Cell biology of signalling: how members of the rhomboid-like superfamily regulate multiple pathways

摘要细胞间通讯是多细胞生物体中的一个重要过程，细胞间通讯的失调会导致严重的后果。虹膜蛋白是一种非活性的假蛋白水解酶，是类菱形超家族的一员。它们位于内质网(ER)，参与细胞间信号转导。由于iRhom介导了果蝇ERAD系统(内质网相关降解)对EGFR(表皮生长因子受体)配体的降解，因此它是EGFR途径的负调节因子。另一方面，在哺乳动物中有两个IRHOs(IRHOM1和IRHOM2)，它们通过调节跨膜蛋白ADAM17(A去整合素和金属蛋白酶)的运输和成熟而发挥正向调节作用。ADAM17具有巨大的底物多样性，因此参与了许多生理和病理生理过程，如再生和发育，但也参与慢性炎症和肿瘤的发展。这是因为在其他底物中，EGFR和细胞因子的配体是由ADAM17蛋白水解性释放的。这证明了ADAM17调控的重要性，从而证明了IRHMA对于细胞间信号传递的重要性。目前还不清楚iRhom介导的ADAM17贩运的潜在机制，也不知道除了ADAM17贩运之外是否还有其他iRhom功能。因此，拟议项目的目标将是描述人类IRHOM1和人类IRHOM2的特征。该项目分为三个部分：1.研究ADAM17和IRHOMS之间的相互作用；2.保守的IRHOM结构域的结构和功能特征；3.细胞质区域的功能特征和该区域相互作用伙伴的鉴定

Summary Communication between cells is an important process in multicellular organisms and a dysregulation of the intercellular communication can have a severe outcome. iRhoms (inactive rhomboids) are inactive pseudoproteases and members of the rhomboid-like superfamily. They are located in the Endoplasmic reticulum (ER) and involved in intercellular signalling. Since iRhom mediates the degradation of ligands of the EGFR (epidermal growth factor receptor) by the ERAD-system (ER-associated degradation) in Drosophila melanogaster, it acts as a negative regulator of the EGFR pathway. On the other hand in mammalians there are two iRhoms (iRhom1 and iRhom2), which act as positive regulators by mediating the trafficking and maturation of the transmembrane protease ADAM17 (A Disintegrin And Metalloproteinase). ADAM17 has a huge substrate variety and therefore is involved in many physiological and pathophysiological processes such as regeneration and development but also chronic inflammation and tumour development. The reason for this is that among other substrates ligands of the EGFR and cytokines are proteolytically released by ADAM17. This demonstrates the importance of an ADAM17 regulation and therefore the significance of iRhoms for intercellular signalling. Neither the underlying mechanism of the iRhom-mediated trafficking of ADAM17 is clear nor is it known, if there are other iRhom functions beyond ADAM17 trafficking. Therefore the aim of the proposed project will be to characterise human iRhom1 and human iRhom2. The project is divided in three parts: 1. Characterising the interaction between ADAM17 and iRhoms 2. Structural and functional characterisation of the conserved luminal iRhom domain 3. Functional characterisation of the cytoplasmic region and identification of interaction partners of this region