| First Author | Yang JY | Year | 2005 |
| Journal | Mol Biol Cell | Volume | 16 |
| Issue | 8 | Pages | 3511-20 |
| PubMed ID | 15901831 | Mgi Jnum | J:101469 |
| Mgi Id | MGI:3604067 | Doi | 10.1091/mbc.E05-01-0080 |
| Citation | Yang JY, et al. (2005) Impaired Akt activity down-modulation, caspase-3 activation, and apoptosis in cells expressing a caspase-resistant mutant of RasGAP at position 157. Mol Biol Cell 16(8):3511-20 |
| abstractText | RasGAP bears two caspase-3 cleavage sites that are used sequentially as caspase activity increases in cells. When caspase-3 is mildly activated, RasGAP is first cleaved at position 455. This leads to the production of an N-terminal fragment, called fragment N, that activates the Ras-PI3K-Akt pathway and that promotes cell survival. At higher caspase activity, RasGAP is further cleaved at position 157 generating two small N-terminal fragments named N1 and N2. We have now determined the contribution of this second cleavage event in the regulation of apoptosis using cells in which the wild-type RasGAP gene has been replaced by a cDNA encoding a RasGAP mutant that cannot be cleaved at position 157. Our results show that cleavage of fragment N at position 157 leads to a marked reduction in Akt activity. This is accompanied by efficient processing of caspase-3 that favors cell death in response to various apoptotic stimuli. In nontumorigenic cells, fragments N1 and N2 do not modulate apoptosis. Therefore, the role of the second caspase-mediated cleavage of RasGAP is to allow the inactivation of the antiapoptotic function of fragment N so that caspases are no longer hampered in their ability to kill cells. |
