Molecular and cellular biological study on muscle differentiation and plasticity.

1.肌蛋白的动态变化：通过显微注射、光漂白和免疫荧光等方法发现，在肌原纤维内肌动蛋白的掺入和肌动蛋白的交换中，星云蛋白起着重要的作用，而连接素则没有这种作用。研究还发现，肌动蛋白和α-肌动蛋白在互换性方面存在差异。这种差异似乎与肌原纤维的I-Z-I结构的形成有关。肌原纤维形成过程中肌蛋白之间的发育关系：免疫荧光显微镜显示，肌球蛋白、连接素和C-蛋白在肌球蛋白分子的组装和规则排列中起着重要作用。一种机制是在功能结构中起到一些未知的作用后，将暂时表达的胚胎异构体(非肌肉肌动蛋白和心脏C蛋白)从功能结构中移除(S)。肌动蛋白结合蛋白和肌球蛋白结合蛋白在发育过程中的研究：1)用原位杂交方法研究了肌动蛋白结合蛋白在小鼠胚胎肌肉发生过程中的表达。2)发现了一种独特的C蛋白变异体，该变异体在老年小鼠的心房中表达更为丰富。结果表明，该蛋白仅与肌球蛋白和连接蛋白相互作用，而与重组蛋白相互作用。小鼠咬肌生长期肌纤维的特点：本研究旨在探讨肌球蛋白重链(MHC)亚型在小鼠咬肌出生后发育过程中的分化。MHC-2b在咬肌中的表达与断奶时间相一致。这一事实表明，在这一时期，从哺乳到咀嚼的转变改变了MHC的异构体。

1. Dynamics of myoproteins : By using microinjection, photobleaching and immunofluorescence, it was found that nebulin plays an important role for incorporation of actin into and exchange of actin in nascent myofibrils, but connectin does not have such a role. It was also found that difference exists in exchangeability between actin and α-actinin. This difference seems to be related to the formation of I-Z-I structures of myofibrils.2. Developmental relationship between myoproteins during myofibrillogenesis : Immunofluorescence microscopy of embryonic muscle revealed that myomesin, connectin and C-protein play an important role for assembly and regular alignment of myosin molecules. A mechnism works to remove transiently expressed embryonic isoforms (nonmuscle actin and cardiac C-protein) from functional structures after they play some unknown role (s) for structure formation.3. Studies on actin-binding and myosin-binding proteins in developing muscle : 1) Expression profile of muscle-type cofilin, an actin-binding protein characteristic of muscle, was clarified during myogenesis in mouse fetus by in situ hybridization methods. 2) A unique C-protein variant has been discovered, which is expressed more abundantly in atrium of aged mice. It was revealed that this protein interacts only weekly with myosin and connectin with recombinant protein.4. Characteristcs of myofibers in masseter muscle of mice during postnatal growth period : The purpose of this study was to investigate the differentiation of myosin heavy chain (MHC) isoforms during postnatal development of mouse masseter muscle. Expression of MHC-2b in masseter occurs in accordance with the weaning period. This fact suggests that transformation from suckling to mastication effects to change MHC isoforms at this period.