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Smyllie NJ, Hastings MH, Patton AP. Neuron-Astrocyte Interactions and Circadian Timekeeping in Mammals. Neuroscientist 2024:10738584241245307. [PMID: 38602223 DOI: 10.1177/10738584241245307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Almost every facet of our behavior and physiology varies predictably over the course of day and night, anticipating and adapting us to their associated opportunities and challenges. These rhythms are driven by endogenous biological clocks that, when deprived of environmental cues, can continue to oscillate within a period of approximately 1 day, hence circa-dian. Normally, retinal signals synchronize them to the cycle of light and darkness, but disruption of circadian organization, a common feature of modern lifestyles, carries considerable costs to health. Circadian timekeeping pivots around a cell-autonomous molecular clock, widely expressed across tissues. These cellular timers are in turn synchronized by the principal circadian clock of the brain: the hypothalamic suprachiasmatic nucleus (SCN). Intercellular signals make the SCN network a very powerful pacemaker. Previously, neurons were considered the sole SCN timekeepers, with glial cells playing supportive roles. New discoveries have revealed, however, that astrocytes are active partners in SCN network timekeeping, with their cell-autonomous clock regulating extracellular glutamate and GABA concentrations to control circadian cycles of SCN neuronal activity. Here, we introduce circadian timekeeping at the cellular and SCN network levels before focusing on the contributions of astrocytes and their mutual interaction with neurons in circadian control in the brain.
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Affiliation(s)
- Nicola J Smyllie
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | | | - Andrew P Patton
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
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2
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Wu Q, Ren Q, Wang X, Bai H, Tian D, Gao G, Wang F, Yu P, Chang Y. Cellular iron depletion enhances behavioral rhythm by limiting brain Per1 expression in mice. CNS Neurosci Ther 2024; 30:e14592. [PMID: 38385622 PMCID: PMC10883092 DOI: 10.1111/cns.14592] [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] [Received: 02/15/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 02/23/2024] Open
Abstract
AIMS Disturbances in the circadian rhythm are positively correlated with the processes of aging and related neurodegenerative diseases, which are also associated with brain iron accumulation. However, the role of brain iron in regulating the biological rhythm is poorly understood. In this study, we investigated the impact of brain iron levels on the spontaneous locomotor activity of mice with altered brain iron levels and further explored the potential mechanisms governing these effects in vitro. RESULTS Our results revealed that conditional knockout of ferroportin 1 (Fpn1) in cerebral microvascular endothelial cells led to brain iron deficiency, subsequently resulting in enhanced locomotor activity and increased expression of clock genes, including the circadian locomotor output cycles kaput protein (Clock) and brain and muscle ARNT-like 1 (Bmal1). Concomitantly, the levels of period circadian regulator 1 (PER1), which functions as a transcriptional repressor in regulating biological rhythm, were decreased. Conversely, the elevated brain iron levels in APP/PS1 mice inhibited autonomous rhythmic activity. Additionally, our findings demonstrate a significant decrease in serum melatonin levels in Fpn1cdh5 -CKO mice compared with the Fpn1flox/flox group. In contrast, APP/PS1 mice with brain iron deposition exhibited higher serum melatonin levels than the WT group. Furthermore, in the human glioma cell line, U251, we observed reduced PER1 expression upon iron limitation by deferoxamine (DFO; iron chelator) or endogenous overexpression of FPN1. When U251 cells were made iron-replete by supplementation with ferric ammonium citrate (FAC) or increased iron import through transferrin receptor 1 (TfR1) overexpression, PER1 protein levels were increased. Additionally, we obtained similar results to U251 cells in mouse cerebellar astrocytes (MA-c), where we collected cells at different time points to investigate the rhythmic expression of core clock genes and the impact of DFO or FAC treatment on PER1 protein levels. CONCLUSION These findings collectively suggest that altered iron levels influence the circadian rhythm by regulating PER1 expression and thereby modulating the molecular circadian clock. In conclusion, our study identifies the regulation of brain iron levels as a potential new target for treating age-related disruptions in the circadian rhythm.
