FHL3 promotes the formation of fast glycolytic muscle fibers by interacting with YY1 and muscle glycolytic metabolism.

The proportions of the various muscle fiber types are important in the regulation of skeletal muscle metabolism, as well as animal meat production. Four-and-a-half LIM domain protein 3 (FHL3) is highly expressed in fast glycolytic muscle fibers and differentially regulates the expression of myosin heavy chain (MyHC) isoforms at the cellular level. Whether FHL3 regulates the transformation of muscle fiber types in vivo and the regulatory mechanism is unclear. In this study, muscle-specific FHL3 transgenic mice were generated by random integration, and lentivirus-mediated gene knockdown or overexpression in muscles of mice or pigs was conducted. Functional analysis showed that overexpression of FHL3 in muscles significantly increased the proportion of fast-twitch myofibers and muscle mass but decreased muscle succinate dehydrogenase (SDH) activity and whole-body oxygen consumption. Lentivirus-mediated FHL3 knockdown in muscles significantly decreased muscle mass and the proportion of fast-twitch myofibers. Mechanistically, FHL3 directly interacted with the Yin yang 1 (YY1) DNA-binding domain, repressed the binding of YY1 to the fast glycolytic MyHC2b gene regulatory region, and thereby promoted MyHC2b expression. FHL3 also competed with EZH2 to bind the repression domain of YY1 and reduced H3K27me3 enrichment in the MyHC2b regulatory region. Moreover, FHL3 overexpression reduced glucose tolerance by affecting muscle glycolytic metabolism, and its mRNA expression in muscle was positively associated with hemoglobin A1c (HbA1c) in patients with type 2 diabetes. Therefore, FHL3 is a novel potential target gene for the treatment of muscle metabolism-related diseases and improvement of animal meat production.

Fluorescent hiPSC-derived MYH6-mScarlet cardiomyocytes for real-time tracking, imaging, and cardiotoxicity assays.

Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) hold great potential in the cardiovascular field for human disease modeling, drug development, and regenerative medicine. However, multiple hurdles still exist for the effective utilization of hiPSC-CMs as a human-based experimental platform that can be an alternative to the current animal models. To further expand their potential as a research tool and bridge the translational gap, we have generated a cardiac-specific hiPSC reporter line that differentiates into fluorescent CMs using CRISPR-Cas9 genome editing technology. The CMs illuminated with the mScarlet fluorescence enable their non-invasive continuous tracking and functional cellular phenotyping, offering a real-time 2D/3D imaging platform. Utilizing the reporter CMs, we developed an imaging-based cardiotoxicity screening system that can monitor distinct drug-induced structural toxicity and CM viability in real time. The reporter fluorescence enabled visualization of sarcomeric disarray and displayed a drug dose-dependent decrease in its fluorescence. The study also has demonstrated the reporter CMs as a biomaterial cytocompatibility analysis tool that can monitor dynamic cell behavior and maturity of hiPSC-CMs cultured in various biomaterial scaffolds. This versatile cardiac imaging tool that enables real time tracking and high-resolution imaging of CMs has significant potential in disease modeling, drug screening, and toxicology testing.

Dual immunological and proliferative regulation of immune checkpoint FGL1 in lung adenocarcinoma: The pivotal role of the YY1-FGL1-MYH9 axis.

Rational: Lung cancer is the most common tumor worldwide, with the highest mortality rate and second highest incidence. Immunotherapy is one of the most important treatments for lung adenocarcinoma (LUAD); however, it has relatively low response rate and high incidence of adverse events. Herein, we explored the therapeutic potential of fibrinogen-like protein 1 (FGL1) for LUAD. Methods: Data from GEPIA and ACLBI databases were assessed to explore gene-gene correlations and tumor immune infiltration patterns. A total of 200 patients with LUAD were recruited. FGL1 levels in the serum and cellular supernatant were determined by enzyme-linked immunosorbent assay. In vitro and in vivo experiments were performed to assess the effect FGL1 on the proliferation of LUAD cells. Cocultures were performed to explore the effect of FGL1 knockdown in lung cancer cells on T cells, concerning cytokine secretion and viability. PROMO and hTFtarget databases were used for transcription factor prediction. Quantitative polymerase chain reaction (qPCR), chromatin immunoprecipitation, and dual luciferase reporter assays were performed to validate the identified transcription factor of FGL1. Immunoprecipitation, mass spectrometry and gene ontology analysis were performed to explore the downstream partners of FGL1. Results: FGL1 expression in LUAD was positively associated with PDL1, but not for PD1 expression. Moreover, FGL1 was positively associated with the CD3D expression and negatively associated with FOXP3, S100A9, and TPSB2 within the tumor site. FGL1 promotes the secretion of interleukin-2 by T cells in vitro, simultaneously inducing their apoptosis. Indeed, YY1 is the upstream molecule of FGL1 was found to be transcriptionally regulated by YY1 and to directly by to MYH9 to promote the proliferation of LUAD cells in vitro and in vivo. Conclusions: FGL1 is involved in the immunological and proliferative regulation of LUAD cells by controlling the secretion of important immune-related cytokines via the YY1-FGL1-MYH9 axis. Hence, targeting FGL1 in LUAD may pave the way for the development of new immunotherapies for tackling this malignancy.

