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Zhang R, Zhang W, Wang C, Wen CK. Arabidopsis Fhit-like tumor suppressor resumes early terminated constitutive triple response1-10 mRNA translation. PLANT PHYSIOLOGY 2024; 195:2073-2093. [PMID: 38563472 DOI: 10.1093/plphys/kiae192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/09/2024] [Accepted: 02/14/2024] [Indexed: 04/04/2024]
Abstract
The Arabidopsis (Arabidopsis thaliana) constitutive triple response1-10 (ctr1-10) mutant produces a reduced level of CTR1 protein and exhibits a weak ctr1 mutant phenotype. Sequence analysis revealed highly active translation of the upstream open reading frame (uORF) at the extended 5'-UTR of the ctr1-10 mRNA, resulting from T-DNA insertion. Enhancer screening for ctr1-10 isolated the fragile histidine triad-1 (fhit-1) mutation. The fhit-1 ctr1-10 mutant phenotypically resembled strong ctr1 mutants and barely produced CTR1, and the fhit-1 mutation reduced the translation efficiency of ctr1-10 but not that of CTR1 mRNA. The human (Homo sapiens) Fhit that involves tumorigenesis and genome instability has the in vitro dinucleotide 5',5'″-P1, P3-triphosphate hydrolase activity, and expression of the human HsFHIT or the hydrolase-defective HsFHITH96N transgene reversed the fhit-1 ctr1-10 mutant phenotype and restored CTR1 levels. Genetic editing that in situ disrupts individual upstream ATG codons proximal to the ctr1-10 mORF elevated CTR1 levels in ctr1-10 plants independent of FHIT. EUKARYOTIC INITIATION FACTOR3G (eIF3G), which is involved in translation and reinitiation, interacted with FHIT, and both were associated with the polysome. We propose that FHIT resumes early terminated ctr1-10 mORF translation in the face of active and complex uORF translation. Our study unveils a niche that may lead to investigations on the molecular mechanism of Fhit-like proteins in translation reinitiation. The biological significance of FHIT-regulated translation is discussed.
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Affiliation(s)
- Ranran Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Wei Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Chenrunshu Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Chi-Kuang Wen
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
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2
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Madsen HB, Pease LI, Scanlan RL, Akbari M, Rasmussen LJ, Shanley DP, Bohr VA. The DNA repair enzyme, aprataxin, plays a role in innate immune signaling. Front Aging Neurosci 2023; 15:1290681. [PMID: 38161589 PMCID: PMC10754971 DOI: 10.3389/fnagi.2023.1290681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/20/2023] [Indexed: 01/03/2024] Open
Abstract
Ataxia with oculomotor apraxia type 1 (AOA1) is a progressive neurodegenerative disorder characterized by a gradual loss of coordination of hand movements, speech, and eye movements. AOA1 is caused by an inactivation mutation in the APTX gene. APTX resolves abortive DNA ligation intermediates. APTX deficiency may lead to the accumulation of 5'-AMP termini, especially in the mitochondrial genome. The consequences of APTX deficiency includes impaired mitochondrial function, increased DNA single-strand breaks, elevated reactive oxygen species production, and altered mitochondrial morphology. All of these processes can cause misplacement of nuclear and mitochondrial DNA, which can activate innate immune sensors to elicit an inflammatory response. This study explores the impact of APTX knockout in microglial cells, the immune cells of the brain. RNA-seq analysis revealed significant differences in the transcriptomes of wild-type and APTX knockout cells, especially in response to viral infections and innate immune pathways. Specifically, genes and proteins involved in the cGAS-STING and RIG-I/MAVS pathways were downregulated in APTX knockout cells, which suggests an impaired immune response to cytosolic DNA and RNA. The clinical relevance of these findings was supported by analyzing publicly available RNA-seq data from AOA1 patient cell lines. Comparisons between APTX-deficient patient cells and healthy control cells also revealed altered immune responses and dysregulated DNA- and RNA-sensing pathways in the patient cells. Overall, this study highlights the critical role of APTX in regulating innate immunity, particularly in DNA- and RNA-sensing pathways. Our findings contribute to a better understanding of the underlying molecular mechanisms of AOA1 pathology and highlights potential therapeutic targets for this disease.
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Affiliation(s)
- Helena B. Madsen
- Center for Healthy Aging, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Louise I. Pease
- CAMPUS for Ageing and Vitality, Newcastle University, Newcastle, United Kingdom
| | | | - Mansour Akbari
- Center for Healthy Aging, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Lene J. Rasmussen
- Center for Healthy Aging, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Daryl P. Shanley
- CAMPUS for Ageing and Vitality, Newcastle University, Newcastle, United Kingdom
| | - Vilhelm A. Bohr
- Center for Healthy Aging, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
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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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4
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Rong Z, Tu P, Xu P, Sun Y, Yu F, Tu N, Guo L, Yang Y. The Mitochondrial Response to DNA Damage. Front Cell Dev Biol 2021; 9:669379. [PMID: 34055802 PMCID: PMC8149749 DOI: 10.3389/fcell.2021.669379] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 04/20/2021] [Indexed: 01/08/2023] Open
Abstract
Mitochondria are double membrane organelles in eukaryotic cells that provide energy by generating adenosine triphosphate (ATP) through oxidative phosphorylation. They are crucial to many aspects of cellular metabolism. Mitochondria contain their own DNA that encodes for essential proteins involved in the execution of normal mitochondrial functions. Compared with nuclear DNA, the mitochondrial DNA (mtDNA) is more prone to be affected by DNA damaging agents, and accumulated DNA damages may cause mitochondrial dysfunction and drive the pathogenesis of a variety of human diseases, including neurodegenerative disorders and cancer. Therefore, understanding better how mtDNA damages are repaired will facilitate developing therapeutic strategies. In this review, we focus on our current understanding of the mtDNA repair system. We also discuss other mitochondrial events promoted by excessive DNA damages and inefficient DNA repair, such as mitochondrial fusion, fission, and mitophagy, which serve as quality control events for clearing damaged mtDNA.
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Affiliation(s)
- Ziye Rong
- Department of Immunology, School of Basic Medical Science, Anhui Medical University, Hefei, China
| | - Peipei Tu
- Department of Microbiology and Bioengineering, School of Life Sciences, Anhui Medical University, Hefei, China
| | - Peiqi Xu
- Department of Immunology, School of Basic Medical Science, Anhui Medical University, Hefei, China
| | - Yan Sun
- Department of Immunology, School of Basic Medical Science, Anhui Medical University, Hefei, China
| | - Fangfang Yu
- Department of Immunology, School of Basic Medical Science, Anhui Medical University, Hefei, China
| | - Na Tu
- Department of Immunology, School of Basic Medical Science, Anhui Medical University, Hefei, China
| | - Lixia Guo
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN, United States
| | - Yanan Yang
- Department of Immunology, School of Basic Medical Science, Anhui Medical University, Hefei, China
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5
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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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6
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Abstract
The Escherichia coli microcin C (McC) and related compounds are potent Trojan horse peptide-nucleotide antibiotics. The peptide part facilitates transport into sensitive cells. Inside the cell, the peptide part is degraded by nonspecific peptidases releasing an aspartamide-adenylate containing a phosphoramide bond. This nonhydrolyzable compound inhibits aspartyl-tRNA synthetase. In addition to the efficient export of McC outside the producing cells, special mechanisms have evolved to avoid self-toxicity caused by the degradation of the peptide part inside the producers. Here, we report that histidine-triad (HIT) hydrolases encoded in biosynthetic clusters of some McC homologs or by standalone genes confer resistance to McC-like compounds by hydrolyzing the phosphoramide bond in toxic aspartamide-adenosine, rendering them inactive.IMPORTANCE Uncovering the mechanisms of resistance is a required step for countering the looming antibiotic resistance crisis. In this communication, we show how universally conserved histidine-triad hydrolases provide resistance to microcin C, a potent inhibitor of bacterial protein synthesis.
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7
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Role of Rad51 and DNA repair in cancer: A molecular perspective. Pharmacol Ther 2020; 208:107492. [PMID: 32001312 DOI: 10.1016/j.pharmthera.2020.107492] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/13/2020] [Accepted: 01/22/2020] [Indexed: 12/24/2022]
Abstract
The maintenance of genome integrity is essential for any organism survival and for the inheritance of traits to offspring. To the purpose, cells have developed a complex DNA repair system to defend the genetic information against both endogenous and exogenous sources of damage. Accordingly, multiple repair pathways can be aroused from the diverse forms of DNA lesions, which can be effective per se or via crosstalk with others to complete the whole DNA repair process. Deficiencies in DNA healing resulting in faulty repair and/or prolonged DNA damage can lead to genes mutations, chromosome rearrangements, genomic instability, and finally carcinogenesis and/or cancer progression. Although it might seem paradoxical, at the same time such defects in DNA repair pathways may have therapeutic implications for potential clinical practice. Here we provide an overview of the main DNA repair pathways, with special focus on the role played by homologous repair and the RAD51 recombinase protein in the cellular DNA damage response. We next discuss the recombinase structure and function per se and in combination with all its principal mediators and regulators. Finally, we conclude with an analysis of the manifold roles that RAD51 plays in carcinogenesis, cancer progression and anticancer drug resistance, and conclude this work with a survey of the most promising therapeutic strategies aimed at targeting RAD51 in experimental oncology.
