Effect Of Ursolic Acid On Migration And Mineralization Of Osteoblastic Cell And Its Molecular Mechanism

The osteogenic osteocyte is a major cell in the process of orthodontic treatment and bone formation,and the equilibrium of this process is a precondition for tooth movement.Improper mechanical force or inflammation-induced bone formation may result in the resorption of orthodontic teeth.Promoting bone formation is a key issue in the orthodontic clinic.Ursolic acid(UA)is a natural pentacyclic triterpenoid found in plants in the Rosaceae family.UA has been shown to promote bone formation in osteogenic osteocytes and to regulate bone-forming protein expression.However,the molecular mechanism of UA is unclear.Thus,the role of UA in the migration and mineralization of osteogenic osteocytes and its molecular mechanism are explored,as follows:Firstly,the CCK-8 cell proliferation toxicity test was used to screen the concentration of UA,and the three concentrations of 1.25 μM,2.5 μM,and 5 μM were selected for the cell cycle.The results showed that UA had no significant effect on cell proliferation in a specific concentration range.However,cell scratch experiments proved that UA can promote the migration of osteoblasts.Secondly,the results of the Alkaline phosphatase(ALP)activity test indicated that the ALP expression was elevated in osteoblast differentiation.UA was used to study the effect of UA on bone formation in dental bone formation.The results indicated that UA significantly increased the formation of mineralized nodules in a dose-dependent manner.Colorimetric analysis showed that the UA-stimulated osteogenic cells produced more mineralized matrix than those without stimulation.The results of q RTPCR indicated that the m RNA levels of Runx-2,ALP,BSP,OCN,and OPG in osteoblast were significantly regulated.The results indicated that UA could promote osteogenic differentiation and the mineralization of osteoblastic cells.Finally,RNA sequencing analysis of the highly correlated Mitogen-activated protein kinase(MAPK)pathway to clarify whether or not it activates the MAPK pathway.We analyzed the phosphorylation levels of p38,extracellular signal-regulated kinase1/2(ERK1/2),and c-Jun N-terminal kinase(JNK).The results of Western Blot indicated that UA could activate p38,ERK1/2,and JNK,and UA promoted that MAPK signaling pathway could promote osteoblastic migration and mineralization.In summary,UA can promote the migration and mineralization of cells but does not have a significant influence on cell proliferation,which is achieved by activating the MAPK signaling pathway.Our findings provide a basis for understanding the role of UA in the promotion of bone by regulating MAPK signaling.It also offers some suggestions for UA therapy for root resorption caused by orthodontics.