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Lange A, Segner H. The Role of Glutathione and Sulfhydryl Groups in Cadmium Uptake by Cultures of the Rainbow Trout RTG-2 Cell Line. Cells 2023; 12:2720. [PMID: 38067148 PMCID: PMC10705847 DOI: 10.3390/cells12232720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 11/21/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
The aim of this study is to investigate the role of cellular sulfhydryl and glutathione (GSH) status in cellular cadmium (Cd) accumulation using cultures of the rainbow trout cell line RTG-2. In a first set of experiments, the time course of Cd accumulation in RTG-2 cells exposed to a non-cytotoxic CdCl2 concentration (25 μM) was determined, as were the associated changes in the cellular sulfhydryl status. The cellular levels of total GSH, oxidized glutathione (GSSG), and cysteine were determined with fluorometric high-performance liquid chromatography (HPLC), and the intracellular Cd concentrations were determined with inductively coupled plasma mass spectrometry (ICP-MS). The Cd uptake during the first 24 h of exposure was linear before it approached a plateau at 48 h. The metal accumulation did not cause an alteration in cellular GSH, GSSG, or cysteine levels. In a second set of experiments, we examined whether the cellular sulfhydryl status modulates Cd accumulation. To this end, the following approaches were used: (a) untreated RTG-2 cells as controls, and (b) RTG-2 cells that were either depleted of GSH through pre-exposure to 1 mM L-buthionine-SR-sulfoximine (BSO), an inhibitor of glutathione synthesis, or the cellular sulfhydryl groups were blocked through treatment with 2.5 μM N-ethylmaleimide (NEM). Compared to the control cells, the cells depleted of intracellular GSH showed a 25% reduction in Cd accumulation. Likewise, the Cd accumulation was reduced by 25% in the RTG-2 cells with blocked sulfhydryl groups. However, the 25% decrease in cellular Cd accumulation in the sulfhydryl-manipulated cells was statistically not significantly different from the Cd accumulation in the control cells. The findings of this study suggest that the intracellular sulfhydryl and GSH status, in contrast to their importance for Cd toxicodynamics, is of limited importance for the toxicokinetics of Cd in fish cells.
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Fenton PC, Turner CJ, Hogstrand C, Bury NR. Fluid shear stress affects the metabolic and toxicological response of the rainbow trout gill cell line RTgill-W1. Toxicol In Vitro 2023; 90:105590. [PMID: 36997009 DOI: 10.1016/j.tiv.2023.105590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/20/2023] [Accepted: 03/23/2023] [Indexed: 03/30/2023]
Abstract
The Rainbow trout gill cell-line (RTgill-W1) has been accepted by the Organisation for Economic Co-operation and Development (OECD TG249) as a replacement for fish in acute toxicity tests. In these tests cells are exposed under static conditions. In contrast, in vivo, water moves over fish gills generating fluid shear stress (FSS) that alters cell physiology and response to toxicants. The current study uses a specialised 3D printed chamber designed to house inserts and allows for the flow (0.2 dynes cm2) of water over the cells. This system was used to assess RTgill-W1 cell responses to FSS in the absence and presence of copper (Cu) over 24 h. FSS caused increased gene expression of mechanosensitive channel peizo1 and the Cu-transporter atp7a, elevated reactive oxygen species generation and increased expression of superoxidase dismutase. Cell metabolism was unaffected by Cu (0.163 μM to 2.6 μM Cu) under static conditions but significantly reduced by FSS + Cu above 1.3 μM. Differential expression of metallothionein (mt) a and b was observed with increased expression of mta under static conditions and mtb under FSS on exposure to Cu. These findings highlight toxicologically relevant mechanosensory responses by RTgill-W1 to FSS that may influence toxicological responses.
