1
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Chu S, Li XH, Letcher RJ. Covalent adduct formation of histone with organophosphorus pesticides in vitro. Chem Biol Interact 2024; 398:111095. [PMID: 38844256 DOI: 10.1016/j.cbi.2024.111095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 05/30/2024] [Accepted: 06/03/2024] [Indexed: 06/11/2024]
Abstract
It is established that organophosphorus pesticide (OPP) toxicity results from modification of amino acids in active sites of target proteins. OPPs can also modify unrelated target proteins such as histones and such covalent histone modifications can alter DNA-binding properties and lead to aberrant gene expression. In the present study, we report on non-enzymatic covalent modifications of calf thymus histones adducted to selected OPPs and organophosphate flame retardants (OPFRs) in vitro using a bottom-up proteomics method approach. Histones were not found to form detectable adducts with the two tested OPFRs but were avidly modified by a few of the seven OPPs that were tested in vitro. Dimethyl phosphate (or diethyl phosphate) adducts were identified on Tyr, Lys and Ser residues. Most of the dialkyl phosphate adducts were identified on Tyr residues. Methyl and ethyl modified histones were also detected. Eleven amino residues in histones showed non-enzymatic covalent methylation by exposure of dichlorvos and malathion. Our bottom-up proteomics approach showing histone-OPP adduct formation warrants future studies on the underlying mechanism of chronic illness from exposure to OPPs.
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Affiliation(s)
- Shaogang Chu
- Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1A 0H3, Canada.
| | - Xing-Hong Li
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Haidian District, No. 18, Shuangqing Road, Beijing, 100085, PR China.
| | - Robert J Letcher
- Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1A 0H3, Canada.
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2
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Hernández-Toledano DS, Vega L. Methylated dialkylphosphate metabolites of the organophosphate pesticide malathion modify actin cytoskeleton arrangement and cell migration via activation of Rho GTPases Rac1 and Cdc42. Chem Biol Interact 2023; 382:110593. [PMID: 37270087 DOI: 10.1016/j.cbi.2023.110593] [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: 04/18/2023] [Revised: 05/08/2023] [Accepted: 06/01/2023] [Indexed: 06/05/2023]
Abstract
The non-cholinergic molecular targets of organophosphate (OP) compounds have recently been investigated to explain their role in the generation of non-neurological diseases, such as immunotoxicity and cancer. Here, we evaluated the effects of malathion and its dialkylphosphate (DAP) metabolites on the cytoskeleton components and organization of RAW264.7 murine macrophages as non-cholinergic targets of OP and DAPs toxicity. All OP compounds affected actin and tubulin polymerization. Malathion, dimethyldithiophosphate (DMDTP) dimethylthiophosphate (DMTP), and dimethylphosphate (DMP) induced elongated morphologies and the formation of pseudopods rich in microtubule structures, and increased filopodia formation and general actin disorganization in RAW264.7 cells and slightly reduced stress fibers in the human fibroblasts GM03440, without significantly disrupting the tubulin or vimentin cytoskeleton. Exposure to DMTP and DMP increased cell migration in the wound healing assay but did not affect phagocytosis, indicating a very specific modification in the organization of the cytoskeleton. The induction of actin cytoskeleton rearrangement and cell migration suggested the activation of cytoskeletal regulators such as small GTPases. We found that DMP slightly reduced Ras homolog family member A activity but increased the activities of Ras-related C3 botulinum toxin substrate 1 (Rac1) and cell division control protein 42 (Cdc42) from 5 min to 2 h of exposure. Chemical inhibition of Rac1 with NSC23766 reduced cell polarization and treatment with DMP enhanced cell migration, but Cdc42 inhibition by ML-141 completely inhibited the effects of DMP. These results suggest that methylated OP compounds, especially DMP, can modify macrophage cytoskeleton function and configuration via activation of Cdc42, which may represent a potential non-cholinergic molecular target for OP compounds.
