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Qi G, Tang H, Hu J, Kang S, Qin S. Potential role of tanycyte-derived neurogenesis in Alzheimer's disease. Neural Regen Res 2025; 20:1599-1612. [PMID: 38934388 DOI: 10.4103/nrr.nrr-d-23-01865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 04/17/2024] [Indexed: 06/28/2024] Open
Abstract
Tanycytes, specialized ependymal cells located in the hypothalamus, play a crucial role in the generation of new neurons that contribute to the neural circuits responsible for regulating the systemic energy balance. The precise coordination of the gene networks controlling neurogenesis in naive and mature tanycytes is essential for maintaining homeostasis in adulthood. However, our understanding of the molecular mechanisms and signaling pathways that govern the proliferation and differentiation of tanycytes into neurons remains limited. This article aims to review the recent advancements in research into the mechanisms and functions of tanycyte-derived neurogenesis. Studies employing lineage-tracing techniques have revealed that the neurogenesis specifically originating from tanycytes in the hypothalamus has a compensatory role in neuronal loss and helps maintain energy homeostasis during metabolic diseases. Intriguingly, metabolic disorders are considered early biomarkers of Alzheimer's disease. Furthermore, the neurogenic potential of tanycytes and the state of newborn neurons derived from tanycytes heavily depend on the maintenance of mild microenvironments, which may be disrupted in Alzheimer's disease due to the impaired blood-brain barrier function. However, the specific alterations and regulatory mechanisms governing tanycyte-derived neurogenesis in Alzheimer's disease remain unclear. Accumulating evidence suggests that tanycyte-derived neurogenesis might be impaired in Alzheimer's disease, exacerbating neurodegeneration. Confirming this hypothesis, however, poses a challenge because of the lack of long-term tracing and nucleus-specific analyses of newborn neurons in the hypothalamus of patients with Alzheimer's disease. Further research into the molecular mechanisms underlying tanycyte-derived neurogenesis holds promise for identifying small molecules capable of restoring tanycyte proliferation in neurodegenerative diseases. This line of investigation could provide valuable insights into potential therapeutic strategies for Alzheimer's disease and related conditions.
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Affiliation(s)
- Guibo Qi
- Department of Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Han Tang
- Department of Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Jianian Hu
- Department of Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Siying Kang
- Department of Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Song Qin
- Department of Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Fudan University, Shanghai, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
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2
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Goggin SM, Zunder ER. ESCHR: a hyperparameter-randomized ensemble approach for robust clustering across diverse datasets. Genome Biol 2024; 25:242. [PMID: 39285487 DOI: 10.1186/s13059-024-03386-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 08/30/2024] [Indexed: 09/19/2024] Open
Abstract
Clustering is widely used for single-cell analysis, but current methods are limited in accuracy, robustness, ease of use, and interpretability. To address these limitations, we developed an ensemble clustering method that outperforms other methods at hard clustering without the need for hyperparameter tuning. It also performs soft clustering to characterize continuum-like regions and quantify clustering uncertainty, demonstrated here by mapping the connectivity and intermediate transitions between MNIST handwritten digits and between hypothalamic tanycyte subpopulations. This hyperparameter-randomized ensemble approach improves the accuracy, robustness, ease of use, and interpretability of single-cell clustering, and may prove useful in other fields as well.
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Affiliation(s)
- Sarah M Goggin
- Neuroscience Graduate Program, School of Medicine, University of Virginia, Charlottesville, VA, 22902, USA
| | - Eli R Zunder
- Neuroscience Graduate Program, School of Medicine, University of Virginia, Charlottesville, VA, 22902, USA.
- Department of Biomedical Engineering, School of Engineering, University of Virginia, Charlottesville, VA, 22902, USA.
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3
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Esteve NA, Rogers DJ, Stagray JA, Mayeux H, Nora G, Huval L, Smith KM. Tanycyte radial morphology and proliferation are influenced by fibroblast growth factor receptor 1 and high-fat diet. Eur J Neurosci 2024; 60:5000-5018. [PMID: 39087621 DOI: 10.1111/ejn.16473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 04/19/2024] [Accepted: 07/07/2024] [Indexed: 08/02/2024]
Abstract
Fibroblast growth factor receptor 1 (FGFR1) is a widely expressed, membrane-bound receptor that transduces extracellular signals from FGF ligands and cadherins, resulting in intracellular signals influencing cellular growth, proliferation, calcium, and transcription. FGF21 and FGF2 stimulate the proliferation of tanycytes, specialized radial astrocytes along the ventricle of the hypothalamus, and influence metabolism. Tanycytes are in a privileged position between the cerebrospinal fluid, the blood supply in the median eminence, and neurons within nuclei in the hypothalamus. The effect of FGFR1 signaling upon tanycyte morphology and metabolism was examined in adult mice with conditional deletion of the Fgfr1 gene using the Fgfr1flox/flox; Nestin-Cre+ line. Loss of Fgfr1 resulted in shorter β tanycytes along the medial eminence. Control Fgfr1flox/flox littermates and Fgfr1flox/flox, Nestin-Cre+ (Fgfr1 cKO) knockout mice were placed on a 1-month long high-fat diet (HFD) or a normal-fat diet (NFD), to investigate differences in body homeostasis and tanycyte morphology under an obesity inducing diet. We found that FGFR1 is a vital contributor to tanycyte morphology and quantity and that it promotes stem cell maintenance in the hypothalamus and hippocampal dentate gyrus. The Fgfr1 cKO mice developed impaired tolerance to a glucose challenge test on a HFD without gaining more weight than control mice. The combination of HFD and loss of Fgfr1 gene resulted in altered β and α tanycyte morphology, and reduced stem cell numbers along the third ventricle of the hypothalamus and hippocampus.
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Affiliation(s)
- N Alex Esteve
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisianafs, USA
| | - Deborah J Rogers
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisianafs, USA
| | - Jacob A Stagray
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisianafs, USA
| | - Holly Mayeux
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisianafs, USA
| | - Glenae Nora
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisianafs, USA
| | - Luke Huval
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisianafs, USA
| | - Karen Müller Smith
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisianafs, USA
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4
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Sui X, Jiang S, Zhang H, Wu F, Wang H, Yang C, Guo Y, Wang L, Li Y, Dai Z. The influence of extended fasting on thyroid hormone: local and differentiated regulatory mechanisms. Front Endocrinol (Lausanne) 2024; 15:1443051. [PMID: 39253586 PMCID: PMC11381305 DOI: 10.3389/fendo.2024.1443051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 08/07/2024] [Indexed: 09/11/2024] Open
Abstract
The hypometabolism induced by fasting has great potential in maintaining health and improving survival in extreme environments, among which thyroid hormone (TH) plays an important role in the adaptation and the formation of new energy metabolism homeostasis during long-term fasting. In the present review, we emphasize the potential of long-term fasting to improve physical health and emergency rescue in extreme environments, introduce the concept and pattern of fasting and its impact on the body's energy metabolism consumption. Prolonged fasting has more application potential in emergency rescue in special environments. The changes of THs caused by fasting, including serum biochemical characteristics, responsiveness of the peripheral and central hypothalamus-pituitary-thyroid (HPT) axis, and differential changes of TH metabolism, are emphasized in particular. It was proposed that the variability between brain and liver tissues in THs uptake, deiodination activation and inactivation is the key regulatory mechanism for the cause of peripheral THs decline and central homeostasis. While hypothalamic tanycytes play a pivotal role in the fine regulation of the HPT negative feedback regulation during long-term fasting. The study progress of tanycytes on thyrotropin-releasing hormone (TRH) release and deiodination is described in detail. In conclusion, the combination of the decrease of TH metabolism in peripheral tissues and stability in the central HPT axis maintains the basal physiological requirement and new energy metabolism homeostasis to adapt to long-term food scarcity. The molecular mechanisms of this localized and differential regulation will be a key research direction for developing measures for hypometabolic applications in extreme environment.
