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)

Hepatocellular carcinoma cells of the PLC/PRF/5 cell line had 1.9 x 10(5) transferrin receptors per tumor cell with a Kd of 1.5 x 10(-8) M. At high concentrations of transferrin the binding was not saturable. Transferrin internalization by hepatoma cells was shown by time and temperature-dependent binding studies and by pronase experiments. Transferrin recycling was confirmed by the demonstration of a progressive increase in the cellular molar ratios of iron to transferrin and by chase experiments. Ammonium chloride interfered with iron unloading. The vinca alkaloid vincristine inhibited iron and transferrin uptake. The hepatocarcinoma cells appeared to lack asialoglycoprotein receptors and therefore internalized partially desialated transferrin by the regular route. Iron uptake from transferrin was markedly inhibited by the hydrophobic ferrous chelator 2,2' bipyridine but was relatively unaffected by the hydrophilic ferric chelator desferroxamine. The implication that ferrous iron was involved in postendocytic transvesicular membrane iron transport was supported by a study in which hepatoma cells were shown to take up large amounts of ferrous iron suspended in 270 mM sucrose at pH 5.5. The interaction at this pH between surface labeled hepatoma cell extracts and ferrous iron on a Sephacryl S-300 column suggested that the postendocytic transvesicular transport of iron through the membrane was in part protein mediated. The endocytosed iron in hepatoma cells was found in association with ferritin (33%), transferrin (31%) and a low molecular weight fraction (21%).
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PMID:Transferrin iron interactions with cultured hepatocellular carcinoma cells (PLC/PRF/5). 316 34

The usefulness of the red cell distribution width, mean corpuscular volume, and the transferrin saturation in diagnosing iron deficiency anemia were evaluated in a retrospective study of 247 anemic hospitalized patients, many of whom had chronic liver disease. A red cell distribution width greater than 15% had a sensitivity of 71% and a specificity of 54% for iron deficiency as diagnosed by a low serum ferritin or bone marrow examination. A mean corpuscular volume less than 80 femtoliters had a sensitivity of 53% and a specificity of 84%. Transferrin saturation less than 16% had a sensitivity of 61% and a specificity of 86%. Because the sensitivities and specificities of these tests are less than reported in studies of healthier populations, they cannot be relied on for screening for iron deficiency in sick hospitalized patients.
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PMID:Red cell distribution width, mean corpuscular volume, and transferrin saturation in the diagnosis of iron deficiency. 317 71

Transferrin saturation was determined in 11,431 men and 10,639 women aged 15 or more drawn from different areas in southern and central Finland and attending a multiphasic health screening examination in 1967-1972. All the 163 men and 66 women with transferrin saturation greater than or equal to 70% at the initial examination and still alive at the end of 1983 were invited to a re-examination. Of the invited persons, 76% attended the re-examination. Transferrin saturation and serum ferritin were the initial screening methods in the re-examination. All persons with suspected hemochromatosis were clinically examined and a laparoscopy was performed. Four men and four women were found with unequivocal hemochromatosis. Only one of these cases was diagnosed beforehand. According to these data the prevalence of hemochromatosis in Finland is about 50/100,000.
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PMID:Prevalence of hemochromatosis in Finland. 318 89

A significant proportion of the world's population suffers from iron deficiency or iron overload. These disorders arise primarily from defects in the gastrointestinal absorption of iron. The intestinal mucosal cell plays a key role in this process because it lies at the interface between the gastrointestinal lumen which supplies its iron and body compartments which control its behaviour. The concentration of mucosal ferritin is closely linked to absorption, but it is still not clear whether it plays an active or a passive role. Transferrin also has been detected in the mucosal cell, but firm evidence that it participates in the absorptive process is lacking. Deficiencies in the luminal phase are responsible for the high global prevalence of iron deficiency which is predominantly dietary in origin. Much information has accumulated in recent years on dietary factors that enhance or impair iron absorption but their quantitative importance as determinants of iron status remains to be determined.
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PMID:Intestinal regulation of body iron. 333 11

Transferrin (Tf), a major secretory protein of Sertoli cells, may transport iron to spermatogenic cells. This was assessed by measuring the uptake of Fe from 59Fe-125I-labelled rat Tf by Sertoli cells and round spermatids in vitro. Uptake of Fe from labelled Tf by Sertoli cells after a 72-h pre-incubation period was linear for 20 h (approximately 18 pmol/10(6) cells/20 h), whereas the uptake of Fe from labelled Tf by round spermatids after a 16-h pre-incubation period reached a plateau by 2 h (approximately 5 pmol/10(6) cells/2 h). The corresponding net uptake of Tf by both cell types was less than 0.1 pmol. High speed supernatants prepared from Sertoli cells and spermatids labelled with 59Fe-125I-Tf were fractionated by gel permeation chromatography. Separate peaks of protein-bound 59Fe and 125I-Tf were observed. Protein bound 59Fe could be precipitated with an antiserum to rat ferritin. It is concluded that iron from exogenous Tf is transported into Sertoli cells and round spermatids in vitro, and is complexed to intracellular ferritin. However, the present results do not exclude the possibility that Sertoli cell Tf may serve purposes other than iron transport.
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PMID:Transport of transferrin-bound iron into rat Sertoli cells and spermatids. 342 53

