Studies on the Structure of Basement Membranes

COL4A3、COL4A4和COL4A5基因的数百个变异导致广泛的肾小球疾病 影响肾小球基底膜(GBM)功能。这些基因编码了 胶原IVGB345支架是α的主要成分，也是Goodppure的自身抗原。 自身免疫性疾病，该蛋白在Alport综合征和其他遗传性肾小球疾病中发生突变。全科医生 疾病已经并将继续成为解开人类基因组分子结构之谜的先锋。 α345支架和导致获得性和遗传性肾小球疾病的致病机制。我们的 最重要的假设是：IV型胶原α345支架连接大分子形成超分子 支架的复合体和扰动会导致肾小球疾病。四个具体目标解决关键问题 根据我们以前和最近的发现定义的未回答的问题。目标1：α345NC1 六角星。测定α345NC1六聚体的原子结构及GP表位的作用机制 队形。345NC1六聚体GP自身抗原的结构尚不清楚。我们假设在 非免疫原性345NC1六聚体、EA和EB区四级结构的扰动 发生构象变化，形成致病的GP新表位。目的2：α3苏黎世突变。至 确定α3苏黎世突变对GP表位形成的影响。我们在α3NC1中发现了一个突变 与第一例家族性GP病相关的区域，为触发 机制。我们假设该突变导致Ea和Eb区的结构扰动。 α3NC1，这可能有助于GP表位的呈递。目的3.氯化环类化合物。确定…的角色 氯离子参与了IV型胶原α345支架的组装和GP表位的形成。而结构， 我们对α121支架的组装和功能进行了40多年的成功研究 关于α345脚手架仍然鲜为人知。我们证明了氯浓度在GP中是一个关键因素 抗体结合。我们假设345NC1六聚体的组装，其稳定性和GP反应性为 依赖于氯离子。目的4：α121超分子络合物。为了表征超分子 基底膜内的α121IV型胶原复合体。我们发现了一种花环建筑 涂覆有蛋白多糖的α121支架。这种超结构是基底膜的一个潜在的核心特征。 我们假设IV型胶原α121支架连接大分子形成不同的超分子 使基底膜能够组装的复合体。这些目标的实现将产生新的见解。 到GP病的病因学和IV型胶原支架的结构和组装，导致一个框架 用于开发治疗GBM疾病的新策略。

Hundreds of variants in the COL4A3, COL4A4 and COL4A5 genes cause a broad range of glomerulopathies affecting the function of the glomerular basement membrane (GBM). These genes encode the assembly of collagen IV α345 scaffolds, the major constituent of the GBM, the autoantigen in Goodpasture’s (GP) autoimmune disease, and the protein mutated in Alport syndrome and other genetic glomerulopathies. GP disease has and continues to serve as the vanguard for unlocking mysteries of the molecular structure of the α345 scaffold and pathogenic mechanisms underlying both acquired and genetic glomerulopathies. Our overarching hypothesis is: Collagen IV α345 scaffold tethers macromolecules forming supramolecular complexes and perturbation of scaffold causes glomerulopathies. Four specific aims address key unanswered questions that are defined based on our previous and recent discoveries. Aim 1: α345NC1 Hexamer. To determine the atomic structure of the α345NC1 hexamer and mechanism of GP epitopes formation. The structure of the 345NC1 hexamer, GP autoantigen, is unknown. We hypothesize that upon perturbation of quaternary structure of the non-immunogenic 345NC1 hexamer, EA and EB regions undergo conformational changes forming pathogenic GP neoepitopes. Aim 2: α3 Zurich Mutation. To determine the impact of α3 Zurich mutation on GP epitopes formation. We found a mutation in α3NC1 domain associated with the first case of familial GP disease, providing genetic evidence for a triggering mechanism. We hypothesize that the mutation causes structural perturbation of the EA and EB regions of α3NC1, which can contribute to GP epitopes presentation. Aim 3. Chloride ring. To determine role of chloride in assembly of the collagen IV α345 scaffold and formation of GP epitopes. Whereas structure, assembly and functions of the α121 scaffold has been successfully studied for over 40 years, our knowledge about the α345 scaffold remains obscure. We demonstrated that chloride concentration is a critical factor in GP antibody binding. We hypothesize that assembly of the 345NC1 hexamer, its stability and GP-reactivity is dependent on chloride ions. Aim 4: α121 Supramolecular complexes. To characterize the supramolecular complexes of α121 collagen IV within a basement membrane. We discovered a garland architecture of the α121 scaffold coated with proteoglycans. This suprastructure is a potential core feature of basement membrane. We hypothesize that collagen IV α121 scaffold tethers macromolecules forming distinct supramolecular complexes which enable basement membrane assembly. The achievement of the aims will yield new insights to the etiology of GP disease and the structure and assembly of collagen IV scaffolds, leading to a framework for development of novel therapeutic strategies for GBM diseases.