bims-moremu 2025-06-01 papers

bims-moremu

Biomed News

on Molecular regulators of muscle mass

Issue of 2025–06–01
thirty-two papers selected by
Anna Vainshtein, Craft Science Inc.

Dux Is Dispensable for Skeletal Muscle Regeneration: A Study Inspired by a "Red Flagged" Publication and Editorial Oversight.
Training-induced plasma miR-29a-3p is secreted by skeletal muscle and contributes to metabolic adaptations to resistance exercise in mice.
Molecular landscape of sex- and modality-specific exercise adaptation in human skeletal muscle through large-scale multi-omics integration.
Muscle-homing peptides modified biomimetic curcumin nanoparticles ameliorate skeletal muscle dysfunction in aging mice.
SESN2 mediates resistance training-induced improvements in exercise performance and energy metabolism in C57BL/6J mice.
Myotendinous junction: a microenvironment favorable for short-term adaptations to resistance training following gastrocnemius muscle atrophy.
The molecular transition that confers voltage dependence to muscle contraction.
Chronic and acute mediators of passive viscoelasticity in human skeletal muscle fibres.
Ephrin-A5 or EphA7 stimulation is anti-proliferative for human rhabdomyosarcoma in vitro.
SERCA activation prevents Ca2+ and ATP upregulation during three-day soleus muscle unloading in rats.
Misregulation of the Ubiquitin-Proteasome System and Autophagy in Muscular Dystrophies Associated with the Dystrophin-Glycoprotein Complex.
Targeting Muscle Regeneration with Small Extracellular Vesicles from Adipose Tissue-Derived Stem Cells-A Review.
Downhill running induced mitophagy in rat soleus muscle via the AMPK pathway.
Patient-Oriented In Vitro Studies in Duchenne Muscular Dystrophy: Validation of a 3D Skeletal Muscle Organoid Platform.
Antioxidant supplementation blunts the proteome response to 3 weeks of sprint interval training preferentially in human type 2 muscle fibres.
Targeting Myostatin as an Adjunct Treatment for the Preservation of Cardiometabolic and Skeletal Muscle Function in Type 1 Diabetes.
The effect of arsenic on mitochondrial fatty acid metabolism via inhibition of carnitine palmitoyltransferase 1B and choline kinase beta in C2C12 cells.
Exploration of Pathogenesis and Cutting-Edge Treatment Strategies of Sarcopenia: A Narrative Review.
Personalized molecular signatures of insulin resistance and type 2 diabetes.
The skeletal muscle response to high-intensity training assessed by single-nucleus RNA-sequencing is blunted in individuals with type 2 diabetes.
Protocol for in vivo lineage tracing of regeneration-associated macrophages from injured skeletal muscle of adult mice.
Skeletal muscle endothelial dysfunction through the activin A-PGC1α axis drives progression of cancer cachexia.
Dissection and Whole-Mount Immunofluorescent Staining of Mouse Hind Paw Muscles for Neuromuscular Junction Analysis.
Citrinin delays muscle aging and extends lifespan in C. elegans and prevents senescence in C2C12 through SKN-1/Nrf2 activation.
Cinnamic acid-GPR109A pathway improves skeletal muscle hypertrophy and metabolism.
Ngn2-Induced Differentiation of the NG108-15 Cell Line Enhances Motor Neuronal Differentiation and Neuromuscular Junction Formation.
Secreted EMC10 inhibits muscle GLUT4 activity and glucose uptake in mice.
Intermittent Supplementation With Fisetin Improves Physical Function and Decreases Cellular Senescence in Skeletal Muscle With Aging: A Comparison to Genetic Clearance of Senescent Cells and Synthetic Senolytic Approaches.
CD9, a novel potential biomarker of sarcopenia.
Editorial: Emerging trends in cardiac and skeletal muscle pharmacotherapy.
Potential effect of Irisin on sarcopenia: a systematic review.
Evaluation of aggrephagy markers in myofibrillar myopathies.

Cells. 2025 05 12. pii: 695. [Epub ahead of print]14(10):

Dux Is Dispensable for Skeletal Muscle Regeneration: A Study Inspired by a "Red Flagged" Publication and Editorial Oversight.

Kenric Chen, Erdong Wei, Ana Mitanoska, Micah D Gearhart, Michael Kyba, Darko Bosnakovski.

  Double homeobox (DUX) genes are key embryonic regulators that are silenced after the early cleavage stages of embryogenesis. Aberrant expression of DUX4 in skeletal muscle is linked to facioscapulohumeral muscular dystrophy (FSHD). A recent study reported that Dux, the murine ortholog of DUX4, contributes to the dystrophic phenotype in mdx mice, a Duchenne muscular dystrophy (DMD) model, and that its deletion enhances muscle regeneration by reducing oxidative stress. However, convincing evidence of Dux expression in either intact or injured muscle of wild-type (WT) and mdx mice remains lacking, raising questions about its role in muscle homeostasis. To investigate this, we assessed Dux expression in WT and mdx mice and used Dux knockout (DuxΔ/Δ) mice to evaluate its function during regeneration following cardiotoxin (CTX)-induced injury. Contrary to prior reports, Dux was not expressed in either WT or mdx mice. Moreover, Dux deletion did not enhance muscle regeneration or affect the expression of the oxidative stress regulator Nrf2 following CTX injury. Lastly, we confirmed that neither DUX4 nor its target genes were induced in muscle biopsies from DMD patients, excluding a role for DUX4 in DMD pathology. Collectively, our results demonstrate that Dux does not impact skeletal muscle regeneration or DUX4 contribution to the DMD dystrophic phenotype, directly challenging the conclusions of a previously published study. We comment on issues of editorial oversight that led to the publication of that study and highlight the deleterious impact of the growing wave of fraudulent publications.

Keywords:  DUX4; Duchenne muscular dystrophy (DMD); Dux; Facioscapulohumeral muscular dystrophy (FSHD); mdx; muscle regeneration

DOI:  https://doi.org/10.3390/cells14100695
Mol Metab. 2025 May 23. pii: S2212-8778(25)00080-8. [Epub ahead of print] 102173

Training-induced plasma miR-29a-3p is secreted by skeletal muscle and contributes to metabolic adaptations to resistance exercise in mice.

Paola Pinto-Hernandez, Manuel Fernandez-Sanjurjo, Daan Paget, Xurde M Caravia, David Roiz-Valle, Juan Castilla-Silgado, Sergio Diez-Robles, Almudena Coto-Vilcapoma, David Fernandez-Vivero, Pau Gama-Perez, Pablo M Garcia-Roves, Carlos Lopez-Otin, Juleen Zierath, Anna Krook, Benjamin Fernandez-Garcia, Cristina Tomas-Zapico, Eduardo Iglesias-Gutierrez.

  It remains unclear whether the adaptive response to different exercise models is mediated by extracellular vesicle (EV) microRNAs (miRNAs) released from skeletal muscle and their functional metabolic role. We sequenced miRNA-loaded plasma EVs obtained from mice after 4-weeks of endurance or resistance training. Resistance exercise increased the expression of a 11-miRNA profile grouped into two functional clusters. Using both genetically modified murine and cellular models, we have identified miR-29a-3p as a molecular mediator released in EVs in response to skeletal muscle contraction. Moreover, miR-29a-3p also seems to have a relevant role in the adaptation to resistance training by contributing to modulate the expression and secretion of other miRNAs and energy metabolism in muscle and liver. Taken together, our study suggests miR-29a-3p as a training-induced molecular mediator in the response and adaptation to resistance training, possibly due to its regulatory role in energy metabolism.

Keywords:  energy metabolism; exercise training; extracellular vesicles; miR-29 family; microRNAs

DOI:  https://doi.org/10.1016/j.molmet.2025.102173
Cell Rep. 2025 May 28. pii: S2211-1247(25)00521-2. [Epub ahead of print]44(6): 115750

Molecular landscape of sex- and modality-specific exercise adaptation in human skeletal muscle through large-scale multi-omics integration.

Macsue Jacques, Shanie Landen, Adam P Sharples, Andrew Garnham, Ralf Schittenhelm, Joel Steele, Aino Heikkinen, Elina Sillanpää, Miina Ollikainen, James Broatch, Navabeh Zarekookandeh, Ola Hanson, Ola Ekström, Olof Asplund, Séverine Lamon, Sarah E Alexander, Cassandra Smith, Carlie Bauer, Mary N Woessner, Itamar Levinger, Andrew E Teschendorff, Linn Gillberg, Ida Blom, Jørn Wulff Helge, Nicholas R Harvey, Larisa M Haupt, Lyn R Griffiths, Atul S Deshmukh, Kirsi H Pietiläinen, Päivi Piirilä, Robert A E Seaborne, Marie Klevjer, Anja Bye, Ulrik Wisløff, Bernadette Jones-Freeman, Nir Eynon.

