YTHDC2 regulates spermatogenesis through promoting the translation of N6-methyladenosine-modified RNA

N6-methyladenosine (m6A) is the most common internal modification in eukaryotic mRNA. It is dynamically installed and removed, and acts as an essential layer of mRNA metabolism, regulating biological processes including stem cell pluripotency, cell differentiation, and energy homeostasis. m6A is recognized by selective binding proteins; YTHDF1 and YTHDF3 work in concert to promote the translation of m6A-containing mRNAs, YTHDF2 expedites mRNA decay, and YTHDC1 affects the splicing of its targets. The biological function of YTHDC2, the final member of the YTH protein family, remains unknown. We report that YTHDC2 selectively binds m6A along its consensus motif GGACU. YTHDC2 promotes translation of its targets, and associates with cellular fractions involved in translation initiation. Ythdc2 knockout mice are infertile and have significantly smaller testes compared to those of littermates. In the testes, Ythdc2 is temporally expressed as meiosis begins, and germ cells of Ythdc2 knockout mice do not develop past the spermatogonium stage. Thus, YTHDC2 is an m6A binding protein that plays essential roles in spermatogenesis.