Journal of Biological Chemistry
Volume 277, Issue 6, 8 February 2002, Pages 4277-4284
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MECHANISMS OF SIGNAL TRANSDUCTION
Localization of Endothelial Nitric-oxide Synthase Phosphorylated on Serine 1179 and Nitric Oxide in Golgi and Plasma Membrane Defines the Existence of Two Pools of Active Enzyme*

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The subcellular localization of endothelial nitric-oxide synthase (eNOS) is critical for optimal coupling of extracellular stimulation to nitric oxide production. Because eNOS is activated by Akt-dependent phosphorylation to produce nitric oxide (NO), we determined the subcellular distribution of eNOS phosphorylated on serine 1179 using a variety of methodologies. Based on sucrose gradient fractionation, phosphorylated-eNOS (P-eNOS) was found in both caveolin-1-enriched membranes and intracellular domains. Co-transfection of eNOS with Akt and stimulation of endothelial cells with vascular endothelial growth factor (VEGF) increased the ratio of P-eNOS to total eNOS but did not change the relative intracellular distribution between these domains. The proper localization of eNOS to intracellular membranes was required for agonist-dependent phosphorylation on serine 1179, since VEGF did not increase eNOS phosphorylation in cells transfected with a non-acylated, mistargeted form of eNOS. Confocal imaging of P-eNOS and total eNOS pools demonstrated co-localization in the Golgi region and plasmalemma of transfected cells and native endothelial cells. Finally, VEGF stimulated a large increase in NO localized in both the perinuclear region and the plasma membrane of endothelial cells. Thus, activated, phosphorylated eNOS resides in two cellular compartments and both pools are VEGF-regulated to produce NO.

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Published, JBC Papers in Press, November 29, 2001, DOI 10.1074/jbc.M106302200

*

This work was supported by National Institutes of Health Grants RO1 HL57665, HL61371, and HL64793 (to W. C. S.), T32HL10183 (to D. F.), and HL48038 (to D. R.) and a grant-in-aid from the American Heart Association (National Grant to W. C. S.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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Recipient of a fellowship from the Canadian Institutes of Health Research.