Cell cycle–dependent spatial segregation of telomerase from sites of DNA damage

Ouenzar, Faissal; Lalonde, Maxime; Laprade, Hadrien; Morin, Geneviève; Gallardo, Franck; Tremblay‐Belzile, Samuel; Chartrand, Pascal

doi:10.1083/jcb.201610071

Cited by 13 publications

(26 citation statements)

References 72 publications

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“…damage-induced foci is reduced [26,46]. However, while we observe that rad52Δ is epistatic to rad51Δ for de novo telomere addition (Fig 1B), the TLC1 RNA localization phenotype of the rad51Δ strain is epistatic to that observed upon loss of RAD52 [46].…”

Section: Discussionmentioning

confidence: 58%

“…Rad52 enforces nucleolar localization, which may sequester telomerase from double-strand breaks. In contrast to cells lacking Rad52 function, which display increased nucleoplasmic localization of TLC1 after DNA damage, cells lacking RAD51 show little relocalization of TLC1 RNA to the nucleoplasm [46] and association of Cdc13 with DNA Because the GCR frequency of the rfa1-44 strain is significantly higher than WT on both chromosomes 5 and 9, the absolute GCR frequency in each region of chromosome 9 (C) or 5 (D) is shown from the same experiments as panel A. Values are averages from three independent experiments with standard deviation.…”

Section: Discussionmentioning

confidence: 71%

“…The Chartrand group has reported that that the intranuclear trafficking of the telomerase (TLC1) RNA is modulated in G2/M phase in response to DNA damage [46]. While TLC1 RNA is predominantly nucleolar in G2/M, nucleoplasmic localization increases moderately in response to DNA damage [46]. Rad52 enforces nucleolar localization, which may sequester telomerase from double-strand breaks.…”

Section: Discussionmentioning

confidence: 99%

“…Both chromatin immunoprecipitation (ChIP) and immunofluorescence studies show that the association of Cdc13 with DNA (following HO-or chemically-induced DSBs) is stimulated by Rad51 [26,46]. We previously observed that high levels of de novo telomere addition at SiRTAs correlates with the ability of the SiRTA-stim sequence to bind Cdc13 and that the effect of the stim sequence is mimicked by artificial recruitment of Cdc13 [20].…”

Section: In the Absence Of Rad51 Rad52 Reduces Recruitment Of Cdc13 mentioning

confidence: 99%

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Interaction of yeast Rad51 and Rad52 relieves Rad52-mediated inhibition of de novo telomere addition

2020

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DNA double-strand breaks (DSBs) are toxic forms of DNA damage that must be repaired to maintain genome integrity. Telomerase can act upon a DSB to create a de novo telomere, a process that interferes with normal repair and creates terminal deletions. We previously identified sequences in Saccharomyces cerevisiae (SiRTAs; Sites of Repairassociated Telomere Addition) that undergo unusually high frequencies of de novo telomere addition, even when the original chromosome break is several kilobases distal to the eventual site of telomerase action. Association of the single-stranded telomere binding protein Cdc13 with a SiRTA is required to stimulate de novo telomere addition. Because extensive resection must occur prior to Cdc13 binding, we utilized these sites to monitor the effect of proteins involved in homologous recombination. We find that telomere addition is significantly reduced in the absence of the Rad51 recombinase, while loss of Rad52, required for Rad51 nucleoprotein filament formation, has no effect. Deletion of RAD52 suppresses the defect of the rad51Δ strain, suggesting that Rad52 inhibits de novo telomere addition in the absence of Rad51. The ability of Rad51 to counteract this effect of Rad52 does not require DNA binding by Rad51, but does require interaction between the two proteins, while the inhibitory effect of Rad52 depends on its interaction with Replication Protein A (RPA). Intriguingly, the genetic interactions we report between RAD51 and RAD52 are similar to those previously observed in the context of checkpoint adaptation. Forced recruitment of Cdc13 fully restores telomere addition in the absence of Rad51, suggesting that Rad52, through its interaction with RPA-coated single-stranded DNA, inhibits the ability of Cdc13 to bind and stimulate telomere addition. Loss of the Rad51-Rad52 interaction also stimulates a subset of Rad52-dependent microhomology-mediated repair (MHMR) events, consistent with the known ability of Rad51 to prevent single-strand annealing.

