Investigation of relationship between Osterix and Cbfal during BMP2-induced osteoblast differentiation

1. Osterix在成骨细胞分化中的作用我们发现过表达Osterix可促进间充质细胞向成骨细胞分化。微阵列分析表明，Osterix与Cbfa1具有共同和不同的靶基因。因此，我们的研究结果表明Osterix不仅作为Cbfa 1的下游功能，而且还独立于Cbfa 1调节成骨细胞的发生。2.不依赖于Cbfa 1的Osterix表达的调节我们证明了BMP 2在Cbfa 1缺陷的间充质细胞中诱导Osterix表达。Osterix在细胞中的诱导作用是由Smad信号和同源盒基因介导的。3. Osterix的靶基因为了确定Osterix的靶基因，我们进行了微阵列分析，发现一个含有RRM基序的转录调控蛋白参与成骨细胞分化。4. Osterix和Cbfa 1在Ihh介导的成骨细胞分化中的作用为了了解Ihh刺激成骨细胞分化的分子基础，我们研究了Osterix和Cbfa 1在这一过程中的作用。我们发现，Gli2，激活Ihh，调节Runx2的表达和功能，但不是Osterix。这些结果表明，Gli2通过控制Cbfa1促进成骨细胞分化。

1.Role of Osterix in osteoblast differentiationWe found that overexpression of Osterix promoted differentiation of mesenchymal cells into osteoblasts. Microarray analysis indicated that Osterix has common and distinct target genes from Cbfa1. Therefore, our findings suggest that Osterix not only functions as a downstream of Cbfa1 but also regulates osteoblastogenesis independently of Cbfa1.2.Cbfa1-indepenednt regulation of Osterix expressionWe demonstrated that BMP2 induced Osterix expression in Cbfa1 deficient mesenchymal cells. Induction of Osterix in the cells was mediated by Smad signaling and homeobox gene.3.Target genes of OsterixTo identify the target genes of Osterix, we performed microarray analysis and found that a transcriptional regulatory protein containing RRM motif is involved in osteoblast differentiation.4.Role of Osterix and Cbfa1 in Ihh-mediated osteoblast differentiationTo understand the molecular basis by which Ihh stimulates osteoblast differentiation, we investigate the role of Osterix and Cbfa1 in this process. We found that Gli2, activated by Ihh, regulated expression and function of Runx2 but not those of Osterix. These results indicate that Gli2 promotes osteoblast differentiation by controlling Cbfa1.