19,044 results match your criteria circadian clock


The circadian clock component BMAL1 regulates SARS-CoV-2 entry and replication in lung epithelial cells.

iScience 2021 Sep 16:103144. Epub 2021 Sep 16.

Nuffield Department of Medicine, University of Oxford, Oxford, UK.

The COVID-19 pandemic, caused by SARS-CoV-2 coronavirus, is a global health issue with unprecedented challenges for public health. SARS-CoV-2 primarily infects cells of the respiratory tract via Spike glycoprotein binding to angiotensin-converting enzyme (ACE2). Circadian rhythms coordinate an organism's response to its environment and can regulate host susceptibility to virus infection. Read More

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September 2021

Spermidine resets circadian clock phase in NIH3T3 cells.

Biomed Res 2021 ;42(5):221-227

Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University.

Irregular light-dark cycles desynchronize the circadian clock via hormonal and neuronal pathways and increase the risk of various diseases. This study demonstrated that a single pulse of spermidine-a polyamine-strongly induced circadian phase advances in the presence or absence of dexamethasone (a synthetic glucocorticoid) in NIH3T3 cells transfected with the Bmal1 promotor-driven luciferase reporter gene. The spermidine-induced phase advances were 2-3 fold greater than were the dexamethasone-induced shifts. Read More

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January 2021

Regulatory Effects of Clock and Bmal1 on Circadian Rhythmic TLR Expression.

Int Rev Immunol 2021 Sep 20:1-12. Epub 2021 Sep 20.

Department of Pharmacology, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China.

Circadian locomotor output cycles kaput (Clock) and brain and muscle ARNT-like 1 (Bmal1) are two core circadian clock genes. They form a heterodimer that can bind to the E-box element in the promoters of Period circadian protein (Per) and Cryptochrome (Cry) genes, thereby inducing the rhythmic expression of circadian clock control genes. Toll-like receptors (TLRs) are type I transmembrane proteins belonging to the pattern recognition receptor (PRR) family. Read More

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September 2021

Is There a Link between Orcadian Clock Protein PERIOD 3 (PER3) (rs57875989) Variant and the Severity of COVID-19 Infection?

Curr Med Sci 2021 Sep 20. Epub 2021 Sep 20.

Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Istanbul, 34098, Turkey.

Objective: Corona Virus Disease-2019 (COVID-19) has been among the major infectious events of the century. In today's literature where COVID-19 and host factor effects are frequently examined, we aimed to examine another factor: Circadian Clock Protein PERIOD 3 (PER3). There is a significant correlation between PER3 gene polymorphism and circadian rhythm disturbances and immune system dysregulation. Read More

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September 2021

L-Theanine inhibits melanoma cell growth and migration via regulating expression of the clock gene BMAL1.

Eur J Nutr 2021 Sep 20. Epub 2021 Sep 20.

State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, 210023, Jiangsu, China.

Purpose: L-Theanine is a unique non-protein amino acid found in green tea, which has been identified as a safe dietary supplement. It has been reported that L-theanine exerts various biological activities. In this study, we explored the anti-cancer effects of L-theanine on melanoma cells. Read More

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September 2021

Binge Alcohol Disrupts Skeletal Muscle Core Molecular Clock Independent of Glucocorticoids.

Am J Physiol Endocrinol Metab 2021 Sep 20. Epub 2021 Sep 20.

Department of Nutrition and Integrative Physiology, grid.255986.5Florida State University, Tallahassee, FL, United States.

Circadian rhythms are central to optimal physiological function as disruption contributes to the development of several chronic diseases. Alcohol (EtOH) intoxication disrupts circadian rhythms within liver, brain, and intestines, but it is unknown whether alcohol also disrupts components of the core clock in skeletal muscle. Female C57BL/6Hsd mice were randomized to receive either saline (control) or alcohol (EtOH) (5g/kg) via intraperitoneal injection at the start of the dark cycle (ZT12), and gastrocnemius was collected every 4hr from Control and EtOH treated mice for the next 48hr following isoflurane anesthetization. Read More

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September 2021

Stereotaxic Surgery for Suprachiasmatic Nucleus Lesions in Mice.