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8
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HINT1 in Neuropsychiatric Diseases: A Potential Neuroplastic Mediator. Neural Plast 2017; 2017:5181925. [PMID: 29214080 PMCID: PMC5682914 DOI: 10.1155/2017/5181925] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 08/23/2017] [Accepted: 09/18/2017] [Indexed: 01/25/2023] Open
Abstract
Although many studies have investigated the functions of histidine triad nucleotide-binding protein 1 (HINT1), its roles in neurobiological processes remain to be fully elucidated. As a member of the histidine triad (HIT) enzyme superfamily, HINT1 is distributed in almost every organ and has both enzymatic and nonenzymatic activity. Accumulating clinical and preclinical evidence suggests that HINT1 may play an important role as a neuroplastic mediator in neuropsychiatric diseases, such as schizophrenia, inherited peripheral neuropathies, mood disorders, and drug addiction. Though our knowledge of HINT1 is limited, it is believed that further research on the neuropathological functions of HINT1 would eventually benefit patients with neuropsychiatric and even psychosomatic diseases.
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9
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Shah R, Chou TF, Maize KM, Strom A, Finzel BC, Wagner CR. Inhibition by divalent metal ions of human histidine triad nucleotide binding protein1 (hHint1), a regulator of opioid analgesia and neuropathic pain. Biochem Biophys Res Commun 2017; 491:760-766. [DOI: 10.1016/j.bbrc.2017.07.111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 07/18/2017] [Accepted: 07/20/2017] [Indexed: 01/13/2023]
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10
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Lange S, Hacker SM, Schmid P, Scheffner M, Marx A. Small-Molecule Inhibitors of the Tumor Suppressor Fhit. Chembiochem 2017. [PMID: 28643453 DOI: 10.1002/cbic.201700226] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The tumor suppressor Fhit and its substrate diadenosine triphosphate (Ap3 A) are important factors in cancer development and progression. Fhit has Ap3 A hydrolase activity and cleaves Ap3 A into adenosine monophosphate (AMP) and adenosine diphosphate (ADP); this is believed to terminate Fhit-mediated signaling. How the catalytic activity of Fhit is regulated and how the Fhit⋅Ap3 A complex might exert its growth-suppressive function remain to be discovered. Small-molecule inhibitors of the enzymatic activity of Fhit would provide valuable tools for the elucidation of its tumor-suppressive functions. Here we describe the development of a high-throughput screen for the identification of such small-molecule inhibitors of Fhit. Two clusters of inhibitors that decreased the activity of Fhit by at least 90 % were identified. Several derivatives were synthesized and exhibited in vitro IC50 values in the nanomolar range.
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Affiliation(s)
- Sandra Lange
- Department of Chemistry, Konstanz Research School-Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany
| | - Stephan M Hacker
- Department of Chemistry, Konstanz Research School-Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany
- Department of Chemical Physiology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Philipp Schmid
- Department of Chemistry, Konstanz Research School-Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany
| | - Martin Scheffner
- Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany
| | - Andreas Marx
- Department of Chemistry, Konstanz Research School-Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany
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11
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Jiang B, Glover JNM, Weinfeld M. Neurological disorders associated with DNA strand-break processing enzymes. Mech Ageing Dev 2016; 161:130-140. [PMID: 27470939 DOI: 10.1016/j.mad.2016.07.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/21/2016] [Accepted: 07/23/2016] [Indexed: 12/24/2022]
Abstract
The termini of DNA strand breaks induced by reactive oxygen species or by abortive DNA metabolic intermediates require processing to enable subsequent gap filling and ligation to proceed. The three proteins, tyrosyl DNA-phosphodiesterase 1 (TDP1), aprataxin (APTX) and polynucleotide kinase/phosphatase (PNKP) each act on a discrete set of modified strand-break termini. Recently, a series of neurodegenerative and neurodevelopmental disorders have been associated with mutations in the genes coding for these proteins. Mutations in TDP1 and APTX have been linked to Spinocerebellar ataxia with axonal neuropathy (SCAN1) and Ataxia-ocular motor apraxia 1 (AOA1), respectively, while mutations in PNKP are considered to be responsible for Microcephaly with seizures (MCSZ) and Ataxia-ocular motor apraxia 4 (AOA4). Here we present an overview of the mechanisms of these proteins and how their impairment may give rise to their respective disorders.
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Affiliation(s)
- Bingcheng Jiang
- Department of Oncology, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, T6G 1Z2, Canada.
| | - J N Mark Glover
- Department of Biochemistry, Medical Sciences Building, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.
| | - Michael Weinfeld
- Department of Oncology, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, T6G 1Z2, Canada.
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Marriott AS, Vasieva O, Fang Y, Copeland NA, McLennan AG, Jones NJ. NUDT2 Disruption Elevates Diadenosine Tetraphosphate (Ap4A) and Down-Regulates Immune Response and Cancer Promotion Genes. PLoS One 2016; 11:e0154674. [PMID: 27144453 PMCID: PMC4856261 DOI: 10.1371/journal.pone.0154674] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 04/18/2016] [Indexed: 01/04/2023] Open
Abstract
Regulation of gene expression is one of several roles proposed for the stress-induced nucleotide diadenosine tetraphosphate (Ap4A). We have examined this directly by a comparative RNA-Seq analysis of KBM-7 chronic myelogenous leukemia cells and KBM-7 cells in which the NUDT2 Ap4A hydrolase gene had been disrupted (NuKO cells), causing a 175-fold increase in intracellular Ap4A. 6,288 differentially expressed genes were identified with P < 0.05. Of these, 980 were up-regulated and 705 down-regulated in NuKO cells with a fold-change ≥ 2. Ingenuity® Pathway Analysis (IPA®) was used to assign these genes to known canonical pathways and functional networks. Pathways associated with interferon responses, pattern recognition receptors and inflammation scored highly in the down-regulated set of genes while functions associated with MHC class II antigens were prominent among the up-regulated genes, which otherwise showed little organization into major functional gene sets. Tryptophan catabolism was also strongly down-regulated as were numerous genes known to be involved in tumor promotion in other systems, with roles in the epithelial-mesenchymal transition, proliferation, invasion and metastasis. Conversely, some pro-apoptotic genes were up-regulated. Major upstream factors predicted by IPA® for gene down-regulation included NFκB, STAT1/2, IRF3/4 and SP1 but no major factors controlling gene up-regulation were identified. Potential mechanisms for gene regulation mediated by Ap4A and/or NUDT2 disruption include binding of Ap4A to the HINT1 co-repressor, autocrine activation of purinoceptors by Ap4A, chromatin remodeling, effects of NUDT2 loss on transcript stability, and inhibition of ATP-dependent regulatory factors such as protein kinases by Ap4A. Existing evidence favors the last of these as the most probable mechanism. Regardless, our results suggest that the NUDT2 protein could be a novel cancer chemotherapeutic target, with its inhibition potentially exerting strong anti-tumor effects via multiple pathways involving metastasis, invasion, immunosuppression and apoptosis.
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MESH Headings
- Cell Line, Tumor
- Dinucleoside Phosphates/metabolism
- Down-Regulation
- Gene Expression Profiling
- Gene Knockout Techniques
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/immunology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Phosphoric Monoester Hydrolases/deficiency
- Phosphoric Monoester Hydrolases/genetics
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Affiliation(s)
- Andrew S. Marriott
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, Merseyside, United Kingdom
| | - Olga Vasieva
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Liverpool, Merseyside, United Kingdom
| | - Yongxiang Fang
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Liverpool, Merseyside, United Kingdom
| | - Nikki A. Copeland
- Division of Biomedical and Life Sciences, University of Lancaster, Lancaster, Lancashire, United Kingdom
| | - Alexander G. McLennan
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, Merseyside, United Kingdom
- * E-mail: (AGM); (NJJ)
| | - Nigel J. Jones
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, Merseyside, United Kingdom
- * E-mail: (AGM); (NJJ)
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Tarique KF, Devi S, Abdul Rehman SA, Gourinath S. Crystal structure of HINT from Helicobacter pylori. Acta Crystallogr F Struct Biol Commun 2016; 72:42-8. [PMID: 26750483 PMCID: PMC4708049 DOI: 10.1107/s2053230x15023316] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 12/04/2015] [Indexed: 11/10/2022] Open
Abstract
Proteins belonging to the histidine triad (HIT) superfamily bind nucleotides and use the histidine triad motif to carry out dinucleotidyl hydrolase, nucleotidyltransferase and phosphoramidite hydrolase activities. Five different branches of this superfamily are known to exist. Defects in these proteins in humans are linked to many diseases such as ataxia, diseases of RNA metabolism and cell-cycle regulation, and various types of cancer. The histidine triad nucleotide protein (HINT) is nearly identical to proteins that have been classified as protein kinase C-interacting proteins (PKCIs), which also have the ability to bind and inhibit protein kinase C. The structure of HINT, which exists as a homodimer, is highly conserved from humans to bacteria and shares homology with the product of fragile histidine triad protein (FHit), a tumour suppressor gene of this superfamily. Here, the structure of HINT from Helicobacter pylori (HpHINT) in complex with AMP is reported at a resolution of 3 Å. The final model has R and Rfree values of 26 and 28%, respectively, with good electron density. Structural comparison with previously reported homologues and phylogenetic analysis shows H. pylori HINT to be the smallest among them, and suggests that it branched out separately during the course of evolution. Overall, this structure has contributed to a better understanding of this protein across the animal kingdom.
