Synaptic signals that drive the long-term maintenance of homeostatic neuroplasticity

项目摘要 背景和目的：突触和神经回路具有强大的应激反应能力。 它们采用稳态调节机制来维持生理上适当的 突触输出关于突触可塑性的稳态形式的知识的提高应该会导致一个 更好地理解当突触稳定性丧失时发生的神经系统疾病。利用遗传 和电生理方法在模型果蝇神经肌肉接头（NMJ）突触， 发现了NMJ功能长期稳态维持所需的三个新因素， ered：两个酪氨酸激酶信号分子驻留在肌肉和磷脂酶C-β (PLCβ）分子驻留在神经元中。本提案的目的是了解这些 三种分子整合细胞-细胞信号传导过程以在整个生命中维持突触稳定性。 具体目标和研究设计：本项目有三个具体目标。前两个目标将 描述每种酪氨酸激酶如何驱动肌肉到神经的信号传导过程， 突触活动在很长一段时间的发展。第三个目标将解决神经元如何 PLCβ在突触处整合细胞-细胞信号以自主控制神经元输出。每个目标 将结合联合收割机电生理学、遗传学、药理学、生物化学和突触成像。一个首席- 每个目标的最新试验将是挑战NMJ功能-通常通过抑制谷氨酸受体， 肌肉-然后通过电生理学检查NMJ，以检查它是否适当地响应 通过从神经元释放更多的谷氨酸来应对挑战。通过结合这种电生理学 通过突触成像的方法，将有可能识别出特异性损害 突触功能-与其他参数相反，如突触生长。预期的结果是 突触组织如何传递细胞间信号以维持稳定活动水平的详细模型。 健康相关性：癫痫、共济失调和偏头痛等神经系统疾病与 神经元功能不稳定因此，了解突触如何工作以维持 分子水平可能对具有潜在神经元不稳定性的疾病具有深远的影响。 然而，对严格控制突触输出水平的细胞间信号传递事件的了解却很少。 遗传学上易处理的果蝇NMJ采用稳态策略来稳定突触 功能-如改变突触前钙离子内流的水平-这是由哺乳动物中枢神经系统共享的。 突触利用NMJ提供的分子和遗传工具， 阐明突触如何在整个生命过程中保持稳定功能的普遍保守机制。

PROJECT SUMMARY Background and Objectives: Synapses and circuits possess a robust capacity for stress response. They employ homeostatic regulatory mechanisms to maintain physiologically appropriate levels of synaptic output. Improved knowledge about homeostatic forms of synaptic plasticity should lead to a better understanding of neurological disorders that occur when synapse stability is lost. Using genetic and electrophysiological approaches at the model Drosophila neuromuscular junction (NMJ) synapse, three new factors required for the long-term homeostatic maintenance of NMJ function were uncov- ered: two tyrosine kinase signaling molecules residing in the muscle and one phospholipase C-β (PLCβ) molecule residing in the neuron. The objective of this proposal is to understand how these three molecules integrate cell-cell signaling processes to maintain synapse stability throughout life. Specific Aims and Research Design: This project has three specific aims. The first two aims will delineate how each respective tyrosine kinase drives a muscle-to-nerve signaling process to stabilize synaptic activity over long periods of developmental time. The third aim will address how neuronal PLCβ integrates cell-cell signals at the synapse to autonomously control neuronal output. Each aim will combine electrophysiology, genetics, pharmacology, biochemistry, and synapse imaging. A prima- ry assay for each aim will be to challenge NMJ function – usually by inhibiting glutamate receptors in the muscle – and then to examine the NMJ by electrophysiology to check if it appropriately responds to that challenge by releasing more glutamate from the neuron. By combining this electrophysiological approach with synapse imaging it will be possible to identify manipulations that specifically impair synapse function – as opposed to other parameters, like synapse growth. The expected outcome is a detailed model of how synaptic tissues transmit cell-cell signals to maintain stable activity levels. Health Relatedness: Neurological disorders like epilepsy, ataxia, and migraine are associated with unstable neuronal function. Therefore, understanding how synapses work to maintain stability on a molecular level could have profound implications for disorders with underlying neuronal instabilities. Yet the cell-cell signaling events that tightly control levels of synaptic output are poorly understood. The genetically tractable Drosophila NMJ employs homoestatic strategies to stabilize synapse function – such as altering levels of presynaptic calcium influx – that are shared by mammalian central synapses. Taking advantage of the molecular and genetic tools offered by the NMJ promises to shed light on universally conserved mechanisms of how synapses maintain stable function throughout life.