101
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102
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Chien T, Weng YT, Chang SY, Lai HL, Chiu FL, Kuo HC, Chuang DM, Chern Y. GSK3β negatively regulates TRAX, a scaffold protein implicated in mental disorders, for NHEJ-mediated DNA repair in neurons. Mol Psychiatry 2018; 23:2375-2390. [PMID: 29298990 PMCID: PMC6294740 DOI: 10.1038/s41380-017-0007-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/28/2017] [Accepted: 10/30/2017] [Indexed: 12/27/2022]
Abstract
Translin-associated protein X (TRAX) is a scaffold protein with various functions and has been associated with mental illnesses, including schizophrenia. We have previously demonstrated that TRAX interacts with a Gsα protein-coupled receptor, the A2A adenosine receptor (A2AR), and mediates the function of this receptor in neuritogenesis. In addition, stimulation of the A2AR markedly ameliorates DNA damage evoked by elevated oxidative stress in neurons derived from induced pluripotent stem cells (iPSCs). Here, we report that glycogen synthase kinase 3 beta (GSK3β) and disrupted-in-schizophrenia 1 (DISC1) are two novel interacting proteins of TRAX. We present evidence to suggest that the stimulation of A2AR markedly facilitated DNA repair through the TRAX/DISC1/GSK3β complex in a rat neuronal cell line (PC12), primary mouse neurons, and human medium spiny neurons derived from iPSCs. A2AR stimulation led to the inhibition of GSK3β, thus dissociating the TRAX/DISC1/GSK3β complex and facilitating the non-homologous end-joining pathway (NHEJ) by enhancing the activation of a DNA-dependent protein kinase via phosphorylation at Thr2609. Similarly, pharmacological inhibition of GSK3β by SB216763 also facilitated the TRAX-mediated repair of oxidative DNA damage. Collectively, GSK3β binds with TRAX and negatively affects its ability to facilitate NHEJ repair. The suppression of GSK3β by A2AR activation or a GSK3β inhibitor releases TRAX for the repair of oxidative DNA damage. Our findings shed new light on the molecular mechanisms underlying diseases associated with DNA damage and provides a novel target (i.e., the TRAX/DISC1/GSK3β complex) for future therapeutic development for mental disorders.
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Affiliation(s)
- Ting Chien
- 0000 0004 0634 0356grid.260565.2Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan ,0000 0004 0633 7958grid.482251.8Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yu-Ting Weng
- 0000 0004 0633 7958grid.482251.8Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan ,0000 0001 2287 1366grid.28665.3fProgram in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan
| | - Shu-Yung Chang
- 0000 0004 0633 7958grid.482251.8Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan ,0000 0001 0425 5914grid.260770.4Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Hsing-Lin Lai
- 0000 0004 0633 7958grid.482251.8Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Feng-Lan Chiu
- 0000 0001 2287 1366grid.28665.3fInstitute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Hung-Chih Kuo
- 0000 0001 2287 1366grid.28665.3fInstitute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - De-Maw Chuang
- 0000 0004 0464 0574grid.416868.5Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA
| | - Yijuang Chern
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan. .,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan. .,Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan. .,Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan.
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103
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Failure to Inactivate Nuclear GSK3β by Ser 389-Phosphorylation Leads to Focal Neuronal Death and Prolonged Fear Response. Neuropsychopharmacology 2018; 43:393-405. [PMID: 28832021 PMCID: PMC5729567 DOI: 10.1038/npp.2017.187] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 07/25/2017] [Accepted: 08/17/2017] [Indexed: 12/19/2022]
Abstract
GSK3β plays an essential role in promoting cell death and is emerging as a potential target for neurological diseases. Understanding the mechanisms that control neuronal GSK3β is critical. A ubiquitous mechanism to repress GSK3β involves Akt-mediated phosphorylation of Ser9. Here we show that phosphorylation of GSK3β on Ser389 mediated by p38 MAPK specifically inactivates nuclear GSK3β in the cortex and hippocampus. Using GSK3β Ser389 to Ala mutant mice, we show that failure to inactivate nuclear GSK3β by Ser389 phosphorylation causes neuronal cell death in subregions of the hippocampus and cortex. Although this focal neuronal death does not impact anxiety/depression-like behavior or hippocampal-dependent spatial learning, it leads to an amplified and prolonged fear response. This phenotype is consistent with some aspects of post-traumatic stress disorder (PTSD). Our studies indicate that inactivation of nuclear GSK3β by Ser389 phosphorylation plays a key role in fear response, revealing new potential therapeutic approaches to target PTSD.
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104
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Yang Z, Price NE, Johnson KM, Wang Y, Gates KS. Interstrand cross-links arising from strand breaks at true abasic sites in duplex DNA. Nucleic Acids Res 2017; 45:6275-6283. [PMID: 28531327 PMCID: PMC5499897 DOI: 10.1093/nar/gkx394] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 05/02/2017] [Indexed: 01/04/2023] Open
Abstract
Interstrand cross-links are exceptionally bioactive DNA lesions. Endogenous generation of interstrand cross-links in genomic DNA may contribute to aging, neurodegeneration, and cancer. Abasic (Ap) sites are common lesions in genomic DNA that readily undergo spontaneous and amine-catalyzed strand cleavage reactions that generate a 2,3-didehydro-2,3-dideoxyribose sugar remnant (3’ddR5p) at the 3’-terminus of the strand break. Interestingly, this strand scission process leaves an electrophilic α,β-unsaturated aldehyde residue embedded within the resulting nicked duplex. Here we present evidence that 3’ddR5p derivatives generated by spermine-catalyzed strand cleavage at Ap sites in duplex DNA can react with adenine residues on the opposing strand to generate a complex lesion consisting of an interstrand cross-link adjacent to a strand break. The cross-link blocks DNA replication by ϕ29 DNA polymerase, a highly processive polymerase enzyme that couples synthesis with strand displacement. This suggests that 3’ddR5p-derived cross-links have the potential to block critical cellular DNA transactions that require strand separation. LC-MS/MS methods developed herein provide powerful tools for studying the occurrence and properties of these cross-links in biochemical and biological systems.
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Affiliation(s)
- Zhiyu Yang
- Department of Chemistry, University of Missouri, 125 Chemistry Building, Columbia, MO 65211, USA
| | - Nathan E Price
- Department of Chemistry, University of California, Riverside, CA 92521-0403, USA
| | - Kevin M Johnson
- Department of Chemistry, University of Missouri, 125 Chemistry Building, Columbia, MO 65211, USA
| | - Yinsheng Wang
- Department of Chemistry, University of California, Riverside, CA 92521-0403, USA
| | - Kent S Gates
- Department of Chemistry, University of Missouri, 125 Chemistry Building, Columbia, MO 65211, USA.,Department of Biochemistry, University of Missouri, 125 Chemistry Building, Columbia, MO 65211, USA
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105
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Lee KY, Im JS, Shibata E, Dutta A. ASF1a Promotes Non-homologous End Joining Repair by Facilitating Phosphorylation of MDC1 by ATM at Double-Strand Breaks. Mol Cell 2017; 68:61-75.e5. [PMID: 28943310 PMCID: PMC5743198 DOI: 10.1016/j.molcel.2017.08.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/17/2017] [Accepted: 08/22/2017] [Indexed: 11/15/2022]
Abstract
Double-strand breaks (DSBs) of DNA in eukaryotic cells are predominantly repaired by non-homologous end joining (NHEJ). The histone chaperone anti-silencing factor 1a (ASF1a) interacts with MDC1 and is recruited to sites of DSBs to facilitate the interaction of phospho-ATM with MDC1 and phosphorylation of MDC1, which are required for the recruitment of RNF8/RNF168 histone ubiquitin ligases. Thus, ASF1a deficiency reduces histone ubiquitination at DSBs, decreasing the recruitment of 53BP1, and decreases NHEJ, rendering cells more sensitive to DSBs. This role of ASF1a in DSB repair cannot be provided by the closely related ASF1b and does not require its histone chaperone activity. Homozygous deletion of ASF1A is seen in 10%-15% of certain cancers, suggesting that loss of NHEJ may be selected in some malignancies and that the deletion can be used as a molecular biomarker for cancers susceptible to radiotherapy or to DSB-inducing chemotherapy.
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Affiliation(s)
- Kyung Yong Lee
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22901, USA
| | - Jun-Sub Im
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22901, USA
| | - Etsuko Shibata
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22901, USA
| | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22901, USA.
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106
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Seifert BA, Dejosez M, Zwaka TP. Ronin influences the DNA damage response in pluripotent stem cells. Stem Cell Res 2017; 23:98-104. [PMID: 28715716 DOI: 10.1016/j.scr.2017.06.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 06/20/2017] [Accepted: 06/29/2017] [Indexed: 12/12/2022] Open
Abstract
Early mammalian embryonic cells must maintain a particularly robust DNA repair system, as mutations at this developmental point have detrimental consequences for the organism. How the repair system can be tuned to fulfill such elevated requirements is largely unknown, but it may involve transcriptional regulation. Ronin (Thap11) is a transcriptional regulator responsible for vital programs in pluripotent cells. Here, we report that this protein also modulates the DNA damage response of such cells. We show that conditional Ronin knockout sensitizes embryonic stem cells (ESCs) to UV-C-induced DNA damage in association with Atr pathway activation and G2/M arrest. Ronin binds to and regulates the genes encoding several DNA repair factors, including Gtf2h4 and Rad18, providing a potential mechanism for this phenotype. Our results suggest that the unique DNA repair requirements of the early embryo are not met by a static system, but rather via highly regulated processes.
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Affiliation(s)
- Bryce A Seifert
- Graduate Program in Molecular and Human Genetics at Baylor College of Medicine, Houston, TX 77030, USA.
| | - Marion Dejosez
- Huffington Center for Cell-Based Research in Parkinson's Disease, Black Family Stem Cell Institute, Department of Cell, Developmental & Regenerative Biology, Graduate School of Biomedical Sciences, New York, NY 10029, USA.
| | - Thomas P Zwaka
- Huffington Center for Cell-Based Research in Parkinson's Disease, Black Family Stem Cell Institute, Department of Cell, Developmental & Regenerative Biology, Graduate School of Biomedical Sciences, New York, NY 10029, USA.
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107
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Abstract
Multiple DNA repair pathways maintain genome stability and ensure that DNA remains essentially unchanged over the life of a cell. Various human diseases occur if DNA repair is compromised, and most of these impact the nervous system, in some cases exclusively. However, it is often unclear what specific endogenous damage underpins disease pathology. Generally, the types of causative DNA damage are associated with replication, transcription, or oxidative metabolism; other direct sources of endogenous lesions may arise from aberrant topoisomerase activity or ribonucleotide incorporation into DNA. This review focuses on the etiology of DNA damage in the nervous system and the genome stability pathways that prevent human neurologic disease.
