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Jemth AS, Gustafsson R, Bräutigam L, Henriksson L, Vallin KSA, Sarno A, Almlöf I, Homan E, Rasti A, Warpman Berglund U, Stenmark P, Helleday T. MutT homologue 1 (MTH1) catalyzes the hydrolysis of mutagenic O6-methyl-dGTP. Nucleic Acids Res 2019; 46:10888-10904. [PMID: 30304478 PMCID: PMC6237811 DOI: 10.1093/nar/gky896] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 09/21/2018] [Indexed: 12/15/2022] Open
Abstract
Nucleotides in the free pool are more susceptible to nonenzymatic methylation than those protected in the DNA double helix. Methylated nucleotides like O6-methyl-dGTP can be mutagenic and toxic if incorporated into DNA. Removal of methylated nucleotides from the nucleotide pool may therefore be important to maintain genome integrity. We show that MutT homologue 1 (MTH1) efficiently catalyzes the hydrolysis of O6-methyl-dGTP with a catalytic efficiency similar to that for 8-oxo-dGTP. O6-methyl-dGTP activity is exclusive to MTH1 among human NUDIX proteins and conserved through evolution but not found in bacterial MutT. We present a high resolution crystal structure of human and zebrafish MTH1 in complex with O6-methyl-dGMP. By microinjecting fertilized zebrafish eggs with O6-methyl-dGTP and inhibiting MTH1 we demonstrate that survival is dependent on active MTH1 in vivo. O6-methyl-dG levels are higher in DNA extracted from zebrafish embryos microinjected with O6-methyl-dGTP and inhibition of O6-methylguanine-DNA methyl transferase (MGMT) increases the toxicity of O6-methyl-dGTP demonstrating that O6-methyl-dGTP is incorporated into DNA. MTH1 deficiency sensitizes human cells to the alkylating agent Temozolomide, a sensitization that is more pronounced upon MGMT inhibition. These results expand the cellular MTH1 function and suggests MTH1 also is important for removal of methylated nucleotides from the nucleotide pool.
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Affiliation(s)
- Ann-Sofie Jemth
- Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Robert Gustafsson
- Department of Biochemistry and Biophysics, Stockholm University, S-106 91 Stockholm, Sweden
| | - Lars Bräutigam
- Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Linda Henriksson
- Department of Biochemistry and Biophysics, Stockholm University, S-106 91 Stockholm, Sweden
| | - Karl S A Vallin
- Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Antonio Sarno
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.,Department of Pathology, St. Olavs Hospital, Trondheim, Norway
| | - Ingrid Almlöf
- Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Evert Homan
- Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Azita Rasti
- Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Ulrika Warpman Berglund
- Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, S-106 91 Stockholm, Sweden
| | - Thomas Helleday
- Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden.,Sheffield Cancer Centre, Department of Oncology and Metabolism, University of Sheffield, Sheffield S10 2RX, UK
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Machado AMD, Figueiredo C, Seruca R, Rasmussen LJ. Helicobacter pylori infection generates genetic instability in gastric cells. Biochim Biophys Acta Rev Cancer 2010; 1806:58-65. [PMID: 20122996 DOI: 10.1016/j.bbcan.2010.01.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 01/16/2010] [Accepted: 01/24/2010] [Indexed: 01/02/2023]
Abstract
The discovery that Helicobacter pylori is associated with gastric cancer has led to numerous studies that investigate the mechanisms by which H. pylori induces carcinogenesis. Gastric cancer shows genetic instability both in nuclear and mitochondrial DNA, besides impairment of important DNA repair pathways. As such, this review highlights the consequences of H. pylori infection on the integrity of DNA in the host cells. By down-regulating major DNA repair pathways, H. pylori infection has the potential to generate mutations. In addition, H. pylori infection can induce direct changes on the DNA of the host, such as oxidative damage, methylation, chromosomal instability, microsatellite instability, and mutations. Interestingly, H. pylori infection generates genetic instability in nuclear and mitochondrial DNA. Based on the reviewed literature we conclude that H. pylori infection promotes gastric carcinogenesis by at least three different mechanisms: (1) a combination of increased endogenous DNA damage and decreased repair activities, (2) induction of mutations in the mitochondrial DNA, and (3) generation of a transient mutator phenotype that induces mutations in the nuclear genome.
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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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Golankiewicz B, Januszczyk P, Zeidler J, Popenda M. An efficient route to novel 4,5-di- and 2,4,5-tri substituted imidazoles from imidazo[1,5-a]-1,3,5-triazine (5,8-diaza-7,9-dideazapurine) derivatives. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2004; 23:127-36. [PMID: 15043141 DOI: 10.1081/ncn-120027822] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Two new types of imidazole derivatives: N-(2-R1-5-R2-1H-imidazol-4-yl) thioureas 7a-g and N-(2-R1-5-R2-1H-imidazol-4-yl) formamides 8b,c,g were obtained in high yields by the hydrolytic degradation of 6-R1-8-R2-2-thioxo-2,3-dihydroimidazo[1,5-a]-1,3,5-triazin-4(1H)-ones 5a-g and 6-R1-8-R2-imidazo[1,5-a]-1,3,5-triazin-4(3H)-ones 6b,c,d, respectively. The tautomeric preferences of the new imidazoles were determined.
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Mudipalli A, Maccubbin AE, Nadadur SS, Struck RF, Gurtoo HL. Mutations induced by monofunctional and bifunctional phosphoramide mustards in supF tRNA gene. Mutat Res 1997; 381:49-57. [PMID: 9403030 DOI: 10.1016/s0027-5107(97)00147-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The relative mutagenicity, nature of the mutations and the sequence specificity of mutations induced by the bifunctional alkylating agent, phosphoramide mustard (PM) and a monofunctional derivative, dechloroethyl phosphoramide mustard (dePM), were analyzed by the Ames test and by an in vitro shuttle vector mutagenesis assay. Both PM and dePM increased the mutation frequency above background in either assay. However, on an equimolar basis, dePM was less mutagenic than PM. In the in vitro shuttle vector mutagenesis assay, sequencing demonstrated that about 40% of the mutant plasmids contained more than one mutation in the supF tRNA gene segment of the plasmid. About 70% of the mutations observed in dePM-treated plasmids were single base substitutions with A:T and G:C base pairs being mutated at equivalent rates. In contrast, only about 50% of the mutations observed in PM-treated plasmids were single base substitutions, 80% of which involved G:C base pairs. Single base deletions and insertions were found in approximately equal proportions with both compounds; however, these lesions were in greater abundance in PM-treated plasmids. Putative hot-spots for mutation in the supF tRNA gene included base pairs at position 102 and 110 for PM and positions 170 and 171 for dePM.
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Affiliation(s)
- A Mudipalli
- Department of Experimental Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263-0001, USA
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