NRAMP1 AND PHAGOCYTE FUNCTION

描述(改编自申请人的摘要)：传染病 是北美的一个主要健康问题，部分原因是广泛存在的 抗生素抗药性病原体的出现。结核病是一种 这种反复出现的威胁的戏剧性例子，出现了高度 强毒和耐多药结核分枝杆菌(MTB)，以及增加的 艾滋病患者中结核病的流行情况。寄主防御机制研究进展 感染细胞内寄生虫，如分枝杆菌，以及 细菌在宿主中长期生存和复制的策略 吞噬细胞仍然知之甚少。更好地了解主持人 针对这种感染的防御机制可能会提出新的战略 对这些疾病的干预。用遗传学的方法研究自然界 人类分枝杆菌小鼠模型的耐药性和敏感性特征 感染，申请人已经确定了一个新的成分 吞噬细胞的抗微生物防御。在小鼠体内，复制 分枝杆菌和其他人类细胞内病原体，包括沙门氏菌， 利什曼病和布鲁氏菌是由卡介苗基因控制的。校长 研究人员克隆了卡介苗，并表明它编码一种吞噬细胞特异性 膜蛋白(Nramp1)，具有已知的结构特征 离子转运体和通道。Nramp1被招募到细胞的膜上 吞噬后不久，首席调查员已经 提出Nramp1底物对吞噬体内微生物的影响 复制。目前的提案有四个主要目标。第一个是 确定Nramp1基因和蛋白对宿主防御是否重要 预防感染结核杆菌。为此，在体内丢失Nramp1的影响 结核分枝杆菌在网状内皮器中复制的研究 死亡率，将进行评估。第二个目标是描述影响的特征 Nramp1与分枝杆菌吞噬小体的相关性 该细胞器的生化/生理特性及其对存活的影响 该地点的分枝杆菌和沙门氏菌。第三个目标是确定 Nramp1的转运机制和底物。第四个目标是 为了评估吞噬细胞特异性的功能同源性程度 Nramp1蛋白和广泛表达的Nramp2蛋白。一起， 这些研究应阐明Nramp1在心脏疾病中的作用机制 吞噬细胞的抗微生物防御，这反过来可能表明新的 针对结核病和其他传染病的干预措施。

DESCRIPTION (Adapted from the applicant's abstract): Infectious diseases are a major health problem in North America, in part due to the widespread emergence of antibiotic-resistant pathogens. Tuberculosis (TB) is a dramatic example of this recurring threat, with the appearance of highly virulent and multidrug resistant M. tuberculosis(MTB), and the increased prevalence of TB in AIDS patients. The mechanisms of host defense against infection with intracellular parasites such as mycobacteria, and the bacterial strategies underlying long-term survival and replication in host phagocytes remain poorly understood. A better understanding of the host mechanisms of defense against such infections may suggest new strategies for intervention in these diseases. Using a genetic approach to study natural resistance and susceptibility traits in mouse models of human mycobacterial infections, the applicant has identified a new component of the antimicrobial defenses of phagocytes. In the mouse, replication of mycobacteria and other human intracellular pathogens including Salmonella, Leishmania, and Brucella, is controlled by the Bcg locus. The principal investigator cloned Bcg and showed that it encodes a phagocyte specific membrane protein (Nramp1) that shares structural characteristics of known ion transporters and channels. Nramp1 is recruited to the membrane of the phagosome soon after phagocytosis, and the principal investigator has proposed that the substrate of Nramp1 affects intraphagosomal microbial replication. The current proposal has four main goals. The first is to determine if the Nramp1 gene and protein are important for host defense against infection with MTB. For this, the effect of loss of Nramp1 in vivo on replication of MTB in reticuloendothelial organs and on overall mortality, will be evaluated. The second goal is to characterize the effect of Nramp1 association with the mycobacterial phagosome on the biochemical/physiological properties of this organelle, and on the survival of mycobacteria and Salmonella at that site. The third goal is to identify the mechanism of transport and the substrate of Nramp1. The fourth goal is to evaluate the extent of functional homology between the phagocyte-specific Nramp1 protein and the ubiquitously expressed Nramp2 protein. Together, these studies should clarify the mechanism of action of Nramp1 in the antimicrobial defenses of the phagocyte, which may in turn suggest new interventions against TB and other infectious diseases.