1
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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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Li B, Jin X, Chan HM. Effects of low doses of methylmercury (MeHg) exposure on definitive endoderm cell differentiation in human embryonic stem cells. Arch Toxicol 2023; 97:2625-2641. [PMID: 37612375 PMCID: PMC10475006 DOI: 10.1007/s00204-023-03580-7] [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: 07/13/2023] [Accepted: 08/03/2023] [Indexed: 08/25/2023]
Abstract
Fetal development is one of the most sensitive windows to methylmercury (MeHg) toxicity. Laboratory and epidemiological studies have shown a dose-response relationship between fetal MeHg exposure and neuro performance in different life stages from infants to adults. In addition, MeHg exposure has been reported to be associated with disorders in endoderm-derived organs, such as morphological changes in liver cells and pancreatic cell dysfunctions. However, the mechanisms of the effects of MeHg on non-neuronal organs or systems, especially during the early development of endoderm-derived organs, remain unclear. Here we determined the effects of low concentrations of MeHg exposure during the differentiation of definitive endoderm (DE) cells from human embryonic stem cells (hESCs). hESCs were exposed to MeHg (0, 10, 100, and 200 nM) that covers the range of Hg concentrations typically found in human maternal blood during DE cell induction. Transcriptomic analysis showed that sub-lethal doses of MeHg exposure could alter global gene expression patterns during hESC to DE cell differentiation, leading to increased expression of endodermal genes/proteins and the over-promotion of endodermal fate, mainly through disrupting calcium homeostasis and generating ROS. Bioinformatic analysis results suggested that MeHg exerts its developmental toxicity mainly by disrupting ribosome biogenesis during early cell lineage differentiation. This disruption could lead to aberrant growth or dysfunctions of the developing endoderm-derived organs, and it may be the underlying mechanism for the observed congenital diseases later in life. Based on the results, we proposed an adverse outcome pathway for the effects of MeHg exposure during human embryonic stem cells to definitive endoderm differentiation.
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Affiliation(s)
- Bai Li
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada
| | - Xiaolei Jin
- Regulatory Toxicology Research Division, Bureau of Chemical Safety, Food Directorate, HPFB, Health Canada, 251 Sir Frederick Banting Driveway, Ottawa, ON, K1A 0K9, Canada.
| | - Hing Man Chan
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada.
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3
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The Modulatory Role of sti-1 in Methylmercury-Induced Toxicity in Caenorhabditis elegans. Neurotox Res 2022; 40:837-846. [PMID: 35471723 DOI: 10.1007/s12640-022-00515-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/14/2022] [Accepted: 04/19/2022] [Indexed: 10/18/2022]
Abstract
Human exposure to the neurotoxin methylmercury (MeHg) poses a significant health risk to the development of the nervous system. The mechanisms of MeHg-induced neurotoxicity are associated with the disruption of cellular homeostasis, and include oxidative stress, loss of calcium homeostasis, and impaired protein quality control. The stress inducible protein 1 (STI-1) is involved in the regulation of protein quality control by acting as a protein cochaperone to maintain optimal protein unfolding and refolding. Here, we utilized the Caenorhabditis elegans (C. elegans) model of MeHg toxicity to characterize the role of the sti-1 gene in MeHg-induced toxicity. We showed that lifespan and developmental milestone timings were significantly altered in sti-1 knockout (KO) animals with MeHg exposure. However, knocking down sti-1 by RNAi did not result in an analogous effect for lifespan, but did still sensitize to delays in developmental milestone progression by acute MeHg, suggesting that insufficiency of sti-1 does not recapitulate all phenotypes of the null mutation. Furthermore, inhibition of ATP levels by MeHg exposure was modulated by sti-1. Considering that the skn-1/gst-4 pathway is highly involved in metal's toxicity, such pathway was also explored in our model. We showed that sti-1 mutant worms exhibited impaired capacity to upregulate the antioxidant genes skn-1/gst-4, highlighting a central role of sti-1 in modulating antioxidant response. Lastly, we showed that loss-of-function mutation in the rrf-3 gene, which encodes a putative RNA-directed RNA polymerase, has significant effect in altering MeHg-induced toxicity by potentiating the animal's detoxification system. Altogether, our novel data show an indispensable role of protein quality control in the defense against MeHg toxicity.
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4
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Glazer L, Brennan CH. Developmental Exposure to Low Concentrations of Methylmercury Causes Increase in Anxiety-Related Behaviour and Locomotor Impairments in Zebrafish. Int J Mol Sci 2021; 22:10961. [PMID: 34681620 PMCID: PMC8535691 DOI: 10.3390/ijms222010961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/22/2021] [Accepted: 09/29/2021] [Indexed: 11/17/2022] Open
Abstract
Methylmercury (MeHg) is a ubiquitous pollutant shown to cause developmental neurotoxicity, even at low levels. However, there is still a large gap in our understanding of the mechanisms linking early-life exposure to life-long behavioural impairments. Our aim was to characterise the short- and long-term effects of developmental exposure to low doses of MeHg on anxiety-related behaviours in zebrafish, and to test the involvement of neurological pathways related to stress-response. Zebrafish embryos were exposed to sub-acute doses of MeHg (0, 5, 10, 15, 30 nM) throughout embryo-development, and tested for anxiety-related behaviours and locomotor activity at larval (light/dark locomotor activity) and adult (novel tank and tap assays) life-stages. Exposure to all doses of MeHg caused increased anxiety-related responses; heightened response to the transition from light to dark in larvae, and a stronger dive response in adults. In addition, impairment in locomotor activity was observed in the higher doses in both larvae and adults. Finally, the expressions of several neural stress-response genes from the HPI-axis and dopaminergic system were found to be disrupted in both life-stages. Our results provide important insights into dose-dependent differences in exposure outcomes, the development of delayed effects over the life-time of exposed individuals and the potential mechanisms underlying these effects.
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Affiliation(s)
- Lilah Glazer
- Nanchang Joint Programme, School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - Caroline H. Brennan
- Department of Biological and Experimental Psychology, School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK;
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5
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Environmentally relevant developmental methylmercury exposures alter neuronal differentiation in a human-induced pluripotent stem cell model. Food Chem Toxicol 2021; 152:112178. [PMID: 33831500 DOI: 10.1016/j.fct.2021.112178] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/15/2021] [Accepted: 03/30/2021] [Indexed: 12/14/2022]
Abstract
Developmental methylmercury (MeHg) exposure selectively targets the cerebral and cerebellar cortices, as seen by disruption of cytoarchitecture and glutamatergic (GLUergic) neuron hypoplasia. To begin to understand the mechanisms of this loss of GLUergic neurons, we aimed to develop a model of developmental MeHg neurotoxicity in human-induced pluripotent stem cells differentiating into cortical GLUergic neurons. Three dosing paradigms at 0.1 μM and 1.0 μM MeHg, which span different stages of neurodevelopment and reflect toxicologically relevant accumulation levels seen in human studies and mammalian models, were established. With these exposure paradigms, no changes were seen in commonly studied endpoints of MeHg toxicity, including viability, proliferation, and glutathione levels. However, MeHg exposure induced changes in mitochondrial respiration and glycolysis and in markers of neuronal differentiation. Our novel data suggests that GLUergic neuron hypoplasia seen with MeHg toxicity may be due to the partial inhibition of neuronal differentiation, given the increased expression of the early dorsal forebrain marker FOXG1 and corresponding decrease in expression on neuronal markers MAP2 and DCX and the deep layer cortical neuronal marker TBR1. Future studies should examine the persistent and latent functional effects of this MeHg-induced disruption of neuronal differentiation as well as transcriptomic and metabolomic alterations that may mediate MeHg toxicity.
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6
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Methylmercury, oxidative stress, and neurodegeneration. Toxicology 2021. [DOI: 10.1016/b978-0-12-819092-0.00015-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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7
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Nejad SM, Hodjat M, Mousavi SA, Baeeri M, Rezvanfar MA, Rahimifard M, Sabuncuoglu S, Abdollahi M. Alteration of gene expression profile in mouse embryonic stem cells and neural differentiation deficits by ethephon. Hum Exp Toxicol 2020; 39:1518-1527. [PMID: 32519556 DOI: 10.1177/0960327120930255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ethephon, a member of the organophosphorus compounds, is one of the most widely used plant growth regulators for artificial ripening. Although million pounds of this chemical is being used annually, the knowledge regarding its molecular toxicity is yet not sufficient. The purpose of this study was to evaluate the potential developmental toxicity of ethephon using embryonic stem cell model. The mouse embryonic stem cells (mESCs) were exposed to various concentrations of ethephon and the viability, cell cycle alteration and changes in the gene expression profile were evaluated using high-throughput RNA sequencing. Further, the effect of ethephon on neural differentiation potential was examined. The results showed that ethephon at noncytotoxic doses induced cell cycle arrest in mESCs. Gene ontology enrichment analysis showed that terms related to cell fate and organismal development, including neuron fate commitment, embryo development and cardiac cell differentiation, were markedly enriched in ethephon-treated cells. Neural induction of mESCs in the presence of ethephon was inhibited and the expression of neural genes was decreased in differentiated cells. Results obtained from this work clearly demonstrate that ethephon affects the gene expression profile of undifferentiated mESCs and prevents neural differentiation. Therefore, more caution against the frequent application of ethephon is advised.
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Affiliation(s)
- S Mohammadi Nejad
- Toxicology and Diseases Group, Pharmaceutical Sciences Research Center (PSRC), The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Pharmaceutical Toxicology, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey
| | - M Hodjat
- Toxicology and Diseases Group, Pharmaceutical Sciences Research Center (PSRC), The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran
| | - S A Mousavi
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran.,Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - M Baeeri
- Toxicology and Diseases Group, Pharmaceutical Sciences Research Center (PSRC), The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran
| | - M A Rezvanfar
- Toxicology and Diseases Group, Pharmaceutical Sciences Research Center (PSRC), The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran
| | - M Rahimifard
- Toxicology and Diseases Group, Pharmaceutical Sciences Research Center (PSRC), The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran
| | - S Sabuncuoglu
- Department of Pharmaceutical Toxicology, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey
| | - M Abdollahi
- Toxicology and Diseases Group, Pharmaceutical Sciences Research Center (PSRC), The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Toxicology and Pharmacology, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
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8
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Shafer TJ, Brown JP, Lynch B, Davila-Montero S, Wallace K, Friedman KP. Evaluation of Chemical Effects on Network Formation in Cortical Neurons Grown on Microelectrode Arrays. Toxicol Sci 2020; 169:436-455. [PMID: 30816951 DOI: 10.1093/toxsci/kfz052] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Thousands of chemicals to which humans are potentially exposed have not been evaluated for potential developmental neurotoxicity (DNT), driving efforts to develop a battery of in vitro screening approaches for DNT hazard. Here, 136 unique chemicals were evaluated for potential DNT hazard using a network formation assay (NFA) in cortical cells grown on microelectrode arrays. The effects of chemical exposure from 2 h postplating through 12 days in vitro (DIV) on network formation were evaluated at DIV 5, 7, 9, and 12, with cell viability assessed at DIV 12. Only 82 chemicals altered at least 1 network development parameter. Assay results were reproducible; 10 chemicals tested as biological replicates yielded qualitative results that were 100% concordant, with consistent potency values. Toxicological tipping points were determined for 58 chemicals and were similar to or lower than the lowest 50% effect concentrations (EC50) for all parameters. When EC50 and tipping point values from the NFA were compared to the range of potencies observed in ToxCast assays, the NFA EC50 values were less than the lower quartile for ToxCast assay potencies for a subset of chemicals, many of which are acutely neurotoxic in vivo. For 13 chemicals with available in vivo DNT data, estimated administered equivalent doses based on NFA results were similar to or lower than administered doses in vivo. Collectively, these results indicate that the NFA is sensitive to chemicals acting on nervous system function and will be a valuable contribution to an in vitro DNT screening battery.
