scholarly journals Transferrin receptor expression and the regulation of placental iron uptake

1991 ◽  
Vol 100 (1) ◽  
pp. 31-38 ◽  
Author(s):  
M. B. Bierings ◽  
M. R. M. Baert ◽  
H. G. van Eijk ◽  
J. P. van Dijk
Keyword(s):  
Transferrin Receptor ◽  
Iron Uptake ◽  
Receptor Expression ◽  
Transferrin Receptor Expression

scholarly journals Modulation of iron metabolism in monocyte cell line U937 by inflammatory cytokines: changes in transferrin uptake, iron handling and ferritin mRNA

1993 ◽  
Vol 296 (1) ◽  
pp. 175-181 ◽  
Author(s):  
M Fahmy ◽  
S P Young
Keyword(s):  
Cell Line ◽  
Inflammatory Cytokines ◽  
Iron Metabolism ◽  
Transferrin Receptor ◽  
Iron Uptake ◽  
Interleukin 1 ◽  
Receptor Expression ◽  
Tnf Alpha ◽  
Ifn Gamma ◽  
Transferrin Receptor Expression

We have investigated the effects of the pro-inflammatory cytokines interleukin 1 beta (IL-1 beta), tumour necrosis factor alpha (TNF alpha) and interferon gamma (IFN gamma) on the iron metabolism of the human monocytic cell line U937. Cells were treated with each cytokine for up to 24 h, and then iron uptake from diferric transferrin was determined. The intracellular distribution of this iron, the expression of the transferrin receptor and levels of mRNA for the two ferritin subunits were also studied. IL-1 beta, TNF alpha and IFN gamma all decreased transferrin-iron uptake into cells, and all three cytokines had effects on the proportion of iron associated with ferritin. With TNF alpha there was a marked enhancement of the fraction incorporated into ferritin. Transferrin-receptor expression was diminished by TNF alpha and IL-1 beta, but not IFN gamma, suggesting different effector mechanisms. Both TNF alpha and IFN gamma increased the amount of cellular mRNA for ferritin H-chain, but not the L-chain; IL-1 beta affected mRNA for neither ferritin. These data demonstrate that cytokines, which can be present at high concentrations in inflammation, have the capacity to affect macrophage iron uptake, transferrin receptor expression, intracellular iron handling and the relative abundance of ferritin-subunit mRNA, and may therefore be important mediators in the observed perturbations of iron metabolism in inflammatory diseases.

scholarly journals Effect of aluminium on iron uptake and transferrin-receptor expression by human erythroleukaemia K562 cells

1990 ◽  
Vol 272 (2) ◽  
pp. 377-382 ◽  
Author(s):  
S J McGregor ◽  
M L Naves ◽  
R Oria ◽  
J K Vass ◽  
J H Brock
Keyword(s):  
Transferrin Receptor ◽  
Iron Uptake ◽  
K562 Cells ◽  
Inhibitory Effect ◽  
Receptor Expression ◽  
Transferrin Receptors ◽  
High Concentration ◽  
Intracellular Release ◽  
Aluminium Citrate ◽  
Transferrin Receptor Expression

Incubation of human erythroleukaemia K562 cells with Al-transferrin inhibited iron uptake from 59Fe-transferrin by about 80%. The inhibition was greater than that produced by a similar quantity of Fe-transferrin. Preincubation of cells for 6 h with either Al-transferrin or Fe-transferrin diminished the number of surface transferrin receptors by about 40% compared with cells preincubated with apo-transferrin. Al-transferrin did not compete significantly with Fe-transferrin for transferrin receptors and, when cells were preincubated for 15 min instead of 6 h, the inhibitory effect of Al-transferrin on receptor expression was lost. Both forms of transferrin also decreased the level of transferrin receptor mRNA by about 50%, suggesting a common regulatory mechanism. Aluminium citrate had no effect on iron uptake or transferrin-receptor expression. AlCl3 also had no effect on transferrin-receptor expression, but at high concentration it caused an increase in iron uptake by an unknown, possibly non-specific, mechanism. Neither Al-transferrin nor AlCl3 caused a significant change in cell proliferation. It is proposed that aluminium, when bound to transferrin, inhibits iron uptake partly by down-regulating transferrin-receptor expression and partly by interfering with intracellular release of iron from transferrin.

scholarly journals Ferritin uptake by human erythroid precursors is a regulated iron uptake pathway

Blood ◽  
1996 ◽  
Vol 88 (8) ◽  
pp. 3200-3207 ◽  
Author(s):  
D Gelvan ◽  
E Fibach ◽  
EG Meyron-Holtz ◽  
AM Konijn
Keyword(s):  
Transferrin Receptor ◽  
Iron Uptake ◽  
Iron Status ◽  
Receptor Expression ◽  
Erythroid Precursor ◽  
Cellular Iron ◽  
Uptake Pathway ◽  
Iron Assimilation ◽  
Ferritin Iron ◽  
Transferrin Receptor Expression

