Skeletal muscle is a dynamic tissue with two unique abilities; one is its excellent regenerative ability, due to the activity of skeletal muscle-resident stem cells named muscle satellite cells (MuSCs); and the other is the adaptation of myofiber size in response to external stimulation, intrinsic factors, or physical activity, which is known as plasticity. Low physical activity and some disease conditions lead to the reduction of myofiber size, called atrophy, whereas hypertrophy refers to the increase in myofiber size induced by high physical activity or anabolic hormones/drugs. MuSCs are essential for generating new myofibers during regeneration and the increase in new myonuclei during hypertrophy; however, there has been little investigation of the molecular mechanisms underlying MuSC activation, proliferation, and differentiation during hypertrophy compared to those of regeneration. One reason is that 'degenerative damage' to myofibers during muscle injury or upon hypertrophy (especially overloaded muscle) is believed to trigger similar activation/proliferation of MuSCs. However, evidence suggests that degenerative damage of myofibers is not necessary for MuSC activation/proliferation during hypertrophy. When considering MuSC-based therapy for atrophy, including sarcopenia, it will be indispensable to elucidate MuSC behaviors in muscles that exhibit non-degenerative damage, because degenerated myofibers are not present in the atrophied muscles. In this review, we summarize recent findings concerning the relationship between MuSCs and hypertrophy, and discuss what remains to be discovered to inform the development and application of relevant treatments for muscle atrophy.

中文翻译：

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损伤和处理在肌肉肥大中的作用：肌肉干细胞在再生和肥大中的不同行为。

骨骼肌是一种具有两种独特能力的动态组织。一种是由于骨骼肌驻留干细胞称为肌肉卫星细胞（MuSCs）的活性而具有出色的再生能力；另一个是肌纤维大小对外界刺激，内在因素或身体活动的适应，这就是可塑性。低体力活动和某些疾病状况导致肌纤维尺寸减少，称为萎缩，而肥大是指由于高体力活动或合成代谢激素/药物引起的肌纤维尺寸增加。MuSC对再生过程中产生新的肌纤维和肥大过程中新的肌核的增加至关重要。然而，关于MuSC活化，增殖，与再生相比，肥大过程中的分化和分化。原因之一是，在肌肉损伤或肥大（尤其是肌肉超负荷）期间，肌纤维的“变性损伤”被认为会触发类似的MuSCs活化/增殖。但是，有证据表明，肥大过程中MuSC激活/增殖不需要肌纤维的变性损伤。当考虑基于MuSC的萎缩疗法（包括肌肉减少症）时，阐明表现出非变性损伤的肌肉中的MuSC行为将是必不可少的，因为萎缩的肌肉中不存在变性的肌纤维。在这篇综述中，我们总结了有关MuSC与肥大之间关系的最新发现，