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Affiliation(s)
- Qiong Wu
- Laboratory of Molecular Iron Metabolism, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, Hebei Collaborative Innovation Center for Eco‐Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life SciencesHebei Normal UniversityShijiazhuangChina
- Hebei Key Laboratory of Chinese Medicine Research on Cardio‐Cerebrovascular Disease, College of Basic MedicineHebei University of Chinese MedicineShijiazhuangHebei ProvinceChina
| | - Qiuyang Ren
- Laboratory of Molecular Iron Metabolism, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, Hebei Collaborative Innovation Center for Eco‐Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life SciencesHebei Normal UniversityShijiazhuangChina
| | - Xin Wang
- Laboratory of Molecular Iron Metabolism, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, Hebei Collaborative Innovation Center for Eco‐Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life SciencesHebei Normal UniversityShijiazhuangChina
| | - Huiyuan Bai
- Laboratory of Molecular Iron Metabolism, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, Hebei Collaborative Innovation Center for Eco‐Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life SciencesHebei Normal UniversityShijiazhuangChina
| | - Dandan Tian
- Laboratory of Molecular Iron Metabolism, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, Hebei Collaborative Innovation Center for Eco‐Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life SciencesHebei Normal UniversityShijiazhuangChina
| | - Guofen Gao
- Laboratory of Molecular Iron Metabolism, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, Hebei Collaborative Innovation Center for Eco‐Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life SciencesHebei Normal UniversityShijiazhuangChina
| | - Fudi Wang
- School of Public HealthZhejiang University School of MedicineHangzhouZhejiangChina
| | - Peng Yu
- Laboratory of Molecular Iron Metabolism, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, Hebei Collaborative Innovation Center for Eco‐Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life SciencesHebei Normal UniversityShijiazhuangChina
| | - Yan‐Zhong Chang
- Laboratory of Molecular Iron Metabolism, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, Hebei Collaborative Innovation Center for Eco‐Environment, Hebei Research Center of the Basic Discipline of Cell Biology, College of Life SciencesHebei Normal UniversityShijiazhuangChina
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3
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Xie P, Xie X, Ye C, Dean KM, Laothamatas I, Taufique SKT, Takahashi J, Yamazaki S, Xu Y, Liu Y. Mammalian circadian clock proteins form dynamic interacting microbodies distinct from phase separation. Proc Natl Acad Sci U S A 2023; 120:e2318274120. [PMID: 38127982 PMCID: PMC10756265 DOI: 10.1073/pnas.2318274120] [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: 10/28/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) underlies diverse biological processes. Because most LLPS studies were performed in vitro using recombinant proteins or in cells that overexpress protein, the physiological relevance of LLPS for endogenous protein is often unclear. PERIOD, the intrinsically disordered domain-rich proteins, are central mammalian circadian clock components and interact with other clock proteins in the core circadian negative feedback loop. Different core clock proteins were previously shown to form large complexes. Circadian clock studies often rely on experiments that overexpress clock proteins. Here, we show that when Per2 transgene was stably expressed in cells, PER2 protein formed nuclear phosphorylation-dependent slow-moving LLPS condensates that recruited other clock proteins. Super-resolution microscopy of endogenous PER2, however, revealed formation of circadian-controlled, rapidly diffusing nuclear microbodies that were resistant to protein concentration changes, hexanediol treatment, and loss of phosphorylation, indicating that they are distinct from the LLPS condensates caused by protein overexpression. Surprisingly, only a small fraction of endogenous PER2 microbodies transiently interact with endogenous BMAL1 and CRY1, a conclusion that was confirmed in cells and in mice tissues, suggesting an enzyme-like mechanism in the circadian negative feedback process. Together, these results demonstrate that the dynamic interactions of core clock proteins are a key feature of mammalian circadian clock mechanism and the importance of examining endogenous proteins in LLPS and circadian clock studies.
