IGF-1 and myostatin-mediated co-regulation in skeletal muscle and bone of Daurian ground squirrels (Spermophilus dauricus) during different hibernation stages.

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 GSK3ß in the VM muscle showed no obvious differences among the different groups. ß-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 GSK3ß 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.

Association of Myostatin With Complications and Cognition in Lung Cancer Patients With Sarcopenia.

INTRODUCTION: 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.

Fibroblast growth-factor 23-Klotho axis is associated with systemic inflammation and myokine profile in children with chronic kidney disease.

BACKGROUND: Chronic kidney disease is linked to a disturbed fibroblast growth factor-23 (FGF23)-Klotho axis and an imbalance between myostatin and insulin-like growth factor-1 (IGF-1) expression. This cross-sectional study investigates the association of the FGF23-Klotho axis and myokine profile with serum interleukin-6 (IL-6) and their interactions in pediatric patients. METHODS: Serum calcium, phosphorus, 25-hydroxyvitamin D, parathormone, c-terminal FGF23, a-Klotho, myostatin, follistatin, IGF-1, and IL-6 were measured in 53 patients with GFR < 60 ml/min/1,73m2. Myostatin to lean mass (LM) and to IGF-1 ratios were calculated. IL-6 level > 3rd quartile was considered as high. RESULTS: Myostatin, IGF-1, and follistatin were correlated to LM (rs = 0.513, p < 0.001, rs = 0.652, p < 0.001, rs=-0.483, p < 0.001). Myostatin and follistatin were correlated to IGF-1 (rs = 0.340, p = 0.014, rs=-0.385, p = 0.005). Myostatin/LM but not myostatin or myostatin/IGF-1 ratio was significantly higher in CKD 5D patients (p = 0.001,p = 0.844, p = 0.111). Among mineral bone parameters, lnFGF23 was correlated to lnIL-6 (rs = 0.397, p = 0.004) and associated with high IL-6 (OR 1.905, 95% CI 1.023-3.548). Among myokines, myostatin/IGF-1 ratio was correlated to lnIL-6 (rs = 0.395, p = 0.004) and associated with high IL-6 (OR 1.113, 95% CI 1.028-1.205). All associations were adjusted to CKD stage. Myostatin was correlated to lnFGF23 (rs = 0.331, p = 0.025) and myostatin/IGF-1 ratio to lnKlotho (rs=-0.363, p = 0.013), after adjustment for CKD stage, lnIL-6 and other mineral bone parameters. CONCLUSIONS: In pediatric CKD, FGF23 and myostatin/IGF-1 ratio are associated with IL-6, indicating a link between systemic inflammation, mineral bone, and myokine disorders. The correlations between myostatin and FGF23 and between myostatin/IGF-1 and Klotho suggest an interaction between mineral bone and muscle metabolism.

Impact of Disease Severity and Disease-Modifying Therapies on Myostatin Levels in SMA Patients.

Clinical trials with treatments inhibiting myostatin pathways to increase muscle mass are currently ongoing in spinal muscular atrophy. Given evidence of potential myostatin pathway downregulation in Spinal Muscular Atrophy (SMA), restoring sufficient myostatin levels using disease-modifying treatments (DMTs) might arguably be necessary prior to considering myostatin inhibitors as an add-on treatment. This retrospective study assessed pre-treatment myostatin and follistatin levels' correlation with disease severity and explored their alteration by disease-modifying treatment in SMA. We retrospectively collected clinical characteristics, motor scores, and mysotatin and follistatin levels between 2018 and 2020 in 25 Belgian patients with SMA (SMA1 (n = 13), SMA2 (n = 6), SMA 3 (n = 6)) and treated by nusinersen. Data were collected prior to treatment and after 2, 6, 10, 18, and 30 months of treatment. Myostatin levels correlated with patients' age, weight, SMA type, and motor function before treatment initiation. After treatment, we observed correlations between myostatin levels and some motor function scores (i.e., MFM32, HFMSE, 6MWT), but no major effect of nusinersen on myostatin or follistatin levels over time. In conclusion, further research is needed to determine if DMTs can impact myostatin and follistatin levels in SMA, and how this could potentially influence patient selection for ongoing myostatin inhibitor trials.

Myocyte enhancer factor 2 upregulates expression of myostatin promoter in Yesso scallop, Patinopecten yessoensis.

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.

Myostatin's marvels: From muscle regulator to diverse implications in health and disease.

