Project description:Muscle contraction during exercise is the major stimulus for the release of peptides and proteins (myokines) that are supposed to take part in the benefical adaptation to exercise. We hypothesize that application of an in vitro exercise stimulus as electric pulse stimulation (EPS) to human myotubes enables the investigation of the human muscle secretome in a clearly defined model. We applied EPS for 24 h to primary human myotubes and studied the whole genome-wide transcriptional response and as well as the release of candidate myokines. We observed 183 differentially regulated transcripts with fold-changes > 1.3. The transcriptional response resembles several properties of the in vivo situation in the skeletal muscle after endurance exercise, namely significant enrichment of pathways associated with interleukin and chemokine signaling, lipid metabolism, and anti-oxidant defense; notably without increased release of creatin kinase. Multiplex immunoassays verified the translation of the transcriptional response of several myokines into high secretion levels (IL6, IL8, CXCL1, LIF, CSF3, IL1B, TNF) and identified an increased secretion of additional cytokines (IL2, IL4, IL13, IL17A). Inhibitor studies and immunoblotting revealed the participation of ERK1/2 and AMPK dependent pathways in the upregulation of myokines. To conclude our data highlight the importance of skeletal muscle cells per se as endocrine cells. This in vitro exercise model is not only suitable to identify known and novel exercise-regulated myokines but it might be applied to primary human myotubes obtained from different muscle biopsy donors to study molecular mechanisms of the individual response to exercise. We performed gene expression microarray analysis of myotubes in vitro stimulated by EPS and control myotubes
Project description:Muscle contraction during exercise is the major stimulus for the release of peptides and proteins (myokines) that are supposed to take part in the benefical adaptation to exercise. We hypothesize that application of an in vitro exercise stimulus as electric pulse stimulation (EPS) to human myotubes enables the investigation of the human muscle secretome in a clearly defined model. We applied EPS for 24 h to primary human myotubes and studied the whole genome-wide transcriptional response and as well as the release of candidate myokines. We observed 183 differentially regulated transcripts with fold-changes > 1.3. The transcriptional response resembles several properties of the in vivo situation in the skeletal muscle after endurance exercise, namely significant enrichment of pathways associated with interleukin and chemokine signaling, lipid metabolism, and anti-oxidant defense; notably without increased release of creatin kinase. Multiplex immunoassays verified the translation of the transcriptional response of several myokines into high secretion levels (IL6, IL8, CXCL1, LIF, CSF3, IL1B, TNF) and identified an increased secretion of additional cytokines (IL2, IL4, IL13, IL17A). Inhibitor studies and immunoblotting revealed the participation of ERK1/2 and AMPK dependent pathways in the upregulation of myokines. To conclude our data highlight the importance of skeletal muscle cells per se as endocrine cells. This in vitro exercise model is not only suitable to identify known and novel exercise-regulated myokines but it might be applied to primary human myotubes obtained from different muscle biopsy donors to study molecular mechanisms of the individual response to exercise.
Project description:To evaluate transcriptomic changes induced by in vitro exercise, we established two in vitro exercise models; EPS (electrical pulse stimulation and clenbuterol treatment). As for clen-buterol treatment, differentiated C2C12 myotubes were treated by 30 ng/ml clenbuterol for 1 hour and control and clenbuterol treated C2C12 myotubes were analyzed by RNA-sequencing. As for an EPS model, EPS was applied to differentiated C2C12 myotubes for 24 hours and control and EPS applied C2C12 myotubes were analyzed by RNA-sequencing.
Project description:Skeletal muscle mediates the beneficial effects of exercise, thereby improving insulin sensitivity and reducing the risk for type 2 diabetes. Current skeletal-muscle-models in vitro are incapable of fully recapitulating its physiological functions especially regarding exercise. Supplementation of IGF1, a growth factor secreted by myofibers in vivo, might help to overcome these limitations. Primary human CD56-positive myoblasts were differentiated into myotubes in the presence/absence of IGF1 in serum-free medium for 10 days. Daily collected samples were analyzed by proteomics, qRT-PCR and myotube contractibility via electrical-pulse-stimulation (EPS). Mitochondrial respiration and glucose uptake were measured. IGF1-supported differentiation formed thicker multinucleated myotubes showing physiological contraction upon EPS following day 6 while myotubes without IGF1 were almost incapable of contraction. IGF1-treatment upregulated particularly muscle-specific proteins that contribute to myofibril and sarcomere assembly, striated muscle contraction, and ATP production. Elevated PPARGC1A, MYH7 and reduced MYH1/2 suggest a switch towards a more oxidative phenotype in line with elevated mitochondrial respiration. IGF1-treatment also upregulated expression of GLUT4 and increased insulin-dependent glucose uptake. To conclude, utilizing IGF1, we engineered human myotubes that recapitulate the physiological traits of skeletal muscle in vivo vastly superior to established protocols. This novel model enables investigation of exercise on a molecular level, drug screening and interorgan-crosstalk by transfer to organ-on-chip.
Project description:We hypothesized that muscle contraction produces a cellular stress signal capable to increase lipolysis to sustain fuel availability during exercise. The aim of the present study was to identify novel exercise-regulated myokines, aka exerkines, able to promote lipolysis in human adipocytes. To this end, human primary myotubes from lean healthy volunteers were submitted to electrical pulse stimulation to mimic either acute intense or chronic moderate exercise. Conditioned media experiments with hMADS adipocytes were performed. Unbiased proteomic and ELISA analyses were applied in conditioned media and human plasma samples. Real-time qPCR was performed in cultured myotubes and muscle biopsy samples.
