GCNA preserves genome integrity and fertility across species

Abstract

SUMMARYThe propagation of species depends on the ability of germ cells to protect their genome in the face of numerous exogenous and endogenous threats. While these cells employ a number of known repair pathways, specialized mechanisms that ensure high-fidelity replication, chromosome segregation, and repair of germ cell genomes remain incompletely understood. Here, we identify Germ Cell Nuclear Acidic Peptidase (GCNA) as a highly conserved regulator of genome stability in flies, worms, zebrafish, and humans. GCNA contains a long acidic intrinsically disordered region (IDR) and a protease-like SprT domain. In addition to chromosomal instability and replication stress, GCNA mutants accumulate DNA-protein crosslinks (DPCs). GCNA acts in parallel with a second SprT domain protein Spartan. Structural analysis reveals that while the SprT domain is needed to limit meiotic and replicative damage, most of GCNA’s function maps to its IDR. This work shows GCNA protects germ cells from various sources of damage, providing novel insights into conserved mechanisms that promote genome integrity across generations.HighlightsGCNA ensures genomic stability in germ cells and early embryos across speciesGCNA limits replication stress and DNA double stranded breaksGCNA restricts DNA-Protein Crosslinks within germ cells and early embryosThe IDR and SprT domains of GCNA govern distinct aspects of genome integrityGraphic Abstract

Topoisomerase Assays

“…The RADAR assay is readily adapted for studies of specific adducts and cell types for diverse applications, including analyses of the roles of SUMO (Sun et al, 2020) and SPRTN (Fielden et al, 2020) in resolution of topoisomerase I−DNA adducts; detection of endogenous adducts resolved by GCNA (Bhargava et al, 2020); characterization of covalent DNA and RNA adducts formed by TOP3B (Saha et al, 2020); identification of roles of adducts formed by HMCES in protection of abasic sites in single-stranded DNA (Mohni et al, 2019); and establishment of cell cycle−dependent crosslinking of the Epstein-Barr virus EBNA1 regulatory protein to viral episomes (Dheekollu et al, 2021).…”