Myogenic Proteins Research Articles

The role of whey protein in myogenic differentiation

Whey protein has been shown to prevent exercise-induced protein degradation and muscle damage. We hypothesized that whey protein would regulate muscle cell differentiation. Adding various concentrations of whey protein to C2C12 myoblasts induced cell differentiation and MyoD (myogenic differentiation protein) expression as well as the phosphorylation of AKT (protein kinase B). Whey protein-induced differentiation-specific markers increased the enzymatic activities of creatine kinase and citrate synthase and the expression of muscle-specific microRNA. Whey protein elevated AKT phosphorylation on Thr308 and Ser473, which was inhibited by LY294002 (a non-selective phosphoinositide 3-kinases inhibitor), suggesting that whey protein acts via PI3K (phosphatidylinositol 3-kinase). Blocking of the PI3K/AKT pathway with specific inhibitors revealed its requirement in mediating the promotive effects of whey protein on C2C12 cell differentiation. These effects of whey protein on myoblast differentiation suggest its positive influence in preventing muscle atrophy.

Primary skeletal muscle cells from chronic kidney disease patients retain hallmarks of cachexia in vitro.

BackgroundSkeletal muscle wasting and dysfunction are common characteristics noted in people who suffer from chronic kidney disease (CKD). The mechanisms by which this occurs are complex, and although progress has been made, the key underpinning mechanisms are not yet fully elucidated. With work to date primarily conducted in nephrectomy‐based animal models, translational capacity to our patient population has been challenging. This could be overcome if rationale developing work could be conducted in human based models with greater translational capacity. This could be achieved using cells derived from patient biopsies, if they retain phenotypic traits noted in vivo.MethodsHere, we performed a systematic characterization of CKD derived muscle cells (CKD; n = 10; age: 54.40 ± 15.53 years; eGFR: 22.25 ± 13.22 ml/min/1.73 m2) in comparison with matched controls (CON; n = 10; age: 58.66 ± 14.74 years; eGFR: 85.81 ± 8.09 ml/min/1.73 m2 ). Harvested human derived muscle cells (HDMCs) were taken through proliferative and differentiation phases and investigated in the context of myogenic progression, inflammation, protein synthesis, and protein breakdown. Follow up investigations exposed HDMC myotubes from each donor type to 0, 0.4, and 100 nM of IGF‐1 in order to investigate any differences in anabolic resistance.ResultsHarvested human derived muscle cells isolated from CKD patients displayed higher rates of protein degradation (P = 0.044) alongside elevated expression of both TRIM63 (2.28‐fold higher, P = 0.054) and fbox32 (6.4‐fold higher, P < 0.001) in comparison with CONs. No differences were noted in rates of protein synthesis under basal conditions (P > 0.05); however, CKD derived cells displayed a significant degree of anabolic resistance in response to IGF‐1 stimulation (both doses) in comparison with matched CONs (0.4 nm: P < 0.001; 100 nM: P < 0.001).ConclusionsIn summary, we report for the first time that HDMCs isolated from people suffering from CKD display key hallmarks of the well documented in vivo phenotype. Not only do these findings provide further mechanistic insight into CKD specific cachexia, but they also demonstrate this is a reliable and suitable model in which to perform targeted experiments to begin to develop novel therapeutic strategies targeting the CKD associated decline in skeletal muscle mass and function.

Laminin-111-Enriched Fibrin Hydrogels Enhance Functional Muscle Regeneration Following Trauma.

