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Xu Y, Shui X, Gao M, Zhang Y, Zhang Z, Zhu Z, Zhao B, Sun D. Toxicological effects and mechanisms of lithium on growth, photosynthesis and antioxidant system in the freshwater microalga Chromochloris zofingiensis. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:133898. [PMID: 38422737 DOI: 10.1016/j.jhazmat.2024.133898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/02/2024] [Accepted: 02/24/2024] [Indexed: 03/02/2024]
Abstract
The growing prevalence of lithium (Li) batteries has drawn public attention to Li as an emerging pollutant. The present study investigates the toxicity of Li+ on Chromochloris zofingiensis, examining physiological, biochemical and omics aspects. Results reveal hormesis effects of Li+ on C. zofingiensis growth. At Li+ concentrations below 5 mg L-1, Li+ can enhance chlorophyll content, mitochondrial activity, and antioxidant capacity, leading to increased dry cell weight and cell number. Conversely, when it exceeded 10 mg L-1, Li+ can reduce chlorophyll content, induce oxidative stress, and disrupt chloroplast and mitochondria structure and function, ultimately impeding cell growth. In addition, under 50 mg L-1 Li+ stress, microalgae optimize absorbed light energy use (increasing Fv/Fm and E TR ) and respond to stress by up-regulating genes in starch and lipid biosynthesis pathways, promoting the accumulation of storage components. Weighted gene co-expression network analysis indicates that peptidylprolyl cis/trans isomerase, GTPase and L-ascorbate oxidase might be the key regulators in response to Li+ stress. This research marks the toxic effects and molecular mechanisms of Li+ on freshwater microalga, which would improve our understanding of Li's toxicology and contributing to the establishment of Li pollution standards.
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Affiliation(s)
- Yaqi Xu
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaborative Innovation Center for Eco-Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Xiaoxi Shui
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaborative Innovation Center for Eco-Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Min Gao
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaborative Innovation Center for Eco-Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Yushu Zhang
- School of Life Sciences, Hebei University, Baoding 071000, China
| | - Zhao Zhang
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaborative Innovation Center for Eco-Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Zhengge Zhu
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaborative Innovation Center for Eco-Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Baohua Zhao
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaborative Innovation Center for Eco-Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Dongzhe Sun
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaborative Innovation Center for Eco-Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
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2
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Oguro A, Fujiyama T, Ishihara Y, Kataoka C, Yamamoto M, Eto K, Komohara Y, Imaoka S, Sakuragi T, Tsuji M, Shibata E, Kotake Y, Yamazaki T. Maternal DHA intake in mice increased DHA metabolites in the pup brain and ameliorated MeHg-induced behavioral disorder. J Lipid Res 2023; 64:100458. [PMID: 37838304 PMCID: PMC10656226 DOI: 10.1016/j.jlr.2023.100458] [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: 02/17/2023] [Revised: 10/05/2023] [Accepted: 10/07/2023] [Indexed: 10/16/2023] Open
Abstract
Although pregnant women's fish consumption is beneficial for the brain development of the fetus due to the DHA in fish, seafood also contains methylmercury (MeHg), which adversely affects fetal brain development. Epidemiological studies suggest that high DHA levels in pregnant women's sera may protect the fetal brain from MeHg-induced neurotoxicity, but the underlying mechanism is unknown. Our earlier study revealed that DHA and its metabolite 19,20-dihydroxydocosapentaenoic acid (19,20-DHDP) produced by cytochrome P450s (P450s) and soluble epoxide hydrolase (sEH) can suppress MeHg-induced cytotoxicity in mouse primary neuronal cells. In the present study, DHA supplementation to pregnant mice suppressed MeHg-induced impairments of pups' body weight, grip strength, motor function, and short-term memory. DHA supplementation also suppressed MeHg-induced oxidative stress and the decrease in the number of subplate neurons in the cerebral cortex of the pups. DHA supplementation to dams significantly increased the DHA metabolites 19,20-epoxydocosapentaenoic acid (19,20-EDP) and 19,20-DHDP as well as DHA itself in the fetal and infant brains, although the expression levels of P450s and sEH were low in the fetal brain and liver. DHA metabolites were detected in the mouse breast milk and in human umbilical cord blood, indicating the active transfer of DHA metabolites from dams to pups. These results demonstrate that DHA supplementation increased DHA and its metabolites in the mouse pup brain and alleviated the effects of MeHg on fetal brain development. Pregnant women's intake of fish containing high levels of DHA (or DHA supplementation) may help prevent MeHg-induced neurotoxicity in the fetus.
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Affiliation(s)
- Ami Oguro
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
| | - Taichi Fujiyama
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yasuhiro Ishihara
- Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | | | | | - Komyo Eto
- National Institute for Minamata Disease, Kumamoto, Japan
| | - Yoshihiro Komohara
- Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Susumu Imaoka
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, Hyogo, Japan
| | - Toshihide Sakuragi
- Department of Environmental Health, School of Medicine, University of Occupational and Environmental Health, Fukuoka, Japan; Department of Obstetrics and Gynecology, School of Medicine, University of Occupational and Environmental Health, Fukuoka, Japan
| | - Mayumi Tsuji
- Department of Environmental Health, School of Medicine, University of Occupational and Environmental Health, Fukuoka, Japan
| | - Eiji Shibata
- Department of Obstetrics and Gynecology, Dokkyo Medical University, Tochigi, Japan
| | - Yaichiro Kotake
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Takeshi Yamazaki
- Program of Life and Environmental Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
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3
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Rupa SA, Patwary MAM, Matin MM, Ghann WE, Uddin J, Kazi M. Interaction of mercury species with proteins: towards possible mechanism of mercurial toxicology. Toxicol Res (Camb) 2023; 12:355-368. [PMID: 37397928 PMCID: PMC10311172 DOI: 10.1093/toxres/tfad039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 05/02/2023] [Accepted: 05/15/2023] [Indexed: 07/04/2023] Open
Abstract
The nature of the binding of mercurials (organic and inorganic) and their subsequent transformations in biological systems is a matter of great debate as several different hypotheses have been proposed and none of them has been conclusively proven to explain the characteristics of Hg binding with the proteins. Thus, the chemical nature of Hg-protein binding through the possible transportation mechanism in living tissues is critically reviewed herein. Emphasis is given to the process of transportation, and binding of Hg species with selenol-containing biomolecules that are appealing for toxicological studies as well as the advancement of environmental and biological research.
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Affiliation(s)
| | | | | | - William Emmanuel Ghann
- Center for Nanotechnology, Department of Natural Sciences, Coppin State University, Baltimore, MD 21216, USA
| | - Jamal Uddin
- Center for Nanotechnology, Department of Natural Sciences, Coppin State University, Baltimore, MD 21216, USA
| | - Mohsin Kazi
- Department of Pharmaceutics, College of Pharmacy, King Saud University, P.O. BOX-2457, Riyadh 11451, Saudi Arabia
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Ye Y, Chen Y, Wu H, Fu Y, Sun Y, Wang X, Li P, Wu Z, Wang J, Yang Z, Zhou E. Investigations into ferroptosis in methylmercury-induced acute kidney injury in mice. ENVIRONMENTAL TOXICOLOGY 2023; 38:1372-1383. [PMID: 36880449 DOI: 10.1002/tox.23770] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 02/10/2023] [Accepted: 02/20/2023] [Indexed: 05/18/2023]
Abstract
Methylmercury (MeHg) is a highly poisonous form of mercury and a risk factor for kidney impairment in humans that currently has no effective means of therapy. Ferroptosis is a non-apoptotic metabolic cell death linked to numerous diseases. It is currently unknown whether ferroptosis takes part in MeHg-induced kidney damage. Here, we established a model of acute kidney injury (AKI) in mice by gavage with different doses of MeHg (0, 40, 80, 160 μmol/kg). Serological analysis revealed elevated levels of UA, UREA, and CREA; H&E staining showed variable degrees of renal tubule injury; qRT-PCR detection displayed increased expression of KIM-1 and NGAL in the groups with MeHg treatment, indicated that MeHg successfully induced AKI. Furthermore, MDA levels enhanced in renal tissues of mice with MeHg exposure whereas GSH levels decreased; ACSL4 and PTGS2 nucleic acid levels elevated while SLC7A11 levels reduced; transmission electron microscopy illustrated that the density of the mitochondrial membrane thickened and the ridge reduced considerably; protein levels for 4HNE and TfR1 improved since GPX4 levels declined, all these results implying the involvement of ferroptosis as a result of MeHg exposure. Additionally, the observed elevation in the protein levels of NLRP3, p-p65, p-p38, p-ERK1/2, and KEAP1 in tandem with downregulated Nrf2 expression levels indicate the involvement of the NF-κB/NLRP3/MAPK/Nrf2 pathways. All the above findings suggested that ferroptosis and the NF-κB/NLRP3/MAPK/Nrf2 pathways are implicated in MeHg-induced AKI, thereby providing a theoretical foundation and reference for future investigations into the prevention and treatment of MeHg-induced kidney injury.
