Serum response factor accelerates the high glucose-induced Epithelial-to-Mesenchymal Transition (EMT) via snail signaling in human peritoneal mesothelial cells.

Lijie He,Guoshang Xu,Shiren Sun,Meilan Zhou,Wei Liang,Weijuan Lou,Xiangmei Chen,Rong Li,Lihua Ji,Lijuan Zhao,Chen Huang,Hanmin Wang,Garyfalia Drossopoulou

doi:10.1371/journal.pone.0108593

Abstract

BackgroundEpithelial-to-Mesenchymal Transition (EMT) induced by glucose in human peritoneal mesothelial cells (HPMCs) is a major cause of peritoneal membrane (PM) fibrosis and dysfunction.MethodsTo investigate serum response factor (SRF) impacts on EMT-derived fibrosis in PM, we isolated HPMCs from the effluents of patients with end-stage renal disease (ESRD) to analyze alterations during peritoneal dialysis (PD) and observe the response of PM to SRF in a rat model.ResultsOur results demonstrated the activation and translocation of SRF into the nuclei of HPMCs under extensive periods of PD. Accordingly, HPMCs lost their epithelial morphology with a decrease in E-cadherin expression and an increase in α-smooth muscle actin (α-SMA) expression, implying a transition in phenotype. PD with 4.25% glucose solution significantly induced SRF up-regulation and increased peritoneal thickness. In immortal HPMCs, high glucose (HG, 60 mmol/L) stimulated SRF overexpression in transformed fibroblastic HPMCs. SRF-siRNA preserved HPMC morphology, while transfection of SRF plasmid into HPMCs caused the opposite effects. Evidence from electrophoretic mobility shift, chromatin immunoprecipitation and reporter assays further supported that SRF transcriptionally regulated Snail, a potent inducer of EMT, by directly binding to its promoter.ConclusionsOur data suggested that activation of SRF/Snail pathway might contribute to the progressive PM fibrosis during PD.

Highlights

Peritoneal dialysis (PD) is currently used as a chronic, lifesustaining treatment by approximately 197,000 end-stage renal disease (ESRD) patients, or 11% of the global dialysis population [1]
Nuclear translocation of Serum response factor (SRF) occurs in human peritoneal mesothelial cells and morphological and biomarker alterations are consistent with Epithelial-to-Mesenchymal Transition (EMT) in continuous ambulatory peritoneal dialysis (CAPD) patients
To verify the phenotype of the human peritoneal mesothelial cells (HPMCs) from the PD effluents, we examined expression of E-cadherin, a typical epithelial marker, and a-smooth muscle actin (a-SMA), a typical mesothelial marker, by immunofluorescence

Summary

Introduction

Peritoneal dialysis (PD) is currently used as a chronic, lifesustaining treatment by approximately 197,000 end-stage renal disease (ESRD) patients, or 11% of the global dialysis population [1]. The epithelial-tomesenchymal transition (EMT) is a complex, step-wise phenomenon beneficial for normal wound healing [3] but detrimental in fibrogenic diseases [4], such as peritoneal fibrosis. Biomarkers for EMT have been identified and categorized, including the loss of the epithelial adhesion protein E-cadherin and upregulation of the mesenchymal marker a-smooth muscle actin (a-SMA) [5]. SRF plays important roles in diverse pathological processes, including EMT-derived tumor metastasis and fibrosis. SRF expression in hepatocellular carcinoma (HCC) cells that can undergo EMT may play an enhanced role in tumor progression [8]. Overexpression of SRF in colorectal carcinoma cells is associated with the modulation of E-cadherin/b-catenin expression and may enhance metastasis [9]. Epithelial-to-Mesenchymal Transition (EMT) induced by glucose in human peritoneal mesothelial cells (HPMCs) is a major cause of peritoneal membrane (PM) fibrosis and dysfunction

Methods

Results

Conclusion