Viggars Mark R, Owens Daniel J, Stewart Claire, Coirault Catherine, Mackey Abigail L, Jarvis Jonathan C
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.
Department of Physiology and Aging, University of Florida, Gainesville, Florida.
Am J Physiol Cell Physiol. 2023 Jan 1;324(1):C85-C97. doi: 10.1152/ajpcell.00285.2022. Epub 2022 Nov 21.
Myonuclei transcriptionally regulate muscle fibers during homeostasis and adaptation to exercise. Their subcellular location and quantity are important when characterizing phenotypes of myopathies, the effect of treatments, and understanding the roles of satellite cells in muscle adaptation and muscle "memory." Difficulties arise in identifying myonuclei due to their proximity to the sarcolemma and closely residing interstitial cell neighbors. We aimed to determine to what extent (pericentriolar material-1) PCM1 is a specific marker of myonuclei in vitro and in vivo. Single isolated myofibers and cross sections from mice and humans were studied from several models including wild-type and Lamin A/C mutant mice after functional overload and damage and recovery in humans following forced eccentric contractions. Fibers were immunolabeled for PCM1, Pax7, and DNA. C2C12 myoblasts were also studied to investigate changes in PCM1 localization during myogenesis. PCM1 was detected at not only the nuclear envelope of myonuclei in mature myofibers and in newly formed myotubes but also centrosomes in proliferating myogenic precursors, which may or may not fuse to join the myofiber syncytium. PCM1 was also detected in nonmyogenic nuclei near the sarcolemma, especially in regenerating areas of the mouse and damaged human muscle. Although PCM1 is not completely specific to myonuclei, the impact that PCM1+ macrophages and interstitial cells have on myonuclei counts would be small in healthy muscle. PCM1 may prove useful as a marker of satellite cell dynamics due to the distinct change in localization during differentiation, revealing satellite cells in their quiescent (PCM1-), proliferating (PCM1+ centrosome), and prefusion states (PCM1+ nuclear envelope).
在稳态和运动适应过程中，肌核通过转录调控肌纤维。在表征肌病表型、治疗效果以及理解卫星细胞在肌肉适应和肌肉“记忆”中的作用时，它们的亚细胞定位和数量很重要。由于肌核靠近肌膜且与相邻的间质细胞紧密相邻，因此在识别肌核时会遇到困难。我们旨在确定在体外和体内，（中心粒周物质-1）PCM1在多大程度上是肌核的特异性标志物。我们研究了来自几种模型的小鼠和人类的单个分离肌纤维和横截面，包括野生型和Lamin A/C突变小鼠在功能过载和损伤后的情况，以及人类在强迫离心收缩后的损伤和恢复情况。对纤维进行PCM1、Pax7和DNA的免疫标记。还研究了C2C12成肌细胞，以研究成肌过程中PCM1定位的变化。在成熟肌纤维和新形成的肌管中的肌核的核膜上，以及增殖的成肌前体细胞的中心体中都检测到了PCM1，这些前体细胞可能会融合或不会融合以加入肌纤维合胞体。在肌膜附近的非肌源性核中也检测到了PCM1，尤其是在小鼠再生区域和受损的人类肌肉中。尽管PCM1并非完全特异性地存在于肌核中，但在健康肌肉中，PCM1+巨噬细胞和间质细胞对肌核计数的影响可能很小。由于PCM1在分化过程中的定位会发生明显变化，因此它可能被证明是卫星细胞动态变化的有用标志物，揭示了卫星细胞的静止（PCM1-）、增殖（PCM1+中心体）和预融合状态（PCM1+核膜）。
