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Corrêa-Velloso JC, Linardi AM, Glaser T, Velloso FJ, Rivas MP, Leite REP, Grinberg LT, Ulrich H, Akins MR, Chiavegatto S, Haddad LA. Fmr1 exon 14 skipping in late embryonic development of the rat forebrain. BMC Neurosci 2022; 23:32. [PMID: 35641906 PMCID: PMC9158170 DOI: 10.1186/s12868-022-00711-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 04/24/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Fragile X syndrome, the major cause of inherited intellectual disability among men, is due to deficiency of the synaptic functional regulator FMR1 protein (FMRP), encoded by the FMRP translational regulator 1 (FMR1) gene. FMR1 alternative splicing produces distinct transcripts that may consequently impact FMRP functional roles. In transcripts without exon 14 the translational reading frame is shifted. For deepening current knowledge of the differential expression of Fmr1 exon 14 along the rat nervous system development, we conducted a descriptive study employing quantitative RT-PCR and BLAST of RNA-Seq datasets. RESULTS We observed in the rat forebrain progressive decline of total Fmr1 mRNA from E11 to P112 albeit an elevation on P3; and exon-14 skipping in E17-E20 with downregulation of the resulting mRNA. We tested if the reduced detection of messages without exon 14 could be explained by nonsense-mediated mRNA decay (NMD) vulnerability, but knocking down UPF1, a major component of this pathway, did not increase their quantities. Conversely, it significantly decreased FMR1 mRNA having exon 13 joined with either exon 14 or exon 15 site A. CONCLUSIONS The forebrain in the third embryonic week of the rat development is a period with significant skipping of Fmr1 exon 14. This alternative splicing event chronologically precedes a reduction of total Fmr1 mRNA, suggesting that it may be part of combinatorial mechanisms downregulating the gene's expression in the late embryonic period. The decay of FMR1 mRNA without exon 14 should be mediated by a pathway different from NMD. Finally, we provide evidence of FMR1 mRNA stabilization by UPF1, likely depending on FMRP.
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Affiliation(s)
- Juliana C Corrêa-Velloso
- Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277 # 327, São Paulo, SP, 05508-090, Brazil
| | - Alessandra M Linardi
- Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277 # 327, São Paulo, SP, 05508-090, Brazil
| | - Talita Glaser
- Department of Biochemistry, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Fernando J Velloso
- Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277 # 327, São Paulo, SP, 05508-090, Brazil
| | - Maria P Rivas
- Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277 # 327, São Paulo, SP, 05508-090, Brazil
| | - Renata E P Leite
- Department of Pathology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Lea T Grinberg
- Department of Pathology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Henning Ulrich
- Department of Biochemistry, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Michael R Akins
- Department of Biology, Drexel University, Philadelphia, PA, USA
| | - Silvana Chiavegatto
- Department of Pharmacology, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.,Department of Psychiatry, Instituto de Psiquiatria, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Luciana A Haddad
- Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277 # 327, São Paulo, SP, 05508-090, Brazil.
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Janzen D, Bakirci E, Wieland A, Martin C, Dalton PD, Villmann C. Cortical Neurons form a Functional Neuronal Network in a 3D Printed Reinforced Matrix. Adv Healthc Mater 2020; 9:e1901630. [PMID: 32181992 DOI: 10.1002/adhm.201901630] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/17/2020] [Accepted: 03/04/2020] [Indexed: 12/15/2022]
Abstract
Impairments in neuronal circuits underly multiple neurodevelopmental and neurodegenerative disorders. 3D cell culture models enhance the complexity of in vitro systems and provide a microenvironment closer to the native situation than with 2D cultures. Such novel model systems will allow the assessment of neuronal network formation and their dysfunction under disease conditions. Here, mouse cortical neurons are cultured from embryonic day E17 within in a fiber-reinforced matrix. A soft Matrigel with a shear modulus of 31 ± 5.6 Pa is reinforced with scaffolds created by melt electrowriting, improving its mechanical properties and facilitating the handling. Cortical neurons display enhance cell viability and the neuronal network maturation in 3D, estimated by staining of dendrites and synapses over 21 days in vitro, is faster in 3D compared to 2D cultures. Using functional readouts with electrophysiological recordings, different firing patterns of action potentials are observed, which are absent in the presence of the sodium channel blocker, tetrodotoxin. Voltage-gated sodium currents display a current-voltage relationship with a maximum peak current at -25 mV. With its high customizability in terms of scaffold reinforcement and soft matrix formulation, this approach represents a new tool to study neuronal networks in 3D under normal and, potentially, disease conditions.
