RHABDOMYOSARCOMAS DO NOT CONTAIN MUTATIONS IN THE DNA-BINDING DOMAINSOF MYOGENIC TRANSCRIPTION FACTORS

Skeletal myogenesis is regulated by a group of transcription factors ( MyoD, myogenin, myf5, and myf6) that are ''basic helix-loop-helix'' pr oteins that bind to the promoters of muscle-specific genes and promote their expression. We have previously shown that after a mutation of L eu(122) to Arg the DNA binding basic domain of MyoD confers c-myc-like functional characteristics to the protein. in this study we used sing les-strand conformation polymorphism analysis to determine whether suc h mutations occur naturally in rhabdomyosarcomas. We have found that t he basic domains of all the myogenic factors remain unaltered in rhabd omyosarcomas. Selection against such mutations may be the result of fu nctional redundancy of these myogenic transcription factors.