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Kang B, Wang J, Guo S, Yang L. Mercury-induced toxicity: Mechanisms, molecular pathways, and gene regulation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 943:173577. [PMID: 38852866 DOI: 10.1016/j.scitotenv.2024.173577] [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: 11/30/2023] [Revised: 03/01/2024] [Accepted: 05/25/2024] [Indexed: 06/11/2024]
Abstract
Mercury is a well-known neurotoxicant for humans and wildlife. The epidemic of mercury poisoning in Japan has clearly demonstrated that chronic exposure to methylmercury (MeHg) results in serious neurological damage to the cerebral and cerebellar cortex, leading to the dysfunction of the central nervous system (CNS), especially in infants exposed to MeHg in utero. The occurrences of poisoning have caused a wide public concern regarding the health risk emanating from MeHg exposure; particularly those eating large amounts of fish may experience the low-level and long-term exposure. There is growing evidence that MeHg at environmentally relevant concentrations can affect the health of biota in the ecosystem. Although extensive in vivo and in vitro studies have demonstrated that the disruption of redox homeostasis and microtube assembly is mainly responsible for mercurial toxicity leading to adverse health outcomes, it is still unclear whether we could quantitively determine the occurrence of interaction between mercurial and thiols and/or selenols groups of proteins linked directly to outcomes, especially at very low levels of exposure. Furthermore, intracellular calcium homeostasis, cytoskeleton, mitochondrial function, oxidative stress, neurotransmitter release, and DNA methylation may be the targets of mercury compounds; however, the primary targets associated with the adverse outcomes remain to be elucidated. Considering these knowledge gaps, in this article, we conducted a comprehensive review of mercurial toxicity, focusing mainly on the mechanism, and genes/proteins expression. We speculated that comprehensive analyses of transcriptomics, proteomics, and metabolomics could enhance interpretation of "omics" profiles, which may reveal specific biomarkers obviously correlated with specific pathways that mediate selective neurotoxicity.
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Affiliation(s)
- Bolun Kang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, China
| | - Jinghan Wang
- 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
| | - Lixin Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, China.
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2
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Yamashita N, Uchiyama M, Yamagata R, Hwang GW. Methylmercury Induces Apoptosis in Mouse C17.2 Neural Stem Cells through the Induction of OSGIN1 Expression by NRF2. Int J Mol Sci 2024; 25:3886. [PMID: 38612696 PMCID: PMC11011283 DOI: 10.3390/ijms25073886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/24/2024] [Accepted: 03/28/2024] [Indexed: 04/14/2024] Open
Abstract
Methylmercury is a known environmental pollutant that exhibits severe neurotoxic effects. However, the mechanism by which methylmercury causes neurotoxicity remains unclear. To date, we have found that oxidative stress-induced growth inhibitor 1 (OSGIN1), which is induced by oxidative stress and DNA damage, is also induced by methylmercury. Therefore, in this study, we investigated the relationship between methylmercury toxicity and the induction of OSGIN1 expression using C17.2 cells, which are mouse brain neural stem cells. Methylmercury increased both OSGIN1 mRNA and protein levels in a time- and concentration-dependent manner. Moreover, these increases were almost entirely canceled out by pretreatment with actinomycin D, a transcription inhibitor. Furthermore, similar results were obtained from cells in which expression of the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) was suppressed, indicating that methylmercury induces OSGIN1 expression via NRF2. Methylmercury causes neuronal cell death by inducing apoptosis. Therefore, we next investigated the role of OSGIN1 in methylmercury-induced neuronal cell death using the activation of caspase-3, which is involved in apoptosis induction, as an indicator. As a result, the increase in cleaved caspase-3 (activated form) induced by methylmercury exposure was decreased by suppressing OSGIN1, and the overexpression of OSGIN1 further promoted the increase in cleaved caspase-3 caused by methylmercury. These results suggest, for the first time, that OSGIN1 is a novel factor involved in methylmercury toxicity, and methylmercury induces apoptosis in C17.2 cells through the induction of OSGIN1 expression by NRF2.
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Affiliation(s)
| | | | | | - Gi-Wook Hwang
- Laboratory of Environmental and Health Sciences, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Miyagi, Japan; (N.Y.); (R.Y.)
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3
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Ates I, Yılmaz AD, Buttari B, Arese M, Saso L, Suzen S. A Review of the Potential of Nuclear Factor [Erythroid-Derived 2]-like 2 Activation in Autoimmune Diseases. Brain Sci 2023; 13:1532. [PMID: 38002492 PMCID: PMC10669303 DOI: 10.3390/brainsci13111532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 10/07/2023] [Accepted: 10/11/2023] [Indexed: 11/26/2023] Open
Abstract
An autoimmune disease is the consequence of the immune system attacking healthy cells, tissues, and organs by mistake instead of protecting them. Inflammation and oxidative stress (OS) are well-recognized processes occurring in association with acute or chronic impairment of cell homeostasis. The transcription factor Nrf2 (nuclear factor [erythroid-derived 2]-like 2) is of major importance as the defense instrument against OS and alters anti-inflammatory activities related to different pathological states. Researchers have described Nrf2 as a significant regulator of innate immunity. Growing indications suggest that the Nrf2 signaling pathway is deregulated in numerous diseases, including autoimmune disorders. The advantageous outcome of the pharmacological activation of Nrf2 is an essential part of Nrf2-based chemoprevention and intervention in other chronic illnesses, such as neurodegeneration, cardiovascular disease, autoimmune diseases, and chronic kidney and liver disease. Nevertheless, a growing number of investigations have indicated that Nrf2 is already elevated in specific cancer and disease steps, suggesting that the pharmacological agents developed to mitigate the potentially destructive or transformative results associated with the protracted activation of Nrf2 should also be evaluated. The activators of Nrf2 have revealed an improvement in the progress of OS-associated diseases, resulting in immunoregulatory and anti-inflammatory activities; by contrast, the depletion of Nrf2 worsens disease progression. These data strengthen the growing attention to the biological properties of Nrf2 and its possible healing power on diseases. The evidence supporting a correlation between Nrf2 signaling and the most common autoimmune diseases is reviewed here. We focus on the aspects related to the possible effect of Nrf2 activation in ameliorating pathologic conditions based on the role of this regulator of antioxidant genes in the control of inflammation and OS, which are processes related to the progression of autoimmune diseases. Finally, the possibility of Nrf2 activation as a new drug development strategy to target pathogenesis is proposed.
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Affiliation(s)
- Ilker Ates
- Department of Pharmaceutical Toxicology, Faculty of Pharmacy, Ankara University, Degol Str. No. 4, 06560 Ankara, Turkey
| | - Ayşe Didem Yılmaz
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, Degol Str. No. 4, 06560 Ankara, Turkey; (A.D.Y.); (S.S.)
| | - Brigitta Buttari
- Department of Cardiovascular and Endocrine-Metabolic Diseases and Aging, Italian National Institute of Health, 00161 Rome, Italy;
| | - Marzia Arese
- Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, Piazzae Aldo Moro 5, 00185 Rome, Italy;
| | - Luciano Saso
- Department of Physiology and Pharmacology ‘‘Vittorio Erspamer”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
| | - Sibel Suzen
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, Degol Str. No. 4, 06560 Ankara, Turkey; (A.D.Y.); (S.S.)
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4
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Li J, Arest S, Olszowy B, Gordon J, Barrero CA, Perez-Leal O. CRISPR/Cas9-Based Screening of FDA-Approved Drugs for NRF2 Activation: A Novel Approach to Discover Therapeutics for Non-Alcoholic Fatty Liver Disease. Antioxidants (Basel) 2023; 12:1363. [PMID: 37507903 PMCID: PMC10375998 DOI: 10.3390/antiox12071363] [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: 06/05/2023] [Revised: 06/16/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
With the rising prevalence of obesity, non-alcoholic fatty liver disease (NAFLD) now affects 20-25% of the global population. NAFLD, a progressive condition associated with oxidative stress, can result in cirrhosis and liver cancer in 10% and 3% of patients suffering NAFLD, respectively. Therapeutic options are currently limited, emphasizing the need for novel treatments. In this study, we examined the potential of activating the transcription factor NRF2, a crucial player in combating oxidative stress, as an innovative approach to treating NAFLD. Utilizing a CRISPR/Cas9-engineered human HEK293T cell line, we were able to monitor the expression of heme oxygenase-1 (HMOX1), an NRF2 target, using a Nanoluc luciferase tag. Our model was validated using a known NRF2 activator, after which we screened 1200 FDA-approved drugs, unearthing six compounds (Disulfiram, Thiostrepton, Auranofin, Thimerosal, Halofantrine, and Vorinostat) that enhanced NRF2 activity and antioxidant response. These compounds demonstrated protective effects against oxidative stress induced by hydrogen peroxide and lipid droplets accumulation in vitro with hepatoma HUH-7 cells. Our study underscores the utility of CRISPR/Cas9 tagging with Nanoluc luciferase in identifying potential NRF2 activators, paving the way for potential NAFLD therapeutics.
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Affiliation(s)
| | | | | | | | | | - Oscar Perez-Leal
- Department of Pharmaceutical Sciences, Moulder Center for Drug Discovery, School of Pharmacy, Temple University, Philadelphia, PA 19140, USA
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5
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Trabelsi W, Fouzai C, Telahigue K, Chetoui I, Nechi S, Chelbi E, Zrelli S, Soudani N. The potential adverse effects of acrylamide on the oxidative stress response, fatty acids profile, and histopathological aspect of the Mediterranean Holothuria forskali respiratory tree. ENVIRONMENTAL TOXICOLOGY 2023; 38:159-171. [PMID: 36178721 DOI: 10.1002/tox.23674] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 09/05/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Acrylamide (ACR), organic compound, has been widely used owing to its broad spectrum of chemical and industrial applications. This study aims at evaluating the response of the antioxidant defense system, fatty acid composition and histopathological aspect in the respiratory trees of Holothuria forskali against ACR exposure under laboratory conditions. Holothuries were exposed to 5, 10, and 20 mg L-1 ACR concentrations for 5 days. A significant increase in n-6 polyunsaturated fatty acids levels especially the arachidonic acid (ARA, C20:4n-6) and its precursor linoleic acid (LA, C18:2n-6) in ACR-treated organisms. Regarding the n-3 levels, eicosapentaenoic acid (EPA, C20:5n-3) levels were increased in treated groups despite an acute decrease in docosahexaenoic acid (DHA, C22:6n-3) levels was observed. Our results showed a significant increase in hydrogen peroxide, malondialdehyde, protein carbonyl, and metallothionein levels along with an alteration of the antioxidants status in all treated sea cucumbers. The exposure to ACR prompted the inhibition of Acetylcholinesterase activity in a concentration-dependent manner. The histopathological aspect was marked especially with the infiltration of coelomic cells which confirms our biochemical findings. Our study provided novel insights to create a link between redox status and fatty acid composition disruptions to better understand ACR-triggered toxicity.