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Affiliation(s)
- Dieter Janzen
- Institute for Clinical NeurobiologyUniversity Hospital Würzburg Versbacherstr. 5 Würzburg 97078 Germany
| | - Ezgi Bakirci
- Department of Functional Materials in Medicine and Dentistry and Bavarian Polymer InstituteUniversity Hospital Würzburg Pleicherwall 2 Würzburg 97070 Germany
| | - Annalena Wieland
- Department of Obstetrics and GynecologyUniversity Hospital ErlangenLaboratory for Molecular MedicineFAU Erlangen‐Nürnberg Universitätsstrasse, 21–23 Erlangen 91054 Germany
| | - Corinna Martin
- Institute for Clinical NeurobiologyUniversity Hospital Würzburg Versbacherstr. 5 Würzburg 97078 Germany
| | - Paul D. Dalton
- Department of Functional Materials in Medicine and Dentistry and Bavarian Polymer InstituteUniversity Hospital Würzburg Pleicherwall 2 Würzburg 97070 Germany
| | - Carmen Villmann
- Institute for Clinical NeurobiologyUniversity Hospital Würzburg Versbacherstr. 5 Würzburg 97078 Germany
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3
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Cell death and proliferation in acute slices and organotypic cultures of mammalian CNS. Prog Neurobiol 2009; 88:221-45. [DOI: 10.1016/j.pneurobio.2009.01.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Revised: 12/09/2008] [Accepted: 01/07/2009] [Indexed: 11/24/2022]
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Viberg H. Neonatal ontogeny and neurotoxic effect of decabrominated diphenyl ether (PBDE 209) on levels of synaptophysin and tau. Int J Dev Neurosci 2009; 27:423-9. [DOI: 10.1016/j.ijdevneu.2009.05.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Revised: 04/28/2009] [Accepted: 05/13/2009] [Indexed: 10/20/2022] Open
Affiliation(s)
- Henrik Viberg
- Department of Environmental ToxicologyUppsala UniversityNorbyvägen 18AS‐752 36UppsalaSweden
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5
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Laffont-Proust I, Fonta C, Renaud L, Hässig R, Moya KL. Developmental changes in cellular prion protein in primate visual cortex. J Comp Neurol 2008; 504:646-58. [PMID: 17722030 DOI: 10.1002/cne.21475] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cellular prion protein (PrP(c)) is a cell surface glycoprotein highly expressed in neurons, and a protease-resistant conformer of the protein accumulates in the brain parenchyma in prion diseases. In human prion diseases, visual cortex and visual function can be affected. We examined both the levels and the localization of PrP(c) in developing visual cortex of the common marmoset. Western blot analysis showed that PrP(c) increased from the day of birth through adulthood, and this increase correlated with the progression of synapse formation. Immunohistochemistry showed that PrP(c) was present in fiber tracts of the neonate, and this immunoreactivity was lost with maturation. Within the neuropil, the laminar distribution of PrP(c) changed with age. In the neonate, PrP(c) immunoreactivity was strongest in layer 1, where the earliest synapses form. At the end of the first postnatal week, layer 4C, as identified by its strong cytochrome oxidase activity, was noticeably lighter in terms of PrP(c) immunoreactivity than the adjacent layers. The contrast between the strong immunoreactivity in both supragranular and infragranular layers and weak immunoreactivity in layer 4C increased with age. Layers 2/3 and 5 contained more intense PrP(c) immunoreactivity; these layers receive thalamic input from the koniocellular division of the LGN, and these layers of the LGN also had strong PrP(c) immunoreactivity. Together, these results provide evidence for PrP(c) localization in an identified functional pathway and may shed some light on prion disease pathogenesis.