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Affiliation(s)
- David Sebastián Hernández-Toledano
- Department of Toxicology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico. Av. Instituto Politécnico Nacional 2508, San Pedro Zacatenco, C.P. 07360, Gustavo A. Madero, Ciudad de México, Mexico
| | - Libia Vega
- Department of Toxicology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico. Av. Instituto Politécnico Nacional 2508, San Pedro Zacatenco, C.P. 07360, Gustavo A. Madero, Ciudad de México, Mexico.
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3
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Lockridge O, Schopfer LM. Review: Organophosphorus toxicants, in addition to inhibiting acetylcholinesterase activity, make covalent adducts on multiple proteins and promote protein crosslinking into high molecular weight aggregates. Chem Biol Interact 2023; 376:110460. [PMID: 36963650 PMCID: PMC10100150 DOI: 10.1016/j.cbi.2023.110460] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 03/08/2023] [Accepted: 03/15/2023] [Indexed: 03/26/2023]
Abstract
The acute effects of exposure to organophosphorus toxicants are explained by inhibition of acetylcholinesterase activity. However, the mechanisms that explain long term illness associated with organophosphorus exposure are still under investigation. We find that organophosphorus nerve agents and organophosphorus pesticides make covalent adducts not only on the serine from acetylcholinesterase, but also on tyrosine, lysine, glutamate, serine and threonine from a variety of proteins. Almost any protein can be modified by a high dose of organophosphorus toxicant. A low dose of 10 μM chlorpyrifos oxon added to the serum-free culture medium of human neuroblastoma SH-SY5Y cells resulted in tyrosine adducts on 48 proteins immunopurified from the cell lysate. We identified the adducted proteins by mass spectrometry after immunopurifying modified proteins with a rabbit anti-diethoxyphospho-tyrosine monoclonal antibody which biased this study for tyrosine adducts. In cultured cells, the primary organophosphate targets are abundant proteins. Organophosphate-modified proteins may disrupt physiological processes. In separate experiments we identified organophosphate adducts on lysine. Organophosphylation activates the lysine for protein crosslinking. The activated lysine reacts with glutamic acid or aspartic acid protein side chains to form an isopeptide bond between proteins, resulting in high molecular weight crosslinked proteins. Crosslinked proteins form insoluble aggregates that may lead to neurogenerative disease.
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Affiliation(s)
- Oksana Lockridge
- Eppley Institute, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
| | - Lawrence M Schopfer
- Eppley Institute, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
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4
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Gong S, Hu X, Chen S, Sun B, Wu JL, Li N. Dual roles of drug or its metabolite-protein conjugate: Cutting-edge strategy of drug discovery using shotgun proteomics. Med Res Rev 2022; 42:1704-1734. [PMID: 35638460 DOI: 10.1002/med.21889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 03/24/2022] [Accepted: 05/04/2022] [Indexed: 11/11/2022]
Abstract
Many drugs can bind directly to proteins or be bioactivated by metabolizing enzymes to form reactive metabolites (RMs) that rapidly bind to proteins to form drug-protein conjugates or metabolite-protein conjugates (DMPCs). The close relationship between DMPCs and idiosyncratic adverse drug reactions (IADRs) has been recognized; drug discovery teams tend to avoid covalent interactions in drug discovery projects. Covalent interactions in DMPCs can provide high potency and long action duration and conquer the intractable targets, inspiring drug design, and development. This forms the dual role feature of DMPCs. Understanding the functional implications of DMPCs in IADR control and therapeutic applications requires precise identification of these conjugates from complex biological samples. While classical biochemical methods have contributed significantly to DMPC detection in the past decades, the low abundance and low coverage of DMPCs have become a bottleneck in this field. An emerging transformation toward shotgun proteomics is on the rise. The evolving shotgun proteomics techniques offer improved reproducibility, throughput, specificity, operability, and standardization. Here, we review recent progress in the systematic discovery of DMPCs using shotgun proteomics. Furthermore, the applications of shotgun proteomics supporting drug development, toxicity mechanism investigation, and drug repurposing processes are also reviewed and prospected.