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Affiliation(s)
- Pancheng Xie
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX75390
- Cambridge-Su Genomic Resource Center, Soochow University, Suzhou, Jiangsu215123, China
| | - Xiaowen Xie
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Congrong Ye
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Kevin M. Dean
- Lyda Hill Department of Bioinformatics and Cecil H. and Ida Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Isara Laothamatas
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
| | - S. K. Tahajjul Taufique
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
- Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
| | - Joseph Takahashi
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
| | - Shin Yamazaki
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
- Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
| | - Ying Xu
- Cambridge-Su Genomic Resource Center, Soochow University, Suzhou, Jiangsu215123, China
| | - Yi Liu
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX75390
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4
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Xie P, Xie X, Ye C, Dean KM, Laothamatas I, Taufique SKT, Takahashi J, Yamazaki S, Xu Y, Liu Y. Mammalian circadian clock proteins form dynamic interacting microbodies distinct from phase separation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.19.563153. [PMID: 37961341 PMCID: PMC10634710 DOI: 10.1101/2023.10.19.563153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Liquid-liquid phase separation (LLPS) underlies diverse biological processes. Because most LLPS studies were performed in vitro or in cells that overexpress protein, the physiological relevance of LLPS is unclear. PERIOD proteins are central mammalian circadian clock components and interact with other clock proteins in the core circadian negative feedback loop. Different core clock proteins were previously shown to form large complexes. Here we show that when transgene was stably expressed, PER2 formed nuclear phosphorylation-dependent LLPS condensates that recruited other clock proteins. Super-resolution microscopy of endogenous PER2, however, revealed formation of circadian-controlled, rapidly diffusing microbodies that were resistant to protein concentration changes, hexanediol treatment, and loss of phosphorylation, indicating that they are distinct from the LLPS condensates caused by overexpression. Surprisingly, only a small fraction of endogenous PER2 microbodies transiently interact with endogenous BMAL1 and CRY1, a conclusion that was confirmed in cells and in mice tissues, suggesting an enzyme-like mechanism in the circadian negative feedback process. Together, these results demonstrate that the dynamic interactions of core clock proteins is a key feature of mammalian circadian clock mechanism and the importance of examining endogenous proteins in LLPS and circadian studies.
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Affiliation(s)
- Pancheng Xie
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Cambridge-Su Genomic Resource Center, Soochow University; Suzhou, Jiangsu 215123, China
| | - Xiaowen Xie
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Congrong Ye
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kevin M. Dean
- Lyda Hill Department of Bioinformatics and Cecil H. and Ida Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Isara Laothamatas
- Department of Neuroscience and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9111, USA
| | - S K Tahajjul Taufique
- Department of Neuroscience and Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9111, USA
| | - Joseph Takahashi
- Department of Neuroscience and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9111, USA
| | - Shin Yamazaki
- Department of Neuroscience and Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9111, USA
| | - Ying Xu
- Cambridge-Su Genomic Resource Center, Soochow University; Suzhou, Jiangsu 215123, China
| | - Yi Liu
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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5
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Abenza JF, Rossetti L, Mouelhi M, Burgués J, Andreu I, Kennedy K, Roca-Cusachs P, Marco S, García-Ojalvo J, Trepat X. Mechanical control of the mammalian circadian clock via YAP/TAZ and TEAD. J Cell Biol 2023; 222:e202209120. [PMID: 37378613 PMCID: PMC10308087 DOI: 10.1083/jcb.202209120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 04/13/2023] [Accepted: 05/30/2023] [Indexed: 06/29/2023] Open
Abstract
Autonomous circadian clocks exist in nearly every mammalian cell type. These cellular clocks are subjected to a multilayered regulation sensitive to the mechanochemical cell microenvironment. Whereas the biochemical signaling that controls the cellular circadian clock is increasingly well understood, mechanisms underlying regulation by mechanical cues are largely unknown. Here we show that the fibroblast circadian clock is mechanically regulated through YAP/TAZ nuclear levels. We use high-throughput analysis of single-cell circadian rhythms and apply controlled mechanical, biochemical, and genetic perturbations to study the expression of the clock gene Rev-erbα. We observe that Rev-erbα circadian oscillations are disrupted with YAP/TAZ nuclear translocation. By targeted mutations and overexpression of YAP/TAZ, we show that this mechanobiological regulation, which also impacts core components of the clock such as Bmal1 and Cry1, depends on the binding of YAP/TAZ to the transcriptional effector TEAD. This mechanism could explain the impairment of circadian rhythms observed when YAP/TAZ activity is upregulated, as in cancer and aging.
