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Imarisio A, Pilotto A, Lupini A, Biasiotto G, Zanella I, Currò R, Vegezzi E, Cortese A, Palmieri I, Valente EM, Padovani A. Heterozygous APTX mutation associated with atypical multiple system atrophy-like phenotype: A case report. Parkinsonism Relat Disord 2024; 123:106943. [PMID: 38555792 DOI: 10.1016/j.parkreldis.2024.106943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/19/2024] [Accepted: 03/19/2024] [Indexed: 04/02/2024]
Abstract
We describe here a 73-year-old patient presenting with atypical MSA-P-like phenotype carrying a monoallelic p. W279X mutation in the APTX gene, which causes ataxia with oculomotor apraxia type 1 (AOA1) when in homozygous state. We hypothesize that rare monoallelic APTX variants could modulate MSA risk and phenotype.
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Affiliation(s)
- Alberto Imarisio
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; IRCCS Mondino Foundation, Pavia, Italy.
| | - Andrea Pilotto
- Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy; Neurology Unit, Department of Continuity of Care and Frailty, ASST Spedali Civili Brescia University Hospital, Italy; Laboratory of Digital Neurology and Biosensors, University of Brescia, Italy
| | - Alessandro Lupini
- Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy; Neurology Unit, Department of Continuity of Care and Frailty, ASST Spedali Civili Brescia University Hospital, Italy
| | - Giorgio Biasiotto
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy; Highly Specialized Laboratory, ASST Spedali Civili di Brescia, Brescia, Italy
| | - Isabella Zanella
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy; Cytogenetics and Molecular Genetics Laboratory, Diagnostic Department, ASST Spedali Civili di Brescia, Brescia, Italy
| | - Riccardo Currò
- Department of Neuromuscular Disease, UCL Queen Square Institute of Neurology, London, UK; Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
| | - Elisa Vegezzi
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy; IRCCS Mondino Foundation, Pavia, Italy
| | - Andrea Cortese
- Department of Neuromuscular Disease, UCL Queen Square Institute of Neurology, London, UK; Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
| | - Ilaria Palmieri
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; IRCCS Mondino Foundation, Pavia, Italy
| | - Enza Maria Valente
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; IRCCS Mondino Foundation, Pavia, Italy
| | - Alessandro Padovani
- Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy; Neurology Unit, Department of Continuity of Care and Frailty, ASST Spedali Civili Brescia University Hospital, Italy; Laboratory of Digital Neurology and Biosensors, University of Brescia, Italy
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Van de Vondel L, De Winter J, Timmerman V, Baets J. Overarching pathomechanisms in inherited peripheral neuropathies, spastic paraplegias, and cerebellar ataxias. Trends Neurosci 2024; 47:227-238. [PMID: 38360512 DOI: 10.1016/j.tins.2024.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 01/23/2024] [Accepted: 01/24/2024] [Indexed: 02/17/2024]
Abstract
International consortia collaborating on the genetics of rare diseases have significantly boosted our understanding of inherited neurological disorders. Historical clinical classification boundaries were drawn between disorders with seemingly different etiologies, such as inherited peripheral neuropathies (IPNs), spastic paraplegias, and cerebellar ataxias. These clinically defined borders are being challenged by the identification of mutations in genes displaying wide phenotypic spectra and by shared pathomechanistic themes, which are valuable indications for therapy development. We highlight common cellular alterations that underlie this genetic landscape, including alteration of cytoskeleton, axonal transport, mitochondrial function, and DNA repair response. Finally, we discuss venues for future research using the long axonopathies of the PNS as a model to explore other neurogenetic disorders.
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Affiliation(s)
- Liedewei Van de Vondel
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
| | - Jonathan De Winter
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium; Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerp, Belgium
| | - Vincent Timmerman
- Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium; Peripheral Neuropathy Research Group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Jonathan Baets
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium; Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerp, Belgium.
