1
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Curtis L, Piggins HD. Diverse genetic alteration dysregulates neuropeptide and intracellular signalling in the suprachiasmatic nuclei. Eur J Neurosci 2024; 60:3921-3945. [PMID: 38924215 DOI: 10.1111/ejn.16443] [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: 12/06/2023] [Revised: 05/12/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024]
Abstract
In mammals, intrinsic 24 h or circadian rhythms are primarily generated by the suprachiasmatic nuclei (SCN). Rhythmic daily changes in the transcriptome and proteome of SCN cells are controlled by interlocking transcription-translation feedback loops (TTFLs) of core clock genes and their proteins. SCN cells function as autonomous circadian oscillators, which synchronize through intercellular neuropeptide signalling. Physiological and behavioural rhythms can be severely disrupted by genetic modification of a diverse range of genes and proteins in the SCN. With the advent of next generation sequencing, there is unprecedented information on the molecular profile of the SCN and how it is affected by genetically targeted alteration. However, whether the expression of some genes is more readily affected by genetic alteration of the SCN is unclear. Here, using publicly available datasets from recent RNA-seq assessments of the SCN from genetically altered and control mice, we evaluated whether there are commonalities in transcriptome dysregulation. This was completed for four different phases across the 24 h cycle and was augmented by Gene Ontology Molecular Function (GO:MF) and promoter analysis. Common differentially expressed genes (DEGs) and/or enriched GO:MF terms included signalling molecules, their receptors, and core clock components. Finally, examination of the JASPAR database indicated that E-box and CRE elements in the promoter regions of several commonly dysregulated genes. From this analysis, we identify differential expression of genes coding for molecules involved in SCN intra- and intercellular signalling as a potential cause of abnormal circadian rhythms.
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Affiliation(s)
- Lucy Curtis
- School of Biological Sciences, University of Bristol, Bristol, UK
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, UK
| | - Hugh D Piggins
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, UK
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2
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Brown MP, Verma S, Palmer I, Guerrero Zuniga A, Mehta A, Rosensweig C, Keles MF, Wu MN. A subclass of evening cells promotes the switch from arousal to sleep at dusk. Curr Biol 2024; 34:2186-2199.e3. [PMID: 38723636 PMCID: PMC11111347 DOI: 10.1016/j.cub.2024.04.039] [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: 08/25/2023] [Revised: 03/20/2024] [Accepted: 04/17/2024] [Indexed: 05/21/2024]
Abstract
Animals exhibit rhythmic patterns of behavior that are shaped by an internal circadian clock and the external environment. Although light intensity varies across the day, there are particularly robust differences at twilight (dawn/dusk). These periods are also associated with major changes in behavioral states, such as the transition from arousal to sleep. However, the neural mechanisms by which time and environmental conditions promote these behavioral transitions are poorly defined. Here, we show that the E1 subclass of Drosophila evening clock neurons promotes the transition from arousal to sleep at dusk. We first demonstrate that the cell-autonomous clocks of E2 neurons primarily drive and adjust the phase of evening anticipation, the canonical behavior associated with "evening" clock neurons. We next show that conditionally silencing E1 neurons causes a significant delay in sleep onset after dusk. However, rather than simply promoting sleep, activating E1 neurons produces time- and light-dependent effects on behavior. Activation of E1 neurons has no effect early in the day but then triggers arousal before dusk and induces sleep after dusk. Strikingly, these activation-induced phenotypes depend on the presence of light during the day. Despite their influence on behavior around dusk, in vivo voltage imaging of E1 neurons reveals that their spiking rate and pattern do not significantly change throughout the day. Moreover, E1-specific clock ablation has no effect on arousal or sleep. Thus, we suggest that, rather than specifying "evening" time, E1 neurons act, in concert with other rhythmic neurons, to promote behavioral transitions at dusk.
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Affiliation(s)
- Matthew P Brown
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Shubha Verma
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Isabelle Palmer
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | | | - Anuradha Mehta
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Clark Rosensweig
- Department of Neurobiology, Northwestern University, Evanston, IL 60201, USA
| | - Mehmet F Keles
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Mark N Wu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA.
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3
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Schlaeger L, Olejniczak I, Lehmann M, Schmidt CX, Astiz M, Oster H, Pilorz V. Estrogen-mediated coupling via gap junctions in the suprachiasmatic nucleus. Eur J Neurosci 2024; 59:1723-1742. [PMID: 38326974 DOI: 10.1111/ejn.16270] [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: 04/04/2023] [Revised: 01/11/2024] [Accepted: 01/22/2024] [Indexed: 02/09/2024]
Abstract
The circadian clock orchestrates many physiological and behavioural rhythms in mammals with 24-h periodicity, through a hierarchical organisation, with the central clock located in the suprachiasmatic nucleus (SCN) in the hypothalamus. The circuits of the SCN generate circadian rhythms with precision, relying on intrinsic coupling mechanisms, for example, neurotransmitters like arginine vasopressin (AVP), vasoactive intestinal peptide (VIP), neuronal gamma-aminobutyric acid (GABA) signalling and astrocytes connected by gap junctions composed of connexins (Cx). In female rodents, the presence of estrogen receptors (ERs) in the dorsal SCN suggests an influence of estrogen (E2) on the circuit timekeeping that could regulate circadian rhythm and coupling. To investigate this, we used SCN explants together with hypothalamic neurons and astrocytes. First, we showed that E2 stabilised the circadian amplitude in the SCN when rAVPs (receptor-associated vasopressin peptides) were inhibited. However, the phase delay induced by VIPAC2 (VIP receptors) inhibition remained unaffected by E2. We then showed that E2 exerted its effects in the SCN via ERβ (estrogen receptor beta), resulting in increased expression of Cx36 and Cx43. Notably, specific inhibition of both connexins resulted in a significant reduction in circadian amplitude within the SCN. Remarkably, E2 restored the period with inhibited Cx36 but not with Cx43 inhibition. This implies that the network between astrocytes and neurons, responsible for coupling in the SCN, can be reinforced through E2. In conclusion, these findings provide new insights into how E2 regulates circadian rhythms ex vivo in an ERβ-dependent manner, underscoring its crucial role in fortifying the SCN's rhythm.
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Affiliation(s)
- Lina Schlaeger
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Iwona Olejniczak
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Marianne Lehmann
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Cosima Xenia Schmidt
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Mariana Astiz
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
- Achucarro Basque Center for Neuroscience, Leioa, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Henrik Oster
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Violetta Pilorz
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
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4
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Mitteldorf J. Biological Clocks: Why We Need Them, Why We Cannot Trust Them, How They Might Be Improved. BIOCHEMISTRY. BIOKHIMIIA 2024; 89:356-366. [PMID: 38622101 DOI: 10.1134/s0006297924020135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 04/17/2024]
Abstract
Late in life, the body is at war with itself. There is a program of self-destruction (phenoptosis) implemented via epigenetic and other changes. I refer to these as type (1) epigenetic changes. But the body retains a deep instinct for survival, and other epigenetic changes unfold in response to a perception of accumulated damage (type (2)). In the past decade, epigenetic clocks have promised to accelerate the search for anti-aging interventions by permitting prompt, reliable, and convenient measurement of their effects on lifespan without having to wait for trial results on mortality and morbidity. However, extant clocks do not distinguish between type (1) and type (2). Reversing type (1) changes extends lifespan, but reversing type (2) shortens lifespan. This is why all extant epigenetic clocks may be misleading. Separation of type (1) and type (2) epigenetic changes will lead to more reliable clock algorithms, but this cannot be done with statistics alone. New experiments are proposed. Epigenetic changes are the means by which the body implements phenoptosis, but they do not embody a clock mechanism, so they cannot be the body's primary timekeeper. The timekeeping mechanism is not yet understood, though there are hints that it may be (partially) located in the hypothalamus. For the future, we expect that the most fundamental measurement of biological age will observe this clock directly, and the most profound anti-aging interventions will manipulate it.
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5
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Brown MP, Verma S, Palmer I, Zuniga AG, Rosensweig C, Keles MF, Wu MN. A subclass of evening cells promotes the switch from arousal to sleep at dusk. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555147. [PMID: 37693540 PMCID: PMC10491161 DOI: 10.1101/2023.08.28.555147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Animals exhibit rhythmic patterns of behavior that are shaped by an internal circadian clock and the external environment. While light intensity varies across the day, there are particularly robust differences at twilight (dawn/dusk). These periods are also associated with major changes in behavioral states, such as the transition from arousal to sleep. However, the neural mechanisms by which time and environmental conditions promote these behavioral transitions are poorly defined. Here, we show that the E1 subclass of Drosophila evening clock neurons promotes the transition from arousal to sleep at dusk. We first demonstrate that the cell-autonomous clocks of E2 neurons alone are required to drive and adjust the phase of evening anticipation, the canonical behavior associated with "evening" clock neurons. We next show that conditionally silencing E1 neurons causes a significant delay in sleep onset after dusk. However, rather than simply promoting sleep, activating E1 neurons produces time- and light- dependent effects on behavior. Activation of E1 neurons has no effect early in the day, but then triggers arousal before dusk and induces sleep after dusk. Strikingly, these phenotypes critically depend on the presence of light during the day. Despite their influence on behavior around dusk, in vivo voltage imaging of E1 neurons reveals that their spiking rate does not vary between dawn and dusk. Moreover, E1-specific clock ablation has no effect on arousal or sleep. Thus, we suggest that, rather than specifying "evening" time, E1 neurons act, in concert with other rhythmic neurons, to promote behavioral transitions at dusk.
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Affiliation(s)
- Matthew P. Brown
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - Shubha Verma
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - Isabelle Palmer
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | | | - Clark Rosensweig
- Department of Neurobiology, Northwestern University, Evanston, IL 60201, U.S.A
| | - Mehmet F. Keles
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - Mark N. Wu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, U.S.A
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
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6
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Duhart JM, Inami S, Koh K. Many faces of sleep regulation: beyond the time of day and prior wake time. FEBS J 2023; 290:931-950. [PMID: 34908236 PMCID: PMC9198110 DOI: 10.1111/febs.16320] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/07/2021] [Accepted: 12/14/2021] [Indexed: 12/19/2022]
Abstract
The two-process model of sleep regulation posits two main processes regulating sleep: the circadian process controlled by the circadian clock and the homeostatic process that depends on the history of sleep and wakefulness. The model has provided a dominant conceptual framework for sleep research since its publication ~ 40 years ago. The time of day and prior wake time are the primary factors affecting the circadian and homeostatic processes, respectively. However, it is critical to consider other factors influencing sleep. Since sleep is incompatible with other behaviors, it is affected by the need for essential behaviors such as eating, foraging, mating, caring for offspring, and avoiding predators. Sleep is also affected by sensory inputs, sickness, increased need for memory consolidation after learning, and other factors. Here, we review multiple factors influencing sleep and discuss recent insights into the mechanisms balancing competing needs.
