Cardiac actin is the major actin gene product in skeletal muscle cell differentiation in vitro.
We examined the expression of alpha-skeletal, alpha-cardiac, and beta- and gamma-cytoskeletal actin genes in a mouse skeletal muscle cell line (C2C12) during differentiation in vitro. Using isotype-specific cDNA probes, we showed that the alpha-skeletal actin mRNA pool reached only 15% of the level reached in adult skeletal muscle and required several days to attain this peak, which was then stably maintained. However, these cells accumulated a pool of alpha-cardiac actin six times higher than the alpha-skeletal actin mRNA peak within 24 h of the initiation of differentiation. After cells had been cultured for an additional 3 days, this pool declined to 10% of its peak level. In contrast, over 95% of the actin mRNA in adult skeletal muscle coded for alpha-actin. This suggests that C2C12 cells express a pattern of sarcomeric actin genes typical of either muscle development or regeneration and distinct from that seen in mature, adult tissue. Concurrently in the course of differentiation the beta- and gamma-cytoskeletal actin mRNA pools decreased to less than 10% of their levels in proliferating cells. The decreases in beta- and gamma-cytoskeletal actin mRNAs are apparently not coordinately regulated.
D000199:Actins / Q000235:genetics*; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002999:Clone Cells; D003001:Cloning, Molecular; D005796:Genes; D006801:Humans; D051379:Mice; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification
D000199:Actins; D012333:RNA, Messenger