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Duszka K, Wahli W. Enteric Microbiota⁻Gut⁻Brain Axis from the Perspective of Nuclear Receptors. Int J Mol Sci 2018; 19:ijms19082210. [PMID: 30060580 PMCID: PMC6121494 DOI: 10.3390/ijms19082210] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/18/2018] [Accepted: 07/23/2018] [Indexed: 12/12/2022] Open
Abstract
Nuclear receptors (NRs) play a key role in regulating virtually all body functions, thus maintaining a healthy operating body with all its complex systems. Recently, gut microbiota emerged as major factor contributing to the health of the whole organism. Enteric bacteria have multiple ways to influence their host and several of them involve communication with the brain. Mounting evidence of cooperation between gut flora and NRs is already available. However, the full potential of the microbiota interconnection with NRs remains to be uncovered. Herewith, we present the current state of knowledge on the multifaceted roles of NRs in the enteric microbiota–gut–brain axis.
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Affiliation(s)
- Kalina Duszka
- Department of Nutritional Sciences, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
| | - Walter Wahli
- Lee Kong Chian School of Medicine, Nanyang Technological, 11 Mandalay Road, Singapore 308232, Singapore.
- Center for Integrative Genomics, University of Lausanne, Génopode, CH-1015 Lausanne, Switzerland.
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2
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Bernstein HG, Bannier J, Meyer-Lotz G, Steiner J, Keilhoff G, Dobrowolny H, Walter M, Bogerts B. Distribution of immunoreactive glutamine synthetase in the adult human and mouse brain. Qualitative and quantitative observations with special emphasis on extra-astroglial protein localization. J Chem Neuroanat 2014; 61-62:33-50. [PMID: 25058171 DOI: 10.1016/j.jchemneu.2014.07.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 07/14/2014] [Accepted: 07/14/2014] [Indexed: 12/20/2022]
Abstract
Glutamine synthetase catalyzes the ATP-dependent condensation of ammonia and glutamate to form glutamine, thus playing a pivotal role in glutamate and glutamine homoeostasis. Despite a plethora of studies on this enzyme, knowledge about the regional and cellular distribution of this enzyme in human brain is still fragmentary. Therefore, we mapped fourteen post-mortem brains of psychically healthy individuals for the distribution of the glutamine synthetase immunoreactive protein. It was found that glutamine synthetase immunoreactivity is expressed in multiple gray and white matter astrocytes, but also in oligodendrocytes, ependymal cells and certain neurons. Since a possible extra-astrocytic expression of glutamine synthetase is highly controversial, we paid special attention to its appearance in oligodendrocytes and neurons. By double immunolabeling of mouse brain slices and cultured mouse brain cells for glutamine synthetase and cell-type-specific markers we provide evidence that besides astrocytes subpopulations of oligodendrocytes, microglial cells and neurons express glutamine synthetase. Moreover, we show that glutamine synthetase-immunopositive neurons are not randomly distributed throughout human and mouse brain, but represent a subpopulation of nitrergic (i.e. neuronal nitric oxide synthase expressing) neurons. Possible functional implications of an extra-astrocytic localization of glutamine synthetase are discussed.
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Affiliation(s)
- Hans-Gert Bernstein
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany.
| | - Jana Bannier
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Gabriela Meyer-Lotz
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Johann Steiner
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Gerburg Keilhoff
- Institute of Biochemistry and Cell Biology, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Henrik Dobrowolny
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Martin Walter
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany; Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Bernhard Bogerts
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
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3
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Chen CY, Tsai MM, Chi HC, Lin KH. Biological significance of a thyroid hormone-regulated secretome. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2271-84. [PMID: 23429180 DOI: 10.1016/j.bbapap.2013.02.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 02/07/2013] [Accepted: 02/11/2013] [Indexed: 01/18/2023]
Abstract
The thyroid hormone, 3,3,5-triiodo-L-thyronine (T3), modulates several physiological processes, including cellular growth, differentiation, metabolism and proliferation, via interactions with thyroid hormone response elements (TREs) in the regulatory regions of target genes. Several intracellular and extracellular protein candidates are regulated by T3. Moreover, T3-regulated secreted proteins participate in physiological processes or cellular transformation. T3 has been employed as a marker in several disorders, such as cardiovascular disorder in chronic kidney disease, as well as diseases of the liver, immune system, endocrine hormone metabolism and coronary artery. Our group subsequently showed that T3 regulates several tumor-related secretory proteins, leading to cancer progression via alterations in extracellular matrix proteases and tumor-associated signaling pathways in hepatocellular carcinomas. Therefore, elucidation of T3/thyroid hormone receptor-regulated secretory proteins and their underlying mechanisms in cancers should facilitate the identification of novel therapeutic targets. This review provides a detailed summary on the known secretory proteins regulated by T3 and their physiological significance. This article is part of a Special Issue entitled: An Updated Secretome.
