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Buller S, Blouet C. Brain access of incretins and incretin receptor agonists to their central targets relevant for appetite suppression and weight loss. Am J Physiol Endocrinol Metab 2024; 326:E472-E480. [PMID: 38381398 DOI: 10.1152/ajpendo.00250.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 01/05/2024] [Accepted: 02/13/2024] [Indexed: 02/22/2024]
Abstract
New incretin-based pharmacotherapies provide efficient and safe therapeutic options to curb appetite and produce weight loss in patients with obesity. Delivered systemically, these molecules produce pleiotropic metabolic benefits, but the target sites mediating their weight-suppressive action are located within the brain. Recent research has increased our understanding of the neural circuits and behavioral mechanisms involved in the anorectic and metabolic consequences of glucagon-like peptide 1 (GLP-1)-based weight loss strategies, yet little is known about how these drugs access their functional targets in the brain to produce sustained weight loss. The majority of brain cells expressing incretin receptors are located behind the blood-brain barrier, shielded from the circulation and fluctuations in the availability of peripheral signals, which is a major challenge for the development of CNS-targeted therapeutic peptides. GLP-1 receptor (GLP-1R) agonists with increased half-life and enhanced therapeutic benefit do not cross the blood-brain barrier, yet they manage to access discrete brain sites relevant to the regulation of energy homeostasis. In this review, we give a brief overview of the different routes for peptide hormones to access the brain. We then examine the evidence informing the routes employed by incretins and incretin receptor agonists to access brain targets relevant for their appetite and weight-suppressive actions. We highlight existing controversies and suggest future directions to further establish the functionally relevant access routes for GLP-1-based weight loss compounds, which might guide the development and selection of the future generation of incretin receptor polypharmacologies.
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Affiliation(s)
- Sophie Buller
- Medical Research Council (MRC) Metabolic Diseases Unit, Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Clemence Blouet
- Medical Research Council (MRC) Metabolic Diseases Unit, Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
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2
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Brüning JC, Fenselau H. Integrative neurocircuits that control metabolism and food intake. Science 2023; 381:eabl7398. [PMID: 37769095 DOI: 10.1126/science.abl7398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 08/31/2023] [Indexed: 09/30/2023]
Abstract
Systemic metabolism has to be constantly adjusted to the variance of food intake and even be prepared for anticipated changes in nutrient availability. Therefore, the brain integrates multiple homeostatic signals with numerous cues that predict future deviations in energy supply. Recently, our understanding of the neural pathways underlying these regulatory principles-as well as their convergence in the hypothalamus as the key coordinator of food intake, energy expenditure, and glucose metabolism-have been revealed. These advances have changed our view of brain-dependent control of metabolic physiology. In this Review, we discuss new concepts about how alterations in these pathways contribute to the development of prevalent metabolic diseases such as obesity and type 2 diabetes mellitus and how this emerging knowledge may provide new targets for their treatment.
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Affiliation(s)
- Jens C Brüning
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
- National Center for Diabetes Research (DZD), 85764 Neuherberg, Germany
| | - Henning Fenselau
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
- Research Group Synaptic Transmission in Energy Homeostasis, Max Planck Institute for Metabolism Research, 50931 Cologne, Germany
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3
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Gogiraju R, Witzler C, Shahneh F, Hubert A, Renner L, Bochenek ML, Zifkos K, Becker C, Thati M, Schäfer K. Deletion of endothelial leptin receptors in mice promotes diet-induced obesity. Sci Rep 2023; 13:8276. [PMID: 37217565 DOI: 10.1038/s41598-023-35281-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 05/16/2023] [Indexed: 05/24/2023] Open
Abstract
Obesity promotes endothelial dysfunction. Endothelial cells not only respond, but possibly actively promote the development of obesity and metabolic dysfunction. Our aim was to characterize the role of endothelial leptin receptors (LepR) for endothelial and whole body metabolism and diet-induced obesity. Mice with tamoxifen-inducible, Tie2.Cre-ERT2-mediated deletion of LepR in endothelial cells (End.LepR knockout, KO) were fed high-fat diet (HFD) for 16 weeks. Body weight gain, serum leptin levels, visceral adiposity and adipose tissue inflammation were more pronounced in obese End.LepR-KO mice, whereas fasting serum glucose and insulin levels or the extent of hepatic steatosis did not differ. Reduced brain endothelial transcytosis of exogenous leptin, increased food intake and total energy balance were observed in End.LepR-KO mice and accompanied by brain perivascular macrophage accumulation, whereas physical activity, energy expenditure and respiratory exchange rates did not differ. Metabolic flux analysis revealed no changes in the bioenergetic profile of endothelial cells from brain or visceral adipose tissue, but higher glycolysis and mitochondrial respiration rates in those isolated from lungs. Our findings support a role for endothelial LepRs in the transport of leptin into the brain and neuronal control of food intake, and also suggest organ-specific changes in endothelial cell, but not whole-body metabolism.
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Affiliation(s)
- Rajinikanth Gogiraju
- Department of Cardiology, Cardiology I, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Claudius Witzler
- Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany
| | - Fatemeh Shahneh
- Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany
| | - Astrid Hubert
- Department of Cardiology, Cardiology I, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Luisa Renner
- Department of Cardiology, Cardiology I, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Magdalena L Bochenek
- Department of Cardiology, Cardiology I, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
- Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany
| | - Konstantinos Zifkos
- Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany
| | - Christian Becker
- Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany
- Clinic of Dermatology, University Clinic Münster, Münster, Germany
| | - Madhusudhan Thati
- Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany
| | - Katrin Schäfer
- Department of Cardiology, Cardiology I, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.
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Dali R, Estrada-Meza J, Langlet F. Tanycyte, the neuron whisperer. Physiol Behav 2023; 263:114108. [PMID: 36740135 DOI: 10.1016/j.physbeh.2023.114108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 01/23/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023]
Abstract
Reciprocal communication between neurons and glia is essential for normal brain functioning and adequate physiological functions, including energy balance. In vertebrates, the homeostatic process that adjusts food intake and energy expenditure in line with physiological requirements is tightly controlled by numerous neural cell types located within the hypothalamus and the brainstem and organized in complex networks. Within these neural networks, peculiar ependymoglial cells called tanycytes are nowadays recognized as multifunctional players in the physiological mechanisms of appetite control, partly by modulating orexigenic and anorexigenic neurons. Here, we review recent advances in tanycytes' impact on hypothalamic neuronal activity, emphasizing on arcuate neurons.
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Affiliation(s)
- Rafik Dali
- Department of biomedical sciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Judith Estrada-Meza
- Department of biomedical sciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Fanny Langlet
- Department of biomedical sciences, University of Lausanne, 1005 Lausanne, Switzerland.
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Recent Advances in the Knowledge of the Mechanisms of Leptin Physiology and Actions in Neurological and Metabolic Pathologies. Int J Mol Sci 2023; 24:ijms24021422. [PMID: 36674935 PMCID: PMC9860943 DOI: 10.3390/ijms24021422] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/05/2023] [Accepted: 01/07/2023] [Indexed: 01/13/2023] Open
Abstract
Excess body weight is frequently associated with low-grade inflammation. Evidence indicates a relationship between obesity and cancer, as well as with other diseases, such as diabetes and non-alcoholic fatty liver disease, in which inflammation and the actions of various adipokines play a role in the pathological mechanisms involved in these disorders. Leptin is mainly produced by adipose tissue in proportion to fat stores, but it is also synthesized in other organs, where leptin receptors are expressed. This hormone performs numerous actions in the brain, mainly related to the control of energy homeostasis. It is also involved in neurogenesis and neuroprotection, and central leptin resistance is related to some neurological disorders, e.g., Parkinson's and Alzheimer's diseases. In peripheral tissues, leptin is implicated in the regulation of metabolism, as well as of bone density and muscle mass. All these actions can be affected by changes in leptin levels and the mechanisms associated with resistance to this hormone. This review will present recent advances in the molecular mechanisms of leptin action and their underlying roles in pathological situations, which may be of interest for revealing new approaches for the treatment of diseases where the actions of this adipokine might be compromised.
