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Salminen A. Aryl hydrocarbon receptor impairs circadian regulation in Alzheimer's disease: Potential impact on glymphatic system dysfunction. Eur J Neurosci 2024. [PMID: 38924210 DOI: 10.1111/ejn.16450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 05/23/2024] [Accepted: 06/10/2024] [Indexed: 06/28/2024]
Abstract
Circadian clocks maintain diurnal rhythms of sleep-wake cycle of 24 h that regulate not only the metabolism of an organism but also many other periodical processes. There is substantial evidence that circadian regulation is impaired in Alzheimer's disease. Circadian clocks regulate many properties known to be disturbed in Alzheimer's patients, such as the integrity of the blood-brain barrier (BBB) as well as the diurnal glymphatic flow that controls waste clearance from the brain. Interestingly, an evolutionarily conserved transcription factor, that is, aryl hydrocarbon receptor (AhR), impairs the function of the core clock proteins and thus could disturb diurnal rhythmicity in the BBB. There is abundant evidence that the activation of AhR signalling inhibits the expression of the major core clock proteins, such as the brain and muscle arnt-like 1 (BMAL1), clock circadian regulator (CLOCK) and period circadian regulator 1 (PER1) in different experimental models. The expression of AhR is robustly increased in the brains of Alzheimer's patients, and protein level is enriched in astrocytes of the BBB. It seems that AhR signalling inhibits glymphatic flow since it is known that (i) activation of AhR impairs the function of the BBB, which is cooperatively interconnected with the glymphatic system in the brain, and (ii) neuroinflammation and dysbiosis of gut microbiota generate potent activators of AhR, which are able to impair glymphatic flow. I will examine current evidence indicating that activation of AhR signalling could disturb circadian functions of the BBB and impair glymphatic flow and thus be involved in the development of Alzheimer's pathology.
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Affiliation(s)
- Antero Salminen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
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2
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Sanford ABA, da Cunha LS, Machado CB, de Pinho Pessoa FMC, Silva ANDS, Ribeiro RM, Moreira FC, de Moraes Filho MO, de Moraes MEA, de Souza LEB, Khayat AS, Moreira-Nunes CA. Circadian Rhythm Dysregulation and Leukemia Development: The Role of Clock Genes as Promising Biomarkers. Int J Mol Sci 2022; 23:ijms23158212. [PMID: 35897788 PMCID: PMC9332415 DOI: 10.3390/ijms23158212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/08/2022] [Accepted: 07/19/2022] [Indexed: 12/04/2022] Open
Abstract
The circadian clock (CC) is a daily system that regulates the oscillations of physiological processes and can respond to the external environment in order to maintain internal homeostasis. For the functioning of the CC, the clock genes (CG) act in different metabolic pathways through the clock-controlled genes (CCG), providing cellular regulation. The CC’s interruption can result in the development of different diseases, such as neurodegenerative and metabolic disorders, as well as cancer. Leukemias correspond to a group of malignancies of the blood and bone marrow that occur when alterations in normal cellular regulatory processes cause the uncontrolled proliferation of hematopoietic stem cells. This review aimed to associate a deregulated CC with the manifestation of leukemia, looking for possible pathways involving CG and their possible role as leukemic biomarkers.
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Affiliation(s)
- Ana Beatriz Aguiar Sanford
- Unichristus University Center, Faculty of Biomedicine, Fortaleza 60430-275, CE, Brazil; (A.B.A.S.); (L.S.d.C.)
| | - Leidivan Sousa da Cunha
- Unichristus University Center, Faculty of Biomedicine, Fortaleza 60430-275, CE, Brazil; (A.B.A.S.); (L.S.d.C.)
| | - Caio Bezerra Machado
- Pharmacogenetics Laboratory, Department of Medicine, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza 60430-275, CE, Brazil; (C.B.M.); (F.M.C.d.P.P.); (M.O.d.M.F.); (M.E.A.d.M.)
| | - Flávia Melo Cunha de Pinho Pessoa
- Pharmacogenetics Laboratory, Department of Medicine, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza 60430-275, CE, Brazil; (C.B.M.); (F.M.C.d.P.P.); (M.O.d.M.F.); (M.E.A.d.M.)
| | - Abigail Nayara dos Santos Silva
- Department of Biological Sciences, Oncology Research Center, Federal University of Pará, Belém 66073-005, PA, Brazil; (A.N.d.S.S.); (F.C.M.); (A.S.K.)
| | | | - Fabiano Cordeiro Moreira
- Department of Biological Sciences, Oncology Research Center, Federal University of Pará, Belém 66073-005, PA, Brazil; (A.N.d.S.S.); (F.C.M.); (A.S.K.)
| | - Manoel Odorico de Moraes Filho
- Pharmacogenetics Laboratory, Department of Medicine, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza 60430-275, CE, Brazil; (C.B.M.); (F.M.C.d.P.P.); (M.O.d.M.F.); (M.E.A.d.M.)
| | - Maria Elisabete Amaral de Moraes
- Pharmacogenetics Laboratory, Department of Medicine, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza 60430-275, CE, Brazil; (C.B.M.); (F.M.C.d.P.P.); (M.O.d.M.F.); (M.E.A.d.M.)
| | - Lucas Eduardo Botelho de Souza
- Center for Cell-Based Therapy, Regional Blood Center of Ribeirão Preto, University of São Paulo, São Paulo 14051-140, SP, Brazil;
| | - André Salim Khayat
- Department of Biological Sciences, Oncology Research Center, Federal University of Pará, Belém 66073-005, PA, Brazil; (A.N.d.S.S.); (F.C.M.); (A.S.K.)
| | - Caroline Aquino Moreira-Nunes
- Unichristus University Center, Faculty of Biomedicine, Fortaleza 60430-275, CE, Brazil; (A.B.A.S.); (L.S.d.C.)
- Pharmacogenetics Laboratory, Department of Medicine, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza 60430-275, CE, Brazil; (C.B.M.); (F.M.C.d.P.P.); (M.O.d.M.F.); (M.E.A.d.M.)
- Department of Biological Sciences, Oncology Research Center, Federal University of Pará, Belém 66073-005, PA, Brazil; (A.N.d.S.S.); (F.C.M.); (A.S.K.)
- Northeast Biotechnology Network (RENORBIO), Itaperi Campus, Ceará State University, Fortaleza 60740-903, CE, Brazil
- Correspondence:
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Circadian Clock Genes Act as Diagnostic and Prognostic Biomarkers of Glioma: Clinic Implications for Chronotherapy. BIOMED RESEARCH INTERNATIONAL 2022; 2022:9774879. [PMID: 35832846 PMCID: PMC9273445 DOI: 10.1155/2022/9774879] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/26/2022] [Accepted: 06/06/2022] [Indexed: 11/17/2022]
Abstract
Gliomas are the most common primary intracranial tumors and closely related to circadian clock. Due to the high mortality and morbidity of gliomas, exploring novel diagnostic and early prognostic markers is necessary. Circadian clock genes (CCGs) play important roles in regulating the daily oscillation of biological processes and the development of tumor. Therefore, we explored the influences that the oscillations of circadian clock genes (CCGs) on diagnosis and prognosis of gliomas using bioinformatics. In this work, we systematically analyzed the rhythmic expression of CCGs in brain and found that some CCGs had strong rhythmic expression; the expression levels were significantly different between day and night. Four CCGs (ARNTL, NPAS2, CRY2, and DBP) with rhythmic expression were not only identified as differentially expressed genes but also had significant independent prognostic ability in the overall survival of glioma patients and were highly correlated with glioma prognosis in COX analysis. Besides, we found that CCG-based predictive model demonstrated higher predictive accuracy than that of the traditional grade-based model; this new prediction model can greatly improve the accuracy of glioma prognosis. Importantly, based on the four CCGs’ circadian oscillations, we revealed that patients sampled at night had higher predictive ability. This may help detect glioma as early as possible, leading to early cancer intervention. In addition, we explored the mechanism of CCGs affecting the prognosis of glioma. CCGs regulated the cell cycle, DNA damage, Wnt, mTOR, and MAPK signaling pathways. In addition, it also affects prognosis through gene coexpression and immune infiltration. Importantly, ARNTL can rhythmically modulated the cellular sensitivity to clinic drugs, temozolomide. The optimal point of temozolomide administration should be when ARNTL expression is highest, that is, the effect is better at night. In summary, our study provided a basis for optimizing clinical dosing regimens and chronotherapy for glioma. The four key CCGs can serve as potential diagnostic and prognostic biomarkers for glioma patients, and ARNTL also has obvious advantages in the direction of glioma chronotherapy.