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3
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Imamura R, Saito M, Shimada M, Kobayashi J, Ishiai M, Matsumoto Y. APTX acts in DNA double-strand break repair in a manner distinct from XRCC4. JOURNAL OF RADIATION RESEARCH 2023; 64:485-495. [PMID: 36940705 DOI: 10.1093/jrr/rrad007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 01/03/2023] [Indexed: 05/27/2023]
Abstract
Aprataxin (APTX), the product of the causative gene for hereditary neurogenerative syndromes Ataxia-oculomotor apraxia 1 and early onset ataxia with oculomotor apraxia and hypoalbuminemia, has an enzymatic activity of removing adenosine monophosphate from DNA 5'-end, which arises from abortive ligation by DNA ligases. It is also reported that APTX physically binds to XRCC1 and XRCC4, suggesting its involvement in DNA single-strand break repair (SSBR) and DNA double-strand break repair (DSBR) via non-homologous end joining pathway. Although the involvement of APTX in SSBR in association with XRCC1 has been established, the significance of APTX in DSBR and its interaction with XRCC4 have remained unclear. Here, we generated APTX knock-out (APTX-/-) cell from human osteosarcoma U2OS through CRISPR/Cas9-mediated genome editing system. APTX-/- cells exhibited increased sensitivity toward ionizing radiation (IR) and Camptothecin in association with retarded DSBR, as shown by increased number of retained γH2AX foci. However, the number of retained 53BP1 foci in APTX-/- cell was not discernibly different from wild-type cells, in stark contrast to XRCC4-depleted cells. The recruitment of GFP-tagged APTX (GFP-APTX) to the DNA damage sites was examined by laser micro-irradiation and live-cell imaging analysis using confocal microscope. The accumulation of GFP-APTX on the laser track was attenuated by siRNA-mediated depletion of XRCC1, but not XRCC4. Moreover, the deprivation of APTX and XRCC4 displayed additive inhibitory effects on DSBR after IR exposure and end joining of GFP reporter. These findings collectively suggest that APTX acts in DSBR in a manner distinct from XRCC4.
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Affiliation(s)
- Rikiya Imamura
- Laboratory for Zero-Carbon Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Mizuki Saito
- Laboratory for Zero-Carbon Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Mikio Shimada
- Laboratory for Zero-Carbon Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Junya Kobayashi
- Department of Radiological Sciences, School of Health Science at Narita, International University of Health and Welfare, 4-3 Kozunomori, Narita, Chiba 286-8686, Japan
| | - Masamichi Ishiai
- National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Yoshihisa Matsumoto
- Laboratory for Zero-Carbon Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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Species variations in XRCC1 recruitment strategies for FHA domain-containing proteins. DNA Repair (Amst) 2022; 110:103263. [PMID: 35026705 PMCID: PMC9282668 DOI: 10.1016/j.dnarep.2021.103263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/07/2021] [Accepted: 12/21/2021] [Indexed: 02/03/2023]
Abstract
DNA repair scaffolds XRCC1 and XRCC4 utilize a phosphopeptide FHA domain binding motif (FBM) of the form Y-x-x-pS-pT-D-E that supports recruitment of three identified FHA domain-containing DNA repair proteins: polynucleotide kinase/phosphatase (PNKP), aprataxin (APTX), and a third protein, APLF, that functions as a scaffold in support of non-homologous end joining (NHEJ). Mammalian dimeric XRCC4 is able to interact with two of these proteins at any given time, while monomeric XRCC1 binds only one. However, sequence analysis indicates that amphibian and teleost XRCC1 generally contain two FHA binding motifs. X1-FBM1, is similar to the single mammalian XRCC1 FBM and probably functions similarly. X1-FBM2, is more similar to mammalian XRCC4 FBM; it is located closer to the XRCC1 BRCT1 domain and probably is less discriminating among its three likely binding partners. Availability of an additional PNKP or APTX recruitment motif may alleviate the bottleneck that results from using a single FBM motif for recruitment of multiple repair factors. Alternatively, recruitment of APLF by X1-FBM2 may function to rescue a misdirected or unsuccessful SSB repair response by redirecting the damaged DNA to the NHEJ pathway, - a need that results from the ambiguity of the PARP1 signal regarding the nature of the damage. Evaluation of XRCC4 FBMs in acanthomorphs, which account for a majority of the reported teleost sequences, reveals the presence of an additional XRCC4-like paralog, distinct from other previously described members of the XRCC4 superfamily. The FBM is typically absent in acanthomorph XRCC4, but present in the XRCC4-like paralog. Modeling suggests that XRCC4 and its paralog may form homodimers or XRCC4-XRCC4-like heterodimers.
