title: Transcriptional regulation via nuclear receptor crosstalk required for the Drosophila circadian clock.
abstract: Circadian clocks in large part rely on transcriptional feedback loops. At the core of the clock machinery, the transcriptional activators CLOCK/BMAL1 (in mammals) and CLOCK/CYCLE (CLK/CYC) (in Drosophila) drive the expression of the period (per) family genes. The PER-containing complexes inhibit the activity of CLOCK/BMAL1 or CLK/CYC, thereby forming a negative feedback loop [1]. In mammals, the ROR and REV-ERB family nuclear receptors add positive and negative transcriptional regulation to this core negative feedback loop to ensure the generation of robust circadian molecular oscillation [2]. Despite the overall similarities between mammalian and Drosophila clocks, whether comparable mechanisms via nuclear receptors are required for the Drosophila clock remains unknown. We show here that the nuclear receptor E75, the fly homolog of REV-ERB α and REV-ERB β, and the NR2E3 subfamily nuclear receptor UNF are components of the molecular clocks in the Drosophila pacemaker neurons. In vivo assays in conjunction with the in vitro experiments demonstrate that E75 and UNF bind to per regulatory sequences and act together to enhance the CLK/CYC-mediated transcription of the per gene, thereby completing the core transcriptional feedback loop necessary for the free-running clockwork. Our results identify a missing link in the Drosophila clock and highlight the significance of the transcriptional regulation via nuclear receptors in metazoan circadian clocks.
authors.affiliation: Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland; Department of Genetics and Evolution, Sciences III, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Edouard
authors.initials: E
authors.lastname: Jaumouillé
authors.affiliation: Department of Genetics and Evolution, Sciences III, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Pedro
authors.initials: P
authors.lastname: Machado Almeida
authors.affiliation: Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland.
authors.forename: Patrick
authors.initials: P
authors.lastname: Stähli
authors.affiliation: Department of Genetics and Evolution, Sciences III, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Rafael
authors.initials: R
authors.lastname: Koch
authors.affiliation: Department of Genetics and Evolution, Sciences III, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland; PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan. Electronic address: emi.nagoshi@unige.ch.
authors.forename: Emi
authors.initials: E
authors.lastname: Nagoshi
mesh_terms: D056930:ARNTL Transcription Factors / Q000378:metabolism; D000818:Animals; D056926:CLOCK Proteins / Q000378:metabolism; D057906:Circadian Clocks; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004330:Drosophila / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D019476:Insect Proteins / Q000378:metabolism*; D056950:Period Circadian Proteins / Q000378:metabolism*; D020239:Receptor Cross-Talk; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*
chemical_list: D056930:ARNTL Transcription Factors; C120526:Clk protein, Drosophila; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C087173:E75 protein, insect; C539176:Hr51 protein, Drosophila; D019476:Insect Proteins; C539040:PER protein, Drosophila; D056950:Period Circadian Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; C112805:cyc protein, Drosophila; D056926:CLOCK Proteins