Repression of ferritin expression increases the labile iron pool, oxidative stress, and short-term growth of human erythroleukemia cells

Blood ◽  
2001 ◽  
Vol 97 (9) ◽  
pp. 2863-2871 ◽  
Author(s):  
Or Kakhlon ◽  
Yosef Gruenbaum ◽  
Zvi Ioav Cabantchik
Keyword(s):  
Protein Expression ◽  
Protein Oxidation ◽  
Day Treatment ◽  
K562 Cells ◽  
Growth Stimulation ◽  
Labile Iron Pool ◽  
Protein Levels ◽  
Ferritin Synthesis ◽  
Labile Iron ◽  
Iron Pool

Abstract The role of ferritin expression on the labile iron pool of cells and its implications for the control of cell proliferation were assessed. Antisense oligodeoxynucleotides were used as tools for modulating the expression of heavy and light ferritin subunits of K562 cells. mRNA and protein levels of each subunit were markedly reduced by 2-day treatment with antisense probes against the respective subunit. Although the combined action of antisense probes against both subunits reduced their protein expression, antisense repression of one subunit led to an increased protein expression of the other. Antisense treatment led to a rise in the steady-state labile iron pool, a rise in the production of reactive oxygen species after pro-oxidative challenges and in protein oxidation, and the down-regulation of transferrin receptors. When compared to the repression of individual subunits, co-repression of each subunit evoked a more than additive increase in the labile iron pool and the extent of protein oxidation. These treatments had no detectable effects on the long-term growth of cells. However, repression of ferritin synthesis facilitated the renewal of growth and the proliferation of cells pre-arrested at the G1/S phase. Renewed cell growth was significantly less dependent on external iron supply when ferritin synthesis was repressed and its degradation inhibited by lysosomal antiproteases. This study provides experimental evidence that links the effect of ferritin repression on growth stimulation to the expansion of the labile iron pool.

The Cellular Labile Iron Pool and Intracellular Ferritin in K562 Cells

Blood ◽  
1999 ◽  
Vol 94 (6) ◽  
pp. 2128-2134 ◽  
Author(s):  
Abraham M. Konijn ◽  
Hava Glickstein ◽  
Boris Vaisman ◽  
Esther G. Meyron-Holtz ◽  
Itzchak N. Slotki ◽  
...  
Keyword(s):  
Biological Effects ◽  
Ferritin Level ◽  
Regulatory Protein ◽  
Iron Chelation ◽  
K562 Cells ◽  
Iron Chelator ◽  
Labile Iron Pool ◽  
Cellular Iron ◽  
Labile Iron ◽  
Iron Pool

Abstract The labile iron pool (LIP) harbors the metabolically active and regulatory forms of cellular iron. We assessed the role of intracellular ferritin in the maintenance of intracellular LIP levels. Treating K562 cells with the permeant chelator isonicotinoyl salicylaldehyde hydrazone reduced the LIP from 0.8 to 0.2 μmol/L, as monitored by the metalo-sensing probe calcein. When cells were reincubated in serum-free and chelator-free medium, the LIP partially recovered in a complex pattern. The first component of the LIP to reappear was relatively small and occurred within 1 hour, whereas the second was larger and relatively slow to occur, paralleling the decline in intracellular ferritin level (t½= 8 hours). Protease inhibitors such as leupeptin suppressed both the changes in ferritin levels and cellular LIP recovery after chelation. The changes in the LIP were also inversely reflected in the activity of iron regulatory protein (IRP). The 2 ferritin subunits, H and L, behaved qualitatively similarly in response to long-term treatments with the iron chelator deferoxamine, although L-ferritin declined more rapidly, resulting in a 4-fold higher H/L-ferritin ratio. The decline in L-ferritin, but not H-ferritin, was partially attenuated by the lysosomotrophic agent, chloroquine; on the other hand, antiproteases inhibited the degradation of both subunits to the same extent. These findings indicate that, after acute LIP depletion with fast-acting chelators, iron can be mobilized into the LIP from intracellular sources. The underlying mechanisms can be kinetically analyzed into components associated with fast release from accessible cellular sources and slow release from cytosolic ferritin via proteolysis. Because these iron forms are known to be redox-active, our studies are important for understanding the biological effects of cellular iron chelation.

scholarly journals Repression of the heavy ferritin chain increases the labile iron pool of human K562 cells

2001 ◽  
Vol 356 (2) ◽  
pp. 311 ◽  
Author(s):  
Or KAKHLON ◽  
Yosef GRUENBAUM ◽  
Z. Ioav CABANTCHIK
Keyword(s):  
K562 Cells ◽  
Labile Iron Pool ◽  
Labile Iron ◽  
Iron Pool

scholarly journals The Action of JAK/STAT3 and BMP/HJV/SMAD Signaling Pathways on Hepcidin Suppression by Tucum-do-Cerrado in a Normal and Iron-Enriched Diets

