Fancm regulates meiotic double-strand break repair pathway choice in mammals

Abstract

Meiotic crossovers are required for accurate chromosome segregation and to produce new allelic combinations. Meiotic crossover numbers are tightly regulated within a narrow range, despite an excess of initiating DNA double-strand breaks. Here, we describe the tumour suppressor FANCM as a meiotic anti-crossover factor in mammals. Crossover analyses with single-gamete and pedigree datasets both reveal a genome-wide increase in crossover frequencies in Fancm-deficient mice. Gametogenesis is heavily perturbed in Fancm loss of function mice, which is consistent with the reproductive defects reported in humans with biallelic FANCM mutations. A portion of the gametogenesis defects can be attributed to the cGAS-STING pathway. Despite the gametogenesis phenotypes in Fancm mutants both sexes were capable of producing offspring. We propose that the anti-crossover function and role in gametogenesis of Fancm are separable and will inform diagnostic pathways for human genomic instability disorders.

SSNIP-seq: A simple and rapid method for isolation of single-sperm nucleic acid for high-throughput sequencing

“…The resulting nuclei from all samples are stained with DAPI and sorted using flow cytometry to isolate the haploid nuclei from the testis sample, which can then be used as material for a variety of high-throughput sequencing techniques ( Fig 1 ). We have successfully used these nuclei in bulk ATAC-seq, scATAC-seq and single nuclei CNV experiments for mouse haploid nuclei [ 13 ]. We propose that the protocol can be easily adapted for mature human sperm.…”