c-Jun N-terminal kinase 2 phosphorylates endothelial nitric oxide synthase at serine 116 and regulates nitric oxide production
ABSTRACT The c-Jun N-terminal kinases (JNKs) belonging to the mitogen-activated protein kinase (MAPK) superfamily play important roles in foam-cell formation, hypercholesterolemia-mediated endothelial dysfunction, and the development of obesity. Although decreased nitric oxide (NO) production via decreased phosphorylation of endothelial NO synthase at serine 1179 (eNOS-Ser(1179)) was reported to be partly involved in JNK2-derived endothelial dysfunction, JNK2 seems likely to be indirectly involved in this signaling pathway. Here, using bovine aortic endothelial cells, we examined whether JNK2 directly phosphorylated eNOS-Ser(116), a putative substrate site for the MAPK superfamily, and this phosphorylation resulted in decreased NO release. JNK inhibitor SP60012 increased NO release in a time- and dose-dependent manner, which was accompanied by increased eNOS-Ser(116) phosphorylation. Purified JNK2 directly phosphorylated eNOS-Ser(116)in vitro. Ectopic expression of dominant negative JNK2 repressed eNOS-Ser(116) phosphorylation and increased NO production. Coimmunoprecipitation and confocal microscopy studies revealed a colocalization of eNOS and JNK2. However, all these observed effects were not manifested when JNK1 probes were used. Overall, this study indicates that JNK2 is a physiological kinase responsible for eNOS-Ser(116) phosphorylation and regulates NO production.
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ABSTRACT: We aimed to investigate specific roles of mitogen activated protein kinases (MAPK) in the deterioration of endothelial function during the progression of diabetes and the potential therapeutic effects of MAPK inhibitors and agonists in the amelioration of endothelial function. Protein expression and phosphorylation of p38, c-Jun NH(2)-terminal kinase (JNK), and extracellular signal-regulated kinase (Erk) were assessed in mesenteric arteries of 3-month (3M) and 9-month (9M) male diabetic and control mice. The expression of p38, JNK, and Erk was comparable in all groups of mice, but the phosphorylation of p38 and JNK was increased in 3M and further increased in 9M diabetic mice, whereas the phosphorylation of Erk was substantially reduced in 9M diabetic mice. NADPH oxidase-dependent superoxide production was significantly increased in vessels of two ages of diabetic mice. Inhibition of either p38 with SB203580 or JNK with SP600125 reduced superoxide production and improved shear stress-induced dilation (SSID) in 3M, but not in 9M, diabetic mice. Treating the vessels of 9M diabetic mice with resveratrol increased Erk phosphorylation and shear stress-induced endothelial nitric oxide synthase (eNOS) phosphorylation and activity, but resveratrol alone did not improve SSID. Administration of resveratrol and SB203580 or resveratrol and SP600125 together significantly improved SSID in vessels of 9M diabetic mice. The improved response was prevented by U0126, an Erk inhibitor. Thus, p38/JNK-dependent increase in oxidative stress diminished nitric oxide-mediated dilation in vessels of 3M diabetic mice. Oxidative stress and impaired Erk-dependent activation of eNOS exacerbates endothelial dysfunction in the advanced stage of diabetes.Diabetes 08/2012; 61(12). DOI:10.2337/db12-0559 · 8.47 Impact Factor
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ABSTRACT: High levels of NO generated in the vasculature under inflammatory conditions are usually attributed to inducible nitric oxide synthase (iNOS), but the role of the constitutively expressed endothelial NOS (eNOS) is unclear. In normal human lung microvascular endothelial cells (HLMVEC), bradykinin (BK) activates kinin B2 receptor (B2R) signaling that results in Ca2+-dependent activation of eNOS and transient NO. In inflamed HLMVEC (pretreated with interleukin-1β and interferon-γ, we found enhanced binding of eNOS to calcium-calmodulin at basal Ca2+ levels, thereby increasing its basal activity that was dependent on extracellular L-Arg. Furthermore, B2R stimulation generated prolonged high output eNOS-derived NO that is independent of increased intracellular Ca2+ and is mediated by a novel Gαi, MEK1/2 and JNK1/2-dependent pathway. This high output NO stimulated with BK was blocked with B2R antagonist, eNOS siRNA or eNOS inhibitor but not iNOS inhibitor. Moreover, B2R-mediated NO production and JNK phosphorylation were inhibited with MEK1/2 and JNK inhibitors or MEK1/2 and JNK1/2 siRNA but not with ERK1/2 inhibitor. BK induced Ca2+-dependent eNOS phosphorylation at Ser1177, Thr495 and Ser114 in cytokine-treated HLMVEC but these modifications were not dependent on JNK1/2 activation and were not responsible for prolonged NO output. Cytokine treatment did not alter the expression of B2R, Gαq/11, Gαi1,2, JNK or eNOS. B2R activation in control endothelial cells enhanced migration, but in cytokine-treated HLMVEC it reduced migration. Both responses were NO-dependent. Understanding how JNK regulates prolonged eNOS-derived NO may provide new therapeutic targets for the treatment of disorders involving vascular inflammation.Journal of Biological Chemistry 12/2012; DOI:10.1074/jbc.M112.436022 · 4.60 Impact Factor
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ABSTRACT: Estrogens promote beneficial effects in the cardiovascular system mainly through the estrogen receptor (ER)α and ERβ, which act as ligand-gated transcription factors. Recently, the G protein-coupled estrogen receptor (GPER) has been implicated in the estrogenic signaling in diverse tissues, including the cardiovascular system. In this study, we demonstrate that left ventricles of male Spontaneously Hypertensive Rats (SHR) express higher levels of GPER compared to normotensive Wistar Kyoto (WKY) rats. In addition, we show that the selective GPER agonist G-1 induces negative inotropic and lusitropic effects to a higher extent in isolated and Langendorff perfused hearts of male SHR compared to WKY rats. These cardiotropic effects elicited by G-1 involved the GPER/eNOS transduction signaling, as determined by using the GPER antagonist G15 and the eNOS inhibitor L-NIO. Similarly, the G-1 induced activation of ERK1/2, AKT, GSK3β, c-Jun and eNOS was abrogated by G15, while L-NIO prevented only the eNOS phosphorylation. In hypoxic Langendorff perfused WKY rat heart preparations, we also found an increased expression of GPER along with that of the hypoxic mediator HIF-1α and the fibrotic marker CTGF. Interestingly, G15 and L-NIO prevented the ability of G-1 to down-regulate the expression of both HIF-1α and CTGF, which were found expressed to a higher extent in SHR compared to WKY rat hearts. Collectively, the present study provides novel data into the potential role played by GPER in hypertensive disease on the basis of its involvement in myocardial inotropism and lusitropism as well as the expression of the apoptotic HIF-1α and fibrotic CTGF factors. Hence, GPER may be considered as a useful target in the treatment of some cardiac dysfunctions associated with stressful conditions like the essential hypertension.PLoS ONE 08/2013; 8(8):e69322. DOI:10.1371/journal.pone.0069322 · 3.53 Impact Factor