Project description:Objective: To explore the protective effects of exercise-derived β-aminoisobutyric (BAIBA) on apoptosis and energy metabolism in rats with heart failure. Methods: A rat model of heart failure after myocardial infarction (MI) was started by ligating the left anterior descending branch of the coronary artery, the anterior descending branch of the rats in the SHAM group was only threaded and not ligated. Exercise intervention was given to rats with heart failure. The possible mechanisms by which exercise affected cardiac remodeling after MI were investigated using color ultrasound, HE, Masson, and TUNEL staining, and the detection of apoptosis-associated factors in cardiac tissue. High-throughput sequencing and mass spectrometry were used to measure the production of BAIBA and to explore its protective effects and molecular mechanisms. An in vitro model of apoptosis was created by the application of H2O2 to induce mitochondrial dysfunction. This was then transfected with miR-208b analogue and miR-208b-inhibitor. Apoptosis-related proteins were detected by Western blotting (WB), and ATP production was also assessed. After intervention with BAIBA and compound C, assessments were made of apoptosis, mitochondrial function, lipid uptake, utilization of related proteins, ATP changes, alterations in membrane potential (δψm), and changes in reactive oxygen species (ROS). Results: Compared with the control heart failure (HF) group, exercise improved the function of mitochondria, reversed the expression of apoptosis-related proteins, and increased ATP production. In both the normal and heart failure groups, exercise significantly increased the production of BAIBA. It was shown that BAIBA played a similar role to exercise in ameliorating heart failure. Transcriptome analysis confirmed that the expression of miR-208b was increased after BAIBA intervention, and transfection with miR-208b analogue increased both the expression of apoptosis-related proteins and energy metabolism in H9C2 cells induced by H2O2. Combined analysis of the transcriptome and metabolome identified AMPK as a target for BAIBA to improve metabolic stress. Cell experiments further confirmed that BAIBA increased AMPK phosphorylation and had a protective effect on downstream fatty acid uptake, oxidative efficiency, and mitochondrial function, which could be counteracted by the AMPK inhibitor compound C. Conclusion: Exercise-induced BAIBA can reduce the metabolic stress and apoptosis induced by mitochondrial dysfunction through the miR-208b/AMPK pathway.

Project description:Compelling evidence suggests that mitochondrial dysfunction contributes to the pathogenesis of heart failure, including defects in the substrate oxidation, and the electron transport chain (ETC) and oxidative phosphorylation (OXPHOS). However, whether such changes occur early in the development of heart failure, and are potentially involved in the pathologic events that lead to cardiac dysfunction is unknown. To address this question, we conducted transcriptomic/metabolomics profiling in hearts of mice with two progressive stages of pressure overload-induced cardiac hypetrophy: i) cardiac hypertrophy with preserved ventricular function achieved via transverse aortic constriction for 4 weeks (TAC) and ii) decompensated cardiac hypertrophy or heart failure (HF) caused by combining 4 wk TAC with a small apical myocardial infarction. Transcriptomic analyses revealed, as shown previously, downregulated expression of genes involved in mitochondrial fatty acid oxidation in both TAC and HF hearts compared to sham-operated control hearts. Surprisingly, however, there were very few changes in expression of genes involved in other mitochondrial energy transduction pathways, ETC, or OXPHOS. Metabolomic analyses demonstrated significant alterations in pathway metabolite levels in HF (but not in TAC), including elevations in acylcarnitines, a subset of amino acids, and the lactate/pyruvate ratio. In contrast, the majority of organic acids were lower than controls. This metabolite profile suggests “bottlenecks” in the carbon substrate input to the TCA cycle. This transcriptomic/metabolomic profile was markedly different from that of mice PGC-1a/b deficiency in which a global downregulation of genes involved in mitochondrial ETC and OXPHOS was noted. In addition, the transcriptomic/metabolomic signatures of HF differed markedly from that of the exercise-trained mouse heart. We conclude that in contrast to current dogma, alterations in mitochondrial metabolism that occur early in the development of heart failure reflect largely post-transcriptional mechanisms resulting in impedance to substrate flux into the TCA cycle, reflected by alterations in the metabolome. Microarray gene expression profiling was performed with bi-ventricle RNA isolated from (1) 3 month-old female C57Bl6/J mice with transverse aortic constriction (CH), vs sham-operated control (Sham-CH), (2) 3 month-old female C57Bl6/J mice with heart failure (HF), vs. sham-operated control (Sham-HF); (3) 2 month-old female C57Bl6/J mice with voluntary wheel training for 2 months (Run), vs. Sedentary control (Sed). Five biological replicates are included for each group.

