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Ćwiertnia A, Kozłowski M, Cymbaluk-Płoska A. The Role of Iron and Cobalt in Gynecological Diseases. Cells 2022; 12:cells12010117. [PMID: 36611913 PMCID: PMC9818544 DOI: 10.3390/cells12010117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 12/12/2022] [Accepted: 12/26/2022] [Indexed: 12/29/2022] Open
Abstract
Iron and cobalt are micronutrients that play an important role in the regulation of cellular processes, being part of the centre of catalases, peroxidases, cytochromes and metalloproteins such as hemoglobin and myoglobin (Fe). Cobalt primarily functions as a component of hydroxycobalamin, which is essential for regulating red blood cell production. Maintaining normal levels of cobalt and iron in the human body is important, as a deficiency can lead to anaemia. These elements are also involved in reactions during which oxidative stress occurs and are therefore considered to be a cause of tumor formation. This paper will discuss aspects of the influence of cobalt and iron on mechanisms that may contribute to the growth of gynecological tumors, as well as other obstetric-gynecological disease entities, by altering the conditions of the microenvironment. In addition, the following review also highlights the role of cobalt and iron in the treatment of gynecological tumors.
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Red-light responsive photoCORM activated in aqueous acid solution. J Organomet Chem 2022. [DOI: 10.1016/j.jorganchem.2022.122578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rittase WB, Slaven JE, Suzuki YJ, Muir JM, Lee SH, Rusnak M, Brehm GV, Bradfield DT, Symes AJ, Day RM. Iron Deposition and Ferroptosis in the Spleen in a Murine Model of Acute Radiation Syndrome. Int J Mol Sci 2022; 23:ijms231911029. [PMID: 36232330 PMCID: PMC9570444 DOI: 10.3390/ijms231911029] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/08/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
Total body irradiation (TBI) can result in death associated with hematopoietic insufficiency. Although radiation causes apoptosis of white blood cells, red blood cells (RBC) undergo hemolysis due to hemoglobin denaturation. RBC lysis post-irradiation results in the release of iron into the plasma, producing a secondary toxic event. We investigated radiation-induced iron in the spleens of mice following TBI and the effects of the radiation mitigator captopril. RBC and hematocrit were reduced ~7 days (nadir ~14 days) post-TBI. Prussian blue staining revealed increased splenic Fe3+ and altered expression of iron binding and transport proteins, determined by qPCR, western blotting, and immunohistochemistry. Captopril did not affect iron deposition in the spleen or modulate iron-binding proteins. Caspase-3 was activated after ~7–14 days, indicating apoptosis had occurred. We also identified markers of iron-dependent apoptosis known as ferroptosis. The p21/Waf1 accelerated senescence marker was not upregulated. Macrophage inflammation is an effect of TBI. We investigated the effects of radiation and Fe3+ on the J774A.1 murine macrophage cell line. Radiation induced p21/Waf1 and ferritin, but not caspase-3, after ~24 h. Radiation ± iron upregulated several markers of pro-inflammatory M1 polarization; radiation with iron also upregulated a marker of anti-inflammatory M2 polarization. Our data indicate that following TBI, iron accumulates in the spleen where it regulates iron-binding proteins and triggers apoptosis and possible ferroptosis.
