Phosphorylation of FOXO3a on Ser-7 by p38 Promotes Its Nuclear Localization in Response to Doxorubicin

Ho, Ka-Kei; McGuire, Victoria A.; Koo, Chuay-Yeng; Muir, Kyle W.; de Olano, Natalia; Maifoshie, Evie; Kelly, Douglas J.; McGovern, Ursula B.; Monteiro, Lara J.; Gomes, Ana R.; Nebreda, Angel R.; Campbell, David G.; Arthur, J. Simon C.; Lam, Eric W. -F.


FOXO3a is a forkhead transcription factor that regulates a multitude of important cellular processes, including proliferation, apoptosis, differentiation, and metabolism. Doxorubicin treatment of MCF-7 breast carcinoma cells results in FOXO3a nuclear relocation and the induction of the stress-activated kinase p38 MAPK. Here, we studied the potential regulation of FOXO3a by p38 in response to doxorubicin. Co-immunoprecipitation studies in MCF-7 cells demonstrated a direct interaction between p38 and FOXO3a. We also showed that p38 can bind and phosphorylate a recombinant FOXO3a directly in vitro. HPLC-coupled phosphopeptide mapping and mass spectrometric analyses identified serine 7 as a major site for p38 phosphorylation. Using a phosphorylated Ser-7 FOXO3a antibody, we demonstrated that FOXO3a is phosphorylated on Ser-7 in response to doxorubicin. Immunofluorescence staining studies showed that upon doxorubicin treatment, the wild-type FOXO3a relocalized to the nucleus, whereas the phosphorylation-defective FOXO3a (Ala-7) mutant remained largely in the cytoplasm. Treatment with SB202190 also inhibits the doxorubicin-induced FOXO3a Ser-7 phosphorylation and nuclear accumulation in MCF-7 cells. In addition, doxorubicin caused the nuclear translocation of FOXO3a in wild-type but not p38-depleted mouse fibroblasts. Together, our results suggest that p38 phosphorylation of FOXO3a on Ser-7 is essential for its nuclear relocalization in response to doxorubicin.

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Título según WOS: ID WOS:000299170300068 Not found in local WOS DB
Volumen: 287
Número: 2
Editorial: Elsevier
Fecha de publicación: 2012
Página de inicio: 1545
Página final: 1555


Notas: ISI