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Skeletal muscle mitochondrial dysfunction is secondary to T2DM

ABSTRACT: Skeletal muscle mitochondrial dysfunction is secondary to T2DM and can be improved by long-term regular exercise training Mitochondrial dysfunction has long been implicated to play a causative role in development of type 2 diabetes (T2DM). However, a growing number of recent studies provide data that mitochondrial dysfunction is a consequence of T2DM development. The aim of our study is to clarify in further detail the causal role of mitochondrial dysfunction in T2DM by a comprehensive ex vivo analysis of mitochondrial function combined with global gene expression analysis in muscle of pre-diabetic newly diagnosed untreated T2DM subjects and long-standing insulin treated T2DM subjects compared with age- and BMI-matched controls. In addition, we assessed the impact of long-term interval exercise training on physical activity performance, mitochondrial function and glycemic control in long-standing insulin-treated T2DM subjects. Ex vivo mitochondrial density, quality and functioning was comparable between pre-diabetic subjects and matched controls, however, gene expression analysis showed a switch from carbohydrate toward lipids as energy source in pre-diabetes subjects. In contrast, long-term insulin treated T2DM subjects had slightly decreased mitochondrial density and ex vivo function. Expression of Krebs cycle and OXPHOS related genes were decreased, indicating a decreased capacity to use lipids as an energy source. The insulin-treated T2DM subjects had a lower physical activity level than pre-diabetic and normoglycemic subjects. A 52 weeks exercise training of these subjects increased submaximal oxidative efficiency, increased in vivo PCr recovery rate, as well as mildly increased in vitro mitochondrial function. Gene expression of β-oxidation, Krebs cycle and OXPHOS-related genes was increased. Our data demonstrate that mitochondrial dysfunction is rather a consequence than a causative factor in T2DM development as it was only detected in overt diabetes and not in early diabetes. Regular exercise training stabilized exogenous insulin requirement and improved mitochondrial functioning, fatty acid oxidation and general physical work load capacity in long-standing insulin-treated T2DM subjects. As such, the present study shows for the first time that long-term exercise interventions are beneficial in this group of complex diabetes patient and may prevent further metabolic deterioration.

ORGANISM(S): Homo sapiens

PROVIDER: GSE19420 | GEO | 2010/11/29

SECONDARY ACCESSION(S): PRJNA120357

REPOSITORIES: GEO

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Project description:Skeletal muscle mitochondrial dysfunction is secondary to T2DM and can be improved by long-term regular exercise training Mitochondrial dysfunction has long been implicated to play a causative role in development of type 2 diabetes (T2DM). However, a growing number of recent studies provide data that mitochondrial dysfunction is a consequence of T2DM development. The aim of our study is to clarify in further detail the causal role of mitochondrial dysfunction in T2DM by a comprehensive ex vivo analysis of mitochondrial function combined with global gene expression analysis in muscle of pre-diabetic newly diagnosed untreated T2DM subjects and long-standing insulin treated T2DM subjects compared with age- and BMI-matched controls. In addition, we assessed the impact of long-term interval exercise training on physical activity performance, mitochondrial function and glycemic control in long-standing insulin-treated T2DM subjects. Ex vivo mitochondrial density, quality and functioning was comparable between pre-diabetic subjects and matched controls, however, gene expression analysis showed a switch from carbohydrate toward lipids as energy source in pre-diabetes subjects. In contrast, long-term insulin treated T2DM subjects had slightly decreased mitochondrial density and ex vivo function. Expression of Krebs cycle and OXPHOS related genes were decreased, indicating a decreased capacity to use lipids as an energy source. The insulin-treated T2DM subjects had a lower physical activity level than pre-diabetic and normoglycemic subjects. A 52 weeks exercise training of these subjects increased submaximal oxidative efficiency, increased in vivo PCr recovery rate, as well as mildly increased in vitro mitochondrial function. Gene expression of β-oxidation, Krebs cycle and OXPHOS-related genes was increased. Our data demonstrate that mitochondrial dysfunction is rather a consequence than a causative factor in T2DM development as it was only detected in overt diabetes and not in early diabetes. Regular exercise training stabilized exogenous insulin requirement and improved mitochondrial functioning, fatty acid oxidation and general physical work load capacity in long-standing insulin-treated T2DM subjects. As such, the present study shows for the first time that long-term exercise interventions are beneficial in this group of complex diabetes patient and may prevent further metabolic deterioration. Insulin-treated T2DM subjects before and after 52 weeks of exercise training (T2DM_0 and T2DM_52), normoglycemic controls (NGT) and pre-diabetes subjects (IGT) and were selected. RNA was extracted from skeletal muscle biopsies and hybridized on Affymetrix microarrays.

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.

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Skeletal muscle mitochondrial dysfunction is secondary to T2DM

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