Structural Basis of Norrin-induced Wnt/beta-catenin signaling

Norrin 诱导的 Wnt/β-catenin 信号传导的结构基础

• 批准号: 9006448
• 负责人: Wenqing Xu
• 金额: $ 38.63万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9006448
• 关键词: Address; Affect; Binding; Biochemical; Blood Vessels; Body part; Brain; Cell membrane; Cells; Complex; Cysteine-Rich Domain; Development; Dimerization; Disease; Ear; Engineering; Extracellular Space; Eye diseases; FZD4 gene; G-Protein-Coupled Receptors; Genes; Genetic study; Goals; Growth; Homologous Gene; Individual; Intervention; Ligands; Light; Link; Lipids; Mediating; Modification; Mutagenesis; Mutation; Norrie' s disease; Orphan; Pathway interactions; Patients; Play; Post-Translational Protein Processing; Prevention; Property; Proteins; Recombinants; Regenerative Medicine; Retina; Retinal; Retinopathy of Prematurity; Role; Signal Pathway; Signal Transduction; Signaling Protein; Solubility; Stem cells; Structure; Techniques; Therapeutic; Transforming Growth Factor beta; United States; Wnt proteins; Work; X-Ray Crystallography; base; beta catenin; design; extracellular; genetic regulatory protein; insight; mimetics; mutant; novel strategies; prevent; public health relevance; receptor; reconstitution; stem cell biology; three dimensional structure

 DESCRIPTION (provided by applicant): Norrin, also known as the Norrie disease protein or X-linked exudative vitreoretinopathy 2 protein, is a secreted retinal growth factor with angiogenic and neuroprotective properties. Norrin mutations are associated with the Norrie disease, familiar exudative vitreoretinopathy (FEVR), retinopathy of prematurity (ROP), and other retinal hypovascularization diseases. Despite its distinct structure from Wnt proteins, Norrin binds specifically to Frizzled 4 (Fz4), a Wnt receptor, and Lrp5/6, a Wnt co-receptor, and activates the canonical Wnt/-catenin signaling pathway inside the cell. How Norrin activates the Wnt/-catenin signaling pathway through its interactions with Fz4 and Lrp5/6, and how Norrin is regulated by other proteins, remain enigmatic. Here we aim to unravel the structural basis of Norrin-dependent Wnt pathway activation through the determination of the 3D structures of Norrin in complex with Fz4 and/or Lrp5/6, using a combination of X-ray crystallography, cryo-EM and biochemical analysis. We will also provide key clues to understand how Norrin is regulated by Wnt pathway regulators such as Lgr4. Understanding the structural basis of Norrin-induced Wnt pathway activation will not only reveal Norrin signaling mechanism, but also help with the development of new approaches for prevention and/or treatment of retinal hypovascularization diseases that affects about 20 million patients in the United States alone. In addition, in contras to the poor solubility of Wnt proteins due to their essential lipid modification, which prevented their practical uses in therapeutics, recombinant Norrin protein without any posttranslational modification is fully active in activating canonical Wnt signaling. Therefore, our work may also provide a structural template for designing soluble Wnt mimetics useful for stem cell biology and regenerative medicine.

 描述（由申请人提供）：Norrin，也称为诺里病蛋白或X连锁渗出性玻璃体视网膜病变2蛋白，是一种分泌型视网膜生长因子，具有血管生成和神经保护特性。Norrin突变与诺里病、家族性渗出性玻璃体视网膜病变（FEVR）、早产儿视网膜病变（ROP）和其他视网膜血管生成不足疾病相关。尽管Norrin的结构与Wnt蛋白不同，但它特异性结合Wnt受体Frizzled 4（Fz 4）和Wnt共受体Lrp 5/6，并激活细胞内的经典Wnt/β-连环蛋白信号通路。Norrin如何通过与Fz 4和Lrp 5/6的相互作用激活Wnt/β-连环蛋白信号通路，以及Norrin如何被其他蛋白质调节，仍然是个谜。在这里，我们的目标是解开Norrin依赖的Wnt途径激活的结构基础，通过确定的3D结构的Norrin与Fz 4和/或Lrp 5/6，使用X射线晶体学，冷冻EM和生化分析的组合。我们还将提供关键线索，以了解Norrin是如何被Wnt通路调节因子如Lgr 4调节的。了解Norrin诱导的Wnt通路激活的结构基础不仅将揭示Norrin信号传导机制，而且还有助于开发预防和/或治疗视网膜血管生成不足疾病的新方法，仅在美国就影响约2000万患者。此外，与Wnt蛋白由于其必需的脂质修饰而导致的溶解性差相反，这阻碍了它们在治疗中的实际应用，没有任何翻译后修饰的重组Norrin蛋白在激活经典Wnt信号传导中是完全活性的。因此，我们的工作也可能提供一个结构模板，用于设计可溶性Wnt模拟物，用于干细胞生物学和再生医学。