1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Rajendran P, Al-Saeedi FJ, Ammar RB, Abdallah BM, Ali EM, Al Abdulsalam NK, Tejavat S, Althumairy D, Veeraraghavan VP, Alamer SA, Bekhet GM, Ahmed EA. Geraniol attenuates oxidative stress and neuroinflammation-mediated cognitive impairment in D galactose-induced mouse aging model. Aging (Albany NY) 2024; 16:5000-5026. [PMID: 38517361 PMCID: PMC11006477 DOI: 10.18632/aging.205677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 02/13/2024] [Indexed: 03/23/2024]
Abstract
D-galactose (D-gal) administration was proven to induce cognitive impairment and aging in rodents' models. Geraniol (GNL) belongs to the acyclic isoprenoid monoterpenes. GNL reduces inflammation by changing important signaling pathways and cytokines, and thus it is plausible to be used as a medicine for treating disorders linked to inflammation. Herein, we examined the therapeutic effects of GNL on D-gal-induced oxidative stress and neuroinflammation-mediated memory loss in mice. The study was conducted using six groups of mice (6 mice per group). The first group received normal saline, then D-gal (150 mg/wt) dissolved in normal saline solution (0.9%, w/v) was given orally for 9 weeks to the second group. In the III group, from the second week until the 10th week, mice were treated orally (without anesthesia) with D-gal (150 mg/kg body wt) and GNL weekly twice (40 mg/kg body wt) four hours later. Mice in Group IV were treated with GNL from the second week up until the end of the experiment. For comparison of young versus elderly mice, 4 month old (Group V) and 16-month-old (Group VI) control mice were used. We evaluated the changes in antioxidant levels, PI3K/Akt levels, and Nrf2 levels. We also examined how D-gal and GNL treated pathological aging changes. Administration of GNL induced a significant increase in spatial learning and memory with spontaneously altered behavior. Enhancing anti-oxidant and anti-inflammatory effects and activating PI3K/Akt were the mechanisms that mediated this effect. Further, GNL treatment upregulated Nrf2 and HO-1 to reduce oxidative stress and apoptosis. This was confirmed using 99mTc-HMPAO brain flow gamma bioassays. Thus, our data suggested GNL as a promising agent for treating neuroinflammation-induced cognitive impairment.
Collapse
Affiliation(s)
- Peramaiyan Rajendran
- Department of Biological Sciences, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
- Department of Biochemistry, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Chennai 600077, Tamil Nadu, India
| | - Fatma J. Al-Saeedi
- Department of Nuclear Medicine, College of Medicine, Kuwait University, Safat 13110, Kuwait
| | - Rebai Ben Ammar
- Department of Biological Sciences, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
- Laboratory of Aromatic and Medicinal Plants, Center of Biotechnology of Borj-Cedria, Technopole of Borj-Cedria PBOX 901, Hammam-Lif 2050, Tunisia
| | - Basem M. Abdallah
- Department of Biological Sciences, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Enas M. Ali
- Department of Biological Sciences, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Najla Khaled Al Abdulsalam
- Department of Biological Sciences, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Sujatha Tejavat
- Department of Biomedical Sciences, College of Medicine, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Duaa Althumairy
- Department of Biological Sciences, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Vishnu Priya Veeraraghavan
- Department of Biochemistry, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Chennai 600077, Tamil Nadu, India
| | - Sarah Abdulaziz Alamer
- Department of Biological Sciences, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Gamal M. Bekhet
- Department of Biological Sciences, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
- Department of Zoology, Faculty of Science, Alexandria University Egypt, Alexandria 21544, Egypt
| | - Emad A. Ahmed
- Department of Biological Sciences, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
- Laboratory of Molecular Physiology, Zoology Department, Faculty of Science, Assiut University, Assiut 71515, Egypt
| |
Collapse
|
3
|
Everman ER, Macdonald SJ. Gene expression variation underlying tissue-specific responses to copper stress in Drosophila melanogaster. G3 (BETHESDA, MD.) 2024; 14:jkae015. [PMID: 38262701 PMCID: PMC11021028 DOI: 10.1093/g3journal/jkae015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 01/04/2024] [Accepted: 01/08/2024] [Indexed: 01/25/2024]
Abstract
