DNA repair efficiency and thermotolerance in Drosophila melanogaster from 'Evolution Canyon'

Genetic polymorphisms in DNA repair genes may affect DNA repair efficiency and may contribute to the risk of developing cancer. The aim of our study was to investigate single nucleotide polymorphisms (SNPs) in RAD51 (rs2619679, rs2928140, and rs5030789) and XRCC3 (rs1799796) involved in DNA double-strand break repair and their relationship to prostate cancer. The study group included 99 men diagnosed with prostate cancer and 205 cancer-free controls. SNP genotyping was performed using the PCR-RFLP method. A significant association was detected between RAD51 rs5030789 polymorphism and XRCC3 rs1799796 polymorphism and an increased risk of prostate cancer. Our results indicate that RAD51 and XRCC3 polymorphism may contribute to prostate cancer.

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Increased Sensitivity of PBMCs Isolated from Patients with Rheumatoid Arthritis to DNA Damaging Agents Is Connected with Inefficient DNA Repair

Journal of Clinical Medicine ◽

10.3390/jcm9040988 ◽

2020 ◽

Vol 9 (4) ◽

pp. 988

Author(s):

Grzegorz Galita ◽

Olga Brzezińska ◽

Izabela Gulbas ◽

Joanna Sarnik ◽

Marta Poplawska ◽

...

Keyword(s):

Rheumatoid Arthritis ◽

Dna Repair ◽

Mononuclear Cells ◽

Excision Repair ◽

Dna Lesions ◽

Dna Breaks ◽

Peripheral Blood Mononuclear ◽

Dna Damaging Agents ◽

Repair Efficiency ◽

Systemic Inflammatory Disease

Rheumatoid arthritis (RA) is a systemic, inflammatory disease of the joints and surrounding tissues. RA manifests itself with severe joint pain, articular inflammation, and oxidative stress. RA is associated with certain types of cancer. We have assumed that RA patients’ increased susceptibility to cancer may be linked with genomic instability induced by impaired DNA repair and sensitivity to DNA damaging agents. The aim of this work was to analyze the sensitivity of peripheral blood mononuclear cells (PBMCs) isolated from RA patients to DNA damaging agents: tert-butyl hydroperoxide (TBH), bleomycin, ultraviolet (UV) radiation, and methyl methanesulfonate (MMS) and calculate the repair efficiency. TBH induce oxidative DNA lesions repaired mainly by base excision repair (BER). Bleomycin induced mainly DNA double-strand breaks repaired by non-homologous end joining (NHEJ) and homologous recombination repair (HRR). We included 20 rheumatoid arthritis patients and 20 healthy controls and used an alkaline version of the comet assay with modification to measure sensitivity to DNA damaging agents and DNA repair efficiency. We found an increased number of DNA breaks and alkali-labile sites in the RA patients compared to those in the controls. Exposure to DNA damaging agents evoked the same increased damage in both groups, but we observed statistically higher PMBC sensitivity to TBH, MMS, bleomycin as well as UV. Examination of the repair kinetics of both groups revealed that the DNA lesions induced by TBH and bleomycin were more efficiently repaired in the controls than in the patients. These data suggest impaired DNA repair in RA patients, which may accelerate PBMC aging and/or lead to higher cancer incidence among RA patients.

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The Drosophila melanogaster Ortholog of RFWD3 Functions Independently of RAD51 During DNA Repair

G3 Genes|Genome|Genetics ◽

10.1534/g3.119.400903 ◽

2020 ◽

Vol 10 (3) ◽

pp. 999-1004

Author(s):

Juan Carvajal-Garcia ◽

Evan R. Gales ◽

Dale A. Ramsden ◽

Jeff Sekelsky

Keyword(s):

Dna Repair ◽

Drosophila Melanogaster ◽

Ring Finger ◽

Double Strand Breaks ◽

Specific Gene ◽

Genetic Screens ◽

Strand Breaks ◽

Ancestral Function ◽

Human Ortholog

Repair of damaged DNA is required for the viability of all organisms. Studies in Drosophila melanogaster, driven by the power of genetic screens, pioneered the discovery and characterization of many genes and pathways involved in DNA repair in animals. However, fewer than half of the alleles identified in these screens have been mapped to a specific gene, leaving a potential for new discoveries in this field. Here we show that the previously uncharacterized mutagen sensitive gene mus302 codes for the Drosophila melanogaster ortholog of the E3 ubiquitin ligase RING finger and WD domain protein 3 (RFWD3). In human cells, RFWD3 promotes ubiquitylation of RPA and RAD51 to facilitate repair of collapsed replication forks and double-strand breaks through homologous recombination. Despite the high similarity in sequence to the human ortholog, our evidence fails to support a role for Mus302 in the repair of these types of damage. Last, we observe that the N-terminal third of RFWD3 is only found in mammals, but not in other vertebrates or invertebrates. We propose that the new N-terminal sequence accounts for the acquisition of a new biological function in mammals that explains the functional differences between the human and the fly orthologs, and that Drosophila Mus302 may retain the ancestral function of the protein.

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