Volumetric muscle loss (VML) is the surgical or traumatic loss of skeletal muscle, which can cause loss of limb function or permanent disability. VML injuries overwhelms the endogenous regenerative capacity of skeletal muscle and results in poor functional healing outcomes. Currently, there are no approved tissue engineering treatments for VML injuries. In this study, fibrin hydrogels enriched with laminin-111 (LM-111; 50-450 μg/mL) were used for the treatment of VML of the tibialis anterior in a rat model. Treatment with fibrin hydrogel containing 450 μg/mL of LM-111 (FBN450) improved muscle regeneration following VML injury. FBN450 hydrogel treatment increased the relative proportion of contractile to fibrotic tissue as indicated by the myosin: collagen ratio on day 28 post-VML injury. FBN450 hydrogels also enhanced myogenic protein expression and increased the quantity of small to medium size myofibers (500-2000 μm2) as well as innervated myofibers. Improved contractile tissue deposition due to FBN450 hydrogel treatment resulted in a significant improvement (∼60%) in torque production at day 28 postinjury. Taken together, these results suggest that the acellular FBN450 hydrogels provide a promising therapeutic strategy for VML that is worthy of further investigation. Impact statement Muscle trauma accounts for 50-70% of total military injuries and complications involving muscle result in ∼80% of delayed amputations. The lack of a clinical standard of care for volumetric muscle loss (VML) injuries presents an opportunity to develop novel regenerative therapies and improve healing outcomes. Laminin-111-enriched fibrin hydrogel may provide a promising therapy for VML that is worthy of further investigation. The acellular nature of these hydrogels will allow for easy off the shelf access to critically injured patients and fewer regulatory hurdles during commercialization.

Effect of ultrasonic thawing on the physicochemical properties, freshness, and protein-related properties of frozen large yellow croaker (Pseudosciaena crocea).

Ultrasonic treatment (UT) was used to thaw large yellow croaker in this study, and the effect of various ultrasonic power levels on the quality of large yellow croaker was evaluated after thawing. The effects of ultrasonic on water holding capacity (WHC), moisture distribution, thiobarbituric acid-reactive substance (TBARs), total volatile base nitrogen (TVB-N), ATP degradation (related to K value), surface color change, free amino acid (FAA) content, total sulfhydryl group (SH) content, Fourier transform infrared absorption spectra (FT-IR), fluorescence emission spectra, and microscopic observations of large yellow croaker myofibrillar proteins were investigated. The thawing times of the control sample, 200UT, 240UT, 280UT, and 320UT samples were 1750, 1190, 810, 580, and 570 s, respectively, which indicated that ultrasonic radiation could improve thawing efficiency. Additionally, ultrasonic thawing maintained better freshness and color and inhibited lipid oxidation. Compared with fresh samples, the TVB-N of large yellow croaker thawed by ultrasonication increased by 12.68%, and the K value increased by 0.9%. The 240UT sample had tightly arranged myofibrils and fewer changes in the structures of myogenic fibrillar proteins than the fresh samples, and the SH content of 240UT was decreased by 8.17%. Use of excessive ultrasonic power (320 W) damaged the protein microstructure and the microstructure of large yellow croaker. In conclusion, sample 240UT maintained the quality of large yellow croaker better with minimal damage, which is recommended for rapid thawing. PRACTICAL APPLICATION: Ultrasonic waves improve the thawing efficiency of large yellow croaker and maintain the freshness and color of the fish. According to results, sample 240UT exhibited slight changes in the structure of the myofibril protein, but excessive ultrasonic power destroyed the microstructure and protein structure. Appropriate ultrasonic treatment to the thawing of fish has good prospects.

Alcalase Potato Protein Hydrolysate-PPH902 Enhances Myogenic Differentiation and Enhances Skeletal Muscle Protein Synthesis under High Glucose Condition in C2C12 Cells.

Sarcopenia is an aging associated disorder involving skeletal muscle atrophy and a reduction in muscle strength, and there are no pharmaceutical interventions available thus far. Moreover, conditions such as hyperglycaemia are known to further intensify muscle degradation. Therefore, novel strategies to attenuate skeletal muscle loss are essential to enhance muscle function and thereby improve the quality of life in diabetic individuals. In this study, we have investigated the efficiency of a potato peptide hydrolysate PPH902 for its cytoprotective effects in skeletal muscle cells. PPH902 treatment in C2C12 cells showed the dose-dependent activation of the Akt/mTOR signalling pathway that is involved in skeletal myogenesis. According to Western blotting analysis, PPH902 induced the phosphorylation of Akt, mTOR proteins and induced the myogenic differentiation of C2C12 myoblasts in a differentiation medium. The phosphorylation myogenic transcription factor Foxo3A was also found to be increased in the cells treated with PPH902. In addition, treatment with PPH902 ameliorated the high glucose induced reduction in cell viability in a dose-dependent manner. Moreover, the number of myotubes in a differentiation medium reduced upon high glucose challenge, but treatment with PPH902 increased the number of differentiated myotubes. Further, the phosphorylations of AMPK and mitochondrial-related transcription factors such as PGC-1α were suppressed upon high glucose challenge but PPH902 treatment restored the protein levels. We demonstrate, for the first time, that a specific potato peptide has a therapeutic effect against sarcopenia. In addition, PPH902 improved the myogenic differentiation and their mitochondrial biogenesis and further improved myogenic protein and inhibited muscle protein degradation in C2C12 cells challenged under a high glucose condition.

