scholarly journals Enhancement of iron toxicity in L929 cells by d-glucose: accelerated(re-)reduction

2002 ◽  
Vol 368 (2) ◽  
pp. 517-526 ◽  
Author(s):  
Ilka LEHNEN-BEYEL ◽  
Herbert de GROOT ◽  
Ursula RAUEN
Keyword(s):  
Ethyl Ester ◽  
Iron Reduction ◽  
Cell Damage ◽  
Reduction Rate ◽  
Fold Increase ◽  
Iron Complex ◽  
Iron Toxicity ◽  
Intracellular Iron ◽  
Iron Valence ◽  
Iron Pool

It has recently been shown that an increase in the cellular chelatable iron pool is sufficient to cause cell damage. To further characterize this kind of injury, we artificially enhanced the chelatable iron pool in L929 mouse fibroblasts using the highly membrane-permeable complex Fe(III)/8-hydroxyquinoline. This iron complex induced a significant oxygen-dependent loss of viability during an incubation period of 5h. Surprisingly, the addition of d-glucose strongly enhanced this toxicity whereas no such effect was exerted by l-glucose and 2-deoxyglucose. The assumption that this increase in toxicity might be due to an enhanced availability of reducing equivalents formed during the metabolism of d-glucose was supported by NAD(P)H measurements which showed a 1.5—2-fold increase in the cellular NAD(P)H content upon addition of d-glucose. To assess the influence of this enhanced cellular reducing capacity on iron valence we established a new method to measure the reduction rate of iron based on the fluorescent iron(II) indicator PhenGreen SK. We could show that the rate of intracellular iron reduction was more than doubled in the presence of d-glucose. A similar acceleration was achieved by adding the reducing agents ascorbate and glutathione (the latter as membrane-permeable ethyl ester). Glutathione ethyl ester, as well as the thiol reagent N-acetylcysteine, also caused a toxicity increase comparable with d-glucose. These results suggest an enhancement of iron toxicity by d-glucose via an accelerated (re-)reduction of iron with NAD(P)H serving as central electron provider and ascorbate, glutathione or possibly NAD(P)H itself as final reducing agent.

scholarly journals Sodium Nitroprusside Promotes IRP2 Degradation via an Increase in Intracellular Iron and in the Absence of S Nitrosylation at C178

2006 ◽  
Vol 26 (5) ◽  
pp. 1948-1954 ◽  
Author(s):  
Jian Wang ◽  
Carine Fillebeen ◽  
Guohua Chen ◽  
Bill Andriopoulos ◽  
Kostas Pantopoulos
Keyword(s):  
Sodium Nitroprusside ◽  
Rna Binding ◽  
Fold Increase ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Similar Response ◽  
Intracellular Iron ◽  
Labile Iron Pool ◽  
Mechanistic Basis ◽  
Iron Pool

ABSTRACT In iron-replete cells the posttranscriptional regulator IRP2 undergoes ubiquitination and proteasomal degradation. A similar response occurs in cells exposed to sodium nitroprusside (SNP), an NO-releasing drug. It has been proposed that nitroprusside ([Fe(CN)5NO]2−) fails to donate iron into cells and that it promotes IRP2 degradation via S nitrosylation at C178. This residue is located within a stretch of 73 amino acids, earlier proposed to define an iron-dependent degradation domain. Surprisingly, we show that IRP2 bearing a C178S mutation or a Δ73 deletion is sensitive to degradation not only by ferric ammonium citrate (FAC) but also by SNP. Moreover, FAC and SNP attenuate the RNA-binding activities of IRP2 and its homologue IRP1 with similar kinetics. Actinomycin D, cycloheximide, succinylacetone, and dimethyl-oxalylglycine antagonize IRP2 degradation in response to both FAC and SNP, suggesting a common mechanistic basis. IRP2 is not only sensitive to fresh, but also to photodegraded SNP and remains unaffected by S-nitrosoglutathione (GSNO), an established nitrosation agent. Importantly, both fresh and photodegraded SNP, but not GSNO, promote a >4-fold increase in the calcein-accessible labile iron pool. Collectively, these results suggest that IRP2 degradation by SNP does not require S nitrosylation but rather represents a response to iron loading.

