QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: jpet.106.102574v1 318/2/782    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wolff, N. A. Articles by Thévenod, F. Search for Related Content PubMed PubMed Citation Articles by Wolff, N. A. Articles by Thévenod, F.

TOXICOLOGY

Megalin-Dependent Internalization of Cadmium-Metallothionein and Cytotoxicity in Cultured Renal Proximal Tubule Cells

Department of Physiology and Pathophysiology, Faculty of Medicine, University of Witten/Herdecke, Witten, Germany (N.A.W., M.A., F.T.); and Institut National de la Santé et de la Recherche Médicale U.538, Centre Hospitalo-Universitaire Saint Antoine, Paris, France (P.J.V.)

Chronic cadmium (Cd²⁺) exposure results in renal proximal tubular cell damage. Delivery of Cd²⁺ to the kidney occurs mainly as complexes with metallothionein-1 (molecular mass 7 kDa), freely filtered at the glomerulus. For Cd²⁺ to gain access to the proximal tubule cells, these complexes are thought to be internalized via receptors for small protein ligands, such as megalin and cubilin, followed by release of Cd²⁺ from metallothionein-1 in endosomal/lysosomal compartments. To investigate the role of megalin in renal cadmium-metallothionein-1 reabsorption, megalin expression and dependence of cadmium-metallothionein-1 internalization and cytotoxicity on megalin were studied in a renal proximal tubular cell model (WKPT-0293 Cl.2 cells). Expression of megalin was detected by reverse transcriptase-polymerase chain reaction and visualized by immunofluorescence both at the cell surface (live staining) and intracellularly (permeabilized cells). Internalization of Alexa Fluor 488-coupled metallothionein-1 was concentration-dependent, saturating at approximately 15 µM. At 14.3 µM, metallothionein-1 uptake could be significantly attenuated by 30.9 ± 6.6% (n = 4) by 1 µM of the receptor-associated protein (RAP) used as a competitive inhibitor of cadmium-metallothionein-1 binding to megalin and cubilin. Consistently, cytotoxicity of a 24-h treatment with 7.14 µM cadmium-metallothionein-1 was significantly reduced by 41.0 ± 7.6%, 61.6 ± 3.4%, and 26.2 ± 1.8% (n = 4-5 each) by the presence of 1 µM RAP, 400 µg/ml anti-megalin antibody, or 5 µM of the cubilin-specific ligand, apo-transferrin, respectively. Cubilin expression in proximal tubule cells was also confirmed at the mRNA and protein level. The data indicate that renal proximal tubular cadmium-metallothionein-1 uptake and cell death are mediated at least in part by megalin.

Address correspondence to: Dr. Frank Thévenod, Department of Physiology and Pathophysiology, University of Witten/Herdecke, Faculty of Medicine, Stockumer Strasse 12, D-58448 Witten, Germany. E-mail: frank.thevenod{at}uni-wh.de

This article has been cited by other articles:

				R. S. Chung, M. Penkowa, J. Dittmann, C. E. King, C. Bartlett, J. W. Asmussen, J. Hidalgo, J. Carrasco, Y. K. J. Leung, A. K. Walker, et al. Redefining the Role of Metallothionein within the Injured Brain: EXTRACELLULAR METALLOTHIONEINS PLAY AN IMPORTANT ROLE IN THE ASTROCYTE-NEURON RESPONSE TO INJURY J. Biol. Chem., May 30, 2008; 283(22): 15349 - 15358. [Abstract] [Full Text] [PDF]

				A. Brandes, O. Oehlke, A. Schumann, S. Heidrich, F. Thevenod, and E. Roussa Adaptive redistribution of NBCe1-A and NBCe1-B in rat kidney proximal tubule and striated ducts of salivary glands during acid-base disturbances Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2007; 293(6): R2400 - R2411. [Abstract] [Full Text] [PDF]

				G. Jacquillet, O. Barbier, I. Rubera, M. Tauc, A. Borderie, M. C. Namorado, D. Martin, G. Sierra, J. L. Reyes, P. Poujeol, et al. Cadmium causes delayed effects on renal function in the offspring of cadmium-contaminated pregnant female rats Am J Physiol Renal Physiol, November 1, 2007; 293(5): F1450 - F1460. [Abstract] [Full Text] [PDF]

				W.-K. Lee, B. Torchalski, and F. Thevenod Cadmium-induced ceramide formation triggers calpain-dependent apoptosis in cultured kidney proximal tubule cells Am J Physiol Cell Physiol, September 1, 2007; 293(3): C839 - C847. [Abstract] [Full Text] [PDF]

				G. Ciarimboli Unraveling the ceramide-calpain-caspase connection in cadmium-induced apoptosis: a novel role for ceramides as activators of calpains. Focus on "Cadmium-induced ceramide formation triggers calpain-dependent apoptosis in cultured kidney proximal tubule cells" Am J Physiol Cell Physiol, September 1, 2007; 293(3): C837 - C838. [Full Text] [PDF]

				M. Abouhamed, N. A. Wolff, W.-K. Lee, C. P. Smith, and F. Thevenod Knockdown of endosomal/lysosomal divalent metal transporter 1 by RNA interference prevents cadmium-metallothionein-1 cytotoxicity in renal proximal tubule cells Am J Physiol Renal Physiol, September 1, 2007; 293(3): F705 - F712. [Abstract] [Full Text] [PDF]

				M. Abbate, C. Zoja, and G. Remuzzi How Does Proteinuria Cause Progressive Renal Damage? J. Am. Soc. Nephrol., November 1, 2006; 17(11): 2974 - 2984. [Abstract] [Full Text] [PDF]