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Bubik A, Frangež R, Žužek MC, Gutiérrez-Aguirre I, Lah TT, Sedmak B. Cyanobacterial Cyclic Peptides Can Disrupt Cytoskeleton Organization in Human Astrocytes-A Contribution to the Understanding of the Systemic Toxicity of Cyanotoxins. Toxins (Basel) 2024; 16:374. [PMID: 39330832 PMCID: PMC11436104 DOI: 10.3390/toxins16090374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2024] [Revised: 08/13/2024] [Accepted: 08/21/2024] [Indexed: 09/28/2024] Open
Abstract
The systemic toxicity of cyclic peptides produced by cyanobacteria (CCPs) is not yet completely understood. Apart from the most known damages to the liver and kidneys, symptoms of their neurotoxicity have also been reported. Hepatotoxic CCPs, like microcystins, as well as non-hepatotoxic anabaenopeptins and planktopeptins, all exhibit cytotoxic and cytostatic effects on mammalian cells. However, responses of different cell types to CCPs depend on their specific modes of interaction with cell membranes. This study demonstrates that non-hepatotoxic planktopeptin BL1125 and anabaenopeptins B and F, at concentrations up to 10 µM, affect normal and tumor human astrocytes (NHA and U87-GM) in vitro by their almost immediate insertion into the lipid monolayer. Like microcystin-LR (up to 1 µM), they inhibit Ser/Thr phosphatases and reorganize cytoskeletal elements, with modest effects on their gene expression. Based on the observed effects on intermediate filaments and intermediate filament linkage elements, their direct or indirect influence on tubulin cytoskeletons via post-translational modifications, we conclude that the basic mechanism of CCP toxicities is the induction of inter- and intracellular communication failure. The assessed inhibitory activity on Ser/Thr phosphatases is also crucial since the signal transduction cascades are modulated by phosphorylation/dephosphorylation processes.
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Affiliation(s)
- Anja Bubik
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Večna pot 121, SI-1000 Ljubljana, Slovenia
- Faculty of Environmental Protection, Trg mladosti 7, SI-3320 Velenje, Slovenia
| | - Robert Frangež
- Institute of Preclinical Sciences, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana, Slovenia
| | - Monika C Žužek
- Institute of Preclinical Sciences, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana, Slovenia
| | - Ion Gutiérrez-Aguirre
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 121, SI-1000 Ljubljana, Slovenia
| | - Tamara T Lah
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Večna pot 121, SI-1000 Ljubljana, Slovenia
| | - Bojan Sedmak
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Večna pot 121, SI-1000 Ljubljana, Slovenia
- Faculty of Environmental Protection, Trg mladosti 7, SI-3320 Velenje, Slovenia
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Arman T, Clarke JD. Microcystin Toxicokinetics, Molecular Toxicology, and Pathophysiology in Preclinical Rodent Models and Humans. Toxins (Basel) 2021; 13:toxins13080537. [PMID: 34437407 PMCID: PMC8402503 DOI: 10.3390/toxins13080537] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 07/23/2021] [Accepted: 07/27/2021] [Indexed: 02/06/2023] Open
Abstract
Microcystins are ubiquitous toxins produced by photoautotrophic cyanobacteria. Human exposures to microcystins occur through the consumption of contaminated drinking water, fish and shellfish, vegetables, and algal dietary supplements and through recreational activities. Microcystin-leucine-arginine (MCLR) is the prototypical microcystin because it is reported to be the most common and toxic variant and is the only microcystin with an established tolerable daily intake of 0.04 µg/kg. Microcystin toxicokinetics is characterized by low intestinal absorption, rapid and specific distribution to the liver, moderate metabolism to glutathione and cysteinyl conjugates, and low urinary and fecal excretion. Molecular toxicology involves covalent binding to and inhibition of protein phosphatases, oxidative stress, cell death (autophagy, apoptosis, necrosis), and cytoskeleton disruption. These molecular and cellular effects are interconnected and are commonly observed together. The main target organs for microcystin toxicity are the intestine, liver, and kidney. Preclinical data indicate microcystins may also have nervous, pulmonary, cardiac, and reproductive system toxicities. Recent evidence suggests that exposure to other hepatotoxic insults could potentiate microcystin toxicity and increase the risk for chronic diseases. This review summarizes the current knowledge for microcystin toxicokinetics, molecular toxicology, and pathophysiology in preclinical rodent models and humans. More research is needed to better understand human toxicokinetics and how multifactorial exposures contribute to disease pathogenesis and progression.
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Chronic Low Dose Oral Exposure to Microcystin-LR Exacerbates Hepatic Injury in a Murine Model of Non-Alcoholic Fatty Liver Disease. Toxins (Basel) 2019; 11:toxins11090486. [PMID: 31450746 PMCID: PMC6783870 DOI: 10.3390/toxins11090486] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/15/2019] [Accepted: 08/19/2019] [Indexed: 12/17/2022] Open
Abstract
Microcystins are potent hepatotoxins that have become a global health concern in recent years. Their actions in at-risk populations with pre-existing liver disease is unknown. We tested the hypothesis that the No Observed Adverse Effect Level (NOAEL) of Microcystin-LR (MC-LR) established in healthy mice would cause exacerbation of hepatic injury in a murine model (Leprdb/J) of Non-alcoholic Fatty Liver Disease (NAFLD). Ten-week-old male Leprdb/J mice were gavaged with 50 μg/kg, 100 μg/kg MC-LR or vehicle every 48 h for 4 weeks (n = 15–17 mice/group). Early mortality was observed in both the 50 μg/kg (1/17, 6%), and 100 μg/kg (3/17, 18%) MC-LR exposed mice. MC-LR exposure resulted in significant increases in circulating alkaline phosphatase levels, and histopathological markers of hepatic injury as well as significant upregulation of genes associated with hepatotoxicity, necrosis, nongenotoxic hepatocarcinogenicity and oxidative stress response. In addition, we observed exposure dependent changes in protein phosphorylation sites in pathways involved in inflammation, immune function, and response to oxidative stress. These results demonstrate that exposure to MC-LR at levels that are below the NOAEL established in healthy animals results in significant exacerbation of hepatic injury that is accompanied by genetic and phosphoproteomic dysregulation in key signaling pathways in the livers of NAFLD mice.
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Arman T, Lynch KD, Montonye ML, Goedken M, Clarke JD. Sub-Chronic Microcystin-LR Liver Toxicity in Preexisting Diet-Induced Nonalcoholic Steatohepatitis in Rats. Toxins (Basel) 2019; 11:E398. [PMID: 31323923 PMCID: PMC6669744 DOI: 10.3390/toxins11070398] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/02/2019] [Accepted: 07/04/2019] [Indexed: 02/07/2023] Open
Abstract
Microcystin-LR (MCLR) is a hepatotoxic cyanotoxin reported to cause a phenotype similar to nonalcoholic steatohepatitis (NASH). NASH is a common progressive liver disease that advances in severity due to exogenous stressors such as poor diet and toxicant exposure. Our objective was to determine how sub-chronic MCLR toxicity affects preexisting diet-induced NASH. Sprague-Dawley rats were fed one of three diets for 10 weeks: control, methionine and choline deficient (MCD), or high fat/high cholesterol (HFHC). After six weeks of diet, animals received vehicle, 10 µg/kg, or 30 µg/kg MCLR via intraperitoneal injection every other day for the final 4 weeks. Incidence and severity scoring of histopathology endpoints suggested that MCLR toxicity drove NASH to a less fatty and more fibrotic state. In general, expression of genes involved in de novo lipogenesis and fatty acid esterification were altered in favor of decreased steatosis. The higher MCLR dose increased expression of genes involved in fibrosis and inflammation in the control and HFHC groups. These data suggest MCLR toxicity in the context of preexisting NASH may drive the liver to a more severe phenotype that resembles burnt-out NASH.
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Affiliation(s)
- Tarana Arman
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA 99202, USA
| | - Katherine D Lynch
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA 99202, USA
| | - Michelle L Montonye
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA 99202, USA
| | - Michael Goedken
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ 08901, USA
| | - John D Clarke
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA 99202, USA.
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Moreira DA, Soares RM, Valente RH, Bebianno MJ, Rebelo MF. Molecular effects of Microcystin-LA in tilapia (Oreochromis niloticus). Toxicon 2019; 166:76-82. [PMID: 31121173 DOI: 10.1016/j.toxicon.2019.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 04/25/2019] [Accepted: 05/11/2019] [Indexed: 10/26/2022]
Abstract
Nile tilapia (Oreochromis niloticus) is a freshwater phytoplanktivorous fish species reported to accumulate and tolerate large amounts of cyanotoxins such as microcystins (MCs). The present study aimed to investigate molecular responses to the acute exposure of Nile tilapia to the Microcystin-LA analogue (MC-LA). Thus, the specimens were sublethally exposed to 1000 μg kg-1 of MC-LA for 12, 24, 48, and 96 h. Gene expression of PP1, PP2A, GST, GPX and actin was analyzed by quantitative PCR. The protein abundance profile of PP2A was determined by immunoblotting, while the integrity of its biological function was assessed by a phosphatase enzymatic assay. PP2A activity was significantly and strongly reduced by MC-LA. A resulting feedback mechanism significantly increased PP2A gene expression and protein abundance in all assessed times. However, a recovery of that phosphatase activity was not observed. In this study, the observed increase in GPX gene expression was the only response that could be directly related to the unknown factors associated to the fish survival to such high dose exposure.
