Homologous recombination suppresses transgenerational DNA end resection and chromosomal instability in fission yeast

• Published in: Nucleic acids research Vol. 51; no. 7; pp. 3205 - 3222
• Main Authors: Pai, Chen-Chun, Durley, Samuel C, Cheng, Wei-Chen, Chiang, Nien-Yi, Peters, Jennifer, Kasparek, Torben, Blaikley, Elizabeth, Wee, Boon-Yu, Walker, Carol, Kearsey, Stephen E, Buffa, Francesca, Murray, Johanne M, Humphrey, Timothy C
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 24.04.2023
• Subjects: Chromosomal Instability; DNA Breaks, Double-Stranded; DNA Repair; Genomics; Homologous Recombination; Humans; Schizosaccharomyces - genetics; Schizosaccharomyces - metabolism
• ISSN: 0305-1048; 1362-4962; 1362-4962
• DOI: 10.1093/nar/gkad160

Abstract Chromosomal instability (CIN) drives cell-to-cell heterogeneity, and the development of genetic diseases, including cancer. Impaired homologous recombination (HR) has been implicated as a major driver of CIN, however, the underlying mechanism remains unclear. Using a fission yeast model system, we establish a common role for HR genes in suppressing DNA double-strand break (DSB)-induced CIN. Further, we show that an unrepaired single-ended DSB arising from failed HR repair or telomere loss is a potent driver of widespread CIN. Inherited chromosomes carrying a single-ended DSB are subject to cycles of DNA replication and extensive end-processing across successive cell divisions. These cycles are enabled by Cullin 3-mediated Chk1 loss and checkpoint adaptation. Subsequent propagation of unstable chromosomes carrying a single-ended DSB continues until transgenerational end-resection leads to fold-back inversion of single-stranded centromeric repeats and to stable chromosomal rearrangements, typically isochromosomes, or to chromosomal loss. These findings reveal a mechanism by which HR genes suppress CIN and how DNA breaks that persist through mitotic divisions propagate cell-to-cell heterogeneity in the resultant progeny.