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Li B, Jin X, Chan HM. Effects of low doses of methylmercury (MeHg) exposure on definitive endoderm cell differentiation in human embryonic stem cells. Arch Toxicol 2023; 97:2625-2641. [PMID: 37612375 PMCID: PMC10475006 DOI: 10.1007/s00204-023-03580-7] [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: 07/13/2023] [Accepted: 08/03/2023] [Indexed: 08/25/2023]
Abstract
Fetal development is one of the most sensitive windows to methylmercury (MeHg) toxicity. Laboratory and epidemiological studies have shown a dose-response relationship between fetal MeHg exposure and neuro performance in different life stages from infants to adults. In addition, MeHg exposure has been reported to be associated with disorders in endoderm-derived organs, such as morphological changes in liver cells and pancreatic cell dysfunctions. However, the mechanisms of the effects of MeHg on non-neuronal organs or systems, especially during the early development of endoderm-derived organs, remain unclear. Here we determined the effects of low concentrations of MeHg exposure during the differentiation of definitive endoderm (DE) cells from human embryonic stem cells (hESCs). hESCs were exposed to MeHg (0, 10, 100, and 200 nM) that covers the range of Hg concentrations typically found in human maternal blood during DE cell induction. Transcriptomic analysis showed that sub-lethal doses of MeHg exposure could alter global gene expression patterns during hESC to DE cell differentiation, leading to increased expression of endodermal genes/proteins and the over-promotion of endodermal fate, mainly through disrupting calcium homeostasis and generating ROS. Bioinformatic analysis results suggested that MeHg exerts its developmental toxicity mainly by disrupting ribosome biogenesis during early cell lineage differentiation. This disruption could lead to aberrant growth or dysfunctions of the developing endoderm-derived organs, and it may be the underlying mechanism for the observed congenital diseases later in life. Based on the results, we proposed an adverse outcome pathway for the effects of MeHg exposure during human embryonic stem cells to definitive endoderm differentiation.
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Affiliation(s)
- Bai Li
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada
| | - Xiaolei Jin
- Regulatory Toxicology Research Division, Bureau of Chemical Safety, Food Directorate, HPFB, Health Canada, 251 Sir Frederick Banting Driveway, Ottawa, ON, K1A 0K9, Canada.
| | - Hing Man Chan
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada.
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Karlsen OA, Sheehan D, Goksøyr A. Alterations in the Atlantic cod (Gadus morhua) hepatic thiol-proteome after methylmercury exposure. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2014; 77:650-662. [PMID: 24754398 DOI: 10.1080/15287394.2014.887427] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Proteomic studies in general have demonstrated that the most effective and thorough analysis of biological samples requires subfractionation and/or enrichment prior to downstream processing. In the present study, Atlantic cod (Gadus morhua) liver samples were fractionated using activated thiol sepharose to isolate hepatic proteins containing free/reactive cysteines. This subset of proteins is of special interest when studying the physiological effects attributed to methylmercury (MeHg) exposure. Methylmercury is a persistent environmental contaminant that has a potent affinity toward thiol groups, and can directly bind proteins via available cysteine residues. Further, alterations in the cod thiol-proteome following MeHg exposure (2 mg/kg body weight) were explored with two-dimensional gel electrophoresis combined with downstream mass spectrometry analyses for protein identifications. Thirty-five protein spots were found to respond to MeHg exposure, and 13 of these were identified when searching cod-specific databases with acquired mass spectrometry data. Among the identified thiol-containing proteins, some are known to respond to MeHg treatment, including constituents of the cytoskeleton, and proteins involved in oxidative stress responses, protein synthesis, protein folding, and energy metabolism. Methylmercury also appeared to affect cod heme metabolism/turnover, producing significantly altered levels of hemoglobin and hemopexin in liver following metal exposure. The latter finding suggests that MeHg may also affect the hematological system in Atlantic cod.
