Molecular evidence for an involvement of organic anion transporters (OATs) in aristolochic acid nephropathy.
Aristolochic acid (AA), present in Aristolochia species, is the major causative agent in the development of severe renal failure and urothelial cancers in patients with AA nephropathy. It may also be a cause of Balkan endemic nephropathy. Epithelial cells of the proximal tubule are the primary cellular target of AA. To study whether organic anion transporters (OATs) expressed in proximal tubule cells are involved in uptake of AA, we used human epithelial kidney (HEK293) cells stably expressing human (h) OAT1, OAT3 or OAT4. AA potently inhibited the uptake of characteristic substrates, p-aminohippurate for hOAT1 and estrone sulfate for hOAT3 and hOAT4. Aristolochic acid I (AAI), the more cytotoxic and genotoxic AA congener, exhibited high affinity for hOAT1 (K(i)=0.6 microM) as well as hOAT3 (K(i)=0.5 microM), and lower affinity for hOAT4 (K(i)=20.6 microM). Subsequently, AAI-DNA adduct formation (investigated by (32)P-postlabelling) was used as a measure of AAI uptake. Significantly higher levels of adducts occurred in hOAT-expressing cells than in control cells: this effect was abolished in the presence of the OAT inhibitor probenecid. In Xenopus laevis oocytes hOAT-mediated efflux of p-aminohippurate was trans-stimulated by extracellular AA, providing further molecular evidence for AA translocation by hOATs. Our study indicates that OATs can mediate the uptake of AA into proximal tubule cells and thereby participate in kidney cell damage by this toxin.
Bakhiya
Nadiya
N
German Institute of Human Nutrition (DIfE) Potsdam-Rehbrücke, Department of Nutritional Toxicology, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany.
Arlt
Volker M
VM
Bahn
Andrew
A
Burckhardt
Gerhard
G
Phillips
David H
DH
Glatt
Hansruedi
H
D000818:Animals; D034341:Aristolochic Acids / Q000378:metabolism* / Q000633:toxicity*; D002478:Cells, Cultured; D018736:DNA Adducts / Q000187:drug effects / Q000378:metabolism; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D007674:Kidney Diseases / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D009865:Oocytes / Q000378:metabolism; D027361:Organic Anion Transporters / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011339:Probenecid / Q000494:pharmacology; D012076:Renal Agents / Q000494:pharmacology; D014982:Xenopus laevis; D010130:p-Aminohippuric Acid / Q000378:metabolism
D034341:Aristolochic Acids; D018736:DNA Adducts; D027361:Organic Anion Transporters; D012076:Renal Agents; C000228:aristolochic acid I; D011339:Probenecid; D010130:p-Aminohippuric Acid