Rapid nitration of adipocyte phosphoenolpyruvate carboxykinase by leptin reduces glyceroneogenesis and induces fatty acid release

PLoS One. 2012;7(7):e40650. doi: 10.1371/journal.pone.0040650. Epub 2012 Jul 11.

Abstract

Fatty acid (FA) release from white adipose tissue (WAT) is the result of the balance between triglyceride breakdown and FA re-esterification. The latter relies on the induction of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C), the key enzyme for glyceroneogenesis. We previously demonstrated that long-term (18 h) leptin treatment of rat epididymal WAT explants reduced glyceroneogenesis through nitric oxide (NO)-induced decrease in PEPCK-C expression. We investigated the effect of a short-term leptin treatment (2 h) on PEPCK-C expression and glyceroneogenesis in relation to NO production. We demonstrate that in WAT explants, leptin-induced NO synthase III (NOS III) phosphorylation was associated with reduced PEPCK-C level and glyceroneogenesis, leading to FA release, while PEPCK-C gene expression remained unaffected. These effects were absent in WAT explants from leptin receptor-deficient Zucker rat. Immunoprecipitation and western blot experiments showed that the leptin-induced decrease in PEPCK-C level was correlated with an increase in PEPCK-C nitration. All these effects were abolished by the NOS inhibitor Nω-nitro-L-arginine methyl ester and mimicked by the NO donor S-nitroso-N-acetyl-DL penicillamine. We propose a mechanism in which leptin activates NOS III and induces NO that nitrates PEPCK-C to reduce its level and glyceroneogenesis, therefore limiting FA re-esterification in WAT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipocytes / drug effects
  • Adipocytes / enzymology*
  • Adipocytes / metabolism*
  • Animals
  • Fatty Acids / metabolism*
  • Gene Expression Regulation / drug effects
  • Glycerol / metabolism*
  • Interferon-gamma / pharmacology
  • Leptin / pharmacology*
  • Lipolysis / drug effects
  • Male
  • NG-Nitroarginine Methyl Ester / pharmacology
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase Type II / genetics
  • Nitric Oxide Synthase Type II / metabolism
  • Nitric Oxide Synthase Type III / genetics
  • Nitric Oxide Synthase Type III / metabolism
  • Nitrosation / drug effects
  • Phosphoenolpyruvate Carboxykinase (ATP) / genetics
  • Phosphoenolpyruvate Carboxykinase (ATP) / metabolism*
  • Phosphorylation / drug effects
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Rats, Zucker

Substances

  • Fatty Acids
  • Leptin
  • RNA, Messenger
  • Nitric Oxide
  • Interferon-gamma
  • Nitric Oxide Synthase Type II
  • Nitric Oxide Synthase Type III
  • Phosphoenolpyruvate Carboxykinase (ATP)
  • Glycerol
  • NG-Nitroarginine Methyl Ester