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Section: Discussionmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Section: In the Absence Of Rad51 Rad52 Reduces Recruitment Of Cdc13 mentioning

confidence: 99%

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Interaction of yeast Rad51 and Rad52 relieves Rad52-mediated inhibition of de novo telomere addition

2020

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“…ScPif1 removes telomerase by interacting directly with the finger domain of the telomerase subunit Est2 [136]. Recently, ScPif1 was found to regulate telomere elongation by affecting the spatial distribution of telomerase components by segregating the limiting component of telomerase, the RNA TLC1, to the nucleolus [44]. While it is known how ScPif1 removes telomerase from telomere DNA, the mechanism of sequestering it to the nucleolus remains to be identified.…”

Section: Telomere Length Maintenancementioning

confidence: 99%

Yeast Genome Maintenance by the Multifunctional PIF1 DNA Helicase Family

Muellner

Schmidt

2020

Genes

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The two PIF1 family helicases in Saccharomyces cerevisiae, Rrm3, and ScPif1, associate with thousands of sites throughout the genome where they perform overlapping and distinct roles in telomere length maintenance, replication through non-histone proteins and G4 structures, lagging strand replication, replication fork convergence, the repair of DNA double-strand break ends, and transposable element mobility. ScPif1 and its fission yeast homolog Pfh1 also localize to mitochondria where they protect mitochondrial genome integrity. In addition to yeast serving as a model system for the rapid functional evaluation of human Pif1 variants, yeast cells lacking Rrm3 have proven useful for elucidating the cellular response to replication fork pausing at endogenous sites. Here, we review the increasingly important cellular functions of the yeast PIF1 helicases in maintaining genome integrity, and highlight recent advances in our understanding of their roles in facilitating fork progression through replisome barriers, their functional interactions with DNA repair, and replication stress response pathways.

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Emerging non-canonical roles for the Rad51–Rad52 interaction in response to double-strand breaks in yeast

Ngo

Friedman

2020

Curr Genet

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DNA double-strand break repair allows cells to survive both exogenous and endogenous insults to the genome. In yeast, the recombinases Rad51 and Rad52 are central to multiple forms of homology-dependent repair. Classically, Rad51 and Rad52 are thought to act cooperatively, with formation of the functional Rad51 nucleofilament facilitated by the mediator function of Rad52. Several studies have now identified functions for the interaction between Rad51 and Rad52 that are independent of the mediator function of Rad52 and affect a seemingly diverse array of functions in de novo telomere addition, global chromosome mobility following DNA damage, Rad51 nucleofilament stability, checkpoint adaptation, and microhomology-mediated chromosome rearrangements. Here, we review these functions with an emphasis on our recent discovery that the Rad51-Rad52 interaction influences the probability of de novo telomere addition at sites preferentially targeted by telomerase following a double-strand break (DSB). We present data addressing the prevalence of sites within the yeast genome that are capable of stimulating de novo telomere addition following a DSB and speculate about the potential role such sites may play in genome stability.

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Cell cycle–dependent spatial segregation of telomerase from sites of DNA damage

Abstract: Telomerase can generate a novel telomere at a DNA break, with potentially lethal consequences for the cell. Ouenzar et al. reveal novel roles for Pif1, Rad52, and Siz1-dependent sumoylation in the spatial exclusion of telomerase from sites of DNA repair during the cell cycle.

Cited by 13 publications

References 72 publications

Interaction of yeast Rad51 and Rad52 relieves Rad52-mediated inhibition of de novo telomere addition

Interaction of yeast Rad51 and Rad52 relieves Rad52-mediated inhibition of de novo telomere addition

Yeast Genome Maintenance by the Multifunctional PIF1 DNA Helicase Family

Emerging non-canonical roles for the Rad51–Rad52 interaction in response to double-strand breaks in yeast

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