The purpose of the study was to investigate the expression of ferroportin protein following treatments that affect systemic hepcidin. Administration of erythropoietin to C57BL/6J mice decreased systemic hepcidin expression; it also increased heart ferroportin protein content, determined by immunoblot in the membrane fraction, to approximately 200% of control values. This increase in heart ferroportin protein is very probably caused by a decrease in systemic hepcidin expression, in accordance with the classical regulation of ferroportin by hepcidin. However, the control of heart ferroportin protein by systemic hepcidin could apparently be overridden by changes in heart non-heme iron content since injection of ferric carboxymaltose to mice at 300 mg Fe/kg resulted in an increase in liver hepcidin expression, heart non-heme iron content, and also a threefold increase in heart ferroportin protein content. In a separate experiment, feeding an iron-deficient diet to young Wistar rats dramatically decreased liver hepcidin expression, while heart non-heme iron content and heart ferroportin protein content decreased to 50% of controls. It is, therefore, suggested that heart ferroportin protein is regulated primarily by the iron regulatory protein/iron-responsive element system and that the regulation of heart ferroportin by the hepcidin-ferroportin axis plays a secondary role.

• Keywords
• ferroportin, hemojuvelin, hepcidin, iron metabolism, myocardium,
• MeSH
• Ferroportin MeSH
• Hepcidins * genetics   metabolism   MeSH
• Rats MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Rats, Wistar MeSH
• Cation Transport Proteins MeSH
• Iron * metabolism   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Ferroportin MeSH
• Hepcidins * MeSH
• Cation Transport Proteins MeSH
• Iron * MeSH

Duodenal biopsies are considered a suitable source of enterocytes for studies of dietary iron absorption. However, the expression level of molecules involved in iron absorption may vary along the length of duodenum. We aimed to determine whether the expression of molecules involved in the absorption of heme and non-heme iron differs depending on the location in the duodenum. Analysis was performed with samples of duodenal biopsies from 10 individuals with normal iron metabolism. Samples were collected at the following locations: (a) immediately post-bulbar, (b) 1-2 cm below the papilla of Vater and (c) in the distal duodenum. The gene expression was analyzed at the mRNA and protein level using real-time PCR and Western blot analysis. At the mRNA level, significantly different expression of HCP1, DMT1, ferroportin and Zip8 was found at individual positions of duodenum. Position-dependent expression of other molecules, especially of FLVCR1, HMOX1 and HMOX2 was also detected but with no statistical significances. At the protein level, we observed statistically significantly decreasing expression of transporters HCP1, FLVCR1, DMT1, ferroportin, Zip14 and Zip8 with advancing positions of duodenum. Our results are consistent with a gradient of diminishing iron absorption along the duodenum for both heme and non-heme iron.

• Keywords
• heme iron absorption, iron transport, iron uptake in duodenum, non-heme iron absorption,
• MeSH
• Duodenum * metabolism   MeSH
• Heme metabolism   MeSH
• Ion Transport MeSH
• Humans MeSH
• RNA, Messenger genetics   metabolism   MeSH
• Iron * metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Heme MeSH
• RNA, Messenger MeSH
• Iron * MeSH

BACKGROUND: Hypochromic microcytic anemia associated with ineffective erythropoiesis caused by recessive mutations in divalent metal transporter 1 (DMT1) can be improved with high-dose erythropoietin supplementation. The aim of this study was to characterize and compare erythropoiesis in samples from a DMT1-mutant patient before and after treatment with erythropoietin, as well as in a mouse model with a DMT1 mutation, the mk/mk mice. DESIGN AND METHODS: Colony assays were used to compare the in vitro growth of pre-treatment and post-treatment erythroid progenitors in a DMT1-mutant patient. To enable a comparison with human data, high doses of erythropoietin were administered to mk/mk mice. The apoptotic status of erythroblasts, the expression of anti-apoptotic proteins, and the key components of the bone marrow-hepcidin axis were evaluated. RESULTS: Erythropoietin therapy in vivo or the addition of a broad-spectrum caspase inhibitor in vitro significantly improved the growth of human DMT1-mutant erythroid progenitors. A decreased number of apoptotic erythroblasts was detected in the patient's bone marrow after erythropoietin treatment. In mk/mk mice, erythropoietin administration increased activation of signal transducer and activator of transcription 5 (STAT5) and reduced apoptosis in bone marrow and spleen erythroblasts. mk/mk mice propagated on the 129S6/SvEvTac background resembled DMT1-mutant patients in having increased plasma iron but differed by having functional iron deficiency after erythropoietin administration. Co-regulation of hepcidin and growth differentiation factor 15 (GDF15) levels was observed in mk/mk mice but not in the patient. CONCLUSIONS: Erythropoietin inhibits apoptosis of DMT1-mutant erythroid progenitors and differentiating erythroblasts. Ineffective erythropoiesis associated with defective erythroid iron utilization due to DMT1 mutations has specific biological and clinical features.