A Phytomolecule Icariin Protects from Sarcopenia Partially by Suppressing Myosin Heavy Chain Degradation in Orchiectomized Rats.

Treatments are lacking for sarcopenia, which is an age-related disease characterized by loss of skeletal muscle mass, strength, and/or physical performance. Icariin is a phytomolecule from herbal Epimedium, a traditional Chinese medicine widely used to treat musculoskeletal disorders for thousands of years. Here the effects of icariin against sarcopenia are investigated and the underlying mechanism is elucidated. A classic rat model of bilaterally orchiectomized (ORX) is used to induce sarcopenia. After administration for 8 weeks, compared to the control group, the forelimb grip strength, the specific tetanic forces of the soleus (SOL) and extensor digitorum longus muscle (EDL) are higher, and the fiber cross-sectional areas (CSAs) of the gastrocnemius and tibialis anterior muscle are larger in the icariin group. In addition, icariin promotes mRNA and protein expressions of myosin heavy chain (MyHC) both in SOL and EDL. Mechanistically, icariin significantly suppresses the mRNA and protein expressions of FOXO3a, atrogin-1, and MuRF-1, which are related to the degradation of myosin heavy chain. Collectively, icariin protects from sarcopenia in ORX rats characterized by enhancing grip strength and skeletal muscle contraction, as well as increasing skeletal muscle CSA by inhibiting the ubiquitination degradation of the MyHC in skeletal muscle fibers.

Short Communication: Supplementation with calcium butyrate causes an increase in the percentage of oxidative fibers in equine gluteus medius muscle.

Optimal athletic performance requires meeting the energetic demands of the muscle fibers, which are a function of myosin ATPase enzymatic activity. Skeletal muscle with a predominant oxidative metabolism underlies equine athletic success. Sodium butyrate, a short-chain fatty acid, can affect muscle fiber composition in pigs. To determine if a similar scenario exists in horses, 12 adult Thoroughbred geldings (7.4 ± 0.6 yr of age; mean ± SEM) were fed 16 g of calcium butyrate (CB) or an equivalent amount of carrier (CON) daily for 30 d in a crossover design. Middle gluteal muscle biopsies were collected before and after the feeding trial for immunohistochemical determination of fiber type, and RNA and protein isolation. After 30 d, CB increased (P < 0.05) the percentage of type IIA fibers and tended (P = 0.13) to reduce the numbers of type IIX fibers in comparison to control (CON). No changes (P > 0.05) in type I, IIA, or IIX fiber size were observed in response to CB. No differences (P > 0.05) were noted in the abundance of succinate dehydrogenase (SDH) protein or activity between horses receiving CB or CON. Myogenin mRNA abundance was unaffected (P > 0.05) by 30 d of CB supplementation. The increase in type IIA fibers in the absence of altered mitochondrial SDH enzymatic activity suggests that CB affects myosin ATPase expression independent of altered metabolism.

The largest tissue in the body, skeletal muscle, is a heterogeneous mix of fibers that are categorized based on their primary source of energy production and speed of contraction. Evidence suggests that Thoroughbred horses with a greater percentage of type IIA, fast-twitch, oxidative fibers are more successful than those with fewer. Pigs fed a diet supplemented with butyrate contained a greater percentage of oxidative muscle fibers. This study examined the ability of calcium butyrate (CB), a short-chain fatty acid, to alter muscle fiber composition in horses. Adult Thoroughbred geldings were supplemented with a placebo or CB for 30 d, and gluteus medius muscle biopsies were retrieved and analyzed for fiber type, myogenin expression, and succinate dehydrogenase (SDH) activity. Results demonstrate a small increase in the percentage of type IIA fibers without a change in SDH activity, a marker of oxidative metabolism. Myogenin expression remained unaffected by CB supplementation. These efforts underscore the need for further research to validate improved exercise performance in response to CB supplementation and identify a mechanism of action for the fatty acid in the equine skeletal muscle.

