Proposed involvement of adipocyte glyceroneogenesis and phosphoenolpyruvate carboxykinase in the metabolic syndrome

Biochimie. 2005 Jan;87(1):27-32. doi: 10.1016/j.biochi.2004.12.005.

Abstract

Elevated concentration of plasma non-esterified fatty acids (NEFA) is now recognized as a key factor in the onset of insulin-resistance and type 2 diabetes mellitus. During fasting, circulating NEFAs arise from white adipose tissue (WAT) as a consequence of lipolysis from stored triacylglycerols. However, a significant part of these FAs (30-70%) is re-esterified within the adipocyte, so that a recycling occurs and net FA output is much less than << true >> lipolysis. Indeed, a balance between two antagonistic processes, lipolysis and FA re-esterification, controls the rate of net FA release from WAT. During fasting, re-esterification requires glyceroneogenesis defined as the de novo synthesis of glycerol-3-P from pyruvate, lactate or certain amino acids. The key enzyme in this process is the cytosolic isoform of phosphoenolpyruvate carboxykinase (PEPCK-C; EC 4.1.1.32). Recent advance has stressed the role of glyceroneogenesis and of PEPCK-C in FA release from WAT. Results indicate that glyceroneogenesis is indeed important to lipid homeostasis and that a disregulation in this pathway may have profound pathophysiological effects. The present review focuses on the regulation of glyceroneogenesis and of PEPCK-C gene expression and activity by FAs, retinoic acids, glucocorticoids and the hypolipidemic class of drugs, thiazolidinediones.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adipocytes / metabolism*
  • Adrenal Cortex Hormones / pharmacology
  • Animals
  • Esterification
  • Fatty Acids, Nonesterified / blood
  • Gene Expression Regulation, Enzymologic / drug effects
  • Glycerol / blood
  • Glycerol / metabolism
  • Glycerophosphates / biosynthesis*
  • Humans
  • Hypolipidemic Agents / pharmacology
  • Metabolic Syndrome / enzymology
  • Metabolic Syndrome / metabolism*
  • Mice
  • Phosphoenolpyruvate Carboxykinase (GTP) / biosynthesis
  • Phosphoenolpyruvate Carboxykinase (GTP) / metabolism*
  • Thiazoles / pharmacology
  • Thiazolidinediones
  • Tretinoin / pharmacology
  • Triglycerides / metabolism

Substances

  • Adrenal Cortex Hormones
  • Fatty Acids, Nonesterified
  • Glycerophosphates
  • Hypolipidemic Agents
  • Thiazoles
  • Thiazolidinediones
  • Triglycerides
  • thiazolidine-2,4-dione
  • Tretinoin
  • Phosphoenolpyruvate Carboxykinase (GTP)
  • Glycerol