Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of skeletal muscle from wild type and PGC-1 beta transgenic mice

ABSTRACT: Skeletal muscle must perform a wide range of kinds of work, and different fiber types have evolved to accommodate these different tasks. The attributes of fibers are determined in large part by the coordinated regulation of oxidative capacity, as reflected by mitochondrial content, and the specific makeup of myofibrillar proteins. Adult muscle fibers contain four myosin heavy chain isotypes: I, IIa, IIx and IIb. Type I and IIa fibers have slower twitches and are rich in mitochondria, while type IIb fibers are fast-twitch and predominantly glycolytic. The intermediate IIx fibers are less well understood. Previous work had shown that the transcriptional coactivator PGC-1 alpha could drive the formation of type I and IIa muscle fibers. We show here that mice with transgenic expression of PGC-1 beta in skeletal muscle results in marked induction of IIx fibers. The fibers in transgenic mice are rich in mitochondria and are highly oxidative. As a result, PGC-1 beta transgenic animals can perform oxidative activity for longer and at higher work loads than wild type animals. In cell culture, PGC-1 beta coactivates the MEF2 family of transcription factors to stimulate the MHC IIx promoter. Together, these data indicate that PGC-1 beta is sufficient to drive the formation in vivo of highly oxidative fibers with type IIx characteristics.

ORGANISM(S): Mus musculus

SUBMITTER: Zolt Arany

PROVIDER: E-MEXP-939 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

The transcriptional coactivator PGC-1beta drives the formation of oxidative type IIX fibers in skeletal muscle.

Arany Zoltan Z Lebrasseur Nathan N Morris Carl C Smith Eric E Yang Wenli W Ma Yanhong Y Chin Sherry S Spiegelman Bruce M BM

Cell metabolism 20070101 1

Skeletal muscle must perform different kinds of work, and distinct fiber types have evolved to accommodate these. Previous work had shown that the transcriptional coactivator PGC-1alpha drives the formation of type I and IIA muscle fibers, which are "slow-twitch" and highly oxidative. We show here that transgenic expression of PGC-1beta, a coactivator functionally similar to but distinct from PGC-1alpha, causes a marked induction of IIX fibers, which are oxidative but have "fast-twitch" biophysi ...[more]

PMID: 17189205

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Project description:Title: Total Skeletal Muscle PGC-1 Deficiency Uncouples Mitochondrial Derangements from Fiber Type Determination and Insulin Sensitivity Abstract: Evidence is emerging that the PGC-1 coactivators serve a critical role in skeletal muscle metabolism, function, and disease. Mice with total PGC-1 deficiency in skeletal muscle (PGC-1α-/- βf/f/MLC-Cre mice) were generated and characterized. PGC-1α-/-βf/f/MLC-Cre mice exhibit a dramatic reduction in exercise performance compared to single PGC-1α- or PGC-1β-deficient mice and wild-type controls. The exercise phenotype of the PGC-1α-/-βf/f/MLC-Cre mice was associated with a marked diminution in muscle oxidative capacity and mitochondrial structural derangements consistent with fusion/fission and biogenic defects together with rapid depletion of muscle glycogen stores during exercise. Surprisingly, the skeletal muscle fiber type profile of the PGC-1α-/-βf/f/MLCCre mice was not significantly different than the wild-type mice. Moreover, insulin sensitivity and glucose tolerance were also not altered in the PGC-1α-/-βf/f/MLC-Cre mice. Taken together, we conclude that PGC-1 coactivators are necessary for the oxidative and mitochondrial programs of skeletal muscle but are dispensable for fundamental fiber type determination and insulin sensitivity. RNA from PGC-1alpha-/- beta f/f/Mlc1fcre was obtained and gene expression pattern compared with PGC-1alpha -/-, PGC-1beta f/f, and PGC-1beta f/f/Mlc1fCre controls. Results file descriptions: 1. GSE23365_skfloxAKO_PPexcl_genesup_GEO-8-16-2010: This table contains genes that were upregulated ≥2.0 fold in gastrocnemius muscle from PGC-1alpha-/- - mice, PGC-1beta f/f/Mlc1fCre mice and PGC-1alpha-/- - beta f/f/Mlc1fCre mice. All groups are normalized to PGC-1beta f/f mice and values are expressed as mean±SEM. The column “description’ contains the gene name, and the column “ID” contains Agilent probe names. 2. GSE23365_skfloxAKO_PPexcl_genesdown_GEO-8-16-2010 This table contains genes that were downregulated ≤0.7 fold in gastrocnemius muscle from PGC-1alpha-/- - mice, PGC-1beta f/f/Mlc1fCre mice and PGC-1alpha-/- - beta f/f/Mlc1fCre mice. All groups are normalized to PGC-1beta f/f mice and values are expressed as mean±SEM. The column “description’ contains the gene name, and the column “ID” contains Agilent probe names.

