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Feurstein D, Kleinteich J, Heussner AH, Stemmer K, Dietrich DR. Investigation of microcystin congener-dependent uptake into primary murine neurons. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:1370-5. [PMID: 20472527 PMCID: PMC2957914 DOI: 10.1289/ehp.0901289] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Accepted: 05/15/2010] [Indexed: 05/16/2023]
Abstract
BACKGROUND Contamination of natural waters by toxic cyanobacteria is a growing problem worldwide, resulting in serious water pollution and human health hazards. Microcystins (MCs) represent a group of > 80 cyclic heptapeptides, mediating cytotoxicity via specific protein phosphatase (PP) inhibition at equimolar concentrations (comparable toxicodynamics). Because of the structure and size of MCs, active uptake into cells occurs via organic anion-transporting polypeptides (OATP/Oatp), as confirmed for liver-specific human OATP1B1 and OATP1B3, mouse Oatp1b2 (mOatp1b2), skate Oatp1d1, and the more widely distributed OATP1A2 expressed, for example, at the blood-brain barrier. Tissue-specific and cell-type-specific expression of OATP/Oatp transporters and specific transport of MC congeners (toxicokinetics) therefore appear prerequisite for the reported toxic effects in humans and other species upon MC exposure. Beyond hepatotoxicity induced by the MC-LR congener, the effects of other MC congeners, especially neuronal uptake and toxicity, are unknown. OBJECTIVES In this study we examined the expression of mOatps and the uptake of congeners MC-LR, MC-LW, and MC-LF in primary murine neurons. METHODS Intracellular MC accumulation was indicated indirectly via uptake inhibition experiments and directly confirmed by Western blot analysis and a PP inhibition assay. Neuronal mOatp expression was verified at the mRNA and protein level. RESULTS MCs can cross neuronal cell membranes, with a subsequent decrease of PP activity. Of 15 mOatps, 12 were expressed at the mRNA level, but we found detectable protein levels for only two: mOatp1a5 (Slco1a5) and the known MC-LR transporter mOatp1b2 (Slco1b2). CONCLUSIONS These data suggest mOatp-mediated uptake of MC congeners into neurons, thus corroborating earlier assumptions of the neurotoxic potential of MCs.
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Affiliation(s)
- Daniel Feurstein
- Human and Environmental Toxicology, University of Konstanz, Konstanz, Germany.
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2
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Sicińska P, Bukowska B, Michałowicz J, Duda W. Damage of cell membrane and antioxidative system in human erythrocytes incubated with microcystin-LR in vitro. Toxicon 2006; 47:387-97. [PMID: 16457864 DOI: 10.1016/j.toxicon.2005.12.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Revised: 11/28/2005] [Accepted: 12/06/2005] [Indexed: 11/28/2022]
Abstract
The effect of the exposure of human erythrocytes to different concentrations of microcystin-LR were studied. Lipid peroxidation, membrane fluidity, cell morphology, haemoglobin oxidation and changes in the activity of antioxidant enzymes were investigated. Human erythrocytes were incubated with microcystin-LR at concentrations of 1-1000 nM for 1, 6, 12 and 24 h. We observed that microcystin-LR induces a significant increase of the level of thiobarbituric acid reactive substances (TBARS), formation of echinocytes, haemolysis, conversion of oxyhaemoglobin to methaemoglobin, decrease of membrane fluidity on the level of 16 carbon atom fat acids. The compound also changed antioxidative enzymes activities: catalase, superoxide dismutase and glutathione reductase and formation of reactive oxygen species (ROS). All of the observed changes point out that 100 nM of Microcistin LR is the liminal (threshold) toxic dose for human erythrocytes. This dose caused most of the described changes. Observed damages of erythrocytes membrane and antioxidative enzymes may be the result of direct covalent binding of microcystin-LR with -SH residues of proteins and indirectly be related with reactive oxygen species formation.