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Affiliation(s)
- Wafa Trabelsi
- Laboratory of Ecology, Biology, and Physiology of Aquatic Organisms, Department of Biology, Tunis Faculty of Sciences, University of Tunis El Manar, Tunis, Tunisia
| | - Chaima Fouzai
- Laboratory of Ecology, Biology, and Physiology of Aquatic Organisms, Department of Biology, Tunis Faculty of Sciences, University of Tunis El Manar, Tunis, Tunisia
| | - Khaoula Telahigue
- Laboratory of Ecology, Biology, and Physiology of Aquatic Organisms, Department of Biology, Tunis Faculty of Sciences, University of Tunis El Manar, Tunis, Tunisia
| | - Imene Chetoui
- Laboratory of Ecology, Biology, and Physiology of Aquatic Organisms, Department of Biology, Tunis Faculty of Sciences, University of Tunis El Manar, Tunis, Tunisia
| | - Salwa Nechi
- Anatomy and Cytology Service, CHU Mohamed Taher Maamouri Hospital, Nabeul, Tunisia
| | - Emna Chelbi
- Anatomy and Cytology Service, CHU Mohamed Taher Maamouri Hospital, Nabeul, Tunisia
| | - Sonia Zrelli
- University of Carthage, Faculty of Sciences of Bizerte, Laboratory of Environment Biomonitoring, Hydrobiology Unit, Zarzouna, Tunisia
| | - Nejla Soudani
- Laboratory of Ecology, Biology, and Physiology of Aquatic Organisms, Department of Biology, Tunis Faculty of Sciences, University of Tunis El Manar, Tunis, Tunisia
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Takanezawa Y, Sakai K, Nakamura R, Ohshiro Y, Uraguchi S, Kiyono M. Inhibition of p38 Mitogen-Activated Protein Kinases Attenuates Methylmercury Toxicity in SH-SY5Y Neuroblastoma Cells. Biol Pharm Bull 2023; 46:1203-1210. [PMID: 37661399 DOI: 10.1248/bpb.b23-00014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Methylmercury (MeHg) is a toxic metal that causes irreversible damage to the nervous system, making it a risk factor for neuronal degeneration and diseases. MeHg activates various cell signaling pathways, particularly the mitogen-activated protein kinase (MAPK) cascades, which are believed to be important determinants of stress-induced cell fate. However, little is known about the signaling pathways that mitigate the neurotoxic effects of MeHg. Herein, we showed that pretreatment with a p38 MAPK-specific inhibitor, SB203580, attenuates MeHg toxicity in human neuroblastoma SH-SY5Y cells, whereas pretreatment with the extracellular signaling-regulated kinase inhibitor U0126 and the c-Jun N-terminal kinase inhibitor SP600125 does not. Specifically, we quantified the levels of intracellular mercury (Hg) and found that pretreatment with SB203580 reduced Hg levels compared to MeHg treatment alone. Further analysis showed that pretreatment with SB203580 increased multidrug resistance-associated protein 2 (MRP2) mRNA levels after MeHg treatment. These results indicate that detoxification of MeHg by p38 MAPK inhibitors may involve an efflux function of MeHg by inducing MRP2 expression.
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Affiliation(s)
| | - Kazuma Sakai
- Department of Public Health, School of Pharmacy, Kitasato University
| | - Ryosuke Nakamura
- Department of Public Health, School of Pharmacy, Kitasato University
| | - Yuka Ohshiro
- Department of Public Health, School of Pharmacy, Kitasato University
| | - Shimpei Uraguchi
- Department of Public Health, School of Pharmacy, Kitasato University
| | - Masako Kiyono
- Department of Public Health, School of Pharmacy, Kitasato University
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7
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Hatano M, Hatamiya S, Miyara M, Kotake Y. Tributyltin activates the Keap1-Nrf2 pathway via a macroautophagy-independent reduction in Keap1. J Toxicol Sci 2023; 48:161-168. [PMID: 36858641 DOI: 10.2131/jts.48.161] [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: 03/03/2023]
Abstract
Tributyltin (TBT) is an environmental chemical, which was used as an antifouling agent for ships. Although its use has been banned, it is still persistently present in ocean sediments. Although TBT reportedly causes various toxicity in mammals, few studies on the mechanisms of biological response against TBT toxicity exist. The well-established Keap1-Nrf2 pathway is activated as a cytoprotective mechanism under stressful conditions. The relationship between TBT and the Keap1-Nrf2 pathway remains unclear. In the present study, we evaluated the effect of TBT on the Keap1-Nrf2 pathway. TBT reduced Keap1 protein expression in Neuro2a cells, a mouse neuroblastoma cell line, after 6 hr without altering mRNA expression levels. TBT also promoted the nuclear translocation of Nrf2, a transcription factor for antioxidant proteins, after 12 hr and augmented the expression of heme oxygenase 1, a downstream protein of Nrf2. Furthermore, TBT decreased Keap1 levels in mouse embryonic fibroblast (MEF) cells, with the knockout of Atg5, which is essential for macroautophagy, as well as in wild-type MEF cells. These results suggest that TBT activates the Keap1-Nrf2 pathway via the reduction in the Keap1 protein level in a macroautophagy-independent manner. The Keap1-Nrf2 pathway is activated by conformational changes in Keap1 induced by reactive oxygen species or electrophiles. Furthermore, any unutilized Keap1 protein is degraded by macroautophagy. Understanding the novel mechanism governing the macroautophagy-independent reduction in Keap1 by TBT may provide insights into the unresolved biological response mechanism against TBT toxicity and the activation mechanism of the Keap1-Nrf2 pathway.
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Affiliation(s)
- Misaki Hatano
- Graduate School of Biomedical and Health Sciences, Hiroshima University
| | - Shunichi Hatamiya
- Graduate School of Biomedical and Health Sciences, Hiroshima University
| | - Masatsugu Miyara
- Graduate School of Biomedical and Health Sciences, Hiroshima University
| | - Yaichiro Kotake
- Graduate School of Biomedical and Health Sciences, Hiroshima University
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8
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Akiyama M, Shinkai Y, Yamakawa H, Kim YG, Kumagai Y. Potentiation of methylmercury toxicity by combined metal exposure: In vitro and in vivo models of a restricted metal exposome. CHEMOSPHERE 2022; 299:134374. [PMID: 35318019 DOI: 10.1016/j.chemosphere.2022.134374] [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: 12/22/2021] [Revised: 03/05/2022] [Accepted: 03/17/2022] [Indexed: 06/14/2023]
Abstract
Methylmercury (MeHg) is a prevalent toxic metal that readily modifies protein thiols. Reactive persulfides that play a role in redox homeostasis are able to inactivate this metal through sulfur adduct formation. Although humans are exposed to other metals that could consume reactive persulfides on a daily basis, the health effects of combined exposure to MeHg and other metals remain unexplored. This study aimed to examine potential MeHg toxicity during exposure to MeHg with other metals capable of consuming reactive persulfides. We designed a simple system to assess the risk of combined exposure to metals based on reactivity to reactive persulfides and mercury accumulation. Among the metals examined in a cell-free system, copper, cadmium, nickel, and MeHg consumed Na2S2, used as a model of reactive persulfides, whereas zinc, iron, lithium, strontium, tin, and aluminum did not. In HepG2 cells, binary exposure to MeHg and copper, but not aluminum, increased the consumption of extracellular reactive persulfides. Binary exposure exacerbated MeHg-induced cytotoxicity by promoting the modification of intracellular proteins by MeHg. In a mouse model, binary exposure to MeHg and copper resulted in elevated mercury accumulation in the fetuses and placenta of pregnant mice, as well as the brain and liver of non-pregnant mice. Our study suggests that MeHg sensitivity can be increased by combined exposure with other electrophilic metals. In particular, binary exposure to MeHg and copper during pregnancy exacerbated mercury accumulation in offspring.
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Affiliation(s)
- Masahiro Akiyama
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan; Research Center for Drug Discovery, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University, Tokyo, 105-8512, Japan
| | - Yasuhiro Shinkai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan
| | - Hiroto Yamakawa
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan
| | - Yun-Gi Kim
- Research Center for Drug Discovery, Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University, Tokyo, 105-8512, Japan
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan.
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9
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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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10
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Shimizu K, Horie M, Tabei Y, Kashiwada S. Proinflammatory response caused by lead nanoparticles triggered by engulfed nanoparticles. ENVIRONMENTAL TOXICOLOGY 2021; 36:2040-2050. [PMID: 34189835 DOI: 10.1002/tox.23321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 06/18/2021] [Indexed: 06/13/2023]
Abstract
In this study, the cellular effects of lead (Pb) nanoparticles with a primary particle size of 80 nm were evaluated in two types of cell lines: human lung carcinoma A549 and macrophage-differentiated THP-1 cells (dTHP-1). The cellular responses induced by the Pb nanoparticles varied among the cell types. Exposure to Pb nanoparticles for 24 h at a concentration of 100 μg/ml induced interleukin-8 (IL-8) expression in dTHP-1 cells. Induction of IL-8 expression in A549 was lower than dTHP-1 cells. Pb nanoparticles also induced the gene expression of heme oxygenase-1 in dTHP-1 cells but not in A549 cells. Though cellular uptake of Pb nanoparticles was observed in both the cell types, the amount of internalized Pb particles was lower in A549 cells than that in dTHP-1 cells. Gene expression of metallothionein 2A was remarkably enhanced by Pb nanoparticle exposure in dTHP-1 cells. Compared with Pb nanoparticles, induction of cytokines caused by lead nitrate (Pb[NO3 ]2 ), a water-soluble Pb compound, was smaller. In conclusion, the present study revealed that Pb nanoparticles induced a stronger cellular response than Pb(NO3 )2 , primarily by eliciting cytokine production, in a cell type-dependent manner.