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Isani G, Carpenè E. Metallothioneins, unconventional proteins from unconventional animals: a long journey from nematodes to mammals. Biomolecules 2014; 4:435-57. [PMID: 24970224 PMCID: PMC4101491 DOI: 10.3390/biom4020435] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/19/2014] [Accepted: 03/21/2014] [Indexed: 12/19/2022] Open
Abstract
Metallothioneins (MTs) are ubiquitous low molecular weight cysteine-rich proteins characterized by high affinity for d10 electron configuration metals, including essential (Zn and Cu) and non-essential (Cd and Hg) trace elements. The biological role of these ancient and well-conserved multifunctional proteins has been debated since MTs were first discovered in 1957. Their main hypothesized functions are: (1) homeostasis of Zn and Cu; (2) detoxification of Cd, and Hg; and (3) free radical scavenging. This review will focus on MTs in unconventional animals, those not traditionally studied in veterinary medicine but of increasing interest in this field of research. Living in different environments, these animals represent an incredible source of physiological and biochemical adaptations still partly unexplored. The study of metal-MT interactions is of great interest for clinicians and researchers working in veterinary medicine, food quality and endangered species conservation.
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Affiliation(s)
- Gloria Isani
- Department of Veterinary Medical Sciences, Alma Mater Studiorum-University of Bologna, via Tolara di sopra, 50, Ozzano Emilia, Bologna 40064, Italy.
| | - Emilio Carpenè
- Department of Veterinary Medical Sciences, Alma Mater Studiorum-University of Bologna, via Tolara di sopra, 50, Ozzano Emilia, Bologna 40064, Italy.
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Vergani L. Metallothioneins in Aquatic Organisms: Fish, Crustaceans, Molluscs, and Echinoderms. METALLOTHIONEINS AND RELATED CHELATORS 2009. [DOI: 10.1039/9781847559531-00199] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Metallothioneins (MTs) have been described in a wide range of organisms, from bacteria to mammals, thus representing an interesting example of evolutionary molecular adaptation. If the moderate variability of MTs across phylogenetically distant organisms reflects their highly conserved function, the specific environmental requirements may explain the multiplicity of isoforms also in the same organism. The MT polymorphism is particularly important in invertebrates with respect to vertebrates. This review is an attempt to summarize the knowledge about MTs from aquatic animals, both vertebrates and invertebrates, to gain new insights into the structure-function relationship of this class of proteins. The large and increasing literature on MTs indicates that MTs from aquatic vertebrates are rather similar to mammalian counterparts, whereas a variety of structures have been described in invertebrates. Although the prototypical αβ-domain organization of vertebrate MTs has been observed in most invertebrate isoforms, some invertebrate MTs display alternative structures in which the canonical organization has been modified, such as the ββ-domain, the αββ-domain, and the multiple α-domain structures of oyster MTs, and the inverted βα-domain organization of sea urchin MTs. In this review we emphasize three major taxa of aquatic invertebrates, the molluscs, the crustaceans and the echinoderms, although some data have been reported for other invertebrates.
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Affiliation(s)
- Laura Vergani
- Department of Biology, University of Genova I-16132 Genova Italy
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5
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Trinchella F, Riggio M, Filosa S, Parisi E, Scudiero R. Molecular cloning and sequencing of metallothionein in squamates: New insights into the evolution of the metallothionein genes in vertebrates. Gene 2008; 423:48-56. [DOI: 10.1016/j.gene.2008.06.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Revised: 06/18/2008] [Accepted: 06/23/2008] [Indexed: 12/11/2022]
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6
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Aldo Viarengo, Bruno Burlando, Fran. Metallothionein as a tool in biomonitoring programmes. Biomarkers 2008; 4:455-66. [DOI: 10.1080/135475099230615] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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7
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Vergani L, Lanza C, Borghi C, Scarabelli L, Panfoli I, Burlando B, Dondero F, Viarengo A, Gallo G. Efects of growth hormone and cadmium on the transcription regulation of two metallothionein isoforms. Mol Cell Endocrinol 2007; 263:29-37. [PMID: 17027146 DOI: 10.1016/j.mce.2006.08.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 08/16/2006] [Accepted: 08/16/2006] [Indexed: 11/17/2022]
Abstract
The effect of growth hormone (GH) and cadmium (Cd) on metallothionein (MT) expression was investigated in hepatoma cells. In fish the constitutive isoform MT-B and the metal-responsive MT-A are expressed. Real-time RT-PCR revealed that: Cd up-regulates mostly MT-A, GH slightly induces MT-B and the GH/Cd combination induces synergistically both MTs. Perturbations in Ca2+ levels suppressed or reduced the Cd-induction of MTs and abolished the GH/Cd synergy. Similar results were obtained by inhibition of tyrosine kinases. Also the signaling molecules recruited by the GH receptor responded differently to GH and Cd, with ERKs showing a synergistic activation upon GH/Cd. The following conclusions can be drawn: (1) cytosolic Ca2+ is mainly involved in MT-A regulation; (2) both Ca2+ and tyrosine phosphorylation are essential for Cd-induction and GH/Cd synergy on MTs. The synergy could depend on interactions in different signaling pathways, leading to a differential recruitment of MTF-1 and AP-1 transcription factors.
