Neuromodulator signaling and activity in the C. elegans egg-laying circuit

项目摘要 这个项目的长期目标是以前所未有的精度描绘出所有 模型神经回路中的神经递质信号事件共同产生其动态活动模式。 神经回路是大脑功能的基本单位，神经回路内信号的改变会扰乱回路 产生情绪障碍和其他人类大脑疾病的功能。到目前为止，我们对这种 疾病仍然是模糊的，因为我们只了解许多疾病中的每一个中的几个单独的特征 已经研究过的不同神经回路。因此，我们的方法是分析所有信令事件 在一个简单的神经电路中，预期这将产生对一般神经电路如何的新见解 工作。这种方法的灵感来自于过去在生物学其他领域取得的成功，在这些领域中，对简单的 在遗传上容易控制的生物体中的模型(例如，在大肠杆菌中的乳胶操纵子或在果蝇中的模式形成 胚胎)导致了概念性的突破，并推广到人类生物学。因此，我们正在加紧研究 线虫的简单产卵电路，在这个实验系统中，我们开发了一种强大的 遗传、光遗传、化学发生和钙成像方法的组合，这些方法一起可以提供 对电路功能的前所未有的机械洞察力。我们的分析已经发现了两个实例 小分子神经递质与共同释放的神经肽一起发出信号，而且正在进行 电路活动对来自突触后细胞的动态平衡反馈做出反应。这些特征很可能是 在其他神经回路中是保守的。在这个项目的下一阶段，我们的目标是了解产卵是如何 电路自动开启。该电路在~20分钟的非活动阶段和~2.5分钟的周期之间交替 有节奏的活动。我们最近的工作表明，两个HSN命令神经元释放出一种组合的 5-羟色胺和由NLP-3基因编码的神经肽来激活电路。这些神经调节剂发出信号 通过至少五种受体改变突触后肌肉对乙酰胆碱的反应 突触前运动神经元。 目的1.我们将确定HSN神经元如何“决定”何时释放5-羟色胺和NLP-3神经肽 来激活电路。 目的2.我们将确定一组不同的5-羟色胺和NLP-3神经肽受体如何改变 电路的各种特定单元，以使电路活动。 目的3.我们将鉴定与HSN释放的5-羟色胺和NLP-3神经肽作用的细胞和信号 帮助激活环路，并最终触发产卵肌肉收缩。

Project Summary The long-term goal of this project is to delineate at an unprecedented level of precision how all the neurotransmitter signaling events within a model neural circuit together produce its dynamic pattern of activity. Neural circuits are a basic unit of brain function, and altered signaling within neural circuits can disrupt circuit function to produce mood disorders and other human brain diseases. To date, our understanding of such diseases remains vague because we understand only a few individual features within each of the many different neural circuits that have been studied. Therefore, our approach is to analyze all the signaling events within one simple neural circuit, anticipating that this will yield new insights into how neural circuits in general work. This approach is inspired by past successes in other areas of biology in which deep analysis of a simple model in a genetically tractable organism (e.g. the lac operon in E. coli or pattern formation in the Drosophila embryo) led to conceptual breakthroughs that generalized to human biology. Thus, we are intensely studying the simple egg-laying circuit of C. elegans, an experimental system in which we have developed a powerful combination of genetic, optogenetic, chemogenetic, and Ca2+ imaging approaches that together can provide unprecedented mechanistic insights into circuit function. Our analysis has already discovered two instances in which a small-molecule neurotransmitter signals alongside co-released neuropeptides, and also that ongoing circuit activity responds to homeostatic feedback from the postsynaptic cells. These features are likely conserved in other neural circuits. In the next period of this project we aim to understand how the egg-laying circuit turns itself on. This circuit alternates between ~20 minute inactive phases and ~2.5 minute periods of rhythmic activity. Our recent work shows that the two HSN command neurons release a combination of serotonin and neuropeptides encoded by the nlp-3 gene to activate the circuit. These neuromodulators signal through a set of at least five receptors to alter the postsynaptic muscle response to acetylcholine released from presynaptic motor neurons. Aim 1. We will determine how the HSN neurons “decide” when to release serotonin and NLP-3 neuropeptides to activate the circuit. Aim 2. We will determine how a diverse set of receptors for serotonin and NLP-3 neuropeptides alter activity of various specific cells of the circuit to make the circuit active. Aim 3. We will identify the cells and signals that act with HSN-released serotonin and NLP-3 neuropeptides to help activate the circuit and ultimately trigger egg-laying muscle contraction.