scholarly journals Effects of Carbon Addition on Dissimilatory Fe(III) Reduction in Freshwater Marsh and Meadow Wetlands

2018 ◽  
Vol 10 (11) ◽  
pp. 4309 ◽  
Author(s):  
Xiaoyan Zhu ◽  
Yuxiang Yuan ◽  
Ming Jiang
Keyword(s):  
Iron Reduction ◽  
Reduction Rate ◽  
Negative Relationship ◽  
Sanjiang Plain ◽  
Freshwater Marsh ◽  
Freshwater Wetlands ◽  
Natural Environments ◽  
Carbon Addition ◽  
Soil Slurry ◽  
The Sanjiang Plain

The progress of dissimilatory iron(III) reduction is widespread in natural environments, particularly in anoxic habitats; in fact, wetland ecosystems are considered as “hotspots” of dissimilatory Fe(III) reduction. In this study, we conducted soil slurry and microbial inoculation anaerobic incubation with glucose, pyruvate, and soluble quinone anthraquinone-2,6-disulphonate (AQDS) additions in freshwater marsh and meadow wetlands in the Sanjiang Plain, to evaluate the role of carbon addition in the rates and dynamics of iron reduction. Dissimilatory Fe(III) reduction in marsh wetlands responded more quickly and showed twice the potential for Fe(III) reduction as that in meadow wetland. Fe(III) reduction rate in marsh and meadow wetlands was 76% and 30%, respectively. Glucose had a higher capacity to enhance Fe(III) reduction than pyruvate, which provides valuable information for the further isolation of Fe reduction bacteria in pure culture. AQDS could dramatically increase potential Fe(III) reduction as an electron shuttle in both wetlands. pH exhibited a negative relationship with Fe(III) reduction. In view of the significance of freshwater wetlands in the global carbon and iron cycle, further profound research is now essential and should explore the enzymatic mechanisms underlying iron reduction in freshwater wetlands.

scholarly journals During Oxidative Stress the Clp Proteins of Escherichia coli Ensure that Iron Pools Remain Sufficient To Reactivate Oxidized Metalloenzymes

2020 ◽  
Vol 202 (18) ◽  
Author(s):  
Ananya Sen ◽  
Yidan Zhou ◽  
James A. Imlay
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Acid Synthesis ◽  
Growth Defect ◽  
Natural Environments ◽  
Intracellular Iron ◽  
Amino Acid Synthesis ◽  
Common Component ◽  
Content Type ◽  
Iron Pool

ABSTRACT Hydrogen peroxide (H2O2) is formed in natural environments by both biotic and abiotic processes. It easily enters the cytoplasms of microorganisms, where it can disrupt growth by inactivating iron-dependent enzymes. It also reacts with the intracellular iron pool, generating hydroxyl radicals that can lethally damage DNA. Therefore, virtually all bacteria possess H2O2-responsive transcription factors that control defensive regulons. These typically include catalases and peroxidases that scavenge H2O2. Another common component is the miniferritin Dps, which sequesters loose iron and thereby suppresses hydroxyl-radical formation. In this study, we determined that Escherichia coli also induces the ClpS and ClpA proteins of the ClpSAP protease complex. Mutants that lack this protease, plus its partner, ClpXP protease, cannot grow when H2O2 levels rise. The growth defect was traced to the inactivity of dehydratases in the pathway of branched-chain amino acid synthesis. These enzymes rely on a solvent-exposed [4Fe-4S] cluster that H2O2 degrades. In a typical cell the cluster is continuously repaired, but in the clpSA clpX mutant the repair process is defective. We determined that this disability is due to an excessively small iron pool, apparently due to the oversequestration of iron by Dps. Dps was previously identified as a substrate of both the ClpSAP and ClpXP proteases, and in their absence its levels are unusually high. The implication is that the stress response to H2O2 has evolved to strike a careful balance, diminishing iron pools enough to protect the DNA but keeping them substantial enough that critical iron-dependent enzymes can be repaired. IMPORTANCE Hydrogen peroxide mediates the toxicity of phagocytes, lactic acid bacteria, redox-cycling antibiotics, and photochemistry. The underlying mechanisms all involve its reaction with iron atoms, whether in enzymes or on the surface of DNA. Accordingly, when bacteria perceive toxic H2O2, they activate defensive tactics that are focused on iron metabolism. In this study, we identify a conundrum: DNA is best protected by the removal of iron from the cytoplasm, but this action impairs the ability of the cell to reactivate its iron-dependent enzymes. The actions of the Clp proteins appear to hedge against the oversequestration of iron by the miniferritin Dps. This buffering effect is important, because E. coli seeks not just to survive H2O2 but to grow in its presence.

