1
|
Poshtkohi A, Wade J, McDaid L, Liu J, Dallas ML, Bithell A. Mathematical Modeling of PI3K/Akt Pathway in Microglia. Neural Comput 2024; 36:645-676. [PMID: 38457763 DOI: 10.1162/neco_a_01643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/20/2023] [Indexed: 03/10/2024]
Abstract
The motility of microglia involves intracellular signaling pathways that are predominantly controlled by changes in cytosolic Ca2+ and activation of PI3K/Akt (phosphoinositide-3-kinase/protein kinase B). In this letter, we develop a novel biophysical model for cytosolic Ca2+ activation of the PI3K/Akt pathway in microglia where Ca2+ influx is mediated by both P2Y purinergic receptors (P2YR) and P2X purinergic receptors (P2XR). The model parameters are estimated by employing optimization techniques to fit the model to phosphorylated Akt (pAkt) experimental modeling/in vitro data. The integrated model supports the hypothesis that Ca2+ influx via P2YR and P2XR can explain the experimentally reported biphasic transient responses in measuring pAkt levels. Our predictions reveal new quantitative insights into P2Rs on how they regulate Ca2+ and Akt in terms of physiological interactions and transient responses. It is shown that the upregulation of P2X receptors through a repetitive application of agonist results in a continual increase in the baseline [Ca2+], which causes the biphasic response to become a monophasic response which prolongs elevated levels of pAkt.
Collapse
Affiliation(s)
- Alireza Poshtkohi
- School of Physics, Engineering and Computer Science, University of Hertfordshire, Hatfield, Hertfordshire, U.K.
| | - John Wade
- School of Computing, Engineering and Intelligent Systems, University of Ulster, Londonderry, U.K.
| | - Liam McDaid
- School of Computing, Engineering and Intelligent Systems, University of Ulster, Londonderry, U.K.
| | - Junxiu Liu
- School of Computing, Engineering and Intelligent Systems, University of Ulster, Londonderry, U.K.
| | - Mark L Dallas
- School of Pharmacy, University of Reading, Reading, U.K.
| | - Angela Bithell
- School of Pharmacy, University of Reading, Reading, U.K.
| |
Collapse
|
2
|
Poshtkohi A, Wade J, McDaid L, Liu J, Dallas M, Bithell A. Mathematical modelling of human P2X-mediated plasma membrane electrophysiology and calcium dynamics in microglia. PLoS Comput Biol 2021; 17:e1009520. [PMID: 34723961 PMCID: PMC8584768 DOI: 10.1371/journal.pcbi.1009520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 11/11/2021] [Accepted: 10/02/2021] [Indexed: 01/14/2023] Open
Abstract
Regulation of cytosolic calcium (Ca2+) dynamics is fundamental to microglial function. Temporal and spatial Ca2+ fluxes are induced from a complicated signal transduction pathway linked to brain ionic homeostasis. In this paper, we develop a novel biophysical model of Ca2+ and sodium (Na+) dynamics in human microglia and evaluate the contribution of purinergic receptors (P2XRs) to both intracellular Ca2+ and Na+ levels in response to agonist/ATP binding. This is the first comprehensive model that integrates P2XRs to predict intricate Ca2+ and Na+ transient responses in microglia. Specifically, a novel compact biophysical model is proposed for the capture of whole-cell patch-clamp currents associated with P2X4 and P2X7 receptors, which is composed of only four state variables. The entire model shows that intricate intracellular ion dynamics arise from the coupled interaction between P2X4 and P2X7 receptors, the Na+/Ca2+ exchanger (NCX), Ca2+ extrusion by the plasma membrane Ca2+ ATPase (PMCA), and Ca2+ and Na+ leak channels. Both P2XRs are modelled as two separate adenosine triphosphate (ATP) gated Ca2+ and Na+ conductance channels, where the stoichiometry is the removal of one Ca2+ for the hydrolysis of one ATP molecule. Two unique sets of model parameters were determined using an evolutionary algorithm to optimise fitting to experimental data for each of the receptors. This allows the proposed model to capture both human P2X7 and P2X4 data (hP2X7 and hP2X4). The model architecture enables a high degree of simplicity, accuracy and predictability of Ca2+ and Na+ dynamics thus providing quantitative insights into different behaviours of intracellular Na+ and Ca2+ which will guide future experimental research. Understanding the interactions between these receptors and other membrane-bound transporters provides a step forward in resolving the qualitative link between purinergic receptors and microglial physiology and their contribution to brain pathology. Mathematical modelling and computer simulation are powerful tools by which we can analyse complex biological systems, particularly, neural phenomena involved in brain dysfunction. In this research, we develop a theoretical foundation for studying P2X-mediated calcium and sodium signalling in human microglial cells. Microglia, which are brain-resident macrophages, restructure their intracellular actin cytoskeleton to enable motility; this restructuring requires a complex molecular cascade involving a set of ionic channels, membrane-coupled receptors and cytosolic components. Recent studies highlight the importance for increasing our understanding of microglia physiology, since their functions play critical roles in both normal physiological and pathological dynamics of the brain. There is a need to develop reliable human cellular models to investigate the biology of microglia aimed at understanding the influence of purinergic signalling in brain dysfunction to provide novel drug discovery targets. In this work, a detailed mathematical model is built for the dynamics of human P2XRs in microglia. Subsequently, experimental whole-cell currents are used to derive P2X-mediated electrophysiology of human microglia (i.e. sodium and calcium dynamics, and membrane potential). Our predictions reveal new quantitative insights into P2XRs on how they regulate ionic concentrations in terms of physiological interactions and transient responses.
