Iron metabolism of established human hematopoietic cell lines in vitro*1

Forsbeck, Klas; Nilsson, Kenneth

doi:10.1016/0014-4827(83)90411-1

Cited by 21 publications

(15 citation statements)

References 33 publications

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“…Similar activity has been noted in a number of other cell types, including mammalian endothelial cells and macrophages (4,6,21,25,27,28,30,40,43,52). Previous work has shown that CQ treatment can alter vacuolar pH in yeast (42).…”

Section: Discussionsupporting

confidence: 66%

Relationship between Chloroquine Toxicity and Iron Acquisition in Saccharomyces cerevisiae

Emerson

Nau

Martin³

et al. 2002

Antimicrob Agents Chemother

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Chloroquine is one of the most effective antimalarials, but resistance to it is becoming widespread. However, we do not fully understand either the drug's mode of action or the mechanism of resistance. In an effort to expand our understanding of the mechanism of action and resistance associated with chloroquine, we used Saccharomyces cerevisiae as a model eukaryotic system. To aid in the discovery of potential drug targets we applied the transcriptional profiling method to identify genes transcriptionally responsive to chloroquine treatment in S. cerevisiae. Among the genes that were differentially expressed with chloroquine treatment were a number of metal transporters involved in iron acquisition (SIT1, ARN2, ARN4, and SMF2). These genes exhibit similar expression patterns, and several are known to be regulated by AFT1, a DNA binding protein, which responds to iron levels in the cell. We investigated the role of chloroquine in iron metabolism by using a variety of approaches, including pharmacological, genetic, and biochemical techniques. For these experiments, we utilized yeast lacking the major iron uptake pathways (FET3 and FET4) and yeast deficient in SIT1, encoding the major up-regulated iron siderophore transporter. Our experiments show that yeast genetically or environmentally limited in iron availability has increased sensitivity to chloroquine in pharmacological assays and that the addition of iron rescues these cells from chloroquine killing.55 FeCl 3 accumulation was inhibited in the presence of chloroquine, and kinetic analysis demonstrated that inhibition was competitive. These results are consistent with deprivation of iron as a mechanism of chloroquine killing in yeast.Chloroquine (CQ) is commonly used for treatment of malaria; however, its mode of action and the mechanism of resistance are still not fully understood. Better knowledge of CQ's mode of action may make it possible to identify new drugs that target similar pathways or to reverse existing resistant phenotypes.CQ has been shown to interact in both mammalian cells and Plasmodium spp. with a number of different pathways, including changes in vacuolar (or lysosomal) pH (9,22,39,56), binding to DNA and RNA (3,11,41,53), binding to heme and ␤-hematin in Plasmodium falciparum (1, 55; reviewed in reference 20). In the case of P. falciparum, CQ was an effective drug whose efficacy has been severely compromised by the emergence of drug-resistant parasites (8,20).To analyze the mechanism of CQ action, we used transcriptional profiling in a model eukaryotic system, Saccharomyces cerevisiae. Differential transcriptional profiling using microarray analysis is based on detecting differences in expression of mRNAs in cells treated under different conditions. No information other than the genomic sequence and the open reading frame (ORF) predictions is necessary to assay mRNA expression. Such whole-genome analysis allows the determination of expression profiles without preselection of genes. For the experiments described here, we used the Affymetrix...

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Section: Discussionsupporting

confidence: 66%

Relationship between Chloroquine Toxicity and Iron Acquisition in Saccharomyces cerevisiae

Emerson

Nau

Martin³

et al. 2002

Antimicrob Agents Chemother

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“…Thus, coculture of H. capsulatum-infected M with DEF suppresses the growth of the yeast cells, an effect that is reversed by holotransferrin, confirming the studies in murine M. In addition, chloroquine, a weak base that prevents the release of iron from transferrin by raising endocytic and lysosomal pH (2,18,24,44), induces human M to kill H. capsulatum. The effect of chloroquine is reversed by iron nitriloacetate (FeNTA), an iron compound that is soluble at neutral to alkaline pH (1), but not by holotransferrin, which releases iron only in an acidic environment.…”

supporting

confidence: 72%

“…We have demonstrated that restriction of the availability of intracellular iron induces human M to kill H. capsulatum yeast cells (35). These studies used both DEF, an iron chelator, and chloroquine, a weak base, which restricted the availability of iron by raising the intraphagosomal pH (2,18,24,44). The results also indicated that the hydroxamic acid siderophores of H. capsulatum cannot scavenge iron from DEF or transferrin and that intracellular iron must be free to be utilized by H. capsulatum yeast cells.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of growth of Histoplasma capsulatum yeast cells in human macrophages by the iron chelator VUF 8514 and comparison of VUF 8514 with deferoxamine

