Human Rad51C Deficiency Destabilizes XRCC3, Impairs Recombination, and Radiosensitizes S/G2-phase Cells

Lio, Yi Ching; Schild, David; Brenneman, Mark A.; Redpath, J. L.; Chen, David J.

doi:10.1074/jbc.m405212200

Cited by 64 publications

(72 citation statements)

References 68 publications

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“…Previous studies also suggest that the stability of other Rad51 paralog proteins is dependent on Rad51C (60). We found that depletion of Rad51C led to a significant reduction in cellular levels of Xrcc3, as was observed previously (60), yet levels of Rad51B, Rad51D, and Xrcc2 remained unaffected (supplemental Fig. 3A).…”

Section: Dna Damage-induced Nuclear Transport Of Rad51 Involves Both supporting

confidence: 88%

Cellular Redistribution of Rad51 in Response to DNA Damage

Gildemeister

Sage

Knight

2009

Journal of Biological Chemistry

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Exposure of cells to DNA-damaging agents results in a rapid increase in the formation of subnuclear complexes containing Rad51. To date, it has not been determined to what extent DNA damage-induced cytoplasmic to nuclear transport of Rad51 may contribute to this process. We have analyzed subcellular fractions of HeLa and HCT116 cells and found a significant increase in nuclear Rad51 levels following exposure to a modest dose of ionizing radiation (2 grays). We also observed a DNA damageinduced increase in nuclear Rad51 in the Brca2-defective cell line Capan-1. To address a possible Brca2-independent mechanism for Rad51 nuclear transport, we analyzed subcellular fractions for two other Rad51-interacting proteins, Rad51C and Xrcc3. Rad51C has a functional nuclear localization signal, and although we found that the subcellular distribution of Xrcc3 was not significantly affected by DNA damage, there was a damageinduced increase in nuclear Rad51C. Furthermore, RNA interference-mediated depletion of Rad51C in HeLa and Capan-1 cells resulted in lower steady-state levels of nuclear Rad51 as well as a diminished DNA damage-induced increase. Our results provide important insight into the cellular regulation of Rad51 nuclear entry and a role for Rad51C in this process.Cellular surveillance of genome integrity and repair of DNA damage are essential processes that ensure proper development and survival of all organisms. DNA double-strand breaks (DSBs) 2 are a particularly deleterious form of genome damage and occur following exposure of cells to exogenous mutagens as well as during normal metabolic processes, e.g. antigen receptor gene rearrangement, restart of stalled replication forks, formation of meiotic DNA crossovers, etc. (1, 2). Mammalian cells use two distinct mechanisms for repair of DSBs, non-homologous end joining and homologous recombination (HR). Processes requiring imprecise DNA repair, such as the creation of antibody diversity, exploit the error-prone non-homologous end joining mechanism. In contrast, HR is an error-free DNA repair pathway and is critical for avoidance of unwanted genetic changes during the meiotic exchange of information between paternal and maternal alleles and for error-free repair of broken chromosomes (3). Rad51 is the central enzymatic component of HR. Upon its regulated recruitment to sites of DNA breaks, Rad51 forms a nucleoprotein filament by polymerizing onto single-stranded DNA at the processed break. This filament catalyzes DNA strand exchange with an undamaged sister chromatid or homologous chromosome, which serves as a template for the restoration of missing genetic information (3, 4).Visible nuclear Rad51 clusters, or foci, form during S-phase and appear to localize to sites of replicating DNA (5-7). A dramatic increase in the number and size of nuclear Rad51 foci is a hallmark of the early cellular response to genomic insult (7-10). The appearance of DNA damage-induced nuclear Rad51 foci is blocked in cells with deficiencies in several HR-related proteins, including Brca2 ...