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Affiliation(s)
- Laura Vergani
- Department of Biophysical Sciences and Technologies M. & O (DISTBIMO), University of Genoa, Largo Rosanna Benzi 10, 16132 Genova, Italy.
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8
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Scudiero R, Carginale V, Capasso C, Riggio M, Filosa S, Parisi E. Structural and functional analysis of metal regulatory elements in the promoter region of genes encoding metallothionein isoforms in the Antarctic fish Chionodraco hamatus (icefish). Gene 2001; 274:199-208. [PMID: 11675012 DOI: 10.1016/s0378-1119(01)00609-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
To investigate the regulation of Chionodraco hamatus metallothionein (MT) encoding genes about 1000-bp regions of both MT-I and MT-II gene promoters were cloned and sequenced. Both promoters were rich in A-T content, and lacked the canonical TATA box; several putative cis-regulatory sequences were also present. In the MT-I promoter, four MREs were identified within the first 300 bp from the ATG codon. In the MT-II promoter, seven MREs were organized into two clusters, one containing three MREs located close to the ATG codon, and the other consisting of four MREs lying 500-900 bp upstream of the transcription starting point. The alignment of the MT-I and MT-II promoter regions showed 57% identity, which increased to 87% in the 300-bp region upstream of the ATG. Only the three proximal putative MREs identified were conserved both in position and sequence. Functional analysis of MT-I and MT-II promoters was performed by introducing deletion mutants of the 5'-flanking regions into vector pGL-3, directly upstream of the firefly luciferase reporter gene. Each construct was tested in the HepG2 cell lines in the absence or presence of zinc or cadmium ions. Maximum inducibility of the MT-II gene promoter was achieved with a construct containing both the proximal and the distal MRE clusters. The lack of the most distally located MRE dramatically affected MT-II promoter sensitivity to metals; removal of the distal cluster of MREs also reduced metal inducibility. The MT-I promoter was more compact, since maximal activity and metal inducibility depended on the presence of the proximal cluster of four MREs. This study suggests that the different organization of the MT-I and MT-II gene promoter regions might account for the observed differences in the basal and metal-induced expression of MT-I and MT-II isoforms in the C. hamatus liver.
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Affiliation(s)
- R Scudiero
- Dipartimento di Biologia Evolutiva e Comparata, Università Federico II, Napoli, Italy
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Samson SL, Paramchuk WJ, Gedamu L. The rainbow trout metallothionein-B gene promoter: contributions of distal promoter elements to metal and oxidant regulation. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1517:202-11. [PMID: 11342100 DOI: 10.1016/s0167-4781(00)00273-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this report, the contributions of the distal 5'-regulatory sequences of the rainbow trout (Oncorhynchus mykiss) metallothionein (tMT)-B gene promoter (-738 to +5) were studied. Transfection of the -738 promoter fragment in a rainbow trout hepatoma cell line (RTH-149) resulted in 4- to 5-fold greater activity compared to the proximal -137 promoter region. Mutation of the proximal MREa abolishes the basal activity of the -738 fragment indicating that the distal regulatory elements require a cooperative interaction with MREa. However, the fragments containing both distal MREs, c and d (positioning -570 and -680, respectively), or MREc alone could confer basal and metal-induced activity when fused to the TATA box. This suggests that these distal elements are functional and therefore may play a role as basal elements in their natural state. The trout MT genes are also induced by oxidants including H2O2, tBHP and tBHQ. The larger promoter fragment -738 responds to H2O2, while the -137 fragment does not. However, fusion of the isolated MREc fragment (-648 to -533) in its native orientation, upstream of the -137 promoter elicits a response to H2O2, although no response is seen with MREc in reverse. These data suggest that this distal fragment contains functional oxidant responsive elements which have resemblance to the mammalian antioxidant responsive element (AREs).