  We investigated the molecular mechanisms of exercise adaptations in human muscle by integrating genome, methylome, transcriptome, and proteome data from over 1,000 participants (2,340 muscle samples). We identified distinctive signatures associated with maximal oxygen consumption (VO2max), and multi-omics integration uncovered five key genes as robust exercise markers across layers, with transcription factors functioning as activators, synergizing with DNA methylation to regulate gene expression. Minimal sex differences were observed, while modality-specific analysis highlighted distinct pathways for aerobic and resistance exercise, contrasting with muscle disuse patterns. Finally, we created a webtool, OMAx, featuring our individual omics and integration analysis. These findings provide a comprehensive multi-omics framework for understanding exercise-induced molecular adaptations, offering insights into muscle health, cardiorespiratory fitness, and their roles in aging and disease prevention.

Keywords:  CP: Metabolism; DNA methylation; Multi Omics; VO(2 max); epigenetics; exercise; gene expression; proteomic; skeletal muscle; transcriptomic

DOI:  https://doi.org/10.1016/j.celrep.2025.115750
Redox Biol. 2025 May 14. pii: S2213-2317(25)00192-2. [Epub ahead of print]84 103679

Muscle-homing peptides modified biomimetic curcumin nanoparticles ameliorate skeletal muscle dysfunction in aging mice.

Jianjie Xie, Zongyu Huang, Nana Gao, Huicong Feng, Biaobiao Wang, Shuang Gao, He Tian, Chao Wu, Chang Liu.

  With increasing age, skeletal muscle gradually loses mass and strength, and the risk of falls and fractures escalates among elderly individuals. Inflammation is closely related to age-related muscle atrophy and is the potential target for treating muscular atrophy. Here, biomimetic curcumin nanoparticles (M12MNCs) are prepared via encapsulating curcumin in the skeletal muscle cell membranes modified via muscle-homing peptides (M12) for the treatment of aging related skeletal muscle atrophy. The M12MNCs have good biocompatibility and can be enriched in aging skeletal muscle. After treatment with the M12MNCs, aging mice present enhanced motor ability and improved skeletal muscle metabolism. The results of in vivo and in vitro experiments confirm that M12MNCs reduce inflammation and decrease the expression of α-synuclein (α-syn). In addition, M12MNCs ameliorate skeletal muscle dysfunction in aging mice via regulating the SphK1/Spns2/S1PR2 axis. This study provides a therapeutic target of inflammatory and myogenic factors to improve the function of aging skeletal muscle, which provides valuable insights for the subsequent treatment of aging-related skeletal muscle function. These findings suggest that M12MNCs can improve age-related skeletal muscle dysfunction by modulating inflammation and cell proliferation, and can be used as a novel drug delivery system for clinical therapeutic regimens for muscle atrophy.

Keywords:  Aging; Curcumin; Inflammation; Muscle-homing peptide; Nanocrystal; Skeletal muscle

DOI:  https://doi.org/10.1016/j.redox.2025.103679
Exp Cell Res. 2025 May 25. pii: S0014-4827(25)00213-7. [Epub ahead of print]450(1): 114617

SESN2 mediates resistance training-induced improvements in exercise performance and energy metabolism in C57BL/6J mice.

Yating Huang, Shiqi Sun, Xuege Yang, Xiuru Li, Yanshuo Zhou, Sujuan Liu, Yanmei Niu, Li Fu.

  Long-term resistance training promotes skeletal muscle hypertrophy and boosts energy metabolism. The stress-inducible protein, SESN2 is a mediator of aerobic training benefits. However, whether SESN2 mediates resistance training to promote skeletal muscle hypertrophy and energy metabolism remains elusive. In this study, eight-week-old C57BL/6J male wild-type (WT) and SESN2-/- mice were subjected to resistance training intervention for 12 weeks. Our results revealed that SESN2 deficiency weakened the effects of resistance training on the increase of grip strength, maximum load capacity, time to exhaustion, and grid suspension time. SESN2 promoted skeletal muscle hypertrophy by inhibiting protein degradation in response to resistance training. Moreover, SESN2 ablation blocked the resistance training-induced improvements in oxygen consumption, carbon dioxide production and energy expenditure. Glycolysis and tricarboxylic acid cycle in skeletal muscle of SESN2-/- mice remain unchanged after resistance training. Furthermore, SESN2 deletion did not alter the expression of key metabolic enzymes in glycolysis and tricarboxylic acid cycle in both atrophied skeletal muscle and resistance exercise preconditioned muscle. These results imply that the SESN2 is a crucial regulator in facilitating the beneficial effects of resistance training on exercise performance, skeletal muscle mass and energy metabolism. This study contributes to the understanding of the mechanisms by which resistance training promotes skeletal muscle energy metabolism.

Keywords:  Energy metabolism; Muscle mass; Resistance training; SESN2

DOI:  https://doi.org/10.1016/j.yexcr.2025.114617
Front Physiol. 2025 ;16 1493820

Myotendinous junction: a microenvironment favorable for short-term adaptations to resistance training following gastrocnemius muscle atrophy.

Lara Caetano Rocha-Braga, Jurandyr Pimentel Neto, Isabella Gomes, Adriano Polican Ciena.

  The myotendinous junction (MTJ) is an interface region between the skeletal muscle fibers and the tendon, specialized in force transmission, and has a wide capacity to adapt to different stimuli. Disuse muscle atrophy is a deleterious effect of joint immobilization, which is used as a conservative treatment for bone, muscle, and joint injuries and promotes a significant functional decline. Physical exercise is an effective therapeutic modality in combating muscle atrophy, especially resistance training that promotes hypertrophic responses. We aimed to investigate the plasticity of the MTJ in rats subjected to joint immobilization, followed by resistance training in a short period (7 and 14 days). Forty-eight male Wistar rats (90 days old) were used and divided into groups (n = 8): Control (C), Immobilized (I), Trained (T), and Immobilized Trained (IT). The MTJ samples of gastrocnemius muscle were collected and processed for morphoquantitative analyses using transmission electron microscopy (MTJ and sarcomeres morphometry) and immunofluorescence techniques for collagen XXII, satellite cells and telocytes. We observed that the I group exhibited a reduction in muscle mass, which was associated with a decrease in the length of sarcoplasmic invaginations and evaginations, as well as reductions in belly and proximal sarcomere length. Conversely, the IT groups demonstrated a progressive increase in muscle mass, with significant improvements from 7 days (p < 0.01) to 14 days (p < 0.0001). The most pronounced adaptations in sarcoplasmic projections were observed in the IT14 group, which exhibited: a significant increase in the length of sarcoplasmic invaginations (p < 0.05); a marked increase in sarcoplasmic evaginations (p < 0.001); a substantial enlargement of the belly sarcomere (p < 0.0001) and proximal sarcomere (p < 0.0001); and a notable expansion of the collagen XXII perimeter (p < 0.001). We concluded that the joint immobilization resulted in muscle atrophy due to disuse, which led to a decrease in sarcoplasmic projections in the MTJ, a reduction in the perimeter of collagen XXII, and, consequently, fragility of the region. Short-term training demonstrated positive effects on functional improvement, partial recovery of muscle mass, and induction of hypertrophic responses, indicating positive repercussions for the structural recovery of the myotendinous region.

Keywords:  collagen XXII; joint immobilization; satellite cell; skeletal muscle atrophy; telocyte

DOI:  https://doi.org/10.3389/fphys.2025.1493820
Nat Commun. 2025 May 24. 16(1): 4847

The molecular transition that confers voltage dependence to muscle contraction.

Marina Angelini, Nicoletta Savalli, Federica Steccanella, Savana Maxfield, Serena Pozzi, Marino DiFranco, Stephen C Cannon, Antonios Pantazis, Riccardo Olcese.

What is the molecular origin of voltage dependence in skeletal muscle excitation-contraction? Cholinergic transmission to the muscle fiber triggers action potentials, which are sensed by voltage-gated L-type calcium channels (CaV1.1). In turn, the conformational changes in CaV1.1 propagate to and activate intracellular ryanodine receptors (RyR1), causing Ca2+ release and contraction. The CaV1.1 channel has four voltage-sensing domains (VSD-I to -IV) with diverse voltage-sensing properties, so the identity of VSD(s) responsible for conferring voltage dependence to RyR1 opening, is unknown. Using voltage-clamp fluorometry, we show that only VSD-III possesses kinetic, voltage-dependent and pharmacological properties consistent with skeletal-muscle excitability and Ca2+ release. We propose that the earliest voltage-dependent event in the excitation-contraction process is the structural rearrangement of VSD-III that propagates to RyR1 to initiate Ca2+ release and contraction.

