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Background: Brain iron accumulation is a feature of Alzheimer disease (AD) but whether a chronic dietary iron overload contributes to AD induction is unknown. We previously showed that young mice fed a high iron diet did not display cognitive impairment despite the AD pathological markers in hippocampus.Objectives: We aim to compare the impact of high dietary iron on brain pathologic changes and cognitive function in young and old mice.Methods: Male C57BL/6J mice at 1 mo and 13 mo of age were fed with either a control diet (66 mg Fe/kg; Young-Ctrl and Old-Ctrl) or a high iron diet (14 g Fe/kg; Young-High Fe and Old-High Fe) for 7 mo, and outcomes were evaluated at 8 mo and 20 mo of age. Iron concentrations in brain regions were measured by atomic absorption spectrophotometry. Perls's Prussian blue staining and amyloid-β (Aβ) immunostaining were performed. Protein expression in the cerebral cortex and hippocampus was determined by immunoblotting. Superoxide dismutase activity and malondialdehyde concentration were examined. Cognitive functions were tested with the Morris water maze system. Two-factor ANOVA was used to analyze most data.Results: Compared with Old-Ctrl mice, Old-High Fe mice showed significantly higher iron concentrations in cerebral cortex (60% higher), cerebellum (60% higher), and hippocampus (90% higher), paralleled by lower superoxide dismutase activity and greater malondialdehyde concentration in cerebral cortex and hippocampus and worse cognitive function. In contrast, these variables did not significantly differ between the 2 young groups. Nevertheless, ferritin, phospho-tau, and Aβ1-42 expression in hippocampus and ferritin and Aβ1-42 expression in cerebral cortex were induced by the high iron diet irrespective of the age of mice (40-200% greater).Conclusions: High dietary iron induced cognitive defects in old mice but not young mice, suggesting that elderly people should avoid consuming abnormally high concentrations of iron. [ABSTRACT FROM AUTHOR]

Background: Brain iron deposition is a feature of Alzheimer disease and may contribute to its development. However, the relative contribution of dietary iron remains unclear.Objectives: We investigated the impact of high dietary iron on brain pathological changes and cognitive function in adult wild-type (WT) mice and amyloid precursor protein/presenilin 1 (APP/PS1) double transgenic mice.Methods: Male WT mice and APP/PS1 mice aged 10 wk were fed either a control diet (66 mg Fe/kg) (WT-Ctrl and APP/PS1-Ctrl) or a high iron diet (14 g Fe/kg) (WT-High Fe and APP/PS1-High Fe) for 20 wk. Iron concentrations in brain regions were measured by atomic absorption spectrophotometry. Brain iron staining and amyloid-β (Aβ) immunostaining were performed. Protein expressions in the hippocampus were determined by immunoblotting. Superoxide dismutase (SOD) activity and malondialdehyde concentration were examined. Cognitive functions were tested with the Morris water maze system.Results: In the hippocampus, APP/PS1-High Fe mice had significantly higher iron concentration (2.5-fold) and ferritin (2.0-fold) than APP/PS1-Ctrl mice (P < 0.001), and WT-High Fe mice had significantly higher ferritin (2.0-fold) than WT-Ctrl mice (P < 0.001). Interestingly, APP/PS1 mice had significantly higher iron concentration (2-3-fold) and ferritin (2-2.5-fold) than WT mice fed either diet (P < 0.001). Histological analysis indicated that iron accumulated in the hippocampal dentate gyrus region in APP/PS1 mice, consistent with the pattern of Aβ deposition. For both mouse strains, iron treatment induced Aβ and phospho-τ expression (1.5-3-fold) in the hippocampus, but had little impact on oxidative stress and cognitive function. Furthermore, APP/PS1 mice had significantly lower SOD activity and higher malondialdehyde concentration than WT mice in the hippocampus (P < 0.0001), paralleled by apparent cognitive dysfunction.Conclusions: Dietary iron overload induces iron disorder and Aβ and phospho-τ expression in the hippocampus of adult WT and APP/PS1 transgenic mice. [ABSTRACT FROM AUTHOR]