Project description:Various studies have shown that aerobic exercise can prevent or alleviate cancer-induced muscle wasting. To reproduce at least partially in vitro some molecular differences of aerobic muscle exercise that are independent from systemic inflammation or the hormonal milieu, we infected fully differentiated myotubes with adenoviruses expressing PGC1α, one of the main transcriptional coactivators involved in muscle adaptation to endurance exercise. We then compared the effect of PGC1α expression at 48h in myotubes infected with GFP, used as control.
Project description:We have used a combined transcriptome-proteome approach to describe how EPS affected the cargo of extracellular vesicles derived from myotubes from morbidly obese patients with T2D, and revealed several new factors, both miRs and proteins, that might act as exercise factors. During exercise, skeletal muscles release signaling factors that communicate with other organs and mediate beneficial effects of exercise. These factors include myokines, metabolites, and extracellular vesicles (EVs). In the present study, we have examined how electrical pulse stimulation (EPS) of myotubes, a model of exercise, affects the cargo of released EVs. Chronic low frequency EPS was applied for 24 h to human myotubes isolated and differentiated from biopsy samples from 6 morbidly obese females with T2D, and EVs, both exosomes and microvesicles (MV), were isolated from cell media 24 h thereafter.Protein content was assessed by high-resolution proteomic analysis (LC-MS/MS), non-coding RNA was quantified by Affymetrix GeneChip Multispecies miRNA-4_0 Array and Flash Tag TM Biotin RNA labelling, Thermo Fisher), and selected microRNAs (miRs) validated by real time RT-qPCR. We found that human myotubes secrete both exosomes and MV. EPS treatment of the myotubes, clearly changed the protein content of both exosomes and MV, whereas the miR content was changed only in exosomes. We suggest that skeletal muscle derived EVs can contribute to circulatory EVs and mediate beneficial effects of exercise in metabolically active organs.
Project description:The Skeletal muscle is a metabolic active tissue that secretes various proteins. These so called myokines act auto-, para- and endocrine affecting muscle physiology and exert systemic effects on other tissues and organs. Myokines are also described to play a crucial role in the pathophysiology of metabolic diseases. Combining three different mass spectrometry based non-targeted and one antibody based targeted approach we investigated the secretome of differentiated primary human skeletal muscle cells derived from adult donors. A total of 548 non-redundant proteins were detected by combined proteomic profiling. Expression was confirmed on mRNA level for 501. Stringent consecutive filtering recruiting several database, i.e. SignalP, SecretomeP and ER_retention signals, the computational analysis assigned 306 as secretory proteins including 33 potentially novel myokines. This comprehensive profiling study of the human skeletal muscle secretome expands our knowledge of the composition of the human myokinome and further highlights the pivotal role of myokines in the regulation of multiple biological processes. We performed gene expression microarray analysis of primary human myotubes derived from twelve healthy individuals
Project description:We have used a combined transcriptome-proteome approach to describe how EPS affected the cargo of extracellular vesicles derived from myotubes from morbidly obese patients with T2D, and revealed several new factors, both miRs and proteins, that might act as exercise factors. During exercise, skeletal muscles release signaling factors that communicate with other organs and mediate beneficial effects of exercise. These factors include myokines, metabolites, and extracellular vesicles (EVs). In the present study, we have examined how electrical pulse stimulation (EPS) of myotubes, a model of exercise, affects the cargo of released EVs. Chronic low frequency EPS was applied for 24 h to human myotubes isolated and differentiated from biopsy samples from 6 morbidly obese females with T2D, and EVs, both exosomes and microvesicles (MV), were isolated from cell media 24 h thereafter.Protein content was assessed by high-resolution proteomic analysis (LC-MS/MS), non-coding RNA was quantified by Affymetrix microarray GeneChip TM Multispecies miRNA 4.0 and Flash Tag TM Biotin RNA labelling, Thermo Fisher), and selected microRNAs (miRs) validated by real time RT-qPCR. We found that human myotubes secrete both exosomes and MV. EPS treatment of the myotubes, clearly changed the protein content of both exosomes and MV, whereas the miR content was changed only in exosomes. We suggest that skeletal muscle derived EVs can contribute to circulatory EVs and mediate beneficial effects of exercise in metabolically active organs.
Project description:We have used a combined transcriptome-proteome approach to describe how EPS affected the cargo of extracellular vesicles derived from myotubes from morbidly obese patients with T2D, and revealed several new factors, both miRs and proteins, that might act as exercise factors. During exercise, skeletal muscles release signaling factors that communicate with other organs and mediate beneficial effects of exercise. These factors include myokines, metabolites, and extracellular vesicles (EVs). In the present study, we have examined how electrical pulse stimulation (EPS) of myotubes, a model of exercise, affects the cargo of released EVs. Chronic low frequency EPS was applied for 24 h to human myotubes isolated and differentiated from biopsy samples from 6 morbidly obese females with T2D, and EVs, both exosomes and microvesicles (MV), were isolated from cell media 24 h thereafter.Protein content was assessed by high-resolution proteomic analysis (LC-MS/MS), non-coding RNA was quantified by Affymetrix GeneChip Multispecies miRNA-4_0 Array microarray and Flash Tag TM Biotin RNA labelling, Thermo Fisher), and selected microRNAs (miRs) validated by real time RT-qPCR. We found that human myotubes secrete both exosomes and MV. EPS treatment of the myotubes, clearly changed the protein content of both exosomes and MV, whereas the miR content was changed only in exosomes. We suggest that skeletal muscle derived EVs can contribute to circulatory EVs and mediate beneficial effects of exercise in metabolically active organs.