Genome stability is guarded by yeast Rtt105 through multiple mechanisms

Abstract Ty1 mobile DNA element is the most abundant and mutagenic retrotransposon present in the genome of the budding yeast Saccharomyces cerevisiae. Protein regulator of Ty1 transposition 105 (Rtt105) associates with large subunit of RPA and facilitates its loading onto a single-stranded DNA at replication forks. Here, we dissect the role of RTT105 in the maintenance of genome stability under normal conditions and upon various replication stresses through multiple genetic analyses. RTT105 is essential for viability in cells experiencing replication problems and in cells lacking functional S-phase checkpoints and DNA repair pathways involving homologous recombination. Our genetic analyses also indicate that RTT105 is crucial when cohesion is affected and is required for the establishment of normal heterochromatic structures. Moreover, RTT105 plays a role in telomere maintenance as its function is important for the telomere elongation phenotype resulting from the Est1 tethering to telomeres. Genetic analyses indicate that rtt105Δ affects the growth of several rfa1 mutants but does not aggravate their telomere length defects. Analysis of the phenotypes of rtt105Δ cells expressing NLS-Rfa1 fusion protein reveals that RTT105 safeguards genome stability through its role in RPA nuclear import but also by directly affecting RPA function in genome stability maintenance during replication.

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Ku80 is involved in telomere maintenance but dispensable for genomic stability in Leishmania mexicana

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0010041 ◽

2021 ◽

Vol 15 (12) ◽

pp. e0010041

Author(s):

Ester Poláková ◽

Amanda T. S. Albanaz ◽

Alexandra Zakharova ◽

Tatiana S. Novozhilova ◽

Evgeny S. Gerasimov ◽

...

Keyword(s):

Genome Stability ◽

Southern Blotting ◽

Telomere Maintenance ◽

Genome Integrity ◽

Whole Genome ◽

Leishmania Mexicana ◽

Telomere Elongation ◽

Ku Proteins ◽

Telomere Lengthening

Background Telomeres are indispensable for genome stability maintenance. They are maintained by the telomere-associated protein complex, which include Ku proteins and a telomerase among others. Here, we investigated a role of Ku80 in Leishmania mexicana. Leishmania is a genus of parasitic protists of the family Trypanosomatidae causing a vector-born disease called leishmaniasis. Methodology/Principal findings We used the previously established CRISPR/Cas9 system to mediate ablation of Ku80- and Ku70-encoding genes in L. mexicana. Complete knock-outs of both genes were confirmed by Southern blotting, whole-genome Illumina sequencing, and RT-qPCR. Resulting telomeric phenotypes were subsequently investigated using Southern blotting detection of terminal restriction fragments. The genome integrity in the Ku80- deficient cells was further investigated by whole-genome sequencing. Our work revealed that telomeres in the ΔKu80 L. mexicana are elongated compared to those of the wild type. This is a surprising finding considering that in another model trypanosomatid, Trypanosoma brucei, they are shortened upon ablation of the same gene. A telomere elongation phenotype has been documented in other species and associated with a presence of telomerase-independent alternative telomere lengthening pathway. Our results also showed that Ku80 appears to be not involved in genome stability maintenance in L. mexicana. Conclusion/Significance Ablation of the Ku proteins in L. mexicana triggers telomere elongation, but does not have an adverse impact on genome integrity.

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Endogenous oxidized DNA bases and APE1 regulate the formation of G-quadruplex structures in the genome

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1912355117 ◽

2020 ◽

Vol 117 (21) ◽

pp. 11409-11420 ◽

Cited By ~ 4

Author(s):

Shrabasti Roychoudhury ◽

Suravi Pramanik ◽

Hannah L. Harris ◽

Mason Tarpley ◽

Aniruddha Sarkar ◽

...

Keyword(s):

