Abstract 15454: Inhibition of Mechanistic Target of Rapamycin by Heterozygous Deletion of Raptor Ameliorates Pressure-overload Induced Heart Failure and the Associated Proteomics Remodeling
Background: We reported that inhibition of mechanistic target of rapamycin (mTOR) by short-term rapamycin or caloric restriction ameliorates age-dependent cardiac hypertrophy and diastolic dysfunction. Although inhibition of mTOR signaling is well known to regulate metabolism and suppress protein synthesis, the mechanisms of beneficial effect of mTOR inhibition in cardiac hypertrophy and failure are not fully understood.
Method: To investigate the mechanisms underlying beneficial effect of mTOR inhibition, we used the transverse aortic constriction (TAC)-induced heart failure model and examined the effect of heterozygous deletion of Raptor (Raptor het), a component of mTOR complex 1, and transgenic overexpression of cardiac specific wild type or mutant 4EBP1, one of the main downstream target of mTOR complex 1. Global proteomics analysis was performed using an improved label-free quantitative shotgun approach, followed by Ingenuity Pathway analysis.
Results: In wild-type mice with TAC-induced heart failure, global proteomics analysis revealed decreased abundance of proteins involved in mitochondrial function, electron transport chain, citric acid cycle and fatty acid metabolism and increased abundance of proteins involved in several signaling pathways (RhoA, actin, integrin) as well as oxidative stress response and protein ubiquitin pathways. Raptor het attenuate TAC induced heart failure, accompanied by better preservation of proteomics remodeling, especially the proteins involved in mitochondrial function, citric acid cycle and protein ubiquitination pathways. In contrast, either transgenic overexpression of wild type 4EBP1 or mutant 4EBP1 abolish the adaptive hypertrophy in response to TAC by suppressing protein translation, and thereby aggravate heart failure, in parallel with adverse remodeling of left ventricular proteomes. Neonatal cardiomyocyte experiments reveal that PGC1-α and Sirt3 are among the candidate signaling mechanisms linking the mTOR inhibition and mitochondrial metabolism.
Conclusion: mTOR inhibition by Raptor heterozygous deletion, but not overexpression of 4EBP1, ameliorates TAC-induced heart failure and associated with better preservation of mitochondrial proteome.
Author Disclosures: D. Dai: None.
- © 2014 by American Heart Association, Inc.