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Sample records for clock genes period

  1. Finding Clocks in Genes: A Bayesian Approach to Estimate Periodicity

    PubMed Central

    Ren, Yan; Hong, Christian I.; Lim, Sookkyung; Song, Seongho

    2016-01-01

    Identification of rhythmic gene expression from metabolic cycles to circadian rhythms is crucial for understanding the gene regulatory networks and functions of these biological processes. Recently, two algorithms, JTK_CYCLE and ARSER, have been developed to estimate periodicity of rhythmic gene expression. JTK_CYCLE performs well for long or less noisy time series, while ARSER performs well for detecting a single rhythmic category. However, observing gene expression at high temporal resolution is not always feasible, and many scientists are interested in exploring both ultradian and circadian rhythmic categories simultaneously. In this paper, a new algorithm, named autoregressive Bayesian spectral regression (ABSR), is proposed. It estimates the period of time-course experimental data and classifies gene expression profiles into multiple rhythmic categories simultaneously. Through the simulation studies, it is shown that ABSR substantially improves the accuracy of periodicity estimation and clustering of rhythmic categories as compared to JTK_CYCLE and ARSER for the data with low temporal resolution. Moreover, ABSR is insensitive to rhythmic patterns. This new scheme is applied to existing time-course mouse liver data to estimate period of rhythms and classify the genes into ultradian, circadian, and arrhythmic categories. It is observed that 49.2% of the circadian profiles detected by JTK_CYCLE with 1-hour resolution are also detected by ABSR with only 4-hour resolution. PMID:27340654

  2. The clock gene Period1 regulates innate routine behaviour in mice

    PubMed Central

    Bechstein, Philipp; Rehbach, Nils-Jörn; Yuhasingham, Gowzekan; Schürmann, Christoph; Göpfert, Melanie; Kössl, Manfred; Maronde, Erik

    2014-01-01

    Laboratory mice are well capable of performing innate routine behaviour programmes necessary for courtship, nest-building and exploratory activities although housed for decades in animal facilities. We found that in mice inactivation of the clock gene Period1 profoundly changes innate routine behaviour programmes like those necessary for courtship, nest building, exploration and learning. These results in wild-type and Period1 mutant mice, together with earlier findings on courtship behaviour in wild-type and period-mutant Drosophila melanogaster, suggest a conserved role of Period-genes on innate routine behaviour. Additionally, both per-mutant flies and Period1-mutant mice display spatial learning and memory deficits. The profound influence of Period1 on routine behaviour programmes in mice, including female partner choice, may be independent of its function as a circadian clock gene, since Period1-deficient mice display normal circadian behaviour. PMID:24598427

  3. Twist1 Is a TNF-Inducible Inhibitor of Clock Mediated Activation of Period Genes

    PubMed Central

    Meier, Daniel; Lopez, Martin; Franken, Paul; Fontana, Adriano

    2015-01-01

    Background Activation of the immune system affects the circadian clock. Tumor necrosis factor (TNF) and Interleukin (IL)-1β inhibit the expression of clock genes including Period (Per) genes and the PAR-bZip clock-controlled gene D-site albumin promoter-binding protein (Dbp). These effects are due to cytokine-induced interference of E-box mediated transcription of clock genes. In the present study we have assessed the two E-box binding transcriptional regulators Twist1 and Twist2 for their role in cytokine induced inhibition of clock genes. Methods The expression of the clock genes Per1, Per2, Per3 and of Dbp was assessed in NIH-3T3 mouse fibroblasts and the mouse hippocampal neuronal cell line HT22. Cells were treated for 4h with TNF and IL-1β. The functional role of Twist1 and Twist2 was assessed by siRNAs against the Twist genes and by overexpression of TWIST proteins. In luciferase (luc) assays NIH-3T3 cells were transfected with reporter gene constructs, which contain a 3xPer1 E-box or a Dbp E-box. Quantitative chromatin immunoprecipitation (ChIP) was performed using antibodies to TWIST1 and CLOCK, and the E-box consensus sequences of Dbp (CATGTG) and Per1 E-box (CACGTG). Results We report here that siRNA against Twist1 protects NIH-3T3 cells and HT22 cells from down-regulation of Period and Dbp by TNF and IL-1β. Overexpression of Twist1, but not of Twist2, mimics the effect of the cytokines. TNF down-regulates the activation of Per1-3xE-box-luc, the effect being prevented by siRNA against Twist1. Overexpression of Twist1, but not of Twist2, inhibits Per1-3xE-box-luc or Dbp-E-Box-luc activity. ChIP experiments show TWIST1 induction by TNF to compete with CLOCK binding to the E-box of Period genes and Dbp. Conclusion Twist1 plays a pivotal role in the TNF mediated suppression of E-box dependent transactivation of Period genes and Dbp. Thereby Twist1 may provide a link between the immune system and the circadian timing system. PMID:26361389

  4. The circadian clock gene period extends healthspan in aging Drosophila melanogaster

    PubMed Central

    Krishnan, Natraj; Kretzschmar, Doris; Rakshit, Kuntol; Chow, Eileen; Giebultowicz, Jadwiga M.

    2009-01-01

    There is increasing evidence that aging is affected by biological (circadian) clocks - the internal mechanisms that coordinate daily changes in gene expression, physiological functions and behavior with external day/night cycles. Recent data suggest that disruption of the mammalian circadian clock results in accelerated aging and increased age-related pathologies such as cancer; however, the links between loss of daily rhythms and aging are not understood. We sought to determine whether disruption of the circadian clock affects lifespan and healthspan in the model organism Drosophila melanogaster. We examined effects of a null mutation in the circadian clock gene period (per01) on the fly healthspan by challenging aging flies with short-term oxidative stress (24h hyperoxia) and investigating their response in terms of mortality hazard, levels of oxidative damage, and functional senescence. Exposure to 24h hyperoxia during middle age significantly shortened the life expectancy in per01 but not in control flies. This homeostatic challenge also led to significantly higher accumulation of oxidative damage in per01 flies compared to controls. In addition, aging per01 flies showed accelerated functional decline, such as lower climbing ability and increased neuronal degeneration compared to age-matched controls. Together, these data suggest that impaired stress defense pathways may contribute to accelerated aging in the per mutant. In addition, we show that the expression of per gene declines in old wild type flies, suggesting that the circadian regulatory network becomes impaired with age. PMID:20157575

  5. The Circadian Clock Gene Period1 Connects the Molecular Clock to Neural Activity in the Suprachiasmatic Nucleus

    PubMed Central

    Block, Gene D.; Colwell, Christopher S.

    2015-01-01

    The neural activity patterns of suprachiasmatic nucleus (SCN) neurons are dynamically regulated throughout the circadian cycle with highest levels of spontaneous action potentials during the day. These rhythms in electrical activity are critical for the function of the circadian timing system and yet the mechanisms by which the molecular clockwork drives changes in the membrane are not well understood. In this study, we sought to examine how the clock gene Period1 (Per1) regulates the electrical activity in the mouse SCN by transiently and selectively decreasing levels of PER1 through use of an antisense oligodeoxynucleotide. We found that this treatment effectively reduced SCN neural activity. Direct current injection to restore the normal membrane potential partially, but not completely, returned firing rate to normal levels. The antisense treatment also reduced baseline [Ca2+]i levels as measured by Fura2 imaging technique. Whole cell patch clamp recording techniques were used to examine which specific potassium currents were altered by the treatment. These recordings revealed that the large conductance [Ca2+]i-activated potassium currents were reduced in antisense-treated neurons and that blocking this current mimicked the effects of the anti-sense on SCN firing rate. These results indicate that the circadian clock gene Per1 alters firing rate in SCN neurons and raise the possibility that the large conductance [Ca2+]i-activated channel is one of the targets. PMID:26553726

  6. Glucocorticoid Ultradian Rhythmicity Directs Cyclical Gene Pulsing of the Clock Gene Period 1 in Rat Hippocampus

    PubMed Central

    McKenna, M. A.; Pooley, J. R.; Kershaw, Y. M.; Meijer, O. C.; de Kloet, E. R.; Lightman, S. L.

    2016-01-01

    In vivo glucocorticoid (GC) secretion exhibits a distinctive ultradian rhythmicity. The lipophilic hormone can rapidly diffuse into cells, although only the pulse peak is of sufficient amplitude to activate the low affinity glucocorticoid receptor (GR). Discrete pulses readily access brain regions such as the hippocampus where GR expression is enriched and known to regulate neuronal function, including memory and learning processes. In the present study, we have tested the hypothesis that GR brain targets are responsive to ultradian GC rhythmicity. We have used adrenalectomised rats replaced with pulses of corticosterone to determine the transcriptional effects of ultradian pulses in the hippocampus. Confocal microscopy confirmed that each GC pulse results in transient GR nuclear localisation in hippocampal CA1 neurones. Concomitant GR activation and DNA binding was demonstrated by synthetic glucocorticoid response element oligonucleotide binding, and verified for the Clock gene Period 1 promoter region by chromatin immunoprecipitation assays. Strikingly each GC pulse induced a ‘burst’ of transcription of Period 1 measured by heterogeneous nuclear RNA quantitative polymerase chain reaction. The net effect of pulsatile GC exposure on accumulation of the mature transcript was also assessed, revealing a plateau of mRNA levels throughout the time course of pulsatile exposure, indicating the pulse timing works optimally for steady state Per1 expression. The plateau dropped to baseline within 120 min of the final pulse, indicating a relatively short half-life for hippocampal Per1. The significance of this strict temporal control is that any perturbation to the pulse frequency or duration would have rapid quantitative effects on the levels of Per1. This in turn could affect hippocampal function, especially circadian related memory and learning processes. PMID:20649850

  7. Melanopsin resets circadian rhythms in cells by inducing clock gene Period1

    NASA Astrophysics Data System (ADS)

    Yamashita, Shuhei; Uehara, Tomoe; Matsuo, Minako; Kikuchi, Yo; Numano, Rika

    2014-02-01

    The biochemical, physiological and behavioral processes are under the control of internal clocks with the period of approximately 24 hr, circadian rhythms. The expression of clock gene Period1 (Per1) oscillates autonomously in cells and is induced immediately after a light pulse. Per1 is an indispensable member of the central clock system to maintain the autonomous oscillator and synchronize environmental light cycle. Per1 expression could be detected by Per1∷luc and Per1∷GFP plasmid DNA in which firefly luciferase and Green Fluorescence Protein were rhythmically expressed under the control of the mouse Per1 promoter in order to monitor mammalian circadian rhythms. Membrane protein, MELANOPSIN is activated by blue light in the morning on the retina and lead to signals transduction to induce Per1 expression and to reset the phase of circadian rhythms. In this report Per1 induction was measured by reporter signal assay in Per1∷luc and Per1∷GFP fibroblast cell at the input process of circadian rhythms. To the result all process to reset the rhythms by Melanopsin is completed in single cell like in the retina projected to the central clock in the brain. Moreover, the phase of circadian rhythm in Per1∷luc cells is synchronized by photo-activated Melanopsin, because the definite peak of luciferase activity in one dish was found one day after light illumination. That is an available means that physiological circadian rhythms could be real-time monitor as calculable reporter (bioluminescent and fluorescent) chronological signal in both single and groups of cells.

  8. Case-control study of the PERIOD3 clock gene length polymorphism and colorectal adenoma formation.

    PubMed

    Alexander, Melannie; Burch, James B; Steck, Susan E; Chen, Chin-Fu; Hurley, Thomas G; Cavicchia, Philip; Ray, Meredith; Shivappa, Nitin; Guess, Jaclyn; Zhang, Hongmei; Youngstedt, Shawn D; Creek, Kim E; Lloyd, Stephen; Yang, Xiaoming; Hébert, James R

    2015-02-01

    Clock genes are expressed in a self-perpetuating, circadian pattern in virtually every tissue including the human gastrointestinal tract. They coordinate cellular processes critical for tumor development, including cell proliferation, DNA damage response and apoptosis. Circadian rhythm disturbances have been associated with an increased risk for colon cancer and other cancers. This mechanism has not been elucidated, yet may involve dysregulation of the 'period' (PER) clock genes, which have tumor suppressor properties. A variable number tandem repeat (VNTR) in the PERIOD3 (PER3) gene has been associated with sleep disorders, differences in diurnal hormone secretion, and increased premenopausal breast cancer risk. Susceptibility related to PER3 has not been examined in conjunction with adenomatous polyps. This exploratory case-control study was the first to test the hypothesis that the 5-repeat PER3 VNTR sequence is associated with increased odds of adenoma formation. Information on demographics, medical history, occupation and lifestyle was collected prior to colonoscopy. Cases (n=49) were individuals with at least one histopathologically confirmed adenoma. Controls (n=97) included patients with normal findings or hyperplastic polyps not requiring enhanced surveillance. Unconditional multiple logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs), after adjusting for potential confounding. Adenomas were detected in 34% of participants. Cases were more likely to possess the 5-repeat PER3 genotype relative to controls (4/5 OR, 2.1; 95% CI, 0.9-4.8; 5/5 OR, 5.1; 95% CI, 1.4-18.1; 4/5+5/5 OR, 2.5; 95% CI, 1.7-5.4). Examination of the Oncomine microarray database indicated lower PERIOD gene expression in adenomas relative to adjacent normal tissue. Results suggest a need for follow-up in a larger sample. PMID:25501848

  9. Light modulation of human sleep depends on a polymorphism in the clock gene Period3.

    PubMed

    Chellappa, Sarah L; Viola, Antoine U; Schmidt, Christina; Bachmann, Valérie; Gabel, Virginie; Maire, Micheline; Reichert, Carolin F; Valomon, Amandine; Landolt, Hans-Peter; Cajochen, Christian

    2014-09-01

    Non-image-forming (NIF) responses to light powerfully modulate human physiology. However, it remains scarcely understood how NIF responses to light modulate human sleep and its EEG hallmarks, and if there are differences across individuals. Here we investigated NIF responses to light on sleep in individuals genotyped for the PERIOD3 (PER3) variable-number tandem-repeat (VNTR) polymorphism. Eighteen healthy young men (20-28 years; mean ± SEM: 25.9 ± 1.2) homozygous for the PER3 polymorphism were matched by age, body-mass index, and ethnicity. The study protocol comprised a balanced cross-over design during the winter, during which participants were exposed to either light of 40 lx at 6,500 K (blue-enriched) or light at 2,500 K (non-blue enriched), during 2h in the evening. Compared to light at 2,500 K, light at 6,500 K induced a significant increase in all-night NREM sleep slow-wave activity (SWA: 1.0-4.5 Hz) in the occipital cortex for PER3(5/5) individuals, but not for PER3(4/4) volunteers. Dynamics of SWA across sleep cycles revealed increased occipital NREM sleep SWA for virtually all sleep episode only for PER3(5/5) individuals. Furthermore, they experienced light at 6,500 K as significantly brighter. Intriguingly, this subjective perception of brightness significantly predicted their increased occipital SWA throughout the sleep episode. Our data indicate that humans homozygous for the PER3(5/5) allele are more sensitive to NIF light effects, as indexed by specific changes in sleep EEG activity. Ultimately, individual differences in NIF light responses on sleep may depend on a clock gene polymorphism involved in sleep-wake regulation. PMID:24893318

  10. Expression of the circadian clock gene Period2 in the hippocampus: possible implications for synaptic plasticity and learned behaviour

    PubMed Central

    Wang, Louisa M-C; Dragich, Joanna M; Kudo, Takashi; Odom, Irene H; Welsh, David K; O'Dell, Thomas J; Colwell, Christopher S

    2009-01-01

    Genes responsible for generating circadian oscillations are expressed in a variety of brain regions not typically associated with circadian timing. The functions of this clock gene expression are largely unknown, and in the present study we sought to explore the role of the Per2 (Period 2) gene in hippocampal physiology and learned behaviour. We found that PER2 protein is highly expressed in hippocampal pyramidal cell layers and that the expression of both protein and mRNA varies with a circadian rhythm. The peaks of these rhythms occur in the late night or early morning and are almost 180° out-of-phase with the expression rhythms measured from the suprachiasmatic nucleus of the same animals. The rhythms in Per2 expression are autonomous as they are present in isolated hippocampal slices maintained in culture. Physiologically, Per2-mutant mice exhibit abnormal long-term potentiation. The underlying mechanism is suggested by the finding that levels of phosphorylated cAMP-response-element-binding protein, but not phosphorylated extracellular-signal-regulated kinase, are reduced in hippocampal tissue from mutant mice. Finally, Per2-mutant mice exhibit deficits in the recall of trace, but not cued, fear conditioning. Taken together, these results provide evidence that hippocampal cells contain an autonomous circadian clock. Furthermore, the clock gene Per2 may play a role in the regulation of long-term potentiation and in the recall of some forms of learned behaviour. PMID:19570032

  11. The clock gene period of the housefly, Musca domestica, rescues behavioral rhythmicity in Drosophila melanogaster. Evidence for intermolecular coevolution?

    PubMed Central

    Piccin, A; Couchman, M; Clayton, J D; Chalmers, D; Costa, R; Kyriacou, C P

    2000-01-01

    In Drosophila, the clock gene period (per), is an integral component of the circadian clock and acts via a negative autoregulatory feedback loop. Comparative analyses of per genes in insects and mammals have revealed that they may function in similar ways. However in the giant silkmoth, Antheraea pernyi, per expression and that of the partner gene, tim, is not consistent with the negative feedback role. As an initial step in developing an alternative dipteran model to Drosophila, we have identified the per orthologue in the housefly, Musca domestica. The Musca per sequence highlights a pattern of conservation and divergence similar to other insect per genes. The PAS dimerization domain shows an unexpected phylogenetic relationship in comparison with the corresponding region of other Drosophila species, and this appears to correlate with a functional assay of the Musca per transgene in Drosophila melanogaster per-mutant hosts. A simple hypothesis based on the coevolution of the PERIOD and TIMELESS proteins with respect to the PER PAS domain can explain the behavioral data gathered from transformants. PMID:10655226

  12. Expression of clock genes period and timeless in the central nervous system of the Mediterranean flour moth, Ephestia kuehniella.

    PubMed

    Kobelková, Alena; Závodská, Radka; Sauman, Ivo; Bazalová, Olga; Dolezel, David

    2015-04-01

    Homologous circadian genes are found in all insect clocks, but their contribution to species-specific circadian timing systems differs. The aim of this study was to extend research within Lepidoptera to gain a better understanding of the molecular mechanism underlying circadian clock plasticity and evolution. The Mediterranean flour moth, Ephestia kuehniella (Pyralidae), represents a phylogenetically ancestral lepidopteran species. We have identified circadian rhythms in egg hatching, adult emergence, and adult locomotor activity. Cloning full-length complementary DNAs and further characterization confirmed one copy of period and timeless genes in both sexes. Both per and tim transcripts oscillate in their abundance in E. kuehniella heads under light-dark conditions. PER-like immunoreactivity (PER-lir) was observed in nuclei and cytoplasm of most neurons in the central brain, the ventral part of subesophageal complex, the neurohemal organs, the optic lobes, and eyes. PER-lir in photoreceptor nuclei oscillated during the day with maximal intensity in the light phase of the photoperiodic regime and lack of a signal in the middle of the dark phase. Expression patterns of per and tim messenger RNAs (mRNAs) were revealed in the identical location as the PER-lir was detected. In the photoreceptors, a daily rhythm in the intensity of expression of both per mRNA and tim mRNA was found. These findings suggest E. kuehniella as a potential lepidopteran model for circadian studies. PMID:25637625

  13. A Novel Pathway for Sensory-Mediated Arousal Involves Splicing of an Intron in the period Clock Gene

    PubMed Central

    Cao, Weihuan; Edery, Isaac

    2015-01-01

    Study Objectives: D. melanogaster is an excellent animal model to study how the circadian (≅ 24-h) timing system and sleep regulate daily wake-sleep cycles. Splicing of a temperature-sensitive 3'-terminal intron (termed dmpi8) from the circadian clock gene period (per) regulates the distribution of daily activity in Drosophila. The role of dmpi8 splicing on daily behavior was further evaluated by analyzing sleep. Design: Transgenic flies of the same genetic background but expressing either a wild-type recombinant per gene or one where the efficiency of dmpi8 splicing was increased were exposed to different temperatures in daily light-dark cycles and sleep parameters measured. In addition, transgenic flies were briefly exposed to a variety of sensory-mediated stimuli to measure arousal responses. Results: Surprisingly, we show that the effect of dmpi8 splicing on daytime activity levels does not involve a circadian role for per but is linked to adjustments in sensory-dependent arousal and sleep behavior. Genetically altered flies with high dmpi8 splicing efficiency remain aroused longer following short treatments with light and non-photic cues such as mechanical stimulation. Conclusions: We propose that the thermal regulation of dmpi8 splicing acts as a temperature-calibrated rheostat in a novel arousal mechanism, so that on warm days the inefficient splicing of the dmpi8 intron triggers an increase in quiescence by decreasing sensory-mediated arousal, thus ensuring flies minimize being active during the hot midday sun despite the presence of light in the environment, which is usually a strong arousal cue for diurnal animals. Citation: Cao W, Edery I. A novel pathway for sensory-mediated arousal involves splicing of an intron in the period clock gene. SLEEP 2015;38(1):41–51. PMID:25325457

  14. Analysis of the genetic structure of allopatric populations of Lutzomyia umbratilis using the period clock gene.

    PubMed

    de Souza Freitas, Moises Thiago; Ríos-Velasquez, Claudia Maria; da Silva, Lidiane Gomes; Costa, César Raimundo Lima; Marcelino, Abigail; Leal-Balbino, Tereza Cristina; Balbino, Valdir de Queiroz; Pessoa, Felipe Arley Costa

    2016-02-01

    In South America, Lutzomyia umbratilis is the main vector of Leishmania guyanensis, one of the species involved in the transmission of American tegumentary leishmaniasis. In Brazil, L. umbratilis has been recorded in the Amazon region, and an isolated population has been identified in the state of Pernambuco, Northeastern region. This study assessed the phylogeographic structure of three allopatric Brazilian populations of L. umbratilis. Samples of L. umbratilis were collected from Rio Preto da Eva (north of the Amazon River, Amazonas), from Manacapuru (south of the Amazon River), and from the isolated population in Recife, Pernambuco state. These samples were processed to obtain sequences of the period gene. Phylogenetic analysis revealed the presence of two distinct monophyletic clades: one clade comprised of the Recife and Rio Preto da Eva samples, and one clade comprised of the Manacapuru samples. Comparing the Manacapuru population with the Recife and Rio Preto da Eva populations revealed high indices of interpopulational divergence. Phylogenetic analysis indicated that geographical distance and environmental differences have not modified the ancestral relationship shared by the Recife and Rio Preto da Eva populations. Genetic similarities suggest that, in evolutionary terms, these populations are more closely related to each other than to the Manacapuru population. These results confirm the existence of an L. umbratilis species complex composed of at least two incipient species. PMID:26655040

  15. Temperature cycle amplitude alters the adult eclosion time and expression pattern of the circadian clock gene period in the onion fly.

    PubMed

    Miyazaki, Yosuke; Watari, Yasuhiko; Tanaka, Kazuhiro; Goto, Shin G

    2016-03-01

    Soil temperature cycles are considered to play an important role in the entrainment of circadian clocks of underground insects. However, because of the low conductivity of soil, temperature cycles are gradually dampened and the phase of the temperature cycle is delayed with increasing soil depth. The onion fly, Delia antiqua, pupates at various soil depths, and its eclosion is timed by a circadian clock. This fly is able to compensate for the depth-dependent phase delay of temperature change by advancing the eclosion time with decreasing amplitude of the temperature cycle. Therefore, pupae can eclose at the appropriate time irrespective of their location at any depth. However, the mechanism that regulates eclosion time in response to temperature amplitude is still unknown. To understand whether this mechanism involves the circadian clock or further downstream physiological processes, we examined the expression patterns of period (per), a circadian clock gene, of D. antiqua under temperature cycles that were square wave cycles of 12-h warm phase (W) and 12-h cool phase (C) with the temperature difference of 8 °C (WC 29:21 °C) and 1 °C (WC 25.5:24.5 °C). The phase of oscillation in per expression was found to commence 3.5h earlier under WC 25.5:24.5 °C as compared to WC 29:21 °C. This difference was in close agreement with the eclosion time difference between the two temperature cycles, suggesting that the mechanism that responds to the temperature amplitude involves the circadian clock. PMID:26776097

  16. Clock Genes Show Circadian Rhythms in Salivary Glands

    PubMed Central

    Zheng, L.; Seon, Y.J.; McHugh, J.; Papagerakis, S.; Papagerakis, P.

    2012-01-01

    Circadian rhythms are endogenous self-sustained oscillations with 24-hour periods that regulate diverse physiological and metabolic processes through complex gene regulation by “clock” transcription factors. The oral cavity is bathed by saliva, and its amount and content are modified within regular daily intervals. The clock mechanisms that control salivary production remain unclear. Our objective was to evaluate the expression and periodicity of clock genes in salivary glands. Real-time quantitative RT-PCR, in situ hybridization, and immunohistochemistry were performed to show circadian mRNA and protein expression and localization of key clock genes (Bmal1, Clock, Per1, and Per2), ion and aqua channel genes (Ae2a, Car2, and Aqp5), and salivary gland markers. Clock gene mRNAs and clock proteins were found differentially expressed in the serous acini and duct cells of all major salivary glands. The expression levels of clock genes and Aqp5 showed regular oscillatory patterns under both light/dark and complete-dark conditions. Bmla1 overexpression resulted in increased Aqp5 expression levels. Analysis of our data suggests that salivary glands have a peripheral clock mechanism that functions both in normal light/dark conditions and in the absence of light. This finding may increase our understanding of the control mechanisms of salivary content and flow. PMID:22699207

  17. Case-Control Study of Breast Cancer in India: Role of PERIOD3 Clock Gene Length Polymorphism and Chronotype

    PubMed Central

    Wirth, Michael D.; Burch, James B.; Hébert, James R.; Kowtal, Pradnya; Kapoor, Aparna; Steck, Susan E.; Hurley, Thomas G.; Gupta, Prakash C.; Pednekar, Mangesh S.; Youngstedt, Shawn D.; Zhang, Hongmei; Sarin, Rajiv

    2014-01-01

    Background This study examined a PERIOD3 (PER3) gene variable number tandem repeat polymorphism and chronotype as potential BrCA risk factors among Indian women. Methods This case-control study included sporadic, histologically confirmed BrCA cases (n=255) and controls (n=249) from India with data collection from 2010–2012. Results Women with the 4/5 or 5/5 PER3 genotype had a non-statistically significant 33% increased odds of BrCA. BrCA cases were more likely to have a morning (OR=2.43, 95% CI=1.23–4.81) or evening (OR=2.55, 95% CI=1.19–5.47) chronotype. Conclusions Findings are consistent with the possibility that extremes in chronotype may elicit circadian desynchronization, resulting in adverse health outcomes. PMID:24903750

  18. microRNA modulation of circadian clock period and entrainment

    PubMed Central

    Cheng, Hai-Ying M.; Papp, Joseph W.; Varlamova, Olga; Dziema, Heather; Russell, Brandon; Curfman, John P.; Nakazawa, Takanobu; Shimizu, Kimiko; Okamura, Hitoshi; Impey, Soren; Obrietan, Karl

    2007-01-01

    microRNAs (miRNAs) are a class of small, non-coding, RNAs that regulate the stability or translation of mRNA transcripts. Although recent work has implicated miRNAs in development and in disease, the expression and function of miRNAs in the adult mammalian nervous system has not been extensively characterized. Here, we examine the role of two brain-specific miRNAs, miR-219 and miR-132, in modulating the circadian clock located in the suprachiasmatic nucleus. miR-219 is a target of the CLOCK/BMAL1 complex, exhibits robust circadian rhythms of expression and the in vivo knockdown of miR-219 lengthens the circadian period. miR-132 is induced by photic entrainment cues via a MAPK/CREB-dependent mechanism, modulates clock gene expression, and attenuates the entraining effects of light. Collectively, these data reveal miRNAs as clock- and light-regulated genes and provide a mechanistic examination of their roles as effectors of pacemaker activity and entrainment. PMID:17553428

  19. A Role for the PERIOD:PERIOD Homodimer in the Drosophila Circadian Clock

    PubMed Central

    Wolf, Eva; Stanewsky, Ralf

    2009-01-01

    Circadian clocks in eukaryotes rely on transcriptional feedback loops, in which clock genes repress their own transcription resulting in molecular oscillations with a period of ∼24 h. In Drosophila, the clock proteins Period (PER) and Timeless (TIM) operate in such a feedback loop, whereby they first accumulate in the cytoplasm of clock cells as a heterodimer. Nuclear translocation of the complex or the individual PER and TIM proteins is followed by repression of per and tim transcription, whereby PER seems to act as the prime repressor. We found that in addition to PER:TIM complexes, functional PER:PER homodimers exist in flies. Specific disruption of PER homodimers results in drastically impaired behavioral and molecular rhythmicity, pointing the biological importance of this clock protein complex. Analysis of PER subcellular distribution and repressor competence in the PER dimer mutant revealed defects in PER nuclear translocation and a disruption of rhythmic period transcription. The striking similarity of these phenotypes with that of reduced CKII activity suggests that the formation or function of the PER dimer is closely linked to this kinase. Our results confirm a previous structural model for PER and provide strong evidence that PER homodimers are important for circadian clock function. PMID:19402744

  20. Circadian expression of clock and putative clock-controlled genes in skeletal muscle of the zebrafish.

    PubMed

    Amaral, Ian P G; Johnston, Ian A

    2012-01-01

    To identify circadian patterns of gene expression in skeletal muscle, adult male zebrafish were acclimated for 2 wk to a 12:12-h light-dark photoperiod and then exposed to continuous darkness for 86 h with ad libitum feeding. The increase in gut food content associated with the subjective light period was much diminished by the third cycle, enabling feeding and circadian rhythms to be distinguished. Expression of zebrafish paralogs of mammalian transcriptional activators of the circadian mechanism (bmal1, clock1, and rora) followed a rhythmic pattern with a ∼24-h periodicity. Peak expression of rora paralogs occurred at the beginning of the subjective light period [Zeitgeber time (ZT)07 and ZT02 for roraa and rorab], whereas the highest expression of bmal1 and clock paralogs occurred 12 h later (ZT13-15 and ZT16 for bmal and clock paralogs). Expression of the transcriptional repressors cry1a, per1a/1b, per2, per3, nr1d2a/2b, and nr1d1 also followed a circadian pattern with peak expression at ZT0-02. Expression of the two paralogs of cry2 occurred in phase with clock1a/1b. Duplicated genes had a high correlation of expression except for paralogs of clock1, nr1d2, and per1, with cry1b showing no circadian pattern. The highest expression difference was 9.2-fold for the activator bmal1b and 51.7-fold for the repressor per1a. Out of 32 candidate clock-controlled genes, only myf6, igfbp3, igfbp5b, and hsf2 showed circadian expression patterns. Igfbp3, igfbp5b, and myf6 were expressed in phase with clock1a/1b and had an average of twofold change in expression from peak to trough, whereas hsf2 transcripts were expressed in phase with cry1a and had a 7.2-fold-change in expression. The changes in expression of clock and clock-controlled genes observed during continuous darkness were also observed at similar ZTs in fish exposed to a normal photoperiod in a separate control experiment. The role of circadian clocks in regulating muscle maintenance and growth are discussed

  1. Clock genes, pancreatic function, and diabetes.

    PubMed

    Vieira, Elaine; Burris, Thomas P; Quesada, Ivan

    2014-12-01

    Circadian physiology is responsible for the temporal regulation of metabolism to optimize energy homeostasis throughout the day. Disturbances in the light/dark cycle, sleep/wake schedule, or feeding/activity behavior can affect the circadian function of the clocks located in the brain and peripheral tissues. These alterations have been associated with impaired glucose tolerance and type 2 diabetes. Animal models with molecular manipulation of clock genes and genetic studies in humans also support these links. It has been demonstrated that the endocrine pancreas has an intrinsic self-sustained clock, and recent studies have revealed an important role of clock genes in pancreatic β cells, glucose homeostasis, and diabetes. PMID:25457619

  2. Clock gene variation in Tachycineta swallows

    PubMed Central

    Dor, Roi; Cooper, Caren B; Lovette, Irby J; Massoni, Viviana; Bulit, Flor; Liljesthrom, Marcela; Winkler, David W

    2012-01-01

    Many animals use photoperiod cues to synchronize reproduction with environmental conditions and thereby improve their reproductive success. The circadian clock, which creates endogenous behavioral and physiological rhythms typically entrained to photoperiod, is well characterized at the molecular level. Recent work provided evidence for an association between Clock poly-Q length polymorphism and latitude and, within a population, an association with the date of laying and the length of the incubation period. Despite relatively high overall breeding synchrony, the timing of clutch initiation has a large impact on the fitness of swallows in the genus Tachycineta. We compared length polymorphism in the Clock poly-Q region among five populations from five different Tachycineta species that breed across a hemisphere-wide latitudinal gradient (Fig. 1). Clock poly-Q variation was not associated with latitude; however, there was an association between Clock poly-Q allele diversity and the degree of clutch size decline within breeding seasons. We did not find evidence for an association between Clock poly-Q variation and date of clutch initiation in for any of the five Tachycineta species, nor did we found a relationship between incubation duration and Clock genotype. Thus, there is no general association between latitude, breeding phenology, and Clock polymorphism in this clade of closely related birds. Figure 1 Photos of Tachycineta swallows that were used in this study: A) T. bicolor from Ithaca, New York, B) T. leucorrhoa from Chascomús, Argentina, C) T. albilinea from Hill Bank, Belize, D) T. meyeni from Puerto Varas, Chile, and E) T. thalassina from Mono Lake, California, Photographers: B: Valentina Ferretti; A, C-E: David Winkler. PMID:22408729

  3. Interfering with Wnt signalling alters the periodicity of the segmentation clock

    PubMed Central

    Gibb, Sarah; Zagorska, Anna; Melton, Kristin; Tenin, Gennady; Vacca, Irene; Trainor, Paul; Maroto, Miguel; Dale, J. Kim

    2009-01-01

    Somites are embryonic precursors of the ribs, vertebrae and certain dermis tissue. Somite formation is a periodic process regulated by a molecular clock which drives cyclic expression of a number of clock genes in the presomitic mesoderm. To date the mechanism regulating the period of clock gene oscillations is unknown. Here we show that chick homologues of the Wnt pathway genes that oscillate in mouse do not cycle across the chick presomitic mesoderm. Strikingly we find that modifying Wnt signalling changes the period of Notch driven oscillations in both mouse and chick but these oscillations continue. We propose that the Wnt pathway is a conserved mechanism that is involved in regulating the period of cyclic gene oscillations in the presomitic mesoderm. PMID:19272372

  4. Body weight, metabolism and clock genes

    PubMed Central

    2010-01-01

    Biological rhythms are present in the lives of almost all organisms ranging from plants to more evolved creatures. These oscillations allow the anticipation of many physiological and behavioral mechanisms thus enabling coordination of rhythms in a timely manner, adaption to environmental changes and more efficient organization of the cellular processes responsible for survival of both the individual and the species. Many components of energy homeostasis exhibit circadian rhythms, which are regulated by central (suprachiasmatic nucleus) and peripheral (located in other tissues) circadian clocks. Adipocyte plays an important role in the regulation of energy homeostasis, the signaling of satiety and cellular differentiation and proliferation. Also, the adipocyte circadian clock is probably involved in the control of many of these functions. Thus, circadian clocks are implicated in the control of energy balance, feeding behavior and consequently in the regulation of body weight. In this regard, alterations in clock genes and rhythms can interfere with the complex mechanism of metabolic and hormonal anticipation, contributing to multifactorial diseases such as obesity and diabetes. The aim of this review was to define circadian clocks by describing their functioning and role in the whole body and in adipocyte metabolism, as well as their influence on body weight control and the development of obesity. PMID:20712885

  5. Body weight, metabolism and clock genes.

    PubMed

    Zanquetta, Melissa M; Corrêa-Giannella, Maria Lúcia; Monteiro, Maria Beatriz; Villares, Sandra Mf

    2010-01-01

    Biological rhythms are present in the lives of almost all organisms ranging from plants to more evolved creatures. These oscillations allow the anticipation of many physiological and behavioral mechanisms thus enabling coordination of rhythms in a timely manner, adaption to environmental changes and more efficient organization of the cellular processes responsible for survival of both the individual and the species. Many components of energy homeostasis exhibit circadian rhythms, which are regulated by central (suprachiasmatic nucleus) and peripheral (located in other tissues) circadian clocks. Adipocyte plays an important role in the regulation of energy homeostasis, the signaling of satiety and cellular differentiation and proliferation. Also, the adipocyte circadian clock is probably involved in the control of many of these functions. Thus, circadian clocks are implicated in the control of energy balance, feeding behavior and consequently in the regulation of body weight. In this regard, alterations in clock genes and rhythms can interfere with the complex mechanism of metabolic and hormonal anticipation, contributing to multifactorial diseases such as obesity and diabetes. The aim of this review was to define circadian clocks by describing their functioning and role in the whole body and in adipocyte metabolism, as well as their influence on body weight control and the development of obesity. PMID:20712885

  6. Coexisting chaotic and periodic dynamics in clock escapements.

    PubMed

    Moon, Francis C; Stiefel, Preston D

    2006-09-15

    This paper addresses the nature of noise in machines. As a concrete example, we examine the dynamics of clock escapements from experimental, historical and analytical points of view. Experiments on two escapement mechanisms from the Reuleaux kinematic collection at Cornell University are used to illustrate chaotic-like noise in clocks. These vibrations coexist with the periodic dynamics of the balance wheel or pendulum. A mathematical model is presented that shows how self-generated chaos in clocks can break the dry friction in the gear train. This model is shown to exhibit a strange attractor in the structural vibration of the clock. The internal feedback between the oscillator and the escapement structure is similar to anti-control of chaos models. PMID:16893802

  7. Daily Rhythmicity of Clock Gene Transcripts in Atlantic Cod Fast Skeletal Muscle

    PubMed Central

    Lazado, Carlo C.; Kumaratunga, Hiruni P. S.; Nagasawa, Kazue; Babiak, Igor; Giannetto, Alessia; Fernandes, Jorge M. O.

    2014-01-01

    The classical notion of a centralized clock that governs circadian rhythmicity has been challenged with the discovery of peripheral oscillators that enable organisms to cope with daily changes in their environment. The present study aimed to identify the molecular clock components in Atlantic cod (Gadus morhua) and to investigate their daily gene expression in fast skeletal muscle. Atlantic cod clock genes were closely related to their orthologs in teleosts and tetrapods. Synteny was conserved to varying degrees in the majority of the 18 clock genes examined. In particular, aryl hydrocarbon receptor nuclear translocator-like 2 (arntl2), RAR-related orphan receptor A (rora) and timeless (tim) displayed high degrees of conservation. Expression profiling during the early ontogenesis revealed that some transcripts were maternally transferred, namely arntl2, cryptochrome 1b and 2 (cry1b and cry2), and period 2a and 2b (per2a and per2b). Most clock genes were ubiquitously expressed in various tissues, suggesting the possible existence of multiple peripheral clock systems in Atlantic cod. In particular, they were all detected in fast skeletal muscle, with the exception of neuronal PAS (Per-Arnt-Single-minded) domain-containing protein (npas1) and rora. Rhythmicity analysis revealed 8 clock genes with daily rhythmic expression, namely arntl2, circadian locomotor output cycles kaput (clock), npas2, cry2, cry3 per2a, nuclear receptor subfamily 1, group D, member 1 (nr1d1), and nr1d2a. Transcript levels of the myogenic genes myogenic factor 5 (myf5) and muscleblind-like 1 (mbnl1) strongly correlated with clock gene expression. This is the first study to unravel the molecular components of peripheral clocks in Atlantic cod. Taken together, our data suggest that the putative clock system in fast skeletal muscle of Atlantic cod has regulatory implications on muscle physiology, particularly in the expression of genes related to myogenesis. PMID:24921252

  8. The Tibetan medicine Zuotai influences clock gene expression in the liver of mice

    PubMed Central

    Li, Huan; Li, Wen-Kai; Lu, Yuan-Fu; Wei, Li-Xin

    2016-01-01

    Background. The circadian clock is involved in drug metabolism, efficacy and toxicity. Drugs could in turn affect the biological clock as a mechanism of their actions. Zuotai is an essential component of many popular Tibetan medicines for sedation, tranquil and “detoxification,” and is mainly composed of metacinnabar (β-HgS). The pharmacological and/or toxicological basis of its action is unknown. This study aimed to examine the effect of Zuotai on biological clock gene expression in the liver of mice. Materials and methods. Mice were orally given Zuotai (10 mg/kg, 1.5-fold of clinical dose) daily for 7 days, and livers were collected every 4 h during the 24 h period. Total RNA was extracted and subjected to real-time RT-PCR analysis of circadian clock gene expression. Results. Zuotai decreased the oscillation amplitude of the clock core gene Clock, neuronal PAS domain protein 2 (Npas2), Brain and muscle Arnt-like protein-1 (Bmal1) at 10:00. For the clock feedback negative control genes, Zuotai had no effect on the oscillation of the clock gene Cryptochrome (Cry1) and Period genes (Per1–3). For the clock-driven target genes, Zuotai increased the oscillation amplitude of the PAR-bZip family member D-box-binding protein (Dbp), decreased nuclear factor interleukin 3 (Nfil3) at 10:00, but had no effect on thyrotroph embryonic factor (Tef); Zuotai increased the expression of nuclear receptor Rev-Erbα (Nr1d1) at 18:00, but had little influence on the nuclear receptor Rev-Erbβ (Nr1d2) and RORα. Conclusion. The Tibetan medicine Zuotai could influence the expression of clock genes, which could contribute to pharmacological and/or toxicological effects of Zuotai. PMID:26855871

  9. A meeting of two chronobiological systems: circadian proteins Period1 and BMAL1 modulate the human hair cycle clock.

    PubMed

    Al-Nuaimi, Yusur; Hardman, Jonathan A; Bíró, Tamás; Haslam, Iain S; Philpott, Michael P; Tóth, Balázs I; Farjo, Nilofer; Farjo, Bessam; Baier, Gerold; Watson, Rachel E B; Grimaldi, Benedetto; Kloepper, Jennifer E; Paus, Ralf

    2014-03-01

    The hair follicle (HF) is a continuously remodeled mini organ that cycles between growth (anagen), regression (catagen), and relative quiescence (telogen). As the anagen-to-catagen transformation of microdissected human scalp HFs can be observed in organ culture, it permits the study of the unknown controls of autonomous, rhythmic tissue remodeling of the HF, which intersects developmental, chronobiological, and growth-regulatory mechanisms. The hypothesis that the peripheral clock system is involved in hair cycle control, i.e., the anagen-to-catagen transformation, was tested. Here we show that in the absence of central clock influences, isolated, organ-cultured human HFs show circadian changes in the gene and protein expression of core clock genes (CLOCK, BMAL1, and Period1) and clock-controlled genes (c-Myc, NR1D1, and CDKN1A), with Period1 expression being hair cycle dependent. Knockdown of either BMAL1 or Period1 in human anagen HFs significantly prolonged anagen. This provides evidence that peripheral core clock genes modulate human HF cycling and are an integral component of the human hair cycle clock. Specifically, our study identifies BMAL1 and Period1 as potential therapeutic targets for modulating human hair growth. PMID:24005054

  10. Dopamine receptor-mediated regulation of neuronal "clock" gene expression.

    PubMed

    Imbesi, M; Yildiz, S; Dirim Arslan, A; Sharma, R; Manev, H; Uz, T

    2009-01-23

    Using a transgenic mice model (i.e. "clock" knockouts), clock transcription factors have been suggested as critical regulators of dopaminergic behaviors induced by drugs of abuse. Moreover, it has been shown that systemic administration of psychostimulants, such as cocaine and methamphetamine regulates the striatal expression of clock genes. However, it is not known whether dopamine receptors mediate these regulatory effects of psychostimulants at the cellular level. Primary striatal neurons in culture express dopamine receptors as well as clock genes and have been successfully used in studying dopamine receptor functioning. Therefore, we investigated the role of dopamine receptors on neuronal clock gene expression in this model using specific receptor agonists. We found an inhibitory effect on the expression of mClock and mPer1 genes with the D2-class (i.e. D2/D3) receptor agonist quinpirole. We also found a generalized stimulatory effect on the expression of clock genes mPer1, mClock, mNPAS2 (neuronal PAS domain protein 2), and mBmal1 with the D1-class (i.e. D1) receptor agonist SKF38393. Further, we tested whether systemic administration of dopamine receptor agonists causes similar changes in striatal clock gene expression in vivo. We found quinpirole-induced alterations in mPER1 protein levels in the mouse striatum (i.e. rhythm shift). Collectively, our results indicate that the dopamine receptor system may mediate psychostimulant-induced changes in clock gene expression. Using striatal neurons in culture as a model, further research is needed to better understand how dopamine signaling modulates the expression dynamics of clock genes (i.e. intracellular signaling pathways) and thereby influences neuronal gene expression, neuronal transmission, and brain functioning. PMID:19017537

  11. The Physiological Period Length of the Human Circadian Clock In Vivo Is Directly Proportional to Period in Human Fibroblasts

    PubMed Central

    Moriggi, Ermanno; Revell, Victoria L.; Hack, Lisa M.; Lockley, Steven W.; Arendt, Josephine; Skene, Debra J.; Meier, Fides; Izakovic, Jan; Wirz-Justice, Anna; Cajochen, Christian; Sergeeva, Oksana J.; Cheresiz, Sergei V.; Danilenko, Konstantin V.; Eckert, Anne; Brown, Steven A.

