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)

Expression of wild type HFE reduces the ferritin levels of cells in culture. In this report we demonstrate that the predominant hereditary hemochromatosis mutation, C282Y(2) HFE, does not reduce ferritin expression. However, the second mutation, H63D HFE, reduces ferritin expression to a level indistinguishable from cells expressing wild type HFE. Further, two HFE cytoplasmic domain mutations engineered to disrupt potential signal transduction, S335M and Y342C, were functionally indistinguishable from wild type HFE in this assay, as was soluble HFE. These results implicate a role for the interaction of HFE with the transferrin receptor in lowering cellular ferritin levels.
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PMID:Interactions of the ectodomain of HFE with the transferrin receptor are critical for iron homeostasis in cells. 1107 91

Screening for hereditary hemochromatosis (HHC) by means of transferrin saturation (TS) levels has been advocated and will identify many patients who are asymptomatic. The purposes of this study were (1) to determine HFE genotypes among asymptomatic HHC patients and correlate this profile with the degree of iron overload and (2) to evaluate the relationship between mobilized iron (mob Fe), age, serum ferritin (SF), and quantitative hepatic iron (QHI) in this population. One hundred twenty-three asymptomatic HHC patients were evaluated; all had quantitative phlebotomy to determine mob Fe and genotyping for C282Y and H63D mutations. Liver biopsies with QHI determinations were performed on 72 of the 123 patients. Of the entire group, 60% were homozygous for C282Y, and 13% were compound heterozygotes (C282Y/H63D). Among asymptomatic patients, the prevalence of homozygous C282Y is lower compared with previous studies that include clinically affected patients. Of those patients with more than 4 g mob Fe, 77% were homozygous C282Y. Asymptomatic patients with lower iron burdens frequently had genotypes other than homozygous C282Y. There was no correlation between age and mob Fe in these patients; however, there was a correlation between mob Fe and both SF (r = 0.68) and QHI (r = 0.75). In conclusion, asymptomatic patients with moderate iron overload had a different genotypic profile than was seen in advanced iron overload. The significance of identifying patients with modest degrees of iron loading, who may not be homozygous for C282Y, must be addressed if routine TS screening is to be implemented. (Blood. 2000;96:3707-3711)
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PMID:Asymptomatic hemochromatosis subjects: genotypic and phenotypic profiles. 1109 50

Hemochromatosis is one of the most frequent genetic diseases among the white populations, affecting one in three hundred persons. Its diagnosis has been radically transformed by the discovery of the HFE gene. In a given individual, the diagnosis can, from now on, be ascertained on the sole association of a plasma transferrin saturation (TS) over 45% and homozygosity for the C282Y mutation. Liver biopsy is only required to search for cirrhosis whenever there is hepatomegaly and/or serum ferritin >1000 ng/ml and/or elevated serum AST. Family screening is mandatory, primarily centered on the siblings. The treatment remains based on venesection therapy which improves many features of the disease (one of the most refractory, however, being the joint signs) and permits normal life expectancy provided the diagnosis is established prior to the development of cirrhosis or of insulin-dependent diabetes. In view of the prevalence, the non-invasive diagnosis, the spontaneous severity and the efficacy of a very simple therapy, hemochromatosis should benefit from population screening. This screening could be based, first, on the assessment of transferrin saturation, followed - when elevated - by the search for the C282Y mutation. The discovery of the HFE gene has also paved the road for the individualization of other types of iron overload syndromes which are not HFE-related.
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PMID:Clinical aspects of hemochromatosis. 1109 95

Background: Hereditary hemochromatosis (HH) is a common autosomal recessive disease caused by an iron overload. Two mutations (C282Y and H63D) on the responsible HFE gene have been described. HH heterozygotes may have a slight iron overload that does not cause clinical disease. Compound heterozygosity may be associated with higher iron stores than C282Y heterozygosity. We studied biochemical iron parameters in HH C282Y and compound heterozygotes without a clinically significant iron overload. Methods: Data on hemoglobin, hematocrit, mean corpuscular volume, serum ferritin, serum iron, transferrin, and transferrin saturation were obtained from 40 C282 wild type controls (irrespective of H63D genotype), 61 C282Y heterozygotes, and 18 compound (C282Y/H63D) heterozygotes without clinical iron overload disease. Results: Serum ferritin levels were significantly higher in female HH heterozygotes, particularly in compound heterozygotes, than in normal women. In male heterozygotes, no difference in serum ferritin was found. We found higher mean serum iron and transferrin saturation levels in male and female HH heterozygotes than in normal controls, the highest in the group of compound heterozygotes. Conclusions: Mean serum ferritin (only in women), serum iron, and transferrin saturation are highest in compound heterozygotes and lowest in controls. C282Y heterozygotes seem to be an intermediate group between compound heterozygotes and the normal population.
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PMID:Biochemical expression of heterozygous hereditary hemochromatosis. 1111 55