• MeSH
• Apoptosis drug effects   genetics   MeSH
• Erythropoietin administration & dosage   pharmacology   MeSH
• Erythroblasts drug effects   metabolism   MeSH
• Erythrocyte Indices MeSH
• Erythroid Precursor Cells drug effects   metabolism   MeSH
• Hepcidins MeSH
• Anemia, Hypochromic drug therapy   genetics   metabolism   MeSH
• Caspases metabolism   MeSH
• Antimicrobial Cationic Peptides metabolism   MeSH
• Bone Marrow drug effects   metabolism   MeSH
• Humans MeSH
• Mutation * MeSH
• Mice, Knockout MeSH
• Mice MeSH
• Cation Transport Proteins genetics   MeSH
• Signal Transduction drug effects   MeSH
• Cell Survival drug effects   genetics   MeSH
• Iron metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Erythropoietin MeSH
• HAMP protein, human MeSH Browser
• Hamp protein, mouse MeSH Browser
• Hepcidins MeSH
• Caspases MeSH
• Antimicrobial Cationic Peptides MeSH
• Cation Transport Proteins MeSH
• solute carrier family 11- (proton-coupled divalent metal ion transporters), member 2 MeSH Browser
• Iron MeSH

We studied the effect of iron deficiency, i.e., 24-h preincubation in iron-free medium, and the effect of high level of non-transferrin iron, i.e., the preincubation in ferric citrate medium containing 500 microM ferric citrate, on the expression of DMT1, Dcytb, ferroportin, hephaestin, and ceruloplasmin in various functional types of human cells. The expression of these proteins potentially involved in non-transferrin iron transport across cell membranes was tested on mRNA level by quantitative real-time PCR as well as on protein level by western blot analysis in Caco-2 (colorectal carcinoma), K562 (erythroleukemia), and HEP-G2 (hepatocellular carcinoma) cells. We found that changes in non-transferrin iron availability, i.e., iron deficiency and high level of non-transferrin iron, affect the expression of tested proteins in a cell type-specific manner. We also demonstrated that changes in the expression on mRNA level do not often correlate with relevant changes on protein level.

• MeSH
• Cell Membrane metabolism   MeSH
• Cell Line MeSH
• Ceruloplasmin genetics   metabolism   MeSH
• Cytochrome b Group genetics   metabolism   MeSH
• Gene Expression * MeSH
• Ferroportin MeSH
• Culture Media chemistry   MeSH
• Humans MeSH
• Membrane Proteins * genetics   metabolism   MeSH
• Oxidoreductases genetics   metabolism   MeSH
• Cation Transport Proteins genetics   metabolism   MeSH
• Transferrin metabolism   MeSH
• Iron metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Ceruloplasmin MeSH
• CYBRD1 protein, human MeSH Browser
• Cytochrome b Group MeSH
• Ferroportin MeSH
• HEPH protein, human MeSH Browser
• Culture Media MeSH
• Membrane Proteins * MeSH
• Oxidoreductases MeSH
• Cation Transport Proteins MeSH
• solute carrier family 11- (proton-coupled divalent metal ion transporters), member 2 MeSH Browser
• Transferrin MeSH
• Iron MeSH