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Levy MA, Tian J, Gandelman M, Cheng H, Tsapekos M, Crego SR, Maddela R, Sinnott R. A Multivitamin Mixture Protects against Oxidative Stress-Mediated Telomere Shortening. J Diet Suppl 2023; 21:53-70. [PMID: 36847305 DOI: 10.1080/19390211.2023.2179153] [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] [Indexed: 03/01/2023]
Abstract
Telomeres are nucleotide repeat sequences located at the end of chromosomes that protect them from degradation and maintain chromosomal stability. Telomeres shorten with each cell division; hence telomere length is associated with aging and longevity. Numerous lifestyle factors have been identified that impact the rate of telomere shortening; high vitamin consumption has been associated with longer telomere length, whereas oxidative stress is associated with telomere shortening. In this paper, we sought to determine if a multivitamin mixture containing both vitamins and a blend of polyphenolic compounds, could reduce telomere shortening consequent to an oxidative stress (10 uM H2O2 for 8 weeks) in a primary fibroblast cell culture model. Under conditions of oxidative stress, the median and 20th percentile telomere length were significantly greater (p < 0.05), and the percentage of critically short telomeres (<3000 bp) was significantly less (p < 0.05) in cells treated with the multivitamin mixture at 4, 15 and 60 ug/ml compared to control (0 ug/ml). Median and 20th percentile telomere shortening rate was also reduced under the same conditions (p < 0.05). Taken together, these findings demonstrate that the multivitamin mixture protects against oxidative stress-mediated telomere shortening in cell culture, findings which may have implications in human health.
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Affiliation(s)
- Mark A Levy
- Department of Research and Development, USANA Health Science, Inc., Salt Lake City, Utah, USA
| | - Junqiang Tian
- Department of Research and Development, USANA Health Science, Inc., Salt Lake City, Utah, USA
| | - Mandi Gandelman
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Haojie Cheng
- Department of Research and Development, USANA Health Science, Inc., Salt Lake City, Utah, USA
| | | | | | - Rolando Maddela
- Department of Research and Development, USANA Health Science, Inc., Salt Lake City, Utah, USA
| | - Robert Sinnott
- Department of Research and Development, USANA Health Science, Inc., Salt Lake City, Utah, USA
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Robert G, Wagner JR, Cadet J. Oxidatively generated tandem DNA modifications by pyrimidinyl and 2-deoxyribosyl peroxyl radicals. Free Radic Biol Med 2023; 196:22-36. [PMID: 36603668 DOI: 10.1016/j.freeradbiomed.2022.12.104] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/27/2022] [Accepted: 12/30/2022] [Indexed: 01/03/2023]
Abstract
Molecular oxygen sensitizes DNA to damage induced by ionizing radiation, Fenton-like reactions, and other free radical-mediated reactions. It rapidly converts carbon-centered radicals within DNA into peroxyl radicals, giving rise to a plethora of oxidized products consisting of nucleobase and 2-deoxyribose modifications, strand breaks and abasic sites. The mechanism of formation of single oxidation products has been extensively studied and reviewed. However, much evidence shows that reactive peroxyl radicals can propagate damage to vicinal components in DNA strands. These intramolecular reactions lead to the dual alteration of two adjacent nucleotides, designated as tandem or double lesions. Herein, current knowledge about the formation and biological implications of oxidatively generated DNA tandem lesions is reviewed. Thus far, most reported tandem lesions have been shown to arise from peroxyl radicals initially generated at pyrimidine bases, notably thymine, followed by reaction with 5'-flanking bases, especially guanine, although contiguous thymine lesions have also been characterized. Proper biomolecular processing is impaired by several tandem lesions making them refractory to base excision repair and potentially more mutagenic.
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Affiliation(s)
- Gabriel Robert
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - J Richard Wagner
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, Québec, J1H 5N4, Canada.
| | - Jean Cadet
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, Québec, J1H 5N4, Canada.