Collapse
Affiliation(s)
- Alireza Poshtkohi
- School of Computing, Engineering and Intelligent Systems, Ulster University, Londonderry, United Kingdom
- * E-mail:
| | - John Wade
- School of Computing, Engineering and Intelligent Systems, Ulster University, Londonderry, United Kingdom
| | - Liam McDaid
- School of Computing, Engineering and Intelligent Systems, Ulster University, Londonderry, United Kingdom
| | - Junxiu Liu
- School of Computing, Engineering and Intelligent Systems, Ulster University, Londonderry, United Kingdom
| | - Mark Dallas
- School of Pharmacy, University of Reading, Reading, United Kingdom
| | - Angela Bithell
- School of Pharmacy, University of Reading, Reading, United Kingdom
| |
Collapse
|
3
|
Fannon OM, Bithell A, Whalley BJ, Delivopoulos E. A Fiber Alginate Co-culture Platform for the Differentiation of mESC and Modeling of the Neural Tube. Front Neurosci 2021; 14:524346. [PMID: 33510605 PMCID: PMC7835723 DOI: 10.3389/fnins.2020.524346] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 12/04/2020] [Indexed: 12/28/2022] Open
Abstract
Alginate hydrogels are a commonly used substrate for in vitro 3D cell culture. These naturally derived biomaterials are highly tunable, biocompatible, and can be designed to mimic the elastic modulus of the adult brain at 1% w/v solution. Recent studies show that the molecular weight of the alginate can affect cell viability and differentiation. The relationship between the molecular weight, viscosity and ratio of G:M monomers of alginate hydrogels is complex, and the balance between these factors must be carefully considered when deciding on a suitable alginate hydrogel for stem cell research. This study investigates the formation of embryoid bodies (EB) from mouse embryonic stem cells, using low molecular weight (LMW) and high molecular weight (HMW) alginates. The cells are differentiated using a retinoic acid-based protocol, and the resulting aggregates are sectioned and stained for the presence of stem cells and the three germ layers (endoderm, mesoderm, and ectoderm). The results highlight that aggregates within LMW and HMW alginate are true EBs, as demonstrated by positive staining for markers of the three germ layers. Using tubular alginate scaffolds, formed with an adapted gradient maker protocol, we also propose a novel 3D platform for the patterned differentiation of mESCs, based on gradients of retinoic acid produced in situ by lateral motor column (LMC) motor neurons. The end product of our platform will be of great interest as it can be further developed into a powerful model of neural tube development.
Collapse
Affiliation(s)
- Orla M Fannon
- School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Angela Bithell
- School of Pharmacy, University of Reading, Reading, United Kingdom
| | | | | |
Collapse
|
4
|
Wade JJ, Breslin K, Wong-Lin K, Harkin J, Flanagan B, Van Zalinge H, Hall S, Dallas M, Bithell A, Verkhratsky A, McDaid L. Calcium Microdomain Formation at the Perisynaptic Cradle Due to NCX Reversal: A Computational Study. Front Cell Neurosci 2019; 13:185. [PMID: 31133809 PMCID: PMC6513884 DOI: 10.3389/fncel.2019.00185] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 04/12/2019] [Indexed: 01/06/2023] Open
Abstract
It has recently been proposed using a multi-compartmental mathematical model that negatively fixed charged membrane-associated sites constrain the flow of cations in perisynaptic astroglial processes. This restricted movement of ions between the perisynaptic cradle (PsC), principal astroglial processes and the astrocyte soma gives rise to potassium (K+) and sodium (Na+) microdomains at the PsC. The present paper extends the above model to demonstrate that the formation of an Na+ microdomain can reverse the Na+/Ca2+ exchanger (NCX) thus providing an additional source of calcium (Ca2+) at the PsC. Results presented clearly show that reversal of the Na+/Ca2+ exchanger is instigated by a glutamate transporter coupled increase in concentration of cytoplasmic [Na+]i at the PsC, which and instigates Ca2+ influx through the NCX. As the flow of Ca2+ along the astrocyte process and away from the PsC is also constrained by Ca2+ binding proteins, then a Ca2+ microdomain forms at the PsC. The paper also serves to demonstrate that the EAAT, NKA, and NCX represent the minimal requirement necessary and sufficient for the development of a Ca2+ microdomain and that these mechanisms directly link neuronal activity and glutamate release to the formation of localized Na+ and Ca2+ microdomains signals at the PsC. This local source of Ca2+ can provide a previously underexplored form of astroglial Ca2+ signaling.