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Affiliation(s)
- Peter J McKinnon
- Department of Genetics, St Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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108
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Abstract
Transcription-coupled DNA repair (TCR) acts on lesions in the transcribed strand of active genes. Helix distorting adducts and other forms of DNA damage often interfere with the progression of the transcription apparatus. Prolonged stalling of RNA polymerase can promote genome instability and also induce cell cycle arrest and apoptosis. These generally unfavorable events are counteracted by RNA polymerase-mediated recruitment of specific proteins to the sites of DNA damage to perform TCR and eventually restore transcription. In this perspective we discuss the decision-making process to employ TCR and we elucidate the intricate biochemical pathways leading to TCR in E. coli and human cells.
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Affiliation(s)
- Bibhusita Pani
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Evgeny Nudler
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA.
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109
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Abbotts R, Wilson DM. Coordination of DNA single strand break repair. Free Radic Biol Med 2017; 107:228-244. [PMID: 27890643 PMCID: PMC5443707 DOI: 10.1016/j.freeradbiomed.2016.11.039] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/21/2016] [Accepted: 11/23/2016] [Indexed: 12/28/2022]
Abstract
The genetic material of all organisms is susceptible to modification. In some instances, these changes are programmed, such as the formation of DNA double strand breaks during meiotic recombination to generate gamete variety or class switch recombination to create antibody diversity. However, in most cases, genomic damage is potentially harmful to the health of the organism, contributing to disease and aging by promoting deleterious cellular outcomes. A proportion of DNA modifications are caused by exogenous agents, both physical (namely ultraviolet sunlight and ionizing radiation) and chemical (such as benzopyrene, alkylating agents, platinum compounds and psoralens), which can produce numerous forms of DNA damage, including a range of "simple" and helix-distorting base lesions, abasic sites, crosslinks and various types of phosphodiester strand breaks. More significant in terms of frequency are endogenous mechanisms of modification, which include hydrolytic disintegration of DNA chemical bonds, attack by reactive oxygen species and other byproducts of normal cellular metabolism, or incomplete or necessary enzymatic reactions (such as topoisomerases or repair nucleases). Both exogenous and endogenous mechanisms are associated with a high risk of single strand breakage, either produced directly or generated as intermediates of DNA repair. This review will focus upon the creation, consequences and resolution of single strand breaks, with a particular focus on two major coordinating repair proteins: poly(ADP-ribose) polymerase 1 (PARP1) and X-ray repair cross-complementing protein 1 (XRCC1).
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Affiliation(s)
- Rachel Abbotts
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - David M Wilson
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.
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110
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Wu Q, Allouch A, Martins I, Brenner C, Modjtahedi N, Deutsch E, Perfettini JL. Modulating Both Tumor Cell Death and Innate Immunity Is Essential for Improving Radiation Therapy Effectiveness. Front Immunol 2017; 8:613. [PMID: 28603525 PMCID: PMC5445662 DOI: 10.3389/fimmu.2017.00613] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 05/09/2017] [Indexed: 12/17/2022] Open
Abstract
Radiation therapy is one of the cornerstones of cancer treatment. In tumor cells, exposure to ionizing radiation (IR) provokes DNA damages that trigger various forms of cell death such as apoptosis, necrosis, autophagic cell death, and mitotic catastrophe. IR can also induce cellular senescence that could serve as an additional antitumor barrier in a context-dependent manner. Moreover, accumulating evidence has demonstrated that IR interacts profoundly with tumor-infiltrating immune cells, which cooperatively drive treatment outcomes. Recent preclinical and clinical successes due to the combination of radiation therapy and immune checkpoint blockade have underscored the need for a better understanding of the interplay between radiation therapy and the immune system. In this review, we will present an overview of cell death modalities induced by IR, summarize the immunogenic properties of irradiated cancer cells, and discuss the biological consequences of IR on innate immune cell functions, with a particular attention on dendritic cells, macrophages, and NK cells. Finally, we will discuss their potential applications in cancer treatment.
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Affiliation(s)
- Qiuji Wu
- Cell Death and Aging Team, Gustave Roussy Cancer Campus, Villejuif, France.,Laboratory of Molecular Radiotherapy, INSERM U1030, Gustave Roussy Cancer Campus, Villejuif, France.,Gustave Roussy Cancer Campus, Villejuif, France.,Université Paris Saclay, Villejuif, France.,Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Awatef Allouch
- Cell Death and Aging Team, Gustave Roussy Cancer Campus, Villejuif, France.,Laboratory of Molecular Radiotherapy, INSERM U1030, Gustave Roussy Cancer Campus, Villejuif, France.,Gustave Roussy Cancer Campus, Villejuif, France.,Université Paris Saclay, Villejuif, France
| | - Isabelle Martins
- Cell Death and Aging Team, Gustave Roussy Cancer Campus, Villejuif, France.,Laboratory of Molecular Radiotherapy, INSERM U1030, Gustave Roussy Cancer Campus, Villejuif, France.,Gustave Roussy Cancer Campus, Villejuif, France.,Université Paris Saclay, Villejuif, France
| | - Catherine Brenner
- Laboratory of Signaling and Cardiovascular Pathophysiology, INSERM UMR-S 1180, Université Paris-Sud, Faculté de Pharmacie, Châtenay-Malabry, France
| | - Nazanine Modjtahedi
- Laboratory of Molecular Radiotherapy, INSERM U1030, Gustave Roussy Cancer Campus, Villejuif, France.,Gustave Roussy Cancer Campus, Villejuif, France.,Université Paris Saclay, Villejuif, France
| | - Eric Deutsch
- Laboratory of Molecular Radiotherapy, INSERM U1030, Gustave Roussy Cancer Campus, Villejuif, France.,Gustave Roussy Cancer Campus, Villejuif, France.,Université Paris Saclay, Villejuif, France
| | - Jean-Luc Perfettini
- Cell Death and Aging Team, Gustave Roussy Cancer Campus, Villejuif, France.,Laboratory of Molecular Radiotherapy, INSERM U1030, Gustave Roussy Cancer Campus, Villejuif, France.,Gustave Roussy Cancer Campus, Villejuif, France.,Université Paris Saclay, Villejuif, France
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111
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Chen HR, Juan HC, Wong YH, Tsai JW, Fann MJ. Cdk12 Regulates Neurogenesis and Late-Arising Neuronal Migration in the Developing Cerebral Cortex. Cereb Cortex 2017; 27:2289-2302. [PMID: 27073218 DOI: 10.1093/cercor/bhw081] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
DNA damage response (DDR) pathways are critical for ensuring that replication stress and various types of DNA lesion do not perturb production of neural cells during development. Cdk12 maintains genomic stability by regulating expression of DDR genes. Mutant mice in which Cdk12 is conditionally deleted in neural progenitor cells (NPCs) die after birth and exhibit microcephaly with a thinner cortical plate and an aberrant corpus callosum. We show that NPCs of mutant mice accumulate at G2 and M phase, and have lower expression of DDR genes, more DNA double-strand breaks and increased apoptosis. In addition to there being fewer neurons, there is misalignment of layers IV-II neurons and the presence of abnormal axonal tracts of these neurons, suggesting that Cdk12 is also required for the migration of late-arising cortical neurons. Using in utero electroporation, we demonstrate that the migrating mutant cells remain within the intermediate zone and fail to adopt a bipolar morphology. Overexpression of Cdk5 brings about a partially restoration of the neurons reaching layers IV-II in the mutant mice. Thus, Cdk12 is crucial to the repair of DNA damage during the proliferation of NPCs and is also central to the proper migration of late-arising neurons.
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Affiliation(s)
- Hong-Ru Chen
- Department of Life Sciences and Institute of Genome Sciences.,Brain Research Center
| | - Hsien-Chia Juan
- Department of Life Sciences and Institute of Genome Sciences
| | | | - Jin-Wu Tsai
- Brain Research Center.,Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan 11221, Republic of China
| | - Ming-Ji Fann
- Department of Life Sciences and Institute of Genome Sciences.,Brain Research Center
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112
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Woo HJ, Yu C, Kumar K, Reifman J. Large-scale interaction effects reveal missing heritability in schizophrenia, bipolar disorder and posttraumatic stress disorder. Transl Psychiatry 2017; 7:e1089. [PMID: 28398343 PMCID: PMC5416702 DOI: 10.1038/tp.2017.61] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 01/18/2017] [Accepted: 02/10/2017] [Indexed: 02/07/2023] Open
Abstract
Genetic susceptibility factors behind psychiatric disorders typically contribute small effects individually. A possible explanation for the missing heritability is that the effects of common variants are not only polygenic but also non-additive, appearing only when interactions within large groups are taken into account. Here, we tested this hypothesis for schizophrenia (SZ) and bipolar disorder (BP) disease risks, and identified genetic factors shared with posttraumatic stress disorder (PTSD). When considered independently, few single-nucleotide polymorphisms (SNPs) reached genome-wide significance. In contrast, when SNPs were selected in groups (containing up to thousands each) and the collective effects of all interactions were estimated, the association strength for SZ/BP rose dramatically with a combined sample size of 7187 cases and 8309 controls. We identified a large number of genes and pathways whose association was significant only when interaction effects were included. The gene with highest association was CSMD1, which encodes a negative regulator of complement activation. Pathways for glycosaminoglycan (GAG) synthesis exhibited strong association in multiple contexts. Taken together, highly associated pathways suggested a pathogenesis mechanism where maternal immune activation causes disruption of neurogenesis (compounded by impaired cell cycle, DNA repair and neuronal migration) and deficits in cortical interneurons, leading to symptoms triggered by synaptic pruning. Increased risks arise from GAG deficiencies causing complement activation and excessive microglial action. Analysis of PTSD data sets suggested an etiology common to SZ/BP: interneuron deficiency can also lead to impaired control of fear responses triggered by trauma. We additionally found PTSD risk factors affecting synaptic plasticity and fatty acid signaling, consistent with the fear extinction model. Our results suggest that much of the missing heritability of psychiatric disorders resides in non-additive interaction effects.
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Affiliation(s)
- H J Woo
- Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, MD, USA,Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, 504 Scott Street, Fort Detrick, MD 21702, USA. E-mail: or
| | - C Yu
- Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, MD, USA
| | - K Kumar
- Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, MD, USA
| | - J Reifman
- Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, MD, USA,Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, 504 Scott Street, Fort Detrick, MD 21702, USA. E-mail: or
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113
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Langie SAS, Cameron KM, Ficz G, Oxley D, Tomaszewski B, Gorniak JP, Maas LM, Godschalk RWL, van Schooten FJ, Reik W, von Zglinicki T, Mathers JC. The Ageing Brain: Effects on DNA Repair and DNA Methylation in Mice. Genes (Basel) 2017; 8:E75. [PMID: 28218666 PMCID: PMC5333064 DOI: 10.3390/genes8020075] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 02/02/2017] [Accepted: 02/07/2017] [Indexed: 12/15/2022] Open
Abstract
Base excision repair (BER) may become less effective with ageing resulting in accumulation of DNA lesions, genome instability and altered gene expression that contribute to age-related degenerative diseases. The brain is particularly vulnerable to the accumulation of DNA lesions; hence, proper functioning of DNA repair mechanisms is important for neuronal survival. Although the mechanism of age-related decline in DNA repair capacity is unknown, growing evidence suggests that epigenetic events (e.g., DNA methylation) contribute to the ageing process and may be functionally important through the regulation of the expression of DNA repair genes. We hypothesize that epigenetic mechanisms are involved in mediating the age-related decline in BER in the brain. Brains from male mice were isolated at 3-32 months of age. Pyrosequencing analyses revealed significantly increased Ogg1 methylation with ageing, which correlated inversely with Ogg1 expression. The reduced Ogg1 expression correlated with enhanced expression of methyl-CpG binding protein 2 and ten-eleven translocation enzyme 2. A significant inverse correlation between Neil1 methylation at CpG-site2 and expression was also observed. BER activity was significantly reduced and associated with increased 8-oxo-7,8-dihydro-2'-deoxyguanosine levels. These data indicate that Ogg1 and Neil1 expression can be epigenetically regulated, which may mediate the effects of ageing on DNA repair in the brain.