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Affiliation(s)
- Yingrong Ye
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Yichun Chen
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Hanpeng Wu
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Yiwu Fu
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Youpeng Sun
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Xia Wang
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Peixuan Li
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Zhikai Wu
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Jingjing Wang
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Zhengtao Yang
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
| | - Ershun Zhou
- College of Life Sciences and Engineering, Foshan University, Foshan, Guangdong Province, People's Republic of China
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Horai S, Abiko Y, Unoki T, Shinkai Y, Akiyama M, Nakata K, Kunisue T, Kumagai Y. Concentrations of nucleophilic sulfur species in small Indian mongoose (Herpestes auropunctatus) in Okinawa, Japan. CHEMOSPHERE 2022; 295:133833. [PMID: 35120952 DOI: 10.1016/j.chemosphere.2022.133833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/27/2022] [Accepted: 01/31/2022] [Indexed: 06/14/2023]
Abstract
Reactive sulfur species (RSS), such as hydrogen per (poly)sulfide, cysteine per (poly)sulfide, glutathione per (poly)sulfide, and protein-bound per (poly)sulfides, can easily react with environmental electrophiles such as methylmercury (MeHg), because of their high nucleophilicity. These RSS are produced by enzymes such as cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) and are found in mammalian organs. Organs of wildlife have not been analyzed for hydrogen sulfide, cysteine, glutathione, and RSS. In this study, low molecular weight nucleophilic sulfur substances, including RSS, were quantified by stable isotope dilution assay-based liquid chromatography-mass spectrometry using β-(4-hydroxyphenyl)ethyl iodoacetamide to capture the target chemicals in the small Indian mongoose which species possesses high mercury content as same as some marine mammals. Western blotting revealed that the mongoose organs (liver, kidney, cerebrum, and cerebellum) contained proteins that cross-reacted with anti-CBS and CSE antibodies. The expression patterns of these enzymes were similar to those in mice, indicating that mongoose organs contain CBS and CSE. Moreover, bis-methylmercury sulfide (MeHg)2S, which is a low toxic compound in comparison to MeHg, was found in the liver of this species. These results suggest that the small Indian mongoose produces RSS and monothiols associated with detoxification of electrophilic organomercury. The animals which have high mercury content in their bodies may have function of mercury detoxification involved not only Se but also RSS interactions.
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Affiliation(s)
- Sawako Horai
- Environmental Health Section, Department of Environment and Public Health, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan.
| | - Yumi Abiko
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
| | - Takamitsu Unoki
- Hygienic Chemistry Section, Department of Basic Medical Sciences, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan.
| | - Yasuhiro Shinkai
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
| | - Masahiro Akiyama
- Research Center for Drug Discovery, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University, 1-5-30 Shibakoen, Minato-ku, Tokyo, 105-8512, Japan.
| | - Katsushi Nakata
- Nansei Environmental Laboratory Co., Ltd., 4-4 Agarizaki, Nishihara, Okinawa, 903-0105, Japan.
| | - Tatsuya Kunisue
- Center for Marine Environmental Studies, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, 790-8577, Japan.
| | - Yoshito Kumagai
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
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Unoki T, Akiyama M, Shinkai Y, Kumagai Y, Fujimura M. Spatio-temporal distribution of reactive sulfur species during methylmercury exposure in the rat brain. J Toxicol Sci 2022; 47:31-37. [PMID: 34987139 DOI: 10.2131/jts.47.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Brain susceptibility to methylmercury (MeHg) is developmentally and regionally specific in both humans and rodents, but the mechanism is not well clarified. Reactive sulfur species (RSS) with high nucleophilicity can react with MeHg, leading to the formation of a less toxic metabolite bismethylmercury sulfide, thus exerting cytoprotection. In this study, we assessed the variation of RSS content in the rat brain and evaluated its relevance in sensitivity to MeHg. Analyses of fetal/juvenile rat brains showed low RSS levels in early developmental stages. Site-specific analysis of adult rat brains revealed that cerebellar RSS levels were lower than those of the hippocampus. Microscopically, RSS levels of the granular cell layer were lower than those of the molecular layer in the cerebellum. Thus, low RSS levels corresponded with age and site of the brain that is vulnerable to MeHg. Taken together with the finding that brain RSS were consumed during MeHg exposure, these results indicate that RSS is a factor that defines the specificity of MeHg vulnerability in the brain.
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Affiliation(s)
- Takamitsu Unoki
- Department of Basic Medical Sciences, National Institute for Minamata Disease
| | - Masahiro Akiyama
- Research Center for Drug Discovery, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University
| | - Yasuhiro Shinkai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba
| | - Masatake Fujimura
- Department of Basic Medical Sciences, National Institute for Minamata Disease
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7
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Nishimura A, Tanaka T, Kato Y, Nishiyama K, Nishida M. Cardiac robustness regulated by reactive sulfur species. J Clin Biochem Nutr 2022; 70:1-6. [PMID: 35068674 PMCID: PMC8764107 DOI: 10.3164/jcbn.21-84] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 08/17/2021] [Indexed: 11/22/2022] Open
Abstract
The human myocardium contains robust cells that constantly beat from birth to death without being replaced, even when exposed to various environmental stresses. Myocardial robustness is thought to depend primarily on the strength of the reducing power to protect the heart from oxidative stress. Myocardial antioxidant systems are controlled by redox reactions, primarily via the redox reaction of Cys sulfhydryl groups, such as found in thioredoxin and glutathione. However, the specific molecular entities that regulate myocardial reducing power have long been debated. Recently, reactive sulfide species, with excellent electron transfer ability, consisting of a series of multiple sulfur atoms, i.e., Cys persulfide and Cys polysulfides, have been found to play an essential role in maintaining mitochondrial quality and function, as well as myocardial robustness. This review presents the latest findings on the molecular mechanisms underlying mitochondrial energy metabolism and the maintenance of quality control by reactive sulfide species and provides a new insight for the prevention of chronic heart failure.
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Affiliation(s)
- Akiyuki Nishimura
- National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences
| | - Tomohiro Tanaka
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences
| | - Yuri Kato
- Department of Physiology, Graduate School of Pharmaceutical Sciences, Kyushu University
| | - Kazuhiro Nishiyama
- Department of Physiology, Graduate School of Pharmaceutical Sciences, Kyushu University
| | - Motohiro Nishida
- National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences
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8
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Comparative Study of Cytotoxicity, DNA Damage and Oxidative Stress Induced by Heavy Metals Cd(II), Hg(II) and Cr(III) in Yeast. Curr Microbiol 2021; 78:1856-1863. [PMID: 33770215 DOI: 10.1007/s00284-021-02454-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 03/10/2021] [Indexed: 01/09/2023]
Abstract
Wide range of applications of heavy metals and improperly discarded their castoffs possess serious threats to environment and human health. In this study, cytotoxicity, DNA damage and oxidative stress induced by Cd(II), Hg(II) and Cr(III) were comparatively studied in yeast Saccharomyces cerevisiae. Cd(II), Hg(II), and Cr(III) all produced strong cytotoxicity resulting in growth inhibition and cell mortality to varying degrees (Hg(II) > Cd(II) > Cr(III)). Hg(II) produced more oxidative stress. Cr(III) caused more serious DNA damage in vitro. Cd(II) also caused both obvious DNA damage and oxidative stress at higher concentration, but not as efficiently as Cd(II) and Hg(II). A further null mutation sensitivity assay showed that the relative sensitivity of rad1∆ to the metals was Cr(III) > Cd(II) > Hg(II), and that of trx1∆ to the metals was Hg(II) > Cd(II) > Cr(III). These data provide a clear evidence that the Cr(III) can cause significant DNA damage and potential genotoxicity; Hg(II) can strongly inhibit SOD activity, produce lipid peroxidation and cause serious membrane injury, suggesting these heavy metals can cause different toxic effects in different ways.
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9
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Huang L, Fang Z, Gao J, Wang J, Li Y, Sun L, Wang Y, Liao J, Gooneratne R. Protective role of l-threonine against cadmium toxicity in Saccharomyces cerevisiae. J Basic Microbiol 2021; 61:339-350. [PMID: 33570201 DOI: 10.1002/jobm.202100012] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 01/28/2021] [Accepted: 02/02/2021] [Indexed: 12/11/2022]
Abstract
Environment and food contamination with cadmium (Cd) can cause serious toxicity, posing a severe threat to agricultural production and human health. However, how amino acids contribute to defenses against oxidative stress caused by Cd in cells is not fully understood. As a model eukaryote with a relatively clear genetic background, Saccharomyces cerevisiae has been commonly used in Cd toxicity research. To gain insight into Cd toxicity and cell defenses against it, 20 amino acids were screened for protective roles against Cd stress in S. cerevisiae. The results showed that threonine (Thr, T) had the strongest protective effect against Cd-induced mortality and membrane damage in the cells. Compared to the antioxidant vitamin C (VC), Thr exhibited a higher efficacy in restoring the superoxide dismutase (SOD) activity that was inhibited by Cd but not by H2 O2 in vivo. Thr exhibited evident DPPH (2,2-diphenyl-1-picrylhydrazyl) activity but weak ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-9 sulfonic acid)) scavenging activity, giving it a weaker effect against Cd-induced lipid peroxidation and superoxide radical O2- , compared to VC. More importantly, compared to the chelating agent EDTA, Thr showed stronger chelation of Cd, giving it a stronger protective effect on SOD against Cd than VC in vitro. The results of the in vivo and in vitro experiments revealed that the role Thr plays in cell defenses against Cd may be attributed to its protection of the SOD enzyme, predominantly through the preferential chelation of Cd. Our results provide insights into the protective mechanisms of amino acid Thr that ameliorate Cd toxicity and suggest that a supplement of Thr might help to reduce Cd-induced oxidative damage.
