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Pierre-Ferrer S, Collins B, Lukacsovich D, Wen S, Cai Y, Winterer J, Yan J, Pedersen L, Földy C, Brown SA. A phosphate transporter in VIPergic neurons of the suprachiasmatic nucleus gates locomotor activity during the light/dark transition in mice. Cell Rep 2024; 43:114220. [PMID: 38735047 DOI: 10.1016/j.celrep.2024.114220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 02/23/2024] [Accepted: 04/25/2024] [Indexed: 05/14/2024] Open
Abstract
The suprachiasmatic nucleus (SCN) encodes time of day through changes in daily firing; however, the molecular mechanisms by which the SCN times behavior are not fully understood. To identify factors that could encode day/night differences in activity, we combine patch-clamp recordings and single-cell sequencing of individual SCN neurons in mice. We identify PiT2, a phosphate transporter, as being upregulated in a population of Vip+Nms+ SCN neurons at night. Although nocturnal and typically showing a peak of activity at lights off, mice lacking PiT2 (PiT2-/-) do not reach the activity level seen in wild-type mice during the light/dark transition. PiT2 loss leads to increased SCN neuronal firing and broad changes in SCN protein phosphorylation. PiT2-/- mice display a deficit in seasonal entrainment when moving from a simulated short summer to longer winter nights. This suggests that PiT2 is responsible for timing activity and is a driver of SCN plasticity allowing seasonal entrainment.
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Affiliation(s)
- Sara Pierre-Ferrer
- Chronobiology and Sleep Research Group, Institute of Pharmacology and Toxicology, Faculties of Medicine and Science, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
| | - Ben Collins
- Chronobiology and Sleep Research Group, Institute of Pharmacology and Toxicology, Faculties of Medicine and Science, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland; Department of Biology, Sacred Heart University, 5151 Park Ave., Fairfield, CT 06825, USA
| | - David Lukacsovich
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Shao'Ang Wen
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yuchen Cai
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jochen Winterer
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Jun Yan
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Lene Pedersen
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000 Aarhus, Denmark
| | - Csaba Földy
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
| | - Steven A Brown
- Chronobiology and Sleep Research Group, Institute of Pharmacology and Toxicology, Faculties of Medicine and Science, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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2
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Bonnefont X. Cell Signaling in the Circadian Pacemaker: New Insights from in vivo Imaging. Neuroendocrinology 2024:1-8. [PMID: 38754404 DOI: 10.1159/000539344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 05/12/2024] [Indexed: 05/18/2024]
Abstract
BACKGROUND "One for all, and all for one," the famous rallying cry of the Three Musketeers, in Alexandre Dumas's popular novel, certainly applies to the 20,000 cells composing the suprachiasmatic nuclei (SCN). These cells work together to form the central clock that coordinates body rhythms in tune with the day-night cycle. Like virtually every body cell, individual SCN cells exhibit autonomous circadian oscillations, but this rhythmicity only reaches a high level of precision and robustness when the cells are coupled with their neighbors. Therefore, understanding the functional network organization of SCN cells beyond their core rhythmicity is an important issue in circadian biology. SUMMARY The present review summarizes the main results from our recent study demonstrating the feasibility of recording SCN cells in freely moving mice and the significance of variations in intracellular calcium over several timescales. KEY MESSAGE We discuss how in vivo imaging at the cell level will be pivotal to interrogate the mammalian master clock, in an integrated context that preserves the SCN network organization, with intact inputs and outputs.
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Affiliation(s)
- Xavier Bonnefont
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
- BioCampus Montpellier, Université de Montpellier, CNRS, INSERM, Montpellier, France
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3
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Cox OH, Gianonni-Guzmán MA, Cartailler JP, Cottam MA, McMahon DG. Gene expression plasticity of the mammalian brain circadian clock in response to photoperiod. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.16.580759. [PMID: 38586021 PMCID: PMC10996532 DOI: 10.1101/2024.02.16.580759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Seasonal daylength, or circadian photoperiod, is a pervasive environmental signal that profoundly influences physiology and behavior. In mammals, the central circadian clock resides in the suprachiasmatic nuclei (SCN) of the hypothalamus where it receives retinal input and synchronizes, or entrains, organismal physiology and behavior to the prevailing light cycle. The process of entrainment induces sustained plasticity in the SCN, but the molecular mechanisms underlying SCN plasticity are incompletely understood. Entrainment to different photoperiods persistently alters the timing, waveform, period, and light resetting properties of the SCN clock and its driven rhythms. To elucidate novel molecular mechanisms of photoperiod plasticity, we performed RNAseq on whole SCN dissected from mice raised in Long (LD 16:8) and Short (LD 8:16) photoperiods. Fewer rhythmic genes were detected in Long photoperiod and in general the timing of gene expression rhythms was advanced 4-6 hours. However, a few genes showed significant delays, including Gem . There were significant changes in the expression clock-associated gene Timeless and in SCN genes related to light responses, neuropeptides, GABA, ion channels, and serotonin. Particularly striking were differences in the expression of the neuropeptide signaling genes Prokr2 and Cck , as well as convergent regulation of the expression of three SCN light response genes, Dusp4 , Rasd1 , and Gem . Transcriptional modulation of Dusp4 and Rasd1, and phase regulation of Gem, are compelling candidate molecular mechanisms for plasticity in the SCN light response through their modulation of the critical NMDAR-MAPK/ERK-CREB/CRE light signaling pathway in SCN neurons. Modulation of Prokr2 and Cck may critically support SCN neural network reconfiguration during photoperiodic entrainment. Our findings identify the SCN light response and neuropeptide signaling gene sets as rich substrates for elucidating novel mechanisms of photoperiod plasticity.
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Schmal C. The seasons within: a theoretical perspective on photoperiodic entrainment and encoding. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023:10.1007/s00359-023-01669-z. [PMID: 37659985 DOI: 10.1007/s00359-023-01669-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 08/11/2023] [Accepted: 08/16/2023] [Indexed: 09/04/2023]
Abstract
Circadian clocks are internal timing devices that have evolved as an adaption to the omnipresent natural 24 h rhythmicity of daylight intensity. Properties of the circadian system are photoperiod dependent. The phase of entrainment varies systematically with season. Plastic photoperiod-dependent re-arrangements in the mammalian circadian core pacemaker yield an internal representation of season. Output pathways of the circadian clock regulate photoperiodic responses such as flowering time in plants or hibernation in mammals. Here, we review the concepts of seasonal entrainment and photoperiodic encoding. We introduce conceptual phase oscillator models as their high level of abstraction, but, yet, intuitive interpretation of underlying parameters allows for a straightforward analysis of principles that determine entrainment characteristics. Results from this class of models are related and discussed in the context of more complex conceptual amplitude-phase oscillators as well as contextual molecular models that take into account organism, tissue, and cell-type-specific details.
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Affiliation(s)
- Christoph Schmal
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Philippstr. 13, 10115, Berlin, Germany.
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5
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Lear CA, Maeda Y, King VJ, Dhillon SK, Beacom MJ, Gunning MI, Lear BA, Davidson JO, Stone PR, Ikeda T, Gunn AJ, Bennet L. Circadian patterns of heart rate variability in fetal sheep after hypoxia-ischaemia: A biomarker of evolving brain injury. J Physiol 2023. [PMID: 37432936 DOI: 10.1113/jp284560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 06/23/2023] [Indexed: 07/13/2023] Open
Abstract
Hypoxia-ischaemia (HI) before birth is a key risk factor for stillbirth and severe neurodevelopmental disability in survivors, including cerebral palsy, although there are no reliable biomarkers to detect at risk fetuses that may have suffered a transient period of severe HI. We investigated time and frequency domain measures of fetal heart rate variability (FHRV) for 3 weeks after HI in preterm fetal sheep at 0.7 gestation (equivalent to preterm humans) until 0.8 gestation (equivalent to term humans). We have previously shown that this is associated with delayed development of severe white and grey matter injury, including cystic white matter injury (WMI) resembling that observed in human preterm infants. HI was associated with suppression of time and frequency domain measures of FHRV and reduced their circadian rhythmicity during the first 3 days of recovery. By contrast, circadian rhythms of multiple measures of FHRV were exaggerated over the final 2 weeks of recovery, mediated by a greater reduction in FHRV during the morning nadir, but no change in the evening peak. These data suggest that the time of day at which FHRV measurements are taken affects their diagnostic utility. We further propose that circadian changes in FHRV may be a low-cost, easily applied biomarker of antenatal HI and evolving brain injury. KEY POINTS: Hypoxia-ischaemia (HI) before birth is a key risk factor for stillbirth and probably for disability in survivors, although there are no reliable biomarkers for antenatal brain injury. In preterm fetal sheep, acute HI that is known to lead to delayed development of severe white and grey matter injury over 3 weeks, was associated with early suppression of multiple time and frequency domain measures of fetal heart rate variability (FHRV) and loss of their circadian rhythms during the first 3 days after HI. Over the final 2 weeks of recovery after HI, exaggerated circadian rhythms of frequency domain FHRV measures were observed. The morning nadirs were lower with no change in the evening peak of FHRV. Circadian changes in FHRV may be a low-cost, easily applied biomarker of antenatal HI and evolving brain injury.
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Affiliation(s)
- Christopher A Lear
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
| | - Yoshiki Maeda
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
- The Department of Obstetrics and Gynaecology, Mie University, Mie, Japan
| | - Victoria J King
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
| | - Simerdeep K Dhillon
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
| | - Michael J Beacom
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
| | - Mark I Gunning
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
| | - Benjamin A Lear
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
| | - Peter R Stone
- The Department of Obstetrics and Gynaecology, The University of Auckland, Auckland, New Zealand
| | - Tomoaki Ikeda
- The Department of Obstetrics and Gynaecology, Mie University, Mie, Japan
| | - Alistair J Gunn
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, Fetal Physiology and Neuroscience Group, The University of Auckland, Auckland, New Zealand
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6
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Joye DAM, Rohr KE, Suenkens K, Wuorinen A, Inda T, Arzbecker M, Mueller E, Huber A, Pancholi H, Blackmore MG, Carmona-Alcocer V, Evans JA. Somatostatin regulates central clock function and circadian responses to light. Proc Natl Acad Sci U S A 2023; 120:e2216820120. [PMID: 37098068 PMCID: PMC10160998 DOI: 10.1073/pnas.2216820120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 03/21/2023] [Indexed: 04/26/2023] Open
Abstract
Daily and annual changes in light are processed by central clock circuits that control the timing of behavior and physiology. The suprachiasmatic nucleus (SCN) in the anterior hypothalamus processes daily photic inputs and encodes changes in day length (i.e., photoperiod), but the SCN circuits that regulate circadian and photoperiodic responses to light remain unclear. Somatostatin (SST) expression in the hypothalamus is modulated by photoperiod, but the role of SST in SCN responses to light has not been examined. Our results indicate that SST signaling regulates daily rhythms in behavior and SCN function in a manner influenced by sex. First, we use cell-fate mapping to provide evidence that SST in the SCN is regulated by light via de novo Sst activation. Next, we demonstrate that Sst -/- mice display enhanced circadian responses to light, with increased behavioral plasticity to photoperiod, jetlag, and constant light conditions. Notably, lack of Sst -/- eliminated sex differences in photic responses due to increased plasticity in males, suggesting that SST interacts with clock circuits that process light differently in each sex. Sst -/- mice also displayed an increase in the number of retinorecipient neurons in the SCN core, which express a type of SST receptor capable of resetting the molecular clock. Last, we show that lack of SST signaling modulates central clock function by influencing SCN photoperiodic encoding, network after-effects, and intercellular synchrony in a sex-specific manner. Collectively, these results provide insight into peptide signaling mechanisms that regulate central clock function and its response to light.
