title: Human platelets express hemochromatosis protein (HFE) and transferrin receptor 2.
abstract: OBJECTIVE
  While body iron status may influence platelets, little information is available about platelet expression of proteins regulating iron homeostasis. HFE, the protein defective in hereditary hemochromatosis, and transferrin receptor 2 (TfR2) are two novel protein candidates that could be involved in mechanisms of iron transport across the platelet plasma membrane.
  
  
  METHODS
  The expression and localization of HFE, TfR1 and TfR2 proteins in human platelets were examined using Western blotting and immunocytochemistry.
  
  
  RESULTS
  Human platelets expressed HFE and TfR2, whereas no signal for TfR1 was found. The positive reactions for HFE and TfR2 were mainly confined to the platelet plasma membrane.
  
  
  CONCLUSIONS
  Expression of HFE and TfR2 proteins in human platelets may indicate that the mutations in the corresponding genes could influence platelet count, size and/or activation. The presence of TfR2 and absence of TfR1 suggests that HFE may serve a different function in platelets compared with the other HFE-positive cell types, e.g. enterocytes, macrophages and syncytiotrophoblasts.
authors.affiliation: Department of Clinical Chemistry, University of Oulu, Oulu, Finland. jokkeha@paju.oulu.fi
authors.forename: Jokke
authors.initials: J
authors.lastname: Hannuksela
authors.forename: Seppo
authors.initials: S
authors.lastname: Parkkila
authors.forename: Abdul
authors.initials: A
authors.lastname: Waheed
authors.forename: Robert S
authors.initials: RS
authors.lastname: Britton
authors.forename: Robert E
authors.initials: RE
authors.lastname: Fleming
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Bacon
authors.forename: William S
authors.initials: WS
authors.lastname: Sly
mesh_terms: D001792:Blood Platelets / Q000737:chemistry* / Q000166:cytology; D015153:Blotting, Western; D002462:Cell Membrane / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D019084:Fluorescent Antibody Technique, Indirect; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I / Q000097:blood*; D006706:Homeostasis; D006801:Humans; D007501:Iron / Q000097:blood; D008565:Membrane Proteins / Q000097:blood*; D009928:Organ Specificity; D011485:Protein Binding; D011990:Receptors, Transferrin / Q000097:blood*
chemical_list: C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D011990:Receptors, Transferrin; C503640:TFR2 protein, human; D007501:Iron