Roles of layilin in TNF-α-induced epithelial-mesenchymal transformation of renal tubular epithelial cells

Background: Tumor necrosis factor (TNE)-alpha is suggested to induce epithelial-mesenchymal transformation (EMT) of renal tubular epithelial cells that possibly exacerbates renal interstitial fibrosis in glomerulonephritis (GN). We here investigated whether layilin (LAYN), a c-type lectin-homologous protein, was involved in the EMT process. Methods: Expression of LAYN was investigated in kidneys of mice administered with TNF-alpha and in a clear cell renal carcinoma cell line of KMRC-1 stimulated with TNF-alpha by quantitative polymerase chain reaction (qPCR) and/or western blotting. Expression of LAYN was assessed immunohistochemically in renal biopsy samples of patients with various types of GN. Changes of EMT markers and cell morphology by TNF-alpha and transforming growth factor (TGF)-beta in LAYN-knocked down KMRC-1 cells were investigated by qPCR and immunocytochemistry. Results: Administration of TNF-alpha increased expression of LAYN in renal tubular epithelia in mice. TNF-alpha but not TGF-beta increased expression of LAYN in KMRC-1 cells. Renal biopsy samples from the patients with GN showed high expression of LAYN in tubular epithelial cells. TNF-alpha induced up-regulation of vimentin, down-regulation of E-cadherin, and fibroblast-like morphological change in KMRC-1 cells, indicating occurrence of EMT. These changes were not observed in the LAYN-knocked down cells. In contrast, similarly occurred TGF-beta-induced EMT was not affected by the LAYN knockdown. Conclusion: Our data indicate that LAYN is involved in the TNF-alpha-induced EMT of renal tubular epithelial cells. LAYN may play roles in the generation of renal interstitial fibrosis in GN via TNF-alpha-induced EMT. (C) 2015 Elsevier Inc. All rights reserved.