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Affiliation(s)
- Deborah A. M. Joye
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
| | - Kayla E. Rohr
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
| | - Kimberlee Suenkens
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
| | - Alissa Wuorinen
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
| | - Thomas Inda
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
| | - Madeline Arzbecker
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
| | - Emma Mueller
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
| | - Alec Huber
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
| | - Harshida Pancholi
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
| | | | | | - Jennifer A. Evans
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI53233
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7
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Schibler U, Dibner C, Ripperger J. Steve Brown. J Biol Rhythms 2023; 38:119-124. [PMID: 36762620 PMCID: PMC10037542 DOI: 10.1177/07487304231152275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- Ueli Schibler
- Ueli Schibler, Department
of Molecular and Cellular Biology, University of Geneva, 30, Quai Ernest
Ansermet, Geneva, CH-1211, Switzerland; e-mail:
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8
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Kompotis K, Landolt HP. In memoriam: Professor Steven A. Brown, PhD (1970-2022). J Sleep Res 2023:e13836. [PMID: 36756725 DOI: 10.1111/jsr.13836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 01/12/2023] [Indexed: 02/10/2023]
Affiliation(s)
- Konstantinos Kompotis
- Section of Chronobiology and Sleep Research, Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland
| | - Hans-Peter Landolt
- Section of Chronobiology and Sleep Research, Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland
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9
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Schwartz MD, Cambras T, Díez-Noguera A, Campuzano A, Oda GA, Yamazaki S, de la Iglesia HO. Coupling Between Subregional Oscillators Within the Suprachiasmatic Nucleus Determines Free-Running Period in the Rat. J Biol Rhythms 2022; 37:620-630. [PMID: 36181312 PMCID: PMC10001112 DOI: 10.1177/07487304221126074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Rats housed in a 22-h light-dark cycle (11:11, T22) exhibit 2 distinct circadian locomotor activity (LMA) bouts simultaneously: one is entrained to the LD cycle and a second dissociated bout maintains a period greater than 24 h. These 2 activity bouts are associated with independent clock gene oscillations in the ventrolateral (vl-) and dorsomedial (dm-) suprachiasmatic nucleus (SCN), respectively. Previous results in our laboratory have shown that the vl- and dm-SCN oscillators are weakly coupled under T22 and that the period of the dissociated bout depends on coupling between the 2 subdivisions. Here, we sought to study the behavior of the T22 SCN pacemaker upon release into free-running conditions and compare it to the behavior of the system upon release from typical 24-h (12:12, T24) entrainment. T22-desynchronized rats or T24-entrained rats were released into constant darkness (DD). Activity rhythms in T22 rats rapidly resynchronized upon release into DD, and the free-running period (FRP) of the fused rhythm was longer than the FRP of T24 rats. We then asked whether the in vivo period changes were also present in the ex vivo SCN. Per1-luc rats were desynchronized in T22 for assessment of SCN Per1-luc ex vivo. Similar to behavioral FRP, the period of ex vivo SCN explanted from T22 rats was longer than that for T24 animals. Mathematical models supported the observed behavior of the dual oscillator system as the result of mutual coupling between the vl- and dm-SCN oscillators. This bidirectionally coupled model predicted both the FRP of the T22 system and its phase-shifting response to light. Together, these data support a model of pacemaker organization in which a light-sensitive vl-SCN oscillator is mutually coupled with a light-insensitive dm-SCN oscillator, and together they determine the period of the coupled system as a whole and its response to light pulses.
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Affiliation(s)
- Michael D Schwartz
- Department of Biology and Graduate Program in Neuroscience, University of Washington, Seattle, Washington, USA
| | - Trinitat Cambras
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
| | - Antoni Díez-Noguera
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
| | - Ana Campuzano
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
| | - Gisele A Oda
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Shin Yamazaki
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Horacio O de la Iglesia
- Department of Biology and Graduate Program in Neuroscience, University of Washington, Seattle, Washington, USA
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10
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Tacad DKM, Tovar AP, Richardson CE, Horn WF, Keim NL, Krishnan GP, Krishnan S. Satiety Associated with Calorie Restriction and Time-Restricted Feeding: Central Neuroendocrine Integration. Adv Nutr 2022; 13:758-791. [PMID: 35134815 PMCID: PMC9156369 DOI: 10.1093/advances/nmac011] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 12/08/2021] [Accepted: 02/02/2022] [Indexed: 02/06/2023] Open
Abstract
This review focuses on summarizing current knowledge on how time-restricted feeding (TRF) and continuous caloric restriction (CR) affect central neuroendocrine systems involved in regulating satiety. Several interconnected regions of the hypothalamus, brainstem, and cortical areas of the brain are involved in the regulation of satiety. Following CR and TRF, the increase in hunger and reduction in satiety signals of the melanocortin system [neuropeptide Y (NPY), proopiomelanocortin (POMC), and agouti-related peptide (AgRP)] appear similar between CR and TRF protocols, as do the dopaminergic responses in the mesocorticolimbic circuit. However, ghrelin and leptin signaling via the melanocortin system appears to improve energy balance signals and reduce hyperphagia following TRF, which has not been reported in CR. In addition to satiety systems, CR and TRF also influence circadian rhythms. CR influences the suprachiasmatic nucleus (SCN) or the primary circadian clock as seen by increased clock gene expression. In contrast, TRF appears to affect both the SCN and the peripheral clocks, as seen by phasic changes in the non-SCN (potentially the elusive food entrainable oscillator) and metabolic clocks. The peripheral clocks are influenced by the primary circadian clock but are also entrained by food timing, sleep timing, and other lifestyle parameters, which can supersede the metabolic processes that are regulated by the primary circadian clock. Taken together, TRF influences hunger/satiety, energy balance systems, and circadian rhythms, suggesting a role for adherence to CR in the long run if implemented using the TRF approach. However, these suggestions are based on only a few studies, and future investigations that use standardized protocols for the evaluation of the effect of these diet patterns (time, duration, meal composition, sufficiently powered) are necessary to verify these preliminary observations.
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Affiliation(s)
- Debra K M Tacad
- Obesity and Metabolism Research Unit, USDA–Western Human Nutrition Research Center, Davis, CA, USA,Department of Nutrition, University of California, Davis, Davis, CA, USA
| | - Ashley P Tovar
- Department of Nutrition, University of California, Davis, Davis, CA, USA
| | | | - William F Horn
- Obesity and Metabolism Research Unit, USDA–Western Human Nutrition Research Center, Davis, CA, USA
| | - Nancy L Keim
- Obesity and Metabolism Research Unit, USDA–Western Human Nutrition Research Center, Davis, CA, USA,Department of Nutrition, University of California, Davis, Davis, CA, USA
| | - Giri P Krishnan
- Department of Medicine, School of Medicine, University of California, San Diego, San Diego, CA, USA
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11
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Zhou J, Wang H, Ouyang Q. Network rewiring and plasticity promotes synchronization of suprachiasmatic nucleus neurons. CHAOS (WOODBURY, N.Y.) 2022; 32:023101. [PMID: 35232040 DOI: 10.1063/5.0073480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 01/17/2022] [Indexed: 06/14/2023]
Abstract
In mammals, circadian rhythms throughout the body are orchestrated by the master clock in the hypothalamic suprachiasmatic nucleus (SCN), where SCN neurons are coupled with neurotransmitters to generate a uniform circadian rhythm. How the SCN circadian rhythm is so robust and flexible is, however, unclear. In this paper, we propose a temporal SCN network model and investigate the effects of dynamical rewiring and flexible coupling due to synaptic plasticity on the synchronization of the neural network in SCN. In networks consisting of simple Poincaré oscillators and complex circadian clocks, we found that dynamical rewiring and coupling plasticity enhance the synchronization in inhomogeneous networks. We verified the effect of enhanced synchronization in different architectures of random, scale-free, and small-world networks. A simple mean-field analysis for synchronization in plastic networks is proposed. Intuitively, the synchronization is greatly enhanced because both the random rewiring and coupling plasticity in the heterogeneous network have effectively increased the coupling strength in the whole network. Our results suggest that a proper network model for the master SCN circadian rhythm needs to take into account the effects of dynamical changes in topology and plasticity in neuron interactions that could help the brain to generate a robust circadian rhythm for the whole body.
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Affiliation(s)
- Jiaxin Zhou
- The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Hongli Wang
- The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Qi Ouyang
- The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
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12
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Kim S, McMahon DG. Light sets the brain's daily clock by regional quickening and slowing of the molecular clockworks at dawn and dusk. eLife 2021; 10:70137. [PMID: 34927581 PMCID: PMC8687663 DOI: 10.7554/elife.70137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 12/11/2021] [Indexed: 12/15/2022] Open
Abstract
How daily clocks in the brain are set by light to local environmental time and encode the seasons is not fully understood. The suprachiasmatic nucleus (SCN) is a central circadian clock in mammals that orchestrates physiology and behavior in tune with daily and seasonal light cycles. Here, we have found that optogenetically simulated light input to explanted mouse SCN changes the waveform of the molecular clockworks from sinusoids in free-running conditions to highly asymmetrical shapes with accelerated synthetic (rising) phases and extended degradative (falling) phases marking clock advances and delays at simulated dawn and dusk. Daily waveform changes arise under ex vivo entrainment to simulated winter and summer photoperiods, and to non-24 hr periods. Ex vivo SCN imaging further suggests that acute waveform shifts are greatest in the ventrolateral SCN, while period effects are greatest in the dorsomedial SCN. Thus, circadian entrainment is encoded by SCN clock gene waveform changes that arise from spatiotemporally distinct intrinsic responses within the SCN neural network.