HFE, the protein that is mutated in hereditary haemochromatosis, binds to the transferrin receptor (TfR). Here we show that wild-type HFE and TfR localize in endosomes and at the basolateral membrane of a polarized duodenal epithelial cell line, whereas the primary haemochromatosis HFE mutant, and another mutant with impaired TfR-binding ability accumulate in the ER/Golgi and at the basolateral membrane, respectively. Levels of the iron-storage protein ferritin are greatly reduced and those of TfR are slightly increased in cells expressing wild-type HFE, but not in cells expressing either mutant. Addition of an endosomal-targeting sequence derived from the human low-density lipoprotein receptor (LDLR) to the TfR-binding-impaired mutant restores its endosomal localization but not ferritin reduction or TfR elevation. Thus, binding to TfR is required for transport of HFE to endosomes and regulation of intracellular iron homeostasis, but not for basolateral surface expression of HFE.
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PMID:Binding to the transferrin receptor is required for endocytosis of HFE and regulation of iron homeostasis. 1527 68

Iron overload has been proposed as a cause of liver dysfunction after BMT Factors which could be relevant to iron overload include the number of red cell transfusions and mutations within the haemochromatosis gene (HFE). Two point mutations, Cys282Tyr and His63Asp, have been described within HFE. Cys282Tyr homozygosity is associated with haemochromatosis; the effect of compound heterozygosity, Cys282Tyr/His63Asp, on iron status is variable. We analysed HFE status in 52 allograft patients surviving more than 6 months. Compound heterozygosity was identified in three patients (Cases 1-3). Iron status and liver function were evaluated and, in Cases 1 and 2, liver histology and iron content as well. Case 3 who received 12 units of red cells had a normal ferritin and liver function. Cases 1 and 2 received 29 and 59 units, respectively, and had high serum ferritins and transferrin saturations, abnormal liver function and significant hepatic iron overload on biopsy. Iron overload in Case 1 patient progressed in the context of GVHD and in the absence of further transfusion, suggesting that liver GVHD may increase hepatic iron accumulation. These cases demonstrate the variable phenotypic expression of HFE compound heterozygosity in BMT recipients, which may be only partly explained by transfusional iron loading. Venesection or chelation therapy should be considered in patients with coexistent hepatic GVHD and iron overload.
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PMID:Compound heterozygosity for haemochromatosis gene mutations and hepatic iron overload in allogeneic bone marrow transplant recipients. 1128 Jun 7

Restless legs syndrome (RLS) occurs in some persons with iron deficiency, and some persons with RLS benefit from oral iron therapy. Approximately one in 200 persons of northern European ancestry have hemochromatosis attributable to inheritance of two common mutations of the hemochromatosis-associated HFE gene on chromosome 6. We evaluated and treated a 46-year-old man with RLS who was diagnosed as having hemochromatosis after he developed new symptoms associated with taking iron therapy for RLS. He had transferrin saturation 88%, serum ferritin 658 ng/ml, and C282Y homozygosity. Therapeutic phlebotomy of one unit of blood (450-500 ml) weekly (total 24 units) relieved his non-RLS symptoms, caused RLS symptoms to occur more frequently, and was associated with transient fatigue and mild dependent edema. His sister, who also has RLS, was subsequently diagnosed as having hemochromatosis. We conclude that serum transferrin saturation and ferritin levels should be measured before initiation of iron therapy of RLS. Patients with a history of iron deficiency or low serum iron parameters should undergo evaluation for iron deficiency; patients who have histories suggestive of hemochromatosis or iron overload or elevated pre-treatment transferrin saturation or serum ferritin levels should undergo evaluation to determine the cause of these abnormalities before they are treated with iron. In all persons with RLS treated with oral iron, serum iron parameters should be re-measured once or twice yearly during therapy.
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PMID:Hemochromatosis and iron therapy of Restless Legs Syndrome. 1131 89

