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Sheu SH, Upadhyayula S, Dupuy V, Pang S, Deng F, Wan J, Walpita D, Pasolli HA, Houser J, Sanchez-Martinez S, Brauchi SE, Banala S, Freeman M, Xu CS, Kirchhausen T, Hess HF, Lavis L, Li Y, Chaumont-Dubel S, Clapham DE. A serotonergic axon-cilium synapse drives nuclear signaling to alter chromatin accessibility. Cell 2022; 185:3390-3407.e18. [PMID: 36055200 PMCID: PMC9789380 DOI: 10.1016/j.cell.2022.07.026] [Citation(s) in RCA: 61] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 05/16/2022] [Accepted: 07/25/2022] [Indexed: 12/27/2022]
Abstract
Chemical synapses between axons and dendrites mediate neuronal intercellular communication. Here, we describe a synapse between axons and primary cilia: the axo-ciliary synapse. Using enhanced focused ion beam-scanning electron microscopy on samples with optimally preserved ultrastructure, we discovered synapses between brainstem serotonergic axons and the primary cilia of hippocampal CA1 pyramidal neurons. Functionally, these cilia are enriched in a ciliary-restricted serotonin receptor, the 5-hydroxytryptamine receptor 6 (5-HTR6). Using a cilia-targeted serotonin sensor, we show that opto- and chemogenetic stimulation of serotonergic axons releases serotonin onto cilia. Ciliary 5-HTR6 stimulation activates a non-canonical Gαq/11-RhoA pathway, which modulates nuclear actin and increases histone acetylation and chromatin accessibility. Ablation of this pathway reduces chromatin accessibility in CA1 pyramidal neurons. As a signaling apparatus with proximity to the nucleus, axo-ciliary synapses short circuit neurotransmission to alter the postsynaptic neuron's epigenetic state.
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Affiliation(s)
- Shu-Hsien Sheu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; Harvard Medical School, Boston, MA, USA; Boston Children's Hospital, Department of Pathology, Boston, MA, USA; Howard Huges Medical Institute, Boston Children's Hospital, Department of Cardiology, Boston, MA, USA.
| | - Srigokul Upadhyayula
- Advanced Bioimaging Center, University of California at Berkeley, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, USA; Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Vincent Dupuy
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Song Pang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Fei Deng
- School of Life Sciences, Peking University, Beijing, China
| | - Jinxia Wan
- School of Life Sciences, Peking University, Beijing, China
| | - Deepika Walpita
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - H Amalia Pasolli
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Justin Houser
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | | | - Sebastian E Brauchi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; Department of Physiology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile; Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Valdivia, Chile
| | - Sambashiva Banala
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Melanie Freeman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - C Shan Xu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Tom Kirchhausen
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, 200 Longwood Ave, Boston, MA, USA; Department of Pediatrics, Harvard Medical School, 200 Longwood Ave, Boston, MA, USA
| | - Harald F Hess
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Luke Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Yulong Li
- School of Life Sciences, Peking University, Beijing, China
| | - Séverine Chaumont-Dubel
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - David E Clapham
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; Harvard Medical School, Boston, MA, USA; Howard Huges Medical Institute, Boston Children's Hospital, Department of Cardiology, Boston, MA, USA.
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2
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Booth LC, Yao ST, Korsak A, Farmer DGS, Hood SG, McCormick D, Boesley Q, Connelly AA, McDougall SJ, Korim WS, Guild SJ, Mastitskaya S, Le P, Teschemacher AG, Kasparov S, Ackland GL, Malpas SC, McAllen RM, Allen AM, May CN, Gourine AV. Selective optogenetic stimulation of efferent fibers in the vagus nerve of a large mammal. Brain Stimul 2020; 14:88-96. [PMID: 33217609 PMCID: PMC7836098 DOI: 10.1016/j.brs.2020.11.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 10/26/2020] [Accepted: 11/11/2020] [Indexed: 12/26/2022] Open
Abstract
Background Electrical stimulation applied to individual organs, peripheral nerves, or specific brain regions has been used to treat a range of medical conditions. In cardiovascular disease, autonomic dysfunction contributes to the disease progression and electrical stimulation of the vagus nerve has been pursued as a treatment for the purpose of restoring the autonomic balance. However, this approach lacks selectivity in activating function- and organ-specific vagal fibers and, despite promising results of many preclinical studies, has so far failed to translate into a clinical treatment of cardiovascular disease. Objective Here we report a successful application of optogenetics for selective stimulation of vagal efferent activity in a large animal model (sheep). Methods and results Twelve weeks after viral transduction of a subset of vagal motoneurons, strong axonal membrane expression of the excitatory light-sensitive ion channel ChIEF was achieved in the efferent projections innervating thoracic organs and reaching beyond the level of the diaphragm. Blue laser or LED light (>10 mW mm−2; 1 ms pulses) applied to the cervical vagus triggered precisely timed, strong bursts of efferent activity with evoked action potentials propagating at speeds of ∼6 m s−1. Conclusions These findings demonstrate that in species with a large, multi-fascicled vagus nerve, it is possible to stimulate a specific sub-population of efferent fibers using light at a site remote from the vector delivery, marking an important step towards eventual clinical use of optogenetic technology for autonomic neuromodulation. Described is a method of selective efferent vagus nerve stimulation using light. Vagal preganglionic neurons are targeted to express light-sensitive channels. Specific efferent VNS by light delivery to the cervical vagus is achieved in a large animal model. Demonstrates feasibility of using optogenetic technology for autonomic neuromodulation.