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Affiliation(s)
- O A Karlsen
- a Department of Biology , University of Bergen , Bergen , Norway
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Salvaterra P, Lown B, Morganti J, Massaro EJ. Alterations in neurochemical and behavioral parameters in the mouse induced by low doses of methyl mercury. ACTA PHARMACOLOGICA ET TOXICOLOGICA 2009; 33:177-90. [PMID: 4800780 DOI: 10.1111/j.1600-0773.1973.tb01520.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Hultman P, Eneström S. Dose-response studies in murine mercury-induced autoimmunity and immune-complex disease. Toxicol Appl Pharmacol 1992; 113:199-208. [PMID: 1532866 DOI: 10.1016/0041-008x(92)90115-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Female SJL/N mice were given either 5.0, 2.5, 1.25, or 0.625 mg mercuric chloride per liter drinking water (ppm HgCl2). Serum antinucleolar antibodies (ANuA) of the IgG class were seen in mice given at least 1.25 ppm HgCl2 for 10 weeks, a dose which corresponded to a mean renal mercury concentration, as measured with atomic absorption spectrophotometry, of 2.4 +/- 0.43 microgram Hg/g wet weight (ppm Hg; means +/- 1 SD). At a dose of 5.0 ppm HgCl2 all mice showed IgG ANuA with a mean titer of 1:846 and a mean renal mercury concentration of 14.8 +/- 3.9 ppm. Significantly increased titers of granular IgG deposits, corresponding to immune-complex (IC) deposits, developed in the renal mesangium of mice given 5.0 ppm HgCl2. Mice with heavy mesangial IgG deposits showed a mild glomerular endocapillary cell proliferation and widening of the mesangium. Renal vessel wall IgG deposits were found only in mice given 5.0 ppm HgCl2, whereas such deposits were seen in splenic and cardiac arteries of mice receiving 1.25 ppm or more of HgCl2. The renal and splenic mercury concentration was significantly increased in all groups of mercuric chloride-exposed mice and correlated with the dose. We conclude that 10 weeks peroral treatment with mercuric chloride in drinking water is able to elicit autoimmunity and IC disease in genetically homogeneous, mercury-sensitive mice at a body burden similar to that reported in some occupationally exposed humans.
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Affiliation(s)
- P Hultman
- Department of Pathology I, Linköping University, Sweden
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Curle DC, Ray M, Persaud TV. In vivo evaluation of teratogenesis and cytogenetic changes following methylmercuric chloride treatment. Anat Rec (Hoboken) 1987; 219:286-95. [PMID: 3425947 DOI: 10.1002/ar.1092190309] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Mercury is a major environmental pollutant and a proven teratogen in man and animals. Its teratogenicity and effects on fetal chromosomes were investigated in mice. Various dose levels of methylmercuric chloride (MMC) were administered via an intragastric tube to pregnant ICR Swiss/Webster mice on day 9 of gestation. On day 18 of gestation the animals were killed and the fetuses were removed. Fetal lung and liver tissues were processed for cytogenetic studies. Fetuses were also fixed in Bouin's solution for subsequent teratological examination by using Wilson's technique. Mercury levels were determined in maternal blood and randomly selected fetuses. One fetus from each litter was processed for skeletal staining with Alizarin Red S. A significant increase in embryonic deaths and resorptions was observed at all dose levels. The incidence of fetal anomalies was significantly increased following maternal treatment with 10, 15, or 20 mg/kg of MMC. Maternal weight between day 9 and day 18 of gestation decreased significantly. The LD50 of MMC in pregnant mice was determined to be 20 mg/kg of body weight; the LD100 was 30 mg/kg. A significant difference was observed between the mean fetal weights at the various dose levels. Levels of mercury were found to be significantly higher in treated animals and fetuses, and increased in a dose-related manner. The levels of mercury were significantly higher in the fetuses than in the mothers at the same dosage, indicating a correlation between the levels of mercury in maternal mice and corresponding higher levels in their fetuses. Cytogenetic studies revealed significant clumping of chromosomes in metaphase at all dose levels and the frequency of clumping increased as dosage increased. The euploidy number (2n = 40) of chromosomes per cell did not vary between the treatment groups and control groups. The frequency of nucleolus-organizing regions per cell did not change significantly between the treatment groups and the control. The frequency of sister chromatid exchanges increased significantly as the dosage increased.
