scholarly journals Poly(ADP-ribose) polymerase in base excision repair: always engaged, but not essential for DNA damage processing.

2003 ◽  
Vol 50 (1) ◽  
pp. 169-179 ◽  
Author(s):  
Sarah L Allinson ◽  
Irina I Dianova ◽  
Grigory L Dianov
Keyword(s):  
Dna Damage ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Deficient Mouse ◽  
Dna Breaks ◽  
Abasic Sites ◽  
Cell Extracts ◽  
Mouse Cells ◽  
Base Excision ◽  
Parp 1

Poly(ADP-ribose) polymerase (PARP-1) is an abundant nuclear protein with a high affinity for single- and double-strand DNA breaks. Its binding to strand breaks promotes catalysis of the covalent modification of nuclear proteins with poly(ADP-ribose) synthesised from NAD(+). PARP-1-knockout cells are extremely sensitive to alkylating agents, suggesting the involvement of PARP-1 in base excision repair; however, its role remains unclear. We investigated the dependence of base excision repair pathways on PARP-1 and NAD(+) using whole cell extracts derived from normal and PARP-1 deficient mouse cells and DNA substrates containing abasic sites. In normal extracts the rate of repair was highly dependent on NAD(+). We found that in the absence of NAD(+) repair was slowed down 4-6-fold after incision of the abasic site. We also established that in extracts from PARP-1 deficient mouse cells, repair of both regular and reduced abasic sites was increased with respect to normal extracts and was NAD(+)-independent, suggesting that in both short- and long-patch BER PARP-1 slows down, rather than stimulates, the repair reaction. Our data support the proposal that PARP-1 does not play a major role in catalysis of DNA damage processing via either base excision repair pathway.

scholarly journals HECTD1 promotes base excision repair in nucleosomes through chromatin remodelling

2019 ◽  
Vol 48 (3) ◽  
pp. 1301-1313 ◽  
Author(s):  
Laura Bennett ◽  
Eleanor C E T Madders ◽  
Jason L Parsons
Keyword(s):  
Dna Damage ◽  
Base Excision Repair ◽  
Genome Stability ◽  
Excision Repair ◽  
Chromatin Remodelling ◽  
Abasic Site ◽  
Cell Extracts ◽  
Base Excision ◽  
Cellular Dna

Abstract Base excision repair (BER) is the major cellular DNA repair pathway that recognises and excises damaged DNA bases to help maintain genome stability. Whilst the major enzymes and mechanisms co-ordinating BER are well known, the process of BER in chromatin where DNA is compacted with histones, remains unclear. Using reconstituted mononucleosomes containing a site-specific synthetic abasic site (tetrahydrofuran, THF), we demonstrate that the DNA damage is less efficiently incised by recombinant AP endonuclease 1 (APE1) when the DNA backbone is facing the histone core (THF-in) compared to that orientated away (THF-out). However, when utilizing HeLa whole cell extracts, the difference in incision of THF-in versus THF-out is less pronounced suggesting the presence of chromatin remodelling factors that stimulate THF accessibility to APE1. We subsequently purified an activity from HeLa cell extracts and identify this as the E3 ubiquitin ligase, HECTD1. We demonstrate that a recombinant truncated form of HECTD1 can stimulate incision of THF-in by APE1 in vitro by histone ubiquitylation, and that siRNA-mediated depletion of HECTD1 leads to deficiencies in DNA damage repair and decreased cell survival following x-ray irradiation, particularly in normal fibroblasts. Thus, we have now identified HECTD1 as an important factor in promoting BER in chromatin.

