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: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 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.
Project description:We analyzed the gene expression changes that result from mitochondria overloaded by unfolded proteins in skeletal muscles. Mitochondrial-retained mutant ornithine transcarbamylase (ΔOTC) is a known protein degraded by LONP1 and an established model for studying mitochondrial proteostasis imbalance. We generated transgenic mice overexpressing ΔOTC specifically in skeletal muscle using the muscle creatine kinase promoter (MCK-ΔOTC). Transcriptome analysis was performed by whole-genome gene expression profiling experiments in muscles from the MCK-ΔOTC mice and NTG littermate controls. The comparative mRNA profiling strategy revealed extensive genomic reprogramming in MCK-ΔOTC muscles, with 1051 genes up- and 519 genes down-regulated (1.5-fold change and p<0.05), respectively. GO analysis of the regulated genes in MCK-ΔOTC muscles revealed significant enrichment in unfolded protein response as well as RNA processing process. These data suggest that mitochondria overloaded by ΔOTC unfolded proteins induce extensive genomic reprogramming in skeletal muscle
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:Congenital obstructive nephropathy (CON) is the leading cause of chronic kidney disease (CKD) in children. CON is a complex disease process involving pathological changes in kidney development and function that occur as a result of obstructed antegrade urine flow beginning in utero. The megabladder (mgb-/-) mouse is an animal model of CON that develops kidney disease secondary to a bladder-specific defect in smooth muscle development. Expression levels of specific microRNAs were compared by microarray analysis on the Agilent platform and by quantitative PCR (qPCR) of kidney samples from wild type and mgb-/- mice.
Project description:Gprc6a|Mck-/- (Gcrp6a skeletal muscle specific knockout)(n=4) are compared to Gprc6afl/fl (WT) mice (n=4). Gprc6a is the osteocalcin receptor.