Department of Orthopaedic Surgery, the First Affiliated Hospital, Chongqing Medical University, Chongqing, China.
BMB Rep. 2012 Sep;45(9):509-14. doi: 10.5483/bmbrep.2012.45.9.053.
We have found that the previously uncharacterized bone morphogenetic protein-9 (BMP9) is one of the most osteogenic factors. However, it is unclear if BMP9 cross-talks with TGFβ1 during osteogenic differentiation. Using the recombinant BMP9 adenovirus, we find that low concentration of rhTGFβ1 synergistically induces alkaline phosphatase activity in BMP9-transduced C3H10T1/2 cells and produces more pronounced matrix mineralization. However, higher concentrations of TGFβ1 inhibit BMP9-induced osteogenic activity. Real-time PCR and Western blotting indicate that BMP9 in combination with low dose of TGFβ1 potentiates the expression of later osteogenic markers osteopontin, osteocalcin and collagen type 1 (COL1a2), while higher concentrations of TGFβ1 decrease the expression of osteopontin and osteocalcin but not COL1a2. Cell cycle analysis reveals that TGFβ1 inhibits C3H10T1/2 proliferation in BMP9-induced osteogenesis and restricts the cells in G(0)/G(1) phase. Our findings strongly suggest that TGFβ1 may exert a biphasic effect on BMP9-induced osteogenic differentiation of mesenchymal stem cells.
我们发现先前未被表征的骨形态发生蛋白 9（BMP9）是最具成骨活性的因子之一。然而，BMP9 是否在成骨分化过程中与 TGFβ1 发生交叉对话尚不清楚。使用重组 BMP9 腺病毒，我们发现低浓度 rhTGFβ1 协同诱导 BMP9 转导的 C3H10T1/2 细胞中碱性磷酸酶活性，并产生更明显的基质矿化。然而，较高浓度的 TGFβ1 抑制 BMP9 诱导的成骨活性。实时 PCR 和 Western blot 表明，BMP9 与低剂量 TGFβ1 联合增强了后期成骨标志物骨桥蛋白、骨钙素和胶原类型 1（COL1a2）的表达，而较高浓度的 TGFβ1 则降低了骨桥蛋白和骨钙素的表达，但不降低 COL1a2 的表达。细胞周期分析表明，TGFβ1 抑制 BMP9 诱导的成骨分化过程中 C3H10T1/2 的增殖，并将细胞限制在 G0/G1 期。我们的研究结果强烈表明，TGFβ1 可能对间充质干细胞的 BMP9 诱导的成骨分化产生双相作用。
