Cell cycle regulator p130 and β-catenin form complex in mesenchymal stem cells

p130/E2f4 suppressor complex inhibits the transcription of multiple genes that regulate the cell cycle and induces cell cycle arrest at G0/G1. This is a requirement for the initiation of cell differentiation in many tissues. Here, we found that the activation of the Wnt/β-catenin signaling in mesenchymal stem cells (MSC) induced by their coculture with the A-549 cells line or by growth in medium containing Li+ ions resulted in the accumulation of active forms of p130, E2f4, and β-catenin not coupled with the inhibition of the cell cycle. The synchronization of the MSC cell cycle produced by thymidine and nocodazole did not change the level and phosphorylation pattern of p130. Unlike MSC mouse hepatocytes and T98G cells accumulated the p1 and p2 forms of p130 in the quiescent state and the p3 form during active proliferation. Antibodies to p130 precipitated β-catenin from extracts of MSC, while antibodies to β-catenin precipitated p130. The data obtained suggest that Gsk3β, p130, and β-catenin form a complex in MSC. The functional role of this complex may be associated with the activation of differentiation not coupled with cell cycle arrest. © 2011 Pleiades Publishing, Ltd.