Project description:The transcriptome sequencing on muscle tissue from control group (CTX) and denervated group(CTX-DeN). The PI3K/Akt pathway is involved in denervation-aggravated muscle HO.
Project description:Effect of "Sensory Protection" on the transcriptome of Gastrocnemius muscle denervated by Tibial nerve transection in the rat. Comparison is made between the muscle transcriptome in denervated muscle (D), muscle undergoing surgical repair with a motor nerve (immediate repair, or IR) and muscle undergoing surgical repair with a pure sensory nerve (sensory protection, or SP). There are 6 cohorts of rats with 4 to 6 rats in each cohort:<br><br>1 Month Denervated, 1 Month Immediate Repair, 1 Month Sensory Protection, 3 Month Denervated, 3 Month Immediate Repair, 3 Month Sensory Protection. <br><br>For each animal RNA was extracted from both the experimental operated (right) gastrocnemius muscle and the contralateral control unoperated (left) gastrocnemius. Samples were run in duplicate with fluorophor reversal experiments (i.e experimental limb RNA labelled with Cy3 and control limb RNA labelled with Cy5 and vice versa) to control for possible unequal incorporation of the dyes in the reverse transcription reaction.
Project description:Belt electrode-skeletal muscle electrical stimulation (B-SES) involves the use of belt-shaped electrodes to simultaneously contract multiple muscle groups. Twitch contractions have been demonstrated to protect against denervation-induced muscle atrophy in rats, possibly via mitochondrial biosynthesis. In this study, we examined whether inducing tetanus contractions with B-SES suppresses muscle atrophy and identified the underlying molecular mechanisms. We evaluated the effects of acute (60 Hz, 5 min) and chronic (60 Hz, 5 min, every alternate day for 1 week) B-SES on the tibialis anterior (TA) and gastrocnemius (GAS) muscles in Sprague Dawley rats using belt electrodes attached to both ankle joints. In acute stimulation, a significant decrease in glycogen content in the left and right TA and GAS was observed, suggesting that B-SES causes simultaneous contractions in multiple muscle groups. B-SES also enhanced p70S6K phosphorylation, an indicator of the mechanistic target of rapamycin complex 1 activity. During chronic stimulations, rats were divided into control (CONT), denervation-induced atrophy (DEN), and DEN+electrically stimulated with B-SES (DEN+ES) groups. After 7 days of treatment, muscle wet weight (n = 8-11 for each group) and muscle fiber cross-sectional area (CSA, n = 6 for each group) of the TA and GAS muscles were reduced in the DEN and DEN+ES groups compared to those in the CON group. The DEN+ES group showed significantly higher muscle weight and CSA than the DEN group. Although RNA-seq and pathway analysis suggested that mitochondrial and ribosome biogenesis are key events in this phenomenon, mitochondrial content showed no difference. In contrast, ribosomal RNA 28S and 45S (n = 6) levels in the DEN+ES group were higher than those in the DEN group. The mRNA levels of the muscle proteolytic molecules Atrogin-1 and MuRF1 were significantly higher in DEN than in CONT but were suppressed in DEN+ES. In conclusion, tetanic electrical stimulation of both ankles using belt electrodes was effective in preventing denervation-induced atrophy in multiple muscle groups. Unlike twitch contractions, ribosomal biosynthesis plays a key role in tetanic contractions to prevent muscle atrophy.
Project description:Background: Skeletal muscle crucially depends on motor innervation, and, when damaged, on the resident muscle stem cells (MuSCs). However, the role and function of MuSCs in the context of denervation remains poorly understood. Methods: Alterations of MuSCs and their myofiber niche after denervation were investigated in a surgery-based mouse model of unilateral sciatic nerve transection. FACS-isolated MuSCs were subjected to RNA-sequencing and mass spectrometry for the analysis of intrinsic changes after denervation and in vivo assays, such as Cardiotoxin-induced muscle injury or MuSC transplantation, were performed to assess MuSC functions after denervation. Bioinformatic and histological analyses were conducted to further examine MuSCs and their myofiber niche after denervation. Results: Muscle cross section analysis revealed a significant increase in Pax7 (p-value= 0.0441), Pax7/Ki67 (p-value= 0.0023), MyoD (p-value= 0.0016) and Myog (p-value= 0.0057) positive cells after denervation, illustrating a break of quiescence and commitment to the myogenic lineage. An Omics approach showed profound intrinsic alterations on the mRNA (2613 differentially expressed genes, p-value <0.05) and protein (1096 differentially abundant proteins, q-value <0.05) level of MuSCs 21 days after denervation. Skeletal muscle injury together with denervation surgery caused deregulated regeneration, indicated by the reduced number of proliferating MuSCs and sustained high levels of developmental myosin heavy chain (Sham: 1 % vs DEN: 40 % of all myofibers), at 21 days post-surgery. In a transplantation assay, MuSCs from a denervated host were still able to engraft and fuse to form new myofibers, irrespective of the innervation status of the recipient muscle. Analysis of myofibers revealed not only massive changes in the expression profile (10492 differentially expressed genes, p-value <0.05) after denervation, but it was also shown that secretion of Opn and Tgfb1 from denervated myofibers was increased 30-fold and 6000-fold, respectively. Bioinformatic analyses indicated strong upregulation of gene expression of the transcription factor Junb in MuSCs from denervated muscles (log2 fold change = 3.27). Of interest, Tgfb1 recombinant protein was able to induce Junb gene expression in vitro, demonstrating that myofiber-secreted ligands can induce gene expression changes in MuSCs, which might result in the phenotypes observed after denervation. Conclusion: Skeletal muscle denervation is altering myofiber secretion, causing MuSC activation and profound intrinsic changes, leading to reduced regenerative capacity. As MuSCs possess a remarkable regenerative potential, they might represent a promising target for novel treatment options for neuromuscular disorders and peripheral nerve injuries.
