Site-specific mTOR phosphorylation promotes mTORC1-mediated signaling and cell growth

Hugo A. Acosta-Jaquez, Jennifer A. Keller, Kathryn G. Foster, Bilgen Ekim, Ghada A. Soliman, Edward P. Feener, Bryan A. Ballif, Diane C. Fingar

Research output: Contribution to journalArticle

92 Citations (Scopus)

Abstract

The mammalian target of rapamycin (mTOR) complex 1 (mTORC1) functions as a rapamycin-sensitive environmental sensor that promotes cellular biosynthetic processes in response to growth factors and nutrients. While diverse physiological stimuli modulate mTORC1 signaling, the direct biochemical mechanisms underlying mTORC1 regulation remain poorly defined. Indeed, while three mTOR phosphorylation sites have been reported, a functional role for site-specific mTOR phosphorylation has not been demonstrated. Here we identify a new site of mTOR phosphorylation (S1261) by tandem mass spectrometry and demonstrate that insulin-phosphatidylinositol 3-kinase signaling promotes mTOR S1261 phosphorylation in both mTORC1 and mTORC2. Here we focus on mTORC1 and show that TSC/Rheb signaling promotes mTOR S1261 phosphorylation in an amino acid-dependent, rapamycin-insensitive, and autophosphorylation-independent manner. Our data reveal a functional role for mTOR S1261 phosphorylation in mTORC1 action, as S1261 phosphorylation promotes mTORC1-mediated substrate phosphorylation (e.g., p70 ribosomal protein S6 kinase 1 [S6K1] and eukaryotic initiation factor 4E binding protein 1) and cell growth to increased cell size. Moreover, Rheb-driven mTOR S2481 autophosphorylation and S6K1 phosphorylation require S1261 phosphorylation. These data provide the first evidence that site-specific mTOR phosphorylation regulates mTORC1 function and suggest a model whereby insulin-stimulated mTOR S1261 phosphorylation promotes mTORC1 autokinase activity, substrate phosphorylation, and cell growth.

Original languageEnglish (US)
Pages (from-to)4308-4324
Number of pages17
JournalMolecular and cellular biology
Volume29
Issue number15
DOIs
StatePublished - Aug 1 2009

Fingerprint

Sirolimus
Phosphorylation
Growth
Ribosomal Protein S6 Kinases
Eukaryotic Initiation Factor-4E
Phosphatidylinositol 3-Kinase
Insulin
Tandem Mass Spectrometry
Cell Size
Intercellular Signaling Peptides and Proteins
Carrier Proteins

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

Acosta-Jaquez, H. A., Keller, J. A., Foster, K. G., Ekim, B., Soliman, G. A., Feener, E. P., ... Fingar, D. C. (2009). Site-specific mTOR phosphorylation promotes mTORC1-mediated signaling and cell growth. Molecular and cellular biology, 29(15), 4308-4324. https://doi.org/10.1128/MCB.01665-08

Site-specific mTOR phosphorylation promotes mTORC1-mediated signaling and cell growth. / Acosta-Jaquez, Hugo A.; Keller, Jennifer A.; Foster, Kathryn G.; Ekim, Bilgen; Soliman, Ghada A.; Feener, Edward P.; Ballif, Bryan A.; Fingar, Diane C.

In: Molecular and cellular biology, Vol. 29, No. 15, 01.08.2009, p. 4308-4324.

Research output: Contribution to journalArticle

Acosta-Jaquez, HA, Keller, JA, Foster, KG, Ekim, B, Soliman, GA, Feener, EP, Ballif, BA & Fingar, DC 2009, 'Site-specific mTOR phosphorylation promotes mTORC1-mediated signaling and cell growth', Molecular and cellular biology, vol. 29, no. 15, pp. 4308-4324. https://doi.org/10.1128/MCB.01665-08
Acosta-Jaquez HA, Keller JA, Foster KG, Ekim B, Soliman GA, Feener EP et al. Site-specific mTOR phosphorylation promotes mTORC1-mediated signaling and cell growth. Molecular and cellular biology. 2009 Aug 1;29(15):4308-4324. https://doi.org/10.1128/MCB.01665-08
Acosta-Jaquez, Hugo A. ; Keller, Jennifer A. ; Foster, Kathryn G. ; Ekim, Bilgen ; Soliman, Ghada A. ; Feener, Edward P. ; Ballif, Bryan A. ; Fingar, Diane C. / Site-specific mTOR phosphorylation promotes mTORC1-mediated signaling and cell growth. In: Molecular and cellular biology. 2009 ; Vol. 29, No. 15. pp. 4308-4324.
@article{0e255fcade3b419982ae78c687535039,
title = "Site-specific mTOR phosphorylation promotes mTORC1-mediated signaling and cell growth",
abstract = "The mammalian target of rapamycin (mTOR) complex 1 (mTORC1) functions as a rapamycin-sensitive environmental sensor that promotes cellular biosynthetic processes in response to growth factors and nutrients. While diverse physiological stimuli modulate mTORC1 signaling, the direct biochemical mechanisms underlying mTORC1 regulation remain poorly defined. Indeed, while three mTOR phosphorylation sites have been reported, a functional role for site-specific mTOR phosphorylation has not been demonstrated. Here we identify a new site of mTOR phosphorylation (S1261) by tandem mass spectrometry and demonstrate that insulin-phosphatidylinositol 3-kinase signaling promotes mTOR S1261 phosphorylation in both mTORC1 and mTORC2. Here we focus on mTORC1 and show that TSC/Rheb signaling promotes mTOR S1261 phosphorylation in an amino acid-dependent, rapamycin-insensitive, and autophosphorylation-independent manner. Our data reveal a functional role for mTOR S1261 phosphorylation in mTORC1 action, as S1261 phosphorylation promotes mTORC1-mediated substrate phosphorylation (e.g., p70 ribosomal protein S6 kinase 1 [S6K1] and eukaryotic initiation factor 4E binding protein 1) and cell growth to increased cell size. Moreover, Rheb-driven mTOR S2481 autophosphorylation and S6K1 phosphorylation require S1261 phosphorylation. These data provide the first evidence that site-specific mTOR phosphorylation regulates mTORC1 function and suggest a model whereby insulin-stimulated mTOR S1261 phosphorylation promotes mTORC1 autokinase activity, substrate phosphorylation, and cell growth.",
author = "Acosta-Jaquez, {Hugo A.} and Keller, {Jennifer A.} and Foster, {Kathryn G.} and Bilgen Ekim and Soliman, {Ghada A.} and Feener, {Edward P.} and Ballif, {Bryan A.} and Fingar, {Diane C.}",
year = "2009",
month = "8",
day = "1",
doi = "10.1128/MCB.01665-08",
language = "English (US)",
volume = "29",
pages = "4308--4324",
journal = "Molecular and Cellular Biology",
issn = "0270-7306",
publisher = "American Society for Microbiology",
number = "15",

