Shaping an epithelial cell: the role of cell adhesion molecules in the reorganization of the membrane cytoskeleton

Abstract

The generation of order from seeming chaos in biological systems is a central problem in developmental biology. A striking example of this is found in the formation of a polarized epithelium from unpolarized precursors during development. Polarized epithelia have a high degree of order at their cell surface that is characterized by the segregation of proteins into structurally and functionally distinct apical and basal—lateral membrane domains (Figure 2.1). The apical domain, which faces the topological outside of the organism, is specialized for protection, secretion, and the regulation of nutrient and fluid uptake. The basal—lateral domain is apposed to the circulatory system and is involved in communication with other parts of the body; hormone receptors and the machinery of the signal transduction pathway are located in this domain. Other proteins such as Na+,K+-ATPase, which are involved in the generation of ionic gradients, are also localized to the basal—lateral domain.