SLFN11 is Widely Expressed in Pediatric Sarcoma and Induces Variable Sensitization to Replicative Stress Caused By DNA-Damaging Agents

DNA double-strand breaks (DSBs) are the most deleterious form of DNA damage and are repaired through non-homologous end-joining (NHEJ) or homologous recombination (HR). Repair initiation, regulation and communication with signaling pathways require several histone-modifying and chromatin-remodeling complexes. In budding yeast, this involves three primary complexes: INO80-C, which is primarily associated with HR, SWR1-C, which promotes NHEJ, and RSC-C, which is involved in both pathways as well as the general DNA damage response. Here we identify ARP6 as a factor involved in DSB repair through an RSC-C-related pathway. The loss of ARP6 significantly reduces the NHEJ repair efficiency of linearized plasmids with cohesive ends, impairs the repair of chromosomal breaks, and sensitizes cells to DNA-damaging agents. Genetic interaction analysis indicates that ARP6, MRE11 and RSC-C function within the same pathway, and the overexpression of ARP6 rescues rsc2∆ and mre11∆ sensitivity to DNA-damaging agents. Double mutants of ARP6, and members of the INO80 and SWR1 complexes, cause a significant reduction in repair efficiency, suggesting that ARP6 functions independently of SWR1-C and INO80-C. These findings support a novel role for ARP6 in DSB repair that is independent of the SWR1 chromatin remodeling complex, through an apparent RSC-C and MRE11-associated DNA repair pathway.

Download Full-text

Low Replicative Stress Triggers Cell-Type Specific Inheritable Advanced Replication Timing

International Journal of Molecular Sciences ◽

10.3390/ijms22094959 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4959

Author(s):

Lilas Courtot ◽

Elodie Bournique ◽

Chrystelle Maric ◽

Laure Guitton-Sert ◽

Miguel Madrid-Mencía ◽

...

Keyword(s):

Replication Timing ◽

Replication Stress ◽

Chromatin Accessibility ◽

Cell Type ◽

Replicative Stress ◽

Daughter Cells ◽

Origin Activation ◽

Cell Type Specific ◽

Cellular Identity ◽

Dna Replication Timing

DNA replication timing (RT), reflecting the temporal order of origin activation, is known as a robust and conserved cell-type specific process. Upon low replication stress, the slowing of replication forks induces well-documented RT delays associated to genetic instability, but it can also generate RT advances that are still uncharacterized. In order to characterize these advanced initiation events, we monitored the whole genome RT from six independent human cell lines treated with low doses of aphidicolin. We report that RT advances are cell-type-specific and involve large heterochromatin domains. Importantly, we found that some major late to early RT advances can be inherited by the unstressed next-cellular generation, which is a unique process that correlates with enhanced chromatin accessibility, as well as modified replication origin landscape and gene expression in daughter cells. Collectively, this work highlights how low replication stress may impact cellular identity by RT advances events at a subset of chromosomal domains.

Download Full-text

Nucleoside Analogues Are Potent Inducers of Pol V-mediated Mutagenesis

Biomolecules ◽

10.3390/biom11060843 ◽

2021 ◽

Vol 11 (6) ◽

pp. 843

Author(s):

Balagra Kasim Sumabe ◽

Synnøve Brandt Ræder ◽

Lisa Marie Røst ◽

Animesh Sharma ◽

Eric S. Donkor ◽

...

Keyword(s):

Mammalian Cells ◽

Mutation Frequency ◽

Nucleoside Analogues ◽

Cancer Therapies ◽

E Coli ◽

Replicative Stress ◽

Pol V ◽

Dna And Rna ◽

Sos Induction ◽

Anti Cancer

Drugs targeting DNA and RNA in mammalian cells or viruses can also affect bacteria present in the host and thereby induce the bacterial SOS system. This has the potential to increase mutagenesis and the development of antimicrobial resistance (AMR). Here, we have examined nucleoside analogues (NAs) commonly used in anti-viral and anti-cancer therapies for potential effects on mutagenesis in Escherichia coli, using the rifampicin mutagenicity assay. To further explore the mode of action of the NAs, we applied E. coli deletion mutants, a peptide inhibiting Pol V (APIM-peptide) and metabolome and proteome analyses. Five out of the thirteen NAs examined, including three nucleoside reverse transcriptase inhibitors (NRTIs) and two anti-cancer drugs, increased the mutation frequency in E. coli by more than 25-fold at doses that were within reported plasma concentration range (Pl.CR), but that did not affect bacterial growth. We show that the SOS response is induced and that the increase in mutation frequency is mediated by the TLS polymerase Pol V. Quantitative mass spectrometry-based metabolite profiling did not reveal large changes in nucleoside phosphate or other central carbon metabolite pools, which suggests that the SOS induction is an effect of increased replicative stress. Our results suggest that NAs/NRTIs can contribute to the development of AMR and that drugs inhibiting Pol V can reverse this mutagenesis.

Download Full-text

ATRX promotes heterochromatin formation to protect cells from G-quadruplex DNA-mediated stress

Nature Communications ◽

10.1038/s41467-021-24206-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yu-Ching Teng ◽

Aishwarya Sundaresan ◽

Ryan O’Hara ◽

Vincent U. Gant ◽

Minhua Li ◽

...