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Affiliation(s)
- Xiukun Sui
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Siyu Jiang
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Hongyu Zhang
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Feng Wu
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Hailong Wang
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Chao Yang
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Yaxiu Guo
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Linjie Wang
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Yinghui Li
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Zhongquan Dai
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
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5
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Brunner M, Lopez-Rodriguez D, Estrada-Meza J, Dali R, Rohrbach A, Deglise T, Messina A, Thorens B, Santoni F, Langlet F. Fasting induces metabolic switches and spatial redistributions of lipid processing and neuronal interactions in tanycytes. Nat Commun 2024; 15:6604. [PMID: 39098920 PMCID: PMC11298547 DOI: 10.1038/s41467-024-50913-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 07/25/2024] [Indexed: 08/06/2024] Open
Abstract
The ependyma lining the third ventricle (3V) in the mediobasal hypothalamus plays a crucial role in energy balance and glucose homeostasis. It is characterized by a high functional heterogeneity and plasticity, but the underlying molecular mechanisms governing its features are not fully understood. Here, 5481 hypothalamic ependymocytes were cataloged using FACS-assisted scRNAseq from fed, 12h-fasted, and 24h-fasted adult male mice. With standard clustering analysis, typical ependymal cells and β2-tanycytes appear sharply defined, but other subpopulations, β1- and α-tanycytes, display fuzzy boundaries with few or no specific markers. Pseudospatial approaches, based on the 3V neuroanatomical distribution, enable the identification of specific versus shared tanycyte markers and subgroup-specific versus general tanycyte functions. We show that fasting dynamically shifts gene expression patterns along the 3V, leading to a spatial redistribution of cell type-specific responses. Altogether, we show that changes in energy status induce metabolic and functional switches in tanycyte subpopulations, providing insights into molecular and functional diversity and plasticity within the tanycyte population.
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Affiliation(s)
- Maxime Brunner
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Lausanne, Switzerland
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - David Lopez-Rodriguez
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Judith Estrada-Meza
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Rafik Dali
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Antoine Rohrbach
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Tamara Deglise
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Andrea Messina
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Lausanne, Switzerland
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Bernard Thorens
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Federico Santoni
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Lausanne, Switzerland.
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
- Institute for Genetic and Biomedical Research (IRGB) - CNR, Monserrato, Italy.
| | - Fanny Langlet
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
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6
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Bai Y, Chen Q, Li Y. A single-cell transcriptomic study of heterogeneity in human embryonic tanycytes. Sci Rep 2024; 14:15384. [PMID: 38965316 PMCID: PMC11224400 DOI: 10.1038/s41598-024-66044-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 06/26/2024] [Indexed: 07/06/2024] Open
Abstract
Disruptions in energy homeostasis can lead to diseases like obesity and diabetes, affecting millions of people each year. Tanycytes, the adult stem cells in the hypothalamus, play crucial roles in assisting hypothalamic neurons in maintaining energy balance. Although tanycytes have been extensively studied in rodents, our understanding of human tanycytes remains limited. In this study, we utilized single-cell transcriptomics data to explore the heterogeneity of human embryonic tanycytes, investigate their gene regulatory networks, analyze their intercellular communication, and examine their developmental trajectory. Our analysis revealed the presence of two clusters of β tanycytes and three clusters of α tanycytes in our dataset. Surprisingly, human embryonic tanycytes displayed significant similarities to mouse tanycytes in terms of marker gene expression and transcription factor activities. Trajectory analysis indicated that α tanycytes were the first to be generated, giving rise to β tanycytes in a dorsal-ventral direction along the third ventricle. Furthermore, our CellChat analyses demonstrated that tanycytes generated earlier along the developmental lineages exhibited increased intercellular communication compared to those generated later. In summary, we have thoroughly characterized the heterogeneity of human embryonic tanycytes from various angles. We are confident that our findings will serve as a foundation for future research on human tanycytes.
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Affiliation(s)
- Yiguang Bai
- Department of Orthopaedics, The Second Clinical Institute of North Sichuan Medical College Nanchong, Nanchong Central Hospital, Nanchong, Sichuan, China.
- Nanchong Hospital of Beijing Anzhen Hospital Capital Medical University Sichuan, Beijing, China.
| | - Qiaoling Chen
- Department of Oncology, The Second Clinical Institute of North Sichuan Medical College Nanchong, Nanchong Central Hospital, Nanchong, Sichuan, China
- Nanchong Hospital of Beijing Anzhen Hospital Capital Medical University Sichuan, Beijing, China
| | - Yuan Li
- National Bioinformatics Infrastructure Sweden (NBIS), Science for Life Laboratory, Lund University, 223 87, Lund, Sweden.
- Department of Immunotechnology, Lund University, Medicon Village, 22387, Lund, Sweden.
- Human Neural Developmental Biology; BMC B11, Department of Experimental Medical Science Lund, Stem Cell Centre, Lund University, 22184, Lund, Sweden.
- Cell, Tissue & Organ Engineering Laboratory; BMC B11, Department of Clinical Sciences Lund, Stem Cell Centre, Lund University, 22184, Lund, Sweden.
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7
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Zangerolamo L, Carvalho M, Velloso LA, Barbosa HCL. Endocrine FGFs and their signaling in the brain: Relevance for energy homeostasis. Eur J Pharmacol 2024; 963:176248. [PMID: 38056616 DOI: 10.1016/j.ejphar.2023.176248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/10/2023] [Accepted: 11/30/2023] [Indexed: 12/08/2023]
Abstract
Since their discovery in 2000, there has been a continuous expansion of studies investigating the physiology, biochemistry, and pharmacology of endocrine fibroblast growth factors (FGFs). FGF19, FGF21, and FGF23 comprise a subfamily with attributes that distinguish them from typical FGFs, as they can act as hormones and are, therefore, referred to as endocrine FGFs. As they participate in a broad cross-organ endocrine signaling axis, endocrine FGFs are crucial lipidic, glycemic, and energetic metabolism regulators during energy availability fluctuations. They function as powerful metabolic signals in physiological responses induced by metabolic diseases, like type 2 diabetes and obesity. Pharmacologically, FGF19 and FGF21 cause body weight loss and ameliorate glucose homeostasis and energy expenditure in rodents and humans. In contrast, FGF23 expression in mice and humans has been linked with insulin resistance and obesity. Here, we discuss emerging concepts in endocrine FGF signaling in the brain and critically assess their putative role as therapeutic targets for treating metabolic disorders.
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Affiliation(s)
- Lucas Zangerolamo
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Sao Paulo, Brazil
| | - Marina Carvalho
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Sao Paulo, Brazil
| | - Licio A Velloso
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Sao Paulo, Brazil
| | - Helena C L Barbosa
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Sao Paulo, Brazil.