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Affiliation(s)
- Linru Huang
- College of Food Science and Technology, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology, Research Center of Marine Food, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Cunjin College, Guangdong Ocean University, Zhanjiang, China
| | - Zhijia Fang
- College of Food Science and Technology, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology, Research Center of Marine Food, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Cunjin College, Guangdong Ocean University, Zhanjiang, China
| | - Jian Gao
- College of Food Science and Technology, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology, Research Center of Marine Food, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Cunjin College, Guangdong Ocean University, Zhanjiang, China
| | - Jingwen Wang
- College of Food Science and Technology, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology, Research Center of Marine Food, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Cunjin College, Guangdong Ocean University, Zhanjiang, China
| | - Yongbin Li
- College of Food Science and Technology, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology, Research Center of Marine Food, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Cunjin College, Guangdong Ocean University, Zhanjiang, China
| | - Lijun Sun
- College of Food Science and Technology, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology, Research Center of Marine Food, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Cunjin College, Guangdong Ocean University, Zhanjiang, China
| | - Yaling Wang
- College of Food Science and Technology, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology, Research Center of Marine Food, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Cunjin College, Guangdong Ocean University, Zhanjiang, China
| | - Jianmeng Liao
- Institute for Food and Drug Control, Zhanjiang, China
| | - Ravi Gooneratne
- Department of Wine, Food, and Molecular Biosciences, Lincoln University, Lincoln, Canterbury, New Zealand
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10
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Seki N, Akiyama M, Yamakawa H, Hase K, Kumagai Y, Kim YG. Adverse effects of methylmercury on gut bacteria and accelerated accumulation of mercury in organs due to disruption of gut microbiota. J Toxicol Sci 2021; 46:91-97. [PMID: 33536393 DOI: 10.2131/jts.46.91] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Methylmercury (MeHg), an environmental electrophile, binds covalently to the cysteine residues of proteins in organs, altering protein function and causing cytotoxicity. MeHg has also been shown to alter the composition of gut microbes. The gut microbiota is a complex community, the disturbance of which has been linked to the development of certain diseases. However, the relationship between MeHg and gut bacteria remains poorly understood. In this study, we showed that MeHg binds covalently to gut bacterial proteins via cysteine residues. We examined the effects of MeHg on the growth of selected Lactobacillus species, namely, L. reuteri, L. gasseri, L. casei, and L. acidophilus, that are frequently either positively or negatively correlated with human diseases. The results revealed that MeHg inhibits the growth of Lactobacillus to varying degrees depending on the species. Furthermore, the growth of L. reuteri, which was inhibited by MeHg exposure, was restored by Na2S2 treatment. By comparing mice with and without gut microbiota colonization, we found that gut bacteria contribute to the production of reactive sulfur species such as hydrogen sulfide and hydrogen persulfide in the gut. We also discovered that the removal of gut bacteria accelerated accumulation of mercury in the cerebellum, liver, and lungs of mice subsequent to MeHg exposure. These results accordingly indicate that MeHg is captured and inactivated by the hydrogen sulfide and hydrogen persulfide produced by intestinal microbes, thereby providing evidence for the role played by gut microbiota in reducing MeHg toxicity.
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Affiliation(s)
- Natsumi Seki
- Research Center for Drug Discovery, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University
- Division of Biochemistry, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University
| | - Masahiro Akiyama
- Research Center for Drug Discovery, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba
| | - Hiroto Yamakawa
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba
| | - Koji Hase
- Research Center for Drug Discovery, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University
- Division of Biochemistry, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba
| | - Yun-Gi Kim
- Research Center for Drug Discovery, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University
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11
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Kasamatsu S. Persulfide-Dependent Regulation of Electrophilic Redox Signaling in Neural Cells. Antioxid Redox Signal 2020; 33:1320-1331. [PMID: 32536194 DOI: 10.1089/ars.2020.8130] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Significance: Redox homeostasis is precisely modulated by intricate systems that regulate production, elimination, and metabolism of electrophilic substances (electrophiles) in the nervous system. Since the first report of the endogenous production of reactive persulfide species in cells, such as cysteine persulfides (CysSSH), these reactive species have been a topic of extreme interest in the field of redox biology; persulfides/polysulfides possess unique chemical properties and are involved in multiple cellular functions. Recent Advances: Electrophilic signaling is mainly regulated by endogenous electrophiles that are generated from reactive oxygen species, nitric oxide, and their derivatives during stress responses, as well as by exogenous electrophiles, including compounds in foods and environmental pollutants, such as methylmercury (MeHg). Among diverse electrophiles that are endogenously generated, 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP) possesses unique redox properties, of which the biosynthetic pathway, signaling mechanism, and metabolism in cells have been elucidated. Critical Issues: Persulfides, such as CysSSH, that are endogenously produced are critically involved in 8-nitro-cGMP metabolism. Exposure of neurons to the exogenous neurotoxicant, MeHg, causes severe neurodegeneration via disruption of persulfide-dependent 8-nitro-cGMP metabolism. Future Directions: Accumulating evidence indicates that persulfides are involved in various cellular functions under physiological and pathological conditions. These new aspects of redox biology related to persulfides may be frontiers of cell research, medical and clinical investigations of neurodegenerative diseases, as well as other fields. 8-Nitro-cGMP-mediated signaling and its persulfide-dependent metabolism in cells could, therefore, be potential targets for drug development, which may lead to the discovery of new therapeutic agents for many diseases, including neurodegenerative diseases.
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Affiliation(s)
- Shingo Kasamatsu
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Osaka, Japan
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12
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Fujimura M, Usuki F. Methylmercury-Mediated Oxidative Stress and Activation of the Cellular Protective System. Antioxidants (Basel) 2020; 9:antiox9101004. [PMID: 33081221 PMCID: PMC7602710 DOI: 10.3390/antiox9101004] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/09/2020] [Accepted: 10/14/2020] [Indexed: 12/17/2022] Open
Abstract
Methylmercury (MeHg) is a well-known neurotoxicant that causes severe intoxication in humans. In Japan, it is referred to as Minamata disease, which involves two characteristic clinical forms: fetal type and adult type depending on the exposed age. In addition to MeHg burden level, individual susceptibility to MeHg plays a role in the manifestation of MeHg toxicity. Research progress has pointed out the importance of oxidative stress in the pathogenesis of MeHg toxicity. MeHg has a high affinity for selenohydryl groups, sulfhydryl groups, and selenides. It has been clarified that such affinity characteristics cause the impairment of antioxidant enzymes and proteins, resulting in the disruption of antioxidant systems. Furthermore, MeHg-induced intracellular selenium deficiency due to the greater affinity of MeHg for selenohydryl groups and selenides leads to failure in the recoding of a UGA codon for selenocysteine and results in the degradation of antioxidant selenoenzyme mRNA by nonsense-mediated mRNA decay. The defect of antioxidant selenoenzyme replenishment exacerbates MeHg-mediated oxidative stress. On the other hand, it has also been revealed that MeHg can directly activate the antioxidant Keap1/Nrf2 signaling pathway. This review summarizes the incidence of MeHg-mediated oxidative stress from the viewpoint of the individual intracellular redox system interactions and the MeHg-mediated aforementioned intracellular events. In addition, the mechanisms of cellular stress pathways and neuronal cell death triggered by MeHg-mediated oxidative stress and direct interactions of MeHg with reactive residues of proteins are mentioned.