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Tischkau SA. Mechanisms of circadian clock interactions with aryl hydrocarbon receptor signalling. Eur J Neurosci 2019; 51:379-395. [DOI: 10.1111/ejn.14361] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 01/17/2019] [Accepted: 01/23/2019] [Indexed: 12/29/2022]
Affiliation(s)
- Shelley A. Tischkau
- Department of PharmacologySouthern Illinois University School of Medicine Springfield Illinois
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Morales-Santana S, Morell S, Leon J, Carazo-Gallego A, Jimenez-Lopez JC, Morell M. An Overview of the Polymorphisms of Circadian Genes Associated With Endocrine Cancer. Front Endocrinol (Lausanne) 2019; 10:104. [PMID: 30873119 PMCID: PMC6401647 DOI: 10.3389/fendo.2019.00104] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 02/04/2019] [Indexed: 12/17/2022] Open
Abstract
A major consequence of the world industrialized lifestyle is the increasing period of unnatural light in environments during the day and artificial lighting at night. This major change disrupts endogenous homeostasis with external circadian cues, which has been associated to higher risk of diseases affecting human health, mainly cancer among others. Circadian disruption promotes tumor development and accelerate its fast progression. The dysregulation mechanisms of circadian genes is greatly affected by the genetic variability of these genes. To date, several core circadian genes, also called circadian clock genes, have been identified, comprising the following: ARNTL, CLOCK, CRY1, CRY2, CSNK1E, NPAS2, NR1D1, NR1D2, PER1, PER2, PER3, RORA, and TIMELESS. The polymorphic variants of these circadian genes might contribute to an individual's risk to cancer. In this short review, we focused on clock circadian clock-related genes, major contributors of the susceptibility to endocrine-dependent cancers through affecting circadian clock, most likely affecting hormonal regulation. We examined polymorphisms affecting breast, prostate and ovarian carcinogenesis, in addition to pancreatic and thyroid cancer. Further study of the genetic composition in circadian clock-controlled tumors will be of great importance by establishing the foundation to discover novel genetic biomarkers for cancer prevention, prognosis and target therapies.
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Affiliation(s)
- Sonia Morales-Santana
- Proteomic Research Service, San Cecilio University Hospital, Instituto de Investigación Biosanitaria de Granada (Ibs.GRANADA), Granada, Spain
- *Correspondence: Sonia Morales-Santana
| | - Santiago Morell
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Santiago Morell
| | - Josefa Leon
- Clinical Management Unit of Digestive Disease, San Cecilio University Hospital, Instituto de Investigación Biosanitaria de Granada (Ibs.GRANADA), Granada, Spain
| | - Angel Carazo-Gallego
- Genomic Research Service, San Cecilio University Hospital, Instituto de Investigación Biosanitaria de Granada (Ibs.GRANADA), Granada, Spain
| | - Jose C. Jimenez-Lopez
- Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Spanish National Research Council (CSIC), Granada, Spain
- The UWA Institute of Agriculture and School of Agriculture and Environment, The University of Western Australia, Perth, WA, Australia
| | - María Morell
- Genomic Medicine Department, GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada, Andalusian Regional Government, PTS Granada, Granada, Spain
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A splice variant of human Bmal1 acts as a negative regulator of the molecular circadian clock. Exp Mol Med 2018; 50:1-10. [PMID: 30523262 PMCID: PMC6283877 DOI: 10.1038/s12276-018-0187-x] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 09/10/2018] [Accepted: 09/12/2018] [Indexed: 12/04/2022] Open
Abstract
Bmal1 is one of the key molecules that controls the mammalian molecular clock. In humans, two isoforms of Bmal1 are generated by alternative RNA splicing. Unlike the extensively studied hBmal1b, the canonical form of Bmal1 in most species, the expression and/or function of another human-specific isoform, hBmal1a, are poorly understood. Due to the lack of the N-terminal nuclear localization signal (NLS), hBMAL1a does not enter the nucleus as hBMAL1b does. However, despite the lack of the NLS, hBMAL1a still dimerizes with either hCLOCK or hBMAL1b and thereby promotes cytoplasmic retention or protein degradation, respectively. Consequently, hBMAL1a interferes with hCLOCK:hBMAL1b-induced transcriptional activation and the circadian oscillation of Period2. Moreover, when the expression of endogenous hBmal1a is aborted by CRISPR/Cas9-mediated knockout, the rhythmic expression of hPer2 and hBmal1b is restored in cultured HeLa cells. Together, these results suggest a role for hBMAL1a as a negative regulator of the mammalian molecular clock. An alternative form of a key ‘clock’ protein involved in the maintenance of daily cellular rhythms serves as a negative regulator of the cell’s 24-hour cycle. A team led by Ilmin Kwon from Sungkyunkwan University School of Medicine, Suwon, and Kyungjin Kim from Daegu Gyeongbuk Institute of Science and Technology, both in South Korea, detailed the function of BMAL1a, a lesser-studied variant of the clock protein BMAL1b, in human cells. Whereas BMAL1b enters the nucleus, where it works in concert with another protein called CLOCK to control circadian dynamics, BMAL1a stays in the cytoplasm, where it binds BMAL1b and CLOCK, interfering with their function. Genetically inhibiting BMAL1a helped restore normal rhythmic cycles. Drugs targeting BMAL1a may thus aid in sleep disorders and other circadian-linked health problems.
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Benna C, Helfrich-Förster C, Rajendran S, Monticelli H, Pilati P, Nitti D, Mocellin S. Genetic variation of clock genes and cancer risk: a field synopsis and meta-analysis. Oncotarget 2017; 8:23978-23995. [PMID: 28177907 PMCID: PMC5410358 DOI: 10.18632/oncotarget.15074] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/27/2016] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The number of studies on the association between clock genes’ polymorphisms and cancer susceptibility has increased over the last years but the results are often conflicting and no comprehensive overview and quantitative summary of the evidence in this field is available. RESULTS Literature search identified 27 eligible studies comprising 96756 subjects (cases: 38231) and investigating 687 polymorphisms involving 14 clock genes. Overall, 1025 primary and subgroup meta-analyses on 366 gene variants were performed. Study distribution by tumor was as follows: breast cancer (n=15), prostate cancer (n=3), pancreatic cancer (n=2), non-Hodgkin's lymphoma (n=2), glioma (n=1), chronic lymphocytic leukemia (n=1), colorectal cancer (n=1), non-small cell lung cancer (n=1) and ovarian cancer (n=1). We identified 10 single nucleotide polymorphisms (SNPs) significantly associated with cancer risk: NPAS2 rs10165970 (mixed and breast cancer shiftworkers), rs895520 (mixed), rs17024869 (breast) and rs7581886 (breast); CLOCK rs3749474 (breast) and rs11943456 (breast); RORA rs7164773 (breast and breast cancer postmenopausal), rs10519097 (breast); RORB rs7867494 (breast cancer postmenopausal), PER3 rs1012477 (breast cancer subgroups) and assessed the level of quality evidence to be intermediate. We also identified polymorphisms with lower quality statistically significant associations (n=30). CONCLUSIONS Our work supports the hypothesis that genetic variation of clock genes might affect cancer risk. These findings also highlight the need for more efforts in this research field in order to fully establish the contribution of clock gene variants to the risk of developing cancer. METHODS We conducted a systematic review and meta-analysis of the evidence on the association between clock genes’ germline variants and the risk of developing cancer. To assess result credibility, summary evidence was graded according to the Venice criteria and false positive report probability (FPRP) was calculated to further validate result noteworthiness. Subgroup meta-analysis was also performed based on participant features and tumor type. The breast cancer subgroup was further stratified by work conditions, estrogen receptor/progesterone receptor status and menopausal status, conditions associated with the risk of breast cancer in different studies.
