Regulated intramembrane proteolysis of transferrin receptor 1 and the role of the released intracellular domain in singaling of iron metabolism

要了解血色素沉着症和其他铁代谢疾病的发病机制，需要了解维持全身铁稳态的分子调控机制。转铁蛋白受体1(TfR1)调节细胞对铁的摄取。它的胞外区被释放到血清中。到目前为止，TfR1的这种可溶性形式还没有被赋予功能，强调位于细胞内的TfR1-N末端片段的作用。正如我们的初步工作所显示的，细胞内片段被膜内裂解酶(I-CLIP)进一步切割。膜内蛋白分解促进细胞内信号分子和转录因子的释放。因此，该项目的目的是表征TfR1膜内蛋白分解和释放的胞内结构域(ICD)在系统铁稳态的分子调控中的作用。这将通过鉴定I-Clip-蛋白水解酶、研究蛋白分解的调节以及ICD贩运和最终定位来实现。此外，确定相关隔间内的互动伙伴是非常重要的。因此，ICD将通过蛋白酶体抑制和重组表达而积累。

The understanding of the pathogenesis of hemochromatosis and other diseases of iron metabolism requires knowledge of the molecular regulation mechanism to retain systemic iron homeostasis. Transferrin receptor 1 (TfR1) regulates iron uptake into the cell. Ist ectodomain is released into the serum. As far as is known no function has been assigned to this soluble form of TfR1 to date emphasizing the role of the intracellular located TfR1-N-terminal fragment. As shown in our peliminary work, the intracellular fragment is further cleaved by an intramembrane cleaving protease (I-CLiP). Intramembrane proteolysis promotes the release of intracellular signal molecules and transcription factors. Aim of the project is thus to characterize the role of TfR1 intramembrane proteolysis and of the released intracellular domain (ICD) for the molecular regulation of systemic iron homeostasis. This will be achieved by identification of the I-CLiP-protease, investigations on the regulation of proteolysis as well as by studies on ICD trafficking and ist final localization. Furthermore, identification of interaction partners within the involved compartments is of great importance. Therefore, the ICD will be accumulated by proteasome inhibition and recombinant expression.