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Affiliation(s)
- Masatake Fujimura
- Department of Basic Medical Sciences, National Institute for Minamata Disease, Kumamoto 867-0008, Japan;
| | - Fusako Usuki
- Division of Neuroimmunology, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima 890-8544, Japan
- Correspondence: ; Tel.: +81-99-275-6246; Fax: +81-99-275-5942
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Ajsuvakova OP, Tinkov AA, Aschner M, Rocha JB, Michalke B, Skalnaya MG, Skalny AV, Butnariu M, Dadar M, Sarac I, Aaseth J, Bjørklund G. Sulfhydryl groups as targets of mercury toxicity. Coord Chem Rev 2020; 417:213343. [PMID: 32905350 PMCID: PMC7470069 DOI: 10.1016/j.ccr.2020.213343] [Citation(s) in RCA: 142] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The present study addresses existing data on the affinity and conjugation of sulfhydryl (thiol; -SH) groups of low- and high-molecular-weight biological ligands with mercury (Hg). The consequences of these interactions with special emphasis on pathways of Hg toxicity are highlighted. Cysteine (Cys) is considered the primary target of Hg, and link its sensitivity with thiol groups and cellular damage. In vivo, Hg complexes play a key role in Hg metabolism. Due to the increased affinity of Hg to SH groups in Cys residues, glutathione (GSH) is reactive. The geometry of Hg(II) glutathionates is less understood than that with Cys. Both Cys and GSH Hg-conjugates are important in Hg transport. The binding of Hg to Cys mediates multiple toxic effects of Hg, especially inhibitory effects on enzymes and other proteins that contain free Cys residues. In blood plasma, albumin is the main Hg-binding (Hg2+, CH3Hg+, C2H5Hg+, C6H5Hg+) protein. At the Cys34 residue, Hg2+ binds to albumin, whereas other metals likely are bound at the N-terminal site and multi-metal binding sites. In addition to albumin, Hg binds to multiple Cys-containing enzymes (including manganese-superoxide dismutase (Mn-SOD), arginase I, sorbitol dehydrogenase, and δ-aminolevulinate dehydratase, etc.) involved in multiple processes. The affinity of Hg for thiol groups may also underlie the pathways of Hg toxicity. In particular, Hg-SH may contribute to apoptosis modulation by interfering with Akt/CREB, Keap1/Nrf2, NF-κB, and mitochondrial pathways. Mercury-induced oxidative stress may ensue from Cys-Hg binding and inhibition of Mn-SOD (Cys196), thioredoxin reductase (TrxR) (Cys497) activity, as well as limiting GSH (GS-HgCH3) and Trx (Cys32, 35, 62, 65, 73) availability. Moreover, Hg-thiol interaction also is crucial in the neurotoxicity of Hg by modulating the cytoskeleton and neuronal receptors, to name a few. However, existing data on the role of Hg-SH binding in the Hg toxicity remains poorly defined. Therefore, more research is needed to understand better the role of Hg-thiol binding in the molecular pathways of Hg toxicology and the critical role of thiols to counteract negative effects of Hg overload.
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Affiliation(s)
- Olga P. Ajsuvakova
- Yaroslavl State University, Yaroslavl, Russia
- Federal Scientific Center of Biological Systems and Agrotechnologies of the Russian Academy of Sciences, Orenburg, Russia
- IM Sechenov First Moscow State Medical University, Moscow, Russia
| | - Alexey A. Tinkov
- Yaroslavl State University, Yaroslavl, Russia
- Federal Scientific Center of Biological Systems and Agrotechnologies of the Russian Academy of Sciences, Orenburg, Russia
- IM Sechenov First Moscow State Medical University, Moscow, Russia
| | - Michael Aschner
- IM Sechenov First Moscow State Medical University, Moscow, Russia
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - João B.T. Rocha
- Departamento de Bioquímica e Biologia Molecular, CCNE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | | | | | - Anatoly V. Skalny
- Yaroslavl State University, Yaroslavl, Russia
- Federal Scientific Center of Biological Systems and Agrotechnologies of the Russian Academy of Sciences, Orenburg, Russia
- IM Sechenov First Moscow State Medical University, Moscow, Russia
| | - Monica Butnariu
- Banat’s University of Agricultural Sciences and Veterinary Medicine “King Michael I of Romania” from Timișoara, Timişoara, Romania
- CONEM Romania Biotechnology and Environmental Sciences Group, Banat’s University of Agricultural Sciences and Veterinary Medicine “King Michael I of Romania” from Timișoara, Timişoara, Romania
| | - Maryam Dadar
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - Ioan Sarac
- Banat’s University of Agricultural Sciences and Veterinary Medicine “King Michael I of Romania” from Timișoara, Timişoara, Romania
- CONEM Romania Biotechnology and Environmental Sciences Group, Banat’s University of Agricultural Sciences and Veterinary Medicine “King Michael I of Romania” from Timișoara, Timişoara, Romania
| | - Jan Aaseth
- IM Sechenov First Moscow State Medical University, Moscow, Russia
- Research Department, Innlandet Hospital Trust, Brumunddal, Norway
| | - Geir Bjørklund
- Council for Nutritional and Environmental Medicine (CONEM), Mo i Rana, Norway
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Oxidative Stress Biomarkers in Erythrocytes of Captive Pre-Juvenile Loggerhead Turtles Following Acute Exposure to Methylmercury. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10103602] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This study describes the use of erythrocytes (RBCs) of loggerhead turtles as in vitro models for evaluating their toxicity to methylmercury. Blood samples of loggerhead turtles that were born in the Colombian Caribbean were used. The LC50 of RBCs to methylmercury was determined at 96 h using methylmercury concentrations of 0.5–100 mg L−1. Next, the viability of the RBCs and the activity of the enzymes superoxide dismutase (SOD), glutathione S-transferase (GST), and lipid peroxidation by malondialdehyde (MDA) at 6 and 12 h of exposure to acute concentrations of 0, 1, and 5 mg L−1 were evaluated. The LC50 for loggerhead turtle RBCs was 8.32 mg L−1. The cell viability bioassay of RBCs exposed for 12 h only showed 100% cell viability. Increasing in vitro MeHg concentrations caused a corresponding increase in MDA concentration as well as decreases in the activities of SOD and GST. The RBCs represent an excellent model for ecotoxicological studies and SOD, GST, and MDA are biomarkers of environmental pollution and oxidative stress in loggerhead turtles. This was the first study conducted on loggerhead turtle where the response of RBCs to MeHg-induced oxidative stress is evaluated.
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Yang L, Zhang Y, Wang F, Luo Z, Guo S, Strähle U. Toxicity of mercury: Molecular evidence. CHEMOSPHERE 2020; 245:125586. [PMID: 31881386 DOI: 10.1016/j.chemosphere.2019.125586] [Citation(s) in RCA: 173] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/28/2019] [Accepted: 12/08/2019] [Indexed: 05/25/2023]
Abstract
Minamata disease in Japan and the large-scale poisoning by methylmercury (MeHg) in Iraq caused wide public concerns about the risk emanating from mercury for human health. Nowadays, it is widely known that all forms of mercury induce toxic effects in mammals, and increasing evidence supports the concern that environmentally relevant levels of MeHg could impact normal biological functions in wildlife. The information of mechanism involved in mercurial toxicity is growing but knowledge gaps still exist between the adverse effects and mechanisms of action, especially at the molecular level. A body of data obtained from experimental studies on mechanisms of mercurial toxicity in vivo and in vitro points to that disruption of the antioxidant system may play an important role in the mercurial toxic effects. Moreover, the accumulating evidence indicates that signaling transduction, protein or/and enzyme activity, and gene regulation are involving in mediating toxic and adaptive response to mercury exposure. We conducted here a comprehensive review of mercurial toxic effects on wildlife and human, in particular synthesized key findings of molecular pathways involved in mercurial toxicity from the cells to human. We discuss the molecular evidence related mercurial toxicity to the adverse effects, with particular emphasis on the gene regulation. The further studies relying on Omic analysis connected to adverse effects and modes of action of mercury will aid in the evaluation and validation of causative relationship between health outcomes and gene expression.
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Affiliation(s)
- Lixin Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China; Center for Global Health, School of Public Health, Nanjing Medical University, 211166, Nanjing, China.
| | - Yuanyuan Zhang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Feifei Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Zidie Luo
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Shaojuan Guo
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Uwe Strähle
- Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
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Nishimura A, Shimoda K, Tanaka T, Toyama T, Nishiyama K, Shinkai Y, Numaga-Tomita T, Yamazaki D, Kanda Y, Akaike T, Kumagai Y, Nishida M. Depolysulfidation of Drp1 induced by low-dose methylmercury exposure increases cardiac vulnerability to hemodynamic overload. Sci Signal 2019; 12:12/587/eaaw1920. [DOI: 10.1126/scisignal.aaw1920] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Akiyuki Nishimura
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
| | - Kakeru Shimoda
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
- SOKENDAI (School of Life Science, Graduate University for Advanced Studies), Okazaki 444-8787, Japan
| | - Tomohiro Tanaka
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
- Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
| | - Takashi Toyama
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
| | - Kazuhiro Nishiyama
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yasuhiro Shinkai
- Center for Novel Science Initiatives (CNSI), NINS, Tokyo 105-0001, Japan
| | - Takuro Numaga-Tomita
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
- SOKENDAI (School of Life Science, Graduate University for Advanced Studies), Okazaki 444-8787, Japan
| | - Daiju Yamazaki
- Division of Pharmacology, National Institute of Health Sciences, Kanagawa, 210-9501, Japan
| | - Yasunari Kanda
- Division of Pharmacology, National Institute of Health Sciences, Kanagawa, 210-9501, Japan
| | - Takaaki Akaike
- Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan
| | - Yoshito Kumagai
- Center for Novel Science Initiatives (CNSI), NINS, Tokyo 105-0001, Japan
| | - Motohiro Nishida
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
- SOKENDAI (School of Life Science, Graduate University for Advanced Studies), Okazaki 444-8787, Japan
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Kadam S, Kanitkar M, Dixit K, Deshpande R, Seshadri V, Kale V. Curcumin reverses diabetes-induced endothelial progenitor cell dysfunction by enhancing MnSOD expression and activity in vitro and in vivo. J Tissue Eng Regen Med 2018; 12:1594-1607. [DOI: 10.1002/term.2684] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 04/04/2018] [Accepted: 04/16/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Sheetal Kadam
- Stem Cell Lab; National Centre for Cell Science; Pune Maharashtra India
| | - Meghana Kanitkar
- Stem Cell Lab; National Centre for Cell Science; Pune Maharashtra India
| | - Kadambari Dixit
- Stem Cell Lab; National Centre for Cell Science; Pune Maharashtra India
| | - Rucha Deshpande
- Stem Cell Lab; National Centre for Cell Science; Pune Maharashtra India
| | | | - Vaijayanti Kale
- Stem Cell Lab; National Centre for Cell Science; Pune Maharashtra India
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Finger JW, Botero J, Zhang Y, Still SE, Hoffman AJ, Kavazis AN, Cristol DA, Wada H. No Effect of Lifelong Methylmercury Exposure on Oxidative Status in Zebra Finches (Taeniopygia guttata): A Demonstration of Methylmercury-Induced Selection? BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2017; 99:668-672. [PMID: 29080113 DOI: 10.1007/s00128-017-2202-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/25/2017] [Indexed: 06/07/2023]
Abstract
Songbirds exposed to methylmercury (MeHg) often exhibit reduced reproductive success and cognitive abilities. To better understand whether oxidative stress plays a role, we dosed zebra finches (Taeniopygia guttata) with a contaminated (1.2 ppm MeHg-cysteine) or control diet for their entire lives, including during development in the egg. Levels of antioxidant enzymes [superoxide dismutase (SOD1 and SOD2)], oxidative damage (4-hydroxynonenal; 4-HNE), and antioxidant transcription factors [nuclear factor (erythroid-derived 2)-like 2; Nrf2] were measured in the liver and pectoralis muscle of adults. MeHg treatment did not affect levels of 4-HNE or liver SOD2 or Nrf2. Birds in the MeHg treatment differed significantly from controls in pectoralis SOD1 and Nrf2, and tended to differ in liver SOD1 and pectoralis SOD2; however, we detected no overall pattern of effect of MeHg on oxidative status in dosed finches. We suspect that this is a consequence of the differential survival of MeHg-tolerant birds.