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Affiliation(s)
- Cheng-Yi Chen
- Department of Biochemistry, College of Medicine, Chang-Gung University, Taoyuan 333, Taiwan
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4
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Santillo A, Burrone L, Ferrara D, Minucci S, Pinelli C, Chieffi Baccari G. Thyroid hormone receptor-β gene expression in the brain of the frog Pelophylax esculentus: seasonal, hormonal and temperature regulation. Gen Comp Endocrinol 2012; 178:511-8. [PMID: 22841764 DOI: 10.1016/j.ygcen.2012.07.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 07/02/2012] [Accepted: 07/15/2012] [Indexed: 11/25/2022]
Abstract
Thyroid hormone receptor-β (trβ) cDNA was identified in the adult of Pelophylax esculentus (previously: Rana esculenta), a seasonally breeding species, in order to detect spatial brain trβ expression, its levels through the seasons and in response to 6-n-propyl-2-thiouracil, T(4) and T(3) administrations as well as to thermal manipulations. The deduced amino acid sequence of P. esculentus trβ showed a high similarity to the homologous of other vertebrates. By in situ hybridization we found trβ mRNA signal in the anterior preoptic nucleus, the habenulae, the hypothalamic-pituitary region and the ependyma. Brain trβ transcript levels varied through the seasons, and they were well correlated with brain T(4) levels but only partially with T(3) levels. Experimentally-induced hypothyroidism decreased brain trβ expression. The administration of exogenous thyroid hormones increased brain trβ expression, with T(4) appearing more potent than T(3). The experiments of thermal manipulations further strengthen the hypothesis that T(4) is more effective than T(3) in brain trβ regulation. This study also shows that, as in other vertebrates, deiodinase enzymes could modulate trβ expression via thyroid hormone regulation.
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Affiliation(s)
- Alessandra Santillo
- Dipartimento di Scienze della Vita, Seconda Università di Napoli, via Vivaldi 43, 81100 Caserta, Italy
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5
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Shibuya S, Yamamoto T, Itano T. Glial and axonal regeneration following spinal cord injury. Cell Adh Migr 2009; 3:99-106. [PMID: 19372750 DOI: 10.4161/cam.3.1.7372] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Spinal cord injury (SCI) has been regarded clinically as an irreversible damage caused by tissue contusion due to a blunt external force. Past research had focused on the analysis of the pathogenesis of secondary injury that extends from the injury epicenter to the periphery, as well as tissue damage and neural cell death associated with secondary injury. Recent studies, however, have proven that neural stem (progenitor) cells are also present in the brain and spinal cord of adult mammals including humans. Analyses using spinal cord injury models have also demonstrated active dynamics of cells expressing several stem cell markers, and methods aiming at functional reconstruction by promoting the potential self-regeneration capacity of the spinal cord are being explored. Furthermore, reconstruction of the neural circuit requires not only replenishment or regeneration of neural cells but also regeneration of axons. Analysis of the tissue microenvironment after spinal cord injury and research aiming to remove axonal regeneration inhibitors have also made progress. SCI is one of the simplest central nervous injuries, but its pathogenesis is associated with diverse factors, and further studies are required to elucidate these complex interactions in order to achieve spinal cord regeneration and functional reconstruction.
