Identification of Sin1 as an essential TORC2 component required for complex formation and kinase activity

Yang, Qian; Inoki, Ken; Ikenoue, Tsuneo; Guan, Kun Liang

doi:10.1101/gad.1461206

Cited by 447 publications

(451 citation statements)

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“…We report here the phosphorylation of Rictor at Thr1135, which is part of an AGC-kinase consensus sequence (RxRxxpS/T) and conserved among vertebrate Rictors. Other groups have reported that Rictor may be phosphorylated by observing its electrophoretic mobility and have suggested that these phosphorylations could be regulated (Sarbassov et al, 2004;Yang et al, 2006;Akcakanat et al, 2007). Although no effect of short-term rapamycin treatment has been reported on the electrophoretic mobility of Rictor, possibly reflecting the high molecular weight of Rictor, we show here using phospho-specific antibodies that amino acid and growth factor stimulation of cells induces Rictor phosphorylation at Thr1135 in a rapamycin-sensitive manner (Figure 2 and Supplementary Figure S1).…”

Section: Discussionmentioning

confidence: 99%

“…The ribosomal S6 kinases (S6Ks) and the eukaryotic initiation factor 4E-binding protein-1, both of which regulate protein synthesis, are the bestcharacterized mTORC1 substrates and play a critical role in the control of cell growth by mTORC1 (Inoki et al, 2005;Wullschleger et al, 2006;Ma and Blenis, 2009). The second complex, mTORC2, also contains mTOR, mLST8/GbL and DEPTOR associated with Rictor (the rapamycin-insensitive companion of mTOR), Sin1 (stress-activated, protein kinase-interacting protein-1) and Protor (protein associated with Rictor) (Jacinto et al, 2004(Jacinto et al, , 2006Sarbassov et al, 2004;Frias et al, 2006;Yang et al, 2006;Pearce et al, 2007;Peterson et al, 2009). mTOR assembled into mTORC2 modulates cell proliferation and survival in response to growth factors by promoting the phosphorylation and activation of Akt/PKB, PKC (protein kinase-C) and SGK1 (serum-glucocorticoid-induced protein kinase-1) (Sarbassov et al, 2004(Sarbassov et al, , 2005Guertin et al, 2006;Facchinetti et al, 2008;Garcia-Martinez and Alessi, 2008;Ikenoue et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Rictor is a novel target of p70 S6 kinase-1

et al. 2009

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The rapamycin-insensitive companion of mammalian target of rapamycin (mTOR) (Rictor) is a key member of mTOR complex-2 (mTORC2), which phosphorylates the AGC kinases Akt/PKB, PKC and SGK1 at a C-terminal hydrophobic motif. We identified several novel sites on Rictor that are phosphorylated, including Thr1135, which is conserved across all vertebrates. Phosphorylation of this site on Rictor is stimulated by amino acids and growth factors through a rapamycin-sensitive signaling cascade. We demonstrate here that Rictor is a direct target of the ribosomal protein S6 kinase-1 (S6K1). Rictor phosphorylation at Thr1135 does not lead to major changes in mTORC2-kinase activity. However, phosphorylation of this site turns over rapidly and mediates 14-3-3 binding to Rictor and mTORC2, providing possibility for altered interactions of the complex. These findings reveal an unexpected signaling input into mTORC2, which is regulated by amino acids, growth factors and rapamycin.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rictor is a novel target of p70 S6 kinase-1

et al. 2009

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“…One AKTsubstrate important in cell survival that appears to require mTORC2 activity is the FoxO1/ 3a transcription factors (Guertin et al 2006Jacinto et al 2006;Yang et al 2006). For example, FoxO1 (T24) and FoxO3a (T32) phosphorylation is decreased upon mTORC2 inactivation in both knockdown and genetic knockout studies.…”

Section: Mtorc2-dependent Cell Survival Pathwaysmentioning

confidence: 99%

“…The reason for this discrepancy remains unclear but may reflect a difference between acute knockdown and chronic knockout experiments, or the existence of a compensatory mechanism. Although phosphorylation at both T308 and S473 is required for maximal AKT activity in vitro, it appears that T308 phosphorylation alone empowers AKT with enough activity to phosphorylate many of its substrates in cultured cells or in tissues (Alessi et al 1996;Guertin et al 2006;Jacinto et al 2006;Yang et al 2006;Bentzinger et al 2008;Kumar et al 2008Kumar et al , 2010Cybulski et al 2009;Gu et al 2011).…”

Section: Mtorc2-dependent Cell Survival Pathwaysmentioning

confidence: 99%

mTOR-Dependent Cell Survival Mechanisms

Hung

García-Haro

Sparks

et al. 2012

Cold Spring Harbor Perspectives in Biology

157

134

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The mechanistic target of rapamycin (mTOR) kinase is a conserved regulator of cell growth, proliferation, and survival. In cells, mTOR is the catalytic subunit of two complexes called mTORC1 and mTORC2, which have distinct upstream regulatory signals and downstream substrates. mTORC1 directly senses cellular nutrient availability while indirectly sensing circulating nutrients through growth factor signaling pathways. Cellular stresses that restrict growth also impinge on mTORC1 activity. mTORC2 is less well understood and appears only to sense growth factors. As an integrator of diverse growth regulatory signals, mTOR evolved to be a central signaling hub for controlling cellular metabolism and energy homoeostasis, and defects in mTOR signaling are important in the pathologies of cancer, diabetes, and aging. Here we discuss mechanisms by which each mTOR complex might regulate cell survival in response to metabolic and other stresses.

