Caveolin 1 and G-Protein-Coupled Receptor Kinase-2 Coregulate Endothelial Nitric Oxide Synthase Activity in Sinusoidal Endothelial Cells

Am J Pathol. 2017 Apr;187(4):896-907. doi: 10.1016/j.ajpath.2016.11.017. Epub 2017 Feb 3.


Liver injury leads to a vasculopathy in which post-translational modifications of endothelial nitric oxide synthase (eNOS) lead to impaired nitric oxide synthesis. We hypothesized that caveolin 1 (CAV1), a well-known eNOS interactor, regulates eNOS activity in sinusoidal endothelial cells (SECs) via its interaction with G-protein-coupled receptor kinase-2 (GRK2) that also post-translationally modifies eNOS. Liver injury with portal hypertension was established using bile duct ligation in rats. CAV1 function was modified using a CAV1 scaffolding domain construct and cDNAs encoding wild-type CAV1, and CAV1 phosphorylation was increased in injured SECs, resulting in increased GRK2-CAV1 interaction and decreased eNOS activity. In injured SECs, endothelin-1 blocked CAV1 phosphorylation induced by CAV1 scaffolding domain, indicating that CAV1 interaction with GRK2 is inversely regulated by endothelin-1 and CAV1 scaffolding domain after liver injury. In addition, after transduction with DNA encoding wild-type CAV1 into SECs isolated from Cav1-deficient mice, GRK2 association with CAV1 was evident, whereas transduction with a dominant negative CAV1 mutated at tyrosine 14 reduced the interaction. Finally, isoproterenol-induced GRK2 phosphorylation enhanced CAV1-GRK2 interaction and reduced eNOS activity. Our data suggest a novel mechanism and model in which CAV1 phosphorylation facilitates CAV1 scaffolding and GRK2-CAV1 interaction, thus clustering eNOS within a complex that inhibits eNOS activity. This process takes place in injured, but not in normal, SECs.

MeSH terms

  • Animals
  • Caveolin 1 / chemistry
  • Caveolin 1 / metabolism*
  • Endothelial Cells / drug effects
  • Endothelial Cells / metabolism*
  • Endothelial Cells / pathology
  • Endothelin-1 / metabolism
  • G-Protein-Coupled Receptor Kinases / metabolism*
  • Humans
  • Isoproterenol / pharmacology
  • Liver / injuries
  • Liver / pathology*
  • Male
  • Mice, Knockout
  • Models, Biological
  • Nitric Oxide Synthase Type III / metabolism*
  • Phosphorylation / drug effects
  • Phosphotyrosine / metabolism
  • Protein Binding / drug effects
  • Protein Domains
  • Rats, Sprague-Dawley
  • Receptor, Endothelin B / metabolism


  • Caveolin 1
  • Endothelin-1
  • Receptor, Endothelin B
  • Phosphotyrosine
  • Nitric Oxide Synthase Type III
  • G-Protein-Coupled Receptor Kinases
  • Isoproterenol