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Kim E, Yoo SH, Chen Z. Circadian stabilization loop: the regulatory hub and therapeutic target promoting circadian resilience and physiological health. F1000Res 2022; 11:1236. [PMID: 36415204 PMCID: PMC9652504 DOI: 10.12688/f1000research.126364.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/17/2022] [Indexed: 11/13/2022] Open
Abstract
The circadian clock is a fundamental biological mechanism that orchestrates essential cellular and physiological processes to optimize fitness and health. The basic functional unit is the cell-autonomous oscillator, consisting of intersecting negative feedback loops. Whereas the core loop is primarily responsible for rhythm generation, auxiliary loops, most notably the secondary or stabilization loop, play pivotal roles to confer temporal precision and molecular robustness. The stabilization loop contains opposing nuclear receptor subfamilies REV-ERBs and retinoic acid receptor-related orphan receptors (RORs), competing to modulate rhythmic expression of the basic helix-loop-helix ARNT like 1 ( Bmal1) genes in the core loop as well as other clock-controlled genes. Therefore, REV-ERBs and RORs are strategically located to interface the oscillator and the global transcriptomic network, promoting cellular homeostasis and physiological fitness throughout lifespan. Disruption of REV-ERB and ROR functions has been linked with diseases and aging, and pharmacological manipulation of these factors has shown promise in various mouse disease models. Nobiletin is a natural compound that directly binds to and activates RORα/γ, modulating circadian rhythms, and shows robust in vivo efficacies to combat clock-associated pathophysiologies and age-related decline. Results from several studies demonstrate an inverse relation between nobiletin efficacy and clock functional state, where nobiletin elicits little effect in young and healthy mice with growing efficacy as the clock is perturbed by environmental and genetic challenges. This mode of action is consistent with the function of the stabilization loop to promote circadian and physiological resilience. Future studies should further investigate the function and mechanism of REV-ERBs and RORs, and test strategies targeting these factors against disease and aging.
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Affiliation(s)
- Eunju Kim
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, 77030, USA
| | - Seung-Hee Yoo
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, 77030, USA
| | - Zheng Chen
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, 77030, USA,
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Kim E, Yoo SH, Chen Z. Circadian stabilization loop: the regulatory hub and therapeutic target promoting circadian resilience and physiological health. F1000Res 2022; 11:1236. [PMID: 36415204 PMCID: PMC9652504.2 DOI: 10.12688/f1000research.126364.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/06/2022] [Indexed: 12/14/2022] Open
Abstract
The circadian clock is a fundamental biological mechanism that orchestrates essential cellular and physiological processes to optimize fitness and health. The basic functional unit is the cell-autonomous oscillator, consisting of intersecting negative feedback loops. Whereas the core loop is primarily responsible for rhythm generation, auxiliary loops, most notably the secondary or stabilization loop, play pivotal roles to confer temporal precision and molecular robustness. The stabilization loop contains opposing nuclear receptor subfamilies REV-ERBs and retinoic acid receptor-related orphan receptors (RORs), competing to modulate rhythmic expression of the basic helix-loop-helix ARNT like 1 ( Bmal1) genes in the core loop as well as other clock-controlled genes. Therefore, REV-ERBs and RORs are strategically located to interface the oscillator and the global transcriptomic network, promoting cellular homeostasis and physiological fitness throughout lifespan. Disruption of REV-ERB and ROR functions has been linked with diseases and aging, and pharmacological manipulation of these factors has shown promise in various mouse disease models. Nobiletin is a natural compound that directly binds to and activates RORα/γ, modulating circadian rhythms, and shows robust in vivo efficacies to combat clock-associated pathophysiologies and age-related decline. Results from several studies demonstrate an inverse relation between nobiletin efficacy and clock functional state, where nobiletin elicits little effect in young and healthy mice with growing efficacy as the clock is perturbed by environmental and genetic challenges. This mode of action is consistent with the function of the stabilization loop to promote circadian and physiological resilience. Future studies should further investigate the function and mechanism of REV-ERBs and RORs, and test strategies targeting these factors against disease and aging.
