Starvation elicits profound metabolic adaptations in skeletal muscle, enabling survival during nutrient scarcity. While global proteomic changes underpinning muscle atrophy have been studied, the role of lysine β-hydroxybutyrylation (Kbhb), a novel metabolite-derived post-translational modification linked to ketone metabolism, remains largely unexplored. In this study, we subjected mice to 72 h of food deprivation and performed integrative quantitative proteomics and Kbhb-modified peptide profiling on gastrocnemius muscle. Starvation induced significant body weight and muscle mass loss, accompanied by increased systemic β-hydroxybutyrate levels and widespread Kbhb modification of muscle proteins. Proteomic analysis revealed extensive downregulation of ribosomal and translation-associated proteins, coupled with upregulation of autophagy and lipid catabolism pathways, highlighting a coordinated shift from anabolic processes to catabolic and oxidative metabolism. Deep Kbhb profiling identified over 7500 modified lysine sites across 2000 proteins, with starvation triggering a global increase in Kbhb on key metabolic enzymes involved in glycolysis, TCA cycle, fatty acid β-oxidation, and amino acid metabolism. Notably, starvation-enhanced Kbhb preferentially targeted evolutionarily conserved lysines proximal to catalytic or cofactor-binding domains, implicating a regulatory role in enzymatic activity modulation. Conversely, Kbhb on structural and contractile proteins was downregulated, suggesting functional reprioritization of muscle physiology during fasting. Our findings uncover lysine β-hydroxybutyrylation as a dynamic, metabolically responsive PTM mediating gastrocnemius muscle adaptation to energy deficiency, expanding the paradigm of potentially metabolite-driven epigenetic and non-epigenetic regulatory mechanisms in muscle metabolism.

ABSTRACT Animal muscle is an intriguing natural material whose mechanical properties arise from sequence‐diverse protein domains, many of which remain unexplored for material design. Among them, Immunoglobulin‐like (Ig) domains act as molecular springs that can unfold and refold repetitively without losing function, dissipating mechanical energy as heat, making them promising building blocks for next‐generation protein‐based materials (PBMs). In this study, we translate these molecular features to the macroscale by fabricating fibers from microbially‐synthesized Ig domains of various muscle proteins. Among them, Filamin‐derived Ig fibers ( M W = 123 kDa) exhibited a unique combination of high tensile strength (412 ± 22 MPa), high toughness (120 ± 17 MJ/m 3 ), remarkable mechanical stability (∼89%) under 90% humidity, high energy damping capacity (∼80%), and complete shape recovery (∼100%) over repeated loading–unloading cycles. Our results further revealed molecular mechanisms underlying these properties: (i) Ig domain hydrophobicity strongly correlates with fiber assembly and tensile strength, (ii) reversible unfolding–refolding of Ig domains enables efficient energy dissipation and self‐recovery, and (iii) hydrogen‐bonding networks within the amorphous matrix regulate humidity‐induced weakening. Together, these findings establish Ig domains as a new class of PBMs combining advantageous mechanical and physical properties, offering a versatile platform for developing advanced materials with tunable performance.

Mechanisms underlying differential utilization of carbohydrates from diverse structures and sources in Nile tilapia (Oreochromis niloticus): Insights from glycolipid metabolism, protein deposition and liver health.