Newman

Gootee

Stroobant

et al. 1995

Antimicrob Agents Chemother

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Histoplasma capsulatum requires intracellular iron to survive and multiply within human and murine macrophages (M). Thus, iron chelators may be useful compounds in the treatment of histoplasmosis. In the present study we compared the efficacies of five different iron chelators with deferoxamine (DEF) for their capacity to inhibit the growth of H. capsulatum yeast cells in culture medium and within human M. Of the agents tested, only one, VUF 8514, a 2,2-bipyridyl analog, was found to be effective. VUF 8514 inhibited the growth of yeast cells in tissue culture medium and within M in a dose-response fashion. In tissue culture medium, the 50% effective dose (ED 50 ) of VUF 8514 was 30 nM and the ED 50 of DEF was 1 mM. In human M, the ED 50 of VUF 8514 was 520 nM and the ED 50 of DEF was 4 mM. Thus, VUF 8514 was effective at a concentration 7.7 ؋ 10 The mechanism used by Histoplasma capsulatum yeast cells to survive and multiply within human macrophages (M) are poorly understood. Phagocytosis of H. capsulatum yeast cells by human monocyte/M stimulates both the respiratory burst (6, 33, 39) and phagolysosomal fusion (37). Nevertheless, ingested yeast cells multiply within M phagolysosomes (17,34,36).Original studies on the interaction of H. capsulatum yeast cells with murine peritoneal M suggest that acquisition of intracellular iron may be important for yeast survival. Thus, coculture of H. capsulatum-infected murine peritoneal M in the presence of the iron chelator deferoxamine (DEF) suppresses the intracellular growth of yeast cells, and this effect is reversed by iron-saturated transferrin (holotransferrin) (25). More important, one mechanism by which gamma interferonactivated mouse peritoneal M (25) and gamma interferonlipopolysaccharide-activated murine splenic M (26) inhibit the intracellular growth of H. capsulatum is by the restriction of intracellular iron.Even though gamma interferon does not activate the antifungal activity of human M (17, 34), iron is a critical requirement for the intracellular survival of H. capsulatum yeast cells in human M (35). Thus, coculture of H. capsulatum-infected M with DEF suppresses the growth of the yeast cells, an effect that is reversed by holotransferrin, confirming the studies in murine M. In addition, chloroquine, a weak base that prevents the release of iron from transferrin by raising endocytic and lysosomal pH (2,18,24,44), induces human M to kill H. capsulatum. The effect of chloroquine is reversed by iron nitriloacetate (FeNTA), an iron compound that is soluble at neutral to alkaline pH (1), but not by holotransferrin, which releases iron only in an acidic environment. Furthermore, chloroquine is an effective therapeutic agent in a murine model of histoplasmosis (35).These data suggest that agents that interfere with the ability of H. capsulatum yeast cells to acquire intracellular iron may be useful in the treatment of histoplasmosis. Currently, DEF is the only metal chelator that is available for clinical use, and it has been used mainly in patients with hematol...

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“…In contrast, iron that is bound to ferritin is released to the intermediate pool of the cell after ferritin is degraded in lysosomes (37,38). Chloroquine prevents the release of ferric ions from saturated iron transferrin (19)(20)(21)(22) and may prevent degradation of ferritin by acid proteases (39) by virtue of its ability to raise endocytic and lysosomal pH.…”

Section: Discussionmentioning

confidence: 99%

“…Plates were incubated at 30'C, and CFU were counted after 7-lOd (16 diprotic weak base that raises the pH of endocytic vesicles and lysosomes in eukaryotic cells ( 19). It therefore prevents the release of iron from transferrin in a variety ofcell types including MO (19)(20)(21)(22). Byrd and Horwitz ( 13) have shown that chloroquine inhibits the intracellular growth of L. pneumophila in human monocytes and that the effect of chloroquine is reversed by FeNTA, a compound in which iron remains soluble at neutral to alkaline pH (23).…”

mentioning

confidence: 99%

Chloroquine induces human macrophage killing of Histoplasma capsulatum by limiting the availability of intracellular iron and is therapeutic in a murine model of histoplasmosis.

Newman¹,

Gootee²,

Brunner³

et al. 1994

J. Clin. Invest.

128

127

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IntroductionWe investigated the role of intracellular iron on the capacity of Histoplasma capsulatum (Hc) yeasts to multiply within human macrophages (M+). Coculture of Hc-infected MO with the iron chelator deferoxamine suppressed the growth of yeasts in a concentration-dependent manner. The effect of deferoxamine was reversed by iron-saturated transferrin (holotransferrin) but not by iron-free transferrin (apotransferrin). Chloroquine, which prevents release of iron from transferrin by raising endocytic and lysosomal pH, induced human MO to kill Hc. The effect of chloroquine was reversed by iron nitriloacetate, an iron compound that is soluble at neutral to alkaline pH, but not by holotransferrin, which releases iron only in an acidic environment.Chloroquine (40-120 mg/kg) given intraperitoneally for 6 d to Hc-infected C57BL/6 mice significantly reduced the growth of Hc in a dose-dependent manner. At 120 mg/kg there was a 17-and 15-fold reduction (P < 0.01) in CFU in spleens and livers, respectively. The therapeutic effect of chloroquine also correlated with the length of treatment. As little as 2 d of chloroquine therapy (120 mg/kg), when started at day 5 after infection, reduced CFU in the spleen by 50%. Treatment with chloroquine for 10 d after a lethal inoculum of Hc protected six of nine mice; all control mice were dead by day 11 (P = 0.009).This study demonstrates that: (a) iron is of critical importance to the survival and multiplication of Hc yeasts in human MO; (b)

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Iron metabolism of established human hematopoietic cell lines in vitro*1

Cited by 21 publications

References 33 publications

Relationship between Chloroquine Toxicity and Iron Acquisition in Saccharomyces cerevisiae

Relationship between Chloroquine Toxicity and Iron Acquisition in Saccharomyces cerevisiae

Inhibition of growth of Histoplasma capsulatum yeast cells in human macrophages by the iron chelator VUF 8514 and comparison of VUF 8514 with deferoxamine

Chloroquine induces human macrophage killing of Histoplasma capsulatum by limiting the availability of intracellular iron and is therapeutic in a murine model of histoplasmosis.

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