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Affiliation(s)
- John W Finger
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA.
| | - Juan Botero
- Department of Biology, College of William & Mary, Williamsburg, VA, 23185, USA
| | - Yufeng Zhang
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Shelby E Still
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Alexander J Hoffman
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
| | | | - Daniel A Cristol
- Department of Biology, College of William & Mary, Williamsburg, VA, 23185, USA
| | - Haruka Wada
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
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Fujimura M, Usuki F. In situ different antioxidative systems contribute to the site-specific methylmercury neurotoxicity in mice. Toxicology 2017; 392:55-63. [PMID: 29030019 DOI: 10.1016/j.tox.2017.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/28/2017] [Accepted: 10/06/2017] [Indexed: 01/17/2023]
Abstract
Methylmercury (MeHg), an environmental toxicant, induces site-specific neurotoxicity in adult human and animal models. In this study, we demonstrated that MeHg-induced neuropathological changes of the brain in mice were remarkable in the cerebrocortical neurons of deeper layers (dl-CCNs), but not in the CCNs of shallow layers (sl-CCNs) and the hippocampal neurons of cornu ammonis 1 (CA1-HNs). Total mercury concentration was not corresponded to the pathological changes. Here, we investigated the cause of such site-specific MeHg neurotoxicity with a focus on in situ antioxidative systems due to its critical role in MeHg intoxication. We performed in situ analyses of antioxidative enzymes expression using RT-qPCR analyses from laser microdissected sl-CCNs, dl-CCNs, and CA1-HNs samples, and immunohistochemistry. The results of antioxidative enzymes expression analyses demonstrated the lowest basal expression levels of mRNA and proteins, especially manganese superoxide dismutase (Mn-SOD) and glutathione peroxidase 1 (GPx1) in dl-CCNs. In addition, the Mn-SOD expression showed a lowest response to MeHg in dl-CCNs. We also performed enzymatic activity analyses for antioxidative enzymes using separated cerebral cortex and hippocampus. The results of enzymatic activity analyses indicate that the expression levels of antioxidative enzymes reflect their enzymatic activities. Immunostaining of thymidine glycerol, a sensitive oxidative stress marker, showed selectively increased expression in dl-CCNs after the exposure to MeHg but not in sl-CCNs and CA1-HNs, suggesting the occurrence of MeHg-induced oxidative stress in dl-CCNs. The differences in MeHg-induced occurrence of oxidative stress and pathological changes in sl-CCNs, dl-CCNs, and CA1-HNs corresponded to the basal level of Mn-SOD and GPx1 expression and the different protective response of Mn-SOD expression to MeHg. These findings suggest that the in situ different antioxidative systems play a role in the site-specific neurotoxicity of MeHg.
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Affiliation(s)
- Masatake Fujimura
- Department of Basic Medical Sciences, National Institute for Minamata Disease, Kumamoto, Japan.
| | - Fusako Usuki
- Department of Clinical Medicine, National Institute for Minamata Disease, Kumamoto, Japan
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Ihara H, Kasamatsu S, Kitamura A, Nishimura A, Tsutsuki H, Ida T, Ishizaki K, Toyama T, Yoshida E, Abdul Hamid H, Jung M, Matsunaga T, Fujii S, Sawa T, Nishida M, Kumagai Y, Akaike T. Exposure to Electrophiles Impairs Reactive Persulfide-Dependent Redox Signaling in Neuronal Cells. Chem Res Toxicol 2017; 30:1673-1684. [PMID: 28837763 DOI: 10.1021/acs.chemrestox.7b00120] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Electrophiles such as methylmercury (MeHg) affect cellular functions by covalent modification with endogenous thiols. Reactive persulfide species were recently reported to mediate antioxidant responses and redox signaling because of their strong nucleophilicity. In this study, we used MeHg as an environmental electrophile and found that exposure of cells to the exogenous electrophile elevated intracellular concentrations of the endogenous electrophilic molecule 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP), accompanied by depletion of reactive persulfide species and 8-SH-cGMP which is a metabolite of 8-nitro-cGMP. Exposure to MeHg also induced S-guanylation and activation of H-Ras followed by injury to cerebellar granule neurons. The electrophile-induced activation of redox signaling and the consequent cell damage were attenuated by pretreatment with a reactive persulfide species donor. In conclusion, exogenous electrophiles such as MeHg with strong electrophilicity impair the redox signaling regulatory mechanism, particularly of intracellular reactive persulfide species and therefore lead to cellular pathogenesis. Our results suggest that reactive persulfide species may be potential therapeutic targets for attenuating cell injury by electrophiles.
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Affiliation(s)
- Hideshi Ihara
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University , Osaka 599-8531, Japan
| | - Shingo Kasamatsu
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University , Osaka 599-8531, Japan.,Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine , Sendai 980-8575, Japan
| | - Atsushi Kitamura
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University , Osaka 599-8531, Japan
| | - Akira Nishimura
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine , Sendai 980-8575, Japan
| | - Hiroyasu Tsutsuki
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto 860-8556, Japan
| | - Tomoaki Ida
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine , Sendai 980-8575, Japan
| | - Kento Ishizaki
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University , Osaka 599-8531, Japan
| | - Takashi Toyama
- Environmental Biology Section, Faculty of Medicine, University of Tsukuba , Tsukuba, Ibaraki 305-8575, Japan
| | - Eiko Yoshida
- Environmental Biology Section, Faculty of Medicine, University of Tsukuba , Tsukuba, Ibaraki 305-8575, Japan
| | - Hisyam Abdul Hamid
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine , Sendai 980-8575, Japan.,Department of Pharmaceutical Pharmacology and Chemistry, Faculty of Pharmacy, Universiti Teknologi MARA Puncak Alam Campus , 42300 Puncak Alam, Selangor, Malaysia
| | - Minkyung Jung
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine , Sendai 980-8575, Japan
| | - Tetsuro Matsunaga
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine , Sendai 980-8575, Japan
| | - Shigemoto Fujii
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine , Sendai 980-8575, Japan
| | - Tomohiro Sawa
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto 860-8556, Japan
| | - Motohiro Nishida
- Division of Cardiocirculatory Signaling, National Institute for Physiological Sciences (Okazaki Institute for Integrative Bioscience), National Institutes of Natural Sciences , Aichi 444-8787, Japan
| | - Yoshito Kumagai
- Environmental Biology Section, Faculty of Medicine, University of Tsukuba , Tsukuba, Ibaraki 305-8575, Japan
| | - Takaaki Akaike
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine , Sendai 980-8575, Japan
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21
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Na EJ, Jang HH, Kim GR. Review of Recent Studies and Research Analysis for Anti-oxidant and Anti-aging Materials. ACTA ACUST UNITED AC 2016. [DOI: 10.20402/ajbc.2016.0107] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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22
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Fu J, Cui Q, Yang B, Hou Y, Wang H, Xu Y, Wang D, Zhang Q, Pi J. The impairment of glucose-stimulated insulin secretion in pancreatic β-cells caused by prolonged glucotoxicity and lipotoxicity is associated with elevated adaptive antioxidant response. Food Chem Toxicol 2016; 100:161-167. [PMID: 28027979 DOI: 10.1016/j.fct.2016.12.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 12/06/2016] [Accepted: 12/14/2016] [Indexed: 11/17/2022]
Abstract
Type 2 diabetes (T2D) is a progressive disease characterized by sustained hyperglycemia and is frequently accompanied by hyperlipidemia. Deterioration of β-cell function in T2D patients may be caused, in part, by long-term exposure to high concentrations of glucose and/or lipids. We developed systems to study how chronic glucotoxicity and lipotoxicity might be linked to the impairment of glucose-stimulated insulin secretion (GSIS) machinery in pancreatic β-cells. INS-1 (832/13) were exposed to glucose and/or palmitate for up to 10 weeks. Chronic high glucose and/or palmitate exposure resulted in impaired GSIS accompanied by a dramatic increase in oxidative stress, as determined by basal intracellular peroxide levels. In addition, the GSIS-associated reactive oxygen species (ROS) signals, assessed as glucose-stimulated peroxide accumulation positively correlated with GSIS in glucose- and/or palmitate-exposed cells, as well as glucose-stimulated reductions in GSH/GSSG ratios. Furthermore, the impairment of GSIS caused by chronic high glucose and/or palmitate exposures were attributed to the induction of adaptive antioxidant response and mitochondrial uncoupling, which negatively regulates glucose-derived ROS generation. Taken together, persistent glucotoxicity- and/or lipotoxicity-mediated oxidative stress and subsequent adaptive antioxidant response impair glucose-derived ROS signaling and GSIS in pancreatic β-cells.