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Affiliation(s)
- K. F. Tarique
- School of Life Science, Jawaharlal Nehru University, New Delhi, Delhi 110 067, India
| | - S. Devi
- School of Life Science, Jawaharlal Nehru University, New Delhi, Delhi 110 067, India
| | - S. A. Abdul Rehman
- School of Life Science, Jawaharlal Nehru University, New Delhi, Delhi 110 067, India
| | - S. Gourinath
- School of Life Science, Jawaharlal Nehru University, New Delhi, Delhi 110 067, India
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Akbari M, Sykora P, Bohr VA. Slow mitochondrial repair of 5'-AMP renders mtDNA susceptible to damage in APTX deficient cells. Sci Rep 2015; 5:12876. [PMID: 26256098 PMCID: PMC4530458 DOI: 10.1038/srep12876] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 07/09/2015] [Indexed: 12/22/2022] Open
Abstract
Aborted DNA ligation events in eukaryotic cells can generate 5'-adenylated (5'-AMP) DNA termini that can be removed from DNA by aprataxin (APTX). Mutations in APTX cause an inherited human disease syndrome characterized by early-onset progressive ataxia with ocular motor apraxia (AOA1). APTX is found in the nuclei and mitochondria of eukaryotic cells. Depletion of APTX causes mitochondrial dysfunction and renders the mitochondrial genome, but not the nuclear genome susceptible to damage. The biochemical processes that link APTX deficiency to mitochondrial dysfunction have not been well elucidated. Here, we monitored the repair of 5'-AMP DNA damage in nuclear and mitochondrial extracts from human APTX(+/+) and APTX(-/-) cells. The efficiency of repair of 5'-AMP DNA was much lower in mitochondrial than in nuclear protein extracts, and resulted in persistent DNA repair intermediates in APTX deficient cells. Moreover, the removal of 5'-AMP from DNA was significantly slower in the mitochondrial extracts from human cell lines and mouse tissues compared with their corresponding nuclear extracts. These results suggest that, contrary to nuclear DNA repair, mitochondrial DNA repair is not able to compensate for APTX deficiency resulting in the accumulation of mitochondrial DNA damage.
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Affiliation(s)
- Mansour Akbari
- Center for Healthy Aging, SUND, University of Copenhagen, Denmark
| | - Peter Sykora
- Laboratory of Molecular Gerontology, National Institute on Aging, 251 Bayview Blvd, Baltimore, USA
| | - Vilhelm A Bohr
- 1] Center for Healthy Aging, SUND, University of Copenhagen, Denmark [2] Laboratory of Molecular Gerontology, National Institute on Aging, 251 Bayview Blvd, Baltimore, USA
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15
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Hanaoka K, Tanaka W, Kayanuma M, Shoji M. A QM/MM study of the 5′-AMP DNA hydrolysis of aprataxin. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.04.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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16
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Marriott AS, Copeland NA, Cunningham R, Wilkinson MC, McLennan AG, Jones NJ. Diadenosine 5', 5'''-P(1),P(4)-tetraphosphate (Ap4A) is synthesized in response to DNA damage and inhibits the initiation of DNA replication. DNA Repair (Amst) 2015. [PMID: 26204256 DOI: 10.1016/j.dnarep.2015.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The level of intracellular diadenosine 5', 5'''-P(1),P(4)-tetraphosphate (Ap4A) increases several fold in mammalian cells treated with non-cytotoxic doses of interstrand DNA-crosslinking agents such as mitomycin C. It is also increased in cells lacking DNA repair proteins including XRCC1, PARP1, APTX and FANCG, while >50-fold increases (up to around 25 μM) are achieved in repair mutants exposed to mitomycin C. Part of this induced Ap4A is converted into novel derivatives, identified as mono- and di-ADP-ribosylated Ap4A. Gene knockout experiments suggest that DNA ligase III is primarily responsible for the synthesis of damage-induced Ap4A and that PARP1 and PARP2 can both catalyze its ADP-ribosylation. Degradative proteins such as aprataxin may also contribute to the increase. Using a cell-free replication system, Ap4A was found to cause a marked inhibition of the initiation of DNA replicons, while elongation was unaffected. Maximum inhibition of 70-80% was achieved with 20 μM Ap4A. Ap3A, Ap5A, Gp4G and ADP-ribosylated Ap4A were without effect. It is proposed that Ap4A acts as an important inducible ligand in the DNA damage response to prevent the replication of damaged DNA.
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Affiliation(s)
- Andrew S Marriott
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Nikki A Copeland
- Division of Biomedical and Life Sciences, University of Lancaster, Lancaster LA1 4YG, UK
| | - Ryan Cunningham
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Mark C Wilkinson
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Alexander G McLennan
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
| | - Nigel J Jones
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
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17
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Garcia-Diaz B, Barca E, Balreira A, Lopez LC, Tadesse S, Krishna S, Naini A, Mariotti C, Castellotti B, Quinzii CM. Lack of aprataxin impairs mitochondrial functions via downregulation of the APE1/NRF1/NRF2 pathway. Hum Mol Genet 2015; 24:4516-29. [PMID: 25976310 DOI: 10.1093/hmg/ddv183] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 05/12/2015] [Indexed: 11/13/2022] Open
Abstract
Ataxia oculomotor apraxia type 1 (AOA1) is an autosomal recessive disease caused by mutations in APTX, which encodes the DNA strand-break repair protein aprataxin (APTX). CoQ10 deficiency has been identified in fibroblasts and muscle of AOA1 patients carrying the common W279X mutation, and aprataxin has been localized to mitochondria in neuroblastoma cells, where it enhances preservation of mitochondrial function. In this study, we show that aprataxin deficiency impairs mitochondrial function, independent of its role in mitochondrial DNA repair. The bioenergetics defect in AOA1-mutant fibroblasts and APTX-depleted Hela cells is caused by decreased expression of SDHA and genes encoding CoQ biosynthetic enzymes, in association with reductions of APE1, NRF1 and NRF2. The biochemical and molecular abnormalities in APTX-depleted cells are recapitulated by knockdown of APE1 in Hela cells and are rescued by overexpression of NRF1/2. Importantly, pharmacological upregulation of NRF1 alone by 5-aminoimidazone-4-carboxamide ribonucleotide does not rescue the phenotype, which, in contrast, is reversed by the upregulation of NRF2 by rosiglitazone. Accordingly, we propose that the lack of aprataxin causes reduction of the pathway APE1/NRF1/NRF2 and their target genes. Our findings demonstrate a critical role of APTX in transcription regulation of mitochondrial function and the pathogenesis of AOA1 via a novel pathomechanistic pathway, which may be relevant to other neurodegenerative diseases.
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Affiliation(s)
| | - Emanuele Barca
- Department of Neurology, UOC of Neurology and Neuromuscular Disorders, Department of Neuroscience, University of Messina, Messina 98100, Italy
| | | | - Luis C Lopez
- Department of Neurology, Institute of Biotechnology, Biomedical Research Center (CIBM), Health Science Technological Park (PTS), University of Granada, Armilla, Granada 18100, Spain and
| | | | - Sindhu Krishna
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Ali Naini
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Caterina Mariotti
- Unitâ di Genetica delle Malattie Neurodegenerative e Metaboliche, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', Milan 20126, Italy
| | - Barbara Castellotti
- Unitâ di Genetica delle Malattie Neurodegenerative e Metaboliche, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', Milan 20126, Italy
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18
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Schellenberg MJ, Tumbale PP, Williams RS. Molecular underpinnings of Aprataxin RNA/DNA deadenylase function and dysfunction in neurological disease. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 117:157-165. [PMID: 25637650 DOI: 10.1016/j.pbiomolbio.2015.01.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 01/12/2015] [Accepted: 01/18/2015] [Indexed: 11/30/2022]
Abstract
Eukaryotic DNA ligases seal DNA breaks in the final step of DNA replication and repair transactions via a three-step reaction mechanism that can abort if DNA ligases encounter modified DNA termini, such as the products and repair intermediates of DNA oxidation, alkylation, or the aberrant incorporation of ribonucleotides into genomic DNA. Such abortive DNA ligation reactions act as molecular checkpoint for DNA damage and create 5'-adenylated nucleic acid termini in the context of DNA and RNA-DNA substrates in DNA single strand break repair (SSBR) and ribonucleotide excision repair (RER). Aprataxin (APTX), a protein altered in the heritable neurological disorder Ataxia with Oculomotor Apraxia 1 (AOA1), acts as a DNA ligase "proofreader" to directly reverse AMP-modified nucleic acid termini in DNA- and RNA-DNA damage responses. Herein, we survey APTX function and the emerging cell biological, structural and biochemical data that has established a molecular foundation for understanding the APTX mediated deadenylation reaction, and is providing insights into the molecular bases of APTX deficiency in AOA1.