Project description:Impaired myocardial contractile function is a hallmark of heart failure (HF) which may present under resting conditions and/or during physiological stress. Previous studies reported that high fat feeding in HF is associated with improved myocardial contractile function at baseline. Our goal was to determine whether myocardial function is compromised in response to physiological stress and to evaluate the global gene expression profile of rats fed high dietary fat following infarction. Male Wistar rats underwent ligation or sham surgery and were fed normal (10% kcal fat) (SHAM+NC, HF+NC) or high fat (60% kcal saturated fat) (SHAM+SAT, HF+SAT) for 8 weeks. Myocardial contractile function was assessed using a Millar pressure-volume (PV) conductance catheter at baseline, during inferior vena caval occlusions and dobutamine (DOB) stress. Steady state indices of systolic function, left ventricular (LV)+dP/dtmax, stroke work and maximal power were increased in HF+SAT vs HF+NC; HF+NC were reduced vs SHAM+NC. Preload-recruitable measures of contractility [end systolic PV relationship, maximal elastance, preload recruitable SW and peak+dP/dtmax to end diastolic volume] were decreased in HF+NC but not HF+SAT. β-adrenergic responsiveness (delta-LV+dP/dtmax and delta-cardiac output DOB 0-10 µg•kg-1•min-1) was reduced in HF, but high fat feeding did not further impact contractile reserve in HF. Contractile reserve was reduced by high fat in SHAM+SAT. Microarray gene expression analysis reveals the majority of significantly altered pathways identified to contain multiple gene targets correspond to cell signaling pathways and energy metabolism. These findings suggest that high saturated fat improves myocardial function at rest and during physiological stress in infarcted hearts, but may negatively impact contractile reserve under non-pathological conditions. Furthermore, high fat feeding-induced alterations in gene expression related to energy metabolism and specific signaling pathways reveal promising targets through which high saturated fat potentially mediates cardioprotection in heart failure/LV dysfunction. Comparison of gene expression in heart failure or sham surgery hearts exposed to saturated or normal diets. Male Wistar rats (300-350g) were maintained on a reverse light-dark cycle and all procedures were done 3-6 hours into the dark phase cycle to synchronize with the normal active state of the rodents. Rats were randomly assigned to receive either a sham-operation (SH) or coronary ligation to induce cardiac dysfunction (HF). Heart failure was induced by ligating the left main coronary artery. Following surgery, rats were immediately fed either a normal rodent chow (NC) or a high saturated fat chow (SAT) with 60% caloric content derived from fat (25% palmitic, 33% stearic, 33% oleic acid, Research Diets).

Project description:Compelling evidence suggests that mitochondrial dysfunction contributes to the pathogenesis of heart failure, including defects in the substrate oxidation, and the electron transport chain (ETC) and oxidative phosphorylation (OXPHOS). However, whether such changes occur early in the development of heart failure, and are potentially involved in the pathologic events that lead to cardiac dysfunction is unknown. To address this question, we conducted transcriptomic/metabolomics profiling in hearts of mice with two progressive stages of pressure overload-induced cardiac hypetrophy: i) cardiac hypertrophy with preserved ventricular function achieved via transverse aortic constriction for 4 weeks (TAC) and ii) decompensated cardiac hypertrophy or heart failure (HF) caused by combining 4 wk TAC with a small apical myocardial infarction. Transcriptomic analyses revealed, as shown previously, downregulated expression of genes involved in mitochondrial fatty acid oxidation in both TAC and HF hearts compared to sham-operated control hearts. Surprisingly, however, there were very few changes in expression of genes involved in other mitochondrial energy transduction pathways, ETC, or OXPHOS. Metabolomic analyses demonstrated significant alterations in pathway metabolite levels in HF (but not in TAC), including elevations in acylcarnitines, a subset of amino acids, and the lactate/pyruvate ratio. In contrast, the majority of organic acids were lower than controls. This metabolite profile suggests “bottlenecks” in the carbon substrate input to the TCA cycle. This transcriptomic/metabolomic profile was markedly different from that of mice PGC-1a/b deficiency in which a global downregulation of genes involved in mitochondrial ETC and OXPHOS was noted. In addition, the transcriptomic/metabolomic signatures of HF differed markedly from that of the exercise-trained mouse heart. We conclude that in contrast to current dogma, alterations in mitochondrial metabolism that occur early in the development of heart failure reflect largely post-transcriptional mechanisms resulting in impedance to substrate flux into the TCA cycle, reflected by alterations in the metabolome.