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Affiliation(s)
- Sabine A S Langie
- Centre for Ageing and Vitality, Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK.
| | - Kerry M Cameron
- The Ageing Biology Centre and Institute for Cell and Molecular Biology, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK.
| | - Gabriella Ficz
- Barts Cancer Institute, Queen Mary University, London EC1M 6BQ, UK.
| | - David Oxley
- Mass Spectrometry Laboratory, Babraham Institute, Cambridge CB22 3AT, UK.
| | - Bartłomiej Tomaszewski
- Centre for Ageing and Vitality, Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK.
| | - Joanna P Gorniak
- Centre for Ageing and Vitality, Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK.
| | - Lou M Maas
- Department of Pharmacology & Toxicology, School for Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, 6200 MD Maastricht, The Netherlands.
| | - Roger W L Godschalk
- Department of Pharmacology & Toxicology, School for Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, 6200 MD Maastricht, The Netherlands.
| | - Frederik J van Schooten
- Department of Pharmacology & Toxicology, School for Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, 6200 MD Maastricht, The Netherlands.
| | - Wolf Reik
- Epigenetics Programme, Babraham Institute, Cambridge CB22 3AT, UK.
- Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
| | - Thomas von Zglinicki
- The Ageing Biology Centre and Institute for Cell and Molecular Biology, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK.
| | - John C Mathers
- Centre for Ageing and Vitality, Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK.
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114
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Li C, Dong Y, Chen D, Xie Z, Zhang Y. Mild Hypothermia Attenuates the Anesthetic Isoflurane-Induced Cytotoxicity. Front Cell Neurosci 2017; 11:15. [PMID: 28228717 PMCID: PMC5296297 DOI: 10.3389/fncel.2017.00015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/18/2017] [Indexed: 02/05/2023] Open
Abstract
The commonly used inhalation anesthetic isoflurane has been reported to induce DNA damage and cytotoxicity. However, the methods to attenuate these effects remain largely to be determined. Mild hypothermia has neuroprotective effects. We therefore set out to assess whether mild hypothermia could protect the isoflurane-induced DNA damage and cytotoxicity. Moreover, we investigated the underlying mechanisms by assessing the effects of mild hypothermia on the isoflurane-induced changes in ATP levels. H4 human neuroglioma cells were treated with 2% isoflurane for 3 or 6 h with and without mild hypothermia (35°C). We assessed the cell viability by using 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) and lactate dehydrogenase (LDH) assay. We determined DNA damage by measuring levels of phosphorylation of the histone protein H2A variant X at Ser139 (γH2A.X), the marker of DNA damage. We also measured ATP levels in the cells. Here we showed that the treatment with 2% isoflurane for 6 h induced cytotoxicity and DNA damage in the cells. Moreover, the treatment with 2% isoflurane for 3 h decreased ATP levels without inducing cytotoxicity. Mild hypothermia attenuated the isoflurane-induced cytotoxicity, DNA damage, and ATP reduction in the cells. Taken together, these data suggest that the isoflurane-induced reduction in ATP levels occurred before the isoflurane-induced cytotoxicity. Isoflurane may induce DNA damage and cause cytotoxicity through reducing ATP levels. Mild hypothermia would ameliorate isoflurane-induced DNA damage and cytotoxicity by attenuating the isoflurane-induced reduction in ATP levels. These pilot studies have established a system and will promote the future investigations of anesthesia neurotoxicity.
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Affiliation(s)
- Cheng Li
- Shanghai Tenth People's Hospital, Tongji University School of MedicineShanghai, China; Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical SchoolCharlestown, MA, USA
| | - Yuanlin Dong
- Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School Charlestown, MA, USA
| | - Dan Chen
- Shanghai Tenth People's Hospital, Tongji University School of MedicineShanghai, China; Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical SchoolCharlestown, MA, USA
| | - Zhongcong Xie
- Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School Charlestown, MA, USA
| | - Yiying Zhang
- Shanghai Tenth People's Hospital, Tongji University School of MedicineShanghai, China; Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical SchoolCharlestown, MA, USA
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Pai CC, Kearsey SE. A Critical Balance: dNTPs and the Maintenance of Genome Stability. Genes (Basel) 2017; 8:genes8020057. [PMID: 28146119 PMCID: PMC5333046 DOI: 10.3390/genes8020057] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 01/24/2017] [Indexed: 01/14/2023] Open
Abstract
A crucial factor in maintaining genome stability is establishing deoxynucleoside triphosphate (dNTP) levels within a range that is optimal for chromosomal replication. Since DNA replication is relevant to a wide range of other chromosomal activities, these may all be directly or indirectly affected when dNTP concentrations deviate from a physiologically normal range. The importance of understanding these consequences is relevant to genetic disorders that disturb dNTP levels, and strategies that inhibit dNTP synthesis in cancer chemotherapy and for treatment of other disorders. We review here how abnormal dNTP levels affect DNA replication and discuss the consequences for genome stability.
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Affiliation(s)
- Chen-Chun Pai
- CRUK-MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK.
| | - Stephen E Kearsey
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
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Zhang J, Shim G, de Toledo SM, Azzam EI. The Translationally Controlled Tumor Protein and the Cellular Response to Ionizing Radiation-Induced DNA Damage. Results Probl Cell Differ 2017; 64:227-253. [DOI: 10.1007/978-3-319-67591-6_12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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117
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Jones L, Houlden H, Tabrizi SJ. DNA repair in the trinucleotide repeat disorders. Lancet Neurol 2017; 16:88-96. [PMID: 27979358 DOI: 10.1016/s1474-4422(16)30350-7] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 09/22/2016] [Accepted: 10/27/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND Inherited diseases caused by unstable repeated DNA sequences are rare, but together represent a substantial cause of morbidity. Trinucleotide repeat disorders are severe, usually life-shortening, neurological disorders caused by nucleotide expansions, and most have no disease-modifying treatments. Longer repeat expansions are associated with genetic anticipation (ie, earlier disease onset in successive generations), although the differences in age at onset are not entirely accounted for by repeat length. Such phenotypic variation within disorders implies the existence of additional modifying factors in pathways that can potentially be modulated to treat disease. RECENT DEVELOPMENTS A genome-wide association study detected genetic modifiers of age at onset in Huntington's disease. Similar findings were seen in the spinocerebellar ataxias, indicating an association between DNA damage-response and repair pathways and the age at onset of disease. These studies also suggest that a common genetic mechanism modulates age at onset across polyglutamine diseases and could extend to other repeat expansion disorders. Genetic defects in DNA repair underlie other neurodegenerative disorders (eg, ataxia-telangiectasia), and DNA double-strand breaks are crucial to the modulation of early gene expression, which provides a mechanistic link between DNA repair and neurodegeneration. Mismatch and base-excision repair are important in the somatic expansion of repeated sequences in mouse models of trinucleotide repeat disorders, and somatic expansion of the expanded CAG tract in HTT correlates with age at onset of Huntington's disease and other trinucleotide repeat disorders. WHERE NEXT?: To understand the common genetic architecture of trinucleotide repeat disorders and any further genetic susceptibilities in individual disorders, genetic analysis with increased numbers of variants and sample sizes is needed, followed by sequencing approaches to define the phenotype-modifying variants. The findings must then be translated into cell biology analyses to elucidate the mechanisms through which the genetic variants operate. Genes that have roles in the DNA damage response could underpin a common DNA repeat-based mechanism and provide new therapeutic targets (and hence therapeutics) in multiple trinucleotide repeat disorders.
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Affiliation(s)
- Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, UK.
| | - Henry Houlden
- Department of Molecular Neuroscience and MRC Centre for Neuromuscular Diseases, Institute of Neurology, Queen Square, London, UK
| | - Sarah J Tabrizi
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, Institute of Neurology, University College London, London, UK
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Hou Y, Song H, Croteau DL, Akbari M, Bohr VA. Genome instability in Alzheimer disease. Mech Ageing Dev 2017; 161:83-94. [PMID: 27105872 PMCID: PMC5195918 DOI: 10.1016/j.mad.2016.04.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/05/2016] [Accepted: 04/15/2016] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common form of dementia. Autosomal dominant, familial AD (fAD) is very rare and caused by mutations in amyloid precursor protein (APP), presenilin-1 (PSEN-1), and presenilin-2 (PSEN-2) genes. The pathogenesis of sporadic AD (sAD) is more complex and variants of several genes are associated with an increased lifetime risk of AD. Nuclear and mitochondrial DNA integrity is pivotal during neuronal development, maintenance and function. DNA damage and alterations in cellular DNA repair capacity have been implicated in the aging process and in age-associated neurodegenerative diseases, including AD. These findings are supported by research using animal models of AD and in DNA repair deficient animal models. In recent years, novel mechanisms linking DNA damage to neuronal dysfunction have been identified and have led to the development of noninvasive treatment strategies. Further investigations into the molecular mechanisms connecting DNA damage to AD pathology may help to develop novel treatment strategies for this debilitating disease. Here we provide an overview of the role of genome instability and DNA repair deficiency in AD pathology and discuss research strategies that include genome instability as a component.
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Affiliation(s)
- Yujun Hou
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Hyundong Song
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Mansour Akbari
- Center for Healthy Aging, SUND, University of Copenhagen, Denmark
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD 21224, USA.
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Karikkineth AC, Scheibye-Knudsen M, Fivenson E, Croteau DL, Bohr VA. Cockayne syndrome: Clinical features, model systems and pathways. Ageing Res Rev 2017; 33:3-17. [PMID: 27507608 PMCID: PMC5195851 DOI: 10.1016/j.arr.2016.08.002] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/29/2016] [Accepted: 08/04/2016] [Indexed: 12/12/2022]
Abstract
Cockayne syndrome (CS) is a disorder characterized by a variety of clinical features including cachectic dwarfism, severe neurological manifestations including microcephaly and cognitive deficits, pigmentary retinopathy, cataracts, sensorineural deafness, and ambulatory and feeding difficulties, leading to death by 12 years of age on average. It is an autosomal recessive disorder, with a prevalence of approximately 2.5 per million. There are several phenotypes (1-3) and two complementation groups (CSA and CSB), and CS overlaps with xeroderma pigmentosum (XP). It has been considered a progeria, and many of the clinical features resemble accelerated aging. As such, the study of CS affords an opportunity to better understand the underlying mechanisms of aging. The molecular basis of CS has traditionally been ascribed to defects in transcription and transcription-coupled nucleotide excision repair (TC-NER). However, recent work suggests that defects in base excision DNA repair and mitochondrial functions may also play key roles. This opens up the possibility for molecular interventions in CS, and by extrapolation, possibly in aging.
