Alterations in Epithelial Polarity and the Pathogenesis of Disease States

Polarized epithelial cells transport ions, water, and macromolecules from one biologic compartment to another. These processes include absorption by enterocytes and renal tubular cells; secretion by hepatocytes, endocrine cells, and exocrine cells; and exchange by alveolar and capillary endothelial cells1,2. The performance of these functions depends on a surface membrane organized into structurally, biochemically, and physiologically distinct apical and basolateral domains containing different ion channels, transport proteins, enzymes, and lipids.The establishment and maintenance of these specialized surface-membrane domains is a multistage process. Alterations at any stage of this process could lead to cell dysfunction and ultimately a . . .