1992 Volume 17 Issue 4 Pages 237-247
Quail embryonic pectoral myoblasts fuse with each other at 35.5°C and 41°C to essentially equal extents. When the myoblasts were transformed with a temperature-sensitive mutant of Rous sarcoma virus (ts-RSV), their fusion and biochemical processes of differentiation became temperature-sensitive: their fusion occurred at 41°C, the non-permissive temperature, but not at 35.5°C, the permissive temperature, suggesting that the fusion was regulated by the viral transforming gene.
Fusion of the transformed cells proceeded more rapidly and synchronously than that of the parent cells at 41°C, and was completely suppressed at the permissive temperature, unlike that of the parent cells. These transformed cells were used to examine the relationship between myogenic differentiation and the tyrosine kinase activity of the src gene product. In spite of the temperature sensitivity of transformation, results showed that expressions of the src gene at 35.5°C and 41°C were similar. However, the level of tyrosine-phosphorylated protein was decreased at 41°C. Moreover, myoblast fusion could occur at 35.5°C in the presence of herbimycin A, an inhibitor of the tyrosine kinase activity of the src gene product. These results indicate that the tyrosine kinase activity of the src gene product is closely associated with regulation of myogenic differentiation of the cells.
