Myostatin (MSTN) plays an important role in muscle development in animals, especially for mammals and fishes. However, little information has been reported on the regulation of MSTN in marine invertebrates, such as bivalves. In the present study, we cloned the MSTN promoter sequence of Yesso scallop Patinopecten yessoensis, identifying 4 transcription start sites, eleven TATA boxes and one E-box. Additionally, transcription factor binding sites, including myocyte enhancer factor 2 (MEF2) and POU homeodomain protein, were identified. The interaction between the MSTN promoter and MEF2 was analyzed to reveal the transcriptional activity of different fragment sizes of promoters through the dual-luciferase reporter assays. The highest transcriptional activity was found in recombinant plasmids with the most MEF2 binding sites, indicating that this transcription factor upregulates MSTN in Yesso scallop. This study provides new insight into the regulation of muscle growth and development in this species.

OBJECTIVE: To observe the effects of thunder-fire moxibustion on the balance function and musculoskeletal metabolism in female patients of primary osteoporosis (POP) with low muscle mass.
METHODS: Sixty female patients of POP with low muscle mass were randomly divided into an observation group (30 cases, 5 cases dropped out) and a control group (30 cases, 2 cases dropped out). The patients in the control group were treated with oral administration of Caltrate D (1.5 g calcium carbonate + 125 IU vitamin D3), one tablet per day for 12 weeks. In addition to the control treatment, the patients in the observation group were treated with thunder-fire moxibustion at Mingmen (GV 4), Yaoyangguan (GV 3), bilateral Ganshu (BL 18), Shenshu (BL 23), and Dachangshu (BL 25), 30 min per acupoint, once every other day, three times a week, for 12 weeks. Balance function indexes (95% confidence ellipse area of the center of pressure [COP], total displacement, average speed), lumbar pain visual analogue scale (VAS), serum muscle metabolism factors (myostatin [MSTN], peroxisome proliferator-activated receptor γ coactivator-1α [PGC-1α]) and bone metabolism factors (aminoterminal propeptide typeⅠ procollagen [PINP], C-terminal telopeptide of typeⅠcollagen [CTX-Ⅰ]) were compared before and after treatment in both groups.
RESULTS: Compared before treatment, the 95% confidence ellipse area of COP, total displacement, and average speed in the observation group were decreased after treatment (P<0.01), and the above indexes in the observation group were lower than those in the control group (P<0.05). Compared before treatment, the VAS scores in both groups were decreased after treatment (P<0.01), the score in the observation group was lower than that in the control group (P<0.01). Compared before treatment, the serum levels of MSTN, PINP and CTX-Ⅰ in the observation group were reduced after treatment (P<0.01), while the serum level of PGC-1α was increased (P<0.01). The control group showed a decrease in serum level of MSTN (P<0.05). The observation group had lower serum levels of MSTN and PINP (P<0.05) and higher serum level of PGC-1α (P<0.01) compared to the control group.
CONCLUSIONS: The thunder-fire moxibustion can effectively relieve lumbar pain, improve balance function, and regulate musculoskeletal metabolism in female patients of POP with low muscle mass.
目的：观察雷火灸对原发性骨质疏松症（POP）伴低肌肉质量女性患者平衡功能和肌骨代谢水平的影响。方法：将60例POP伴低肌肉质量女性患者随机分为观察组（30例，脱落5例）和对照组（30例，脱落2例）。对照组予钙尔奇D（1.5 g碳酸钙＋125 IU维生素D3）口服，每次1片，每天1次，共治疗12周；观察组在对照组基础上予雷火灸治疗，穴取命门、腰阳关及双侧肝俞、肾俞、大肠俞，每穴艾灸30 min，隔日１次，每周３次，共治疗12周。比较两组患者治疗前后平衡功能指标[足底压力中心（COP）95％置信椭圆面积、总位移、平均速度]及腰部疼痛视觉模拟量表（VAS）评分，检测两组患者治疗前后血清肌肉代谢因子[肌肉生长抑制素（MSTN）、过氧化物酶体增殖物激活受体γ辅激活因子1α（PGC-1α）]和骨代谢因子[Ⅰ型胶原N端前肽（PINP）、Ⅰ型胶原C末端交联肽（CTX-Ⅰ）]水平。结果：治疗后，观察组患者COP 95％置信椭圆面积、总位移、平均速度均较治疗前降低（P<0.01），且观察组低于对照组（P<0.05）；两组患者腰部VAS评分均较治疗前降低（P<0.01），且观察组低于对照组（P<0.01）。治疗后，观察组患者血清MSTN、PINP、CTX-Ⅰ水平较治疗前降低（P<0.01），血清PGC-1α水平较治疗前升高（P<0.01），对照组患者血清MSTN水平降低（P<0.05）；观察组患者血清MSTN、PINP水平低于对照组（P<0.05），血清PGC-1α水平高于对照组（P<0.01）。结论：雷火灸可有效缓解POP伴低肌肉质量女性患者腰部疼痛，改善平衡功能，并调节肌骨代谢水平。.