Compound Heterozygous Myosin 5B (Myo5b) Mutation with Early Onset Progressive Cholestasis and No Intestinal Failure.

Background: Exome sequencing studies have recently identified novel genes implicated in normal or low GGT pediatric cholestasis including myosin 5B (MYO5B). Case report: We identified novel compound heterozygote mutations in exon 14 and exon 19 of the MYO5B gene in an 18-month-old Indian child with history of fluctuating jaundice and severe pruritus. His liver biopsy showed portal and perivenular fibrosis with focal bridging septa and mild activity. He is currently on UDCA, cholestyramine and vitamin supplements. There is no history of diarrhea. His asymptomatic mother showed heterozygous mutation in exon 19 of the MYO5B gene and his asymptomatic father showed heterozygous mutation in exon 14 of the MYO5B gene. Conclusion: Our report confirms that patients with compound heterozygote mutations in MYO5B develop progressive cholestasis with no intestinal disease.

Molecular insights into MYO3A kinase domain variants explain variability in both severity and progression of DFNB30 hearing impairment.

Hereditary hearing impairment (HI) is a common disease with the highest incidence among sensory defects. Several genes have been identified to affect stereocilia structure causing HI, including the unconventional myosin3A. Interestingly, we noticed that variants in MYO3A gene have been previously found to cause variable HI onset and severity. Using clinical exome sequencing, we identified a novel pathogenic variant p.(Lys50Arg) in the MYO3A kinase domain (MYO3A-KD). Previous in vitro studies supported its damaging effect as a 'kinase-dead' mutant. We further analyzed this variation through molecular dynamics which predicts that changes in flexibility of MYO3A structure would influence the protein-ATP binding properties. This Lys50Arg mutation segregated with congenital profound non-syndromic HI. To better investigate this variability, we collected previously identified MYO3A-KDs variants, p.(Tyr129Cys), p.(His142Gln) and p.(Pro189Thr), and built both wild type and mutant 3 D MYO3A-KD models to assess their impact on the protein structure and function. Our results suggest that KD mutations could either cause a congenital profound form of HI, when particularly affecting the kinase activity and preventing the auto-phosphorylation of the motor, or a late onset and progressive form, when partially or completely inactivating the MYO3A protein. In conclusion, we report a novel pathogenic variant affecting the ATP-binding site within the MYO3A-KD causing congenital profound HI. Through computational approaches we provide a deeper understanding on the correlation between the effects of MYO3A-KD mutations and the variable hearing phenotypes. To the best of our knowledge this is the first study to correlate mutations' genotypes with the variable phenotypes of DFNB30.Communicated by Ramaswamy H. Sarma.

Modified citrus pectin prevents isoproterenol-induced cardiac hypertrophy associated with p38 signalling and TLR4/JAK/STAT3 pathway.

Modified citrus pectin (MCP) is a specific inhibitor of galectin-3 (Gal-3) that is regarded as a new biomarker of cardiac hypertrophy, but its effect is unclear. The aim of this study is to investigate the role and mechanism of MCP in isoproterenol (ISO)-induced cardiac hypertrophy. Rats were injected with ISO to induce cardiac hypertrophy and treated with MCP. Cardiac function was detected by ECG and echocardiography. Pathomorphological changes were evaluated by the haematoxylin eosin (H&E) and wheat germ agglutinin (WGA) staining. The hypertrophy-related genes for atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and ß-myosin heavy chain (ß-MHC), and the associated signal molecules were analysed by qRT-PCR and western blotting. The results show that MCP prevented cardiac hypertrophy and ameliorated cardiac dysfunction and structural disorder. MCP also decreased the levels of ANP, BNP, and ß-MHC and inhibited the expression of Gal-3 and Toll-like receptor 4 (TLR4). Additionally, MCP blocked the phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3), but it promoted the phosphorylation of p38. Thus, MCP prevented ISO-induced cardiac hypertrophy by activating p38 signalling and inhibiting the Gal-3/TLR4/JAK2/STAT3 pathway.