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Affiliation(s)
- José Manuel Duhart
- Department of Neuroscience, Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia PA
- These authors contributed equally
- Present address: Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Sho Inami
- Department of Neuroscience, Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia PA
- These authors contributed equally
| | - Kyunghee Koh
- Department of Neuroscience, Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia PA
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7
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Kord-Varkaneh H, Salehi-Sahlabadi A, Tinsley GM, Santos HO, Hekmatdoost A. Effects of time-restricted feeding (16/8) combined with a low-sugar diet on the management of non-alcoholic fatty liver disease: A randomized controlled trial. Nutrition 2023; 105:111847. [PMID: 36257081 DOI: 10.1016/j.nut.2022.111847] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/23/2022] [Accepted: 09/05/2022] [Indexed: 10/14/2022]
Abstract
OBJECTIVES Emerging studies have employed time-restricted feeding (TRF) and a low-sugar diet alone in the management of non-alcoholic fatty liver disease (NAFLD), but their combination has not been tested. The aim of this study was to investigate the effects of TRF combined with a low-sugar diet on NAFLD parameters, cardiometabolic and inflammatory biomarkers, and body composition in patients with NAFLD. METHODS A 12-wk randomized controlled trial was performed to compare the effects of TRF (16 h fasting/8 h feeding daily [16/8]) plus a low-sugar diet versus a control diet based on traditional meal distribution in patients with NAFLD. Changes in body composition, anthropometric indices, and liver and cardiometabolic markers were investigated. RESULTS TRF 16/8 with a low-sugar diet reduced body fat (26.7 ± 5.4 to 24.2 ± 4.9 kg), body weight (83.8 ± 12.7 to 80.5 ± 12.1 kg), waist circumference (104.59 ± 10.47 to 101.91 ± 7.42 cm), and body mass index (29.1 ± 2.6 to 28 ± 2.7 kg/m2), as well as circulating levels of fasting blood glucose and liver (alanine aminotransferase, 34 ± 13.9 to 21.2 ± 5.4 U/L; aspartate aminotransferase, 26.3 ± 6.2 to 20.50 ± 4 U/L; γ-glutamyl transpeptidase, 33 ± 15 to 23.2 ± 11.1 U/L; fibrosis score, 6.3 ± 1 to 5.2 ± 1.2 kPa; and controlled attenuation parameter, 322.9 ± 34.9 to 270.9 ± 36.2 dB/m), lipids (triacylglycerols, 201.5 ± 35.3 to 133.3 ± 48.7 mg/dL; total cholesterol, 190 ± 36.6 to 157.8 ± 33.6 mg/dL; and low-density lipoprotein cholesterol, 104.6 ± 27.3 to 84 ± 26.3 mg/dL), and inflammatory markers (high-sensitivity C-reactive protein, 3.1 ± 1.1 to 2 ± 0.9 mg/L; and cytokeratin-18, 1.35 ± 0.03 to 1.16 ± 0.03 ng/mL). These results were statistically significant (P < 0.05) compared with the control group. CONCLUSIONS TRF plus a low-sugar diet can reduce adiposity and improve liver, lipid, and inflammatory markers in patients with NAFLD.
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Affiliation(s)
- Hamed Kord-Varkaneh
- Department of Clinical Nutrition and Dietetics, Faculty of Nutrition and Food Technology, Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ammar Salehi-Sahlabadi
- Department of Clinical Nutrition and Dietetics, Faculty of Nutrition and Food Technology, Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Grant M Tinsley
- Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, Texas, USA
| | - Heitor O Santos
- School of Medicine, Federal University of Uberlandia (UFU), Uberlandia, Minas Gerais, Brazil
| | - Azita Hekmatdoost
- Department of Clinical Nutrition and Dietetics, Faculty of Nutrition and Food Technology, Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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8
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Klerman EB, Brager A, Carskadon MA, Depner CM, Foster R, Goel N, Harrington M, Holloway PM, Knauert MP, LeBourgeois MK, Lipton J, Merrow M, Montagnese S, Ning M, Ray D, Scheer FAJL, Shea SA, Skene DJ, Spies C, Staels B, St‐Onge M, Tiedt S, Zee PC, Burgess HJ. Keeping an eye on circadian time in clinical research and medicine. Clin Transl Med 2022; 12:e1131. [PMID: 36567263 PMCID: PMC9790849 DOI: 10.1002/ctm2.1131] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Daily rhythms are observed in humans and almost all other organisms. Most of these observed rhythms reflect both underlying endogenous circadian rhythms and evoked responses from behaviours such as sleep/wake, eating/fasting, rest/activity, posture changes and exercise. For many research and clinical purposes, it is important to understand the contribution of the endogenous circadian component to these observed rhythms. CONTENT The goal of this manuscript is to provide guidance on best practices in measuring metrics of endogenous circadian rhythms in humans and promote the inclusion of circadian rhythms assessments in studies of health and disease. Circadian rhythms affect all aspects of physiology. By specifying minimal experimental conditions for studies, we aim to improve the quality, reliability and interpretability of research into circadian and daily (i.e., time-of-day) rhythms and facilitate the interpretation of clinical and translational findings within the context of human circadian rhythms. We describe protocols, variables and analyses commonly used for studying human daily rhythms, including how to assess the relative contributions of the endogenous circadian system and other daily patterns in behaviours or the environment. We conclude with recommendations for protocols, variables, analyses, definitions and examples of circadian terminology. CONCLUSION Although circadian rhythms and daily effects on health outcomes can be challenging to distinguish in practice, this distinction may be important in many clinical settings. Identifying and targeting the appropriate underlying (patho)physiology is a medical goal. This review provides methods for identifying circadian effects to aid in the interpretation of published work and the inclusion of circadian factors in clinical research and practice.
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Affiliation(s)
- Elizabeth B. Klerman
- Department of NeurologyMassachusetts General Hospital, Brigham and Women's HospitalBostonMassachusettsUSA
- Division of Sleep MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Allison Brager
- PlansAnalysis, and FuturesJohn F. Kennedy Special Warfare Center and SchoolFort BraggNorth CarolinaUSA
| | - Mary A. Carskadon
- Alpert Medical School of Brown UniversityDepartment of Psychiatry and Human BehaviorEP Bradley HospitalChronobiology and Sleep ResearchProvidenceRhode IslandUSA
| | | | - Russell Foster
- Sir Jules Thorn Sleep and Circadian Neuroscience InstituteNuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
| | - Namni Goel
- Biological Rhythms Research LaboratoryDepartment of Psychiatry and Behavioral SciencesRush University Medical CenterChicagoIllinoisUSA
| | - Mary Harrington
- Neuroscience ProgramSmith CollegeNorthamptonMassachusettsUSA
| | | | - Melissa P. Knauert
- Section of PulmonaryCritical Care, and Sleep MedicineDepartment of Internal MedicineYale School of MedicineNew HavenConnecticutUSA
| | - Monique K. LeBourgeois
- Sleep and Development LaboratoryDepartment of Integrative PhysiologyUniversity of Colorado BoulderBoulderColoradoUSA
| | - Jonathan Lipton
- Boston Children's Hospital and Kirby Neurobiology CenterBostonMassachusettsUSA
| | - Martha Merrow
- Institute of Medical PsychologyFaculty of MedicineLMUMunichGermany
| | - Sara Montagnese
- Department of MedicineUniversity of PadovaPadovaItaly
- ChronobiologyFaculty of Health and Medical SciencesUniversity of SurreyGuildfordUK
| | - Mingming Ning
- Clinical Proteomics Research Center and Cardio‐Neurology DivisionMassachusetts General HospitalHarvard Medical SchoolBostonMassachusettsUSA
| | - David Ray
- NIHR Oxford Biomedical Research CentreJohn Radcliffe HospitalOxfordUK
- Oxford Centre for DiabetesEndocrinology and MetabolismUniversity of OxfordOxfordUK
| | - Frank A. J. L. Scheer
- Division of Sleep MedicineHarvard Medical SchoolBostonMassachusettsUSA
- Medical Chronobiology ProgramDivision of Sleep and Circadian DisordersDepartments of Medicine and NeurologyBrigham and Women's HospitalBostonMassachusettsUSA
| | - Steven A. Shea
- Oregon Institute of Occupational Health SciencesOregon Health and Science UniversityPortlandOregonUSA
| | - Debra J. Skene
- ChronobiologyFaculty of Health and Medical SciencesUniversity of SurreyGuildfordUK
| | - Claudia Spies
- Department of Anesthesiology and Intensive Care MedicineCharité – Universitaetsmedizin BerlinBerlinGermany
| | - Bart Staels
- UnivLilleInsermCHU LilleInstitut Pasteur de LilleU1011‐EGIDLilleFrance
| | - Marie‐Pierre St‐Onge
- Division of General Medicine and Center of Excellence for Sleep and Circadian ResearchDepartment of MedicineColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Steffen Tiedt
- Institute for Stroke and Dementia ResearchUniversity HospitalLMUMunichGermany
| | - Phyllis C. Zee
- Center for Circadian and Sleep MedicineDivision of Sleep MedicineNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
| | - Helen J. Burgess
- Sleep and Circadian Research LaboratoryDepartment of PsychiatryUniversity of MichiganAnn ArborMichiganUSA
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9
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Moeller JS, Bever SR, Finn SL, Phumsatitpong C, Browne MF, Kriegsfeld LJ. Circadian Regulation of Hormonal Timing and the Pathophysiology of Circadian Dysregulation. Compr Physiol 2022; 12:4185-4214. [PMID: 36073751 DOI: 10.1002/cphy.c220018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Circadian rhythms are endogenously generated, daily patterns of behavior and physiology that are essential for optimal health and disease prevention. Disruptions to circadian timing are associated with a host of maladies, including metabolic disease and obesity, diabetes, heart disease, cancer, and mental health disturbances. The circadian timing system is hierarchically organized, with a master circadian clock located in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus and subordinate clocks throughout the CNS and periphery. The SCN receives light information via a direct retinal pathway, synchronizing the master clock to environmental time. At the cellular level, circadian rhythms are ubiquitous, with rhythms generated by interlocking, autoregulatory transcription-translation feedback loops. At the level of the SCN, tight cellular coupling maintains rhythms even in the absence of environmental input. The SCN, in turn, communicates timing information via the autonomic nervous system and hormonal signaling. This signaling couples individual cellular oscillators at the tissue level in extra-SCN brain loci and the periphery and synchronizes subordinate clocks to external time. In the modern world, circadian disruption is widespread due to limited exposure to sunlight during the day, exposure to artificial light at night, and widespread use of light-emitting electronic devices, likely contributing to an increase in the prevalence, and the progression, of a host of disease states. The present overview focuses on the circadian control of endocrine secretions, the significance of rhythms within key endocrine axes for typical, homeostatic functioning, and implications for health and disease when dysregulated. © 2022 American Physiological Society. Compr Physiol 12: 1-30, 2022.
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Affiliation(s)
- Jacob S Moeller
- Graduate Group in Endocrinology, University of California, Berkeley, California, USA
| | - Savannah R Bever
- Department of Psychology, University of California, Berkeley, California, USA
| | - Samantha L Finn
- Department of Psychology, University of California, Berkeley, California, USA
| | | | - Madison F Browne
- Department of Psychology, University of California, Berkeley, California, USA
| | - Lance J Kriegsfeld
- Graduate Group in Endocrinology, University of California, Berkeley, California, USA.,Department of Psychology, University of California, Berkeley, California, USA.,Department of Integrative Biology, University of California, Berkeley, California, USA.,The Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
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10
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Rohr KE, Inda T, Evans JA. Vasopressin Resets the Central Circadian Clock in a Manner Influenced by Sex and Vasoactive Intestinal Polypeptide Signaling. Neuroendocrinology 2022; 112:904-916. [PMID: 34856551 PMCID: PMC9160207 DOI: 10.1159/000521286] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 12/01/2021] [Indexed: 01/03/2023]
Abstract
BACKGROUND/AIMS Circadian rhythms in behavior and physiology are programmed by the suprachiasmatic nucleus (SCN) of the hypothalamus. A subset of SCN neurons produce the neuropeptide arginine vasopressin (AVP), but it remains unclear whether AVP signaling influences the SCN clock directly. METHODS Here, we test that AVP signaling acting through V1A and V1B receptors influences molecular rhythms in SCN neurons. V1 receptor agonists were applied ex vivo to PERIOD2::LUCIFERASE SCN slices, allowing for real-time monitoring of changes in molecular clock function. RESULTS V1A/B agonists reset the phase of the SCN molecular clock in a time-dependent manner, with larger magnitude responses by the female SCN. Further, we found evidence that both Gαq and Gαs signaling pathways interact with V1A/B-induced SCN resetting, and that this response requires vasoactive intestinal polypeptide (VIP) signaling. CONCLUSIONS Collectively, this work indicates that AVP signaling resets SCN molecular rhythms in conjunction with VIP signaling and in a manner influenced by sex. This highlights the utility of studying clock function in both sexes and suggests that signal integration in central clock circuits regulates emergent properties important for the control of daily rhythms in behavior and physiology.