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Affiliation(s)
- Paulina Sicińska
- Department of Biophysics Environmental Pollution, University of Łódź, Banacha 12/16, 90-237 Łódź, Poland
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3
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Chong MW, Gu KD, Lam PK, Yang M, Fong WF. Study on the cytotoxicity of microcystin-LR on cultured cells. CHEMOSPHERE 2000; 41:143-147. [PMID: 10819192 DOI: 10.1016/s0045-6535(99)00402-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The toxicity of purified blue-green algal toxin, microcystin-LR, on permanent cell lines KB, NIH/3T3, H-4-II-E, HeLa, Vero, Hep G2, Caco-2 and HL-60 was studied. Assessment of cell viability using colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays indicated that purified microcystin-LR induced toxic effect on KB and H-4-II-E cell lines after 96 h incubation at toxin concentrations greater than 18.75 microg/ml. KB cell line was selected for further study when reproducibility, consistency and sensitivity were considered. Significant amounts of lactate dehydrogenase (LDH) were released from KB cells when incubation durations were 72 and 96 h with toxin concentrations of 18.75 microg/ml and higher. Although previous studies suggested that microcystin-LR had no cytotoxic effect on permanent cell lines, LDH release assay performed on KB cells indicated that exposure to microcystin-LR could result in damage to the cell membrane.
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Affiliation(s)
- M W Chong
- Department of Biology and Chemistry, Centre for Environmental Science, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, People's Republic of China
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Takahashi O, Oishi S, Watanabe MF. Defective blood coagulation is not causative of hepatic haemorrhage induced by microcystin-LR. PHARMACOLOGY & TOXICOLOGY 1995; 76:250-4. [PMID: 7617554 DOI: 10.1111/j.1600-0773.1995.tb00138.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Male rats were intraperitoneally administered a lethal dose of microcystin-LR (a toxin of cyanobacteria). Prior to haemorrhage in the liver, blood coagulation and platelet aggregation activities were measured. The number of cellular components, white blood cells, red blood cells and, especially, platelets, decreased 1-1.5 hr after the injection. Plasma kaolin-activated partial thromboplastin time was prolonged and fibrinogen concentration was reduced, but antithrombin III activity and fibrin degradation product concentration were not significantly changed. Platelet aggregation was not affected for up to 0.5-1.0 hr after administration. Sequential analyses of those parameters and hepatotoxic markers indicate that those hematologic changes as well as the hepatic injury occur suddenly after the massive bleeding. These results suggest that microcystin-LR does not directly act on the haemostatic system to cause a disseminated intravascular coagulation-like state. The decrease in blood coagulation activity and platelet particle concentration may be the results of secondary consumptive effects following the hepatic haemorrhage.
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Affiliation(s)
- O Takahashi
- Department of Toxicology, Tokyo Metropolitan Research Laboratory of Public Health, Japan
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6
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Nagata S, Soutome H, Tsutsumi T, Hasegawa A, Sekijima M, Sugamata M, Harada K, Suganuma M, Ueno Y. Novel monoclonal antibodies against microcystin and their protective activity for hepatotoxicity. NATURAL TOXINS 1995; 3:78-86. [PMID: 7613739 DOI: 10.1002/nt.2620030204] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Six monoclonal antibodies (MAbs) to microcystin-LR (MCLR), a cyclic heptapeptide hepatotoxin isolated from the cyanobacterium Microcystis aeruginosa, were produced. They showed the protective effects on hepatotoxicity of MCLR in vitro and in vivo, and on the inhibition of protein phosphatase by MCLR. Competitive enzyme-linked immunosorbent assays with various microcystins revealed that the six MAbs recognized a part of the molecule, in particular, a tertial structure around Adda, 3-amino-9-methoxy-2,6,8,-trimethyl-10-phenyldeca-4,6-dienoic acid. The specificity of these MAbs varied slightly. In primary rat hepatocyte cultures, all MAbs showed protective effects against the MCLR-induced cell damages, assessed by morphological changes, lactate dehydrogenase release into the medium, and a calorimetric assay to measure the cell viability using a tetrazolium dye. The M8H5 MAb showing the highest affinity for MCLR blocked the lethal effects and hepatocellular damage to mice. In addition, M8H5 MAb recovered protein phosphatase 2A inhibition by MCLR in a dose-dependent manner, while phosphatase inhibition by okadaic acid was not affected. Thus, the MAbs specifically reacted with the microcystins and prevented their biological activities. This is the first report on the protective effects of specific monoclonal antibodies on MCLR-induced toxicity.
