Regulation and Function of the Rhomboid Pseudoproteases iRhom1 and iRhom2 in Lung Inflammation

菱形伪蛋白酶 iRhom1 和 iRhom2 在肺部炎症中的调节和功能

• 批准号: 418426903
• 负责人: Professor Dr. Andreas Ludwig
• 金额: --
• 依托单位: Institut für Molekulare Pharmakologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/418426903?language=en
• 关键词: Regulation; Function; Rhomboid; Pseudoproteases; iRhom1

Lung inflammation can be critically modulated by limited proteolysis of cell surface molecules. These so called shedding processes regulate vascular permeability, edema formation, leukocyte recruitment, inflammatory mediator production and fibrotic responses. This involves the activity of several surface molecules such as TNF, EGF family members, IL-6 receptor, transmembrane chemokines, junctional cell adhesion molecules, or syndecans which all undergo shedding by the metalloprotease ADAM17. By cell specific knockout or pharmacological inhibition of ADAM17 we have demonstrated a critical role of endothelial and smooth muscle expressed ADAM17 in a murine model of acute lung inflammation. ADAM17 is known to be tightly regulated by several mechanism. Transcriptional induction of the protease is per se not sufficient and requires further translational events including the trafficking from the ER to the Golgi, maturation and surface expression of the protease. It became clear that these events strictly depend on the interaction of ADAM17 with the rhomboid like pseudoproteases (iRhom1 and 2). We recently observed differential induction of iRhom2 by inflammatory stimuli and iRhom1 by flow conditions. We could show that inflammatory upregulation of endothelial iRhom2 causes enhanced maturation and surface expression of ADAM17. On the other hand upregulation of iRhom1 in flow exposed endothelial cells correlated with enhanced induction and surface expression of ADAM15. We propose that the upregulation of iRhom2 in lung tissue plays a critical role in boosting the inflammatory response, while high expression of iRhom1 could be more important in maintaining some surface expression of ADAM proteases under non-inflammatory conditions. The central aim of this proposal is to study the role of iRhom1 and 2 in lung inflammation at molecular, cellular and systemic levels. The in vitro investigations address the differential role of iRhoms in inflammatory and physiological responses of primary lung cell types including endothelial and smooth muscle cells. This comprises endothelial barer function, permeability changes, mediator production, smooth muscle transactivation, leukocyte transmigration and protection against apoptosis. We observed that in inflamed mouse lungs iRhom2 rather than iRhom1 becomes upregulated. We therefore want to further investigate and correlate the time kinetics of iRhom regulation with the inflammatory events in our model of LPS induced inflammation. We will then use or generate new mice with knockout of iRhom1 and/or 2 or iRhom2 overexpression and investigate them for vascular permeability, mediator production, leukocyte recruitment and fibrotic responses. We expect that our findings allow a deeper understanding of the pathways promoting pathogenic functions of ADAM17 which in turn could support the rationale to target iRhom2 in inflammatory lung diseases.

肺部炎症可以通过细胞表面分子有限的蛋白分解进行关键的调节。这些所谓的脱落过程调节血管的通透性、水肿的形成、白细胞的募集、炎症介质的产生和纤维化反应。这涉及到几个表面分子的活性，如肿瘤坏死因子、EGF家族成员、IL-6受体、跨膜趋化因子、连接细胞黏附分子或突触蛋白，这些分子都经历了金属蛋白酶ADAM17的脱落。通过对ADAM17的细胞特异性敲除或药物抑制，我们证明了血管内皮细胞和血管内皮细胞表达的ADAM17在小鼠急性肺炎症模型中的关键作用。众所周知，ADAM17受到几种机制的严格调控。蛋白水解酶的转录诱导本身是不够的，需要更多的翻译事件，包括从内质网到高尔基体的运输，酶的成熟和表面表达。很明显，这些事件严格依赖于ADAM17与菱形假蛋白水解酶(IRHOM1和2)的相互作用。我们最近观察到炎症刺激对IRHOM2和血流条件对IRHOM1的不同诱导。我们可以证明，内皮IRHOM2的炎性上调导致ADAM17的成熟和表面表达增强。另一方面，血流暴露的内皮细胞中IRHOM1的上调与ADAM15的诱导和表面表达增强相关。我们认为，肺组织中IRHOM2的上调在促进炎症反应中起关键作用，而IRHOM1的高表达可能在非炎症条件下维持ADAM蛋白酶的某些表面表达方面起更重要的作用。这项建议的中心目标是从分子、细胞和系统水平研究IRHOM1和2在肺部炎症中的作用。体外研究探讨了IRHOS在包括内皮细胞和平滑肌细胞在内的原代肺细胞类型的炎症和生理反应中的不同作用。这包括内皮细胞的功能、通透性的变化、介质的产生、平滑肌的激活、白细胞的迁移和对细胞凋亡的保护。我们观察到，在发炎的小鼠肺中，IRHOM2而不是IRHOM1表达上调。因此，我们希望在我们的内毒素诱导的炎症模型中进一步研究iRhom调节的时间动力学和炎症事件之间的关系。然后，我们将使用或产生IRHOM1和/或2或IRHOM2过表达敲除的新小鼠，并研究它们的血管通透性、介质产生、白细胞募集和纤维化反应。我们希望我们的发现能够更深入地了解促进ADAM17致病功能的途径，这反过来可能支持在炎症性肺部疾病中靶向IRHOM2的理论基础。