Molecular identification of cytosolic prostaglandin E2 synthase that is functionally coupled with cyclooxygenase-1 in immediate prostaglandin E2 biosynthesis.
Here we report the molecular identification of cytosolic glutathione (GSH)-dependent prostaglandin (PG) E(2) synthase (cPGES), a terminal enzyme of the cyclooxygenase (COX)-1-mediated PGE(2) biosynthetic pathway. GSH-dependent PGES activity in the cytosol of rat brains, but not of other tissues, increased 3-fold after lipopolysaccharide (LPS) challenge. Peptide microsequencing of purified enzyme revealed that it was identical to p23, which is reportedly the weakly bound component of the steroid hormone receptor/hsp90 complex. Recombinant p23 expressed in Escherichia coli and 293 cells exhibited all the features of PGES activity detected in rat brain cytosol. A tyrosine residue near the N terminus (Tyr(9)), which is known to be critical for the activity of cytosolic GSH S-transferases, was essential for PGES activity. The expression of cPGES/p23 was constitutive and was unaltered by proinflammatory stimuli in various cells and tissues, except that it was increased significantly in rat brain after LPS treatment. cPGES/p23 was functionally linked with COX-1 in marked preference to COX-2 to produce PGE(2) from exogenous and endogenous arachidonic acid, the latter being supplied by cytosolic phospholipase A(2) in the immediate response. Thus, functional coupling between COX-1 and cPGES/p23 may contribute to production of the PGE(2) that plays a role in maintenance of tissue homeostasis.
Tanioka
T
T
Department of Health Chemistry, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142, Japan.
Nakatani
Y
Y
Semmyo
N
N
Murakami
M
M
Kudo
I
I
D016475:3T3 Cells; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001921:Brain / Q000201:enzymology*; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D051545:Cyclooxygenase 1; D003600:Cytosol / Q000201:enzymology; D015232:Dinoprostone / Q000096:biosynthesis*; D004926:Escherichia coli; D006367:HeLa Cells; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism*; D007739:L Cells; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D016297:Mutagenesis, Site-Directed; D010006:Osteoblasts; D000071876:Prostaglandin-E Synthases; D011451:Prostaglandin-Endoperoxide Synthases / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D007527:Isoenzymes; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D011994:Recombinant Proteins; D051545:Cyclooxygenase 1; C496511:PTGS1 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; C496513:Ptgs1 protein, rat; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases; C000605868:Ptges3 protein, mouse; D015232:Dinoprostone