BACKGROUND: The risk of surgery and postoperative complications increases greatly in frail older patients with sarcopenia. The purpose of this study is to explore the correlation between myostatin (MSTN) levels and cognitive function and postoperative pulmonary complications (PPCs) in older patients undergoing thoracoscopic lobectomy and to determine whether MSTN could be used to predict the risk of postoperative complications and cognitive impairment.
METHODS: A prospective observational study was conducted at the First Affiliated Hospital of Bengbu Medical College, China, between January 2023 and June 2023. The risk factors of PPCs and postoperative cognitive impairment were studied using backward stepwise logistic regression analysis. The independent factors were formed into a linear regression equation to construct a risk score model for each patient. The 122 patients who participated in the study were divided into two groups, a low-level group and a high-level group, based on an MSTN level cut-off; the preoperative MSTN cut-off values was 25.55 ng/mL for cognitive dysfunction and 22.29 ng/mL for PPCs. The PPCs and cognitive function of the groups were compared.
RESULTS: Preoperative MSTN was confirmed as a risk factor for postoperative cognitive dysfunction and PPCs. After surgery, the proportion of patients with cognitive impairment in the high-level group was significantly higher than in the low-level group (P < 0.001). In the high-level group, the incidence of respiratory tract infections was 17.9% higher (P = 0.021), hypoxaemia was 20.5% higher (P = 0.001) and respiratory failure was 14.4% higher (P = 0.012) than in the low-level group. In addition, a high level of MSTN increased the length of hospital stay (P < 0.001) and decreased the Barthel Index score (P < 0.001).
CONCLUSIONS: The study findings suggest that MSTN could be used as an index to predict complications and cognitive impairment after thoracoscopic lobectomy in older patients with sarcopenia and to provide evidence for reducing postoperative cognitive impairment and PPCs.

Muscle and bone are cooperatively preserved in Daurian ground squirrels (Spermophilus dauricus) during hibernation. As such, we hypothesized that IGF-1 and myostatin may contribute to musculoskeletal maintenance during this period. Thus, we systematically assessed changes in the protein expression levels of IGF-1 and myostatin, as well as their corresponding downstream targets, in the vastus medialis (VM) muscle and femur in Daurian ground squirrels during different stages. Group differences were determined using one-way analysis of variance (ANOVA). Results indicated that the co-localization levels of IGF-1 and its receptor (IGF-1R) increased by 50% during the pre-hibernation period (PRE) and by 35% during re-entry into torpor (RET) compared to the summer active period (SA). The phosphorylation level of FOXO1 in the VM muscle increased by 50% in the torpor (TOR) group and by 82% in the inter-bout arousal (IBA) group compared to the PRE group. The phosphorylation level of SGK-1 increased by 54% in the IBA group and by 62% in the RET group compared to the SA group. In contrast, the protein expression of IGF-1 and phosphorylation levels of PI3K, Akt, mTOR, and GSK3β in the VM muscle showed no obvious differences among the different groups. β-catenin protein expression was up-regulated by 84% in the RET group compared to the SA group, while the content of IGF-1 protein, correlation coefficients of IGF-1 and IGF-1R, and phosphorylation levels of PI3K, Akt, and GSK3β in the femur showed no significant differences among groups. Regarding myostatin and its downstream targets, myostatin protein expression decreased by 70% in the RET group compared to the SA group, whereas ActRIIB protein expression and Smad2/3 phosphorylation in the VM muscle showed no obvious differences among groups. Furthermore, Smad2/3 phosphorylation decreased by 58% in the TOR group and 53% in the RET group compared to the SA group, whereas ActRIIB protein expression in the femur showed no obvious differences among groups. Overall, the observed changes in IGF-1 and myostatin expression and their downstream targets may be involved in musculoskeletal preservation during hibernation in Daurian ground squirrels.