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Kim DW, Tu KJ, Wei A, Lau AJ, Gonzalez-Gil A, Cao T, Braunstein K, Ling JP, Troncoso JC, Wong PC, Blackshaw S, Schnaar RL, Li T. Amyloid-beta and tau pathologies act synergistically to induce novel disease stage-specific microglia subtypes. Mol Neurodegener 2022; 17:83. [PMID: 36536457 PMCID: PMC9762062 DOI: 10.1186/s13024-022-00589-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Amongst risk alleles associated with late-onset Alzheimer's disease (AD), those that converged on the regulation of microglia activity have emerged as central to disease progression. Yet, how canonical amyloid-β (Aβ) and tau pathologies regulate microglia subtypes during the progression of AD remains poorly understood. METHODS We use single-cell RNA-sequencing to profile microglia subtypes from mice exhibiting both Aβ and tau pathologies across disease progression. We identify novel microglia subtypes that are induced in response to both Aβ and tau pathologies in a disease-stage-specific manner. To validate the observation in AD mouse models, we also generated a snRNA-Seq dataset from the human superior frontal gyrus (SFG) and entorhinal cortex (ERC) at different Braak stages. RESULTS We show that during early-stage disease, interferon signaling induces a subtype of microglia termed Early-stage AD-Associated Microglia (EADAM) in response to both Aβ and tau pathologies. During late-stage disease, a second microglia subtype termed Late-stage AD-Associated Microglia (LADAM) is detected. While similar microglia subtypes are observed in other models of neurodegenerative disease, the magnitude and composition of gene signatures found in EADAM and LADAM are distinct, suggesting the necessity of both Aβ and tau pathologies to elicit their emergence. Importantly, the pattern of EADAM- and LADAM-associated gene expression is observed in microglia from AD brains, during the early (Braak II)- or late (Braak VI/V)- stage of the disease, respectively. Furthermore, we show that several Siglec genes are selectively expressed in either EADAM or LADAM. Siglecg is expressed in white-matter-associated LADAM, and expression of Siglec-10, the human orthologue of Siglecg, is progressively elevated in an AD-stage-dependent manner but not shown in non-AD tauopathy. CONCLUSIONS Using scRNA-Seq in mouse models bearing amyloid-β and/or tau pathologies, we identify novel microglia subtypes induced by the combination of Aβ and tau pathologies in a disease stage-specific manner. Our findings suggest that both Aβ and tau pathologies are required for the disease stage-specific induction of EADAM and LADAM. In addition, we revealed Siglecs as biomarkers of AD progression and potential therapeutic targets.
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Affiliation(s)
- Dong Won Kim
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Kevin J. Tu
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Alice Wei
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Ashley J. Lau
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Anabel Gonzalez-Gil
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Tianyu Cao
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Kerstin Braunstein
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Jonathan P. Ling
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Juan C. Troncoso
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Philip C. Wong
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Ronald L. Schnaar
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Tong Li
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
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Nampoothiri S, Nogueiras R, Schwaninger M, Prevot V. Glial cells as integrators of peripheral and central signals in the regulation of energy homeostasis. Nat Metab 2022; 4:813-825. [PMID: 35879459 PMCID: PMC7613794 DOI: 10.1038/s42255-022-00610-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 06/15/2022] [Indexed: 01/03/2023]
Abstract
Communication between the periphery and the brain is key for maintaining energy homeostasis. To do so, peripheral signals from the circulation reach the brain via the circumventricular organs (CVOs), which are characterized by fenestrated vessels lacking the protective blood-brain barrier (BBB). Glial cells, by virtue of their plasticity and their ideal location at the interface of blood vessels and neurons, participate in the integration and transmission of peripheral information to neuronal networks in the brain for the neuroendocrine control of whole-body metabolism. Metabolic diseases, such as obesity and type 2 diabetes, can disrupt the brain-to-periphery communication mediated by glial cells, highlighting the relevance of these cell types in the pathophysiology of such complications. An improved understanding of how glial cells integrate and respond to metabolic and humoral signals has become a priority for the discovery of promising therapeutic strategies to treat metabolic disorders. This Review highlights the role of glial cells in the exchange of metabolic signals between the periphery and the brain that are relevant for the regulation of whole-body energy homeostasis.
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Affiliation(s)
- Sreekala Nampoothiri
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
| | - Ruben Nogueiras
- Universidade de Santiago de Compostela-Instituto de Investigation Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatologia de la Obesidad y Nutrition, Santiago de Compostela, Spain
| | - Markus Schwaninger
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
| | - Vincent Prevot
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France.
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8
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Socol CT, Chira A, Martinez-Sanchez MA, Nuñez-Sanchez MA, Maerescu CM, Mierlita D, Rusu AV, Ruiz-Alcaraz AJ, Trif M, Ramos-Molina B. Leptin Signaling in Obesity and Colorectal Cancer. Int J Mol Sci 2022; 23:4713. [PMID: 35563103 PMCID: PMC9102849 DOI: 10.3390/ijms23094713] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/19/2022] [Accepted: 04/22/2022] [Indexed: 12/05/2022] Open
Abstract
Obesity and colorectal cancer (CRC) are among the leading diseases causing deaths in the world, showing a complex multifactorial pathology. Obesity is considered a risk factor in CRC development through inflammation, metabolic, and signaling processes. Leptin is one of the most important adipokines related to obesity and an important proinflammatory marker, mainly expressed in adipose tissue, with many genetic variation profiles, many related influencing factors, and various functions that have been ascribed but not yet fully understood and elucidated, the most important ones being related to energy metabolism, as well as endocrine and immune systems. Aberrant signaling and genetic variations of leptin are correlated with obesity and CRC, with the genetic causality showing both inherited and acquired events, in addition to lifestyle and environmental risk factors; these might also be related to specific pathogenic pathways at different time points. Moreover, mutation gain is a crucial factor enabling the genetic process of CRC. Currently, the inconsistent and insufficient data related to leptin's relationship with obesity and CRC indicate the necessity of further related studies. This review summarizes the current knowledge on leptin genetics and its potential relationship with the main pathogenic pathways of obesity and CRC, in an attempt to understand the molecular mechanisms of these associations, in the context of inconsistent and contradictory data. The understanding of these mechanisms linking obesity and CRC could help to develop novel therapeutic targets and prevention strategies, resulting in a better prognosis and management of these diseases.
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Affiliation(s)
| | - Alexandra Chira
- 2nd Medical Clinic, Department of Internal Medicine, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400006 Cluj-Napoca, Romania;
| | - Maria Antonia Martinez-Sanchez
- Obesity and Metabolism Laboratory, Biomedical Research Institute of Murcia (IMIB), 30120 Murcia, Spain; (M.A.M.-S.); (M.A.N.-S.)
| | - Maria Angeles Nuñez-Sanchez
- Obesity and Metabolism Laboratory, Biomedical Research Institute of Murcia (IMIB), 30120 Murcia, Spain; (M.A.M.-S.); (M.A.N.-S.)
| | | | - Daniel Mierlita
- Department of Nutrition, University of Oradea, 410048 Oradea, Romania;
| | - Alexandru Vasile Rusu
- Life Science Institute, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, 400372 Cluj-Napoca, Romania;
- Faculty of Animal Science and Biotechnology, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, 400372 Cluj-Napoca, Romania
| | - Antonio Jose Ruiz-Alcaraz
- Department of Biochemistry and Molecular B and Immunology, Faculty of Medicine, University of Murcia, 30100 Murcia, Spain;
| | - Monica Trif
- Department of Food Research, Centiv GmbH, 28857 Syke, Germany;
| | - Bruno Ramos-Molina
- Obesity and Metabolism Laboratory, Biomedical Research Institute of Murcia (IMIB), 30120 Murcia, Spain; (M.A.M.-S.); (M.A.N.-S.)
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9
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Jais A, Brüning JC. Arcuate Nucleus-Dependent Regulation of Metabolism-Pathways to Obesity and Diabetes Mellitus. Endocr Rev 2022; 43:314-328. [PMID: 34490882 PMCID: PMC8905335 DOI: 10.1210/endrev/bnab025] [Citation(s) in RCA: 66] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Indexed: 01/12/2023]
Abstract
The central nervous system (CNS) receives information from afferent neurons, circulating hormones, and absorbed nutrients and integrates this information to orchestrate the actions of the neuroendocrine and autonomic nervous systems in maintaining systemic metabolic homeostasis. Particularly the arcuate nucleus of the hypothalamus (ARC) is of pivotal importance for primary sensing of adiposity signals, such as leptin and insulin, and circulating nutrients, such as glucose. Importantly, energy state-sensing neurons in the ARC not only regulate feeding but at the same time control multiple physiological functions, such as glucose homeostasis, blood pressure, and innate immune responses. These findings have defined them as master regulators, which adapt integrative physiology to the energy state of the organism. The disruption of this fine-tuned control leads to an imbalance between energy intake and expenditure as well as deregulation of peripheral metabolism. Improving our understanding of the cellular, molecular, and functional basis of this regulatory principle in the CNS could set the stage for developing novel therapeutic strategies for the treatment of obesity and metabolic syndrome. In this review, we summarize novel insights with a particular emphasis on ARC neurocircuitries regulating food intake and glucose homeostasis and sensing factors that inform the brain of the organismal energy status.