Excision Repair ◽

Factor Loading ◽

Telomere Maintenance ◽

Epigenetic Mechanism ◽

Dna Bases ◽

G Quadruplex ◽

Base Excision ◽

Ap Site ◽

In Cells

Formation of G-quadruplex (G4) DNA structures in key regulatory regions in the genome has emerged as a secondary structure-based epigenetic mechanism for regulating multiple biological processes including transcription, replication, and telomere maintenance. G4 formation (folding), stabilization, and unfolding must be regulated to coordinate G4-mediated biological functions; however, how cells regulate the spatiotemporal formation of G4 structures in the genome is largely unknown. Here, we demonstrate that endogenous oxidized guanine bases in G4 sequences and the subsequent activation of the base excision repair (BER) pathway drive the spatiotemporal formation of G4 structures in the genome. Genome-wide mapping of occurrence of Apurinic/apyrimidinic (AP) site damage, binding of BER proteins, and G4 structures revealed that oxidized base-derived AP site damage and binding of OGG1 and APE1 are predominant in G4 sequences. Loss of APE1 abrogated G4 structure formation in cells, which suggests an essential role of APE1 in regulating the formation of G4 structures in the genome. Binding of APE1 to G4 sequences promotes G4 folding, and acetylation of APE1, which enhances its residence time, stabilizes G4 structures in cells. APE1 subsequently facilitates transcription factor loading to the promoter, providing mechanistic insight into the role of APE1 in G4-mediated gene expression. Our study unravels a role of endogenous oxidized DNA bases and APE1 in controlling the formation of higher-order DNA secondary structures to regulate transcription beyond its well-established role in safeguarding the genomic integrity.

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Inflammation increases cells expressing ZSCAN4 and progenitor cell markers in the adult pancreas

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00299.2012 ◽

2013 ◽

Vol 304 (12) ◽

pp. G1103-G1116 ◽

Cited By ~ 7

Author(s):

Shigeru B. H. Ko ◽

Sakiko Azuma ◽

Yukihiro Yokoyama ◽

Akiko Yamamoto ◽

Kazuhiro Kyokane ◽

...

Keyword(s):

Autoimmune Pancreatitis ◽

Genome Stability ◽

Progenitor Cell ◽

Es Cells ◽

Embryonic Stem ◽

Corticosteroid Treatment ◽

Human Pancreas ◽

Cell Markers ◽

Telomere Elongation

We have recently identified the zinc finger and SCAN domain containing 4 (Zscan4), which is transiently expressed and regulates telomere elongation and genome stability in mouse embryonic stem (ES) cells. The aim of this study was to examine the expression of ZSCAN4 in the adult pancreas and elucidate the role of ZSCAN4 in tissue inflammation and subsequent regeneration. The expression of ZSCAN4 and other progenitor or differentiated cell markers in the human pancreas was immunohistochemically examined. Pancreas sections of alcoholic or autoimmune pancreatitis patients before and under maintenance corticosteroid treatment were used in this study. In the adult human pancreas a small number of ZSCAN4-positive (ZSCAN4+) cells are present among cells located in the islets of Langerhans, acini, ducts, and oval-shaped cells. These cells not only express differentiated cell markers for each compartment of the pancreas but also express other tissue stem/progenitor cell markers. Furthermore, the number of ZSCAN4+cells dramatically increased in patients with chronic pancreatitis, especially in the pancreatic tissues of autoimmune pancreatitis actively regenerating under corticosteroid treatment. Interestingly, a number of ZSCAN4+cells in the pancreas of autoimmune pancreatitis returned to the basal level after 1 yr of maintenance corticosteroid treatment. In conclusion, coexpression of progenitor cell markers and differentiated cell markers with ZSCAN4 in each compartment of the pancreas may indicate the presence of facultative progenitors for both exocrine and endocrine cells in the adult pancreas.

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Role for the Related Poly(ADP-Ribose) Polymerases Tankyrase 1 and 2 at Human Telomeres

Molecular and Cellular Biology ◽

10.1128/mcb.22.1.332-342.2002 ◽

2002 ◽

Vol 22 (1) ◽

pp. 332-342 ◽

Cited By ~ 197

Author(s):

Brandoch D. Cook ◽

Jasmin N. Dynek ◽

William Chang ◽

Grigoriy Shostak ◽

Susan Smith

Keyword(s):

Potential Role ◽

Telomere Maintenance ◽

Telomeric Dna ◽

Continuous Growth ◽

Telomere Elongation ◽

Bona Fide ◽

Tankyrase 1 ◽

Growth Of Tumor

ABSTRACT Telomere maintenance is essential for the continuous growth of tumor cells. In most human tumors telomeres are maintained by telomerase, a specialized reverse transcriptase. Tankyrase 1, a human telomeric poly(ADP-ribose) polymerase (PARP), positively regulates telomere length through its interaction with TRF1, a telomeric DNA-binding protein. Tankyrase 1 ADP-ribosylates TRF1, inhibiting its binding to telomeric DNA. Overexpression of tankyrase 1 in the nucleus promotes telomere elongation, suggesting that tankyrase 1 regulates access of telomerase to the telomeric complex. The recent identification of a closely related homolog of tankyrase 1, tankyrase 2, opens the possibility for a second PARP at telomeres. We therefore sought to establish the role of tankyrase 1 at telomeres and to determine if tankyrase 2 might have a telomeric function. We show that endogenous tankyrase 1 is a component of the human telomeric complex. We demonstrate that telomere elongation by tankyrase 1 requires the catalytic activity of the PARP domain and does not occur in telomerase-negative primary human cells. To investigate a potential role for tankyrase 2 at telomeres, recombinant tankyrase 2 was subjected to an in vitro PARP assay. Tankyrase 2 poly(ADP-ribosyl)ated itself and TRF1. Overexpression of tankyrase 2 in the nucleus released endogenous TRF1 from telomeres. These findings establish tankyrase 2 as a bona fide PARP, with itself and TRF1 as acceptors of ADP-ribosylation, and suggest the possibility of a role for tankyrase 2 at telomeres.