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Affiliation(s)
- Daniel A Moreira
- Laboratory of Environmental Molecular Biology, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Graduate Program in Computational and Systems Biology, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Raquel M Soares
- Multidisciplinary Center of Research in Biology - NUMPEX-BIO - Campus Duque de Caxias, Universidade Federal do Rio de Janeiro, Duque de Caxias, RJ, Brazil.
| | - Richard H Valente
- Laboratory of Toxinology, Instituto Oswaldo Cruz. Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Maria J Bebianno
- Laboratory of Environmental Molecular Biology, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; CIMA, University of Algarve, Campus de Gambelas, 8000-397, Faro, Portugal
| | - Mauro F Rebelo
- Laboratory of Environmental Molecular Biology, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Clarke JD, Dzierlenga A, Arman T, Toth E, Li H, Lynch KD, Tian DD, Goedken M, Paine MF, Cherrington N. Nonalcoholic fatty liver disease alters microcystin-LR toxicokinetics and acute toxicity. Toxicon 2019; 162:1-8. [PMID: 30849452 PMCID: PMC6447445 DOI: 10.1016/j.toxicon.2019.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 02/27/2019] [Accepted: 03/03/2019] [Indexed: 02/08/2023]
Abstract
Microcystin-LR (MCLR) is a cyanotoxin produced by blue-green algae that causes liver and kidney toxicities. MCLR toxicity is dependent on cellular uptake through the organic anion transporting polypeptide (OATP) transporters. Nonalcoholic fatty liver disease (NAFLD) progresses through multiple stages, alters expression of hepatic OATPs, and is associated with chronic kidney disease. The purpose of this study was to determine whether NAFLD increases systemic exposure to MCLR and influences acute liver and kidney toxicities. Rats were fed a control diet or two dietary models of NAFLD; methionine and choline deficient (MCD) or high fat/high cholesterol (HFHC). Two studies were performed in these groups: 1) a single dose intravenous toxicokinetic study (20 μg/kg), and 2) a single dose intraperitoneal toxicity study (60 μg/kg). Compared to control rats, plasma MCLR area under the concentration-time curve (AUC) in MCD rats doubled, whereas biliary clearance (Clbil) was unchanged; in contrast, plasma AUC in HFHC rats was unchanged, whereas Clbil approximately doubled. Less MCLR bound to PP2A was observed in the liver of MCD rats. This shift in exposure decreased the severity of liver pathology only in the MCD rats after a single toxic dose of MCLR (60 μg/kg). In contrast, the single toxic dose of MCLR increased hepatic inflammation, plasma cholesterol, proteinuria, and urinary KIM1 in HFHC rats more than MCLR exposed control rats. In conclusion, rodent models of NAFLD alter MCLR toxicokinetics and acute toxicity and may have implications for liver and kidney pathologies in NAFLD patients.
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Affiliation(s)
- John D Clarke
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99202, USA.
| | - Anika Dzierlenga
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, 85721, USA
| | - Tarana Arman
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99202, USA
| | - Erica Toth
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, 85721, USA
| | - Hui Li
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, 85721, USA
| | - Katherine D Lynch
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99202, USA
| | - Dan-Dan Tian
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99202, USA
| | - Michael Goedken
- Rutgers Translational Sciences, Rutgers University, Piscataway, NJ, 08901, USA
| | - Mary F Paine
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99202, USA
| | - Nathan Cherrington
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, 85721, USA
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Zhao J, Tian F, Zhai Q, Yu R, Zhang H, Gu Z, Chen W. Protective effects of a cocktail of lactic acid bacteria on microcystin-LR-induced hepatotoxicity and oxidative damage in BALB/c mice. RSC Adv 2017. [DOI: 10.1039/c7ra03035e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The aim of this study was to investigate the effects of mixed lactic acid bacteria (LAB) against microcystin-LR-exposed hepatotoxicity and oxidative stress in BALB/c mice.
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Affiliation(s)
- Jichun Zhao
- State Key Laboratory of Food Science and Technology
- School of Food Science and Technology
- Jiangnan University
- Wuxi 214122
- P. R. China
| | - Fengwei Tian
- State Key Laboratory of Food Science and Technology
- School of Food Science and Technology
- Jiangnan University
- Wuxi 214122
- P. R. China
| | - Qixiao Zhai
- State Key Laboratory of Food Science and Technology
- School of Food Science and Technology
- Jiangnan University
- Wuxi 214122
- P. R. China
| | - Ruipeng Yu
- State Key Laboratory of Food Science and Technology
- School of Food Science and Technology
- Jiangnan University
- Wuxi 214122
- P. R. China
| | - Hao Zhang
- State Key Laboratory of Food Science and Technology
- School of Food Science and Technology
- Jiangnan University
- Wuxi 214122
- P. R. China
| | - Zhennan Gu
- State Key Laboratory of Food Science and Technology
- School of Food Science and Technology
- Jiangnan University
- Wuxi 214122
- P. R. China
| | - Wei Chen
- State Key Laboratory of Food Science and Technology
- School of Food Science and Technology
- Jiangnan University
- Wuxi 214122
- P. R. China
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Bownik A. Harmful algae: Effects of cyanobacterial cyclic peptides on aquatic invertebrates-a short review. Toxicon 2016; 124:S0041-0101(16)30319-1. [PMID: 27984061 DOI: 10.1016/j.toxicon.2016.10.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/24/2016] [Accepted: 10/27/2016] [Indexed: 12/22/2022]
Abstract
Cyanotoxins are secondary metabolites produced by cyanobacteria. Cyclic peptides, microcystins and nodularin commonly detected in water reservoirs of different parts of the world may induce various detrimental effects in a wide range of organisms from bacteria to humans. This paper presents the current state of knowledge on the effects of microcystins and nodularin on aquatic invertebrates: zooplankton, decapods and mollusks. Accumulation of microcystins and nodularin in these organisms and possible transfer of the cyanotoxins through the food web and possible threat to humans as consumers are also discussed.
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Affiliation(s)
- Adam Bownik
- Department of Biological Basis of Animal Production, University of Life Sciences, Akademicka 13 Str., 20-950 Lublin, Poland.
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Yuan J, Gu Z, Zheng Y, Zhang Y, Gao J, Chen S, Wang Z. Accumulation and detoxification dynamics of microcystin-LR and antioxidant responses in male red swamp crayfish Procambarus clarkii. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 177:8-18. [PMID: 27218425 DOI: 10.1016/j.aquatox.2016.05.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 04/30/2016] [Accepted: 05/06/2016] [Indexed: 06/05/2023]
Abstract
MC-LR is one of major microcystin isoforms with potent hepatotoxicity. In the present study, we aim to: 1) explore the dynamics of MC-LR accumulation and elimination in different tissues of male red swamp crayfish Procambarus clarkii; 2) reveal the mechanisms underlying hepatic antioxidation and detoxification. In the semi-static toxicity tests under the water temperature of 25±2°C, P. clarkii were exposed to 0.1, 1, 10 and 100μg/L MC-LR for 7days for accumulation and subsequently relocated to freshwater for another 7days to depurate MC-LR. MC-LR was measured in the hepatopancreas, intestine, abdominal muscle and gill by HPLC. The enzyme activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST), content of glutathione (GSH), and transcripts of Mn-sod, cat, gpx1, Mu-gst, heat shock protein90 (hsp90), hsp70 and hsp60 in hepatopancreas were detected. The results showed that P. clarkii accumulated more MC-LR in intestine, and less in abdominal muscle and gill during accumulation period and eliminated the toxin more quickly in gill and abdominal muscle, and comparatively slowly in intestine during depuration period. The fast increase of SOD and CAT activities at early stage, subsequent decrease at later stage of accumulation period and then fast increase during depuration period were partially consistent with the transcriptional changes of their respective genes. GPx was activated by longer MC-LR exposure and gpx1 mRNA expression showed uncoordinated regulation pattern compared with its enzyme. Hsp genes were up-regulated when P. clarkii was exposed to MC-LR.
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Affiliation(s)
- Julin Yuan
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China; Zhejiang Institute of Freshwater Fisheries, Freshwater Fishery Healthy Breeding Laboratory of Ministry of Agriculture, Huzhou, Zhejiang 313001, China
| | - Zhimin Gu
- Zhejiang Institute of Freshwater Fisheries, Freshwater Fishery Healthy Breeding Laboratory of Ministry of Agriculture, Huzhou, Zhejiang 313001, China.
| | - Yao Zheng
- Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences; Scientific Observing and Experimental Station of Fishery Resources and Environment in the Lower Reaches of the Changjiang River, Wuxi 214081, China
| | - Yingying Zhang
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China
| | - Jiancao Gao
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China
| | - Shu Chen
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China
| | - Zaizhao Wang
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China.
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Cell Death Inducing Microbial Protein Phosphatase Inhibitors--Mechanisms of Action. Mar Drugs 2015; 13:6505-20. [PMID: 26506362 PMCID: PMC4626703 DOI: 10.3390/md13106505] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/12/2015] [Accepted: 10/15/2015] [Indexed: 02/07/2023] Open
Abstract
Okadaic acid (OA) and microcystin (MC) as well as several other microbial toxins like nodularin and calyculinA are known as tumor promoters as well as inducers of apoptotic cell death. Their intracellular targets are the major serine/threonine protein phosphatases. This review summarizes mechanisms believed to be responsible for the death induction and tumor promotion with focus on the interdependent production of reactive oxygen species (ROS) and activation of Ca2+/calmodulin kinase II (CaM-KII). New data are presented using inhibitors of specific ROS producing enzymes to curb nodularin/MC-induced liver cell (hepatocyte) death. They indicate that enzymes of the arachidonic acid pathway, notably phospholipase A2, 5-lipoxygenase, and cyclooxygenases, may be required for nodularin/MC-induced (and presumably OA-induced) cell death, suggesting new ways to overcome at least some aspects of OA and MC toxicity.