    2010-01-01

    Background Diurnal behavior in humans is governed by the period length of a circadian clock in the suprachiasmatic nuclei of the brain hypothalamus. Nevertheless, the cell-intrinsic mechanism of this clock is present in most cells of the body. We have shown previously that for individuals of extreme chronotype (“larks” and “owls”), clock properties measured in human fibroblasts correlated with extreme diurnal behavior. Methodology/Principal Findings In this study, we have measured circadian period in human primary fibroblasts taken from normal individuals and, for the first time, compared it directly with physiological period measured in vivo in the same subjects. Human physiological period length was estimated via the secretion pattern of the hormone melatonin in two different groups of sighted subjects and one group of totally blind subjects, each using different methods. Fibroblast period length was measured via cyclical expression of a lentivirally delivered circadian reporter. Within each group, a positive linear correlation was observed between circadian period length in physiology and in fibroblast gene expression. Interestingly, although blind individuals showed on average the same fibroblast clock properties as sighted ones, their physiological periods were significantly longer. Conclusions/Significance We conclude that the period of human circadian behaviour is mostly driven by cellular clock properties in normal individuals and can be approximated by measurement in peripheral cells such as fibroblasts. Based upon differences among sighted and blind subjects, we also speculate that period can be modified by prolonged unusual conditions such as the total light deprivation of blindness. PMID:21042402

  12. Visualizing and Quantifying Intracellular Behavior and Abundance of the Core Circadian Clock Protein PERIOD2.

    PubMed

    Smyllie, Nicola J; Pilorz, Violetta; Boyd, James; Meng, Qing-Jun; Saer, Ben; Chesham, Johanna E; Maywood, Elizabeth S; Krogager, Toke P; Spiller, David G; Boot-Handford, Raymond; White, Michael R H; Hastings, Michael H; Loudon, Andrew S I

    2016-07-25

    Transcriptional-translational feedback loops (TTFLs) are a conserved molecular motif of circadian clocks. The principal clock in mammals is the suprachiasmatic nucleus (SCN) of the hypothalamus. In SCN neurons, auto-regulatory feedback on core clock genes Period (Per) and Cryptochrome (Cry) following nuclear entry of their protein products is the basis of circadian oscillation [1, 2]. In Drosophila clock neurons, the movement of dPer into the nucleus is subject to a circadian gate that generates a delay in the TTFL, and this delay is thought to be critical for oscillation [3, 4]. Analysis of the Drosophila clock has strongly influenced models of the mammalian clock, and such models typically infer complex spatiotemporal, intracellular behaviors of mammalian clock proteins. There are, however, no direct measures of the intracellular behavior of endogenous circadian proteins to support this: dynamic analyses have been limited and often have no circadian dimension [5-7]. We therefore generated a knockin mouse expressing a fluorescent fusion of native PER2 protein (PER2::VENUS) for live imaging. PER2::VENUS recapitulates the circadian functions of wild-type PER2 and, importantly, the behavior of PER2::VENUS runs counter to the Drosophila model: it does not exhibit circadian gating of nuclear entry. Using fluorescent imaging of PER2::VENUS, we acquired the first measures of mobility, molecular concentration, and localization of an endogenous circadian protein in individual mammalian cells, and we showed how the mobility and nuclear translocation of PER2 are regulated by casein kinase. These results provide new qualitative and quantitative insights into the cellular mechanism of the mammalian circadian clock. PMID:27374340

  13. The Circadian Clock in Murine Chondrocytes Regulates Genes Controlling Key Aspects of Cartilage Homeostasis

    PubMed Central

    Gossan, Nicole; Zeef, Leo; Hensman, James; Hughes, Alun; Bateman, John F; Rowley, Lynn; Little, Christopher B; Piggins, Hugh D; Rattray, Magnus; Boot-Handford, Raymond P; Meng, Qing-Jun

    2013-01-01

    ObjectiveTo characterize the circadian clock in murine cartilage tissue and identify tissue-specific clock target genes, and to investigate whether the circadian clock changes during aging or during cartilage degeneration using an experimental mouse model of osteoarthritis (OA). MethodsCartilage explants were obtained from aged and young adult mice after transduction with the circadian clock fusion protein reporter PER2::luc, and real-time bioluminescence recordings were used to characterize the properties of the clock. Time-series microarrays were performed on mouse cartilage tissue to identify genes expressed in a circadian manner. Rhythmic genes were confirmed by quantitative reverse transcription–polymerase chain reaction using mouse tissue, primary chondrocytes, and a human chondrocyte cell line. Experimental OA was induced in mice by destabilization of the medial meniscus (DMM), and articular cartilage samples were microdissected and subjected to microarray analysis. ResultsMouse cartilage tissue and a human chondrocyte cell line were found to contain intrinsic molecular circadian clocks. The cartilage clock could be reset by temperature signals, while the circadian period was temperature compensated. PER2::luc bioluminescence demonstrated that circadian oscillations were significantly lower in amplitude in cartilage from aged mice. Time-series microarray analyses of the mouse tissue identified the first circadian transcriptome in cartilage, revealing that 615 genes (∼3.9% of the expressed genes) displayed a circadian pattern of expression. This included genes involved in cartilage homeostasis and survival, as well as genes with potential importance in the pathogenesis of OA. Several clock genes were disrupted in the early stages of cartilage degeneration in the DMM mouse model of OA. ConclusionThese results reveal an autonomous circadian clock in chondrocytes that can be implicated in key aspects of cartilage biology and pathology. Consequently

  14. Altered Clock Gene Expression in Obese Visceral Adipose Tissue Is Associated with Metabolic Syndrome

    PubMed Central

    C. Figueroa, Ana Lucia; Aranda, Gloria; Momblan, Dulce; Carmona, Francesc; Gomis, Ramon

    2014-01-01

    Clock gene expression was associated with different components of metabolic syndrome (MS) in human adipose tissue. However, no study has been done to compare the expression of clock genes in visceral adipose tissue (VAT) from lean and obese subjects and its clinical implications. Therefore, we studied in lean and obese women the endogenous 24 h expression of clock genes in isolated adipocytes and its association with MS components. VAT was obtained from lean (BMI 21–25 kg/m2; n = 21) and morbidly obese women (BMI >40 kg/m2; n = 28). The 24 h pattern of clock genes was analyzed every 6 hours using RT-PCR. Correlation of clinical data was studied by Spearman analysis. The 24 h pattern of clock genes showed that obesity alters the expression of CLOCK, BMAL1, PER1, CRY2 and REV-ERB ALPHA in adipocytes with changes found in CRY2 and REV-ERB ALPHA throughout the 24 h period. The same results were confirmed in VAT and stromal cells (SC) showing an upregulation of CRY2 and REV-ERB ALPHA from obese women. A positive correlation was observed for REV-ERB ALPHA gene expression with BMI and waist circumference in the obese population. Expression of ROR ALPHA was correlated with HDL levels and CLOCK with LDL. Obese subjects with MS exhibited positive correlation in the PER2 gene with LDL cholesterol, whereas REV-ERB ALPHA was correlated with waist circumference. We identified CRY2 and REV-ERB ALPHA as the clock genes upregulated in obesity during the 24 h period and that REV-ERB ALPHA is an important gene associated with MS. PMID:25365257

  15. The Clock gene clone and its circadian rhythms in Pelteobagrus vachelli

    NASA Astrophysics Data System (ADS)

    Qin, Chuanjie; Shao, Ting

    2015-05-01

    The Clock gene, a key molecule in circadian systems, is widely distributed in the animal kingdom. We isolated a 936-bp partial cDNA sequence of the Clock gene ( Pva-clock) from the darkbarbel catfish Pelteobagrus vachelli that exhibited high identity with Clock genes of other species of fish and animals (65%-88%). The putative domains included a basic helix-loop-helix (bHLH) domain and two period-ARNT-single-minded (PAS) domains, which were also similar to those in other species of fish and animals. Pva-Clock was primarily expressed in the brain, and was detected in all of the peripheral tissues sampled. Additionally, the pattern of Pva-Clock expression over a 24-h period exhibited a circadian rhythm in the brain, liver and intestine, with the acrophase at zeitgeber time 21:35, 23:00, and 23:23, respectively. Our results provide insight into the function of the molecular Clock of P. vachelli.

  16. Expression of clock genes in human subcutaneous and visceral adipose tissues.

    PubMed

    Zanquetta, Melissa Moreira; Correa-Giannella, Maria Lúcia; Giannella-Neto, Daniel; Alonso, Paulino Alberto; Guimarães, Ligia Maria Martins Vaz; Meyer, Alberto; Villares, Sandra Mara Ferreira

    2012-04-01

    Disrupted circadian rhythms are associated with obesity and metabolic alterations, but little is known about the participation of peripheral circadian clock machinery in these processes. The aim of the present study was to analyze RNA expression of clock genes in subcutaneous (SAT) and visceral (VAT) adipose tissues of male and female subjects in AM (morning) and PM (afternoon) periods, and its interactions with body mass index (BMI). Ninety-one subjects (41 ± 11 yrs of age) presenting a wide range of BMI (21.4 to 48.6 kg/m(2)) were included. SAT and VAT biopsies were obtained from patients undergoing abdominal surgeries. Clock genes expressions were evaluated by qRT-PCR. The only clock gene that showed higher expression (p < .0001) in SAT in comparison to VAT was PER1 of female (372%) and male (326%) subjects. Different patterns of expression between the AM and PM periods were observed, in particular REV-ERBα, which was reduced (p < .05) at the PM period in SAT and VAT of both women and men (women: ∼53% lower; men: ∼78% lower), whereas CLOCK expression was not altered. Relationships between clock genes were different in SAT vs. VAT. BMI was negatively correlated with SATPER1 (r = -.549; p = .001) and SATPER2 (r = -.613; p = .0001) and positively with VATCLOCK (r = .541; p = .001) and VATBMAL1 (r = .468; p = .007) only in women. These data suggest that the circadian clock machinery of adipose tissue depots differs between female and male subjects, with a sex-specific effect observed for some genes. BMI correlated with clock genes, but at this moment it is not possible to establish the cause-effect relationship. PMID:22390238

  17. Circadian Gene Clock Regulates Psoriasis-Like Skin Inflammation in Mice

    PubMed Central

    Ando, Noriko; Nakamura, Yuki; Aoki, Rui; Ishimaru, Kayoko; Ogawa, Hideoki; Okumura, Ko; Shibata, Shigenobu; Shimada, Shinji; Nakao, Atsuhito

    2015-01-01

    There are several reports suggesting that the pathophysiology of psoriasis may be associated with aberrant circadian rhythms. However, the mechanistic link between psoriasis and the circadian time-keeping system, “the circadian clock,” remains unclear. This study determined whether the core circadian gene, Clock, had a regulatory role in the development of psoriasis. For this purpose, we compared the development of psoriasis-like skin inflammation induced by the Toll-like receptor 7 ligand imiquimod (IMQ) between wild-type mice and mice with a loss-of-function mutation of Clock. We also compared the development of IMQ-induced dermatitis between wild-type mice and mice with a loss-of-function mutation of Period2 (Per2), another key circadian gene that inhibits CLOCK activity. We found that Clock mutation ameliorated IMQ-induced dermatitis, whereas the Per2 mutation exaggerated IMQ-induced dermatitis, when compared with wild-type mice associated with decreased or increased IL-23 receptor (IL-23R) expression in γ/δ+ T cells, respectively. In addition, CLOCK directly bound to the promoter of IL-23R in γ/δ+ T cells, and IL-23R expression in the mouse skin was under circadian control. These findings suggest that Clock is a novel regulator of psoriasis-like skin inflammation in mice via direct modulation of IL-23R expression in γ/δ+ T cells, establishing a mechanistic link between psoriasis and the circadian clock. PMID:26291684

  18. Clock gene expression in the liver of streptozotocin-induced and spontaneous type 1 diabetic rats.

    PubMed

    Hofmann, K; Schönerstedt, U; Mühlbauer, E; Wedekind, D; Peschke, E

    2013-09-01

    Several investigations have shown a relation between diabetes and alterations of the liver circadian clock. We investigated the diurnal expression of clock genes and clock-controlled genes (CCGs) in 3-hour intervals for a 24-h period in the livers of male streptozotocin (STZ)-treated rats, male spontaneous type 1 diabetic LEW.1AR1-iddm (Iddm) rats, and Iddm rats treated for 10 days with insulin. Hepatic mRNA was extracted, and the relative expression of clock genes (Per1, Per2, Bmal1, Clock, Cry1), as well as CCGs (Dbp, E4bp4, RevErbα, Rorα, Pparγ), was analyzed by reverse transcription followed by real-time polymerase chain reaction. Diabetic STZ and Iddm rats, as well as insulin-substituted Iddm rats, exhibited a significant diurnal expression pattern of clock genes as determined by Cosinor analysis; however, the MESOR (midline estimating statistic of rhythm) of Bmal1, Per2, and Clock transcript expression was altered in Iddm and insulin-substituted Iddm rats. The hepatic expression of the CCGs Dbp and RevErbα revealed a diurnal rhythm in all investigated groups. Insulin administration to Iddm rats normalized the enhanced MESOR in the expression of Dbp, RevErbα, and E4bp4 to the levels of normoglycemic controls. Cosinor analysis indicated no diurnal rhythm of Pparγ expression in the livers of diabetic STZ or Iddm rats or in those of insulin-substituted Iddm rats. Also, insulin substitution could not reverse the decreased MESOR of Pparγ expression in Iddm rats. In consequence of the diabetic disease, changes in the expression of clock genes and CCGs suggest alterations in the hepatic peripheral clock mechanism. PMID:23632905

  19. Discrete gene replication events drive coupling between the cell cycle and circadian clocks

    PubMed Central

    Paijmans, Joris; Bosman, Mark; ten Wolde, Pieter Rein; Lubensky, David K.

    2016-01-01

    Many organisms possess both a cell cycle to control DNA replication and a circadian clock to anticipate changes between day and night. In some cases, these two rhythmic systems are known to be coupled by specific, cross-regulatory interactions. Here, we use mathematical modeling to show that, additionally, the cell cycle generically influences circadian clocks in a nonspecific fashion: The regular, discrete jumps in gene-copy number arising from DNA replication during the cell cycle cause a periodic driving of the circadian clock, which can dramatically alter its behavior and impair its function. A clock built on negative transcriptional feedback either phase-locks to the cell cycle, so that the clock period tracks the cell division time, or exhibits erratic behavior. We argue that the cyanobacterium Synechococcus elongatus has evolved two features that protect its clock from such disturbances, both of which are needed to fully insulate it from the cell cycle and give it its observed robustness: a phosphorylation-based protein modification oscillator, together with its accompanying push–pull read-out circuit that responds primarily to the ratios of different phosphoform concentrations, makes the clock less susceptible to perturbations in protein synthesis; the presence of multiple, asynchronously replicating copies of the same chromosome diminishes the effect of replicating any single copy of a gene. PMID:27035936

  20. Association between Circadian Clock Genes and Diapause Incidence in Drosophila triauraria

    PubMed Central

    Yamada, Hirokazu; Yamamoto, Masa-Toshi

    2011-01-01

    Diapause is an adaptive response triggered by seasonal photoperiodicity to overcome unfavorable seasons. The photoperiodic clock is a system that controls seasonal physiological processes, but our knowledge about its physiological mechanisms and genetic architecture remains incomplete. The circadian clock is another system that controls daily rhythmic physiological phenomena. It has been argued that there is a connection between the two clocks. To examine the genetic connection between them, we analyzed the associations of five circadian clock genes (period, timeless, Clock, cycle and cryptochrome) with the occurrence of diapause in Drosophila triauraria, which shows a robust reproductive diapause with clear photoperiodicity. Non-diapause strains found in low latitudes were compared in genetic crosses with the diapause strain, in which the diapause trait is clearly dominant. Single nucleotide polymorphism and deletion analyses of the five circadian clock genes in backcross progeny revealed that allelic differences in timeless and cryptochrome between the strains were additively associated with the differences in the incidence of diapause. This suggests that there is a molecular link between certain circadian clock genes and the occurrence of diapause. PMID:22164210

  1. The clock protein period 2 synchronizes mitotic expansion and decidual transformation of human endometrial stromal cells.

    PubMed

    Muter, Joanne; Lucas, Emma S; Chan, Yi-Wah; Brighton, Paul J; Moore, Jonathan D; Lacey, Lauren; Quenby, Siobhan; Lam, Eric W-F; Brosens, Jan J

    2015-04-01

    Implantation requires coordinated interactions between the conceptus and surrounding decidual cells, but the involvement of clock genes in this process is incompletely understood. Circadian oscillations are predicated on transcriptional-translational feedback loops, which balance the activities of the transcriptional activators CLOCK (circadian locomotor output cycles kaput) and brain muscle arnt-like 1 and repressors encoded by PER (Period) and Cryptochrome genes. We show that loss of PER2 expression silences circadian oscillations in decidualizing human endometrial stromal cells (HESCs). Down-regulation occurred between 12 and 24 hours following differentiation and coincided with reduced CLOCK binding to a noncanonical E-box enhancer in the PER2 promoter. RNA sequencing revealed that premature inhibition of PER2 by small interfering RNA knockdown leads to a grossly disorganized decidual response. Gene ontology analysis highlighted a preponderance of cell cycle regulators among the 1121 genes perturbed upon PER2 knockdown. Congruently, PER2 inhibition abrogated mitotic expansion of differentiating HESCs by inducing cell cycle block at G2/M. Analysis of 70 midluteal endometrial biopsies revealed an inverse correlation between PER2 transcript levels and the number of miscarriages in women suffering reproductive failure (Spearman rank test, ρ = -0.3260; P = 0.0046). Thus, PER2 synchronizes endometrial proliferation with initiation of aperiodic decidual gene expression; uncoupling of these events may cause recurrent pregnancy loss. PMID:25573754

  2. Temporal Expression of the Clock Genes in the Water Flea Daphnia pulex (Crustacea: Cladocera).

    PubMed

    Bernatowicz, Piotr P; Kotwica-Rolinska, Joanna; Joachimiak, Ewa; Sikora, Anna; Polanska, Marta A; Pijanowska, Joanna; Bębas, Piotr

    2016-04-01

    The timekeeping mechanisms that operate at the core of circadian clocks (oscillators) are based on interacting molecular feedback loops consisting of clock and clock-associated genes. However, there is a lack of comprehensive studies on the expression of clock genes (particularly those forming its core) in single crustacean species at the mRNA and protein levels, and these studies could serve as a basis for constructing a model of the crustacean molecular oscillator. Studies on Daphnia pulex are well suited to fill this gap because this species is the only representative crustacean whose genome has been sequenced. We analyzed the abundance of 20 gene transcripts throughout the day in the whole bodies of D. pulex (single clone); we found that 15 of these genes were transcriptionally active, and most had daily expression level changes. According to the functional classification of their homologues in insects, these genes may represent elements of the Daphnia molecular oscillator core and its input and output pathways. Studies of PERIOD (PER) protein, one of the main clock components, revealed its rhythmic expression pattern in the epidermis, gut, and ovaries. Finally, the cycling levels of many of these clock components observed in animals reared in continuous light led to the conclusion that the Daphnia oscillator, even if it is structurally similar to the oscillators of other arthropods, can be considered a particularly important adaptive mechanism for living in environments with extreme photoperiods. PMID:27170555

  3. The clock protein period 2 synchronizes mitotic expansion and decidual transformation of human endometrial stromal cells

    PubMed Central

    Muter, Joanne; Lucas, Emma S.; Chan, Yi-Wah; Brighton, Paul J.; Moore, Jonathan D.; Lacey, Lauren; Quenby, Siobhan; Lam, Eric W.-F.; Brosens, Jan J.

    2015-01-01

    Implantation requires coordinated interactions between the conceptus and surrounding decidual cells, but the involvement of clock genes in this process is incompletely understood. Circadian oscillations are predicated on transcriptional-translational feedback loops, which balance the activities of the transcriptional activators CLOCK (circadian locomotor output cycles kaput) and brain muscle arnt-like 1 and repressors encoded by PER (Period) and Cryptochrome genes. We show that loss of PER2 expression silences circadian oscillations in decidualizing human endometrial stromal cells (HESCs). Down-regulation occurred between 12 and 24 hours following differentiation and coincided with reduced CLOCK binding to a noncanonical E-box enhancer in the PER2 promoter. RNA sequencing revealed that premature inhibition of PER2 by small interfering RNA knockdown leads to a grossly disorganized decidual response. Gene ontology analysis highlighted a preponderance of cell cycle regulators among the 1121 genes perturbed upon PER2 knockdown. Congruently, PER2 inhibition abrogated mitotic expansion of differentiating HESCs by inducing cell cycle block at G2/M. Analysis of 70 midluteal endometrial biopsies revealed an inverse correlation between PER2 transcript levels and the number of miscarriages in women suffering reproductive failure (Spearman rank test, ρ = −0.3260; P = 0.0046). Thus, PER2 synchronizes endometrial proliferation with initiation of aperiodic decidual gene expression; uncoupling of these events may cause recurrent pregnancy loss.—Muter, J., Lucas, E. S., Chan, Y.-W., Brighton, P. J., Moore, J. D., Lacey, L., Quenby, S., Lam, E. W.-F., Brosens, J. J. The clock protein period 2 synchronizes mitotic expansion and decidual transformation of human endometrial stromal cells. PMID:25573754

  4. Clock genes × stress × reward interactions in alcohol and substance use disorders.

    PubMed

    Perreau-Lenz, Stéphanie; Spanagel, Rainer

    2015-06-01

    Adverse life events and highly stressful environments have deleterious consequences for mental health. Those environmental factors can potentiate alcohol and drug abuse in vulnerable individuals carrying specific genetic risk factors, hence producing the final risk for alcohol- and substance-use disorders development. The nature of these genes remains to be fully determined, but studies indicate their direct or indirect relation to the stress hypothalamo-pituitary-adrenal (HPA) axis and/or reward systems. Over the past decade, clock genes have been revealed to be key-players in influencing acute and chronic alcohol/drug effects. In parallel, the influence of chronic stress and stressful life events in promoting alcohol and substance use and abuse has been demonstrated. Furthermore, the reciprocal interaction of clock genes with various HPA-axis components, as well as the evidence for an implication of clock genes in stress-induced alcohol abuse, have led to the idea that clock genes, and Period genes in particular, may represent key genetic factors to consider when examining gene × environment interaction in the etiology of addiction. The aim of the present review is to summarize findings linking clock genes, stress, and alcohol and substance abuse, and to propose potential underlying neurobiological mechanisms. PMID:25943583

  5. p53 Regulates Period2 Expression and the Circadian Clock

    PubMed Central

    Miki, Takao; Matsumoto, Tomoko; Zhao, Zhaoyang; Lee, Cheng Chi

    2013-01-01

    The mechanistic interconnectivity between circadian regulation and the genotoxic stress response remains poorly understood. Here we show that the expression of Period 2 (Per2), a circadian regulator, is directly regulated by p53 binding to a response element in the Per2 promoter. This p53 response element is evolutionarily conserved and overlaps with the E-Box element critical for BMAL1/CLOCK binding and its transcriptional activation of Per2 expression. Our studies reveal that p53 blocks BMAL1/CLOCK binding to the Per2 promoter leading to repression of Per2 expression. In the suprachiasmatic nucleus (SCN), p53 expression and its binding to the Per2 promoter are under circadian control. Per2 expression in the SCN is altered by p53 deficiency or stabilization of p53 by Nutlin-3. Behaviorally, p53−/− mice have a shorter period length that lacks stability and they exhibit impaired photo-entrainment to a light pulse under a free-running state. Our studies demonstrate that p53 modulates mouse circadian behavior. PMID:24051492

  6. Rapid attenuation of circadian clock gene oscillations in the rat heart following ischemia-reperfusion.

    PubMed

    Kung, Theodore A; Egbejimi, Oluwaseun; Cui, Jiajia; Ha, Ngan P; Durgan, David J; Essop, M Faadiel; Bray, Molly S; Shaw, Chad A; Hardin, Paul E; Stanley, William C; Young, Martin E

    2007-12-01

    The intracellular circadian clock consists of a series of transcriptional modulators that together allow the cell to perceive the time of day. Circadian clocks have been identified within various components of the cardiovascular system (e.g. cardiomyocytes, vascular smooth muscle cells) and possess the potential to regulate numerous aspects of cardiovascular physiology and pathophysiology. The present study tested the hypothesis that ischemia/reperfusion (I/R; 30 min occlusion of the rat left main coronary artery in vivo) alters the circadian clock within the ischemic, versus non-ischemic, region of the heart. Left ventricular anterior (ischemic) and posterior (non-ischemic) regions were isolated from I/R, sham-operated, and naïve rats over a 24-h period, after which mRNAs encoding for both circadian clock components and known clock-controlled genes were quantified. Circadian clock gene oscillations (i.e. peak-to-trough fold differences) were rapidly attenuated in the I/R, versus the non-ischemic, region. Consistent with decreased circadian clock output, we observe a rapid induction of E4BP4 in the ischemic region of the heart at both the mRNA and protein levels. In contrast with I/R, chronic (1 week) hypobaric chamber-induced hypoxia did not attenuate oscillations in circadian clock genes in either the left or right ventricle of the rat heart. In conclusion, these data show that in a rodent model of myocardial I/R, circadian clocks within the ischemic region become rapidly impaired, through a mechanism that appears to be independent of hypoxia. PMID:17959196

  7. The clock gene cycle plays an important role in the circadian clock of the cricket Gryllus bimaculatus.

    PubMed

    Uryu, Outa; Karpova, Svetlana G; Tomioka, Kenji

    2013-07-01

    To dissect the molecular oscillatory mechanism of the circadian clock in the cricket Gryllus bimaculatus, we have cloned a cDNA of the clock gene cycle (Gb'cyc) and analyzed its structure and function. Gb'cyc contains four functional domains, i.e. bHLH, PAS-A, PAS-B and BCTR domains, and is expressed rhythmically in light dark cycles, peaking at mid night. The RNA interference (RNAi) of Clock (Gb'Clk) and period (Gb'per) reduced the Gb'cyc mRNA levels and abolished the rhythmic expression, suggesting that the rhythmic expression of Gb'cyc is regulated by a mechanism including Gb'Clk and Gb'per. These features are more similar to those of mammalian orthologue of cyc (Bmal1) than those of Drosophila cyc. A single treatment with double-stranded RNA (dsRNA) of Gb'cyc effectively knocked down the Gb'cyc mRNA level and abolished its rhythmic expression. The cyc RNAi failed to disrupt the locomotor rhythm, but lengthened its free-running period in constant darkness (DD). It is thus likely that Gb'cyc is involved in the circadian clock machinery of the cricket. The cyc RNAi crickets showed a rhythmic expression of Gb'per and timeless (Gb'tim) in the optic lobe in DD, explaining the persistence of the locomotor rhythm. Surprisingly, cyc RNAi revealed a rhythmic expression of Gb'Clk in DD which is otherwise rather constitutively expressed in the optic lobe. These facts suggest that the cricket might have a unique clock oscillatory mechanism in which both Gb'cyc and Gb'Clk are rhythmically controlled and that under abundant expression of Gb'cyc the rhythmic expression of Gb'Clk may be concealed. PMID:23665334

  8. From light to genes: moving the hands of the circadian clock.

    PubMed

    Golombek, Diego A; Ferreyra, Gabriela A; Agostino, Patricia V; Murad, Alejandro D; Rubio, María F; Pizzio, Gastón A; Katz, Marcelo E; Marpegan, Luciano; Bekinschtein, Tristán A

    2003-05-01

    Mammalian circadian rhythms are generated by the hypothalamic suprachiasmatic nuclei and finely tuned to environmental periodicities by neurochemical responses to the light-dark cycle. Light reaches the clock through a direct retinohypothalamic tract, primarily through glutamatergic innervation, and its action is probably regulated by a variety of other neurotransmitters. A key second messenger in circadian photic entrainment is calcium, mobilized through membrane channels or intracellular reservoirs, which triggers the activation of several enzymes, including a calcium/calmodulin-dependent protein kinase and nitric oxide synthase. Other enzymes activated by light are mitogen-activated- and cGMP-dependent protein kinase; all of the above have been reported to be involved in the circadian responses to nocturnal light pulses. These mechanisms lead to expression of specific clock genes which eventually set the phase of the clock and of clock-controlled circadian rhythms. PMID:12700026

  9. Direct Repression of Evening Genes by CIRCADIAN CLOCK-ASSOCIATED1 in the Arabidopsis Circadian Clock.

    PubMed

    Kamioka, Mari; Takao, Saori; Suzuki, Takamasa; Taki, Kyomi; Higashiyama, Tetsuya; Kinoshita, Toshinori; Nakamichi, Norihito

    2016-03-01

    The circadian clock is a biological timekeeping system that provides organisms with the ability to adapt to day-night cycles. Timing of the expression of four members of theArabidopsis thaliana PSEUDO-RESPONSE REGULATOR(PRR) family is crucial for proper clock function, and transcriptional control ofPRRsremains incompletely defined. Here, we demonstrate that direct regulation ofPRR5by CIRCADIAN CLOCK-ASSOCIATED1 (CCA1) determines the repression state ofPRR5in the morning. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) analyses indicated that CCA1 associates with three separate regions upstream ofPRR5 CCA1 and its homolog LATE ELONGATED HYPOCOTYL (LHY) suppressedPRR5promoter activity in a transient assay. The regions bound by CCA1 in thePRR5promoter gave rhythmic patterns with troughs in the morning, when CCA1 and LHY are at high levels. Furthermore,ChIP-seqrevealed that CCA1 associates with at least 449 loci with 863 adjacent genes. Importantly, this gene set contains genes that are repressed but upregulated incca1 lhydouble mutants in the morning. This study shows that direct binding by CCA1 in the morning provides strong repression ofPRR5, and repression by CCA1 also temporally regulates an evening-expressed gene set that includesPRR5. PMID:26941090

  10. Circadian Clock-Regulated Expression of Phytochrome and Cryptochrome Genes in Arabidopsis1

    PubMed Central

    Tóth, Réka; Kevei, Éva; Hall, Anthony; Millar, Andrew J.; Nagy, Ferenc; Kozma-Bognár, László

    2001-01-01

    Many physiological and biochemical processes in plants exhibit endogenous rhythms with a period of about 24 h. Endogenous oscillators called circadian clocks regulate these rhythms. The circadian clocks are synchronized to the periodic environmental changes (e.g. day/night cycles) by specific stimuli; among these, the most important is the light. Photoreceptors, phytochromes, and cryptochromes are involved in setting the clock by transducing the light signal to the central oscillator. In this work, we analyzed the spatial, temporal, and long-term light-regulated expression patterns of the Arabidopsis phytochrome (PHYA to PHYE) and cryptochrome (CRY1 and CRY2) promoters fused to the luciferase (LUC+) reporter gene. The results revealed new details of the tissue-specific expression and light regulation of the PHYC and CRY1 and 2 promoters. More importantly, the data obtained demonstrate that the activities of the promoter::LUC+ constructs, with the exception of PHYC::LUC+, display circadian oscillations under constant conditions. In addition, it is shown by measuring the mRNA abundance of PHY and CRY genes under constant light conditions that the circadian control is also maintained at the level of mRNA accumulation. These observations indicate that the plant circadian clock controls the expression of these photoreceptors, revealing the formation of a new regulatory loop that could modulate gating and resetting of the circadian clock. PMID:11743105

  11. Periodic dip of lipidperoxidation in humans: a redox signal to synchronize peripheral circadian clocks?

    PubMed

    Cardona, F

    2004-01-01

    The output generated by the endogenous circadian clock to control circadian functions and temporal organization in metazoans is unknown. Redox state perturbations generated by reactive oxygen species (ROS) and antioxidants are known to influence the expression of a number of genes and signal transduction pathways. Evidence has been recently provided that the reduced redox cofactors NAD and NADP both regulate clock gene activity in the suprachiasmatic nucleus (SCN) and are induced by it. Significant periodic variations of lipidperoxidation in human blood with a dip at 04.00 h have been previously reported. Such variations could be expected to alter the cellular redox state, thus possibly functioning as periodic redox signals from the master clock. To verify the existence of the mentioned variations the serum levels of malondialdehyde (MDA), a marker of lipidperoxidation, were monitored by High-Performance Liquid Chromatography in 39 healthy subjects at 3-h intervals over a 24-h period. Throughout the test period, only biological noise could be detected in all test persons. However, the normalized MDA levels at 03.00 h were significantly lower (p < 0.05 to < 0.00005) in 38 (97%) of the cases and showed a significantly lower standard deviation (p < 0.004) than at any of the other 3-h intervals, indicating a periodic dip of lipidperoxidation (PDL) in diurnal active subjects. We hypothesize that the PDL, on the basis of its time of appearance, its frequency and its potential influence on cellular redox state, represents a periodic systemic redox output of the SCN, in terms of a relatively short and sudden interruption of the daily oxidative noise. According to recent research, it could be the result of redox alterations induced by the SCN activity and at the same time the pathway by which the master clock resets and synchronizes peripheral oscillators to the light/dark cycle. Additionally, the antioxidative function of the pineal gland activity postulated elsewhere

  12. Sexual dimorphism in clock genes expression in human adipose tissue

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was carried out to investigate whether sex-related differences exist in the adipocyte expression of clock genes from subcutaneous abdominal and visceral fat depots in severely obese patients. METHODS: We investigated 16 morbidly obese patients, eight men and eight women (mean age 45 +/- 2...

  13. Bidirectional CLOCK/BMAL1-dependent circadian gene regulation by retinoic acid in vitro

    SciTech Connect

    Shirai, Hidenori; Oishi, Katsutaka; Ishida, Norio . E-mail: n.ishida@aist.go.jp

    2006-12-15

    A central circadian clock located in the suprachiasmatic nucleus (SCN) of the mammalian hypothalamus entrains peripheral clocks through both neural and humoral factors. Although candidates for entrainment factors have been described, their details remain obscure. Here, we screened ligands for nuclear receptors that affect CLOCK/BMAL1-dependent transactivation of the mouse Period1 (mPer1) gene in NIH3T3 cells. We found that retinoic acids (RAs) significantly up-regulate mPer1 expression in an E-box-dependent manner. We also found that RAs up-regulate the expression of other E-box-dependent circadian genes such as mPer2, arginine vasopressin (mAVP), and peroxisome proliferator-activated receptor {alpha} (mPPAR{alpha}). Surprisingly, the effect of RAs on CLOCK/BMAL1 (E-box)-dependent mRNA expression was bidirectional and depended on the presence of exogenous retinoic acid receptor {alpha} (RAR{alpha}). These results suggest that RAs regulate the CLOCK/BMAL1-dependent transcription of circadian genes in a complex manner.

  14. Identification of putative circadian clock genes in the American horseshoe crab, Limulus polyphemus.

    PubMed

    Chesmore, Kevin N; Watson, Winsor H; Chabot, Christopher C

    2016-09-01

    While the American horseshoe crab, Limulus polyphemus, has robust circadian and circatidal rhythms, virtually nothing is known about the molecular basis of these rhythms in this species or any other chelicerate. In this study, next generation sequencing was used to assemble transcriptomic reads and then putative homologs of known core and accessory circadian genes were identified in these databases. Homologous transcripts were discovered for one circadian clock input gene, five core genes, 22 accessory genes, and two possible output pathways. Alignments and functional domain analyses showed generally high conservation between the putative L. polyphemus clock genes and homologs from Drosophila melanogaster and Daphnia pulex. The presence of both cry1 and cry2 in the L. polyphemus transcriptome would classify its system as an "ancestral", type 2 clock system. In addition, a novel duplication of CYCLE, and a novel triplication of PERIOD were found. Investigations are currently underway to determine if any of these "circadian" genes also participate in the molecular processes that drive the Limulus circatidal clock. PMID:27341138

  15. Circadian transcriptional regulation by the posttranslational oscillator without de novo clock gene expression in Synechococcus

    PubMed Central

    Hosokawa, Norimune; Hatakeyama, Tetsuhiro S.; Kojima, Takashi; Kikuchi, Yoshiyuki; Ito, Hiroshi; Iwasaki, Hideo

    2011-01-01

    Circadian rhythms are a fundamental property of most organisms, from cyanobacteria to humans. In the unicellular obligately photoautotrophic cyanobacterium Synechococcus elongatus PCC 7942, essentially all promoter activities are controlled by the KaiABC-based clock under continuous light conditions. When Synechococcus cells are transferred from the light to continuous dark (DD) conditions, the expression of most genes, including the clock genes kaiA and kaiBC, is rapidly down-regulated, whereas the KaiC phosphorylation cycle persists. Therefore, we speculated that the posttranslational oscillator might not drive the transcriptional circadian output without de novo expression of the kai genes. Here we show that the cyanobacterial clock regulates the transcriptional output even in the dark. The expression of a subset of genes in the genomes of cells grown in the dark was dramatically affected by kaiABC nullification, and the magnitude of dark induction was dependent on the time at which the cells were transferred from the light to the dark. Moreover, under DD conditions, the expression of some dark-induced gene transcripts exhibited temperature-compensated damped oscillations, which were nullified in kaiABC-null strains and were affected by a kaiC period mutation. These results indicate that the Kai protein-based posttranslational oscillator can drive the circadian transcriptional output even without the de novo expression of the clock genes. PMID:21896749

  16. Using Fractional Clock-Period Delays in Telemetry Arraying

    NASA Technical Reports Server (NTRS)

    Fort, David; Rogstad, David; Rogstad, Stephen P.

    2003-01-01

    A set of special digital all-pass finite-impulse- response (FIR) filters produces phase shifts equivalent to delays that equal fractions of the sampling or clock period of a telemetry-data-processing system. These filters have been used to enhance the arraying of telemetry signals that have been received at multiple ground stations from spacecraft (see figure). Somewhat more specifically, these filters have been used to align, in the time domain, the telemetry-data sequences received by the various antennas, in order to maximize the signal-to-noise ratio of the composite telemetric signal obtained by summing the signals received by the antennas. The term arraying in this context denotes a method of enhanced reception of telemetry signals in which several antennas are used to track a single spacecraft. Each antenna receives a signal that comprises a sum of telemetry data plus noise, and these sum data are sent to an arraying combiner for processing. Correlation is the means used to align the set of data from one antenna with that from another antenna. After the data from all the antennas have been aligned in the time domain, they are all added together, sample by sample.

  17. Persistence, period and precision of autonomous cellular oscillators from the zebrafish segmentation clock

    PubMed Central

    Webb, Alexis B; Lengyel, Iván M; Jörg, David J; Valentin, Guillaume; Jülicher, Frank; Morelli, Luis G; Oates, Andrew C

    2016-01-01

    In vertebrate development, the sequential and rhythmic segmentation of the body axis is regulated by a “segmentation clock”. This clock is comprised of a population of coordinated oscillating cells that together produce rhythmic gene expression patterns in the embryo. Whether individual cells autonomously maintain oscillations, or whether oscillations depend on signals from neighboring cells is unknown. Using a transgenic zebrafish reporter line for the cyclic transcription factor Her1, we recorded single tailbud cells in vitro. We demonstrate that individual cells can behave as autonomous cellular oscillators. We described the observed variability in cell behavior using a theory of generic oscillators with correlated noise. Single cells have longer periods and lower precision than the tissue, highlighting the role of collective processes in the segmentation clock. Our work reveals a population of cells from the zebrafish segmentation clock that behave as self-sustained, autonomous oscillators with distinctive noisy dynamics. DOI: http://dx.doi.org/10.7554/eLife.08438.001 PMID:26880542

  18. Circadian Rhythmicity of Active GSK3 Isoforms Modulates Molecular Clock Gene Rhythms in the Suprachiasmatic Nucleus

    PubMed Central

    Besing, R.C.; Paul, J.R.; Hablitz, L.M.; Rogers, C.O.; Johnson, R.L.; Young, M.E.; Gamble, K.L.

    2015-01-01

    The suprachiasmatic nucleus (SCN) drives and synchronizes daily rhythms at the cellular level via transcriptional-translational feedback loops comprised of clock genes such as Bmal1 and Period (Per). Glycogen synthase kinase 3 (GSK3), a serine/threonine kinase, phosphorylates at least five core clock proteins and shows diurnal variation in phosphorylation state (inactivation) of the GSK3β isoform. Whether phosphorylation of the other primary isoform (GSK3α) varies across the subjective day-night cycle is unknown. The purpose of this study was to determine if the endogenous rhythm of GSK3 (α and β) phosphorylation is critical for rhythmic BMAL1 expression and normal amplitude and periodicity of the molecular clock in the SCN. Significant circadian rhythmicity of phosphorylated GSK3 (α and β) was observed in the SCN from wild-type mice housed in constant darkness for two weeks. Importantly, chronic activation of both GSK3 isoforms impaired rhythmicity of the GSK3 target BMAL1. Furthermore, chronic pharmacological inhibition of GSK3 with 20 μM CHIR-99021 enhanced the amplitude and shortened the period of PER2::luciferase rhythms in organotypic SCN slice cultures. These results support the model that GSK3 activity status is regulated by the circadian clock and that GSK3 feeds back to regulate the molecular clock amplitude in the SCN. PMID:25724980

  19. Butyrate Infusions in the Ovine Fetus Delay the Biologic Clock for Globin Gene Switching

    NASA Astrophysics Data System (ADS)

    Perrine, Susan P.; Rudolph, Abraham; Faller, Douglas V.; Roman, Christine; Cohen, Ruth A.; Chen, Shao-Jing; Kan, Yuet Wai

    1988-11-01

    The switch from fetal to adult hemoglobin expression is regulated in many mammalian species by a developmental clock-like mechanism and determined by the gestational age of the fetus. Prolonging fetal globin gene expression is of considerable interest for therapeutic potential in diseases caused by abnormal β -globin genes. Butyric acid, which is found in increased plasma concentrations in infants of diabetic mothers who have delayed globin gene switching, was infused into catheterized fetal lambs in utero during the time of the normal globin gene switch period. The globin gene switch was significantly delayed in three of four butyrate-treated fetuses compared with controls and was entirely prevented in one fetus in whom the infusion was begun before the globin switch was under way. These data provide a model for investigating and arresting the biologic clock of hemoglobin switching.

  20. Variations in Phase and Amplitude of Rhythmic Clock Gene Expression across Prefrontal Cortex, Hippocampus, Amygdala, and Hypothalamic Paraventricular and Suprachiasmatic Nuclei of Male and Female Rats.

