B6.129S6(Cg)-Asah1^tm1Medin/J

Stock number: 039415
Product name: P361R-FD
Strain synonyms: Black6 Farber
Research areas: Metabolism Research

Description

P361R-FD knock-in mice harbor a C to G point mutation in the N-acylsphingosine amidohydrolase 1 (Asah1) gene, resulting in a single amino acid substitution of proline to arginine at residue 361 (p.P361R). These mice may be useful for studying lysosomal storage disorders such as Farber disease (FD) or spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME).

Detailed description

N-acylsphingosine amidohydrolase 1 (Asah1) codes for the enzyme acid ceramidase. Mutations in this gene result in lipid accumulation implicated in lysosomal storage disorders such as Farber disease (FD) and spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME). The P361R mutation in this model is found in Farber disease patients (P362R). These P361R-FD mice harbor a C to G point mutation in the Asah1 gene, resulting in a single amino acid substitution of proline to arginine at residue 361 (p.P361R). This model also contains an intact floxed neomycin cassette in intron 12.

Homozygous P361R-FD mice, with floxed neomycin cassette intact, show a significant reduction of acid ceramidase activity and accumulation of ceramides in multiple tissues (liver, heart, spleen, thymus and brain). P361R-FD homozygous mice on a C57BL/6J-congenic background also display splenomegaly, significant weight loss and a median survival of ~50 days. Heterozygous P361R-FD mice are viable and fertile with no overt phenotype.

The donating laboratory indicates that removal of the floxed neomycin cassette, by crossing to a Sox2 Cre mouse line (Stock No. 008454), results in progeny that demonstrate a less severe phenotype compared to the P361R-FD mice. The P361R knock-in mice, with neomycin cassette removed are referred to as P361R-SMA. The P361R-SMA mice on a C57BL/6J-congenic background, still demonstrate reduced enzymatic activity but show an increase in survival (~145 days of age) and do not demonstrate the same visceral pathologies found in the neo intact Farber disease model (P361-FD). P361R-SMA mice display significant spinal cord demyelination as well as a progressive ataxia.

This mouse model may be useful for studying lysosomal storage diseases, such as FD and SMA-PME.

Development

The P361R-FD knock-in (KI) allele was generated by inserting a proline to arginine amino acid substitution at position 361 (P361R) in the N-acylsphingosine amidohydrolase 1 (Asah1) gene. The targeting vector also contains a loxP-flanked neomycin cassette in intron 12. The construct was electroporated into 129S6/SvEvTac-derived W4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and the resulting chimeric mice were bred to CD1 mice for germline transmission. Heterozygous P361R-FD mice, with neo cassette intact, were then bred to C57BL/6J mice for at least 6 generations using a marker-assisted series of backcrosses by the donating laboratory. Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J (Stock No. 000664) oocytes.

Allele

Symbol: Asah1^tm1Medin
Name: targeted mutation 1, Jeffrey Medin
MGI accession ID: MGI:5792731
Generation method: Targeted
Attributes: Not Specified
Synonyms: Asah1^P361R
Marker symbol: Asah1
Marker name: N-acylsphingosine amidohydrolase 1
Marker synonyms: 2310081N20Rik; AC; ACDase; acid ceramidase; ASAH; PHP; PHP32; SMAPME
Chromosome: 8
Strain of origin: 129S6/SvEvTac
Molecular note: A floxed neomycin resistance cassette was inserted upstream of the modified exon 13 in which a C-to-G point mutation results in the replacement of proline with arginine at position 361 (p.P361R). This mutation was identified in patients with Farber disease (FD).