Collapse
Affiliation(s)
- John Joseph Wade
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - Kevin Breslin
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - KongFatt Wong-Lin
- Neural Systems and Neurotechnology Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - Jim Harkin
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - Bronac Flanagan
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - Harm Van Zalinge
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom
| | - Steve Hall
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom
| | - Mark Dallas
- Reading School of Pharmacy, University of Reading, Reading, United Kingdom
| | - Angela Bithell
- Reading School of Pharmacy, University of Reading, Reading, United Kingdom
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Liam McDaid
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| |
Collapse
|
5
|
Kang S, Hayashi Y, Bruyns-Haylett M, Baker DH, Boura M, Wang X, Karatzas KA, Serra I, Bithell A, Williams C, Field DT, Zheng Y. Supplemental Vitamin B-12 Enhances the Neural Response to Sensory Stimulation in the Barrel Cortex of Healthy Rats but Does Not Affect Spontaneous Neural Activity. J Nutr 2019; 149:730-737. [PMID: 31006816 DOI: 10.1093/jn/nxz011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 12/07/2018] [Accepted: 01/17/2019] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Although vitamin B-12 (B-12) is known to contribute to the structural and functional development of the brain, it is unclear if B-12 supplementation has any beneficial effect in healthy populations in terms of enhanced neurologic status of the brain or improved cognitive function. OBJECTIVES We investigated the effect of dietary supplementation of B-12 on the cortical neural activity of well-nourished young adult rats and tested the hypothesis that B-12 supplementation in healthy rats may reduce sensory-evoked neural activity due to enhanced inhibition. METHODS Female Lister Hooded rats weighing 190-265 g (2-4 mo old) were included in the study. The experimental group was fed with B-12 (cyanocobalamin)-enriched water at a concentration of 1 mg/L, and the control (CON) group with tap water for 3 wk. Animals were then anesthetized and cortical neural responses to whisker stimulation were recorded in vivo through the use of a multichannel microelectrode, from which local field potentials (LFPs) were extracted. RESULTS Somatosensory-evoked LFP was 25% larger in the B-12 group (4.13 ± 0.24 mV) than in the CON group (3.30 ± 0.21 mV) (P = 0.02). Spontaneous neural activity did not differ between groups; frequency spectra at each frequency bin of interest did not pass the cluster-forming threshold at the 5% significance level. CONCLUSIONS These findings do not provide evidence supporting the hypothesis of decreased neural activity due to B-12 supplementation. As the spontaneous neural activity was unaffected, the increase in somatosensory-evoked LFP may be due to enhanced afferent signal reaching the barrel cortex from the whisker pad, indicating that B-12-supplemented rats may have enhanced sensitivity to sensory stimulation compared with the CON group. We suggest that this enhancement might be the result of lowered sensory threshold, although the underlying mechanism has yet to be elucidated.
Collapse
Affiliation(s)
- Sungmin Kang
- Biomedical Engineering, School of Biological Sciences.,Centre for Integrative Neuroscience and Neurodynamics (CINN), University of Reading, Reading, United Kingdom
| | - Yurie Hayashi
- Biomedical Engineering, School of Biological Sciences
| | | | - Daniel H Baker
- Department of Psychology and York Biomedical Research Institute, University of York, York, United Kingdom
| | | | | | - Kimon-Andreas Karatzas
- Food and Nutritional Sciences.,Centre for Integrative Neuroscience and Neurodynamics (CINN), University of Reading, Reading, United Kingdom
| | - Ines Serra
- Pharmacy, School of Chemistry, Food and Pharmacy
| | | | - Claire Williams
- Psychology, School of Psychology and Clinical Language Sciences
| | - David T Field
- Centre for Integrative Neuroscience and Neurodynamics (CINN), University of Reading, Reading, United Kingdom
| | - Ying Zheng
- Biomedical Engineering, School of Biological Sciences.,Centre for Integrative Neuroscience and Neurodynamics (CINN), University of Reading, Reading, United Kingdom
| |
Collapse
|
6
|
Centeno EGZ, Cimarosti H, Bithell A. 2D versus 3D human induced pluripotent stem cell-derived cultures for neurodegenerative disease modelling. Mol Neurodegener 2018; 13:27. [PMID: 29788997 PMCID: PMC5964712 DOI: 10.1186/s13024-018-0258-4] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 05/08/2018] [Indexed: 12/11/2022] Open
Abstract
Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS), affect millions of people every year and so far, there are no therapeutic cures available. Even though animal and histological models have been of great aid in understanding disease mechanisms and identifying possible therapeutic strategies, in order to find disease-modifying solutions there is still a critical need for systems that can provide more predictive and physiologically relevant results. One possible avenue is the development of patient-derived models, e.g. by reprogramming patient somatic cells into human induced pluripotent stem cells (hiPSCs), which can then be differentiated into any cell type for modelling. These systems contain key genetic information from the donors, and therefore have enormous potential as tools in the investigation of pathological mechanisms underlying disease phenotype, and progression, as well as in drug testing platforms. hiPSCs have been widely cultured in 2D systems, but in order to mimic human brain complexity, 3D models have been proposed as a more advanced alternative. This review will focus on the use of patient-derived hiPSCs to model AD, PD, HD and ALS. In brief, we will cover the available stem cells, types of 2D and 3D culture systems, existing models for neurodegenerative diseases, obstacles to model these diseases in vitro, and current perspectives in the field.
Collapse
Affiliation(s)
- Eduarda G Z Centeno
- Department of Biotechnology, Federal University of Pelotas, Campus Capão do Leão, Pelotas, RS, 96160-000, Brazil.,Department of Pharmacology, Federal University of Santa Catarina, Campus Trindade, Florianópolis, SC, 88040-900, Brazil
| | - Helena Cimarosti
- Department of Pharmacology, Federal University of Santa Catarina, Campus Trindade, Florianópolis, SC, 88040-900, Brazil.
| | - Angela Bithell
- School of Pharmacy, University of Reading, Whiteknights Campus, Reading, RG6 6UB, UK.
| |
Collapse
|
7
|
Bhinge A, Namboori SC, Bithell A, Soldati C, Buckley NJ, Stanton LW. MiR-375 is Essential for Human Spinal Motor Neuron Development and May Be Involved in Motor Neuron Degeneration. Stem Cells 2016; 34:124-134. [DOI: 10.1002/stem.2233] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
Abstract
The transcription factor REST is a key suppressor of neuronal genes in non-neuronal tissues. REST has been shown to suppress proneuronal microRNAs in neural progenitors indicating that REST-mediated neurogenic suppression may act in part via microRNAs. We used neural differentiation of Rest-null mouse ESC to identify dozens of microRNAs regulated by REST during neural development. One of the identified microRNAs, miR-375, was upregulated during human spinal motor neuron development. We found that miR-375 facilitates spinal motor neurogenesis by targeting the cyclin kinase CCND2 and the transcription factor PAX6. Additionally, miR-375 inhibits the tumor suppressor p53 and protects neurons from apoptosis in response to DNA damage. Interestingly, motor neurons derived from a spinal muscular atrophy patient displayed depressed miR-375 expression and elevated p53 protein levels. Importantly, SMA motor neurons were significantly more susceptible to DNA damage induced apoptosis suggesting that miR-375 may play a protective role in motor neurons.
