Recognition and phagocytosis of bacteria in Drosophila

描述(申请人提供)：在先天性免疫中，病原体相关分子模式(PAMP)由模式识别受体(PRR)识别，模式识别受体(PRR)激活信号级联和效应器机制，如吞噬作用，将微生物清除出宿主系统。我们对果蝇中细菌的吞噬作用很感兴趣，因为对果蝇的细胞免疫知之甚少，这可能是一线免疫反应。在一项初步的基因筛查中，我们已经确定了8个突变，它们影响体内大肠杆菌(革兰氏菌)和/或金黄色葡萄球菌(革兰氏+菌)的吞噬作用。本研究的具体目的是：1.阐明两种催化性肽聚糖识别蛋白(PGRP-SC1a/b和PGRP-SC2)在细菌吞噬和激活抗菌肽(AMP)反应中的作用。我们的两个吞噬突变会影响PGRP-SC1a/b和PGRP-SC2的表达。我们将研究这些突变体如何影响吞噬作用和AMP反应。2.确定果蝇的免疫反应是否需要破坏革兰氏阴性细菌的外膜，以识别和清除细菌。我们认为，这可能是因为细胞壁上的肽聚糖可以触发下游的AMP反应。3.研究对免疫反应或吞噬作用起重要作用的基因如何影响体内吞噬小体成熟。我们的初步数据表明，PGRP-SC2、Rab14和AMPs可能在吞噬小体成熟过程中起重要作用。通过这些实验，我们希望了解这些基因在体内识别和吞噬细菌过程中所起的作用。

DESCRIPTION (provided by applicant): In innate immunity, pathogen associated molecular patterns (PAMPs) are recognized by pattern recognition receptors (PRRs) that activate signaling cascades and effector mechanisms, like phagocytosis which act to clear the microbes out of the host's system. We are interested in the phagocytosis of bacteria in Drosophila because not much is know about cellular immunity in flies and it may be the first-line immune response. In a pilot genetic screen, we have identified 8 mutations that affect the phagocytosis of E. coli (a Gram- bacteria) and/or S. aureus (a Gram+ bacteria) in vivo. The specific aims of this proposal are: 1. To elucidate the role two catalytic peptidoglycan recognition proteins (PGRP-SC1a/b and PGRP-SC2) play in the phagocytosis of bacteria and the activation of the antimicrobial peptide (AMP) response. Two of our phagocytosis mutations affect PGRP-SC1a/b and PGRP-SC2 expression. We will examine how these mutants affect phagocytosis and AMP responses. 2. To determine if disruption of the outer membrane of Gram-negative bacteria is necessary for recognition and clearance of the bacteria by the Drosophila immune response. We believe that this may be occuring to allow access to peptidoglycan in the cell wall which can trigger the downstream AMP responses. 3. To examine how genes important for immune responses or phagocytosis affect phagosome maturation in vivo. We have preliminary data indicating that PGRP-SC2, Rab14 and AMPs may be important for phagosome maturation. With these experiments, we hope to understand the role these genes play in recognition and phagocytosis of bacteria in vivo.