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Section: Dna Damage-induced Nuclear Transport Of Rad51 Involves Both supporting

confidence: 88%

Cellular Redistribution of Rad51 in Response to DNA Damage

Gildemeister

Sage

Knight

2009

Journal of Biological Chemistry

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“…Previous studies of mammals suggested that Rad51 paralogs form two complexes, BCDX2 and CX3, both containing Rad51C (Miller et al, 2004). Moreover, Lio et al (2004) reported that inhibition of Rad51C reduced the protein levels of Xrcc3 and Rad51B in four other Rad51 paralogs, although the reduction of Rad51B was less and more transient. Thus, it is thought that Rad51C is a central component of Rad51 paralog complexes and that it may regulate the amount of Rad51 paralog complexes.…”

Section: Discussionmentioning

confidence: 94%

Arabidopsis RAD51C Gene Is Important for Homologous Recombination in Meiosis and Mitosis

et al. 2005

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Rad51 is a homolog of the bacterial RecA recombinase, and a key factor in homologous recombination in eukaryotes. Rad51 paralogs have been identified from yeast to vertebrates. Rad51 paralogs are thought to play an important role in the assembly or stabilization of Rad51 that promotes homologous pairing and strand exchange reactions. We previously characterized two RAD51 paralogous genes in Arabidopsis (Arabidopsis thaliana) named AtRAD51C and AtXRCC3, which are homologs of human RAD51C and XRCC3, respectively, and described the interaction of their products in a yeast two-hybrid system. Recent studies showed the involvement of AtXrcc3 in DNA repair and functional role in meiosis. To determine the role of RAD51C in meiotic and mitotic recombination in higher plants, we characterized a T-DNA insertion mutant of AtRAD51C. Although the atrad51C mutant grew normally during vegetative developmental stage, the mutant produced aborted siliques, and their anthers did not contain mature pollen grains. Crossing of the mutant with wild-type plants showed defective male and female gametogeneses as evidenced by lack of seed production. Furthermore, meiosis was severely disturbed in the mutant. The atrad51C mutant also showed increased sensitivity to g-irradiation and cisplatin, which are known to induce double-strand DNA breaks. The efficiency of homologous recombination in somatic cells in the mutant was markedly reduced relative to that in wild-type plants.

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“…Moreover, spontaneous sister chromatid exchange (SCE), which is mainly mediated by HR (Sonoda et al , 1999), was similar between WT and SirT7 −/− cells (Appendix Fig S7C–E). We used a HR reporter locus stably integrated in HT1080 cells (Lio et al , 2004). This HR assay is based on the recovery of a puromycin resistance gene after successful repair of an I‐SceI‐induced DSB.…”

Section: Resultsmentioning

confidence: 99%

SIRT 7 promotes genome integrity and modulates non‐homologous end joining DNA repair

et al. 2016

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Sirtuins, a family of protein deacetylases, promote cellular homeostasis by mediating communication between cells and environment. The enzymatic activity of the mammalian sirtuin SIRT7 targets acetylated lysine in the N‐terminal tail of histone H3 (H3K18Ac), thus modulating chromatin structure and transcriptional competency. SIRT7 deletion is associated with reduced lifespan in mice through unknown mechanisms. Here, we show that SirT7‐knockout mice suffer from partial embryonic lethality and a progeroid‐like phenotype. Consistently, SIRT7‐deficient cells display increased replication stress and impaired DNA repair. SIRT7 is recruited in a PARP1‐dependent manner to sites of DNA damage, where it modulates H3K18Ac levels. H3K18Ac in turn affects recruitment of the damage response factor 53BP1 to DNA double‐strand breaks (DSBs), thereby influencing the efficiency of non‐homologous end joining (NHEJ). These results reveal a direct role for SIRT7 in DSB repair and establish a functional link between SIRT7‐mediated H3K18 deacetylation and the maintenance of genome integrity.

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Human Rad51C Deficiency Destabilizes XRCC3, Impairs Recombination, and Radiosensitizes S/G2-phase Cells

Cited by 64 publications

References 68 publications

Cellular Redistribution of Rad51 in Response to DNA Damage

Cellular Redistribution of Rad51 in Response to DNA Damage

Arabidopsis RAD51C Gene Is Important for Homologous Recombination in Meiosis and Mitosis

SIRT 7 promotes genome integrity and modulates non‐homologous end joining DNA repair

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