Insulin activates hepatic Wnt/β-catenin signaling through stearoyl-CoA desaturase 1 and Porcupine

Sci Rep. 2020 Mar 20;10(1):5186. doi: 10.1038/s41598-020-61869-4.

Abstract

The Wnt/β-catenin pathway plays a pivotal role in liver structural and metabolic homeostasis. Wnt activity is tightly regulated by the acyltransferase Porcupine through the addition of palmitoleate. Interestingly palmitoleate can be endogenously produced by the stearoyl-CoA desaturase 1 (SCD1), a lipogenic enzyme transcriptionally regulated by insulin. This study aimed to determine whether nutritional conditions, and insulin, regulate Wnt pathway activity in liver. An adenoviral TRE-Luciferase reporter was used as a readout of Wnt/β-catenin pathway activity, in vivo in mouse liver and in vitro in primary hepatocytes. Refeeding enhanced TRE-Luciferase activity and expression of Wnt target genes in mice liver, revealing a nutritional regulation of the Wnt/β-catenin pathway. This effect was inhibited in liver specific insulin receptor KO (iLIRKO) mice and upon wortmannin or rapamycin treatment. Overexpression or inhibition of SCD1 expression regulated Wnt/β-catenin activity in primary hepatocytes. Similarly, palmitoleate added exogenously or produced by SCD1-mediated desaturation of palmitate, induced Wnt signaling activity. Interestingly, this effect was abolished in the absence of Porcupine, suggesting that both SCD1 and Porcupine are key mediators of insulin-induced Wnt/β-catenin activity in hepatocytes. Altogether, our findings suggest that insulin and lipogenesis act as potential novel physiological inducers of hepatic Wnt/β-catenin pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / metabolism
  • Animals
  • Fatty Acids, Monounsaturated / pharmacology
  • Hepatocytes / metabolism
  • Insulin / metabolism*
  • Lipogenesis / drug effects
  • Liver / metabolism
  • Liver / pathology
  • Male
  • Membrane Proteins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Stearoyl-CoA Desaturase / genetics
  • Stearoyl-CoA Desaturase / metabolism
  • Sterol Regulatory Element Binding Protein 1 / metabolism
  • Wnt Signaling Pathway / drug effects*
  • Wnt Signaling Pathway / physiology
  • beta Catenin / drug effects*
  • beta Catenin / metabolism

Substances

  • Fatty Acids, Monounsaturated
  • Insulin
  • Membrane Proteins
  • Sterol Regulatory Element Binding Protein 1
  • beta Catenin
  • palmitoleic acid
  • Scd1 protein, mouse
  • Stearoyl-CoA Desaturase
  • Acyltransferases
  • Porcn protein, mouse