Critical roles of mRNA m6A modification and YTHDC2 expression for meiotic initiation and progression in female germ cells.

Meiotic entry and progression require dynamic regulation of germline gene expression. m6A on mRNAs and recognition by YTHDC2 has been known as post-transcriptional regulatory complex, but the roles of this regulator remain unclear for meiotic initiation and progression in female germ cells (FGCs). This study showed that m6A modification occurred mainly in FGCs rather than ovarian somatic cells (SOMAs), and m6A levels in FGCs increased significantly with meiotic initiation. m6A inhibition suppressed expression of the meiotic markers and affected the percent of FGCs at zygotene, pachytene and diplotene stage respectively. YTHDC2 expression also increased in the same pattern with m6A. Ythdc2 knockdown decreased the percent of STRA8-positive FGCs and altered the percent of FGCs at zygotene and pachytene stage respectively. Taken together, these results suggest that mRNA m6A modification and YTHDC2 expression are essential for meiotic initiation and progression in FGCs.