Skeletal muscle (SkM) accounts for 30%-40% of body mass. SkM is required for body movement, energy metabolism, and material metabolism, all of which directly impact human quality of life. This review traces the key medicinal plants used for alleviating skeletal muscle disorders (SkMDs), with a focus on lifestyle modifications and exercise. A comprehensive literature search was conducted using databases such as Google Scholar, Elsevier, Springer Nature, Wiley, PubMed, and EKB. SkMDs are a broad category of conditions that affect the muscles, bones, joints, and connective tissues, resulting in major impairments in movement, function, and quality of life. SkMDs affect more than 1.3 billion people worldwide and are a major cause of disability and economic hardship. Conventional therapy approaches, such as pharmaceutical interventions and surgical procedures, are typically limited by undesirable side effects, extended recovery times, and patient dissatisfaction, especially when focusing only on symptom relief. In response, complementary and alternative medicine, particularly medicinal herbs, has grown in popularity to improve SkMD management. Medicinal plants have a diverse range of pharmacologically active compounds with anti-inflammatory, analgesic, and antioxidant effects, making them promising additions to traditional treatments. Berberine, curcumin, resveratrol, quercetin, (-)-epicatechin, and ginsenosides have been reported to have potential in SkMDs. These compounds exert their effects through multiple mechanisms, such as enhancing muscle protein synthesis, reducing inflammation, and modulating hormones that influence muscle mass. Overall, the study emphasizes the ability of natural supplementation approaches to improve clinical outcomes, improve patient well-being, and provide a more sustainable model for treating SkMDs.

Background: Nutritional interventions to mitigate age/disease-related skeletal muscle attrition are much needed given the growing older population. Beta-hydroxy beta-methylbutyrate (HMB), an endogenous metabolite of the essential amino acid leucine, has anabolic properties in skeletal muscle: acutely stimulating muscle protein synthesis and attenuating muscle protein breakdown. While the role of supplemental HMB on muscle protein turnover is established, mechanistic effects on the muscle transcriptome have not been examined. Methods: Total RNA was extracted from m. vastus lateralis muscle biopsies of young males (n = 14) before and ~2.5 h after oral consumption of ~3 g HMB. Global changes in the muscle transcriptome were assessed via RNA sequencing, and differential expression in genes between fasted and ‘fed’ (HMB) conditions was determined. To identify the functional biology of differentially expressed genes, gene set enrichment and active subnetwork-orientated enrichment analyses was performed. Results: Of 15,982 genes detected, 468 were significantly upregulated and 326 were significantly downregulated in response to HMB. These genes were found to be associated with molecular pathways regulating muscle protein turnover, most notably, JAK-STAT signalling (e.g., STAM), circadian rhythm (e.g., NR1D1, NR1D2, PER2, PER3), TNFα signalling (e.g., TNFRSF1A, CCL2, CXCL2), and protein synthesis (e.g., POLR1A, POLR2A, POLR3A, PIK3RR, SGK1). HMB also regulated the expression of AA transporters, evoking a robust increase in SLC36A1 (PAT1) and SLC7A5 (LAT1). Conclusions: HMB evokes transcriptional events important in the homeostasis of muscle, supporting a role in proteostasis and one akin to protein intake, i.e., upregulation of AA transporters. Future work should further define HMB’s transcriptomic/proteomic effects in ageing/disease and synergy with exercise.

Background: Sarcopenic obesity (SO) is a metabolic myopathy characterized by the coexistence of obesity and decline of muscle mass and function. Obesity-related muscle atrophy represents a central pathological feature of this condition. Polygonati Rhizoma is widely used as a dietary herb with tonic effects in traditional Asian medicine. This study aims to investigate the effects and underlying molecular mechanisms of the water extract of Polygonati Rhizoma (WPR) on obesity-related muscle atrophy. Methods: The effects and potential mechanisms of WPR were explored using an obesity-induced muscle atrophy (OIMA) mouse model, palmitic acid (PA)- or lipopolysaccharide (LPS)-induced myotube atrophy models, and a myogenic differentiation model in C2C12 cells. Results: In OIMA mice, WPR attenuated obesity-related skeletal muscle atrophy and improved muscle strength and endurance. In the gastrocnemius muscle, WPR-treated mice showed lower levels of oxidative stress and inflammation, increased markers of mitochondrial biogenesis, and an improved balance between protein synthesis and degradation. In PA- or LPS-induced myotube atrophy models, WPR treatment suppressed the ubiquitin–proteasome system (UPS)-mediated proteolysis and NFκB/MAPK-related inflammatory signaling. In addition, WPR promoted myogenic differentiation in C2C12 myoblasts, which was associated with regulation of the p38 MAPK/MyoD/Myogenin axis. Conclusions: Our study suggests that WPR exerts a potential mitigating effect on obesity-related muscle atrophy, and this effect may be associated with the modulation of skeletal muscle inflammatory signaling, mitochondrial function, and protein metabolic balance. These findings are exploratory and provide mechanistic clues for future research aimed at developing potential intervention strategies for obesity-related muscle atrophy.

