Release of find-me signals during apoptotic cell clearance

在几乎所有的组织中，细胞都有不断的更替，通常是通过细胞凋亡的过程。在……里面 在健康的组织中，死亡的细胞很快就会被吞噬细胞识别和清除。然而， 未能及时清除凋亡细胞会导致它们的继发性坏死，释放有毒物质 胞浆内容物，以及组织内的炎症。目前的证据表明， 在死亡过程的早期，凋亡细胞通过被称为“可溶性因子”的 ‘Find-Me Signals’吸引吞噬细胞，从而促进其迅速清除。首字母 这项提议的主要研究人员的研究已经确定了核苷酸ATP和 UTP作为一种‘Find-Me信号’，在体外和体外对细胞的凋亡清除是至关重要的 活体；随后的研究导致了一个关键发现，即膜蛋白pAnnexin 1(Panx1)是 介导从凋亡细胞中释放核苷酸的通道。中测试的总体假设 这一提议是依赖于pAnnexin通道的核苷酸Find-Me信号从 细胞的凋亡和吞噬细胞随后的感知对于适当的细胞清除是重要的 且Panx1介导Find-Me信号通路的破坏将有助于 疾病。在我们初步研究的基础上，在目标1中，我们研究了一种新的 Panx1激活机制，寻求新的理解，以允许操纵`Find- 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Panx1基因敲除 小鼠和条件转基因小鼠确定Panx1通道的操作是否影响细胞 体内清除。为此，我们利用了一个模型，在该模型中，有证据表明细胞清除 对正常组织的动态平衡和疾病--即胸腺发育--非常重要。 总而言之，我们希望这些研究能够产生新的机械性理解，即 Find-Me信号的调节释放会影响细胞清除，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 自身免疫力。这些研究还可以为将Panx1通道视为 适合于治疗发展的靶点。

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.