DOI: https://doi.org/10.1038/s41467-025-59649-7
Exp Physiol. 2025 May 26.

Chronic and acute mediators of passive viscoelasticity in human skeletal muscle fibres.

Grace E Privett, Austin W Ricci, Karen Wiedenfeld Needham, Damien M Callahan.

  The cellular viscoelastic modulus in skeletal muscle tissue responds dynamically to chronic stressors, such as age and exercise. Passive tissue mechanics can also be sensitive to acute stimuli, such as mechanical loading and/or activation-induced muscle fatigue. These insights are largely derived from preclinical studies of age and acute muscle activation. Therefore, we sought to understand the relative responsiveness of muscle cellular passive mechanics to chronic (resistance training) and acute (exercise-induced muscle fatigue) stressors in healthy young males and females categorized as 'resistance trained' or 'untrained'. We measured passive mechanics to test the hypothesis that Young's modulus and stress would be greater in fibres from trained versus untrained participants and that both would be reduced following fatigue. We also assessed the translation of these findings to composite tissue in a subset of volunteers where muscle tissue bundles, containing both fibres and extracellular matrix, were analysed in addition to single fibres. We found that resistance-trained individuals demonstrated enhanced passive elastic and viscous modulus compared with non-trained individuals. We also report reductions in passive mechanical measures following fatiguing exercise. Surprisingly, both chronic and acute effectors of passive mechanics were observed in muscle fibres only from males, whereas females showed a more variable response across conditions. Last, we provide preliminary evidence supporting the translation of per-individual cellular differences to the tissue level. Together, these data suggest that males respond more dynamically to acute and chronic stressors of muscle tissue mechanics, potentially linking cellular response and sex-dependent differences in functional outcomes across the lifespan.

Keywords:  cellular stiffness; fatigue; passive mechanics; skeletal muscle; stress decay; titin; training; viscoelasticity

DOI:  https://doi.org/10.1113/EP092361
Skelet Muscle. 2025 May 27. 15(1): 14

Ephrin-A5 or EphA7 stimulation is anti-proliferative for human rhabdomyosarcoma in vitro.

Alessandra Cecchini, Lorenzo Ceccon, Steven Calandro, Anna Chen, Jenna K Schwesig, Ddw Cornelison.

Rhabdomyosarcoma (RMS) is a tumor which resembles skeletal muscle. Current treatments are limited to surgery and non-targeted chemotherapy, highlighting the need for alternative therapies. Differentiation therapy uses molecules that act to shift the tumor cells' phenotype from proliferating to differentiated, which in the case of skeletal muscle includes exit from the cell cycle and potentially fusion into myofibers. We previously identified EphA7 expressed on terminally differentiated myocytes as a potent driver of skeletal muscle differentiation: stimulation of ephrin-A5-expressing myoblasts with EphA7 causes them to undergo rapid, collective differentiation. We therefore tested EphA7 as a candidate molecule for differentiation therapy on human RMS (hRMS) cell lines. Surprisingly, EphA7 had a lesser effect than ephrin-A5, a difference explained by the divergent suite of Ephs and ephrins expressed by hRMS. We show that in hRMS ephrin-A5 binds and signals to EphA8 and EphA7 binds and signals to ephrin-A2, and that Fc chimeras of both molecules are potent inhibitors of hRMS proliferation. These results identify key differences between hRMS and normal muscle cells and support further research into Eph: ephrin signaling as potential differentiation therapies.

DOI: https://doi.org/10.1186/s13395-025-00384-4
Am J Physiol Regul Integr Comp Physiol. 2025 May 28.

SERCA activation prevents Ca2+ and ATP upregulation during three-day soleus muscle unloading in rats.

Ksenia Askhatovna Zaripova, Svetlana P Belova, Kristina A Sharlo, Darya A Sidorenko, Tatiana Y Kostrominova, Boris S Shenkman, Tatiana L Nemirovskaya.

  Background. The imbalance in the ratio of protein synthesis versus protein degradation results in skeletal muscle atrophy following unloading. The onset of these processes is regulated by the sarcoplasmic concentrations of ATP and calcium (Ca2+). We tested the hypothesis that unloading-induced inactivation of SERCA results in raised Ca2+ concentrations, triggering catabolic processes. CDN1163, an activator of SERCA, was used to test this hypothesis. Methods. Three groups of male rats were used: control rats with intraperitoneal injection of placebo (C), 3 days of unloading with placebo injection (3HS), and 3 days of unloading injected with CDN1163 (3HSC). Results. Treatment with CDN1163 during three days of soleus muscle unloading prevented the upregulation of Ca2+ and ATP, and the slow-to-fast shift in muscle fiber composition. This treatment blocked the decrease in the phosphorylation of the anabolic markers (GSK3b, eEF2, and S6(Ser240/244/ Ser235/236)), and therefore it is likely that it improved the efficiency of translation in the unloaded muscle, but it did not affect mTORC1-dependent signaling. Treatment with CDN1163 also modulated the regulation of the Ca2+-dependent signaling in muscle during unloading via SERCA1 and CSQ2, and changes in the CaMKII phosphorylation and the content of IP3R. In addition, CDN1163 prevented the upregulation of the mRNA expression of MuRF1 (but not MAFbx) and attenuated the increase of Cbl-b and ubiquitin mRNA expression during unloading. Conclusions. Activation of SERCA with CDN1163 prevents the upregulation of Ca2+ and ATP, as well as calcium-dependent and ubiquitin-proteasome pathways markers, and improves protein translation efficiency in three-day unloaded soleus muscle.

Keywords:  AMPK; ATP; CaMKII; MuRF1; atrophy; unloading

DOI:  https://doi.org/10.1152/ajpregu.00177.2024
Cells. 2025 05 15. pii: 721. [Epub ahead of print]14(10):

Misregulation of the Ubiquitin-Proteasome System and Autophagy in Muscular Dystrophies Associated with the Dystrophin-Glycoprotein Complex.

Manuela Bozzi, Francesca Sciandra, Maria Giulia Bigotti, Andrea Brancaccio.

  The stability of the sarcolemma is severely impaired in a series of genetic neuromuscular diseases defined as muscular dystrophies. These are characterized by the centralization of skeletal muscle syncytial nuclei, the replacement of muscle fibers with fibrotic tissue, the release of inflammatory cytokines, and the disruption of muscle protein homeostasis, ultimately leading to necrosis and loss of muscle functionality. A specific subgroup of muscular dystrophies is associated with genetic defects in components of the dystrophin-glycoprotein complex (DGC), which plays a crucial role in linking the cytosol to the skeletal muscle basement membrane. In these cases, dystrophin-associated proteins fail to correctly localize to the sarcolemma, resulting in dystrophy characterized by an uncontrolled increase in protein degradation, which can ultimately lead to cell death. In this review, we explore the role of intracellular degradative pathways-primarily the ubiquitin-proteasome and autophagy-lysosome systems-in the progression of DGC-linked muscular dystrophies. The DGC acts as a hub for numerous signaling pathways that regulate various cellular functions, including protein homeostasis. We examine whether the loss of structural stability within the DGC affects key signaling pathways that modulate protein recycling, with a particular emphasis on autophagy.

Keywords:  autophagy; dystroglycan; dystroglycanopathies; dystrophin; proteasome degradation

DOI:  https://doi.org/10.3390/cells14100721
Cells. 2025 05 09. pii: 683. [Epub ahead of print]14(10):

Targeting Muscle Regeneration with Small Extracellular Vesicles from Adipose Tissue-Derived Stem Cells-A Review.

Lucas Fornari Laurindo, Enzo Pereira de Lima, Adriano Cressoni Araújo, Victória Dogani Rodrigues, Jefferson Aparecido Dias, Marcos Barbosa Tavares Filho, Debora Aparecida Pires de Campos Zuccari, Lívia Fornari Laurindo, Maria Angélica Miglino, Eduardo Federighi Baisi Chagas, Claudemir Gregório Mendes, Rosa Direito, Vítor Engrácia Valenti, Sandra Maria Barbalho.

