Renal tubular epithelial-mesenchymal transition in kidney fibrosis

Epithelial-mesenchymal transition (EMT), a process by which differentiated epithelial cells undergo a phenotypic conversion that gives rise to the matrix-producing fibroblasts and myofibroblasts, is increasingly recognized as an integral part of tissue fibrogenesis after injury. However, the degree to which renal tubular epithelial EMT contributes to kidney fibrosis remains a matter of intense debate and is likely to be context-dependent. Renal tubular EMT is an adaptive response of epithelial cells to a hostile or changing microenvironment and is regulated by many factors. Several intrace-llular signal transduction pathways such as transforming growth factor-β (TGF-β)/Smad and Wnt/β-catenin signaling are essential in controlling the process of renal tubular epithelial EMT which are potential targets of antifibrotic therapy presently. This review highlights the current understanding of renal tubular epithelial EMT and its underlying mechanisms to stimulate further discussion on its role in the pathogenesis of renal interstitial fibrosis.