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Affiliation(s)
- W. Bradley Rittase
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - John E. Slaven
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Yuichiro J. Suzuki
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20007, USA
| | - Jeannie M. Muir
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Sang-Ho Lee
- Department of Laboratory Animal Research, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Milan Rusnak
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Grace V. Brehm
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Dmitry T. Bradfield
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Aviva J. Symes
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Regina M. Day
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
- Correspondence: ; Tel.: +1-301-295-3236; Fax: +1-301-295-3220
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Sherman HG, Jovanovic C, Stolnik S, Baronian K, Downard AJ, Rawson FJ. New Perspectives on Iron Uptake in Eukaryotes. Front Mol Biosci 2018; 5:97. [PMID: 30510932 PMCID: PMC6254016 DOI: 10.3389/fmolb.2018.00097] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/23/2018] [Indexed: 12/20/2022] Open
Abstract
All eukaryotic organisms require iron to function. Malfunctions within iron homeostasis have a range of physiological consequences, and can lead to the development of pathological conditions that can result in an excess of non-transferrin bound iron (NTBI). Despite extensive understanding of iron homeostasis, the links between the “macroscopic” transport of iron across biological barriers (cellular membranes) and the chemistry of redox changes that drive these processes still needs elucidating. This review draws conclusions from the current literature, and describes some of the underlying biophysical and biochemical processes that occur in iron homeostasis. By first taking a broad view of iron uptake within the gut and subsequent delivery to tissues, in addition to describing the transferrin and non-transferrin mediated components of these processes, we provide a base of knowledge from which we further explore NTBI uptake. We provide concise up-to-date information of the transplasma electron transport systems (tPMETSs) involved within NTBI uptake, and highlight how these systems are not only involved within NTBI uptake for detoxification but also may play a role within the reduction of metabolic stress through regeneration of intracellular NAD(P)H/NAD(P)+ levels. Furthermore, we illuminate the thermodynamics that governs iron transport, namely the redox potential cascade and electrochemical behavior of key components of the electron transport systems that facilitate the movement of electrons across the plasma membrane to the extracellular compartment. We also take account of kinetic changes that occur to transport iron into the cell, namely membrane dipole change and their consequent effects within membrane structure that act to facilitate transport of ions.
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Affiliation(s)
- Harry G Sherman
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | | | - Snow Stolnik
- Division of Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Kim Baronian
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Alison J Downard
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury, Christchurch, New Zealand
| | - Frankie J Rawson
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
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Krityakiarana W, Zhao PM, Nguyen K, Gomez-Pinilla F, Kotchabhakdi N, de Vellis J, Espinosa-Jeffrey A. Proof-of Concept that an Acute Trophic Factors Intervention After Spinal Cord Injury Provides an Adequate Niche for Neuroprotection, Recruitment of Nestin-Expressing Progenitors and Regeneration. Neurochem Res 2016; 41:431-49. [PMID: 26883642 PMCID: PMC5352162 DOI: 10.1007/s11064-016-1850-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 01/22/2016] [Accepted: 01/25/2016] [Indexed: 12/16/2022]
Abstract
Trophic factor treatment has been shown to improve the recovery of brain and spinal cord injury (SCI). In this study, we examined the effects of TSC1 (a combination of insulin-like growth factor 1 and transferrin) 4 and 8 h after SCI at the thoracic segment level (T12) in nestin-GFP transgenic mice. TSC1 treatment for 4 and 8 h increased the number of nestin-expressing cells around the lesion site and prevented Wallerian degeneration. Treatment with TSC1 for 4 h significantly increased heat shock protein (HSP)-32 and HSP-70 expression 1 and 2 mm from lesion site (both, caudal and rostral). Conversely, the number of HSP-32 positive cells decreased after an 8-h TSC1 treatment, although it was still higher than in both, non-treated SCI and intact spinal cord animals. Furthermore, TSC1 increased NG2 expressing cell numbers and preserved most axons intact, facilitating remyelination and repair. These results support our hypothesis that TSC1 is an effective treatment for cell and tissue neuroprotection after SCI. An early intervention is crucial to prevent secondary damage of the injured SC and, in particular, to prevent Wallerian degeneration.
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Affiliation(s)
- Warin Krityakiarana
- Departments of Neurobiology, Psychiatry and Biobehavioral Sciences, Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California, Los Angeles, 635 Charles E. Young Drive South, Suite 375E, Los Angeles, CA, 90095-7332, USA.
- Division of Physiotherapy, Faculty of Health Science, Srinakharinwirot University, Bangkok, Thailand.
