1
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Ono D, Weaver DR, Hastings MH, Honma KI, Honma S, Silver R. The Suprachiasmatic Nucleus at 50: Looking Back, Then Looking Forward. J Biol Rhythms 2024; 39:135-165. [PMID: 38366616 PMCID: PMC7615910 DOI: 10.1177/07487304231225706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2024]
Abstract
It has been 50 years since the suprachiasmatic nucleus (SCN) was first identified as the central circadian clock and 25 years since the last overview of developments in the field was published in the Journal of Biological Rhythms. Here, we explore new mechanisms and concepts that have emerged in the subsequent 25 years. Since 1997, methodological developments, such as luminescent and fluorescent reporter techniques, have revealed intricate relationships between cellular and network-level mechanisms. In particular, specific neuropeptides such as arginine vasopressin, vasoactive intestinal peptide, and gastrin-releasing peptide have been identified as key players in the synchronization of cellular circadian rhythms within the SCN. The discovery of multiple oscillators governing behavioral and physiological rhythms has significantly advanced our understanding of the circadian clock. The interaction between neurons and glial cells has been found to play a crucial role in regulating these circadian rhythms within the SCN. Furthermore, the properties of the SCN network vary across ontogenetic stages. The application of cell type-specific genetic manipulations has revealed components of the functional input-output system of the SCN and their correlation with physiological functions. This review concludes with the high-risk effort of identifying open questions and challenges that lie ahead.
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Affiliation(s)
- Daisuke Ono
- Stress Recognition and Response, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Neural Regulation, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - David R Weaver
- Department of Neurobiology and NeuroNexus Institute, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Michael H Hastings
- Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Ken-Ichi Honma
- Research and Education Center for Brain Science, Hokkaido University, Sapporo, Japan
- Center for Sleep and Circadian Rhythm Disorders, Sapporo Hanazono Hospital, Sapporo, Japan
| | - Sato Honma
- Research and Education Center for Brain Science, Hokkaido University, Sapporo, Japan
- Center for Sleep and Circadian Rhythm Disorders, Sapporo Hanazono Hospital, Sapporo, Japan
| | - Rae Silver
- Stress Recognition and Response, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Neural Regulation, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Department of Neuroscience & Behavior, Barnard College and Department of Psychology, Columbia University, New York City, New York, USA
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2
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Jo A, Deniz S, Xu J, Duvoisin RM, DeVries SH, Zhu Y. A sign-inverted receptive field of inhibitory interneurons provides a pathway for ON-OFF interactions in the retina. Nat Commun 2023; 14:5937. [PMID: 37741839 PMCID: PMC10517963 DOI: 10.1038/s41467-023-41638-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 09/11/2023] [Indexed: 09/25/2023] Open
Abstract
A fundamental organizing plan of the retina is that visual information is divided into ON and OFF streams that are processed in separate layers. This functional dichotomy originates in the ON and OFF bipolar cells, which then make excitatory glutamatergic synapses onto amacrine and ganglion cells in the inner plexiform layer. We have identified an amacrine cell (AC), the sign-inverting (SI) AC, that challenges this fundamental plan. The glycinergic, ON-stratifying SI-AC has OFF light responses. In opposition to the classical wiring diagrams, it receives inhibitory inputs from glutamatergic ON bipolar cells at mGluR8 synapses, and excitatory inputs from an OFF wide-field AC at electrical synapses. This "inhibitory ON center - excitatory OFF surround" receptive-field of the SI-AC allows it to use monostratified dendrites to conduct crossover inhibition and push-pull activation to enhance light detection by ACs and RGCs in the dark and feature discrimination in the light.
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Affiliation(s)
- Andrew Jo
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Sercan Deniz
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Jian Xu
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Robert M Duvoisin
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Steven H DeVries
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
| | - Yongling Zhu
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
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3
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Schirmer AE, Kumar V, Schook A, Song EJ, Marshall MS, Takahashi JS. Cry1 expression during postnatal development is critical for the establishment of normal circadian period. Front Neurosci 2023; 17:1166137. [PMID: 37389366 PMCID: PMC10300422 DOI: 10.3389/fnins.2023.1166137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 05/23/2023] [Indexed: 07/01/2023] Open
Abstract
The mammalian circadian system generates an approximate 24-h rhythm through a complex autoregulatory feedback loop. Four genes, Period1 (Per1), Period2 (Per2), Cryptochrome1 (Cry1), and Cryptochrome2 (Cry2), regulate the negative feedback within this loop. Although these proteins have distinct roles within the core circadian mechanism, their individual functions are poorly understood. Here, we used a tetracycline trans-activator system (tTA) to examine the role of transcriptional oscillations in Cry1 and Cry2 in the persistence of circadian activity rhythms. We demonstrate that rhythmic Cry1 expression is an important regulator of circadian period. We then define a critical period from birth to postnatal day 45 (PN45) where the level of Cry1 expression is critical for setting the endogenous free running period in the adult animal. Moreover, we show that, although rhythmic Cry1 expression is important, in animals with disrupted circadian rhythms overexpression of Cry1 is sufficient to restore normal behavioral periodicity. These findings provide new insights into the roles of the Cryptochrome proteins in circadian rhythmicity and further our understanding of the mammalian circadian clock.
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Affiliation(s)
- Aaron E. Schirmer
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
- Department of Biology, Northeastern Illinois University, Chicago, IL, United States
| | - Vivek Kumar
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
- The Jackson Laboratory, Bar Harbor, ME, United States
| | - Andrew Schook
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
| | - Eun Joo Song
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
| | - Michael S. Marshall
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
- Department of Pathology, Massachusetts General Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
| | - Joseph S. Takahashi
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
- Department of Neuroscience, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States
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4
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Yang LN, Xu S, Tang M, Zhou X, Liao Y, Nüssler AK, Liu L, Yang W. The circadian rhythm gene Bmal1 ameliorates acute deoxynivalenol-induced liver damage. Arch Toxicol 2023; 97:787-804. [PMID: 36602574 DOI: 10.1007/s00204-022-03431-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 12/13/2022] [Indexed: 01/06/2023]
Abstract
Deoxynivalenol (DON) is widely emerging in various grain crops, milk, and wine products, which can trigger different toxic effects on humans and animals by inhalation or ingestion. It also imposes a considerable financial loss on the agriculture and food industry each year. Previous studies have reported acute and chronic toxicity of DON in liver, and liver is not only the main detoxification organ for DON but also the circadian clock oscillator directly or indirectly regulates critical physiologically hepatic functions under different physiological and pathological conditions. However, researches on the association of circadian rhythm in DON-induced liver damage are limited. In the present study, mice were divided into four groups (CON, DON, Bmal1OE, and Bmal1OE + DON) and AAV8 was used to activate (Bmal1) expression in liver. Then mice were gavaged with 5 mg/kg bw/day DON or saline at different time points (ZT24 = 0, 4, 8, 12, 16, and 20 h) in 1 day and were sacrificed 30 min after oral gavage. The inflammatory cytokines, signal transducers, and activators of transcription Janus kinase/signal transducers and activator of transcription 3 (JAKs/STAT3) pathway and bile acids levels were detected by enzyme-linked immunosorbent assay (ELISA), western blotting, and target metabolomics, respectively. The DON group showed significantly elevated interleukin-1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α) levels (P < 0.05 for both) and impaired liver function with rhythm disturbances compared to the CON and Bmal1OE groups. At the molecular level, expressions of some circadian clock proteins were significantly downregulated (P < 0.05 for both) and JAKs/STAT3 pathway was activated during DON exposure, accompanied by indicated circadian rhythm disturbance and inflammatory damage. Importantly, Bmal1 overexpression attenuated DON-induced liver damage, while related hepatic bile acids such as cholic acid (CA) showed a decreasing trend in the DON group compared with the CON group. Our study demonstrates a novel finding that Bmal1 plays a critical role in attenuating liver damage by inhibiting inflammatory levels and maintaining bile acids levels under the DON condition. Therefore, Bmal1 may also be a potential molecular target for reducing the hepatotoxic effects of DON in future studies.
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Affiliation(s)
- Liu-Nan Yang
- Department of Nutrition and Food Hygiene, Hubei Key Laboratory of Food Nutrition and Safety, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
- Department of Nutrition and Food Hygiene and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
| | - Shiyin Xu
- Department of Nutrition and Food Hygiene, Hubei Key Laboratory of Food Nutrition and Safety, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
- Department of Nutrition and Food Hygiene and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
| | - Mingmeng Tang
- Department of Nutrition and Food Hygiene, Hubei Key Laboratory of Food Nutrition and Safety, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
- Department of Nutrition and Food Hygiene and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
| | - Xiaolei Zhou
- Department of Nutrition and Food Hygiene, Hubei Key Laboratory of Food Nutrition and Safety, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
- Department of Nutrition and Food Hygiene and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
| | - Yuxiao Liao
- Department of Nutrition and Food Hygiene, Hubei Key Laboratory of Food Nutrition and Safety, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
- Department of Nutrition and Food Hygiene and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
| | - Andreas K Nüssler
- Department of Traumatology, BG Trauma Center, University of Tübingen, Schnarrenbergstr. 95, 72076, Tübingen, Germany
| | - Liegang Liu
- Department of Nutrition and Food Hygiene, Hubei Key Laboratory of Food Nutrition and Safety, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
- Department of Nutrition and Food Hygiene and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China
| | - Wei Yang
- Department of Nutrition and Food Hygiene, Hubei Key Laboratory of Food Nutrition and Safety, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China.
- Department of Nutrition and Food Hygiene and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, China.
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5
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Dannerfjord AA, Brown LA, Foster RG, Peirson SN. Light Input to the Mammalian Circadian Clock. Methods Mol Biol 2021; 2130:233-247. [PMID: 33284449 DOI: 10.1007/978-1-0716-0381-9_18] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Circadian rhythms are 24-h cycles in physiology and behavior that occur in virtually all organisms. These processes are not simply driven by changes in the external environment as they persist under constant conditions, providing evidence for an internal biological clock. In mammals, this clock is located in the hypothalamic suprachiasmatic nuclei (SCN) and is based upon an intracellular mechanism composed of a transcriptional-translational feedback loop composed of a number of core clock genes. However, a clock is of no use unless it can be set to the correct time. The primary time cue for the molecular clock in the SCN is light detected by the eye. The photoreceptors involved in this process include the rods and cones that mediate vision, as well as the recently identified melanopsin-expressing photosensitive retinal ganglion cells (pRGCs). Light information is conveyed to the SCN via the retinohypothalamic tract, resulting in an intracellular signaling cascade which converges on cAMP-response elements in the promoters of several key clock genes. Over the last two decades a number of studies have investigated the transcriptional response of the SCN to light stimuli with the aim of further understanding these molecular signaling pathways. Here we provide an overview of these studies and provide protocols for studying the molecular responses to light in the SCN clock.
