How discrete homeostatic signals stabilize synapse function across time

项目摘要 背景和目的：突触和神经回路具有保持输出稳定的强大能力。 利用果蝇神经肌肉接头（NMJ）作为模型突触，许多实验室最近 确定了几十种信号分子和过程，通过非赫布的 这种形式的稳态神经可塑性称为突触前稳态增强（PHP）。这些发现提供了一个 丰富的水库发现科学，但在这一点上，我们几乎没有了解如何几十个离散的 稳态信号分子整合到连贯系统中，随着时间的推移稳定突触功能。的 该提案的目的是结合遗传学、药理学、成像学、生物化学和 电生理学最终，对突触可塑性的稳态形式的了解的提高可能会导致 更好地理解当突触稳定性丧失时发生的神经系统疾病。 具体目标和研究设计：本项目有两个具体目标。我们知道果蝇体内的PHP NMJ可以在几分钟内急性诱导，然后长期维持数天。第一个目标是定义一个 在PHP入门的开始几分钟内发生的一系列事件。为此，我们利用 基因筛选的一个偶然发现：肌肉中伴侣蛋白功能受损会减缓PHP信号传导。 利用这种遗传工具，我们将描绘出肌肉向神经发出信号时发生的过程顺序 并促进释放。对于第二个目标，我们开发了一种新的药理学方法来监测 PHP的诱导、急性表达和长期维持之间的过渡期。我们将应用这个 一种新的方法来表征大约25种已知的影响PHP持续维持的遗传条件。 我们希望定义不同的PHP信号形式。在我们的目标之间，预期的结果是一个模型， 突触如何通过整合多个信号来维持稳态功能。 健康相关性：神经系统疾病如癫痫、共济失调和偏头痛与不稳定的 神经元功能了解突触如何在分子水平上维持稳定性，可能有助于 发现了潜在的神经元不稳定性疾病的影响。然而，这些信号事件， 突触输出的水平知之甚少。易处理的果蝇NMJ采用了稳态策略 稳定突触功能，如改变突触前钙离子流入水平， 哺乳动物的中央突触利用NMJ提供的分子和遗传工具， 揭示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 keeping their outputs stable. Using the Drosophila melanogaster neuromuscular junction (NMJ) as a model synapse, many labs have recently identified dozens of signaling molecules and processes that stabilize synapse function through a non-Hebbian form of homeostatic neuroplasticity called presynaptic homeostatic potentiation (PHP). These findings offer a rich reservoir for discovery science, but at this point we have little understanding of how dozens of discrete homeostatic signaling molecules integrate into coherent system that stabilizes synapse function over time. The objective of this proposal is to solve that problem combining genetics, pharmacology, imaging, biochemistry, and electrophysiology. Ultimately, improved knowledge about homeostatic forms of synaptic plasticity could lead to a better understanding of neurological disorders that occur when synapse stability is lost. Specific Aims and Research Design: This project has two specific aims. We know that PHP at the Drosophila NMJ can be acutely induced in minutes and then chronically maintained for days. The first aim is to define a sequence of events that occurs during the opening minutes of PHP induction. For this aim, we take advantage of a serendipitous finding from a genetic screen: impaired chaperone function in the muscle slows PHP signaling. Using this genetic tool we will delineate an order of processes that occurs as the muscle signals to the nerve and potentiates release. For the second aim, we developed a new pharmacological approach to monitor the transition periods between induction, acute expression, and long-term maintenance of PHP. We will apply this new method to characterize about 25 known genetic conditions that impact the sustained maintenance of PHP. We expect to define distinct PHP signaling modalities. Between our aims, the expected outcome is a model of how a synapse can sustain homeostatic function by integrating multiple signals across phases of time. Health Relatedness: Neurological disorders like epilepsy, ataxia, and migraine are associated with unstable neuronal function. Understanding how synapses work to maintain stability on a molecular level could have pro- found implications for disorders with underlying neuronal instabilities. Yet the signaling events that tightly control levels of synaptic output are poorly understood. The 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.