P-028 Loss of the m6A methyltransferase METTL5 impairs spermiogenesis and male fertility

Abstract

Abstract Study question Whether and how METTL5 regulates germ cell development during spermatogenesis. Summary answer METTL5 is required for spermiogenesis. Loss of METTL5 resulted in teratozoospermia and male infertility via reduced translation of acrosome and flagellum formation proteins. What is known already The roles of m6A modifications on mRNA in spermatogenesis have been extensively studied. It was reported that METTL5 knockout mice showed the brain development defect and sterility of 16-week male mice. However, the detailed mechanism of METTL5 affecting male fertility remains elusive. Study design, size, duration Mettl5 KO mice were kindly gifted from Prof. Shuibin Lin of The First Affiliated Hospital of Sun Yat-sen University. Heterozygotes of Mettl5 mice were used to generate Mettl5 homozygous knockout mice. The phenotype of KO mice was assessed. Ribosomal sequencing, proteomics analysis and further validation of protein translation were performed to explore the mechanism. Participants/materials, setting, methods Fertility assessment, sperm parameter analyses, sperm nuclear morphology analysis, Transmission electron microscopy (TEM), tissue Collection and histological analysis, protein extraction and western blot analysis, immunofluorescence studies, cDNA synthesis and qRT-PCR, in vitro fertilization (IVF) were used in this study. Main results and the role of chance Here we reported that methyltransferase-like 5 (METTL5) is involved in spermiogenesis as a methyltransferase mediating m6A modification on rRNA. Mettl5 knockout mice were infertile with teratozoospermia. The acrosome in the sperm head was absent with reduced sperm motility. Furthermore, the fertilization ability of sperm in the IVF experiment failed. Mechanistically, the level of rRNA m6A modification was significantly decreased in the testes of Mettl5 KO mice. The translational efficiency and protein levels of acrosome and flagellum formation proteins such as FSIP2, ODF2, GK2, PGK2, and AKAP4 were significantly reduced when METTL5 was depleted. Limitations, reasons for caution The METTL5 mutation in the patient with teratozoospermia was not examined in the present study Wider implications of the findings The rRNA m6A modification is also involved in regulating spermatogenesis by METTL5. This study highlights the critical role of rRNA epigenetic modifications during spermatogenesis and provides novel theoretical explanations for the m6A modifications. Trial registration number Not applicable