Abstract: SA-PO933
Intra-Nuclear Binding of NFAT5/TonEBP to ß-Catenin Is a Key Process of Hypertonicity-Induced Phenotype Transition of Peritoneal Mesothelial Cells (MCs)
Session Information
- Dialysis: Peritoneal Dialysis - III
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Dialysis
- 703 Dialysis: Peritoneal Dialysis
Authors
- Kang, Duk-Hee, Ewha University College of Medicine, Seoul, Korea (the Republic of)
- Kang, Hyun-Jung, Ewha Womans University, Seoul, Korea (the Republic of)
- Ryu, Eun sun, Ewha Womans University School of Medicine, Seoul, Korea (the Republic of)
- Kim, Dal-ah, Ewha Womans University Medical Center, Seoul, seoul, Korea (the Republic of)
Background
Epithelial-to-mesenchymal transition (EMT) of MCs is an early mechanism of peritoneal fibrosis in peritoneal dialysis. Nuclear Factor of Activated T Cells-5 (NFAT5), also known as TonEBP, is a transcriptional factor that enables cellular adaptation to hypertonic osmotic stress. Recent data demonstrated the role of NFAT5/TonEBP in phenotype transition of cancer cells. The aim of this study is to investigate whether NFAT5/TonEBP is involved in hypertonicity-induced EMT of MCs and to identify the potential mechanisms of NFAT5/TonEBP-mediated peritoneal EMT.
Methods
The expressions of NFAT5/TonEBP, other osmotic stress-related genes including sodium-myoinositol cotransporter (SMIT), betaine/γ-aminobutyric acid transporter (BGT1) and aldose reductase (AR) and nuclear translocation of β-catenin were evaluated by real-time PCR and western blotting. EMT was evaluated by morphological changes of MCs and the expressions of E-cadherin and α-SMA after stimulation of high glucose (HG, 30-120 mM) and mannitol (30-120 mM). E-cadherin promoter activity was confirmed by luciferase assay. The interaction between TonEBP and β-catenin was analyzed by immunoprecipitation.
Results
Both HG or Mannitol enhanced the expression of NFAT5/TonEBP as well as SMIT, BGT1 and AR at transcriptional and translational levels from the concentration of 30 mM. HG induced EMT of MCs, however mannitol did not show the evidence of EMT even at the concentration of 120 mM. HG (>30 mM) induced nuclear translocation of NFAT5/TonEBP which was associated with an enhanced binding to β-catenin. Mannitol also promoted nuclear translocation of NFAT5/TonEBP only at the highest concentration we tested (120 mM), however it was not associated with intra-nuclear binding of NFAT5/TonEBP to β-catenin. In contrast to persistent increase in intra-nuclear β-catenin in HG-exposed MCs, there was only a transient increase in β-catenin with 120 mM of mannitol at 1 hour. HG decreased E-cadherin promoter activity whereas mannitol did not alter the transcription of E-cadherin.
Conclusion
The role of NFAT5/TonEBP as a mediator of peritoneal EMT is demonstrated in this study for the first time. Not the increased expression of NFAT5/TonEBP per se but intra-nuclear translocation with binding to β-catenin is a key mechanism by which NFAT5/TonEBP induced EMT of MCs.