Release of find-me signals during apoptotic cell clearance

描述（由申请人提供）：在几乎所有组织中，通常通过细胞凋亡过程进行细胞的持续更新。在健康的组织中，垂死的细胞很快被吞噬细胞识别和清除。然而，未能及时清除凋亡细胞导致其继发性坏死，释放有毒细胞质内容物和组织内的炎症。目前的证据表明，凋亡细胞在死亡过程的早期通过称为“发现我信号”的可溶性因子“广告”它们的存在，以吸引吞噬细胞，从而促进它们的迅速清除。该提案的主要研究者的初步研究已经将核苷酸ATP和UTP确定为一种类型的“发现我信号”，这对体外和体内凋亡细胞清除至关重要;随后的研究导致了一个关键发现，即膜蛋白泛连接蛋白1（Panx 1）是介导凋亡细胞释放核苷酸的通道。在该提议中测试的总体假设是，来自凋亡细胞的核苷酸find-me信号的泛连接蛋白通道依赖性释放以及随后的吞噬细胞的感测对于体内适当的细胞清除是重要的，并且Panx 1介导的find-me信号通路的破坏将有助于疾病。基于我们的初步研究，在目标1中，我们研究了一种新的Panx 1激活机制的分子基础，寻求新的理解，这将允许通过这些通道操纵“找到我”信号释放。在目标2中，我们使用条件性细胞特异性Panx 1敲除小鼠来确定Panx 1通道的操作是否影响体内细胞清除。为此，我们利用两种模型，新的证据表明细胞清除在正常组织稳态和疾病中是重要的-即，胸腺发育和气道炎症。总的来说，我们希望这些研究能够对find-me信号的调节释放如何影响细胞清除产生新的机制理解，并更好地定义垂死细胞和吞噬细胞之间的这种细胞间通讯模式，并对自身免疫和气道炎症产生影响。这些研究也可以为考虑Panx 1通道作为治疗开发的合适靶点提供理论基础。

DESCRIPTION (provided by applicant): In nearly all tissues, there is a continual turnover of cells, usually by the process of apoptosis. In healthy tissues, the dying cells are quickly recognized and cleared by phagocytes. However, failure to promptly clear apoptotic cells leads to their secondary necrosis, release of toxic cytoplasmic contents, and inflammation within tissues. Current evidence suggests that the apoptotic cells 'advertise' their presence early on in the death process, via soluble factors termed 'find-me signals' to attract phagocytes, and thereby promote their prompt clearance. Initial studies from the Principal Investigators of this proposal have identified the nucleotides ATP and UTP as one type of 'find-me signal' that is critical for apoptotic cell clearance in vitro and in vivo; subsequent studies led to a key discovey that the membrane protein pannexin 1 (Panx1) is the channel mediating nucleotide release from apoptotic cells. The overall hypothesis tested in this proposal is that pannexin channel-dependent release of nucleotide find-me signal from apoptotic cells, and subsequent sensing by phagocytes is important for proper cell clearance in vivo, and that disruption of the Panx1-mediated find-me signal pathway would contribute to diseases. Based on our preliminary studies, in Aim 1, we study the molecular basis of a novel Panx1 activation mechanism, seeking new understanding that will allow manipulation of 'find-me' signal release via these channels. In Aim 2, we use conditional cell-specific Panx1 knockout mice to determine if manipulation of Panx1 channels affects cell clearance in vivo. For this, we take advantage of two models for which new evidence suggests cell clearance is important in normal tissue homeostasis and in disease - i.e., thymic development and airway inflammation. Collectively, we expect these studies to yield new mechanistic understanding on how the regulated release of find-me signals influence cell clearance, and better define this mode of inter-cellular communication between dying cells and phagocytes, with implications for autoimmunity and airway inflammation. These studies can also provide a rationale for considering Panx1 channels as a suitable target for therapeutic development.