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Potential role of engineered nanoparticles as contaminant carriers in aquatic ecosystems: Estimating sorption processes of the cyanobacterial toxin microcystin-LR by TiO2 nanoparticles. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2015.06.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Contardo-Jara V, Kuehn S, Pflugmacher S. Single and combined exposure to MC-LR and BMAA confirm suitability of Aegagropila linnaei for use in green liver systems(®)-A case study with cyanobacterial toxins. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2015; 165:101-108. [PMID: 26037095 DOI: 10.1016/j.aquatox.2015.05.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/04/2015] [Accepted: 05/17/2015] [Indexed: 06/04/2023]
Abstract
The filamentous green algae Aegagropila linnaei was tested for its uptake capacity of the cyanobacterial toxins microcystin-LR (MC-LR) and β-N-methylamino-l-alanine (BMAA) in order to approve the suitability of its use in the Green Liver System(®). Uptake into the algae and toxin reduction in the medium were analyzed by LC-MS/MS after static exposure for one week to 20μgL(-1) MC-LR, 80μgL(-1) BMAA, and 20μgL(-1) MC-LR together with 80μgL(-1) BMAA, respectively. BMAA was effectively removed by A. linnaei within 5 days compared to only around 35% removal of the initial exposure concentration in the case of MC-LR, independent of the application mode, in single or in a mixture. However, differences were found for BMAA amounts taken up into the tissue in that it was higher if applied in combination with MC-LR. Additionally, physiological responses such as the activity of biotransformation enzyme glutathione S-transferase (GST), antioxidant enzymes peroxidase (POD) and catalase (CAT) as well as the development of the reactive oxygen species hydrogen peroxide (H2O2) were compared between the different treatment groups in order to determine possible harmful effects of the toxin exposure on the algae. In contrast to the toxin exposure to a single toxin with no significant enzymatic response, exposure to the toxin mixture provoked an immediate increase in GST and CAT activity after one day as well as after longer exposure for one week, hinting on an enhanced need for prevention against exposure derived reactive oxygen species as well as putative biotransformation attempts in a mixture exposure scenario.
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Affiliation(s)
- Valeska Contardo-Jara
- Technische Universität Berlin, Institute of Ecology, Department Ecological Impact Research and Ecotoxicology, Ernst-Reuter-Platz 1, 10587 Berlin, Germany.
| | - Sandra Kuehn
- Technische Universität Berlin, Institute of Ecology, Department Ecological Impact Research and Ecotoxicology, Ernst-Reuter-Platz 1, 10587 Berlin, Germany.
| | - Stephan Pflugmacher
- Technische Universität Berlin, Institute of Ecology, Department Ecological Impact Research and Ecotoxicology, Ernst-Reuter-Platz 1, 10587 Berlin, Germany.
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13
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Fan H, Cai Y, Xie P, Xiao W, Chen J, Ji W, Zhao S. Microcystin-LR stabilizes c-myc protein by inhibiting protein phosphatase 2A in HEK293 cells. Toxicology 2014; 319:69-74. [DOI: 10.1016/j.tox.2014.02.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 02/24/2014] [Accepted: 02/26/2014] [Indexed: 12/14/2022]
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14
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Gągała I, Izydorczyk K, Jurczak T, Pawełczyk J, Dziadek J, Wojtal-Frankiewicz A, Jóźwik A, Jaskulska A, Mankiewicz-Boczek J. Role of environmental factors and toxic genotypes in the regulation of microcystins-producing cyanobacterial blooms. MICROBIAL ECOLOGY 2014; 67:465-79. [PMID: 24241584 DOI: 10.1007/s00248-013-0303-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Accepted: 09/30/2013] [Indexed: 05/23/2023]
Abstract
The aim of this study was to understand: (1) how environmental conditions can contribute to formation of Microcystis-dominated blooms in lowland, dam reservoirs in temperate climate-with the use of quantitative molecular monitoring, and (2) what is the role of toxic Microcystis genotypes in the bloom functioning. Monitoring of the Sulejow Reservoir in 2009 and 2010 in two sites Tresta (TR) and Bronislawow BR), which have different morphometry, showed that physicochemical conditions were always favorable for cyanobacterial bloom formation. In 2009, the average biomass of cyanobacteria reached 13 mg L(-1) (TR) and 8 mg L(-1) (BR), and in the second year, it decreased to approximately 1 mg L(-1) (TR and BR). In turns, the mean number of toxic Microcystis genotypes in the total Microcystis reached 1% in 2009, both in TR and BR, and in 2010, the number increased to 70% in TR and 14 % in BR. Despite significant differences in the biomass of cyanobacteria in 2009 and 2010, the mean microcystins (MCs) concentration and toxicity stayed at a similar level of approximately 1 μg L(-1). Statistical analysis indicated that water retention time was a factor that provided a significant difference between the two monitoring seasons and was considered a driver of the changes occurring in the Sulejow Reservoir. Hydrologic differences, which occurred between two studied years due to heavy flooding in Poland in 2010, influenced the decrease in number of Microcystis biomass by causing water disturbances and by lowering water temperature. Statistical analysis showed that Microcystis aeruginosa biomass and 16S rRNA gene copy number representing Microcystis genotypes in both years of monitoring could be predicted on the basis of total and dissolved phosphorus concentrations and water temperature. In present study, the number of mcyA gene copies representing toxic Microcystis genotypes could be predicted based on the biomass of M. aeruginosa. Moreover, MCs toxicity and concentration could be predicted on the basic of mcyA gene copy number and M. aeruginosa (biomass, 16S rRNA), respectively. Present findings may indicate that Microcystis can regulate the number of toxic genotypes, and in this way adjust the whole bloom to be able to produce MCs at the level which is necessary for its maintenance in the Sulejow Reservoir under stressful hydrological conditions.
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Affiliation(s)
- Ilona Gągała
- European Regional Centre for Ecohydrology of the Polish Academy of Sciences, Tylna 3, 90-364, Lodz, Poland,
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15
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Qiao Q, Liu W, Wu K, Song T, Hu J, Huang X, Wen J, Chen L, Zhang X. Female zebrafish (Danio rerio) are more vulnerable than males to microcystin-LR exposure, without exhibiting estrogenic effects. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 142-143:272-282. [PMID: 24076620 DOI: 10.1016/j.aquatox.2013.07.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 07/04/2013] [Accepted: 07/07/2013] [Indexed: 06/02/2023]
Abstract
Microcystins (MCs) released during cyanobacterial blooms exert varied toxicity on fish. Up to now, the reproductive toxicity of MCs on fish has rarely been reported. The present study investigated the reproductive toxicity of microcystin-LR (MC-LR) on male and female zebrafish (Danio rerio) by subchronic immersion in 1, 5, 20 μg/L for 30 d. After MC-LR exposure, the hatchability and the 17 beta-estradiol (E2) concentration in gonads significantly decreased in the 20 μg/L group. In the 5 and 20 μg/L groups, the whole body vitellogenin (VTG) levels significantly increased in females, while considerably decreased in males. The VTG1 transcriptional level significantly reduced in the liver of both female and male treated fish. Marked histological lesions were observed in the livers, ovaries and testes in MC-LR treated fish. Apoptotic rate in the ovaries significantly increased. Significant down-regulation of Bcl-2 transcriptional level was found in the gonads of all MC-LR treated fish, while marked up-regulation of Bax transcription level was determined in the 20 μg/L female treatment group, but a significant down-regulation in males. Although the transcriptional level of caspase-3 dropped in ovaries of the 5 and 20 μg/L treatment groups, the significant increase of caspase-3 activation levels in the ovaries and testes were detected. The present findings indicate that MC-LR exposure exerts diverse reproductive toxicity in zebrafish with females exhibiting more sensitivity than males. The present study also confirmed for the first time that MC-LR does not cause any estrogenic effects in adult zebrafish.
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Affiliation(s)
- Qin Qiao
- Fisheries College of Huazhong Agricultural University, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, People's Republic of China
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16
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Renal accumulation and effects of intraperitoneal injection of extracted microcystins in omnivorous crucian carp (Carassius auratus). Toxicon 2013; 70:62-9. [DOI: 10.1016/j.toxicon.2013.03.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Revised: 03/18/2013] [Accepted: 03/28/2013] [Indexed: 11/18/2022]
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17
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Zhang X, Scialis RJ, Feng B, Leach K. Detection of statin cytotoxicity is increased in cells expressing the OATP1B1 transporter. Toxicol Sci 2013; 134:73-82. [PMID: 23564645 DOI: 10.1093/toxsci/kft085] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cytotoxicity of a compound is determined by the intracellular concentration mediated both by passive permeability and active uptake through drug transporters. However, the major liver uptake transporters were either absent or expressed at significantly lower levels in human liver cell lines than in human liver. When comparing cytotoxicity of five statins, the organic anion transporting polypeptide 1B1 expressing HEK cells showed a significantly higher sensitivity than the wild-type HEK cells. The IC50 shifts ranged from 9- to >100-fold, and the potency shifts collapsed in the presence of rifampicin, the inhibitor for OATPs. The extent of the IC50 shift correlated with the permeability of the statins with high permeable compounds having smaller shifts and low permeable compounds having larger shifts. The changes in statin potency in transporter-transfected cells reflect the active uptake of statins into the cells, and the increased intracellular drug concentration lead to increased toxicity. The data suggested that uptake transporters have a significant impact on the outcomes of a cell-based assay and should be considered during the early stages of compound toxicity screening in drug discovery. For compounds with low permeability that are likely to undergo transporter-mediated uptake, it is important to test them in transporter-competent cell models.
