Release of find-me signals during apoptotic cell clearance

在几乎所有的组织中，通常通过细胞凋亡过程，存在细胞的持续更新。在 在健康的组织中，垂死的细胞被吞噬细胞迅速识别和清除。然而，在这方面， 未能及时清除凋亡细胞导致其继发性坏死，释放毒性物质， 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可溶性因子“宣告”它们的存在， “发现我信号”吸引吞噬细胞，从而促进其迅速清除。初始 该提案的主要研究者的研究已经确定了核苷酸ATP， UTP作为一种类型的“发现我的信号”，这是关键的凋亡细胞清除在体外和体内， 体内;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 该通道介导凋亡细胞的核苷酸释放。总体假设检验， 这一建议是，核苷酸find-me信号的泛连接蛋白通道依赖性释放 凋亡细胞，随后的吞噬细胞的感知对于适当的细胞清除是重要的 在体内，Panx 1介导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，寻求新的理解，这将允许操纵“查找- 我通过这些渠道释放信号。在目标2中，我们使用条件性细胞特异性Panx 1敲除 小鼠和条件转基因小鼠，以确定Panx 1通道的操作是否影响细胞 体内清除率。为此，我们利用了一个模型，其中有证据表明细胞清除 在正常组织内稳态和疾病中是重要的-即，胸腺发育 总的来说，我们希望这些研究能够产生新的机械理解， find-me信号的调节释放影响细胞清除，并更好地定义这种模式， 死亡细胞和吞噬细胞之间的细胞间通讯， 自身免疫这些研究还可以为将Panx 1通道视为一种 用于治疗开发合适靶点。

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 discovery 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 and conditional transgenic mice to determine if manipulation of Panx1 channels affects cell clearance in vivo. For this, we take advantage of a model where evidence suggests cell clearance is important in normal tissue homeostasis and in disease – i.e., thymic development. 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. These studies can also provide a rationale for considering Panx1 channels as a suitable target for therapeutic development.