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Affiliation(s)
- Timothy J Shafer
- Integrated Systems Toxicology Division, NHEERL, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711
| | - Jasmine P Brown
- Integrated Systems Toxicology Division, NHEERL, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711.,Graduate Program in Public Health, University of Michigan, Ann Arbor, MI
| | - Brittany Lynch
- Tandon School of Engineering, New York University, Brooklyn, New York 11201
| | - Sylmarie Davila-Montero
- Department of Electrical and Computer Engineering, Michigan State University, E. Lansing, Michigan 48824
| | - Kathleen Wallace
- Integrated Systems Toxicology Division, NHEERL, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711
| | - Katie Paul Friedman
- National Center for Computational Toxicology, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711
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9
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Otsuka A, Shimomura K, Niwa H, Kagawa N. The presence of a conspecific induces risk-taking behaviour and enlargement of somata size of dopaminergic neurons in the brain of male medaka fish. JOURNAL OF FISH BIOLOGY 2020; 96:1014-1023. [PMID: 32060927 DOI: 10.1111/jfb.14293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/30/2020] [Accepted: 02/13/2020] [Indexed: 06/10/2023]
Abstract
Boldness and risk-taking behaviours in animals are important traits to obtain advantages such as habitation, food resources, reproductive success and social dominance. Risk-taking behaviour is influenced by physiological and environmental conditions; however, whether individual fish become bolder by the presence of conspecifics remains unknown. In this study, a light-dark preference test was conducted using medaka fish (Oryzias latipes) with or without a neighbouring conspecific. It was found that individual medaka male fish preferred a light environment and avoided a dark environment, whereas the display of a neighbouring conspecific enhanced the time the male spent in the dark environment (i.e., this condition encouraged risk-taking). The blood glucose level increased in fish confined to the dark condition but did not increase in light-preferring fish and risk-taking fish. Large somata expressing tyrosine hydroxylase, which is the rate-limiting enzyme in dopamine synthesis, were detected in the telencephalic and diencephalic brain regions in risk-taking medaka, whereas large somata were detected in the diencephalic region in medaka confined to the dark condition. These findings indicated that medaka is a good fish model to explore the central roles of dopaminergic neurons in the telencephalon and the diencephalon, which regulate risk-taking behaviour.
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Affiliation(s)
- Airi Otsuka
- Department of Life Science, Faculty of Science and Technology, Kindai University, Higashiosaka, Japan
| | - Kenta Shimomura
- Department of Life Science, Faculty of Science and Technology, Kindai University, Higashiosaka, Japan
| | - Haruka Niwa
- Department of Life Science, Faculty of Science and Technology, Kindai University, Higashiosaka, Japan
| | - Nao Kagawa
- Department of Life Science, Faculty of Science and Technology, Kindai University, Higashiosaka, Japan
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10
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Kranaster P, Karreman C, Dold JEGA, Krebs A, Funke M, Holzer AK, Klima S, Nyffeler J, Helfrich S, Wittmann V, Leist M. Time and space-resolved quantification of plasma membrane sialylation for measurements of cell function and neurotoxicity. Arch Toxicol 2019; 94:449-467. [PMID: 31828357 DOI: 10.1007/s00204-019-02642-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 12/02/2019] [Indexed: 12/28/2022]
Abstract
While there are many methods to quantify the synthesis, localization, and pool sizes of proteins and DNA during physiological responses and toxicological stress, only few approaches allow following the fate of carbohydrates. One of them is metabolic glycoengineering (MGE), which makes use of chemically modified sugars (CMS) that enter the cellular biosynthesis pathways leading to glycoproteins and glycolipids. The CMS can subsequently be coupled (via bio-orthogonal chemical reactions) to tags that are quantifiable by microscopic imaging. We asked here, whether MGE can be used in a quantitative and time-resolved way to study neuronal glycoprotein synthesis and its impairment. We focused on the detection of sialic acid (Sia), by feeding human neurons the biosynthetic precursor N-acetyl-mannosamine, modified by an azide tag. Using this system, we identified non-toxic conditions that allowed live cell labeling with high spatial and temporal resolution, as well as the quantification of cell surface Sia. Using combinations of immunostaining, chromatography, and western blotting, we quantified the percentage of cellular label incorporation and effects on glycoproteins such as polysialylated neural cell adhesion molecule. A specific imaging algorithm was used to quantify Sia incorporation into neuronal projections, as potential measure of complex cell function in toxicological studies. When various toxicants were studied, we identified a subgroup (mitochondrial respiration inhibitors) that affected neurite glycan levels several hours before any other viability parameter was affected. The MGE-based neurotoxicity assay, thus allowed the identification of subtle impairments of neurochemical function with very high sensitivity.
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Affiliation(s)
- Petra Kranaster
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457, Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany
| | - Christiaan Karreman
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457, Konstanz, Germany
| | - Jeremias E G A Dold
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany.,Department of Chemistry, University of Konstanz, 78457, Konstanz, Germany
| | - Alice Krebs
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457, Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany
| | - Melina Funke
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457, Konstanz, Germany
| | - Anna-Katharina Holzer
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457, Konstanz, Germany
| | - Stefanie Klima
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457, Konstanz, Germany.,Kooperatives Promotionskolleg (KPK) InViTe, University of Konstanz, 78457, Konstanz, Germany
| | - Johanna Nyffeler
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457, Konstanz, Germany.,Environmental Protection Agency, Durham, NC, USA
| | - Stefan Helfrich
- The Bioimaging Center, University of Konstanz, 78457, Konstanz, Germany.,KNIME GmbH, 78467, Konstanz, Germany
| | - Valentin Wittmann
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany.,Department of Chemistry, University of Konstanz, 78457, Konstanz, Germany
| | - Marcel Leist
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457, Konstanz, Germany. .,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany.
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11
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The Role of Xenobiotics and Trace Metals in Parkinson’s Disease. Mol Neurobiol 2019; 57:1405-1417. [DOI: 10.1007/s12035-019-01832-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/01/2019] [Indexed: 12/21/2022]
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12
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Delp J, Funke M, Rudolf F, Cediel A, Bennekou SH, van der Stel W, Carta G, Jennings P, Toma C, Gardner I, van de Water B, Forsby A, Leist M. Development of a neurotoxicity assay that is tuned to detect mitochondrial toxicants. Arch Toxicol 2019; 93:1585-1608. [PMID: 31190196 DOI: 10.1007/s00204-019-02473-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 05/07/2019] [Indexed: 12/18/2022]
Abstract
Many neurotoxicants affect energy metabolism in man, but currently available test methods may still fail to predict mito- and neurotoxicity. We addressed this issue using LUHMES cells, i.e., human neuronal precursors that easily differentiate into mature neurons. Within the NeuriTox assay, they have been used to screen for neurotoxicants. Our new approach is based on culturing the cells in either glucose or galactose (Glc-Gal-NeuriTox) as the main carbohydrate source during toxicity testing. Using this Glc-Gal-NeuriTox assay, 52 mitochondrial and non-mitochondrial toxicants were tested. The panel of chemicals comprised 11 inhibitors of mitochondrial respiratory chain complex I (cI), 4 inhibitors of cII, 8 of cIII, and 2 of cIV; 8 toxicants were included as they are assumed to be mitochondrial uncouplers. In galactose, cells became more dependent on mitochondrial function, which made them 2-3 orders of magnitude more sensitive to various mitotoxicants. Moreover, galactose enhanced the specific neurotoxicity (destruction of neurites) compared to a general cytotoxicity (plasma membrane lysis) of the toxicants. The Glc-Gal-NeuriTox assay worked particularly well for inhibitors of cI and cIII, while the toxicity of uncouplers and non-mitochondrial toxicants did not differ significantly upon glucose ↔ galactose exchange. As a secondary assay, we developed a method to quantify the inhibition of all mitochondrial respiratory chain functions/complexes in LUHMES cells. The combination of the Glc-Gal-NeuriTox neurotoxicity screening assay with the mechanistic follow up of target site identification allowed both, a more sensitive detection of neurotoxicants and a sharper definition of the mode of action of mitochondrial toxicants.
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Affiliation(s)
- Johannes Delp
- Chair for In Vitro Toxicology and Biomedicine, Department of Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Constance, Germany
- Cooperative Doctorate College InViTe, University of Konstanz, Constance, Germany
| | - Melina Funke
- Chair for In Vitro Toxicology and Biomedicine, Department of Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Constance, Germany
| | - Franziska Rudolf
- Chair for In Vitro Toxicology and Biomedicine, Department of Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Constance, Germany
| | - Andrea Cediel
- Swetox Unit for Toxicological Sciences, Karolinska Institutet, Stockholm, Sweden
| | | | - Wanda van der Stel
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Giada Carta
- Division of Molecular and Computational Toxicology, Amsterdam Institute for Molecules, Medicines and Systems, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Paul Jennings
- Division of Molecular and Computational Toxicology, Amsterdam Institute for Molecules, Medicines and Systems, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Cosimo Toma
- Laboratory of Environmental Chemistry and Toxicology, Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via la Masa 19, 20156, Milan, Italy
| | | | - Bob van de Water
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Anna Forsby
- Swetox Unit for Toxicological Sciences, Karolinska Institutet, Stockholm, Sweden
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Marcel Leist
- Chair for In Vitro Toxicology and Biomedicine, Department of Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Constance, Germany.
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13
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Major changes of cell function and toxicant sensitivity in cultured cells undergoing mild, quasi-natural genetic drift. Arch Toxicol 2018; 92:3487-3503. [PMID: 30298209 PMCID: PMC6290691 DOI: 10.1007/s00204-018-2326-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 06/19/2018] [Indexed: 12/11/2022]
Abstract
Genomic drift affects the functional properties of cell lines, and the reproducibility of data from in vitro studies. While chromosomal aberrations and mutations in single pivotal genes are well explored, little is known about effects of minor, possibly pleiotropic, genome changes. We addressed this question for the human dopaminergic neuronal precursor cell line LUHMES by comparing two subpopulations (SP) maintained either at the American-Type-Culture-Collection (ATCC) or by the original provider (UKN). Drastic differences in susceptibility towards the specific dopaminergic toxicant 1-methyl-4-phenylpyridinium (MPP+) were observed. Whole-genome sequencing was performed to identify underlying genetic differences. While both SP had normal chromosome structures, they displayed about 70 differences on the level of amino acid changing events. Some of these differences were confirmed biochemically, but none offered a direct explanation for the altered toxicant sensitivity pattern. As second approach, markers known to be relevant for the intended use of the cells were specifically tested. The “ATCC” cells rapidly down-regulated the dopamine-transporter and tyrosine-hydroxylase after differentiation, while “UKN” cells maintained functional levels. As the respective genes were not altered themselves, we conclude that polygenic complex upstream changes can have drastic effects on biochemical features and toxicological responses of relatively similar SP of cells.
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Olguín N, Müller ML, Rodríguez-Farré E, Suñol C. Neurotransmitter amines and antioxidant agents in neuronal protection against methylmercury-induced cytotoxicity in primary cultures of mice cortical neurons. Neurotoxicology 2018; 69:278-287. [PMID: 30075218 DOI: 10.1016/j.neuro.2018.07.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 07/26/2018] [Accepted: 07/30/2018] [Indexed: 12/23/2022]
Abstract
Methylmercury (MeHg) is an environmental toxicant with detrimental effects on the developing brain and adult nervous system. The main mechanisms identified include oxidative stress, changes in intracellular calcium, mitochondrial changes, inhibition of glutamate uptake, of protein synthesis and disruption of microtubules. However, little is known about mechanisms of protection against MeHg neurotoxicity. We found that resveratrol (10 μM) and ascorbic acid (200 μM) protected MeHg-induced cell death in primary cultures of cortical neurons. In this work, we aimed at finding additional targets that may be related to MeHg mode of action in cell toxicity with special emphasis in cell protection. We wonder whether neurotransmitters may affect the MeHg effects on neuronal death. Our findings show that neurons exposed to low MeHg concentrations exhibit less mortality if co-exposed to 10 μM dopamine (DA). However, DA metabolites, HVA (homovanillic acid) and DOPAC (3,4-dihydroxyphenylacetic acid) are not responsible for such protection. Furthermore, both DA D1 and D2 receptors agonists showed a protective effect against MeHg toxicity. It is striking though that DA receptor antagonists SKF83566 (10 μM) and haloperidol (10 μM) did not inhibit DA protection against MeHg. In addition, the protective effect of 10 μM DA against MeHg-induced toxicity was not affected by additional organochlorine pollutants exposure. Our results also demonstrate that cells exposed to MeHg in presence of 100 μM acetylcholine (ACh), show an increase in cell mortality at the "threshold value" of 100 nM MeHg. Finally, norepinephrine (10 μM) and serotonin (20 μM) also had an effect on cell protection. Altogether, we propose to further investigate the additional mechanisms that may be playing an important role in MeHg-induced cytotoxicity.
