Overexpression of α-catenin increases osteoblastic differentiation in mouse mesenchymal C3H10T1/2 cells

α-and β-Catenin link cadherins to the actin-based cytoskeleton at adherens junctions and regulate cell-cell adhesion. Although roles of cadherins and canonical Wnt-/β-catenin-signaling in osteoblastic differentiation have been extensively studied, the role of α-catenin is not known. Murine embryonic mesenchymal stem cells, C3H10T1/2 cells, were transduced with retrovirus encoding α-catenin (MSCV-alpha-catenin-HA-GFP). In the presence of Wnt-3A conditioned medium or osteogenic medium (β-glycerol phosphate and ascorbic acid), cells overexpressing α-catenin showed enhanced osteoblastic differentiation as measured by alkaline phosphatase (ALP) staining and ALP activity assay compared to cells transduced with empty virus (MSCV-GFP). In addition, mRNA expression of osteocalcin and Runx2 was significantly increased compared to control. Cell aggregation assay revealed that α-catenin overexpression has significantly increased cell-cell aggregation. However, cellular β-catenin levels (total, cytoplasmic-nuclear ratio) and β-catenin-TCF/LEF transcriptional activity did not change by overexpression of α-catenin. Knock-down of α-catenin using siRNA decreased osteoblastic differentiation as measured by ALP assay. These results suggest that α-catenin overexpression increases osteoblastic differentiation by increasing cell-cell adhesion rather than Wnt-/β-catenin-signaling. (C) 2009 Elsevier Inc. All rights reserved.Lien WH, 2008, J CELL SCI, V121, P1357, DOI 10.1242/jcs.020537Cho SW, 2008, BIOCHEM BIOPH RES CO, V367, P399, DOI 10.1016/j.bbrc.2007.12.128YAVROPOULOU MP, 2007, HORM-INT J ENDOCRINO, V6, P279Mbalaviele G, 2006, J BONE MINER RES, V21, P1821, DOI 10.1359/JBMR.060811Lien WH, 2006, SCIENCE, V311, P1609, DOI 10.1126/science.1121449Drees F, 2005, CELL, V123, P903, DOI 10.1016/j.cell.2005.09.021Hwang SG, 2005, J BIOL CHEM, V280, P12758, DOI 10.1074/jbc.M413367200STAINS JP, 2005, BIRTH DEFECTS RES C, V75, P72Kobielak A, 2004, NAT REV MOL CELL BIO, V5, P614, DOI 10.1038/nrm1433Castro CHM, 2004, J CELL SCI, V117, P2853, DOI 10.1242/jcs.01133Nelson WJ, 2004, SCIENCE, V303, P1483MAGIE CR, 2002, DEVELOPMENT, V129, P1215Kawaguchi J, 2001, J BONE MINER RES, V16, P1265Lemonnier J, 2001, J BONE MINER RES, V16, P832Vasioukhin V, 2001, CELL, V104, P605, DOI 10.1016/S0092-8674(01)00246-XCheng SL, 2000, J BONE MINER RES, V15, P2362Hay E, 2000, J CELL PHYSIOL, V183, P117Giannini AL, 2000, EXP CELL RES, V255, P207Gumbiner BM, 2000, J CELL BIOL, V148, P399Ferrari SL, 2000, J BONE MINER RES, V15, P198Shin CS, 2000, J CELL BIOCHEM, V78, P566Gimond C, 1999, J CELL BIOL, V147, P1325Cheng SL, 1998, J BONE MINER RES, V13, P633Cadigan KM, 1997, GENE DEV, V11, P3286Sehgal RNM, 1997, J CELL BIOL, V139, P1033Torres M, 1997, P NATL ACAD SCI USA, V94, P901, DOI 10.1073/pnas.94.3.901Gumbiner BM, 1996, CELL, V84, P345RIMM DL, 1995, P NATL ACAD SCI USA, V92, P8813WATABE M, 1994, J CELL BIOL, V127, P247HERRENKNECHT K, 1991, P NATL ACAD SCI USA, V88, P9156NAGAFUCHI A, 1988, EMBO J, V7, P3679