Mice homozygous for this knock-out mutation exhibit significant degeneration of CNS axons and subtle intention tremors.
Richard Quarles, NINDS, NIH
Mice homozygous for this targeted mutation are viable and fertile. The endogenous protein had previously been thought to be necessary for myelin formation. However in the homozygous mutant the degree of myelination and its compaction are normal. Finer motor coordination abilities are significantly affected in the homozygous mutant and they exhibit a subtle intention tremor. The organization of the periaxonal region is partially impaired with the periaxonal cytoplasmic collar frequently missing in optic nerve, cervical spinal cord, and ventral roots. Later in life, beginning at 6 months, oligodendrocytes degenerate. This strain may serve as a model for some aspects of multiple sclerosis. MAG also tranduces a signal to axons. Therefore, axons in the MAG-deficient mice are smaller in calliber due to the aberrant phosphorylation of neurofilaments. MAG has also been shown to be an inhibitor of nerve regeneration. MAG-deficient mice congenic on a C57BL/6 background may exhibit substantially more degeneration of CNS axons compared to deficiency on the original mixed background.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
The targeted mutation was created by Dr. John Roder (University of Toronto) by designing a targeting vector to insert a neomycin resistance cassette into exon 5 of the targeted gene. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-derived R1 embryonic stem (ES) cells. The original strain (see Stock No. 002403) on a mixed C57BL/6, 129 inbred and the CD1 outbred genetic background was sent to Dr. Richard Quarles (NINDS/NIH). There, mutant mice were backcrossed for at least 13 generations prior to arrival at The Jackson Laboratory.
|Allele Name||targeted mutation 1, John Roder|
|Allele Type||Targeted (Null/Knockout)|
|Gene Symbol and Name||Mag, myelin-associated glycoprotein|
|Strain of Origin||(129X1/SvJ x 129S1/Sv)F1-Kitl+|
|Molecular Note||A neomycin resistance cassette was inserted into exon 5 of the gene. Mutant mice showed a complete lack of mRNA and protein in the central nervous system for the targeted gene. Nerves from the peripheral nervous system also lacked protein for the targeted gene.|
|Mutations Made By|| |
Dr. John Roder, University of Toronto
When maintaining a live colony, homozygous mice are bred.
When using the MAG KO mouse strain in a publication, please cite the originating article(s) and include JAX stock #006865 in your Materials and Methods section.