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MESH Headings
- Animals
- Antibodies, Monoclonal/biosynthesis
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/metabolism
- Antibody Specificity
- Binding, Competitive
- Calorimetry
- Cell Survival/drug effects
- Cells, Cultured
- Cyanobacteria/immunology
- Cyanobacteria/metabolism
- Dose-Response Relationship, Drug
- Enzyme-Linked Immunosorbent Assay
- Female
- Hybridomas
- In Vitro Techniques
- L-Lactate Dehydrogenase/metabolism
- Liver/cytology
- Liver/drug effects
- Liver/pathology
- Male
- Mice
- Mice, Inbred BALB C
- Microcystins
- Peptides, Cyclic/chemistry
- Peptides, Cyclic/immunology
- Peptides, Cyclic/toxicity
- Phosphoprotein Phosphatases/antagonists & inhibitors
- Protein Phosphatase 2
- Rats
- Rats, Inbred F344
- Structure-Activity Relationship
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Affiliation(s)
- S Nagata
- Department of Toxicology and Microbial Chemistry, Faculty of Pharmaceutical Sciences, Science University of Tokyo, Japan
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7
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Toivola DM, Eriksson JE, Brautigan DL. Identification of protein phosphatase 2A as the primary target for microcystin-LR in rat liver homogenates. FEBS Lett 1994; 344:175-80. [PMID: 8187879 DOI: 10.1016/0014-5793(94)00382-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The liver-specific toxin microcystin-LR (MC-LR) is a potent inhibitor of type 1 (PP1) and type 2A (PP2A) protein phosphatases. A tritiated form of the toxin, [3H]dihydromicrocystin-LR ([3H]DMC-LR), was used to identify target proteins in cellular fractions prepared from rat liver homogenates. About 80% of the [3H]DMC-LR bound to proteins was in the cytosolic fraction, which contained essentially all of the PP2A. In contrast, much of the PP1 was found in particulate fractions, each with only a few percent of the total protein-bound [3]HDMC-LR. Protein-bound [3H]DMC-LR in the cytosol co-eluted with PP2A, but not with PP-1 from a DEAE-Sepharose column. Native forms of liver cytoplasmic PP2A and PP1 separated by aminohexyl-Sepharose adsorption showed similar sensitivity to inhibition by MC-LR, and bound [3H]DMC-LR proportional to the amount of phosphatase activity. The results indicate that [3H]DMC-LR can bind both PP2A and PP1 in the liver which must be important for microcystin-induced toxicity, but is recovered mainly bound to PP2A in the cytosol.
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Affiliation(s)
- D M Toivola
- Department of Biology, Abo Akademi University, Turku, Finland
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8
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Macías-Silva M, García-Sáinz JA. Inhibition of hormone-stimulated inositol phosphate production and disruption of cytoskeletal structure. Effects of okadaic acid, microcystin, chlorpromazine, W7 and nystatin. Toxicon 1994; 32:105-12. [PMID: 9237342 DOI: 10.1016/0041-0101(94)90026-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Inhibition of protein phosphatases 2A and 1 by okadaic acid and microcystin leads to cytoskeletal disruption and formation of plasma membrane blebs (blebbing) in hepatocytes. This phenomenon is associated to a marked inhibition of receptor-mediated and G-protein-mediated phosphoinositide turnover in rat hepatocytes. Other cytoskeletal-disrupting drugs such as chlorpromazine, W7 and nystatin mimic the effect of these protein phosphatase inhibitors on phosphoinositide metabolism and blebbing. Our data suggest that the coupling between G-protein and phospholipase C might be altered by cytoskeletal disruption.
