B6.129S-Capn1^tm1Ahc/J

Stock number: 034595
Product name: calpn1^-
Research areas: Cell Biology Research, Hematological Research

Description

Capn1^-/- mice have a neo cassette replacing exon 4, encoding part of an essential catalytic domain, of the calpain 1 (Capn1) gene, abolishing endogenous gene function. These mice may be useful for studying platelet activation and aggregation.

Detailed description

Capn1^-/- mice have a neo cassette replacing exon 4, encoding part of an essential catalytic domain, of the calpain 1 (Capn1) gene, abolishing endogenous gene function. Calpains are calcium-activated neutral proteases, and are non-lysosomal intracellular cysteine proteases. Calpain 1 catalyzes limited proteolysis of substrates involved in cytoskeletal remodeling and signal transduction. It may also be involved in seizure activation and potentiation (LTP) and fear memory, cerebellar development, and cerebellar ataxia. Homozygous mice are viable and fertile.

Capn1^-/- mice lack normal and alternate transcripts and also lack calpain activity in platelets. They exhibit normal bleeding but impaired platelet aggregation, clot retraction, and tyrosine dephosphorylation defects.

When crossed to the Townes model of sickle cell disease (SCD) mice (Stock No. 013071), resulting calpain-1 knockout Townes sickle (SSCKO) mice exhibit significantly impaired PAR4-TRAP-stimulated platelet aggregation as compared to Townes sickle (SS) and humanized control (AA) mice. They exhibit reductions in all aspects of sickle chronic pain phenotype including mechanical hyperalgesia, sensitivity to heat and cold, and deep tissue hyperalgesia. Calpain-1 regulates platelet hyperactivity in sickle mice, and may offer a viable pharmacological target to reduce platelet hyperactivity in SCD.

Development

A targeting vector was designed by Dr. Athar Chishti to replace exon 4 calpain 1 (Capn1) gene with a neomycin resistance (neo) cassette. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-Kitl⁺-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts and the resulting chimeric males were bred to C57BL/6J females. These Capn1^-/- mice were backcrossed 20 generations to C57BL/6J mice (Stock No. 000664). 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 oocytes.

In 2020, 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 rederived living colony at The Jackson Laboratory Repository. One of the 43 markers throughout the genome was segregating with 129 on Chromosome 19, likely passenger segment for Capn1 mutation. Also, one of the 5 markers that determine C57BL/6J from C57BL/6N was found to be segregating at the rd8 recessive mutation associated with retinal degeneration on Chromosome 1 within the Crb1 locus. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6N;C57BL/6J genetic background.

Allele

Symbol: Capn1^tm1Ahc
Name: targeted mutation 1, Athar H Chishti
MGI accession ID: MGI:2180538
Generation method: Targeted
Attributes: Null/Knockout
Synonyms: Capn^-
Marker symbol: Capn1
Marker name: calpain 1
Marker synonyms: CANP; CANP 1; CANP1; CANPL1; Capa1; Capa-1; mu-calpin; muCANP; muCL; SPG76
Chromosome: 19
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Molecular note: A PGK-neo cassette replaced the portion of exon 4 encoding amino acids 153 through 160, part of an essential catalytic domain. Expression analysis of homozygous mutant mice showed an absence of normal transcript and additionally that alternate trancripts were not produced by cryptic splicing. Western analysis revealed a lack of protein in homozygous mutants, while casein zymography did not detect calpain activity in platelets.