C. elegans BRC-1-BRD-1 functions at an early step of DSB processing and inhibits supernumerary crossovers during male meiosis

Abstract

Meiosis is regulated in a sex-specific manner to produce two distinct gametes, sperm and oocytes, for sexual reproduction. To determine how meiotic recombination is regulated in spermatogenesis, we analyzed the meiotic phenotypes of mutants in the tumor suppressor E3 ubiquitin ligase BRC-1-BRD-1 complex in Caenorhabditis elegans male meiosis. Unlike in mammals, this complex is not required for meiotic sex chromosome inactivation, the process whereby hemizygous sex chromosomes are transcriptionally silenced. Interestingly, brc-1 and brd-1 mutants showed meiotic recombination phenotypes that are largely opposing to those previously reported for female meiosis. Fewer meiotic recombination foci marked by the recombinase RAD-51 were observed in brc-1 and brd-1 mutants, and the reduction in RAD-51 foci can be suppressed by mutation of nonhomologous end joining proteins. We show that concentration of BRC-1-BRD-1 to sites of meiotic recombination is dependent on DNA end resection, suggesting that BRC-1-BRD-1 regulates the processing of meiotic double strand breaks to promote repair by homologous recombination, similar to a role for the complex in somatic cells. We also show that BRC-1-BRD-1 is important to promote progeny viability when male meiosis is perturbed by mutations that block the pairing and synapsis of different chromosome pairs, although the complex is not required to stabilize the RAD-51 filament as in female meiosis under the same conditions. Analyses of crossover designation and formation reveal that BRC-1-BRD-1 inhibits supernumerary crossovers when meiosis is perturbed. Together, our findings suggest that BRC-1-BRD-1 regulates different aspects of meiotic recombination in male and female meiosis.