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Affiliation(s)
- Clara Benna
- Department of Surgery Oncology and Gastroenterology, University of Padova, Padova, Italy
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Senthilkumar Rajendran
- Department of Surgery Oncology and Gastroenterology, University of Padova, Padova, Italy
| | | | | | - Donato Nitti
- Department of Surgery Oncology and Gastroenterology, University of Padova, Padova, Italy.,Clinica Chirurgica I, Azienda Ospedaliera Padova, Padova, Italy
| | - Simone Mocellin
- Department of Surgery Oncology and Gastroenterology, University of Padova, Padova, Italy.,Istituto Oncologico Veneto, IOV-IRCSS, Padova, Italy
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Jaeger C, Tischkau SA. Role of Aryl Hydrocarbon Receptor in Circadian Clock Disruption and Metabolic Dysfunction. ENVIRONMENTAL HEALTH INSIGHTS 2016; 10:133-141. [PMID: 27559298 PMCID: PMC4990151 DOI: 10.4137/ehi.s38343] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 07/12/2016] [Accepted: 07/14/2016] [Indexed: 06/01/2023]
Abstract
The prevalence of metabolic syndrome, a clustering of three or more risk factors that include abdominal obesity, increased blood pressure, and high levels of glucose, triglycerides, and high-density lipoproteins, has reached dangerous and costly levels worldwide. Increases in morbidity and mortality result from a combination of factors that promote altered glucose metabolism, insulin resistance, and metabolic dysfunction. Although diet and exercise are commonly touted as important determinants in the development of metabolic dysfunction, other environmental factors, including circadian clock disruption and activation of the aryl hydrocarbon receptor (AhR) by dietary or other environmental sources, must also be considered. AhR binds a range of ligands, which prompts protein-protein interactions with other Per-Arnt-Sim (PAS)-domain-containing proteins and subsequent transcriptional activity. This review focuses on the reciprocal crosstalk between the activated AhR and the molecular circadian clock. AhR exhibits a rhythmic expression and time-dependent sensitivity to activation by AhR agonists. Conversely, AhR activation influences the amplitude and phase of expression of circadian clock genes, hormones, and the behavioral responses of the clock system to changes in environmental illumination. Both the clock and AhR status and activation play significant and underappreciated roles in metabolic homeostasis. This review highlights the state of knowledge regarding how AhR may act together with the circadian clock to influence energy metabolism. Understanding the variety of AhR-dependent mechanisms, including its interactions with the circadian timing system that promote metabolic dysfunction, reveals new targets of interest for maintenance of healthy metabolism.
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Tong Y, Guo H, Brewer JM, Lee H, Lehman MN, Bittman EL. Expression of haPer1 and haBmal1 in Syrian Hamsters: Heterogeneity of Transcripts and Oscillations in the Periphery. J Biol Rhythms 2016; 19:113-25. [PMID: 15038851 DOI: 10.1177/0748730403262871] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The molecular biology of circadian rhythms has been extensively studied in mice, and the widespread expression of canonical circadian clock genes in peripheral organs is well established in this species. In contrast, much less information about the peripheral expression of haPer1, haPer2, and haBmal1 is available in Syrian hamsters despite the fact that this species is widely used for studies of circadian organization and photoperiodic responses. Furthermore, examination of oscillating expression of these genes in mouse testis has generated discrepant results, and little is known about gonadal expression of haPer1 and haBmal1 or their environmental control. To address these questions, the authors examined the pattern of haPer1 and haBmal1 in heart, kidney, liver, muscle, spleen, and testis of hamsters exposed to DD. In most organs, Northern blots suggested the existence of single transcripts of each of these messenger RNAs (mRNAs). haPer1 peaked in late subjective day and haBmal1 during the late subjective night. Closer inspection of SCN and muscle haPer1, however, revealed the existence of two major transcripts of similar size, as well as minor transcripts that varied in the 3′-untranslated region. In hamster testis, two haPer1 transcripts were found, both of which are truncated relative to the corresponding mouse transcript and both of which contain a sequence homologous to intron 18 of mPer1. Neither testis transcript contains a nuclear localization signal, and haPer1 transcripts lacked the putative C-terminal CRY1-binding domain. Furthermore, the testis deviated from the general pattern in that haPer1 and haBmal1 both peaked in the subjective night. In situ hybridization revealed that haPer1, but not haBmal1, showed a heterogeneous distribution among seminiferous tubules. Hamster testis also expresses 2 haPer2 transcripts, but no circadian variation is evident. In a second experiment, long-term exposure to DD sufficient to induce gonadal regression was found to eliminate circadian oscillations of both testicular haPer1 transcripts. In contrast, gonadal regression was accompanied by a more robust rhythm of haBmal1.
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Affiliation(s)
- Yanhong Tong
- Center for Neuroendocrine Studies, Program in Neuroscience and Behavior, and Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
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Stevens RG, Zhu Y. Electric light, particularly at night, disrupts human circadian rhythmicity: is that a problem? Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2014.0120. [PMID: 25780233 DOI: 10.1098/rstb.2014.0120] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Over the past 3 billion years, an endogenous circadian rhythmicity has developed in almost all life forms in which daily oscillations in physiology occur. This allows for anticipation of sunrise and sunset. This physiological rhythmicity is kept at precisely 24 h by the daily cycle of sunlight and dark. However, since the introduction of electric lighting, there has been inadequate light during the day inside buildings for a robust resetting of the human endogenous circadian rhythmicity, and too much light at night for a true dark to be detected; this results in circadian disruption and alters sleep/wake cycle, core body temperature, hormone regulation and release, and patterns of gene expression throughout the body. The question is the extent to which circadian disruption compromises human health, and can account for a portion of the modern pandemics of breast and prostate cancers, obesity, diabetes and depression. As societies modernize (i.e. electrify) these conditions increase in prevalence. There are a number of promising leads on putative mechanisms, and epidemiological findings supporting an aetiologic role for electric lighting in disease causation. These include melatonin suppression, circadian gene expression, and connection of circadian rhythmicity to metabolism in part affected by haem iron intake and distribution.
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Affiliation(s)
- Richard G Stevens
- Department of Community Medicine, University of Connecticut Health Center, Farmington, CT, USA
| | - Yong Zhu
- Department of Environmental Health Sciences, Yale University, New Haven, CT, USA
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Ziv-Gal A, Flaws JA, Mahoney MM, Miller SR, Zacur HA, Gallicchio L. Genetic polymorphisms in the aryl hydrocarbon receptor-signaling pathway and sleep disturbances in middle-aged women. Sleep Med 2013; 14:883-7. [PMID: 23768840 DOI: 10.1016/j.sleep.2013.04.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 04/02/2013] [Accepted: 04/05/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE We aimed to determine if selected genetic polymorphisms in the aryl hydrocarbon receptor (AHR)-signaling pathway and circadian locomotor output cycles kaput (CLOCK) are associated with insomnia and early awakening in middle-aged women. METHODS Women aged 45 to 54years (n=639) were recruited into a middle-aged health study and agreed to complete questionnaires and donate blood samples. Questionnaires were used to assess sleep outcomes. Blood samples were processed for genotyping for the selected polymorphisms: AHR (rs2066853), AHR repressor (AHRR) (rs2292596), aryl hydrocarbon nuclear translocator (ARNT) (rs2228099), and CLOCK (rs1801260). Data were analyzed using multivariable logistic regression. RESULTS Women heterozygous for the AHRR alleles (GC) had decreased odds of insomnia compared to women homozygous for the AHRR_C allele (adjusted odds ratio [aOR], 0.69; 95% confidence interval [CI], 0.49-0.96). Women with at least one of the AHRR_G or CLOCK_C alleles had significantly decreased odds of insomnia compared to women homozygous for the AHRR_C and CLOCK_T alleles (aOR, 0.64; 95% CI, 0.43-0.96). Additionally, women homozygous for the AHRR_G and CLOCK_C alleles had significantly decreased odds of insomnia compared to women homozygous for the AHRR_C and CLOCK_T alleles (aOR, 0.56; 95% CI, 0.35-0.89). None of the selected single nucleotide polymorphisms (SNPs) or combinations of SNPs were significantly associated with early awakening. CONCLUSIONS Selected genetic polymorphisms in the AHR-signaling pathway (i.e., AHRR) and CLOCK may play a role in decreasing the risk for experiencing insomnia during the menopausal transition.
