Nitric oxide stimulates COX-2 expression in cultured collecting duct cells through MAP kinases and superoxide but not cGMP.
Collecting ducts are a major site of renal production and action of both prostaglandins and nitric oxide. Experiments were undertaken to examine whether nitric oxide regulates cyclooxygenase (COX)-2 expression and PGE(2) release in cultured collecting duct cells. In mIMCD-K2 cells, sodium nitroprusside (SNP) in the 50- to 800-microM range induced a marked dose- and time-dependent increase in COX-2 protein levels, determined by immunoblotting, and the induction was detectable at 4 h. This was preceded by induction of COX-2 mRNA as determined by real-time-RT-PCR. The COX-2 induction was accompanied by a significant rise in PGE(2) release as determined by enzyme immunoassay. S-nitroso-N-acetylpenicillamine (SNAP) had a similar stimulatory effect on COX-2 expression and PGE(2) release. 8-bromo-cGMP (200 microM) had no effect on COX-2 expression. The SNP-stimulated COX-2 expression was not affected by the guanylyl cyclase inhibitor methylene blue or the protein kinase G inhibitor KT-5823 (2.0 microM). In contrast, the SNP-stimulated COX-2 expression was significantly reduced by either the Erk1/2 inhibitor PD-98059 or the P38 inhibitor SB-203580 and was abolished by combination of the two kinase inhibitors. The stimulation was also significantly blocked by the SOD mimetic tempol. Thus we conclude that NO stimulates COX-2 expression in collecting duct cells through mechanisms involving MAP kinase and superoxide, but not cGMP.
Yang
Tianxin
T
Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City, Utah 84148, USA. tianxin.yang@hsc.utah.edu
Zhang
Aihua
A
Pasumarthy
Anita
A
Zhang
Lihong
L
Warnock
Zachary
Z
Schnermann
Jurgen B
JB
D000818:Animals; D002460:Cell Line; D006152:Cyclic GMP / Q000502:physiology; D051546:Cyclooxygenase 2 / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D051381:Rats; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology*; D013481:Superoxides / Q000378:metabolism*
D020030:Nitric Oxide Donors; D013481:Superoxides; D026423:S-Nitroso-N-Acetylpenicillamine; D051546:Cyclooxygenase 2; D020928:Mitogen-Activated Protein Kinases; D006152:Cyclic GMP