Collaboration between Phosphatidylserine receptors

摘要 细胞凋亡，或程序性细胞死亡，是发育、发病和组织中常见的现象 动态平衡。有效地清除凋亡细胞身体对于预防炎症和 潜在的破坏性免疫反应。出于这个原因，加强对凋亡身体的清除可能是一种 解决感染或侵袭性癌症治疗后破坏性炎症的有效策略 压倒内源性系统，清除凋亡细胞。开发这些疗法需要更深层次的 了解凋亡身体清除通路是如何被激活的。垂死的细胞招募吞噬细胞 通过‘吃我’信号，其中最普遍的是磷脂酰丝氨酸(PS)。几个PS识别问题 受体参与了细胞凋亡的清除，但其功能的许多方面仍不清楚。 不清楚：是每个受体调节身体清除途径的不同方面，还是它们是相加的 汇聚在相同的下游目标？PS受体是如何激活的？这种激活是如何实现的？ 转化为F-肌动蛋白重组和吞噬？特别是，磷脂酰丝氨酸受体(PSR) 在促进清除凋亡身体方面起着高度保守的作用，但PSR的机制 是否促进身体清理尚不得而知。我将研究两个保守的PS之间的合作- 识别受体，PS受体(PSR)和CED-1/Draper，使用C。 线虫与果蝇S2细胞内重组吞噬途径。在线虫的种系中，我将使用 双倒置选择性平面显微镜(DiSPIM)观察吞噬杯形成、F-肌动蛋白动力学和 身体清理效率。这将确定在死亡身体清除计划中的哪些步骤 受PSR-1和/或CED-1受体调节。为了快速剖析PSR功能的机制，我将 在果蝇S2细胞中重建凋亡身体清除途径。我的初步数据显示 异位表达dPSR可将S2细胞从贫乏的吞噬细胞转化为包被PS的高效吞噬细胞 玻璃微球。我将确定PSR是否使用Draper或F-actin将分区划分为活动的微域 质膜上的信号，无论是核的还是仅与膜结合的PSR信号都需要 促进吞噬，以及PSR是否被齐聚激活。总而言之，这些研究将使我们深入了解 PSR是一种高度保守但知之甚少的PS受体，并阐明了多发性PS是如何 受体相互协作以促进对凋亡细胞身体的清除。

Abstract Apoptosis, or programed cell death, is a common occurrence during development, pathogenesis and tissue homeostasis. The efficient removal of apoptotic cell corpses is crucial for preventing inflammation and a potentially damaging immune response. For this reason, enhancing apoptotic corpse clearance may be an effective strategy to resolve damaging inflammation following infection or aggressive cancer therapies that overwhelm the endogenous system for removing apoptotic cells. Developing these therapies requires a deeper understanding for how apoptotic corpse clearance pathways are activated. Dying cells recruit phagocytes through `eat me' signals, the most widespread of which is phosphatidylserine (PS). Several PS-recognizing receptors have been implicated in apoptotic corpse clearance but many aspects of their function are still unclear: does each receptor regulate distinct aspects of the corpse clearance pathway or do they additively converge on the same downstream targets? How are the PS receptors activated and how is this activation translated into F-actin reorganization and engulfment? In particular, the phosphatidylserine receptor (PSR) plays a highly conserved role in promoting clearance of apoptotic corpses, but the mechanism by which PSR promotes corpse clearance is not known. I will examine the collaboration between two conserved PS- recognizing receptors, the PS receptor (PSR) and CED-1/Draper, using a combination of in vivo imaging in C. elegans and reconstituting engulfment pathways in Drosophila S2 cells. In the C. elegans germline, I will use a dual inverted selective plane microscope (diSPIM) to examine phagocytic cup formation, F-actin dynamics and efficiency of corpse clearance. This will determine which steps in the apoptotic corpse clearance program are regulated by PSR-1, CED-1 or both receptors. To rapidly dissect the mechanism for PSR function, I will reconstitute the apoptotic corpse clearance pathway in Drosophila S2 cells. My preliminary data shows that ectopically expressing dPSR transforms S2 cells from poor phagocytes into efficient engulfers of PS-coated glass microspheres. I will determine if PSR partitions with Draper or F-actin into microdomains of active signaling in the plasma membrane, whether nuclear or only membrane-bound PSR signaling is required to promote engulfment, and if PSR is activated by oligomerization. Together, these studies will give insight into the function of PSR, a highly conserved yet poorly understood PS receptor, and elucidate how multiple PS receptors collaborate to promote clearance of apoptotic cell corpses.