Osmotic Diuretics Induce Adenosine A1 Receptor Expression and Protect Renal Proximal Tubular Epithelial Cells against Cisplatin-mediated Apoptosis

• Published in: The Journal of biological chemistry Vol. 279; no. 41; pp. 43157 - 43167
• Main Authors: Pingle, Sandeep C, Mishra, Snigdha, Marcuzzi, Adriana, Bhat, Satyanarayan G, Sekino, Yuko, Rybak, Leonard P, Ramkumar, Vickram
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 08.10.2004
• Subjects: Allopurinol - metabolism; Animals; Annexin A5 - pharmacology; Apoptosis; Blotting, Northern; Cell Line; Cell Nucleus - metabolism; Cisplatin - pharmacology; Coloring Agents - pharmacology; Diuretics - pharmacology; Dose-Response Relationship, Drug; Epithelial Cells - metabolism; Immunohistochemistry; Kidney - pathology; Kidney Cortex - drug effects; Kidney Cortex - metabolism; Kidney Tubules - cytology; Kidney Tubules - metabolism; Kidney Tubules - pathology; Kidney Tubules, Collecting - metabolism; Luciferases - metabolism; Male; Mannitol - pharmacology; Mice; Mice, Inbred C57BL; Microscopy, Fluorescence; Necrosis; NF-kappa B - metabolism; Polymerase Chain Reaction; Protein Binding; Reactive Oxygen Species; Receptor, Adenosine A1 - biosynthesis; RNA - metabolism; Sodium Chloride - pharmacology; Swine; Transcription, Genetic; Up-Regulation; Xanthine Oxidase - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M405666200

Osmotic diuretics are used successfully to alleviate acute tubular necrosis (ATN) produced by chemotherapeutic agents and aminoglycoside antibiotics. The beneficial action of these agents likely involves rapid elimination of the nephrotoxic agents from the kidney by promoting diuresis. Adenosine A 1 receptor (A 1 AR) subtype present on renal proximal tubular epithelial and cortical collecting duct cells mediates the antidiuretic and cytoprotective actions of adenosine. These receptors are induced by activation of nuclear factor (NF)-κB, a transcription factor reported to mediate hyperosmotic stress-induced cytoprotection in renal medullary cells. In this study, we tested the hypothesis that induction of the A 1 AR in renal proximal tubular cells by NF-κB contributes to the cytoprotection afforded by osmotic diuretics. Exposure of porcine renal proximal tubular epithelial (LLC-PK 1 ) cells to mannitol or NaCl produced a significant increase in A 1 AR. This increase was preceded by adenosine release and NF-κB activation. Expression of an IκB-α mutant, which acts as a superrepressor of NF-κB, abrogated the increase in A 1 AR. Cells exposed to mannitol demonstrated increased reactive oxygen species (ROS) generation, which was attenuated by inhibiting xanthine oxidase with allopurinol. Allopurinol attenuated both the increase in A 1 AR expression and NF-κB activation produced by osmotic diuretics, indicating a role of adenosine metabolites in these processes. Treatment of LLC-PK 1 cells with cisplatin (8 μ m ) resulted in apoptosis, which was attenuated by mannitol but exacerbated by selective A 1 AR blockade. Administration of mannitol to mice increases A 1 AR expression and activation of NF-κB in renal cortical sections. Taken together, these data provide novel mechanisms of nephroprotection by osmotic diuretics, involving both activation and induction of the A 1 AR, the latter mediated through activation of a xanthine oxidase pathway leading to ROS generation and promoting activation of NF-κB.