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Pantelić D, Svirčev Z, Simeunović J, Vidović M, Trajković I. Cyanotoxins: characteristics, production and degradation routes in drinking water treatment with reference to the situation in Serbia. CHEMOSPHERE 2013; 91:421-441. [PMID: 23391374 DOI: 10.1016/j.chemosphere.2013.01.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 12/26/2012] [Accepted: 01/02/2013] [Indexed: 06/01/2023]
Abstract
Cyanobacteria are members of phytoplankton of the surface freshwaters. The accelerated eutrophication of freshwaters, especially reservoirs for drinking water, by human activity has increased the occurrence and intensity of cyanobacterial blooms. They are of concern due to their ability to produce taste and odors compounds, a wide range of toxins, which have a hepatotoxic, neurotoxic, cytotoxic and dermatotoxic behavior, being dangerous to animal and human health. Therefore, the removal of cyanobacteria, without cell lysis, and releasing of intracellular metabolites, would significantly reduce the concentration of these metabolites in the finished drinking water, as a specific aim of the water treatment processes. This review summarizes the existing data on characteristics of the cyanotoxins, their productions in environment and effective treatment processes to remove these toxins from drinking water.
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Affiliation(s)
- Dijana Pantelić
- University of Novi Sad, Department of Biology and Ecology, Faculty of Sciences, Trg Dositeja Obradovića 2, 21000 Novi Sad, Serbia.
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Sedan D, Giannuzzi L, Rosso L, Marra CA, Andrinolo D. Biomarkers of prolonged exposure to microcystin-LR in mice. Toxicon 2013; 68:9-17. [PMID: 23506857 DOI: 10.1016/j.toxicon.2013.03.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 02/27/2013] [Accepted: 03/01/2013] [Indexed: 01/09/2023]
Abstract
The effects of prolonged exposure to microcystins (MCs) on health are not yet sufficiently understood and this type of poisoning is often undiagnosed. Even though chronic exposure has been linked with liver cancer and alterations have been described in liver damage marker enzymes in exposed populations, there are not profile parameters that indicate prolonged exposure to microcystins. The aim of this work is to determine, based on an animal model of prolonged exposure to successive i.p. doses of 25 μg MC-LR/kg body weight, several plasma parameters which could be useful as exposure biomarkers. Hemoglobin (Hb) and methemoglobin (MetHb) levels were determined on blood samples. We also studied plasma levels of hydroperoxides (ROOHs), α-tocopherol, glutathione and lipid profile as well as superoxide dismutase (SOD) and catalase (CAT) erythrocyte activities. In addition, the determination of MC-LR levels in liver, kidney, plasma, urine and feces of treated mice was carried out. We found that alteration in MetHb, ROOHs, glutathione, α-tocopherol levels, SOD activity and plasma lipid profile, correlates with those expected if the alteration derived from hepatic damage. The alterated plasma paramenters together with MC-LR determination could be used as biomarkers, helpful tools in screening and epidemiological studies.
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Affiliation(s)
- Daniela Sedan
- Área de Toxicología, Facultad de Ciencias Exactas, Universidad Nacional de La Plata UNLP, 1900 La Plata, Argentina
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20
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Burmester V, Nimptsch J, Wiegand C. Adaptation of freshwater mussels to cyanobacterial toxins: response of the biotransformation and antioxidant enzymes. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2012; 78:296-309. [PMID: 22172521 DOI: 10.1016/j.ecoenv.2011.11.037] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 11/25/2011] [Accepted: 11/26/2011] [Indexed: 05/31/2023]
Abstract
Freshwater mussels such as the invasive Dreissena polymorpha and the indigenous Unio tumidus nourish by high filtration rates and may accumulate cyanobacteria and their toxins during cyanobacterial blooms. Physiological adaptations to cyanotoxins enable organisms to endure cyanobacterial blooms but may differ between species. Biotransformation and excretion capacities for cyanobacteria and anthropogenic pollutants have been demonstrated for Dreissena polymorpha but less for unionid species. This study compares the activities of biotransformation (glutathione S-transferase, GST) and antioxidant enzymes (superoxide dismutase, SOD and catalase, CAT) in Dreissena polymorpha to Unio tumidus in response to cyanotoxin exposure (10 μg L(-1) and 50 μg L(-1) microcystin-LR, respectively, total microcystin from a cyanobacterial crude extract) for 24 h and 7d exposure duration. Enzyme activities in Dreissena polymorpha were measured in the whole mussel tissue, digestive gland and in gills and in Unio tumidus in the digestive gland, gills, mantle, foot as well as in the remaining tissue. The sGST was elevated for the entire exposure period in the whole mussel tissue of Dreissena polymorpha but despite higher basal activities in digestive gland and gills of Unio tumidus, it was rather inhibited or unaltered in most of their tissues. Elevated SOD activity indicated oxidative stress response in Dreissena polymorpha, but not in Unio tumidus. The CAT activity was barely affected in both species, rather inhibited in Unio tumidus, despite again higher basal activities in digestive gland and remaining tissue. Compared to the indigenous Unio tumidus, the investigated biotransformation and oxidative stress combating enzymes respond stronger in the invasive Dreissena polymorpha.
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Affiliation(s)
- Vanessa Burmester
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept. Ecophysiology and Aquaculture, Müggelseedamm 301, 12587 Berlin, Germany
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21
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Lezcano N, Sedán D, Lucotti I, Giannuzzi L, Vittone L, Andrinolo D, Mundiña-Weilenmann C. Subchronic microcystin-lr exposure increased hepatic apoptosis and induced compensatory mechanisms in mice. J Biochem Mol Toxicol 2012; 26:131-8. [DOI: 10.1002/jbt.20419] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 10/20/2011] [Accepted: 11/04/2011] [Indexed: 01/19/2023]
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22
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Cui Z, Zhang K, Qu X, Liu Q. Construction of differentially expressed genes library of bighead carp (Aristichthys nobilis) exposed to microcystin-lr using ssh and expression profile of related genes. FISH & SHELLFISH IMMUNOLOGY 2011; 31:746-753. [PMID: 21803161 DOI: 10.1016/j.fsi.2011.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 06/28/2011] [Accepted: 07/09/2011] [Indexed: 05/31/2023]
Abstract
Microcystins (MCs) are hepatotoxic cyclic heptapeptides produced by cyanobacteria (blue-green algae). There are more than 70 MCs variants of which the most common and widely studied is MC-LR. We screened the hepatocellular differentially expressed genes against MC-LR in the bighead carp (Aristichthys nobilis). Suppression subtractive hybridization was used to construct the forward subtracted and reverse subtracted cDNA libraries, and one hundred and thirty two positive clones (seventy one in forward library and sixty one in reverse library) were randomly selected and sequenced. Finally, fifty five reliable sequences from the forward subtracted library were used in a homology search by BLASTn and BLASTx, as were 57 reliable sequences from the reverse subtracted library. Furthermore, eight analyzed sequences from the forward subtracted cDNA library and seven from the reverse subtracted library were found to be non-homologous sequences. The screening identified genes induced by MC-LR in both libraries that are involved in various processes, such as energy metabolism, immunity, and apoptosis. Some are cytoskeleton- and transportation-related genes, while signal transduction-related genes were also found. Significant genes, such as the apoptosis-related gene p53 and the proto-oncogene c-myc, are involved in inhibition of the MC-LR response in the reverse subtracted library. In addition, several immune-related genes, which play an important role in antioxidation and detoxification of MC-LR, were characterized and identified in both of the subtracted libraries. The study provides the basic data to further identify the genes and molecular mechanism of detoxification of microcystins.
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Affiliation(s)
- Zhihui Cui
- College of Fisheries and Life Sciences, Shanghai Ocean University, 999, Hucheng Huan Road, Shanghai, PR China
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23
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Filer CN. Tritiated dihydro compounds employed as radioligand surrogates. J Labelled Comp Radiopharm 2011. [DOI: 10.1002/jlcr.1928] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Crist N. Filer
- PerkinElmer Health Sciences Inc.; 940 Winter Street; Waltham; MA; 02451; USA
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Pathological modifications following sub-chronic exposure of medaka fish (Oryzias latipes) to microcystin-LR. Reprod Toxicol 2011; 32:329-40. [PMID: 21839164 DOI: 10.1016/j.reprotox.2011.07.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 06/15/2011] [Accepted: 07/25/2011] [Indexed: 12/29/2022]
Abstract
Microcystins (MCs) are toxic monocyclic heptapeptides produced by many cyanobacteria. MCs, especially MC-LR, cause toxic effects in animals and are a recognized potent cause of environmental stress and health hazard in aquatic ecosystems when heavy blooms of cyanobacteria appear. Consequently, one of the major problems is the chronic exposure of fish to cyanotoxins in their natural environment. The present experiment involving chronic exposure confirmed initial findings on acute exposure to MC contamination: exacerbated physiological stress and tissue damage in several tissues of exposed medaka fish. The gonads were affected specifically. In female gonads the modifications included reduction of the vitellus storage, lysis of the gonadosomatic tissue and disruption of the relationships between the follicular cells and the oocytes. In the males, spermatogenesis appeared to be disrupted. This is the first report showing that a cyanotoxin can affect reproductive function, and so can impact on fish reproduction and thus fish stocks.