Tibetan sheep are vital to the ecosystem and livelihood of the Tibetan Plateau; however, traditional breeding methods limit their production and growth. Modern molecular breeding techniques are required to improve these traits. This study identified a single nucleotide polymorphism (SNP) in myostatin (MSTN) and Callipyge in Tibetan sheep. The findings indicated notable associations between MSTN genotypes and growth traits including birth weight (BW), body length (BL), chest width (ChW), and chest circumference (ChC), as well as a particularly strong association with cannon circumference (CaC) at 2 months of age. Conversely, Callipyge polymorphisms did not have a significant impact on Tibetan sheep. Moreover, the analyses revealed a significant association between sex and BW or hip width (HW) at 2 months of age and ChW, ChC, and CaC at 4 months of age. Furthermore, the study\'s results suggested that the genotype of MSTN as a GA was associated with a notable sex effect on BW, while the genotype of Callipyge (CC) showed a significant impact of sex on CaC at 2 months of age. These results indicated that the SNP of MSTN could potentially serve as a molecular marker for early growth traits in Tibetan sheep.

Dynamic metabolic reprogramming occurs at different stages of myogenesis and contributes to the fate determination of skeletal muscle satellite cells (MuSCs). Accumulating evidence suggests that mutations in myostatin (MSTN) have a vital role in regulating muscle energy metabolism. Here, we explored the metabolic reprogramming in MuSCs and myotube cells in MSTN and FGF5 dual-gene edited sheep models prepared previously, and also focused on the metabolic alterations during myogenic differentiation of MuSCs. Our study revealed that the pathways of nucleotide metabolism, pantothenate and CoA biosynthesis were weakened, while the unsaturated fatty acids biosynthesis were strengthened during myogenic differentiation of sheep MuSCs. The MSTN and FGF5 dual-gene editing mainly inhibited nucleotide metabolism and biosynthesis of unsaturated fatty acids in sheep MuSCs, reduced the number of lipid droplets in per satellite cell, and promoted the pentose phosphate pathway, and the interconversion of pentose and glucuronate. The MSTN and FGF5 dual-gene editing also resulted in the inhibition of nucleotide metabolism and TCA cycle pathway in differentiated myotube cells. The differential metabolites we identified can be characterized as biomarkers of different cellular states, and providing a new reference for MSTN and FGF5 dual-gene editing in regulation of muscle development. It may also provide a reference for the development of muscle regeneration drugs targeting biomarkers.

Myostatin (MSTN) has long been recognized as a critical regulator of muscle mass. Recently, there has been increasing interest in its role in metabolism. In our study, we specifically knocked out MSTN in brown adipose tissue (BAT) from mice (MSTNΔUCP1) and found that the mice gained more weight than did controls when fed a high-fat diet, with progressive hepatosteatosis and impaired skeletal muscle activity. RNA-Seq analysis indicated signatures of mitochondrial dysfunction and inflammation in the MSTN-ablated BAT. Further studies demonstrated that Kruppel-like factor 4 (KLF4) was responsible for the metabolic phenotypes observed, whereas fibroblast growth factor 21 (FGF21) contributed to the microenvironment communication between adipocytes and macrophages induced by the loss of MSTN. Moreover, the MSTN/SMAD2/3-p38 signaling pathway mediated the expression of KLF4 and FGF21 in adipocytes. In summary, our findings suggest that brown adipocyte-derived MSTN regulated BAT thermogenesis via autocrine and paracrine effects on adipocytes or macrophages, ultimately regulating systemic energy homeostasis.

