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  • Regulation of iron homeosta...
    Xiao, Xia; Moschetta, Gillian A.; Xu, Yang; Fisher, Allison L.; Alfaro-Magallanes, Víctor M.; Dev, Som; Wang, Chia-Yu; Babitt, Jodie L.

    Blood, 01/2023, Letnik: 141, Številka: 4
    Journal Article

    •Hepatocyte TfR1 requires HFE for its role in hepcidin regulation and iron homeostasis.•Hepatocyte TfR1 restrains hepcidin induction by serum iron and promotes hepcidin suppression and iron overload in β-thalassemia. Display omitted Transferrin receptor 1 (TfR1) performs a critical role in cellular iron uptake. Hepatocyte TfR1 is also proposed to influence systemic iron homeostasis by interacting with the hemochromatosis protein HFE to regulate hepcidin production. Here, we generated hepatocyte Tfrc knockout mice (Tfrcfl/fl;Alb-Cre+), either alone or together with Hfe knockout or β-thalassemia, to investigate the extent to which hepatocyte TfR1 function depends on HFE, whether hepatocyte TfR1 impacts hepcidin regulation by serum iron and erythropoietic signals, and its contribution to hepcidin suppression and iron overload in β-thalassemia. Compared with Tfrcfl/fl;Alb-Cre− controls, Tfrcfl/fl;Alb-Cre+ mice displayed reduced serum and liver iron; mildly reduced hematocrit, mean cell hemoglobin, and mean cell volume; increased erythropoietin and erythroferrone; and unchanged hepcidin levels that were inappropriately high relative to serum iron, liver iron, and erythroferrone levels. However, ablation of hepatocyte Tfrc had no impact on iron phenotype in Hfe knockout mice. Tfrcfl/fl;Alb-Cre+ mice also displayed a greater induction of hepcidin by serum iron compared with Tfrcfl/fl;Alb-Cre− controls. Finally, although acute erythropoietin injection similarly reduced hepcidin in Tfrcfl/fl;Alb-Cre+ and Tfrcfl/fl;Alb-Cre− mice, ablation of hepatocyte Tfrc in a mouse model of β-thalassemia intermedia ameliorated hepcidin deficiency and liver iron loading. Together, our data suggest that the major nonredundant function of hepatocyte TfR1 in iron homeostasis is to interact with HFE to regulate hepcidin. This regulatory pathway is modulated by serum iron and contributes to hepcidin suppression and iron overload in murine β-thalassemia. Hepcidin is the master regulator of systemic iron homeostasis. Using genetically manipulated murine models, Xiao and colleagues reveal that hepatocyte transferrin receptor 1 (TfR1) restrains hepcidin induction by serum iron and promotes hepcidin suppression and iron overload in β-thalassemia. The authors prove that TfR1 action is dependent upon HFE, the product of the most commonly mutated gene in hereditary hemochromatosis, adding important detail to our knowledge of iron regulation.