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Affiliation(s)
- Nair Olguín
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC - IDIBAPS, CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
| | - Marie-Lena Müller
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC - IDIBAPS, CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
| | - Eduard Rodríguez-Farré
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC - IDIBAPS, CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
| | - Cristina Suñol
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC - IDIBAPS, CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.
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15
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Go S, Kurita H, Matsumoto K, Hatano M, Inden M, Hozumi I. Methylmercury causes epigenetic suppression of the tyrosine hydroxylase gene in an in vitro neuronal differentiation model. Biochem Biophys Res Commun 2018; 502:435-441. [PMID: 29856999 DOI: 10.1016/j.bbrc.2018.05.162] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 05/24/2018] [Indexed: 10/14/2022]
Abstract
Methylmercury (MeHg) is the causative substance of Minamata disease, which is associated with various neurological disorders such as sensory disturbance and ataxia. It has been suggested low-level dietary intake of MeHg from MeHg-containing fish during gestation adversely affects the fetus. In our study, we investigated the toxicological effects of MeHg exposure on neuronal differentiation focusing on epigenetics. We used human fetal brain-derived immortalized cells (LUHMES cells) as a human neuronal differentiation model. Cell viability, neuronal, and catecholamine markers in LUHMES cells were assessed after exposure to MeHg (0-1000 nM) for 6 days (from day 2 to day 8 of neuronal differentiation). Cell viability on day 8 was not affected by exposure to 1 nM MeHg for 6 days. mRNA levels of AADC, DBH, TUJ1, and SYN1 also were unaffected by MeHg exposure. In contrast, levels of TH, the rate-limiting enzyme for dopamine synthesis, were significantly decreased after MeHg exposure. Acetylated histone H3, acetylated histone H3 lysine 9, and tri-methyl histone H3 lysine 9 levels at the TH gene promoter were not altered by MeHg exposure. However, tri-methylation of histone H3 lysine 27 levels, related to transcriptional repression, were significantly increased at the TH gene promotor after MeHg exposure. In summary, MeHg exposure during neuronal differentiation led to epigenetic changes that repressed TH gene expression. This study provides useful insights into the toxicological mechanisms underlying the effects of developmental MeHg exposure during neuronal differentiation.
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Affiliation(s)
- Suzuna Go
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Hisaka Kurita
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Kana Matsumoto
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Manami Hatano
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Masatoshi Inden
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Isao Hozumi
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan.
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16
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Bal-Price A, Hogberg HT, Crofton KM, Daneshian M, FitzGerald RE, Fritsche E, Heinonen T, Hougaard Bennekou S, Klima S, Piersma AH, Sachana M, Shafer TJ, Terron A, Monnet-Tschudi F, Viviani B, Waldmann T, Westerink RHS, Wilks MF, Witters H, Zurich MG, Leist M. Recommendation on test readiness criteria for new approach methods in toxicology: Exemplified for developmental neurotoxicity. ALTEX-ALTERNATIVES TO ANIMAL EXPERIMENTATION 2018; 35:306-352. [PMID: 29485663 DOI: 10.14573/altex.1712081] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 01/29/2018] [Indexed: 01/06/2023]
Abstract
Multiple non-animal-based test methods have never been formally validated. In order to use such new approach methods (NAMs) in a regulatory context, criteria to define their readiness are necessary. The field of developmental neurotoxicity (DNT) testing is used to exemplify the application of readiness criteria. The costs and number of untested chemicals are overwhelming for in vivo DNT testing. Thus, there is a need for inexpensive, high-throughput NAMs, to obtain initial information on potential hazards, and to allow prioritization for further testing. A background on the regulatory and scientific status of DNT testing is provided showing different types of test readiness levels, depending on the intended use of data from NAMs. Readiness criteria, compiled during a stakeholder workshop, uniting scientists from academia, industry and regulatory authorities are presented. An important step beyond the listing of criteria, was the suggestion for a preliminary scoring scheme. On this basis a (semi)-quantitative analysis process was assembled on test readiness of 17 NAMs with respect to various uses (e.g. prioritization/screening, risk assessment). The scoring results suggest that several assays are currently at high readiness levels. Therefore, suggestions are made on how DNT NAMs may be assembled into an integrated approach to testing and assessment (IATA). In parallel, the testing state in these assays was compiled for more than 1000 compounds. Finally, a vision is presented on how further NAM development may be guided by knowledge of signaling pathways necessary for brain development, DNT pathophysiology, and relevant adverse outcome pathways (AOP).
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Affiliation(s)
- Anna Bal-Price
- European Commission, Joint Research Centre (EC JRC), Ispra (VA), Italy
| | - Helena T Hogberg
- Center for Alternatives to Animal Testing (CAAT), Johns Hopkins University, Baltimore, MD, USA
| | - Kevin M Crofton
- National Centre for Computational Toxicology, US EPA, RTP, Washington, NC, USA
| | - Mardas Daneshian
- Center for Alternatives to Animal Testing, CAAT-Europe, University of Konstanz, Konstanz, Germany
| | - Rex E FitzGerald
- Swiss Centre for Human Applied Toxicology, SCAHT, University of Basle, Switzerland
| | - Ellen Fritsche
- IUF - Leibniz Research Institute for Environmental Medicine & Heinrich-Heine-University, Düsseldorf, Germany
| | - Tuula Heinonen
- Finnish Centre for Alternative Methods (FICAM), University of Tampere, Tampere, Finland
| | | | - Stefanie Klima
- In vitro Toxicology and Biomedicine, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Aldert H Piersma
- RIVM, National Institute for Public Health and the Environment, Bilthoven, and Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
| | - Magdalini Sachana
- Organisation for Economic Co-operation and Development (OECD), Paris, France
| | - Timothy J Shafer
- National Centre for Computational Toxicology, US EPA, RTP, Washington, NC, USA
| | | | - Florianne Monnet-Tschudi
- Swiss Centre for Human Applied Toxicology, SCAHT, University of Basle, Switzerland.,Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Barbara Viviani
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Italy
| | - Tanja Waldmann
- In vitro Toxicology and Biomedicine, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Remco H S Westerink
- Neurotoxicology Research Group, Institute for Risk Assessment Sciences (IRAS), Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Martin F Wilks
- Swiss Centre for Human Applied Toxicology, SCAHT, University of Basle, Switzerland
| | - Hilda Witters
- VITO, Flemish Institute for Technological Research, Unit Environmental Risk and Health, Mol, Belgium
| | - Marie-Gabrielle Zurich
- Swiss Centre for Human Applied Toxicology, SCAHT, University of Basle, Switzerland.,Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Marcel Leist
- Center for Alternatives to Animal Testing, CAAT-Europe, University of Konstanz, Konstanz, Germany.,In vitro Toxicology and Biomedicine, Department of Biology, University of Konstanz, Konstanz, Germany
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17
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Chan MC, Bautista E, Alvarado-Cruz I, Quintanilla-Vega B, Segovia J. Inorganic mercury prevents the differentiation of SH-SY5Y cells: Amyloid precursor protein, microtubule associated proteins and ROS as potential targets. J Trace Elem Med Biol 2017; 41:119-128. [PMID: 28209268 DOI: 10.1016/j.jtemb.2017.02.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 01/16/2017] [Accepted: 02/05/2017] [Indexed: 10/20/2022]
Abstract
Exposure to mercury (Hg) occurs through different pathways and forms including methylmecury (MeHg) from seafood and rice, ethylmercury (EtHg), and elemental Hg (Hg0) from dental amalgams and artisanal gold mining. Once in the brain all these forms are transformed to inorganic Hg (I-Hg), where it bioaccumulates and remains for long periods. Hg is a well-known neurotoxicant, with its most damaging effects reported during brain development, when cellular key events, such as cell differentiation take place. A considerable number of studies report an impairment of neuronal differentiation due to MeHg exposure, however the effects of I-Hg, an important form of Hg found in brain, have received less attention. In this study, we decided to examine the effects of I-Hg exposure (5, 10 and 20μM) on the differentiation of SH-SY5Y cells induced by retinoic acid (RA, 10μM). We observed extension of neuritic processes and increased expression of neuronal markers (MAP2, tubulin-βIII, and Tau) after RA stimulation, all these effects were decreased by the co-exposure to I-Hg. Interestingly, I-Hg increased the levels of reactive oxygen species (ROS) and nitric oxide (NO) accompanied with increased levels of inducible nitric oxide synthase (iNOS) and, dimethylarginine dimethylaminohydrolase 1 (DDHA1). Remarkably I-Hg decreased levels of nitric oxide synthase neuronal (nNOS). Moreover I-Hg reduced the levels of tyrosine hydroxylase (TH) and amyloid precursor protein (APP) a protein recently involved in neuronal differentiation. These data suggest that the exposure to I-Hg impairs cell differentiation, and point to new potential targets of Hg toxicity such as APP and NO signaling.
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Affiliation(s)
- Miguel Chin Chan
- Departmento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico; Facultad de Ciencias Químico Biológicas, Universidad Autónoma de Campeche, Campeche 4039, Mexico
| | - Elizabeth Bautista
- Departmento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico; Facultad de Ciencias de la Salud, Universidad Anáhuac Norte, 52786, Huixquilucan, Mexico
| | - Isabel Alvarado-Cruz
- Departmento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico
| | - Betzabet Quintanilla-Vega
- Departmento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico
| | - José Segovia
- Departmento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico.
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18
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Impairment of human neural crest cell migration by prolonged exposure to interferon-beta. Arch Toxicol 2017; 91:3385-3402. [PMID: 28365849 PMCID: PMC5608792 DOI: 10.1007/s00204-017-1966-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 03/21/2017] [Indexed: 12/31/2022]
Abstract
Human cell-based toxicological assays have been used successfully to detect known toxicants, and to distinguish them from negative controls. However, there is at present little experience on how to deal with hits from screens of compounds with yet unknown hazard. As a case study to this issue, we characterized human interferon-beta (IFNβ) as potential developmental toxicant affecting neural crest cells (NCC). The protein was identified as a hit during a screen of clinically used drugs in the ‘migration inhibition of neural crest’ (MINC) assay. Concentration–response studies in the MINC combined with immunocytochemistry and mRNA quantification of cellular markers showed that IFNβ inhibited NCC migration at concentrations as low as 20 pM. The effective concentrations found here correspond to levels found in human plasma, and they were neither cytostatic nor cytotoxic nor did they did they affect the differentiation state and overall phenotype of NCC. Data from two other migration assays confirmed that picomolar concentration of IFNβ reduced the motility of NCC, while other interferons were less potent. The activation of JAK kinase by IFNβ, as suggested by bioinformatics analysis of the transcriptome changes, was confirmed by biochemical methods. The degree and duration of pathway activation correlated with the extent of migration inhibition, and pharmacological block of this signaling pathway before, or up to 6 h after exposure to the cytokine prevented the effects of IFNβ on migration. Thus, the reduction of vital functions of human NCC is a hitherto unknown potential hazard of endogenous or pharmacologically applied interferons.
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19
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Farina M, Aschner M. Methylmercury-Induced Neurotoxicity: Focus on Pro-oxidative Events and Related Consequences. ADVANCES IN NEUROBIOLOGY 2017; 18:267-286. [DOI: 10.1007/978-3-319-60189-2_13] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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20
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Yao X, Yin N, Faiola F. Stem cell toxicology: a powerful tool to assess pollution effects on human health. Natl Sci Rev 2016. [DOI: 10.1093/nsr/nww089] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
AbstractEnvironmental pollution is a global problem; the lack of comprehensive toxicological assessments may lead to increased health risks. To fully understand the health effects of pollution, it is paramount to implement fast, efficient and specific toxicity screening that relies on human models rather than on time-consuming, expensive and often inaccurate tests involving live animals. Human stem cell toxicology represents a valid alternative to traditional toxicity assays because it takes advantage of the ability of stem cells to differentiate into multiple cell types and tissues of the human body. Thus, this branch of toxicology provides a possibility to assess cellular, embryonic, developmental, reproductive and functional toxicity in vitro within a single system highly relevant to human physiology. In this review, we describe the development, performance and future perspectives of stem cell toxicology, with an emphasis on how it can meet the increasing challenges posed by environmental pollution in the modern world.
