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- Title
Combined expression of A1 and A20 achieves optimal protection of renal proximal tubular epithelial cells.
- Authors
Kunter, Uta; Daniel, Soizic; Arvelo, Maria B.; Choi, Jean; Shukri, Tala; Patel, Virendra I.; Longo, Christopher R.; Scali, Salvatore T.; Shrikhande, Gautam; Rocha, Eduardo; Czismadia, Eva; Mottley, Christina; Grey, Shane T.; Floege, Jürgen; Ferran, Christiane; Floege, Jürgen
- Abstract
<bold>Background: </bold>Apoptotic death of renal proximal tubular epithelial cells (RPTECs) is a feature of acute and chronic renal failure. RPTECs are directly damaged by ischemia, inflammatory, and cytotoxic mediators but also contribute to their own demise by up-regulating proinflammatory nuclear factor-kappaB (NF-kappaB)-dependent proteins. In endothelial cells, the Bcl family member A1 and the zinc finger protein A20 have redundant and dual antiapoptotic and anti-inflammatory effects. We studied the function(s) of A1 and A20 in human RPTECs in vitro. <bold>Methods: </bold>Expression of A1 [reverse transcription-polymerase chain reaction (RT-PCR) and A20 (Northern and Western blot analysis)] in RPTECs was evaluated. A1 and A20 were overexpressed in RPTECs by recombinant adenoviral-mediated gene transfer. Their effect upon inhibitor of NFkappaB alpha (IkappaBalpha) degradation (Western blot), NF-kappaB nuclear translocation [electrophoretic mobility shift assay (EMSA)], up-regulation of intercellular adhesion molecule-1 (ICAM-1) [fluorescence-activated cell sorter (FACS)] and monocyte chemoattractant protein-1 (MCP-1) (Northern blot) and apoptosis [terminal deoxynucleotiddyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL)] and FACS analysis of DNA content) was determined. <bold>Results: </bold>A1 and A20 were induced in RPTECs as part of the physiologic response to tumor necrosis factor (TNF). A20, but not A1, inhibited TNF-induced NF-kappaB activation by preventing IkappaBalpha degradation, hence subsequent up-regulation of the proinflammatory molecules ICAM-1 and MCP-1. Unexpectedly, A20 did not protect RPTECs from TNF and Fas-mediated apoptosis while A1 protected against both stimuli. Coexpression of A1 and A20 in RPTECs achieved additive anti-inflammatory and antiapoptotic cytoprotection. <bold>Conclusion: </bold>A1 and A20 exert differential cytoprotective effects in RPTECs. A1 is antiapoptotic. A20 is anti-inflammatory via blockade of NF-kappaB. We propose that A1 and A20 are both required for optimal protection of RPTECs from apoptosis (A1) and inflammation (A20) in conditions leading to renal damage.
- Subjects
APOPTOSIS; EPITHELIAL cells; CHRONIC kidney failure; ACUTE kidney failure; ISCHEMIA; NF-kappa B; PROTEINS; RNA analysis; ANTIGENS; BIOCHEMISTRY; CELL culture; COMPARATIVE studies; GENE expression; HISTOCOMPATIBILITY antigens; INFLAMMATORY mediators; KIDNEY tubules; NEPHRITIS; PHENOMENOLOGY; RESEARCH methodology; MEDICAL cooperation; RESEARCH; RESEARCH funding; TUMOR necrosis factors; DNA-binding proteins; EVALUATION research; NUCLEAR proteins; SIGNAL peptides; PHYSIOLOGY; CELL physiology
- Publication
Kidney International, 2005, Vol 68, Issue 4, p1520
- ISSN
0085-2538
- Publication type
journal article
- DOI
10.1111/j.1523-1755.2005.00564.x