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.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS059042-05
Application #
8280370
Study Section
Special Emphasis Panel (ZRG1-IFCN-A (04))
Program Officer
He, Janet
Project Start
2008-07-01
Project End
2013-09-30
Budget Start
2012-07-01
Budget End
2013-09-30
Support Year
5
Fiscal Year
2012
Total Cost
$323,706
Indirect Cost
$109,331
Name
Northwestern University at Chicago
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
160079455
City
Evanston
State
IL
Country
United States
Zip Code
60201
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Lim, Chunghun; Allada, Ravi (2013) Emerging roles for post-transcriptional regulation in circadian clocks. Nat Neurosci 16:1544-50
Lim, Chunghun; Allada, Ravi (2013) ATAXIN-2 activates PERIOD translation to sustain circadian rhythms in Drosophila. Science 340:875-9
Lim, Chunghun; Lee, Jongbin; Choi, Changtaek et al. (2011) The novel gene twenty-four defines a critical translational step in the Drosophila clock. Nature 470:399-403
Allada, Ravi; Chung, Brian Y (2010) Circadian organization of behavior and physiology in Drosophila. Annu Rev Physiol 72:605-24
Zhang, Luoying; Chung, Brian Y; Lear, Bridget C et al. (2010) DN1(p) circadian neurons coordinate acute light and PDF inputs to produce robust daily behavior in Drosophila. Curr Biol 20:591-9
Zhang, Luoying; Lear, Bridget C; Seluzicki, Adam et al. (2009) The CRYPTOCHROME photoreceptor gates PDF neuropeptide signaling to set circadian network hierarchy in Drosophila. Curr Biol 19:2050-5
Kilman, Valerie L; Allada, Ravi (2009) Genetic analysis of ectopic circadian clock induction in Drosophila. J Biol Rhythms 24:368-78
Lear, Bridget C; Zhang, Luoying; Allada, Ravi (2009) The neuropeptide PDF acts directly on evening pacemaker neurons to regulate multiple features of circadian behavior. PLoS Biol 7:e1000154
Allada, Ravi; Siegel, Jerome M (2008) Unearthing the phylogenetic roots of sleep. Curr Biol 18:R670-R679