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Affiliation(s)
- Matthew J Schellenberg
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, 27709, USA
| | - Percy P Tumbale
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, 27709, USA
| | - R Scott Williams
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, 27709, USA
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19
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Aprataxin resolves adenylated RNA-DNA junctions to maintain genome integrity. Nature 2013; 506:111-5. [PMID: 24362567 PMCID: PMC4064939 DOI: 10.1038/nature12824] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 10/31/2013] [Indexed: 01/10/2023]
Abstract
Faithful maintenance and propagation of eukaryotic genomes is ensured by three-step DNA ligation reactions employed by ATP-dependent DNA ligases1,2. Paradoxically, when DNA ligases encounter nicked DNA structures with abnormal DNA termini, DNA ligase catalytic activity can generate and/or exacerbate DNA damage through abortive ligation that produces chemically adducted, toxic 5′-adenylated (5′-AMP) DNA lesions3–6 (Fig. 1a). Aprataxin (Aptx) reverses DNA-adenylation but the context for deadenylation repair is unclear. Here we examine the importance of Aptx to RNaseH2-dependent excision repair (RER) of a lesion that is very frequently introduced into DNA, a ribonucleotide. We show that ligases generate adenylated 5′-ends containing a ribose characteristic of RNaseH2 incision. Aptx efficiently repairs adenylated RNA-DNA, and acting in an RNA-DNA damage response (RDDR), promotes cellular survival and prevents S-phase checkpoint activation in budding yeast undergoing RER. Structure-function studies of human Aptx/RNA-DNA/AMP/Zn complexes define a mechanism for detecting and reversing adenylation at RNA-DNA junctions. This involves A-form RNA-binding, proper protein folding and conformational changes, all of which are impacted by heritable APTX mutations in Ataxia with Oculomotor Apraxia 1 (AOA1). Together, these results suggest that accumulation of adenylated RNA-DNA may contribute to neurological disease.
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20
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Structures of yeast Apa2 reveal catalytic insights into a canonical AP₄A phosphorylase of the histidine triad superfamily. J Mol Biol 2013; 425:2687-98. [PMID: 23628156 DOI: 10.1016/j.jmb.2013.04.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/17/2013] [Accepted: 04/19/2013] [Indexed: 11/23/2022]
Abstract
The homeostasis of intracellular diadenosine 5',5″'-P(1),P(4)-tetraphosphate (Ap4A) in the yeast Saccharomyces cerevisiae is maintained by two 60% sequence-identical paralogs of Ap4A phosphorylases (Apa1 and Apa2). Enzymatic assays show that, compared to Apa1, Apa2 has a relatively higher phosphorylase activity towards Ap3A (5',5″'-P(1),P(3)-tetraphosphate), Ap4A, and Ap5A (5',5″'-P(1),P(5)-tetraphosphate), and Ap4A is the favorable substrate for both enzymes. To decipher the catalytic insights, we determined the crystal structures of Apa2 in the apo-, AMP-, and Ap4A-complexed forms at 2.30, 2.80, and 2.70Å resolution, respectively. Apa2 is an α/β protein with a core domain of a twisted eight-stranded antiparallel β-sheet flanked by several α-helices, similar to the galactose-1-phosphate uridylyltransferase (GalT) members of the histidine triad (HIT) superfamily. However, a unique auxiliary domain enables an individual Apa2 monomer to possess an intact substrate-binding cleft, which is distinct from previously reported dimeric GalT proteins. This cleft is perfectly complementary to the favorable substrate Ap4A, the AMP and ATP moieties of which are perpendicular to each other, leaving the α-phosphate group exposed at the sharp turn against the catalytic residue His161. Structural comparisons combined with site-directed mutagenesis and activity assays enable us to define the key residues for catalysis. Furthermore, multiple-sequence alignment reveals that Apa2 and homologs represent canonical Ap4A phosphorylases, which could be grouped as a unique branch in the GalT family.
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21
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Structure of an aprataxin-DNA complex with insights into AOA1 neurodegenerative disease. Nat Struct Mol Biol 2011; 18:1189-95. [PMID: 21984210 PMCID: PMC3210380 DOI: 10.1038/nsmb.2146] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 07/27/2011] [Indexed: 01/04/2023]
Abstract
DNA ligases finalize DNA replication and repair through DNA nick-sealing reactions that can abort to generate cytotoxic 5'-adenylation DNA damage. Aprataxin (Aptx) catalyzes direct reversal of 5'-adenylate adducts to protect genome integrity. Here the structure of a Schizosaccharomyces pombe Aptx-DNA-AMP-Zn(2+) complex reveals active site and DNA interaction clefts formed by fusing a histidine triad (HIT) nucleotide hydrolase with a DNA minor groove-binding C(2)HE zinc finger (Znf). An Aptx helical 'wedge' interrogates the base stack for sensing DNA ends or DNA nicks. The HIT-Znf, the wedge and an '[F/Y]PK' pivot motif cooperate to distort terminal DNA base-pairing and direct 5'-adenylate into the active site pocket. Structural and mutational data support a wedge-pivot-cut HIT-Znf catalytic mechanism for 5'-adenylate adduct recognition and removal and suggest that mutations affecting protein folding, the active site pocket and the pivot motif underlie Aptx dysfunction in the neurodegenerative disorder ataxia with oculomotor apraxia 1 (AOA1).
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22
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Crystal structures of aprataxin ortholog Hnt3 reveal the mechanism for reversal of 5'-adenylated DNA. Nat Struct Mol Biol 2011; 18:1297-9. [PMID: 21984208 DOI: 10.1038/nsmb.2145] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 07/25/2011] [Indexed: 02/06/2023]
Abstract
Aprataxin is a DNA deadenylase that resolves DNA 5'-AMP termini and reverses abortive DNA ligation. The crystal structures of Schizosaccharomyces pombe aprataxin Hnt3 in its apo form and in complex to dsDNA and dsDNA-AMP reveal how Hnt3 recognizes and processes 5'-adenylated DNA in a structure-specific manner. The bound DNA adopts a 5'-flap conformation that facilitates 5'-AMP access to the active site, where AMP cleavage occurs by a canonical catalytic mechanism.
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23
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Dolot R, Ozga M, Krakowiak A, Nawrot B. High-resolution X-ray structure of the rabbit histidine triad nucleotide-binding protein 1 (rHINT1)–adenosine complex at 1.10 Å resolution. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2011; 67:601-7. [DOI: 10.1107/s0907444911015605] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 04/25/2011] [Indexed: 11/11/2022]
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24
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Aprataxin localizes to mitochondria and preserves mitochondrial function. Proc Natl Acad Sci U S A 2011; 108:7437-42. [PMID: 21502511 DOI: 10.1073/pnas.1100084108] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Ataxia with oculomotor apraxia 1 is caused by mutation in the APTX gene, which encodes the DNA strand-break repair protein aprataxin. Aprataxin exhibits homology to the histidine triad superfamily of nucleotide hydrolases and transferases and removes 5'-adenylate groups from DNA that arise from aborted ligation reactions. We report herein that aprataxin localizes to mitochondria in human cells and we identify an N-terminal amino acid sequence that targets certain isoforms of the protein to this intracellular compartment. We also show that transcripts encoding this unique N-terminal stretch are expressed in the human brain, with highest production in the cerebellum. Depletion of aprataxin in human SH-SY5Y neuroblastoma cells and primary skeletal muscle myoblasts results in mitochondrial dysfunction, which is revealed by reduced citrate synthase activity and mtDNA copy number. Moreover, mtDNA, not nuclear DNA, was found to have higher levels of background DNA damage on aprataxin knockdown, suggesting a direct role for the enzyme in mtDNA processing.
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25
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Martin J, St-Pierre MV, Dufour JF. Hit proteins, mitochondria and cancer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:626-32. [PMID: 21316334 DOI: 10.1016/j.bbabio.2011.02.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 02/02/2011] [Accepted: 02/02/2011] [Indexed: 11/30/2022]
Abstract
The histidine triad (HIT) superfamily comprises proteins that share the histidine triad motif, His-ϕ-His-ϕ-His-ϕ-ϕ, where ϕ is a hydrophobic amino acid. HIT proteins are ubiquitous in prokaryotes and eukaryotes. HIT proteins bind nucleotides and exert dinucleotidyl hydrolase, nucleotidylyl transferase or phosphoramidate hydrolase enzymatic activity. In humans, 5 families of HIT proteins are recognized. The accumulated epidemiological and experimental evidence indicates that two branches of the superfamily, the HINT (Histidine Triad Nucleotide Binding) members and FHIT (Fragile Histidine Triad), have tumor suppressor properties but a conclusive physiological role can still not be assigned to these proteins. Aprataxin forms another discrete branch of the HIT superfamily, is implicated in DNA repair mechanisms and unlike the HINT and FHIT members, a defective protein can be conclusively linked to a disease, ataxia with oculomotor apraxia type 1. The scavenger mRNA decapping enzyme, DcpS, forms a fourth branch of the HIT superfamily. Finally, the GalT enzymes, which exert specific nucleoside monophosphate transferase activity, form a fifth branch that is not implicated in tumorigenesis. The molecular mechanisms by which the HINT and FHIT proteins participate in bioenergetics of cancer are just beginning to be unraveled. Their purported actions as tumor suppressors are highlighted in this review.
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Affiliation(s)
- Juliette Martin
- Institute of Clinical Pharmacology and Visceral Research, University of Bern, Switzerland
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26
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El-Khamisy SF. To live or to die: a matter of processing damaged DNA termini in neurons. EMBO Mol Med 2011; 3:78-88. [PMID: 21246735 PMCID: PMC3377058 DOI: 10.1002/emmm.201000114] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 11/22/2010] [Accepted: 12/08/2010] [Indexed: 11/06/2022] Open
Abstract
Defects in the repair of deoxyribonucleic acid (DNA) damage underpin several hereditary neurological diseases in humans. Of the different activities that repair chromosomal DNA breaks, defects in resolving damaged DNA termini are among the most common causes of neuronal cell death. Here, the molecular mechanisms of some of the DNA end processing activities are reviewed and the association with human neurodegenerative disease is discussed.