ZSWIM8 is a myogenic protein that partly prevents C2C12 differentiation

Cell adhesion molecule-related/downregulated by oncogenes (Cdon) is a cell-surface receptor that mediates cell–cell interactions and positively regulates myogenesis. The cytoplasmic region of Cdon interacts with other proteins to form a Cdon/JLP/Bnip-2/CDC42 complex that activates p38 mitogen-activated protein kinase (MAPK) and induces myogenesis. However, Cdon complex may include other proteins during myogenesis. In this study, we found that Cullin 2-interacting protein zinc finger SWIM type containing 8 (ZSWIM8) ubiquitin ligase is induced during C2C12 differentiation and is included in the Cdon complex. We knocked-down Zswim8 in C2C12 cells to determine the effect of ZSWIM8 on differentiation. However, we detected neither ZSWIM8-dependent ubiquitination nor the degradation of Bnip2, Cdon, or JLP. In contrast, ZSWIM8 knockdown accelerated C2C12 differentiation. These results suggest that ZSWIM8 is a Cdon complex-included myogenic protein that prevents C2C12 differentiation without affecting the stability of Bnip2, Cdon, and JLP.

Effects of Root Extract of Morinda officinalis in Mice with High-Fat-Diet/Streptozotocin-Induced Diabetes and C2C12 Myoblast Differentiation.

Type 2 diabetes is the most common type of diabetes and causes a decline in muscle quality. In this study, we investigated the effects of the root extract of Morinda officinalis (MORE) on skeletal muscle damage in mice with high-fat-diet (HFD)/streptozotocin (STZ)-induced diabetes and the expression of myogenic and biogenesis regulatory proteins in C2C12 myoblast differentiation. An in vivo model comprised C57BL/6N mice fed HFD for 8 weeks, followed by a single injection of STZ at 120 mg/kg. MORE was administered at 100 and 200 mg/kg once daily (p.o.) for 4 weeks. The changes in body weight, calorie intake, and serum levels of glucose, insulin, total cholesterol (TCHO), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), aspartate transaminase (AST), and alanine aminotransferase (ALT) were investigated in diabetic mice. The histological changes in the gastrocnemius muscle were observed by H&E staining, and then the myofiber size was measured. The expression of the myogenic (MHC, myogenin, and MyoD) and biogenesis (PGC-1α, SIRT1, NRF1, and TFAM) regulatory proteins was examined in the muscle tissues and differentiated C2C12 myoblasts by Western blot, respectively. The administration of MORE at 200 mg/kg in mice with HFD/STZ-induced diabetes significantly reduced weight gains, calorie intake, insulin resistance, and serum levels of glucose, TCHO, LDL-C, AST, and ALT. MORE administration at 100 and 200 mg/kg significantly increased serum insulin and HDL-C levels in diabetic mice. In addition, MORE significantly increased the expression of MHC, myogenin, MyoD, PGC-1α, SIRT1, NRF1, and TFAM in muscle tissues as well as increased the myofiber size in diabetic mice. In C2C12 myoblast differentiation, MORE treatment at 0.5, 1, and 2 mg/mL significantly increased the expression of myogenic and biogenesis regulatory proteins in a dose-dependent manner. MORE improves diabetes symptoms in mice with HFD/STZ-induced diabetes by improving muscle function. This suggests that MORE could be used to prevent or treat diabetes along with muscle disorders.