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Perez H, Abdallah MF, Chavira JI, Norris AS, Egeland MT, Vo KL, Buechsenschuetz CL, Sanghez V, Kim JL, Pind M, Nakamura K, Hicks GG, Gatti RA, Madrenas J, Iacovino M, McKinnon PJ, Mathews PJ. A novel, ataxic mouse model of ataxia telangiectasia caused by a clinically relevant nonsense mutation. eLife 2021; 10:64695. [PMID: 34723800 PMCID: PMC8601662 DOI: 10.7554/elife.64695] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 10/29/2021] [Indexed: 12/14/2022] Open
Abstract
Ataxia Telangiectasia (A-T) and Ataxia with Ocular Apraxia Type 1 (AOA1) are devastating neurological disorders caused by null mutations in the genome stability genes, A-T mutated (ATM) and Aprataxin (APTX), respectively. Our mechanistic understanding and therapeutic repertoire for treating these disorders are severely lacking, in large part due to the failure of prior animal models with similar null mutations to recapitulate the characteristic loss of motor coordination (i.e., ataxia) and associated cerebellar defects. By increasing genotoxic stress through the insertion of null mutations in both the Atm (nonsense) and Aptx (knockout) genes in the same animal, we have generated a novel mouse model that for the first time develops a progressively severe ataxic phenotype associated with atrophy of the cerebellar molecular layer. We find biophysical properties of cerebellar Purkinje neurons (PNs) are significantly perturbed (e.g., reduced membrane capacitance, lower action potential [AP] thresholds, etc.), while properties of synaptic inputs remain largely unchanged. These perturbations significantly alter PN neural activity, including a progressive reduction in spontaneous AP firing frequency that correlates with both cerebellar atrophy and ataxia over the animal’s first year of life. Double mutant mice also exhibit a high predisposition to developing cancer (thymomas) and immune abnormalities (impaired early thymocyte development and T-cell maturation), symptoms characteristic of A-T. Finally, by inserting a clinically relevant nonsense-type null mutation in Atm, we demonstrate that Small Molecule Read-Through (SMRT) compounds can restore ATM production, indicating their potential as a future A-T therapeutic.
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Affiliation(s)
- Harvey Perez
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States
| | - May F Abdallah
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States
| | - Jose I Chavira
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States
| | - Angelina S Norris
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States
| | - Martin T Egeland
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States
| | - Karen L Vo
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States
| | - Callan L Buechsenschuetz
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States
| | - Valentina Sanghez
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States
| | - Jeannie L Kim
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States
| | - Molly Pind
- Department of Biochemistry and Medical Genetics,Max Rady College of Medicine, University of Manitoba, Manitoba, Canada
| | - Kotoka Nakamura
- Department of Pathology & Laboratory Medicine, David Geffen School of Medicine, Los Angeles, United States
| | - Geoffrey G Hicks
- Department of Biochemistry and Medical Genetics,Max Rady College of Medicine, University of Manitoba, Manitoba, Canada
| | - Richard A Gatti
- Department of Pathology & Laboratory Medicine, David Geffen School of Medicine, Los Angeles, United States
| | - Joaquin Madrenas
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States.,Department of Medicine, Harbor-UCLA Medical Center, Torrance, United States
| | - Michelina Iacovino
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States.,Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, United States
| | - Peter J McKinnon
- Center for Pediatric Neurological Disease Research, St. Jude Pediatric Translational Neuroscience Initiative, St. Jude Children's Research Hospital, Memphis, United States
| | - Paul J Mathews
- The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, United States.,Department of Neurology, Harbor-UCLA Medical Center, Torrance, United States
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Immunological abnormalities in patients with early-onset ataxia with ocular motor apraxia and hypoalbuminemia. Clin Immunol 2021; 229:108776. [PMID: 34118401 DOI: 10.1016/j.clim.2021.108776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 05/12/2021] [Accepted: 06/06/2021] [Indexed: 11/21/2022]
Abstract
Early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH) is a neurodegenerative disorder caused by mutation in the aprataxin (APTX)-coding gene APTX, which is involved in DNA single-strand break repair (SSBR). The neurological abnormalities associated with EAOH are similar to those observed in patients with ataxia-telangiectasia. However, the immunological abnormalities in patients with EAOH have not been described. In this study, we report that EAOH patients have immunological abnormalities, including lymphopenia; decreased levels of CD4+ T-cells, CD8+ T-cells, and B-cells; hypogammaglobulinemia; low T-cell recombination excision circles and kappa-deleting element recombination circles; and oligoclonality of T-cell receptor β-chain variable repertoire. These immunological abnormalities vary among the EAOH patients. Additionally, mild radiosensitivity in the lymphocytes obtained from the patients with EAOH was demonstrated. These findings suggested that the immunological abnormalities and mild radiosensitivity evident in patients with EAOH could be probably caused by the DNA repair defects.
