Endothelin-1 induces NF-kappaB via two independent pathways in human renal tubular epithelial cells.
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-kappaB 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-kappaB-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-kappaB 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-kappaB 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.


CONCLUSIONS
Thus prohibiting ET-1-mediated gene transcription necessitates blocking of NF-kappaB and diacylglycerol signal transduction in proximal tubule cells.
Gerstung
Melanie
M
Department of Pathology, University of Cologne, Cologne, Germany.
Roth
Tanja
T
Dienes
Hans-Peter
HP
Licht
Christoph
C
Fries
Jochen W U
JW
D002478:Cells, Cultured; D004075:Diglycerides / Q000378:metabolism; D019332:Endothelin-1 / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D007249:Inflammation / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
D004075:Diglycerides; D019332:Endothelin-1; D016328:NF-kappa B; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B