Dynamic expression profile of DNA methyltransferases in rat testis development

DNA methyltransferases (Dnmts) are unique and perform specific functions during male germ cell development. To further characterize the significance of Dnmts in the events leading to production of spermatozoa, we investigated whether the expression patterns in Dnmt1, Dnmt3a, Dnmt3b and Dnmt3l were apparent in rat testes at different time points during development. The qRT-PCR results showed that expression levels of Dnmt3a and Dnmt3l were abundant before birth and were present at the highest levels in testes tissue at 18.5 days postcoitus (dpc), and gradually decreased from day 0 postpartum (dpp) to 90 dpp. Expression of Dnmt1 and Dnmt3b reached a peak after birth (P <0.01), and then gradually reduced until adulthood. Western blotting and immunolocalization analysis of Dnmt3a and Dnmt3b further confirmed the differential expression and localization of the two proteins during rat testis development. The dynamic expression profile of Dnmts implies specific and potentially nonredundant roles for each of these enzymes in the developing rat testis.