Deletion of hepatic FoxO1/3/4 genes in mice significantly impacts on glucose metabolism through downregulation of gluconeogenesis and upregulation of glycolysis

PLoS One. 2013 Aug 28;8(8):e74340. doi: 10.1371/journal.pone.0074340. eCollection 2013.

Abstract

Forkhead transcription factors FoxO1/3/4 have pleiotrophic functions including anti-oxidative stress and metabolism. With regard to glucose metabolism, most studies have been focused on FoxO1. To further investigate their hepatic functions, we generated liver-specific FoxO1/3/4 knockout mice (LTKO) and examined their collective impacts on glucose homeostasis under physiological and pathological conditions. As compared to wild-type mice, LTKO mice had lower blood glucose levels under both fasting and non-fasting conditions and they manifested better glucose and pyruvate tolerance on regular chow diet. After challenged by a high-fat diet, wild-type mice developed type 2 diabetes, but LTKO mice remained euglycemic and insulin-sensitive. To understand the underlying mechanisms, we examined the roles of SIRT6 (Sirtuin 6) and Gck (glucokinase) in the FoxO-mediated glucose metabolism. Interestingly, ectopic expression of SIRT6 in the liver only reduced gluconeogenesis in wild-type but not LTKO mice whereas knockdown of Gck caused glucose intolerance in both wild-type and LTKO mice. The data suggest that both decreased gluconeogenesis and increased glycolysis may contribute to the overall glucose phenotype in the LTKO mice. Collectively, FoxO1/3/4 transcription factors play important roles in hepatic glucose homeostasis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Cycle Proteins
  • Dietary Fats / pharmacology
  • Forkhead Box Protein O1
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors / genetics
  • Forkhead Transcription Factors / metabolism*
  • Gene Deletion
  • Glucokinase / genetics
  • Glucokinase / metabolism
  • Gluconeogenesis / drug effects
  • Gluconeogenesis / physiology*
  • Glucose / genetics
  • Glucose / metabolism*
  • Glycolysis / drug effects
  • Glycolysis / physiology*
  • Homeostasis / drug effects
  • Homeostasis / physiology
  • Liver / metabolism*
  • Mice
  • Mice, Knockout
  • Organ Specificity / genetics
  • Sirtuins / genetics
  • Sirtuins / metabolism
  • Up-Regulation / drug effects
  • Up-Regulation / physiology

Substances

  • Cell Cycle Proteins
  • Dietary Fats
  • Forkhead Box Protein O1
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors
  • FoxO3 protein, mouse
  • FoxO4 protein, mouse
  • Foxo1 protein, mouse
  • Sirt6 protein, mouse
  • Glucokinase
  • Sirtuins
  • Glucose