Two novel myogenic factors identified and isolated by sequential isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis

A number of environmental factors were used experimentally to enhance myoge nesis during muscle regeneration; however, many hormones and growth factors have been shown to have the ability to increase the rate of satellite cell division, but they only work on satellite cells that are already active in many animal experiments. Recently, the crushed muscle extract (CME) of rat s was found to be able to trigger dormant adult rat satellite cells to re-e nter the cell mytogenic cycle; however, the identity of the active factors present in rat CME remains unknown. In the present study, the CME was fract ionated by the strategy of sequential isoelectric focusing and sodium dodec yl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) coupled with funct ional analysis by myoblast culture. Two satellite cell-specific myogenic fa ctors were identified and purified from CME by this strategy. One of the fa ctors has a molecular mass of around 7 kDa and another about 39 kDa. The fa ctor of 39 kDa could be retained in heparin-Sepharose column and eluted wit h phosphate-buffered saline (PBS) containing 1 M NaCl, but the 7 kDa factor did not bind to the heparin column. These two purified myogenic factors co uld synergistically trigger the proliferation and differentiation of dorman t satellite cells, whose progenies subsequently fuse in vitro, or fuse to p re-existing partially damaged muscle fibers to form full repair of the dama ged muscle fibers or to form new myotubes to replace the completely damaged muscle fibers during the cascade of muscle healing and regeneration in viv o. The identities of these two myogenic factors are under study.