Role of Rab27 in Granulocyte Function

摘要 中性粒细胞含有四种类型的分泌细胞器，它们含有对细胞增殖和分化至关重要的专门蛋白质。 它们的杀菌活性。其颗粒中有毒物质的无限制释放将是 对宿主有害。这些颗粒的胞吐作用是分层次和差异调节的。 这与货物蛋白在粘附，迁移， 趋化性、吞噬作用和活性氧的产生。囊泡机制 对中性粒细胞的胞吐作用知之甚少。Rab 27 a是一个小的GTdR， 分泌过程其在粒细胞中的作用尚不清楚。Rab 27 a的遗传缺陷 与人类免疫缺陷Griscelli综合征相关，其中中性粒细胞功能 可以改变。根据我们实验室的大量证据，我们提出 以下假设：1）Rab 27 a及其效应子JFC 1和Munc 13 -4在 嗜中性粒细胞的胞吐作用和依赖于颗粒蛋白的相关功能 动员; 2）涉及货物释放到周围环境中的颗粒是分子 并且在机制上不同于参与货物释放到吞噬体中的那些; 3）JFC 1 提供了将含有Rab 27 a的囊泡靶向至位于靶向区的对接位点所需的特异性。 Munc 13 -4调节融合过程。到 了解Rab 27 a依赖性粒细胞囊泡运输的机制，我们 提出三个具体目标：1）研究Rab 27 a在胞吐中的作用， 使用Rab 27 a缺陷小鼠，在粒细胞中的吞噬作用; 2）为了鉴定 通过电子调节粒细胞中含有Rab 27 a的囊泡的对接， 使用JFC 1缺陷型细胞的渐逝荧光显微术; 3）为了鉴定细胞和 由Rab 27 a效应子Munc 13 -4调节的生化事件。我们计划阐明 使用来自Munc 13 -4缺陷的中性粒细胞的囊泡融合和胞吐作用的潜在机制 小鼠拟议的研究计划的结果应该揭示的分子机制 囊泡对接，融合和分泌的中性粒细胞，并导致有效的分子策略， 炎症性疾病的治疗。

ABSTRACT Neutrophils contain four types of secretory organelles that hold specialized proteins essential for their microbicidal activity. Unrestricted release of the toxic content of their granules would be injurious to the host. Exocytosis of these granules is hierarchical and differentially regulated. This correlates with the role the cargo proteins play in the processes of adhesion, migration, chemotaxis, phagocytosis and production of reactive oxygen species. The mechanism of vesicle exocytosis in neutrophils is poorly understood. Rab27a is a small GTPase associated with secretory processes. Its role in granulocytes is unknown. Genetic defects in Rab27a are associated with the human immunodeficiency Griscelli syndrome in which neutrophil function may be altered. On the basis of extensive evidence from our laboratory, we propose the following hypotheses: 1) Rab27a and its effectors JFC1 and Munc13-4 play a central role in exocytosis in neutrophils and in associated functions that depend on granular protein mobilization; 2) granules implicated in cargo release into the surrounding milieu are molecularly and mechanistically different from those involved in cargo release into the phagosome; 3) JFC1 provides the specificity required to target Rab27a-containing vesicles to the docking site at the plasma membrane during exocytosis while Munc13-4 regulates the fusion process. To understand the mechanisms of Rab27a-dependent vesicular trafficking in granulocytes, we propose three specific aims: 1) To examine the role that Rab27a plays in exocytosis and phagocytosis in granulocytes, using Rab27a-deficient mice; 2) To identify the mechanisms that regulate the docking of Rab27a-containing vesicles in granulocytes by electron and evanescence fluorescence microscopy using JFC1-deficient cells; 3) To identify the cellular and biochemical events regulated by the Rab27a-effector Munc13-4. We plan to elucidate the mechanism underlying vesicle fusion and exocytosis using neutrophils from Munc13-4-deficient mice. The results of the proposed research plan should uncover the molecular mechanisms of vesicle docking, fusion and secretion in neutrophils and lead to effective molecular strategies for the treatment of inflammatory diseases.