Abstract: Objective: To study the expression characteristics of Wnt5a in cementum of the mice after birth and the effect of Wnt5a on the differentiation of cementoblasts in vitro,and to illuminate the mechanism of Wnt noncanonical signaling in regulating the tooth development. Methods: The postnatal Kunming mice at the days 0.5,4.5,12.5,18.5,24.5 and 30.5 after birth were selected and divided into various groups by different time points (n=3).The mice were sacrificed and the lower first molar and peridentium were prepared.Immunohistochemical staining was used to detect the expression characteristics of Wnt5a in tooth and peridentium of the mice.The OCCM30 cells were divided into control group and experiment group.200 μg·L^-1 recombinant Wnt5a protein were added in experiment group, and nothing was added in control group;the total RNA in the cells was exrracted.The relative expression levels of Ocn,Opn,Alp,Bsp,Wnt5a,and Runx-2 genes in the OCCM30 cells in two groups were detected by RT-PCR method. Results: At the day 0.5 after birth,the expression of Wnt5a in the lower first molar tooth germ was negative.At the day 4.5 after birth,the expression of Wnt5a in ameloblasts and odontoblasts were positive.At the day 16.5 after birth,the expression of Wnt5a in cementoblasts was positive.At the days 20.5-30.5 after birth,the expressions of Wnt5a in odontoblasts and periodontal ligament cells were positive.Compared with control group,the relative expression levels of Ocn and Alp gene in the OCCM30 cells in experiment group were decreased (P<0.05). Conclusion: The expression of Wnt5a is regular at different tooth developmental stages after birth.Wnt5a can reduce the expression of differentiated genes and play an important role in the growth of cementum.

Key words: tooth development, Wnt5a, cementoblasts, immunohistochemistry, cementum