Puromycin induces reversible proteinuric injury in transgenic mice expressing cyclooxygenase-2 in podocytes.
Previous studies from our own group and others have demonstrated that cyclooxygenase-2 (COX-2) inhibitors could reduce proteinuria in some experimental models of progressive renal disease. To investigate a possible role of COX-2 in podocytes during the course of self-limited glomerular injury, we administered puromycin nucleoside (PAN) on day 1 (15 mg/100 g BW) and day 3 (30 mg/100 g BW) to wild-type and transgenic mice with podocyte-specific COX-2 expression driven by a nephrin promoter. An additional group received both PAN and the COX-2-specific inhibitor, SC58236 (6 mg/l in drinking water). There was no significant difference in the albumin (microg)/creatinine (mg) ratio between wild-type (26.3 +/- 4.2, n = 8) and transgenic (28.9 +/- 2.3, n = 8) mice under baseline conditions. PAN induced significant albuminuria only in the transgenic mice with a peak at day 3: 72.1 +/- 8.9 microg/mg creatinine (n = 12, p < 0.05, compared with basal level), which remitted by day 10 (37.4 +/- 4.4 microg/mg, n = 7, p < 0.05, compared with day 3). Electron microscopy demonstrated that PAN caused 56.7 +/- 4.2% foot process effacement in transgenic mice compared with 38.8 +/- 4.1% in wild type at day 3. PAN increased immunoreactive COX-2 in glomeruli from transgenic mice (day 3: 1.47 +/- 0.08 fold; day 10: 1.25 +/- 0.16 fold, n = 5-9, p < 0.05 compared with basal level), which was restricted to podocytes. Real time PCR indicated that endogenous COX-2 mRNA increased (2.6 +/- 0.1 fold of wild-type control at day 3 and 2.2 +/- 0.2 at day 10, n = 4, p < 0.05), while the nephrin-driven COX-2 mRNA was unchanged. Nephrin mRNA and protein expression were decreased by PAN in the transgenic mice. The COX-2-specific inhibitor, SC58236, reduced foot process effacement in transgenic mice administered PAN to 21.7 +/- 5.2% and significantly reduced the albuminuria at day 3 (42.2 +/- 3.8, n = 13, p < 0.05 compared with untreated) without significantly altering COX-2 expression. In summary, in transgenic mice with podocyte COX-2 overexpression, PAN increased albuminuria and induced foot process fusion. Thus, increased COX-2 expression increased podocyte susceptibility to further injury.
Jo
Young-Il
YI
Division of Nephrology, George M. O'Brien Kidney and Urologic Diseases Center, Vanderbilt University School of Medicine and Nashville Veterans Affairs Hospital, Nashville, Tenn 37232, USA.
Cheng
Huifang
H
Wang
Suwan
S
Moeckel
Gilbert W
GW
Harris
Raymond C
RC
D000419:Albuminuria / Q000139:chemically induced / Q000188:drug therapy / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D000818:Animals; D051546:Cyclooxygenase 2 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D004790:Enzyme Induction; D005813:Genes, Synthetic; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D050199:Podocytes / Q000201:enzymology* / Q000648:ultrastructure; D011692:Puromycin Aminonucleoside / Q000633:toxicity*; D011720:Pyrazoles / Q000494:pharmacology / Q000627:therapeutic use; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000502:physiology; D013449:Sulfonamides / Q000494:pharmacology / Q000627:therapeutic use; D000096926:Benzenesulfonamides
D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D008565:Membrane Proteins; D011692:Puromycin Aminonucleoside; D011720:Pyrazoles; D011993:Recombinant Fusion Proteins; D013449:Sulfonamides; C119130:4-(5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)benzenesulfonamide; D000096926:Benzenesulfonamides; C113267:nephrin; C077623:Ptgs2 protein, mouse