AMP-Activated Protein Kinase Abundance and Activation is increased with the β-Adrenergic agonist Zilpaterol Hydrochloride in Muscle from Feedlot Cattle

The objective of this research was to evaluate the effect of Zilpaterol Hydrochloride (ZH) on myogenic or adipogenic gene and protein expression in skeletal muscle. Two feeding trials and one cell culture experiments were conducted. Semimembranosus muscle tissue was collected from steers that had been fed a diet containing 8.3 mg of ZH/kg DM for the last 0 or 20 d of the finishing period with a 3 d withdrawal period. To test the mode of action an in vitromodel was used with, isolated bovine satellite cells isolated from muscle tissue. Real Time-QPCR (RTQPCR) was used to measure the relative mRNA abundance of Adenosine Monophosphate Protein Kinase α (AMPK), Myosin Heavy Chain (MHC) I, MHCIIA, MHCIIX, Insulin-like Growth Factor I (IGF-I), β-adrenergic receptor (βAR) 1 and 2, peroxisome proliferator-activated receptor gamma (PPARγ), and Stearoyl-CoA Desaturase (SCD). Western blotting was used to measure the relative protein abundance of AMPK and Phosphorylated-AMPK (pAMPK). No differences were detected in relative mRNA abundance of AMPK, MHCIIA, IGF-I, βAR1 and βAR2. However, MHCI, SCD, and PPARγ mRNA expression was decreased and MHCIIX mRNA increased from ZH fed cattle compared to non-ZH. For one experiment, AMPK protein expression increased, while in another experiment, AMPK phosphorylation increased with ZH fed animals. The increase in MHCIIX mRNA with ZH fed cattle indicated the start of a fiber type shift towards larger diameter fibers. This shift may have been due to increased expression and phosphorylation of AMPK. These data suggest that the shift increase in MHCIIX was likely due to the ZH administration.

Administration of tauroursodeoxycholic acid attenuates dexamethasone-induced skeletal muscle atrophy

Glucocorticoids are known to induce skeletal muscle atrophy by suppressing protein synthesis and promoting protein degradation. Tauroursodeoxycholic acid (TUDCA) has beneficial effects in several diseases, such as hepatobiliary disorders, hindlimb ischemia and glucocorticoid-induced osteoporosis. However, the effects of TUDCA on glucocorticoid -induced skeletal muscle atrophy remains unknown. Therefore, in the present research, we explored the effects of TUDCA on dexamethasone (DEX)-induced loss and the potential mechanisms involved. We found TUDCA alleviated DEX-induced muscle wasting in C2C12 myotubes, identified by improved myotube differentiation index and expression of myogenin and MHC. And it showed that TUDCA activated the Akt/mTOR/S6K signaling pathway and inhibited FoxO3a transcriptional activity to decreased expression of MuRF1 and Atrogin-1, while blocking Akt by MK2206 blocked these effects of TUDCA on myotubes. Besides, TUDCA also attenuated DEX-induced apoptosis of myotubes. Furthermore, TUDCA was administrated to the mouse model of DEX-induced skeletal muscle atrophy. The results showed that TUDCA improved DEX-induced skeletal muscle atrophy and weakness (identified by increased grip strength and prolonged running exhaustive time) in mice by suppression of apoptosis, reduction of protein degradation and promotion of protein synthesis. Taken together, our research proved for the first time that TUDCA protected against DEX-induced skeletal muscle atrophy not only by improving myogenic differentiation and protein synthesis, but also through decreasing protein degradation and apoptosis of skeletal muscle.

Betaine, a component of Lycium chinense, enhances muscular endurance of mice and myogenesis of myoblasts.

