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CAP defines a second signalling pathway required for insulin-stimulated glucose transport

C A Baumann1, V Ribon, M Kanzaki

  • 1Department of Physiology, University of Michigan School of Medicine, Ann Arbor, Michigan 48109, USA.

Nature
|September 23, 2000
PubMed

Insights

Insulin

Area of Science:

  • Cellular biology
  • Molecular mechanisms of insulin signaling

Background:

  • Insulin regulates glucose transport in fat and muscle cells.
  • The precise molecular mechanisms of insulin action are not fully understood.
  • Insulin receptor activation initiates intracellular signaling cascades.

Purpose of the Study:

  • To elucidate the molecular mechanisms underlying insulin-stimulated glucose transport.
  • To identify proteins involved in the insulin receptor signaling pathway.
  • To understand the role of Cbl and CAP proteins in insulin action.

Main Methods:

  • Yeast two-hybrid screening to identify protein interactions.
  • Biochemical assays to study protein complex formation and localization.
  • Cellular experiments using 3T3-L1 adipocytes to assess glucose uptake.

Main Results:

  • Identified flotillin as a binding partner for the CAP-Cbl complex.
  • Demonstrated that flotillin directs the CAP-Cbl complex to lipid rafts.
  • Showed that the CAP-Cbl complex localization to lipid rafts is essential for insulin-stimulated glucose uptake.
  • Discovered that blocking CAP localization inhibits insulin's effect on glucose transport without affecting phosphatidylinositol-3-OH kinase signaling.

Conclusions:

  • The Cbl-CAP complex, localized to lipid rafts via flotillin, is a critical component of insulin-regulated glucose transport.
  • This pathway represents a key mechanism for controlling glucose uptake in response to insulin.
  • Targeting this pathway could offer new strategies for managing glucose metabolism.

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