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Affiliation(s)
- Alexander Jais
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany.,Center for Endocrinology, Diabetes and Preventive Medicine (CEDP), University Hospital Cologne, Cologne, Germany.,Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.,Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig and University Hospital Leipzig, Leipzig, Germany
| | - Jens C Brüning
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany.,Center for Endocrinology, Diabetes and Preventive Medicine (CEDP), University Hospital Cologne, Cologne, Germany.,Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.,National Center for Diabetes Research (DZD), Neuherberg, Germany
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10
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Maffei M, Giordano A. Leptin, the brain and energy homeostasis: From an apparently simple to a highly complex neuronal system. Rev Endocr Metab Disord 2022; 23:87-101. [PMID: 33822303 DOI: 10.1007/s11154-021-09636-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/11/2021] [Indexed: 12/14/2022]
Abstract
Leptin, produced and secreted by white adipose tissue in tight relationship with adipose mass, informs the brain about the status of the energy stores serving as the main peripheral signal for energy balance regulation through interaction with a multitude of highly interconnected neuronal populations. Most obese patients display resistance to the anorectic effect of the hormone. The present review unravels the multiple levels of complexity that trigger hypothalamic response to leptin with the objective of highlighting those critical hubs that, mainly in the hypothalamic arcuate nucleus, may undergo obesity-induced alterations and create an obstacle to leptin action. Several mechanisms underlying leptin resistance have been proposed, possibly representing useful targets to empower leptin effects. Among these, a special focus is herein dedicated to detail how leptin gains access into the brain and how neuronal plasticity may interfere with leptin function.
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Affiliation(s)
- Margherita Maffei
- Institute of Clinical Physiology, CNR, Via Moruzzi 1, 56124, Pisa, Italy.
- Obesity and Lipodystrophy Center, University Hospital of Pisa, Via Paradisa 2, 56124, Pisa, Italy.
| | - Antonio Giordano
- Department of Experimental and Clinical Medicine, Marche Polytechnic University, Via Tronto 10/A, 60020, Ancona, Italy.
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11
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Clayton RW, Lovell-Badge R, Galichet C. The Properties and Functions of Glial Cell Types of the Hypothalamic Median Eminence. Front Endocrinol (Lausanne) 2022; 13:953995. [PMID: 35966104 PMCID: PMC9363565 DOI: 10.3389/fendo.2022.953995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 06/17/2022] [Indexed: 02/06/2023] Open
Abstract
The median eminence (ME) is part of the neuroendocrine system (NES) that functions as a crucial interface between the hypothalamus and pituitary gland. The ME contains many non-neuronal cell types, including oligodendrocytes, oligodendrocyte precursor cells (OPCs), tanycytes, astrocytes, pericytes, microglia and other immune cells, which may be involved in the regulation of NES function. For example, in mice, ablation of tanycytes (a special class of ependymal glia with stem cell-like functions) results in weight gain, feeding, insulin insensitivity and increased visceral adipose, consistent with the demonstrated ability of these cells to sense and transport both glucose and leptin, and to differentiate into neurons that control feeding and metabolism in the hypothalamus. To give a further example, OPCs in the ME of mice have been shown to rapidly respond to dietary signals, in turn controlling composition of the extracellular matrix in the ME, derived from oligodendrocyte-lineage cells, which may contribute to the previously described role of these cells in actively maintaining leptin-receptor-expressing dendrites in the ME. In this review, we explore and discuss recent advances such as these, that have developed our understanding of how the various cell types of the ME contribute to its function in the NES as the interface between the hypothalamus and pituitary gland. We also highlight avenues of future research which promise to uncover additional functions of the ME and the glia, stem and progenitor cells it contains.
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12
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Liu Y, Xu YC, Cui YG, Jiang SW, Diao FY, Liu JY, Ma X. Androgen Excess Increases Food Intake in a Rat Polycystic Ovary Syndrome Model by Downregulating Hypothalamus Insulin and Leptin Signaling Pathways Preceding Weight Gain. Neuroendocrinology 2022; 112:966-981. [PMID: 34847556 PMCID: PMC9677863 DOI: 10.1159/000521236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 11/30/2021] [Indexed: 12/04/2022]
Abstract
BACKGROUND Polycystic ovary syndrome (PCOS) is a common reproductive and metabolic disorder characterized by high androgen levels. The aim of this study was to evaluate the effects of hyperandrogenism on the hypothalamus and subsequently on the food intake and obesity in females. METHODS A dihydroxy testosterone (DHT)-induced rat model was established to recapitulate the hyperandrogenism features of PCOS patients. Body weight and food intake of the rats were recorded. The food intake of DHT-induced rats was restricted by pair feeding to exclude possible effects of weight gain on the hypothalamus. The expression levels of relevant proteins and mRNAs in the hypothalamus and primary hypothalamic neurons exposed to DHT were analyzed by Western blotting and RT-PCR, respectively. The leptin levels in the serum and cerebrospinal fluid (CSF) were measured, and leptin was injected via the intracerebroventricular (ICV) route to test the leptin sensitivity of the hypothalamus. RESULTS The excessive prepuberty androgen levels in the DHT-induced rats markedly elevated food intake prior to weight gain. Consistent with this, the expression of neuropeptide Y and agouti-related peptide mRNAs was upregulated, which occurred prior to obesity and even with restricted food intake. In addition, the hypothalamic sensitivity to insulin and leptin was also impaired in the DHT-induced rats before obesity and with restricted food intake. DHT significantly reduced the leptin levels in the CSF, and ICV injection of leptin inhibited the DHT-induced increase in food intake. CONCLUSIONS Androgen excess increased food intake in rats and promoted obesity by downregulating insulin and leptin signaling in the hypothalamus, most likely by suppressing leptin levels in the CSF.
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Affiliation(s)
- Ying Liu
- The State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
- Clinical Center of Reproductive Medicine, Xuzhou Central Hospital, Xuzhou Clinical School of Xuzhou Medical College, Xuzhou, China
| | - Yu-Chen Xu
- The State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Yu-Gui Cui
- The State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Shi-Wen Jiang
- Center of Reproductive Medicine, State Key Laboratory of Reproductive Medicine, Research Institute for Reproductive Health and Genetic Diseases, The Affiliated Wuxi Maternity and Child Health Care Hospital of Nanjing Medical University, Wuxi, China
| | - Fei-Yang Diao
- The State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Jia-Yin Liu
- The State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
- *Jia-yin Liu,
| | - Xiang Ma
- The State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
- **Xiang Ma,
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13
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Porniece Kumar M, Cremer AL, Klemm P, Steuernagel L, Sundaram S, Jais A, Hausen AC, Tao J, Secher A, Pedersen TÅ, Schwaninger M, Wunderlich FT, Lowell BB, Backes H, Brüning JC. Insulin signalling in tanycytes gates hypothalamic insulin uptake and regulation of AgRP neuron activity. Nat Metab 2021; 3:1662-1679. [PMID: 34931084 PMCID: PMC8688146 DOI: 10.1038/s42255-021-00499-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 10/26/2021] [Indexed: 12/02/2022]
Abstract
Insulin acts on neurons and glial cells to regulate systemic glucose metabolism and feeding. However, the mechanisms of insulin access in discrete brain regions are incompletely defined. Here we show that insulin receptors in tanycytes, but not in brain endothelial cells, are required to regulate insulin access to the hypothalamic arcuate nucleus. Mice lacking insulin receptors in tanycytes (IR∆Tan mice) exhibit systemic insulin resistance, while displaying normal food intake and energy expenditure. Tanycytic insulin receptors are also necessary for the orexigenic effects of ghrelin, but not for the anorexic effects of leptin. IR∆Tan mice exhibit increased agouti-related peptide (AgRP) neuronal activity, while displaying blunted AgRP neuronal adaptations to feeding-related stimuli. Lastly, a highly palatable food decreases tanycytic and arcuate nucleus insulin signalling to levels comparable to those seen in IR∆Tan mice. These changes are rooted in modifications of cellular stress responses and of mitochondrial protein quality control in tanycytes. Conclusively, we reveal a critical role of tanycyte insulin receptors in gating feeding-state-dependent regulation of AgRP neurons and systemic insulin sensitivity, and show that insulin resistance in tanycytes contributes to the pleiotropic manifestations of obesity-associated insulin resistance.
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Affiliation(s)
- Marta Porniece Kumar
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Anna Lena Cremer
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Paul Klemm
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Lukas Steuernagel
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Sivaraj Sundaram
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
| | - Alexander Jais
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig and University Hospital Leipzig, Leipzig, Germany
| | - A Christine Hausen
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Jenkang Tao
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
- Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Anna Secher
- Global Drug Discovery, Novo Nordisk A/S, Måløv, Denmark
| | | | - Markus Schwaninger
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
| | - F Thomas Wunderlich
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
- Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Heiko Backes
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Jens C Brüning
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany.
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (CEDP), University Hospital Cologne, Cologne, Germany.
- National Center for Diabetes Research (DZD), Neuherberg, Germany.
