| Extracellular matrix (ECM) is a highly organized network composed of macromolecules, which mainly consists of collagen, non-collagenous proteins, elastin, proteoglycan, et al. ECM is the suitable environment for the normal cells to maintain their existent activities and differentiation, the timely breakdown of which is essential for embryoid development, morphogenesis, reproduction, and tissue resorption and remodeling. Matrix metalloproteinases (MMPs), one of the key factors, change the bio-function of ECM macromolecular substance through albumen hydrolysis, and sequentially, take part in the degradation of ECM during the process of organization absorbability and sick period. The tissue inhibitor of metalloproteinases (TLMPs), which is major endogenous regulators of MMP activiesin, play an important role in the matrix synthesis and degradation balance.Amelogenin, the key component of enamel matrix , can be degraded by re-combined enamelysin (MMP-20), the newcomer of MMPs family. The aim of this study is to explicit the expression of MMP-20, TIMP-1 and TIMP-2 in the development of tooth, as well as in the normal and inflamed dental pulp .And tostudy the influence of LPS and BMP2 on the expression of MMP-20, TIMP-1 and TIMP-2 in human dental pulp fibroblast in vitro. The main content and results of the study are presented as following.1.The expression of MMP-20 mRNA and TIMP-1, TEMP-2 mRNA during rat tooth developmentThe expression of MMP-20 mRNA and TIMP-1, TIMP-2 mRNA were observed on different stages during rat teeth development by in situ hybridization. Result: During cap stage and early bell stage, the expression of MMP-20 mRNA was negative in enamel organ, dental papilla and dental sac and that of TIMP-1 mRNA could be observed in dental papilla; there was the expression of TIMP-2 mRNA in dental papilla and no expression in enamel organ. During late bell stage, the positive expression of MMP-20 mRNA in ameloblasts and odontoblasts could be seen as well as that of TIMP-1 mRNA in odontoblasts and that of TEMP-2mRNA in odontoblasts and dental papilla. The above results indicate that the expressions of MMP-20 and TIMP-1, TIMP-2 have time and cell differential diathesis, which coordinate in the formation of teeth hard tissue with each other2.The expression of MMP-20 mRNA and TIMP-1, TIMP-2 mRNA during human tooth developmentTo study the expression of MMP-20 mRNA and TIMP-1, TIMP-2 protein during human tooth development and to obtain the development and mineralization mechanism of human tooth, the expression of MMP-20 mRNA and TEMP-1, TIMP-2 on different stages of human tooth development was observed by in situ hybridization and immunohistochemical staining. The results of the experiment indicate the time differential diathesis of the above expression, which is as the sameas that during rat tooth development. MMP-20 mRNA did not appear in ameloblasts and odontoblasts until the late bell stage, which suggests that it is similar that the tooth development of different kinds of life-forms and MMP-20 plays a role in the formation of human tooth hard tissue as well. It does great help in understanding the mechanism of the injury repair of pulp to further study the function of MMP-20 in the formation of reparative dentin.S.Comparative study of MMP-20 mRNA and TIMP-I, TIMP-2 in healthy and inflamed dental pulp of humanThe expressions of MMP-20 mRNA and TIMP-1, TIMP-2 protein in normal and inflamed pulp were observed by in situ hybridization and immunohisto-chemistry. There are no expression of MMP-20 mRNA, positive expression of TIMP-1 and TIMP-2 in odontoblasts and fibroblasts of both normal and inflamed pulp. The results show that there is TIMP-1 and TEMP-2 expression in either normal and inflamed pulp, pulp fibroblast is the key cell for producing TIMP-1 and TIMP-2 in pulp tissue, TIMP-1 and TIMP-2 will react to pulp inflammation and MMP-20 takes no part in the degradation of ECM during inflammation.4.The influence of LPS on the expression of MMP-20 mRNA and TIMP-1, TIMP-2 in H... |
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