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P120-GAP associated with syndecan-2 to function as an active switch signal for Src upon transformation with oncogenic

Jin-Wen Huang1, Chia-Lin Chen, Nin-Nin Chuang

  • 1Division of Biochemistry and Molecular Science, Institute of Zoology, Academia Sinica, Nankang, 11529 Taipei, Taiwan.

Biochemical and Biophysical Research Communications
|March 9, 2005
PubMed

Insights

Shrimp oncogenic ras transformation activates p120-GAP/syndecan-2 complex formation at caveolae. This complex activates Src tyrosine kinase, promoting tumor growth.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Oncogenic Ras proteins are key drivers of cellular transformation and cancer.
  • Caveolae are specialized membrane microdomains involved in signal transduction.
  • p120-GAP and syndecan-2 are proteins implicated in cellular signaling pathways.

Purpose of the Study:

  • To investigate the role of p120-GAP/syndecan-2 complex in oncogenic Ras-mediated cellular transformation.
  • To elucidate the molecular interactions and localization of the p120-GAP/syndecan-2 complex.
  • To determine the effect of this complex on Src tyrosine kinase activity.

Main Methods:

  • Transfection of BALB/3T3 cells with shrimp oncogenic Ras.
  • Affinity purification of p120-GAP and expression of fusion proteins.
  • Co-immunoprecipitation and Western blotting to assess protein interactions.
  • Localization studies using immunofluorescence microscopy.

Main Results:

  • A complex of p120-GAP and syndecan-2 was highly expressed upon transformation with shrimp oncogenic Ras.
  • The p120-GAP/syndecan-2 complex localized to caveolae, interacting with caveolin-1.
  • Molecular affinities were confirmed between p120-GAP, syndecan-2, and RACK1.
  • The p120-GAP/syndecan-2 complex activated Src tyrosine kinase, while the syndecan-2/RACK1 complex inactivated it.

Conclusions:

  • The p120-GAP/syndecan-2 complex at caveolae acts as a docking site for Src, facilitating tyrosine signaling.
  • Syndecan-2/p120-GAP functions as a tumor promoter in the context of shrimp oncogenic Ras transformation.
  • These findings offer insights into the molecular mechanisms of Ras-driven tumorigenesis.

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