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PLoS One. 2010 Mar 9;5(3):e9616. doi: 10.1371/journal.pone.0009616.

Regulation of proapoptotic mammalian ste20-like kinase MST2 by the IGF1-Akt pathway.

Author information

1
Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA.

Abstract

BACKGROUND:

Hippo, a Drosophila serine/threonine kinase, promotes apoptosis and restricts cell growth and proliferation. Its mammalian homolog MST2 has been shown to play similar role and be regulated by Raf-1 via a kinase-independent mechanism and by RASSF family proteins through forming complex with MST2. However, regulation of MST2 by cell survival signal remains largely unknown.

METHODOLOGY/PRINCIPAL FINDINGS:

Using immunoblotting, in vitro kinase and in vivo labeling assays, we show that IGF1 inhibits MST2 cleavage and activation induced by DNA damage through the phosphatidylinosotol 3-kinase (PI3K)/Akt pathway. Akt phosphorylates a highly conserved threonine-117 residue of MST2 in vitro and in vivo, which leads to inhibition of MST2 cleavage, nuclear translocation, autophosphorylation-Thr180 and kinase activity. As a result, MST2 proapoptotic and growth arrest function was significantly reduced. Further, inverse correlation between pMST2-T117/pAkt and pMST2-T180 was observed in human breast tumors.

CONCLUSIONS/SIGNIFICANCE:

Our findings demonstrate for the first time that extracellular cell survival signal IGF1 regulates MST2 and that Akt is a key upstream regulator of MST2.

PMID:
20231902
PMCID:
PMC2834758
DOI:
10.1371/journal.pone.0009616
[Indexed for MEDLINE]
Free PMC Article

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