Telomerase Is Essential to Alleviate Pif1-Induced Replication Stress at Telomeres

Chang, Michael; Luke, Brian; Kraft, Claudine; Z, Li; Peter, Matthias; Lingner, Joachim; Rothstein, Rodney

doi:10.1534/genetics.109.107631

Cited by 30 publications

(43 citation statements)

References 115 publications

(151 reference statements)

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“…Such backtracked forks will expose single-stranded leading strand TG (1-3) repeat sequence DNA, which is the substrate for telomerase elongation. Also, telomerase could aid in the repair of a broken telomeric fork generated when a stalled replisome collapses (Chang et al, 2009). The resulting shortened telomere is a known preferred telomerase substrate (Miller et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Early Telomerase Inactivation Accelerates Aging Independently of Telomere Length

Xie

Jay

Smith

et al. 2015

Cell

108

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SUMMRAY Telomerase is required for long-term telomere maintenance and protection. Using single budding yeast mother cell analyses we found that, even Early after Telomerase Inactivation (ETI), yeast mother cells show transient DNA Damage Response (DDR) episodes, stochastically altered cell cycle dynamics, and accelerated mother cell aging. The acceleration of ETI mother cell aging was not explained by increased reactive oxygen species (ROS), Sir protein perturbation, or deprotected telomeres. ETI occurred well before the population senescence and caused late after telomerase inactivation (LTI). ETI phenotypes were morphologically distinct from LTI senescence, genetically uncoupled from telomere length, and were rescued by elevating dNTP pools. Our combined genetic and single-cell analyses show that well before critical telomere shortening, telomerase is continuously required to respond to transient DNA replication stress in mother cells, and that a lack of telomerase accelerates otherwise normal aging.

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Section: Discussionmentioning

confidence: 99%

Early Telomerase Inactivation Accelerates Aging Independently of Telomere Length

Xie

Jay

Smith

et al. 2015

Cell

108

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“…Scans were performed using a custom mask with openings for nine rectangular plates to eliminate reflection anomalies. The SGA protocol was performed as described (Chang et al 2009), except that during the final selection, replica-pin copies were made to plates containing 100 mM CuSO 4 to induce expression of the plasmid-borne TOP1 alleles.…”

Section: Yeast Strains and Methodsmentioning

confidence: 99%

Selective ploidy ablation, a high-throughput plasmid transfer protocol, identifies new genes affecting topoisomerase I–induced DNA damage

et al. 2010

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We have streamlined the process of transferring plasmids into any yeast strain library by developing a novel mating-based, high-throughput method called selective ploidy ablation (SPA). SPA uses a universal plasmid donor strain that contains conditional centromeres on every chromosome. The plasmid-bearing donor is mated to a recipient, followed by removal of all donor-strain chromosomes, producing a haploid strain containing the transferred plasmid. As proof of principle, we used SPA to transfer plasmids containing wild-type and mutant alleles of DNA topoisomerase I (TOP1) into the haploid yeast genedisruption library. Overexpression of Top1 identified only one sensitive mutation, rpa34, while overexpression of top1-T 722 A allele, a camptothecin mimetic, identified 190 sensitive gene-disruption strains along with rpa34. In addition to known camptothecin-sensitive strains, this set contained mutations in genes involved in the Rpd3 histone deacetylase complex, the kinetochore, and vesicle trafficking. We further show that mutations in several ESCRT vesicle trafficking components increase Top1 levels, which is dependent on SUMO modification. These findings demonstrate the utility of the SPA technique to introduce plasmids into the haploid gene-disruption library to discover new interacting pathways.

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“…Pif1 is implicated in replisome stability, processing of G-quadruplexes, telomerase regulation, and Okazaki fragment processing (Zhou et al 2000;Chang et al 2009;Pike et al 2009;Ribeyre et al 2009;Lopes et al 2011;Paeschke et al 2011). While the Pif1 helicase appears not to contribute to resection at DSBs, it has a critical role in the resection of uncapped telomeres in cdc13-1 mutants (Fig.…”

Section: The Cst Complexmentioning

confidence: 99%

“…A second possibility is that Pif1 promotes the DDR by processing a substrate present at uncapped telomeres but not DSBs. Indeed, Pif1 appears to affect replisome instability and to promote replication fork progression under conditions of replication stress, suggesting it might initiate a replicationdependent DDR (Paeschke et al 2011;Chang et al 2009;Lopes et al 2011). However, although Pif1 does not affect resection at DSBs, it is required to prevent high levels of chromosome loss occurring following induction of a DSB near a chromosome end, demonstrating that it clearly does have some role at DSBs .…”

Section: The Cst Complexmentioning

confidence: 99%

“…While Pif1 has no role in the resection of DSBs, it appears to be important for resection following inactivation of yCST Dewar and Lydall 2010). Furthermore, Pif1 has roles in DNA replication and recognizes 5′ ssDNA, which could occur at replication forks but not at a native 3′ telomeric overhangs (Chang et al 2009;Pike et al 2009;Paeschke et al 2011). Thus, a role for Pif1 in the DDR following inactivation of yCST would be consistent with a role for yCST in facilitating DNA replication.…”

Section: Evidence For a Replication-associated Ddr At Uncapped Telomeresmentioning

confidence: 99%

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Similarities and differences between “uncapped” telomeres and DNA double-strand breaks

Dewar

Lydall

2011

Chromosoma

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Telomeric DNA is present at the ends of eukaryotic chromosomes and is bound by telomere "capping" proteins, which are the (Cdc13-Stn1-Ten1) CST complex, Ku (Yku70-Yku80), and Rap1-Rif1-Rif2 in budding yeast. Inactivation of any of these complexes causes telomere "uncapping," stimulating a DNA damage response (DDR) that frequently involves resection of telomeric DNA and stimulates cell cycle arrest. This is presumed to occur because telomeres resemble one half of a DNA double-strand break (DSB). In this review, we outline the DDR that occurs at DSBs and compare it to the DDR occurring at uncapped telomeres, in both budding yeast and metazoans. We give particular attention to the resection of DSBs in budding yeast by Mre11-Xrs2-Rad50 (MRX), Sgs1/Dna2, and Exo1 and compare their roles at DSBs and uncapped telomeres. We also discuss how resection uncapped telomeres in budding yeast is promoted by the by 9-1-1 complex (Rad17-Mec3-Ddc1), to illustrate how analysis of uncapped telomeres can serve as a model for the DDR elsewhere in the genome. Finally, we discuss the role of the helicase Pif1 and its requirement for resection of uncapped telomeres, but not DSBs. Pif1 has roles in DNA replication and mammalian and plant CST complexes have been identified and have roles in global genome replication. Based on these observations, we suggest that while the DDR at uncapped telomeres is partially due to their resemblance to a DSB, it may also be partially due to defective DNA replication. Specifically, we propose that the budding yeast CST complex has dual roles to inhibit a DSB-like DDR initiated by Exo1 and a replication-associated DDR initiated by Pif1. If true, this would suggest that the mammalian CST complex inhibits a Pif1-dependent DDR.

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Telomerase Is Essential to Alleviate Pif1-Induced Replication Stress at Telomeres

Cited by 30 publications

References 115 publications

Early Telomerase Inactivation Accelerates Aging Independently of Telomere Length

Early Telomerase Inactivation Accelerates Aging Independently of Telomere Length

Selective ploidy ablation, a high-throughput plasmid transfer protocol, identifies new genes affecting topoisomerase I–induced DNA damage

Similarities and differences between “uncapped” telomeres and DNA double-strand breaks

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