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González-Dávila M, Maldonado MT, González AG, Guo J, González-Santana D, Martel A, Santana-Casiano JM. Cu transport and complexation by the marine diatom Phaeodactylum tricornutum: Implications for trace metal complexation kinetics in the surface ocean. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 919:170752. [PMID: 38340864 DOI: 10.1016/j.scitotenv.2024.170752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/30/2024] [Accepted: 02/04/2024] [Indexed: 02/12/2024]
Abstract
Elucidating whether dissolved Cu uptake is kinetically or thermodynamically controlled, and the effects of speciation on Cu transport by phytoplankton will allow better modeling of the fate and impact of dissolved Cu in the ocean. To address these questions, we performed Cu physiological and physicochemical experiments using the model diatom, Phaeodactylum tricornutum, grown in natural North Atlantic seawater (0.44 nM Cu). Using competitive ligand equilibration-cathodic stripping voltammetry (CLE-CSV), we measured two organic ligand types released by P. tricornutum to bind Cu (L1 and L2) at concentrations of ~0.35 nM L1 and 1.3 nM L2. We also established the presence of two putative Cu-binding sites at the cell surface of P. tricornutum (S1 and S2) with log K differing by ~5 orders of magnitude (i.e., 12.9 vs. 8.1) and cell surface densities by 9-fold. Only the high-affinity binding sites, S1, exhibit reductase activity. Using voltammetric kinetic measurements and a theoretical kinetic model, we calculated the forward and dissociation rate constants of L1 and S1. Complementary 67Cu uptake experiments identified a high- and a low-affinity Cu uptake system in P. tricornutum, with half-saturation constant (Km) of 154 nM and 2.63 μM dissolved Cu, respectively. In the P. tricornutum genome, we identified a putative high-affinity Cu transporter (PtCTR49224) and a putative ZIP-like, low-affinity Cu transporter (PtZIP49400). PtCTR49224 has high homology to Homo sapiens hCTR1, which depending on the accessibility to extracellular reducing agents, the hCTR1 itself is involved in the reduction of Cu2+ to Cu+ before internalization. We combined these physiological and physicochemical data to calculate the rate constants for the internalization of Cu, and established that while the high-affinity Cu uptake system (S1) is borderline between a kinetically or thermodynamically controlled system, the low-affinity Cu transporters, S2, is thermodynamically-controlled. We revised the inverse relationship between the concentrations of inorganic complexes of essential metals (i.e., Ni, Fe, Co, Zn, Cd, Mn and Cu) in the mixed layer and the formation rate constant of metal transporters in phytoplankton, highlighting the link between the chemical properties of phytoplankton metal transporters and the availability and speciation of trace metals in the surface ocean.
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Affiliation(s)
- Melchor González-Dávila
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Spain.
| | - Maria T Maldonado
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia Vancouver, BC, Canada.
| | - Aridane G González
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Spain.
| | - Jian Guo
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia Vancouver, BC, Canada.
| | - David González-Santana
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Spain.
| | - Antera Martel
- Banco Español de Algas, Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Spain.
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Feng J, Tian L, Wang W, Yang Y, Li Q, Liu L, Bo H, He C. Effect of RSN1 gene knockout on the adsorption of strontium ions by irradiated Saccharomyces cerevisiae. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2024; 273:107396. [PMID: 38325251 DOI: 10.1016/j.jenvrad.2024.107396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 01/27/2024] [Accepted: 02/02/2024] [Indexed: 02/09/2024]
Abstract
The irradiated Saccharomyces cerevisiae (Y-7) has good biosorption ability for strontium ions. To investigate the mechanism of strontium ion bioaccumulation in Y-7, we employed CRISPR/Cas9 gene editing technology to engineer Saccharomyces cerevisiae Y-7 and knock out the RSN1 gene, successfully constructing a RSN1 gene knockout strain (Y-7-rsn1Δ). When tested for strontium ion adsorption, the Y-7-rsn1Δ strain exhibited decreased capacity for adsorbing strontium ions and increased resistance to strontium ions. The results showed that RSN1 is involved in the transport of Sr2+, and observed significant decreases in intracellular Ca2+ of Y-7-rsn1Δ, indicating a strong correlation between bioaccumulation of Sr2+ and Ca2+. This demonstrated that the adsorption of strontium ions by Y-7 is regulated by the RSN1 gene. The knockout of the RSN1 gene resulted in the shift of the peak positions of carboxyl, amino, amide, hydroxyl, and phosphate groups on the cell surface.
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Affiliation(s)
- Jundong Feng
- Department of Materials Science and Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, PR China.
| | - Liuxin Tian
- Department of Materials Science and Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, PR China
| | - Weitai Wang
- Department of Materials Science and Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, PR China
| | - Yingqing Yang
- Department of Materials Science and Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, PR China
| | - Qian Li
- Department of Materials Science and Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, PR China
| | - Liang Liu
- Department of Materials Science and Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, PR China
| | - Hongyu Bo
- Department of Materials Science and Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, PR China
| | - Chengyu He
- Department of Materials Science and Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, PR China
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Tamurejo-Alonso P, González-Martín ML, Pacha-Olivenza MÁ. Electrodeposited Zinc Coatings for Biomedical Application: Morphology, Corrosion and Biological Behaviour. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5985. [PMID: 37687682 PMCID: PMC10488799 DOI: 10.3390/ma16175985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 08/22/2023] [Accepted: 08/28/2023] [Indexed: 09/10/2023]
Abstract
The improvement of biodegradable metals is currently an active and promising research area for their capabilities in implant manufacturing. However, controlling their degradation rate once their surface is in contact with the physiological media is a challenge. Surface treatments are in the way of addressing the improvement of this control. Zinc is a biocompatible metal present in the human body as well as a metal widely used in coatings to prevent corrosion, due to its well-known metal protective action. These two outstanding characteristics make zinc coating worthy of consideration to improve the degradation behaviour of implants. Electrodeposition is one of the most practical and common technologies to create protective zinc coatings on metals. This article aims to review the effect of the different parameters involved in the electrochemical process on the topography and corrosion characteristics of the zinc coating. However, certainly, it also provides an actual and comprehensive description of the state-of-the-art of the use of electrodeposited zinc for biomedical applications, focusing on their capacity to protect against bacterial colonization and to allow cell adhesion and proliferation.
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Affiliation(s)
- Purificación Tamurejo-Alonso
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, University of Extremadura, 06006 Badajoz, Spain;
- University Institute of Extremadura Sanity Research (INUBE), 06006 Badajoz, Spain;
| | - María Luisa González-Martín
- University Institute of Extremadura Sanity Research (INUBE), 06006 Badajoz, Spain;
- Department of Applied Physics, Faculty of Science, University of Extremadura, 06006 Badajoz, Spain
- Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 06006 Badajoz, Spain
| | - Miguel Ángel Pacha-Olivenza
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, University of Extremadura, 06006 Badajoz, Spain;
- University Institute of Extremadura Sanity Research (INUBE), 06006 Badajoz, Spain;
- Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 06006 Badajoz, Spain
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Biofabrication of Functional Pullulan by Aureobasidium pullulans under the Effect of Varying Mineral Salts and Sugar Stress Conditions. Molecules 2023; 28:molecules28062478. [PMID: 36985449 PMCID: PMC10056076 DOI: 10.3390/molecules28062478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 02/18/2023] [Accepted: 02/28/2023] [Indexed: 03/11/2023] Open
Abstract
Pullulan is a linear exopolysaccharide, produced in the fermentation media of Aureobasidium pullulans, with a variety of applications in the food and pharmaceutical industries. Pullulan derivatives have growing potential for biomedical applications, but the high cost of pullulan biofabrication currently restricts its commercial use. Better control over pullulan yield, molecular weight and melanin production by altering fermentation conditions could improve the economics. In this study, the effects of sugar and mineral salt stresses on the pullulan production of A. pullulans ATCC 42023 were examined in batch processes. The chemical structure of the recovered pullulan was characterized by FTIR and NMR spectroscopy, and the molecular weight distribution was obtained via SEC. Pullulan yield and melanin production varied when the conditions were adjusted, and pullulans with different molar masses were obtained. Higher-yield pullulan production and a lower polydispersity index were observed when CuSO4 was added to the fermentation in comparison with the control and with the addition of sugars and other salts. Biofabrication of pullulan under stress conditions is a promising strategy to enhance biopolymer yield and to obtain pullulan with a targeted molecular weight.
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Renteria M, Belkin O, Aickareth J, Jang D, Hawwar M, Zhang J. Zinc's Association with the CmPn/CmP Signaling Network in Breast Cancer Tumorigenesis. Biomolecules 2022; 12:1672. [PMID: 36421686 PMCID: PMC9687477 DOI: 10.3390/biom12111672] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/05/2022] [Accepted: 11/09/2022] [Indexed: 08/24/2023] Open
Abstract
It is well-known that serum and cellular concentrations of zinc are altered in breast cancer patients. Specifically, there are notable zinc hyper-aggregates in breast tumor cells when compared to normal mammary epithelial cells. However, the mechanisms responsible for zinc accumulation and the consequences of zinc dysregulation are poorly understood. In this review, we detailed cellular zinc regulation/dysregulation under the influence of varying levels of sex steroids and breast cancer tumorigenesis to try to better understand the intricate relationship between these factors based on our current understanding of the CmPn/CmP signaling network. We also made some efforts to propose a relationship between zinc signaling and the CmPn/CmP signaling network.
