Low chloride stimulation of prostaglandin E2 release and cyclooxygenase-2 expression in a mouse macula densa cell line.
Reducing luminal NaCl concentration in the macula densa region of the nephron stimulates renin secretion, and this response is blocked by a specific inhibitor of cyclooxygenase-2 (COX-2) (Traynor, T. R., Smart, A., Briggs, J. P., and Schnermann, J. (1999) Am. J. Physiol. Renal Physiol. 277, F706-710). To study whether low NaCl activates COX-2 activity or expression we clonally derived a macula densa cell line (MMDD1 cells) from SV-40 transgenic mice using fluorescence-activated cell sorting of renal tubular cells labeled with segment-specific fluorescent lectins. MMDD1 cells express COX-2, bNOS, NKCC2, and ROMK, but not Tamm-Horsfall protein, and showed rapid (86)Rb(+) uptake that was inhibited by a reduction in NaCl concentration and by bumetanide or furosemide. Isosmotic exposure of MMDD1 cells to low NaCl (60 mm) caused a prompt and time-dependent stimulation of prostaglandin E(2) (PGE(2)) release that was prevented by the COX-2 specific inhibitor NS-398 (10 microm). Reducing NaCl to 60 and 6 mm for 16 h increased COX-2 expression in a chloride-dependent fashion. Low NaCl phosphorylated p38 kinase within 30 min and ERK1/2 kinases within 15 min without changing total MAP kinase levels. Low NaCl-stimulated PGE(2) release and COX-2 expression was inhibited by SB 203580 and PD 98059 (10 microm), inhibitors of p38 and ERK kinase pathways. We conclude that low chloride stimulates PGE(2) release and COX-2 expression in MMDD1 cells through activation of MAP kinases.
Yang
T
T
NIDDK and NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Park
J M
JM
Arend
L
L
Huang
Y
Y
Topaloglu
R
R
Pasumarthy
A
A
Praetorius
H
H
Spring
K
K
Briggs
J P
JP
Schnermann
J
J
D000818:Animals; D030801:Animals, Genetically Modified; D002460:Cell Line; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D007672:Kidney Cortex / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride / Q000494:pharmacology*
D007527:Isoenzymes; D012965:Sodium Chloride; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D020928:Mitogen-Activated Protein Kinases; D015232:Dinoprostone