  Extracellular vesicles (EVs) are membrane-bound structures released by cells carrying diverse biomolecules involved in intercellular communication. Small EVs are abundant in body fluids, playing a key role in cell signaling. Their natural occurrence and therapeutic potential, especially in the context of muscular disorders, make them a significant area of research. Sarcopenia, characterized by progressive muscle fiber loss, represents a pathological state in which EVs could offer therapeutic benefits, reducing morbidity and mortality. Recent studies have proposed an interplay between adipose tissue (AT) and skeletal muscle regarding sarcopenia pathology. AT dysregulation, as seen in obesity, contributes to skeletal muscle loss in a multifactorial way. While AT-derived stem cell (ATDSC) small EVs have been implicated in musculoskeletal homeostasis, their precise action in muscle regeneration remains incompletely understood. In this context, ATDSC-derived small EVs can stimulate skeletal muscle regeneration through improved proliferation and migration of muscle cells, enhancement of muscular perfusion, improvement of tendon and nerve regeneration, stimulation of angiogenesis, and promotion of myogenic differentiation. However, they can also increase skeletal muscle loss. Notably, this is the first comprehensive review to systematically examine the role of ATDSC-derived small EVs in sarcopenia.

Keywords:  adipose tissue-derived stem cells; aging-related muscle loss; muscle regeneration; sarcopenia; skeletal muscles; small extracellular vesicles

DOI:  https://doi.org/10.3390/cells14100683
J Physiol Biochem. 2025 May 24.

Downhill running induced mitophagy in rat soleus muscle via the AMPK pathway.

Huayu Shang, Ranggui Ma, Shengju Chen, Hao Deng, Mengyu Li, Shiqiao Zheng, He Zhang, Duo Zhang, Tianai Yang, Ying Yang, Zhi Xia.

  Eccentric exercise is known to induce more pronounced muscle damage associated with delayed-onset muscle soreness than concentric exercise. This study aimed to investigate whether AMP-activated protein kinase (AMPK) pathway participates in control of mitophagy in rat skeletal muscle in response to downhill running. Eighty-eight male Sprague-Dawley rats were exercised on a treadmill tilted at 16° decline at 16 m·min- 1 for 90 min, with the soleus muscle sampled at 0 h, 12 h, 24 h, 48 h and 72 h after exercise. The AMPK inhibitor compound C or AMPK activator AICAR or saline was injected intraperitoneally 20 min before exercise. After downhill treadmill running, the skeletal muscle mitochondrial structure appeared to be abnormal and contained mitophagosomes; the expression levels of AMPK phosphorylation, cyclophilin D (CypD), cytochrome C (CytC), mitochondrial FK506-binding protein 8 (FKBP8), microtubule-associated protein 1 light chain 3 (LC3), and the co-localization of FKBP8 with LC3 and mitochondria with dynamin-related protein 1 (Drp1), lysosomal-associated membrane protein 2 (LAMP2) were significantly higher; the expression levels of mechanistic target of rapamycin (mTOR Ser2448) phosphorylation and heat shock protein 60 (HSP60), mitochondrial respiratory complex I (NDUFB8) and complex III (UQCRC2), and adenosine triphosphate (ATP) content were significantly lower than those in the C group. Further study showed that the effect of downhill treadmill running was partly blocked by compound C and strengthened by AICAR. A session of downhill treadmill running activated the AMPK pathway and promoted LC3 co-localizations with mitochondria and FKBP8, and induced mitophagy and mitochondrial damage within rat skeletal muscle.

Keywords:  AMP-activated protein kinase; Downhill treadmill running; FK506-binding protein 8; Mitophagy; Skeletal muscle

DOI:  https://doi.org/10.1007/s13105-025-01093-8
Biomedicines. 2025 May 03. pii: 1109. [Epub ahead of print]13(5):

Patient-Oriented In Vitro Studies in Duchenne Muscular Dystrophy: Validation of a 3D Skeletal Muscle Organoid Platform.

Raffaella Quarta, Enrica Cristiano, Mitchell K L Han, Brigida Boccanegra, Manuel Marinelli, Nikolas Gaio, Jessica Ohana, Vincent Mouly, Ornella Cappellari, Annamaria De Luca.

  Background: Three-dimensional skeletal muscle organoids (3D SkMO) are becoming of increasing interest for preclinical studies in Duchenne muscular dystrophy (DMD), provided that the used platform demonstrates the possibility to form functional and reproducible 3D SkMOs, to investigate on potential patient-related phenotypic differences. Methods: In this study, we employed fibrin-based 3D skeletal muscle organoids derived from immortalized myogenic precursors of DMD patients carrying either a stop codon mutation in exon 59 or a 48-50 deletion. We compared dystrophic lines with a healthy wild-type control (HWT) by assessing microtissue formation ability, contractile function at multiple timepoints along with intracellular calcium dynamics via calcium imaging, as well as expression of myogenic markers. Results: We found patient-specific structural and functional differences in the early stages of 3D SkMO development. Contractile force, measured as both single twitch and tetanic responses, was significantly lower in dystrophic 3D SkMOs compared to HWT, with the most pronounced differences observed at day 7 of differentiation. However, these disparities diminished over time under similar culturing conditions and in the absence of continuous nerve-like stimulation, suggesting that the primary deficit lies in delayed myogenic maturation, as also supported by gene expression analysis. Conclusions: Our results underline that, despite the initial maturation delay, DMD muscle precursors retain the capacity to form functional 3D SkMOs once this intrinsic lag is overcome. This suggests a critical role of dystrophin in early myogenic development, while contraction-induced stress and/or an inflammatory microenvironment are essential to fully recapitulate dystrophic phenotypes in 3D SkMOs.

Keywords:  3D skeletal muscle organoid; Duchenne muscular dystrophy; disease modeling; immortalized human myoblast; tissue engineering

DOI:  https://doi.org/10.3390/biomedicines13051109
J Physiol. 2025 May 28.

Antioxidant supplementation blunts the proteome response to 3 weeks of sprint interval training preferentially in human type 2 muscle fibres.

Victoria L Wyckelsma, Marta Murgia, Sigitas Kamandulis, Stefano Gastaldello, Marius Brazaitis, Audrius Snieckus, Nerijus Eimantas, Mati Pääsuke, Sebastian Edman, William Apro, Daniel C Andersson, Håkan Westerblad, Tomas Venckunas.

  Sprint interval training (SIT) is a time-efficient type of endurance training that involves large type 2 muscle fibre recruitment. Effective antioxidant supplementation may mitigate positive training adaptations by limiting the oxidant challenge. Our aim was to test whether SIT affects type 2 more than type 1 muscle fibres, and whether the muscular training response is mitigated by antioxidant treatment. Young men performed three weekly SIT sessions (4-6 × 30 s all-out cycling) for 3 weeks while treated with antioxidants (vitamin C, 1 g day-1; vitamin E, 235 mg day-1) or placebo. Vastus lateralis biopsies were taken to measure (i) activation of genes for reactive oxygen/nitrogen species (ROS) sensors and inflammatory mediators with quantitative RT-PCR and (ii) fibre type-specific proteome adaptations using MS-based proteomics. Vitamin treatment decreased the upregulation of genes for ROS sensors and inflammatory regulators during the first SIT session. The 3 weeks of SIT caused generally larger proteome adaptations in type 2 than in type 1 fibres, and this included larger increases in abundance of proteins involved in mitochondrial energy production. Vitamin treatment blunted the SIT-induced proteome adaptations, whereas it did not affect the training-induced improvement in maximal cycling performance. In conclusion, (i) the large type 2 fibre recruitment and resulting proteome adaptations are instrumental to the effectiveness of SIT and (ii) antioxidant supplementation counteracts positive muscular adaptations to SIT, which would blunt any improvement in submaximal endurance performance, whereas it does not affect the improvement in maximal cycling performance, where O2 delivery to muscle would be limiting. KEY POINTS: Sprint interval training (SIT) is a time-efficient type of endurance training that involves large recruitment of fast-twitch muscle fibres. Treatment with antioxidants may mitigate the positive effects of endurance training. Fibre type-specific proteomics performed on muscle biopsies obtained from young men before and after 3 weeks of SIT showed larger training effects in fast- than in slow-twitch fibres. Antioxidant treatment in the form of vitamin C and E pills counteracted the positive muscular adaptations to the 3 weeks of SIT. These results increase our understanding of why SIT is an effective endurance training regime and provide further evidence against the common belief that antioxidant supplements are beneficial in a physical exercise context.

Keywords:  antioxidants; muscle fibre types; proteomics; reactive oxygen/nitrogen species; skeletal muscle; sprint interval training

DOI:  https://doi.org/10.1113/JP288638
Int J Mol Sci. 2025 May 18. pii: 4830. [Epub ahead of print]26(10):

Targeting Myostatin as an Adjunct Treatment for the Preservation of Cardiometabolic and Skeletal Muscle Function in Type 1 Diabetes.

Emily Nunan, Denton R Huff, Jillian L Gore, Carson L Wright, Tag Harris, Landon Butler, Caleb A Padgett, Matthew T Rochowski, Pamela C Lovern, Ali Boolani, Cammi Valdez, Joshua T Butcher.

  Type 1 Diabetes Mellitus (T1D) is a disease characterized by the destruction of pancreatic beta cells. The subsequent loss of insulin production results in hyperglycemia, muscle wasting, and vascular dysfunction. Due to an inability to appropriately maintain glucose homeostasis, patients afflicted with T1D suffer from increased morbidity and early mortality. Skeletal muscle is the body's largest metabolic reservoir, absorbing significant amounts of glucose from the bloodstream and physical exercise is known to improve and prevent the progression of pathological outcomes, but many T1D patients are unable to exercise at a level that conveys benefit. Thus, directly targeting muscle mass and function may prove beneficial for improving T1D patient outcomes, independent of exercise. A potent negative regulator of skeletal muscle has been identified as being upregulated in T1D patients, namely the myokine myostatin. Our hypothesis is that targeting myostatin (via genetic deletion) will prevent glucose dysfunction in a T1D model, preserve skeletal muscle function, and protect against vascular and renal dysfunction. Our methods utilized adult male mice with (WT) and without myostatin (Myo KO), in combination with the chemical induction of T1D (streptozotocin). Experimental outcomes included the assessment of glucose homeostasis (plasma glucose, HbA1c, IGTT), metabolism, muscle function (in vivo plantarflexion), and skeletal muscle vascular function (ex vivo pressure myography). Our results described systemic benefits from myostatin deletion in the T1D model, independent of insulin, including the following: inhibition of T1D-induced increases in plasma glucose, prevention of functional deficits in muscle performance, and preservation of fluid dynamics. Further, endothelial function was preserved with myostatin deletion. Taken together, these data inform upon the use of myostatin inhibition as a therapeutic target for effective treatment and management of the cardiometabolic and skeletal muscle dysfunction that occurs with T1D.

Keywords:  endothelium; glucose homeostasis; metabolism; muscle performance; myostatin; skeletal muscle; type 1 diabetes

DOI:  https://doi.org/10.3390/ijms26104830
PLoS One. 2025 ;20(5): e0320557

The effect of arsenic on mitochondrial fatty acid metabolism via inhibition of carnitine palmitoyltransferase 1B and choline kinase beta in C2C12 cells.

Fu-Lin Yu, Ming-Yan Zhang, Gang-Wei Song, Yang-Shan Ning, Xian Wu, Yan Gao.

Arsenic can enter the human body through environmental exposure via food, drinking water, and chemotherapy for cancer. Prolonged and excessive exposure to arsenic causes various toxic reactions, leading to diseases that significantly impact health and lifespan. Increasing evidence suggests that arsenic damages skeletal muscle tissue by reducing muscle mass and causing atrophy, thereby contributing to conditions such as respiratory and cardiovascular diseases, as well as diabetes. Fatty acid β-oxidation is the most efficient mechanism for ATP production and serves as a primary energy source for tissues, including the heart and skeletal muscles. However, the metabolic mechanisms underlying arsenic's effects on muscle function and pathogenesis remain incompletely understood. In this study, we investigated the role of mitochondrial fatty acid oxidation in arsenic-induced muscular damage using mouse skeletal muscle C2C12 cells. Our results demonstrated a dose-dependent inhibitory effect of sodium arsenite (0-2 µM, 72 hours) on C2C12 cells proliferation, viability, and differentiation (indicated by reduction of myogenic differentiation 1 mRNA expression). Arsenic exposure disrupted mitochondria through increasing reactive oxygen species production, reducing mitochondrial membrane potential to 16.45%, downregulating mitochondrial fatty acid metabolism-related enzymes (carnitine palmitoyltransferase 1B to 15.05% and choline kinase beta mRNA to 49.94%), and decreasing mitochondrial DNA copy number to 42.08%. These findings suggest that arsenic-induced pathological changes in skeletal muscle are associated with impaired mitochondrial membrane function, disrupted fatty acid metabolism, and reduced mitochondrial DNA content in muscle cells.

DOI: https://doi.org/10.1371/journal.pone.0320557
Clin Interv Aging. 2025 ;20 659-684

Exploration of Pathogenesis and Cutting-Edge Treatment Strategies of Sarcopenia: A Narrative Review.

Yin Gao, Di Liu, Qixian Xiao, Shan Huang, Li Li, Baocheng Xie, Limin Zhou, Yi Qi, Yanzhi Liu.

  Sarcopenia a progressive and multifactorial musculoskeletal syndrome characterized by loss of muscle mass and function, poses a significant global health challenge, particularly in aging populations. Epidemiological studies reveal that sarcopenia affects approximately 5-10% of the general population, with prevalence rates escalating dramatically after age 60 to reach 10-27% in older adults. This age-associated increase contributes significantly to healthcare burdens by elevating risks of disability, frailty, and mortality. Despite its profound impact, current clinical approaches to sarcopenia remain limited. While resistance exercise and protein supplementation form the cornerstone of management, their efficacy is often constrained by poor long-term adherence and variable individual responses, highlighting the urgent need for more comprehensive and personalized treatment strategies. The pathogenesis of sarcopenia is complex and influenced by various factors, including aging, inflammation, nutritional deficits, physical inactivity, and mitochondrial dysfunction. However, the precise molecular mechanisms underlying this condition are still not fully understood. Recent research has made significant strides in elucidating the intricate mechanisms contributing to sarcopenia, revealing novel insights into its molecular and cellular underpinnings. Notably, emerging evidence points to the pivotal role of mitochondrial dysfunction, altered myokine profiles, and neuromuscular junction degeneration in sarcopenia progression. Additionally, breakthroughs in stem cell therapy, exosome-based treatments, and precision nutrition offer promising avenues for clinical intervention. This review aims to synthesize the latest advancements in sarcopenia research, focusing on the novel contributions to its pathogenesis and treatment strategies. We explore emerging trends such as the role of cellular senescence, epigenetic regulation, and targeted therapeutic interventions that could reshape future approaches to managing sarcopenia. By highlighting recent breakthroughs and cutting-edge research, we hope to advance the understanding of sarcopenia and foster the translation of these findings into effective clinical therapies.

Keywords:  aging; muscle; sarcopenia; skeleton

DOI:  https://doi.org/10.2147/CIA.S517833
Cell. 2025 May 21. pii: S0092-8674(25)00515-X. [Epub ahead of print]

Personalized molecular signatures of insulin resistance and type 2 diabetes.

Jeppe Kjærgaard, Ben Stocks, John Henderson, Jordana B Freemantle, David Rizo-Roca, Michele Puglia, Maria Madrazo Montoya, Daniel Andersson, Jesper Bäckdahl, Daniel Eriksson-Hogling, Jacob V Stidsen, Michael Wierer, Simon Rasmussen, Kei Sakamoto, Kurt Højlund, Mikael Rydén, Juleen R Zierath, Anna Krook, Atul S Deshmukh.

  Insulin resistance is a hallmark of type 2 diabetes, which is a highly heterogeneous disease with diverse pathology. Understanding the molecular signatures of insulin resistance and its association with individual phenotypic traits is crucial for advancing precision medicine in type 2 diabetes. Utilizing cutting-edge proteomics technology, we mapped the proteome and phosphoproteome of skeletal muscle from >120 men and women with normal glucose tolerance or type 2 diabetes, with varying degrees of insulin sensitivity. Leveraging deep in vivo phenotyping, we reveal that fasting proteome and phosphoproteome signatures strongly predict insulin sensitivity. Furthermore, the insulin-stimulated phosphoproteome revealed both dysregulated and preserved signaling nodes-even in individuals with severe insulin resistance. While substantial sex-specific differences in the proteome and phosphoproteome were identified, molecular signatures of insulin resistance remained largely similar between men and women. These findings emphasize the necessity of incorporating disease heterogeneity into type 2 diabetes care strategies.

Keywords:  disease heterogeneity; glucose metabolism; phosphoproteomics; sex differences; signaling; skeletal muscle

DOI:  https://doi.org/10.1016/j.cell.2025.05.005
J Physiol. 2025 May 25.

The skeletal muscle response to high-intensity training assessed by single-nucleus RNA-sequencing is blunted in individuals with type 2 diabetes.