    PubMed

    Chun, Lauren E; Woodruff, Elizabeth R; Morton, Sarah; Hinds, Laura R; Spencer, Robert L

    2015-10-01

    The molecular circadian clock is a self-regulating transcription/translation cycle of positive (Bmal1, Clock/Npas2) and negative (Per1,2,3, Cry1,2) regulatory components. While the molecular clock has been well characterized in the body's master circadian pacemaker, the hypothalamic suprachiasmatic nucleus (SCN), only a few studies have examined both the positive and negative clock components in extra-SCN brain tissue. Furthermore, there has yet to be a direct comparison of male and female clock gene expression in the brain. This comparison is warranted, as there are sex differences in circadian functioning and disorders associated with disrupted clock gene expression. This study examined basal clock gene expression (Per1, Per2, Bmal1 mRNA) in the SCN, prefrontal cortex (PFC), rostral agranular insula, hypothalamic paraventricular nucleus (PVN), amygdala, and hippocampus of male and female rats at 4-h intervals throughout a 12:12 h light:dark cycle. There was a significant rhythm of Per1, Per2, and Bmal1 in the SCN, PFC, insula, PVN, subregions of the hippocampus, and amygdala with a 24-h period, suggesting the importance of an oscillating molecular clock in extra-SCN brain regions. There were 3 distinct clock gene expression profiles across the brain regions, indicative of diversity among brain clocks. Although, generally, the clock gene expression profiles were similar between male and female rats, there were some sex differences in the robustness of clock gene expression (e.g., females had fewer robust rhythms in the medial PFC, more robust rhythms in the hippocampus, and a greater mesor in the medial amygdala). Furthermore, females with a regular estrous cycle had attenuated aggregate rhythms in clock gene expression in the PFC compared with noncycling females. This suggests that gonadal hormones may modulate the expression of the molecular clock. PMID:26271538

  1. Clock gene evolution: seasonal timing, phylogenetic signal, or functional constraint?

    PubMed

    Krabbenhoft, Trevor J; Turner, Thomas F

    2014-01-01

    Genetic determinants of seasonal reproduction are not fully understood but may be important predictors of organism responses to climate change. We used a comparative approach to study the evolution of seasonal timing within a fish community in a natural common garden setting. We tested the hypothesis that allelic length variation in the PolyQ domain of a circadian rhythm gene, Clock1a, corresponded to interspecific differences in seasonal reproductive timing across 5 native and 1 introduced cyprinid fishes (n = 425 individuals) that co-occur in the Rio Grande, NM, USA. Most common allele lengths were longer in native species that initiated reproduction earlier (Spearman's r = -0.70, P = 0.23). Clock1a allele length exhibited strong phylogenetic signal and earlier spawners were evolutionarily derived. Aside from length variation in Clock1a, all other amino acids were identical across native species, suggesting functional constraint over evolutionary time. Interestingly, the endangered Rio Grande silvery minnow (Hybognathus amarus) exhibited less allelic variation in Clock1a and observed heterozygosity was 2- to 6-fold lower than the 5 other (nonimperiled) species. Reduced genetic variation in this functionally important gene may impede this species' capacity to respond to ongoing environmental change. PMID:24558102

  2. Food entrains clock genes but not metabolic genes in the liver of suprachiasmatic nucleus lesioned rats.

    PubMed

    Sabath, Elizabeth; Salgado-Delgado, Roberto; Guerrero-Vargas, Natali N; Guzman-Ruiz, Mara A; del Carmen Basualdo, Maria; Escobar, Carolina; Buijs, Ruud M

    2014-08-25

    Hepatic circadian transcription, considered to be driven by the liver clock, is largely influenced by food even uncoupling it from the suprachiasmatic nucleus (SCN). In SCN lesioned rats (SCNx) we determined the influence of a physiological feeding schedule on the entrainment of clock and clock-controlled (CCG) genes in the liver. We show that clock genes and the CCG Rev-erbα and peroxisome proliferator-activated receptor alpha (PPARα) in food-scheduled intact and SCNx have a robust diurnal differential expression persisting after a 24h fast. However, hepatic nicotinamide phosphoribosyl transferase (Nampt) shows time dependent changes that are lost in intact animals under fasting; moreover, it is unresponsive to the nutrient status in SCNx, indicating a poor reliance on liver clock genes and highlighting the relevance of SCN-derived signals for its metabolic status-related expression. PMID:24983496

  3. Circadian and ultradian rhythms of clock gene expression in the suprachiasmatic nucleus of freely moving mice

    PubMed Central

    Ono, Daisuke; Honma, Ken-ichi; Honma, Sato

    2015-01-01

    In mammals, the temporal order of physiology and behavior is primarily regulated by the circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). Rhythms are generated in cells by an auto-regulatory transcription/translation feedback loop, composed of several clock genes and their protein products. Taking advantage of bioluminescence reporters, we have succeeded in continuously monitoring the expression of clock gene reporters Per1-luc, PER2::LUC and Bmal1-ELuc in the SCN of freely moving mice for up to 3 weeks in constant darkness. Bioluminescence emitted from the SCN was collected with an implanted plastic optical fiber which was connected to a cooled photomultiplier tube. We found robust circadian rhythms in the clock gene expression, the phase-relation of which were the same as those observed ex vivo. The circadian rhythms were superimposed by episodic bursts which had ultradian periods of approximately 3.0 h. Episodic bursts often accompanied activity bouts, but stoichiometric as well as temporal analyses revealed no causality between them. Clock gene expression in the SCN in vivo is regulated by the circadian pacemaker and ultradian rhythms of unknown origin. PMID:26194231

  4. Clock genes, intestinal transport and plasma lipid homeostasis.

    PubMed

    Hussain, M Mahmood; Pan, Xiaoyue

    2009-05-01

    Light and food are two major environmental factors that impact daily life. Light entrainment is centrally controlled by suprachiasmatic nuclei of the hypothalamus. Food entrainment might require cooperation between the intestine and dorsomedial hypothalamus. Clock genes that are essential for light entrainment also play a part in food entrainment. Understanding the role of clock genes in the entrainment of intestinal functions, as well as in gut-brain communication during food entrainment, will enhance our understanding of gastrointestinal and metabolic disorders. This review highlights recent studies examining light- and food-entrained regulation of plasma lipids and of various intestinal activities and offers insight into the role of the intestine in food entrainment. PMID:19349191

  5. Functional circadian clock genes are essential for the overwintering diapause of the Northern house mosquito, Culex pipiens

    PubMed Central

    Meuti, Megan E.; Stone, Mary; Ikeno, Tomoko; Denlinger, David L.

    2015-01-01

    The short day lengths of late summer are used to program the overwintering adult diapause (dormancy) of the Northern house mosquito, Culex pipiens. Here, we investigated the role of clock genes in initiating this diapause and asked whether the circadian cycling of clock gene expression persists during diapause. We provide evidence that the major circadian clock genes continue to cycle throughout diapause and after diapause has been terminated. RNA interference (RNAi) was used to knock down the core circadian clock genes and to then assess the impact of the various clock genes on the ability of females to enter diapause. RNAi directed against negative circadian regulators (period, timeless and cryptochrome2) caused females that were reared under diapause-inducing, short day conditions to avert diapause. In contrast, knocking down the circadian-associated gene pigment dispersing factor caused females that were reared under diapause-averting, long day conditions to enter a diapause-like state. Our results implicate the circadian clock in the initiation of diapause in C. pipiens. PMID:25653422

  6. Altered circadian clock gene expression in patients with schizophrenia.

    PubMed

    Johansson, Anne-Sofie; Owe-Larsson, Björn; Hetta, Jerker; Lundkvist, Gabriella B

    2016-07-01

    Impaired circadian rhythmicity has been reported in several psychiatric disorders. Schizophrenia is commonly associated with aberrant sleep-wake cycles and insomnia. It is not known if schizophrenia is associated with disturbances in molecular rhythmicity. We cultured fibroblasts from skin samples obtained from patients with chronic schizophrenia and from healthy controls, respectively, and analyzed the circadian expression during 48h of the clock genes CLOCK, BMAL1, PER1, PER2, CRY1, CRY2, REV-ERBα and DBP. In fibroblasts obtained from patients with chronic schizophrenia, we found a loss of rhythmic expression of CRY1 and PER2 compared to cells from healthy controls. We also estimated the sleep quality in these patients and found that most of them suffered from poor sleep in comparison with the healthy controls. In another patient sample, we analyzed mononuclear blood cells from patients with schizophrenia experiencing their first episode of psychosis, and found decreased expression of CLOCK, PER2 and CRY1 compared to blood cells from healthy controls. These novel findings show disturbances in the molecular clock in schizophrenia and have important implications in our understanding of the aberrant rhythms reported in this disease. PMID:27132483

  7. Modeling the zebrafish segmentation clock's gene regulatory network constrained by expression data suggests evolutionary transitions between oscillating and nonoscillating transcription.

    PubMed

    Schwendinger-Schreck, Jamie; Kang, Yuan; Holley, Scott A

    2014-06-01

    During segmentation of vertebrate embryos, somites form in accordance with a periodic pattern established by the segmentation clock. In the zebrafish (Danio rerio), the segmentation clock includes six hairy/enhancer of split-related (her/hes) genes, five of which oscillate due to negative autofeedback. The nonoscillating gene hes6 forms the hub of a network of 10 Her/Hes protein dimers, which includes 7 DNA-binding dimers and 4 weak or non-DNA-binding dimers. The balance of dimer species is critical for segmentation clock function, and loss-of-function studies suggest that the her genes have both unique and redundant functions within the clock. However, the precise regulatory interactions underlying the negative feedback loop are unknown. Here, we combine quantitative experimental data, in silico modeling, and a global optimization algorithm to identify a gene regulatory network (GRN) designed to fit measured transcriptional responses to gene knockdown. Surprisingly, we find that hes6, the clock gene that does not oscillate, responds to negative feedback. Consistent with prior in silico analyses, we find that variation in transcription, translation, and degradation rates can mediate the gain and loss of oscillatory behavior for genes regulated by negative feedback. Extending our study, we found that transcription of the nonoscillating Fgf pathway gene sef responds to her/hes perturbation similarly to oscillating her genes. These observations suggest a more extensive underlying regulatory similarity between the zebrafish segmentation clock and the mouse and chick segmentation clocks, which exhibit oscillations of her/hes genes as well as numerous other Notch, Fgf, and Wnt pathway genes. PMID:24663100

  8. Clock genes and behavioral responses to light are altered in a mouse model of diabetic retinopathy.

    PubMed

    Lahouaoui, Hasna; Coutanson, Christine; Cooper, Howard M; Bennis, Mohamed; Dkhissi-Benyahya, Ouria

    2014-01-01

    There is increasing evidence that melanopsin-expressing ganglion cells (ipRGCs) are altered in retinal pathologies. Using a streptozotocin-induced (STZ) model of diabetes, we investigated the impact of diabetic retinopathy on non-visual functions by analyzing ipRGCs morphology and light-induced c-Fos and Period 1-2 clock genes in the central clock (SCN). The ability of STZ-diabetic mice to entrain to light was challenged by exposure animals to 1) successive light/dark (LD) cycle of decreasing or increasing light intensities during the light phase and 2) 6-h advance of the LD cycle. Our results show that diabetes induces morphological changes of ipRGCs, including soma swelling and dendritic varicosities, with no reduction in their total number, associated with decreased c-Fos and clock genes induction by light in the SCN at 12 weeks post-onset of diabetes. In addition, STZ-diabetic mice exhibited a reduction of overall locomotor activity, a decrease of circadian sensitivity to light at low intensities, and a delay in the time to re-entrain after a phase advance of the LD cycle. These novel findings demonstrate that diabetes alters clock genes and behavioral responses of the circadian timing system to light and suggest that diabetic patients may show an increased propensity for circadian disturbances, in particular when they are exposed to chronobiological challenges. PMID:25006976

  9. Osmotic stress at the barley root affects expression of circadian clock genes in the shoot.

    PubMed

    Habte, Ermias; Müller, Lukas M; Shtaya, Munqez; Davis, Seth J; von Korff, Maria

    2014-06-01

    The circadian clock is an important timing system that controls physiological responses to abiotic stresses in plants. However, there is little information on the effects of the clock on stress adaptation in important crops, like barley. In addition, we do not know how osmotic stress perceived at the roots affect the shoot circadian clock. Barley genotypes, carrying natural variation at the photoperiod response and clock genes Ppd-H1 and HvELF3, were grown under control and osmotic stress conditions to record changes in the diurnal expression of clock and stress-response genes and in physiological traits. Variation at HvELF3 affected the expression phase and shape of clock and stress-response genes, while variation at Ppd-H1 only affected the expression levels of stress genes. Osmotic stress up-regulated expression of clock and stress-response genes and advanced their expression peaks. Clock genes controlled the expression of stress-response genes, but had minor effects on gas exchange and leaf transpiration. This study demonstrated that osmotic stress at the barley root altered clock gene expression in the shoot and acted as a spatial input signal into the clock. Unlike in Arabidopsis, barley primary assimilation was less controlled by the clock and more responsive to environmental perturbations, such as osmotic stress. PMID:24895755

  10. Deletion of Rictor in brain and fat alters peripheral clock gene expression and increases blood pressure.

    PubMed

    Drägert, Katja; Bhattacharya, Indranil; Pellegrini, Giovanni; Seebeck, Petra; Azzi, Abdelhalim; Brown, Steven A; Georgiopoulou, Stavroula; Held, Ulrike; Blyszczuk, Przemyslaw; Arras, Margarete; Humar, Rok; Hall, Michael N; Battegay, Edouard; Haas, Elvira

    2015-08-01

    The mammalian target of rapamycin complex 2 (mTORC2) contains the essential protein RICTOR and is activated by growth factors. mTORC2 in adipose tissue contributes to the regulation of glucose and lipid metabolism. In the perivascular adipose tissue, mTORC2 ensures normal vascular reactivity by controlling expression of inflammatory molecules. To assess whether RICTOR/mTORC2 contributes to blood pressure regulation, we applied a radiotelemetry approach in control and Rictor knockout (Rictor(aP2KO)) mice generated using adipocyte protein-2 gene promoter-driven CRE recombinase expression to delete Rictor. The 24-hour mean arterial pressure was increased in Rictor(aP2KO) mice, and the physiological decline in mean arterial pressure during the dark period was impaired. In parallel, heart rate and locomotor activity were elevated during the dark period with a pattern similar to blood pressure changes. This phenotype was associated with mild cardiomyocyte hypertrophy, decreased cardiac natriuretic peptides, and their receptor expression in adipocytes. Moreover, clock gene expression was reduced or phase-shifted in perivascular adipose tissue. No differences in clock gene expression were observed in the master clock suprachiasmatic nucleus, although Rictor gene expression was also lower in brain of Rictor(aP2KO) mice. Thus, this study highlights the importance of RICTOR/mTORC2 for interactions between vasculature, adipocytes, and brain to tune physiological outcomes, such as blood pressure and locomotor activity. PMID:26101345

  11. Regulation of intestinal lipid absorption by clock genes.

    PubMed

    Hussain, M Mahmood

    2014-01-01

    Plasma levels of triacylglycerols and diacylglycerols, the lipoproteins that transport them, and proteins involved in their absorption from the intestinal lumen fluctuate in a circadian manner. These changes are likely controlled by clock genes expressed in the intestine that are probably synchronized by neuronal and humoral signals from the suprachiasmatic nuclei, which constitute a master clock entrained by light signals from the eyes and from the environment, e.g., food availability. Acute changes in circadian rhythms--e.g., due to nonsynchronous work schedules or a transcontinental flight--may trigger intestinal discomfort. Chronic disruptions in circadian control mechanisms may predispose the individual to irritable bowel syndrome, gastroesophageal reflux disease, and peptic ulcer disease. A more detailed understanding of the molecular mechanisms underlying temporal changes in intestinal activity might allow us to identify novel targets for developing therapeutic approaches to these disorders. PMID:25033063

  12. Low Variation in the Polymorphic Clock Gene Poly-Q Region Despite Population Genetic Structure across Barn Swallow (Hirundo rustica) Populations

    PubMed Central

    Dor, Roi; Lovette, Irby J.; Safran, Rebecca J.; Billerman, Shawn M.; Huber, Gernot H.; Vortman, Yoni; Lotem, Arnon; McGowan, Andrew; Evans, Matthew R.; Cooper, Caren B.; Winkler, David W.

    2011-01-01

    Recent studies of several species have reported a latitudinal cline in the circadian clock gene, Clock, which influences rhythms in both physiology and behavior. Latitudinal variation in this gene may hence reflect local adaptation to seasonal variation. In some bird populations, there is also an among-individual association between Clock poly-Q genotype and clutch initiation date and incubation period. We examined Clock poly-Q allele variation in the Barn Swallow (Hirundo rustica), a species with a cosmopolitan geographic distribution and considerable variation in life-history traits that may be influenced by the circadian clock. We genotyped Barn Swallows from five populations (from three subspecies) and compared variation at the Clock locus to that at microsatellite loci and mitochondrial DNA (mtDNA). We found very low variation in the Clock poly-Q region, as >96% of individuals were homozygous, and the two other alleles at this locus were globally rare. Genetic differentiation based on the Clock poly-Q locus was not correlated with genetic differentiation based on either microsatellite loci or mtDNA sequences. Our results show that high diversity in Clock poly-Q is not general across avian species. The low Clock variation in the background of heterogeneity in microsatellite and mtDNA loci in Barn Swallows may be an outcome of stabilizing selection on the Clock locus. PMID:22216124

  13. Codon usage affects the structure and function of the Drosophila circadian clock protein PERIOD.

    PubMed

    Fu, Jingjing; Murphy, Katherine A; Zhou, Mian; Li, Ying H; Lam, Vu H; Tabuloc, Christine A; Chiu, Joanna C; Liu, Yi

    2016-08-01

    Codon usage bias is a universal feature of all genomes, but its in vivo biological functions in animal systems are not clear. To investigate the in vivo role of codon usage in animals, we took advantage of the sensitivity and robustness of the Drosophila circadian system. By codon-optimizing parts of Drosophila period (dper), a core clock gene that encodes a critical component of the circadian oscillator, we showed that dper codon usage is important for circadian clock function. Codon optimization of dper resulted in conformational changes of the dPER protein, altered dPER phosphorylation profile and stability, and impaired dPER function in the circadian negative feedback loop, which manifests into changes in molecular rhythmicity and abnormal circadian behavioral output. This study provides an in vivo example that demonstrates the role of codon usage in determining protein structure and function in an animal system. These results suggest a universal mechanism in eukaryotes that uses a codon usage "code" within genetic codons to regulate cotranslational protein folding. PMID:27542830

  14. Lithium differentially affects clock gene expression in serum-shocked NIH-3T3 cells.

    PubMed

    Osland, Teresa M; Fernø, Johan; Håvik, Bjarte; Heuch, Ivar; Ruoff, Peter; Lærum, Ole Didrik; Steen, Vidar M

    2011-07-01

    Bipolar disorder has been associated with disturbances in circadian rhythms. Lithium is frequently used in the long-term treatment of bipolar disorder, and has been shown to prolong such rhythms in animals and humans. To examine whether lithium affects the expression of genes regulating the circadian clock, cultured NIH-3T3 cells were synchronized by serum-shocking, and the relative expression of the clock genes Period1 (Per1), Period2 (Per2), Period3 (Per3), Cryptochrome1 (Cry1), Cryptochrome2 (Cry2), Brain and muscle aryl hydrocarbon nuclear translocator-like 1 (Bmal1), Circadian locomotor output cycles kaput (Clock), Rev-Erb-α (Nr1d1), RAR-related orphan receptor α (Ror-α), Glycogen synthase kinase-3β (Gsk-3β), Casein kinase 1-ε (CK1-ε; Csnk1ε), E4 binding protein 4 (E4BP4; Nfil-3) and albumin D-binding protein (Dbp) was examined for three consecutive days in the presence of lithium (20 mM) or vehicle (20 mM NaCl). We found that lithium significantly increased the expression of Per2 and Cry1, whereas Per3, Cry2, Bmal1, E4BP4 and Rev-Erb-α expression was reduced. We also found that lithium prolonged the period of Per2. Taken together, these effects on clock gene expression may be relevant for the effects of lithium on biological rhythms and could also give new leads to further explore its mood-stabilizing actions in the treatment of bipolar disorder. PMID:20837565

  15. Regulation of clock-controlled genes in mammals.

    PubMed

    Bozek, Katarzyna; Relógio, Angela; Kielbasa, Szymon M; Heine, Markus; Dame, Christof; Kramer, Achim; Herzel, Hanspeter

    2009-01-01

    The complexity of tissue- and day time-specific regulation of thousands of clock-controlled genes (CCGs) suggests that many regulatory mechanisms contribute to the transcriptional output of the circadian clock. We aim to predict these mechanisms using a large scale promoter analysis of CCGs.Our study is based on a meta-analysis of DNA-array data from rodent tissues. We searched in the promoter regions of 2065 CCGs for highly overrepresented transcription factor binding sites. In order to compensate the relatively high GC-content of CCG promoters, a novel background model to avoid a bias towards GC-rich motifs was employed. We found that many of the transcription factors with overrepresented binding sites in CCG promoters exhibit themselves circadian rhythms. Among the predicted factors are known regulators such as CLOCKratioBMAL1, DBP, HLF, E4BP4, CREB, RORalpha and the recently described regulators HSF1, STAT3, SP1 and HNF-4alpha. As additional promising candidates of circadian transcriptional regulators PAX-4, C/EBP, EVI-1, IRF, E2F, AP-1, HIF-1 and NF-Y were identified. Moreover, GC-rich motifs (SP1, EGR, ZF5, AP-2, WT1, NRF-1) and AT-rich motifs (MEF-2, HMGIY, HNF-1, OCT-1) are significantly overrepresented in promoter regions of CCGs. Putative tissue-specific binding sites such as HNF-3 for liver, NKX2.5 for heart or Myogenin for skeletal muscle were found. The regulation of the erythropoietin (Epo) gene was analysed, which exhibits many binding sites for circadian regulators. We provide experimental evidence for its circadian regulated expression in the adult murine kidney. Basing on a comprehensive literature search we integrate our predictions into a regulatory network of core clock and clock-controlled genes. Our large scale analysis of the CCG promoters reveals the complexity and extensiveness of the circadian regulation in mammals. Results of this study point to connections of the circadian clock to other functional systems including metabolism

  16. EGR1 regulates hepatic clock gene amplitude by activating Per1 transcription

    PubMed Central

    Tao, Weiwei; Wu, Jing; Zhang, Qian; Lai, Shan-Shan; Jiang, Shan; Jiang, Chen; Xu, Ying; Xue, Bin; Du, Jie; Li, Chao-Jun

    2015-01-01

    The mammalian clock system is composed of a master clock and peripheral clocks. At the molecular level, the rhythm-generating mechanism is controlled by a molecular clock composed of positive and negative feedback loops. However, the underlying mechanisms for molecular clock regulation that affect circadian clock function remain unclear. Here, we show that Egr1 (early growth response 1), an early growth response gene, is expressed in mouse liver in a circadian manner. Consistently, Egr1 is transactivated by the CLOCK/BMAL1 heterodimer through a conserved E-box response element. In hepatocytes, EGR1 regulates the transcription of several core clock genes, including Bmal1, Per1, Per2, Rev-erbα and Rev-erbβ, and the rhythm amplitude of their expression is dependent on EGR1’s transcriptional function. Further mechanistic studies indicated that EGR1 binds to the proximal region of the Per1 promoter to activate its transcription directly. When the peripheral clock is altered by light or feeding behavior transposition in Egr1-deficient mice, the expression phase of hepatic clock genes shifts normally, but the amplitude is also altered. Our data reveal a critical role for EGR1 in the regulation of hepatic clock circuitry, which may contribute to the rhythm stability of peripheral clock oscillators. PMID:26471974

  17. Deep RNA profiling identified CLOCK and molecular clock genes as pathophysiological signatures in collagen VI myopathy.

    PubMed

    Scotton, Chiara; Bovolenta, Matteo; Schwartz, Elena; Falzarano, Maria Sofia; Martoni, Elena; Passarelli, Chiara; Armaroli, Annarita; Osman, Hana; Rodolico, Carmelo; Messina, Sonia; Pegoraro, Elena; D'Amico, Adele; Bertini, Enrico; Gualandi, Francesca; Neri, Marcella; Selvatici, Rita; Boffi, Patrizia; Maioli, Maria Antonietta; Lochmüller, Hanns; Straub, Volker; Bushby, Katherine; Castrignanò, Tiziana; Pesole, Graziano; Sabatelli, Patrizia; Merlini, Luciano; Braghetta, Paola; Bonaldo, Paolo; Bernardi, Paolo; Foley, Reghan; Cirak, Sebahattin; Zaharieva, Irina; Muntoni, Francesco; Capitanio, Daniele; Gelfi, Cecilia; Kotelnikova, Ekaterina; Yuryev, Anton; Lebowitz, Michael; Zhang, Xiping; Hodge, Brian A; Esser, Karyn A; Ferlini, Alessandra

    2016-04-15

    Collagen VI myopathies are genetic disorders caused by mutations in collagen 6 A1, A2 and A3 genes, ranging from the severe Ullrich congenital muscular dystrophy to the milder Bethlem myopathy, which is recapitulated by collagen-VI-null (Col6a1(-/-)) mice. Abnormalities in mitochondria and autophagic pathway have been proposed as pathogenic causes of collagen VI myopathies, but the link between collagen VI defects and these metabolic circuits remains unknown. To unravel the expression profiling perturbation in muscles with collagen VI myopathies, we performed a deep RNA profiling in both Col6a1(-/-)mice and patients with collagen VI pathology. The interactome map identified common pathways suggesting a previously undetected connection between circadian genes and collagen VI pathology. Intriguingly, Bmal1(-/-)(also known as Arntl) mice, a well-characterized model displaying arrhythmic circadian rhythms, showed profound deregulation of the collagen VI pathway and of autophagy-related genes. The involvement of circadian rhythms in collagen VI myopathies is new and links autophagy and mitochondrial abnormalities. It also opens new avenues for therapies of hereditary myopathies to modulate the molecular clock or potential gene-environment interactions that might modify muscle damage pathogenesis. PMID:26945058

  18. period-1 encodes an ATP-dependent RNA helicase that influences nutritional compensation of the Neurospora circadian clock

    PubMed Central

    Emerson, Jillian M.; Bartholomai, Bradley M.; Ringelberg, Carol S.; Baker, Scott E.; Loros, Jennifer J.; Dunlap, Jay C.

    2015-01-01

    Mutants in the period-1 (prd-1) gene, characterized by a recessive allele, display a reduced growth rate and period lengthening of the developmental cycle controlled by the circadian clock. We refined the genetic location of prd-1 and used whole genome sequencing to find the mutation defining it, confirming the identity of prd-1 by rescuing the mutant circadian phenotype via transformation. PRD-1 is an RNA helicase whose orthologs, DDX5 [DEAD (Asp-Glu-Ala-Asp) Box Helicase 5] and DDX17 in humans and DBP2 (Dead Box Protein 2) in yeast, are implicated in various processes, including transcriptional regulation, elongation, and termination, ribosome biogenesis, and mRNA decay. Although prd-1 mutants display a long period (∼25 h) circadian developmental cycle, they interestingly display a WT period when the core circadian oscillator is tracked using a frq-luciferase transcriptional fusion under conditions of limiting nutritional carbon; the core oscillator in the prd-1 mutant strain runs with a long period under glucose-sufficient conditions. Thus, PRD-1 clearly impacts the circadian oscillator and is not only part of a metabolic oscillator ancillary to the core clock. PRD-1 is an essential protein, and its expression is neither light-regulated nor clock-regulated. However, it is transiently induced by glucose; in the presence of sufficient glucose, PRD-1 is in the nucleus until glucose runs out, which elicits its disappearance from the nucleus. Because circadian period length is carbon concentration-dependent, prd-1 may be formally viewed as a clock mutant with defective nutritional compensation of circadian period length. PMID:26647184

  19. period-1 encodes an ATP-dependent RNA helicase that influences nutritional compensation of the Neurospora circadian clock

    SciTech Connect

    Emerson, Jillian M.; Bartholomai, Bradley M.; Ringelberg, Carol; Baker, Scott E.; Loros, Jennifer J.; Dunlap, Jay C.

    2015-12-22

    Mutants in the period-1 (prd-1) gene, characterized by a recessive allele, display a reduced growth rate and period lengthening of the developmental cycle controlled by the circadian clock. We refined the genetic location of prd-1 and used whole genome sequencing to find the mutation defining it, confirming the identity of prd-1 by rescuing the mutant circadian phenotype via transformation. PRD-1 is an RNA helicase whose orthologs, DDX5 and DDX17 in humans and Dbp2p in yeast, are implicated in various processes including transcriptional regulation, elongation, and termination, 23 ribosome biogenesis, and RNA decay. Although prdi-1smutantssiois an ATP-dependent RNA helicase, member of a sub-family display a long period (~25 hrs) circadian developmental cycle, they interestingly display a wild type period when the core circadian oscillator is tracked using a frq-luciferase transcriptional fusion under conditions of limiting nutritional carbon; the core oscillator runs with a long period under glucose-sufficient conditions. Thus PRD-1 clearly impacts the circadian oscillator and is not only part of a metabolic oscillator ancillary to the core clock. PRD-1 is an essential protein and its expression is neither light-regulated nor clock-regulated. However, it is transiently induced by glucose; in the presence of sufficient glucose PRD-1 is in the nucleus until glucose runs out which elicits its disappearance from the nucleus. Because circadian period length is carbon concentration-dependent, prd­-1 may be formally viewed as clock mutant with defective nutritional compensation of circadian period length.

  20. Reciprocity Between Robustness of Period and Plasticity of Phase in Biological Clocks

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Tetsuhiro S.; Kaneko, Kunihiko

    2015-11-01

    Circadian clocks exhibit the robustness of period and plasticity of phase against environmental changes such as temperature and nutrient conditions. Thus far, however, it is unclear how both are simultaneously achieved. By investigating distinct models of circadian clocks, we demonstrate reciprocity between robustness and plasticity: higher robustness in the period implies higher plasticity in the phase, where changes in period and in phase follow a linear relationship with a negative coefficient. The robustness of period is achieved by the adaptation on the limit cycle via a concentration change of a buffer molecule, whose temporal change leads to a phase shift following a shift of the limit-cycle orbit in phase space. Generality of reciprocity in clocks with the adaptation mechanism is confirmed with theoretical analysis of simple models, while biological significance is discussed.

  1. The clock gene cryptochrome of Bactrocera cucurbitae (Diptera: Tephritidae) in strains with different mating times.

    PubMed

    Fuchikawa, T; Sanada, S; Nishio, R; Matsumoto, A; Matsuyama, T; Yamagishi, M; Tomioka, K; Tanimura, T; Miyatake, T

    2010-04-01

    Differences in mating time between populations can give rise to premating reproductive isolation. Tephritid fruit flies exhibit large variation in mating time among intra- or inter-specific populations. We previously cloned the clock gene period from two strains of melon fly, Bactrocera cucurbitae; in one the individuals mate early during the day, whereas in the other the individuals mate later. These strains were originally established by divergent artificial selection for developmental time, 'short' and 'long', with early and late mating times, respectively. The deduced amino acid sequences of PERIOD proteins for these two strains were reported to be identical. Here we cloned another clock gene cryptochrome (cry) from the two strains, and found two stable amino acid substitutions in the strains. In addition, the allele frequency at the two polymorphic sites of cry gene correlated with the circadian locomotor period (tau) across strains, whereas the expression pattern of cry mRNA in the heads of flies taken from the short strain significantly differed from that from the long strain. These findings suggest that variation in the cry gene is related to differences in the circadian behaviour in the two strains, thus implying that the cry gene may have an important role in reproductive isolation. PMID:20010960

  2. Clock gene expression in adult primate suprachiasmatic nuclei and adrenal: is the adrenal a peripheral clock responsive to melatonin?

    PubMed

    Valenzuela, F J; Torres-Farfan, C; Richter, H G; Mendez, N; Campino, C; Torrealba, F; Valenzuela, G J; Serón-Ferré, M

    2008-04-01

    The circadian production of glucocorticoids involves the concerted action of several factors that eventually allow an adequate adaptation to the environment. Circadian rhythms are controlled by the circadian timing system that comprises peripheral oscillators and a central rhythm generator located in the suprachiasmatic nucleus (SCN) of the hypothalamus, driven by the self-regulatory interaction of a set of proteins encoded by genes named clock genes. Here we describe the phase relationship between the SCN and adrenal gland for the expression of selected core clock transcripts (Per-2, Bmal-1) in the adult capuchin monkey, a New World, diurnal nonhuman primate. In the SCN we found a higher expression of Bmal-1 during the h of darkness (2000-0200 h) and Per-2 during daytime h (1400 h). The adrenal gland expressed clock genes in oscillatory fashion, with higher values for Bmal-1 during the day (1400-2000 h), whereas Per-2 was higher at nighttime (about 0200 h), resulting in a 9- to 12-h antiphase pattern. In the adrenal gland, the oscillation of clock genes was accompanied by rhythmic expression of a functional output, the steroidogenic enzyme 3beta-hydroxysteroid dehydrogenase. Furthermore, we show that adrenal explants maintained oscillatory expression of Per-2 and Bmal-1 for at least 36 h in culture. The acrophase of both transcripts, but not its overall expression along the incubation, was blunted by 100 nm melatonin. Altogether, these results demonstrate oscillation of clock genes in the SCN and adrenal gland of a diurnal primate and support an oscillation of clock genes in the adrenal gland that may be modulated by the neurohormone melatonin. PMID:18187542

  3. Mutation at the circadian clock gene EARLY MATURITY 8 adapts domesticated barley (Hordeum vulgare) to short growing seasons

    PubMed Central

    Faure, Sebastien; Turner, Adrian S.; Gruszka, Damian; Christodoulou, Vangelis; Davis, Seth J.; von Korff, Maria; Laurie, David A.

    2012-01-01

    The circadian clock is an autonomous oscillator that produces endogenous biological rhythms with a period of about 24 h. This clock allows organisms to coordinate their metabolism and development with predicted daily and seasonal changes of the environment. In plants, circadian rhythms contribute to both evolutionary fitness and agricultural productivity. Nevertheless, we show that commercial barley varieties bred for short growing seasons by use of early maturity 8 (eam8) mutations, also termed mat-a, are severely compromised in clock gene expression and clock outputs. We identified EAM8 as a barley ortholog of the Arabidopsis thaliana circadian clock regulator EARLY FLOWERING3 (ELF3) and demonstrate that eam8 accelerates the transition from vegetative to reproductive growth and inflorescence development. We propose that eam8 was selected as barley cultivation moved to high-latitude short-season environments in Europe because it allowed rapid flowering in genetic backgrounds that contained a previously selected late-flowering mutation of the photoperiod response gene Ppd-H1. We show that eam8 mutants have increased expression of the floral activator HvFT1, which is independent of allelic variation at Ppd-H1. The selection of independent eam8 mutations shows that this strategy facilitates short growth-season adaptation and expansion of the geographic range of barley, despite the pronounced clock defect. PMID:22566625

  4. Circadian rhythms of female mating activity governed by clock genes in Drosophila

    PubMed Central

    Sakai, Takaomi; Ishida, Norio

    2001-01-01

    The physiological and behavioral activities of many animals are restricted to specific times of the day. The daily fluctuation in the mating activity of some insects is controlled by an endogenous clock, but the genetic mechanism that controls it remains unknown. Here we demonstrate that wild-type Drosophila melanogaster display a robust circadian rhythm in the mating activity, and that these rhythms are abolished in period- or timeless-null mutant flies (per01 and tim01). Circadian rhythms were lost when rhythm mutant females were paired with wild-type males, demonstrating that female mating activity is governed by clock genes. Furthermore, we detected an antiphasic relationship in the circadian rhythms of mating activity between D. melanogaster and its sibling species Drosophila simulans. Female- and species-specific circadian rhythms in the mating activity of Drosophila seem to cause reproductive isolation. PMID:11470898

  5. Clock circadian regulator (CLOCK) gene network expression patterns in bovine adipose, liver, and mammary gland at 3 time points during the transition from pregnancy into lactation.

    PubMed

    Wang, M; Zhou, Z; Khan, M J; Gao, J; Loor, J J

    2015-07-01

    The transition from late gestation to early lactation is the most critical phase of the lactation cycle for mammals. Research in rodents has revealed changes in the clock circadian regulator (CLOCK) gene network expression around parturition. However, their expression profiles and putative functions during the periparturient period in ruminants remain to be determined. The present study aimed to investigate the expression pattern of the CLOCK network and selected metabolic genes simultaneously in mammary gland (MG), liver (LIV), and subcutaneous adipose tissue (AT). Seven dairy cows were biopsied at -10 (±2), 7, and 21 d relative to parturition. A day × tissue interaction was observed for ARNTL, CRY1, and PER2 due to upregulation at 7 and 21 d postpartum, with their expression being greater in AT and MG compared with LIV. No interaction was detected for CLOCK, CRY2, PER1, and PER3. In general, the expression of NPAS2, NR1D1, NR2F2, ALAS1, FECH, FBXW11, CCRN4L, PPARA, PPARGC1A, and FGF21 was lower at -10 d but increased postpartum in all tissues. The interaction detected for CSNK1D was associated with increased expression postpartum in AT and MG but not LIV. The interaction detected for CPT1A was due to upregulation in AT and LIV postpartum without a change in MG. In contrast, the interaction for PPARG was due to upregulation in AT and MG postpartum but a downregulation in LIV. Leptin was barely detectable in LIV, but there was an interaction effect in AT and MG associated with upregulation postpartum in MG and downregulation in AT. Together, these results suggest that the control of metabolic adaptations in LIV, MG, and AT around parturition might be partly regulated through the CLOCK gene network. Although the present study did not specifically address rhythmic control of tissue metabolism via the CLOCK gene network, the difference in expression of genes studied among tissues confirms that the behavior of circadian-controlled metabolic genes around parturition

  6. The circadian clock-associated gene zea mays gigantea1 affects maize developmental transitions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The circadian clock is the internal timing mechanism that allows plants to make developmental decisions in accordance with environmental conditions. The genes of the maize circadian clock are not well defined. Gigantea (gi) genes are conserved across flowering plants, including maize. In model plant...

  7. Catabolic cytokines disrupt the circadian clock and the expression of clock-controlled genes in cartilage via an NFкB-dependent pathway

    PubMed Central

    Guo, B.; Yang, N.; Borysiewicz, E.; Dudek, M.; Williams, J.L.; Li, J.; Maywood, E.S.; Adamson, A.; Hastings, M.H.; Bateman, J.F.; White, M.R.H.; Boot-Handford, R.P.; Meng, Q.J.

    2015-01-01

    Summary Objective To define how the catabolic cytokines (Interleukin 1 (IL-1) and tumor necrosis factor alpha (TNFα)) affect the circadian clock mechanism and the expression of clock-controlled catabolic genes within cartilage, and to identify the downstream pathways linking the cytokines to the molecular clock within chondrocytes. Methods Ex vivo cartilage explants were isolated from the Cry1-luc or PER2::LUC clock reporter mice. Clock gene dynamics were monitored in real-time by bioluminescence photon counting. Gene expression changes were studied by qRT-PCR. Functional luc assays were used to study the function of the core Clock/BMAL1 complex in SW-1353 cells. NFкB pathway inhibitor and fluorescence live-imaging of cartilage were performed to study the underlying mechanisms. Results Exposure to IL-1β severely disrupted circadian gene expression rhythms in cartilage. This effect was reversed by an anti-inflammatory drug dexamethasone, but not by other clock synchronizing agents. Circadian disruption mediated by IL-1β was accompanied by disregulated expression of endogenous clock genes and clock-controlled catabolic pathways. Mechanistically, NFкB signalling was involved in the effect of IL-1β on the cartilage clock in part through functional interference with the core Clock/BMAL1 complex. In contrast, TNFα had little impact on the circadian rhythm and clock gene expression in cartilage. Conclusion In our experimental system (young healthy mouse cartilage), we demonstrate that IL-1β (but not TNFα) abolishes circadian rhythms in Cry1-luc and PER2::LUC gene expression. These data implicate disruption of the chondrocyte clock as a novel aspect of the catabolic responses of cartilage to pro-inflammatory cytokines, and provide an additional mechanism for how chronic joint inflammation may contribute to osteoarthritis (OA). PMID:26521744

  8. Saturn's Ionospheric Clock(s): A Concept for Generating and Maintaining Saturn's Observed Magnetospheric Periodicities

    NASA Astrophysics Data System (ADS)

    Mitchell, D. G.; Brandt, P. C.; Ukhorskiy, A. Y.

    2010-12-01

    Saturn’s 10.X hour periodicity, observed throughout the magnetosphere, remains a mystery. It has been observed in many regions, modulating many phenomena. During the Cassini mission most observations have shown a period at about 10.8 hours, expressed in Saturn kilometric radiation from the high latitude auroral zone, in magnetic field components (both equatorial and high latitude) from 3 to 12 Rs, in current sheet encounters in the outer magnetosphere and magnetotail, in energetic neutral atom emission from the equatorial magnetosphere, and in plasma and energetic particles throughout the magnetosphere. More recently, various authors have shown at least two dominant periods expressed (in SKR and in magnetic field components), with slightly different values in the southern and northern hemispheres. The cause of this behavior is still not accounted for. Although loosely associated with Saturn’s rotation, the variability in the period precludes a direct connection with Saturn’s interior (e.g., a magnetic anomaly). Other candidates that have been discussed by others are an ionospheric source (conductivity anomaly), a perturbation in the cold plasma circulation pattern, a magnetospheric cam, asymmetric ring current particle pressure, and/or a natural frequency of the magnetosphere (cavity mode or traveling wave front of some sort). In this paper we present a concept that derives its energy from the subcorotating cold, dense plasma (which exhibits a rotation period on the order of 13 to 14 hours throughout L-shells between ~3 and 20), but is triggered by a process linked with the ionosphere. Key components of the model include significant slippage between the ionosphere and the magnetosphere (with the ionosphere rotating at the expressed period in each hemisphere, only slightly more slowly than the planet interior), subcorotating cold dense plasma with a source in the inner magnetosphere, predominantly radial transport of the cold dense plasma in the rotational

  9. Diurnal Preference Predicts Phase Differences in Expression of Human Peripheral Circadian Clock Genes

    PubMed Central

    Ferrante, Andrew; Gellerman, David; Ay, Ahmet; Woods, Kerri Pruitt; Filipowicz, Allan Michael; Jain, Kriti; Bearden, Neil

    2015-01-01

    Background: Circadian rhythms play an integral role in human behavior, physiology and health. Individual differences in daily rhythms (chronotypes) can affect individual sleep-wake cycles, activity patterns and behavioral choices. Diurnal preference, the tendency towards morningness or eveningness among individuals, has been associated with interpersonal variation in circadian clock-related output measures, including body temperature, melatonin levels and clock gene mRNA in blood, oral mucosa, and dermal fibroblast cell cultures. Methods: Here we report gene expression data from two principal clock genes sampled from hair follicle cells, a peripheral circadian clock. Hair follicle cells from fourteen individuals of extreme morning or evening chronotype were sampled at three time points. RNA was extracted and quantitative PCR assays were used to measure mRNA expression patterns of two clock genes, Per3 and Nr1d2. Results: We found significant differences in clock gene expression over time between chronotype groups, independent of gender or age of participants. Extreme evening chronotypes have a delay in phase of circadian clock gene oscillation relative to extreme morning types. Variation in the molecular clockwork of chronotype groups represents nearly three-hour phase differences (Per3: 2.61 hours; Nr1d2: 3.08 hours, both: 2.86) in circadian oscillations of these clock genes. Conclusions: The measurement of gene expression from hair follicles at three time points allows for a direct, efficient method of estimating phase shifts of a peripheral circadian clock in real-life conditions. The robust phase differences in temporal expression of clock genes associated with diurnal preferences provide the framework for further studies of the molecular mechanisms and gene-by-environment interactions underlying chronotype-specific behavioral phenomena, including social jetlag. PMID:27103930

  10. Dynamics of the circadian clock protein PERIOD2 in living cells.

    PubMed

    Öllinger, Rupert; Korge, Sandra; Korte, Thomas; Koller, Barbara; Herrmann, Andreas; Kramer, Achim

    2014-10-01

    In mammals, circadian rhythms are generated by delayed negative feedback, in which period (PER1-PER3) and cryptochrome (CRY1, CRY2) proteins gradually accumulate in the nucleus to suppress the transcription of their own genes. Although the importance of nuclear import and export signals for the subcellular localization of clock proteins is well established, little is known about the dynamics of these processes as well as their importance for the generation of circadian rhythms. We show by pharmacological perturbations of oscillating cells that nuclear import and export are of crucial importance for the circadian period. Live-cell fluorescence microscopy revealed that nuclear import of the key circadian protein PER2 is fast and further accelerated by CRY1. Moreover, PER2 nuclear import is crucially dependent on a specific nuclear-receptor-binding motif in PER2 that also mediates nuclear immobility. Nuclear export, however, is relatively slow, supporting a model of PER2 nuclear accumulation by rapid import, slow export and substantial nuclear degradation. PMID:25074809

  11. Natural selection against a circadian clock gene mutation in mice

    PubMed Central

    Spoelstra, Kamiel; Wikelski, Martin; Daan, Serge; Loudon, Andrew S. I.; Hau, Michaela

    2016-01-01

    Circadian rhythms with an endogenous period close to or equal to the natural light–dark cycle are considered evolutionarily adaptive (“circadian resonance hypothesis”). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural conditions for any eukaryotic organism. We tested this hypothesis in mice bearing a short-period mutation in the enzyme casein kinase 1ε (tau mutation), which accelerates free-running circadian cycles. We compared daily activity (feeding) rhythms, survivorship, and reproduction in six replicate populations in outdoor experimental enclosures, established with wild-type, heterozygous, and homozygous mice in a Mendelian ratio. In the release cohort, survival was reduced in the homozygote mutant mice, revealing strong selection against short-period genotypes. Over the course of 14 mo, the relative frequency of the tau allele dropped from initial parity to 20%. Adult survival and recruitment of juveniles into the population contributed approximately equally to the selection for wild-type alleles. The expression of activity during daytime varied throughout the experiment and was significantly increased by the tau mutation. The strong selection against the short-period tau allele observed here contrasts with earlier studies showing absence of selection against a Period 2 (Per2) mutation, which disrupts internal clock function, but does not change period length. These findings are consistent with, and predicted by the theory that resonance of the circadian system plays an important role in individual fitness. PMID:26715747

  12. Natural selection against a circadian clock gene mutation in mice.

    PubMed

    Spoelstra, Kamiel; Wikelski, Martin; Daan, Serge; Loudon, Andrew S I; Hau, Michaela

    2016-01-19

    Circadian rhythms with an endogenous period close to or equal to the natural light-dark cycle are considered evolutionarily adaptive ("circadian resonance hypothesis"). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural conditions for any eukaryotic organism. We tested this hypothesis in mice bearing a short-period mutation in the enzyme casein kinase 1ε (tau mutation), which accelerates free-running circadian cycles. We compared daily activity (feeding) rhythms, survivorship, and reproduction in six replicate populations in outdoor experimental enclosures, established with wild-type, heterozygous, and homozygous mice in a Mendelian ratio. In the release cohort, survival was reduced in the homozygote mutant mice, revealing strong selection against short-period genotypes. Over the course of 14 mo, the relative frequency of the tau allele dropped from initial parity to 20%. Adult survival and recruitment of juveniles into the population contributed approximately equally to the selection for wild-type alleles. The expression of activity during daytime varied throughout the experiment and was significantly increased by the tau mutation. The strong selection against the short-period tau allele observed here contrasts with earlier studies showing absence of selection against a Period 2 (Per2) mutation, which disrupts internal clock function, but does not change period length. These findings are consistent with, and predicted by the theory that resonance of the circadian system plays an important role in individual fitness. PMID:26715747

  13. Clock Gene Bmal1 Modulates Human Cartilage Gene Expression by Crosstalk With Sirt1.

    PubMed

    Yang, Wei; Kang, Xiaomin; Liu, Jiali; Li, Huixia; Ma, Zhengmin; Jin, Xinxin; Qian, Zhuang; Xie, Tianping; Qin, Na; Feng, Dongxu; Pan, Wenjie; Chen, Qian; Sun, Hongzhi; Wu, Shufang

    2016-08-01

    The critical regulation of the peripheral circadian gene implicated in osteoarthritis (OA) has been recently recognized; however, the causative role and clinical potential of the peripheral circadian rhythm attributable to such effects remain elusive. The purpose of this study was to elucidate the role of a circadian gene Bmal1 in human cartilage and pathophysiology of osteoarthritis. In our present study, the mRNA and protein levels of circadian rhythm genes, including nicotinamide adenine dinucleotide oxidase (NAD(+)) and sirtuin 1 (Sirt1), in human knee articular cartilage were determined. In OA cartilage, the levels of both Bmal1 and NAD(+) decreased significantly, which resulted in the inhibition of nicotinamide phosphoribosyltransferase activity and Sirt1 expression. Furthermore, the knockdown of Bmal1 was sufficient to decrease the level of NAD(+) and aggravate OA-like gene expression changes under the stimulation of IL-1β. The overexpression of Bmal1 relieved the alteration induced by IL-1β, which was consistent with the effect of the inhibition of Rev-Erbα (known as NR1D1, nuclear receptor subfamily 1, group D). On the other hand, the transfection of Sirt1 small interfering RNA not only resulted in a reduction of the protein expression of Bmal1 and a moderate increase of period 2 (per2) and Rev-Erbα but also further exacerbated the survival of cells and the expression of cartilage matrix-degrading enzymes induced by IL-1β. Overexpression of Sirt1 restored the metabolic imbalance of chondrocytes caused by IL-1β. These observations suggest that Bmal1 is a key clock gene to involve in cartilage homeostasis mediated through sirt1 and that manipulating circadian rhythm gene expression implicates an innovative strategy to develop novel therapeutic agents against cartilage diseases. PMID:27253997

  14. Common features in diverse insect clocks.

    PubMed

    Numata, Hideharu; Miyazaki, Yosuke; Ikeno, Tomoko

    2015-01-01

    This review describes common features among diverse biological clocks in insects, including circadian, circatidal, circalunar/circasemilunar, and circannual clocks. These clocks control various behaviors, physiological functions, and developmental events, enabling adaptation to periodic environmental changes. Circadian clocks also function in time-compensation for celestial navigation and in the measurement of day or night length for photoperiodism. Phase response curves for such clocks reported thus far exhibit close similarities; specifically, the circannual clock in Anthrenus verbasci shows striking similarity to circadian clocks in its phase response. It is suggested that diverse biological clocks share physiological properties in their phase responses irrespective of period length. Molecular and physiological mechanisms are best understood for the optic-lobe and mid-brain circadian clocks, although there is no direct evidence that these clocks are involved in rhythmic phenomena other than circadian rhythms in daily events. Circadian clocks have also been localized in peripheral tissues, and research on their role in various rhythmic phenomena has been started. Although clock genes have been identified as controllers of circadian rhythms in daily events, some of these genes have also been shown to be involved in photoperiodism and possibly in time-compensated celestial navigation. In contrast, there is no experimental evidence indicating that any known clock gene is involved in biological clocks other than circadian clocks. PMID:26605055

  15. Identification, Characterization, and Diel Pattern of Expression of Canonical Clock Genes in Nephrops norvegicus (Crustacea: Decapoda) Eyestalk.