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DNA ligase I fidelity mediates the mutagenic ligation of pol β oxidized and mismatch nucleotide insertion products in base excision repair. J Biol Chem 2021; 296:100427. [PMID: 33600799 PMCID: PMC8024709 DOI: 10.1016/j.jbc.2021.100427] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 02/08/2021] [Accepted: 02/12/2021] [Indexed: 11/22/2022] Open
Abstract
DNA ligase I (LIG1) completes the base excision repair (BER) pathway at the last nick-sealing step after DNA polymerase (pol) β gap-filling DNA synthesis. However, the mechanism by which LIG1 fidelity mediates the faithful substrate-product channeling and ligation of repair intermediates at the final steps of the BER pathway remains unclear. We previously reported that pol β 8-oxo-2'-deoxyribonucleoside 5'-triphosphate insertion confounds LIG1, leading to the formation of ligation failure products with a 5'-adenylate block. Here, using reconstituted BER assays in vitro, we report the mutagenic ligation of pol β 8-oxo-2'-deoxyribonucleoside 5'-triphosphate insertion products and an inefficient ligation of pol β Watson-Crick-like dG:T mismatch insertion by the LIG1 mutant with a perturbed fidelity (E346A/E592A). Moreover, our results reveal that the substrate discrimination of LIG1 for the nicked repair intermediates with preinserted 3'-8-oxodG or mismatches is governed by mutations at both E346 and E592 residues. Finally, we found that aprataxin and flap endonuclease 1, as compensatory DNA-end processing enzymes, can remove the 5'-adenylate block from the abortive ligation products harboring 3'-8-oxodG or the 12 possible noncanonical base pairs. These findings contribute to the understanding of the role of LIG1 as an important determinant in faithful BER and how a multiprotein complex (LIG1, pol β, aprataxin, and flap endonuclease 1) can coordinate to prevent the formation of mutagenic repair intermediates with damaged or mismatched ends at the downstream steps of the BER pathway.
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Ababneh NA, Ali D, Al-Kurdi B, Sallam M, Alzibdeh AM, Salah B, Ryalat AT, Azab B, Sharrack B, Awidi A. Identification of APTX disease-causing mutation in two unrelated Jordanian families with cerebellar ataxia and sensitivity to DNA damaging agents. PLoS One 2020; 15:e0236808. [PMID: 32750061 PMCID: PMC7402469 DOI: 10.1371/journal.pone.0236808] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 07/13/2020] [Indexed: 11/26/2022] Open
Abstract
Background Ataxia with oculomotor apraxia type 1 (AOA1) is a rare autosomal recessive cerebellar ataxia, caused by mutations in the APTX gene. The disease is characterized by early-onset cerebellar ataxia, oculomotor apraxia and severe axonal polyneuropathy. The aim of this study was to detect the disease-causing variants in two unrelated consanguineous Jordanian families with cerebellar ataxia using whole exome sequencing (WES), and to correlate the identified mutation(s) with the clinical and cellular phenotypes. Methods WES was performed in three affected individuals and segregation analysis of p.W279* APTX candidate variant was performed. Expression levels of APTX were measured in patients’ skin fibroblasts and peripheral blood mononuclear cells, followed by western blot analysis in skin fibroblasts. Genotoxicity assay was performed to detect the sensitivity of APTX mutated cells to H2O2, MMC, MMS and etoposide. Results A recurrent homozygous nonsense variant in APTX gene (c.837G>A, p.W279*) was revealed in all affected individuals. qRT-PCR showed normal APTX levels in peripheral blood and lower levels in fibroblast cells. However, western blot showed the absence of APTX protein in patients’ skin fibroblasts. Significant hypersensitivity to H2O2, MMC and etoposide and lack of sensitivity to MMS were noted. Conclusions This is the first study to report the identification of a nonsense variant in the APTX gene (c.837G>A; p.W279*) in AOA1 patients within the Jordanian population. This study confirmed the need of WES to assist in the diagnosis of cerebellar ataxia and it emphasizes the importance of studying the pathophysiology of the APTX gene.
