Expression Of PHEX And PHEX Antibody On Inhibtion Of Dentinogenesis Of PHEX During Tooth Germ Development In Mouse

Objective:To investigate spatio-temporal expression and effect of PHEX-antibody and possible roles of PHEX during tooth germ development in mouse, especially in the development of odontoblast.Methods1 To establish a model of tooth germ in mouse in the stages: early cap stage (E14), late cap stage (E16), early bell stage (E18), late bell stage (P1), the stage of dentin and enamel formation (P3, P5). Expression of PHEX protein was detected by method of immunohistochemistry in different developmental stages of tooth germ in mouse.2 According to the above expression of PHEX in different stages, the E17 mice received the injection with tail vein of the different concentrations of PHEX antibody(group A 0.1mg/kg, group B 0.5mg/kg, group N(control group) 0.5mg/kg0.1MPBS)to observe the subsequent development of the tooth germ. The hard tissues of tooth germ was observed by Mallory's trichrome stain, and expression of PHEX protein was detected by the method of immunohistochemistry. Results1 Spatio-temporal expression of PHEX protein during the tooth germ development: no positive staining of PHEX was found in early cap stage. In late cap stage PHEX was expressed weakly and sporadically in inner and outer enamel epithelium and dental sac. In early bell stage, PHEX mainly expressed in inner enamel epithelium and dental sac. Weak positive signals were also found in outer enamel epithelium, stratum intermedium and dental papilla cells adjacent to basement. In late bell stage PHEX which showed stronger positive expression gradually in ameloblasts and odontoblasts with the development of tooth germ. Positive PHEX expression was also detected in inner enamel epithelium at cervical loop, meanwhile it was negative in nearby dental papilla and outer enamel epithelium.2 To analyze the quantitative assessment of expression PHEX in the odontoblast : Significant difference of PHEX expression was not found in the location of odontoblast in E16 germ tooth(P>0.05), and was found in that of E18, P1, P3, P5(P<0.05)especially odotoblast of cusp's dentin. There is significant difference on stage of the germ tooth in the cylindrical cell, cube cell(P<0.05).3 Result of injecting anti-PHEX by the Mallory's trichrome stain: there was not different in development of the tooth germ in the E18. In the P1, P3, there was the odontoblast with the polarization and the dentinification in the group A and group N.The same thing was not shown in the group B. The inner enamel epithelium differentiated the ameloblast from enamel formation.4 Effect of expression PHEX with injecting anti-PHEX: In the E18, P1, P3, positive staining of PHEX was found in the inner enamel epithelium and the ameloblas, and a little in the outer enamel epithelium and dental sac with group A, group B, group N. In the P1, P2, it was found the ameloblast and the odontoblast with group A and group N, but was not find the odontsblast with group B.5 To analyze the quantitative assessment of expression PHEX in the odontoblast with injecting anti-PHEX: Significant difference of PHEX expression was not found in the odontoblast of E18. There was significant difference in the P1 and P3 with group A, group B and group N and spatio-temporal model with group A and group N, and we didn't find any difference in group B.ConclusionsSpatio-temporal expression of PHEX protein during the tooth germ development, expression of PHEX protein and dentinification was inhibited in the odontoblast with 0.5mg/kg PHEX antibody concentration.