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14
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Uriarte M, De Francesco PN, Fernández G, Castrogiovanni D, D'Arcangelo M, Imbernon M, Cantel S, Denoyelle S, Fehrentz JA, Praetorius J, Prevot V, Perello M. Circulating ghrelin crosses the blood-cerebrospinal fluid barrier via growth hormone secretagogue receptor dependent and independent mechanisms. Mol Cell Endocrinol 2021; 538:111449. [PMID: 34478806 DOI: 10.1016/j.mce.2021.111449] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/13/2021] [Accepted: 08/30/2021] [Indexed: 01/17/2023]
Abstract
Ghrelin is a peptide hormone mainly secreted from gastrointestinal tract that acts via the growth hormone secretagogue receptor (GHSR), which is highly expressed in the brain. Strikingly, the accessibility of ghrelin to the brain seems to be limited and restricted to few brain areas. Previous studies in mice have shown that ghrelin can access the brain via the blood-cerebrospinal fluid (CSF) barrier, an interface constituted by the choroid plexus and the hypothalamic tanycytes. Here, we performed a variety of in vivo and in vitro studies to test the hypothesis that the transport of ghrelin across the blood-CSF barrier occurs in a GHSR-dependent manner. In vivo, we found that the uptake of systemically administered fluorescent ghrelin in the choroid plexus epithelial (CPE) cells and in hypothalamic tanycytes depends on the presence of GHSR. Also, we detected lower levels of CSF ghrelin after a systemic ghrelin injection in GHSR-deficient mice, as compared to WT mice. In vitro, the internalization of fluorescent ghrelin was reduced in explants of choroid plexus from GHSR-deficient mice, and unaffected in primary cultures of hypothalamic tanycytes derived from GHSR-deficient mice. Finally, we found that the GHSR mRNA is detected in a pool of CPE cells, but is nearly undetectable in hypothalamic tanycytes with current approaches. Thus, our results suggest that circulating ghrelin crosses the blood-CSF barrier mainly by a mechanism that involves the GHSR, and also possibly via a GHSR-independent mechanism.
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Affiliation(s)
- Maia Uriarte
- Laboratory of Neurophysiology, [Argentine Research Council (CONICET), Scientific Research Commission of the Province of Buenos Aires (CIC-PBA) and National University of La Plata (UNLP)], La Plata, Argentina
| | - Pablo N De Francesco
- Laboratory of Neurophysiology, [Argentine Research Council (CONICET), Scientific Research Commission of the Province of Buenos Aires (CIC-PBA) and National University of La Plata (UNLP)], La Plata, Argentina
| | - Gimena Fernández
- Laboratory of Neurophysiology, [Argentine Research Council (CONICET), Scientific Research Commission of the Province of Buenos Aires (CIC-PBA) and National University of La Plata (UNLP)], La Plata, Argentina
| | - Daniel Castrogiovanni
- Cell Culture Facility of the Multidisciplinary Institute of Cell Biology [Argentine Research Council (CONICET), Scientific Research Commission of the Province of Buenos Aires (CIC-PBA) and National University of La Plata (UNLP)], La Plata, Argentina
| | - Micaela D'Arcangelo
- Laboratory of Neurophysiology, [Argentine Research Council (CONICET), Scientific Research Commission of the Province of Buenos Aires (CIC-PBA) and National University of La Plata (UNLP)], La Plata, Argentina
| | - Mónica Imbernon
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience and Cognition, UMR, S1172, Lille, France
| | - Sonia Cantel
- Institut des Biomolécules Max Mousseron, UMR, 5247, CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, Montpellier, France
| | - Severine Denoyelle
- Institut des Biomolécules Max Mousseron, UMR, 5247, CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, Montpellier, France
| | - Jean-Alain Fehrentz
- Institut des Biomolécules Max Mousseron, UMR, 5247, CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, Montpellier, France
| | | | - Vincent Prevot
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience and Cognition, UMR, S1172, Lille, France
| | - Mario Perello
- Laboratory of Neurophysiology, [Argentine Research Council (CONICET), Scientific Research Commission of the Province of Buenos Aires (CIC-PBA) and National University of La Plata (UNLP)], La Plata, Argentina.
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15
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Abstract
A new mechanism of leptin extravasation from the bloodstream into the brain may have been discovered. According to recent findings by Butiaeva et al., pericytes within the blood-brain barrier (BBB) express the leptin receptor and, upon activation, facilitate the movement of the appetite-suppressing hormone into deeper regions of the hypothalamus.
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Affiliation(s)
- Daniel J Torres
- Pacific Biosciences Research Center, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI, USA.
| | - Matthew W Pitts
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, USA
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16
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Affiliation(s)
- Fredrik Anesten
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - John-Olov Jansson
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
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17
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Duquenne M, Folgueira C, Bourouh C, Millet M, Silva A, Clasadonte J, Imbernon M, Fernandois D, Martinez-Corral I, Kusumakshi S, Caron E, Rasika S, Deliglia E, Jouy N, Oishi A, Mazzone M, Trinquet E, Tavernier J, Kim YB, Ory S, Jockers R, Schwaninger M, Boehm U, Nogueiras R, Annicotte JS, Gasman S, Dam J, Prévot V. Leptin brain entry via a tanycytic LepR-EGFR shuttle controls lipid metabolism and pancreas function. Nat Metab 2021; 3:1071-1090. [PMID: 34341568 PMCID: PMC7611554 DOI: 10.1038/s42255-021-00432-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 06/23/2021] [Indexed: 01/14/2023]
Abstract
Metabolic health depends on the brain's ability to control food intake and nutrient use versus storage, processes that require peripheral signals such as the adipocyte-derived hormone, leptin, to cross brain barriers and mobilize regulatory circuits. We have previously shown that hypothalamic tanycytes shuttle leptin into the brain to reach target neurons. Here, using multiple complementary models, we show that tanycytes express functional leptin receptor (LepR), respond to leptin by triggering Ca2+ waves and target protein phosphorylation, and that their transcytotic transport of leptin requires the activation of a LepR-EGFR complex by leptin and EGF sequentially. Selective deletion of LepR in tanycytes blocks leptin entry into the brain, inducing not only increased food intake and lipogenesis but also glucose intolerance through attenuated insulin secretion by pancreatic β-cells, possibly via altered sympathetic nervous tone. Tanycytic LepRb-EGFR-mediated transport of leptin could thus be crucial to the pathophysiology of diabetes in addition to obesity, with therapeutic implications.
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Affiliation(s)
- Manon Duquenne
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
| | - Cintia Folgueira
- Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Cyril Bourouh
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur de Lille, CNRS, U1283-UMR 8199-EGID, Lille, France
| | - Marion Millet
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Anisia Silva
- Institut Cochin, Inserm U1016, CNRS UMR 8104, University Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Jérôme Clasadonte
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
| | - Monica Imbernon
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
| | - Daniela Fernandois
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
| | - Ines Martinez-Corral
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
| | - Soumya Kusumakshi
- Experimental Pharmacology, Center for Molecular Signaling, Saarland University School of Medicine, Homburg, Germany
| | - Emilie Caron
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
| | - S Rasika
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
| | - Eleonora Deliglia
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
| | - Nathalie Jouy
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France
- Flow Cytometry Core Facility, BioImaging Center of Lille, Hospital Campus, UMS2014-US41, Lille, France
| | - Asturo Oishi
- Institut Cochin, Inserm U1016, CNRS UMR 8104, University Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Massimiliano Mazzone
- Laboratory of Tumor Inflammation and Angiogenesis, Center for Cancer Biology, VIB, Department of Oncology, Leuven, Belgium
| | - Eric Trinquet
- Cisbio Bioassays, Parc Technologique Marcel Boiteux, Codolet, France
| | - Jan Tavernier
- VIB-UGent Center for Medical Biotechnology, Gent, Belgium
| | - Young-Bum Kim
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Stéphane Ory
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Ralf Jockers
- Institut Cochin, Inserm U1016, CNRS UMR 8104, University Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Markus Schwaninger
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
| | - Ulrich Boehm
- Experimental Pharmacology, Center for Molecular Signaling, Saarland University School of Medicine, Homburg, Germany
| | - Ruben Nogueiras
- Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
| | - Jean-Sébastien Annicotte
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur de Lille, CNRS, U1283-UMR 8199-EGID, Lille, France
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Julie Dam
- Institut Cochin, Inserm U1016, CNRS UMR 8104, University Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Vincent Prévot
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S1172, EGID, DISTALZ, Lille, France.
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18
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Butiaeva LI, Slutzki T, Swick HE, Bourguignon C, Robins SC, Liu X, Storch KF, Kokoeva MV. Leptin receptor-expressing pericytes mediate access of hypothalamic feeding centers to circulating leptin. Cell Metab 2021; 33:1433-1448.e5. [PMID: 34129812 DOI: 10.1016/j.cmet.2021.05.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 02/19/2021] [Accepted: 05/21/2021] [Indexed: 12/18/2022]
Abstract
Knowledge of how leptin receptor (LepR) neurons of the mediobasal hypothalamus (MBH) access circulating leptin is still rudimentary. Employing intravital microscopy, we found that almost half of the blood-vessel-enwrapping pericytes in the MBH express LepR. Selective disruption of pericytic LepR led to increased food intake, increased fat mass, and loss of leptin-dependent signaling in nearby LepR neurons. When delivered intravenously, fluorescently tagged leptin accumulated at hypothalamic LepR pericytes, which was attenuated upon pericyte-specific LepR loss. Because a paracellular tracer was also preferentially retained at LepR pericytes, we pharmacologically targeted regulators of inter-endothelial junction tightness and found that they affect LepR neuronal signaling and food intake. Optical imaging in MBH slices revealed a long-lasting, tonic calcium increase in LepR pericytes in response to leptin, suggesting pericytic contraction and vessel constriction. Together, our data indicate that LepR pericytes facilitate localized, paracellular blood-brain barrier leaks, enabling MBH LepR neurons to access circulating leptin.
