Pathways of Antigen Presentation by CD1

CD1 呈递抗原的途径

• 批准号: 8486245
• 负责人: Michael B. Brenner
• 金额: $ 38.43万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-12-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8486245
• 关键词: Antigen Presentation; Antigen Presentation Pathway; Antigen-Presenting Cells; Antigens; Arl proteins; Binding; Biological Assay; Biology; CD1 Antigens; CD1b antigen; CD1d antigen; CHS protein; Cell Maturation; Cell surface; Cells; Complex; Confocal Microscopy; Custom; Cytoskeleton; Cytosol; Dendritic Cells; Destinations; Dominant-Negative Mutation; Early Endosome; Endosomes; Family; Glutathione S-Transferase; Histocompatibility Antigens Class I; Histocompatibility Antigens Class II; Hybrids; Immune response; Infection; Libraries; Lipid Binding; Lipids; Location; Lysosomes; MHC Class I Genes; MHC Class II Genes; Mediating; Mediator of activation protein; Microbe; Molecular; Monomeric GTP-Binding Proteins; Organism; Peptides; Phagosomes; Process; Protein Binding; Protein Isoforms; Proteins; Recycling; Role; Simulate; Surface; Surface Antigens; T-Cell Activation; T-Lymphocyte; Time; Transmission Electron Microscopy; Travel; Vaccines; Vesicle; Work; Yeasts; adaptive immunity; antigen binding; cell killing; insight; killings; late endosome; member; microbial; microorganism antigen; mutant; novel; public health relevance; small hairpin RNA; trafficking

DESCRIPTION (provided by applicant): T cells recognize antigens only when bound by antigen presenting molecules. Peptides generated in the cytosol are transported into the ER where they bind MHC class I molecules, while MHC class II molecules are directed to endocytic compartments were they bind peptides. Thus antigen-binding is essentially determined by the differential trafficking and loading compartments of MHC class I and II molecules. Now, it is recognized that lipid antigens also can be recognized by T cells when presented by CD1 molecules. Like MHC molecules, trafficking determines where each of the CD1 isoforms binds antigens. CD1a traffics mainly through early endosomes and the early recycling compartment, while CD1b and CD1d traffic instead to late endosomes and lysosomes. Antigen binding occurs when CD1 molecules and lipid antigens intersect in these endosomal compartments. Since CD1 molecules bind lipid antigens in distinct endocytic compartments, they must then recycle or travel outbound to the cells surface. We and others have defined many of the key features of CD1 assembly in the ER, delivery to the cell surface and then internalization to localize in endosomes where lipid antigens are bound. Here, we developed a custom shRNA "trafficking" library and applied it in a screen to identify molecular mediators of CD1d recycling through lysosomes that is essential to deliver these molecules from the endosome compartments where they bind antigens to the cell surface where they can be recognized by T cells. We found, for the first time, that novel members of the Ras family of small GTPases, called Arl proteins, in particular Arl8, are essential regulators of lysosomal trafficking that is important in antigen presentation and phago-lysosome fusion. First, we will examine how lysosomal trafficking is blocked resulting in lysosome clustering in Arl8b shRNA knockdown or dominant- negative mutant expressing cells (Aim 1). Then, we will determine the role of Arl8b in the trafficking and presentation of antigens by CD1b and CD1d molecules that must traffic to lysosomes to acquire their lipid antigens and then deliver them to the cell surface for recognition (Aim 2). Beyond these CD1 antigen presenting molecules, MHC class II molecules also must traffic to and acquire antigens in lysosomes before delivering them to the cells surface. We will determine how Arl8b blocks MHC class II antigen presentation and their trafficking to the surface in the physiologically important process of dendritic cell maturation (Aim 3). We will then examine the role of Arl8b in the lysosomal trafficking necessary for delivery of its content to phagosomes in phago-lysosome fusion (Aim 4). Finally, we will identify molecules that bind Arl8b (Arl8 effectors) that enable it to mediate lysosomal trafficking through linkage to tethers, Rabs and the microtubular cytoskeleton (Aim 5). These studies will provide new insights into the biology of lysosomal trafficking and reveal how it impacts antigen-presenting molecules and other lysosomal contents that travel out from their endocytic locations to reach critical destinations at the cell surface (for T cell recognition) or to phagosomes (for microbial killing). PUBLIC HEALTH RELEVANCE: Antigen presentation by CD1 and MHC molecules is responsible for eliciting adaptive immunity. Here we determine how CD1 and MHC molecules that have bound microbial antigens are able to travel to the cell surface of antigen presenting cells to simulate T lymphocyte immune responses. Understanding how this pathway of antigen presentation works will make it possible to optimize it to generate effective vaccines for a wide variety of microbial infections. Further, we determine what regulates the process of how cells kill microbes by fusing the vesicles containing the organisms with vesicles that contain factors that can destroy the infections agents.