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Affiliation(s)
- Isabelle Laffont-Proust
- Institut National de la Santé et de la Recherche Médicale Avenir Team--Human Prion Diseases, IFR70, Neuropathology, Salpêtrière Hospital, Paris 75013, France
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6
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Viberg H, Mundy W, Eriksson P. Neonatal exposure to decabrominated diphenyl ether (PBDE 209) results in changes in BDNF, CaMKII and GAP-43, biochemical substrates of neuronal survival, growth, and synaptogenesis. Neurotoxicology 2007; 29:152-9. [PMID: 18061678 DOI: 10.1016/j.neuro.2007.10.007] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Revised: 10/09/2007] [Accepted: 10/13/2007] [Indexed: 12/01/2022]
Abstract
Mammals have a marked period of rapid brain growth and development (BGS), which is postnatal in mice and rats, spanning the first 3-4 weeks of life and reaching its peak around postnatal day 10. CaMKII, GAP-43 and BDNF play important roles during the BGS in mammals. One class of flame retardants, polybrominated diphenyl ethers (PBDEs), are present and increasing in the environment and in human milk, which is also true for the only congener still in use, decabrominated diphenyl ether (PBDE 209). In the present study, the brains from 1, 3, 7, 10, 14 and 28 days old mice, were analysed for CaMKII and GAP-43. The level of CaMKII increases continuously during the neonatal period, while GAP-43 has a bell-shaped ontogeny curve, which peaks around postnatal day 10, in mouse brain. Furthermore, the effects of PBDE 209 on the developmental expression of CaMKII, GAP-43 and BDNF were examined in mice. Neonatal NMRI-male mice were orally exposed on days 3-20.1mgPBDE 209/kg body weight. The animals were euthanized 7 days after exposure to PBDE 209 and levels of CaMKII, GAP-43 and BDNF were analysed in different brain regions. The protein analysis showed that CaMKII increased significantly in hippocampus, but not in cortex, in animals 7 days after exposure to PBDE 209. GAP-43 showed a significant increase in hippocampus and a significant decrease in cortex of animals 7 days after exposure to PBDE 209. BDNF decreased significantly in hippocampus, but not in cortex, in mice 7 days after exposure to PBDE 209. This shows that PBDE 209 affects important proteins involved in normal maturation of the brain and further strengthen our findings concerning PBDE 209 as a developmental neurotoxicological agent.
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Affiliation(s)
- Henrik Viberg
- Department of Environmental Toxicology, Uppsala University, Norbyvägen 18A, S-75236 Uppsala, Sweden.
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7
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Buckby LE, Mummery R, Crompton MR, Beesley PW, Empson RM. Comparison of neuroplastin and synaptic marker protein expression in acute and cultured organotypic hippocampal slices from rat. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2004; 150:1-7. [PMID: 15126032 DOI: 10.1016/j.devbrainres.2004.01.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/26/2004] [Indexed: 11/23/2022]
Abstract
Organotypic hippocampal slice cultures can be used to study hippocampal biochemistry and physiology over a chronic period on the days to weeks timescale. In order to validate the organotypic hippocampal slice culture for our ongoing studies of synaptic function, we have compared, using Western blotting, the levels of a number of synaptic proteins from in vitro organotypic hippocampal slice cultures with those from in vivo hippocampal slices prepared from age-matched controls. We chose to follow the developmental expression of the neuroplastin (np) family of immunoglobulin related cell adhesion molecules (CAMs), np65, a brain specific isoform highly expressed in hippocampal neurones and np55 a more widely expressed isoform and two synaptic marker proteins, synaptophysin, a pre-synaptic marker and post-synaptic density protein-95, PSD95, a post-synaptic marker. All showed increasing expression over the developmental time period, both in vivo and in vitro. The level of both neuroplastins was also consistent between the in vivo and in vitro preparations, whereas the level of PSD95 was markedly increased in the organotypic hippocampal slice cultures while the level of synaptophysin was slightly decreased. Whilst these findings may indicate some differences in the composition and organisation of synapses, the developmental expression profiles of these synaptic proteins within organotypic hippocampal slice cultures suggests they are a valid model for the study of synapse function and development in vitro.
