Search Results (1,643)

Skeletal muscle, constituting ~40% of body mass, serves as a primary effector for movement and a key metabolic regulator through myokine secretion. Hereditary myopathies, including dystrophinopathies (DMD/BMD), limb–girdle muscular dystrophies (LGMD), and metabolic disorders like Pompe disease, arise from pathogenic mutations in structural, metabolic, or ion channel genes, leading to progressive weakness and multi-organ dysfunction. Gene therapy has emerged as a transformative strategy, leveraging viral and non-viral vectors to deliver therapeutic nucleic acids. Adeno-associated virus (AAV) vectors dominate clinical applications due to their efficient transduction of post-mitotic myofibers and sustained transgene expression. Innovations in AAV engineering, such as capsid modification (chemical conjugation, rational design, directed evolution), self-complementary genomes, and tissue-specific promoters (e.g., MHCK7), enhance muscle tropism while mitigating immunogenicity and off-target effects. Non-viral vectors (liposomes, polymers, exosomes) offer advantages in cargo capacity (delivering full-length dystrophin), biocompatibility, and scalable production but face challenges in transduction efficiency and endosomal escape. Clinically, AAV-based therapies (e.g., Elevidys^® for DMD, Zolgensma^® for SMA) demonstrate functional improvements, though immune responses and hepatotoxicity remain concerns. Future directions focus on AI-driven vector design, hybrid systems (AAV–exosomes), and standardized manufacturing to achieve “single-dose, lifelong cure” paradigms for muscular disorders. Full article

Sarcopenia, the age-related decline in skeletal muscle mass and function, is a growing health concern in aging populations. Nutritional interventions are increasingly recognized for their therapeutic potential; however, molecular biomarkers that reflect their efficacy are limited. To identify nutrition-responsive genes relevant to sarcopenia, we performed transcriptomic profiling of gastrocnemius muscle from mature and middle-aged mice. Aging-associated differentially expressed genes (DEGs) were filtered based on expression levels and correlation with muscle mass. Functional food interventions, including high- and low-molecular-weight collagen hydrolysates and allulose, were applied, and effect scores were calculated to assess transcriptomic responsiveness. Ajuba, a gene involved in cytoskeletal regulation and tissue remodeling, was significantly downregulated in middle-aged mice, consistent with aging-associated muscle decline. Dietary supplementation restored Ajuba expression across all intervention groups, with the strongest effect observed in the high-molecular-weight collagen group. Ajuba expression also showed strong positive correlations with tibialis anterior mass, hindlimb thickness, and muscle-to-fat ratio. Ajuba was identified as a nutritionally modifiable gene with strong associations to muscle phenotype and dietary response. These findings support Ajuba as a transcriptomic biomarker and potential molecular target for precision nutrition strategies aimed at preventing or mitigating sarcopenia. Full article

Background/Objectives: Sarcopenic obesity, defined by the coexistence of excessive fat accumulation and progressive muscle loss, is associated with an increased risk of metabolic dysfunction and physical disability. While 5,7-dimethoxyflavone (DMF), a bioactive flavone derived from Kaempferia parviflora, has demonstrated anti-obesity and muscle-preserving properties, its effects on sarcopenic obesity remain unclear. Methods: Four-week-old male C57BL/6J mice were fed a high-fat diet (HFD) for 6 weeks to induce sarcopenic obesity, followed by 8 weeks of continued HFD with the oral administration of DMF. Muscle function was assessed through grip strength and treadmill running tests, while muscle and fat volumes were measured using micro-CT. Mechanistic analyses were performed using gene expression and Western blot analysis. Results: DMF significantly reduced body weight, fat mass, and adipocyte size while enhancing grip strength, endurance, skeletal muscle mass, and the muscle fiber cross-sectional area. In the gastrocnemius muscle, DMF increased the gene expression of peroxisome proliferator-activated receptor gamma coactivator-1α (Ppargc1a) and its isoform Ppargc1a4, thereby promoting mitochondrial biogenesis. It also improved protein turnover by modulating protein synthesis and degradation via the phosphatidylinositol 3-kinase/protein kinase B/mechanistic target of rapamycin signaling pathway. In subcutaneous and brown adipose tissues, DMF increased mitochondrial DNA content and the expression of thermogenic and beige adipocyte-related genes. These findings suggest that DMF alleviates sarcopenic obesity by improving mitochondrial function and regulating energy metabolism in both skeletal muscle and adipose tissues via PGC-1α-mediated pathways. Thus, DMF represents a promising therapeutic candidate for the integrated management of sarcopenic obesity. Full article