描述（由申请人提供）：仅当通过抗原呈现分子结合时，T细胞才能识别抗原。在细胞质中产生的肽被转运到ER中结合MHC I类分子的ER，而MHC II类分子被指示为内吞区室，如果它们结合肽。因此，抗原结合基本上是由MHC I类和II类分子的差分运输和加载室确定的。现在，人们认识到，当通过CD1分子呈现时，T细胞也可以识别脂质抗原。像MHC分子一样，运输决定了每种CD1同工型在何处结合抗原。 CD1A运输主要通过早期内体和早期回收室，而CD1B和CD1D流量转换为晚期内体和溶酶体。当这些内体室中的CD1分子和脂质抗原相交时，发生抗原结合。由于CD1分子在不同的内吞区室中结合脂质抗原，因此它们必须回收或出站前至细胞表面。我们和其他人已经定义了CD1组件在ER中的许多关键特征，传递到细胞表面，然后内部化以定位于脂质抗原被结合的内体。 在这里，我们开发了一个自定义的shRNA“运输”文库，并将其应用于屏幕上，以鉴定CD1D回收的分子介质通过溶酶体的分子介质，这对于从内体隔室中输送这些分子至关重要，在这些分子中，它们结合抗原与细胞表面结合到可以被T细胞识别的细胞表面。我们首次发现，小型GTPases的RAS家族的新成员称为ARL蛋白，特别是ARL8，是溶酶体运输的必要调节剂，在抗原表现和phogo-Lysosoms体融合中很重要。首先，我们将研究如何阻塞溶酶体运输，从而导致ARL8B shRNA敲低或显性 - 阴性突变体表达细胞的溶酶体聚类（AIM 1）。然后，我们将确定ARL8B在CD1B和CD1D分子对抗原的运输和呈现中的作用，这些分子必须传播到溶酶体以获取其脂质抗原，然后将其传递到细胞表面以识别（AIM 2）。除了这些CD1抗原呈现分子之外，MHC II类分子还必须在将其传递到细胞表面之前，还必须在溶酶体中访问并获取抗原。我们将确定ARL8B如何阻止MHC II类抗原表现及其在树突状细胞成熟的生理重要过程中运输到表面（AIM 3）。然后，我们将研究ARL8B在将其含量交付给Phago Lysosos体融合中所需的溶酶体运输中的作用（AIM 4）。最后，我们将确定结合ARL8B（ARL8效应子）的分子，从而使其能够通过与Tethers，Rabs和微管细胞骨架的连接来介导溶酶体运输（AIM 5）。 这些研究将为溶酶体运输的生物学提供新的见解，并揭示其如何影响抗原呈现的分子和其他从其内吞位置出现的溶酶体含量，从而到达内吞位置以到达细胞表面的关键目的地（用于T细胞识别）或对phagosomes（用于小动物杀死）。 公共卫生相关性：CD1和MHC分子的抗原呈现负责引起适应性免疫。在这里，我们确定具有结合微生物抗原的CD1和MHC分子如何能够传播到抗原呈递细胞的细胞表面以模拟T淋巴细胞免疫反应。了解这种抗原演示的途径如何工作将使它优化以生成各种微生物感染的有效疫苗。此外，我们通过将含有生物体的囊泡与包含可能破坏感染剂的因子的囊泡融合来调节细胞如何杀死微生物的过程。