MacCalman C D, Bardeesy N, Holland P C, Blaschuk O W
Department of Surgery, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada.
Dev Dyn. 1992 Oct;195(2):127-32. doi: 10.1002/aja.1001950207.
N-cadherin, N-CAM, fibronectin, and beta 1-integrins have been implicated in the control of myoblast fusion to form multinucleate myotubes, a critical step in the terminal differentiation of skeletal muscle. We have analyzed the temporal pattern of expression of mRNA transcripts encoding these adhesion molecules during the terminal differentiation of C2 mouse myoblasts. The accumulation of mRNA transcripts encoding N-cadherin, N-CAM, fibronectin, alpha 5-integrin, and beta 1-integrin subunits was developmentally, but not coordinately, regulated. N-cadherin and integrin subunit expression was maximal in prefusion myoblasts and declined thereafter. In contrast, N-CAM mRNA levels were low in prefusion myoblasts, and increased coincident with the onset of terminal differentiation. Fibronectin mRNA levels were also low in myoblasts, and they did not increase until after cell fusion had occurred. The results indicate that despite their lack of coordinate regulation maximal levels of mRNA transcripts encoding adhesion molecules are present at a stage which corresponds to the peak of the active phase of myoblast fusion.
N-钙黏蛋白、神经细胞黏附分子（N-CAM）、纤连蛋白和β1整合素与成肌细胞融合形成多核肌管的过程调控有关，这是骨骼肌终末分化的关键步骤。我们分析了C2小鼠成肌细胞终末分化过程中编码这些黏附分子的mRNA转录物的表达时间模式。编码N-钙黏蛋白、N-CAM、纤连蛋白、α5整合素和β1整合素亚基的mRNA转录物的积累受到发育调控，但并非协同调控。N-钙黏蛋白和整合素亚基的表达在融合前的成肌细胞中最高，随后下降。相反，N-CAM mRNA水平在融合前的成肌细胞中较低，并在终末分化开始时升高。纤连蛋白mRNA水平在成肌细胞中也较低，直到细胞融合发生后才升高。结果表明，尽管它们缺乏协同调控，但编码黏附分子的mRNA转录物的最高水平出现在与成肌细胞融合活跃期峰值相对应的阶段。
