Muscle plasma membrane changes in dystrophin gene exon 52 knockout mouse

Changes in muscle plasma membranes in mice lacking exon 52 of the dystrophin gene (mdx52 mouse) were studied using the freeze-fracture technique. The extensor digitorum longus (EDL) muscle plasma membrane of the mdx52 mouse at 8 weeks of age showed significantly increased caveola density (p < 0.05 by two-tailed t-test) and significantly decreased densities of intramembranous particles (IMPs), orthogonal arrays (OAs) and orthogonal array subunit particles (OASPs) (p < 0.05 by two-tailed t-test, p < 0.01 by Wilcoxon rank-sum test, p < 0.05 by two-tailed t-test, respectively) on the protoplasmic face when compared with those of control EDL muscles. These changes are more similar to those seen in DMD than those in the mdx mouse at the same age as reported previously. Thus, the gene abnormality in the different exon of the mouse dystrophin gene seems to induce somewhat different changes in the muscle plasma membrane.