Gene expression of muscle proteins and molecular mechanisms of contractile structure formation

1. 肌原纤维形成过程中肌球蛋白结合蛋白与肌球蛋白的发育关系：胚胎骨骼肌的免疫荧光显微镜显示，肌球蛋白、连接蛋白和c蛋白对肌球蛋白分子的组装和规则排列起重要作用。也有人提出，在瞬时表达的胚胎异构体（非肌肉肌动蛋白和心脏c蛋白）在结构形成中发挥一些未知的作用后，从功能结构中移除它们的机制起作用。肌动蛋白在肌纤维形成过程中的动态：将罗丹明（rh）标记的肌动蛋白微注射到培养的骨骼肌细胞中，并用抗云母蛋白和抗连接蛋白染色。研究发现，在新生肌原纤维中，星云蛋白对肌动蛋白的掺入和肌动蛋白的交换起着重要作用，而连接蛋白则没有这样的作用。在rh-actin注射液中注射抗星云蛋白和抗连接蛋白证实了这一点。肌动蛋白和α-肌动蛋白在肌原纤维和应激纤维中的动态：将荧光标记的肌动蛋白和α-肌动蛋白共同注射到培养的心肌细胞中，发现两种蛋白在肌原纤维发育过程中的交换性存在差异。这种差异似乎与肌原纤维I-Z-I结构的形成有关。两种蛋白在成纤维细胞应力纤维中的互换性较高，因此肌原纤维和应力纤维虽然在外观和组成上相似，但结构不同。

1. Developmental relationship of myosin binding proteins to myosin during myofibrillogenesis :Immunofluorescence microscopy of embryonic skeletal muscle revealed that myomesin, connectin and C-protein play an important role for assembly and regular alignment of myosin molecules. It has also been suggested that a mechanism works to remore transiently expressed embryonic isoforms (non-muscle actin and cardiac C-protein) from functional structures after they play some unknown role(s) for structure formation.2. Dynamics of actin during myofibrillogenesis :Rhodamine (rh)-labeled actin was microinjected into cultured skeletal muscle cells and stained with anti-nebulin and anti-connectin. It was found that nebulin plays an important role for incorporaton of actin into and exchange of actin in nascent myofibrils, but connectin does not have such a role. This was confirmed by injection of anti-nebulin and anti-connectin to rh-actin injection.3. Dynamics of actin and α-actinin in myofibrils and stress fibers:Co-injection of fluorescently labeled actin and α-actinin into cultured cardiomyocytes revealed difference in exchangeability between both proteins in developing myofibrils. This difference seems to be related to the formation of I-Z-I structure of myofibrils. Exchangeability of bothproteins in stress fibers of fibroblasts was high, and thus myofibrils and stress fibers are different structures although they are similar in appearance and composition.