Regulation of m6A transcripts by the 3ʹ→5ʹ RNA helicase YTHDC2 is essential for a successful meiotic program in the mammalian germline

N6-methyladenosine (m6A) is an essential internal RNA modification that is critical for gene expression control in most organisms. Proteins with a YTH domain recognize m6A marks and are mediators of molecular functions like RNA splicing, mRNA decay and translation control. Here we demonstrate that YTH domain-containing 2 (YTHDC2) is an m6A reader that is essential for male and female fertility in mice. In mutant males, mitotic spermatogonia fail to differentiate into meiotic spermatocytes. Analysis identifies transcripts upregulated in the Yhtdc2 mutant testes to be those that are expressed in purified spermatogonia, while high-throughput mapping of the m6A transcriptome in the mouse male germline demonstrates the upregulated transcripts to be those that are enriched in m6A marks. Our biochemical studies indicate that YTHDC2 is an RNAinduced ATPase that fuels its 3ʹ→5ʹ RNA helicase activity. Interestingly, we find an RNA-independent interaction between the 5ʹ→3ʹ exoribonuclease XRN1 and the Ankyrin repeat of YTHDC2 that is wedged in between the two RecA helicase domains. Our studies reveal a role for YTHDC2 in modulating the levels of m6A-modified germline transcripts that is essential for successful meiosis. RNA sequencing was used to identify transcript abundance differences between Ythdc2 mutant and wt mice. The distribution of m6A in testicular transcripts was analyzed by m6A RNA-Seq. RNA Bind-N-Seq analysis was performed to determine the YTH domain bound sequences.