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 microRNA-499 in skeletal muscle of transgenic mice that overexpressed miR-499. The following abstract from the submitted manuscript describes the major findings of this work. Coupling of mitochondrial function and skeletal muscle fiber type by a miR-499/Fnip1/AMPK circuit. Jing Liu, Xijun Liang, Danxia Zhou, Ling Lai, Tingting Fu, Yan Kong, Qian Zhou, Rick B. Vega, Min-Sheng Zhu, Daniel P. Kelly, Xiang Gao, and Zhenji Gan. Upon adaption of skeletal muscle to physiological and pathophysiological stimuli, muscle fiber type and mitochondrial function are coordinately regulated. Recent studies have identified pathways involved in control of contractile proteins of oxidative type fibers. However, the mechanism for coupling of mitochondrial function to muscle contractile machinery during fiber type transition remains unknown. Here, we show that the expression of the genes encoding type I myosins, Myh7/Myh7b and their intronic miR-208b/miR-499 parallels mitochondrial function during fiber type transitions. Using in vivo approaches in mice, we found that miR-499 drives a PGC-1a-dependent mitochondrial oxidative metabolism program to match shifts in slow-twitch muscle fiber composition. Mechanistically, miR-499 directly targets Fnip1, a known AMP-activated protein kinase (AMPK)-interacting protein that negatively regulates AMPK, a known activator of PGC-1a. Inhibition of Fnip1 reactivated AMPK/PGC-1a signaling and mitochondrial function in myocytes. Restoration of the expression of miR-499 in the mdx mouse model of Duchenne muscular dystrophy (DMD) reduced the severity of DMD. Thus, we have identified a miR-499/Fnip1/AMPK circuit that can serve as a mechanism to couple muscle fiber type and mitochondrial function. Keywords: muscle, contractile fiber type, mitochondrial function, microRNA, gene regulation RNA from three wild-type (non-transgenic (NTG)) and three miR-499 overexpressing (MCK-miR-499) mice was analyzed. three 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:This experiment was conducted to identify target genes of the microRNA-499 in skeletal muscle of transgenic mice that overexpressed miR-499. The following abstract from the submitted manuscript describes the major findings of this work. Coupling of mitochondrial function and skeletal muscle fiber type by a miR-499/Fnip1/AMPK circuit. Jing Liu, Xijun Liang, Danxia Zhou, Ling Lai, Tingting Fu, Yan Kong, Qian Zhou, Rick B. Vega, Min-Sheng Zhu, Daniel P. Kelly, Xiang Gao, and Zhenji Gan. Upon adaption of skeletal muscle to physiological and pathophysiological stimuli, muscle fiber type and mitochondrial function are coordinately regulated. Recent studies have identified pathways involved in control of contractile proteins of oxidative type fibers. However, the mechanism for coupling of mitochondrial function to muscle contractile machinery during fiber type transition remains unknown. Here, we show that the expression of the genes encoding type I myosins, Myh7/Myh7b and their intronic miR-208b/miR-499 parallels mitochondrial function during fiber type transitions. Using in vivo approaches in mice, we found that miR-499 drives a PGC-1a-dependent mitochondrial oxidative metabolism program to match shifts in slow-twitch muscle fiber composition. Mechanistically, miR-499 directly targets Fnip1, a known AMP-activated protein kinase (AMPK)-interacting protein that negatively regulates AMPK, a known activator of PGC-1a. Inhibition of Fnip1 reactivated AMPK/PGC-1a signaling and mitochondrial function in myocytes. Restoration of the expression of miR-499 in the mdx mouse model of Duchenne muscular dystrophy (DMD) reduced the severity of DMD. Thus, we have identified a miR-499/Fnip1/AMPK circuit that can serve as a mechanism to couple muscle fiber type and mitochondrial function. Keywords: muscle, contractile fiber type, mitochondrial function, microRNA, gene regulation
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:We analyzed the functional role of DOR (Diabetes and Obesity Regulated gene) (also named Tp53inp2) in skeletal muscle. We show that DOR has a direct impact on skeletal muscle mass in vivo. Thus, using different transgenic mouse models, we demonstrate that while muscle-specific DOR gain-of-function results in reduced muscle mass, loss-of-function causes muscle hypertrophy. DOR has been described as a protein with two different functions, i.e., a nuclear coactivator and an autophagy regulator (Baumgartner et. al., PLoS One, 2007; Francis et. al., Curr Biol, 2010; Mauvezin et. al., EMBO Rep, 2010; Nowak et. al., Mol Biol Cell, 2009). This is why we decided to analyze which of these two functions could explain the phenotype observed in our mice models. In this regard, we performed a transcriptomic analysis using microarrays looking for genes differentially expressed in the quadriceps muscle of WT and SKM-Tg mice as well as in C and SKM-KO animals. Surprisingly, only a reduced number of genes were dysregulated upon DOR manipulation and most of the genes underwent mild changes in expression. These data strongly suggest that DOR does not operate as a nuclear co-factor in mouse skeletal muscle under the conditions subjected to study. In contrast, DOR enhances basal autophagy in skeletal muscle and promotes muscle wasting when autophagy is a contributor to muscle loss. To determine the functional role of DOR in skeletal muscle, we generated transgenic mice (SKM-Tg) overexpressing DOR specifically in skeletal muscle under the Myosin-Light Chain 1 promoter/enhancer. The open reading frame of DOR was introduced in an EcoRI site in the MDAF2 vector, which contains a 1.5 kb fragment of the MLC1 promoter and 0.9 kb fragment of the MLC1/3 gene containing a 3' muscle enhancer element (Rosenthal et. al., PNAS, 1989; Otaegui et. al., FASEB J, 2003). The fragment obtained after the digestion of this construct with BssHII was the one used to generate both transgenic mouse lines. Nontransgenic littermates were used as controls for the transgenic animals (Wt). In addition, a muscle-specific DOR knock-out mouse line (SKM-KO) was also generated by crossing homozygous DOR loxP/loxP mice with a mouse strain expressing Cre recombinase under the control of the Myosin-Light Chain 1 promoter (Bothe et. al., Genesis, 2000). Deletion of exons 3 and 4 driven by Cre recombinase caused the ablation of DOR expression. Non-expressing Cre DOR loxP/loxP littermates were used as controls for knockout animals (C). Four-month-old male mice were used in all experiments. Mice were in a C57BL/6J pure genetic background.