The Study Of Bufo Raddei Pax6Variant In Rat Corneal Epithelium Cells

Paired box6variant (VP) specifically found in Bufo raddei is a member of Paired box6(Pax6) gene family. In compare with typical Pax6protein, VP has the complete paired domain and paired-type homeodomain. However, the predicted protein pHospHorylation sites and protein kinase recognition sites in PST region at the C terminal of the VP are significantly different from Pax6protein. Since the PST region plays a role in the transactivation properties, we focused on the biological function of VP. Altered expression of both VP and Pax6were observed during stage12-25of Bufo raddei embryonic development. In order to explore the possible function of VP, we overexpressed VP and Pax6in rat corneal epithelial cells. Immunofluorescence staining shows that VP is located in the cell nucleus just as Pax6. Overexpression of VP inhibits cell proliferation by inhibiting the expression of Cdk4and stops cell to enter S pHase. Overexpression Pax6also leads to this pHenomenon but not as remarkable as VP. Furthermore, the ability to promote or inhibit other eye-field transcription factors is also different between VP and Pax6. According to our results, we infer that it is the participation of the development process of Bufo raddei that makes VP survived in nature selection.According to our results, following inferences can be made. As a unique protein, VP can be stable in Bufo raddei because it participate in the development process of Bufo raddei and performs a series of unique molecular mechanisms. These mechanisms were retained by natural selection because they are conducive to the survival of Bufo raddei. According to the structure characteristics of VP protein itself and the properties of the cells after overexpressing the VP protein, we can speculated that VP recognizes identical downstream genes with Pax6and shows more effective activity. Genes, such as Six3and Sox2, may been regulated by VP as well as Pax6. This way of special regulation may lead to new signaling pathways, involved in the development process of Bufo raddei eyes. Such incidents occured several times during the evolution process of vertebrates, finally form the diversity of Pax6gene family.