Sin1 phosphorylation impairs mTORC2 complex integrity and inhibits downstream Akt signalling to suppress tumorigenesis Academic Article uri icon

Overview

MeSH Major

  • Adaptor Proteins, Signal Transducing
  • Carcinogenesis
  • Multiprotein Complexes
  • Proto-Oncogene Proteins c-akt
  • Signal Transduction
  • TOR Serine-Threonine Kinases

abstract

  • The mechanistic target of rapamycin (mTOR) functions as a critical regulator of cellular growth and metabolism by forming multi-component, yet functionally distinct complexes mTORC1 and mTORC2. Although mTORC2 has been implicated in mTORC1 activation, little is known about how mTORC2 is regulated. Here we report that phosphorylation of Sin1 at Thr 86 and Thr 398 suppresses mTORC2 kinase activity by dissociating Sin1 from mTORC2. Importantly, Sin1 phosphorylation, triggered by S6K or Akt, in a cellular context-dependent manner, inhibits not only insulin- or IGF-1-mediated, but also PDGF- or EGF-induced Akt phosphorylation by mTORC2, demonstrating a negative regulation of mTORC2 independent of IRS-1 and Grb10. Finally, a cancer-patient-derived Sin1-R81T mutation impairs Sin1 phosphorylation, leading to hyper-activation of mTORC2 by bypassing this negative regulation. Together, our results reveal a Sin1-phosphorylation-dependent mTORC2 regulation, providing a potential molecular mechanism by which mutations in the mTORC1-S6K-Sin1 signalling axis might cause aberrant hyper-activation of the mTORC2-Akt pathway, which facilitates tumorigenesis.

publication date

  • November 2013

Research

keywords

  • Academic Article

Identity

Language

  • eng

PubMed Central ID

  • PMC3827117

Digital Object Identifier (DOI)

  • 10.1038/ncb2860

PubMed ID

  • 24161930

Additional Document Info

start page

  • 1340

end page

  • 50

volume

  • 15

number

  • 11