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Affiliation(s)
- Juan F. Abenza
- Institute for Bioengineering of Catalonia, The Barcelona Institute for Science and Technology, Barcelona, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain
| | - Leone Rossetti
- Institute for Bioengineering of Catalonia, The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Malèke Mouelhi
- Institute for Bioengineering of Catalonia, The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Javier Burgués
- Institute for Bioengineering of Catalonia, The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Ion Andreu
- Institute for Bioengineering of Catalonia, The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Keith Kennedy
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Pere Roca-Cusachs
- Institute for Bioengineering of Catalonia, The Barcelona Institute for Science and Technology, Barcelona, Spain
- Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain
| | - Santiago Marco
- Institute for Bioengineering of Catalonia, The Barcelona Institute for Science and Technology, Barcelona, Spain
- Department of Electronics and Biomedical Engineering, Universitat de Barcelona, Barcelona, Spain
| | - Jordi García-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Xavier Trepat
- Institute for Bioengineering of Catalonia, The Barcelona Institute for Science and Technology, Barcelona, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain
- Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
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Zhang L, Malkemper EP. Cryptochromes in mammals: a magnetoreception misconception? Front Physiol 2023; 14:1250798. [PMID: 37670767 PMCID: PMC10475740 DOI: 10.3389/fphys.2023.1250798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 08/01/2023] [Indexed: 09/07/2023] Open
Abstract
Cryptochromes are flavoproteins related to photolyases that are widespread throughout the plant and animal kingdom. They govern blue light-dependent growth in plants, control circadian rhythms in a light-dependent manner in invertebrates, and play a central part in the circadian clock in vertebrates. In addition, cryptochromes might function as receptors that allow animals to sense the Earth's magnetic field. As cryptochromes are also present in mammals including humans, the possibility of a magnetosensitive protein is exciting. Here we attempt to provide a concise overview of cryptochromes in mammals. We briefly review their canonical role in the circadian rhythm from the molecular level to physiology, behaviour and diseases. We then discuss their disputed light sensitivity and proposed role in the magnetic sense in mammals, providing three mechanistic hypotheses. Specifically, mammalian cryptochromes could form light-induced radical pairs in particular cellular milieus, act as magnetoreceptors in darkness, or as secondary players in a magnetoreception signalling cascade. Future research can test these hypotheses to investigate if the role of mammalian cryptochromes extends beyond the circadian clock.
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Affiliation(s)
| | - E. Pascal Malkemper
- Max Planck Research Group Neurobiology of Magnetoreception, Max Planck Institute for Neurobiology of Behavior—caesar, Bonn, Germany
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7
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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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8
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Patton AP, Morris EL, McManus D, Wang H, Li Y, Chin JW, Hastings MH. Astrocytic control of extracellular GABA drives circadian timekeeping in the suprachiasmatic nucleus. Proc Natl Acad Sci U S A 2023; 120:e2301330120. [PMID: 37186824 PMCID: PMC10214171 DOI: 10.1073/pnas.2301330120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 04/12/2023] [Indexed: 05/17/2023] Open
Abstract
The hypothalamic suprachiasmatic nucleus (SCN) is the master mammalian circadian clock. Its cell-autonomous timing mechanism, a transcriptional/translational feedback loop (TTFL), drives daily peaks of neuronal electrical activity, which in turn control circadian behavior. Intercellular signals, mediated by neuropeptides, synchronize and amplify TTFL and electrical rhythms across the circuit. SCN neurons are GABAergic, but the role of GABA in circuit-level timekeeping is unclear. How can a GABAergic circuit sustain circadian cycles of electrical activity, when such increased neuronal firing should become inhibitory to the network? To explore this paradox, we show that SCN slices expressing the GABA sensor iGABASnFR demonstrate a circadian oscillation of extracellular GABA ([GABA]e) that, counterintuitively, runs in antiphase to neuronal activity, with a prolonged peak in circadian night and a pronounced trough in circadian day. Resolving this unexpected relationship, we found that [GABA]e is regulated by GABA transporters (GATs), with uptake peaking during circadian day, hence the daytime trough and nighttime peak. This uptake is mediated by the astrocytically expressed transporter GAT3 (Slc6a11), expression of which is circadian-regulated, being elevated in daytime. Clearance of [GABA]e in circadian day facilitates neuronal firing and is necessary for circadian release of the neuropeptide vasoactive intestinal peptide, a critical regulator of TTFL and circuit-level rhythmicity. Finally, we show that genetic complementation of the astrocytic TTFL alone, in otherwise clockless SCN, is sufficient to drive [GABA]e rhythms and control network timekeeping. Thus, astrocytic clocks maintain the SCN circadian clockwork by temporally controlling GABAergic inhibition of SCN neurons.