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Affiliation(s)
- Jingqi Fu
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Qi Cui
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Bei Yang
- Department of Histology and Embryology, School of Basic Medical Sciences, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Yongyong Hou
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Huihui Wang
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Yuanyuan Xu
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Difei Wang
- The First Affiliated Hospital, China Medical University, 155 Nanjingbei Street, Heping District, Shenyang, Liaoning, 110001, PR China
| | - Qiang Zhang
- Department of Environmental Health, Rollins School of Public Health, Emory University, 201 Dowman Drive, Atlanta, GA, 30322, USA
| | - Jingbo Pi
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China.
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Kumagai Y, Abiko Y. Environmental Electrophiles: Protein Adducts, Modulation of Redox Signaling, and Interaction with Persulfides/Polysulfides. Chem Res Toxicol 2016; 30:203-219. [DOI: 10.1021/acs.chemrestox.6b00326] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Yoshito Kumagai
- Environmental Biology Section, Faculty
of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Yumi Abiko
- Environmental Biology Section, Faculty
of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
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Methylmercury, an environmental electrophile capable of activation and disruption of the Akt/CREB/Bcl-2 signal transduction pathway in SH-SY5Y cells. Sci Rep 2016; 6:28944. [PMID: 27357941 PMCID: PMC4928048 DOI: 10.1038/srep28944] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/06/2016] [Indexed: 11/24/2022] Open
Abstract
Methylmercury (MeHg) modifies cellular proteins via their thiol groups in a process referred to as “S-mercuration”, potentially resulting in modulation of the cellular signal transduction pathway. We examined whether low-dose MeHg could affect Akt signaling involved in cell survival. Exposure of human neuroblastoma SH-SY5Y cells of up to 2 μM MeHg phosphorylated Akt and its downstream signal molecule CREB, presumably due to inactivation of PTEN through S-mercuration. As a result, the anti-apoptotic protein Bcl-2 was up-regulated by MeHg. The activation of Akt/CREB/Bcl-2 signaling mediated by MeHg was, at least in part, linked to cellular defence because either pretreatment with wortmannin to block PI3K/Akt signaling or knockdown of Bcl-2 enhanced MeHg-mediated cytotoxicity. In contrast, increasing concentrations of MeHg disrupted Akt/CREB/Bcl-2 signaling. This phenomenon was attributed to S-mercuration of CREB through Cys286 rather than Akt. These results suggest that although MeHg is an apoptosis-inducing toxicant, this environmental electrophile is able to activate the cell survival signal transduction pathway at lower concentrations prior to apoptotic cell death.
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25
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Abiko Y, Yoshida E, Ishii I, Fukuto JM, Akaike T, Kumagai Y. Involvement of reactive persulfides in biological bismethylmercury sulfide formation. Chem Res Toxicol 2015; 28:1301-6. [PMID: 25874357 DOI: 10.1021/acs.chemrestox.5b00101] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bismethylmercury sulfide (MeHg)2S has been found to be a detoxified metabolite of methylmercury (MeHg) that is produced by SH-SY5Y cells and in livers of rats exposed to MeHg. (MeHg)2S could be formed through the interactions between MeHg and sulfur species such as hydrogen sulfide (H2S or HS(-)), but the origin of its sulfur has not been fully identified. We herein examined the formation of (MeHg)2S through interactions between MeHg and persulfides, polysulfides, and protein preparations. Investigations using HPLC/atomic absorption spectrophotometry and EI-MS revealed that NaHS and Na2S4 react readily with MeHg to give (MeHg)2S, and similar results were found using GSH persulfide (GSSH) formed endogenously or generated enzymatically in vitro. (MeHg)2S was also formed by incubation of MeHg with liver and heart cytosolic fractions prepared from wild-type mice but not with those from mice lacking cystathionine γ-lyase (CSE) that catalyzes the formation of cysteine persulfide. Consistent with this, (MeHg)2S was detected in a variety of tissues taken from wild-type mice intraperitoneally injected with MeHg in vivo but not in those from MeHg-injected CSE knockout mice. By separating liver fractions by column chromatography, we found numerous proteins that contain persulfides: one of the proteins was identified as being glutathione S-transferase pi 1. These results indicate that the formation of (MeHg)2S can be attributed to interactions between MeHg and endogenous free persulfide species, as well as protein-bound cysteine persulfide.
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Affiliation(s)
| | | | - Isao Ishii
- §Department of Biochemistry, Keio University School of Pharmaceutical Sciences, Tokyo 105-8512, Japan
| | - Jon M Fukuto
- ∥Department of Chemistry, Sonoma State University, Rohnert Park, California 94928, United States
| | - Takaaki Akaike
- ⊥Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
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Yoshida E, Abiko Y, Kumagai Y. Glutathione adduct of methylmercury activates the Keap1-Nrf2 pathway in SH-SY5Y cells. Chem Res Toxicol 2014; 27:1780-6. [PMID: 25271560 DOI: 10.1021/tx5002332] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Methylmercury (MeHg) reacts readily with GSH, leading to the formation of a MeHg-SG adduct that is excreted into extracellular space through multidrug-resistance-associated protein (MRP), which is regulated by the transcription factor Nrf2. We previously reported that MeHg covalently modifies Keap1 and activates Nrf2 in human neuroblastoma SH-SY5Y cells. In the study presented here, we examined whether the MeHg-SG adduct could also modulate the Keap1-Nrf2 pathway because the formation of the Hg-S bond is believed to be reversible in the presence of a nucleophile. SH-SY5Y cells exposed to the synthetic ethyl monoester of the MeHg-SG adduct (which is hydrolyzed by cellular esterase(s) to give the MeHg-SG adduct) exhibited a concentration-dependent cellular toxicity that was enhanced by pretreatment with a specific MRP inhibitor. As expected, the MeHg-SG adduct was able to modify cellular proteins in the SH-SY5Y cells and purified Keap1. We also found that this prodrug, as well as MeHg, causes the cellular Keap1 in the cells to be modified, resulting in Nrf2 activation and, thereby, the upregulation of the downstream genes. These results suggest that the MeHg-SG adduct is not electrophilic but that it modifies protein thiols (including Keap1) through S-transmercuration and that rapid Nrf2-dependent excretion of the MeHg-SG adduct is essential in decreasing the cytotoxicity of MeHg.
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Affiliation(s)
- Eiko Yoshida
- Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba , 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
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27
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Kanda H, Shinkai Y, Kumagai Y. S-Mercuration of cellular proteins by methylmercury and its toxicological implications. J Toxicol Sci 2014; 39:687-700. [DOI: 10.2131/jts.39.687] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Hironori Kanda
- Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Yasuhiro Shinkai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba
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28
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The role of the Keap1/Nrf2 pathway in the cellular response to methylmercury. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2013; 2013:848279. [PMID: 23878621 PMCID: PMC3710591 DOI: 10.1155/2013/848279] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 05/26/2013] [Accepted: 06/03/2013] [Indexed: 12/26/2022]
Abstract
Methylmercury (MeHg) is an environmental electrophile that covalently modifies cellular proteins with reactive thiols, resulting in the formation of protein adducts. While such protein modifications, referred to as S-mercuration, are thought to be associated with the enzyme dysfunction and cellular damage caused by MeHg exposure, the current consensus is that (1) there is a cellular response to MeHg through the activation of NF-E2-related factor 2 (Nrf2) coupled to S-mercuration of its negative regulator, Kelch-like ECH-associated protein 1 (Keap1), and (2) the Keap1/Nrf2 pathway protects against MeHg toxicity. In this review, we introduce our findings and discuss the observations of other workers concerning the S-mercuration of cellular proteins by MeHg and the importance of the Keap1/Nrf2 pathway in protection against MeHg toxicity in cultured cells and mice.
