Acidic Fibroblast Factor On Renal Tubular Epithelial Cells - Myofibroblasts In Turn The Differentiation Of Experimental Research

Objective: A great deal of evidence were found that renal tubular epithelial-myofibroblast transdifferentiation (EMT) during the development of tubulointerstitial fibrosis in rat remnant kidney. This study investigated the mechanisms that induce EMT and the significance of extracellular signal-regulated kinase (ERK) cascade in this course in vitro. Methods: The normal rat kidney tubular epithelial line (NRK) were cultured for six day on glass or collagen type I -coated plate in the presence or absence of recombinant acid fibroblast growth factor (aFGF). Transdifferentiation of tubular cell into myoflbroblast was assessed by electron microscopy and by expression of a -smooth muscle actin (a -SMA).~ cytokeratin~ fibronectin and E-cadherin. In the course of EMT, actived extracellular signal-regulated kinase (ERK) were measured by western blot assay. Result: NRK cell cultured on glass or collagen-coated plates showed a normal epithelial morphology. Yet cultured in 5Ong/ml aFGF on collagen-coated plates cause profound changes. This involved hypertrophy, a loss of apical-basal polarity and microvilli, with cells becoming elongated and invasive, and formation of a new front-end back-end polarity, and the appearance of actin microfilaments and dense bodies. These morphological changes were companied by phenotypic changes. Immunohistochemistry and western blot staining showed that the addition of aFGF to subconfluent cell culture cause a loss of the epithelial marker cytokeratin, E-cadherin and increased expression mesenchymal marker flbronectin yet do novo expression a -SMA. While to confluent cell culture lead to increase of cell proliferation. In particular, cells with a transformed morphology showed a flbroblast-like reorganization of actin fibers along the cell axis. There was a dose-dependent increase in the percentage of cells expressing a -SMA with increasing concentrations of aFGF, which was inhibited by the addition of a neutralizing anti-aFGF antibody. Compared with growth on glass, cell culture on collagen-coated plates showed a significance increase (P