ACTA2 pathogenic variants predispose to thoracic aortic disease, and a subset of variants lead to early onset atherosclerotic cardiovascular disease (ASCVD). The molecular pathway linking misfolded SMA (α-smooth muscle actin) monomers to augmented atherosclerosis-associated smooth muscle cell phenotypic modulation can be modeled in vitro by stably expressing the ACTA2 p.R149C variant in Acta2-/- smooth muscle cells. The Montalcino Aortic Consortium patient registry was used to identify cases with ACTA2 pathogenic/likely pathogenic missense variants. These patients were surveyed, and their medical records were reviewed to identify cases with early onset ASCVD. The variants for these cases, as well as other recurrent ACTA2 missense variants, were individually expressed in Acta2-/- smooth muscle cells, and transcript and protein levels, HSF1 (heat shock factor 1) activation, HMGCR (3-hydroxy-3-methylglutaryl-coenzyme A reductase) expression and activity, cholesteryl ester levels, and downstream smooth muscle cell phenotypic modulation were assessed. Early onset ASCVD included coronary artery disease, peripheral vascular disease, and atherosclerotic plaques identified by imaging in the arch, descending, or abdominal aorta, along with the celiac, iliac, renal, or vertebral arteries. Twelve ACTA2 variants were identified to be associated with early onset ASCVD. Early onset ASCVD was correlated with HSF1 activation (P=0.035), cellular cholesteryl ester levels (P=0.0031), and having one family member with the specific ACTA2 pathogenic variant who had early onset ASCVD (P=0.0001). Assays assessing the molecular mechanism that leads to early onset ASCVD can identify which ACTA2 pathogenic variants will trigger this condition. Ultimately, this information informs precision medical care for individuals with ACTA2 pathogenic variants, with the ultimate goal of preventing thoracic aortic disease and ASCVD.

To observe the effect of electroacupuncture (EA) on the expressions of paired box transcription factor 7 (Pax7), myogenic differentiation antigen (MyoD), myogenin (MyoG) and myosin heavy chain (MyHC) in the multifidus muscle, and CD63, programmed cell death protein 6 interacting protein (Alix) and tumor susceptibility gene 101 (TSG101) proteins in the serum exosomes in rats with lumbar multifidus muscle injury (MFMI), so as to explore the effect of exosomes in acupoint areas on EA improvement of muscular regeneration and repair. Forty male SD rats were randomly divided into normal control, model, EA and EA+exosome inhibitor (EA+inhibitor) groups, with 10 rats in each group. The MFMI model was established by injection of 0.5% bupivacaine (150 μL × 4) into the 4 points of the multifidus muscle along the bilateral lumbar (L)4-L5 spinous processes. EA (2 Hz/10 Hz, 1 mA) was applied to bilateral "Weizhong" (BL40) and "Shenshu" (BL23) for 20 min, once a day for 7 d. For rats of the EA+inhibitor group, exosome inhibitor GW4869 (3 mg/mL, 50 μL/acupoint) was injected into bilateral BL40 and BL23 1 h before each EA intervention. The morphological changes of the multifidus muscle were observed after H.E. staining and Masson staining. The immunoactivity of Pax7 and MyoD was observed by immunohistochemistry. The serum exosomes were extracted and identified by transmission electron microscope (TEM) and nanoparticle tracking analysis (NTA). The expression levels of MyoG and MyHC in the multifidus muscle tissue and CD63, Alix and TSG101 proteins in the serum exosomes were detected by Western blot. Morphological results showed that in the model group, most of the muscle fibers were degenerated and necrotic, a large number of inflammatory cells infiltrated around the muscle fibers and more blue-stained collagen fibers were observed. In the EA group, the morphology of muscle fibers was relatively complete, with more new muscle fibers and reduced inflammatory cells in the injured area, and the collagen fibers were significantly reduced. In the EA+inhibitor group, there were still more muscle fiber destruction and inflammatory cell infiltration, new muscle fibers with uneven diameter and more collagen fibers. Compared with the normal control group, the immunoactivity of Pax7 in the multifidus muscle, the expression of Alix and CD63 proteins in the serum exosomes were significantly increased in the model group (P<0.01, P<0.05, P<0.001). In comparison with the model group, the immunoactivity of Pax7 and MyoD, the expression levels of Alix and TSG101 in the serum exosomes and MyHC and MyoG proteins in the multifidus muscle were considerably up-regulated in the EA group (P<0.01, P<0.05). After local injection of GW4869 at BL40 and BL23, the immunoactivity of Pax7 and MyoD, the protein expression levels of TSG101, CD63, MyHC and MyoG were significantly lower in the EA+inhibitor group than those of the EA group (P<0.01, P<0.05, P<0.001). The results of TEM and NTA showed that the exosomes were successfully extracted. The morphology of the exosomes was typical saucer-like under electron microscope, and the particle size range was concentrated in 70-200 nm. EA of BL40 and BL23 can significantly up-regulate the expressions of Pax7, MyoD, MyoG and MyHC in the injured multifidus muscle, and promote the regeneration and repair of lumbar multifidus muscle, which may be related to its functions in promoting the release of exosomes in the acupoint area.

