Mus musculus
The mitosis-to-meiosis switch during spermatogenesis requires dynamic changes in the gene expression program. However, how meiotic transcriptional and post-transcriptional machinery are regulated during this transition remains elusive. Herein, we report that METTL16, an N6-methyladenosine (m6A) writer, is required for mitosis-to-meiosis transition during spermatogenesis. Germline-conditional knockout of Mettl16 in male mice impairs spermatogonia differentiation and meiosis initiation. Mechanistically, METTL16 could interact with splicing factors to regulate the alternative splicing of meiotic-related genes, such as Stag3 and Stra8. In addition, ribosome profiling (Ribo-seq) reveals the translation efficiency of many meiotic genes in METTL16-deficient testes are dysregulated. m6A-seq shows that ablation of METTL16 causes an upregulation of the m6A-enriched transcripts and a downregulation of the m6A-depleted transcripts, similar to Meioc- and/or Ythdc2 mutants, but interestingly, the translational efficiency is comparable between m6A-enriched and m6A-depleted transcripts. Further in vivo and in vitro experiments demonstrate that the methyltransferase activity site (PP185-186AA) of METTL16 is necessary for spermatogenesis and METTL16 interacts with the MEIOC/YTHDC2/RBM46 complex to be involved in spermatogenesis. Collectively, our data support a molecular model wherein m6A writer METTL16-mediated alternative splicing and translational efficiency regulation are required for controlling the mitosis-to-meiosis germ cell fate decision in mice, with implications for understanding meiosis-related male fertility disorders.