De novo assembly of a PML nuclear subcompartment occurs through multiple pathways and induces telomere elongation

Chung, Inn; Leonhardt, Heinrich; Rippe, Karsten

doi:10.1242/jcs.084681

Cited by 81 publications

(90 citation statements)

References 70 publications

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“…Notably, long-term PML knockdown induced telomere shortening and significantly increased the number of chromosomal ends where a telomere repeat signal was absent. This demonstrates that PML is crucial for telomere elongation in ALT cells and confirms previous conclusions (Chung et al, 2011;Jiang et al, 2005). Although inhibition of the ALT mechanism by other means has been employed previously (Jiang et al, 2005;Potts and Yu, 2007), our study is the first to reveal the crucial contribution of PML by showing a telomere shortening upon its knockdown.…”

Section: Discussionsupporting

confidence: 90%

“…Accordingly, the effect of protein knockdown might be different from what is observed under the conditions used here for U2OS cells. A role for DNA repair proteins downstream of APB formation is also supported by our previous findings (Chung et al, 2011). Some repair proteins were inefficient in inducing the de novo formation of APBs, but instead were recruited to pre-assembled APBs.…”

Section: Discussionsupporting

confidence: 81%

“…We next employed a previously introduced technique to induce the de novo formation of ectopic APBs by recruiting GFP-tagged proteins to three telomeres in U2OS cells with stably integrated lac operator (lacO) arrays (Chung et al, 2011;Jegou et al, 2009). As controls, GFP alone was recruited ( Fig.…”

Section: An Rnai Screen With Automated 3d Image Analysis Identifies 2mentioning

confidence: 99%

“…ALT tumors are typically characterized by a large heterogeneity in telomere length within one cell (Bryan et al, 1995), the occurrence of extrachromosomal telomeric repeats (ECTRs) (Wang et al, 2004), mutations of the chromatin remodeler ATRX (Heaphy et al, 2011), genome instability (Lovejoy et al, 2012), increased telomeric recombination (Londoño-Vallejo et al, 2004) and the presence of ALT-associated promyelocytic leukemia (PML) nuclear bodies (APBs) (Chung et al, 2012;Yeager et al, 1999). APBs are defined as complexes of PML nuclear bodies (PML-NBs) with telomeric DNA in telomerase-negative cells (Yeager et al, 1999), and their ectopic assembly in ALT-positive cells induces telomere lengthening by promoting repair-associated DNA synthesis (Chung et al, 2011). A number of proteins involved in ALT have been identified, such as the telomeric shelterin complex (Jiang et al, 2007), the small ubiquitin-like modifier (SUMO) E3 ligase MMS21 (also known as NSMCE2) (Potts and Yu, 2007), several DNA repair proteins (Nabetani and Ishikawa, 2011), as well as heterochromatin protein 1 (HP1) family proteins (Jiang et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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PML induces compaction, TRF2 depletion and DNA damage signaling at telomeres and promotes their alternative lengthening

Osterwald

Deeg

Chung

et al. 2015

Journal of Cell Science

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The alternative lengthening of telomeres (ALT) mechanism allows cancer cells to escape senescence and apoptosis in the absence of active telomerase. A characteristic feature of this pathway is the assembly of ALT-associated promyelocytic leukemia (PML) nuclear bodies (APBs) at telomeres. Here, we dissected the role of APBs in a human ALT cell line by performing an RNA interference screen using an automated 3D fluorescence microscopy platform and advanced 3D image analysis. We identified 29 proteins that affected APB formation, which included proteins involved in telomere and chromatin organization, protein sumoylation and DNA repair. By integrating and extending these findings, we found that APB formation induced clustering of telomere repeats, telomere compaction and concomitant depletion of the shelterin protein TRF2 (also known as TERF2). These APB-dependent changes correlated with the induction of a DNA damage response at telomeres in APBs as evident by a strong enrichment of the phosphorylated form of the ataxia telangiectasia mutated (ATM) kinase. Accordingly, we propose that APBs promote telomere maintenance by inducing a DNA damage response in ALT-positive tumor cells through changing the telomeric chromatin state to trigger ATM phosphorylation.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 81%

Section: An Rnai Screen With Automated 3d Image Analysis Identifies 2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

PML induces compaction, TRF2 depletion and DNA damage signaling at telomeres and promotes their alternative lengthening

Osterwald

Deeg

Chung

et al. 2015

Journal of Cell Science

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“…4) inhibited accumulation of viral protein ICP27. SUMOylation has been linked to many cellular processes, including formation of ND10 bodies (86). vi) It is noteworthy that depletion of Ddx17 resulted in a decrease in Influenza virus yield and a decrease in the accumulation of viral RNAs (64).…”

