Cell-cell junctions play crucial roles in the organization and function of epithelial and endothelial cellular sheets. Here, we have identified the protein product for KIAA1462 gene, whose single nucleotide polymorphisms (SNPs) have recently reported to be associated with coronary artery disease, as a novel component of cell-cell junctions. We propose the name of KIAA1462 protein junctional protein associated with coronary artery disease (JCAD). JCAD is a ∼145 kDa protein without any known domains but contains a proline-rich region. Immunolocalization studies revealed that JCAD is specifically localized at cell-cell junctions in endothelial cells but not in epithelial cells. The accumulation of JCAD at cell-cell junctions in cultured endothelial cells was impaired by RNAi-mediated suppression of VE-cadherin expression. In cell adhesion-deficient mouse L fibroblasts, JCAD was recruited to cell-cell contacts when cadherin-mediated cell-cell adhesion was induced. These results indicate that JCAD is a component of VE-cadherin-based cell-cell junctions in endothelial cells. This study also suggests the implication of endothelial cell-cell adhesion in coronary artery disease.
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