The serine/threonine kinase mTOR, the major sensor of cell growth along the PI3K/Akt pathway, can be activated by agents acting on microtubules. Damaged microtubules induce phosphorylation of the Bcl-2 protein and lower the threshold of programmed cell death, both of which are inhibited by rapamycin. In HEK293 cells expressing Akt mutants, the level of Bcl-2 phosphorylation and the threshold of apoptosis induced by taxol or by nocodazole are significantly modified. In cells expressing dominant-negative Akt (DN-Akt), Bcl-2 phosphorylation and p70S6KThr421/Ser424 phosphorylation induced by taxol or nocodazole were significantly enhanced as compared to cells expressing constitutively active Akt (CA-Akt) and inhibited by rapamycin. Moreover, DN-Akt cells were more sensitive to antitubule agents than CA-Akt cells. In nocodazole-treated HEK293 cells sorted according to cell cycle, the p70S6KThr421/Ser424 phosphorylation was associated to the G2/M fraction. More relevant, nocodazole inhibited, in a dose–response manner, mTOR phosphorylation at Ser2448. This activity, potentiated in DN-Akt cells, was not detectable in CA-Akt cells. Our results suggest that death signals originating from damaged microtubules in G2/M can compete with G1 survival pathways at the level of mTOR. These findings have implications for cancer therapy and drug resistance.
Bcl-2 phosphorylation and apoptosis activated by damaged microtubules require mTOR and are regulated by Akt / L. Asnaghi, A.L. Calastretti, A.T. Bevilacqua, I. D’agnano, G. Gatti, G. Canti, S. Capaccioli, A.N. Nicolin. - In: ONCOGENE. - ISSN 0950-9232. - 23:34(2004), pp. 5781-5791.
|Titolo:||Bcl-2 phosphorylation and apoptosis activated by damaged microtubules require mTOR and are regulated by Akt|
CALASTRETTI, ANGELA LUISA (Secondo)
NICOLIN, ANGELO NICOLO' (Ultimo)
|Settore Scientifico Disciplinare:||Settore BIO/14 - Farmacologia|
|Data di pubblicazione:||2004|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1038/sj.onc.1207698|
|Appare nelle tipologie:||01 - Articolo su periodico|