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8
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Manocchio F, Bravo FI, Helfer G, Muguerza B. Cherries with Different Geographical Origins Regulate Neuroprotection in a Photoperiod-Dependent Manner in F344 Rats. Antioxidants (Basel) 2024; 13:72. [PMID: 38247496 PMCID: PMC10812723 DOI: 10.3390/antiox13010072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/24/2023] [Accepted: 12/27/2023] [Indexed: 01/23/2024] Open
Abstract
The photoperiod is the main environmental cue that drives seasonal adaptive responses in reproduction, behavior, and metabolism in seasonal animals. Increasing evidence suggests that (poly)phenols contained in fruits can also modulate seasonal rhythms. (Poly)phenol-rich diets are associated with an improvement in cognitive function and neuroprotection due to their anti-inflammatory and antioxidative properties. However, it is unknown whether cherries affect neuroprotection in a photoperiod-dependent manner. To test this, F344 rats were exposed to L6 (6 h light/day), L12 (12 h light/day) and L18 (18 h light/day) photoperiods and fed a standard chow diet supplemented with either a control, lyophilized cherry 1 or cherry 2 with distinctive phenolic hallmarks. Physiological parameters (body weight, eating pattern index (EPI), testosterone, T4/T3) and hypothalamic key genes (Dio2, Dio3, Raldh1 and Ghrh) were strongly regulated by the photoperiod and/or fruit consumption. Importantly, we show for the first time that neurotrophs (Bdnf, Sod1 and Gpx1) in the hippocampus are also regulated by the photoperiod. Furthermore, the consumption of cherry 2, which was richer in total flavonols, but not cherry 1, which was richer in total anthocyanins and flavanols, enhanced neuroprotection in the hippocampus. Our results show that the seasonal consumption of cherry with a specific phenolic composition plays an important role in the hippocampal activation of neuroprotection in a photoperiod-dependent manner.
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Affiliation(s)
- Francesca Manocchio
- Nutrigenomics Research Group, Department of Biochemistry and Biotechnology, Universitat Rovira i Virgili, C Marcel·lí Domingo s/n, 43007 Tarragona, Spain; (F.M.); (B.M.)
- Nutrigenomics Research Group, Institut d’Investigació Sanitària Pere Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain
- Center of Environmental, Food and Toxicological Technology (TecnATox), Universitat Rovira i Virgili, 43007 Tarragona, Spain
| | - Francisca Isabel Bravo
- Nutrigenomics Research Group, Department of Biochemistry and Biotechnology, Universitat Rovira i Virgili, C Marcel·lí Domingo s/n, 43007 Tarragona, Spain; (F.M.); (B.M.)
- Nutrigenomics Research Group, Institut d’Investigació Sanitària Pere Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain
- Center of Environmental, Food and Toxicological Technology (TecnATox), Universitat Rovira i Virgili, 43007 Tarragona, Spain
| | - Gisela Helfer
- School of Chemistry and Biosciences, University of Bradford, Richmond Road, Bradford BD7 1DP, UK
| | - Begoña Muguerza
- Nutrigenomics Research Group, Department of Biochemistry and Biotechnology, Universitat Rovira i Virgili, C Marcel·lí Domingo s/n, 43007 Tarragona, Spain; (F.M.); (B.M.)
- Nutrigenomics Research Group, Institut d’Investigació Sanitària Pere Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain
- Center of Environmental, Food and Toxicological Technology (TecnATox), Universitat Rovira i Virgili, 43007 Tarragona, Spain
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9
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Goggin SM, Zunder ER. A hyperparameter-randomized ensemble approach for robust clustering across diverse datasets. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.18.571953. [PMID: 38187667 PMCID: PMC10769222 DOI: 10.1101/2023.12.18.571953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Clustering analysis is widely used to group objects by similarity, but for complex datasets such as those produced by single-cell analysis, the currently available clustering methods are limited by accuracy, robustness, ease of use, and interpretability. To address these limitations, we developed an ensemble clustering method with hyperparameter randomization that outperforms other methods across a broad range of single-cell and synthetic datasets, without the need for manual hyperparameter selection. In addition to hard cluster labels, it also outputs soft cluster memberships to characterize continuum-like regions and per cell overlap scores to quantify the uncertainty in cluster assignment. We demonstrate the improved clustering interpretability from these features by tracing the intermediate stages between handwritten digits in the MNIST dataset, and between tanycyte subpopulations in the hypothalamus. This approach improves the quality of clustering and subsequent downstream analyses for single-cell datasets, and may also prove useful in other fields of data analysis.
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Affiliation(s)
- Sarah M. Goggin
- Neuroscience Graduate Program, School of Medicine, University of Virginia, Charlottesville, VA 22902
| | - Eli R. Zunder
- Neuroscience Graduate Program, School of Medicine, University of Virginia, Charlottesville, VA 22902
- Department of Biomedical Engineering, School of Engineering, University of Virginia, Charlottesville, VA 22902
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10
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Liu SM, Ifebi B, Johnson F, Xu A, Ho J, Yang Y, Schwartz G, Jo YH, Chua S. The gut signals to AGRP-expressing cells of the pituitary to control glucose homeostasis. J Clin Invest 2023; 133:e164185. [PMID: 36787185 PMCID: PMC10065075 DOI: 10.1172/jci164185] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 02/07/2023] [Indexed: 02/15/2023] Open
Abstract
Glucose homeostasis can be improved after bariatric surgery, which alters bile flow and stimulates gut hormone secretion, particularly FGF15/19. FGFR1 expression in AGRP-expressing cells is required for bile acids' ability to improve glucose control. We show that the mouse Agrp gene has 3 promoter/enhancer regions that direct transcription of each of their own AGRP transcripts. One of these Agrp promoters/enhancers, Agrp-B, is regulated by bile acids. We generated an Agrp-B knockin FLP/knockout allele. AGRP-B-expressing cells are found in endocrine cells of the pars tuberalis and coexpress diacylglycerol lipase B - an endocannabinoid biosynthetic enzyme - distinct from pars tuberalis thyrotropes. AGRP-B expression is also found in the folliculostellate cells of the pituitary's anterior lobe. Mice without AGRP-B were protected from glucose intolerance induced by high-fat feeding but not from excess weight gain. Chemogenetic inhibition of AGRP-B cells improved glucose tolerance by enhancing glucose-stimulated insulin secretion. Inhibition of the AGRP-B cells also caused weight loss. The improved glucose tolerance and reduced body weight persisted up to 6 weeks after cessation of the DREADD-mediated inhibition, suggesting the presence of a biological switch for glucose homeostasis that is regulated by long-term stability of food availability.