Activation of IGF-1 pathway and suppression of atrophy related genes are involved in Epimedium extract (icariin) promoted C2C12 myotube hypertrophy.

The regenerative effect of Epimedium and its major bioactive flavonoid icariin (ICA) have been documented in traditional medicine, but their effect on sarcopenia has not been evaluated. The aim of this study was to investigate the effects of Epimedium extract (EE) on skeletal muscle as represented by differentiated C2C12 cells. Here we demonstrated that EE and ICA stimulated C2C12 myotube hypertrophy by activating several, including IGF-1 signal pathways. C2C12 myotube hypertrophy was demonstrated by enlarged myotube and increased myosin heavy chains (MyHCs). In similar to IGF-1, EE/ICA activated key components of the IGF-1 signal pathway, including IGF-1 receptor. Pre-treatment with IGF-1 signal pathway specific inhibitors such as picropodophyllin, LY294002, and rapamycin attenuated EE induced myotube hypertrophy and MyHC isoform overexpression. In a different way, EE induced MHyC-S overexpression can be blocked by AMPK, but not by mTOR inhibitor. On the level of transcription, EE suppressed myostatin and MRF4 expression, but did not suppress atrogenes MAFbx and MuRF1 like IGF-1 did. Differential regulation of MyHC isoform and atrogenes is probably due to inequivalent AKT and AMPK phosphorylation induced by EE and IGF-1. These findings suggest that EE/ICA stimulates pathways partially overlapping with IGF-1 signaling pathway to promote myotube hypertrophy.

Creatine improves the flesh quality of Pacific white shrimp (Litopenaeus vannamei) reared in freshwater.

Creatine improves flesh quality on mammalian but studies on crustaceans are scarce. In the present study, diets with six levels of creatine (1.23, 2.58, 5.12, 8.28, 14.12, 24.49 g kg-1 diet) were hand-fed to juvenile Litopenaeus vannamei (IBW: 1.50 ± 0.02 g) reared in freshwater for 46 days. Results showed creatine supplementation did not affect the growth performance (FBW: 17.04 ± 1.28 g) or the content of guanidinoacetic acid in muscle and hepatopancreas whereas significantly increased muscular creatine content. Diet with 8.28 g kg-1 creatine significantly increased muscular hardness and chewiness by decreasing myofiber diameter and increasing myofiber density. Additionally, creatine downregulated the mRNA expression of fast sMyHC1, sMyHC2, sMyHC6a and upregulated slow sMyHC5 and sMyHC15 mRNA expression. Muscular protein, collagen, total amino acid and flavor amino acid contents increased with creatine supplementation. In conclusion, the diet with 8.28 g kg-1 creatine improved the flesh quality of L. vannamei.

Effects of dietary ferulic acid supplementation on growth performance and skeletal muscle fiber type conversion in weaned piglets.

BACKGROUND: Ferulic acid (FA) is a common polyphenolic compound. The purpose of this study was to explore the effect of dietary FA supplementation on growth performance and muscle fiber type conversion in weaned piglets. In this study, eighteen 21-day-old DLY (Duroc × Landrace × Yorkshire) weaned piglets were randomly divided into control, 0.05% FA, and 0.45% FA groups. RESULTS: Our study showed that dietary FA supplementation had no effect on growth performance, but it could upregulate the expression of slow myosin heavy chain (MyHC) protein, increase the activities of succinic dehydrogenase and malate dehydrogenase, and downregulate the expression of fast MyHC protein. Dietary FA supplementation also increased the expression levels of phosphorylated AMP-activated protein kinase, sirtuin 1 (Sirt1), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), myocyte enhancer factor 2C, and troponin I-SS, increased the proportion of slow-twitch fiber, and decreased the proportion of fast-twitch fiber. In addition, our results showed that dietary FA supplementation increased the messenger RNA abundance of mitochondrial nuclear transcription genes, including ATP synthase membrane subunit c locus 1, cytochrome oxidase subunit 1, nuclear respiratory factor 1, mitochondrial transcription factor A, mitochondrial transcription factor B1, and cytochrome c. CONCLUSION: We provided the first evidence that FA could promote muscle fiber type conversion from fast-twitch to slow-twitch via the Sirt1/AMP-activated protein kinase/PGC-1α signaling pathway and could improve the mitochondrial function in weaned piglets. This means that FA can be used as a dietary supplement to improve the quality of pork. © 2021 Society of Chemical Industry.

