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Updated: Jun 9, 2026

Measuring the Rate of Lipolysis in Ex Vivo Murine Adipose Tissue and Primary Preadipocytes Differentiated In Vitro
09:41

Measuring the Rate of Lipolysis in Ex Vivo Murine Adipose Tissue and Primary Preadipocytes Differentiated In Vitro

Published on: March 17, 2023

Insulin regulates adipocyte lipolysis via an Akt-independent signaling pathway

Sarah M Choi1, David F Tucker, Danielle N Gross

  • 1Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.

Molecular and Cellular Biology
|August 25, 2010
PubMed

Insights

Insulin normally suppresses fat breakdown (lipolysis) via Akt kinase. A new pathway shows insulin regulates lipolysis through localized protein kinase A (PKA) signaling, independent of Akt, impacting insulin resistance.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Metabolic Research

Background:

  • Insulin normally inhibits lipolysis (fat breakdown) by activating Akt kinase, which inhibits protein kinase A (PKA).
  • Insulin resistance impairs this process, contributing to dyslipidemia, obesity, and worsened insulin action.
  • Existing models focus on Akt-dependent regulation of lipolysis.

Purpose of the Study:

  • To investigate a novel, noncanonical pathway by which insulin regulates adipocyte lipolysis.
  • To explore the role of phosphoinositide-3 kinase (PI3K) and subcellular signaling in insulin's control of lipolysis.
  • To differentiate the regulation of PKA substrates during insulin action.

Main Methods:

  • Investigated Akt-independent, PI3K-dependent signaling in adipocytes.
  • Analyzed the subcellular localization of signaling pathways.
  • Examined the phosphorylation of PKA substrates, including perilipin and hormone-sensitive lipase (HSL).

Main Results:

  • Identified a noncanonical Akt-independent, PI3K-dependent pathway regulating lipolysis.
  • Demonstrated selective alteration of perilipin phosphorylation by PKA via this pathway.
  • Showed that HSL phosphorylation remains Akt-dependent, while total PKA activity is Akt-dependent.
  • Revealed spatially compartmentalized modulation of PKA by insulin.

Conclusions:

  • Insulin regulates adipocyte lipolysis through spatially compartmentalized modulation of PKA.
  • This Akt-independent pathway selectively impacts PKA substrate phosphorylation, offering new insights into insulin resistance.
  • Findings highlight the importance of localized signaling in metabolic regulation.

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