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Interaction between Gab1 and the c-Met receptor tyrosine kinase is responsible for epithelial morphogenesis
K M Weidner1, S Di Cesare, M Sachs
1Max Delbrück Center for Molecular Medicine, Berlin, Germany.
Abstract:
The proteins Gab1 and the related DOS (for 'daughter of sevenless') each bind to substrates of tyrosine kinases like Grb2 or Corkscrew, and act in signalling pathways downstream of tyrosine kinase receptors. Here we show that Gab1 interacts directly with the c-met-encoded receptor tyrosine kinase but not with a number of other tyrosine kinases from different subfamilies. A newly identified proline-rich domain of Gab1 is responsible for the binding of this protein to the tyrosine-phosphorylated bidentate docking site in c-Met. Expression of Gab1 in epithelial cells is sufficient to induce the c-Met-specific activities, including branching morphogenesis. Thus we have discovered a new phosphotyrosine interaction domain in Gab1 and shown that Gab1 is the substrate of the c-Met receptor tyrosine kinase that mediates epithelial morphogenesis.
Insights
Gab1 directly binds to the c-Met receptor tyrosine kinase via a novel proline-rich domain. This interaction is crucial for Gab1 mediating c-Met
Area of Science:
- Cellular signaling pathways
- Receptor tyrosine kinases
- Epithelial biology
Background:
- Gab1 and DOS proteins are key adaptors in tyrosine kinase signaling.
- They bind substrates of tyrosine kinases like Grb2 and Corkscrew.
- These proteins act downstream of tyrosine kinase receptors.
Purpose of the Study:
- To investigate the interaction between Gab1 and the c-Met receptor tyrosine kinase.
- To identify the specific domains involved in this interaction.
- To elucidate Gab1's role in c-Met-mediated epithelial morphogenesis.
Main Methods:
- Co-immunoprecipitation assays to confirm protein interactions.
- Site-directed mutagenesis to identify functional domains.
- Expression studies in epithelial cells to assess functional consequences.
Main Results:
- Gab1 directly interacts with the c-Met receptor tyrosine kinase.
- A newly identified proline-rich domain in Gab1 mediates binding to c-Met's docking site.
- Gab1 expression in epithelial cells induced c-Met-specific branching morphogenesis.
Conclusions:
- Gab1 possesses a novel phosphotyrosine interaction domain.
- Gab1 acts as a direct substrate of the c-Met receptor tyrosine kinase.
- Gab1 is essential for mediating c-Met-driven epithelial morphogenesis.