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Affiliation(s)
- Lindsea C Booth
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Song T Yao
- Florey Department of Neuroscience and Mental Health, MDHS, University of Melbourne, Melbourne, Australia
| | - Alla Korsak
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - David G S Farmer
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia; Department of Physiology, The University of Melbourne, Melbourne, Australia
| | - Sally G Hood
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Daniel McCormick
- Department of Physiology and Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Quinn Boesley
- Department of Physiology and Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Angela A Connelly
- Department of Physiology, The University of Melbourne, Melbourne, Australia
| | - Stuart J McDougall
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Willian S Korim
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Sarah-Jane Guild
- Department of Physiology and Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Svetlana Mastitskaya
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Phuong Le
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Anja G Teschemacher
- Physiology, Neuroscience and Pharmacology, University of Bristol, Bristol, UK
| | - Sergey Kasparov
- Physiology, Neuroscience and Pharmacology, University of Bristol, Bristol, UK; Baltic Federal University, Kaliningrad, Russian Federation
| | - Gareth L Ackland
- Translational Medicine and Therapeutics, William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Simon C Malpas
- Department of Physiology and Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Robin M McAllen
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Andrew M Allen
- Department of Physiology, The University of Melbourne, Melbourne, Australia
| | - Clive N May
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia.
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
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3
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The Role of Dorsal Raphe Serotonin Neurons in the Balance between Reward and Aversion. Int J Mol Sci 2020; 21:ijms21062160. [PMID: 32245184 PMCID: PMC7139834 DOI: 10.3390/ijms21062160] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/19/2020] [Accepted: 03/19/2020] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Reward processing is fundamental for animals to survive and reproduce. Many studies have shown the importance of dorsal raphe nucleus (DRN) serotonin (5-HT) neurons in this process, but the strongly correlative link between the activity of DRN 5-HT neurons and rewarding/aversive potency is under debate. Our primary objective was to reveal this link using two different strategies to transduce DRN 5-HT neurons. METHODS For transduction of 5-HT neurons in wildtype mice, adeno-associated virus (AAV) bearing the mouse tryptophan hydroxylase 2 (TPH2) gene promoter was used. For transduction in Tph2-tTA transgenic mice, AAVs bearing the tTA-dependent TetO enhancer were used. To manipulate the activity of 5-HT neurons, optogenetic actuators (CheRiff, eArchT) were expressed by AAVs. For measurement of rewarding/aversive potency, we performed a nose-poke self-stimulation test and conditioned place preference (CPP) test. RESULTS We found that stimulation of DRN 5-HT neurons and their projections to the ventral tegmental area (VTA) increased the number of nose-pokes in self-stimulation test and CPP scores in both targeting methods. Concomitantly, CPP scores were decreased by inhibition of DRN 5-HT neurons and their projections to VTA. CONCLUSION Our findings indicate that the activity of DRN 5-HT neurons projecting to the VTA is a key modulator of balance between reward and aversion.