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Affiliation(s)
- Adam A Dannerfjord
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.,Nuffield Department of Clinical Neurosciences, Sleep and Circadian Neuroscience Institute (SCNi), Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, Oxford, UK
| | - Laurence A Brown
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Russell G Foster
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.,Nuffield Department of Clinical Neurosciences, Sleep and Circadian Neuroscience Institute (SCNi), Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, Oxford, UK
| | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK. .,Nuffield Department of Clinical Neurosciences, Sleep and Circadian Neuroscience Institute (SCNi), Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, Oxford, UK.
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6
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Le PT, Bornstein SA, Motyl KJ, Tian L, Stubblefield JJ, Hong HK, Takahashi JS, Green CB, Rosen CJ, Guntur AR. A novel mouse model overexpressing Nocturnin results in decreased fat mass in male mice. J Cell Physiol 2019; 234:20228-20239. [PMID: 30953371 DOI: 10.1002/jcp.28623] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/09/2019] [Accepted: 03/19/2019] [Indexed: 12/13/2022]
Abstract
Nocturnin (NOCT) belongs to the Mg2+ dependent Exonucleases, Endonucleases, Phosphatase (EEP) family of enzymes that exhibit various functions in vitro and in vivo. NOCT is known to function as a deadenylase, cleaving poly-A tails from mRNA (messenger RNA) transcripts. Previously, we reported a role for NOCT in regulating bone marrow stromal cell differentiation through its interactions with PPARγ. In this study, we characterized the skeletal and adipose tissue phenotype when we globally overexpressed Noct in vivo. After 12 weeks of Noct overexpression, transgenic male mice had lower fat mass compared to controls, with no significant differences in the skeleton. Based on the presence of a mitochondrial target sequence in NOCT, we determined that mouse NOCT protein localizes to the mitochondria; subsequently, we found that NOCT overexpression led to a significant increase in the preadipocytes ability to utilize oxidative phosphorylation for ATP (adenosine triphosphate) generation. In summary, the effects of NOCT on adipocytes are likely through its novel role as a mediator of mitochondrial function.
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Affiliation(s)
- Phuong T Le
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine
| | - Sheila A Bornstein
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine
| | - Katherine J Motyl
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
| | - Li Tian
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
| | - Jeremy J Stubblefield
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Hee-Kyung Hong
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Joseph S Takahashi
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Carla B Green
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Clifford J Rosen
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine.,Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
| | - Anyonya R Guntur
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine.,Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
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7
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Haenseler W, Rajendran L. Concise Review: Modeling Neurodegenerative Diseases with Human Pluripotent Stem Cell-Derived Microglia. Stem Cells 2019; 37:724-730. [PMID: 30801863 PMCID: PMC6849818 DOI: 10.1002/stem.2995] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/25/2019] [Accepted: 02/03/2019] [Indexed: 12/11/2022]
Abstract
Inflammation of the brain and the consequential immunological responses play pivotal roles in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and frontotemporal dementia (FTD). Microglia, the resident macrophage cells of the brain, have also emerged as key players in neuroinflammation. As primary human microglia from living subjects are normally not accessible to researchers, there is a pressing need for an alternative source of authentic human microglia which allows modeling of neurodegeneration in vitro. Several protocols for induced pluripotent stem cell (iPSC)‐derived microglia have recently been developed and provide unlimited access to patient‐derived material. In this present study, we give an overview of iPSC‐derived microglia models in monoculture and coculture systems, their advantages and limitations, and how they have already been used for disease phenotyping. Furthermore, we outline some of the gene engineering tools to generate isogenic controls, the creation of gene knockout iPSC lines, as well as covering reporter cell lines, which could help to elucidate complex cell interaction mechanisms in the microglia/neuron coculture system, for example, microglia‐induced synapse loss. Finally, we deliberate on how said cocultures could aid in personalized drug screening to identify patient‐specific therapies against neurodegeneration. stem cells2019;37:724–730
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Affiliation(s)
- Walther Haenseler
- Systems and Cell Biology of Neurodegeneration, IREM, University of Zurich, Schlieren, Switzerland
| | - Lawrence Rajendran
- Systems and Cell Biology of Neurodegeneration, IREM, University of Zurich, Schlieren, Switzerland.,UK-Dementia Research Institute (UK-DRI), Maurice Wohl Basic & Clinical Neuroscience Institute, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, United Kingdom
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8
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Maywood ES. Synchronization and maintenance of circadian timing in the mammalian clockwork. Eur J Neurosci 2018; 51:229-240. [DOI: 10.1111/ejn.14279] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 10/19/2018] [Accepted: 10/30/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Elizabeth S. Maywood
- Neurobiology DivisionMedical Research Council Laboratory of Molecular Biology Cambridge UK
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9
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Translational switching of Cry1 protein expression confers reversible control of circadian behavior in arrhythmic Cry-deficient mice. Proc Natl Acad Sci U S A 2018; 115:E12388-E12397. [PMID: 30487216 PMCID: PMC6310849 DOI: 10.1073/pnas.1811438115] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Circadian rhythms dominate our lives through our daily cycle of sleep and wakefulness. They are controlled by a brain master clock: the suprachiasmatic nucleus (SCN). SCN timekeeping pivots around a molecular loop incorporating Cryptochrome (Cry) proteins; global loss of these proteins disables the clock. We developed a biologically appropriate translational switch based on genetic code expansion to achieve reversible control of Cry1 expression. Cry1 translation in neurons of arrhythmic Cry-null SCN slices immediately, reversibly, and dose-dependently initiated circadian molecular rhythms. Cry1 translation in SCN neurons was sufficient to initiate circadian behavior rapidly and reversibly in arrhythmic Cry-null mice. This demonstrates control of mammalian behavior using translational switching, a method of broad applicability. The suprachiasmatic nucleus (SCN) is the principal circadian clock of mammals, coordinating daily rhythms of physiology and behavior. Circadian timing pivots around self-sustaining transcriptional–translational negative feedback loops (TTFLs), whereby CLOCK and BMAL1 drive the expression of the negative regulators Period and Cryptochrome (Cry). Global deletion of Cry1 and Cry2 disables the TTFL, resulting in arrhythmicity in downstream behaviors. We used this highly tractable biology to further develop genetic code expansion (GCE) as a translational switch to achieve reversible control of a biologically relevant protein, Cry1, in the SCN. This employed an orthogonal aminoacyl-tRNA synthetase/tRNACUA pair delivered to the SCN by adeno-associated virus (AAV) vectors, allowing incorporation of a noncanonical amino acid (ncAA) into AAV-encoded Cry1 protein carrying an ectopic amber stop codon. Thus, translational readthrough and Cry1 expression were conditional on the supply of ncAA via culture medium or drinking water and were restricted to neurons by synapsin-dependent expression of aminoacyl tRNA-synthetase. Activation of Cry1 translation by ncAA in neurons of arrhythmic Cry-null SCN slices immediately and dose-dependently initiated TTFL circadian rhythms, which dissipated rapidly after ncAA withdrawal. Moreover, genetic activation of the TTFL in SCN neurons rapidly and reversibly initiated circadian behavior in otherwise arrhythmic Cry-null mice, with rhythm amplitude being determined by the number of transduced SCN neurons. Thus, Cry1 does not specify the development of circadian circuitry and competence but is essential for its labile and rapidly reversible activation. This demonstrates reversible control of mammalian behavior using GCE-based translational switching, a method of potentially broad neurobiological interest.
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10
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Atkins N, Ren S, Hatcher N, Burgoon PW, Mitchell JW, Sweedler JV, Gillette MU. Functional Peptidomics: Stimulus- and Time-of-Day-Specific Peptide Release in the Mammalian Circadian Clock. ACS Chem Neurosci 2018; 9:2001-2008. [PMID: 29901982 DOI: 10.1021/acschemneuro.8b00089] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Daily oscillations of brain and body states are under complex temporal modulation by environmental light and the hypothalamic suprachiasmatic nucleus (SCN), the master circadian clock. To better understand mediators of differential temporal modulation, we characterize neuropeptide releasate profiles by nonselective capture of secreted neuropeptides in an optic nerve horizontal SCN brain slice model. Releasates are collected following electrophysiological stimulation of the optic nerve/retinohypothalamic tract under conditions that alter the phase of the SCN activity state. Secreted neuropeptides are identified by intact mass via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). We found time-of-day-specific suites of peptides released downstream of optic nerve stimulation. Peptide release was modified differentially with respect to time-of-day by stimulus parameters and by inhibitors of glutamatergic or PACAPergic neurotransmission. The results suggest that SCN physiology is modulated by differential peptide release of both known and unexpected peptides that communicate time-of-day-specific photic signals via previously unreported neuropeptide signatures.
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11
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Black SW, Sun JD, Santiago P, Laihsu A, Kimura N, Yamanaka A, Bersot R, Humphries PS. Partial ablation of the orexin field induces a sub-narcoleptic phenotype in a conditional mouse model of orexin neurodegeneration. Sleep 2018; 41:5025920. [DOI: 10.1093/sleep/zsy116] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 05/29/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- Sarah Wurts Black
- In Vivo Biology Department, Reset Therapeutics, South San Francisco, CA
| | - Jessica D Sun
- In Vivo Biology Department, Reset Therapeutics, South San Francisco, CA
| | - Pamela Santiago
- In Vivo Biology Department, Reset Therapeutics, South San Francisco, CA
| | - Alex Laihsu
- In Vivo Biology Department, Reset Therapeutics, South San Francisco, CA
| | - Nikki Kimura
- In Vivo Biology Department, Reset Therapeutics, South San Francisco, CA
| | - Akihiro Yamanaka
- Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Ross Bersot
- In Vivo Biology Department, Reset Therapeutics, South San Francisco, CA
| | - Paul S Humphries
- In Vivo Biology Department, Reset Therapeutics, South San Francisco, CA
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12
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Brown LA, Peirson SN. Improving Reproducibility and Candidate Selection in Transcriptomics Using Meta-analysis. J Exp Neurosci 2018; 12:1179069518756296. [PMID: 29511359 PMCID: PMC5833209 DOI: 10.1177/1179069518756296] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 01/08/2018] [Indexed: 11/15/2022] Open
Abstract
Transcriptomic experiments are often used in neuroscience to identify candidate genes of interest for further study. However, the lists of genes identified from comparable transcriptomic studies often show limited overlap. One approach to addressing this issue of reproducibility is to combine data from multiple studies in the form of a meta-analysis. Here, we discuss recent work in the field of circadian biology, where transcriptomic meta-analyses have been used to improve candidate gene selection. With the increasing availability of microarray and RNA-Seq data due to deposition in public databases, combined with freely available tools and code, transcriptomic meta-analysis provides an ideal example of how open data can benefit neuroscience research.
