Expression of mouse membrane-associated prostaglandin E₂ synthase-2 (mPGES-2) along the urogenital tract

Prostaglandin E₂ (PGE₂) is the most common prostanoid and has a variety of bioactivities including a crucial role in urogenital function. Multiple enzymes are involved in its biosynthesis. Among 3 PGE₂ terminal synthetic enzymes, membrane-associated PGE₂ synthase-2 (mPGES-2) is the most recently identified, and its role remains uncharacterized. In previous studies, membrane-associated PGE₂ synthase-1 (mPGES-1) and cytosolic PGE₂ synthase (cPGES) were reported to be expressed along the urogenital tracts. Here we report the genomic structure and tissue distribution of mPGES-2 in the urogenital system. Analysis of several bioinformatic databases demonstrated that mouse mPGES-2 spans 7 kb and consists of 7 exons. The mPGES-2 promoter contains multiple Sp1 sites and a GC box without a TATA box motif. Real-time quantitative PCR revealed that constitutive mPGES-2 mRNA was most abundant in the heart, brain, kidney and small intestine. In the urogenital system, mPGES-2 was highly expressed in the renal cortex, followed by the renal medulla and ovary, with lower levels in the ureter, bladder and uterus. Immunohistochemistry studies indicated that mPGES-2 was ubiquitously expressed along the nephron, with much lower levels in the glomeruli. In the ureter and bladder, mPGES-2 was mainly localized to the urothelium. In the reproductive system, mPGES-2 was restricted to the epithelial cells of the testis, epididymis, vas deferens and seminal vesicle in males, and oocytes, stroma cells and corpus luteum of the ovary and epithelial cells of the oviduct and uterus in females. This expression pattern is consistent with an important role for mPGES-2-mediated PGE₂ in urogenital function.