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Affiliation(s)
| | | | | | | | | | - Jun Zhang
- Department of Molecular and Translational Medicine (MTM), Texas Tech University Health Science Center El Paso, El Paso, TX 79905, USA
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Samuelson DR, Haq S, Knoell DL. Divalent Metal Uptake and the Role of ZIP8 in Host Defense Against Pathogens. Front Cell Dev Biol 2022; 10:924820. [PMID: 35832795 PMCID: PMC9273032 DOI: 10.3389/fcell.2022.924820] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 05/26/2022] [Indexed: 01/13/2023] Open
Abstract
Manganese (Mn) and Zinc (Zn) are essential micronutrients whose concentration and location within cells are tightly regulated at the onset of infection. Two families of Zn transporters (ZIPs and ZnTs) are largely responsible for regulation of cytosolic Zn levels and to a certain extent, Mn levels, although much less is known regarding Mn. The capacity of pathogens to persevere also depends on access to micronutrients, yet a fundamental gap in knowledge remains regarding the importance of metal exchange at the host interface, often referred to as nutritional immunity. ZIP8, one of 14 ZIPs, is a pivotal importer of both Zn and Mn, yet much remains to be known. Dietary Zn deficiency is common and commonly occurring polymorphic variants of ZIP8 that decrease cellular metal uptake (Zn and Mn), are associated with increased susceptibility to infection. Strikingly, ZIP8 is the only Zn transporter that is highly induced following bacterial exposure in key immune cells involved with host defense against leading pathogens. We postulate that mobilization of Zn and Mn into key cells orchestrates the innate immune response through regulation of fundamental defense mechanisms that include phagocytosis, signal transduction, and production of soluble host defense factors including cytokines and chemokines. New evidence also suggests that host metal uptake may have long-term consequences by influencing the adaptive immune response. Given that activation of ZIP8 expression by pathogens has been shown to influence parenchymal, myeloid, and lymphoid cells, the impact applies to all mucosal surfaces and tissue compartments that are vulnerable to infection. We also predict that perturbations in metal homeostasis, either genetic- or dietary-induced, has the potential to impact bacterial communities in the host thereby adversely impacting microbiome composition. This review will focus on Zn and Mn transport via ZIP8, and how this vital metal transporter serves as a "go to" conductor of metal uptake that bolsters host defense against pathogens. We will also leverage past studies to underscore areas for future research to better understand the Zn-, Mn- and ZIP8-dependent host response to infection to foster new micronutrient-based intervention strategies to improve our ability to prevent or treat commonly occurring infectious disease.
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Affiliation(s)
- Derrick R. Samuelson
- Division of Pulmonary, Critical Care, and Sleep, Department of Internal Medicine, College of Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Sabah Haq
- Department of Pharmacy Practice and Science, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE, United States
| | - Daren L. Knoell
- Department of Pharmacy Practice and Science, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE, United States,*Correspondence: Daren L. Knoell,
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Cuajungco MP, Ramirez MS, Tolmasky ME. Zinc: Multidimensional Effects on Living Organisms. Biomedicines 2021; 9:biomedicines9020208. [PMID: 33671781 PMCID: PMC7926802 DOI: 10.3390/biomedicines9020208] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/03/2021] [Accepted: 02/09/2021] [Indexed: 12/28/2022] Open
Abstract
Zinc is a redox-inert trace element that is second only to iron in abundance in biological systems. In cells, zinc is typically buffered and bound to metalloproteins, but it may also exist in a labile or chelatable (free ion) form. Zinc plays a critical role in prokaryotes and eukaryotes, ranging from structural to catalytic to replication to demise. This review discusses the influential properties of zinc on various mechanisms of bacterial proliferation and synergistic action as an antimicrobial element. We also touch upon the significance of zinc among eukaryotic cells and how it may modulate their survival and death through its inhibitory or modulatory effect on certain receptors, enzymes, and signaling proteins. A brief discussion on zinc chelators is also presented, and chelating agents may be used with or against zinc to affect therapeutics against human diseases. Overall, the multidimensional effects of zinc in cells attest to the growing number of scientific research that reveal the consequential prominence of this remarkable transition metal in human health and disease.
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Yu XZ, Zhang XH. DNA-protein cross-links involved in growth inhibition of rice seedlings exposed to Ga. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:10830-10838. [PMID: 25772880 DOI: 10.1007/s11356-015-4305-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Accepted: 03/02/2015] [Indexed: 06/04/2023]
Abstract
Hydroponic experiments were conducted with rice seedlings (Oryza sativa L. cv. XZX45) exposed to gallium nitrate (Ga(3+)) to investigate the accumulation of Ga in plant tissues and phytotoxic responses. Results showed that phyto-transport of Ga was apparent, and roots were the dominant site for Ga accumulation. The total accumulation rates of Ga responded biphasically to Ga treatments by showing increases at low (1.06-8.52 mg Ga/L) and constants at high (8.52-15.63 mg Ga/L) concentrations, suggesting that accumulation kinetics of Ga followed a typical saturation curve. Higher amount of Ga accumulation in plant tissues led to significant inhibition in relative growth rate and water use efficiency in a dose-dependent manner. DNA-protein cross-links (DPCs) analysis revealed that overaccumulation of Ga in plant tissues positively stimulated formation of DPCs in roots. Likewise, the measure of root cell viability evaluated by Evan blue uptake showed a similar trend. These results suggested that Ga can be absorbed, transported, and accumulated in plant materials of rice seedlings. Overaccumulation of Ga in plant tissues provoked the formation of DPCs in roots, which resulted in cell death and growth inhibition of rice seedlings.
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Affiliation(s)
- Xiao-Zhang Yu
- The Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, College of Environmental Science & Engineering, Guilin University of Technology, Guilin, 541004, People's Republic of China,
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Tian X, Zheng Y, Li Y, Shen Z, Tao L, Dou X, Qian J, Shen H. Psychological stress induced zinc accumulation and up-regulation of ZIP14 and metallothionein in rat liver. BMC Gastroenterol 2014; 14:32. [PMID: 24548602 PMCID: PMC3931483 DOI: 10.1186/1471-230x-14-32] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 02/13/2014] [Indexed: 12/31/2022] Open
Abstract
Background Zinc is necessary for normal liver function; and vice versa, the liver plays a central role in zinc homeostasis. The aim of present study is to assess the effects of repeated psychological stress (PS) on the zinc metabolism and related mechanism involved in zinc homeostasis in rat liver. Methods In present study, we used communication box to create PS model and investigated the serum corticosterone (CORT), zinc level in serum and liver, liver metallothionein (MT) content and ZRT/IRT-like Protein 14 (ZIP14) mRNA expression. Results The results showed that the serum CORT level increased and serum zinc level decreased significantly after 7 d and 14 d PS treatment. Meanwhile, zinc and MT contents in liver were elevated after 14 d PS exposure, while those in 7 d PS exposure group did not change. ZIP14 mRNA was expressed markedly at 7 d after the onset of PS, while Zip14 mRNA expression in the liver after 14 d PS exposure reached normal level compared with control group. Conclusions The results suggest that PS exposure could induce hypozincemia, which might be related to liver zinc accumulation because of high level of MT through glucocorticoid-mediated MT synthesis and ZIP14 expression induced by interleukin-6.
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Affiliation(s)
| | | | | | | | | | | | - Jianxin Qian
- Department of Naval Hygiene, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, PR China.
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Albarouki E, Deising HB. Infection structure-specific reductive iron assimilation is required for cell wall integrity and full virulence of the maize pathogen Colletotrichum graminicola. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:695-708. [PMID: 23639025 DOI: 10.1094/mpmi-01-13-0003-r] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Ferroxidases are essential components of the high-affinity reductive iron assimilation pathway in fungi. Two ferroxidase genes, FET3-1 and FET3-2, have been identified in the genome of the maize anthracnose fungus Colletotrichum graminicola. Complementation of growth defects of the ferroxidase-deficient Saccharomyces cerevisiae strain Δfet3fet4 showed that both Fet3-1 and Fet3-2 of C. graminicola represent functional ferroxidases. Expression of enhanced green fluorescent protein fusions in yeast and C. graminicola indicated that both ferroxidase proteins localize to the plasma membrane. Transcript abundance of FET3-1 increased dramatically under iron-limiting conditions but those of FET3-2 were hardly detectable. Δfet3-1 and Δfet3-2 single as well as Δfet3-1/2 double-deletion strains were generated. Under iron-sufficient or deficient conditions, vegetative growth rates of these strains did not significantly differ from that of the wild type but Δfet3-1 and Δfet3-1/2 strains showed increased sensitivity to reactive oxygen species. Furthermore, under iron-limiting conditions, appressoria of Δfet3-1 and Δfet3-1/2 strains showed significantly reduced transcript abundance of a class V chitin synthase and exhibited severe cell wall defects. Infection assays on intact and wounded maize leaves, quantitative data of infection structure differentiation, and infection stage-specific expression of FET3-1 showed that reductive iron assimilation is required for appressorial penetration, biotrophic development, and full virulence.
