5-Aza deoxyCytidine-induced inhibition of differentiation of spermatogonia into spermatocytes in the mouse.

In order to explore the significance of DNA methylation in proliferation and differentiation of germ cells in testis, 5-aza,2'-deoxyCytidine (5-azaCdR), a hypomethylating agent, was administered in vivo to neonatal mice having only spermatogonial (premeiotic) cells. End-labeling of the MspI, HpaII, and HhaI digested DNA revealed considerable loss of methylation following the treatment. Cellular and histological preparations of the testis showed complete inhibition of differentiation into spermatocytic stage. Analysis of protein synthesis in the treated and control testis by growing the cells in 35S-Methionine medium and resolving the lysate by SDS-PAGE revealed that the programme of expression of at least 5 polypeptides (35.0, 31.5, 27.0, 22.5, and 18.0 KD) was altered as a result of 5-azaCdR incorporation. It appears that DNA methylation plays a critical role in the differentiation of gonia into primary spermatocytes.