The Preliminary Study Of The Effect Of Osterix On The Process Of Osteoblast Differentiation From Mesenchymal Stem Cells

In current society, skeleton diseases have drawn more attention and have forced people to perform studies in bone field more deeply. The skeleton is a complicate and dynamic tissue. Many factors are involved in skeleton formation and function, such as transcription factors, signal pathways, and chromosome modifying complexes. Among them, Runx2 and Osterix play crucial roles in osteoblast differentiation, bone formation, and development. Osterix is targeted by Runx2 and acts downstream of Runx2. In this thesis, I preliminarily investigated the roles of Osterix in the pathway of osteoblastic differentiation from a mesenchymal stem cell line C3H10T1/2.Through ALP staining, von Kossa staining and RT-PCR, we found that overexpression of Osterix could facilitate the osteoblastic differentiation from mesenchymal stem cells. But the capability of Osterix in inducing osteoblastic differentiation was much weaker than that of Runx2. Although we added TSA in the cells overexpressing Osterix, there were no significant phenotypic changes through ALP staining and von Kossa staining. Then through RT-PCR analysis, we found that under TSA treatments, the gene expression of Bone sialoprotein(BSP) or Osteocalcin(OCN), which are the osteoblast specific markers, differentially changed in the cells overexpressing Runx2 on day 6 after osteoblast differentiation, whereas in the cells overexpressing Osterix, the gene expression of OCN did not changed apparently and the gene expression of BSP seemed to change in a way different from the phenomenon that observed in the cells overexpressing Runx2. Therefore, the histone deacetylating activity did not significantly influence the osteoblastic differentiation that was induced by Osterix. And such activity may play more important roles in influencing the osteoblast differentiation that was induced by Runx2.In summary, our results suggest that Osterix has some effect on the process of mesenchymal cell differentiation into osteoblast. Osterix may exert its function in inducing osteoblastic differentiation from mesenchymal stem cells to an extent weaker than that of Runx2. Our preliminary data further suggest that the histone deacetylating activity does not apparently influence the Osterix induced osteoblastic differentiation. We believe that further study on these issues is needed in the future.