B6.Cg-Fig4^plt1/MmJ

Stock number: 017800
Research areas: Mouse/Human Gene Homologs, Neurobiology Research

Description

The pale tremor (plt) allele is a spontaneous retrotransposon insertion in the Fig4 gene and is associated with Charcot-Marie-Tooth disease type 4J (CMT4J). Homozygous mice exhibit neuronal degeneration, juvenile lethality and diluted pigmentation.

Detailed description

The pale tremor (plt) allele is a spontaneous retrotransposon insertion in the Fig4 gene. FIG4, a lipid phosphatase homolog of the yeast SAC (suppressor of actin), catalyzes removal of a phosphate from PI(3.5)P2, a membrane-bound phospholipid involved in the trafficking and fusion of intracellular vesicles. Mutations in human FIG4 are associated with Charcot-Marie-Tooth disease type 4J (CMT4J). Initially identified by tremors, an abnormal gait, which progresses to a loss of mobility, small size, juvenile lethality and diluted pigmentation, homozygous mice are characterized by spongiform degeneration of the brain and loss of neurons from peripheral ganglia. Neuron loss and accumulation of cytoplasmic vacuoles is observed in layers 4 and 5 of the cortex, deep cerebellar nuclei, and dorsal root ganglia. Homozygote survival is dependent on strain background. On the C57BL/6 background, homozygotes are neonatal lethal; on a C3H background homozygotes survive to two weeks; on a mixed C57BL/6 and C3HeB/FeJ background, homozygotes survive 4-6 weeks. These mice may be useful in studies of Charcot-Marie-Tooth disease type 4J.

Development

The pale tremor plt mutation arose spontaneously on a mixed strain background that included C57BL/6J, C3H, 129P2/Ola and SJL in the laboratory of Dr. Miriam Meisler at the University of Michigan. Mice carrying the mutation have been crossed for at least 21 generations to C57BL/6J. Pale tremor is a 5.5 kB ETn2b retrotransposon insertion in the FIG4 homolog Fig4 gene. The retrotransposon is inserted 384 bp upstream of exon 19 and results in abnormal splicing from exon 18. Low levels of transcript cannot be detected by Northern blot, but can be detected by RT-PCR. Functionally, plt is a null mutation. The strain is maintained as a cross to C57BL/6. Upon arrival, transgenic mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Fig4^plt1
Name: pale tremor
MGI accession ID: MGI:3716838
Generation method: Spontaneous
Marker symbol: Fig4
Marker name: FIG4 phosphoinositide 5-phosphatase
Chromosome: 10
Strain of origin: mixed
Molecular note: The mouse retrotransposon ETn2Beta was inserted 384 bp upstream of exon 19 in the same orientation as the gene and was flanked by a duplication of the hexanucleotide CCCCTG. Northern blot did not detect transcript from mutants using a cDNA probe containing exons 8-15.