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Affiliation(s)
| | | | - Jennifer A. Evans
- Corresponding author: 560 N 16 St, Schroeder Complex, Room 446, Milwaukee, WI 53233, Phone: 414 288-5732, Fax: 414-288-6564,
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11
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Caliandro R, Streng AA, van Kerkhof LWM, van der Horst GTJ, Chaves I. Social Jetlag and Related Risks for Human Health: A Timely Review. Nutrients 2021; 13:nu13124543. [PMID: 34960096 PMCID: PMC8707256 DOI: 10.3390/nu13124543] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/11/2021] [Accepted: 12/15/2021] [Indexed: 11/16/2022] Open
Abstract
The term social jetlag is used to describe the discrepancy between biological time, determined by our internal body clock, and social times, mainly dictated by social obligations such as school or work. In industrialized countries, two-thirds of the studying/working population experiences social jetlag, often for several years. Described for the first time in 2006, a considerable effort has been put into understanding the effects of social jetlag on human physiopathology, yet our understanding of this phenomenon is still very limited. Due to its high prevalence, social jetlag is becoming a primary concern for public health. This review summarizes current knowledge regarding social jetlag, social jetlag associated behavior (e.g., unhealthy eating patterns) and related risks for human health.
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Affiliation(s)
- Rocco Caliandro
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Centre Rotterdam, 3015 GD Rotterdam, The Netherlands; (R.C.); (A.A.S.); (G.T.J.v.d.H.)
| | - Astrid A. Streng
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Centre Rotterdam, 3015 GD Rotterdam, The Netherlands; (R.C.); (A.A.S.); (G.T.J.v.d.H.)
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), 3721 MA Bilthoven, The Netherlands;
| | - Linda W. M. van Kerkhof
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), 3721 MA Bilthoven, The Netherlands;
| | - Gijsbertus T. J. van der Horst
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Centre Rotterdam, 3015 GD Rotterdam, The Netherlands; (R.C.); (A.A.S.); (G.T.J.v.d.H.)
| | - Inês Chaves
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Centre Rotterdam, 3015 GD Rotterdam, The Netherlands; (R.C.); (A.A.S.); (G.T.J.v.d.H.)
- Correspondence: ; Tel.: +31-10-704-3456; Fax: +31-10-704-4743
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12
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Gu C, Li J, Zhou J, Yang H, Rohling J. Network Structure of the Master Clock Is Important for Its Primary Function. Front Physiol 2021; 12:678391. [PMID: 34483953 PMCID: PMC8415478 DOI: 10.3389/fphys.2021.678391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/22/2021] [Indexed: 11/13/2022] Open
Abstract
A master clock located in the suprachiasmatic nucleus (SCN) regulates the circadian rhythm of physiological and behavioral activities in mammals. The SCN has two main functions in the regulation: an endogenous clock produces the endogenous rhythmic signal in body rhythms, and a calibrator synchronizes the body rhythms to the external light-dark cycle. These two functions have been determined to depend on either the dynamic behaviors of individual neurons or the whole SCN neuronal network. In this review, we first introduce possible network structures for the SCN, as revealed by time series analysis from real experimental data. It was found that the SCN network is heterogeneous and sparse, that is, the average shortest path length is very short, some nodes are hubs with large node degrees but most nodes have small node degrees, and the average node degree of the network is small. Secondly, the effects of the SCN network structure on the SCN function are reviewed based on mathematical models of the SCN network. It was found that robust rhythms with large amplitudes, a high synchronization between SCN neurons and a large entrainment ability exists mainly in small-world and scale-free type networks, but not other types. We conclude that the SCN most probably is an efficient small-world type or scale-free type network, which drives SCN function.
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Affiliation(s)
- Changgui Gu
- Business School, University of Shanghai for Science and Technology, Shanghai, China
| | - Jiahui Li
- Business School, University of Shanghai for Science and Technology, Shanghai, China
| | - Jian Zhou
- Business School, University of Shanghai for Science and Technology, Shanghai, China
| | - Huijie Yang
- Business School, University of Shanghai for Science and Technology, Shanghai, China
| | - Jos Rohling
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
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13
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Sueviriyapan N, Granados-Fuentes D, Simon T, Herzog ED, Henson MA. Modelling the functional roles of synaptic and extra-synaptic γ-aminobutyric acid receptor dynamics in circadian timekeeping. J R Soc Interface 2021; 18:20210454. [PMID: 34520693 PMCID: PMC8440032 DOI: 10.1098/rsif.2021.0454] [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: 06/01/2021] [Accepted: 08/23/2021] [Indexed: 11/12/2022] Open
Abstract
In the suprachiasmatic nucleus (SCN), γ-aminobutyric acid (GABA) is a primary neurotransmitter. GABA can signal through two types of GABAA receptor subunits, often referred to as synaptic GABAA (gamma subunit) and extra-synaptic GABAA (delta subunit). To test the functional roles of these distinct GABAA in regulating circadian rhythms, we developed a multicellular SCN model where we could separately compare the effects of manipulating GABA neurotransmitter or receptor dynamics. Our model predicted that blocking GABA signalling modestly increased synchrony among circadian cells, consistent with published SCN pharmacology. Conversely, the model predicted that lowering GABAA receptor density reduced firing rate, circadian cell fraction, amplitude and synchrony among individual neurons. When we tested these predictions, we found that the knockdown of delta GABAA reduced the amplitude and synchrony of clock gene expression among cells in SCN explants. The model further predicted that increasing gamma GABAA densities could enhance synchrony, as opposed to increasing delta GABAA densities. Overall, our model reveals how blocking GABAA receptors can modestly increase synchrony, while increasing the relative density of gamma over delta subunits can dramatically increase synchrony. We hypothesize that increased gamma GABAA density in the winter could underlie the tighter phase relationships among SCN cells.
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Affiliation(s)
- Natthapong Sueviriyapan
- Department of Chemical Engineering and the Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, USA
| | | | - Tatiana Simon
- Department of Biology, Washington University in St Louis, Saint Louis, MO, USA
| | - Erik D. Herzog
- Department of Biology, Washington University in St Louis, Saint Louis, MO, USA
| | - Michael A. Henson
- Department of Chemical Engineering and the Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, USA
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14
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Baluška F, Reber AS. CBC-Clock Theory of Life - Integration of cellular circadian clocks and cellular sentience is essential for cognitive basis of life. Bioessays 2021; 43:e2100121. [PMID: 34382225 DOI: 10.1002/bies.202100121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/16/2021] [Accepted: 07/19/2021] [Indexed: 12/20/2022]
Abstract
Cellular circadian clocks represent ancient anticipatory systems which co-evolved with the first cells to safeguard their survival. Cyanobacteria represent one of the most ancient cells, having essentially invented photosynthesis together with redox-based cellular circadian clocks some 2.7 billion years ago. Bioelectricity phenomena, based on redox homeostasis associated electron transfers in membranes and within protein complexes inserted in excitable membranes, play important roles, not only in the cellular circadian clocks and in anesthetics-sensitive cellular sentience (awareness of environment), but also in the coupling of single cells into tissues and organs of unitary multicellular organisms. This integration of cellular circadian clocks with cellular basis of sentience is an essential feature of the cognitive CBC-Clock basis of cellular life.
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Affiliation(s)
- František Baluška
- Institute of Cellular and Molecular Botany, University of Bonn, Bonn, Germany
| | - Arthur S Reber
- Department of Psychology, University of British Columbia, Vancouver, Canada
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15
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Joye DAM, Evans JA. Sex differences in daily timekeeping and circadian clock circuits. Semin Cell Dev Biol 2021; 126:45-55. [PMID: 33994299 DOI: 10.1016/j.semcdb.2021.04.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/24/2021] [Accepted: 04/29/2021] [Indexed: 11/19/2022]
Abstract
The circadian system regulates behavior and physiology in many ways important for health. Circadian rhythms are expressed by nearly every cell in the body, and this large system is coordinated by a central clock in the suprachiasmatic nucleus (SCN). Sex differences in daily rhythms are evident in humans and understanding how circadian function is modulated by biological sex is an important goal. This review highlights work examining effects of sex and gonadal hormones on daily rhythms, with a focus on behavior and SCN circuitry in animal models commonly used in pre-clinical studies. Many questions remain in this area of the field, which would benefit from further work investigating this topic.
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Affiliation(s)
- Deborah A M Joye
- Marquette University, Department of Biomedical Sciences, Milwaukee, WI, USA
| | - Jennifer A Evans
- Marquette University, Department of Biomedical Sciences, Milwaukee, WI, USA.
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16
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Buijink MR, Michel S. A multi-level assessment of the bidirectional relationship between aging and the circadian clock. J Neurochem 2021; 157:73-94. [PMID: 33370457 PMCID: PMC8048448 DOI: 10.1111/jnc.15286] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 12/15/2022]
Abstract
The daily temporal order of physiological processes and behavior contribute to the wellbeing of many organisms including humans. The central circadian clock, which coordinates the timing within our body, is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Like in other parts of the brain, aging impairs the SCN function, which in turn promotes the development and progression of aging-related diseases. We here review the impact of aging on the different levels of the circadian clock machinery-from molecules to organs-with a focus on the role of the SCN. We find that the molecular clock is less effected by aging compared to other cellular components of the clock. Proper rhythmic regulation of intracellular signaling, ion channels and neuronal excitability of SCN neurons are greatly disturbed in aging. This suggests a disconnection between the molecular clock and the electrophysiology of these cells. The neuronal network of the SCN is able to compensate for some of these cellular deficits. However, it still results in a clear reduction in the amplitude of the SCN electrical rhythm, suggesting a weakening of the output timing signal. Consequently, other brain areas and organs not only show aging-related deficits in their own local clocks, but also receive a weaker systemic timing signal. The negative spiral completes with the weakening of positive feedback from the periphery to the SCN. Consequently, chronotherapeutic interventions should aim at strengthening overall synchrony in the circadian system using life-style and/or pharmacological approaches.
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Affiliation(s)
- M. Renate Buijink
- Department of Cellular and Chemical BiologyLaboratory for NeurophysiologyLeiden University Medical CenterLeidenthe Netherlands
| | - Stephan Michel
- Department of Cellular and Chemical BiologyLaboratory for NeurophysiologyLeiden University Medical CenterLeidenthe Netherlands
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17
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Rojas M, Chávez-Castillo M, Pírela D, Ortega Á, Salazar J, Cano C, Chacín M, Riaño M, Batista MJ, Díaz EA, Rojas-Quintero J, Bermúdez V. Chronobiology and Chronotherapy in Depression: Current Knowledge and Chronotherapeutic Promises. CURRENT PSYCHIATRY RESEARCH AND REVIEWS 2021. [DOI: 10.2174/2666082216999201124152432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Depression is a heavily prevalent mental disorder. Symptoms of depression
extend beyond mood, cognition, and behavior to include a spectrum of somatic manifestations in all
organic systems. Changes in sleep and neuroendocrine rhythms are especially prominent, and disruptions
of circadian rhythms have been closely related to the neurobiology of depression. With the
advent of increased research in chronobiology, various pathophysiologic mechanisms have been
proposed, including anomalies of sleep architecture, the effects of clock gene polymorphisms in
monoamine metabolism, and the deleterious impact of social zeitgebers. The identification of these
chronodisruptions has propelled the emergence of several chronotherapeutic strategies, both pharmacological
and non-pharmacological, with varying degrees of clinical evidence.
Methods:
The fundamental objective of this review is to integrate current knowledge about the role
of chronobiology and depression and to summarize the interventions developed to resynchronize
biorhythms both within an individual and with geophysical time.
Results:
We have found that among the non-pharmacological alternatives, triple chronotherapywhich
encompasses bright light therapy, sleep deprivation therapy, and consecutive sleep phase
advance therapy-has garnered the most considerable scientific interest. On the other hand,
agomelatine appears to be the most promising pharmacological option, given its unique melatonergic
pharmacodynamics.
Conclusions:
Research in chronotherapy as a treatment for depression is currently booming. Novel
interventions could play a significant role in adopting new options for the treatment of depression,
with Tripe Cronotherapy standing out as the most promising treatment.
