Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
Department of Sport and Exercise Sciences, Musculoskeletal Science and Sport Medicine Research Centre, Institute of Sport, Manchester Metropolitan University, Manchester, UK.
Geroscience. 2024 Apr;46(2):1843-1859. doi: 10.1007/s11357-023-00929-9. Epub 2023 Sep 26.
As we age, the ability to regenerate and repair skeletal muscle damage declines, partially due to increasing dysfunction of muscle resident stem cells-satellite cells (SC). Recent evidence implicates cellular senescence, which is the irreversible arrest of proliferation, as a potentiator of SC impairment during aging. However, little is known about the role of senescence in SC, and there is a large discrepancy in senescence classification within skeletal muscle. The purpose of this study was to develop a model of senescence in skeletal muscle myoblasts and identify how common senescence-associated biomarkers respond. Low-passage CC myoblasts were treated with bleomycin or vehicle and then evaluated for cytological and molecular senescence markers, proliferation status, cell cycle kinetics, and differentiation potential. Bleomycin treatment caused double-stranded DNA breaks, which upregulated p21 mRNA and protein, potentially through NF-κB and senescence-associated super enhancer (SASE) signaling (p < 0.01). Consequently, cell proliferation was abruptly halted due to G2/M-phase arrest (p < 0.01). Bleomycin-treated myoblasts displayed greater senescence-associated β-galactosidase staining (p < 0.01), which increased over several days. These myoblasts remained senescent following 6 days of differentiation and had significant impairments in myotube formation (p < 0.01). Furthermore, our results show that senescence can be maintained despite the lack of p16 gene expression in CC myoblasts. In conclusion, bleomycin treatment provides a valid model of damage-induced senescence that was associated with elevated p21, reduced myoblast proliferation, and aberrant cell cycle kinetics, while confirming that a multi-marker approach is needed for the accurate classification of senescence within skeletal muscle.
随着年龄的增长，骨骼肌肉损伤的再生和修复能力下降，部分原因是肌肉驻留干细胞-卫星细胞（SC）的功能逐渐失调。最近的证据表明，细胞衰老，即增殖的不可逆停滞，是衰老过程中 SC 损伤的增强因素。然而，人们对衰老在 SC 中的作用知之甚少，而且骨骼肌肉中的衰老分类存在很大差异。本研究的目的是建立骨骼肌肉成肌细胞衰老模型，并确定常见的衰老相关生物标志物的反应。将低传代 CC 成肌细胞用博来霉素或载体处理，然后评估其细胞学和分子衰老标志物、增殖状态、细胞周期动力学和分化潜能。博来霉素处理会导致双链 DNA 断裂，从而上调 p21mRNA 和蛋白，这可能是通过 NF-κB 和衰老相关超级增强子（SASE）信号通路（p < 0.01）。因此，由于 G2/M 期阻滞（p < 0.01），细胞增殖突然停止。博来霉素处理的成肌细胞显示出更高的衰老相关β-半乳糖苷酶染色（p < 0.01），这种染色会在几天内增加。这些成肌细胞在分化 6 天后仍保持衰老状态，并且在肌管形成方面存在严重缺陷（p < 0.01）。此外，我们的结果表明，即使在 CC 成肌细胞中缺乏 p16 基因表达的情况下，衰老也可以维持。总之，博来霉素处理提供了一种有效的损伤诱导衰老模型，与升高的 p21、成肌细胞增殖减少和异常的细胞周期动力学相关，同时证实需要采用多标志物方法对骨骼肌肉中的衰老进行准确分类。
