The Histone Deacetylases Sir2 and Rpd3 Act on Ribosomal DNA to Control the Replication Program in Budding Yeast

Yoshida, Kazumasa; Bacal, Julien; Desmarais, Damien; Padioleau, Ismaël; Tsaponina, Olga; Chabes, Andrei; Pantesco, Véronique; Dubois, Emeric; Parrinello, Hugues; Skrzypczak, Magdalena; Ginalski, Krzysztof; Lengronne, Armelle; Pasero, Philippe

doi:10.1016/j.molcel.2014.04.032

Cited by 104 publications

(122 citation statements)

References 43 publications

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“…Alternatively, the hyopacetylation of H4K16 in these regions could be due to transient Sir2 association not captured by ChIP-Seq. Previous studies have shown that Sir2, but not Sir3 or Sir4, controls some origins of replication (Pappas et al 2004;Crampton et al 2008;Yoshida et al 2014). However, MACS did not detect any significant enrichment for Sir2 at subtelomeric ARSs outside the core X element.…”

Section: Catalytic Activity Of Sir2 At Telomerescontrasting

confidence: 54%

The Chromatin and Transcriptional Landscape of NativeSaccharomyces cerevisiaeTelomeres and Subtelomeric Domains

2015

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Saccharomyces cerevisiae telomeres have been a paradigm for studying telomere position effects on gene expression. Telomere position effect was first described in yeast by its effect on the expression of reporter genes inserted adjacent to truncated telomeres. The reporter genes showed variable silencing that depended on the Sir2/3/4 complex. Later studies examining subtelomeric reporter genes inserted at natural telomeres hinted that telomere position effects were less pervasive than previously thought. Additionally, more recent data using the sensitive technology of chromatin immunoprecipitation and massively parallel sequencing (ChIP-Seq) revealed a discrete and noncontinuous pattern of coenrichment for all three Sir proteins at a few telomeres, calling the generality of these conclusions into question. Here we combined the ChIP-Seq of the Sir proteins with RNA sequencing (RNA-Seq) of messenger RNAs (mRNAs) in wild-type and in SIR2, SIR3, and SIR4 deletion mutants to characterize the chromatin and transcriptional landscape of all native S. cerevisiae telomeres at the highest achievable resolution. Most S. cerevisiae chromosomes had subtelomeric genes that were expressed, with only 6% of subtelomeric genes silenced in a SIR-dependent manner. In addition, we uncovered 29 genes with previously unknown cell-type-specific patterns of expression. These detailed data provided a comprehensive assessment of the chromatin and transcriptional landscape of the subtelomeric domains of a eukaryotic genome.KEYWORDS Sir complex; telomeres; ChIP-Seq; RNA-Seq; mating-type regulation T ELOMERES are specialized structures at the ends of eukaryotic chromosomes that are critical for various biological functions. Telomeres bypass the problem of replicating the ends of linear DNA, protect chromosome ends from exonucleases and nonhomologous end joining, prevent the linear DNA ends from activating a DNA-damage checkpoint, and exhibit suppressed recombination [reviewed in Wellinger and Zakian (2012)]. In Saccharomyces cerevisiae, telomeres are composed of three sequence features: telomeric repeats, which consist of 300 6 75 bp of (TG 1-3 ) n repeated units produced by telomerase; X elements; and Y9 elements, which contain an ORF for a putative helicase gene. The X elements are subdivided into a core X [consisting of an autonomously replicating sequence (ARS) consensus sequence and an Abf1-binding site] and subtelomeric repeats that have variable numbers of repeated units containing a binding site for Tbf1 (Louis 1995). All telomeres contain telomeric repeats plus an X element, and about half of S. cerevisiae's 32 telomeres also contain a Y9 element (X-Y9 telomeres). X-only telomeres contain an X element but not a Y9 element. Unlike the Y9 elements, the telomeric repeats and X elements are bound by proteins that are critical for maintenance of telomeres. Rap1 binds the TG 1-3 telomeric repeats and recruits the Sir2/3/4 protein complex, the trio of heterochromatin structural proteins critical for repression of the silent mating ...