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Affiliation(s)
- Nidaa A. Ababneh
- Cell Therapy Center, The University of Jordan, Amman, Jordan
- * E-mail: , (NAA); (AA)
| | - Dema Ali
- Cell Therapy Center, The University of Jordan, Amman, Jordan
| | - Ban Al-Kurdi
- Cell Therapy Center, The University of Jordan, Amman, Jordan
| | - Malik Sallam
- Department of Pathology, Microbiology and Forensic Medicine, School of Medicine, The University of Jordan, Amman, Jordan
- Department of Clinical Laboratories and Forensic Medicine, Jordan University Hospital, Amman, Jordan
- Department of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | | | - Bareqa Salah
- General Surgery Department/Plastic & Reconstructive, Jordan University Hospital, The University of Jordan, Amman, Jordan
| | | | - Belal Azab
- Department of Pathology, Microbiology and Forensic Medicine, School of Medicine, The University of Jordan, Amman, Jordan
- Department of Human and Molecular Genetics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Basil Sharrack
- Academic Department of Neuroscience and Sheffield NIHR Neuroscience BRC, Royal Hallamshire Hospital and The University of Sheffield, Sheffield, United Kingdom
| | - Abdalla Awidi
- Cell Therapy Center, The University of Jordan, Amman, Jordan
- Hemostasis and Thrombosis Laboratory, School of Medicine, the University of Jordan, Amman, Jordan
- Department of Hematology and Oncology, Jordan University Hospital, Amman, Jordan
- * E-mail: , (NAA); (AA)
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Mei C, Lei L, Tan LM, Xu XJ, He BM, Luo C, Yin JY, Li X, Zhang W, Zhou HH, Liu ZQ. The role of single strand break repair pathways in cellular responses to camptothecin induced DNA damage. Biomed Pharmacother 2020; 125:109875. [DOI: 10.1016/j.biopha.2020.109875] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/24/2019] [Accepted: 01/06/2020] [Indexed: 12/12/2022] Open
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Kellner V, Luke B. Molecular and physiological consequences of faulty eukaryotic ribonucleotide excision repair. EMBO J 2020; 39:e102309. [PMID: 31833079 PMCID: PMC6996501 DOI: 10.15252/embj.2019102309] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 10/22/2019] [Accepted: 11/26/2019] [Indexed: 01/11/2023] Open
Abstract
The duplication of the eukaryotic genome is an intricate process that has to be tightly safe-guarded. One of the most frequently occurring errors during DNA synthesis is the mis-insertion of a ribonucleotide instead of a deoxyribonucleotide. Ribonucleotide excision repair (RER) is initiated by RNase H2 and results in error-free removal of such mis-incorporated ribonucleotides. If left unrepaired, DNA-embedded ribonucleotides result in a variety of alterations within chromosomal DNA, which ultimately lead to genome instability. Here, we review how genomic ribonucleotides lead to chromosomal aberrations and discuss how the tight regulation of RER timing may be important for preventing unwanted DNA damage. We describe the structural impact of unrepaired ribonucleotides on DNA and chromatin and comment on the potential consequences for cellular fitness. In the context of the molecular mechanisms associated with faulty RER, we have placed an emphasis on how and why increased levels of genomic ribonucleotides are associated with severe autoimmune syndromes, neuropathology, and cancer. In addition, we discuss therapeutic directions that could be followed for pathologies associated with defective removal of ribonucleotides from double-stranded DNA.
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Affiliation(s)
- Vanessa Kellner
- Institute of Molecular Biology (IMB)MainzGermany
- Present address:
Department of BiologyNew York UniversityNew YorkNYUSA
| | - Brian Luke
- Institute of Molecular Biology (IMB)MainzGermany
- Institute of Developmental Biology and Neurobiology (IDN)Johannes Gutenberg UniversitätMainzGermany
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11
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Tumbale PP, Jurkiw TJ, Schellenberg MJ, Riccio AA, O'Brien PJ, Williams RS. Two-tiered enforcement of high-fidelity DNA ligation. Nat Commun 2019; 10:5431. [PMID: 31780661 PMCID: PMC6882888 DOI: 10.1038/s41467-019-13478-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 11/05/2019] [Indexed: 01/07/2023] Open
Abstract
DNA ligases catalyze the joining of DNA strands to complete DNA replication, recombination and repair transactions. To protect the integrity of the genome, DNA ligase 1 (LIG1) discriminates against DNA junctions harboring mutagenic 3'-DNA mismatches or oxidative DNA damage, but how such high-fidelity ligation is enforced is unknown. Here, X-ray structures and kinetic analyses of LIG1 complexes with undamaged and oxidatively damaged DNA unveil that LIG1 employs Mg2+-reinforced DNA binding to validate DNA base pairing during the adenylyl transfer and nick-sealing ligation reaction steps. Our results support a model whereby LIG1 fidelity is governed by a high-fidelity (HiFi) interface between LIG1, Mg2+, and the DNA substrate that tunes the enzyme to release pro-mutagenic DNA nicks. In a second tier of protection, LIG1 activity is surveilled by Aprataxin (APTX), which suppresses mutagenic and abortive ligation at sites of oxidative DNA damage.
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Affiliation(s)
- Percy P Tumbale
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Thomas J Jurkiw
- Biological Chemistry, University of Michigan, 1150 W Medical Center Drive Ann Arbor, Ann Arbor, MI, 48109, USA
| | - Matthew J Schellenberg
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Amanda A Riccio
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Patrick J O'Brien
- Biological Chemistry, University of Michigan, 1150 W Medical Center Drive Ann Arbor, Ann Arbor, MI, 48109, USA.
| | - R Scott Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA.
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