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27
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Huebner K, Saldivar JC, Sun J, Shibata H, Druck T. Hits, Fhits and Nits: beyond enzymatic function. ACTA ACUST UNITED AC 2010; 51:208-17. [PMID: 21035495 DOI: 10.1016/j.advenzreg.2010.09.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 09/02/2010] [Indexed: 11/29/2022]
Abstract
We have briefly summarized what is known about these proteins, but in closing wish to feature the outstanding questions. Hint1 was discovered mistakenly as an inhibitor of Protein Kinase C and designated Pkci, a designation that still confuses the literature. The other Hint family members were discovered by homology to Hint1. Aprataxin was discovered as a result of the hunt for a gene responsible for AOA1. Fhit was discovered through cloning of a familial chromosome translocation breakpoint on chromosome 3 that interrupts the large FHIT gene within an intron, in the FRA3B chromosome region (Ohta et al., 1996), now known to be the region of the human genome most susceptible to DNA damage due to replication stress (Durkin et al., 2008). The NitFhit fusion genewas discovered during searches for Fhit homologs in flies and worms because the fly/worm Nit polypeptide is fused to the 5'-end of the Fhit gene; the mammalian Nit gene family was discovered because of the NitFhit fusion gene, in searches for homologs to the Nit polypeptide of the NitFhit gene. Each of the Hit family member proteins is reported to have enzymatic activities toward putative substrates involving nucleosides or dinucleosides. Most surprisingly, each of the Hit family proteins discussed has been implicated in important DNA damage response pathways and/or tumor suppression pathways. And for each of them it has been difficult to assign definite substrates, to know if the substrates and catalytic products have biological functions, to know if that function is related to the DNA damage response and suppressor functions, and to precisely define the pathways through which tumor suppression occurs. When the fly Nit sequence was found at the 5'-end of the fly Fhit gene, this gene was hailed as a Rosetta stone gene/protein that would help in discovery of the function of Fhit, because the Nit protein should be in the same signal pathway (Pace et al., 2000). However, the mammalian Nit family proteins have turned out to be at least as mysterious as the Fhit proteins, with the Nit1 substrate still unknown and the surprising finding that Nit proteins also appear to behave as tumor suppressor proteins. Whether the predicted enzymatic functions of these proteins are relevant to the observed biological functions, remain among the outstanding unanswered puzzles and raise the question: have these mammalian proteins evolved beyond the putative original enzymatic purpose, such that the catalytic function is now vestigial and subservient to signal pathways that use the protein-substrate complexes in pathways that signal apoptosis or DNA damage response? Or can these proteins be fulfilling catalytic functions independently but in parallel with signal pathway functions, as perhaps observed for Aprataxin? Or is the catalytic function indeed part of the observed biological functions, such as apoptosis and tumor suppression? Perhaps the recent, post-genomic focus on metabolomics and genome-wide investigations of signal pathway networks will lead to answers to some of these outstanding questions.
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Affiliation(s)
- Kay Huebner
- Department of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University Medical Center, Columbus, OH 43210, United States.
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28
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Bardaweel S, Pace J, Chou TF, Cody V, Wagner CR. Probing the impact of the echinT C-terminal domain on structure and catalysis. J Mol Biol 2010; 404:627-38. [PMID: 20934431 DOI: 10.1016/j.jmb.2010.09.066] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2010] [Revised: 09/28/2010] [Accepted: 09/30/2010] [Indexed: 11/25/2022]
Abstract
Histidine triad nucleotide binding protein (Hint) is considered as the ancestor of the histidine triad protein superfamily and is highly conserved from bacteria to humans. Prokaryote genomes, including a wide array of both Gram-negative bacteria and Gram-positive bacteria, typically encode one Hint gene. The cellular function of Hint and the rationale for its evolutionary conservation in bacteria have remained a mystery. Despite its ubiquity and high sequence similarity to eukaryote Hint1 [Escherichia coli Hint (echinT) is 48% identical with human Hint1], prokaryote Hint has been reported in only a few studies. Here we report the first conformational information on the full-length N-terminal and C-terminal residues of Hint from the E. coli complex with GMP. Structural analysis of the echinT-GMP complex reveals that it crystallizes in the monoclinic space group P2(1) with four homodimers in the asymmetric unit. Analysis of electron density for both the N-terminal residues and the C-terminal residues of the echinT-GMP complex indicates that the loops in some monomers can adopt more than one conformation. The observation of conformational flexibility in terminal loop regions could explain the presence of multiple homodimers in the asymmetric unit of this structure. To explore the impact of the echinT C-terminus on protein structure and catalysis, we conducted a series of catalytic radiolabeling and kinetic experiments on the C-terminal deletion mutants of echinT. In this study, we show that sequential deletion of the C-terminus likely has no effect on homodimerization and a modest effect on the secondary structure of echinT. However, we observed a significant impact on the folding structure, as reflected by a significant lowering of the T(m) value. Kinetic analysis reveals that the C-terminal deletion mutants are within an order of magnitude less efficient in catalysis compared to wild type, while the overall kinetic mechanism that proceeds through a fast step, followed by a rate-limiting hydrolysis step, was conserved. Nevertheless, the ability of the C-terminal deletion mutants to hydrolyze lysyl-AMP generated by LysU was greatly impaired. Taken together, our results highlight the emerging role of the C-terminus in governing the catalytic function of Hints.
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Affiliation(s)
- Sanaa Bardaweel
- Department of Medicinal Chemistry, University of Minnesota, 8-174 Weaver Densford Hall, 308 Harvard Street SE, Minneapolis, MN 55455, USA
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29
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Saldivar JC, Shibata H, Huebner K. Pathology and biology associated with the fragile FHIT gene and gene product. J Cell Biochem 2010; 109:858-65. [PMID: 20082323 DOI: 10.1002/jcb.22481] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
More than 12 years and >800 scientific publications after the discovery of the first gene at a chromosome fragile site, the FHIT gene at FRA3B, there are still questions to pursue concerning the selective advantage conferred to cells by loss of expression of FHIT, the most frequent target of allele deletion in precancerous lesions and cancers. These questions are considered in light of recent investigations of genetic and epigenetic alterations to the locus and in a retrospective consideration of biological roles of the Fhit protein discovered through functional studies.
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Affiliation(s)
- Joshua C Saldivar
- Integrated Biomedical Science Graduate Program, Ohio State University Medical Center, Columbus, Ohio, USA
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30
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Daiou C, Christodoulou K, Xiromerisiou G, Panas M, Dardiotis E, Kladi A, Speletas M, Ntaios G, Papadimitriou A, Germenis A, Hadjigeorgiou GM. Absence of aprataxin gene mutations in a Greek cohort with sporadic early onset ataxia and normal GAA triplets in frataxin gene. Neurol Sci 2010; 31:393-7. [PMID: 19953284 DOI: 10.1007/s10072-009-0201-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2009] [Accepted: 11/17/2009] [Indexed: 12/19/2022]
Abstract
Phenotype of patients with the aprataxin gene mutation varies and according to previous studies, screening of aprataxin gene could be useful, once frataxin gene mutation is excluded in patients with normal GAA expansion in frataxin gene. In the present study, we sought to determine possible causative mutations in aprataxin gene (all exons and flanking intronic sequences) in 14 Greek patients with sporadic cerebellar ataxia all but one without GAA expansion in frataxin gene (1 patient was heterozygous). No detectable point mutation or deletion was found in the aprataxin gene of all the patients. Our results do not confirm the previous studies. This difference may be attributed to the different populations studied and possible different genetic background. It is still questionable whether the screening for aprataxin mutation in Greek patients' Friedreich ataxia phenotype is of clinical importance; larger, multicenter studies are necessary to clarify this issue.
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Affiliation(s)
- C Daiou
- Laboratory of Neurogenetics, Neuroscience Unit, Department of Neurology, Faculty of Medicine, University of Thessalia, Larissa, Greece
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31
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Becherel OJ, Jakob B, Cherry AL, Gueven N, Fusser M, Kijas AW, Peng C, Katyal S, McKinnon PJ, Chen J, Epe B, Smerdon SJ, Taucher-Scholz G, Lavin MF. CK2 phosphorylation-dependent interaction between aprataxin and MDC1 in the DNA damage response. Nucleic Acids Res 2010; 38:1489-503. [PMID: 20008512 PMCID: PMC2836575 DOI: 10.1093/nar/gkp1149] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 10/26/2009] [Accepted: 11/20/2009] [Indexed: 11/13/2022] Open
Abstract
Aprataxin, defective in the neurodegenerative disorder ataxia oculomotor apraxia type 1, resolves abortive DNA ligation intermediates during DNA repair. Here, we demonstrate that aprataxin localizes at sites of DNA damage induced by high LET radiation and binds to mediator of DNA-damage checkpoint protein 1 (MDC1/NFBD1) through a phosphorylation-dependent interaction. This interaction is mediated via the aprataxin FHA domain and multiple casein kinase 2 di-phosphorylated S-D-T-D motifs in MDC1. X-ray structural and mutagenic analysis of aprataxin FHA domain, combined with modelling of the pSDpTD peptide interaction suggest an unusual FHA binding mechanism mediated by a cluster of basic residues at and around the canonical pT-docking site. Mutation of aprataxin FHA Arg29 prevented its interaction with MDC1 and recruitment to sites of DNA damage. These results indicate that aprataxin is involved not only in single strand break repair but also in the processing of a subset of double strand breaks presumably through its interaction with MDC1.
