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Székvölgyi L. Chromosomal R-loops: who R they? Biol Futur 2024; 75:177-182. [PMID: 38457033 DOI: 10.1007/s42977-024-00213-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 02/14/2024] [Indexed: 03/09/2024]
Abstract
R-loops, composed of DNA-RNA hybrids and displaced single-stranded DNA, are known to pose a severe threat to genome integrity. Therefore, extensive research has focused on identifying regulatory proteins involved in controlling R-loop levels. These proteins play critical roles in preventing R-loop accumulation and associated genome instability. Herein I summarize recent knowledge on R-loop regulators affecting R-loop homeostasis, involving a wide array of R-loop screening methods that have enabled their characterization, from forward genetic and siRNA-based screens to proximity labeling and machine learning. These approaches not only deepen our understanding on R-loop formation processes, but also hold promise to find new targets in R-loop dysregulation associated with human pathologies.
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Affiliation(s)
- Lóránt Székvölgyi
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Department of Molecular and Nanopharmaceutics, Faculty of Pharmacy, University of Debrecen, Debrecen, 4032, Hungary.
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2
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Piljukov VJ, Sillamaa S, Sedman T, Garber N, Rätsep M, Freiberg A, Sedman J. Mitochondrial Irc3 helicase of the thermotolerant yeast Ogataea polymorpha displays dual DNA- and RNA-stimulated ATPase activity. Mitochondrion 2023; 69:130-139. [PMID: 36764503 DOI: 10.1016/j.mito.2023.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 02/02/2023] [Accepted: 02/04/2023] [Indexed: 02/11/2023]
Abstract
Irc3 is one of the six mitochondrial helicases described in Saccharomyces cerevisiae. Physiological functions of Irc3 are not completely understood as both DNA metabolic processes and mRNA translation have been suggested to be direct targets of the helicase. In vitro analysis of Irc3 has been hampered by the modest thermostability of the S. cerevisiae protein. Here, we purified a homologous helicase (Irc3op) of the thermotolerant yeast Ogataea polymorpha that retains structural integrity and catalytic activity at temperatures above 40 °C. Irc3op can complement the respiratory deficiency phenotype of a S. cerevisiae irc3Δ mutant, indicating conservation of biochemical functions. The ATPase activity of Irc3op is best stimulated by branched and double- stranded DNA cofactors. Single-stranded DNA binds Irc3op tightly but is a weak activator of the ATPase activity. We could also detect a lower level stimulation with RNA, especially with molecules possessing a compact three-dimensional structure. These results support the idea that that Irc3 might have dual specificity and remodel both DNA and RNA molecules in vivo. Furthermore, our analysis of kinetic parameters predicts that Irc3 could have a regulatory function via sensing changes of the mitochondrial ATP pool or respond to the accumulation of single-stranded DNA.
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Affiliation(s)
- Vlad-Julian Piljukov
- Department of Biochemistry, Institute of Molecular and Cell Biology, University of Tartu, Riia 23B, 51010 Tartu, Estonia
| | - Sirelin Sillamaa
- Department of Biochemistry, Institute of Molecular and Cell Biology, University of Tartu, Riia 23B, 51010 Tartu, Estonia
| | - Tiina Sedman
- Department of Biochemistry, Institute of Molecular and Cell Biology, University of Tartu, Riia 23B, 51010 Tartu, Estonia
| | - Natalja Garber
- Department of Biochemistry, Institute of Molecular and Cell Biology, University of Tartu, Riia 23B, 51010 Tartu, Estonia
| | - Margus Rätsep
- Laboratory of Biophysics, Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu, Estonia
| | - Arvi Freiberg
- Laboratory of Biophysics, Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu, Estonia
| | - Juhan Sedman
- Department of Biochemistry, Institute of Molecular and Cell Biology, University of Tartu, Riia 23B, 51010 Tartu, Estonia.
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3
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Belotserkovskii BP, Hanawalt PC. Topology and kinetics of R-loop formation. Biophys J 2022; 121:3345-3357. [PMID: 36004778 PMCID: PMC9515371 DOI: 10.1016/j.bpj.2022.08.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/06/2022] [Accepted: 08/18/2022] [Indexed: 11/19/2022] Open
Abstract
R-loops are structures containing an RNA-DNA duplex and an unpaired DNA strand. They can be formed upon "invasion" of an RNA strand into a DNA duplex, during which the RNA displaces the homologous DNA strand and binds the complementary strand. R-loops have many significant beneficial or deleterious biological effects, so it is important to understand the mechanisms for their generation and processing. We propose a model for co-transcriptional R-loop formation, in which their generation requires passage of the nascent RNA "tail" through the gap between the separated DNA strands. This passage becomes increasingly difficult with lengthening of the RNA tail. The length of the tail increases upon increasing distance between the transcription start site and the site of R-loop initiation. This causes reduced yields of R-loops with greater distance from the transcription start site. However, alternative pathways for R-loop formation are possible, involving either transient disruption of the transcription complex or the hypothetical formation of a triple-stranded structure, as a "collapsed R-loop." These alternative pathways could account for the fact that in many systems R-loops are observed very far from the transcription start site. Our model is consistent with experimental data and makes general predictions about the kinetics of R-loop formation.
