Translational Nephrology Podocyte actin in health, disease and treatment*

Brief review of the field Focal segmental glomerulosclerosis (FSGS) is a common and important cause of nephrotic syndrome. It is now gen-erally accepted that the predominant glomerular lesion in FSGS is injury to podocytes (visceral glomerular epithelial cells). Podocytes have a complex cellular architecture with interdigitating processes maintained by a precise organiza-tion of actin filaments in the cellular cytoplasm. Electron microscopic analysis of the glomerular capillary wall shows that, on the urinary side, the foot processes of the podocytes are organized in a precise manner with slits be-tween them through which filtration occurs (Figure 1A). It has been known for decades that a cardinal feature of the glomerular capillary wall in proteinuric states is flattening or effacement of the foot processes so that this precise or