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Zheng L, Greenberg MM. Traceless Tandem Lesion Formation in DNA from a Nitrogen-Centered Purine Radical. J Am Chem Soc 2018; 140:6400-6407. [PMID: 29738242 DOI: 10.1021/jacs.8b02828] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nitrogen-centered nucleoside radicals are commonly produced reactive intermediates in DNA exposed to γ-radiolysis and oxidants, but their reactivity is not well understood. Examination of the reactivity of independently generated 2'-deoxyadenosin- N6-yl radical (dA•) reveals that it is an initiator of tandem lesions, an important form of DNA damage that is a hallmark of γ-radiolysis. dA• yields O2-dependent tandem lesions by abstracting a hydrogen atom from the C5-methyl group of a 5'-adjacent thymidine to form 5-(2'-deoxyuridinyl)methyl radical (T•). The subsequently formed thymidine peroxyl radical adds to the 5'-adjacent dG, ultimately producing a 5'-OxodGuo-fdU tandem lesion. Importantly, the initial hydrogen abstraction repairs dA• to form dA. Thus, the involvement of dA• in tandem lesion formation is traceless by product analysis. The tandem lesion structure, as well as the proposed mechanism, are supported by LC-MS/MS, isotopic labeling, chemical reactivity experiments, and independent generation of T•. Tandem lesion formation efficiency is dependent on the ease of ionization of the 5'-flanking sequence, and the yields are >27% in the 5'-d(GGGT) flanking sequence. The traceless involvement of dA• in tandem lesion formation may be general for nitrogen-centered radicals in nucleic acids, and presents a new pathway for forming a deleterious form of DNA damage.
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Affiliation(s)
- Liwei Zheng
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Marc M Greenberg
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
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Paul R, Greenberg MM. Mechanistic Studies on RNA Strand Scission from a C2'-Radical. J Org Chem 2016; 81:9199-9205. [PMID: 27668445 DOI: 10.1021/acs.joc.6b01760] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The C2'-carbon-hydrogen bond in ribonucleotides is significantly weaker than other carbohydrate carbon-hydrogen bonds in RNA or DNA. Independent generation of the C2'-uridine radical (1) in RNA oligonucleotides via Norrish type I photocleavage of a ketone-substituted nucleotide yields direct strand breaks via cleavage of the β-phosphate. The reactivity of 1 in different sequences and under a variety of conditions suggests that the rate constant for strand scission is significantly greater than 106 s-1 at pH 7.2. The initially formed C2'-radical (1) is not trapped under a variety of conditions, consistent with computational studies ( Chem.-Eur. J. 2009 , 15 , 2394 ) that suggest that the barrier to strand scission is very low and that synchronous proton transfer from the 2'-hydroxyl to the departing phosphate group facilitates cleavage. The C2'-radical could be a significant contributor to RNA strand scission by the hydroxyl radical, particularly under anaerobic conditions where 1 can be produced from nucleobase radicals.
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Affiliation(s)
- Rakesh Paul
- Department of Chemistry, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Marc M Greenberg
- Department of Chemistry, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
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Greenberg MM. Reactivity of Nucleic Acid Radicals. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2016; 50:119-202. [PMID: 28529390 DOI: 10.1016/bs.apoc.2016.02.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Nucleic acid oxidation plays a vital role in the etiology and treatment of diseases, as well as aging. Reagents that oxidize nucleic acids are also useful probes of the biopolymers' structure and folding. Radiation scientists have contributed greatly to our understanding of nucleic acid oxidation using a variety of techniques. During the past two decades organic chemists have applied the tools of synthetic and mechanistic chemistry to independently generate and study the reactive intermediates produced by ionizing radiation and other nucleic acid damaging agents. This approach has facilitated resolving mechanistic controversies and lead to the discovery of new reactive processes.
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Lartia R, Constant JF. Synthetic access to the chemical diversity of DNA and RNA 5′-aldehyde lesions. J Org Chem 2015; 80:705-10. [PMID: 25372153 DOI: 10.1021/jo502170e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydrogen atom abstraction from the C5′-position of nucleotides in DNA results in direct strand scission by generating alkali-labile fragments from the oxidized nucleotide. The major damage consists in a terminus containing a 5′-aldehyde as part of an otherwise undamaged nucleotide. Moreover it is considered as a polymorphic DNA strand break lesion since it can be borne by any of the four nucleosides encountered in DNA. Here we propose an expeditious synthesis of oligonucleotides (ON) ending with this 5′-aldehyde group (5′-AODN). This straightforward and cheap strategy relies on Pfitzner–Moffatt oxidation performed on solid support followed by a transient protection of the resulting aldehyde function. This method is irrespective of the 5′-terminal nucleobase and most interestingly can be directly extended to RNA to produce the corresponding 5′-AORN. We also report preliminary results on recognition of 5′-AODN by base excision repair (BER) enzymes.