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Affiliation(s)
- S L Samson
- Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
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Carvan MJ, Solis WA, Gedamu L, Nebert DW. Activation of transcription factors in zebrafish cell cultures by environmental pollutants. Arch Biochem Biophys 2000; 376:320-7. [PMID: 10775418 DOI: 10.1006/abbi.2000.1727] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Many classes of environmental pollutants are found at significant levels in the aquatic environment. We are designing a fish model as an inexpensive and efficient system for the assessment of aquatic pollution. Three classes of environmental pollutants-halogenated and nonhalogenated aromatic hydrocarbons, heavy metals, and potent electrophiles-are known to upregulate particular mammalian genes via the activation of specific DNA motifs called aromatic hydrocarbon (AHREs), heavy metal (MREs), and electrophile (EPREs) response elements, respectively. We have made plasmid constructs, using these mammalian or trout response elements to drive the luciferase reporter gene. Here we show that transient transfection of the zebrafish ZEM2S cell line with these reporter constructs imparts dose-dependent gene induction upon exposure to a variety of chemicals within each of these three classes of inducers: [a] (AHRE-mediated) 2,3,7,8-tetrachlorodibenzo-p-dioxin, 3-methylcholanthrene, 3,4,5,3',4',5'-hexabromobiphenyl, Aroclor 1254, and benzo[a]pyrene; [b] (MRE-mediated) Cd(2+), Zn(2+), Hg(2+), and Al(3+); and [c] (EPRE-mediated) tert-butylhydroquinone, Hg(2+), Pb(2+), As(3+), Cu(2+), and Cd(2+). As expected, some agents gave a response to only one of the three classes, whereas others gave a mixed (AHRE- plus EPRE-mediated or MRE- plus EPRE-mediated) response. In response to several environmental agents, we found that differences in the electrophoretic mobility shift assay, using the AHRE or MRE as probe, were consistent with the degree of transcriptional activation seen with the reporter constructs. Our data suggest that these reporter constructs might be valuable for the generation of transgenic zebrafish in order to carry out mechanistic and developmental studies of transcriptional activation by environmental contaminants; moreover, such transgenic zebrafish lines might be useful as a sentinel for assessing aquatic pollution.
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MESH Headings
- Animals
- Animals, Genetically Modified
- Cells, Cultured
- DNA Probes
- Dose-Response Relationship, Drug
- Electrons
- Enhancer Elements, Genetic/genetics
- Genes, Reporter/genetics
- Genetic Vectors/genetics
- Halogens/metabolism
- Hydrocarbons, Aromatic/metabolism
- Hydrocarbons, Aromatic/pharmacology
- Hydrogen Peroxide/pharmacology
- Hydroquinones/pharmacology
- Ligands
- Metals, Heavy/pharmacology
- Promoter Regions, Genetic/genetics
- Receptors, Aryl Hydrocarbon/metabolism
- Response Elements/genetics
- Transcription Factors/metabolism
- Transcriptional Activation/drug effects
- Water Pollutants/pharmacology
- Zebrafish
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Affiliation(s)
- M J Carvan
- Center for Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, Ohio 45267-0056, USA.
