Protein HFE is a member of the major histocompatibility complex class I-like family and a negative regulator of iron absorption. Mutations in the gene encoding HFE cause hereditary hemochromatosis (HH), a hereditary disease characterised by excessive intestinal absorption of dietary iron resulting in a pathological increase in total body iron stores []. HFE interacts with transferrin receptor (TFR), a key protein involved in iron transport. An alteration in this regulatory mechanism could play a role in the pathogenesis of hereditary hemochromatosis [].HFE, while structurally homologous to MHC I, is unable to bind peptides []. However, several lines of evidence indicate that the role of HFE may extend toward a role inimmunity. HFE may influence antigen presentation [, ]. Furthermore, HFE appears to inhibit antigen-specific CD8(+) T-lymphocyte activation, probably due to altered intracellular processing of MHC I antigens [].HFE gene variants correlate with body iron levels and have shown association with cancer risk, including childhood acute lymphoblastic leukemia [, ].
Hemojuvelin, also called repulsive guidance molecule C or Hfe2, is a GPI-linked membrane protein essential for iron homeostasis []. Hemojuvelin is a bone morphogenetic protein (BMP) coreceptor; it regulates iron homeostasis by interacting with BMP ligands to induce hepcidin expression []. It forms a membrane-associated protein complex with HFE and the transferrin receptor 2 for hepcidin regulation [].
