In vivo functions of catenins.
The adhesion of cells to neighbor cells determines cellular and tissue morphogenesis and regulates major cellular processes including motility, growth, survival, and differentiation. Regions of cell-cell adhesion are adherens junctions, desmosomes, and tight junctions. Cadherins are transmembrane molecules whose extracellular domains transmit the direct interaction of two cells. The intracellular cadherin domains bind directly or indirectly to the submembranous catenins, which are linked to the cytoskeleton. Four types of catenins, alpha-catenin, beta-catenin, gamma-catenin, and p120 catenin are known. Three of them, beta-, gamma-, and p120 catenin, are structurally related and possess similar protein interaction domains, the so-called armadillo repeats. These catenins are also parts of signal transduction pathways and play a role in phenotypical changes of cells, e.g., during switches from adherent to migratory cells. The function of catenins in such basic cellular processes also determines a role of catenins in embryogenesis, adult tissue homeostasis, and disease. In particular, beta-catenin is known to be an important oncoprotein in human cancer development.
Brabletz
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Institute of Pathology, University of Erlangen-Nürrnberg, Krankenhausstr. 8-10, 91054, Erlangen, Germany, thomas.brabletz@patho.imed.uni-erlangen.de.