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Affiliation(s)
- Suil Kim
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, United States
| | - Douglas G McMahon
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, United States.,Department of Biological Sciences, Vanderbilt University, Nashville, United States
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13
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Saad L, Kalsbeek A, Zwiller J, Anglard P. Rhythmic Regulation of DNA Methylation Factors and Core-Clock Genes in Brain Structures Activated by Cocaine or Sucrose: Potential Role of Chromatin Remodeling. Genes (Basel) 2021; 12:genes12081195. [PMID: 34440369 PMCID: PMC8392220 DOI: 10.3390/genes12081195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/25/2022] Open
Abstract
The circadian system interacts with the mesocorticolimbic reward system to modulate reward and memory in a time-of-day dependent manner. The circadian discrimination of reward, however, remains difficult to address between natural reinforcers and drugs of abuse. Circadian rhythms control cocaine sensitization and conversely cocaine causes long-term alteration in circadian periodicity in part through the serotonergic neurotransmission. Since neural circuits activated by cocaine and natural reinforcers do not completely overlap, we compared the effect of cocaine with that of sucrose, a strong reinforcer in rodents, by using passive chronic administration. The expression of fifteen genes playing a major role in DNA methylation (Dnmts, Tets), circadian rhythms (Clock, Bmal1, Per1/2, Cry1/2, Rev-Erbβ, Dbp1), appetite, and satiety (Orexin, Npy) was analyzed in dopamine projection areas like the prefrontal cortex, the caudate putamen, and the hypothalamus interconnected with the reward system. The corresponding proteins of two genes (Orexin, Per2) were examined by IHC. For many factors controlling biological and cognitive functions, striking opposite responses were found between the two reinforcers, notably for genes controlling DNA methylation/demethylation processes and in global DNA methylation involved in chromatin remodeling. The data are consistent with a repression of critical core-clock genes by cocaine, suggesting that, consequently, both agents differentially modulate day/night cycles. Whether observed cocaine and sucrose-induced changes in DNA methylation in a time dependent manner are long lasting or contribute to the establishment of addiction requires further neuroepigenetic investigation. Understanding the mechanisms dissociating drugs of abuse from natural reinforcers remains a prerequisite for the design of selective therapeutic tools for compulsive behaviors.
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Affiliation(s)
- Lamis Saad
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), UMR 7364 CNRS, Université de Strasbourg, Neuropôle de Strasbourg, 67000 Strasbourg, France; (L.S.); (J.Z.)
- The Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, 1066 EA Amsterdam, The Netherlands
| | - Andries Kalsbeek
- The Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, 1066 EA Amsterdam, The Netherlands
- Correspondence: (A.K.); or (P.A.)
| | - Jean Zwiller
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), UMR 7364 CNRS, Université de Strasbourg, Neuropôle de Strasbourg, 67000 Strasbourg, France; (L.S.); (J.Z.)
- CNRS, Centre National de la Recherche Scientifique, 75016 Paris, France
| | - Patrick Anglard
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), UMR 7364 CNRS, Université de Strasbourg, Neuropôle de Strasbourg, 67000 Strasbourg, France; (L.S.); (J.Z.)
- INSERM, Institut National de la Santé et de la Recherche Médicale, 75013 Paris, France
- Correspondence: (A.K.); or (P.A.)
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14
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Hughes ATL, Samuels RE, Baño-Otálora B, Belle MDC, Wegner S, Guilding C, Northeast RC, Loudon ASI, Gigg J, Piggins HD. Timed daily exercise remodels circadian rhythms in mice. Commun Biol 2021; 4:761. [PMID: 34145388 PMCID: PMC8213798 DOI: 10.1038/s42003-021-02239-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 05/18/2021] [Indexed: 01/26/2023] Open
Abstract
Regular exercise is important for physical and mental health. An underexplored and intriguing property of exercise is its actions on the body’s 24 h or circadian rhythms. Molecular clock cells in the brain’s suprachiasmatic nuclei (SCN) use electrical and chemical signals to orchestrate their activity and convey time of day information to the rest of the brain and body. To date, the long-lasting effects of regular physical exercise on SCN clock cell coordination and communication remain unresolved. Utilizing mouse models in which SCN intercellular neuropeptide signaling is impaired as well as those with intact SCN neurochemical signaling, we examined how daily scheduled voluntary exercise (SVE) influenced behavioral rhythms and SCN molecular and neuronal activities. We show that in mice with disrupted neuropeptide signaling, SVE promotes SCN clock cell synchrony and robust 24 h rhythms in behavior. Interestingly, in both intact and neuropeptide signaling deficient animals, SVE reduces SCN neural activity and alters GABAergic signaling. These findings illustrate the potential utility of regular exercise as a long-lasting and effective non-invasive intervention in the elderly or mentally ill where circadian rhythms can be blunted and poorly aligned to the external world. Using mice with disrupted neuropeptide signaling, Hughes et al. show that daily scheduled voluntary exercise (SVE) promotes suprachiasmatic nuclei (SCN) clock cell synchrony and robust 24 h rhythms in behavior. This study suggests the potential utility of regular exercise as a non-invasive intervention for the elderly or mentally ill, where circadian rhythms can be poorly aligned to the external world.
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Affiliation(s)
- Alun Thomas Lloyd Hughes
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
| | - Rayna Eve Samuels
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Beatriz Baño-Otálora
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Mino David Charles Belle
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,University of Exeter Medical School, Exeter, UK
| | - Sven Wegner
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Clare Guilding
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,School of Medical Education, Newcastle University, Newcastle, UK
| | | | | | - John Gigg
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Hugh David Piggins
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK. .,School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, UK.
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15
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Nave C, Roberts L, Hwu P, Estrella JD, Vo TC, Nguyen TH, Bui TT, Rindner DJ, Pervolarakis N, Shaw PJ, Leise TL, Holmes TC. Weekend Light Shifts Evoke Persistent Drosophila Circadian Neural Network Desynchrony. J Neurosci 2021; 41:5173-5189. [PMID: 33931552 PMCID: PMC8211545 DOI: 10.1523/jneurosci.3074-19.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 11/21/2022] Open
Abstract
We developed a method for single-cell resolution longitudinal bioluminescence imaging of PERIOD (PER) protein and TIMELESS (TIM) oscillations in cultured male adult Drosophila brains that captures circadian circuit-wide cycling under simulated day/night cycles. Light input analysis confirms that CRYPTOCHROME (CRY) is the primary circadian photoreceptor and mediates clock disruption by constant light (LL), and that eye light input is redundant to CRY; 3-h light phase delays (Friday) followed by 3-h light phase advances (Monday morning) simulate the common practice of staying up later at night on weekends, sleeping in later on weekend days then returning to standard schedule Monday morning [weekend light shift (WLS)]. PER and TIM oscillations are highly synchronous across all major circadian neuronal subgroups in unshifted light schedules for 11 d. In contrast, WLS significantly dampens PER oscillator synchrony and rhythmicity in most circadian neurons during and after exposure. Lateral ventral neuron (LNv) oscillations are the first to desynchronize in WLS and the last to resynchronize in WLS. Surprisingly, the dorsal neuron group-3 (DN3s) increase their within-group synchrony in response to WLS. In vivo, WLS induces transient defects in sleep stability, learning, and memory that temporally coincide with circuit desynchrony. Our findings suggest that WLS schedules disrupt circuit-wide circadian neuronal oscillator synchrony for much of the week, thus leading to observed behavioral defects in sleep, learning, and memory.
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Affiliation(s)
- Ceazar Nave
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Logan Roberts
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Patrick Hwu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Jerson D Estrella
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Thanh C Vo
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Thanh H Nguyen
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Tony Thai Bui
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Daniel J Rindner
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Nicholas Pervolarakis
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California 92697
| | - Paul J Shaw
- Department of Anatomy and Neurobiology, Washington University in St. Louis, St. Louis, Missouri 63110
| | - Tanya L Leise
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts 01002
| | - Todd C Holmes
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
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16
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Tian W, Wang R, Bo C, Yu Y, Zhang Y, Shin GI, Kim WY, Wang L. SDC mediates DNA methylation-controlled clock pace by interacting with ZTL in Arabidopsis. Nucleic Acids Res 2021; 49:3764-3780. [PMID: 33675668 PMCID: PMC8053106 DOI: 10.1093/nar/gkab128] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 02/13/2021] [Accepted: 02/16/2021] [Indexed: 12/29/2022] Open
Abstract
Molecular bases of eukaryotic circadian clocks mainly rely on transcriptional-translational feedback loops (TTFLs), while epigenetic codes also play critical roles in fine-tuning circadian rhythms. However, unlike histone modification codes that play extensive and well-known roles in the regulation of circadian clocks, whether DNA methylation (5mC) can affect the circadian clock, and the associated underlying molecular mechanisms, remains largely unexplored in many organisms. Here we demonstrate that global genome DNA hypomethylation can significantly lengthen the circadian period of Arabidopsis. Transcriptomic and genetic evidence demonstrate that SUPPRESSOR OF drm1 drm2 cmt3 (SDC), encoding an F-box containing protein, is required for the DNA hypomethylation-tuned circadian clock. Moreover, SDC can physically interact with another F-box containing protein ZEITLUPE (ZTL) to diminish its accumulation. Genetic analysis further revealed that ZTL and its substrate TIMING OF CAB EXPRESSION 1 (TOC1) likely act downstream of DNA methyltransferases to control circadian rhythm. Together, our findings support the notion that DNA methylation is important to maintain proper circadian pace in Arabidopsis, and further established that SDC links DNA hypomethylation with a proteolytic cascade to assist in tuning the circadian clock.
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Affiliation(s)
- Wenwen Tian
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Ruyi Wang
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
| | - Cunpei Bo
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yingjun Yu
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yuanyuan Zhang
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
| | - Gyeong-Im Shin
- Division of Applied Life Science (BK21Plus), Research Institute of Life Sciences (RILS) and Institute of Agricultural and Life Science(IALS), Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Woe-Yeon Kim
- Division of Applied Life Science (BK21Plus), Research Institute of Life Sciences (RILS) and Institute of Agricultural and Life Science(IALS), Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Lei Wang
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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17
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Kostin A, Alam MA, McGinty D, Alam MN. Adult hypothalamic neurogenesis and sleep-wake dysfunction in aging. Sleep 2021; 44:5986548. [PMID: 33202015 DOI: 10.1093/sleep/zsaa173] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/22/2020] [Indexed: 12/21/2022] Open
Abstract
In the mammalian brain, adult neurogenesis has been extensively studied in the hippocampal sub-granular zone and the sub-ventricular zone of the anterolateral ventricles. However, growing evidence suggests that new cells are not only "born" constitutively in the adult hypothalamus, but many of these cells also differentiate into neurons and glia and serve specific functions. The preoptic-hypothalamic area plays a central role in the regulation of many critical functions, including sleep-wakefulness and circadian rhythms. While a role for adult hippocampal neurogenesis in regulating hippocampus-dependent functions, including cognition, has been extensively studied, adult hypothalamic neurogenic process and its contributions to various hypothalamic functions, including sleep-wake regulation are just beginning to unravel. This review is aimed at providing the current understanding of the hypothalamic adult neurogenic processes and the extent to which it affects hypothalamic functions, including sleep-wake regulation. We propose that hypothalamic neurogenic processes are vital for maintaining the proper functioning of the hypothalamic sleep-wake and circadian systems in the face of regulatory challenges. Sleep-wake disturbance is a frequent and challenging problem of aging and age-related neurodegenerative diseases. Aging is also associated with a decline in the neurogenic process. We discuss a hypothesis that a decrease in the hypothalamic neurogenic process underlies the aging of its sleep-wake and circadian systems and associated sleep-wake disturbance. We further discuss whether neuro-regenerative approaches, including pharmacological and non-pharmacological stimulation of endogenous neural stem and progenitor cells in hypothalamic neurogenic niches, can be used for mitigating sleep-wake and other hypothalamic dysfunctions in aging.