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Affiliation(s)
- Andrew P. Patton
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Emma L. Morris
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - David McManus
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Huan Wang
- State Key Laboratory of Membrane Biology, Peking University, School of Life Sciences, 100871Beijing, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University, School of Life Sciences, 100871Beijing, China
| | - Jason W. Chin
- PNAC Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Michael H. Hastings
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
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9
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Zhang J, Li S, Luo X, Zhang C. Emerging role of hypothalamus in the metabolic regulation in the offspring of maternal obesity. Front Nutr 2023; 10:1094616. [PMID: 36819678 PMCID: PMC9928869 DOI: 10.3389/fnut.2023.1094616] [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: 11/10/2022] [Accepted: 01/17/2023] [Indexed: 02/04/2023] Open
Abstract
Maternal obesity has a significant impact on the metabolism of offspring both in childhood and adulthood. The metabolic regulation of offspring is influenced by the intrauterine metabolic programming induced by maternal obesity. Nevertheless, the precise mechanisms remain unclear. The hypothalamus is the primary target of metabolic programming and the principal regulatory center of energy metabolism. Accumulating evidence has indicated the crucial role of hypothalamic regulation in the metabolism of offspring exposed to maternal obesity. This article reviews the development of hypothalamus, the role of the hypothalamic regulations in energy homeostasis, possible mechanisms underlying the developmental programming of energy metabolism in offspring, and the potential therapeutic approaches for preventing metabolic diseases later in life. Lastly, we discuss the challenges and future directions of hypothalamic regulation in the metabolism of children born to obese mothers.
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10
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Different Approaches to Study Molecular Blueprint and Biological Behavior of Brain Tumors: Editorial to the Special Issue "Advances in Molecular Genetics of Brain Tumors". Int J Mol Sci 2023; 24:ijms24020948. [PMID: 36674461 PMCID: PMC9865200 DOI: 10.3390/ijms24020948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/18/2022] [Accepted: 12/23/2022] [Indexed: 01/06/2023] Open
Abstract
Cancer remains one of the leading causes of mortality worldwide [...].
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McManus D, Polidarova L, Smyllie NJ, Patton AP, Chesham JE, Maywood ES, Chin JW, Hastings MH. Cryptochrome 1 as a state variable of the circadian clockwork of the suprachiasmatic nucleus: Evidence from translational switching. Proc Natl Acad Sci U S A 2022; 119:e2203563119. [PMID: 35976881 PMCID: PMC9407638 DOI: 10.1073/pnas.2203563119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The suprachiasmatic nucleus (SCN) of the hypothalamus is the principal clock driving circadian rhythms of physiology and behavior that adapt mammals to environmental cycles. Disruption of SCN-dependent rhythms compromises health, and so understanding SCN time keeping will inform management of diseases associated with modern lifestyles. SCN time keeping is a self-sustaining transcriptional/translational delayed feedback loop (TTFL), whereby negative regulators inhibit their own transcription. Formally, the SCN clock is viewed as a limit-cycle oscillator, the simplest being a trajectory of successive phases that progresses through two-dimensional space defined by two state variables mapped along their respective axes. The TTFL motif is readily compatible with limit-cycle models, and in Neurospora and Drosophila the negative regulators Frequency (FRQ) and Period (Per) have been identified as state variables of their respective TTFLs. The identity of state variables of the SCN oscillator is, however, less clear. Experimental identification of state variables requires reversible and temporally specific control over their abundance. Translational switching (ts) provides this, the expression of a protein of interest relying on the provision of a noncanonical amino acid. We show that the negative regulator Cryptochrome 1 (CRY1) fulfills criteria defining a state variable: ts-CRY1 dose-dependently and reversibly suppresses the baseline, amplitude, and period of SCN rhythms, and its acute withdrawal releases the TTFL to oscillate from a defined phase. Its effect also depends on its temporal pattern of expression, although constitutive ts-CRY1 sustained (albeit less stable) oscillations. We conclude that CRY1 has properties of a state variable, but may operate among several state variables within a multidimensional limit cycle.