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Affiliation(s)
- Kaori Shimizu
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, Kagawa, Japan
- Graduate School of Life Sciences, Toyo University, Itakura, Gunma, Japan
| | - Masanori Horie
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, Kagawa, Japan
| | - Yosuke Tabei
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, Kagawa, Japan
| | - Shosaku Kashiwada
- Graduate School of Life Sciences, Toyo University, Itakura, Gunma, Japan
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11
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Ferrer B, Suresh H, Santamaria A, Rocha JB, Bowman AB, Aschner M. The antioxidant role of STAT3 in methylmercury-induced toxicity in mouse hypothalamic neuronal GT1-7 cell line. Free Radic Biol Med 2021; 171:245-259. [PMID: 34010664 PMCID: PMC8217327 DOI: 10.1016/j.freeradbiomed.2021.05.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/04/2021] [Accepted: 05/13/2021] [Indexed: 12/27/2022]
Abstract
Oxidative stress, impairment of antioxidant defenses, and disruption of calcium homeostasis are associated with the toxicity of methylmercury (MeHg). Yet, the relative contribution and interdependence of these effects and other molecular mechanisms that mediate MeHg-induced neurotoxicity remain uncertain. The signal transducer and activator of transcription 3 (STAT3) is a transcription factor that regulates the expression of anti-apoptotic and cell cycle progression genes. In addition to its role in cell growth and survival, STAT3 regulates redox homeostasis and prevents oxidative stress by the modulation of nuclear genes that encode for electron transport complexes (ETC) and antioxidant enzymes. Here we tested the hypothesis that STAT3 contributes to the orchestration of the antioxidant defense response against MeHg injury. We show that MeHg (>1 μM) exposure induced STAT3 activation within 1 h and beyond in mouse hypothalamic neuronal GT1-7 cells in a concentration-and time-dependent manner. Pharmacological inhibition of STAT3 phosphorylation exacerbated MeHg-induced reactive oxygen species (ROS) production and antioxidant responses. Finally, treatment with the antioxidant Trolox demonstrated that MeHg-induced STAT3 activation is mediated, at least in part, by MeHg-induced ROS generation. Combined, our results demonstrated a role for the STAT3 signaling pathway as an early response to MeHg-induced oxidative stress.
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Affiliation(s)
- Beatriz Ferrer
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, 10461, Bronx, NY, USA.
| | - Harshini Suresh
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, 10461, Bronx, NY, USA.
| | - Abel Santamaria
- Laboratorio de Aminoácidos Excitadores, Instituto Nacional de Neurología y Neurocirugía, 14269, Mexico City, Mexico.
| | - João Batista Rocha
- Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria, Santa Maria, Brazil.
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN, United States.
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, 10461, Bronx, NY, USA; IM Sechenov First Moscow State Medical University, Moscow, Russia, Institute of Cellular and Intracellular Symbiosis, Russian Academy of Sciences, Orenburg, Russia.
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12
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Wei Y, Ni L, Pan J, Li X, Xu B, Deng Y, Yang T, Liu W. The Roles of Oxidative Stress in Regulating Autophagy in Methylmercury-induced Neurotoxicity. Neuroscience 2021; 469:175-190. [PMID: 34174372 DOI: 10.1016/j.neuroscience.2021.06.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 06/16/2021] [Accepted: 06/17/2021] [Indexed: 12/24/2022]
Abstract
Methylmercury (MeHg) is a potential neurotoxin that is highly toxic to the human central nervous system. Although MeHg neurotoxicity has been widely studied, the mechanism of MeHg neurotoxicity has not yet been fully elucidated. Some research evidence suggests that oxidative stress and autophagy are important molecular mechanisms of MeHg-induced neurotoxicity. Researchers have widely accepted that oxidative stress regulates the autophagy pathway. The current study reviews the activation of Nuclear factor-erythroid-2-related factor (Nrf2)-related oxidative stress pathways and autophagy signaling pathways in the case of MeHg neurotoxicity. In addition, autophagy mainly plays a role in the neurotoxicity of MeHg through mTOR-dependent and mTOR-independent autophagy signaling pathways. Finally, the regulation of autophagy by reactive oxygen species (ROS) and Nrf2 in MeHg neurotoxicity was explored in this review, providing a new concept for the study of the neurotoxicity mechanism of MeHg.
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Affiliation(s)
- Yanfeng Wei
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, China
| | - Linlin Ni
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, China
| | - Jingjing Pan
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, China
| | - Xiaoyang Li
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, China
| | - Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, China
| | - Yu Deng
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, China
| | - Tianyao Yang
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, China
| | - Wei Liu
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, China.
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13
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Mechanisms of oxidative stress in methylmercury-induced neurodevelopmental toxicity. Neurotoxicology 2021; 85:33-46. [PMID: 33964343 DOI: 10.1016/j.neuro.2021.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/02/2021] [Accepted: 05/03/2021] [Indexed: 12/15/2022]
Abstract
Methylmercury (MeHg) is a long-lasting organic environmental pollutant that poses a great threat to human health. Ingestion of seafood containing MeHg is the most important way by which it comes into contact with human body, where the central nervous system (CNS) is the primary target of MeHg toxicity. During periods of pre-plus postnatal, in particular, the brain of offspring is vulnerable to specific developmental insults that result in abnormal neurobehavioral development, even without symptoms in mothers. While many studies on neurotoxic effects of MeHg on the developing brain have been conducted, the mechanisms of oxidative stress in MeHg-induced neurodevelopmental toxicity is less clear. Hitherto, no single process can explain the many effects observed in MeHg-induced neurodevelopmental toxicity. This review summarizes the possible mechanisms of oxidative stress in MeHg-induced neurodevelopmental toxicity, highlighting modulation of Nrf2/Keap1/Notch1, PI3K/AKT, and PKC/MAPK molecular pathways as well as some preventive drugs, and thus contributes to the discovery of endogenous and exogenous molecules that can counteract MeHg-induced neurodevelopmental toxicity.
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14
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The Role of Toxic Metals and Metalloids in Nrf2 Signaling. Antioxidants (Basel) 2021; 10:antiox10050630. [PMID: 33918986 PMCID: PMC8142989 DOI: 10.3390/antiox10050630] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/13/2021] [Accepted: 04/14/2021] [Indexed: 12/18/2022] Open
Abstract
Nuclear factor erythroid 2-related factor 2 (Nrf2), an emerging regulator of cellular resistance to oxidants, serves as one of the key defensive factors against a range of pathological processes such as oxidative damage, carcinogenesis, as well as various harmful chemicals, including metals. An increase in human exposure to toxic metals via air, food, and water has been recently observed, which is mainly due to anthropogenic activities. The relationship between environmental exposure to heavy metals, particularly cadmium (Cd), lead (Pb), mercury (Hg), and nickel (Ni), as well as metaloid arsenic (As), and transition metal chromium (Cr), and the development of various human diseases has been extensively investigated. Their ability to induce reactive oxygen species (ROS) production through direct and indirect actions and cause oxidative stress has been documented in various organs. Taking into account that Nrf2 signaling represents an important pathway in maintaining antioxidant balance, recent research indicates that it can play a dual role depending on the specific biological context. On one side, Nrf2 represents a potential crucial protective mechanism in metal-induced toxicity, but on the other hand, it can also be a trigger of metal-induced carcinogenesis under conditions of prolonged exposure and continuous activation. Thus, this review aims to summarize the state-of-the-art knowledge regarding the functional interrelation between the toxic metals and Nrf2 signaling.
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15
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Abiko Y, Katayama Y, Akiyama M, Kumagai Y. Lipophilic compounds in garlic decrease the toxicity of methylmercury by forming sulfur adducts. Food Chem Toxicol 2021; 150:112061. [PMID: 33587975 DOI: 10.1016/j.fct.2021.112061] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 01/26/2021] [Accepted: 02/09/2021] [Indexed: 12/28/2022]
Abstract
Garlic (Allium sativum L.) contains numerous sulfur compounds. We have previously found that reactive sulfur species such as glutathione persulfide, glutathione polysulfide, protein-bound persulfides, and hydrogen sulfide can bind to methylmercury to give bismethylmercury sulfide, which is less toxic than methylmercury. It was not clear, however, whether such reactive sulfur species are present in garlic. The aim of the study presented here was to determine whether garlic contains reactive sulfur species that can bind to methylmercury. We extracted garlic with organic solvents and then performed silica gel column chromatography to separate constituents that could cause bismethylmercury sulfide to form. We found numerous garlic constituents could bind to methylmercury to form bismethylmercury sulfide. A hexane extract of garlic decreased methylmercury cytotoxicity in vitro and body weight loss in mice. The results suggest that ingesting garlic may decrease methylmercury toxicity by causing the formation of sulfur adducts that inhibit adverse reactions.
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Affiliation(s)
- Yumi Abiko
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan
| | - Yusuke Katayama
- Master's Program in Medical Sciences, Graduate School of Comprehensive Human Sciences, 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
| | - Yoshito Kumagai
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
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16
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Behl T, Kaur I, Sehgal A, Sharma E, Kumar A, Grover M, Bungau S. Unfolding Nrf2 in diabetes mellitus. Mol Biol Rep 2021; 48:927-939. [PMID: 33389540 DOI: 10.1007/s11033-020-06081-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 12/10/2020] [Indexed: 11/24/2022]
Abstract
In spite of much awareness, diabetes mellitus continues to remain one of major reasons for mortality and morbidity rate all over the globe. Free radicals cause oxidative stress which is responsible for causing diabetes. The recent advancements in elucidation of ARE/keap1/Nrf2 pathway can help in better understanding of diabetes mellitus. Various clinical trials and animal studies have shown the promising effect of Nrf2 pathway in reversing diabetes by counteracting with the oxidative stress produced. The gene is known to dissociate from Keap1 on coming in contact with such stresses to show preventive and prognosis effect. The Nrf2 gene has been marked as a molecular player in dealing with wide intracellular as well as extracellular cellular interactions in different diseases. The regulation of this gene gives some transcription factor that contain antioxidant response elements (ARE) in their promoter region and thus are responsible for encoding certain proteins involved in regulation of metabolic and detoxifying enzymes.