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Affiliation(s)
- Laurence A Brown
- Sleep and Circadian Neuroscience Institute (SCNi),
Nuffield Department of Clinical Neurosciences, Sir William Dunn School of
Pathology, University of Oxford, Oxford, UK
| | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute (SCNi),
Nuffield Department of Clinical Neurosciences, Sir William Dunn School of
Pathology, University of Oxford, Oxford, UK
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13
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Ehlen JC, Brager AJ, Baggs J, Pinckney L, Gray CL, DeBruyne JP, Esser KA, Takahashi JS, Paul KN. Bmal1 function in skeletal muscle regulates sleep. eLife 2017; 6:e26557. [PMID: 28726633 PMCID: PMC5574702 DOI: 10.7554/elife.26557] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 07/12/2017] [Indexed: 01/08/2023] Open
Abstract
Sleep loss can severely impair the ability to perform, yet the ability to recover from sleep loss is not well understood. Sleep regulatory processes are assumed to lie exclusively within the brain mainly due to the strong behavioral manifestations of sleep. Whole-body knockout of the circadian clock gene Bmal1 in mice affects several aspects of sleep, however, the cells/tissues responsible are unknown. We found that restoring Bmal1 expression in the brains of Bmal1-knockout mice did not rescue Bmal1-dependent sleep phenotypes. Surprisingly, most sleep-amount, but not sleep-timing, phenotypes could be reproduced or rescued by knocking out or restoring BMAL1 exclusively in skeletal muscle, respectively. We also found that overexpression of skeletal-muscle Bmal1 reduced the recovery response to sleep loss. Together, these findings demonstrate that Bmal1 expression in skeletal muscle is both necessary and sufficient to regulate total sleep amount and reveal that critical components of normal sleep regulation occur in muscle.
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Affiliation(s)
- J Christopher Ehlen
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, United States
| | - Allison J Brager
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, United States
- Behavioral Biology Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, United States
| | - Julie Baggs
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, United States
| | - Lennisha Pinckney
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, United States
| | - Cloe L Gray
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, United States
| | - Jason P DeBruyne
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, United States
| | - Karyn A Esser
- Myology Institute, College of Medicine, University of Florida, Gainesville, United States
| | - Joseph S Takahashi
- Department of Neuroscience, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Ketema N Paul
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, United States
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California, United States
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14
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Tso CF, Simon T, Greenlaw AC, Puri T, Mieda M, Herzog ED. Astrocytes Regulate Daily Rhythms in the Suprachiasmatic Nucleus and Behavior. Curr Biol 2017; 27:1055-1061. [PMID: 28343966 DOI: 10.1016/j.cub.2017.02.037] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 02/09/2017] [Accepted: 02/15/2017] [Indexed: 12/30/2022]
Abstract
Astrocytes are active partners in neural information processing [1, 2]. However, the roles of astrocytes in regulating behavior remain unclear [3, 4]. Because astrocytes have persistent circadian clock gene expression and ATP release in vitro [5-8], we hypothesized that they regulate daily rhythms in neurons and behavior. Here, we demonstrated that daily rhythms in astrocytes within the mammalian master circadian pacemaker, the suprachiasmatic nucleus (SCN), determine the period of wheel-running activity. Ablating the essential clock gene Bmal1 specifically in SCN astrocytes lengthened the circadian period of clock gene expression in the SCN and in locomotor behavior. Similarly, excision of the short-period CK1ε tau mutation specifically from SCN astrocytes resulted in lengthened rhythms in the SCN and behavior. These results indicate that astrocytes within the SCN communicate to neurons to determine circadian rhythms in physiology and in rest activity.
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Affiliation(s)
- Chak Foon Tso
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63108, USA
| | - Tatiana Simon
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63108, USA
| | - Alison C Greenlaw
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63108, USA
| | - Tanvi Puri
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63108, USA
| | - Michihiro Mieda
- Department of Molecular Neuroscience and Integrative Physiology, Kanazawa University, 920-1192 Ishikawa, Japan
| | - Erik D Herzog
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63108, USA.
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15
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Tsang AH, Astiz M, Leinweber B, Oster H. Rodent Models for the Analysis of Tissue Clock Function in Metabolic Rhythms Research. Front Endocrinol (Lausanne) 2017; 8:27. [PMID: 28243224 PMCID: PMC5304405 DOI: 10.3389/fendo.2017.00027] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 01/30/2017] [Indexed: 11/30/2022] Open
Abstract
The circadian timing system consists on a distributed network of cellular clocks that together coordinate 24-h rhythms of physiology and behavior. Clock function and metabolism are tightly coupled, from the cellular to the organismal level. Genetic and non-genetic approaches in rodents have been employed to study circadian clock function in the living organism. Due to the ubiquitous expression of clock genes and the intricate interaction between the circadian system and energy metabolism, genetic approaches targeting specific tissue clocks have been used to assess their contribution in systemic metabolic processes. However, special requirements regarding specificity and efficiency have to be met to allow for valid conclusions from such studies. In this review, we provide a brief summary of different approaches developed for dissecting tissue clock function in the metabolic context in rodents, compare their strengths and weaknesses, and suggest new strategies in assessing tissue clock output and the consequences of circadian clock disruption in vivo.
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Affiliation(s)
- Anthony H. Tsang
- Chronophysiology Group, Medical Department I, University of Lübeck, Lübeck, Germany
- Department of Clinical Biochemistry, Institute of Metabolic Science, University of Cambridge, Cambridge, UK
| | - Mariana Astiz
- Chronophysiology Group, Medical Department I, University of Lübeck, Lübeck, Germany
| | - Brinja Leinweber
- Chronophysiology Group, Medical Department I, University of Lübeck, Lübeck, Germany
| | - Henrik Oster
- Chronophysiology Group, Medical Department I, University of Lübeck, Lübeck, Germany
- *Correspondence: Henrik Oster,
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16
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Huang G, Zhang Y, Shan Y, Yang S, Chelliah Y, Wang H, Takahashi JS. Circadian Oscillations of NADH Redox State Using a Heterologous Metabolic Sensor in Mammalian Cells. J Biol Chem 2016; 291:23906-23914. [PMID: 27645993 DOI: 10.1074/jbc.m116.728774] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 07/18/2016] [Indexed: 12/13/2022] Open
Abstract
It is known that there are mechanistic links between circadian clocks and metabolic cycles. Reduced nicotinamide adenine dinucleotide (NADH) is a key metabolic cofactor in all living cells; however, it is not known whether levels of NADH oscillate or not. Here we employed REX, a bacterial NADH-binding protein, fused to the VP16 activator to convert intracellular endogenous redox balance into transcriptional readouts by a reporter gene in mammalian cells. EMSA results show that the DNA binding activity of both T- and S-REX::VP16 fusions is decreased with a reduced-to-oxidized cofactor ratio increase. Transient and stabilized cell lines bearing the REX::VP16 and the REX binding operator (ROP) exhibit two circadian luminescence cycles. Consistent with these results, NADH oscillations are observed in host cells, indicating REX can act as a NADH sensor to report intracellular dynamic redox homeostasis in mammalian cells in real time. NADH oscillations provide another metabolic signal for coupling the circadian clock and cellular metabolic states.
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Affiliation(s)
- Guocun Huang
- From the Department of Neuroscience and .,Center for Circadian Clocks, Soochow University, Suzhou 215123, China
| | - Yunfeng Zhang
- Center for Circadian Clocks, Soochow University, Suzhou 215123, China
| | | | - Shuzhang Yang
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
| | - Yogarany Chelliah
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
| | - Han Wang
- Center for Circadian Clocks, Soochow University, Suzhou 215123, China
| | - Joseph S Takahashi
- From the Department of Neuroscience and .,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
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17
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Shimada H, Otero M, Tsuchimochi K, Yamasaki S, Sakakima H, Matsuda F, Sakasegawa M, Setoguchi T, Xu L, Goldring MB, Tanimoto A, Komiya S, Ijiri K. CCAAT/enhancer binding protein β (C/EBPβ) regulates the transcription of growth arrest and DNA damage-inducible protein 45 β (GADD45β) in articular chondrocytes. Pathol Res Pract 2016; 212:302-9. [PMID: 26896926 DOI: 10.1016/j.prp.2016.01.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 01/09/2016] [Accepted: 01/24/2016] [Indexed: 01/29/2023]
Abstract
Osteoarthritis (OA) is a whole joint disease characterized by cartilage degradation, which causes pain and disability in older adults. Our previous work showed that growth arrest and DNA damage-inducible protein 45 β (GADD45β) is upregulated in chondrocyte clusters in OA cartilage, especially in the early stage of this disease. CCAAT/enhancer binding protein β (C/EBPβ) is expressed in the hypertrophic growth plate chondrocytes and functions in synergy with GADD45β. Here, the presence and localization of these proteins was assessed by immunohistochemistry using articular cartilage from OA patients, revealing colocalization of C/EBPβ and GADD45β in OA chondrocytes. GADD45β promoter analysis was performed to determine whether C/EBPβ directly regulates GADD45β transcription. Furthermore, we analyzed the effect of C/EBPβ on Gadd45β gene regulation in articular chondrocytes in vivo and in vitro. Immunohistochemical analysis of C/ebpβ-haploinsufficient mice (C/ebpβ(+/-)) cartilage showed that C/ebpβ haploinsufficiency led to reduced Gadd45β gene expression in these cells. In vitro, we evaluated the effects of conditional C/EBPβ overexpression driven by the cartilage oligomeric matrix protein (Comp) promoter in mComp-tTA;pTRE-Tight-BI-DsRed-mC/ebpβ transgenic mice. C/EBPβ overexpression significantly stimulated Gadd45β gene expression in articular chondrocytes. Taken together, our data demonstrate that C/EBPβ plays a central role in controlling Gadd45β gene expression in these cells.