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Affiliation(s)
- Milagros Rojas
- Endocrine and Metabolic Diseases Research Center, School of Medicine, University of Zulia, Maracaibo, Venezuela
| | - Mervin Chávez-Castillo
- Endocrine and Metabolic Diseases Research Center, School of Medicine, University of Zulia, Maracaibo, Venezuela
| | - Daniela Pírela
- Endocrine and Metabolic Diseases Research Center, School of Medicine, University of Zulia, Maracaibo, Venezuela
| | - Ángel Ortega
- Endocrine and Metabolic Diseases Research Center, School of Medicine, University of Zulia, Maracaibo, Venezuela
| | - Juan Salazar
- Endocrine and Metabolic Diseases Research Center, School of Medicine, University of Zulia, Maracaibo, Venezuela
| | - Clímaco Cano
- Endocrine and Metabolic Diseases Research Center, School of Medicine, University of Zulia, Maracaibo, Venezuela
| | - Maricarmen Chacín
- Universidad Simon Bolivar, Facultad de Ciencias de la Salud, Barranquilla, Colombia
| | - Manuel Riaño
- Universidad Simon Bolívar, Facultad de Ciencias Juridicas y Sociales, Cucuta, Colombia
| | - María Judith Batista
- Universidad Simon Bolívar, Facultad de Ciencias Juridicas y Sociales, Cucuta, Colombia
| | - Edgar Alexis Díaz
- Universidad Simon Bolívar, Facultad de Ciencias Juridicas y Sociales, Cucuta, Colombia
| | - Joselyn Rojas-Quintero
- Pulmonary and Critical Care Medicine Department, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, United States
| | - Valmore Bermúdez
- Universidad Simon Bolivar, Facultad de Ciencias de la Salud, Barranquilla, Colombia
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18
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Rohr KE, Telega A, Savaglio A, Evans JA. Vasopressin regulates daily rhythms and circadian clock circuits in a manner influenced by sex. Horm Behav 2021; 127:104888. [PMID: 33202247 PMCID: PMC7855892 DOI: 10.1016/j.yhbeh.2020.104888] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/30/2020] [Accepted: 11/04/2020] [Indexed: 12/17/2022]
Abstract
Arginine vasopressin (AVP) is a neurohormone that alters cellular physiology through both endocrine and synaptic signaling. Circadian rhythms in AVP release and other biological processes are driven by the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. Loss of vasopressin signaling alters circadian behavior, but the basis of these effects remains unclear. Here we investigate the role of AVP signaling in circadian timekeeping by analyzing behavior and SCN function in a novel AVP-deficient mouse model. Consistent with previous work, loss of AVP signaling increases water consumption and accelerates recovery to simulated jetlag. We expand on these results to show that loss of AVP increases period, imprecision and plasticity of behavioral rhythms under constant darkness. Interestingly, the effect of AVP deficiency on circadian period was influenced by sex, with loss of AVP lengthening period in females but not males. Examining SCN function directly with ex vivo bioluminescence imaging of clock protein expression, we demonstrate that loss of AVP signaling modulates the period, precision, and phase relationships of SCN neurons in both sexes. This pattern of results suggests that there are likely sex differences in downstream targets of the SCN. Collectively, this work indicates that AVP signaling modulates circadian circuits in a manner influenced by sex, which provides new insight into sexual dimorphisms in the regulation of daily rhythms.
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Affiliation(s)
- Kayla E Rohr
- Marquette University, Department of Biomedical Sciences, United States of America
| | - Adam Telega
- Marquette University, Department of Biomedical Sciences, United States of America
| | - Alexandra Savaglio
- Marquette University, Department of Biomedical Sciences, United States of America
| | - Jennifer A Evans
- Marquette University, Department of Biomedical Sciences, United States of America.
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19
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Joye DAM, Evans JA. Marking Time: Colorful New Insights into Master Clock Circuits. Neuron 2020; 108:2-5. [PMID: 33058763 DOI: 10.1016/j.neuron.2020.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A neural clock controls what we do each day, and understanding its circuitry is important for health. In this issue of Neuron, Shan et al. visualize molecular rhythms in subtypes of master clock neurons to test principles of cell identity and network wiring.
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Affiliation(s)
- Deborah A M Joye
- Department of Biomedical Sciences, Marquette University, 560 N 16(th) St, Schroeder Complex, Room 446, Milwaukee, WI 53233, USA
| | - Jennifer A Evans
- Department of Biomedical Sciences, Marquette University, 560 N 16(th) St, Schroeder Complex, Room 446, Milwaukee, WI 53233, USA.
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20
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Vasopressin in circadian function of SCN. J Biosci 2020. [DOI: 10.1007/s12038-020-00109-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Sueviriyapan N, Tso CF, Herzog ED, Henson MA. Astrocytic Modulation of Neuronal Activity in the Suprachiasmatic Nucleus: Insights from Mathematical Modeling. J Biol Rhythms 2020; 35:287-301. [PMID: 32285754 PMCID: PMC7401727 DOI: 10.1177/0748730420913672] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The suprachiasmatic nucleus (SCN) of the hypothalamus consists of a highly heterogeneous neuronal population networked together to allow precise and robust circadian timekeeping in mammals. While the critical importance of SCN neurons in regulating circadian rhythms has been extensively studied, the roles of SCN astrocytes in circadian system function are not well understood. Recent experiments have demonstrated that SCN astrocytes are circadian oscillators with the same functional clock genes as SCN neurons. Astrocytes generate rhythmic outputs that are thought to modulate neuronal activity through pre- and postsynaptic interactions. In this study, we developed an in silico multicellular model of the SCN clock to investigate the impact of astrocytes in modulating neuronal activity and affecting key clock properties such as circadian rhythmicity, period, and synchronization. The model predicted that astrocytes could alter the rhythmic activity of neurons via bidirectional interactions at tripartite synapses. Specifically, astrocyte-regulated extracellular glutamate was predicted to increase neuropeptide signaling from neurons. Consistent with experimental results, we found that astrocytes could increase the circadian period and enhance neural synchronization according to their endogenous circadian period. The impact of astrocytic modulation of circadian rhythm amplitude, period, and synchronization was predicted to be strongest when astrocytes had periods between 0 and 2 h longer than neurons. Increasing the number of neurons coupled to the astrocyte also increased its impact on period modulation and synchrony. These computational results suggest that signals that modulate astrocytic rhythms or signaling (e.g., as a function of season, age, or treatment) could cause disruptions in circadian rhythm or serve as putative therapeutic targets.
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Affiliation(s)
- Natthapong Sueviriyapan
- Department of Chemical Engineering and the Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA 01003, USA
| | - Chak Foon Tso
- Department of Biology, Washington University in St. Louis, Saint Louis, MO 63130, USA
- Current Affiliation: Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA
| | - Erik D. Herzog
- Department of Biology, Washington University in St. Louis, Saint Louis, MO 63130, USA
| | - Michael A. Henson
- Department of Chemical Engineering and the Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA 01003, USA
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22
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Joye DAM, Rohr KE, Keller D, Inda T, Telega A, Pancholi H, Carmona-Alcocer V, Evans JA. Reduced VIP Expression Affects Circadian Clock Function in VIP-IRES-CRE Mice (JAX 010908). J Biol Rhythms 2020; 35:340-352. [PMID: 32460660 DOI: 10.1177/0748730420925573] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Circadian rhythms are programmed by the suprachiasmatic nucleus (SCN), which relies on neuropeptide signaling to maintain daily timekeeping. Vasoactive intestinal polypeptide (VIP) is critical for SCN function, but the precise role of VIP neurons in SCN circuits is not fully established. To interrogate their contribution to SCN circuits, VIP neurons can be manipulated specifically using the DNA-editing enzyme Cre recombinase. Although the Cre transgene is assumed to be inert by itself, we find that VIP expression is reduced in both heterozygous and homozygous adult VIP-IRES-Cre mice (JAX 010908). Compared with wild-type mice, homozygous VIP-Cre mice display faster reentrainment and shorter free-running period but do not become arrhythmic in constant darkness. Consistent with this phenotype, homozygous VIP-Cre mice display intact SCN PER2::LUC rhythms, albeit with altered period and network organization. We present evidence that the ability to sustain molecular rhythms in the VIP-Cre SCN is not due to residual VIP signaling; rather, arginine vasopressin signaling helps to sustain SCN function at both intracellular and intercellular levels in this model. This work establishes that the VIP-IRES-Cre transgene interferes with VIP expression but that loss of VIP can be mitigated by other neuropeptide signals to help sustain SCN function. Our findings have implications for studies employing this transgenic model and provide novel insight into neuropeptide signals that sustain daily timekeeping in the master clock.
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Affiliation(s)
- Deborah A M Joye
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin
| | - Kayla E Rohr
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin
| | - Danielle Keller
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin
| | - Thomas Inda
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin
| | - Adam Telega
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin
| | - Harshida Pancholi
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin
| | | | - Jennifer A Evans
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin
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23
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McNeill JK, Walton JC, Ryu V, Albers HE. The Excitatory Effects of GABA within the Suprachiasmatic Nucleus: Regulation of Na-K-2Cl Cotransporters (NKCCs) by Environmental Lighting Conditions. J Biol Rhythms 2020; 35:275-286. [PMID: 32406304 DOI: 10.1177/0748730420924271] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The suprachiasmatic nucleus (SCN) contains a pacemaker that generates circadian rhythms and entrains them with the 24-h light-dark cycle (LD). The SCN is composed of 16,000 to 20,000 heterogeneous neurons in bilaterally paired nuclei. γ-amino butyric acid (GABA) is the primary neurochemical signal within the SCN and plays a key role in regulating circadian function. While GABA is the primary inhibitory neurotransmitter in the brain, there is now evidence that GABA can also exert excitatory effects in the adult brain. Cation chloride cotransporters determine the effects of GABA on chloride equilibrium, thereby determining whether GABA produces hyperpolarizing or depolarizing actions following activation of GABAA receptors. The activity of Na-K-2Cl cotransporter1 (NKCC1), the most prevalent chloride influx cotransporter isoform in the brain, plays a critical role in determining whether GABA has depolarizing effects. In the present study, we tested the hypothesis that NKCC1 protein expression in the SCN is regulated by environmental lighting and displays daily and circadian changes in the intact circadian system of the Syrian hamster. In hamsters housed in constant light (LL), the overall NKCC1 immunoreactivity (NKCC1-ir) in the SCN was significantly greater than in hamsters housed in LD or constant darkness (DD), although NKCC1 protein levels in the SCN were not different between hamsters housed in LD and DD. In hamsters housed in LD cycles, no differences in NKCC1-ir within the SCN were observed over the 24-h cycle. NKCC1 protein in the SCN was found to vary significantly over the circadian cycle in hamsters housed in free-running conditions. Overall, NKCC1 protein was greater in the ventral SCN than in the dorsal SCN, although no significant differences were observed across lighting conditions or time of day in either subregion. These data support the hypothesis that NKCC1 protein expression can be regulated by environmental lighting and circadian mechanisms within the SCN.
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Affiliation(s)
- John K McNeill
- Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, Georgia
| | - James C Walton
- Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, Georgia
| | - Vitaly Ryu
- Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, Georgia
| | - H Elliott Albers
- Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, Georgia
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24
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Paul S, Hanna L, Harding C, Hayter EA, Walmsley L, Bechtold DA, Brown TM. Output from VIP cells of the mammalian central clock regulates daily physiological rhythms. Nat Commun 2020; 11:1453. [PMID: 32193397 PMCID: PMC7081308 DOI: 10.1038/s41467-020-15277-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 02/29/2020] [Indexed: 12/27/2022] Open
Abstract
The suprachiasmatic nucleus (SCN) circadian clock is critical for optimising daily cycles in mammalian physiology and behaviour. The roles of the various SCN cell types in communicating timing information to downstream physiological systems remain incompletely understood, however. In particular, while vasoactive intestinal polypeptide (VIP) signalling is essential for SCN function and whole animal circadian rhythmicity, the specific contributions of VIP cell output to physiological control remains uncertain. Here we reveal a key role for SCN VIP cells in central clock output. Using multielectrode recording and optogenetic manipulations, we show that VIP neurons provide coordinated daily waves of GABAergic input to target cells across the paraventricular hypothalamus and ventral thalamus, supressing their activity during the mid to late day. Using chemogenetic manipulation, we further demonstrate specific roles for this circuitry in the daily control of heart rate and corticosterone secretion, collectively establishing SCN VIP cells as influential regulators of physiological timing. VIP-expressing neurons play a central role in circadian timekeeping within the mammalian central clock. Here the authors use opto- and chemogenetic approaches to show that VIP neuronal activity regulates rhythmic activity in downstream hypothalamic target neurons and their physiological functions.
