The DNA damage checkpoint pathway promotes extensive resection and nucleotide synthesis to facilitate homologous recombination repair and genome stability in fission yeast

Abstract

DNA double-strand breaks (DSBs) can cause chromosomal rearrangements and extensive loss of heterozygosity (LOH), hallmarks of cancer cells. Yet, how such events are normally suppressed is unclear. Here we identify roles for the DNA damage checkpoint pathway in facilitating homologous recombination (HR) repair and suppressing extensive LOH and chromosomal rearrangements in response to a DSB. Accordingly, deletion of Rad3ATR, Rad26ATRIP, Crb253BP1 or Cdc25 overexpression leads to reduced HR and increased break-induced chromosome loss and rearrangements. We find the DNA damage checkpoint pathway facilitates HR, in part, by promoting break-induced Cdt2-dependent nucleotide synthesis. We also identify additional roles for Rad17, the 9-1-1 complex and Chk1 activation in facilitating break-induced extensive resection and chromosome loss, thereby suppressing extensive LOH. Loss of Rad17 or the 9-1-1 complex results in a striking increase in break-induced isochromosome formation and very low levels of chromosome loss, suggesting the 9-1-1 complex acts as a nuclease processivity factor to facilitate extensive resection. Further, our data suggest redundant roles for Rad3ATR and Exo1 in facilitating extensive resection. We propose that the DNA damage checkpoint pathway coordinates resection and nucleotide synthesis, thereby promoting efficient HR repair and genome stability.

Maternal DCAF2 is crucial for maintenance of genome stability during the first cell cycle in mice

“…Biochemically, DCAF2 could play two roles in the maintenance of zygotic genome integrity. First, drastic genome reprogramming in zygotes, particularly in the male pronucleus, causes DNA double-strand breaks; DCAF2 may be directly involved in the timely repair of these DNA lesions to ensure embryonic cell cycle progression, as has been observed in cultured somatic cells (Blaikley et al, 2014;Han et al, 2015). Second, DCAF2 functions as a substrate adaptor mediating CRL4-dependent ubiquitylation and degradation of the DNA replication licensing factor CDT1, thereby preventing the DNA damage caused by re-replication (Higa et al, 2006;Jin et al, 2006).…”

The endonuclease homolog OsRAD1 promotes accurate meiotic double-strand break repair by suppressing non-homologous end joining

“…How the 9-1-1 complex prevents nonhomologous associations at the molecular level is currently unknown. Studies in yeast have indicated that 9-1-1 serves as a stimulatory factor for both Dna2-Sgs1 and Exo1 during DNA resection (Blaikley et al, 2014;Ngo et al, 2014). Moreover, the human RAD1 was proved to have an exonuclease activity in vitro (Parker et al, 1998).…”

A novel protein, Rsf1/Pxd1, is critical for the single‐strand annealing pathway of double‐strand break repair in Schizosaccharomyces pombe

“…The fission yeast S. pombe has many advantages as a model system for investigation of DNA repair mechanism (Forsburg, 2005). To address the SSA pathway in fission yeast, we and other groups established a chromosomebased SSA repair system in S. pombe (Osman et al, 1996;Blaikley et al, 2014). Recently, Antony M. Carr's group established a novel S. pombe SSA assay (Watson et al, 2011;2013).…”