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Mechanism of CD33 receptor signaling in Alzheimer disease

CD33受体信号传导在阿尔茨海默病中的机制

基本信息

批准号：
10212834
负责人：
Tobias Sebastian Ulmer
金额：
$ 120.2万
依托单位：
UNIVERSITY OF SOUTHERN CALIFORNIA
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-05-15 至 2024-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10212834
关键词：
Adaptive Immune System Affinity Alzheimer&apos s Disease Alzheimer&apos s disease therapeutic Alzheimer&apos s disease therapy Amyloid beta-Protein Behavior Binding Binding Proteins Biochemical Biology CBL gene Cell Surface Receptors Cell physiology Cellular biology Crystallization Development Dimerization Disease Exhibits Family Genes Genomics Human Immersion Immune response Immunoglobulin Domain Immunoglobulins Immunologic Receptors Immunomodulators Individual Inflammatory Innate Immune Response Intervention Isotope Labeling Length Ligand Binding Ligand Binding Domain Ligands Link Membrane Microglia NMR Spectroscopy Neuraxis Neurodegenerative Disorders Pathogenesis Phagocytes Phagocytosis Pharmacology Phenotype Phospholipids Point Mutation Polysaccharides Receptor Activation Receptor Signaling Research Resolution Sialic Acids Signal Transduction Site Structure Sum System Testing Therapeutic Translating Transmembrane Domain base beta amyloid pathology combat cytotoxic dimer experience extracellular genome wide association study inhibitor/antagonist insight interest macrophage novel receptor reconstitution response sialic acid binding Ig-like lectin

项目摘要

Project Summary Pursuant to my long-term research interest, understanding the transmembrane (TM) signaling of cell surface receptors, the present proposal aims to elucidate the signaling mechanism of CD33, a key immune modulator of amyloid-β (Aβ) peptide clearance by microglia. The response of microglia, the resident phagocytes of the central nervous system, to Aβ aggregates can be either phagocytotic and neuroprotective or inflammatory and cytotoxic. This influence makes the innate immune response a major determinant of Alzheimer disease (AD) pathogenesis. The activation state and phagocytosis capability of microglia correlate with signaling by the CD33 cell-surface receptor. CD33 inactivation promotes phagocytosis and mitigates Aβ pathology, identifying CD33 inhibition as a promising therapeutic AD avenue. CD33 belongs to the family of sialic acid-binding im- munoglobulin-like receptor (Siglecs) and consists of two extracellular immunoglobulin-like domains (IgV and IgC2), a single-pass transmembrane (TM) domain and a cytosolic (CS) domain. Here, we hypothesize that the IgV-IgC2-TM domain-domain orientations and couplings change upon ligand binding, which transmits a signal (structural change) to the CS domains. Aim 1 lays the structural and biochemical groundwork to test this hy- pothesis. It establishes expression systems to produce isotope-labeled, glycosylated domains, determines their structure, oligomerization state and membrane immersion by NMR spectroscopy. Aim 2 traces the structural changes upon ligand binding from IgV to the CS domain in full-length CD33 reconstituted in phospholipid bicelles to directly test our signaling hypothesis. Specifically, ligand-induced changes in structure, domain- domain orientations and couplings will be established using NMR. The CD33 activity state will be verified in cultured macrophages and structure-based point mutations will be examined to provide target sites for phar- macological CD33 inhibition. Aim 3 examines the link between the CS domain and downstream signaling. The binding motif and affinity of established CD33-binding proteins will be determined by ITC and NMR. This or- ganizes the binding hierarchy of cytosolic ligands, identifies binders whose binding sequences overlap with se- quences that experience structural perturbations upon receptor activation, and identifies additional CD33 can- didate sequences for pharmacological intervention. While fragments of cell surface receptors with extracellular ligand-binding domains have been studied at atomic resolution, the relatively small size of CD33 allows the first study of an entire such receptor in solution. Delineating its complete signaling mechanism at atomic resolution establishes a paradigm for receptor biology and provides novel insight into Siglec biology. The direct targeting of Aβ amyloid as AD therapy has been largely unsuccessful and we provide CD33 target sites verified by cell biology that can be translated to therapeutics to harness the great potential of optimizing the innate immune response to combat AD.

项目摘要根据我长期的研究兴趣，了解细胞表面的跨膜信号传导受体，本建议旨在阐明CD 33的信号转导机制，一个关键的免疫调节剂 β-淀粉样蛋白（Aβ）肽被小胶质细胞清除。小胶质细胞的反应，中枢神经系统，Aβ聚集体可以是吞噬性和神经保护性的，也可以是炎症性的，细胞毒性。这种影响使得先天免疫反应成为阿尔茨海默病（AD）的主要决定因素发病机制小胶质细胞的活化状态和吞噬能力与通过微球介导的信号传导相关。 CD 33细胞表面受体。CD 33失活促进吞噬作用并减轻Aβ病理， CD 33抑制作为一种有前途的治疗AD的途径。CD 33属于唾液酸结合蛋白家族，免疫球蛋白样受体（Siglecs）并且由两个细胞外免疫球蛋白样结构域（IgV和IgV）组成。 IgC 2）、单次跨膜（TM）结构域和胞质（CS）结构域。在这里，我们假设， IgV-IgC 2-TM结构域-结构域取向和偶联在配体结合后改变，其传递信号（结构变化）到CS结构域。目的1为测试这种高分子奠定了结构和生化基础。假设它建立了表达系统，以产生同位素标记的糖基化结构域，结构、低聚状态和膜浸渍。目标2跟踪结构 IgV与重组于磷脂中的全长CD 33中CS结构域的配体结合后的变化 bicelles直接测试我们的信号假说。特别是，配体诱导的结构，结构域- 将使用NMR建立畴取向和耦合。CD 33活性状态将在将检查培养的巨噬细胞和基于结构的点突变，以提供PHAR的靶位点，宏观CD 33抑制。目标3检查CS域和下游信令之间的链路。的将通过ITC和NMR确定已建立的CD 33结合蛋白的结合基序和亲和力。这个还是- 组织胞质配体的结合层次，鉴定其结合序列与se- 在受体活化后经历结构扰动并鉴定额外的CD 33的序列可以- 用于药物干预的didate序列。而细胞表面受体片段与细胞外配体结合结构域已经在原子分辨率下进行了研究，CD 33的相对小的尺寸允许第一个对溶液中整个这种受体的研究。以原子分辨率描绘其完整的信号机制建立了受体生物学的范式，并为Siglec生物学提供了新的见解。直接攻击目标 Aβ淀粉样蛋白作为AD治疗在很大程度上是不成功的，我们提供了CD 33靶点，通过细胞验证，生物学可以转化为治疗方法，以利用优化先天免疫的巨大潜力，应对AD的挑战。