title: Hereditary hemochromatosis and transferrin receptor 2.
abstract: BACKGROUND
  Multicellular organisms regulate the uptake of calories, trace elements, and other nutrients by complex feedback mechanisms. In the case of iron, the body senses internal iron stores, iron requirements for hematopoiesis, and inflammatory status, and regulates iron uptake by modulating the uptake of dietary iron from the intestine. Both the liver and the intestine participate in the coordination of iron uptake and distribution in the body. The liver senses inflammatory signals and iron status of the organism and secretes a peptide hormone, hepcidin. Under high iron or inflammatory conditions hepcidin levels increase. Hepcidin binds to the iron transport protein, ferroportin (FPN), promoting FPN internalization and degradation. Decreased FPN levels reduce iron efflux out of intestinal epithelial cells and macrophages into the circulation. Derangements in iron metabolism result in either the abnormal accumulation of iron in the body, or in anemias. The identification of the mutations that cause the iron overload disease, hereditary hemochromatosis (HH), or iron-refractory iron-deficiency anemia has revealed many of the proteins used to regulate iron uptake.
  
  
  OBJECTIVE
  In this review we discuss recent data concerning the regulation of iron homeostasis in the body by the liver and how transferrin receptor 2 (TfR2) affects this process.
  
  
  CONCLUSIONS
  TfR2 plays a key role in regulating iron homeostasis in the body.
  
  
  CONCLUSIONS
  The regulation of iron homeostasis is important. One third of the people in the world are anemic. HH is the most common inherited disease in people of Northern European origin and can lead to severe health complications if left untreated. This article is part of a Special Issue entitled Transferrins: Molecular mechanisms of iron transport and disorders.
authors.affiliation: Department of Cell and Developmental Biology L215, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, USA.
authors.forename: Juxing
authors.initials: J
authors.lastname: Chen
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Enns
mesh_terms: D018798:Anemia, Iron-Deficiency / Q000235:genetics / Q000378:metabolism; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000378:metabolism; D004920:Erythropoiesis / Q000235:genetics; D006432:Hemochromatosis / Q000235:genetics* / Q000378:metabolism; D064451:Hepcidins; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D017136:Ion Transport; D007501:Iron / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D011990:Receptors, Transferrin / Q000235:genetics* / Q000378:metabolism; D000098742:Ferroportin
chemical_list: D023181:Antimicrobial Cationic Peptides; D027682:Cation Transport Proteins; C578702:HAMP protein, human; D064451:Hepcidins; D011990:Receptors, Transferrin; C503640:TFR2 protein, human; D000098742:Ferroportin; D007501:Iron