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

## TL;DR

This study shows that the protein IGF2BP3 helps regulate sperm development in mice by controlling the translation of specific genes involved in replacing histones with protamines.

## Contribution

The study identifies IGF2BP3 as a key m6A reader protein involved in post-meiotic spermiogenesis through translational repression of Dot1l and Hdac11.

## Key findings

- IGF2BP3 is specifically expressed in post-meiotic spermatids in mouse testes.
- Loss of IGF2BP3 causes male infertility-like symptoms and defects in histone-to-protamine replacement.
- siRNAs targeting Dot1l and Hdac11 rescue sperm developmental defects in IGF2BP3 knockout mice.

## Abstract

Post-meiotic development of spermatids is under the control of a sophisticated RNA metabolic network, wherein the N6-methyladenosine (m6A) modification of mRNA, and proteins that bind to it, exert crucial functions in regulating sperm development from spermatogonia to spermatocytes. However, which m6A recognition proteins are involved in male post-meiotic spermiogenesis, and via which regulatory mechanisms, remains largely unknown. Here, we uncover the involvement of the m6A 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 m6A-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 m6A RNA modification in sperm development and male fertility.

The functional and regulatory roles of RNA N6-methyladenosine (m6A) modification recognition proteins in post-meiotic spermiogenesis remain unclear. This study shows that in murine post-meiotic spermatids, the m6A reader IGF2BP3 together with its cofactor YBX2 regulates biosynthesis of proteins associated with the histone-to-protamine transition.

IGF2BP3 is specifically expressed in post-meiotic spermatids in mouse testes.Male mice lacking IGF2BP3 display composite phenotypes resembling human oligoasthenoteratozoospermia.The IGF2BP3-YBX2 complex translationally represses m⁶A-modified RNAs, such as Dot1l and Hdac11, that are essential for histone-to-protamine exchange and spermatid maturation.siRNAs targeting DOT1L and HDAC11 significantly rescue the sperm developmental defects in Igf2bp3-KO mouse.

IGF2BP3 is specifically expressed in post-meiotic spermatids in mouse testes.

Male mice lacking IGF2BP3 display composite phenotypes resembling human oligoasthenoteratozoospermia.

The IGF2BP3-YBX2 complex translationally represses m⁶A-modified RNAs, such as Dot1l and Hdac11, that are essential for histone-to-protamine exchange and spermatid maturation.

siRNAs targeting DOT1L and HDAC11 significantly rescue the sperm developmental defects in Igf2bp3-KO mouse.

The m6A reader protein IGF2BP3 cooperates with YBX2 to facilitate correct spermiogenesis by suppressing translation of Dot1l and Hdac11 mRNAs.