Myostatin, a member of the transforming growth factor-ß superfamily, is a pivotal regulator of skeletal muscle growth in mammals. Its discovery has sparked significant interest due to its multifaceted roles in various physiological processes and its potential therapeutic implications. This review explores the diverse functions of myostatin in skeletal muscle development, maintenance and pathology. We delve into its regulatory mechanisms, including its interaction with other signalling pathways and its modulation by various factors such as microRNAs and mechanical loading. Furthermore, we discuss the therapeutic strategies aimed at targeting myostatin for the treatment of muscle-related disorders, including cachexia, muscular dystrophy and heart failure. Additionally, we examine the impact of myostatin deficiency on craniofacial morphology and bone development, shedding light on its broader implications beyond muscle biology. Through a comprehensive analysis of the literature, this review underscores the importance of further research into myostatin's intricate roles and therapeutic potential in human health and disease.

Transglutaminase-catalyzed covalent.

Nature realizes protein and peptide depots by catalyzing covalent bonds with the extracellular matrix (ECM) of tissues. We are translating this natural blueprint for the sustained delivery of a myostatin-inhibiting peptide (Anti-Myo), resulting in an enzyme depot established from injectable solutions. For that, we fused Anti-Myo to the D-domain of insulin-like growth factor I, a transglutaminase (TG) substrate. TG catalyzed the covalent binding of the D-domain to ECM proteins, such as laminin and fibronectin, on bioengineered ECM and in mice. ECM decorated with Anti-Myo suppressed myostatin activity and pathway activation and reduced the differentiation of preconditioned bone marrow-derived macrophages into osteoclasts in vitro.

A molecular pathway for cancer cachexia-induced muscle atrophy revealed at single-nucleus resolution.

Cancer cachexia is a prevalent and often fatal wasting condition that cannot be fully reversed with nutritional interventions. Muscle atrophy is a central component of the syndrome, but the mechanisms whereby cancer leads to skeletal muscle atrophy are not well understood. We performed single-nucleus multi-omics on skeletal muscles from a mouse model of cancer cachexia and profiled the molecular changes in cachexic muscle. Our results revealed the activation of a denervation-dependent gene program that upregulates the transcription factor myogenin. Further studies showed that a myogenin-myostatin pathway promotes muscle atrophy in response to cancer cachexia. Short hairpin RNA inhibition of myogenin or inhibition of myostatin through overexpression of its endogenous inhibitor follistatin prevented cancer cachexia-induced muscle atrophy in mice. Our findings uncover a molecular basis of muscle atrophy associated with cancer cachexia and highlight potential therapeutic targets for this disorder.

Adipokines and Myokines as Markers of Malnutrition and Sarcopenia in Patients Receiving Kidney Replacement Therapy: An Observational, Cross-Sectional Study.

Chronic kidney disease (CKD) is linked to an elevated risk of malnutrition and sarcopenia, contributing to the intricate network of CKD-related metabolic disorders. Adipokines and myokines are markers and effectors of sarcopenia and nutritional status. The aim of this study was to assess whether the adipokine-myokine signature in patients on kidney replacement therapy could help identify malnutrition and sarcopenia. The study involved three groups: 84 hemodialysis (HD) patients, 44 peritoneal dialysis (PD) patients, and 52 kidney transplant recipients (KTR). Mean age was 56.1 ± 16.3 years. Malnutrition was defined using the 7-Point Subjective Global Assessment (SGA) and the Malnutrition-Inflammation Score (MIS). Sarcopenia was diagnosed based on reduced handgrip strength (HGS) and diminished muscle mass. Concentrations of adipokines and myokines were determined using the enzyme-linked immunosorbent assay (ELISA). 32.8% of all study participants were identified as malnourished and 20.6% had sarcopenia. For malnutrition, assessed using the 7-Point SGA, in ROC analysis albumin (area under the curve (AUC) 0.67 was the best single biomarker identified. In dialysis patients, myostatin (AUC 0.79) and IL-6 (AUC 0.67) had a high discrimination value for sarcopenia, and we were able to develop a prediction model for sarcopenia, including age, albumin, adiponectin, and myostatin levels, with an AUC of 0.806 (95% CI: 0.721-0.891). Adipokines and myokines appear to be useful laboratory markers for assessing malnutrition and sarcopenia. The formula we propose could contribute to a better understanding of sarcopenia and potentially lead to more effective interventions and management strategies for dialysis patients.

Serum myostatin is associated with central-to-peripheral arterial stiffness gradient in healthy adolescents. The MACISTE Study.

