Nguyen H T, Medford R M, Nadal-Ginard B
Cell. 1983 Aug;34(1):281-93. doi: 10.1016/0092-8674(83)90159-9.
The interrelationship between commitment (irreversible withdrawal from the cell cycle) and muscle-specific gene expression was analyzed with the myogenic cell line ts 3b-2, which is temperature sensitive for commitment and cell fusion. The rates of synthesis and levels of accumulation of muscle-specific mRNAs and proteins in the ts 3b-2 cells at permissive and nonpermissive temperatures are comparable, indicating that neither commitment nor cell fusion is required for induction of muscle-specific gene expression. In the absence of commitment, the cells are reversibly withdrawn from the cell cycle during gene induction, and expression of the muscle-specific genes is deinduced upon the switch to growth-stimulating conditions. The deinduction reflects coordinate and preferential cessation of muscle-specific mRNA synthesis, coupled with destabilization of the muscle-specific mRNAs in the cytoplasm, without effect on constitutively expressed housekeeping protein genes. The phenotype of the ts 3b-2 cells demonstrates that commitment and muscle-specific gene expression are both required, but alone are insufficient, to produce the terminally differentiated muscle phenotype.
利用对分化和细胞融合具有温度敏感性的成肌细胞系ts 3b-2，分析了分化（从细胞周期中不可逆退出）与肌肉特异性基因表达之间的相互关系。在允许温度和非允许温度下，ts 3b-2细胞中肌肉特异性mRNA和蛋白质的合成速率及积累水平相当，这表明诱导肌肉特异性基因表达既不需要分化也不需要细胞融合。在没有分化的情况下，细胞在基因诱导过程中可逆地退出细胞周期，并且在转换到生长刺激条件时，肌肉特异性基因的表达被解除诱导。这种解除诱导反映了肌肉特异性mRNA合成的协同和优先停止，同时伴随着细胞质中肌肉特异性mRNA的不稳定，而对组成性表达的管家蛋白基因没有影响。ts 3b-2细胞的表型表明，分化和肌肉特异性基因表达对于产生终末分化的肌肉表型都是必需的，但单独存在时并不充分。