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Affiliation(s)
- Tapan Behl
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India.
| | - Ishnoor Kaur
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India
| | - Aayush Sehgal
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India
| | - Eshita Sharma
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India
| | - Arun Kumar
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India
| | - Madhuri Grover
- B.S. Anangpuria Institute of Pharmacy, Alampur, Haryana, India
| | - Simona Bungau
- Department of Pharmacy, Faculty of Medicine and Pharmacy, University of Oradea, Oradea, Romania
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17
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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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18
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Gunderson JT, Peppriell AE, Vorojeikina D, Rand MD. Tissue-specific Nrf2 signaling protects against methylmercury toxicity in Drosophila neuromuscular development. Arch Toxicol 2020; 94:4007-4022. [PMID: 32816092 DOI: 10.1007/s00204-020-02879-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 08/12/2020] [Indexed: 02/07/2023]
Abstract
Methylmercury (MeHg) can elicit cognitive and motor deficits due to its developmental neuro- and myotoxic properties. While previous work has demonstrated that Nrf2 antioxidant signaling protects from MeHg toxicity, in vivo tissue-specific studies are lacking. In Drosophila, MeHg exposure shows greatest developmental toxicity in the pupal stage resulting in failed eclosion (emergence of adults) and an accompanying 'myosphere' phenotype in indirect flight muscles (IFMs). To delineate tissue-specific contributions to MeHg-induced motor deficits, we investigated the potential of Nrf2 signaling in either muscles or neurons to moderate MeHg toxicity. Larva were exposed to various concentrations of MeHg (0-20 µM in food) in combination with genetic modulation of the Nrf2 homolog cap-n-collar C (CncC), or its negative regulator Keap1. Eclosion behavior was evaluated in parallel with the morphology of two muscle groups, the thoracic IFMs and the abdominal dorsal internal oblique muscles (DIOMs). CncC signaling activity was reported with an antioxidant response element construct (ARE-GFP). We observed that DIOMs are distinguished by elevated endogenous ARE-GFP expression, which is only transiently seen in the IFMs. Dose-dependent MeHg reductions in eclosion behavior parallel formation of myospheres in the DIOMs and IFMs, while also increasing ARE-GFP expression in the DIOMs. Modulating CncC signaling via muscle-specific Keap1 knockdown and upregulation gives a rescue and exacerbation, respectively, of MeHg effects on eclosion and myospheres. Interestingly, muscle-specific CncC upregulation and knockdown both induce lethality. In contrast, neuron-specific upregulation of CncC, as well as Keap1 knockdown, rescued MeHg effects on eclosion and myospheres. Our findings indicate that enhanced CncC signaling localized to either muscles or neurons is sufficient to rescue muscle development and neuromuscular function from a MeHg insult. Additionally, there may be distinct roles for CncC signaling in myo-morphogenesis.
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Affiliation(s)
- Jakob T Gunderson
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Ashley E Peppriell
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Daria Vorojeikina
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Matthew D Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
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19
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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: 136] [Impact Index Per Article: 34.0] [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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20
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Zheng F, Gonçalves FM, Abiko Y, Li H, Kumagai Y, Aschner M. Redox toxicology of environmental chemicals causing oxidative stress. Redox Biol 2020; 34:101475. [PMID: 32336668 PMCID: PMC7327986 DOI: 10.1016/j.redox.2020.101475] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 12/17/2022] Open
Abstract
Living organisms are surrounded with heavy metals such as methylmercury, manganese, cobalt, cadmium, arsenic, as well as pesticides such as deltamethrin and paraquat, or atmospheric pollutants such as quinone. Extensive studies have demonstrated a strong link between environmental pollutants and human health. Redox toxicity is proposed as one of the main mechanisms of chemical-induced pathology in humans. Acting as both a sensor of oxidative stress and a positive regulator of antioxidants, the nuclear factor erythroid 2-related factor 2 (NRF2) has attracted recent attention. However, the role NRF2 plays in environmental pollutant-induced toxicity has not been systematically addressed. Here, we characterize NRF2 function in response to various pollutants, such as metals, pesticides and atmospheric quinones. NRF2 related signaling pathways and epigenetic regulations are also reviewed.
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Affiliation(s)
- Fuli Zheng
- Department of Preventive Medicine, School of Public Health, Fujian Medical University, Fuzhou, Fujian, 350122, China; Department of Molecular Pharmacology, Albert Einstein College of Medicine, Forchheimer 209, 1300 Morris Park Avenue, Bronx, NY, 10461, United States.
| | - Filipe Marques Gonçalves
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Forchheimer 209, 1300 Morris Park Avenue, Bronx, NY, 10461, United States
| | - Yumi Abiko
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, 305-8575, Japan
| | - Huangyuan Li
- Department of Preventive Medicine, School of Public Health, Fujian Medical University, Fuzhou, Fujian, 350122, China.
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, 305-8575, Japan.
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Forchheimer 209, 1300 Morris Park Avenue, Bronx, NY, 10461, United States.
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21
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Dayalan Naidu S, Dinkova-Kostova AT. KEAP1, a cysteine-based sensor and a drug target for the prevention and treatment of chronic disease. Open Biol 2020; 10:200105. [PMID: 32574549 PMCID: PMC7333886 DOI: 10.1098/rsob.200105] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 05/22/2020] [Indexed: 12/29/2022] Open
Abstract
Redox imbalance and persistent inflammation are the underlying causes of most chronic diseases. Mammalian cells have evolved elaborate mechanisms for restoring redox homeostasis and resolving acute inflammatory responses. One prominent mechanism is that of inducing the expression of antioxidant, anti-inflammatory and other cytoprotective proteins, while also suppressing the production of pro-inflammatory mediators, through the activation of transcription factor nuclear factor-erythroid 2 p45-related factor 2 (NRF2). At homeostatic conditions, NRF2 is a short-lived protein, which avidly binds to Kelch-like ECH-associated protein 1 (KEAP1). KEAP1 functions as (i) a substrate adaptor for a Cullin 3 (CUL3)-based E3 ubiquitin ligase that targets NRF2 for ubiquitination and proteasomal degradation, and (ii) a cysteine-based sensor for a myriad of physiological and pharmacological NRF2 activators. Here, we review the intricate molecular mechanisms by which KEAP1 senses electrophiles and oxidants. Chemical modification of specific cysteine sensors of KEAP1 results in loss of NRF2-repressor function and alterations in the expression of NRF2-target genes that encode large networks of diverse proteins, which collectively restore redox balance and resolve inflammation, thus ensuring a comprehensive cytoprotection. We focus on the cyclic cyanoenones, the most potent NRF2 activators, some of which are currently in clinical trials for various pathologies characterized by redox imbalance and inflammation.
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Affiliation(s)
- Sharadha Dayalan Naidu
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, School of Medicine, University of Dundee, Dundee, UK
| | - Albena T. Dinkova-Kostova
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, School of Medicine, University of Dundee, Dundee, UK
- Department of Pharmacology and Molecular Sciences and Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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22
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Akiyama M, Unoki T, Yoshida E, Ding Y, Yamakawa H, Shinkai Y, Ishii I, Kumagai Y. Repression of mercury accumulation and adverse effects of methylmercury exposure is mediated by cystathionine γ-lyase to produce reactive sulfur species in mouse brain. Toxicol Lett 2020; 330:128-133. [PMID: 32413476 DOI: 10.1016/j.toxlet.2020.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 04/02/2020] [Accepted: 05/07/2020] [Indexed: 01/16/2023]
Abstract
Reactive sulfur species (RSS), such as hydropersulfides and hydropolysulfides with high nucleophilicity, contain mobilized sulfur that readily captures xenobiotic electrophiles, leading to their sulfur adducts. We have previously reported that RSS produced by cystathionine γ-lyase (CSE) captures the electrophilic metal methylmercury (MeHg) to form inert sulfur adducts, which in turn play a critical role in the protection against MeHg-induced motor impairment in mice. However, the mechanism underlying this neuroprotective effect is not fully understood. Here, we addressed this using CSE-knockout mice. The cerebellum of CSE-knockout mice was more susceptible to MeHg than that of wild type mice. Moreover, these CSE-deficient mice exhibited a higher level of mercury accumulation in the brain. However, co-treatment with sodium tetrasulfide, an RSS able to capture MeHg, leading to the formation of its sulfur adducts, blocked the increased accumulation of mercury, motor dysfunction and mortality caused by CSE deficiency. Our findings suggest that capturing MeHg by RSS in association with its sulfur adduct formation is involved in the repression of the brain distribution and deleterious effects of MeHg.
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Affiliation(s)
- Masahiro Akiyama
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Takamitsu Unoki
- Department of Basic Medical Sciences, National Institute for Minamata Disease, Minamata, Kumamoto 867-0008, Japan
| | - Eiko Yoshida
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba 278-0022, Japan
| | - Yunjie Ding
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan; Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Hiroto Yamakawa
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan; Master's Program in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Yasuhiro Shinkai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Isao Ishii
- Laboratory of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan.
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Nrf2 Activation and Its Coordination with the Protective Defense Systems in Response to Electrophilic Stress. Int J Mol Sci 2020; 21:ijms21020545. [PMID: 31952233 PMCID: PMC7013553 DOI: 10.3390/ijms21020545] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 01/11/2020] [Indexed: 12/18/2022] Open
Abstract
Molecular responses mediated by sensor proteins are important for biological defense against electrophilic stresses, such as xenobiotic electrophile exposure. NF-E2-related factor 2 (Nrf2) has an essential function as a master regulator of such cytoprotective molecular responses along with sensor protein Kelch-like ECH-associated protein 1. This review focuses on Nrf2 activation and its involvement with the protective defense systems under electrophilic stresses integrated with our recent findings that reactive sulfur species (RSS) mediate detoxification of electrophiles. The Nrf2 pathway does not function redundantly with the RSS-generating cystathionine γ-lyase pathway, and vice versa.