Copper is one of a handful of biologically necessary heavy metals that is also a common environmental pollutant. Under normal conditions, copper ions are required for many key physiological processes. However, in excess, copper results in cell and tissue damage ranging in severity from temporary injury to permanent neurological damage. Because of its biological relevance, and because many conserved copper-responsive genes respond to nonessential heavy metal pollutants, copper resistance in Drosophila melanogaster is a useful model system with which to investigate the genetic control of the heavy metal stress response. Because heavy metal toxicity has the potential to differently impact specific tissues, we genetically characterized the control of the gene expression response to copper stress in a tissue-specific manner in this study. We assessed the copper stress response in head and gut tissue of 96 inbred strains from the Drosophila Synthetic Population Resource using a combination of differential expression analysis and expression quantitative trait locus mapping. Differential expression analysis revealed clear patterns of tissue-specific expression. Tissue and treatment specific responses to copper stress were also detected using expression quantitative trait locus mapping. Expression quantitative trait locus associated with MtnA, Mdr49, Mdr50, and Sod3 exhibited both genotype-by-tissue and genotype-by-treatment effects on gene expression under copper stress, illuminating tissue- and treatment-specific patterns of gene expression control. Together, our data build a nuanced description of the roles and interactions between allelic and expression variation in copper-responsive genes, provide valuable insight into the genomic architecture of susceptibility to metal toxicity, and highlight candidate genes for future functional characterization.
Collapse
Affiliation(s)
- Elizabeth R Everman
- School of Biological Sciences, The University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA
| | - Stuart J Macdonald
- Molecular Biosciences, University of Kansas, 1200 Sunnyside Ave, Lawrence, KS 66045, USA
| |
Collapse
|
4
|
de Paula HK, Love TM, Pineda D, Watson GE, Thurston SW, Yeates AJ, Mulhern MS, McSorley EM, Strain JJ, Shamlaye CF, Myers GJ, Rand MD, van Wijngaarden E, Broberg K. KEAP1 polymorphisms and neurodevelopmental outcomes in children with exposure to prenatal MeHg from the Seychelles Child Development Study Nutrition Cohort 2. Neurotoxicology 2023; 99:177-183. [PMID: 37858899 PMCID: PMC10841683 DOI: 10.1016/j.neuro.2023.10.008] [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: 06/30/2023] [Revised: 09/25/2023] [Accepted: 10/14/2023] [Indexed: 10/21/2023]
Abstract
BACKGROUND Humans differ in the metabolism of the neurotoxicant methyl mercury (MeHg). This variation may be partially due to variation in genes encoding the transcription factor Nuclear factor E2-related factor 2 (NRF2) and its negative regulator Kelch-like ECH-Associated Protein 1 (KEAP1), which regulate glutathione and related transporter and antioxidant proteins that play a role in the metabolism and neurotoxicity of MeHg. AIM To elucidate a potential risk from genetic variation in NFE2L2 (encoding NRF2) and KEAP1 toward prenatal mercury exposure and child neurodevelopmental outcomes at 20 months and 7 years of age in a population with variable prenatal exposure to MeHg from maternal fish consumption. MATERIAL AND METHODS Nutrition Cohort 2 is a mother-child cohort in the Republic of Seychelles. Children were genotyped for NFE2L2 (rs2364723, rs13001694) and KEAP1 (rs8113472, rs9676881) polymorphisms (N = 1285 after removing siblings). Total mercury (Hg) was measured in cord blood as a biomarker for prenatal MeHg exposure. Child neurodevelopmental outcomes included the Bayley Scales of Infant Development II administered at 20 months of age, and outcomes across multiple neurodevelopmental domains from 14 tests administered in children and 3 instruments completed by parents when children were 7 years of age. RESULTS The mean cord blood MeHg concentration was 34 (95% CI 11, 75) µg/L. None of the four polymorphisms had a significant association (p < 0.05) with either cord MeHg or neurodevelopmental test results at 20 months. There were no significant associations between either NFE2L2 polymorphism and any developmental test scores. At 7 years, children carrying KEAP1 rs8113472 CA showed significantly worse performance on psychomotor function than children with the CC variant (finger tapping, dominant hand: β - 1.19, SE 0.34; finger tapping, non-dominant hand: β - 0.92, SE 0.31) and worse social communication (SCQ Total: β 0.65, SE 0.27). Children carrying rs8113472 AA, versus children with CC, showed significantly better performance on social communication (SRS Total: β - 8.88, SE 3.60). Children carrying KEAP1 rs9676881 AG, versus children with GG, showed significantly worse performance on psychomotor function (trailmaking A time: β 8.66, SE 3.37) and cognition (KBIT Matrices: β - 0.96, SE 0.36). CONCLUSION No associations between NFE2L2 and KEAP1 polymorphisms and MeHg concentration were identified. However, at 7 years, KEAP1 polymorphisms were associated with differences in neurodevelopmental outcomes in children from a population with high fish intake.