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Affiliation(s)
- Sarika Paul
- Centre for Biological timing, Faculty of Biology Medicine & Health, University of Manchester, Manchester, UK
| | - Lydia Hanna
- Centre for Biological timing, Faculty of Biology Medicine & Health, University of Manchester, Manchester, UK.,School of Pharmacy, University of Reading, Reading, UK
| | - Court Harding
- Centre for Biological timing, Faculty of Biology Medicine & Health, University of Manchester, Manchester, UK
| | - Edward A Hayter
- Centre for Biological timing, Faculty of Biology Medicine & Health, University of Manchester, Manchester, UK
| | - Lauren Walmsley
- Centre for Biological timing, Faculty of Biology Medicine & Health, University of Manchester, Manchester, UK
| | - David A Bechtold
- Centre for Biological timing, Faculty of Biology Medicine & Health, University of Manchester, Manchester, UK
| | - Timothy M Brown
- Centre for Biological timing, Faculty of Biology Medicine & Health, University of Manchester, Manchester, UK.
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25
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Pilorz V, Astiz M, Heinen KO, Rawashdeh O, Oster H. The Concept of Coupling in the Mammalian Circadian Clock Network. J Mol Biol 2020; 432:3618-3638. [PMID: 31926953 DOI: 10.1016/j.jmb.2019.12.037] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 12/22/2019] [Accepted: 12/23/2019] [Indexed: 12/13/2022]
Abstract
The circadian clock network regulates daily rhythms in mammalian physiology and behavior to optimally adapt the organism to the 24-h day/night cycle. A central pacemaker, the hypothalamic suprachiasmatic nucleus (SCN), coordinates subordinate cellular oscillators in the brain, as well as in peripheral organs to align with each other and external time. Stability and coordination of this vast network of cellular oscillators is achieved through different levels of coupling. Although coupling at the molecular level and across the SCN is well established and believed to define its function as pacemaker structure, the notion of coupling in other tissues and across the whole system is less well understood. In this review, we describe the different levels of coupling in the mammalian circadian clock system - from molecules to the whole organism. We highlight recent advances in gaining knowledge of the complex organization and function of circadian network regulation and its significance for the generation of stable but plastic intrinsic 24-h rhythms.
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Affiliation(s)
- Violetta Pilorz
- University of Lübeck, Institute of Neurobiology, Center of Brain, Behavior and Metabolism, Marie-Curie-Strasse, 23562, Luebeck, Germany
| | - Mariana Astiz
- University of Lübeck, Institute of Neurobiology, Center of Brain, Behavior and Metabolism, Marie-Curie-Strasse, 23562, Luebeck, Germany
| | - Keno Ole Heinen
- University of Lübeck, Institute of Neurobiology, Center of Brain, Behavior and Metabolism, Marie-Curie-Strasse, 23562, Luebeck, Germany
| | - Oliver Rawashdeh
- The University of Queensland, School of Biomedical Sciences, Faculty of Medicine, St Lucia Qld, 4071, Australia
| | - Henrik Oster
- University of Lübeck, Institute of Neurobiology, Center of Brain, Behavior and Metabolism, Marie-Curie-Strasse, 23562, Luebeck, Germany.
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26
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Mindikoglu AL, Abdulsada MM, Jain A, Choi JM, Jalal PK, Devaraj S, Mezzari MP, Petrosino JF, Opekun AR, Jung SY. Intermittent fasting from dawn to sunset for 30 consecutive days is associated with anticancer proteomic signature and upregulates key regulatory proteins of glucose and lipid metabolism, circadian clock, DNA repair, cytoskeleton remodeling, immune system and cognitive function in healthy subjects. J Proteomics 2020; 217:103645. [PMID: 31927066 DOI: 10.1016/j.jprot.2020.103645] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 12/13/2019] [Accepted: 01/08/2020] [Indexed: 02/06/2023]
Abstract
Murine studies showed that disruption of circadian clock rhythmicity could lead to cancer and metabolic syndrome. Time-restricted feeding can reset the disrupted clock rhythm, protect against cancer and metabolic syndrome. Based on these observations, we hypothesized that intermittent fasting for several consecutive days without calorie restriction in humans would induce an anticarcinogenic proteome and the key regulatory proteins of glucose and lipid metabolism. Fourteen healthy subjects fasted from dawn to sunset for over 14 h daily. Fasting duration was 30 consecutive days. Serum samples were collected before 30-day intermittent fasting, at the end of 4th week during 30-day intermittent fasting, and one week after 30-day intermittent fasting. An untargeted serum proteomic profiling was performed using ultra high-performance liquid chromatography/tandem mass spectrometry. Our results showed that 30-day intermittent fasting was associated with an anticancer serum proteomic signature, upregulated key regulatory proteins of glucose and lipid metabolism, circadian clock, DNA repair, cytoskeleton remodeling, immune system, and cognitive function, and resulted in a serum proteome protective against cancer, metabolic syndrome, inflammation, Alzheimer's disease, and several neuropsychiatric disorders. These findings suggest that fasting from dawn to sunset for 30 consecutive days can be preventive and adjunct therapy in cancer, metabolic syndrome, and several cognitive and neuropsychiatric diseases. SIGNIFICANCE: Our study has important clinical implications. Our results showed that intermittent fasting from dawn to sunset for over 14 h daily for 30 consecutive days was associated with an anticancer serum proteomic signature and upregulated key regulatory proteins of glucose and lipid metabolism, insulin signaling, circadian clock, DNA repair, cytoskeleton remodeling, immune system, and cognitive function, and resulted in a serum proteome protective against cancer, obesity, diabetes, metabolic syndrome, inflammation, Alzheimer's disease, and several neuropsychiatric disorders. Importantly, these findings occurred in the absence of any calorie restriction and significant weight loss. These findings suggest that intermittent fasting from dawn to sunset can be a preventive and adjunct therapy in cancer, metabolic syndrome and Alzheimer's disease and several neuropsychiatric diseases.
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Affiliation(s)
- Ayse L Mindikoglu
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, United States of America; Michael E. DeBakey Department of Surgery, Division of Abdominal Transplantation, Baylor College of Medicine, Houston, TX, United States of America.
| | - Mustafa M Abdulsada
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, United States of America
| | - Antrix Jain
- Advanced Technology Core, Mass Spectrometry Proteomics Core, Baylor College of Medicine, Houston, TX, United States of America
| | - Jong Min Choi
- Advanced Technology Core, Mass Spectrometry Proteomics Core, Baylor College of Medicine, Houston, TX, United States of America
| | - Prasun K Jalal
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, United States of America; Michael E. DeBakey Department of Surgery, Division of Abdominal Transplantation, Baylor College of Medicine, Houston, TX, United States of America
| | - Sridevi Devaraj
- Clinical Chemistry and Point of Care Technology, Texas Children's Hospital and Health Centers, Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, United States of America
| | - Melissa P Mezzari
- The Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX, United States of America
| | - Joseph F Petrosino
- The Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX, United States of America
| | - Antone R Opekun
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, United States of America; Department of Pediatrics, Division of Gastroenterology, Nutrition and Hepatology, Baylor College of Medicine, Houston, TX, United States of America
| | - Sung Yun Jung
- Advanced Technology Core, Mass Spectrometry Proteomics Core, Baylor College of Medicine, Houston, TX, United States of America; Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX, United States of America
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27
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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: 30] [Impact Index Per Article: 6.0] [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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28
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Schlichting M, Díaz MM, Xin J, Rosbash M. Neuron-specific knockouts indicate the importance of network communication to Drosophila rhythmicity. eLife 2019; 8:e48301. [PMID: 31613223 PMCID: PMC6794074 DOI: 10.7554/elife.48301] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 09/24/2019] [Indexed: 12/16/2022] Open
Abstract
Animal circadian rhythms persist in constant darkness and are driven by intracellular transcription-translation feedback loops. Although these cellular oscillators communicate, isolated mammalian cellular clocks continue to tick away in darkness without intercellular communication. To investigate these issues in Drosophila, we assayed behavior as well as molecular rhythms within individual brain clock neurons while blocking communication within the ca. 150 neuron clock network. We also generated CRISPR-mediated neuron-specific circadian clock knockouts. The results point to two key clock neuron groups: loss of the clock within both regions but neither one alone has a strong behavioral phenotype in darkness; communication between these regions also contributes to circadian period determination. Under these dark conditions, the clock within one region persists without network communication. The clock within the famous PDF-expressing s-LNv neurons however was strongly dependent on network communication, likely because clock gene expression within these vulnerable sLNvs depends on neuronal firing or light.
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Affiliation(s)
- Matthias Schlichting
- Department of BiologyHoward Hughes Medical Institute, Brandeis UniversityWalthamUnited States
| | - Madelen M Díaz
- Department of BiologyHoward Hughes Medical Institute, Brandeis UniversityWalthamUnited States
| | - Jason Xin
- Department of BiologyHoward Hughes Medical Institute, Brandeis UniversityWalthamUnited States
| | - Michael Rosbash
- Department of BiologyHoward Hughes Medical Institute, Brandeis UniversityWalthamUnited States
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29
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Abstract
Numerous physiological functions exhibit substantial circadian oscillations. In the kidneys, renal plasma flow, the glomerular filtration rate and tubular reabsorption and/or secretion processes have been shown to peak during the active phase and decline during the inactive phase. These functional rhythms are driven, at least in part, by a self-sustaining cellular mechanism termed the circadian clock. The circadian clock controls different cellular functions, including transcription, translation and protein post-translational modifications (such as phosphorylation, acetylation and ubiquitylation) and degradation. Disruption of the circadian clock in animal models results in the loss of blood pressure control and substantial changes in the circadian pattern of water and electrolyte excretion in the urine. Kidney-specific suppression of the circadian clock in animals implicates both the intrinsic renal and the extrarenal circadian clocks in these pathologies. Alterations in the circadian rhythm of renal functions are associated with the development of hypertension, chronic kidney disease, renal fibrosis and kidney stones. Furthermore, renal circadian clocks might interfere with the pharmacokinetics and/or pharmacodynamics of various drugs and are therefore an important consideration in the treatment of some renal diseases or disorders.
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Affiliation(s)
- Dmitri Firsov
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.
| | - Olivier Bonny
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland. .,Service of Nephrology, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland.
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30
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Hannibal J, Norn THB, Georg B, Fahrenkrug J. Spatiotemporal expression pattern of PERIOD 1 and PERIOD 2 in the mouse SCN is dependent on VIP receptor 2 signaling. Eur J Neurosci 2019; 50:3115-3132. [PMID: 31211910 DOI: 10.1111/ejn.14482] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 04/29/2019] [Accepted: 05/21/2019] [Indexed: 11/29/2022]
Abstract
Neurons of the hypothalamic suprachiasmatic nucleus (SCN) express clock genes, which regulate their own transcription and generate daily output signals driving circadian rhythmic behavior and physiology. The neuropeptide VIP and its specific receptor, the VPAC2 receptor, are important for synchronization of clock neurons. In the present study, we characterized PER1 and PER2 expressing neurons in wild-type and VPAC2-deficient mice. We found evidence for distinct spatiotemporal circadian oscillation in the expression of the PER genes in two separate clusters of SCN neurons. In wild-type mice corresponding to the SCN shell and ventral core, high expression of PER was found at lights-off most likely representing an evening clock (E-clock). In another smaller cluster of neurons located in the central core of the SCN, PER expression peaks in antiphase at lights-on and could represent a morning clock (M-clock). BMAL1 immunoreactivity was found to be expressed in antiphase to PER in M and E neurons, respectively. PER was found in 98% of neurons expressing vasopressin (AVP) and in 92% of VIP neurons. The chemotype of M neurons was not identified. M but not E cells were responsive to long but not short photoperiods. The expression of the VPAC2 receptor was found in both M and E cells, and VPAC2-deficient mice displayed markedly blunted PER expression in both cell clusters of the SCN. Conclusion: These observations support the existence of M and E clocks involved in circadian and seasonal adaptation, which seem dependent on intact VIP/VPAC2 signaling in the SCN.