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Labine M, Minuk G. Cyanobacterial toxins and liver diseaseThis article is one of a selection of papers published in a special issue celebrating the 125th anniversary of the Faculty of Medicine at the University of Manitoba. Can J Physiol Pharmacol 2009; 87:773-88. [DOI: 10.1139/y09-081] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Blue-green algae, also known as cyanobacteria, produce a variety of toxins, some of which have been implicated in the pathogenesis of severe and potentially life-threatening diseases in humans. As the growth of cyanobacteria within freshwater lakes increases worldwide, it is important to review our present understanding of their toxicity and potential carcinogenicity to gain insight into how these organisms impact human health. This review addresses each of these topics, with special emphasis given to cyanobacterial hepatotoxins within freshwater environments.
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Affiliation(s)
- M.A. Labine
- Section of Hepatology, Department of Medicine, and Pharmacology and Therapeutics, University of Manitoba, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada
| | - G.Y. Minuk
- Section of Hepatology, Department of Medicine, and Pharmacology and Therapeutics, University of Manitoba, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada
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26
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Oatp-associated uptake and toxicity of microcystins in primary murine whole brain cells. Toxicol Appl Pharmacol 2009; 234:247-55. [DOI: 10.1016/j.taap.2008.10.011] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 10/17/2008] [Accepted: 10/20/2008] [Indexed: 02/08/2023]
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27
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Contardo-Jara V, Pflugmacher S, Wiegand C. Multi-xenobiotic-resistance a possible explanation for the insensitivity of bivalves towards cyanobacterial toxins. Toxicon 2008; 52:936-43. [DOI: 10.1016/j.toxicon.2008.09.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 09/12/2008] [Accepted: 09/19/2008] [Indexed: 10/21/2022]
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28
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In vivo influence of cyanobacterial toxins on enzyme activity and gene expression of protein phosphatases in Alfalfa (Medicago sativa). Toxicon 2008; 52:84-90. [PMID: 18620722 DOI: 10.1016/j.toxicon.2008.04.172] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 04/11/2008] [Accepted: 04/14/2008] [Indexed: 11/20/2022]
Abstract
Irrigation of crop plants with surface water can be a threat if cyanobacterial toxins are present in the water. Cyanotoxins are known to cause adverse effects in plants. Microcystin (MC), a cyclic heptapeptide, with more than 70 structural variants, is a frequently occurring toxin. MC is a specific inhibitor of serine/threonine protein phosphatases 1 and 2A (PP1 and 2A), important regulatory enzymes in eukaryotic cells. Protein phosphatases consist of a catalytic subunit and one or more regulatory subunits. In Alfalfa several isoforms of the catalytic subunit of PP1 (MsPP1alpha, MsPP1beta, MsPP1gamma, MsPP1delta, MsPP1varepsilon) and PP2A (MsPP2A Calpha/beta/gamma) are known along with isoforms of the regulatory subunits of PP2A (MsPP2A Aalpha/beta, MsPP2A Balpha/beta). The in vivo effect of environmentally relevant concentrations of cyanobacterial components on the mRNA transcript level of the subunits of protein phosphatases 1 and 2A in Alfalfa (Medicago sativa) was examined using semi-quantitative RT-PCR. Plants were exposed for one week to 5 microg L(-1) microcystin-LR, microcystin-LW, okadaic acid and to cell-free cyanobacterial crude extracts from Microcystis aeruginosa containing 5 microg L(-1) microcystin-LR and a toxin-free crude extract from Synechocystis spp. The protein phosphatase activity in vivo was inhibited when exposed to toxins and crude extract containing microcystin-LR, no change was induced by Synechocystis crude extract. The gene expression of the MsPP1gamma subunit and the MsPP1varepsilon subunit was induced in plants exposed to MC-LW.
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Xie L, Yokoyama A, Nakamura K, Park H. Accumulation of microcystins in various organs of the freshwater snail Sinotaia histrica and three fishes in a temperate lake, the eutrophic Lake Suwa, Japan. Toxicon 2006; 49:646-52. [PMID: 17187838 DOI: 10.1016/j.toxicon.2006.11.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 11/02/2006] [Accepted: 11/09/2006] [Indexed: 10/23/2022]
Abstract
So far, there has been only one study to examine microcystin (MC) contents in various organs of snails in a subtropical Chinese lake. In this study, tissue distribution and seasonal dynamics of MC-RR and -LR were investigated in various organs of a freshwater snail (Sinotaia histrica) in a temperate eutrophic lake, Lake Suwa, Japan. Accumulation of microcystins in some fish was also investigated. There was marked temporal variation in the MC content of various organs of the snail. The digestive tract had the highest MC content (mean 9.03 microg g(-1) DW and range 3.74-23.2 microg g(-1) DW), followed by the gonad (mean 6.90 microg g(-1) DW and range 0.07-22.7 microg g(-1) DW) and hepatopancreas (mean 5.38 microg g(-1) DW and range 1.08-8.79 microg g(-1) DW), whereas the foot had the least (mean 2.48 microg g(-1) DW and range 0.04-4.45 microg g(-1) DW). The disappearance of MC-LR in the hepatopancreas indicated that S. histrica is able to depurate MC-LR efficiently. MC-RR was detected in the muscle of three species of fish, with the highest content in Carassius auratus (79.4 microg kg(-1) BW). Because of substantial MC accumulation in these edible aquatic animals in Lake Suwa, it is recommended that regular monitoring of MCs should be undertaken in both cyanobacteria and aquatic animals.
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Affiliation(s)
- Liqiang Xie
- Department of Environmental Sciences, Faculty of Science, Shinshu University, Matsumoto 390-8621, Japan
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30
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Jayaraj R, Lakshmana Rao PV. Protein phosphorylation profile and adduct formation in liver and kidney of microcystin-LR-treated mice. Toxicon 2006; 48:272-7. [PMID: 16860833 DOI: 10.1016/j.toxicon.2006.05.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 05/13/2006] [Accepted: 05/30/2006] [Indexed: 12/27/2022]
Abstract
Microcystins are cyclic peptide toxins implicated in several livestock and human deaths. The toxicity of microcystins has been attributed to the highly specific inhibition of serine/theronine protein phosphatases-1 and 2A. Reversible protein phosphorylation is an essential regulatory mechanism in many cellular processes. We aimed to investigate the protein phosphatase inhibition, profile of phosphorylated proteins of serine and threonine residues and microcystin-protein phosphatase adduct in vivo after microcystin-LR exposure by intraperitoneal route in mice. At 1 LD(50), there was significant inhibition of protein phosphatases 1 and 2A activity in liver after 30-120 min exposure but there was no effect in kidney. At 0.5 LD(50) there was no inhibition of protein phosphatase activity in both liver and kidney. Similarly, time-dependent phosphorylation of serine and threonine residues was observed at 1 LD(50). Microcystin-LR-protein phosphatase adduct was time and dose dependent in liver. At 0.5 LD(50) the adduct could be detected at 1 and 3 days post-exposure. No adduct could be detected in kidney.
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Affiliation(s)
- R Jayaraj
- Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Jhansi Road, Gwalior-474002, India
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31
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Selheim F, Herfindal L, Martins R, Vasconcelos V, Døskeland SO. Neuro-apoptogenic and blood platelet targeting toxins in benthic marine cyanobacteria from the Portuguese coast. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2005; 74:294-306. [PMID: 16039729 DOI: 10.1016/j.aquatox.2005.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Revised: 06/07/2005] [Accepted: 06/11/2005] [Indexed: 05/03/2023]
Abstract
Six strains of marine cyanobacteria, of which five benthic, were isolated from an area of the Portuguese coast with no known apparent toxic microbial bloom. Five strains were lethal for mice. Four of them produced lethargy and four lead to bleeding. One of the toxic strains was from a genus (Aphanothece) not previously associated with toxin production. Extracts from four isolates induced SH-SY5Y-neuroblastoma cell apoptosis without affecting the viability of hepatocytes, NRK kidney cells, or fibroblasts. Aqueous extract from four isolates inhibited thrombin-induced blood platelet activation, with decreased P-selectin expression, platelet aggregation and shedding of platelet-derived micro-vesicles. Curiously, platelets treated with organic extracts from two of the cyanobacterial strains formed platelet micro-vesicles, expressed P-selectin on the surface and showed a distinct phosphotyrosine protein pattern, but failed to aggregate. We conclude that low-abundance marine cyanobacteria growing at low rates may be an important source for novel toxins that may be useful to dissect mammalian signalling pathways of apoptosis and platelet function.
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Affiliation(s)
- Frode Selheim
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway
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Zurawell RW, Chen H, Burke JM, Prepas EE. Hepatotoxic cyanobacteria: a review of the biological importance of microcystins in freshwater environments. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2005; 8:1-37. [PMID: 15762553 DOI: 10.1080/10937400590889412] [Citation(s) in RCA: 303] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Cyanobacteria possess many adaptations to develop population maxima or "blooms" in lakes and reservoirs. A potential consequence of freshwater blooms of many cyanobacterial species is the production of potent toxins, including the cyclic hepatotoxins, microcystins (MCs). Approximately 70 MC variants have been isolated. Their toxicity to humans and other animals is well studied, because of public health concerns. This review focuses instead on the production and degradation of MCs in freshwater environments and their effects on aquatic organisms. Genetic research has revealed the existence of MC-related genes, yet the expression of these genes seems to be regulated by complex mechanisms and is influenced by environmental factors. In natural water bodies, the species composition of cyanobacterial communities and the ratio of toxic to nontoxic species and strains are largely responsible for total toxin production. Cyanobacteria play vital roles in aquatic food webs, yet production, accumulation, and toxicity patterns of MCs within aquatic food webs remain obscure.
