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Hernandez-Toledano D, Vega L. The cytoskeleton as a non-cholinergic target of organophosphate compounds. Chem Biol Interact 2021; 346:109578. [PMID: 34265256 DOI: 10.1016/j.cbi.2021.109578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/19/2021] [Accepted: 07/12/2021] [Indexed: 12/29/2022]
Abstract
Current organophosphate (OP) toxicity research now considers potential non-cholinergic mechanisms for these compounds, since the inhibition of acetylcholinesterase (AChE) cannot completely explain all the adverse biological effects of OP. Thanks to the development of new strategies for OP detection, some potential molecular targets have been identified. Among these molecules are several cytoskeletal proteins, including actin, tubulin, intermediate filament proteins, and associated proteins, such as motor proteins, microtubule-associated proteins (MAPs), and cofilin. in vitro, ex vivo, and some in vivo reports have identified alterations in the cytoskeleton following OP exposure, including cell morphology defects, cells detachments, intracellular transport disruption, aberrant mitotic spindle formation, modification of cell motility, and reduced phagocytic capability, which implicate the cytoskeleton in OP toxicity. Here, we reviewed the evidence indicating the cytoskeletal targets of OP compounds, including their strategies, the potential effects of their alterations, and their possible participation in neurotoxicity, embryonic development, cell division, and immunotoxicity related to OP compounds exposure.
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Affiliation(s)
- David Hernandez-Toledano
- Department of Toxicology, Center for Research and Advanced Studies of the National Polytechnic Institute. Av. IPN 2508, San Pedro Zacatenco, C.P. 07360, Mexico City, Mexico
| | - Libia Vega
- Department of Toxicology, Center for Research and Advanced Studies of the National Polytechnic Institute. Av. IPN 2508, San Pedro Zacatenco, C.P. 07360, Mexico City, Mexico.
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2
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Felemban SG, Vyas FS, Durose L, Hargreaves AJ, Dickenson JM. Phenyl Saligenin Phosphate Disrupts Cell Morphology and the Actin Cytoskeleton in Differentiating H9c2 Cardiomyoblasts and Human-Induced Pluripotent Stem-Cell-Derived Cardiomyocyte Progenitor Cells. Chem Res Toxicol 2020; 33:2310-2323. [PMID: 32786544 DOI: 10.1021/acs.chemrestox.0c00100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have previously shown that phenyl saligenin phosphate (PSP), an organophosphorus compound which is classed as a weak inhibitor of acetylcholinesterase, triggered cytotoxicity in mitotic and differentiated H9c2 cardiomyoblasts. The aim of this study was to assess whether sublethal concentrations of PSP could disrupt the morphology of differentiating rat H9c2 cardiomyoblasts and human-induced pluripotent stem-cell-derived cardiomyocyte progenitor cells (hiPSC-CMs) and to assess the underlying cytoskeletal changes. PSP-induced changes in protein expression were monitored via Western blotting, immunocytochemistry, and proteomic analysis. PSP-mediated cytotoxicity was determined by measuring MTT reduction, LDH release, and caspase-3 activity. Sublethal exposure to PSP (3 μM) induced morphological changes in differentiating H9c2 cells (7, 9, and 13 days), reflected by reduced numbers of spindle-shaped cells. Moreover, this treatment (7 days) attenuated the expression of the cytoskeletal proteins cardiac troponin I, tropomyosin-1, and α-actin. Further proteomic analysis identified nine proteins (e.g., heat shock protein 90-β and calumenin) which were down-regulated by PSP exposure in H9c2 cells. To assess the cytotoxic effects of organophosphorus compounds in a human cell model, we determined their effects on human-induced pluripotent stem-cell-derived cardiomyocyte progenitor cells. Chlorpyrifos and diazinon-induced cytotoxicity (48 h) was evident only at concentrations >100 μM. By contrast, PSP exhibited cytotoxicity in hiPSC-CMs at a concentration of 25 μM following 48 h exposure. Finally, sublethal exposure to PSP (3 μM; 7 days) induced morphological changes and decreased the expression of cardiac troponin I, tropomyosin-1, and α-actin in hiPSC-CMs. In summary, our data suggest cardiomyocyte morphology is disrupted in both cell models by sublethal concentrations of PSP via modulation of cytoskeletal protein expression.
