DNMT enzymes differentially alter global DNA methylation in a stage-dependent manner during spermatogenesis

DNA methylation plays important roles during spermatogenesis. This mechanism includes maintenance and de novo methylation which are catalysed by DNA methyltransferase enzymes. DNMT1 plays role in maintenance methylation, while DNMT3A, DNMT3B and DNMT3L are primarily responsible for de novo methylation. Both maintenance and de novo methylation processes appears during primordial germ cell development and spermatogenesis. However, the function(s) of the methylation and DNMTs during spermatogenesis still remain elusive. The aim of the study was to evaluate the relationship between DNMTs levels and global DNA methylation in total testis and during spermatogenesis. For this purpose, DNMTs were analysed using Western blot and immunohistochemistry techniques. We also analysed global DNA methylation level by 5mC staining. We found that DNMTs expression and global DNA methylation levels were significantly differed in total testes and spermatogenetic cells in a stage-dependent manner. DNMT3B and DNMT3L were more abundant in testes, while DNMT1 and DNMT3A were comparatively low. Interestingly, no DNMTs signal was seen in elongated spermatid whereas global DNA methylation was at the highest level. To understand the meaning of differential expressions of DNMTs in the testes, further molecular biological studies are required.