}

TY - JOUR

T1 - Site-specific mTOR phosphorylation promotes mTORC1-mediated signaling and cell growth

AU - Acosta-Jaquez, Hugo A.

AU - Keller, Jennifer A.

AU - Foster, Kathryn G.

AU - Ekim, Bilgen

AU - Soliman, Ghada A.

AU - Feener, Edward P.

AU - Ballif, Bryan A.

AU - Fingar, Diane C.

PY - 2009/8/1

Y1 - 2009/8/1

N2 - The mammalian target of rapamycin (mTOR) complex 1 (mTORC1) functions as a rapamycin-sensitive environmental sensor that promotes cellular biosynthetic processes in response to growth factors and nutrients. While diverse physiological stimuli modulate mTORC1 signaling, the direct biochemical mechanisms underlying mTORC1 regulation remain poorly defined. Indeed, while three mTOR phosphorylation sites have been reported, a functional role for site-specific mTOR phosphorylation has not been demonstrated. Here we identify a new site of mTOR phosphorylation (S1261) by tandem mass spectrometry and demonstrate that insulin-phosphatidylinositol 3-kinase signaling promotes mTOR S1261 phosphorylation in both mTORC1 and mTORC2. Here we focus on mTORC1 and show that TSC/Rheb signaling promotes mTOR S1261 phosphorylation in an amino acid-dependent, rapamycin-insensitive, and autophosphorylation-independent manner. Our data reveal a functional role for mTOR S1261 phosphorylation in mTORC1 action, as S1261 phosphorylation promotes mTORC1-mediated substrate phosphorylation (e.g., p70 ribosomal protein S6 kinase 1 [S6K1] and eukaryotic initiation factor 4E binding protein 1) and cell growth to increased cell size. Moreover, Rheb-driven mTOR S2481 autophosphorylation and S6K1 phosphorylation require S1261 phosphorylation. These data provide the first evidence that site-specific mTOR phosphorylation regulates mTORC1 function and suggest a model whereby insulin-stimulated mTOR S1261 phosphorylation promotes mTORC1 autokinase activity, substrate phosphorylation, and cell growth.

AB - The mammalian target of rapamycin (mTOR) complex 1 (mTORC1) functions as a rapamycin-sensitive environmental sensor that promotes cellular biosynthetic processes in response to growth factors and nutrients. While diverse physiological stimuli modulate mTORC1 signaling, the direct biochemical mechanisms underlying mTORC1 regulation remain poorly defined. Indeed, while three mTOR phosphorylation sites have been reported, a functional role for site-specific mTOR phosphorylation has not been demonstrated. Here we identify a new site of mTOR phosphorylation (S1261) by tandem mass spectrometry and demonstrate that insulin-phosphatidylinositol 3-kinase signaling promotes mTOR S1261 phosphorylation in both mTORC1 and mTORC2. Here we focus on mTORC1 and show that TSC/Rheb signaling promotes mTOR S1261 phosphorylation in an amino acid-dependent, rapamycin-insensitive, and autophosphorylation-independent manner. Our data reveal a functional role for mTOR S1261 phosphorylation in mTORC1 action, as S1261 phosphorylation promotes mTORC1-mediated substrate phosphorylation (e.g., p70 ribosomal protein S6 kinase 1 [S6K1] and eukaryotic initiation factor 4E binding protein 1) and cell growth to increased cell size. Moreover, Rheb-driven mTOR S2481 autophosphorylation and S6K1 phosphorylation require S1261 phosphorylation. These data provide the first evidence that site-specific mTOR phosphorylation regulates mTORC1 function and suggest a model whereby insulin-stimulated mTOR S1261 phosphorylation promotes mTORC1 autokinase activity, substrate phosphorylation, and cell growth.

UR - http://www.scopus.com/inward/record.url?scp=67651210833&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=67651210833&partnerID=8YFLogxK

U2 - 10.1128/MCB.01665-08

DO - 10.1128/MCB.01665-08

M3 - Article

C2 - 19487463

AN - SCOPUS:67651210833

VL - 29

SP - 4308

EP - 4324

JO - Molecular and Cellular Biology

JF - Molecular and Cellular Biology

SN - 0270-7306

IS - 15

ER -