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29
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Kanda H, Toyama T, Shinohara-Kanda A, Iwamatsu A, Shinkai Y, Kaji T, Kikushima M, Kumagai Y. S-Mercuration of rat sorbitol dehydrogenase by methylmercury causes its aggregation and the release of the zinc ion from the active site. Arch Toxicol 2012; 86:1693-702. [PMID: 22752181 DOI: 10.1007/s00204-012-0893-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 06/12/2012] [Indexed: 11/25/2022]
Abstract
We previously developed a screening method to identify proteins that undergo aggregation through S-mercuration by methylmercury (MeHg) and found that rat arginase I is a target protein for MeHg (Kanda et al. in Arch Toxicol 82:803-808, 2008). In the present study, we characterized another S-mercurated protein from a rat hepatic preparation that has a subunit mass of 42 kDa, thereby facilitating its aggregation. Two-dimensional SDS-polyacrylamide gel electrophoresis and subsequent peptide mass fingerprinting using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry revealed that the 42 kDa protein was NAD-dependent sorbitol dehydrogenase (SDH). With recombinant rat SDH, we found that MeHg is covalently bound to SDH through Cys44, Cys119, Cys129 and Cys164, resulting in the inhibition of its catalytic activity, release of zinc ions and facilitates protein aggregation. Mutation analysis indicated that Cys44, which ligates the active site zinc atom, and Cys129 play a crucial role in the MeHg-mediated aggregation of SDH. Pretreatment with the cofactor NAD, but not NADP or FAD, markedly prevented aggregation of SDH. Such a protective effect of NAD on the aggregation of SDH caused by MeHg is discussed.
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Affiliation(s)
- Hironori Kanda
- Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
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30
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Shinkai Y, Iwamoto N, Miura T, Ishii T, Cho AK, Kumagai Y. Redox cycling of 1,2-naphthoquinone by thioredoxin1 through Cys32 and Cys35 causes inhibition of its catalytic activity and activation of ASK1/p38 signaling. Chem Res Toxicol 2012; 25:1222-30. [PMID: 22587396 DOI: 10.1021/tx300069r] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1,2-Naphthoquinone (1,2-NQ) is an atmospheric chemical capable of (1) redox cycling with electron donors and (2) covalent modification of nucleophilic groups on proteins. In the present study, we investigated its interaction with the redox protein, thioredoxin1 (Trx1), which led to oxidative stress-dependent cell damage. In experiments with purified wild-type Trx1 and its double mutant (32S/35S Trx1), we found that incubation of Trx1 with 1,2-NQ resulted in a redox cycling reaction, generating superoxide and hydrogen peroxide involving Cys32 and Cys35 and an arylation reaction resulting in covalent modification of Lys85 together with a loss of Trx activity. A significant fraction of the lost Trx1 activity following interaction with 1,2-NQ was restored by dithiothreitol. Exposure of RAW264.7 cells to 1,2-NQ generated reactive oxygen species (ROS) and caused a decrease in Trx activity. Trx is a negative regulator of apoptosis signal-regulating kinase 1 (ASK1), and under the conditions of the experiment, 1,2-NQ activated ASK1 and p38, leading to PARP cleavage and apoptotic cell death that were blocked by pretreatment with polyethylene glycol-catalase. These results suggest that Trx1 readily undergoes oxidative modification by 1,2-NQ through the proximal thiols Cys32 and Cys35. It seems likely that ROS production concomitant with decline in cellular Trx activity plays a role in the activation of ASK1/p38 signaling to promote apoptotic cell death cause by 1,2-NQ exposure.
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Affiliation(s)
- Yasuhiro Shinkai
- Environmental Medicine Section, Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
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31
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Toyama T, Yoshida E, Shinkai Y, Kumagai Y. DNA microarray analysis of human neuroblastoma SH-SY5Y cells exposed to methylmercury. J Toxicol Sci 2012; 36:843-5. [PMID: 22129749 DOI: 10.2131/jts.36.843] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
To investigate the adaptive response to the environmental electrophile methylmercury (MeHg), we performed DNA microarray analysis of human neuroblastoma SH-SY5Y cells exposed to a sub-cytotoxic dose of MeHg (1 µM) for 6 hr. The expression of 15 genes increased 10-fold or more in response to MeHg. Four of these genes are associated with detoxification and excretion of MeHg into the extracellular space, and are regulated by transcription factor Nrf2 through the electrophile response element. Interestingly, Cullin3, a negative regulator of Nrf2, was identified as a down-regulated gene during MeHg exposure.
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Affiliation(s)
- Takashi Toyama
- Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
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32
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Toyama T, Shinkai Y, Yasutake A, Uchida K, Yamamoto M, Kumagai Y. Isothiocyanates reduce mercury accumulation via an Nrf2-dependent mechanism during exposure of mice to methylmercury. ENVIRONMENTAL HEALTH PERSPECTIVES 2011; 119:1117-22. [PMID: 21382770 PMCID: PMC3237354 DOI: 10.1289/ehp.1003123] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2010] [Accepted: 03/07/2011] [Indexed: 05/20/2023]
Abstract
BACKGROUND Methylmercury (MeHg) exhibits neurotoxicity through accumulation in the brain. The transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2) plays an important role in reducing the cellular accumulation of MeHg. OBJECTIVES We investigated the protective effect of isothiocyanates, which are known to activate Nrf2, on the accumulation of mercury after exposure to MeHg in vitro and in vivo. METHODS We used primary mouse hepatocytes in in vitro experiments and mice as an in vivo model. We used Western blotting, luciferase assays, atomic absorption spectrometry assays, and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assays, and we identified toxicity in mice based on hind-limb flaccidity and mortality. RESULTS The isothiocyanates 6-methylsulfinylhexyl isothiocyanate (6-HITC) and sulforaphane (SFN) activated Nrf2 and up-regulated downstream proteins associated with MeHg excretion, such as glutamate-cysteine ligase, glutathione S-transferase, and multidrug resistance-associated protein, in primary mouse hepatocytes. Under these conditions, intracellular glutathione levels increased in wild-type but not Nrf2-deficient primary mouse hepatocytes. Pretreatment with 6-HITC and SFN before MeHg exposure suppressed cellular accumulation of mercury and cytotoxicity in wild-type but not Nrf2-deficient primary mouse hepatocytes. In comparison, in vivo administration of MeHg to Nrf2-deficient mice resulted in increased sensitivity to mercury concomitant with an increase in mercury accumulation in the brain and liver. Injection of SFN before administration of MeHg resulted in a decrease in mercury accumulation in the brain and liver of wild-type, but not Nrf2-deficient, mice. CONCLUSIONS Through activation of Nrf2, 6-HITC and SFN can suppress mercury accumulation and intoxication caused by MeHg intake.
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Affiliation(s)
- Takashi Toyama
- Doctoral Programs in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
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33
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Eiguren-Fernandez A, Shinyashiki M, Schmitz DA, DiStefano E, Hinds W, Kumagai Y, Cho AK, Froines JR. Redox and electrophilic properties of vapor- and particle-phase components of ambient aerosols. ENVIRONMENTAL RESEARCH 2010; 110:207-12. [PMID: 20152964 PMCID: PMC2871538 DOI: 10.1016/j.envres.2010.01.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 01/26/2010] [Accepted: 01/28/2010] [Indexed: 05/21/2023]
Abstract
Particulate matter (PM) has been the primary focus of studies aiming to understand the relationship between the chemical properties of ambient aerosols and adverse health effects. Size and chemical composition of PM have been linked to their oxidative capacity which has been postulated to promote or exacerbate pulmonary and cardiovascular diseases. But in the last few years, new studies have suggested that volatile and semi-volatile components may also contribute to many adverse health effects. The objectives of this study were: (i) assess for the first time the redox and electrophilic potential of vapor-phase components of ambient aerosols and (ii) evaluate the relative contributions of particle- and vapor-fractions to the hazard of a given aerosol. To achieve these objectives vapor- and particle-phase samples collected in Riverside (CA) were subjected to three chemical assays to determine their redox and electrophilic capacities. The results indicate that redox active components are mainly associated with the particle-phase, while electrophilic compounds are found primarily in the vapor-phase. Vapor-phase organic extracts were also capable of inducing the stress responding protein, heme-oxygenase-1 (HO-1), in RAW264.7 murine macrophages. These results demonstrate the importance of volatile components in the overall oxidative and electrophilic capacity of aerosols, and point out the need for inclusion of vapors in future health and risk assessment studies.
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Reduction of arginase I activity and manganese levels in the liver during exposure of rats to methylmercury: a possible mechanism. Arch Toxicol 2008; 82:803-8. [PMID: 18488197 DOI: 10.1007/s00204-008-0307-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 04/22/2008] [Indexed: 10/22/2022]
Abstract
The toxicity of methylmercury (MeHg) is, in part, thought to be due to its interaction with thiol groups in a variety of enzymes, but the molecular targets of MeHg are poorly understood. Arginase I, an abundant manganese (Mn)-binding protein in the liver, requires Mn as an essential element to exhibit maximal enzyme activity. In the present study, we examined the effect of MeHg on hepatic arginase I in vivo and in vitro. Subcutaneous administration of MeHg (10 mg/kg) for 8 days to rats resulted in marked suppression of arginase I activity. With purified arginase I, we found that interaction of MeHg with arginase I caused the aggregation of arginase I as evaluated by centrifugation and subsequent precipitation, and then the reduction of catalytic activity. Experiments with organomercury column confirmed that arginase I has reactive thiols that are covalently bound to organomercury. While MeHg inhibited arginase I activity, Mn ions were released from this enzyme. These results suggest that MeHg-mediated suppression of hepatic arginase I activity in vivo is, at least in part, attributable to covalent modification of MeHg or substantial leakage of Mn ions from the active site.