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Affiliation(s)
- Eunju Kim
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, 77030, USA
| | - Seung-Hee Yoo
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, 77030, USA
| | - Zheng Chen
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, 77030, USA,
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Pourcet B, Duez H. Circadian Control of Inflammasome Pathways: Implications for Circadian Medicine. Front Immunol 2020; 11:1630. [PMID: 32849554 PMCID: PMC7410924 DOI: 10.3389/fimmu.2020.01630] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 06/18/2020] [Indexed: 12/25/2022] Open
Abstract
The innate immune system senses “non-self” molecules derived from pathogens (PAMPs) as well as endogenous damage-associated molecular patterns (DAMPs) and promotes sterile inflammation that is necessary for injury resolution, tissue repair/regeneration, and homeostasis. The NOD-, LRR- and pyrin domain containing protein 3 (NLRP3) is an innate immune signaling complex whose assembly and activation can be triggered by various signals ranging from microbial molecules to ATP or the abnormal accumulation of crystals, thus leading to IL-1β and IL-18 maturation and secretion. Deregulation of the NLRP3 signaling cascade is associated with numerous inflammatory and metabolic diseases including rheumatoid arthritis, gout, atherosclerosis or type 2 diabetes. Interestingly, the circadian clock controls numerous inflammatory processes while clock disruption leads to or exacerbates inflammation. Recently, the biological clock was demonstrated to control NLRP3 expression and activation, thereby controlling IL-1β and IL-18 secretion in diverse tissues and immune cells, particularly macrophages. Circadian oscillations of NLRP3 signaling is lost in models of clock disruption, contributing to the development of peritonitis, hepatitis, or colitis. Sterile inflammation is also an important driver of atherosclerosis, and targeting the production of IL-1β has proven to be a promising approach for atherosclerosis management in humans. Interestingly, the extent of injury after fulminant hepatitis or myocardial infarction is time-of-day dependent under the control of the clock, and chronotherapy represents a promising approach for the management of pathologies involving deregulation of NLRP3 signaling.
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Affiliation(s)
- Benoit Pourcet
- University of Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1011-EGID, Lille, France
| | - Hélène Duez
- University of Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1011-EGID, Lille, France
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Lee SM, Zhang Y, Tsuchiya H, Smalling R, Jetten AM, Wang L. Small heterodimer partner/neuronal PAS domain protein 2 axis regulates the oscillation of liver lipid metabolism. Hepatology 2015; 61:497-505. [PMID: 25212631 PMCID: PMC4303514 DOI: 10.1002/hep.27437] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 09/10/2014] [Indexed: 12/16/2022]
Abstract
UNLABELLED In mammals, circadian rhythms are essential for coordinating the timing of various metabolic processes. The Clock gene regulates diurnal plasma triglyceride fluctuation through nuclear receptor small heterodimer partner (Shp; Nr0b2). Given that SHP is a critical regulator of metabolism in the liver, it is unknown whether SHP is necessary to coordinate metabolism and circadian rhythms. Shp(+/+) and Shp(-/-) mice on a C57BL/6 background (n = 3-5/group) were fed a standard chow diet and water ad libitum. Serum and livers were collected at zeitgeber time 2, 6, 10, 14, 18, and 22. In vivo and in vitro assays included RNA sequencing, quantitative polymerase chain reaction, very-low-density lipoprotein production, adenovirus overexpression and small interfering RNA knockdown, serum parameters, circadian locomotor activity, Oil Red O staining, transient transfection, luciferase reporter assay, chromatin immunoprecipitation assay, gel-shift assay, coimmunoprecipitation, and western blottings. Shp deficiency had a robust global impact on major liver metabolic genes. Several components of the liver clock, including peroxisome proliferator-activated receptor-γ, coactivator 1 (Pgc-1α), neuronal PAS domain-containing protein 2 (Npas2), and retinoic acid-related orphan receptor (Ror)α/γ were sharply induced in Shp(-/-) liver. At the molecular level, SHP inhibited Npas2 gene transcription and promoter activity through interaction with Rorγ to repress Rorγ transactivation and by interacting with Rev-erbα to enhance its inhibition of Rorα activity. Conversely, Npas2 controlled the circadian rhythm of Shp expression by binding rhythmically to the Shp promoter, which was enhanced by nicotinamide adenine dinucleotide, but not nicotinamide adenine dinucleotide phosphate. Phenotypically, Npas2 deficiency induced severe steatosis in Shp(-/-) mice, which was attributed to the dysregulation of lipoprotein metabolism. CONCLUSION Shp and Npas2 crosstalk is essential to maintain hepatic lipid homeostasis.
