Fig. 1.
Endothelial permeability is regulated by MLC phosphorylation and reorganization of the actin cytoskeleton and by tethering forces in the intercellular junctions of endothelial cells. Actin non-muscle–myosin interaction is regulated by myosin light chain (MLC) phosphorylation, which is controlled by Ca2+/calmodulin-dependent activation of MLC kinase (MLCK) and regulation of the MLC phosphatase activity. Both tight junctions (containing occludin, claudins, ZO-1, ZO-2 and ZO-3) and adherens junctions (V,E-cadherin connected via α- and β-catenins and plakoglobin connected to the actin cytoskeleton) contribute to junctional stability. (Adapted from van Hinsbergh, 1997.)