Protein degradation in cultured skeletal muscle from duchenne muscular dystrophy patients

Abstract

The loss of contractile protein in Duchenne muscular dystrophy could result from low rates of synthesis, abnormally high rates of protein degradation, or a combination of both. We measured overall protein degradation rates in cultured human muscle cells obtained at biopsy from patients with Duchenne dystrophy or various muscle diseases and normal subjects. Measurements were performed on confluent cultures exhibiting no growth and containing a mixed cell population of myoblasts, fibroblasts, and multinucleated myotubes. Using a new double-isotope labeling protocol, we found protein degradation rates in all three groups to be similar (KD = 0.0171-0.0176 hr-1), suggesting no detectable abnormality of overall protein degradation in cells derived from Duchenne dystrophy patients.

Properties of acetylcholine-receptor activation in human Duchenne muscular dystrophy myotubes

“…Although there is general consent that dystrophin is missing on both dmd fibres and cultured myotubes, there is no convincing evidence about the physiological effects of this absence. In fact, dmd muscle cultures have been studied for growth characteristics (Delaporte et al 1984 ;Meola 1981) andcel Johnston et al 1981;Thompson et al 1977;Yasin et al 1979); cell-surface s have been done on membranes by freeze-fracture (Osame et al 1981), distribution of AChoRs (Franklin et al 1980), the cytoskeleton (Walsh et al 1981), and membrane proteins (Hutchison et al 1987;Neville & Harrold 1985), without significant evidence of a functional role for 'dystrophin'.…”