It is proposed that the age-associated reduction in LANCL1-AS1 contributes to impaired mitochondrial function and reduced myogenic capacity in aging skeletal muscle.
Abstract
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.
A spatial transcriptomic atlas of skeletal muscle from young and aged mice is presented, resolving transcriptional reprogramming across fiber types and tissue compartments and revealing alterations in sarcomeric organization, excitation-contraction coupling, oxidative stress responses, and fiber type-specific metabolic rewiring.
Veronica Ruggieri, Andrea Bracaglia, Lorenza Esposito et al.· iScience· 0 citations
Sarcopenia is characterized by the progressive loss of skeletal muscle mass and strength, accompanied by impaired regenerative capacity. This study examined age-related changes in skeletal muscle regeneration and the associated expression of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and myogenin (MyoG). Male C57BL/6 mice aged 3, 13, and 23 months were subjected to barium chloride (BaCl2)-induced tibialis anterior muscle injury. In parallel, C2C12 cells were exposed to repeated low-dose hydrogen peroxide (H2O2) to induce senescence-associated changes under oxidative stress, and the effect of the TWEAK inhibitor L524 was evaluated. Muscle mass and grip strength showed age-dependent declines. Following BaCl2 injury, MyoD expression was induced similarly across age groups, whereas MyoG and embryonic myosin heavy chain expression significantly decreased with advancing age. TWEAK expression increased in injured muscle with age, while p-4E-BP1 showed no clear age-dependent change. In C2C12 cells, repeated H2O2 exposure at 100 μM, which maintained cell viability above 90%, induced senescence-associated changes, reduced myotube formation, increased TWEAK expression, and decreased MyoG expression, whereas treatment with the TWEAK inhibitor L524 attenuated the H2O2-associated reduction in MyoG expression. Collectively, these findings suggest that TWEAK signaling may be associated with oxidative stress and age-related impairments in muscle regeneration.
Jin-Hwa Kim, Hyun-Tae Kim, Jeong-won Kim et al.· Experimental Gerontology· 0 citations
Skeletal muscle stem cells (MuSCs) give rise to a fusogenic cell population that provide new myonuclei to muscle fibers. Myonuclear functional heterogeneity has recently become appreciated, but the terminal identity of MuSC-Derived myonuclei remains undefined. We performed single-nucleus RNA-sequencing of myonuclei in Adult and Aged muscle to define MuSC-Derived and resident myonuclear responses to mechanical overload (MOV), which induces a hypertrophic stimulus. We found a MuSC-dependent induction of a youthful transcriptional signature in resident myonuclei after MOV in Aged muscle. Age determined terminal transcriptional states of MuSC-Derived myonuclei toward MTJ in Adult, NMJ in Aged, and muscle spindles in both ages. Microtubule-remodeling genes, Macf1, Map1b, and Nav3, along with the transcription factor Runx1, identified this post-fusion specialization with greater expression of these genes in Adult than in Aged MuSC-Derived myonuclei. In-silico transcription factor KO screen identified Runx1 as a regulator of post-fusion specialization and Esrrg as a driver of spindle (intrafusal) MuSC-Derived myonuclear maturation. By defining the age-associated fate of MuSC fusion to muscle fibers, we provide potential targets for modulating muscle plasticity. Highlights MuSC presence creates a more youthful myonuclear transcriptional signature in Aged muscle with mechanical overload (MOV). MOV-Responsive myonuclei depend on MuSCs in Aged but not Adult skeletal muscle MuSC-Derived myonuclei transcriptionally specialize to support the myotendinous junction in Adult muscle, the neuromuscular junction in Aged muscle, and muscle spindle (intrafusal) fibers in both ages. Pseudotime predicts Runx1 may function as a master regulator of MuSC-Derived myonuclear specialization in response to MOV.
Nicholas T. Thomas, Jensen Goh, Kevin A. Murach et al.· bioRxiv· 0 citations
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.
Junjie Xu, Shuning Tang, Haiyan Xie et al.· Biochemical and Biophysical...· 0 citations
Skeletal muscle undergoes a progressive decline in mass and function with aging, a condition that in its extreme form is known as sarcopenia. This is driven by complex cellular and molecular alterations, such as shifts in myonucleus composition, increased fibrosis, and fat or immune cell infiltration. Despite extensive research, effective therapeutic interventions for sarcopenia remain limited. Recent advances in single-cell omics technologies have begun to unravel the cellular and molecular heterogeneity of mouse and human skeletal muscle across the lifespan, identifying age-enriched cell states and dynamic transcriptional changes. However, epigenetic regulation during skeletal muscle aging is less well characterized. To help address this gap, we performed single-nucleus Assay for Transposase-Accessible Chromatin using sequencing (snATAC-seq) on skeletal muscle from young adult and aged male mice, generating chromatin accessibility profiles from over 43,000 nuclei. Among other findings, our analyses reveal an age-enriched pro-atrophy subpopulation of type IIb myonuclei marked by increased chromatin accessibility at the Ampd3 locus. Furthermore, we delineate the epigenetic mechanisms underlying the transition of healthy type IIb myonuclei into Ampd3+ myonuclei, revealing key chromatin remodeling events that drive this phenotypic shift. Moreover, by integrating with an existing single-nucleus RNA sequencing dataset of the same anatomical origin, we identified thousands of cell-type-specific cis-regulatory elements related to aging programs. Within these elements, we observed a broad depletion of binding motifs for transcription factors with roles in cellular identity and muscle regeneration, concomitant with the gain of stress-responsive transcription factors. Our work helps understand the epigenetic events underlying mammalian skeletal muscle aging.
J. An, Guang-Shun Lai, Jing Zuo et al.· The FEBS Journal· 0 citations
Dysregulation of α-KG and L-2HG drives diabetic muscle fibrosis by disrupting TET2-dependent DNA hydroxymethylation and FAP division symmetry, supporting a TET2-dependent mechanism underlying the epigenetic effects of α-KG.
Zhou-Jie Tong, Yihui Li, Ming Song et al.· Metabolism: Clinical and Exp...· 1 citation