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Affiliation(s)
- Ronald W Zurawell
- Department of Biological Sciences, Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada
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Rao PVL, Jayaraj R, Bhaskar ASB. Protective efficacy and the recovery profile of certain chemoprotectants against lethal poisoning by microcystin-LR in mice. Toxicon 2004; 44:723-30. [PMID: 15500848 DOI: 10.1016/j.toxicon.2004.07.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Accepted: 07/06/2004] [Indexed: 12/11/2022]
Abstract
The cyclic peptide toxins microcystins and nodularins are the most common and abundant cyanotoxins present in diverse water systems. They have been the cause of human and animal health hazards and even death. Development of suitable chemoprotectants against microcystin is essential considering the human health importance. In the present study, three agents cyclosporin-A (10mg/kg), rifampin (25mg/kg) and silymarin (400mg/kg) pre-treatment gave 100% protection against lethal dose of microcystin-LR (100 microg/kg). Various biochemical parameters were evaluated to study the recovery profile of protected animals at 1, 3, 7 and 14 days post-toxin treatment. There was significant depletion of hepatic glutathione in protected animals compared to control group till 7 days post-treatment but normalised by 14 days. Similarly enhanced hepatic lipid peroxidation, inhibition of protein phosphatase activity was observed till 3-7 days post-treatment in protected animals. Elevated levels of enzymes alanine amino transferase, lactate dehydrogenase and sorbitol dehydrogenase were observed in serum at 1 day post-treatment. All the biochemical variables reached control levels by 14 day post-treatment. Immunoblotting analyses of liver homogenates showed microcystin-protein phosphatase adduct in liver samples of toxin treated as well as antidote-protected animals. The adduct could be seen even after 14 days post-toxin treatment. The study shows that though cyclosporin-A, rifampin and silymarin could offer 100% protection against microcystin-LR induced lethality many of the toxic manifestations are persistent and could not be reversed till 7 days.
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Affiliation(s)
- P V Lakshmana Rao
- Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Jhansi Road, Gwalior 474002, India.
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Majsterek I, Sicinska P, Tarczynska M, Zalewski M, Walter Z. Toxicity of microcystin from cyanobacteria growing in a source of drinking water. Comp Biochem Physiol C Toxicol Pharmacol 2004; 139:175-9. [PMID: 15556080 DOI: 10.1016/j.cca.2004.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Revised: 10/13/2004] [Accepted: 10/14/2004] [Indexed: 01/25/2023]
Abstract
Microcystin-LR (MC-LR) is a cyanobacterial heptapeptide that presents acute and chronic hazards to animal and human health. The morphological changes in mitochondria are the primary effect induced by MC-LR leading to cell death. We investigated the toxicity of cyanobacterial microcystin-containing extract (CEM) on the respiratory complex of mammalian mitochondria from Bos taurus. Cyanobacterial blooms of Microcystis aeruginosa were harvested from Sulejow Reservoir, a source of drinking water in central Poland. The concentration of microcystin-LR (MC-LR(CEM)) in CEM extract was determined by high-performance liquid chromatography (HPLC). Commercially available microcystin-LR (Sigma) was used as a standard (MC-LR(S)); both standard and CEM extract were incubated with mitochondria in different doses and time of exposure. MC-RL(CEM) at 1 nM, maximal acceptable dose of microcystin (WHO) in drinking water, provoked activation of cytochrome c oxidase complex in mitochondria. We suggest that it might be considered as a defensive signal of mitochondria against low concentration of a toxic compound. In contrast 1 iM MC-RL(CME) inhibited the activity of mitochondrial oxidase complex much stronger than the same concentration of standard MC-RL(S) (58% vs. 87% of control activity, P<0.05), and this may cause a similar effect to long-term consumption of water. In conclusion, we affirm that CEM extract is highly toxic, and mitochondria could be used as an indicator of this toxicity in vivo, especially during long-term consumption of water from reservoirs where microcystin is produced.
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Affiliation(s)
- Ireneusz Majsterek
- Department of Molecular Genetics, University of Lodz, 12/16 Banacha, 90-237 Lodz, Poland.
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Mikhailov A, Härmälä-Braskén AS, Hellman J, Meriluoto J, Eriksson JE. Identification of ATP-synthase as a novel intracellular target for microcystin-LR. Chem Biol Interact 2003; 142:223-37. [PMID: 12453662 DOI: 10.1016/s0009-2797(02)00075-3] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Microcystins (MCs) are a group of closely related cyclic heptapeptides produced by a variety of common cyanobacteria. These are potent and highly specific hepatotoxins, the toxicity of which is based upon their inhibition of type-1 (PP1) and type-2A (PP2A) protein phosphatases. Apart from protein phosphatases, it is not known whether these phosphatase-inhibiting peptides could bind any other cellular proteins. We wanted to determine whether any possible unknown MC-adducts could explain the apoptotic effects observed at high concentrations of MCs. The question of other possible cellular proteins binding to MCs is also relevant when these compounds are employed for affinity purification of protein phosphatases. In MC-treated cell lysates, antibodies to MC recognized three protein adducts of 35-37 and 55 kD. By immunochemical and proteomics approaches, these proteins were identified as the catalytic subunits of type-1 and type-2A protein phosphatases and the ATP-synthase beta-subunit. The latter target could be associated with the suggested apoptosis-inducing potential of MCs.
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Affiliation(s)
- Andrey Mikhailov
- Turku Center for Biotechnology, POB 123, FIN-20521 Turku, Finland
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Larsen AKR, Møller MTN, Blankson H, Samari HR, Holden L, Seglen PO. Naringin-sensitive phosphorylation of plectin, a cytoskeletal cross-linking protein, in isolated rat hepatocytes. J Biol Chem 2002; 277:34826-35. [PMID: 12095991 DOI: 10.1074/jbc.m205028200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To identify phosphoproteins that might play a role in naringin-sensitive hepatocellular cytoskeletal disruption and apoptosis induced by algal toxins, hepatocyte extracts were separated by gel electrophoresis and immunostained with a phosphothreonine-directed antibody. Use of dilute (5%) polyacrylamide gels containing 6 m urea allowed the resolution of one very large (approximately 500-kDa) okadaic acid- and naringin-sensitive phosphoprotein, identified by tryptic fingerprinting, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and immunostaining as the cytolinker protein, plectin. The naringin-sensitive phosphorylation induced by okadaic acid and microcystin-LR probably reflected inhibition of a type 2A protein phosphatase, whereas the naringin-resistant phosphorylation induced by calyculin A, tautomycin, and cantharidin probably involved a type 1 phosphatase. Okadaic acid caused a collapse of the plectin-immunostaining bile canalicular sheaths and the general cytoskeletal plectin network into numerous medium-sized plectin aggregates. Inhibitors of protein kinase C, cAMP-dependent protein kinase, or Ca(2+)/calmodulin-dependent kinase II had moderate or no protective effects on plectin network disruption, whereas naringin offered 86% protection. Okadaic acid induced a naringin-sensitive phosphorylation of AMP-activated protein kinase (AMPK), the stress-activated protein kinases SEK1 and JNK, and S6 kinase. The AMPK-activating kinase (AMPKK) is likely to be the target of inhibition by naringin, the other kinases serving as downstream components of an AMPKK-initiated signaling pathway.
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Affiliation(s)
- Ann-Kristin Ruud Larsen
- Proteomics and Mammalian Cell Biology Section, Department of Cell Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, 0310 Oslo, Norway
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Yu FY, Liu BH, Chou HN, Chu FS. Development of a sensitive ELISA for the determination of microcystins in algae. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2002; 50:4176-4182. [PMID: 12105942 DOI: 10.1021/jf0202483] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Polyclonal antibodies for microcystin-leucine-arginine (MCYST-LR) were generated from rabbits after immunizing the animals with MCYST-LR conjugated with gamma-globulin. A competitive direct enzyme-linked immunosorbent assay (cdELISA) and a competitive indirect ELISA (ciELISA) were used for the characterization of the antibodies and for analysis of the toxin in algal cultures and dietary supplements. The concentrations causing 50% inhibition (IC(50)) of binding of MCYST-horseradish peroxidase (MCYST-HRP) to the solid-phase antibodies by MCYST-LR, MCYST-arginine-arginine variant (MCYST-RR), MCYST-tyrosine-arginine variant (MCYST-YR), and nodularin (NODLN) in the cdELISA were found to be 0.10, 0.12, 0.14, and 0.20 ng/mL, respectively. In the presence of algae matrix, the detection limit is less than 10 ppb. The overall analytical recovery of MCYST-LR (25 to 500 ng/g) added to the algal dietary supplements and then extracted with 0.1 M ammonium bicarbonate in the cdELISA was found to be 83.7%. Analysis of MCYSTs in algal cultures and dietary supplements showed that six of eleven cultures produce MCYSTs, and five of the algal cultures were not MCYST producers. Eight of eleven tested commercial algal dietary supplements contained MCYSTs at a level lower than 100 ppb. The presence of MCYST-LR in the Microcystis aeruginosa culture was confirmed by high-performance liquid chromatography.
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Affiliation(s)
- Feng-Yih Yu
- Department of Life Science, Chung Shan Medical University, No. 110, Sec. 1, Chien Kuo N. Road, Taichung, Taiwan.
