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Suppression of integrin activation: a novel function of a Ras/Raf-initiated MAP kinase pathway

P E Hughes1, M W Renshaw, M Pfaff

  • 1Department of Vascular Biology, The Scripps Research Institute, La Jolla, California 92037, USA.

Cell
|February 21, 1997
PubMed

Insights

The study reveals that H-Ras and Raf-1 negatively regulate integrin activation, a key cell adhesion process. This regulation is transcription-independent and linked to the ERK MAP kinase pathway, suggesting a novel feedback mechanism.

Area of Science:

  • Cell Adhesion Biology
  • Signal Transduction
  • Molecular Cell Biology

Background:

  • Integrins are crucial cell adhesion receptors that rapidly modulate ligand binding affinity, a process termed activation.
  • Understanding the regulation of integrin activation is vital for comprehending cell-cell and cell-matrix interactions.

Purpose of the Study:

  • To identify novel regulators of integrin activation.
  • To elucidate the molecular mechanisms underlying integrin affinity modulation.

Main Methods:

  • Conducted a screen for suppressors of integrin activation.
  • Investigated the role of H-Ras and its effector kinase, Raf-1.
  • Assessed the impact on integrin phosphorylation, mRNA transcription, and protein synthesis.
  • Correlated suppression with ERK MAP kinase pathway activation.

Main Results:

  • Identified H-Ras and Raf-1 as negative regulators of integrin activation.
  • Demonstrated that H-Ras inhibits integrin activation across different subunit combinations.
  • Found that suppression is independent of integrin phosphorylation, transcription, and protein synthesis.
  • Showed a correlation between H-Ras-mediated suppression and ERK MAP kinase pathway activation.

Conclusions:

  • Integrin affinity state is regulated by a novel, transcription-independent function of a Ras-linked MAP kinase pathway.
  • This pathway, involving H-Ras and ERK MAP kinase, may act as a negative feedback loop in integrin function.
  • Provides new insights into the complex signaling networks controlling cell adhesion.

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