title: Pacemaker-neuron-dependent disturbance of the molecular clockwork by a Drosophila CLOCK mutant homologous to the mouse Clock mutation.
abstract: Circadian clocks are composed of transcriptional/translational feedback loops (TTFLs) at the cellular level. In Drosophila TTFLs, the transcription factor dCLOCK (dCLK)/CYCLE (CYC) activates clock target gene expression, which is repressed by the physical interaction with PERIOD (PER). Here, we show that amino acids (AA) 657-707 of dCLK, a region that is homologous to the mouse Clock exon 19-encoded region, is crucial for PER binding and E-box-dependent transactivation in S2 cells. Consistently, in transgenic flies expressing dCLK with an AA657-707 deletion in the Clock (Clk(out)) genetic background (p{dClk-Δ};Clk(out)), oscillation of core clock genes' mRNAs displayed diminished amplitude compared with control flies, and the highly abundant dCLKΔ657-707 showed significantly decreased binding to PER. Behaviorally, the p{dClk-Δ};Clk(out) flies exhibited arrhythmic locomotor behavior in the photic entrainment condition but showed anticipatory activities of temperature transition and improved free-running rhythms in the temperature entrainment condition. Surprisingly, p{dClk-Δ};Clk(out) flies showed pacemaker-neuron-dependent alterations in molecular rhythms; the abundance of dCLK target clock proteins was reduced in ventral lateral neurons (LNvs) but not in dorsal neurons (DNs) in both entrainment conditions. In p{dClk-Δ};Clk(out) flies, however, strong but delayed molecular oscillations in temperature cycle-sensitive pacemaker neurons, such as DN1s and DN2s, were correlated with delayed anticipatory activities of temperature transition. Taken together, our study reveals that the LNv molecular clockwork is more sensitive than the clockwork of DNs to dysregulation of dCLK by AA657-707 deletion. Therefore, we propose that the dCLK/CYC-controlled TTFL operates differently in subsets of pacemaker neurons, which may contribute to their specific functions.
authors.affiliation: Neuroscience Graduate Program, BK21 Plus Program, Department of Biomedical Sciences, Ajou University School of Medicine, Yeongtong-gu, Suwon, Kyunggi-do 16499, Republic of Korea; Department of Brain Science, Ajou University School of Medicine, Yeongtong-gu, Suwon, Kyunggi-do 16499, Republic of Korea;
authors.forename: Euna
authors.initials: E
authors.lastname: Lee
authors.affiliation: Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Yeongtong-gu, Suwon, Kyunggi-do 16499, Republic of Korea;
authors.forename: Eunjoo
authors.initials: E
authors.lastname: Cho
authors.affiliation: Neuroscience Graduate Program, BK21 Plus Program, Department of Biomedical Sciences, Ajou University School of Medicine, Yeongtong-gu, Suwon, Kyunggi-do 16499, Republic of Korea; Department of Brain Science, Ajou University School of Medicine, Yeongtong-gu, Suwon, Kyunggi-do 16499, Republic of Korea;
authors.forename: Doo Hyun
authors.initials: DH
authors.lastname: Kang
authors.affiliation: Department of Brain Science, Ajou University School of Medicine, Yeongtong-gu, Suwon, Kyunggi-do 16499, Republic of Korea;
authors.forename: Eun Hee
authors.initials: EH
authors.lastname: Jeong
authors.affiliation: Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030.
authors.forename: Seung-Hee
authors.initials: SH
authors.lastname: Yoo
authors.affiliation: Neuroscience Graduate Program, BK21 Plus Program, Department of Biomedical Sciences, Ajou University School of Medicine, Yeongtong-gu, Suwon, Kyunggi-do 16499, Republic of Korea; Department of Brain Science, Ajou University School of Medicine, Yeongtong-gu, Suwon, Kyunggi-do 16499, Republic of Korea; Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Yeongtong-gu, Suwon, Kyunggi-do 16499, Republic of Korea; ekim@ajou.ac.kr.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Kim
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D056926:CLOCK Proteins / Q000235:genetics* / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology; D004330:Drosophila; D029721:Drosophila Proteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D051379:Mice; D009154:Mutation; D009474:Neurons / Q000502:physiology*; D056950:Period Circadian Proteins / Q000378:metabolism; D013696:Temperature
chemical_list: C120526:Clk protein, Drosophila; D029721:Drosophila Proteins; D056950:Period Circadian Proteins; C096445:tim protein, Drosophila; D056926:CLOCK Proteins
keywords: CLOCK; TTFL; circadian rhythm; dorsal neuron; lateral neuron