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A single nucleotide difference in the gene for myelin proteolipid protein defines the jimpy mutation in mouse

K A Nave1, F E Bloom, R J Milner

  • 1Division of Preclinical Neuroscience and Endocrinology, Research Institute of Scripps Clinic, La Jolla, CA 92037.

Journal of Neurochemistry
|December 1, 1987
PubMed

Insights

The jimpy mouse mutation results from a single base change in the proteolipid protein (PLP) gene. This genetic defect disrupts RNA splicing, causing a specific exon to be absent from the PLP mRNA.

Area of Science:

  • Neuroscience
  • Genetics
  • Molecular Biology

Background:

  • The jimpy mutant mouse exhibits myelin deficiency due to aberrant RNA processing.
  • A specific 74-nucleotide sequence is missing from the proteolipid protein (PLP) mRNA in jimpy mice.

Purpose of the Study:

  • To pinpoint the exact genetic mutation responsible for the observed RNA processing defect in the jimpy mouse.
  • To analyze the proteolipid protein (PLP) gene in jimpy mice to understand the molecular basis of the mutation.

Main Methods:

  • Analysis of the proteolipid protein (PLP) gene from a jimpy mouse genomic library.
  • Comparison of the PLP gene sequence with the corresponding mRNA sequence to identify discrepancies.
  • Nucleotide sequence analysis to locate point mutations and their effects on RNA splicing.

Main Results:

  • The nucleotide sequence absent in jimpy PLP mRNA is present in the jimpy PLP gene, indicating a processing rather than a deletion issue.
  • The missing segment in the mRNA corresponds to an exon homologous to human PLP gene exon 5.
  • A single point mutation (A to G) was identified at the 3' acceptor splice site of intron 4 in the jimpy PLP gene.

Conclusions:

  • The primary genetic defect in the jimpy mouse is a single base change within the PLP gene.
  • This mutation alters a highly conserved splice acceptor recognition sequence, leading to aberrant RNA splicing.
  • The aberrant splicing results in the exclusion of an exon from the mature PLP mRNA, causing myelin deficiency.

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