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Effects of integrin-mediated cell adhesion on plasma membrane lipid raft components and signaling

Andrés Norambuena1, Martin A Schwartz

  • 1Robert M. Berne Cardiovascular Research Center, Mellon Urological Cancer Research Institute, University of Virginia, Charlottesville, VA 22908, USA.

Molecular Biology of the Cell
|July 29, 2011
PubMed

Insights

Cell adhesion loss triggers lipid raft changes, affecting growth signaling pathways. Specific proteins like flotillin2 and connexin43 remain membrane-bound, while Gα(s) detachment-induced cyclic adenosine monophosphate (cAMP) increase is blocked by modifying its lipid tail.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • Anchorage dependence regulates cell growth and prevents cancer metastasis.
  • Integrin signaling and lipid rafts are crucial for cell adhesion.
  • Previous studies focused on limited lipid raft markers like GM1.

Purpose of the Study:

  • To investigate the behavior of diverse lipid raft components upon cell detachment.
  • To elucidate the mechanism linking cell adhesion, lipid raft dynamics, and cyclic adenosine monophosphate (cAMP) production.

Main Methods:

  • Analyzing lipid raft component localization and fractionation using sucrose gradients after cell detachment.
  • Investigating the role of Gα(s) lipid tail modification in regulating cAMP levels.

Main Results:

  • Many raft components internalized upon detachment, but flotillin2, connexin43, and H-Ras remained associated with the plasma membrane.
  • Loss of adhesion caused raft components to shift to non-raft fractions, with flotillin2, connexin43, and H-Ras showing resistance.
  • Gα(s) lost raft association, correlating with increased cAMP; modifying Gα(s) lipid tail prevented this cAMP elevation.

Conclusions:

  • Integrin-mediated adhesion influences the localization and behavior of various lipid raft components.
  • The study reveals a mechanism for the previously observed increase in cAMP following cell detachment, involving Gα(s) raft dissociation.

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