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11
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Abstract
In aquatic toxicology, cytotoxicity tests using continuous fish cell lines have been suggested as a tool for (1) screening or toxicity ranking of anthropogenic chemicals, compound mixtures and environmental samples, (2) establishment of structure-activity relationships, and (3) replacement or supplementation of in vivo animal tests. Due to the small sample volumes necessary for cytotoxicity tests, they appear to be particularly suited for use in chemical fractionation studies. The present contribution reviews the existing literature on cytotoxicity studies with fish cells and considers the influence of cell line and cytotoxicity endpoint selection on the test results. Furthermore, in vitro/in vivo correlations between fish cell lines and intact fish are discussed. During recent years, fish cell lines have been increasingly used for purposes beyond their meanwhile established role for cytotoxicity measurements. They have been successfully introduced for detection of genotoxic effects, and cell lines are now applied for investigations on toxic mechanisms and on biomarkers such as cytochrome P4501A. The development of recombinant fish cell lines may further support their role as a bioanalytical tool in environmental diagnostics.
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Affiliation(s)
- H Segner
- Department of Chemical Ecotoxicology, Centre for Environmental Research, Leipzig, Germany
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12
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Samson SL, Gedamu L. Molecular analyses of metallothionein gene regulation. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1998; 59:257-88. [PMID: 9427845 DOI: 10.1016/s0079-6603(08)61034-x] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Metallothionein (MT) genes encode small proteins that chelate metal ions through metal-thiolate bonds with cysteine residues. MTs may have a role in cellular zinc homeostasis and metal detoxification. Congruent with these putative functions, MT gene transcription is induced by metals via multiple metal-responsive elements (MREs) present in the MT gene 5'-regulatory regions. This chapter mainly is focused on studies of the functional and physical interactions of MRE binding proteins with MT promoters from human and rainbow trout. In addition to mediating zinc induction, MREs may make important contributions to nonmetal induced promoter activity. In part, differential basal activity of MREs appears to be determined by sequence and position in the promoter. During zinc induction, increased functional MRE activity correlates with increased activity of mammalian MRE binding proteins by zinc treatment in vivo or in vitro, as detected by electrophoretic mobility shift assays. Interestingly, the addition of cadmium in vitro or in vivo has no detectable effect even though it strongly induces MT gene expression in the same time course. This raises questions about how the effects of cadmium are mediated by MREs. The molecular masses and MRE complex migration of the zinc-responsive factors we detect are consistent with mouse and human metal-responsive transcription factor (MTF) and expression of the MTF cDNAs increases co-transfected MT promoter activity in both mammalian and trout cell lines underlining the conservation of MRE binding factor function among diverse species.
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Affiliation(s)
- S L Samson
- Department of Biological Sciences, University of Calgary, Alberta
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13
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Gagné F, Blaise C, Bermingham N. Lethal and sublethal effects of marine sediment extracts on rainbow trout hepatocytes. Toxicol Lett 1996; 87:85-92. [PMID: 8914615 DOI: 10.1016/0378-4274(96)03764-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Genotoxicity and cytotoxicity were evaluated in rainbow trout hepatocytes exposed to organic sediment extracts obtained from Pointe aux Meules harbour in the Magdalen Islands, Canada. Hepatocytes were exposed to concentrations of sediment extracts for 24 h at 15 degrees C. After this incubation period, they were analyzed for viability, cytochrome P450 1A activity, and genotoxicity. Metallothionein (MT) levels were also determined in order to assess heavy metal exposure. All sediment extracts displayed cytotoxicity to rainbow trout hepatocytes. Half (53%) of the extracts proved to be genotoxic to trout hepatocytes, while cytochrome P450 1A induction occurred with 70% of the sediment extracts. Interestingly, 40% of the extracts had the capacity to elicit induction of MT in trout hepatocytes. MT induction by exposure of trout hepatocyte to organic extracts suggests the presence of metals. The lack of correlation between the chemical and toxicological data suggests that chemical interactions may be responsible for the toxic manifestations in trout hepatocytes or that unknown chemicals are at play.
