Molecular evidence for the role of a ferric reductase in iron transport

Duodenal cytochrome b (Dcytb) is a haem protein similar to the cytochrome b561 protein family. Dcytb is highly expressed in duodenal brush-border membrane and is implicated in dietary iron absorption by reducing dietary ferric iron to the ferrous form for transport via Nramp2/DCT1 (divalent-cation transporter 1)/DMT1 (divalent metal-transporter 1). The protein is expressed in other tissues and may account for ferric reductase activity at other sites in the body.

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The molecular basis of copper and iron interactions

Proceedings of The Nutrition Society ◽

10.1079/pns2004386 ◽

2004 ◽

Vol 63 (4) ◽

pp. 563-569 ◽

Cited By ~ 79

Author(s):

Paul Sharp

Keyword(s):

Apical Membrane ◽

Dietary Supplementation ◽

Intimate Relationship ◽

Divalent Metal ◽

Efflux Transporter ◽

Transport Pathway ◽

Divalent Metal Transporter 1 ◽

Divalent Metal Transporter ◽

Metal Transporter

The intimate relationship between Fe and Cu in human nutrition has been recognised for many years. The best-characterised link is provided by caeruloplasmin, a multiCu-binding protein that acts as a serum ferrioxidase and is essential for the mobilisation of Fe from storage tissues. Decreased Cu status has been shown to reduce holo-caeruloplasmin production and impair ferrioxidase activity, leading, in a number of cases, to decreased tissue Fe release and the generation of anaemia that is responsive to dietary supplementation with Cu but not Fe. Dietary Fe absorption also requires the presence of a multiCu ferrioxidase. Hephaestin, a caeruloplasmin homologue, works in concert with the IREG1 transporter to permit Fe efflux from enterocytes for loading onto transferrin. The essential role of hephaestin in this process has been recognised from studies in the sex-linked anaemic (sla) mouse, in which Fe efflux is markedly impaired as a result of a mutation in the hephaestin gene that results in a truncated and non-functional version of the protein. There is emerging evidence that a number of other components of the intestinal Fe transport pathway are also Cu sensitive. Divalent metal transporter 1 (DMT1), the Fe transporter located at the apical membrane of enterocytes, is also a physiologically-relevant Cu transporter, suggesting that these two metals may compete with each other for uptake into the duodenal enterocytes. Furthermore, expression of both DMT1 and the basolateral Fe-efflux transporter IREG1 can be regulated by Cu, suggesting that the Fe–Cu relationship may be more complex than first thought.

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Influence of DMT1 and iron status on inflammatory responses in the lung

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00343.2010 ◽

2011 ◽

Vol 300 (4) ◽

pp. L659-L665 ◽

Cited By ~ 22

Author(s):

Jonghan Kim ◽

Ramon M. Molina ◽

Thomas C. Donaghey ◽

Peter D. Buckett ◽

Joseph D. Brain ◽

...

Keyword(s):

Lung Injury ◽

Inflammatory Responses ◽

Iron Status ◽

Pulmonary Inflammation ◽

Intratracheal Instillation ◽

Cell Content ◽

Divalent Metal Transporter 1 ◽

Divalent Metal Transporter ◽

Metal Transporter

Divalent metal transporter 1 (DMT1) is the major iron transporter responsible for duodenal dietary iron absorption and is required for erythropoiesis. Recent studies suggest that loss of DMT1 activity could be involved in metal-related lung injury, but little is known about the effects of iron status and DMT1 function on pulmonary inflammation. To better define the role of DMT1 and iron status in pulmonary inflammatory responses, we performed bronchoalveolar lavage (BAL) following intratracheal instillation of lipopolysaccharide (LPS) to the Belgrade rat, an animal model deficient in DMT1 function. In the basal state, the BAL fluid of Belgrade rats had more macrophages and higher lactate dehydrogenase, myeloperoxidase, albumin, and hemoglobin levels compared with heterozygote control rats. Following LPS instillation, the macrophage fraction relative to total BAL cell content and levels of albumin and IgM were increased in Belgrade rats compared with controls. In contrast, heterozygote Belgrade rats made anemic by diet-induced iron deficiency exhibited attenuated inflammatory responses to LPS. These combined results show that pulmonary inflammation can be modified by both DMT1 and iron status. Loss of DMT1 alters pulmonary responses necessary for lung homeostasis in the basal state and enhances LPS-induced inflammation and therefore would contribute to progression of lung injury.

