Phagocytosis in Pulmonary Alveolar Macrophages

肺泡巨噬细胞的吞噬作用

• 批准号: 7088897
• 负责人: STEVEN M GREENBERG
• 金额: $ 38.27万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-02-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7088897
• 关键词: RNA interference; actin binding protein; actins; alveolar macrophages; antibody receptor; biological signal transduction; bone marrow; computer program /software; cytoskeleton; dynamin; enzyme substrate; genetically modified animals; immunoglobulin G; laboratory mouse; phagocytosis; phosphorylation; protein protein interaction; protein structure function; protein tyrosine kinase; proteomics; small interfering RNA; tissue /cell culture

DESCRIPTION (provided by applicant): Phagocytosis is a phylogenetically ancient response to particulate stimuli adapted by specialized cells of the immune system. Among the best characterized phagocytic receptors are those that recognize the Fc portion of IgG (FCyRs). Phagocytosis via FCyRs requires the recruitment and activation of Syk, a tyrosine kinase expressed predominantly in hematopoietic cells. In this proposal we outline approaches to identify and characterize downstream targets of Syk that initiate or modify phagocytic signaling. Using proteomics to probe the "phosphotyrosome" of phagocytosis, we have identified proteins that either undergo enhanced tyrosine phosphorylation, or associate with phosphotyrosyl-containing proteins, during phagocytosis. Among these proteins are moesin, a member of the ERM family of actin-binding proteins and Abpl, an adaptor for F-actin, and dynamin. We hypothesize that moesin and ezrin, 2 ERM family members, stabilize the association of the actin based cytoskeleton with the plasma membrane in nascent pseudopods, thereby contributing to pseudopod rigidity. As both proteins contain functional immunoreceptor tyrosine-based activation motifs (ITAMs) that potentially bind Syk, they may act as direct transducers of the phagocytic signal. In Specific Aim I, we outline approaches to test this hypothesis. These experiments include use of software we helped design to predict effective siRNA sequences. In Specific Aim II, we will determine whether Abpl and/or its family members, cortactin and HS1, coordinate the delivery of cytoskeletal components with endo-/exocytic machinery (dynamin). As we have previously proposed a "two compartment" model of phagocytosis whereby the programs of cytoskeletal assembly and membrane trafficking both contribute to phagocytosis, Abp1 and its homologs would fulfill the role of molecular coordinator of these events.

描述（由申请人提供）：吞噬作用是一种系统发育上古老的对免疫系统特殊细胞适应的颗粒刺激的反应。特征最明确的吞噬细胞受体是那些识别 IgG Fc 部分 (FCyR) 的吞噬细胞受体。 FCyR 的吞噬作用需要招募和激活 Syk，这是一种主要在造血细胞中表达的酪氨酸激酶。在本提案中，我们概述了识别和表征 Syk 启动或修改吞噬信号传导的下游靶点的方法。使用蛋白质组学来探测吞噬作用的“磷酸酪氨酸体”，我们已经鉴定出在吞噬过程中经历增强的酪氨酸磷酸化或与含磷酸酪氨酰的蛋白质相关的蛋白质。这些蛋白质包括 Moesin（肌动蛋白结合蛋白 ERM 家族的成员）和 Abpl（F-肌动蛋白和动力蛋白的接头）。我们假设，Moesin 和 ezrin（2 个 ERM 家族成员）稳定了新生伪足中基于肌动蛋白的细胞骨架与质膜的结合，从而有助于伪足刚性。由于这两种蛋白都含有可能结合 Syk 的功能性免疫受体酪氨酸激活基序 (ITAM)，因此它们可能充当吞噬信号的直接转导器。在具体目标一中，我们概述了检验这一假设的方法。这些实验包括使用我们帮助设计的软件来预测有效的 siRNA 序列。在特定目标 II 中，我们将确定 Abpl 和/或其家族成员 Cortactin 和 HS1 是否与内/胞吐机制（动力）协调细胞骨架成分的递送。正如我们之前提出的吞噬作用的“两室”模型，其中细胞骨架组装和膜运输程序都有助于吞噬作用，Abp1 及其同源物将履行这些事件的分子协调员的作用。