Abstract 13252: Pathological Hypertrophy Amelioration by Pras40-mediated Inhibition of Mtorc1
Background: mTOR complex 1 (mTORC1) necessary for cellular growth is regulated by intracellular signaling mediating inhibition of mTORC1 activation. Among mTORC1 regulatory binding partners, the role of Proline Rich AKT Substrate of 40kDa (PRAS40) in controlling mTORC1 activity and cellular growth in response to pathological and physiological stress in the heart has never been addressed.
Results: This report shows PRAS40 is regulated by AKT in cardiomyocytes and that AKT- driven phosphorylation relieves the inhibitory function of PRAS40. PRAS40 overexpression in vitro blocks mTORC1 in cardiomyocytes and decreases pathological growth. Cardiomyocyte specific overexpression in vivo blunts pathological remodeling after pressure overload, and preserves cardiac function. Inhibition of mTORC1 by PRAS40 preferentially promotes protective mTORC2 signaling in chronic diseased myocardium. In contrast, strong PRAS40 phosphorylation by AKT allows for physiological hypertrophy both in vitro and in vivo, whereas cardiomyocyte-specific overexpression of a PRAS40 mutant lacking capacity for AKT-phosphorylation inhibits physiological growth in vivo, demonstrating that AKT-mediated PRAS40 phosphorylation is necessary for induction of physiological hypertrophy.
Conclusions: Therefore, PRAS40 phosphorylation acts as a molecular switch allowing mTORC1 activation during physiological growth, opening up novel possibilities for therapeutic regulation of the mTORC1 complex to mitigate pathologic myocardial hypertrophy by PRAS40.
- © 2013 by American Heart Association, Inc.