Endothelin-1 Induces NF-κB via Two Independent Pathways in Human Renal Tubular Epithelial CellsGerstung M.a · Roth T.a · Dienes H.-P.a · Licht C.b · Fries J.W.U.a
aDepartment of Pathology, University of Cologne, Cologne, Germany, and bDivision of Nephrology, Hospital for Sick Children, Toronto, Ont., Canada
Background: Endothelin-1 (ET-1) is a major transcriptional activator of renal proximal tubule cells acting in an autocrine and paracrine manner. In animal studies, ET-1 has been implicated in progressive renal interstitial fibrosis by promoting gene expression, possibly via the inflammatory NF-ĸB signal pathway. While ET-1-dependent mechanisms of signal transduction have been studied mainly in tumor cell lines, we analyzed the mechanism of ET-1-induced, NF-ĸB-mediated target gene activation in proximal tubule cells. Methods: Human renal proximal tubule cells were stimulated with ET-1 and gene expression analyzed by protein microarray, Western blot, non-radioactive electromobility shift assay, and quantitative real-time polymerase chain reaction. Results: Activation of NF-ĸB occurs only via an ET-1-specific type A receptor (not type B as in animals). Induction can be blocked by bosentan, and endothelin-A but not endothelin-B receptor-specific antagonists. Protein microarray screening shows activation of two independent cascades (via the endothelin-A receptor, or via diacylglycerol) leading to NF-ĸB induction. The independent induction is also reflected by target gene expression such as the vascular cell adhesion molecule-1, interleukin-6, and fractalkine at different time points. Conclusion: Thus prohibiting ET-1-mediated gene transcription necessitates blocking of NF-ĸB and diacylglycerol signal transduction in proximal tubule cells.
© 2007 S. Karger AG, Basel
This work was supported by a grant from the Imhoff-Stiftung, in part from a post-doctoral fellowship from the Cologne Fortune program of the University of Cologne to C.L., and private donations. M.G. is the recipient of a doctoral research fellowship from the Cologne Fortune program of the University of Cologne.
Received: January 23, 2007
Accepted: March 19, 2007
Published online: April 25, 2007
Number of Print Pages : 7
Number of Figures : 4, Number of Tables : 0, Number of References : 31
American Journal of Nephrology
Vol. 27, No. 3, Year 2007 (Cover Date: May 2007)
Journal Editor: Bakris, G. (Chicago, Ill.)
ISSN: 0250–8095 (print), 1421–9670 (Online)
For additional information: http://www.karger.com/AJN