelial cells (HUVECs) to NO donors caused an increase in phosphorylation of both Thr-172 of AMPK and Ser-1177 of endothelial nitric oxide synthase, a downstream enzyme of AMPK. NO-induced activation of AMPK was not affected by inhibition of LKB1, an AMPK kinase. In contrast, inhibition of calcium calmodulin-dependent protein kinase kinase abolished the effect of NO in HUVECs. NO-induced AMPK activation in HeLa S3 cells was abolished by either 1H-(1,2,4)-oxadiazole[4,3-a]quinoxalon-1-one, a potent inhibitor for guanylyl cyclase, or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis (acetoxymethyl ester) (BAPTA-AM), an intracellular Ca(2+) chelator, indicating that NO-induced AMPK activation is guanylyl cyclase-mediated and calcium-dependent. Exposure of HUVECs or isolated mice aortas to either calcium ionophore A23187 or bradykinin significantly increased AMPK Thr-172 phosphorylation, which was abolished by N-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthase. Finally, A23187- or bradykinin-enhanced AMPK activation was significantly greater in aortas from wild type mice than those in the aortas of endothelial nitric oxide synthase knock-out mice. Taken together, we conclude that NO might act as an endogenous AMPK activator.
Zhang
Junhua
J
Division of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
Xie
Zhonglin
Z
Division of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
Dong
Yunzhou
Y
Division of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
Wang
Shuangxi
S
Division of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
Liu
Chao
C
Division of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
Zou
Ming-Hui
MH
Division of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104. Electronic address: ming-hui-zou@ouhsc.edu.
D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; D000818:Animals; D001011:Aorta / Q000201:enzymology*; D042783:Endothelial Cells / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D014471:Umbilical Veins / Q000201:enzymology*
D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; C109790:STK11 protein, human; C491654:Stk11 protein, mouse; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases