Aug 2026· Biochemical and Biophysical Research Communications - BBRC· Vol 834, pp.
154470
· 0 citations· 34 references
Medicine
Abstract
Although UFMylation is implicated in skeletal muscle development, the role of its E3 ligase, ubiquitin-fold modifier 1 ligase 1 (UFL1), in bovine muscle and myofiber type determination is unclear. We profiled UFL1 expression in four muscles (biceps femoris (BF), longissimus dorsi (LD), trapezius (TR), psoas major (PM)) from 18-month-old Simmental and Angus bulls via histology, RT-qPCR, western blotting, and immunofluorescence. UFL1 mRNA and protein were significantly higher in fast-twitch muscles (LD, BF) than in slow-twitch PM. UFL1 localized to sarcolemma and sarcoplasmic reticulum, co-localized with MYHC-Fast in LD, and correlated positively with MYHC-Fast. Oxidative PM showed higher SDH/MDH activities, lower LDH activity, and greater lipid deposition than glycolytic LD. UFL1 correlated negatively with PLIN2. LD exhibited lower ACC1, FASN, PPARα, and CPT1A levels than PM. Collectively, UFL1 is specifically expressed in fast-twitch fibers, associates with lipid metabolic reprogramming, suggesting a role in muscle development and meat quality. This study identifies UFL1 as a novel candidate regulator of myofiber type determination in beef cattle.
Regeneration of skeletal muscle preserves muscle mass and function, which decline with age. Here, we sought to identify long noncoding (lnc)RNAs involved in skeletal muscle myogenesis and potentially relevant to muscle aging. Cross-sectional analysis of skeletal muscle transcriptomes from healthy 22-through 89-year-old individuals revealed lncRNA LANCL1-AS1 among the top declining transcripts. Conversely, LANCL1-AS1 increased robustly during skeletal myogenesis and promoted myogenic differentiation in culture. Affinity pulldown by ChIRP followed by mass spectrometry revealed that LANCL1-AS1 associated with the mitochondrial protein LRPPRC, enhancing the formation of the chaperone complex LRPPRC-SLIRP, which maintains longer poly(A) tails of mitochondrial (mt-)mRNAs and stabilizes mt-mRNAs. Importantly, while myoblasts from old rhesus monkey muscle expressed lower levels of LANCL1-AS1 and mt-mRNAs, and displayed lower mitochondrial activity than young monkey myoblasts, overexpressing LANCL1-AS1 in old myoblasts restored mitochondrial activity and myogenesis. We propose that the age-associated reduction in LANCL1-AS1 contributes to impaired mitochondrial function and reduced myogenic capacity in aging skeletal muscle.
Jen-Hao Yang, Elizabeth K. Izydore, K. Mazan-Mamczarz et al.· bioRxiv· 0 citations
Sarcopenia is characterized by progressive loss of skeletal muscle mass and function and is a major contributor to frailty, disability, and mortality in older adults. Store-operated calcium entry (SOCE) is a crucial regulator of skeletal muscle calcium homeostasis, and impaired SOCE has been linked to age-related muscle weakness. Here, we identify the synaptophysin family member synaptophysin-like protein 2, also known as mitsugumin 29 (MG29; encoded by the human gene SYPL2 and the mouse ortholog Mg29), as a key organizer of triad membrane cholesterol and lipid signaling required for normal SOCE during aging. Using Mg29−/− mice as a model of accelerated sarcopenia, together with RNA interference against Mg29 in adult muscle and primary myotubes, we quantified changes in muscle morphology, contractile function, SOCE activity, and targeted lipidomic profiles. Reduced MG29 expression led to decreased muscle fiber cross-sectional area, reduced specific force, blunted SOCE, and marked alterations in membrane cholesterol content and fatty acid-derived lipid mediators. Cholesterol depletion by methyl-β-cyclodextrin in wild-type myotubes produced SOCE defects similar to those observed in aged wild-type and young Mg29−/− muscles, indicating that MG29-dependent maintenance of membrane cholesterol is required for normal SOCE. Acute Mg29 knockdown also altered myogenic differentiation, the expression of calcium-handling and stress-response genes, and the release and consumption of specific polyunsaturated fatty acid-derived lipid mediators. Together, these findings identify MG29 as a critical regulator of SOCE and lipid signaling in skeletal muscle and suggest that its age-related decline contributes to sarcopenia by disrupting triad membrane organization and excitation–contraction coupling.
Kamal Awad, Jian Huang, Marian N. Aziz et al.· Biomolecules· 0 citations
Mitochondrial dysfunction is an important cause of sarcopenia, and TWEAK/Fn14, as one of the major muscle wasting cytokines, its role in the development of sarcopenia by regulating mitochondrial biogenesis remains unclear. Expression of TWEAK in old and young mice was both detected. TWEAK was silenced in C2C12 myocytes using lentiviral vectors. Immunofluorescence, western blot, real-time polymerase chain reaction (RT-PCR), and ELISA were enrolled to analyze the effects of TWEAK on myotube size, mitochondrial content, mitochondrial ROS, and inflammatory factors. Additionally, aged mice received two injections of AAV9 vectors at 15 and 17 months of age. Upon reaching 18 months of age, the effects of TWEAK knockdown on grip strength, muscle mass, and gastrocnemius muscle indices were evaluated. TWEAK/Fn14 expression was significantly increased in old mice (
p
< 0.001). Compared with young controls, old mice exhibited a significant decrease in grip strength (
p
< 0.001) and a significant increase in lean mass (
p
< 0.05), whereas no significant difference was observed in fat content. In DEX-treated C2C12 myotubes, TWEAK knockdown significantly increased myotube diameter, enhanced ATP content and mitochondrial quantity, upregulated protein expression of SIRT1, PGC-1α, and p-AMPK, and inhibited mitochondrial ROS, Ca
2+
levels, p-p38 expression, and the secretion of inflammatory cytokines (TNF-α, IL-1β, IL-6, and iNOS). In aged mice, TWEAK knockdown did not significantly alter forelimb grip strength or lean mass, but significantly increased fat mass (
p
< 0.05). Mechanistically, TWEAK knockdown promoted AMPK signaling, inhibited p38 MAPK activation, enhanced mitochondrial biogenesis, and reduced serum levels of IL-1β, IL-6, and iNOS (
p
< 0.05), whereas serum TNF-α levels showed no significant difference. TWEAK knockdown attenuates age-related skeletal muscle mass loss and improves mitochondrial biogenesis in skeletal muscle, accompanied by modulated inflammatory factor release and altered AMPK-p38 MAPK signaling activity. However, no significant improvement in forelimb grip strength was observed in the in vivo experiment. These findings indicate that TWEAK suppression may represent a promising strategy for preserving muscle mass and metabolic homeostasis during aging, though its capacity to fully restore functional capacity requires further investigation.
Zhuoya Maimaitiwusiman, Saiyare Xuekelati, Anyan Wang et al.· Scientific Reports· 0 citations
Introduction Skeletal muscle differentiation in the C2C12 myoblast model requires extensive mitochondrial remodeling to meet rising bioenergetic demands through coordinated changes in biogenesis, dynamics, and respiratory adaptation. Urolithin A (UA), a gut microbiota-derived metabolite of ellagitannins, improves mitochondrial health, but its role in late-stage myogenic differentiation remains unclear. Methods C2C12 myotubes were treated with UA (2 μM) for 72 h during late-stage differentiation (days 3–6). Mitochondrial signaling, respiratory capacity, myogenic morphology, and ultrastructure were assessed by Western blot, high-resolution respirometry, hematoxylin–eosin staining, and transmission electron microscopy. Results UA was non-cytotoxic and increased AMPKα phosphorylation and PGC-1α expression, whereas TOM20, MFN2, and OPA1 were unchanged. Mitophagy/autophagy-related markers (p-ULK1, p62, BNIP3L/NIX, LC3-II/I) were not altered, indicating no detectable changes in steady-state autophagy under the conditions tested. UA selectively increased OXPHOS Complex I and II abundance and enhanced maximal uncoupled respiration, and was associated with increased myotube diameter and myogenic marker abundance. No overt ultrastructural differences were observed by electron microscopy. Discussion These findings suggest that UA promotes mitochondrial functional adaptation during myogenic differentiation, with accompanying changes in myogenic phenotype, without clear evidence of altered steady-state mitophagy/autophagy markers or mitochondrial morphology.
R. Vargas-Foitzick, Diego Irribarra-Tapia, M. Valero-Breton et al.· Frontiers in Cell and Develo...· 1 citation
Ordered proliferation of skeletal muscle myoblasts is essential for muscle development and repair and requires coordinated metabolic remodeling. Acyl-CoA synthetase long-chain family member 3 (ACSL3) activates long-chain fatty acids and thereby supports lipid metabolic flux, but the post-translational mechanisms regulating ACSL3 in myoblasts remain incompletely defined. UFMylation is a ubiquitin-like post-translational modification mediated by a cascade that includes the E2-conjugating enzyme UFC1. Here, we investigated whether UFC1 regulates ACSL3 abundance and lipid metabolism in C2C12 myoblasts and primary mouse skeletal muscle myoblasts. UFC1 knockout or knockdown reduced ACSL3 protein abundance, decreased myoblast proliferation, and lowered cellular neutral and polar lipid signals. Transcriptomic gene set enrichment analysis further indicated suppression of pathways related to unsaturated fatty acid biosynthesis and fatty acid metabolism after UFC1 loss. Co-immunoprecipitation showed an association between UFC1 and ACSL3, and endogenous immunoprecipitation detected a UFC1-dependent UFM1 signal on ACSL3. Cycloheximide chase assays indicated accelerated ACSL3 degradation in UFC1-deficient cells, whereas the proteasome inhibitor MG132 partially restored ACSL3 protein abundance. Overexpression of ACSL3 alleviated lipid metabolic defects and partially rescued proliferation in UFC1-deficient myoblasts. These findings suggest that UFC1 contributes to ACSL3 protein abundance, probably through UFMylation-associated suppression of proteasomal degradation, thereby supporting lipid homeostasis and proliferation in skeletal muscle myoblasts.
Mali Guo, Junjie Xu, Haiyan Xie et al.· Biochemical and Biophysical...· 0 citations
Summary Sarcopenia, the age-related decline in skeletal muscle mass and function, profoundly affects skeletal muscle structure and performance. We present a spatial transcriptomic atlas of skeletal muscle from young and aged mice, resolving transcriptional reprogramming across fiber types and tissue compartments. Our analyses reveal alterations in sarcomeric organization, excitation-contraction coupling, oxidative stress responses, and fiber type-specific metabolic rewiring. Conserved molecular signatures across muscles and species highlight Car3 as a potential biomarker of sarcopenia. We also uncover a selective downregulation of polyamine biosynthetic enzymes, leading to reduced spermidine levels in aged muscle. This decline affects muscle-resident populations, as limiting polyamine metabolic flux in both murine and human fibro-adipogenic progenitors (hFAPs) induces aging-like features, including myofibroblast differentiation, extracellular matrix dysregulation, and impaired ability to support myogenesis. Together, our findings reveal spatially organized, fiber type-specific, and polyamine-linked mechanisms of muscle aging and position the polyamine pathway as a promising therapeutic target.
Veronica Ruggieri, Andrea Bracaglia, Lorenza Esposito et al.· iScience· 0 citations