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Affiliation(s)
- Olivier J. Becherel
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Burkhard Jakob
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Amy L. Cherry
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Nuri Gueven
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Markus Fusser
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Amanda W. Kijas
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Cheng Peng
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Sachin Katyal
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Peter J. McKinnon
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Junjie Chen
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Bernd Epe
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Stephen J. Smerdon
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Gisela Taucher-Scholz
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
| | - Martin F. Lavin
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, QLD 4029, Australia, GSI Helmholtzzentrum Schwerionenforschung GmBH, Planckstr. 1, 64291 Darmstadt, Germany, The MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK, Institute of Pharmacy, University of Mainz, Mainz, Germany, Department of Genetics and Tumor Cell Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA and Central Clinical Division, University of Queensland, Brisbane, Australia
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Wu L, Wu X, Deng H, Huang Y. First identification and functional analysis of a histidine triad nucleotide binding protein in an invertebrate species Haliotis diversicolor supertexta. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2010; 34:76-83. [PMID: 19720079 DOI: 10.1016/j.dci.2009.08.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 08/21/2009] [Accepted: 08/21/2009] [Indexed: 05/28/2023]
Abstract
Histidine triad nucleotide binding protein (HINT) represents the most ancient and widespread branches in the histidine triad superfamily. HINT plays an important role in many biological processes especially in cell biology, and it has been found in a wide variety of species. However, the functional attributes of HINT homologues in invertebrates have not yet been reported. Here we identified a HINT homologue in abalone, which we named ab-HINT. The ab-HINT shows significant structural and functional similarities to mammalian HINT. RT-PCR and western blot analysis show that ab-HINT is ubiquitously expressed in abalone tissues and highly expressed in hemocyte and gills. In addition, significant up-regulation of ab-HINT was observed after LPS or Poly I:C challenge. Immunostainings suggest that ab-HINT is expressed predominantly in epithelial cells and mainly localized in the cytoplasmic compartment. Studies of the effect on cell apoptosis indicate that ab-HINT can trigger hemocytes apoptosis and p53 is involved in this process. These results conclude that ab-HINT is involved in the immune response of abalone and may be a potential pro-apoptotic factor. To the best of our knowledge, this is the first identification and characterization of a HINT homologue in invertebrates.
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Affiliation(s)
- Liuji Wu
- Laboratory of Marine Life Science and Technology, College of Animal Sciences, Zhejiang University, 268 Kaixuan Road, Hangzhou 310029, PR China
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Tada M, Yokoseki A, Sato T, Makifuchi T, Onodera O. Early-onset ataxia with ocular motor apraxia and hypoalbuminemia/ataxia with oculomotor apraxia 1. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 685:21-33. [PMID: 20687492 DOI: 10.1007/978-1-4419-6448-9_3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA single-strand breaks (SSBs) are non-overlapping discontinuities in strands ofa DNA duplex. Significant attention has been given on the DNA SSB repair (SSBR) system in neurons, because the impairment of the SSBR causes human neurodegenerative disorders, including early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH), also known as ataxia-oculomotor apraxia Type 1 (AOA1). EAOH/AOA1 is characterized by early-onset slowly progressive ataxia, ocular motor apraxia, peripheral neuropathy and hypoalbuminemia. Neuropathological examination reveals severe loss of Purkinje cells and moderate neuronal loss in the anterior horn and dorsal root ganglia. EAOH/AOA1 is caused by the mutation in the APTX gene encoding the aprataxin (APTX) protein. APTX interacts with X-ray repair cross-complementing group 1 protein, which is a scaffold protein in SSBR. In addition, APTX-defective cells show increased sensitivity to genotoxic agents, which result in SSBs. These results indicate an important role ofAPTX in SSBR. SSBs are usually accompanied by modified or damaged 5'- and 3'-ends at the break site. Because these modified or damaged ends are not suitable for DNA ligation, they need to be restored to conventional ends prior to subsequent repair processes. APTX restores the 5'-adenylate monophosphate, 3'-phosphates and 3'-phosphoglycolate ends. The loss of function of APTX results in the accumulation of SSBs, consequently leading to neuronal cell dysfunction and death.
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Affiliation(s)
- Masayoshi Tada
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Japan
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34
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Abstract
AOA1 (ataxia oculomotor apraxia-1) results from mutations in aprataxin, a component of DNA strand break repair that removes AMP from 5'-termini. In the present article, we provide an overview of this disease and review recent experiments demonstrating that short-patch repair of oxidative single-strand breaks in AOA1 cell extracts bypasses the point of aprataxin action and stalls at the final step of DNA ligation, resulting in accumulation of adenylated DNA nicks. Strikingly, this defect results from insufficient levels of non-adenylated DNA ligase and short-patch single-strand break repair can be restored in AOA1 extracts, independently of aprataxin, by addition of recombinant DNA ligase.
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Harris JL, Jakob B, Taucher-Scholz G, Dianov GL, Becherel OJ, Lavin MF. Aprataxin, poly-ADP ribose polymerase 1 (PARP-1) and apurinic endonuclease 1 (APE1) function together to protect the genome against oxidative damage. Hum Mol Genet 2009; 18:4102-17. [PMID: 19643912 DOI: 10.1093/hmg/ddp359] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Aprataxin, defective in the neurodegenerative disorder ataxia oculomotor apraxia type 1 (AOA1), is a DNA repair protein that processes the product of abortive ligations, 5' adenylated DNA. In addition to its interaction with the single-strand break repair protein XRCC1, aprataxin also interacts with poly-ADP ribose polymerase 1 (PARP-1), a key player in the detection of DNA single-strand breaks. Here, we reveal reduced expression of PARP-1, apurinic endonuclease 1 (APE1) and OGG1 in AOA1 cells and demonstrate a requirement for PARP-1 in the recruitment of aprataxin to sites of DNA breaks. While inhibition of PARP activity did not affect aprataxin activity in vitro, it retarded its recruitment to sites of DNA damage in vivo. We also demonstrate the presence of elevated levels of oxidative DNA damage in AOA1 cells coupled with reduced base excision and gap filling repair efficiencies indicative of a synergy between aprataxin, PARP-1, APE-1 and OGG1 in the DNA damage response. These data support both direct and indirect modulating functions for aprataxin on base excision repair.
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Affiliation(s)
- Janelle L Harris
- Queensland Institute of Medical Research, Radiation Biology and Oncology, Brisbane, Queensland 4029, Australia
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36
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Ye ZY, Hou QM, Li LF, Su XD. Crystallization and preliminary X-ray crystallographic analysis of SMU.412c protein from the caries pathogen Streptococcus mutans. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009; 65:392-4. [PMID: 19342789 PMCID: PMC2664769 DOI: 10.1107/s1744309109009464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 03/14/2009] [Indexed: 11/10/2022]
Abstract
The smu.412c gene encodes a putative histidine triad-like protein (SMU.412c) with 139 residues that is involved in cell-cycle regulation in Streptococcus mutans. The gene was cloned into the expression vector pET28a and subsequently expressed in Escherichia coli strain BL21 (DE3) to give a substantially soluble form of SMU.412c with a His(6) tag at its N-terminus. The recombinant protein was purified to homogeneity in a two-step procedure involving Ni(2+)-chelating and size-exclusion chromatography. Crystals suitable for X-ray diffraction were obtained using the sitting-drop vapour-diffusion method and diffracted to 1.8 A resolution on beamline BL6A at Photon Factory, Tsukuba, Japan. The crystal belonged to space group P4(1)2(1)2, with unit-cell parameters a = b = 53.5, c = 141.1 A.
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Affiliation(s)
- Zhao-Yang Ye
- Peking University Shenzhen Graduate School, Shenzhen 518055, People’s Republic of China
- National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Qiao-Ming Hou
- Peking University Shenzhen Graduate School, Shenzhen 518055, People’s Republic of China
- National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Lan-Fen Li
- Peking University Shenzhen Graduate School, Shenzhen 518055, People’s Republic of China
| | - Xiao-Dong Su
- Peking University Shenzhen Graduate School, Shenzhen 518055, People’s Republic of China
- National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, People’s Republic of China
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El-Khamisy SF, Katyal S, Patel P, Ju L, McKinnon PJ, Caldecott KW. Synergistic decrease of DNA single-strand break repair rates in mouse neural cells lacking both Tdp1 and aprataxin. DNA Repair (Amst) 2009; 8:760-6. [PMID: 19303373 PMCID: PMC2693503 DOI: 10.1016/j.dnarep.2009.02.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 02/06/2009] [Accepted: 02/06/2009] [Indexed: 11/16/2022]
Abstract
Ataxia oculomotor apraxia-1 (AOA1) is an autosomal recessive neurodegenerative disease that results from mutations of aprataxin (APTX). APTX associates with the DNA single- and double-strand break repair machinery and is able to remove AMP from 5'-termini at DNA strand breaks in vitro. However, attempts to establish a DNA strand break repair defect in APTX-defective cells have proved conflicting and unclear. We reasoned that this may reflect that DNA strand breaks with 5'-AMP represent only a minor subset of breaks induced in cells, and/or the availability of alternative mechanisms for removing AMP from 5'-termini. Here, we have attempted to increase the dependency of chromosomal single- and double-strand break repair on aprataxin activity by slowing the rate of repair of 3'-termini in aprataxin-defective neural cells, thereby increasing the likelihood that the 5'-termini at such breaks become adenylated and/or block alternative repair mechanisms. To do this, we generated a mouse model in which APTX is deleted together with tyrosyl DNA phosphodiesterase (TDP1), an enzyme that repairs 3'-termini at a subset of single-strand breaks (SSBs), including those with 3'-topoisomerase-1 (Top1) peptide. Notably, the global rate of repair of oxidative and alkylation-induced SSBs was significantly slower in Tdp1(-/-)/Aptx(-/-) double knockout quiescent mouse astrocytes compared with Tdp1(-/-) or Aptx(-/-) single knockouts. In contrast, camptothecin-induced Top1-SSBs accumulated to similar levels in Tdp1(-/-) and Tdp1(-/-)/Aptx(-/-) double knockout astrocytes. Finally, we failed to identify a measurable defect in double-strand break repair in Tdp1(-/-), Aptx(-/-) or Tdp1(-/-)/Aptx(-/-) astrocytes. These data provide direct evidence for a requirement for aprataxin during chromosomal single-strand break repair in primary neural cells lacking Tdp1.