BACKGROUND: myostatin is a protein compound structurally related to the TGF-beta protein, which plays a pivotal role in regulating muscle growth and extracellular matrix production. exerts both profibrotic and antihypertrophic effects on vascular smooth muscle cells. Aim of the study was to explore the potential association between serum myostatin levels (sMSTN) and carotid-femoral pulse-wave velocity (cf-PWV), carotid-radial pulse wave velocity (cr-PWV), and their ratio (PWVr), in a cohort of healthy adolescents. METHODS: a cohort of 128 healthy subjects (mean age 17±2 years, 59% male) was randomly selected from participants to the MACISTE (Metabolic And Cardiovascular Investigation at School, TErni) study. sMSTN was assessed utilizing an enzyme-linked immunosorbent assay. PWVs were measured in the supine position using high-fidelity applanation tonometry. RESULTS: The mean cf-PWV was 5.1±0.9 m/s, cr-PWV was 6.9±0.9 m/s, PWVr was 0.75±0.12. PWVr exhibited a linear increase across increasing quartiles of sMSTN (0.71±0.1, 0.74±0.1, 0.7±0.1, 0.77±0.1, p for trend=0.03), whereas the association between sMSTN and each single component of PWVr (cf-PWV, cr-PWV) did not attain statistical significance. Quartiles of sMSTN displayed a positive trend with serum HDL-cholesterol (p=0.01) and a negative one with LDL-cholesterol (p=0.01). In a multivariate linear model, the association between PWVr and sMSTN was independent from SBP values, age, sex, heart rate, BMI, HDL-cholesterol and HOMA Index. CONCLUSIONS: In healthy adolescents, sMSTN showed independent associations with PWVr, a measure of central-to-peripheral arterial stiffness gradient. sMSTN may exert differential effects on the structural and functional properties of the arterial wall.

A comparative study on the expression of myogenic genes, and their effects on performance and meat quality in broiler chicken strains.

The aims of current investigation were to study the growth performance, carcass traits, meat quality and expression profile of Myostatin (MSTN), Insulin-like growth factor-1 (IGF-I), Myogenin (MyoG) and Myogenic regulatory factor 4 (MRF4) genes in three commercial broiler strains including Ross (Ross 308), Cobb (Cobb 500), and Arian in 2023. A total number of 240 one-day-old chicks were reared under an equalized standard management condition for 6 weeks. Performance, organ weights, meat quality and the expression level of the myogenic genes in the pectoral muscle were investigated. The lowest body weight (BW), feed intake, weight gain and highest feed conversion ratio (FCR) was observed for Arian at the end of the study. The meat quality was similar between strains. The IGF-I expression level was significantly higher on 42 days of age in Cobb compared to Ross and Arian. The MRF4 expression level was significantly higher on 28 days of age in Cobb compared to Ross. The MyoG expression level was significantly lower in Arian compared to Cobb on 42 days of age. Furthermore, the MSTN expression level was significantly lower in Cobb compared to Ross and Arian on 42 days of age. The remarkable differences in gene expression levels at the end of the rearing period was supported by higher growth performance and BW of Cobb compared to Ross and Arian strains. In conclusion, the findings of current study could conveniently help assess the performance of these broiler strains under similar rearing condition.

Sarcopenic obesity in patients awaiting liver transplant: Unique challenges for nutritional recommendations.

Sarcopenic obesity increases the risk of mortality in patients with liver disease awaiting liver transplantation and in the post-transplant period. Nutrition recommendations for individuals with sarcopenia differ from recommendations for patients with obesity or sarcopenic obesity. While these nutrition guidelines have been established in non-cirrhotic patients, established guidelines for liver transplant candidates with sarcopenic obesity are lacking. In this paper, we review existing literature on sarcopenic obesity in patients with chronic liver disease and address opportunities to improve nutritional counseling in patients awaiting liver transplantation.

Activin Signaling Pathway Specialization During Embryonic and Skeletal Muscle Development in Rainbow Trout (Oncorhynchus mykiss).

