Endothelial adherens junctions at a glance.

Adherens junctions have an important role in the control of vascular permeability. These structures are located at cell-to-cell contacts, mediate cell adhesion and transfer intracellular signals. Adhesion is mediated by cadherins, which interact homophilically in trans and form lateral interactions in cis. VE-cadherin (also known as CDH5 and CD144) is the major component of endothelial adherens junctions and is specific to endothelial cells. Endothelial cells from different types of vessels, such as lymphatic vessels, arteries and veins, show differences in junction composition and organization. Vascular permeability is increased by modifications in the expression and function of adherens junction components. In some cases these defects might be cause of pathology. In this Cell Science at a Glance article, we present the example of the so-called cerebral cavernous malformation (CCM), where adherens junctions are dismantled in the vessels contributing to brain microcirculation. This causes the loss of endothelial cell apical-basal polarity and the formation of cavernomas, which are fragile and hemorrhagic. Other diseases are accompanied by persistent alterations of vascular morphology and permeability, such as seen in tumors. It will be important to achieve a better understanding of the relationship between vascular fragility, malformations and junctional integrity in order to develop more effective therapies.