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Affiliation(s)
- David McManus
- aNeurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Lenka Polidarova
- aNeurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Nicola J. Smyllie
- aNeurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Andrew P. Patton
- aNeurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Johanna E. Chesham
- aNeurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Elizabeth S. Maywood
- aNeurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Jason W. Chin
- bPNAC Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Michael H. Hastings
- aNeurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
- 1To whom correspondence may be addressed.
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The duper mutation reveals previously unsuspected functions of Cryptochrome 1 in circadian entrainment and heart disease. Proc Natl Acad Sci U S A 2022; 119:e2121883119. [PMID: 35930669 PMCID: PMC9371649 DOI: 10.1073/pnas.2121883119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The Cryptochrome 1 (Cry1)-deficient duper mutant hamster has a short free-running period in constant darkness (τDD) and shows large phase shifts in response to brief light pulses. We tested whether this measure of the lability of the circadian phase is a general characteristic of Cry1-null animals and whether it indicates resistance to jet lag. Upon advance of the light:dark (LD) cycle, both duper hamsters and Cry1-/- mice re-entrained locomotor rhythms three times as fast as wild types. However, accelerated re-entrainment was dissociated from the amplified phase-response curve (PRC): unlike duper hamsters, Cry1-/- mice show no amplification of the phase response to 15' light pulses. Neither the amplified acute shifts nor the increased rate of re-entrainment in duper mutants is due to acceleration of the circadian clock: when mutants drank heavy water to lengthen the period, these aspects of the phenotype persisted. In light of the health consequences of circadian misalignment, we examined effects of duper and phase shifts on a hamster model of heart disease previously shown to be aggravated by repeated phase shifts. The mutation shortened the lifespan of cardiomyopathic hamsters relative to wild types, but this effect was eliminated when mutants experienced 8-h phase shifts every second week, to which they rapidly re-entrained. Our results reveal previously unsuspected roles of Cry1 in phase shifting and longevity in the face of heart disease. The duper mutant offers new opportunities to understand the basis of circadian disruption and jet lag.