Maria Hansen, Julius E R Grothen, Anders Karlsen, Jaime M Martinez, Nikos Sidiropoulos, Jørn W Helge, Thomas Å Pedersen, Flemming Dela.

  Training can improve insulin sensitivity in individuals with type 2 diabetes, but a clear understanding of the mechanisms remains elusive. To further our knowledge in this area, we aimed to examine the effect of type 2 diabetes and of high-intensity interval training (HIIT) on the nuclear transcriptional response in skeletal muscle. We performed single-nucleus RNA-sequencing (snRNA-seq) and immunofluorescence analysis on muscle biopsies from the trained and the untrained legs of participants with and without type 2 diabetes, after 2 weeks of one-legged HIIT on a cycle ergometer. Surprisingly, the type 2 diabetes condition only seemed to have a minor effect on transcriptional activity in myonuclei related to major metabolic pathways when comparing the untrained legs. However, while in particular the type IIA myonuclei in the control group displayed a considerable metabolic response to HIIT, with increases in genes related to glycogen breakdown and glycolysis primarily in the type IIA myonuclei of the trained leg, this response was blunted in the diabetes group, despite a marked increase in glucose clearance in both groups. Additionally, we observed that fibre type distribution assessed by immunofluorescence significantly correlated with the proportion of myonuclei in the snRNA-seq analysis. In conclusion, the type 2 diabetes condition blunts the metabolic transcriptional response to HIIT in the type IIA myonuclei without affecting the improvement in insulin sensitivity. Additionally, our results indicate that snRNA-seq can be used as a surrogate marker for fibre type distribution in sedentary middle-aged adults. KEY POINTS: The study utilized single-nucleus RNA sequencing (snRNA-seq) to analyse 38 skeletal muscle biopsies, revealing distinct transcriptional profiles in myonuclei from individuals with and without type 2 diabetes (T2D) after 2 weeks of HIIT. snRNA-seq identified significant differences in gene expression, with 14 differentially expressed genes (DEGs) in type IIA myonuclei of the control group, specifically related to glycogen breakdown and glycolysis, which were blunted in the T2D group. In the control group, HIIT induced a substantial transcriptional response in type IIA myonuclei, enhancing metabolic pathways associated with insulin sensitivity, while the T2D group showed minimal transcriptional changes despite improved insulin sensitivity. The T2D group exhibited a blunted response in metabolic gene expression, indicating that the training effect on muscle adaptation was significantly impaired compared to healthy controls. Overall, the findings highlight the differential impact of HIIT on muscle metabolism, emphasizing the need for tailored exercise interventions for individuals with T2D.

Keywords:  HIIT; glucose metabolism; snRNA‐seq; training; type 2 diabetes

DOI:  https://doi.org/10.1113/JP288368
STAR Protoc. 2025 May 24. pii: S2666-1667(25)00250-3. [Epub ahead of print]6(2): 103844

Protocol for in vivo lineage tracing of regeneration-associated macrophages from injured skeletal muscle of adult mice.

Neuza S Sousa, Pedro Sousa-Victor, Joana Neves.

  Macrophages undergo phenotypic transitions that are essential for successful skeletal muscle (SkM) regeneration. Here, we present a protocol for in vivo lineage tracing of regeneration-associated macrophages, combining genetic labeling with transplantation of fluorescence-activated cell sorting (FACS)-isolated cells. Macrophages isolated from congenic CD45.1+ donor mice are transplanted into pre-injured SkMs of CD45.2+ mice and phenotyped by flow cytometry at designated time points of the regenerative process. We describe steps for muscle injury, SkM tissue processing, macrophage isolation, transplantation, and flow cytometry phenotyping. For complete details on the use and execution of this protocol, please refer to Sousa et al.1.

Keywords:  Cell Biology; Cell isolation; Flow Cytometry; Immunology; Model Organisms

DOI:  https://doi.org/10.1016/j.xpro.2025.103844
Nat Cancer. 2025 May 26.

Skeletal muscle endothelial dysfunction through the activin A-PGC1α axis drives progression of cancer cachexia.

Young-Mee Kim, Mark A Sanborn, Shaluah Vijeth, Priyanka Gajwani, Xinge Wang, Dahee Jung, Tibor Valyi-Nagy, Sreeparna Chakraborty, Georgina Mancinelli, Peter T Toth, Evan H Phillips, Paul Grippo, Ameen A Salahudeen, Jooman Park, Su Yeon Yeon, Vijayalakshmi Ananthanarayanan, Yuwei Jiang, Steve Seung-Young Lee, Klara Valyi-Nagy, Jalees Rehman.

Cachexia is the wasting of skeletal muscle in cancer and is a major complication that impacts a person's quality of life. We hypothesized that cachexia is mediated by dysfunction of the vascular system, which is essential for maintaining perfusion and tempering inappropriate immune responses. Using transparent tissue topography, we discovered that loss of muscle vascular density precedes muscle wasting in multiple complementary tumor models, including pancreatic adenocarcinoma, colon carcinoma, lung adenocarcinoma and melanoma models. We also observed that persons suffering from cancer cachexia exhibit substantial loss of muscle vascular density. As tumors progress, increased circulating activin A remotely suppresses the expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α) in the muscle endothelium, thus inducing vascular leakage. Restoring endothelial PGC1α activity preserved vascular density and muscle mass in tumor-bearing mice. Our study suggests that restoring muscle endothelial function could be a valuable therapeutic approach for cancer cachexia.

DOI: https://doi.org/10.1038/s43018-025-00975-6
Bio Protoc. 2025 May 20. 15(10): e5315

Dissection and Whole-Mount Immunofluorescent Staining of Mouse Hind Paw Muscles for Neuromuscular Junction Analysis.

Rebecca L Simkin, Elena R Rhymes, Qiuhan Lang, Nicol Birsa, James N Sleigh.

  The neuromuscular junction (NMJ) is a peripheral synaptic connection between a lower motor neuron and skeletal muscle fibre that enables muscle contraction in response to neuronal stimulation. NMJ dysfunction and morphological abnormalities are commonly observed in neurological conditions, including amyotrophic lateral sclerosis, Charcot-Marie-Tooth disease, and spinal muscular atrophy. Employing precise and reproducible techniques to visualise NMJs in mouse models of neuromuscular disorders is crucial for uncovering aspects of neuropathology, revealing disease mechanisms, and evaluating therapeutic approaches. Here, we present a method for dissecting the deep lumbrical and flexor digitorum brevis (FDB) muscles of the mouse hind paw and describe the process of whole-mount immunofluorescent staining for morphological analysis of NMJs. Similar whole-mount techniques have been applied to other muscles, such as the diaphragm; however, dense connective tissue in adult samples often impedes antibody penetration. Moreover, large hind limb muscles, including the gastrocnemius and tibialis anterior, are commonly used to examine NMJs but require embedding and cryosectioning. These additional steps increase the complexity and duration of the protocol and can introduce sectioning artefacts, including transection of NMJs and disruption of morphology. Using small hind paw muscles enables whole-mounting, which completely eliminates the requirement for embedding and cryosectioning. As a result, the entire neuromuscular innervation pattern can be visualised, allowing a more accurate assessment of NMJ development, denervation, and regeneration in mouse models of neurological disease and nerve injury, which can be applied across all postnatal ages. Key features • Small muscles of the mouse hind paw, i.e., lumbrical and FDB muscles, can be rapidly dissected for whole-mount immunofluorescent analysis without the need for cryosectioning. • This protocol allows visualisation of the entire neuromuscular innervation pattern using axonal (anti-tubulin βIII), pre-synaptic (anti-synaptophysin), and post-synaptic (α-bungarotoxin) markers. • Whole-mount immunofluorescence of hind paw muscles enables assessment of developmental, degenerative, and regenerative phenotypes in young and adult mice across disease and injury models. • High-throughput analysis can be performed using NMJ-Analyser or NMJ-morph to evaluate diverse morphological features of the NMJ.

Keywords:  Acetylcholine receptor (AChR); Flexor digitorum brevis (FDB); Lumbricals; Motor neuron; Neurodegeneration; Neuromuscular disease; Neuropathology; Synapse; α-bungarotoxin (αBTX)

DOI:  https://doi.org/10.21769/BioProtoc.5315
Geroscience. 2025 May 30.

Citrinin delays muscle aging and extends lifespan in C. elegans and prevents senescence in C2C12 through SKN-1/Nrf2 activation.

Yejin Cho, Woo Jin Lee, Hee Soo Kim, Hyo-Deok Seo, Chang Hwa Jung, Jiyun Ahn, Hong-Seok Son, Jeong-Hoon Hahm.