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Affiliation(s)
- Jens Hannibal
- Department of Clinical Biochemistry, Faculty of Health Sciences, Bispebjerg Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Tania H B Norn
- Department of Clinical Biochemistry, Faculty of Health Sciences, Bispebjerg Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Birgitte Georg
- Department of Clinical Biochemistry, Faculty of Health Sciences, Bispebjerg Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Jan Fahrenkrug
- Department of Clinical Biochemistry, Faculty of Health Sciences, Bispebjerg Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
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31
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Zhao J, Warman GR, Cheeseman JF. The functional changes of the circadian system organization in aging. Ageing Res Rev 2019; 52:64-71. [PMID: 31048031 DOI: 10.1016/j.arr.2019.04.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 04/14/2019] [Accepted: 04/24/2019] [Indexed: 01/12/2023]
Abstract
The circadian clock drives periodic oscillations at different levels of an organism from genes to behavior. This timing system is highly conserved across species from insects to mammals and human beings. The question of how the circadian clock is involved in the aging process continues to attract more attention. We aim to characterize the detrimental impact of aging on the circadian clock organization. We review studies on different components of the circadian clock at the central and periperal levels, and their changes in aged rodents and humans, and the fruit fly Drosophila. Intracellular signaling, cellular activity and intercellular coupling in the central pacemaker have been found to decline with advancing age. Evidence of degradation of the molecular clockwork reflected by clock gene expression in both central and peripheral oscillators due to aging is inadequate. The findings on age-associated molecular and functional changes of peripheral clocks are mixed. We conclude that aging can affect the circadian clock organization at various levels, and the impairment of the central network may be a fundamental mechanism of circadian disruption seen in aged species.
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32
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Kolbe I, Brehm N, Oster H. Interplay of central and peripheral circadian clocks in energy metabolism regulation. J Neuroendocrinol 2019; 31:e12659. [PMID: 30415480 DOI: 10.1111/jne.12659] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/01/2018] [Accepted: 11/05/2018] [Indexed: 12/11/2022]
Abstract
Metabolic health founds on a homeostatic balance that has to integrate the daily changes of rest/activity and feeding/fasting cycles. A network of endogenous 24-hour circadian clocks helps to anticipate daily recurring events and adjust physiology and behavioural functions accordingly. Circadian clocks are self-sustained cellular oscillators based on a set of clock genes/proteins organised in interlocked transcriptional-translational feedback loops. The body's clocks need to be regularly reset and synchronised with each other to achieve coherent rhythmic output signals. This synchronisation is achieved by interplay of a master clock, which resides in the suprachiasmatic nucleus, and peripheral tissue clocks. This clock network is reset by time signals such as the light/dark cycle, food intake and activity. The balanced interplay of clocks is easily disturbed in modern society by shiftwork or high-energy diets, which may further promote the development of metabolic disorders. In this review, we summarise the current model of central-peripheral clock interaction in metabolic health. Different established mouse models for central or peripheral clock disruption and their metabolic phenotypes are compared and the possible relevance of clock network interaction for the development of therapeutic approaches in humans is discussed.
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Affiliation(s)
- Isa Kolbe
- Institute of Neurobiology, University of Lubeck, Lubeck, Germany
| | - Niklas Brehm
- Institute of Neurobiology, University of Lubeck, Lubeck, Germany
| | - Henrik Oster
- Institute of Neurobiology, University of Lubeck, Lubeck, Germany
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33
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Weaver DR, van der Vinne V, Giannaris EL, Vajtay TJ, Holloway KL, Anaclet C. Functionally Complete Excision of Conditional Alleles in the Mouse Suprachiasmatic Nucleus by Vgat-ires-Cre. J Biol Rhythms 2019; 33:179-191. [PMID: 29671710 DOI: 10.1177/0748730418757006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mice with targeted gene disruption have provided important information about the molecular mechanisms of circadian clock function. A full understanding of the roles of circadian-relevant genes requires manipulation of their expression in a tissue-specific manner, ideally including manipulation with high efficiency within the suprachiasmatic nuclei (SCN). To date, conditional manipulation of genes within the SCN has been difficult. In a previously developed mouse line, Cre recombinase was inserted into the vesicular GABA transporter (Vgat) locus. Since virtually all SCN neurons are GABAergic, this Vgat-Cre line seemed likely to have high efficiency at disrupting conditional alleles in SCN. To test this premise, the efficacy of Vgat-Cre in excising conditional (fl, for flanked by LoxP) alleles in the SCN was examined. Vgat-Cre-mediated excision of conditional alleles of Clock or Bmal1 led to loss of immunostaining for products of the targeted genes in the SCN. Vgat-Cre+; Clockfl/fl; Npas2m/m mice and Vgat-Cre+; Bmal1fl/fl mice became arrhythmic immediately upon exposure to constant darkness, as expected based on the phenotype of mice in which these genes are disrupted throughout the body. The phenotype of mice with other combinations of Vgat-Cre+, conditional Clock, and mutant Npas2 alleles also resembled the corresponding whole-body knockout mice. These data indicate that the Vgat-Cre line is useful for Cre-mediated recombination within the SCN, making it useful for Cre-enabled technologies including gene disruption, gene replacement, and opto- and chemogenetic manipulation of the SCN circadian clock.
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Affiliation(s)
- David R Weaver
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts.,Graduate Program in Neuroscience, Graduate School of Biomedical Sciences, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Vincent van der Vinne
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - E Lela Giannaris
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts.,2. Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655
| | - Thomas J Vajtay
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Kristopher L Holloway
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts.,Graduate Program in Neuroscience, Graduate School of Biomedical Sciences, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Christelle Anaclet
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts.,Graduate Program in Neuroscience, Graduate School of Biomedical Sciences, University of Massachusetts Medical School, Worcester, Massachusetts
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34
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Li MT, Cao LH, Xiao N, Tang M, Deng B, Yang T, Yoshii T, Luo DG. Hub-organized parallel circuits of central circadian pacemaker neurons for visual photoentrainment in Drosophila. Nat Commun 2018; 9:4247. [PMID: 30315165 PMCID: PMC6185921 DOI: 10.1038/s41467-018-06506-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 08/20/2018] [Indexed: 12/20/2022] Open
Abstract
Circadian rhythms are orchestrated by a master clock that emerges from a network of circadian pacemaker neurons. The master clock is synchronized to external light/dark cycles through photoentrainment, but the circuit mechanisms underlying visual photoentrainment remain largely unknown. Here, we report that Drosophila has eye-mediated photoentrainment via a parallel pacemaker neuron organization. Patch-clamp recordings of central circadian pacemaker neurons reveal that light excites most of them independently of one another. We also show that light-responding pacemaker neurons send their dendrites to a neuropil called accessary medulla (aMe), where they make monosynaptic connections with Hofbauer–Buchner eyelet photoreceptors and interneurons that transmit compound-eye signals. Laser ablation of aMe and eye removal both abolish light responses of circadian pacemaker neurons, revealing aMe as a hub to channel eye inputs to central circadian clock. Taken together, we demonstrate that the central clock receives eye inputs via hub-organized parallel circuits in Drosophila. The central circadian clock in Drosophila is made up of ~ 150 anatomically distributed neurons; the circuits underlying photoentrainment is unclear. This study describes ex vivo patch-clamp recording of the eye-mediated light response of all known circadian clock neurons, and shows that they are organized in parallel circuits centered around a hub.
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Affiliation(s)
- Meng-Tong Li
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 100871, Beijing, China.,IDG/McGovern Institute for Brain Research, Peking University, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China.,PTN Graduate Program, College of Life Sciences, Peking University, 100871, Beijing, China
| | - Li-Hui Cao
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 100871, Beijing, China.,IDG/McGovern Institute for Brain Research, Peking University, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China.,Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China
| | - Na Xiao
- IDG/McGovern Institute for Brain Research, Peking University, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China.,Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China
| | - Min Tang
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 100871, Beijing, China.,IDG/McGovern Institute for Brain Research, Peking University, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China.,PTN Graduate Program, College of Life Sciences, Peking University, 100871, Beijing, China
| | - Bowen Deng
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China
| | - Tian Yang
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 100871, Beijing, China.,IDG/McGovern Institute for Brain Research, Peking University, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China
| | - Taishi Yoshii
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Dong-Gen Luo
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 100871, Beijing, China. .,IDG/McGovern Institute for Brain Research, Peking University, 100871, Beijing, China. .,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China. .,Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China.
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35
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Modeling clock-related metabolic syndrome due to conflicting light and food cues. Sci Rep 2018; 8:13641. [PMID: 30206243 PMCID: PMC6134130 DOI: 10.1038/s41598-018-31804-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/28/2018] [Indexed: 12/30/2022] Open
Abstract
Most organisms possess a light- and food- entrainable circadian clock system enabling their adaptation to daily environmental changes in sunlight and food availability. The mammalian circadian system is composed of multiple clocks throughout the body. These local clocks are entrained by nutrient, neural, endocrine and temperature cues and drive diverse physiological functions including metabolism. In particular, the clock of the pancreatic β cell rhythmically regulates the transcription of genes involved in glucose-stimulated insulin secretion. Perturbations of this fine-tuned oscillatory network increase the susceptibility to diseases. Besides chronic jet lag and shift work, common perturbations are ill-timed eating patterns which can lead to metabolic troubles (such as hypoinsulinemia). We have built a mathematical model describing the clock-dependent pancreatic regulation of glucose homeostasis in rodents. After calibrating the model using experimental data, we have investigated the effect of restricting food access to the normal rest phase. Our simulations show that the conflict between the light-dark cycle and the feeding-fasting cycle creates a differential phase shift in the expression of core clock genes (consistent with experimental observations). Our model further predicts that this induces a non-concomitance between nutrient cues and clock-controlled cues driving metabolic outputs which results in hypoinsulinemia, hyperglycemia as well as in a loss of food anticipation.
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36
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Cao R. mTOR Signaling, Translational Control, and the Circadian Clock. Front Genet 2018; 9:367. [PMID: 30250482 PMCID: PMC6139299 DOI: 10.3389/fgene.2018.00367] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/22/2018] [Indexed: 11/13/2022] Open
Abstract
Almost all cellular processes are regulated by the approximately 24 h rhythms that are endogenously driven by the circadian clock. mRNA translation, as the most energy consuming step in gene expression, is temporally controlled by circadian rhythms. Recent research has uncovered key mechanisms of translational control that are orchestrated by circadian rhythmicity and in turn feed back to the clock machinery to maintain robustness and accuracy of circadian timekeeping. Here I review recent progress in our understanding of translation control mechanisms in the circadian clock, focusing on a role for the mammalian/mechanistic target of rapamycin (mTOR) signaling pathway in modulating entrainment, synchronization and autonomous oscillation of circadian clocks. I also discuss the relevance of circadian mTOR functions in disease.
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Affiliation(s)
- Ruifeng Cao
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, United States.,Department of Neuroscience, University of Minnesota Medical School, Minneapolis, MN, United States
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37
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Bedont JL, Rohr KE, Bathini A, Hattar S, Blackshaw S, Sehgal A, Evans JA. Asymmetric vasopressin signaling spatially organizes the master circadian clock. J Comp Neurol 2018; 526:2048-2067. [PMID: 29931690 DOI: 10.1002/cne.24478] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 05/07/2018] [Accepted: 03/12/2018] [Indexed: 01/04/2023]
Abstract
The suprachiasmatic nucleus (SCN) is the neural network that drives daily rhythms in behavior and physiology. The SCN encodes environmental changes through the phasing of cellular rhythms across its anteroposterior axis, but it remains unknown what signaling mechanisms regulate clock function along this axis. Here we demonstrate that arginine vasopressin (AVP) signaling organizes the SCN into distinct anteroposterior domains. Spatial mapping of SCN gene expression using in situ hybridization delineated anterior and posterior domains for AVP signaling components, including complementary patterns of V1a and V1b expression that suggest different roles for these two AVP receptors. Similarly, anteroposterior patterning of transcripts involved in Vasoactive Intestinal Polypeptide- and Prokineticin2 signaling was evident across the SCN. Using bioluminescence imaging, we then revealed that inhibiting V1A and V1B signaling alters period and phase differentially along the anteroposterior SCN. V1 antagonism lengthened period the most in the anterior SCN, whereas changes in phase were largest in the posterior SCN. Further, separately antagonizing V1A and V1B signaling modulated SCN function in a manner that mapped onto anteroposterior expression patterns. Lastly, V1 antagonism influenced SCN period and phase along the dorsoventral axis, complementing effects on the anteroposterior axis. Together, these results indicate that AVP signaling modulates SCN period and phase in a spatially specific manner, which is expected to influence how the master clock interacts with downstream tissues and responds to environmental changes. More generally, we reveal anteroposterior asymmetry in neuropeptide signaling as a recurrent organizational motif that likely influences neural computations in the SCN clock network.