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Affiliation(s)
- Shilin Gong
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macau
| | - Xiaolan Hu
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macau
| | - Shengshuang Chen
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macau
| | - Baoqing Sun
- State Key Laboratory of Respiratory Disease, National Respiratory Medical Center, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Jian-Lin Wu
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macau
| | - Na Li
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macau
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5
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Lockridge O, Schopfer LM. Naturally Occurring Epsilon Gamma Glutamyl Lysine Isopeptide Crosslinks in Human Neuroblastoma SH-SY5Y Cells. ACS OMEGA 2022; 7:21978-21986. [PMID: 35785306 PMCID: PMC9245130 DOI: 10.1021/acsomega.2c02502] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 06/07/2022] [Indexed: 05/05/2023]
Abstract
Zero-length isopeptide crosslinks between the side chains of glutamine and lysine are the product of transglutaminase activity. It is generally accepted that transglutaminase activity is dormant under physiological conditions because the calcium concentration inside cells is too low to activate transglutaminase to an open conformation with access to the catalytic triad. Traditional assays for transglutaminase activity measure incorporation of biotin pentylamine or of radiolabeled putrescine in the presence of added calcium. In this report, we identified naturally occurring isopeptide crosslinked proteins using the following steps: immunopurification of tryptic peptides by binding to anti-isopeptide antibody 81D1C2, separation of immunopurified peptides by liquid chromatography-tandem mass spectrometry, Protein Prospector database searches of mass spectrometry data for isopeptide crosslinked peptides, and manual evaluation of candidate crosslinked peptide pairs. The most labor intense step was manual evaluation. We developed criteria for accepting and rejecting candidate crosslinked peptides and showed examples of MS/MS spectra that confirm or invalidate a possible crosslink. The SH-SY5Y cells that we examined for crosslinked proteins had not been exposed to calcium and had been lysed in the presence of ethylenediaminetetraacetic acid. This precaution allows us to claim that the crosslinks we found inside the cells occurred naturally under physiological conditions. The quantity of crosslinks was very low, and the crosslinked proteins were mostly low abundance proteins. In conclusion, intracellular transglutaminase crosslinking/transamidase activity is very low but detectable. The low level of intracellular crosslinked proteins is consistent with tight regulation of transglutaminase activity.
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Onder S, van Grol M, Fidder A, Xiao G, Noort D, Yerramalla U, Tacal O, Schopfer LM, Lockridge O. Rabbit Antidiethoxyphosphotyrosine Antibody, Made by Single B Cell Cloning, Detects Chlorpyrifos Oxon-Modified Proteins in Cultured Cells and Immunopurifies Modified Peptides for Mass Spectrometry. J Proteome Res 2021; 20:4728-4745. [PMID: 34469172 PMCID: PMC8491160 DOI: 10.1021/acs.jproteome.1c00383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
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Chronic low-dose
exposure to organophosphorus pesticides is associated
with the risk of neurodegenerative disease. The mechanism of neurotoxicity
is independent of acetylcholinesterase inhibition. Adducts on tyrosine,
lysine, threonine, and serine can occur after exposure to organophosphorus
pesticides, the most stable being adducts on tyrosine. Rabbit monoclonal
1C6 to diethoxyphosphate-modified tyrosine (depY) was created by single
B cell cloning. The amino acid sequence and binding constant (Kd 3.2 × 10–8 M) were
determined. Cultured human neuroblastoma SH-SY5Y and mouse neuroblastoma
N2a cells incubated with a subcytotoxic dose of 10 μM chlorpyrifos
oxon contained depY-modified proteins detected by monoclonal 1C6 on
Western blots. depY-labeled peptides from tryptic digests of cell
lysates were immunopurified by binding to immobilized 1C6. Peptides
released with 50% acetonitrile and 1% formic acid were analyzed by
liquid chromatography tandem mass spectrometry (LC-MS/MS) on an Orbitrap
Fusion Lumos mass spectrometer. Protein Prospector database searches
identified 51 peptides modified on tyrosine by diethoxyphosphate in
SH-SY5Y cell lysate and 73 diethoxyphosphate-modified peptides in
N2a cell lysate. Adducts appeared most frequently on the cytoskeleton
proteins tubulin, actin, and vimentin. It was concluded that rabbit
monoclonal 1C6 can be useful for studies that aim to understand the
mechanism of neurotoxicity resulting from low-dose exposure to organophosphorus
pesticides.