  Sarcopenia, a condition characterized by the loss of muscle mass and function with aging, is linked to various health issues including diabetes and increased risk of falls and fractures. Currently, there is no FDA-approved treatment exists for sarcopenia. Citrinin, a natural compound present in daily dietary sources such as grains, has not been well characterized for its biological effects on muscle aging. Here, we found that citrinin exhibits beneficial effects in delaying muscle aging in both Caenorhabditis elegans (C. elegans) and mouse muscle cells (C2C12). Citrinin attenuated the decline of muscle activities in aged C. elegans, including pharyngeal pumping, body bending, maximum velocity, and locomotor abilities. It also prevented myosin protein loss in C. elegans muscle cells. Citrinin activated SKN-1 (the C. elegans ortholog of mammalian Nrf2), which mediated the prevention of myosin protein loss and the decline in muscle activities. Additionally, citrinin extended the median lifespan of C. elegans via SKN-1. Furthermore, we found that IRE-1 mediated the effects of citrinin on SKN-1 activation and that citrinin delayed aging through the IRE-1/SKN-1 pathway. However, citrinin prevented muscle aging in a UPRER (unfolded protein response of the endoplasmic reticulum) independent manner. In addition, in C2C12 cells, citrinin reduced the number of β-galactosidase-positive stained cells, prevented nuclear expansion, and decreased p21 expression under etoposide-induced senescence conditions, while also activating Nrf2. These findings suggest that citrinin is a potential candidate compound for preventing muscle aging by inducing well-conserved stress response mechanisms from C. elegans to humans. Thus, we propose that citrinin may have positive effects on promoting healthy aging in humans.

Keywords:   C. elegans ; Citrinin; IRE-1; Lifespan; Mouse muscle cells; Muscle aging; SKN-1

DOI:  https://doi.org/10.1007/s11357-025-01713-7
Phytomedicine. 2025 May 17. pii: S0944-7113(25)00489-1. [Epub ahead of print]143 156851

Cinnamic acid-GPR109A pathway improves skeletal muscle hypertrophy and metabolism.

Zewei Ma, Penglin Li, Xiaohua Feng, Yunlong Zhu, Fan Li, Guli Xu, Lina Wang, Songbo Wang, Ruifan Wu, Canjun Zhu, Ping Gao, Qingyan Jiang, Gang Shu.

   BACKGROUND: Cinnamic acid (CA), a phenylalanine metabolite found in various plants, such as Cinnamomi ramulus, a key role in regulating biological process, like proliferation, osteoblast differentiation, glucose and lipid metabolism, angiogenesis, and the activation of brown adipocytes. However, its physiological role in manipulating skeletal muscle phenotype is unclear.
PURPOSE: In this study, we summarize its amazing role in skeletal muscle hypertrophy and mitochondrial metabolism and briefly clarify the mechanical function of GPR109A/PKA pathway under those process.
METHODS: In vivo, C57BL/6 mice were subjected to acute and chronic CA supplement to investigate its function on skeletal muscle development, exercise capacity and systemic metabolism. In vitro, C2C12 cells was used to quantify protein synthesis, mitochondrial biogenesis and intracellular ATP dynamics.
RESULTS: Chronic CA supplementation effectively increased energy expenditure and significantly altered lean fat mass and gut microbiota composition in mice, while acute addition of CA enhanced the tibialis anterior muscle index, tricarboxylic acid cycle activation, and exercise capacity. Mechanically, we demonstrated that CA induces myotube hypertrophy by promoting protein synthesis in vitro. Meanwhile, the mitochondrial content and intracellular ATP level were significantly accumulated through the activation of GPR109A and its downstream PKA/CREB signalling pathway, and which is also could regulated by CA directly binding.
CONCLUSION: These results firstly reveal the critical role of CA in promoting skeletal muscle hypertrophy and mitochondrial metabolism via the GPR109A/PKA pathway, which shows experimental basic for CA to be a potential food source for improving metabolism. Most importantly form a treatment standpoint, CA could be a newly treatment for sarcopenia.

Keywords:  Akkermansia muciniphila; Cinnamic acid; GPR109A; Hypertrophy; Mitochondrion; Skeletal muscle

DOI:  https://doi.org/10.1016/j.phymed.2025.156851
Biomolecules. 2025 Apr 29. pii: 637. [Epub ahead of print]15(5):

Ngn2-Induced Differentiation of the NG108-15 Cell Line Enhances Motor Neuronal Differentiation and Neuromuscular Junction Formation.

Madeline Meli, Kristy Swiderski, Jinchao Gu, Ben Rollo, Ben Bartlett, Marissa K Caldow, Gordon S Lynch, Patrick Kwan, Huseyin Sumer, Brett Cromer.

  The neuronal progenitor NG108-15 neuroblastoma x glioma cell line proliferates indefinitely in vitro and is capable of directed differentiation into cholinergic neurons. The cell line is a robust model for investigating neuronal differentiation and function in vitro. The lineage-specific transcription factor-mediated differentiation of pluripotent stem cell lines (PSCs) leads to more rapid, efficient, and functional neurons. In this study, we tested the hypothesis that transcription factors could also drive the fate of an immortalised cell line. We first established a stable NG108-15 cell line, by piggyBac (pBac) transposition, that conditionally expresses neurogenin-2 (Ngn2), a common transcription factor for specifying neuronal fate. Following doxycycline-induction of Ngn2, we observed more rapid and efficient differentiation, and improved neurite outgrowth and viability compared with the WT cell line. Moreover, when co-cultured with C2C12 mouse myotubes, the modified NG108-15 cells resulted in significantly larger acetylcholine receptor (AChR) aggregates, suggesting enhanced neuromuscular junction (NMJ) formation. These findings describe a novel methodology for differentiating NG108-15 cells more efficiently, to enhance the usefulness of the cell line as a motor neuron model.

Keywords:  cell differentiation; cell line; motor neurons; muscle fibres; myogenesis; neuroblastoma; neuromuscular junction; neurons; skeletal muscle; transcription factors

DOI:  https://doi.org/10.3390/biom15050637
J Biol Chem. 2025 May 27. pii: S0021-9258(25)02146-5. [Epub ahead of print] 110296

Secreted EMC10 inhibits muscle GLUT4 activity and glucose uptake in mice.

Shuoshuo Jin, Wei Wu, Shan Liu, Yahao Wang, Qi Huang, Kun He, Yunzhi Ni, Kuangyang Chen, Jinya Huang, Lijie Liu, Jiarong Dai, Chongwen Zhan, Xinru Wang, Yihui Guan, Matthias Blüher, Xuanchun Wang.

  Manipulation of glucose uptake plays a critical role in muscle glucose disposal. We have shown that the secreted isoform of endoplasmic reticulum membrane protein complex subunit 10 (scEMC10) impairs glucose tolerance in mice and serum scEMC10 is positively associated with insulin resistance and hyperglycemia in humans. In this study, we attempt to investigate whether modulation of muscle glucose uptake implicates in the scEMC10-impacted glucose homeostasis. In mouse models, Emc10 gene knockout elevated, while recombinant scEMC10 treatment reduced, muscle glucose uptake and GLUT4 expression. In myoblasts, scEMC10 inhibited both GLUT4 expression and membrane translocation, and downregulated expression of genes associated with intracellular glucose metabolism. Mechanistically, scEMC10 suppressed the activation of muscle AMPK and insulin signaling cascades. Inhibition of scEMC10 via a neutralizing antibody enhanced muscle glucose uptake in mice, in parallel with heightened GLUT4 expression and membrane translocation, which accounts for an improved whole-body glucose homeostasis. In conclusion, this work identifies scEMC10 as a novel suppressor of muscle glucose uptake, and suggests inhibition of scEMC10 as a therapeutic strategy for type 2 diabetes.

Keywords:  GLUT4; glucose uptake; secreted EMC10; skeletal muscle

DOI:  https://doi.org/10.1016/j.jbc.2025.110296
Aging Cell. 2025 May 28. e70114

Intermittent Supplementation With Fisetin Improves Physical Function and Decreases Cellular Senescence in Skeletal Muscle With Aging: A Comparison to Genetic Clearance of Senescent Cells and Synthetic Senolytic Approaches.

Kevin O Murray, Sophia A Mahoney, Katelyn R Ludwig, Jill H Miyamoto-Ditmon, Nicholas S VanDongen, Nirad Banskota, Allison B Herman, Douglas R Seals, Robert T Mankowski, Matthew J Rossman, Zachary S Clayton.