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Affiliation(s)
- Hirofumi Shimada
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
| | - Miguel Otero
- Laboratory for Cartilage Biology, Research Division, Hospital for Special Surgery, Weill Cornell Medical College, New York, NY, USA
| | - Kaneyuki Tsuchimochi
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan; Onga Nakama Medical Association, Onga Hospital, Fukuoka, Japan
| | - Satoshi Yamasaki
- Department of Clinical Immunology and Rheumatology, Hiroshima University, Hiroshima, Japan
| | - Harutoshi Sakakima
- Course of Physical Therapy, School of Health Sciences, Faculty of Medicine, Kagoshima University, Kagoshima, Japan
| | - Fumiyo Matsuda
- Course of Physical Therapy, School of Health Sciences, Faculty of Medicine, Kagoshima University, Kagoshima, Japan
| | - Megumi Sakasegawa
- Course of Physical Therapy, School of Health Sciences, Faculty of Medicine, Kagoshima University, Kagoshima, Japan
| | - Takao Setoguchi
- The Near-Future Locomotor Organ Medicine Creation Course (Kusunoki Kai), Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Lin Xu
- Department of Developmental Biology, Harvard School of Dental Medicine And Faculty of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Mary B Goldring
- Laboratory for Cartilage Biology, Research Division, Hospital for Special Surgery, Weill Cornell Medical College, New York, NY, USA
| | - Akihide Tanimoto
- Department of Human Pathology, Field of Oncology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Setsuro Komiya
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Kosei Ijiri
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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18
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Takahashi JS. Molecular Architecture of the Circadian Clock in Mammals. RESEARCH AND PERSPECTIVES IN ENDOCRINE INTERACTIONS 2016. [DOI: 10.1007/978-3-319-27069-2_2] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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19
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Sinha P, Aarnisalo P, Chubb R, Poulton IJ, Guo J, Nachtrab G, Kimura T, Swami S, Saeed H, Chen M, Weinstein LS, Schipani E, Sims NA, Kronenberg HM, Wu JY. Loss of Gsα in the Postnatal Skeleton Leads to Low Bone Mass and a Blunted Response to Anabolic Parathyroid Hormone Therapy. J Biol Chem 2015; 291:1631-1642. [PMID: 26598522 DOI: 10.1074/jbc.m115.679753] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Indexed: 12/25/2022] Open
Abstract
Parathyroid hormone (PTH) is an important regulator of osteoblast function and is the only anabolic therapy currently approved for treatment of osteoporosis. The PTH receptor (PTH1R) is a G protein-coupled receptor that signals via multiple G proteins including Gsα. Mice expressing a constitutively active mutant PTH1R exhibited a dramatic increase in trabecular bone that was dependent upon expression of Gsα in the osteoblast lineage. Postnatal removal of Gsα in the osteoblast lineage (P-Gsα(OsxKO) mice) yielded markedly reduced trabecular and cortical bone mass. Treatment with anabolic PTH(1-34) (80 μg/kg/day) for 4 weeks failed to increase trabecular bone volume or cortical thickness in male and female P-Gsα(OsxKO) mice. Surprisingly, in both male and female mice, PTH administration significantly increased osteoblast numbers and bone formation rate in both control and P-Gsα(OsxKO) mice. In mice that express a mutated PTH1R that activates adenylyl cyclase and protein kinase A (PKA) via Gsα but not phospholipase C via Gq/11 (D/D mice), PTH significantly enhanced bone formation, indicating that phospholipase C activation is not required for increased bone turnover in response to PTH. Therefore, although the anabolic effect of intermittent PTH treatment on trabecular bone volume is blunted by deletion of Gsα in osteoblasts, PTH can stimulate osteoblast differentiation and bone formation. Together these findings suggest that alternative signaling pathways beyond Gsα and Gq/11 act downstream of PTH on osteoblast differentiation.
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Affiliation(s)
- Partha Sinha
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Piia Aarnisalo
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114,; Department of Clinical Chemistry, University of Helsinki and Helsinki University Central Hospital, Hospital District of Helsinki and Uusimaa, Laboratory Services, HUSLAB, 00029 HUS, Finland
| | - Rhiannon Chubb
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Ingrid J Poulton
- St. Vincent's Institute and Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Jun Guo
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Gregory Nachtrab
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Takaharu Kimura
- Division of Endocrinology, Stanford University School of Medicine, Stanford, California 94305
| | - Srilatha Swami
- Division of Endocrinology, Stanford University School of Medicine, Stanford, California 94305
| | - Hamid Saeed
- Division of Endocrinology, Stanford University School of Medicine, Stanford, California 94305
| | - Min Chen
- Metabolic Diseases Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Lee S Weinstein
- Metabolic Diseases Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Ernestina Schipani
- Departments of Orthopedic Surgery and Medicine, University of Michigan, Ann Arbor, Michigan 48109
| | - Natalie A Sims
- St. Vincent's Institute and Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Henry M Kronenberg
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Joy Y Wu
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114,; Division of Endocrinology, Stanford University School of Medicine, Stanford, California 94305,.
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20
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Takahashi JS. Molecular components of the circadian clock in mammals. Diabetes Obes Metab 2015; 17 Suppl 1:6-11. [PMID: 26332962 PMCID: PMC4560116 DOI: 10.1111/dom.12514] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 06/03/2015] [Indexed: 12/17/2022]
Abstract
The circadian clock mechanism in animals involves a transcriptional feedback loop in which the bHLH-PAS proteins CLOCK and BMAL1 form a transcriptional activator complex to activate the transcription of the Period and Cryptochrome genes, which in turn feed back to repress their own transcription. In the mouse liver, CLOCK and BMAL1 interact with the regulatory regions of thousands of genes, which are both cyclically and constitutively expressed. The circadian transcription in the liver is clustered in phase and this is accompanied by circadian occupancy of RNA polymerase II recruitment and initiation. These changes also lead to circadian fluctuations in histone H3 lysine4 trimethylation (H3K4me3) as well as H3 lysine9 acetylation (H3K9ac) and H3 lysine27 acetylation (H3K27ac). Thus, the circadian clock regulates global transcriptional poise and chromatin state by regulation of RNA polymerase II.
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Affiliation(s)
- Joseph S. Takahashi
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Correspondence: University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., NA4.118, Dallas, TX 75390-9111, USA,
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21
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Lee IT, Chang AS, Manandhar M, Shan Y, Fan J, Izumo M, Ikeda Y, Motoike T, Dixon S, Seinfeld JE, Takahashi JS, Yanagisawa M. Neuromedin s-producing neurons act as essential pacemakers in the suprachiasmatic nucleus to couple clock neurons and dictate circadian rhythms. Neuron 2015; 85:1086-102. [PMID: 25741729 DOI: 10.1016/j.neuron.2015.02.006] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 01/08/2015] [Accepted: 01/29/2015] [Indexed: 02/04/2023]
Abstract
Circadian behavior in mammals is orchestrated by neurons within the suprachiasmatic nucleus (SCN), yet the neuronal population necessary for the generation of timekeeping remains unknown. We show that a subset of SCN neurons expressing the neuropeptide neuromedin S (NMS) plays an essential role in the generation of daily rhythms in behavior. We demonstrate that lengthening period within Nms neurons is sufficient to lengthen period of the SCN and behavioral circadian rhythms. Conversely, mice without a functional molecular clock within Nms neurons lack synchronous molecular oscillations and coherent behavioral daily rhythms. Interestingly, we found that mice lacking Nms and its closely related paralog, Nmu, do not lose in vivo circadian rhythms. However, blocking vesicular transmission from Nms neurons with intact cell-autonomous clocks disrupts the timing mechanisms of the SCN, revealing that Nms neurons define a subpopulation of pacemakers that control SCN network synchrony and in vivo circadian rhythms through intercellular synaptic transmission.
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Affiliation(s)
- Ivan T Lee
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Alexander S Chang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Manabu Manandhar
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Yongli Shan
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Junmei Fan
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Mariko Izumo
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Yuichi Ikeda
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Toshiyuki Motoike
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Shelley Dixon
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Jeffrey E Seinfeld
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Joseph S Takahashi
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba 305-8575, Japan.
| | - Masashi Yanagisawa
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba 305-8575, Japan.
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22
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Ding X, Sun B, Huang J, Xu L, Pan J, Fang C, Tao Y, Hu S, Li R, Han X, Miao P, Wang Y, Yu J, Feng X. The role of miR-182 in regulating pineal CLOCK expression after hypoxia-ischemia brain injury in neonatal rats. Neurosci Lett 2015; 591:75-80. [PMID: 25684245 DOI: 10.1016/j.neulet.2015.02.026] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 01/14/2015] [Accepted: 02/11/2015] [Indexed: 11/18/2022]
Abstract
Circadian rhythm disorder is a common neurological deficit caused by neonatal hypoxic-ischemic brain damage (HIBD). However, little is known about its underlying mechanisms. Our previous studies revealed a significant elevation of clock genes at the protein, but not mRNA, levels in the pineal gland after neonatal HIBD. To investigate the mechanisms of post-transcriptional regulation on clock genes, we screened changes of miRNA levels in the pineal gland after neonatal HIBD using high-throughput arrays. Within the miRNAs whose expression was significantly down-regulated, we identified one miRNA (miR182) that targeted the 3'-untranslated region (3'-UTR) of Clock, a key component of clock genes, and played a crucial role in regulating CLOCK expression after oxygen-glucose deprivation in primarily cultured pinealocytes. Our findings therefore provide new insight on studies of therapeutic targets for circadian rhythm disturbance after neonatal HIBD.
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Affiliation(s)
- Xin Ding
- Division of Neonatology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Bin Sun
- Division of Neonatology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Jian Huang
- Center for Circadian Clocks, Medical College, Soochow University, Suzhou 215003, PR China
| | - Lixiao Xu
- Department of Hematology and Oncology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Jian Pan
- Department of Hematology and Oncology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Chen Fang
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, Suzhou 225003, PR China
| | - Yanfang Tao
- Department of Hematology and Oncology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Shukun Hu
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai 200040, PR China
| | - Ronghu Li
- Division of Neonatology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Xing Han
- Division of Neonatology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Po Miao
- Division of Neonatology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Ying Wang
- Division of Neonatology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Jian Yu
- Division of Neonatology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China
| | - Xing Feng
- Division of Neonatology, Affiliated Children's Hospital of Soochow University, Suzhou 215003, PR China.
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23
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Southey BR, Lee JE, Zamdborg L, Atkins N, Mitchell JW, Li M, Gillette MU, Kelleher NL, Sweedler JV. Comparing label-free quantitative peptidomics approaches to characterize diurnal variation of peptides in the rat suprachiasmatic nucleus. Anal Chem 2013; 86:443-52. [PMID: 24313826 PMCID: PMC3886391 DOI: 10.1021/ac4023378] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Mammalian
circadian rhythm is maintained by the suprachiasmatic nucleus (SCN)
via an intricate set of neuropeptides and other signaling molecules.
In this work, peptidomic analyses from two times of day were examined
to characterize variation in SCN peptides using three different label-free
quantitation approaches: spectral count, spectra index and SIEVE.
