Reversibility of muscle differentiation in the absence of commitment: analysis of a myogenic cell line temperature-sensitive for commitment

• Published in: Cell Vol. 34; no. 1; p. 281
• Main Authors: Nguyen, H T, Medford, R M, Nadal-Ginard, B
• Format: Journal Article
• Language: English
• Published: United States 01-08-1983
• Subjects: Actins - biosynthesis; Animals; Cell Cycle; Cell Differentiation; Cell Fusion; Cell Line; Cytoskeleton - ultrastructure; Gene Expression Regulation; Mice; Muscle Proteins - biosynthesis; Muscle Proteins - genetics; Muscles - cytology; Muscles - metabolism; Myosins - biosynthesis; RNA, Messenger - biosynthesis; Temperature; Transcriptional Activation; Troponin - biosynthesis; Troponin T
• ISSN: 0092-8674
• 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 In the absence of commitment, the cells are reversibly withdrawn from the cell cycle during gene induction, and expression of the muscle-specific genes is deinduced upon the switch to growth-stimulating conditions.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.