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Section: Catalytic Activity Of Sir2 At Telomerescontrasting

confidence: 54%

The Chromatin and Transcriptional Landscape of NativeSaccharomyces cerevisiaeTelomeres and Subtelomeric Domains

2015

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“…origin efficiency at other loci (11,12). Overall, these observations suggest that increased replication of repetitive regions of the genome can lead to replication gaps elsewhere, and that the presence of such gaps may constitute the proximal cause of death in cellular aging.…”

Section: Significancementioning

confidence: 85%

SIR2 suppresses replication gaps and genome instability by balancing replication between repetitive and unique sequences

Foss

Lao

Dalrymple

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Replication gaps that persist into mitosis likely represent important threats to genome stability, but experimental identification of these gaps has proved challenging. We have developed a technique that allows us to explore the dynamics by which genome replication is completed before mitosis. Using this approach, we demonstrate that excessive allocation of replication resources to origins within repetitive regions, induced by SIR2 deletion, leads to persistent replication gaps and genome instability. Conversely, the weakening of replication origins in repetitive regions suppresses these gaps. Given known age-and cancer-associated changes in chromatin accessibility at repetitive sequences, we suggest that replication gaps resulting from misallocation of replication resources underlie age-and disease-associated genome instability.SIR2 | DNA replication | repetitive sequences | replication gaps | ribosomal DNA S taggered initiation of DNA replication, which is common across eukaryotes from fungi to humans, means that, at any given time, in S phase, only a fraction of replication origins is activated. In recent years, a model has emerged to explain this pattern of DNA replication (1, 2). This model assumes that the pool of initiation factors required to fire licensed origins in S phase is limited, and therefore sufficient to fire only a subset of licensed origins at any given time. Licensed origins differ in their ability to recruit factors required for firing, so origins with higher affinity or accessibility fire earlier than those with lower affinity or accessibility. After activating the initial set of origins, firing factors are released, enabling the next set of origins to fire. This results in successive waves of origin activation. Genome replication eventually finishes when areas with the least accessible origins are replicated.In healthy human cells, the least accessible genomic regions consist of repetitive DNA, which represents about half of the genome and tends to be compacted into heterochromatin. However, recent studies suggest widespread opening of hetrochromatin during carcinogenesis and aging (3-5). Such reorganization of chromatin would expose a new suite of origins within repetitive DNA that could potentially compete initiation factors away from unique portions of the genome, thereby disrupting the normal genome-wide hierarchy of replication timing. Increased origin activity within repetitive DNA could thus compromise replication elsewhere in the genome. Given the limited pool of initiation factors, we propose that an increase in density of active origins within repetitive regions could result in a decreased density of such origins in unique regions of the genome, which, when combined with the stochastic nature of origin firing, may occasionally result in replication gaps, i.e., unique regions of the genome that are unable to complete replication before mitosis. This so-called "Random Replication Gap Problem" (RRGP) is the subject of long-standing speculation, but such gaps have never been experim...

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“…This effect is regulated by Rif1-dependent recruitment of protein phosphatase I, which may antagonize origin activation by the cyclin-and DBF4-dependent kinases (Lian et al 2011;Davé et al 2014;Hiraga et al 2014;Mattarocci et al 2014). Chromatin structure-in particular, histone deacetylation by Sir2 and Rpd3-also affects the timing of nontelomeric origins (Knott et al 2009(Knott et al , 2012Peace et al 2014;Yoshida et al 2014). However, the effect of chromatin structure on euchromatic origins is much weaker, and its mechanism is unclear.…”

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confidence: 99%

Replication timing is regulated by the number of MCMs loaded at origins

et al. 2015

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Replication timing is a crucial aspect of genome regulation that is strongly correlated with chromatin structure, gene expression, DNA repair, and genome evolution. Replication timing is determined by the timing of replication origin firing, which involves activation of MCM helicase complexes loaded at replication origins. Nonetheless, how the timing of such origin firing is regulated remains mysterious. Here, we show that the number of MCMs loaded at origins regulates replication timing. We show for the first time in vivo that multiple MCMs are loaded at origins. Because early origins have more MCMs loaded, they are, on average, more likely to fire early in S phase. Our results provide a mechanistic explanation for the observed heterogeneity in origin firing and help to explain how defined replication timing profiles emerge from stochastic origin firing. These results establish a framework in which further mechanistic studies on replication timing, such as the strong effect of heterochromatin, can be pursued.

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The Histone Deacetylases Sir2 and Rpd3 Act on Ribosomal DNA to Control the Replication Program in Budding Yeast

Cited by 104 publications

References 43 publications

The Chromatin and Transcriptional Landscape of NativeSaccharomyces cerevisiaeTelomeres and Subtelomeric Domains

The Chromatin and Transcriptional Landscape of NativeSaccharomyces cerevisiaeTelomeres and Subtelomeric Domains

SIR2 suppresses replication gaps and genome instability by balancing replication between repetitive and unique sequences

Replication timing is regulated by the number of MCMs loaded at origins

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