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Affiliation(s)
- Shatha G Felemban
- School of Science and Technology Nottingham Trent University Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - Falguni S Vyas
- School of Science and Technology Nottingham Trent University Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - Lyndsey Durose
- School of Science and Technology Nottingham Trent University Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - Alan J Hargreaves
- School of Science and Technology Nottingham Trent University Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - John M Dickenson
- School of Science and Technology Nottingham Trent University Clifton Lane, Nottingham NG11 8NS, United Kingdom
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3
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Almami IS, Aldubayan MA, Felemban SG, Alyamani N, Howden R, Robinson AJ, Pearson TDZ, Boocock D, Algarni AS, Garner AC, Griffin M, Bonner PLR, Hargreaves AJ. Neurite outgrowth inhibitory levels of organophosphates induce tissue transglutaminase activity in differentiating N2a cells: evidence for covalent adduct formation. Arch Toxicol 2020; 94:3861-3875. [PMID: 32749514 PMCID: PMC7603472 DOI: 10.1007/s00204-020-02852-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 07/14/2020] [Indexed: 02/06/2023]
Abstract
Organophosphate compounds (OPs) induce both acute and delayed neurotoxic effects, the latter of which is believed to involve their interaction with proteins other than acetylcholinesterase. However, few OP-binding proteins have been identified that may have a direct role in OP-induced delayed neurotoxicity. Given their ability to disrupt Ca2+ homeostasis, a key aim of the current work was to investigate the effects of sub-lethal neurite outgrowth inhibitory levels of OPs on the Ca2+-dependent enzyme tissue transglutaminase (TG2). At 1-10 µM, the OPs phenyl saligenin phosphate (PSP) and chlorpyrifos oxon (CPO) had no effect cell viability but induced concentration-dependent decreases in neurite outgrowth in differentiating N2a neuroblastoma cells. The activity of TG2 increased in cell lysates of differentiating cells exposed for 24 h to PSP and chlorpyrifos oxon CPO (10 µM), as determined by biotin-cadaverine incorporation assays. Exposure to both OPs (3 and/or 10 µM) also enhanced in situ incorporation of the membrane permeable substrate biotin-X-cadaverine, as indicated by Western blot analysis of treated cell lysates probed with ExtrAvidin peroxidase and fluorescence microscopy of cell monolayers incubated with FITC-streptavidin. Both OPs (10 µM) stimulated the activity of human and mouse recombinant TG2 and covalent labelling of TG2 with dansylamine-labelled PSP was demonstrated by fluorescence imaging following SDS-PAGE. A number of TG2 substrates were tentatively identified by mass spectrometry, including cytoskeletal proteins, chaperones and proteins involved protein synthesis and gene regulation. We propose that the elevated TG2 activity observed is due to the formation of a novel covalent adduct between TG2 and OPs.
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Affiliation(s)
- Ibtesam S Almami
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK.,Department of Biology, College of Science, Qassim University, Al-Qassim, Saudi Arabia
| | - Maha A Aldubayan
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK.,Department of Pharmacology and Toxicology, College of Pharmacy, Qassim University, Al-Qassim, Saudi Arabia
| | - Shatha G Felemban
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK.,Department of Medical Laboratory Science, Fakeeh College for Medical Science, Jeddah, Saudi Arabia
| | - Najiah Alyamani
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK.,Department of Biology, Faculty of Science, University of Jeddah, Jeddah, Kingdom of Saudi Arabia
| | - Richard Howden
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK
| | - Alexander J Robinson
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK.,Department of Life Sciences, School of Health Sciences, Birmingham City University, City South Campus, Edgbaston, B15 3TN, UK
| | - Tom D Z Pearson
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK
| | - David Boocock
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK
| | - Alanood S Algarni
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK.,Department of Pharmacology and Toxicology, Faculty of Pharmacy, Umm Al-Qura University, Mekkah, Saudi Arabia
| | - A Christopher Garner
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK
| | - Martin Griffin
- Department of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Philip L R Bonner
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK
| | - Alan J Hargreaves
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK.
