Human Rap1 Interacts Directly with Telomeric DNA and Regulates TRF2 Localization at the Telomere

Arat, N. Özlem; Griffith, Jack D.

doi:10.1074/jbc.m112.415984

Cited by 54 publications

(74 citation statements)

References 48 publications

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“…The observed selectivity increase is in a very good accordance with the results obtained recently from gel retardation assays by Arat and Griffith (18). Additionally, when we studied Rap1 effect on DNA binding of TRF2, we found that Rap1 induced TRF2 release from telomeric DNA duplexes.…”

Section: Discussionsupporting

confidence: 92%

Human Rap1 modulates TRF2 attraction to telomeric DNA

Janoušková

Nečasová

Pavloušková

et al. 2015

Nucleic Acids Research

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More than two decades of genetic research have identified and assigned main biological functions of shelterin proteins that safeguard telomeres. However, a molecular mechanism of how each protein subunit contributes to the protecting function of the whole shelterin complex remains elusive. Human Repressor activator protein 1 (Rap1) forms a multifunctional complex with Telomeric Repeat binding Factor 2 (TRF2). Rap1–TRF2 complex is a critical part of shelterin as it suppresses homology-directed repair in Ku 70/80 heterodimer absence. To understand how Rap1 affects key functions of TRF2, we investigated full-length Rap1 binding to TRF2 and Rap1–TRF2 complex interactions with double-stranded DNA by quantitative biochemical approaches. We observed that Rap1 reduces the overall DNA duplex binding affinity of TRF2 but increases the selectivity of TRF2 to telomeric DNA. Additionally, we observed that Rap1 induces a partial release of TRF2 from DNA duplex. The improved TRF2 selectivity to telomeric DNA is caused by less pronounced electrostatic attractions between TRF2 and DNA in Rap1 presence. Thus, Rap1 prompts more accurate and selective TRF2 recognition of telomeric DNA and TRF2 localization on single/double-strand DNA junctions. These quantitative functional studies contribute to the understanding of the selective recognition of telomeric DNA by the whole shelterin complex.

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Section: Discussionsupporting

confidence: 92%

Human Rap1 modulates TRF2 attraction to telomeric DNA

Janoušková

Nečasová

Pavloušková

et al. 2015

Nucleic Acids Research

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“…For example, overexpression of Trf2, which recruits hRap1 to DNA, can reduce nucleosome density within telomere chromatin, which suggests that the hRap1:Trf2 complex may modify chromatin (Galati et al 2012). Also, the recent demonstrations that mammalian Rap1 not only localizes to telomeres but also can bind with some affinity to DNA itself, contribute to the transcriptional regulation of sites throughout the genome, and bind several histone proteins raise the possibility that mammalian Rap1 may contribute to changes in chromatin and gene expression in senescent cells (Martinez et al 2010;Lee et al 2011;Yang et al 2011;Arat and Griffith 2012).…”

Section: Discussionmentioning

confidence: 99%

Rap1 relocalization contributes to the chromatin-mediated gene expression profile and pace of cell senescence

et al. 2013

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Cellular senescence is accompanied by dramatic changes in chromatin structure and gene expression. Using Saccharomyces cerevisiae mutants lacking telomerase (tlc1D) to model senescence, we found that with critical telomere shortening, the telomere-binding protein Rap1 (repressor activator protein 1) relocalizes to the upstream promoter regions of hundreds of new target genes. The set of new Rap1 targets at senescence (NRTS) is preferentially activated at senescence, and experimental manipulations of Rap1 levels indicate that it contributes directly to NRTS activation. A notable subset of NRTS includes the core histone-encoding genes; we found that Rap1 contributes to their repression and that histone protein levels decline at senescence. Rap1 and histones also display a target site-specific antagonism that leads to diminished nucleosome occupancy at the promoters of upregulated NRTS. This antagonism apparently impacts the rate of senescence because underexpression of Rap1 or overexpression of the core histones delays senescence. Rap1 relocalization is not a simple consequence of lost telomere-binding sites, but rather depends on the Mec1 checkpoint kinase. Rap1 relocalization is thus a novel mechanism connecting DNA damage responses (DDRs) at telomeres to global changes in chromatin and gene expression while driving the pace of senescence.

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“…Electron microscopy analysis of t-loop formation has revealed that the Rap1–TRF2 complex, compared to TRF2 alone, is much more prone to bind telomeric DNA and to form t loops 18 . Rap1 binding to TRF2 also decreases electrostatic interactions between double-stranded DNA and the TRF2 basic domain, thereby decreasing nonspecific binding of TRF2 to DNA and increasing the specificity of TRF2 for telomeric DNA 19 .…”

Section: The End Protection Problem: Inhibition Of the Ddrmentioning

confidence: 99%

“…Steps of DNA damage–repair inhibition by shelterin or accessory factors are highlighted by red circles. (1) TRF2, potentially through its TRFH domain, and supported by Rap1, forms the t loop, a DNA structure that hides chromosome ends from the MRN–ATM factors 7–9,18 . (2) The t loop also prevents loading of the Ku heterodimer on chromosome ends.…”

Section: Figurementioning

confidence: 99%

Complex interactions between the DNA-damage response and mammalian telomeres

Arnoult

Karlseder

2015

Nat Struct Mol Biol

175

168

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Natural chromosome ends resemble double-stranded DNA breaks, but they do not activate a damage response in healthy cells. Telomeres therefore have evolved to solve the ‘end-protection problem’ by inhibiting multiple DNA damage–response pathways. During the past decade, the view of telomeres has progressed from simple caps that hide chromosome ends to complex machineries that have an active role in organizing the genome. Here we focus on mammalian telomeres and summarize and interpret recent discoveries in detail, focusing on how repair pathways are inhibited, how resection and replication are controlled and how these mechanisms govern cell fate during senescence, crisis and transformation.

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Human Rap1 Interacts Directly with Telomeric DNA and Regulates TRF2 Localization at the Telomere

Cited by 54 publications

References 48 publications

Human Rap1 modulates TRF2 attraction to telomeric DNA

Human Rap1 modulates TRF2 attraction to telomeric DNA

Rap1 relocalization contributes to the chromatin-mediated gene expression profile and pace of cell senescence

Complex interactions between the DNA-damage response and mammalian telomeres

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