Iron delivery to mammalian cells is traditionally ascribed to diferric transferrin (Tf). We recently reported that human erythroid precursor cells possess specific membranes receptors that bind and internalize acid isoferritin. Here we show that ferritin uptake by these cells is highly regulated and that the internalized ferritin-iron is used for home synthesis and thus, this process could constitute a physiological pathway for iron assimilation. Ferritin was internalized by a specific, saturable process, distinct from the uptake of iron associated with albumin. Ferritin uptake downregulated transferrin-receptor expression, indicating that internalized ferritin-iron was recognized as an integral part of the cellular iron content. Ferritin receptor expression was coordinated to cell development and was tightly regulated by cellular iron status. Receptor abundance was increased by iron-depletion and decreased by iron-loading, while the affinity of the ferritin receptor for acid isoferritin remained nearly constant (kd = 4.1 +/- 0.5 x 10(-6) mol/L). Under all experimental conditions, ferritin- and transferrin-receptor expression was closely coordinated, suggesting that these pathways possess a common regulatory element. It is concluded that ferritin uptake by erythroid cells constitutes an iron uptake pathway in addition to the classical transferrin uptake pathway.

scholarly journals Role of transferrin, transferrin receptors, and iron in macrophage listericidal activity.

1991 ◽  
Vol 174 (2) ◽  
pp. 459-466 ◽  
Author(s):  
C E Alford ◽  
T E King ◽  
P A Campbell
Keyword(s):  
Transferrin Receptor ◽  
Iron Uptake ◽  
Free Ligand ◽  
Peritoneal Macrophages ◽  
Receptor Expression ◽  
Intracellular Bacteria ◽  
Intracellular Iron ◽  
Proteose Peptone ◽  
Transferrin Receptor Expression

It is not yet known what properties distinguish macrophages which can kill facultative intracellular bacteria, such as Listeria monocytogenes, from those which cannot. Listeria is an organism which requires iron for growth, yet macrophage listericidal mechanisms are also likely to be iron dependent. We show here that resident peritoneal macrophages and thioglycollate-elicited macrophages cannot kill listeria, but proteose peptone-elicited and FCS-elicited macrophages can. All these cell populations phagocytose listeria. Transferrin receptor expression is low on resident cells, intermediate on peptone- and FCS-elicited cells, and high on thioglycollate-elicited cells. Transferrin transports iron into cells via the transferrin receptor: thus, iron content of resident cells is low, of peptone- and FCS-elicited cells is intermediate, and of thioglycollate-elicited cells is high. Moreover, antibody to transferrin, which prevents it binding its receptor, inhibits listericidal macrophages from killing this bacterium. Finally, nonlistericidal cells with high transferrin receptor expression and high intracellular iron become listericidal if they are incubated with apotransferrin, an iron-free ligand which prevents iron uptake by cells. These data suggest that macrophages must have enough available intracellular iron to support listericidal mechanisms, but too much iron favors growth of the bacterium, which no longer can be killed by the macrophage.

Diltiazem inhibits transferrin receptor expression and causes G1 arrest in normal and neoplastic T cells

1986 ◽  
Vol 6 (12) ◽  
pp. 4244-4250
Author(s):  
L M Neckers ◽  
S Bauer ◽  
R C McGlennen ◽  
J B Trepel ◽  
K Rao ◽  
...  
Keyword(s):  
T Cells ◽  
Transferrin Receptor ◽  
Interleukin 2 ◽  
Receptor Expression ◽  
Calcium Flux ◽  
G1 Arrest ◽  
Receptor Mrna ◽  
Interleukin 2 Receptor ◽  
Transferrin Receptor Expression ◽  
Malignant T Cells

Transferrin receptor expression is essential for the proliferation of both normal and malignant T cells. While transferrin receptor expression in normal T cells is tightly coupled to interleukin-2 receptor expression, transferrin receptor expression in malignant cells is usually constitutive and is released from this constraint. Temporally, the appearance of these membrane receptors is preceded by changes in the expression of the proto-oncogenes c-myc and c-myb. In addition, although an increase in the level of intracellular free calcium occurs early in the sequence of T-cell activation, the activation events dependent on this calcium flux have not been resolved. In the present study we report that diltiazem, an ion channel-blocking agent that inhibits calcium influx, arrested the growth in vitro of both normal and malignant human T cells in the G1 phase of the cell cycle. However, diltiazem did not inhibit the expression of c-myc or interleukin-2 receptor mRNA and protein in normal mitogen-activated T cells or the constitutive expression of c-myc and c-myb mRNA in malignant T cells (T acute lymphoblastic leukemia cells). In contrast, diltiazem prevented the induction of transferrin receptor (mRNA and protein) in normal T cells and caused a progressive loss of transferrin receptor (mRNA and protein) in malignant T cells. These data demonstrate that diltiazem can dissociate several growth-related processes normally occurring in G1 and thereby disrupt the biochemical cascade leading to cell proliferation.

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