IRF4 in skeletal muscle regulates exercise capacity via PTG/glycogen pathway
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PROVIDER: PRJNA590273 | ENA |
REPOSITORIES: ENA
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Project description:Exercise-induced fatigue and exhaustion have been an interesting area for many physiologists.Muscle glycogen is critical forphysical performance. However, how glycogen depletion is manipulated during exercise is not very clear. Our aim here is to assess the impact of interferon regulatory factor 4 (IRF4) on skeletal muscle glycogen and subsequent regulation ofexercise capacity. Skeletal muscle-specific IRF4 knockout mice show normal body weight and insulin sensitivity, but better exercise capacity and increased glycogen content with unaltered triglyceride levels compared to control mice on chow diet. In contrast, mice overexpression of IRF4 display decreased exercise capacity and lower glycogen content. Mechanistically, IRF4 regulates glycogen-associated regulatory subunit protein targeting to glycogen (PTG) to manipulate glucose metabolism. Knockdown of PTG can reverse the effects imposed by the absence of IRF4in vivo. Our studies reveal a regulatory pathway including IRF4/PTG/glycogen synthesis that controlling exercise capacity.
2019-11-19 | GSE140633 | GEO
Project description:Skeletal muscle is not only a primary site for glucose uptake and storage, but also a reservoir for amino acids stored as protein. How the metabolism of these two fuels is coordinated in skeletal muscle is incompletely understood. Here, we demonstrate that interferon regulatory factor 4 (IRF4) integrate glucose and amino acids flux by regulating glycogen synthesis and branched-chain-amino acid (BCAA) metabolism in skeletal muscle. Mice with IRF4 specifically knocked out in skeletal muscle (MI4KO) showed elevated plasma BCAAs and skeletal muscle glycogen content, decreased adiposity and body weight, along with increased energy expenditure, remarkable improvements in glucose and insulin tolerance, and protection from diet-induced obesity (DIO). Loss of IRF4 caused downregulation of the mitochondrial branched-chain aminotransferase isozyme (BCATm) in myocytes, which encodes for the enzyme catalyzing the first step of BCAA metabolism. Lack of IRF4 also led to the upregulation of protein targeting to glycogen (PTG), which is associated with enhanced mitochondrial Complex II activity and mitochondria number. Additionally, overexpression of IRF4 in skeletal muscle caused obesity and reduced exercise capacity. Mechanistically, we found that IRF4 directly regulates both BCATm and PTG expression, and that overexpression of BCATm can partially reverse the effects of IRF4 deletion. These studies establish IRF4 as a novel driver of both glucose and BCAA metabolism in skeletal muscle.
2019-08-30 | GSE136623 | GEO
Project description:A single bout of exercise followed by intake of carbohydrates leads to glycogen supercompensation in the prior exercised muscle. The molecular mechanisms underlying this well-known phenomenon remain elusive. Here we report that a single bout of exercise induces marked activation of glycogen synthase (GS) and AMP-activated protein kinase (AMPK) for several days beyond normalized muscle glycogen content in man. Acute muscle specific deletion of AMPK activity in mouse muscle abrogated the ability for glycogen supercompensation, providing genetic evidence that AMPK serves as essential driver for glycogen supercompensation. Muscle proteomic analyses revealed elevated glucose uptake capacity in the prior exercised muscle while key proteins in fat oxidation and glycolysis largely remained unchanged. The temporal order of these sustained cellular alterations induced by a single bout of exercise provide a mechanism to offset the otherwise tight feedback inhibition of glycogen synthesis and glucose uptake by glycogen, ultimately leading to muscle glycogen supercompensation.
2018-08-30 | PXD009196 | Pride
Project description:Glycogen and lipid are major storage forms of energy that are tightly regulated by hormones and metabolic signals. Here, we evaluate the role of the glycogenic scaffolding protein PTG/R5 in energy homeostasis. We demonstrate that feeding mice a high-fat diet (HFD) increases hepatic glycogen, corresponding to increased PTG levels, increased activity of the mechanistic target of rapamycin complex 1 (mTORC1) and induced expression of sterol regulatory element binding protein 1c (SREBP1c). PTG promoter activity was increased by activation of mTORC1 and SREBP1, and PTG and glycogen levels were augmented in mice and cells in which mTORC1 is constitutively active. HFD-dependent increases in hepatic glycogen were prevented by deletion of the PTG gene in mice. Interestingly, PTG knockout mice fed HFD exhibited improved liver steatosis and decreased lipid levels in muscle, in coordination with decreased glycogen, suggesting possible crosstalk between glycogen and lipid stores in the overall control of energy metabolism. Together, these data suggest that transcriptional regulation of PTG by dietary and nutritional cues has profound effects on energy storage and metabolism.fi RNA-Seq analysis was used to characterize hepatic diet-associated gene expression changes between wild-type and PTG KO mice. Mice were maintained on a normal chow diet or a high-fat diet as indicated. 2-3 biological replicates per genotype/diet.
