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Mammalian Grb2 regulates multiple steps in embryonic development and malignant transformation
A M Cheng1, T M Saxton, R Sakai
1Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
Cell
|December 29, 1998
Summary
The adaptor protein Grb2 is essential for embryonic development and cancer. Genetic studies show Grb2 is required for endodermal cell differentiation and epiblast formation, linking it to the Ras signaling pathway.
Area of Science:
- Molecular Biology
- Developmental Biology
- Cell Signaling
Background:
- Proteins with SH2 and SH3 domains are crucial for signal transduction, linking tyrosine kinases to intracellular pathways.
- Adaptor proteins play key roles in mediating these signaling events.
- The specific functions of mammalian SH2/SH3 adaptors like Grb2 in development and disease require further elucidation.
Purpose of the Study:
- To investigate the biological functions of the mammalian SH2/SH3 adaptor Grb2.
- To determine the role of Grb2 in embryogenesis and cancer.
- To provide genetic evidence for the Grb2-Ras signaling pathway.
Main Methods:
- Introduction of a null mutation into the mouse gene for Grb2.
- Analysis of mutant embryonic stem cells, embryos, and chimeras.
- Creation of a fusion protein to assess Grb2's adaptor function and rescue capabilities.
Main Results:
- Grb2 is essential for endodermal cell differentiation and epiblast formation during embryogenesis.
- Grb2 acts as a physiological adaptor, with its SH2 domain partially rescuing Grb2-deficient phenotypes when fused to Sos1.
- Grb2 is rate-limiting for polyomavirus middle T antigen-induced mammary carcinomas.
Conclusions:
- Grb2 is indispensable for multiple aspects of mammalian embryogenesis.
- Genetic evidence supports a Grb2-Ras signaling pathway mediated by SH2/SH3 domain interactions.
- This pathway has critical roles in both embryonic development and the pathogenesis of cancer.
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