Molecular and cellular biology of dynamics and mechanisms of myofibrillogenesis

1.在胚胎鸡体节中肌原纤维蛋白的外观顺序：免疫荧光显微镜显示，在鸡颈部体节中，构成肌原纤维的蛋白质不是同时合成的，并且成人同种型的基因表达的开启不依赖于主要肌原纤维蛋白外观的完成。原位杂交显示心脏型肌钙蛋白C mRNA出现一个阶段2.再生肌中的肌钙蛋白和肌营养不良蛋白：在缓慢的再生纤维中，（前背阔肌）和快速（背阔肌后）肌肉，胚胎肌钙蛋白的表达早于肌营养不良蛋白，并在肌营养不良蛋白表现出相同外观的阶段后转变为其成人亚型与正常肌肉纤维中的相同。此外，尽管失神经肌肉中的再生纤维与神经支配肌肉中的再生纤维类似地启动了肌钙蛋白的表达， ...更多信息 然而，其中许多人再次恢复到胚胎状态。然而，在神经完整的再生纤维和神经切除的再生纤维之间，肌营养不良蛋白的表达没有差异。因此，肌钙蛋白和肌营养不良蛋白基因的表达在再生和神经过程中受到独立调控，前者是完全发育所必需的，而后者则是不必要的。3.肌原纤维发生过程中的蛋白动力学：用免疫金电镜观察心肌细胞注射生物素-肌动蛋白和-肌球蛋白后，发现金标记首先出现在A带，I近端肌原纤维连接水平。因此，肌动蛋白和肌球蛋白的聚合似乎分别与肌球蛋白丝和肌原纤维的A-I连接区相关。将罗丹明标记的肌肉肌动蛋白和非肌肉肌动蛋白显微注射到培养的鸡心肌细胞和成纤维细胞中，荧光恢复（FR）研究表明，应力纤维比肌原纤维具有更快的FR;在肌原纤维中，肌肉肌动蛋白的FR比非肌肉肌动蛋白的FR快，新生肌原纤维显示不同的FR ;并且应力纤维在近端和末端部分与肌肉和非肌肉肌动蛋白具有相似的FR。少

1.Order of appearance of myofibrillar proteins in embryonic chicken somites : Immunofluorescence microscopy revealed that in chicken cervical somites the proteins constituting myofibrils are not synthesized simultaneously and the turning-on of the gene expression of the adult isoforms was not dependent on the completion of the appearance of the major myofibrillar proteins. In situ hybridization showed that cardiac type troponin C mRNA appeared one stage (about 3 hours) earlier than its protein.2.Troponin and dystrophin in regenerating muscle : In regenerating fibers of the slow (anterior latissimus dorsi) and fast (posterior latissimus dorsi) muscles of adult chickens, embryonic troponin was expressed earlier than dystrophin and changed to its adult isoform later than the stage when dystrophin exhibited the same appearance as that in normal muscle fibers. Further, although regenerating fibers in denervated muscle switched on the expression of troponin similarly to those in innervated m … More uscle, many of them again reverted to an embryonic state. However, no difference was found in the dystrophin expression between regenerating fibers with nerves intact and those with nerves resected. Thus, it appears that the expression of troponin and dystrophin genes in regulated independently during regeneration and nerves are required for the full development of the former protein while unnecessary for the latter.3.Protein dynamics during myofibrillogenesis : Immunogold electron microscopy of cardiomyocytes microinjected with biotin-actin and -myosin showed that gold labeling was first found at the A band and the A-I junctional level of proximal myofibrils, respectively. Thus, polymerization of actin and myosin seems to occur in association with myosin filaments and with A-I junctional regions of myofibrils, respectively. Fluorescence recovery (FR) study of rhodamine-labeled muscle and nonmuscle actins microinjected into cultured chicken cardiomyocytes and fibroblasts showed that stress fibers had faster FR than myofibrils ; in myofibrils FR of muscle actin was faster than that of nonmuscle actin, and nascent myofibrils displayd different FR ; and stress fibers had similar FR at both proximal and terminal portions with both muscle and nonmuscle actins. Less