Nutrients ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1515
Author(s):  
Sandra Fernandes Arruda ◽  
Larissa Valadares Ramos ◽  
Júlia Lima de Alencar Barbosa ◽  
Natália Aboudib Campos Hankins ◽  
Pedro Augusto Matos Rodrigues ◽  
...  
Keyword(s):  
Control Diet ◽  
Mrna Levels ◽  
Hepcidin Expression ◽  
Excess Iron ◽  
Labile Iron Pool ◽  
Protein Levels ◽  
Chelating Activity ◽  
Tissue Iron ◽  
Labile Iron ◽  
Iron Pool

The Brazilian savanna fruit, tucum-do-cerrado (Bactris setosa Mart.) reduces hepatic hepcidin levels. Therefore, we investigated the effect of tucum-do-cerrado on the TfR/HFE and/or BMP/HJV/SMAD and JAK/STAT pathways, in normal and excess iron conditions. Rats were treated with: control diet (CT); control diet +15% tucum-do-cerrado (Tuc); iron-enriched diet (+Fe); or iron-enriched diet +15% tucum-do-cerrado (Tuc+Fe). Tucum-do-cerrado (Tuc) decreased hepatic Hamp and Hjv mRNA levels but did not alter Bmp6, Smad7, Tfr1, and Hfe mRNA levels; pSMAD1/5/8 and pSTAT3 protein levels; labile iron pool (LIP); and inflammatory biomarkers, compared to the CT group. The iron-enriched diet increased Hamp mRNA levels, as well as pSMAD1/5/8 and pSTAT3 protein levels, while no difference was observed in Hjv, Bmp6, Smad7, Tfr1, and Hfe mRNA levels and LIP compared to the CT group. The association of tucum-do-cerrado with the iron-enriched diet (Tuc+Fe) decreased Hamp, Hjv, Bmp6, and Hfe mRNA levels and pSTAT3 protein content compared to the +Fe group, while increased Hamp and decreased Hfe mRNA levels compared to the Tuc group. Therefore, the inhibition of hepatic hepcidin by tucum-do-cerrado consumption may involve the downregulation of intestinal Dmt1 and hepatic Hjv expression and deacetylation mediated by SIRT1 by a mechanism that is independent of tissue iron content. However, in excess iron conditions, the modulation of hepatic hepcidin expression by tucum-do-cerrado seems to be partially mediated by the inflammatory signaling pathway, as well as involves the chelating activity of tucum-do-cerrado.

Repression of the heavy ferritin chain increases the labile iron pool of human K562 cells

2001 ◽  
Vol 356 (2) ◽  
pp. 311-316 ◽  
Author(s):  
Or KAKHLON ◽  
Yosef GRUENBAUM ◽  
Z. Ioav CABANTCHIK
Keyword(s):  
K562 Cells ◽  
Transferrin Receptors ◽  
Labile Iron Pool ◽  
Labile Iron ◽  
Iron Pool ◽  
Antisense Construct

The role of ferritin in the modulation of the labile iron pool was examined by repressing the heavy subunit of ferritin in K562 cells transfected with an antisense construct. Repression of the heavy ferritin subunit evoked an increase in the chemical levels and pro-oxidant activity of the labile iron pool and, in turn, caused a reduced expression of transferrin receptors and increased expression of the light ferritin subunit

Ferritin expression modulates cell cycle dynamics and cell responsiveness to H-ras-induced growth via expansion of the labile iron pool

2002 ◽  
Vol 363 (3) ◽  
pp. 431-436 ◽  
Author(s):  
Or KAKHLON ◽  
Yosef GRUENBAUM ◽  
Z. Ioav CABANTCHIK
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Growth Arrest ◽  
Growth Stimulation ◽  
Dominant Negative ◽  
Labile Iron Pool ◽  
Labile Iron ◽  
Cell Cycling ◽  
Iron Pool ◽  
Cell Cycle Dynamics

Repression or overexpression of ferritin accelerated or retarded cell cycling respectively, via changes in the cellular labile iron pool (LIP). A rise in LIP is caused by ferritin repression enhanced growth, induced by H-ras, and reverted growth arrest is induced by dominant negative H-ras. The studies indicate that repression of ferritin expression provides a mechanism by which certain oncogenes lead to cell growth stimulation.