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Affiliation(s)
- Emad Albarouki
- Martin-Luther-Universitat Halle-Wittenberg, Halle, Germany
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12
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Optimized production of Pichia guilliermondii biomass with zinc accumulation by fermentation. Anim Feed Sci Technol 2011. [DOI: 10.1016/j.anifeedsci.2010.09.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Shen H, Qin H, Guo J. Cooperation of metallothionein and zinc transporters for regulating zinc homeostasis in human intestinal Caco-2 cells. Nutr Res 2009; 28:406-13. [PMID: 19083439 DOI: 10.1016/j.nutres.2008.02.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Revised: 12/20/2007] [Accepted: 02/08/2008] [Indexed: 11/15/2022]
Abstract
This investigation examined the effects of zinc status on cell proliferation and the synergic roles of the metallothionein (MT) and zinc transporter (ZnT) in the human colon adenocarcinoma cell line Caco-2. Cells were treated with 0 to 300 micromol/L ZnSO(4) or 0 to 10 micromol/L N,N,N',N'-tetrakis(2-phridylmethyl) ethylenediamine (TPEN). Cell proliferation was determined by MTT assay and apoptotic cells detected by flow cytometry (Hoechst 33258 dye). mRNA expression of MT1; ZnT1; zrt, irt-like protein 1, 4 (ZIP1, 4); and divalent metal transporter (DMT1) were determined by the reverse transcription polymerase chain reaction or real-time polymerase chain reaction. The results showed that either high or low zinc could inhibit the cell proliferation. The number of apoptotic cells increased with incremental increases in the concentrations of ZnSO(4) and TPEN. The mRNA expression of ZnT1 and MT1 responded significantly after 6 and 12 hours with 200 micromol/L zinc treatment, respectively, and increased gradually with zinc levels from 0 to 200 micromol/L. Compared with the unchanged ZIP1 mRNA expression, ZIP4 was closely dependent on TPEN treatment duration and concentration. The DMT1 mRNA expression was upregulated time-dependently but not concentration-dependently in the late TPEN treatment duration. The results suggest that ZIP4 and DMT1 mRNA expressions are susceptible to low extracellular zinc concentration and upregulated to enhance zinc absorption, whereas the ZnT1 and MT1 act as the key regulators under high zinc conditions to enhance the intracellular zinc efflux to maintain zinc homeostasis. We propose that in response to variations in zinc concentration, the cooperated regulative roles of ZnT1, MT1, DMT1, and ZIP4 contribute to zinc homeostasis.
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Affiliation(s)
- Hui Shen
- Department of Military Hygiene, Second Military Medical University, Shanghai 200433, PR China.
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Yu XZ, Gu JD. Uptake, accumulation and metabolic response of ferricyanide in weeping willows. ACTA ACUST UNITED AC 2009; 11:145-52. [DOI: 10.1039/b809304k] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Yu XZ, Gu JD. Effects of available nitrogen on the uptake and assimilation of ferrocyanide and ferricyanide complexes in weeping willows. JOURNAL OF HAZARDOUS MATERIALS 2008; 156:300-307. [PMID: 18249493 DOI: 10.1016/j.jhazmat.2007.12.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Revised: 12/10/2007] [Accepted: 12/10/2007] [Indexed: 05/25/2023]
Abstract
The effects of different levels of external nitrogen on the uptake, distribution and assimilation of iron cyanide complexes were investigated. Pre-rooted weeping willows (Salix babylonica L.) were grown in a hydroponic solution with or without nitrogen and amended with potassium ferrocyanide or potassium ferricyanide at 25.0 +/- 0.5 degrees C for 144 h. Faster uptake of ferrocyanide than ferricyanide was observed in willows grown in the deionized water. Negligible difference in the removal rate between the two chemicals was detected for willows grown in nutrient solutions with or without amendment of nitrogen. The volatilization of ferro- and ferricyanide due to transpiration through plant aerial tissues was below detection level. Less then 20% of the ferrocyanide or ferricyanide taken up from the N-free nutrient solution was recovered in the biomass and majority was accumulated in the roots. In contrast, less than 9.0% of both iron cyanide complexes taken up was detected in the plant materials of willows grown in the N-containing nutrient solution and roots were the major sites for accumulation of both chemicals. A large fraction of the ferro- and ferricyanide taken up from the hydroponic solution was assimilated during the transport within plant materials. Willows grown in the N-containing nutrient solution showed a higher assimilation potential for both chemical forms than those grown in the N-free nutrient solution in general. The information collectively suggests that uptake and assimilation mechanisms for ferro- and ferricyanide are largely different in willows; the strength of external nitrogen had a negligible effect on the uptake of both chemicals, while assimilation of ferro- and ferricyanide in plant materials was strongly related to the presence of easily available nitrogen in the hydroponic solution.
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Affiliation(s)
- Xiao-Zhang Yu
- Laboratory of Environmental Toxicology, School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, PR China
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Yu XZ, Gu JD, Li TP. Availability of ferrocyanide and ferricyanide complexes as a nitrogen source to cyanogenic plants. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2008; 55:229-237. [PMID: 18180862 DOI: 10.1007/s00244-007-9101-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 11/22/2007] [Indexed: 05/25/2023]
Abstract
The effects of additional nitrogen on the toxicity and removal of ferrocyanide and ferricyanide by cyanogenic plants were investigated. Maize (Zea mays L. var. ZN 304) seedlings were grown in the hydroponic solutions with or without additional nitrogen, and amended with either potassium ferrocyanide or potassium ferricyanide at 25.0 +/- 0.5 degrees C for 144 h. Various physiological parameters were monitored to determine the responses of the plant seedlings to the exposure of these two chemicals. A remarkable decrease in transpiration rate, biomass, shoot length, chlorophyll contents, and soluble proteins was evident for maize seedlings grown in the N-free hydroponic solutions spiked with either ferrocyanide or ferricyanide (P < 0.01), but slight changes were observed in the selective parameters in the N-containing hydroponic solutions spiked with either of these chemicals (P > 0.05). A higher removal of ferrocyanide than ferricyanide was registered in the N-free hydroponic solutions, but more ferricyanide than ferrocyanide was removed by maize grown in the N-containing nutrient solutions (P < 0.01). Although roots of maize accumulated iron cyanides, more cyanide was recovered in plant materials of those grown in the N-containing hydroponic solutions than the N-free nutrient solutions (P < 0.05). Mass balance analysis indicated that the majority of the iron cyanides removed from solution was assimilated by maize and additional nitrogen had a significantly negative impact on the uptake of both chemicals (P < 0.01). Results of this study suggest that uptake and assimilation mechanisms for ferrocyanide and ferricyanide might be quite different in maize and the application of the external nitrogen has a substantial influence on the removal of both iron cyanides by plants. None of the iron cyanide complexes can serve as a sole nitrogen source to support maize growth.
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Affiliation(s)
- Xiao-Zhang Yu
- Laboratory of Environmental Toxicology, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, People's Republic of China
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17
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Haas H, Eisendle M, Turgeon BG. Siderophores in fungal physiology and virulence. ANNUAL REVIEW OF PHYTOPATHOLOGY 2008; 46:149-87. [PMID: 18680426 DOI: 10.1146/annurev.phyto.45.062806.094338] [Citation(s) in RCA: 302] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Maintaining the appropriate balance of iron between deficiency and toxicity requires fine-tuned control of systems for iron uptake and storage. Both among fungal species and within a single species, different systems for acquisition, storage, and regulation of iron are present. Here we discuss the most recent findings on the mechanisms involved in maintaining iron homeostasis with a focus on siderophores, low-molecular-mass iron chelators, employed for iron uptake and storage. Recently siderophores have been found to be crucial for pathogenicity of animal, as well as plant-pathogenic fungi and for maintenance of plant-fungal symbioses.
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Affiliation(s)
- Hubertus Haas
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, A-6020 Innsbruck, Austria.
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18
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Shen H, Zhang Y, Xu J, Long J, Qin H, Liu F, Guo J. Zinc distribution and expression pattern of ZnT3 in mouse brain. Biol Trace Elem Res 2007; 119:166-74. [PMID: 17916939 DOI: 10.1007/s12011-007-0056-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 04/09/2007] [Accepted: 05/03/2007] [Indexed: 11/26/2022]
Abstract
To explore the relationship between the zinc distribution and zinc transporter 3 (ZnT3) mRNA expression in the mouse brain, zinc contents and its distribution were determined by synchrotron radiation x-ray fluorescence (SRXRF), and ZnT3 mRNA expression was examined by reverse-transcription polymerase chain reaction and in situ hybridization. The results showed that the zinc contents were not distributed evenly in various brain tissues. The zinc contents in cerebral cortex and hippocampus were nearly 5-10 times higher than that in other neural locations. Correspondingly, ZnT3 mRNA expression was observed in high abundance in the cerebral cortex, hippocampus, and testis, but was not detected in other organs and tissues. In the nervous system, ZnT3 mRNA was detected mainly in hippocampus, cerebral cortex, and spinal ganglion. The present results show the coincident distribution of zinc and ZnT3 mRNA in mouse brain. The high zinc contents might be determined by the high expression of ZnT3. More meaningfully, the results showed the feasibility of applying of SRXRF in examining the distribution of minerals in different organs and tissues. In addition, it was observed for the first time that ZnT3 mRNA was expressed in the facial nucleus. The function of ZnT3 in facial nucleus awaits further study.
