# Prenatal cadmium exposure and male infertility in mice: A multi-generational mechanistic study

## TL;DR

Prenatal cadmium exposure in mice leads to male infertility across multiple generations by affecting hormone production and protein degradation.

## Contribution

Identifies RAPSN as a novel ubiquitin E3 ligase and reveals m6A modification's role in multi-generational male subfertility.

## Key findings

- Prenatal cadmium exposure causes male subfertility in F1–F3 offspring.
- RAPSN is a novel E3 ligase mediating NR4A1 ubiquitination in testes.
- m6A modification increases RAPSN expression, contributing to subfertility.

## Abstract

Male infertility affects approximately one in seven couples worldwide. Prenatal cadmium (Cd) exposure has been shown to affect offspring phenotypes and increase susceptibility to diseases later in life. However, the effects of prenatal Cd exposure on multi-generational offspring fertility and the mechanisms remain unknown. A novel murine multi-generational (F1–F3 offspring) male subfertility model induced by prenatal Cd exposure was developed. The levels of testosterone and steroidogenic enzymes were also lower in these offspring’s testes. The ubiquitin-dependent degradation of NR4A1, the upstream transcription factor regulating steroidogenic enzymes, was enhanced across generations upon prenatal Cd exposure. After treatment with MG132, an inhibitor of the ubiquitin-proteasome system, the levels of NR4A1 and steroidogenic enzymes were higher in offspring testes with prenatal Cd exposure. Based on the analysis of the UbiBrowser database and testicular global transcriptome, RAPSN was identified as a novel ubiquitin E3 ligase containing the RING-H2_Rapsyn domain that mediates multi-generational testicular NR4A1 ubiquitination. m6A epitranscriptome analysis revealed that prenatal Cd exposure upregulated RAPSN expression in multi-generational offspring testes, and was attributed to a higher level of m6A modification of Rapsn mRNA. Furthermore, there was a lower level of YTHDC2, a m6A reader, in the multi-generational offspring testes with prenatal Cd exposure. Prenatal and postnatal testicular YTHDC2 overexpression reduced the stability of m6A-methylated Rapsn mRNA to downregulate RAPSN expression in F1–F3 testes. Overall, YTHDC2 reduction-mediated increment in m6A-methylated Rapsn mRNA contributed to prenatal Cd-enhanced multi-generational susceptibility to male subfertility.

Image 1

•Prenatal Cd exposure induces male subfertility in multigenerational offspring.•Testicular NR4A1 ubiquitin drives prenatal Cd-induced male offspring subfertility.•RAPSN is firstly identified as testicular E3 driving offspring NR4A1 ubiquitin.•Prenatal Cd enhances m6A modification to elevate RAPSN level in offspring testes.

Prenatal Cd exposure induces male subfertility in multigenerational offspring.

Testicular NR4A1 ubiquitin drives prenatal Cd-induced male offspring subfertility.

RAPSN is firstly identified as testicular E3 driving offspring NR4A1 ubiquitin.

Prenatal Cd enhances m6A modification to elevate RAPSN level in offspring testes.