Agr2-/- mice lack exons 2-3 of the anterior gradient 2 (Agr2) gene, abolishing gene expression. AGR2 is present within the endoplasmic reticulum (ER) of intestinal secretory epithelial cells and is essential for the synthesis of mucin (MUC2). MUC2 is a large, cysteine-rich glycoprotein that forms the protective mucus gel lining the intestine and airway. Mice that are homozygous for this allele are viable and fertile. MUC2 synthesis is decreased and no mucus is present in the small and large intestinal mucosa of Agr2-/- mice. Incidence of rectal prolapse is increased, occurring in 5 of 8 mice during the first year of life. Mice have increased numbers of mast cells and mast cell proteases, and increased expression of ER-related genes such as Hsp90b1 (heat shock protein 90, beta (Grp94), member 1) and Sec61a1 (Sec61 alpha 1 subunit). They also have decreased expression of some genes associated with inflammation such as Klk1 (kallikrein 1) and Cyp1a1 (Cytochrome P450, family 1, subfamily a, polypeptide 1). Dextran Sodium Sulfate exposed Agr2-/- mice have bloody stool and 20% weight loss, resulting in colonic epithelial damage. Agr2-/- mice have also been used to study the role of ARG2 and MUC2 and MUC1 in asthma and pancreatic cancer progression.
A targeting vector was designed to insert a loxP site upstream of exon 2, and a frt-neo-loxP-frt-loxP cassette downstream of exon 3 of the anterior gradient 2 (Agr2) gene. The construct was electroporated into 129S4/SvJae-derived RF8 embryonic stem (ES) cells. Correctly targeted ES cells were transiently transfected with a FLP-recombinase expression plasmid to delete the neo cassette. Resulting ES cells injected into C57BL/6 blastocysts and resulting chimeric mice were bred to FVB/N-Tg(ACTB-cre)2Mrt/J transgenic mice (Stock No. 003376) to delete the neo cassette. The resulting progeny were crossed to remove the Flp-expressing transgene. The donating investigator reported that these mice were bred to C57BL/6J mice for at least 10 generations (see SNP note below). Upon arrival, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.
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, all 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 C57BL/6N genetic background.
|Allele Name||targeted mutation 1.2, David J Erle|
|Allele Type||Targeted (Null/Knockout)|
|Gene Symbol and Name||Agr2, anterior gradient 2|
|Strain of Origin||129S4/SvJae|
|Molecular Note||Exons 2 and 3 were floxed by insertion of a loxP site upstream of exon 2 and the addition of a FRT-neo-loxP-FRT-loxP cassette downstream of exon 3. The neo cassette was subsequently removed from correctly targeted ES cells by transient expression of FLPe recombinase. Mice carrying the floxed allele were crossed with transgenic mice that express cre recombinase in the germline to create a null allele. Gene inactivation was confirmed by RT-PCR analysis on intestinal extracts.|
When maintaining a live colony, homozygous mice may be bred together.
When using the B6.129S4(FVB)-Agr2tm1.2Erle/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #025630 in your Materials and Methods section.