Project description:Purpose: Aerobic capacity is a strong predictor of cardiovascular mortality. To determine the relationship between inborn aerobic capacity and soleus gene expression we examined genome-wide gene expression in soleus muscle of rats artificially selected for high and low running capacity (HCR and LCR, respectively) over 16 generations. The artificial selection of LCR caused accumulation of risk factors of cardiovascular disease similar to the metabolic syndrome seen in man, whereas HCR had markedly better cardiac function. We also studied alterations in gene expression in response to exercise training in the two groups, since accumulating evidence indicates that exercise has profound beneficial effects on the metabolic syndrome. Methods:; Soleus gene expression of both sedentary and exercise trained HCR and LCR was characterized by microarray- and gene ontology analysis. Results: Although HCR and LCR had an inborn 347% difference in running capacity, only three genes were found differentially expressed in the soleus muscle between the two groups. Up-regulation of the mitochondrial enzyme leucyl-transferRNA synthetase (LARS2) was found in the sedentary LCR. Increased expression of LARS2 has been associated with a mitochondrial DNA mutation linked to maternally inherited diabetes and mitochondrial dysfunction. In line with our findings, a growing body of evidence suggests that LCR have compromised mitochondrial function. After exercise training, 58 genes were altered in the soleus muscle of HCR, in contrast to only one in the LCR group. This suggests that animals born with different levels of fitness respond different to the same type of exercise training. Adaptations to exercise in HCR seemed to be associated with increased lipid metabolism and fatty acid elongation in the mitochondria. Also, genes associated with the peroxisomes, seemed to be central in the adaptation to exercise. Conclusion: The results indicate that (i) LCR might have mitochondrial dysfunction, which may be a contributing factor of the low inborn aerobic capacity, (ii) animals born with different levels of fitness respond different to the same exercise program. Experiment Overall Design: There are 16 samples in this study.

Project description:Impaired myocardial contractile function is a hallmark of heart failure (HF) which may present under resting conditions and/or during physiological stress. Previous studies reported that high fat feeding in HF is associated with improved myocardial contractile function at baseline. Our goal was to determine whether myocardial function is compromised in response to physiological stress and to evaluate the global gene expression profile of rats fed high dietary fat following infarction. Male Wistar rats underwent ligation or sham surgery and were fed normal (10% kcal fat) (SHAM+NC, HF+NC) or high fat (60% kcal saturated fat) (SHAM+SAT, HF+SAT) for 8 weeks. Myocardial contractile function was assessed using a Millar pressure-volume (PV) conductance catheter at baseline, during inferior vena caval occlusions and dobutamine (DOB) stress. Steady state indices of systolic function, left ventricular (LV)+dP/dtmax, stroke work and maximal power were increased in HF+SAT vs HF+NC; HF+NC were reduced vs SHAM+NC. Preload-recruitable measures of contractility [end systolic PV relationship, maximal elastance, preload recruitable SW and peak+dP/dtmax to end diastolic volume] were decreased in HF+NC but not HF+SAT. β-adrenergic responsiveness (delta-LV+dP/dtmax and delta-cardiac output DOB 0-10 µg•kg-1•min-1) was reduced in HF, but high fat feeding did not further impact contractile reserve in HF. Contractile reserve was reduced by high fat in SHAM+SAT. Microarray gene expression analysis reveals the majority of significantly altered pathways identified to contain multiple gene targets correspond to cell signaling pathways and energy metabolism. These findings suggest that high saturated fat improves myocardial function at rest and during physiological stress in infarcted hearts, but may negatively impact contractile reserve under non-pathological conditions. Furthermore, high fat feeding-induced alterations in gene expression related to energy metabolism and specific signaling pathways reveal promising targets through which high saturated fat potentially mediates cardioprotection in heart failure/LV dysfunction.

