Autocrine control of neutrophil chemotaxis

趋化性允许多形核中性粒细胞（PMN）迅速到达感染和发炎部位。尽管最近的进展，我们的理解趋化性，许多悬而未决的问题仍然存在。趋化因子刺激中性粒细胞释放ATP，并通过嘌呤能受体的自分泌反馈回路控制趋化性。在这个项目中，我们修改了拟议工作的范围，以了解趋化信号如何诱导ATP释放，以及从释放的ATP形成的腺苷如何控制负反馈回路，这些负反馈回路在定义细胞极性和尾足收缩中起着关键作用。拟议的项目基于以下修订的工作假设：刺激化学引诱物受体诱导快速的细胞内事件，导致ATP释放。通过不同机制释放的额外ATP为抑制性A2a腺苷受体提供配体腺苷。这些受体增加后退边缘的cAMP水平，提供抑制性反馈回路，从而激发全局抑制并促进尾足收缩，确定细胞极性并促进迁移。我们建议通过解决以下经修订的具体目标来检验这一工作假设： 具体目标1。上游事件导致ATP释放我们将确定上游信号通路，连接趋化受体激活和ATP释放梯度传感过程中。此外，我们还将研究不同的ATP释放机制及其在梯度感应、细胞极化和迁移过程中对ATP释放的贡献。重点将放在趋化性受体下游的信号传导途径上，钙信号传导和MAPK活化，其导致ATP释放通道（如连接蛋白或泛连接蛋白）的打开和ATP经由囊泡转运的释放。 具体目标2。整体抑制和嘌呤能信号传导我们将研究嘌呤能受体，例如，A2a或A2b腺苷受体诱导定义极性并促进细胞迁移的全局抑制。重点将放在抑制下游信号通路，引起全球抑制。我们将重点关注腺苷酸环化酶、PKA和cAMP积累的激活。此外，我们将研究这些信号事件如何阻止梯度传感和诱导Rho激活和肌球蛋白的形成，诱导尾足收缩在后退边缘。 这些机制的知识将进一步定义嘌呤能机制，控制趋化性，并可能使我们构思新的治疗策略，旨在治疗这些嘌呤能反应，以治疗炎症和感染性疾病。

Chemotaxis allows polymorphonuclear neutrophils (PMN) to rapidly reach infected and inflamed sites. Despite recent progress in our understanding of chemotaxis, many open questions still remain. Chemoattractants stimulate the release of ATP from PMN and autocrine feedback loops via purinergic receptors control chemotaxis. In this project we revised the the scope of the proposed work to understand how the chemotactic signals induce ATP release and how adenosine formed from the released ATP controls negative feedback loops that play a critical role in defining cell polarity and uropod retraction. The proposed project rests on the following revised working hypothesis: Stimulation of chemoattractant receptors induces rapid intracellular events that result in ATP release. Additional ATP release through distinct mechanisms provides the ligand, adenosine, for suppressive A2a adenosine receptors. These receptors increases cAMP levels at the receding edge, providing an inhibitory feedback loop that elicits global inhibition and promotes uropod contraction, defining cell polarity and promoting migration. We propose to test this working hypothesis in by addressing the following Revised Specific Aims: Specific Aim 1. Upstream events leading to ATP release We will determine the upstream signaling pathways that link chemotactic receptor activation and ATP release during gradient sensing. In addition, we will examine different ATP release mechanisms and their contributions to ATP release during gradient sensing, cell polarization, and migration. Emphasis will be placed on the signaling pathway downstream of chemotactic receptors e.g., calcium signaling and MAPK activation that lead to the opening of ATP release channels such as connexins or pannexins and release of ATP via vesicular transport. Specific Aim 2. Global inhibition and purinergic signaling We will study if and how purinergic receptors, e.g., A2a or A2b adenosine receptors induce global inhibition that defines polarity and promotes cell migration. Emphasis will be placed on the suppressive down-stream signaling pathways that elicit global inhibition. We will focus on activation of adenylate cyclases, PKA, and cAMP accumulation. In addition, we will examine how these signaling events block gradient sensing and induce Rho activation and myosin formation that induces uropod contraction at the receding edge. Knowledge of these mechanisms will further define the purinergic mechanisms that control chemotaxis and may allow us to conceive novel therapeutic strategies aimed at treating these purinergic responses to treat inflammatory and infectious diseases.