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Affiliation(s)
- Hui Shen
- Department of Military Hygiene, Second Military Medical University, Shanghai 200433, China.
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19
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Wang J, Chen C. Biosorption of heavy metals by Saccharomyces cerevisiae: A review. Biotechnol Adv 2006; 24:427-51. [PMID: 16737792 DOI: 10.1016/j.biotechadv.2006.03.001] [Citation(s) in RCA: 513] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2006] [Indexed: 11/26/2022]
Abstract
Heavy metal pollution has become one of the most serious environmental problems today. Biosorption, using biomaterials such as bacteria, fungi, yeast and algae, is regarded as a cost-effective biotechnology for the treatment of high volume and low concentration complex wastewaters containing heavy metal(s) in the order of 1 to 100 mg/L. Among the promising biosorbents for heavy metal removal which have been researched during the past decades, Saccharomyces cerevisiae has received increasing attention due to the unique nature in spite of its mediocre capacity for metal uptake compared with other fungi. S. cerevisiae is widely used in food and beverage production, is easily cultivated using cheap media, is also a by-product in large quantity as a waste of the fermentation industry, and is easily manipulated at molecular level. The state of the art in the field of biosorption of heavy metals by S. cerevisiae not only in China, but also worldwide, is reviewed in this paper, based on a substantial number of relevant references published recently on the background of biosorption achievements and development. Characteristics of S. cerevisiae in heavy metal biosorption are extensively discussed. The yeast can be studied in various forms for different purposes. Metal-binding capacity for various heavy metals by S. cerevisiae under different conditions is compared. Lead and uranium, for instances, could be removed from dilute solutions more effectively in comparison with other metals. The yeast biosorption largely depends on parameters such as pH, the ratio of the initial metal ion and initial biomass concentration, culture conditions, presence of various ligands and competitive metal ions in solution and to a limited extent on temperature. An assessment of the isotherm equilibrium model, as well as kinetics was performed. The mechanisms of biosorption are understood only to a limited extent. Elucidation of the mechanism of metal uptake is a real challenge in the field of biosorption. Various mechanism assumptions of metal uptake by S. cerevisiae are summarized.
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Affiliation(s)
- Jianlong Wang
- Laboratory of Environmental Technology, INET, Tsinghua University, Beijing 100084, PR China
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20
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Kumánovics A, Poruk KE, Osborn KA, Ward DM, Kaplan J. YKE4 (YIL023C) Encodes a Bidirectional Zinc Transporter in the Endoplasmic Reticulum of Saccharomyces cerevisiae. J Biol Chem 2006; 281:22566-74. [PMID: 16760462 DOI: 10.1074/jbc.m604730200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
YIL023C encodes a member of the SLC39A, or ZIP, family, which we refer to as yeast KE4 (YKE4) after its mouse ortholog. Yke4p was localized to the endoplasmic reticulum (ER) membrane using Yke4p-specific antiserum. YKE4 is not an essential gene; however, deletion of YKE4 resulted in a sensitivity to calcofluor white and poor growth at 36 degrees C on respiratory substrates containing high zinc. Overexpression of transition metal transporters Zrc1p and Cot1p or the mouse orthologue mKe4 in Deltayke4 suppressed the poor growth at 36 degrees C on respiratory substrates. We found that the role of Yke4p depends on the zinc status of the cells. In a zinc-adequate environment, Yke4p transports zinc into the secretory pathway, and the deletion of YKE4 leads to a zinc-suppressible cell wall defect. In high zinc medium, transport of zinc into the secretory pathway through Yke4p is a way to eliminate zinc from the cytosol, and deletion of YKE4 leads to toxic zinc accumulation in the cytosol. Under low cytosolic zinc conditions, however, Yke4p removes zinc from the secretory pathway, and deletion of YKE4 partially compensates for the loss of Msc2p, an ER zinc importer, and therefore helps to alleviate ER stress. In our model, Yke4p balances zinc levels between the cytosol and the secretory pathway, whereas the previously described Msc2p-Zrg17p ER zinc importer complex functions mainly in zinc-depleted conditions to ensure a ready supply of zinc essential for ER functions, such as phospholipid biosynthesis and unfolded protein response.
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Affiliation(s)
- Attila Kumánovics
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA
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21
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Arnesano F, Banci L, Bertini I, Capozzi F, Ciofi-Baffoni S, Ciurli S, Luchinat C, Mangani S, Rosato A, Turano P, Viezzoli MS. An Italian contribution to structural genomics: Understanding metalloproteins. Coord Chem Rev 2006. [DOI: 10.1016/j.ccr.2006.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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22
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Nevo Y, Nelson N. The NRAMP family of metal-ion transporters. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:609-20. [PMID: 16908340 DOI: 10.1016/j.bbamcr.2006.05.007] [Citation(s) in RCA: 278] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 05/08/2006] [Accepted: 05/10/2006] [Indexed: 12/16/2022]
Abstract
The family of NRAMP metal ion transporters functions in diverse organisms from bacteria to human. NRAMP1 functions in metal transport across the phagosomal membrane of macrophages, and defective NRAMP1 causes sensitivity to several intracellular pathogens. DCT1 (NRAMP2) transport metal ions at the plasma membrane of cells of both the duodenum and in peripheral tissues, and defective DCT1 cause anemia. The driving force for the metal-ion transport is proton gradient (protonmotive force). In DCT1 the stoichiometry between metal ion and proton varied at different conditions due to a mechanistic proton slip. Though the metal ion transport by Smf1p, the yeast homolog of DCT1, is also a protonmotive force, a slippage of sodium ions was observed. The mechanism of the above phenomena could be explained by a combination between transporter and channel mechanisms.
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Affiliation(s)
- Yaniv Nevo
- Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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23
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Larsen M, Trapp S. Uptake of iron cyanide complexes into willow trees. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2006; 40:1956-61. [PMID: 16570621 DOI: 10.1021/es051224q] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The uptake of iron cyanide into willows was studied. Trees were grown in solutions with Prussian blue, ferricyanide, or ferrocyanide. Iron cyanide speciation in solution was determined by HPLC during the experiment. Total cyanide and total iron in solution and trees were measured at the end of the experiments. Ferrocyanide wasthe dominating species in most solutions at the end. Ferricyanide was preferably taken up from solutions. Between 20 and 83% of the cyanide was lost from the solutions, and up to 28% could be recovered from the plants, mainly from roots. Cyanide could also be detected in stems and leaves of most exposed trees. Uptake was increased when no other nitrogen source but cyanide was present in solutions. Iron contents in exposed trees, compared to controls, increased significantly. The ratio of iron to cyanide remained rather stable in solution, but changed to higher values inside the plants. This indicates that iron and cyanide were taken up together as a complex, which was dissolved inside plants, and then cyanide was metabolized. No toxic effects could be seen. The study shows that trees can take up and metabolize iron cyanide complexes, making phytoremediation of iron cyanide waste a feasible option.
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Affiliation(s)
- Morten Larsen
- Institute of Environment and Resources, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
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24
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Tuszynska S, Davies D, Turnau K, Ashford AE. Changes in vacuolar and mitochondrial motility and tubularity in response to zinc in a Paxillus involutus isolate from a zinc-rich soil. Fungal Genet Biol 2006; 43:155-63. [PMID: 16504552 DOI: 10.1016/j.fgb.2005.11.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Revised: 11/04/2005] [Accepted: 11/10/2005] [Indexed: 11/26/2022]
Abstract
Short-term effects of zinc on organelles were investigated in Paxillus involutus from a zinc-rich soil. Vacuoles were labelled with Oregon Green 488 carboxylic acid and mitochondria with DiOC(6)(3). Hyphae were treated with ZnSO(4) in the range 1-100 mM and examined by fluorescence microscopy. ZnSO(4) caused loss of tubularity and motility in both organelles depending on concentration and exposure time. Tubular vacuoles thickened after 15 min in 5 mM ZnSO(4) and became spherical at higher concentrations. Mitochondria fragmented after 30 min in 25 mM ZnSO(4). Vacuoles recovered their tubularity after transfer to reverse osmosis water depending on ZnSO(4) concentration and exposure time during treatment. Mitochondria recovered their tubularity with time, both with and without removal of the ZnSO(4) solution. K(2)SO(4) (as control) had no effect on vacuoles but disrupted mitochondria, the effect also depending on concentration and duration of exposure.
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Affiliation(s)
- Sandra Tuszynska
- School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, Australia.