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Affiliation(s)
| | | | | | | | | | - Yunlei Yang
- Department of Medicine
- Department of Neuroscience, and
| | - Gary Schwartz
- Department of Medicine
- Department of Neuroscience, and
| | - Young Hwan Jo
- Department of Medicine
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, New York, USA
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11
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Haddad-Tóvolli R, Morari J, Barbizan R, Bóbbo VC, Carraro RS, Solon C, Dragano NR, Torsoni MA, Araujo EP, Velloso LA. Maternal obesity damages the median eminence blood-brain barrier structure and function in the progeny: the beneficial impact of cross-fostering by lean mothers. Am J Physiol Endocrinol Metab 2023; 324:E154-E166. [PMID: 36598900 DOI: 10.1152/ajpendo.00268.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Maternal obesity is an important risk factor for obesity, cardiovascular, and metabolic diseases in the offspring. Studies have shown that it leads to hypothalamic inflammation in the progeny, affecting the function of neurons regulating food intake and energy expenditure. In adult mice fed a high-fat diet, one of the hypothalamic abnormalities that contribute to the development of obesity is the damage of the blood-brain barrier (BBB) at the median eminence-arcuate nucleus (ME-ARC) interface; however, how the hypothalamic BBB is affected in the offspring of obese mothers requires further investigation. Here, we used confocal and transmission electron microscopy, transcript expression analysis, glucose tolerance testing, and a cross-fostering intervention to determine the impact of maternal obesity and breastfeeding on BBB integrity at the ME-ARC interface. The offspring of obese mothers were born smaller; conversely, at weaning, they presented larger body mass and glucose intolerance. In addition, maternal obesity-induced structural and functional damage of the offspring's ME-ARC BBB. By a cross-fostering intervention, some of the defects in barrier integrity and metabolism seen during development in an obesogenic diet were recovered. The offspring of obese dams breastfed by lean dams presented a reduction of body mass and glucose intolerance as compared to the offspring continuously exposed to an obesogenic environment during intrauterine and perinatal life; this was accompanied by partial recovery of the anatomical structure of the ME-ARC interface, and by the normalization of transcript expression of genes coding for hypothalamic neurotransmitters involved in energy balance and BBB integrity. Thus, maternal obesity promotes structural and functional damage of the hypothalamic BBB, which is, in part, reverted by lactation by lean mothers.NEW & NOTEWORTHY Maternal dietary habits directly influence offspring health. In this study, we aimed at determining the impact of maternal obesity on BBB integrity. We show that DIO offspring presented a leakier ME-BBB, accompanied by changes in the expression of transcripts encoding for endothelial and tanycytic proteins, as well as of hypothalamic neuropeptides. Breastfeeding in lean dams was sufficient to protect the offspring from ME-BBB disruption, providing a preventive strategy of nutritional intervention during early life.
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Affiliation(s)
- Roberta Haddad-Tóvolli
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas, Campinas, Brazil
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Joseane Morari
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas, Campinas, Brazil
| | - Roberta Barbizan
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas, Campinas, Brazil
| | - Vanessa C Bóbbo
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas, Campinas, Brazil
| | - Rodrigo S Carraro
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas, Campinas, Brazil
- Center for Anatomy Studies, University San Francisco (USF), Bragança Paulista, Brazil
| | - Carina Solon
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas, Campinas, Brazil
| | - Nathalia R Dragano
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas, Campinas, Brazil
| | - Márcio A Torsoni
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, State University of Campinas, Campinas, Limeira, Brazil
| | - Eliana P Araujo
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas, Campinas, Brazil
- School of Nursing, University of Campinas, Campinas, Brazil
| | - Licio A Velloso
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University of Campinas, Campinas, Brazil
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12
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Lopez-Rodriguez D, Rohrbach A, Lanzillo M, Gervais M, Croizier S, Langlet F. Ontogeny of ependymoglial cells lining the third ventricle in mice. Front Endocrinol (Lausanne) 2023; 13:1073759. [PMID: 36686420 PMCID: PMC9849764 DOI: 10.3389/fendo.2022.1073759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/02/2022] [Indexed: 01/07/2023] Open
Abstract
Introduction During hypothalamic development, the germinative neuroepithelium gives birth to diverse neural cells that regulate numerous physiological functions in adulthood. Methods Here, we studied the ontogeny of ependymal cells in the mouse mediobasal hypothalamus using the BrdU approach and publicly available single-cell RNAseq datasets. Results We observed that while typical ependymal cells are mainly produced at E13, tanycyte birth depends on time and subtypes and lasts up to P8. Typical ependymocytes and β tanycytes are the first to arise at the top and bottom of the dorsoventral axis around E13, whereas α tanycytes emerge later in development, generating an outside-in dorsoventral gradient along the third ventricle. Additionally, α tanycyte generation displayed a rostral-to-caudal pattern. Finally, tanycytes mature progressively until they reach transcriptional maturity between P4 and P14. Discussion Altogether, this data shows that ependyma generation differs in time and distribution, highlighting the heterogeneity of the third ventricle.
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Affiliation(s)
- David Lopez-Rodriguez
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Antoine Rohrbach
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Marc Lanzillo
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Manon Gervais
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Sophie Croizier
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Fanny Langlet
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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13
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Hoermann R, Pekker MJ, Midgley JEM, Dietrich JW. The role of supporting and disruptive mechanisms of FT3 homeostasis in regulating the hypothalamic-pituitary-thyroid axis. Ther Adv Endocrinol Metab 2023; 14:20420188231158163. [PMID: 36936128 PMCID: PMC10017955 DOI: 10.1177/20420188231158163] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 12/18/2022] [Indexed: 03/18/2023] Open
Abstract
BACKGROUND Thyroid hormones are controlled by the hypothalamic-pituitary-thyroid (HPT) axis through a complex network of regulatory loops, involving the hormones TRH, TSH, FT4, and FT3. The relationship between TSH and FT4 is widely used for diagnosing thyroid diseases. However, mechanisms of FT3 homeostasis are not well understood. OBJECTIVE We used mathematical modelling to further examine mechanisms that exist in the HPT axis regulation for protecting circulating FT3 levels. METHODS A mathematical model consisting of a system of four coupled first-order parameterized non-linear ordinary differential equations (ODEs) was developed, accounting for the interdependencies between the hormones in the HPT axis regulation. While TRH and TSH feed forward to the pituitary and thyroid, respectively, FT4 and FT3 feed backward to both the pituitary and hypothalamus. Stable equilibrium solutions of the ODE system express homeostasis for a particular variable, such as FT3, if this variable stays in a narrow range while certain other parameter(s) and system variable(s) may vary substantially. RESULTS The model predicts that (1) TSH-feedforward protects FT3 levels if the FT4 production rate declines and (2) combined negative feedback by FT4 and FT3 on both TSH and TRH production rates keeps FT3 levels insensitive to moderate changes in FT4 production rates and FT4 levels. The optimum FT4 and FT3 feedback and TRH and TSH-feedforward ranges that preserve FT3 homeostasis were found by numerical continuation analysis. Model predictions were in close agreement with clinical studies and individual patient examples of hypothyroidism and hyperthyroidism. CONCLUSIONS These findings further extend the concept of HPT axis regulation beyond TSH and FT4 to integrate the more active sister hormone FT3 and mechanisms of FT3 homeostasis. Disruption of homeostatic mechanisms leads to disease. This provides a perspective for novel testable concepts in clinical studies to therapeutically target the disruptive mechanisms.
