N-cadherin mediated distribution of β-catenin alters MAP kinase and BMP-2 signaling on chondrogenesis-related gene expression

We have examined the effect of calcium-dependent adhesion, mediated by N-cadherin, on cell sign a I in g during chondrogenesis Of multipotential embryonic Mouse C3H10T1/2 cells. The activity of chondrogenic genes, type 11 collagen, aggrecan, and Sox9 were examined in monolayer (non-chondrogenic), and micromass (chondrogenic) cultures of parental C3H10T1/2 cells and altered C3H10T1/2 cell lines that express a dominant negative form of N-cadherin (Delta 390TI/2) or overexpress normal N-cadherin (MNCD2-T1/2). Our findings show that missexpression or inhibition of N-cacherin in C3H10T1/2 cells results in temporal and spatial changes in expression of the chondrogenic genes Sox9, aggrecan, and collagen type II. We have also analyzed activity of the serum response factor (SRF), a nuclear target of MAP kinase signaling implicated in chondrogenesis. In semi-confluent monolayer cultures 0-minimum cell-cell contact) of C3H10T1/2, MNCD2-T1/2, or Delta 390-T1/2 cells, there was no significant change in the pattern of MAP kinase or bone morphogenetic protein-2(BMP-2)regulation of SRF. However, in micromass cultures, the effect of MAP kinase and BMP-2 on SRF activity was proportional to the nuclear localization of beta-catenin, a Wnt stabilized cytoplasmic factor that can associate with lymphoid enhancer-binding factor (LEF) to serve as a transcription factor. Our findings suggest that the extent of adherens junction formation mediated by N-cacherin can modulate the potential Wnt-induced nuclear activity of beta-catenin. Published 2005 Wiley-Liss, Inc.(dagger)