Collapse
Affiliation(s)
- Helena Korres de Paula
- Division of Occupational and Environmental Medicine, Lund University, Lund 22185, Sweden
| | - Tanzy M Love
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA.
| | - Daniela Pineda
- Division of Occupational and Environmental Medicine, Lund University, Lund 22185, Sweden
| | - Gene E Watson
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Sally W Thurston
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Alison J Yeates
- Nutrition Innovation Centre for Food and Health (NICHE), Ulster University, Cromore Road, Coleraine BT52 1SA, Co. Londonderry, UK
| | - Maria S Mulhern
- Nutrition Innovation Centre for Food and Health (NICHE), Ulster University, Cromore Road, Coleraine BT52 1SA, Co. Londonderry, UK
| | - Emeir M McSorley
- Nutrition Innovation Centre for Food and Health (NICHE), Ulster University, Cromore Road, Coleraine BT52 1SA, Co. Londonderry, UK
| | - J J Strain
- Nutrition Innovation Centre for Food and Health (NICHE), Ulster University, Cromore Road, Coleraine BT52 1SA, Co. Londonderry, UK
| | | | - G J Myers
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Matthew D Rand
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Edwin van Wijngaarden
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Karin Broberg
- Division of Occupational and Environmental Medicine, Lund University, Lund 22185, Sweden; Institute of Environmental Medicine, Metals and Health, P.O. Box 210, Stockholm 17177, Sweden
| |
Collapse
|
5
|
Rand MD, Tennessen JM, Mackay TFC, Anholt RRH. Perspectives on the Drosophila melanogaster Model for Advances in Toxicological Science. Curr Protoc 2023; 3:e870. [PMID: 37639638 PMCID: PMC10463236 DOI: 10.1002/cpz1.870] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The use of Drosophila melanogaster for studies of toxicology has grown considerably in the last decade. The Drosophila model has long been appreciated as a versatile and powerful model for developmental biology and genetics because of its ease of handling, short life cycle, low cost of maintenance, molecular genetic accessibility, and availability of a wide range of publicly available strains and data resources. These features, together with recent unique developments in genomics and metabolomics, make the fly model especially relevant and timely for the development of new approach methodologies and movements toward precision toxicology. Here, we offer a perspective on how flies can be leveraged to identify risk factors relevant to environmental exposures and human health. First, we review and discuss fundamental toxicologic principles for experimental design with Drosophila. Next, we describe quantitative and systems genetics approaches to resolve the genetic architecture and candidate pathways controlling susceptibility to toxicants. Finally, we summarize the current state and future promise of the emerging field of Drosophila metabolomics for elaborating toxic mechanisms. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC.