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Affiliation(s)
- D C Curle
- Department of Anatomy, University of Manitoba, Winnipeg, Canada
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Hurst R, Schatz JR, Matts RL. Inhibition of rabbit reticulocyte lysate protein synthesis by heavy metal ions involves the phosphorylation of the alpha-subunit of the eukaryotic initiation factor 2. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47679-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Cloëz I, Dumont O, Piciotti M, Bourre JM. Alterations of lipid synthesis in the normal and dysmyelinating trembler mouse sciatic nerve by heavy metals (Hg, Pb, Mn, Cu, Ni). Toxicology 1987; 46:65-71. [PMID: 3660421 DOI: 10.1016/0300-483x(87)90138-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Lipid synthesis from 14C-labeled acetate was dramatically reduced by inorganic mercury in the mouse sciatic nerve in vitro (IC50 was 10 microM). The dysmyelinating trembler mutant was less affected (IC50 was 40 microM). Under the same conditions, lipid synthesis was less inhibited by inorganic lead but was increased 3 times by manganese, copper and nickel at less than 2 mM. Although the synthesis of all lipids is dramatically reduced by inorganic mercury, their relative proportions vary in the presence of this metal:cholesterol synthesis was inhibited most strongly, phosphatidylcholine synthesis was also reduced, whereas synthesis of other lipids was relatively unchanged (phosphatidylserine, phosphatidyl inositol, sphingomyelin, cholesterol esters, cerebrosides). Incorporation of [14C]acetate into free fatty acids was enhanced by a factor of 4 in the presence of inorganic mercury.
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Affiliation(s)
- I Cloëz
- INSERM U26 Hôpital F. Widal, Paris, France
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Abstract
Although a large number of epidemiological, clinical, and pathological studies on methylmercury intoxication have been published, these investigations have not been able to elucidate the detailed mechanisms by which the metal alkyl causes a wide variety of biological dysfunctions. Thus, the cultured cells which are free from the influence of whole body complexities, such as absorption, distribution, metabolism, etc., which complicate the interpretation of in vivo experimental results, attract the attention of many scientists who are interested in clarifying the mode of toxic action of methylmercury. The aim of this article is to review the recent studies on the toxicity of methylmercury at the cellular level and to outline the mechanisms which have been proposed to be responsible for cell injuries.
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Affiliation(s)
- K Miura
- Department of Public Health, Kitasato University, Tokyo, Japan
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Sauvé GJ, Nicholls DM. Liver protein synthesis during the acute response to methylmercury administration. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1981; 13:981-90. [PMID: 7297752 DOI: 10.1016/0020-711x(81)90003-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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12
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Mehra M, Kanwar KC. Biochemical changes resulting from the intraperitoneal administration of mercuric chloride and methylmercuric chloride to mice. Toxicol Lett 1980; 6:319-26. [PMID: 6158769 DOI: 10.1016/0378-4274(80)90137-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
I.p. administration of mercuric chloride (HgCl2) and methylmercuric chloride (MeHgCl) at 1 mg/kg body wt./day for 10 consecutive days markedly influenced the phospholipid, DNA, RNA and protein of various tissues of mice. HgCl2 led to a significant increase (42%) in the liver phospholipid content but to a similar decrease in kidney phospholipid. MeHgCl reduced the phospholipid content of the brain and kidney. Kidney DNA decreased following administration of both HgCl2 and MeHgCl. MeHgCl resulted in the depleted rates of 32P uptake in the DNA fraction of all tissues studied. Both compounds increased liver and testis RNA and reduced the protein content and the 32P uptake from the protein fraction in all tissues studied.