    PubMed

    Sbragaglia, Valerio; Lamanna, Francesco; M Mat, Audrey; Rotllant, Guiomar; Joly, Silvia; Ketmaier, Valerio; de la Iglesia, Horacio O; Aguzzi, Jacopo

    2015-01-01

    The Norway lobster, Nephrops norvegicus, is a burrowing decapod with a rhythmic burrow emergence (24 h) governed by the circadian system. It is an important resource for European fisheries and its behavior deeply affects its availability. The current knowledge of Nephrops circadian biology is phenomenological as it is currently the case for almost all crustaceans. In attempt to elucidate the putative molecular mechanisms underlying circadian gene regulation in Nephrops, we used a transcriptomics approach on cDNA extracted from the eyestalk, a structure playing a crucial role in controlling behavior of decapods. We studied 14 male lobsters under 12-12 light-darkness blue light cycle. We used the Hiseq 2000 Illumina platform to sequence two eyestalk libraries (under light and darkness conditions) obtaining about 90 millions 100-bp paired-end reads. Trinity was used for the de novo reconstruction of transcriptomes; the size at which half of all assembled bases reside in contigs (N50) was equal to 1796 (light) and 2055 (darkness). We found a list of candidate clock genes and focused our attention on canonical ones: timeless, period, clock and bmal1. The cloning of assembled fragments validated Trinity outputs. The putative Nephrops clock genes showed high levels of identity (blastx on NCBI) with known crustacean clock gene homologs such as Eurydice pulchra (period: 47%, timeless: 59%, bmal1: 79%) and Macrobrachium rosenbergii (clock: 100%). We also found a vertebrate-like cryptochrome 2. RT-qPCR showed that only timeless had a robust diel pattern of expression. Our data are in accordance with the current knowledge of the crustacean circadian clock, reinforcing the idea that the molecular clockwork of this group shows some differences with the established model in Drosophila melanogaster. PMID:26524198

  16. Identification, Characterization, and Diel Pattern of Expression of Canonical Clock Genes in Nephrops norvegicus (Crustacea: Decapoda) Eyestalk

    PubMed Central

    Sbragaglia, Valerio; Lamanna, Francesco; M. Mat, Audrey; Rotllant, Guiomar; Joly, Silvia; Ketmaier, Valerio; de la Iglesia, Horacio O.; Aguzzi, Jacopo

    2015-01-01

    The Norway lobster, Nephrops norvegicus, is a burrowing decapod with a rhythmic burrow emergence (24 h) governed by the circadian system. It is an important resource for European fisheries and its behavior deeply affects its availability. The current knowledge of Nephrops circadian biology is phenomenological as it is currently the case for almost all crustaceans. In attempt to elucidate the putative molecular mechanisms underlying circadian gene regulation in Nephrops, we used a transcriptomics approach on cDNA extracted from the eyestalk, a structure playing a crucial role in controlling behavior of decapods. We studied 14 male lobsters under 12–12 light-darkness blue light cycle. We used the Hiseq 2000 Illumina platform to sequence two eyestalk libraries (under light and darkness conditions) obtaining about 90 millions 100-bp paired-end reads. Trinity was used for the de novo reconstruction of transcriptomes; the size at which half of all assembled bases reside in contigs (N50) was equal to 1796 (light) and 2055 (darkness). We found a list of candidate clock genes and focused our attention on canonical ones: timeless, period, clock and bmal1. The cloning of assembled fragments validated Trinity outputs. The putative Nephrops clock genes showed high levels of identity (blastx on NCBI) with known crustacean clock gene homologs such as Eurydice pulchra (period: 47%, timeless: 59%, bmal1: 79%) and Macrobrachium rosenbergii (clock: 100%). We also found a vertebrate-like cryptochrome 2. RT-qPCR showed that only timeless had a robust diel pattern of expression. Our data are in accordance with the current knowledge of the crustacean circadian clock, reinforcing the idea that the molecular clockwork of this group shows some differences with the established model in Drosophila melanogaster. PMID:26524198

  17. Molecular clock of HIV-1 envelope genes under early immune selection

    DOE PAGESBeta

    Park, Sung Yong; Love, Tanzy M. T.; Perelson, Alan S.; Mack, Wendy J.; Lee, Ha Youn

    2016-06-01

    Here, the molecular clock hypothesis that genes or proteins evolve at a constant rate is a key tool to reveal phylogenetic relationships among species. Using the molecular clock, we can trace an infection back to transmission using HIV-1 sequences from a single time point. Whether or not a strict molecular clock applies to HIV-1’s early evolution in the presence of immune selection has not yet been fully examined.

  18. Cycling of clock genes entrained to the solar rhythm enables plants to tell time: data from arabidopsis

    PubMed Central

    Yeang, Hoong-Yeet

    2015-01-01

    Background and Aims An endogenous rhythm synchronized to dawn cannot time photosynthesis-linked genes to peak consistently at noon since the interval between sunrise and noon changes seasonally. In this study, a solar clock model that circumvents this limitation is proposed using two daily timing references synchronized to noon and midnight. Other rhythmic genes that are not directly linked to photosynthesis, and which peak at other times, also find an adaptive advantage in entrainment to the solar rhythm. Methods Fourteen datasets extracted from three published papers were used in a meta-analysis to examine the cyclic behaviour of the Arabidopsis thaliana photosynthesis-related gene CAB2 and the clock oscillator genes TOC1 and LHY in T cycles and N–H cycles. Key Results Changes in the rhythms of CAB2, TOC1 and LHY in plants subjected to non-24-h light:dark cycles matched the hypothesized changes in their behaviour as predicted by the solar clock model, thus validating it. The analysis further showed that TOC1 expression peaked ∼5·5 h after mid-day, CAB2 peaked close to noon, while LHY peaked ∼7·5 h after midnight, regardless of the cycle period, the photoperiod or the light:dark period ratio. The solar clock model correctly predicted the zeitgeber timing of these genes under 11 different lighting regimes comprising combinations of seven light periods, nine dark periods, four cycle periods and four light:dark period ratios. In short cycles that terminated before LHY could be expressed, the solar clock correctly predicted zeitgeber timing of its expression in the following cycle. Conclusions Regulation of gene phases by the solar clock enables the plant to tell the time, by which means a large number of genes are regulated. This facilitates the initiation of gene expression even before the arrival of sunrise, sunset or noon, thus allowing the plant to ‘anticipate’ dawn, dusk or mid-day respectively, independently of the photoperiod. PMID:26070640

  19. Palmitate Inhibits SIRT1-Dependent BMAL1/CLOCK Interaction and Disrupts Circadian Gene Oscillations in Hepatocytes

    PubMed Central

    Tong, Xin; Zhang, Deqiang; Arthurs, Blake; Li, Pei; Durudogan, Leigh; Gupta, Neil; Yin, Lei

    2015-01-01

    Elevated levels of serum saturated fatty acid palmitate have been shown to promote insulin resistance, increase cellular ROS production, and trigger cell apoptosis in hepatocytes during the development of obesity. However, it remains unclear whether palmitate directly impacts the circadian clock in hepatocytes, which coordinates nutritional inputs and hormonal signaling with downstream metabolic outputs. Here we presented evidence that the molecular clock is a novel target of palmitate in hepatocytes. Palmitate exposure at low dose inhibits the molecular clock activity and suppresses the cyclic expression of circadian targets including Dbp, Nr1d1 and Per2 in hepatocytes. Palmitate treatment does not seem to alter localization or reduce protein expression of BMAL1 and CLOCK, the two core components of the molecular clock in hepatocytes. Instead, palmitate destabilizes the protein-protein interaction between BMAL1-CLOCK in a dose and time-dependent manner. Furthermore, we showed that SIRT1 activators could reverse the inhibitory action of palmitate on BMAL1-CLOCK interaction and the clock gene expression, whereas inhibitors of NAD synthesis mimic the palmitate effects on the clock function. In summary, our findings demonstrated that palmitate inhibits the clock function by suppressing SIRT1 function in hepatocytes. PMID:26075729

  20. Circadian Rhythm Genes CLOCK and PER3 Polymorphisms and Morning Gastric Motility in Humans

    PubMed Central

    Yamaguchi, Mitsue; Kotani, Kazuhiko; Tsuzaki, Kokoro; Takagi, Ayaka; Motokubota, Naoko; Komai, Naho; Sakane, Naoki; Moritani, Toshio; Nagai, Narumi

    2015-01-01

    Background Clock genes regulate circadian rhythm and are involved in various physiological processes, including digestion. We therefore investigated the association between the CLOCK 3111T/C single nucleotide polymorphism and the Period3 (PER3) variable-number tandem-repeat polymorphism (either 4 or 5 repeats 54 nt in length) with morning gastric motility. Methods Lifestyle questionnaires and anthropometric measurements were performed with 173 female volunteers (mean age, 19.4 years). Gastric motility, evaluated by electrogastrography (EGG), blood pressure, and heart rate levels were measured at 8:30 a.m. after an overnight fast. For gastric motility, the spectral powers (% normal power) and dominant frequency (DF, peak of the power spectrum) of the EGG were evaluated. The CLOCK and PER3 polymorphisms were determined by polymerase chain reaction (PCR) restriction fragment length polymorphism analysis. Results Subjects with the CLOCK C allele (T/C or C/C genotypes: n = 59) showed a significantly lower DF (mean, 2.56 cpm) than those with the T/T genotype (n = 114, 2.81 cpm, P < 0.05). Subjects with the longer PER3 allele (PER34/5 or PER35/5 genotypes: n = 65) also showed a significantly lower DF (2.55 cpm) than those with the shorter PER34/4 genotype (n = 108, 2.83 cpm, P < 0.05). Furthermore, subjects with both the T/C or C/C and PER34/5 or PER35/5 genotypes showed a significantly lower DF (2.43 cpm, P < 0.05) than subjects with other combinations of the alleles (T/T and PER34/4 genotype, T/C or C/C and PER34/4 genotypes, and T/T and PER34/5 or PER35/5 genotypes). Conclusions These results suggest that minor polymorphisms of the circadian rhythm genes CLOCK and PER3 may be associated with poor morning gastric motility, and may have a combinatorial effect. The present findings may offer a new viewpoint on the role of circadian rhythm genes on the peripheral circadian systems, including the time-keeping function of the gut. PMID:25775462

  1. Flies, clocks and evolution.

    PubMed Central

    Rosato, E; Kyriacou, C P

    2001-01-01

    The negative feedback model for gene regulation of the circadian mechanism is described for the fruitfly, Drosophila melanogaster. The conservation of function of clock molecules is illustrated by comparison with the mammalian circadian system, and the apparent swapping of roles between various canonical clock gene components is highlighted. The role of clock gene duplications and divergence of function is introduced via the timeless gene. The impressive similarities in clock gene regulation between flies and mammals could suggest that variation between more closely related species within insects might be minimal. However, this is not borne out because the expression of clock molecules in the brain of the giant silk moth, Antheraea pernyi, is not easy to reconcile with the negative feedback roles of the period and timeless genes. Variation in clock gene sequences between and within fly species is examined and the role of co-evolution between and within clock molecules is described, particularly with reference to adaptive functions of the circadian phenotype. PMID:11710984

  2. Direct Repression of Evening Genes by CIRCADIAN CLOCK-ASSOCIATED1 in the Arabidopsis Circadian Clock[OPEN

    PubMed Central

    Kamioka, Mari; Takao, Saori; Suzuki, Takamasa; Taki, Kyomi; Higashiyama, Tetsuya; Nakamichi, Norihito

    2016-01-01

    The circadian clock is a biological timekeeping system that provides organisms with the ability to adapt to day-night cycles. Timing of the expression of four members of the Arabidopsis thaliana PSEUDO-RESPONSE REGULATOR (PRR) family is crucial for proper clock function, and transcriptional control of PRRs remains incompletely defined. Here, we demonstrate that direct regulation of PRR5 by CIRCADIAN CLOCK-ASSOCIATED1 (CCA1) determines the repression state of PRR5 in the morning. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) analyses indicated that CCA1 associates with three separate regions upstream of PRR5. CCA1 and its homolog LATE ELONGATED HYPOCOTYL (LHY) suppressed PRR5 promoter activity in a transient assay. The regions bound by CCA1 in the PRR5 promoter gave rhythmic patterns with troughs in the morning, when CCA1 and LHY are at high levels. Furthermore, ChIP-seq revealed that CCA1 associates with at least 449 loci with 863 adjacent genes. Importantly, this gene set contains genes that are repressed but upregulated in cca1 lhy double mutants in the morning. This study shows that direct binding by CCA1 in the morning provides strong repression of PRR5, and repression by CCA1 also temporally regulates an evening-expressed gene set that includes PRR5. PMID:26941090

  3. Circadian clock genes universally control key agricultural traits

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Circadian clocks are endogenous timers that enable plants to synchronize biological processes with daily and seasonal environmental conditions in order to allocate resources during the most beneficial times of day and year. The circadian clock regulates a number of central plant activities, includin...

  4. Diurnal oscillations of soybean circadian clock and drought responsive genes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhythms produced by the endogenous circadian clock play a critical role in allowing plants to respond and adapt to the environment. While there is a well-established regulatory link between the circadian clock and responses to abiotic stress in model plants, little is known of the circadian system i...

  5. The negative transcription factor E4BP4 is associated with circadian clock protein PERIOD2.

    PubMed

    Ohno, Tomoya; Onishi, Yoshiaki; Ishida, Norio

    2007-03-23

    The bZIP transcription factor E4BP4, is a mammalian homologue of vrille that functions as a key negative component of the circadian clock. We have shown that the E4BP4-binding site (B-site) is required in addition to a non-canonical E-box (E2 enhancer) for robust circadian Period2 (Per2) expression in the cell-autonomous clock. While the E2 enhancer and the B-site are closely situated, correlations between each component bound to the E2 enhancer and the B-site remain obscure. Here, we show that E4BP4 interacts with PER2, which represses transcriptional activity via the E-box enhancer. Interaction with PER2 required the carboxyl-terminal region that contains the repression domain of E4BP4. We also found that E4BP4 interacts with CRYPTOCHROME2 (CRY2), a key negative regulator in the mammalian circadian clock. These results suggest that E4BP4 is a component of the negative regulator complex of mammalian circadian clocks. PMID:17274955

  6. Altered dynamics in the circadian oscillation of clock genes in dermal fibroblasts of patients suffering from idiopathic hypersomnia.

    PubMed

    Lippert, Julian; Halfter, Hartmut; Heidbreder, Anna; Röhr, Dominik; Gess, Burkhard; Boentert, Mathias; Osada, Nani; Young, Peter

    2014-01-01

    From single cell organisms to the most complex life forms, the 24-hour circadian rhythm is important for numerous aspects of physiology and behavior such as daily periodic fluctuations in body temperature and sleep-wake cycles. Influenced by environmental cues - mainly by light input -, the central pacemaker in the thalamic suprachiasmatic nuclei (SCN) controls and regulates the internal clock mechanisms which are present in peripheral tissues. In order to correlate modifications in the molecular mechanisms of circadian rhythm with the pathophysiology of idiopathic hypersomnia, this study aimed to investigate the dynamics of the expression of circadian clock genes in dermal fibroblasts of idiopathic hypersomniacs (IH) in comparison to those of healthy controls (HC). Ten clinically and polysomnographically proven IH patients were recruited from the department of sleep medicine of the University Hospital of Muenster. Clinical diagnosis was done by two consecutive polysomnographies (PSG) and Multiple Sleep Latency Test (MSLT). Fourteen clinical healthy volunteers served as control group. Dermal fibroblasts were obtained via punch biopsy and grown in cell culture. The expression of circadian clock genes was investigated by semiquantitative Reverse Transcriptase-PCR qRT-PCR analysis, confirming periodical oscillation of expression of the core circadian clock genes BMAL1, PER1/2 and CRY1/2. The amplitude of the rhythmically expressed BMAL1, PER1 and PER2 was significantly dampened in dermal fibroblasts of IH compared to HC over two circadian periods whereas the overall expression of only the key transcriptional factor BMAL1 was significantly reduced in IH. Our study suggests for the first time an aberrant dynamics in the circadian clock in IH. These findings may serve to better understand some clinical features of the pathophysiology in sleep - wake rhythms in IH. PMID:24454829

  7. RAPID COMMUNICATION: Improving prediction accuracy of GPS satellite clocks with periodic variation behaviour

    NASA Astrophysics Data System (ADS)

    Heo, Youn Jeong; Cho, Jeongho; Heo, Moon Beom

    2010-07-01

    The broadcast ephemeris and IGS ultra-rapid predicted (IGU-P) products are primarily available for use in real-time GPS applications. The IGU orbit precision has been remarkably improved since late 2007, but its clock products have not shown acceptably high-quality prediction performance. One reason for this fact is that satellite atomic clocks in space can be easily influenced by various factors such as temperature and environment and this leads to complicated aspects like periodic variations, which are not sufficiently described by conventional models. A more reliable prediction model is thus proposed in this paper in order to be utilized particularly in describing the periodic variation behaviour satisfactorily. The proposed prediction model for satellite clocks adds cyclic terms to overcome the periodic effects and adopts delay coordinate embedding, which offers the possibility of accessing linear or nonlinear coupling characteristics like satellite behaviour. The simulation results have shown that the proposed prediction model outperforms the IGU-P solutions at least on a daily basis.

  8. Calorie restriction regulates circadian clock gene expression through BMAL1 dependent and independent mechanisms.

    PubMed

    Patel, Sonal A; Velingkaar, Nikkhil; Makwana, Kuldeep; Chaudhari, Amol; Kondratov, Roman

    2016-01-01

    Feeding behavior, metabolism and circadian clocks are interlinked. Calorie restriction (CR) is a feeding paradigm known to extend longevity. We found that CR significantly affected the rhythms in the expression of circadian clock genes in mice on the mRNA and protein levels, suggesting that CR reprograms the clocks both transcriptionally and post-transcriptionally. The effect of CR on gene expression was distinct from the effects of time-restricted feeding or fasting. Furthermore, CR affected the circadian output through up- or down-regulation of the expression of several clock-controlled transcriptional factors and the longevity candidate genes. CR-dependent effects on some clock gene expression were impaired in the liver of mice deficient for BMAL1, suggesting importance of this transcriptional factor for the transcriptional reprogramming of the clock, however, BMAL1- independent mechanisms also exist. We propose that CR recruits biological clocks as a natural mechanism of metabolic optimization under conditions of limited energy resources. PMID:27170536

  9. Calorie restriction regulates circadian clock gene expression through BMAL1 dependent and independent mechanisms

    PubMed Central

    Patel, Sonal A.; Velingkaar, Nikkhil; Makwana, Kuldeep; Chaudhari, Amol; Kondratov, Roman

    2016-01-01

    Feeding behavior, metabolism and circadian clocks are interlinked. Calorie restriction (CR) is a feeding paradigm known to extend longevity. We found that CR significantly affected the rhythms in the expression of circadian clock genes in mice on the mRNA and protein levels, suggesting that CR reprograms the clocks both transcriptionally and post-transcriptionally. The effect of CR on gene expression was distinct from the effects of time-restricted feeding or fasting. Furthermore, CR affected the circadian output through up- or down-regulation of the expression of several clock-controlled transcriptional factors and the longevity candidate genes. CR-dependent effects on some clock gene expression were impaired in the liver of mice deficient for BMAL1, suggesting importance of this transcriptional factor for the transcriptional reprogramming of the clock, however, BMAL1- independent mechanisms also exist. We propose that CR recruits biological clocks as a natural mechanism of metabolic optimization under conditions of limited energy resources. PMID:27170536

  10. Circadian Clock genes Per2 and clock regulate steroid production, cell proliferation, and luteinizing hormone receptor transcription in ovarian granulosa cells

    SciTech Connect

    Shimizu, Takashi; Hirai, Yuko; Murayama, Chiaki; Miyamoto, Akio; Miyazaki, Hitoshi; Miyazaki, Koyomi

    2011-08-19

    Highlights: {yields} Treatment with Per2 and Clock siRNAs decreased the number of granulosa cells and LHr expression. {yields}Per2 siRNA treatment did not stimulate the production of estradiol and expression of P450arom. {yields} Clock siRNA treatment inhibited the production of estradiol and expression of P450arom mRNA. {yields}Per2 and Clock siRNA treatment increased and unchanged, respectively, progesterone production in FSH-treated granulosa cells. {yields} The expression of StAR mRNA was increased by Per2 siRNA and unchanged by Clock siRNA. -- Abstract: Circadian Clock genes are associated with the estrous cycle in female animals. Treatment with Per2 and Clock siRNAs decreased the number of granulosa cells and LHr expression in follicle-stimulating hormone FSH-treated granulosa cells. Per2 siRNA treatment did not stimulate the production of estradiol and expression of P450arom, whereas Clock siRNA treatment inhibited the production of estradiol and expression of P450arom mRNA. Per2 and Clock siRNA treatment increased and unchanged, respectively, progesterone production in FSH-treated granulosa cells. Similarly, expression of StAR mRNA was increased by Per2 siRNA and unchanged by Clock siRNA. Our data provide a new insight that Per2 and Clock have different action on ovarian granulosa cell functions.

  11. α1B-Adrenergic receptor signaling controls circadian expression of Tnfrsf11b by regulating clock genes in osteoblasts

    PubMed Central

    Hirai, Takao; Tanaka, Kenjiro; Togari, Akifumi

    2015-01-01

    ABSTRACT Circadian clocks are endogenous and biological oscillations that occur with a period of <24 h. In mammals, the central circadian pacemaker is localized in the suprachiasmatic nucleus (SCN) and is linked to peripheral tissues through neural and hormonal signals. In the present study, we investigated the physiological function of the molecular clock on bone remodeling. The results of loss-of-function and gain-of-function experiments both indicated that the rhythmic expression of Tnfrsf11b, which encodes osteoprotegerin (OPG), was regulated by Bmal1 in MC3T3-E1 cells. We also showed that REV-ERBα negatively regulated Tnfrsf11b as well as Bmal1 in MC3T3-E1 cells. We systematically investigated the relationship between the sympathetic nervous system and the circadian clock in osteoblasts. The administration of phenylephrine, a nonspecific α1-adrenergic receptor (AR) agonist, stimulated the expression of Tnfrsf11b, whereas the genetic ablation of α1B-AR signaling led to the alteration of Tnfrsf11b expression concomitant with Bmal1 and Per2 in bone. Thus, this study demonstrated that the circadian regulation of Tnfrsf11b was regulated by the clock genes encoding REV-ERBα (Nr1d1) and Bmal1 (Bmal1, also known as Arntl), which are components of the core loop of the circadian clock in osteoblasts. PMID:26453621

  12. The core clock gene Per1 phases molecular and electrical circadian rhythms in SCN neurons

    PubMed Central

    Jones, Jeff R.

    2016-01-01

    The brain’s biological clock, the suprachiasmatic nucleus (SCN), exhibits endogenous 24-hour rhythms in gene expression and spontaneous firing rate; however, the functional relationship between these neuronal rhythms is not fully understood. Here, we used a Per1::GFP transgenic mouse line that allows for the simultaneous quantification of molecular clock state and firing rate in SCN neurons to examine the relationship between these key components of the circadian clock. We find that there is a stable, phased relationship between E-box-driven clock gene expression and spontaneous firing rate in SCN neurons and that these relationships are independent of light input onto the system or of GABAA receptor-mediated synaptic activity. Importantly, the concordant phasing of gene and neural rhythms is disrupted in the absence of the homologous clock gene Per1, but persists in the absence of the core clock gene Per2. These results suggest that Per1 plays a unique, non-redundant role in phasing gene expression and firing rate rhythms in SCN neurons to increase the robustness of cellular timekeeping. PMID:27602274

  13. The core clock gene Per1 phases molecular and electrical circadian rhythms in SCN neurons.

    PubMed

    Jones, Jeff R; McMahon, Douglas G

    2016-01-01

    The brain's biological clock, the suprachiasmatic nucleus (SCN), exhibits endogenous 24-hour rhythms in gene expression and spontaneous firing rate; however, the functional relationship between these neuronal rhythms is not fully understood. Here, we used a Per1::GFP transgenic mouse line that allows for the simultaneous quantification of molecular clock state and firing rate in SCN neurons to examine the relationship between these key components of the circadian clock. We find that there is a stable, phased relationship between E-box-driven clock gene expression and spontaneous firing rate in SCN neurons and that these relationships are independent of light input onto the system or of GABAA receptor-mediated synaptic activity. Importantly, the concordant phasing of gene and neural rhythms is disrupted in the absence of the homologous clock gene Per1, but persists in the absence of the core clock gene Per2. These results suggest that Per1 plays a unique, non-redundant role in phasing gene expression and firing rate rhythms in SCN neurons to increase the robustness of cellular timekeeping. PMID:27602274

  14. Altered Clock and Lipid Metabolism-Related Genes in Atherosclerotic Mice Kept with Abnormal Lighting Condition

    PubMed Central

    Zhu, Zhu; Hua, Bingxuan; Shang, Zhanxian; Yuan, Gongsheng; Xu, Lirong; Li, Ermin; Li, Xiaobo; Yan, Zuoqin; Qian, Ruizhe

    2016-01-01

    Background. The risk of atherosclerosis is elevated in abnormal lipid metabolism and circadian rhythm disorder. We investigated whether abnormal lighting condition would have influenced the circadian expression of clock genes and clock-controlled lipid metabolism-related genes in ApoE-KO mice. Methods. A mouse model of atherosclerosis with circadian clock genes expression disorder was established using ApoE-KO mice (ApoE-KO LD/DL mice) by altering exposure to light. C57 BL/6J mice (C57 mice) and ApoE-KO mice (ApoE-KO mice) exposed to normal day and night and normal diet served as control mice. According to zeitgeber time samples were acquired, to test atheromatous plaque formation, serum lipids levels and rhythmicity, clock genes, and lipid metabolism-related genes along with Sirtuin 1 (Sirt1) levels and rhythmicity. Results. Atherosclerosis plaques were formed in the aortic arch of ApoE-KO LD/DL mice. The serum lipids levels and oscillations in ApoE-KO LD/DL mice were altered, along with the levels and diurnal oscillations of circadian genes, lipid metabolism-associated genes, and Sirt1 compared with the control mice. Conclusions. Abnormal exposure to light aggravated plaque formation and exacerbated disorders of serum lipids and clock genes, lipid metabolism genes and Sirt1 levels, and circadian oscillation.

  15. In vivo imaging of clock gene expression in multiple tissues of freely moving mice.

    PubMed

    Hamada, Toshiyuki; Sutherland, Kenneth; Ishikawa, Masayori; Miyamoto, Naoki; Honma, Sato; Shirato, Hiroki; Honma, Ken-Ichi

    2016-01-01

    Clock genes are expressed throughout the body, although how they oscillate in unrestrained animals is not known. Here, we show an in vivo imaging technique that enables long-term simultaneous imaging of multiple tissues. We use dual-focal 3D tracking and signal-intensity calibration to follow gene expression in a target area. We measure circadian rhythms of clock genes in the olfactory bulb, right and left ears and cortices, and the skin. In addition, the kinetic relationship between gene expression and physiological responses to experimental cues is monitored. Under stable conditions gene expression is in phase in all tissues. In response to a long-duration light pulse, the olfactory bulb shifts faster than other tissues. In Cry1(-/-) Cry2(-/-) arrhythmic mice circadian oscillation is absent in all tissues. Thus, our system successfully tracks circadian rhythms in clock genes in multiple tissues in unrestrained mice. PMID:27285820

  16. Chronotype and sleep quality as a subphenotype in association studies of clock genes in mood disorders.

    PubMed

    Dmitrzak-Węglarz, Monika; Pawlak, Joanna; Wiłkość, Monika; Miechowicz, Izabela; Maciukiewicz, Małgorzata; Ciarkowska, Wanda; Zaremba, Dorota; Hauser, Joanna

    2016-01-01

    Genetic background and clinical picture of mood disorders (MD) are complex and may depend on many genes and their potential interactions as well as environmental factors. Therefore, clinical variations, or endophenotypes, were suggested for association studies. The aim of the study was to investigate association between the chronotype (CH) and quality of sleep characteristics with polymorphisms CLOCK, ARNTL, TIMELESS and PER3 genes in MD. We included a total sample of 111 inpatients and 126 healthy controls. To assess CH we applied Morningness-Eveningness Questionnaire (MEQ). Additionally, we defined the quality and patterns of sleep using The Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS). We applied Kruskal-Wallis test to determine associations. The main positive findings refer to associations between selected polymorphisms and: 1) chronotype with the ARNTL gene (rs11824092 and rs1481892) and the CLOCK (rs1268271) 2) sleep duration with the CLOCK gene (rs3805148) and the TIM gene (rs2291739) 3) daytime dysfunction with the PER3 gene (rs228727, rs228642, rs10864315) 4) subjective sleep quality with the ARNTL gene (rs11824092, rs1982350) 5) sleep disturbances with the ARNTL gene (rs11600996) We also found the significant epistatic interactions between polymorphism of the PER3 gene (rs2640909) & the CLOCK gene (rs11932595) and following sleep quality variables: sleep duration, habitual sleep efficiency and subjective sleep quality. The present study suggests a putative role of the analyzed clock genes polymorphisms in chronotype in the control group and in sleep quality disturbances in the course of MD. The results indicate that PSQI variables can be used to refine phenotype in association studies of clock genes in MD. PMID:27102916

  17. Role of the clock gene Rev-erbα in metabolism and in the endocrine pancreas.

    PubMed

    Vieira, E; Merino, B; Quesada, I

    2015-09-01

    Several hormones are regulated by circadian rhythms to adjust the metabolism to the light/dark cycles and feeding/activity patterns throughout the day. Circadian rhythms are mainly governed by the central clock located in the suprachiasmatic nucleus but also by clocks present in peripheral organs, like the endocrine pancreas. Plasma glucose levels and the main pancreatic hormones insulin and glucagon also exhibit daily variations. Alterations in circadian rhythms are associated with metabolic disturbances and pathologies such as obesity and diabetes. The molecular components of central and peripheral clocks and their regulatory mechanisms are well established. Among the different clock genes, Rev-erbα is considered one of the key links between circadian rhythms and metabolism. Rev-erbα is a critical part of a negative feedback loop in the core circadian clock and modulates the clock oscillatory properties. In addition, Rev-erbα plays an important role in the regulation of lipid and glucose metabolism, thermogenesis, adipocyte and muscle differentiation as well as mitochondrial function. In the endocrine pancreas, Rev-erbα regulates insulin and glucagon secretion and pancreatic β-cell proliferation. In the present review, we discuss all these subjects and, particularly, the role of the clock gene Rev-erbα in the endocrine pancreas. PMID:26332975

  18. Circadian and Circalunar Clock Interactions in a Marine Annelid

    PubMed Central

    Zantke, Juliane; Ishikawa-Fujiwara, Tomoko; Arboleda, Enrique; Lohs, Claudia; Schipany, Katharina; Hallay, Natalia; Straw, Andrew D.; Todo, Takeshi; Tessmar-Raible, Kristin

    2013-01-01

    Summary Life is controlled by multiple rhythms. Although the interaction of the daily (circadian) clock with environmental stimuli, such as light, is well documented, its relationship to endogenous clocks with other periods is little understood. We establish that the marine worm Platynereis dumerilii possesses endogenous circadian and circalunar (monthly) clocks and characterize their interactions. The RNAs of likely core circadian oscillator genes localize to a distinct nucleus of the worm’s forebrain. The worm’s forebrain also harbors a circalunar clock entrained by nocturnal light. This monthly clock regulates maturation and persists even when circadian clock oscillations are disrupted by the inhibition of casein kinase 1δ/ε. Both circadian and circalunar clocks converge on the regulation of transcript levels. Furthermore, the circalunar clock changes the period and power of circadian behavior, although the period length of the daily transcriptional oscillations remains unaltered. We conclude that a second endogenous noncircadian clock can influence circadian clock function. PMID:24075994

  19. Circadian clock genes are rhythmically expressed in specific segments of the hen oviduct.

    PubMed

    Zhang, Z C; Wang, Y G; Li, L; Yin, H D; Li, D Y; Wang, Y; Zhao, X L; Liu, Y P; Zhu, Q

    2016-07-01

    In animals, core clock genes are expressed in many peripheral tissues throughout the body that contribute to tissue specific temporal regulation including those that comprise the reproductive system. The chicken ovulatory cycle seems to provide an example of a system in which circadian and interval timing mechanisms operate during ovulation-oviposition. However, little is known about the possible role of circadian regulation during egg formation and laying. To this end, we determined the rhythmic expression of several known canonical clock genes and clock controlled genes in the 4 segments of the chicken oviduct (infundibulum, magnum, isthmus, and uterus) taken from the same biological state (laying sequence and oviposition time) using real time RT-PCR. Except for Cry1, the other genes we analyzed were expressed in all 4 segments of the oviduct. Intriguingly, in a daily light-dark cycle, Bmal1, Clock, Per2, Per3, Cry2, and Rev-erbβ have highly significant rhythmic expression in the infundibulum and uterus but not in the magnum and isthmus. These results show that there is spatial specificity in the localization of clock cells in the hen reproductive tract and that peripheral clocks might have a direct role in the infundibulum and uterus where yolk is captured and the eggshell is formed, respectively. PMID:26944979

  20. Sleep loss reduces the DNA-binding of BMAL1, CLOCK, and NPAS2 to specific clock genes in the mouse cerebral cortex.

    PubMed

    Mongrain, Valérie; La Spada, Francesco; Curie, Thomas; Franken, Paul

    2011-01-01

    We have previously demonstrated that clock genes contribute to the homeostatic aspect of sleep regulation. Indeed, mutations in some clock genes modify the markers of sleep homeostasis and an increase in homeostatic sleep drive alters clock gene expression in the forebrain. Here, we investigate a possible mechanism by which sleep deprivation (SD) could alter clock gene expression by quantifying DNA-binding of the core-clock transcription factors CLOCK, NPAS2, and BMAL1 to the cis-regulatory sequences of target clock genes in mice. Using chromatin immunoprecipitation (ChIP), we first showed that, as reported for the liver, DNA-binding of CLOCK and BMAL1 to target clock genes changes in function of time-of-day in the cerebral cortex. Tissue extracts were collected at ZT0 (light onset), -6, -12, and -18, and DNA enrichment of E-box or E'-box containing sequences was measured by qPCR. CLOCK and BMAL1 binding to Cry1, Dbp, Per1, and Per2 depended on time-of-day, with maximum values reached at around ZT6. We then observed that SD, performed between ZT0 and -6, significantly decreased DNA-binding of CLOCK and BMAL1 to Dbp, consistent with the observed decrease in Dbp mRNA levels after SD. The DNA-binding of NPAS2 and BMAL1 to Per2 was also decreased by SD, although SD is known to increase Per2 expression in the cortex. DNA-binding to Per1 and Cry1 was not affected by SD. Our results show that the sleep-wake history can affect the clock molecular machinery directly at the level of chromatin binding thereby altering the cortical expression of Dbp and Per2 and likely other targets. Although the precise dynamics of the relationship between DNA-binding and mRNA expression, especially for Per2, remains elusive, the results also suggest that part of the reported circadian changes in DNA-binding of core clock components in tissues peripheral to the suprachiasmatic nuclei could, in fact, be sleep-wake driven. PMID:22039518

  1. Sleep Loss Reduces the DNA-Binding of BMAL1, CLOCK, and NPAS2 to Specific Clock Genes in the Mouse Cerebral Cortex

    PubMed Central

    Curie, Thomas; Franken, Paul

    2011-01-01

    We have previously demonstrated that clock genes contribute to the homeostatic aspect of sleep regulation. Indeed, mutations in some clock genes modify the markers of sleep homeostasis and an increase in homeostatic sleep drive alters clock gene expression in the forebrain. Here, we investigate a possible mechanism by which sleep deprivation (SD) could alter clock gene expression by quantifying DNA-binding of the core-clock transcription factors CLOCK, NPAS2, and BMAL1 to the cis-regulatory sequences of target clock genes in mice. Using chromatin immunoprecipitation (ChIP), we first showed that, as reported for the liver, DNA-binding of CLOCK and BMAL1 to target clock genes changes in function of time-of-day in the cerebral cortex. Tissue extracts were collected at ZT0 (light onset), −6, −12, and −18, and DNA enrichment of E-box or E'-box containing sequences was measured by qPCR. CLOCK and BMAL1 binding to Cry1, Dbp, Per1, and Per2 depended on time-of-day, with maximum values reached at around ZT6. We then observed that SD, performed between ZT0 and −6, significantly decreased DNA-binding of CLOCK and BMAL1 to Dbp, consistent with the observed decrease in Dbp mRNA levels after SD. The DNA-binding of NPAS2 and BMAL1 to Per2 was also decreased by SD, although SD is known to increase Per2 expression in the cortex. DNA-binding to Per1 and Cry1 was not affected by SD. Our results show that the sleep-wake history can affect the clock molecular machinery directly at the level of chromatin binding thereby altering the cortical expression of Dbp and Per2 and likely other targets. Although the precise dynamics of the relationship between DNA-binding and mRNA expression, especially for Per2, remains elusive, the results also suggest that part of the reported circadian changes in DNA-binding of core clock components in tissues peripheral to the suprachiasmatic nuclei could, in fact, be sleep-wake driven. PMID:22039518

  2. Exploitation of host clock gene machinery by hepatitis viruses B and C

    PubMed Central

    Vinciguerra, Manlio; Mazzoccoli, Gianluigi; Piccoli, Claudia; Tataranni, Tiziana; Andriulli, Angelo; Pazienza, Valerio

    2013-01-01

    Many aspects of cellular physiology display circadian (approximately 24-h) rhythms. Dysfunction of the circadian clock molecular circuitry is associated with human health derangements, including neurodegeneration, increased risk of cancer, cardiovascular diseases and the metabolic syndrome. Viruses triggering hepatitis depend tightly on the host cell synthesis machinery for their own replication, survival and spreading. Recent evidences support a link between the circadian clock circuitry and viruses’ biological cycle within host cells. Currently, in vitro models for chronobiological studies of cells infected with viruses need to be implemented. The establishment of such in vitro models would be helpful to better understand the link between the clock gene machinery and viral replication/viral persistence in order to develop specifically targeted therapeutic regimens. Here we review the recent literature dealing with the interplay between hepatitis B and C viruses and clock genes. PMID:24379614

  3. A robust two-gene oscillator at the core of Ostreococcus tauri circadian clock

    NASA Astrophysics Data System (ADS)

    Morant, Pierre-Emmanuel; Thommen, Quentin; Pfeuty, Benjamin; Vandermoere, Constant; Corellou, Florence; Bouget, François-Yves; Lefranc, Marc

    2010-12-01

    The microscopic green alga Ostreococcus tauri is rapidly emerging as a promising model organism in the green lineage. In particular, recent results by Corellou et al. [Plant Cell 21, 3436 (2009)] and Thommen et al. [PLOS Comput. Biol. 6, e1000990 (2010)] strongly suggest that its circadian clock is a simplified version of Arabidopsis thaliana clock, and that it is architectured so as to be robust to natural daylight fluctuations. In this work, we analyze the time series data from luminescent reporters for the two central clock genes TOC1 and CCA1 and correlate them with microarray data previously analyzed. Our mathematical analysis strongly supports both the existence of a simple two-gene oscillator at the core of Ostreococcus tauri clock and the fact that its dynamics is not affected by light in normal entrainment conditions, a signature of its robustness.