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Toyama T, Sumi D, Shinkai Y, Yasutake A, Taguchi K, Tong KI, Yamamoto M, Kumagai Y. Cytoprotective role of Nrf2/Keap1 system in methylmercury toxicity. Biochem Biophys Res Commun 2007; 363:645-50. [PMID: 17904103 DOI: 10.1016/j.bbrc.2007.09.017] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 09/06/2007] [Indexed: 11/27/2022]
Abstract
Human exposure to methylmercury (MeHg) from contaminated fish is a potential health risk. Because of its chemical properties as a soft electrophile, we investigated the participation of Nrf2 in the cellular response to and protection against MeHg with SH-SY5Y cells and with primary mouse hepatocytes from Nrf2- and Keap1-deficient mice. Exposure of SH-SY5Y cells to MeHg activated Nrf2 through the binding of MeHg and Keap1. Nrf2 overexpression attenuated MeHg-induced cytotoxicity in SH-SY5Y cells. In addition, primary mouse hepatocytes extracted from Nrf2-deficient mouse was susceptible, and hepatocyte-specific conditional Keap1-deficient mouse was resistant to MeHg-induced cytotoxicity. Consistent with this data, MeHg was accumulated by Nrf2 deficiency and reduced by Keap1 deficiency. Our findings indicate that MeHg activates Nrf2 and the activation of Nrf2 is essential for reduction of MeHg toxicity by facilitating its excretion into extracellular space.
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MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Adaptor Proteins, Signal Transducing/physiology
- Animals
- Blotting, Western
- Cell Line, Tumor
- Cell Survival/drug effects
- Cells, Cultured
- Cytoskeletal Proteins/genetics
- Cytoskeletal Proteins/metabolism
- Cytoskeletal Proteins/physiology
- Dose-Response Relationship, Drug
- Hepatocytes/cytology
- Hepatocytes/drug effects
- Hepatocytes/metabolism
- Humans
- Kelch-Like ECH-Associated Protein 1
- Luciferases/genetics
- Luciferases/metabolism
- Methylmercury Compounds/metabolism
- Methylmercury Compounds/toxicity
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- NF-E2-Related Factor 2/genetics
- NF-E2-Related Factor 2/metabolism
- NF-E2-Related Factor 2/physiology
- Protein Binding
- RNA, Small Interfering/genetics
- Recombinant Fusion Proteins/metabolism
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Affiliation(s)
- Takashi Toyama
- Master's Program in Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8572, Japan
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36
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Kumagai Y, Wakayama T, Lib S, Shinohara A, Iwamatsu A, Sun G, Shimojo N. Zeta-crystallin catalyzes the reductive activation of 2,4,6-trinitrotoluene to generate reactive oxygen species: a proposed mechanism for the induction of cataracts. FEBS Lett 2000; 478:295-8. [PMID: 10930585 DOI: 10.1016/s0014-5793(00)01841-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Exposure to 2,4,6-trinitrotoluene (TNT) has been shown to cause induction of cataract in which oxidative stress plays a critical role. From bovine lens we purified to homogeneity and identified an enzyme that catalyzes the reduction of TNT, resulting in the production of reactive oxygen species. The final preparation of TNT reductase showed a single band with a subunit molecular weight of 38 kDa on SDS-PAGE. Sequence data from peptides obtained by digestion with lysylendopeptidase Achromobacter protease I (API) revealed that TNT reductase is identical to zeta-crystallin. Superoxide anions were formed during reduction of TNT by zeta-crystallin, though negligible enzyme activity or protein content for superoxide dismutase, a superoxide scavenging enzyme, was found in the lens. Thus, the present results suggest that the induction of cataracts by TNT may be associated with increased oxidative stress, as a result of reductive activation of TNT generating superoxide anions, there being minimal antioxidant enzyme activity for defense against reactive oxygen species exogenously produced in the lens.
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Affiliation(s)
- Y Kumagai
- Department of Environment Medicine, Institute of Community Medicine, Master's Program in Environmental Sciences, Tsukuba University, Ibaraki, Japan.
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37
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Kanda H, Kumagai Y, Nakajima H, Takenaka Y, Homma-Takeda S, Shimojo N. [Various changes in nitric oxide synthase and arginase II in rat kidney caused by inorganic mercury]. SANGYO EISEIGAKU ZASSHI = JOURNAL OF OCCUPATIONAL HEALTH 1998; 40:212-3. [PMID: 9836332 DOI: 10.1539/sangyoeisei.kj00001990620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- H Kanda
- Department of Environmental Medicine, University of Tsukuba, Ibaraki, Japan
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Shinyashiki M, Kumagai Y, Nakajima H, Nagafune J, Homma-Takeda S, Sagai M, Shimojo N. Differential changes in rat brain nitric oxide synthase in vivo and in vitro by methylmercury. Brain Res 1998; 798:147-55. [PMID: 9666107 DOI: 10.1016/s0006-8993(98)00400-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Alterations in mRNA level, protein content and enzyme activity for nitric oxide synthase (NOS) in the cerebrum and cerebellum during a continuous exposure of neurotoxic metal, methylmercury, were examined in Wistar rats. Subcutaneous (s.c.) administration of methylmercuric chloride (MMC, 10 mg kg-1 day-1, 8 days) resulted in significant increases with time of NOS activities in the cerebrum (1. 6-1.9-fold, 5-8 days) and cerebellum (1.4-fold, 8 days). RT-PCR and immunoblot analyses indicated that the increase in the enzyme activity caused by this metal appears to be due to increase in protein levels of neuronal NOS (nNOS), but not inducible NOS (iNOS) because little appreciable mRNA and protein for iNOS were seen during MMC exposure. The direct effect of mercuric compounds on nNOS activity in vitro was evaluated using 20,000xg supernatant from rat cerebellum homogenate. In contrast to the in vivo observation, inorganic-, alkyl-, and aryl-mercuric compound showed potent inhibition of nNOS activity with IC50 values of 11-43 microM, whereas dimethylmercury (DMM) was without effect on the enzyme activity. Further experiments indicated that the inhibition of nNOS by organomercurial occurred via thiol modification.
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Affiliation(s)
- M Shinyashiki
- Graduate School Doctoral Program in Medical Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305, Japan
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Naganuma A, Miura K, Tanaka-Kagawa T, Kitahara J, Seko Y, Toyoda H, Imura N. Overexpression of manganese-superoxide dismutase prevents methylmercury toxicity in HeLa cells. Life Sci 1998; 62:PL157-61. [PMID: 9519816 DOI: 10.1016/s0024-3205(98)00037-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
HeLa cells were stably transformed with plasmid constructs that allowed constitutive expression of antioxidant enzymes such as catalase, glutathione peroxidase (GSH-Px), Cu,Zn-superoxide dismutase (Cu,Zn-SOD) or Mn-superoxide dismutase (Mn-SOD) to examine the involvement of reactive oxygen generation in methylmercury toxicity. Overexpression of catalase, GSH-Px or Cu,Zn-SOD did not affect the sensitivity of HeLa cells against methylmercury. However, the sensitivity of HeLa cells against methylmercury was decreased by overexpression of Mn-SOD, an enzyme localized in matrix of mitochondria and which decomposes superoxide anions. These results suggest that formation of superoxide anions in the mitochondria might be involved in the mechanism of the cytotoxicity of methylmercury.
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Affiliation(s)
- A Naganuma
- Department of Public Health and Molecular Toxicology, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.
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Kumagai Y, Mizukado S, Nagafune J, Shinyashiki M, Homma-Takeda S, Shimojo N. Post-transcriptional elevation of mouse brain Mn-SOD protein by mercuric chloride. Brain Res 1997; 769:178-82. [PMID: 9374288 DOI: 10.1016/s0006-8993(97)00846-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Alterations in gene expression, protein content and enzyme activity of brain Mn-SOD following mercuric chloride (HgCl2) exposure were examined in ICR male mice. Subcutaneous administration of HgCl2 (1 mg Hg/kg) resulted in a significant increase (4-fold) in the brain Mn-SOD content at 6 h after injection while the total mercury concentration was about 0.11 microg/g of brain. The enhancement of Mn-SOD protein caused by HgCl2 was completely abolished by pretreatment with dexamethasone (3 mg/kg) 1 h prior to HgCl2 administration, suggesting involvement of inflammation in inorganic mercury-induced increase in the antioxidant enzyme. This increase in level of Mn-SOD content coincided with a substantial rise in the enzyme activity; however, Northern blot analysis revealed that the induction of protein level was not due to that of its gene expression. The results of the present study indicate that mouse brain Mn-SOD appears to undergo post-translational modification by the environmental toxic metal, and induction of the antioxidant enzyme could be of an initial response to the metal-induced oxidative stress.
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Affiliation(s)
- Y Kumagai
- Department of Environmental Medicine, Institute of Community Medicine, University of Tsukuba, Ibaraki, Japan.
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