Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; Department of Pediatric Oncology, Hematology and Immunology, University Hospital Heidelberg, Heidelberg, Germany.
Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
Biochim Biophys Acta Gen Subj. 2021 Mar;1865(3):129829. doi: 10.1016/j.bbagen.2020.129829. Epub 2020 Dec 16.
Iron export via the transport protein ferroportin (Fpn) plays a critical role in the regulation of dietary iron absorption and iron recycling in macrophages. Fpn plasma membrane expression is controlled by the hepatic iron-regulated hormone hepcidin in response to high iron availability and inflammation. Hepcidin binds to the central cavity of the Fpn transporter to block iron export either directly or by inducing Fpn internalization and lysosomal degradation. Here, we investigated whether iron deficiency affects Fpn protein turnover.
We ectopically expressed Fpn in HeLa cells and used cycloheximide chase experiments to study basal and hepcidin-induced Fpn degradation under extracellular and intracellular iron deficiency.
CONCLUSIONS/GENERAL SIGNIFICANCE: We show that iron deficiency does not affect basal Fpn turnover but causes a significant delay in hepcidin-induced degradation when cytosolic iron levels are low. These data have important mechanistic implications supporting the hypothesis that iron export is required for efficient targeting of Fpn by hepcidin. Additionally, we show that Fpn degradation is not involved in protecting cells from intracellular iron deficiency.
通过转运蛋白铁输出蛋白（Fpn）进行铁输出，在调节膳食铁吸收和巨噬细胞内铁再循环方面起着关键作用。Fpn 质膜表达受肝铁调节激素铁调素（hepcidin）控制，以响应高铁可用性和炎症。hepcidin 与 Fpn 转运体的中央腔结合，通过直接或诱导 Fpn 内化和溶酶体降解来阻断铁输出。在这里，我们研究了铁缺乏是否影响 Fpn 蛋白周转。
我们在 HeLa 细胞中转染表达 Fpn，并使用环己酰亚胺追踪实验研究细胞外和细胞内铁缺乏时基础和 hepcidin 诱导的 Fpn 降解。
结论/一般意义：我们表明，铁缺乏不会影响基础 Fpn 周转，但当细胞内铁水平较低时，会显著延迟 hepcidin 诱导的降解。这些数据具有重要的机制意义，支持铁输出对于 hepcidin 有效靶向 Fpn 的假说。此外，我们还表明，Fpn 降解不参与保护细胞免受细胞内铁缺乏的影响。
