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Calcineurin-mediated dephosphorylation of eNOS at serine 116 affects eNOS enzymatic activity indirectly by

Ling Ruan1, Christina M Torres, Ryan J Buffett

  • 1Vascular Biology Center, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta, GA 30912, USA.

Vascular Pharmacology
|June 4, 2013
PubMed

Insights

Calcineurin dephosphorylates endothelial nitric oxide synthase (eNOS) at serine 116, indirectly activating it. This process facilitates c-Src binding and tyrosine 83 phosphorylation, enhancing eNOS activity.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Background:

  • Endothelial nitric oxide synthase (eNOS) activity is suppressed by phosphorylation at serine 116 (S116) under basal conditions.
  • Vascular endothelial growth factor (VEGF) treatment causes rapid S116 dephosphorylation, inhibited by cyclosporin A (CsA).

Purpose of the Study:

  • To investigate the role of calcineurin in eNOS regulation.
  • To elucidate the mechanism by which S116 dephosphorylation influences eNOS activity.

Main Methods:

  • Studied eNOS phosphorylation and dephosphorylation in response to various agonists and thapsigargin.
  • Utilized purified eNOS enzyme to assess the effect of S116 phosphorylation/mimicking on enzymatic activity.
  • Examined the interaction between eNOS and c-Src under calcineurin inhibition.

Main Results:

  • Agonist-induced eNOS activation involves CsA-inhibitable S116 dephosphorylation.
  • Phosphorylation or phospho-mimicking at S116 did not directly affect purified eNOS activity.
  • Mimicking S116 phosphorylation impaired eNOS-c-Src interaction, crucial for tyrosine 83 (Y83) phosphorylation.
  • Calcineurin inhibition blocked agonist-stimulated eNOS-Src complex formation and Y83 phosphorylation.

Conclusions:

  • Calcineurin-mediated eNOS S116 dephosphorylation indirectly enhances eNOS activity.
  • This indirect activation occurs by promoting c-Src binding and subsequent Y83 phosphorylation.
  • Suggests a regulatory mechanism involving calcineurin, S116, c-Src, and Y83 in eNOS function.
Keywords:
ANGBAECsBKCAIPCalcineurinCyclosporin ADephosphorylationERKEndothelial nitric oxide synthase (eNOS)PP1PP2APP2BPP2CPhosphorylationPinTGVEGFangiopoietinbovine aortic endothelial cellsbradykinincalcineurin autoinhibitory peptideeNOSendothelial nitric oxide synthaseextracellular signal regulated kinaseprotein interacting with never in mitosis Aprotein phosphatase-1protein phosphatase-2Aprotein phosphatase-2Bprotein phosphatase-2Cthapsigarginvascular endothelial growth factor

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