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Affiliation(s)
- F Gagné
- St. Lawrence Centre, Environment Canada, Montreal, Quebec, Canada
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14
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Uses of Biotechnology to Enhance Production. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0167-9309(96)80020-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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15
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Olsson PE, Kling P, Erkell LJ, Kille P. Structural and functional analysis of the rainbow trout (Oncorhyncus mykiss) metallothionein-A gene. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 230:344-9. [PMID: 7601121 DOI: 10.1111/j.1432-1033.1995.tb20569.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In the present study, the distal part of the 5'-flanking region of the rainbow trout metallothionein-A promoter was sequenced in order to identify cis-acting regulatory elements. Analysis of this sequence combined with that previously reported for the 5'-flanking region directly proximal to the start of transcription revealed several putative regulatory sequences. In total, six metal-responsive elements (MREs) were identified; these sequences were organised into two clusters, one containing two copies of MRE and located close to the predicted TATA box sequence, and a second consisting of four MREs and lying 500-700 bp upstream from the start of transcription. In addition, the 5'-flanking region contained sequences sharing high similarity with the activator protein 1 consensus sequence as well as one nuclear-factor-interleukin-6-responsive element. Functional analysis of the promoter was performed by introducing deletion mutants of the 5'-flanking region into the vector pGL-2, directly upstream from the luciferase reporter gene. Both MRE clusters were needed for maximal metal inducibility in both rainbow trout hepatoma (RTH-149) and human hepatoblastoma (Hep G2) cell lines. Furthermore, the distal region was found to be functional in promoting gene transcription following exposure of RTH-149 cells to hydrogen peroxide.
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Affiliation(s)
- P E Olsson
- Department of Cellular and Developmental Biology, Umeå University, Sweden
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16
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Wan M, Hunziker PE, Kägi JH. Induction of metallothionein synthesis by cadmium and zinc in cultured rabbit kidney cells (RK-13). Biochem J 1993; 292 ( Pt 2):609-15. [PMID: 8503893 PMCID: PMC1134254 DOI: 10.1042/bj2920609] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The effects of increasing concentrations of Zn(II) and Cd(II) on the expression of the four isometallothioneins (isoMTs), namely MT-1a, MT-2a, MT-2d and MT-2e, in rabbit kidney cells (RK-13) and the development of cellular tolerance to these metal ions were studied. The results showed that, whereas in parental cells MT concentration was low and composed nearly exclusively of MT-2a and MT-1a, all four isoMTs increased massively in abundance when the cells were exposed to toxic concentrations of Zn(II) or Cd(II), the relative increase being largest in the two minor isoforms MT-2d and MT-2e. While the response of the four isoMTs to the challenge by Zn(II) or Cd(II) was qualitatively comparable, there were differences in sensitivity and delay time, Cd(II) being the more efficient inducer and much faster in eliciting the onset of isoMT synthesis. An even larger production of isoMTs resulted when RK-13 cells were cultured in the presence of a series of metal concentrations yielding sub-lines of increased metal tolerance. In this instance too, there were marked differences in the response to Cd(II) and Zn(II). Thus, in cells of sub-lines selected for tolerance to moderate concentrations of Cd(II) the kinetic analysis of isoMT accretion gave indications of a saturable induction process while no such evidence was forthcoming for Zn(II). In sub-line cells selected for tolerance to the highest concentrations of Cd(II) or Zn(II) isoMT formation was increased by another order of magnitude, reaching for some isoforms a 100- to 1000-fold augmentation over the amounts measured in cells of the unexposed parental cells. A potentiation of this magnitude goes beyond the range of ordinary regulation of gene expression. It is to be viewed instead as an enlargement of the capacity of isoMT synthesis acquired by a variety of mechanisms in the surviving cells.
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Affiliation(s)
- M Wan
- Biochemisches Institut, Universität Zürich, Switzerland
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17
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Technology and uses of cell cultures from the tissues and organs of bony fish. Cytotechnology 1991; 6:163-87. [DOI: 10.1007/bf00624756] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/1991] [Accepted: 06/11/1991] [Indexed: 10/26/2022] Open
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