Background/Objectives: Iron deficiency (ID) is a common nutritional deficiency in infancy and early childhood associated with increased risk of infection and increased likelihood of receiving antibiotic intervention. In the context of ID, antibiotics have been shown to exaggerate the growth impairments and negative impacts on metabolic health of ID itself. The objective of this research was to assess the tissue-level impact of antibiotics when provided during ID. Methods: ID was induced in piglets by withholding an iron dextran shot shortly after birth, and iron deficiency was maintained after weaning by providing an iron-deficient diet starting on postnatal day (PD) 25. Half of the ID piglets received a 3-day antibiotic course (ID + Abx) consisting of spectinomycin and gentamicin from PD34-36. The kidney, liver, skeletal muscle, and hippocampal metabolomes, as well as activity of proteins in the mTOR signaling pathway, were assessed on PD43. Results: While ID had minimal impacts on the liver, kidney, and skeletal muscle metabolomes, ID + Abx impaired energy metabolism and increased ketosis and oxidative stress in peripheral tissues. Hippocampal metabolites involved in neurotransmitter synthesis pathways were affected by ID and ID + Abx to a greater extent. Additionally, the activities of several proteins in the mTOR pathway were upregulated in the hippocampi of ID + Abx piglets compared to both ID and control piglets. Abx provided to iron-sufficient piglets had minimal effects on tissue metabolomes and did not alter the activity of proteins in the mTOR pathway. Conclusions: These results highlight that antibiotic treatment in ID alters metabolism in peripheral tissues and the developing hippocampus beyond those induced by ID alone. Considering that infants and children are develop rapidly, the combination of ID and antibiotics may have lasting impacts on neurodevelopment and cognition. Full article

Emery–Dreifuss muscular dystrophy 1 (EDMD1) arises from mutations in EMD. Most EDMD1 patients lack detectable emerin expression. They experience symptoms such as skeletal muscle wasting, joint contractures, and cardiac conduction defects. Currently, physicians rely on treating patient symptoms without addressing the underlying cause—lack of functional emerin protein. Thus, there is a need for therapeutic approaches that restore emerin protein expression to improve patient outcomes. One way would be to deliver emerin mRNA or protein directly to affected tissues to restore tissue homeostasis. Here, we evaluated the utility of lipid nanoparticles (LNPs) to deliver emerin mRNA to diseased cells. LNPs have been studied for decades and have recently been used clinically for vaccination and treatment of a myriad of diseases. Here, we show that the treatment of emerin-null myogenic progenitors with LNPs encapsulating emerin mRNA causes robust emerin protein expression that persists for at least 4 days. The treatment of differentiating emerin-null myogenic progenitors with 2.5 pg/cell emerin LNPs significantly improved their differentiation. The toxicity profiling of emerin mRNA LNP (EMD-LNP) dosing shows little toxicity at the effective dose. These data support the potential use of EMD-LNPs as a viable treatment option and establishes its utility for studying EDMD pathology. Full article

Background/Objectives: Microvascular complications are a major source of disability in type 2 diabetes mellitus (T2DM). We investigated whether body composition indices derived from multifrequency bioelectrical impedance analysis (BIA) independently predict neuropathy, retinopathy, nephropathy, and stroke, and whether they improve risk discrimination beyond the established clinical variables. Methods: In this cross-sectional analytical study (March 2024–February 2025), 124 adults with T2DM ≥ 12 months attending the outpatient diabetes clinic of the Universidad Técnica de Ambato (Ecuador) were enrolled. After an overnight fast and 15 min supine rest, thirteen whole-body BIA metrics including skeletal muscle mass (SMM), intracellular water (ICW), phase angle (PhA), and visceral fat area (VFA) were obtained with a segmental analyzer (InBody S10). Complications were ascertained with standard clinical and laboratory protocols. Principal component analysis (PCA) summarized the correlated BIA measures; multivariable logistic regression (adjusted for age, sex, diabetes duration, HbA1c, BMI, and medication use) generated odds ratios (ORs) per standard deviation (SD). Discrimination was assessed with bootstrapped receiver-operating characteristic curves. Results: The first principal component, driven by SMM, ICW, and PhA, accounted for a median 68% (range 65–72%) of body composition variance across all complications. Each SD increase in SMM lowered the odds of neuropathy (OR 0.54, 95% CI 0.41–0.71) and nephropathy (OR 0.70, 0.53–0.92), whereas VFA raised the risk of neuropathy (OR 1.55, 1.22–1.97) and retinopathy (OR 1.47, 1.14–1.88). PhA protected most strongly against stroke (OR 0.55, 0.37–0.82). Composite models integrating SMM, PhA, and adiposity indices achieved AUCs of 0.79–0.85, outperforming clinical models alone (all ΔAUC ≥ 0.05) and maintaining good calibration (Hosmer–Lemeshow p > 0.20). Optimal probability cut-offs (0.39–0.45) balanced sensitivity (0.74–0.80) and specificity (0.68–0.72). Conclusions: A lean tissue BIA signature (higher SMM, ICW, PhA) confers independent protection against neuropathy, retinopathy, nephropathy, and stroke, whereas visceral adiposity amplifies the risk. Because the assessment is rapid, inexpensive, and operator-independent, routine multifrequency BIA can be embedded into diabetes clinics to triage patients for early specialist referral and to monitor interventions aimed at preserving muscle and reducing visceral fat, thereby enhancing microvascular risk management in T2DM. Full article

