scholarly journals Lingering single-strand breaks trigger Rad51-independent homology-directed repair of collapsed replication forks in polynucleotide kinase/phosphatase mutant of fission yeast

2017 ◽  
Author(s):  
Arancha Sanchez ◽  
Mariana C. Gadaleta ◽  
Oliver Limbo ◽  
Paul Russell
Keyword(s):  
Dna Repair ◽  
Sister Chromatid ◽  
Neurological Disease ◽  
Single Strand ◽  
Replication Forks ◽  
Strand Breaks ◽  
Homology Directed Repair ◽  
Single Strand Breaks ◽  
Polynucleotide Kinase ◽  
Sister Chromatid Recombination

ABSTRACTThe DNA repair enzyme polynucleotide kinase/phosphatase (PNKP) protects genome integrity by restoring ligatable 5’-phosphate and 3’-hydroxyl termini at single-strand breaks (SSBs). In humans, PNKP mutations underlie the neurological disease known as MCSZ, but these individuals are not predisposed for cancer, implying effective alternative repair pathways in dividing cells. Homology-directed repair (HDR) of collapsed replication forks was proposed to repair SSBs in PNKP-deficient cells, but the critical HDR protein Rad51 is not required in PNKP-null (pnk1Δ) cells of Schizosaccharomyces pombe. Here, we report that pnk1Δ cells have enhanced requirements for Rad3 (ATR/Mec1) and Chk1 checkpoint kinases, and the multi-BRCT domain protein Brc1 that binds phospho-histone H2A (γH2A) at damaged replication forks. The viability of pnk1Δ cells depends on Mre11 and Ctp1 (CtIP/Sae2) double-strand break (DSB) resection proteins, Rad52 DNA strand annealing protein, Mus81-Eme1 Holliday junction resolvase, and Rqh1 (BLM/WRN/Sgs1) DNA helicase. Eliminating Pnk1 strongly sensitizes mre11Δ pku80Δ cells to DNA damaging agents that collapse replication forks, indicating a requirement for Mre11-Rad50-Nbs1 (MRN) protein complex that cannot be efficiently replaced by Exo1 5’-3’ exonuclease. Coupled with increased sister chromatid recombination and Rad52 repair foci in pnk1Δ cells, these findings indicate that lingering SSBs in pnk1Δ cells trigger Rad51-independent homology-directed repair of collapsed replication forks.AUTHOR SUMMARYDNA is constantly damaged by normal cellular metabolism, for example production of reactive oxygen species, or from exposure to external DNA damaging sources, such as radiation from the sun or chemicals in the environment. These genotoxic agents create thousands of single-strand breaks/cell/day in the human body. An essential DNA repair protein known as polynucleotide kinase/phosphatase (PNKP) makes sure the single-strand breaks have 5’ phosphate and 3’ hydroxyl ends suitable for healing by DNA ligase. Mutations that reduce PNKP activity cause a devastating neurological disease but surprisingly not cancer, suggesting that other DNA repair mechanisms step into the breach in dividing PNKP-deficient cells. One popular candidate was homology-directed repair (HDR) of replication forks that collapse at single-strand breaks, but the crucial HDR protein Rad51 was found to be non-essential in PNKP-deficient cells of fission yeast. In this study, Sanchez and Russell revive the HDR model by showing that SSBs in PNKP-deficient cells are repaired by a variant HDR mechanism that bypasses the requirement for Rad51. Notably, Mus81 endonuclease that resolves sister chromatid recombination structures formed during HDR of collapsed replication forks was found to be essential in PNKP-deficient cells.

scholarly journals Cytogenetic markers, DNA single-strand breaks, urinary metabolites, and DNA repair rates in styrene-exposed lamination workers.