scholarly journals Liproxstatin-1 Protects Hair Cell-Like HEI-OC1 Cells and Cochlear Hair Cells against Neomycin Ototoxicity

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Zhiwei Zheng ◽  
Dongmei Tang ◽  
Liping Zhao ◽  
Wen Li ◽  
Jinghong Han ◽  
...  
Keyword(s):  
Hair Cell ◽  
Cell Damage ◽  
Clinical Intervention ◽  
Lipid Peroxides ◽  
Cell Loss ◽  
Neonatal Mouse ◽  
Ros Generation ◽  
Intracellular Iron ◽  
Cochlear Hair Cells ◽  
Dependent Form

Ferroptosis is a recently discovered iron-dependent form of oxidative programmed cell death distinct from caspase-dependent apoptosis. In this study, we investigated the effect of ferroptosis in neomycin-induced hair cell loss by using selective ferroptosis inhibitor liproxstatin-1 (Lip-1). Cell viability was identified by CCK8 assay. The levels of reactive oxygen species (ROS) were determined by DCFH-DA and cellROX green staining. The mitochondrial membrane potential ( Δ Ψ m ) was evaluated by TMRM staining. Intracellular iron and lipid peroxides were detected with Mito-FerroGreen and Liperfluo probes. We found that ferroptosis can be induced in both HEI-OC1 cells and neonatal mouse cochlear explants, as evidenced by Mito-FerroGreen and Liperfluo staining. Further experiments showed that pretreatment with Lip-1 significantly alleviated neomycin-induced increased ROS generation and disruption in Δ Ψ m in the HEI-OC1 cells. In parallel, Lip-1 significantly attenuated neomycin-induced hair cell damage in neonatal mouse cochlear explants. Collectively, these results suggest a novel mechanism for neomycin-induced ototoxicity and suggest that ferroptosis inhibition may be a new clinical intervention to prevent hearing loss.

scholarly journals RyhB small RNA modulates the free intracellular iron pool and is essential for normal growth during iron limitation in Escherichia coli

2006 ◽  
Vol 62 (4) ◽  
pp. 1181-1190 ◽  
Author(s):  
Jean-François Jacques ◽  
Soojin Jang ◽  
Karine Prévost ◽  
Guillaume Desnoyers ◽  
Maxime Desmarais ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Small Rna ◽  
Normal Growth ◽  
Iron Limitation ◽  
Intracellular Iron ◽  
Iron Pool

Susceptibility of Endocrine, Cardiac, and Macrophage Cell Lines to Iron-Mediated Oxidative Damage and the Cytoprotective Effect of the Orally Active Chelator Deferasirox (Exjade®, ICL670).

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3825-3825
Author(s):  
Hava Glickstein ◽  
Hanspeter Nick ◽  
Zvi I. Cabantchik
Keyword(s):  
Cell Viability ◽  
Cell Damage ◽  
Experimental Testing ◽  
Cardiac Cells ◽  
Binding Property ◽  
Iron Loading ◽  
Cytoprotective Effect ◽  
Intracellular Iron ◽  
Labile Iron