Collapse
Affiliation(s)
- Matthew D. Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | | | - Trudy F. C. Mackay
- Center for Human Genetics and Department of Genetics and Biochemistry, Clemson University, 114 Gregor Mendel Circle, Greenwood, South Carolina 29646, USA
| | - Robert R. H. Anholt
- Center for Human Genetics and Department of Genetics and Biochemistry, Clemson University, 114 Gregor Mendel Circle, Greenwood, South Carolina 29646, USA
| |
Collapse
|
6
|
Everman ER, Macdonald SJ. Gene expression variation underlying tissue-specific responses to copper stress in Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.12.548746. [PMID: 37503205 PMCID: PMC10370140 DOI: 10.1101/2023.07.12.548746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Copper is one of a handful of biologically necessary heavy metals that is also a common environmental pollutant. Under normal conditions, copper ions are required for many key physiological processes. However, in excess, copper quickly results in cell and tissue damage that can range in severity from temporary injury to permanent neurological damage. Because of its biological relevance, and because many conserved copper-responsive genes also respond to other non-essential heavy metal pollutants, copper resistance in Drosophila melanogaster is a useful model system with which to investigate the genetic control of the response to heavy metal stress. Because heavy metal toxicity has the potential to differently impact specific tissues, we genetically characterized the control of the gene expression response to copper stress in a tissue-specific manner in this study. We assessed the copper stress response in head and gut tissue of 96 inbred strains from the Drosophila Synthetic Population Resource (DSPR) using a combination of differential expression analysis and expression quantitative trait locus (eQTL) mapping. Differential expression analysis revealed clear patterns of tissue-specific expression, primarily driven by a more pronounced gene expression response in gut tissue. eQTL mapping of gene expression under control and copper conditions as well as for the change in gene expression following copper exposure (copper response eQTL) revealed hundreds of genes with tissue-specific local cis-eQTL and many distant trans-eQTL. eQTL associated with MtnA, Mdr49, Mdr50, and Sod3 exhibited genotype by environment effects on gene expression under copper stress, illuminating several tissue- and treatment-specific patterns of gene expression control. Together, our data build a nuanced description of the roles and interactions between allelic and expression variation in copper-responsive genes, provide valuable insight into the genomic architecture of susceptibility to metal toxicity, and highlight many candidate genes for future functional characterization.
Collapse
Affiliation(s)
- Elizabeth R Everman
- 1200 Sunnyside Ave, University of Kansas, Molecular Biosciences, Lawrence, KS 66045, USA
- 730 Van Vleet Oval, University of Oklahoma, Biology, Norman, OK 73019, USA
| | - Stuart J Macdonald
- 1200 Sunnyside Ave, University of Kansas, Molecular Biosciences, Lawrence, KS 66045, USA
- 1200 Sunnyside Ave, University of Kansas, Center for Computational Biology, Lawrence, KS 66045, USA
| |
Collapse
|
7
|
Ke T, Tinkov AA, Skalny AV, Santamaria A, Rocha JBT, Bowman AB, Chen W, Aschner M. Epigenetics and Methylmercury-Induced Neurotoxicity, Evidence from Experimental Studies. TOXICS 2023; 11:toxics11010072. [PMID: 36668798 PMCID: PMC9860901 DOI: 10.3390/toxics11010072] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/08/2023] [Accepted: 01/10/2023] [Indexed: 05/14/2023]
Abstract
MeHg is an environmental neurotoxin that can adversely affect the development of the nervous system. The molecular integrity of chromatin in the nucleus is an important target of MeHg. Low levels of MeHg trigger epigenetic mechanisms that may be involved in long-lasting and transgenerational neurotoxicity after exposure. Emerging evidence has shown that these mechanisms include histone modification, siRNA, and DNA methylation. The MeHg-induced inhibition of neurodifferentiation and neurogenesis are mechanistically associated with epigenetic alterations in critical genes, such as neurotrophin brain-derived neurotrophic factor (BDNF). Further, MeHg exposure has been shown to alter the activity and/or expression of the upstream regulators of chromatin structure, including histone deacetylases (HDACs) and DNA methyltransferase (DNMTs), which may trigger permanent alterations in histone modifications and DNA methylation. MeHg-exposure also alters several species of miRNA that are associated with neurodevelopment. Genetic studies in the C. elegans model of MeHg-induced toxicity proposes a potential interplay between exogenous RNAi and antioxidant defense. In this review, we discuss the molecular basis for MeHg exposure-induced alterations in chromatin structure and the roles of histone modifications, siRNA, and DNA methylation in MeHg-induced neurotoxic effects.
