Cycling in a circadian circuit

 描述（由申请人提供）：我们的总体目标是确定如何产生行为的昼夜节律。在这个项目的前期工作中，我们确定并表征了果蝇内源性生物钟的分子机制。我们还启动了研究，以确定从时钟中携带时间线索并通过大脑传输它们的机制。具体来说，我们确定了节律性休息所需的输出神经元：活动，并在解剖学上连接到中央时钟神经元。这些输出神经元包括背神经元1（DN1）组，其中包含一个时钟，以及大脑间部（PI）中的两个非时钟簇，这是一个相当于哺乳动物下丘脑的神经分泌细胞区域。调节静息活动的昼夜节律的两个PI簇分别分泌神经肽DH44和SIFamide。我们发现DH44是行为节律所必需的，但SIFamide的作用尚未确定。有趣的是，DN1也与已知的昼夜节律输出分子的功能或表达有关，如腹部狭窄和不成对。此外，我们的初步数据表明，另一种输出分子，神经纤维瘤病1（NF 1），需要在DN1休息：活动节奏。我们还发现，在DN1和DH44细胞中，神经活动以24小时节律循环。因此，我们已经开始将分子成分放置在我们确定的细胞基质中，并开发检测方法来监测节律信号通过网络的传输。我们假设中枢时钟细胞中产生的时间线索通过DN1传递，以驱动PI中的节律活动， 然后通过释放特定的神经肽来控制休息：活动节律。我们建议：（1）解决DN1中节律活动的重要性，并确定这种节律需要哪些时钟细胞和输出分子。(2)识别时钟细胞中驱动DH44细胞节律活动的上游成分，并确定DH44是否有节律地活动。(3)说明SIFamide在休息：活动节律中的作用，并确定与休息：活动节律相关的其他PI分子。这些研究有望为产生行为节律的分子网络和细胞回路提供全面的理解。鉴于已知的生物钟机制和分子从苍蝇到人类的保守性，这些研究可能与我们对人类节律的理解有关，这对正常行为和生理至关重要。这些研究还将为神经回路的维护和功能提供一般性见解，这些神经回路在几种神经系统疾病中受损。

 DESCRIPTION (provided by applicant): Our overall goal is to determine how circadian rhythms of behavior are generated. In previous work on this project we identified and characterized molecular mechanisms of the endogenous circadian clock in Drosophila. We also initiated studies to identify the mechanisms that carry time of day cues from the clock and transmit them through the brain. Specifically, we identified output neurons that are required for rhythmic rest:activity and connect anatomically to central clock neurons. These output neurons include the Dorsal Neuron 1 (DN1) group, which contains a clock, and two non-clock clusters in the pars intercerebralis (PI), a region of neurosecretory cells equivalent to the mammalian hypothalamus. The two PI clusters that regulate circadian rhythms of rest:activity secretes the neuropeptides DH44 and SIFamide respectively. We found that DH44 is required for behavioral rhythms, but a role for SIFamide has not been determined yet. Interestingly, the DN1s have also been associated with the function or expression of known circadian output molecules, narrow abdomen and unpaired. In addition, our preliminary data indicate that another output molecule, Neurofibromatosis 1 (NF1), is required in DN1s for rest:activity rhythms. We also find that neural activity cycles with a 24 hour rhythm in DN1 and DH44 cells. Thus, we have started to place molecular components in the cellular substrates we identified, and develop assays to monitor the transmission of rhythmic signals through the network. We hypothesize that time-of-day cues generated in central clock cells are transmitted through DN1s to drive rhythmic activity in the PI, which then controls rest:activity rhythms through release of specific neuropeptides. We propose to: (1) Address the significance of rhythmic activity in the DN1s and determine which clock cells and output molecules are required for this rhythm. (2) Identify the upstream components in clock cells that drive rhythmic activity in the DH44 cells, and determine if DH44 acts rhythmically. (3) Address a role for SIFamide in rest:activity rhythms and identify other PI molecules relevant for rest:activity rhythms. Together these studies are expected to provide a comprehensive understanding of the molecular network and cellular circuit that generates a behavioral rhythm. Given known conservation of clock mechanisms and molecules from flies to humans, these studies will likely be relevant for our understanding of human rhythms, which are critical for normal behavior and physiology. These studies will also provide general insight into the maintenance and function of neural circuits, which are impaired in several neurological disorders.