Regulation of cPLA2 in macrophages during phagacytosis

项目1的重点是研究普遍存在的IVA组胞质磷脂酶A （cPLA2）的调控，cPLA2启动溶血磷脂、血小板活化因子和类二十烷等多种脂质第二信使的产生。cPLA2的靶向缺失表明，它在体内平衡（女性生殖、器官生长、肾脏功能）和炎症性疾病（关节炎、急性肺损伤、肺纤维化、支气管反应性）中起着重要作用，强调了脂质介质在调节细胞过程中的重要性。类二十烷酸的产生也在先天免疫中发挥作用，是巨噬细胞对微生物感染的早期反应，介导血管通透性和白细胞的迁移。cPLA2在巨噬细胞对酵母菌和病原体白色念珠菌和单核李斯特菌的非声速吞噬过程中被有效激活。本研究的目的是阐明在小鼠腹腔巨噬细胞中这些微生物吞噬过程中cPLA2激活和失活的机制。据推测，cPLA2(1)在响应参与特定模式识别受体的微生物成分时启动类二十烷酸的产生，(2)在确定对微生物感染的易感性方面发挥作用。也有假设认为，在吞噬过程中，cPLA2变得失活，从而限制了类二十烷酸的产生和炎症的程度。具体目的是：(1)探讨dectin-1和toll样受体在白色念珠菌和单核增生李斯特菌吞噬过程中介导cPLA2活化的作用；(2)研究cPLA2和5-脂氧合酶的易位，以及钙信号的作用；(3)研究cPLA2在激酶活化和磷酸化中的作用；(4)研究氧化剂对cPLA2的失活作用和半胱天冬酶的蛋白水解降解作用；(5)确定cPLA2在这些微生物感染易感性中的作用。该项目将提供cPLA2和类二十烷酸产生的调控机制的详细信息，以及它们在微生物感染的先天免疫中的作用。

The focus of Project 1 is to study the regulation of the ubiquitous Group IVA cytosolic phospholipase A (cPLA2), which initiates the production of numerous lipid second messengers such as lysophospholipids, platelet activating factor and eicosanoids. Targeted deletion of cPLA2 has shown that it plays a fundamental role in homeostasis (female reproduction, organ growth, kidney function) and inflammatory diseases (arthritis, acute lung injury, pulmonary fibrosis, bronchial reactivity), emphasizing the importance of lipid mediators in regulating cell processes. Production of eicosanoids also plays a role in innate immunity and is an early response of macrophages to microbial infection, mediating vascular permeability and emigration of leukocytes. cPLA2 is potently activated in macrophages during non-opsonic phagocytosis of zymosan and the pathogens, Candida albicans and Listeria monocy to genes. The objectives of this proposal are to elucidate the mechanisms of cPLA2 activation and inactivation during phagocytosis of these microorganisms in resident mouse peritoneal macrophages. It is hypothesized that cPLA2 (1) initiates eicosanoid production in response to microbial components that engage specific pattern recognition receptors, and (2) plays a role in determining the susceptibility to microbial infection. It is also hypothesized that during the course of phagocytosis, cPLA2 becomes inactivated, which limits eicosanoid production and the extent of inflammation. The specific aims are: (1) to investigate the role of dectin-1 and Toll-like receptors in mediating cPLA2 activation during phagocytosis of Candida albicans and Listeria monocytogenes; (2) to study the translocation of cPLA2 and 5-lipoxygenase, and the role of calcium signals; (3) to study the role of kinase activation and phosphorylation of cPLA2; (4) to study cPLA2 inactivation by oxidants and proteolytic degradation by caspases; and (5) to determine the role of cPLA2 in susceptibility to infection by these microorganisms. This project will provide detailed information about mechanisms regulating cPLA2 and production of eicosanoids, and their role in innate immunity to microbial infection.