Unknown,Transcriptomics,Genomics,Proteomics

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TGFÎ² contributes to impaired exercise response by suppression of mitochondrial key regulators in skeletal muscle

ABSTRACT: substantial number of people at risk to develop type 2 diabetes could not improve insulin sensitivity by physical training intervention. We studied the mechanisms of this impaired exercise response in 20 middle-aged individuals who performed a controlled eight weeks cycling and walking training at 80 % individual VO2max. Participants identified as non-responders in insulin sensitivity (based on Matsuda index) did not differ in pre-intervention parameters compared to high responders. The failure to increase insulin sensitivity after training correlates with impaired up-regulation of mitochondrial fuel oxidation genes in skeletal muscle, and with the suppression of the upstream regulators PGC1Î± and AMPKÎ±2. The muscle transcriptome of the non-responders is further characterized by an activation of TGFÎ² and TGFÎ² target genes, which is associated with increases in inflammatory and macrophage markers. TGFÎ²1 as inhibitor of mitochondrial regulators and insulin signaling is validated in human skeletal muscle cells. Activated TGFÎ²1 signaling down-regulates the abundance of PGC1Î±, AMPKÎ±2, mitochondrial transcription factor TFAM, and of mitochondrial enzymes. Thus, increased TGFÎ² activity in skeletal muscle can attenuate the improvement of mitochondrial fuel oxidation after training and contribute to the failure to increase insulin sensitivity. We performed gene expression microarray analysis on muscle biopsies from humans before and after an eight weeks endurance training intervention

ORGANISM(S): Homo sapiens

SUBMITTER: Johannes Beckers

PROVIDER: E-GEOD-72462 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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:The molecular pathways which are activated and contribute to physiological remodeling of skeletal muscle in response to endurance exercise have not been fully characterized. We previously reported that ~800 gene transcripts are regulated following 6 weeks of supervised endurance training in young sedentary males, referred to as the training responsive transcriptome (TRT). Here we utilized this database together with data on biological variation in muscle adaptation to aerobic endurance training in both humans and a novel out-bred rodent model to study the potential regulatory molecules that coordinate this complex network of genes. We identified three DNA sequences representing RUNX1, SOX9, and PAX3 transcription factor binding sites as over-represented in the TRT. In turn, miRNA profiling indicated that several miRNAs targeting RUNX1, SOX9 and PAX3 were down-regulated by endurance training. The TRT was then examined by contrasting subjects who demonstrated the least vs. the greatest improvement in aerobic capacity (low vs. high responders), and at least 100 of the 800 TRT genes were differentially regulated, thus suggesting regulation of these genes may be important for improving aerobic capacity. In high responders, pro-angiogenic and tissue developmental networks emerged as key candidates for coordinating tissue aerobic adaptation. Beyond RNA level validation there were several DNA variants that associated with VO(2)max trainability in the HERITAGE Family Study but these did not pass conservative Bonferroni adjustment. In addition, in a rat model selected across 10 generations for high aerobic training responsiveness, we found that both the TRT and a homologous subset of the human high responder genes were regulated to a greater degree in high responder rodent skeletal muscle. This analysis provides a comprehensive map of the transcriptomic features important for aerobic exercise-induced improvements in maximal oxygen consumption. This data is from skeletal muscle post 6 weeks of endurance exercise training.

Project description:The rates of obesity and sedentary lifestyle are on a dramatic incline, with associated detrimental health effects among women in particular. Although exercise prescriptions are useful for overcoming these problems, success can be hampered by differential responsiveness among individuals in cardiovascular fitness indices (i.e., improvements in strength, lipids, VO2max). Genetic factors appear to play an important role in determining this inter-individual variation in responsiveness. We performed microarray analyses on mRNA in whole blood from 60 sedentary women from a multi-ethnic cohort who underwent 12 weeks of exercise, to identify gene subsets that were differentially expressed between individuals who experienced the greatest and least improvements in fitness based upon a composite fitness score index. We identified 43 transcripts in 39 unique genes (FDR<10%; FC>1.5) whose expression increased the most in “high” versus “low” premenopausal female responders. Several (TIGD7, UQCRH, PSMA6, WDR12, TFB2M, USP15) have reported associations with fitness-related phenotypes. Bioinformatic analysis of the 39 genes identified 4 miRNAs whose expression has been linked to cardiovascular diseases (ANKRD22: miR-637, LRRFIP1: miR-132, PRKAR2B: miR-92a, RSAD2:miR-192). These 39 genes were enriched in 6 biological pathways, including the oxidative phosphorylation pathway (p=8.08 x 10-3). Two genes, LRRFIP1 and SNORD30, were also identified with lower expression in high responding postmenopausal women. In summary, we identified gene signatures based on mRNA analysis that define responsiveness to exercise in a largely minority-based female cohort. Importantly, this study validates several genes/pathways previously associated with exercise responsiveness and extends these findings with additional novel genes. We performed microarray analyses on mRNA in whole blood from 60 sedentary women from a multi-ethnic cohort who underwent 12 weeks of exercise, to identify gene subsets that were differentially expressed between individuals who experienced the greatest and least improvements in fitness based upon a composite fitness score index.

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TGFÎ² contributes to impaired exercise response by suppression of mitochondrial key regulators in skeletal muscle

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