scholarly journals The N-terminal portion of autoinhibitory element modulates human endothelial nitric-oxide synthase activity through coordinated controls of phosphorylation at Thr495 and Ser1177

2014 ◽  
Vol 34 (4) ◽  
Author(s):  
Pei-Rung Wu ◽  
Bo-Rui Chen ◽  
Chi-Chun Hsieh ◽  
Wei-Chung Lin ◽  
Kenneth K. Wu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Regulatory Function ◽  
Terminal Portion ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide ◽  
First Time ◽  
Nitric Oxide Synthase Activity

Our findings demonstrate for the first time that AIE insert exerts its regulatory function by coordinate phosphorylation on eNOS Ser1177 and Thr495, highlighting the importance of AIE in regulating agonist-induced eNOS activation.

Increasing dihydrobiopterin causes dysfunction of endothelial nitric oxide synthase in rats in vivo

2011 ◽  
Vol 301 (3) ◽  
pp. H721-H729 ◽  
Author(s):  
Katsuhiko Noguchi ◽  
Naobumi Hamadate ◽  
Toshihiro Matsuzaki ◽  
Mayuko Sakanashi ◽  
Junko Nakasone ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Control Treatment ◽  
Enos Uncoupling ◽  
Nos Inhibitor ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide ◽  
First Time

An elevation of oxidized forms of tetrahydrobiopterin (BH4), especially dihydrobiopterin (BH2), has been reported in the setting of oxidative stress, such as arteriosclerotic/atherosclerotic disorders, where endothelial nitric oxide synthase (eNOS) is dysfunctional, but the role of BH2 in the regulation of eNOS activity in vivo remains to be evaluated. This study was designed to clarify whether increasing BH2 concentration causes endothelial dysfunction in rats. To increase vascular BH2 levels, the BH2 precursor sepiapterin (SEP) was intravenously given after the administration of the specific dihydrofolate reductase inhibitor methotrexate (MTX) to block intracellular conversion of BH2 to BH4. MTX/SEP treatment did not significantly affect aortic BH4 levels compared with control treatment. However, MTX/SEP treatment markedly augmented aortic BH2 levels (291.1 ± 29.2 vs. 33.4 ± 6.4 pmol/g, P < 0.01) in association with moderate hypertension. Treatment with MTX alone did not significantly alter blood pressure or BH4 levels but decreased the BH4-to-BH2 ratio. Treatment with MTX/SEP, but not with MTX alone, impaired ACh-induced vasodilator and depressor responses compared with the control treatment (both P < 0.05) and also aggravated ACh-induced endothelium-dependent relaxations ( P < 0.05) of isolated aortas without affecting sodium nitroprusside-induced endothelium-independent relaxations. Importantly, MTX/SEP treatment significantly enhanced aortic superoxide production, which was diminished by NOS inhibitor treatment, and the impaired ACh-induced relaxations were reversed with SOD ( P < 0.05), suggesting the involvement of eNOS uncoupling. These results indicate, for the first time, that increasing BH2 causes eNOS dysfunction in vivo even in the absence of BH4 deficiency, demonstrating a novel insight into the regulation of endothelial function.

scholarly journals eNOS activation and NO function: Structural motifs responsible for the posttranslational control of endothelial nitric oxide synthase activity

2011 ◽  
Vol 210 (3) ◽  
pp. 271-284 ◽  
Author(s):  
Ruslan Rafikov ◽  
Fabio V Fonseca ◽  
Sanjiv Kumar ◽  
Daniel Pardo ◽  
Charles Darragh ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Posttranslational Modifications ◽  
Endothelial Nitric Oxide Synthase ◽  
Regulatory Region ◽  
Enos Uncoupling ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide ◽  
Nitric Oxide Synthase Activity

Rather than being a constitutive enzyme as was first suggested, endothelial nitric oxide synthase (eNOS) is dynamically regulated at the transcriptional, posttranscriptional, and posttranslational levels. This review will focus on how changes in eNOS function are conferred by various posttranslational modifications. The latest knowledge regarding eNOS targeting to the plasma membrane will be discussed as the role of protein phosphorylation as a modulator of catalytic activity. Furthermore, new data are presented that provide novel insights into how disruption of the eNOS dimer prevents eNOS uncoupling and the production of superoxide under conditions of elevated oxidative stress and identifies a novel regulatory region we have termed the ‘flexible arm’.

scholarly journals Inhibition of MEK/ERK1/2 signalling alters endothelial nitric oxide synthase activity in an agonist-dependent manner

2006 ◽  
Vol 398 (2) ◽  
pp. 279-288 ◽  
Author(s):  
Jacqueline M. Cale ◽  
Ian M. Bird
Keyword(s):  
Nitric Oxide ◽  
Protein Kinase ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Intracellular Trafficking ◽  
Enos Activity ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide ◽  
Nitric Oxide Synthase Activity

eNOS (endothelial nitric oxide synthase) activity is post-translationally regulated in a complex fashion by acylation, protein–protein interactions, intracellular trafficking and phosphorylation, among others. Signalling pathways that regulate eNOS activity include phosphoinositide 3-kinase/Akt, cyclic nucleotide-dependent kinases [PKA (protein kinase A) and PKG], PKC, as well as ERKs (extracellular-signal-regulated kinases). The role of ERKs in eNOS activation remains controversial. In the present study, we have examined the role of ERK1/2 in eNOS activation in HUVEC-CS [transformed HUVEC (human umbilical-vein endothelial cells)] as well as a widely used model for eNOS study, transiently transfected COS-7 cells. U0126 pretreatment of HUVEC-CS potentiated ATP-stimulated eNOS activity, independent of changes in intracellular Ca2+ concentration ([Ca2+]i). In COS-7 cells transiently expressing ovine eNOS, U0126 potentiated A23187-stimulated eNOS activity, but inhibited ATP-stimulated activity. Compensatory changes in phosphorylation of five key eNOS residues did not account for changes in A23187-stimulated activity. However, in the case of ATP, altered phosphorylation and changes in [Ca2+]i may partially contribute to U0126 inhibition of activity. Finally, seven eNOS alanine mutants of putative ERK1/2 targets were generated and the effects of U0126 pretreatment on eNOS activity were gauged with A23187 and ATP treatment. T97A-eNOS was the only construct significantly different from wild-type after U0126 pretreatment and ATP stimulation of eNOS activation. In the present study, eNOS activity was either potentiated or inhibited in COS-7 cells, suggesting agonist dependence for MEK/ERK1/2 signalling [where MEK is MAPK (mitogen-activated protein kinase)/ERK kinase] to eNOS and a complex mechanism including [Ca2+]i, phosphorylation and, possibly, intracellular trafficking.

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