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Affiliation(s)
- M Macías-Silva
- Instituto de Fisiología Cellular, Universidad Nacional Autónoma de México, Méico, D.F
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9
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Henning K, Meyer H, Kraatz-Wadsack G, Cremer J. Detection of a cytotoxic substance produced by the cyanobacteriumMicrocystis aeruginosa strain PCC 7806: Isolation and differentiation from the peptide toxin microcystin-LR by cytotoxicity assays. Curr Microbiol 1992. [DOI: 10.1007/bf01571020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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10
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Sepulveda MS, Rojas M, Zambrano F. Inhibitory effect of a Microcystis sp (cyanobacteria) toxin on development of preimplantation mouse embryos. ACTA ACUST UNITED AC 1992; 102:549-53. [PMID: 1360361 DOI: 10.1016/0742-8413(92)90157-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
1. A soluble toxin, purified from the algae bloom of an eutrophic lake dominated by Microcystis, is a very effective inhibitor of early embryo development in a dose-response relationship. 2. Two- and 8-cell mouse embryos under the influence of Microcystis toxin do not reach the developmental stages of morula and blastocyst, respectively. 3. Actin cortex is disorganized without change in the microtubules structure. 4. Results are discussed in terms of the possible mechanisms by which the toxin arrests development considering, specifically, effects on the cytoskeleton and/or on voltage-insensitive transmembrane Ca2+ channels.
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Affiliation(s)
- M S Sepulveda
- Departamento de Biologia, Facultad de Ciencias, Universidad de Chile
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11
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Henning K, Cremer J, Meyer H. Cytotoxicity of cyanobacterium Microcystis aeruginosa. ZENTRALBLATT FUR VETERINARMEDIZIN. REIHE B. JOURNAL OF VETERINARY MEDICINE. SERIES B 1992; 39:307-10. [PMID: 1519410 DOI: 10.1111/j.1439-0450.1992.tb01174.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cytotoxic effects of crude extracts and fractions of the purification steps towards Microcystin-LR (MCYST-LR) were investigated in vitro. Cytotoxicity was evaluated by measure of lactate dehydrogenase liberation of Chang liver cells and by hemolysis. Crude extracts of strain PCC 7806 damaged the cells within a few minutes. In contrast, MCYST-LR did not show any detectable cytotoxic effects. The cytotoxic activity could be related to a heat-labile substance with a molecular weight of about 30,000 Da.
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Affiliation(s)
- K Henning
- Institute of Microbiology, Federal Armed Forces, Medical Academy, Munich
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12
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Runnegar MT, Gerdes RG, Falconer IR. The uptake of the cyanobacterial hepatotoxin microcystin by isolated rat hepatocytes. Toxicon 1991; 29:43-51. [PMID: 1903001 DOI: 10.1016/0041-0101(91)90038-s] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Microcystin-YM a cyclic heptapeptide hepatotoxin isolated from the cyanobacterium Microcystis aeruginosa was radiolabeled with 125I, and used to investigate the uptake of the toxin by freshly isolated rat hepatocytes. The uptake was temperature dependent with apparent activation energy of 18 kcal/mole (77 kJ/mole) for the initial rate of uptake. Uptake of non-toxic (10-20 nM) doses of microcystin by hepatocytes continued with time, the intracellular to extracellular distribution ratio for the toxin was 70 at 60 min for 10(6) cells/ml. Uptake of higher doses of microcystin (100 nM and more) stopped when the cells blebbed: a toxic response of hepatocytes to microcystin. Uptake of microcystin by hepatocytes was inhibited 70-80% by the addition of 10 microM sodium deoxycholate or bromsulphthlein, compounds that protect hepatocytes from the toxic effects of microcystin.
