title: 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 a central cell growth controller. TOR exists in two distinct complexes, termed TORC1 and TORC2. Mammalian TORC2 has recently been shown to possess kinase activity toward the C-terminal hydrophobic site of Akt/PKB. Here, we report that Sin1 is an essential component of TORC2 but not of TORC1, and functions similarly to Rictor, the defining member of TORC2, in complex formation and kinase activity. Knockdown of Sin1decreases Akt phosphorylation in both Drosophila and mammalian cells and diminishes Akt function in vivo. It also disrupts the interaction between Rictor and mTOR. Furthermore, Sin1 is required for TORC2 kinase activity in vitro. Disruption of the Rictor gene in mice results in embryonic lethality and ablates Akt phosphorylation. These data demonstrate that Sin1 together with Rictor are key components of mTORC2 and play an essential role in Akt phosphorylation and signaling.
authors.affiliation: Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Qian
authors.initials: Q
authors.lastname: Yang
authors.forename: Ken
authors.initials: K
authors.lastname: Inoki
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Ikenoue
authors.forename: Kun-Liang
authors.initials: KL
authors.lastname: Guan
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D017209:Apoptosis; D003599:Cytoskeleton / Q000378:metabolism; D004330:Drosophila / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D010750:Phosphoproteins / Q000502:physiology; D010766:Phosphorylation; D011494:Protein Kinases / Q000737:chemistry / Q000502:physiology*; D017434:Protein Structure, Tertiary; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases; D014157:Transcription Factors / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C500984:CRTC1 protein, human; C493245:CRTC2 protein, human; C493277:MAPKAP1 protein, human; D010750:Phosphoproteins; D014157:Transcription Factors; D011494:Protein Kinases; C546842:MTOR protein, human; C546843:mTOR protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases