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.
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.
Fulton
David
D
Department of Pharmacology and Molecular Cardiobiology Program, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536, USA.
Fontana
Jason
J
Sowa
Grzegorz
G
Gratton
Jean-Philippe
JP
Lin
Michelle
M
Li
Kai-Xun
KX
Michell
Belinda
B
Kemp
Bruce E
BE
Rodman
David
D
Sessa
William C
WC
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D016228:Endothelial Growth Factors / Q000378:metabolism; D006056:Golgi Apparatus / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D008222:Lymphokines / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000737:chemistry / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010766:Phosphorylation; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor; D012694:Serine / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D009569:Nitric Oxide; D012694:Serine; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor