Cn. Tennyson et al., EXPRESSION OF THE DYSTROPHIN ISOFORM DP71 IN DIFFERENTIATING HUMAN FETAL MYOGENIC CULTURES, Human molecular genetics, 5(10), 1996, pp. 1559-1566
The dystrophin gene defective in Duchenne muscular dystrophy (DMD) is
extreme in size and complexity with several promoters which direct exp
ression of different isoforms in different tissues, In contrast with a
dult skeletal muscle which expresses 427 kDa dystrophin, fetal muscle
tissue expresses the 71 kDa ubiquitous isoform Dp71 as well as 427 kDa
muscle dystrophin. To examine Dp71 expression in fetal muscle further
, we have monitored its expression pattern in differentiating myogenic
cultures of human fetal muscle origin, The presence of transcripts in
itiated from the Dp71 promoter was demonstrated by quantitative RT-PCR
, The level of transcript expressed from the Dp71 promoter did not cha
nge significantly during myogenic differentiation, consistent with the
housekeeping nature of the promoter. Measurements to determine the st
ability of the Dp71 mRNA indicated that it has a half-life of similar
to 20 h and, therefore, is somewhat more stable than the larger 14 kb
muscle dystrophin mRNA (t(1/2) = 16 h), In contrast with the constant
level of Dp71 transcript during myogenic differentiation, the level of
Dp71 protein increased significantly, perhaps due to changes in trans
lation efficiency or protein stability, These results demonstrate expr
ession and posttranscriptional upregulation of Dp71 in human fetal myo
genic cultures.