These Δ18 COX-2 mice express a mutant prostaglandin endoperoxide H synthase-2 with an 18-amino acid deletion in exon 10 that prevents the protein's entry into the endoplasmic reticulum-associated protein degradation (ERAD) system.
Masayuki Wada, Stony Brook University
Julie A. Woodruff, University of Michigan Medical School
Prostaglandin endoperoxide H synthase-2 (COX-2) catalyzes the first rate-limiting step in prostaglandin biosynthesis and is the target of non-steroidal anti-inflammatory drugs. These mice carry a knock-out allele of the Ptgs2 gene containing a deletion of the 18 amino acids required for N-glycosylation of Asn 594. This region is required for entry of the COX2 protein into the endoplasmic reticulum-associated protein degradation (ERAD) system.
Homozygous mice develop a more pronounced and prolonged bacterial endotoxin-induced febrile response than wildtype controls. 12 week old homozygous male mice exhibit approximately 50% higher levels of prostaglandin E2 in urine. Western blot analysis of serum-stimulated fibroblasts isolated from homozygotes does not detect any full length gene product (protein) and mutant Δ18 COX-2 protein levels are higher than wildtype COX-2 protein levels. Δ18 COX-2 protein levels are also higher in brain tissue from homozygotes, as determined by Western blot analysis. The catalytic activity of the Δ18 COX-2 protein is similar to that of the wildtype prostaglandin endoperoxide H synthase-2 enzyme. LPS challenge does not increase Δ18 COX-2 protein in brain, kidney or spleen. Mice that are homozygous for the targeted mutation are viable and fertile.
A targeting vector containing a loxP site flanked PGK-NEO/polyA cassette was used to disrupt 54bp of genomic sequence encoding amino acids 595 through 612 (in exon 10), and insert the floxed NEO cassette upstream of exon 10. The construct was electroporated into 129 derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting male chimeric animals were crossed to C57BL/6J female mice. Heterozygotes were bred to EIIa Cre mice on a unspecified background to excise the floxed NEO cassette. The mice were then backcrossed to C57BL/6J for 10 generations.
Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony.
|Allele Name||targeted mutation 1.1, William L Smith|
|Allele Synonym(s)||delta 18 muCox2|
|Gene Symbol and Name||Ptgs2, prostaglandin-endoperoxide synthase 2|
|Strain of Origin||(129X1/SvJ x 129S1/Sv)F1-Kitl+|
|Molecular Note||Genomic sequence that codes for amino acids 595 through 612 was deleted by mutagenesis. A floxed neo cassette was inserted upstream of the modified exon 10. Cre mediated recombination removed the neo cassette. The predicted protein lacks the last 18 C-terminal amino acids.|
When maintaining a live colony, these mice can be bred as homozygotes.
When using the Δ18 COX-2 mouse strain in a publication, please cite the originating article(s) and include JAX stock #027210 in your Materials and Methods section.