The Hereditary Hemochromatosis Protein, HFE, Specifically Regulates Transferrin-mediated Iron Uptake in HeLa Cells

Roy, Cindy N.; Penny, David M.; Feder, John N.; Enns, Caroline A.

doi:10.1074/jbc.274.13.9022

Cited by 192 publications

(175 citation statements)

References 41 publications

Supporting

Mentioning

158

Contrasting

Unclassified

Order By: Relevance

“…By contrast, when wtTfR is incubated with a saturating amount of HFE, we observe a reduction in the apparent binding affinity for Fe-Tf, as previously reported (23). The experiments using hdTfR demonstrate that there is no cooperativity, either negative or positive, in heterotropic ligand binding by hdTfR, suggesting that the apparent lowering of the Fe-Tf affinity of cell surface and soluble wtTfR by HFE (8,23,39,40) results entirely from competition between HFE and Fe-Tf for overlapping binding sites on the TfR surface. Extending these results to wtTfR requires the assumption that the mutations used to create the hdTfR do not themselves disrupt cooperativity.…”

Section: Discussionmentioning

confidence: 48%

“…TfR can form binary complexes with either HFE or Fe-Tf and can bind both ligands simultaneously to form a 1:1:1 HFE⅐TfR⅐Fe-Tf ternary complex (18 -20). Characterizing the ternary complex is of interest, because both soluble and membrane-bound HFE reduce the apparent affinity of soluble and membrane-bound TfR for Fe-Tf (8,21,23,39). Since mixtures of binary and ternary complexes form when all three proteins are present (Fig.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

HFE and Transferrin Directly Compete for Transferrin Receptor in Solution and at the Cell Surface

Giannetti¹,

Björkman

2004

Journal of Biological Chemistry

129

View full text Add to dashboard Cite

Transferrin receptor (TfR) is a dimeric cell surface protein that binds both the serum iron transport protein transferrin (Fe-Tf) and HFE, the protein mutated in patients with the iron overload disorder hereditary hemochromatosis. HFE and Fe-Tf can bind simultaneously to TfR to form a ternary complex, but HFE binding to TfR lowers the apparent affinity of the Fe-Tf/TfR interaction. This apparent affinity reduction could result from direct competition between HFE and Fe-Tf for their overlapping binding sites on each TfR polypeptide chain, from negative cooperativity, or from a combination of both. To explore the mechanism of the affinity reduction, we constructed a heterodimeric TfR that contains mutations such that one TfR chain binds only HFE and the other binds only Fe-Tf. Binding studies using a heterodimeric form of soluble TfR demonstrate that TfR does not exhibit cooperativity in heterotropic ligand binding, suggesting that some or all of the effects of HFE on iron homeostasis result from competition with Fe-Tf for TfR binding. Experiments using transfected cell lines demonstrate a physiological role for this competition in altering HFE trafficking patterns.

show abstract

Section: Discussionmentioning

confidence: 48%

Section: Discussionmentioning

confidence: 99%

HFE and Transferrin Directly Compete for Transferrin Receptor in Solution and at the Cell Surface

Giannetti¹,

Björkman

2004

Journal of Biological Chemistry

129

View full text Add to dashboard Cite

show abstract

“…The high-affinity binding of HFE with TfR1 suggested that HFE-TfR1 complex formation might be important for the function of HFE protein in iron homeostasis (18)(19)(20)(21)(22)(23)(24)(25)(26). This hypothesis was supported by the observation that the transport of HFE to endosomes and the regulation of intracellular iron absorption in some cell lines depend on its association with TfR1 (27).Several studies on the interaction of HFE with TfR1 in transfected cell lines have attempted to characterize the biological effect of this interaction on iron homeostasis (22,23,(27)(28)(29)(30)(31). Several groups have reported that HeLa cells overexpressing HFE protein showed a decrease in ferritin level, an increase in TfR1, and an increase in iron regulatory protein activity, indicating lower levels of iron stores in the cells (22,23,30).…”

mentioning

confidence: 59%

Regulation of transferrin-mediated iron uptake by HFE, the protein defective in hereditary hemochromatosis