Bio Protoc 2017 Jun 20;7(12):e2346. Epub 2017 Jun 20.

Department of Biological Sciences, School of Science, the University of Tokyo, Tokyo, 113-0033 Japan.

Site-specific lesions are invaluable methods for investigating the function of brain regions within the central nervous system and can be used to study neural mechanisms of behaviors. Precise stereotaxic surgery is required to lesion small regions of the brain such as the suprachiasmatic nucleus (SCN), which harbors the master circadian clock. In this protocol, we describe stereotaxic surgery optimized for bilateral lesion of the mouse SCN by loading electric current. Read More

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The Circadian Clock Is Sustained in the Thyroid Gland of VIP Receptor 2 Deficient Mice.

Front Endocrinol (Lausanne) 2021 1;12:737581. Epub 2021 Sep 1.

Department of Clinical Biochemistry, Bispebjerg and Frederiksberg Hospital, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.

VIP/VPAC2-receptor signaling is crucial for functioning of the circadian clock in the suprachiasmatic nucleus (SCN) since the lack results in disrupted synchrony between SCN cells and altered locomotor activity, body temperature, hormone secretion and heart rhythm. Endocrine glands, including the thyroid, show daily oscillations in clock gene expression and hormone secretion, and SCN projections target neurosecretory hypothalamic thyroid-stimulating hormone (TSH)-releasing hormone cells. The aim of the study was to gain knowledge of mechanisms important for regulation of the thyroid clock by evaluating the impact of VIP/VPAC2-receptor signaling. Read More

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September 2021

: A Regulator of Multiple Tissue-Specific Circadian Functions.

Front Mol Neurosci 2021 3;14:718387. Epub 2021 Sep 3.

Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany.

The zebrafish represents a powerful model for exploring how light regulates the circadian clock due to the direct light sensitivity of its peripheral clocks, a property that is retained even in organ cultures as well as zebrafish-derived cell lines. Light-inducible expression of the clock gene has been predicted to play a vital function in relaying light information to the core circadian clock mechanism in many organisms, including zebrafish. To directly test the contribution of to circadian clock function in zebrafish, we have generated a loss-of-function gene mutation. Read More

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September 2021

The circadian clock and diseases of the skin.

FEBS Lett 2021 Sep 17. Epub 2021 Sep 17.

Center for Complex Biological Systems, University of California, Irvine, CA, 92697, USA.

Organisms have an evolutionarily conserved internal rhythm that helps them anticipate and adapt to daily changes in the environment. Synchronized to the light-dark cycle with a period of around 24 hours, the timing of the circadian clock is set by light-triggering signals sent from the retina to the suprachiasmatic nucleus. Other inputs, including food intake, exercise, and temperature, also affect clocks in peripheral tissues, including skin. Read More

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September 2021

Time to eat reveals the hierarchy of peripheral clocks.

Trends Cell Biol 2021 Sep 14. Epub 2021 Sep 14.

Department of Cardiology and the Center for Circadian Metabolism and Cardiovascular Disease, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, China; Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, China. Electronic address:

Meal timing resets trillions of cellular circadian clocks in the body. Recent advances in multiomics demonstrate that clocks in peripheral tissues are differentially reset by feeding rhythm, and modulated by the central clock and the liver clock. This highlights the essential roles of tissue-specific regulation and intercellular signaling in clock synchronization. Read More

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September 2021

The circadian clock gene, Bmal1, regulates intestinal stem cell signaling and represses tumor initiation.

Cell Mol Gastroenterol Hepatol 2021 Sep 14. Epub 2021 Sep 14.

Department of Biomedical Sciences, University of Windsor, Windsor, N9B 3P4, Ontario. Electronic address:

Background: Circadian rhythms are daily physiological oscillations driven by the circadian clock: a 24-hour transcriptional timekeeper that regulates hormones, inflammation, and metabolism. Circadian rhythms are known to be important for health, but whether their loss contributes to colorectal cancer is not known.

Aims: We tested the non-redundant clock gene, Bmal1, in intestinal homeostasis and tumorigenesis, using the Apc model of colorectal cancer. Read More

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September 2021

Metabolic homeostasis: it's all in the timing.