Obesity, a major global health concern, is associated with systemic metabolic dysregulation. Spexin, a peptide implicated in appetite control and energy balance, may represent a biomarker and therapeutic target in obesity management. This study aimed to investigate tissue-specific modulation of spexin expression in obese male rats subjected to aerobic exercise and/or metformin treatment. Thirty-six Sprague–Dawley rats were randomly assigned to six groups (n = 6 per group): (i) control, (ii) obese control, (iii) exercise, (iv) metformin, (v) metformin + exercise, and (vi) a decapitation baseline group. Obesity was induced via a 12-week high-calorie diet. Subsequently, interventions were applied over 4 weeks: treadmill running (30 min/day, 5 days/week) and/or metformin (150 mg/kg/day). Post-intervention, body weight significantly decreased in intervention groups (p < 0.001) exercise (−13.7%), metformin (−14.6%), and metformin + exercise (−21.1%) compared to the obese control group. ELISA revealed tissue-specific effects on spexin expression. In skeletal muscle, spexin levels were highest in controls (628 ± 160.5 pg/mL), with a significant reduction in the metformin + exercise group (349 ± 84.7 pg/mL; p = 0.003, Cohen’s d = 2.17). In the liver, the control group showed the highest expression (443 ± 240.8 pg/mL), while metformin + exercise yielded the lowest (254 ± 20.4 pg/mL). In contrast, heart tissue maintained elevated spexin levels across all intervention groups, with the metformin + exercise group nearly matching control levels (617 ± 25.2 vs. 618 ± 53.2 pg/mL). Immunohistochemistry confirmed these patterns, with the highest cardiac histoscore in the metformin + exercise group (2.34 ± 0.09). Hierarchical clustering underscored distinct tissue-specific expression patterns, separating muscle from liver and heart. Collectively, these findings suggest that spexin is differentially regulated by exercise and metformin, with joint effects and complex, tissue-specific modulation. This highlights spexin’s potential as a biomarker and therapeutic target in precision obesity interventions. Full article

In recent years, irisin has garnered significant interest among researchers. It is a myokine released by skeletal muscles during physical exercise. Its expression occurs not only in skeletal muscles but also in other organs such as the liver, kidneys, and lungs, where it fulfills important metabolic and protective functions. Irisin is involved in the regulation of energy homeostasis, promotes the browning of adipose tissue, plays a protective role, and influences the body’s adaptation to physical exercise. In the context of internal organ function, studies suggest its potential role in protecting the kidneys from damage, modulating inflammatory processes in the lungs, and supporting liver regeneration. This literature review focuses on analyzing the therapeutic effects of irisin in these organs in relation to the role of physical exercise. Full article

Circadian rhythms are intrinsic 24 h cycles that regulate metabolic processes across multiple tissues, with skeletal muscle emerging as a central node in this temporal network. Muscle clocks govern gene expression, fuel utilisation, mitochondrial function, and insulin sensitivity, thereby maintaining systemic energy homeostasis. However, circadian misalignment, whether due to behavioural disruption, nutrient excess, or metabolic disease, impairs these rhythms and contributes to insulin resistance, and the development of obesity, and type 2 diabetes mellitus. Notably, the muscle clock remains responsive to non-photic cues, particularly exercise, which can reset and amplify circadian rhythms even in metabolically impaired states. This work synthesises multi-level evidence from rodent models, human trials, and in vitro studies to elucidate the role of skeletal muscle clocks in circadian metabolic health. It explores how exercise entrains the muscle clock via molecular pathways involving AMPK, SIRT1, and PGC-1α, and highlights the time-of-day dependency of these effects. Emerging data demonstrate that optimally timed exercise enhances glucose uptake, mitochondrial biogenesis, and circadian gene expression more effectively than time-agnostic training, especially in individuals with metabolic dysfunction. Finally, findings are integrated from multi-omic approaches that have uncovered dynamic, time-dependent molecular signatures that underpin circadian regulation and its disruption in obesity. These technologies are uncovering biomarkers and signalling nodes that may inform personalised, temporally targeted interventions. By combining mechanistic insights with translational implications, this review positions skeletal muscle clocks as both regulators and therapeutic targets in metabolic disease. It offers a conceptual framework for chrono-exercise strategies and highlights the promise of multi-omics in developing precision chrono-medicine approaches aimed at restoring circadian alignment and improving metabolic health outcomes. Full article

