Mechanisms Underlying Glial Regulation of Neuronal Excitability in Drosophila

我们建议使用果蝇作为一个模型系统，以确定神经胶质细胞钙振荡如何 偶联到K+缓冲和神经递质摄取以调节神经元兴奋性。神经胶质细胞， 包括星形胶质细胞，可以自发地和响应于 神经元活动，越来越多的证据表明星形胶质细胞的Ca 2+信号传导急性影响 神经生理学然而，人们对这一现象背后的分子机制知之甚少。 不同类型的神经胶质细胞Ca 2+信号以及它们如何调节神经元兴奋性。像 在哺乳动物中，我们发现果蝇胶质细胞显示微区Ca 2+振荡活性， 急性调节神经元功能和行为。果蝇有两种主要的神经胶质亚型， 与中枢神经系统中的神经元密切相关，并且与哺乳动物的神经元具有相同的特征。 星形胶质细胞--星形胶质细胞样胶质细胞和皮质胶质细胞。果蝇中枢神经系统分为 包含神经元细胞体的细胞皮层，以及包含所有神经元的突触神经元。 神经突和突触。星形胶质细胞和皮质神经胶质细胞类似地被划分为这些区域。 大脑区域，星形胶质细胞与突触和皮层神经胶质细胞周围的神经元 没有突触的细胞体因此，果蝇提供了一个理想的研究系统， 空间定位的神经胶质-神经元信号在胞体与突触。我们已经确定 果蝇皮层神经胶质特异性NCKX交换器中控制微区Ca 2+的突变 振荡，并且当失活时急性触发神经元癫痫发作。此外，我们还发现， 热激活TRPA 1通道的异位胶质表达可诱导快速的Ca 2+内流， 在皮质神经胶质细胞中的神经元癫痫发作，或在表达时的快速麻痹和神经元沉默， 星形胶质细胞使用无偏见的遗传抑制筛选行为癫痫发作和瘫痪 表型，我们已经产生了初始数据，表明Ca 2+内流控制膜 运输泄漏K+通道或神经递质转运蛋白，提供了一个意想不到的 神经胶质细胞Ca 2+振荡和神经胶质细胞在神经系统中更知名的作用之间的令人兴奋的联系， K+缓冲和神经递质清除。在当前的应用中，我们提出实验 这将为研究胶质细胞Ca ~（2+）振荡活性如何调节空间K ~（2+）提供基础 缓冲和神经递质摄取，以通过以下任一方式急性调节神经元兴奋性 神经胶质-胞体或神经胶质-突触相互作用。

We propose to use Drosophila as a model system for determining how glial Ca2+ oscillations couple to K+ buffering and neurotransmitter uptake to regulate neuronal excitability. Glial cells, including astrocytes, can increase their intracellular Ca2+ both spontaneously and in response to neuronal activity, and growing evidence indicates astrocytic Ca2+ signaling acutely influences neuronal physiology. However, little is known about the molecular machinery underlying different types of glial Ca2+ signals and how they act to regulate neuronal excitability. Like mammals, we have found that Drosophila glia display microdomain Ca2+ oscillatory activity that acutely regulates neuronal function and behavior. Drosophila has two main glial subtypes that are intimately associated with neurons in the CNS and that share features with mammalian astrocytes -- astrocyte-like glia and cortex glia. The Drosophila CNS is compartmentalized into the cell cortex that contains neuronal cell bodies, and the synaptic neuropil that contains all neurites and synapses. Astrocytes and cortex glia are similarly compartmentalized into these brain regions, with astrocytes associating with synapses and cortex glia surrounding neuronal somas that are devoid of synapses. As such, Drosophila provides an ideal system to study spatially-localized glial-neuronal signaling at somas versus synapses. We have identified mutations in a Drosophila cortex glial-specific NCKX exchanger that controls microdomain Ca2+ oscillations and that acutely triggers neuronal seizures when inactivated. In addition, we found that ectopic glial expression of a heat-activated TRPA1 channel can induce rapid Ca2+ influx and neuronal seizures in cortex glial, or rapid paralysis and neuronal silencing when expressed in astrocytes. Using unbiased genetic suppressor screens for the behavioral seizure and paralysis phenotypes, we have generated initial data that indicates Ca2+ influx controls membrane trafficking of either leak K+ channels or neurotransmitter transporters, providing an unexpected and exciting connection between glial Ca2+ oscillations and the more well-known roles of glia in K+ buffering and neurotransmitter clearance. In the current application, we propose experiments that will provide a foundation to examine how glial Ca2+ oscillatory activity modulates spatial K+ buffering and neurotransmitter uptake to acutely modulate neuronal excitability through either glial-soma or glial-synapse interactions, respectively.