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Affiliation(s)
- Sei Shibuya
- Department of Orthopaedic Surgery, School of Medicine, Kagawa University, Miki-cho, Kagawa, Japan
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6
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Johanson CE, Duncan JA, Stopa EG, Baird A. Enhanced Prospects for Drug Delivery and Brain Targeting by the Choroid Plexus–CSF Route. Pharm Res 2005; 22:1011-37. [PMID: 16028003 DOI: 10.1007/s11095-005-6039-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Accepted: 04/12/2005] [Indexed: 02/07/2023]
Abstract
The choroid plexus (CP), i.e., the blood-cerebrospinal fluid barrier (BCSFB) interface, is an epithelial boundary exploitable for drug delivery to brain. Agents transported from blood to lateral ventricles are convected by CSF volume transmission (bulk flow) to many periventricular targets. These include the caudate, hippocampus, specialized circumventricular organs, hypothalamus, and the downstream pia-glia and arachnoid membranes. The CSF circulatory system normally provides micronutrients, neurotrophins, hormones, neuropeptides, and growth factors extensively to neuronal networks. Therefore, drugs directed to CSF can modulate a variety of endocrine, immunologic, and behavioral phenomema; and can help to restore brain interstitial and cellular homeostasis disrupted by disease and trauma. This review integrates information from animal models that demonstrates marked physiologic effects of substances introduced into the ventricular system. It also recapitulates how pharmacologic agents administered into the CSF system prevent disease or enhance the brain's ability to recover from chemical and physical insults. In regard to drug distribution in the CNS, the BCSFB interaction with the blood-brain barrier is discussed. With a view toward translational CSF pharmacotherapy, there are several promising innovations in progress: bone marrow cell infusions, CP encapsulation and transplants, neural stem cell augmentation, phage display of peptide ligands for CP epithelium, CSF gene transfer, regulation of leukocyte and cytokine trafficking at the BCSFB, and the purification of neurotoxic CSF in degenerative states. The progressively increasing pharmacological significance of the CP-CSF nexus is analyzed in light of treating AIDS, multiple sclerosis, stroke, hydrocephalus, and Alzheimer's disease.
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Affiliation(s)
- Conrad E Johanson
- Department of Clinical Neurosciences, Rhode Island Hospital, Brown Medical School, Providence, Rhode Island 02912, USA.
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7
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Abstract
Thyroid hormones (THs) play critical roles in the differentiation, growth, metabolism, and physiological function of virtually all tissues. TH binds to receptors that are ligand-regulatable transcription factors belonging to the nuclear hormone receptor superfamily. Tremendous progress has been made recently in our understanding of the molecular mechanisms that underlie TH action. In this review, we present the major advances in our knowledge of the molecular mechanisms of TH action and their implications for TH action in specific tissues, resistance to thyroid hormone syndrome, and genetically engineered mouse models.
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Affiliation(s)
- P M Yen
- Molecular Regulation and Neuroendocrinology Section, Clinical Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
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8
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Kuchler-Bopp S, Dietrich JB, Zaepfel M, Delaunoy JP. Receptor-mediated endocytosis of transthyretin by ependymoma cells. Brain Res 2000; 870:185-94. [PMID: 10869517 DOI: 10.1016/s0006-8993(00)02413-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Transthyretin (TTR) is involved in the transport of thyroxine (T4) and retinol-binding protein (RBP) in cerebrospinal fluid (CSF) and serum. TTR is secreted in the CSF by the epithelial cells of choroid plexus. The binding of [(125)I]TTR to cultured ependymoma cells which form the brain cerebrospinal barrier, was studied to determine whether these cells carry receptor(s) for TTR. TTR was bound by ependymoma cells in a time-dependent manner reaching equilibrium within 2 h. Scatchard analysis was consistent with a single class of high-affinity binding sites with a K(d) of approximately 18 nM. Saturable high-affinity binding of human TTR has previously been described in rat primary hepatocytes and human renal adenocarcinoma, neuroblastoma, hepatoma and astrocytoma cells, and also transformed lung cells. Endocytosis of fluorescent or biotinylated TTR was observed in ependymoma cells in cytoplasmic vesicles but TTR did not colocalize with clathrin in endocytic coated vesicles. Endocytosis of TTR was inhibited by high sucrose concentration (0.45 M). Finally, ligand blotting and chemical-linking experiments revealed the presence of a approximately 100 kDa putative TTR receptor on the ependymoma cell membrane. Receptor binding of TTR provides a potential mechanism for the delivery of T4 within the central nervous system.