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Affiliation(s)
- Xinglei Yao
- Stake Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nuoya Yin
- Stake Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Francesco Faiola
- Stake Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
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21
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Kleiderman S, Gutbier S, Ugur Tufekci K, Ortega F, Sá JV, Teixeira AP, Brito C, Glaab E, Berninger B, Alves PM, Leist M. Conversion of Nonproliferating Astrocytes into Neurogenic Neural Stem Cells: Control by FGF2 and Interferon-γ. Stem Cells 2016; 34:2861-2874. [PMID: 27603577 DOI: 10.1002/stem.2483] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 07/24/2016] [Accepted: 07/29/2016] [Indexed: 01/05/2023]
Abstract
Conversion of astrocytes to neurons, via de-differentiation to neural stem cells (NSC), may be a new approach to treat neurodegenerative diseases and brain injuries. The signaling factors affecting such a cell conversion are poorly understood, and they are hard to identify in complex disease models or conventional cell cultures. To address this question, we developed a serum-free, strictly controlled culture system of pure and homogeneous "astrocytes generated from murine embryonic stem cells (ESC)." These stem cell derived astrocytes (mAGES), as well as standard primary astrocytes resumed proliferation upon addition of FGF. The signaling of FGF receptor tyrosine kinase converted GFAP-positive mAGES to nestin-positive NSC. ERK phosphorylation was necessary, but not sufficient, for cell cycle re-entry, as EGF triggered no de-differentiation. The NSC obtained by de-differentiation of mAGES were similar to those obtained directly by differentiation of ESC, as evidenced by standard phenotyping, and also by transcriptome mapping, metabolic profiling, and by differentiation to neurons or astrocytes. The de-differentiation was negatively affected by inflammatory mediators, and in particular, interferon-γ strongly impaired the formation of NSC from mAGES by a pathway involving phosphorylation of STAT1, but not the generation of nitric oxide. Thus, two antagonistic signaling pathways were identified here that affect fate conversion of astrocytes independent of genetic manipulation. The complex interplay of the respective signaling molecules that promote/inhibit astrocyte de-differentiation may explain why astrocytes do not readily form neural stem cells in most diseases. Increased knowledge of such factors may provide therapeutic opportunities to favor such conversions. Stem Cells 2016;34:2861-2874.
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Affiliation(s)
- Susanne Kleiderman
- Department of Biology, The Doerenkamp-Zbinden Chair of in-vitro Toxicology and Biomedicine/Alternatives to Animal Experimentation, University of Konstanz, Konstanz, Germany
| | - Simon Gutbier
- Department of Biology, The Doerenkamp-Zbinden Chair of in-vitro Toxicology and Biomedicine/Alternatives to Animal Experimentation, University of Konstanz, Konstanz, Germany
| | - Kemal Ugur Tufekci
- Department of Biology, The Doerenkamp-Zbinden Chair of in-vitro Toxicology and Biomedicine/Alternatives to Animal Experimentation, University of Konstanz, Konstanz, Germany
- Department of Neuroscience, Institute of Health Sciences, Dokuz Eylul University, Inciralti, Izmir, Turkey
| | - Felipe Ortega
- Institute/Department of Physiological Chemistry, Research Group Adult Neurogenesis and Cellular Reprogramming, Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
- Department of Biochemistry and Molecular Biology, Biochemistry and Molecular Biology Department, Faculty of Veterinary Medicine, Complutense University, Avenue Puerta de Hierro, Institute of Neurochemistry (IUIN), Spain and Health Research Institute of the Hospital Clinico San Carlos (IdISSC), Madrid, Spain
| | - João V Sá
- IBET, Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, Portugal
| | - Ana P Teixeira
- IBET, Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, Portugal
| | - Catarina Brito
- IBET, Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, Portugal
| | - Enrico Glaab
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Belvaux, Luxembourg
| | - Benedikt Berninger
- Institute/Department of Physiological Chemistry, Research Group Adult Neurogenesis and Cellular Reprogramming, Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Paula M Alves
- IBET, Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, Portugal
| | - Marcel Leist
- Department of Biology, The Doerenkamp-Zbinden Chair of in-vitro Toxicology and Biomedicine/Alternatives to Animal Experimentation, University of Konstanz, Konstanz, Germany
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22
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Brown JP, Hall D, Frank CL, Wallace K, Mundy WR, Shafer TJ. Editor's Highlight: Evaluation of a Microelectrode Array-Based Assay for Neural Network Ontogeny Using Training Set Chemicals. Toxicol Sci 2016; 154:126-139. [PMID: 27492221 DOI: 10.1093/toxsci/kfw147] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Thousands of compounds in the environment have not been characterized for developmental neurotoxicity (DNT) hazard. To address this issue, methods to screen compounds rapidly for DNT hazard evaluation are necessary and are being developed for key neurodevelopmental processes. In order to develop an assay for network formation, this study evaluated effects of a training set of chemicals on network ontogeny by measuring spontaneous electrical activity in neural networks grown on microelectrode arrays (MEAs). Rat (0-24 h old) primary cortical cells were plated in 48 well-MEA plates and exposed to 6 compounds: acetaminophen, bisindolylmaleimide-1 (Bis-1), domoic acid, mevastatin, sodium orthovanadate, and loperamide for a period of 12 days. Spontaneous network activity was recorded on days 2, 5, 7, 9, and 12 and viability was assessed using the Cell Titer Blue assay on day 12. Network activity (e.g. mean firing rate [MFR], burst rate [BR], etc), increased between days 5 and 12. Random Forest analysis indicated that across all compounds and times, temporal correlation of firing patterns (r), MFR, BR, number of active electrodes and % of spikes in a burst were the most influential parameters in separating control from treated wells. All compounds except acetaminophen (≤ 30 µM) caused concentration-related effects on one or more of these parameters. Domoic acid and sodium orthovanadate altered several of these parameters in the absence of cytotoxicity. Although cytotoxicity was observed with Bis1, mevastatin, and loperamide, some parameters were affected by these compounds at concentrations below those resulting in cytotoxicity. These results demonstrate that this assay may be suitable for screening of compounds for DNT hazard identification.
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Affiliation(s)
| | - Diana Hall
- NHEERL, US EPA, Research Triangle Park, NC, USA
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23
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Schmidt BZ, Lehmann M, Gutbier S, Nembo E, Noel S, Smirnova L, Forsby A, Hescheler J, Avci HX, Hartung T, Leist M, Kobolák J, Dinnyés A. In vitro acute and developmental neurotoxicity screening: an overview of cellular platforms and high-throughput technical possibilities. Arch Toxicol 2016; 91:1-33. [PMID: 27492622 DOI: 10.1007/s00204-016-1805-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 07/07/2016] [Indexed: 01/03/2023]
Abstract
Neurotoxicity and developmental neurotoxicity are important issues of chemical hazard assessment. Since the interpretation of animal data and their extrapolation to man is challenging, and the amount of substances with information gaps exceeds present animal testing capacities, there is a big demand for in vitro tests to provide initial information and to prioritize for further evaluation. During the last decade, many in vitro tests emerged. These are based on animal cells, human tumour cell lines, primary cells, immortalized cell lines, embryonic stem cells, or induced pluripotent stem cells. They differ in their read-outs and range from simple viability assays to complex functional endpoints such as neural crest cell migration. Monitoring of toxicological effects on differentiation often requires multiomics approaches, while the acute disturbance of neuronal functions may be analysed by assessing electrophysiological features. Extrapolation from in vitro data to humans requires a deep understanding of the test system biology, of the endpoints used, and of the applicability domains of the tests. Moreover, it is important that these be combined in the right way to assess toxicity. Therefore, knowledge on the advantages and disadvantages of all cellular platforms, endpoints, and analytical methods is essential when establishing in vitro test systems for different aspects of neurotoxicity. The elements of a test, and their evaluation, are discussed here in the context of comprehensive prediction of potential hazardous effects of a compound. We summarize the main cellular characteristics underlying neurotoxicity, present an overview of cellular platforms and read-out combinations assessing distinct parts of acute and developmental neurotoxicology, and highlight especially the use of stem cell-based test systems to close gaps in the available battery of tests.
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Affiliation(s)
- Béla Z Schmidt
- BioTalentum Ltd., Gödöllő, Hungary.,Stem Cell Biology and Embryology Unit, Department of Development and Regeneration, Stem Cell Institute Leuven, KU Leuven, Leuven, Belgium
| | - Martin Lehmann
- BioTalentum Ltd., Gödöllő, Hungary.,Institute of Neurophysiology and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Simon Gutbier
- Doerenkamp-Zbinden Chair for In Vitro Toxicology and Biomedicine, University of Konstanz, Constance, Germany
| | - Erastus Nembo
- BioTalentum Ltd., Gödöllő, Hungary.,Institute of Neurophysiology and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Sabrina Noel
- Louvain Centre for Toxicology and Applied Pharmacology, Université Catholique de Louvain, Brussels, Belgium
| | - Lena Smirnova
- Center for Alternatives to Animal Testing, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Anna Forsby
- Swedish Toxicology Research Center (Swetox), Södertälje, Sweden.,Department of Neurochemistry, Stockholm University, Stockholm, Sweden
| | - Jürgen Hescheler
- Institute of Neurophysiology and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Hasan X Avci
- BioTalentum Ltd., Gödöllő, Hungary.,Department of Medical Chemistry, University of Szeged, Szeged, Hungary
| | - Thomas Hartung
- Center for Alternatives to Animal Testing, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Marcel Leist
- Doerenkamp-Zbinden Chair for In Vitro Toxicology and Biomedicine, University of Konstanz, Constance, Germany
| | | | - András Dinnyés
- BioTalentum Ltd., Gödöllő, Hungary. .,Molecular Animal Biotechnology Laboratory, Szent István University, Gödöllő, 2100, Hungary.
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Aschner M, Ceccatelli S, Daneshian M, Fritsche E, Hasiwa N, Hartung T, Hogberg HT, Leist M, Li A, Mundi WR, Padilla S, Piersma AH, Bal-Price A, Seiler A, Westerink RH, Zimmer B, Lein PJ. Reference compounds for alternative test methods to indicate developmental neurotoxicity (DNT) potential of chemicals: example lists and criteria for their selection and use. ALTEX-ALTERNATIVES TO ANIMAL EXPERIMENTATION 2016; 34:49-74. [PMID: 27452664 PMCID: PMC5250586 DOI: 10.14573/altex.1604201] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/09/2016] [Indexed: 11/23/2022]
Abstract
There is a paucity of information concerning the developmental neurotoxicity (DNT) hazard posed by industrial and environmental chemicals. New testing approaches will most likely be based on batteries of alternative and complementary (non-animal) tests. As DNT is assumed to result from the modulation of fundamental neurodevelopmental processes (such as neuronal differentiation, precursor cell migration or neuronal network formation) by chemicals, the first generation of alternative DNT tests target these processes. The advantage of such types of assays is that they capture toxicants with multiple targets and modes-of-action. Moreover, the processes modelled by the assays can be linked to toxicity endophenotypes, i.e. alterations in neural connectivity that form the basis for neurofunctional deficits in man. The authors of this review convened in a workshop to define criteria for the selection of positive/negative controls, to prepare recommendations on their use, and to initiate the setup of a directory of reference chemicals. For initial technical optimization of tests, a set of >50 endpoint-specific control compounds was identified. For further test development, an additional “test” set of 33 chemicals considered to act directly as bona fide DNT toxicants is proposed, and each chemical is annotated to the extent it fulfills these criteria. A tabular compilation of the original literature used to select the test set chemicals provides information on statistical procedures, and toxic/non-toxic doses (both for pups and dams). Suggestions are provided on how to use the >100 compounds (including negative controls) compiled here to address specificity, adversity and use of alternative test systems.
