title: Membrane-associated PGE synthase-1 (mPGES-1) is coexpressed with both COX-1 and COX-2 in the kidney.
abstract: BACKGROUND
  Prostaglandin E2 (PGE2) plays an important role in many physiologic and pathophysiologic processes in the kidney. Multiple enzymes are involved in PGE2 biosynthesis, including phospholipases, cyclooxygenases (COX), and the PGE2 synthases (PGES). The present studies were aimed at determining the intrarenal localization of mPGES-1 and whether it is coexpressed with COX-1 or COX-2.
  
  
  METHODS
  Rabbit mPGES-1 and COX-1 cDNAs were cloned using reverse transcription-polymerase chain reaction (RT-PCR) and screening a cDNA library. RNase protection assay and immunoblotting were used to examine mPGES-1 expression levels. In situ hybridization and immunostaining were used to determine the intrarenal localization of mPGES-1 and cyclooxygenases.
  
  
  RESULTS
  Rabbit mPGES-1 shares high sequence similarity to the human homolog. Nuclease protection studies showed that the kidney expresses among the highest level of mPGES-1 of any rabbit tissue. In situ hybridization showed COX-1 and mPGES-1 mRNA was highly expressed in renal medullary collecting ducts (MCD), and to a lesser extent in cortical collecting ducts (CCD). Fainter mPGES-1 expression was also observed in macula densa (MD) and medullary interstitial cells (RMICs), where COX-2 is highly expressed. Double-labeling studies (immunostaining plus in situ hybridization) and immunohistochemistry of mouse tissues confirmed that mPGES-1 predominantly colocalizes with COX-1 in distal convoluted tubule (DCT), CCD, and MCD, and is coexpressed with COX-2 at lower levels in MD and RMICs.
  
  
  CONCLUSIONS
  Together, these studies suggest mPGES-1 colocalizes with both COX-1 and COX-2 to mediate the biosynthesis of PGE2 in the kidney.
authors.affiliation: Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
authors.forename: André
authors.initials: A
authors.lastname: Schneider
authors.forename: YaHua
authors.initials: Y
authors.lastname: Zhang
authors.forename: Mingzhi
authors.initials: M
authors.lastname: Zhang
authors.forename: Wendell J
authors.initials: WJ
authors.lastname: Lu
authors.forename: Reena
authors.initials: R
authors.lastname: Rao
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Fan
authors.forename: Reyadh
authors.initials: R
authors.lastname: Redha
authors.forename: Linda
authors.initials: L
authors.lastname: Davis
authors.forename: Richard M
authors.initials: RM
authors.lastname: Breyer
authors.forename: Raymond
authors.initials: R
authors.lastname: Harris
authors.forename: YouFei
authors.initials: Y
authors.lastname: Guan
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Breyer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002462:Cell Membrane / Q000201:enzymology*; D003001:Cloning, Molecular; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D018076:DNA, Complementary; D005260:Female; D019746:Intramolecular Oxidoreductases; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D007679:Kidney Medulla / Q000166:cytology / Q000201:enzymology; D007685:Kidney Tubules, Collecting / Q000201:enzymology; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D014018:Tissue Distribution
chemical_list: D018076:DNA, Complementary; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D019746:Intramolecular Oxidoreductases; C492485:membrane-associated PGE synthase-1, rabbit