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MESH Headings
- Animals
- Biological Transport/physiology
- Blotting, Northern
- Brain Neoplasms
- Cell Line, Transformed/chemistry
- Cell Line, Transformed/metabolism
- Cell Line, Transformed/ultrastructure
- Endocytosis/physiology
- Ependyma/cytology
- Ependymoma
- Gene Expression Regulation, Neoplastic
- Humans
- Iodine Radioisotopes
- Mice
- Mice, Transgenic
- Microscopy, Electron
- Prealbumin/genetics
- Prealbumin/pharmacokinetics
- RNA, Messenger/analysis
- Rats
- Receptors, Albumin/analysis
- Receptors, Albumin/metabolism
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Affiliation(s)
- S Kuchler-Bopp
- Laboratoire de Neurobiologie Moléculaire des Interactions Cellulaires, 11, rue Humann, 67085 cedex, Strasbourg, France.
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9
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Viguié C, Battaglia DF, Krasa HB, Thrun LA, Karsch FJ. Thyroid hormones act primarily within the brain to promote the seasonal inhibition of luteinizing hormone secretion in the ewe. Endocrinology 1999; 140:1111-7. [PMID: 10067833 DOI: 10.1210/endo.140.3.6543] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In the ewe, thyroid hormones are required for the seasonal suppression of GnRH and LH secretion, thereby maintaining an annual rhythm in reproductive activity. The primary site of action of thyroid hormones is unknown; in particular, there is no evidence to distinguish a central from a peripheral action. In this study, we test the hypothesis that thyroid hormones can act directly within the brain to promote GnRH/LH seasonal inhibition. Ovariectomized estradiol-treated ewes were thyroidectomized late in the breeding season to prevent seasonal LH inhibition. T4 was then infused for 3 months, either peripherally or centrally. Neuroendocrine reproductive state was monitored by assaying the LH concentration in biweekly blood samples. Central infusion of low dose T4, which restored a physiological concentration of the hormone in cerebrospinal fluid of these thyroidectomized ewes, promoted the neuroendocrine changes that lead to anestrus. The serum LH concentration in these animals fell at the same time as the seasonal LH decline in euthyroid controls. Neither this same T4 dose infused peripherally nor vehicle infused centrally was effective; LH remained elevated, signifying blockade of the mechanism for anestrus. Our results provide strong evidence that thyroid hormones can act directly within the brain to promote seasonal inhibition of neuroendocrine reproductive function in the ewe.
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Affiliation(s)
- C Viguié
- Reproductive Sciences Program, University of Michigan, Ann Arbor 48109-0404, USA
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10
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Lie-Venema H, Hakvoort TB, van Hemert FJ, Moorman AF, Lamers WH. Regulation of the spatiotemporal pattern of expression of the glutamine synthetase gene. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1998; 61:243-308. [PMID: 9752723 DOI: 10.1016/s0079-6603(08)60829-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Glutamine synthetase, the enzyme that catalyzes the ATP-dependent conversion of glutamate and ammonia into glutamine, is expressed in a tissue-specific and developmentally controlled manner. The first part of this review focuses on its spatiotemporal pattern of expression, the factors that regulate its levels under (patho)physiological conditions, and its role in glutamine, glutamate, and ammonia metabolism in mammals. Glutamine synthetase protein stability is more than 10-fold reduced by its product glutamine and by covalent modifications. During late fetal development, translational efficiency increases more than 10-fold. Glutamine synthetase mRNA stability is negatively affected by cAMP, whereas glucocorticoids, growth hormone, insulin (all positive), and cAMP (negative) regulate its rate of transcription. The signal transduction pathways by which these factors may regulate the expression of glutamine synthetase are briefly discussed. The second part of the review focuses on the evolution, structure, and transcriptional regulation of the glutamine synthetase gene in rat and chicken. Two enhancers (at -6.5 and -2.5 kb) were identified in the upstream region and two enhancers (between +156 and +857 bp) in the first intron of the rat glutamine synthetase gene. In addition, sequence analysis suggests a regulatory role for regions in the 3' untranslated region of the gene. The immediate-upstream region of the chicken glutamine synthetase gene is responsible for its cell-specific expression, whereas the glucocorticoid-induced developmental appearance in the neural retina is governed by its far-upstream region.