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Affiliation(s)
- Ayelet Ziv-Gal
- Comparative Biosciences, University of Illinois, Urbana, IL, USA
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Zhu Y, Fu A, Hoffman AE, Figueiro MG, Carskadon MA, Sharkey KM, Rea MS. Advanced sleep schedules affect circadian gene expression in young adults with delayed sleep schedules. Sleep Med 2013; 14:449-55. [PMID: 23562184 DOI: 10.1016/j.sleep.2012.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 11/30/2012] [Accepted: 12/17/2012] [Indexed: 01/09/2023]
Abstract
BACKGROUND Human circadian rhythms are regulated by the interplay between circadian genes and environmental stimuli. The influence of altered sleep-wake schedules or light on human circadian gene expression patterns is not well characterized. METHODS Twenty-one young adults were asked to keep to their usual sleep schedules and two blood samples were drawn at the end of the first week from each subject based on estimated time of dim light melatonin onset (DLMO); the first sample was obtained one and a half hours before the estimated DLMO and the second three hours later, at one and a half hours after the estimated DLMO. During the second week, participants were randomized into two groups, one that received a one hour blue-light (λmax=470 nm) exposure in the morning and one that received a comparable morning dim-light exposure. Two blood samples were obtained at the same clock times as the previous week at the end of the second week. RESULTS We measured the expression of 10 circadian genes in response to sleep-wake schedule advancement and morning blue-light stimulation in the peripheral blood of 21 participants during a two-week field study. We found that nine of the 10 circadian genes showed significant expression changes from the first to the second week for participants in both the blue-light and dim-light groups, likely reflecting significant advances in circadian phase. CONCLUSIONS This wholesale change in circadian gene expression may reflect considerable advances in circadian phase (i.e., advance in DLMO) from the first to the second week resulting from the advanced, daily personal light exposures.
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Affiliation(s)
- Yong Zhu
- School of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT, USA.
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13
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Bae JH, Ahn K, Nam GH, Lee CE, Park KD, Lee HK, Cho BW, Kim HS. Molecular characterization of alternative transcripts of the horse BMAL1 gene. Zoolog Sci 2011; 28:671-5. [PMID: 21882956 DOI: 10.2108/zsj.28.671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The horse BMAL1 gene encodes the brain and muscle Arnt-like protein 1, which is a key regulator of circadian rhythmic systems in most organs and cells. The first exon of the horse-specific BMAL1 gene is produced by an exonization event of LINE3 (CR1) and SINE (MIR) was detected by bioinformatic analysis. Alternative variants generated by cassette exon event in various horse tissues were also detected by RT-PCR amplification and sequencing. The cDNA sequences of the horse transcripts (BMAL1a, BMAL1b) contain additional 21 bp and 71 bp fragments relative to horse BMAL1. Quantitative real-time RT-PCR was performed to compare the expression patterns between transcript variants in various horse tissues. The results of these experiments showed splice variants that were widely expressed in most tissues. Furthermore, they were highly expressed in cerebellum, heart, and kidney.
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Affiliation(s)
- Jin-Han Bae
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea
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Ma Q. Influence of light on aryl hydrocarbon receptor signaling and consequences in drug metabolism, physiology and disease. Expert Opin Drug Metab Toxicol 2011; 7:1267-93. [DOI: 10.1517/17425255.2011.614947] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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15
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Tischkau SA, Jaeger CD, Krager SL. Circadian clock disruption in the mouse ovary in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol Lett 2011; 201:116-22. [PMID: 21182907 PMCID: PMC3039055 DOI: 10.1016/j.toxlet.2010.12.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 12/13/2010] [Accepted: 12/14/2010] [Indexed: 12/29/2022]
Abstract
Activation of the aryl hydrocarbon receptor (AhR) by the highly toxic, prototypical ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or other dioxin-like compounds compromises ovarian function by altering follicle maturation and steroid synthesis. Although alteration of transcription after nuclear translocation and heterodimerization of AhR with its binding partner, aryl hydrocarbon nuclear transporter (ARNT), is often cited as a primary mechanism for mediating the toxic effects of dioxins, recent evidence indicates that crosstalk between AhR and several other signaling pathways also occurs. Like the circadian clock genes, AhR is a member of the basic helix-loop-helix, Per-ARNT-SIM (bHLH-PAS) domain family of proteins. Thus, these studies tested the hypothesis that TCDD can act to alter circadian clock regulation in the ovary. Adult female c57bl6/J mice entrained to a typical 12h light/12h dark cycle were exposed to a single 1 μg/kg dose of TCDD by gavage. Six days after exposure, animals were released into constant darkness and ovaries were collected every 4h over a 24h period. Quantitative real-time PCR and immunoblot analysis demonstrated that TCDD exposure alters expression of the canonical clock genes, Bmal1 and Per2 in the ovary. AhR transcript and protein, which displayed a circadian pattern of expression in the ovaries of control mice, were also altered after TCDD treatment. Immunohistochemistry studies revealed co-localization of AhR with BMAL1 in various ovarian cell types. Furthermore, co-immunoprecipitation demonstrated time-of-day dependent interactions of AhR with BMAL1 that were enhanced after TCDD treatment. Collectively these studies suggest that crosstalk between classical AhR signaling and the molecular circadian clockworks may be responsible for altered ovarian function after TCDD exposure.
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Affiliation(s)
- Shelley A Tischkau
- Department of Pharmacology, Southern Illinois University, School of Medicine, 801N. Rutledge, Springfield, IL 62794-9629, USA.
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16
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Molecular characterization and chromosomal mapping of porcine brain and muscle Arnt-like protein-1 gene. Mol Biol Rep 2009; 36:2423-30. [PMID: 19247803 DOI: 10.1007/s11033-009-9473-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 02/17/2009] [Indexed: 10/21/2022]
Abstract
As a transcription factor regulating circadian rhythm, brain and muscle Arnt-like protein-1 (BMAL1) plays an important role in lipid homeostasis. The Chinese indigenous and western pig breeds show marked difference in fat deposition, the structure and function of porcine BMAL1 (pBMAL1) between them might be different. In present study, the molecular characteristics and chromosomal location of pBMAL1 were analyzed. The results indicated that pBMAL1 cDNA had a coding region of 1,878 bp and shared 94.36, 89.85 and 89.79% identity with human, mouse and rat BMAL1, respectively, and the pBMAL1 protein had 99.20, 98.24 and 97.92% identity to those of human BMAL1b, mouse BMAL1b and rat BMAL1b, respectively. Compared with other mammals, pBMAL1 was more closely related to human BMAL1. The expression of pBMAL1 was detected in kidney, stomach, spleen, bladder, gallbladder, lumbar spinal cord, medulla oblongata, heart, longissimus dorsi muscle, liver, small intestine, large intestine, lung and backfat tissues. In adipose tissues, it was detected in mesentery fat, leaf fat, caul fat, backfat and cardiac fat, however, the expression level was not significantly different. Alternative usage of exon 2 was revealed to result in two pBMAL1 transcripts. Finally, by using a whole genome porcine radiation hybrid (RH) panel (IMpRH), the pBMAL1 gene was mapped to SSC 2p11-q21.
