Disruption of the Suprachiasmatic Nucleus Blunts a Time of Day-Dependent Variation in Systemic Anaphylactic Reaction in Mice

Anaphylaxis is a severe systemic allergic reaction which is rapid in onset and potentially fatal, caused by excessive release of mediators including histamine and cytokines/chemokines from mast cells and basophils upon allergen/IgE stimulation. Increased prevalence of anaphylaxis in industrialized countries requires urgent needs for better understanding of anaphylaxis. However, the pathophysiology of the disease is not fully understood. Here we report that the circadian clock may be an important regulator of anaphylaxis. In mammals, the central clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus synchronizes and entrains peripheral circadian clock present in virtually all cell types via neural and endocrine pathways, thereby driving the daily rhythms in behavior and physiology. We found that mechanical disruption of the SCN resulted in the absence of a time of day-dependent variation in passive systemic anaphylactic (PSA) reaction in mice, associated with loss of daily variations in serum histamine, MCP-1 (CCL2), and IL-6 levels. These results suggest that the central SCN clock controls the time of day-dependent variation in IgE-mediated systemic anaphylactic reaction, which may provide a novel insight into the pathophysiology of anaphylaxis.

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A54 THE CIRCADIAN CLOCK INFLUENCES JAK/STAT SIGNALING AND GUT PERMEABILITY

Journal of the Canadian Association of Gastroenterology ◽

10.1093/jcag/gwab002.052 ◽

2021 ◽

Vol 4 (Supplement_1) ◽

pp. 11-12

Author(s):

K Parasram ◽

D Bachetti ◽

P Karpowicz

Keyword(s):

Circadian Clock ◽

Clock Cycle ◽

Intestinal Barrier ◽

Fruit Fly ◽

Cell Types ◽

Time Of Day ◽

Acute Injury ◽

Intestinal Barrier Function ◽

Intestinal Immunity ◽

Stat Signaling

Abstract Background The circadian clock is a 24-hour feedback loop that drives rhythms in behaviours and physiological processes. This molecular timekeeper consists of the transcription factors, Clock-Cycle, that drive expression of thousands of clock-controlled genes, with two of these, Period and Timeless, acting as negative regulators of Clock-Cycle. This fundamental mechanism was initially characterized in the fruit fly, Drosophila melanogaster (Nobel Prize in Physiology & Medicine, 2017), and is highly conserved in humans. The intestine, or midgut, of Drosophila, is also similar to the human small intestine consisting of similar cellular lineage, signaling pathways, and physiological functions. The lineage of the Drosophila intestine contains the same four cell types as humans: intestinal stem cells (ISCs), progenitors called enteroblasts, enterocytes and enteroendocrine cells. This simplified lineage as well as the genetic tools available, make Drosophila an ideal model for intestinal regeneration in health and disease. We have previously shown that the circadian clock is active in ISCs, EBs and ECs during both homeostatic and regenerating conditions. Furthermore, the circadian clock regulates the mitosis of ISCs under regenerating conditions. Aims We sought to uncover if Jak/STAT signaling, one of the key pathways involved in ISC proliferation in the Drosophila intestine, shows a circadian rhythm and if there is a time-of-day difference in the regenerative response. Methods To test whether the clock regulates Jak/STAT during acute injury, we developed an irradiation assay that does not affect survival but acutely disrupts intestinal barrier function. Results Using a dynamic reporter of Jak/STAT activity we show that Period circadian clock mutants have low Jak/STAT signaling and a leaky gut phenotype. Wildtype controls show time-dependent gut leakiness upon irradiation, which is higher and time-independent in Period mutants. The level of Jak/STAT response differs depending on the time of irradiation in the controls, but is higher at all times in the mutants. Conclusions The Jak/Stat pathway regulates intestinal immunity and epithelial cell proliferation in humans, thus playing a role in colorectal cancer and inflammatory bowel disease. Our results suggest Jak/Stat is controlled by the circadian clock, which has implications for intestinal recovery following medical treatments, including radiation therapy. Funding Agencies NRC

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The Development and Decay of the Circadian Clock in Drosophila melanogaster

Clocks & Sleep ◽

10.3390/clockssleep1040037 ◽

2019 ◽

Vol 1 (4) ◽

pp. 489-500

Author(s):

Jia Zhao ◽

Guy Warman ◽

James Cheeseman

Keyword(s):

Circadian Clock ◽

Clock Genes ◽

Firefly Luciferase ◽

Whole Body ◽

Drosophila Model ◽

Central Clock ◽

Development And Aging ◽

Central Oscillator ◽

The Brain ◽

Insight Into

The way in which the circadian clock mechanism develops and decays throughout life is interesting for a number of reasons and may give us insight into the process of aging itself. The Drosophila model has been proven invaluable for the study of the circadian clock and development and aging. Here we review the evidence for how the Drosophila clock develops and changes throughout life, and present a new conceptual model based on the results of our recent work. Firefly luciferase lines faithfully report the output of known clock genes at the central clock level in the brain and peripherally throughout the whole body. Our results show that the clock is functioning in embryogenesis far earlier than previously thought. This central clock in the fly remains robust throughout the life of the animal and only degrades immediately prior to death. However, at the peripheral (non-central oscillator level) the clock shows weakened output as the animal ages, suggesting the possibility of the breakdown in the cohesion of the circadian network.

