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Insulin acutely decreases hepatic fatty acid synthase activity

Sonia M Najjar1, Yan Yang, Mats A Fernström

  • 1Department of Pharmacology, Cardiovascular Biology and Metabolic Diseases, The Medical University of Ohio, 3035 Arlington Avenue, HSci Building, Room 270, Toledo, OH 43614, USA. snajjar@meduohio.edu

Cell Metabolism
|August 2, 2005
PubMed

Insights

Insulin acutely reduces liver fatty acid synthase (FAS) activity via CEACAM1 phosphorylation. This mechanism, dependent on prior insulin levels, regulates lipogenesis during refeeding.

Area of Science:

  • Metabolism
  • Molecular Biology
  • Hepatology

Background:

  • Insulin traditionally promotes fatty acid synthesis (FAS) by increasing FAS mRNA transcription.
  • A novel mechanism for insulin's acute regulation of hepatic FAS activity is investigated.

Purpose of the Study:

  • To elucidate a new pathway for insulin's rapid control of hepatic fatty acid synthase (FAS) activity.
  • To determine the role of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) in insulin signaling.

Main Methods:

  • Utilized Ceacam1 null (Cc1(-/-)) mice and primary hepatocytes.
  • Employed adenoviral delivery of wild-type and mutant CEACAM1.
  • Examined insulin's effect on FAS activity in hyperinsulinemic and obese mouse models.

Main Results:

  • Insulin acutely reduces hepatic FAS activity through CEACAM1 phosphorylation and interaction with FAS.
  • Cc1(-/-) mice lack insulin's acute effect on hepatic FAS activity.
  • Restoration of CEACAM1 function in Cc1(-/-) hepatocytes re-established insulin's acute effect.

Conclusions:

  • CEACAM1-mediated phosphorylation is crucial for insulin's acute suppression of hepatic FAS activity.
  • This pathway is essential for modulating hepatic lipogenesis in response to insulin pulses during refeeding.
  • The acute effect of insulin on FAS activity is contingent upon the preceding insulinemic state.

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