ABSTRACT: Fish species display huge differences in physical activity ranging from lethargy to migration of thousands of miles, making them an interesting model for human exercise. Here, we show a remarkable plasticity of zebrafish in response to exercise and induction of PGC1α (encoded by PPARGC1A), a dominant regulator of mitochondrial biogenesis. Forced expression of human PPARGC1A induces mitochondrial biogenesis, an exercise-like gene expression signature, and physical fitness comparable to wild-type animals trained in counter-current swim tunnels. We quantify a stoichiometric induction of the electron transport chain (ETC) in response to exercise or PGC1α expression, identified by a proteomic SWATH-MS workflow. Exercise or PGC1α expression induce the re-organization of the ETC into respiratory supercomplexes, and we show that ndufa4/ndufa4l, previously assigned to complex I, associates to free and supramolecular complex IV in vivo. Thus, zebrafish is a useful and experimentally tractable vertebrate model to study exercise biology, including ETC expression and assembly.
Project description:Short-term intrauterine hyperglycaemia significantly reduced lean mass in male offspring at 8 weeks, resulting in decreased exercise endurance and metabolic disorders. Disrupted organization and function of the mitochondria in skeletal muscle were also observed among them. Foetal exposure to hyperglycaemia decreased phosphorylated CREB and reduced the transcription of Ppargc1a.
Project description:Various studies have shown that aerobic exercise can prevent or alleviate cancer-induced muscle wasting. To reproduce at least partially in vitro some molecular differences of aerobic muscle exercise that are independent from systemic inflammation or the hormonal milieu, we infected fully differentiated myotubes with adenoviruses expressing PGC1α, one of the main transcriptional coactivators involved in muscle adaptation to endurance exercise. We then compared the effect of PGC1α expression at 48h in myotubes infected with GFP, used as control.
Project description:Exercise attenuates the development of chronic non-communicable diseases (NCDs). Gene signaling pathway analysis offers an opportunity to discover if electrically induced muscle exercise regulates key pathways among people living with spinal cord injury (SCI). We examined short-term and long-term durations of electrically induced skeletal muscle exercise on complex gene signaling pathways, specific gene regulation, and epigenetic tagging of PGC1a, a major transcription factor in skeletal muscle of men with SCI. After short or long-term electrically induced exercise training, participants underwent biopsies of the trained and untrained muscles. RNA was hybridized to an exon microarray and analyzed using a gene set enrichment analysis. We discovered that long-term exercise training regulated the Reactome gene sets for Metabolism (38 gene sets), Cell Cycle (36 gene sets), Disease (27 gene sets), Gene Expression and Transcription (22 gene sets), Organelle Biogenesis (4 gene sets), Cellular Response to Stimuli (8 gene sets), Immune System (8 gene sets), Vesicle Mediated Transport (4 gene sets), and Transport of Small Molecules (3 gene sets). Specific gene expression included: Oxidative catabolism of glucose including PDHB (p<0.001), PDHX (p<0.001), MPC1 (p<0.009), and MPC2 (p<0.007); Oxidative phosphorylation genes including SDHA (p<0.006), SDHB (p<0.001), NDUFB1 (p<0.002), NDUFA2 (p<0.001); Transcription Genes including PGC1α (p<0.030) and PRKAB2 (p<0.011); Hypertrophy gene MSTN (p<0.001); and the Myokine generating FNDC5 gene (p<0.008). Long-term electrically induced exercise de-methylated the major transcription factor, PGC1a. Taken together, these findings support that long term electrically induced muscle activity regulates key pathways associated with muscle health and systemic metabolism.
Project description:Peroxisome proliferator-activated receptor (PPAR) γ coactivator 1α (PGC1α) is a coactivator of various nuclear receptors and other transcription factors that shows increased expression in skeletal muscle during exercise. In skeletal muscle, PGC1α is considered to be involved in contractile protein function, mitochondrial function, metabolic regulation, intracellular signaling, and transcriptional responses. Several isoforms of PGC1α mRNA have recently been identified. PGC1α-a is a full-length isoform of PGC1α that was the first to be isolated. PGC1α-b is another isoform of PGC1α, which is considered to be similar in function to PGC1α-a, differing by only 16 amino acids at the amino terminus. We have previously generated independent lines of transgenic mice that overexpress PGC1α-a or PGC1α-b in skeletal muscle. The microarray data shows that energy metabolism-related pathways such as the TCA cycle, branched-chain amino acid metabolism, purine nucleotide pathway, and malate–aspartate shuttle are activated in PGC1α transgenic mice compared with wild-type mice. For microarray analysis, RNA was isolated from the gastrocnemius skeletal muscle of wild-type control mice (12 weeks of age) as well as transgenic mice [PGC1α-a (E) (Miura et al., J. Biol. Chem. 278:31385-90, 2003), 12 weeks of age; PGC1α-b (02-1) (Miura et al., Endocrinology 149:4527-33, 2008), 14 weeks of age; and PGC1α-b (03-2) (Miura et al., Endocrinology 2008), 14 weeks of age]. Samples from wild-type and transgenic mice (N = 5 for each group) were pooled before use.