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25
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Dufner-Beattie J, Huang ZL, Geiser J, Xu W, Andrews GK. Generation and characterization of mice lacking the zinc uptake transporter ZIP3. Mol Cell Biol 2005; 25:5607-15. [PMID: 15964816 PMCID: PMC1156975 DOI: 10.1128/mcb.25.13.5607-5615.2005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mouse ZIP3 (SLC39A3) gene encodes an eight-transmembrane-domain protein that has been conserved in mammals and can function to transport zinc. To analyze the expression of ZIP3 in the early embryo and neonate and to determine its in vivo function, we generated ZIP3 null mice in which the ZIP3 open reading frame was replaced with that of the enhanced green fluorescent protein (EGFP) reporter. EGFP fluorescence revealed that ZIP3 was expressed in the inner cell mass of the blastocyst and later during embryonic development in many tissues. Elevated expression was apparent in the embryonic brain and neurotube and neonatal gonads. Homozygous knockout mice were viable and fertile and under normal growth conditions exhibited no obvious phenotypic abnormalities. Deletion of ZIP3 did not alter zinc homeostasis at the molecular level as assessed by essential metal levels and the expression of zinc-responsive genes. In knockout mice stressed with a zinc-deficient diet during pregnancy or at weaning, a subtle increase in the sensitivity to abnormal morphogenesis of the embryo and to depletion of thymic pre-T cells, respectively, was noted. These results suggest that this protein plays an ancillary role in zinc homeostasis in mice.
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Affiliation(s)
- Jodi Dufner-Beattie
- Department of Biochemistry and Molecular Biology, Mail Stop 3030, University of Kansas Medical Center, 39th and Rainbow Blvd., Kansas City, Kansas 66160-7421, USA
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26
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Aravind P, Prasad MNV. Cadmium-Zinc interactions in a hydroponic system using Ceratophyllum demersum L.: adaptive ecophysiology, biochemistry and molecular toxicology. ACTA ACUST UNITED AC 2005. [DOI: 10.1590/s1677-04202005000100002] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interaction between an essential micronutrient, Zn and a toxic non-essential element, Cd has been comprehensively reviewed based on our experiments conducted with Ceratophyllum demersum L. in a hydroponic system. Since Cd and Zn belong to the group IIB transition elements and show similarities in chemistry, geochemistry and environmental properties, it would be one of the elemental pairs of choice to investigate metal-metal interactions. Evidence in support of the protective role of Zn against Cd toxicity in Ceratophyllum demersum L. is presented in this review. Based on our experimental results, we conclude that the antioxidant properties of Zn play an important role in counteracting Cd toxicity.
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27
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Dufner-Beattie J, Kuo YM, Gitschier J, Andrews GK. The adaptive response to dietary zinc in mice involves the differential cellular localization and zinc regulation of the zinc transporters ZIP4 and ZIP5. J Biol Chem 2004; 279:49082-90. [PMID: 15358787 DOI: 10.1074/jbc.m409962200] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ZIP5 gene encodes a protein closely related to ZIP4, a zinc transporter mutated in the human genetic disorder acrodermatitis enteropathica. Herein, we demonstrate that mouse ZIP5 and ZIP4 genes are co-expressed in several tissues involved in zinc homeostasis (intestine, pancreas, embryonic yolk sac). However, unlike expression of the ZIP4 gene, which is induced during periods of zinc deficiency, ZIP5 gene expression is unaltered by dietary zinc. Immunohistochemistry localizes ZIP5 to the basolateral surfaces of enterocytes, acinar cells, and visceral endoderm cells in mice fed a zinc-adequate diet. However, this protein is removed from these cell surfaces and internalized during dietary zinc deficiency. In contrast, ZIP4 is induced and recruited to the apical surface of enterocytes and endoderm cells during zinc deficiency. In the pancreas, ZIP4 is expressed in beta-cells, whereas ZIP5 is expressed in acinar cells. These results suggest that the function of ZIP5 is antagonistic to that of ZIP4 in the control of zinc homeostasis; rather than functioning in the acquisition of dietary zinc, as does ZIP4, ZIP5 may function in the removal of zinc from the body. Thus, during periods when dietary zinc is replete, ZIP5 may function to remove zinc from the blood via the pancreas and intestine, the major sites of zinc excretion in mammals, whereas the acquisition of dietary zinc by intestinal ZIP4 would be minimal. In contrast, during periods of dietary zinc deficiency when secretion of zinc by the pancreas and intestine is minimized, ZIP5 is removed from the cell surface, and the intestinal uptake of zinc is augmented by induction of ZIP4.
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Affiliation(s)
- Jodi Dufner-Beattie
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160-7421, USA
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28
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Roberts LA, Pierson AJ, Panaviene Z, Walker EL. Yellow stripe1. Expanded roles for the maize iron-phytosiderophore transporter. PLANT PHYSIOLOGY 2004; 135:112-20. [PMID: 15107503 PMCID: PMC429338 DOI: 10.1104/pp.103.037572] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Revised: 01/13/2004] [Accepted: 02/25/2004] [Indexed: 05/18/2023]
Abstract
Graminaceous monocots, including most of the world's staple grains (i.e. rice, corn, and wheat) use a chelation strategy (Strategy II) for primary acquisition of iron from the soil. Strategy II plants secrete phytosiderophores (PS), compounds of the mugineic acid family that form stable Fe(III) chelates in soil. Uptake of iron-PS chelates, which occurs through specific transporters at the root surface, thus represents the primary route of iron entry into Strategy II plants. The gene Yellow stripe1 (Ys1) encodes the Fe(III)-PS transporter of maize (Zea mays). Here the physiological functions performed by maize YS1 were further defined by examining the pattern of Ys1 mRNA and protein accumulation and by defining YS1 transport specificity in detail. YS1 is able to translocate iron that is bound either by PS or by the related compound, nicotianamine; thus, the role of YS1 may be to transport either of these complexes. Ys1 expression at both the mRNA and protein levels responds rapidly to changes in iron availability but is not strongly affected by limitation of copper or zinc. Our data provide no support for the idea that YS1 is a transporter of zinc-PS, based on YS1 biochemical activity and Ys1 mRNA expression patterns in response to zinc deficiency. YS1 is capable of transporting copper-PS, but expression data suggest that the copper-PS uptake has limited significance in primary uptake of copper.
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Affiliation(s)
- Louis A Roberts
- Biology Department, University of Massachusetts, Amherst, Massachusetts 01003, USA
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29
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Banci L, Bertini I, Ciofi-Baffoni S, Gonnelli L, Su XC. Structural Basis for the Function of the N-terminal Domain of the ATPase CopA from Bacillus subtilis. J Biol Chem 2003; 278:50506-13. [PMID: 14514665 DOI: 10.1074/jbc.m307389200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The solution structure of the N-terminal region (151 amino acids) of a copper ATPase, CopA, from Bacillus subtilis, is reported here. It consists of two domains, CopAa and CopAb, linked by two amino acids. It is found that the two domains, which had already been separately characterized, interact one to the other through a hydrogen bond network and a few hydrophobic interactions, forming a single rigid body. The two metal binding sites are far from one another, and the short link between the domains prevents them from interacting. This and the surface electrostatic potential suggest that each domain receives copper from the copper chaperone, CopZ, independently and transfers it to the membrane binding site of CopA. The affinity constants of silver(I) and copper(I) are similar for the two sites as monitored by NMR. Because the present construct "domain-short link-domain" is shared also by the last two domains of the eukaryotic copper ATPases and several residues at the interface between the two domains are conserved, the conclusions of the present study have general validity for the understanding of the function of copper ATPases.
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Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center CERM and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy
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30
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Dufner-Beattie J, Langmade SJ, Wang F, Eide D, Andrews GK. Structure, function, and regulation of a subfamily of mouse zinc transporter genes. J Biol Chem 2003; 278:50142-50. [PMID: 14525987 DOI: 10.1074/jbc.m304163200] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Zinc is an essential metal for all eukaryotes, and cells have evolved a complex system of proteins to maintain the precise balance of zinc uptake, intracellular storage, and efflux. In mammals, zinc uptake appears to be mediated by members of the Zrt/Irt-like protein (ZIP) superfamily of metal ion transporters. Herein, we have studied a subfamily of zip genes (zip1, zip2, and zip3) that is conserved in mice and humans. These eight-transmembrane domain proteins contain a conserved 12-amino acid signature sequence within the fourth transmembrane domain. All three of these mouse ZIP proteins function to specifically increase the uptake of zinc in transfected cultured cells, similar to the previously demonstrated functions of human ZIP1 and ZIP2 (Gaither, L. A., and Eide, D. J. (2000) J. Biol. Chem. 275, 5560-5564; Gaither, L. A., and Eide, D. J. (2001) J. Biol. Chem. 276, 22258-22264). No ZIP3 orthologs have been previously studied. Furthermore, this first systematic comparative study of the in vivo expression and dietary zinc regulation of this subfamily of zip genes revealed that 1) zip1 mRNA is abundant in many mouse tissues, whereas zip2 and zip3 mRNAs are very rare or moderately rare, respectively, and tissue-restricted in their accumulation; and 2) unlike mouse metallothionein I and zip4 mRNAs (Dufner-Beattie, J., Wang, F., Kuo, Y.-M., Gitschier, J., Eide, D., and Andrews, G. K. (2003) J. Biol. Chem. 278, 33474-33481), the abundance of zip1, zip2, and zip3 mRNAs is not regulated by dietary zinc in the intestine and visceral endoderm, tissues involved in nutrient absorption. These studies suggest that all three of these ZIP proteins may play cell-specific roles in zinc homeostasis rather than primary roles in the acquisition of dietary zinc.