We have studied the role of transferrin and the transferrin receptor in the uptake of 67Ga by the human leukemic cell line HL60. In the absence of transferrin, HL60 cells incorporated about 1% of the 67Ga dose over 6 h. The presence of transferrin increased cellular 67Ga uptake approximately 10-fold. Transferrin-mediated uptake of 67Ga was blocked by an anti-transferrin receptor monoclonal antibody, and decreases in the density of cellular transferrin receptors led to corresponding decreases in the transferrin-dependent uptake of 67Ga. Changes in the cellular ferritin content did not significantly influence the uptake of 67Ga by either transferrin-independent or transferrin-dependent pathways. Regardless of the mechanism of uptake, a significant amount of intracellular 67Ga was found to be associated with immunoprecipitable ferritin as well as with a free pool. This free intracellular 67Ga appeared to be kinetically active since cells released 67Ga back to the media over time. Our results demonstrate the existence of a dual mechanism for the cellular uptake of 67Ga and suggest that the preferential uptake of 67Ga by lymphomas is related to the high density of transferrin receptors known to be expressed by these tumors in vivo.
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PMID:Uptake of gallium-67 by human leukemic cells: demonstration of transferrin receptor-dependent and transferrin-independent mechanisms. 347 68

Transferrin receptors have been previously found on human macrophages and it has also been shown that transferrin iron is taken up by these cells. It has therefore been inferred that the uptake is receptor mediated and involves an endocytic pathway. The subject was addressed directly in the present study in which the transferrin-iron-receptor interaction was characterized in cultured human blood monocytes. Specific, saturable diferric transferrin binding was demonstrated, with a kDa of 3.6 X 10(-8) M and a calculated receptor density of 1.25-2.5 X 10(5) receptors per cell. Incubation at 4 degrees C markedly reduced transferrin binding and completely inhibited iron uptake. Chase experiments confirmed progressive cellular loading of iron, with concomitant loss of transferrin. Inhibitors of endocytic vesicle acidification (ammonium chloride and 2,4-dinitrophenol) inhibited iron unloading from endocytosed diferric transferrin, while microtubular inhibitors (colchicine and vindesine) and a microfilament inhibitor (cytochalasin B) reduced diferric transferrin uptake but had little effect on the iron unloading pathway. A similar effect was noted with a calcium ion antagonist (verapamil) and with 2 calmodulin antagonists (chlorpromazine and imipramine). These latter findings suggest the importance of cytoskeleton-membrane interactions via a calcium, calmodulin and protein kinase C mediated system. Endocytosed iron accumulated progressively as ferritin within the cultured monocytes.
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PMID:Transferrin receptors and transferrin iron uptake by cultured human blood monocytes. 362 25

The authors conducted a clinical investigation on sixty-nine pregnant women, anaemic and non-anaemic, the purpose being to assess the effect of 50 days treatment with four different medicinal iron preparations, namely, ferrous sulphate, iron chondroitinsulfuric acid complex, and ferritin alone or associated with folinic acid and cobamamide, on various haematological parameters (Hb, RCC, Ht, CV, Iron, and Transferrin IBC). The four products demonstrated a similar efficacy in maintaining anaemic conditions under control; moreover, the results confirmed our hypothesis of the absorption of iron ferritin. While three products were well tolerated, ferrous sulphate induced, in some cases, side-effects.
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PMID:Efficacy of iron therapy: a comparative evaluation of four iron preparations administered to anaemic pregnant women. 392 93

Transferrin receptors expressed by mitogen stimulated human lymphocytes mediate the uptake of transferrin iron into haem, ferritin and a non-haem, non-ferritin component. In spite of different rates of iron uptake by cells from different individuals, the proportional incorporation of 59Fe into these components was similar, suggesting that there was an obligatory relationship between the different forms of iron in the cells. By 3 h over 60% of the iron taken up was incorporated into ferritin while less than 10% was found in haem. Initially (10 min) non-haem, non-ferritin iron comprised 70% of total iron and this diminished to 30% by 3 h. At 10 min 80% of iron in the non-haem, non-ferritin component was retained by anti-transferrin affinity columns indicating it was transferrin-bound. The proportion retained fell to reach a steady state level of 50% by 60 min. These results indicate that 10-20% of the iron in the cells was not recognized as transferrin, ferritin or haem iron. The finding that iron incorporation into this unidentified pool reached equilibrium while that into haem and ferritin increased suggests the iron may act as a precursor for functional and storage compounds.
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PMID:Intracellular forms of iron during transferrin iron uptake by mitogen-stimulated human lymphocytes. 395 65

The rapidly growing human fetus requires a large supply of iron, which is obtained from the iron stores of the mother. Iron is transported from mother to fetus against a concentration gradient. The placenta plays a key role in regulating the supply of iron in the fetus. In both anemic and nonanemic patients serum ferritin levels decreased and total iron-binding capacity increased as gestation progressed. The total iron-binding capacity is higher in maternal than in umbilical cord blood at delivery; this suggests that little or no ferritin or transferrin is transferred from mother to fetus. Mother and fetus appear to have independent systems controlling iron metabolism. Transferrin was localized on the site facing the intervillous space, on the surface of the microvilli of the syncytiotrophoblasts. The removal of transferrin from the surface of the trophoblast by thiocyanate and its rebinding were demonstrated. Ferritin was shown to be present in all layers of the trophoblast and especially in the syncytiotrophoblast.
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PMID:The role of transferrin and ferritin in the fetal-maternal-placental unit. 400 78


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