Localization of the PITX2 gene expression in human eye cells in the course of prenatal development

The pattern of the PITX2 gene expression was studied in the cornea, lens, retina, iridocorneal complex (ICC), and eye coats of human fetuses at weeks 9.5-22 of intrauterine development. Using the PCR method, PITX2 expression in all these tissues was revealed already at the earliest stage studied (9.5 weeks), being especially strong in the anterior eye complex (the cornea and lens) and weaker in the retina and sclera. The level of PITX2 expression in all eye tissues slightly decreased by week 15, increased to a high level in the ICC on week 18, and further decreased in all tissues by week 22. Using cDNA derived from the whole eyes of 8-, 9-, 10.5-, and 11-week fetuses, the expression of two PITX2 isoforms specific for eye tissues (A and B) was revealed. By means of in situ hybridization, the PITX2 mRNA was localized in the eye tissues of ectodermal and neuroectodermal origin.