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 dominantnegative 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.Calastretti; A.Bevilacqua; I.D'Agnano; G.Gatti; G.Canti; D.Delia; S.Capaccioli; A.Nicolin. - In: ONCOGENE. - ISSN 0950-9232. - STAMPA. - 23:(2004), pp. 5781-5791. [10.1038/sj.onc.1207698]

BCL-2 PHOSPHORYLATION AND APOPTOSIS ACTIVATED BY DAMAGED MICROTUBULES REQUIRE MTOR AND ARE REGULATED BY AKT.

CAPACCIOLI, SERGIO;
2004

Abstract

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 dominantnegative 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.
2004
23
5781
5791
L.Asnaghi; A.Calastretti; A.Bevilacqua; I.D'Agnano; G.Gatti; G.Canti; D.Delia; S.Capaccioli; A.Nicolin
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/11827
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