The gene for hemochromatosis (HFE) is expressed in a variety of cells, including those not thought to be affected by this disease. The impact of HFE on iron transport was examined in B-lymphoid cell lines developed from a patient with hemochromatosis with the HFE C282Y mutation (C282Y cells) and an individual with the wild-type HFE gene (WT cells). Whereas both cell lines expressed HFE protein, C282Y cells displayed less HFE protein at the cell surface. Transferrin receptor (TfR) number was 2- to 3-fold greater in WT cells than in C282Y cells, while TfR affinity for transferrin (Tf) was slightly lower in C282Y cells. TfR distribution between intracellular and cell-surface compartments was similar in both cell lines. Iron uptake per cell was greater in WT cells but was not increased proportional to TfR number. When considered relative to cell-surface TfR number, however, iron uptake and Tf internalization were actually greater in C282Y cells. Surprisingly, Tf-independent iron uptake was also significantly greater in C282Y cells than in WT cells. The ferritin content of C282Y cells was approximately 40% that of WT cells. Exposure of cells to pro-oxidant conditions in culture led to a greater inhibition of proliferation in C282Y cells than in WT cells. Our results indicate that in this B-lymphoid cell line, the HFE C282Y mutation affects both Tf-dependent and -independent iron uptake and enhances cell sensitivity to oxidative stress. The role of HFE in iron uptake by B cells may extend beyond its known interaction with the TfR.
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PMID:Iron transport in a lymphoid cell line with the hemochromatosis C282Y mutation. 1131 65

In order to measure the effects of HFE (haemochromatosis) upon iron uptake, stable expression of wild-type and C282Y, H63D and S65C mutant HFE cDNA was established in HEK 293 cells. Control cells were transfected with empty vector. Expression of HFE mRNA and protein was detected in the cell lines transfected with HFE cDNA, but not in the control cell line. The ferritin concentration in wild-type cells cultured in 40 microM ferric ammonium citrate was 69% of that in control cells and 81% of that in C282Y cells. The ferritin concentration in H63D cells was intermediate between wild-type and C282Y and the ferritin concentration in S65C cells was similar to wild-type cells. Uptake of transferrin-iron in wild-type, C282Y and control cells was measured over 45 min. The Hill coefficients for transferrin-iron uptake were similar. The V(max) for transferrin-iron uptake in wild-type cells was 59.5% of control cells and 69.5% of C282Y cells. Estimates of K(m) were 232 nM for wild-type cells, 338 nM for C282Y cells and 570 nM for controls. Transferrin receptor levels were lowered, but not significantly, in the HFE transfected cells. The results show that HFE reduces transferrin-iron uptake, probably as an uncompetitive inhibitor.
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PMID:The effects of wild-type and mutant HFE expression upon cellular iron uptake in transfected human embryonic kidney cells. 1133 95

Three mutations in the transferrin receptor-2 gene have recently been identified in four Sicilian families with iron overload who had a normal hemochromatosis gene, HFE (C. Camaschella, personal communication). To determine the extent to which mutations in the transferrin receptor-2 gene occur in other populations with iron overload, we have completely sequenced this gene in 17 whites, 10 Asians, and 8 African Americans with iron overload and a C282C/C282C HFE genotype, as well as 4 subjects without iron overload and homozygous for the mutant HFE C282Y genotype, 5 patients with iron overload and homozygous for the mutant HFE C282Y genotype, and 5 normal individuals. None of the individuals exhibited the Sicilian mutations, Y250X in exon 6, M172K in exon 4, and E60X in exon 2. One iron-overloaded individual of Asian descent exhibited a I238M mutation which was subsequently found to be a polymorphism present in the Asian population at a frequency of 0.0192. The presence of the I238M mutation was not associated with an increase in ferritin or transferrin saturation levels. Three silent polymorphisms were also identified, nt 1770 (D590D) and nt 1851 (A617A) and a polymorphism at nt 2255 in the 3' UTR. Thus, mutations in the transferrin receptor-2 gene were not responsible for the iron overload seen in our subjects.
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PMID:Mutation analysis of the transferrin receptor-2 gene in patients with iron overload. 1135 91


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