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Affiliation(s)
- Lucy E Buckby
- School of Biological Sciences, Royal Holloway University of London, Egham Hill, Egham, Surrey, TW20 0EX, UK
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Wirth MJ, Brun A, Grabert J, Patz S, Wahle P. Accelerated dendritic development of rat cortical pyramidal cells and interneurons after biolistic transfection with BDNF and NT4/5. Development 2004; 130:5827-38. [PMID: 14573511 DOI: 10.1242/dev.00826] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Neurotrophins are candidate molecules for regulating dendritogenesis. We report here on dendritic growth of rat visual cortex pyramidal and interneurons overexpressing 'brain-derived neurotrophic factor' BDNF and 'neurotrophin 4/5' NT4/5. Neurons in organotypic cultures were transfected with plasmids encoding either 'enhanced green fluorescent protein' EGFP, BDNF/EGFP or NT4/5/EGFP either at the day of birth with analysis at 5 days in vitro, or at 5 days in vitro with analysis at 10 days in vitro. In pyramidal neurons, both TrkB ligands increased dendritic length and number of segments without affecting maximum branch order and number of primary dendrites. In the early time window, only infragranular neurons were responsive. Neurons in layers II/III became responsive to NT4/5, but not BDNF, during the later time window. BDNF and NT4/5 transfectants at 10 days in vitro had still significantly shorter dendrites than adult pyramidal neurons, suggesting a massive growth spurt after 10 days in vitro. However, segment numbers were already in the range of adult neurons. Although this suggested a role for BDNF, long-term activity-deprived, and thus BDNF-deprived, pyramidal cells developed a dendritic complexity not different from neurons in active cultures except for higher spine densities on neurons of layers II/III and VI. Neutralization of endogenous NT4/5 causes shorter and less branched dendrites at 10 days in vitro suggesting an essential role for NT4/5. Neutralization of BDNF had no effect. Transfected multipolar interneurons became identifiable during the second time window. Both TrkB ligands significantly increased number of segments and branch order towards the adult state with little effects on dendritic length. The results suggested that early in development BDNF and NT4/5 probably accelerate dendritogenesis in an autocrine fashion. In particular, branch formation was advanced towards the adult pattern in pyramidal cells and interneurons.
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Affiliation(s)
- Marcus J Wirth
- AG Entwicklungsneurobiologie, Fakultät für Biologie, Ruhr-Universität, ND 6/56a, D-44780 Bochum, Germany.