Collapse
Affiliation(s)
- Akshay Bhinge
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Singapore, Singapore
| | - Seema C. Namboori
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Singapore, Singapore
| | - Angela Bithell
- Department of Neuroscience, Centre for the Cellular Basis of Behaviour, Institute of Psychiatry, King's College London, London, UK
| | - Chiara Soldati
- Department of Neuroscience, Centre for the Cellular Basis of Behaviour, Institute of Psychiatry, King's College London, London, UK
| | - Noel J. Buckley
- Department of Psychiatry, University of Oxford, Warneford Hospital, Headington, Oxford, United Kingdom
| | - Lawrence W. Stanton
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| |
Collapse
|
8
|
Smith I, Haag M, Ugbode C, Tams D, Rattray M, Przyborski S, Bithell A, Whalley BJ. Neuronal-glial populations form functional networks in a biocompatible 3D scaffold. Neurosci Lett 2015; 609:198-202. [DOI: 10.1016/j.neulet.2015.10.044] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 10/06/2015] [Accepted: 10/14/2015] [Indexed: 11/30/2022]
|
9
|
Soldati C, Caramanica P, Burney MJ, Toselli C, Bithell A, Augusti-Tocco G, Stanton LW, Biagioni S, Buckley NJ, Cacci E. RE1 silencing transcription factor/neuron-restrictive silencing factor regulates expansion of adult mouse subventricular zone-derived neural stem/progenitor cells in vitro. J Neurosci Res 2015. [DOI: 10.1002/jnr.23613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Chiara Soldati
- Department of Biology and Biotechnology “Charles Darwin,” Sapienza University of Rome; Rome Italy
- Istituto Pasteur Fondazione Cenci Bolognetti; Sapienza University of Rome; Rome Italy
| | - Pasquale Caramanica
- Department of Biology and Biotechnology “Charles Darwin,” Sapienza University of Rome; Rome Italy
| | - Matthew J. Burney
- Department of Neuroscience; Centre for the Cellular Basis of Behaviour; Institute of Psychiatry; King's College London; London United Kingdom
| | - Camilla Toselli
- Department of Biology and Biotechnology “Charles Darwin,” Sapienza University of Rome; Rome Italy
- Center for Life Nanoscience Sapienza; Istituto Italiano di Tecnologia; Rome Italy
| | - Angela Bithell
- Department of Neuroscience; Centre for the Cellular Basis of Behaviour; Institute of Psychiatry; King's College London; London United Kingdom
| | - Gabriella Augusti-Tocco
- Department of Biology and Biotechnology “Charles Darwin,” Sapienza University of Rome; Rome Italy
| | | | - Stefano Biagioni
- Department of Biology and Biotechnology “Charles Darwin,” Sapienza University of Rome; Rome Italy
- Center for Life Nanoscience Sapienza; Istituto Italiano di Tecnologia; Rome Italy
| | - Noel J. Buckley
- Department of Psychiatry; University of Oxford, Warneford Hospital; Oxford United Kingdom
| | - Emanuele Cacci
- Department of Biology and Biotechnology “Charles Darwin,” Sapienza University of Rome; Rome Italy
- Istituto Pasteur Fondazione Cenci Bolognetti; Sapienza University of Rome; Rome Italy
| |
Collapse
|
10
|
Raposo AASF, Vasconcelos FF, Drechsel D, Marie C, Johnston C, Dolle D, Bithell A, Gillotin S, van den Berg DLC, Ettwiller L, Flicek P, Crawford GE, Parras CM, Berninger B, Buckley NJ, Guillemot F, Castro DS. Ascl1 Coordinately Regulates Gene Expression and the Chromatin Landscape during Neurogenesis. Cell Rep 2015; 10:1544-1556. [PMID: 25753420 PMCID: PMC5383937 DOI: 10.1016/j.celrep.2015.02.025] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 01/14/2015] [Accepted: 02/05/2015] [Indexed: 01/02/2023] Open
Abstract
The proneural transcription factor Ascl1 coordinates gene expression in both proliferating and differentiating progenitors along the neuronal lineage. Here, we used a cellular model of neurogenesis to investigate how Ascl1 interacts with the chromatin landscape to regulate gene expression when promoting neuronal differentiation. We find that Ascl1 binding occurs mostly at distal enhancers and is associated with activation of gene transcription. Surprisingly, the accessibility of Ascl1 to its binding sites in neural stem/progenitor cells remains largely unchanged throughout their differentiation, as Ascl1 targets regions of both readily accessible and closed chromatin in proliferating cells. Moreover, binding of Ascl1 often precedes an increase in chromatin accessibility and the appearance of new regions of open chromatin, associated with de novo gene expression during differentiation. Our results reveal a function of Ascl1 in promoting chromatin accessibility during neurogenesis, linking the chromatin landscape at Ascl1 target regions with the temporal progression of its transcriptional program. Genome-wide binding of Ascl1 correlates with transcription activation Ascl1 can bind to both open and closed chromatin in proliferating cells Ascl1 promotes local chromatin accessibility at its target sites Chromatin dynamics at Ascl1 sites regulates temporal progression of its program
Collapse
Affiliation(s)
| | | | | | - Corentine Marie
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC University Paris 06, UMR-S 1127, Institut du Cerveau et de la Moelle Épinière, ICM, 75013 Paris, France
| | - Caroline Johnston
- Centre for the Cellular Basis of Behavior, Institute of Psychiatry, King's College London, London SE5 9NU, UK
| | - Dirk Dolle
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK; Wellcome Trust Sanger Institute, Welcome Trust Genome Campus, Cambridge CB10 1SA, UK
| | - Angela Bithell
- University of Reading, School of Pharmacy, Hopkins Life Sciences Building, Reading RG6 6AP, UK
| | | | | | - Laurence Ettwiller
- Centre for Organismal Studies (COS), Ruprecht-Karls-University, 69120 Heidelberg, Germany
| | - Paul Flicek
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK; Wellcome Trust Sanger Institute, Welcome Trust Genome Campus, Cambridge CB10 1SA, UK
| | - Gregory E Crawford
- Institute of Genome Sciences & Policy, Duke University, Durham, NC 27708, USA
| | - Carlos M Parras
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC University Paris 06, UMR-S 1127, Institut du Cerveau et de la Moelle Épinière, ICM, 75013 Paris, France
| | - Benedikt Berninger
- Institute of Physiological Chemistry, University Medical Center Johannes Gutenberg University Mainz, 55128 Mainz, Germany; Department of Physiological Genomics, Institute of Physiology, Ludwig-Maximilians University Munich, 80336 Munich, Germany
| | - Noel J Buckley
- Department of Psychiatry, University of Oxford, Oxford OX3 7JX, UK
| | | | - Diogo S Castro
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal.
