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Watson WP, Munter T, Golding BT. The effect of vitamin B 12 on DNA adduction by styrene oxide, a genotoxic xenobiotic. Chem Biol Interact 2023; 382:110591. [PMID: 37302460 DOI: 10.1016/j.cbi.2023.110591] [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: 04/13/2023] [Revised: 05/25/2023] [Accepted: 05/31/2023] [Indexed: 06/13/2023]
Abstract
Vitamin B12 (cyano- or hydroxo-cobalamin) acts, via its coenzymes, methyl- and adenosyl-cobalamin, as a partner for enzymatic reactions in humans catalysed by methionine synthase and methylmalonyl-CoA mutase. As well as its association with pernicious anaemia, human B12 deficiency may also be a risk factor for neurological illnesses, heart disease and cancer. In the present work the effect of vitamin B12 (hydroxocobalamin) on the formation of DNA adducts by the epoxide phenyloxirane (styrene oxide), a genotoxic metabolite of phenylethene (styrene), has been studied using an in vitro model system. Styrene was converted to its major metabolite styrene oxide as a mixture of enantiomers using a microsomal fraction from the livers of Sprague-Dawley rats with concomitant inhibition of epoxide hydrolase. However, microsomal oxidation of styrene in the presence of vitamin B12 gave diastereoisomeric 2-hydroxy-2-phenylcobalamins. The quantitative formation of styrene oxide-DNA adducts was investigated using 2-deoxyguanosine or calf thymus DNA in the presence or absence of vitamin B12. Microsomal incubations containing either deoxyguanosine or DNA in the absence of vitamin B12 gave 2-amino-7-(2-hydroxy-1-phenylethyl)-1,7-dihydro-6H-purin-6-one [N7-(2-hydroxy-1-phenylethyl)-guanine], and 2-amino-7-(2-hydroxy-2-phenylethyl)-1,7-dihydro-6H-purin-6-one [N7-(2-hydroxy-2-phenylethyl)guanine] as the principal adducts. With deoxyguanosine the level of formation of guanine adducts was ca. 150 adducts/106 unmodified nucleoside. With DNA the adduct level was 36 pmol/mg DNA (ca. 1 adduct/0.83 × 105 nucleotides). Styrene oxide adducts from deoxyguanosine or DNA were not detected in microsomal incubations of styrene in the presence of vitamin B12. These results suggest that vitamin B12 could protect DNA against genotoxicity due to styrene oxide and other xenobiotic metabolites. However, this potential defence mechanism requires that the 2-hydroxyalkylcobalamins derived from epoxides are not 'anti-vitamins' and ideally liberate, and therefore, recycle vitamin B12. Otherwise, depletion of vitamin B12 leading to human deficiency could increase the risk of carcinogenesis initiated by genotoxic epoxides.
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Affiliation(s)
- William P Watson
- Syngenta Central Toxicology Laboratory, Alderley Park, Cheshire, SK10 4TJ, UK
| | - Tony Munter
- Syngenta Central Toxicology Laboratory, Alderley Park, Cheshire, SK10 4TJ, UK
| | - Bernard T Golding
- School of Natural and Environmental Sciences - Chemistry, Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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2
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Black E, Rasch A, Wimmer T, Li A, Araujo A, Cieslak S, Steed KS, Adhikari RD, Wisco JJ, Hutchinson BA. The effects of age, genotype and diet on hippocampal subfield iron dysregulation and Alzheimer's disease biomarkers in an ApoE mouse model. Eur J Neurosci 2023; 57:1033-1047. [PMID: 36775930 DOI: 10.1111/ejn.15933] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 01/05/2023] [Accepted: 02/02/2023] [Indexed: 02/14/2023]
Abstract
Current theories regarding accumulation of Alzheimer's disease-related deposits of abnormal intra- and extracellular proteins include reactions to inflammation and mitochondrial dysfunction. In this study, we explored whether age, genotype and inflammation via diet have a greater effect on dysregulatory protein accumulation in any particular subfield of the hippocampus. We stained for ferritin, ferroportin, hyperphosphorylated tau and β-amyloid proteins in the hippocampal region of Apolipoprotein E2 (ApoE2), ApoE3 or ApoE4 mice fed a control diet or a hypothesized inflammation-inducing methionine diet and euthanized at 3, 6, 9 or 12 months. We analysed stains based on hippocampal subfield and compared the protein accumulation levels within each group. We found significantly decreased ferritin expression in ApoE4 mice in the CA1 and Hi regions and decreased ferroportin expression in ApoE4 mice in the Hi region. There was also a significant effect on hyperphosphorylated tau protein levels based upon a given mouse genotype and diet interaction. Additionally, there were nonsignificant trends in each hippocampal subfield of increasing ferroportin and hyperphosphorylated tau after 6 months of age and decreasing β-amyloid and ferritin with age. This study identified that there are changes in iron regulatory molecules based on genotype in the Hi and CA1 regions. Our findings also suggest a diet-genotype interaction, which affects levels of specific Alzheimer's disease biomarkers in the hippocampus. Additionally, we identified a trend toward increased ability to clear β-amyloid and decreased ability to clear hyperphosphorylated tau with age in all subfields, in addition to evidence of increasing iron load with time.