Dynamic remodeling of intramuscular structural proteins and its impact on abalone muscle quality during post-mortem cold storage.

The blunt snout bream (Megalobrama amblycephala, BSB) is a freshwater economic fish with Chinese characteristics, and its genetic characteristics have unique value for studying fish evolution. The gynogenetic blunt snout bream (GBSB) obtained through distant hybridization between cross-order species, which showed a faster growth rate than the female parent, but its appearance is similar to that of BSB and is difficult to distinguish. Therefore, by comparing the transcriptome sequencing data of BSB and GBSB (SRA number: PRJNA893089, not released yet), we identified 30 SNPs associated with genes related to muscle growth, protein synthesis, and glycolysis that are unique to GBSB. Through multi-sample PCR detection and sequencing analysis, 16 SNPs with stable differences in GBSB and BSB were obtained. The polymorphism analysis of 16 SNP sites showed that 9 SNP sites were polymorphic in GBSB, which could be used to identify GBSB and its female parent, BSB. In addition, the 9 SNP sites are located in the myoz1a (myozenin 1a) gene, which is related to muscle development, and may provide insights for further study of muscle growth regulation. Therefore, this study provides candidate marker resources for GBSB germplasm resource identification and molecular marker-assisted breeding, which is beneficial for improving the efficiency and reliability of selection and breeding work.

The longissimus thoracis (LT) muscle was collected from 12 Mongolian sheep fed either a basal diet (group C) or the basal diet supplemented with 1% l-arginine (group A) for 3 months. l-arginine significantly improved loin muscle area and meat tenderness and enhanced nitric oxide synthase (NOS) enzymatic activity as well as nitric oxide (NO) and NOS gene expression. DIA-based proteomics analysis revealed that the differentially abundant proteins were predominantly enriched in biological functions and metabolic pathways associated with skeletal muscle development and protein metabolism, which showed significant associations with the NO signaling pathways. The results of the PPI network analysis indicated a close interaction among skeletal-muscle-related proteins, which may influence mitochondrial electron transport chain (ETC) function via the NO signaling pathway. In conclusion, supplementing the diet with l-arginine can potentially influence skeletal muscle protein metabolism in Mongolian sheep, particularly affecting muscle contraction and the mitochondrial ETC via NO signaling pathways in LT muscle.