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Affiliation(s)
- Liliia I Butiaeva
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada; Integrated Program in Neuroscience, McGill University, Montreal QC H3A 2B4, Canada
| | - Tal Slutzki
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada; Integrated Program in Neuroscience, McGill University, Montreal QC H3A 2B4, Canada
| | - Hannah E Swick
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada; Integrated Program in Neuroscience, McGill University, Montreal QC H3A 2B4, Canada
| | - Clément Bourguignon
- Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal QC H4H 1R3, Canada; Integrated Program in Neuroscience, McGill University, Montreal QC H3A 2B4, Canada
| | - Sarah C Robins
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada
| | - Xiaohong Liu
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada
| | - Kai-Florian Storch
- Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal QC H4H 1R3, Canada
| | - Maia V Kokoeva
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada.
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19
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Salgado M, García-Robles MÁ, Sáez JC. Purinergic signaling in tanycytes and its contribution to nutritional sensing. Purinergic Signal 2021; 17:607-618. [PMID: 34018139 DOI: 10.1007/s11302-021-09791-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 04/19/2021] [Indexed: 10/21/2022] Open
Abstract
Tanycytes are hypothalamic radial glial-like cells with an important role in the regulation of neuroendocrine axes and energy homeostasis. These cells have been implicated in glucose, amino acids, and fatty acid sensing in the hypothalamus of rodents, where they are strategically positioned. While their cell bodies contact the cerebrospinal fluid, their extensive processes contact neurons of the arcuate and ventromedial nuclei, protagonists in the regulation of food intake. A growing body of evidence has shown that purinergic signaling plays a relevant role in this homeostatic role of tanycytes, likely regulating the release of gliotransmitters that will modify the activity of satiety-controlling hypothalamic neurons. Connexin hemichannels have proven to be particularly relevant in these mechanisms since they are responsible for the release of ATP from tanycytes in response to nutritional signals. On the other hand, either ionotropic or metabotropic ATP receptors are involved in the generation of intracellular Ca2+ waves in response to hypothalamic nutrients, which can spread between glial cells and towards neighboring neurons. This review will summarize recent evidence that supports a nutrient sensor role for tanycytes, highlighting the participation of purinergic signaling in this process.
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Affiliation(s)
- Magdiel Salgado
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - María Á García-Robles
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
| | - Juan C Sáez
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.
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20
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Hayden MR, Banks WA. Deficient Leptin Cellular Signaling Plays a Key Role in Brain Ultrastructural Remodeling in Obesity and Type 2 Diabetes Mellitus. Int J Mol Sci 2021; 22:5427. [PMID: 34063911 PMCID: PMC8196569 DOI: 10.3390/ijms22115427] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/13/2021] [Accepted: 05/15/2021] [Indexed: 12/11/2022] Open
Abstract
The triad of obesity, metabolic syndrome (MetS), Type 2 diabetes mellitus (T2DM) and advancing age are currently global societal problems that are expected to grow over the coming decades. This triad is associated with multiple end-organ complications of diabetic vasculopathy (maco-microvessel disease), neuropathy, retinopathy, nephropathy, cardiomyopathy, cognopathy encephalopathy and/or late-onset Alzheimer's disease. Further, obesity, MetS, T2DM and their complications are associated with economical and individual family burdens. This review with original data focuses on the white adipose tissue-derived adipokine/hormone leptin and how its deficient signaling is associated with brain remodeling in hyperphagic, obese, or hyperglycemic female mice. Specifically, the ultrastructural remodeling of the capillary neurovascular unit, brain endothelial cells (BECs) and their endothelial glycocalyx (ecGCx), the blood-brain barrier (BBB), the ventricular ependymal cells, choroid plexus, blood-cerebrospinal fluid barrier (BCSFB), and tanycytes are examined in female mice with impaired leptin signaling from either dysfunction of the leptin receptor (DIO and db/db models) or the novel leptin deficiency (BTBR ob/ob model).
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Affiliation(s)
- Melvin R. Hayden
- Departments of Internal Medicine, Endocrinology Diabetes and Metabolism, Diabetes and Cardiovascular Disease Center, University of Missouri-Columbia School of Medicine, One Hospital Drive, Columbia, MO 65212, USA;
| | - William A. Banks
- Geriatrics Research, Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, 1660 S. Columbian Way, 810C/Bldg 1, Seattle, WA 98108, USA
- Department of Medicine, Division of Gerontology and Geriatric Medicine, University of Washington, Seattle, WA 98108, USA
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21
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Upton BA, D'Souza SP, Lang RA. QPLOT Neurons-Converging on a Thermoregulatory Preoptic Neuronal Population. Front Neurosci 2021; 15:665762. [PMID: 34017237 PMCID: PMC8130930 DOI: 10.3389/fnins.2021.665762] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/06/2021] [Indexed: 12/12/2022] Open
Abstract
The preoptic area of the hypothalamus is a homeostatic control center. The heterogeneous neurons in this nucleus function to regulate the sleep/wake cycle, reproduction, thirst and hydration, as well as thermogenesis and other metabolic responses. Several recent studies have analyzed preoptic neuronal populations and demonstrated neuronal subtype-specific roles in suppression of thermogenesis. These studies showed similar thermogenesis responses to chemogenetic modulation, and similar synaptic tracing patterns for neurons that were responsive to cold, to inflammatory stimuli, and to violet light. A reanalysis of single-cell/nucleus RNA-sequencing datasets of the preoptic nucleus indicate that these studies have converged on a common neuronal population that when activated, are sufficient to suppress thermogenesis. Expanding on a previous name for these neurons (Q neurons, which reflect their ability to promote quiescence and expression of Qrfp), we propose a new name: QPLOT neurons, to reflect numerous molecular markers of this population and to capture its broader roles in metabolic regulation. Here, we summarize previous findings on this population and present a unified description of QPLOT neurons, the excitatory preoptic neuronal population that integrate a variety of thermal, metabolic, hormonal and environmental stimuli in order to regulate metabolism and thermogenesis.
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Affiliation(s)
- Brian A Upton
- The Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Division of Pediatric Ophthalmology, Center for Chronobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Molecular and Developmental Biology Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States.,Medical Scientist Training Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Shane P D'Souza
- The Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Division of Pediatric Ophthalmology, Center for Chronobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Molecular and Developmental Biology Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Richard A Lang
- The Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Division of Pediatric Ophthalmology, Center for Chronobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Department of Ophthalmology, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
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22
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Yoo S, Kim J, Lyu P, Hoang TV, Ma A, Trinh V, Dai W, Jiang L, Leavey P, Duncan L, Won JK, Park SH, Qian J, Brown SP, Blackshaw S. Control of neurogenic competence in mammalian hypothalamic tanycytes. SCIENCE ADVANCES 2021; 7:eabg3777. [PMID: 34049878 PMCID: PMC8163082 DOI: 10.1126/sciadv.abg3777] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 04/09/2021] [Indexed: 05/07/2023]
Abstract
Hypothalamic tanycytes, radial glial cells that share many features with neuronal progenitors, can generate small numbers of neurons in the postnatal hypothalamus, but the identity of these neurons and the molecular mechanisms that control tanycyte-derived neurogenesis are unknown. In this study, we show that tanycyte-specific disruption of the NFI family of transcription factors (Nfia/b/x) robustly stimulates tanycyte proliferation and tanycyte-derived neurogenesis. Single-cell RNA sequencing (scRNA-seq) and single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq) analysis reveals that NFI (nuclear factor I) factors repress Sonic hedgehog (Shh) and Wnt signaling in tanycytes and modulation of these pathways blocks proliferation and tanycyte-derived neurogenesis in Nfia/b/x-deficient mice. Nfia/b/x-deficient tanycytes give rise to multiple mediobasal hypothalamic neuronal subtypes that can mature, fire action potentials, receive synaptic inputs, and selectively respond to changes in internal states. These findings identify molecular mechanisms that control tanycyte-derived neurogenesis, which can potentially be targeted to selectively remodel the hypothalamic neural circuitry that controls homeostatic physiological processes.
