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J Cell Biol. 2017 Feb;216(2):343-353. doi: 10.1083/jcb.201610060. Epub 2017 Jan 31.

Localization of mTORC2 activity inside cells.

Author information

1
Max F. Perutz Laboratories, Department of Structural and Computational Biology, Vienna BioCenter, 1030 Vienna, Austria.
2
Department of Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria.
3
Center for Molecular Biology, Student Services, University of Vienna, 1030 Vienna, Austria.
4
Vienna BioCenter Summer School Program, Division of Systems Biology of Signal Transduction, 69120 Heidelberg, Germany.
5
Max F. Perutz Laboratories, Department of Structural and Computational Biology, Vienna BioCenter, 1030 Vienna, Austria ivan.yudushkin@mfpl.ac.at.

Abstract

Activation of protein kinase Akt via its direct phosphorylation by mammalian target of rapamycin (mTOR) complex 2 (mTORC2) couples extracellular growth and survival cues with pathways controlling cell growth and proliferation, yet how growth factors target the activity of mTORC2 toward Akt is unknown. In this study, we examine the localization of the obligate mTORC2 component, mSin1, inside cells and report the development of a reporter to examine intracellular localization and regulation by growth factors of the endogenous mTORC2 activity. Using a combination of imaging and biochemical approaches, we demonstrate that inside cells, mTORC2 activity localizes to the plasma membrane, mitochondria, and a subpopulation of endosomal vesicles. We show that unlike the endosomal pool, the activity and localization of mTORC2 via the Sin1 pleckstrin homology domain at the plasma membrane is PI3K and growth factor independent. Furthermore, we show that membrane recruitment is sufficient for Akt phosphorylation in response to growth factors. Our results indicate the existence of spatially separated mTORC2 populations with distinct sensitivity to PI3K inside cells and suggest that intracellular localization could contribute to regulation of mTORC2 activity toward Akt.

PMID:
28143890
PMCID:
PMC5294791
DOI:
10.1083/jcb.201610060
[Indexed for MEDLINE]
Free PMC Article

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