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Updated: May 23, 2026
09:58
RhoC GTPase Activation Assay
Published on: August 22, 2010
Grb2 mediates semaphorin-4D-dependent RhoA inactivation.
Tianliang Sun1, Rameshkumar Krishnan, Jakub M Swiercz
1Department of Pharmacology, Max-Planck Institute for Heart and Lung Research, Ludwigstr 43, 61231 Bad Nauheim, Germany.
Journal of Cell Science
|April 17, 2012
Summary
Semaphorin 4D (Sema4D) signaling uses plexin-B1 to control cell migration. We found that growth factor receptor bound-2 (Grb2) links plexin-B1 to RhoA inactivation, inhibiting breast cancer cell migration.
Area of Science:
- Cellular signaling pathways
- Receptor tyrosine kinases
- Cell migration regulation
Background:
- Semaphorin 4D (Sema4D) signaling via plexin-B1 is modulated by ErbB-2 and Met tyrosine kinases.
- Sema4D signaling can either promote or inhibit cell migration depending on receptor complex composition.
Purpose of the Study:
- To elucidate the mechanism by which plexin-B1 phosphorylation regulates RhoGTPase-activating protein (RhoGAP) interaction and activity.
- To identify the molecular link between plexin-B1 activation, RhoA inactivation, and Sema4D-mediated inhibition of cell migration.
Main Methods:
- Investigated receptor-ligand interactions using cell-based assays.
- Analyzed protein-protein interactions via co-immunoprecipitation and Western blotting.
- Assessed the role of specific protein domains (SH2, SH3) in signaling complex formation.
- Evaluated the impact of signaling pathway modulation on breast cancer cell migration.
Main Results:
- Sema4D activation of plexin-B1, followed by Met-mediated tyrosine phosphorylation, creates a docking site for growth factor receptor bound-2 (Grb2).
- Grb2 is recruited to the plexin-B1 complex and links it to p190 RhoGAP, leading to RhoA deactivation.
- This Grb2-mediated pathway is crucial for Sema4D-induced inhibition of breast cancer cell migration, without affecting plexin-B1's R-RasGAP activity.
Conclusions:
- Growth factor receptor bound-2 (Grb2) acts as a direct molecular bridge between plexin-B1 and p190 RhoGAP.
- This signaling axis is essential for the antimigratory effects of Sema4D in breast cancer cells.
- The findings reveal a novel mechanism controlling RhoA-dependent cell migration through receptor tyrosine kinase-mediated scaffolding.
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