Role of the purine nucleotide messengers cyclic ADP-ribose and ADP-ribose in T-lymphocyte biology

P2X7和TRPM2是T淋巴细胞表达的阳离子通道，分别由胞外和胞内腺嘌呤核苷酸门控。此外，P2X7还介导膜对包括核苷酸和药物在内的多种底物的通透性变化。尽管越来越多的证据表明这两种通道在炎症中发挥了关键作用，但它们对T细胞的影响仍不清楚。因此，本项目的主要目标是确定P2X7和TRPM2在T细胞激活的早期事件中的作用。为此，我们将使用活细胞钙离子和三磷酸腺苷成像、高效液相色谱和膜片钳技术来研究这些通道在TCR信号转导中的作用。特别是，我们将检验这一假设，即2‘-脱氧腺苷二磷酸核糖(2’-脱氧-ADPR)而不是ADPR是TRPM2的主要内源性激活配体，并表征P2X7诱导的T细胞对核苷酸和其他信号分子通透性的变化，从而在细胞内和细胞外核苷酸的信号转导世界之间提供联系。确定P2X7和TRPM2在TCR信号中的作用将为评估针对这两个离子通道的新治疗策略的潜力提供基础。

P2X7 and TRPM2 are cation channels expressed by T lymphocytes that are gated by extra- and intracellular adenine nucleotides, respectively. P2X7, in addition, mediates membrane permeability changes towards multiple substrates including nucleotides and drugs. Although increasing evidence points to a pivotal role of both channels in inflammation, their effects on T cells remain unclear. The primary goal of the current project is thus to characterize the roles of P2X7 and TRPM2 during the early events of T cell activation. To this end, we will use live cell Ca2+ and ATP imaging, HPLC, and patch-clamp techniques to study the roles of these channels in TCR signaling. Especially, we will test the hypothesis that 2`-deoxy-adenosine diphosphoribose (2´-deoxy-ADPR), instead of ADPR, is the major endogenous activating ligand of TRPM2, and characterize P2X7-induced changes in T cell permeability to nucleotides and other signaling molecules, thereby providing a link between the worlds of signaling by intra- and extracellular nucleotides. Characterization of the roles of P2X7 and TRPM2 in TCR signaling will provide the basis for assessing the potential of new therapeutic strategies aimed at targeting these two ion channels.