Slaughter is a critical phase in aquaculture that can severely compromise both animal welfare and product quality. Stress responses triggered during this stage may accelerate post-mortem biochemical degradation and promote oxidative damage in fish fillets. Essential oils, known for their antioxidant and anti-inflammatory properties, have been proposed as dietary supplements to help mitigate stress and preserve flesh quality. This study investigated the effects of dietary essential oil supplementation and different slaughter methods, air asphyxia and percussion, on stress biomarkers, oxidative processes, and fillet quality in rainbow trout (Oncorhynchus mykiss), both immediately after slaughter and during frozen storage. Air asphyxiation significantly accelerated ATP degradation, increased lipid and protein oxidation products and caused texture loss in fillets assessed immediately post-slaughter. These effects were markedly less pronounced in percussion-slaughtered fish. Lipid mediators such as 12-HpEPE+15-HpEPE and PGD3 + PGE3 were elevated only in asphyxiated fish, providing potential biomarkers for slaughter-induced stress. Proteomic analysis identified several glycolytic enzymes as highly responsive to air asphyxia. Dietary supplementation with essential oils (0.02%) did not mitigate the immediate physiological stress responses to slaughter and was associated with increased muscle protein oxidation at death. However, during 45 days of frozen storage, fillets from fish fed the supplemented diet exhibited delayed progression of oxidative damage, with improved texture and colour retention, especially under high-stress conditions such as air asphyxia. Although dietary essential oils did not reduce slaughter-induced stress, they proved to be an effective strategy for delaying fish fillet degradation and preserving texture and colour during frozen storage. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

This study investigated the effects of chronic MC-LR exposure (0 μg/L [Control], 1 μg/L [M1], 3 μg/L [M3], 10 μg/L [M10], and 30 μg/L [M30]) on the muscle nutrient composition, meat quality, and muscle proteomic profile of Nile tilapia (Oreochromis niloticus). In the high-dose group (M30), MC-LR exposure compromised the muscle antioxidant status of Nile tilapia, resulting in reduced meat quality, as evidenced by decreased pH value and water-holding capacity, elevated lipid/protein oxidation, and altered texture parameters (shear force and fragmentation index). Proteomic analysis further revealed a downregulation of proteins associated with ribosomes, suggesting an impairment of muscle protein synthesis in the M30 group. Moreover, despite chronic exposure, only low levels of MC-LR accumulated in the muscle tissue, indicating a negligible health risk to consumers. Collectively, these findings offered valuable insights into the impact of environmental MC-LR contamination on fish muscle quality and nutritional value.

Extruded Limnospira platensis with enzyme supplementation shifts the broiler muscle proteome toward enhanced energy metabolism pathways.

The present study evaluated the impact of different stocking densities (SD 10, SD 20, and SD 30 fish m −3 ) on the growth, survival, physiological responses, and economic returns in Amur carp ( Cyprinus carpio haematopterus ) reared in cages for 180 days. The juveniles of Amur carp (12.27 ± 0.31 cm; 35.6 ± 3.16 g) were stocked in galvanised iron cages in triplicate and fed with a floating pellet diet (28% CP, 4% CF) at a gradually reduced rate, from 5 to 3% of body weight per day during the culture period. Growth attributes, including final weight, weight gain, specific growth rate, and feed utilisation indices, declined significantly ( p &amp;lt; 0.05) with increasing stocking density. The survival rate was noticed to be lower at higher densities. Although biomass was higher at SD 30, physiological and biochemical analyses indicated crowding stress, with increased levels of serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), glucose, cortisol, and antioxidant enzymes. Conversely, serum proteins, lipids, thyroid hormones, and immune markers were decreased with density. Poor digestive enzyme activities in terms of amylase and protease were noticed at higher densities, resulting in lower muscle protein content at SD 30. Haematological parameters like red blood cells (RBC), haemoglobin, haematocrit, and platelets increased with density, whilst white blood cells (WBC) remained unchanged. Water quality parameters remained within optimal ranges with minimal variation between inside and outside the cages. The calculated benefit–cost ratio was highest at SD 10 (1.38). Correlation analysis and Integrated Biomarker Response (IBR) indices confirmed density-induced stress, identifying 10 fish/m 3 as the optimal stocking density for Amur carp in tropical Indian reservoir cage culture. These findings support evidence-based management strategies that enhance fish welfare and farmer profitability whilst minimising ecological impacts, thereby promoting responsible aquaculture and advancing sustainable food production in line with global Sustainable Development Goals (SDGs).