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4
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Transcription Inhibition by PNA-Induced R-Loops. Methods Mol Biol 2021; 2105:141-155. [PMID: 32088868 DOI: 10.1007/978-1-0716-0243-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
R-loops are structures consisting of an RNA-DNA duplex and an unpaired DNA strand. They can form during transcription upon nascent RNA "threadback" invasion into the DNA duplex to displace the non-template DNA strand. R-loops occur naturally in all kingdoms of life, and they have multiple biological effects. Therefore, it is of interest to study the artificial induction of R-loops and to monitor their effects in model in vitro systems to learn mechanisms. Here we describe transcription blockage in vitro by R-loop formation induced by peptide nucleic acid (PNA) binding to the non-template DNA strand.
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Hegazy YA, Fernando CM, Tran EJ. The balancing act of R-loop biology: The good, the bad, and the ugly. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49903-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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6
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Hegazy YA, Fernando CM, Tran EJ. The balancing act of R-loop biology: The good, the bad, and the ugly. J Biol Chem 2019; 295:905-913. [PMID: 31843970 DOI: 10.1074/jbc.rev119.011353] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
An R-loop is a three-stranded nucleic acid structure that consists of a DNA:RNA hybrid and a displaced strand of DNA. R-loops occur frequently in genomes and have significant physiological importance. They play vital roles in regulating gene expression, DNA replication, and DNA and histone modifications. Several studies have uncovered that R-loops contribute to fundamental biological processes in various organisms. Paradoxically, although they do play essential positive functions required for important biological processes, they can also contribute to DNA damage and genome instability. Recent evidence suggests that R-loops are involved in a number of human diseases, including neurological disorders, cancer, and autoimmune diseases. This review focuses on the molecular basis for R-loop-mediated gene regulation and genomic instability and briefly discusses methods for identifying R-loops in vivo It also highlights recent studies indicating the role of R-loops in DNA double-strand break repair with an updated view of much-needed future goals in R-loop biology.
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Affiliation(s)
- Youssef A Hegazy
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | | | - Elizabeth J Tran
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907 .,Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
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7
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Holt IJ. The mitochondrial R-loop. Nucleic Acids Res 2019; 47:5480-5489. [PMID: 31045202 PMCID: PMC6582354 DOI: 10.1093/nar/gkz277] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/11/2019] [Accepted: 04/29/2019] [Indexed: 12/18/2022] Open
Abstract
The DNA in mitochondria contributes essential components of the organelle’s energy producing machinery that is essential for life. In 1971, many mitochondrial DNA molecules were found to have a third strand of DNA that maps to a region containing critical regulatory elements for transcription and replication. Forty-five years later, a third strand of RNA in the same region has been reported. This mitochondrial R-loop is present on thousands of copies of mitochondrial DNA per cell making it potentially the most abundant R-loop in nature. Here, I assess the discovery of the mitochondrial R-loop, discuss why it remained unrecognized for almost half a century and propose for it central roles in the replication, organization and expression of mitochondrial DNA, which if compromised can lead to disease states.
