mTOR Ser-2481 autophosphorylation monitors mTORC-specific catalytic activity and clarifies rapamycin mechanism of action

Ghada Soliman, Hugo A. Acosta-Jaquez, Elaine A. Dunlop, Bilgen Ekim, Nicole E. Maj, Andrew R. Tee, Diane C. Fingar

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Abstract

The mammalian target of rapamycin (mTOR) Ser/Thr kinase signals in at least two multiprotein complexes distinguished by their different partners and sensitivities to rapamycin. Acute rapamycin inhibits signaling by mTOR complex 1 (mTORC1) but not mTOR complex 2 (mTORC2), which both promote cell growth, proliferation, and survival. Although mTORC2 regulation remains poorly defined, diverse cellular mitogens activate mTORC1 signaling in a manner that requires sufficient levels of amino acids and cellular energy. Before the identification of distinct mTOR complexes, mTOR was reported to autophosphorylate on Ser-2481 in vivo in a rapamycin- and amino acid-insensitive manner. These results suggested that modulation of mTOR intrinsic catalytic activity does not universally underlie mTOR regulation. Here we re-examine the regulation of mTOR Ser-2481 autophosphorylation (Ser(P)-2481) in vivo by studying mTORC-specific Ser(P)-2481 inmTORC1and mTORC2, with a primary focus on mTORC1. In contrast to previous work, we find that acute rapamycin and amino acid withdrawal markedly attenuate mTORC1-associated mTOR Ser(P)-2481 in cycling cells. Although insulin stimulates both mTORC1- and mTORC2-associated mTOR Ser(P)-2481 in a phosphatidylinositol 3-kinase-dependent manner, rapamycin acutely inhibits insulin-stimulated mTOR Ser(P)-2481 in mTORC1 but not mTORC2. By interrogating diverse mTORC1 regulatory input, we find that without exception mTORC1-activating signals promote, whereas mTORC1-inhibitory signals decrease mTORC1-associated mTOR Ser(P)-2481. These data suggest that mTORC1- and likely mTORC2-associated mTOR Ser-2481 autophosphorylation directly monitors intrinsic mTORC-specific catalytic activity and reveal that rapamycin inhibits mTORC1 signaling in vivo by reducing mTORC1 catalytic activity.

Original languageEnglish (US)
Pages (from-to)7866-7879
Number of pages14
JournalJournal of Biological Chemistry
Volume285
Issue number11
DOIs
StatePublished - Mar 12 2010

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Sirolimus
Catalyst activity
Amino Acids
Phosphatidylinositol 3-Kinase
Insulin
Multiprotein Complexes
Cell growth
Mitogens

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Soliman, G., Acosta-Jaquez, H. A., Dunlop, E. A., Ekim, B., Maj, N. E., Tee, A. R., & Fingar, D. C. (2010). mTOR Ser-2481 autophosphorylation monitors mTORC-specific catalytic activity and clarifies rapamycin mechanism of action. Journal of Biological Chemistry, 285(11), 7866-7879. https://doi.org/10.1074/jbc.M109.096222

mTOR Ser-2481 autophosphorylation monitors mTORC-specific catalytic activity and clarifies rapamycin mechanism of action. / Soliman, Ghada; Acosta-Jaquez, Hugo A.; Dunlop, Elaine A.; Ekim, Bilgen; Maj, Nicole E.; Tee, Andrew R.; Fingar, Diane C.

In: Journal of Biological Chemistry, Vol. 285, No. 11, 12.03.2010, p. 7866-7879.

Research output: Contribution to journalArticle

Soliman, G, Acosta-Jaquez, HA, Dunlop, EA, Ekim, B, Maj, NE, Tee, AR & Fingar, DC 2010, 'mTOR Ser-2481 autophosphorylation monitors mTORC-specific catalytic activity and clarifies rapamycin mechanism of action', Journal of Biological Chemistry, vol. 285, no. 11, pp. 7866-7879. https://doi.org/10.1074/jbc.M109.096222
Soliman, Ghada ; Acosta-Jaquez, Hugo A. ; Dunlop, Elaine A. ; Ekim, Bilgen ; Maj, Nicole E. ; Tee, Andrew R. ; Fingar, Diane C. / mTOR Ser-2481 autophosphorylation monitors mTORC-specific catalytic activity and clarifies rapamycin mechanism of action. In: Journal of Biological Chemistry. 2010 ; Vol. 285, No. 11. pp. 7866-7879.
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