PMID- 23673367 OWN - NLM STAT- MEDLINE DCOM- 20140127 LR - 20240322 IS - 1873-3913 (Electronic) IS - 0898-6568 (Print) IS - 0898-6568 (Linking) VI - 25 IP - 9 DP - 2013 Sep TI - mTOR complex 2 mediates Akt phosphorylation that requires PKCepsilon in adult cardiac muscle cells. PG - 1904-12 LID - S0898-6568(13)00125-3 [pii] LID - 10.1016/j.cellsig.2013.05.001 [doi] AB - Our earlier work showed that mammalian target of rapamycin (mTOR) is essential to the development of various hypertrophic responses, including cardiomyocyte survival. mTOR forms two independent complexes, mTORC1 and mTORC2, by associating with common and distinct cellular proteins. Both complexes are sensitive to a pharmacological inhibitor, torin1, although only mTORC1 is inhibited by rapamycin. Since mTORC2 is known to mediate the activation of a prosurvival kinase, Akt, we analyzed whether mTORC2 directly mediates Akt activation or whether it requires the participation of another prosurvival kinase, PKCepsilon (epsilon isoform of protein kinase-C). Our studies reveal that treatment of adult feline cardiomyocytes in vitro with insulin results in Akt phosphorylation at S473 for its activation which could be augmented with rapamycin but blocked by torin1. Silencing the expression of Rictor (rapamycin-insensitive companion of mTOR), an mTORC2 component, with a sh-RNA in cardiomyocytes lowers both insulin-stimulated Akt and PKCepsilon phosphorylation. Furthermore, phosphorylation of PKCepsilon and Akt at the critical S729 and S473 sites respectively was blocked by torin1 or Rictor knockdown but not by rapamycin, indicating that the phosphorylation at these specific sites occurs downstream of mTORC2. Additionally, expression of DN-PKCepsilon significantly lowered the insulin-stimulated Akt S473 phosphorylation, indicating an upstream role for PKCepsilon in the Akt activation. Biochemical analyses also revealed that PKCepsilon was part of Rictor but not Raptor (a binding partner and component of mTORC1). Together, these studies demonstrate that mTORC2 mediates prosurvival signaling in adult cardiomyocytes where PKCepsilon functions downstream of mTORC2 leading to Akt activation. CI - Copyright (c) 2013 Elsevier Inc. All rights reserved. FAU - Moschella, Phillip C AU - Moschella PC AD - Cardiology Division of the Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, SC 29425-2221, United States. FAU - McKillop, John AU - McKillop J FAU - Pleasant, Dorea L AU - Pleasant DL FAU - Harston, Rebecca K AU - Harston RK FAU - Balasubramanian, Sundaravadivel AU - Balasubramanian S FAU - Kuppuswamy, Dhandapani AU - Kuppuswamy D LA - eng GR - T32HL07260/HL/NHLBI NIH HHS/United States GR - R01 HL092124/HL/NHLBI NIH HHS/United States GR - R25 GM072643/GM/NIGMS NIH HHS/United States GR - RHL092124A/PHS HHS/United States GR - T32 HL007260/HL/NHLBI NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural DEP - 20130511 PL - England TA - Cell Signal JT - Cellular signalling JID - 8904683 RN - 0 (Multiprotein Complexes) RN - EC 2.7.11.1 (Mechanistic Target of Rapamycin Complex 2) RN - EC 2.7.11.1 (Proto-Oncogene Proteins c-akt) RN - EC 2.7.11.1 (TOR Serine-Threonine Kinases) RN - EC 2.7.11.13 (Protein Kinase C-epsilon) SB - IM MH - Animals MH - Cats MH - Cells, Cultured MH - Mechanistic Target of Rapamycin Complex 2 MH - Multiprotein Complexes/*metabolism MH - Myocytes, Cardiac/*metabolism MH - Phosphorylation MH - Protein Kinase C-epsilon/*metabolism MH - Proto-Oncogene Proteins c-akt/*metabolism MH - TOR Serine-Threonine Kinases/*metabolism PMC - PMC3704180 MID - NIHMS479092 EDAT- 2013/05/16 06:00 MHDA- 2014/01/28 06:00 PMCR- 2014/09/01 CRDT- 2013/05/16 06:00 PHST- 2013/03/12 00:00 [received] PHST- 2013/05/06 00:00 [accepted] PHST- 2013/05/16 06:00 [entrez] PHST- 2013/05/16 06:00 [pubmed] PHST- 2014/01/28 06:00 [medline] PHST- 2014/09/01 00:00 [pmc-release] AID - S0898-6568(13)00125-3 [pii] AID - 10.1016/j.cellsig.2013.05.001 [doi] PST - ppublish SO - Cell Signal. 2013 Sep;25(9):1904-12. doi: 10.1016/j.cellsig.2013.05.001. Epub 2013 May 11.