B6.129S7-Vapb^tm1.1Tsud/J

Stock number: 028360
Product name: Vapb^P56S knock-in
Research areas: Neurobiology Research, Research Tools

Description

The Vapb^P56S knock-in allele has the endogenous Vapb exon 2 replaced by a mutant encoding the P56S amino acid change associated with human amyotrophic lateral sclerosis 8 (ALS8). Homozygotes exhibit several characteristics of the human disease, including cellular pathological features (accumulation of ubiquitinated proteins, ER stress and autophagic response) that are followed by late-onset motor behavior defects. Heterozygotes are less severe; showing mild age-dependent defects in motor behaviors.

Detailed description

The Vapb^P56S knock-in allele has the P56S mutation associated with human amyotrophic lateral sclerosis 8 (ALS8) inserted into exon 2 of the vesicle-associated membrane protein-associated protein B and C locus (Vapb). Homozygous mice (Vapb^P56S/P56S) exhibit a slowly progressive motor neuron disease with cellular pathological features prior to late-onset motor behavior defects; characteristic of the human ALS8 / spinal muscular atrophy (SMA) associated with VAPB^P56S. Specifically, the homozygous cellular pathology is accumulation of VAPB^P56S and ubiquitinated proteins in cytoplasmic inclusions (selectively in motor neurons), as well as induction of ER stress and autophagic response in motor neurons. Heterozygous mice (Vapb^P56S/+) are less severe; showing mild age-dependent defects in motor behaviors as characteristic features of the disease. Both heterozygous and homozygous mice are viable and fertile, with normal Mendelian distribution. The Vapb^P56S knock-in allele is transcribed at comparable levels to those of the endogenous Vapb gene, but the P56S mutation renders the VAPB^P56S protein detergent-insoluble.

The Vapb^P56S knock-in mice were first published/characterized on the 129SvEv genetic background in 2015, and this phenotype is described above. It should be noted that the phenotype of the C57BL/6-congenic Vapb^P56S knock-in mice could vary from that originally described on a 129SvEv genetic background. However, the donating investigator reports that Vapb^P56S knock-in mice on the C57BL/6 background and Vapb^P56S knock-in mice on the 129SvEv background show the same cellular biological defects; including VAPB positive inclusion and accumulation of ubiquitinated proteins.

Development

The Vapb^P56S knock-in mutation was designed by Dr. Hiroshi Tsuda (McGill University) to have exon 2 of the vesicle-associated membrane protein-associated protein B and C gene (Vapb; ALS8) on chromosome 2 replaced with the P56S mutant Vapb (Vapb^P56S) exon 2 and a loxP-flanked PGK-neo cassette. The targeting vector was electroporated into 129S7/SvEvBrd-Hprt^b-m2-derived AB2.2 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. Chimeric males were bred to 129S7/SvEv females for germline transmission. The donating investigator reports that mice were bred with CMV-Cre mice (Hprt^{tm1(CMV-cre)Brd}; 129S7/SvEv genetic background) for germline deletion of the PGK-neo cassette. The resulting Vapb^P56S colony was maintained by breeding heterozygous males with C57BL/6J females for at least eight generations, and then by several years of homozygous matings. In 2015, homozygous males were sent to The Jackson Laboratory Repository. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

Of note, the donating investigator reports that prior to sending to The Jackson Laboratory, the Y chromosome may not have been fixed to the C57BL/6J background during backcrossing.

Allele

Symbol: Vapb^tm1.1Tsud
Name: targeted mutation 1.1, Hiroshi Tsuda
MGI accession ID: MGI:5697413
Generation method: Targeted
Attributes: Humanized sequence
Marker symbol: Vapb
Marker name: vesicle-associated membrane protein, associated protein B and C
Chromosome: 2
Strain of origin: 129S7/SvEvBrd-Hprt1^b-m2
Molecular note: The targeting vector is designed to replace exon 2 of the gene with the an altered exon 2 carrying a P56S (proline to serine) missense mutation and a loxP-flanked PGK-neo cassette. Cre-mediated recombination removed the floxed neo cassette.