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Affiliation(s)
- Sang Min Lee
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269
| | - Yuxia Zhang
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Hiroyuki Tsuchiya
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Rana Smalling
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Anton M. Jetten
- Cell Biology Section, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health Research Triangle Park, NC 27709
| | - Li Wang
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269,Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, CT 06520,Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516,Correspondence: Tel: 801-739-4646;
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Abstract
SIGNIFICANCE Skin, a complex organ and the body's first line of defense against environmental insults, plays a critical role in maintaining homeostasis in an organism. This balance is maintained through a complex network of cellular machinery and signaling events, including those regulating oxidative stress and circadian rhythms. These regulatory mechanisms have developed integral systems to protect skin cells and to signal to the rest of the body in the event of internal and environmental stresses. RECENT ADVANCES Interestingly, several signaling pathways and many bioactive molecules have been found to be involved and even important in the regulation of oxidative stress and circadian rhythms, especially in the skin. It is becoming increasingly evident that these two regulatory systems may, in fact, be interconnected in the regulation of homeostasis. Important examples of molecules that connect the two systems include serotonin, melatonin, vitamin D, and vitamin A. CRITICAL ISSUES Excessive reactive oxygen species and/or dysregulation of antioxidant system and circadian rhythms can cause critical errors in maintaining proper barrier function and skin health, as well as overall homeostasis. Unfortunately, the modern lifestyle seems to contribute to increasing alterations in redox balance and circadian rhythms, thereby posing a critical problem for normal functioning of the living system. FUTURE DIRECTIONS Since the oxidative stress and circadian rhythm systems seem to have areas of overlap, future research needs to be focused on defining the interactions between these two important systems. This may be especially important in the skin where both systems play critical roles in protecting the whole body.
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Affiliation(s)
- Mary A Ndiaye
- 1 Department of Dermatology, University of Wisconsin , Madison, Wisconsin
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Stöhr R, Marx N, Federici M. Tick-tock: is your cardiometabolic risk on the clock? Diab Vasc Dis Res 2014; 11:66-74. [PMID: 24396116 DOI: 10.1177/1479164113516348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Governing a large amount of cellular processes in mammalian cells is a 24-h regulatory mechanism known as the circadian clock. Through the release of neurohormonal factors, the master central clock is able to regulate the otherwise independent peripheral clocks situated in all vital organs. It has recently been shown that forced misalignment of the circadian cycles, often as a consequence of lifestyle factors, is an independent cardiometabolic risk factor and may thus potentially predispose certain groups, such as nightshift workers, to cardiovascular disease. In this review, we will analyse some of the recent advances regarding circadian clock dysfunction and the development of cardiovascular diseases. Finally, we will touch on the developing link between circadian dysfunction and myocardial infarctions.
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Affiliation(s)
- Robert Stöhr
- Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy
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Anea CB, Zhang M, Chen F, Ali MI, Hart CMM, Stepp DW, Kovalenkov YO, Merloiu AM, Pati P, Fulton D, Rudic RD. Circadian clock control of Nox4 and reactive oxygen species in the vasculature. PLoS One 2013; 8:e78626. [PMID: 24205282 PMCID: PMC3808297 DOI: 10.1371/journal.pone.0078626] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 09/14/2013] [Indexed: 12/30/2022] Open
Abstract
Recent studies have shown that circadian clock disruption is associated with pathological remodeling in the arterial structure and vascular stiffness. Moreover, chronic circadian disruption is associated with dysfunction in endothelial responses and signaling. Reactive oxygen species have emerged as key regulators in vascular pathology. Previously, we have demonstrated that circadian clock dysfunction exacerbates superoxide production through eNOS uncoupling. To date, the impact of circadian clock mutation on vascular NADPH oxidase expression and function is not known. The goal in the current study was to determine if the circadian clock controls vascular Nox4 expression and hydrogen peroxide formation in arteries, particularly in endothelial and vascular smooth muscle cells. In aorta, there was an increase in hydrogen peroxide and Nox4 expression in mice with a dysfunctional circadian rhythm (Bmal1-KO mice). In addition, the Nox4 gene promoter is activated by the core circadian transcription factors. Lastly, in synchronized cultured human endothelial cells, Nox4 gene expression exhibited rhythmic oscillations. These data reveal that the circadian clock plays an important role in the control of Nox4 and disruption of the clock leads to subsequent production of reaction oxygen species.
