Project description:This experiment was conducted to identify target genes of the peroxisome proliferator-activated receptor beta (PPARb) in skeletal muscle of transgenic mice that overexpressed PPARb. The following abstract from the submitted manuscript describes the major findings of this work. The Nuclear Receptor Transcription Factor PPARbeta/delta Programs Muscle Glucose Metabolism. Zhenji Gan, Eileen Burkart-Hartman, Dong-Ho Han, Brian Finck, Teresa C. Leone, John Holloszy, and Daniel P. Kelly. To identify new gene regulatory pathways controlling skeletal muscle energy metabolism, comparative studies were conducted on muscle-specific transgenic mouse lines expressing the nuclear receptors, PPARalpha (MCK-PPARalpha) or PPARbeta/delta (MCK-PPARbeta/delta). MCK-PPARbeta/delta mice are known to have enhanced exercise performance whereas MCK-PPARalpha mice perform at low levels. Transcriptional profiling revealed that the lactate dehydrogenase (Ldh)b/Ldha gene expression ratio is increased in MCK-PPARbeta/delta muscle, an isoenzyme shift that diverts pyruvate into the mitochondrion for the final steps of glucose oxidation. PPARbeta/delta gain- and loss-of-function studies in skeletal myotubes demonstrated that PPARbeta/delta, but not PPARalpha, interacts with the exercise inducible kinase, AMP-activated protein kinase (AMPK), to synergistically activate Ldhb gene transcription by cooperating with myocyte enhancer factor 2A (MEF2A), in a PPARbeta/delta ligand-independent manner. MCK-PPARbeta/delta muscle was shown to have high glycogen stores, increased levels of GLUT4, and augmented capacity for mitochondrial pyruvate oxidation suggesting a broad reprogramming of glucose utilization pathways. Lastly, exercise studies demonstrated that MCK-PPARbeta/delta mice had lower circulating levels of lactate compared to non-transgenic controls, while exhibiting supranormal performance on a high intensity exercise regimen. These results identify a transcriptional regulatory mechanism that increases capacity for muscle glucose utilization in a pattern that resembles the effects of exercise training. Keywords: muscle, exercise, nuclear receptors, glucose metabolism, gene regulation RNA from two wild-type (non-transgenic (NTG)) and two PPARbeta overexpressing (MCK-PPARb) mice was analyzed. Two replicates of each are provided.
Project description:This experiment was conducted to identify target genes of the peroxisome proliferator-activated receptor beta (PPARb) in skeletal muscle of transgenic mice that overexpressed PPARb. The following abstract from the submitted manuscript describes the major findings of this work. The Nuclear Receptor Transcription Factor PPARbeta/delta Programs Muscle Glucose Metabolism. Zhenji Gan, Eileen Burkart-Hartman, Dong-Ho Han, Brian Finck, Teresa C. Leone, John Holloszy, and Daniel P. Kelly. To identify new gene regulatory pathways controlling skeletal muscle energy metabolism, comparative studies were conducted on muscle-specific transgenic mouse lines expressing the nuclear receptors, PPARalpha (MCK-PPARalpha) or PPARbeta/delta (MCK-PPARbeta/delta). MCK-PPARbeta/delta mice are known to have enhanced exercise performance whereas MCK-PPARalpha mice perform at low levels. Transcriptional profiling revealed that the lactate dehydrogenase (Ldh)b/Ldha gene expression ratio is increased in MCK-PPARbeta/delta muscle, an isoenzyme shift that diverts pyruvate into the mitochondrion for the final steps of glucose oxidation. PPARbeta/delta gain- and loss-of-function studies in skeletal myotubes demonstrated that PPARbeta/delta, but not PPARalpha, interacts with the exercise inducible kinase, AMP-activated protein kinase (AMPK), to synergistically activate Ldhb gene transcription by cooperating with myocyte enhancer factor 2A (MEF2A), in a PPARbeta/delta ligand-independent manner. MCK-PPARbeta/delta muscle was shown to have high glycogen stores, increased levels of GLUT4, and augmented capacity for mitochondrial pyruvate oxidation suggesting a broad reprogramming of glucose utilization pathways. Lastly, exercise studies demonstrated that MCK-PPARbeta/delta mice had lower circulating levels of lactate compared to non-transgenic controls, while exhibiting supranormal performance on a high intensity exercise regimen. These results identify a transcriptional regulatory mechanism that increases capacity for muscle glucose utilization in a pattern that resembles the effects of exercise training. Keywords: muscle, exercise, nuclear receptors, glucose metabolism, gene regulation