2004 ◽  
Vol 112 (8) ◽  
pp. 867-871 ◽  
Author(s):  
Pavel Vodicka ◽  
Jarno Tuimala ◽  
Rudolf Stetina ◽  
Rajiv Kumar ◽  
Paola Manini ◽  
...  
Keyword(s):  
Dna Repair ◽  
Urinary Metabolites ◽  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks

scholarly journals A CAF-1–PCNA-Mediated Chromatin Assembly Pathway Triggered by Sensing DNA Damage

2000 ◽  
Vol 20 (4) ◽  
pp. 1206-1218 ◽  
Author(s):  
Jonathan G. Moggs ◽  
Paola Grandi ◽  
Jean-Pierre Quivy ◽  
Zophonías O. Jónsson ◽  
Ulrich Hübscher ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Single Strand ◽  
Chromatin Assembly ◽  
Checkpoint Control ◽  
Free System ◽  
Strand Breaks ◽  
Assembly Pathway ◽  
Single Strand Breaks ◽  
Damaged Dna

ABSTRACT Sensing DNA damage is crucial for the maintenance of genomic integrity and cell cycle progression. The participation of chromatin in these events is becoming of increasing interest. We show that the presence of single-strand breaks and gaps, formed either directly or during DNA damage processing, can trigger the propagation of nucleosomal arrays. This nucleosome assembly pathway involves the histone chaperone chromatin assembly factor 1 (CAF-1). The largest subunit (p150) of this factor interacts directly with proliferating cell nuclear antigen (PCNA), and critical regions for this interaction on both proteins have been mapped. To isolate proteins specifically recruited during DNA repair, damaged DNA linked to magnetic beads was used. The binding of both PCNA and CAF-1 to this damaged DNA was dependent on the number of DNA lesions and required ATP. Chromatin assembly linked to the repair of single-strand breaks was disrupted by depletion of PCNA from a cell-free system. This defect was rescued by complementation with recombinant PCNA, arguing for role of PCNA in mediating chromatin assembly linked to DNA repair. We discuss the importance of the PCNA–CAF-1 interaction in the context of DNA damage processing and checkpoint control.

Methylated DNA Causes a Physical Block to Replication Forks Independently of Damage Signalling, O6-Methylguanine or DNA Single-Strand Breaks and Results in DNA Damage

2010 ◽  
Vol 402 (1) ◽  
pp. 70-82 ◽  
Author(s):  
Petra Groth ◽  
Simon Ausländer ◽  
Muntasir Mamun Majumder ◽  
Niklas Schultz ◽  
Fredrik Johansson ◽  
...  
Keyword(s):  
Dna Damage ◽  
Single Strand ◽  
Replication Forks ◽  
Strand Breaks ◽  
Methylated Dna ◽  
Single Strand Breaks

scholarly journals Sensitivity of fresh acute myeloid leukemia cells to etoposide: relationship with cell growth characteristics and DNA single-strand breaks

Blood ◽  
1992 ◽  
Vol 80 (5) ◽  
pp. 1307-1315
Author(s):  
M Chiron ◽  
C Demur ◽  
V Pierson ◽  
JP Jaffrezou ◽  
C Muller ◽  
...  
Keyword(s):  
Dna Repair ◽  
Acute Myeloid Leukemia ◽  
Cell Growth ◽  
Cell Population ◽  
Myeloid Leukemia ◽  
Growth Characteristics ◽  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Acute Myeloid