  4. Circadian dysregulation of clock genes: clues to rapid treatments in major depressive disorder.

    PubMed

    Bunney, B G; Li, J Z; Walsh, D M; Stein, R; Vawter, M P; Cartagena, P; Barchas, J D; Schatzberg, A F; Myers, R M; Watson, S J; Akil, H; Bunney, W E

    2015-02-01

    Conventional antidepressants require 2-8 weeks for a full clinical response. In contrast, two rapidly acting antidepressant interventions, low-dose ketamine and sleep deprivation (SD) therapy, act within hours to robustly decrease depressive symptoms in a subgroup of major depressive disorder (MDD) patients. Evidence that MDD may be a circadian-related illness is based, in part, on a large set of clinical data showing that diurnal rhythmicity (sleep, temperature, mood and hormone secretion) is altered during depressive episodes. In a microarray study, we observed widespread changes in cyclic gene expression in six regions of postmortem brain tissue of depressed patients matched with controls for time-of-death (TOD). We screened 12 000 transcripts and observed that the core clock genes, essential for controlling virtually all rhythms in the body, showed robust 24-h sinusoidal expression patterns in six brain regions in control subjects. In MDD patients matched for TOD with controls, the expression patterns of the clock genes in brain were significantly dysregulated. Some of the most robust changes were seen in anterior cingulate (ACC). These findings suggest that in addition to structural abnormalities, lesion studies, and the large body of functional brain imaging studies reporting increased activation in the ACC of depressed patients who respond to a wide range of therapies, there may be a circadian dysregulation in clock gene expression in a subgroup of MDDs. Here, we review human, animal and neuronal cell culture data suggesting that both low-dose ketamine and SD can modulate circadian rhythms. We hypothesize that the rapid antidepressant actions of ketamine and SD may act, in part, to reset abnormal clock genes in MDD to restore and stabilize circadian rhythmicity. Conversely, clinical relapse may reflect a desynchronization of the clock, indicative of a reactivation of abnormal clock gene function. Future work could involve identifying specific small

  5. Circadian dysregulation of clock genes: clues to rapid treatments in major depressive disorder

    PubMed Central

    Bunney, BG; Li, JZ; Walsh, DM; Stein, R; Vawter, MP; Cartagena, P; Barchas, JD; Schatzberg, AF; Myers, RM; Watson, SJ; Akil, H; Bunney, WE

    2016-01-01

    Conventional antidepressants require 2–8 weeks for a full clinical response. In contrast, two rapidly acting antidepressant interventions, low-dose ketamine and sleep deprivation (SD) therapy, act within hours to robustly decrease depressive symptoms in a subgroup of major depressive disorder (MDD) patients. Evidence that MDD may be a circadian-related illness is based, in part, on a large set of clinical data showing that diurnal rhythmicity (sleep, temperature, mood and hormone secretion) is altered during depressive episodes. In a microarray study, we observed widespread changes in cyclic gene expression in six regions of postmortem brain tissue of depressed patients matched with controls for time-of-death (TOD). We screened 12 000 transcripts and observed that the core clock genes, essential for controlling virtually all rhythms in the body, showed robust 24-h sinusoidal expression patterns in six brain regions in control subjects. In MDD patients matched for TOD with controls, the expression patterns of the clock genes in brain were significantly dysregulated. Some of the most robust changes were seen in anterior cingulate (ACC). These findings suggest that in addition to structural abnormalities, lesion studies, and the large body of functional brain imaging studies reporting increased activation in the ACC of depressed patients who respond to a wide range of therapies, there may be a circadian dysregulation in clock gene expression in a subgroup of MDDs. Here, we review human, animal and neuronal cell culture data suggesting that both low-dose ketamine and SD can modulate circadian rhythms. We hypothesize that the rapid antidepressant actions of ketamine and SD may act, in part, to reset abnormal clock genes in MDD to restore and stabilize circadian rhythmicity. Conversely, clinical relapse may reflect a desynchronization of the clock, indicative of a reactivation of abnormal clock gene function. Future work could involve identifying specific small

  6. Circadian Clocks and Metabolism

    PubMed Central

    Marcheva, Biliana; Ramsey, Kathryn M.; Peek, Clara B.; Affinati, Alison; Maury, Eleonore; Bass, Joseph

    2014-01-01

    Circadian clocks maintain periodicity in internal cycles of behavior, physiology, and metabolism, enabling organisms to anticipate the 24-h rotation of the Earth. In mammals, circadian integration of metabolic systems optimizes energy harvesting and utilization across the light/dark cycle. Disruption of clock genes has recently been linked to sleep disorders and to the development of cardiometabolic disease. Conversely, aberrant nutrient signaling affects circadian rhythms of behavior. This chapter reviews the emerging relationship between the molecular clock and metabolic systems and examines evidence that circadian disruption exerts deleterious consequences on human health. PMID:23604478

  7. Long-term effect of systemic RNA interference on circadian clock genes in hemimetabolous insects.

    PubMed

    Uryu, Outa; Kamae, Yuichi; Tomioka, Kenji; Yoshii, Taishi

    2013-04-01

    RNA interference (RNAi) strategy, which enables gene-specific knock-down of transcripts, has been spread across a wide area of insect studies for investigating gene function without regard to model and non-model insects. This technique is of particular benefit to promote molecular studies on non-model insects. However, the optimal conditions for RNAi are still not well understood because of its variable efficiency depending on the species, target genes, and experimental conditions. To apply RNAi technique to long-running experiments such as chronobiological studies, the effects of RNAi have to persist throughout the experiment. In this study, we attempted to determine the optimal concentration of double-stranded RNA (dsRNA) for systemic RNAi and its effective period in two different insect species, the cricket Gryllus bimaculatus and the firebrat Thermobia domestica. In both species, higher concentrations of dsRNA principally yielded a more efficient knock-down of mRNA levels of tested clock genes, although the effect depended on the gene and the species. Surprisingly, the effect of the RNAi reached its maximum effect 1-2 weeks and 1 month after the injection of dsRNA in the crickets and the firebrats, respectively, suggesting a slow but long-term effect of RNAi. Our study provides fundamental information for utilizing RNAi technique in any long-running experiment. PMID:23458340

  8. The frequency gene is required for temperature-dependent regulation of many clock-controlled genes in Neurospora crassa.

    PubMed Central

    Nowrousian, Minou; Duffield, Giles E; Loros, Jennifer J; Dunlap, Jay C

    2003-01-01

    The circadian clock of Neurospora broadly regulates gene expression and is synchronized with the environment through molecular responses to changes in ambient light and temperature. It is generally understood that light entrainment of the clock depends on a functional circadian oscillator comprising the products of the wc-1 and wc-2 genes as well as those of the frq gene (the FRQ/WCC oscillator). However, various models have been advanced to explain temperature regulation. In nature, light and temperature cues reinforce one another such that transitions from dark to light and/or cold to warm set the clock to subjective morning. In some models, the FRQ/WCC circadian oscillator is seen as essential for temperature-entrained clock-controlled output; alternatively, this oscillator is seen exclusively as part of the light pathway mediating entrainment of a cryptic "driving oscillator" that mediates all temperature-entrained rhythmicity, in addition to providing the impetus for circadian oscillations in general. To identify novel clock-controlled genes and to examine these models, we have analyzed gene expression on a broad scale using cDNA microarrays. Between 2.7 and 5.9% of genes were rhythmically expressed with peak expression in the subjective morning. A total of 1.4-1.8% of genes responded consistently to temperature entrainment; all are clock controlled and all required the frq gene for this clock-regulated expression even under temperature-entrainment conditions. These data are consistent with a role for frq in the control of temperature-regulated gene expression in N. crassa and suggest that the circadian feedback loop may also serve as a sensor for small changes in ambient temperature. PMID:12871904

  9. Periodic transition on an axial compressor stator: Incidence and clocking effects. Part 1: Experimental data

    SciTech Connect

    Walker, G.J.; Hughes, J.D.; Solomon, W.J.

    1999-07-01

    Periodic wake-induced transition on the outlet stator of a 1.5-stage axial compressor is examined using hot-film arrays on both the suction and pressure surfaces. The time-mean surface pressure distribution is varied by changing the blade incidence, while the free-stream disturbance field is altered by clocking of the stator relative to an inlet guide vane row. Ensemble-averaged plots of turbulent intermittency and relaxation factor (extent of calmed flow following the passage of a turbulent spot) are presented. These show the strength of periodic wake-induced transition phenomena to be significantly influenced by both incidence and clocking effects. The nature and extent of transition by other modes (natural, bypass, and separated flow transition) are altered accordingly. Leading edge and midchord separation bubbles are affected in a characteristically different manner by changing free-stream periodicity. There are noticeable differences between suction and pressure surface transition behavior, particularly as regards the strength and extent of calming. In Part 2 of this paper, the transition onset observations from the compressor stator are used to evaluate the quasi-steady application of conventional transition correlations to predict unsteady transition onset on the blading of an embedded axial compressor stage.

  10. The period gene and allochronic reproductive isolation in Bactrocera cucurbitae.

    PubMed

    Miyatake, Takahisa; Matsumoto, Akira; Matsuyama, Takashi; Ueda, Hiroki R; Toyosato, Tetsuya; Tanimura, Teiichi

    2002-12-01

    Clock genes that pleiotropically control circadian rhythm and the time of mating may cause allochronic reproductive isolation in the melon fly Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae). Flies with a shorter circadian period (ca. 22 h of locomotor activity rhythm) mated 5 h earlier in the day than those with a longer circadian period (ca. 30 h). Mate-choice tests demonstrated significant pre-mating isolation between populations with short and long circadian periods. Pre-mating isolation did not occur when the mating time was synchronized between the two populations by photoperiodic controls, indicating that reproductive isolation is due to variations in the time of mating and not any unidentified ethological difference between the two populations. We cloned the period (per) gene of B. cucurbitae that is homologous to the per gene in Drosophila. The relative level of per mRNA in the melon fly exhibited a robust daily fluctuation under light : dark conditions. The fluctuation of per expression under dark : dark conditions is closely correlated to the locomotor rhythm in B. cucurbitae. These results suggest that clock genes can cause reproductive isolation via the pleiotropic effect as a change of mating time. PMID:12495490

  11. Genome-Wide Molecular Clock and Horizontal Gene Transfer in Bacterial Evolution

    PubMed Central

    Novichkov, Pavel S.; Omelchenko, Marina V.; Gelfand, Mikhail S.; Mironov, Andrei A.; Wolf, Yuri I.; Koonin, Eugene V.

    2004-01-01

    We describe a simple theoretical framework for identifying orthologous sets of genes that deviate from a clock-like model of evolution. The approach used is based on comparing the evolutionary distances within a set of orthologs to a standard intergenomic distance, which was defined as the median of the distribution of the distances between all one-to-one orthologs. Under the clock-like model, the points on a plot of intergenic distances versus intergenomic distances are expected to fit a straight line. A statistical technique to identify significant deviations from the clock-like behavior is described. For several hundred analyzed orthologous sets representing three well-defined bacterial lineages, the α-Proteobacteria, the γ-Proteobacteria, and the Bacillus-Clostridium group, the clock-like null hypothesis could not be rejected for ∼70% of the sets, whereas the rest showed substantial anomalies. Subsequent detailed phylogenetic analysis of the genes with the strongest deviations indicated that over one-half of these genes probably underwent a distinct form of horizontal gene transfer, xenologous gene displacement, in which a gene is displaced by an ortholog from a different lineage. The remaining deviations from the clock-like model could be explained by lineage-specific acceleration of evolution. The results indicate that although xenologous gene displacement is a major force in bacterial evolution, a significant majority of orthologous gene sets in three major bacterial lineages evolved in accordance with the clock-like model. The approach described here allows rapid detection of deviations from this mode of evolution on the genome scale. PMID:15375139

  12. Daily and seasonal expression of clock genes in the pituitary of the European sea bass (Dicentrarchus labrax).

    PubMed

    Herrero, María Jesús; Lepesant, Julie M J

    2014-11-01

    The expression of select clock genes (clock, bmal, per1, per2, cry1, cry2) was investigated throughout the day and across the four seasons for two consecutive years in the pituitary of adult sea bass (Dicentrarchus labrax). A rhythmic pattern of daily expression was consistently observed in summer and autumn, while arrhythmicity was observed for some clock genes during spring and winter, concomitant with low water temperatures. The expression of clock and bmal showed highest values at the end of the day and during the night, while that of per and cry was mostly antiphasic, with high values during the day. Melatonin affects clock-gene expression in the pituitary of mammals. We therefore sought to test the effect of melatonin on clock-gene expression in the pituitary of sea bass both in vivo and in vitro. Melatonin modestly affected the expression of some clock genes (in particular cry genes) when added to the fish diet or the culture medium of pituitary glands. Our data show that clock genes display rhythmic daily expression in the pituitary of adult sea bass, which are profoundly modified according to the season. We suggest that the effect of photoperiod on clock gene expression may be mediated, at least in part, by melatonin, and that temperature may have a key role adjusting seasonal variations. PMID:25148807

  13. Diabetic retinopathy alters light-induced clock gene expression and dopamine levels in the mouse retina

    PubMed Central

    Lahouaoui, Hasna; Coutanson, Christine; Cooper, Howard M.; Bennis, Mohamed

    2016-01-01

    Purpose Diabetic retinopathy is one of the most common consequences of diabetes that affects millions of working-age adults worldwide and leads to progressive degeneration of the retina, visual loss, and blindness. Diabetes is associated with circadian disruption of the central and peripheral circadian clocks, but the mechanisms responsible for such alterations are unknown. Using a streptozotocin (STZ)-induced model of diabetes, we investigated whether diabetes alters 1) the circadian regulation of clock genes in the retina and in the central clocks, 2) the light response of clock genes in the retina, and/or 3) light-driven retinal dopamine (DA), a major output marker of the retinal clock. Methods To quantify circadian expression of clock and clock-controlled genes, retinas and suprachiasmatic nucleus (SCN) from the same animals were collected every 4 h in circadian conditions, 12 weeks post-diabetes. Induction of Per1, Per2, and c-fos mRNAs was quantified in the retina after the administration of a pulse of monochromatic light (480 nm, 1.17×1014 photons/cm2/s, 15 min) at circadian time 16. Gene expression was assessed with real-time reverse transcription PCR (RT–PCR). Pooled retinas from the control and STZ-diabetic mice were collected 2 h after light ON and light OFF (Zeitgeber time (ZT)2 and ZT14), and DA and its metabolite were analyzed with high-performance liquid chromatography (HPLC). Results We found variable effects of diabetes on the expression of clock genes in the retina and only slight differences in phase and/or amplitude in the SCN. c-fos and Per1 induction by a 480 nm light pulse was abolished in diabetic animals at 12 weeks post-induction of diabetes in comparison with the control mice, suggesting a deficit in light-induced neuronal activation of the retinal clock. Finally, we quantified a 56% reduction in the total number of tyrosine hydroxylase (TH) immunopositive cells, associated with a decrease in DA levels during the subjective day (ZT2

  14. MYC/MIZ1-dependent gene repression inversely coordinates the circadian clock with cell cycle and proliferation

    PubMed Central

    Shostak, Anton; Ruppert, Bianca; Ha, Nati; Bruns, Philipp; Toprak, Umut H.; Lawerenz, Chris; Lichter, Peter; Radlwimmer, Bernhard; Eils, Jürgen; Brors, Benedikt; Radomski, Sylwester; Scholz, Ingrid; Richter, Gesine; Siebert, Reiner; Wagner, Susanne; Haake, Andrea; Richter, Julia; Aukema, Sietse; Ammerpohl, Ole; Lopez, Christina; Nagel, Inga; Vater, Inga; Wagner, Rabea; Borst, Christoph; Haas, Siegfried; Rohde, Marius; Burkhardt, Birgit; Lisfeld, Jasmin; Claviez, Alexander; Dreyling, Martin; Eberth, Sonja; Trümper, Lorenz; Kube, Dieter; Stadler, Christina; Einsele, Hermann; Frickhofen, Norbert; Hansmann, Martin-Leo; Karsch, Dennis; Kneba, Michael; Mantovani-Löffler, Luisa; Staib, Peter; Stilgenbauer, Stephan; Ott, German; Küppers, Ralf; Weniger, Marc; Hummel, Michael; Lenze, Dido; Szczepanowski, Monika; Klapper, Wolfram; Kostezka, Ulrike; Möller, Peter; Rosenwald, Andreas; Leich, Ellen; Pischimariov, Jordan; Binder, Vera; Borkhardt, Arndt; Hezaveh, Kebria; Hoell, Jessica; Rosenstiel, Philip; Schilhabel, Markus; Schreiber, Stefan; Bernhart, Stephan H.; Doose, Gero; Hoffmann, Steve; Kretzmer, Helene; Langenberger, David; Binder, Hans; Hopp, Lydia; Kreuz, Markus; Loeffler, Markus; Rosolowski, Maciej; Korbel, Jan; Sungalee, Stefanie; Stadler, Peter F.; Zenz, Thorsten; Eils, Roland; Schlesner, Matthias; Diernfellner, Axel; Brunner, Michael

    2016-01-01

    The circadian clock and the cell cycle are major cellular systems that organize global physiology in temporal fashion. It seems conceivable that the potentially conflicting programs are coordinated. We show here that overexpression of MYC in U2OS cells attenuates the clock and conversely promotes cell proliferation while downregulation of MYC strengthens the clock and reduces proliferation. Inhibition of the circadian clock is crucially dependent on the formation of repressive complexes of MYC with MIZ1 and subsequent downregulation of the core clock genes BMAL1 (ARNTL), CLOCK and NPAS2. We show furthermore that BMAL1 expression levels correlate inversely with MYC levels in 102 human lymphomas. Our data suggest that MYC acts as a master coordinator that inversely modulates the impact of cell cycle and circadian clock on gene expression. PMID:27339797

  15. MYC/MIZ1-dependent gene repression inversely coordinates the circadian clock with cell cycle and proliferation.

    PubMed

    Shostak, Anton; Ruppert, Bianca; Ha, Nati; Bruns, Philipp; Toprak, Umut H; Eils, Roland; Schlesner, Matthias; Diernfellner, Axel; Brunner, Michael

    2016-01-01

    The circadian clock and the cell cycle are major cellular systems that organize global physiology in temporal fashion. It seems conceivable that the potentially conflicting programs are coordinated. We show here that overexpression of MYC in U2OS cells attenuates the clock and conversely promotes cell proliferation while downregulation of MYC strengthens the clock and reduces proliferation. Inhibition of the circadian clock is crucially dependent on the formation of repressive complexes of MYC with MIZ1 and subsequent downregulation of the core clock genes BMAL1 (ARNTL), CLOCK and NPAS2. We show furthermore that BMAL1 expression levels correlate inversely with MYC levels in 102 human lymphomas. Our data suggest that MYC acts as a master coordinator that inversely modulates the impact of cell cycle and circadian clock on gene expression. PMID:27339797

  16. Deletion of clock gene Per2 exacerbates cholestatic liver injury and fibrosis in mice.

    PubMed

    Chen, Peng; Kakan, Xiamusiya; Wang, Shiming; Dong, Wei; Jia, Aiqun; Cai, Chun; Zhang, Jianfa

    2013-05-01

    The Period 2 (Per2) gene is an important component of the circadian system and is thought to modulate many physiological and pathological processes in mammals. In the previous study, we have disclosed the protective role of Per2 against carbon tetrachloride induced liver injury and fibrosis. Here we further assess the effect of Per2 deficiency on cholestatic hepatic injury and fibrosis. Cholestasis was induced by bile duct ligation (BDL) for 10 days in wild-type (WT) and Per2(-/-) mice. Masson trichrome staining and analysis of α-SMA immunohistochemistry were performed to show the collagen accumulation and the HSC activation, respectively. The mRNA levels of fibrosis-related genes were monitored by quantitative real-time PCR. Following BDL, livers from Per2(-/-) mice exhibited markedly increased extent of bile infarct and extracellular matrix (ECM) deposition compared with WT mice. Furthermore, the expressions of fibrosis-related genes like TNF-α, TGF-β1, Col1α1 and TIMP-1 were dramatically elevated in Per2(-/-) cholestatic liver. Our observations indicated that clock gene Per2 plays a protective role in mediating liver injury and fibrosis during cholestasis. PMID:22261359

  17. Identification and characterization of circadian clock genes in a native tobacco, Nicotiana attenuata

    PubMed Central

    2012-01-01

    Background A plant’s endogenous clock (circadian clock) entrains physiological processes to light/dark and temperature cycles. Forward and reverse genetic approaches in Arabidopsis have revealed the mechanisms of the circadian clock and its components in the genome. Similar approaches have been used to characterize conserved clock elements in several plant species. A wild tobacco, Nicotiana attenuata has been studied extensively to understand responses to biotic or abiotic stress in the glasshouse and also in their native habitat. During two decades of field experiment, we observed several diurnal rhythmic traits of N. attenuata in nature. To expand our knowledge of circadian clock function into the entrainment of traits important for ecological processes, we here report three core clock components in N. attenuata. Results Protein similarity and transcript accumulation allowed us to isolate orthologous genes of the core circadian clock components, LATE ELONGATED HYPOCOTYL (LHY), TIMING OF CAB EXPRESSION 1/PSEUDO-RESPONSE REGULATOR 1 (TOC1/PRR1), and ZEITLUPE (ZTL). Transcript accumulation of NaLHY peaked at dawn and NaTOC1 peaked at dusk in plants grown under long day conditions. Ectopic expression of NaLHY and NaZTL in Arabidopsis resulted in elongated hypocotyl and late-flowering phenotypes. Protein interactions between NaTOC1 and NaZTL were confirmed by yeast two-hybrid assays. Finally, when NaTOC1 was silenced in N. attenuata, late-flowering phenotypes under long day conditions were clearly observed. Conclusions We identified three core circadian clock genes in N. attenuata and demonstrated the functional and biochemical conservation of NaLHY, NaTOC1, and NaZTL. PMID:23006446

  18. Altered circadian rhythm of the clock genes in fibrotic livers induced by carbon tetrachloride.

    PubMed

    Chen, Peng; Kakan, Xiamusiya; Zhang, Jianfa

    2010-04-16

    Disruption in circadian rhythms either by mutation in mice or by shiftwork in people, is associated with an increased risk for the development of multiple organ diseases. In turn, organ disease may influence the function of clock genes and peripheral circadian systems. Here we showed that hepatic fibrosis induced by carbon tetrachloride in mice leads to alterations in the circadian rhythms of hepatic clock genes. Especially, we found an impaired daily Cry2 rhythm in the fibrotic livers, with markedly decreased levels during the day time while compared with control livers. Associatively, the expressions of two important clock-regulated genes peroxisome proliferator-activated receptor alpha and cytochrome P450 oxidoreductase lost circadian rhythm with significantly decreased levels during the light-dark (12/12h) cycle in fibrotic livers. PMID:20233594

  19. Demographic history and adaptation account for clock gene diversity in humans.

    PubMed

    Dall'Ara, I; Ghirotto, S; Ingusci, S; Bagarolo, G; Bertolucci, C; Barbujani, G

    2016-09-01

    Circadian clocks give rise to daily oscillations in behavior and physiological functions that often anticipate upcoming environmental changes generated by the Earth rotation. In model organisms a relationship exists between several genes affecting the circadian rhythms and latitude. We investigated the allele distributions at 116 000 single-nucleotide polymorphisms (SNPs) of 25 human clock and clock-related genes from the 1000Genomes Project, and at a reference data set of putatively neutral polymorphisms. The global genetic structure at the clock genes did not differ from that observed at the reference data set. We then tested for evidence of local adaptation searching for FST outliers under both an island and a hierarchical model, and for significant association between allele frequencies and environmental variables by a Bayesian approach. A total of 230 SNPs in 23 genes, or 84 SNPs in 19 genes, depending on the significance thresholds chosen, showed signs of local adaptation, whereas a maximum of 190 SNPs in 23 genes had significant covariance with one or more environmental variables. Only two SNPs from two genes (NPAS2 and AANAT) exhibit both elevated population differentiation and covariance with at least one environmental variable. We then checked whether the SNPs emerging from these analyses fall within a set of candidate SNPs associated with different chronotypes or sleep disorders. Correlation of five such SNPs with environmental variables supports a selective role of latitude or photoperiod, but certainly not a major one. PMID:27301334

  20. Association of CLOCK, ARNTL, and NPAS2 gene polymorphisms and seasonal variations in mood and behavior.

    PubMed

    Kim, Hae-In; Lee, Heon-Jeong; Cho, Chul-Hyun; Kang, Seung-Gul; Yoon, Ho-Kyoung; Park, Young-Min; Lee, Seung-Hwan; Moon, Joung-Ho; Song, Hye-Min; Lee, Eunil; Kim, Leen

    2015-01-01

    Seasonal affective disorder (SAD) is a condition of seasonal mood changes characterized by recurrent depression in autumn or winter that spontaneously remits in spring or summer. Evidence has suggested that circadian gene variants contribute to the pathogenesis of SAD. In this study, we investigated polymorphisms in the CLOCK, ARNTL, and NPAS2 genes in relation to seasonal variation in 507 healthy young adults. Seasonal variations were assessed with the Seasonality Pattern Assessment Questionnaire. The prevalence of SAD was 12.0% (winter-type 9.3%, summer-type 2.8%). No significant difference was found between the groups in the genotype distribution of ARNTL rs2278749 and NPAS2 rs2305160. The T allele of CLOCK rs1801260 was significantly more frequent in seasonals (SAD + subsyndromal SAD) compared with non-seasonals (p = 0.020, odds ratio = 1.89, 95% confidence interval = 1.09-3.27). Global seasonality score was significantly different among genotypes of CLOCK rs1801260, but not among genotypes of ARNTL rs2278749 and NPAS2 rs2305160. However, statistical difference was observed in the body weight and appetite subscales among genotypes of ARNTL rs2278749 and in the body weight subscale among genotypes of NPAS2 rs2305160. There was synergistic interaction between CLOCK rs1801260 and ARNTL rs2278749 on seasonality. To our knowledge, this study is the first to reveal an association between the CLOCK gene and seasonal variations in mood and behavior in the Korean population. Although we cannot confirm previous findings of an association between SAD and the ARNTL and NPAS2 genes, these genes may influence seasonal variations through metabolic factors such as body weight and appetite. The interaction of the CLOCK and ARNTL genes contributes to susceptibility for SAD. PMID:26134245

  1. Time-related dynamics of variation in core clock gene expression levels in tissues relevant to the immune system.

    PubMed

    Mazzoccoli, G; Sothern, R B; Greco, A; Pazienza, V; Vinciguerra, M; Liu, S; Cai, Y

    2011-01-01

    Immune parameters show rhythmic changes with a 24-h periodicity driven by an internal circadian timing system that relies on clock genes (CGs). CGs form interlocked transcription-translation feedback loops to generate and maintain 24-h mRNA and protein oscillations. In this study we evaluate and compare the profiles and the dynamics of variation of CG expression in peripheral blood, and two lymphoid tissues of mice. Expression levels of seven recognized key CGs (mBmal1, mClock, mPer1, mPer2, mCry1, mCry2, and Rev-erbalpha) were evaluated by quantitative RT- PCR in spleen, thymus and peripheral blood of C57BL/6 male mice housed on a 12-h light (L)-dark (D) cycle and sacrificed every 4 h for 24 h (3-4 mice/time point). We found a statistically significant time-effect in spleen (S), thymus (T) and blood (B) for the original values of expression level of mBmal1 (S), mClock (T, B), mPer1 (S, B), mPer2 (S), mCry1 (S), mCry2 (B) and mRev-Erbalpha (S, T, B) and for the fractional variation calculated between single time-point expression value of mBmal1 (B), mPer2 (T), mCry2 (B) and mRev-Erbalpha (S). A significant 24-h rhythm was validated for five CGs in blood (mClock, mPer1, mPer2, mCry2, mRev-Erbalpha), for four CGs in the spleen (mBmal1, mPer1, mPer2, mRev-Erbalpha), and for three CGs in the thymus (mClock, mPer2, mRev-Erbalpha). The original values of acrophases for mBmal1, mClock, mPer1, mPer2, mCry1 and mCry2 were very similar for spleen and thymus and advanced by several hours for peripheral blood compared to the lymphoid tissues, whereas the phases of mRev-Erbalpha were coincident for all three tissues. In conclusion, central and peripheral lymphoid tissues in the mouse show different sequences of activation of clock gene expression compared to peripheral blood. These differences may underlie the compartmental pattern of web functioning in the immune system. PMID:22230394

  2. Clock gene polymorphism and scheduling of migration: a geolocator study of the barn swallow Hirundo rustica.

    PubMed

    Bazzi, Gaia; Ambrosini, Roberto; Caprioli, Manuela; Costanzo, Alessandra; Liechti, Felix; Gatti, Emanuele; Gianfranceschi, Luca; Podofillini, Stefano; Romano, Andrea; Romano, Maria; Scandolara, Chiara; Saino, Nicola; Rubolini, Diego

    2015-01-01

    Circannual rhythms often rely on endogenous seasonal photoperiodic timers involving 'clock' genes, and Clock gene polymorphism has been associated to variation in phenology in some bird species. In the long-distance migratory barn swallow Hirundo rustica, individuals bearing the rare Clock allele with the largest number of C-terminal polyglutamine repeats found in this species (Q8) show a delayed reproduction and moult later. We explored the association between Clock polymorphism and migration scheduling, as gauged by light-level geolocators, in two barn swallow populations (Switzerland; Po Plain, Italy). Genetic polymorphism was low: 91% of the 64 individuals tracked year-round were Q7/Q7 homozygotes. We compared the phenology of the rare genotypes with the phenotypic distribution of Q7/Q7 homozygotes within each population. In Switzerland, compared to Q7/Q7, two Q6/Q7 males departed earlier from the wintering grounds and arrived earlier to their colony in spring, while a single Q7/Q8 female was delayed for both phenophases. On the other hand, in the Po Plain, three Q6/Q7 individuals had a similar phenology compared to Q7/Q7. The Swiss data are suggestive for a role of genetic polymorphism at a candidate phenological gene in shaping migration traits, and support the idea that Clock polymorphism underlies phenological variation in birds. PMID:26197782

  3. A new gene encoding a putative transcription factor regulated by the Drosophila circadian clock.

    PubMed

    Rouyer, F; Rachidi, M; Pikielny, C; Rosbash, M

    1997-07-01

    Circadian rhythms of locomotor activity and eclosion in Drosophila depend upon the reciprocal autoregulation of the period (per) and timeless (tim) genes. As part of this regulatory loop, per and tim mRNA levels oscillate in a circadian fashion. Other cycling transcripts may participate in this central pacemaker mechanism or represent outputs of the clock. In this paper, we report the isolation of Crg-1, a new circadianly regulated gene. Like per and tim transcript levels, Crg-1 transcript levels oscillate with a 24 h period in light:dark (LD) conditions, with a maximal abundance at the beginning of the night. These oscillations persist in complete darkness and depend upon per and tim proteins. The putative CRG-1 proteins show some sequence similarity with the DNA-binding domain of the HNF3/fork head family of transcription factors. In the adult head, in situ hybridization analysis reveals that per and Crg-1 have similar expression patterns in the eyes and optic lobes. PMID:9233804

  4. Diurnal Corticosterone Presence and Phase Modulate Clock Gene Expression in the Male Rat Prefrontal Cortex.

    PubMed

    Woodruff, Elizabeth R; Chun, Lauren E; Hinds, Laura R; Spencer, Robert L

    2016-04-01

    Mood disorders are associated with dysregulation of prefrontal cortex (PFC) function, circadian rhythms, and diurnal glucocorticoid (corticosterone [CORT]) circulation. Entrainment of clock gene expression in some peripheral tissues depends on CORT. In this study, we characterized over the course of the day the mRNA expression pattern of the core clock genes Per1, Per2, and Bmal1 in the male rat PFC and suprachiasmatic nucleus (SCN) under different diurnal CORT conditions. In experiment 1, rats were left adrenal-intact (sham) or were adrenalectomized (ADX) followed by 10 daily antiphasic (opposite time of day of the endogenous CORT peak) ip injections of either vehicle or 2.5 mg/kg CORT. In experiment 2, all rats received ADX surgery followed by 13 daily injections of vehicle or CORT either antiphasic or in-phase with the endogenous CORT peak. In sham rats clock gene mRNA levels displayed a diurnal pattern of expression in the PFC and the SCN, but the phase differed between the 2 structures. ADX substantially altered clock gene expression patterns in the PFC. This alteration was normalized by in-phase CORT treatment, whereas antiphasic CORT treatment appears to have eliminated a diurnal pattern (Per1 and Bmal1) or dampened/inverted its phase (Per2). There was very little effect of CORT condition on clock gene expression in the SCN. These experiments suggest that an important component of glucocorticoid circadian physiology entails CORT regulation of the molecular clock in the PFC. Consequently, they also point to a possible mechanism that contributes to PFC disrupted function in disorders associated with abnormal CORT circulation. PMID:26901093

  5. Neural clocks and Neuropeptide F/Y regulate circadian gene expression in a peripheral metabolic tissue.

    PubMed

    Erion, Renske; King, Anna N; Wu, Gang; Hogenesch, John B; Sehgal, Amita

    2016-01-01

    Metabolic homeostasis requires coordination between circadian clocks in different tissues. Also, systemic signals appear to be required for some transcriptional rhythms in the mammalian liver and the Drosophila fat body. Here we show that free-running oscillations of the fat body clock require clock function in the PDF-positive cells of the fly brain. Interestingly, rhythmic expression of the cytochrome P450 transcripts, sex-specific enzyme 1 (sxe1) and Cyp6a21, which cycle in the fat body independently of the local clock, depends upon clocks in neurons expressing neuropeptide F (NPF). NPF signaling itself is required to drive cycling of sxe1 and Cyp6a21 in the fat body, and its mammalian ortholog, Npy, functions similarly to regulate cycling of cytochrome P450 genes in the mouse liver. These data highlight the importance of neuronal clocks for peripheral rhythms, particularly in a specific detoxification pathway, and identify a novel and conserved role for NPF/Npy in circadian rhythms. PMID:27077948

  6. Neural clocks and Neuropeptide F/Y regulate circadian gene expression in a peripheral metabolic tissue

    PubMed Central

    Erion, Renske; King, Anna N; Wu, Gang; Hogenesch, John B; Sehgal, Amita

    2016-01-01

    Metabolic homeostasis requires coordination between circadian clocks in different tissues. Also, systemic signals appear to be required for some transcriptional rhythms in the mammalian liver and the Drosophila fat body. Here we show that free-running oscillations of the fat body clock require clock function in the PDF-positive cells of the fly brain. Interestingly, rhythmic expression of the cytochrome P450 transcripts, sex-specific enzyme 1 (sxe1) and Cyp6a21, which cycle in the fat body independently of the local clock, depends upon clocks in neurons expressing neuropeptide F (NPF). NPF signaling itself is required to drive cycling of sxe1 and Cyp6a21 in the fat body, and its mammalian ortholog, Npy, functions similarly to regulate cycling of cytochrome P450 genes in the mouse liver. These data highlight the importance of neuronal clocks for peripheral rhythms, particularly in a specific detoxification pathway, and identify a novel and conserved role for NPF/Npy in circadian rhythms. DOI: http://dx.doi.org/10.7554/eLife.13552.001 PMID:27077948

  7. Search for evidence of a clock related to the solar 154 day complex of periodicities

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.; Bai, T.

    1992-01-01

    Evidence that has recently been compiled (Bai and Sturrock 1991) indicates that the enigmatic 154-day periodicity in solar activity may be viewed as part of a complex of periodicities that are approximate multiples of 25.8 days, suggesting that the Sun contains a 'clock' with frequency in the range 440 to 463 nano Hz. The clock may comprise either an oscillator or a rotator, each of which may be either real or virtual. We have reconsidered a previous spectrum analysis of the Zurich sunspot-number sequence by Knight, Schatten, and Sturrock (1979) which revealed a sharp, persistent and significant periodicity with a period of 12.072 days, corresponding to a frequency of about 958.8 nano Hz. This periodicity may be regarded as the (second) upper sideband of the second harmonic (2nu(sub R) + 2nu(sub E)) of a fundamental frequency of 447.7 nano Hz that is clearly within the search band. In this expression, nu(sub R) is the sidereal frequency of the hypothetical rotator and nu(sub E) is the frequency (31.69 nano Hz) of the Earth in its orbital motion around the Sun. In analyzing sunspot area data derived from the Greenwich data set, and on noting that any frequency is defined only to within the Nyquist frequency, we find clear evidence not only for the upper sideband of the second harmonic, but also for the second harmonic (2nu(sub R)) and the lower sideband of the second harmonic (2nu(sub R) - 2nu(sub E)). There is no strong peak at the fundamental frequency in the Greenwich data, but there is in the Zurich sunspot data. The effect of a linear oscillator is, to the lowest order in the amplitude, the same as the combined effect of two rotators of opposite polarities. A rotator that has arbitrary orientation with respect to the ecliptic may influence the outer layers of the Sun and thereby modulate the occurrence of solar activity such as sunspots. By analyzing a simple model, we find that such a rotator would influence surface activity in such a way that the spectrum of

  8. The Zebrafish Period2 Protein Positively Regulates the Circadian Clock through Mediation of Retinoic Acid Receptor (RAR)-related Orphan Receptor α (Rorα)*

    PubMed Central

    Wang, Mingyong; Zhong, Zhaomin; Zhong, Yingbin; Zhang, Wei; Wang, Han

    2015-01-01

    We report the characterization of a null mutant for zebrafish circadian clock gene period2 (per2) generated by transcription activator-like effector nuclease and a positive role of PER2 in vertebrate circadian regulation. Locomotor experiments showed that per2 mutant zebrafish display reduced activities under light-dark and 2-h phase delay under constant darkness, and quantitative real time PCR analyses showed up-regulation of cry1aa, cry1ba, cry1bb, and aanat2 but down-regulation of per1b, per3, and bmal1b in per2 mutant zebrafish, suggesting that Per2 is essential for the zebrafish circadian clock. Luciferase reporter assays demonstrated that Per2 represses aanat2 expression through E-box and enhances bmal1b expression through the Ror/Rev-erb response element, implicating that Per2 plays dual roles in the zebrafish circadian clock. Cell transfection and co-immunoprecipitation assays revealed that Per2 enhances bmal1b expression through binding to orphan nuclear receptor Rorα. The enhancing effect of mouse PER2 on Bmal1 transcription is also mediated by RORα even though it binds to REV-ERBα. Moreover, zebrafish Per2 also appears to have tissue-specific regulatory roles in numerous peripheral organs. These findings help define the essential functions of Per2 in the zebrafish circadian clock and in particular provide strong evidence for a positive role of PER2 in the vertebrate circadian system. PMID:25544291

  9. A Circadian Clock Gene, Cry, Affects Heart Morphogenesis and Function in Drosophila as Revealed by Optical Coherence Microscopy.

    PubMed

    Alex, Aneesh; Li, Airong; Zeng, Xianxu; Tate, Rebecca E; McKee, Mary L; Capen, Diane E; Zhang, Zhan; Tanzi, Rudolph E; Zhou, Chao

    2015-01-01

    Circadian rhythms are endogenous, entrainable oscillations of physical, mental and behavioural processes in response to local environmental cues such as daylight, which are present in the living beings, including humans. Circadian rhythms have been related to cardiovascular function and pathology. However, the role that circadian clock genes play in heart development and function in a whole animal in vivo are poorly understood. The Drosophila cryptochrome (dCry) is a circadian clock gene that encodes a major component of the circadian clock negative feedback loop. Compared to the embryonic stage, the relative expression levels of dCry showed a significant increase (>100-fold) in Drosophila during the pupa and adult stages. In this study, we utilized an ultrahigh resolution optical coherence microscopy (OCM) system to perform non-invasive and longitudinal analysis of functional and morphological changes in the Drosophila heart throughout its post-embryonic lifecycle for the first time. The Drosophila heart exhibited major morphological and functional alterations during its development. Notably, heart rate (HR) and cardiac activity period (CAP) of Drosophila showed significant variations during the pupa stage, when heart remodeling took place. From the M-mode (2D + time) OCM images, cardiac structural and functional parameters of Drosophila at different developmental stages were quantitatively determined. In order to study the functional role of dCry on Drosophila heart development, we silenced dCry by RNAi in the Drosophila heart and mesoderm, and quantitatively measured heart morphology and function in those flies throughout its development. Silencing of dCry resulted in slower HR, reduced CAP, smaller heart chamber size, pupal lethality and disrupted posterior segmentation that was related to increased expression of a posterior compartment protein, wingless. Collectively, our studies provided novel evidence that the circadian clock gene, dCry, plays an essential

  10. A Circadian Clock Gene, Cry, Affects Heart Morphogenesis and Function in Drosophila as Revealed by Optical Coherence Microscopy

    PubMed Central

    Zeng, Xianxu; Tate, Rebecca E.; McKee, Mary L.; Capen, Diane E.; Zhang, Zhan; Tanzi, Rudolph E.; Zhou, Chao

    2015-01-01

    Circadian rhythms are endogenous, entrainable oscillations of physical, mental and behavioural processes in response to local environmental cues such as daylight, which are present in the living beings, including humans. Circadian rhythms have been related to cardiovascular function and pathology. However, the role that circadian clock genes play in heart development and function in a whole animal in vivo are poorly understood. The Drosophila cryptochrome (dCry) is a circadian clock gene that encodes a major component of the circadian clock negative feedback loop. Compared to the embryonic stage, the relative expression levels of dCry showed a significant increase (>100-fold) in Drosophila during the pupa and adult stages. In this study, we utilized an ultrahigh resolution optical coherence microscopy (OCM) system to perform non-invasive and longitudinal analysis of functional and morphological changes in the Drosophila heart throughout its post-embryonic lifecycle for the first time. The Drosophila heart exhibited major morphological and functional alterations during its development. Notably, heart rate (HR) and cardiac activity period (CAP) of Drosophila showed significant variations during the pupa stage, when heart remodeling took place. From the M-mode (2D + time) OCM images, cardiac structural and functional parameters of Drosophila at different developmental stages were quantitatively determined. In order to study the functional role of dCry on Drosophila heart development, we silenced dCry by RNAi in the Drosophila heart and mesoderm, and quantitatively measured heart morphology and function in those flies throughout its development. Silencing of dCry resulted in slower HR, reduced CAP, smaller heart chamber size, pupal lethality and disrupted posterior segmentation that was related to increased expression of a posterior compartment protein, wingless. Collectively, our studies provided novel evidence that the circadian clock gene, dCry, plays an essential

  11. Genetic dissection of psychopathological symptoms: insomnia in mood disorders and CLOCK gene polymorphism.

    PubMed

    Serretti, Alessandro; Benedetti, Francesco; Mandelli, Laura; Lorenzi, Cristina; Pirovano, Adele; Colombo, Cristina; Smeraldi, Enrico

    2003-08-15

    We investigated the possible effect of the 3111T/C CLOCK gene polymorphism on sleep disorders in a sample of 620 patients affected by major depressive disorder (MDD) and bipolar disorder (BP). We detected a significantly higher recurrence of initial (P = 0.0001), middle (P = 0.0009), and early (P = 0.0008) insomnia in homozygotes for the C variant and a similar trend concerning decreased need of sleep in BP (P = 0.0074). Other demographic and clinical features were found not related with CLOCK polymorphisms. This preliminary observation leads to hypothesize a possible involvement of the CLOCK gene polymorphism in the sleep disregulations in MDD and BP. PMID:12898572

  12. Molecular Mechanisms that Regulate the Coupled Period of the Mammalian Circadian Clock

    NASA Astrophysics Data System (ADS)

    Kim, Jae Kyoung; Kilpatrick, Zachary P.; Bennett, Matthew R.; Josić, Krešimir

    2014-05-01

    In mammals, most cells in the brain and peripheral tissues generate circadian (~24hr) rhythms autonomously. These self-sustained rhythms are coordinated and entrained by a master circadian clock in the suprachiasmatic nucleus (SCN). Within the SCN, the individual rhythms of each neuron are synchronized through intercellular signaling. One important feature of SCN is that the synchronized period is close to the cell population mean of intrinsic periods. In this way, the synchronized period of the SCN stays close to the periods of cells in peripheral tissues. This is important for SCN to entrain cells throughout the body. However, the mechanism that drives the period of the coupled SCN cells to the population mean is not known. We use mathematical modeling and analysis to show that the mechanism of transcription repression plays a pivotal role in regulating the coupled period. Specifically, we use phase response curve analysis to show that the coupled period within the SCN stays near the population mean if transcriptional repression occurs via protein sequestration. In contrast, the coupled period is far from the mean if repression occurs through highly nonlinear Hill-type regulation (e.g. oligomer- or phosphorylation-based repression). Furthermore, we find that the timescale of intercellular coupling needs to be fast compared to that of intracellular feedback to maintain the mean period. These findings reveal the important relationship between the intracellular transcriptional feedback loop and intercellular coupling. This relationship explains why transcriptional repression appears to occur via protein sequestration in multicellular organisms, mammals and Drosophila, in contrast with the phosphorylation-based repression in unicellular organisms. That is, transition to protein sequestration is essential for synchronizing multiple cells with a period close to the population mean (~24hr).

  13. Oscillating gene expression determines competence for periodic Arabidopsis root branching.

    PubMed

    Moreno-Risueno, Miguel A; Van Norman, Jaimie M; Moreno, Antonio; Zhang, Jingyuan; Ahnert, Sebastian E; Benfey, Philip N

    2010-09-10

    Plants and animals produce modular developmental units in a periodic fashion. In plants, lateral roots form as repeating units along the root primary axis; however, the developmental mechanism regulating this process is unknown. We found that cyclic expression pulses of a reporter gene mark the position of future lateral roots by establishing prebranch sites and that prebranch site production and root bending are periodic. Microarray and promoter-luciferase studies revealed two sets of genes oscillating in opposite phases at the root tip. Genetic studies show that some oscillating transcriptional regulators are required for periodicity in one or both developmental processes. This molecular mechanism has characteristics that resemble molecular clock-driven activities in animal species. PMID:20829477

  14. Extent of mismatch between the period of circadian clocks and light/dark cycles determines time-to-emergence in fruit flies.

    PubMed

    Yadav, Pankaj; Choudhury, Deepak; Sadanandappa, Madhumala K; Sharma, Vijay Kumar

    2015-08-01

    Circadian clocks time developmental stages of fruit flies Drosophila melanogaster, while light/dark (LD) cycles delimit emergence of adults, conceding only during the "allowed gate." Previous studies have revealed that time-to-emergence can be altered by mutations in the core clock gene period (per), or by altering the length of LD cycles. Since this evidence came from studies on genetically manipulated flies, or on flies maintained under LD cycles with limited range of periods, inferences that can be drawn are limited. Moreover, the extent of shortening or lengthening of time-to-emergence remains yet unknown. In order to pursue this further, we assayed time-to-emergence of D. melanogaster under 12 different LD cycles as well as in constant light (LL) and constant dark conditions (DD). Time-to-emergence in flies occurred earlier under LL than in LD cycles and DD. Among the LD cycles, time-to-emergence occurred earlier under T4-T8, followed by T36-T48, and then T12-T32, suggesting that egg-to-emergence duration in flies becomes shorter when the length of LD cycles deviates from 24 h, bearing a strong positive and a marginally negative correlation with day length, for values shorter and longer than 24 h, respectively. These results suggest that the extent of mismatch between the period of circadian clocks and environmental cycles determines the time-to-emergence in Drosophila. PMID:24668961

  15. Nucleotide sequences of immunoglobulin eta genes of chimpanzee and orangutan: DNA molecular clock and hominoid evolution

    SciTech Connect

    Sakoyama, Y.; Hong, K.J.; Byun, S.M.; Hisajima, H.; Ueda, S.; Yaoita, Y.; Hayashida, H.; Miyata, T.; Honjo, T.

