INTRINSIC DIFFERENCES IN MYOD AND MYOGENIN EXPRESSION BETWEEN PRIMARYCULTURES OF SJL J AND BALB/C SKELETAL-MUSCLE/

The time course of expression of the skeletal muscle-specific regulato ry genes MyoD and myogenin was studied in primary cultures of skeletal muscle from adult SJL/J and BALB/c mice. In situ detection of express ion with MyoD and myogenin riboprobes and myogenin antibody showed tha t the onset of expression of these genes occurred earlier in cells fro m SJL/J mice. Probe-positive cells and myotubes were also more frequen t in cultures from SJL/J mice than in BALB/c. The onset of expression of MyoD and myogenin was delayed in cultured cells relative to the tim e course seen following injury in vivo. Myogenin protein was demonstra ted in replicating cells and all myogenin-positive cells expressed des min. The observed strain-specific difference infers a greater intrinsi c myogenicity of cells in SJL/J muscle in vitro and reflects the super ior capacity for new muscle formation previously reported in SJL/J mic e in vivo. (C) 1994 Academic Press, Inc.