LC3-Associated Phagocytosis

描述（由申请人提供）：两个古老的过程，吞噬作用和巨自噬，作为满足细胞能量需求的方式出现。两者都演变成宿主防御机制。在此资助的前一个支持期间，我们发现了一个过程，我们称之为“LC 3相关的吞噬作用”（LC 3-Associated Phagocytosis）。在这个过程中，吞噬细胞吞噬颗粒时产生的信号诱导自噬机制的组分与吞噬体结合，促进其与溶酶体融合（吞噬体成熟）。虽然吞噬乳胶珠（例如）不会诱导吞噬，但与TLR 1/2、TLR 2/6、TLR 4、FcR或吞噬垂死细胞的受体结合的颗粒会导致LC 3（ATG 8）募集到吞噬体膜。与大自噬一样，这种LC 3关联依赖于Beclin 1、PI 3 P生成、ATG 5和ATG 7，但与自噬不同的是，LC 3与单吞噬体膜（而不是自噬体的双膜）相关联。此外，与大自噬不同，自噬在自噬前起始复合物ULK 1、ATG 13和FIP 200的元件不存在的情况下进行。这提出了一个有趣的可能性：现在已经确定，自噬机制某些组分的缺陷会促进炎症性疾病，并损害宿主对细胞内感染的防御。作为一种离散现象的存在表明，至少有一些这样的影响可能具体涉及到生物多样性。在这里，我们提出的特点，它的关系吞噬体成熟，其在先天免疫反应和正常的稳态的作用。本申请所基于的我们的中心假设是，取决于伴随吞噬作用的信号传导，可以参与促进吞噬体货物分选到细胞内隔室以进行进一步的信号检测、处理或降解。具体来说，我们将问：1。自噬与巨自噬的启动有什么区别？在这里，我们将探讨启动和传播的分子事件，并评估这些如何不同于传统的大自噬。2.α-淀粉酶如何促进吞噬体成熟？在这里，我们将调查的组成部分，大大加快吞噬体成熟和点，在每个途径中，这种增强发生。我们将进一步研究LAP诱导的吞噬体成熟对巨噬细胞介导的宿主防御的影响。3.前列腺素如何影响炎症和体内平衡？在这里，我们将使用在体外和体内系统来询问的作用，在炎症反应中的死亡细胞，在体外和体内。虽然凋亡细胞被认为是“免疫沉默”，我们的证据表明，这可能是，至少部分是由于抑制炎症细胞因子反应的吞噬细胞。我们将测试这一令人兴奋的想法，并探索巨噬细胞和其他隔室中有缺陷的炎症的长期后果。总的来说，我们的项目旨在描述作为两个古老途径的结合点的免疫系统如何影响先天免疫，为理解炎症性疾病提供新的途径。

DESCRIPTION (provided by applicant): Two ancient processes, phagocytosis and macroautophagy, arose as ways to meet the energy demands of the cell. Both also evolved into mechanisms of host defense. During the previous support period for this grant, we discovered a process we term "LC3-Associated Phagocytosis" (LAP). In this process, signals that are generated upon engulfment of particles by phagocytic cells induce components of the autophagy machinery to associate with the phagosome, promoting its fusion to lysosomes (phagosome maturation). While engulfment of latex beads (for example) does not induce LAP, particles that engage TLR1/2, TLR2/6, TLR4, FcR, or receptors for engulfment of dying cells, cause recruitment of LC3 (ATG8) to the phagosome membrane. Like macroautophagy, this LC3 association depends on Beclin1, PI3P generation, ATG5, and ATG7, but unlike autophagy, LC3 associates with the single phagosome membrane (rather then the double membrane of autophagosomes). Further, unlike macroautophagy, LAP proceeds in the absence of elements of the autophagic pre-initiation complex, ULK1, ATG13, and FIP200. This raises an intriguing possibility: It is now well established that defects in some components of the autophagy machinery promote inflammatory disease and compromise host defense to intracellular infections. The existence of LAP as a discrete phenomenon suggests that at least some such effects may specifically relate to LAP. Here, we propose to characterize LAP, its relationship to phagosome maturation, and its roles in innate immune responses and normal homeostasis. Our central hypothesis, upon which this application is based, is that depending on signaling that accompany phagocytosis, LAP can be engaged to promote the sorting of the phagosome cargo to intracellular compartments for further signal detection, processing, or degradation. Specifically, we will ask: 1. What distinguishes the initiation of LAP versus macro-autophagy? Here we will explore the molecular events that initiate and propagate LAP and evaluate how these differ from those of conventional macroautophagy. 2. How does LAP promote phagosome maturation? Here we will investigate how the components of LAP greatly accelerate phagosome maturation and the points in each pathway where this enhancement occurs. We will further examine the consequences of LAP-induced phagosome maturation for macrophage-mediated host defense. 3. How does LAP impact on inflammation and homeostasis? Here we will use in vitro and in vivo systems to interrogate the roles of LAP in the inflammatory response to dying cells, in vitro and in vivo. While apoptotic cells are thought to be "immunologically silent" our evidence suggests that this may be, at least in part, due to suppression of the inflammatory cytokine response by LAP in phagocytes. We will test this exciting idea, and explore the long-term inflammatory consequences of defective LAP in macrophages and other compartments. Overall, our project seeks to characterize how LAP, as the conjunction of two ancient pathways, impacts innate immunity, offering new avenues for understanding inflammatory disease.