| | - Paul M Zhao
- Departments of Neurobiology, Psychiatry and Biobehavioral Sciences, Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California, Los Angeles, 635 Charles E. Young Drive South, Suite 375E, Los Angeles, CA, 90095-7332, USA
| | - Kevin Nguyen
- Departments of Neurobiology, Psychiatry and Biobehavioral Sciences, Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California, Los Angeles, 635 Charles E. Young Drive South, Suite 375E, Los Angeles, CA, 90095-7332, USA
| | - Fernando Gomez-Pinilla
- Department of Physiological Sciences and Department of Neurosurgery, University of California at Los Angeles, Los Angeles, CA, USA
- Department of Physiology, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Naiphinich Kotchabhakdi
- Neuro-Behavioural Biology Center, Institute of Science and Technology for Research and Development, Mahidol University, 999 Phutthamonthol 4 Road, Salaya, Phutthamonthol, Nakornpathom, 73170, Thailand
| | - Jean de Vellis
- Departments of Neurobiology, Psychiatry and Biobehavioral Sciences, Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California, Los Angeles, 635 Charles E. Young Drive South, Suite 375E, Los Angeles, CA, 90095-7332, USA
| | - Araceli Espinosa-Jeffrey
- Departments of Neurobiology, Psychiatry and Biobehavioral Sciences, Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California, Los Angeles, 635 Charles E. Young Drive South, Suite 375E, Los Angeles, CA, 90095-7332, USA.
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Indira Chandran V, Matesic L, Locke JM, Skropeta D, Ranson M, Vine KL. Anti-cancer activity of an acid-labile N-alkylisatin conjugate targeting the transferrin receptor. Cancer Lett 2012; 316:151-6. [DOI: 10.1016/j.canlet.2011.10.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 09/21/2011] [Accepted: 10/16/2011] [Indexed: 12/18/2022]
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Bou-Abdallah F, Terpstra TR. The thermodynamic and binding properties of the transferrins as studied by isothermal titration calorimetry. Biochim Biophys Acta Gen Subj 2011; 1820:318-25. [PMID: 21843602 DOI: 10.1016/j.bbagen.2011.07.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 07/16/2011] [Accepted: 07/21/2011] [Indexed: 02/01/2023]
Abstract
BACKGROUND In mammals, serum-transferrins transport iron from the neutral environment of the blood to the cytoplasm by receptor-mediated endocytosis. Extensive in-vitro studies have focused on the thermodynamics and kinetics of Fe(3+) binding to a number of transferrins. However, little attention has been given to the thermodynamic characterization of the interaction of transferrin with its receptor. SCOPE OF REVIEW Iron-loaded transferrin (Tf) binds with high affinity to the specific transferrin receptor (TfR) on the cell surface. The Tf-TfR complex is then internalized via receptor mediated endocytosis into an endosome where iron is released. Here, we provide an overview of recent studies that have used ITC to quantify the interaction of various metal ions with transferrin and highlight our current understanding of the thermodynamics of the transferrin-transferrin receptor system at physiological pH. GENERAL SIGNIFICANCE The interaction of the iron-loaded transferrin with the transferrin receptor is a key cellular process that occurs during the normal course of iron metabolism. Understanding the thermodynamics of this interaction is important for iron homeostasis since the physiological requirement of iron must be appropriately maintained to avoid iron-related diseases. MAJOR CONCLUSIONS The thermodynamic data revealed stoichiometric binding of all tested metal ions to transferrin with very high affinities ranging between 10(17) and 10(22)M(-1). Iron-loaded transferrin (monoferric or diferric) is shown to bind avidly (K~10(7)-10(8)M(-1)) to the receptor at neutral pH with a stoichiometry of one Tf molecule per TfR monomer. Significantly, both the N- and the C-lobe contribute to the binding interaction which is shown to be both enthalpically and entropically driven. This article is part of a Special Issue entitled Transferrins: Molecular mechanisms of iron transport and disorders.
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Affiliation(s)
- Fadi Bou-Abdallah
- Department of Chemistry, State University of New York at Potsdam, Potsdam, NY 13676, USA.
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Cell-autonomous and systemic context-dependent functions of iron regulatory protein 2 in mammalian iron metabolism. Blood 2008; 113:679-87. [PMID: 18922858 DOI: 10.1182/blood-2008-05-155093] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mice with total and constitutive iron regulatory protein 2 (IRP2) deficiency exhibit microcytosis and altered body iron distribution with duodenal and hepatic iron loading and decreased iron levels in splenic macrophages. To explore cell-autonomous and systemic context-dependent functions of IRP2 and to assess the systemic consequences of local IRP2 deficiency, we applied Cre/Lox technology to specifically ablate IRP2 in enterocytes, hepatocytes, or macrophages, respectively. This study reveals that the hepatic and duodenal manifestations of systemic IRP2 deficiency are largely explained by cell-autonomous functions of IRP2. By contrast, IRP2-deficient macrophages from otherwise IRP2-sufficient mice do not display the abnormalities of macrophages from systemically IRP2-deficient animals, suggesting that these result from IRP2 disruption in other cell type(s). Mice with enterocyte-, hepatocyte-, or macrophage-specific IRP2 deficiency display normal red blood cell and plasma iron parameters, supporting the notion that the microcytosis in IRP2-deficient mice likely reflects an intrinsic defect in hematopoiesis. This work defines the respective roles of IRP2 in the determination of critical body iron parameters such as organ iron loading and erythropoiesis.