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Affiliation(s)
| | | | - Mardas Daneshian
- Center for Alternatives to Animal Testing-Europe (CAAT-Europe), University of Konstanz, Germany
| | - Ellen Fritsche
- Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany
| | - Nina Hasiwa
- Center for Alternatives to Animal Testing-Europe (CAAT-Europe), University of Konstanz, Germany
| | - Thomas Hartung
- Center for Alternatives to Animal Testing-Europe (CAAT-Europe), University of Konstanz, Germany.,Center for Alternatives to Animal Testing (CAAT), The Johns Hopkins University, Baltimore, MD, USA
| | - Helena T Hogberg
- Center for Alternatives to Animal Testing (CAAT), The Johns Hopkins University, Baltimore, MD, USA
| | - Marcel Leist
- Center for Alternatives to Animal Testing-Europe (CAAT-Europe), University of Konstanz, Germany.,In vitro Toxicology and Biomedicine, Dept inaugurated by the Doerenkamp-Zbinden Foundation at the University of Konstanz, Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), Konstanz University
| | - Abby Li
- Exponent Inc.,San Francisco, USA
| | - William R Mundi
- United States Environmental Protection Agency (USEPA), NHEERL, Research Triangle Park, NC, USA
| | - Stephanie Padilla
- United States Environmental Protection Agency (USEPA), NHEERL, Research Triangle Park, NC, USA
| | - Aldert H Piersma
- National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.,Institute for Risk Assessment Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Anna Bal-Price
- European Commission Joint Research Centre, Institute for Health and Consumer Protection, Ispra, Italy
| | - Andrea Seiler
- Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Remco H Westerink
- Neurotoxicology Research Group, Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, The Netherlands
| | | | - Pamela J Lein
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, Portland, USA.,Department of Molecular Biosciences, University of California, Davis, USA
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25
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Fantetti KN, Gray EL, Ganesan P, Kulkarni A, O'Donnell LA. Interferon gamma protects neonatal neural stem/progenitor cells during measles virus infection of the brain. J Neuroinflammation 2016; 13:107. [PMID: 27178303 PMCID: PMC4867982 DOI: 10.1186/s12974-016-0571-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 05/06/2016] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND In the developing brain, self-renewing neural stem/progenitor cells (NSPC) give rise to neuronal and glial lineages. NSPC survival and differentiation can be altered by neurotropic viruses and by the anti-viral immune response. Several neurotropic viruses specifically target and infect NSPCs, in addition to inducing neuronal loss, which makes it difficult to distinguish between effects on NSPCs that are due to direct viral infection or due to the anti-viral immune response. METHODS We have investigated the impact of anti-viral immunity on NSPCs in measles virus (MV)-infected neonates. A neuron-restricted viral infection model was used, where NSPCs remain uninfected. Thus, an anti-viral immune response was induced without the confounding issue of NSPC infection. Two-transgenic mouse lines were used: CD46+ mice express the human isoform of CD46, the MV entry receptor, under the control of the neuron-specific enolase promoter; CD46+/IFNγ-KO mice lack the key anti-viral cytokine IFNγ. Multi-color flow cytometry and Western Blot analysis were used to quantify effects on NSPC, neuronal, and glial cell number, and quantify effects on IFNγ-mediated signaling and cell markers, respectively. RESULTS Flow cytometric analysis revealed that NSPCs were reduced in CD46+/IFNγ-KO mice at 3, 7, and 10 days post-infection (dpi), but were unaffected in CD46+ mice. Early neurons showed the greatest cell loss at 7 dpi in both genotypes, with no effect on mature neurons and glial cells. Thus, IFNγ protected against NSPC loss, but did not protect young neurons. Western Blot analyses on hippocampal explants showed reduced nestin expression in the absence of IFNγ, and reduced doublecortin and βIII-tubulin in both genotypes. Phosphorylation of STAT1 and STAT2 occurred independently of IFNγ in the hippocampus, albeit with distinct regulation of activation. CONCLUSIONS This is the first study to demonstrate bystander effects of anti-viral immunity on NSPC function. Our results show IFNγ protects the NSPC population during a neonatal viral CNS infection. Significant loss of NSPCs in CD46+/IFNγ-KO neonates suggests that the adaptive immune response is detrimental to NSPCs in the absence of IFNγ. These results reveal the importance and contribution of the anti-viral immune response to neuropathology and may be relevant to other neuroinflammatory conditions.
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Affiliation(s)
- Kristen N Fantetti
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, 600 Forbes Ave, Pittsburgh, PA, 15282, USA
| | - Erica L Gray
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, 600 Forbes Ave, Pittsburgh, PA, 15282, USA
| | - Priya Ganesan
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, 600 Forbes Ave, Pittsburgh, PA, 15282, USA
| | - Apurva Kulkarni
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, 600 Forbes Ave, Pittsburgh, PA, 15282, USA
| | - Lauren A O'Donnell
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, 600 Forbes Ave, Pittsburgh, PA, 15282, USA.
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Kleiderman S, Sá JV, Teixeira AP, Brito C, Gutbier S, Evje LG, Hadera MG, Glaab E, Henry M, Sachinidis A, Alves PM, Sonnewald U, Leist M. Functional and phenotypic differences of pure populations of stem cell-derived astrocytes and neuronal precursor cells. Glia 2015; 64:695-715. [DOI: 10.1002/glia.22954] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 11/19/2015] [Accepted: 11/23/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Susanne Kleiderman
- The Doerenkamp-Zbinden Chair of in-Vitro Toxicology and Biomedicine/Alternatives to Animal Experimentation; University of Konstanz; Konstanz Germany
| | - João V. Sá
- Instituto de Tecnologia Química e Biológica António Xavier; Universidade Nova de Lisboa; Av. da República 2780-157 Oeiras Portugal
- IBET; Instituto de Biologia Experimental e Tecnológica; Apartado 12 2780-901 Oeiras Portugal
| | - Ana P. Teixeira
- Instituto de Tecnologia Química e Biológica António Xavier; Universidade Nova de Lisboa; Av. da República 2780-157 Oeiras Portugal
- IBET; Instituto de Biologia Experimental e Tecnológica; Apartado 12 2780-901 Oeiras Portugal
| | - Catarina Brito
- Instituto de Tecnologia Química e Biológica António Xavier; Universidade Nova de Lisboa; Av. da República 2780-157 Oeiras Portugal
- IBET; Instituto de Biologia Experimental e Tecnológica; Apartado 12 2780-901 Oeiras Portugal
| | - Simon Gutbier
- The Doerenkamp-Zbinden Chair of in-Vitro Toxicology and Biomedicine/Alternatives to Animal Experimentation; University of Konstanz; Konstanz Germany
| | - Lars G. Evje
- Department of Earth Science, University of Bergen; Allégaten 41 5007 Bergen Norway
| | - Mussie G. Hadera
- Department of Pharmacy; College of Health Sciences; Mekelle University, Tigray Ethiopia
| | - Enrico Glaab
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg; Belvaux L-4366 Luxembourg
| | - Margit Henry
- Institute of Neurophysiology and Center for Molecular Medicine, Cologne (CMMC), University of Cologne; Cologne Germany
| | - Agapios Sachinidis
- Institute of Neurophysiology and Center for Molecular Medicine, Cologne (CMMC), University of Cologne; Cologne Germany
| | - Paula M. Alves
- Instituto de Tecnologia Química e Biológica António Xavier; Universidade Nova de Lisboa; Av. da República 2780-157 Oeiras Portugal
- IBET; Instituto de Biologia Experimental e Tecnológica; Apartado 12 2780-901 Oeiras Portugal
| | - Ursula Sonnewald
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; Copenhagen Denmark
- Department of Neuroscience; Norwegian University of Science and Technology; Faculty of Medicine; Trondheim Norway
| | - Marcel Leist
- The Doerenkamp-Zbinden Chair of in-Vitro Toxicology and Biomedicine/Alternatives to Animal Experimentation; University of Konstanz; Konstanz Germany
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27
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Sensitivity of neural stem cell survival, differentiation and neurite outgrowth within 3D hydrogels to environmental heavy metals. Toxicol Lett 2015; 242:9-22. [PMID: 26621541 DOI: 10.1016/j.toxlet.2015.11.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/30/2015] [Accepted: 11/21/2015] [Indexed: 01/13/2023]
Abstract
We investigated the sensitivity of embryonic murine neural stem cells exposed to 10 pM-10 μM concentrations of three heavy metals (Cd, Hg, Pb), continuously for 14 days within 3D collagen hydrogels. Critical endpoints for neurogenesis such as survival, differentiation and neurite outgrowth were assessed. Results suggest significant compromise in cell viability within the first four days at concentrations ≥10 nM, while lower concentrations induced a more delayed effect. Mercury and lead suppressed neural differentiation at as low as 10 pM concentration within 7 days, while all three metals inhibited neural and glial differentiation by day 14. Neurite outgrowth remained unaffected at lower cadmium or mercury concentrations (≤100 pM), but was completely repressed beyond day 1 at higher concentrations. Higher metal concentrations (≥100 pM) suppressed NSC differentiation to motor or dopaminergic neurons. Cytokines and chemokines released by NSCs, and the sub-cellular mechanisms by which metals induce damage to NSCs have been quantified and correlated to phenotypic data. The observed degree of toxicity in NSC cultures is in the order: lead>mercury>cadmium. Results point to the use of biomimetic 3D culture models to screen the toxic effects of heavy metals during developmental stages, and investigate their underlying mechanistic pathways.
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28
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Lohren H, Blagojevic L, Fitkau R, Ebert F, Schildknecht S, Leist M, Schwerdtle T. Toxicity of organic and inorganic mercury species in differentiated human neurons and human astrocytes. J Trace Elem Med Biol 2015; 32:200-8. [PMID: 26302930 DOI: 10.1016/j.jtemb.2015.06.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 06/23/2015] [Accepted: 06/29/2015] [Indexed: 11/25/2022]
Abstract
Organic mercury (Hg) species exert their toxicity primarily in the central nervous system. The food relevant Hg species methylmercury (MeHg) has been frequently studied regarding its neurotoxic effects in vitro and in vivo. Neurotoxicity of thiomersal, which is used as a preservative in medical preparations, is to date less characterised. Due to dealkylation of organic Hg or oxidation of elemental Hg, inorganic Hg is present in the brain albeit these species are not able to readily cross the blood brain barrier. This study compared for the first time toxic effects of organic MeHg chloride (MeHgCl) and thiomersal as well as inorganic mercury chloride (HgCl2) in differentiated human neurons (LUHMES) and human astrocytes (CCF-STTG1). The three Hg species differ in their degree and mechanism of toxicity in those two types of brain cells. Generally, neurons are more susceptible to Hg species induced cytotoxicity as compared to astrocytes. This might be due to the massive cellular mercury uptake in the differentiated neurons. The organic compounds exerted stronger cytotoxic effects as compared to inorganic HgCl2. In contrast to HgCl2 exposure, organic Hg compounds seem to induce the apoptotic cascade in neurons following low-level exposure. No indicators for apoptosis were identified for both inorganic and organic mercury species in astrocytes. Our studies clearly demonstrate species-specific toxic mechanisms. A mixed exposure towards all Hg species in the brain can be assumed. Thus, prospectively coexposure studies as well as cocultures of neurons and astrocytes could provide additional information in the investigation of Hg induced neurotoxicity.
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Affiliation(s)
- Hanna Lohren
- Department of Food Chemistry, Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114 - 116, 14558 Nuthetal, Germany.
| | - Lara Blagojevic
- Institute of Food Chemistry, University of Muenster, Corrensstraße 45, 48149 Muenster, Germany.
| | - Romy Fitkau
- Department of Food Chemistry, Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114 - 116, 14558 Nuthetal, Germany.
| | - Franziska Ebert
- Department of Food Chemistry, Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114 - 116, 14558 Nuthetal, Germany.
| | - Stefan Schildknecht
- Doerenkamp-Zbinden Chair of In Vitro Toxicology and Biomedicine, University of Konstanz, Universitaetsstraße 10, 78464 Konstanz, Germany.
| | - Marcel Leist
- Doerenkamp-Zbinden Chair of In Vitro Toxicology and Biomedicine, University of Konstanz, Universitaetsstraße 10, 78464 Konstanz, Germany.
| | - Tanja Schwerdtle
- Department of Food Chemistry, Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114 - 116, 14558 Nuthetal, Germany.