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Li D, Xie L, Carvan MJ, Guo L. Mitigative effects of natural and model dissolved organic matter with different functionalities on the toxicity of methylmercury in embryonic zebrafish. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 252:616-626. [PMID: 31185350 DOI: 10.1016/j.envpol.2019.05.155] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 05/27/2019] [Accepted: 05/30/2019] [Indexed: 06/09/2023]
Abstract
Dissolved organic matter (DOM) occurs ubiquitously in aquatic environments and plays an intrinsic role in altering the chemical speciation and toxicity of methylmercury (MeHg). However, interactions between MeHg and natural DOM remain poorly understood, especially at the functional group level. We report here the mitigative effects of three natural organic matter (NOM) and five model-DOM under different concentrations (0, 1, 3, 10, 30 and 100 mg-C/L) on the toxicity of MeHg in embryonic zebrafish (<4 h post-fertilization, hpf). NOM are those from the Mississippi River, Yukon River, and Suwannee River, while model-DOM include those containing thiosalicylic acid, L-glutathione, dextran, alginic acid, and humic acid. We selected a MeHg concentration (100 n-mol/L) that reduces the survival rate of embryos at 24 hpf by 18% and increases malformations at 72 and 96 hpf. In the presence of DOM, however, the malformation rates induced by MeHg can be mitigated to a different extent depending on DOM concentrations, specific functional groups, and/or specific components. Model DOM with aromatic thiols was the most effective at mitigating the effects of MeHg, followed by L-glutathione, carbohydrates, and humic acid. NOM also mitigated the toxicity of MeHg dependent on their composition and/or effective DOM components as characterized by fluorescence excitation-emission matrix techniques. Specifically, humic-like DOM components are more effective in reducing the MeHg toxicity in the embryonic zebrafish compared to protein-like components. Further studies are needed to elucidate the interactions between DOM and MeHg and the mitigative mechanisms at the molecular level.
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Affiliation(s)
- Dan Li
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI, 53204, USA; Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lingtian Xie
- SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Environmental Theoretical Chemistry, South China Normal University, Guangzhou, 510006, China
| | - Michael J Carvan
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI, 53204, USA
| | - Laodong Guo
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI, 53204, USA.
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Chauhan S, Dunlap K, Duffy LK. Effects of Methylmercury and Theaflavin Digallate on Adipokines in Mature 3T3-L1 Adipocytes. Int J Mol Sci 2019; 20:ijms20112755. [PMID: 31195622 PMCID: PMC6600166 DOI: 10.3390/ijms20112755] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 05/31/2019] [Accepted: 06/02/2019] [Indexed: 02/07/2023] Open
Abstract
Diabetes is a contributor to morbidity across the globe and is often associated with obesity, metabolic syndrome and other inflammatory diseases associated with aging. In addition to genetic and lifestyle factors, environmental factors such as metals and persistent organic pollutants may increase the severity or lower the threshold of these conditions. In cell culture, methylmercury is toxic to adipocytes and may impact adipokine secretions. In this study, we determined the effects of different concentrations of theaflavin digallate on methylmercury exposed 3T3-L1 adipocytes in cell culture. Secretions of resistin, adiponectin and lipid peroxidation product, 4-hydroxynonenal (4-HNE) were monitored using ELISA assays. Cell morphology of methylmercury and theaflavin-3,3'-digallate treated adipocytes was assessed using Lipid (Oil Red O) staining. Exposure to methylmercury increased the levels of resistin and adiponectin as well as 4-HNE when compared to the control cells. Methylmercury treated cells resulted in smaller number of adipocytes and clumped lipid droplets. These results suggest that methylmercury induces reactive oxygen species leading to development of an inflammatory response. Theaflavin-3,3'-digallate reduced the impact of methylmercury by maintaining the adipocytes morphology and secretion patterns of adiponectin, resistin and 4-hydroxynonenal. With this experimental model system other anti-inflammatory and signaling agents could be tested at the biochemical level before eventually leading to studies in animal models.
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Affiliation(s)
- Shubhangi Chauhan
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK 99775-6160, USA.
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA.
| | - Kriya Dunlap
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK 99775-6160, USA.
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA.
| | - Lawrence K Duffy
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK 99775-6160, USA.
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA.
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Akiyama M, Unoki T, Shinkai Y, Ishii I, Ida T, Akaike T, Yamamoto M, Kumagai Y. Environmental Electrophile-Mediated Toxicity in Mice Lacking Nrf2, CSE, or Both. ENVIRONMENTAL HEALTH PERSPECTIVES 2019; 127:67002. [PMID: 31166132 PMCID: PMC6794492 DOI: 10.1289/ehp4949] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 06/01/2023]
Abstract
BACKGROUND Transcription factor Nrf2 (nuclear factor-erythroid 2-related factor 2) plays a key role in detoxification of electrophiles via formation of glutathione (GSH) adducts and subsequent excretion into extracellular spaces. We found that reactive sulfur species (RSS), such as cysteine persulfides produced by cystathionine [Formula: see text] (CSE), capture environmental electrophiles through formation of sulfur adducts. However, contributions of Nrf2 and CSE to the blockage of environmental electrophile-mediated toxicity remain to be evaluated. OBJECTIVES The aim of this study was to clarify roles that CSE and Nrf2 play in the protection against various environmental electrophiles. We also wished to clarify the molecular basis of the developmental window of toxicity through investigating expression levels of Nrf2, RSS-producing enzymes, and sulfur nucleophiles during developmental stages of mice. METHODS Wild-type (WT), CSE knockout (KO), Nrf2 KO, Nrf2/CSE double KO (DKO) mice, and their primary hepatocytes were analyzed in this study. Cadmium (Cd), methylmercury (MeHg), 1,4-naphthoquinone, crotonaldehyde, and acrylamide were used. We conducted Western blotting, real-time polymerase chain reaction (PCR), 3-(4,5-dimethylthiazol-2-yl)-2,5-triphenyl tetrazolium bromide (MTT) assays, liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis, alanine transaminase (ALT) activity, histopathological analysis, and rotarod test. RESULTS Primary hepatocytes from DKO mice were significantly more sensitive to the environmental electrophiles than each single KO counterpart. Both Nrf2 and CSE single KO mice were highly susceptible to Cd and MeHg, and such sensitivity was further exacerbated in the DKO mice. Lower-level expressions of CSE and sulfur nucleophiles than those in adult mice were observed in a window of developmental stage. CONCLUSIONS Our mouse model provided new insights into the response to environmental electrophiles; while Nrf2 is recognized as a key transcription factor for detoxification of environmental electrophiles, CSE is crucial factor to repress their toxicity in a parallel mode. In addition, the sensitivity of fetuses to MeHg appears to be, at least in part, associated with the restricted production of RSS due to low-level expression of CSE. https://doi.org/10.1289/EHP4949.
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Affiliation(s)
- Masahiro Akiyama
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Takamitsu Unoki
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
- Department of Basic Medical Sciences, National Institute for Minamata Disease, Minamata, Japan
| | - Yasuhiro Shinkai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Isao Ishii
- Laboratory of Health Chemistry, Showa Pharmaceutical University, Tokyo, Japan
| | - Tomoaki Ida
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Takaaki Akaike
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Masayuki Yamamoto
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
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Takanezawa Y, Nakamura R, Hamaguchi M, Yamamoto K, Sone Y, Uraguchi S, Kiyono M. Docosahexaenoic acid enhances methylmercury-induced endoplasmic reticulum stress and cell death and eicosapentaenoic acid potentially attenuates these effects in mouse embryonic fibroblasts. Toxicol Lett 2019; 306:35-42. [PMID: 30769081 DOI: 10.1016/j.toxlet.2019.02.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/25/2019] [Accepted: 02/11/2019] [Indexed: 11/26/2022]
Abstract
Fish consumption has both the risk of methylmercury (MeHg) poisoning and the benefit of obtaining n-3 polyunsaturated fatty acids (n-3 PUFAs), particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). However, the cellular interaction between MeHg and PUFAs remains unknown. Therefore, the aim of this study was to investigate the effects of MeHg and n-3 PUFA exposure on mouse embryonic fibroblasts (MEFs). The results showed that EPA had a negligible effect on MeHg-induced cell death, whereas DHA promoted it. Thiobarbituric acid reactive substance (TBARS) concentrations in cells exposed to DHA and MeHg were higher than in those exposed to EPA and MeHg. Treatment with DHA and MeHg markedly induced the expression of endoplasmic reticulum (ER) stress (CHOP and DNAJB9) and Nrf2 target gene (p62 and HMOX-1) mRNA levels. Unexpectedly, EPA supplementation in addition to DHA and MeHg attenuated DHA- and MeHg-induced cell death and suppressed ER stress and expression of Nrf2 target genes. Our results revealed a differential impact of DHA and EPA on MeHg-induced cell death, and combined treatment with DHA and EPA along with MeHg attenuated MeHg-induced toxicity.
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Affiliation(s)
- Yasukazu Takanezawa
- Department of Public Health, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Ryosuke Nakamura
- Department of Public Health, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Miho Hamaguchi
- Department of Public Health, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Kanae Yamamoto
- Department of Public Health, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Yuka Sone
- Department of Public Health, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Shimpei Uraguchi
- Department of Public Health, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Masako Kiyono
- Department of Public Health, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
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Nogara PA, Oliveira CS, Schmitz GL, Piquini PC, Farina M, Aschner M, Rocha JBT. Methylmercury's chemistry: From the environment to the mammalian brain. Biochim Biophys Acta Gen Subj 2019; 1863:129284. [PMID: 30659885 DOI: 10.1016/j.bbagen.2019.01.006] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 12/14/2018] [Accepted: 01/09/2019] [Indexed: 02/06/2023]
Abstract
Methylmercury is a neurotoxicant that is found in fish and rice. MeHg's toxicity is mediated by blockage of -SH and -SeH groups of proteins. However, the identification of MeHg's targets is elusive. Here we focus on the chemistry of MeHg in the abiotic and biotic environment. The toxicological chemistry of MeHg is complex in metazoans, but at the atomic level it can be explained by exchange reactions of MeHg bound to -S(e)H with another free -S(e)H group (R1S(e)-HgMe + R2-S(e)H ↔ R1S(e)H + R2-S(e)-HgMe). This reaction was first studied by professor Rabenstein and here it is referred as the "Rabenstein's Reaction". The absorption, distribution, and excretion of MeHg in the environment and in the body of animals will be dictated by Rabenstein's reactions. The affinity of MeHg by thiol and selenol groups and the exchange of MeHg by Rabenstein's Reaction (which is a diffusion controlled reaction) dictates MeHg's neurotoxicity. However, it is important to emphasize that the MeHg exchange reaction velocity with different types of thiol- and selenol-containing proteins will also depend on protein-specific structural and thermodynamical factors. New experimental approaches and detailed studies about the Rabenstein's reaction between MeHg with low molecular mass thiol (LMM-SH) molecules (cysteine, GSH, acetyl-CoA, lipoate, homocysteine) with abundant high molecular mass thiol (HMM-SH) molecules (albumin, hemoglobin) and HMM-SeH (GPxs, Selenoprotein P, TrxR1-3) are needed. The study of MeHg migration from -S(e)-Hg- bonds to free -S(e)H groups (Rabenstein's Reaction) in pure chemical systems and neural cells (with special emphasis to the LMM-SH and HMM-S(e)H molecules cited above) will be critical to developing realistic constants to be used in silico models that will predict the distribution of MeHg in humans.