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Affiliation(s)
- Ajoy C Karikkineth
- Clinical Research Branch, National Institute on Aging, Baltimore, MD, USA
| | - Morten Scheibye-Knudsen
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD, USA; Department of Cellular and Molecular Medicine, University of Copenhagen, Denmark
| | - Elayne Fivenson
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD, USA
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD, USA.
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Rothblum-Oviatt C, Wright J, Lefton-Greif MA, McGrath-Morrow SA, Crawford TO, Lederman HM. Ataxia telangiectasia: a review. Orphanet J Rare Dis 2016; 11:159. [PMID: 27884168 PMCID: PMC5123280 DOI: 10.1186/s13023-016-0543-7] [Citation(s) in RCA: 355] [Impact Index Per Article: 44.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 11/16/2016] [Indexed: 12/15/2022] Open
Abstract
DEFINITION OF THE DISEASE Ataxia telangiectasia (A-T) is an autosomal recessive disorder primarily characterized by cerebellar degeneration, telangiectasia, immunodeficiency, cancer susceptibility and radiation sensitivity. A-T is often referred to as a genome instability or DNA damage response syndrome. EPIDEMIOLOGY The world-wide prevalence of A-T is estimated to be between 1 in 40,000 and 1 in 100,000 live births. CLINICAL DESCRIPTION A-T is a complex disorder with substantial variability in the severity of features between affected individuals, and at different ages. Neurological symptoms most often first appear in early childhood when children begin to sit or walk. They have immunological abnormalities including immunoglobulin and antibody deficiencies and lymphopenia. People with A-T have an increased predisposition for cancers, particularly of lymphoid origin. Pulmonary disease and problems with feeding, swallowing and nutrition are common, and there also may be dermatological and endocrine manifestations. ETIOLOGY A-T is caused by mutations in the ATM (Ataxia Telangiectasia, Mutated) gene which encodes a protein of the same name. The primary role of the ATM protein is coordination of cellular signaling pathways in response to DNA double strand breaks, oxidative stress and other genotoxic stress. DIAGNOSIS The diagnosis of A-T is usually suspected by the combination of neurologic clinical features (ataxia, abnormal control of eye movement, and postural instability) with one or more of the following which may vary in their appearance: telangiectasia, frequent sinopulmonary infections and specific laboratory abnormalities (e.g. IgA deficiency, lymphopenia especially affecting T lymphocytes and increased alpha-fetoprotein levels). Because certain neurological features may arise later, a diagnosis of A-T should be carefully considered for any ataxic child with an otherwise elusive diagnosis. A diagnosis of A-T can be confirmed by the finding of an absence or deficiency of the ATM protein or its kinase activity in cultured cell lines, and/or identification of the pathological mutations in the ATM gene. DIFFERENTIAL DIAGNOSIS There are several other neurologic and rare disorders that physicians must consider when diagnosing A-T and that can be confused with A-T. Differentiation of these various disorders is often possible with clinical features and selected laboratory tests, including gene sequencing. ANTENATAL DIAGNOSIS Antenatal diagnosis can be performed if the pathological ATM mutations in that family have been identified in an affected child. In the absence of identifying mutations, antenatal diagnosis can be made by haplotype analysis if an unambiguous diagnosis of the affected child has been made through clinical and laboratory findings and/or ATM protein analysis. GENETIC COUNSELING Genetic counseling can help family members of a patient with A-T understand when genetic testing for A-T is feasible, and how the test results should be interpreted. MANAGEMENT AND PROGNOSIS Treatment of the neurologic problems associated with A-T is symptomatic and supportive, as there are no treatments known to slow or stop the neurodegeneration. However, other manifestations of A-T, e.g. immunodeficiency, pulmonary disease, failure to thrive and diabetes can be treated effectively.
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Affiliation(s)
| | - Jennifer Wright
- The Ataxia Telangiectasia Clinical Center, Johns Hopkins Medical Institutions, Baltimore, Maryland USA
| | - Maureen A. Lefton-Greif
- The Ataxia Telangiectasia Clinical Center, Departments of Pediatrics and Pediatric Respiratory Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland USA
| | - Sharon A. McGrath-Morrow
- The Ataxia Telangiectasia Clinical Center, Departments of Pediatrics and Pediatric Respiratory Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland USA
| | - Thomas O. Crawford
- The Ataxia Telangiectasia Clinical Center, Departments of Pediatrics and Neurology, Johns Hopkins Medical Institutions, Baltimore, Maryland USA
| | - Howard M. Lederman
- The Ataxia Telangiectasia Clinical Center, Departments of Pediatrics, Medicine and Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland USA
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Antisense oligonucleotide-mediated exon skipping as a strategy to reduce proteolytic cleavage of ataxin-3. Sci Rep 2016; 6:35200. [PMID: 27731380 PMCID: PMC5059676 DOI: 10.1038/srep35200] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 09/27/2016] [Indexed: 12/04/2022] Open
Abstract
Spinocerebellar ataxia type-3 (SCA3) is a neurodegenerative disorder caused by a polyglutamine repeat expansion in the ataxin-3 protein. Cleavage of mutant ataxin-3 by proteolytic enzymes yields ataxin-3 fragments containing the polyglutamine stretch. These shorter ataxin-3 fragments are thought to be involved in SCA3 pathogenesis due to their increased cellular toxicity and their involvement in formation of the characteristic neuronal aggregates. As a strategy to prevent formation of toxic cleavage fragments, we investigated an antisense oligonucleotide-mediated modification of the ataxin-3 pre-mRNA through exon skipping of exon 8 and 9, resulting in the removal of a central 88 amino acid region of the ataxin-3 protein. This removed protein region contains several predicted cleavage sites and two ubiquitin-interacting motifs. In contrast to unmodified mutant ataxin-3, the internally truncated ataxin-3 protein did not give rise to potentially toxic cleavage fragments when incubated with caspases. In vitro experiments did not show cellular toxicity of the modified ataxin-3 protein. However, the modified protein was incapable of binding poly-ubiquitin chains, which may interfere with its normal deubiquitinating function. Low exon skipping efficiencies combined with reduction in important ataxin-3 protein functions suggest that skipping of exon 8 and 9 is not a viable therapeutic option for SCA3.
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122
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Gan L, Yang B, Mei H. The effect of iron dextran on the transcriptome of pig hippocampus. Genes Genomics 2016. [DOI: 10.1007/s13258-016-0469-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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123
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Wang H, Dharmalingam P, Vasquez V, Mitra J, Boldogh I, Rao KS, Kent TA, Mitra S, Hegde ML. Chronic oxidative damage together with genome repair deficiency in the neurons is a double whammy for neurodegeneration: Is damage response signaling a potential therapeutic target? Mech Ageing Dev 2016; 161:163-176. [PMID: 27663141 DOI: 10.1016/j.mad.2016.09.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 09/13/2016] [Accepted: 09/19/2016] [Indexed: 12/14/2022]
Abstract
A foremost challenge for the neurons, which are among the most oxygenated cells, is the genome damage caused by chronic exposure to endogenous reactive oxygen species (ROS), formed as cellular respiratory byproducts. Strong metabolic activity associated with high transcriptional levels in these long lived post-mitotic cells render them vulnerable to oxidative genome damage, including DNA strand breaks and mutagenic base lesions. There is growing evidence for the accumulation of unrepaired DNA lesions in the central nervous system (CNS) during accelerated aging and progressive neurodegeneration. Several germ line mutations in DNA repair or DNA damage response (DDR) signaling genes are uniquely manifested in the phenotype of neuronal dysfunction and are etiologically linked to many neurodegenerative disorders. Studies in our lab and elsewhere revealed that pro-oxidant metals, ROS and misfolded amyloidogenic proteins not only contribute to genome damage in CNS, but also impede their repair/DDR signaling leading to persistent damage accumulation, a common feature in sporadic neurodegeneration. Here, we have reviewed recent advances in our understanding of the etiological implications of DNA damage vs. repair imbalance, abnormal DDR signaling in triggering neurodegeneration and potential of DDR as a target for the amelioration of neurodegenerative diseases.
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Affiliation(s)
- Haibo Wang
- Department of Radiation Oncology, Houston Methodist Research Institute, Houston, TX 77030, USA; Houston Methodist Neurological Institute, Houston, TX 77030, USA
| | - Prakash Dharmalingam
- Department of Radiation Oncology, Houston Methodist Research Institute, Houston, TX 77030, USA; Houston Methodist Neurological Institute, Houston, TX 77030, USA
| | - Velmarini Vasquez
- Department of Radiation Oncology, Houston Methodist Research Institute, Houston, TX 77030, USA; Centre for Neuroscience, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), City of Knowledge, Panama City, Panama; Department of Biotechnology, Acharya Nagarjuna University, Guntur, AP, India; Houston Methodist Neurological Institute, Houston, TX 77030, USA
| | - Joy Mitra
- Department of Radiation Oncology, Houston Methodist Research Institute, Houston, TX 77030, USA; Houston Methodist Neurological Institute, Houston, TX 77030, USA
| | - Istvan Boldogh
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - K S Rao
- Centre for Neuroscience, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), City of Knowledge, Panama City, Panama
| | - Thomas A Kent
- Department of Neurology, Baylor College of Medicine and Center for Translational Research on Inflammatory Diseases Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX 77030, USA
| | - Sankar Mitra
- Department of Radiation Oncology, Houston Methodist Research Institute, Houston, TX 77030, USA; Weill Medical College of Cornell University, New York, USA
| | - Muralidhar L Hegde
- Department of Radiation Oncology, Houston Methodist Research Institute, Houston, TX 77030, USA; Houston Methodist Neurological Institute, Houston, TX 77030, USA; Weill Medical College of Cornell University, New York, USA.
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Abstract
Topoisomerases are unique enzymes that regulate torsional stress in DNA to enable essential genome functions, including DNA replication and transcription. Although all cells in an organism require topoisomerases to maintain normal function, the nervous system in particular shows a vital need for these enzymes. Indeed, a range of inherited human neurologic syndromes, including neurodegeneration, schizophrenia and intellectual impairment, are associated with aberrant topoisomerase function. Much remains unknown regarding the tissue-specific function of neural topoisomerases or the connections between these enzymes and disease aetiology. Precisely how topoisomerases regulate genome dynamics within the nervous system is therefore a crucial research question.