Of the 448 identified peptides, 207 peptides were analyzed by two
label-free methods, spectral count and spectral index. There were
24 peptides with significant (adjusted p-value <
0.01) differential peptide abundances between daytime and nighttime,
including multiple peptides derived from secretogranin II, cocaine
and amphetamine regulated transcript, and proprotein convertase subtilisin/kexin
type 1 inhibitor. Interestingly, more peptides were analyzable and
had significantly different abundances between the two time points
using the spectral count and spectral index methods than with a prior
analysis using the SIEVE method with the same data. The results of
this study reveal the importance of using the appropriate data analysis
approaches for label-free relative quantitation of peptides. The detection
of significant changes in so rich a set of neuropeptides reflects
the dynamic nature of the SCN and the number of influences such as
feeding behavior on circadian rhythm. Using spectral count and spectral
index, peptide level changes are correlated to time of day, suggesting
their key role in circadian function.
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Affiliation(s)
- Bruce R Southey
- Department of Animal Sciences, ‡Department of Chemistry, §Institute for Genomic Biology, ∥Neuroscience Program, ⊥Department of Cell and Developmental Biology, and ¶Beckman Institute, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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24
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Chen R, D'Alessandro M, Lee C. miRNAs are required for generating a time delay critical for the circadian oscillator. Curr Biol 2013; 23:1959-68. [PMID: 24094851 DOI: 10.1016/j.cub.2013.08.005] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 02/04/2013] [Accepted: 08/02/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Circadian clocks coordinate an organism's activities and regulate metabolic homeostasis in relation to daily environmental changes, most notably light/dark cycles. As in other organisms, the timekeeping mechanism in mammals depends on a self-sustaining transcriptional negative feedback loop with a built-in time delay in feedback inhibition. Although the time delay is essential for generating a slow, self-sustaining negative feedback loop with a period close to 24 hr, the exact mechanisms underlying the time delay are not known. RESULTS Here, we show that RNAi mediated by microRNAs (miRNAs) is an essential mechanism in generating the time delay. In Dicer-deficient (and thus miRNA-deficient) cells and mice, circadian rhythms were dramatically shortened (by ∼2 hr), although the rhythms remained robust. The period shortening was caused by faster PER1 and PER2 translation in the Dicer-deficient cells. We also identified three specific miRNAs that regulate Per expression and showed that knockdown of these miRNAs in wild-type cells also shortened the circadian period. CONCLUSIONS Consistent with the canonical function of miRNAs as translational modulators of target genes and their widespread roles in cell physiology, circadian rhythms are also modulated by miRNA-mediated RNAi acting on posttranscriptional regulation of key clock genes. Our present study definitively shows that RNAi is an important modulator of circadian rhythms by controlling the pace of PER synthesis and presents a novel layer of regulation for the clock.
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Affiliation(s)
- Rongmin Chen
- Department of Biomedical Sciences, Neuroscience Program, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306, USA
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25
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Yoo SH, Mohawk JA, Siepka SM, Shan Y, Huh SK, Hong HK, Kornblum I, Kumar V, Koike N, Xu M, Nussbaum J, Liu X, Chen Z, Chen ZJ, Green CB, Takahashi JS. Competing E3 ubiquitin ligases govern circadian periodicity by degradation of CRY in nucleus and cytoplasm. Cell 2013; 152:1091-105. [PMID: 23452855 DOI: 10.1016/j.cell.2013.01.055] [Citation(s) in RCA: 250] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 11/10/2012] [Accepted: 01/30/2013] [Indexed: 12/21/2022]
Abstract
Period determination in the mammalian circadian clock involves the turnover rate of the repressors CRY and PER. We show that CRY ubiquitination engages two competing E3 ligase complexes that either lengthen or shorten circadian period in mice. Cloning of a short-period circadian mutant, Past-time, revealed a glycine to glutamate missense mutation in Fbxl21, an F-box protein gene that is a paralog of Fbxl3 that targets the CRY proteins for degradation. While loss of function of FBXL3 leads to period lengthening, mutation of Fbxl21 causes period shortening. FBXL21 forms an SCF E3 ligase complex that slowly degrades CRY in the cytoplasm but antagonizes the stronger E3 ligase activity of FBXL3 in the nucleus. FBXL21 plays a dual role: protecting CRY from FBXL3 degradation in the nucleus and promoting CRY degradation within the cytoplasm. Thus, the balance and cellular compartmentalization of competing E3 ligases for CRY determine circadian period of the clock in mammals.
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Affiliation(s)
- Seung-Hee Yoo
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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26
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Shimomura K, Kumar V, Koike N, Kim TK, Chong J, Buhr ED, Whiteley AR, Low SS, Omura C, Fenner D, Owens JR, Richards M, Yoo SH, Hong HK, Vitaterna MH, Bass J, Pletcher MT, Wiltshire T, Hogenesch J, Lowrey PL, Takahashi JS. Usf1, a suppressor of the circadian Clock mutant, reveals the nature of the DNA-binding of the CLOCK:BMAL1 complex in mice. eLife 2013; 2:e00426. [PMID: 23580255 PMCID: PMC3622178 DOI: 10.7554/elife.00426] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 02/12/2013] [Indexed: 11/13/2022] Open
Abstract
Genetic and molecular approaches have been critical for elucidating the mechanism of the mammalian circadian clock. Here, we demonstrate that the ClockΔ19 mutant behavioral phenotype is significantly modified by mouse strain genetic background. We map a suppressor of the ClockΔ19 mutation to a ∼900 kb interval on mouse chromosome 1 and identify the transcription factor, Usf1, as the responsible gene. A SNP in the promoter of Usf1 causes elevation of its transcript and protein in strains that suppress the Clock mutant phenotype. USF1 competes with the CLOCK:BMAL1 complex for binding to E-box sites in target genes. Saturation binding experiments demonstrate reduced affinity of the CLOCKΔ19:BMAL1 complex for E-box sites, thereby permitting increased USF1 occupancy on a genome-wide basis. We propose that USF1 is an important modulator of molecular and behavioral circadian rhythms in mammals. DOI:http://dx.doi.org/10.7554/eLife.00426.001.
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Affiliation(s)
- Kazuhiro Shimomura
- Center for Functional Genomics, Department of Neurobiology, Center for Sleep and Circadian Biology, Northwestern University, Evanston, United States
| | - Vivek Kumar
- Department of Neuroscience, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Nobuya Koike
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, United States
| | - Tae-Kyung Kim
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jason Chong
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - Ethan D Buhr
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - Andrew R Whiteley
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - Sharon S Low
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - Chiaki Omura
- Department of Neurobiology, Center for Functional Genomics, Northwestern University, Evanston, United States
| | - Deborah Fenner
- Department of Neurobiology, Center for Functional Genomics, Northwestern University, Evanston, United States
| | - Joseph R Owens
- Department of Neurobiology, Center for Sleep and Circadian Biology, Northwestern University, Evanston, United States
| | - Marc Richards
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - Seung-Hee Yoo
- Department of Neuroscience, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Hee-Kyung Hong
- Department of Neurobiology, Center for Functional Genomics, Northwestern University, Evanston, United States
| | - Martha H Vitaterna
- Center for Functional Genomics, Department of Neurobiology, Center for Sleep and Circadian Biology, Northwestern University, Evanston, United States
| | - Joseph Bass
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Mathew T Pletcher
- Department of Genomics, Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Tim Wiltshire
- Department of Genomics, Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - John Hogenesch
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Phillip L Lowrey
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - Joseph S Takahashi
- Department of Neuroscience, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States
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27
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Wan M, Kaundal R, Huang H, Zhao J, Yang X, Chaiyachati BH, Li S, Chi T. A general approach for controlling transcription and probing epigenetic mechanisms: application to the CD4 locus. THE JOURNAL OF IMMUNOLOGY 2013; 190:737-47. [PMID: 23293358 DOI: 10.4049/jimmunol.1201278] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Synthetic regulatory proteins such as tetracycline (tet)-controlled transcription factors are potentially useful for repression as well as ectopic activation of endogenous genes and also for probing their regulatory mechanisms, which would offer a versatile genetic tool advantageous over conventional gene targeting methods. In this study, we provide evidence supporting this concept using Cd4 as a model. CD4 is expressed in double-positive and CD4 cells but irreversibly silenced in CD8 cells. The silencing is mediated by heterochromatin established during CD8 lineage development via transient action of the Cd4 silencer; once established, the heterochromatin becomes self-perpetuating independently of the Cd4 silencer. Using a tet-sensitive Cd4 allele harboring a removable Cd4 silencer, we found that a tet-controlled repressor recapitulated the phenotype of Cd4-deficient mice, inhibited Cd4 expression in a reversible and dose-dependent manner, and could surprisingly replace the Cd4 silencer to induce irreversible Cd4 silencing in CD8 cells, thus suggesting the Cd4 silencer is not the (only) determinant of heterochromatin formation. In contrast, a tet-controlled activator reversibly disrupted Cd4 silencing in CD8 cells. The Cd4 silencer impeded this disruption but was not essential for its reversal, which revealed a continuous role of the silencer in mature CD8 cells while exposing a remarkable intrinsic self-regenerative ability of heterochromatin after forced disruption. These data demonstrate an effective approach for gene manipulation and provide insights into the epigenetic Cd4 regulatory mechanisms that are otherwise difficult to obtain.
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Affiliation(s)
- Mimi Wan
- Department of Immunobiology, Yale University Medical School, New Haven, CT 06520, USA
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28
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Lee JE, Zamdborg L, Southey BR, Atkins N, Mitchell JW, Li M, Gillette MU, Kelleher NL, Sweedler JV. Quantitative peptidomics for discovery of circadian-related peptides from the rat suprachiasmatic nucleus. J Proteome Res 2013; 12:585-93. [PMID: 23256577 DOI: 10.1021/pr300605p] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In mammals the suprachiasmatic nucleus (SCN), the master circadian clock, is sensitive to light input via the optic chiasm and synchronizes many daily biological rhythms. Here we explore variations in the expression levels of neuropeptides present in the SCN of rats using a label-free quantification approach that is based on integrating peak intensities between daytime, Zeitgeber time (ZT) 6, and nighttime, ZT 18. From nine analyses comparing the levels between these two time points, 10 endogenous peptides derived from eight prohormones exhibited significant differences in their expression levels (adjusted p-value <0.05). Of these, seven peptides derived from six prohormones, including GRP, PACAP, and CART, exhibited ≥ 30% increases at ZT 18, and the VGRPEWWMDYQ peptide derived from proenkephalin A showed a >50% increase at nighttime. Several endogenous peptides showing statistically significant changes in this study have not been previously reported to alter their levels as a function of time of day, nor have they been implicated in prior functional SCN studies. This information on peptide expression changes serves as a resource for discovering unknown peptide regulators that affect circadian rhythms in the SCN.
