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Fiorito V, Tolosano E. Unearthing FLVCR1a: tracing the path to a vital cellular transporter. Cell Mol Life Sci 2024; 81:166. [PMID: 38581583 PMCID: PMC10998817 DOI: 10.1007/s00018-024-05205-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 03/08/2024] [Accepted: 03/13/2024] [Indexed: 04/08/2024]
Abstract
The Feline Leukemia Virus Subgroup C Receptor 1a (FLVCR1a) is a member of the SLC49 Major Facilitator Superfamily of transporters. Initially recognized as the receptor for the retrovirus responsible of pure red cell aplasia in cats, nearly two decades since its discovery, FLVCR1a remains a puzzling transporter, with ongoing discussions regarding what it transports and how its expression is regulated. Nonetheless, despite this, the substantial body of evidence accumulated over the years has provided insights into several critical processes in which this transporter plays a complex role, and the health implications stemming from its malfunction. The present review intends to offer a comprehensive overview and a critical analysis of the existing literature on FLVCR1a, with the goal of emphasising the vital importance of this transporter for the organism and elucidating the interconnections among the various functions attributed to this transporter.
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Affiliation(s)
- Veronica Fiorito
- Molecular Biotechnology Center (MBC) "Guido Tarone", Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126, Turin, Italy
| | - Emanuela Tolosano
- Molecular Biotechnology Center (MBC) "Guido Tarone", Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126, Turin, Italy.
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2
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Jahn MR, Shukoor I, Tremel W, Wolfrum U, Kolb U, Nawroth T, Langguth P. Hemin-coupled iron(III)-hydroxide nanoparticles show increased uptake in Caco-2 cells. J Pharm Pharmacol 2011; 63:1522-30. [DOI: 10.1111/j.2042-7158.2011.01356.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Abstract
Objectives
The absorption of commonly used ferrous iron salts from intestinal segments at neutral to slightly alkaline pH is low, mainly because soluble ferrous iron is easily oxidized to poorly soluble ferric iron and ferrous iron but not ferric iron is carried by the divalent metal transporter DMT-1. Moreover, ferrous iron frequently causes gastrointestinal side effects. In iron(III)-hydroxide nanoparticles hundreds of ferric iron atoms are safely packed in nanoscaled cores surrounded by a solubilising carbohydrate shell, yet bioavailability from such particles is insufficient when compared with ferrous salts. To increase their intestinal uptake iron(III)-hydroxide nanoparticles were coupled in this study with the protoporphyrin hemin, which undergoes carrier-mediated uptake in the intestine.
Methods
Uptake of iron(III)-hydroxide nanoparticles with hemin covalently coupled by DCC reaction was measured in Caco-2 cells with a colorimetric assay and visualized by transmission electron microscopy.
Key findings
Nanoparticles were taken up by carrier-mediated transport, since uptake was temperature-dependent and increased with an increasing hemin substitution grade. Furthermore, uptake decreased with an increasing concentration of free hemin, due to competition for carrier-mediated uptake.
Conclusions
Hemin-coupled iron(III)-hydroxide nanoparticles were carried by a heme specific transport system, probably via receptor mediated endocytosis. It can be expected that this system shows improved absorption of iron compared with uncoupled iron(III)-hydroxide nanoparticles, which exist on the market today.
