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(Circulation. 2009;119:871-879.)
© 2009 American Heart Association, Inc.
Vascular Medicine |
From the Center for Vascular Biology Research and the Division of Vascular Surgery, Department of Surgery (C.G.d.S., C.F., E.K.), Department of Medicine (A.S.), and Transplantation Institute, Department of Surgery (B.W.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass. A. Specht is now at the Institute of Virology, University of Ulm, Ulm, Germany.
Correspondence to Elzbieta Kaczmarek, Beth Israel Deaconess Medical Center, Harvard Medical School, RN280A, 99 Brookline Ave, Boston, MA 02215. E-mail ekaczmar{at}bidmc.harvard.edu
Received January 9, 2008; accepted November 25, 2008.
Background— Decreased endothelial nitric oxide (NO) synthase (eNOS) activity and NO production are critical contributors to the endothelial dysfunction and vascular complications observed in many diseases, including diabetes mellitus. Extracellular nucleotides activate eNOS and increase NO generation; however, the mechanism of this observation is not fully clarified.
Methods and Results— To elucidate the signaling pathway(s) leading to nucleotide-mediated eNOS phosphorylation at Ser-1177, human umbilical vein endothelial cells were treated with several nucleotides, including ATP, UTP, and ADP, in the presence or absence of selective inhibitors. These experiments identified P2Y1, P2Y2, and possibly P2Y4 as the purinergic receptors involved in eNOS phosphorylation and demonstrated that this process was adenosine independent. Nucleotide-induced eNOS phosphorylation and activity were inhibited by BAPTA-AM (an intracellular free calcium chelator), rottlerin (a protein kinase C
inhibitor), and protein kinase C
siRNA. In contrast, blockade of AMP-activated protein kinase, calcium/calmodulin-dependent kinase II, calcium/calmodulin-dependent kinase kinase, serine/threonine protein kinase B, protein kinase A, extracellular signal-regulated kinase 1/2, and p38 mitogen-activated protein kinase did not affect nucleotide-mediated eNOS phosphorylation.
Conclusions— The present study indicates that extracellular nucleotide–mediated eNOS phosphorylation is calcium and protein kinase C
dependent. This newly identified signaling pathway opens new therapeutic avenues for the treatment of endothelial dysfunction.
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