Collapse
Affiliation(s)
- Tao Ke
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Correspondence: (T.K.); (M.A.)
| | - Alexey A. Tinkov
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, IM Sechenov First Moscow State Medical University (Sechenov University), 119435 Moscow, Russia
- Laboratory of Ecobiomonitoring and Quality Control, Yaroslavl State University, 150003 Yaroslavl, Russia
- Department of Medical Elementology, RUDN University, 117198 Moscow, Russia
| | - Anatoly V. Skalny
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, IM Sechenov First Moscow State Medical University (Sechenov University), 119435 Moscow, Russia
- Department of Medical Elementology, RUDN University, 117198 Moscow, Russia
| | - Abel Santamaria
- Laboratorio de Aminoácidos Excitadores/Laboratorio de Neurofarmacología Molecular y Nanotecnología, Instituto Nacional de Neurología y Neurocirugía, Mexico City 14269, Mexico
| | - Joao B. T. Rocha
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria 97105-900, RS, Brazil
| | - Aaron B. Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Wen Chen
- Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Correspondence: (T.K.); (M.A.)
| |
Collapse
|
8
|
Fasae KD, Abolaji AO. Interactions and toxicity of non-essential heavy metals (Cd, Pb and Hg): lessons from Drosophila melanogaster. CURRENT OPINION IN INSECT SCIENCE 2022; 51:100900. [PMID: 35272079 DOI: 10.1016/j.cois.2022.100900] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/22/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
Some heavy metals are essential in trace amounts, enhancing enzyme functioning and other intracellular molecules. Others are explicitly toxic at low concentrations, increasing the risk of organ-related toxicity. Non-essential metals have similar mechanisms of toxicity to essential metals. These include the modifiable change in oxidation states, interaction with sulfhydryl moieties of proteins and indirect modification of nucleic acids. Ultimately, oxidative stress is generated, and potentiation of damage ensues. The susceptibility, sensitivity, genetic resources, and cellular response of Drosophila melanogaster to heavy metal exposure and toxicity have made this insect appropriate for toxicological studies. In this review, we focus on the toxicological impacts of non-essential metals (Cd, Pb, and Hg) in Drosophila and discuss its cellular and developmental responses to increasing concentrations of these metals. We also suggest current or proposed therapeutic alternatives, as well as dimensions that may improve the studies of non-essential metal biology.
Collapse
Affiliation(s)
- Kehinde D Fasae
- Drosophila Laboratory, Molecular Drug Metabolism and Toxicology Unit, Department of Biochemistry, Faculty of Basic Medical Sciences, College of Medicine, University of Ibadan, Nigeria; Department of Biomedical and Diagnostic Sciences, University of Tennessee, Knoxville, USA
| | - Amos O Abolaji
- Drosophila Laboratory, Molecular Drug Metabolism and Toxicology Unit, Department of Biochemistry, Faculty of Basic Medical Sciences, College of Medicine, University of Ibadan, Nigeria.
| |
Collapse
|
9
|
Looking at Developmental Neurotoxicity Testing from the Perspective of an Invertebrate Embryo. Int J Mol Sci 2022; 23:ijms23031871. [PMID: 35163796 PMCID: PMC8836978 DOI: 10.3390/ijms23031871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/04/2022] [Accepted: 02/05/2022] [Indexed: 02/01/2023] Open
Abstract
Developmental neurotoxicity (DNT) of chemical compounds disrupts the formation of a normal brain. There is impressive progress in the development of alternative testing methods for DNT potential in chemicals, some of which also incorporate invertebrate animals. This review briefly touches upon studies on the genetically tractable model organisms of Caenorhabditis elegans and Drosophila melanogaster about the action of specific developmental neurotoxicants. The formation of a functional nervous system requires precisely timed axonal pathfinding to the correct cellular targets. To address this complex key event, our lab developed an alternative assay using a serum-free culture of intact locust embryos. The first neural pathways in the leg of embryonic locusts are established by a pair of afferent pioneer neurons which use guidance cues from membrane-bound and diffusible semaphorin proteins. In a systematic approach according to recommendations for alternative testing, the embryo assay quantifies defects in pioneer navigation after exposure to a panel of recognized test compounds for DNT. The outcome indicates a high predictability for test-compound classification. Since the pyramidal neurons of the mammalian cortex also use a semaphorin gradient for neurite guidance, the assay is based on evolutionary conserved cellular mechanisms, supporting its relevance for cortical development.