| |
Collapse
|
11
|
Soldati C, Caramanica P, Burney MJ, Toselli C, Bithell A, Augusti-Tocco G, Stanton LW, Biagioni S, Buckley NJ, Cacci E. RE1 silencing transcription factor/neuron-restrictive silencing factor regulates expansion of adult mouse subventricular zone-derived neural stem/progenitor cells in vitro. J Neurosci Res 2015; 93:1203-14. [PMID: 25691247 DOI: 10.1002/jnr.23572] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Revised: 12/03/2014] [Accepted: 01/27/2015] [Indexed: 12/21/2022]
Abstract
Adult neural stem cell (aNSC) activity is tuned by external stimuli through the recruitment of transcription factors. This study examines the RE1 silencing transcription factor (REST) in neural stem/progenitor cells isolated from the subventricular zone of adult mouse brain and provides the first extensive characterization of REST-mediated control of the cellular and molecular properties. This study shows that REST knockdown affects the capacity of progenitor cells to generate neurospheres, reduces cell proliferation, and triggers cell differentiation despite the presence of growth factors. Genome- and transcriptome-wide analyses show that REST binding sites are significantly enriched in genes associated with synaptic transmission and nervous system development and function. Seeking candidate regulators of aNSC function, this study identifies a member of the bone morphogenetic protein (BMP) family, BMP6, the mRNA and protein of which increased after REST knockdown. The results of this study extend previous findings, demonstrating a reciprocal control of REST expression by BMPs. Administration of exogenous BMP6 inhibits aNSC proliferation and induces the expression of the astrocytic marker glial fibrillary acidic protein, highlighting its antimitogenic and prodifferentiative effects. This study suggests that BMP6 produced in a REST-regulated manner together with other signals can contribute to regulation of NSC maintenance and fate.
Collapse
Affiliation(s)
- Chiara Soldati
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University of Rome, Rome, Italy.,Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - Pasquale Caramanica
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University of Rome, Rome, Italy
| | - Matthew J Burney
- Department of Neuroscience, Centre for the Cellular Basis of Behaviour, Institute of Psychiatry, King's College London, London, United Kingdom
| | - Camilla Toselli
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University of Rome, Rome, Italy.,Center for Life Nanoscience Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Angela Bithell
- Department of Neuroscience, Centre for the Cellular Basis of Behaviour, Institute of Psychiatry, King's College London, London, United Kingdom
| | - Gabriella Augusti-Tocco
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University of Rome, Rome, Italy
| | | | - Stefano Biagioni
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University of Rome, Rome, Italy.,Center for Life Nanoscience Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Noel J Buckley
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom
| | - Emanuele Cacci
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University of Rome, Rome, Italy.,Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| |
Collapse
|
12
|
Burney MJ, Johnston C, Wong KY, Teng SW, Beglopoulos V, Stanton LW, Williams BP, Bithell A, Buckley NJ. An epigenetic signature of developmental potential in neural stem cells and early neurons. Stem Cells 2014; 31:1868-80. [PMID: 23712654 DOI: 10.1002/stem.1431] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 04/09/2013] [Accepted: 04/22/2013] [Indexed: 01/30/2023]
Abstract
A cardinal property of neural stem cells (NSCs) is their ability to adopt multiple fates upon differentiation. The epigenome is widely seen as a read-out of cellular potential and a manifestation of this can be seen in embryonic stem cells (ESCs), where promoters of many lineage-specific regulators are marked by a bivalent epigenetic signature comprising trimethylation of both lysine 4 and lysine 27 of histone H3 (H3K4me3 and H3K27me3, respectively). Bivalency has subsequently emerged as a powerful epigenetic indicator of stem cell potential. Here, we have interrogated the epigenome during differentiation of ESC-derived NSCs to immature GABAergic interneurons. We show that developmental transitions are accompanied by loss of bivalency at many promoters in line with their increasing developmental restriction from pluripotent ESC through multipotent NSC to committed GABAergic interneuron. At the NSC stage, the promoters of genes encoding many transcriptional regulators required for differentiation of multiple neuronal subtypes and neural crest appear to be bivalent, consistent with the broad developmental potential of NSCs. Upon differentiation to GABAergic neurons, all non-GABAergic promoters resolve to H3K27me3 monovalency, whereas GABAergic promoters resolve to H3K4me3 monovalency or retain bivalency. Importantly, many of these epigenetic changes occur before any corresponding changes in gene expression. Intriguingly, another group of gene promoters gain bivalency as NSCs differentiate toward neurons, the majority of which are associated with functions connected with maturation and establishment and maintenance of connectivity. These data show that bivalency provides a dynamic epigenetic signature of developmental potential in both NSCs and in early neurons.