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Affiliation(s)
- Sherif F El-Khamisy
- Genome Damage and Stability Centre, University of Sussex, Brighton, BN1 9RQ, UK.
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Defective DNA ligation during short-patch single-strand break repair in ataxia oculomotor apraxia 1. Mol Cell Biol 2008; 29:1354-62. [PMID: 19103743 DOI: 10.1128/mcb.01471-08] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ataxia oculomotor apraxia 1 (AOA1) results from mutations in aprataxin, a component of DNA strand break repair that removes AMP from 5' termini. Despite this, global rates of chromosomal strand break repair are normal in a variety of AOA1 and other aprataxin-defective cells. Here we show that short-patch single-strand break repair (SSBR) in AOA1 cell extracts bypasses the point of aprataxin action at oxidative breaks and stalls at the final step of DNA ligation, resulting in the accumulation of adenylated DNA nicks. Strikingly, this defect results from insufficient levels of nonadenylated DNA ligase, and short-patch SSBR can be restored in AOA1 extracts, independently of aprataxin, by the addition of recombinant DNA ligase. Since adenylated nicks are substrates for long-patch SSBR, we reasoned that this pathway might in part explain the apparent absence of a chromosomal SSBR defect in aprataxin-defective cells. Indeed, whereas chemical inhibition of long-patch repair did not affect SSBR rates in wild-type mouse neural astrocytes, it uncovered a significant defect in Aptx(-/-) neural astrocytes. These data demonstrate that aprataxin participates in chromosomal SSBR in vivo and suggest that short-patch SSBR arrests in AOA1 because of insufficient nonadenylated DNA ligase.
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39
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Rass U, Ahel I, West SC. Molecular mechanism of DNA deadenylation by the neurological disease protein aprataxin. J Biol Chem 2008; 283:33994-4001. [PMID: 18836178 DOI: 10.1074/jbc.m807124200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The human neurological disease known as ataxia with oculomotor apraxia 1 is caused by mutations in the APTX gene that encodes Aprataxin (APTX) protein. APTX is a member of the histidine triad superfamily of nucleotide hydrolases and transferases but is distinct from other family members in that it acts upon DNA. The target of APTX is 5'-adenylates at DNA nicks or breaks that result from abortive DNA ligation reactions. In this work, we show that APTX acts as a nick sensor, which provides a mechanism to assess the adenylation status of unsealed nicks. When an adenylated nick is encountered by APTX, base pairing at the 5' terminus of the nick is disrupted as the adenylate is accepted into the active site of the enzyme. Adenylate removal occurs by a two-step process that proceeds through a transient AMP-APTX covalent intermediate. These results pinpoint APTX as the first protein to adopt canonical histidine triad-type reaction chemistry for the repair of DNA.
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Affiliation(s)
- Ulrich Rass
- London Research Institute, Clare Hall Laboratories, Cancer Research UK, South Mimms, Herts EN6 3LD, United Kingdom
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40
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Abstract
Hereditary defects in the repair of DNA damage are implicated in a variety of diseases, many of which are typified by neurological dysfunction and/or increased genetic instability and cancer. Of the different types of DNA damage that arise in cells, single-strand breaks (SSBs) are the most common, arising at a frequency of tens of thousands per cell per day from direct attack by intracellular metabolites and from spontaneous DNA decay. Here, the molecular mechanisms and organization of the DNA-repair pathways that remove SSBs are reviewed and the connection between defects in these pathways and hereditary neurodegenerative disease are discussed.
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Affiliation(s)
- Keith W Caldecott
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
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41
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Barzilai A, Biton S, Shiloh Y. The role of the DNA damage response in neuronal development, organization and maintenance. DNA Repair (Amst) 2008; 7:1010-27. [DOI: 10.1016/j.dnarep.2008.03.005] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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42
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Lavin MF, Gueven N, Grattan-Smith P. Defective responses to DNA single- and double-strand breaks in spinocerebellar ataxia. DNA Repair (Amst) 2008; 7:1061-76. [PMID: 18467193 DOI: 10.1016/j.dnarep.2008.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Failure to maintain the integrity of DNA/chromatin can result in genome instability and an increased risk of cancer. The description of a number of human genetic disorders characterised not only by cancer predisposition but by a broader phenotype including neurodegeneration suggests that maintaining genome stability is also important for preserving post-mitotic neurons. The identification of genes associated with other neurodegenerative disorders provides further evidence for the importance of DNA damage response and DNA repair genes in protecting against neurodegeneration. This theme is further developed in this review.
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Affiliation(s)
- Martin F Lavin
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia.
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Kulkarni A, Wilson DM. The involvement of DNA-damage and -repair defects in neurological dysfunction. Am J Hum Genet 2008; 82:539-66. [PMID: 18319069 PMCID: PMC2427185 DOI: 10.1016/j.ajhg.2008.01.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 12/17/2007] [Accepted: 01/03/2008] [Indexed: 10/22/2022] Open
Abstract
A genetic link between defects in DNA repair and neurological abnormalities has been well established through studies of inherited disorders such as ataxia telangiectasia and xeroderma pigmentosum. In this review, we present a comprehensive summary of the major types of DNA damage, the molecular pathways that function in their repair, and the connection between defective DNA-repair responses and specific neurological disease. Particular attention is given to describing the nature of the repair defect and its relationship to the manifestation of the associated neurological dysfunction. Finally, the review touches upon the role of oxidative stress, a leading precursor to DNA damage, in the development of certain neurodegenerative pathologies, such as Alzheimer's and Parkinson's.
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Affiliation(s)
- Avanti Kulkarni
- Laboratory of Molecular Gerontology, National Institute of Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - David M. Wilson
- Laboratory of Molecular Gerontology, National Institute of Aging, National Institutes of Health, Baltimore, MD 21224, USA
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Kumar M, Jayaram H, Vasquez-Del Carpio R, Jiang X, Taraporewala ZF, Jacobson RH, Patton JT, Prasad BVV. Crystallographic and biochemical analysis of rotavirus NSP2 with nucleotides reveals a nucleoside diphosphate kinase-like activity. J Virol 2007; 81:12272-84. [PMID: 17804496 PMCID: PMC2168982 DOI: 10.1128/jvi.00984-07] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rotavirus, the major pathogen of infantile gastroenteritis, carries a nonstructural protein, NSP2, essential for viroplasm formation and genome replication/packaging. In addition to RNA-binding and helix-destabilizing properties, NSP2 exhibits nucleoside triphosphatase activity. A conserved histidine (H225) functions as the catalytic residue for this enzymatic activity, and mutation of this residue abrogates genomic double-stranded RNA synthesis without affecting viroplasm formation. To understand the structural basis of the phosphatase activity of NSP2, we performed crystallographic analyses of native NSP2 and a functionally defective H225A mutant in the presence of nucleotides. These studies showed that nucleotides bind inside a cleft between the two domains of NSP2 in a region that exhibits structural similarity to ubiquitous cellular HIT (histidine triad) proteins. Only minor conformational alterations were observed in the cleft upon nucleotide binding and hydrolysis. This hydrolysis involved the formation of a stable phosphohistidine intermediate. These observations, reminiscent of cellular nucleoside diphosphate (NDP) kinases, prompted us to investigate whether NSP2 exhibits phosphoryl-transfer activity. Bioluminometric assay showed that NSP2 exhibits an NDP kinase-like activity that transfers the bound phosphate to NDPs. However, NSP2 is distinct from the highly conserved cellular NDP kinases in both its structure and catalytic mechanism, thus making NSP2 a potential target for antiviral drug design. With structural similarities to HIT proteins, which are not known to exhibit NDP kinase activity, NSP2 represents a unique example among structure-activity relationships. The newly observed phosphoryl-transfer activity of NSP2 may be utilized for homeostasis of nucleotide pools in viroplasms during genome replication.
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Affiliation(s)
- Mukesh Kumar
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Abstract
Defects in cellular DNA repair processes have been linked to genome instability, heritable cancers, and premature aging syndromes. Yet defects in some repair processes manifest themselves primarily in neuronal tissues. This review focuses on studies defining the molecular defects associated with several human neurological disorders, particularly ataxia with oculomotor apraxia 1 (AOA1) and spinocerebellar ataxia with axonal neuropathy 1 (SCAN1). A picture is emerging to suggest that brain cells, due to their nonproliferative nature, may be particularly prone to the progressive accumulation of unrepaired DNA lesions.