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125
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Shahrour MA, Nicolae CM, Edvardson S, Ashhab M, Galvan AM, Constantin D, Abu-Libdeh B, Moldovan GL, Elpeleg O. PARP10 deficiency manifests by severe developmental delay and DNA repair defect. Neurogenetics 2016; 17:227-232. [PMID: 27624574 DOI: 10.1007/s10048-016-0493-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 11/26/2022]
Abstract
DNA repair mechanisms such as nucleotide excision repair (NER) and translesion synthesis (TLS) are dependent on proliferating cell nuclear antigen (PCNA), a DNA polymerase accessory protein. Recently, homozygosity for p.Ser228Ile mutation in the PCNA gene was reported in patients with neurodegeneration and impaired NER. Using exome sequencing, we identified a homozygous deleterious mutation, c.648delAG, in the PARP10 gene, in a patient suffering from severe developmental delay. In agreement, PARP10 protein was absent from the patient cells. We have previously shown that PARP10 is recruited by PCNA to DNA damage sites and is required for DNA damage resistance. The patient cells were significantly more sensitive to hydroxyurea and UV-induced DNA damage than control cells, resulting in increased apoptosis, indicating DNA repair impairment in the patient cells. PARP10 deficiency joins the long list of DNA repair defects associated with neurodegenerative disorders, including ataxia telangiectasia, xeroderma pigmentosum, Cockayne syndrome, and the recently reported PCNA mutation.
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Affiliation(s)
| | - Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Simon Edvardson
- Pediatric Neurology Unit, Hadassah, Hebrew University Medical Center, Jerusalem, Israel
- Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center, Jerusalem, Israel
| | - Motee Ashhab
- Department of Pediatrics, Al-Makassed Islamic Hospital, Jerusalem, Israel
| | - Adri M Galvan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Daniel Constantin
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Bassam Abu-Libdeh
- Department of Pediatrics, Al-Makassed Islamic Hospital, Jerusalem, Israel
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
| | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center, Jerusalem, Israel.
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Martin LJ, Wong M. Enforced DNA repair enzymes rescue neurons from apoptosis induced by target deprivation and axotomy in mouse models of neurodegeneration. Mech Ageing Dev 2016; 161:149-162. [PMID: 27364693 DOI: 10.1016/j.mad.2016.06.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 06/23/2016] [Accepted: 06/26/2016] [Indexed: 02/06/2023]
Abstract
It is unknown whether DNA damage accumulation is an upstream instigator or secondary effect of the cell death process in different populations of adult postmitotic neurons in the central nervous system. In two different mouse models of injury-induced neurodegeneration characterized by relatively synchronous accumulation of mitochondria, oxidative stress, and DNA damage prior to neuronal apoptosis, we enforced the expression of human 8-oxoguanine DNA glycosylase (hOGG1) and human apurinic-apyrimidinic endonuclease-1/Ref1 (hAPE) using recombinant adenoviruses (Ad). Thalamic lateral geniculate neurons and lumbar spinal cord motor neurons were transduced by Ad-hOGG1 and Ad-hAPE injections into the occipital cortex and skeletal muscle, respectively, prior to their target deprivation- and axotomy-induced retrograde apoptosis. Enforced expression of hOGG1 and hAPE in thalamus and spinal cord was confirmed by western blotting and immunohistochemistry. In injured populations of neurons in thalamus and spinal cord, a DNA damage response (DDR) was registered, as shown by localization of phospho-activated p53, Rad17, and replication protein A-32 immunoreactivities, and this DDR was attenuated more effectively by enforced hAPE expression than by hOGG1 expression. Enforced expression of hOGG1 and hAPE significantly protected thalamic neurons and motor neurons from retrograde apoptosis induced by target deprivation and axotomy. We conclude that a DDR response is engaged pre-apoptotically in different types of injured mature CNS neurons and that DNA repair enzymes can regulate the survival of retrogradely dying neurons, suggesting that DNA damage and activation of DDR are upstream mechanisms for this form of adult neurodegeneration in vivo, thus identifying DNA repair as a therapeutic target for neuroprotection.
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Affiliation(s)
- Lee J Martin
- Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Pathobiology Graduate Training Program, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Margaret Wong
- Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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127
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Zhu S, Peng A. Non-homologous end joining repair in Xenopus egg extract. Sci Rep 2016; 6:27797. [PMID: 27324260 PMCID: PMC4914968 DOI: 10.1038/srep27797] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/25/2016] [Indexed: 11/09/2022] Open
Abstract
Non-homologous end joining (NHEJ) is a major DNA double-strand break (DSB) repair mechanism. We characterized here a series of plasmid-based DSB templates that were repaired in Xenopus egg extracts via the canonical, Ku-dependent NHEJ pathway. We showed that the template with compatible ends was efficiently repaired without end processing, in a manner that required the kinase activity of DNA-PKcs but not ATM. Moreover, non-compatible ends with blunt/3'-overhang, blunt/5'-overhang, and 3'-overhang/5'-overhang were predominantly repaired with fill-in and ligation without the removal of end nucleotides. In contrast, 3'-overhang/3'-overhang and 5'-overhang/5'-overhang templates were processed by resection of 3-5 bases and fill-in of 1-4 bases prior to end ligation. Therefore, the NHEJ machinery exhibited a strong preference for precise repair; the presence of neither non-compatible ends nor protruding single strand DNA sufficiently warranted the action of nucleases. ATM was required for the efficient repair of all non-compatible ends including those repaired without end processing by nucleases, suggesting its role beyond phosphorylation and regulation of Artemis. Finally, dephosphorylation of the 5'-overhang/3'-overhang template reduced the efficiency of DNA repair without increasing the risk of end resection, indicating that end protection via prompt end ligation is not the sole mechanism that suppresses the action of nucleases.
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Affiliation(s)
- Songli Zhu
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Aimin Peng
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
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128
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Ni C, Li C, Dong Y, Guo X, Zhang Y, Xie Z. Anesthetic Isoflurane Induces DNA Damage Through Oxidative Stress and p53 Pathway. Mol Neurobiol 2016; 54:3591-3605. [PMID: 27194299 DOI: 10.1007/s12035-016-9937-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Accepted: 05/10/2016] [Indexed: 02/05/2023]
Abstract
DNA damage is associated with aging and neurological disorders, including Alzheimer's disease. Isoflurane is a commonly used anesthetic. It remains largely unknown whether isoflurane induces DNA damage. Phosphorylation of the histone protein H2A variant X at Ser139 (γH2A.X) is a marker of DNA damage. We therefore set out to assess the effects of isoflurane on γH2A.X level in H4 human neuroglioma cells and in brain tissues of mice. Oxidative stress, caspase-activated DNase (CAD), and the p53 signaling pathway are involved in DNA damage. Thus, we determined the interaction of isoflurane with reactive oxygen species (ROS), CAD, and p53 to illustrate the underlying mechanisms. The cells were treated with 2 % isoflurane for 3 or 6 h. The mice were anesthetized with 1.4 % isoflurane for 2 h. Western blot, immunostaining and live cell fluorescence staining were used in the experiments. We showed that isoflurane increased levels of γH2A.X, cleaved caspase-3, and nucleus translocation of CAD and decreased levels of inhibitor of CAD (ICAD) and p53. Isoflurane enhanced the nucleus level of γH2A.X. Moreover, caspase inhibitor Z-VAD and ROS generation inhibitor N-acetyl-L-cysteine (NAC) attenuated the isoflurane-induced increase in γH2A.X level. However, NAC did not significantly alter the isoflurane-induced reduction in p53 level. Finally, p53 activator (actinomycin D) and inhibitor (pifithrin-α) attenuated and potentiated the isoflurane-induced increase in γH2A.X level, respectively. These findings suggest that isoflurane might induce DNA damage, as represented by increased γH2A.X level, via induction of oxidative stress and inhibition of the repair of DNA damage through the p53 signaling pathway.
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Affiliation(s)
- Cheng Ni
- Department of Anesthesiology, Peking University Third Hospital, 49 North Garden Rd., Haidian District, Beijing, 100191, China
- Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, 149 13th St., Room 4310, Charlestown, MA, 02129, USA
| | - Cheng Li
- Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, 149 13th St., Room 4310, Charlestown, MA, 02129, USA
- Department of Anesthesiology, Shanghai Tenth People's Hospital, Tongji University, Shanghai, 200072, China
| | - Yuanlin Dong
- Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, 149 13th St., Room 4310, Charlestown, MA, 02129, USA
| | - Xiangyang Guo
- Department of Anesthesiology, Peking University Third Hospital, 49 North Garden Rd., Haidian District, Beijing, 100191, China
| | - Yiying Zhang
- Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, 149 13th St., Room 4310, Charlestown, MA, 02129, USA
| | - Zhongcong Xie
- Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, 149 13th St., Room 4310, Charlestown, MA, 02129, USA.
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129
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Increased neuronal death and disturbed axonal growth in the Polμ-deficient mouse embryonic retina. Sci Rep 2016; 6:25928. [PMID: 27172884 PMCID: PMC4865816 DOI: 10.1038/srep25928] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/25/2016] [Indexed: 01/04/2023] Open
Abstract
Programmed cell death occurs naturally at different stages of neural development, including neurogenesis. The functional role of this early phase of neural cell death, which affects recently differentiated neurons among other cell types, remains undefined. Some mouse models defective in DNA double-strand break (DSB) repair present massive cell death during neural development, occasionally provoking embryonic lethality, while other organs and tissues remain unaffected. This suggests that DSBs occur frequently and selectively in the developing nervous system. We analyzed the embryonic retina of a mouse model deficient in the error-prone DNA polymerase μ (Polμ), a key component of the non-homologous end-joining (NHEJ) repair system. DNA DSBs were increased in the mutant mouse at embryonic day 13.5 (E13.5), as well as the incidence of cell death that affected young neurons, including retinal ganglion cells (RGCs). Polμ(-/-) mice also showed disturbed RGC axonal growth and navigation, and altered distribution of the axonal guidance molecules L1-CAM and Bravo (also known as Nr-CAM). These findings demonstrate that Polμ is necessary for proper retinal development, and support that the generation of DSBs and their repair via the NHEJ pathway are genuine processes involved in neural development.
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130
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Dumitrache LC, McKinnon PJ. Polynucleotide kinase-phosphatase (PNKP) mutations and neurologic disease. Mech Ageing Dev 2016; 161:121-129. [PMID: 27125728 DOI: 10.1016/j.mad.2016.04.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 04/12/2016] [Accepted: 04/24/2016] [Indexed: 12/30/2022]
Abstract
A variety of human neurologic diseases are caused by inherited defects in DNA repair. In many cases, these syndromes almost exclusively impact the nervous system, underscoring the critical requirement for genome stability in this tissue. A striking example of this is defective enzymatic activity of polynucleotide kinase-phosphatase (PNKP), leading to microcephaly or neurodegeneration. Notably, the broad neural impact of mutations in PNKP can result in markedly different disease entities, even when the inherited mutation is the same. For example microcephaly with seizures (MCSZ) results from various hypomorphic PNKP mutations, as does ataxia with oculomotor apraxia 4 (AOA4). Thus, other contributing factors influence the neural phenotype when PNKP is disabled. Here we consider the role for PNKP in maintaining brain function and how perturbation in its activity can account for the varied pathology of neurodegeneration or microcephaly present in MCSZ and AOA4 respectively.
