Characterisation of the co-adapter function of the E3 ligase Neuralized (Neur) during DSL-ligand induced Notch signalling

DSL 配体诱导 Notch 信号传导过程中 E3 连接酶神经化 (Neur) 的辅助适配器功能的表征

• 批准号: 501110669
• 负责人: Professor Dr. Thomas Klein
• 金额: --
• 依托单位: Institut für Genetik
• 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/501110669?language=en
• 关键词: Characterisation; co; adapter; function; E3

Notch signalling plays a crucial role in many developmental processes in all metazoans. Moreover, it is required for homeostasis of several adult tissues, including in humans, through its involvement in maintenance of adult stem cells. Endocytosis is required for the full ligand induced activation of the pathway. It is initiated by the membrane-associated E3 ligases Neuralized (Neur) and Mindbomb1 (Mib1). They bind to the intracellular domains (ICDs) of DSL ligands to mediate the ubiquitylation (ubi) on lysine (K) side chains. The ubiquitylated ligands are recognised by the endocytic adapter Liquid Facets (Lqf)/Epsin via its ubiquitin binding domains and thereby connected to the endocytic core machinery. In Drosophila, the two E3 ligases can functionally substitute for one another during wing development, indicating that they can perform similar functions, even though they share no sequence similarity apart from a RING (Really Interesting New Gene) Finger domain (RF), which is required for ubi. However, Mib1 cannot replace the function of Neur during neurogenesis, suggesting that Neur can initiate Notch signalling in a manner different from Mib1. Our recent work supports this notion by revealing that ligands that cannot be ubiquitylated can be activated by Neur, but not Mib1. Hence, Neur has another so far unknown function despite its E3 ligase activity, which cannot be provided by Mib1. In this application, we will further characterise the function of Neur and follow the hypothesis that Neur is a novel type of endocytic co-adapter that forms a complex with Lqf/Epsin to connect the ligands in an additional way to the core endocytic machinery.

Notch信号在所有后生动物的许多发育过程中起着至关重要的作用。此外，通过参与维持成体干细胞，它是几种成体组织（包括人类）的稳态所必需的。胞吞作用是完全配体诱导的途径活化所必需的。它由膜相关的E3连接酶Neuralized（Neur）和Mindbomb 1（Mib 1）启动。它们与DSL配体的胞内结构域（ICD）结合以介导赖氨酸（K）侧链上的泛素化（ubi）。泛素化配体通过其泛素结合结构域被内吞衔接子液体小面（Lqf）/Epsin识别，从而连接到内吞核心机制。在果蝇中，两种E3连接酶在翅膀发育过程中可以在功能上相互替代，表明它们可以执行类似的功能，即使它们除了UBI所需的RING（真正有趣的新基因）指状结构域（RF）之外没有序列相似性。然而，Mib 1在神经发生过程中不能取代Neur的功能，这表明Neur可以以不同于Mib 1的方式启动Notch信号传导。我们最近的工作通过揭示不能被泛素化的配体可以被Neur激活而不是Mib 1来支持这一观点。因此，尽管Neur具有Mib 1不能提供的E3连接酶活性，但它具有另一种迄今未知的功能。在本申请中，我们将进一步验证Neur的功能，并遵循Neur是一种新型的内吞共适体的假设，其与Lqf/Epsin形成复合物，以另外的方式将配体连接到核心内吞机制。