Skeletal muscle atrophy is a critical health issue affecting the quality of life of elderly individuals and patients with chronic diseases. These conditions induce dysregulation of glucocorticoid (GC) secretion. GCs play a critical role in maintaining homeostasis in the stress response and glucose metabolism. However, prolonged exposure to GC is directly linked to muscle atrophy, which is characterized by a reduction in muscle size and weight, particularly affecting fast-twitch muscle fibers. The GC-activated glucocorticoid receptor (GR) decreases protein synthesis and facilitates protein breakdown. Numerous antagonists have been developed to mitigate GC-induced muscle atrophy, including 11β-HSD1 inhibitors and myostatin and activin receptor blockers. However, the clinical trial results have fallen short of the expected efficacy. Recently, several emerging pathways and targets have been identified. For instance, GC-induced sirtuin 6 isoform (SIRT6) expression suppresses AKT/mTORC1 signaling. Lysine-specific demethylase 1 (LSD1) cooperates with the GR for the transcription of atrogenes. The kynurenine pathway and indoleamine 2,3-dioxygenase 1 (IDO-1) also play crucial roles in protein synthesis and energy production in skeletal muscle. Therefore, a deeper understanding of the complexities of GR transactivation and transrepression will provide new strategies for the discovery of novel drugs to overcome the detrimental effects of GCs on muscle tissues. Full article

Insulin-regulated glucose uptake is a central mechanism in maintaining systemic glucose homeostasis, primarily occurring in skeletal muscle and adipose tissue. This process relies on the insulin-stimulated translocation of the glucose transporter, GLUT4, from specialized intracellular compartments, known as GLUT4 storage vesicles (GSVs), to the plasma membrane. Disruption of this pathway is a hallmark of insulin resistance and a key contributor to the pathogenesis of type 2 diabetes. Recent advances have provided critical insights into both the insulin signalling cascades and the complex biogenesis, as well as the trafficking and fusion dynamics of GSVs. This review synthesizes the current understanding of the molecular mechanisms governing GSV mobilization and membrane fusion, highlighting key regulatory nodes that may become dysfunctional in metabolic disease. By elucidating these pathways, we propose new therapeutic avenues targeting GSV trafficking to improve insulin sensitivity and combat type 2 diabetes. Full article

The kallikrein–kinin system and its B1 and B2 receptors are key regulators in metabolic disorders such as obesity, diabetes, and insulin resistance. Obesity, a chronic and multifactorial condition often associated with comorbidities like type 2 diabetes and dyslipidemia, remains poorly understood at the metabolic level. The kinin B2 receptor (B2R) is involved in blood pressure regulation and glucose metabolism, promoting glucose uptake in skeletal muscle via bradykinin. Studies in B2R-KO mice demonstrate that the absence of this receptor predisposes animals to glucose intolerance under a high-fat diet and impairs adaptive thermogenesis, indicating a protective role for B2R in metabolic homeostasis and insulin sensitivity. In contrast, the kinin B1 receptor (B1R) is inducible under pathological conditions and is activated by kinin metabolites. Mouse models lacking B1R exhibit improved metabolic profiles, including protection against high-fat diet-induced obesity and insulin resistance, enhanced energy expenditure, and increased leptin sensitivity. B1R inactivation in adipocytes enhances insulin responsiveness and glucose tolerance, supporting its role in the development of insulin resistance. Moreover, B1R deficiency improves energy metabolism and thermogenic responses to adrenergic and cold stimuli, promoting the activation of brown adipose tissue and the browning of white adipose tissue. Collectively, these findings suggest that B1R and B2R represent promising therapeutic targets for the treatment of metabolic disorders. Full article

