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Results for “IRON METABOLISM”

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At least 19 recordsLinked to original sources
PubMed1994

New advances in iron metabolism, iron deficiency, and iron overload.

Rapid advances were made in understanding the molecular and cellular bases of iron metabolism and its disorders. Molecular mechanisms for the cellular uptake, storage, and utilization of iron were clarified in investigations of the structure and functions of transferrin, transferrin receptor, ferritin, erythroid delta-aminolevulinic acid synthase, and the RNA-binding protein termed the iron responsive-element binding protein. Evidence was obtained that a nuclear DNA-binding protein, NF-E2, may be involved in the regulation of both hemoglobin synthesis in erythroid cells and of iron absorption in the intestine. Clinically, progress was made in improving the diagnosis and management of both iron deficiency and iron overload, with studies of the usefulness of serum transferrin receptor measurements, of a new therapeutic preparation of iron using a "gastric delivery system," and of the development of new orally active iron-chelating agents.

Anemia, Iron-Deficiency↗
PubMed2000

Iron metabolism: iron deficiency and iron overload.

Iron is an essential cofactor in a variety of cellular processes. Except for a few unusual bacterial species, iron is indispensable for living organisms. However, free iron is toxic because of its propensity to induce the formation of dangerous free radicals. Consequently, iron balance is tightly regulated. Disorders of iron homeostasis are among the most common afflictions of humans. This review discusses inherited iron deficiency and iron overload disorders and recent insights into their pathophysiology.

Anemia, Iron-Deficiency↗
PubMedDate not supplied

[Lipid metabolism, iron metabolic indices and the rates of aging in welders with occupational diseases of the respiratory organs].

A study was made of relationship between biologic age of welders and their health status. The results obtained suggest that evolution of occupational abnormalities of bronchipulmonary system may accelerate the welders' rate of aging two-fold. Accumulation of iron in the organism of welders furthers the process of ageing as well. A high specific weight of patients with critically low level of the blood serum content of cholesterol (3.34 mmol/l) was found to be the case among welders with occupational abnormalities of bronchipulmonary system, which fact suggests a high risk for the pulmonary cancer development.

Adult↗
PubMed2006

Mild copper deficiency alters gene expression of proteins involved in iron metabolism.

Iron and copper homeostasis share common proteins and are therefore closely linked to each other. For example, copper-containing proteins like ceruloplasmin and hephaestin oxidize Fe(2+) during cellular export processes for transport in the circulation bound to transferrin. Indeed, copper deficiency provokes iron metabolism disorders leading to anemia and liver iron accumulation. The aim of the present work was to understand the cross-talk between copper status and iron metabolism. For this purpose we have established dietary copper deficiency in C57BL6 male mice during twelve weeks. Hematological parameters, copper and iron status were evaluated. cDNA microarray studies were performed to investigate gene expression profiles of proteins involved in iron metabolism in the liver, duodenum and spleen. Our results showed that copper deficiency induces microcytic and hypochromic anemia as well as liver iron overload. Gene expression profiles, however, indicate that hepatic and intestinal mRNA expression neither compensates for hepatic iron overload nor the anemia observed in this mouse model. Instead, major modifications of gene expression occurred in the spleen. We observed increased mRNA levels of the transferrin receptors 1 and 2 and of several proteins involved in the heme biosynthesis pathway (ferrochelatase, UroD, UroS,...). These results suggest that copper-deficient mice respond to the deficiency induced anemia by an adaptation leading to an increase in erythrocyte synthesis.

Anemia, Iron-Deficiency↗
PubMed2003

Comparative effects of the addition of meat from beef, chicken, mullet and hake to a bean seed ragout on iron metabolism and iron status in growing rats.

