Podocytes and Diabetic Nephropathy

The glomerular capillary wall comprises three major components: the fenestrated endothelium surrounded by glycocalyx, the glomerular basement membrane, and the podocyte layer. Podocytes are specialized epithelial cells that form a network of interdigitating foot processes. The predominant filtration pathway for macromolecules is through slit diaphragms bounded by podocyte foot processes. Nephrin is a key component of the slit diaphragm in association with other intracellular proteins, including CD2-associated protein (CD2AP), podocin, and α-actinin IV (Fig. 1). Together, these proteins contribute to the role of the slit diaphragm as the major size-selective filtration barrier.