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9
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Corner MA, van Pelt J, Wolters PS, Baker RE, Nuytinck RH. Physiological effects of sustained blockade of excitatory synaptic transmission on spontaneously active developing neuronal networks--an inquiry into the reciprocal linkage between intrinsic biorhythms and neuroplasticity in early ontogeny. Neurosci Biobehav Rev 2002; 26:127-85. [PMID: 11856557 DOI: 10.1016/s0149-7634(01)00062-8] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Spontaneous bioelectric activity (SBA) taking the form of extracellularly recorded spike trains (SBA) has been quantitatively analyzed in organotypic neonatal rat visual cortex explants at different ages in vitro, and the effects investigated of both short- and long-term pharmacological suppression of glutamatergic synaptic transmission. In the presence of APV, a selective NMDA receptor blocker, 1-2- (but not 3-)week-old cultures recovered their previous SBA levels in a matter of hours, although in imitation of the acute effect of the GABAergic inhibitor picrotoxin (PTX), bursts of action potentials were abnormally short and intense. Cultures treated either overnight or chronically for 1-3 weeks with APV, the AMPA/kainate receptor blocker DNQX, or a combination of the two were found to display very different abnormalities in their firing patterns. NMDA receptor blockade for 3 weeks produced the most severe deviations from control SBA, consisting of greatly prolonged and intensified burst firing with a strong tendency to be broken up into trains of shorter spike clusters. This pattern was most closely approximated by acute GABAergic disinhibition in cultures of the same age, but this latter treatment also differed in several respects from the chronic-APV effect. In 2-week-old explants, in contrast, it was the APV+DNQX treated group which showed the most exaggerated spike bursts. Functional maturation of neocortical networks, therefore, may specifically require NMDA receptor activation (not merely a high level of neuronal firing) which initially is driven by endogenous rather than afferent evoked bioelectric activity. Putative cellular mechanisms are discussed in the context of a thorough review of the extensive but scattered literature relating activity-dependent brain development to spontaneous neuronal firing patterns.
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Affiliation(s)
- M A Corner
- Academic Medical Centre, Meibergdreef 33, Netherlands Institute for Brain Research, 1105 AZ Amsterdam, The Netherlands.
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10
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Bender R, Hoffmann MC, Frotscher M, Nitsch C. Species-specific expression of parvalbumin in the entorhinal cortex of the Mongolian gerbil: dependence on local activity but not extrinsic afferents. Neuroscience 2001; 99:423-31. [PMID: 11029535 DOI: 10.1016/s0306-4522(00)00208-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mongolian gerbils are genetically predisposed to develop epileptic seizures in limbic structures. A species-specific property of the Mongolian gerbil is the expression of the calcium-binding protein parvalbumin in the perforant path where it is predominantly concentrated in nerve terminals. To test the hypothesis that this atypical expression of parvalbumin is induced by seizure-correlated hyperactivity in the entorhinohippocampal loop, we investigated whether it is dependent on extrinsic afferents to the entorhinal cortex. We cultivated organotypic slice cultures of neonate gerbil entorhinal cortex, isolated from all regions it is normally connected with in vivo. In these cultures, parvalbumin-expressing neurons demonstrated their characteristic features like in vivo. Blockade of spontaneous local activity with the sodium-channel blocker tetrodotoxin, however, considerably reduced the number of parvalbumin-expressing neurons in culture. These results indicate that spontaneous local activity, but not activity mediated by extrinsic afferents, is an essential factor for the expression of parvalbumin in the entorhinal cortex of the Mongolian gerbil.
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Affiliation(s)
- R Bender
- Institute of Anatomy I, University of Freiburg, Albertstr. 17, D-79104, Freiburg, Germany
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11
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Bixel MG, Hamprecht B. Immunocytochemical localization of beta-methylcrotonyl-CoA carboxylase in astroglial cells and neurons in culture. J Neurochem 2000; 74:1059-67. [PMID: 10693937 DOI: 10.1046/j.1471-4159.2000.0741059.x] [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: 11/20/2022]
Abstract
Astroglia-rich primary cultures and brain slices rapidly metabolize branched-chain amino acids (BCAAs), in particular leucine, as energy substrates. To allocate the capacity to degrade leucine oxidatively in neural cells, we have purified beta-methylcrotonyl-CoA carboxylase (beta-MCC) from rat liver as one of the enzymes unique for the irreversible catabolic pathway of leucine. Polyclonal antibodies raised against beta-MCC specifically cross-reacted with both enzyme subunits in liver and brain homogenates. Immunocytochemical examination of astroglia-rich rat primary cultures demonstrated the presence of beta-MCC in astroglial cells, where the enzyme was found to be located in the mitochondria, the same organelle that the mitochondrial isoform of the BCA(A) aminotransferase (BCAT) is located in. This colocalization of the two enzymes supports the hypothesis that mitochondrial BCAT is the isoenzyme that in brain energy metabolism prepares the carbon skeleton of leucine for irreversible degradation in astrocytes. Analysis of neuron-rich primary cultures revealed also that the majority of neurons contained beta-MCC. The presence of beta-MCC in most neurons demonstrates their ability to degrade the alpha-ketoisocaproate that could be provided by neighboring astrocytes or could be generated locally from leucine by the action of the cytosolic isoform of BCAT that is known to occur in neurons.