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4
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Ling H, He J, Tan H, Yi L, Liu F, Ji X, Wu Y, Hu H, Zeng X, Ai X, Jiang H, Su Q. Identification of potential targets for differentiation in human leukemia cells induced by diallyl disulfide. Int J Oncol 2017; 50:697-707. [PMID: 28101575 DOI: 10.3892/ijo.2017.3839] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 12/27/2016] [Indexed: 11/06/2022] Open
Abstract
Diallyl disulfide (DADS) is a primary component of garlic, which has chemopreventive potential. We previously found that moderate doses (15-120 µM) of DADS induced apoptosis and G2/M phase cell cycle arrest. In this study, we observed the effect of low doses (8 µM) of DADS on human leukemia HL-60 cells. We found that DADS could inhibit proliferation, migration and invasion in HL-60 cells, and arrested cells at G0/G1 stage. Then, cell differentiation was displayed by morphologic observation, NBT reduction activity and CD11b evaluation of cytometric flow. It showed that DADS induced differentiation, reduced the ability of NBT and increased CD11b expression. Likewise, DADS inhibited xenograft tumor growth and induced differentiation in vivo. In order to make sure how DADS induced differentiation, we compared the protein expression profile of DADS-treated cells with that of untreated control. Using high resolution mass spectrometry, we identified 18 differentially expressed proteins after treatment with DADS, including four upregulated and 14 downregulated proteins. RT-PCR and western blot assay showed that DJ-1, cofilin 1, RhoGDP dissociation inhibitor 2 (RhoGDI2), Calreticulin (CTR) and PCNA were decreased by DADS. These data suggest that the effects of DADS on leukemia may be due to multiple targets for intervention.
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Affiliation(s)
- Hui Ling
- Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Jie He
- Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Hui Tan
- Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Lan Yi
- Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Fang Liu
- Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Xiaoxia Ji
- Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Youhua Wu
- The First Affiliated Hospital, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Haobin Hu
- Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Xi Zeng
- Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Xiaohong Ai
- The First Affiliated Hospital, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Hao Jiang
- The First Affiliated Hospital, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Qi Su
- Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, P.R. China
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Sindi RA, Harris W, Arnott G, Flaskos J, Lloyd Mills C, Hargreaves AJ. Chlorpyrifos- and chlorpyrifos oxon-induced neurite retraction in pre-differentiated N2a cells is associated with transient hyperphosphorylation of neurofilament heavy chain and ERK 1/2. Toxicol Appl Pharmacol 2016; 308:20-31. [DOI: 10.1016/j.taap.2016.08.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Revised: 07/27/2016] [Accepted: 08/09/2016] [Indexed: 11/26/2022]
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6
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Rabilloud T, Lescuyer P. Proteomics in mechanistic toxicology: History, concepts, achievements, caveats, and potential. Proteomics 2014; 15:1051-74. [DOI: 10.1002/pmic.201400288] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 07/25/2014] [Accepted: 08/25/2014] [Indexed: 12/19/2022]
Affiliation(s)
- Thierry Rabilloud
- Laboratory of Chemistry and Biology of Metals; CNRS UMR; 5249 Grenoble France
- Laboratory of Chemistry and Biology of Metals; Université Grenoble Alpes; Grenoble France
- Laboratory of Chemistry and Biology of Metals; CEA Grenoble; iRTSV/CBM; Grenoble France
| | - Pierre Lescuyer
- Department of Human Protein Sciences; Clinical Proteomics and Chemistry Group; Geneva University; Geneva Switzerland
- Toxicology and Therapeutic Drug Monitoring Laboratory; Department of Genetic and Laboratory Medicine; Geneva University Hospitals; Geneva Switzerland
