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Jimpy-4J mouse has a missense mutation in exon 2 of the Plp gene
G B Pearsall1, N L Nadon, M K Wolf
1University of Massachusetts Medical School, Department of Cell Biology, Worcester 01655, USA.
Abstract:
We previously showed that the jimpy-4J mouse mutation is located on the X chromosome, in or closely linked to the proteolipid protein (Plp) gene. The phenotype is characterized by the most severe hypomyelination of any of the naturally occurring myelin mutant mice, sharp reduction in oligodendrocyte number, and virtual absence of PLP protein. Affected animals show tremor, seizures, and die at about 24 postnatal days. We now report that sequencing of Plp genomic and cDNAs identifies a single nucleotide substitution in exon 2 that predicts an Ala38Ser substitutions in a hydrophilic region of PLP/DM20 protein close to a transmembrane domain. This mutation occurs in a very different region of the mouse Plp gene than that jimpy-msd mutations, yet all three produce qualitatively similar phenotypes.
Insights
The jimpy-4J mouse mutation causes severe hypomyelination and oligodendrocyte loss due to a novel PLP protein defect. This genetic mutation leads to tremors, seizures, and early death in affected mice.
Area of Science:
- Neuroscience
- Genetics
- Developmental Biology
Background:
- The jimpy-4J mouse mutation is associated with severe hypomyelination and oligodendrocyte loss.
- This mutation affects the proteolipid protein (Plp) gene on the X chromosome.
- Affected mice exhibit tremors, seizures, and premature death around 24 postnatal days.
Purpose of the Study:
- To identify the specific genetic alteration responsible for the jimpy-4J mouse mutation.
- To characterize the molecular consequences of this mutation on PLP/DM20 protein structure and function.
Main Methods:
- Sequencing of Plp genomic and complementary DNAs (cDNAs) from jimpy-4J mice.
- Analysis of the predicted amino acid substitution and its location within the PLP/DM20 protein.
Main Results:
- A single nucleotide substitution in exon 2 of the Plp gene was identified.
- This substitution results in an Ala38Ser amino acid change in the PLP/DM20 protein.
- The mutation is located in a hydrophilic region near a transmembrane domain, distinct from jimpy-msd mutations.
Conclusions:
- The jimpy-4J mutation arises from a novel alteration in the Plp gene.
- Despite occurring in a different gene region, this mutation produces a phenotype similar to other jimpy mutations.
- This finding enhances understanding of PLP protein structure-function relationships in myelination.