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Affiliation(s)
- Markus Richard Jahn
- Biopharmacy and Pharmaceutical Technology, Institute of Pharmacy and Biochemistry, Mainz, Germany
| | - Ibrahim Shukoor
- Institute of Inorganic and Analytical Chemistry, Mainz, Germany
| | - Wolfgang Tremel
- Institute of Inorganic and Analytical Chemistry, Mainz, Germany
| | - Uwe Wolfrum
- Cell and Matrix Biology, Institute of Zoology, Mainz, Germany
| | - Ute Kolb
- Institute of Physical Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Thomas Nawroth
- Biopharmacy and Pharmaceutical Technology, Institute of Pharmacy and Biochemistry, Mainz, Germany
| | - Peter Langguth
- Biopharmacy and Pharmaceutical Technology, Institute of Pharmacy and Biochemistry, Mainz, Germany
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3
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Haem and folate transport by proton-coupled folate transporter/haem carrier protein 1 (SLC46A1). Br J Nutr 2008; 101:1150-6. [PMID: 18782461 DOI: 10.1017/s0007114508066762] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Haem carrier protein 1 (HCP1) was originally identified and characterised as a mammalian haem transporter. However, recent evidence has shown that it is also a proton-coupled folate transporter (PCFT) and mutations in the gene cause hereditary folate deficiency in humans. We therefore investigated haem and folate transport characteristics of PCFT/HCP1 both in vivo and in vitro in CD-1 mice and in the presence or absence of a blocking antibody for PCFT/HCP1, and also in cultured cells (which express PCFT/HCP1 endogenously) to elucidate the specificity and selectivity of PCFT/HCP1. The in vivo study showed that the addition of folic acid inhibited 59Fe-labelled haem transport in hypoxic mice but had no effect in normal mice. Using in vitro methods, the results showed increased [3H]folate uptake into everted duodenum from hypoxic mice but uptake was reduced by the addition of haem or PCFT/HCP1 antibodies to the medium. Caco-2 cells transiently transfected with small interfering RNA (siRNA) PCFT/HCP1 duplex oligos resulted in a 69 % reduction in PCFT/HCP1 mRNA when compared with the control siRNA. Both haem and folate uptake were significantly (P < 0.05) reduced in cells transfected with PCFT/HCP1 siRNA; however, the magnitude of reduction with folic acid uptake was greater (48 %) than that of haem (22.5 %). Overall the data support PCFT/HCP1 as a primary folate transporter with a lower affinity for haem. PCFT/HCP1 could therefore play a physiological role in Fe nutrition and the data highlight the potential for the interaction of folate and haem at the level of intestinal absorption.
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4
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Porto BN, Alves LS, Fernández PL, Dutra TP, Figueiredo RT, Graça-Souza AV, Bozza MT. Heme induces neutrophil migration and reactive oxygen species generation through signaling pathways characteristic of chemotactic receptors. J Biol Chem 2007; 282:24430-6. [PMID: 17581818 DOI: 10.1074/jbc.m703570200] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hemolysis or extensive cell damage can lead to high concentrations of free heme, causing oxidative stress and inflammation. Considering that heme induces neutrophil chemotaxis, we hypothesize that heme activates a G protein-coupled receptor. Here we show that similar to heme, several heme analogs were able to induce neutrophil migration in vitro and in vivo. Mesoporphyrins, molecules lacking the vinyl groups in their rings, were not chemotactic for neutrophils and selectively inhibited heme-induced migration. Moreover, migration of neutrophils induced by heme was abolished by pretreatment with pertussis toxin, an inhibitor of Galpha inhibitory protein, and with inhibitors of phosphoinositide 3-kinase, phospholipase Cbeta, mitogen-activated protein kinases, or Rho kinase. The induction of reactive oxygen species by heme was dependent of Galpha inhibitory protein and phosphoinositide 3-kinase and partially dependent of phospholipase Cbeta, protein kinase C, mitogen-activated protein kinases, and Rho kinase. Together, our results indicate that heme activates neutrophils through signaling pathways that are characteristic of chemoattractant molecules and suggest that mesoporphyrins might prove valuable in the treatment of the inflammatory consequences of hemorrhagic and hemolytic disorders.
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Affiliation(s)
- Bárbara N Porto
- Departamento de Imunologia, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, 21.941-590 Brasil
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5
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Figueiredo RT, Fernandez PL, Mourao-Sa DS, Porto BN, Dutra FF, Alves LS, Oliveira MF, Oliveira PL, Graça-Souza AV, Bozza MT. Characterization of heme as activator of Toll-like receptor 4. J Biol Chem 2007; 282:20221-9. [PMID: 17502383 DOI: 10.1074/jbc.m610737200] [Citation(s) in RCA: 427] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Heme is an ancient and ubiquitous molecule present in organisms of all kingdoms, composed of an atom of iron linked to four ligand groups of porphyrin. A high amount of free heme, a potential amplifier of the inflammatory response, is a characteristic feature of diseases with increased hemolysis or extensive cell damage. Here we demonstrate that heme, but not its analogs/precursors, induced tumor necrosis factor-alpha (TNF-alpha) secretion by macrophages dependently on MyD88, TLR4, and CD14. The activation of TLR4 by heme is exquisitely strict, requiring its coordinated iron and the vinyl groups of the porphyrin ring. Signaling of heme through TLR4 depended on an interaction distinct from the one established between TLR4 and lipopolysaccharide (LPS) since anti-TLR4/MD2 antibody or a lipid A antagonist inhibited LPS-induced TNF-alpha secretion but not heme activity. Conversely, protoporphyrin IX antagonized heme without affecting LPS-induced activation. Moreover, heme induced TNF-alpha and keratinocyte chemokine but was ineffective to induce interleukin-6, interleukin-12, and interferon-inducible protein-10 secretion or co-stimulatory molecule expression. These findings support the concept that the broad ligand specificity of TLR4 and the different activation profiles might in part reside in its ability to recognize different ligands in different binding sites. Finally, heme induced oxidative burst, neutrophil recruitment, and heme oxygenase-1 expression independently of TLR4. Thus, our results presented here reveal a previous unrecognized role of heme as an extracellular signaling molecule that affects the innate immune response through a receptor-mediated mechanism.