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17
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Shimba S, Watabe Y. Crosstalk between the AHR signaling pathway and circadian rhythm. Biochem Pharmacol 2009; 77:560-5. [DOI: 10.1016/j.bcp.2008.09.040] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 09/25/2008] [Accepted: 09/26/2008] [Indexed: 01/28/2023]
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18
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Shao QM, Bembenek J, Trang LTD, Hiragaki S, Takeda M. Molecular structure, expression patterns, and localization of the circadian transcription modulator CYCLE in the cricket, Dianemobius nigrofasciatus. JOURNAL OF INSECT PHYSIOLOGY 2008; 54:403-413. [PMID: 18082762 DOI: 10.1016/j.jinsphys.2007.10.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Revised: 10/23/2007] [Accepted: 10/24/2007] [Indexed: 05/25/2023]
Abstract
CYCLE (CYC), also known as BMAL1 in vertebrate nomenclature, is a transcription modulator of the circadian genes period and timeless of Drosophila melanogaster. We cloned a cDNA encoding a CYC homologue from the head of the ground cricket, Dianemobius nigrofasciatus (Dncyc), the first CYC from Hemimetabola. The deduced sequence corresponded to a 601 amino-acid polypeptide, with well-defined bHLH, PAS-A, PAS-B, PAC, and BTCR domains. The amino-acid sequence showed 70.7% identity with the CYC protein of Athalia rosae, 63.8% with D. melanogaster, and 52% identity with the human homologue. A cyc transcript of around 3.6kb occurs in the brain, midgut, testis, fatbody, and muscle. An additional band of around 1.1kb gave a hybridization signal in the head. No temporal oscillation in cyc mRNA abundance was observed in the head of the adult cricket when investigated by Northern blot analysis. CYC-like immunohistochemical reactivity (ir) and its dimerization partner CLOCK (CLK)-ir appeared in the pars intercerebralis (PI), tritocerebrum, dorsolateral protocerebrum, and subesophageal ganglion (SOG), but no CYC-ir was observed in the optic lobe (OL) that showed CLK-ir. The deutocerebrum showed a unique CLK-ir but no CYC-ir pattern. Double-labelling experiments showed that both antigens were co-localized in the mandibular and maxillary neuromeres of the SOG. CYC-ir showed no daily oscillation in intensity and the staining pattern was always cytoplasmic. CLK-ir occurred in the nucleus at ZT 16, but was cytoplasmic at other ZT times. A neuronal network equivalent to adult system occurred in the second nymphal stadium.
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Affiliation(s)
- Qi-Miao Shao
- Division of Molecular Science, Graduate School of Science and Technology, Kobe University, Kobe, Japan
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19
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Alvarez JD, Hansen A, Ord T, Bebas P, Chappell PE, Giebultowicz JM, Williams C, Moss S, Sehgal A. The circadian clock protein BMAL1 is necessary for fertility and proper testosterone production in mice. J Biol Rhythms 2008; 23:26-36. [PMID: 18258755 PMCID: PMC2862364 DOI: 10.1177/0748730407311254] [Citation(s) in RCA: 198] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although it is well established that the circadian clock regulates mammalian reproductive physiology, the molecular mechanisms by which this regulation occurs are not clear. The authors investigated the reproductive capacity of mice lacking Bmal1 (Arntl, Mop3), one of the central circadian clock genes. They found that both male and female Bmal1 knockout (KO) mice are infertile. Gross and microscopic inspection of the reproductive anatomy of both sexes suggested deficiencies in steroidogenesis. Male Bmal1 KO mice had low testosterone and high luteinizing hormone serum concentrations, suggesting a defect in testicular Leydig cells. Importantly, Leydig cells rhythmically express BMAL1 protein, suggesting peripheral control of testosterone production by this clock protein. Expression of steroidogenic genes was reduced in testes and other steroidogenic tissues of Bmal1 KO mice. In particular, expression of the steroidogenic acute regulatory protein (StAR) gene and protein, which regulates the rate-limiting step of steroidogenesis, was decreased in testes from Bmal1 KO mice. A direct effect of BMAL1 on StAR expression in Leydig cells was indicated by in vitro experiments showing enhancement of StAR transcription by BMAL1. Other hormonal defects in male Bmal1 KO mice suggest that BMAL1 also has functions in reproductive physiology outside of the testis. These results enhance understanding of how the circadian clock regulates reproduction.
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Affiliation(s)
- J. D. Alvarez
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Amanda Hansen
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Teri Ord
- Center for Research on Reproduction and Women’s Health, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Piotr Bebas
- Department of Animal Physiology, University of Warsaw, Poland
- Department of Zoology, Oregon State University, Corvallis, OR
| | | | | | - Carmen Williams
- Center for Research on Reproduction and Women’s Health, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Stuart Moss
- Center for Research on Reproduction and Women’s Health, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Amita Sehgal
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA
- Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, PA
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20
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Mukai M, Tischkau SA. Effects of tryptophan photoproducts in the circadian timing system: searching for a physiological role for aryl hydrocarbon receptor. Toxicol Sci 2006; 95:172-81. [PMID: 17020875 DOI: 10.1093/toxsci/kfl126] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) mediates adverse effects of dioxins, but its physiological role remains ambiguous. The similarity between AhR and canonical circadian clock genes suggests potential involvement of AhR in regulation of circadian timing. Photoproducts of tryptophan (TRP), including 6-formylindolo[3,2-b]carbazole (FICZ), have high affinity for AhR and are postulated as endogenous ligands. Although TRP photoproducts activate AhR signaling in vitro, their effects in vivo have not been investigated in mammals. Because TRP photoproducts may act as transducers of light, we examined their effects on the circadian clock. Intraperitoneal injection of TRP photoproducts or FICZ to C57BL/6J mice dose dependently induced AhR downstream targets, cytochrome P4501A1 (CYP1A1) and cytochrome P4501B1 mRNA expression, in liver. c-fos mRNA, a commonly used marker for light responses, was also induced with FICZ, and all responses were AhR dependent. A rat-immortalized suprachiasmatic nucleus (SCN) cell line, SCN 2.2, was used to examine the direct effect of TRP photoproducts on the molecular clock. Both TRP photoproducts and FICZ-increased CYP1A1 expression and prolonged FICZ incubation altered the circadian expression of clock genes (Per1, Cry1, and Cry2) in SCN 2.2 cells. Furthermore, FICZ inhibited glutamate-induced phase shifting of the mouse SCN electrical activity rhythm. Circadian light entrainment is critical for adjustment of the endogenous rhythm to environmental light cycle. Our results reveal a potential for TRP photoproducts to modulate light-dependent regulation of circadian rhythm through triggering of AhR signaling. This may lead to further understanding of toxicity of dioxins and the role of AhR in circadian rhythmicity.
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Affiliation(s)
- Motoko Mukai
- Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
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21
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Harms E, Kivimäe S, Young MW, Saez L. Posttranscriptional and posttranslational regulation of clock genes. J Biol Rhythms 2005; 19:361-73. [PMID: 15534317 DOI: 10.1177/0748730404268111] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Circadian rhythms have been observed in diverse organisms, including plants, animals, bacteria, and fungi. In such organisms, the circadian clock is primarily composed of a cell-autonomous transcriptional feedback loop. In addition to transcriptional regulation, the modification of core clock transcripts and proteins can dramatically affect the circadian clock. In this review, the authors discuss some of the posttranscriptional and posttranslational modifications and their effects on the circadian clock. The combined outcome of these modifications is to adjust the timing of the clock to produce a circadian oscillator that takes approximately 24 h.