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Affiliation(s)
- Joseph L Bedont
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania.,Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21218
| | - Kayla E Rohr
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, 53233
| | - Abhijith Bathini
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21218
| | - Samer Hattar
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Department of Biology, Johns Hopkins University, Baltimore, MD, 21218
| | - Seth Blackshaw
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Center for Human Systems Biology, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21218
| | - Amita Sehgal
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania
| | - Jennifer A Evans
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, 53233
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Chatterjee A, Lamaze A, De J, Mena W, Chélot E, Martin B, Hardin P, Kadener S, Emery P, Rouyer F. Reconfiguration of a Multi-oscillator Network by Light in the Drosophila Circadian Clock. Curr Biol 2018; 28:2007-2017.e4. [PMID: 29910074 PMCID: PMC6039274 DOI: 10.1016/j.cub.2018.04.064] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/28/2018] [Accepted: 04/18/2018] [Indexed: 01/02/2023]
Abstract
The brain clock that drives circadian rhythms of locomotor activity relies on a multi-oscillator neuronal network. In addition to synchronizing the clock with day-night cycles, light also reformats the clock-driven daily activity pattern. How changes in lighting conditions modify the contribution of the different oscillators to remodel the daily activity pattern remains largely unknown. Our data in Drosophila indicate that light readjusts the interactions between oscillators through two different modes. We show that a morning s-LNv > DN1p circuit works in series, whereas two parallel evening circuits are contributed by LNds and other DN1ps. Based on the photic context, the master pacemaker in the s-LNv neurons swaps its enslaved partner-oscillator-LNd in the presence of light or DN1p in the absence of light-to always link up with the most influential phase-determining oscillator. When exposure to light further increases, the light-activated LNd pacemaker becomes independent by decoupling from the s-LNvs. The calibration of coupling by light is layered on a clock-independent network interaction wherein light upregulates the expression of the PDF neuropeptide in the s-LNvs, which inhibits the behavioral output of the DN1p evening oscillator. Thus, light modifies inter-oscillator coupling and clock-independent output-gating to achieve flexibility in the network. It is likely that the light-induced changes in the Drosophila brain circadian network could reveal general principles of adapting to varying environmental cues in any neuronal multi-oscillator system.
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Affiliation(s)
- Abhishek Chatterjee
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Angélique Lamaze
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Joydeep De
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Wilson Mena
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Elisabeth Chélot
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Béatrice Martin
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Paul Hardin
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77845-3258, USA
| | | | - Patrick Emery
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - François Rouyer
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France.
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Cooper JM, Halter KA, Prosser RA. Circadian rhythm and sleep-wake systems share the dynamic extracellular synaptic milieu. Neurobiol Sleep Circadian Rhythms 2018; 5:15-36. [PMID: 31236509 PMCID: PMC6584685 DOI: 10.1016/j.nbscr.2018.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/06/2018] [Accepted: 04/10/2018] [Indexed: 01/23/2023] Open
Abstract
The mammalian circadian and sleep-wake systems are closely aligned through their coordinated regulation of daily activity patterns. Although they differ in their anatomical organization and physiological processes, they utilize overlapping regulatory mechanisms that include an assortment of proteins and molecules interacting within the extracellular space. These extracellular factors include proteases that interact with soluble proteins, membrane-attached receptors and the extracellular matrix; and cell adhesion molecules that can form complex scaffolds connecting adjacent neurons, astrocytes and their respective intracellular cytoskeletal elements. Astrocytes also participate in the dynamic regulation of both systems through modulating neuronal appositions, the extracellular space and/or through release of gliotransmitters that can further contribute to the extracellular signaling processes. Together, these extracellular elements create a system that integrates rapid neurotransmitter signaling across longer time scales and thereby adjust neuronal signaling to reflect the daily fluctuations fundamental to both systems. Here we review what is known about these extracellular processes, focusing specifically on areas of overlap between the two systems. We also highlight questions that still need to be addressed. Although we know many of the extracellular players, far more research is needed to understand the mechanisms through which they modulate the circadian and sleep-wake systems.
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Key Words
- ADAM, A disintegrin and metalloproteinase
- AMPAR, AMPA receptor
- Astrocytes
- BDNF, brain-derived neurotrophic factor
- BMAL1, Brain and muscle Arnt-like-1 protein
- Bmal1, Brain and muscle Arnt-like-1 gene
- CAM, cell adhesion molecules
- CRY, cryptochrome protein
- Cell adhesion molecules
- Circadian rhythms
- Cry, cryptochrome gene
- DD, dark-dark
- ECM, extracellular matrix
- ECS, extracellular space
- EEG, electroencephalogram
- Endo N, endoneuraminidase N
- Extracellular proteases
- GFAP, glial fibrillary acidic protein
- IL, interleukin
- Ig, immunoglobulin
- LC, locus coeruleus
- LD, light-dark
- LH, lateral hypothalamus
- LRP-1, low density lipoprotein receptor-related protein 1
- LTP, long-term potentiation
- MMP, matrix metalloproteinases
- NCAM, neural cell adhesion molecule protein
- NMDAR, NMDA receptor
- NO, nitric oxide
- NST, nucleus of the solitary tract
- Ncam, neural cell adhesion molecule gene
- Nrl, neuroligin gene
- Nrx, neurexin gene
- P2, purine type 2 receptor
- PAI-1, plasminogen activator inhibitor-1
- PER, period protein
- PPT, peduculopontine tegmental nucleus
- PSA, polysialic acid
- Per, period gene
- REMS, rapid eye movement sleep
- RSD, REM sleep disruption
- SCN, suprachiasmatic nucleus
- SWS, slow wave sleep
- Sleep-wake system
- Suprachiasmatic nucleus
- TNF, tumor necrosis factor
- TTFL, transcriptional-translational negative feedback loop
- VIP, vasoactive intestinal polypeptide
- VLPO, ventrolateral preoptic
- VP, vasopressin
- VTA, ventral tegmental area
- dNlg4, drosophila neuroligin-4 gene
- nNOS, neuronal nitric oxide synthase gene
- nNOS, neuronal nitric oxide synthase protein
- tPA, tissue-type plasminogen activator
- uPA, urokinase-type plasminogen activator
- uPAR, uPA receptor
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Abstract
The kidneys regulate many vital functions that require precise control throughout the day. These functions, such as maintaining sodium balance or regulating arterial pressure, rely on an intrinsic clock mechanism that was commonly believed to be controlled by the central nervous system. Mounting evidence in recent years has unveiled previously underappreciated depth of influence by circadian rhythms and clock genes on renal function, at the molecular and physiological level, independent of other external factors. The impact of circadian rhythms in the kidney also affects individuals from a clinical standpoint, as the loss of rhythmic activity or clock gene expression have been documented in various cardiovascular diseases. Fortunately, the prognostic value of examining circadian rhythms may prove useful in determining the progression of a kidney-related disease, and chronotherapy is a clinical intervention that requires consideration of circadian and diurnal rhythms in the kidney. In this review, we discuss evidence of circadian regulation in the kidney from basic and clinical research in order to provide a foundation on which a great deal of future research is needed to expand our understanding of circadian relevant biology.
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Affiliation(s)
- Jermaine G Johnston
- Section of Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - David M Pollock
- Section of Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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Young AJ. The role of telomeres in the mechanisms and evolution of life-history trade-offs and ageing. Philos Trans R Soc Lond B Biol Sci 2018; 373:20160452. [PMID: 29335379 PMCID: PMC5784072 DOI: 10.1098/rstb.2016.0452] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2017] [Indexed: 12/16/2022] Open
Abstract
Evolutionary biology and biomedicine have seen a surge of recent interest in the possibility that telomeres play a role in life-history trade-offs and ageing. Here, I evaluate alternative hypotheses for the role of telomeres in the mechanisms and evolution of life-history trade-offs and ageing, and highlight outstanding challenges. First, while recent findings underscore the possibility of a proximate causal role for telomeres in current-future trade-offs and ageing, it is currently unclear (i) whether telomeres ever play a causal role in either and (ii) whether any causal role for telomeres arises via shortening or length-independent mechanisms. Second, I consider why, if telomeres do play a proximate causal role, selection has not decoupled such a telomere-mediated trade-off between current and future performance. Evidence suggests that evolutionary constraints have not rendered such decoupling impossible. Instead, a causal role for telomeres would more plausibly reflect an adaptive strategy, born of telomere maintenance costs and/or a function for telomere attrition (e.g. in countering cancer), the relative importance of which is currently unclear. Finally, I consider the potential for telomere biology to clarify the constraints at play in life-history evolution, and to explain the form of the current-future trade-offs and ageing trajectories that we observe today.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.
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Affiliation(s)
- Andrew J Young
- School of Biosciences, University of Exeter Penryn Campus, Penryn TR10 9FE, UK
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42
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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: 23] [Impact Index Per Article: 3.8] [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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Abstract
Importance of the neuroendocrine brain for health and happiness has become clear since the 1960s. Foundations laid 100 years ago culminated in Geoffrey W Harris's model of control by the brain of secretion of anterior and posterior pituitary gland hormones through, respectively, releasing factors secreted into the hypothalamic-hypophysial portal system, and directly from axon terminals into the systemic circulation. Confirmation, expansion and deepening of knowledge and understanding have followed increasingly sophisticated technology. This allowed chemical characterisation of the posterior pituitary hormones, oxytocin and vasopressin, the releasing factors, their receptors and genes, location of the neurosecretory neurons in the hypothalamus, and how their activity is controlled, including by neural and hormonal feedback, and how hormone rhythms are generated. Wider roles of these neurons and their peptides in the brain are now recognised: in reproductive and social behaviours, emotions and appetite. Plasticity and epigenetic programming of neuroendocrine systems have emerged as important features.
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Affiliation(s)
- John A. Russell
- Professor Emeritus, Edinburgh Medical School: Biomedical Sciences, College of Medicine and Veterinary Medicine, University of Edinburgh, UK
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44
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Impact of Time-Restricted Feeding and Dawn-to-Sunset Fasting on Circadian Rhythm, Obesity, Metabolic Syndrome, and Nonalcoholic Fatty Liver Disease. Gastroenterol Res Pract 2017; 2017:3932491. [PMID: 29348746 PMCID: PMC5733887 DOI: 10.1155/2017/3932491] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 10/01/2017] [Accepted: 10/12/2017] [Indexed: 12/13/2022] Open
Abstract
Obesity now affects millions of people and places them at risk of developing metabolic syndrome, nonalcoholic fatty liver disease (NAFLD), and even hepatocellular carcinoma. This rapidly emerging epidemic has led to a search for cost-effective methods to prevent the metabolic syndrome and NAFLD as well as the progression of NAFLD to cirrhosis and hepatocellular carcinoma. In murine models, time-restricted feeding resets the hepatic circadian clock and enhances transcription of key metabolic regulators of glucose and lipid homeostasis. Studies of the effect of dawn-to-sunset Ramadan fasting, which is akin to time-restricted feeding model, have also identified significant improvement in body mass index, serum lipid profiles, and oxidative stress parameters. Based on the findings of studies conducted on human subjects, dawn-to-sunset fasting has the potential to be a cost-effective intervention for obesity, metabolic syndrome, and NAFLD.
