MDX/SCID mice exhibit necrosis, centrally located nuclei and and the muscle degeneration characteristic of DMD and may be used a dystrophic model for the transplantation of human donor cells to evaluate skeletal muscle regeneration.
Johnny Huard, University of Pittsburgh
The X-linked dystrophin gene (Dmd) is highly expressed in muscle cells and encodes a cytoskeletal protein which localizes to the inner face of the sarcolemma. Dystrophin molecules bind to cytoskeletal F-actin and transmembrane beta-dystroglycan as part of a complex, multimolecular unit that mediates signaling between the intracellular cytoskeleton and the extracellular matrix. The structure and localization also suggest that dystrophin is important for stabilizing the plasma membrane, particularly during contraction. Like human patients who suffer from one of the most common neuromuscular diseases, Duchenne muscular dystrophy (DMD), the Dmdmdx mutants do not express dystrophin and therefore have been routinely used as an animal model of the disease even though the resultant myopathology is much less severe compared to the human disease course. When combined with the Prkdcscid allele, there is some amelioration of the mdx phenotype including a reduction in the rate of muscle fibrosis, higher endurance and decreased expression of active TGFB1. However, MDX/SCID mice continue to exhibit necrosis, centrally located nuclei and and the muscle degeneration characteristic of DMD. The MDX/SCID mouse may be used a dystrophic model for the transplantation of human donor cells to evaluate skeletal muscle regeneration.
The spontaneous mutation Dmdmdx arose just prior to 1977 at the Agricultural Research Council's Poultry Research Centre, U.K., in C57BL/10ScSn mice obtained from M. Festing (MRC Laboratory Animals Centre, Carshalton, Surrey, U.K.). Mice carrying the mdx allele were imported to The Jackson Laboratory in 1984 by Dr. Thomas Roderick, who received them from Dr. Karen Moore (Department of Genetics, University of California, Berkley). In 2000, under the direction of James Cummins at the University of Pittsburgh and Children's Hospital of Pittsburgh, the Prkdcscid allele from B6.CB17-Prkdcscid/SzJ was introgressed into C57BL/10ScSn-Dmdmdx/J for at least 10 generations.
This strain is maintained as homozygous for Prkdcscid allele and by sibling mating homozygous Dmdmdx females with hemizygous Dmdmdx males; mice can breed up to six months of age.
|Allele Name||X linked muscular dystrophy|
|Allele Synonym(s)||mdx; pke; pyruvate kinase expression|
|Gene Symbol and Name||Dmd, dystrophin, muscular dystrophy|
|Strain of Origin||C57BL/10ScSn|
|Molecular Note||This mutation arose in 1981 in a C57BL/10ScSn colony at University of Leicester. A C-to-T substitution in the CAA codon in exon 23 (ENSMUST00000114000 chrX:g.83803333C>T; c.2983C>T; p.Q995*) results in a termination codon (TAA) in place of a glutamine codon. This allele is predicted to produce a truncated protein.|
|Allele Name||severe combined immunodeficiency|
|Gene Symbol and Name||Prkdc, protein kinase, DNA activated, catalytic polypeptide|
|Site of Expression||T and B lymphocytes.|
|Strain of Origin||C.BKa-Ighb/Icr|
|Molecular Note||A T-to-A transversion point mutation at a position corresponding to codon 4046 (codon 4095 in transcript ENSMUST00000023352.8) created a premature stop codon (p.Y4046*).|
While maintaining a live colony, these mice are bred as homozygotes for both alleles.
When using the MDX/SCID mouse strain in a publication, please cite the originating article(s) and include JAX stock #018018 in your Materials and Methods section.