2014-06-13 | E-GEOD-45319 | biostudies-arrayexpress
Project description:Glycogen and lipid are major storage forms of energy that are tightly regulated by hormones and metabolic signals. Here, we evaluate the role of the glycogenic scaffolding protein PTG/R5 in energy homeostasis. We demonstrate that feeding mice a high-fat diet (HFD) increases hepatic glycogen, corresponding to increased PTG levels, increased activity of the mechanistic target of rapamycin complex 1 (mTORC1) and induced expression of sterol regulatory element binding protein 1c (SREBP1c). PTG promoter activity was increased by activation of mTORC1 and SREBP1, and PTG and glycogen levels were augmented in mice and cells in which mTORC1 is constitutively active. HFD-dependent increases in hepatic glycogen were prevented by deletion of the PTG gene in mice. Interestingly, PTG knockout mice fed HFD exhibited improved liver steatosis and decreased lipid levels in muscle, in coordination with decreased glycogen, suggesting possible crosstalk between glycogen and lipid stores in the overall control of energy metabolism. Together, these data suggest that transcriptional regulation of PTG by dietary and nutritional cues has profound effects on energy storage and metabolism.fi
2014-06-13 | GSE45319 | GEO
Project description:Background: Exercise mimetics is a proposed class of therapeutics that specifically mimics or enhances the therapeutic effects of exercise. Muscle glycogen and lactate extrusion are critical for physical performance. The mechanism by which glycogen and lactate metabolism are manipulated during exercise remains unclear. This study aimed to assess the effect of miR-92b on the upregulation of exercise training-induced physical performance. Methods: Adeno-associated virus (AAV)-mediated skeletal muscle miR-92b overexpression in C57BLKS/J mice, and global knockout of miR-92b mice were used to explore the function of miR-92b in glycogen and lactate metabolism in skeletal muscle. AAV-mediated UGP2 or MCT4 knockdown in WT or miR-92 knockout mice was used to confirm whether miR-92b regulates glycogen and lactate metabolism in skeletal muscle through UGP2 and MCT4. Body weight, muscle weight, grip strength, running time and distance to exhaustion, and muscle histology were assessed. The expression levels of muscle mass-related and functionrelated proteins were analysed by immunoblotting or immunostaining. Results: Global knockout of miR-92b resulted in normal body weight and insulin sensitivity, but higher glycogen content before exercise exhaustion (0.8538 ± 0.0417 vs 1.043 ± 0.040, **P=0.0087), lower lactate levels after exercise exhaustion (4.133 ± 0.2589 vs 3.207 ± 0.2511, *P=0.0279), and better exercise capacity (running distance to exhaustion, 3616 ± 86.71 vs 4231 ± 90.29, ***P=0.0006; running time to exhaustion, 186.8 ± 8.027 vs 220.8 ± 3.156, **P=0.0028), as compared to those observed in the control mice. Mice skeletal muscle overexpressing miR-92b (both miR-92b-3p and miR-92b-5p) displayed lower glycogen content before exercise exhaustion (0.6318 ± 0.0231 vs 0.535 ± 0.0194, **P=0.0094), and higher lactate accumulation after exercise exhaustion (4.5 ± 0.2394 vs 5.467 ± 0.1892, *P=0.01), and poorer exercise capacity (running distance to exhaustion, 4005 ± 81.65 vs 3228 ± 149.8, ***P＜0.0001; running time to exhaustion, 225.5 ± 7.689 vs 163 ± 6.476, **P=0.001). Mechanistic analysis revealed that miR-92b-3p targets UDP-glucose pyrophosphorylase 2 (UGP2) expression to inhibit glycogen synthesis, while miR-92b-5p represses lactate extrusion by directly target monocarboxylate transporter 4 (MCT4). Knockdown of UGP2 and MCT4 reversed the effects observed in the absence of miR-92b in vivo. Conclusions: This study revealed regulatory pathways, including miR-92b-3p/UGP2/glycogen synthesis and miR-92b-5p/MCT4/lactate extrusion, which could be targeted to control exercise capacity.