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45
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Duhart JM, Brocardo L, Caldart CS, Marpegan L, Golombek DA. Circadian Alterations in a Murine Model of Hypothalamic Glioma. Front Physiol 2017; 8:864. [PMID: 29163208 PMCID: PMC5670357 DOI: 10.3389/fphys.2017.00864] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/16/2017] [Indexed: 01/09/2023] Open
Abstract
The mammalian circadian system is controlled by a central oscillator located in the suprachiasmatic nuclei (SCN) of the hypothalamus, in which glia appears to play a prominent role. Gliomas originate from glial cells and are the primary brain tumors with the highest incidence and mortality. Optic pathway/hypothalamic gliomas account for 4–7% of all pediatric intracranial tumors. Given the anatomical location, which compromises both the circadian pacemaker and its photic input pathway, we decided to study whether the presence of gliomas in the hypothalamic region could alter circadian behavioral outputs. Athymic nude mice implanted with LN229 human glioma cells showed an increase in the endogenous period of the circadian clock, which was also less robust in terms of sustaining the free running period throughout 2 weeks of screening. We also found that implanted mice showed a slower resynchronization rate after an abrupt 6 h advance of the light-dark (LD) cycle, advanced phase angle, and a decreased direct effect of light in general activity (masking), indicating that hypothalamic tumors could also affect photic sensitivity of the circadian clock. Our work suggests that hypothalamic gliomas have a clear impact both on the endogenous pacemaking of the circadian system, as well as on the photic synchronization of the clock. These findings strongly suggest that the observation of altered circadian parameters in patients might be of relevance for glioma diagnosis.
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Affiliation(s)
- José M Duhart
- Laboratorio de Cronobiología, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - Lucila Brocardo
- Laboratorio de Cronobiología, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - Carlos S Caldart
- Laboratorio de Cronobiología, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - Luciano Marpegan
- Laboratorio de Cronobiología, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - Diego A Golombek
- Laboratorio de Cronobiología, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Buenos Aires, Argentina
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Park JS, Cederroth CR, Basinou V, Sweetapple L, Buijink R, Lundkvist GB, Michel S, Canlon B. Differential Phase Arrangement of Cellular Clocks along the Tonotopic Axis of the Mouse Cochlea Ex Vivo. Curr Biol 2017; 27:2623-2629.e2. [PMID: 28823676 PMCID: PMC6899219 DOI: 10.1016/j.cub.2017.07.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/15/2017] [Accepted: 07/07/2017] [Indexed: 12/18/2022]
Abstract
Topological distributions of individual cellular clocks have not been demonstrated in peripheral organs. The cochlea displays circadian patterns of core clock gene expression [1, 2]. PER2 protein is expressed in the hair cells and spiral ganglion neurons of the cochlea in the spiral ganglion neurons [1]. To investigate the topological organization of cellular oscillators in the cochlea, we recorded circadian rhythms from mouse cochlear explants using highly sensitive real-time tracking of PER2::LUC bioluminescence. Here, we show cell-autonomous and self-sustained oscillations originating from hair cells and spiral ganglion neurons. Multi-phased cellular clocks were arranged along the length of the cochlea with oscillations initiating at the apex (low-frequency region) and traveling toward the base (high-frequency region). Phase differences of 3 hr were found between cellular oscillators in the apical and middle regions and from isolated individual cochlear regions, indicating that cellular networks organize the rhythms along the tonotopic axis. This is the first demonstration of a spatiotemporal arrangement of circadian clocks at the cellular level in a peripheral organ. Cochlear rhythms were disrupted in the presence of either voltage-gated potassium channel blocker (TEA) or extracellular calcium chelator (BAPTA), demonstrating that multiple types of ion channels contribute to the maintenance of coherent rhythms. In contrast, preventing action potentials with tetrodotoxin (TTX) or interfering with cell-to-cell communication the broad-spectrum gap junction blocker (CBX [carbenoxolone]) had no influence on cochlear rhythms. These findings highlight a dynamic regulation and longitudinal distribution of cellular clocks in the cochlea.
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Affiliation(s)
- Jung-Sub Park
- Department of Physiology and Pharmacology, Karolinska Institutet, 17177 Stockholm, Sweden; Department of Otolaryngology, Ajou University School of Medicine, 164 Worldcup-ro, Yeongtong-gu, Suwon 16499, Korea
| | | | - Vasiliki Basinou
- Department of Physiology and Pharmacology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Lara Sweetapple
- Department of Physiology and Pharmacology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Renate Buijink
- Department of Molecular Cell Biology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Gabriella B Lundkvist
- Department of Physiology and Pharmacology, Karolinska Institutet, 17177 Stockholm, Sweden; Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden; Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Stephan Michel
- Department of Molecular Cell Biology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Barbara Canlon
- Department of Physiology and Pharmacology, Karolinska Institutet, 17177 Stockholm, Sweden.
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Yoshikawa T, Inagaki NF, Takagi S, Kuroda S, Yamasaki M, Watanabe M, Honma S, Honma KI. Localization of photoperiod responsive circadian oscillators in the mouse suprachiasmatic nucleus. Sci Rep 2017; 7:8210. [PMID: 28811515 PMCID: PMC5557852 DOI: 10.1038/s41598-017-08186-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 07/07/2017] [Indexed: 11/09/2022] Open
Abstract
The circadian pacemaker in the suprachiasmatic nucleus (SCN) yields photoperiodic response to transfer seasonal information to physiology and behavior. To identify the precise location involved in photoperiodic response in the SCN, we analyzed circadian Period1 and PERIOD2 rhythms in horizontally sectioned SCN of mice exposed to a long or short day. Statistical analyses of bioluminescence images with respective luciferase reporters on pixel level enabled us to identify the distinct localization of three oscillating regions; a large open-ring-shape region, the region at the posterior end and a sharply demarcated oval region at the center of the SCN. The first two regions are the respective sites for the so-called evening and morning oscillators, and the third region is possibly a site for mediating photic signals to the former oscillators. In these regions, there are two classes of oscillating cells in which Per1 and Per2 could play differential roles in photoperiodic responses.
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Affiliation(s)
- Tomoko Yoshikawa
- Photonic Bioimaging Section, Hokkaido University Graduate School of Medicine, Sapporo, Japan. .,Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan. .,Department of Anatomy and Neurobiology, Kindai University Faculty of Medicine, Osaka-sayama, Japan.
| | - Natsuko F Inagaki
- Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Seiji Takagi
- Department of Complex and Intelligent Systems, Future University Hakodate, Hakodate, Japan
| | - Shigeru Kuroda
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan
| | - Miwako Yamasaki
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Sato Honma
- Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan. .,Research and Education Center for Brain Science, Hokkaido University, Sapporo, Japan.
| | - Ken-Ichi Honma
- Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
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Delayed Cryptochrome Degradation Asymmetrically Alters the Daily Rhythm in Suprachiasmatic Clock Neuron Excitability. J Neurosci 2017; 37:7824-7836. [PMID: 28698388 PMCID: PMC5559760 DOI: 10.1523/jneurosci.0691-17.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/01/2017] [Accepted: 06/08/2017] [Indexed: 11/30/2022] Open
Abstract
Suprachiasmatic nuclei (SCN) neurons contain an intracellular molecular circadian clock and the Cryptochromes (CRY1/2), key transcriptional repressors of this molecular apparatus, are subject to post-translational modification through ubiquitination and targeting for proteosomal degradation by the ubiquitin E3 ligase complex. Loss-of-function point mutations in a component of this ligase complex, Fbxl3, delay CRY1/2 degradation, reduce circadian rhythm strength, and lengthen the circadian period by ∼2.5 h. The molecular clock drives circadian changes in the membrane properties of SCN neurons, but it is unclear how alterations in CRY1/2 stability affect SCN neurophysiology. Here we use male and female Afterhours mice which carry the circadian period lengthening loss-of-function Fbxl3Afh mutation and perform patch-clamp recordings from SCN brain slices across the projected day/night cycle. We find that the daily rhythm in membrane excitability in the ventral SCN (vSCN) was enhanced in amplitude and delayed in timing in Fbxl3Afh/Afh mice. At night, vSCN cells from Fbxl3Afh/Afh mice were more hyperpolarized, receiving more GABAergic input than their Fbxl3+/+ counterparts. Unexpectedly, the progression to daytime hyperexcited states was slowed by Afh mutation, whereas the decline to hypoexcited states was accelerated. In long-term bioluminescence recordings, GABAA receptor blockade desynchronized the Fbxl3+/+ but not the Fbxl3Afh/Afh vSCN neuronal network. Further, a neurochemical mimic of the light input pathway evoked larger shifts in molecular clock rhythms in Fbxl3Afh/Afh compared with Fbxl3+/+ SCN slices. These results reveal unanticipated consequences of delaying CRY degradation, indicating that the Afh mutation prolongs nighttime hyperpolarized states of vSCN cells through increased GABAergic synaptic transmission. SIGNIFICANCE STATEMENT The intracellular molecular clock drives changes in SCN neuronal excitability, but it is unclear how mutations affecting post-translational modification of molecular clock proteins influence the temporal expression of SCN neuronal state or intercellular communication within the SCN network. Here we show for the first time, that a mutation that prolongs the stability of key components of the intracellular clock, the cryptochrome proteins, unexpectedly increases in the expression of hypoexcited neuronal state in the ventral SCN at night and enhances hyperpolarization of ventral SCN neurons at this time. This is accompanied by increased GABAergic signaling and by enhanced responsiveness to a neurochemical mimic of the light input pathway to the SCN. Therefore, post-translational modification shapes SCN neuronal state and network properties.
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Circadian Rhythms in Fear Conditioning: An Overview of Behavioral, Brain System, and Molecular Interactions. Neural Plast 2017; 2017:3750307. [PMID: 28698810 PMCID: PMC5494081 DOI: 10.1155/2017/3750307] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/28/2017] [Accepted: 05/14/2017] [Indexed: 12/17/2022] Open
Abstract
The formation of fear memories is a powerful and highly evolutionary conserved mechanism that serves the behavioral adaptation to environmental threats. Accordingly, classical fear conditioning paradigms have been employed to investigate fundamental molecular processes of memory formation. Evidence suggests that a circadian regulation mechanism allows for a timestamping of such fear memories and controlling memory salience during both their acquisition and their modification after retrieval. These mechanisms include an expression of molecular clocks in neurons of the amygdala, hippocampus, and medial prefrontal cortex and their tight interaction with the intracellular signaling pathways that mediate neural plasticity and information storage. The cellular activities are coordinated across different brain regions and neural circuits through the release of glucocorticoids and neuromodulators such as acetylcholine, which integrate circadian and memory-related activation. Disturbance of this interplay by circadian phase shifts or traumatic experience appears to be an important factor in the development of stress-related psychopathology, considering these circadian components are of critical importance for optimizing therapeutic approaches to these disorders.
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Temporal Regulation of GABA A Receptor Subunit Expression: Role in Synaptic and Extrasynaptic Communication in the Suprachiasmatic Nucleus. eNeuro 2017; 4:eN-NWR-0352-16. [PMID: 28466071 PMCID: PMC5411165 DOI: 10.1523/eneuro.0352-16.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 04/11/2017] [Accepted: 04/12/2017] [Indexed: 11/21/2022] Open
Abstract
Recent molecular studies suggest that the expression levels of δ and γ2 GABAA receptor (GABAAR) subunits regulate the balance between synaptic and extrasynaptic GABA neurotransmission in multiple brain regions. We investigated the expression of GABAAδ and GABAAγ2 and the functional significance of a change in balance between these subunits in a robust local GABA network contained within the suprachiasmatic nucleus of the hypothalamus (SCN). Muscimol, which can activate both synaptic and extrasynaptic GABAARs, injected into the SCN during the day phase advanced the circadian pacemaker, whereas injection of the extrasynaptic GABAA superagonist 4,5,6,7-tetrahydroisoxazolo(5,4-c)pyridin-3-ol (THIP) had no effect on circadian phase. In contrast, injection of either THIP or muscimol during the night was sufficient to block the phase shifting effects of light. Gene expression analysis of the whole SCN revealed different temporal patterns in GABAAδ and GABAAγ2 mRNA expression. When examined across all subregions of the SCN, quantitative immunohistochemical analysis found no significant variations in GABAAδ protein immunoreactivity (IR) but did find significant variations in GABAAγ2 protein-IR in hamsters housed in either LD cycles or in constant darkness. Remarkably, significant interactions in the ratio of GABAAδ:GABAAγ2 subunits between lighting condition and circadian phase occurred only within one highly discrete anatomical area of the SCN; a region that functions as the input for lighting information from the retina. Taken together, these data support the hypothesis that the balance between synaptic and extrasynaptic GABAARs determines the functional response to GABA, and that this balance is differentially regulated in a region-specific manner.
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