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Affiliation(s)
- Ji Eun Lee
- Department of Chemistry, Beckman Institute, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, USA
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29
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Hughes ME, Hong HK, Chong JL, Indacochea AA, Lee SS, Han M, Takahashi JS, Hogenesch JB. Brain-specific rescue of Clock reveals system-driven transcriptional rhythms in peripheral tissue. PLoS Genet 2012; 8:e1002835. [PMID: 22844252 PMCID: PMC3405989 DOI: 10.1371/journal.pgen.1002835] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 05/29/2012] [Indexed: 11/17/2022] Open
Abstract
The circadian regulatory network is organized in a hierarchical fashion, with a central oscillator in the suprachiasmatic nuclei (SCN) orchestrating circadian oscillations in peripheral tissues. The nature of the relationship between central and peripheral oscillators, however, is poorly understood. We used the tetOFF expression system to specifically restore Clock function in the brains of Clock(Δ19) mice, which have compromised circadian clocks. Rescued mice showed normal locomotor rhythms in constant darkness, with activity period lengths approximating wildtype controls. We used microarray analysis to assess whether brain-specific rescue of circadian rhythmicity was sufficient to restore circadian transcriptional output in the liver. Compared to Clock mutants, Clock-rescue mice showed significantly larger numbers of cycling transcripts with appropriate phase and period lengths, including many components of the core circadian oscillator. This indicates that the SCN oscillator overcomes local circadian defects and signals directly to the molecular clock. Interestingly, the vast majority of core clock genes in liver were responsive to Clock expression in the SCN, suggesting that core clock genes in peripheral tissues are intrinsically sensitive to SCN cues. Nevertheless, most circadian output in the liver was absent or severely low-amplitude in Clock-rescue animals, demonstrating that the majority of peripheral transcriptional rhythms depend on a fully functional local circadian oscillator. We identified several new system-driven rhythmic genes in the liver, including Alas1 and Mfsd2. Finally, we show that 12-hour transcriptional rhythms (i.e., circadian "harmonics") are disrupted by Clock loss-of-function. Brain-specific rescue of Clock converted 12-hour rhythms into 24-hour rhythms, suggesting that signaling via the central circadian oscillator is required to generate one of the two daily peaks of expression. Based on these data, we conclude that 12-hour rhythms are driven by interactions between central and peripheral circadian oscillators.
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Affiliation(s)
- Michael E Hughes
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT, USA
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30
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Huang N, Chelliah Y, Shan Y, Taylor CA, Yoo SH, Partch C, Green CB, Zhang H, Takahashi JS. Crystal structure of the heterodimeric CLOCK:BMAL1 transcriptional activator complex. Science 2012; 337:189-94. [PMID: 22653727 PMCID: PMC3694778 DOI: 10.1126/science.1222804] [Citation(s) in RCA: 223] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The circadian clock in mammals is driven by an autoregulatory transcriptional feedback mechanism that takes approximately 24 hours to complete. A key component of this mechanism is a heterodimeric transcriptional activator consisting of two basic helix-loop-helix PER-ARNT-SIM (bHLH-PAS) domain protein subunits, CLOCK and BMAL1. Here, we report the crystal structure of a complex containing the mouse CLOCK:BMAL1 bHLH-PAS domains at 2.3 Å resolution. The structure reveals an unusual asymmetric heterodimer with the three domains in each of the two subunits--bHLH, PAS-A, and PAS-B--tightly intertwined and involved in dimerization interactions, resulting in three distinct protein interfaces. Mutations that perturb the observed heterodimer interfaces affect the stability and activity of the CLOCK:BMAL1 complex as well as the periodicity of the circadian oscillator. The structure of the CLOCK:BMAL1 complex is a starting point for understanding at an atomic level the mechanism driving the mammalian circadian clock.
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Affiliation(s)
- Nian Huang
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yogarany Chelliah
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yongli Shan
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Clinton A. Taylor
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Molecular Biophysics Graduate Program, Division of Basic Science, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Seung-Hee Yoo
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Carrie Partch
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Carla B. Green
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hong Zhang
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joseph S. Takahashi
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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31
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Wisor JP. A metabolic-transcriptional network links sleep and cellular energetics in the brain. Pflugers Arch 2012; 463:15-22. [PMID: 21927810 PMCID: PMC4086657 DOI: 10.1007/s00424-011-1030-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 09/05/2011] [Accepted: 09/07/2011] [Indexed: 12/22/2022]
Abstract
This review proposes a mechanistic link between cellular metabolic status, transcriptional regulatory changes and sleep. Sleep loss is associated with changes in cellular metabolic status in the brain. Metabolic sensors responsive to cellular metabolic status regulate the circadian clock transcriptional network. Modifications of the transcriptional activity of circadian clock genes affect sleep/wake state changes. Changes in sleep state reverse sleep loss-induced changes in cellular metabolic status. It is thus proposed that the regulation of circadian clock genes by cellular metabolic sensors is a critical intermediate step in the link between cellular metabolic status and sleep. Studies of this regulatory relationship may offer insights into the function of sleep at the cellular level.
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Affiliation(s)
- Jonathan P Wisor
- WWAMI Medical Education Program and Department of Veterinary Comparative Anatomy, Pharmacology and Physiology, Washington State University, Spokane, WA, USA.
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32
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Husse J, Zhou X, Shostak A, Oster H, Eichele G. Synaptotagmin10-Cre, a driver to disrupt clock genes in the SCN. J Biol Rhythms 2011; 26:379-89. [PMID: 21921292 DOI: 10.1177/0748730411415363] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Surgical lesion of the suprachiasmatic nuclei (SCN) profoundly affects the circadian timing system. A complication of SCN ablations is the concomitant scission of SCN afferents and efferents. Genetic disruption of the molecular clockwork in the SCN provides a complementary, less invasive experimental approach. The authors report the generation and functional analysis of a new Cre recombinase driver mouse that evokes homologous recombination with high efficiency in the SCN. They inserted the Cre recombinase cDNA into the Synaptotagmin10 (Syt10) locus, a gene strongly expressed in the SCN. Heterozygous Synaptotagmin10-Cre (Syt10(Cre)) mice have no obvious circadian locomotor phenotype, and homozygous animals show slightly reduced light-induced phase delays. Crosses of Syt10(Cre) mice with β-galactosidase reporter animals revealed strong Cre activity in the vast majority of SCN cells. Cre activity is not detected in nonneuronal tissues with the exception of the testis. The authors demonstrate that conditionally deleting the clock gene Bmal1 using the Syt10(Cre) driver renders animals arrhythmic.
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Affiliation(s)
- Jana Husse
- Genes and Behavior Department, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
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33
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Ko ML, Shi L, Tsai JY, Young ME, Neuendorff N, Earnest DJ, Ko GYP. Cardiac-specific mutation of Clock alters the quantitative measurements of physical activities without changing behavioral circadian rhythms. J Biol Rhythms 2011; 26:412-22. [PMID: 21921295 PMCID: PMC3181102 DOI: 10.1177/0748730411414170] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Even though peripheral circadian oscillators in the cardiovascular system are known to exist, the daily rhythms of the cardiovascular system are mainly attributed to autonomic or hormonal inputs under the control of the central oscillator, the suprachiasmatic nucleus (SCN). In order to examine the role of peripheral oscillators in the cardiovascular system, we used a transgenic mouse where the Clock gene is specifically disrupted in cardiomyocytes. In this cardiomyocyte-specific CLOCK mutant (CCM) mouse model, the circadian input from the SCN remains intact. Both CCM and wild-type (WT) littermates displayed circadian rhythms in wheel-running behavior. However, the overall wheel-running activities were significantly lower in CCM mice compared to WT over the course of 5 weeks, indicating that CCM mice either have lower baseline physical activities or they have lower physical adaptation abilities because daily wheel running, like routine exercise, induces physical adaptation over a period of time. Upon further biochemical analysis, it was revealed that the diurnal oscillations of phosphorylation states of several kinases and protein expression of the L-type voltage-gated calcium channel (L-VGCC) α1D subunit found in WT hearts were abolished in CCM hearts, indicating that in mammalian hearts, the daily oscillations of the activities of these kinases and L-VGCCs were downstream elements of the cardiac core oscillators. However, the phosphorylation of p38 MAPK exhibited robust diurnal rhythms in both WT and CCM hearts, indicating that cardiac p38 could be under the influence of the central clock through neurohormonal signals or be part of the circadian input pathway in cardiomyocytes. Taken together, these results indicate that the cardiac core oscillators have an impact in regulating circadian rhythmicities and cardiac function.
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Affiliation(s)
- Michael L. Ko
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX
| | - Liheng Shi
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX
| | - Ju-Yun Tsai
- US Department of Agriculture/Agricultural Research Service Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Martin E. Young
- Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Nichole Neuendorff
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, College Station, TX
| | - David J. Earnest
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, College Station, TX
| | - Gladys Y.-P. Ko
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX
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34
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Yu EA, Weaver DR. Disrupting the circadian clock: gene-specific effects on aging, cancer, and other phenotypes. Aging (Albany NY) 2011; 3:479-93. [PMID: 21566258 PMCID: PMC3156599 DOI: 10.18632/aging.100323] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The circadian clock imparts 24-hour rhythmicity on gene expression and cellular physiology in virtually all cells. Disruption of the genes necessary for the circadian clock to function has diverse effects, including aging-related phenotypes. Some circadian clock genes have been described as tumor suppressors, while other genes have less clear functions in aging and cancer. In this Review, we highlight a recent study [Dubrovsky et al., Aging 2: 936-944, 2010] and discuss the much larger field examining the relationship between circadian clock genes, circadian rhythmicity, aging-related phenotypes, and cancer.
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Affiliation(s)
- Elizabeth A Yu
- Department of Neurobiology, MD/PhD Program, University of Massachusetts Medical School, Worcester, 01605, USA
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35
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Mohawk JA, Takahashi JS. Cell autonomy and synchrony of suprachiasmatic nucleus circadian oscillators. Trends Neurosci 2011; 34:349-58. [PMID: 21665298 DOI: 10.1016/j.tins.2011.05.003] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 05/04/2011] [Accepted: 05/10/2011] [Indexed: 11/18/2022]
Abstract
The suprachiasmatic nucleus (SCN) of the hypothalamus is the site of the master circadian pacemaker in mammals. The individual cells of the SCN are capable of functioning independently from one another and therefore must form a cohesive circadian network through intercellular coupling. The network properties of the SCN lead to coordination of circadian rhythms among its neurons and neuronal subpopulations. There is increasing evidence for multiple interconnected oscillators within the SCN, and in this review we will highlight recent advances in our knowledge of the complex organization and function of the cellular and network-level SCN clock. Understanding the way in which synchrony is achieved between cells in the SCN will provide insight into the means by which this important nucleus orchestrates circadian rhythms throughout the organism.