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Affiliation(s)
- Ciprian B. Anea
- Department of Pharmacology & Toxicology, Georgia Regents University, Augusta, Georgia, United States of America
| | - Maoxiang Zhang
- Department of Pharmacology & Toxicology, Georgia Regents University, Augusta, Georgia, United States of America
| | - Feng Chen
- Vascular Biology Center, Georgia Regents University, Augusta, Georgia, United States of America
| | - M. Irfan Ali
- Vascular Biology Center, Georgia Regents University, Augusta, Georgia, United States of America
| | - C. Michael M. Hart
- Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Center, Atlanta, Georgia, United States of America
| | - David W. Stepp
- Vascular Biology Center, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Physiology, Georgia Regents University, Augusta, Georgia, United States of America
| | - Yevgeniy O. Kovalenkov
- Vascular Biology Center, Georgia Regents University, Augusta, Georgia, United States of America
| | - Ana-Maria Merloiu
- Department of Pharmacology & Toxicology, Georgia Regents University, Augusta, Georgia, United States of America
| | - Paramita Pati
- Department of Pharmacology & Toxicology, Georgia Regents University, Augusta, Georgia, United States of America
| | - David Fulton
- Vascular Biology Center, Georgia Regents University, Augusta, Georgia, United States of America
| | - R. Daniel Rudic
- Department of Pharmacology & Toxicology, Georgia Regents University, Augusta, Georgia, United States of America
- * E-mail:
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8
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Buijs R, Salgado R, Sabath E, Escobar C. Peripheral Circadian Oscillators. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 119:83-103. [DOI: 10.1016/b978-0-12-396971-2.00004-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Miyazaki M, Schroder E, Edelmann SE, Hughes ME, Kornacker K, Balke CW, Esser KA. Age-associated disruption of molecular clock expression in skeletal muscle of the spontaneously hypertensive rat. PLoS One 2011; 6:e27168. [PMID: 22076133 PMCID: PMC3208587 DOI: 10.1371/journal.pone.0027168] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 10/11/2011] [Indexed: 12/17/2022] Open
Abstract
It is well known that spontaneously hypertensive rats (SHR) develop muscle pathologies with hypertension and heart failure, though the mechanism remains poorly understood. Woon et al. (2007) linked the circadian clock gene Bmal1 to hypertension and metabolic dysfunction in the SHR. Building on these findings, we compared the expression pattern of several core-clock genes in the gastrocnemius muscle of aged SHR (80 weeks; overt heart failure) compared to aged-matched control WKY strain. Heart failure was associated with marked effects on the expression of Bmal1, Clock and Rora in addition to several non-circadian genes important in regulating skeletal muscle phenotype including Mck, Ttn and Mef2c. We next performed circadian time-course collections at a young age (8 weeks; pre-hypertensive) and adult age (22 weeks; hypertensive) to determine if clock gene expression was disrupted in gastrocnemius, heart and liver tissues prior to or after the rats became hypertensive. We found that hypertensive/hypertrophic SHR showed a dampening of peak Bmal1 and Rev-erb expression in the liver, and the clock-controlled gene Pgc1α in the gastrocnemius. In addition, the core-clock gene Clock and the muscle-specific, clock-controlled gene Myod1, no longer maintained a circadian pattern of expression in gastrocnemius from the hypertensive SHR. These findings provide a framework to suggest a mechanism whereby chronic heart failure leads to skeletal muscle pathologies; prolonged dysregulation of the molecular clock in skeletal muscle results in altered Clock, Pgc1α and Myod1 expression which in turn leads to the mis-regulation of target genes important for mechanical and metabolic function of skeletal muscle.
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MESH Headings
- Age Factors
- Animals
- Blotting, Western
- CLOCK Proteins/genetics
- CLOCK Proteins/metabolism
- Circadian Clocks/physiology
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Gene Expression Regulation, Developmental
- Heart/physiopathology
- Hypertension/physiopathology
- Liver/metabolism
- Liver/pathology
- Male
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- MyoD Protein/genetics
- MyoD Protein/metabolism
- Nuclear Receptor Subfamily 1, Group D, Member 1/genetics
- Nuclear Receptor Subfamily 1, Group D, Member 1/metabolism
- Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
- RNA, Messenger/genetics
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Rats
- Rats, Inbred SHR
- Rats, Inbred WKY
- Real-Time Polymerase Chain Reaction
- Transcription Factors/genetics
- Transcription Factors/metabolism
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Affiliation(s)
- Mitsunori Miyazaki
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Elizabeth Schroder
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
| | - Stephanie E. Edelmann
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Michael E. Hughes
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, United States of America
| | - Karl Kornacker
- Division of Sensory Biophysics, Ohio State University, Columbus, Ohio, United States of America
| | - C. William Balke
- Clinical and Translational Science Institute and the Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Karyn A. Esser
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, United States of America
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Jolma IW, Laerum OD, Lillo C, Ruoff P. Circadian oscillators in eukaryotes. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 2:533-549. [PMID: 20836046 DOI: 10.1002/wsbm.81] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The biological clock, present in nearly all eukaryotes, has evolved such that organisms can adapt to our planet's rotation in order to anticipate the coming day or night as well as unfavorable seasons. As all modern high-precision chronometers, the biological clock uses oscillation as a timekeeping element. In this review, we describe briefly the discovery, historical development, and general properties of circadian oscillators. The issue of temperature compensation (TC) is discussed, and our present understanding of the underlying genetic and biochemical mechanisms in circadian oscillators are described with special emphasis on Neurospora crassa, mammals, and plants.