Sarcopenia is a disease characterized by the loss of muscle mass and function that occurs mainly in older adults. The present study was designed to investigate the hypothesis that water extract of Lycium chinense (WELC) would improve muscle function and promote myogenesis for sarcopenia. We investigated the effect of water extracts of L. chinense on muscular endurance function and myogenesis to examine its efficacy in sarcopenia. Intake of WELC‐containing cheese enhanced the muscular endurance function of mice in treadmill endurance tests. In addition, the cross‐sectional areas of muscle fibers in the gastrocnemius muscle of L. chinense‐fed mice were greater than that of control mice. Furthermore, WELC and its key component marker substance betaine promoted myogenesis of myoblasts by increasing the expression of the myogenic protein myosin heavy chain 3 (Myh3) and myotube formation. Taken together, our results suggest that L. chinense may potentially be useful in the development of preventive and therapeutic agents for sarcopenia, as well as in providing basic knowledge on myogenesis and muscular functions.

Knockdown of CNN3 Impairs Myoblast Proliferation, Differentiation, and Protein Synthesis via the mTOR Pathway.

BackgroundMyogenesis is a complex process that requires optimal outside–in substrate–cell signaling. Calponin 3 (CNN3) plays an important role in regulating myogenic differentiation and muscle regeneration; however, the precise function of CNN3 in myogenesis regulation remains poorly understood. Here, we investigated the role of CNN3 in a knockdown model in the mouse muscle cell line C2C12.MethodsMyoblast proliferation, migration, differentiation, fusion, and protein synthesis were examined in CNN3 knockdown C2C12 mouse muscle cells. Involvement of the mTOR pathway in CNN3 signaling was explored by treating cells with the mTOR activator MHY1485. The regulatory mechanisms of CNN3 in myogenesis were further examined by RNA sequencing and subsequent gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis (GSEA).ResultsDuring proliferation, CNN3 knockdown caused a decrease in cell proliferation and migration. During differentiation, CNN3 knockdown inhibited myogenic differentiation, fusion, and protein synthesis in C2C12 cells via the AKT/mTOR and AMPK/mTOR pathways; this effect was reversed by MHY1485 treatment. Finally, KEGG and GSEA indicated that the NOD-like receptor signaling pathway is affected in CNN3 knockdown cell lines.ConclusionCNN3 may promote C2C12 cell growth by regulating AKT/mTOR and AMPK/mTOR signaling. The KEGG and GSEA indicated that inhibiting CNN3 may activate several pathways, including the NOD-like receptor pathway and pathways involved in necroptosis, apoptosis, and inflammation.

The intestinal microbiota contributes to the growth and physiological state of muscle tissue in piglets

Although the importance of the intestinal microbiota in host growth and health is well known, the relationship between microbiota colonization and muscle development is unclear. In this study, the direct causal effects of the colonization of gut microorganisms on the muscle tissue of piglets were investigated. The body weight and lean mass of germ-free (GF) piglets were approximately 40% lower than those of normal piglets. The deletion of the intestinal microbiota led to weakened muscle function and a reduction in myogenic regulatory proteins, such as MyoG and MyoD, in GF piglets. In addition, the blinded IGF1/AKT/mTOR pathway in GF piglets caused muscle atrophy and autophagy, which were characterized by the high expression of Murf-1 and KLF15. Gut microbiota introduced to GF piglets via fecal microbiota transplantation not only colonized the gut but also partially restored muscle growth and development. Furthermore, the proportion of slow-twitch muscle fibers was lower in the muscle of GF piglets, which was caused by the reduced short-chain fatty acid content in the circulation and impaired mitochondrial function in muscle. Collectively, these findings suggest that the growth, development and function of skeletal muscle in animals are mediated by the intestinal microbiota.

Effects of ploidy and nutritional conditions on muscle morphology, proliferation and myogenic proteins expression in Rhamdia quelen larvae