The myostatin (MSTN) gene exhibits significant nucleotide sequence variations in sheep, impacting growth characteristics and muscular traits of the body. However, its influence on specific growth traits in some sheep remains to be further elucidated. This study utilized single nucleotide polymorphism sequence analysis to investigate the role of the MSTN gene in meat production performance across four sheep breeds: Charolais sheep, Australian White sheep, crossbreeds of Australian White and Small-tailed Han, and crossbreeds of Charolais and Small-tailed Han. At a SNP locus of the MSTN gene, the C2361T site was identified, with three genotypes detected: CC, CT, and TT, among which CC predominated. Gene substitution effect analysis revealed that replacing C with T could elevate the phenotypic value. Comparative analysis of data from different genotypes within the same breed highlighted the superiority of CC and TT genotypes in phenotypic values, underscoring the significance of specific genotypes in influencing key traits. Contrasting the performance of different genotypes across breeds, Charolais sheep and Charolais Han hybrids demonstrated superiority across multiple indicators, offering valuable insights for breeding new sheep varieties. Analysis of gender effects on growth characteristics indicated that ewes exhibited significantly wider chest, waist, and hip widths compared to rams, while rams displayed better skeletal growth and muscle development. Additionally, the MSTN gene also exerted certain effects on lamb growth characteristics, with the CC genotype closely associated with weight. These findings not only contribute crucial insights for sheep breeding but also pave the way for future research exploring the interaction of this gene with others.

The myostatin (MSTN) gene also regulates the developmental balance of skeletal muscle after birth, and has long been linked to age-related muscle wasting. Many rodent studies have shown a correlation between MSTN and age-related diseases. It is unclear how MSTN and age-associated muscle loss in other animals are related. In this study, we utilized MSTN gene-edited bovine skeletal muscle cells to investigate the mechanisms relating to MSTN and muscle cell senescence. The expression of MSTN was higher in older individuals than in younger individuals. We obtained consecutively passaged senescent cells and performed senescence index assays and transcriptome sequencing. We found that senescence hallmarks and the senescence-associated secretory phenotype (SASP) were decreased in long-term-cultured myostatin inactivated (MT-KO) bovine skeletal muscle cells (bSMCs). Using cell signaling profiling, MSTN was shown to regulate the SASP, predominantly through the cycle GMP-AMP synthase-stimulator of antiviral genes (cGAS-STING) pathway. An in-depth investigation by chromatin immunoprecipitation (ChIP) analysis revealed that MSTN influenced three prime repair exonuclease 1 (TREX1) expression through the SMAD2/3 complex. The downregulation of MSTN contributed to the activation of the MSTN-SMAD2/3-TREX1 signaling axis, influencing the secretion of SASP, and consequently delaying the senescence of bSMCs. This study provided valuable new insight into the role of MSTN in cell senescence in large animals.

Skeletal muscles serve both in movement and as endocrine organs. Myokines secreted by skeletal muscles activate biological functions within muscles and throughout the body via autocrine, paracrine, and/or endocrine pathways. Skeletal muscle atrophy can influence myokine expression and secretion, while myokines can impact the structure and function of skeletal muscles. Regulating the expression and secretion of myokines through the pharmacological approach is a strategy for alleviating skeletal muscle atrophy. Natural products possess complex structures and chemical properties. Previous studies have demonstrated that various natural products exert beneficial effects on skeletal muscle atrophy. This article reviewed the regulatory effects of natural products on myokines and summarized the research progress on skeletal muscle atrophy associated with myokine regulation. The focus is on how small-molecule natural products affect the regulation of interleukin 6 (IL-6), irisin, myostatin, IGF-1, and FGF-21 expression. We contend that the development of small-molecule natural products targeting the regulation of myokines holds promise in combating skeletal muscle atrophy.