Waheed

Grubb

Zhou

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

124

View full text Add to dashboard Cite

The protein defective in hereditary hemochromatosis, called HFE, is similar to MHC class I-type proteins and associates with ␤2-microglobulin (␤2M). Its association with ␤2M was previously shown to be necessary for its stability, normal intracellular processing, and cell surface expression in transfected COS cells. Here we use stably transfected Chinese hamster ovary cell lines expressing both HFE and ␤ 2 M or HFE alone to study the effects of ␤ 2 M on the stability and maturation of the HFE protein and on the role of HFE in transferrin receptor 1 (TfR1)-mediated iron uptake. In agreement with prior studies on other cell lines, we found that overexpression of HFE, without overexpressing ␤2M, resulted in a decrease in TfR1-dependent iron uptake and in lower iron levels in the cells, as evidenced by ferritin and TfR1 levels measured at steady state. However, overexpression of both HFE and ␤2M had the reverse effect and resulted in an increase in TfR1-dependent iron uptake and increased iron levels in the cells. The HFE-␤2M complex did not affect the affinity of TfR1 for transferrin or the internalization rate of transferrin-bound TfR1. Instead, HFE-␤2M enhanced the rate of recycling of TfR1 and resulted in an increase in the steady-state level of TfR1 at the cell surface of stably transfected cells. We propose that Chinese hamster ovary cells provide a model to explain the effect of the HFE-␤2M complex in duodenal crypt cells, where the HFE-␤2M complex appears to facilitate the uptake of transferrin-bound iron to sense the level of body iron stores. Impairment of this process in duodenal crypt cells leads them to be iron poor and to signal the differentiating enterocytes to take up iron excessively after they mature into villus cells in the duodenum of hereditary hemochromatosis patients.H ereditary hemochromatosis (HH) is an autosomal recessive disorder of iron metabolism, characterized by excessive absorption of dietary iron in the small intestine. The excess iron is stored in the parenchymal cells of major tissues, primarily the liver, pancreas, heart, pituitary, and joints, eventually leading to severe tissue damage (1-3). The pathogenesis of HH is thought to involve a defect in the mechanism controlling iron absorption in the small intestine (4).The gene defective in hemochromatosis, HFE, encodes an MHC class I-type protein (5). In multiple population studies, 85-90% of HH patients of northern European ancestry were found to be homozygous for the C282Y mutation in HFE. About 5% are compound heterozygotes for C282Y and a second mutation, H63D (5-10). Even earlier, the observation that ␤ 2 -microglobulin (␤ 2 M)-deficient mice develop progressive iron overload similar to that seen in HH patients suggested the involvement of an MHC class I protein in HH (11, 12). Confirmation that mutations in HFE cause HH was provided by observations of mice with targeted disruption of the HFE gene. These HFE knockout mice showed high transferrin saturation and an increase in iron storage in hepatocytes (13-15).The C282Y mutati...

show abstract

“…The transferrin receptor is then recycled to the plasma membrane, where apotransferrin is released from the receptor (9,10). The efficiency of Fe acquisition from transferrin is influenced by the association of other proteins, HFE and ␤ 2 -microglobulin, with the transferrin receptor (13)(14)(15). The absence of functional HFE appears to play a critical role in hereditary hemochromatosis (16).…”

mentioning

confidence: 99%

Multivalent Metal-Induced Iron Acquisition from Transferrin and Lactoferrin by Myeloid Cells

Olakanmi

Rasmussen

Lewis

et al. 2002

The Journal of Immunology

View full text Add to dashboard Cite

We previously described a unique, high-capacity, ATP-independent mechanism through which myeloid cells acquire Fe from low-m.w. chelates. The rate of this Fe acquisition is markedly increased by cellular exposure to multivalent metal cations. Because most Fe in vivo is bound to transferrin or lactoferrin, we examined whether this mechanism also contributes to myeloid cell acquisition of Fe from transferrin and/or lactoferrin. Using HL-60 cells as a model system, we show cellular acquisition of 59Fe from both lactoferrin and transferrin that was unaffected by conditions that depleted the cells of ATP or disrupted their cytoskeleton. Fe acquisition was dramatically increased by cell exposure to various metals including Ga3+, Gd3+, Al3+, Fe3+, La3+, Zr4+, Sn4+, Cu2+, and Zn2+ by a process that was reversible. Exposure to these same metals also increased binding of both transferrin and lactoferrin to the cell surface by a process that does not appear to involve the well-described plasma membrane receptor for transferrin. Approximately 60% of the Fe acquired by the cells from transferrin and lactoferrin remained cell associated 18 h later. HL-60 cells possess a high-capacity multivalent metal-inducible mechanism for Fe acquisition from transferrin and lactoferrin that bears many similarities to the process previously described that allows these and other cell types to acquire Fe from low-m.w. Fe chelates. The biologic importance of this mechanism may relate to its high Fe acquisition capacity and the speed with which it is able to rapidly adapt to the level of extracellular Fe.

show abstract

The Hereditary Hemochromatosis Protein, HFE, Specifically Regulates Transferrin-mediated Iron Uptake in HeLa Cells

Cited by 192 publications

References 41 publications

HFE and Transferrin Directly Compete for Transferrin Receptor in Solution and at the Cell Surface

HFE and Transferrin Directly Compete for Transferrin Receptor in Solution and at the Cell Surface

Regulation of transferrin-mediated iron uptake by HFE, the protein defective in hereditary hemochromatosis

Multivalent Metal-Induced Iron Acquisition from Transferrin and Lactoferrin by Myeloid Cells

Contact Info

Product

Resources

About