title: Coordinated control of endothelial nitric-oxide synthase phosphorylation by protein kinase C and the cAMP-dependent protein kinase.
abstract: Endothelial nitric-oxide synthase (eNOS) is an important regulatory enzyme in the cardiovascular system catalyzing the production of NO from arginine. Multiple protein kinases including Akt/PKB, cAMP-dependent protein kinase (PKA), and the AMP-activated protein kinase (AMPK) activate eNOS by phosphorylating Ser-1177 in response to various stimuli. During VEGF signaling in endothelial cells, there is a transient increase in Ser-1177 phosphorylation coupled with a decrease in Thr-495 phosphorylation that reverses over 10 min. PKC signaling in endothelial cells inhibits eNOS activity by phosphorylating Thr-495 and dephosphorylating Ser-1177 whereas PKA signaling acts in reverse by increasing phosphorylation of Ser-1177 and dephosphorylation of Thr-495 to activate eNOS. Both phosphatases PP1 and PP2A are associated with eNOS. PP1 is responsible for dephosphorylation of Thr-495 based on its specificity for this site in both eNOS and the corresponding synthetic phosphopeptide whereas PP2A is responsible for dephosphorylation of Ser-1177. Treatment of endothelial cells with calyculin selectively blocks PKA-mediated dephosphorylation of Thr-495 whereas okadaic acid selectively blocks PKC-mediated dephosphorylation of Ser-1177. These results show that regulation of eNOS activity involves coordinated signaling through Ser-1177 and Thr-495 by multiple protein kinases and phosphatases.
authors: St. Vincent's Institute of Medical Research, St. Vincent's Hospital, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia.
authors: B J
authors: BJ
authors: Michell
authors: Chen Zp
authors: T
authors: T
authors: Tiganis
authors: D
authors: D
authors: Stapleton
authors: F
authors: F
authors: Katsis
authors: D A
authors: DA
authors: Power
authors: A T
authors: AT
authors: Sim
authors: B E
authors: BE
authors: Kemp
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C