In this study, we evaluated the individual in vitro sensitivity of fresh acute myeloid leukemia (AML) cells to VP-16, and attempted to correlate VP-16 cytotoxicity with AML cell growth characteristics and drug-induced DNA single-strand breaks (SSB). Primary (PE1) colony inhibition assays allowed us to characterize two distinct groups of AML: group I (patients 1 through 6), which displayed sensitivity to VP- 16 similar to that of normal CFU-GM (IC90 of 20.52 +/- 2.44 micrograms/mL v 20.48 +/- 2.23 micrograms/mL after 1 hour drug exposure, respectively); and group II (patients 7 through 11), which was more sensitive to VP-16 (IC90 of 7.26 +/- 2.93 micrograms/mL, P = .004). Subsequently, groups I and II were termed normosensitive and hypersensitive, respectively. This objective VP-16 sensitivity classification, as determined by PE1, remained unaltered when assessed by secondary (PE2) colony inhibition assay (evaluating the self-renewal fraction of AML progenitors), or by cytofluorometric viability assay (evaluating the ultimately differentiated blast cell population). These findings would suggest that individual sensitivity to VP-16 of a particular cell population is maintained throughout CFU-AML differentiation. Finally, we report that sensitivity of AML cells to VP- 16 did not correlate either with cell growth characteristics or with SSB generation. Indeed, AML cell sensitivity to VP-16 appeared more closely related to DNA repair kinetics after drug removal, ie, hypersensitivity being essentially characterized by a prolonged retention of SSB during the posttreatment period. Interestingly, the established HL-60 cell line, which presented greater sensitivity to VP- 16 cytotoxicity than KG1, HEL, and K562, was also found to exhibit delayed DNA SSB repair kinetics, as compared with the other AML cell lines. These results suggest that hypersensitivity to VP-16 of some AML cells may be related to a deficient DNA-repair mechanism.

DNA single-strand breaks and DNA repair in the lymphocytes of wooden furniture workers

1998 ◽  
Vol 408 (2) ◽  
pp. 91-101 ◽  
Author(s):  
Jadwiga Palus ◽  
Elżbieta Dziubałtowska ◽  
Konrad Rydzyński
Keyword(s):  
Dna Repair ◽  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Wooden Furniture

scholarly journals Sensitivity of fresh acute myeloid leukemia cells to etoposide: relationship with cell growth characteristics and DNA single-strand breaks

Blood ◽  
1992 ◽  
Vol 80 (5) ◽  
pp. 1307-1315 ◽  
Author(s):  
M Chiron ◽  
C Demur ◽  
V Pierson ◽  
JP Jaffrezou ◽  
C Muller ◽  
...  
Keyword(s):  
Dna Repair ◽  
Acute Myeloid Leukemia ◽  
Cell Growth ◽  
Cell Population ◽  
Myeloid Leukemia ◽  
Growth Characteristics ◽  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Acute Myeloid

Abstract In this study, we evaluated the individual in vitro sensitivity of fresh acute myeloid leukemia (AML) cells to VP-16, and attempted to correlate VP-16 cytotoxicity with AML cell growth characteristics and drug-induced DNA single-strand breaks (SSB). Primary (PE1) colony inhibition assays allowed us to characterize two distinct groups of AML: group I (patients 1 through 6), which displayed sensitivity to VP- 16 similar to that of normal CFU-GM (IC90 of 20.52 +/- 2.44 micrograms/mL v 20.48 +/- 2.23 micrograms/mL after 1 hour drug exposure, respectively); and group II (patients 7 through 11), which was more sensitive to VP-16 (IC90 of 7.26 +/- 2.93 micrograms/mL, P = .004). Subsequently, groups I and II were termed normosensitive and hypersensitive, respectively. This objective VP-16 sensitivity classification, as determined by PE1, remained unaltered when assessed by secondary (PE2) colony inhibition assay (evaluating the self-renewal fraction of AML progenitors), or by cytofluorometric viability assay (evaluating the ultimately differentiated blast cell population). These findings would suggest that individual sensitivity to VP-16 of a particular cell population is maintained throughout CFU-AML differentiation. Finally, we report that sensitivity of AML cells to VP- 16 did not correlate either with cell growth characteristics or with SSB generation. Indeed, AML cell sensitivity to VP-16 appeared more closely related to DNA repair kinetics after drug removal, ie, hypersensitivity being essentially characterized by a prolonged retention of SSB during the posttreatment period. Interestingly, the established HL-60 cell line, which presented greater sensitivity to VP- 16 cytotoxicity than KG1, HEL, and K562, was also found to exhibit delayed DNA SSB repair kinetics, as compared with the other AML cell lines. These results suggest that hypersensitivity to VP-16 of some AML cells may be related to a deficient DNA-repair mechanism.

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