AIMS: The objective was to study the comparative effects of the addition of meat from beef, chicken, mullet and hake to a bean seed ragout (BSR) on iron metabolism and iron status in growing rats. METHODS: The iron metabolism and the iron status were investigated through the exploration of the total iron in the blood and the reserve of iron stored in the liver, spleen, intestine, heart and tibia. RESULTS: Our findings showed that the iron concentration in total blood significantly increased only in the BSR + beef group by 23% (p < 0.006) as compared to the control group (BSR). However, it significantly decreased in the BSR + chicken group by 19.3% (p < 0.002). The reserve of iron stored in the liver significantly increased in the BSR + beef and the BSR + hake groups by 69.5% (p < 0.003) and 160% (p < 2.5.10(-7)) respectively, as compared to the control group. The effect of hake was more pronounced than beef. However, in the BSR + chicken and the BSR + mullet groups, the reserve of iron stored in the liver did not significantly differ from the control group. The reserve of iron stored in the spleen increased significantly in all groups. The increase has reached 370% in the BSR + hake group (p < 1.10(-7)). In the intestine, the reserve of iron was significantly enhanced only in the group fed BSR + beef by 120% (p < 0.01). In contrast, this reserve was lower in the rats fed BSR + mullet than in the other groups, a reduction of 64% (p < 1.10(-5)) as compared to the control group. In the heart, iron concentration significantly increased between 36.5 and 50%, as compared to the control group. The iron stored in the tibia significantly increased only in the beef and the hake groups by 88% (p < 0.05) and 57.4% (p < 0.02) respectively. CONCLUSIONS: Our findings demonstrated that beef, chicken, mullet and hake did not have the same effect on iron metabolism and iron status in growing rats fed BSR diets. The rats fed BSR + beef have a better iron status than those fed BSR + hake, BSR + chicken or BSR + mullet in descending order.

Animals↗
PubMed2004

Down-regulation of iron regulatory protein 1 activities and expression in superoxide dismutase 1 knock-out mice is not associated with alterations in iron metabolism.

Iron and oxygen (O2) are intimately associated in many well characterized patho-physiological processes. These include oxidation of the [4Fe-4S] cluster of mitochondrial aconitase and inactivation of this Krebs cycle enzyme by the superoxide anion (O2*-), a product of the one-electron of reduction O2. In contrast to the apparent toxicity of this reaction, the biological consequences of O2*- -mediated inactivation of the cytosolic counterpart of mitochondrial aconitase, commonly known as iron regulatory protein 1 (IRP1), are not clear. Apart from its ability to convert citrate to iso-citrate, IRP1 in its apo-form binds to iron-responsive elements in the untranslated regions of mRNAs coding for proteins involved in iron metabolism, to regulate their synthesis and thus control the cellular homeostasis of this metal. Here, we show that in superoxide dismutase 1 (SOD1) knock-out mice, lacking Cu,Zn-SOD, an enzyme that acts to reduce the concentration of O2*- mainly in cytosol, not only is aconitase activity of IRP1 inhibited but the level of IRP1 is also strongly decreased. Despite such an evident alteration in IRP1 status, SOD1-deficient mice display a normal iron metabolism phenotype. Our findings clearly show that under conditions of O2*- -mediated oxidative stress, IRP1 is not essential for the maintenance of iron metabolism in mammals.

Aconitate Hydratase↗
PubMed2005

[Human iron metabolism].

Iron, associated with proteins and enzymes, mainly as heminic groups and Fe/S clusters, is essential for oxygen transport and many other biological functions. Systemic iron homeostasis is essentially a closed system. There is no regulated mechanism of iron excretion, for example through the liver or kidneys: iron losses occur only through bleeding and by shedding of mucosal and skin cells. These losses are compensated for by intestinal absorption. In contrast, iron absorption is tightly regulated. Three recently identified proteins, named HFE, hepcidin and hemojuvelin, play an important role in this regulation. About 20 other proteins have been shown to play a part in iron metabolism, often through studies of genetic diseases in humans or other animals. Mitochondria play a major role in iron metabolism.

Homeostasis↗
PubMedDate not supplied

Post-transcriptional regulation of human iron metabolism by iron regulatory proteins.

In mammalian iron metabolism, ferritin, transferrin receptor and several other iron metabolism genes are post-transcriptionally regulated. Iron regulatory proteins 1 and 2 are cytosolic proteins that bind to RNA stem-loops known as iron-responsive elements in several transcripts. We have studied the role of these proteins in knockout mice and discovered that misregulation of iron metabolism can be a primary cause of neurodegeneration.

Animals↗
PubMed2005

The emerging role of the liver in iron metabolism.

Iron is essential in health and well-being and its dysregulation is a common theme in disease. Recent advances in our understanding of the molecular biology underlying hemochromatosis and anemia has provided insight into the complex mechanisms implicated in iron metabolism. The proximal small bowel is the major site of iron absorption and, it is becoming increasingly clear that the regulation of this process involves the liver and, in particular, the hepatic antimicrobial peptide hepcidin. A number of studies have shown hepcidin to have an inhibitory function at the level of small bowel iron absorption, although its exact site of action remains to be elucidated. Clearly, identifying the target of hepcidin is of importance and is likely to lead to the development of therapeutic agents in the treatment of iron disorders.

