Signal Integration in Neutrophil Chemotaxis

描述（由申请人提供）：中性粒细胞是先天性免疫细胞，使用定向迁移来捕获和杀死细菌。这种定向迁移取决于几种基本的信令能力。中性粒细胞可以迁移到跨越几个数量级的趋化梯度，需要信号适应，使细胞响应相对变化，而不是稳态浓度的配体。中性粒细胞产生一致的内部极性，不依赖于外部梯度的陡度，需要正反馈来放大微妙的信号不对称和长程抑制，使得突起可以彼此竞争以产生主导前沿。通过遗传和药理学功能丧失实验，我们知道趋化性所需的许多核心成分。然而，我们对这些信号成分如何相互作用以产生细胞极性和运动的理解仍然存在根本性的差距。由于极性的整个过程非常复杂，我们开发了一些工具来隔离和剖析信号级联中的各个步骤，以更好地理解整个信号电路。在过去的一年中，我们开发了一种通用的方法，用于哺乳动物细胞内信号的定量光遗传学控制。该系统为我们提供了前所未有的空间和时间控制范围广泛的细胞内信号，并将使我们能够解剖的逻辑信号处理的方式，已经不可能与传统的工具。细胞内信号的定量控制在揭示动作电位的逻辑中发挥了重要作用 和细菌的趋化性，我们设想我们的光遗传学工具将同样具有变革性，用于理解中性粒细胞中的细胞极性。我们的具体目标是了解感觉适应，占显着的动态范围的趋化性（目标1），并剖析正反馈回路（目标2）和长距离抑制（目标3），使中性粒细胞极性可能。

DESCRIPTION (provided by applicant): Neutrophils are innate immune cells that use directed migration to hunt and kill bacteria. This directed migration depends on several fundamental signaling capabilities. Neutrophils can migrate up chemotactic gradients spanning several orders of magnitude, requiring signaling adaptation so that cells respond to relative changes rather than steady-state concentrations of ligand. Neutrophils generate a consistent internal polarity that does not depend on the steepness of the external gradient, requiring positive feedback to amplify subtle signaling asymmetries and long-range inhibition so that protrusions can compete with one another to generate a dominant leading edge. Through genetic and pharmacological loss-of-function experiments, we know many of the core components required for chemotaxis. However, there are still fundamental gaps in our understanding of the how these signaling components interact to generate cell polarity and movement. Because the overall process of polarity is highly complex, we have developed tools to isolate and dissect individual steps in the signaling cascade to better understand the overall signaling circuit. In the last gran period, we developed a general approach for quantitative optogenetic control of intracellular signaling in mammalian cells. This system gives us unprecedented spatial and temporal control of a wide range of intracellular signals and will enable us to dissect the logic of signal processing in a manner that has not been possible with conventional tools. Quantitative control of intracellular signals has played a fundamental role in uncovering the logic of action potentials and bacterial chemotaxis, and we envision that our optogenetic tools will be similarly transformative for understanding cell polarity in neutrophils. Our specific aims are to understand the sensory adaptation that accounts for the remarkable dynamic range of chemotaxis (Aim 1) and to dissect the positive feedback loops (Aim 2) and long-range inhibition (Aim 3) that make neutrophil polarity possible.