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Affiliation(s)
- Andrey Kostin
- Research Service (151A3), Veterans Affairs Greater Los Angeles Healthcare System, Sepulveda, CA
| | - Md Aftab Alam
- Research Service (151A3), Veterans Affairs Greater Los Angeles Healthcare System, Sepulveda, CA.,Department of Psychiatry, University of California, Los Angeles, CA
| | - Dennis McGinty
- Research Service (151A3), Veterans Affairs Greater Los Angeles Healthcare System, Sepulveda, CA.,Department of Psychology, University of California, Los Angeles, CA
| | - Md Noor Alam
- Research Service (151A3), Veterans Affairs Greater Los Angeles Healthcare System, Sepulveda, CA.,Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA
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18
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Tinarelli F, Ivanova E, Colombi I, Barini E, Balzani E, Garcia CG, Gasparini L, Chiappalone M, Kelsey G, Tucci V. Cell-cell coupling and DNA methylation abnormal phenotypes in the after-hours mice. Epigenetics Chromatin 2021; 14:1. [PMID: 33407878 PMCID: PMC7789812 DOI: 10.1186/s13072-020-00373-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Accepted: 11/13/2020] [Indexed: 11/10/2022] Open
Abstract
Background DNA methylation has emerged as an important epigenetic regulator of brain processes, including circadian rhythms. However, how DNA methylation intervenes between environmental signals, such as light entrainment, and the transcriptional and translational molecular mechanisms of the cellular clock is currently unknown. Here, we studied the after-hours mice, which have a point mutation in the Fbxl3 gene and a lengthened circadian period. Methods In this study, we used a combination of in vivo, ex vivo and in vitro approaches. We measured retinal responses in Afh animals and we have run reduced representation bisulphite sequencing (RRBS), pyrosequencing and gene expression analysis in a variety of brain tissues ex vivo. In vitro, we used primary neuronal cultures combined to micro electrode array (MEA) technology and gene expression. Results We observed functional impairments in mutant neuronal networks, and a reduction in the retinal responses to light-dependent stimuli. We detected abnormalities in the expression of photoreceptive melanopsin (OPN4). Furthermore, we identified alterations in the DNA methylation pathways throughout the retinohypothalamic tract terminals and links between the transcription factor Rev-Erbα and Fbxl3. Conclusions The results of this study, primarily represent a contribution towards an understanding of electrophysiological and molecular phenotypic responses to external stimuli in the Afh model. Moreover, as DNA methylation has recently emerged as a new regulator of neuronal networks with important consequences for circadian behaviour, we discuss the impact of the Afh mutation on the epigenetic landscape of circadian biology.
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Affiliation(s)
- Federico Tinarelli
- Genetics and Epigenetics of Behaviour (GEB) Laboratory, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy.,BioMed X Innovation Center, Im Neuenheimer Feld 515, 69120, Heidelberg, Germany
| | - Elena Ivanova
- Epigenetics Programme, The Babraham Institute, Cambridge, UK
| | - Ilaria Colombi
- Neuroscience and Brain Technologies, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy.,Brain Development and Disease, NBT, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy
| | - Erica Barini
- Neurodevelopmental and Neurodegenerative Disease Laboratory, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy.,AbbVie Deutschland GmbH & Co, Knollstr, 67061, Ludwigshafen, Germany
| | - Edoardo Balzani
- Genetics and Epigenetics of Behaviour (GEB) Laboratory, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy.,Center for Neural Science, New York University, New York, NY, 10006, USA
| | - Celina Garcia Garcia
- Genetics and Epigenetics of Behaviour (GEB) Laboratory, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy
| | - Laura Gasparini
- Neurodevelopmental and Neurodegenerative Disease Laboratory, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy.,AbbVie Deutschland GmbH & Co, Knollstr, 67061, Ludwigshafen, Germany
| | - Michela Chiappalone
- Neuroscience and Brain Technologies, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy.,Rehab Technologies, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy
| | - Gavin Kelsey
- Epigenetics Programme, The Babraham Institute, Cambridge, UK
| | - Valter Tucci
- Genetics and Epigenetics of Behaviour (GEB) Laboratory, Istituto Italiano Di Tecnologia, via Morego, 30, 16163, Genova, Italy.
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19
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Seasonality and light phase-resetting in the mammalian circadian rhythm. Sci Rep 2020; 10:19506. [PMID: 33177530 PMCID: PMC7658258 DOI: 10.1038/s41598-020-74002-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/18/2020] [Indexed: 11/13/2022] Open
Abstract
We study the impact of light on the mammalian circadian system using the theory of phase response curves. Using a recently developed ansatz we derive a low-dimensional macroscopic model for the core circadian clock in mammals. Significantly, the variables and parameters in our model have physiological interpretations and may be compared with experimental results. We focus on the effect of four key factors which help shape the mammalian phase response to light: heterogeneity in the population of oscillators, the structure of the typical light phase response curve, the fraction of oscillators which receive direct light input and changes in the coupling strengths associated with seasonal day-lengths. We find these factors can explain several experimental results and provide insight into the processing of light information in the mammalian circadian system. In particular, we find that the sensitivity of the circadian system to light may be modulated by changes in the relative coupling forces between the light sensing and non-sensing populations. Finally, we show how seasonal day-length, after-effects to light entrainment and seasonal variations in light sensitivity in the mammalian circadian clock are interrelated.
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20
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Circadian VIPergic Neurons of the Suprachiasmatic Nuclei Sculpt the Sleep-Wake Cycle. Neuron 2020; 108:486-499.e5. [PMID: 32916091 PMCID: PMC7803671 DOI: 10.1016/j.neuron.2020.08.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 10/07/2019] [Accepted: 07/31/2020] [Indexed: 01/08/2023]
Abstract
Although the mammalian rest-activity cycle is controlled by a "master clock" in the suprachiasmatic nucleus (SCN) of the hypothalamus, it is unclear how firing of individual SCN neurons gates individual features of daily activity. Here, we demonstrate that a specific transcriptomically identified population of mouse VIP+ SCN neurons is active at the "wrong" time of day-nighttime-when most SCN neurons are silent. Using chemogenetic and optogenetic strategies, we show that these neurons and their cellular clocks are necessary and sufficient to gate and time nighttime sleep but have no effect upon daytime sleep. We propose that mouse nighttime sleep, analogous to the human siesta, is a "hard-wired" property gated by specific neurons of the master clock to favor subsequent alertness prior to dawn (a circadian "wake maintenance zone"). Thus, the SCN is not simply a 24-h metronome: specific populations sculpt critical features of the sleep-wake cycle.
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21
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Circadian disruption impairs fear extinction and memory of conditioned safety in mice. Behav Brain Res 2020; 393:112788. [DOI: 10.1016/j.bbr.2020.112788] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/21/2020] [Accepted: 06/22/2020] [Indexed: 02/06/2023]
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22
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Kim KY, Rios LC, Le H, Perez AJ, Phan S, Bushong EA, Deerinck TJ, Liu YH, Ellisman MA, Lev-Ram V, Ju S, Panda SA, Yoon S, Hirayama M, Mure LS, Hatori M, Ellisman MH, Panda S. Synaptic Specializations of Melanopsin-Retinal Ganglion Cells in Multiple Brain Regions Revealed by Genetic Label for Light and Electron Microscopy. Cell Rep 2020; 29:628-644.e6. [PMID: 31618632 DOI: 10.1016/j.celrep.2019.09.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 07/01/2019] [Accepted: 09/04/2019] [Indexed: 11/17/2022] Open
Abstract
The form and synaptic fine structure of melanopsin-expressing retinal ganglion cells, also called intrinsically photosensitive retinal ganglion cells (ipRGCs), were determined using a new membrane-targeted version of a genetic probe for correlated light and electron microscopy (CLEM). ipRGCs project to multiple brain regions, and because the method labels the entire neuron, it was possible to analyze nerve terminals in multiple retinorecipient brain regions, including the suprachiasmatic nucleus (SCN), olivary pretectal nucleus (OPN), and subregions of the lateral geniculate. Although ipRGCs provide the only direct retinal input to the OPN and SCN, ipRGC terminal arbors and boutons were found to be remarkably different in each target region. A network of dendro-dendritic chemical synapses (DDCSs) was also revealed in the SCN, with ipRGC axon terminals preferentially synapsing on the DDCS-linked cells. The methods developed to enable this analysis should propel other CLEM studies of long-distance brain circuits at high resolution.
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Affiliation(s)
- Keun-Young Kim
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Luis C Rios
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Hiep Le
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Alex J Perez
- National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Sébastien Phan
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Eric A Bushong
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Thomas J Deerinck
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Yu Hsin Liu
- Salk Institute for Biological Studies, La Jolla, CA, USA; Medical Scientist Training Program, University of California at San Diego School of Medicine, La Jolla, CA, USA
| | - Maya A Ellisman
- Biological Sciences Graduate Training Program, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Varda Lev-Ram
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Suyeon Ju
- National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Sneha A Panda
- National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Sanghee Yoon
- National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | | | - Ludovic S Mure
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Megumi Hatori
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Mark H Ellisman
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA; Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA.
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23
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Hozer C, Pifferi F. Physiological and cognitive consequences of a daily 26 h photoperiod in a primate : exploring the underlying mechanisms of the circadian resonance theory. Proc Biol Sci 2020; 287:20201079. [PMID: 32693726 PMCID: PMC7423648 DOI: 10.1098/rspb.2020.1079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 06/26/2020] [Indexed: 12/18/2022] Open
Abstract
The biological clock expresses circadian rhythms, whose endogenous period (tau) is close to 24 h. Daily resetting of the circadian clock to the 24 h natural photoperiod might induce marginal costs that would accumulate over time and forward affect fitness. It was proposed as the circadian resonance theory. For the first time, we aimed to evaluate these physiological and cognitive costs that would partially explain the mechanisms of the circadian resonance hypothesis. We evaluated the potential costs of imposing a 26 h photoperiodic regimen compared to the classical 24 h entrainment measuring several physiological and cognitive parameters (body temperature, energetic expenditure, oxidative stress, cognitive performances) in males of a non-human primate (Microcebus murinus), a nocturnal species whose endogenous period is about 23.5 h. We found significant higher resting body temperature and energy expenditure and lower cognitive performances when the photoperiodic cycle length was 26 h. Together these results suggest that a great deviation of external cycles from tau leads to daily greater energetic expenditure, and lower cognitive capacities. To our knowledge, this study is the first to highlight potential mechanisms of circadian resonance theory.
