Glutamatergic Signaling Maintains the Epithelial Phenotype of Proximal Tubular Cells

Abstract

Epithelial-mesenchymal transition (EMT) contributes to the progression of renal tubulointerstitial fibrosis. The N-methyl-D-aspartate receptor (NMDAR), which is present in proximal tubular epithelium, is a glutamate receptor that acts as a calcium channel. Activation of NMDAR induces actin rearrangement in cells of the central nervous system, but whether it helps maintain the epithelial phenotype of the proximal tubule is unknown. Here, knockdown of NMDAR1 in a proximal tubule cell line (HK-2) induced changes in cell morphology, reduced E-cadherin expression, and increased ␣-SMA expression. Induction of EMT with TGF-␤1 led to downregulation of both E-cadherin and membrane-associated ␤-catenin, reorganization of F-actin, expression of mesenchymal markers de novo, upregulation of Snail1, and increased cell migration; co-treatment with NMDA attenuated all of these changes. Furthermore, NMDA reduced TGF-␤1-induced phosphorylation of Erk1/2 and Akt and the activation of Ras, suggesting that NMDA antagonizes TGF-␤1-induced EMT by inhibiting the Ras-MEK pathway. In the unilateral ureteral obstruction model, treatment with NMDA blunted obstruction-induced upregulation of ␣-SMA, FSP1, and collagen I and downregulation of E-cadherin. Taken together, these results suggest that NMDAR plays a critical role in preserving the normal epithelial phenotype and modulating tubular EMT.

VEGF ameliorates tubulointerstitial fibrosis in unilateral ureteral obstruction mice via inhibition of epithelial-mesenchymal transition

“…and increased motility [20][21][22] . To investigate the effect of VEGF on EMT in the kidney, α-SMA and E-cadherin protein and mRNA expression levels were determined by Western blot and RT-PCR, respectively, in UUO mice treated with or without VEGF.…”

Vascular Calcification Induced by Chronic Kidney Disease Is Mediated by an Increase of 1α-Hydroxylase Expression in Vascular Smooth Muscle Cells

“…Reverse transcription and real-time PCR were performed as described. (36) Briefly, real-time PCR with gene-specific TaqMan probes for rat and mouse VDR, 1a-hydroxylase, 24-hydroxylase, RUNX2, and GAPDH as an endogenous control (Applied Biosystems, Foster City, CA, USA) was performed with an ABI Prism 7000 Sequence Detection System (Applied Biosystems) using TaqMan Universal PCR Master Mix. Forty cycles at 95°C for 15 sec and 60°C for 1 min were performed.…”

Potential nephroprotective effects of the Chinese herbAngelica sinensisagainst cisplatin tubulotoxicity

“…When RPTECs are injured, these intercellular links are disrupted and b-catenin relocalizes into the nucleus after structural reconfiguration (Gottardi & Gumbiner, 2004). It then associates with the TCF/LEF complex and rules the transcription of several genes, notably those involved in fibrosis (Bozic et al, 2011). Research has suggested that inhibiting the b-catenin pathway restrains the progression of renal fibrosis (Hao et al, 2011;He et al, 2011).…”