The complexus adhaerens of mammalian lymphatic endothelia revisited: a junction even more complex than hitherto thought.
The significance of a special kind of VE-cadherin-based, desmoplakin- and plakoglobin-containing adhering junction, originally identified in certain endothelial cells of the mammalian lymphatic system (notably the retothelial cells of the lymph node sinus and a subtype of lining endothelial cells of peripheral lymphatic vessels), has been widely confirmed and its importance in the formation of blood and lymph vessels has been demonstrated in vivo and in vitro. We have recently extended the molecular and structural characterization of the complexus adhaerens and can now report that it represents a rare and special combination of components known from three other major types of cell junction. It comprises zonula adhaerens proteins (VE-cadherin, alpha- and beta-catenin, protein p120(ctn), and afadin), desmosomal plaque components (desmoplakin and plakoglobin), and tight-junction proteins (claudin-5 and ZO-1) and forms junctions that vary markedly in size and shape. The special character and the possible biological roles of the complexus adhaerens and its unique ensemble of molecules in angiogenesis, immunology, and oncology are discussed. The surprising finding of claudin-5 and protein ZO-1 in substructures of retothelial cell-cell bridges, i.e. structures that do not separate different tissues or cell layer compartments, suggests that such tight-junction molecules are involved in functions other than the "fence" and "barrier" roles of zonulae occludentes.
Hämmerling
Bettina
B
Division of Cell Biology, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120, Heidelberg, Germany.
Grund
Christine
C
Boda-Heggemann
Judit
J
Moll
Roland
R
Franke
Werner W
WW
D016475:3T3 Cells; D022005:Adherens Junctions / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D018938:Caco-2 Cells; D002417:Cattle; D002478:Cells, Cultured; D051180:Desmoplakins / Q000378:metabolism; D004729:Endothelium, Lymphatic / Q000648:ultrastructure*; D006801:Humans; D008198:Lymph Nodes / Q000648:ultrastructure; D042601:Lymphatic Vessels / Q000378:metabolism; D051379:Mice; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence
D051180:Desmoplakins