  Excess cellular senescence contributes to age-related increases in frailty and reductions in skeletal muscle strength. In the present study, we determined the efficacy of oral intermittent treatment (1 week on-2 weeks off-1 week on) with the natural flavonoid senolytic fisetin to improve frailty and grip strength in old mice. Further, the effects of fisetin on physical function were evaluated in young mice. We performed bulk RNA sequencing of quadricep skeletal muscle to determine the cell senescence-related signaling pathways modulated by fisetin. We also assessed the relative effects of fisetin on frailty and grip strength with aging in comparison with two other well-established approaches for the removal of senescent cells: (1) genetic-based clearance of excess senescent cells in old p16-3MR mice, a model that allows for clearance of p16-positive (p16+) senescent cells, and (2) oral intermittent treatment with the synthetic pharmacological senolytic ABT-263 in old mice. We found that fisetin mitigated the adverse changes in frailty and grip strength with aging. Fisetin had no effects in young mice. The improvements in frailty and grip strength in old mice were accompanied by favorable modulation of the skeletal muscle transcriptome, including lower abundance of cellular senescence-related genes (e.g., Cdkn1a and Ddit4). Improvements in frailty and grip strength with fisetin were comparable to those observed with genetic-based clearance of excess p16+ senescent cells and treatment with ABT-263. Taken together, our findings provide proof-of-concept support for fisetin as a senolytic strategy to improve physical function with aging.

Keywords:  flavonoid; motor function; natural senolytic; senescence associated secretory phenotype; skeletal muscle senescence; transcriptome

DOI:  https://doi.org/10.1111/acel.70114
Sci Rep. 2025 May 30. 15(1): 19099

CD9, a novel potential biomarker of sarcopenia.

Lin Yin, Na Li, Peirong Bai, Shasha Wu, Xuena Wang, Bin Lu.

  Sarcopenia is defined as a progressive decrease in skeletal muscle mass and strength due to ageing, and is associated with adverse outcomes such as falls, fractures, and physical disability, leading to increased healthcare expenditures and mortality risks. Although sarcopenia has recently become a major challenge, there are currently no effective interventions or drugs marketed for sarcopenia. Therefore, new biomarkers for early diagnosis and targeted drugs for the treatment of sarcopenia are urgently needed. In the present research, transcriptomics and proteomics analyses were combined and experiments at the transcriptional and protein levels were conducted to identify key genes and molecular mechanisms underlying sarcopenia in senescence-accelerated mouse prone 8 (SAM-P8) mice, followed by molecular docking to predict targeted drugs. The combined omics analysis identified 8 key genes, while the experiments verified that only CD9 significantly decreased in sarcopenia. The gene set enrichment analysis (GSEA) results suggested that CD9 involved in ATP biosynthesis, mitochondrial biogenesis, and oxidative phosphorylation. Besides, dapoxetine, levomilnacipran, and milnacipran were predicted to target CD9 through molecular docking. Our study reported for the first time that CD9 is a novel potential biomarker of sarcopenia, and targeting CD9 may be a new idea for the development of therapeutic drugs for sarcopenia.

Keywords:  Biomarker; CD9; Proteomics; Sarcopenia; Transcriptomics

DOI:  https://doi.org/10.1038/s41598-025-04331-7
Front Pharmacol. 2025 ;16 1619972

Editorial: Emerging trends in cardiac and skeletal muscle pharmacotherapy.

Young Hoon Son, Ivan Vechetti, Dawn Katrina Coletta.



Keywords:  cancer cachexia; cardiotoxicity; muscle pharmacology; therapeutic interventions; translational medicine

DOI:  https://doi.org/10.3389/fphar.2025.1619972
BMC Musculoskelet Disord. 2025 May 27. 26(1): 520

Potential effect of Irisin on sarcopenia: a systematic review.

Yixiao Chen, Min Qian, Feng Gao, Guoqing Li, Kangzu Peng, Qingnan Sun, Yifei Sun, Gang Liu, Yufeng Ge, Minghui Yang, Xinbao Wu.

   OBJECTIVE: Sarcopenia, a progressive musculoskeletal disorder associated with aging, is characterized by the deterioration of muscle mass, strength, and physical performance. This condition significantly increases the risk of debilitating consequences including functional impairment, diminished life quality, and increased mortality. With the progress of aging, it will affect a large number of people in the world and bring many problems. Despite its clinical significance, there are no medicine used to treatment sarcopenia by FDA approval in clinical. This systematic review synthesizes current evidence on the diagnostic and therapeutic potential of irisin-a myokine induced by exercise-in sarcopenia, aiming to address two key questions: (1) Can irisin serve as a reliable biomarker for sarcopenia diagnosis? (2) Does irisin hold promise as a therapeutic agent for sarcopenia management?
METHODS: A comprehensive literature search was conducted across multiple databases (Web of Science, PubMed, Cochrane Library, and Embase) to examine the relationship between irisin and sarcopenia. Eligible studies meeting our inclusion criteria underwent rigorous quality assessment.
RESULT: 364 studies were identified, of which only 21 met the inclusion criteria-12 involving human studies and 9 involving animal and cell experiments. In human studies, irisin may serve as a potential diagnostic marker for sarcopenia in the elderly and postmenopausal women. In addition, as a myokine of exercise induced, increased circulating levels of irisin may enhanced skeletal muscle mass. Moreover, animal and cellular experiments suggest that increased levels of irisin help improve muscle mass.
CONCLUSION: In conclusion, this review indicates that irisin has potential therapeutic effects for sarcopenia and may become a promising treatment for sarcopenia in the future. However, there is currently a lack of high-quality studies on the use of irisin in treating sarcopenia, and the relevant mechanisms of action are not yet clear. Therefore, more studies are needed to clarify the relationship between irisin and sarcopenia in the future.

Keywords:  Irisin; Sarcopenia; Systematic review; Treatment

DOI:  https://doi.org/10.1186/s12891-025-08767-w
Acta Neuropathol Commun. 2025 May 24. 13(1): 115

Evaluation of aggrephagy markers in myofibrillar myopathies.

Eliana Iannibelli, Alessandra Ruggieri, Antonello Maruotti, Franco Salerno, Marta Cheli, Alessandra Carnazzi, Lucia Nicolini De Gaetano, Giorgia Riolo, Sara Bortolani, Pietro Riguzzi, Sara Vianello, Gioia Merlonghi, Luca Bello, Matteo Garibaldi, Massimiliano Filosto, Stefano Carlo Previtali, Giorgio Tasca, Gaetano Vattemi, Paola Tonin, Elena Pegoraro, Sara Gibertini, Lorenzo Maggi.

  Myofibrillar Myopathies (MFMs) are a growing group of muscular disorders genetically determined, whose diagnosis is based on histological features as myofibrillar degeneration, Z-disk disorganization and protein aggregates' accumulation. Protein aggregates that do not fit the proteasome's narrow pore are targeted for removal via a specialized form of autophagy, called aggrephagy. Our study aims to investigate the potential pathogenic role of aggrephagy in 52 muscle samples from an Italian MFM multicentric cohort. We measured, the percentage of positive areas of key aggrephagy proteins by immunofluorescence staining, of sequestosome 1 (p62/SQSTM1), Neighbor of BRCA1 Gene 1 (NBR1), and ubiquitinated proteins (FK2) in 11 DES-, 6 DNAJB6-, 5 FLNC-, 18 MYOT- and 12 TTN-mutated patients. We showed that all aggrephagy markers are increased in these patients, regardless of the mutated genes, suggesting a possible common pathomechanism; no positive signal was found in healthy, age-matched controls. We analyzed the association between positivity levels of these markers, measured as percentage of positive areas, and selected clinical features utilizing generalized linear mixed models with gamma distribution as the probability model and center-specific random effects to better capture possible heterogeneity across participating centers. Our findings indicate significant associations between levels of p62, NBR1, and FK2 with age at biopsy (p62 and NBR1 p-values < 0.001, FK2 p-value < 0.05), age of onset (p62 and NBR1 p-values < 0.001, FK2 p-value < 0.01) and disease severity through Walton & Gardner-Medwin (WGM) score at biopsy (all p-values < 0.001) and at the last visit (all p-values < 0.05). Noteworthy, the aggrephagic pathway is mostly activated in MYOT-mutated patients compared to the other subgroups. Moreover, the association between aggrephagy and WGM score at biopsy is stronger in this subgroup. Overall, our study emphasizes the role of aggrephagy in MFMs across all patients, and its association with specific clinical parameters.

Keywords:  Clinical association; Genetic rare diseases; Myofibrillar alterations; Protein aggregation

DOI:  https://doi.org/10.1186/s40478-025-02041-9