Project description:Sudden cardiac death (SCD) associated with heart failure (HF) is a multifactorial problem requiring a systems level approach applied to suitable experimental animal models with features of the human disease. Here we examine key regulatory pathways underlying the transition from compensated hypertrophy (HYP) to decompensated HF and SCD by integrated analysis of the transcriptome, proteome and metabolome. In a guinea pig model of acquired long QT syndrome and HF/SCD, relative protein abundances from sham-operated, HYP and HF hearts were assessed using isobaric tags for relative and absolute quantification (iTRAQ), prior to liquid chromatography and tandem mass spectrometry (LC-MS/MS). Metabolites were quantified by LC-MS/MS or gas chromatography coupled to MS (GC-MS). Transcriptome profiles were obtained using DNA microarrays. The guinea pig HF proteome exhibited classic biosignatures of cardiac HYP, left ventricular dysfunction, fibrosis, cellular degeneration, inflammation and extravasation. Fatty acid metabolism, mitochondrial transcription/translation factors, antioxidant enzymes, and other mitochondrial processes, were downregulated in HF, but not HYP. Proteins upregulated in HF are consistent with extracellular matrix remodeling, cytoskeletal remodeling, and acute phase inflammation markers. Among metabolites, downregulation of acyl-carnitines was observed in HYP, while fatty acids accumulated in HF. Levels of the tricarboxylic acid (TCA) cycle metabolite, citrate, and the potent inhibitor, 2-methylcitrate, increased upon transition from HYP to HF. Correlation of the magnitude of transcript and protein changes in HF is weak (R2=0.23), indicating that targeting transcript/proteome may reveal inform post-transcriptional gene regulation in HF. Proteome/Metabolome integration suggests metabolic bottlenecks in fatty acyl-CoA processing by carnitine palmitoyl transferase (CPT1B) as well as TCA cycle inhibition. We present a model in which hallmarks of acute signaling in HF, including Ca2+ dysregulation and low cAMP levels, are coupled to mitochondrial metabolic and antioxidant defects, through a CREB/PGC1-alpha transcriptional axis.

Project description:Purpose: Aerobic capacity is a strong predictor of cardiovascular mortality. To determine the relationship between inborn aerobic capacity and soleus gene expression we examined genome-wide gene expression in soleus muscle of rats artificially selected for high and low running capacity (HCR and LCR, respectively) over 16 generations. The artificial selection of LCR caused accumulation of risk factors of cardiovascular disease similar to the metabolic syndrome seen in man, whereas HCR had markedly better cardiac function. We also studied alterations in gene expression in response to exercise training in the two groups, since accumulating evidence indicates that exercise has profound beneficial effects on the metabolic syndrome. Methods: Soleus gene expression of both sedentary and exercise trained HCR and LCR was characterized by microarray- and gene ontology analysis. Results: Although HCR and LCR had an inborn 347% difference in running capacity, only three genes were found differentially expressed in the soleus muscle between the two groups. Up-regulation of the mitochondrial enzyme leucyl-transferRNA synthetase (LARS2) was found in the sedentary LCR. Increased expression of LARS2 has been associated with a mitochondrial DNA mutation linked to maternally inherited diabetes and mitochondrial dysfunction. In line with our findings, a growing body of evidence suggests that LCR have compromised mitochondrial function. After exercise training, 58 genes were altered in the soleus muscle of HCR, in contrast to only one in the LCR group. This suggests that animals born with different levels of fitness respond different to the same type of exercise training. Adaptations to exercise in HCR seemed to be associated with increased lipid metabolism and fatty acid elongation in the mitochondria. Also, genes associated with the peroxisomes, seemed to be central in the adaptation to exercise. Conclusion: The results indicate that (i) LCR might have mitochondrial dysfunction, which may be a contributing factor of the low inborn aerobic capacity, (ii) animals born with different levels of fitness respond different to the same exercise program. Keywords: aerobic capacity, metabolic syndrome, soleus muscle, gene expression, metabolism

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Exercise-generated β-aminoisobutyric acid (BAIBA) reduces cardiomyocytes metabolic stress and apoptosis caused by mitochondrial dysfunction through the miR-208b/AMPK pathway

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