Mechanisms of cross-presenting antigens in phagosomes on MHC I molecules to stimulate CD8 T lymphocyte responses

MHC I分子上的吞噬体中交叉呈递抗原刺激CD8 T淋巴细胞反应的机制

• 批准号: 9797712
• 负责人: KENNETH L ROCK
• 金额: $ 41.88万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-24 至 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9797712
• 关键词: AGFG1 gene; Abbreviations; Address; Antigen Presentation; Antigen Presentation Pathway; Antigen-Presenting Cells; Antigens; Back; Binding; Biological; CD8-Positive T-Lymphocytes; Cells; Cleaved cell; Complex; Cross Presentation; Cytosol; Data; Dendritic Cells; Development; Disease; Doxycycline; Environment; Face; Generations; Genetic; Goals; Grant; Health; Hybrids; I-antigen; Immune response; Immune system; Immunity; Immunologic Monitoring; Immunologic Surveillance; Immunotherapy; Ingestion; Knock-out; Lead; Link; Major Histocompatibility Complex; Malignant Neoplasms; Modeling; Monitor; Nucleoproteins; Oligopeptides; Ovalbumin; PA700 proteasome activator; Pathologic Processes; Pathway interactions; Patients; Peptide Transport; Peptides; Phagosomes; Physiological; Polyubiquitin; Process; Proteasome Binding; Proteins; Proteomics; Role; Subunit Vaccines; T cell response; Tertiary Protein Structure; Testing; Tissues; Ubiquitin; Vaccines; Vacuole; Viral; Virus; Virus Diseases; base; beta-2 Microglobulin; in vivo; insight; macrophage; multicatalytic endopeptidase complex; pathogen; peptide I; prevent; response; vaccine development; vaccine immunotherapy

Abstract In most cells the MHC I antigen presentation pathway exclusively displays peptides that are derived from a cell's own proteins. In contrast, dendritic cells (DCs) and macrophages (MØs) are capable of acquiring and then displaying peptides from external antigens through a process called cross presentation (XPT). XPT is the key mechanism that allows the immune system to recognize and then mobilize a CD8 T cell response to cancers, many viral infections and intracellular pathogens. Consequently, this pathway is important for immune surveillance and is an attractive target to enable vaccines to elicit CD8 T cell immunity, which is something current subunit vaccines fail to do. The overall goal of this grant is to elucidate key mechanisms that allow DCs to carry out this critical function. In the major XPT pathway, exogenous proteins are first internalized into phagosomes and then transferred into the cytosol, where they are cleaved into oligopeptides by proteasomes. Recent data suggests that the proteasome-generated peptides for XPT are subsequently imported back into phagosomes for binding to MHC I molecules (referred to here as “phagosomal XPT”). However, why such peptides would not simply be delivered to MHC I molecules in the ER, as most cytosolic generated peptides are, is a mystery and one that our first aim seeks to solve. Our underlying hypothesis, supported by preliminary data, is that a subset of proteasomes physically associates with the cytosolic face of phagosomes and does so by via their PA28 capping complex binding to the cytosolic domains of the peptide-loading complex (TAP+Tapasin). This arrangement thereby links local peptide generation (by the phagosome-bound proteasomes) to local peptide transport (by phagosomal TAP). The importance of these hypotheses is that they have the potential to fill in key missing links in the phagosomal XPT pathway and to identify an important function for PA28 complexes, which up until now have thought to be relatively unimportant. Our second aim seeks to elucidate mechanisms that allow MHC I molecules to bind peptides in the “unfriendly” environment of the phagosome and to address the question of why XPT of antigens is surprisingly much more efficient when the exogenous antigen is cell-associated, as compared to the same antigen in any other form. This aim will test the hypothesis that ß2 microblobulin (ß2M) from ingested exogenous cells promotes the formation of peptide-MHC I complexes in phagosomes. In this mechanism, free ß2M (from ingested cells) + free MHC I heavy chains delivered to and/or generated in phagosomes (from complexes denatured in the vacuole) + peptides (from PA28-proteasome-products that are imported into phagosomes by TAP) associate to form intraphagosomal MHC I-peptide complexes. The importance of this hypothesis is that it would provide insight into a biologically important process. Moreover, this mechanism may be able to be manipulated to enhance XPT for vaccines/immunotherapies.

抽象的 在大多数单元中 自己的蛋白质。相反，树突状细胞（DCS）和巨噬细胞（Møs）能够获取，然后 通过称为交叉表现（XPT）的过程从外部抗原显示肽。 XPT是关键 允许免疫系统识别然后动员CD8 T细胞响应的机制， 许多病毒感染和细胞内病原体。因此，该途径对于免疫很重要 监视，是使疫苗能够引起CD8 T细胞免疫的有吸引力的目标，这是 当前的亚基疫苗无法做到。这笔赠款的总体目标是阐明允许DC的关键机制 执行此关键功能。在主要的XPT途径中，首先将外源蛋白化为 吞噬体然后转移到细胞质中，在那里它们被蛋白酶体裂解成寡肽。 最近的数据表明，XPT的蛋白酶体生成的辣椒随后被进口回到 吞噬体与MHC I分子结合（此处称为“吞噬体XPT”）。但是，为什么这样 肽不会简单地递送到ER中的MHC I分子，因为大多数胞质产生的宠物是， 这是一个神秘的，我们的第一个目标试图解决。我们的基本假设，得到初步数据支持的， 是蛋白酶体的一个子集与吞噬体的胞质面物理相关，并通过通过 他们的PA28封端复合物结合到肽加载络合物的胞质结构域（Tap+tapasin）。 因此，这种布置将局部肽产生（通过吞噬体结合蛋白酶体）链接到局部肽 运输（通过吞噬小龙头）。这些假设的重要性是它们有可能填写密钥 缺少吞噬体XPT途径中的链接，并确定PA28复合物的重要功能，该功能 到目前为止，人们认为相对不重要。我们的第二个目标旨在阐明允许的机制 MHC I分子在吞噬体的“不友好”环境中结合辣椒并解决这个问题 为什么当外源抗原与细胞相关时，抗原XPT的效率更为有效， 与其他任何形式的相同抗原相比。该目标将检验以下假设：ß2微蛋白（ß2m） 从摄入的外源细胞中促进吞噬体中胡椒-MHC I配合物的形成。在这个 机构，Freeß2M（来自摄入的细胞） +传递到和/或生成的自由MHC I重链 吞噬体（来自真空中的复合物） +肽（来自Pa28-蛋白酶体产品， 由Tap）助理导入吞噬体中，形成了含糊膜的MHC I肽复合物。这 该假设的重要性是它将提供对生物学上重要过程的见解。而且，这 可以操纵机制以增强疫苗/免疫疗法的XPT。