This ENU-induced mutant mouse strain expresses an altered Rnu2-8 U2 snRNA gene. Homozygous mice exhibit a progressive ataxia and neurodegeneration. This mutant line may have applications in studies related to neuron degeneration and the regulation of U2 snRNA gene processing.
Susan L. Ackerman, University of California, San Diego
U2 small nuclear RNA (Rnu2-8) is one of five small nuclear RNAs, which comprise the spliceosome machinery and are responsible for the splicing of pre-mRNAs. The ethylmethanesulfonate (EMS)-induced nmf291 allele is a 5 base pair deletion, which results in alternative splicing defects, including the retention of small introns. Mice homozygous for the mutation exhibit mild tremors beginning at 4 weeks of age and progress to truncal ataxia by 12 weeks of age. The ataxia is characterized by splayed hind feet, a lumbering gait and a tendency to intermittently jump into the air. Granule cell degeneration begins at 4 weeks of age and occurs mainly in the cerebellum, but later progresses to the dentate gyrus region of the hippocampus.
Mice heterozygous for the mutation develop late onset (2 years) tremors and some granule cell degeneration. Standard pathology work-up on three mutants (84 -138 days of age) revealed severe loss of granule cells.
Both female and male homozygotes breed, but the reproductive window is shortened by the progressive physical impairments, females may have difficulties taking care of litters. This strain may be useful for studying pre-mRNA splicing and neurodegeneration.
This mutation was induced in (C57BL/6J x 129S4/SvJae)F1 derived v6.4 ES cells via exposure to ethylmethanesulfonate (EMS)during a forward genetic screen for recessive neurological phenotypes at the Neuroscience Mutagenesis Facility at The Jackson Laboratory. The mutation results in a 5 base pair deletion between nucleotides 30 and 34 in a highly conserved region of the Rnu2-8 transcription unit. The deletion removes the first 2 nucleotides of the U2 consensus branch site recognition sequence (BRSR) and a 3 nucleotide linker between BRSR the U2/U6 helix. This strain has been backcrossed to C57BL/6J for two generations and was cryopreserved in 2004.
|Allele Name||neuroscience mutagenesis facility, 291|
|Allele Type||Chemically induced (other)|
|Gene Symbol and Name||Rnu2-8, U2 small nuclear RNA 8|
|Strain of Origin||(C57BL/6J x 129S4/SvJae)F1|
|Molecular Note||This phenotypic allele was identified in an ethylmethanesulfonate (EMS) mutagenesis screen for neurological phenotypes. The molecular defect is a 5 base pair deletion between nucleotides 30 and 34 in a highly conserved region located in the U2 consensus branch site sequence (BSRS) and the linker region between the BSRS and the U2/U6 helix.|
While maintaining a live colony, these mice are bred as homozygotes, however,the reproductive window is shortened by the progressive physical impairments.
When using the B6;129-Rnu2-8nmf291/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #005048 in your Materials and Methods section.