Partial Purification from Chick Embryos of a Factor which Promotes Myoblast Proliferation and Delays Fusion:...

Chick embryo extract (EE) contained an activity which promoted myoblast proliferation and delayed fusion. Various tissue extracts prepared from 12-day embryos and adult chicken also showed the activity. We partially purified this active substance from 12-day embryos, following procedures which included extraction at pH 3.5, CM-Sephadex C-50 ion exchange and Sephadex G-75 gel filtration. Judging from the dose-response analyses, the factor was purified by some hundred-fold when EE was used as the starting material. The activity was associated with a macro-molecular substance (MW > 300K daltons) at first, but the apparent molecular weight of the active substance was estimated to be between 16 and 20K daltons at the final step of the preparation. It promoted myoblast proliferation and delayed myotube formation, and was active for both avian and rat myoblasts. Since bovine pituitary gland fibroblast growth factor (FGF) showed the same activity, the factor may be FGF-related.