Creuzet S, Lescaudron L, Li Z, Fontaine-Pérus J
Faculté des Sciences et des Techniques, Université de Nantes, Nantes Cedex 03, 44322, France.
Exp Cell Res. 1998 Sep 15;243(2):241-53. doi: 10.1006/excr.1998.4100.
Although satellite cell differentiation is involved in postnatal myogenesis from growth to posttrauma regeneration, the early stages of this process remain unclear. This study investigated pHuDes-nls-lacZ transgene activity, as revealed by X-gal staining and the accumulation of MyoD, myogenin, endogenous desmin, and myosin, in order to determine whether satellite cells share the same activation program during growth and regeneration. After birth, skeletal myonuclei in which myogenin expression was limited were briefly characterized by transgene activity. Satellite cells were only evidenced by MyoD and slow myosin accumulation, but failed to initiate transgene expression. After freeze trauma, satellite cell activation led to MyoD, myogenin, and desmin expression. Subsequently, when myosin expression occurred, transgene activation was apparent in regenerating structures, with more intense X-gal staining in mononucleated cells than regenerating myotubes. After the second week posttrauma, only desmin and myogenin expression were maintained in regenerating structures. In culture, the behavior of satellite cells showed that desmin expression was committed before transgene activation occurred, i.e., concurrently with MyoD, myogenin, myosin expression, and the first fusion events. Quantitative analysis confirmed the discrepancy between endogenous desmin and transgene expression and demonstrated the close correlation between transgene activation and the fusion index. Our results strongly suggest that satellite cells promote distinct pathways of myogenic response during growth and regeneration.
尽管卫星细胞分化参与了从生长到创伤后再生的出生后肌生成过程，但该过程的早期阶段仍不清楚。本研究通过X-gal染色以及MyoD、肌细胞生成素、内源性结蛋白和肌球蛋白的积累来研究pHuDes-nls-lacZ转基因活性，以确定卫星细胞在生长和再生过程中是否共享相同的激活程序。出生后，肌细胞生成素表达受限的骨骼肌细胞核通过转基因活性进行了简要表征。卫星细胞仅通过MyoD和慢肌球蛋白的积累得以证实，但未能启动转基因表达。冷冻创伤后，卫星细胞激活导致MyoD、肌细胞生成素和结蛋白表达。随后，当肌球蛋白表达出现时，转基因激活在再生结构中明显可见，单核细胞中的X-gal染色比再生肌管更强烈。创伤后第二周后，再生结构中仅维持结蛋白和肌细胞生成素表达。在培养中，卫星细胞的行为表明结蛋白表达在转基因激活之前就已确定，即与MyoD、肌细胞生成素、肌球蛋白表达以及首次融合事件同时发生。定量分析证实了内源性结蛋白与转基因表达之间的差异，并证明了转基因激活与融合指数之间的密切相关性。我们的结果强烈表明，卫星细胞在生长和再生过程中促进了不同的肌生成反应途径。