Antigens, CD↗
PubMed1999

[Current data on iron metabolism].

Iron is required for cellular life. However, abnormalities of its metabolism may lead to iron deficiency or iron overload, both conditions which are deleterious. Therefore, stock and distribution of iron in the body must be very stable. Classically, four major proteins are involved in iron metabolism: (a) transferrin which is implicated in its plasmatic transport, (b) transferrin receptor which regulates iron-transferrin uptake, (c) ferritin, the major iron storage protein, and (d) IRP (Iron Regulatory Protein) which regulates both the entry and storage of iron by linking to the IRE (Iron Responsive Element), a nucleotidic sequence found on transferrin receptor and ferritin mRNA. Thus, IRP adapts gene expression to the iron cellular status. Recent data give informations about new proteins involved in iron metabolism: HFE whose gene is mutated in genetic hemochromatosis, ceruloplasmin which permits cellular iron egress and frataxin which is implicated in the exit of iron from mitochondria.

Animals↗
PubMed2003

Role of nitric oxide in cellular iron metabolism.

Iron regulatory proteins (IRP1 and IRP2) control the synthesis of transferrin receptors (TfR) and ferritin by binding to iron-responsive elements (IREs) which are located in the 3' untranslated region (UTR) and the 5' UTR of their respective mRNAs. Cellular iron levels affect binding of IRPs to IREs and consequently expression of TfR and ferritin. Moreover, NO*, a redox species of nitric oxide that interacts primarily with iron, can activate IRP1 RNA-binding activity resulting in an increase in TfR mRNA levels. We have shown that treatment of RAW 264.7 cells (a murine macrophage cell line) with NO+ (nitrosonium ion, which causes S-nitrosylation of thiol groups) resulted in a rapid decrease in RNA-binding of IRP2, followed by IRP2 degradation, and these changes were associated with a decrease in TfR mRNA levels. Moreover, we demonstrated that stimulation of RAW 264.7 cells with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) increased IRP1 binding activity, whereas RNA-binding of IRP2 decreased and was followed by a degradation of this protein. Furthermore, the decrease of IRP2 binding/protein levels was associated with a decrease in TfR mRNA levels in LPS/IFN-gamma-treated cells, and these changes were prevented by inhibitors of inducible nitric oxide synthase. These results suggest that NO+-mediated degradation of IRP2 plays a major role in iron metabolism during inflammation.

Animals↗
PubMed1989

The transferrin receptor: a key function in iron metabolism.

Iron is essential to cell proliferation. Its uptake by cells requires specific binding of the major serum iron-transport protein, transferrin, to cell surface transferrin receptors, followed by endocytosis of the receptor-ligand complexes and release of iron from endosomal vesicles to the cytoplasm. The structural and functional aspects of this pathway are reviewed. Intracellular iron either serves as a substrate for the biosynthesis of haem and iron-containing proteins or is stored in ferritin deposits. Recent studies are presented which establish that iron plays an important role in the maintenance of its own homeostasis by regulating coordinately the expression of both the transferrin receptor and ferritin. The elucidation of these regulatory mechanisms may become important to the understanding of certain disorders in iron-metabolism.

Cell Division↗
PubMed2000

[Iron metabolism].

Iron is essential to the human organism but is also highly toxic. Therefore, in the organism, iron is always tightly bound to specific proteins. In the past few years, our understanding of iron cellular uptake and regulation mechanisms has been expanded. However, iron metabolism, particularly its intestinal absorption and release from ferritin, is still uncompletely understood. Intestinal absorption appears to be the prime factor of iron homeostasis control. Iron deficiency is one of the most common nutritional problems in the world. However, oxidative stress induced by iron overload has been implicated in a growing number of diseases.

Cells↗
PubMed1995

Linkage of cell-mediated immunity to iron metabolism.

Iron is essential for growing microorganisms and tumour cells, and is also crucial for the proliferation of immune cells. In this review, Günter Weiss, Helmut Wachter and Dietmar Fuchs focus on the complex network of interactions that link iron metabolism with cellular immune effector functions involving cytokines and nitric oxide, and draw a suitable model for the pathogenesis of anaemia of chronic disease.

Animals↗