Deciphering the effective combinatorial components from Si-Miao-Yong-An decoction regarding the intervention on myocardial hypertrophy.

ETHNOPHARMACOLOGICAL RELEVANCE: Si-Miao-Yong-An decoction (SMYAD), a classical traditional Chinese medicine (TCM) formula, has been used to treat various cardiovascular diseases in clinics. AIM OF THE STUDY: The aim of this study is to investigate the effective combinatorial components from SMYAD and its mechanism regarding the intervention on myocardial hypertrophy. MATERIALS AND METHODS: SMYAD constituents absorbed in rat plasma and heart were identified using UHPLC Q-Exactive-Orbitrap MS/MS. The identified constituents in SMYAD were further analyzed using ADMET (absorption, distribution, metabolism, excretion and toxicity) prediction and molecular docking. The effective constituents were identified using isoproterenol (ISO)-induced H9c2 cardiomyocyte hypertrophy, and neochlorogenic acid (NCA), chlorogenic acid (CA), cryptochlorogenic acid (CCA), isochlorogenic acid C (ICAC), angoroside C (AGDC), isochlorogenic acid A (ICAA), sweroside (SRD), and harpagide (HPD) in SMYAD extract were quantified by HPLC for compatibility. Finally, anti-hypertrophic activities of candidate effective combinatorial components, which were prepared according to the determined molar concentration ratio of effective constituents using reference substance solution, were analyzed using immunofluorescence staining and Quantitative real-time PCR. The expression levels of PI3Kα, p-ERK, p-Akt, Akt, p-mTOR, mTOR and HIF-1α were measured using Western blot. RESULTS: 32 prototypes of SMYAD were identified from plasma and heart tissue of rat. Combining with ADMET prediction, 31 dominant constituents were focused. Based on HIF-1 pathway identified in preliminary result, 17 targets were focused, which were used to dock with 31 constituents. 27 constituents were therefore hit as the potential effective constituents of SMYAD in inhibiting myocardial hypertrophy. Bioactivity evaluation showed that NCA, CA, CCA, ICAC, AGDC, ICAA, SRD, and HPD significantly inhibited the increase of H9c2 cell surface area induced by ISO. Except for ICAA and AGDC, the remaining 6 effective constituents, showing a certain inhibitory effect on ISO-induced ANP mRNA overexpression at high and low concentrations, participated in compatibility based on the molar concentration ratio determined by HPLC. Effective combinatorial components composed of the 6 effective constituents (effective combinatorial components ABC) showed significant inhibitory effect on the increase of cell surface area, and the overexpression of ANP and ß-MHC mRNA in H9c2 cells induced by ISO. Moreover, effective combinatorial components ABC significantly inhibited the protein overexpressions of p-Akt, p-mTOR and HIF-1α. Based on the results, we put forward the strategy of "Focusing constituents" and "Focusing targets" for the effective constituents research of TCM formula. CONCLUSION: Effective combinatorial components ABC composed of NCA, CA, CCA, ICAC, SRD and HPD from SMYAD inhibited ISO-induced cardiomyocyte hypertrophy and down-regulated expression of ANP and ß-MHC mRNA through the inactivation of Akt/mTOR/HIF-1α pathway.