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Affiliation(s)
- Elisabeth Black
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah, USA.,Georgetown University School of Medicine, Washington, District of Columbia, USA
| | - Abbey Rasch
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah, USA.,Department of Anatomy and Neurobiology, Boston University Aram V. Chobanian & Edward Avedisian School of Medicine, Boston, Massachusetts, USA
| | - Tyler Wimmer
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah, USA
| | - Alivia Li
- Department of Anatomy and Neurobiology, Boston University Aram V. Chobanian & Edward Avedisian School of Medicine, Boston, Massachusetts, USA
| | - Amanda Araujo
- Department of Anatomy and Neurobiology, Boston University Aram V. Chobanian & Edward Avedisian School of Medicine, Boston, Massachusetts, USA
| | - Steve Cieslak
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah, USA.,Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, USA
| | - Kevin S Steed
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah, USA.,California Health Sciences University, College of Osteopathic Medicine, Clovis, California, USA
| | - Rajan D Adhikari
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah, USA.,Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jonathan J Wisco
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah, USA.,Department of Anatomy and Neurobiology, Boston University Aram V. Chobanian & Edward Avedisian School of Medicine, Boston, Massachusetts, USA
| | - Bre Anna Hutchinson
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah, USA
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Smith AD, Refsum H, Bottiglieri T, Fenech M, Hooshmand B, McCaddon A, Miller JW, Rosenberg IH, Obeid R. Homocysteine and Dementia: An International Consensus Statement. J Alzheimers Dis 2019; 62:561-570. [PMID: 29480200 PMCID: PMC5836397 DOI: 10.3233/jad-171042] [Citation(s) in RCA: 191] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Identification of modifiable risk factors provides a crucial approach to the prevention of dementia. Nutritional or nutrient-dependent risk factors are especially important because dietary modifications or use of dietary supplements may lower the risk factor level. One such risk factor is a raised concentration of the biomarker plasma total homocysteine, which reflects the functional status of three B vitamins (folate, vitamins B12, B6). A group of experts reviewed literature evidence from the last 20 years. We here present a Consensus Statement, based on the Bradford Hill criteria, and conclude that elevated plasma total homocysteine is a modifiable risk factor for development of cognitive decline, dementia, and Alzheimer’s disease in older persons. In a variety of clinical studies, the relative risk of dementia in elderly people for moderately raised homocysteine (within the normal range) ranges from 1.15 to 2.5, and the Population Attributable risk ranges from 4.3 to 31%. Intervention trials in elderly with cognitive impairment show that homocysteine-lowering treatment with B vitamins markedly slows the rate of whole and regional brain atrophy and also slows cognitive decline. The findings are consistent with moderately raised plasma total homocysteine (>11 μmol/L), which is common in the elderly, being one of the causes of age-related cognitive decline and dementia. Thus, the public health significance of raised tHcy in the elderly should not be underestimated, since it is easy, inexpensive, and safe to treat with B vitamins. Further trials are needed to see whether B vitamin treatment will slow, or prevent, conversion to dementia in people at risk of cognitive decline or dementia.
