Duodenal expression of iron transport molecules in untreated haemochromatosis subjects

• Published in: Gut Vol. 52; no. 7; pp. 953 - 959
• Main Authors: Stuart, K A, Anderson, G J, Frazer, D M, Powell, L W, McCullen, M, Fletcher, L M, Crawford, D H G
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and British Society of Gastroenterology 01.07.2003; BMJ; BMJ Publishing Group LTD; Copyright 2003 by Gut
• Subjects: Adolescent; Adult; Aged; Biological and medical sciences; Biological Transport - physiology; Biopsy; Cation Transport Proteins - analysis; Cytochrome b Group - analysis; Dcytb; divalent metal transporter 1; DMT1; duodenal cytochrome-b; Duodenum - metabolism; Enzymes; Female; Ferritins - blood; GAPDH; Genes; glyceraldehyde-3-phosphate dehydrogenase; haemochromatosis; Hemochromatosis - metabolism; hephaestin; hereditary haemochromatosis; HHC; Hospitals; Humans; IRE; Ireg1; Iron; iron deficiency; iron regulated gene 1; iron responsive element; Iron-Binding Proteins - analysis; Iron-Binding Proteins - blood; Iron-Binding Proteins - metabolism; Iron-Regulatory Proteins - genetics; Male; Medical research; Medical sciences; Membrane Proteins - analysis; Metabolic diseases; Metals (hemochromatosis...); Middle Aged; Mutation; Other metabolic disorders; Proteins; ribonuclease protection assay; RNA - analysis; Rodents; RPA; serum ferritin concentration; Small Intestine; Studies; transferrin saturation; untranslated region; Up-Regulation - physiology; UTR; Human; Immunopathology; Hemochromatosis; Duodenal disease; Duodenum; Metabolic diseases; Iron; Gene expression; Hereditary; Enzymopathy; Molecules; Messenger RNA; Biopsy; Clinical biology; Digestive diseases; Genetics; Transport
• DOI: 10.1136/gut.52.7.953
• ISSN: 0017-5749

Background and aims: In HFE associated hereditary haemochromatosis, the duodenal enterocyte behaves as if iron deficient and previous reports have shown increased duodenal expression of divalent metal transporter 1 (DMT1) and iron regulated gene 1 (Ireg1) in affected subjects. In those studies, many patients had undergone venesection, which is a potent stimulus of iron absorption. Our study investigated duodenal expression of DMT1 (IRE and non-IRE), Ireg1, hephaestin, and duodenal cytochrome-b (Dyctb) in untreated C282Y homozygous haemochromatosis patients, iron deficient patients, and iron replete subjects. Methods: Total RNA was extracted from duodenal biopsies and expression of the iron transport genes was assessed by ribonuclease protection assay. Results: Expression of DMT1 (IRE) and Ireg1 was increased 3–5-fold in iron deficient subjects compared with iron replete subjects. Duodenal expression of DMT1 (IRE) and Ireg1 was similar in haemochromatosis patients and iron replete subjects but in haemochromatosis patients with elevated serum ferritin concentrations, both DMT1 (IRE) and Ireg1 expression were inappropriately increased relative to serum ferritin concentration. Hephaestin and Dcytb levels were not upregulated in haemochromatosis. DMT1 (IRE) and Ireg1 levels showed significant inverse correlations with serum ferritin concentration in each group of patients. Conclusions: These findings are consistent with DMT1 (IRE) and Ireg1 playing primary roles in the adaptive response to iron deficiency. Untreated haemochromatosis patients showed inappropriate increases in DMT1 (IRE) and Ireg1 expression for a given level of serum ferritin concentration, although the actual level of expression of these iron transport genes was not significantly different from that of normal subjects.