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Patton AP, Smyllie NJ, Chesham JE, Hastings MH. Astrocytes Sustain Circadian Oscillation and Bidirectionally Determine Circadian Period, But Do Not Regulate Circadian Phase in the Suprachiasmatic Nucleus. J Neurosci 2022; 42:5522-5537. [PMID: 35610047 PMCID: PMC9295834 DOI: 10.1523/jneurosci.2337-21.2022] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 03/20/2022] [Accepted: 05/03/2022] [Indexed: 11/21/2022] Open
Abstract
The suprachiasmatic nucleus (SCN) is the master circadian clock of mammals, generating and transmitting an internal representation of environmental time that is produced by the cell-autonomous transcriptional/post-translational feedback loops (TTFLs) of the 10,000 neurons and 3500 glial cells. Recently, we showed that TTFL function in SCN astrocytes alone is sufficient to drive circadian timekeeping and behavior, raising questions about the respective contributions of astrocytes and neurons within the SCN circuit. We compared their relative roles in circadian timekeeping in mouse SCN explants, of either sex. Treatment with the glial-specific toxin fluorocitrate revealed a requirement for metabolically competent astrocytes for circuit-level timekeeping. Recombinase-mediated genetically complemented Cryptochrome (Cry) proteins in Cry1-deficient and/or Cry2-deficient SCNs were used to compare the influence of the TTFLs of neurons or astrocytes in the initiation of de novo oscillation or in pacemaking. While neurons and astrocytes both initiated de novo oscillation and lengthened the period equally, their kinetics were different, with astrocytes taking twice as long. Furthermore, astrocytes could shorten the period, but not as potently as neurons. Chemogenetic manipulation of Gi- and Gq-coupled signaling pathways in neurons acutely advanced or delayed the ensemble phase, respectively. In contrast, comparable manipulations in astrocytes were without effect. Thus, astrocytes can initiate SCN rhythms and bidirectionally control the SCN period, albeit with lower potency than neurons. Nevertheless, their activation does not influence the SCN phase. The emergent SCN properties of high-amplitude oscillation, initiation of rhythmicity, pacemaking, and phase are differentially regulated: astrocytes and neurons sustain the ongoing oscillation, but its phase is determined by neurons.SIGNIFICANCE STATEMENT The hypothalamic suprachiasmatic nucleus (SCN) encodes and disseminates time-of-day information to allow mammals to adapt their physiology to daily environmental cycles. Recent investigations have revealed a role for astrocytes, in addition to neurons, in the regulation of this rhythm. Using pharmacology, genetic complementation, and chemogenetics, we compared the abilities of neurons and astrocytes in determining the emergent SCN properties of high-amplitude oscillation, initiation of rhythmicity, pacemaking, and determination of phase. These findings parameterize the circadian properties of the astrocyte population in the SCN and reveal the types of circadian information that astrocytes and neurons can contribute within their heterogeneous cellular network.
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Affiliation(s)
- Andrew P Patton
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Nicola J Smyllie
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Johanna E Chesham
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
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Koch AA, Bagnall JS, Smyllie NJ, Begley N, Adamson AD, Fribourgh JL, Spiller DG, Meng QJ, Partch CL, Strimmer K, House TA, Hastings MH, Loudon ASI. Quantification of protein abundance and interaction defines a mechanism for operation of the circadian clock. eLife 2022; 11:73976. [PMID: 35285799 PMCID: PMC8983044 DOI: 10.7554/elife.73976] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 03/11/2022] [Indexed: 11/13/2022] Open
Abstract
The mammalian circadian clock exerts control of daily gene expression through cycles of DNA binding. Here, we develop a quantitative model of how a finite pool of BMAL1 protein can regulate thousands of target sites over daily time scales. We used quantitative imaging to track dynamic changes in endogenous labelled proteins across peripheral tissues and the SCN. We determine the contribution of multiple rhythmic processes coordinating BMAL1 DNA binding, including cycling molecular abundance, binding affinities, and repression. We find nuclear BMAL1 concentration determines corresponding CLOCK through heterodimerisation and define a DNA residence time of this complex. Repression of CLOCK:BMAL1 is achieved through rhythmic changes to BMAL1:CRY1 association and high-affinity interactions between PER2:CRY1 which mediates CLOCK:BMAL1 displacement from DNA. Finally, stochastic modelling reveals a dual role for PER:CRY complexes in which increasing concentrations of PER2:CRY1 promotes removal of BMAL1:CLOCK from genes consequently enhancing ability to move to new target sites.
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Affiliation(s)
- Alex Ashton Koch
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - James S Bagnall
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Nicola J Smyllie
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, United Kingdom
| | - Nicola Begley
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Antony D Adamson
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Jennifer L Fribourgh
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, United States
| | - David G Spiller
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Qing-Jun Meng
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Carrie L Partch
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, United States
| | - Korbinian Strimmer
- Department of Mathematics, University of Manchester, Manchester, United Kingdom
| | - Thomas A House
- Department of Mathematics, University of Manchester, Manchester, United Kingdom
| | - Michael H Hastings
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, United Kingdom
| | - Andrew S I Loudon
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
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