Collapse
|
10
|
Wildner G, Loreto JS, de Almeida P, Claro MT, Ferreira SA, Barbosa NV. Short exposure to ethyl and methylmercury prompts similar toxic responses in Drosophila melanogaster. Comp Biochem Physiol C Toxicol Pharmacol 2022; 252:109216. [PMID: 34710619 DOI: 10.1016/j.cbpc.2021.109216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/07/2021] [Accepted: 10/14/2021] [Indexed: 12/30/2022]
Abstract
Methylmercury (MeHg) and ethylmercury (EtHg) are important mercury organic forms in terms of human poisoning. Since the comparative effects of compounds are mainly in vitro, this study was designed to investigate the toxicities induced by MeHg and EtHg in an in vivo study using adult Drosophila melanogaster (D. melanogaster). Firstly, we performed a survival curve, where the flies were fed on a medium containing MeHg and EtHg at concentrations ranging from 2.5 to 200 μM, until the end of their lifespan. After that, the concentrations 25 and 200 μM of MeHg and EtHg were chosen to be tested in a short exposure for 5 days. The analysis of survival by Kaplan-Meier plot revealed that all concentrations of MeHg and EtHg reduced significantly the lifespan of the flies. Short exposure to both concentrations of MeHg and EtHg impaired the ability of flies in the climbing assay and induced lipid peroxidation. Only the flies exposed to the highest concentration had viability loss, thiol depletion, and increased reactive species (RS) and Hg levels in the whole body. Our findings indicate that MeHg and EtHg exhibit similar toxic effects in vivo, and that oxidative stress is a phenomenon behind the toxicity of both mercurials. The data obtained also reinforce the use of D. melanogaster as a useful organism for basic toxicological research.
Collapse
Affiliation(s)
- Guilherme Wildner
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Julia Sepel Loreto
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Pamela de Almeida
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Mariana Torri Claro
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Sabrina Antunes Ferreira
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil
| | - Nilda Vargas Barbosa
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Avenida Roraima, 1000, 97105-900 Santa Maria, RS, Brazil.
| |
Collapse
|
11
|
Gunderson JT, Peppriell AE, Krout IN, Vorojeikina D, Rand MD. Neuroligin-1 Is a Mediator of Methylmercury Neuromuscular Toxicity. Toxicol Sci 2021; 184:236-251. [PMID: 34546366 DOI: 10.1093/toxsci/kfab114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Methylmercury (MeHg) is a developmental toxicant capable of eliciting neurocognitive and neuromuscular deficits in children with in utero exposure. Previous research in Drosophila melanogaster uncovered that developmental MeHg exposure simultaneously targets the developing musculature and innervating motor neuron in the embryo, along with identifying Drosophila neuroligin 1 (nlg1) as a gene associated with developmental MeHg sensitivity. Nlg1 and its transsynaptic partner neurexin 1 (Nrx1) are critical for axonal arborization and NMJ maturation. We investigated the effects of MeHg exposure on indirect flight muscle (IFM) morphogenesis, innervation, and function via flight assays and monitored the expression of NMJ-associated genes to characterize the role of Nlg1 mediating the neuromuscular toxicity of MeHg. Developmental MeHg exposure reduced the innervation of the IFMs, which corresponded with reduced flight ability. In addition, nlg1 expression was selectively reduced during early metamorphosis, whereas a subsequent increase was observed in other NMJ-associated genes, including nrx1, in late metamorphosis. Developmental MeHg exposure also resulted in persistent reduced expression of most nlg and nrx genes during the first 11 days of adulthood. Transgenic modulation of nlg1 and nrx1 revealed that developing muscle is particularly sensitive to nlg1 levels, especially during the 20-36-h window of metamorphosis with reduced nlg1 expression resulting in adult flight deficits. Muscle-specific overexpression of nlg1 partially rescued MeHg-induced deficits in eclosion and flight. We identified Nlg1 as a muscle-specific, NMJ structural component that can mediate MeHg neuromuscular toxicity resulting from early life exposure.