    1987-02-01

    To determine the phylogenetic relationships among hominoids and the dates of their divergence, the complete nucleotide sequences of the constant region of the immunoglobulin eta-chain (C/sub eta1/) genes from chimpanzee and orangutan have been determined. These sequences were compared with the human eta-chain constant-region sequence. A molecular clock (silent molecular clock), measured by the degree of sequence divergence at the synonymous (silent) positions of protein-encoding regions, was introduced for the present study. From the comparison of nucleotide sequences of ..cap alpha../sub 1/-antitrypsin and ..beta..- and delta-globulin genes between humans and Old World monkeys, the silent molecular clock was calibrated: the mean evolutionary rate of silent substitution was determined to be 1.56 x 10/sup -9/ substitutions per site per year. Using the silent molecular clock, the mean divergence dates of chimpanzee and orangutan from the human lineage were estimated as 6.4 +/- 2.6 million years and 17.3 +/- 4.5 million years, respectively. It was also shown that the evolutionary rate of primate genes is considerably slower than those of other mammalian genes.

  16. The role of feeding rhythm, adrenal hormones and neuronal inputs in synchronizing daily clock gene rhythms in the liver.

    PubMed

    Su, Yan; Cailotto, Cathy; Foppen, Ewout; Jansen, Remi; Zhang, Zhi; Buijs, Ruud; Fliers, Eric; Kalsbeek, Andries

    2016-02-15

    The master clock in the hypothalamic suprachiasmatic nucleus (SCN) is assumed to distribute rhythmic information to the periphery via neural, humoral and/or behavioral connections. Until now, feeding, corticosterone and neural inputs are considered important signals for synchronizing daily rhythms in the liver. In this study, we investigated the necessity of neural inputs as well as of the feeding and adrenal hormone rhythms for maintaining daily hepatic clock gene rhythms. Clock genes kept their daily rhythm when only one of these three signals was disrupted, or when we disrupted hepatic neuronal inputs together with the adrenal hormone rhythm or with the daily feeding rhythm. However, all clock genes studied lost their daily expression rhythm after simultaneous disruption of the feeding and adrenal hormone rhythm. These data indicate that either a daily rhythm of feeding or adrenal hormones should be present to synchronize clock gene rhythms in the liver with the SCN. PMID:26704081

  17. Clock gene polymorphism and scheduling of migration: a geolocator study of the barn swallow Hirundo rustica

    PubMed Central

    Bazzi, Gaia; Ambrosini, Roberto; Caprioli, Manuela; Costanzo, Alessandra; Liechti, Felix; Gatti, Emanuele; Gianfranceschi, Luca; Podofillini, Stefano; Romano, Andrea; Romano, Maria; Scandolara, Chiara; Saino, Nicola; Rubolini, Diego

    2015-01-01

    Circannual rhythms often rely on endogenous seasonal photoperiodic timers involving ‘clock’ genes, and Clock gene polymorphism has been associated to variation in phenology in some bird species. In the long-distance migratory barn swallow Hirundo rustica, individuals bearing the rare Clock allele with the largest number of C-terminal polyglutamine repeats found in this species (Q8) show a delayed reproduction and moult later. We explored the association between Clock polymorphism and migration scheduling, as gauged by light-level geolocators, in two barn swallow populations (Switzerland; Po Plain, Italy). Genetic polymorphism was low: 91% of the 64 individuals tracked year-round were Q7/Q7 homozygotes. We compared the phenology of the rare genotypes with the phenotypic distribution of Q7/Q7 homozygotes within each population. In Switzerland, compared to Q7/Q7, two Q6/Q7 males departed earlier from the wintering grounds and arrived earlier to their colony in spring, while a single Q7/Q8 female was delayed for both phenophases. On the other hand, in the Po Plain, three Q6/Q7 individuals had a similar phenology compared to Q7/Q7. The Swiss data are suggestive for a role of genetic polymorphism at a candidate phenological gene in shaping migration traits, and support the idea that Clock polymorphism underlies phenological variation in birds. PMID:26197782

  18. The orphan receptor Rev-erbα gene is a target of the circadian clock pacemaker

    PubMed Central

    Triqueneaux, Gérard; Thenot, Sandrine; Kakizawa, Tomoko; Antoch, Marina P; Safi, Rachid; Takahashi, Joseph S; Delaunay, Franck; Laudet, Vincent

    2013-01-01

    Rev-erbα is a ubiquitously expressed orphan nuclear receptor which functions as a constitutive transcriptional repressor and is expressed in vertebrates according to a robust circadian rhythm. We report here that two Rev-erbα mRNA isoforms, namely Rev-erbα1 and Rev-erbα2, are generated through alternative promoter usage and that both show a circadian expression pattern in an in vitro system using serum-shocked fibroblasts. Both promoter regions P1 (Rev-erbα1) and P2 (Rev-erbα2) contain several E-box DNA sequences, which function as response elements for the core circadian-clock components: CLOCK and BMAL1. The CLOCK–BMAL1 heterodimer stimulates the activity of both P1 and P2 promoters in transient transfection assay by 3–6-fold. This activation was inhibited by the overexpression of CRY1, a component of the negative limb of the circadian transcriptional loop. Critical E-box elements were mapped within both promoters. This regulation is conserved in vertebrates since we found that the CLOCK–BMAL1 heterodimer also regulates the zebrafish Rev-erbα gene. In line with these data Rev-erbα circadian expression was strongly impaired in the livers of Clock mutant mice and in the pineal glands of zebrafish embryos treated with Clock and Bmal1 antisense oligonucleotides. Together these data demonstrate that CLOCK is a critical regulator of Rev-erbα circadian gene expression in evolutionarily distant vertebrates and suggest a role for Rev-erbα in the circadian clock output. PMID:15591021

  19. The rhythmic expression of clock genes attenuated in human plaque-derived vascular smooth muscle cells

    PubMed Central

    2014-01-01

    Background Acute myocardial infarction and stroke are more likely to occur in the early morning. Circadian pacemakers are considered to be involved in the process. Many peripheral tissues and cells also contain clock systems. In this study, we examined whether the primary cultured human plaque-derived vascular smooth muscle cells (VSMCs) process circadian rhythmicity; furthermore, we investigated the expression difference of clock genes between normal human carotid VSMCs and human plaque-derived VSMCs. Methods Fifty-six human carotid plaques provided the atherosclerotic tissue, and 21 samples yielded viable cultured primary VSMCs. The normal carotid VSMCs were cultured from donors’ normal carotids. The mRNA levels of the target genes were measured by Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). Results After serum shock, both types of cells showed clear circadian expressions of Bmal1, Cry1, Cry2, Per1, Per2, Per3 and Rev-erbα mRNA; meanwhile the Clock mRNA show a rhythmic expression in plaque-derived SMCs but not in normal carotid VSMCs. The expression levels of these main clock genes were significantly attenuated in human plaque-derived VSMCs compared with normal human carotid VSMCs. The rhythm of Bmal1 mRNA in plaque-derived VSMCs was changed. Conclusion The present results demonstrate that the human plaque-derived VSMCs possess different circadian rhythmicity from that of normal carotid VSMCs. The rhythm changes of clock genes in plaque-derived VSMCs may be involved in the process of atherosclerosis and finally promote the rupture of plaque. PMID:24418196

  20. Stochastic Regulation of her1/7 Gene Expression Is the Source of Noise in the Zebrafish Somite Clock Counteracted by Notch Signalling

    PubMed Central

    Jenkins, Robert P.; Hanisch, Anja; Soza-Ried, Cristian; Sahai, Erik

    2015-01-01

    The somite segmentation clock is a robust oscillator used to generate regularly-sized segments during early vertebrate embryogenesis. It has been proposed that the clocks of neighbouring cells are synchronised via inter-cellular Notch signalling, in order to overcome the effects of noisy gene expression. When Notch-dependent communication between cells fails, the clocks of individual cells operate erratically and lose synchrony over a period of about 5 to 8 segmentation clock cycles (2–3 hours in the zebrafish). Here, we quantitatively investigate the effects of stochasticity on cell synchrony, using mathematical modelling, to investigate the likely source of such noise. We find that variations in the transcription, translation and degradation rate of key Notch signalling regulators do not explain the in vivo kinetics of desynchronisation. Rather, the analysis predicts that clock desynchronisation, in the absence of Notch signalling, is due to the stochastic dissociation of Her1/7 repressor proteins from the oscillating her1/7 autorepressed target genes. Using in situ hybridisation to visualise sites of active her1 transcription, we measure an average delay of approximately three minutes between the times of activation of the two her1 alleles in a cell. Our model shows that such a delay is sufficient to explain the in vivo rate of clock desynchronisation in Notch pathway mutant embryos and also that Notch-mediated synchronisation is sufficient to overcome this stochastic variation. This suggests that the stochastic nature of repressor/DNA dissociation is the major source of noise in the segmentation clock. PMID:26588097

  1. Circadian Clock Genes Are Essential for Normal Adult Neurogenesis, Differentiation, and Fate Determination.

    PubMed

    Malik, Astha; Kondratov, Roman V; Jamasbi, Roudabeh J; Geusz, Michael E

    2015-01-01

    Adult neurogenesis creates new neurons and glia from stem cells in the human brain throughout life. It is best understood in the dentate gyrus (DG) of the hippocampus and the subventricular zone (SVZ). Circadian rhythms have been identified in the hippocampus, but the role of any endogenous circadian oscillator cells in hippocampal neurogenesis and their importance in learning or memory remains unclear. Any study of stem cell regulation by intrinsic circadian timing within the DG is complicated by modulation from circadian clocks elsewhere in the brain. To examine circadian oscillators in greater isolation, neurosphere cultures were prepared from the DG of two knockout mouse lines that lack a functional circadian clock and from mPer1::luc mice to identify circadian oscillations in gene expression. Circadian mPer1 gene activity rhythms were recorded in neurospheres maintained in a culture medium that induces neurogenesis but not in one that maintains the stem cell state. Although the differentiating neural stem progenitor cells of spheres were rhythmic, evidence of any mature neurons was extremely sparse. The circadian timing signal originated in undifferentiated cells within the neurosphere. This conclusion was supported by immunocytochemistry for mPER1 protein that was localized to the inner, more stem cell-like neurosphere core. To test for effects of the circadian clock on neurogenesis, media conditions were altered to induce neurospheres from BMAL1 knockout mice to differentiate. These cultures displayed unusually high differentiation into glia rather than neurons according to GFAP and NeuN expression, respectively, and very few BetaIII tubulin-positive, immature neurons were observed. The knockout neurospheres also displayed areas visibly devoid of cells and had overall higher cell death. Neurospheres from arrhythmic mice lacking two other core clock genes, Cry1 and Cry2, showed significantly reduced growth and increased astrocyte proliferation during

  2. Circadian Clock Genes Are Essential for Normal Adult Neurogenesis, Differentiation, and Fate Determination

    PubMed Central

    Kondratov, Roman V.; Jamasbi, Roudabeh J.

    2015-01-01

    Adult neurogenesis creates new neurons and glia from stem cells in the human brain throughout life. It is best understood in the dentate gyrus (DG) of the hippocampus and the subventricular zone (SVZ). Circadian rhythms have been identified in the hippocampus, but the role of any endogenous circadian oscillator cells in hippocampal neurogenesis and their importance in learning or memory remains unclear. Any study of stem cell regulation by intrinsic circadian timing within the DG is complicated by modulation from circadian clocks elsewhere in the brain. To examine circadian oscillators in greater isolation, neurosphere cultures were prepared from the DG of two knockout mouse lines that lack a functional circadian clock and from mPer1::luc mice to identify circadian oscillations in gene expression. Circadian mPer1 gene activity rhythms were recorded in neurospheres maintained in a culture medium that induces neurogenesis but not in one that maintains the stem cell state. Although the differentiating neural stem progenitor cells of spheres were rhythmic, evidence of any mature neurons was extremely sparse. The circadian timing signal originated in undifferentiated cells within the neurosphere. This conclusion was supported by immunocytochemistry for mPER1 protein that was localized to the inner, more stem cell-like neurosphere core. To test for effects of the circadian clock on neurogenesis, media conditions were altered to induce neurospheres from BMAL1 knockout mice to differentiate. These cultures displayed unusually high differentiation into glia rather than neurons according to GFAP and NeuN expression, respectively, and very few BetaIII tubulin-positive, immature neurons were observed. The knockout neurospheres also displayed areas visibly devoid of cells and had overall higher cell death. Neurospheres from arrhythmic mice lacking two other core clock genes, Cry1 and Cry2, showed significantly reduced growth and increased astrocyte proliferation during

  3. Sleep disturbances and circadian CLOCK genes in borderline personality disorder.

    PubMed

    Fleischer, Monika; Schäfer, Michael; Coogan, Andrew; Häßler, Frank; Thome, Johannes

    2012-10-01

    Borderline personality disorder (BPD) is characterised by a deep-reaching pattern of affective instability, incoherent identity, self-injury, suicide attempts, and disturbed interpersonal relations and lifestyle. The daily activities of BPD patients are often chaotic and disorganized, with patients often staying up late while sleeping during the day. These behavioural patterns suggest that altered circadian rhythms may be associated with BPD. Furthermore, BPD patients frequently report suffering from sleep disturbances. In this review, we overview the evidence that circadian rhythms and sleep are disturbed in BPD, and we explore the possibility that personality traits that are pertinent for BPD may be associated with circadian typology, and perhaps to circadian genotypes. With regards to sleep architecture, we review the evidence that BPD patients display altered non-REM and REM sleep. A possible cue to a deeper understanding of this temporal dysregulation might be an analysis of the circadian clock at the molecular and cellular level, as well as behavioural studies using actigraphy and we suggest avenues for further exploration of these factors. PMID:22806005

  4. The Light Wavelength Affects the Ontogeny of Clock Gene Expression and Activity Rhythms in Zebrafish Larvae

    PubMed Central

    Di Rosa, Viviana; Frigato, Elena; López-Olmeda, José F.; Sánchez-Vázquez, Francisco J.; Bertolucci, Cristiano

    2015-01-01

    Light plays a key role in synchronizing rhythms and setting the phase of early development. However, to date, little is known about the impact of light wavelengths during the ontogeny of the molecular clock and the behavioural rhythmicity. The aim of this research was to determine the effect of light of different wavelengths (white, blue and red) on the onset of locomotor activity and clock gene (per1b, per2, clock1, bmal1 and dbp) expression rhythms. For this purpose, 4 groups of zebrafish embryo/larvae were raised from 0 to 7 days post-fertilization (dpf) under the following lighting conditions: three groups maintained under light:dark (LD) cycles with white (full visible spectrum, LDW), blue (LDB), or red light (LDR), and one group raised under constant darkness (DD). The results showed that lighting conditions influenced activity rhythms. Larvae were arrhythmic under DD, while under LD cycles they developed wavelength-dependent daily activity rhythms which appeared earlier under LDB (4 dpf) than under LDW or LDR (5 dpf). The results also revealed that development and lighting conditions influenced clock gene expression. While clock1 rhythmic expression appeared in all lighting conditions at 7 dpf, per1b, per2 and dbp showed daily variations already at 3 dpf. Curiously, bmal1 showed consistent rhythmic expression from embryonic stage (0 dpf). Summarizing, the data revealed that daily rhythms appeared earlier in the larvae reared under LDB than in those reared under LDW and LDR. These results emphasize the importance of lighting conditions and wavelengths during early development for the ontogeny of daily rhythms of gene expression and how these rhythms are reflected on the behavioural rhythmicity of zebrafish larvae. PMID:26147202

  5. Impact of clock gene Bmal1 deficiency on nutritionally induced obesity in mice.

    PubMed

    Hemmeryckx, Bianca; Himmelreich, Uwe; Hoylaerts, Marc F; Lijnen, Henri R

    2011-03-01

    To evaluate the hypothesis that the clock gene Bmal1 (brain and muscle arnt like protein-1) plays a role in the development of obesity, 5-week-old male Bmal1-deficient (Bmal1(-/-)) mice and wild-type littermates (Bmal1(+/+)) were kept on a high-fat diet (HFD) for 15 weeks. Despite an initial accelerated weight gain of Bmal1(-/-) mice, body weight and subcutaneous (SC) and gonadal (GON) adipose tissue mass were comparable to Bmal1(+/+) mice at the end of the diet period. Noninvasive magnetic resonance imaging scanning revealed a modest increase in fat content in Bmal1(-/-) mice after 10 weeks of HFD, whereas at the start and the end of the HFD feeding no differences were observed between both genotypes. After 15 weeks of HFD, adipocyte and blood vessel size and density were similar for Bmal1(+/+) and Bmal1(-/-) mice. However, the weight of major organs was significantly reduced in Bmal1(-/-) mice, confirming the premature ageing phenotype. Thus, we hypothesize that an initial accelerated increase in body weight and fat mass of Bmal1(-/-) mice on HFD may have been offset by the effect of premature ageing on organ weight, resulting in comparable weights after 15 weeks of HFD. PMID:21030946

  6. Clock-genes and mitochondrial respiratory activity: Evidence of a reciprocal interplay.

    PubMed

    Scrima, Rosella; Cela, Olga; Merla, Giuseppe; Augello, Bartolomeo; Rubino, Rosa; Quarato, Giovanni; Fugetto, Sabino; Menga, Marta; Fuhr, Luise; Relógio, Angela; Piccoli, Claudia; Mazzoccoli, Gianluigi; Capitanio, Nazzareno

    2016-08-01

    In the past few years mounting evidences have highlighted the tight correlation between circadian rhythms and metabolism. Although at the organismal level the central timekeeper is constituted by the hypothalamic suprachiasmatic nuclei practically all the peripheral tissues are equipped with autonomous oscillators made up by common molecular clockworks represented by circuits of gene expression that are organized in interconnected positive and negative feed-back loops. In this study we exploited a well-established in vitro synchronization model to investigate specifically the linkage between clock gene expression and the mitochondrial oxidative phosphorylation (OxPhos). Here we show that synchronized cells exhibit an autonomous ultradian mitochondrial respiratory activity which is abrogated by silencing the master clock gene ARNTL/BMAL1. Surprisingly, pharmacological inhibition of the mitochondrial OxPhos system resulted in dramatic deregulation of the rhythmic clock-gene expression and a similar result was attained with mtDNA depleted cells (Rho0). Our findings provide a novel level of complexity in the interlocked feedback loop controlling the interplay between cellular bioenergetics and the molecular clockwork. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi. PMID:27060253

  7. Glutamine synthetase gene evolution: a good molecular clock.

    PubMed Central

    Pesole, G; Bozzetti, M P; Lanave, C; Preparata, G; Saccone, C

    1991-01-01

    Glutamine synthetase (EC 6.3.1.2) gene evolution in various animals, plants, and bacteria was evaluated by a general stationary Markov model. The evolutionary process proved to be unexpectedly regular even for a time span as long as that between the divergence of prokaryotes from eukaryotes. This enabled us to draw phylogenetic trees for species whose phylogeny cannot be easily reconstructed from the fossil record. Our calculation of the times of divergence of the various organelle-specific enzymes led us to hypothesize that the pea and bean chloroplast genes for these enzymes originated from the duplication of nuclear genes as a result of the different metabolic needs of the various species. Our data indicate that the duplication of plastid glutamine synthetase genes occurred long after the endosymbiotic events that produced the organelles themselves. PMID:1671172

  8. Clock and clock-controlled genes are differently expressed in the retina, lamina and in selected cells of the visual system of Drosophila melanogaster.

    PubMed

    Damulewicz, Milena; Loboda, Agnieszka; Bukowska-Strakova, Karolina; Jozkowicz, Alicja; Dulak, Jozef; Pyza, Elzbieta

    2015-01-01

    The retina and the first optic neuropil (lamina) of Drosophila show circadian rhythms in various processes. To learn about the regulation of circadian rhythms in the retina and lamina and in two cell types, glial and the lamina L2 interneurons, we examined expression of the following clock genes; per, tim, clk, and cry and clock-controlled genes (ccgs); Atpα, nrv2, brp, Pdfr. We found that the expression of gene studied is specific for the retina and lamina. The rhythms of per and tim expression in the retina and glial cells are similar to that observed in the whole head and in clock neurons, while they differ in the lamina and L2 cells. In both the retina and lamina, CRY seems to be a repressor of clk expression. In L2 interneurons per expression is not cyclic indicating the other function of PER in those cells than in the circadian molecular clock. In contrast to per and tim, the pattern of clk and cry expression is similar in both the retina and lamina. The retina holds the autonomous oscillators but the expression of cry and ccgs, Atpα and nrv2, is also regulated by inputs from the pacemaker transmitted by PDF and ITP neuropeptides. PMID:26441524

  9. Two antagonistic clock-regulated histidine kinases time the activation of circadian gene expression

    PubMed Central

    Gutu, Andrian; O’Shea, Erin K.

    2013-01-01

    Summary The cyanobacterial circadian pacemaker consists of a three-protein clock – KaiA, KaiB and KaiC – that generates oscillations in the phosphorylation state of KaiC. Here we investigate how temporal information encoded in KaiC phosphorylation is transduced to RpaA, a transcription factor required for circadian gene expression. We show that phosphorylation of RpaA is regulated by two antagonistic histidine kinases, SasA and CikA, which are sequentially activated at distinct times by the Kai clock complex. SasA acts as a kinase toward RpaA, whereas CikA, previously implicated in clock input, acts as a phosphatase that dephosphorylates RpaA. CikA and SasA cooperate to generate an oscillation of RpaA activity that is distinct from that generated by either enzyme alone and offset from the rhythm of KaiC phosphorylation. Our observations reveal how circadian clocks can precisely control the timing of output pathways via the concerted action of two oppositely acting enzymes. PMID:23541768

  10. Differential effect of fructose on fat metabolism and clock gene expression in hepatocytes vs. myotubes.

    PubMed

    Chapnik, Nava; Rozenblit-Susan, Sigal; Genzer, Yoni; Froy, Oren

    2016-08-01

    In the liver, fructose bypasses the main rate-limiting step of glycolysis at the level of phosphofructokinase, allowing it to act as an unregulated substrate for de novo lipogenesis. It has been reported that consumption of large amounts of fructose increases de novo lipogenesis in the liver. However, the effect of fructose on ectopic deposition of muscle fat has been under dispute. Our aim was to study the effect of fructose on levels of genes and proteins involved in fatty acid oxidation and synthesis in hepatocytes vs. muscle cells. In addition, as fat accumulation leads to disruption of daily rhythms, we tested the effect of fructose treatment on clock gene expression. AML-12 hepatocytes and C2C12 myotubes were treated with fructose or glucose for 2 consecutive 24-h cycles and harvested every 6h. In contrast to glucose, fructose disrupted clock gene rhythms in hepatocytes, but in myotubes, it led to more robust rhythms. Fructose led to low levels of phosphorylated AMP-activated protein kinase (pAMPK) and high levels of LIPIN1 in hepatocytes compared with glucose. In contrast, fructose led to high pAMPK and low LIPIN1 and microsomal triacylglycerol transfer protein (MTTP) levels in myotubes compared with glucose. Analysis of fat content revealed that fructose led to less fat accumulation in myotubes compared to hepatocytes. In summary, fructose shifts metabolism towards fatty acid synthesis and clock disruption in hepatocytes, but not in myotubes. PMID:27240446

  11. Expression of clock gene in the brain of rainbow trout: comparison with the distribution of melatonin receptors.

    PubMed

    Mazurais, D; Le Dréan, G; Brierley, I; Anglade, I; Bromage, N; Williams, L M; Kah, O

    2000-07-10

    To identify brain structures potentially acting as biological clocks in rainbow trout (Oncorhynchus mykiss), the expression sites of a trout homolog of the mouse clock gene were studied and compared with that of melatonin receptors (Mel-R). For this purpose, a partial sequence of the trout clock gene, including a PAS domain, was obtained by reverse transcription-polymerase chain reaction and used to perform in situ hybridization. The highest density of clock transcripts was observed in the periventricular layer (SPV) of the optic tectum, but a weaker expression was detected in some pretectal nuclei, such as the posterior pretectal nucleus (PO) and the periventricular regions of the diencephalon. Comparison of the hybridization signal in fish sacrificed at 08:00 and 17:00 did not indicate major changes in clock expression levels. Comparison of adjacent sections alternatively treated with clock and Mel-R probes suggests that both messengers are probably expressed in the same cells in the SPV and PO. In addition, in situ hybridization with a glutamate decarboxylase 65 probe, demonstrates that cells expressing clock and Mel-R in the optic tectum are gamma-aminobutyric acid neurons. The tight overlapping between the expression of Mel-R and clock transcripts in cells of the PO and SPV suggests a functional link between these two factors. These results indicate that the optic tectum and the pretectal area of the rainbow trout are major sites of integration of the melatonin signal, express the clock gene, and may act as biological clocks to influence behavioral and endocrine responses in trout. PMID:10861529

  12. All-optical clock extraction from 40-Gbit/s NRZ data using cascaded long-period fiber grating

    NASA Astrophysics Data System (ADS)

    Jeon, Sie-Wook; Hann, Swook; Park, Chang-Soo

    2010-06-01

    All-optical clock extraction from a 40-Gbit/s NRZ input signal is demonstrated using a cascaded long-period fiber grating (CLPG) and a mode-locked fiber ring laser. The CLPG has a Mach-Zehnder configuration with two arms along the core and cladding regions. Using the difference in propagation delay between two arms, the non-return-to-zero (NRZ) signal is converted to the pseudo-return-to-zero (PRZ) signal. To obtain repetitive pulses as a clock signal from the PRZ signal, a ring laser with a semiconductor optical amplifier (SOA) is used. Subsequently, the measured carrier-to-noise ratio (CNR) of the PRZ and clock signals are enhanced up to 30 dB and 31 dB, respectively, compared to that of the original NRZ signal. Also, the clock signal centered at 40 GHz has a low timing jitter of <1.3 ps. It is expected that this method can be applied to high speed fiber-optic systems of >40 Gbit/s due to its small time delay between the core and cladding regions.

  13. Monitoring Alternative Splicing Changes in Arabidopsis Circadian Clock Genes.

    PubMed

    Simpson, Craig G; Fuller, John; Calixto, Cristiane P G; McNicol, Jim; Booth, Clare; Brown, John W S; Staiger, Dorothee

    2016-01-01

    Posttranscriptional control makes an important contribution to circadian regulation of gene expression. In higher plants, alternative splicing is particularly prevalent upon abiotic and biotic stress and in the circadian system. Here we describe in detail a high-resolution reverse transcription-PCR based panel (HR RT-PCR) to monitor alternative splicing events. The use of the panel allows the quantification of changes in the proportion of splice isoforms between different samples, e.g., different time points, different tissues, genotypes, ecotypes, or treatments. PMID:26867620

  14. RORγ directly regulates the circadian expression of clock genes and downstream targets in vivo.

    PubMed

    Takeda, Yukimasa; Jothi, Raja; Birault, Veronique; Jetten, Anton M

    2012-09-01

    In this study, we demonstrate that the lack of retinoic acid-related orphan receptor (ROR) γ or α expression in mice significantly reduced the peak expression level of Cry1, Bmal1, E4bp4, Rev-Erbα and Per2 in an ROR isotype- and tissue-selective manner without affecting the phase of their rhythmic expression. Analysis of RORγ/RORα double knockout mice indicated that in certain tissues RORγ and RORα exhibited a certain degree of redundancy in regulating clock gene expression. Reporter gene analysis showed that RORγ was able to induce reporter gene activity through the RORE-containing regulatory regions of Cry1, Bmal1, Rev-Erbα and E4bp4. Co-expression of Rev-Erbα or addition of a novel ROR antagonist repressed this activation. ChIP-Seq and ChIP-Quantitative real-time polymerase chain reaction (QPCR) analysis demonstrated that in vivo RORγ regulate these genes directly and in a Zeitgeber time (ZT)-dependent manner through these ROREs. This transcriptional activation by RORs was associated with changes in histone acetylation and chromatin accessibility. The rhythmic expression of RORγ1 by clock proteins may lead to the rhythmic expression of RORγ1 target genes. The presence of RORγ binding sites and its down-regulation in RORγ-/- liver suggest that the rhythmic expression of Avpr1a depends on RORγ consistent with the concept that RORγ1 provides a link between the clock machinery and its regulation of metabolic genes. PMID:22753030

  15. The chondrocyte clock gene Bmal1 controls cartilage homeostasis and integrity

    PubMed Central

    Dudek, Michal; Gossan, Nicole; Yang, Nan; Im, Hee-Jeong; Ruckshanthi, Jayalath P.D.; Yoshitane, Hikari; Li, Xin; Jin, Ding; Wang, Ping; Boudiffa, Maya; Bellantuono, Ilaria; Fukada, Yoshitaka; Boot-Handford, Ray P.; Meng, Qing-Jun

    2015-01-01

    Osteoarthritis (OA) is the most prevalent and debilitating joint disease, and there are currently no effective disease-modifying treatments available. Multiple risk factors for OA, such as aging, result in progressive damage and loss of articular cartilage. Autonomous circadian clocks have been identified in mouse cartilage, and environmental disruption of circadian rhythms in mice predisposes animals to OA-like damage. However, the contribution of the cartilage clock mechanisms to the maintenance of tissue homeostasis is still unclear. Here, we have shown that expression of the core clock transcription factor BMAL1 is disrupted in human OA cartilage and in aged mouse cartilage. Furthermore, targeted Bmal1 ablation in mouse chondrocytes abolished their circadian rhythm and caused progressive degeneration of articular cartilage. We determined that BMAL1 directs the circadian expression of many genes implicated in cartilage homeostasis, including those involved in catabolic, anabolic, and apoptotic pathways. Loss of BMAL1 reduced the levels of phosphorylated SMAD2/3 (p-SMAD2/3) and NFATC2 and decreased expression of the major matrix-related genes Sox9, Acan, and Col2a1, but increased p-SMAD1/5 levels. Together, these results define a regulatory mechanism that links chondrocyte BMAL1 to the maintenance and repair of cartilage and suggest that circadian rhythm disruption is a risk factor for joint diseases such as OA. PMID:26657859

  16. Circadian Clock Genes Modulate Human Bone Marrow Mesenchymal Stem Cell Differentiation, Migration and Cell Cycle

    PubMed Central

    Boucher, Helene; Vanneaux, Valerie; Domet, Thomas; Parouchev, Alexandre; Larghero, Jerome

    2016-01-01

    Many of the components that regulate the circadian clock have been identified in organisms and humans. The influence of circadian rhythm (CR) on the regulation of stem cells biology began to be evaluated. However, little is known on the role of CR on human mesenchymal stem cell (hMSCs) properties. The objective of this study was to investigate the influence of CR on the differentiation capacities of bone marrow hMSCs, as well as the regulation of cell cycle and migration capabilities. To that, we used both a chemical approach with a GSK-3β specific inhibitor (2’E,3’Z-6-bromoindirubin-3’-oxime, BIO) and a knockdown of CLOCK and PER2, two of the main genes involved in CR regulation. In these experimental conditions, a dramatic inhibition of adipocyte differentiation was observed, while osteoblastic differentiation capacities were not modified. In addition, cell migration was decreased in PER2-/- cells. Lastly, downregulation of circadian clock genes induced a modification of the hMSCs cell cycle phase distribution, which was shown to be related to a change of the cyclin expression profile. Taken together, these data showed that CR plays a role in the regulation of hMSCs differentiation and division, and likely represent key factor in maintaining hMSCs properties. PMID:26741371

  17. The Mammalian Circadian Clock Gene Per2 Modulates Cell Death in Response to Oxidative Stress

    PubMed Central

    Magnone, Maria Chiara; Langmesser, Sonja; Bezdek, April Candice; Tallone, Tiziano; Rusconi, Sandro; Albrecht, Urs

    2015-01-01

    Living in the earth’s oxygenated environment forced organisms to develop strategies to cope with the damaging effects of molecular oxygen known as reactive oxygen species (ROS). Here, we show that Per2, a molecular component of the mammalian circadian clock, is involved in regulating a cell’s response to oxidative stress. Mouse embryonic fibroblasts (MEFs) containing a mutation in the Per2 gene are more resistant to cytotoxic effects mediated by ROS than wild-type cells, which is paralleled by an altered regulation of bcl-2 expression in Per2 mutant MEFs. The elevated survival rate and alteration of NADH/NAD+ ratio in the mutant cells is reversed by introduction of the wild-type Per2 gene. Interestingly, clock synchronized cells display a time dependent sensitivity to paraquat, a ROS inducing agent. Our observations indicate that the circadian clock is involved in regulating the fate of a cell to survive or to die in response to oxidative stress, which could have implications for cancer development and the aging process. PMID:25628599

  18. Induction of the CLOCK Gene by E2-ERα Signaling Promotes the Proliferation of Breast Cancer Cells

    PubMed Central

    Bi, Hailian; Li, Shujing; Wang, Miao; Xing, Xinrong; Wu, Huijian

    2014-01-01

    Growing genetic and epidemiological evidence suggests a direct connection between the disruption of circadian rhythm and breast cancer. Moreover, the expression of several molecular components constituting the circadian clock machinery has been found to be modulated by estrogen-estrogen receptor α (E2-ERα) signaling in ERα-positive breast cancer cells. In this study, we investigated the regulation of CLOCK expression by ERα and its roles in cell proliferation. Immunohistochemical analysis of human breast tumor samples revealed high expression of CLOCK in ERα-positive breast tumor samples. Subsequent experiments using ERα-positive human breast cancer cell lines showed that both protein and mRNA levels of CLOCK were up-regulated by E2 and ERα. In these cells, E2 promoted the binding of ERα to the EREs (estrogen-response elements) of CLOCK promoter, thereby up-regulating the transcription of CLOCK. Knockdown of CLOCK attenuated cell proliferation in ERα-positive breast cancer cells. Taken together, these results demonstrated that CLOCK could be an important gene that mediates cell proliferation in breast cancer cells. PMID:24789043

  19. THE mPER2 CLOCK GENE MODULATES COCAINE ACTIONS IN THE MOUSE CIRCADIAN SYSTEM

    PubMed Central

    Brager, Allison J.; Stowie, Adam C.; Prosser, Rebecca A.; Glass, J. David

    2014-01-01

    Cocaine is a potent disruptor of photic and non-photic pathways for circadian entrainment of the master circadian clock of the suprachiasmatic nucleus (SCN). These actions of cocaine likely involve its modulation of molecular (clock gene) components for SCN clock timekeeping. At present, however, the physiological basis of such an interaction is unclear. To address this question, we compared photic and non-photic phase-resetting responses between wild-type (WT) and Per2 mutant mice expressing nonfunctional PER2 protein to systemic and intra-SCN cocaine administrations. In the systemic trials, cocaine was administered i.p. (20 mg/kg) either at midday or prior to a light pulse in the early night to assess its non-photic and photic behavioral phase-resetting actions, respectively. In the intra-SCN trial, cocaine was administered by reverse microdialysis at midday to determine if the SCN is a direct target for its non-photic phase-resetting action. Non-photic phase-advancing responses to i.p. cocaine at midday were significantly (~3.5-fold) greater in Per2 mutants than WTs. However, the phase-advancing action of intra-SCN cocaine perfusion at midday did not differ between genotypes. In the light pulse trial, Per2 mutants exhibited larger photic phase-delays than did WTs, and the attenuating action of cocaine on this response was proportionately larger than in WTs. These data indicate that the Per2 clock gene is a potent modulator of cocaine’s actions in the circadian system. With regard to non-photic phase-resetting, the SCN is confirmed as a direct target of cocaine action; however, Per2 modulation of this effect likely occurs outside of the SCN. PMID:23333842

  20. Weight cycling promotes fat gain and altered clock gene expression in adipose tissue in C57BL/6J mice.

    PubMed

    Dankel, S N; Degerud, E M; Borkowski, K; Fjære, E; Midtbø, L K; Haugen, C; Solsvik, M H; Lavigne, A M; Liaset, B; Sagen, J V; Kristiansen, K; Mellgren, G; Madsen, L

    2014-01-15

    Repeated attempts to lose weight by temporary dieting may result in weight cycling, eventually further gain of body fat, and possible metabolic adaptation. We tested this with a controlled experiment in C57BL/6J mice subjected to four weight cycles (WC), continuous hypercaloric feeding (HF), or low-fat feeding (LF). To search for genes involved in an adaptive mechanism to former weight cycling and avoid acute effects of the last cycle, the last hypercaloric feeding period was prolonged by an additional 2 wk before euthanization. Total energy intake was identical in WC and HF. However, compared with HF, the WC mice gained significantly more total body mass and fat mass and showed increased levels of circulating leptin and lipids in liver. Both the HF and WC groups showed increased adipocyte size and insulin resistance. Despite these effects, we also observed an interesting maintenance of circulating adiponectin and free fatty acid levels after WC, whereas changes in these parameters were observed in HF mice. Global gene expression was analyzed by microarrays. Weight-cycled mice were characterized by a downregulation of several clock genes (Dbp, Tef, Per1, Per2, Per3, and Nr1d2) in adipose tissues, which was confirmed by quantitative PCR. In 3T3-L1 cells, we found reduced expression of Dbp and Tef early in adipogenic differentiation, which was mediated via cAMP-dependent signaling. Our data suggest that clock genes in adipose tissue may play a role in metabolic adaptation to weight cycling. PMID:24302006

  1. Time-Dependent Effects of Localized Inflammation on Peripheral Clock Gene Expression in Rats

    PubMed Central

    Westfall, Susan; Aguilar-Valles, Argel; Mongrain, Valérie; Luheshi, Giamal N.; Cermakian, Nicolas

    2013-01-01

    Many aspects of the immune system, including circulating cytokine levels as well as counts and function of various immune cell types, present circadian rhythms. Notably, the mortality rate of animals subjected to high doses of lipopolysaccharide is dependent on the time of treatment. In addition, the severity of symptoms of various inflammatory conditions follows a daily rhythmic pattern. The mechanisms behind the crosstalk between the circadian and immune systems remain elusive. Here we demonstrate that localized inflammation induced by turpentine oil (TURP) causes a time-dependent induction of interleukin (IL)-6 and has time-, gene- and tissue-specific effects on clock gene expression. More precisely, TURP blunts the peak of Per1 and Per2 expression in the liver while in other tissues, the expression nadir is elevated. In contrast, Rev-erbα expression remains relatively unaffected by TURP treatment. Co-treatment with the anti-inflammatory agent IL-1 receptor antagonist (IL-1Ra) did not alter the response of Per2 to TURP treatment in liver, despite the reduced induction of fever and IL-6 serum levels. This indicates that the TURP-mediated changes of Per2 in the liver might be due to factors other than systemic IL-6 and fever. Accordingly, IL-6 treatment had no effect on clock gene expression in HepG2 liver carcinoma cells. Altogether, we show that localized inflammation causes significant time-dependent changes in peripheral circadian clock gene expression, via a mechanism likely involving mediators independent from IL-6 and fever. PMID:23527270

  2. Functional Implications of the CLOCK 3111T/C Single-Nucleotide Polymorphism.

    PubMed

    Ozburn, Angela R; Purohit, Kush; Parekh, Puja K; Kaplan, Gabrielle N; Falcon, Edgardo; Mukherjee, Shibani; Cates, Hannah M; McClung, Colleen A

    2016-01-01

    Circadian rhythm disruptions are prominently associated with bipolar disorder (BD). Circadian rhythms are regulated by the molecular clock, a family of proteins that function together in a transcriptional-translational feedback loop. The CLOCK protein is a key transcription factor of this feedback loop, and previous studies have found that manipulations of the Clock gene are sufficient to produce manic-like behavior in mice (1). The CLOCK 3111T/C single-nucleotide polymorphism (SNP; rs1801260) is a genetic variation of the human CLOCK gene that is significantly associated with increased frequency of manic episodes in BD patients (2). The 3111T/C SNP is located in the 3'-untranslated region of the CLOCK gene. In this study, we sought to examine the functional implications of the human CLOCK 3111T/C SNP by transfecting a mammalian cell line (mouse embryonic fibroblasts isolated from Clock(-/-) knockout mice) with pcDNA plasmids containing the human CLOCK gene with either the T or C SNP at position 3111. We then measured circadian gene expression over a 24-h time period. We found that the CLOCK3111C SNP resulted in higher mRNA levels than the CLOCK 3111T SNP. Furthermore, we found that Per2, a transcriptional target of CLOCK, was also more highly expressed with CLOCK 3111C expression, indicating that the 3'-UTR SNP affects the expression, function, and stability of CLOCK mRNA. PMID:27148095

  3. Temporal transcriptomics suggest that twin-peaking genes reset the clock

    PubMed Central

    Pembroke, William G; Babbs, Arran; Davies, Kay E; Ponting, Chris P; Oliver, Peter L

    2015-01-01

    The mammalian suprachiasmatic nucleus (SCN) drives daily rhythmic behavior and physiology, yet a detailed understanding of its coordinated transcriptional programmes is lacking. To reveal the finer details of circadian variation in the mammalian SCN transcriptome we combined laser-capture microdissection (LCM) and RNA-seq over a 24 hr light / dark cycle. We show that 7-times more genes exhibited a classic sinusoidal expression signature than previously observed in the SCN. Another group of 766 genes unexpectedly peaked twice, near both the start and end of the dark phase; this twin-peaking group is significantly enriched for synaptic transmission genes that are crucial for light-induced phase shifting of the circadian clock. 341 intergenic non-coding RNAs, together with novel exons of annotated protein-coding genes, including Cry1, also show specific circadian expression variation. Overall, our data provide an important chronobiological resource (www.wgpembroke.com/shiny/SCNseq/) and allow us to propose that transcriptional timing in the SCN is gating clock resetting mechanisms. DOI: http://dx.doi.org/10.7554/eLife.10518.001 PMID:26523393

  4. Peripheral circadian clocks--a conserved phenotype?

    PubMed

    Weigl, Yuval; Harbour, Valerie L; Robinson, Barry; Dufresne, Line; Amir, Shimon

    2013-05-01

    The circadian system of mammals regulates the timing of occurrence of behavioral and physiological events, thereby optimizing adaptation to their surroundings. This system is composed of a single master pacemaker located in the suprachiasmatic nucleus (SCN) and a population of peripheral clocks. The SCN integrates time information from exogenous sources and, in turn, synchronizes the downstream peripheral clocks. It is assumed that under normal conditions, the circadian phenotype of different peripheral clocks would be conserved with respect to its period and robustness. To study this idea, we measured the daily wheel-running activity (WRA; a marker of the SCN output) in 84 male inbred LEW/Crl rats housed under a 12 h:12 h light-dark cycle. In addition, we assessed the mRNA expression of two clock genes, rPer2 and rBmal1, and one clock-controlled gene, rDbp, in four tissues that have the access to time cues other than those emanating from the SCN: olfactory bulbs (OBs), liver, tail skin, and white blood cells (WBCs). In contrast with the assumption stated above, we found that circadian clocks in peripheral tissues differ in the temporal pattern of the expression of circadian clock genes, in the robustness of the rhythms, and possibly in the number of functional ~24-h-clock cells. Based on the tissue diversity in the robustness of the clock output, the hepatic clock is likely to house the highest number of functional ~24-h-clock cells, and the OBs, the fewest number. Thus, the phenotype of the circadian clock in the periphery is tissue specific and may depend not only on the SCN but also on the sensitivity of the tissue to non-SCN-derived time cues. In the OBs and liver, the circadian clock phenotypes seem to be dominantly shaped by the SCN output. However, in the tail skin and WBC, other time cues participate in the phenotype design. Finally, our study suggests that the basic phenotype of the circadian clock is constructed at the transcript level of the core clock

  5. Synergistic regulation of the mouse orphan nuclear receptor SHP gene promoter by CLOCK-BMAL1 and LRH-1

    SciTech Connect

    Oiwa, Ako; Kakizawa, Tomoko . E-mail: tkaki@hsp.md.shinshu-u.ac.jp; Miyamoto, Takahide; Yamashita, Koh; Jiang, Wei; Takeda, Teiji; Suzuki, Satoru; Hashizume, Kiyoshi

    2007-02-23

    Small heterodimer partner (SHP; NR0B2) is an orphan nuclear receptor and acts as a repressor for wide variety of nuclear hormone receptors. We demonstrated here that mouse SHP mRNA showed a circadian expression pattern in the liver. Transient transfection of the mSHP promoter demonstrated that CLOCK-BMAL1, core circadian clock components, bound to E-box (CACGTG), and stimulated the promoter activity by 4-fold. Liver receptor homologue-1 (LRH-1; NR5A2) stimulated the mSHP promoter, and CLOCK-BMAL1 synergistically enhanced the LRH-1-mediated transactivation. Interestingly, SHP did not affect the CLOCK-BMAL1-mediated promoter activity, but strongly repressed the synergistic activation of CLOCK-BMAL1 and LRH-1. Furthermore, in vitro pull-down assays revealed the existence of direct protein-protein interaction between LRH-1 and CLOCK. In summary, this study shows that CLOCK-BMAL1, LRH-1 and SHP coordinately regulate the mSHP gene to generate the circadian oscillation. The cyclic expression of mSHP may affect daily activity of other nuclear receptors and contribute to circadian liver functions.

