Effects of retinol binding protein-4 on vascular endothelial cells

Biochem Biophys Res Commun. 2011 Apr 29;408(1):58-64. doi: 10.1016/j.bbrc.2011.03.116. Epub 2011 Mar 30.

Abstract

The study was designed to investigate the effect of retinol binding protein (RBP)-4 on the phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways, which mediate the effects of insulin in vascular endothelial cells. The effects of RBP4 on nitric oxide (NO) and insulin-stimulated endothelin-1 (ET-1) secretion and on phosphorylation (p) of Akt, endothelial NO synthetase (eNOS), and extracellular signal-regulated kinase (ERK)1/2 were investigated in bovine vascular aortic endothelial cells (BAECs). RBP4 showed an acute vasodilatatory effect on aortic rings of rats within a few minutes. In BAECs, RBP4-treatment for 5min significantly increased NO production, but inhibited insulin-stimulated ET-1 secretion. RBP4-induced NO production was not inhibited by tetraacetoxymethylester (BAPTA-AM), an intracellular calcium chelator, but was completely abolished by wortmannin, a PI3K inhibitor. RBP4 significantly increased p-Akt and p-eNOS production, and significantly inhibited p-ERK1/2 production. Triciribine, an Akt inhibitor, and wortmannin significantly inhibited RBP4-induced p-Akt and p-eNOS production. Inhibition of Akt1 by small interfering RNA decreased p-eNOS production enhanced by RBP4 in human umbilical vein endothelial cells. In conclusion, RBP4 has a robust acute effect of enhancement of NO production via stimulation of part of the PI3K/Akt/eNOS pathway and inhibition of ERK1/2 phosphorylation and insulin-induced ET-1 secretion, probably in the MAPK pathway, which results in vasodilatation.

MeSH terms

  • Animals
  • Cattle
  • Cell Line
  • Endothelin-1 / metabolism
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / metabolism
  • Endothelium, Vascular / physiology*
  • Humans
  • Insulin / pharmacology
  • Male
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase Type III / metabolism
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA, Small Interfering / genetics
  • Rats
  • Rats, Wistar
  • Retinol-Binding Proteins, Plasma / pharmacology
  • Retinol-Binding Proteins, Plasma / physiology*
  • Vasodilation*

Substances

  • Endothelin-1
  • Insulin
  • RBP4 protein, human
  • RNA, Small Interfering
  • Retinol-Binding Proteins, Plasma
  • Nitric Oxide
  • Nitric Oxide Synthase Type III
  • Proto-Oncogene Proteins c-akt
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3