Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Missense mutations in the ferroportin gene (SLC11A3) result in haemochromatosis type 4 [HFE4, Online Mendelian Inheritance in Man (OMIM) reference 606069] or ferroportin disease, an autosomal dominant disorder characterized by predominantly reticuloendothelial iron accumulation. To verify whether HFE4 is caused by defective iron recycling because of loss of functionality of ferroportin, we down-regulated SLC11A gene expression in human macrophages by using small interfering RNAs (siRNAs). Transfection experiments with ferroportin siRNAs resulted in a marked reduction (about two-thirds on average) in ferroportin mRNA levels as detected by quantitative real time polymerase chain reaction. When macrophages were grown in medium supplemented with iron, cells transfected with siRNAs displayed three- to eightfold increases in staining intensities following Perls reaction. These macrophages also showed significant increases in H-ferritin content. The observation that ferroportin mRNA down-regulation to levels compatible with haplo-insufficiency causes increased iron retention and H-ferritin synthesis in cultured macrophages has important implications. First, this indicates that ferroportin levels must be finely regulated in order to maintain cellular iron homeostasis, and that both copies of SLC11A3 must function efficiently to prevent iron accumulation. Second, this observation supports the hypothesis that reticuloendothelial iron overload in patients with ferroportin disease is caused by loss-of-function mutations in the SLC11A3 gene that mainly impair macrophage iron recycling.
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PMID:Ferroportin gene silencing induces iron retention and enhances ferritin synthesis in human macrophages. 1556 64

A large body of evidence indicates that the level of serum ferritin parallels the concentration of storage iron within the body, regardless of the cell type in which it is stored. Elevated serum ferritin levels, in the absence of inflammation and liver disease, are currently taken to indicate increased iron stores and require further investigation to determine the site of iron overload. Until recently, the only genetic disorder with elevated serum ferritin levels known in Western countries was hereditary HLA-related HFE-related genetic haemochromatosis in Caucasians (HFE, OMIM 235200), and a high serum ferritin in apparently healthy persons was considered suggestive of this disease. In the last few years, at least two novel genetic disorders of iron metabolism presenting as unexplained hyperferritinaemia have been recognized. The first one is hereditary hyperferritinaemia/cataract syndrome (HHCS, OMIM 600886). HHCS arises from various point mutations or deletions within a protein binding sequence in the 5'-UTR of the L-ferritin mRNA that results in increased efficiency of L-ferritin translation. The second one is haemochromatosis type 4, or HFE4 (OMIM 606069), or ferroportin disease. In this latter condition, reticuloendothelial iron overload and hyperferritinaemia are caused by loss-of-function mutations in the SLC11A3 gene that mainly impair macrophage iron recycling. These genetic disorders should be taken into account in the differential diagnosis of unexplained hyperferritinaemia.
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PMID:Role of ferritin and ferroportin genes in unexplained hyperferritinaemia. 1573 88

The cellular iron exporter ferroportin 1 is expressed in both the duodenum and in cells of the mononuclear phagocyte system. Expression of ferroportin 1 protein on the cell surface is regulated by the interaction of ferroportin 1 with hepcidin. Hepcidin treatment of cells results in internalization and lysosomal degradation of cell surface ferroportin 1. Recently, ferroportin 1 mutations leading to hemochromatosis (HFE4) have been identified. HFE4 differs from classical hemochromatosis in that there is a greater amount of macrophage iron sequestration. The data presented here demonstrate that HFE4 mutations are heterogeneous in their effects on protein function. Some mutations result in loss of function with partial protein sequestration in the ER. Others are indistinguishable from native ferroportin 1 and have a similar ability to deplete transfected cells of iron as evidenced by activation of the iron-response proteins and cellular ferritin depletion. Significantly, all mutants appear to be unresponsive to hepcidin and do not demonstrate the expected internalization on exposure to hepcidin. The clinical phenotypes observed in patients may be secondary to cell-type-specific defects in hepcidin-mediated inhibition of ferroportin 1 expression.
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PMID:Functional consequences of ferroportin 1 mutations. 1593 10