Collapse
Affiliation(s)
- Jakob T Gunderson
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Ashley E Peppriell
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Ian N Krout
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Daria Vorojeikina
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Matthew D Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| |
Collapse
|
12
|
Peppriell AE, Gunderson JT, Krout IN, Vorojeikina D, Rand MD. Latent effects of early-life methylmercury exposure on motor function in Drosophila. Neurotoxicol Teratol 2021; 88:107037. [PMID: 34656729 DOI: 10.1016/j.ntt.2021.107037] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 09/25/2021] [Accepted: 10/10/2021] [Indexed: 12/27/2022]
Abstract
The developmental toxicant, methylmercury (MeHg), can elicit motor deficits that last well into adulthood. Recent studies using Drosophila showed that the developing musculature is sensitive to high doses of MeHg, where a larval feeding paradigm resulted in compromised myotendinous junction (MTJ) formation during development, by a mechanism involving the NG2 homologue, kon-tiki (kon). Low-dose exposures to MeHg that do not produce muscle pathology during development, nevertheless result in impaired flight behavior later in adult life. The present study evaluated the potential for relatively low-dose exposure to produce latent adult muscle pathology and motor impairments, as assayed by climbing and flight, as well as to evaluate molecular mechanisms that may contribute to motor deficits. Wildtype larvae were fed 0, 2, 2.5, or 5 μM MeHg laden food until eclosion. The effect of 5 μM MeHg on MTJ-related gene expression during pupal development was assessed via quantitative RT-qPCR analysis. Upon eclosion, adults were transferred to standard food bottles for 4, 11, or 30 days prior to motor testing. Survivorship (%) was determined from a subset of 200 flies per treatment. Average climbing speed (cm/s) was quantified 4-days post-eclosion (PE). Flight ability was assayed 11- or 30-days PE by measuring landing height (cm) of flies dropped into an adhesive-lined vertical column. In parallel, total body mercury was measured to estimate the influence of residual MeHg at the time of motor testing. Muscle morphology was assessed using immuno-fluorescence microscopy. Exposure to 5uM MeHg significantly reduced climbing speed, and flight ability 4 and 11 - days PE, respectively. While age-related flight deficits were seen in each sex, flight deficits due to MeHg persisted to 30-day PE timepoints exclusively in males. Expression of kon was upregulated across the window of pupal development essential to establishing adult MTJ. However, experimentally restricting the induction of comparable levels of kon to muscle during the same periods did not recapitulate the flight deficits, indicating that muscle-specific induction of kon alone is not sufficient to contribute to latent flight impairments. Adult flight muscle morphology of 11-day PE flies treated with 5 μM MeHg was indistinct from controls, implying muscle structure is not grossly perturbed to impair flight. Collectively, the current data suggest that developmental exposure to 5 μM MeHg reduces flight ability in each sex at 11 day-PE and that latent deficits at 30-day PE are male-specific. It remains to be determined whether the developing MTJ of Drosophila is a sensitive target of MeHg, and whether or not kon acts in conjunction with additional MTJ factors to constitute a MeHg target.
Collapse
Affiliation(s)
- Ashley E Peppriell
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA; ICF International, Durham, NC, USA.
| | - Jakob T Gunderson
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Ian N Krout
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Daria Vorojeikina
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Matthew D Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| |
Collapse
|
13
|
Martins AC, Ke T, Bowman AB, Aschner M. New insights on mechanisms underlying methylmercury-induced and manganese-induced neurotoxicity. CURRENT OPINION IN TOXICOLOGY 2021; 25:30-35. [PMID: 33898886 PMCID: PMC8061890 DOI: 10.1016/j.cotox.2021.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Toxic and essential elements are widely distributed in the Earth's crust and individuals may be exposed to several of them. Indeed, exposure to toxic elements such as mercury (Hg) can be a potential health risk factor of health, mainly by ingestion of fish containing methylmercury (MeHg). On the other hand, essential elements such as manganese (Mn) play an important role in physiological process in human body. However, Mn overexposure may cause toxic effects. In this respect, the neurotoxic effects of MeHg and Mn on the developing brain are well recognized. Therefore, in this critical review, we address the effects of MeHg and Mn on cell signaling pathways which may contribute to molecular mechanisms involved in MeHg- and Mn-induced neurotoxicity.
Collapse
Affiliation(s)
- Airton C Martins
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Tao Ke
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| |
Collapse
|