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Grundt IK, Stensland E, Syverson TL. Changes in fatty acid composition of myelin cerebrosides after treatment of the developing rat with methylmercury chloride and diethylmercury. J Lipid Res 1980. [DOI: 10.1016/s0022-2275(20)39821-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Gagnon MJ, Couture C. Effect of spironolactone and PCN (pregnenolone-16-alpha-carbonitrile) on the hepatotoxicity induced by dimethylmercury in rat. GENERAL PHARMACOLOGY 1980; 11:555-9. [PMID: 7461434 DOI: 10.1016/0306-3623(80)90090-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Chen WJ, Body RL, Mottet NK. Some effects of continuous low-dose congenital exposure to methylmercury on organ growth in the rat fetus. TERATOLOGY 1979; 20:31-6. [PMID: 515962 DOI: 10.1002/tera.1420200107] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Congenital low-dose exposure of rat fetuses to methylmercury produced smaller offspring without anatomical abnormalities. The present study explored the mechanisms of the smallness of fetuses. The pregnant rats were given methylmercury water (25 ppm) from day 1 of pregnancy continuously until day 20 of gestation. There was a negative correlation of fetal weight and maternal and fetal mercury burden. The whole organ DNA and protein content of the livers and kidneys in the experiments were significantly lower than the control (P less than 0.05) indicating that there were fewer cells per organ in the mercury exposed fetuses. When the data were compared on a per gram of tissue basis, there was no significanct difference, indicating that the number and size of the cells of each were not diminished. The incorporation of 3H-thymidine into fetal tissue DNA was also substantially lower in the experimental group indicating decreased proliferative activity. We conclude from this study that, at least for some major organs, the decreased size in the mercury exposed fetuses is due to fewer cells in the organs due to decreased proliferative activity.
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Kasschau MR, Elder J, Meyn RE. Effects of mercuric chloride on synchronized Chinese hamster ovary cells: survival and DNA replication. Chem Biol Interact 1977; 18:205-15. [PMID: 560920 DOI: 10.1016/0009-2797(77)90007-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Chinese hamster ovary (CHO) cells in vitro were treated with HgCl2 at various stages in the cell cycle and the effects of this chemical on cell survival, DNA replication, and cell division were observed. In terms of survival the early G1 cells were the most sensitive to treatment, followed by late G1 and early S, while mid S and late S-G2 treated cells were the least sensitive. Treatment with HgCl2 also resulted in reduced rates of DNA replication and delays in cell division. The early G1 treated cells showed substantially reduced rates of DNA replication followed by 4--5 h division delay. The early S and late S-G2 treated cells had some reduction in their rates of DNA replication followed by corresponding division delay of 2.5 h in the early S treated cells and 1 h in the late S-G2 treated cells.
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SYVERSEN TLM. EFFECTS OF METHYLMERCURY ON IN VIVO PROTEIN SYNTHESIS IN ISOLATED CEREBRAL AND CEREBELLAR NEURONS. Neuropathol Appl Neurobiol 1977. [DOI: 10.1111/j.1365-2990.1977.tb00586.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Koos BJ, Longo LD. Mercury toxicity in the pregnant woman, fetus, and newborn infant. A review. Am J Obstet Gynecol 1976; 126:390-409. [PMID: 786026 DOI: 10.1016/0002-9378(76)90557-3] [Citation(s) in RCA: 106] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This paper reviews the reported cases of mercury poisoning in pregnancy and the data based on sources of contamination, maternal uptake, and distribution. It analyzes current knowledge of placental transfer of various mercury compounds, fetal uptake, and distribution. It identifies the embryopathic and fetal toxic effects of mercury in general while emphasizing the greater toxicity of methylmercury compounds. Since maternal exposure to methylmercury is primarily through fish consumption, it recommends that women of childbearing age should not consume more than 350 Gm. of fish per week. In addition, they should not be occupationally exposed to air concentrations of mercury vapor greater than 0.01 mg. per cubic meter, of inorganic and phenylmercuric compounds greater than 0.02 mg. per cubic meter, or any detectable concentration of methylmercury.
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Richardson RJ, Murphy SD. Neurotoxicity produced by intracranial administration of methylmercury in rats. Toxicol Appl Pharmacol 1974; 29:289-300. [PMID: 4283694 DOI: 10.1016/0041-008x(74)90066-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Brubaker PE, Klein R, Herman SP, Lucier GW, Alexander LT, Long MD. DNA, RNA, and protein synthesis in brain, liver, and kidneys of asymptomatic methylmercury treated rats. Exp Mol Pathol 1973; 18:263-80. [PMID: 4708308 DOI: 10.1016/0014-4800(73)90024-5] [Citation(s) in RCA: 78] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Chang LW, Desnoyers PA, Hartmann HA. Quantitative cytochemical studies of RNA in experimental mercury poisoning. II. Changes in the base composition and ratios. Acta Neuropathol 1973; 23:77-83. [PMID: 4698525 DOI: 10.1007/bf00689006] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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