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Affiliation(s)
- Lavinia C Dumitrache
- Dept. of Genetics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Peter J McKinnon
- Dept. of Genetics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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131
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Armon C. Accrued somatic mutations (nucleic acid changes) trigger ALS: 2005-2015 update. Muscle Nerve 2016; 53:842-9. [PMID: 26799358 DOI: 10.1002/mus.25049] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2016] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a multilevel disease of the motor neuron system. The mechanisms triggering disease onset should be considered separately from those facilitating its spread and motor neuron death. In 2005, I brought together clinical and epidemiological evidence to support the hypothesis that acquired nucleic acid changes may trigger sporadic ALS. Since 2005, the conceptual foundations for this hypothesis have been strengthened. The journal Amyotrophic Lateral Sclerosis was renamed Amyotrophic Lateral Sclerosis & Frontotemporal Degeneration. The focal onset, with simultaneous initial maximal upper and lower motor neuron involvement in the region of onset, and patterns of spread, were characterized further. Clues from the epidemiology of sporadic ALS were affirmed by quantitative analysis, including the increase in disease incidence with age, suggesting accrual of time-dependent changes, and the confirmation of smoking as an established risk factor. Additional observations support the conclusion that accrued somatic mutations trigger onset of ALS. Muscle Nerve 53: 842-849, 2016.
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Affiliation(s)
- Carmel Armon
- Tel Aviv University Sackler Faculty of Medicine and Assaf Harofeh Medical Center, Israel
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132
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Shang Y, Huang EJ. Mechanisms of FUS mutations in familial amyotrophic lateral sclerosis. Brain Res 2016; 1647:65-78. [PMID: 27033831 DOI: 10.1016/j.brainres.2016.03.036] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 03/22/2016] [Accepted: 03/24/2016] [Indexed: 12/13/2022]
Abstract
Recent advances in the genetics of amyotrophic lateral sclerosis (ALS) have provided key mechanistic insights to the pathogenesis of this devastating neurodegenerative disease. Among many etiologies for ALS, the identification of mutations and proteinopathies in two RNA binding proteins, TDP-43 (TARDBP or TAR DNA binding protein 43) and its closely related RNA/DNA binding protein FUS (fused in sarcoma), raises the intriguing possibility that perturbations to the RNA homeostasis and metabolism in neurons may contribute to the pathogenesis of these diseases. Although the similarities between TDP-43 and FUS suggest that mutations and proteinopathy involving these two proteins may converge on the same mechanisms leading to neurodegeneration, there is increasing evidence that FUS mutations target distinct mechanisms to cause early disease onset and aggressive progression of disease. This review focuses on the recent advances on the molecular, cellular and genetic approaches to uncover the mechanisms of wild type and mutant FUS proteins during development and in neurodegeneration. These findings provide important insights to understand how FUS mutations may perturb the maintenance of dendrites through fundamental processes in RNA splicing, RNA transport and DNA damage response/repair. These results contribute to the understanding of phenotypic manifestations in neurodegeneration related to FUS mutations, and to identify important directions for future investigations. This article is part of a Special Issue entitled SI:RNA Metabolism in Disease.
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Affiliation(s)
- Yulei Shang
- Department of Pathology, University of California San Francisco, San Francisco, CA, United States
| | - Eric J Huang
- Department of Pathology, University of California San Francisco, San Francisco, CA, United States; Pathology Service 113B, VA Medical Center, San Francisco, CA, United States.
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133
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Castillo DS, Campalans A, Belluscio LM, Carcagno AL, Radicella JP, Cánepa ET, Pregi N. E2F1 and E2F2 induction in response to DNA damage preserves genomic stability in neuronal cells. Cell Cycle 2016; 14:1300-14. [PMID: 25892555 DOI: 10.4161/15384101.2014.985031] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
E2F transcription factors regulate a wide range of biological processes, including the cellular response to DNA damage. In the present study, we examined whether E2F family members are transcriptionally induced following treatment with several genotoxic agents, and have a role on the cell DNA damage response. We show a novel mechanism, conserved among diverse species, in which E2F1 and E2F2, the latter specifically in neuronal cells, are transcriptionally induced after DNA damage. This upregulation leads to increased E2F1 and E2F2 protein levels as a consequence of de novo protein synthesis. Ectopic expression of these E2Fs in neuronal cells reduces the level of DNA damage following genotoxic treatment, while ablation of E2F1 and E2F2 leads to the accumulation of DNA lesions and increased apoptotic response. Cell viability and DNA repair capability in response to DNA damage induction are also reduced by the E2F1 and E2F2 deficiencies. Finally, E2F1 and E2F2 accumulate at sites of oxidative and UV-induced DNA damage, and interact with γH2AX DNA repair factor. As previously reported for E2F1, E2F2 promotes Rad51 foci formation, interacts with GCN5 acetyltransferase and induces histone acetylation following genotoxic insult. The results presented here unveil a new mechanism involving E2F1 and E2F2 in the maintenance of genomic stability in response to DNA damage in neuronal cells.
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Affiliation(s)
- Daniela S Castillo
- a Laboratorio de Biología Molecular; Departamento de Química Biológica; Facultad de Ciencias Exactas y Naturales ; Universidad de Buenos Aires ; Ciudad de Buenos Aires , Argentina
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134
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Dong ZZ, Zhang L, Qiao M, Ge J, Liu AL, Li ZH. A label-free assay for T4 polynucleotide kinase/phosphatase activity and its inhibitors based on poly(thymine)-templated copper nanoparticles. Talanta 2016; 146:253-8. [DOI: 10.1016/j.talanta.2015.08.055] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 08/17/2015] [Accepted: 08/24/2015] [Indexed: 01/01/2023]
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135
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Liu IH, Ford JM, Kunz PL. DNA-repair defects in pancreatic neuroendocrine tumors and potential clinical applications. Cancer Treat Rev 2015; 44:1-9. [PMID: 26924193 DOI: 10.1016/j.ctrv.2015.11.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 01/09/2023]
Abstract
BACKGROUND The role of DNA repair in pathogenesis and response to treatment is not well understood in pancreatic neuroendocrine tumors (pNETs). However, the existing literature reveals important preliminary trends and targets in the genetic landscape of pNETs. Notably, pNETs have been shown to harbor defects in the direct reversal MGMT gene and the DNA mismatch repair genes, suggesting that these genes may be strong candidates for further prospective studies. METHODS PubMed searches were conducted for original studies assessing the DNA repair genes MGMT and MMR in pNETs, as well as for PTEN and MEN1, which are not directly DNA repair genes but are involved in DNA repair pathways. Searches were specific to pNETs, yielding five original studies on MGMT and four on MMR. Six original papers studied PTEN in pNETs. Five studied MEN1 in pNETs, and two others implicated MEN1 in DNA repair processes. RESULTS The five studies on MGMT in pNET tumor samples found MGMT loss of between 24% and 51% of tumor samples by IHC staining and between 0% and 40% by promoter hypermethylation, revealing discrepancies in methods assessing MGMT expression as well as potential weaknesses in the correlation between MGMT IHC expression and promoter hypermethylation rates. Four studies on MMR in pNET tumor samples indicated similar ambiguities, as promoter hypermethylation of the MLH1 MMR gene ranged from 0% to 31% of pNETs, while IHC staining revealed loss of MMR genes in between 0% and 36% of pNETs sampled. Studies also indicated that PTEN and MEN1 are commonly mutated or underexpressed genes in pNETs, although frequency of mutation or loss of expression was again variable among different studies. CONCLUSION Further studies are essential in determining a more thorough repertoire of DNA repair defects in pNETs and the clinical significance of these defects. This literature review synthesises the existing knowledge of relevant DNA repair pathways and studies of the specific genes that carry out these repair mechanisms in pNETs.
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Affiliation(s)
| | - James M Ford
- Stanford University School of Medicine, United States
| | - Pamela L Kunz
- Stanford University School of Medicine, 875 Blake Wilbur Drive, Stanford, CA 94305-5826, United States.
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136
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Linking, thinking & fixing: the story about the 2015 Chemistry Nobel Prize and the future of science. Sci Bull (Beijing) 2015. [DOI: 10.1007/s11434-015-0932-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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137
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Abstract
DNA damage is correlated with and may drive the ageing process. Neurons in the brain are postmitotic and are excluded from many forms of DNA repair; therefore, neurons are vulnerable to various neurodegenerative diseases. The challenges facing the field are to understand how and when neuronal DNA damage accumulates, how this loss of genomic integrity might serve as a 'time keeper' of nerve cell ageing and why this process manifests itself as different diseases in different individuals.
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Affiliation(s)
- Hei-man Chow
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.,Institute for Advanced Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Karl Herrup
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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138
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Maynard S, Fang EF, Scheibye-Knudsen M, Croteau DL, Bohr VA. DNA Damage, DNA Repair, Aging, and Neurodegeneration. Cold Spring Harb Perspect Med 2015; 5:cshperspect.a025130. [PMID: 26385091 DOI: 10.1101/cshperspect.a025130] [Citation(s) in RCA: 242] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Aging in mammals is accompanied by a progressive atrophy of tissues and organs, and stochastic damage accumulation to the macromolecules DNA, RNA, proteins, and lipids. The sequence of the human genome represents our genetic blueprint, and accumulating evidence suggests that loss of genomic maintenance may causally contribute to aging. Distinct evidence for a role of imperfect DNA repair in aging is that several premature aging syndromes have underlying genetic DNA repair defects. Accumulation of DNA damage may be particularly prevalent in the central nervous system owing to the low DNA repair capacity in postmitotic brain tissue. It is generally believed that the cumulative effects of the deleterious changes that occur in aging, mostly after the reproductive phase, contribute to species-specific rates of aging. In addition to nuclear DNA damage contributions to aging, there is also abundant evidence for a causative link between mitochondrial DNA damage and the major phenotypes associated with aging. Understanding the mechanistic basis for the association of DNA damage and DNA repair with aging and age-related diseases, such as neurodegeneration, would give insight into contravening age-related diseases and promoting a healthy life span.
