Protein arginine methyltransferase 5 (Prmt5) is required for germ cell survival during mouse embryonic development

In mammals, germ cells undergo massive epigenetic remodeling during fetal development. However, the physiological functions of epigenetic modification in germ cell development remain unclear. In this study, we found that protein arginine methyltransferase 5 (Prmt5) was abundantly expressed in the germ cells of both male and female gonads. Deletion of Prmt5 by crossing with Tnap-Cre mice resulted in germ cell depletion in adult mice. Germ cell loss was first observed between Embryonic Days 12.5 and 13.5 (E12.5 and E13.5), and very few of these cells remained at birth. Oct4, Sox2, and Nanog were abundantly expressed in Prmt5-deficient germ cells at E13.5 and E15.5, whereas the expression of these genes was dramatically decreased in control germ cells. Interestingly, the expression of meiosis-associated genes was virtually absent in Prmt5-deficient female germ cells at E13.5, whereas the expression of other germ cell-specific genes was not changed. Further study revealed that H4R3me2s was completely absent after Prmt5 inactivation, whereas the level of H3R2me2s was not changed in Prmt5-deficient germ cells. Collectively, this study demonstrated that Prmt5 plays critical roles in germ cell development that are required for germ cell survival during embryonic stages.