Identification of a novel cadherin (vascular endothelial cadherin-2) located at intercellular junctions in endothelial cells

Abstract

Endothelial cells express two major cadherins, VE- and N-cadherins, but only the former consistently participates in adherens junction organization. In heart microvascular endothelial cells, we identified a new member of the cadherin superfamily using polymerase chain reaction. The entire putative coding sequence was determined. Similarly to protocadherins, while the extracellular domain presented homology with other members of the cadherin superfamily, the intracellular region was unrelated either to cadherins or to any other known protein. We propose for this new protein the name of vascular endothelial cadherin-2. By Northern blot analysis, the mRNA was present only in cultured endothelial cell lines but not in other cell types such as NIH 3T3, Chinese hamster ovary, or L cells. In addition, mRNA was particularly abundant in highly vascularized organs such as lung or kidney. In endothelial cells and transfectants, this cadherin was unable to bind catenins and presented a weak association with the cytoskeleton. This new molecule shares some functional properties with VE-cadherin and other members of the cadherin family. In Chinese hamster ovary transfectants it promoted homotypic Ca2+ dependent aggregation and adhesion and clustered at intercellular junctions. However, in contrast to VE-cadherin, it did not modify paracellular permeability, cell migration, and density-dependent cell growth. These observations suggest that different cadherins may promote homophilic cell-to-cell adhesion but that the functional consequences of this interaction depend on their binding to specific intracellular signaling/cytoskeletal proteins.