Tight junctions (TJs) are dynamic and highly organized plasma membrane-boundstructures at the limit between the apical and the lateral plasma membrane of mostepithelial and endothelial cells. Although TJs have long been considered as staticstructures merely providing a barrier to the paracellular flux of solutes and ions (“barrier”)and aiding in the establishment of cellular polarity by restricting proteins andlipids to the apical or basolateral membrane (“fence”), it is now recognized that TJproteinsalso coordinate and transduce the signals impinging on and emanating fromthe apical plasma membrane, partly by shuttling to the cell nucleus. Consequently,TJ-proteins influence pivotal cellular processes such as morphogenesis, gene expression,cytoskeletal dynamics, and cell proliferation. In addition, protein membersof cell polarity complexes impact upon the structural and functional integrity of TJsand vice versa. An overview of the exceptional functional capacity of TJ proteins beyondmerely serving as structural components of cellular junctions will be given.
Dr. Andreas Traweger
Institute of Tendon & Bone Regeneration,
Paracelsus Medical University, Salzburg