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Affiliation(s)
- Ian J Holt
- Biodonostia Health Research Institute, 20014 San Sebastián, Spain & IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.,Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London, NW3 2PF, UK.,CIBERNED (Center for Networked Biomedical Research on Neurodegenerative Diseases, Ministry of Economy and Competitiveness, Institute Carlos III), Madrid, Spain
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9
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Song Y, Xuan A, Bu C, Ci D, Tian M, Zhang D. Osmotic stress-responsive promoter upstream transcripts (PROMPTs) act as carriers of MYB transcription factors to induce the expression of target genes in Populus simonii. PLANT BIOTECHNOLOGY JOURNAL 2019; 17:164-177. [PMID: 29797449 PMCID: PMC6330638 DOI: 10.1111/pbi.12955] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 05/12/2018] [Accepted: 05/21/2018] [Indexed: 05/22/2023]
Abstract
Complex RNA transcription and processing produces a diverse range catalog of long noncoding RNAs (lncRNAs), important biological regulators that have been implicated in osmotic stress responses in plants. Promoter upstream transcript (PROMPT) lncRNAs share some regulatory elements with the promoters of their neighbouring protein-coding genes. However, their function remains unknown. Here, using strand-specific RNA sequencing, we identified 209 differentially regulated osmotic-responsive PROMPTs in poplar (Populus simonii). PROMPTs are transcribed bidirectionally and are more stable than other lncRNAs. Co-expression analysis of PROMPTs and protein-coding genes divided the regulatory network into five independent subnetworks including 27 network modules. Significantly enriched PROMPTs in the network were selected to validate their regulatory roles. We used delaminated layered double hydroxide lactate nanosheets (LDH-lactate-NS) to transport synthetic nucleic acids into live tissues to mimic overexpression and interference of a specific PROMPT. The altered expression of PROMPT_1281 induced the expression of its cis and trans targets, and this interaction was governed by its secondary structure rather than just its primary sequence. Based on this example, we proposed a model that a concentration gradient of PROMPT_1281 is established, which increases the probability of its interaction with targets near its transcription site that shares common motifs. Our results firstly demonstrated that PROMPT_1281 act as carriers of MYB transcription factors to induce the expression of target genes under osmotic stress. In sum, our study identified and validated a set of poplar PROMPTs that likely have regulatory functions in osmotic responses.
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Affiliation(s)
- Yuepeng Song
- Beijing Advanced Innovation Center for Tree Breeding by Molecular DesignBeijing Forestry UniversityBeijingChina
- National Engineering Laboratory for Tree BreedingCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental PlantsCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
| | - Anran Xuan
- Beijing Advanced Innovation Center for Tree Breeding by Molecular DesignBeijing Forestry UniversityBeijingChina
- National Engineering Laboratory for Tree BreedingCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental PlantsCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
| | - Chenhao Bu
- Beijing Advanced Innovation Center for Tree Breeding by Molecular DesignBeijing Forestry UniversityBeijingChina
- National Engineering Laboratory for Tree BreedingCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental PlantsCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
| | - Dong Ci
- Beijing Advanced Innovation Center for Tree Breeding by Molecular DesignBeijing Forestry UniversityBeijingChina
- National Engineering Laboratory for Tree BreedingCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental PlantsCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
| | - Min Tian
- Beijing Advanced Innovation Center for Tree Breeding by Molecular DesignBeijing Forestry UniversityBeijingChina
- National Engineering Laboratory for Tree BreedingCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental PlantsCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
| | - Deqiang Zhang
- Beijing Advanced Innovation Center for Tree Breeding by Molecular DesignBeijing Forestry UniversityBeijingChina
- National Engineering Laboratory for Tree BreedingCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental PlantsCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijingChina
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10
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Belotserkovskii BP, Tornaletti S, D'Souza AD, Hanawalt PC. R-loop generation during transcription: Formation, processing and cellular outcomes. DNA Repair (Amst) 2018; 71:69-81. [PMID: 30190235 PMCID: PMC6340742 DOI: 10.1016/j.dnarep.2018.08.009] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
R-loops are structures consisting of an RNA-DNA duplex and an unpaired DNA strand. They can form during transcription upon nascent RNA "threadback" invasion into the DNA duplex to displace the non-template strand. Although R-loops occur naturally in all kingdoms of life and serve regulatory roles, they are often deleterious and can cause genomic instability. Of particular importance are the disastrous consequences when replication forks or transcription complexes collide with R-loops. The appropriate processing of R-loops is essential to avoid a number of human neurodegenerative and other clinical disorders. We provide a perspective on mechanistic aspects of R-loop formation and their resolution learned from studies in model systems. This should contribute to improved understanding of R-loop biological functions and enable their practical applications. We propose the novel employment of artificially-generated stable R-loops to selectively inactivate tumor cells.
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Affiliation(s)
- Boris P Belotserkovskii
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305-5020, United States
| | - Silvia Tornaletti
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305-5020, United States
| | - Alicia D D'Souza
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305-5020, United States
| | - Philip C Hanawalt
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305-5020, United States.
