Identification of three human type-II classic cadherins and frequent heterophilic interactions between different subclasses of type-II classic cadherins

We identified three novel human type-II classic cadherins, cadherin-7, -9 a nd -10, by cDNA cloning and sequencing, and confirmed that they interact wi th catenins and function in cell-cell adhesion as do other classic cadherin s. Cell-cell binding activities of the eight human typo-Il classic cadherin s, including the three new molecules, were: evaluated by long-term cell-agg regation experiments using mouse L fibroblast clones transfected with the i ndividual cadherins. The experiments indicated that all the type-II cadheri ns appeared to possess similar binding strength, which was virtually equiva lent to that of E-cadherin. We next examined the binding specificities of t he type-II cadherins using the mixed cell-aggregation assay. Although all o f the type-II cadherins exhibited binding specificities distinct from that of E-cadherin, heterophilic interactions ranging from incomplete to complet e were frequently observed among them. The combinations of cadherin-6 and - 9, cadherin-7 and -14, cadherin-8 and -11, and cadherin-9 and -10 interacte d in a complete manner, and in particular cadherin-7 and -14, and cadherin- 8 and -11 showed an indistinguishable binding specificity against other cad herin subclasses, at least in this assay system. Although these data were o btained from an in vitro study, they should be useful for understanding cad herin-mediated mechanisms of development, morphogenesis and cell-cell inter actions in vitro.