Role of ceruloplasmin and ascorbate in cellular iron release☆,☆☆,★
Section snippets
Materials
59Fe (as ferric chloride in 0.1 mol/L HCl) was purchased from Dupont (NEN products, Boston, Mass). Eagle's modified minimum essential medium, RPMI medium, and HBSS were obtained from Gibco Laboratories Ltd (Grand Island, NY). Ascorbate, BPS, human Tf, 2,4-dinitrophenol, quinine, reserpine, rotenone, sodium azide, and verapamil were obtained from Sigma Chemical Co (St Louis, Mo). Human Cp holoprotein (A610/A280 >0.045; 95% pure) was purchased from Calbiochem (La Jolla, Calif), and its
The effect of Cp on Fe uptake from 59Fe-NTA or 59Fe-Tf
Mukhopadhyay et al13 have demonstrated that in HepG2 cells made Fe deficient by means of a 16-hour incubation with 1 mmol/L BPS, Cp (30 μg/mL) markedly increased 55Fe uptake from the synthetic chelator NTA (0.5 μmol/L) after a 15-minute incubation at 25°C. In our hands, when these experiments were repeated by using 59Fe-NTA (0.5 μmol/L), no stimulation of 59Fe uptake by Cp was observed at 25°C or 37°C in control cells or in cells depleted of Fe by using BPS (1 mmol/L; Fig 1, A ) or DFO (100
Discussion
In the present investigation we have examined the effect of Cp on Fe uptake from 59Fe-NTA and 59Fe-Tf and its effect on Fe release from HepG2 cells. Our experiments demonstrate that Cp does not have any effect on 59Fe uptake from Fe-NTA or diferric Tf by control cells or cells that have been depleted of Fe by using the Fe chelators BPS or DFO (Fig 1, A and B ). However, Cp at physiologically relevant concentrations (the normal range in healthy human adult plasma is 210-450 μg/mL)13 can increase
Acknowledgements
I thank Mr Grant Darnell for his excellent technical assistance.
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Ascorbate and ferritin interactions: Consequences for iron release in vitro and in vivo and implications for inflammation
2019, Free Radical Biology and MedicineCitation Excerpt :Thus, rather than stabilizing ferritin iron, ascorbate simply reduces and solubilizes the ferritin core iron and thereby allows it to become more rapidly labelled with 59Fe. The apparent reduction in 59Fe release from cells [152,153] can be ascribed to an ascorbate-dependent decrease in the specific activity of the cytosolic LIP, due to enhanced unlabelled Fe(II) release from ferritin stores diluting the label released to the LIP after uptake from 59Fe-Tf. It was later found that preincubating cells with ascorbate delayed transference of ferritin 59Fe iron into the lysosomal compartment.
Mitochondrial dysfunction in the neuro-degenerative and cardio-degenerative disease, Friedreich's ataxia
2018, Neurochemistry InternationalCitation Excerpt :The Fe(II) has been shown to be first oxidized to Fe(III) by the transmembrane, copper-dependent ferroxidase, hephaestin, after it is exported by FPN1 (Fig. 1) (Lawen and Lane, 2013; Chiang et al., 2016). However, it is difficult to reconcile the role of hephaestin, as the soluble blood proteins, transferrin (TF) and ceruloplasmin, are thought to also oxidize Fe(II) to Fe(III) to enhance iron efflux from cells (Richardson, 1999; Huang et al., 2011). In the plasma, Fe(III) binds to apo-TF to form the primary plasma iron transport protein, holo-TF, which contains two high-affinity sites for Fe(III) (Fig. 1) (Richardson, 1999; Huang et al., 2011; Morgan, 1981).
Redox cycling metals: Pedaling their roles in metabolism and their use in the development of novel therapeutics
2016, Biochimica et Biophysica Acta - Molecular Cell ResearchThe active role of vitamin C in mammalian iron metabolism: Much more than just enhanced iron absorption!
2014, Free Radical Biology and MedicineCitation Excerpt :Ascorbate may also be able to modulate FPN1 [206] and/or cellular iron efflux activity [206,211]. We have shown that Asc can decrease iron release from various cell types [120,211], although whether this iron efflux is FPN1-dependent is unclear. Considering this, it is notable that physiological Asc levels caused an increase in FPN1 expression in intestinal epithelial-like human Caco-2 cells, which was associated with an increase in IRP2 and HIF2α [206].
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Supported by grants from the National Health and Medical Research Council of Australia (grant 970360) and the Kathleen Cuningham Foundation for Breast Cancer Research. D.R.R. was a recipient of a Research Fellowship and Senior Research Fellowship from the Department of Medicine, University of Queensland.
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Reprint requests: Des R. Richardson, PhD, Department of Medicine, University of Queensland, Clinical Sciences Building Floor C, Royal Brisbane Hospital, Brisbane, Australia, 4029.
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0022-2143/99 $8.00 + 0 5/1/100865