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Affiliation(s)
- Pablo A Nogara
- Departamento de Bioquímica e Biologia Molecular, CCNE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Cláudia S Oliveira
- Departamento de Bioquímica e Biologia Molecular, CCNE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Gabriela L Schmitz
- Departamento de Bioquímica e Biologia Molecular, CCNE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Paulo C Piquini
- Departamento de Física, CCNE, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Michael Aschner
- 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.
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29
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Liu W, Yang T, Xu Z, Xu B, Deng Y. Methyl-mercury induces apoptosis through ROS-mediated endoplasmic reticulum stress and mitochondrial apoptosis pathways activation in rat cortical neurons. Free Radic Res 2018; 53:26-44. [DOI: 10.1080/10715762.2018.1546852] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Wei Liu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
| | - Tianyao Yang
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
| | - Zhaofa Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
| | - Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
| | - Yu Deng
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
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30
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Ke T, Gonçalves FM, Gonçalves CL, Dos Santos AA, Rocha JBT, Farina M, Skalny A, Tsatsakis A, Bowman AB, Aschner M. Post-translational modifications in MeHg-induced neurotoxicity. Biochim Biophys Acta Mol Basis Dis 2018; 1865:2068-2081. [PMID: 30385410 DOI: 10.1016/j.bbadis.2018.10.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 10/16/2018] [Accepted: 10/19/2018] [Indexed: 12/29/2022]
Abstract
Mercury (Hg) exposure remains a major public health concern due to its widespread distribution in the environment. Organic mercurials, such as MeHg, have been extensively investigated especially because of their congenital effects. In this context, studies on the molecular mechanism of MeHg-induced neurotoxicity are pivotal to the understanding of its toxic effects and the development of preventive measures. Post-translational modifications (PTMs) of proteins, such as phosphorylation, ubiquitination, and acetylation are essential for the proper function of proteins and play important roles in the regulation of cellular homeostasis. The rapid and transient nature of many PTMs allows efficient signal transduction in response to stress. This review summarizes the current knowledge of PTMs in MeHg-induced neurotoxicity, including the most commonly PTMs, as well as PTMs induced by oxidative stress and PTMs of antioxidant proteins. Though PTMs represent an important molecular mechanism for maintaining cellular homeostasis and are involved in the neurotoxic effects of MeHg, we are far from understanding the complete picture on their role, and further research is warranted to increase our knowledge of PTMs in MeHg-induced neurotoxicity.
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Affiliation(s)
- Tao Ke
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States.
| | - Filipe Marques Gonçalves
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | - Cinara Ludvig Gonçalves
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | | | - João B T Rocha
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, 97105900 Santa Maria, RS, Brazil
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040900 Florianópolis, SC, Brazil
| | - Anatoly Skalny
- Yaroslavl State University, Sovetskaya St., 14, Yaroslavl 150000, Russia; Peoples' Friendship University of Russia (RUDN University), Miklukho-Maklaya St., 6, Moscow 105064, Russia; Orenburg State University, Pobedy Ave., 13, Orenburg 460352, Russia
| | - Aristidis Tsatsakis
- Center of Toxicology Science & Research, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN, United States.
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States.
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31
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Unoki T, Akiyama M, Kumagai Y, Gonçalves FM, Farina M, da Rocha JBT, Aschner M. Molecular Pathways Associated With Methylmercury-Induced Nrf2 Modulation. Front Genet 2018; 9:373. [PMID: 30271424 PMCID: PMC6146031 DOI: 10.3389/fgene.2018.00373] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 08/23/2018] [Indexed: 12/19/2022] Open
Abstract
Methylmercury (MeHg) is a potent neurotoxin that affects particularly the developing brain. Since MeHg is a potent electrophilic agent, a wide range of intracellular effects occur in response to its exposure. Yet, the molecular mechanisms associated with MeHg-induced cell toxicity have yet to be fully understood. Activation of cell defense mechanisms in response to metal exposure, including the up-regulation of Nrf2- (nuclear factor erythroid 2-related factor 2)-related genes has been previously shown. Nrf2 is a key regulator of cellular defenses against oxidative, electrophilic and environmental stress, regulating the expression of antioxidant proteins, phase-II xenobiotic detoxifying enzymes as well phase-III xenobiotic transporters. Analogous to other electrophiles, MeHg activates Nrf2 through modification of its repressor Keap1 (Kelch-like ECH-associated protein 1). However, recent findings have also revealed that Keap1-independent signal pathways might contribute to MeHg-induced Nrf2 activation and cytoprotective responses against MeHg exposure. These include, Akt phosphorylation (Akt/GSK-3β/Fyn-mediated Nrf2 activation pathway), activation of the PTEN/Akt/CREB pathway and MAPK-induced autophagy and p62 expression. In this review, we summarize the state-of-the-art knowledge regarding Nrf2 up-regulation in response to MeHg exposure, highlighting the modulation of signaling pathways related to Nrf2 activation. The study of these mechanisms is important in evaluating MeHg toxicity in humans, and can contribute to the identification of the molecular mechanisms associated with MeHg exposure.
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Affiliation(s)
- Takamitsu Unoki
- Department of Basic Medical Sciences, National Institute for Minamata Diseasexy3Minamata, Japan
| | - Masahiro Akiyama
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Filipe Marques Gonçalves
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Marcelo Farina
- Department of Biochemistry, Federal University of Santa Catarina, Florianópolis, Brazil
| | | | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
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Antunes Dos Santos A, Ferrer B, Marques Gonçalves F, Tsatsakis AM, Renieri EA, Skalny AV, Farina M, Rocha JBT, Aschner M. Oxidative Stress in Methylmercury-Induced Cell Toxicity. TOXICS 2018; 6:toxics6030047. [PMID: 30096882 PMCID: PMC6161175 DOI: 10.3390/toxics6030047] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/03/2018] [Accepted: 08/07/2018] [Indexed: 02/06/2023]
Abstract
Methylmercury (MeHg) is a hazardous environmental pollutant, which elicits significant toxicity in humans. The accumulation of MeHg through the daily consumption of large predatory fish poses potential health risks, and the central nervous system (CNS) is the primary target of toxicity. Despite well-described neurobehavioral effects (i.e., motor impairment), the mechanisms of MeHg-induced toxicity are not completely understood. However, several lines of evidence point out the oxidative stress as an important molecular mechanism in MeHg-induced intoxication. Indeed, MeHg is a soft electrophile that preferentially interacts with nucleophilic groups (mainly thiols and selenols) from proteins and low-molecular-weight molecules. Such interaction contributes to the occurrence of oxidative stress, which can produce damage by several interacting mechanisms, impairing the function of various molecules (i.e., proteins, lipids, and nucleic acids), potentially resulting in modulation of different cellular signal transduction pathways. This review summarizes the general aspects regarding the interaction between MeHg with regulators of the antioxidant response system that are rich in thiol and selenol groups such as glutathione (GSH), and the selenoenzymes thioredoxin reductase (TrxR) and glutathione peroxidase (Gpx). A particular attention is directed towards the role of the PI3K/Akt signaling pathway and the nuclear transcription factor NF-E2-related factor 2 (Nrf2) in MeHg-induced redox imbalance.
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Affiliation(s)
| | - Beatriz Ferrer
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Filipe Marques Gonçalves
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Aristides M Tsatsakis
- Laboratory of Toxicology, Medical School, University of Crete, 71003 Heraklion, Greece.
| | - Elisavet A Renieri
- Laboratory of Toxicology, Medical School, University of Crete, 71003 Heraklion, Greece.
| | - Anatoly V Skalny
- Department of Medical Elementology, Peoples' Friendship University of Russia (RUDN University), Moscow 150000, Russia.
- Laboratory of Biotechnology and Applied Bioelementology, Yaroslavl State University, Yaroslavl 150014, Russia.
- All-Russian Research Institute of Medicinal and Aromatic Plants (VILAR), Moscow 150000, Russia.
| | - Marcelo Farina
- Department of Biochemistry, Federal University of Santa Catarina, Florianopolis 88040-900, Santa Catarina, Brazil.
| | - João B T Rocha
- Department of Biochemistry, Federal University of Santa Maria, Santa Maria 97105-900, Rio Grande do Sul, Brazil.
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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C. elegans as a model in developmental neurotoxicology. Toxicol Appl Pharmacol 2018; 354:126-135. [PMID: 29550512 DOI: 10.1016/j.taap.2018.03.016] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 02/28/2018] [Accepted: 03/12/2018] [Indexed: 12/22/2022]
Abstract
Due to many advantages Caenorhabditis elegans (C. elegans) has become a preferred model of choice in many fields, including neurodevelopmental toxicity studies. This review discusses the benefits of using C. elegans as an alternative to mammalian systems and gives examples of the uses of the nematode in evaluating the effects of major known neurodevelopmental toxins, including manganese, mercury, lead, fluoride, arsenic and organophosphorus pesticides. Reviewed data indicates numerous similarities with mammals in response to these toxins. Thus, C. elegans studies have the potential to predict possible effects of developmental neurotoxicants in higher animals, and may be used to identify new molecular pathways behind neurodevelopmental disruptions, as well as new toxicants.
