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Altered proteome turnover and remodeling by short-term caloric restriction or rapamycin rejuvenate the aging heart.

ABSTRACT: Chronic caloric restriction (CR) and rapamycin inhibit the mechanistic target of rapamycin (mTOR) signaling, thereby regulating metabolism and suppressing protein synthesis. Caloric restriction or rapamycin extends murine lifespan and ameliorates many aging-associated disorders; however, the beneficial effects of shorter treatment on cardiac aging are not as well understood. Using a recently developed deuterated-leucine labeling method, we investigated the effect of short-term (10 weeks) CR or rapamycin on the proteomics turnover and remodeling of the aging mouse heart. Functionally, we observed that short-term CR and rapamycin both reversed the pre-existing age-dependent cardiac hypertrophy and diastolic dysfunction. There was no significant change in the cardiac global proteome (823 proteins) turnover with age, with a median half-life 9.1 days in the 5-month-old hearts and 8.8 days in the 27-month-old hearts. However, proteome half-lives of old hearts significantly increased after short-term CR (30%) or rapamycin (12%). This was accompanied by attenuation of age-dependent protein oxidative damage and ubiquitination. Quantitative proteomics and pathway analysis revealed an age-dependent decreased abundance of proteins involved in mitochondrial function, electron transport chain, citric acid cycle, and fatty acid metabolism as well as increased abundance of proteins involved in glycolysis and oxidative stress response. This age-dependent cardiac proteome remodeling was significantly reversed by short-term CR or rapamycin, demonstrating a concordance with the beneficial effect on cardiac physiology. The metabolic shift induced by rapamycin was confirmed by metabolomic analysis.

SUBMITTER: Dai DF

PROVIDER: S-EPMC4040127 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:OBJECTIVE: To understand the molecular pathways underlying the cardiac preconditioning effect of short-term caloric restriction (CR). BACKGROUND: Lifelong CR has been suggested to reduce the incidence of cardiovascular disease through a variety of mechanisms. However, prolonged adherence to a CR life-style is difficult. Here we show how short-term CR protects the mouse heart from ischemia. METHODS: Male 10-12 wk old C57bl/6 mice were randomly assigned to an ad libitum (AL) diet with free access to regular chow, or CR, receiving 30% less food over a period of 7 days (d), prior to myocardial infarction (MI) via permanent coronary ligation. Prior to MI (d8), the left ventricles (LV) of AL and CR mice were collected for Western blot, DNA and microRNA (miR) analyses. In separate groups, infarct size, cardiac hemodynamics and protein abundance of caspase 3 was measured at d2 post-MI. RESULTS: This short-term model of CR was associated with cardio-protection, as evidenced by decreased infarct size (18.5±2.4% vs. 26.6±1.7%, N=10/group; P=0.01). cDNA and miR profiles pre-MI (N=5/group) identified genes modulated by short-term CR to be associated with circadian clock, oxidative stress, immune function, apoptosis, metabolism, angiogenesis, cytoskeleton and extracellular matrix (ECM). Western blots pre-MI revealed CR-associated increases in phosphorylated Akt and GSK3ß, reduced levels of phosphorylated AMPK and mitochondrial related proteins PGC-1?, cytochrome C and cyclooxygenase (COX) IV, with no differences in the levels of phosphorylated eNOS or MAPK (ERK1/2; p38). CONCLUSIONS: Short-term CR for only 7d represents a preconditioning strategy that limits infarct size. It is associated with a unique gene and miR signature, including the activation of specific pro-survival kinases. These findings may have implications for therapeutic use of short-term CR. . Male 12 wk-old C57Bl/6 mice were obtained from Charles River (Montreal, PQ, Canada) and maintained for at least 2 weeks before experimentation. Animals were randomly assigned to AL, CR and Lira groups with no initial differences in body weights. AL group mice were allowed ad libitum diet. Lira group mice were injected with Liraglutide (Glucagon-like peptide-1 agonist) at a dose of 200 µg/Kg i.p., twice daily for 7 days which is a mild weight-loss inducing dose and had access to ad libitum food and water. CR group mice were put on a Caloric restriction diet (30% less than normal ad libitum caloric intake) for 7 days to induce weight loss comparable to Lira group mice. Mice for CR and AL were individually caged and their food intake was measured everyday between 10-11 am for 1 week to calculate the average daily food intake. CR mice were fed 30% less than the calculated mean daily AL food consumption. CR cages were inspected daily for any remaining food, and transferred to a new cage every day. For CR group, pre-weighed mouse chow pellets were placed in cages between 10-11 am every day. Body weights were recorded between 10-11 am before and after the 7 day study period. For pre-ischemic assessments, animals (n=5/group/assessment) were sacrificed on day-8 (pre-MI), hearts were immediately extracted, washed in sterile phosphate-buffered saline (PBS), with LV free walls dissected, snap frozen in liquid nitrogen and stored at -80o C.

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Altered proteome turnover and remodeling by short-term caloric restriction or rapamycin rejuvenate the aging heart.

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