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Affiliation(s)
- Scott Maynard
- Department of Cellular and Molecular Medicine, Center for Healthy Aging, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Evandro Fei Fang
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224
| | - Morten Scheibye-Knudsen
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224
| | - Vilhelm A Bohr
- Department of Cellular and Molecular Medicine, Center for Healthy Aging, University of Copenhagen, DK-2200 Copenhagen, Denmark Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224
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139
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Abstract
DNA damage is caused by either endogenous cellular metabolic processes such as hydrolysis, oxidation, alkylation, and DNA base mismatches, or exogenous sources including ultraviolet (UV) light, ionizing radiation, and chemical agents. Damaged DNA that is not properly repaired can lead to genomic instability, driving tumorigenesis. To protect genomic stability, mammalian cells have evolved highly conserved DNA repair mechanisms to remove and repair DNA lesions. Telomeres are composed of long tandem TTAGGG repeats located at the ends of chromosomes. Maintenance of functional telomeres is critical for preventing genome instability. The telomeric sequence possesses unique features that predispose telomeres to a variety of DNA damage induced by environmental genotoxins. This review briefly describes the relevance of excision repair pathways in telomere maintenance, with the focus on base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). By summarizing current knowledge on excision repair of telomere damage and outlining many unanswered questions, it is our hope to stimulate further interest in a better understanding of excision repair processes at telomeres and in how these processes contribute to telomere maintenance.
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Affiliation(s)
- Pingping Jia
- Elson S. Floyd College of Medicine, United States
| | - Chengtao Her
- School of Molecular Biosciences, Washington State University, United States
| | - Weihang Chai
- Elson S. Floyd College of Medicine, United States; School of Molecular Biosciences, Washington State University, United States.
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140
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Evison BJ, Sleebs BE, Watson KG, Phillips DR, Cutts SM. Mitoxantrone, More than Just Another Topoisomerase II Poison. Med Res Rev 2015; 36:248-99. [PMID: 26286294 DOI: 10.1002/med.21364] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 07/13/2015] [Accepted: 07/14/2015] [Indexed: 02/06/2023]
Abstract
Mitoxantrone is a synthetic anthracenedione originally developed to improve the therapeutic profile of the anthracyclines and is commonly applied in the treatment of breast and prostate cancers, lymphomas, and leukemias. A comprehensive overview of the drug's molecular, biochemical, and cellular pharmacology is presented here, beginning with the cardiotoxic nature of its predecessor doxorubicin and how these properties shaped the pharmacology of mitoxantrone itself. Although mitoxantrone is firmly established as a DNA topoisomerase II poison within mammalian cells, it is now clear that the drug interacts with a much broader range of biological macromolecules both covalently and noncovalently. Here, we consider each of these interactions in the context of their wider biological relevance to cancer therapy and highlight how they may be exploited to further enhance the therapeutic value of mitoxantrone. In doing so, it is now clear that mitoxantrone is more than just another topoisomerase II poison.
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Affiliation(s)
- Benny J Evison
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Victoria, 3086, Australia
| | - Brad E Sleebs
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Keith G Watson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Don R Phillips
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Victoria, 3086, Australia
| | - Suzanne M Cutts
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Victoria, 3086, Australia
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141
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Shimada M, Dumitrache LC, Russell HR, McKinnon PJ. Polynucleotide kinase-phosphatase enables neurogenesis via multiple DNA repair pathways to maintain genome stability. EMBO J 2015; 34:2465-80. [PMID: 26290337 DOI: 10.15252/embj.201591363] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 07/09/2015] [Indexed: 11/09/2022] Open
Abstract
Polynucleotide kinase-phosphatase (PNKP) is a DNA repair factor possessing both 5'-kinase and 3'-phosphatase activities to modify ends of a DNA break prior to ligation. Recently, decreased PNKP levels were identified as the cause of severe neuropathology present in the human microcephaly with seizures (MCSZ) syndrome. Utilizing novel murine Pnkp alleles that attenuate expression and a T424GfsX48 frame-shift allele identified in MCSZ individuals, we determined how PNKP inactivation impacts neurogenesis. Mice with PNKP inactivation in neural progenitors manifest neurodevelopmental abnormalities and postnatal death. This severe phenotype involved defective base excision repair and non-homologous end-joining, pathways required for repair of both DNA single- and double-strand breaks. Although mice homozygous for the T424GfsX48 allele were lethal embryonically, attenuated PNKP levels (akin to MCSZ) showed general neurodevelopmental defects, including microcephaly, indicating a critical developmental PNKP threshold. Directed postnatal neural inactivation of PNKP affected specific subpopulations including oligodendrocytes, indicating a broad requirement for genome maintenance, both during and after neurogenesis. These data illuminate the basis for selective neural vulnerability in DNA repair deficiency disease.
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Affiliation(s)
- Mikio Shimada
- Department of Genetics, St Jude Children's Research Hospital, Memphis, TN, USA
| | | | - Helen R Russell
- Department of Genetics, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Peter J McKinnon
- Department of Genetics, St Jude Children's Research Hospital, Memphis, TN, USA
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142
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Romero AM, Palanca A, Ruiz-Soto M, Llorca J, Marín MP, Renau-Piqueras J, Berciano MT, Lafarga M. Chronic Alcohol Exposure Decreases 53BP1 Protein Levels Leading to a Defective DNA Repair in Cultured Primary Cortical Neurons. Neurotox Res 2015; 29:69-79. [PMID: 26264240 DOI: 10.1007/s12640-015-9554-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 07/08/2015] [Accepted: 08/04/2015] [Indexed: 12/24/2022]
Abstract
Chronic alcohol consumption may cause neurodevelopmental and neurodegenerative disorders. Alcohol neurotoxicity is associated with the production of acetaldehyde and reactive oxygen species that induce oxidative DNA damage. However, the molecular mechanisms by which ethanol disturbs the DNA damage response (DDR), resulting in a defective DNA repair, remain unknown. Here, we have used cultured primary cortical neurons exposed to 50 or 100 mM ethanol for 7 days to analyze the ethanol-induced DDR. Ethanol exposure produced a dose-dependent generation of double strand breaks and the formation of DNA damage foci immunoreactive for the histone γH2AX, a DNA damage marker, and for the ubiquitylated H2A, which is involved in chromatin remodeling at DNA damage sites. Importantly, these DNA damage foci failed to recruit the protein 53BP1, a crucial DNA repair factor. This effect was associated with a drop in 53BP1 mRNA and protein levels and with an inhibition of global transcription. Moreover, ethanol-exposed neurons treated with ionizing radiation (2 Gy) also failed to recruit 53BP1 at DNA damage foci and exhibited a greater vulnerability to DNA lesions than irradiated control neurons. Our results support that defective DNA repair, mediated by the deficient expression and recruitment of 53BP1 to DNA damage sites, represents a novel mechanism involved in ethanol neurotoxicity. The design of therapeutic strategies that increase or stabilize 53BP1 levels might potentially promote DNA repair and partially compensate alcohol neurotoxicity.
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Affiliation(s)
- Ana M Romero
- Sección de Biología y Patología Celular, Centro de Investigación, Hospital La Fe, Valencia, Spain.,Unidad de Microscopía IIS La Fe, Valencia, Spain
| | - Ana Palanca
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Av. Cardenal Herrera Oria s/n, 39011, Santander, Spain
| | - Maria Ruiz-Soto
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Av. Cardenal Herrera Oria s/n, 39011, Santander, Spain
| | - Javier Llorca
- Division of Epidemiology and Public Health, "CIBER de Epidemiología y Salud Pública (CIBERESP)", IDIVAL, University of Cantabria, Santander, Spain
| | | | - Jaime Renau-Piqueras
- Sección de Biología y Patología Celular, Centro de Investigación, Hospital La Fe, Valencia, Spain
| | - Maria T Berciano
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Av. Cardenal Herrera Oria s/n, 39011, Santander, Spain
| | - Miguel Lafarga
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Av. Cardenal Herrera Oria s/n, 39011, Santander, Spain.
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143
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Bujdoso R, Landgraf M, Jackson WS, Thackray AM. Prion-induced neurotoxicity: Possible role for cell cycle activity and DNA damage response. World J Virol 2015; 4:188-197. [PMID: 26279981 PMCID: PMC4534811 DOI: 10.5501/wjv.v4.i3.188] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 03/19/2015] [Accepted: 04/30/2015] [Indexed: 02/05/2023] Open
Abstract
Protein misfolding neurodegenerative diseases arise through neurotoxicity induced by aggregation of host proteins. These conditions include Alzheimer’s disease, Huntington’s disease, Parkinson’s disease, motor neuron disease, tauopathies and prion diseases. Collectively, these conditions are a challenge to society because of the increasing aged population and through the real threat to human food security by animal prion diseases. It is therefore important to understand the cellular and molecular mechanisms that underlie protein misfolding-induced neurotoxicity as this will form the basis for designing strategies to alleviate their burden. Prion diseases are an important paradigm for neurodegenerative conditions in general since several of these maladies have now been shown to display prion-like phenomena. Increasingly, cell cycle activity and the DNA damage response are recognised as cellular events that participate in the neurotoxic process of various neurodegenerative diseases, and their associated animal models, which suggests they are truly involved in the pathogenic process and are not merely epiphenomena. Here we review the role of cell cycle activity and the DNA damage response in neurodegeneration associated with protein misfolding diseases, and suggest that these events contribute towards prion-induced neurotoxicity. In doing so, we highlight PrP transgenic Drosophila as a tractable model for the genetic analysis of transmissible mammalian prion disease.
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144
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Evans AR, Gu L, Guerrero R, Robinson RAS. Global cPILOT analysis of the APP/PS-1 mouse liver proteome. Proteomics Clin Appl 2015; 9:872-84. [PMID: 25620666 DOI: 10.1002/prca.201400149] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 11/20/2014] [Accepted: 01/21/2015] [Indexed: 12/19/2022]
Abstract
PURPOSE A quantitative proteomics strategy called combined precursor isotopic labeling and isobaric tagging (cPILOT) was designed to discover alterations in the amyloid precursor protein/presenilin-1 (APP/PS-1) mouse liver proteome. The multiplexing strategy allows simultaneous quantitation of 12 samples in a single experiment. EXPERIMENTAL DESIGN For cPILOT samples, six APP/PS-1 and six heterozygous mouse livers were modified using precursor dimethylation (pH 2.5) followed by isobaric tagging (pH 8.0). Samples were pooled, fractioned with strong cation exchange, and analyzed using RPLC-MS(3) for protein identification and relative quantitation. In order to increase proteome coverage, a two-tiered data collection strategy was employed. Six duplex precursor dimethylation experiments were also performed to verify cPILOT protein quantitation. RESULTS The combination of cPILOT with precursor dimethylation data resulted in 2437 total liver proteins identified and 77 differentially expressed proteins in APP/PS-1 liver. Differentially expressed proteins are involved in metabolic processes such as B-oxidation, pyruvate metabolism, and glucose regulation. CONCLUSIONS AND CLINICAL RELEVANCE cPILOT expands protein quantitation using isobaric tags and can be applied to any clinical laboratory interested in enhanced multiplexing strategies. Differentially expressed proteins in APP/PS-1 mouse liver suggest the potential use of ketone bodies to alleviate metabolic dysregulation in Alzheimer's disease brain. Our work also suggests alterations in the alanine cycle potentially leading to hyperammonia production, may contribute to Alzheimer's disease pathogenesis.