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Gombeau K, de Oliveira RB, Sarrazin SLF, Mourão RHV, Bourdineaud JP. Protective Effects of Plathymenia reticulata and Connarus favosus Aqueous Extracts against Cadmium- and Mercury-Induced Toxicities. Toxicol Res 2018; 35:25-35. [PMID: 30766655 PMCID: PMC6354948 DOI: 10.5487/tr.2019.35.1.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 06/21/2018] [Accepted: 07/20/2018] [Indexed: 12/11/2022] Open
Abstract
The extracts of Plathymenia reticulata and Connarus favosus are widely used in the folk medicine. The potential protective effects of these extracts have been evaluated against cadmium in the yeast Saccharomyces cerevisiae, and against mercurial contamination in zebrafish Danio rerio. In yeast, both extracts efficiently protected the Δycf1 mutant strain exposed to cadmium chloride restoring the growth, the expression of stress-response genes and decreasing the level of oxidative stress. In zebrafish, the supplementation of methylmercury-contaminated diet with both plant extracts similarly protected fish through the suppression of the methylmercury-induced lipid peroxidation, decrease of acetylcholinesterase activity, and restoring the expression levels of stress-response genes. This study particularly demonstrates the protective potential of both aqueous extracts against methylmercury, and could represent an interesting alternative for the Amazonian fish-eating communities to cope with the impact of chronic exposure to contaminated diets.
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Affiliation(s)
- Kewin Gombeau
- University of Bordeaux, CNRS, UMR 5805, EPOC, Arcachon Marine Station, 33120 Arcachon, France
| | - Ricardo Bezerra de Oliveira
- Federal University of Western Pará - UFOPA, PPGRNA, LABBEX, Tapajós Campus, Rua Vera Paz s/n, Bairro Salé, CEP, 68040-050, Caranazal, 88040-060 Santarém, Pará, Brazil
| | - Sandra Layse Ferreira Sarrazin
- Federal University of Western Pará - UFOPA, PPGRNA, LABBEX, Tapajós Campus, Rua Vera Paz s/n, Bairro Salé, CEP, 68040-050, Caranazal, 88040-060 Santarém, Pará, Brazil
| | - Rosa Helena Veras Mourão
- Federal University of Western Pará - UFOPA, PPGRNA, LABBEX, Tapajós Campus, Rua Vera Paz s/n, Bairro Salé, CEP, 68040-050, Caranazal, 88040-060 Santarém, Pará, Brazil
| | - Jean-Paul Bourdineaud
- University of Bordeaux, CNRS, UMR 5805, EPOC, Arcachon Marine Station, 33120 Arcachon, France
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Chen H, Tang X, Zhou B, Zhou Z, Xu N, Wang Y. A ROS-mediated mitochondrial pathway and Nrf2 pathway activation are involved in BDE-47 induced apoptosis in Neuro-2a cells. CHEMOSPHERE 2017; 184:679-686. [PMID: 28628905 DOI: 10.1016/j.chemosphere.2017.06.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/27/2017] [Accepted: 06/03/2017] [Indexed: 05/23/2023]
Abstract
Our previous study showed that 2,2'-,4,4'-tetrabromodiphenyl ether (BDE-47) is cytotoxic and induces apoptosis in Neuro-2a cells. In the present study, we aimed to investigate whether nuclear factor (erythroid-derived 2)-like 2 (Nrf2), an antioxidant transcriptional regulator of oxidative stress and apoptosis, is involved in this process. The results of toxicological experiments showed that BDE-47 decreased the cellular mitochondrial membrane potential (MMP) and increased cytochrome c release to the cytoplasm, followed by an increase in intracellular caspase-9 and caspase-3 activity, suggesting that a mitochondrial pathway was involved in the apoptotic process. Intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) contents as well as the oxidized/reduced glutathione (GSSG/GSH) ratio were elevated simultaneously in a concentration-dependent manner, indicating that BDE-47 induced oxidative stress. The ROS scavenger N-acetyl-l-cysteine (NAC) not only alleviated the oxidative stress but also blocked apoptosis and the decrease in MMP induced by BDE-47, indicating that the overproduction of ROS participates in a mitochondria-mediated apoptotic pathway. Moreover, BDE-47 stimulated the transcriptional induction of the Nrf-2 gene and induced mRNA expression of the main antioxidant response genes in the Nrf-2 pathway, including heme oxygenase 1 (HO-1), NAD(P)H/quinone oxidoreductase-1 (NQO1), glutamate-cysteine ligase modifier (GCLM) and glutathione peroxidase (GPX). Additionally, NAC and the p38 mitogen activated protein kinase (MAPK) signaling pathway inhibitor SB 203580 greatly reduced Nrf2 and HO-1 induction. We hypothesized that the ROS mediated mitochondrial pathway is involved in the BDE-47-induced apoptosis in Neuro-2a cells and that the Nrf2 pathway helps protect Neuro-2a cells from BDE-47-induced apoptosis.
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Affiliation(s)
- Hongmei Chen
- Department of Marine Ecology, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China; Key Laboratory of Xinjiang Endemic Phytomedicine Resources, Ministry of Education, Pharmacology Department, School of Pharmacy, Shihezi University, Shihezi 832002, China.
| | - Xuexi Tang
- Department of Marine Ecology, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Bin Zhou
- Department of Marine Ecology, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Zhongyuan Zhou
- Department of Marine Ecology, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Ningning Xu
- Department of Marine Ecology, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - You Wang
- Department of Marine Ecology, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
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Yang T, Xu Z, Liu W, Feng S, Li H, Guo M, Deng Y, Xu B. Alpha-lipoic acid reduces methylmercury-induced neuronal injury in rat cerebral cortex via antioxidation pathways. ENVIRONMENTAL TOXICOLOGY 2017; 32:931-943. [PMID: 27298056 DOI: 10.1002/tox.22294] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 05/18/2016] [Accepted: 05/22/2016] [Indexed: 06/06/2023]
Abstract
Methylmercury (MeHg), an extremely dangerous environmental pollutant, accumulating preferentially in central nervous system, causes a series of cytotoxic effects. The present study explored the mechanisms which contribute to MeHg-induced neurotoxicity focusing on the oxidative stress in rat cerebral cortex. In addition, the protective effects of alpha-lipoic acid (LA), a potent antioxidant on MeHg-mediated neuronal injury, was also investigated in current study. A MeHg poisoning model was established as 64 rats randomly divided into 4 groups of which saline control group, MeHg-treated groups (4 and 12 μmol kg-1 ), and LA pretreatment (35 μmol kg-1 ) group, respectively. After administration of 12 μmol kg-1 MeHg for 4 weeks, it was found that obvious pathological changes and apoptosis in neuronal cells. Meanwhile, total Hg levels elevated significantly, superoxide dismutase (SOD) and gluthathione peroxidase (GSH-Px) activities were inhibited, and ROS formation elevated, which might be critical to aggravate oxidative stress in cerebral cortex. In addition, NF-E2-related factor 2 (Nrf2) pathways were activated, as heme oxygenase-1 (HO-1) and γ-glutamylcysteine synthetase heavy subunit (γ-GCSh) expressions were up-regulated obviously by MeHg exposure. Moreover, activities of Na+ -K+ -ATPase and Ca2+ -ATPase were inhibited, leading to intracellular calcium (Ca2+ ) overload. LA pre-treatment partially reduced MeHg neurotoxic effects via anti-oxidation pathways. In conclusion, these findings clearly indicated that MeHg aggravated oxidative stress and Ca2+ overload in cerebral cortex. LA possesses the ability to prevent MeHg neurotoxicity through its anti-oxidative properties. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 931-943, 2017.
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Affiliation(s)
- Tianyao Yang
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning Province, 110122, People's Republic of China
| | - Zhaofa Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning Province, 110122, People's Republic of China
| | - Wei Liu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning Province, 110122, People's Republic of China
| | - Shu Feng
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning Province, 110122, People's Republic of China
| | - Hongpeng Li
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning Province, 110122, People's Republic of China
| | - Meixin Guo
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning Province, 110122, People's Republic of China
| | - Yu Deng
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning Province, 110122, People's Republic of China
| | - Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning Province, 110122, People's Republic of 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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38
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Toyama T, Abiko Y, Katayama Y, Kaji T, Kumagai Y. S-Mercuration of ubiquitin carboxyl-terminal hydrolase L1 through Cys152 by methylmercury causes inhibition of its catalytic activity and reduction of monoubiquitin levels in SH-SY5Y cells. J Toxicol Sci 2016; 40:887-93. [PMID: 26558469 DOI: 10.2131/jts.40.887] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Methylmercury (MeHg) is an environmental electrophile that covalently modifies cellular proteins. In this study, we identified proteins that undergo S-mercuration by MeHg. By combining two-dimensional SDS-PAGE, atomic absorption spectrometry and ultra performance liquid chromatography mass spectrometry (UPLC/MS/MS), we revealed that ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) is a target for S-mercuration in human neuroblastoma SH-SY5Y cells exposed to MeHg (1 µM, 9 hr). The modification site of UCH-L1 by MeHg was Cys152, as determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. MeHg was shown to inhibit the catalytic activity of recombinant human UCH-L1 in a concentration-dependent manner. Knockdown of UCH-L1 indicated that this enzyme plays a critical role in regulating mono-ubiquitin (monoUb) levels in SH-SY5Y cells and exposure of SH-SY5Y cells to MeHg caused a reduction in the level of monoUb in these cells. These observations suggest that UCH-L1 readily undergoes S-mercuration by MeHg through Cys152 and this covalent modification inhibits UCH-L1, leading to the potential disruption of the maintenance of cellular monoUb levels.