Endocrinology 2021 Sep 17. Epub 2021 Sep 17.

Department of Physiology, University of Toronto, Toronto, Canada.

Cross-talk between peripheral tissues is essential to ensure the coordination of nutrient intake with disposition during the feeding period, thereby preventing metabolic disease. This Mini-review considers the interactions between the key peripheral tissues that constitute the metabolic clock, each of which is considered in a separate Mini-review in this collation of articles published in Endocrinology in 2020/2021, by: Martchenko et al. (Circadian Rhythms and the Gastrointestinal Tract: Relationship to Metabolism and Gut Hormones); Alvarez et al. Read More

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September 2021

Daily coordination of orexinergic gating in the rat superior colliculus-Implications for intrinsic clock activities in the visual system.

FASEB J 2021 Oct;35(10):e21930

Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland.

The orexinergic system delivers excitation for multiple brain centers to facilitate behavioral arousal, with its malfunction resulting in narcolepsy, somnolence, and notably, visual hallucinations. Since the circadian clock underlies the daily arousal, a timed coordination is expected between the orexin system and its target subcortical visual system, including the superior colliculus (SC). Here, we use a combination of electrophysiological, immunohistochemical, and molecular approaches across 24 h, together with the neuronal tract-tracing methods to investigate the daily coordination between the orexin system and the rodent SC. Read More

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October 2021

Structure-based design and classifications of small molecules regulating the circadian rhythm period.

Sci Rep 2021 Sep 16;11(1):18510. Epub 2021 Sep 16.

Department of Chemical and Biological Engineering, Koc University, Rumelifeneri Yolu, Sariyer, Istabul, Turkey.

Circadian rhythm is an important mechanism that controls behavior and biochemical events based on 24 h rhythmicity. Ample evidence indicates disturbance of this mechanism is associated with different diseases such as cancer, mood disorders, and familial delayed phase sleep disorder. Therefore, drug discovery studies have been initiated using high throughput screening. Read More

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September 2021

Marathon run performance on daylight savings time transition days: results from a natural experiment.

Chronobiol Int 2021 Sep 16:1-7. Epub 2021 Sep 16.

Department of Medicine, University of Central Florida, Orlando, Florida, USA.

Advancing clock times by 1 h in the spring to daylight savings time and setting clock times back 1 h in the autumn to standard time disrupts circadian timing, sleep and skilled motor behavior such as driving an automobile. It is unknown if endurance performance is impacted by daylight savings transition (DST). The natural experiment described here examined whether exposure to a DST in the 10 h prior to the start of a marathon race was associated with a different mean completion time compared to participants who ran the same course but were unexposed to a recent DST. Read More

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September 2021

Effects of Cryptochrome-modulating compounds on circadian behavioral rhythms in zebrafish.

J Biochem 2021 Sep 16. Epub 2021 Sep 16.

Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, Japan.

The circadian clock controls daily rhythms of various physiological processes, and impairment of its function causes many diseases including sleep disorders. Chemical compounds that regulate clock function are expected to be applied for treatment of circadian clock-related diseases. We previously identified small-molecule compounds KL001, KL101, and TH301 that lengthen the period of cellular circadian clock by directly targeting clock proteins Cryptochromes (CRYs) in mammals. Read More

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September 2021

Effect of regular and irregular stimulation cycles of dexamethasone on circadian clock in NIH3T3 cells.

Chronobiol Int 2021 Sep 15:1-9. Epub 2021 Sep 15.

Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.

Animal studies have shown that irregular light-dark cycles cause circadian desynchronization, while few studies have addressed the effect of regular/irregular stimulation cycles of signaling hormones on the cellular clock . Here, we examined how cellular clocks respond to regular and irregular stimulation cycles of dexamethasone, using NIH3T3 cells transfected with the promoter-driven luciferase () reporter gene. Cyclic stimulation with dexamethasone at different time intervals (18-28 h, 3 times regularly) revealed that bioluminescence rhythms can be entrained to 22 and 24 h cycles during the stimulation period, but not to other cycles. Read More

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September 2021

Disruption of the circadian rhythms and its relationship with pediatric obesity.

Authors:
Masanobu Kawai

Pediatr Int 2021 Sep 15. Epub 2021 Sep 15.

Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital.

The circadian clock system is an evolutionarily conserved system by which organisms adapt their metabolic activities to environmental inputs, including nutrient availability. The disruption of this system has been pathogenically linked to the disintegration of metabolic homeostasis, leading to the development of metabolic complications, including obesity. Lifestyle factors that disrupt this system have recently been emerging and associated with the development of obesity, which is most evidenced by the finding that shift workers are at an increased risk of developing various disorders, such as obesity and obesity-related complications. Read More

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September 2021

Corrigendum to "Circadian clock gene NPAS2 promotes reprogramming of glucose metabolism in hepatocellular carcinoma cells" [Canc. Lett. 469 (2020) 498-509].

Cancer Lett 2021 Sep 11. Epub 2021 Sep 11.

State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, China. Electronic address:

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September 2021

Circadian regulation of cardiac muscle function and protein degradation.

Authors:
Seung-Hee Yoo

Chronobiol Int 2021 Sep 14:1-9. Epub 2021 Sep 14.

Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, Texas, USA.

The circadian clock plays a fundamental role in physiology. In particular, the heart is a target organ where the clock orchestrates various aspects of cardiac function. At the molecular level, the clock machinery governs daily rhythms of gene expression. Read More

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September 2021

L-cell Arntl is required for rhythmic glucagon-like peptide-1 secretion and maintenance of intestinal homeostasis.

Mol Metab 2021 Sep 11:101340. Epub 2021 Sep 11.

Department of Physiology, University of Toronto; Department of Medicine, University of Toronto, Toronto, ON, Canada. Electronic address:

Objectives: Recent studies using whole-body clock-disrupted animals identified a disruption in the circadian rhythm of the intestinal L-cell incretin hormone, glucagon-like peptide-1 (GLP-1). Although GLP-1 plays an essential role in metabolism, through enhancement of both glucose-stimulated insulin secretion and satiety, recent evidenced has also demonstrated its importance in regulating intestinal and microbial homeostasis. Therefore, using in vivo and in vitro models, this study assessed the requirement for the core circadian clock gene Arntl in the regulation of GLP-1 secretion and its impact on the intestinal environment. Read More

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September 2021

Modelling the functional roles of synaptic and extra-synaptic γ-aminobutyric acid receptor dynamics in circadian timekeeping.

J R Soc Interface 2021 Sep 15;18(182):20210454. Epub 2021 Sep 15.

Department of Chemical Engineering and the Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, USA.

In the suprachiasmatic nucleus (SCN), γ-aminobutyric acid (GABA) is a primary neurotransmitter. GABA can signal through two types of GABA receptor subunits, often referred to as synaptic GABA (gamma subunit) and extra-synaptic GABA (delta subunit). To test the functional roles of these distinct GABA in regulating circadian rhythms, we developed a multicellular SCN model where we could separately compare the effects of manipulating GABA neurotransmitter or receptor dynamics. Read More

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September 2021

Overfeeding during development induces temporally-dependent changes in areas controlling food intake in the brains of male Wistar rats.

Life Sci 2021 Sep 11;285:119951. Epub 2021 Sep 11.

Neuropsychiatry and Behavior Science Graduate Program, Universidade Federal de Pernambuco -UFPE-Recife, PE, Brazil; Laboratory of Biochemistry and Exercise Biochemistry, Universidade Federal de Pernambuco - UFPE, Recife, PE, Brazil. Electronic address:

Aims: We sought to evaluate the effects of overfeeding during lactation on the feeding behavior and expression of specific regulatory genes in brain areas associated with food intake in 22- and 60-day old male rats.

Methods: We evaluated body weight, food intake of standard and palatable diet, and mRNA expression of dopamine receptor D1 (DDR1), dopamine receptor (DDR2), melanocortin 4 receptor (MC4R), the μ-opioid receptor (MOR), neuropeptide Y (NPY), agouti-related protein (AGRP), proopiomelanocortin (POMC), cocaine-and amphetamine-regulated transcript (CART), serotonin (5-hydroxytryptamine; 5-HT) transporter (SERT), 5-hydroxytryptamine receptor 1B (5-HT1B), 5-hydroxytryptamine receptor 2C receptor (5-HT2C), Clock (CLOK), cryptochrome protein 1 (Cry1) and period circadian protein homolog 2 (Per2) in the striatum, hypothalamus and brainstem of male rats at post-natal days (PND) 22 and 60.