2023-10-01 | GSE242294 | GEO
Project description:Exercise-induced fatigue and exhaustion are interesting areas for many researchers. Muscle glycogen is critical for physical performance. However, how glycogen metabolism is manipulated during exercise is not very clear. The aim here is to assess the impact of interferon regulatory factor 4 (IRF4) on skeletal muscle glycogen and subsequent regulation of exercise capacity. Skeletal muscle-specific IRF4 knockout mice show normal body weight and insulin sensitivity, but better exercise capacity and increased glycogen content with unaltered triglyceride levels compared to control mice on chow diet. In contrast, mice overexpression of IRF4 displays decreased exercise capacity and lower glycogen content. Mechanistically, IRF4 regulates glycogen-associated regulatory subunit protein targeting to glycogen (PTG) to manipulate glucose metabolism in skeletal muscle. Knockdown of PTG can reverse the effects imposed by the absence of IRF4 in vivo. These studies reveal a regulatory pathway including IRF4/PTG/glycogen synthesis on controlling exercise capacity.
| S-EPMC7539189 | biostudies-literature
Project description:Metabolic regulation of BCAAs and glycogen via IRF4 in skeletal muscle
| PRJNA562888 | ENA
Project description:Epidemiological studies reveal a strong link between low aerobic capacity and metabolic and cardiovascular diseases. Two-way artificial selection of rats based on low and high intrinsic exercise capacity has produced two strains that also differ in risk for metabolic syndrome (Koch LG, Britton SL. Artificial selection for intrinsic aerobic endurance running capacity in rats. Physiol Genomics 5:45-52, 2001). Here we investigated skeletal muscle characteristics and genotype-phenotype relationships behind high and low inherited aerobic exercise capacity and the link between oxygen metabolism and metabolic disease risk factors in rats derived from generation 18. This population (n=24) of high capacity runners (HCR) and low capacity runners (LCR) differed by 615% in maximal treadmill running capacity. LCR were significantly significantly heavier and had increased blood glucose, serum insulin and triglyceride concentration. HCR had higher resting metabolic rate than LCR. Capillaries/mm2 and capillary-to-fiber ratio were significantly greater in HCR rats in soleus and gastrocnemius and capillary-to-fiber ratio in extensor digitorum longus (EDL) muscle. Subsarcolemmal mitochondrial area was 96% (p<0.01) and intermyofibrillar area was 32% (p<0.05) larger in HCR soleus. Microarray results showed that 126 genes were significantly up-regulated and 113 genes were down-regulated in HCR (p<0.05). Functional clustering and unbiased correlation analysis of muscle microarray data revealed that genes up-regulated in HCR were related to mitochondria, carboxylic acid and lipid metabolism, and oxidoreductase activity. In conclusion, our data show that aerobic capacity is strongly linked to the architecture of energy transfer and corroborate the importance of oxygen metabolism as the determinant of metabolic health and complex metabolic diseases such as metabolic syndrome and type 2 diabetes. Total RNA obtained from gastrocnemius muscle was compared between rat strains of low and high inherited aerobic exercise capacity.
2010-04-13 | E-GEOD-17190 | biostudies-arrayexpress
Project description:Epidemiological studies reveal a strong link between low aerobic capacity and metabolic and cardiovascular diseases. Two-way artificial selection of rats based on low and high intrinsic exercise capacity has produced two strains that also differ in risk for metabolic syndrome (Koch LG, Britton SL. Artificial selection for intrinsic aerobic endurance running capacity in rats. Physiol Genomics 5:45-52, 2001). Here we investigated skeletal muscle characteristics and genotype-phenotype relationships behind high and low inherited aerobic exercise capacity and the link between oxygen metabolism and metabolic disease risk factors in rats derived from generation 18. This population (n=24) of high capacity runners (HCR) and low capacity runners (LCR) differed by 615% in maximal treadmill running capacity. LCR were significantly significantly heavier and had increased blood glucose, serum insulin and triglyceride concentration. HCR had higher resting metabolic rate than LCR. Capillaries/mm2 and capillary-to-fiber ratio were significantly greater in HCR rats in soleus and gastrocnemius and capillary-to-fiber ratio in extensor digitorum longus (EDL) muscle. Subsarcolemmal mitochondrial area was 96% (p<0.01) and intermyofibrillar area was 32% (p<0.05) larger in HCR soleus. Microarray results showed that 126 genes were significantly up-regulated and 113 genes were down-regulated in HCR (p<0.05). Functional clustering and unbiased correlation analysis of muscle microarray data revealed that genes up-regulated in HCR were related to mitochondria, carboxylic acid and lipid metabolism, and oxidoreductase activity. In conclusion, our data show that aerobic capacity is strongly linked to the architecture of energy transfer and corroborate the importance of oxygen metabolism as the determinant of metabolic health and complex metabolic diseases such as metabolic syndrome and type 2 diabetes.
2010-04-01 | GSE17190 | GEO