Keyword(s):

Dna Sequences ◽

Genome Stability ◽

Helicase Domain ◽

Quadruplex Dna ◽

Heterochromatin Formation ◽

Replicative Stress ◽

G4 Dna ◽

Mutation Burden ◽

G Quadruplex ◽

Dna Replication Stress

AbstractATRX is a tumor suppressor that has been associated with protection from DNA replication stress, purportedly through resolution of difficult-to-replicate G-quadruplex (G4) DNA structures. While several studies demonstrate that loss of ATRX sensitizes cells to chemical stabilizers of G4 structures, the molecular function of ATRX at G4 regions during replication remains unknown. Here, we demonstrate that ATRX associates with a number of the MCM replication complex subunits and that loss of ATRX leads to G4 structure accumulation at newly synthesized DNA. We show that both the helicase domain of ATRX and its H3.3 chaperone function are required to protect cells from G4-induced replicative stress. Furthermore, these activities are upstream of heterochromatin formation mediated by the histone methyltransferase, ESET, which is the critical molecular event that protects cells from G4-mediated stress. In support, tumors carrying mutations in either ATRX or ESET show increased mutation burden at G4-enriched DNA sequences. Overall, our study provides new insights into mechanisms by which ATRX promotes genome stability with important implications for understanding impacts of its loss on human disease.

Download Full-text

A stapled peptide mimetic of the CtIP tetramerization motif interferes with double-strand break repair and replication fork protection

Science Advances ◽

10.1126/sciadv.abc6381 ◽

2021 ◽

Vol 7 (8) ◽

pp. eabc6381

Author(s):

Anika Kuster ◽

Nour L. Mozaffari ◽

Oliver J. Wilkinson ◽

Jessica L. Wojtaszek ◽

Christina Zurfluh ◽

...

Keyword(s):

Strand Break ◽

Amino Acid Residues ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

Stapled Peptide ◽

Patients With Cancer ◽

Peptide Mimetic ◽

Dna Damaging Agents ◽

Stalled Replication Forks

Cancer cells display high levels of DNA damage and replication stress, vulnerabilities that could be exploited by drugs targeting DNA repair proteins. Human CtIP promotes homology-mediated repair of DNA double-strand breaks (DSBs) and protects stalled replication forks from nucleolytic degradation, thus representing an attractive candidate for targeted cancer therapy. Here, we establish a peptide mimetic of the CtIP tetramerization motif that inhibits CtIP activity. The hydrocarbon-stapled peptide encompassing amino acid residues 18 to 28 of CtIP (SP18–28) stably binds to CtIP tetramers in vitro and facilitates their aggregation into higher-order structures. Efficient intracellular uptake of SP18–28 abrogates CtIP localization to damaged chromatin, impairs DSB repair, and triggers extensive fork degradation. Moreover, prolonged SP18–28 treatment causes hypersensitivity to DNA-damaging agents and selectively reduces the viability of BRCA1-mutated cancer cell lines. Together, our data provide a basis for the future development of CtIP-targeting compounds with the potential to treat patients with cancer.

Download Full-text

Identification of the uvrD gene product of Escherichia coli as DNA helicase II and its induction by DNA-damaging agents.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)43445-4 ◽

1984 ◽

Vol 259 (3) ◽

pp. 1560-1565 ◽

Cited By ~ 10

Author(s):

K Kumura ◽

M Sekiguchi

Keyword(s):

Escherichia Coli ◽

Gene Product ◽

Dna Helicase ◽

Dna Helicase Ii ◽

Dna Damaging Agents

Download Full-text

Clinical outcome of breast cancer in carriers of BRCA1 and BRCA2 mutations according to molecular subtypes

Scientific Reports ◽

10.1038/s41598-020-63759-1 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 4

Author(s):

Solene De Talhouet ◽

Julien Peron ◽

Aurelie Vuilleumier ◽

Alex Friedlaender ◽

Valeria Viassolo ◽

...

Keyword(s):

Breast Cancer ◽

Disease Free Survival ◽

Germline Mutations ◽

Brca1 And Brca2 ◽

Free Survival ◽

Entire Cohort ◽

Dna Damaging Agents ◽

Impact On Survival ◽

Brca1 Brca2 ◽

Brca1 And Brca2 Mutations

Abstract BRCA1/BRCA2 genes play a central role in DNA repair and their mutations increase sensitivity to DNA-damaging agents. There are conflicting data regarding the prognostic value of BRCA germline mutations in breast cancer (BC) patients. We collected clinical, pathological and genetic data of a cohort 925 BC patients preselected for genetic screening and treated with neoadjuvant or adjuvant chemotherapy, of whom 266 were BRCA carriers. Overall, 171 women carried a BRCA1 mutation, 95 carried a BRCA2 mutation, and 659 were non-carriers. In the entire cohort, there was a prolonged disease-free survival (DFS) for BRCA carriers (hazard ratio (HR) = 0.63; 95% confidence interval (CI), 0.44–0.90 for BRCA1; HR = 0.72; 95%CI, 0.47–1.1 for BRCA2; p = 0.020) and a trend toward prolonged disease-specific survival (DSS; HR = 0.65; 95%CI, 0.40–1.1 for BRCA1; HR = 0.78; 95%CI, 0.44–1.38 for BRCA2; p = 0.19) though not statistically significant. In the TNBC group, BRCA carriers had prolonged DFS (adjusted HR = 0.50; 95%CI, 0.28–0.89 for BRCA1; adjusted HR = 0.37; 95%CI, 0.11–1.25, for BRCA2; p = 0.034) and DSS (adjusted HR = 0.42; 95%CI, 0.21–0.82 for BRCA1; adjusted HR = 0.45; 95%CI, 0.11–1.9 for BRCA2; p = 0.023). In the non-TNBC group, the BRCA1 or BRCA2 mutations did not have any impact on survival. These results suggest that BRCA1/BRCA2 germline mutations are associated with prolonged survival only if women were diagnosed with TNBC.

Download Full-text