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Time-of-Day- and Light-Dependent Expression of Ubiquitin Protein Ligase E3 Component N-Recognin 4 (UBR4) in the Suprachiasmatic Nucleus Circadian Clock

PLoS ONE ◽

10.1371/journal.pone.0103103 ◽

2014 ◽

Vol 9 (8) ◽

pp. e103103 ◽

Cited By ~ 4

Author(s):

Harrod H. Ling ◽

Christian Beaulé ◽

Cheng-Kang Chiang ◽

Ruijun Tian ◽

Daniel Figeys ◽

...

Keyword(s):

Circadian Clock ◽

Suprachiasmatic Nucleus ◽

Time Of Day ◽

Ubiquitin Protein Ligase

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RDNA-04. CIRCADIAN RHYTHMS AND RADIATION CHRONOTHERAPY IN GLIOBLASTOMA CELL LINES AND CENTRAL NERVOUS SYSTEM CELL CONTROLS

Neuro-Oncology ◽

10.1093/neuonc/noz175.864 ◽

2019 ◽

Vol 21 (Supplement_6) ◽

pp. vi207-vi207 ◽

Cited By ~ 1

Author(s):

Dorela Shuboni-Mulligan ◽

Madeline Dahut ◽

Demarrius Young ◽

Mark Gilbert ◽

Terri Armstrong

Keyword(s):

Circadian Rhythms ◽

Circadian Clock ◽

Cell Lines ◽

Cell Types ◽

Radiation Sensitivity ◽

Cranial Irradiation ◽

Time Of Day ◽

Tissue Type ◽

Lower Sensitivity

Abstract BACKGROUND Chronotherapy is the optimally timed administration of treatment based on the circadian clock. In non-CNS cancers, circadian rhythms (CR) drive the expression of mechanisms responsible for radiation sensitivity and associated toxicity. Our previous work has shown that cranial irradiation in GBM patients produces a high incidence of hypersomnolence and susceptibility is linked to circadian clock gene polymorphisms. This study determined if CR can be demonstrated using in vitro GBM and CNS cells and then if sensitivity to radiation is circadian time and tissue dependent. METHODS Rat GBM, fibroblasts, and suprachiasmatic nucleus (SCN) cells were used and compared to human U251 GBM cells. Cells were synchronized using the serum shook method; protein levels for PER2 expression over 24 hr in 4 hr intervals were quantified to confirm CR. Colony formation and 3D invasion assays after radiation (0-8Gy or 8Gy, respectively) 8 and 20 hrs after synchronization were evaluated. RESULTS All cell types demonstrated CR by PER2 expression (trough ~8hr post (CT8); peak ~20hrs post (CT20)). In rat, GBM (LD50 = 4Gy) and SCN cells (LD50 =5 Gy) showed lower sensitivity than fibroblasts (LD50= 2 Gy). Human U251 GBM cells had similar radiation sensitivity to rat GBM. Time-of-day effects were dependent on tissue type with both rat and human GBM cell lines more affected by radiation at CT20, with less invasion (CT20:-35488.5±2622.1 vs CT8:-23160.5±3273.4µm) and survival in the colony assay (F(1,71)=4.105,p< 0.05). Conversely, SCN cells which drive sleep-wake, showed the converse with greater effect at the 8hr compared with 20hr (F(1, 35)=19.93,p< 0.001). CONCLUSIONS These data suggest that timing of radiation could be optimized to improve detrimental effects on healthy tissue, while still providing effective intra-tumor doses. In future studies, we will interrogate the mechanisms driving time-of-day effects in cells and test radiation chronotherapy in our radiation-induced hypersomnolence mouse model.

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Collective timekeeping among cells of the master circadian clock

Journal of Endocrinology ◽

10.1530/joe-16-0054 ◽

2016 ◽

Vol 230 (1) ◽

pp. R27-R49 ◽

Cited By ~ 36

Author(s):

Jennifer A Evans

Keyword(s):

Circadian Clock ◽

Recent Progress ◽

Cell Types ◽

Tissue Level ◽

Functional Roles ◽

Network Function ◽

Signaling Mechanisms ◽

Distinct Cell ◽

Hypothalamic Nuclei ◽

Insight Into

The suprachiasmatic nucleus (SCN) of the anterior hypothalamus is the master circadian clock that coordinates daily rhythms in behavior and physiology in mammals. Like other hypothalamic nuclei, the SCN displays an impressive array of distinct cell types characterized by differences in neurotransmitter and neuropeptide expression. Individual SCN neurons and glia are able to display self-sustained circadian rhythms in cellular function that are regulated at the molecular level by a 24h transcriptional–translational feedback loop. Remarkably, SCN cells are able to harmonize with one another to sustain coherent rhythms at the tissue level. Mechanisms of cellular communication in the SCN network are not completely understood, but recent progress has provided insight into the functional roles of several SCN signaling factors. This review discusses SCN organization, how intercellular communication is critical for maintaining network function, and the signaling mechanisms that play a role in this process. Despite recent progress, our understanding of SCN circuitry and coupling is far from complete. Further work is needed to map SCN circuitry fully and define the signaling mechanisms that allow for collective timekeeping in the SCN network.