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Affiliation(s)
- Seda Onder
- Department of Biochemistry, School of Pharmacy, Hacettepe University, Ankara 06100, Turkey
| | - Marco van Grol
- TNO Organisation for Applied Scientific Research, 2280 AA Rijswijk, The Netherlands
| | - Alex Fidder
- TNO Organisation for Applied Scientific Research, 2280 AA Rijswijk, The Netherlands
| | - Gaoping Xiao
- Syd Labs, Inc., Hopkinton, Massachusetts 01748, United States
| | - Daan Noort
- TNO Organisation for Applied Scientific Research, 2280 AA Rijswijk, The Netherlands
| | | | - Ozden Tacal
- Department of Biochemistry, School of Pharmacy, Hacettepe University, Ankara 06100, Turkey
| | - Lawrence M Schopfer
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
| | - Oksana Lockridge
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
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Herrera-Moreno JF, Medina-Díaz IM, Bernal-Hernández YY, Barrón-Vivanco BS, González-Arias CA, Moreno-Godínez ME, Verdín-Betancourt FA, Sierra-Santoyo A, Rojas-García AE. Organophosphorus pesticide exposure biomarkers in a Mexican population. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:50825-50834. [PMID: 33970420 DOI: 10.1007/s11356-021-14270-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/30/2021] [Indexed: 06/12/2023]
Abstract
The organophosphate (OP) pesticides are neurotoxic compounds widely used around the world. Evaluation of OP exposure in human studies is important for enabling adequate data analyses and drawing accurate conclusions. The aim of this study was to analyze OP exposure biomarkers and their relationships in a Mexican population with different exposure levels. Dialkylphosphates (DAP) were determined through gas chromatography-mass spectrometry (GC-MSD); acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), arylesterase (AREase), basal paraoxonase 1 (PONase), and β-glucuronidase activities were detected using spectrophotometric methods. The albumin content was determined in a certified clinical laboratory. The DMTP metabolite was found in the highest concentration, and a negative and significant correlation between DAP and cholinesterase activity was observed. Our results suggested that BuChE is a considerably more sensitive biomarker than AChE. In addition, β-glucuronidase was positively correlated with albumin, BuChE, and PONase. In conclusion, our data strongly support the use of two or more biomarkers of exposure in human monitoring and the application of a strong and validated questionnaire.