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Affiliation(s)
| | - Fabien Pifferi
- UMR CNRS MNHN 7179 MECADEV, 1 Avenue du Petit Château 91800 Brunoy, France
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24
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Tackenberg MC, Hughey JJ, McMahon DG. Distinct Components of Photoperiodic Light Are Differentially Encoded by the Mammalian Circadian Clock. J Biol Rhythms 2020; 35:353-367. [PMID: 32527181 DOI: 10.1177/0748730420929217] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Seasonal light cycles influence multiple physiological functions and are mediated through photoperiodic encoding by the circadian system. Despite our knowledge of the strong connection between seasonal light input and downstream circadian changes, less is known about the specific components of seasonal light cycles that are encoded and induce persistent changes in the circadian system. Using combinations of 3 T cycles (23, 24, 26 h) and 2 photoperiods per T cycle (long and short, with duty cycles scaled to each T cycle), we investigate the after-effects of entrainment to these 6 light cycles. We measure locomotor behavior duration (α), period (τ), and entrained phase angle (ψ) in vivo and SCN phase distribution (σφ), τ, and ψ ex vivo to refine our understanding of critical light components for influencing particular circadian properties. We find that both photoperiod and T-cycle length drive determination of in vivo ψ but differentially influence after-effects in α and τ, with photoperiod driving changes in α and photoperiod length and T-cycle length combining to influence τ. Using skeleton photoperiods, we demonstrate that in vivo ψ is determined by both parametric and nonparametric components, while changes in α are driven nonparametrically. Within the ex vivo SCN, we find that ψ and σφ of the PER2∷LUCIFERASE rhythm follow closely with their likely behavioral counterparts (ψ and α of the locomotor activity rhythm) while also confirming previous reports of τ after-effects of gene expression rhythms showing negative correlations with behavioral τ after-effects in response to T cycles. We demonstrate that within-SCN σφ changes, thought to underlie α changes in vivo, are induced primarily nonparametrically. Taken together, our results demonstrate that distinct components of seasonal light input differentially influence ψ, α, and τ and suggest the possibility of separate mechanisms driving the persistent changes in circadian behaviors mediated by seasonal light.
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Affiliation(s)
| | - Jacob J Hughey
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee.,Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Douglas G McMahon
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee.,Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee
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25
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26
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Dahl CD, Ferrando E, Zuberbühler K. An information-theory approach to geometry for animal groups. Anim Cogn 2020; 23:807-817. [PMID: 32385570 DOI: 10.1007/s10071-020-01374-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 03/12/2020] [Accepted: 03/21/2020] [Indexed: 12/30/2022]
Abstract
One of the hardest problems in studying animal behaviour is to quantify patterns of social interaction at the group level. Recent technological developments in global positioning system (GPS) devices have opened up new avenues for locating animals with unprecedented spatial and temporal resolution. Likewise, advances in computing power have enabled new levels of data analyses with complex mathematical models to address unresolved problems in animal behaviour, such as the nature of group geometry and the impact of group-level interactions on individuals. Here, we present an information theory-based tool for the analysis of group behaviour. We illustrate its affordances with GPS data collected from a freely interacting pack of 15 Siberian huskies (Canis lupus familiaris). We found that individual freedom in movement decisions was limited to about 4%, while a subject's location could be predicted with 96% median accuracy by the locations of other group members. Dominant individuals were less affected by other individuals' locations than subordinate ones, and same-sex individuals influenced each other more strongly than opposite-sex individuals. We also found that kinship relationships increased the mutual dependencies of individuals. Moreover, the network stability of the pack deteriorated with an upcoming feeding event. Together, we conclude that information theory-based approaches, coupled with state-of-the-art bio-logging technology, provide a powerful tool for future studies of animal social interactions beyond the dyadic level.
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Affiliation(s)
- Christoph D Dahl
- Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, Taipei, Taiwan. .,Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, New Taipei City, Taiwan. .,Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
| | - Elodie Ferrando
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Klaus Zuberbühler
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.,School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
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27
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Schmal C, Herzel H, Myung J. Clocks in the Wild: Entrainment to Natural Light. Front Physiol 2020; 11:272. [PMID: 32300307 PMCID: PMC7142224 DOI: 10.3389/fphys.2020.00272] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 03/09/2020] [Indexed: 01/09/2023] Open
Abstract
Entrainment denotes a process of coordinating the internal circadian clock to external rhythmic time-cues (Zeitgeber), mainly light. It is facilitated by stronger Zeitgeber signals and smaller period differences between the internal clock and the external Zeitgeber. The phase of entrainment ψ is a result of this process on the side of the circadian clock. On Earth, the period of the day-night cycle is fixed to 24 h, while the periods of circadian clocks distribute widely due to natural variation within and between species. The strength and duration of light depend locally on season and geographic latitude. Therefore, entrainment characteristics of a circadian clock vary under a local light environment and distribute along geoecological settings. Using conceptual models of circadian clocks, we investigate how local conditions of natural light shape global patterning of entrainment through seasons. This clock-side entrainment paradigm enables us to predict systematic changes in the global distribution of chronotypes.
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Affiliation(s)
- Christoph Schmal
- Department of Biology, Faculty of Life Sciences, Institute for Theoretical Biology, Humboldt Universität zu Berlin, Berlin, Germany
| | - Hanspeter Herzel
- Department Basic Sciences, Institute for Theoretical Biology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jihwan Myung
- Graduate Institute of Mind, Brain, and Consciousness, Taipei Medical University, Taipei, Taiwan.,Brain and Consciousness Research Centre, Taipei Medical University-Shuang Ho Hospital, Ministry of Health and Welfare, New Taipei City, Taiwan.,Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.,Computational Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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28
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Coyle CS, Caso F, Tolla E, Barrett P, Onishi KG, Tello JA, Stevenson TJ. Ovarian hormones induce de novo DNA methyltransferase expression in the Siberian hamster suprachiasmatic nucleus. J Neuroendocrinol 2020; 32:e12819. [PMID: 31800973 DOI: 10.1111/jne.12819] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 10/30/2019] [Accepted: 12/02/2019] [Indexed: 01/11/2023]
Abstract
The present study investigated neuroanatomically localised changes in de novo DNA methyltransferase expression in the female Siberian hamster (Phodopus sungorus). The objectives were to identify the neuroendocrine substrates that exhibit rhythmic Dnmt3a and Dnmt3b expression across the oestrous cycle and also examine the role of ovarian steroids. Hypothalamic Dnmt3a expression was observed to significantly increase during the transition from pro-oestrous to oestrous. A single bolus injection of diethylstilbestrol and progesterone was sufficient to increase Dnmt3a cell numbers and Dnmt3b immunoreactive intensity in the suprachiasmatic nucleus. In vitro analyses using an embryonic rodent cell line revealed that diethylstilbestrol was sufficient to induce Dnmt3b expression. Up-regulating DNA methylation in vitro reduced the expression of vasoactive intestinal polypeptide, Vip, and the circadian clock gene, Bmal1. Together, these data indicate that ovarian steroids drive de novo DNA methyltransferase expression in the mammalian suprachiasmatic nucleus and increased methylation may regulate genes involved in the circadian timing of oestrous: Vip and Bmal1. Overall, epigenetically mediated neuroendocrine reproductive events may reflect an evolutionarily ancient process involved in the timing of female fertility.
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Affiliation(s)
- Chris S Coyle
- Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Federico Caso
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Elisabetta Tolla
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Perry Barrett
- Rowett Institute, University of Aberdeen, Aberdeen, UK
| | - Kenneth G Onishi
- Department of Psychology, Institute for Mind and Biology, University of Chicago, Chicago, IL, USA
| | - Javier A Tello
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Tyler John Stevenson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
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29
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MacKay H, Scott CA, Duryea JD, Baker MS, Laritsky E, Elson AE, Garland T, Fiorotto ML, Chen R, Li Y, Coarfa C, Simerly RB, Waterland RA. DNA methylation in AgRP neurons regulates voluntary exercise behavior in mice. Nat Commun 2019; 10:5364. [PMID: 31792207 PMCID: PMC6889160 DOI: 10.1038/s41467-019-13339-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 10/16/2019] [Indexed: 12/16/2022] Open
Abstract
DNA methylation regulates cell type-specific gene expression. Here, in a transgenic mouse model, we show that deletion of the gene encoding DNA methyltransferase Dnmt3a in hypothalamic AgRP neurons causes a sedentary phenotype characterized by reduced voluntary exercise and increased adiposity. Whole-genome bisulfite sequencing (WGBS) and transcriptional profiling in neuronal nuclei from the arcuate nucleus of the hypothalamus (ARH) reveal differentially methylated genomic regions and reduced expression of AgRP neuron-associated genes in knockout mice. We use read-level analysis of WGBS data to infer putative ARH neural cell types affected by the knockout, and to localize promoter hypomethylation and increased expression of the growth factor Bmp7 to AgRP neurons, suggesting a role for aberrant TGF-β signaling in the development of this phenotype. Together, these data demonstrate that DNA methylation in AgRP neurons is required for their normal epigenetic development and neuron-specific gene expression profiles, and regulates voluntary exercise behavior. AgRP neurons in the hypothalamic arcuate nucleus (ARH) are involved in regulating hunger and energy balance. Here the authors show that knockout of the DNA methyltransferase Dnmt3a in AgRP neurons of the ARH leads to a reduction in voluntary exercise along with numerous epigenetic and gene expression changes in ARH neurons.