Although Rhamdia quelen is a promising species for farming in South America, many aspects of its development and optimal conditions of culture remain unknown. In this sense, we explore muscle development and some proteins related to myogenic process in diploid and triploid larvae submitted to fasting-refeeding. Regarding muscle morphology, within diploid groups, fasted larvae (FD) showed a significant decrease in white muscle fiber area compared with control (CD) and refed (RD-1) groups. Then, when food was provided, area values restored nearly to control. Based on these results, it is probable that temporary muscle fiber atrophy takes place in fasted diploid fish. Conversely, no significant morphological changes were observed among triploid groups. When the effects of ploidy on somatic growth were assessed, FD and RT-1 groups registered a significantly higher percentage of fibers with an area smaller than 500 μm2 compared with fasted triploid larvae (FT) and RD-1 groups, respectively. Additionally, immunolocalization of the proliferating cell nuclear antigen (PCNA) decreased during starvation in fish of both ploidies and only recovered to normal after refeeding in triploid fish. An increase in PCNA related to ploidy was detected in CD and RD-1 compared with their triploid counterparts. In relation to myogenic proteins, Myog showed a significant increase expression in diploid larvae during starvation. Mstn was not affected by ploidy or alimentary variations. Our results show that diploid fish are more affected by short-term starvation than triploid fish, which could be indicative of differential physiological responses of diploid and triploid larvae to alimentary changes in culture. This might be relevant to optimize conditions of culture for both diploid and triploid fish.

Rbm24 displays dynamic functions required for myogenic differentiation during muscle regeneration

Skeletal muscle has a remarkable capacity of regeneration after injury, but the regulatory network underlying this repair process remains elusive. RNA-binding proteins play key roles in the post-transcriptional regulation of gene expression and the maintenance of tissue homeostasis and plasticity. Rbm24 regulates myogenic differentiation during early development, but its implication in adult muscle is poorly understood. Here we show that it exerts multiple functions in muscle regeneration. Consistent with its dynamic subcellular localization during embryonic muscle development, Rbm24 also displays cytoplasm to nucleus translocation during C2C12 myoblast differentiation. In adult mice, Rbm24 mRNA is enriched in slow-twitch muscles along with myogenin mRNA. The protein displays nuclear localization in both slow and fast myofibers. Upon injury, Rbm24 is rapidly upregulated in regenerating myofibers and accumulates in the myonucleus of nascent myofibers. Through satellite cell transplantation, we demonstrate that Rbm24 functions sequentially to regulate myogenic differentiation and muscle regeneration. It is required for myogenin expression at early stages of muscle injury and for muscle-specific pre-mRNA alternative splicing at late stages of regeneration. These results identify Rbm24 as a multifaceted regulator of myoblast differentiation. They provide insights into the molecular pathway orchestrating the expression of myogenic factors and muscle functional proteins during regeneration.

MYOD1 as a prognostic indicator in rhabdomyosarcoma.

Rhabdomyosarcoma (RMS) is characterized by the expression of the myogenic regulatory protein MYOD1. Histologic types include alveolar, embryonal (ERMS), and spindle cell sclerosing RMS (SRMS). SRMS harbors MYOD1 mutations in a subset of adult cases in association with poor prognosis. To study the level of MYOD1 protein expression and its clinical significance, we have analyzed variable numbers of pediatric (<18years of age) and adult (age range ≥18 to 35years) ERMS and SRMS cases for presence or absence of MYOD1 immunoreactivity in correlation with clinical outcome and MYOD1 L122R mutations. Lack of MYOD1 immunoreactivity, identified in 23.8% of nonalveolar RMS (non-ARMS) cases, was more prevalent in SRMS (44%) than ERMS (17.2%) and was significantly associated with low overall survival and unfavorable tumor sites (p<.05). Lack of MYOD1 immunoreactivity was not associated with MYOD1 L122R mutations, which were identified in 3/37 (8%) cases including only two of 31 (6.5%) pediatric cases, one of 11 or 9% pediatric SRMS, and one case of infant ERMS. These studies highlight the prognostic role of MYOD1 in non-ARMS. Lack of MYOD1 immunoreactivity is associated with poor prognosis in ERMS and SRMS. MYOD1 gene mutations are generally infrequent in pediatric RMS. Although mutations are predominant in SRMS, they may exceptionally occur in infantile ERMS.

