| Authors |
Cheng HF, Zhang MZ, Harris RC
|
| Submitted By |
Raymond Harris on 11/6/2007 |
| Status |
Published |
| Journal |
American journal of physiology. Renal physiology |
| Year |
2006 |
| Date Published |
6/1/2006 |
| Volume : Pages |
290 : F1391 - F1397 |
| PubMed Reference |
16380459 |
| Abstract |
To examine the interaction of nitric oxide (NO) and cyclooxygenase (COX-2) and
the signaling pathway involved, primary cultured rabbit cortical thick ascending
limb (cTAL) were used. In these cells, immunoreactive COX-2 and vasodilatory
prostaglandins were increased by a NO donor, S-nitros-N-acetylpenicillamine
(SNAP; 2.5 +/- 0.3-fold control, n = 6, P < 0.01). SNAP increased expression of
phosphorylated p38 (pp38; 2.4 +/- 0.3-fold control; n = 5; P < 0.01), which was
inhibited by the p38 inhibitor SB-203580 (1.3 +/- 0.1-fold control, n = 5, P <
0.01). SB-203580 inhibited SNAP-induced COX-2 expression [1.4 +/- 0.2-fold
control, n = 6, not significant (NS) vs. control] and levels of PGE2
significantly. In cTAL cells transfected with a luciferase reporter driven by
the wild-type mouse COX-2 promoter, SNAP stimulated luciferase activity, which
was reversed by SB-203580 (control vs. SNAP vs. SNAP + SB-203580: 1.4 +/- 0.2-,
8.3 +/- 1.4-, and 0.4 +/- 0.1-fold control, respectively, n = 4, P < 0.01).
Electrophoretic mobility shift assay indicated that SNAP stimulated nuclear
factor (NF)-kappaB binding activity in cTAL that was also inhibited by the p38
inhibitor. SNAP was not able to stimulate a mutant COX-2 promoter construct that
is not activated by NF-kappaB (0.9 +/- 0.1, 1.2 +/- 0.1, and 1.0 +/- 0.2
respectively, n = 4, NS). Low chloride increased COX-2 expression (2.7 +/-
0.4-fold control, n = 6, P < 0.01) and pp38 expression (2.8 +/- 0.3-fold; n = 5,
P < 0.01), which were reversed by the specific NO synthase (NOS) inhibitor
7-nitroindazole. Administration of a low-salt diet increased immunoreactive
COX-2 and neuronal NOS (nNOS) in the macula densa and surrounding cTAL of
kidneys of wild-type mice but did not significantly elevate COX-2 expression in
nNOS-/- mice. In summary, these studies indicate that, in cTAL, NO can increase
COX-2 expression in cTAL and macula densa through p38-dependent signaling
pathways via activation of NF-kappaB.
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