Cell-Cell Interaction Mediated by Cadherin-11 Directly Regulates the Differentiation of Mesenchymal Cells Into the Cells of the Osteo-Lineage and the Chondro-Lineage

Abstract

We studied cadherin-11 function in the differentiation of mesenchymal cells. Teratomas harboring the cadherin-11 gene generated bone and cartilage preferentially. Cadherin-11 transfectants of C2C12 cells and cadherin-11 and/or N-cadherin transfectants of L cells showed that cadherin-11 together with N-cadherin-induced expression of ALP and FGF receptor 2. These results suggest that cadherin-11 directly regulates the differentiation of mesenchymal cells into the cells of the osteo-lineage and the chondro-lineage in a different manner from N-cadherin. Cell-cell interaction is an essential event for tissue formation; however, the role of cell-cell adhesion in mesenchymal tissue formation as well as in cell differentiation in this tissue remains unclear. cadherins, which are calcium-dependent cell adhesion receptors, form adherence junctions after adherence and aggregation of cells. Because cadherin-11 as well as N-cadherin has been reported to be a mesenchyme-related cadherin, we examined the cadherin-11 action in teratomas and in the cell lines C2C12 and L cell. Herein, we show that cell-cell interaction mediated by cadherin-11 is responsible for bone and cartilage formation. It has been previously reported that N-cadherin-expressing E-cadherin-/- ES transfectants formed neuroepithelium and cartilage in teratomas. Thus, we transfected the E-cadherin-/- ES cell line with the cadherin-11 gene. Moreover, we also transfected C2C12 cells and L cells with the cadherin-11 gene for morphological analysis and study of the induced differentiation at the molecular level. Teratomas derived from embryonic stem cells in which the cadherin-11 gene had been expressed exogenously contained bone and cartilage preferentially, showing that cadherin-11 is involved in mesenchymal tissue formation, specifically in controlling the differentiation of these cells into osteoblasts and chondrocytes. Therefore, we further examined the functional difference between cadherin-11 and N-cadherin. The expression patterns of cadherin-11 and N-cadherin in cells of the mouse osteoblastic cell line MC3T3-E1 showed that each cadherin was located independently of the cell-cell adhesion site and acted individually. In hanging drop cultures, cadherin-11 L cell transfectants aggregated in a sheet-like structure, whereas N-cadherin transfectants aggregated in a spherical form, indicating that each cadherin confers a different 3D architecture because of its individual adhesive property. To investigate the molecular mechanism of cadherin-11 action in cell differentiation, we analyzed cadherin-11 transfectants of C2C12 cells and cadherin-11 and/or N-cadherin transfectants of L cells and showed that cadherin-11, together with N-cadherin, induced expression of alkaline phosphatase (ALP) and fibroblast growth factor receptor 2. These results suggest that cadherin-11 directly regulates the differentiation of mesenchymal cells into the cells of the osteo-lineage and the chondro-lineage in a different manner from N-cadherin.