Section: Discussionmentioning

confidence: 99%

Use of biotinylated plasmid DNA as a surrogate for HSV DNA to identify proteins that repress or activate viral gene expression

Mallon¹,

Wakim²,

Roizman³

2012

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

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ICP0, a key herpes simplex virus regulatory protein, functions first in the nucleus and then in the cytoplasm. The duration of its nuclear sojourn in cells transfected with DNA and then infected is related to the quantity of transfected DNA. Furthermore, ICP0 transactivates both viral genes and genes encoded by the transfected DNA. The data support the hypothesis that ICP0 is retained in the nucleus until it completes the replacement of repressive chromatin with effector proteins that enable transcription of both DNA templates. To identify the effector proteins, we transfected cells with biotinylated DNA encoding a nonviral gene and then infected the cells with wild-type virus. Proteins bound to transfected biotinylated plasmid recovered from mock-treated and infected cells were identified using mass spectrometry followed by appropriate database search. The transfected DNA from mock-infected cells yielded proteins associated with repression, whereas DNA recovered from infected cells included proteins known to enable transcription and proteins that have not been previously associated with that role. To test the hypothesis that the proteins hitherto not known to associate with viral gene expression are nevertheless essential, we tested the role of the DEAD-box helicase Ddx17. We report that Ddx17 plays a critical role in the expression of early and late viral genes. Thus, biotinylated DNA recovered from transfected infected cells can function as a surrogate for viral DNA and is a rich source of proteins that play a role in viral gene expression but which have not been previously identified in that role. DNA binding proteins | gene derepressionU pon entry into the nucleus, the DNA of HSV-1 is immediately coated by repressive cellular proteins and bound to a dynamic nuclear body known as ND10 (1). Expression of viral genes requires sequential derepression at least at two checkpoints (2). In the first VP16, a viral tegument protein introduced into the cell during infection, recruits to the promoters of the α (immediate early) genes numerous host proteins that include the Octamer binding protein 1, Host cell factor 1, and Lysine Specific Demethylase 1 (LSD1) (1, 2). The consequence of derepression of the α genes is the synthesis of the six α proteins. One of these proteins, ICP0, plays a key role in the transition through the second checkpoint. Briefly, newly synthesized ICP0 colocalizes with ND10, recruits the ubiquitin-conjugating enzyme UbcH5a, and mediates the degradation of PML and SP100, key components of the ND10 nuclear bodies (3-5). In addition, it interacts with a repressor complex whose key components are HDAC-1/2, CoREST, LSD1, and REST. In this instance ICP0 binds to CoREST and dislodges HDAC-1/2 from the repressor complex (6-8). Last, ICP0 either recruits or enhances the recruitment of numerous host proteins to the viral replication compartment erected in the space formerly occupied by the ND10 nuclear bodies. These include cyclin D3, cdc34, CoREST, USP7, Bmal1, and the histone acetyl transferase CLOCK (...

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Protein Condensates Unfold G‐Quadruplex Resembling a Helicase Activity

Luo,

Ji,

et al. 2024

ChemBioChem

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Membrane‐less organelles, formed by liquid‐liquid phase separation, participate in many vital cellular processes and have received extensive attention recently. A notable form of noncanonical nucleic acid secondary structure, G‐quadruplex (G4), interacts with the scaffolding proteins in these membrane‐less organelles and becomes an integral part of this condensed phase. However, the structure and stability features of the integrated G4 remain poorly characterized. Herein, we employed NMR along with other biophysical methods to investigate the conformation of a G4 within condensates formed by a disordered protein known as DDX4N1. We discovered that the human telomeric sequence MHT24, which forms a G4 structure in a non‐condensed phase solution of protein DDX4N1, unfolds when it is within DDX4N1 condensates due to phase separation. Our findings provide an instance of a protein acquiring new functionality through phase separation process, which deepen our understanding of how protein condensates regulate G4 structure and their functions.

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De novo assembly of a PML nuclear subcompartment occurs through multiple pathways and induces telomere elongation

Cited by 81 publications

References 70 publications

PML induces compaction, TRF2 depletion and DNA damage signaling at telomeres and promotes their alternative lengthening

PML induces compaction, TRF2 depletion and DNA damage signaling at telomeres and promotes their alternative lengthening

Use of biotinylated plasmid DNA as a surrogate for HSV DNA to identify proteins that repress or activate viral gene expression

Protein Condensates Unfold G‐Quadruplex Resembling a Helicase Activity

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