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Affiliation(s)
- Harry MacKay
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, Houston, TX, 77030, USA
| | - C Anthony Scott
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, Houston, TX, 77030, USA
| | - Jack D Duryea
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, Houston, TX, 77030, USA
| | - Maria S Baker
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, Houston, TX, 77030, USA
| | - Eleonora Laritsky
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, Houston, TX, 77030, USA
| | - Amanda E Elson
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN, 37235, USA
| | - Theodore Garland
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, 92521, USA
| | - Marta L Fiorotto
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, Houston, TX, 77030, USA.,Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Rui Chen
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Yumei Li
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Cristian Coarfa
- Department of Molecular & Cell Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Richard B Simerly
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN, 37235, USA
| | - Robert A Waterland
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, Houston, TX, 77030, USA. .,Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
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30
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Rohr KE, Pancholi H, Haider S, Karow C, Modert D, Raddatz NJ, Evans J. Seasonal plasticity in GABA A signaling is necessary for restoring phase synchrony in the master circadian clock network. eLife 2019; 8:49578. [PMID: 31746738 PMCID: PMC6867713 DOI: 10.7554/elife.49578] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 10/15/2019] [Indexed: 12/14/2022] Open
Abstract
Annual changes in the environment threaten survival, and numerous biological processes in mammals adjust to this challenge via seasonal encoding by the suprachiasmatic nucleus (SCN). To tune behavior according to day length, SCN neurons display unified rhythms with synchronous phasing when days are short, but will divide into two sub-clusters when days are long. The transition between SCN states is critical for maintaining behavioral responses to seasonal change, but the mechanisms regulating this form of neuroplasticity remain unclear. Here we identify that a switch in chloride transport and GABAA signaling is critical for maintaining state plasticity in the SCN network. Further, we reveal that blocking excitatory GABAA signaling locks the SCN into its long day state. Collectively, these data demonstrate that plasticity in GABAA signaling dictates how clock neurons interact to maintain environmental encoding. Further, this work highlights factors that may influence susceptibility to seasonal disorders in humans. In winter, as the days become shorter, millions of people find that their mood and energy levels start to drop. They crave carbohydrates, struggle with their weight, and find it harder to get out of bed in the mornings. These individuals are suffering from the ‘winter blues’ or seasonal affective disorder (SAD), and most find that their symptoms spontaneously improve in the spring when the days become longer again. Many also benefit from bright light therapy during the winter months, but not everyone responds fully to this treatment, so additional options are needed. The winter blues occur when the brain adjusts to changes in day length with the onset of winter. The brain region responsible for making this adjustment is the suprachiasmatic nucleus (SCN). The SCN is the master clock of the brain that coordinates the body’s circadian rhythms – the daily fluctuations in things like appetite, body temperature, sleep and wakefulness. But as well as being the brain’s clock, the SCN is also the brain’s calendar. In winter, when the days are short, SCN neurons coordinate their activity and fire in synchrony. But in summer, when the days are long, SCN neurons divide into two clusters, which fire at different times. By transitioning between these two states, the SCN helps the body adjust to seasonal changes in day length. Rohr, Pancholi et al. now provide new insight into the mechanism behind this process by showing that light alters the neurochemistry of the SCN. Exposing mice to long days causes a brain chemical called GABA to switch from inhibiting neurons in the SCN to activating them. Blocking this switch from inhibition to activation locks the SCN into its 'summer state'. Rohr, Pancholi et al. propose that this failure to transition to the winter state may be an interesting way to prevent the winter blues. While much remains to be learned about this process, these findings pave the way for better understanding the neurobiology of winter depression and how best to treat it.
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Affiliation(s)
- Kayla E Rohr
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Harshida Pancholi
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Shabi Haider
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Christopher Karow
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - David Modert
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Nicholas J Raddatz
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Jennifer Evans
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
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31
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Andreeva–Gateva PA, Mihaleva ID, Dimova II. Type 2 diabetes mellitus and cardiovascular risk; what the pharmacotherapy can change through the epigenetics. Postgrad Med 2019; 132:109-125. [DOI: 10.1080/00325481.2019.1681215] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Pavlina A. Andreeva–Gateva
- Department of Pharmacology and Toxicology, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria
- Department of Pharmacology, Medical Faculty, Sofia University “St Kliment Ohridski”, Sofia, Bulgaria
| | - Ivelina D. Mihaleva
- Department of Pharmacology and Toxicology, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria
| | - Ivanka I. Dimova
- Department of Medical Genetics, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria
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32
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Foster S, Christiansen T, Antle MC. Modeling the Influence of Synaptic Plasticity on After-effects. J Biol Rhythms 2019; 34:645-657. [PMID: 31436125 DOI: 10.1177/0748730419871189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
While circadian rhythms in physiology and behavior demonstrate remarkable day-to-day precision, they are also able to exhibit plasticity in a variety of parameters and under a variety of conditions. After-effects are one type of plasticity in which exposure to non-24-h light-dark cycles (T-cycles) will alter the animal's free-running rhythm in subsequent constant conditions. We use a mathematical model to explore whether the concept of synaptic plasticity can explain the observation of after-effects. In this model, the SCN is composed of a set of individual oscillators randomly selected from a normally distributed population. Each cell receives input from a defined set of oscillators, and the overall period of a cell is a weighted average of its own period and that of its inputs. The influence that an input has on its target's period is determined by the proximity of the input cell's period to the imposed T-cycle period, such that cells with periods near T will have greater influence. Such an arrangement is able to duplicate the phenomenon of after-effects, with relatively few inputs per cell (~4-5) being required. When the variability of periods between oscillators is low, the system is quite robust and results in minimal after-effects, while systems with greater between-cell variability exhibit greater magnitude after-effects. T-cycles that produce maximal after-effects have periods within ~2.5 to 3 h of the population period. Overall, this model demonstrates that synaptic plasticity in the SCN network could contribute to plasticity of the circadian period.
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Affiliation(s)
- Semra Foster
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Tom Christiansen
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Michael C Antle
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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33
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Abstract
The suprachiasmatic nucleus (SCN) of the hypothalamus is remarkable. Despite numbering only about 10,000 neurons on each side of the third ventricle, the SCN is our principal circadian clock, directing the daily cycles of behaviour and physiology that set the tempo of our lives. When this nucleus is isolated in organotypic culture, its autonomous timing mechanism can persist indefinitely, with precision and robustness. The discovery of the cell-autonomous transcriptional and post-translational feedback loops that drive circadian activity in the SCN provided a powerful exemplar of the genetic specification of complex mammalian behaviours. However, the analysis of circadian time-keeping is moving beyond single cells. Technical and conceptual advances, including intersectional genetics, multidimensional imaging and network theory, are beginning to uncover the circuit-level mechanisms and emergent properties that make the SCN a uniquely precise and robust clock. However, much remains unknown about the SCN, not least the intrinsic properties of SCN neurons, its circuit topology and the neuronal computations that these circuits support. Moreover, the convention that the SCN is a neuronal clock has been overturned by the discovery that astrocytes are an integral part of the timepiece. As a test bed for examining the relationships between genes, cells and circuits in sculpting complex behaviours, the SCN continues to offer powerful lessons and opportunities for contemporary neuroscience.
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34
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Bullock B. An Interdisciplinary Perspective on the Association Between Chronotype and Well-being. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:359-364. [PMID: 31249496 PMCID: PMC6585516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Individuals with a circadian preference for mental and physical activity later in the day ("Evening types") are consistently found to fare worse on most facets of well-being than individuals with a circadian preference for mental and physical activity earlier in the day ("Morning types"). Several explanatory hypotheses of this association between chronotype and well-being have been proposed, including shared genetic, biological, developmental, and psychosocial mechanisms. This paper presents a critical summary of these explanatory mechanisms and offers suggestions for their integration in an interdisciplinary biopsychosocial framework.
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Affiliation(s)
- Ben Bullock
- To whom all correspondence should be addressed: Ben Bullock, Swinburne University of Technology, PO Box 218, Mail No. H99, Hawthorn, Victoria, Australia; Tel: +61 3 9214 4358,
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35
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Pacheco-Bernal I, Becerril-Pérez F, Aguilar-Arnal L. Circadian rhythms in the three-dimensional genome: implications of chromatin interactions for cyclic transcription. Clin Epigenetics 2019; 11:79. [PMID: 31092281 PMCID: PMC6521413 DOI: 10.1186/s13148-019-0677-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 04/29/2019] [Indexed: 12/20/2022] Open
Abstract
Circadian rhythms orchestrate crucial physiological functions and behavioral aspects around a day in almost all living forms. The circadian clock is a time tracking system that permits organisms to predict and anticipate periodic environmental fluctuations. The circadian system is hierarchically organized, and a master pacemaker located in the brain synchronizes subsidiary clocks in the rest of the organism. Adequate synchrony between central and peripheral clocks ensures fitness and potentiates a healthy state. Conversely, disruption of circadian rhythmicity is associated with metabolic diseases, psychiatric disorders, or cancer, amongst other pathologies. Remarkably, the molecular machinery directing circadian rhythms consists of an intricate network of feedback loops in transcription and translation which impose 24-h cycles in gene expression across all tissues. Interestingly, the molecular clock collaborates with multitude of epigenetic remodelers to fine tune transcriptional rhythms in a tissue-specific manner. Very exciting research demonstrate that three-dimensional properties of the genome have a regulatory role on circadian transcriptional rhythmicity, from bacteria to mammals. Unexpectedly, highly dynamic long-range chromatin interactions have been revealed during the circadian cycle in mammalian cells, where thousands of regulatory elements physically interact with promoter regions every 24 h. Molecular mechanisms directing circadian dynamics on chromatin folding are emerging, and the coordinated action between the core clock and epigenetic remodelers appears to be essential for these movements. These evidences reveal a critical epigenetic regulatory layer for circadian rhythms and pave the way to uncover molecular mechanisms triggering pathological states associated to circadian misalignment.
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Affiliation(s)
- Ignacio Pacheco-Bernal
- Instituto de Investigaciones Biomédicas, Departamento de Biología Celular y Fisiología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Fernando Becerril-Pérez
- Instituto de Investigaciones Biomédicas, Departamento de Biología Celular y Fisiología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Lorena Aguilar-Arnal
- Instituto de Investigaciones Biomédicas, Departamento de Biología Celular y Fisiología, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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36
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Musashi‐2 and related stem cell proteins in the mouse suprachiasmatic nucleus and their potential role in circadian rhythms. Int J Dev Neurosci 2019; 75:44-58. [DOI: 10.1016/j.ijdevneu.2019.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 04/17/2019] [Accepted: 04/30/2019] [Indexed: 01/14/2023] Open
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37
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Chang AM, Duffy JF, Buxton OM, Lane JM, Aeschbach D, Anderson C, Bjonnes AC, Cain SW, Cohen DA, Frayling TM, Gooley JJ, Jones SE, Klerman EB, Lockley SW, Munch M, Rajaratnam SMW, Rueger M, Rutter MK, Santhi N, Scheuermaier K, Van Reen E, Weedon MN, Czeisler CA, Scheer FAJL, Saxena R. Chronotype Genetic Variant in PER2 is Associated with Intrinsic Circadian Period in Humans. Sci Rep 2019; 9:5350. [PMID: 30926824 PMCID: PMC6440993 DOI: 10.1038/s41598-019-41712-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 03/14/2019] [Indexed: 12/21/2022] Open
Abstract
The PERIOD2 (PER2) gene is a core molecular component of the circadian clock and plays an important role in the generation and maintenance of daily rhythms. Rs35333999, a missense variant of PER2 common in European populations, has been shown to associate with later chronotype. Chronotype relates to the timing of biological and behavioral activities, including when we sleep, eat, and exercise, and later chronotype is associated with longer intrinsic circadian period (cycle length), a fundamental property of the circadian system. Thus, we tested whether this PER2 variant was associated with circadian period and found significant associations with longer intrinsic circadian period as measured under forced desynchrony protocols, the 'gold standard' for intrinsic circadian period assessment. Minor allele (T) carriers exhibited significantly longer circadian periods when determinations were based on either core body temperature or plasma melatonin measurements, as compared to non-carriers (by 12 and 11 min, respectively; accounting for ~7% of inter-individual variance). These findings provide a possible underlying biological mechanism for inter-individual differences in chronotype, and support the central role of PER2 in the human circadian timing system.
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Affiliation(s)
- Anne-Marie Chang
- Department of Biobehavioral Health, Pennsylvania State University, University Park, Pennsylvania, 16802, USA.