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Affiliation(s)
- Adam R Evans
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Liqing Gu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rodolfo Guerrero
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Renã A S Robinson
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA
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145
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Quintens R, Verreet T, Janssen A, Neefs M, Leysen L, Michaux A, Verslegers M, Samari N, Pani G, Verheyde J, Baatout S, Benotmane MA. Identification of novel radiation-induced p53-dependent transcripts extensively regulated during mouse brain development. Biol Open 2015; 4:331-44. [PMID: 25681390 PMCID: PMC4359739 DOI: 10.1242/bio.20149969] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ionizing radiation is a potent activator of the tumor suppressor gene p53, which itself regulates the transcription of genes involved in canonical pathways such as the cell cycle, DNA repair and apoptosis as well as other biological processes like metabolism, autophagy, differentiation and development. In this study, we performed a meta-analysis on gene expression data from different in vivo and in vitro experiments to identify a signature of early radiation-responsive genes which were predicted to be predominantly regulated by p53. Moreover, we found that several genes expressed different transcript isoforms after irradiation in a p53-dependent manner. Among this gene signature, we identified novel p53 targets, some of which have not yet been functionally characterized. Surprisingly, in contrast to genes from the canonical p53-regulated pathways, our gene signature was found to be highly enriched during embryonic and post-natal brain development and during in vitro neuronal differentiation. Furthermore, we could show that for a number of genes, radiation-responsive transcript variants were upregulated during development and differentiation, while radiation non-responsive variants were not. This suggests that radiation exposure of the developing brain and immature cortical neurons results in the p53-mediated activation of a neuronal differentiation program. Overall, our results further increase the knowledge of the radiation-induced p53 network of the embryonic brain and provide more evidence concerning the importance of p53 and its transcriptional targets during mouse brain development.
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Affiliation(s)
- Roel Quintens
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium
| | - Tine Verreet
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium Laboratory of Neural Circuit Development and Regeneration, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, B-3000 Leuven, Belgium
| | - Ann Janssen
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium
| | - Mieke Neefs
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium
| | - Liselotte Leysen
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium
| | - Arlette Michaux
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium
| | - Mieke Verslegers
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium
| | - Nada Samari
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium
| | - Giuseppe Pani
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium Present address: Nutritional Biochemistry and Space Biology Lab, Department of Pharmacology and Bio-molecular Sciences, Università degli Studi di Milano, 20122 Milano, Italy
| | - Joris Verheyde
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium
| | - Sarah Baatout
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium Cell Systems and Imaging Research Group (CSI), Department of Molecular Biotechnology, Ghent University, B-9000 Ghent, Belgium
| | - Mohammed A Benotmane
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, B-2400 Mol, Belgium
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146
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Arjunan KP, Sharma VK, Ptasinska S. Effects of atmospheric pressure plasmas on isolated and cellular DNA-a review. Int J Mol Sci 2015; 16:2971-3016. [PMID: 25642755 PMCID: PMC4346876 DOI: 10.3390/ijms16022971] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/14/2015] [Accepted: 01/15/2015] [Indexed: 01/02/2023] Open
Abstract
Atmospheric Pressure Plasma (APP) is being used widely in a variety of biomedical applications. Extensive research in the field of plasma medicine has shown the induction of DNA damage by APP in a dose-dependent manner in both prokaryotic and eukaryotic systems. Recent evidence suggests that APP-induced DNA damage shows potential benefits in many applications, such as sterilization and cancer therapy. However, in several other applications, such as wound healing and dentistry, DNA damage can be detrimental. This review reports on the extensive investigations devoted to APP interactions with DNA, with an emphasis on the critical role of reactive species in plasma-induced damage to DNA. The review consists of three main sections dedicated to fundamental knowledge of the interactions of reactive oxygen species (ROS)/reactive nitrogen species (RNS) with DNA and its components, as well as the effects of APP on isolated and cellular DNA in prokaryotes and eukaryotes.
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Affiliation(s)
| | - Virender K Sharma
- Department of Environmental and Occupational Health, School of Public Health, Texas A&M University, 1266 TAMU, College Station, TX 77843, USA.
| | - Sylwia Ptasinska
- Radiation Laboratory, University of Notre Dame, Notre Dame, IN 46556, USA.
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147
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Dixon M, Woodrick J, Gupta S, Karmahapatra SK, Devito S, Vasudevan S, Dakshanamurthy S, Adhikari S, Yenugonda VM, Roy R. Naturally occurring polyphenol, morin hydrate, inhibits enzymatic activity of N-methylpurine DNA glycosylase, a DNA repair enzyme with various roles in human disease. Bioorg Med Chem 2015; 23:1102-11. [PMID: 25650313 DOI: 10.1016/j.bmc.2014.12.067] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/19/2014] [Accepted: 12/28/2014] [Indexed: 10/24/2022]
Abstract
Interest in the mechanisms of DNA repair pathways, including the base excision repair (BER) pathway specifically, has heightened since these pathways have been shown to modulate important aspects of human disease. Modulation of the expression or activity of a particular BER enzyme, N-methylpurine DNA glycosylase (MPG), has been demonstrated to play a role in carcinogenesis and resistance to chemotherapy as well as neurodegenerative diseases, which has intensified the focus on studying MPG-related mechanisms of repair. A specific small molecule inhibitor for MPG activity would be a valuable biochemical tool for understanding these repair mechanisms. By screening several small molecule chemical libraries, we identified a natural polyphenolic compound, morin hydrate, which inhibits MPG activity specifically (IC50=2.6μM). Detailed mechanism analysis showed that morin hydrate inhibited substrate DNA binding of MPG, and eventually the enzymatic activity of MPG. Computational docking studies with an x-ray derived MPG structure as well as comparison studies with other structurally-related flavonoids offer a rationale for the inhibitory activity of morin hydrate observed. The results of this study suggest that the morin hydrate could be an effective tool for studying MPG function and it is possible that morin hydrate and its derivatives could be utilized in future studies focused on the role of MPG in human disease.
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Affiliation(s)
- Monica Dixon
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, United States
| | - Jordan Woodrick
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, United States
| | - Suhani Gupta
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, United States
| | - Soumendra Krishna Karmahapatra
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, United States
| | - Stephen Devito
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, United States
| | - Sona Vasudevan
- Department of Biochemistry, Georgetown University Medical School, Washington, DC 20057, United States
| | - Sivanesan Dakshanamurthy
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, United States
| | - Sanjay Adhikari
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, United States
| | - Venkata M Yenugonda
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, United States
| | - Rabindra Roy
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, United States.
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148
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Nhej1 Deficiency Causes Abnormal Development of the Cerebral Cortex. Mol Neurobiol 2014; 52:771-82. [PMID: 25288157 DOI: 10.1007/s12035-014-8919-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 09/29/2014] [Indexed: 12/12/2022]
Abstract
DNA double-strand breaks (DSBs) frequently occur in rapidly dividing cells such as proliferating progenitors during central nervous system development. If they cannot be repaired, these lesions will cause cell death. The non-homologous end joining (NHEJ) DNA repair pathway is the only pathway available to repair DSBs in post-mitotic neurons. The non-homologous end joining factor 1 (Nhej1) protein is a key component of the NHEJ pathway. Nhej1 interacts with Xrcc4 and Lig4 to repair DSBs. Loss of function of Xrcc4 or Lig4 is embryonic lethal in the mouse while the loss of Nhej1 is not. Surprisingly, the brains of Nhej1-deficient mice appear to be normal although NHEJ1 deficiency in humans causes severe neurological dysfunction and microcephaly. Here, we studied the consequences of Nhej1 dysfunction for the development of the cerebral cortex using in utero electroporation of inactivating small hairpin RNAs (shRNAs) in the developing rat brain. We found that decreasing Nhej1 expression during neuronal migration phases causes severe neuronal migration defects visualized at embryonic stages by an accumulation of heterotopic neurons in the intermediate zone. Knocked-down cells die by 7 days after birth and the brain regions where RNA interference was achieved are structurally abnormal, suffering from a reduction of the width of the external cortical layers. These results indicate that the Nhej1 protein is necessary for proper rat cortical development. Neurons unable to properly repair DNA DSBs are unable to reach their final destination during the development and undergo apoptosis, leading to an abnormal cortical development.
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149
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Houlihan SL, Feng Y. The scaffold protein Nde1 safeguards the brain genome during S phase of early neural progenitor differentiation. eLife 2014; 3:e03297. [PMID: 25245017 PMCID: PMC4170211 DOI: 10.7554/elife.03297] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 09/01/2014] [Indexed: 12/14/2022] Open
Abstract
Successfully completing the S phase of each cell cycle ensures genome integrity. Impediment of DNA replication can lead to DNA damage and genomic disorders. In this study, we show a novel function for NDE1, whose mutations cause brain developmental disorders, in safeguarding the genome through S phase during early steps of neural progenitor fate restrictive differentiation. Nde1 mutant neural progenitors showed catastrophic DNA double strand breaks concurrent with the DNA replication. This evoked DNA damage responses, led to the activation of p53-dependent apoptosis, and resulted in the reduction of neurons in cortical layer II/III. We discovered a nuclear pool of Nde1, identified the interaction of Nde1 with cohesin and its associated chromatin remodeler, and showed that stalled DNA replication in Nde1 mutants specifically occurred in mid-late S phase at heterochromatin domains. These findings suggest that NDE1-mediated heterochromatin replication is indispensible for neuronal differentiation, and that the loss of NDE1 function may lead to genomic neurological disorders.
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Affiliation(s)
- Shauna L Houlihan
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States
- Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, United States
- Driskill Graduate Program, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Yuanyi Feng
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States
- Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, United States
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150
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Skourti-Stathaki K, Proudfoot NJ. A double-edged sword: R loops as threats to genome integrity and powerful regulators of gene expression. Genes Dev 2014; 28:1384-96. [PMID: 24990962 PMCID: PMC4083084 DOI: 10.1101/gad.242990.114] [Citation(s) in RCA: 391] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
R loops are three-stranded nucleic acid structures that comprise nascent RNA hybridized with the DNA template, leaving the nontemplate DNA single-stranded. These structures form naturally during transcription even though their persistent formation can have deleterious effects on genome integrity. Interestingly, an increasing number of studies also suggest that R loops function as potential gene expression regulators. Here, Skourti-Stathaki and Proudfoot review the most recent findings about R loops, highlighting their opposite roles in cellular fitness. R loops are three-stranded nucleic acid structures that comprise nascent RNA hybridized with the DNA template, leaving the nontemplate DNA single-stranded. R loops form naturally during transcription even though their persistent formation can be a risky outcome with deleterious effects on genome integrity. On the other hand, over the last few years, an increasingly strong case has been built for R loops as potential regulators of gene expression. Therefore, understanding their function and regulation under these opposite situations is essential to fully characterize the mechanisms that control genome integrity and gene expression. Here we review recent findings about these interesting structures that highlight their opposite roles in cellular fitness.
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Affiliation(s)
| | - Nicholas J Proudfoot
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
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