Expression of Regulatory Homeobox Genes during Retina Regeneration in Adult Newts

We studied molecular-genetic mechanisms of retina regeneration in amphibians and, specifically, expression of the homeobox genes Pax6, Prox1, and Six3 in normal development and during retina regeneration in the newt. Based on the structural analysis of genes in closely related amphibian species, primers were constructed that flank certain regions of these genes. PCR fragments of calculated length were obtained. The relationship of PCR products to the above genes was confirmed by sequencing. A comparative PCR analysis of expression of Pax6, Prox1, and Six3 was carried out in the native and regenerating newt retina, which allowed estimation of the level of expression. cDNA libraries obtained from the native and regenerating retina were used as templates. The libraries were preliminary standardized according to glyceraldehydes-3-phosphate dehydrogenase, an enzyme of general cell metabolism. The genes we studied were expressed in both native and regenerating retina. The level of Pax6 and Prox1 expression increased during regeneration, while that of Six3 decreased. The decrease in the level of Six3 expression could be due to antagonistic interrelations of Prox1 and Six3. The changed level of Prox1 and Six3 expression is a new fact and requires further studies. The interactions between these and other regulatory genes and localization of their expression in the cells of native and regenerating retina will be studied using in situ hybridization and immunohistochemistry.