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA.
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA.
- Medical and Population Genetics, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts, 02142, USA.
| | - Jeanne F Duffy
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Orfeu M Buxton
- Department of Biobehavioral Health, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Department of Social and Behavioral Sciences, Harvard Chan School of Public Health, Boston, Massachusetts, 02115, USA
| | - Jacqueline M Lane
- Medical and Population Genetics, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts, 02142, USA
- Department of Anesthesia, Critical Care and Pain Medicine and Center for Genomic Medicine; Massachusetts General Hospital, Boston, Massachusetts, 02114, USA
| | - Daniel Aeschbach
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Department of Sleep and Human Factors Research, Institute of Aerospace Medicine, German Aerospace Center, Cologne, 51147, Germany
| | - Clare Anderson
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Monash Institute of Cognitive and Clinical Neurosciences and School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Andrew C Bjonnes
- Medical and Population Genetics, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts, 02142, USA
- Department of Anesthesia, Critical Care and Pain Medicine and Center for Genomic Medicine; Massachusetts General Hospital, Boston, Massachusetts, 02114, USA
| | - Sean W Cain
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Monash Institute of Cognitive and Clinical Neurosciences and School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Daniel A Cohen
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Timothy M Frayling
- Genetics of Complex Traits, University of Exeter Medical School, Exeter, United Kingdom
| | - Joshua J Gooley
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Samuel E Jones
- Genetics of Complex Traits, University of Exeter Medical School, Exeter, United Kingdom
| | - Elizabeth B Klerman
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Steven W Lockley
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Mirjam Munch
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Sleep/Wake Research Centre, College of Health, Massey University, Wellington, New Zealand
| | - Shantha M W Rajaratnam
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Monash Institute of Cognitive and Clinical Neurosciences and School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Melanie Rueger
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Martin K Rutter
- Division of Endocrinology, Diabetes & Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Manchester Diabetes Centre, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - Nayantara Santhi
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Surrey Sleep Research Centre, University of Surrey, Guildford, UK
| | - Karine Scheuermaier
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Wits Sleep Laboratory, Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Eliza Van Reen
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI, USA
| | - Michael N Weedon
- Genetics of Complex Traits, University of Exeter Medical School, Exeter, United Kingdom
| | - Charles A Czeisler
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Frank A J L Scheer
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA.
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, 02115, USA.
| | - Richa Saxena
- Division of Sleep and Circadian Disorders, Department of Medicine and Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, 02115, USA
- Medical and Population Genetics, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts, 02142, USA
- Department of Anesthesia, Critical Care and Pain Medicine and Center for Genomic Medicine; Massachusetts General Hospital, Boston, Massachusetts, 02114, USA
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38
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Genomic imprinting and the control of sleep in mammals. Curr Opin Behav Sci 2019. [DOI: 10.1016/j.cobeha.2018.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Tokuda IT, Ono D, Honma S, Honma KI, Herzel H. Coherency of circadian rhythms in the SCN is governed by the interplay of two coupling factors. PLoS Comput Biol 2018; 14:e1006607. [PMID: 30532130 PMCID: PMC6301697 DOI: 10.1371/journal.pcbi.1006607] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 12/20/2018] [Accepted: 10/30/2018] [Indexed: 01/05/2023] Open
Abstract
Circadian clocks are autonomous oscillators driving daily rhythms in physiology and behavior. In mammals, a network of coupled neurons in the suprachiasmatic nucleus (SCN) is entrained to environmental light-dark cycles and orchestrates the timing of peripheral organs. In each neuron, transcriptional feedbacks generate noisy oscillations. Coupling mediated by neuropeptides such as VIP and AVP lends precision and robustness to circadian rhythms. The detailed coupling mechanisms between SCN neurons are debated. We analyze organotypic SCN slices from neonatal and adult mice in wild-type and multiple knockout conditions. Different degrees of rhythmicity are quantified by pixel-level analysis of bioluminescence data. We use empirical orthogonal functions (EOFs) to characterize spatio-temporal patterns. Simulations of coupled stochastic single cell oscillators can reproduce the diversity of observed patterns. Our combination of data analysis and modeling provides deeper insight into the enormous complexity of the data: (1) Neonatal slices are typically stronger oscillators than adult slices pointing to developmental changes of coupling. (2) Wild-type slices are completely synchronized and exhibit specific spatio-temporal patterns of phases. (3) Some slices of Cry double knockouts obey impaired synchrony that can lead to co–existing rhythms (“splitting”). (4) The loss of VIP-coupling leads to desynchronized rhythms with few residual local clusters. Additional information was extracted from co–culturing slices with rhythmic neonatal wild-type SCNs. These co–culturing experiments were simulated using external forcing terms representing VIP and AVP signaling. The rescue of rhythmicity via co–culturing lead to surprising results, since a cocktail of AVP-antagonists improved synchrony. Our modeling suggests that these counter-intuitive observations are pointing to an antagonistic action of VIP and AVP coupling. Our systematic theoretical and experimental study shows that dual coupling mechanisms can explain the astonishing complexity of spatio-temporal patterns in SCN slices. The mammalian circadian clock is orchestrated by a network of coupled neurons. Brain slice preparations allow the analysis of coupling mechanisms mediated by neuropeptides. From bioluminescence recordings, we extract single cell characteristics such as period, amplitude and damping rate. Our data-based stochastic network model involves local coupling between cells and additional external forcing. Available experimental data guide our simulations with two distinct coupling and forcing mechanisms representing the neuropeptides VIP and AVP. We compare our simulations with experiments from neonatal and adult wild-type brain slices and multiple knockouts. Furthermore, we study co–culturing of slices with synchronized neonatal wild-type slices. The extreme complexity of the spatio-temporal patterns is quantified using empirical orthogonal functions (EOFs). The experimental reduction of AVP coupling leads to surprising observations. In double knockouts, inhibition of AVP signaling can improve synchrony, whereas, in triple knockouts, coherency is reduced. Our network modeling shows that these counter-intuitive observations can be explained by an antagonistic action of VIP and AVP signaling. The agreement of experiments and simulations suggests that quite complex spatio-temporal patterns can appear as emergent properties of oscillator networks with dual coupling mechanisms.
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Affiliation(s)
- Isao T. Tokuda
- Department of Mechanical Engineering, Ritsumeikan University, Shiga, Japan
- * E-mail: (ITT); (HH)
| | - Daisuke Ono
- Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Sato Honma
- Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Ken-Ichi Honma
- Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hanspeter Herzel
- Institute for Theoretical Biology, Charité and Humboldt University of Berlin, Berlin, Germany
- * E-mail: (ITT); (HH)
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40
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Collins B, Brown SA. Beyond the molecular clock. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2018.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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41
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Olde Engberink AHO, Meijer JH, Michel S. Chloride cotransporter KCC2 is essential for GABAergic inhibition in the SCN. Neuropharmacology 2018; 138:80-86. [PMID: 29782876 DOI: 10.1016/j.neuropharm.2018.05.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 04/26/2018] [Accepted: 05/17/2018] [Indexed: 12/31/2022]
Abstract
One of the principal neurotransmitters of the central nervous system is GABA. In the adult brain, GABA is predominantly inhibitory, but there is growing evidence indicating that GABA can shift to excitatory action depending on environmental conditions. In the mammalian central circadian clock of the suprachiasmatic nucleus (SCN) GABAergic activity shifts from inhibition to excitation when animals are exposed to long day photoperiod. The polarity of the GABAergic response (inhibitory versus excitatory) depends on the GABA equilibrium potential determined by the intracellular Cl- concentration ([Cl-]i). Chloride homeostasis can be regulated by Cl- cotransporters like NKCC1 and KCC2 in the membrane, but the mechanisms for maintaining [Cl-]i are still under debate. This study investigates the role of KCC2 on GABA-induced Ca2+ transients in SCN neurons from mice exposed to different photoperiods. We show for the first time that blocking KCC2 with the newly developed blocker ML077 can cause a shift in the polarity of the GABAergic response. This will increase the amount of excitatory responses in SCN neurons and thus cause a shift in excitatory/inhibitory ratio. These results indicate that KCC2 is an essential component in regulating [Cl-]i and the equilibrium potential of Cl- and thereby determining the sign of the GABAergic response. Moreover, our data suggest a role for the Cl- cotransporters in the switch from inhibition to excitation observed under long day photoperiod.
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Affiliation(s)
- A H O Olde Engberink
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, the Netherlands
| | - J H Meijer
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, the Netherlands
| | - S Michel
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, the Netherlands.
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42
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A Meta-Analysis Characterizing Stem-Like Gene Expression in the Suprachiasmatic Nucleus and Its Circadian Clock. BIOMED RESEARCH INTERNATIONAL 2018; 2018:3610603. [PMID: 30046594 PMCID: PMC6038684 DOI: 10.1155/2018/3610603] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 04/24/2018] [Accepted: 05/28/2018] [Indexed: 12/17/2022]
Abstract
Cells expressing proteins characteristic of stem cells and progenitor cells are present in the suprachiasmatic nucleus (SCN) of the adult mammalian hypothalamus. Any relationship between this distinctive feature and the master circadian clock of the SCN is unclear. Considering the lack of obvious neurogenesis in the adult SCN relative to the hippocampus and other structures that provide neurons and glia, it is possible that the SCN has partially differentiated cells that can provide neural circuit plasticity rather than ongoing neurogenesis. To test this possibility, available databases and publications were explored to identify highly expressed genes in the mouse SCN that also have known or suspected roles in cell differentiation, maintenance of stem-like states, or cell-cell interactions found in adult and embryonic stem cells and cancer stem cells. The SCN was found to have numerous genes associated with stem cell maintenance and increased motility from which we selected 25 of the most relevant genes. Over ninety percent of these stem-like genes were expressed at higher levels in the SCN than in other brain areas. Further analysis of this gene set could provide a greater understanding of how adjustments in cell contacts alter period and phase relationships of circadian rhythms. Circadian timing and its role in cancer, sleep, and metabolic disorders are likely influenced by genes selected in this study.
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Pett JP, Kondoff M, Bordyugov G, Kramer A, Herzel H. Co-existing feedback loops generate tissue-specific circadian rhythms. Life Sci Alliance 2018; 1:e201800078. [PMID: 30456356 PMCID: PMC6238625 DOI: 10.26508/lsa.201800078] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/01/2018] [Accepted: 06/04/2018] [Indexed: 12/04/2022] Open
Abstract
The analysis of tissue-specific data-based models of the gene regulatory network of the mammalian circadian clock reveals organ-specific synergies of feedback loops. Gene regulatory feedback loops generate autonomous circadian rhythms in mammalian tissues. The well-studied core clock network contains many negative and positive regulations. Multiple feedback loops have been discussed as primary rhythm generators but the design principles of the core clock and differences between tissues are still under debate. Here we use global optimization techniques to fit mathematical models to circadian gene expression profiles for different mammalian tissues. It turns out that for every investigated tissue multiple model parameter sets reproduce the experimental data. We extract for all model versions the most essential feedback loops and find auto-inhibitions of period and cryptochrome genes, Bmal1–Rev-erb-α loops, and repressilator motifs as possible rhythm generators. Interestingly, the essential feedback loops differ between tissues, pointing to specific design principles within the hierarchy of mammalian tissue clocks. Self-inhibitions of Per and Cry genes are characteristic for models of suprachiasmatic nucleus clocks, whereas in liver models many loops act in synergy and are connected by a repressilator motif. Tissue-specific use of a network of co-existing synergistic feedback loops could account for functional differences between organs.