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Affiliation(s)
- M T Runnegar
- Department of Biochemistry, Microbiology, and Nutrition, University of New England, Armidale, NSW, Australia
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13
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Eriksson JE, Toivola D, Meriluoto JA, Karaki H, Han YG, Hartshorne D. Hepatocyte deformation induced by cyanobacterial toxins reflects inhibition of protein phosphatases. Biochem Biophys Res Commun 1990; 173:1347-53. [PMID: 2176489 DOI: 10.1016/s0006-291x(05)80936-2] [Citation(s) in RCA: 215] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The cyclic peptide hepatotoxins microcystin-LR, 7-desmethyl-microcystin-RR and nodularin are potent inhibitors of the protein phosphatases type 1 and type 2A. Their potency of inhibition resembles calyculin-A and to a lesser extent okadaic acid. These hepatotoxins increase the overall level of protein phosphorylation in hepatocytes. Evidence is presented to indicate that in hepatocytes the morphological changes and effects on the cytoskeleton are due to phosphatase inhibition. The potency of these compounds in inducing hepatocyte deformation is similar to their potency in inhibiting phosphatase activity. These results suggest that the hepatotoxicity of these peptides is related to inhibition of phosphatases, and further indicate the importance of the protein phosphorylation in maintenance of structural and homeostatic integrity in these cells.
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Affiliation(s)
- J E Eriksson
- Dept. Biology, Abo Akademi Univ., Turku, Finland
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14
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Ichinose M, Endo S, Critz SD, Shenolikar S, Byrne JH. Microcystin-LR, a potent protein phosphatase inhibitor, prolongs the serotonin- and cAMP-induced currents in sensory neurons of Aplysia californica. Brain Res 1990; 533:137-40. [PMID: 1964827 DOI: 10.1016/0006-8993(90)91806-r] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Microcystin-LR (MCYST-LR), a hepatotoxin produced by cyanobacteria, inhibited purified protein phosphatases (PrPs) from rabbit skeletal muscle and the enzymes from Aplysia with an IC50 of approximately 10(-10) M. MCYST-LR also prolonged both serotonin- (5-HT) and cyclic adenosine monophosphate-induced inward currents in sensory neurons of Aplysia. These results, which are consistent with inhibition of Aplysia PrPs, indicate that MCYST-LR may be a useful probe to elucidate the function of PrPs in neural tissues.
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Affiliation(s)
- M Ichinose
- Department of Neurobiology and Anatomy, University of Texas Medical School, Houston 77225
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15
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Matsushima R, Yoshizawa S, Watanabe MF, Harada K, Furusawa M, Carmichael WW, Fujiki H. In vitro and in vivo effects of protein phosphatase inhibitors, microcystins and nodularin, on mouse skin and fibroblasts. Biochem Biophys Res Commun 1990; 171:867-74. [PMID: 2169738 DOI: 10.1016/0006-291x(90)91226-i] [Citation(s) in RCA: 162] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Three microcystins, YR, LR and RR and nodularin, all of which are hepatotoxic compounds, inhibited dose-dependently the activity of protein phosphatase 2A in and the specific [3H]okadaic acid binding to a cytosolic fraction of mouse skin, as strongly as okadaic acid. However, microcytins and nodularin did not induce any effects on mouse skin or primary human fibroblasts. Microinjection of microcystin YR into primary human fibroblasts induced morphological changes which were induced by incubation with okadaic acid. Microcystins and nodularin penetrate into the epithelial cells of mouse skin and human fibroblasts with difficulty, which reflects tissue specificity of the compounds.
