The Role Of The Canonical Wnt Signaling In The Cementoblasts By Mechanical Stress In Vitro

Background and objective: Orthodontic tooth movement is achieved byremodeling of periodontal tissue triggered by orthodontic force． Theremodeling of periodontal tissue includes remodeling of alveolarbone、 periodontal ligament and Cementum. Cementob|ast plays a centralrole in repair root resorption. The canonical wnt signaling can promote theodontogenic differentiation in osteoblast. However,it is not known howorthodontic force influences the function of cementoblast and what is therelationship between the canonical wnt signaling and Runx2ofcementoblast.In this study,we cultured Cementoblasts OCCM30to explore therelationship between the canonical wnt signaling and Runx2by mechanicalstress.The experiment is divided into two parts:PartI:The expression of Runx2mRNA in Cementoblasts by mechanicalstress in vitro Methods: Cementoblasts OCCM30subjected to mechanical strain byFX4000T system with tension stress for0h,3h,6h,12h, then Runx2mRNAwas observed by real-time quantitative PCR. Results: PCR showed that theRunx2mRNA level was significantly up after loading mechanical stress.Conclusion: The mechanical stress can up the expression of Runx2mRNA incementoblasts in vitro.PartII:The activity of the canonical wnt signaling pathway in thecementoblasts by mechanical stressMethods: Cementoblasts OCCM30subjected to mechanical strain byFX4000T system with tension stress for0h,3h,6h,12h, then Western blot wasdone to detect theβ-catenin levels. Results: Western blot showed that theβ-catenin level was significantly up after loading mechanical stress.Conclusion: The mechanical stress can activate the canonical Wnt signalingpathway in cementoblasts in vitro.PartIII:The role of the canonical wnt signaling in the expression ofRunx2mRNA in Cementoblasts in vitroMethods: Cementoblasts OCCM30were pretreated by Dkk1for48h,the concentration of DKK1separately are0ng/ml,20ng/ml,50ng/ml80ng/ml,100ng/ml,150ng/ml,then Western blot was done to detect theβ-cateninlevels in nucleus;and Runx2mRNA was observed by real-timequantitative PCR. Results: Western blot showed that the β-catenin level wassignificantly down by DKK1,with it, the Runx2mRNA level was also significantly down. Conclusion: the canonical wnt signaling pathway can upthe expression of Runx2mRNA in Cementoblasts.PartIV:The role of the canonical wnt signaling in the expression ofRunx2mRNA in Cementoblasts by mechanical stress in vitroMethods: Cementoblasts OCCM30were pretreated by150ng/ml Dkk1for48h,and then subjected to mechanical strain by FX4000T system withtension stress for12h.Western blot was done to detect the β-cateninlevels innucleus;and Runx2mRNA was observed by real-time quantitative PCR.Results: Western blot showed that the β-catenin level was significantly downby DKK1,and up by mechanical stress,with it, the Runx2mRNA level havethe same change. Conclusion: the canonical wnt signaling pathway can upthe expression of Runx2mRNA in Cementoblasts.