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Fotouhi A, Cornella N, Ramezani M, Wojcik A, Haghdoost S. Investigation of micronucleus induction in MTH1 knockdown cells exposed to UVA, UVB or UVC. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 793:161-5. [PMID: 26520386 DOI: 10.1016/j.mrgentox.2015.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 06/03/2015] [Indexed: 11/17/2022]
Abstract
The longer wave parts of UVR can increase the production of reactive oxygen species (ROS) which can oxidize nucleotides in the DNA or in the nucleotide pool leading to mutations. Oxidized bases in the DNA are repaired mainly by the DNA base excision repair system and incorporation of oxidized nucleotides into newly synthesized DNA can be prevented by the enzyme MTH1. Here we hypothesize that the formation of several oxidized base damages (from pool and DNA) in close proximity, would cause a high number of base excision repair events, leading to DNA double strand breaks (DSB) and therefore giving rise to cytogenetic damage. If this hypothesis is true, cells with low levels of MTH1 will show higher cytogenetic damage after the longer wave parts of UVR. We analyzed micronuclei induction (MN) as an endpoint for cytogenetic damage in the human lymphoblastoid cell line, TK6, with a normal and a reduced level of MTH1 exposed to UVR. The results indicate a higher level of micronuclei at all incubation times after exposure to the longer wave parts of UVR. There is no significant difference between wildtype and MTH1-knockdown TK6 cells, indicating that MTH1 has no protective role in UVR-induced cytogenetic damage. This indicates that DSBs induced by UV arise from damage forms by direct interaction of UV or ROS with the DNA rather than through oxidation of dNTP.
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Affiliation(s)
- Asal Fotouhi
- Center for Radiation Protection Research, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Sweden
| | - Nicola Cornella
- Center for Radiation Protection Research, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Sweden
| | - Mehrafarin Ramezani
- Center for Radiation Protection Research, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Sweden
| | - Andrzej Wojcik
- Center for Radiation Protection Research, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Sweden
| | - Siamak Haghdoost
- Center for Radiation Protection Research, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Sweden.
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Abstract
The uridin-2'-yl radical (1) has been proposed as an intermediate during RNA oxidation. However, its reactivity has not been thoroughly studied due to the complex conditions under which it is typically generated. The uridin-2'-yl radical was independently generated from a benzyl ketone (2a) via Norrish type I photocleavage upon irradiation at λmax = 350 nm. Dioxygen and β-mercaptoethanol are unable to compete with loss of uracil from 1 in phosphate buffer. Thiol trapping competes with uracil fragmentation in less polar solvent conditions. This is ascribed mostly to a reduction in the rate constant for uracil elimination in the less polar solvent. Hydrogen atom transfer to 1 from β-mercaptoethanol occurs exclusively from the α-face to produce arabinouridine. Mass balances range from 72 to 95%. Furthermore, the synthesis of 2a is amenable to formation of the requisite phosphoramidite for solid-phase oligonucleotide synthesis. This and the fidelity with which the urdin-2'-yl radical is generated from 2a suggest that this precursor should be useful for studying the radical's reactivity in synthetic oligonucleotides.
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Affiliation(s)
- Rakesh Paul
- Department of Chemistry, Johns
Hopkins University 3400
North Charles Street, Baltimore, Maryland 21218, United
States
| | - Marc M. Greenberg
- Department of Chemistry, Johns
Hopkins University 3400
North Charles Street, Baltimore, Maryland 21218, United
States
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Amato NJ, Bryant-Friedrich AC. The impact of structure on oxidatively generated DNA damage products resulting from the C3'-thymidinyl radical. Chembiochem 2012; 14:187-90. [PMID: 23280951 DOI: 10.1002/cbic.201200723] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Indexed: 11/05/2022]
Abstract
What's the damage? Trapping the C3'-thymidinyl radical in biologically significant architectures delivers both the repaired oligomer and 1-(2'-deoxy-β-D-threo-pentofuranosyl)thymidine-containing substrates. The stereoselectivity of the reduction was found to be dependent upon the DNA structure.
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Affiliation(s)
- Nicholas J Amato
- Department of Chemistry, The University of Toledo, 2801 W. Bancroft St., Toledo, OH 43606-3390, USA
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