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Affiliation(s)
- José Francisco Herrera-Moreno
- Laboratorio de Contaminación y Toxicología Ambiental, Secretaría de Investigación y Posgrado, Universidad Autónoma de Nayarit, Tepic, Nayarit, Mexico
| | - Irma Martha Medina-Díaz
- Laboratorio de Contaminación y Toxicología Ambiental, Secretaría de Investigación y Posgrado, Universidad Autónoma de Nayarit, Tepic, Nayarit, Mexico
| | - Yael Yvette Bernal-Hernández
- Laboratorio de Contaminación y Toxicología Ambiental, Secretaría de Investigación y Posgrado, Universidad Autónoma de Nayarit, Tepic, Nayarit, Mexico
| | - Briscia Socorro Barrón-Vivanco
- Laboratorio de Contaminación y Toxicología Ambiental, Secretaría de Investigación y Posgrado, Universidad Autónoma de Nayarit, Tepic, Nayarit, Mexico
| | - Cyndia Azucena González-Arias
- Laboratorio de Contaminación y Toxicología Ambiental, Secretaría de Investigación y Posgrado, Universidad Autónoma de Nayarit, Tepic, Nayarit, Mexico
| | - Ma Elena Moreno-Godínez
- Laboratorio de Toxicología y Salud Ambiental. Facultad de Ciencias Químico-Biológicas, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico
| | - Francisco Alberto Verdín-Betancourt
- Laboratorio de Contaminación y Toxicología Ambiental, Secretaría de Investigación y Posgrado, Universidad Autónoma de Nayarit, Tepic, Nayarit, Mexico
| | - Adolfo Sierra-Santoyo
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, Mexico
| | - Aurora Elizabeth Rojas-García
- Laboratorio de Contaminación y Toxicología Ambiental, Secretaría de Investigación y Posgrado, Universidad Autónoma de Nayarit, Tepic, Nayarit, Mexico.
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8
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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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Mass Spectrometry Identifies Isopeptide Cross-Links Promoted by Diethylphosphorylated Lysine in Proteins Treated with Chlorpyrifos Oxon. Chem Res Toxicol 2019; 32:762-772. [DOI: 10.1021/acs.chemrestox.9b00001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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Machado SC, Martins I. Risk assessment of occupational pesticide exposure: Use of endpoints and surrogates. Regul Toxicol Pharmacol 2018; 98:276-283. [DOI: 10.1016/j.yrtph.2018.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 07/20/2018] [Accepted: 08/16/2018] [Indexed: 10/28/2022]
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Schopfer LM, Lockridge O. Chlorpyrifos oxon promotes tubulin aggregation via isopeptide cross-linking between diethoxyphospho-Lys and Glu or Asp: Implications for neurotoxicity. J Biol Chem 2018; 293:13566-13577. [PMID: 30006344 PMCID: PMC6120212 DOI: 10.1074/jbc.ra118.004172] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/09/2018] [Indexed: 11/06/2022] Open
Abstract
Exposure to organophosphorus toxicants (OP) can have chronic adverse effects that are not explained by inhibition of acetylcholinesterase, the cause of acute OP toxicity. We therefore hypothesized that OP-induced chronic illness is initiated by the formation of organophosphorus adducts on lysine residues in proteins, followed by protein cross-linking and aggregation. Here, Western blots revealed that exposure to the OP chlorpyrifos oxon converted porcine tubulin from its original 55-kDa mass to high-molecular-weight aggregates. Liquid chromatography–tandem MS analysis of trypsin-digested samples identified several diethoxyphospho-lysine residues in the OP-treated tubulin. Using a search approach based on the Batch Tag program, we identified cross-linked peptides and found that these chemically activated lysines reacted with acidic amino acid residues creating γ-glutamyl-ϵ-lysine or aspartyl-ϵ-lysine isopeptide bonds between β- and α-tubulin. Of note, these cross-linked tubulin molecules accounted for the high-molecular-weight aggregates. To the best of our knowledge, this is the first report indicating that chlorpyrifos oxon–exposed tubulin protein forms intermolecular cross-links with other tubulin molecules, resulting in high-molecular-weight protein aggregates. It is tempting to speculate that chronic illness from OP exposure may be explained by a mechanism that starts with OP adduct formation on protein lysines followed by protein cross-linking. We further speculate that OP-modified or cross-linked tubulin can impair axonal transport, reduce neuron connections, and result in neurotoxicity.
