Related Experiment Videos
Inhibition of v-src-induced transformation by a GTPase-activating protein
1Department of Microbiology, University of Virginia School of Medicine, Charlottesville 22908.
Abstract:
Previous work has shown that microinjection into cells of antibodies against p21ras blocks transformation by src, suggesting that oncogenic transformation by pp60v-src is dependent on p21ras. The activity of p21ras itself is regulated by its cyclic association with GDP-GTP, where p21ras-GTP is the active form and p21ras-GDP is the inactive form. A GTPase-activating protein (GAP) mediates the inactivation of p21ras by facilitating the conversion of the active p21ras-GTP to the inactive p21ras-GDP. This predicts that overexpression of GAP would inactivate p21ras and block transformation of cells by src. In this paper, we confirm this prediction. We report that overexpression of GAP in NIH 3T3 cells blocks transformation by pp60v-src but not by v-ras. Susceptibility to transformation by v-src is restored when GAP expression is lowered to levels comparable to that in control cells. These results support the suggestion that p21ras plays a central role in the signalling pathway used by pp60v-src.
Insights
Overexpressing GTPase-activating protein (GAP) inactivates p21ras, blocking oncogenic transformation by pp60v-src. This confirms p21ras
Area of Science:
- Molecular Biology
- Cellular Signaling
- Oncogenesis
Background:
- Oncogenic transformation by pp60v-src is suggested to depend on p21ras.
- p21ras activity is regulated by GTP/GDP binding, with p21ras-GTP being the active form.
- GTPase-activating protein (GAP) inactivates p21ras by promoting GTP hydrolysis.
Purpose of the Study:
- To investigate the role of GAP in pp60v-src-mediated oncogenic transformation.
- To confirm the prediction that GAP overexpression blocks src-induced transformation by inactivating p21ras.
Main Methods:
- Overexpression of GAP in NIH 3T3 cells.
- Assessing cellular transformation induced by pp60v-src and v-ras.
- Modulating GAP expression levels to observe effects on transformation.
Main Results:
- Overexpression of GAP blocked transformation induced by pp60v-src but not by v-ras.
- Reduced GAP expression restored susceptibility to v-src transformation.
- These findings support a central role for p21ras in the pp60v-src signaling pathway.
Conclusions:
- p21ras is a critical component in the signaling pathway utilized by pp60v-src for oncogenic transformation.
- GAP acts as a key negative regulator of p21ras activity in the context of src-induced transformation.