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Affiliation(s)
- M G Bixel
- Physiologisch-chemisches Institut der Universität Tübingen, Germany
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12
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Wirth MJ, Gorba T, Wahle P. Epigenetic factors regulate the NPY expression in rat cortical neurons. REGULATORY PEPTIDES 1998; 75-76:283-92. [PMID: 9802421 DOI: 10.1016/s0167-0115(98)00080-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The NPY phenotype expressed in a subset of rat neocortical neurons is influenced by a variety of epigenetic factors. In the present study, we analyzed the role of synaptically driven spontaneous bioelectric (action potential) activity (SBA) and neurotrophic factors. Our model systems are organotypic monocultures of visual cortex which either grow as spontaneously active cultures or as activity-blocked cultures to which neurotrophic factors can be applied via the medium. NPY mRNA expressing neurons are detected by in situ hybridization and are quantified as a percentage of all neurons. In spontaneously active cultures, about 7% of all neurons express NPY mRNA. This expression is regulated by SBA, because expression is reduced to about 2% by different activity blockade paradigms. When putative NPY neurons differentiate under activity blockade, they are unable to restitute the NPY expression during a subsequent period of SBA. A restitution of the NPY phenotype in 6-7% of the neurons after a transient blockade of activity is only possible when neurons were initially allowed to differentiate in the presence of SBA. We then analyzed whether neurotrophic factors known to promote NPY expression can do so in the absence of SBA. Neurotrophin-4/5 and leukemia inhibitory factor, but not brain-derived neurotrophic factor and neurotrophin-3, stimulate the NPY phenotype in the absence of SBA. In situ hybridization in combination with immuno-fluorescence reveals that NPY-ir neurons express the receptors trkB or LIFRbeta, but not trkC. This coexpression pattern explains why neurotrophin-4/5 and leukemia inhibitory factor are efficient regulators of the NPY-expression. Our results suggest that the NPY expression in neocortical neurons depends on epigenetic factors: spontaneous activity and neurotrophic factors modulate the expression and are thus involved in shaping the neurochemical architecture of the cerebral cortex.
