Apr 18, 2018 - shock response on the level of the heat shock transcription factor 1 (HSF-1). Methods: The induction of the heat shock response in human ...
Nephrology Dialysis Transplantation 31 (Supplement 1): i235–i245, 2016 doi:10.1093/ndt/gfw171.4
PERITONEAL DIALYSIS - 1 SP433
PERITONEAL DIALYSIS FLUID CAUSE INADEQUATE ACTIVATION OF HSF1 BY RELEVANT STRESSORS; A NOVEL PATHOMECHANISM?
Rebecca Herzog1,2,3, Klaus Kratochwill1,2, Hans Lederhuber1, Lilian Kuster3, Krisztina Heindl-Rusai1, Elisabeth Salzer1, Bettina Bidmon4, Anton Lichtenauer3 and Christoph Aufricht1 1 Medical University of Vienna, Pediatric Nephrology, Vienna, AUSTRIA, 2Christian Doppler Laboratory for Molecular Stress Research in Peritoneal Dialysis, Medical University of Vienna, Vienna, AUSTRIA, 3Zytoprotec, Research, Vienna, AUSTRIA, 4 Medical University of Vienna, Pediatric Gastroenterology, Vienna, AUSTRIA Introduction and Aims: Chronic exposure to peritoneal dialysis fluid (PDF) causes injury of mesothelial cells but also induces cytoprotective mechanisms. Recent studies, however, suggest that PDF blocks the heat shock response, one of the evolutionary most important stress responses. The resultant increased vulnerability of the peritoneal cells could lead to progressing fibrosis of the peritoneal membrane during PD. This study aims to identify the molecular mechanisms leading to the PDF-induced inadequate heat shock response on the level of the heat shock transcription factor 1 (HSF-1).
Methods: The induction of the heat shock response in human mesothelial cells (MeT-5A) was analyzed using combined in-vitro models of PDF exposure and heat stress as the gold standard. In addition single cytotoxic components of PDF, like glucose degradations products (GDP) and acidosis as well as the impact of cytoprotective additives were investigated. The status of HSF-1 activation, cellular Hsp72 expression, the stress-proteome and viability of the mesothelial cells were analyzed. HSF-1 regulation was analyzed by use of nuclear shift analysis, the phosphorylation status, DNA-binding capacity and Hsp72 induction among the different stressors. Results: Compared to heat, PDF leads to increased lethality but decreased Hsp72 expression. A concurrent blockage of the nuclear shift, phosphorylation and DNA-binding of HSF-1 with reduced activity of the promotor was found. The inadequate HSF-1 activation could be unblocked by a neutral pH, filter-sterilized PDF (without GDPs) or addition of alanyl-glutamine. The HSF-1 blocking caused by the acidosis was associated with activation of GSK-3β, while the GDPs directly interfered with HSF-1 promotor activity. Conclusions: The PDF-mediated inadequate induction of the cellular heat shock response represents a new pathomechanism in PD. Our results demonstrate that the cytotoxic factors such as acidosis and GDPs of PDF lead to a HSF-1 block via different molecular mechanisms resulting in a reduction of the heat shock response and increased vulnerability of mesothelial cells exposed to PDF which could be restored by addition of alanyl-glutamine. In further studies the role of post-translational modifications of HSF-1 and their influence on the regulation of the heat shock response in PD will be analyzed.
© The Author 2016. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.
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