UC Davis

The Fanconi anemia (FA) DNA damage response (DDR) pathway regulate important cellular processes such as DNA replication, cell cycle control and DNA damage repair. Here we show that FANCD2, a key member of the FA DDR pathway, interacts with several important components of the germ-cell-specific Prmt5/piRNA pathways that orchestrate the repression of transposable elements (TEs). By using the Pou5f1-eGFP reporter mice, which marks pure populations of primordial germ cells (PGCs), we demonstrate that FA deficiency results in de-repression of TEs, depletion of PGCs, and defective spermatogenesis and oogenesis. Fancd2–KO PGCs exhibited excessive DNA damage and exacerbated apoptosis. Mechanistically, we observed a significant reduction of PRMT5-catalyzed H2A/H4R3me2s marks on the LINE1 TEs in E10.5 PGCs of Fancd2-KO; Pou5f1-eGFP and Fanca-KO;Pou5f1-eGFP embryos. Furthermore, we utilized the Fancd2-KI model to show that Fancd2 and Prmt5 co-occupied the promoter of LINE1 in WT PGCs, and that this co-occupancy was lost in FA-deficient (Fanca-KO) PGCs. These results suggest that the FA pathway takes part in TE repression in early PGCs, likely through a mechanism involving Fancd2-facilitated, Prmt5-catalyzed repressive H2A/H4R3me2s marks on TEs.