Mechanisms of ATP Release from Glial Progenitors

胶质细胞释放的核苷酸在CMS中起着重要的自分泌和旁分泌信号作用 PNS。最近的研究表明，神经胶质细胞的非裂解性释放三磷酸腺苷可能涉及调控 通过核苷酸通透通道的胞吐或外流。胞外三磷酸腺苷作用于胞浆 离子型和代谢型P2X受体调节神经元活动，诱导钙瞬变 星形胶质细胞和产生关键的细胞内第二信使，例如与发育有关 在脑创伤后的神经胶质增生症以及神经干细胞的增殖和迁移中。最近，我们有 已有证据表明，神经前体细胞表现出高度自发的钙振荡 依赖于P2Rs的激活。嘌呤能受体拮抗剂或ATP降解剂的沐浴应用 APYRASE酶可预防自发性钙波动的发生。此外，封锁 P2Rs降低了这些祖细胞的增殖和迁移率。这些结果表明， 神经前体细胞有能力释放三磷酸腺苷，然后三磷酸腺苷发挥关键的自分泌、旁分泌信号。 在早期中枢神经系统发育中的作用。尽管识别参与递质释放的通路 胶质细胞被认为是成熟的星形胶质细胞，但对其发育方面一无所知。 从前体释放三磷酸腺苷的机制(S)。因此，这项拨款申请的目标是 为了评估星形胶质细胞是否以及处于哪个阶段发育，三种可能的途径 递质释放具有功能(胞外作用/分泌和通过亲离子的P2XRs扩散 和连接蛋白半通道)，并确定它们对钙振荡和细胞迁移的贡献。 免疫细胞化学、生化和药理学方法结合发光和 荧光成像将被用来识别ATP释放途径。这一标识对于 了解中枢神经系统发育和修复过程中正在进行的信号机制。

Nucleotide releasefrom glial cells plays important autocrine and paracrine signaling roles in the CMSand PNS. Recentstudies suggest that the non-lytic releaseof ATP from glial cells can either involve regulated exocytosis or efflux through nucleotide-permeable channels. Extracellular ATP acting onplasmalemmal ionotropic P2X and metabotropic P2Y receptors modulates neuronal activity, induces calcium transients in astrocytes and generatescritical intracellular second messengers implicated for instance in the development of gliosis following brain trauma and in the proliferation and migration of neural stem cells. Recently, we have obtained evidencethat neural progenitor cells display spontaneous calcium oscillations that are highly dependent on activation of P2Rs. Bath application of purinergic receptor antagonists or of the ATPdegrading enzyme apyrasepreventedthe occurrence of spontaneous calcium fluctuations. Moreover,blockade of P2Rs reduced the proliferation and the migration ratesof these progenitors. These results suggest that neural progenitors have the ability to release ATP,which then plays a crucial autocrine, paracrine signaling role during early CNS development.Although identification of pathways involvedon transmitter release from glial cells have been suggested for mature astrocytes, nothing is known about the developmental aspectsof the mechanism(s) by which ATP is released from precursors. Therefore, the goal of this grant application is to evaluate whether and at which stage of astrocyte development three of the putative pathways for transmitter release are functionally competent (excocytosis/secretion and diffusion through ionotropic P2XRs and connexin hemichannels) and to determine their contribution to calcium oscillations and cell migration. Immuocytochemical, biochemical and pharmacological approaches combined with luminescence and fluorecence imaging will be used to identify ATP release pathways. This identification is fundamental for the understanding of the signaling mechanisms ongoing during CNS development and repair.