Fürst D O, Osborn M, Weber K
Max Planck Institute of Biophysical Chemistry, Goettingen, Federal Republic of Germany.
J Cell Biol. 1989 Aug;109(2):517-27. doi: 10.1083/jcb.109.2.517.
Antibodies to muscle-specific proteins were used in immunofluorescence to monitor the development of skeletal muscle during mouse embryogenesis. At gestation day (g.d.) 9 a single layer of vimentin filament containing cells in the myotome domain of cervical somites begins to stain positively for myogenic proteins. The muscle-specific proteins are expressed in a specific order between g.d. 9 and 9.5. Desmin is detected first, then titin, then the muscle specific actin and myosin heavy chains, and finally nebulin. At g.d. 9.5 fibrous desmin structures are already present, while for the other myogenic proteins no structure can be detected. Some prefusion myoblasts display at g.d. 11 and 12 tiny and immature myofibrils. These reveal a periodic pattern of myosin, nebulin, and those titin epitopes known to occur at and close to the Z line. In contrast titin epitopes, which are present in mature myofibrils along the A band and at the A-I junction, are still randomly distributed. We propose, that the Z line connected structures and the A bands (myosin filaments) assemble independently, and that the known interaction of the I-Z-I brushes with the A bands occurs at a later developmental stage. After fusion of myoblasts to myotubes at g.d. 13 and 14 all titin epitopes show the myofibrillar banding pattern. The predominantly longitudinal orientation of desmin filaments seen in myoblasts and in early myotubes is transformed at g.d. 17 and 18 to distinct Z line connected striations. Vimentin, still present together with desmin in the myoblasts, is lost from the myotubes. Our results indicate that the putative elastic titin filaments act as integrators during skeletal muscle development. Some developmental aspects of eye and limb muscles are also described.
利用针对肌肉特异性蛋白的抗体进行免疫荧光检测，以监测小鼠胚胎发育过程中骨骼肌的发育情况。在妊娠第9天（g.d.），颈部体节肌节区域中含有波形蛋白丝的单层细胞开始对生肌蛋白呈阳性染色。在妊娠第9天至9.5天之间，肌肉特异性蛋白按特定顺序表达。首先检测到结蛋白，然后是肌联蛋白，接着是肌肉特异性肌动蛋白和肌球蛋白重链，最后是伴肌动蛋白。在妊娠第9.5天，已经存在纤维状的结蛋白结构，而对于其他生肌蛋白，尚未检测到结构。一些融合前的成肌细胞在妊娠第11天和12天显示出微小且不成熟的肌原纤维。这些肌原纤维呈现出肌球蛋白、伴肌动蛋白以及已知出现在Z线及其附近的那些肌联蛋白表位的周期性模式。相比之下，沿A带和A-I连接处存在于成熟肌原纤维中的肌联蛋白表位仍然随机分布。我们提出，Z线连接结构和A带（肌球蛋白丝）是独立组装的，并且I-Z-I刷与A带之间已知的相互作用发生在发育后期。在妊娠第13天和14天成肌细胞融合形成肌管后，所有肌联蛋白表位都呈现出肌原纤维的带状模式。在成肌细胞和早期肌管中可见的结蛋白丝的主要纵向取向在妊娠第17天和18天转变为明显的Z线连接条纹。波形蛋白在成肌细胞中仍与结蛋白一起存在，但在肌管中消失。我们的结果表明，假定的弹性肌联蛋白丝在骨骼肌发育过程中起整合作用。还描述了眼肌和肢体肌肉的一些发育方面。