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38
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Abstract
Aminoalkyl matrices are used in affinity chromatography of amine oxidases and other proteins with affinity for amino groups. Under appropriate circumstances chromatography on aminoalkyl matrices may yield purification factors around 100 to 1000, and they have been used in affinity purification of many members of the amine oxidase family. Other proteins with affinity for aminoalkyl matrices include thiol ester proteins, lactoferrin, and proteins with lysine-binding kringles (plasminogen, plasminogen activator, apolipoprotein A). The affinity of thiol ester proteins for aminoalkyl matrices is abolished after inactivation of the thiol ester group by reaction with low molecular weight amines including ammonia. Due to this, an ammonium sulphate precipitation step should be included in purification schemes for amine oxidases. The affinity of lactoferrin for aminoalkyl matrices stems from an affinity for the repeating amino groups in glycosaminoglycans, and this explains why lactoferrin requires diamines for efficient elution. The affinity of plasminogen for aminoalkyl groups is exploited in a one-step purification from plasma, and is also utilised in purification schemes for angiostatin, an angiogenesis-inhibiting fragment of plasminogen. Apolipoprotein A is homologous to plasminogen, and also has affinity for aminohexyl columns. The common binding motif for these proteins are lysine-binding kringles. Due to the properties of the amino group itself, aminoalkyl matrices will inevitably also function as anion exchangers, and this must be taken into consideration in the choice of conditions for sample loading, column washing and elution of bound proteins. Depending on the length of the alkyl chain, the matrices also have a potential for hydrophobic interactions. This property has been exploited in the purification of several proteins but must be minimized during affinity chromatography of amine oxidases. In conclusion, aminoalkyl matrices are valuable tools for affinity chromatography of several different proteins, and simple variations of sample pretreatment, sample loading, and column washing and elution conditions allow efficient selective purification of proteins with different affinities for the matrices.
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Affiliation(s)
- G Houen
- Department of Research and Development, Division of Biologicals, Statens Serum Institut, Artillerivej 5, DK-2300, Copenhagen, Denmark.
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Mankiewicz J, Tarczynska M, Fladmark KE, Doskeland SO, Walter Z, Zalewski M. Apoptotic effect of cyanobacterial extract on rat hepatocytes and human lymphocytes. ENVIRONMENTAL TOXICOLOGY 2001; 16:225-233. [PMID: 11409194 DOI: 10.1002/tox.1028] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Toxic cyanobacterial blooms are an increasing problem in Poland. The production of cyanobacterial toxins and their presence in drinking and recreational waters represent a growing danger to human and animal health. This is connected with the increase of cyanobacterial biomass caused by excessive eutrophication of the water ecosystem. There is evidence that cyanobacterial hepatotoxins can act as a potent promoter of primary liver cancer. The apoptotic effect of microcystins in Polish cyanobacterial bloom samples on rat hepatocytes and human lymphocytes was observed using light and fluorescence microscopy, flow cytometry, and electrophoretic analysis. The incubation time needed to observe the first morphological apoptotic changes in hepatocytes was approximately 30 min; however, the characteristic biochemical changes in DNA were not observed even after 120 min. In lymphocyte cultures the morphological changes characteristic for apoptosis were observed after 24 h of incubation and a 48-h incubation was found to be optimal for analysis of internucleosomal DNA fragmentation, which is one of the main biochemical hallmarks of programmed cell death. These cells are an easily isolated and inexpensive material for medical diagnostics. Therefore the apoptotic changes, together with the clastogenic effect seen in lymphocyte cultures, are proposed as a future analytical method for these toxins.
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Affiliation(s)
- J Mankiewicz
- Department of Molecular Genetics, University of Lodz, Banacha 12/16, 90-237 Lodz, Poland.
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40
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Kaebernick M, Neilan BA, Börner T, Dittmann E. Light and the transcriptional response of the microcystin biosynthesis gene cluster. Appl Environ Microbiol 2000; 66:3387-92. [PMID: 10919796 PMCID: PMC92160 DOI: 10.1128/aem.66.8.3387-3392.2000] [Citation(s) in RCA: 207] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microcystin, a hepatotoxin known to be the cause of animal and human deaths, is produced by the bloom-forming cyanobacterium Microcystis aeruginosa in freshwater bodies worldwide. The toxin is produced nonribosomally via a multifunctional enzyme complex, consisting of both peptide synthetase and polyketide synthase modules coded for by the mcy gene cluster. The recent identification of the mcy genes in the production of microcystin synthetase for the first time provides an avenue to study the regulation of microcystin production at a genetic level. In this study, M. aeruginosa PCC7806 was grown either under continuous light of various intensities or under low light with subsequent short-term exposure to different light intensities and qualities and various stress factors. RNase protection assays were employed to observe the level of mcyB and mcyD transcription under each condition. Both mcyB and mcyD transcript levels were increased under high light intensities and red light. Blue light and certain artificial stress factors (methylviologen and NaCl) led to reduced transcript amounts. There appeared to be two light thresholds, between dark and low light (16 micromol of photons m(-2) s(-1)), and medium (31 micromol of photons m(-2) s(-1)) and high light (68 micromol of photons m(-2) s(-1)), at which a significant increase in transcription occurred. Our findings show that the effect of light on microcystin synthetase production is due to light quality and is initiated at certain threshold intensities, which are not necessarily reflected by observed intracellular toxin bioactivity.
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Affiliation(s)
- M Kaebernick
- School of Microbiology and Immunology, University of New South Wales, Sydney, Australia
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41
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Toivola D, Eriksson J. Toxins Affecting Cell Signalling and Alteration of Cytoskeletal Structure. Toxicol In Vitro 1999; 13:521-30. [DOI: 10.1016/s0887-2333(99)00024-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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42
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Sirén H, Jussila M, Liu H, Peltoniemi S, Sivonen K, Riekkola ML. Separation, purity testing and identification of cyanobacterial hepatotoxins with capillary electrophoresis and electrospray mass spectrometry. J Chromatogr A 1999. [DOI: 10.1016/s0021-9673(99)00105-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Protein phosphatases are responsible for keeping the signaling output of stimulus-activated protein kinases in check; but protein phosphatases are also themselves targets and conveyors of biological signals. Among the major serine/threonine phosphatases, protein phosphatase 2A (PP2A) appears to play a privileged role in the regulation of cell growth and division. How PP2A is regulated is an intriguing question. This review will focus on the role of local protein-protein interactions in PP2A control. Work from a number of laboratories has shown that the catalytic activity, substrate specificity, and subcellular targeting of PP2A are regulated by a remarkably diverse range of regulatory subunits and enzyme inhibitors. On the pathological side, DNA tumor viruses subvert PP2A function by producing proteins that compete with specific regulatory subunits. By interfering with PP2A, these viral proteins can elicit changes in the activity of specific signal transduction pathways, such as the mitogen-activated protein kinase cascade. Recent data indicate that besides classical holoenzyme forms, a fraction of PP2A molecules are associated with novel partners implicated in signal transduction. PP2A biochemically and genetically interacts with the Tap42/alpha4 protein, which is part of a rapamycin-sensitive pathway that connects extracellular stimuli to the initiation of mRNA translation. PP2A also binds to CK2alpha, the catalytic subunit of CK2 (formerly casein kinase 2), and binding is sensitive to mitogenic signaling. The potent effect of quantitatively minor PP2A partners might be explained by a general requirement for docking interactions with substrates under intracellular conditions.
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Affiliation(s)
- Y Goldberg
- INSERM U244, Biochimie des Regulations Cellulaires Endocrines, Departement de Biologie Moleculaire et Structurale, Commissariat a l'Energie Atomique, CEA/Grenoble, France.
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44
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Baysal BE, Farr JE, Goss JR, Devlin B, Richard CW. Genomic organization and precise physical location of protein phosphatase 2A regulatory subunit A beta isoform gene on chromosome band 11q23. Gene X 1998; 217:107-16. [PMID: 9795170 DOI: 10.1016/s0378-1119(98)00350-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Protein phosphatase 2A (PP2A) holoenzyme plays a critical role in cell-cycle control and growth-factor signaling, and is implicated in tumorigenesis. Because the protein phosphatase 2 regulatory subunit A beta isoform gene (PPP2R1B) maps within the critical region of hereditary paraganglioma (PGL1) on chromosomal band 11q23, we characterized its genomic structure and evaluated it as a candidate gene for PGL1. PPP2R1B has 15 exons spanning approx. 27kb genomic distance. We placed the exons on genomic EcoRI fragments and identified their flanking intronic sequences. The gene was oriented from telomere to centromere. Splice acceptor and donor sites of all introns conformed to the GT/AG rule. Northern analysis with a cDNA probe identified 2.5kb and 5.0kb transcript sizes. We identified an ATG initiation codon in a favorable context and mapped two transcription start sites 15bp and 66bp upstream of it. We also mapped a 3'-polyadenylation site 504bp downstream of the TGA stop codon, consistent with the 2.5kb transcript size. We did not detect germ-line mutations by single-stranded conformational polymorphism (SSCP) analysis or major rearrangements by Southern analysis in a set of PGL1 patients. In conclusion, we precisely mapped and characterized the structure of PPP2R1B and evaluated it as a candidate gene for PGL1.