Background: The accumulation of iron occurs in the central nervous system (CNS) in several neurodegenerative diseases. Although multi-copper ferroxidases (MCFs) play an important role in cellular iron metabolism and homeostasis, the mechanism of MCFs in the CNS remains unclear.Objective: The aim was to study the role of MCFs in CNS iron metabolism and homeostasis by using hephaestin/ceruloplasmin (Heph/Cp) double knockout (KO) mice.Methods: Heph/Cp double KO male mice were generated by crossing both single KO mice. In Heph/Cp KO and wild-type (WT) control mice at 4 wk and 6 mo of age, iron concentrations of selected brain regions were measured by atomic absorption spectrophotometry, and gene expressions of Heph, Cp, ferroportin 1 (Fpn1) [+ iron responsive element (IRE)], L-ferritin, H-ferritin, transferrin receptor 1 (Tfrc), and divalent metal transporter 1 (Dmt1) (+IRE) were quantitated by quantitative reverse transcriptase-polymerase chain reaction. Brain region L-ferritin protein concentration, superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities and malondialdehyde (MDA) concentration were also determined. Learning and memory abilities in Heph/Cp KO and WT control mice at 6 mo of age were tested by the IntelliCage system (New Behavior).Results: Iron concentration was significantly higher in Heph/Cp KO mice than in WT control mice at 4 wk of age in the cortex (50%), hippocampus (120%), brainstem (35%), and cerebellum (220%) and at 6 mo of age in the cortex (140%), hippocampus (420%), brainstem (560%), and cerebellum (340%). L-Ferritin and MDA concentrations were significantly higher and SOD and GPx activities were significantly lower in the cortex, hippocampus, brainstem, and cerebellum of KO mice than in those of WT controls at both 4 wk and 6 mo of age. Iron-related gene expressions also differed significantly between groups. Learning and memory deficits occurred in Heph/Cp KO mice at 6 mo of age.Conclusion: Mutation of both MCFs in mice induces iron accumulation in brain regions, oxidative damage, and learning and memory defects. [ABSTRACT FROM AUTHOR]

Ferritin iron from food is readily bioavailable to humans and has the potential for treating iron deficiency. Whether ferritin iron absorption is mechanistically different from iron absorption from small iron complexes/salts remains controversial. Here, we studied iron absorption (RBC (59)Fe) from radiolabeled ferritin iron (0.5 mg) in healthy women with or without non-ferritin iron competitors, ferrous sulfate, or hemoglobin. A 9-fold excess of non-ferritin iron competitor had no significant effect on ferritin iron absorption. Larger amounts of iron (50 mg and a 99-fold excess of either competitor) inhibited iron absorption. To measure transport rates of iron that was absorbed inside ferritin, rat intestinal segments ex vivo were perfused with radiolabeled ferritin and compared to perfusion with ferric nitrilotriacetic (Fe-NTA), a well-studied form of chelated iron. Intestinal transport of iron absorbed inside exogenous ferritin was 14.8% of the rate measured for iron absorbed from chelated iron. In the steady state, endogenous enterocyte ferritin contained >90% of the iron absorbed from Fe-NTA or ferritin. We found that ferritin is a slow release source of iron, readily available to humans or animals, based on RBC iron incorporation. Ferritin iron is absorbed by a different mechanism than iron salts/chelates or heme iron. Recognition of a second, nonheme iron absorption process, ferritin endocytosis, emphasizes the need for more mechanistic studies on ferritin iron absorption and highlights the potential of ferritin present in foods such as legumes to contribute to solutions for global iron deficiency. [ABSTRACT FROM AUTHOR]