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Affiliation(s)
- Jennifer A Mohawk
- Department of Neuroscience and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9111, USA
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36
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Lee B, Li A, Hansen KF, Cao R, Yoon JH, Obrietan K. CREB influences timing and entrainment of the SCN circadian clock. J Biol Rhythms 2011; 25:410-20. [PMID: 21135157 DOI: 10.1177/0748730410381229] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The transcriptional feedback circuit, which is at the core of the suprachiasmatic nucleus (SCN) circadian (i.e., 24 h) clock, is tightly coupled to both external entrainment cues, such as light, as well as rhythmic cues that arise on a system-wide level within the SCN. One potential signaling pathway by which these cues are conveyed to the molecular clock is the CREB/CRE transcriptional cascade. In this study, we employed a tetracycline-inducible CREB repressor mouse strain, in which approximately 60% of the SCN neurons express the transgene, to test CREB functionality in the clock and its effects on overt rhythmicity. We show that attenuated CREB signaling in the SCN led to a significant reduction in light-evoked clock entrainment. An examination of circadian timing revealed that CREB repressor mice exhibited normal free-running rhythms in the absence of external lighting cues. However, under conditions of constant light, which typically leads to a lengthening of the circadian period, CREB repressor mice exhibited a dramatic arrhythmic phenotype, which could be reversed with doxycycline. At a cellular level, the repression of CREB led to a significant reduction in both the expression of the circadian clock proteins PERIOD1 and PERIOD2 and the clock output hormones AVP and VIP. Together, these data support the idea that the CRE transcriptional pathway orchestrates transcriptional events that are essential for both the maintenance of SCN timing and light entrainment of the circadian clock.
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Affiliation(s)
- Boyoung Lee
- Department of Neuroscience, Ohio State University, Columbus, OH, USA
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37
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Fujimoto K, Araki K, McCarthy DM, Sims JR, Ren JQ, Zhang X, Bhide PG. A transgenic mouse model of neuroepithelial cell specific inducible overexpression of dopamine D1-receptor. Neuroscience 2010; 170:961-70. [PMID: 20674683 DOI: 10.1016/j.neuroscience.2010.07.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 07/14/2010] [Accepted: 07/18/2010] [Indexed: 01/01/2023]
Abstract
Dopamine and its receptors appear in the brain during early embryonic period suggesting a role for dopamine in brain development. In fact, dopamine receptor imbalance resulting from impaired physiological balance between D1- and D2-receptor activities can perturb brain development and lead to persisting changes in brain structure and function. Dopamine receptor imbalance can be produced experimentally using pharmacological or genetic methods. Pharmacological methods tend to activate or antagonize the receptors in all cell types. In the traditional gene knockout models the receptor imbalance occurs during development and also at maturity. Therefore, assaying the effects of dopamine imbalance on specific cell types (e.g. precursor versus postmitotic cells) or at specific periods of brain development (e.g. pre- or postnatal periods) is not feasible in these models. We describe a novel transgenic mouse model based on the tetracycline dependent inducible gene expression system in which dopamine D1-receptor transgene expression is induced selectively in neuroepithelial cells of the embryonic brain at experimenter-chosen intervals of brain development. In this model, doxycycline-induced expression of the transgene causes significant overexpression of the D1-receptor and significant reductions in the incorporation of the S-phase marker bromodeoxyuridine into neuroepithelial cells of the basal and dorsal telencephalon indicating marked effects on telencephalic neurogenesis. The D1-receptor overexpression occurs at higher levels in the medial ganglionic eminence (MGE) than the lateral ganglionic eminence (LGE) or cerebral wall (CW). Moreover, although the transgene is induced selectively in the neuroepithelium, D1-receptor protein overexpression appears to persist in postmitotic cells. The mouse model can be modified for neuroepithelial cell-specific inducible expression of other transgenes or induction of the D1-receptor transgene in other cells in specific brain regions by crossbreeding the mice with transgenic mouse lines available already.
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Affiliation(s)
- K Fujimoto
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02129, USA
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38
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Abstract
In mammals, many physiological processes present diurnal variations, and most of these rhythms persist even in absence of environmental timing cues. These endogenous circadian rhythms are generated by intracellular timing mechanisms termed circadian clocks. In mammals, the master clock is located in the suprachiasmatic nuclei (SCN), but other brain regions and most peripheral tissues contain circadian clocks. These clocks are responsive to environmental cues, in particular light/dark and feeding/fasting cycles. In the last few years, tissue-specific knock-out and transgenic mouse models have helped to define the physiological roles of specific clocks. Recent reports indicate that the clock-physiology connection is bi-directional, and physiological cues, in particular the energetic status of the cell, can feed into the clockwork. This effect was discovered unexpectedly in molecular analyses of clock protein modifications. Beyond the positive and negative transcription/translation feedback loops of the molecular oscillator lies another level of complexity. Post-translational modifications of clock proteins are both critical for the timing of the clock feedback mechanism and to provide regulatory fine-tuning. This review summarizes recent advances in our understanding of the roles of peripheral clocks and of post-translational modifications occurring on clock proteins. These two matters are at the intersection of physiology, metabolism, and the circadian system.
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Affiliation(s)
- David Duguay
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, 6875 LaSalle Blvd., Montreal, QC, Canada
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NAKAMURA W. Behavioral analysis of circadian rhythms: Entraining the circadian clock and determining the food-entrainable oscillator mechanism. Sleep Biol Rhythms 2010. [DOI: 10.1111/j.1479-8425.2010.00436.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Chen R, Schirmer A, Lee Y, Lee H, Kumar V, Yoo SH, Takahashi JS, Lee C. Rhythmic PER abundance defines a critical nodal point for negative feedback within the circadian clock mechanism. Mol Cell 2009; 36:417-30. [PMID: 19917250 PMCID: PMC3625733 DOI: 10.1016/j.molcel.2009.10.012] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Revised: 05/27/2009] [Accepted: 08/13/2009] [Indexed: 11/21/2022]
Abstract
Circadian rhythms in mammals are generated by a transcriptional negative feedback loop that is driven primarily by oscillations of PER and CRY, which inhibit their own transcriptional activators, CLOCK and BMAL1. Current models posit that CRY is the dominant repressor, while PER may play an accessory role. In this study, however, constitutive expression of PER, and not CRY1, severely disrupted the clock in fibroblasts and liver. Furthermore, constitutive expression of PER2 in the brain and SCN of transgenic mice caused a complete loss of behavioral circadian rhythms in a conditional and reversible manner. These results demonstrate that rhythmic levels of PER2, rather than CRY1, are critical for circadian oscillations in cells and in the intact organism. Our biochemical evidence supports an elegant mechanism for the disparity: PER2 directly and rhythmically binds to CLOCK:BMAL1, while CRY only interacts indirectly; PER2 bridges CRY and CLOCK:BMAL1 to drive the circadian negative feedback loop.
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Affiliation(s)
- Rongmin Chen
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306
| | - Aaron Schirmer
- Howard Hughes Medical Institute, Department of Neurobiology and Physiology, Northwestern University, 2205 Tech Drive, Evanston, IL 60208
| | - Yongjin Lee
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306
| | - Hyeongmin Lee
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306
| | - Vivek Kumar
- Howard Hughes Medical Institute, Department of Neurobiology and Physiology, Northwestern University, 2205 Tech Drive, Evanston, IL 60208
| | - Seung-Hee Yoo
- Howard Hughes Medical Institute, Department of Neurobiology and Physiology, Northwestern University, 2205 Tech Drive, Evanston, IL 60208
| | - Joseph S. Takahashi
- Howard Hughes Medical Institute, Department of Neurobiology and Physiology, Northwestern University, 2205 Tech Drive, Evanston, IL 60208
| | - Choogon Lee
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306
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Lee JE, Atkins N, Hatcher NG, Zamdborg L, Gillette MU, Sweedler JV, Kelleher NL. Endogenous peptide discovery of the rat circadian clock: a focused study of the suprachiasmatic nucleus by ultrahigh performance tandem mass spectrometry. Mol Cell Proteomics 2009; 9:285-97. [PMID: 19955084 DOI: 10.1074/mcp.m900362-mcp200] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Understanding how a small brain region, the suprachiasmatic nucleus (SCN), can synchronize the body's circadian rhythms is an ongoing research area. This important time-keeping system requires a complex suite of peptide hormones and transmitters that remain incompletely characterized. Here, capillary liquid chromatography and FTMS have been coupled with tailored software for the analysis of endogenous peptides present in the SCN of the rat brain. After ex vivo processing of brain slices, peptide extraction, identification, and characterization from tandem FTMS data with <5-ppm mass accuracy produced a hyperconfident list of 102 endogenous peptides, including 33 previously unidentified peptides, and 12 peptides that were post-translationally modified with amidation, phosphorylation, pyroglutamylation, or acetylation. This characterization of endogenous peptides from the SCN will aid in understanding the molecular mechanisms that mediate rhythmic behaviors in mammals.
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Affiliation(s)
- Ji Eun Lee
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Zhou H, Huang C, Yang M, Landel CP, Xia PY, Liu YJ, Xia XG. Developing tTA transgenic rats for inducible and reversible gene expression. Int J Biol Sci 2009; 5:171-81. [PMID: 19214245 PMCID: PMC2640494 DOI: 10.7150/ijbs.5.171] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Accepted: 01/28/2009] [Indexed: 11/30/2022] Open
Abstract
To develop transgenic lines for conditional expression of desired genes in rats, we generated several lines of the transgenic rats carrying the tetracycline-controlled transactivator (tTA) gene. Using a vigorous, ubiquitous promoter to drive the tTA transgene, we obtained widespread expression of tTA in various tissues. Expression of tTA was sufficient to strongly activate its reporter gene, but was below the toxicity threshold. We examined the dynamics of Doxycycline (Dox)-regulated gene expression in transgenic rats. In the two transmittable lines, tTA-mediated activation of the reporter gene was fully subject to regulation by Dox. Dox dose-dependently suppressed tTA-activated gene expression. The washout time for the effects of Dox was dose-dependent. We tested a complex regime of Dox administration to determine the optimal effectiveness and washout duration. Dox was administered at a high dose (500 μg/ml in drinking water) for two days to reach the effective concentration, and then was given at a low dose (20 μg/ml) to maintain effectiveness. This regimen of Dox administration can achieve a quick switch between ON and OFF statuses of tTA-activated gene expression. In addition, administration of Dox to pregnant rats fully suppressed postnatal tTA-activated gene expression in their offspring. Sufficient levels of Dox are present in mother's milk to produce maximal efficacy in nursing neonates. Administration of Dox to pregnant or nursing rats can provide a continual suppression of tTA-dependent gene expression during embryonic and postnatal development. The tTA transgenic rat allows for inducible and reversible gene expression in the rat; this important tool will be valuable in the development of genetic rat models of human diseases.
