How discrete homeostatic signals stabilize synapse function across time

项目总结 背景和目的：突触和回路具有保持其输出稳定的强大能力。 利用果蝇的黑腹神经肌肉接头(NMJ)作为突触的模型，最近许多实验室已经 识别了数十个通过非Hebbian基因稳定突触功能的信号分子和过程 一种称为突触前稳态增强(PHP)的稳态神经可塑性。这些发现提供了一个 丰富的储集层用于发现科学，但在这一点上，我们对几十个离散的 动态平衡信号分子整合成连贯的系统，随着时间的推移稳定突触功能。这个 这个建议的目的是解决这个问题，结合遗传学、药理学、成像、生物化学和 电生理学。最终，对自稳形式的突触可塑性的了解的提高可能会导致 更好地了解当突触失去稳定性时发生的神经障碍。 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可以在几分钟内迅速诱发，然后长期维持数天。第一个目标是定义一个 在PHP诱导的开始几分钟内发生的事件序列。为了达到这个目的，我们利用 基因筛查的一个偶然发现：肌肉中伴侣功能受损会减缓PHP信号。 使用这一遗传工具，我们将描绘出肌肉信号传递给神经的过程顺序 并能促进释放。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。我们将应用这一点 一种新的方法来表征大约25种影响PHP持续维持的已知遗传条件。 我们希望定义不同的PHP信令模式。在我们的目标之间，预期的结果是 突触如何通过整合跨越时间阶段的多个信号来维持体内平衡功能。 与健康相关：癫痫、共济失调和偏头痛等神经疾病与不稳定有关 神经功能。了解突触如何在分子水平上维持稳定可能会有助于- 发现了潜在神经元不稳定的障碍的影响。然而，严密控制的信号事件 人们对突触输出的水平知之甚少。易驯服的果蝇NMJ采用同态策略 为了稳定突触功能-例如改变突触前钙内流的水平-由 哺乳动物的中央突触。利用NMJ承诺提供的分子和遗传工具 阐明突触如何在整个生命中保持稳定功能的普遍保守的机制。

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.