Insulin-dependent activation of endothelial nitric oxide synthase is impaired by O-linked glycosylation modification of signaling proteins in human coronary endothelial cells

Circulation. 2002 Jul 23;106(4):466-72. doi: 10.1161/01.cir.0000023043.02648.51.

Abstract

Background: Hyperglycemia impairs functional properties of cytosolic and nuclear proteins via O-linked glycosylation modification (O-GlcNAcylation). We studied the effects of O-GlcNAcylation on insulin signaling in human coronary artery endothelial cells.

Methods and results: O-GlcNAcylation impaired the metabolic branch of insulin signaling, ie, insulin receptor (IR) activation of the IR substrate (IRS)/phosphatidylinositol 3-kinase (PI3-K)/Akt, whereas it enhanced the mitogenic branch, ie, ERK-1/2 and p38 (mitogen-activated protein kinase). Both in vivo and in vitro phosphorylation of endothelial nitric oxide synthase (eNOS) by Akt were reduced by hyperglycemia and hexosamine activation. Insulin-induced eNOS activity in vivo was reduced by hyperglycemia and hexosamine activation, which was coupled to increased activation and expression of matrix metalloproteinase-2 and -9; these phenomena were reversed by inhibition of the hexosamine pathway. Finally, carotid plaques from type 2 diabetic patients showed increased endothelial O-GlcNAcylation with respect to nondiabetics.

Conclusions: Our data show that hyperglycemia, through the hexosamine pathway, impairs activation of the IR/IRS/PI3-K/Akt pathway, resulting in deregulation of eNOS activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arteriosclerosis / complications
  • Arteriosclerosis / metabolism
  • Arteriosclerosis / pathology
  • Cells, Cultured
  • Coronary Vessels / cytology
  • Coronary Vessels / enzymology*
  • Coronary Vessels / metabolism
  • Diabetes Complications
  • Dose-Response Relationship, Drug
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / enzymology*
  • Endothelium, Vascular / metabolism
  • Enzyme Activation
  • Glucosamine / pharmacology
  • Glucose / pharmacology
  • Glycosylation
  • Humans
  • Insulin / pharmacology*
  • Insulin Antagonists / pharmacology
  • Matrix Metalloproteinases / metabolism
  • Nitric Oxide Synthase / metabolism*
  • Nitric Oxide Synthase Type III
  • Phosphorylation / drug effects
  • Proteins / metabolism
  • Signal Transduction* / drug effects
  • Tissue Inhibitor of Metalloproteinase-3 / metabolism

Substances

  • Insulin
  • Insulin Antagonists
  • Proteins
  • Tissue Inhibitor of Metalloproteinase-3
  • NOS3 protein, human
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type III
  • Matrix Metalloproteinases
  • Glucose
  • Glucosamine