IGF2BP3 recognizes m6A to regulate histone-to-protamine replacement during mouse sperm development

Post-meiotic development of spermatids is under the control of a sophisticated RNA metabolic network, wherein the N6-methyladenosine (m 6 A) modification of mRNA, and proteins that bind to it, exert crucial functions in regulating sperm development from spermatogonia to spermatocytes. However, which m 6 A recognition proteins are involved in male post-meiotic spermiogenesis, and via which regulatory mechanisms, remains largely unknown. Here, we uncover the involvement of the m 6 A reader protein IGF2BP3 in the regulation of post-meiotic spermatid development. Genetic ablation of Igf2bp3 results in spermatogenesis defects, leading to male sub-fertility or even infertility. Mechanistically, IGF2BP3 loss-of-function leads to the excessive translation of its target RNAs associated with histone-to-protamine replacement, particularly Dot1l and Hdac11 . IGF2BP3 translationally represses these targets through its m 6 A-binding property and through its interaction with its binding partner YBX2. Sperm developmental defects of IGF2BP3 knockout mouse can be rescued by siRNAs targeting Dot1l and Hdac11 . Collectively, our findings define the essential role of IGF2BP3-dependent regulation of protein biosynthesis in histone-to-protamine replacement during spermiogenesis, helping to understand the functions of m 6 A RNA modification in sperm development and male fertility.