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Affiliation(s)
- Emily Harms
- Laboratory of Genetics, Rockefeller University, New York, NY 10021, USA
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22
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Sato F, Kawamoto T, Fujimoto K, Noshiro M, Honda KK, Honma S, Honma KI, Kato Y. Functional analysis of the basic helix-loop-helix transcription factor DEC1 in circadian regulation. Interaction with BMAL1. EUROPEAN JOURNAL OF BIOCHEMISTRY 2004; 271:4409-19. [PMID: 15560782 DOI: 10.1111/j.1432-1033.2004.04379.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The basic helix-loop-helix transcription factor DEC1 is expressed in a circadian manner in the suprachiasmatic nucleus where it seems to play a role in regulating the mammalian circadian rhythm by suppressing the CLOCK/BMAL1-activated promoter. The interaction of DEC1 with BMAL1 has been suggested as one of the molecular mechanisms of the suppression [Honma, S., Kawamoto, T., Takagi, Y., Fujimoto, K., Sato, F., Noshiro, M., Kato, Y. & Honma, K. (2002) Nature 419, 841-844]. Deletion analysis of DEC1 demonstrated that its N-terminal region, which includes the basic helix-loop-helix domain, was essential for both the suppressive activity and the interaction with BMAL1, as DEC1 lacking the basic region did not show any suppression or interaction. Furthermore, we found that Arg65 in the basic region, which is conserved among group B basic helix-loop-helix proteins, was responsible for the suppression, for the interaction with BMAL1 and for its binding to CACGTG E-boxes. However, substitution of His57 for Ala significantly reduced the E-box binding activity of DEC1, although it did not affect the interaction with BMAL1 or suppression of CLOCK/BMAL1-induced transcription. On the other hand, the basic region-deleted DEC1 acted in a dominant-negative manner for DEC1 activity, indicating that the basic region was not required for homodimer formation of DEC1. Moreover, mutant DEC1 also counteracted DEC2-mediated suppressive activity in a dominant-negative manner. The heterodimer formation of DEC1 and DEC2 was confirmed by pull-down assay. These findings suggest that the basic region of DEC1 participates in the transcriptional regulation through a protein-protein interaction with BMAL1 and DNA binding to the E-box.
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Affiliation(s)
- Fuyuki Sato
- Department of Dental and Medical Biochemistry, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan
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23
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Chilov D, Fussenegger M. Toward construction of a self-sustained clock-like expression system based on the mammalian circadian clock. Biotechnol Bioeng 2004; 87:234-42. [PMID: 15236253 DOI: 10.1002/bit.20143] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Despite recent advances in circadian biology, detailed understanding of how a biological pacemaker system is assembled, maintained, and regulated continues to be a significant challenge. We have assembled and characterized a first-generation, regulatable, self-sustained clock-like expression system based on key components of the mammalian circadian clock. The molecular setup of the clock-like oscillator was reduced to the core set of positive and negative elements common to all known circadian pacemakers. Sophisticated tetracycline-responsive multi-cistronic expression integrated with forefront lentiviral transduction tools enabled autoregulated reporter transgene expression in a human cell line. We characterized transgene expression kinetics of an artificial oscillator and showed that its expression profiles could be modulated by a serum shock and administration of regulating tetracycline antibiotics. Design of a generic mammalian clock-like expression system will offer novel opportunities to study circadian biology and may provide a unique tool for rhythmic expression of desired transgenes fostering advances in biopharmaceutical manufacturing, gene therapy, and tissue engineering.
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Affiliation(s)
- Dmitri Chilov
- Institute of Biotechnology, Swiss Federal Institute of Technology, ETH Hoenggerberg, HPT D74, CH-8093 Zurich, Switzerland
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24
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Fidler AE, Gwinner E. Comparative analysis of Avian BMAL1 and CLOCK protein sequences: a search for features associated with owl nocturnal behaviour. Comp Biochem Physiol B Biochem Mol Biol 2003; 136:861-74. [PMID: 14662308 DOI: 10.1016/s1096-4959(03)00276-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Animals differ widely in the phasing of their daily rhythms with respect to daily environmental rhythms. While birds are predominantly day-active, nocturnal activity is a characteristic feature of the order Strigiformes (owls). To study the evolution of owl night-activity cDNA sequences encoding the circadian core oscillator (CCO) proteins BMAL1 and CLOCK were obtained from barn owl (Tyto alba). The predicted proteins showed high sequence identity with their Galliform homologues (BMAL1: 99%; CLOCK: 95.6%). A computer-predicted chicken BMAL1 casein kinase-1 phosphorylation site is absent from T. alba BMAL1, but also absent from homologues of other six bird species (5 orders) (night-active (n=2), day-active (n=4)) indicating no evolutionary association with night activity. Sequence differences between T. alba and Galliform CLOCK frequently involved serine and threonine residues suggesting potential differences in their phosphorylation. The length of a poly-glutamine string in the CLOCK C-terminus varied between and within 25 species (6 orders) examined, however, no discernible feature distinguishing day and night active species was found. No differences were found between day (n=5) and night (n=7)-active species (12 species, 6 orders) in a region of the PER2 protein implicated in altered rhythm phasing in humans. In conclusion the avian CCO components examined showed strong evolutionary conservation. Molecular evolution associated with owl night-activity may have involved alterations in the CCO relationship with 'output' genes rather than in the molecular structure of the CCO itself.
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Affiliation(s)
- Andrew E Fidler
- Max-Planck Research Center for Ornithology, Seewiesen and Andechs, Postfach 1564, D-82319 Starnberg, Germany.
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25
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Chong NW, Chaurasia SS, Haque R, Klein DC, Iuvone PM. Temporal-spatial characterization of chicken clock genes: circadian expression in retina, pineal gland, and peripheral tissues. J Neurochem 2003; 85:851-60. [PMID: 12716417 DOI: 10.1046/j.1471-4159.2003.01723.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The molecular core of the vertebrate circadian clock is a set of clock genes, whose products interact to control circadian changes in physiology. These clock genes are expressed in all tissues known to possess an endogenous self-sustaining clock, and many are also found in peripheral tissues. In the present study, the expression patterns of two clock genes, cBmal1 and cMOP4, were examined in the chicken, a useful model for analysis of the avian circadian system. In two tissues which contain endogenous clocks--the pineal gland and retina--circadian fluctuations of both cBmal1 and cMOP4 mRNAs were observed to be synchronous; highest levels occurred at Zeitgeber time 12. Expression of these genes is also rhythmic in several peripheral tissues; however, the phases of these rhythms differ from those in the pineal gland and retina: in the liver the peaks of cMOP4 and cBmal1 mRNAs are delayed 4-8 h and in the heart they are advanced by 4 h, relative to those in the pineal gland and retina. These results provide the first temporal characterization of cBmal1 and cMOP4 mRNAs in avian tissues: their presence in avian peripheral tissues indicates they may influence temporal features of daily rhythms in biochemical, physiological, and behavioral functions at these sites.
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Affiliation(s)
- Nelson W Chong
- Division of Cardiology, Department of Medicine, Glenfield General Hospital, Clinical Sciences Wing, University of Leicester, Leicester LE3 9QP, UK.