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11
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Halász L, Karányi Z, Boros-Oláh B, Kuik-Rózsa T, Sipos É, Nagy É, Mosolygó-L Á, Mázló A, Rajnavölgyi É, Halmos G, Székvölgyi L. RNA-DNA hybrid (R-loop) immunoprecipitation mapping: an analytical workflow to evaluate inherent biases. Genome Res 2017; 27:1063-1073. [PMID: 28341774 PMCID: PMC5453320 DOI: 10.1101/gr.219394.116] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 03/23/2017] [Indexed: 12/16/2022]
Abstract
The impact of R-loops on the physiology and pathology of chromosomes has been demonstrated extensively by chromatin biology research. The progress in this field has been driven by technological advancement of R-loop mapping methods that largely relied on a single approach, DNA-RNA immunoprecipitation (DRIP). Most of the DRIP protocols use the experimental design that was developed by a few laboratories, without paying attention to the potential caveats that might affect the outcome of RNA-DNA hybrid mapping. To assess the accuracy and utility of this technology, we pursued an analytical approach to estimate inherent biases and errors in the DRIP protocol. By performing DRIP-sequencing, qPCR, and receiver operator characteristic (ROC) analysis, we tested the effect of formaldehyde fixation, cell lysis temperature, mode of genome fragmentation, and removal of free RNA on the efficacy of RNA-DNA hybrid detection and implemented workflows that were able to distinguish complex and weak DRIP signals in a noisy background with high confidence. We also show that some of the workflows perform poorly and generate random answers. Furthermore, we found that the most commonly used genome fragmentation method (restriction enzyme digestion) led to the overrepresentation of lengthy DRIP fragments over coding ORFs, and this bias was enhanced at the first exons. Biased genome sampling severely compromised mapping resolution and prevented the assignment of precise biological function to a significant fraction of R-loops. The revised workflow presented herein is established and optimized using objective ROC analyses and provides reproducible and highly specific RNA-DNA hybrid detection.
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Affiliation(s)
- László Halász
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Zsolt Karányi
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Internal Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Beáta Boros-Oláh
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Tímea Kuik-Rózsa
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Éva Sipos
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biopharmacy, University of Debrecen, 4032 Debrecen, Hungary
| | - Éva Nagy
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Ágnes Mosolygó-L
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Anett Mázló
- Department of Immunology, University of Debrecen, 4032 Debrecen, Hungary
| | - Éva Rajnavölgyi
- Department of Immunology, University of Debrecen, 4032 Debrecen, Hungary
| | - Gábor Halmos
- Department of Biopharmacy, University of Debrecen, 4032 Debrecen, Hungary
| | - Lóránt Székvölgyi
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
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12
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Replication Fork Protection Factors Controlling R-Loop Bypass and Suppression. Genes (Basel) 2017; 8:genes8010033. [PMID: 28098815 PMCID: PMC5295027 DOI: 10.3390/genes8010033] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/02/2017] [Accepted: 01/09/2017] [Indexed: 12/17/2022] Open
Abstract
Replication–transcription conflicts have been a well-studied source of genome instability for many years and have frequently been linked to defects in RNA processing. However, recent characterization of replication fork-associated proteins has revealed that defects in fork protection can directly or indirectly stabilize R-loop structures in the genome and promote transcription–replication conflicts that lead to genome instability. Defects in essential DNA replication-associated activities like topoisomerase, or the minichromosome maintenance (MCM) helicase complex, as well as fork-associated protection factors like the Fanconi anemia pathway, both appear to mitigate transcription–replication conflicts. Here, we will highlight recent advances that support the concept that normal and robust replisome function itself is a key component of mitigating R-loop coupled genome instability.
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Abstract
Plants must adapt to multiple biotic and abiotic stresses ; thus, sensing and responding to environmental signals is imperative for their survival. Moreover, understanding these responses is imperative for efforts to improve plant yield and consistency. Regulation of transcript levels is a key aspect of the plant response to environmental signals. Long noncoding RNAs (lncRNAs) have gained widespread attention in recent years with the advance of high-throughput sequencing technologies. As important biological regulators, lncRNAs have been implicated in a wide range of developmental processes and diseases in animals. However, knowledge of the role that lncRNAs play in plant stress tolerance remains limited. Here, we review recent studies on the identification, characteristics, classification, and biological functions of lncRNAs in response to various stresses, including bacterial pathogens, excess light, drought, salinity, hypoxia, extreme temperatures, and nitrogen/phosphate deficiency. We also discuss possible directions for future research.
