Podocyte

Podocytes (or visceral epithelial cells) are cells in the Bowman's capsule in the kidneys that wrap around capillaries of the glomerulus. The Bowman's capsule filters blood, retaining large molecules such as proteins while smaller molecules such as water, salts, and sugar are filtered as the first step in forming urine.

The long processes, or foot projections (pedicels) of the podocytes wrap around the capillaries, and leave slits between them. Blood is filtered through these slits, each known as a filtration slit or slit diaphragm. Several proteins are required for the foot projections to wrap around the capillaries and function. When infants are born with certain defects in these proteins, such as nephrin and CD2AP, their kidneys cannot function. People have variations in these proteins, and some variations may predispose them to kidney failure later in life. Nephrin is a zipper-like protein that forms the slit diaphragm, with spaces between the teeth of the zipper, big enough to allow sugar and water through, but too small to allow proteins through. Nephrin defects are responsible for congenital kidney failure. CD2AP regulates the podocyte cytoskeleton and stabilizes the slit diaphragm.