Activin signaling is essential for proper embryonic, skeletal muscle, and reproductive development. Duplication of the pathway in teleost fish has enabled diversification of gene function across the pathway but how gene duplication influences the function of activin signaling in non-mammalian species is poorly understood. Full characterization of activin receptor signaling pathway expression was performed across embryonic development and during early skeletal muscle growth in rainbow trout (RBT, Oncorhynchus mykiss). Rainbow trout are a model salmonid species that have undergone two additional rounds of whole genome duplication. A small number of genes were expressed early in development and most genes increased expression throughout development. There was limited expression of activin Ab in RBT embryos despite these genes exhibiting significantly elevated expression in post-hatch skeletal muscle. CRISPR editing of the activin Aa1 ohnolog and subsequent production of meiotic gynogenetic offspring revealed that biallelic disruption of activin Aa1 did not result in developmental defects, as occurs with knockout of activin A in mammals. The majority of gynogenetic offspring exhibited homozygous activin Aa1 genotypes (wild type, in-frame, or frameshift) derived from the mosaic founder female. The research identifies mechanisms of specialization among the duplicated activin ohnologs across embryonic development and during periods of high muscle growth in larval and juvenile fish. The knowledge gained provides insights into potential viable gene-targeting approaches for engineering the activin receptor signaling pathway and establishes the feasibility of employing meiotic gynogenesis as a tool for producing homozygous F1 genome-edited fish for species with long-generation times, such as salmonids.

Myostatin serum levels depends on age and diet in athletic and no athletic dogs.

Myostatin is a growth factor related to muscular mass atrophy via mTOR pathway inhibition. Mutations in this gene have been correlated with high muscular mass development in different species of mammals, including human and dogs. Different studies have shown that sport practice increases myostatin gene expression. Some of them were conducted in canine breeds selected for different sport practices, including mushing sports. In this study, body weight, muscular mass, and serum levels of myostatin were analysed in different canine breeds, selected, and not selected for sprint and middle-distance racing, and the effect on epidemiological factors was evaluated. Sex, reproductive status, and canine breed affects body weight and muscular mass, being higher in males, and in sled canine breed. Age has an effect in body weight and myostatin serum levels, being lower in elder dogs. Sport practice and type of diet had an effect in muscular mass development but not in myostatin serum levels. Results showed a high positive correlation between muscular mass and body weight but not with myostatin levels. These results suggest that independent-myostatin mechanisms of mTOR pathway regulation could be related to muscular mass development in dogs.

Effects of weight loss rate on myostatin and follistatin dynamics in patients with obesity.

Background: Exercise-induced cytokines involved in controlling body composition include myostatin (MST) and follistatin (FST), both of which are influenced by physical activity. This study investigated changes in body composition and physical activity during a weight loss program, as well as the impact on serum MST and FST levels at various weight loss rates. Methods: A total of 126 patients with obesity who completed a 6-month weight loss program were divided into three groups based on weight loss rate (%): low (< 3%), middle (3-10%), and high (≥10%). The International Physical Activity Questionnaire was used for assessing physical activity, whereas dual X-ray absorptiometry was used to determine body composition. Serum MST and FST levels were measured using the enzyme-linked immunosorbent assay. Results: The middle and high groups showed a significant decrease in percent body fat and a significant increase in percent lean body mass and physical activity. Serum MST levels increased significantly in all three groups, although FST levels reduced significantly only in the middle group. After adjusting for sex and body composition, changes in peak oxygen intake (ß = -0.359) and serum FST levels (ß = -0.461) were identified as independent factors for the change in MST levels in the low group. Sex (ß = -0.420) and changes in MST levels (ß = -0.525) were identified as independent factors for the change in serum FST levels in the low group, whereas in the high group, sitting time (ß = -0.600) during the weight loss program was identified as an independent factor for change in serum FST levels. Conclusion: Serum MST levels in patients with obesity increased significantly following the weight loss program, independent of weight loss rate. In contrast, serum FST levels reduced significantly only in the 3-10% weight loss group. These findings indicate that MST and FST secretion dynamics may fluctuate in response to physical activity, while also reflecting feedback regulation of body composition and metabolism during weight reduction.

Role of Myostatin in Rheumatoid Arthritis: A Review of the Clinical Impact.

Rheumatoid arthritis (RA) is a chronic inflammatory disease that affects synovial joints and that frequently involves extra-articular organs. A multiplicity of interleukins (IL) participates in the pathogenesis of RA, including IL-6, IL-1ß, transforming growth factor-beta (TGF-ß), and tumor necrosis factor (TNF)-α; immune cells such as monocytes, T and B lymphocytes, and macrophages; and auto-antibodies, mainly rheumatoid factor and anti-citrullinated protein antibodies (ACPAs). Skeletal muscle is also involved in RA, with many patients developing muscle wasting and sarcopenia. Several mechanisms are involved in the myopenia observed in RA, and one of them includes the effects of some interleukins and myokines on myocytes. Myostatin is a myokine member of the TGF-ß superfamily; the overproduction of myostatin acts as a negative regulator of growth and differentiates the muscle fibers, limiting their number and size. Recent studies have identified abnormalities in the serum myostatin levels of RA patients, and these have been found to be associated with muscle wasting and other manifestations of severe RA. This review analyzes recent information regarding the relationship between myostatin levels and clinical manifestations of RA and the relevance of myostatin as a therapeutic target for future research.

