A chimeric N-cadherin/beta 1-integrin receptor which localizes to both cell-cell and cell-matrix adhesions

To study the molecular mechanisms involved in formation of cell contacts, we have transfected cultured cells with a chimeric cDNA encoding the cytoplasmic and transmembrane domains of beta 1 integrin and the extracellular region of N-cadherin and determined the subcellular distribution of the chimeric molecule. We show that the chimeric receptor associates preferentially with cell-matrix focal contacts, suggesting that its distribution is directed by its beta 1 integrin segment, presumably via interactions of the cytoplasmic domain with cytoskeletal elements characteristic of focal contacts. Transfected cells which expressed relatively high levels of the cadherin/integrin chimera underwent an apparent epithelialization and contained the molecule both in cell-matrix and cell-cell contacts. Location in cell-cell contacts indicates competence of the cadherin extracellular domain to participate in formation of cell-cell junctions using a foreign cytoplasmic domain. Labeling of these cultures for talin, which is normally associated only with matrix adhesions, revealed specific labeling along the newly formed intercellular junctions. This suggests that the local association of talin with these sites is induced by the cytoplasmic tail of beta 1 integrin receptor presented by the chimeric protein. These results suggest that the formation of adherens-type junctions is driven by the cooperative interactions of the relevant adhesion molecules (cadherins and integrins) both with the respective extracellular ligands and with the cytoskeleton.