Elucidation of a Eukaryotic Chemorepulsion Mechanism

真核细胞从化学防护剂来源的定向移动似乎起到了 在发育和消退炎症方面发挥重要作用，但对真核生物知之甚少 化学物质以及它们如何引导细胞运动。Dictyostelius细胞对分泌物的化学排斥 一种名为APRA的蛋白质是一种可以结合生物化学和遗传学来解释化学排斥的模型。 利用可用的突变体和初步的遗传筛选，我们鉴定了APRA受体，鉴定了几个 APRA信号转导通路的组成部分，并发现APRA化学排斥涉及一种 从根本上不同于化学吸引的机制。 APRA预测了与人类分泌蛋白二肽基肽酶IV(DPPIV)的结构相似， 并且与DPPIV共享功能特性。我们发现DPPIV对人和小鼠都有化学抵抗力 发现G蛋白偶联受体PAR2介导DPPIV化学排斥，并发现 小分子PAR2激动剂作为中性粒细胞化学抵抗剂。初步研究表明，有 APRA和PAR2激动剂化学排斥机制有很大的相似之处。 急性呼吸窘迫综合征(ARDS)是一种无法治愈的疾病，涉及肺部损害。 导致中性粒细胞进入肺部。中性粒细胞进一步损害肺部，导致更多的中性粒细胞 进入正反馈循环，这导致每年约200,000名ARDS患者中约40%的人死亡 在美国。对可能的治疗方法的一个令人兴奋的见解是，当DPPIV或PAR2激动剂 在两种ARDS小鼠模型中，它们被吸入肺部，诱导中性粒细胞离开肺部。钥匙 将其应用于临床的障碍是我们需要知道PAR2激动剂的化学斥力是什么 其机制是预测潜在的药物相互作用和副作用。 为了深入了解中性粒细胞离开组织的基本机制和方法，我们 建议利用APRA和PAR2激动剂的力量来阐明其化学排斥机制 来领导这项工作。我们将严格测试新发现的网柄苔藓化学排斥途径 成分，并确定它们在通路中的作用位置。我们将完成Dictyostants的遗传 筛查以进一步了解化学斥力，然后使用这些信息指导对 在中性粒细胞中可能有类似的机制。在检测人类中性粒细胞的化学斥力时，我们观察到 中性粒细胞在男性和女性之间的显著差异，我们将描绘其程度和分子 这种差异背后的机制。总之，这项拟议的工作将阐明一种鲜为人知的 基本机制，阐明了先天性免疫系统中意想不到的性别差异，并帮助 阐明PAR2激动剂如何在临床上用于将过量的中性粒细胞从组织中排出， 对男性和女性的治疗可能不同。

The directed movement of eukaryotic cells away from a source of a chemorepellent appears to play a major role in development and the resolution of inflammation, but very little is known about eukaryotic chemorepellents and how they direct cell motility. Chemorepulsion of Dictyostelium cells from a secreted protein called AprA is a model where one can combine biochemistry and genetics to elucidate chemorepulsion. Using available mutants and a preliminary genetic screen, we identified the AprA receptor, identified several components of the AprA signal transduction pathway, and found that AprA chemorepulsion involves a fundamentally different mechanism from chemoattraction. AprA has predicted structural similarity to the human secreted protein dipeptidyl peptidase IV (DPPIV), and shares functional properties with DPPIV. We found that DPPIV is a chemorepellent for human and mouse neutrophils, found that the G protein-coupled receptor PAR2 mediates DPPIV chemorepulsion, and found that small molecule PAR2 agonists act as neutrophil chemorepellents. Preliminary studies indicate that there are strong similarities between the AprA and PAR2 agonist chemorepulsion mechanisms. Acute respiratory distress syndrome (ARDS) is an untreatable disease involving damage to the lungs causing neutrophils to enter the lungs. The neutrophils further damage the lungs, causing more neutrophil entry in a positive feedback loop, and this results in the death of ~40% of the ~200,000 ARDS patients per year in the US. An exciting insight into a possible therapeutic approach is that when DPPIV or PAR2 agonists are aspirated into the lungs, they induce neutrophils to leave the lungs in two mouse models of ARDS. The key roadblock to moving this into the clinic is that we need to know what the PAR2 agonist chemorepulsion mechanism is to anticipate potential drug interactions and side effects. To gain insights into a fundamental mechanism, and ways to induce neutrophils to leave a tissue, we propose to elucidate the AprA and PAR2 agonist chemorepulsion mechanisms using the power of Dictyostelium to lead the work. We will rigorously test newly identified Dictyostelium chemorepulsion pathway components, and determine where they function in the pathway. We will complete the Dictyostelium genetic screens to gain further insight into chemorepulsion, and then use this information to guide an examination of possibly similar mechanisms in neutrophils. While examining human neutrophil chemorepulsion, we observed a significant difference between male and female neutrophils, and we will delineate the extent and molecular mechanism underlying this difference. Together, the proposed work will elucidate a poorly understood fundamental mechanism, elucidate an unexpected sex difference in the innate immune system, and help elucidate how PAR2 agonists could be used clinically to drive excessive neutrophils out of a tissue, with possibly different treatments for men and women.