mTORC2 Protects the Heart from Ischemic Damage
Background—The mechanistic target of rapamycin (mTOR) is comprised of two structurally distinct multiprotein complexes, mTOR complexes 1 and 2 (mTORC1 and 2). Deregulation of mTOR signaling occurs during and contributes to the severity of myocardial damage from ischemic heart disease. However, the relative roles of mTORC1 versus mTORC2 in the pathogenesis of ischemic damage are unknown.
Methods and Results—Combined pharmacological and molecular approaches were used to alter the balance of mTORC1 and mTORC2 signaling in cultured cardiac myocytes and in mouse hearts subjected to conditions that mimic ischemic heart disease. The importance of mTOR signaling in cardiac protection was demonstrated by pharmacological inhibition of both mTORC1 and mTORC2 with Torin1, which led to increased cardiomyocyte apoptosis and tissue damage after myocardial infarction (MI). Predominant mTORC1 signaling mediated by suppression of mTORC2 with Rictor similarly increased cardiomyocyte apoptosis and tissue damage after MI. In comparison, preferentially shifting toward mTORC2 signaling by inhibition of mTORC1 with PRAS40 led to decreased cardiomyocyte apoptosis and tissue damage after MI.
Conclusions—These results suggest that selectively increasing mTORC2 while concurrently inhibting of mTORC1 signaling is a novel therapeutic approach for the treatment of ischemic heart disease.
- Received May 7, 2013.
- Revision received August 16, 2013.
- Accepted August 23, 2013.