title: Transgenic HFE-dependent induction of hepcidin in mice does not require transferrin receptor-2.
abstract: Hereditary hemochomatosis (HH) is caused by mutations in several genes, including HFE and transferrin receptor-2 (TFR2). Loss of either protein decreases expression of the iron regulatory hormone hepcidin by the liver, leading to inappropriately high iron uptake from the diet, and resulting in systemic iron overload. In tissue culture, overexpressed HFE and TFR2 physically interact. Hepatocellular overexpression of Hfe in vivo increases hepcidin expression, despite an associated decrease in Tfr2. On this basis, we hypothesized that Tfr2 would not be required for Hfe-dependent up-regulation of hepcidin. We show that hepatocellular overexpression of Hfe in Tfr2(Y245X/Y245X) mice leads to hepcidin induction eventuating in iron deficiency and a hypochromic, microcytic anemia. Furthermore, coimmunoprecipitation studies using liver lysates did not provide evidence for physical interaction between Hfe and Tfr2 in vivo. In conclusion, we demonstrate that Tfr2 is not essential for Hfe-mediated induction of hepcidin expression, supporting the possibility that TFR2 may regulate iron metabolism in an HFE-independent manner.
authors.affiliation: Department of Pathology, Children's Hospital Boston and Harvard Medical School, 320 Longwood Ave., Boston, MA 02115, USA. pschmidt@enders.tch.harvard.edu
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Schmidt
authors.forename: Mark D
authors.initials: MD
authors.lastname: Fleming
mesh_terms: D000747:Anemia, Hypochromic / Q000235:genetics; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis* / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism; D005786:Gene Expression Regulation; D005813:Genes, Synthetic; D000071020:Hemochromatosis Protein; D064451:Hepcidins; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000502:physiology*; D007501:Iron / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D020125:Mutation, Missense; D010641:Phenotype; D017354:Point Mutation; D011228:Prealbumin / Q000235:genetics; D011485:Protein Binding; D011990:Receptors, Transferrin / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013154:Spleen / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000172:deficiency / Q000235:genetics
chemical_list: D023181:Antimicrobial Cationic Peptides; C579599:Hamp protein, mouse; D000071020:Hemochromatosis Protein; D064451:Hepcidins; C499535:Hfe protein, mouse; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D011228:Prealbumin; D011990:Receptors, Transferrin; D011993:Recombinant Fusion Proteins; C503641:TFR2 protein, mouse; C480029:Tfrc protein, mouse; D001613:beta 2-Microglobulin; D007501:Iron