Collapse
Affiliation(s)
- Matthew J Burney
- Centre for the Cellular Basis of Behaviour, Department of Neuroscience, Institute of Psychiatry, King's College London, James Black Centre, London, United Kingdom
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Soldati C, Bithell A, Johnston C, Wong KY, Stanton LW, Buckley NJ. Dysregulation of REST-regulated coding and non-coding RNAs in a cellular model of Huntington's disease. J Neurochem 2013; 124:418-30. [PMID: 23145961 DOI: 10.1111/jnc.12090] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 11/08/2012] [Accepted: 11/08/2012] [Indexed: 12/12/2022]
Abstract
Huntingtin (Htt) protein interacts with many transcriptional regulators, with widespread disruption to the transcriptome in Huntington's disease (HD) brought about by altered interactions with the mutant Htt (muHtt) protein. Repressor Element-1 Silencing Transcription Factor (REST) is a repressor whose association with Htt in the cytoplasm is disrupted in HD, leading to increased nuclear REST and concomitant repression of several neuronal-specific genes, including brain-derived neurotrophic factor (Bdnf). Here, we explored a wide set of HD dysregulated genes to identify direct REST targets whose expression is altered in a cellular model of HD but that can be rescued by knock-down of REST activity. We found many direct REST target genes encoding proteins important for nervous system development, including a cohort involved in synaptic transmission, at least two of which can be rescued at the protein level by REST knock-down. We also identified several microRNAs (miRNAs) whose aberrant repression is directly mediated by REST, including miR-137, which has not previously been shown to be a direct REST target in mouse. These data provide evidence of the contribution of inappropriate REST-mediated transcriptional repression to the widespread changes in coding and non-coding gene expression in a cellular model of HD that may affect normal neuronal function and survival.
Collapse
Affiliation(s)
- Chiara Soldati
- Department of Neuroscience, Centre for the Cellular Basis of Behaviour, Institute of Psychiatry, King's College London, London, UK
| | | | | | | | | | | |
Collapse
|
14
|
Abstract
Acquisition and maintenance of cell fate and potential are dependent on the complex interplay of extracellular signaling, gene regulatory networks and epigenetic states. During embryonic development, embryonic stem cells become progressively more restricted along specific lineages, ultimately giving rise to the diversity of cell types in the adult mammalian organism. Recent years have seen major advances in our understanding of the mechanisms that regulate the underlying transcriptional programmes during development. In particular, there has been a significant increase in our knowledge of how epigenetic marks on chromatin can regulate transcription by generating more or less permissive chromatin conformations. This article focuses on how a single transcription factor, repressor element-1 silencing transcription factor, can function as both a transcriptional and epigenetic regulator, controlling diverse aspects of development. We will discuss how the elucidation of repressor element-1 silencing transcription factor function in both normal and disease conditions has provided valuable insights into how the epigenome and transcriptional regulators might cooperatively orchestrate correct development.
Collapse
Affiliation(s)
- Angela Bithell
- King's College London, Institute of Psychiatry, Department of Neuroscience, Centre for the Cellular Basis of Behaviour, The James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK.
| |
Collapse
|
15
|
Soldati C, Bithell A, Johnston C, Wong KY, Teng SW, Beglopoulos V, Stanton LW, Buckley NJ. Repressor Element 1 Silencing Transcription Factor Couples Loss of Pluripotency with Neural Induction and Neural Differentiation. Stem Cells 2012; 30:425-34. [DOI: 10.1002/stem.1004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
16
|
Castro DS, Martynoga B, Parras C, Ramesh V, Pacary E, Johnston C, Drechsel D, Lebel-Potter M, Garcia LG, Hunt C, Dolle D, Bithell A, Ettwiller L, Buckley N, Guillemot F. A novel function of the proneural factor Ascl1 in progenitor proliferation identified by genome-wide characterization of its targets. Genes Dev 2011; 25:930-45. [PMID: 21536733 DOI: 10.1101/gad.627811] [Citation(s) in RCA: 299] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Proneural genes such as Ascl1 are known to promote cell cycle exit and neuronal differentiation when expressed in neural progenitor cells. The mechanisms by which proneural genes activate neurogenesis--and, in particular, the genes that they regulate--however, are mostly unknown. We performed a genome-wide characterization of the transcriptional targets of Ascl1 in the embryonic brain and in neural stem cell cultures by location analysis and expression profiling of embryos overexpressing or mutant for Ascl1. The wide range of molecular and cellular functions represented among these targets suggests that Ascl1 directly controls the specification of neural progenitors as well as the later steps of neuronal differentiation and neurite outgrowth. Surprisingly, Ascl1 also regulates the expression of a large number of genes involved in cell cycle progression, including canonical cell cycle regulators and oncogenic transcription factors. Mutational analysis in the embryonic brain and manipulation of Ascl1 activity in neural stem cell cultures revealed that Ascl1 is indeed required for normal proliferation of neural progenitors. This study identified a novel and unexpected activity of the proneural gene Ascl1, and revealed a direct molecular link between the phase of expansion of neural progenitors and the subsequent phases of cell cycle exit and neuronal differentiation.