MiR-1290 promotes myoblast differentiation and protects against myotube atrophy via Akt/p70/FoxO3 pathway regulation

BackgroundSarcopenia is a common skeletal disease related to myogenic disorders and muscle atrophy. Current clinical management has limited effectiveness. We sought to investigate the role of miR-1290 in myoblast differentiation and muscle atrophy.MethodsBy transfecting miR-1290 into C2C12 cells, we investigated whether miR-1290 regulates myogenesis and myotube atrophy via AKT/P70 signaling pathway. MHC staining was performed to assess myoblast differentiation. Differentiation-related MHC, Myod, and Myog protein levels, and atrophy-related MuRF1 and atrogin-1 were explored by western blot. An LPS-induced muscle atrophy rat model was developed. RT-PCR was conducted to analyze miR-1290 serum levels in muscle atrophy patients and normal controls (NCs).ResultsThe miR-1290 transfection increased MHC-positive cells and MHC, Myod, and Myog protein levels in the miR-1290 transfection group, demonstrating that miR-1290 promoted C2C12 myoblast differentiation. Myotube diameter in the miR-1290 transfection group was higher than in the TNF-α-induced model group. Western blot analysis showed decreased MuRF1 and atrogin-1 levels in the miR-1290 transfection group compared with the model group, demonstrating that miR-1290 protected against myoblast cellular atrophy. Luciferase assay and western blot analysis showed that miR-1290 regulation was likely caused by AKT/p70/FOXO3 phosphorylation activation. In the LPS-induced muscle atrophy rat model, miR-1290 mimics ameliorated gastrocnemius muscle loss and increased muscle fiber cross-sectional area. Clinically, miR-1290 serum level was significantly decreased in muscle atrophy patients.ConclusionsWe found that miR-1290 enhances myoblast differentiation and inhibits myotube atrophy through Akt/p70/FoxO3 signaling in vitro and in vivo. In addition, miR-1290 may be a potential therapeutic target for sarcopenia treatment.

Magnesium supplementation enhances mTOR signalling to facilitate myogenic differentiation and improve aged muscle performance.

Magnesium (Mg2+), as an essential mineral, supports and sustains the health and activity of the organs of the human body. Despite some clinical evidence on the association of Mg2+ deficiency with muscle regeneration dysfunction and sarcopenia in older-aged individuals, there is no consensus on the action mode and molecular mechanism by which Mg2+ influences aged muscle size and function. Here, we identified the appropriate Mg2+ environment that promotes the myogenic differentiation and myotube hypertrophy in both C2C12 myoblast and primary aged muscle stem cell (MuSC). Through animal experiments, we demonstrated that Mg2+ supplementation in aged mice significantly promotes muscle regeneration and conserves muscle mass and strength. Mechanistically, Mg2+ stimulation activated the mammalian target of rapamycin (mTOR) signalling, inducing the myogenic differentiation and protein synthesis, which consequently offers protections against the age-related decline in muscle regenerative potential and muscle mass. These findings collectively provide a promising therapeutic strategy for MuSC dysfunction and sarcopenia through Mg2+ supplementation in the elderly.

Genome-wide analysis of chromatin structure changes upon MyoD binding in proliferative myoblasts during the cell cycle.

MyoD, a myogenic differentiation protein, has been studied for its critical role in skeletal muscle differentiation. MyoD-expressing myoblasts have a potency to be differentiated with proliferation of ectopic cells. However, little is known about the effect on chromatin structure of MyoD binding in proliferative myoblasts. In this study, we evaluated the chromatin structure around MyoD-bound genome regions during the cell cycle by chromatin immunoprecipitation sequencing. Genome-wide analysis of histone modifications was performed in proliferative mouse C2C12 myoblasts during three phases (G1, S, G2/M) of the cell cycle. We found that MyoD-bound genome regions had elevated levels of active histone modifications, such as H3K4me1/2/3 and H3K27ac, compared with MyoD-unbound genome regions during the cell cycle. We also demonstrated that the elevated H3K4me2/3 modification level was maintained during the cell cycle, whereas the H3K27ac and H3K4me1 modification levels decreased to the same level as MyoD-unbound genome regions during the later phases. Immunoblot analysis revealed that MyoD abundance was high in the G1 phase then decreased in the S and G2/M phases. Our results suggest that MyoD binding formed selective epigenetic memories with H3K4me2/3 during the cell cycle in addition to myogenic gene induction via active chromatin formation coupled with transcription.

