PHOSPHOLIPASE-DEPENDENT SIGNALING IN PHAGOCYTOSIS

单核/巨噬细胞是花生四烯酸的主要细胞来源 （AA）。 这种脂肪酸具有相当大的生物重要性，因为它是 类花生酸炎症介质的前体。 虽然其 代谢是众所周知的，刺激AA的膜事件 释放不是。 AA释放磷脂酶（PL）的鉴定， 其响应于限定的膜事件而被激活， 对我们理解受体介导的信号转导 并具有潜在的治疗价值。 通过控制AA的释放， 这样的PL将提供用于调节蛋白质表达的强有力的调节位点。 炎症介质的水平。 PI描述了 一种独特的单核细胞PL，在抗体介导的 吞噬作用 这种吞噬性PL选择性地从 磷脂酰乙醇胺，显然是钙非依赖性和必要的 用于摄入IgG调理颗粒。 已经进行了体外测定， 研究这种酶的细胞生物学， 洁净. 具体而言，1）PL的特征在于： 就其分类为PLA 2或PLC而言，其调制方式为 基于机制的抑制剂及其细胞定位，2）酶 将通过液相等电聚焦和标准 生化技术，3）PL参与非吞噬事件，如 由于将评估毒性氧代谢物的粘附和产生， 4)细胞因子刺激和单核细胞成熟对PL的影响 5）Fc受体的组分- 调节PL活性的激活的信号级联将被 鉴定 吞噬型磷脂酶的特性及其在细胞内的表达 了解其调节机制将有助于我们理解信号 一般而言，AA的转导作用，更具体地说，AA作为一种 细胞内第二信使，并将增加我们对 炎症的分子机制。

Monocyte/macrophages are a major cellular source of arachidonic acid (AA). This fatty acid has considerable biological importance as it is the precursor of the eicosanoid inflammatory mediators. Although its metabolism is well understood, the membrane events which stimulate AA release are not. Identification of an AA-releasing phospholipase (PL), which is activated in response to a defined membrane event, would be invaluable to our understanding of receptor-mediated signal transduction and of potential therapeutic value. By controlling the release of AA, such a PL would provide a powerful regulatory site for modulation of the levels of inflammatory mediators in inflammation. The PI has described a unique monocytic PL which is activated during antibody-mediated phagocytosis. This phagocytic PL selectively releases AA from phosphatidyl-ethanolamine, is apparently Ca-independent and essential for ingestion of IgG-opsonized particles. An in vitro assay has been developed to study the cell biology of this enzyme and to follow its purification. Specifically, 1) the PL will be characterized with respect to its classification as a PLA2 or PLC, its modulation by mechanism-based inhibitors and its cellular localization, 2) the enzyme will be purified by fluid phase isoelectric focusing and standard biochemical techniques, 3) PL involvement in non-phagocytic events, such as adhesion and generation of toxic oxygen metabolites will be assessed, 4) the effect of cytokine stimulation and monocyte maturation on PL expression will be measured and 5) components of the Fc receptor- activated signalling cascade which regulate PL activity will be identified. Characterization of the phagocytic phospholipase and a knowledge of its regulation will advance our understanding of signal transduction in general and, more specifically, the role of AA as an intracellular second messenger and will increase our knowledge of the molecular mechanisms of inflammation.