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Smirnova L, Hogberg HT, Leist M, Hartung T. Developmental neurotoxicity - challenges in the 21st century and in vitro opportunities. ALTEX-ALTERNATIVES TO ANIMAL EXPERIMENTATION 2015; 31:129-56. [PMID: 24687333 DOI: 10.14573/altex.1403271] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 03/28/2014] [Indexed: 11/23/2022]
Abstract
In recent years neurodevelopmental problems in children have increased at a rate that suggests lifestyle factors and chemical exposures as likely contributors. When environmental chemicals contribute to neurodevelopmental disorders developmental neurotoxicity (DNT) becomes an enormous concern. But how can it be tackled? Current animal test- based guidelines are prohibitively expensive, at $ 1.4 million per substance, while their predictivity for human health effects may be limited, and mechanistic data that would help species extrapolation are not available. A broader screening for substances of concern requires a reliable testing strategy, applicable to larger numbers of substances, and sufficiently predictive to warrant further testing. This review discusses the evidence for possible contributions of environmental chemicals to DNT, limitations of the current test paradigm, emerging concepts and technologies pertinent to in vitro DNT testing and assay evaluation, as well as the prospect of a paradigm shift based on 21st century technologies.
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Affiliation(s)
- Lena Smirnova
- Centers for Alternatives to Animal Testing (CAAT) at Johns Hopkins Bloomberg School of Public Health, USA
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30
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Using Pluripotent Stem Cells and Their Progeny as an In VitroModel to Assess (Developmental) Neurotoxicity. METHODS AND PRINCIPLES IN MEDICINAL CHEMISTRY 2014. [DOI: 10.1002/9783527674183.ch13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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31
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Silva-Pereira LC, da Rocha CAM, Cunha LRCDSE, da Costa ET, Guimarães APA, Pontes TB, Diniz DLWP, Leal MF, Moreira-Nunes CA, Burbano RR. Protective effect of prolactin against methylmercury-induced mutagenicity and cytotoxicity on human lymphocytes. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2014; 11:9822-34. [PMID: 25247425 PMCID: PMC4199052 DOI: 10.3390/ijerph110909822] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 09/04/2014] [Accepted: 09/10/2014] [Indexed: 01/19/2023]
Abstract
Mercury exhibits cytotoxic and mutagenic properties as a result of its effect on tubulin. This toxicity mechanism is related to the production of free radicals that can cause DNA damage. Methylmercury (MeHg) is one of the most toxic of the mercury compounds. It accumulates in the aquatic food chain, eventually reaching the human diet. Several studies have demonstrated that prolactin (PRL) may be differently affected by inorganic and organic mercury based on interference with various neurotransmitters involved in the regulation of PRL secretion. This study evaluated the cytoprotective effect of PRL on human lymphocytes exposed to MeHg in vitro, including observation of the kinetics of HL-60 cells (an acute myeloid leukemia lineage) treated with MeHg and PRL at different concentrations, with both treatments with the individual compounds and combined treatments. All treatments with MeHg produced a significant increase in the frequency of chromatid gaps, however, no significant difference was observed in the chromosomal breaks with any treatment. A dose-dependent increase in the mitotic index was observed for treatments with PRL, which also acts as a co-mitogenic factor, regulating proliferation by modulating the expression of genes that are essential for cell cycle progression and cytoskeleton organization. These properties contribute to the protective action of PRL against the cytotoxic and mutagenic effects of MeHg.
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Affiliation(s)
- Liz Carmem Silva-Pereira
- Federal Institute of Education, Science and Technology of Para, Itaituba Campus, IFPA Itaituba, Para 68180000, Brazil; E-Mail:
- Biological Science Institute, Federal University of Para, Belem, Para 66075110, Brazil; E-Mails: (L.R.C.S.C.Jr); (E.T.C.); (T.B.P.); (C.A.M.N.)
| | | | | | - Edmar Tavares da Costa
- Biological Science Institute, Federal University of Para, Belem, Para 66075110, Brazil; E-Mails: (L.R.C.S.C.Jr); (E.T.C.); (T.B.P.); (C.A.M.N.)
| | - Ana Paula Araújo Guimarães
- Center of Biological and Health Sciences, University of Para, Belem Campus UEPA, Belem, Para 66050540, Brazil; E-Mail:
| | - Thais Brilhante Pontes
- Biological Science Institute, Federal University of Para, Belem, Para 66075110, Brazil; E-Mails: (L.R.C.S.C.Jr); (E.T.C.); (T.B.P.); (C.A.M.N.)
| | | | - Mariana Ferreira Leal
- Department of Morphology and Genetics, Federal University of São Paulo, São Paulo 04021001 Brazil; E-Mail:
| | - Caroline Aquino Moreira-Nunes
- Biological Science Institute, Federal University of Para, Belem, Para 66075110, Brazil; E-Mails: (L.R.C.S.C.Jr); (E.T.C.); (T.B.P.); (C.A.M.N.)
| | - Rommel Rodríguez Burbano
- Biological Science Institute, Federal University of Para, Belem, Para 66075110, Brazil; E-Mails: (L.R.C.S.C.Jr); (E.T.C.); (T.B.P.); (C.A.M.N.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel: +55-91-3201-7102; Fax: +55-91-3201-7568
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32
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Differentiating neurons derived from human umbilical cord blood stem cells work as a test system for developmental neurotoxicity. Mol Neurobiol 2014; 51:791-807. [DOI: 10.1007/s12035-014-8716-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 04/11/2014] [Indexed: 01/19/2023]
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33
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Olioso D, Marzotto M, Moratti E, Brizzi M, Bellavite P. Effects of Gelsemium sempervirens L. on pathway-focused gene expression profiling in neuronal cells. JOURNAL OF ETHNOPHARMACOLOGY 2014; 153:535-539. [PMID: 24613275 DOI: 10.1016/j.jep.2014.02.048] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/10/2014] [Accepted: 02/15/2014] [Indexed: 06/03/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Gelsemium sempervirens L. is a traditional medicinal plant mainly distributed in the southeastern of the United States, employed in phytotheraphy and homeopathy as nervous system relaxant to treat various types of anxiety, pain, headache and other ailments. Although animal models showed its effectiveness, the mechanisms by which it might operate on the nervous system are largely unknown. This study investigated for the first time by a real-time PCR technique (RT-PCR Array) the gene expression of a panel of human neurotransmitter receptors and regulators, involved in neuronal excitatory signaling, on a neurocyte cell line. MATERIALS AND METHODS Human SH-SY5Y neuroblastoma cells were exposed for 24h to Gelsemium sempervirens at 2c and 9c dilutions (i.e. 2 and 9-fold centesimal dilutions from mother tincture) and the gene expression profile compared to that of cells treated with control vehicle solutions. RESULTS Exposure to the Gelsemium sempervirens 2c dilution, containing a nanomolar concentration of active principle gelsemine, induced a down-regulation of most genes of this array. In particular, the treated cells showed a statistically significant decrease of the prokineticin receptor 2, whose ligand is a neuropeptide involved in nociception, anxiety and depression-like behavior. CONCLUSIONS Overall, the results indicate a negative modulation trend in neuronal excitatory signaling, which can suggest new working hypotheses on the anxiolytic and analgesic action of this plant.
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Affiliation(s)
- Debora Olioso
- Department of Pathology and Diagnostics, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy.
| | - Marta Marzotto
- Department of Pathology and Diagnostics, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy.
| | - Elisabetta Moratti
- Department of Pathology and Diagnostics, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy.
| | - Maurizio Brizzi
- Department of Statistical Sciences, University of Bologna, Via delle Belle Arti 41, 40126 Bologna, Italy.
| | - Paolo Bellavite
- Department of Pathology and Diagnostics, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy.
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Zimmer B, Pallocca G, Dreser N, Foerster S, Waldmann T, Westerhout J, Julien S, Krause KH, van Thriel C, Hengstler JG, Sachinidis A, Bosgra S, Leist M. Profiling of drugs and environmental chemicals for functional impairment of neural crest migration in a novel stem cell-based test battery. Arch Toxicol 2014; 88:1109-26. [PMID: 24691702 PMCID: PMC3996367 DOI: 10.1007/s00204-014-1231-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/18/2014] [Indexed: 11/28/2022]
Abstract
Developmental toxicity in vitro assays have hitherto been established as stand-alone systems, based on a limited number of toxicants. Within the embryonic stem cell-based novel alternative tests project, we developed a test battery framework that allows inclusion of any developmental toxicity assay and that explores the responses of such test systems to a wide range of drug-like compounds. We selected 28 compounds, including several biologics (e.g., erythropoietin), classical pharmaceuticals (e.g., roflumilast) and also six environmental toxicants. The chemical, toxicological and clinical data of this screen library were compiled. In order to determine a non-cytotoxic concentration range, cytotoxicity data were obtained for all compounds from HEK293 cells and from murine embryonic stem cells. Moreover, an estimate of relevant exposures was provided by literature data mining. To evaluate feasibility of the suggested test framework, we selected a well-characterized assay that evaluates ‘migration inhibition of neural crest cells.’ Screening at the highest non-cytotoxic concentration resulted in 11 hits (e.g., geldanamycin, abiraterone, gefitinib, chlorpromazine, cyproconazole, arsenite). These were confirmed in concentration–response studies. Subsequent pharmacokinetic modeling indicated that triadimefon exerted its effects at concentrations relevant to the in vivo situation, and also interferon-β and polybrominated diphenyl ether showed effects within the same order of magnitude of concentrations that may be reached in humans. In conclusion, the test battery framework can identify compounds that disturb processes relevant for human development and therefore may represent developmental toxicants. The open structure of the strategy allows rich information to be generated on both the underlying library, and on any contributing assay.
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Affiliation(s)
- B Zimmer
- Center for Stem Cell Biology, Sloan-Kettering Institute for Cancer Research, New York City, NY, USA
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Balmer NV, Leist M. Epigenetics and transcriptomics to detect adverse drug effects in model systems of human development. Basic Clin Pharmacol Toxicol 2014; 115:59-68. [PMID: 24476462 DOI: 10.1111/bcpt.12203] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 01/16/2014] [Indexed: 01/01/2023]
Abstract
Prenatal exposure to environmental chemicals or drugs has been associated with functional or structural deficits and the development of diseases in later life. For example, developmental neurotoxicity (DNT) is triggered by lead, and this compound may predispose to neurodegenerative diseases in later life. The molecular memory for such late consequences of early exposure is not known, but epigenetic mechanisms (modification of the chromatin structure) could take this role. Examples and underlying mechanisms have been compiled here for the field of DNT. Moreover, we addressed the question as to what readout is suitable for addressing drug memory effects. We summarize how complex developmental processes can be modelled in vitro by using the differentiation of human stem cells. Although cellular models can never replicate the final human DNT phenotype, they can model the adverse effect that a chemical has on key biological processes essential for organ formation and function. Highly information-rich transcriptomics data may inform on these changes and form the bridge from in vitro models to human prediction. We compiled data showing that transcriptome analysis can indicate toxicity patterns of drugs. A crucial question to be answered in our systems is when and how transcriptome changes indicate adversity (as opposed to transient adaptive responses), and how drug-induced changes are perpetuated over time even after washout of the drug. We present evidence for the hypothesis that changes in the histone methylation pattern could represent the persistence detector of an early insult that is transformed to an adverse effect at later time-points in life.
