B6.Cg-Ces1c^tm1.1Loc/J

Stock number: 014096
Research areas: Research Tools

Description

These mutant mice lack exon 5 of the Ces1c gene, abolishing gene function. These mice may be useful as a model in which to measure and protect against nerve agents and for testing drugs that are hydrolyzed by ES1.

Detailed description

These Es1^-/- knockout mice lack exon 5 of the carboxylesterase 1C (Ces1c or Es1) gene, abolishing gene function. Mice that are homozygous for this allele are viable, fertile, and normal in size. Carboxylesterases are expressed in the liver and are found in many tissues including the intestine, lung, and in the plasma of mice, but not in the plasma of humans. To mimic the lack of ES1 in human plasma and the resulting increase in susceptibility to nerve agents and to drugs that are hydrolyzed by ES1, these mice have had plasma ES1 activity eliminated. ES1 acts as an organophosphorus (OP) bioscavenger which reduces the level of OP reaching biologically relevant targets and protects against lethal toxicity from nerve agents. Es1^-/- mice have normal acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and paraoxonase plasma activity, with normal levels of carboxylesterase activity in other tissues, including the brain, lungs, liver, intestines, and heart. These mutant mice react in a similar manner as control mice to some low toxicity OP agents, such as cyclosarin thiocholine analog and tabun, and are protected against some nerve agents, such as chlorpyrifos and chlorpyrifos oxon. They also display increased sensitivity to soman coumarin as noted by decreased body temperature and increased morbidity. These mice may be useful as a model in which to measure and protect against nerve agents and for testing drugs that are hydrolyzed by ES1.

Development

A targeting vector was designed to insert a loxP site upstream of exon 5, and a neomycin resistance (neo) cassette followed by a single loxP site downstream of exon 5 of the carboxylesterase 1C (Ces1c or Es1) gene. The construct was electroporated into B6.Cg-Thy1^a-derived Bruce 4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and resulting chimeric mice were bred to C57BL/6 mice. These mice were then bred to Ozcre-deleter mice on a C57BL/6 background to remove exon 5 and the neo cassette. Subsequently these mice were bred to C57BL/6J for at least 2 generations by the donating laboratory (see SNP note below) to generate a colony of Es1^-/- mice. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.

In 2021, 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 5 markers, on Chromosome 19, that determine C57BL/6J from C57BL/6N was found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6N;C57BL/6J genetic background.

Allele

Symbol: Ces1c^tm1.1Loc
Name: targeted mutation 1.1, Oksana Lockridge
MGI accession ID: MGI:4938302
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Ces1c
Marker name: carboxylesterase 1C
Chromosome: 8
Strain of origin: B6.Cg-Thy1^a
Molecular note: A targeting vector was designed to insert a loxP site upstream of exon 5, and a neomycin resistance (neo) cassette followed by a single loxP site downstream of exon 5. Cre-mediated recombination removed exon 5 and the neo cassette. This deletion is predicted to abolish protein function. The absence of carboxylesterase activity in the plasma was confirmed by enzymatic assay.