We previously detected a membrane-bound, copper-containing oxidase that may be involved in iron efflux in BeWo cells, a human placental cell line. We have now identified a gene encoding a predicted multicopper ferroxidase (MCE) with a putative C-terminal membrane-spanning sequence and high sequence identity to hephaestin (Heph) and ceruloplasmin (Cp), the other known vertebrate MCF. Molecular modeling revealed conservation of all type I, II, and Ill copper-binding sites as well as a putative iron-binding site. Protein expression was observed in multiple diverse mouse tissues, including placenta and mammary gland, and the expression pattern was distinct from that of Cp and Heph. The protein possessed ferroxidase activity, and protein levels decreased in cellular copper deficiency. Knockdown with small interfering RNA in BeWo cells indicates that this gene represents the previously detected oxidase. We propose calling this new member of the MCF family "zyklopen." [ABSTRACT FROM AUTHOR]

Background: Iron accumulation in the central nervous system (CNS) is a common feature of many neurodegenerative diseases. Multicopper ferroxidases (MCFs) play an important role in cellular iron metabolism. However, the role of MCFs in the CNS in health and disease remains poorly characterized., Objective: The aim was to study the role of hephaestin (HEPH) and ceruloplasmin (CP) in CNS iron metabolism and homeostasis., Methods: Iron concentrations and L-ferritin protein levels of selected brain regions were determined in global hephaestin knockout (Heph KO), global ceruloplasmin knockout (Cp KO), and wild-type (WT) male mice at 6-7 mo of age. Gene expression of divalent metal transporter 1 (Dmt1), ferroportin 1 (Fpn1), Heph, Cp, and transferrin receptor 1 (Tfrc) and HEPH protein level was quantitated in the same brain regions., Results: Iron and L-ferritin protein levels were significantly increased in Heph KO mouse brain cortex (iron: 30%, P < 0.05; L-ferritin: 200%, P < 0.05), hippocampus (iron: 80%, P < 0.05; L-ferritin: 300%, P < 0.05), brainstem (iron: 20%, P < 0.05; L-ferritin: 150%, P < 0.05), and cerebellum (iron: 20%, P < 0.05; L-ferritin: 100%, P < 0.05) regions than in WT and Cp KO mouse brain regions at 6 mo of age. Expression of the Heph gene was significantly increased in the Cp KO mouse cortex (100%; P < 0.01), hippocampus (350%; P < 0.001), brainstem (30%; P < 0.01), and cerebellum (150%; P < 0.001) than in WT controls, and Cp gene expression was significantly decreased in the Heph KO mouse hippocampus (20%; P < 0.05) than in WT control mice at 6 mo of age., Conclusions: Ablation of HEPH or CP results in disordered brain iron homeostasis in mice. Heph KO may provide a novel model for neurodegenerative disorders., (© 2015 American Society for Nutrition.)

Copper and iron metabolism intersect in mammals. Copper deficiency simultaneously leads to decreased iron levels in some tissues and iron deficiency anemia, whereas it results in iron overload in other tissues such as the intestine and liver. The copper requirement of the multicopper ferroxidases hephaestin and ceruloplasmin likely explains this link between copper and iron homeostasis in mammals. We investigated the effect of in vivo and in vitro copper deficiency on hephaestin (Heph) expression and activity. C57BL/6J mice were separated into 2 groups on the day of parturition. One group was fed a copper-deficient diet and another was fed a control diet for 6 wk. Copper-deficient mice had significantly lower hephaestin and ceruloplasmin (approximately 50% of controls) ferroxidase activity. Liver hepcidin expression was significantly downregulated by copper deficiency (approximately 60% of controls), and enterocyte mRNA and protein levels of ferroportin1 were increased to 2.5 and 10 times, respectively, relative to controls, by copper deficiency, indicating a systemic iron deficiency in the copper-deficient mice. Interestingly, hephaestin protein levels were significantly decreased to approximately 40% of control, suggesting that decreased enterocyte copper content leads to decreased hephaestin synthesis and/or stability. We also examined the effect of copper deficiency on hephaestin in vitro in the HT29 cell line and found dramatically decreased hephaestin synthesis and activity. Both in vivo and in vitro studies indicate that copper is required for the proper processing and/or stability of hephaestin.