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Affiliation(s)
- M J Wirth
- AG Entwicklungsneurobiologie, Fakultät für Biologie, Ruhr-Universität, Bochum, Germany
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13
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Sieg F, Obst K, Gorba T, Riederer B, Pape HC, Wahle P. Postnatal expression pattern of calcium-binding proteins in organotypic thalamic cultures and in the dorsal thalamus in vivo. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1998; 110:83-95. [PMID: 9733927 DOI: 10.1016/s0165-3806(98)00097-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The present study describes the postnatal expression of calbindin, calretinin and parvalbumin and glutamic acid decarboxylase (GAD) and microtubule-associated protein 2 (MAP2) in organotypic monocultures of rat dorsal thalamus compared to the thalamus in vivo. Cultures were maintained for up to 7 weeks. Cortex-conditioned medium improved the survival of thalamic cultures. MAP2-immunoreactive material was present in somata and dendrites of small and large-sized neurons throughout the cultures. Parvalbumin immunoreactivity was present in larger multipolar or bitufted neurons along the edge of a culture. These neurons also displayed strong parvalbumin mRNA and GAD mRNA expression, and GABA immunoreactivity. They likely corresponded to cells of the nucleus reticularis thalami. Parvalbumin mRNA, but neither parvalbumin protein nor GAD mRNA, was expressed in neurons with large somata within the explant. They likely represented relay cells. GAD mRNA, but not parvalbumin mRNA, was expressed in small neurons within the explants. Small neurons also displayed calbindin- and calretinin-immunoreactivity. The small neurons likely represented local circuit neurons. The time course of expression of the calcium-binding proteins revealed that all were present at birth with the predicted molecular weights. A low, but constant parvalbumin expression was observed in vitro without the developmental increase seen in vivo, which most likely represented parvalbumin from afferent sources. In contrast, the explantation transiently downregulated the calretinin and calbindin expression, but the neurons recovered the expression after 14 and 21 days, respectively. In conclusion, thalamic monocultures older than three weeks represent a stable neuronal network containing well differentiated neurons of the nucleus reticularis thalami, relay cells and local circuit neurons.
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Affiliation(s)
- F Sieg
- Entwicklungsbiologie, Fakultät für Biologie, ND 7/31, Ruhr-Universität, D-44780, Bochum, Germany
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Wirth MJ, Obst K, Wahle P. NT-4/5 and LIF, but not NT-3 and BDNF, promote NPY mRNA expression in cortical neurons in the absence of spontaneous bioelectrical activity. Eur J Neurosci 1998; 10:1457-64. [PMID: 9749800 DOI: 10.1046/j.1460-9568.1998.00157.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Epigenetic factors are known to influence the differentiation of neocortical neurons. The present study analyses the role of spontaneous bioelectrical activity (SBA) and neurotrophic factors on the expression of neuropeptide Y (NPY) in rat visual cortical neurons using organotypic monocultures prepared from newborn animals and in situ hybridization to detect the NPY messenger ribonucleic acid (mRNA). Spontaneously active cortex cultures display NPY mRNA expression in about 7% of all cortical neurons from 10 days in vitro (DIV) on. Blocking the SBA by chronic application of 10 mM Mg2+ for 3-30 DIV reduces the percentage of NPY neurons to about 2%. Allowing an initial phase of SBA (1-20 DIV) followed by an SBA blockade (for 21-50 DIV) results in 2% labelled neurons, indicating a dramatic reduction of NPY mRNA expression in the absence of SBA. Surprisingly, the reverse experiment (a period of SBA blockade for 1-20 DIV followed by a period of SBA recovery for 21-40 DIV) does not cause an upregulation of NPY mRNA expression. However, allowing cultures to differentiate as spontaneously active cultures, then applying a transient period of SBA blockade which is followed by a second period of SBA, does rescue the NPY mRNA expression in 7% of the cortical neurons. We conclude that SBA is a main trigger for NPY mRNA expression and it is particularly important during an early postnatal period of differentiation. We then analysed whether neurotrophic factors known to modulate cortical neuropeptide expression are able to do so in the absence of SBA. Supplementing chronically blocked cultures with the neurotrophins, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), neurotrophin-4/5 (NT-4/5) and the cytokine, leukaemia inhibitory factor (LIF), reveals that BDNF and NT-3 are unable to increase the percentage of NPY neurons. In contrast, LIF and NT-4/5 increase the percentage of NPY neurons to 4 and 6-7%, respectively. Moreover, neurons treated with NT-4/5 display a very high level of NPY mRNA expression in somata and in the dendritic trees. The data suggest a complex interplay and a hierarchy of epigenetic factors in regulating the neurochemical architecture of the developing neocortex.
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Affiliation(s)
- M J Wirth
- AG Entwicklungsneurobiologie, Fakultät für Biologie, Ruhr-Universität, Bochum, Germany
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