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Transcriptional activity of TRF2 is telomere length dependent

10.1101/056481 ◽

2016 ◽

Author(s):

Ananda Kishore Mukherjee ◽

Shalu Sharma ◽

Parashar Dhapola ◽

Dhurjhoti Saha ◽

Tabish Hussain ◽

...

Keyword(s):

Telomere Length ◽

Genome Stability ◽

Telomere Maintenance ◽

Regulatory Control ◽

Gene Promoters ◽

Multiple Gene ◽

Telomere Repeat ◽

Genome Wide ◽

Binding Factor

AbstractTRF2 is a telomere repeat binding factor crucial for telomere maintenance and genome stability. An emerging non-conventional role of TRF2 is as a transcriptional regulator through extra-telomeric bindings. Herein we report that increase in telomere length leads to sequestration of TRF2 at the telomeres leading to reduced extra-telomeric TRF2 occupancy genome wide. Decrease in TRF2 occupancy was found on multiple gene promoters in cells with elongated telomeres, including the cell cycle regulator kinase-p21. We found that TRF2 is a transcriptional repressor of p21, and, interestingly, TRF2-mediated regulatory control of p21 is telomere length dependent.

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Telomeres and Cancer

Life ◽

10.3390/life11121405 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1405

Author(s):

Hueng-Chuen Fan ◽

Fung-Wei Chang ◽

Jeng-Dau Tsai ◽

Kao-Min Lin ◽

Chuan-Mu Chen ◽

...

Keyword(s):

Telomere Length ◽

Molecular Mechanisms ◽

Telomere Maintenance ◽

Cancer Development ◽

Telomere Elongation ◽

Metabolism Pathway ◽

Length Regulation ◽

Telomere Length Regulation ◽

Genome Protection

Telomeres cap the ends of eukaryotic chromosomes and are indispensable chromatin structures for genome protection and replication. Telomere length maintenance has been attributed to several functional modulators, including telomerase, the shelterin complex, and the CST complex, synergizing with DNA replication, repair, and the RNA metabolism pathway components. As dysfunctional telomere maintenance and telomerase activation are associated with several human diseases, including cancer, the molecular mechanisms behind telomere length regulation and protection need particular emphasis. Cancer cells exhibit telomerase activation, enabling replicative immortality. Telomerase reverse transcriptase (TERT) activation is involved in cancer development through diverse activities other than mediating telomere elongation. This review describes the telomere functions, the role of functional modulators, the implications in cancer development, and the future therapeutic opportunities.

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HeterozygousRTEL1mutations are associated with familial pulmonary fibrosis

European Respiratory Journal ◽

10.1183/09031936.00040115 ◽

2015 ◽

Vol 46 (2) ◽

pp. 474-485 ◽

Cited By ~ 85

Author(s):

Caroline Kannengiesser ◽

Raphael Borie ◽

Christelle Ménard ◽

Marion Réocreux ◽

Patrick Nitschké ◽

...

Keyword(s):

Pulmonary Fibrosis ◽

Genome Stability ◽

Dna Helicase ◽

Telomere Maintenance ◽

Candidate Gene Approach ◽

Autosomal Dominant Trait ◽

Telomere Shortening ◽

Telomere Elongation ◽

Whole Exome ◽

Familial Pulmonary Fibrosis

Pulmonary fibrosis is a fatal disease with progressive loss of respiratory function. Defective telomere maintenance leading to telomere shortening is a cause of pulmonary fibrosis, as mutations in the telomerase component genesTERT(reverse transcriptase) andTERC(RNA component) are found in 15% of familial pulmonary fibrosis (FPF) cases. However, so far, about 85% of FPF remain genetically uncharacterised.Here, in order to identify new genetic causes of FPF, we performed whole-exome sequencing, with a candidate-gene approach, of 47 affected subjects from 35 families with FPF withoutTERTandTERCmutations.We identified heterozygous mutations in regulator of telomere elongation helicase 1 (RTEL1) in four families. RTEL1 is a DNA helicase with roles in DNA replication, genome stability, DNA repair and telomere maintenance. The heterozygousRTEL1mutations segregated as an autosomal dominant trait in FPF, and were predicted by structural analyses to severely affect the function and/or stability of RTEL1. In agreement with this,RTEL1-mutated patients exhibited short telomeres in comparison with age-matched controls.Our results provide evidence that heterozygousRTEL1mutations are responsible for FPF and, thereby, extend the clinical spectrum of RTEL1 deficiency. Thus,RTEL1enlarges the number of telomere-associated genes implicated in FPF.