Abstract Systemic iron overload (primary or secondary) affects hepatic and extrahepatic functions by damaging endocrine and cardiac tissue. In vitro studies with pancreatic Min6 and pituitary Att20 cells and with cardiac H9c2 cells (all highly active in endocytotic activity) indicated that their exposure to labile iron, acutely or chronically, lead to major intracellular iron accumulation in organelles (endosomes, mitochondria, cytosol) and increased reactive oxygen species (ROS) formation when redox challenged. Among the functions affected by metal-evoked ROS are permselectivity (calcein leakage), mitochondrial ΔΨ (JC1 test), electron transport activity (Alamar Blue) and cell viability (calcein-propidium iodide). The administration at therapeutically achievable doses of deferasirox (30–100 μM) or deferoxamine (DFO) [10 μM] largely (>70%) prevented labile iron from rising in cells if present in the iron-loading medium; however, only deferasirox reduced iron-evoked cell damage and increased cell viability if incubated with cells prior to or post iron-loading (acute or chronic). Thus, deferasirox has both preventive and corrective potential against iron-evoked damage in iron-loaded endocrine and cardiac cells. A gradual reduction of serum concentration from 10% (normally used in culture conditions) to 1% or less (used for experimental testing of drugs) revealed a commensurate increased susceptibility of endocrine and cardiac cells to deferasirox in the higher concentration range of 50–100 μM (48–72 cell viability test). This indicates that the plasma-binding property of deferasirox has a cytoprotective effect.

scholarly journals The 58-Kilodalton Major Virulence Factor of Francisella tularensis Is Required for Efficient Utilization of Iron

2009 ◽  
Vol 77 (10) ◽  
pp. 4429-4436 ◽  
Author(s):  
Helena Lindgren ◽  
Marie Honn ◽  
Igor Golovlev ◽  
Konstantin Kadzhaev ◽  
Wayne Conlan ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Iron Acquisition ◽  
Protein A ◽  
Intracellular Iron ◽  
Major Virulence Factor ◽  
Iron Pool ◽  
Isogenic Mutants ◽  
Schu S4 ◽  
Iron Concentrations

ABSTRACT We investigated the role of the 58-kDa FTT0918 protein in the iron metabolism of Francisella tularensis. The phenotypes of SCHU S4, a prototypic strain of F. tularensis subsp. tularensis, and the ΔFTT0918 and ΔfslA isogenic mutants were analyzed. The gene product missing in the ΔfslA mutant is responsible for synthesis of a siderophore. When grown in broth with various iron concentrations, the two deletion mutants generally reached lower maximal densities than SCHU S4. The ΔFTT0918 mutant, but not the ΔfslA mutant, upregulated the genes of the F. tularensis siderophore locus (fsl) operon even at high iron concentrations. A chrome azurol sulfonate plate assay confirmed siderophore production by all strains except the ΔfslA strain. In a cross-feeding experiment using medium devoid of free iron, SCHU S4 promoted growth of the ΔfslA strain but not of the ΔFTT0918 strain. The sensitivity of SCHU S4 and the ΔFTT0918 and ΔfslA strains to streptonigrin demonstrated that the ΔFTT0918 strain contained a smaller free intracellular iron pool and that the ΔfslA strain contained a larger one than SCHU S4. In contrast to the marked attenuation of the ΔFTT0918 strain, the ΔfslA strain was as virulent as SCHU S4 in a mouse model. Altogether, the data demonstrate that the FTT0918 protein is required for F. tularensis to utilize iron bound to siderophores and that it likely has a role also in siderophore-independent iron acquisition. We suggest that the FTT0918 protein be designated Fe utilization protein A, FupA.

scholarly journals Mitochondria have Fe(III) receptors

1990 ◽  
Vol 265 (2) ◽  
pp. 415-419 ◽  
Author(s):  
J Weaver ◽  
H Zhan ◽  
S Pollack
Keyword(s):  
Recent Work ◽  
Iron Complex ◽  
Major Constituent ◽  
High Affinity ◽  
Saturable Binding ◽  
Iron Pool ◽  
New Evidence ◽  
Binding To Mitochondria

Recent work has provided new evidence that ATP is the major constituent of the low-Mr iron pool in the reticulocyte. The interaction of the iron complex of ATP with mitochondria was investigated in the present experiments. When ATP-Fe3+ was incubated with mitochondria, Fe3+, free of ATP, bound with high affinity to Fe3+ receptors on the mitochondria. The binding was saturable and reversible. Iron which was complexed to PPi, nitrilotriacetate, citrate, ADP and GTP also showed saturable binding to mitochondria; Fe3+ complexed to AMP bound non-specifically, as did Fe2+/ascorbate complexed to AMP bound non-specifically, as did Fe2+/ascorbate and Fe2+/dithionite.

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