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Simoni J, Simoni G, Griswold JA, Moeller JF, Tsikouris JP, Khanna A, Roongsritong C, Wesson DE. Role of Free Hemoglobin in 8-Iso Prostaglandin F2-Alpha Synthesis in Chronic Renal Failure and Its Impact on CD163-Hb Scavenger Receptor and on Coronary Artery Endothelium. ASAIO J 2006; 52:652-61. [PMID: 17117055 DOI: 10.1097/01.mat.0000235282.89757.9f] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Free hemoglobin (Hb) during autoxidation increases 8-iso-prostaglandin-F2-alpha (8-isoprostane) formation in vitro. Because 8-isoprostane and plasma Hb are elevated in chronic renal failure (CRF), we evaluated the role of Hb in this isoprostane synthesis in vivo. By monitoring correlations between Hb, haptoglobin (Hp), CD163-Hb-scavenger receptor, and 8-isoprostane that is known to induce CD163 shedding, we examined whether 8-isoprostane blocks Hb catabolism in CRF. Additionally, by studying the effect of 8-isoprostane on human coronary artery endothelium (HCAEC) in vitro and its impact on intercellular adhesion molecule-1 (ICAM-1) in vivo, we tested its role in promotion of cardiovascular events in CRF. Twenty-two never-dialyzed CRF patients and 18 control patients were screened for renal function, plasma and urine 8-isoprostane, and plasma Hb, Hp, thiobarbituric-acid-reactants (TBARS), C-reactive-protein (CRP), and soluble (s) ICAM-1 and sCD163. HCAEC exposed to 8-isoprostane were tested for ICAM-1 and apoptosis. In CRF, urine 8-isoprostane was significantly elevated and correlated with free-Hb and TBARS. The increased free-Hb, Hp, and sCD163 in CRF suggested 8-isoprostane-mediated suppression of Hb catabolism through CD163 receptor shedding. 8-Isoprostane enhanced ICAM-1 expression and apoptosis in HCAEC. CRF patients showed elevated sICAM-1. In conclusion, free-Hb, via 8-isoprostane, paradoxically blocks its own catabolism. Free-Hb and/or 8-isoprostane may intensify cardiovascular events in CRF.
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Affiliation(s)
- Jan Simoni
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA
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Xiu-Lian D, Kui W, Ya K, Lan Y, Rong-Chang L, Yan Zhong C, Kwok Ping H, Zhong Ming Q. Apotransferrin is internalized and distributed in the same way as holotransferrin in K562 cells. J Cell Physiol 2004; 201:45-54. [PMID: 15281088 DOI: 10.1002/jcp.20051] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Transferrin (Tf), a naturally existing protein, has received considerable attention in the area of drug targeting since it is biodegradable, non-toxic, and non-immunogenic. The efficient cellular uptake of Tf shows it has potential in the delivery of anti-cancer drugs, proteins, and therapeutic genes into proliferating malignant cells that overexpress transferrin receptor (TfR). In human serum, about 30% of Tf exists in the iron-saturated form (Fe(2)-Tf) and the remainder exists as apotransferrin (apo-Tf). Understanding the uptake of apo-Tf by cells will provide key insights into studies on Tf-mediated drug delivery. In the present study, we investigated visually the transport of apo-Tf into K562 cells and its intracellular localization by laser-scanning confocal microscopy (LSCM) and flow cytometry analysis (FCA). It was found that, like Fe(2)-Tf, apo-Tf can be taken up into the cells. The process is time- and temperature-dependent, competitively inhibited by Fe(2)-Tf, and significantly abolished by pronase pretreatment. Visual evidence showed that the transport of apo-Tf into K562 cells is a TfR-mediated process. Furthermore, the investigations using optical-slicing technique demonstrated that the distribution of apo-Tf is similar to that of Fe(2)-Tf, both appearing in the perinuclear region in ball-in-bowl shape.
