REGULATION OF HUMAN PHAGOCYTE FUNCTION BY RAC PROTEINS

描述(改编自调查者摘要)：人类吞噬细胞 白细胞在宿主对多种细菌的防御中起着重要作用 感染剂。一旦遇到微生物，它们就会经历 形态和功能的改变依赖于细胞骨架， 通常伴随着膜呼吸爆发活动， 引发有毒氧代谢产物的产生；这两个过程都是 受GTPase调控，RAC。调查人员发现了一部小说 趋化刺激激活的一类RAC效应蛋白 人类中性粒细胞，即p21激活的蛋白激酶(PAK)。近期 有证据表明，这些激酶在中性粒细胞中起着重要作用。 当它与免疫功能有关时，发出信号。 该项目将调查某些依赖RAC的中性粒细胞 通过阐明PAK的激活过程，反应是通过PAK介导的 更详细地通过鉴定中性粒细胞中的PAK目标蛋白。他们 将研究GTP酶通过突变激活PAK的机制 对rac1、rac2、cdc42和PAK本身的分析。使用提纯的成分， 完整的中性粒细胞和已建立的细胞系，上游信号的作用 除了活化的RAC/CDC42外，还将通过以下研究阐明 调节脂质第二信使和新的PAK结合蛋白。至 定义PAK如何介导细胞对RAC或CDC42的响应，他们将追求 下游效应器的识别。最初，他们的研究将 将重点放在作为PAK磷酸化靶标的NADPH氧化酶成分上 扩展以鉴定新的PAK激活或相互作用的中性粒细胞蛋白。 他们将对这些蛋白质进行生化表征，并评估它们的作用。 在PAK介导的信号通路中使用细胞途径。这些 研究应该能够使我们对RAC/PAK调节事件有进一步的了解 在宿主防御和炎症性疾病方面。

DESCRIPTION (Adapted from Investigator's abstract): Human phagocytic leukocytes play important roles in host defense against a variety of infectious agents. Upon encountering a microorganism, they undergo morphological and functional alterations dependent upon the cytoskeleton, and usually accompanied by membrane respiratory burst activity that initiates the generation of toxic oxygen metabolites; both processes are regulated by the GTPase, Rac. The investigators have identified a novel class of Rac effector proteins which are activated by chemotactic stimuli in human neutrophils, the p21-activated protein kinases (PAKs). Recent evidence indicates that these kinases play important roles in neutrophil signaling as it relates to immune functions. This project will investigate whether certain Rac-dependent neutrophil responses are mediated through PAK by elucidating the PAK activation process in more detail and by identifying PAK target proteins in neutrophils. They will investigate mechanisms of PAK activation by GTPases through mutational analysis of Rac1, Rac2, Cdc42 and PAK itself. Using purified components, intact neutrophils and established cell lines, the role of upstream signals in addition to activated Rac/Cdc42 will be elucidated through studies of regulatory lipid second messengers and of novel PAK binding proteins. To define how PAK mediated cellular responses to Rac or CdC42, they will pursue the identification of downstream effectors. Initially, their studies will focus on NADPH oxidase components as PAK phosphorylation targets and will be extended to identify novel PAK-activated or interacting neutrophil proteins. They will characterize these proteins biochemically and evaluate their role in PAK-mediated signalling pathways using cellular approaches. These studies should enable us to gain further insight in Rac/PAK regulated events in host defense and inflammatory diseases.