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Nagai Y, Nishitani N, Yasuda M, Ueda Y, Fukui Y, Andoh C, Shirakawa H, Nakagawa T, Inoue KI, Nagayasu K, Kasparov S, Nakamura K, Kaneko S. Identification of neuron-type specific promoters in monkey genome and their functional validation in mice. Biochem Biophys Res Commun 2019; 518:619-624. [PMID: 31451217 DOI: 10.1016/j.bbrc.2019.08.101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 08/18/2019] [Indexed: 12/19/2022]
Abstract
Viral gene delivery is one of the most versatile techniques for elucidating the mechanisms underlying brain dysfunction, such as neuropsychiatric disorders. Due to the complexity of the brain, expression of genetic tools, such as channelrhodopsin and calcium sensors, often has to be restricted to a specified cell type within a circuit implicated in these disorders. Only a handful of promoters targeting neuronal subtypes are currently used for viral gene delivery. Here, we isolated conserved promoter regions of several subtype-specific genes from the macaque genome and investigated their functionality in the mouse brain when used within lentiviral vectors (LVVs). Immunohistochemical analysis revealed that transgene expression induced by the promoter sequences for somatostatin (SST), cholecystokinin (CCK), parvalbumin (PV), serotonin transporter (SERT), vesicular acetylcholine transporter (vAChT), substance P (SP) and proenkephalin (PENK) was largely colocalized with specific markers for the targeted neuronal populations. Moreover, by combining these results with in silico predictions of transcription factor binding to the isolated sequences, we identified transcription factors possibly underlying cell-type specificity. These findings lay a foundation for the expansion of the current toolbox of promoters suitable for elucidating these neuronal phenotypes.
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Affiliation(s)
- Yuma Nagai
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Naoya Nishitani
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan; Department of Neuropharmacology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15 W7 Kita-ku, Sapporo, 060-8638, Japan
| | - Masaharu Yasuda
- Department of Physiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata-city, Osaka, 573-1010, Japan
| | - Yasumasa Ueda
- Department of Physiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata-city, Osaka, 573-1010, Japan
| | - Yuto Fukui
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Chihiro Andoh
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Hisashi Shirakawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Takayuki Nakagawa
- Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Ken-Ichi Inoue
- Systems Neuroscience Section, Department of Neuroscience, Primate Research Institute, Kyoto University, Inuyama, Aichi, 484-8506, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, 332-0012, Japan
| | - Kazuki Nagayasu
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Sergey Kasparov
- School of Physiology Pharmacology and Neuroscience, University of Bristol, Bristol, UK; Institute of Living Systems, Immanuel Kant Baltic Federal University, Universitetskaya str, 2, Kaliningrad, 236041, Russia
| | - Kae Nakamura
- Department of Physiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata-city, Osaka, 573-1010, Japan
| | - Shuji Kaneko
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
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5
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Nishitani N, Nagayasu K, Asaoka N, Yamashiro M, Andoh C, Nagai Y, Kinoshita H, Kawai H, Shibui N, Liu B, Hewinson J, Shirakawa H, Nakagawa T, Hashimoto H, Kasparov S, Kaneko S. Manipulation of dorsal raphe serotonergic neurons modulates active coping to inescapable stress and anxiety-related behaviors in mice and rats. Neuropsychopharmacology 2019; 44:721-732. [PMID: 30377380 PMCID: PMC6372597 DOI: 10.1038/s41386-018-0254-y] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 10/16/2018] [Accepted: 10/21/2018] [Indexed: 01/21/2023]
Abstract
Major depression and anxiety disorders are a social and economic burden worldwide. Serotonergic signaling has been implicated in the pathophysiology of these disorders and thus has been a crucial target for pharmacotherapy. However, the precise mechanisms underlying these disorders are still unclear. Here, we used species-optimized lentiviral vectors that were capable of efficient and specific transduction of serotonergic neurons in mice and rats for elucidation of serotonergic roles in anxiety-like behaviors and active coping behavior in both species. Immunohistochemical analyses revealed that lentiviral vectors with an upstream sequence of tryptophan hydroxylase 2 gene efficiently transduced serotonergic neurons with a specificity of approximately 95% in both mice and rats. Electrophysiological recordings showed that these lentiviral vectors induced sufficient expression of optogenetic tools for precise control of serotonergic neurons. Using these vectors, we demonstrate that acute activation of serotonergic neurons in the dorsal raphe nucleus increases active coping with inescapable stress in rats and mice in a time-locked manner, and that acute inhibition of these neurons increases anxiety-like behaviors specifically in rats. These findings further our understanding of the pathophysiological role of dorsal raphe serotonergic neurons in different species and the role of these neurons as therapeutic targets in major depression and anxiety disorders.
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Affiliation(s)
- Naoya Nishitani
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Kazuki Nagayasu
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
- Drug Innovation Center, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan.
- Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Yoshidahommachi, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Nozomi Asaoka
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Mayumi Yamashiro
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Chihiro Andoh
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Yuma Nagai
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Haruko Kinoshita
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Hiroyuki Kawai
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Norihiro Shibui
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Beihui Liu
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - James Hewinson
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - Hisashi Shirakawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Takayuki Nakagawa
- Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Hitoshi Hashimoto
- Drug Innovation Center, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
- Molecular Research Center for Children's Mental Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Sergey Kasparov
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK.
| | - Shuji Kaneko
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
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Wan OW, Shin E, Mattsson B, Caudal D, Svenningsson P, Björklund A. α-Synuclein induced toxicity in brain stem serotonin neurons mediated by an AAV vector driven by the tryptophan hydroxylase promoter. Sci Rep 2016; 6:26285. [PMID: 27211987 PMCID: PMC4876322 DOI: 10.1038/srep26285] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 04/27/2016] [Indexed: 02/01/2023] Open
Abstract
We studied the impact of α-synuclein overexpression in brainstem serotonin neurons using a novel vector construct where the expression of human wildtype α-synuclein is driven by the tryptophan hydroxylase promoter, allowing expression of α-synuclein at elevated levels, and with high selectivity, in serotonergic neurons. α-Synuclein induced degenerative changes in axons and dendrites, displaying a distorted appearance, suggesting accumulation and aggregation of α-synuclein as a result of impaired axonal transport, accompanied by a 40% loss of terminals, as assessed in the hippocampus. Tissue levels of serotonin and its major metabolite 5-HIAA remained largely unaltered, and the performance of the α-synuclein overexpressing rats in tests of spatial learning (water maze), anxiety related behavior (elevated plus maze) and depressive-like behavior (forced swim test) was not different from control, suggesting that the impact of the developing axonal pathology on serotonin neurotransmission was relatively mild. Overexpression of α-synuclein in the raphe nuclei, combined with overexpression in basal forebrain cholinergic neurons, resulted in more pronounced axonal pathology and significant impairment in the elevated plus maze. We conclude that α-synuclein pathology in serotonergic or cholinergic neurons alone is not sufficient to impair non-motor behaviors, but that it is their simultaneous involvement that determines severity of such symptoms.
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Affiliation(s)
- Oi Wan Wan
- Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, BMC A11, Lund 22184, Sweden
| | - Eunju Shin
- Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, BMC A11, Lund 22184, Sweden
| | - Bengt Mattsson
- Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, BMC A11, Lund 22184, Sweden
| | - Dorian Caudal
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institute, Stockholm 17176, Sweden
| | - Per Svenningsson
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institute, Stockholm 17176, Sweden
| | - Anders Björklund
- Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, BMC A11, Lund 22184, Sweden
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Mantoan Ritter L, Macdonald DC, Ritter G, Escors D, Chiara F, Cariboni A, Schorge S, Kullmann DM, Collins M. Lentiviral expression of GAD67 and CCK promoter-driven opsins to target interneuronsin vitroandin vivo. J Gene Med 2016; 18:27-37. [DOI: 10.1002/jgm.2873] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 01/18/2016] [Accepted: 01/21/2016] [Indexed: 01/19/2023] Open
Affiliation(s)
- Laura Mantoan Ritter
- Department of Clinical and Experimental Epilepsy, Institute of Neurology; University College London; London UK
- Clinical Neurosciences Department; King's College NHS Foundation Trust; Denmark Hill London UK
| | - Douglas C. Macdonald
- Division of Infection and Immunity, Paul O'Gorman Building; University College London; London UK
| | - Georg Ritter
- Science and Technology Research Institute; University of Hertfordshire; Hatfield UK
| | - David Escors
- Division of Infection and Immunity, Rayne Building; University College London; London UK
- Department of Immunomodulation; Navarrabiomed; Pamplona, Navarra Spain
| | - Francesca Chiara
- Department of Cell and Developmental Biology, Anatomy Building; University College London; London UK
| | - Anna Cariboni
- Department of Cell and Developmental Biology, Anatomy Building; University College London; London UK
- Department of Pharmacological and Biomolecular Sciences; Univeristy of Milan; Milan Italy
| | - Stephanie Schorge
- Department of Clinical and Experimental Epilepsy, Institute of Neurology; University College London; London UK
| | - Dimitri M. Kullmann
- Department of Clinical and Experimental Epilepsy, Institute of Neurology; University College London; London UK
| | - Mary Collins
- Division of Infection and Immunity, Paul O'Gorman Building; University College London; London UK
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8