Project description:This experiment was conducted to identify target microRNAs of the peroxisome proliferator-activated receptor (PPAR) in skeletal muscle of transgenic mice that overexpressed PPARalpha or PPARbeta. We have recently demonstrated that skeletal muscle-specific PPARb transgenic (MCK-PPARb) mice exhibit increased exercise endurance, whereas MCK-PPARa mice have reduced exercise performance. Accordingly, we sought to determine whether PPARb and PPARa drive distinct programs involved in muscle fiber type determination. Myosin heavy chain (MHC) immunohistochemical staining of soleus muscle revealed a marked increase in type 1 fibers in the MCK-PPARb muscle compared to non-transgenic (NTG) littermates but a profound reduction in MCK-PPARa muscle. miRNA profiling revealed that levels of miR-208b and miR-499 were increased in MCK-PPARb muscle but reduced in MCK-PPARa muscle. miR-208b and miR-499, which are embedded in the Myh7 and Myh7b genes, respectively, have been shown previously to regulate slow-twitch muscle genes. Lastly, combined inhibition of miR-208b and miR-499 abolished the enhancing effects of PPARb on MHC1 expression in skeletal myotubes, while forced expression of miR-499 in MCK-PPARa muscle completely reversed the type 1 fiber program and exercise capacity. Taken together, these findings demonstrate that miR-208b and miR-499 are necessary to mediate the effects of PPARb and PPARa on muscle fiber type determination. Comparison of microRNA expression from soleus muscles isolated from wild-type (non-transgenic (NTG)) and PPARalpha-overexpressing (MCK-PPARa) mice, and comparison of microRNA expression from soleus muscles isolated from wild-type (NTG) and PPARbeta-overexpressing (MCK-PPARb) mice. Three replicates of each are analyzed.
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from seven Mus musculus tissues (Heart, Brain, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:This experiment was conducted to identify target genes of the peroxisome proliferator-activated receptor alpha (PPARa) in skeletal muscle of transgenic mice that overexpressed PPARa. The following abstract from the published manuscript describes the major findings of this work. A potential link between muscle peroxisome proliferator- activated receptor-alpha signaling and obesity-related diabetes.Finck BN, Bernal-Mizrachi C, Han DH, Coleman T, Sambandam N, LaRiviere LL, Holloszy JO, Semenkovich CF, Kelly DP. The role of the peroxisome proliferator-activated receptor-alpha (PPARalpha) in the development of insulin-resistant diabetes was evaluated using gain- and loss-of-function approaches. Transgenic mice overexpressing PPARalpha in muscle (MCK-PPARalpha mice) developed glucose intolerance despite being protected from diet-induced obesity. Conversely, PPARalpha null mice were protected from diet-induced insulin resistance in the context of obesity. In skeletal muscle, MCK-PPARalpha mice exhibited increased fatty acid oxidation rates, diminished AMP-activated protein kinase activity, and reduced insulin-stimulated glucose uptake without alterations in the phosphorylation status of key insulin-signaling proteins. These effects on muscle glucose uptake involved transcriptional repression of the GLUT4 gene. Pharmacologic inhibition of fatty acid oxidation or mitochondrial respiratory coupling prevented the effects of PPARalpha on GLUT4 expression and glucose homeostasis. These results identify PPARalpha-driven alterations in muscle fatty acid oxidation and energetics as a potential link between obesity and the development of glucose intolerance and insulin resistance. Experiment Overall Design: RNA from two wild-type (non-transgenic (NTG)) and two PPARalpha overexpressing (MCK-PPARa) mice was analyzed. Two replicates of each are provided.