Regulation of Paracellular Transport across Tight Junctions by the Actin Cytoskeleton

Abstract

The epithelial lining of luminal organs such as the gastrointestinal and respiratory tract forms a regulated, selectively permeable barrier between luminal contents and the underlying tissue compartments. Paracellular permeability across epithelial and endothelial cells is in large part regulated by an apical intercellular junction also referred to as the tight junction (TJ). The tight junction and its subjacent adherens junction (AJ) constitute the apical junctional complex (AJC). The AJC is composed of a multiprotein complex, which affiliates with the underlying apical perijunctional F-actin ring. Such AJC association with the perijunctional F-actin ring is vital for maintaining its structure and function in health. Stimuli such as nutrients, internal signaling molecules and cytokines influence the apical F-actin organization and also modulate the AJC structure and paracellular permeability. Here we review some of the key stimuli that influence F-actin organization, AJC structure and paracellular permeability.