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26
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Korkalainen M, Tuomisto J, Pohjanvirta R. Identification of novel splice variants of ARNT and ARNT2 in the rat. Biochem Biophys Res Commun 2003; 303:1095-100. [PMID: 12684048 DOI: 10.1016/s0006-291x(03)00489-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Most of the biochemical and toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are mediated by the bHLH/PAS protein AH receptor (AHR). For regulation of gene activities, AHR dimerizes with another member of the bHLH/PAS protein family, AHR nuclear translocator (ARNT). A substrain of Wistar rats, Han/Wistar (Kuopio) (H/W), is about 1000-fold more resistant to the acute lethality of TCDD than other strains, exemplified by Long-Evans (Turku/AB) (L-E); the LD50 values for these two strains are >9600 and 10-20 microg/kg, respectively. Previous studies have demonstrated that the major reason for the exceptional TCDD resistance of H/W rats lies in their AHR, which is remodeled at its C-terminal transactivation domain, but there appears to be another contributing gene product. The present study set out to compare the primary structure of ARNT and the closely related ARNT2 proteins in H/W and L-E rats by cDNA cloning. To our surprise, we found several isoforms of these proteins only one of which has previously been reported in rats. All of the isoforms appeared to arise from alternative splicing. For ARNT, isoforms with deletions at exon 5, 3(') end of exon 6 or 5(') end of exon 11, or with an insertion at 5(') end of exon 20 were discovered. There was also interindividual variation in the number of glutamine-encoding codons at 5(') end of exon 16. The most exciting new variant was revealed for ARNT2, because the insertion found at 5(') end of exon 19 disrupts the functionally critical transactivation domain in the protein, implying a dominant negative role for this isoform. The relative expression levels of the variants did not differ in the two rat strains, nor did TCDD modify the ratios, suggesting that the variants do not contribute to TCDD resistance. However, the regulation of ARNT and ARNT2 activities may be more intricate than previously assumed.
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Affiliation(s)
- Merja Korkalainen
- National Public Health Institute, Laboratory of Toxicology, Department of Environmental Health, P.O. Box 95, Neulaniementie 4, FIN-70701 Kuopio, Finland.
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27
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Markova EP, Ueda H, Sakamoto K, Oishi K, Shimada T, Takeda M. Cloning of Cyc (Bmal1) homolog in Bombyx mori: structural analysis and tissue specific distributions. Comp Biochem Physiol B Biochem Mol Biol 2003; 134:535-42. [PMID: 12628385 DOI: 10.1016/s1096-4959(03)00004-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Cycle (Bmal1) is one of the circadian clock genes and the key regulator of the circadian system in many organisms, encoding a bHLH-PAS transcription factor. In the present study, we cloned cycle homolog (BmCyc) in Bombyx mori. We performed polymerase chain reaction with degenerated primers deduced from the conserved amino acid sequences of mammalian BMAL1 and Drosophila CYCLE. Then the partial clone obtained was used as a probe for screening a cDNA library constructed from pupal brains of B. mori. BmCyc is 5703 nucleotides long and encodes 700 amino acid residues. The BmCYC has bHLH, PAS A and PAS B domains, and the sequence identities for these domains are 85, 60 and 50%, to Drosophila CYCLE (dCYC) and 69, 58 and 50%, to human BMAL1 (hBMAL1), respectively. The deduced amino acid sequence of BmCYC is 37% identical to that of dCYC and 28% to hBMAL1. Northern blot analysis demonstrates that BmCyc gene was expressed in all the tissues tested, which were head, fat body, silk glands, and midgut. Also no significant day, night time-specific difference in expression of BmCyc gene in the head was detected.
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Affiliation(s)
- Elitza P Markova
- Division of Molecular Science, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
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28
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Schoenhard JA, Eren M, Johnson CH, Vaughan DE. Alternative splicing yields novel BMAL2 variants: tissue distribution and functional characterization. Am J Physiol Cell Physiol 2002; 283:C103-14. [PMID: 12055078 DOI: 10.1152/ajpcell.00541.2001] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The BMAL2 gene encodes a member of the basic helix-loop-helix PER-ARNT-SIM family of transcription factors, which control diverse physiological processes including circadian rhythms. We identified four novel human BMAL2 transcripts that differ by alternative splicing within their NH2-terminal regions. Divergent expression of these and previously reported transcripts was observed among human tissues. The functional consequences of alternative splicing for transcriptional activation by CLOCK:BMAL2 heterodimers were assessed using luciferase reporter gene constructs that contained one of three diurnally regulated promoters, namely, those of the mouse period1, mouse vasopressin, and human plasminogen activator inhibitor-1 genes. These studies revealed that alternative splicing generates BMAL2 isoforms possessing high, medium, low, or no transcriptional activity. Similar results were obtained with each promoter, suggesting that alternative splicing may influence the amplitudes of both central and peripheral oscillators. Indeed, alternative splicing of BMAL2 may provide tissues with a rheostat capable of regulating CLOCK:BMAL2 heterodimer function across a broad continuum of potential transcriptional activities to accommodate varied metabolic demands and physiological roles.
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Affiliation(s)
- John A Schoenhard
- Division of Cardiovascular Medicine, Departments of Medicine and Pharmacology, Vanderbilt University, Tennessee 37235, USA
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29
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Johnson MH, Lim A, Fernando D, Day ML. Circadian clockwork genes are expressed in the reproductive tract and conceptus of the early pregnant mouse. Reprod Biomed Online 2002; 4:140-5. [PMID: 12470576 DOI: 10.1016/s1472-6483(10)61931-1] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Circadian genes are expressed in some peripheral tissues, but the expression status of the female reproductive tract and the conceptus over the preimplantation period is unknown. Oocytes, uterine, oviducal tissues and preimplantation conceptuses from days 1-4 of mouse pregnancy were analysed for transcript presence by reverse transcription polymerase chain reaction. Transcripts encoded by the seven known mammalian canonical circadian genes (Per1-3, Cry1-2, Bmal1 and Clock), plus the mammalian genetic homologue of the Drosophila canonical gene Timeless, were detected in the uteri and oviducts taken from mice on days 1-4 of pregnancy and in unfertilized oocytes. After fertilization, transcripts for Per1, Cry1, Bmal1, Clock and Tim have been detected unambiguously. Transcript levels for each of these five genes fall at the two-cell stage, but are restored rapidly for Per1, Cry1 and Bmal1, presumptively by zygotic gene expression. In contrast, transcripts for Clock and Tim recover more slowly. It is concluded that circadian genes are expressed, and may therefore have a role, during the early development of the mammal.
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Affiliation(s)
- Martin H Johnson
- Department of Physiology (F13), University of Sydney, NSW 2006, Australia.
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Yu W, Nomura M, Ikeda M. Interactivating feedback loops within the mammalian clock: BMAL1 is negatively autoregulated and upregulated by CRY1, CRY2, and PER2. Biochem Biophys Res Commun 2002; 290:933-41. [PMID: 11798163 DOI: 10.1006/bbrc.2001.6300] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transcriptional regulation appears to be fundamental to circadian oscillations of clock gene expression. These oscillations are believed to control output rhythms. The transcriptional feedback loop and a model of interlocked loops have been proposed as the basis for these oscillations. We characterized the genomic structure of the mouse Bmal1 gene (mBmal1) and defined the mBmal1 promoter region. Transcription of mBmal1 was activated by CRY1, CRY2, and PER2, and was repressed by BMAL1-CLOCK dimers. Therefore, CRY, PER2, and BMAL1-CLOCK play bidirectional roles in transcription when they are at high levels by late day and midnight, respectively. This underlies the opposite phase of BMAL1 compared to CRY and PER. We propose that a BMAL1 negative feedback loop interlocks with the CRY and PER2 negative feedback loop by inter-activation, forming a third positive forward loop. This transcriptional model suggests a molecular basis for the maintenance of stability, persistence, and period of circadian rhythms. The transcriptional potency of CRY is predominant within the mammalian clock, suggesting a clearance mechanism for CRY in period maintenance. (c)2002 Elsevier Science (USA).