Aim: Pacifiers play a critical role in the early stages of craniofacial and palate development during infancy. While they provide comfort and aid in soothing, their use can also have significant impacts on the growth and function of the oral cavity. This study aimed to simulate and predict the behavior of six different types of pacifiers and their functional interaction with the tongue and palate, with the goal of understanding their potential effects on orofacial growth and development. Materials and Methods: Biomechanical analysis using Finite Element Analysis (FEA) mathematical models was employed to evaluate the behavior of six different commercial pacifiers in contact with the palate and tongue. Three-dimensional solid models of the palate and tongue were based on the mathematical framework from a 2007 publication. This allowed for a detailed investigation into how various pacifier designs interact with soft and hard oral tissues, particularly the implications on dental and skeletal development. Results: The findings of this study demonstrate that pacifiers exhibit different interactions with the oral cavity depending on their geometry. Anatomical–functional pacifiers, for instance, tend to exert lateral compressions near the palatine vault, which can influence the hard palate and contribute to changes in craniofacial growth. In contrast, other pacifiers apply compressive forces primarily in the anterior region of the palate, particularly in the premaxilla area. Furthermore, the deformation of the tongue varied significantly across different pacifier types: while some pacifiers caused the tongue to flatten, others allowed it to adapt more favorably by assuming a concave shape. These variations highlight the importance of selecting a pacifier that aligns with the natural development of both soft and hard oral tissues. Conclusions: The results of this study underscore the crucial role of pacifier geometry in shaping both the palate and the tongue. These findings suggest that pacifiers have a significant influence not only on facial bone growth but also on the stimulation of oral functions such as suction and feeding. The geometry of the pacifier affects the soft tissues (tongue and muscles) and hard tissues (palate and jaw) differently, which emphasizes the need for careful selection of pacifiers during infancy. Choosing the right pacifier is essential to avoid potential negative effects on craniofacial development and to ensure that the benefits of proper oral function are maintained. Therefore, healthcare professionals and parents should consider these biomechanical factors when introducing pacifiers to newborns. Full article

Background/Objective: Exertional rhabdomyolysis (ER) is primarily driven by mechanical stress on muscles during strenuous or unaccustomed exercise, often exacerbated by environmental factors like heat and dehydration. While the general cellular pathway involving energy depletion and calcium overload is understood in horse ER models, the underlying mechanisms specific to the ER are not universally known within humans. This study aimed to evaluate whether patients with ER exhibited transcriptional signatures that were significantly different from those of healthy individuals. Methods: This study utilized RNA sequencing on skeletal muscle samples from 19 human patients with ER history, collected at a minimum of six months after the most recent ER event, and eight healthy controls to investigate the transcriptomic landscape of ER. To identify any alterations in biological processes between the case and control groups, functional pathway analyses were conducted. Results: Functional pathway enrichment analyses of differentially expressed genes revealed strong suppression of mitochondrial function. This suppression included the “aerobic electron transport chain” and “oxidative phosphorylation” pathways, indicating impaired energy production. Conversely, there was an upregulation of genes associated with adhesion and extracellular matrix-related pathways, indicating active restoration of muscle function in ER cases. Conclusions: The study demonstrated that muscle tissue exhibited signs of suppressed mitochondrial function and increased extracellular matrix development. Both of these facilitate muscle recovery within several months after an ER episode. Full article

Skeletal muscle regeneration depends on muscle stem cells, which give rise to myoblasts that drive muscle growth, repair, and maintenance. In bats—the only mammals capable of powered flight—these processes must also sustain contractile performance under extreme mechanical and metabolic stress. However, the cellular and molecular mechanisms underlying bat muscle physiology remain largely unknown. To enable mechanistic investigation of these traits, we established the first myoblast cell lines from the pectoralis muscle of Pteronotus mesoamericanus, a highly maneuverable aerial insectivore. Using both spontaneous immortalization and exogenous hTERT/CDK4 gene overexpression, we generated two stable cell lines that retain proliferative capacity and differentiate into contractile myotubes. These cells exhibit frequent spontaneous contractions, suggesting robust functional integrity at the neuromuscular junction. In parallel, we performed transcriptomic and metabolic profiling of native pectoralis tissue in the closely related Pteronotus parnellii to define molecular programs supporting muscle specialization. Gene expression analyses revealed enriched pathways for muscle metabolism, development, and regeneration, highlighting supporting roles in tissue maintenance and repair. Consistent with this profile, the flight muscle is triglyceride-rich, which serves as an important fuel source for energetically demanding processes, including muscle contraction and cellular recovery. Integration of transcriptomic and metabolic data identified three key metabolic modules—glucose utilization, lipid handling, and nutrient signaling—that likely coordinate ATP production and support metabolic flexibility. Together, these complementary tools and datasets provide the first in vitro platform for investigating bat muscle research, enabling direct exploration of muscle regeneration, metabolic resilience, and evolutionary physiology. Full article