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Affiliation(s)
| | - Mark J. Pekker
- Mathematical Sciences Department, University of Alabama, Huntsville, AL, USA
| | | | - Johannes W. Dietrich
- Diabetes, Endocrinology and Metabolism Section, Department of Medicine I, St. Josef Hospital, Ruhr University Hospitals, Bochum, Germany
- Diabetes Centre Bochum/Hattingen, Blankenstein Hospital, Hattingen, Germany
- Centre for Diabetes Technology (ZDT), Catholic Hospitals Bochum, Bochum, Germany
- Centre for Rare Endocrine Diseases (ZSEK), Ruhr Center for Rare Diseases (CeSER), Ruhr University of Bochum and Witten/Herdecke University, Bochum, Germany
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14
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Hypothalamic remodeling of thyroid hormone signaling during hibernation in the arctic ground squirrel. Commun Biol 2022; 5:492. [PMID: 35606540 PMCID: PMC9126913 DOI: 10.1038/s42003-022-03431-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 04/29/2022] [Indexed: 12/16/2022] Open
Abstract
Hibernation involves prolonged intervals of profound metabolic suppression periodically interrupted by brief arousals to euthermy, the function of which is unknown. Annual cycles in mammals are timed by a photoperiodically-regulated thyroid-hormone-dependent mechanism in hypothalamic tanycytes, driven by thyrotropin (TSH) in the pars tuberalis (PT), which regulates local TH-converting deiodinases and triggers remodeling of neuroendocrine pathways. We demonstrate that over the course of hibernation in continuous darkness, arctic ground squirrels (Urocitellus parryii) up-regulate the retrograde TSH/Deiodinase/TH pathway, remodel hypothalamic tanycytes, and activate the reproductive axis. Forcing the premature termination of hibernation by warming animals induced hypothalamic deiodinase expression and the accumulation of secretory granules in PT thyrotrophs and pituitary gonadotrophs, but did not further activate the reproductive axis. We suggest that periodic arousals may allow for the transient activation of hypothalamic thyroid hormone signaling, cellular remodeling, and re-programming of brain circuits in preparation for the short Arctic summer. Arctic ground squirrels hibernating in darkness activate the pars tuberalis - hypothalamus thyroid hormone signaling pathway, remodel hypothalamic tanycytes, and activate the reproductive axis.
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15
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Sullivan AI, Potthoff MJ, Flippo KH. Tany-Seq: Integrated Analysis of the Mouse Tanycyte Transcriptome. Cells 2022; 11:1565. [PMID: 35563871 PMCID: PMC9104898 DOI: 10.3390/cells11091565] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [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: 04/27/2022] [Accepted: 05/04/2022] [Indexed: 02/01/2023] Open
Abstract
The ability to maintain energy homeostasis is necessary for survival. Recently, an emerging role for ependymogial cells, which line the third ventricle in the hypothalamus in the regulation of energy homeostasis, has been appreciated. These cells are called tanycytes and are physically at the interface of brain communication with peripheral organs and have been proposed to mediate the transport of circulating hormones from the third ventricle into the parenchyma of the hypothalamus. Despite the important role tanycytes have been proposed to play in mediating communication from the periphery to the brain, we understand very little about the ontology and function of these cells due to their limited abundance and lack of ability to genetically target this cell population reliably. To overcome these hurdles, we integrated existing hypothalamic single cell RNA sequencing data, focusing on tanycytes, to allow for more in-depth characterization of tanycytic cell types and their putative functions. Overall, we expect this dataset to serve as a resource for the research community.
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Affiliation(s)
- Andrew I. Sullivan
- Department of Neuroscience and Pharmacology, College of Medicine, University of Iowa Carver, Iowa City, IA 52242, USA; (A.I.S.); (M.J.P.)
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Matthew J. Potthoff
- Department of Neuroscience and Pharmacology, College of Medicine, University of Iowa Carver, Iowa City, IA 52242, USA; (A.I.S.); (M.J.P.)
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Department of Veterans Affairs Medical Center, Iowa City, IA 52242, USA
| | - Kyle H. Flippo
- Department of Neuroscience and Pharmacology, College of Medicine, University of Iowa Carver, Iowa City, IA 52242, USA; (A.I.S.); (M.J.P.)
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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16
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Freeman AK, Glendining KA, Jasoni CL. Developmental genes controlling neural circuit formation are expressed in the early postnatal hypothalamus and cellular lining of the third ventricle. J Neuroendocrinol 2021; 33:e13020. [PMID: 34423876 DOI: 10.1111/jne.13020] [Citation(s) in RCA: 4] [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: 02/01/2021] [Revised: 07/20/2021] [Accepted: 07/27/2021] [Indexed: 02/07/2023]
Abstract
The arcuate nucleus of the hypothalamus is central in the regulation of body weight homeostasis through its ability to sense peripheral metabolic signals and relay them, through neural circuits, to other brain areas, ultimately affecting physiological and behavioural changes. The early postnatal development of these neural circuits is critical for normal body weight homeostasis, such that perturbations during this critical period can lead to obesity. The role for peripheral regulators of body weight homeostasis, including leptin, insulin and ghrelin, in this postnatal development is well described, yet some of the fundamental processes underpinning axonal and dendritic growth remain unclear. Here, we hypothesised that molecules known to regulate axonal and dendritic growth processes in other areas of the developing brain would be expressed in the postnatal arcuate nucleus and/or target nuclei where they would function to mediate the development of this circuitry. Using state-of-the-art RNAscope® technology, we have revealed the expression patterns of genes encoding Dcc/Netrin-1, Robo1/Slit1 and Fzd5/Wnt5a receptor/ligand pairs in the early postnatal mouse hypothalamus. We found that individual genes had unique expression patterns across developmental time in the arcuate nucleus, paraventricular nucleus of the hypothalamus, ventromedial nucleus of the hypothalamus, dorsomedial nucleus of the hypothalamus, median eminence and, somewhat unexpectedly, the third ventricle epithelium. These observations indicate a number of new molecular players in the development of neural circuits regulating body weight homeostasis, as well as novel molecular markers of tanycyte heterogeneity.
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Affiliation(s)
- Alice Katherine Freeman
- Centre for Neuroendocrinology, Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Kelly A Glendining
- Centre for Neuroendocrinology, Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Christine L Jasoni
- Centre for Neuroendocrinology, Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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Wang J, Beecher K. TSPO: an emerging role in appetite for a therapeutically promising biomarker. Open Biol 2021; 11:210173. [PMID: 34343461 PMCID: PMC8331234 DOI: 10.1098/rsob.210173] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
There is accumulating evidence that an obesogenic Western diet causes neuroinflammatory damage to the brain, which then promotes further appetitive behaviour. Neuroinflammation has been extensively studied by analysing the translocator protein of 18 kDa (TSPO), a protein that is upregulated in the inflamed brain following a damaging stimulus. As a result, there is a rich supply of TSPO-specific agonists, antagonists and positron emission tomography ligands. One TSPO ligand, etifoxine, is also currently used clinically for the treatment of anxiety with a minimal side-effect profile. Despite the neuroinflammatory pathogenesis of diet-induced obesity, and the translational potential of targeting TSPO, there is sparse literature characterizing the effect of TSPO on appetite. Therefore, in this review, the influence of TSPO on appetite is discussed. Three putative mechanisms for TSPO's appetite-modulatory effect are then characterized: the TSPO–allopregnanolone–GABAAR signalling axis, glucosensing in tanycytes and association with the synaptic protein RIM-BP1. We highlight that, in addition to its plethora of functions, TSPO is a regulator of appetite. This review ultimately suggests that the appetite-modulating function of TSPO should be further explored due to its potential therapeutic promise.
