title: Targeted exchange of an expression cassette encoding cyclooxygenase-2 at the Ptgs1 locus.
abstract: Defining the multi-faceted roles of prostaglandins has been facilitated by studying mice with manipulated expression of the two enzymes encoding cyclooxygenase (COX) via gene targeting, with either knocked down expression of COX-1 or COX-2, a knocked-in COX-2 active site mutation and exchange of COX isoforms by insertion of a cassette encoding COX-1 into the COX-2 (Ptgs2) gene to create COX-1>COX-2 mice. Here, we sought to extend these studies by creating a new induced mutant strain with manipulated COX expression. We carried out gene targeting at the Ptgs1 locus to knock-in an expression cassette encoding COX-2 under Ptgs1 regulatory elements in a manner analogous used in COX-1>COX-2 targeting. While successful gene targeting at the Ptgs1 locus was achieved, the strategy did not yield a "basal" increase of COX-2 under Ptgs1 gene regulatory control in various cells and tissues from COX-2>COX-1 mice but rather resulted in a Ptgs1 null allele. Possible explanations as to why this strategy was unsuccessful include non-functionality of the hybrid signal peptide and aberrant transcript processing. Since a similar strategy had previously worked (i.e. COX-1 cDNA knocked-in to the Ptgs2 locus; COX-1>COX-2 mice) interpretations of our findings on murine COX biology and gene targeting are discussed.
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada.
authors.forename: Xinzhi
authors.initials: X
authors.lastname: Li
authors.forename: Manhong
authors.initials: M
authors.lastname: Guo
authors.forename: Crystal M
authors.initials: CM
authors.lastname: McCracken
authors.forename: Colin D
authors.initials: CD
authors.lastname: Funk
mesh_terms: D000818:Animals; D051545:Cyclooxygenase 1 / Q000235:genetics*; D051546:Cyclooxygenase 2 / Q000235:genetics*; D005260:Female; D055879:Gene Knock-In Techniques / Q000379:methods*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D011247:Pregnancy
chemical_list: D008565:Membrane Proteins; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496512:Ptgs1 protein, mouse