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Affiliation(s)
- Lawrence M Schopfer
- From the Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198-5900
| | - Oksana Lockridge
- From the Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198-5900
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12
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Onder S, Schopfer LM, Tacal O, Blake TA, Johnson RC, Lockridge O. Mass Spectral Detection of Diethoxyphospho-Tyrosine Adducts on Proteins from HEK293 Cells Using Monoclonal Antibody depY for Enrichment. Chem Res Toxicol 2018; 31:520-530. [PMID: 29775289 PMCID: PMC6008731 DOI: 10.1021/acs.chemrestox.8b00083] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Chronic illness from exposure to
organophosphorus toxicants is
hypothesized to involve modification of unknown proteins. Tyrosine
in proteins that have no active site serine readily reacts with organophosphorus
toxicants. We developed a monoclonal antibody, depY, that specifically
recognizes diethoxyphospho-tyrosine in proteins and peptides, independent
of the surrounding amino acid sequence. Our goal in the current study
was to identify diethoxyphosphorylated proteins in human HEK293 cell
lysate treated with chlorpyrifos oxon. Cell lysates treated with chlorpyrifos
oxon were recognized by depY antibody in ELISA and capillary electrophoresis
based Western blot. Tryptic peptides were analyzed by liquid chromatography
tandem mass spectrometry. Liquid chromatography tandem mass spectrometry
identified 116 diethoxyphospho-tyrosine peptides from 73 proteins
in immunopurified samples, but found only 15 diethoxyphospho-tyrosine
peptides from 12 proteins when the same sample was not immunopurified
on depY. The most abundant proteins in the cell lysate, histone H4,
heat shock 70 kDa protein 1A/1B, heat shock protein HSP 90 β,
and α-enolase, were represented by several diethoxyphospho-tyrosine
peptides. It was concluded that use of immobilized depY improved the
number of diethoxyphospho-tyrosine peptides identified in a complex
mixture. The mass spectrometry results confirmed the specificity of
depY for diethoxyphospho-tyrosine peptides independent of the context
of the modified tyrosine, which means depY could be used to analyze
modified proteins in any species. Use of the depY antibody could lead
to an understanding of chronic illness from organophosphorus pesticide
exposure.
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Affiliation(s)
- Seda Onder
- Department of Biochemistry, School of Pharmacy , Hacettepe University , Ankara 06100 , Turkey.,Eppley Institute , University of Nebraska Medical Center , Omaha , Nebraska 68198 , United States
| | - Lawrence M Schopfer
- Eppley Institute , University of Nebraska Medical Center , Omaha , Nebraska 68198 , United States
| | - Ozden Tacal
- Department of Biochemistry, School of Pharmacy , Hacettepe University , Ankara 06100 , Turkey
| | - Thomas A Blake
- Division of Laboratory Sciences, National Center for Environmental Health , Centers for Disease Control and Prevention , 4770 Buford Highway NE , Atlanta , Georgia 30341 , United States
| | - Rudolph C Johnson
- Division of Laboratory Sciences, National Center for Environmental Health , Centers for Disease Control and Prevention , 4770 Buford Highway NE , Atlanta , Georgia 30341 , United States
| | - Oksana Lockridge
- Eppley Institute , University of Nebraska Medical Center , Omaha , Nebraska 68198 , United States
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13
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Onder S, Dafferner AJ, Schopfer LM, Xiao G, Yerramalla U, Tacal O, Blake TA, Johnson RC, Lockridge O. Monoclonal Antibody That Recognizes Diethoxyphosphotyrosine-Modified Proteins and Peptides Independent of Surrounding Amino Acids. Chem Res Toxicol 2017; 30:2218-2228. [PMID: 29137457 DOI: 10.1021/acs.chemrestox.7b00288] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are irreversibly inhibited by organophosphorus pesticides through formation of a covalent bond with the active site serine. Proteins that have no active site serine, for example albumin, are covalently modified on tyrosine and lysine. Chronic illness from pesticide exposure is not explained by inhibition of AChE and BChE. Our goal was to produce a monoclonal antibody that