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Affiliation(s)
- A David Smith
- OPTIMA, Department of Pharmacology, University of Oxford, Oxford, UK
| | - Helga Refsum
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Teodoro Bottiglieri
- Center of Metabolomics, Institute of Metabolic Disease, Baylor Scott & White Research Institute, Dallas, TX, USA
| | - Michael Fenech
- Genome Health and Personalised Nutrition Laboratory, CSIRO Health and Biosecurity, Adelaide BC, SA, Australia
| | - Babak Hooshmand
- Aging Research Centre, Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden
| | - Andrew McCaddon
- Cardiff University, School of Medicine, Gwenfro Units 6/7, Wrexham, UK
| | - Joshua W Miller
- Department of Nutritional Sciences, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
| | - Irwin H Rosenberg
- Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Rima Obeid
- Department of Clinical Chemistry and Laboratory Medicine, University Hospital of the Saarland, Germany
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McCaddon A, Miller JW. Assessing the association between homocysteine and cognition: reflections on Bradford Hill, meta-analyses, and causality. Nutr Rev 2015; 73:723-35. [DOI: 10.1093/nutrit/nuv022] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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McCaddon A. Vitamin B12 in neurology and ageing; clinical and genetic aspects. Biochimie 2012; 95:1066-76. [PMID: 23228515 DOI: 10.1016/j.biochi.2012.11.017] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 11/27/2012] [Indexed: 01/13/2023]
Abstract
The classic neurological and psychiatric features associated with vitamin B12 deficiency have been well described and are the subject of many excellent review articles. The advent of sensitive diagnostic tests, including homocysteine and methylmalonic acid assays, has revealed a surprisingly high prevalence of a more subtle 'subclinical' form of B12 deficiency, particularly within the elderly. This is often associated with cognitive impairment and dementia, including Alzheimer's disease. Metabolic evidence of B12 deficiency is also reported in association with other neurodegenerative disorders including vascular dementia, Parkinson's disease and multiple sclerosis. These conditions are all associated with chronic neuro-inflammation and oxidative stress. It is possible that these clinical associations reflect compromised vitamin B12 metabolism due to such stress. Physicians are also increasingly aware of considerable inter-individual variation in the clinical response to B12 replacement therapy. Further research is needed to determine to what extent this is attributable to genetic determinants of vitamin B12 absorption, distribution and cellular uptake.
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Affiliation(s)
- Andrew McCaddon
- School of Medicine, Cardiff University, Gwenfro Units 6/7, Wrexham Technology Park, Wrexham LL17 7YP, Wales, United Kingdom.
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Prakash J, Kodanko JJ. Synthesis, Characterization, and Glutathionylation of Cobalamin Model Complexes [Co(N4PyCO2Me)Cl]Cl2 and [Co(Bn-CDPy3)Cl]Cl2. Inorg Chem 2012; 51:2689-98. [DOI: 10.1021/ic2026736] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jai Prakash
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit,
Michigan 48202, United States
| | - Jeremy J. Kodanko
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit,
Michigan 48202, United States
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Birch CS, Brasch NE, McCaddon A, Williams JHH. A novel role for vitamin B(12): Cobalamins are intracellular antioxidants in vitro. Free Radic Biol Med 2009; 47:184-8. [PMID: 19409980 DOI: 10.1016/j.freeradbiomed.2009.04.023] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 04/14/2009] [Accepted: 04/22/2009] [Indexed: 01/29/2023]
Abstract
Oxidative stress is a feature of many chronic inflammatory diseases. Such diseases are associated with up-regulation of a vitamin B(12) (cobalamin) blood transport protein and its membrane receptor, suggesting a link between cobalamin and the cellular response to inflammation. The ability of cobalamin to regulate inflammatory cytokines suggests that it may have antioxidative properties. Here we show that cobalamins, including the novel thiolatocobalamins N-acetyl-l-cysteinylcobalamin and glutathionylcobalamin, are remarkably effective antioxidants in vitro. We also show that thiolatocobalamins have superior efficacy compared with other cobalamin forms, other cobalamins in combination with N-acetyl-l-cysteine (NAC) or glutathione (GSH), and NAC or GSH alone. Pretreatment of Sk-Hep-1 cells with thiolatocobalamins afforded robust protection (>90% cell survival) against exposure to 30 microM concentrations of the pro-oxidants homocysteine and hydrogen peroxide. The compounds inhibited intracellular peroxide production, maintained intracellular glutathione levels, and prevented apoptotic and necrotic cell death. Moreover, thiolatocobalamins are remarkably nontoxic in vitro at supraphysiological concentrations (>2 mM). Our results demonstrate that thiolatocobalamins act as powerful but benign antioxidants at pharmacological concentrations. Because inflammatory oxidative stress is a component of many conditions, including atherosclerosis, dementia, and trauma, their utility in treating such disorders merits further investigation.
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Affiliation(s)
- Catherine S Birch
- Chester Centre for Stress Research, University of Chester, Parkgate Road, Chester CH1 4BJ, UK
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