YTHDC2 serves a distinct late role in spermatocytes during germ cell differentiation

Posttranscriptional regulation of gene expression by RNA-binding proteins can enhance the speed and robustness of cell state transitions by controlling RNA stability, localization, or if, when, or where mRNAs are translated. The RNA helicase YTHDC2 is required to shut down components of the mitotic program to facilitate a proper switch from mitosis to meiosis in mouse germ cells. Here, we show that YTHDC2 has a second essential role in promoting meiotic progression in late spermatocytes. Inducing conditional knockout of <i>Ythdc2</i> during the first wave of spermatogenesis, after initiation of meiotic prophase, allowed <i>YTHDC2</i>-deficient germ cells to advance to the pachytene stage and properly express many meiotic markers. However, the <i>YTHDC2</i>-deficient spermatocytes mis-expressed a number of genes, some up-regulated and some down-regulated, failed to transition to the diplotene stage, and then quickly died. Coimmunoprecipitation experiments revealed that YTHDC2 interacts with several RNA-binding proteins in early or late spermatocytes, with many of the interacting proteins, including MEIOC, localizing to granules, similar to YTHDC2. Our findings suggest that YTHDC2 collaborates with other RNA granule components to facilitate proper progression of germ cells through multiple steps of meiosis via mechanisms influencing posttranscriptional regulation of RNAs.