| Transcription factors can control the transcription of their target genes when they bind to the DNA-binding sites on their promotors. They can transfer the messages of growth factors and so on to those effective molecules. Nuclear transcriptor activator protein-1(AP-1) is a transcription . factor of this kind. Some researchers, both at home and abroad, have found recently that AP-1 is expressed during tooth development and that there are AP-1 binding sites on the promotor of DSPP, Am and DMP1 genes which are expressed in tooth development.Since the most typical complex of AP-1 is formed by c-fos and c-jun, we aimed at exploring the effect of c-fos and c-jun on teeth germ development and mineraliztion by cell culture in vitro, Western-blot, immunohistochemistry, etc. In orderto gain an insight into the molecular mechanisms of odontoblast differentiation and dentinogenesis and to give more groundwork for further research, the author sought to characterize the roles of c-fos and c-jun in BMP2 and TGF-B1 signaling, investigate the modulation of c-fos and c-jun expression by BMP2 and TGF-B1 in cultured human dental papilla cells in this study. The main content and results of the study are presented as follows.1. The expression of c-fos and c-jun during rat and mice tooth developmentThe expression of c-fos and c-jun was observed on different stages during rat and mice tooth development with immunohisto-chemical technique. Results: The temporal and spatial pattern of c-fos and c-jun expression during rat tooth development was similar to that of mice. There was a little difference between the expression of c-fos and c-jun, however, c-fos was found negative during the bud stage, but stained positive in dental epithelium during the cap stage, especially in the inner enamel epithelia. There was no c-jun protein during the bud and cup stages. During the bell stage, c-fos and c-jun was mainly detected in the pre- and functional odontoblasts and ameloblasts. Furthermore c-fos and c-jun had decreasing intensity with the mineralization, c-fos and c-jun were also expressed weakly in dental papilla and stellate reticulum. The stratum intermedium was strongly positive for c-fos and c-jun. In a word, the expression of c-fos and c-jun showed a decreasing intensity with the maturation of tooth germs.2. The expression of c-fos and c-jun during human tooth developmentThe expression of c-fos and c-jun on different stages of human tooth development was observed with immunohischeraical method. The results of the experiment indicated the time diathesis of the above expression, which was similar to that of rat and mice tooth development. During human tooth development, the expression of c-fos and c-jun appeared later than that during rat and mice tooth development. There were no postive signals in the enamel organ before bell stage. During the bell stage, c-fos and c-jun was negative in the pre-odontoblasts and pre-ameloblasts. The intensity of c-fos and c-jun increased in odontoblasts and ameloblasts when matrix was initially secreted. Furthermore most of the c-fos and c-jun positive cells were on the posterior sides of enamel organ. These results suggested that c-fos and c-jun could play an important role during the differentiation of odontoblasts, ameloblasts, dentin matrix secretion and mineralization3. The translocation of c-fos and c-jun in the human dental papilla cells treated by BMP2 and TGF-B1The effects of BMP2 and TGF-B1 were observed half-rationally with immunohistochemical technique and image analysis. Human dental papilla cells were treated with BMP2 or TGF-B1 at different time points. The human dental papilla cells of passage 5 were selected and grouped into experimental and control groups for this experiment. The result of the study demonstrated that the cytoplasm of the cells in the control group was found with negative signals, but there were slightly positive signals in the nucleus of these cells. Positive signals were found in both the nucleus and cytoplasm when treated with 200ng/ml BMP2 or 5ng/ml TGF-B1...
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