Project description:Purpose: Reduced Representation Bisulfite Sequencing (RRBS) DNA input requirements become a challenge when working with small pools of tissue-specific cell types. We describe an application of the RRBS method to assess DNA methylation on low-DNA input from human slow-twitch (MHC I) and fast-twitch (MHC IIa) skeletal muscle fibers. Methods : Fiber-type specific (MHC I and MHC IIa muscle fibers) total DNA was extracted from vastus lateralis muscle biopsies of 8 young physically active men (~25 yrs). A total of 16 DNA samples were generated : 8 DNA samples from pure MHC I and 8 DNA samples from pure MHC IIa muscle fibers. An equal quantity of DNA (4 ng) from each sample was combined to generate a "pooled" DNA sample representing all 8 subjects for each fiber type. Two fiber-type specific "pooled" samples of 32 ng of DNA were generated for library construction and sequencing, creating a Type 1 (MHC I muscle fibers) and Type 2a (MHC IIa muscle fibers) sample. Sequencing was performed using the HiSeq 2500 (Illumina) with 50 bp paired-end read parameters. Minimum sequencing read coverage of 5 (5x) was used as the cutoff for CpG-sites inclusion in the DNA methylation analysis. Fisher’s exact test was performed on CpG-sites that overlapped (i.e. identified in both samples) Type 1 and Type 2a samples to obtain p-values that indicate the likelihood of the site being a differentially methylated CpG-site (DMS). DMS with p<0.05 were classified as hypermethylated or hypomethylated if they were more or less methylated than the Type 1 sample, which was used as the reference sample. Results: The 32 ng of DNA from fiber-type specific muscle samples (Type 1 and 2a) used in this study ensured similar sequencing quality as compared to other studies using greater DNA input (>50 ng). Mapping ratios of ~47% and bisulfite conversion rates of ~97-98% were obtained.The unique and best alignment was successfully assessed for each of 17,376,728 CpG-sites in the Type 1 sample and 17,006,993 in the Type 2a sample, which represents ~30% of the total CpG number in the human genome. We identified 143,160 differentially methylated CpG-sites (DMS) across 14,046 genes among MHC I and MHC IIa muscle fibers. The analysis revealed that some genes predominantly expressed in MHC I were hypermethylated in MHC IIa muscle fibers. Conclusion: This study validates a low-DNA input RRBS method for human skeletal muscle samples to investigate the methylation patterns at a fiber-type specific level. These are the first fiber-type specific methylation data reported from human skeletal muscle. Considering the metabolic and structural differences between MHC I and MHC IIa muscle fibers, this technique could provide novel insights into the skeletal muscle methylation profile in relation to health, performance, disease or disuse.

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.

Dataset Information

Transcription profiling of skeletal muscle from wild type and PGC-1 beta transgenic mice

Publications

The transcriptional coactivator PGC-1beta drives the formation of oxidative type IIX fibers in skeletal muscle.

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