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Affiliation(s)
- Jodi Dufner-Beattie
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160-7421, USA
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31
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Urani C, Calini V, Melchioretto P, Morazzoni F, Canevali C, Camatini M. Different induction of metallothioneins and Hsp70 and presence of the membrane transporter ZnT-1 in HepG2 cells exposed to copper and zinc. Toxicol In Vitro 2003; 17:553-9. [PMID: 14599444 DOI: 10.1016/s0887-2333(03)00117-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Eukaryotic cells respond to stressful environmental stimuli, such as toxic concentrations of heavy metals, by rapidly synthesising defence proteins: the metallothioneins (MT) and the heat shock protein 70 (Hsp70). In this study we have analysed how the human hepatoblastoma cell line HepG2 responds to exposure to excess copper (30 microg/ml) and zinc (50 microg/ml) for long exposure times (48 and 72 h). Accumulation of the two metals, as measured by ICP-AES, was time-dependent reaching a plateau after 72 h. HepG2 cells responded by dramatically increasing levels of MT during stress, mostly during zinc exposure. A time lag in Hsp70 induction was observed as the levels of this protein increased only after removal of the stress from culture medium (recovery) for 24 h, thus suggesting that the two defence mechanisms are not coordinated in a metal-induced stress response. Moreover in HepG2 cells, immunochemical and fluorescence techniques showed the presence and the localisation of the zinc membrane exporter ZnT-1 as a further mechanism of defence/homeostasis against zinc toxicity.
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Affiliation(s)
- C Urani
- Dipartimento di Scienze dell'Ambiente e del Territorio, Università degli Studi di Milano Bicocca, p.zza della Scienza 1, 20126 Milan, Italy.
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Dufner-Beattie J, Wang F, Kuo YM, Gitschier J, Eide D, Andrews GK. The acrodermatitis enteropathica gene ZIP4 encodes a tissue-specific, zinc-regulated zinc transporter in mice. J Biol Chem 2003; 278:33474-81. [PMID: 12801924 DOI: 10.1074/jbc.m305000200] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human ZIP4 gene (SLC39A4) is a candidate for the genetic disorder of zinc metabolism acrodermatitis enteropathica. To understand its role in zinc homeostasis, we examined the function and expression of mouse ZIP4. This gene encodes a well conserved eight-transmembrane protein that can specifically increase the influx of zinc into transfected cells. Expression of this gene is robust in tissues involved in nutrient uptake, such as the intestines and embryonic visceral yolk sac, and is dynamically regulated by zinc. Dietary zinc deficiency causes a marked increase in the accumulation of ZIP4 mRNA in these tissues, whereas injection of zinc or increasing zinc content of the diet rapidly reduces its abundance. Zinc can also regulate the accumulation of ZIP4 protein at the apical surface of enterocytes and visceral endoderm cells. These results provide compelling evidence that ZIP4 is a zinc transporter that plays an important role in zinc homeostasis, a process that is defective in acrodermatitis enteropathica in humans.
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Affiliation(s)
- Jodi Dufner-Beattie
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160-7421, USA
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Abstract
It is difficult to over-state the importance of Zn(II) in biology. It is a ubiquitous essential metal ion and plays a role in catalysis, protein structure and perhaps as a signal molecule, in organisms from all three kingdoms. Of necessity, organisms have evolved to optimise the intracellular availability of Zn(II) despite the extracellular milieu. To this end, prokaryotes contain a range of Zn(II) import, Zn(II) export and/or binding proteins, some of which utilise either ATP or the chemiosmotic potential to drive the movement of Zn(II) across the cytosolic membrane, together with proteins that facilitate the diffusion of this ion across either the outer or inner membranes of prokaryotes. This review seeks to give an overview of the systems currently classified as altering Zn(II) availability in prokaryotes.
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Affiliation(s)
- Dayle K Blencowe
- Cardiff School of Biosciences (2), Cardiff University, Museum Avenue, P.O. Box 911, Cardiff CF10 3US, Wales, UK
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Wartmann T, Stephan UW, Bube I, Böer E, Melzer M, Manteuffel R, Stoltenburg R, Guengerich L, Gellissen G, Kunze G. Post-translational modifications of the AFET3 gene product: a component of the iron transport system in budding cells and mycelia of the yeast Arxula adeninivorans. Yeast 2002; 19:849-62. [PMID: 12112239 DOI: 10.1002/yea.880] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The yeast Arxula adeninivorans is characterized by a temperature-dependent dimorphism. A. adeninivorans grows as budding cells at temperatures up to 42 degrees C, but forms mycelia at higher temperatures. A strong correlation exists between morphological status and iron uptake, achieved by two transport systems that differ in iron affinity. In the presence of high Fe(II) concentrations (>2 microm), budding cells accumulate iron concentrations up to seven-fold higher than those observed in mycelia, while at low Fe(II) concentrations (<2 microm), both cell types accumulate similar amounts of iron. The copper-dependent Fe(II) oxidase Afet3p, composed of 615 amino acids, is a component of the high-affinity iron transport system. This protein shares a high degree of homology with other yeast iron transport proteins, namely Fet3p of Saccharomyces cerevisiae, Cafet3p of Candida albicans and Pfet3p of Pichia pastoris. Expression of the AFET3 gene is found to be strongly dependent on iron concentration but independent of the morphological stage; however, cell morphology was found to influence post-translational modifications of the gene product. O-glycosylation was observed in budding cells only, whereas N-glycosylation occurred in both cell types. The N-glycosylated 103 kDa glycoprotein matures into the 108.5 kDa form, further characterized by serine phosphorylation. Both N-glycosylation and phosphorylation occur at low iron concentrations (< or =5 microm). The mature Afet3p of 108.5 kDa is uniformly distributed within the plasma membrane in cells of both morphological stages.
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Affiliation(s)
- Thomas Wartmann
- Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany.
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35
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Kambe T, Narita H, Yamaguchi-Iwai Y, Hirose J, Amano T, Sugiura N, Sasaki R, Mori K, Iwanaga T, Nagao M. Cloning and characterization of a novel mammalian zinc transporter, zinc transporter 5, abundantly expressed in pancreatic beta cells. J Biol Chem 2002; 277:19049-55. [PMID: 11904301 DOI: 10.1074/jbc.m200910200] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intracellular homeostasis for zinc is achieved through the coordinate regulation of specific transporters engaged in zinc influx, efflux, and intracellular compartmentalization. We have identified a novel mammalian zinc transporter, zinc transporter 5 (ZnT-5), by virtue of its similarity to ZRC1, a zinc transporter of Saccharomyces cerevisiae, a member of the cation diffusion facilitator family. Human ZnT-5 (hZnT-5) cDNA encodes a 765-amino acid protein with 15 predicted membrane-spanning domains. hZnT-5 was ubiquitously expressed in all tested human tissues and abundantly expressed in the pancreas. In the human pancreas, hZnT-5 was expressed abundantly in insulin-containing beta cells that contain zinc at the highest level in the body. The hZnT-5 immunoreactivity was found to be associated with secretory granules by electron microscopy. The hZnT-5-derived zinc transport activity was detected using the Golgi-enriched vesicles prepared from hZnT-5-induced HeLa/hZnT-5 cells in which exogenous hZnT-5 expression is inducible by the Tet-on gene regulation system. This activity was dependent on time, temperature, and concentration and was saturable. Moreover, zinc at a high concentration (10 mm) inhibited the growth of yeast expressing hZnT-5. These results suggest that ZnT-5 plays an important role for transporting zinc into secretory granules in pancreatic beta cells.
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Affiliation(s)
- Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
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36
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Colvin RA. pH dependence and compartmentalization of zinc transported across plasma membrane of rat cortical neurons. Am J Physiol Cell Physiol 2002; 282:C317-29. [PMID: 11788343 DOI: 10.1152/ajpcell.00143.2001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, Zn(2+) transport in rat cortical neurons was characterized by successfully combining radioactive tracer experiments with spectrofluorometry and fluorescence microscopy. Cortical neurons showed a time-dependent and saturable transport of (65)Zn(2+) with an apparent affinity of 15-20 microM. (65)Zn(2+) transport was pH dependent and was decreased by extracellular acidification and increased by intracellular acidification. Compartmentalization of newly transported Zn(2+) was assessed with the Zn(2+)-selective fluorescent dye zinquin. Resting cortical neurons showed uniform punctate labeling that was found in cell processes and the soma, suggesting extrasynaptic compartmentalization of Zn(2+). Depletion of intracellular Zn(2+) with the membrane-permeant chelator N,N,N',N'-tetrakis(2-pyridylmethyl)-ethylenediamine (TPEN) resulted in the complete loss of punctate zinquin labeling. After Zn(2+) depletion, punctate zinquin labeling was rapidly restored when cells were placed in 30 microM Zn(2+), pH 7.4. However, rapid restoration of punctate zinquin labeling was not observed when cells were placed in 30 microM Zn(2+), pH 6.0. These data were confirmed in parallel (65)Zn(2+) transport experiments.