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Multifunctional Role of ATM/Tel1 Kinase in Genome Stability: From the DNA Damage Response to Telomere Maintenance

BioMed Research International ◽

10.1155/2014/787404 ◽

2014 ◽

Vol 2014 ◽

pp. 1-17 ◽

Cited By ~ 16

Author(s):

Enea Gino Di Domenico ◽

Elena Romano ◽

Paola Del Porto ◽

Fiorentina Ascenzioni

Keyword(s):

Dna Damage ◽

Dna Damage Response ◽

Ataxia Telangiectasia ◽

Genome Stability ◽

Genetic Disorder ◽

Cell Cycle Control ◽

Premature Aging ◽

Telomere Maintenance ◽

Damage Response

The mammalian protein kinase ataxia telangiectasia mutated (ATM) is a key regulator of the DNA double-strand-break response and belongs to the evolutionary conserved phosphatidylinositol-3-kinase-related protein kinases. ATM deficiency causes ataxia telangiectasia (AT), a genetic disorder that is characterized by premature aging, cerebellar neuropathy, immunodeficiency, and predisposition to cancer. AT cells show defects in the DNA damage-response pathway, cell-cycle control, and telomere maintenance and length regulation. Likewise, inSaccharomyces cerevisiae, haploid strains defective in theTEL1gene, the ATM ortholog, show chromosomal aberrations and short telomeres. In this review, we outline the complex role of ATM/Tel1 in maintaining genomic stability through its control of numerous aspects of cellular survival. In particular, we describe how ATM/Tel1 participates in the signal transduction pathways elicited by DNA damage and in telomere homeostasis and its importance as a barrier to cancer development.

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Telomere Targeting Approaches in Cancer: Over the Length Maintenance.

10.20944/preprints202111.0367.v1 ◽

2021 ◽

Author(s):

Eleonora Vertecchi ◽

Angela Rizzo ◽

Erica Salvati

Keyword(s):

Genome Stability ◽

Telomere Maintenance ◽

Cancer Drug ◽

Signalling Pathways ◽

Telomere Elongation ◽

Intracellular Signalling Pathways ◽

Anti Cancer ◽

Cancer Cell Survival ◽

Dna Damage Signalling ◽

Telomere Length Homeostasis

Telomeres are crucial structures that preserve genome stability. Their progressive erosion over rounds of DNA duplication determines senescence of cells and organisms. Telomere length homeostasis is critical for cancer development then telomere maintenance mechanisms are established targets in cancer treatment. Besides telomere elongation, telomere’s dysfunction impinges on intracellular signalling pathways, in particular DNA damage signalling and repair affecting cancer cell survival and proliferation. This review summarizes and discusses about the recent findings in anti-cancer drug development targeting different “telosome” components.

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Chromosome End Maintenance by Telomerase

Journal of Biological Chemistry ◽

10.1074/jbc.r900011200 ◽

2009 ◽

Vol 284 (24) ◽

pp. 16061-16065 ◽

Cited By ~ 66

Author(s):

Jennifer L. Osterhage ◽

Katherine L. Friedman

Keyword(s):

Genome Stability ◽

Chromosomal Abnormalities ◽

Human Aging ◽

Dna Complexes ◽

Telomeric Sequences ◽

Telomere Elongation ◽

Telomere Function ◽

Multiple Levels ◽

Linear Chromosomes

Telomeres, protein-DNA complexes at the ends of eukaryotic linear chromosomes, are essential for genome stability. The accumulation of chromosomal abnormalities in the absence of proper telomere function is implicated in human aging and cancer. Repetitive telomeric sequences are maintained by telomerase, a ribonucleoprotein complex containing a reverse transcriptase subunit, a template RNA, and accessory components. Telomere elongation is regulated at multiple levels, including assembly of the telomerase holoenzyme, recruitment of telomerase to the chromosome terminus, and telomere accessibility. This minireview provides an overview of telomerase structure, function, and regulation and the role of telomerase in human disease.

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