Project description:Rationale: Physical inactivity is a risk factor for insulin resistance. We examined the effect of nine days of bed rest on basal and insulin stimulated expression of genes potentially involved in insulin action by applying hypothesis-generating microarray in parallel with candidate gene real-time PCR approaches in 20 healthy, young men. Furthermore, we investigated whether bed rest affected DNA methylation in the promoter region of the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A) gene. Subjects were re-examined after four weeks of retraining. Findings: Bed rest induced insulin resistance and altered the expression of more than 4,500 genes. These changes were only partly normalized after four weeks of retraining. Pathway analyses revealed significant down-regulation of 34 pathways, predominantly those of genes associated with mitochondrial function including PPARGC1A. Despite induction of insulin resistance, bed rest resulted in a paradoxically increased response to acute insulin in the general expression of genes, particularly those involved in inflammation and endoplasmatic reticulum (ER) stress. Furthermore, bed rest changed gene expressions of several insulin resistance and diabetes candidate genes. We also observed a trend toward increased PPARGC1A DNA methylation after bed rest. Conclusions: Impaired expression of PPARGC1A and other genes involved in mitochondrial function as well as a paradoxically increased response to insulin of genes involved in inflammation and ER stress may contribute to the development of insulin resistance induced by bed rest. Lack of complete normalization of changes after four weeks of exercise retraining underscores the importance of maintaining a minimum of daily physical activity. 50 samples were collected (5 samples from 10 subjects) and included in this study. Ten technical repeats were also performed in this analysis
Project description:Mitochondrial adaptations play a central role in the beneficial effects of exercise, particularly in metabolically active tissues such as skeletal muscle. Despite this, the molecular regulators of mitochondrial adaptive responses have not yet been fully elucidated. The long non-coding RNA (lncRNA) taurine-upregulated gene 1 (TUG1) interacts with the master transcriptional regulator of mitochondrial biogenesis, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). In skeletal muscle of young healthy humans (n=14), we observed that TUG1 gene expression was elevated following an acute bout of continuous, moderate intensity cycling exercise and this positively correlated with PPARGC1A gene expression. Therefore, we hypothesised that TUG1 may modulate skeletal muscle mitochondrial responses to exercise. Knockdown (KD) of Tug1 in differentiating mouse myotubes resulted in altered mitochondrial morphology and impaired mitochondrial respiratory function, which was accompanied by greater myosin heavy chain slow isoform protein expression, despite lower Ppargc1a gene and MFN2 protein expression. Tug1 KD prevented the induction of Ppargc1a expression from a Ca2+ mediated stimulus (caffeine) yet the response to an AMPK agonist (AICAR ) was unaffected. RNA-sequencing revealed that Tug1 KD affected genes relating to mitochondrial Ca2+ transport and downstream targets of PGC-1α. Finally, in response to electrical pulse stimulation (EPS), an in vitro model of exercise in myotubes, there were ~300 genes whose upregulation in response to EPS was either blunted or augmented by Tug1 KD, including regulators of muscle differentiation and myogenesis. These data demonstrate that the lncRNA Tug1 is a novel regulator of skeletal muscle transcriptional responses to exercise and myogenesis.
Project description:Remyelination is a multistep regenerative process that results in the reformation of myelin sheaths around demyelinated axons and is a critical therapeutic target. Here we show that immediate access to a running wheel following toxin-induced demyelination in mice enhances oligodendrogenesis, myelin thickness, and the proportion of remyelinated axons. RNA-sequencing suggests broad activation of pro-remyelination pathways including phagocytosis by exercise and highlights peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1a) activation. Our study demonstrates that physical activity is an integrative means to enhance remyelination and details a multimodal mechanism including the pivotal PGC1a-dependent enhancement of myelin thickness.
Project description:Peroxisome proliferator-activated receptor (PPAR) γ coactivator 1α (PGC1α) is a coactivator of various nuclear receptors and other transcription factors that shows increased expression in skeletal muscle during exercise. In skeletal muscle, PGC1α is considered to be involved in contractile protein function, mitochondrial function, metabolic regulation, intracellular signaling, and transcriptional responses. Several isoforms of PGC1α mRNA have recently been identified. PGC1α-a is a full-length isoform of PGC1α that was the first to be isolated. PGC1α-b is another isoform of PGC1α, which is considered to be similar in function to PGC1α-a, differing by only 16 amino acids at the amino terminus. We have previously generated independent lines of transgenic mice that overexpress PGC1α-a or PGC1α-b in skeletal muscle. The microarray data shows that energy metabolism-related pathways such as the TCA cycle, branched-chain amino acid metabolism, purine nucleotide pathway, and malate–aspartate shuttle are activated in PGC1α transgenic mice compared with wild-type mice.
Project description:Rationale: Physical inactivity is a risk factor for insulin resistance. We examined the effect of nine days of bed rest on basal and insulin stimulated expression of genes potentially involved in insulin action by applying hypothesis-generating microarray in parallel with candidate gene real-time PCR approaches in 20 healthy, young men. Furthermore, we investigated whether bed rest affected DNA methylation in the promoter region of the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A) gene. Subjects were re-examined after four weeks of retraining. Findings: Bed rest induced insulin resistance and altered the expression of more than 4,500 genes. These changes were only partly normalized after four weeks of retraining. Pathway analyses revealed significant down-regulation of 34 pathways, predominantly those of genes associated with mitochondrial function including PPARGC1A. Despite induction of insulin resistance, bed rest resulted in a paradoxically increased response to acute insulin in the general expression of genes, particularly those involved in inflammation and endoplasmatic reticulum (ER) stress. Furthermore, bed rest changed gene expressions of several insulin resistance and diabetes candidate genes. We also observed a trend toward increased PPARGC1A DNA methylation after bed rest. Conclusions: Impaired expression of PPARGC1A and other genes involved in mitochondrial function as well as a paradoxically increased response to insulin of genes involved in inflammation and ER stress may contribute to the development of insulin resistance induced by bed rest. Lack of complete normalization of changes after four weeks of exercise retraining underscores the importance of maintaining a minimum of daily physical activity.