Berthier C, Amsellem J, Blaineau S
Laboratoire de Physiologie des Eléments Excitables, URA CNRS 180, Université Claude Bernard Lyon I, Villeurbanne, France.
J Muscle Res Cell Motil. 1995 Oct;16(5):553-66. doi: 10.1007/BF00126439.
The ultrastructural organization of the highly interconnected filamentous network underneath the sarcolemma as well as the role played by the muscle protein dystrophin within this cytoskeleton remain yet unclear. More accurate information has been obtained by using a method which provides three-dimensional en face views of large membrane areas applied to mouse cultured myotubes and isolated adult skeletal muscle fibres. Two levels have been distinguished in the cytoskeleton underlying the sarcolemma: the submembranous level, partly integrated into the membrane, and the cortical level, invading the proximal cytoplasmic space. Few differences have been found between the membrane cytoskeletons of myotubes issued from 14-day-old cultures and those of adult fibres. The comparison was done with cells where dystrophin is missing (mdx mouse muscle): surprisingly, the lack of dystrophin does not induce obvious or dramatic ultrastructural disorganization, either in the cortical cytoskeletal network or in the submembranous one. Immunogold labelling of either the central-rod or the C-terminal domain of dystrophin is not located among the cortical network. This study provides additional data on the spatial ordering of subsarcolemmal cytoskeletal elements: dystrophin does not appear as a filamentous structure entirely located among subsarcolemmal cytoskeleton but seems partly embedded in membranous material.
肌膜下方高度互联的丝状网络的超微结构组织，以及肌肉蛋白肌营养不良蛋白在这个细胞骨架中所起的作用仍不清楚。通过一种方法获得了更准确的信息，该方法能对应用于小鼠培养肌管和分离的成年骨骼肌纤维的大膜区域提供三维正面视图。在肌膜下方的细胞骨架中区分出了两个层次：部分整合到膜中的膜下层次，以及侵入近端细胞质空间的皮质层次。在14天龄培养物产生的肌管的膜细胞骨架与成年纤维的膜细胞骨架之间几乎没有发现差异。对缺乏肌营养不良蛋白的细胞（mdx小鼠肌肉）进行了比较：令人惊讶的是，肌营养不良蛋白的缺失在皮质细胞骨架网络或膜下网络中均未引起明显或显著的超微结构紊乱。对肌营养不良蛋白的中央杆或C末端结构域的免疫金标记不在皮质网络中。这项研究提供了关于肌膜下细胞骨架元件空间排列的更多数据：肌营养不良蛋白似乎不是完全位于肌膜下细胞骨架中的丝状结构，而是部分嵌入膜性物质中。