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Affiliation(s)
- Sooyeon Yoo
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
- Department of Pathology, Seoul National University Hospital, 71 Daehak-ro, Jongno-gu 03082, Republic of Korea
| | - Juhyun Kim
- Department of Psychiatry and Behavioral Science, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Pin Lyu
- Department of Ophthalmology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Thanh V Hoang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Alex Ma
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Vickie Trinh
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Weina Dai
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Lizhi Jiang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Patrick Leavey
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Leighton Duncan
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Jae-Kyung Won
- Department of Pathology, Seoul National University Hospital, 71 Daehak-ro, Jongno-gu 03082, Republic of Korea
| | - Sung-Hye Park
- Department of Pathology, Seoul National University Hospital, 71 Daehak-ro, Jongno-gu 03082, Republic of Korea
| | - Jiang Qian
- Department of Ophthalmology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Solange P Brown
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA.
- Department of Ophthalmology, Johns Hopkins University, Baltimore, MD 21205, USA
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
- Institute for Cell Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
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23
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Angiopoietin-Like Growth Factor Involved in Leptin Signaling in the Hypothalamus. Int J Mol Sci 2021; 22:ijms22073443. [PMID: 33810547 PMCID: PMC8037945 DOI: 10.3390/ijms22073443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/20/2021] [Accepted: 03/24/2021] [Indexed: 11/26/2022] Open
Abstract
The hypothalamic regulation of appetite governs whole-body energy balance. Satiety is regulated by endocrine factors including leptin, and impaired leptin signaling is associated with obesity. Despite the anorectic effect of leptin through the regulation of the hypothalamic feeding circuit, a distinct downstream mediator of leptin signaling in neuron remains unclear. Angiopoietin-like growth factor (AGF) is a peripheral activator of energy expenditure and antagonizes obesity. However, the regulation of AGF expression in brain and localization to mediate anorectic signaling is unknown. Here, we demonstrated that AGF is expressed in proopiomelanocortin (POMC)-expressing neurons located in the arcuate nucleus (ARC) of the hypothalamus. Unlike other brain regions, hypothalamic AGF expression is stimulated by leptin-induced signal transducers and activators of transcription 3 (STAT3) phosphorylation. In addition, leptin treatment to hypothalamic N1 cells significantly enhanced the promoter activity of AGF. This induction was abolished by the pretreatment of ruxolitinib, a leptin signaling inhibitor. These results indicate that hypothalamic AGF expression is induced by leptin and colocalized to POMC neurons.
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24
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Dardente H, Migaud M. Thyroid hormone and hypothalamic stem cells in seasonal functions. VITAMINS AND HORMONES 2021; 116:91-131. [PMID: 33752829 DOI: 10.1016/bs.vh.2021.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Seasonal rhythms are a pervasive feature of most living organisms, which underlie yearly timeliness in breeding, migration, hibernation or weight gain and loss. To achieve this, organisms have developed inner timing devices (circannual clocks) that endow them with the ability to predict then anticipate changes to come, usually using daylength as the proximate cue. In Vertebrates, daylength interpretation involves photoperiodic control of TSH production by the pars tuberalis (PT) of the pituitary, which governs a seasonal switch in thyroid hormone (TH) availability in the neighboring hypothalamus. Tanycytes, specialized glial cells lining the third ventricle (3V), are responsible for this TH output through the opposite, PT-TSH-driven, seasonal control of deiodinases 2/3 (Dio 2/3). Tanycytes comprise a photoperiod-sensitive stem cell niche and TH is known to play major roles in cell proliferation and differentiation, which suggests that seasonal control of tanycyte proliferation may be involved in the photoperiodic synchronization of seasonal rhythms. Here we review our current knowledge of the molecular and neuroendocrine pathway linking photoperiodic information to seasonal changes in physiological functions and discuss the potential implication of tanycytes, TH and cell proliferation in seasonal timing.
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Affiliation(s)
- Hugues Dardente
- PRC, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France.
| | - Martine Migaud
- PRC, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
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25
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Pereira S, Cline DL, Glavas MM, Covey SD, Kieffer TJ. Tissue-Specific Effects of Leptin on Glucose and Lipid Metabolism. Endocr Rev 2021; 42:1-28. [PMID: 33150398 PMCID: PMC7846142 DOI: 10.1210/endrev/bnaa027] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Indexed: 12/18/2022]
Abstract
The discovery of leptin was intrinsically associated with its ability to regulate body weight. However, the effects of leptin are more far-reaching and include profound glucose-lowering and anti-lipogenic effects, independent of leptin's regulation of body weight. Regulation of glucose metabolism by leptin is mediated both centrally and via peripheral tissues and is influenced by the activation status of insulin signaling pathways. Ectopic fat accumulation is diminished by both central and peripheral leptin, an effect that is beneficial in obesity-associated disorders. The magnitude of leptin action depends upon the tissue, sex, and context being examined. Peripheral tissues that are of particular relevance include the endocrine pancreas, liver, skeletal muscle, adipose tissues, immune cells, and the cardiovascular system. As a result of its potent metabolic activity, leptin is used to control hyperglycemia in patients with lipodystrophy and is being explored as an adjunct to insulin in patients with type 1 diabetes. To fully understand the role of leptin in physiology and to maximize its therapeutic potential, the mechanisms of leptin action in these tissues needs to be further explored.
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Affiliation(s)
- Sandra Pereira
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Daemon L Cline
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Maria M Glavas
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Scott D Covey
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada.,Department of Surgery, University of British Columbia, Vancouver, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, Canada
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26
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Tanycytes in the infundibular nucleus and median eminence and their role in the blood-brain barrier. HANDBOOK OF CLINICAL NEUROLOGY 2021; 180:253-273. [PMID: 34225934 DOI: 10.1016/b978-0-12-820107-7.00016-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The blood-brain barrier is generally attributed to endothelial cells. However, in circumventricular organs, such as the median eminence, tanycytes take over the barrier function. These ependymoglial cells form the wall of the third ventricle and send long extensions into the parenchyma to contact blood vessels and hypothalamic neurons. The shape and location of tanycytes put them in an ideal position to connect the periphery with central nervous compartments. In line with this, tanycytes control the transport of hormones and key metabolites in and out of the hypothalamus. They function as sensors of peripheral homeostasis for central regulatory networks. This chapter discusses current evidence that tanycytes play a key role in regulating glucose balance, food intake, endocrine axes, seasonal changes, reproductive function, and aging. The understanding of how tanycytes perform these diverse tasks is only just beginning to emerge and will probably lead to a more differentiated view of how the brain and the periphery interact.
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27
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Lebrun B, Barbot M, Tonon MC, Prévot V, Leprince J, Troadec JD. Glial endozepines and energy balance: Old peptides with new tricks. Glia 2020; 69:1079-1093. [PMID: 33105065 DOI: 10.1002/glia.23927] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/09/2020] [Accepted: 10/09/2020] [Indexed: 12/12/2022]
Abstract
The contribution of neuroglial interactions to the regulation of energy balance has gained increasing acceptance in recent years. In this context, endozepines, endogenous analogs of benzodiazepine derived from diazepam-binding inhibitor, are now emerging as major players. Produced by glial cells (astrocytes and tanycytes), endozepines have been known for two decades to exert potent anorexigenic effects by acting at the hypothalamic level. However, it is only recently that their modes of action, including the mechanisms by which they modulate energy metabolism, have begun to be elucidated. The data available today are abundant, significant, and sometimes contradictory, revealing a much more complex regulation than initially expected. Several mechanisms of action of endozepines seem to coexist at the central level, particularly in the hypothalamus. The brainstem has also recently emerged as a potential site of action for endozepines. In addition to their central anorexigenic effects, endozepines may also display peripheral effects promoting orexigenic actions, adding to their complexity and raising yet more questions. In this review, we attempt to provide an overview of our current knowledge in this rapidly evolving field and to pinpoint questions that remain unanswered.
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Affiliation(s)
- Bruno Lebrun
- CNRS 7291, Laboratoire de Neurosciences Cognitives, Aix Marseille University, Marseille, France
| | - Manon Barbot
- CNRS 7291, Laboratoire de Neurosciences Cognitives, Aix Marseille University, Marseille, France
| | - Marie-Christine Tonon
- INSERM U1239, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Normandie Université, Rouen, France
| | - Vincent Prévot
- University of Lille, INSERM, CHU Lille, Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience and Cognition, UMR-S 1172, European Genomic Institute of Diabetes (EGID), Lille, France
| | - Jérôme Leprince
- INSERM U1239, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Normandie Université, Rouen, France
| | - Jean-Denis Troadec
- CNRS 7291, Laboratoire de Neurosciences Cognitives, Aix Marseille University, Marseille, France
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28
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Yoo S, Cha D, Kim S, Jiang L, Cooke P, Adebesin M, Wolfe A, Riddle R, Aja S, Blackshaw S. Tanycyte ablation in the arcuate nucleus and median eminence increases obesity susceptibility by increasing body fat content in male mice. Glia 2020; 68:1987-2000. [PMID: 32173924 PMCID: PMC7423758 DOI: 10.1002/glia.23817] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 02/28/2020] [Accepted: 02/28/2020] [Indexed: 12/11/2022]
Abstract
Tanycytes are radial glial cells located in the mediobasal hypothalamus. Recent studies have proposed that tanycytes play an important role in hypothalamic control of energy homeostasis, although this has not been directly tested. Here, we report the phenotype of mice in which tanycytes of the arcuate nucleus and median eminence were conditionally ablated in adult mice. Although the cerebrospinal fluid-hypothalamic barrier was rendered more permeable following tanycyte ablation, neither the blood-hypothalamic barrier nor leptin-induced pSTAT3 activation in hypothalamic parenchyma were affected. We observed a significant increase in visceral fat distribution accompanying insulin insensitivity in male mice, without significant effect on either body weight or food intake. A high-fat diet tended to accelerate overall body weight gain in tanycyte-ablated mice, but the development of visceral adiposity and insulin insensitivity was comparable to wildtype. Thermoneutral housing exacerbated fat accumulation and produced a shift away from fat oxidation in tanycyte-ablated mice. These results clarify the extent to which tanycytes regulate energy balance, and demonstrate a role for tanycytes in regulating fat metabolism.