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Memantine, a Low-Affinity NMDA Receptor Antagonist, Protects against Methylmercury-Induced Cytotoxicity of Rat Primary Cultured Cortical Neurons, Involvement of Ca2+ Dyshomeostasis Antagonism, and Indirect Antioxidation Effects. Mol Neurobiol 2016; 54:5034-5050. [DOI: 10.1007/s12035-016-0020-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 08/01/2016] [Indexed: 01/20/2023]
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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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41
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Fujie T, Murakami M, Yoshida E, Tachinami T, Shinkai Y, Fujiwara Y, Yamamoto C, Kumagai Y, Naka H, Kaji T. Copper diethyldithiocarbamate as an activator of Nrf2 in cultured vascular endothelial cells. J Biol Inorg Chem 2016; 21:263-73. [PMID: 26825804 PMCID: PMC4801994 DOI: 10.1007/s00775-016-1337-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 01/08/2016] [Indexed: 12/21/2022]
Abstract
The interest in organic-inorganic hybrid molecules as molecular probes for biological systems has been growing rapidly. Such hybrid molecules exhibit unique biological activities. Herein, copper(II) bis(diethyldithiocarbamate) (Cu10) was found to activate the transcription factor NF-E2-related factor 2 (Nrf2), which is responsible for regulating antioxidant and phase II xenobiotic enzymes, in vascular endothelial cells. The copper complex rapidly accumulated within cells and induced nuclear translocation of Nrf2, leading to upregulation of the expression of downstream proteins without cytotoxic effects. However, while copper bis(2-hydroxyethyl)dithiocarbamate activated Nrf2, copper ion, diethyldithiocarbamate ligand with or without zinc or iron failed to exhibit this activity. Intracellular accumulation of Cu10 was higher than that of Cu(II) and Cu(I). While the accumulation of copper(II) bis(dimethyldithiocarbamate) was reduced by small interfering RNA (siRNA)-mediated knockdown of the copper transporter CTR1, the knockdown did not affect Cu10 accumulation, indicating that Cu10 rapidly enters vascular endothelial cells via CTR1-independent mechanisms. In addition, copper and iron complexes with other ligands tested could not activate Nrf2, suggesting that the intramolecular interaction between copper and dithiocarbamate ligand is important for the activation of the transcription factor. Cu10 induced the expression of heme oxygenase-1, NAD(P)H quinone oxidoreductase 1, and γ-glutamylcysteine synthetase, downstream proteins of Nrf2. It was suggested that Cu10-induced activation of Nrf2 was due to proteasome inhibition as well as binding to Kelch-like ECH-associated protein 1. Since the effects of Cu10 on vascular endothelial cells are unique and diverse, the copper complex may be a good molecular probe to analyze the functions of the cells.
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Affiliation(s)
- Tomoya Fujie
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, 278-8510, Japan
| | - Masaki Murakami
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, 278-8510, Japan
| | - Eiko Yoshida
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, 278-8510, Japan
| | - Tadashi Tachinami
- Graduate School of Science and Research Center for Materials Science, Nagoya University, Chikusa, Nagoya, 464-8602, Japan
| | - Yasuhiro Shinkai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan
| | - Yasuyuki Fujiwara
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, 192-0392, Japan
| | - Chika Yamamoto
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, 274-8510, Japan
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan
| | - Hiroshi Naka
- Graduate School of Science and Research Center for Materials Science, Nagoya University, Chikusa, Nagoya, 464-8602, Japan.
| | - Toshiyuki Kaji
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, 278-8510, Japan.
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Nishida M, Kumagai Y, Ihara H, Fujii S, Motohashi H, Akaike T. Redox signaling regulated by electrophiles and reactive sulfur species. J Clin Biochem Nutr 2016; 58:91-8. [PMID: 27013774 PMCID: PMC4788399 DOI: 10.3164/jcbn.15-111] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 09/10/2015] [Indexed: 01/23/2023] Open
Abstract
Redox signaling is a key modulator of oxidative stress induced by nonspecific insults of biological molecules generated by reactive oxygen species. Current redox biology is revisiting the traditional concept of oxidative stress, such that toxic effects of reactive oxygen species are protected by diverse antioxidant systems upregulated by oxidative stress responses that are physiologically mediated by redox-dependent cell signaling pathways. Redox signaling is thus precisely regulated by endogenous electrophilic substances that are generated from reactive oxygen species and nitric oxide and its derivative reactive species during stress responses. Among electrophiles formed endogenously, 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP) has unique cell signaling functions, and pathways for its biosynthesis, signaling mechanism, and metabolism in cells have been clarified. Reactive sulfur species such as cysteine hydropersulfides that are abundant in cells are likely involved in 8-nitro-cGMP metabolism. These new aspects of redox biology may stimulate innovative and multidisciplinary research in cell and stem cell biology; infectious diseases, cancer, metabolic syndrome, ageing, and neurodegenerative diseases; and other oxidative stress-related disorders. This review focuses on the most recent progress in the biosynthesis, cell signaling, and metabolism of 8-nitro-cGMP, which is a likely target for drug development and lead to discovery of novel therapeutics for many diseases.
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Affiliation(s)
- Motohiro Nishida
- Division of Cardiocirculatory Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan; Department of Translational Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan; PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi 332-0012, Japan
| | - Yoshito Kumagai
- Environmental Biology Section, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
| | - Hideshi Ihara
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan
| | - Shigemoto Fujii
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Hozumi Motohashi
- Department of Gene Expression Regulation, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Takaaki Akaike
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
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43
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Shinkai Y, Kimura T, Itagaki A, Yamamoto C, Taguchi K, Yamamoto M, Kumagai Y, Kaji T. Partial contribution of the Keap1-Nrf2 system to cadmium-mediated metallothionein expression in vascular endothelial cells. Toxicol Appl Pharmacol 2016; 295:37-46. [PMID: 26827822 DOI: 10.1016/j.taap.2016.01.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/25/2016] [Accepted: 01/27/2016] [Indexed: 12/26/2022]
Abstract
Cadmium is an environmental electrophile that modifies protein reactive thiols such as Kelch-like ECH-associated protein 1 (Keap1), a negative regulator of nuclear factor-erythroid 2-related factor 2 (Nrf2). In the present study, we investigated a role of the Keap1-Nrf2 system in cellular response to cadmium in vascular endothelial cells. Exposure of bovine aortic endothelial cells to cadmium resulted in modification of Keap1 and Nrf2 activation, thereby up-regulating not only its typical downstream proteins but also metallothionein-1/2. Experiments with siRNA-mediated knockdown of Nrf2 or Keap1 supported participation of the Keap1-Nrf2 system in the modulation of metallothionein-1/2 expression. Furthermore, chromatin immunoprecipitation assay showed that Nrf2 was recruited to the antioxidant response element of the promoter region of the bovine metallothionein-2 gene in the presence of cadmium. These results suggest that the transcription factor Nrf2 plays, at least in part, a role in the changes in metallothionein expression mediated by exposure to cadmium.
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Affiliation(s)
- Yasuhiro Shinkai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Tomoki Kimura
- Faculty of Science and Engineering, Setsunan University, 17-8 Ikedanaka-machi, Neyagawa, Osaka 572-8508, Japan
| | - Ayaka Itagaki
- Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3 Kanagawa, Kanazawa, 920-1181, Ishikawa, Japan
| | - Chika Yamamoto
- Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3 Kanagawa, Kanazawa, 920-1181, Ishikawa, Japan; Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
| | - Keiko Taguchi
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-cho, Aoba-ku, Sendai 980-8575, Japan
| | - Masayuki Yamamoto
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-cho, Aoba-ku, Sendai 980-8575, Japan
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Toshiyuki Kaji
- Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3 Kanagawa, Kanazawa, 920-1181, Ishikawa, Japan; Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
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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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Protective actions of 17β-estradiol and progesterone on oxidative neuronal injury induced by organometallic compounds. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:343706. [PMID: 25815107 PMCID: PMC4359856 DOI: 10.1155/2015/343706] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Accepted: 02/06/2015] [Indexed: 01/10/2023]
Abstract
Steroid hormones synthesized in and secreted from peripheral endocrine glands pass through the blood-brain barrier and play a role in the central nervous system. In addition, the brain possesses an inherent endocrine system and synthesizes steroid hormones known as neurosteroids. Increasing evidence shows that neuroactive steroids protect the central nervous system from various harmful stimuli. Reports show that the neuroprotective actions of steroid hormones attenuate oxidative stress. In this review, we summarize the antioxidative effects of neuroactive steroids, especially 17β-estradiol and progesterone, on neuronal injury in the central nervous system under various pathological conditions, and then describe our recent findings concerning the neuroprotective actions of 17β-estradiol and progesterone on oxidative neuronal injury induced by organometallic compounds, tributyltin, and methylmercury.
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Abiko Y, Luong NC, Kumagai Y. A Biotin-PEAC 5-maleimide labeling assay to detect electrophiles. J Toxicol Sci 2015; 40:405-11. [DOI: 10.2131/jts.40.405] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Yumi Abiko
- Faculty of Medicine, University of Tsukuba
| | - Nho Cong Luong
- Master’s Program of Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Yoshito Kumagai
- Master’s Program of Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba
- Faculty of Medicine, University of Tsukuba
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47
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Makino K, Okuda K, Sugino E, Nishiya T, Toyama T, Iwawaki T, Fujimura M, Kumagai Y, Uehara T. Correlation Between Attenuation of Protein Disulfide Isomerase Activity Through S-Mercuration and Neurotoxicity Induced by Methylmercury. Neurotox Res 2014; 27:99-105. [DOI: 10.1007/s12640-014-9494-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/22/2014] [Accepted: 09/29/2014] [Indexed: 10/24/2022]
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48
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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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Bisen-Hersh EB, Farina M, Barbosa F, Rocha JBT, Aschner M. Behavioral effects of developmental methylmercury drinking water exposure in rodents. J Trace Elem Med Biol 2014; 28:117-124. [PMID: 24210169 PMCID: PMC3979511 DOI: 10.1016/j.jtemb.2013.09.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/19/2013] [Accepted: 09/19/2013] [Indexed: 10/26/2022]
Abstract
Early methylmercury (MeHg) exposure can have long-lasting consequences likely arising from impaired developmental processes, the outcome of which has been exposed in several longitudinal studies of affected populations. Given the large number of newborns at an increased risk of learning disabilities associated with in utero MeHg exposure, it is important to study neurobehavioral alterations using ecologically valid and physiologically relevant models. This review highlights the benefits of using the MeHg drinking water exposure paradigm and outlines behavioral outcomes arising from this procedure in rodents. Combination treatments that exacerbate or ameliorate MeHg-induced effects, and possible molecular mechanisms underlying behavioral impairment are also discussed.
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Affiliation(s)
- Emily B Bisen-Hersh
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Fernando Barbosa
- Department of Clinical, Toxicological and Bromatological Analyses, Faculty of Pharmaceutical Sciences of Ribeirão Preto, São Paulo, Brazil
| | - Joao B T Rocha
- Departamento de Química, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Michael Aschner
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pharmacology, The Kennedy Center for Research on Human Development, and The Center for Molecular Toxicology, Vanderbilt University Medical Center, Nashville, TN, USA
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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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