Expression of osterix inhibits bone morphogenetic protein-induced chondrogenic differentiation of mesenchymal progenitor cells
Expression of osterix inhibits bone morphogenetic protein-induced chondrogenic differentiation of mesenchymal progenitor cells
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DOI：
10.1007/s00774-008-0003-0
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Imamura, Takeshi
中科院分区：
文献类型：
--
作者：
Tominaga, Hiroyuki;Maeda, Shingo;Imamura, Takeshi
成骨细胞和软骨细胞来源于普通的双能间充质祖细胞。虽然这两种细胞系的分化可以通过用骨形态发生蛋白（BMP）处理来诱导，但是间充质祖细胞对BMP的反应在细胞系与细胞系之间不同。在这里，我们证明，C3 H/10 T1/2细胞首选软骨分化，原代骨髓基质细胞（MSC）倾向于转化成骨细胞，ST-2细胞分化成骨细胞和软骨细胞谱系同时，这表明分子开关功能选择细胞的命运。Osterix是成骨细胞生成的二级主调节因子，BMP分别在MSC和ST-2细胞中以高水平和低水平诱导;相比之下，C3 H/10 T1/2细胞仅表现出微弱的表达。由于osterix被认为是软骨形成的负调节剂，我们假设C3 H/10 T1/2细胞的强烈软骨细胞分化可能是由于缺乏osterix。因此，我们使用腺病毒载体恢复osterix基因在C3 H/10 T1/2细胞中的表达。BMP处理后，感染osterix编码病毒显着抑制C3 H/10 T1/2细胞的软骨细胞分化，而不是导致突出的成骨细胞分化。这些结果表明，C3 H/10 T1/2细胞的软骨形成潜力被osterix表达废除。然而，使用慢病毒介导的shRNA沉默osterix基因并不能增强MSC的软骨细胞分化，尽管成功地抑制了成骨细胞分化。这些结果表明，低水平的osterix表达敲低后剩余的是足以阻止软骨形成，而更高的表达可能需要促进成骨细胞分化。
Osteoblasts and chondrocytes arise from common bipotential mesenchymal progenitor cells. Although the differentiation of these two cell lineages can be induced by treatment with bone morphogenetic proteins (BMPs), the responses of mesenchymal progenitors to BMP differ from cell line to cell line. Here we demonstrate that C3H/10T1/2 cells preferred chondrogenic differentiation, primary bone marrow stroma cells (MSCs) tended to convert to osteoblasts, and ST-2 cells differentiated into both the osteoblastic and chondrocytic lineages simultaneously, suggesting that a molecular switch functions to select cell fate. Osterix, the secondary master regulator of osteoblastogenesis, was induced by BMP at high and low levels in MSCs and ST-2 cells, respectively; in contrast, C3H/10T1/2 cells demonstrated only faint expression. As osterix has been suggested as a negative regulator of chondrogenesis, we hypothesized that the intense chondrocyte differentiation of C3H/10T1/2 cells may have resulted from an absence of osterix. We therefore restored osterix gene expression in C3H/10T1/2 cells using an adenovirus vector. Following BMP treatment, infection with an osterix-encoding virus dramatically inhibited the chondrocytic differentiation of C3H/10T1/2 cells, resulting instead in prominent osteoblast differentiation. These results indicate the chondrogenic potential of C3H/10T1/2 cells was abrogated by osterix expression. Chondrocyte differentiation of MSCs, however, was not enhanced by silencing the osterix gene using lentivirus-mediated shRNA, despite successful suppression of osteoblast differentiation. These results suggest that the low levels of osterix expression remaining after knockdown are sufficient to block chondrogenesis, whereas higher expression may be required to promote osteoblastic differentiation.