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Affiliation(s)
- Sooyeon Yoo
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - David Cha
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Soohyun Kim
- Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Lizhi Jiang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Patrick Cooke
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mobolanie Adebesin
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Andrew Wolfe
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ryan Riddle
- Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Baltimore Veterans Administration Medical Center, Baltimore, Maryland
| | - Susan Aja
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Center for Human Systems Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
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29
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Hristov M, Landzhov B, Yakimova K. Cafeteria diet-induced obesity reduces leptin-stimulated NADPH-diaphorase reactivity in the hypothalamic arcuate nucleus of rats. Acta Histochem 2020; 122:151616. [PMID: 33066838 DOI: 10.1016/j.acthis.2020.151616] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 08/08/2020] [Accepted: 08/17/2020] [Indexed: 02/07/2023]
Abstract
Leptin is an adipokine that plays an important role in the regulation of energy homeostasis. The failure of endogenous and exogenous leptin to mediate its effects (for example, at suppressing appetite and decreasing body weight) has been termed leptin resistance. Hyperleptinemia and leptin resistance can be well demonstrated in animals in which obesity is induced by consumption of a palatable, high-calorie diet (e.g., cafeteria diet-induced obesity). Since leptin receptor signaling is known to be impaired in the hypothalamic arcuate nucleus (ARC) of obese rodents, we investigated the effect of leptin on nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reactivity in the ARC of male Wistar rats with cafeteria diet-induced obesity. Our results have shown that after intraperitoneal administration of leptin, the number of NADPH-d positive neurons in the ARC was significantly lower in obese rats compared with that observed in normal weight rats. Additionally, we have found that leptin-induced NADPH-d staining in ARC neurons and the adjacent ependyma was decreased in obese rats. The results presented here suggest that the ability of leptin to activate nitric oxide synthase in neurons within the ARC as well as tanycytes and ependymal cells of the third ventricle is reduced in rats made obese by a cafeteria diet. We speculate that impairment in leptin-induced NO production presents a potential mechanism, involved in the pathogenesis of obesity and obesity-related disease states.
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Affiliation(s)
- Milen Hristov
- Department of Pharmacology and Toxicology, Faculty of Medicine, Medical University of Sofia, 2 "Zdrave" St., 1431 Sofia, Bulgaria.
| | - Boycho Landzhov
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Medical University of Sofia, 2 "Zdrave" St., 1431 Sofia, Bulgaria
| | - Krassimira Yakimova
- Department of Pharmacology and Toxicology, Faculty of Medicine, Medical University of Sofia, 2 "Zdrave" St., 1431 Sofia, Bulgaria
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30
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Kim DW, Washington PW, Wang ZQ, Lin SH, Sun C, Ismail BT, Wang H, Jiang L, Blackshaw S. The cellular and molecular landscape of hypothalamic patterning and differentiation from embryonic to late postnatal development. Nat Commun 2020; 11:4360. [PMID: 32868762 PMCID: PMC7459115 DOI: 10.1038/s41467-020-18231-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 08/12/2020] [Indexed: 12/22/2022] Open
Abstract
The hypothalamus is a central regulator of many innate behaviors essential for survival, but the molecular mechanisms controlling hypothalamic patterning and cell fate specification are poorly understood. To identify genes that control hypothalamic development, we have used single-cell RNA sequencing (scRNA-Seq) to profile mouse hypothalamic gene expression across 12 developmental time points between embryonic day 10 and postnatal day 45. This identified genes that delineated clear developmental trajectories for all major hypothalamic cell types, and readily distinguished major regional subdivisions of the developing hypothalamus. By using our developmental dataset, we were able to rapidly annotate previously unidentified clusters from existing scRNA-Seq datasets collected during development and to identify the developmental origins of major neuronal populations of the ventromedial hypothalamus. We further show that our approach can rapidly and comprehensively characterize mutants that have altered hypothalamic patterning, identifying Nkx2.1 as a negative regulator of prethalamic identity. These data serve as a resource for further studies of hypothalamic development, physiology, and dysfunction.
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Affiliation(s)
- Dong Won Kim
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Parris Whitney Washington
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Zoe Qianyi Wang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Sonia Hao Lin
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Changyu Sun
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Basma Taleb Ismail
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Hong Wang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Lizhi Jiang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Center for Human Systems Biology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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31
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Helfer G, Stevenson TJ. Pleiotropic effects of proopiomelanocortin and VGF nerve growth factor inducible neuropeptides for the long-term regulation of energy balance. Mol Cell Endocrinol 2020; 514:110876. [PMID: 32473184 DOI: 10.1016/j.mce.2020.110876] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/14/2020] [Accepted: 05/18/2020] [Indexed: 12/16/2022]
Abstract
Seasonal rhythms in energy balance are well documented across temperate and equatorial zones animals. The long-term regulated changes in seasonal physiology consists of a rheostatic system that is essential to successful time annual cycles in reproduction, hibernation, torpor, and migration. Most animals use the annual change in photoperiod as a reliable and robust environmental cue to entrain endogenous (i.e. circannual) rhythms. Research over the past few decades has predominantly examined the role of first order neuroendocrine peptides for the rheostatic changes in energy balance. These anorexigenic and orexigenic neuropeptides in the arcuate nucleus include neuropeptide y (Npy), agouti-related peptide (Agrp), cocaine and amphetamine related transcript (Cart) and pro-opiomelanocortin (Pomc). Recent studies also indicate that VGF nerve growth factor inducible (Vgf) in the arcuate nucleus is involved in the seasonal regulation of energy balance. In situ hybridization, qPCR and RNA-sequencing studies have identified that Pomc expression across fish, avian and mammalian species, is a neuroendocrine marker that reflects seasonal energetic states. Here we highlight that long-term changes in arcuate Pomc and Vgf expression is conserved across species and may provide rheostatic regulation of seasonal energy balance.
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Affiliation(s)
- Gisela Helfer
- Faculty of Life Sciences, University of Bradford, Bradford, UK
| | - Tyler J Stevenson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK.
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32
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Nogueira G, Solon C, Carraro RS, Engel DF, Ramalho AF, Sidarta-Oliveira D, Gaspar RS, Bombassaro B, Vasques AC, Geloneze B, Vinolo MA, Donato Junior J, Velloso LA. Interleukin-17 acts in the hypothalamus reducing food intake. Brain Behav Immun 2020; 87:272-285. [PMID: 31863824 DOI: 10.1016/j.bbi.2019.12.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/20/2019] [Accepted: 12/16/2019] [Indexed: 12/12/2022] Open
Abstract
Interleukin-17 (IL-17) is expressed in the intestine in response to changes in the gut microbiome landscape and plays an important role in intestinal and systemic inflammatory diseases. There is evidence that dietary factors can also modify the expression of intestinal IL-17. Here, we hypothesized that, similar to several other gut-produced factors, IL-17 may act in the hypothalamus to modulate food intake. We confirm that food intake increases IL-17 expression in the mouse ileum and human blood. There is no expression of IL-17 in the hypothalamus; however, IL-17 receptor A is expressed in both pro-opiomelanocortin (POMC) and agouti-related peptide (AgRP) neurons. Upon systemic injection, IL-17 promoted a rapid increase in hypothalamic POMC expression, which was followed by a late increase in the expression of AgRP. Both systemic and intracerebroventricular injections of IL-17 reduced calorie intake without affecting whole-body energy expenditure. Systemic but not intracerebroventricular injection of IL-17 increase brown adipose tissue temperature. Thus, IL-17 is a gut-produced factor that is controlled by diet and modulates food intake by acting in the hypothalamus. Our findings provide the first evidence of a cytokine that is acutely regulated by food intake and plays a role in the regulation of eating.