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Affiliation(s)
- Joshua Wang
- Addiction Neuroscience and Obesity Laboratory, School of Clinical Sciences, Faculty of Health, Translational Research Institute, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Kate Beecher
- Addiction Neuroscience and Obesity Laboratory, School of Clinical Sciences, Faculty of Health, Translational Research Institute, Queensland University of Technology, Brisbane, Queensland, Australia
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18
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Ursem SR, Diepenbroek C, Bacic V, Unmehopa UA, Eggels L, Maya‐Monteiro CM, Heijboer AC, la Fleur SE. Localization of fibroblast growth factor 23 protein in the rat hypothalamus. Eur J Neurosci 2021; 54:5261-5271. [PMID: 34184338 PMCID: PMC8456796 DOI: 10.1111/ejn.15375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 11/29/2022]
Abstract
Fibroblast growth factor 23 (FGF23) is an endocrine growth factor and known to play a pivotal role in phosphate homeostasis. Interestingly, several studies point towards a function of FGF23 in the hypothalamus. FGF23 classically activates the FGF receptor 1 in the presence of the co-receptor αKlotho, of both gene expression in the brain was previously established. However, studies on gene and protein expression of FGF23 in the brain are scarce and have been inconsistent. Therefore, our aim was to localise FGF23 gene and protein expression in the rat brain with focus on the hypothalamus. Also, we investigated the protein expression of αKlotho. Adult rat brains were used to localise and visualise FGF23 and αKlotho protein in the hypothalamus by immunofluorescence labelling. Furthermore, western blots were used for assessing hypothalamic FGF23 protein expression. FGF23 gene expression was investigated by qPCR in punches of the arcuate nucleus, lateral hypothalamus, paraventricular nucleus, choroid plexus, ventrolateral thalamic nucleus and the ventromedial hypothalamus. Immunoreactivity for FGF23 and αKlotho protein was found in the hypothalamus, third ventricle lining and the choroid plexus. Western blot analysis of the hypothalamus confirmed the presence of FGF23. Gene expression of FGF23 was not detected, suggesting that the observed FGF23 protein is not brain-derived. Several FGF receptors are known to be present in the brain. Therefore, we conclude that the machinery for FGF23 signal transduction is present in several brain areas, indeed suggesting a role for FGF23 in the brain.
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Affiliation(s)
- Stan R. Ursem
- Endocrine Laboratory, Department of Clinical Chemistry, Amsterdam Gastroenterology & MetabolismAmsterdam UMC, Vrije Universiteit Amsterdam and University of AmsterdamAmsterdamThe Netherlands
| | - Charlene Diepenbroek
- Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam NeuroscienceAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward Group, Netherlands Institute for NeuroscienceAn Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Vesna Bacic
- Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam NeuroscienceAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward Group, Netherlands Institute for NeuroscienceAn Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Unga A. Unmehopa
- Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam NeuroscienceAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward Group, Netherlands Institute for NeuroscienceAn Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Leslie Eggels
- Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam NeuroscienceAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward Group, Netherlands Institute for NeuroscienceAn Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Clarissa M. Maya‐Monteiro
- Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam NeuroscienceAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward Group, Netherlands Institute for NeuroscienceAn Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
- Laboratory of Immunopharmacology, Oswaldo Cruz Institute (IOC)Oswaldo Cruz Foundation (FIOCRUZ)Rio de JaneiroBrazil
| | - Annemieke C. Heijboer
- Endocrine Laboratory, Department of Clinical Chemistry, Amsterdam Gastroenterology & MetabolismAmsterdam UMC, Vrije Universiteit Amsterdam and University of AmsterdamAmsterdamThe Netherlands
| | - Susanne E. la Fleur
- Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam NeuroscienceAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward Group, Netherlands Institute for NeuroscienceAn Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
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19
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Rohrbach A, Caron E, Dali R, Brunner M, Pasquettaz R, Kolotuev I, Santoni F, Thorens B, Langlet F. Ablation of glucokinase-expressing tanycytes impacts energy balance and increases adiposity in mice. Mol Metab 2021; 53:101311. [PMID: 34325016 PMCID: PMC8379510 DOI: 10.1016/j.molmet.2021.101311] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 07/20/2021] [Indexed: 01/06/2023] Open
Abstract
Objectives Glucokinase (GCK) is critical for glucosensing. In rats, GCK is expressed in hypothalamic tanycytes and appears to play an essential role in feeding behavior. In this study, we investigated the distribution of GCK-expressing tanycytes in mice and their role in the regulation of energy balance. Methods In situ hybridization, reporter gene assay, and immunohistochemistry were used to assess GCK expression along the third ventricle in mice. To evaluate the impact of GCK-expressing tanycytes on arcuate neuron function and mouse physiology, Gck deletion along the ventricle was achieved using loxP/Cre recombinase technology in adult mice. Results GCK expression was low along the third ventricle, but detectable in tanycytes facing the ventromedial arcuate nucleus from bregma −1.5 to −2.2. Gck deletion induced the death of this tanycyte subgroup through the activation of the BAD signaling pathway. The ablation of GCK-expressing tanycytes affected different aspects of energy balance, leading to an increase in adiposity in mice. This phenotype was systematically associated with a defect in NPY neuron function. In contrast, the regulation of glucose homeostasis was mostly preserved, except for glucoprivic responses. Conclusions This study describes the role of GCK in tanycyte biology and highlights the impact of tanycyte loss on the regulation of energy balance. vmARH tanycytes express glucokinase. Glucokinase deletion in tanycytes induces cell death. Ablation of vmARH tanycytes alters energy balance and adiposity. Ablation of vmARH tanycytes alters NPY neuron function.
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Affiliation(s)
- Antoine Rohrbach
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland; Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Emilie Caron
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S, 1172, Lille, France
| | - Rafik Dali
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Maxime Brunner
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Faculty of Biology and Medicine, 1011, Lausanne, Switzerland
| | - Roxane Pasquettaz
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Irina Kolotuev
- Electron Microscopy Facility, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Federico Santoni
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Faculty of Biology and Medicine, 1011, Lausanne, Switzerland
| | - Bernard Thorens
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Fanny Langlet
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland; Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
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Abstract
Thyroid hormone is essential for brain development and brain function in the adult. During development, thyroid hormone acts in a spatial and temporal-specific manner to regulate the expression of genes essential for normal neural cell differentiation, migration, and myelination. In the adult brain, thyroid hormone is important for maintaining normal brain function. Thyroid hormone excess, hyperthyroidism, and thyroid hormone deficiency, hypothyroidism, are associated with disordered brain function, including depression, memory loss, impaired cognitive function, irritability, and anxiety. Adequate thyroid hormone levels are required for normal brain function. Thyroid hormone acts through a cascade of signaling components: activation and inactivation by deiodinase enzymes, thyroid hormone membrane transporters, and nuclear thyroid hormone receptors. Additionally, the hypothalamic-pituitary-thyroid axis, with negative feedback of thyroid hormone on thyrotropin-releasing hormone (TRH) and thyroid-stimulating hormone (TSH) secretion, regulates serum thyroid hormone levels in a narrow range. Animal and human studies have shown both systemic and local reduction in thyroid hormone availability in neurologic disease and after brain trauma. Treatment with thyroid hormone and selective thyroid hormone analogs has resulted in a reduction in injury and improved recovery. This article will describe the thyroid hormone signal transduction pathway in the brain and the role of thyroid hormone in the aging brain, neurologic diseases, and the protective role when administered after traumatic brain injury. © 2021 American Physiological Society. Compr Physiol 11:1-21, 2021.