Key Findings: Overfeeding resulted in significantly increased body weight through PND60, and a 2-fold increase in palatable food intake at PND22, but not at PND60. Read More

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September 2021

Downregulation of Arntl mRNA Expression in Women with Hypertension: A Case-Control Study.

Kidney Blood Press Res 2021 Sep 3:1-8. Epub 2021 Sep 3.

Department of Epidemiology, School of Public Health, and Institute of Chronic Disease Prevention and Control, Wannan Medical College, Wuhu, China.

Background: Previous studies have reported that disturbance of endogenous circadian rhythms enhances the chance of hypertension and suggested that circadian clock genes could have a crucial function in the onset of the disease. This case-control study was aimed to investigate the association of the mRNA expression of aryl hydrocarbon receptor nuclear translocator like (Arntl), clock circadian regulator (Clock), and period circadian regulators 1 and 2 (Per1 and Per2) with hypertension and blood pressure levels.

Methods: A total of 172 subjects were recruited in this study, including 86 hypertension and 86 nonhypertension controls. Read More

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September 2021

Casein Kinase 1 Epsilon and circadian misalignment impact affective behaviors in mice.

Eur J Neurosci 2021 Sep 12. Epub 2021 Sep 12.

Center for Sleep and Circadian Biology, Department of Neurobiology, Northwestern University, Evanston, IL, USA.

Affective behaviors and mental health are profoundly affected by disturbances in circadian rhythms. Casein kinase 1 epsilon (CSNK1E) is a core component of the circadian clock. Mice with tau or null mutation of this gene have shortened and lengthened circadian period respectively. Read More

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September 2021

Every Night and Every Morn: Effect of Variation in Gene on Depression Depends on Exposure to Early and Recent Stress.

Front Psychiatry 2021 26;12:687487. Epub 2021 Aug 26.

NAP-2-SE New Antidepressant Target Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary.

The role of circadian dysregulation is increasingly acknowledged in the background of depressive symptoms, and is also a promising treatment target. Similarly, stress shows a complex relationship with the circadian system. The gene, encoding a key element in circadian regulation has been implicated in previous candidate variant studies in depression with contradictory findings, and only a few such studies considered the interacting effects of stress. Read More

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The 50th anniversary of the Konopka and Benzer 1971 paper in PNAS: "Clock Mutants of ".

Proc Natl Acad Sci U S A 2021 Sep;118(39)

Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390;

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September 2021

Circadian rhythms in ischaemic heart disease. Key aspects for preclinical and translational research: Position paper of the ESC Working Group on Cellular Biology of the Heart.

Cardiovasc Res 2021 Sep 10. Epub 2021 Sep 10.

Cardiology and UMC Utrecht Regenerative Medicine Center, University Medical Center Utrecht, the Netherlands.

Circadian rhythms are internal regulatory processes controlled by molecular clocks present in essentially every mammalian organ that temporally regulate major physiological functions. In the cardiovascular system, the circadian clock governs heart rate, blood pressure, cardiac metabolism, contractility and coagulation. Recent experimental and clinical studies highlight the possible importance of circadian rhythms in the pathophysiology, outcome, or treatment success of cardiovascular disease, including ischaemic heart disease. Read More

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September 2021

Dorsal clock neurons in sculpt locomotor outputs but are dispensable for circadian activity rhythms.

iScience 2021 Sep 19;24(9):103001. Epub 2021 Aug 19.

Department of Biology, Loyola University Chicago, Chicago IL 60660, USA.

The circadian system is comprised three components: a network of core clock cells in the brain that keeps time, input pathways that entrain clock cells to the environment, and output pathways that use this information to ensure appropriate timing of physiological and behavioral processes throughout the day. Core clock cells can be divided into molecularly distinct populations that likely make unique functional contributions. Here we clarify the role of the dorsal neuron 1 (DN1) population of clock neurons in the transmission of circadian information by the core clock network. Read More

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September 2021