Magnoflorine prevent the skeletal muscle atrophy via Akt/mTOR/FoxO signal pathway and increase slow-MyHC production in streptozotocin-induced diabetic rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Tinospora cordifolia (TC) is being used as a blood purifier in Ayurveda since ancient time. It is a very popular immunomodulator and holds anti-inflammatory and anti-oxidative potential, hence anti-aging properties. Therefore, it is also known as 'Amrita' in Ayurveda and is widely used to treat diabetes mellitus type II (T2DM) and its secondary complications; however, its underlying mechanism was not expedited to date. AIM-: To explore the in vivo therapeutic efficiency and mechanism of action of TC and its secondary constitute magnoflorine on the skeletal muscle atrophy in the rat model of T2DM. METHOD: Animal model of T2DM was developed using streptozotocin (STZ) injection followed by intervention with TC, metformin, and magnoflorine for three weeks. Confirmation of T2DM and abrogation of atrophic markers and possible mechanisms on supplementation of TC and magnoflorine were explored using histology, bio-assays, Western blotting, and q-PCR. RESULT: TC and Magnoflorine supplementations significantly (p ≤ 0.05) decreased the fasting blood glucose (FBG) levels in T2DM rats. Both treatments prevented the lean body, individual skeletal muscle mass, and myotubes diameter loss (p ≤ 0.05). Magnoflorine significantly reduced the degradation of the protein indicated by biochemical markers of atrophy i.e. decreased serum creatine kinase (CK) levels and increased myosin heavy chain-ß (MyHC-ß) levels in muscles. Q-PCR and western blotting supported the findings that magnoflorine significantly increased the mRNA and protein abundances (~3 fold) of MyHC-ß.TC and magnoflorine efficiently decreased the expression of ubiquitin-proteasomal E3-ligases (Fn-14/TWEAK, MuRF1, and Atrogin 1), autophagy (Bcl-2/LC3B), and caspase related genes along with calpains activities in T2DM rats. Both TC and magnoflorine also increased the activity of superoxide dismutase, GSH-Px, decreased the activities of ß-glucuronidase, LPO, and prevented any alteration in the catalase activity. In contrast, magnoflorine increased expression of TNF-α and IL-6 whereas TC and metformin efficiently decreased the levels of these pro-inflammatory cytokines (p ≤ 0.05). However, magnoflorine was found to increase phosphorylation of Akt more efficiently than TC and metformin. CONCLUSION: TC, and magnoflorine are found to be effective to control fasting blood glucose levels significantly in T2DM rats. It also promoted the Akt phosphorylation, suppressed autophagy and proteolysis that might be related to blood glucose-lowering efficacy of magnoflorine and TC. However, increased muscle weight, specifically of the soleus muscle, expression of IL-6, and slow MyHC indicated the increased myogenesis in response to magnoflorine and independent from its hypoglycemic activity.

Beneficial Effects of a Mixture of Algae and Extra Virgin Olive Oils on the Age-Induced Alterations of Rodent Skeletal Muscle: Role of HDAC-4.

Aging is associated with a progressive decline in skeletal muscle mass, strength and function (sarcopenia). We have investigated whether a mixture of algae oil (25%) and extra virgin olive oil (75%) could exert beneficial effects on sarcopenia. Young (3 months) and old (24 months) male Wistar rats were treated with vehicle or with the oil mixture (OM) (2.5 mL/kg) for 21 days. Aging decreased gastrocnemius weight, total protein, and myosin heavy chain mRNA. Treatment with the OM prevented these effects. Concomitantly, OM administration decreased the inflammatory state in muscle; it prevented the increase of pro-inflammatory interleukin-6 (IL-6) and the decrease in anti-inflammatory interleukin-10 (IL-10) in aged rats. The OM was not able to prevent aging-induced alterations in either the insulin-like growth factor I/protein kinase B (IGF-I/Akt) pathway or in the increased expression of atrogenes in the gastrocnemius. However, the OM prevented decreased autophagy activity (ratio protein 1A/1B-light chain 3 (LC3b) II/I) induced by aging and increased expression of factors related with muscle senescence such as histone deacetylase 4 (HDAC-4), myogenin, and IGF-I binding protein 5 (IGFBP-5). These data suggest that the beneficial effects of the OM on muscle can be secondary to its anti-inflammatory effect and to the normalization of HDAC-4 and myogenin levels, making this treatment an alternative therapeutic tool for sarcopenia.

Preventive Effects of Schisandrin A, A Bioactive Component of Schisandra chinensis, on Dexamethasone-Induced Muscle Atrophy.

Muscle wasting is caused by various factors, such as aging, cancer, diabetes, and chronic kidney disease, and significantly decreases the quality of life. However, therapeutic interventions for muscle atrophy have not yet been well-developed. In this study, we investigated the effects of schisandrin A (SNA), a component extracted from the fruits of Schisandra chinensis, on dexamethasone (DEX)-induced muscle atrophy in mice and studied the underlying mechanisms. DEX+SNA-treated mice had significantly increased grip strength, muscle weight, and muscle fiber size compared with DEX+vehicle-treated mice. In addition, SNA treatment significantly reduced the expression of muscle degradation factors such as myostatin, MAFbx (atrogin1), and muscle RING-finger protein-1 (MuRF1) and enhanced the expression of myosin heavy chain (MyHC) compared to the vehicle. In vitro studies using differentiated C2C12 myotubes also showed that SNA treatment decreased the expression of muscle degradation factors induced by dexamethasone and increased protein synthesis and expression of MyHCs by regulation of Akt/FoxO and Akt/70S6K pathways, respectively. These results suggest that SNA reduces protein degradation and increases protein synthesis in the muscle, contributing to the amelioration of dexamethasone-induced muscle atrophy and may be a potential candidate for the prevention and treatment of muscle atrophy.

