Dipyridamole inhibits cobalt chloride-induced osteopontin expression in NRK52E cells.
Osteopontin plays a pivotal role in the progression of interstitial fibrosis in renal ischemia. In the present study, rat renal tubular NRK52E cells treated with hypoxia mimetic cobalt chloride (CoCl(2)) increased osteopontin production, and are associated with increased phosphorylation of Akt/PKB (protein kinase B) and p38 mitogen-activated protein kinase (p38MAPK). Furthermore, pretreatment of cells with l-N-acetylcysteine (an antioxidant) inhibited CoCl(2)-stimulated osteopontin protein expression and p38MAPK phosphorylation, but not Akt/PKB phosphorylation. Pretreatment of cells with anti-inflammatory agents celecoxib, tanshinone IIA, and dipyridamole inhibited CoCl(2)-induced osteopontin production paralleled by heme oxygenase-1 (HO-1) induction. Pretreatment of cells with tin protoporphyrin (a HO-1 inhibitor) or hemoglobin (a carbon monoxide scavenging agent) reversed dipyridamole inhibition of osteopontin expression. Moreover, transfection of HO-1 small interfering RNA (siRNA) reduced dipyridamole-stimulated mitogen-activated protein kinase phosphatase-1 (MKP-1) phosphorylation. Conversely, MKP-1 knockdown reversed dipyridamole inhibition of osteopontin expression. Taken together, these data suggest that dipyridamole may inhibit CoCl(2)-induced osteopontin expression through HO-1 induction. Increased HO-1 may catalyze the conversion of heme into carbon monoxide, in turn carbon monoxide activates MKP-1. MKP-1 activation inhibits the p38MAPK signaling pathway that mediates CoCl(2)-induced osteopontin production.
Department of Internal Medicine, Taipei Medical University, Wan Fang Hospital, Taiwan.
Tso-Hsiao
TH
Chen
Chia-Fang
CF
Chang
Shu-Chuan
SC
Yu
Jiueng-Chueng
JC
Wang
Cheng-Hsien
CH
Chen
Paul
P
Chan
Horng-Mo
HM
Lee
D000818:Animals; D055162:Biocatalysis; D002248:Carbon Monoxide / Q000378:metabolism; D002460:Cell Line; D003035:Cobalt / Q000494:pharmacology*; D004176:Dipyridamole / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006418:Heme / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000096:biosynthesis; D007684:Kidney Tubules / Q000166:cytology; D054639:Mitogen-Activated Protein Kinase Phosphatases / Q000378:metabolism; D053495:Osteopontin / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
D017382:Reactive Oxygen Species; D053495:Osteopontin; D003035:Cobalt; D006418:Heme; D004176:Dipyridamole; D002248:Carbon Monoxide; D051547:Heme Oxygenase-1; D054639:Mitogen-Activated Protein Kinase Phosphatases; C018021:cobaltous chloride