Ageing of human myofibres in the Vastus Lateralis muscle: A narrative review.

Postmortem interval (PMI) estimation is a pivotal challenge in forensic science, and skeletal muscle protein degradation has emerged as a promising biochemical tool. In this review, we conducted a comprehensive literature search of PubMed for studies published between 2014 and 2024 using keywords related to PMI estimation and protein/proteomics. Of the 287 results retrieved, 81 were available as free full-text articles, and 17 met the inclusion criteria focusing on skeletal muscle protein. The most used techniques were Western blotting, followed by mass spectrometry and immunohistochemistry. Frequently studied proteins included eEF1A2, desmin, GAPDH, α-actinin, vinculin, α-tubulin, and tropomyosin. Although protein degradation in muscle tissue shows significant potential for PMI estimation, relying on a single protein or a small group of proteins is insufficient due to variability introduced by environmental, individual, and species-specific factors. The study highlights the need for long-term, semi-controlled studies using human tissue, as well as further investigation of new candidate biomarkers and the stability of established markers across diverse PMI ranges and conditions. Comparative studies between animal and human data are vital for understanding species differences and ensuring reliable extrapolation. Moving forward, interdisciplinary and methodologically standardized approaches will be critical for integrating protein-based findings into routine forensic practice and achieving a robust, multifactorial method for PMI estimation.

Longevity of cardiac and skeletal muscle proteins is dependent on tissue and subcellular compartmentation patterns.

Muscle protein metabolism is thought to regulate muscle mass. High-intensity muscle contraction (HiMC) increases muscle protein synthesis (MPS), resulting in muscle hypertrophy. Inhibiting the mechanistic target of rapamycin complex 1 (mTORC1) using rapamycin leads to partially inhibited mTORC1 activation, along with increased MPS, and muscle hypertrophy after HiMC. Therefore, we hypothesized that rapamycin-sensitive mTORC1 regulates myofibrillar protein translation, and the purpose of this study was to investigate this possibility. The right gastrocnemius muscle of male Sprague Dawley rats was contracted isometrically via percutaneous electrical stimulation, and the left gastrocnemius muscle served as control. Vehicle or rapamycin was intraperitoneally injected 1 h before HiMC. Gastrocnemius muscles were collected at 6 h after a bout of HiMC and 48 h after chronic muscle contractions for 4 wk (3 HiMC per week). Rapamycin completely inhibited HiMC-induced activation of 70 kDa ribosomal protein S6 kinase, which is a rapamycin-sensitive mTORC1 substrate. However, rapamycin completely inhibited HiMC-induced dissociation of eukaryotic translation initiation factor 4E (eIF4E):eukaryotic translation initiation factor 4E (eIF4E)-binding protein (4E-BP1) and the interaction of eIF4E:eIF4G, despite the HiMC-induced phosphorylation of 4E-BP1 (Thr37/46, Thr70, and Ser65) being unaffected by rapamycin. Importantly, HiMC-induced myofibrillar protein synthesis was not influenced by rapamycin. Changes in myosin and actin levels relative to muscle mass induced by chronic muscle contraction remained constant even under rapamycin administration. These results indicated that rapamycin-sensitive mTORC1 signaling is not fully responsible for contraction-induced increases in myofibrillar protein synthesis.NEW & NOTEWORTHY Muscle contraction activates mTOR signaling, resulting in increased protein synthesis and muscle hypertrophy. Rapamycin-sensitive mTORC1 is important for cap-dependent translation, but the effects of suppressing mTORC1 function using rapamycin on myofibrillar protein synthesis caused by contraction remains unclear. We observed that the eIF4F complex is a translation initiator induced by contraction dependently on rapamycin-sensitive mTORC1. Myofibrillar protein translation increased by muscle contraction was insensitive to rapamycin.

Linking molecular interactions to ecological impacts: how thiamethoxam in aquatic environments inhibits tadpole growth by disrupting bile acid homeostasis.