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Lari P, Rashedinia M, Abnous K, Hosseinzadeh H. Alteration of protein profile in rat liver of animals exposed to subacute diazinon: A proteomic approach. Electrophoresis 2014; 35:1419-27. [DOI: 10.1002/elps.201300475] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Revised: 01/22/2014] [Accepted: 01/24/2014] [Indexed: 02/06/2023]
Affiliation(s)
- Parisa Lari
- Department of Pharmacodynamy and Toxicology; School of Pharmacy; Mashhad University of Medical Sciences; Mashhad Iran
| | - Marzieh Rashedinia
- Department of Pharmacodynamy and Toxicology; School of Pharmacy; Mashhad University of Medical Sciences; Mashhad Iran
| | - Khalil Abnous
- Department of Pharmacodynamy and Toxicology; School of Pharmacy; Mashhad University of Medical Sciences; Mashhad Iran
| | - Hossein Hosseinzadeh
- Department of Pharmacodynamy and Toxicology; School of Pharmacy; Mashhad University of Medical Sciences; Mashhad Iran
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8
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Tao Y, Fang L, Yang Y, Jiang H, Yang H, Zhang H, Zhou H. Quantitative proteomic analysis reveals the neuroprotective effects of huperzine A for amyloid beta treated neuroblastoma N2a cells. Proteomics 2013; 13:1314-24. [DOI: 10.1002/pmic.201200437] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 11/25/2012] [Accepted: 11/26/2012] [Indexed: 02/04/2023]
Affiliation(s)
| | | | | | - Hualiang Jiang
- Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai; China
| | - Huaiyu Yang
- Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai; China
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9
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Neurodegenerations Induced by Organophosphorous Compounds. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 724:189-204. [DOI: 10.1007/978-1-4614-0653-2_15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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10
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Effects of sub-lethal neurite outgrowth inhibitory concentrations of chlorpyrifos oxon on cytoskeletal proteins and acetylcholinesterase in differentiating N2a cells. Toxicol Appl Pharmacol 2011; 256:330-6. [DOI: 10.1016/j.taap.2011.06.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 06/01/2011] [Accepted: 06/03/2011] [Indexed: 11/18/2022]
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11
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Huang QY, Huang HQ. Differential expression profile of membrane proteins in zebrafish (Danio rerio
) brain exposed to methyl parathion. Proteomics 2011; 11:3743-56. [DOI: 10.1002/pmic.201100084] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 06/29/2011] [Accepted: 07/01/2011] [Indexed: 12/12/2022]
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12
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NOMURA DANIELK, CASIDA JOHNE. Activity-based protein profiling of organophosphorus and thiocarbamate pesticides reveals multiple serine hydrolase targets in mouse brain. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:2808-15. [PMID: 21341672 PMCID: PMC3071868 DOI: 10.1021/jf101747r] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Organophosphorus (OP) and thiocarbamate (TC) agrochemicals are used worldwide as insecticides, herbicides, and fungicides, but their safety assessment in terms of potential off-targets remains incomplete. In this study, a chemoproteomic platform, termed activity-based protein profiling, was used to broadly define serine hydrolase targets in mouse brain of a panel of 29 OP and TC pesticides. Among the secondary targets identified, enzymes involved in the degradation of endocannabinoid signaling lipids, monoacylglycerol lipase, and fatty acid amide hydrolase were inhibited by several OP and TC pesticides. Blockade of these two enzymes led to elevations in brain endocannabinoid levels and dysregulated brain arachidonate metabolism. Other secondary targets include enzymes thought to also play important roles in the nervous system and unannotated proteins. This study reveals a multitude of secondary targets for OP and TC pesticides and underscores the utility of chemoproteomic platforms in gaining insights into biochemical pathways that are perturbed by these toxicants.