Corylifol A from Psoralea corylifolia L. Enhances Myogenesis and Alleviates Muscle Atrophy.

Inflammatory conditions caused by cancer, chronic diseases or aging can lead to skeletal muscle atrophy. We identified myogenic compounds from Psoralea corylifolia (PC), a medicinal plant that has been used for the treatment of inflammatory and skin diseases. C2C12 mouse skeletal myoblasts were differentiated in the presence of eight compounds isolated from PC to evaluate their myogenic potential. Among them, corylifol A showed the strongest transactivation of MyoD and increased expression of myogenic markers, such as MyoD, myogenin and myosin heavy chain (MHC). Corylifol A increased the number of multinucleated and MHC-expressing myotubes. We also found that the p38 MAPK signaling pathway is essential for the myogenic action of corylifol A. Atrophic condition was induced by treatment with dexamethasone. Corylifol A protected against dexamethasone-induced myotube loss by increasing the proportion of multinucleated MHC-expressing myotubes compared with dexamethasone-damaged myotubes. Corylifol A reduced the expression of muscle-specific ubiquitin-E3 ligases (MAFbx and MuRF1) and myostatin, while activating Akt. These dual effects of corylifol A, inhibition of catabolic and activation of anabolic pathways, protect myotubes against dexamethasone damage. In summary, corylifol A isolated from P. corylifolia alleviates muscle atrophic condition through activating myoblast differentiation and suppressing muscle degradation in atrophic conditions.

Adipogenic and Myogenic Potentials of Chicken Embryonic Fibroblasts in vitro: Combination of Fatty Acids and Insulin Induces Adipogenesis.

The regulation of adipocyte differentiation is an important factor for production efficiency and meat quality in the poultry industry. The purpose of this study was to develop a new in vitro model of adipogenic differentiation of chicken embryonic fibroblasts (CEF). In this study, CEF were isolated at embryonic day (E) 5, and adipogenic differentiation was induced with supplementation of fatty acids (FA) and/or insulin (Ins) for 48 h. Oil-Red-O staining showed that lipid accumulation in E5 CEF was greater when supplemented with a combination of FA and Ins (FI) than other treatment groups (p < 0.05). Genes involved in differentiation of preadipocytes, fatty acid transport, and triacylglycerol synthesis were upregulated in the FI group compared to all other treatment groups (p < 0.01). Under myogenic media, the E5 CEF formed myotubes and expressed myogenic markers, myosin heavy chain (MHC), and myogenin (MyoG), suggesting myogenic potential of E5 CEF. To determine the permissive age window for adipogenic differentiation of CEF, E5, E6, and E7 CEF were induced for adipogenesis with FI treatment in 1%, 5%, or 10% chicken serum (CS). Among all embryonic ages, E5 with 10% CS showed the most lipid accumulation and the least myotube formation with the lowest expression of MHC and MyoG. These data indicate both adipogenic and myogenic potentials of E5 CEF, providing a new in vitro model for a better understanding of the processes of adipogenic and myogenic differentiation in chickens.

The molecular effects of electrical stimulation on the muscle components of the urethra of female rats after trauma by vaginal distention.

AIMS: To evaluate the expression of genes and proteins related to the urethral muscles of female rats after trauma by vaginal distention (VD) and after electrical stimulation therapy (EST). METHODS: We compared the urethras of four groups of 20 animals each: control without trauma (C), 7 (recent-trauma) and 30 days (late-trauma) post-VD, and VD-treated with EST. We evaluated the expression of myogenic regulatory factors MYOD1 and myogenin (MYOG); skeletal muscle myosin heavy chain 1, 2, and 3 (MYH1, MYH2, and MYH3); smooth muscle MYH11; and myosin light chain 9 (MYL9). We used real-time quantitative polymerase chain reaction, Western blot analysis, and immunohistochemistry. RESULTS: MYOD1 and MYOG genes were overexpressed in the recent-trauma group compared with the other groups (P < .05). MYH1 and MYH3 genes were upregulated in the recent-trauma group compared with the control and EST groups (P < .05). The MYH2 gene was overexpressed in the late-trauma group (P < .05), while the MYH2 protein was significantly increased in the EST group compared with control, recent-trauma and late-trauma groups by 5-, 3-, and 2.7-fold change, respectively (P < .05). MYL9 and MYH11 messenger RNA were overexpressed in both trauma groups compared with control and EST groups (P < .05). MYH11 protein was not different among the study groups (P > .05). CONCLUSIONS: EST enhances the recovery of the damaged urethral tissue of rats mainly by acting on the striated-muscle components. The MYH2 pathway underlies the positive effects of EST in the external urethral sphincter.