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Affiliation(s)
- Robert A Colvin
- Program in Neuroscience, Department of Biological Sciences, Ohio University, Athens, Ohio 45701, USA.
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37
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Urani C, Melchioretto P, Morazzoni F, Canevali C, Camatini M. Copper and zinc uptake and hsp70 expression in HepG2 cells. Toxicol In Vitro 2001; 15:497-502. [PMID: 11566583 DOI: 10.1016/s0887-2333(01)00054-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of this work is to study the accumulation in HepG2 cells of two essential metals with toxic potency and to analyse the induction of the heat shock protein 70 kDa (hsp70) consequent to metal exposure. Cu and Zn were the metals considered and were analysed both as single compounds and in combination in order to evidence synergic effects of the mixture. The use of HepG2 cells provided an in vitro system that retains morphological and metabolic properties and the expression of specific genes typical of liver parenchymal cells. Moreover, the hepatic cells represent a suitable model for their susceptibility to metal toxicity since liver, gastrointestinal tract and renal tubular cells are involved in the uptake, transport, detoxification and secretion of these compounds. The uptake of Cu and Zn followed a time-dependent accumulation when they were used separate. The combination of the two metals produced a higher accumulation of Zn. The stress protein hsp70 was expressed before the metals accumulated within the cells, as shown by the measures obtained with the ICP-AES technique. Moreover, the accumulation of hsp70 by a sublethal shock provided a protective mechanism against metal cytotoxicity.
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Affiliation(s)
- C Urani
- Dipartimento di Scienze dell'Ambiente e del Territorio, Università degli Studi di Milano Bicocca, p.zza della Scienza 1, 20126 Milan, Italy
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38
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Zhai Q, Ji H, Zheng Z, Sun L, Liu X. Investigating the function of Akt by tet-off inducible expression system. CHINESE SCIENCE BULLETIN-CHINESE 2001. [DOI: 10.1007/bf03187173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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39
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Abstract
The biochemistry of human nutritional zinc deficiency remains poorly defined. To characterize in genetic terms how cells respond to zinc deprivation, zinc-regulated genes (ZRG's) were identified in yeast. Gene expression was probed using random lacZ reporter gene fusions, integrated by transposon tagging into a diploid genome as previously described. About half of the genome was examined. Cells exhibiting differences in lacZ expression on low or moderate ( approximately 0. 1 vs. 10 microm) zinc media were isolated and the gene fusions were sequenced. Ribonuclease protection assays demonstrated four- to eightfold increases for the RNAs of the ZAP1, ZRG17 (YNR039c), DPP1, ADH4, MCD4, and YEF3B genes in zinc-deficient cells. All but YEF3B were shown through reporter gene assays to be controlled by a master regulator of zinc homeostasis now known to be encoded by ZAP1. ZAP1 mutants lacked the flocculence and distended vacuoles characteristic of zinc-deficient cells, suggesting that flocculation and vacuolation serve homeostatic functions in zinc-deficient cells. ZRG17 mutants required extra zinc supplementation to repress these phenotypes, suggesting that ZRG17 functions in zinc uptake. These findings illustrate the utility of transposon tagging as an approach for studying regulated gene expression in yeast.
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Affiliation(s)
- D S Yuan
- Division of Pediatric Gastroenterology and Nutrition, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-2631, USA.
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40
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López LB, Braga MB, López JO, Arroyo R, Costa e Silva Filho F. Strategies by which some pathogenic trichomonads integrate diverse signals in the decision-making process. AN ACAD BRAS CIENC 2000; 72:173-86. [PMID: 10932116 DOI: 10.1590/s0001-37652000000200006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The interaction between each one of Trichomonas vaginalis and Tritrichomonas foetus with their hosts is a complex process in which components associated to the cell surfaces of both parasites and host epithelial cells, and also to soluble components found in vaginal/urethral secretions, are involved. Either cytoadhesion or the cytotoxicity exerted by parasites to host cells can be dictated by virulence factors such as adhesins, cysteine proteinases, laminin-binding proteins, integrins, integrin-like molecules, a cell detachment factor, a pore-forming protein, and glycosidases among others. How trichomonads manipulate informations from the extracellular medium, transduce such informations, and respond to them by stimulating the activities of some surface molecules and/or releasing enzymes are the aspects concerning trichomonal virulence which are here briefly reviewed and discussed.
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Affiliation(s)
- L B López
- UFRJ-Instituto de Biofísica Carlos Chagas Filho, Rio de Janeiro, Brazil
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41
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Chiang KT, Shinyashiki M, Switzer CH, Valentine JS, Gralla EB, Thiele DJ, Fukuto JM. Effects of nitric oxide on the copper-responsive transcription factor Ace1 in Saccharomyces cerevisiae: cytotoxic and cytoprotective actions of nitric oxide. Arch Biochem Biophys 2000; 377:296-303. [PMID: 10845707 DOI: 10.1006/abbi.2000.1785] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies indicate that nitric oxide (NO) can serve as a regulator/disrupter of metal-metabolizing systems in cells and, indeed, this function may represent an important physiological and/or pathophysiological role for NO. In order to address possible mechanisms of this aspect of NO biology, the effect of NO on copper metabolism and toxicity in the yeast Saccharomyces cerevisiae was examined. Exposure of S. cerevisiae to NO resulted in an alteration of the activity of the copper-responsive transcription factor Acel. Low concentrations of the NO donor DEA/NO were found to slightly enhance copper-mediated activation of Acel. Since Acel regulates the expression of genes responsible for the protection of S. cerevisiae from metal toxicity, the effect of NO on the toxicity of copper toward S. cerevisiae was also examined. Interestingly, low concentrations of NO were also found to protect S. cerevisiae against the toxicity of copper. The effect of NO at high concentrations was, however, opposite. High concentrations of DEA/NO inhibited copper-mediated Acel activity. Correspondingly, high concentrations of DEA/NO (1 mM) dramatically enhanced copper toxicity. An intermediate concentration of DEA/NO (0.5 mM) exhibited a dual effect, enhancing toxicity at lower copper concentrations (<0.5 mM) and protecting at higher (> or =0.5 mM) copper concentrations. Thus, it is proposed that the ability of NO to both protect against (at low concentrations) and enhance (at high concentration) copper toxicity in S. cerevisiae is, at least partially, a result of its effect on Acel. The results of this study have implications for the role of NO as a mediator of metal metabolism.
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Affiliation(s)
- K T Chiang
- Department of Pharmacology, UCLA Medical School, Center for the Health Sciences, Los Angeles, California 90095, USA
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42
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Frederickson CJ, Suh SW, Silva D, Frederickson CJ, Thompson RB. Importance of zinc in the central nervous system: the zinc-containing neuron. J Nutr 2000; 130:1471S-83S. [PMID: 10801962 DOI: 10.1093/jn/130.5.1471s] [Citation(s) in RCA: 582] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Zinc is essential to the structure and function of myriad proteins, including regulatory, structural and enzymatic. It is estimated that up to 1% of the human genome codes for zinc finger proteins. In the central nervous system, zinc has an additional role as a neurosecretory product or cofactor. In this role, zinc is highly concentrated in the synaptic vesicles of a specific contingent of neurons, called "zinc-containing" neurons. Zinc-containing neurons are a subset of glutamatergic neurons. The zinc in the vesicles probably exceeds 1 mmol/L in concentration and is only weakly coordinated with any endogenous ligand. Zinc-containing neurons are found almost exclusively in the forebrain, where in mammals they have evolved into a complex and elaborate associational network that interconnects most of the cerebral cortices and limbic structures. Indeed, one of the intriguing aspects of these neurons is that they compose somewhat of a chemospecific "private line" of the mammalian cerebral cortex. The present review outlines (1) the methods used to discover, define and describe zinc-containing neurons; (2) the neuroarchitecture and synaptology of zinc-containing neural circuits; (3) the physiology of regulated vesicular zinc release; (4) the "life cycle" and molecular biology of vesicular zinc; (5) the importance of synaptically released zinc in the normal and pathological processes of the cerebral cortex; and (6) the role of specific and nonspecific stressors in the release of zinc.
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43
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Zhang P, Sawicki V, Lewis A, Hanson L, Monks J, Neville MC. The effect of serum iron concentration on iron secretion into mouse milk. J Physiol 2000; 522 Pt 3:479-91. [PMID: 10713971 PMCID: PMC2271065 DOI: 10.1111/j.1469-7793.2000.t01-2-00479.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
1. The concentration of iron in mouse milk is approximately 3 times that of the serum. Although there is clear evidence for the presence of the transferrin receptor in the rodent mammary gland, the precise mechanisms of iron transfer into milk are not known. 2. Milk iron was linearly related to the serum iron:transferrin ratio in lactating mice whose serum iron ranged from 8 to 66 microM. 3. Increasing the iron binding capacity of the milk by 340 microM by targeting the lactoferrin transgene to the mammary gland did not alter the relation between milk iron and the serum iron:transferrin ratio. 4. The steady-state distribution ratio of 125I-transferrin between plasma and milk was about 0.2, indicating that transcytosed transferrin contributed a maximum of 6% of the milk iron. 5. Fluorescently labelled transferrin incubated with the in situ gland localized mainly near the basal surface of the mammary alveolar cells. 6. These experiments provide evidence that the initial and rate-limiting step in the transfer of iron into milk is binding to a basal transferrin receptor. 7. A theoretical model of the relation between milk and serum iron suggests that the affinity of apotransferrin for the basal recycling system may be higher than observed in many other cell types.
