Dynamic restoration of dystrophin to dystrophin-deficient myotubes

Abstract

Dystrophin domains are observed in myoblast transplantation experiments and in muscle fibers after somatic reversion in human Duchenne and mdx mouse muscular dystrophy. However, the formation and evolution of dystrophin‐positive domains are not well established. Using a muscle satellite cell coculture system, we examined the dynamic restoration of dystrophin expression in dystrophin‐deficient myotubes. The dystrophin‐positive domains around source nuclei were clearly identified in hybrid myotubes. The occurrence of dystrophin domains was higher in myotubes differentiated from cocultures with a low concentration of normal wild‐type satellite cells in relation to dystrophin‐deficient satellite cells. At higher seeding ratios, the domain feature of dystrophin expression was more transitory and decreased as myotubes differentiated over time in culture. The average domain size initially increased with the addition of new nuclei by fusion early after differentiation of cocultures. However, separating dystrophin‐positive domains according to their number of dystrophin‐expressing contributory nuclei showed that diffusion of dystrophin contributed to domain elongation, even in early myotubes and later without fusion of additional nuclei. Diffusion occurred for all domains of one to six wild‐type nuclei, and the diffusion rate was higher in domains with larger numbers of nuclei. This dynamic domain feature of dystrophin expression was also related to restoring the organization of dystrophin‐associated proteins and acetylcholine receptors to hybrid myotubes. Factors regulating domain formation and diffusion therefore are important considerations in the design of strategies for both myoblast transplantation and gene therapy of Duchenne muscular dystrophy. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 77–88, 2001

The satellite cell as a companion in skeletal muscle plasticity:currency, conveyance, clue, connector and colander

“…We observed that the domain of each myoblast nucleus enlarges during growth in culture, and that dystrophin diffuses along myotubes prior to the organization of a mature fibre cytoskeleton that is localized immediately inside the sarcolemma (Kong and Anderson, 2001).…”

Muscle reconstitution by muscle satellite cell descendants with stem cell-like properties

“…Incorporated donor nuclei may supply only a limited amount of dystrophin that covers the limited area designated the nuclear domain of a host myofiber (Kong and Anderson, 2001). Therefore, incorporation of a large number of donor nuclei into host myofibers is required to produce amounts of dystrophin adequate to be distributed over the whole area of the plasma membrane of a host fiber.…”

Adult stem cells derived from skeletal muscle — biology and potential

“…Qu-Petersen et al demonstrated restoration of dystrophin production in mdx mice (a mouse model of DMD which has a point mutation within its dystrophin gene) after transplantation of allogenic MDSCs [37]. Similar results were obtained by injecting satellite cells, mesoangioblasts and pericytes in high densities in to dystrophic muscle [52,66,67]. More recently, attention is focused on the use of genetically modified MDSCs, e.g.…”