title: In situ proximity ligation assays indicate that hemochromatosis proteins Hfe and transferrin receptor 2 (Tfr2) do not interact.
abstract: The hemochromatosis associated proteins HFE and Transferrin Receptor 2 (TFR2) have been shown to be important for the proper regulation of hepcidin. A number of in vitro studies using transient overexpression systems have suggested that an interaction between HFE and TFR2 is required for the regulation of hepcidin. This model of iron sensing which centers upon the requirement for an interaction between HFE and TFR2 has recently been questioned with in vivo studies in mice from our laboratory and others which suggest that Hfe and Tfr2 can regulate hepcidin independently of each other. To re-examine the postulated interaction between Hfe and Tfr2 we developed a novel expression system in which both proteins are stably co-expressed and used the proximity ligation assay to examine the interactions between Hfe, Tfr1 and Tfr2 at a cellular level. We were able to detect the previously described interaction between Hfe and Tfr1, and heterodimers between Tfr1 and Tfr2; however no interaction between Hfe and Tfr2 was observed in our system. The results from this study indicate that Hfe and Tfr2 do not interact with each other when they are stably expressed at similar levels. Furthermore, these results support in vivo studies which suggest that Hfe and Tfr2 can independently regulate hepcidin.
authors.affiliation: The Membrane Transport Laboratory, the Queensland Institute of Medical Research, Queensland, Australia ; Liver Research Centre, School of Medicine, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Gautam
authors.initials: G
authors.lastname: Rishi
authors.forename: Emily M
authors.initials: EM
authors.lastname: Crampton
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Wallace
authors.forename: V Nathan
authors.initials: VN
authors.lastname: Subramaniam
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001681:Biological Assay / Q000379:methods*; D045744:Cell Line, Tumor; D006432:Hemochromatosis / Q000378:metabolism*; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D011485:Protein Binding; D021381:Protein Transport; D011990:Receptors, Transferrin / Q000378:metabolism*; D014162:Transfection
chemical_list: D015703:Antigens, CD; C068126:CD71 antigen; D000071020:Hemochromatosis Protein; C499535:Hfe protein, mouse; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D011990:Receptors, Transferrin; C503641:TFR2 protein, mouse