title: PDF Signaling Is an Integral Part of the Drosophila Circadian Molecular Oscillator.
abstract: Circadian clocks generate 24-hr rhythms in physiology and behavior. Despite numerous studies, it is still uncertain how circadian rhythms emerge from their molecular and neural constituents. Here, we demonstrate a tight connection between the molecular and neuronal circadian networks. Using fluorescent transcriptional reporters in a Drosophila ex vivo brain culture system, we identified a reciprocal negative regulation between the master circadian regulator CLK and expression of pdf, the main circadian neuropeptide. We show that PDF feedback is required for maintaining normal oscillation pattern in CLK-driven transcription. Interestingly, we found that CLK and neuronal firing suppresses pdf transcription, likely through a common pathway involving the transcription factors DHR38 and SR, establishing a direct link between electric activity and the circadian system. In sum, our work provides evidence for the existence of an uncharacterized CLK-PDF feedback loop that tightly wraps together the molecular oscillator with the circadian neuronal network in Drosophila.
authors.affiliation: Biological Chemistry Department, Silberman Institute of Life Sciences, the Hebrew University, Jerusalem 91904, Israel.
authors.forename: Shaul
authors.initials: S
authors.lastname: Mezan
authors.affiliation: Institute of Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland.
authors.forename: Jean Daniel
authors.initials: JD
authors.lastname: Feuz
authors.affiliation: Institute of Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland.
authors.forename: Bart
authors.initials: B
authors.lastname: Deplancke
authors.affiliation: Biological Chemistry Department, Silberman Institute of Life Sciences, the Hebrew University, Jerusalem 91904, Israel. Electronic address: skadener@mail.huji.ac.il.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kadener
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000235:genetics; D056926:CLOCK Proteins / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology*; D005453:Fluorescence; D017930:Genes, Reporter; D008954:Models, Biological; D009415:Nerve Net / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: C120526:Clk protein, Drosophila; D029721:Drosophila Proteins; D009479:Neuropeptides; C113883:pdf protein, Drosophila; D056926:CLOCK Proteins
keywords: CLK; Drosophila; PDF; brain culture; circadian; transcriptional fluorescent reporters