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Affiliation(s)
- J Patrick Pett
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Matthew Kondoff
- Institute for Theoretical Biology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Grigory Bordyugov
- Institute for Theoretical Biology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Achim Kramer
- Laboratory of Chronobiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Hanspeter Herzel
- Institute for Theoretical Biology, Charité-Universitätsmedizin Berlin, Berlin, Germany
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44
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Schmal C, Myung J, Herzel H, Bordyugov G. Moran's I quantifies spatio-temporal pattern formation in neural imaging data. Bioinformatics 2018; 33:3072-3079. [PMID: 28575207 PMCID: PMC5870747 DOI: 10.1093/bioinformatics/btx351] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 05/30/2017] [Indexed: 12/20/2022] Open
Abstract
Motivation Neural activities of the brain occur through the formation of spatio-temporal patterns. In recent years, macroscopic neural imaging techniques have produced a large body of data on these patterned activities, yet a numerical measure of spatio-temporal coherence has often been reduced to the global order parameter, which does not uncover the degree of spatial correlation. Here, we propose to use the spatial autocorrelation measure Moran’s I, which can be applied to capture dynamic signatures of spatial organization. We demonstrate the application of this technique to collective cellular circadian clock activities measured in the small network of the suprachiasmatic nucleus (SCN) in the hypothalamus. Results We found that Moran’s I is a practical quantitative measure of the degree of spatial coherence in neural imaging data. Initially developed with a geographical context in mind, Moran’s I accounts for the spatial organization of any interacting units. Moran’s I can be modified in accordance with the characteristic length scale of a neural activity pattern. It allows a quantification of statistical significance levels for the observed patterns. We describe the technique applied to synthetic datasets and various experimental imaging time-series from cultured SCN explants. It is demonstrated that major characteristics of the collective state can be described by Moran’s I and the traditional Kuramoto order parameter R in a complementary fashion. Availability and implementation Python 2.7 code of illustrative examples can be found in the Supplementary Material. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Christoph Schmal
- Institute for Theoretical Biology, Charité Universitätsmedizin and Humboldt Universität, Berlin D-10115, Germany
| | - Jihwan Myung
- Institute for Theoretical Biology, Charité Universitätsmedizin and Humboldt Universität, Berlin D-10115, Germany.,Wissenschaftskolleg zu Berlin, Berlin D-14193, Germany.,Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Okinawa 904-0495, Japan
| | - Hanspeter Herzel
- Institute for Theoretical Biology, Charité Universitätsmedizin and Humboldt Universität, Berlin D-10115, Germany
| | - Grigory Bordyugov
- Institute for Theoretical Biology, Charité Universitätsmedizin and Humboldt Universität, Berlin D-10115, Germany
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Abstract
Mammalian circadian clocks have a hierarchical organization, governed by the suprachiasmatic nucleus (SCN) in the hypothalamus. The brain itself contains multiple loci that maintain autonomous circadian rhythmicity, but the contribution of the non-SCN clocks to this hierarchy remains unclear. We examine circadian oscillations of clock gene expression in various brain loci and discovered that in mouse, robust, higher amplitude, relatively faster oscillations occur in the choroid plexus (CP) compared to the SCN. Our computational analysis and modeling show that the CP achieves these properties by synchronization of “twist” circadian oscillators via gap-junctional connections. Using an in vitro tissue coculture model and in vivo targeted deletion of the Bmal1 gene to silence the CP circadian clock, we demonstrate that the CP clock adjusts the SCN clock likely via circulation of cerebrospinal fluid, thus finely tuning behavioral circadian rhythms. The suprachiasmatic nucleus (SCN) has been thought of as the master circadian clock, but peripheral circadian clocks do exist. Here, the authors show that the choroid plexus displays oscillations more robust than the SCN and that can be described as a Poincaré oscillator with negative twist.
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46
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Jörg DJ, Morelli LG, Jülicher F. Chemical event chain model of coupled genetic oscillators. Phys Rev E 2018; 97:032409. [PMID: 29776186 DOI: 10.1103/physreve.97.032409] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Indexed: 06/08/2023]
Abstract
We introduce a stochastic model of coupled genetic oscillators in which chains of chemical events involved in gene regulation and expression are represented as sequences of Poisson processes. We characterize steady states by their frequency, their quality factor, and their synchrony by the oscillator cross correlation. The steady state is determined by coupling and exhibits stochastic transitions between different modes. The interplay of stochasticity and nonlinearity leads to isolated regions in parameter space in which the coupled system works best as a biological pacemaker. Key features of the stochastic oscillations can be captured by an effective model for phase oscillators that are coupled by signals with distributed delays.
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Affiliation(s)
- David J Jörg
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany
| | - Luis G Morelli
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET-Partner Institute of the Max Planck Society, Polo Científico Tecnológico, Godoy Cruz 2390, C1425FQD, Buenos Aires, Argentina
- Departamento de Física, FCEyN UBA, Ciudad Universitaria, 1428 Buenos Aires, Argentina
- Max Planck Institute for Molecular Physiology, Department of Systemic Cell Biology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
| | - Frank Jülicher
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany
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47
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Photoperiod-Induced Neuroplasticity in the Circadian System. Neural Plast 2018; 2018:5147585. [PMID: 29681926 PMCID: PMC5851158 DOI: 10.1155/2018/5147585] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/11/2018] [Indexed: 01/01/2023] Open
Abstract
Seasonal changes in light exposure have profound effects on behavioral and physiological functions in many species, including effects on mood and cognitive function in humans. The mammalian brain's master circadian clock, the suprachiasmatic nucleus (SCN), transmits information about external light conditions to other brain regions, including some implicated in mood and cognition. Although the detailed mechanisms are not yet known, the SCN undergoes highly plastic changes at the cellular and network levels under different light conditions. We therefore propose that the SCN may be an essential mediator of the effects of seasonal changes of day length on mental health. In this review, we explore various forms of neuroplasticity that occur in the SCN and other brain regions to facilitate seasonal adaptation, particularly altered phase distribution of cellular circadian oscillators in the SCN and changes in hypothalamic neurotransmitter expression.
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48
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Mendoza-Viveros L, Obrietan K, Cheng HYM. Commentary: miR-132/212 Modulates Seasonal Adaptation and Dendritic Morphology of the Central Circadian Clock. JOURNAL OF NEUROLOGY & NEUROMEDICINE 2018; 3:21-25. [PMID: 29682634 PMCID: PMC5906796 DOI: 10.29245/2572.942x/2017/1.1169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Daily rhythms in behavior and physiology are coordinated by an endogenous clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. This central pacemaker also relays day length information to allow for seasonal adaptation, a process for which melatonin signaling is essential. How the SCN encodes day length is not fully understood. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression by directing target mRNAs for degradation or translational repression. The miR-132/212 cluster plays a key role in facilitating neuronal plasticity, and miR-132 has been shown previously to modulate resetting of the central clock. A recent study from our group showed that miR-132/212 in mice is required for optimal adaptation to seasons and non-24-hour light/dark cycles through regulation of its target gene, methyl CpG-binding protein (MeCP2), in the SCN and dendritic spine density of SCN neurons. Furthermore, in the seasonal rodent Mesocricetus auratus (Syrian hamster), adaptation to short photoperiods is accompanied by structural plasticity in the SCN independently of melatonin signaling, thus further supporting a key role for SCN structural and, in turn, functional plasticity in the coding of day length. In this commentary, we discuss our recent findings in context of what is known about day length encoding by the SCN, and propose future directions.
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Affiliation(s)
- Lucia Mendoza-Viveros
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G3, Canada
| | - Karl Obrietan
- Department of Neuroscience, Ohio State University, Columbus, OH, 43210, USA
| | - Hai-Ying M. Cheng
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G3, Canada
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49
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Abstract
Modern imaging techniques allow the monitoring of circadian rhythms of single cells. Coupling between these single cellular circadian oscillators can generate coherent periodic signals on the tissue level that subsequently orchestrate physiological outputs. The strength of coupling in such systems of oscillators is often unclear. In particular, effects on coupling strength by varying cell densities, by knockouts, and by inhibitor applications are debated. In this study, we suggest to quantify the relative coupling strength via analyzing period, phase, and amplitude distributions in ensembles of individual circadian oscillators. Simulations of different oscillator networks show that period and phase distributions become narrower with increasing coupling strength. Moreover, amplitudes can increase due to resonance effects. Variances of periods and phases decay monotonically with coupling strength, and can serve therefore as measures of relative coupling strength. Our theoretical predictions are confirmed by studying recently published experimental data from PERIOD2 expression in slices of the suprachiasmatic nucleus during and after the application of tetrodotoxin (TTX). On analyzing the corresponding period, phase, and amplitude distributions, we can show that treatment with TTX can be associated with a reduced coupling strength in the system of coupled oscillators. Analysis of an oscillator network derived directly from the data confirms our conclusions. We suggest that our approach is also applicable to quantify coupling in fibroblast cultures and hepatocyte networks, and for social synchronization of circadian rhythmicity in rodents, flies, and bees.
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Affiliation(s)
- Christoph Schmal
- Institute for Theoretical Biology, Charité-Universitätsmedizin, Berlin, Germany
| | - Erik D Herzog
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Hanspeter Herzel
- Institute for Theoretical Biology, Humboldt Universität zu Berlin, Berlin, Germany
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50
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Stevenson TJ. Epigenetic Regulation of Biological Rhythms: An Evolutionary Ancient Molecular Timer. Trends Genet 2017; 34:90-100. [PMID: 29221677 DOI: 10.1016/j.tig.2017.11.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 11/09/2017] [Accepted: 11/15/2017] [Indexed: 01/12/2023]
Abstract
Biological rhythms are pervasive in nature, yet our understanding of the molecular mechanisms that govern timing is far from complete. The rapidly emerging research focus on epigenetic plasticity has revealed a system that is highly dynamic and reversible. In this Opinion, I propose an epigenetic clock model that outlines how molecular modifications, such as DNA methylation, are integral components for timing endogenous biological rhythms. The hypothesis proposed is that an epigenetic clock serves to maintain the period of molecular rhythms via control over the phase of gene transcription and this timing mechanism resides in all cells, from unicellular to complex organisms. The model also provides a novel framework for the timing of epigenetic modifications during the lifespan and transgenerational inheritance of an organism.
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Affiliation(s)
- Tyler J Stevenson
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK.
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