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Affiliation(s)
- Hongxia Zhou
- Department of Pathology, Anatomy & Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Son GH, Chung S, Choe HK, Kim HD, Baik SM, Lee H, Lee HW, Choi S, Sun W, Kim H, Cho S, Lee KH, Kim K. Adrenal peripheral clock controls the autonomous circadian rhythm of glucocorticoid by causing rhythmic steroid production. Proc Natl Acad Sci U S A 2008; 105:20970-5. [PMID: 19091946 PMCID: PMC2634940 DOI: 10.1073/pnas.0806962106] [Citation(s) in RCA: 234] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Indexed: 11/18/2022] Open
Abstract
Glucocorticoid (GC) is an adrenal steroid with diverse physiological effects. It undergoes a robust daily oscillation, which has been thought to be driven by the master circadian clock in the suprachiasmatic nucleus of the hypothalamus via the hypothalamus-pituitary-adrenal axis. However, we show that the adrenal gland has its own clock and that the peripheral clockwork is tightly linked to steroidogenesis by the steroidogenic acute regulatory protein. Examination of mice with adrenal-specific knockdown of the canonical clock protein BMAL1 reveals that the adrenal clock machinery is required for circadian GC production. Furthermore, behavioral rhythmicity is drastically affected in these animals, together with altered expression of Period1, but not Period2, in several peripheral organs. We conclude that the adrenal peripheral clock plays an essential role in harmonizing the mammalian circadian timing system by generating a robust circadian GC rhythm.
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Affiliation(s)
- Gi Hoon Son
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea
| | - Sooyoung Chung
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea
| | - Han Kyoung Choe
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea
| | - Hee-Dae Kim
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea
| | - Sun-Mee Baik
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea
| | - Hankyu Lee
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea
| | - Han-Woong Lee
- Department of Biochemistry, Yonsei University, Seoul 120-749, Korea
| | - Sukwoo Choi
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea
| | - Woong Sun
- Department of Anatomy, Korea University College of Medicine, Seoul 136-705, Korea; and
| | - Hyun Kim
- Department of Anatomy, Korea University College of Medicine, Seoul 136-705, Korea; and
| | - Sehyung Cho
- Department of Life and Nanopharmaceutical Science and Age-Related and Brain Diseases Research Center, Kyung Hee University, Seoul 130-701, Korea
| | - Kun Ho Lee
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea
| | - Kyungjin Kim
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea
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Abstract
The circadian system orchestrates the temporal organization of many aspects of physiology, including metabolism, in synchrony with the 24 hr rotation of the Earth. Like the metabolic system, the circadian system is a complex feedback network that involves interactions between the central nervous system and peripheral tissues. Emerging evidence suggests that circadian regulation is intimately linked to metabolic homeostasis and that dysregulation of circadian rhythms can contribute to disease. Conversely, metabolic signals also feed back into the circadian system, modulating circadian gene expression and behavior. Here, we review the relationship between the circadian and metabolic systems and the implications for cardiovascular disease, obesity, and diabetes.
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Nakamura W, Yamazaki S, Nakamura TJ, Shirakawa T, Block GD, Takumi T. In vivo monitoring of circadian timing in freely moving mice. Curr Biol 2008; 18:381-5. [PMID: 18334203 DOI: 10.1016/j.cub.2008.02.024] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2007] [Revised: 01/16/2008] [Accepted: 02/04/2008] [Indexed: 10/22/2022]
Abstract
In mammals, the principal circadian pacemaker driving daily physiology and behavioral rhythms is located in the suprachiasmatic nucleus (SCN) in the anterior hypothalamus. The neural output of SCN is essential for the circadian regulation of behavioral activity. Although remarkable progress has been made in revealing the molecular basis of circadian rhythm generation within the SCN, the output pathways by which the SCN exert control over circadian rhythms are not well understood. Most SCN efferents target the subparaventricular zone (SPZ), which resides just dorsal to the SCN. This output pathway has been proposed as a major component involved in the outflow for circadian regulation. We have examined the downstream pathway of the central clock by means of multiunit neural activity (MUA) in freely moving mice. SCN neural activity is tightly coupled to environmental photic input and anticorrelated with MUA rhythm in the SPZ. In Clock mutant mice exhibiting attenuated circadian locomotor rhythmicity, MUA rhythmicity in the SCN and SPZ is similarly blunted. These results suggest that the SPZ plays a functional role in relaying circadian and photic signals to centers involved in generating behavioral activity.
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Abstract
A network of feedback loops constitutes the basis for circadian timing in mammals. Complex transcriptional, post-transcriptional and post-translational events are also involved in the ticking of circadian clocks, allowing them to run autonomously with their characteristic, near-24h period. Central to the molecular mechanism is the CLOCK/BMAL1 heterodimer of transcription factors. Recent data using Clock knock-out mice however suggest that CLOCK may not be as mandatory as initially suggested from data gathered in the Clock mutant mouse model. Indeed, it appears that the Clock homolog Npas2 is able to functionally compensate for Clock genetic ablation. Furthermore, real-time imaging techniques using different clock genes knock-out lines established on a PER2 ::Luc knock-in background now demonstrate that persistent rhythmicity in the suprachiasmatic nuclei likely arises as a consequence of combined genetic redundancy and strong intercellular coupling, the latter characteristic being likely weakened in peripheral tissues such as liver or lung. The present review aims at summarizing current knowledge of the molecular basis of circadian clocks and possible differences between central and peripheral clocks in light of recent findings in Clock knock-out mice.
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Affiliation(s)
- Hugues Dardente
- School of Biological Sciences, Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, Ecosse, Royaume-Uni.
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Dominant-negative CK2alpha induces potent effects on circadian rhythmicity. PLoS Genet 2007; 4:e12. [PMID: 18208335 PMCID: PMC2211540 DOI: 10.1371/journal.pgen.0040012] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 12/04/2007] [Indexed: 11/19/2022] Open
Abstract
Circadian clocks organize the precise timing of cellular and behavioral events. In Drosophila, circadian clocks consist of negative feedback loops in which the clock component PERIOD (PER) represses its own transcription. PER phosphorylation is a critical step in timing the onset and termination of this feedback. The protein kinase CK2 has been linked to circadian timing, but the importance of this contribution is unclear; it is not certain where and when CK2 acts to regulate circadian rhythms. To determine its temporal and spatial functions, a dominant negative mutant of the catalytic alpha subunit, CK2αTik, was targeted to circadian neurons. Behaviorally, CK2αTik induces severe period lengthening (∼33 h), greater than nearly all known circadian mutant alleles, and abolishes detectable free-running behavioral rhythmicity at high levels of expression. CK2αTik, when targeted to a subset of pacemaker neurons, generates period splitting, resulting in flies exhibiting both long and near 24-h periods. These behavioral effects are evident even when CK2αTik expression is induced only during adulthood, implicating an acute role for CK2α function in circadian rhythms. CK2αTik expression results in reduced PER phosphorylation, delayed nuclear entry, and dampened cycling with elevated trough levels of PER. Heightened trough levels of per transcript accompany increased protein levels, suggesting that CK2αTik disturbs negative feedback of PER on its own transcription. Taken together, these in vivo data implicate a central role of CK2α function in timing PER negative feedback in adult circadian neurons. The molecular mechanism that governs organization of physiology and behavior into 24-h rhythms is a conserved transcriptional feedback process that is strikingly similar across distinct phyla. Notably, cyclic phosphorylation of negative feedback regulators is critical to time molecular rhythms. Indeed, mutation of a putative phosphoacceptor site in the human PERIOD2 gene, a key negative regulator, is associated with Advanced Sleep Phase Syndrome. This study reveals a critical role for the protein kinase CK2 for setting the period of behavioral and molecular oscillations in Drosophila. Circadian phenotypes due to CK2 disruption are due to a direct requirement in adult circadian pacemakers. These findings further demonstrate that CK2 modification of the negative feedback regulator PERIOD alters its cyclical phosphorylation, protein abundance, nuclear translocation, and transcriptional repression activity. These studies place CK2 as a central kinase in circadian timing.
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Abstract
This article summarizes the rationale, methods, and results of gene discovery programs in schizophrenia research and describes functional methods of investigating potential candidate genes. It focuses next on the most prominent current candidate genes and describes (1) evidence for their association with schizophrenia and research into the function of each gene; (2) investigation of the clinical phenotypes and endophenotypes associated with each gene, at the levels of psychopathologic, neurocognitive, electrophysiologic, neuroimaging, and neuropathologic findings; and (3) research into the ethologic, cognitive, social, and psychopharmacologic phenotype of mutants with targeted deletion of each gene. It examines gene-gene and gene-environment interactions. Finally, it looks at future directions for research.
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Reilly DF, Westgate EJ, FitzGerald GA. Peripheral Circadian Clocks in the Vasculature. Arterioscler Thromb Vasc Biol 2007; 27:1694-705. [PMID: 17541024 DOI: 10.1161/atvbaha.107.144923] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Living organisms have adapted to the daily rotation of the earth and regular changes in the light environment. Life forms anticipate environmental transitions, adapt their own physiology, and perform activities at behaviorally advantageous times during the day. This is achieved by means of endogenous circadian clocks that can be synchronized to the daily changes in external cues, most notably light and temperature. For many years it was thought that neurons of the suprachiasmatic nucleus (SCN) uniquely controlled circadian rhythmicity of peripheral tissues via neural and humoral signals. The cloning and characterization of mammalian clock genes revealed that they are expressed in a circadian manner throughout the body. It is now accepted that peripheral cells, including those of the cardiovascular system, contain a circadian clock similar to that in the SCN. Many aspects of cardiovascular physiology are subject to diurnal variation, and serious adverse cardiovascular events including myocardial infarction, sudden cardiac death, and stroke occur with a frequency conditioned by time of day. This has raised the possibility that biological responses under the control of the molecular clock might interact with environmental cues to influence the phenotype of human cardiovascular disease.
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Affiliation(s)
- Dermot F Reilly
- Institute for Translational Medicine and Therapeutics, 153 Johnson Pavilion, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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