Characterization of a PLP-overexpressing transgenic rat, a model for the connatal form of Pelizaeus–Merzbacher disease

Pelizaeus–Merzbacher disease (PMD) most frequently results from duplication of the Plp1 gene with a correlation between disease severity and increasing copy number of the gene. Animal models of PMD, in particular those overexpressing the Plp1 gene, have been sought in attempts to provide systems in which potential therapies can be tested. Here we describe a rat model of the severe connatal form of PMD and provide a detailed characterization of its pathology and molecular biology, prior to testing therapeutic approaches. We determined the exact copy number of Plp1, and the resulting effects on RNA and protein expression. Distinct differences in myelin and disparate distributions of myelin protein markers in comparison to wild-type controls were observed. Altered expression of Plp1 also caused an increase in the apoptotic cell death of oligodendrocytes. These results provide the platform from which to test the effectiveness of in vivo therapies.

► Overexpression of Plp1 due to gene duplication leads to oligodendrocyte apoptosis.
► Increase in Plp1 expression does not lead to an increase in functional PLP protein.
► The PLP-overexpressing rat serves as a model for the connatal form of PMD.