EXPRESSION OF THE FGF6 GENE IS RESTRICTED TO DEVELOPING SKELETAL-MUSCLE IN THE MOUSE EMBRYO

Fgf6, a member of the Fibroblast Growth Factor (FGF) family, is develo pmentally regulated and its expression is highly restricted in the adu lt. To gain further insight into the role of Fgf6, we studied its expr ession during embryogenesis using RNA in situ hybridization. Fgf6 expr ession is restricted to developing skeletal muscle. Fgf6 transcripts a re first detected in the somites at 9.5 days post-conceptus, and expre ssion continues in developing skeletal muscles up to at least 16.5 day s post-conceptus. Fgfr4 is a putative receptor for FGF6. Its pattern o f expression during myogenesis overlaps that of Fgf6, but both genes a re not expressed in exactly the same population of cells. In addition, recombinant FGF6 protein is able to repress the terminal differentiat ion of myoblasts in culture, providing additional support to the conce pt that FGF6 plays an important role in myogenesis.