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Affiliation(s)
- Rodrigo T Figueiredo
- Departamento de Imunologia, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil
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6
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Markel TA, Crisostomo PR, Wang M, Herring CM, Meldrum KK, Lillemoe KD, Meldrum DR. The struggle for iron: gastrointestinal microbes modulate the host immune response during infection. J Leukoc Biol 2007; 81:393-400. [PMID: 17255516 DOI: 10.1189/jlb.0906579] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The gastrointestinal track is one source of potential bacterial entry into the host, and the local immune system at the mucosal border is paramount in establishing host immune tolerance and the immune response to invading organisms. Macrophages use iron for production of hydroxy-radical and superoxide reactions, which are necessary for microbial killing. Presumably, as a survival strategy, bacteria, which also require iron for survival, have adapted the ability to sequester iron from the host, thereby limiting the availability to macrophages. As current modes of antimicrobial therapy are evolving, examination of nontraditional therapies is emerging. One such potential therapy involves altering the bacterial micronutrient iron concentration. Necrotizing enterocolitis is a clinical condition where such a strategy makes intuitive sense. This review will describe the immune response to gastrointestinal infection, the mechanisms that the gastrointestinal system uses to absorb intraluminal iron, and the critical role iron plays in the infectious process.
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Affiliation(s)
- Troy A Markel
- Department of Surgery, Indiana University School of Medicine, Emerson Hall 215, Indianapolis, IN 46202, USA
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7
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Oates PS, West AR. Heme in intestinal epithelial cell turnover, differentiation, detoxification, inflammation, carcinogenesis, absorption and motility. World J Gastroenterol 2006; 12:4281-95. [PMID: 16865768 PMCID: PMC4087737 DOI: 10.3748/wjg.v12.i27.4281] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The gastrointestinal tract is lined by a simple epithelium that undergoes constant renewal involving cell division, differentiation and cell death. In addition, the epithelial lining separates the hostile processes of digestion and absorption that occur in the intestinal lumen from the aseptic environment of the internal milieu by defensive mechanisms that protect the epithelium from being breached. Central to these defensive processes is the synthesis of heme and its catabolism by heme oxygenase (HO). Dietary heme is also an important source of iron for the body which is taken up intact by the enterocyte. This review describes the recent literature on the diverse properties of heme/HO in the intestine tract. The roles of heme/HO in the regulation of the cell cycle/apoptosis, detoxification of xenobiotics, oxidative stress, inflammation, development of colon cancer, heme-iron absorption and intestinal motility are specifically examined.
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8
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Foresti R, Bains S, Sulc F, Farmer PJ, Green CJ, Motterlini R. The Interaction of Nitric Oxide with Distinct Hemoglobins Differentially Amplifies Endothelial Heme Uptake and Heme Oxygenase-1 Expression. J Pharmacol Exp Ther 2006; 317:1125-33. [PMID: 16495208 DOI: 10.1124/jpet.105.097907] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Heme is a strong inducer and substrate of the stress protein heme oxygenase-1 (HO-1), which produces carbon monoxide, iron, and bilirubin. We have reported recently that nitric oxide (NO) augments the incorporation of free hemin in endothelial cells, resulting in amplified HO-1 expression and production of bilirubin. Here, we extend our studies by showing that both NO+ and NO- donors interacted with reduced (HbA0) or oxidized (metHb) hemoglobin, as well as hemoglobin from sickle cell disease (HbS), to strongly magnify HO-1, with a pattern of induction dependent on the oxidation state of the hemoglobin used. A corresponding enhancement of endothelial heme uptake was observed following exposure of HbA0 or HbS to the NO donors, which also increased the uptake of free hemin. We postulated that this effect may be caused by formation of heme-nitrosyl (H-NO) complexes, and indeed endothelial cells exposed to preformed H-NO showed greater heme incorporation than free hemin. Furthermore, NO donors directly affected the permeability of membranes to free hemin. In conclusion, our data indicate a novel role for NO in the modulation of heme transport and HO-1 induction in endothelial cells, which may be relevant for hematological disorders characterized by disruption of the heme-NO equilibrium.