  6. Clock genes and their genomic distributions in three species of salmonid fishes: Associations with genes regulating sexual maturation and cell cycling

    PubMed Central

    2010-01-01

    Background Clock family genes encode transcription factors that regulate clock-controlled genes and thus regulate many physiological mechanisms/processes in a circadian fashion. Clock1 duplicates and copies of Clock3 and NPAS2-like genes were partially characterized (genomic sequencing) and mapped using family-based indels/SNPs in rainbow trout (RT)(Oncorhynchus mykiss), Arctic charr (AC)(Salvelinus alpinus), and Atlantic salmon (AS)(Salmo salar) mapping panels. Results Clock1 duplicates mapped to linkage groups RT-8/-24, AC-16/-13 and AS-2/-18. Clock3/NPAS2-like genes mapped to RT-9/-20, AC-20/-43, and AS-5. Most of these linkage group regions containing the Clock gene duplicates were derived from the most recent 4R whole genome duplication event specific to the salmonids. These linkage groups contain quantitative trait loci (QTL) for life history and growth traits (i.e., reproduction and cell cycling). Comparative synteny analyses with other model teleost species reveal a high degree of conservation for genes in these chromosomal regions suggesting that functionally related or co-regulated genes are clustered in syntenic blocks. For example, anti-müllerian hormone (amh), regulating sexual maturation, and ornithine decarboxylase antizymes (oaz1 and oaz2), regulating cell cycling, are contained within these syntenic blocks. Conclusions Synteny analyses indicate that regions homologous to major life-history QTL regions in salmonids contain many candidate genes that are likely to influence reproduction and cell cycling. The order of these genes is highly conserved across the vertebrate species examined, and as such, these genes may make up a functional cluster of genes that are likely co-regulated. CLOCK, as a transcription factor, is found within this block and therefore has the potential to cis-regulate the processes influenced by these genes. Additionally, clock-controlled genes (CCGs) are located in other life-history QTL regions within salmonids suggesting that

  7. C-H activation generates period-shortening molecules that target cryptochrome in the mammalian circadian clock.

    PubMed

    Oshima, Tsuyoshi; Yamanaka, Iori; Kumar, Anupriya; Yamaguchi, Junichiro; Nishiwaki-Ohkawa, Taeko; Muto, Kei; Kawamura, Rika; Hirota, Tsuyoshi; Yagita, Kazuhiro; Irle, Stephan; Kay, Steve A; Yoshimura, Takashi; Itami, Kenichiro

    2015-06-01

    The synthesis and functional analysis of KL001 derivatives, which are modulators of the mammalian circadian clock, are described. By using cutting-edge C-H activation chemistry, a focused library of KL001 derivatives was rapidly constructed, which enabled the identification of the critical sites on KL001 derivatives that induce a rhythm-changing activity along with the components that trigger opposite modes of action. The first period-shortening molecules that target the cryptochrome (CRY) were thus discovered. Detailed studies on the effects of these compounds on CRY stability implicate the existence of an as yet undiscovered regulatory mechanism. PMID:25960183

  8. Placental genetic variations in circadian clock-related genes increase the risk of placental abruption

    PubMed Central

    Qiu, Chunfang; Gelaye, Bizu; Denis, Marie; Tadesse, Mahlet G; Enquobahrie, Daniel A; Ananth, Cande V; Pacora, Percy N; Salazar, Manuel; Sanchez, Sixto E; Williams, Michelle A

    2016-01-01

    The genetic architecture of placental abruption (PA) remains poorly understood. We examined variations in SNPs of circadian clock-related genes in placenta with PA risk. We also explored placental and maternal genomic contributions to PA risk. Placental genomic DNA samples were isolated from 280 PA cases and 244 controls. Genotyping was performed using the Illumina Cardio-MetaboChip. We examined 116 SNPs in 13 genes known to moderate circadian rhythms. Logistic regression models were fit to estimate odds ratios (ORs). The combined effect of multiple SNPs on PA risk was estimated using a weighted genetic risk score. We examined independent and joint associations of wGRS derived from placental and maternal genomes with PA. Seven SNPs in five genes (ARNTL2, CRY2, DEC1, PER3 and RORA), in the placental genome, were associated with PA risk. Each copy of the minor allele (G) of a SNP in the RORA gene (rs2899663) was associated with a 30% reduced odds of PA (95% CI 0.52-0.95). The odds of PA increased with increasing placental-wGRS (Ptrend<0.001). The ORs were 1.00, 2.16, 3.24 and 4.48 across quartiles. Associations persisted after the maternal-wGRS was included in the model. There was evidence of an additive contribution of placental and maternal genetic contributions to PA risk. Participants with placental- and maternal-wGRS in the highest quartile, compared with those in the lowest quartile, had a 15.57-fold (95% CI 3.34-72.60) increased odds of PA. Placental variants in circadian clock-related genes are associated with PA risk; and the association persists after control of genetic variants in the maternal genome. PMID:27186326

  9. Functional Implications of the CLOCK 3111T/C Single-Nucleotide Polymorphism

    PubMed Central

    Ozburn, Angela R.; Purohit, Kush; Parekh, Puja K.; Kaplan, Gabrielle N.; Falcon, Edgardo; Mukherjee, Shibani; Cates, Hannah M.; McClung, Colleen A.

    2016-01-01

    Circadian rhythm disruptions are prominently associated with bipolar disorder (BD). Circadian rhythms are regulated by the molecular clock, a family of proteins that function together in a transcriptional–translational feedback loop. The CLOCK protein is a key transcription factor of this feedback loop, and previous studies have found that manipulations of the Clock gene are sufficient to produce manic-like behavior in mice (1). The CLOCK 3111T/C single-nucleotide polymorphism (SNP; rs1801260) is a genetic variation of the human CLOCK gene that is significantly associated with increased frequency of manic episodes in BD patients (2). The 3111T/C SNP is located in the 3′-untranslated region of the CLOCK gene. In this study, we sought to examine the functional implications of the human CLOCK 3111T/C SNP by transfecting a mammalian cell line (mouse embryonic fibroblasts isolated from Clock−/− knockout mice) with pcDNA plasmids containing the human CLOCK gene with either the T or C SNP at position 3111. We then measured circadian gene expression over a 24-h time period. We found that the CLOCK3111C SNP resulted in higher mRNA levels than the CLOCK 3111T SNP. Furthermore, we found that Per2, a transcriptional target of CLOCK, was also more highly expressed with CLOCK 3111C expression, indicating that the 3′-UTR SNP affects the expression, function, and stability of CLOCK mRNA. PMID:27148095

  10. Period-2 cycles and 2:1 phase locking in a biological clock driven by temperature pulses.

    PubMed

    Hütt, M-Th; Rascher, U; Beck, F; Lüttge, U

    2002-08-01

    Crassulacean acid metabolism (CAM) serves as a botanical model system for the investigation of circadian rhythmicity. In a new set of experiments with the obligatory CAM plant Kalanchoë daigremontiana the response to periodic stimulations with temperature pulses has been studied. On the basis of an experimental phase-response curve of net CO(2)-gas exchange the effect of periodic stimulation has been simulated using a finite-difference equation. These simulations revealed the locations of two period-2 cycles in the CO(2) uptake of the CAM plant. In subsequent experiments based upon the simulated bifurcation diagram the position and amplitude of one of these cycles were confirmed, while experimental evidence for the second cycle could be found. Possible roles of such dynamics for the functioning of the biological clock are discussed. PMID:12270281

  11. Defining the robust behaviour of the plant clock gene circuit with absolute RNA timeseries and open infrastructure

    PubMed Central

    Flis, Anna; Fernández, Aurora Piñas; Zielinski, Tomasz; Mengin, Virginie; Sulpice, Ronan; Stratford, Kevin; Hume, Alastair; Pokhilko, Alexandra; Southern, Megan M.; Seaton, Daniel D.; McWatters, Harriet G.; Stitt, Mark; Halliday, Karen J.; Millar, Andrew J.

    2015-01-01

    Our understanding of the complex, transcriptional feedback loops in the circadian clock mechanism has depended upon quantitative, timeseries data from disparate sources. We measure clock gene RNA profiles in Arabidopsis thaliana seedlings, grown with or without exogenous sucrose, or in soil-grown plants and in wild-type and mutant backgrounds. The RNA profiles were strikingly robust across the experimental conditions, so current mathematical models are likely to be broadly applicable in leaf tissue. In addition to providing reference data, unexpected behaviours included co-expression of PRR9 and ELF4, and regulation of PRR5 by GI. Absolute RNA quantification revealed low levels of PRR9 transcripts (peak approx. 50 copies cell−1) compared with other clock genes, and threefold higher levels of LHY RNA (more than 1500 copies cell−1) than of its close relative CCA1. The data are disseminated from BioDare, an online repository for focused timeseries data, which is expected to benefit mechanistic modelling. One data subset successfully constrained clock gene expression in a complex model, using publicly available software on parallel computers, without expert tuning or programming. We outline the empirical and mathematical justification for data aggregation in understanding highly interconnected, dynamic networks such as the clock, and the observed design constraints on the resources required to make this approach widely accessible. PMID:26468131

  12. Defining the robust behaviour of the plant clock gene circuit with absolute RNA timeseries and open infrastructure.

    PubMed

    Flis, Anna; Fernández, Aurora Piñas; Zielinski, Tomasz; Mengin, Virginie; Sulpice, Ronan; Stratford, Kevin; Hume, Alastair; Pokhilko, Alexandra; Southern, Megan M; Seaton, Daniel D; McWatters, Harriet G; Stitt, Mark; Halliday, Karen J; Millar, Andrew J

    2015-10-01

    Our understanding of the complex, transcriptional feedback loops in the circadian clock mechanism has depended upon quantitative, timeseries data from disparate sources. We measure clock gene RNA profiles in Arabidopsis thaliana seedlings, grown with or without exogenous sucrose, or in soil-grown plants and in wild-type and mutant backgrounds. The RNA profiles were strikingly robust across the experimental conditions, so current mathematical models are likely to be broadly applicable in leaf tissue. In addition to providing reference data, unexpected behaviours included co-expression of PRR9 and ELF4, and regulation of PRR5 by GI. Absolute RNA quantification revealed low levels of PRR9 transcripts (peak approx. 50 copies cell(-1)) compared with other clock genes, and threefold higher levels of LHY RNA (more than 1500 copies cell(-1)) than of its close relative CCA1. The data are disseminated from BioDare, an online repository for focused timeseries data, which is expected to benefit mechanistic modelling. One data subset successfully constrained clock gene expression in a complex model, using publicly available software on parallel computers, without expert tuning or programming. We outline the empirical and mathematical justification for data aggregation in understanding highly interconnected, dynamic networks such as the clock, and the observed design constraints on the resources required to make this approach widely accessible. PMID:26468131

  13. Interaction of growth hormone overexpression and nutritional status on pituitary gland clock gene expression in coho salmon, Oncorhynchus kisutch.

    PubMed

    Kim, Jin-Hyoung; White, Samantha L; Devlin, Robert H

    2015-02-01

    Clock genes are involved in generating a circadian rhythm that is integrated with the metabolic state of an organism and information from the environment. Growth hormone (GH) transgenic coho salmon, Oncorhynchus kisutch, show a large increase in growth rate, but also attenuated seasonal growth modulations, modified timing of physiological transformations (e.g. smoltification) and disruptions in pituitary gene expression compared with wild-type salmon. In several fishes, circadian rhythm gene expression has been found to oscillate in the suprachiasmatic nucleus of the hypothalamus, as well as in multiple peripheral tissues, but this control system has not been examined in the pituitary gland nor has the effect of transgenic growth modification been examined. Thus, the daily expression of 10 core clock genes has been examined in pituitary glands of GH transgenic (T) and wild-type coho salmon (NT) entrained on a regular photocycle (12L: 12D) and provided either with scheduled feeding or had food withheld for 60 h. Most clock genes in both genotypes showed oscillating patterns of mRNA levels with light and dark cycles. However, T showed different amplitudes and patterns of expression compared with wild salmon, both in fed and starved conditions. The results from this study indicate that constitutive expression of GH is associated with changes in clock gene regulation, which may play a role in the disrupted behavioural and physiological phenotypes observed in growth-modified transgenic strains. PMID:25222344

  14. Existence of a photoinducible phase for ovarian development and photoperiod-related alteration of clock gene expression in a damselfish.

    PubMed

    Takeuchi, Yuki; Hada, Noriko; Imamura, Satoshi; Hur, Sung-Pyo; Bouchekioua, Selma; Takemura, Akihiro

    2015-10-01

    The sapphire devil, Chrysiptera cyanea, is a reef-associated damselfish and their ovarian development can be induced by a long photoperiod. In this study, we demonstrated the existence of a photoinducible phase for the photoperiodic ovarian development in the sapphire devil. Induction of ovarian development under night-interruption light schedules and Nanda-Hamner cycles revealed that the photoinducible phase appeared in a circadian manner between ZT12 and ZT13. To characterize the effect of photoperiod on clock gene expression in the brain of this species, we determined the expression levels of the sdPer1, sdPer2, sdCry1, and sdCry2 clock genes under constant light and dark conditions (LL and DD) and photoperiodic (short and long photoperiods). The expression of sdPer1 exhibited clear circadian oscillation under both LL and DD conditions, while sdPer2 and sdCry1 expression levels were lower under DD than under LL conditions and sdCry2 expression was lower under LL than under DD conditions. These results suggest a key role for sdPer1 in circadian clock cycling and that sdPer2, sdCry1, and sdCry2 are light-responsive clock genes in the sapphire devil. After 1 week under a long photoperiod, we observed photoperiod-related changes in sdPer1, sdPer2, and sdCry2 expression, but not in sdCry1 expression. These results suggest that the expression patterns of some clock genes exhibit seasonal variation according to seasonal changes in day length and that such seasonal alteration of clock gene expression may contribute to seasonal recognition by the sapphire devil. PMID:26093172

  15. Disruption of the circadian clock within the cardiomyocyte influences mycardial contractile function, metabolism, and gene expression

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Virtually every mammalian cell, including cardiomyocytes, possesses an intrinsic circadian clock. The role of this transcriptionally based molecular mechanism in cardiovascular biology is poorly understood. We hypothesized that the circadian clock within the cardiomyocyte influences diurnal variatio...

  16. The intrinsic circadian clock within the cardiomyocyte directly regulates myocardial gene expression, metabolism, and contractile function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Virtually every mammalian cell, including cardiomyocytes, possesses an intrinsic circadian clock. The role of this transcriptionally based molecular mechanism in cardiovascular biology remains unknown. We hypothesized that the circadian clock within the cardiomyocyte plays a role in regulating myo...

  17. The intrinsic circadian clock within the cardiomyocyte directly regulates myocardial gene expression, metabolism, and contractile function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Virtually every mammalian cell, including cardiomyocytes, possesses an intrinsic circadian clock. The role of this transcriptionally based molecular mechanism in cardiovascular biology remains unknown. We hypothesized that circadian clock within the cardiomyocyte plays a role in regulating myocardia...

  18. Involvement of 5-HT₃ and 5-HT₄ receptors in the regulation of circadian clock gene expression in mouse small intestine.

    PubMed

    Aoki, Natsumi; Watanabe, Hiroyuki; Okada, Kazuya; Aoki, Kazuyuki; Imanishi, Takuma; Yoshida, Daisuke; Ishikawa, Ryosuke; Shibata, Shigenobu

    2014-01-01

    Several lines of evidence suggest that 5-HT receptors play a critical role in the expression of clock genes in the suprachiasmatic nucleus, the main circadian oscillator in hamsters. The contributions of 5-HT-receptor subtypes in the intestine, where they are expressed at high concentrations, are however not yet clarified. The 5-HT synthesis inhibitor, p-chlorophenylalanine, attenuated the daily rhythm of Per1 and Per2 gene expression in the intestine. Injection of 5-HT and agonists of the 5-HT3 and 5-HT4 receptors increased Per1/Per2 expression and decreased Bmal1 expression in a dose-dependent manner. Although treatment with antagonists of 5-HT3 and 5-HT4 alone did not affect clock gene expression, co-injection of these antagonists with 5-HT blocked the 5-HT-induced changes in clock gene expression. Increased tissue levels of 5-HT due to treatment with the antidepressants clomipramine and fluvoxamine did not affect clock gene expression. The present results suggest that the 5-HT system in the small intestine may play a critical role in regulating circadian rhythms through 5-HT3/5-HT4-receptor activation. PMID:24492464

  19. A latitudinal cline in the Chinook salmon (Oncorhynchus tshawytscha) Clock gene: evidence for selection on PolyQ length variants

    PubMed Central

    O'Malley, Kathleen G; Banks, Michael A

    2008-01-01

    A critical seasonal event for anadromous Chinook salmon (Oncorhynchus tshawytscha) is the time at which adults migrate from the ocean to breed in freshwater. We investigated whether allelic variation at the circadian rhythm genes, OtsClock1a and OtsClock1b, underlies genetic control of migration timing among 42 populations in North America. We identified eight length variants of the functionally important polyglutamine repeat motif (PolyQ) of OtsClock1b while OtsClock1a PolyQ was highly conserved. We found evidence of a latitudinal cline in average allele length and frequency of the two most common OtsClock1b alleles. The shorter 335 bp allele increases in frequency with decreasing latitude while the longer 359 bp allele increases in frequency at higher latitudes. Comparison to 13 microsatellite loci showed that 335 and 359 bp deviate significantly from neutral expectations. Furthermore, a hierarchical gene diversity analysis based on OtsClock1b PolyQ variation revealed that run timing explains 40.9 per cent of the overall genetic variance among populations. By contrast, an analysis based on 13 microsatellite loci showed that run timing explains only 13.2 per cent of the overall genetic variance. Our findings suggest that length polymorphisms in OtsClock1b PolyQ may be maintained by selection and reflect an adaptation to ecological factors correlated with latitude, such as the seasonally changing day length. PMID:18713722

  20. Differential regulation of two period genes in the Xenopus eye.

    PubMed

    Zhuang, M; Wang, Y; Steenhard, B M; Besharse, J C

    2000-10-20

    The recent identification and analysis of mammalian homologues of the well characterized Drosophila circadian clock gene, Period (Per), has led to the idea that key features of vertebrate circadian rhythmicity are conserved at the molecular level. The Xenopus laevis retina contains a circadian clock mechanism that can be studied in vitro. To study the rhythmic expression of Per in the Xenopus retina, we used a degenerate RT-PCR strategy to obtain cDNA clones covering the entire 1427 amino acid coding region of a Xenopus homologue of Per2 and a partial cDNA sequence for a Xenopus homologue of Per1. Northern blot analysis shows that xPer1 and xPer2 transcripts are expressed most abundantly in the eye and the brain. However, rhythmic expression of xPer2 transcripts in the retina and retinal pigment epithelium (RPE) is light dependent and occurs only under 12 h light/12 h dark (LD) conditions, not in constant dark (DD). In contrast, xPer1 mRNA accumulation is rhythmic under both LD and DD conditions. Light dependent regulation of xPer2 mRNA and circadian regulation of xPer1 mRNA in the Xenopus retina differs from that in Drosophila and mammals. Light dependence of xPer2 mRNA levels and the offset phase relationship of the xPer2 rhythm to that for xPer1 suggests a role for xPer2 in circadian entrainment. PMID:11042357

  1. The methamphetamine-sensitive circadian oscillator does not employ canonical clock genes.

    PubMed

    Mohawk, Jennifer A; Baer, Matthew L; Menaker, Michael

    2009-03-01

    The "master clock" in the suprachiasmatic nucleus (SCN) of the hypothalamus controls most behavioral, physiological, and molecular circadian rhythms in mammals. However, there are other, still unidentified, circadian oscillators that are able to carry out some SCN functions. Here we show that one of these, the methamphetamine-sensitive circadian oscillator (MASCO), which generates behavioral rhythms in the absence of the SCN, is based on an entirely different molecular mechanism. We tested mice lacking, or with mutations of, genes that form the canonical circadian machinery. In all cases, animals that were arrhythmic as a consequence of genetic defect expressed circadian locomotor rhythms when treated with methamphetamine. These results strongly support the hypothesis that the mechanism generating MASCO does not involve the molecular feedback loops that underlie canonical circadian rhythmicity. The properties of MASCO may provide insight into the evolution of circadian mechanisms. Importantly, MASCO may play a role in addiction to psychostimulants. PMID:19204282

  2. Differential maturation of circadian rhythms in clock gene proteins in the suprachiasmatic nucleus and the pars tuberalis during mouse ontogeny

    PubMed Central

    Ansari, Nariman; Agathagelidis, Manuel; Lee, Choogon; Korf, Horst-Werner; von Gall, Charlotte

    2009-01-01

    Circadian rhythms of many body functions in mammals are controlled by a master pacemaker residing in the hypothalamic suprachiasmatic nucleus (SCN) that synchronises peripheral oscillators. The SCN and peripheral oscillators share several components of the molecular clockwork and comprise transcriptional activators (BMAL1 and CLOCK/NPAS2) and inhibitors (mPER1/2 and mCRY1/2). Here we compared the ontogenetic maturation of the clockwork in the SCN and pars tuberalis (PT). The PT is a peripheral oscillator that strongly depends on rhythmic melatonin signals. Immunoreactions for clock gene proteins were determined in the SCN and PT at four different timepoints during four differential stages of mouse ontogeny: foetal (embryonic day 18), newborn (2-day-old), infantile (10-day-old), and adult. In the foetal SCN levels of immunoreactions of all clock proteins were significantly lower as compared to adult levels except for BMAL1. In the newborn SCN the clock protein immunoreactions had not yet reached adult levels, but the infantile SCN showed similar levels of immunreactions as the adult. In contrast, immunoreactions for all clock gene proteins in the foetal PT were as intense as in newborn, infantile, and adult and showed the same phase. As the foetal pineal gland is not yet capable of rhythmic melatonin production, the rhythms in clock gene proteins in the foetal PT are presumably dependent on the maternal melatonin signal. Thus, our data provide the first evidence that maternal melatonin is important for establishing and maintaining circadian rhythms in a foetal peripheral oscillator. PMID:19222558

  3. Differential maturation of circadian rhythms in clock gene proteins in the suprachiasmatic nucleus and the pars tuberalis during mouse ontogeny.

    PubMed

    Ansari, Nariman; Agathagelidis, Manuel; Lee, Choogon; Korf, Horst-Werner; von Gall, Charlotte

    2009-02-01

    Circadian rhythms of many body functions in mammals are controlled by a master pacemaker, residing in the hypothalamic suprachiasmatic nucleus (SCN), which synchronises peripheral oscillators. The SCN and peripheral oscillators share several components of the molecular clockwork and comprise transcriptional activators (BMAL1 and CLOCK/NPAS2) and inhibitors (mPER1/2 and mCRY1/2). Here we compared the ontogenetic maturation of the clockwork in the SCN and pars tuberalis (PT). The PT is a peripheral oscillator that strongly depends on rhythmic melatonin signals. Immunoreactions for clock gene proteins were determined in the SCN and PT at four different timepoints during four differential stages of mouse ontogeny: foetal (embryonic day 18), newborn (2-day-old), infantile (10-day-old), and adult. In the foetal SCN, levels of immunoreactions of all clock proteins were significantly lower than adult levels except for BMAL1. In the newborn SCN the clock protein immunoreactions had not yet reached adult levels, but the infantile SCN showed similar levels of immunoreactions as the adult. In contrast, immunoreactions for all clock gene proteins in the foetal PT were as intense as in newborn, infantile and adult, and showed the same phase. As the foetal pineal gland is not yet capable of rhythmic melatonin production, the rhythms in clock gene proteins in the foetal PT are presumably dependent on the maternal melatonin signal. Thus, our data provide the first evidence that maternal melatonin is important for establishing and maintaining circadian rhythms in a foetal peripheral oscillator. PMID:19222558

  4. The clock gene PER1 suppresses expression of tumor-related genes in human oral squamous cell carcinoma

    PubMed Central

    Li, Han-Xue; Fu, Xiao-Juan; Yang, Kai; Chen, Dan; Tang, Hong; Zhao, Qin

    2016-01-01

    Abnormal expression of the clock gene PER1 is highly correlated with carcinogenesis and the development of malignant tumors. Here, we designed short hairpin RNAs (shRNAs) to effectively knock down PER1 in SCC15 human oral squamous cell carcinoma cells. shRNA-mediated PER1 knockdown promoted SCC15 cell growth, proliferation, apoptosis resistance, migration and invasion in vitro. PER1 knockdown also increased the cells' expression of KI-67, MDM2, BCL-2, MMP2 and MMP9 mRNA, and decreased expression of C-MYC, p53, BAX and TIMP-2. In BALB/c nu/nu nude mice subcutaneously injected with SCC15 cells, PER1 knockdown in the cells enhanced tumor development, leading to increased tumor weights and volumes. These results suggest that PER1 is an important tumor suppressor gene and may be a useful molecular target for the treatment of cancer. PMID:26943040

  5. Smith-Magenis Syndrome Results in Disruption of CLOCK Gene Transcription and Reveals an Integral Role for RAI1 in the Maintenance of Circadian Rhythmicity

    PubMed Central

    Williams, Stephen R.; Zies, Deborah; Mullegama, Sureni V.; Grotewiel, Michael S.; Elsea, Sarah H.

    2012-01-01

    Haploinsufficiency of RAI1 results in Smith-Magenis syndrome (SMS), a disorder characterized by intellectual disability, multiple congenital anomalies, obesity, neurobehavioral abnormalities, and a disrupted circadian sleep-wake pattern. An inverted melatonin rhythm (i.e., melatonin peaks during the day instead of at night) and associated sleep-phase disturbances in individuals with SMS, as well as a short-period circadian rhythm in mice with a chromosomal deletion of Rai1, support SMS as a circadian-rhythm-dysfunction disorder. However, the molecular cause of the circadian defect in SMS has not been described. The circadian oscillator temporally orchestrates metabolism, physiology, and behavior largely through transcriptional modulation. Data support RAI1 as a transcriptional regulator, but the genes it might regulate are largely unknown. Investigation into the role that RAI1 plays in the regulation of gene transcription and circadian maintenance revealed that RAI1 regulates the transcription of circadian locomotor output cycles kaput (CLOCK), a key component of the mammalian circadian oscillator that transcriptionally regulates many critical circadian genes. Data further show that haploinsufficiency of RAI1 and Rai1 in SMS fibroblasts and the mouse hypothalamus, respectively, results in the transcriptional dysregulation of the circadian clock and causes altered expression and regulation of multiple circadian genes, including PER2, PER3, CRY1, BMAL1, and others. These data suggest that heterozygous mutation of RAI1 and Rai1 leads to a disrupted circadian rhythm and thus results in an abnormal sleep-wake cycle, which can contribute to an abnormal feeding pattern and dependent cognitive performance. Finally, we conclude that RAI1 is a positive transcriptional regulator of CLOCK, pinpointing a novel and important role for this gene in the circadian oscillator. PMID:22578325

  6. Modulation of learning and memory by the targeted deletion of the circadian clock gene Bmal1 in forebrain circuits.

    PubMed

    Snider, Kaitlin H; Dziema, Heather; Aten, Sydney; Loeser, Jacob; Norona, Frances E; Hoyt, Kari; Obrietan, Karl

    2016-07-15

    A large body of literature has shown that the disruption of circadian clock timing has profound effects on mood, memory and complex thinking. Central to this time keeping process is the master circadian pacemaker located within the suprachiasmatic nucleus (SCN). Of note, within the central nervous system, clock timing is not exclusive to the SCN, but rather, ancillary oscillatory capacity has been detected in a wide range of cell types and brain regions, including forebrain circuits that underlie complex cognitive processes. These observations raise questions about the hierarchical and functional relationship between the SCN and forebrain oscillators, and, relatedly, about the underlying clock-gated synaptic circuitry that modulates cognition. Here, we utilized a clock knockout strategy in which the essential circadian timing gene Bmal1 was selectively deleted from excitatory forebrain neurons, whilst the SCN clock remained intact, to test the role of forebrain clock timing in learning, memory, anxiety, and behavioral despair. With this model system, we observed numerous effects on hippocampus-dependent measures of cognition. Mice lacking forebrain Bmal1 exhibited deficits in both acquisition and recall on the Barnes maze. Notably, loss of forebrain Bmal1 abrogated time-of-day dependent novel object location memory. However, the loss of Bmal1 did not alter performance on the elevated plus maze, open field assay, and tail suspension test, indicating that this phenotype specifically impairs cognition but not affect. Together, these data suggest that forebrain clock timing plays a critical role in shaping the efficiency of learning and memory retrieval over the circadian day. PMID:27091299

  7. Melatonin biosynthesizing enzyme genes and clock genes in ovary and whole brain of zebrafish (Danio rerio): Differential expression and a possible interplay.

    PubMed

    Khan, Zeeshan Ahmad; Yumnamcha, Thangal; Rajiv, Chongtham; Devi, Haobijam Sanjita; Mondal, Gopinath; Devi, Sh Dharmajyoti; Bharali, Rupjyoti; Chattoraj, Asamanja

    2016-07-01

    The present study on zebrafish (Danio rerio) is the first attempt to demonstrate the circadian mRNA expression of melatonin biosynthesizing enzyme genes (Tph1a, Aanat1, Aanat2 and Hiomt) and clock associated genes (Bmal1a, Clock1a, Per1b, Per2 and Cry2a) in the ovary with a comparison to whole brain in normal (LD=12h L:12h D) and altered photic conditions (continuous dark, DD; continuous light, LL). Moreover, the present study also confirmed the ability of zebrafish ovary to biosynthesize melatonin both in vivo and in vitro with a significant difference at day and night. qRT-PCR analysis of genes revealed a dark acrophase of Aanat2 in both organs while Tph1 is in whole brain in LD condition. On the contrary, Bmal1a and Clock1a giving their peak in light, thereby showing a negative correlation with Tph1a and Aanat2. In LD-ovary, the acrophase of Tph1a, Bmal1a and Clock1a is in light and thus display a positive correlation. This trend of relationship in respect to Tph1a is not changing in altered photic conditions in both organs (except in DD-ovary). On the other hand this association for Aanat2 is varying in ovary under altered photic conditions but only in DD-whole brain. Both in LD and LL the expression of Aanat2 in brain presenting an opposite acrophase with both Bmal1a and Clock1a of ovary and consequently displaying a strong negative correlation among them. Interestingly, all ovarian clock associated genes become totally arrhythmic in DD, representing a loss of correlation between the melatonin synthesizing genes in brain and clock associated genes in ovary. The result is also indicating the formation of two heterodimers namely Clock1a:Bmal1a and Per2:Cry2a in the functioning of clock genes in both organs, irrespective of photic conditions, as they are exhibiting a strong significant positive correlation. Collectively, our data suggest that ovary of zebrafish is working as peripheral oscillator having its own melatonin biosynthesizing machinery and signifying a

  8. Conserved and Divergent Rhythms of Crassulacean Acid Metabolism-Related and Core Clock Gene Expression in the Cactus Opuntia ficus-indica1[C][W

    PubMed Central

    Mallona, Izaskun; Egea-Cortines, Marcos; Weiss, Julia

    2011-01-01

    The cactus Opuntia ficus-indica is a constitutive Crassulacean acid metabolism (CAM) species. Current knowledge of CAM metabolism suggests that the enzyme phosphoenolpyruvate carboxylase kinase (PPCK) is circadian regulated at the transcriptional level, whereas phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (MDH), NADP-malic enzyme (NADP-ME), and pyruvate phosphate dikinase (PPDK) are posttranslationally controlled. As little transcriptomic data are available from obligate CAM plants, we created an expressed sequence tag database derived from different organs and developmental stages. Sequences were assembled, compared with sequences in the National Center for Biotechnology Information nonredundant database for identification of putative orthologs, and mapped using Kyoto Encyclopedia of Genes and Genomes Orthology and Gene Ontology. We identified genes involved in circadian regulation and CAM metabolism for transcriptomic analysis in plants grown in long days. We identified stable reference genes for quantitative polymerase chain reaction and found that OfiSAND, like its counterpart in Arabidopsis (Arabidopsis thaliana), and OfiTUB are generally appropriate standards for use in the quantification of gene expression in O. ficus-indica. Three kinds of expression profiles were found: transcripts of OfiPPCK oscillated with a 24-h periodicity; transcripts of the light-active OfiNADP-ME and OfiPPDK genes adapted to 12-h cycles, while transcript accumulation patterns of OfiPEPC and OfiMDH were arrhythmic. Expression of the circadian clock gene OfiTOC1, similar to Arabidopsis, oscillated with a 24-h periodicity, peaking at night. Expression of OfiCCA1 and OfiPRR9, unlike in Arabidopsis, adapted best to a 12-h rhythm, suggesting that circadian clock gene interactions differ from those of Arabidopsis. Our results indicate that the evolution of CAM metabolism could be the result of modified circadian regulation at both the transcriptional and posttranscriptional

  9. Mathematical modeling of light-mediated HPA axis activity and downstream implications on the entrainment of peripheral clock genes.

    PubMed

    Mavroudis, Panteleimon D; Corbett, Siobhan A; Calvano, Steven E; Androulakis, Ioannis P

    2014-10-15

    In this work we propose a semimechanistic model that describes the photic signal transduction to the hypothalamic-pituitary-adrenal (HPA) axis that ultimately regulates the synchronization of peripheral clock genes (PCGs). Our HPA axis model predicts that photic stimulation induces a type-1 phase response curve to cortisol's profile with increased cortisol sensitivity to light exposure in its rising phase, as well as the shortening of cortisol's period as constant light increases (Aschoff's first rule). Furthermore, our model provides insight into cortisol's phase and amplitude dependence on photoperiods and reveals that cortisol maintains highest amplitude variability when it is entrained by a balanced schedule of light and dark periods. Importantly, by incorporating the links between HPA axis and PCGs we were able to investigate how cortisol secretion impacts the entrainment of a population of peripheral cells and show that disrupted light schedules, leading to blunted cortisol secretion, fail to synchronize a population of PCGs which further signifies the loss of circadian rhythmicity in the periphery of the body. PMID:25073602

  10. Regulation of behavioral circadian rhythms and clock protein PER1 by the deubiquitinating enzyme USP2

    PubMed Central

    Yang, Yaoming; Duguay, David; Bédard, Nathalie; Rachalski, Adeline; Baquiran, Gerardo; Na, Chan Hyun; Fahrenkrug, Jan; Storch, Kai-Florian; Peng, Junmin; Wing, Simon S.; Cermakian, Nicolas

    2012-01-01

    Summary Endogenous 24-hour rhythms are generated by circadian clocks located in most tissues. The molecular clock mechanism is based on feedback loops involving clock genes and their protein products. Post-translational modifications, including ubiquitination, are important for regulating the clock feedback mechanism. Previous work has focused on the role of ubiquitin ligases in the clock mechanism. Here we show a role for the rhythmically-expressed deubiquitinating enzyme ubiquitin specific peptidase 2 (USP2) in clock function. Mice with a deletion of the Usp2 gene (Usp2 KO) display a longer free-running period of locomotor activity rhythms and altered responses of the clock to light. This was associated with altered expression of clock genes in synchronized Usp2 KO mouse embryonic fibroblasts and increased levels of clock protein PERIOD1 (PER1). USP2 can be coimmunoprecipitated with several clock proteins but directly interacts specifically with PER1 and deubiquitinates it. Interestingly, this deubiquitination does not alter PER1 stability. Taken together, our results identify USP2 as a new core component of the clock machinery and demonstrate a role for deubiquitination in the regulation of the circadian clock, both at the level of the core pacemaker and its response to external cues. PMID:23213472

  11. Timing of expression of the core clock gene Bmal1 influences its effects on aging and survival

    PubMed Central

    Yang, Guangrui; Chen, Lihong; Grant, Gregory R.; Paschos, Georgios; Song, Wen-Liang; Musiek, Erik S.; Lee, Vivian; McLoughlin, Sarah C.; Grosser, Tilo; Cotsarelis, George; FitzGerald, Garret A.

    2016-01-01

    The absence of Bmal1, a core clock gene, results in a loss of circadian rhythms, an acceleration of aging, and a shortened life span in mice. To address the importance of circadian rhythms in the aging process, we generated conditional Bmal1 knockout mice that lacked the BMAL1 protein during adult life and found that wild-type circadian variations in wheel-running activity, heart rate, and blood pressure were abolished. Ocular abnormalities and brain astrogliosis were conserved irrespective of the timing of Bmal1 deletion. However, life span, fertility, body weight, blood glucose levels, and age-dependent arthropathy - which are altered in standard Bmal1 knockout mice - remained unaltered, while atherosclerosis and hair growth improved, in the conditional adult-life Bmal1 knockout mice, despite abolition of clock function. Hepatic RNA-Seq revealed that expression of oscillatory genes was dampened in the adult-life Bmal1 knockout mice, while overall gene expression was largely unchanged. Thus, many phenotypes in conventional Bmal1 knockout mice, hitherto attributed to disruption of circadian rhythms, reflect the loss of properties of BMAL1 that are independent of its role in the clock. These findings prompt re-evaluation of the systemic consequences of disruption of the molecular clock. PMID:26843191

  12. The Arabidopsis SRR1 gene mediates phyB signaling and is required for normal circadian clock function

    PubMed Central

    Staiger, Dorothee; Allenbach, Laure; Salathia, Neeraj; Fiechter, Vincent; Davis, Seth J.; Millar, Andrew J.; Chory, Joanne; Fankhauser, Christian

    2003-01-01

    Plants possess several photoreceptors to sense the light environment. In Arabidopsis cryptochromes and phytochromes play roles in photomorphogenesis and in the light input pathways that synchronize the circadian clock with the external world. We have identified SRR1 (sensitivity to red light reduced), a gene that plays an important role in phytochrome B (phyB)-mediated light signaling. The recessive srr1 null allele and phyB mutants display a number of similar phenotypes indicating that SRR1 is required for normal phyB signaling. Genetic analysis suggests that SRR1 works both in the phyB pathway but also independently of phyB. srr1 mutants are affected in multiple outputs of the circadian clock in continuous light conditions, including leaf movement and expression of the clock components, CCA1 and TOC1. Clock-regulated gene expression is also impaired during day–night cycles and in constant darkness. The circadian phenotypes of srr1 mutants in all three conditions suggest that SRR1 activity is required for normal oscillator function. The SRR1 gene was identified and shown to code for a protein conserved in numerous eukaryotes including mammals and flies, implicating a conserved role for this protein in both the animal and plant kingdoms. PMID:12533513

  13. Synergistic induction of the clock protein PERIOD by insulin-like peptide and prothoracicotropic hormone in Rhodnius prolixus (Hemiptera): implications for convergence of hormone signaling pathways

    PubMed Central

    Vafopoulou, Xanthe; Steel, Colin G. H.

    2014-01-01

    We showed previously that release of the cerebral neurohormones, bombyxin (an insulin-like peptide, ILP) and prothoracicotropic hormone (PTTH) from the brain have strong circadian rhythms, driven by master clock cells in the brain. These neurohormone rhythms synchronize the photosensitive brain clock with the photosensitive peripheral clock in the cells of the prothoracic glands (PGs), in which both regulate steroidogenesis. Here, using immunohistochemistry and confocal laser scanning microscopy, we show these neurohormones likely act on clock cells in the brain and PGs by regulating expression of PERIOD (PER) protein. PER is severely reduced in the nuclei of all clock cells in continuous light, but on transfer of tissues to darkness in vitro, it is rapidly induced. A 4h pulse of either PTTH or ILPs to brain and PGs in vitro both rapidly and highly significantly induce PER in the nuclei of clock cells. Administration of both neurohormones together induces more PER than does either alone and even more than does transfer to darkness, at least in PG cells. These are clearly non-steroidogenic actions of these peptides. In the peripheral oscillators salivary gland (SG) and fat body cells, neither bombyxin nor PTTH nor darkness induced PER, but a combination of both bombyxin and PTTH induced PER. Thus, PTTH and ILPs exert synergistic actions on induction of PER in both clock cells and peripheral oscillators, implying their signaling pathways converge, but in different ways in different cell types. We infer clock cells are able to integrate light cycle information with internal signals from hormones. PMID:24600396

  14. Influence of beta-blockers on the myocardial mRNA expressions of circadian clock- and metabolism-related genes.

    PubMed

    Ushijima, Kentarou; Maekawa, Tomohiro; Ishikawa-Kobayashi, Eiko; Ando, Hitoshi; Shiga, Tsuyoshi; Fujimura, Akio

    2013-01-01

    Daily rhythms are regulated by a master clock-system in the suprachiasmatic nucleus and by a peripheral clock-system in each organ. Because norepinephrine is one of the timekeepers for the myocardial circadian clock that influences cardiac metabolism, it is speculated that a beta-blocker may affect the circadian clock and metabolism in heart tissue. In this study, thirty mg/kg/day of propranolol (a lipophilic beta-blocker) or atenolol (a hydrophilic beta-blocker) was given orally to Wistar rats for 4 weeks. The mRNA expressions of Bmal1 and E4BP4 in heart tissue were suppressed by the beta-blockers. However, the mRNA expressions of these clock genes in the suprachiasmatic nucleus were unchanged. Myocardial mRNA expressions of lactate dehydrogenase a and pyruvate dehydrogenase kinase 4 were also suppressed by the beta-blockers. In addition, ATP content in heart tissue was significantly elevated by the beta-blockers throughout 24 hours. The effects of propranolol and atenolol did not differ significantly. This study showed for the first time that a beta-blocker affects myocardial clock gene expression. Propranolol and atenolol increased ATP content in heart tissue throughout 24 hours. The influences of beta-blockers may be negligible on the SCN, and may be independent of lipid solubility on heart tissue. It is well known that these drugs exert a protective effect against myocardial ischemia, which may be mediated by an increase in the preservation of myocardial ATP. PMID:23394803

  15. Explaining the sawtooth: latitudinal periodicity in a circadian gene correlates with shifts in generation number.

    PubMed

    Levy, R C; Kozak, G M; Wadsworth, C B; Coates, B S; Dopman, E B

    2015-01-01

    Many temperate insects take advantage of longer growing seasons at lower latitudes by increasing their generation number or voltinism. In some insects, development time abruptly decreases when additional generations are fit into the season. Consequently, latitudinal 'sawtooth' clines associated with shifts in voltinism are seen for phenotypes correlated with development time, like body size. However, latitudinal variation in voltinism has not been linked to genetic variation at specific loci. Here, we show a pattern in allele frequency among voltinism ecotypes of the European corn borer moth (Ostrinia nubilalis) that is reminiscent of a sawtooth cline. We characterized 145 autosomal and sex-linked SNPs and found that period, a circadian gene that is genetically linked to a major QTL determining variation in post-diapause development time, shows cyclical variation between voltinism ecotypes. Allele frequencies at an unlinked circadian clock gene cryptochrome1 were correlated with period. These results suggest that selection on development time to 'fit' complete life cycles into a latitudinally varying growing season produces oscillations in alleles associated with voltinism, primarily through changes at loci underlying the duration of transitions between diapause and other life history phases. Correlations among clock loci suggest possible coupling between the circadian clock and the circannual rhythms for synchronizing seasonal life history. We anticipate that latitudinal oscillations in allele frequency will represent signatures of adaptation to seasonal environments in other insects and may be critical to understanding the ecological and evolutionary consequences of variable environments, including response to global climate change. PMID:25430782

  16. Photoperiodic Modulation of Circadian Clock and Reproductive Axis Gene Expression in the Pre-Pubertal European Sea Bass Brain

    PubMed Central

    Martins, Rute S. T.; Gomez, Ana; Zanuy, Silvia; Carrillo, Manuel; Canário, Adelino V. M.

