Toll-like Receptor Control of MHC Class I Endocytosis

建议书摘要 交叉呈现是主要组织相容性复合体I类(MHC-I)分子 装载来自胞外蛋白质来源的多肽，包括内化的可溶性蛋白质， 微生物和垂死的细胞。交叉呈现是树突状细胞(DC)的特长，负责细胞类型 对于启动幼稚的T细胞，但即使在DC中，这种特性也可以是自然产生的，或者必须在激活后获得。 被称为cDc1的传统DC是强有力的交叉呈现者，可以结构性地这样做，同时具有煽动性 在炎症组织中发现的单核细胞来源的DC和另一种常规DC亚群cDC2也可以交叉 处于感染和炎症状态。与数据中心公认的异构性并行， 处于稳态和炎症状态的组织中，DC亚群在动态平衡或炎症过程中具有不同的功能状态 发炎。这种功能差异主要是通过先天信号受体的参与来协调的， 例如Toll样受体(TLRs)，它介导不同的细胞程序，包括转录 炎症基因和介质，以及亚细胞泡运输的快速重组 翻译后事件，如磷酸化。我们必须研究DC的全部光谱 当先天受体被激活时，在炎症下的功能，而不限于DC分类，如 具有僵硬、不灵活功能的子集。定义炎症性先天受体的性质和信号 使DC能够增强其交叉展示能力或重新获得它，将为疫苗设计提供信息 传染病和癌症，在这些疾病中，细胞毒性CD8 T细胞对生物体的生存是绝对必要的。一个 对交叉呈现规律的机械剖析对小说的识别具有重要意义 可用于利用CD8 T细胞免疫并提供长期保护的治疗靶点 未来感染或癌症复发。抗原内化、加工和递呈在很大程度上依赖于 亚细胞泡状流。为研究小鼠常规DC而开发的体外工具已被用作 负责交叉呈现机制及其调节的开创性发现的主力，这是 已经转化为人类DC亚群，并影响了疫苗设计和细胞治疗。这样的工具有 使我们能够发现MHC-I的内体回收隔室存储对于交叉呈现和 被免疫逃避病毒感染后耗尽，在人类DC中复制的发现。我们有 现在发现内吞抗原的交叉递呈与一种特定的先天受体之间的新联系 据报道，表达于培养的DC、炎症性DC和CDC2亚群。我们假设这个受体 使MHC-I交通与内吞抗原相交，以许可感染期间的交叉呈递。使用培养的和 从小鼠淋巴器官分离的体外树突状细胞，我们将定义不同的先天性免疫信号 调节MHC-I内吞作用的成分。我们将确定MHC-I的特性，使其能够调节 内吞作用。我们的研究将为防治传染病和癌症提供急需的T细胞疫苗。

PROPOSAL SUMMARY Cross-presentation is the process whereby major histocompatibility complex class I (MHC-I) molecules are loaded with peptides derived from an extracellular source of proteins including internalized soluble proteins, microorganisms and dying cells. Cross-presentation is a specialty of dendritic cells (DCs), cell types responsible for priming naïve T cells, but even in DCs, this specialty can come naturally or must be acquired upon activation. Conventional DCs known as cDC1 are potent cross-presenters and can do so constitutively, while inflammatory monocyte-derived DCs found in inflamed tissues and another subset of conventional DCs, cDC2, can also cross- present under conditions of infection and inflammation. Parallel to the well-established heterogeneity of DCs in tissues at steady state and inflammation, DC subsets have different functional states during homeostasis or inflammation. This functional difference is primarily orchestrated by the engagement of innate signaling receptors, such as Toll-like receptors (TLRs), that mediate diverse cellular programs including the transcription of inflammatory genes and mediators, as well as the rapid reorganization of subcellular vesicular traffic through post-translational events such as phosphorylation. It is imperative that we investigate the full spectrum of DC functions under inflammation when innate receptors are engaged, and to not be limited to DC classifications as subsets with rigid inflexible functions. Defining the nature of the inflammatory innate receptors and signals that enable DCs to augment their cross-presentation capacity or to acquire it anew, will inform vaccine design for infectious diseases and cancer where cytotoxic CD8 T cells are absolutely essential for organismal survival. A mechanistic dissection of the regulation of cross-presentation is important for the identification of novel therapeutic targets that can be exploited to harness CD8 T cell immunity and confer long term protection against future infection or cancer resurgence. Antigen internalization, processing, and presentation rely heavily on subcellular vesicular traffic. In vitro tools developed for studying murine conventional DCs have served as the workhorse responsible for seminal discoveries of the mechanisms of cross-presentation and its regulation, which have translated to human DC subsets and have impacted vaccine design and cellular therapies. Such tools have enabled our discovery of endosomal recycling compartment stores of MHC-I critical for cross-presentation and depleted upon infection by immunoevasive viruses, findings that have been replicated in human DCs. We have now discovered a new link between cross-presentation of endocytosed antigen and a particular innate receptor reported to be expressed by cultured DCs, inflammatory DCs and a cDC2 subset. We hypothesize this receptor intersects MHC-I traffic with endocytic antigen to license cross-presentation during infection. Using cultured and ex-vivo DCs isolated from the lymphoid organs of mice, we will define the distinct innate immune signaling components that regulate MHC-I endocytosis. We will determine the features of MHC-I that enable its regulated endocytosis. Our studies will inform urgently needed T cell vaccines against infectious diseases and cancer.