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Affiliation(s)
- Guilherme Nogueira
- Laboratory of Cell Signalling-Obesity and Comorbidities Research Center, University of Campinas, Campinas, Brazil
| | - Carina Solon
- Laboratory of Cell Signalling-Obesity and Comorbidities Research Center, University of Campinas, Campinas, Brazil
| | - Rodrigo S Carraro
- Laboratory of Cell Signalling-Obesity and Comorbidities Research Center, University of Campinas, Campinas, Brazil
| | - Daiane F Engel
- Laboratory of Cell Signalling-Obesity and Comorbidities Research Center, University of Campinas, Campinas, Brazil
| | - Albina F Ramalho
- Laboratory of Cell Signalling-Obesity and Comorbidities Research Center, University of Campinas, Campinas, Brazil
| | - Davi Sidarta-Oliveira
- Laboratory of Cell Signalling-Obesity and Comorbidities Research Center, University of Campinas, Campinas, Brazil
| | - Rodrigo S Gaspar
- Laboratory of Cell Signalling-Obesity and Comorbidities Research Center, University of Campinas, Campinas, Brazil
| | - Bruna Bombassaro
- Laboratory of Cell Signalling-Obesity and Comorbidities Research Center, University of Campinas, Campinas, Brazil
| | - Ana C Vasques
- Laboratory of Investigation in Metabolism and Diabetes, University of Campinas, Campinas, Brazil
| | - Bruno Geloneze
- Laboratory of Investigation in Metabolism and Diabetes, University of Campinas, Campinas, Brazil
| | - Marco A Vinolo
- Laboratory of Immunoinflammation, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas, Campinas, Brazil
| | - Jose Donato Junior
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Licio A Velloso
- Laboratory of Cell Signalling-Obesity and Comorbidities Research Center, University of Campinas, Campinas, Brazil.
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33
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Venema W, Severi I, Perugini J, Di Mercurio E, Mainardi M, Maffei M, Cinti S, Giordano A. Ciliary Neurotrophic Factor Acts on Distinctive Hypothalamic Arcuate Neurons and Promotes Leptin Entry Into and Action on the Mouse Hypothalamus. Front Cell Neurosci 2020; 14:140. [PMID: 32528252 PMCID: PMC7253709 DOI: 10.3389/fncel.2020.00140] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 04/24/2020] [Indexed: 12/13/2022] Open
Abstract
In humans and experimental animals, the administration of ciliary neurotrophic factor (CNTF) reduces food intake and body weight. To gain further insights into the mechanism(s) underlying its satiety effect, we: (i) evaluated the CNTF-dependent activation of the Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) pathway in mouse models where neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) neurons can be identified by green fluorescent protein (GFP); and (ii) assessed whether CNTF promotes leptin signaling in hypothalamic feeding centers. Immunohistochemical experiments enabled us to establish that intraperitoneal injection of mouse recombinant CNTF activated the JAK2-STAT3 pathway in a substantial proportion of arcuate nucleus (ARC) NPY neurons (18.68% ± 0.60 in 24-h fasted mice and 25.50% ± 1.17 in fed mice) but exerted a limited effect on POMC neurons (4.15% ± 0.33 in 24-h fasted mice and 2.84% ± 0.45 in fed mice). CNTF-responsive NPY neurons resided in the ventromedial ARC, facing the median eminence (ME), and were surrounded by albumin immunoreactivity, suggesting that they are located outside the blood-brain barrier (BBB). In both normally fed and high-fat diet (HFD) obese animals, CNTF activated extracellular signal-regulated kinase signaling in ME β1- and β2-tanycytes, an effect that has been linked to the promotion of leptin entry into the brain. Accordingly, compared to the animals treated with leptin, mice treated with leptin/CNTF showed: (i) a significantly greater leptin content in hypothalamic protein extracts; (ii) a significant increase in phospho-STAT3 (P-STAT3)-positive neurons in the ARC and the ventromedial hypothalamic nucleus of normally fed mice; and (iii) a significantly increased number of P-STAT3-positive neurons in the ARC and dorsomedial hypothalamic nucleus of HFD obese mice. Collectively, these data suggest that exogenously administered CNTF reduces food intake by exerting a leptin-like action on distinctive NPY ARC neurons and by promoting leptin signaling in hypothalamic feeding centers.
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Affiliation(s)
- Wiebe Venema
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica Delle Marche, Ancona, Italy
| | - Ilenia Severi
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica Delle Marche, Ancona, Italy
| | - Jessica Perugini
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica Delle Marche, Ancona, Italy
| | - Eleonora Di Mercurio
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica Delle Marche, Ancona, Italy
| | - Marco Mainardi
- Institute of Neuroscience, National Research Council, Pisa, Italy
| | | | - Saverio Cinti
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica Delle Marche, Ancona, Italy.,Center of Obesity, Università Politecnica delle Marche-United Hospitals, Ancona, Italy
| | - Antonio Giordano
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica Delle Marche, Ancona, Italy
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de Araújo TM, Velloso LA. Hypothalamic IRX3: A New Player in the Development of Obesity. Trends Endocrinol Metab 2020; 31:368-377. [PMID: 32035736 DOI: 10.1016/j.tem.2020.01.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 01/06/2020] [Accepted: 01/09/2020] [Indexed: 12/15/2022]
Abstract
Genome-wide association studies (GWASs) have identified SNPs of the fat mass and obesity (FTO) gene as the most important risk alleles for obesity. However, how the presence of risk alleles affect phenotype is still a matter of intense investigation. In 2014, a study revealed that long-range enhancers from the intronic regions of the FTO gene regulate iroquois-class homeobox protein (IRX)3 expression. IRX3 is expressed in hypothalamic pro-opiomelanocortin (POMC) neurons and changes in its expression levels affect body adiposity by modifying food intake and energy expenditure. These findings have placed IRX3 as a potential target for the treatment of obesity. Here, we review studies that evaluated the roles of IRX3 in development, neurogenesis, and body energy homeostasis.
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Affiliation(s)
- Thiago Matos de Araújo
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas (UNICAMP), Campinas, Brazil
| | - Licio A Velloso
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas (UNICAMP), Campinas, Brazil.
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Langlet F. Targeting Tanycytes: Balance between Efficiency and Specificity. Neuroendocrinology 2020; 110:574-581. [PMID: 31986518 DOI: 10.1159/000505549] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 12/18/2019] [Indexed: 11/19/2022]
Abstract
Tanycytes are peculiar ependymoglial cells lining the bottom and the lateral wall of the third ventricle. For a decade, the utilization of molecular genetic approaches allowed us to make important discoveries about their diverse physiological functions. Here, I review the current methods used to target tanycytes, focusing on their specificity, their efficiency, their limitations, as well as their potential future improvements.
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Affiliation(s)
- Fanny Langlet
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland,
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Müller-Fielitz H, Schwaninger M. The Role of Tanycytes in the Hypothalamus-Pituitary-Thyroid Axis and
the Possibilities for Their Genetic Manipulation. Exp Clin Endocrinol Diabetes 2019; 128:388-394. [DOI: 10.1055/a-1065-1855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
AbstractThyroid hormone (TH) regulation is important for development, energy homeostasis,
heart function, and bone formation. To control the effects of TH in target
organs, the hypothalamus-pituitary-thyroid (HPT) axis and the tissue-specific
availability of TH are highly regulated by negative feedback. To exert a central
feedback, TH must enter the brain via specific transport mechanisms and cross
the blood-brain barrier. Here, tanycytes, which are located in the ventral walls
of the 3rd ventricle in the mediobasal hypothalamus (MBH), function as
gatekeepers. Tanycytes are able to transport, sense, and modify the release of
hormones of the HPT axis and are involved in feedback regulation. In this
review, we focus on the relevance of tanycytes in thyrotropin-releasing hormone
(TRH) release and review available genetic tools to investigate the
physiological functions of these cells.
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Affiliation(s)
- Helge Müller-Fielitz
- Institute for Experimental and Clinical Pharmacology and Toxicology,
Lübeck, University of Lübeck, Germany
| | - Markus Schwaninger
- Institute for Experimental and Clinical Pharmacology and Toxicology,
Lübeck, University of Lübeck, Germany
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Abstract
The discovery of leptin changed the view of adipose tissue from that of a passive vessel that stores fat to that of a dynamic endocrine organ that actively regulates behaviour and metabolism. Secreted by adipose tissue, leptin functions as an afferent signal in a negative feedback loop, acting primarily on neurons in the hypothalamus and regulating feeding and many other functions. The leptin endocrine system serves a critical evolutionary function by maintaining the relative constancy of adipose tissue mass, thereby protecting individuals from the risks associated with being too thin (starvation and infertility) or too obese (predation). In this Review, the biology of leptin is summarized, and a conceptual framework is established for studying the pathogenesis of obesity, which, analogously to diabetes, can result from either leptin hyposecretion or leptin resistance. Herein, these two states are distinguished with the terms 'type 1 obesity' and 'type 2 obesity': type 1 obesity describes a subset of obese individuals with low endogenous plasma leptin levels who respond to leptin therapy, whereas type 2 obesity describes most obese individuals, who are leptin resistant but might respond to leptin therapy in combination with other drugs, such as leptin sensitizers.
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Affiliation(s)
- Jeffrey M Friedman
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA.
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