Epithelial–mesenchymal Transition of Glomerular Podocytes: Implications in Proteinuria

Abstract

The kidneys play an essential role in filtration of blood plasma, regulation of water, electrolyte, and acid/base balance of the body, and thus maintain overall homeostasis. The glomerular filtration barrier serves as a size, shape, and charge barrier to ensue glomerular permselectivity, so that kidneys excrete almost protein-free urine. Podocytes are glomerular visceral epithelial cells and significantly contribute to the glomerular permeability owing to their unique structure and specialized function. Nevertheless, podocytes are susceptible to various insults, including altered metabolites, aberrant signaling molecules , and mutations to critical proteins that otherwise ensue normal function. Podocyte injury is a predominant indicator of several glomerular diseases that are manifested by proteinuria. Epithelial-mesenchymal transition (EMT) is considered as one of the responses of podocytes to the noxious stimuli, which consequently results in podocyte depletion and proteinuria. This review discusses the importance of podocytes in normal renal filtration and details the molecular and cellular events that lead to EMT of podocytes vis-à-vis impaired glomerular filtration.