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Affiliation(s)
- H Lie-Venema
- Department of Anatomy and Embryology, University of Amsterdam, The Netherlands
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11
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Kuchler-Bopp S, Ittel ME, Dietrich JB, Reeber A, Zaepfel M, Delaunoy JP. The presence of transthyretin in rat ependymal cells is due to endocytosis and not synthesis. Brain Res 1998; 793:219-30. [PMID: 9630636 DOI: 10.1016/s0006-8993(98)00154-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The presence and synthesis of transthyretin, a major carrier protein of thyroxine in rat cerebrospinal fluid, was investigated in choroid plexus epithelial cells and ependymal cells by immunocytochemistry, in situ hybridization, and analysis by Northern and Western blot using a specific oligonucleotide probe and a specific polyclonal antibody to transthyretin. Choroid plexus epithelial cells expressed transthyretin at high levels in developing rat cerebral hemispheres and in cultured cells. These cells secreted transthyretin into the cerebrospinal fluid. In the developing rat brain transthyretin was present in the cytoplasm of ependymal cells, in vesicles in contact with the apical membrane and in cilia. In ependymal cell cultures this protein was particularly abundant in the cilia of these cells. In contrast, ependymal cells did not synthesize transthyretin. It is postulated that transthyretin is transported to ependymal cells from the cerebrospinal fluid by endocytosis.
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Affiliation(s)
- S Kuchler-Bopp
- Laboratoire de Neurobiologie Moléculaire des Interactions Cellulaires, UPR 416 CNRS, Strasbourg, France
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12
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Gabrion JB, Herbuté S, Bouillé C, Maurel D, Kuchler-Bopp S, Laabich A, Delaunoy JP. Ependymal and choroidal cells in culture: characterization and functional differentiation. Microsc Res Tech 1998; 41:124-57. [PMID: 9579599 DOI: 10.1002/(sici)1097-0029(19980415)41:2<124::aid-jemt3>3.0.co;2-u] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
During the past 10 years, our teams developed long-term primary cultures of ependymal cells derived from ventricular walls of telencephalon and hypothalamus or choroidal cells (modified ependymal cells) derived from plexuses dissected out of fetal or newborn mouse or rat brains. Cultures were established in serum-supplemented or chemically defined media after seeding on serum-, fibronectin-, or collagen-laminin-coated plastic dishes or semipermeable inserts. To identify and characterize cell types growing in our cultures, we used morphological features provided by phase contrast, scanning, and transmission electron microscopy. We used antibodies against intermediate filament proteins (vimentin, glial fibrillary acidic protein, cytokeratin, desmin, neurofilament proteins), actin, myosin, ciliary rootlets, laminin, and fibronectin in single or double immunostaining, and monoclonal antibodies against epitopes of ependymal or endothelial cells, to recognize ventricular wall cell types with immunological criteria. Ciliated or nonciliated ependymal cells in telencephalic cultures, tanycytes and ciliated and nonciliated ependymal cells in hypothalamic cultures always exceeded 75% of the cultured cells under the conditions used. These cells were characterized by their cell shape and epithelial organization, by their apical differentiations observed by scanning and transmission electron microscopy, and by specific markers (e.g., glial fibrillary acidic protein, ciliary rootlet proteins, DARPP 32) detected by immunofluorescence. All these cultured ependymal cell types remarkably resembled in vivo ependymocytes in terms of molecular markers and ultrastructural features. Choroidal cells were also maintained for several weeks in culture, and abundantly expressed markers were detected in both choroidal tissue and culture (Na+-K+-dependent ATPase, DARPP 32, G proteins, ANP receptors). In this review, the culture models we developed (defined in terms of biological material, media, substrates, duration, and subculturing) are also compared with those developed by other investigators during the last 10 years. Focusing on morphological and functional approaches, we have shown that these culture models were suitable to investigate and provide new insights on (1) the gap junctional communication of ependymal, choroidal, and astroglial cells in long-term primary cultures by freeze-fracture or dye transfer of Lucifer Yellow CH after intracellular microinjection; (2) some ionic channels; (3) the hormone receptors to tri-iodothyronine or atrial natriuretic peptides; (4) the regulatory effect of tri-iodothyronine on glutamine synthetase expression; (5) the endocytosis and transcytosis of proteins; and (6) the morphogenetic effects of galactosyl-ceramide. We also discuss new insights provided by recent results reported on in vitro ependymal and choroidal expressions of neuropeptide-processing enzymes and neurosecretory proteins or choroidal expression of transferrin regulated through serotoninergic activation.