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Affiliation(s)
- Wangjie Yu
- Department of Physiology, Saitama Medical School, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan
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31
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Light and glutamate-induced degradation of the circadian oscillating protein BMAL1 during the mammalian clock resetting. J Neurosci 2001. [PMID: 11027210 DOI: 10.1523/jneurosci.20-20-07525.2000] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Recently discovered mammalian clock genes are believed to compose the core oscillator, which generates the circadian rhythm. BMAL1/CLOCK heterodimer is the essential positive element that drives clock-related transcription and self-sustaining oscillation by a negative feedback mechanism. We examined BMAL1 protein expression in the rat suprachiasmatic nuclei (SCN) by immunoblot analysis. Anti-BMAL1 antiserum raised against rBMAL1 recognized 70 kDa mBMAL1b and detected a similar immunoreactivity (IR) as a major band in rat brains. Robust circadian BMAL1-IR oscillations with nocturnal peaks were detected in the SCN during a light/dark cycle and under constant darkness. A short duration light exposure at night acutely reduced BMAL1-IR in the SCN during photoentrainment. This might be attributable to the degradation of BMAL1 protein. Application of glutamate and NMDA to the SCN slices at projected night, a procedure mimicking photic phase delay shift, also acutely reduced BMAL1-IR in a similar manner. A rapid decrease of BMAL1 protein suggests that BMAL1 protein might be implicated in the light-transducing pathway within the SCN.
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Hsu HJ, Wang WD, Hu CH. Ectopic expression of negative ARNT2 factor disrupts fish development. Biochem Biophys Res Commun 2001; 282:487-92. [PMID: 11401485 DOI: 10.1006/bbrc.2001.4525] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
ARNT factors are a cluster of bHLH-PAS factors that heterodimerize with other specific bHLH-PAS factors to mediate a wide range of biological responses. Previously, we obtained a truncated form of ARNT2-like factor, ARNT2A, from zebrafish, which encompasses the basic-helix-loop-helix and PAS A/B domains, but lacks a transactivation domain at its carboxyl end. Herein, we report another truncated ARNT2-like factor, ARNT2X, in zebrafish, which differs from ARNT2A at its N-terminal region. In cultured ZLE cells, transiently expressed ARNT2X and ARNT2A inhibited 2,3,7,8-TCDD-activated cyp1a1 transcription with different efficiencies. In the developing embryo, arnt2X mRNA was consistently expressed in the retinal and neural tube regions until the hatching stages, but it exhibited a more specific pattern at larval stages, including expression in the brain, eyes, hypothalamus, pharyngeal skeleton, heart, liver, pronephros duct, pectoral fin, and epithelial cells of the swim bladder. In contrast, arnt2A transcription diminished after hatching. Microinjecting a recombinant arnt2X-expression vector into fertilized eggs before cleavage stages caused severe defects in brain, eyes, pectoral fin, heart, and gut development. This suggests that the ARNT-mediated signal transduction pathways play important roles in fish tissue development.
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Affiliation(s)
- H J Hsu
- Institute of Marine Biotechnology, National Taiwan Ocean University, 2, Pei-Ning Road, Keelung, Taiwan, 202-24, Republic of China
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33
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Bunger MK, Wilsbacher LD, Moran SM, Clendenin C, Radcliffe LA, Hogenesch JB, Simon MC, Takahashi JS, Bradfield CA. Mop3 is an essential component of the master circadian pacemaker in mammals. Cell 2000; 103:1009-17. [PMID: 11163178 PMCID: PMC3779439 DOI: 10.1016/s0092-8674(00)00205-1] [Citation(s) in RCA: 1194] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Circadian oscillations in mammalian physiology and behavior are regulated by an endogenous biological clock. Here we show that loss of the PAS protein MOP3 (also known as BMAL1) in mice results in immediate and complete loss of circadian rhythmicity in constant darkness. Additionally, locomotor activity in light-dark (LD) cycles is impaired and activity levels are reduced in Mop3-/- mice. Analysis of Period gene expression in the suprachiasmatic nucleus (SCN) indicates that these behavioral phenotypes arise from loss of circadian function at the molecular level. These results provide genetic evidence that MOP3 is the bona fide heterodimeric partner of mCLOCK. Furthermore, these data demonstrate that MOP3 is a nonredundant and essential component of the circadian pacemaker in mammals.
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Affiliation(s)
- Maureen K. Bunger
- The McArdle Laboratory for Cancer Research University of Wisconsin Medical School Madison, Wisconsin 53706
| | - Lisa D. Wilsbacher
- Howard Hughes Medical Institute Department of Neurobiology and Physiology Northwestern University Evanston, Illinois 60208
| | - Susan M. Moran
- The McArdle Laboratory for Cancer Research University of Wisconsin Medical School Madison, Wisconsin 53706
| | - Cynthia Clendenin
- Howard Hughes Medical Institute Departments of Medicine and Molecular Genetics and Cell Biology University of Chicago Chicago, Illinois 60637
| | - Laurel A. Radcliffe
- Howard Hughes Medical Institute Department of Neurobiology and Physiology Northwestern University Evanston, Illinois 60208
| | - John B. Hogenesch
- The McArdle Laboratory for Cancer Research University of Wisconsin Medical School Madison, Wisconsin 53706
| | - M. Celeste Simon
- Howard Hughes Medical Institute Departments of Medicine and Molecular Genetics and Cell Biology University of Chicago Chicago, Illinois 60637
| | - Joseph S. Takahashi
- Howard Hughes Medical Institute Department of Neurobiology and Physiology Northwestern University Evanston, Illinois 60208
| | - Christopher A. Bradfield
- The McArdle Laboratory for Cancer Research University of Wisconsin Medical School Madison, Wisconsin 53706
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Ikeda M, Yu W, Hirai M, Ebisawa T, Honma S, Yoshimura K, Honma KI, Nomura M. cDNA cloning of a novel bHLH-PAS transcription factor superfamily gene, BMAL2: its mRNA expression, subcellular distribution, and chromosomal localization. Biochem Biophys Res Commun 2000; 275:493-502. [PMID: 10964693 DOI: 10.1006/bbrc.2000.3248] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We isolated a human cDNA encoding a novel member of the bHLH-PAS transcription factor superfamily, BMAL2, which is highly similar to, but distinct from, BMAL1. The composite cDNA covered a 1720-bp sequence consisting of a putative 1653-bp open reading frame encoding a polypeptide of 551 amino acids. The deduced BMAL2 product contains a bHLH-PAS domain in its N-terminal region and a variable C-terminus. The overall identity of BMAL2 polypeptide to that of human BMAL1 is 49%. RNA analysis revealed that expression of BMAL2 transcripts was restricted to the fetal brain and to the adult liver in human, while human BMAL1 mRNA was expressed in the brain and skeletal muscle. The chromosomal localization of the human BMAL2 gene was determined by fluorescent in situ hybridization to be localized on chromosome 12 at region p12.2-p11.2. These results suggest that BMAL2 may play different roles from BMAL1 in the embryonic brain and in adult mammals.
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Affiliation(s)
- M Ikeda
- Department of Physiology, Saitama Medical School, Moroyama, Saitama, 350-0495, Japan.
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Shearman LP, Sriram S, Weaver DR, Maywood ES, Chaves I, Zheng B, Kume K, Lee CC, van der Horst GT, Hastings MH, Reppert SM. Interacting molecular loops in the mammalian circadian clock. Science 2000; 288:1013-9. [PMID: 10807566 DOI: 10.1126/science.288.5468.1013] [Citation(s) in RCA: 1015] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We show that, in the mouse, the core mechanism for the master circadian clock consists of interacting positive and negative transcription and translation feedback loops. Analysis of Clock/Clock mutant mice, homozygous Period2(Brdm1) mutants, and Cryptochrome-deficient mice reveals substantially altered Bmal1 rhythms, consistent with a dominant role of PERIOD2 in the positive regulation of the Bmal1 loop. In vitro analysis of CRYPTOCHROME inhibition of CLOCK: BMAL1-mediated transcription shows that the inhibition is through direct protein:protein interactions, independent of the PERIOD and TIMELESS proteins. PERIOD2 is a positive regulator of the Bmal1 loop, and CRYPTOCHROMES are the negative regulators of the Period and Cryptochrome cycles.
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Affiliation(s)
- L P Shearman
- Laboratory of Developmental Chronobiology, MassGeneral Hospital for Children, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
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