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Affiliation(s)
- R Matsushima
- Cancer Prevention Division, National Cancer Center Research Institute, Tokyo, Japan
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16
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Eriksson JE, Grönberg L, Nygård S, Slotte JP, Meriluoto JA. Hepatocellular uptake of 3H-dihydromicrocystin-LR, a cyclic peptide toxin. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1025:60-6. [PMID: 2369577 DOI: 10.1016/0005-2736(90)90190-y] [Citation(s) in RCA: 136] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The cellular uptake of microcystin-LR, a cyclic heptapeptide hepatotoxin from the cyanobacterium Microcystis aeruginosa, was studied by means of a radiolabelled derivative of the toxin. 3H-dihydromicrocystin-LR. The uptake of 3H-dihydromicrocystin-LR was shown to be specific for freshly isolated rat hepatocytes whereas the uptake in the human hepatocarcinoma cell line Hep G2 as well as the mouse fibroblast cell line NIH-3T3, and the human neuroblastoma cell line SH-SY5Y, was negligible. By means of a surface barostat technique it was shown that the membrane penetrating capacity (surface activity) of microcystin-LR was low, indicating that the toxin requires an active uptake mechanism. The hepatocellular uptake of microcystin-LR could be inhibited in the presence of bile acid transport inhibitors such as antamanide (5 microM), sulfobromophthalein (50 microM) and rifampicin (30 microM). The uptake was also reduced in a concentration dependent manner when the hepatocytes were incubated in the presence the bile salts cholate and taurocholate. A complete inhibition of the hepatocellular uptake was achieved by 100 microM of either bile salt. The overall results indicate that the uptake of microcystin-LR is through the multispecific transport system for bile acids. This mechanism of cell entry would explain the previously observed cell specificity and organotropism of microcystin-LR.
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Affiliation(s)
- J E Eriksson
- Department of Biology, Abo Akademi University, Turku, Finland
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18
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Meriluoto JA, Nygård SE, Dahlem AM, Eriksson JE. Synthesis, organotropism and hepatocellular uptake of two tritium-labeled epimers of dihydromicrocystin-LR, a cyanobacterial peptide toxin analog. Toxicon 1990; 28:1439-46. [PMID: 2128565 DOI: 10.1016/0041-0101(90)90157-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Two tritium-labeled epimers of dihydromicrocystin-LR, a derivative of the cyanobacterial peptide hepatotoxin microcystin-LR, were synthesized by reduction with sodium boro[3H]hydride and purified with reversed-phase liquid chromatography. The epimers were hepatotoxic in mice; the i.p. LD50 was 120-135 micrograms/kg. They were concentrated in the liver and to some extent in the intestine and the kidney after an i.v. injection. Freshly isolated rat hepatocytes showed a rapid uptake of both epimers. The cellular uptake of the epimers was almost complete within 5 min at concentrations 1 microM (0.5 microM dihydromicrocystin-LR + 0.5 microM microcystin-LR) and 4 microM (0.5 microM + 3.5 microM). The uptake of the earlier eluting epimer was about three times higher than that of the later eluting epimer.
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Affiliation(s)
- J A Meriluoto
- Abo Akademi University, Department of Biochemistry and Pharmacy, Turku, Finland
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19
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Rojas M, Nuñez MT, Zambrano F. Inhibitory effect of a toxic peptide isolated from a waterbloom of Microcystis sp. (Cyanobacteria) on iron uptake by rabbit reticulocytes. Toxicon 1990; 28:1325-32. [PMID: 2128422 DOI: 10.1016/0041-0101(90)90097-q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of a soluble toxin purified from the algae bloom of a eutrophic lake dominated by Microcystis on the receptor-mediated endocytosis of ferro-transferrin in rabbit reticulocytes was studied. The toxin was a very effective inhibitor of cell iron uptake. Kinetic studies using 125I, 59Fe-labeled transferrin indicated that the step of ferrotransferrin internalization was selectively inhibited by the toxin while the surface receptor-binding capacity, the externalization of previously internalized transferrin, and the cellular ATP levels were not affected. These findings indicate that the reduction of iron uptake caused by the toxin is due to inhibition of the internalization of surface-located transferrin-transferrin receptor complexes, perhaps due to a disruption of cytoskeleton integrity.