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Affiliation(s)
- Roberta Foresti
- Vascular Biology Unit, Department of Surgical Research, Northwick Park Institute for Medical Research, Watford Road, Harrow, Middlesex, HA1 3UJ, UK.
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9
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Babusiak M, Man P, Sutak R, Petrak J, Vyoral D. Identification of heme binding protein complexes in murine erythroleukemic cells: Study by a novel two-dimensional native separation - liquid chromatography and electrophoresis. Proteomics 2005; 5:340-50. [PMID: 15627969 DOI: 10.1002/pmic.200400935] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the current postgenomic era there is a growing interest in analysis of protein complexes in their native state. Here we present a novel two-dimensional separation technique for assessment of native protein complexes. The method combines native chromatography with native electrophoresis. The approach was used to study heme-binding protein complexes in murine erythroleukemia cells. The cells were metabolically labeled with [(59)Fe]-heme and cellular lysates were separated by anion-exchange chromatography. Fractions containing the (59)Fe isotope were collected, concentrated and further separated by native gel electrophoresis. A total of 13 radioactive protein bands were detected and analyzed by liquid chromatography-tandem mass spectrometry. Thirty-three individual proteins were identified and attributed to four novel multiprotein complexes representing four different 'snapshots' of cellular events involved in hemoglobin biosynthesis.
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Affiliation(s)
- Marek Babusiak
- Institute of Hematology and Blood Transfusion, Prague, Czech Republic.
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10
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Uc A, Stokes JB, Britigan BE. Heme transport exhibits polarity in Caco-2 cells: evidence for an active and membrane protein-mediated process. Am J Physiol Gastrointest Liver Physiol 2004; 287:G1150-7. [PMID: 15308469 DOI: 10.1152/ajpgi.00157.2004] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Heme prosthetic groups are vital for all living organisms, but they can also promote cellular injury by generating reactive oxygen species. Therefore, intestinal heme absorption and distribution should be carefully regulated. Although a human intestine brush-border heme receptor/transporter has been suggested, the mechanism by which heme crosses the apical membrane is unknown. After it enters the cell, heme is degraded by heme oxygenase-1 (HO-1), and iron is released. We hypothesized that heme transport is actively regulated in Caco-2 cells. Cells exposed to hemin from the basolateral side demonstrated a higher HO-1 induction than cells exposed to hemin from the apical surface. Hemin secretion was more rapid than absorption, and net secretion occurred against a concentration gradient. Treatment of the apical membrane with trypsin increased hemin absorption by threefold, but basolateral treatment with trypsin had no effect on hemin secretion. Neither apical nor basolateral trypsin changed the paracellular pathway. We conclude that heme is acquired and transported in both absorptive and secretory directions in polarized Caco-2 cells. Secretion is via an active metabolic/transport process. Trypsin applied to the apical surface increased hemin absorption, suggesting that protease activity can uncover a process for heme uptake that is otherwise quiescent. These processes may be involved in preventing iron overload in humans.
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Affiliation(s)
- Aliye Uc
- Department of Pediatrics, Veterans Administration Medical Center, University of Iowa, Iowa City, IA 52242, USA.