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Exploring the Role of Divalent Metal Transporter 1 in Morphine-Mediated Upregulation of Neuronal Ferritin Heavy Chain

10.17918/00000264 ◽

2020 ◽

Author(s):

Ipek Gozen Eralp

Keyword(s):

Heavy Chain ◽

Divalent Metal ◽

Divalent Metal Transporter 1 ◽

Divalent Metal Transporter ◽

Metal Transporter ◽

Ferritin Heavy Chain

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The role of Dcytb in iron metabolism: an update

Biochemical Society Transactions ◽

10.1042/bst0361239 ◽

2008 ◽

Vol 36 (6) ◽

pp. 1239-1241 ◽

Cited By ~ 57

Author(s):

Andrew T. McKie

Keyword(s):

Iron Absorption ◽

Reductase Activity ◽

Duodenal Mucosa ◽

Ferric Reductase ◽

Expression And Purification ◽

Madin Darby Canine Kidney ◽

Additional Increase ◽

Haem Protein ◽

Darby Canine Kidney

Dcytb (duodenal cytochrome b) is an iron-regulated ferric reductase highly expressed in duodenal enterocytes. Its location and strong regulation by iron has indicated it plays an important role in iron absorption. Expression of Dcytb in cells (Caco-2 and MDCK) was found to increase both ferric reductase activity and stimulate uptake of 59Fe. An additional increase in cupric reductase activity was found in MDCK (Madin–Darby canine kidney) cells expressing Dcytb. Expression and purification of Dcytb in insect cells reveals that Dcytb is a di-haem protein and that the haems are reducible by ascorbate, indicating that ascorbate is the likely intracelluar electron donor. Studies underway in Dcytb-knockout mice reveal that Dcytb is the only iron-regulated ferric reductase in the duodenal mucosa and that loss of Dcytb affects iron absorption.

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Role of the iron‐import protein DMT1 (Divalent Metal Transporter 1) in liver iron uptake

The FASEB Journal ◽

10.1096/fasebj.26.1_supplement.641.27 ◽

2012 ◽

Vol 26 (S1) ◽

Author(s):

Chia-Yu Wang ◽

Mitchell Knutson

Keyword(s):

Iron Uptake ◽

Divalent Metal ◽

Liver Iron ◽

Divalent Metal Transporter 1 ◽

Divalent Metal Transporter ◽

Metal Transporter

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Involvement of DMT1 in uptake of Cd in MDCK cells: role of protein kinase C

AJP Cell Physiology ◽

10.1152/ajpcell.2001.281.3.c793 ◽

2001 ◽

Vol 281 (3) ◽

pp. C793-C800 ◽

Cited By ~ 41

Author(s):

Luisa Olivi ◽

Jeanne Sisk ◽

Joseph Bressler

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Mdck Cells ◽

Biochemical Properties ◽

Divalent Metal Transporter 1 ◽

Hek 293 ◽

Divalent Metal Transporter ◽

Metal Transporter ◽

Kinase C

The involvement of iron (Fe) transporters in the uptake of cadmium (Cd) was examined in Madin-Darby kidney cells (MDCK). The uptake of Cd displayed properties that are associated with the Fe transporter divalent metal transporter 1 (DMT1). For example, the uptake of Cd and Fe was reduced by altering the cell membrane potential. The uptake of Cd was blocked by Fe, and the uptake of Fe was blocked by Cd. Also, the uptake of Cd and Fe was higher in MDCK cells bathed in a buffer at low pH. Increased uptake of Fe and Cd was observed in the HEK-293 cell line overexpressing DMT1. Overnight treatment of MDCK cells with the protein kinase C activator phorbol 12,13-dibutyrate (PDBu) resulted in increased uptake of Cd and Fe and an increase in DMT1 mRNA. An increase in newly transcribed DMT1 mRNA was not observed, suggesting that PDBu does not increase DMT1 mRNA by activating transcription. Rather, the increase was most likely due to greater stability of DMT1 mRNA, because the rate of degradation of DMT1 mRNA was slower in MDCK cells treated with PDBu. Our results suggest that Fe and Cd are transported in MDCK cells by a transporter with biochemical properties similar to those of DMT1.