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Affiliation(s)
- M Rojas
- Departamento de Biologia, Facultad de Ciencias, Universidad de Chile
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20
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Eriksson JE, Paatero GI, Meriluoto JA, Codd GA, Kass GE, Nicotera P, Orrenius S. Rapid microfilament reorganization induced in isolated rat hepatocytes by microcystin-LR, a cyclic peptide toxin. Exp Cell Res 1989; 185:86-100. [PMID: 2806414 DOI: 10.1016/0014-4827(89)90039-6] [Citation(s) in RCA: 124] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The cyclic heptapeptide hepatotoxin microcystin-LR from the cyanobacterium Microcystis aeruginosa induces rapid and characteristic deformation of isolated rat hepatocytes. We investigated the mechanism(s) responsible for cell shape changes (blebbing). Our results show that the onset of blebbing was accompanied neither by alteration in intracellular thiol and Ca2+ homeostasis nor by ATP depletion. The irreversible effects were insensitive to protease and phospholipase inhibitors and also to thiol-reducing agents, excluding the involvement of enhanced proteolysis, phospholipid hydrolysis, and thiol modification in microcystin-induced blebbing. In contrast, the cell shape changes were associated with a remarkable reorganization of microfilaments as visualized both by electron microscopy and by fluorescent staining of actin with rhodamine-conjugated phalloidin. The morphological effects and the microfilament reorganization were specific for microcystin-LR and could not be induced by the microfilament-modifying drugs cytochalasin D or phalloidin. Using inhibition of deoxyribonuclease I as an assay for monomeric actin, we found that the microcystin-induced reorganization of hepatocyte microfilaments was not due to actin polymerization. On the basis of the rapid microfilament reorganization and the specificity of the effects, it is suggested that microcystin-LR constitutes a novel microfilament-perturbing drug with features that are clearly different from those of cytochalasin D and phalloidin.
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Affiliation(s)
- J E Eriksson
- Department of Biology, Abo Akademi University, Turku, Finland
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22
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Birk IM, Dierstein R, Kaiser I, Matern U, König WA, Krebber R, Weckesser J. Nontoxic and toxic oligopeptides with D-amino acids and unusual residues in Microcystis aeruginosa PCC 7806. Arch Microbiol 1989; 151:411-5. [PMID: 2500922 DOI: 10.1007/bf00416599] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Toxic and nontoxic peptides were isolated from the cyanobacterium Microcystis aeruginosa PCC 7806 by a procedure including extraction of cells with water-saturated 1-butanol, chromatography of the extract on silica gel plates and high performance liquid chromatography (HPLC) on Partisil-5. The toxin was shown to be only a minor constituent, being negatively charged and thus separable by electrophoresis, within the HPLC-purified fraction. It contained erythro-beta-methyl-D-Asp, D-Glu, D-Ala, L-Leu, and L-Arg known to be part of the Microcystis peptide-toxin with Mr 994. The major part of the HPLC-purified fraction was assigned, however, to a nontoxic peptide with a Mr of 956. Partial hydrolysis studies of the nontoxic peptide(s) revealed amino acid sequences composed of D-Glu, N-methyl-Phe, and 3,4-dehydro-Pro, aside from the common L-amino acids. Cyclic linkage in the nontoxic peptide(s) appears likely.
