STOCK C9orf72^tm1Lgu/J

Stock number: 032107
Product name: C9orf72 floxed exons 4-5 , C9orf72^flox+neo , Cre-inducible C9orf72 knock-out
Research areas: Neurobiology Research, Research Tools

Description

C9orf72^flox+neo (C9orf72 floxed exons 4-5) mice allow Cre recombinase-inducible C9orf72 knock-out. These mice may be useful for studying amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) and frontotemporal dementia (FTD).

Detailed description

Mutations in the C9orf72 member of C9orf72-SMCR8 complex gene (C9orf72) are associated with human amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD).

The C9orf72^flox+neo allele has loxP sites flanking exons 4-5 of the C9orf72 locus. A frt-flanked neo cassette is also present between exon 5 and the proximal loxP site. Prior to Cre recombinase exposure, mice heterozygous or homozygous for the C9orf72^flox+neo allele are viable and fertile with normal breeding, and no reported gross physical or behavioral abnormalities. The donating investigator reports the frt-flanked neo cassette does not appear to adversely affect endogenous gene expression or expression of surrounding genes based on transcriptional analysis.

When C9orf72^flox+neo are bred to mice that express Cre recombinase, the resulting offspring will have the floxed region deleted in cre-expressing tissues - creating the predicted knock-out allele C9orf72^Δex4-5 (see note on western blot below). The phenotype of C9orf72^Δex4-5 homozygous mice has not been fully characterized to date (November 2018).

Of note, the donating investigator reports several approaches for western blot analyses have been performed to date (November 2018), but the results are confounded due to difficulties with commercially-available C9orf72 antibodies.

Development

The C9orf72 floxed exons 4-5 allele (C9orf72^flox+neo) was created in the laboratory of Dr. Leonard P. Guarente (Massachusetts Institute of Technology). First, a targeting vector was designed to insert a loxP site upstream of exon 4, and a frt-neo-frt::loxP cassette downstream of exon 5 of the C9orf72 member of C9orf72-SMCR8 complex locus (C9orf72) on chromosome 4. The donating investigator reports the targeting vector was electroporated into (C57BL/6 x 129S4/SvJae)F1-derived v6.5 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric animals were bred to C57BL/6 mice for germline transmission of the C9orf72^flox+neo allele. The colony was maintained by breeding C9orf72^flox+neo mice together, to C57BL/6 inbred mice and/or to Nestin-Cre animals on a C57BL/6J genetic background (see Stock No. 003771). In 2018, C9orf72^flox+neo males (black coat color) were sent to The Jackson Laboratory Repository. Upon arrival, they were bred once to C57BL/6J inbred mice (Stock No. 000664) and the Nestin-Cre allele was removed. SNP results (in detail below) indicated those mice were mixed C57BL/6;129 genetic background (~80-90% C57BL/6). At least two additional generations of backcrossing to C57BL/6J was then performed to establish our C9orf72^flox+neo colony.

In 2018, a 48 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 first generation rederived living colony at The Jackson Laboratory Repository. The results suggest the mice are on a mixed C57BL/6;129 genetic background (~80-90% C57BL/6), and the C57BL/6 contributions may be from C57BL/6J or C57BL/6N.

Allele

Symbol: C9orf72^tm1Lgu
Name: targeted mutation 1, Leonard Guarente
MGI accession ID: MGI:6241351
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed)
Synonyms: C9orf72^flox+neo
Marker symbol: C9orf72
Marker name: C9orf72, member of C9orf72-SMCR8 complex
Marker synonyms: 3110043O21Rik; ALSFTD; C5h9orf72; Dennd9; DENNL72; FTDALS; FTDALS1; RGD1359108
Chromosome: 4
Strain of origin: (C57BL/6 x 129S4/SvJae)F1
Molecular note: The targeting vector is designed to insert a loxP site upstream of exon 4, and a frt-neo-frt::loxP cassette downstream of exon 5.