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Affiliation(s)
- Yan-Yun Liu
- Department of Medicine, VA Greater Los Angeles Healthcare System, Los Angeles, California, USA.,Departments of Medicine and Physiology, Endocrinology, Diabetes and Metabolism Division, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Gregory A Brent
- Department of Medicine, VA Greater Los Angeles Healthcare System, Los Angeles, California, USA.,Departments of Medicine and Physiology, Endocrinology, Diabetes and Metabolism Division, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
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21
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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: 29] [Impact Index Per Article: 9.7] [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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Bolborea M, Langlet F. What is the physiological role of hypothalamic tanycytes in metabolism? Am J Physiol Regul Integr Comp Physiol 2021; 320:R994-R1003. [PMID: 33826442 DOI: 10.1152/ajpregu.00296.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In vertebrates, the energy balance process is tightly controlled by complex neural circuits that sense metabolic signals and adjust food intake and energy expenditure in line with the physiological requirements of optimal conditions. Within neural networks controlling energy balance, tanycytes are peculiar ependymoglial cells that are nowadays recognized as multifunctional players in the metabolic hypothalamus. However, the physiological function of hypothalamic tanycytes remains unclear, creating a number of ambiguities in the field. Here, we review data accumulated over the years that demonstrate the physiological function of tanycytes in the maintenance of metabolic homeostasis, opening up new research avenues. The presumed involvement of tanycytes in the pathophysiology of metabolic disorders and age-related neurodegenerative diseases will be finally discussed.
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Affiliation(s)
- Matei Bolborea
- Central and Peripheral Mechanisms of Neurodegeneration, INSERM U1118, Université de Strasbourg, Strasbourg, France.,School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Fanny Langlet
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
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Frare C, Drew KL. Seasonal changes in adenosine kinase in tanycytes of the Arctic ground squirrel (Urocitellus parryii). J Chem Neuroanat 2021; 113:101920. [PMID: 33515665 PMCID: PMC8091519 DOI: 10.1016/j.jchemneu.2021.101920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 12/29/2020] [Accepted: 01/18/2021] [Indexed: 10/22/2022]
Abstract
Hibernation is a seasonal strategy to conserve energy, characterized by modified thermoregulation, an increase in sleep pressure and drastic metabolic changes. Glial cells such as astrocytes and tanycytes are the brain metabolic sensors, but it remains unknown whether they contribute to seasonal expression of hibernation. The onset of hibernation is controlled by an undefined endogenous circannual rhythm in which adenosine plays a role through the activation of the A1 adenosine receptor (A1AR). Seasonal changes in brain levels of adenosine may contribute to an increase in A1AR sensitivity leading to the onset of hibernation. The primary regulator of extracellular adenosine concentration is adenosine kinase, which is located in astrocytes. Using immunohistochemistry to localize and quantify adenosine kinase in Arctic ground squirrels' brain collected during different seasons, we report lower expression of adenosine kinase in the third ventricle tanycytes in winter compared to summer; a similar change was not seen in astrocytes. Moreover, for the first time, we describe adenosine kinase expression in tanycyte cell bodies in the hypothalamus and in the area postrema, both brain regions involved in energy homeostasis. Next we describe seasonal changes in tanycyte morphology in the hypothalamus. Although still speculative, our findings contribute to a model whereby adenosine kinase in tanycytes regulates seasonal changes in extracellular concentration of adenosine underling the seasonal expression of hibernation.
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Affiliation(s)
- C Frare
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, 900 Yukon Drive Rm. 194, Fairbanks, AK 99775-6160, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, AK 99775-7000 USA
| | - K L Drew
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, 900 Yukon Drive Rm. 194, Fairbanks, AK 99775-6160, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, AK 99775-7000 USA.
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24
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Frare C, Williams CT, Drew KL. Thermoregulation in hibernating mammals: The role of the "thyroid hormones system". Mol Cell Endocrinol 2021; 519:111054. [PMID: 33035626 PMCID: PMC8091518 DOI: 10.1016/j.mce.2020.111054] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 07/15/2020] [Accepted: 10/04/2020] [Indexed: 12/19/2022]
Abstract
Hibernation is a unique evolutionary adaptation to conserve energy. During the pre-hibernation (i.e. fall) season, a progressive decline in core body temperature and further decrease in metabolism underlie a seasonal modulation in thermoregulation. The onset of hibernation requires marked changes in thermoregulatory attributes including adjustment in body temperature and tissue specific increases in thermogenic capacity. The hibernation season is characterized by a regulated suppression in thermogenesis allowing the onset of torpor interrupted by periodic activation of thermogenesis to sustain interbout arousals. Thyroid hormones are known to regulate both body temperature and metabolism, and for this reason, the hypothalamic-pituitary-thyroid axis and thyroid hormones have been investigated as modulators of thermogenesis in the phenomenon of hibernation, but the mechanisms remain poorly understood. In this review, we present an overview of what is known about the thermogenic roles of thyroid hormones in hibernating species across seasons and within the hibernating season (torpor-interbout arousal cycle). Overall, the hypothalamic-pituitary-thyroid axis and thyroid hormones play a role in the pre-hibernation season to enhance thermogenic capacity. During hibernation, thermogenesis is attenuated at the level of sympathetic premotor neurons within the raphe pallidus and by deiodinase expression in the hypothalamus. Further, as recent work highlights the direct effect of thyroid hormones within the central nervous system in activating thermogenesis, we speculate how similar mechanisms may occur in hibernating species to modulate thermogenesis across seasons and to sustain interbout arousals. However, further experiments are needed to elucidate the role of thyroid hormones in hibernation, moving towards the understanding that thyroid hormones metabolism, transport and availability within tissues may be the most telling indicator of thyroid status.
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Affiliation(s)
- C Frare
- Department of Chemistry and Biochemistry University of Alaska Fairbanks, Fairbanks, AK, 99775, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks 2140 Koyukuk Drive, Fairbanks, AK, 99775, USA
| | - Cory T Williams
- Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks 2140 Koyukuk Drive, Fairbanks, AK, 99775, USA; Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
| | - Kelly L Drew
- Department of Chemistry and Biochemistry University of Alaska Fairbanks, Fairbanks, AK, 99775, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks 2140 Koyukuk Drive, Fairbanks, AK, 99775, USA.
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25
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Pasquettaz R, Kolotuev I, Rohrbach A, Gouelle C, Pellerin L, Langlet F. Peculiar protrusions along tanycyte processes face diverse neural and nonneural cell types in the hypothalamic parenchyma. J Comp Neurol 2020; 529:553-575. [PMID: 32515035 PMCID: PMC7818493 DOI: 10.1002/cne.24965] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 05/22/2020] [Accepted: 05/27/2020] [Indexed: 12/15/2022]
Abstract
Tanycytes are highly specialized ependymal cells that line the bottom and the lateral walls of the third ventricle. In contact with the cerebrospinal fluid through their cell bodies, they send processes into the arcuate nucleus, the ventromedial nucleus, and the dorsomedial nucleus of the hypothalamus. In the present work, we combined transgenic and immunohistochemical approaches to investigate the neuroanatomical associations between tanycytes and neural cells present in the hypothalamic parenchyma, in particular in the arcuate nucleus. The specific expression of tdTomato in tanycytes first allowed the observation of peculiar subcellular protrusions along tanycyte processes and at their endfeet such as spines, swelling, en passant boutons, boutons, or claws. Interestingly, these protrusions contact different neural cells in the brain parenchyma including blood vessels and neurons, and in particular NPY and POMC neurons in the arcuate nucleus. Using both fluorescent and electron microscopy, we finally observed that these tanycyte protrusions contain ribosomes, mitochondria, diverse vesicles, and transporters, suggesting dense tanycyte/neuron and tanycyte/blood vessel communications. Altogether, our results lay the neuroanatomical basis for tanycyte/neural cell interactions, which will be useful to further understand cell-to-cell communications involved in the regulation of neuroendocrine functions.
