Regulatory networks for the control of body iron homeostasis and their dysregulation in HFE mediated hemochromatosis

J Cell Physiol. 2005 Aug;204(2):489-99. doi: 10.1002/jcp.20315.

Abstract

Although the recent identification of several genes has extended our knowledge on the maintenance of body iron homeostasis, their tissue specific expression patterns and the underlying regulatory networks are poorly understood. We studied C57black/Sv129 mice and HFE knockout (HFE -/-) variants thereof as a model for hemochromatosis, and investigated the expression of iron metabolism genes in the duodenum, liver, and kidney as a function of dietary iron challenge. In HFE +/+ mice dietary iron supplementation increased hepatic expression of hepcidin which was paralleled by decreased iron regulatory protein (IRP) activity, and reduced expression of divalent metal transporter-1 (DMT-1) and duodenal cytochrome b (Dcytb) in the enterocyte. In HFE -/- mice hepcidin formation was diminished upon iron challenge which was associated with decreased hepatic transferrin receptor (TfR)-2 levels. Accordingly, HFE -/- mice presented with high duodenal Dcytb and DMT-1 levels, and increased IRP and TfR expression, suggesting iron deficiency in the enterocyte and increased iron absorption. In parallel, HFE -/- resulted in reduced renal expression of Dcytb and DMT-1. Our data suggest that the feed back regulation of duodenal iron absorption by hepcidin is impaired in HFE -/- mice, a model for genetic hemochromatosis. This change may be linked to inappropriate iron sensing by the liver based on decreased TfR-2 expression, resulting in reduced circulating hepcidin levels and an inappropriate up-regulation of Dcytb and DMT-1 driven iron absorption. In addition, iron excretion/reabsorption by the kidneys may be altered, which may aggravate progressive iron overload.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antimicrobial Cationic Peptides / metabolism
  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism
  • Cytochromes b / genetics
  • Cytochromes b / metabolism
  • Duodenum / metabolism
  • Hemochromatosis / metabolism*
  • Hemochromatosis Protein
  • Hepcidins
  • Histocompatibility Antigens Class I / metabolism*
  • Homeostasis*
  • Iron / metabolism*
  • Iron, Dietary / pharmacology
  • Iron-Binding Proteins / genetics
  • Iron-Binding Proteins / metabolism
  • Iron-Regulatory Proteins / metabolism
  • Kidney / metabolism
  • Liver / metabolism
  • Male
  • Membrane Proteins / deficiency
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • RNA, Messenger / metabolism
  • Receptors, Transferrin / genetics
  • Receptors, Transferrin / metabolism

Substances

  • Antimicrobial Cationic Peptides
  • Cation Transport Proteins
  • Hamp protein, mouse
  • Hemochromatosis Protein
  • Hepcidins
  • Hfe protein, mouse
  • Histocompatibility Antigens Class I
  • Iron, Dietary
  • Iron-Binding Proteins
  • Iron-Regulatory Proteins
  • Membrane Proteins
  • RNA, Messenger
  • Receptors, Transferrin
  • solute carrier family 11- (proton-coupled divalent metal ion transporters), member 2
  • Cytochromes b
  • Iron