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Affiliation(s)
- Ingunn W Jolma
- Centre of Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Ole Didrik Laerum
- The Gade Institute, Department of Pathology, Haukeland University Hospital, N-5021 Bergen, Norway
| | - Cathrine Lillo
- Centre of Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Peter Ruoff
- Centre of Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
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11
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Schroeder A, Loh DH, Jordan MC, Roos KP, Colwell CS. Circadian regulation of cardiovascular function: a role for vasoactive intestinal peptide. Am J Physiol Heart Circ Physiol 2010; 300:H241-50. [PMID: 20952671 DOI: 10.1152/ajpheart.00190.2010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The circadian system, driven by the suprachiasmatic nucleus (SCN), regulates properties of cardiovascular function. The dysfunction of this timing system can result in cardiac pathology. The neuropeptide vasoactive intestinal peptide (VIP) is crucial for circadian rhythms in a number of biological processes including SCN electrical activity and wheel running behavior. Anatomic evidence indicates that SCN neurons expressing VIP are well positioned to drive circadian regulation of cardiac function through interactions with the autonomic centers. In this study, we tested the hypothesis that loss of VIP would result in circadian deficits in heart rate (HR) and clock gene expression in cardiac tissue. We implanted radiotelemetry devices into VIP-deficient mice and wild-type (WT) controls and continuously recorded HR, body temperature, and cage activity in freely moving mice. Under light-dark conditions, VIP-deficient mice displayed weak rhythms in HR, body temperature, and cage activity, with onsets that were advanced in phase compared with WT mice. Similarly, clock gene expression in cardiac tissue was rhythmic but phase advanced in mutant mice. In constant darkness, the normal circadian rhythms in HR were lost in VIP-deficient mice; however, most mutant mice continued to exhibit circadian rhythms of body temperature with shortened free-running period. The loss of VIP altered, but did not abolish, autonomic regulation of HR. Analysis of the echocardiograms did not find any evidence for a loss of cardiac function in VIP-deficient mice, and the size of the hearts did not differ between genotypes. These results demonstrate that VIP is an important regulator of physiological circadian rhythmicity in the heart.
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Affiliation(s)
- Analyne Schroeder
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, California 90024, USA
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12
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Crumbley C, Wang Y, Kojetin DJ, Burris TP. Characterization of the core mammalian clock component, NPAS2, as a REV-ERBalpha/RORalpha target gene. J Biol Chem 2010; 285:35386-92. [PMID: 20817722 DOI: 10.1074/jbc.m110.129288] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The mammalian clock is regulated at the cellular level by a transcriptional/translational feedback loop. BMAL1/clock (or NPAS2) heterodimers activate the expression of the period (PER) and cryptochrome (CRY) genes acting as transcription factors directed to the PER and CRY promoters via E-box elements. PER and CRY proteins form heterodimers and suppress the activity of the BMAL1/clock (or NPAS2) completing the feedback loop. The circadian expression of BMAL1 is influenced by retinoic acid receptor-related orphan receptor α (RORα) and REV-ERBα, two nuclear receptors that target a ROR-response element in the promoter of the BMAL1 gene. Given that BMAL1 functions as an obligate heterodimer with either clock or NPAS2, it is unclear how the expression of the partner is coordinated with BMAL1 expression. Here, we demonstrate that NPAS2 is also a RORα and REV-ERBα target gene. Using a ChIP/microarray screen, we identified both RORα and REV-ERBα occupancy of the NPAS2 promoter. We identified two functional ROREs within the NPAS2 promoter and also demonstrate that both RORα and REV-ERBα regulate the expression of NPAS2 mRNA. These data suggest a mechanism by which RORα and REV-ERBα coordinately regulate the expression of the positive arm of the circadian rhythm feedback loop.