Alterations in the fillet quality of myostatin-knockout red sea bream Pagrus major: Preliminary insights into nutritional, compositional, and textural properties.

Myostatin (MSTN) is a negative regulator of skeletal muscle growth and a popular target for enhancing the productivity of farmed fish. We previously developed an mstn-knockout breed of the aquaculture fish red sea bream (Pagrus major) using genome editing technology. However, little is known about the effects of mstn disruption on the fillet quality of red sea bream and other fish species. In this study, we used fillets of mstn-deficient red sea bream to evaluate their compositional and textural changes during refrigeration. Compared to the wild type, the mutant fillets exhibited an increase in moisture content and a decrease in drippings, indicating an enhanced water-holding capacity. Furthermore, the mutant fillets showed increased water retention and marginally lower collagen content, resulting in lower breaking force, an index of texture. In conclusion, we demonstrated that mstn disruption alters the compositional and textural properties of red sea bream fillets.

Lost in translation: challenges of current pharmacotherapy for sarcopenia.

A healthy lifespan relies on independent living, in which active skeletal muscle is a critical element. The cost of not recognizing and acting earlier on unhealthy or aging muscle could be detrimental, since muscular weakness is inversely associated with all-cause mortality. Sarcopenia is characterized by a decline in skeletal muscle mass and strength and is associated with aging. Exercise is the only effective therapy to delay sarcopenia development and improve muscle health in older adults. Although numerous interventions have been proposed to reduce sarcopenia, none has yet succeeded in clinical trials. This review evaluates the biological gap between recent clinical trials targeting sarcopenia and the preclinical studies on which they are based, and suggests an alternative approach to bridge the discrepancy.

Research Note: Sexual dimorphic effect of myostatin mutation on fat accumulation in Japanese quail.

As an anti-myogenic factor, the myostatin (MSTN) gene was mainly considered as a genetic marker to improve meat production. Moreover, an additional effect of the MSTN mutation on reducing fat deposition in various farm animals suggested a potential application of the MSTN gene on regulating fat deposition in poultry species. Although increase in muscle mass resulted from muscle hyperplasia in the MSTN mutant quail, cellular mechanism behind the decrease in fat deposition was not investigated in the quail model. In the current study, to investigate sexual dimorphic association between fat deposition and Mstn mutation in quail, leg and abdominal fat pads from 4-month-old male and female quail were histologically analyzed. Interestingly, abdominal and leg fat pad weights were significantly decreased by the MSTN mutation only in female quail, but not in male quail, showing sexual dimorphism in regulating fat deposition by the MSTN mutation in quail. Histological analysis also revealed that fat cell sizes of leg and abdominal fats were significantly reduced only in female groups aligning with the decreased fat pad weights. Sexual dimorphic effect of the MSTN mutation on fat cell hypotrophy and reduced fat pad weights in quail provided an important scientific finding to be considered on the usage of the MSTN gene as a genetic marker to reduce fat deposition in poultry species.

Inflammatory Cytokine-Induced Muscle Atrophy and Weakness Can Be Ameliorated by an Inhibition of TGF-ß-Activated Kinase-1.

Chronic inflammation causes muscle wasting. Because most inflammatory cytokine signals are mediated via TGF-ß-activated kinase-1 (TAK1) activation, inflammatory cytokine-induced muscle wasting may be ameliorated by the inhibition of TAK1 activity. The present study was undertaken to clarify whether TAK1 inhibition can ameliorate inflammation-induced muscle wasting. SKG/Jcl mice as an autoimmune arthritis animal model were treated with a small amount of mannan as an adjuvant to enhance the production of TNF-α and IL-1ß. The increase in these inflammatory cytokines caused a reduction in muscle mass and strength along with an induction of arthritis in SKG/Jcl mice. Those changes in muscle fibers were mediated via the phosphorylation of TAK1, which activated the downstream signaling cascade via NF-κB, p38 MAPK, and ERK pathways, resulting in an increase in myostatin expression. Myostatin then reduced the expression of muscle proteins not only via a reduction in MyoD1 expression but also via an enhancement of Atrogin-1 and Murf1 expression. TAK1 inhibitor, LL-Z1640-2, prevented all the cytokine-induced changes in muscle wasting. Thus, TAK1 inhibition can be a new therapeutic target of not only joint destruction but also muscle wasting induced by inflammatory cytokines.