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Affiliation(s)
- Roxane Pasquettaz
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Irina Kolotuev
- Electron Microscopy Facility, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Antoine Rohrbach
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Cathy Gouelle
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Luc Pellerin
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.,Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536 CNRS, LabEx TRAIL-IBIO, Université de Bordeaux, Bordeaux Cedex, France.,Inserm U1082, Universite de Poitiers, Poitiers Cedex, France
| | - Fanny Langlet
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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Hypothalamic tanycytes generate acute hyperphagia through activation of the arcuate neuronal network. Proc Natl Acad Sci U S A 2020; 117:14473-14481. [PMID: 32513737 PMCID: PMC7322081 DOI: 10.1073/pnas.1919887117] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Tanycytes are nutrient-sensing cells that line the third ventricle within the hypothalamus. The role of tanycytes in the regulation of food intake has not been documented. Indeed, the mechanistic link between nutrient concentrations in the CSF and activation of neurons responsible for the regulation of food intake, such as orexigenic (NPY/AgRP) or anorexigenic (POMC) cells, is not yet clear. Here, we demonstrate that tanycytes, engineered to express channelrhodopsin, can activate arcuate neurons to induce acute hyperphagia when activated by light. These data provide further evidence that tanycytes are an integral link between CSF nutrients and the hypothalamic neuronal networks that regulate appetite and energy balance. Hypothalamic tanycytes are chemosensitive glial cells that contact the cerebrospinal fluid in the third ventricle and send processes into the hypothalamic parenchyma. To test whether they can activate neurons of the arcuate nucleus, we targeted expression of a Ca2+-permeable channelrhodopsin (CatCh) specifically to tanycytes. Activation of tanycytes ex vivo depolarized orexigenic (neuropeptide Y/agouti-related protein; NPY/AgRP) and anorexigenic (proopiomelanocortin; POMC) neurons via an ATP-dependent mechanism. In vivo, activation of tanycytes triggered acute hyperphagia only in the fed state during the inactive phase of the light–dark cycle.
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Hoermann R, Pekker MJ, Midgley JEM, Larisch R, Dietrich JW. Triiodothyronine secretion in early thyroid failure: The adaptive response of central feedforward control. Eur J Clin Invest 2020; 50:e13192. [PMID: 31815292 DOI: 10.1111/eci.13192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 10/06/2019] [Accepted: 12/02/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND Defined by thyroid-pituitary feedback control, clinical diagnosis of hypothyroidism and hyperthyroidism has become synonymous with TSH measurement. We combined in silico analysis and in vivo data to explore the central influences on thyroidal T3 production. MATERIALS & METHODS A system of five coupled first-order nonlinear parameterised ordinary differential equations (ODEs) is used to model the feedback control of TSH and TRH by thyroid hormones together with the feedforward control of thyroidal T3 secretion and enzymatic T4-T3 conversion. Dependencies of the stable equilibrium solutions of this ODE system, that is the homeostasis of the underlying physiological process, on the system parameters were investigated whether they accounted for clinical observations. RESULTS During the modelled transition to hypothyroidism, central control imposed an increasing influence in maintaining serum FT3 levels, compared to peripheral conversion efficiency. Numerical continuation analysis revealed dependencies of T3 production on different elements of TSH feedforward control. While T4-T3 conversion provided the main T3 source in euthyroidism, this was overtaken by increasing glandular T3 secretion when thyroid reserve declined. The computational results were in good agreement with data from untreated patients with autoimmune thyroiditis. CONCLUSIONS Dependencies revealed in the expression of control differ in thyroid health and disease, using a physiologically based mathematical model of combined feedback-feedforward control of the hypothalamic-pituitary-thyroid regulation. Strong T3-protective mechanisms of the control system emerge with declining thyroid function, when glandular T3 secretion becomes increasingly influential over conversion efficiency. This has wide-ranging implications for the utility of TSH in clinical decision-making.
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Affiliation(s)
- Rudolf Hoermann
- Department for Nuclear Medicine, Klinikum Lüdenscheid, Lüdenscheid, Germany
| | - Mark J Pekker
- Mathematical Sciences Department, University of Alabama, Huntsville, AL, USA
| | | | - Rolf Larisch
- Department for Nuclear Medicine, Klinikum Lüdenscheid, Lüdenscheid, Germany
| | - Johannes W Dietrich
- Medical Department I, Endocrinology and Diabetology, Bergmannsheil University Hospitals, Ruhr University of Bochum, Bochum, Germany.,Ruhr Center for Rare Diseases (CeSER), Ruhr University of Bochum and Witten/Herdecke University, Bochum, Germany
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28
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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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Rodríguez-Rodríguez A, Lazcano I, Sánchez-Jaramillo E, Uribe RM, Jaimes-Hoy L, Joseph-Bravo P, Charli JL. Tanycytes and the Control of Thyrotropin-Releasing Hormone Flux Into Portal Capillaries. Front Endocrinol (Lausanne) 2019; 10:401. [PMID: 31293518 PMCID: PMC6603095 DOI: 10.3389/fendo.2019.00401] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/06/2019] [Indexed: 12/17/2022] Open
Abstract
Central and peripheral mechanisms that modulate energy intake, partition and expenditure determine energy homeostasis. Thyroid hormones (TH) regulate energy expenditure through the control of basal metabolic rate and thermogenesis; they also modulate food intake. TH concentrations are regulated by the hypothalamus-pituitary-thyroid (HPT) axis, and by transport and metabolism in blood and target tissues. In mammals, hypophysiotropic thyrotropin-releasing hormone (TRH) neurons of the paraventricular nucleus of the hypothalamus integrate energy-related information. They project to the external zone of the median eminence (ME), a brain circumventricular organ rich in neuron terminal varicosities and buttons, tanycytes, other glial cells and capillaries. These capillary vessels form a portal system that links the base of the hypothalamus with the anterior pituitary. Tanycytes of the medio-basal hypothalamus express a repertoire of proteins involved in transport, sensing, and metabolism of TH; among them is type 2 deiodinase, a source of 3,3',5-triiodo-L-thyronine necessary for negative feedback on TRH neurons. Tanycytes subtypes are distinguished by position and phenotype. The end-feet of β2-tanycytes intermingle with TRH varicosities and terminals in the external layer of the ME and terminate close to the ME capillaries. Besides type 2 deiodinase, β2-tanycytes express the TRH-degrading ectoenzyme (TRH-DE); this enzyme likely controls the amount of TRH entering portal vessels. TRH-DE is rapidly upregulated by TH, contributing to TH negative feedback on HPT axis. Alterations in energy balance also regulate the expression and activity of TRH-DE in the ME, making β2-tanycytes a hub for energy-related regulation of HPT axis activity. β2-tanycytes also express TRH-R1, which mediates positive effects of TRH on TRH-DE activity and the size of β2-tanycyte end-feet contacts with the basal lamina adjacent to ME capillaries. These end-feet associations with ME capillaries, and TRH-DE activity, appear to coordinately control HPT axis activity. Thus, down-stream of neuronal control of TRH release by action potentials arrival in the external layer of the median eminence, imbricated intercellular processes may coordinate the flux of TRH into the portal capillaries. In conclusion, β2-tanycytes appear as a critical cellular element for the somatic and post-secretory control of TRH flux into portal vessels, and HPT axis regulation in mammals.
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Affiliation(s)
- Adair Rodríguez-Rodríguez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Iván Lazcano
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Edith Sánchez-Jaramillo
- Laboratorio de Neuroendocrinología Molecular, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Rosa María Uribe
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Lorraine Jaimes-Hoy
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Patricia Joseph-Bravo
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Jean-Louis Charli
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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