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11
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Quigley JG, Yang Z, Worthington MT, Phillips JD, Sabo KM, Sabath DE, Berg CL, Sassa S, Wood BL, Abkowitz JL. Identification of a human heme exporter that is essential for erythropoiesis. Cell 2004; 118:757-66. [PMID: 15369674 DOI: 10.1016/j.cell.2004.08.014] [Citation(s) in RCA: 296] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Revised: 07/22/2004] [Accepted: 07/27/2004] [Indexed: 01/11/2023]
Abstract
FLVCR, a member of the major facilitator superfamily of transporter proteins, is the cell surface receptor for feline leukemia virus, subgroup C. Retroviral interference with FLVCR display results in a loss of erythroid progenitors (colony-forming units-erythroid, CFU-E) and severe anemia in cats. In this report, we demonstrate that human FLVCR exports cytoplasmic heme and hypothesize that human FLVCR is required on developing erythroid cells to protect them from heme toxicity. Inhibition of FLVCR in K562 cells decreases heme export, impairs their erythroid maturation and leads to apoptosis. FLVCR is upregulated on CFU-E, indicating that heme export is important in primary cells at this stage. Studies of FLVCR expression in cell lines suggest this exporter also impacts heme trafficking in intestine and liver. To our knowledge, this is the first description of a mammalian heme transporter.
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Affiliation(s)
- John G Quigley
- Department of Medicine/Hematology, University of Washington, Seattle 98195, USA
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12
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Worthington MT, Cohn SM, Miller SK, Luo RQ, Berg CL. Characterization of a human plasma membrane heme transporter in intestinal and hepatocyte cell lines. Am J Physiol Gastrointest Liver Physiol 2001; 280:G1172-7. [PMID: 11352810 DOI: 10.1152/ajpgi.2001.280.6.g1172] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Heme is the most bioavailable form of dietary iron and a component of many cellular proteins. Controversy exists as to whether heme uptake occurs via specific transport mechanisms or passive diffusion. The aims of this study were to quantify cellular heme uptake with a fluorescent heme analog and to determine whether heme uptake is mediated by a heme transporter in intestinal and hepatic cell lines. A zinc-substituted porphyrin, zinc mesoporphyrin (ZnMP), was validated as a heme homolog in uptake studies of intestinal (Caco-2, I-407) and hepatic (HepG2) cell lines. Uptake experiments to determine time dependence, heme inhibition, concentration dependence, temperature dependence, and response to the heme synthesis inhibitor succinylacetone were performed. Fluorescence microscope images were used to quantify uptake and determine the cellular localization of ZnMP; ZnMP uptake was seen in intestinal and hepatic cell lines, with cytoplasmic uptake and nuclear sparing. Uptake was dose- and temperature dependent, inhibited by heme competition, and saturated over time. Preincubation with succinylacetone augmented uptake, with an increased initial uptake rate. These findings establish a new method for quantifying heme uptake in individual cells and provide strong evidence that this uptake is a regulated, carrier-mediated process.
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Affiliation(s)
- M T Worthington
- Digestive Health Research Center, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA.
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13
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Takle GB, Thierry AR, Flynn SM, Peng B, White L, Devonish W, Galbraith RA, Goldberg AR, George ST. Delivery of oligoribonucleotides to human hepatoma cells using cationic lipid particles conjugated to ferric protoporphyrin IX (heme). ANTISENSE & NUCLEIC ACID DRUG DEVELOPMENT 1997; 7:177-85. [PMID: 9212908 DOI: 10.1089/oli.1.1997.7.177] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The receptor-ligand interaction between hepatocyte heme receptors and heme was evaluated as a basis for developing a targeted cationic lipid delivery reagent for nucleic acids. Heme (ferric protoporphyrin IX) was conjugated to the aminolipid dioleoyl phosphatidylethanolamine (DOPE) and used to form cationic lipid particles with dioleoyl trimethylammonium propane (DOTAP). These lipids particles (DDH) protect oligoribonucleotides from degradation in human serum and increase oligoribonucleotide uptake into 2.2.15 human hepatoma cells (to a level of 50-60 ng oligo/10(4) cells) when compared with the same lipid particles (DD) prepared identically without heme. The DDH heme level that was optimal for oligoribonucleotide delivery was also optimal for maximum expression of plasmid-encoded luciferase. The enhancing effect of heme was evident only at net particle negative charge. Fluorescence microscopy showed that DDH delivered oligoribonucleotides into both the 2.2.15 cell cytoplasm and nucleus. DDH may thus be a potentially useful delivery vehicle for oligonucleotide-based therapeutics and transgenes, appropriate for use in such liver diseases as viral hepatitis, hepatoma, and hypercholesterolemia.