    2015-01-01

    The acquisition of reproductive competence requires the activation of the brain-pituitary-gonad (BPG) axis, which in most vertebrates, including fishes, is initiated by changes in photoperiod. In the European sea bass long-term exposure to continuous light (LL) alters the rhythm of reproductive hormones, delays spermatogenesis and reduces the incidence of precocious males. In contrast, an early shift from long to short photoperiod (AP) accelerates spermatogenesis. However, how photoperiod affects key genes in the brain to trigger the onset of puberty is still largely unknown. Here, we investigated if the integration of the light stimulus by clock proteins is sufficient to activate key genes that trigger the BPG axis in the European sea bass. We found that the clock genes clock, npas2, bmal1 and the BPG genes gnrh, kiss and kissr share conserved transcription factor frameworks in their promoters, suggesting co-regulation. Other gene promoters of the BGP axis were also predicted to be co-regulated by the same frameworks. Co-regulation was confirmed through gene expression analysis of brains from males exposed to LL or AP photoperiod compared to natural conditions: LL fish had suppressed gnrh1, kiss2, galr1b and esr1, while AP fish had stimulated npas2, gnrh1, gnrh2, kiss2, kiss1rb and galr1b compared to NP. It is concluded that fish exposed to different photoperiods present significant expression differences in some clock and reproductive axis related genes well before the first detectable endocrine and morphological responses of the BPG axis. PMID:26641263

  17. Circadian molecular clock in lung pathophysiology.

    PubMed

    Sundar, Isaac K; Yao, Hongwei; Sellix, Michael T; Rahman, Irfan

    2015-11-15

    Disrupted daily or circadian rhythms of lung function and inflammatory responses are common features of chronic airway diseases. At the molecular level these circadian rhythms depend on the activity of an autoregulatory feedback loop oscillator of clock gene transcription factors, including the BMAL1:CLOCK activator complex and the repressors PERIOD and CRYPTOCHROME. The key nuclear receptors and transcription factors REV-ERBα and RORα regulate Bmal1 expression and provide stability to the oscillator. Circadian clock dysfunction is implicated in both immune and inflammatory responses to environmental, inflammatory, and infectious agents. Molecular clock function is altered by exposomes, tobacco smoke, lipopolysaccharide, hyperoxia, allergens, bleomycin, as well as bacterial and viral infections. The deacetylase Sirtuin 1 (SIRT1) regulates the timing of the clock through acetylation of BMAL1 and PER2 and controls the clock-dependent functions, which can also be affected by environmental stressors. Environmental agents and redox modulation may alter the levels of REV-ERBα and RORα in lung tissue in association with a heightened DNA damage response, cellular senescence, and inflammation. A reciprocal relationship exists between the molecular clock and immune/inflammatory responses in the lungs. Molecular clock function in lung cells may be used as a biomarker of disease severity and exacerbations or for assessing the efficacy of chronotherapy for disease management. Here, we provide a comprehensive overview of clock-controlled cellular and molecular functions in the lungs and highlight the repercussions of clock disruption on the pathophysiology of chronic airway diseases and their exacerbations. Furthermore, we highlight the potential for the molecular clock as a novel chronopharmacological target for the management of lung pathophysiology. PMID:26361874

  18. A Compact Model for the Complex Plant Circadian Clock

    PubMed Central

    De Caluwé, Joëlle; Xiao, Qiying; Hermans, Christian; Verbruggen, Nathalie; Leloup, Jean-Christophe; Gonze, Didier

    2016-01-01

    The circadian clock is an endogenous timekeeper that allows organisms to anticipate and adapt to the daily variations of their environment. The plant clock is an intricate network of interlocked feedback loops, in which transcription factors regulate each other to generate oscillations with expression peaks at specific times of the day. Over the last decade, mathematical modeling approaches have been used to understand the inner workings of the clock in the model plant Arabidopsis thaliana. Those efforts have produced a number of models of ever increasing complexity. Here, we present an alternative model that combines a low number of equations and parameters, similar to the very earliest models, with the complex network structure found in more recent ones. This simple model describes the temporal evolution of the abundance of eight clock gene mRNA/protein and captures key features of the clock on a qualitative level, namely the entrained and free-running behaviors of the wild type clock, as well as the defects found in knockout mutants (such as altered free-running periods, lack of entrainment, or changes in the expression of other clock genes). Additionally, our model produces complex responses to various light cues, such as extreme photoperiods and non-24 h environmental cycles, and can describe the control of hypocotyl growth by the clock. Our model constitutes a useful tool to probe dynamical properties of the core clock as well as clock-dependent processes. PMID:26904049

  19. Clock genes explain large proportion of phenotypic variance in systolic blood pressure and this control is not modified by environmental temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND: Diurnal variation in blood pressure (BP) is regulated, in part, by an endogenous circadian clock; however, few human studies have identified associations between clock genes and BP. Accounting for environmental temperature may be necessary to correct for seasonal bias. METHODS: We examin...

  20. Clock genes explain large proportion of phenotypic variance in systolic blood pressure and this control is not modified by environmental temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Diurnal variation in blood pressure (BP) is regulated, in part, by an endogenous circadian clock, however few human studies have identified associations between clock genes and BP. Accounting for environmental temperature may be necessary to correct for seasonal bias. Methods: We examine...

  1. The aging biological clock in Neurospora crassa

    PubMed Central

    Case, Mary E; Griffith, James; Dong, Wubei; Tigner, Ira L; Gaines, Kimberly; Jiang, James C; Jazwinski, S Michal; Arnold, Jonathan

    2014-01-01

    The biological clock affects aging through ras-1 (bd) and lag-1, and these two longevity genes together affect a clock phenotype and the clock oscillator in Neurospora crassa. Using an automated cell-counting technique for measuring conidial longevity, we show that the clock-associated genes lag-1 and ras-1 (bd) are true chronological longevity genes. For example, wild type (WT) has an estimated median life span of 24 days, while the double mutant lag-1, ras-1 (bd) has an estimated median life span of 120 days for macroconidia. We establish the biochemical function of lag-1 by complementing LAG1 and LAC1 in Saccharomyces cerevisiae with lag-1 in N. crassa. Longevity genes can affect the clock as well in that, the double mutant lag-1, ras-1 (bd) can stop the circadian rhythm in asexual reproduction (i.e., banding in race tubes) and lengthen the period of the frequency oscillator to 41 h. In contrast to the ras-1 (bd), lag-1 effects on chronological longevity, we find that this double mutant undergoes replicative senescence (i.e., the loss of replication function with time), unlike WT or the single mutants, lag-1 and ras-1 (bd). These results support the hypothesis that sphingolipid metabolism links aging and the biological clock through a common stress response PMID:25535564

  2. Circadian rhythms of clock gene expression in Nile tilapia (Oreochromis niloticus) central and peripheral tissues: influence of different lighting and feeding conditions.

    PubMed

    Costa, Leandro S; Serrano, Ignacio; Sánchez-Vázquez, Francisco J; López-Olmeda, Jose F

    2016-08-01

    The present research aimed to investigate the existence of clock gene expression rhythms in tilapia, their endogenous origin, and how light and feeding cycles synchronize these rhythms. In the first experiment, two groups of fish were kept under an LD cycle and fed at two different time points: in the middle of the light (ML) or in the middle of the dark (MD) phase. In the second experiment, fish fed at ML was fasted and kept under constant lighting (LL) conditions for 1 day. In both experiments, the samples from central (optic tectum and hypothalamus) and peripheral (liver) tissues were collected every 3 h throughout a 24 h cycle. The expression levels of clock genes bmal1a, clock1, per1b, cry2a, and cry5 were analyzed by quantitative PCR. All the clock genes analyzed in brain regions showed daily rhythms: clock1, bmal1a, and cry2a showed the acrophase approximately at the end of the light phase (ZT 8:43-11:22 h), whereas per1b and cry5 did so between the end of the dark phase and the beginning of the light phase, respectively (ZT 21:16-4:00 h). These rhythms persisted under constant conditions. No effect of the feeding time was observed in the brain. In the liver, however, the rhythms of clock1 and cry5 were influenced by feeding, and a shift was observed in the MD fish group (ZT 3:58 h for clock1 and 11:20 h for cry5). This study provides the first insights into the molecular clock of tilapia, a very important fish species for aquaculture. It also reveals the endogenous origin of clock gene rhythms and the ability of feeding time to shift the phase in some clock genes in the peripheral, but not the central, oscillator. PMID:27085855

  3. Synchronization of Cellular Clocks in the Suprachiasmatic Nucleus

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Shun; Isejima, Hiromi; Matsuo, Takuya; Okura, Ryusuke; Yagita, Kazuhiro; Kobayashi, Masaki; Okamura, Hitoshi

    2003-11-01

    Individual cellular clocks in the suprachiasmatic nucleus (SCN), the circadian center, are integrated into a stable and robust pacemaker with a period length of about 24 hours. We used real-time analysis of gene expression to show synchronized rhythms of clock gene transcription across hundreds of neurons within the mammalian SCN in organotypic slice culture. Differentially phased neuronal clocks are topographically arranged across the SCN. A protein synthesis inhibitor set all cell clocks to the same initial phase and, after withdrawal, intrinsic interactions among cell clocks reestablished the stable program of gene expression across the assemblage. Na+-dependent action potentials contributed to establishing cellular synchrony and maintaining spontaneous oscillation across the SCN.

  4. Rapid attenuation of circadian clock gene oscillations in the rat heart following ischemia-reperfusion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The intracellular circadian clock consists of a series of transcriptional modulators that together allow the cell to perceive the time of day. Circadian clocks have been identified within various components of the cardiovascular system (e.g., cardiomyocytes, vascular smooth muscle cells) and possess...

  5. Glucocorticoids affect 24 h clock genes expression in human adipose tissue explant cultures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To examine firstly whether CLOCK exhibits a circadian expression in human visceral (V) and subcutaneous (S) adipose tissue (AT) in vitro as compared with BMAL1 and PER2, and secondly to investigate the possible effect of the glucocorticoid analogue dexamethasone (DEX) on positive and negative clock ...

  6. The effect of white light on normal and malignant murine melanocytes: A link between opsins, clock genes, and melanogenesis.

    PubMed

    de Assis, L V M; Moraes, M N; da Silveira Cruz-Machado, S; Castrucci, A M L

    2016-06-01

    The skin possesses a photosensitive system comprised of opsins whose function is not fully understood, and clock genes which exert an important regulatory role in skin biology. Here, we evaluated the presence of opsins in normal (Melan-a cells) and malignant (B16-F10 cells) murine melanocytes. Both cell lines express Opn2, Opn4--for the first time reported in these cell types--as well as S-opsin. OPN4 protein was found in a small area capping the cell nuclei of B16-F10 cells kept in constant dark (DD); twenty-four hours after the white light pulse (WLP), OPN4 was found in the cell membrane. Despite the fact that B16-F10 cells expressed less Opn2 and Opn4 than Melan-a cells, our data indicate that the malignant melanocytes exhibited increased photoresponsiveness. The clock gene machinery is also severely downregulated in B16-F10 cells as compared to Melan-a cells. Per1, Per2, and Bmal1 expression increased in B16-F10 cells in response to WLP. Although no response in clock gene expression to WLP was observed in Melan-a cells, gene correlational data suggest a minor effect of WLP. In contrast to opsins and clock genes, melanogenesis is significantly upregulated in malignant melanocytes in comparison to Melan-a cells. Tyrosinase expression increased after WLP only in B16-F10 cells; however no increase in melanin content after WLP was seen in either cell line. Our findings may prove useful in the treatment and the development of new pharmacological approaches of depigmentation diseases and skin cancer. PMID:26947915

  7. Genetic analysis of ectopic circadian clock induction in Drosophila.

    PubMed

    Kilman, Valerie L; Allada, Ravi

    2009-10-01

    Cell-autonomous feedback loops underlie the molecular oscillations that define circadian clocks. In Drosophila the transcription factor Clk activates multiple clock components of feedback loops many of which feed back and regulate Clk expression or activity. Previously the authors evoked similar molecular oscillations in putatively naïve neurons in Drosophila by ectopic expression of a single gene, Clk, suggesting a master regulator function. Using molecular oscillations of the core clock component PERIOD (PER), the authors observed dramatic and widespread molecular oscillations throughout the brain in flies expressing ectopic Clk. Consistent with the master regulator hypothesis, they found that Clk is uniquely capable of inducing ectopic clocks as ectopic induction of other clock components fails to induce circadian rhythms. Clk also induces oscillations even when expression is adult restricted, suggesting that ectopic clocks can even be induced in differentiated cells. However, if transgene expression is discontinued, PER expression disappears, indicating that Clk must be continually active to sustain ectopic clock function. In some cases Clk-mediated PER induction was observed without apparent synchronous cycling, perhaps due to desynchronization of rhythms between clocks or truly cell autonomous arrhythmic PER expression, indicating that additional factors may be necessary for coherent rhythms in cells ectopically expressing Clk. To determine minimal requirements for circadian clock induction by Clk, the authors determined the genetic requirements of ectopic clocks. No ectopic clocks are induced in mutants of Clk's heterodimeric partner cyc. In addition, noncycling PER is observed when ectopic Clk is induced in a cryb mutant background. While other factors may contribute, these results indicate that persistent Clock induction is uniquely capable of broadly inducing ectopic rhythms even in adults, consistent with a special role at the top of a clock gene

  8. Development and morphology of the clock-gene-expressing lateral neurons of Drosophila melanogaster.

    PubMed

    Helfrich-Förster, Charlotte; Shafer, Orie T; Wülbeck, Corinna; Grieshaber, Eva; Rieger, Dirk; Taghert, Paul

    2007-01-01

    The clock-gene-expressing lateral neurons are essential for the locomotor activity rhythm of Drosophila melanogaster. Traditionally, these neurons are divided into three groups: the dorsal lateral neurons (LN(d)), the large ventral lateral neurons (l-LN(v)), and the small ventral lateral neurons (s-LN(v)), whereby the latter group consists of four neurons that express the neuropeptide pigment-dispersing factor (PDF) and a fifth PDF-negative neuron. So far, only the l-LN(v) and the PDF-positive s-LN(v) have been shown to project into the accessory medulla, a small neuropil that contains the circadian pacemaker center in several insects. We show here that the other lateral neurons also arborize in the accessory medulla, predominantly forming postsynaptic sites. Both the l-LN(v) and LN(d) are anatomically well suited to connect the accessory medullae. Whereas the l-LN(v) may receive ipsilateral photic input from the Hofbauer-Buchner eyelet, the LN(d) invade mainly the contralateral accessory medulla and thus may receive photic input from the contralateral side. Both the LN(d) and the l-LN(v) differentiate during midmetamorphosis. They do so in close proximity to one another and the fifth PDF-negative s-LN(v), suggesting that these cell groups may derive from common precursors. PMID:17099895

  9. Melanopsin and clock genes: regulation by light and endothelin in the zebrafish ZEM-2S cell line.

    PubMed

    Farhat, Fernanda Pizão; Martins, Cassia Bulhōes; De Lima, Leonardo Henrique Ribeiro Graciani; Isoldi, Mauro Cesar; Castrucci, Ana Maria De Lauro

    2009-08-01

    It is well known that clocks are present in brain regions other than the suprachiasmatic nucleus and in many peripheral tissues. In the teleost, Danio rerio, peripheral oscillators can be directly synchronized by light. Danio rerio ZEM-2S embryonic cells respond to light with differential growth: cells kept in constant light exhibited a strong inhibition of proliferation, whereas in cells kept in light:dark (LD) cycles (14L:10D and 10L:14D) or in constant darkness (DD), the doubling times were not statistically different. We demonstrated by RT-PCR followed by PCR that ZEM-2S cells express two melanopsins, Opn4x and Opn4m, and the six Cry genes. The presence of the protein OPN4x was demonstrated by immunocytochemistry. The pattern of temporal expression of the genes Opn4x, Per1, Cry1b, and Clock was studied in ZEM-2S cells kept for five days in 12L:12D or DD. In 12L:12D, the clock genes Per 1 and Cry1b exhibited robust circadian expression, while Opn4x and Clock expression seemed to vary in an ultradian pattern. Both Per1 and Cry1b genes had higher expression during the L phase; Clock gene had an increase in expression coincident with the D phase, and during the subjective night. In DD, the temporal variation of Per1 and Cry1b genes was greatly attenuated but not extinguished, and the higher expressions were shifted to the transition times between subjective day and night, demonstrating that Per and Cry1b were synchronized by the LD cycle. Clock and Opn4x kept the ultradian oscillation, but the rhythm was not statistically significant. As endothelins (ET) have been reported to be a potent stimulator of Per genes in rodents, we investigated the effect of endothelin on ZEM-2S cells, which express ETA receptors. Cells were kept in 12D:12L for five days, and then treated with 10(-11) to 10(-8)M ET-1 for 24 h. ET-1 exhibited a biphasic effect on Opn4x expression. At 10(-11)M, the hormone exerted a highly significant stimulation of Opn4x expression during the L phase and

  10. Periodic transition on an axial compressor stator: Incidence and clocking effects. Part 2: Transition onset predictions

    SciTech Connect

    Solomon, W.J.; Walker, G.J.; Hughes, J.D.

    1999-07-01

    Transition onset observations from a 1.5-stage axial compressor outlet stator presented in Part 1 of this paper are compared with the predictions of conventional transition correlations applied in a quasi-steady manner. The viscous/inviscid interaction code MISES is used to predict the blade surface pressure distributions, and boundary layer development. The temporal variation in transition onset is then predicted using ensemble-averaged free-stream turbulence data from the compressor measurements. This simple procedure captures most significant features of the complex transition process on the compressor, and is clearly superior to fixed transition models based on long-term average free-stream turbulence levels. Parallel computations for both natural and bypass transition modes indicate that the natural transition mode tends to dominate on the compressor. This is at variance with turbine airfoil experience, where bypass transition is clearly more important. Comparison of prediction and experiment highlights the significance of leading edge potential flow interactions in promoting periodic wake-induced transition. Viscous/inviscid interactions in the neighborhood of transition can also have an important influence on boundary layer stability and separation phenomena.

  11. Clock genes, melanopsins, melatonin, and dopamine key enzymes and their modulation by light and glutamate in chicken embryonic retinal cells.

    PubMed

    Lima, Leonardo Henrique Ribeiro Graciani de; Santos, Kátia Pereira dos; Lauro Castrucci, Ana Maria de

    2011-03-01

    The avian circadian system is composed of the retina, the mammalian homolog region of the suprachiasmatic nucleus (SNC), and the pineal gland. The retina, itself, displays many rhythmic physiological events, such as movements of photoreceptor cells, opsin expression, retinal reisomerization, and melatonin and dopamine production and secretion. Altogether, these rhythmic events are coordinated to predict environmental changes in light conditions during the day, optimizing retina function. The authors investigated the expression pattern of the melanopsin genes Opn4x and Opn4m, the clock genes Clock and Per2, and the genes for the key enzymes N-Acetyltransferase and Tyrosine Hidroxylase in chicken embryo dispersed retinal cells. Primary cultures of chicken retina from 8-day-old embryos were kept in constant dark (DD), in 12-h light/12-h dark (12L:12D), in 12L:12D followed by DD, or in DD in the absence or presence of 100 µM glutamate for 12 h. Total RNA was extracted throughout a 24-h span, every 3 h starting at zeitgeber time 0 (ZT0) of the 6th day, and submitted to reverse transcriptase-polymerase chain reaction (RT-PCR) followed by quantitative PCR (qPCR) for mRNA quantification. The data showed no rhythmic pattern of transcription for any gene in cells kept in DD. However under a light-dark cycle, Clock, Per2, Opn4m, N-Acetyltransferase, and Tyrosine Hydroxylase exhibited rhythmic patterns of transcription. In DD, 100 µM glutamate was able to induce rhythmic expression of Clock, strongly inhibited the expression of Tyrosine Hydroxylase, and, only at some ZTs, of Opn4x and Opn4m. The neurotransmitter had no effect on Per2 and N-Acetyltransferase transcription. The authors confirmed the expression of the protein OPN4x by immunocytochemistry. These results suggest that chicken embryonic retinal cells contain a functional circadian clock, whose synchronization requires light-dark cycle or glutamate stimuli. PMID:21231870

  12. Adenosinergic regulation of striatal clock gene expression and ethanol intake during constant light.

    PubMed

    Ruby, Christina L; Vadnie, Chelsea A; Hinton, David J; Abulseoud, Osama A; Walker, Denise L; O'Connor, Katheryn M; Noterman, Maria F; Choi, Doo-Sup

    2014-09-01

    Circadian rhythm and sleep disruptions occur frequently in individuals with alcohol use disorders (AUD) and present significant barriers to treatment. Recently, a variant of adenosine transporter, equilibrative nucleoside transporter 1 (ENT1), was associated with the co-occurrence of sleep problems and AUD. We have previously shown that mice lacking ENT1 (ENT1 KO) have reduced adenosine levels in the striatum and drink more alcohol compared with wild types (WT). However, it is unknown whether ENT1 deletion disrupts circadian rhythms, which may contribute to alcohol preference in ENT1 KO mice. Here we used these mice to determine whether endogenous adenosine regulates circadian genetic and behavioral rhythms and influences alcohol intake during chronodisruption. We examined circadian locomotor activity in ENT1 KO vs WT littermates and found that ENT1 KO mice were both active earlier and hyperactive compared with WT mice at night. We used real-time PCR and immunohistochemistry to estimate striatal clock gene levels and found that PER2 expression in the striatum was blunted by ENT1 deletion or A2A receptor (A2AR) antagonism. Next, we exposed ENT1 KO and WT mice to constant light (LL) and found further elevation in ethanol intake in ENT1 KO, but not in WT mice, supporting the notion that circadian dysfunction may contribute to increased alcohol intake in ENT1 KO mice. Finally, we showed that A2AR agonist administration normalized PER1 and PER2 expression and circadian locomotor activity in ENT1 KO mice. Together, our results demonstrate that adenosine signaling regulates cellular and behavioral circadian timing and influences alcohol intake during chronodisruption. PMID:24755889

  13. Adenosinergic Regulation of Striatal Clock Gene Expression and Ethanol Intake During Constant Light

    PubMed Central

    Ruby, Christina L; Vadnie, Chelsea A; Hinton, David J; Abulseoud, Osama A; Walker, Denise L; O'Connor, Katheryn M; Noterman, Maria F; Choi, Doo-Sup

    2014-01-01

    Circadian rhythm and sleep disruptions occur frequently in individuals with alcohol use disorders (AUD) and present significant barriers to treatment. Recently, a variant of adenosine transporter, equilibrative nucleoside transporter 1 (ENT1), was associated with the co-occurrence of sleep problems and AUD. We have previously shown that mice lacking ENT1 (ENT1 KO) have reduced adenosine levels in the striatum and drink more alcohol compared with wild types (WT). However, it is unknown whether ENT1 deletion disrupts circadian rhythms, which may contribute to alcohol preference in ENT1 KO mice. Here we used these mice to determine whether endogenous adenosine regulates circadian genetic and behavioral rhythms and influences alcohol intake during chronodisruption. We examined circadian locomotor activity in ENT1 KO vs WT littermates and found that ENT1 KO mice were both active earlier and hyperactive compared with WT mice at night. We used real-time PCR and immunohistochemistry to estimate striatal clock gene levels and found that PER2 expression in the striatum was blunted by ENT1 deletion or A2A receptor (A2AR) antagonism. Next, we exposed ENT1 KO and WT mice to constant light (LL) and found further elevation in ethanol intake in ENT1 KO, but not in WT mice, supporting the notion that circadian dysfunction may contribute to increased alcohol intake in ENT1 KO mice. Finally, we showed that A2AR agonist administration normalized PER1 and PER2 expression and circadian locomotor activity in ENT1 KO mice. Together, our results demonstrate that adenosine signaling regulates cellular and behavioral circadian timing and influences alcohol intake during chronodisruption. PMID:24755889

  14. Caenorhabditis elegans opens up new insights into circadian clock mechanisms.

    PubMed

    Hasegawa, Kenji; Saigusa, Tetsu; Tamai, Yoichi

    2005-01-01

    The roundworm, Caenorhabditis elegans, is known to carry homologues of clock genes such as per (=period) and tim (=timeless), which constitute the core of the circadian clock in Drosophila and mammals: lin-42 and tim-1. Analyses using WormBase (C. elegans gene database) have identified with relatively high identity analogous of the clock genes recognized in Drosophila and mammals, with the notable exception of cry (=cryptochrome), which is lacking in C. elegans. All of these C. elegans cognates of the clock genes appear to belong to members of the PAS-superfamily and to participate in development or responsiveness to the environment but apparently are not involved in the C. elegans circadian clock. Nevertheless, C. elegans exhibits convincing circadian rhythms in locomotor behavior in the adult stage and in resistance to hyperosmotic stress in starved larvae (L1) after hatching, indicating that it has a circadian clock with a core design entirely different from that of Drosophila and mammals. Here two possibilities are considered. First, the core of the C. elegans circadian clock includes transcriptional/translational feedback loops between genes and their protein products that are entirely different from those of Drosophila and mammals. Second, a more basic principle such as homeostasis governs the circadian cellular physiology, and was established primarily to minimize the accumulation of DNA damage in response to an environment cycling at 24 h intervals. PMID:15865318

  15. Effects of Photoperiod Extension on Clock Gene and Neuropeptide RNA Expression in the SCN of the Soay Sheep

    PubMed Central

    Dardente, Hugues; Wyse, Cathy A.; Lincoln, Gerald A.; Wagner, Gabriela C.; Hazlerigg, David G.

    2016-01-01

    In mammals, changing daylength (photoperiod) is the main synchronizer of seasonal functions. The photoperiodic information is transmitted through the retino-hypothalamic tract to the suprachiasmatic nuclei (SCN), site of the master circadian clock. To investigate effects of day length change on the sheep SCN, we used in-situ hybridization to assess the daily temporal organization of expression of circadian clock genes (Per1, Per2, Bmal1 and Fbxl21) and neuropeptides (Vip, Grp and Avp) in animals acclimated to a short photoperiod (SP; 8h of light) and at 3 or 15 days following transfer to a long photoperiod (LP3, LP15, respectively; 16h of light), achieved by an acute 8-h delay of lights off. We found that waveforms of SCN gene expression conformed to those previously seen in LP acclimated animals within 3 days of transfer to LP. Mean levels of expression for Per1-2 and Fbxl21 were nearly 2-fold higher in the LP15 than in the SP group. The expression of Vip was arrhythmic and unaffected by photoperiod, while, in contrast to rodents, Grp expression was not detectable within the sheep SCN. Expression of the circadian output gene Avp cycled robustly in all photoperiod groups with no detectable change in phasing. Overall these data suggest that synchronizing effects of light on SCN circadian organisation proceed similarly in ungulates and in rodents, despite differences in neuropeptide gene expression. PMID:27458725

  16. Protein Phosphatase 1 (PP1) Is a Post-Translational Regulator of the Mammalian Circadian Clock

    PubMed Central

    Schmutz, Isabelle; Wendt, Sabrina; Schnell, Anna; Kramer, Achim; Mansuy, Isabelle M.; Albrecht, Urs

    2011-01-01

    Circadian clocks coordinate the timing of important biological processes. Interconnected transcriptional and post-translational feedback loops based on a set of clock genes generate and maintain these rhythms with a period of about 24 hours. Many clock proteins undergo circadian cycles of post-translational modifications. Among these modifications, protein phosphorylation plays an important role in regulating activity, stability and intracellular localization of clock components. Several protein kinases were characterized as regulators of the circadian clock. However, the function of protein phosphatases, which balance phosphorylation events, in the mammalian clock mechanism is less well understood. Here, we identify protein phosphatase 1 (PP1) as regulator of period and light-induced resetting of the mammalian circadian clock. Down-regulation of PP1 activity in cells by RNA interference and in vivo by expression of a specific inhibitor in the brain of mice tended to lengthen circadian period. Moreover, reduction of PP1 activity in the brain altered light-mediated clock resetting behavior in mice, enhancing the phase shifts in either direction. At the molecular level, diminished PP1 activity increased nuclear accumulation of the clock component PER2 in neurons. Hence, PP1, may reduce PER2 phosphorylation thereby influencing nuclear localization of this protein. This may at least partially influence period and phase shifting properties of the mammalian circadian clock. PMID:21712997

  17. The association of circadian clock candidate genes to increased adiposity in the TIGER study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Obesity is a highly prevalent disease that has become a major health crisis in the United States. A number of studies have suggested a link between the altered sleep/wake patterns associated with our "24 hour" lifestyle and obesity. We hypothesize that disruption of the circadian clock intrinsic t...

  18. Human Diurnal Preference and Circadian Rhythmicity are Not Associated with the CLOCK 3111C/T Gene Polymorphism

    PubMed Central

    Chang, Anne-Marie; Buch, Alison M.; Bradstreet, Dayna S.; Klements, David J.; Duffy, Jeanne F.

    2013-01-01

    Genetic association studies of the CLOCK 3111C/T polymorphism and diurnal preference have yielded conflicting results since the first report that the 3111C allele was associated with eveningness. The goal of the present study was to investigate the association of this polymorphism with diurnal preference and circadian physiology in a group of 179 individuals, by comparing the frequency of the 3111C allele to diurnal preference, habitual sleep timing, circadian phase markers, and circadian period. We did not find a significant association between this allele and morningness/eveningness or any circadian marker. PMID:21628555

  19. Entrainment of the mouse circadian clock by sub-acute physical and psychological stress.

    PubMed

    Tahara, Yu; Shiraishi, Takuya; Kikuchi, Yosuke; Haraguchi, Atsushi; Kuriki, Daisuke; Sasaki, Hiroyuki; Motohashi, Hiroaki; Sakai, Tomoko; Shibata, Shigenobu

    2015-01-01

    The effects of acute stress on the peripheral circadian system are not well understood in vivo. Here, we show that sub-acute stress caused by restraint or social defeat potently altered clock gene expression in the peripheral tissues of mice. In these peripheral tissues, as well as the hippocampus and cortex, stressful stimuli induced time-of-day-dependent phase-advances or -delays in rhythmic clock gene expression patterns; however, such changes were not observed in the suprachiasmatic nucleus, i.e. the central circadian clock. Moreover, several days of stress exposure at the beginning of the light period abolished circadian oscillations and caused internal desynchronisation of peripheral clocks. Stress-induced changes in circadian rhythmicity showed habituation and disappeared with long-term exposure to repeated stress. These findings suggest that sub-acute physical/psychological stress potently entrains peripheral clocks and causes transient dysregulation of circadian clocks in vivo. PMID:26073568

  20. Machine learning helps identify CHRONO as a circadian clock component.

    PubMed

    Anafi, Ron C; Lee, Yool; Sato, Trey K; Venkataraman, Anand; Ramanathan, Chidambaram; Kavakli, Ibrahim H; Hughes, Michael E; Baggs, Julie E; Growe, Jacqueline; Liu, Andrew C; Kim, Junhyong; Hogenesch, John B

    2014-04-01

    Over the last decades, researchers have characterized a set of "clock genes" that drive daily rhythms in physiology and behavior. This arduous work has yielded results with far-reaching consequences in metabolic, psychiatric, and neoplastic disorders. Recent attempts to expand our understanding of circadian regulation have moved beyond the mutagenesis screens that identified the first clock components, employing higher throughput genomic and proteomic techniques. In order to further accelerate clock gene discovery, we utilized a computer-assisted approach to identify and prioritize candidate clock components. We used a simple form of probabilistic machine learning to integrate biologically relevant, genome-scale data and ranked genes on their similarity to known clock components. We then used a secondary experimental screen to characterize the top candidates. We found that several physically interact with known clock components in a mammalian two-hybrid screen and modulate in vitro cellular rhythms in an immortalized mouse fibroblast line (NIH 3T3). One candidate, Gene Model 129, interacts with BMAL1 and functionally represses the key driver of molecular rhythms, the BMAL1/CLOCK transcriptional complex. Given these results, we have renamed the gene CHRONO (computationally highlighted repressor of the network oscillator). Bi-molecular fluorescence complementation and co-immunoprecipitation demonstrate that CHRONO represses by abrogating the binding of BMAL1 to its transcriptional co-activator CBP. Most importantly, CHRONO knockout mice display a prolonged free-running circadian period similar to, or more drastic than, six other clock components. We conclude that CHRONO is a functional clock component providing a new layer of control on circadian molecular dynamics. PMID:24737000

  1. A tunable artificial circadian clock in clock-defective mice

    PubMed Central

    D'Alessandro, Matthew; Beesley, Stephen; Kim, Jae Kyoung; Chen, Rongmin; Abich, Estela; Cheng, Wayne; Yi, Paul; Takahashi, Joseph S.; Lee, Choogon

    2015-01-01

    Self-sustaining oscillations are essential for diverse physiological functions such as the cell cycle, insulin secretion and circadian rhythms. Synthetic oscillators using biochemical feedback circuits have been generated in cell culture. These synthetic systems provide important insight into design principles for biological oscillators, but have limited similarity to physiological pathways. Here we report the generation of an artificial, mammalian circadian clock in vivo, capable of generating robust, tunable circadian rhythms. In mice deficient in Per1 and Per2 genes (thus lacking circadian rhythms), we artificially generate PER2 rhythms and restore circadian sleep/wake cycles with an inducible Per2 transgene. Our artificial clock is tunable as the period and phase of the rhythms can be modulated predictably. This feature, and other design principles of our work, might enhance the study and treatment of circadian dysfunction and broader aspects of physiology involving biological oscillators. PMID:26617050

  2. Redox rhythm reinforces the circadian clock to gate immune response

    PubMed Central

    Zhou, Mian; Wang, Wei; Karapetyan, Sargis; Mwimba, Musoki; Marqués, Jorge; Buchler, Nicolas E.; Dong, Xinnian

    2015-01-01

    Recent studies have shown that in addition to the transcriptional circadian clock, many organisms, including Arabidopsis, have a circadian redox rhythm driven by the organism’s metabolic activities1–3. It has been hypothesized that the redox rhythm is linked to the circadian clock, but the mechanism and the biological significance of this link have only begun to be investigated4–7. Here we report that the master immune regulator NPR1 (non-expressor of pathogenesis-related gene 1) of Arabidopsis is a sensor of the plant’s redox state and regulates transcription of core circadian clock genes even in the absence of pathogen challenge. Surprisingly, acute perturbation in the redox status triggered by the immune signal salicylic acid (SA) does not compromise the circadian clock but rather leads to its reinforcement. Mathematical modelling and subsequent experiments show that NPR1 reinforces the circadian clock without changing the period by regulating both the morning and the evening clock genes. This balanced network architecture helps plants gate their immune responses towards the morning and minimize costs on growth at night. Our study demonstrates how a sensitive redox rhythm interacts with a robust circadian clock to ensure proper responsiveness to environmental stimuli without compromising fitness of the organism. PMID:26098366

  3. Clock-controlled output gene Dbp is a regulator of Arnt/Hif-1β gene expression in pancreatic islet β-cells

    SciTech Connect

    Nakabayashi, Hiroko; Ohta, Yasuharu Yamamoto, Masayoshi; Susuki, Yosuke; Taguchi, Akihiko; Tanabe, Katsuya; Kondo, Manabu; Hatanaka, Masayuki; Nagao, Yuko; Tanizawa, Yukio

    2013-05-03

    Highlights: •Arnt mRNA expressed in a circadian manner in mouse pancreatic islets. •Expressions of Dbp and Arnt damped in the islets of a diabetic model mouse. •DBP and E4BP4 regulate Arnt promoter activity by direct binding. •Arnt may have a role in connecting circadian rhythm and metabolism. -- Abstract: Aryl hydrocarbon receptor nuclear translocator (ARNT)/hypoxia inducible factor-1β (HIF-1β) has emerged as a potential determinant of pancreatic β-cell dysfunction and type 2 diabetes in humans. An 82% reduction in Arnt expression was observed in islets from type 2 diabetic donors as compared to non-diabetic donors. However, few regulators of Arnt expression have been identified. Meanwhile, disruption of the clock components CLOCK and BMAL1 is known to result in hypoinsulinemia and diabetes, but the molecular details remain unclear. In this study, we identified a novel molecular connection between Arnt and two clock-controlled output genes, albumin D-element binding protein (Dbp) and E4 binding protein 4 (E4bp4). By conducting gene expression studies using the islets of Wfs1{sup −/−} A{sup y}/a mice that develop severe diabetes due to β-cell apoptosis, we demonstrated clock-related gene expressions to be altered in the diabetic mice. Dbp mRNA decreased by 50%, E4bp4 mRNA increased by 50%, and Arnt mRNA decreased by 30% at Zeitgever Time (ZT) 12. Mouse pancreatic islets exhibited oscillations of clock gene expressions. E4BP4, a D-box negative regulator, oscillated anti-phase to DBP, a D-box positive regulator. We also found low-amplitude circadian expression of Arnt mRNA, which peaked at ZT4. Over-expression of DBP raised both mRNA and protein levels of ARNT in HEK293 and MIN6 cell lines. Arnt promoter-driven luciferase reporter assay in MIN6 cells revealed that DBP increased Arnt promoter activity by 2.5-fold and that E4BP4 competitively inhibited its activation. In addition, on ChIP assay, DBP and E4BP4 directly bound to D-box elements within the

  4. Clock-controlled output gene Dbp is a regulator of Arnt/Hif-1β gene expression in pancreatic islet β-cells.

    PubMed

    Nakabayashi, Hiroko; Ohta, Yasuharu; Yamamoto, Masayoshi; Susuki, Yosuke; Taguchi, Akihiko; Tanabe, Katsuya; Kondo, Manabu; Hatanaka, Masayuki; Nagao, Yuko; Tanizawa, Yukio

    2013-05-01

    Aryl hydrocarbon receptor nuclear translocator (ARNT)/hypoxia inducible factor-1β (HIF-1β) has emerged as a potential determinant of pancreatic β-cell dysfunction and type 2 diabetes in humans. An 82% reduction in Arnt expression was observed in islets from type 2 diabetic donors as compared to non-diabetic donors. However, few regulators of Arnt expression have been identified. Meanwhile, disruption of the clock components CLOCK and BMAL1 is known to result in hypoinsulinemia and diabetes, but the molecular details remain unclear. In this study, we identified a novel molecular connection between Arnt and two clock-controlled output genes, albumin D-element binding protein (Dbp) and E4 binding protein 4 (E4bp4). By conducting gene expression studies using the islets of Wfs1(-/-) A(y)/a mice that develop severe diabetes due to β-cell apoptosis, we demonstrated clock-related gene expressions to be altered in the diabetic mice. Dbp mRNA decreased by 50%, E4bp4 mRNA increased by 50%, and Arnt mRNA decreased by 30% at Zeitgever Time (ZT) 12. Mouse pancreatic islets exhibited oscillations of clock gene expressions. E4BP4, a D-box negative regulator, oscillated anti-phase to DBP, a D-box positive regulator. We also found low-amplitude circadian expression of Arnt mRNA, which peaked at ZT4. Over-expression of DBP raised both mRNA and protein levels of ARNT in HEK293 and MIN6 cell lines. Arnt promoter-driven luciferase reporter assay in MIN6 cells revealed that DBP increased Arnt promoter activity by 2.5-fold and that E4BP4 competitively inhibited its activation. In addition, on ChIP assay, DBP and E4BP4 directly bound to D-box elements within the Arnt promoter in MIN6 cells. These results suggest that in mouse pancreatic islets mRNA expression of Arnt fluctuates significantly in a circadian manner and that the down-regulation of Dbp and up-regulation E4bp4 contribute to direct suppression of Arnt expression in diabetes. PMID:23567972

  5. Pulsed Optically Pumped Rb clock

    NASA Astrophysics Data System (ADS)

    Micalizio, S.; Levi, F.; Godone, A.; Calosso, C. E.; François, B.; Boudot, R.; Affolderbach, C.; Kang, S.; Gharavipour, M.; Gruet, F.; Mileti, G.

    2016-06-01

    INRIM demonstrated a Rb vapour cell clock based on pulsed optical pumping (POP) with unprecedented frequency stability performances, both in the short and in the medium-long term period. In the frame of a EMRP project, we are developing a new clock based on the same POP principle but adopting solutions aimed at reducing the noise sources affecting the INRIM clock. At the same time, concerning possible technological applications, particular care are devoted in the project to reduce the size and the weight of the clock, still keeping the excellent stability of the INRIM clock. The paper resumes the main results of this activity.

  6. Daily expression of six clock genes in central and peripheral tissues of a night-migratory songbird: evidence for tissue-specific circadian timing.

    PubMed

    Singh, Devraj; Rani, Sangeeta; Kumar, Vinod

    2013-12-01

    In birds, independent circadian clocks reside in the retina, pineal, and hypothalamus, which interact with each other and produce circadian time at the functional level. However, less is known of the molecular clockwork, and of the integration between central and peripheral clocks in birds. The present study investigated this, by monitoring the timed expression of five core clock genes (Per2. Cry1. Cry2. Bmal1, and Clock) and one clock-controlled gene (E4bp4) in a night-migratory songbird, the redheaded bunting (rb; Emberiza bruniceps). The authors first partially cloned these six genes, and then measured their 24-h profiles in central (retina, hypothalamus) and peripheral (liver, heart, stomach, gut, testes) tissues, collected at six times (zeitgeber time 2 [ZT2], ZT6, ZT11, ZT13, ZT18, and ZT23; ZT0 = lights on) from birds (n = 5 per ZT) on 12 h:12 h light-dark cycle. rbPer2. rbCry1. rbBmal1, and rbClock were expressed with a significant rhythm in all the tissues, except in the retina (only rbClock) and testes. rbCry2, however, had tissue-specific expression pattern: a significant rhythm in the hypothalamus, heart, and gut, but not in the retina, liver, stomach, and testes. rbE4bp4 had a significant mRNA rhythm in all the tissues, except retina. Further, rbPer2 mRNA peak was phase aligned with lights on, whereas rbCry1. rbBmal1, and rbE4bp4 mRNA peaks were phase aligned with lights off. rbCry2 and rbClock had tissue-specific scattered peaks. For example, both rbCry2 and rbClock peaks were close to rbCry1 and rbBmal1 peaks, respectively, in the hypothalamus, but not in other tissues. The results are consistent with the autoregulatory circadian feedback loop, and indicate a conserved tissue-level circadian time generation in buntings. Variable phase relationships between gene pairs forming positive and negative limbs of the feedback loop may suggest the tissue-specific contribution of individual core circadian genes in the circadian time generation. PMID:23971885

  7. Effect and Regulatory Mechanism of Clock Gene Per1 on Biological Behaviors of Human Oral Squamous Carcinoma Cell.

    PubMed

    Han-Xue, L I; Kai, Yang; Xiao-Juan, F U; Qin, Zhao

    2016-04-10

    Objective To investigate the effect and regulatory mechanism of clock gene Per1 on the proliferation,apoptosis,migration,and invasion of human oral squamous carcinoma SCC15 cells. Methods RNA interference was used to knock down Per1 gene in human oral squamous cell carcinoma SCC15 cell line. Changes of cell proliferation and apoptosis were analyzed by flow cytometry. Transwell assay was carried out to assess cell migration and invasion. Real-time polymerase chain reaction was used to detect the mRNA expressions of Ki-67,murine double minute 2(MDM2),c-Myc,p53,Bax,Bcl-2,metalloproteinase (MMP)2,MMP9,and vascular endothelial growth factor (VEGF). Results shRNA-mediated knockdown of Per1 promoted the proliferation,migration and invasion capacity,and inhibited cell apoptosis capacity of SCC15 cells (all P<0.05). Additionally,Per1 knockdown also increased the mRNA expressions of Ki-67,MDM2,Bcl-2,MMP2,and MMP9 and decreased the mRNA expressions of c-Myc,p53,and Bax (all P<0.05);however,the VEGF mRNA expression did not differ significantly after Per1 knockdown (P>0.05). Conclusions Clock gene Perl can regulate important tumor-related genes downstream such as Ki-67,MDM2,c-Myc,p53,Bax,Bcl-2,MMP2,and MMP9,and the aberrant expression of Per1 can affect tumor cell proliferation,apoptosis,migration and invasion. An in-depth study of Per1 may further clarify the mechanism of tumorigenesis and tumor development and thus provides new effective molecular targets for cancer treatment. PMID:27181891

  8. Intercellular delay regulates the collective period of repressively coupled gene regulatory oscillator networks

    PubMed Central

    Wang, Yongqiang; Hori, Yutaka; Hara, Shinji; Doyle, Francis J.

    2013-01-01

    Most biological rhythms are generated by a population of cellular oscillators coupled through intercellular signaling. Recent experimental evidence shows that the collective period may differ significantly from the autonomous period in the presence of intercellular delays. The phenomenon has been investigated using delay-coupled phase oscillators, but the proposed phase model contains no direct biological mechanism, which may weaken the model's reliability in unraveling biophysical principles. Based on a published gene regulatory oscillator model, we analyze the collective period of delay-coupled biological oscillators using the multivariable harmonic balance technique. We prove that, in contradiction to the common intuition that the collective period increases linearly with the coupling delay, the collective period turns out to be a periodic function of the intercellular delay. More surprisingly, the collective period may even decrease with the intercellular delay when the delay resides in certain regions. The collective period is given in a closed-form in terms of biochemical reaction constants and thus provides biological insights as well as guidance in synthetic-biological-oscillator design. Simulation results are given based on a segmentation clock model to confirm the theoretical predictions. PMID:25346544

  9. Machine Learning Helps Identify CHRONO as a Circadian Clock Component

    PubMed Central

    Venkataraman, Anand; Ramanathan, Chidambaram; Kavakli, Ibrahim H.; Hughes, Michael E.; Baggs, Julie E.; Growe, Jacqueline; Liu, Andrew C.; Kim, Junhyong; Hogenesch, John B.

    2014-01-01

    Over the last decades, researchers have characterized a set of “clock genes” that drive daily rhythms in physiology and behavior. This arduous work has yielded results with far-reaching consequences in metabolic, psychiatric, and neoplastic disorders. Recent attempts to expand our understanding of circadian regulation have moved beyond the mutagenesis screens that identified the first clock components, employing higher throughput genomic and proteomic techniques. In order to further accelerate clock gene discovery, we utilized a computer-assisted approach to identify and prioritize candidate clock components. We used a simple form of probabilistic machine learning to integrate biologically relevant, genome-scale data and ranked genes on their similarity to known clock components. We then used a secondary experimental screen to characterize the top candidates. We found that several physically interact with known clock components in a mammalian two-hybrid screen and modulate in vitro cellular rhythms in an immortalized mouse fibroblast line (NIH 3T3). One candidate, Gene Model 129, interacts with BMAL1 and functionally represses the key driver of molecular rhythms, the BMAL1/CLOCK transcriptional complex. Given these results, we have renamed the gene CHRONO (computationally highlighted repressor of the network oscillator). Bi-molecular fluorescence complementation and co-immunoprecipitation demonstrate that CHRONO represses by abrogating the binding of BMAL1 to its transcriptional co-activator CBP. Most importantly, CHRONO knockout mice display a prolonged free-running circadian period similar to, or more drastic than, six other clock components. We conclude that CHRONO is a functional clock component providing a new layer of control on circadian molecular dynamics. PMID:24737000

  10. Transcriptional regulation via nuclear receptor crosstalk required for the Drosophila circadian clock.

    PubMed

    Jaumouillé, Edouard; Machado Almeida, Pedro; Stähli, Patrick; Koch, Rafael; Nagoshi, Emi

    2015-06-01

    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. PMID:26004759