YQWY decoction reverses cardiac hypertrophy induced by TAC through inhibiting GATA4 phosphorylation and MAPKs.

To investigate the effect of Yiqi Wenyang (YQWY) decoction on reversing cardiac hypertrophy induced by the transverse aortic constriction (TAC). Wistar rats aged 7-8 weeks were subjected to TAC surgery and then randomly divided into 4 groups (n = 5/group): Sham group, TAC group, low-dose group and high dose group. After 16-week intragastric administration of YQWY decoction, the effect of YQWY decoction on alleviating cardiomyocyte hypertrophy was examined by transthoracic echocardiography (TTE), hematoxylin/eosin (HE), wheat germ agglutinin (WGA) staining, enzyme linked immunosorbent assay (ELISA), Western blot (WB), immunohistochemistry (IHC) and immunofluorescence (IF), respectively. The results showed significant differences in left ventricle volume-diastole/systole (LV Vol d/s), N-terminal pro-B-type brain natriuretic peptide (NT-proBNP) (P < 0.01), Ejection Fraction (EF), LV mass and fractional shortening (FS) (P < 0.05) between YQWY-treated group and TAC group. HE and WGA staining showed that treatment with YQWY decoction dramatically prevented TAC-induced cardiomycyte hypertrophy. Moreover, the results of WB, IHC and IF indicated that administration of YQWY could suppress the expressions of cardiac hypertrophic markers, which included the atrial natriuretic peptide (ANP), BNP and myosin heavy chain 7 (MYH7) (P < 0.05) and inhibit phosphorylation of GATA binding protein 4 (P-GATA4) (P < 0.05), phosphorylation of extracellular signal-regulated kinase (P-ERK) (P < 0.05), phosphorylation of P38 mitogen activated protein kinase (P-P38) (P < 0.05) and phosphorylation of c-Jun N-terminal kinase (P-JNK) (P < 0.05). Thus, we concluded that YQWY decoction suppressed cardiomyocyte hypertrophy and reversed the impaired heart function, and the curative effects of YQWY decoction were associated with the decreased phosphorylation of GATA4 and mitogen activated protein kinases (MAPKs), as well as the reduced expression of the downstream targets of GATA4, including ANP, BNP, and MYH7.

Tripeptide Arg-Gly-Asp (RGD) modifies the molecular mechanical properties of the non-muscle myosin IIA in human bone marrow-derived myofibroblasts seeded in a collagen scaffold.

Mesenchymal stem cells (MSCs) were obtained from human bone marrow and amplified in cultures supplemented with human platelet lysate in order to generate myofibroblasts. When MSCs were seeded in solid collagen scaffolds, they differentiated into myofibroblasts that were observed to strongly bind to the substrate, forming a 3D cell scaffold network that developed tension and shortening after KCl stimulation. Moreover, MSC-laden scaffolds recapitulated the Frank-Starling mechanism so that active tension increased in response to increases in the initial length of the contractile system. This constituted a bioengineering tissue that exhibited the contractile properties observed in both striated and smooth muscles. By using the A. F. Huxley formalism, we determined the myosin crossbridge (CB) kinetics of attachment (f1) and detachment (g1 and g2), maximum myosin ATPase activity, molar myosin concentration, unitary CB force and maximum CB efficiency. CB kinetics were dramatically slow, characterizing the non-muscle myosin type IIA (NMMIIA) present in myofibroblasts. When MSCs were seeded in solid collagen scaffolds functionalized with Arg-Gly-Asp (RGD), contractility increased and CB kinetics were modified, whereas the unitary NMMIIA-CB force and maximum CB efficiency did not change. In conclusion, we provided a non-muscle bioengineering tissue whose molecular mechanical characteristics of NMMIIA were very close to those of a non-muscle contractile tissue such as the human placenta.