Expression Change Of Signaling Molecule Related Wnt Signal Pathway In Mouse Cleft Palate Induced By Retinoic Acid During Perinatal Stage

Background: Retinoic acid-induced cleft palate in mice is a common and reliable animal model to probe the mechanism of congenital cleft palate which is caused by gene-environment interactions.?Retinoic acid realize its function though binding with its membrane receptor into intracellular. Then the retinoic acid binding protein transport it into the nucleus and combine the corresponding receptors, ultimately regulated gene transcription. Many Signaling pathways, such as Wnt, Shh and BMP, have been shown to participate in this process. The mechanism of Retinoic acid induced cleft palate is a direct impact on the neural crest cells migration and proliferation in the early development, and the defect phenotype is similar to which Wnt5a, Shh, BMP-4 and FGF-10 gene knockout result in cleft palate in mice.Objective: To verify the signaling molecules, GSK-3β, Fzd3 andβ-TrCP, which are screened from the palate tissue genome of the retinoic acid-induced cleft palate in mice by the Gene chip Technology completed by our group, are relating with Wnt signal pathway. Furthermore, observed the gene expression change in the normal palate and cleft palate during perinatal stage and explored the effects which due to retinoic acid induced cleft palate in newborn mice on the Wnt signaling pathway.Methods: Utilizing a single dose of 100mg/kg of RA to establish the mouse model of RA-induced cleft palate. Harvest the palate tissue from the control group and the RA group at E18 and PN0 respectively. To detect the expression and distribution of GSK-3β, Fzd3 andβ-TrCP at E18 and PN0 in control group and RA group by Real-time RT-PCR and immunohistochemistry.Results: 1. mRNA expression change of GSK-3β, Fzd3 andβ-TrCP at E18 and PN0 stage: GSK-3βand Fzd3 are expressed both at E18 and PN0 stages. The mRNA expression level of GSK-3βand Fzd3 at PN0 stage is higher than E18 stage. The RA groups are significant difference (P<0.05)in the GSK-3βand Fzd3, respectively. But, the WT groups are equivalency;β-TrCP is also expressed both at two stages. On the contrary, its expression in WT groups is significant (P<0.05), and there is no difference between RA groups (P >0.05).At the E18 stage, the mRNA expression in the WT group and the RA group of GSK-3βand Fzd3 is little change (P>0.05). The expression ofβ-TrCP in WT group and RA group at E18 stage is significant (P<0.05); Notably, expression level of GSK-3β, Fzd3 andβ-TrCP in the RA group is higher than the WT group at the PN0 stage, with a significant difference (P<0.05).2. Immunohistochemistry results of PN0 stage shows that: In the WT group, GSK-3β, Fzd3 andβ-TrCP are expressed in palatal epithelium cell, the expression of the oral side palatal epithelium cell is strong.β-TrCP shows weak expression in palatal mesenchyme, while GSK-3βand Fzd3 exhibit no expression. In the RA group, GSK-3β, Fzd3 andβ-TrCP are expressed strongly in oral side epithelium cell, particularly in MEE (medial edge epithelium) cell. At the same time, GSK-3β, Fzd3 andβ-TrCP are also expressed in the palatal mesenchyme.Conclusions: Consistent with the results show that gene expression up-regulation of GSK-3β, Fzd3 andβ-TrCP which are the inhibitors of the Wnt signaling pathway in the RA-induced cleft palate at PN0 stage, suggesting that Retinoic acid maybe through regulating above inhibitors to restrain the Wnt signaling pathway activation.