LC3-Associated Phagocytosis

摘要 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法而出现。 cell.两者都演变成宿主防御机制。在上一次资助期间，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， 在吞噬细胞吞噬颗粒时产生的自噬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）。在吞噬的同时 乳胶珠粒的量（例如）不会诱导结合TLR 1/2、TLR 2/6、TLR 4、FcR或 吞噬垂死细胞的受体，引起LC 3（ATG 8）募集到吞噬体膜。像 巨自噬，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，LC 3与单吞噬体膜（而不是双膜） 自噬体）。此外，与巨自噬不同，巨噬细胞在缺乏巨噬细胞因子的情况下进行。 自噬前起始复合物、ULK 1、ATG 13和FIP 200。这就提出了一个有趣的可能性： 自噬机制某些成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， 这表明，至少有一些这样的影响可能具体地涉及到电子束。在这里，我们建议描述 它与吞噬体成熟的关系，以及它在先天免疫反应和正常免疫反应中的作用。 体内平衡本申请所基于的我们的中心假设是， 伴随着吞噬作用，噬菌体可以参与促进吞噬体货物的分选到细胞内 用于进一步信号检测、处理或降解的隔室。具体来说，我们将问：1。什么 区分了巨噬细胞和巨噬细胞的启动？在这里，我们将探讨分子事件 启动和传播巨噬细胞，并评估它们与传统的巨噬细胞有何不同。2. α-淀粉酶如何促进吞噬体成熟？在这里，我们将研究如何组成的 大大加速吞噬体成熟和每个途径中发生这种增强的点。 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3.前列腺素如何影响炎症和体内平衡？在这里，我们将使用体外和 在体内系统中询问的作用，死亡细胞的炎症反应中，在体外和体内。 虽然凋亡细胞被认为是“免疫沉默”的，但我们的证据表明，这可能是，至少， 部分原因是由于巨噬细胞对炎性细胞因子反应的抑制。我们将测试这个 令人兴奋的想法，并探讨长期炎症后果的缺陷，巨噬细胞和 其他隔间。总的来说，我们的项目旨在描述两个古老的结合是如何形成的， 通路，影响先天免疫，为理解炎症性疾病提供了新的途径。

Abstract 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.