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Affiliation(s)
- I M Birk
- Institut für Biologie II, Albert-Ludwigs-Universität, Freiburg, Federal Republic of Germany
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Meriluoto JA, Sandström A, Eriksson JE, Remaud G, Craig AG, Chattopadhyaya J. Structure and toxicity of a peptide hepatotoxin from the cyanobacterium Oscillatoria agardhii. Toxicon 1989; 27:1021-34. [PMID: 2508270 DOI: 10.1016/0041-0101(89)90153-0] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A peptide hepatotoxin was isolated by reversed phase liquid chromatography from the cyanobacterium Oscillatoria agardhii and characterized structurally and toxicologically. Amino acid analyses, proton nuclear magnetic resonance and fast atom bombardment mass spectrometry showed that the toxin is a cyclic heptapeptide (mol. wt 1023.5) with the structure cyclo-(Ala-Arg-Asp-Arg-Adda-Glu-N-methyldehydroAla) (Adda: 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid). In mice the toxic effects were restricted mainly to the liver where the toxin induced massive hemorrhages and a disruption of the lobular and sinusoidal structure. The i.p. LD50 of the toxin was 250 micrograms/kg. The structural and toxic properties of this peptide are very close to those of microcystins, cyclic peptide toxins produced by the cyanobacterium Microcystis aeruginosa.
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Affiliation(s)
- J A Meriluoto
- Department of Biochemistry and Pharmacy, Abo Akademi, Finland
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24
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Miura GA, Robinson NA, Geisbert TW, Bostian KA, White JD, Pace JG. Comparison of in vivo and in vitro toxic effects of microcystin-LR in fasted rats. Toxicon 1989; 27:1229-40. [PMID: 2617540 DOI: 10.1016/0041-0101(89)90031-7] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The toxic effects of microcystin-LR, a cyclic heptapeptide isolated from the cyanobacterium Microcystis aeruginosa, were studied in the fasted rat model and in subcellular fractions from fasted, toxin-treated and control rats. Hepatotoxic effects of a lethal dose (100 micrograms/kg) were examined 15-90 min post-injection. Elevations of serum enzymes, particularly sorbitol dehydrogenase, specific for liver mitochondria, correlated with hepatic damage. Electron micrographs showed progressive cellular disruption, including dilation of rough endoplasmic reticulum, incorporation of cellular components into cytolysosomes, hydropic mitochondria devoid of electron-opaque deposits, loss of desmosome-associated intermediate filaments, disruption of sinusoidal architecture and, ultimately, lysis of hepatocytes. The appearance of hydropic mitochondria correlated with loss of coupled electron transport. Changes in plasma membrane-associated cytoskeletal filaments correlated with loss of desmosome tonofilaments. In contrast to in vivo exposure to microcystin-LR, in vitro exposure to toxin had no effect on mitochondria or cytoskeletal filaments, suggesting that the toxic effects observed in vivo were indirect and may be dependent on bioactivation of the toxin or a cascade of events not supported in in vitro models.
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Affiliation(s)
- G A Miura
- Pathophysiology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21701-5011
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25
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Eriksson JE, Meriluoto JAO, Kujari HP, Al-Layl KJ, Codd GA. Cellular effects of cyanobacterial peptide toxins. ACTA ACUST UNITED AC 1988. [DOI: 10.1002/tox.2540030507] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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26
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Carmichael WW, He JW, Eschedor J, He ZR, Juan YM. Partial structural determination of hepatotoxic peptides from Microcystis aeruginosa (cyanobacterium) collected in ponds of central China. Toxicon 1988; 26:1213-7. [PMID: 3149051 DOI: 10.1016/0041-0101(88)90307-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Waterbloom samples of the colonial cyanobacterium Microcystis aeruginosa, collected in fish ponds at the Hydrobiological Institute, Wuhan, People's Republic of China, were hepatotoxic to mice. Lyophilized cells had an LD50 (i.p. mouse; 40 mg/kg) and signs of poisoning similar to that reported for other cyanobacterial hepatotoxic peptides. Two toxins, with an LD50 (i.p. mouse) of 40 and 150 micrograms/kg, were isolated using gel filtration and high performance liquid chromatography. The amino acid composition and mol. wt (994) of the 40 micrograms/kg toxin was the same as that for microcystin-LR, while the 150 micrograms/kg toxin had an amino acid composition and mol. wt (1048) different from any of the reported cyanobacteria heptapeptide toxins reported to date.
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Affiliation(s)
- W W Carmichael
- Department of Biological Sciences, Wright State University, Dayton, OH 45435
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