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Affiliation(s)
- DANIEL K. NOMURA
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037
- Authors to whom correspondence should be addressed. and
| | - JOHN E. CASIDA
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, California 94720
- Authors to whom correspondence should be addressed. and
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Huang QY, Huang L, Huang HQ. Proteomic analysis of methyl parathion-responsive proteins in zebrafish (Danio rerio) brain. Comp Biochem Physiol C Toxicol Pharmacol 2011; 153:67-74. [PMID: 20826231 DOI: 10.1016/j.cbpc.2010.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 08/30/2010] [Accepted: 08/30/2010] [Indexed: 12/22/2022]
Abstract
Methyl parathion (MP), an organophosphorus pesticide used worldwide, has been associated with a wide spectrum of toxic effects on organisms in the environment. This study set out to analyze the alteration of protein profiles in MP-exposed zebrafish (Danio rerio) brain and find the proteins responsive to MP toxicity. Zebrafish were subjected to 1, 3 and 5mg/L MP and the proteomic changes in their brains were revealed using two-dimensional gel electrophoresis. Six protein spots were observed to be significantly changed by MP exposure. Among these, 4 spots were down-regulated, while 2 spots were up-regulated. These altered spots were excised from the gels and identified by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry and database searching. The results indicate that these proteins were involved in binding, catalysis, regulation of energy metabolism and cell structure. These data may provide novel biomarkers for the evaluation of MP contamination and useful insights for understanding the mechanisms of MP toxicity.
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Affiliation(s)
- Qing-Yu Huang
- Department of Biochemistry and Biotechnology, School of Life Sciences, Xiamen University, Xiamen 361005, China
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Cabaj M, Toman R, Adamkovičová M, Massányi P, Šiška B, Lukáč N, Golian J. STRUCTURAL CHANGES IN THE RAT TESTIS CAUSED BY DIAZINON AND SELENIUM. POTRAVINARSTVO 2010. [DOI: 10.5219/44] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Jiang W, Duysen EG, Hansen H, Shlyakhtenko L, Schopfer LM, Lockridge O. Mice treated with chlorpyrifos or chlorpyrifos oxon have organophosphorylated tubulin in the brain and disrupted microtubule structures, suggesting a role for tubulin in neurotoxicity associated with exposure to organophosphorus agents. Toxicol Sci 2010; 115:183-93. [PMID: 20142434 DOI: 10.1093/toxsci/kfq032] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Exposure to organophosphorus (OP) agents can lead to learning and memory deficits. Disruption of axonal transport has been proposed as a possible explanation. Microtubules are an essential component of axonal transport. In vitro studies have demonstrated that OP agents react with tubulin and disrupt the structure of microtubules. Our goal was to determine whether in vivo exposure affects microtubule structure. One group of mice was treated daily for 14 days with a dose of chlorpyrifos that did not significantly inhibit acetylcholinesterase. Beta-tubulin from the brains of these mice was diethoxyphosphorylated on tyrosine 281 in peptide GSQQY(281)RALTVPELTQQMFDSK. A second group of mice was treated with a single sublethal dose of chlorpyrifos oxon (CPO). Microtubules and cosedimenting proteins from the brains of these mice were visualized by atomic force microscopy nanoimaging and by Coomassie blue staining of polyacrylamide gel electrophoresis bands. Proteins in gel slices were identified by mass spectrometry. Nanoimaging showed that microtubules from control mice were decorated with many proteins, whereas microtubules from CPO-treated mice had fewer associated proteins, a result confirmed by mass spectrometry of proteins extracted from gel slices. The dimensions of microtubules from CPO-treated mice (height 8.7 +/- 3.1 nm and width 36.5 +/- 15.5 nm) were about 60% of those from control mice (height 13.6 +/- 3.6 nm and width 64.8 +/- 15.9 nm). A third group of mice was treated with six sublethal doses of CPO over 50.15 h. Mass spectrometry identified diethoxyphosphorylated serine 338 in peptide NS(338)NFVEWIPNNVK of beta-tubulin. In conclusion, microtubules from mice exposed to chlorpyrifos or to CPO have covalently modified amino acids and abnormal structure, suggesting disruption of microtubule function. Covalent binding of CPO to tubulin and to tubulin-associated proteins is a potential mechanism of neurotoxicity.
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Affiliation(s)
- Wei Jiang
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950, USA
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