Cells Lacking the PolQ Polymerase Are Moderately Sensitive to Ionizing Radiation and the Oxidant Induced Toxicity of Paraquat and Bleomycin.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4037-4037
Author(s):  
Julie P. Goff ◽  
Michael W. Epperly ◽  
Donna S. Shields ◽  
Tracy Smith ◽  
Mineaki Seki ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Ionizing Radiation ◽  
Peripheral Blood ◽  
Excision Repair ◽  
Dna Breaks ◽  
Thymine Glycol ◽  
Abasic Sites ◽  
Significant Difference ◽  
Base Excision

Abstract The DNA polymerase POLQ (pol theta) can bypass abasic sites in DNA and thymine glycol, a common product of reactive oxygen species damage to DNA. POLQ may also have a back-up role in base excision repair. To explore the role of POLQ in tolerance of DNA damage following irradiation, and exposure to agents that induce oxidative stress we established bone marrow stromal cell lines from the PolQ+/+ and PolQ−/− mice. Irradiation survival curves were obtained for PolQ +/+, and 2 clones of PolQ −/− cells. Dose-response experiments using the free radical generators paraquat, hydrogen peroxide and bleomycin were done on 2 clones each of PolQ +/+ and PolQ −/− cells. There was no significant difference over 23 weeks in cumulative granulopoiesis in LTBMCs from PolQ +/+ and PolQ −/− mice. PolQ+/+ cells and 2 independent clones of PolQ−/− cells were exposed to 0 – 8 Gy of gamma radiation, and colony forming ability was measured. PolQ −/− cells were more sensitive to irradiation as shown by decreased Do from 1.38 + 0.06 Gy for PolQ +/+ cells compared to 1.27 + 0.16 and 0.98 + 0.10 (p = 0.0316) Gy for PolQ −/− clones 1 and 3 respectively. Micronucleated reticulocytes were measured in peripheral blood of PolQ+/+, +/− or −/− mice after irradiation with 75 cGy or 700 cGy. Before irradiation, PolQ−/− mice had a higher fraction of MN- reticulocytes compared to PolQ+/+. Forty hr after irradiation, MN reticulocytes in PolQ−/− mice increased to 8.53 ± 1.48%, compared to 2.35 ± 0.12% and 2.55 ± 0.17% in PolQ+/+ mice (p = 0.0032). PolQ +/+ and PolQ −/− cells were exposed to paraquat (0–20 mM), hydrogen peroxide (0–40 uM) and bleomycin (0–5 ug/ml) for 1 hr prior to plating. After 7 days, the cells were stained and colonies of 50 cells or greater were counted. Statistical analysis was done using ANCOVA. PolQ −/− cells were modestly more sensitive to paraquat (p< 0.0001) and bleomycin (p< 0.0001) than PolQ +/+ cells. When the cells were treated with hydrogen peroxide, there was no significant difference in surviving fraction (p=0.7327) between the PolQ +/+ and the −/− cells. The moderate but significant sensitivity of POLQ-defective cells to bleomycin, ionizing radiation and paraquat supports the hypothesis that POLQ normally participates in helping cells tolerate DNA damage. The increased frequencies of spontaneous and radiation-induced micronuclei in peripheral blood red cells indicate that POLQ has a role in maintaining genomic integrity via limiting double-strand DNA breaks.

A new DNA breaks repair pathway involving PARP3 and base excision repair proteins

2018 ◽  
Vol 482 (1) ◽  
pp. 96-100
Author(s):  
E. Belousova ◽  
◽  
M. Kutuzov ◽  
P. Ivankina ◽  
A. Ishchenko ◽  
...  
Keyword(s):  
Base Excision Repair ◽  
Excision Repair ◽  
Repair Pathway ◽  
Dna Breaks ◽  
Base Excision

scholarly journals Base excision repair causes age-dependent accumulation of single-stranded DNA breaks that contribute to Parkinson disease pathology

Cell Reports ◽  
2021 ◽  
Vol 36 (10) ◽  
pp. 109668
Author(s):  
Tanima SenGupta ◽  
Konstantinos Palikaras ◽  
Ying Q. Esbensen ◽  
Georgios Konstantinidis ◽  
Francisco Jose Naranjo Galindo ◽  
...  
Keyword(s):  
Parkinson Disease ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Dna Breaks ◽  
Single Stranded Dna ◽  
Age Dependent ◽  
Base Excision
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