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Affiliation(s)
- Ulrich Rass
- London Research Institute, Cancer Research UK, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, UK
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46
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Chou TF, Cheng J, Tikh IB, Wagner CR. Evidence that human histidine triad nucleotide binding protein 3 (Hint3) is a distinct branch of the histidine triad (HIT) superfamily. J Mol Biol 2007; 373:978-89. [PMID: 17870088 DOI: 10.1016/j.jmb.2007.08.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 08/03/2007] [Accepted: 08/10/2007] [Indexed: 10/22/2022]
Abstract
Human Hint3 (hHint3) has been classified as a member of the histidine triad nucleotide (Hint) binding protein subfamily. While Hint1 is ubiquitously expressed by both eukaryotes and prokaryotes, Hint3 is found only in eukaryotes. Previously, our laboratory has characterized and compared the aminoacyl-adenylate and nucleoside phosphoramidate hydrolase activity of hHint1 and Escherichia coli hinT. In this study, hHint3-1(Ala36) and its single nucleotide polymorphism, hHint3-2 (A36G variant), were cloned, overexpressed, and purified. Steady-state kinetic studies with a synthetic fluorogenic indolepropinoic acyl-adenylate (AIPA) and with a series of fluorogenic tryptamine nucleoside phosphoramidates revealed that hHint3-1 and hHint3-2 are adenylate and phosphoramidate hydrolases with apparent second-order rate constants (kcat/Km) ranging from 10(2) to 10(6) s(-1) M(-1). Unlike hHint1, hHint3-1 and hHint3-2 prefer AIPA over tryptamine adenosine phosphoramidate by factors of 33- and 16-fold, respectively. In general, hHint3s hydrolyze phosphoramidate 370- to 2000-fold less efficiently than hHint1. Substitution of the potential active-site nucleophile, His145, by Ala was shown to abolish the adenylate and phosphoramidate hydrolase activity for hHint3-1. However, 0.2-0.4% residual activity was observed for the H145A mutant of hHint3-2. Both hHint3-1 and hHint3-2 were found to hydrolyze lysyl-adenylate generated by human lysyl-tRNA synthetase (hLysRS) by proceeding through an adenylated protein intermediate. hLysRS-dependent labeling of hHint3-1 and hHint3-2 was found to depend on His145, which aligns with the His112 of the Hint1 active site. The extent of active-site His145-AMP labeling was shown to be similar to His112-AMP labeling of hHint1. In contrast to all previously characterized members of the histidine triad superfamily, which have been shown to exist exclusively as homodimers, wild type and the H145A of hHint3-1 were found to exist across a range of multimeric states, from dimers to octamers and even larger oligomers, while wild type and the H145A of hHint3-2 exist predominantly in a monomeric state. The differences in oligomeric state may be important in vivo, because unlike tetracysteine-tagged Hint1, which was found along linear arrays exclusively in the cytoplasm in transfected HeLa cells, tagged Hint3-1 and Hint3-2 were found as aggregates both in the cytosol and in the nucleus. Taken together, these results imply that while Hint3 and Hint1 prefer aminoacyl-adenylates as substrates and catalytically interact with aminoacyl-tRNA synthetases, the significant differences in phosphoramidase activity, oligomeric state, and cellular localization suggest that Hint3s should be placed in a distinct branch of the histidine triad superfamily.
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Affiliation(s)
- Tsui-Fen Chou
- Department of Medicinal Chemistry, University of Minnesota, 8-174 Weaver Densford Hall, 308 Harvard St. S.E., Minneapolis, MN 55455, USA
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Sharma RA, Dianov GL. Targeting base excision repair to improve cancer therapies. Mol Aspects Med 2007; 28:345-74. [PMID: 17706275 DOI: 10.1016/j.mam.2007.06.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 05/30/2007] [Accepted: 06/05/2007] [Indexed: 01/05/2023]
Abstract
Most commonly used cancer therapies, particularly ionizing radiation and certain classes of cytotoxic chemotherapies, cause cell death by damaging DNA. Base excision repair (BER) is the major system responsible for the removal of corrupt DNA bases and repair of DNA single strand breaks generated spontaneously and induced by exogenous DNA damaging factors such as certain cancer therapies. In this review, the physico-chemical properties of the proteins involved in BER are discussed with particular emphasis on molecular mechanisms coordinating repair processes. The aim of this review is to apply extensive knowledge that currently exists regarding the biochemical mechanisms involved in human BER to the molecular biology of current therapies for cancer. It is anticipated that the application of this knowledge will translate into the development of novel effective therapies for improving existing treatments such as radiation therapy and oxaliplatin chemotherapy.
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Affiliation(s)
- Ricky A Sharma
- Radiation Oncology & Biology, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
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Takahashi T, Tada M, Igarashi S, Koyama A, Date H, Yokoseki A, Shiga A, Yoshida Y, Tsuji S, Nishizawa M, Onodera O. Aprataxin, causative gene product for EAOH/AOA1, repairs DNA single-strand breaks with damaged 3'-phosphate and 3'-phosphoglycolate ends. Nucleic Acids Res 2007; 35:3797-809. [PMID: 17519253 PMCID: PMC1920238 DOI: 10.1093/nar/gkm158] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Aprataxin is the causative gene product for early-onset ataxia with ocular motor apraxia and hypoalbuminemia/ataxia with oculomotor apraxia type 1 (EAOH/AOA1), the clinical symptoms of which are predominantly neurological. Although aprataxin has been suggested to be related to DNA single-strand break repair (SSBR), the physiological function of aprataxin remains to be elucidated. DNA single-strand breaks (SSBs) continually produced by endogenous reactive oxygen species or exogenous genotoxic agents, typically possess damaged 3′-ends including 3′-phosphate, 3′-phosphoglycolate, or 3′-α, β-unsaturated aldehyde ends. These damaged 3′-ends should be restored to 3′-hydroxyl ends for subsequent repair processes. Here we demonstrate by in vitro assay that recombinant human aprataxin specifically removes 3′-phosphoglycolate and 3′-phosphate ends at DNA 3′-ends, but not 3′-α, β-unsaturated aldehyde ends, and can act with DNA polymerase β and DNA ligase III to repair SSBs with these damaged 3′-ends. Furthermore, disease-associated mutant forms of aprataxin lack this removal activity. The findings indicate that aprataxin has an important role in SSBR, that is, it removes blocking molecules from 3′-ends, and that the accumulation of unrepaired SSBs with damaged 3′-ends underlies the pathogenesis of EAOH/AOA1. The findings will provide new insight into the mechanism underlying degeneration and DNA repair in neurons.
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Affiliation(s)
- Tetsuya Takahashi
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Masayoshi Tada
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Shuichi Igarashi
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Akihide Koyama
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Hidetoshi Date
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Akio Yokoseki
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Atsushi Shiga
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Yutaka Yoshida
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Shoji Tsuji
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Masatoyo Nishizawa
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Osamu Onodera
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
- *To whom correspondence should be addressed. 81 25 227 066581 25 223 6646
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Hirano M, Asai H, Kiriyama T, Furiya Y, Iwamoto T, Nishiwaki T, Yamamoto A, Mori T, Ueno S. Short half-lives of ataxia-associated aprataxin proteins in neuronal cells. Neurosci Lett 2007; 419:184-7. [PMID: 17485165 DOI: 10.1016/j.neulet.2007.04.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 04/17/2007] [Accepted: 04/22/2007] [Indexed: 11/28/2022]
Abstract
Early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH)/ataxia with oculomotor apraxia type 1 (AOA1) is caused by mutations in the gene encoding aprataxin (APTX). Although several in vitro findings proposed that impaired enzymatic activities of APTX are responsible for EAOH/AOA1, potential instability of mutant proteins has also been suggested as the pathogenesis based on in vivo finding that mutant proteins are almost undetectable in EAOH/AOA1 tissues or cells. The present study aimed to experimentally prove instability of mutant proteins in neuronal cells, the cell type preferentially affected by this disease. Results of pulse-chase experiments demonstrated that all of the disease-associated mutants had extremely shorter half-lives than the WT. We further found that mutants were targeted for rapid proteasome-mediated degradation. These results help establish pathogenic and physiological protein characteristics of APTX in neuronal cells.
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Affiliation(s)
- Makito Hirano
- Department of Neurology, Nara Medical University, Kashihara, Nara, Japan.
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Gueven N, Chen P, Nakamura J, Becherel OJ, Kijas AW, Grattan-Smith P, Lavin MF. A subgroup of spinocerebellar ataxias defective in DNA damage responses. Neuroscience 2007; 145:1418-25. [PMID: 17224243 DOI: 10.1016/j.neuroscience.2006.12.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 12/06/2006] [Accepted: 12/07/2006] [Indexed: 01/16/2023]
Abstract
A subgroup of human autosomal recessive ataxias is also characterized by disturbances of eye movement or oculomotor apraxia. These include ataxia telangiectasia (A-T); ataxia telangiectasia like disorder (ATLD); ataxia oculomotor apraxia type 1 (AOA1) and ataxia oculomotor apraxia type 2 (AOA2). What appears to be emerging is that all of these have in common some form of defect in DNA damage response which could account for the neurodegenerative changes seen in these disorders. We describe here sensitivity to DNA damaging agents in AOA1 and evidence that these cells have a defect in single strand break repair. Comparison is made with what appears to be a novel form of AOA (AOA3) which also shows sensitivity to agents that lead to single strand breaks in DNA as well as a reduced capacity to repair these breaks. AOA3 cells are defective in the DNA damage-induced p53 response. This defect can be overcome by incubation with the mdm2 antagonists, nutlins, but combined treatment with nutlins and DNA damage does not enhance the response. We also show that AOA3 cells are deficient in p73 activation after DNA damage. These data provide further evidence that different forms of AOA have in common a reduced capacity to cope with damage to DNA, which may account for the neurodegeneration observed in these syndromes.
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Affiliation(s)
- N Gueven
- Queensland Institute of Medical Research, Brisbane, QLD 4029, Australia
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