ACTIVIN-A INHIBITS DIFFERENTIATION OF CHICK MYOGENIC CELLS IN-VITRO

We investigated the effect of activin A on the in vitro differentiatio n of primary myogenic cells isolated from chick embryonic breast muscl e. As judged by the morphology of the cells and accumulation of creati ne kinase, activin A inhibited myogenesis in a dose-dependent manner. The inhibitory activity was reversibly suppressed by folistatin. Activ in A also inhibited the expression of MyoD1. Our data also suggest tha t the inhibitory activity of activin A is exerted neither on prolifera tion of myoblasts or the growth of myotubes, but rather an early phase of differentiation following the withdrawal from cell cycle. A compar ison of actions of activin A and TGF-beta suggests that points of acti on is similar.