Cell-to-cell-junctions of endothelial cells are specialized and differentia
ted areas of the plasma membrane. The main functions include the separation
of the intravascular and extravascular compartments, the mechanical connec
tion of the cells, and the maintenance of the cell polarity.
Although a wide heterogeneity of endothelial cell-to-cell junctions exists
in situ, they should be considered in general as adherens type junctions in
which gap and tight junctions are morphologically inserted.
Under certain pathological conditions, such as wound healing, angiogenesis
and many types of inflammation, the interendothelial junctions have to be d
issociated and reorganized in which proteins of the junctions are crucially
involved. These important mechanisms predict a sophisticated regulation of
junctional proteins. The present paper describes the organization and func
tional aspects of the occludin/ZO-1 complex typically found in tight juncti
ons, the cadherin/ catenin complex of the adherens junctions and the connec
tion of these protein complexes to the dense peripheral band via actin fila
ments. In addition, special attention has been drawn on the function of jun
ction-associated proteins with respect to their role under fluid shear stre
ss and interendothelial gap formation during inflammation.