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Affiliation(s)
- Du Xiu-Lian
- School of Pharmaceutical Science and Joint Laboratory of Perking University & The Hong Kong Polytechnic University, Perking University, Beijing, People's Republic of China
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Wojda U, Goldsmith P, Miller JL. Surface membrane biotinylation efficiently mediates the endocytosis of avidin bioconjugates into nucleated cells. Bioconjug Chem 1999; 10:1044-50. [PMID: 10563774 DOI: 10.1021/bc990059z] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here we demonstrate that biotin covalently attached to cell surface obligates existing receptors to endocytose avidin bioconjugates into nucleated cells. Incubation of fluorescein-labeled avidin with biotinylated cell lines resulted in uniform and rapid surface attachment and endocytosis compared with no detectable association of the avidin-conjugated dye with unbiotinylated cells. Uptake was detected within minutes with efficiencies approaching 100% in cell lines and freshly obtained peripheral blood mononuclear cells. After 24 h, avidin was barely detectable on the surface of the nucleated cells. In marked contrast, fluorescent avidin remained exclusively on the external membrane of erythrocytes after 24 h. To investigate biotin-mediated endocytosis for the delivery of DNA, we prepared polyethylenimine-avidin (PEI-avidin) conjugates. Surface biotinylation significantly increased the transfection efficiencies of PEI-avidin condensed plasmid DNA coding green fluorescent protein (GFP) to the level of transferrin-receptor targeted gene delivery (15-20% GFP positive cells in culture after 48 h). The increase in transfection efficiency was blocked by the addition of free avidin or biotin to the culture medium. Biotin covalently bound to cell surface membrane proteins efficiently mediates the entry of avidin bioconjugates into nucleated cells.
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Affiliation(s)
- U Wojda
- Laboratory of Chemical Biology, National Institute of Diabetes and Digestive and Kidney Diseases and Metabolic Disease Branch, National Institutes of Health, Bethesda, Maryland 20892, USA
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Savigni DL, Morgan EH. Transport mechanisms for iron and other transition metals in rat and rabbit erythroid cells. J Physiol 1998; 508 ( Pt 3):837-50. [PMID: 9518737 PMCID: PMC2230914 DOI: 10.1111/j.1469-7793.1998.837bp.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
1. Earlier studies have shown that Fe2+ transport into erythroid cells is inhibited by several transition metals (Mn2+, Zn2+, Co2+, Ni2+) and that Fe2+ transport can occur by two saturable mechanisms, one of high affinity and the other of low affinity. Also, the transport of Zn2+ and Cd2+ into erythroid cells is stimulated by NaHCO3 and NaSCN. The aim of the present investigation was to determine whether all of these transition metals can be transported by the processes described for Fe2+, Zn2+ and Cd2+ and to determine the properties of the transport processes. 2. Rabbit reticulocytes and mature erythrocytes and reticulocytes from homozygous and heterozygous Belgrade rats were incubated with radiolabelled samples of the metals under conditions known to be optimal for high- and low-affinity Fe2+ transport and for the processes mediated by NaHCO3 and NaSCN. 3. All of the metals were transported by the high- and low-affinity Fe2+ transport processes and could compete with each other for transport. The Km and Vmax values and the effects of incubation temperature and metabolic inhibitors were similar for all the metals. NaHCO3 and NaSCN increased the uptake of Zn2+ and Cd2+ but not the other metals. 4. The uptake of all of the metals by the high-affinity process was much lower in reticulocytes from homozygous Belgrade rats than in those from heterozygous animals, but there was no difference with respect to low-affinity transport. 5. It is concluded that the high- and low-affinity 'iron' transport mechanisms can also transport several other transition metals and should therefore be considered as general transition metal carriers.
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Affiliation(s)
- D L Savigni
- Department of Physiology, The University of Western Australia, Nedlands, Western Australia 6907, Australia
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