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13
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Abstract
The circadian clock regulates many aspects of physiology, including cardiovascular function. Internal oscillators exist in endothelial, smooth muscle cells, and fibroblasts of the vasculature. Vascular tone and thrombus formation, 2 key elements of vascular function with regard to adverse cardiovascular events, exhibit diurnal rhythmicity. In this review, we describe changes in vascular function that result from genetic disruption of discrete elements of the circadian clock.
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Affiliation(s)
- Georgios K Paschos
- Department of Pharmacology, 153 Johnson Pavilion, 3620 Hamilton Walk, Philadelphia, PA 19104-6084.
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14
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Abstract
Hypertension is a major risk factor for cardiovascular disease and death. The "silent" rise of blood pressure that occurs over time is largely asymptomatic. However, its impact is deafening-causing and exacerbating cardiovascular disease, end-organ damage, and death. The present article addresses recent observations from human and animal studies that provide new insights into how the circadian clock regulates blood pressure, contributes to hypertension, and ultimately evolves vascular disease. Further, the molecular components of the circadian clock and their relationship with locomotor activity, metabolic control, fluid balance, and vascular resistance are discussed with an emphasis on how these novel, circadian clock-controlled mechanisms contribute to hypertension.
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Affiliation(s)
- R Daniel Rudic
- Department of Pharmacology and Toxicology, 1120 15th St., Medical College of Georgia, Augusta, GA 30912, USA.
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15
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Abstract
The westernised world is in the midst of an epidemic of type 2 diabetes and associated cardiovascular disease. These closely interlinked conditions have a common pathophysiological basis underpinned by insulin resistance and the metabolic syndrome. Contemporary changes in environmental factors on a background of genetic susceptibility are thought to account for the increases seen. Life on earth is governed by the 24-hour environment of light and darkness cycling with the rotation of the earth. Numerous metabolic and physiological pathways are coordinated to this 24-hour cycle by an endogenous clock. Recent epidemiological evidence and animal data suggest that disturbance of circadian rhythms through genetic and environmental influences on the molecular clock is pivotal in the pathogenesis of obesity, type 2 diabetes and cardiovascular disease. This review describes current knowledge on the topic.
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Affiliation(s)
- Madhu J Prasai
- Division of Cardiovascular and Diabetes Research, The Leeds Institute of Genetics Health and Therapeutics, Clarendon Way, University of Leeds, Leeds, LS2 9JT, UK
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16
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Abstract
Circadian rhythms are normal variations in physiological processes that occur over the period of a day. These rhythms are essential for the organism since they allow anticipatory metabolic regulations to prepare for the up-coming feeding or rest period. Disturbances of the biological clock predispose to metabolic disorders such as dyslipidaemia, insulin resistance and obesity. Moreover, certain pathological events, such as cardiovascular accidents (myocardial infarction, stroke) occur more frequently at specific times of the day. The nuclear receptors Rev-erbalpha and RORalpha are clock components involved in the regulation of the core clock circuitry. They are also important regulators of lipid and lipoprotein metabolism, adipogenesis and vascular inflammation. Moreover, they cross-talk with several other nuclear receptors controlling energy homeostasis. Therefore, Rev-erbalpha and RORalpha may play a central role in the coordination of metabolic processes and circadian outputs.
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Affiliation(s)
- Hélène Duez
- Institut Pasteur de Lille, 1, rue Calmette, BP 245, F-59019 Lille, France
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Peirson SN, Butler JN, Duffield GE, Takher S, Sharma P, Foster RG. Comparison of clock gene expression in SCN, retina, heart, and liver of mice. Biochem Biophys Res Commun 2006; 351:800-7. [PMID: 17092486 DOI: 10.1016/j.bbrc.2006.10.118] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Accepted: 10/10/2006] [Indexed: 11/18/2022]
Abstract
In mammals, the suprachiasmatic nuclei (SCN) in the hypothalamus are the site of a central circadian pacemaker, regulating overt rhythms of behaviour and coordinating the rhythmic activity of oscillators in peripheral tissues. Circadian rhythms in all tissues appear to arise from interacting transcriptional-translational feedback loops, involving a core set of clock genes. Whilst it seems likely that there will be broadly similar mechanisms between the central and peripheral oscillators, the extent to which the fine details of gene expression are conserved between different organs has yet to be assessed. In this study, we examine the molecular profile of clock genes within the central SCN pacemaker and peripheral oscillators, identifying differences in phasing, amplitude, waveform, and basal expression levels.
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Affiliation(s)
- Stuart N Peirson
- Circadian and Visual Neuroscience Group, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
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