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Affiliation(s)
- B E Baysal
- Department of Psychiatry, The University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA. baysalbe+@pitt.edu
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45
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Williams DE, Dawe SC, Kent ML, Andersen RJ, Craig M, Holmes CF. Bioaccumulation and clearance of microcystins from salt water mussels, Mytilus edulis, and in vivo evidence for covalently bound microcystins in mussel tissues. Toxicon 1997; 35:1617-25. [PMID: 9428108 DOI: 10.1016/s0041-0101(97)00039-1] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Over a period of 3 days saltwater mussels, Mytilus edulis, were fed a cyanobacteria, Microcystis aeruginosa, that contained a high concentration of microcystins. The mussels were killed on a periodic basis over the course of 2 months. Mussels were also collected at two sites were high levels of microcystins in tissues had been noted. A strategy based on the chemically unique nature of the C20 beta-amino acid, (2S,3S,8S,9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6- dienoic acid (Adda), portion of the microcystins was used in conjunction with a protein phosphatase (PPase) assay to analyse for both covalently bound microcystins and free microcystins in the mussel tissues. The mussel PPase assay results were compared with the Lemieux oxidation gas chromatography-mass spectrometry (GCMS) analysis. Less than 0.1% of the total microcystin burden in the mussel tissue was found to be extractable with MeOH. Thus, direct evidence was provided for the existence of covalently bound microcystins in mussel tissues in vivo. The mussels rapidly cleared the covalently bound microcystins when transferred to untreated seawater. Within 4 days the total microcystin burden dropped from a high of 336.9 (+/- 45.8) micrograms/g wet tissue to 11.3 (+/- 2.6) micrograms/g. After 4 days postexposure until completion of the experiment the total levels remained below the detection limits of the GCMS method. The levels of free microcystins, extracted with MeOH and detected by the PPase assay, fell from 204 ng/g wet tissue to a residual 14 ng/g over a 53 day postexposure period. Presumably the bound microcystin present in the mussel tissue exists as a covalent complex with the PP-1 and PP-2A enzymes. We conclude that in any shellfish monitoring program it is the total tissue microcystin burden that needs to be considered.
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Affiliation(s)
- D E Williams
- Department of Chemistry and Oceanography, University of British Columbia, Vancouver, Canada
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46
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Gupta V, Ogawa AK, Du X, Houk KN, Armstrong RW. A model for binding of structurally diverse natural product inhibitors of protein phosphatases PP1 and PP2A. J Med Chem 1997; 40:3199-206. [PMID: 9379439 DOI: 10.1021/jm960873x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Protein phosphatases play significant roles in signal transduction pathways pertaining to cell proliferation, gene expression, and neurotransmission. Serine/threonine phosphatases PP1 and PP2A, which are closely related in primary structure (approximately 50%), are inhibited by a structurally diverse group of natural toxins. As part of our study toward understanding the mechanism of inhibition displayed by these toxins, we have developed research in two directions: (1) The standardization of an assay to be used in acquisition of the structure--activity relationship of inhibition data is reported. This nonradioactive assay affords detection levels of molecular phosphate released from a phosphorylated hexapeptide in subnanomolar quantities. The comparison of our IC50 values of these inhibitors against corresponding literature data provided validation for our method. (2) Computational analysis provided a global model for binding of these inhibitors to PP1. The natural toxins were shown to possess remarkably similar three-dimensional motifs upon superimposition and van der Waals minimization within the PP1 active site.
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Affiliation(s)
- V Gupta
- Department of Chemistry and Biochemistry, University of California, Los Angeles 90095, USA
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47
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Williams DE, Craig M, Dawe SC, Kent ML, Andersen RJ, Holmes CF. 14C-labeled microcystin-LR administered to Atlantic salmon via intraperitoneal injection provides in vivo evidence for covalent binding of microcystin-LR in salmon livers. Toxicon 1997; 35:985-9. [PMID: 9241792 DOI: 10.1016/s0041-0101(96)00196-1] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The tissue distribution and clearance of radiolabeled microcystin-LR administered to Atlantic salmon via i.p. injection has been re-examined using uniformly 14C-labeled toxin. Significant differences were found to exist between these results and those obtained when fish received an i.p. injection of tritium-labeled dihydromicrocystin-LR. In addition, MeOH liver extracts were assayed by both phosphatase assay and 14C counts and the results compared with the total levels of incorporation determined by digestion and subsequent 14C counting of the same live tissues. An attempt to investigate the metabolism and to document the putative products was also undertaken. It was found that microcystin-LR was extensively metabolized to compounds that are more polar than the parent compound.
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Affiliation(s)
- D E Williams
- Department of Chemistry, University of British Columbia, Vancouver, Canada
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48
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Williams DE, Craig M, McCready TL, Dawe SC, Kent ML, Holmes CF, Andersen RJ. Evidence for a covalently bound form of microcystin-LR in salmon liver and Dungeness crab larvae. Chem Res Toxicol 1997; 10:463-9. [PMID: 9114985 DOI: 10.1021/tx9601519] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The chemically unique nature of the C20 beta-amino acid (2S,3S,8S,9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6- dienoic acid (Adda) portion of the microcystins has been exploited to develop a strategy to analyze for the total microcystin-LR (1; see Figure 1) burden in salmon liver and crab larvae tissues. Lemieux oxidation of microcystin-LR (1) gives 2-methyl-3-methoxy-4-phenylbutanoic acid (2), a unique marker for the presence of microcystins. The butanoic acid 2 can be isolated and detected by GC/MS from the livers of Atlantic salmon that received an ip injection of microcystin-LR (1) and from tissues of wild-caught crab larvae. The Lemieux oxidation-GC/MS results are compared with those from MeOH extraction-PPase analysis. Only approximately 24% of the total microcystin-LR (1) burden in salmon liver tissue is found to be extractable with MeOH. Similarly, the Lemieux oxidation-GC/MS method detected 10,000-fold greater microcystin concentrations in Cypress Island Dungeness crab larvae than did the MeOH extraction-PPase method. The disparity in microcystin concentrations measured by the two methods is taken as direct evidence for the existence of covalently bound microcystins in vivo.
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Affiliation(s)
- D E Williams
- Department of Chemistry, University of British Columbia, Vancouver, Canada
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49
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Tencalla F, Dietrich D. Biochemical characterization of microcystin toxicity in rainbow trout (Oncorhynchus mykiss). Toxicon 1997; 35:583-95. [PMID: 9133713 DOI: 10.1016/s0041-0101(96)00153-5] [Citation(s) in RCA: 129] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The kinetics and biochemical effects of microcystins in rainbow trout were studied with freeze-dried toxic cells of Microcystis aeruginosa, strain PCC 7806. Following in vivo exposure the changes in liver histology were observed over a 72 hr period and the absorption of microcystins from the gastrointestinal tract into the blood and liver, as well as the inhibition of hepatic protein phosphatase 1 and 2A activities, were recorded using the protein phosphatase inhibition assay. The interaction between microcystins and trout liver phosphatases was further tested in vitro using the protein phosphatase inhibition assay. The in vivo experiments demonstrated a high organotropy of microcystins for the liver, where rapid and total inhibition of protein phosphatase 1 and 2A activity was observed. Maximal inhibition of phosphatases was observed 3 hr after gavage. At that time-point, approximately 63% of the toxin present in the liver was refractive to detection via the phosphatase inhibition assay and therefore most likely covalently bound to cellular proteins. The inhibition of hepatic protein phosphatases 1 and 2A proved to be transient only, as a progressive increase in phosphatase activity was observed beginning 12 hr after gavage of the fish, reaching approximately 50% of the control activity at 72 hr. In contrast, liver damage continued to progress despite this renewed protein phosphatase activity.
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Affiliation(s)
- F Tencalla
- Institute of Toxicology, Federal Institute of Technology, Schwerzenbach, Switzerland
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50
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Toivola DM, Goldman RD, Garrod DR, Eriksson JE. Protein phosphatases maintain the organization and structural interactions of hepatic keratin intermediate filaments. J Cell Sci 1997; 110 ( Pt 1):23-33. [PMID: 9010781 DOI: 10.1242/jcs.110.1.23] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The importance of protein phosphatases in the maintenance of cytoskeletal structure is supported by the serious liver injury caused by microcystin-LR, a hepatotoxic inhibitor of type-1 and type-2A serine/threonine protein phosphatases. We used the microcystin-LR-induced cell injury as a model to study the roles of protein dephosphorylation in maintaining cytoskeletal structure and cellular interactions in primary rat hepatocyte cultures. Confocal microscopy revealed that the first visible effect of microcystin-LR is disruption of desmoplakin organization at the cell surface, indicating dissociation of desmosomes. This effect is followed by a dramatic reorganization of both the intermediate filament (keratins 8 and 18) and microfilament networks, resulting in a merged structure in which the intermediate filaments are organized around a condensed actin core. Keratin 8, keratin 18 and desmoplakin I/II are the major cytoskeleton-associated targets for microcystin-LR-induced phosphorylation. Hyperphosphorylation of keratin 8 and 18 is accompanied by an increased keratin solubility, which correlates with the observed morphological effects. Phosphopeptide mapping shows that four specific tryptic phosphopeptides are highly phosphorylated predominantly in the soluble pool of keratin 18, whereas keratin 8 shows no indications of such assembly state-specific sites. Phosphopeptide maps of keratins phosphorylated in vivo and in vitro indicate that Ca2+/calmodulin-dependent kinase may be involved in regulating the serine-specific phosphorylation of both keratin 8 and keratin 18, while cAMP-dependent protein kinase does not seem to play a major role in this context. Taken together, our results show that the interactions between keratin intermediate filaments and desmosomes as well as the assembly states of their main constituent proteins, are directly regulated by serine/threonine kinase/phosphatase equilibria.
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Affiliation(s)
- D M Toivola
- Department of Biology, Abo Akademi University, Turku, Finland
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