Effect Of Protein Arginine Methyltransferase 5 In Osteoblasts During Tooth Extraction Socket Healing

Objective:In order to explore the effect of Prmt5 on the healing of extraction sockets in mice,we established the model of extraction sockets in osteoblast specific Prmt5 knockout mice,and provided clues for promoting the healing of extraction sockets in clinic.Methods:1.Detect the expression of PRMT5 in the process of tooth extraction socket healing : C57BL/6 mice aged 6-8 weeks were selected for maxillary first molar extraction.The samples were collected on the 3rd,7th,10 th,14th,21 st,28th and 35 th day after tooth extraction,and the expression of PRMT5 was detected by Western Blot.2.Construct the conditional gene knockout mouse model.Prmt5fl/fl(control group)was hybridized with OC-Cre transgenic mice to obtain OC-Cre;Prmt5fl/fl mice(experimental group),and genotypes were identified.3.The maxillary first molars of control group and OC-Cre;Prmt5fl/fl mice were extracted at the age of 6-8 weeks to established the extraction fossa model.The samples were taken at 3 days,7 days,10 days,14 days,21 days,28 days and 35 days after tooth extraction.The body weight of the mice is weighed and Brdu(concentration 10mg/ml)is injected intraperitoneally at a dose of 10 ml / kg three hours before the mice are killed.The extraction fossa was scanned by Micro-CT,and the general phenotype of the extraction fossa was analyzed by imaging.The bone formation of tooth extraction fossa was histologically analyzed by paraffin section and Masson staining.The proliferation,differentiation and apoptosis of bone formation cells at 3 days,7 days and 14 days after tooth extraction were detected by immunofluorescence staining,and cytological analysis was carried out.Results:1.The results of western blot detection showed that the expression of PRMT5 increased gradually from 1 to 14 days after extraction,and then gradually returned to the level before extraction,suggesting that Prmt5 may play a role in the early stage of healing.2.The body size of OC-Cre;Prmt5fl/fl mice is smaller than that of control group,but the difference is not significant.3.Compared with control group,the healing of tooth extraction fossa in OC-Cre;Prmt5fl/fl mice was delayed.Micro-CT analysis showed that the healing of extraction fossa of Prmt5 knockout mice was delayed,the bone mineral density of new bone was lower and the structure of bone trabecula was sparse than that of control mice at the same time.Through further analysis of bone analysis parameters after 3D reconstruction,it was found that there were significant differences in bone volume fraction(BV/TV),bone mineral density(BMD),trabecular number(Tb.N),trabecular thickness(Tb.Th),trabecular separation(Tb.Sp)and trabecular pattern factor(TBPf)from 0 to 14 days after tooth extraction.The result of Masson staining was consistent with that of Micro-CT.The height of alveolar ridge,the number and thickness of bone trabeculae in control group mice were significantly higher than those in Prmt5 knockout mice.Therefore,3 days,7 days and 14 days were selected for cytological analysis.Immunohistochemical detection of osteoblast markers N-cadherin and Sp7,shows that the number of osteoblasts decreases in Prmt5 knockout mice.Then,through the cell proliferation test of Brdu method,it was found that the cell proliferation of Prmt5 knockout mice was higher than the control group.Through the detection of apoptosis,it is found that the apoptosis of Prmt5 knockout mice was higher than that of the control group.Conclusion:PRMT5 in osteoblasts may participate in the healing of tooth extraction fossa by promoting osteoblast differentiation and reducing apoptosis.