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Cardioprotective signature of short-term caloric restriction

ABSTRACT: 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-1α, 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. .

ORGANISM(S): Mus musculus

PROVIDER: GSE68646 | GEO | 2015/05/08

SECONDARY ACCESSION(S): PRJNA283288

REPOSITORIES: GEO

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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.

Project description:Aims. The goal of the study was to identify the possible transcriptional alterations responsible for the restoration of the second window preconditioning in the metabolic syndrome heart. Methods. LDLR-/-;ob/ob (DKO) and C57Bl6/J (WT) mice were injected with ACE-inhibitor, captopril (10 mg/kg/day) or NaCl 0.9% as controls. Preconditioning (HPC) was induced by five 6-min cycles at 6% oxygen interposed with 6 min at 21% oxygen. Non-preconditioned mice underwent a sham procedure without hypoxia. Transcriptome analysis (RNA-seq) from the whole heart RNA samples, differential gene expression with Cufdiff, pathway and network analysis with Ingenuity Pathway Analysis (IPA), qRT-PCR, and transcription factor motif enrichment analysis with i-cisTarget were performed. In separate groups, the infarct size was determined histologically after a 30-min occlusion of LAD, followed by 60-min reperfusion. Results. Preconditioning could not reduce infarct size in the untreated DKO mice (1+2%, p>.05). Preconditioning reduced infarct size to 28+2% in WT-HPC and to 23+1% in WTACE-I-HPC, both p<.05. In DKOACE-I hearts, preconditioning potential was partially restored with a reduction of infarct size by 16%. Preconditioning induced low number of differentially expressed genes (DEG) in DKO hearts (29 genes, p<.05) when compared WT and WTACE-I hearts (1634 and 2215 genes respectively, p<.05). In DKOACE-I, the number of DEG after preconditioning increased to 59, p<.05. In the three groups that could phenotypically be protected, preconditioning triggered shared pathways associated with the cell cycle quiescence, such as mTORC2 signaling, eIF2 signaling, regulation of eIF4 and p70S6K signaling, and actin cytoskeleton pathway signaling. The model-specific pathways and transcription factors differed between the groups. In the WT hearts, preconditioning enriched the pathways of mitochondrial biogenesis, oxidative phosphorylation, and anti-apoptotic signalling. In the WTACE-I hearts, preconditioning enriched the pathways of immune system signaling, metabolism, and cell cycle regulation. In the DKOACE-I hearts, pathways associated with negative inotropic effect and inhibition of myocyte growth were enriched after preconditioning. Conclusion. Our findings explain the molecular mechanism behind preconditioning in the healthy and the metabolic syndrome hearts. The phenotypically cardioprotective effect of HPC was absent in the metabolic syndrome hearts and was partially reinstated after ACE-I therapy. Transcriptional response to preconditioning differs between DKO and WT hearts and is model-specific with some degree of overlap.

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Cardioprotective signature of short-term caloric restriction

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