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MESH Headings
- Animals
- Carcinoma, Hepatocellular/pathology
- Cations
- Cell Line
- Cell Nucleus/metabolism
- Chlorocebus aethiops
- Cytoplasm/metabolism
- DNA, Recombinant/administration & dosage
- DNA, Recombinant/pharmacokinetics
- Drug Carriers
- Fatty Acids, Monounsaturated/administration & dosage
- Fatty Acids, Monounsaturated/chemistry
- Fatty Acids, Monounsaturated/pharmacokinetics
- Genes, Reporter
- Genetic Vectors/administration & dosage
- Genetic Vectors/pharmacokinetics
- Heme/administration & dosage
- Heme/chemistry
- Heme/pharmacokinetics
- Humans
- Kidney
- Liver Neoplasms/pathology
- Luciferases/biosynthesis
- Luciferases/genetics
- Mice
- Microscopy, Fluorescence
- Neoplasm Proteins/metabolism
- Oligoribonucleotides/administration & dosage
- Oligoribonucleotides/chemistry
- Oligoribonucleotides/pharmacokinetics
- Organ Specificity
- Particle Size
- Phosphatidylethanolamines/administration & dosage
- Phosphatidylethanolamines/chemistry
- Phosphatidylethanolamines/pharmacokinetics
- Quaternary Ammonium Compounds/administration & dosage
- Quaternary Ammonium Compounds/chemistry
- Quaternary Ammonium Compounds/pharmacokinetics
- Receptors, Cell Surface/metabolism
- Recombinant Fusion Proteins/biosynthesis
- Recombinant Fusion Proteins/genetics
- Species Specificity
- Tumor Cells, Cultured
- Vero Cells
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Affiliation(s)
- G B Takle
- Innovir Laboratories, Inc., New York, NY 10021, USA
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14
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Duthie SJ, Melvin WT, Burke MD. Bromobenzene detoxification in the human liver-derived HepG2 cell line. Xenobiotica 1994; 24:265-79. [PMID: 8009889 DOI: 10.3109/00498259409043238] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
1. The applicability of the human hepatoma cell line, HepG2, as a cell culture model for studying xenobiotic liver toxicity has been investigated using the well-characterized hepatotoxic chemical, bromobenzene. 2. Bromobenzene caused a concentration- (0-10 mM) and time-dependent (0-180 min) decrease in HepG2 cell viability. The degree of toxicity was dependent upon the culture medium composition and the state of cell growth. Toxicity in Modified Earle's and Williams' E Media was maximal at 7 days growth compared with 3 and 10 days, and was greater in Williams' than in Earle's medium. Toxicity in Dulbecco's medium was apparent only at 10 days growth and was less than the maximum toxicity in the other media. 3. Bromobenzene was detoxified by epoxide hydrase. The question of metabolic activation by P450 remained unresolved, but any involvement of P450 was by forms not inhibited by ketoconazole. 4. The mechanism of bromobenzene toxicity did not appear to involve lipid peroxidation, depletion of reduced glutathione, calcium-mediated proteolysis or metabolic activation by prostaglandin synthetase, but may have involved direct solvent-induced cell damage. 5. This study demonstrates the potential usefulness of HepG2 cells in toxicity testing and highlights the importance of standardizing culture conditions.
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Affiliation(s)
- S J Duthie
- Department of Biomedical Sciences, University of Aberdeen, Marischal College, UK
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15
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Affiliation(s)
- U Muller-Eberhard
- Department of Pediatrics/Hematology-Oncology, Cornell University Medical College, New York, NY 10021
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16
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Abstract
Porphyrin accumulation by proliferating cells, e.g., those associated with cancers or wounds, tends to correlate with increased transferrin receptor density. To determine whether transferrin might be implicated in porphyrin transport, fluorescence and absorption spectroscopy were used to study the interaction of porphyrins with transferrin. A single high-affinity binding site for heme and other porphyrins (Kd approximately 20-25 nM) was detected by fluorescence spectroscopy. Difference spectroscopy revealed three additional heme-binding sites. These sites were distinct from the iron-binding sites: 1) Apotransferrin and diferric transferrin bound porphyrins with equal affinity; 2) 59Fe was not displaced from transferrin by porphyrins. Murine erythroleukemia cells incubated with [59Fe]hemin-[125I]transferrin internalized both labels concomitantly. Accumulation of [59Fe]hemin could be blocked by a 100-fold excess of diferric transferrin but not by apotransferrin. These results indicate that cells can internalize exogenous heme, and possibly porphyrins, bound to transferrin via its receptor.
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Affiliation(s)
- D L Stout
- Department of Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston 77030
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