GSK3-mediated raptor phosphorylation supports amino acid-dependent Q2 mTORC1-directed signalling

Clare Stretton, Thorsten M. Hoffmann, Michael J. Munson, Alan Prescott, Peter M. Taylor, Ian G. Ganley, Harinder Hundal (Lead / Corresponding author)

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Abstract

The mammalian or mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) is a ubiquitously expressed multimeric protein kinase complex that integrates nutrient and growth factor signals for the co-ordinated regulation of cellular metabolism and cell growth. Herein, we demonstrate that suppressing the cellular activity of glycogen synthase kinase-3 (GSK3), by use of pharmacological inhibitors or shRNA-mediated gene silencing, results in substantial reduction in amino acid (AA)-regulated mTORC1-directed signalling, as assessed by phosphorylation of multiple downstream mTORC1 targets. We show that GSK3 regulates mTORC1 activity through its ability to phosphorylate the mTOR-associated scaffold protein raptor (regulatory-associated protein of mTOR) on Ser859. We further demonstrate that either GSK3 inhibition or expression of a S859A mutated raptor leads to reduced interaction between mTOR and raptor and under these circumstances, irrespective of AA availability, there is a consequential loss in phosphorylation of mTOR substrates, such as p70S6K1 (ribosomal S6 kinase 1) and uncoordinated-51-like kinase (ULK1), which results in increased autophagic flux and reduced cellular proliferation.
Original languageEnglish
Pages (from-to)207-221
JournalBiochemical Journal
Volume470
Issue number2
Early online date20 Aug 2015
DOIs
Publication statusPublished - 1 Sep 2015

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TOR Serine-Threonine Kinases
Glycogen Synthase Kinase 3
Phosphorylation
Sirolimus
Amino Acids
Ribosomal Protein S6 Kinases
Cell growth
Gene Silencing
Metabolism
Scaffolds
Protein Kinases
Small Interfering RNA
Nutrients
Intercellular Signaling Peptides and Proteins
Phosphotransferases
Genes
Cell Proliferation
Availability
Pharmacology
Fluxes

Cite this

Stretton, Clare ; Hoffmann, Thorsten M. ; Munson, Michael J. ; Prescott, Alan ; Taylor, Peter M. ; Ganley, Ian G. ; Hundal, Harinder. / GSK3-mediated raptor phosphorylation supports amino acid-dependent Q2 mTORC1-directed signalling. In: Biochemical Journal. 2015 ; Vol. 470, No. 2. pp. 207-221.
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GSK3-mediated raptor phosphorylation supports amino acid-dependent Q2 mTORC1-directed signalling. / Stretton, Clare; Hoffmann, Thorsten M.; Munson, Michael J.; Prescott, Alan; Taylor, Peter M.; Ganley, Ian G.; Hundal, Harinder (Lead / Corresponding author).

In: Biochemical Journal, Vol. 470, No. 2, 01.09.2015, p. 207-221.

Research output: Contribution to journalArticle

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