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Usdin K, Kumari D. Repeat-mediated epigenetic dysregulation of the FMR1 gene in the fragile X-related disorders. Front Genet 2015; 6:192. [PMID: 26089834 PMCID: PMC4452891 DOI: 10.3389/fgene.2015.00192] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/13/2015] [Indexed: 12/13/2022] Open
Abstract
The fragile X-related disorders are members of the Repeat Expansion Diseases, a group of genetic conditions resulting from an expansion in the size of a tandem repeat tract at a specific genetic locus. The repeat responsible for disease pathology in the fragile X-related disorders is CGG/CCG and the repeat tract is located in the 5′ UTR of the FMR1 gene, whose protein product FMRP, is important for the proper translation of dendritic mRNAs in response to synaptic activation. There are two different pathological FMR1 allele classes that are distinguished only by the number of repeats. Premutation alleles have 55–200 repeats and confer risk of fragile X-associated tremor/ataxia syndrome and fragile X-associated primary ovarian insufficiency. Full mutation alleles on the other hand have >200 repeats and result in fragile X syndrome, a disorder that affects learning and behavior. Different symptoms are seen in carriers of premutation and full mutation alleles because the repeat number has paradoxical effects on gene expression: Epigenetic changes increase transcription from premutation alleles and decrease transcription from full mutation alleles. This review will cover what is currently known about the mechanisms responsible for these changes in FMR1 expression and how they may relate to other Repeat Expansion Diseases that also show repeat-mediated changes in gene expression.
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Affiliation(s)
- Karen Usdin
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health , Bethesda, MD, USA
| | - Daman Kumari
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health , Bethesda, MD, USA
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15
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Liu J, Wang H, Chua NH. Long noncoding RNA transcriptome of plants. PLANT BIOTECHNOLOGY JOURNAL 2015; 13:319-28. [PMID: 25615265 DOI: 10.1111/pbi.12336] [Citation(s) in RCA: 169] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/09/2014] [Accepted: 12/16/2014] [Indexed: 05/20/2023]
Abstract
Since their discovery more than two decades ago, animal long noncoding RNAs (lncRNAs) have emerged as important regulators of many biological processes. Recently, a large number of lncRNAs have also been identified in higher plants, and here, we review their identification, classification and known regulatory functions in various developmental events and stress responses. Knowledge gained from a deeper understanding of this special group of noncoding RNAs may lead to biotechnological improvement of crops. Some possible examples in this direction are discussed.
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Affiliation(s)
- Jun Liu
- Laboratory of Plant Molecular Biology, The Rockefeller University, New York, NY, USA
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16
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Chan YA, Aristizabal MJ, Lu PYT, Luo Z, Hamza A, Kobor MS, Stirling PC, Hieter P. Genome-wide profiling of yeast DNA:RNA hybrid prone sites with DRIP-chip. PLoS Genet 2014; 10:e1004288. [PMID: 24743342 PMCID: PMC3990523 DOI: 10.1371/journal.pgen.1004288] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 02/21/2014] [Indexed: 12/17/2022] Open
Abstract
DNA:RNA hybrid formation is emerging as a significant cause of genome instability in biological systems ranging from bacteria to mammals. Here we describe the genome-wide distribution of DNA:RNA hybrid prone loci in Saccharomyces cerevisiae by DNA:RNA immunoprecipitation (DRIP) followed by hybridization on tiling microarray. These profiles show that DNA:RNA hybrids preferentially accumulated at rDNA, Ty1 and Ty2 transposons, telomeric repeat regions and a subset of open reading frames (ORFs). The latter are generally highly transcribed and have high GC content. Interestingly, significant DNA:RNA hybrid enrichment was also detected at genes associated with antisense transcripts. The expression of antisense-associated genes was also significantly altered upon overexpression of RNase H, which degrades the RNA in hybrids. Finally, we uncover mutant-specific differences in the DRIP profiles of a Sen1 helicase mutant, RNase H deletion mutant and Hpr1 THO complex mutant compared to wild type, suggesting different roles for these proteins in DNA:RNA hybrid biology. Our profiles of DNA:RNA hybrid prone loci provide a resource for understanding the properties of hybrid-forming regions in vivo, extend our knowledge of hybrid-mitigating enzymes, and contribute to models of antisense-mediated gene regulation. A summary of this paper was presented at the 26th International Conference on Yeast Genetics and Molecular Biology, August 2013.
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Affiliation(s)
- Yujia A. Chan
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
| | - Maria J. Aristizabal
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, Canada
| | - Phoebe Y. T. Lu
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, Canada
| | - Zongli Luo
- Wine Research Centre, University of British Columbia, Vancouver, Canada
| | - Akil Hamza
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
| | - Michael S. Kobor
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Peter C. Stirling
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
- * E-mail: (PCS); (PH)
| | - Philip Hieter
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
- * E-mail: (PCS); (PH)
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