White J D, Scaffidi A, Davies M, McGeachie J, Rudnicki M A, Grounds M D
Department of Anatomy and Human Biology, the University of Western Australia, Nedlands, Western Australia.
J Histochem Cytochem. 2000 Nov;48(11):1531-44. doi: 10.1177/002215540004801110.
We compared the time course of myogenic events in vivo in regenerating whole muscle grafts in MyoD(-/-) and control BALB/c adult mice using immunohistochemistry and electron microscopy. Immunohistochemistry with antibodies to desmin and myosin revealed a striking delay by about 3 days in the formation of myotubes in MyoD(-/-) autografts compared with BALB/c mice. However, myotube formation was not prevented, and autografts in both strains appeared similar by 8 days. Electron microscopy confirmed myotube formation in 8- but not 5-day MyoD(-/-) grafts. This pattern was not influenced by cross-transplantation experiments between strains examined at 5 days. Antibodies to proliferating cell nuclear antigen demonstrated an elevated level of replication by MyoD(-/-) myoblasts in autografts, and replication was sustained for about 3 days compared with controls. These data indicate that the delay in the onset of differentiation and hence fusion is related to extended proliferation of the MyoD(-/-) myoblasts. Overall, although muscle regeneration was delayed it was not impaired in MyoD(-/-) mice in this model.
我们使用免疫组织化学和电子显微镜，比较了MyoD基因敲除小鼠和对照BALB/c成年小鼠体内再生全肌移植物中肌源性事件的时间进程。用结蛋白和肌球蛋白抗体进行免疫组织化学分析显示，与BALB/c小鼠相比，MyoD基因敲除小鼠的自体移植物中肌管形成显著延迟约3天。然而，肌管形成并未被阻止，两种品系的自体移植物在8天时看起来相似。电子显微镜证实8天龄而非5天龄的MyoD基因敲除移植物中有肌管形成。这种模式不受5天时检测的品系间交叉移植实验的影响。增殖细胞核抗原抗体显示，MyoD基因敲除小鼠自体移植物中的成肌细胞复制水平升高，与对照组相比，复制持续约3天。这些数据表明，分化起始进而融合的延迟与MyoD基因敲除成肌细胞的增殖延长有关。总体而言，在该模型中，尽管MyoD基因敲除小鼠的肌肉再生延迟，但并未受损。
