YTHDF2 promotes DNA damage repair by positively regulating the histone methyltransferase SETDB1 in spermatogonia.

Genomic integrity is critical for sexual reproduction, ensuring correct transmission of parental genetic information to the descendant. To preserve genomic integrity, germ cells have evolved multiple DNA repair mechanisms, together termed DNA damage response. RNA N6-methyladenosine (m6A) is the most abundant mRNA modification in eukaryotic cells that plays important roles in DNA damage response, and YTHDF2 is a well-acknowledged m6A reader protein regulating the mRNA decay and stress response. Despite this, the correlation between YTHDF2 and DNA damage response in germ cells, if any, remains enigmatic. Here, by employing a Ythdf2-conditional knockout (cKO) mouse model as well as a Ythdf2-null GC-1 mouse spermatogonial cell line, we explored the role and the underlying mechanism for YTHDF2 in spermatogonial DNA damage response. We identified that despite no evident testicular morphological abnormalities under the normal circumstance, conditional mutation of Ythdf2 in adult male mice sensitized germ cells, including spermatogonia, to etoposide-induced DNA damage. Consistently, Ythdf2-KO GC-1 cells displayed the increased sensitivity and apoptosis in response to DNA damage, accompanied by the decreased SETDB1 (a histone methyltransferase) and H3K9me3 levels. Setdb1 knockdown in GC-1 cells generated the similar phenotype, but its overexpression in Ythdf2-null GC-1 cells alleviated the sensitivity and apoptosis in response to DNA damage. Taken together, these results demonstrate that the m6A reader YTHDF2 promotes DNA damage repair by positively regulating the histone methyltransferase SETDB1 in spermatogonia, which provides novel insights into the mechanisms underlying spermatogonial genome integrity maintenance and therefore contributes to safe reproduction.