recognizes proteins diethoxyphosphorylated on tyrosine. Diethoxyphosphate-tyrosine adducts for 13 peptides were synthesized. The diethoxyphosphorylated (OP) peptides cross-linked to four different carrier proteins were used to immunize, boost, and screen mice. Monoclonal antibodies were produced with hybridoma technology. Monoclonal antibody depY was purified and characterized by ELISA, western blotting, Biacore, and Octet technology to determine binding affinity and binding specificity. DepY recognized diethoxyphosphotyrosine independent of the amino acid sequence around the modified tyrosine and independent of the identity of the carrier protein or peptide. It had an IC50 of 3 × 10-9 M in a competition assay with OP tubulin. Kd values measured by Biacore and OctetRED96 were 10-8 M for OP-peptides and 1 × 10-12 M for OP-proteins. The limit of detection measured on western blots hybridized with 0.14 μg/mL of depY was 0.025 μg of human albumin conjugated to YGGFL-OP. DepY was specific for diethoxyphosphotyrosine (chlorpyrifos oxon adduct) as it failed to recognize diethoxyphospholysine, phosphoserine, phosphotyrosine, phosphothreonine, dimethoxyphosphotyrosine (dichlorvos adduct), dimethoxyphosphoserine, monomethoxyphosphotyrosine (aged dichlorvos adduct), and cresylphosphoserine. In conclusion, a monoclonal antibody that specifically recognizes diethoxyphosphotyrosine adducts has been developed. The depY monoclonal antibody could be useful for identifying new biomarkers of OP exposure.
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Affiliation(s)
- Seda Onder
- Department of Biochemistry, School of Pharmacy, Hacettepe University , Ankara 06100, Turkey.,Eppley Institute, University of Nebraska Medical Center , Omaha, Nebraska 68198, United States
| | - Alicia J Dafferner
- Eppley Institute, University of Nebraska Medical Center , Omaha, Nebraska 68198, United States
| | - Lawrence M Schopfer
- Eppley Institute, University of Nebraska Medical Center , Omaha, Nebraska 68198, United States
| | - Gaoping Xiao
- Syd Labs, Inc. , Natick, Massachusetts 01760, United States
| | | | - Ozden Tacal
- Department of Biochemistry, School of Pharmacy, Hacettepe University , Ankara 06100, Turkey
| | - Thomas A Blake
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention , 4770 Buford Highway NE, Chamblee, Georgia 30341, United States
| | - Rudolph C Johnson
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention , 4770 Buford Highway NE, Chamblee, Georgia 30341, United States
| | - Oksana Lockridge
- Eppley Institute, University of Nebraska Medical Center , Omaha, Nebraska 68198, United States
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14
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Mohammadi T, Ghayeb Y, Sharifi T, Khayamian T. The effect of dichlorvos on the structural alteration of serum albumins: a combined spectroscopic and molecular dynamic simulation approach. MONATSHEFTE FUR CHEMIE 2016. [DOI: 10.1007/s00706-016-1857-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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15
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Yang X, Bartlett MG. Identification of protein adduction using mass spectrometry: Protein adducts as biomarkers and predictors of toxicity mechanisms. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:652-664. [PMID: 26842586 DOI: 10.1002/rcm.7462] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/12/2015] [Accepted: 11/13/2015] [Indexed: 06/05/2023]
Abstract
The determination of protein-xenobiotic adducts using mass spectrometry is an emerging area which allows detailed understanding of the underlying mechanisms involved in toxicity. These approaches can also be used to reveal potential biomarkers of exposure or toxic response. The following review covers studies of protein adducts resulting from exposure to a wide variety of xenobiotics including organophosphates, polycyclic aromatic hydrocarbons, acetaminophen, alkylating agents and other related compounds.
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Affiliation(s)
- Xiangkun Yang
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, GA, 30602-2352, USA
| | - Michael G Bartlett
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, GA, 30602-2352, USA
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