[Expression of cyclooxygenase-2 in a mouse macula densa cell lines and signal transduction of NF-kappaB and AP-1].
OBJECTIVE
To evaluate the effect of low salt (LS) on the expression of cyclooxygenase-2 (COX-2) and the activity of nuclear factor kappa B (NF-kappaB) and activator protein-1 (AP-1) in the mouse macula densa derived (MMDD1) cell line.


METHODS
MMDD1 cells were transfected with luciferase reporter plasmid containing AP-1 or NF-kappaB. Luciferase reporter assay was used to evaluate the effect of normal salt (NS) and low salt (LS) on the activities of NF-kappaB and AP-1. The changes of COX-2 expression were examined by RT-PCR. The expression of p-p38 MAPK, p-p44/42, c-Jun, c-Fos, and COX-2 in MMDD1 cells were analyzed by Western blot.


RESULTS
The expressions of COX-2 mRNA and protein in MMDD1 cells were significantly increased by LS (P < 0.01). Phosphorylated p38 and p44/42 MAP kinase were significantly increased by treatment at 180 min (P < 0.01). The up-regulated COX-2 protein expression with LS were significantly reduced with SB 203580 (p38 inhibitors) and PD-98059 (p44/42 inhibitors) (P < 0.01). The expressions of c-Jun and c-Fos were increased by LS. The luciferase activities of AP-1 and NF-kappaB were stimulated in LS (P < 0.01), the up-regulated luciferase activities were attenuated by PDTC at 25 micromol/L (NF-kappaB inhibitor) and curcumin at 20 micromol/L (AP-1 inhibitor) (P < 0.01). LS altered COX-2 mRNA abundance and protein expression were decreased in treatment with PDTC at 25 micromol/L, curcumin at 20 micromol/L (P < 0.01).


CONCLUSIONS
LS can induce the expression of COX-2 in MMDD1 cells, which may be involved in the activation of p38 MAP kinase, p44/42 kinase, AP-1, and NF-kappaB pathways.
Liu
Dong-Yan
DY
Department of Nephrology, PUMC Hospital, CAMS and PUMC, Beijing 100730, China.
Li
Xue-Wang
XW
Li
Hang
H
Li
Xue-Mei
XM
Ye
Weng-Ling
WL
D000818:Animals; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D007668:Kidney / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000378:metabolism*
D016328:NF-kappa B; D018808:Transcription Factor AP-1; D051546:Cyclooxygenase 2