m⁶ A reader protein YTHDF2 regulates spermatogenesis by timely clearance of phase-specific transcripts

Area of Science:

• Reproductive Biology
• Molecular Biology
• Epigenetics

Background:

• The regulation of messenger RNA (mRNA) methylation, specifically N6-methyladenosine (m6A) modification, is vital for mammalian spermatogenesis.
• YTHDF2, an m6A reader protein, has an incompletely understood role in this process due to a lack of suitable experimental models.

Purpose of the Study:

• To investigate the function of YTHDF2 in spermatogenesis using a conditional knockout mouse model.
• To elucidate the molecular mechanisms by which YTHDF2 influences sperm development.

Main Methods:

• Generation of Ythdf2 germ cell conditional knockout mice by crossing Ythdf2-floxed mice with Vasa-Cre and Stra8-Cre lines.
• Phenotypic analysis using HE staining, immunofluorescence, and Western blotting.
• Sperm function assessment via CASA, IVF, and ICSI.
• Transcriptome and molecular mechanism exploration using RNA-seq, YTHDF2-RIP-seq, and qRT-PCR.

Main Results:

• YTHDF2 is highly expressed in spermatogenic cells.
• Germ cell-specific knockout of YTHDF2 resulted in male sterility with severe sperm malformation, motility defects, and loss of fertilization ability.
• Loss of YTHDF2 led to the accumulation of normally degraded m6A-modified transcripts in pachytene spermatocytes, affecting transcriptional regulation pathways and disturbing the transcriptome of later spermatid stages.

Conclusions:

• YTHDF2 plays a critical role in spermatogenesis by ensuring the timely degradation of phase-specific transcripts.
• This timely turnover of transcripts is essential for the proper progression of male germ cell development.