These Pex1-G844D mice exhibit phenotypes consistent with several features of the mild form of Zellweger spectrum disorder (ZSD) including: growth retardation, shortened life expectancy, fatty livers with cholestasis and retinopathy. In addition, this Pex1 allele possesses loxP sites for the creation of conditional knock out animals.
Steven Steinberg, Johns Hopkins University
Pex1 or peroxisomal biogenesis factor 1 encodes a member of the AAA ATPase family that is often anchored to a peroxisomal membrane where it forms a heteromeric complex involved in peroxisome biogenesis. The G843D mutation in PEX1 is associated with a mild form of Zellweger spectrum disorder (ZSD), a neurodevelopmental disorder that affects brain development, liver, adrenal and kidney function as well as vision and hearing. 20-30% of ZSD patients carry at least one G843D allele. Mice homozygous for the orthologous mouse mutation Pex1-G844D exhibit growth retardation and decreased body weight. Slightly less than 50% of mice have a median age of death of 22 days; the remaining mice live to almost one year of age. In the adult mouse, cone photoreceptors are degenerated. B wave amplitudes in both rod and cone visual systems are reduced or absent (respectively). Similar to human ZSD patients, homozygous mice have a bile acid defect associated with intestinal fat malabsorption, fatty livers and cholestasis.
In addition to the G844D amino acid substitution in exon 15, this Pex1 allele possesses loxP sites for the creation of conditional knock out animals. When bred to mice that express tissue-specific Cre recombinase, resulting offspring will have exons 12-13 deleted in the cre-expressing tissues. This strain may be useful for studying Zellweger spectrum disorder.
A targeting vector was designed to insert a loxP site into intron 11, a loxP-FRT-flanked neomycin cassette into intron 13 and a G844D point mutation into exon 15. The mutation results in a G to D change at nucleotide 2531 altering the corresponding amino acid from glycine to aspartic acid at position 844. The construct was electroporated into unspecified embryonic stem (ES) cells derived from hybrid 129xC57BL/6 mice. Correctly targeted ES cells were injected into recipient blastocysts. The resulting chimeric animals were crossed to an unspecified FLPe transgenic mouse (on a C57BL/6 background) to remove the neomycin cassette. Heterozygous mice were mated and offspring crossed to C57BL/6N for one generation. Upon arrival, mice were bred to C57BL/6N for at least 1 generation to establish the colony.
A SNP (single nucleotide polymorphism) panel analysis, with 43 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the rederived living colony at The Jackson Laboratory Repository in late 2017. The data indicates that the genetic background of this strain is 97.93 C57BL/6, with one marker on chromosome 18 segregating.
|Allele Name||targeted mutation 1.1, Steven Steinberg|
|Allele Type||Targeted (Conditional ready (e.g. floxed), Humanized sequence)|
|Gene Symbol and Name||Pex1, peroxisomal biogenesis factor 1|
|Strain of Origin||129 x C57BL/6|
|Molecular Note||A targeting vector was designed to insert a loxP site into intron 11, a loxP-FRT-flanked neomycin cassette into intron 13 and a G844D point mutation into exon 15. The mutation results in a G to A change at nucleotide 2531 altering the corresponding amino acid from glycine to aspartic acid at position 844. FLP-mediated recombination removed the FRT-flanked neo cassette.|
While maintaining a live colony, these mice are bred as heterozygotes. Mice homozygous for the mutation are growth retarded; approximately 50% of mice will not survive to a year. The Donating Investigator indicates that due to their small size, homozygotes require access to gel nutrition from weaning until 12 weeks of age.
When using the Pex1-G844D mouse strain in a publication, please cite the originating article(s) and include MMRRC stock #37405 in your Materials and Methods section.