The Cellular Labile Iron Pool and Intracellular Ferritin in K562 Cells

Blood ◽  
1999 ◽  
Vol 94 (6) ◽  
pp. 2128-2134 ◽  
Author(s):  
Abraham M. Konijn ◽  
Hava Glickstein ◽  
Boris Vaisman ◽  
Esther G. Meyron-Holtz ◽  
Itzchak N. Slotki ◽  
...  
Keyword(s):  
Biological Effects ◽  
Ferritin Level ◽  
Regulatory Protein ◽  
Iron Chelation ◽  
K562 Cells ◽  
Iron Chelator ◽  
Labile Iron Pool ◽  
Cellular Iron ◽  
Labile Iron ◽  
Iron Pool

The labile iron pool (LIP) harbors the metabolically active and regulatory forms of cellular iron. We assessed the role of intracellular ferritin in the maintenance of intracellular LIP levels. Treating K562 cells with the permeant chelator isonicotinoyl salicylaldehyde hydrazone reduced the LIP from 0.8 to 0.2 μmol/L, as monitored by the metalo-sensing probe calcein. When cells were reincubated in serum-free and chelator-free medium, the LIP partially recovered in a complex pattern. The first component of the LIP to reappear was relatively small and occurred within 1 hour, whereas the second was larger and relatively slow to occur, paralleling the decline in intracellular ferritin level (t½= 8 hours). Protease inhibitors such as leupeptin suppressed both the changes in ferritin levels and cellular LIP recovery after chelation. The changes in the LIP were also inversely reflected in the activity of iron regulatory protein (IRP). The 2 ferritin subunits, H and L, behaved qualitatively similarly in response to long-term treatments with the iron chelator deferoxamine, although L-ferritin declined more rapidly, resulting in a 4-fold higher H/L-ferritin ratio. The decline in L-ferritin, but not H-ferritin, was partially attenuated by the lysosomotrophic agent, chloroquine; on the other hand, antiproteases inhibited the degradation of both subunits to the same extent. These findings indicate that, after acute LIP depletion with fast-acting chelators, iron can be mobilized into the LIP from intracellular sources. The underlying mechanisms can be kinetically analyzed into components associated with fast release from accessible cellular sources and slow release from cytosolic ferritin via proteolysis. Because these iron forms are known to be redox-active, our studies are important for understanding the biological effects of cellular iron chelation.

scholarly journals Analysis of yggX and gshA Mutants Provides Insights into the Labile Iron Pool in Salmonella enterica

2008 ◽  
Vol 190 (23) ◽  
pp. 7608-7613 ◽  
Author(s):  
Michael P. Thorgersen ◽  
Diana M. Downs
Keyword(s):  
Salmonella Enterica ◽  
Iron Chelator ◽  
Fenton Chemistry ◽  
Labile Iron Pool ◽  
Growth Defects ◽  
Labile Iron ◽  
Iron Pool ◽  
Mutant Phenotypes ◽  
Permeable Iron ◽  
Iron Chelator Deferoxamine

ABSTRACT Strains of Salmonella enterica lacking YggX and the cellular reductant glutathione exhibit defects similar to those resulting from iron deficiency and oxidative stress. Mutant strains are sensitive to hydrogen peroxide and superoxide, deregulate the expression of the Fur-regulated gene entB, and fail to grow on succinate medium. Suppression of some yggX gshA mutant phenotypes by the cell-permeable iron chelator deferoxamine allowed the conclusion that increased levels of cellular Fenton chemistry played a role in the growth defects. The data presented are consistent with a scenario in which glutathione acts as a physiological chelator of the labile iron pool and in which YggX acts upstream of the labile iron pool by preventing superoxide toxicity.

scholarly journals Labile iron pool correlates with iron content in the nucleus and the formation of oxidative DNA damage in mouse lymphoma L5178Y cell lines.

2003 ◽  
Vol 50 (1) ◽  
pp. 211-215 ◽  
Author(s):  
Marcin Kruszewski ◽  
Teresa Iwaneńko
Keyword(s):  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Cell Lines ◽  
Oxidative Dna Damage ◽  
Transition Metal Ions ◽  
Dna Lesions ◽  
Labile Iron Pool ◽  
Labile Iron ◽  
Iron Pool ◽  
Mouse Lymphoma

Labile iron pool (LIP) constitutes a crossroad of metabolic pathways of iron-containing compounds and is midway between the cellular need for iron, its uptake and storage. In this study we investigated oxidative DNA damage in relation to the labile iron pool in a pair of mouse lymphoma L5178Y (LY) sublines (LY-R and LY-S) differing in sensitivity to hydrogen peroxide. The LY-R cells, which are hydrogen peroxide-sensitive, contain 3 times more labile iron than the hydrogen peroxide-resistant LY-S cells. Using the comet assay, we compared total DNA breakage in the studied cell lines treated with hydrogen peroxide (25 microM for 30 min at 4 degrees C). More DNA damage was found in LY-R cells than in LY-S cells. We also compared the levels of DNA lesions sensitive to specific DNA repair enzymes in both cell lines treated with H(2)O(2). The levels of endonuclease III-sensitive sites and Fapy-DNA glycosylase-sensitive sites were found to be higher in LY-R cells than in LY-S cells. Our data suggest that the sensitivity of LY-R cells to H(2)O(2) is partially caused by the higher yield of oxidative DNA damage, as compared to that in LY-S cells. The critical factor appears to be the availability of transition metal ions that take part in the OH radical-generating Fenton reaction (very likely in the form of LIP).

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