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Affiliation(s)
- Nina V Balmer
- Doerenkamp-Zbinden Chair for In Vitro Toxicology and Biomedicine, University of Konstanz, Konstanz, Germany
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Waldmann T, Rempel E, Balmer NV, König A, Kolde R, Gaspar JA, Henry M, Hescheler J, Sachinidis A, Rahnenführer J, Hengstler JG, Leist M. Design principles of concentration-dependent transcriptome deviations in drug-exposed differentiating stem cells. Chem Res Toxicol 2014; 27:408-20. [PMID: 24383497 PMCID: PMC3958134 DOI: 10.1021/tx400402j] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
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Information on design principles
governing transcriptome changes
upon transition from safe to hazardous drug concentrations or from
tolerated to cytotoxic drug levels are important for the application
of toxicogenomics data in developmental toxicology. Here, we tested
the effect of eight concentrations of valproic acid (VPA; 25–1000
μM) in an assay that recapitulates the development of human
embryonic stem cells to neuroectoderm. Cells were exposed to the drug
during the entire differentiation process, and the number of differentially
regulated genes increased continuously over the concentration range
from zero to about 3000. We identified overrepresented transcription
factor binding sites (TFBS) as well as superordinate cell biological
processes, and we developed a gene ontology (GO) activation profiler,
as well as a two-dimensional teratogenicity index. Analysis of the
transcriptome data set by the above biostatistical and systems biology
approaches yielded the following insights: (i) tolerated (≤25
μM), deregulated/teratogenic (150–550 μM), and
cytotoxic (≥800 μM) concentrations could be differentiated.
(ii) Biological signatures related to the mode of action of VPA, such
as protein acetylation, developmental changes, and cell migration,
emerged from the teratogenic concentrations range. (iii) Cytotoxicity
was not accompanied by signatures of newly emerging canonical cell
death/stress indicators, but by catabolism and decreased expression
of cell cycle associated genes. (iv) Most, but not all of the GO groups
and TFBS seen at the highest concentrations were already overrepresented
at 350–450 μM. (v) The teratogenicity index reflected
this behavior, and thus differed strongly from cytotoxicity. Our findings
suggest the use of the highest noncytotoxic drug concentration for
gene array toxicogenomics studies, as higher concentrations possibly
yield wrong information on the mode of action, and lower drug levels
result in decreased gene expression changes and thus a reduced power
of the study.
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Affiliation(s)
- Tanja Waldmann
- Doerenkamp-Zbinden Chair for in Vitro Toxicology and Biomedicine, University of Konstanz , 78457 Konstanz, Germany
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Mori H, Hara M. Cultured stem cells as tools for toxicological assays. J Biosci Bioeng 2013; 116:647-52. [DOI: 10.1016/j.jbiosc.2013.05.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 05/17/2013] [Accepted: 05/20/2013] [Indexed: 12/29/2022]
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Martinez-Finley EJ, Caito S, Slaughter JC, Aschner M. The Role of skn-1 in methylmercury-induced latent dopaminergic neurodegeneration. Neurochem Res 2013; 38:2650-60. [PMID: 24194349 DOI: 10.1007/s11064-013-1183-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/09/2013] [Accepted: 10/17/2013] [Indexed: 02/07/2023]
Abstract
Mercury (Hg) is a persistent environmental bioaccumulative metal, with developmental exposure to methylmercury (MeHg) resulting in long-term health effects. We examined the impact of early-life exposure to MeHg and knockdown of skn-1 on dopaminergic (DAergic) neurodegeneration in the nematode Caenorhabditis elegans. SKN-1, a the major stress-activated cytoprotective transcription factors, promotes the transcription of enzymes that scavenge free radicals, synthesizes glutathione and catalyzes reactions that increase xenobiotic excretion. Deletions or mutations in this gene suppress stress resistance. Thus, we hypothesized that the extent of MeHg's toxicity is dependent on intact skn-1 response; therefore skn-1 knockout (KO) worms would show heightened sensitivity to MeHg-induced toxicity compared to wildtype worms. In this study we identified the impact of early-life MeHg exposure on Hg content, stress reactivity and DAergic neurodegeneration in wildtype, and skn-1KO C. elegans. Hg content, measured by Inductively Coupled Plasma Mass Spectrometry, showed no strain-dependent differences. Reactive oxygen species generation was dramatically increased in skn-1KO compared to wildtype worms. Structural integrity of DAergic neurons was microscopically assessed by visualization of fluorescently-labeled neurons, and revealed loss of neurons in skn-1KO and MeHg exposed worms compared to wildtype controls. Dopamine levels detected by High-performance liquid chromatography, were decreased in response to MeHg exposure and decreased in skn-1KO worms, and functional behavioral assays showed similar findings. Combined, these studies suggest that knockdown of skn-1 in the nematode increases DAergic sensitivity to MeHg exposure following a period of latency.
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Affiliation(s)
- Ebany J Martinez-Finley
- Division of Pediatric Toxicology and Clinical Pharmacology, Vanderbilt University Medical Center, 11425 MRB IV, 2215-B Garland Ave., Nashville, TN, 37232-0414, USA
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Krause KH, van Thriel C, De Sousa PA, Leist M, Hengstler JG. Monocrotophos in Gandaman village: India school lunch deaths and need for improved toxicity testing. Arch Toxicol 2013; 87:1877-81. [PMID: 23943209 DOI: 10.1007/s00204-013-1113-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 08/01/2013] [Indexed: 12/22/2022]
Affiliation(s)
- Karl-Heinz Krause
- Department of Pathology and Immunology, Geneva Medical Faculty, Centre Medical Universitaire, University of Geneva (UNIGE), 1, rue Michel-Servet, 1211, Geneva 4, Switzerland,
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Farina M, Avila DS, da Rocha JBT, Aschner M. Metals, oxidative stress and neurodegeneration: a focus on iron, manganese and mercury. Neurochem Int 2012; 62:575-94. [PMID: 23266600 DOI: 10.1016/j.neuint.2012.12.006] [Citation(s) in RCA: 357] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Revised: 12/07/2012] [Accepted: 12/10/2012] [Indexed: 02/08/2023]
Abstract
Essential metals are crucial for the maintenance of cell homeostasis. Among the 23 elements that have known physiological functions in humans, 12 are metals, including iron (Fe) and manganese (Mn). Nevertheless, excessive exposure to these metals may lead to pathological conditions, including neurodegeneration. Similarly, exposure to metals that do not have known biological functions, such as mercury (Hg), also present great health concerns. This review focuses on the neurodegenerative mechanisms and effects of Fe, Mn and Hg. Oxidative stress (OS), particularly in mitochondria, is a common feature of Fe, Mn and Hg toxicity. However, the primary molecular targets triggering OS are distinct. Free cationic iron is a potent pro-oxidant and can initiate a set of reactions that form extremely reactive products, such as OH. Mn can oxidize dopamine (DA), generating reactive species and also affect mitochondrial function, leading to accumulation of metabolites and culminating with OS. Cationic Hg forms have strong affinity for nucleophiles, such as -SH and -SeH. Therefore, they target critical thiol- and selenol-molecules with antioxidant properties. Finally, we address the main sources of exposure to these metals, their transport mechanisms into the brain, and therapeutic modalities to mitigate their neurotoxic effects.
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Affiliation(s)
- Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil
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Hoelting L, Scheinhardt B, Bondarenko O, Schildknecht S, Kapitza M, Tanavde V, Tan B, Lee QY, Mecking S, Leist M, Kadereit S. A 3-dimensional human embryonic stem cell (hESC)-derived model to detect developmental neurotoxicity of nanoparticles. Arch Toxicol 2012. [PMID: 23203475 PMCID: PMC3604581 DOI: 10.1007/s00204-012-0984-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Nanoparticles (NPs) have been shown to accumulate in organs, cross the blood-brain barrier and placenta, and have the potential to elicit developmental neurotoxicity (DNT). Here, we developed a human embryonic stem cell (hESC)-derived 3-dimensional (3-D) in vitro model that allows for testing of potential developmental neurotoxicants. Early central nervous system PAX6(+) precursor cells were generated from hESCs and differentiated further within 3-D structures. The 3-D model was characterized for neural marker expression revealing robust differentiation toward neuronal precursor cells, and gene expression profiling suggested a predominantly forebrain-like development. Altered neural gene expression due to exposure to non-cytotoxic concentrations of the known developmental neurotoxicant, methylmercury, indicated that the 3-D model could detect DNT. To test for specific toxicity of NPs, chemically inert polyethylene NPs (PE-NPs) were chosen. They penetrated deep into the 3-D structures and impacted gene expression at non-cytotoxic concentrations. NOTCH pathway genes such as HES5 and NOTCH1 were reduced in expression, as well as downstream neuronal precursor genes such as NEUROD1 and ASCL1. FOXG1, a patterning marker, was also reduced. As loss of function of these genes results in severe nervous system impairments in mice, our data suggest that the 3-D hESC-derived model could be used to test for Nano-DNT.
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Affiliation(s)
- Lisa Hoelting
- Department of Biology, University of Konstanz, Universitaetsstrasse 10, 78457 Konstanz, Germany
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Bolt HM. Developmental neurotoxicity testing with human embryonic stem cell-derived in vitro systems: the novel FP7 ESNATS tests are available. Arch Toxicol 2012. [DOI: 10.1007/s00204-012-0982-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Krug AK, Kolde R, Gaspar JA, Rempel E, Balmer NV, Meganathan K, Vojnits K, Baquié M, Waldmann T, Ensenat-Waser R, Jagtap S, Evans RM, Julien S, Peterson H, Zagoura D, Kadereit S, Gerhard D, Sotiriadou I, Heke M, Natarajan K, Henry M, Winkler J, Marchan R, Stoppini L, Bosgra S, Westerhout J, Verwei M, Vilo J, Kortenkamp A, Hescheler J, Hothorn L, Bremer S, van Thriel C, Krause KH, Hengstler JG, Rahnenführer J, Leist M, Sachinidis A. Human embryonic stem cell-derived test systems for developmental neurotoxicity: a transcriptomics approach. Arch Toxicol 2012. [PMID: 23179753 PMCID: PMC3535399 DOI: 10.1007/s00204-012-0967-3] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Developmental neurotoxicity (DNT) and many forms of reproductive toxicity (RT) often manifest themselves in functional deficits that are not necessarily based on cell death, but rather on minor changes relating to cell differentiation or communication. The fields of DNT/RT would greatly benefit from in vitro tests that allow the identification of toxicant-induced changes of the cellular proteostasis, or of its underlying transcriptome network. Therefore, the ‘human embryonic stem cell (hESC)-derived novel alternative test systems (ESNATS)’ European commission research project established RT tests based on defined differentiation protocols of hESC and their progeny. Valproic acid (VPA) and methylmercury (MeHg) were used as positive control compounds to address the following fundamental questions: (1) Does transcriptome analysis allow discrimination of the two compounds? (2) How does analysis of enriched transcription factor binding sites (TFBS) and of individual probe sets (PS) distinguish between test systems? (3) Can batch effects be controlled? (4) How many DNA microarrays are needed? (5) Is the highest non-cytotoxic concentration optimal and relevant for the study of transcriptome changes? VPA triggered vast transcriptional changes, whereas MeHg altered fewer transcripts. To attenuate batch effects, analysis has been focused on the 500 PS with highest variability. The test systems differed significantly in their responses (<20 % overlap). Moreover, within one test system, little overlap between the PS changed by the two compounds has been observed. However, using TFBS enrichment, a relatively large ‘common response’ to VPA and MeHg could be distinguished from ‘compound-specific’ responses. In conclusion, the ESNATS assay battery allows classification of human DNT/RT toxicants on the basis of their transcriptome profiles.
