The induction of skeletal muscle hypertrophy by a ski transgene is promoter-dependent

The chicken c-ski gene expresses at least three alternatively spliced messages. Transgenic mice expressing proteins from cDNA corresponding to two of these messages (FB27 and FB29) under the control of a murine sarcoma virus (MSV) long terminal repeat (LTR) express the transgene in skeletal muscle and develop a muscular phenotype. Both a biologically active form of c-ski and the MSV LTR are required for the development of the muscular phenotype. The normal c-ski gene linked to two other tissue-specific promoters failed to induce muscle growth in transgenic mice, as did an inactive mutant of c-ski expressed under the control of the MSV LTR.