EXPRESSION OF THE C-SKI PROTOONCOGENE DURING CELL-CYCLE ARREST AND MYOGENIC DIFFERENTIATION

Although the ski oncogene plays a role in cell proliferation, morpholo gical transformation, and myogenic differentiation, the myogenic activ ities of the proto-oncogene c-ski have yet to be elucidated, c-ski is expressed within myoblasts during embryogenesis, Transcripts from the proto-oncogene can be detected in somites early in myogenic commitment , as well as in terminally differentiated skeletal muscle, However, c- ski mRNAs expressed in cells of the myogenic lineage are indistinguish able from c-ski transcripts in other cell types, raising the possibili ty that muscle-specific c-ski transcripts are expressed transiently, A vian cell lines QM7 and QM5 were used as a model to analyze changes in expression and alternative exon usage of c-ski during synchronous mus cle differentiation. Upon serum deprivation, QM7 cells undergo myogeni c differentiation, In contrast, QM5 cells cease proliferation but do n ot differentiate. Results show that levels of expression and alternati ve splicing of c-ski transcripts remain unchanged during cell cycle ar rest or myogenic differentiation.