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

Abstract

BackgroundTumor necrosis factor (TNF)-α 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. MethodsExpression of LAYN was investigated in kidneys of mice administered with TNF-α and in a clear cell renal carcinoma cell line of KMRC-1 stimulated with TNF-α 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-α and transforming growth factor (TGF)-β in LAYN-knocked down KMRC-1 cells were investigated by qPCR and immunocytochemistry. ResultsAdministration of TNF-α increased expression of LAYN in renal tubular epithelia in mice. TNF-α but not TGF-β 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-α 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-β-induced EMT was not affected by the LAYN knockdown. ConclusionOur data indicate that LAYN is involved in the TNF-α-induced EMT of renal tubular epithelial cells. LAYN may play roles in the generation of renal interstitial fibrosis in GN via TNF-α-induced EMT.