Collapse
Affiliation(s)
- Diogo S Castro
- Medical Research Council National Institute for Medical Research, Division of Molecular Neurobiology, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Soldati C, Bithell A, Conforti P, Cattaneo E, Buckley NJ. Rescue of gene expression by modified REST decoy oligonucleotides in a cellular model of Huntington's disease. J Neurochem 2010; 116:415-25. [PMID: 21105876 DOI: 10.1111/j.1471-4159.2010.07122.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Transcriptional dysfunction is a prominent hallmark of Huntington's disease (HD). Several transcription factors have been implicated in the aetiology of HD progression and one of the most prominent is repressor element 1 (RE1) silencing transcription factor (REST). REST is a global repressor of neuronal gene expression and in the presence of mutant Huntingtin increased nuclear REST levels lead to elevated RE1 occupancy and a concomitant increase in target gene repression, including brain-derived neurotrophic factor. It is of great interest to devise strategies to reverse transcriptional dysregulation caused by increased nuclear REST and determine the consequences in HD. Thus far, such strategies have involved RNAi or mutant REST constructs. Decoys are double-stranded oligodeoxynucleotides corresponding to the DNA-binding element of a transcription factor and act to sequester it, thereby abrogating its transcriptional activity. Here, we report the use of a novel decoy strategy to rescue REST target gene expression in a cellular model of HD. We show that delivery of the decoy in cells expressing mutant Huntingtin leads to its specific interaction with REST, a reduction in REST occupancy of RE1s and rescue of target gene expression, including Bdnf. These data point to an alternative strategy for rebalancing the transcriptional dysregulation in HD.
Collapse
Affiliation(s)
- Chiara Soldati
- Department of Neuroscience and Centre for the Cellular Basis of Behaviour, Institute of Psychiatry, King's College London, The James Black Centre, London, UK
| | | | | | | | | |
Collapse
|
18
|
Bithell A, Hsu T, Kandanearatchi A, Landau S, Everall IP, Tsuang MT, Chana G, Williams BP. Expression of the Rap1 guanine nucleotide exchange factor, MR-GEF, is altered in individuals with bipolar disorder. PLoS One 2010; 5:e10392. [PMID: 20436929 PMCID: PMC2861006 DOI: 10.1371/journal.pone.0010392] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 03/03/2010] [Indexed: 11/18/2022] Open
Abstract
In the rodent forebrain GABAergic neurons are generated from progenitor cells that express the transcription factors Dlx1 and Dlx2. The Rap-1 guanine nucleotide exchange factor, MR-GEF, is turned on by many of these developing GABAergic neurons. Expression of both Dlx1/2 and MR-GEF is retained in both adult mouse and human forebrain where, in human, decreased Dlx1 expression has been associated with psychosis. Using in situ hybridization studies we show that MR-GEF expression is significantly down-regulated in the forebrain of Dlx1/2 double mutant mice suggesting that MR-GEF and Dlx1/2 form part of a common signalling pathway during GABAergic neuronal development. We therefore compared MR-GEF expression by in situ hybridization in individuals with major psychiatric disorders (schizophrenia, bipolar disorder, major depression) and control individuals. We observed a significant positive correlation between layers II and IV of the dorso-lateral prefrontal cortex (DLPFC) in the percentage of MR-GEF expressing neurons in individuals with bipolar disorder, but not in individuals with schizophrenia, major depressive disorder or in controls. Since MR-GEF encodes a Rap1 GEF able to activate G-protein signalling, we suggest that changes in MR-GEF expression could potentially influence neurotransmission.
Collapse
Affiliation(s)
- Angela Bithell
- Department of Psychological Medicine, Institute of Psychiatry, King's College London, London, United Kingdom
| | - Tony Hsu
- Center for Behavioral Genomics, Department of Psychiatry, University of California San Diego, San Diego, California, United States of America
| | - Apsara Kandanearatchi
- Department of Psychological Medicine, Institute of Psychiatry, King's College London, London, United Kingdom
| | - Sabine Landau
- Department of Biostatistics and Computing, Institute of Psychiatry, King's College London, London, United Kingdom
| | - Ian P. Everall
- Department of Psychological Medicine, Institute of Psychiatry, King's College London, London, United Kingdom
- Center for Behavioral Genomics, Department of Psychiatry, University of California San Diego, San Diego, California, United States of America
| | - Ming T. Tsuang
- Center for Behavioral Genomics, Department of Psychiatry, University of California San Diego, San Diego, California, United States of America
| | - Gursharan Chana
- Department of Psychological Medicine, Institute of Psychiatry, King's College London, London, United Kingdom
- Center for Behavioral Genomics, Department of Psychiatry, University of California San Diego, San Diego, California, United States of America
| | - Brenda P. Williams
- Department of Psychological Medicine, Institute of Psychiatry, King's College London, London, United Kingdom
- * E-mail:
| |
Collapse
|
19
|
Buckley NJ, Johnson R, Zuccato C, Bithell A, Cattaneo E. The role of REST in transcriptional and epigenetic dysregulation in Huntington's disease. Neurobiol Dis 2010; 39:28-39. [PMID: 20170730 DOI: 10.1016/j.nbd.2010.02.003] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Revised: 02/08/2010] [Accepted: 02/09/2010] [Indexed: 12/20/2022] Open
Abstract
Huntington's disease (HD) is a devastating disorder that affects approximately 1 in 10,000 people and is accompanied by neuronal dysfunction and neurodegeneration. HD manifests as a progressive chorea, a decline in mental abilities accompanied by behavioural, emotional and psychiatric problems followed by, dementia, and ultimately, death. The molecular pathology of HD is complex but includes widespread transcriptional dysregulation. Although many transcriptional regulatory molecules have been implicated in the pathogenesis of HD, a growing body of evidence points to the pivotal role of RE1 Silencing Transcription Factor (REST). In HD, REST, translocates from the cytoplasm to the nucleus in neurons resulting in repression of key target genes such as BDNF. Since these original observations, several thousand direct target genes of REST have been identified, including numerous non-coding RNAs including both microRNAs and long non-coding RNAs, several of which are dysregulated in HD. More recently, evidence is emerging that hints at epigenetic abnormalities in HD brain. This in turn, promotes the notion that targeting the epigenetic machinery may be a useful strategy for treatment of some aspects of HD. REST also recruits a host of histone and chromatin modifying activities that can regulate the local epigenetic signature at REST target genes. Collectively, these observations present REST as a hub that coordinates transcriptional, posttranscriptional and epigenetic programmes, many of which are disrupted in HD. We identify several spokes emanating from this REST hub that may represent useful sites to redress REST dysfunction in HD.
