Deciphering the mechanism of SHIP1 regulation in human neutrophils

研究总结声明 免疫细胞解释环境中的化学信号，并做出决定，控制自己的命运。为 例如，人类中性粒细胞通常通过极化和向化学源迁移来对信号做出反应。 对这些细胞功能至关重要的是细胞表面受体、小GTP酶和 合成磷脂酰肌醇磷酸(PIP)脂类的酶。这项研究旨在破译 在血浆中控制这些不同类别的信号分子之间的通信的机制 薄膜。利用人的中性粒细胞，我们发现了CDC42 GTP酶和一种名为SHIP1的脂质磷酸酶 触发分子信号，以行波的形式在质膜上传播。这 行为，即所谓的兴奋性，涉及膜上和膜外蛋白质募集的重复循环。这个 本研究的目的是确定SHIP1如何通过整合信号来调节可兴奋的信号网络 来源于脂类和膜系留蛋白。使用各种体外生物化学技术，包括 支持膜技术和单分子成像，我们将确定如何控制脂质成分 SHIP1膜结合和磷酸酶活性(目标1)。使用调节兴奋性的因素 在细胞信号网络中，我们将重构控制SHIP1膜募集、释放的机制 自我抑制和激活(目标2)。同时，我们将使用基于CRISPR的基因组编辑、光遗传学、 以及荧光生物传感器的定量活细胞成像，以阐明PIP脂类之间的通讯 Small GTP酶受SHIP1调控。使用这些工具，我们将确定SHIP1作为信令的角色 网络支架与脂质磷酸酶(目标3)。总的来说，这项研究将把膜生物物理学和细胞学结合起来。 生物学解释PIP脂类、小GTP酶和SHIP1如何协同控制可兴奋信号 中性粒细胞中的网络和细胞迁移。通过解开白细胞如何感知、解释和响应 致病信号我们将填补关于这些信号分子如何协调细胞的知识空白 运动与潜在的可兴奋网络。这一发现可能会为研究人员打开发展的大门 新的治疗方法可以用来调节免疫细胞的功能，以对抗感染， 炎症和癌症。

Research Summary Statement Immune cells interpret chemical cues in their environment and make decisions that control their fate. For example, human neutrophils often respond to signals by polarizing and migrating toward the chemical source. Critical for these cellular functions is the dynamic interplay between cell surface receptors, small GTPases, and the enzymes that synthesize phosphatidylinositol phosphate (PIP) lipids. This study aims to decipher the mechanisms the control communication between these different classes of signaling molecules at the plasma membrane. Using human neutrophils, we find that Cdc42 GTPase and a lipid phosphatase denoted SHIP1 trigger a molecular signal that propagates across the plasma membrane in the form of a traveling wave. This behavior, coined excitability, involves repetitive cycles of protein recruitment ON and OFF the membrane. The goal of this study is to determine how SHIP1 regulates the excitable signaling network by integrating signals derived from lipids and membrane tethered proteins. Using a variety of in vitro biochemistry techniques, including supported membrane technology and single molecule imaging, we will determine how lipid composition controls SHIP1 membrane association and phosphatase activity (Aim 1). Using factors that regulate the excitable signaling network in cells, we will reconstitute mechanisms that control SHIP1 membrane recruitment, release of autoinhibition, and activation (Aim 2). In parallel, we will use CRISPR based genome editing, optogenetics, and quantitative live cell imaging of fluorescent biosensors to elucidate how communication between PIP lipids and small GTPase is regulated by SHIP1. Using these tools we will determine the role SHIP1 serves as signaling network scaffold versus a lipid phosphatase (Aim 3). Overall, this study will unify membrane biophysics and cell biology to explain how PIP lipids, small GTPases, and SHIP1 synergistically control the excitable signaling network and cell migration in neutrophils. By unraveling how white blood cells sense, interpret, and respond to pathogenic signals we will fill a gap in knowledge concerning how these signaling molecules coordinate cellular movement with the underlying excitable network. This discovery could open doors for researchers to develop new therapeutics that can be used to modulate immune cell functions in ways that combat infection, inflammation, and cancer.