Transdifferentiation of isolated striated muscle of jellyfish in vitro: the initiation process.

Fragments of striated muscle tissue of Anthomedusae can be isolated and cultured. Without further treatment the isolated muscle fragments maintain the differentiated state. When treated with enzymes degrading the adhering extracellular matrix, drugs activating protein kinase C or substances destroying the actin cytoskeleton, dedifferentiation and DNA replication are initiated and transdifferentiation to several new cell types occurs. Initiation of DNA replication seems to be correlated with a disturbance of cell-ECM interactions. If muscle fragments are combined with isolated ECMs, cell migration onto the grafted ECMs occurs and DNA-replication and transdifferentiation are initiated in those cells which adhere to both, the native and the grafted ECM. If, however, the cells can stretch into a monolayer and adhere entirely to either the native or the grafted ECM, DNA-replication is inhibited. Carbohydrate moieties seem to be involved in mediating these cell-substrate interactions.