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Affiliation(s)
- Anne K. Krug
- Department of Biology, University of Konstanz (UKN), 78457 Constance, Germany
| | - Raivo Kolde
- OÜ Quretec (Qure), Limited Liability Company, 51003 Tartu, Estonia
- Institute of Computer Science, University of Tartu, 50409 Tartu, Estonia
| | - John A. Gaspar
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Eugen Rempel
- Department of Statistics, TU Dortmund University , 44221 Dortmund, Germany
| | - Nina V. Balmer
- Department of Biology, University of Konstanz (UKN), 78457 Constance, Germany
| | - Kesavan Meganathan
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Kinga Vojnits
- Commission of the European Communities (JRC) Joint Research Centre, 1049 Brussels, Belgium
| | - Mathurin Baquié
- Department of Pathology and Immunology, Geneva Medical Faculty, University of Geneva (UNIGE), 1211 Geneva 4, Switzerland
| | - Tanja Waldmann
- Department of Biology, University of Konstanz (UKN), 78457 Constance, Germany
| | - Roberto Ensenat-Waser
- Commission of the European Communities (JRC) Joint Research Centre, 1049 Brussels, Belgium
| | - Smita Jagtap
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
| | | | - Stephanie Julien
- Department of Pathology and Immunology, Geneva Medical Faculty, University of Geneva (UNIGE), 1211 Geneva 4, Switzerland
| | - Hedi Peterson
- Department of Pathology and Immunology, Geneva Medical Faculty, University of Geneva (UNIGE), 1211 Geneva 4, Switzerland
| | - Dimitra Zagoura
- Commission of the European Communities (JRC) Joint Research Centre, 1049 Brussels, Belgium
| | - Suzanne Kadereit
- Department of Biology, University of Konstanz (UKN), 78457 Constance, Germany
| | - Daniel Gerhard
- Gottfried Wilhelm Leibniz University (LUH), Institute for Biostatistics, 30167 Hannover, Germany
| | - Isaia Sotiriadou
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Michael Heke
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Karthick Natarajan
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Margit Henry
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Johannes Winkler
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Rosemarie Marchan
- Leibniz Research Centre for Working Environment and Human Factors (IfADo), Technical University of Dortmund, 44139 Dortmund, Germany
| | - Luc Stoppini
- Department of Pathology and Immunology, Geneva Medical Faculty, University of Geneva (UNIGE), 1211 Geneva 4, Switzerland
| | - Sieto Bosgra
- Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (TNO), 2628 VK Delft, The Netherlands
| | - Joost Westerhout
- Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (TNO), 2628 VK Delft, The Netherlands
| | - Miriam Verwei
- Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (TNO), 2628 VK Delft, The Netherlands
| | - Jaak Vilo
- OÜ Quretec (Qure), Limited Liability Company, 51003 Tartu, Estonia
- Institute of Computer Science, University of Tartu, 50409 Tartu, Estonia
| | | | - Jürgen Hescheler
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Ludwig Hothorn
- Gottfried Wilhelm Leibniz University (LUH), Institute for Biostatistics, 30167 Hannover, Germany
| | - Susanne Bremer
- Commission of the European Communities (JRC) Joint Research Centre, 1049 Brussels, Belgium
| | - Christoph van Thriel
- Leibniz Research Centre for Working Environment and Human Factors (IfADo), Technical University of Dortmund, 44139 Dortmund, Germany
| | - Karl-Heinz Krause
- Department of Pathology and Immunology, Geneva Medical Faculty, University of Geneva (UNIGE), 1211 Geneva 4, Switzerland
| | - Jan G. Hengstler
- Leibniz Research Centre for Working Environment and Human Factors (IfADo), Technical University of Dortmund, 44139 Dortmund, Germany
| | - Jörg Rahnenführer
- Department of Statistics, TU Dortmund University , 44221 Dortmund, Germany
| | - Marcel Leist
- Department of Biology, University of Konstanz (UKN), 78457 Constance, Germany
| | - Agapios Sachinidis
- Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne (UKK), Robert-Koch-Str. 39, 50931 Cologne, Germany
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Qin XY, Akanuma H, Wei F, Nagano R, Zeng Q, Imanishi S, Ohsako S, Yoshinaga J, Yonemoto J, Tanokura M, Sone H. Effect of low-dose thalidomide on dopaminergic neuronal differentiation of human neural progenitor cells: a combined study of metabolomics and morphological analysis. Neurotoxicology 2012; 33:1375-80. [PMID: 22981892 DOI: 10.1016/j.neuro.2012.08.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 08/29/2012] [Accepted: 08/31/2012] [Indexed: 02/04/2023]
Abstract
Thalidomide is increasingly used in anticancer and anti-inflammation therapies. However, it is known for its teratogenicity and ability to induce peripheral neuropathy, although the mechanisms underlying its neurological effect in humans are unclear. In this study, we investigated the effect of thalidomide on the metabolism and neuronal differentiation of human neural progenitor cells. We found that levels of tyrosine, phenylalanine, methionine and glutathione, which are involved in dopamine and methionine metabolism, were decreased following thalidomide treatment. Morphological analysis revealed that treatment with 100 nM thalidomide, which is much lower than clinical doses, significantly decreased the number of dopaminergic (tyrosine hydroxylase-positive) neurons, compared with control cells. Our results suggest that these adverse neurological effects of thalidomide should be taken into consideration prior to its use for the treatment of neurodegenerative and other diseases.
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Affiliation(s)
- Xian-Yang Qin
- Health Risk Research Section, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8606, Japan
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Zimmer B, Lee G, Balmer NV, Meganathan K, Sachinidis A, Studer L, Leist M. Evaluation of developmental toxicants and signaling pathways in a functional test based on the migration of human neural crest cells. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:1116-1122. [PMID: 22571897 PMCID: PMC3440079 DOI: 10.1289/ehp.1104489] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 05/09/2012] [Indexed: 05/31/2023]
Abstract
BACKGROUND Information on the potential developmental toxicity (DT) of the majority of chemicals is scarce, and test capacities for further animal-based testing are limited. Therefore, new approaches with higher throughput are required. A screening strategy based on the use of relevant human cell types has been proposed by the U.S. Environmental Protection Agency and others. Because impaired neural crest (NC) function is one of the known causes for teratologic effects, testing of toxicant effects on NC cells is desirable for a DT test battery. OBJECTIVE We developed a robust and widely applicable human-relevant NC function assay that would allow for sensitive screening of environmental toxicants and defining toxicity pathways. METHODS We generated NC cells from human embryonic stem cells, and after establishing a migration assay of NC cells (MINC assay), we tested environmental toxicants as well as inhibitors of physiological signal transduction pathways. RESULTS Methylmercury (50 nM), valproic acid (> 10 µM), and lead-acetate [Pb(CH3CO2)4] (1 µM) affected the migration of NC cells more potently than migration of other cell types. The MINC assay correctly identified the NC toxicants triadimefon and triadimenol. Additionally, it showed different sensitivities to various organic and inorganic mercury compounds. Using the MINC assay and applying classic pharmacologic inhibitors and large-scale microarray gene expression profiling, we found several signaling pathways that are relevant for the migration of NC cells. CONCLUSIONS The MINC assay faithfully models human NC cell migration, and it reveals impairment of this function by developmental toxicants with good sensitivity and specificity.
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Affiliation(s)
- Bastian Zimmer
- Doerenkamp-Zbinden Chair of In Vitro Toxicology and Biomedicine, University of Konstanz, Konstanz, Germany
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Balmer NV, Weng MK, Zimmer B, Ivanova VN, Chambers SM, Nikolaeva E, Jagtap S, Sachinidis A, Hescheler J, Waldmann T, Leist M. Epigenetic changes and disturbed neural development in a human embryonic stem cell-based model relating to the fetal valproate syndrome. Hum Mol Genet 2012; 21:4104-14. [DOI: 10.1093/hmg/dds239] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Leist M, Hasiwa N, Daneshian M, Hartung T. Validation and quality control of replacement alternatives – current status and future challenges. Toxicol Res (Camb) 2012. [DOI: 10.1039/c2tx20011b] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Abstract
Alternatives to animal testing have been developed mainly in the fields of toxicology and vaccine testing. Typical examples are the evaluation of phototoxicity, eye irritation or skin corrosion/irritation of cosmetics and industrial chemicals. However, examples can also be found in other biomedical areas, such the control of the quality of drug preparations for pyrogens or for the control of the production process of biologics, such as botulinum neurotoxin. For regulatory purposes, the quality, transferability and predictivity of an alternative method needs to be evaluated. This procedure is called the “validation process” of a new method. It follows defined rules, and several governmental institutions have been established to perform, supervise or advise on this process. As this often results in a delay of method implementation, different alternatives for the evaluation of a method's suitability and quality are under discussion. We describe here the principles of model development and quality control. We also give an overview on methods that have undergone validation. Strengths and shortcomings of traditional approaches are discussed, and new developments and challenges are outlined.
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Affiliation(s)
- Marcel Leist
- Doerenkamp-Zbinden Chair for In-vitro Toxicology and Biomedicine and Center for Alternatives to Animal Testing in Europe (CAAT-Europe), University of Konstanz, D-78467 Konstanz, Germany
| | - Nina Hasiwa
- Doerenkamp-Zbinden Chair for In-vitro Toxicology and Biomedicine and Center for Alternatives to Animal Testing in Europe (CAAT-Europe), University of Konstanz, D-78467 Konstanz, Germany
| | - Mardas Daneshian
- Doerenkamp-Zbinden Chair for In-vitro Toxicology and Biomedicine and Center for Alternatives to Animal Testing in Europe (CAAT-Europe), University of Konstanz, D-78467 Konstanz, Germany
| | - Thomas Hartung
- Doerenkamp-Zbinden Chair for In-vitro Toxicology and Biomedicine and Center for Alternatives to Animal Testing in Europe (CAAT-Europe), University of Konstanz, D-78467 Konstanz, Germany
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Fretham SJ, Caito S, Martinez-Finley EJ, Aschner M. Mechanisms and Modifiers of Methylmercury-Induced Neurotoxicity. Toxicol Res (Camb) 2012; 1:32-38. [PMID: 27795823 DOI: 10.1039/c2tx20010d] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The neurotoxic consequences of methylmercury (MeHg) exposure have long been known, however a complete understanding of the mechanisms underlying this toxicity is elusive. Recent epidemiological and experimental studies have provided many mechanistic insights, particularly into the contribution of genetic and environmental factors that interact with MeHg to modify toxicity. This review will outline cellular processes directly and indirectly affected by MeHg, including oxidative stress, cellular signaling and gene expression, and discuss genetic, environmental and nutritional factors capable of modifying MeHg toxicity.
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Affiliation(s)
- Stephanie Jb Fretham
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Samuel Caito
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Ebany J Martinez-Finley
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael Aschner
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
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Louisse J, Verwei M, Woutersen RA, Blaauboer BJ, Rietjens IMCM. Towardin vitrobiomarkers for developmental toxicity and their extrapolation to thein vivosituation. Expert Opin Drug Metab Toxicol 2011; 8:11-27. [DOI: 10.1517/17425255.2012.639762] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Farina M, Aschner M, Rocha JBT. Oxidative stress in MeHg-induced neurotoxicity. Toxicol Appl Pharmacol 2011; 256:405-17. [PMID: 21601588 PMCID: PMC3166649 DOI: 10.1016/j.taap.2011.05.001] [Citation(s) in RCA: 241] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 05/01/2011] [Accepted: 05/02/2011] [Indexed: 12/20/2022]
Abstract
Methylmercury (MeHg) is an environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. Although the molecular mechanisms mediating MeHg-induced neurotoxicity are not completely understood, several lines of evidence indicate that oxidative stress represents a critical event related to the neurotoxic effects elicited by this toxicant. The objective of this review is to summarize and discuss data from experimental and epidemiological studies that have been important in clarifying the molecular events which mediate MeHg-induced oxidative damage and, consequently, toxicity. Although unanswered questions remain, the electrophilic properties of MeHg and its ability to oxidize thiols have been reported to play decisive roles to the oxidative consequences observed after MeHg exposure. However, a close examination of the relationship between low levels of MeHg necessary to induce oxidative stress and the high amounts of sulfhydryl-containing antioxidants in mammalian cells (e.g., glutathione) have led to the hypothesis that nucleophilic groups with extremely high affinities for MeHg (e.g., selenols) might represent primary targets in MeHg-induced oxidative stress. Indeed, the inhibition of antioxidant selenoproteins during MeHg poisoning in experimental animals has corroborated this hypothesis. The levels of different reactive species (superoxide anion, hydrogen peroxide and nitric oxide) have been reported to be increased in MeHg-exposed systems, and the mechanisms concerning these increments seem to involve a complex sequence of cascading molecular events, such as mitochondrial dysfunction, excitotoxicity, intracellular calcium dyshomeostasis and decreased antioxidant capacity. This review also discusses potential therapeutic strategies to counteract MeHg-induced toxicity and oxidative stress, emphasizing the use of organic selenocompounds, which generally present higher affinity for MeHg when compared to the classically studied agents.
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Affiliation(s)
- Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Michael Aschner
- Department of Pediatrics and Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - João B. T. Rocha
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
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