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“…The two TOR complexes were initially identified in yeast and subsequently were also characterized in Drosophila and mammalian cells. TORC1 contains mTOR, mLST8, PRAS40, and Raptor, whereas TORC2 contains mTOR, mLST8, Rictor, and Sin1 (5)(6)(7)(8)(9)(10)(11)(12). TORC1 is responsible for phosphorylation of Thr 389 of S6K1 (ribosomal protein S6 kinase) and 4EBP1 (eukaryote initiation factor 4E-binding protein), two important regulators in protein synthesis (1).…”

mentioning

confidence: 99%

Bnip3 Mediates the Hypoxia-induced Inhibition on Mammalian Target of Rapamycin by Interacting with Rheb

Wang²,

Kim

et al. 2007

Journal of Biological Chemistry

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230

194

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The mammalian target of rapamycin (mTOR) is a central controller of cell growth, and it regulates translation, cell size, cell viability, and cell morphology. mTOR integrates a wide range of extracellular and intracellular signals, including growth factors, nutrients, energy levels, and stress conditions. Rheb, a Ras-related small GTPase, is a key upstream activator of mTOR. In this study, we found that Bnip3, a hypoxia-inducible Bcl-2 homology 3 domain-containing protein, directly binds Rheb and inhibits the mTOR pathway. Bnip3 decreases Rheb GTP levels in a manner depending on the binding to Rheb and the presence of the N-terminal domain. Both knockdown and overexpression experiments show that Bnip3 plays an important role in mTOR inactivation in response to hypoxia. Moreover, Bnip3 inhibits cell growth in vivo by suppressing the mTOR pathway. These observations demonstrate that Bnip3 mediates the inhibition of the mTOR pathway in response to hypoxia.Target of rapamycin (TOR), 2 is an evolutionarily conserved serine/threonine kinase that plays a central role in cell growth (1-3). TOR regulates many processes, including protein translation, ribosome biogenesis, autophagy, and metabolism. TOR functions to integrate a wide range of extracellular and intracellular signals to produce a concerted cellular response, such as to stimulate cell growth. For example, mammalian target of rapamycin (mTOR) is activated by growth factor and nutrient availability. In contrast, mTOR is inhibited by cellular energy starvation and various stress conditions, including osmotic stress and hypoxia. These observations established a fundamental importance of mTOR in signal integration in regulation of cell growth.Recent studies have demonstrated that TOR exists in two functionally distinct protein complexes, termed TOR complex 1 (TORC1) and TOR complex 2 (TORC2) (3, 4). The two TOR complexes were initially identified in yeast and subsequently were also characterized in Drosophila and mammalian cells. TORC1 contains mTOR, mLST8, PRAS40, and Raptor, whereas TORC2 contains mTOR, mLST8, Rictor, and Sin1 (5-12). TORC1 is responsible for phosphorylation of Thr 389 of S6K1 (ribosomal protein S6 kinase) and 4EBP1 (eukaryote initiation factor 4E-binding protein), two important regulators in protein synthesis (1). In contrast, TORC2 has different substrates and is responsible for phosphorylation of the hydrophobic sites in both AKT and PKC (9, 13). Interestingly, TORC1 but not TORC2 is inhibited by rapamycin (6,8,9). These observations clearly demonstrate that the two TOR complexes have different physiological functions in vivo.Much progress has been made regarding the mechanisms of TORC1 regulation. Tuberous sclerosis complex (TSC) is a genetic disease characterized by benign hamartomas in various tissues (14). Mutations in either the TSC1 or TSC2 tumor suppressor gene are responsible for TSC development. TORC1 is highly activated in TSC tumors or cells with mutation of either TSC1 or TSC2. Both genetic and biochemical data have demonstrated th...

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Identification of Sin1 as an essential TORC2 component required for complex formation and kinase activity

Abstract: Target of rapamycin (TOR) is an evolutionally conserved protein kinase in eukaryotes and[Keywords: Sin1; TORC; TSC; Rictor; Akt; mTOR] Supplemental material is available at http://www.genesdev.org.

Cited by 447 publications

References 42 publications

Rictor is a novel target of p70 S6 kinase-1

Rictor is a novel target of p70 S6 kinase-1

mTOR-Dependent Cell Survival Mechanisms

Bnip3 Mediates the Hypoxia-induced Inhibition on Mammalian Target of Rapamycin by Interacting with Rheb

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