Intercellular Signaling in the Circadian Clock

描述（由申请人提供）：生物钟缺陷与多种临床疾病有关。新出现的证据暗示神经元之间的通信同步和维持生物钟。果蝇一直是一个强有力的模型来阐明生物钟的潜在机制，其中许多方面与人类高度保守。在果蝇中，神经肽色素分散因子（PDF）是同步神经起搏器和调节神经输出的核心。我们最近发现了PDF的g蛋白偶联受体（PDFR）。该受体的鉴定为解决与昼夜节律起搏器功能相关的核心问题提供了机会。生物钟是如何驱动下游神经回路来控制行为的，比如睡眠和醒来？PDF在神经振荡耦合中的作用是什么？PDF重置核心振荡器并驱动有节奏行为的机制是什么？

DESCRIPTION (provided by applicant): Defects in circadian clocks have been implicated in a variety of clinical disorders. Emerging evidence implicates communication between neurons in synchronizing and sustaining circadian clocks. The fruit fly Drosophila has been a powerful model to elucidate the underlying mechanisms of clocks, many aspects of which are highly conserved with humans. In the fruit fly, the neuropeptide PIGMENT DISPERSING FACTOR (PDF) is central to synchronizing neural pacemakers and regulating neural outputs. We have recently identified the G-protein coupled receptor for PDF (PDFR). The identification of this receptor affords an opportunity to address central questions related to circadian pacemaker function. How do circadian clocks drive downstream neural circuits to control behavior, such as sleep and wake? What is the role of PDF in coupling of neural oscillators? What are the mechanisms by which PDF resets core oscillators and drives rhythmic behaviors? The specific aims of the proposal are: 1. To map the cellular substrates of PDF receptor function in behavioral and molecular circadian rhythms. Remarkably little is known about the neural substrates that mediate PDF receptor action in circadian behavior. To address this issue, we will use tissue-specific PDFR rescue and overexpression in circadian and potential downstream neural circuits. In addition, we will assess the distribution of PDFR in the brain. 2. To examine the role of PDF signaling in coupling of neural circadian pacemakers. To assay coupling, we will manipulate the speed of the clock in subsets of the circadian neural network and assay the consequences on interconnected oscillators in the presence or absence of PDF signalling. 3. To examine the molecular mechanisms by which PDF resets the core circadian clock and output pathways. We will examine the molecular consequences of loss of PDFR on the core clock as well as cAMP and MAPK signalling pathways. Using novel electrophysiological approaches, we will examine the effects of exogenous PDF on electrical properties of pacemaker and output neurons. We will analyze genetic interactions between PDF/PDFR, core clock, cAMP/MAPK, and membrane excitability mutants. These studies should elucidate the molecular and neural circuitry essential for PDFR action in circadian behavior. They also exploit the unique advantages of the Drosophila system, including the ease of tissue-specific rescue studies, the ability to manipulate the clock in identified subsets of pacemaker neurons, and the extensive genetic resources to examine signalling pathways and the core clock in the whole animal. Given the conservation with mammalian systems, this work should provide insights into the mechanisms by which neuropeptides mediate normal and disrupted circadian rhythms in human disease. Project Narrative Defects in circadian clocks have been implicated in a variety of clinical disorders. Communication between neural pacemakers and to their downstream targets is mediated by neuropeptides. We will elucidate the role of a circadian neuropeptide in synchronizing circadian clocks and communicating timing information in a simple animal model. Given the potential conservation with humans, this work should provide insight into the mechanisms by which neuropeptides mediate normal and disrupted circadian rhythms in human disease. Project Narrative Defects in circadian clocks have been implicated in a variety of clinical disorders. Communication between neural pacemakers and to their downstream targets is mediated by neuropeptides. We will elucidate the role of a circadian neuropeptide in synchronizing circadian clocks and communicating timing information in a simple animal model. Given the potential conservation with humans, this work should provide insight into the mechanisms by which neuropeptides mediate normal and disrupted circadian rhythms in human disease.