Effect of taurine associated gold nanoparticles on oxidative stress in muscle of mice exposed to overuse model.

Muscle overuse and its consequent muscle damage has no cure. Therefore, the present study aimed to investigate the regulatory role of tau-AuNPs on muscle recovery of muscle overuse model. The animals (Male Swiss mice) were randomly divided into four groups: Control (Ctr; n=6); tau-AuNPs (n=6); overuse (n=6); and overuse plus tau-AuNPs (n=6). Exercise sessions were performed for 21 consecutive days, and one exercise model was applied daily in the following sequence: low intensity, moderate intensity, and high intensity. The mice were then sacrificed. The quadriceps muscles were surgically removed for subsequent biochemical analysis (oxidative stress parameters, DNA damage markers and muscle differentiation protein). The overuse group significantly increased the oxidative stress parameters and DNA damage markers, whereas tau-AuNPs significantly decreased the oxidative stress parameters in the overuse animal model. However, there were no significant differences observed between overuse group and overuse plus tau-AuNPs administrated group in relation to DNA damage markers including DNA damage frequency and index levels when compared to control and tau-AuNPs groups. Muscle differentiation protein Myf-5 was increased in the overuse plus tau-AuNPs administration group when compared to control group. In conclusion, tau-AuNPs had significant effect on reducing oxidative stress parameters and increasing myogenic regulatory protein Myf-5 in the overuse group. However, it did not have significant effect on reducing DNA damage.

Expression of titin-linked putative mechanosensing proteins in skeletal muscle after power resistance exercise in resistance-trained men.

Little is known about the molecular responses to power resistance exercise that lead to skeletal muscle remodeling and enhanced athletic performance. We assessed the expression of titin-linked putative mechanosensing proteins implicated in muscle remodeling: muscle ankyrin repeat proteins (Ankrd 1, Ankrd 2, and Ankrd 23), muscle-LIM proteins (MLPs), muscle RING-finger protein-1 (MuRF-1), and associated myogenic proteins (MyoD1, myogenin, and myostatin) in skeletal muscle in response to power resistance exercise with or without a postexercise meal, in fed, resistance-trained men. A muscle sample was obtained from the vastus lateralis of seven healthy men on separate days, 3 h after 90 min of rest (Rest) or power resistance exercise with (Ex + Meal) or without (Ex) a postexercise meal to quantify mRNA and protein levels. The levels of phosphorylated HSP27 (pHSP27-Ser15) and cytoskeletal proteins in muscle and creatine kinase activity in serum were also assessed. The exercise increased (P ≤ 0.05) pHSP27-Ser15 (∼6-fold) and creatine kinase (∼50%), whereas cytoskeletal protein levels were unchanged (P > 0.05). Ankrd 1 (∼15-fold) and MLP (∼2-fold) mRNA increased, whereas Ankrd 2, Ankrd 23, MuRF-1, MyoD1, and myostatin mRNA were unchanged. Ankrd 1 (∼3-fold, Ex) and MLPb (∼20-fold, Ex + Meal) protein increased, but MLPa, Ankrd 2, Ankrd 23, and the myogenic proteins were unchanged. The postexercise meal did not affect the responses observed. Power resistance exercise, as performed in practice, induced subtle early responses in the expression of MLP and Ankrd 1 yet had little effect on the other proteins investigated. These findings suggest possible roles for MLP and Ankrd 1 in the remodeling of skeletal muscle in individuals who regularly perform this type of exercise.NEW & NOTEWORTHY This is the first study to assess the early changes in the expression of titin-linked putative mechanosensing proteins and associated myogenic regulatory factors in skeletal muscle after power resistance exercise in fed, resistance-trained men. We report that power resistance exercise induces subtle early responses in the expression of Ankrd 1 and MLP, suggesting these proteins play a role in the remodeling of skeletal muscle in individuals who regularly perform this type of exercise.