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Affiliation(s)
- P Zhang
- Department of Physiology and Biophysics, University of Colorado Health Sciences Center, Denver 80262, USA
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44
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Andrews GK, Geiser J. Expression of the mouse metallothionein-I and -II genes provides a reproductive advantage during maternal dietary zinc deficiency. J Nutr 1999; 129:1643-8. [PMID: 10460198 DOI: 10.1093/jn/129.9.1643] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The function of metallothionein in zinc homeostasis was examined by using mice homozygous for knockout (KO) of the metallothionein-I or -II (MT-I and MT-II) genes. Pregnant MT-I/II KO mice or control mice were fed a zinc-deficient (1 microg/g or 5 microg/g) diet or a zinc-adequate (50 microg/g) diet during specific periods of pregnancy, and the effects on morphogenesis of the embryos were determined at day 14 of pregnancy (day 1 = vaginal plug). In the homozygous MT-I/II KO, as well as in the nontransgenic control mice, severe dietary zinc deficiency (1 microg/g) beginning on day 1 of pregnancy was embryotoxic and teratogenic, and the majority of the embryos in both strains were dead by mid-gestation. However, 53% of the surviving embryos in the MT-I/II KO mice were morphologically abnormal compared to only 32% of the embryos in the control mice. In subsequent experiments, moderate dietary zinc deficiency (5 microg/g beginning on day 1 of pregnancy or 1 microg/g dietary zinc beginning on day 8 of pregnancy) exerted teratogenic, but not embryotoxic effects. Embryos in the MT-I/II KO mice were 260 to 290% as likely to develop abnormally than were embryos in the control mice fed these same diets. These results demonstrate that the expression of the MT-I and -II genes in pregnant females improves reproductive success during maternal dietary zinc deficiency.
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Affiliation(s)
- G K Andrews
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160-7421, USA
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45
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46
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Lange H, Kispal G, Lill R. Mechanism of iron transport to the site of heme synthesis inside yeast mitochondria. J Biol Chem 1999; 274:18989-96. [PMID: 10383398 DOI: 10.1074/jbc.274.27.18989] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The import of metals, iron in particular, into mitochondria is poorly understood. Iron in mitochondria is required for the biosynthesis of heme and various iron-sulfur proteins. We have developed an in vitro assay to follow the uptake of iron into isolated yeast mitochondria. By measuring the incorporation of iron into porphyrin by ferrochelatase in the matrix, we were able to define the mechanism of iron import. Iron uptake is driven energetically by a membrane potential across the inner membrane but does not require ATP. Only reduced iron is functional in generating heme. Iron cannot be preloaded in the mitochondrial matrix but rather has to be transported across the inner membrane simultaneously with the synthesis of heme, suggesting that ferrochelatase receives iron directly from the inner membrane. Transport of iron is inhibited by manganese but not by zinc, nickel, and copper ions, explaining why in vivo these ions are not incorporated into porphyrin. The inner membrane proteins Mmt1p and Mmt2p proposed to be involved in mitochondrial iron movement are not required for the supply of ferrochelatase with iron. Iron transport can be reconstituted efficiently in a membrane potential-dependent fashion in proteoliposomes that were formed from a detergent extract of mitochondria. Our biochemical analysis of iron import into yeast mitochondria provides the basis for the identification of components involved in transport.
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Affiliation(s)
- H Lange
- Institut für Zytobiologie und Zytopathologie der Philipps-Universität Marburg, Robert-Koch-Strasse 5, 35033 Marburg, Germany
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47
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Costello LC, Liu Y, Zou J, Franklin RB. Evidence for a zinc uptake transporter in human prostate cancer cells which is regulated by prolactin and testosterone. J Biol Chem 1999; 274:17499-504. [PMID: 10364181 DOI: 10.1074/jbc.274.25.17499] [Citation(s) in RCA: 170] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The glandular epithelial cells of the human prostate gland have the unique capability and function of accumulating the highest zinc levels of any soft tissue in the body. Zinc accumulation in the prostate is regulated by prolactin and testosterone; however, little information is available concerning the mechanisms associated with zinc accumulation and its regulation in prostate epithelial cells. In the present studies the uptake and accumulation of zinc were determined in the human malignant prostate cell lines LNCaP and PC-3. The results demonstrate that LNCaP cells and PC-3 cells possess the unique capability of accumulating high levels of zinc. Zinc accumulation in both cell types is stimulated by physiological concentrations of prolactin and testosterone. The studies reveal that these cells contain a rapid zinc uptake process indicative of a plasma membrane zinc transporter. Initial kinetic studies demonstrate that the rapid uptake of zinc is effective under physiological conditions that reflect the total and mobile zinc levels in circulation. Correspondingly, genetic studies demonstrate the expression of a ZIP family zinc uptake transporter in both LNCaP and PC-3 cells. The rapid zinc uptake transport process is stimulated by treatment of cells with physiological levels of prolactin and testosterone, which possibly is the result of the regulation of the ZIP-type zinc transporter gene. These zinc-accumulating characteristics are specific for prostate cells. The studies support the concept that these prostate cells express a unique hormone-responsive, plasma membrane-associated, rapid zinc uptake transporter gene associated with their unique ability to accumulate high zinc levels.
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Affiliation(s)
- L C Costello
- Cellular and Molecular Biology Section, Department of Oral and Craniofacial Biological Sciences, University of Maryland Dental School, Baltimore, Maryland 21201, USA.
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48
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A putative iron regulatory protein (IRP)-encoding cDNA sequence in the ciliate Eufolliculina uhligi, and differential gene expression during the life cycle. Eur J Protistol 1999. [DOI: 10.1016/s0932-4739(99)80040-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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49
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McAbee DD, Jiang X. Copper and zinc ions differentially block asialoglycoprotein receptor-mediated endocytosis in isolated rat hepatocytes. J Biol Chem 1999; 274:14750-8. [PMID: 10329671 DOI: 10.1074/jbc.274.21.14750] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Asialoglycoprotein receptors on hepatocytes lose endocytic and ligand binding activity when hepatocytes are exposed to iron ions. Here, we report the effects of zinc and copper ions on the endocytic and ligand binding activity of asialoglycoprotein receptors on isolated rat hepatocytes. Treatment of cells at 37 degrees C for 2 h with ZnCl2 (0-220 microM) or CuCl2 (0-225 microM) reversibly blocked sustained endocytosis of 125I-asialoorosomucoid by up to 93% (t1/2 = 62 min) and 99% (t1/2 = 54 min), respectively. Cells remained viable during such treatments. Zinc- and copper-treated cells lost approximately 50% of their surface asialoglycoprotein receptor ligand binding activity; zinc-treated cells accumulated inactive asialoglycoprotein receptors intracellularly, whereas copper-treated cells accumulated inactive receptors on their surfaces. Cells treated at 4 degrees C with metal did not lose surface asialoglycoprotein receptor activity. Exposure of cells to copper ions, but not to zinc ions, blocked internalization of prebound 125I-asialoorosomucoid, but degradation of internalized ligand and pinocytosis of the fluid-phase marker Lucifer Yellow were not blocked by metal treatment. Zinc ions reduced diferric transferrin binding and endocytosis on hepatocytes by approximately 33%; copper ions had no inhibitory effects. These findings are the first demonstration of a specific inhibition of receptor-mediated endocytosis by non-iron transition metals.
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Affiliation(s)
- D D McAbee
- Department of Chemistry and Biochemistry, California State University, Long Beach, California 90840, USA.
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50
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Nagao M, Sugaru E, Kambe T, Sasaki R. Unidirectional transport from apical to basolateral compartment of cobalt ion in polarized Madin-Darby canine kidney cells. Biochem Biophys Res Commun 1999; 257:289-94. [PMID: 10198205 DOI: 10.1006/bbrc.1999.0446] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Renal transport of Co2+ was studied by use of cultured MDCK cells with cell polarity. Cells imported 57Co2+ from the apical membrane exclusively, while uptake from the basolateral membrane was minute. Apical uptake was time-, concentration-, pH-, and temperature- dependent and the dose-dependency curve was saturable, indicating that a carrier-mediated influx process operates in the apical membrane. The substrate specificity and other properties of this Co2+ transport process are distinct from those of a transporter DCT1, divalent cation transporter 1, with unusually broad substrate specificity including Co2+. Radioactive Co2+ added from the apical side appeared in the basolateral side, while there was only slight movement of Co2+ from the basolateral to apical side, indicating that this unidirectional transepithelial passage of Co2+ is not caused by the paracellular diffusion, but by the basolateral export of the cellular Co2+ uptake from the apical membrane. Our results may indicate the presence of a novel vectorial transport system responsible for the reabsorption of Co2+ from the glomerular filtrate.
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Affiliation(s)
- M Nagao
- Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan
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