B6N.129S2-Casp1^tm1Flv/J

Stock number: 016621
Product name: ICE^-
Strain synonyms: Casp1-
Research areas: Apoptosis Research, Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

This strain, relevant to studies of inflammation and cell death, carries a knockout allele of the Casp1 gene as well as an incidental Casp4 deficiency.

Detailed description

Caspase 1 (also known as interleukin-1beta converting enzyme or ICE) knockout mice lack part of exons 6 and 7 of the Casp1 gene and do not process pro-IL-1beta (IL1B) or pro-IL-18 (IL18) into their mature forms. Therefore, stimulation of CASP1-deficient monocytes by activators of multiple pattern recognition receptors that form inflammasomes with CASP1 (including Nlrp3 and Nlrc4) fail to secrete mature IL1B or IL18. In addition, secretion of IL-1alpha (IL1A) is reduced. Caspase-1 is involved in particular cell death pathways including pyroptosis, and caspase-1 deficient cells demonstrate reduced lysis upon infection with certain pathogens.

It has recently been confirmed that these mice are de facto Casp1/Casp4 (formerly called caspase 11) double knockout mice. This is resultant from the dysfunctional nature of the naturally occuring 129 Casp4 allele (see Kayagaki et al., 2011). These Casp1 knockout mice were produced in embryonic stem (ES) cells on a 129S2 background.

Homozygous Casp1 targeted mutant mice are viable, fertile, and show no gross abnormalities in appearance, body weight or organ size for at least the first 16 weeks of life. Homozygotes are born at predicted Mendelian frequencies and the absence of mRNA was confirmed by RT-PCR analysis.

Development

A 2.5 kb EcoRI-HindIII fragment containing caspase 1 exons 4-6 and a 1.3 kb EcoRI-SmaI fragment containing exons 8-10 were subcloned with the neomycin resistance gene cassette in a thymidine kinase gene-expressing plasmid to generate the targeting vector. The vector was linearized and introduced into 129S2/SvPas-derived embryonic stem (ES) cells by electroporation. 63 clones resistant to G418 and Gancyclovir were screened by PCR using and exon 10 primer and a neo cassette specific primer. One correctly targeted clone was confirmed by Southern blot analysis. Chimeric mice were generated from the targeted ES cells and chimeras bred to germline. The donating investigator reported that the progeny were backcrossed at least 10 generations to the C57BL/6N background (see SNP note below).

A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 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. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, 2 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.

Allele

Symbol: Casp1^tm1Flv
Name: targeted mutation 1, Richard Flavell
MGI accession ID: MGI:2158744
Generation method: Targeted
Attributes: Null/Knockout
Synonyms: Casp1^-; caspase-1-; ICE-
Marker symbol: Casp1
Marker name: caspase 1
Marker synonyms: Caspase-1; ICE; Il1bc; interleukin 1 beta-converting enzyme; p45
Chromosome: 9
Strain of origin: 129S2/SvPas
Molecular note: A genomic fragment containing part of exon 6 and exon 7 was replaced with a neomycin selection cassette. RT-PCR analysis on samples derived from homozygous mice demonstrated that no detectable transcript was produced from this allele.
General note: The ES cells used to generate this allele contain the linked Casp4^del truncated allele that fails to produce a functional Casp4. Phenotypes associated with this allele may be affected by the presence of the Casp^del allele. J:193522