Project description:Recent evidence has shown a crucial role for the osteoprotegerin/receptor activator of nuclear factor κ-B ligand/RANK (OPG/RANKL/RANK) signaling axis not only in bone but also in muscle tissue; however, there is still a lack of understanding of its effects on muscle atrophy. Here, we found that denervated Opg knockout mice displayed better functional recovery and delayed muscle atrophy, especially in a specific type IIB fiber. Moreover, OPG deficiency promoted milder activation of the ubiquitin-proteasome pathway, which further verified the protective role of Opg knockout in denervated muscle damage. Furthermore, transcriptome sequencing indicated that Opg knockout upregulated the expression of Inpp5k, Rbm3, and Tet2 and downregulated that of Deptor in denervated muscle. In vitro experiments revealed that satellite cells derived from Opg knockout mice displayed a better differentiation ability than those acquired from wild-type littermates. Higher expression levels of Tet2 were also observed in satellite cells derived from Opg knockout mice, which provided a mechanistic basis for the protective effects of Opg knockout on muscle atrophy. Taken together, our findings uncover the novel role of Opg in muscle atrophy process and extend the current understanding in the OPG/RANKL/RANK signaling axis.
Project description:Utilizing glycerol and cardiotoxin (CTX) injections in the tibialis anterior muscles of M. musculus provides models of skeletal muscle damages followed by skeletal muscle regeneration. In particular, glycerol-induced muscle regeneration is known to be associated with ectopic adipogenesis. We characterized genome-wide expression profiles of tibialis anterior muscles from wild-type mice injured by either glycerol or CTX injection. Our goal was to detect gene expression changes during the time course of glycerol-induced and CTX-induced muscle regeneration models, that can lead to ectopic adipocyte accumulation. Tibialis anterior muscle of 12 week old wildtype C57BL/6J male mice injected i.m with either glycerol or CTX were collected 3, 7, 14 or 21 days after injection. 6 biological replicates were used for each time points. Please note that a few replicate samples did not pass QC test, thus, were removed from the submission. Unchallenged tibialis anterior muscles from a group of 5 wildtype C57BL/6J mice were also as a control. Total RNA was extracted, QCed and hybridized to Affymetrix microarrays.
Project description:Innervation of skeletal muscle fibers plays a crucial role in the maintenance of muscle tone and normal functioning, but little is known to date about denervated muscle atrophy and its underlying mechanisms. To this end, we performed RNA sequencing of skeletal muscle from sciatic nerve-excised C57BL/6 and BALB/c mice to investigate the underlying mechanisms of denervated skeletal muscle atrophy.
Project description:Introduction:The purpose of this study is to provide athe first global transcriptomic profiling and systems analysis of BoNT-A treated muscle over a one year period. Microarray analysis was performed on rat TA muscle from 4 groups (n=4/group) at 1,4, 12 and 52 weeks after BoNT-A injection and saline injected rats at 12 weeks as control. Fold changes were computed at each time point with respect to control. Results: Dramatic transcriptional adaptation occurs at 1 week with a paradoxical increase in expression of slow and immature isoforms; increased expression of genes in competing pathways of repair and atrophy; impaired mitochondrial biogenesis and increased metal ion imbalance. ECM adaptations occurred at 4weeks to the basal lamina and fibrillar ECM. The muscle transcriptome returned to the unperturbed state 12 weeks post-injection. Conclusion: Transcriptional adaptations resemble denervated muscle albeit some differences. Overall gene expression, across time, correlates with the generally accepted BoNT-A time course. Samples of Tibialis anterior (TA) muscle from 4 groups (n=4/group) of rats sacrificed at 1, 4, 12, and 52 weeks after BoNT-A injection, subject to affymetrix microarray analysis. In addition, contralateral TA from saline injected rats extracted at 12 weeks after saline injection was used as control tissue for the microarray analysis.