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A Catalog of GAL4 Drivers for Labeling and Manipulating Circadian Clock Neurons in Drosophila melanogaster

Journal of Biological Rhythms ◽

10.1177/0748730419895154 ◽

2019 ◽

Vol 35 (2) ◽

pp. 207-213 ◽

Cited By ~ 4

Author(s):

Manabu Sekiguchi ◽

Kotaro Inoue ◽

Tian Yang ◽

Dong-Gen Luo ◽

Taishi Yoshii

Keyword(s):

Drosophila Melanogaster ◽

Circadian Clock ◽

Suprachiasmatic Nucleus ◽

Daily Rhythms ◽

Specific Expression ◽

Central Clock ◽

And Behavior

Daily rhythms of physiology, metabolism, and behavior are orchestrated by a central circadian clock. In mice, this clock is coordinated by the suprachiasmatic nucleus, which consists of 20,000 neurons, making it challenging to characterize individual neurons. In Drosophila, the clock is controlled by only 150 clock neurons that distribute across the fly’s brain. Here, we describe a comprehensive set of genetic drivers to facilitate individual characterization of Drosophila clock neurons. We screened GAL4 lines that were obtained from Drosophila stock centers and identified 63 lines that exhibit expression in subsets of central clock neurons. Furthermore, we generated split-GAL4 lines that exhibit specific expression in subsets of clock neurons such as the 2 DN2 neurons and the 6 LPN neurons. Together with existing driver lines, these newly identified ones are versatile tools that will facilitate a better understanding of the Drosophila central circadian clock.

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Circadian clock gene Period2 regulates a time-of-day–dependent variation in cutaneous anaphylactic reaction

Journal of Allergy and Clinical Immunology ◽

10.1016/j.jaci.2011.02.006 ◽

2011 ◽

Vol 127 (4) ◽

pp. 1038-1045.e3 ◽

Cited By ~ 48

Author(s):

Yuki Nakamura ◽

Daisuke Harama ◽

Naomi Shimokawa ◽

Mutsuko Hara ◽

Ryuyo Suzuki ◽

...

Keyword(s):

Circadian Clock ◽

Anaphylactic Reaction ◽

Clock Gene ◽

Time Of Day ◽

Circadian Clock Gene

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Circadian clock protein Rev-erbα regulates neuroinflammation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1812405116 ◽

2019 ◽

Vol 116 (11) ◽

pp. 5102-5107 ◽

Cited By ~ 36

Author(s):

Percy Griffin ◽

Julie M. Dimitry ◽

Patrick W. Sheehan ◽

Brian V. Lananna ◽

Chun Guo ◽

...

Keyword(s):

Circadian Clock ◽

Microglial Activation ◽

Time Of Day ◽

Resting State Functional Connectivity ◽

Promoter Regions ◽

Clock Component ◽

Glial Cultures ◽

Inflammatory Phenotype

Circadian dysfunction is a common attribute of many neurodegenerative diseases, most of which are associated with neuroinflammation. Circadian rhythm dysfunction has been associated with inflammation in the periphery, but the role of the core clock in neuroinflammation remains poorly understood. Here we demonstrate that Rev-erbα, a nuclear receptor and circadian clock component, is a mediator of microglial activation and neuroinflammation. We observed time-of-day oscillation in microglial immunoreactivity in the hippocampus, which was disrupted in Rev-erbα−/− mice. Rev-erbα deletion caused spontaneous microglial activation in the hippocampus and increased expression of proinflammatory transcripts, as well as secondary astrogliosis. Transcriptomic analysis of hippocampus from Rev-erbα−/− mice revealed a predominant inflammatory phenotype and suggested dysregulated NF-κB signaling. Primary Rev-erbα−/− microglia exhibited proinflammatory phenotypes and increased basal NF-κB activation. Chromatin immunoprecipitation revealed that Rev-erbα physically interacts with the promoter regions of several NF-κB–related genes in primary microglia. Loss of Rev-erbα in primary astrocytes had no effect on basal activation but did potentiate the inflammatory response to lipopolysaccharide (LPS). In vivo, Rev-erbα−/− mice exhibited enhanced hippocampal neuroinflammatory responses to peripheral LPS injection, while pharmacologic activation of Rev-erbs with the small molecule agonist SR9009 suppressed LPS-induced hippocampal neuroinflammation. Rev-erbα deletion influenced neuronal health, as conditioned media from Rev-erbα–deficient primary glial cultures exacerbated oxidative damage in cultured neurons. Rev-erbα−/− mice also exhibited significantly altered cortical resting-state functional connectivity, similar to that observed in neurodegenerative models. Our results reveal Rev-erbα as a pharmacologically accessible link between the circadian clock and neuroinflammation.

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