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Iron absorption by Belgrade rat pups during lactation

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00153.2007 ◽

2007 ◽

Vol 293 (3) ◽

pp. G640-G644 ◽

Cited By ~ 15

Author(s):

Khristy Thompson ◽

Ramon M. Molina ◽

Thomas Donaghey ◽

Joseph D. Brain ◽

Marianne Wessling-Resnick

Keyword(s):

Iron Absorption ◽

Divalent Metal ◽

Nonheme Iron ◽

Divalent Metal Transporter 1 ◽

Divalent Metal Transporter ◽

Metal Transporter ◽

Rat Pups ◽

Iron Assimilation ◽

Kidney Liver

Divalent metal transporter-1 (DMT1) mediates dietary nonheme iron absorption. Belgrade ( b) rats have defective iron metabolism due to a mutation in the DMT1 gene. To examine the role of DMT1 in neonatal iron assimilation, b/b and b/+ pups were cross-fostered to F344 Fischer dams injected with59FeCl3twice weekly during lactation. Tissue distribution of the radioisotope in the pups was determined at weaning ( day 21). The b/b pups had blood59Fe levels significantly lower than b/+ controls but significantly higher59Fe tissue levels in heart, bone marrow, skeletal muscle, kidney, liver, spleen, stomach, and intestines. To study the pharmacokinetics of nonheme iron absorption at the time of weaning,59FeCl3was administered to 21-day-old b/b and b/+ rats by intragastric gavage. Blood59Fe levels measured 5 min to 4 h postgavage were significantly lower in b/b rats, consistent with impaired DMT1 function in intestinal iron absorption. Tissue59Fe levels were also lower in b/b rats postgavage. Combined, these data suggest that DMT1 function is not essential for iron assimilation from milk during early development in the rat.

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Divalent Metal Transporter 1 Knock-Down Modulates IL-1β Mediated Pancreatic Beta-Cell Pro-Apoptotic Signaling Pathways through the Autophagic Machinery

International Journal of Molecular Sciences ◽

10.3390/ijms22158013 ◽

2021 ◽

Vol 22 (15) ◽

pp. 8013

Author(s):

Taewook Kang ◽

Honggang Huang ◽

Thomas Mandrup-Poulsen ◽

Martin R. Larsen

Keyword(s):

Cell Death ◽

Divalent Metal ◽

Β Cells ◽

Β Cell ◽

Divalent Metal Transporter 1 ◽

Divalent Metal Transporter ◽

Knock Down ◽

Metal Transporter ◽

Cell Functions ◽

Protective Proteins

Pro-inflammatory cytokines promote cellular iron-import through enhanced divalent metal transporter-1 (DMT1) expression in pancreatic β-cells, consequently cell death. Inhibition of β-cell iron-import by DMT1 silencing protects against apoptosis in animal models of diabetes. However, how alterations of signaling networks contribute to the protective action of DMT1 knock-down is unknown. Here, we performed phosphoproteomics using our sequential enrichment strategy of mRNA, protein, and phosphopeptides, which enabled us to explore the concurrent molecular events in the same set of wildtype and DMT1-silenced β-cells during IL-1β exposure. Our findings reveal new phosphosites in the IL-1β-induced proteins that are clearly reverted by DMT1 silencing towards their steady-state levels. We validated the levels of five novel phosphosites of the potential protective proteins using parallel reaction monitoring. We also confirmed the inactivation of autophagic flux that may be relevant for cell survival induced by DMT1 silencing during IL-1β exposure. Additionally, the potential protective proteins induced by DMT1 silencing were related to insulin secretion that may lead to improving β-cell functions upon exposure to IL-1β. This global profiling has shed light on the signal transduction pathways driving the protection against inflammation-induced cell death in β-cells after DMT1 silencing.

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