Adiponectin-induced endothelial nitric oxide synthase activation and nitric oxide production are mediated by APPL1 in endothelial cells

Diabetes. 2007 May;56(5):1387-94. doi: 10.2337/db06-1580. Epub 2007 Feb 7.


Adiponectin protects the vascular system partly through stimulation of endothelial nitric oxide (NO) production and endothelium-dependent vasodilation. The current study investigated the role of two recently identified adiponectin receptors, AdipoR1 and -R2, and their downstream effectors in mediating the endothelium actions of adiponectin. In human umbilical vein endothelial cells, adiponectin-induced phosphorylation of endothelial NO synthase (eNOS) at Ser(1177) and NO production were abrogated when expression of AdipoR1 and -R2 were simultaneously suppressed. Proteomic analysis demonstrated that the cytoplasmic tails of both AdipoR1 and -R2 interacted with APPL1, an adaptor protein that contains a PH (pleckstrin homology) domain, a PTB (phosphotyrosine-binding) domain, and a Leucine zipper motif. Suppression of APPL1 expression by RNA interference significantly attenuated adiponectin-induced phosphorylation of AMP-activated protein kinase (AMPK) at Thr(172) and eNOS at Ser(1177), and the complex formation between eNOS and heat shock protein 90, resulting in a marked reduction of NO production. Adenovirus-mediated overexpression of a constitutively active version of AMPK reversed these changes. In db/db diabetic mice, both APPL1 expression and adiponectin-induced vasodilation were significantly decreased compared with their lean littermates. Taken together, these results suggest that APPL1 acts as a common downstream effector of AdipoR1 and -R2, mediating adiponectin-evoked endothelial NO production and endothelium-dependent vasodilation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases
  • Adaptor Proteins, Signal Transducing
  • Adiponectin / pharmacology*
  • Apoptosis / drug effects
  • Apoptosis / physiology
  • Carrier Proteins / genetics*
  • Cells, Cultured
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / enzymology
  • Endothelium, Vascular / physiology*
  • Enzyme Activation / drug effects
  • Genetic Vectors
  • Humans
  • Isometric Contraction / drug effects
  • Isometric Contraction / physiology
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism
  • Nitric Oxide / biosynthesis*
  • Nitric Oxide Synthase Type III / drug effects
  • Nitric Oxide Synthase Type III / metabolism*
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • Receptors, Adiponectin
  • Receptors, Cell Surface / genetics
  • Recombinant Fusion Proteins / metabolism
  • Umbilical Veins
  • Vasodilation / drug effects
  • Vasodilation / physiology


  • ADIPOR1 protein, human
  • ADIPOR2 protein, human
  • APPL1 protein, human
  • Adaptor Proteins, Signal Transducing
  • Adiponectin
  • Carrier Proteins
  • Multienzyme Complexes
  • Receptors, Adiponectin
  • Receptors, Cell Surface
  • Recombinant Fusion Proteins
  • Nitric Oxide
  • Nitric Oxide Synthase Type III
  • Protein-Serine-Threonine Kinases
  • AMP-Activated Protein Kinases