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Barahona MJ, Ferrada L, Vera M, Nualart F. Tanycytes release glucose using the glucose-6-phosphatase system during hypoglycemia to control hypothalamic energy balance. Mol Metab 2024; 84:101940. [PMID: 38641253 PMCID: PMC11060961 DOI: 10.1016/j.molmet.2024.101940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/09/2024] [Accepted: 04/09/2024] [Indexed: 04/21/2024] Open
Abstract
OBJECTIVE The liver releases glucose into the blood using the glucose-6-phosphatase (G6Pase) system, a multiprotein complex located in the endoplasmic reticulum (ER). Here, we show for the first time that the G6Pase system is also expressed in hypothalamic tanycytes, and it is required to regulate energy balance. METHODS Using automatized qRT-PCR and immunohistochemical analyses, we evaluated the expression of the G6Pase system. Fluorescent glucose analogue (2-NBDG) uptake was evaluated by 4D live-cell microscopy. Glucose release was tested using a glucose detection kit and high-content live-cell analysis instrument, Incucyte s3. In vivo G6pt knockdown in tanycytes was performed by AAV1-shG6PT-mCherry intracerebroventricular injection. Body weight gain, adipose tissue weight, food intake, glucose metabolism, c-Fos, and neuropeptide expression were evaluated at 4 weeks post-transduction. RESULTS Tanycytes sequester glucose-6-phosphate (G6P) into the ER through the G6Pase system and release glucose in hypoglycaemia via facilitative glucose transporters (GLUTs). Strikingly, in vivo tanycytic G6pt knockdown has a powerful peripheral anabolic effect observed through decreased body weight, white adipose tissue (WAT) tissue mass, and strong downregulation of lipogenesis genes. Selective deletion of G6pt in tanycytes also decreases food intake, c-Fos expression in the arcuate nucleus (ARC), and Npy mRNA expression in fasted mice. CONCLUSIONS The tanycyte-associated G6Pase system is a central mechanism involved in controlling metabolism and energy balance.
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Affiliation(s)
- María José Barahona
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile; Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile; Laboratory of Appetite Physiology (FIDELA), Faculty of Medicine and Sciences, University San Sebastián, Concepción Campus, Concepción, Chile
| | - Luciano Ferrada
- Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile
| | - Matías Vera
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile; Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile
| | - Francisco Nualart
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile; Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile.
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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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Kannangara H, Cullen L, Miyashita S, Korkmaz F, Macdonald A, Gumerova A, Witztum R, Moldavski O, Sims S, Burgess J, Frolinger T, Latif R, Ginzburg Y, Lizneva D, Goosens K, Davies TF, Yuen T, Zaidi M, Ryu V. Emerging roles of brain tanycytes in regulating blood-hypothalamus barrier plasticity and energy homeostasis. Ann N Y Acad Sci 2023; 1525:61-69. [PMID: 37199228 PMCID: PMC10524199 DOI: 10.1111/nyas.15009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Seasonal changes in food intake and adiposity in many animal species are triggered by changes in the photoperiod. These latter changes are faithfully transduced into a biochemical signal by melatonin secreted by the pineal gland. Seasonal variations, encoded by melatonin, are integrated by third ventricular tanycytes of the mediobasal hypothalamus through the detection of the thyroid-stimulating hormone (TSH) released from the pars tuberalis. The mediobasal hypothalamus is a critical brain region that maintains energy homeostasis by acting as an interface between the neural networks of the central nervous system and the periphery to control metabolic functions, including ingestive behavior, energy homeostasis, and reproduction. Among the cells involved in the regulation of energy balance and the blood-hypothalamus barrier (BHB) plasticity are tanycytes. Increasing evidence suggests that anterior pituitary hormones, specifically TSH, traditionally considered to have unitary functions in targeting single endocrine sites, display actions on multiple somatic tissues and central neurons. Notably, modulation of tanycytic TSH receptors seems critical for BHB plasticity in relation to energy homeostasis, but this needs to be proven.
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Affiliation(s)
- Hasni Kannangara
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Liam Cullen
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Sari Miyashita
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Funda Korkmaz
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Anne Macdonald
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Anisa Gumerova
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Ronit Witztum
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Ofer Moldavski
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Steven Sims
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Jocoll Burgess
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Tal Frolinger
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Rauf Latif
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Yelena Ginzburg
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Daria Lizneva
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Ki Goosens
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Terry F. Davies
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Tony Yuen
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Mone Zaidi
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Vitaly Ryu
- Center for Translational Medicine and Pharmacology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine and of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
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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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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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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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