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Affiliation(s)
- J B Gabrion
- UMR CNRS 5539, Université Montpellier 2, France.
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13
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Abstract
The cilated ependymocytes that line the ventricles are decorated by a network of serotoninergic supra-ependymal axons, which are thought to regulate their function. The neurones of origin contain both serotonin and phosphate-activated glutaminase, which raises the possibility that the supra-ependymal axons are also glutamatergic. Using immunocytochemistry, the present study has demonstrated the presence of glutamate in many supra-ependymal axons, as well as in the cilia of ependymocytes. We suggest that glutamate in supra-ependymal axons, counterbalances or opposes the action elicited by serotonin. Glutamate taken up by ependymocytes may supplement metabolic pathways in these cells and could be used to fuel the high energy demands of their cilia.
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Affiliation(s)
- S R Robinson
- Vision, Touch & Hearing Research Centre, University of Queensland, St. Lucia, Australia
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14
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Abstract
This review summarizes the current scientific literature concerning the ependymal lining of the cerebral ventricles of the brain with an emphasis on selective barrier function and protective roles for the common ependymal cell. Topics covered include the development, morphology, protein and enzyme expression including reactive changes, and pathology. Some cells lining the neural tube are committed at an early stage to becoming ependymal cells. They serve a secretory function and perhaps act as a cellular/axonal guidance system, particularly during fetal development. In the mature mammalian brain ependymal cells possess the structural and enzymatic characteristics necessary for scavenging and detoxifying a wide variety of substances in the CSF, thus forming a metabolic barrier at the brain-CSF interface.
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Affiliation(s)
- M R Del Bigio
- Department of Pathology, Health Sciences Centre, Winnipeg, Canada
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15
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Lezoualc'h F, Hassan A, Abdel-Tawab H, Puymirat J, Demeneix BA. Precocious auto-induction of thyroid hormone receptors in embryonic chick hypothalamic neurons. Neurosci Lett 1994; 180:197-202. [PMID: 7700579 DOI: 10.1016/0304-3940(94)90520-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Qualitative immunocytochemical and quantitative autoradiographic approaches were used to examine the presence of thyroid hormone receptor (TR) proteins in embryonic chick hypothalamic cultures and the effect of T3 on their expression. We used antibodies raised against rat TRs having first verified that they recognised nuclear T3 binding proteins in extracts from chick brains. TRs were expressed in embryonic hypothalamic neurons from 6 day-old chick embryos maintained 4 days in vitro, and their expression was up-regulated by T3. This demonstration of TRs in embryonic hypothalamic neurons suggests that a physiological mechanism for early regulation of the hypothalamic neuropeptide, thyrotropin releasing hormone, is installed prior to the onset of thyroid function.
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Affiliation(s)
- F Lezoualc'h
- Laboratoire de Physiologie Générale et Comparée, URA 90 CNRS, Muséum National d'Histoire Naturelle, Paris, France
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