Collapse
Affiliation(s)
- Noel J Buckley
- King's College London, Institute of Psychiatry, Centre for the Cellular Basis of Behaviour, James Black Centre, 125 Coldharbour Lane, London SE5 9NU, UK.
| | | | | | | | | |
Collapse
|
20
|
Bithell A, Finch SE, Hornby MF, Williams BP. Fibroblast growth factor 2 maintains the neurogenic capacity of embryonic neural progenitor cells in vitro but changes their neuronal subtype specification. Stem Cells 2008; 26:1565-74. [PMID: 18339769 DOI: 10.1634/stemcells.2007-0832] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Many in vitro systems used to examine multipotential neural progenitor cells (NPCs) rely on mitogens including fibroblast growth factor 2 (FGF2) for their continued expansion. However, FGF2 has also been shown to alter the expression of transcription factors (TFs) that determine cell fate. Here, we report that NPCs from the embryonic telencephalon grown without FGF2 retain many of their in vivo characteristics, making them a good model for investigating molecular mechanisms involved in cell fate specification and differentiation. However, exposure of cortical NPCs to FGF2 results in a profound change in the types of neurons generated, switching them from a glutamatergic to a GABAergic phenotype. This change closely correlates with the dramatic upregulation of TFs more characteristic of ventral telencephalic NPCs. In addition, exposure of cortical NPCs to FGF2 maintains their neurogenic potential in vitro, and NPCs spontaneously undergo differentiation following FGF2 withdrawal. These results highlight the importance of TFs in determining the types of neurons generated by NPCs in vitro. In addition, they show that FGF2, as well as acting as a mitogen, changes the developmental capabilities of NPCs. These findings have implications for the cell fate specification of in vitro-expanded NPCs and their ability to generate specific cell types for therapeutic applications. Disclosure of potential conflicts of interest is found at the end of this article.
Collapse
Affiliation(s)
- Angela Bithell
- Centre for the Cellular Basis of Behaviour, MRC Centre for Neurodegeneration Research, The James Black Centre, King's College London, Institute of Psychiatry, 125 Coldharbour Lane, London SE5 9NU, United Kingdom
| | | | | | | |
Collapse
|
21
|
Abstract
The past few years have seen major advances in the field of NSC (neural stem cell) research with increasing emphasis towards its application in cell-replacement therapy for neurological disorders. However, the clinical application of NSCs will remain largely unfeasible until a comprehensive understanding of the cellular and molecular mechanisms of NSC fate specification is achieved. With this understanding will come an increased possibility to exploit the potential of stem cells in order to manufacture transplantable NSCs able to provide a safe and effective therapy for previously untreatable neurological disorders. Since the pathology of each of these disorders is determined by the loss or damage of a specific neural cell population, it may be necessary to generate a range of NSCs able to replace specific neurons or glia rather than generating a generic NSC population. Currently, a diverse range of strategies is being investigated with this goal in mind. In this review, we focus on the relationship between NSC specification and differentiation and discuss how this information may be used to direct NSCs towards a particular fate.
Collapse
Affiliation(s)
- Angela Bithell
- Institute of Psychiatry, Department of Psychological Medicine, PO Box 52, De Crespigny Park, London SE5 8AF, U.K
| | | |
Collapse
|
22
|
Bithell A, Alberta J, Hornby F, Stiles CD, Williams BP. Expression of the guanine nucleotide exchange factor, mr-gef, is regulated during the differentiation of specific subsets of telencephalic neurons. Brain Res Dev Brain Res 2003; 146:107-18. [PMID: 14643017 DOI: 10.1016/j.devbrainres.2003.09.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We have performed a screen combining subtractive hybridization with PCR to isolate genes that are regulated when neuroepithelial (NE) cells differentiate into neurons. From this screen, we have isolated a number of known genes that have not previously been associated with neurogenesis, together with several novel genes. Here we report that one of these genes, encoding a guanine nucleotide exchange factor (GEF), is regulated during the differentiation of distinct neuronal populations. We have cloned both rat and mouse GEF genes and shown that they are orthologs of the human gene, MR-GEF, which encodes a GEF that specifically activates the small GTPase, Rap1. We have therefore named the rat gene rat mr-gef (rmr-gef) and the mouse gene mouse mr-gef (mmr-gef). Here, we will collectively refer to these two rodent genes as mr-gef. Expression studies show that mr-gef is expressed by young neurons of the developing rodent CNS but not by progenitor cells in the ventricular zone (VZ). The expression pattern of mr-gef during early telencephalic neurogenesis is strikingly similar to that of GABA and the LIM homeobox gene Lhx6, a transcription factor expressed by GABAergic interneurons generated in the ventral telencephalon, some of which migrate into the cortex during development. These observations suggest that mr-gef encodes a protein that is part of a signaling pathway involved in telencephalic neurogenesis; particularly in the development of GABAergic interneurons.
Collapse
Affiliation(s)
- Angela Bithell
- Section of Experimental Neuropathology and Psychiatry, Department of Psychological Medicine, The Institute of Psychiatry (P052), De Crespigny Park, London SE5 8AF, UK
| | | | | | | | | |
Collapse
|