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Hainer C, Mosienko V, Koutsikou S, Crook JJ, Gloss B, Kasparov S, Lumb BM, Alenina N. Beyond Gene Inactivation: Evolution of Tools for Analysis of Serotonergic Circuitry. ACS Chem Neurosci 2015; 6:1116-29. [PMID: 26132472 DOI: 10.1021/acschemneuro.5b00045] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In the brain, serotonin (5-hydroxytryptamine, 5-HT) controls a multitude of physiological and behavioral functions. Serotonergic neurons in the raphe nuclei give rise to a complex and extensive network of axonal projections throughout the whole brain. A major challenge in the analysis of these circuits is to understand how the serotonergic networks are linked to the numerous functions of this neurotransmitter. In the past, many studies employed approaches to inactivate different genes involved in serotonergic neuron formation, 5-HT transmission, or 5-HT metabolism. Although these approaches have contributed significantly to our understanding of serotonergic circuits, they usually result in life-long gene inactivation. As a consequence, compensatory changes in serotonergic and other neurotransmitter systems may occur and complicate the interpretation of the observed phenotypes. To dissect the complexity of the serotonergic system with greater precision, approaches to reversibly manipulate subpopulations of serotonergic neurons are required. In this review, we summarize findings on genetic animal models that enable control of 5-HT neuronal activity or mapping of the serotonergic system. This includes a comparative analysis of several mouse and rat lines expressing Cre or Flp recombinases under Tph2, Sert, or Pet1 promoters with a focus on specificity and recombination efficiency. We further introduce applications for Cre-mediated cell-type specific gene expression to optimize spatial and temporal precision for the manipulation of serotonergic neurons. Finally, we discuss other temporally regulated systems, such as optogenetics and designer receptors exclusively activated by designer drugs (DREADD) approaches to control 5-HT neuron activity.
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Affiliation(s)
- Cornelia Hainer
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin 13125, Germany
| | | | | | | | - Bernd Gloss
- National Institute of Environmental Health Science, Durham, North Carolina 27709, United States
| | | | | | - Natalia Alenina
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin 13125, Germany
- Institute
of Translational Biomedicine, St. Petersburg State University, St. Petersburg 199034, Russia
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9
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Parr-Brownlie LC, Bosch-Bouju C, Schoderboeck L, Sizemore RJ, Abraham WC, Hughes SM. Lentiviral vectors as tools to understand central nervous system biology in mammalian model organisms. Front Mol Neurosci 2015; 8:14. [PMID: 26041987 PMCID: PMC4434958 DOI: 10.3389/fnmol.2015.00014] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 04/30/2015] [Indexed: 01/18/2023] Open
Abstract
Lentiviruses have been extensively used as gene delivery vectors since the mid-1990s. Usually derived from the human immunodeficiency virus genome, they mediate efficient gene transfer to non-dividing cells, including neurons and glia in the adult mammalian brain. In addition, integration of the recombinant lentiviral construct into the host genome provides permanent expression, including the progeny of dividing neural precursors. In this review, we describe targeted vectors with modified envelope glycoproteins and expression of transgenes under the regulation of cell-selective and inducible promoters. This technology has broad utility to address fundamental questions in neuroscience and we outline how this has been used in rodents and primates. Combining viral tract tracing with immunohistochemistry and confocal or electron microscopy, lentiviral vectors provide a tool to selectively label and trace specific neuronal populations at gross or ultrastructural levels. Additionally, new generation optogenetic technologies can be readily utilized to analyze neuronal circuit and gene functions in the mature mammalian brain. Examples of these applications, limitations of current systems and prospects for future developments to enhance neuroscience knowledge will be reviewed. Finally, we will discuss how these vectors may be translated from gene therapy trials into the clinical setting.
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Affiliation(s)
- Louise C. Parr-Brownlie
- Department of Anatomy, Brain Health Research Centre, University of OtagoDunedin, New Zealand
- Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand
| | | | - Lucia Schoderboeck
- Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand
- Department of Biochemistry, Brain Health Research Centre, University of OtagoDunedin, New Zealand
- Department of Psychology, Brain Health Research Centre, University of OtagoDunedin, New Zealand
| | - Rachel J. Sizemore
- Department of Anatomy, Brain Health Research Centre, University of OtagoDunedin, New Zealand
- Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand
| | - Wickliffe C. Abraham
- Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand
- Department of Psychology, Brain Health Research Centre, University of OtagoDunedin, New Zealand
| | - Stephanie M. Hughes
- Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand
- Department of Biochemistry, Brain Health Research Centre, University of OtagoDunedin, New Zealand
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10
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Serotonin in fear conditioning processes. Behav Brain Res 2015; 277:68-77. [DOI: 10.1016/j.bbr.2014.07.028] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/18/2014] [Accepted: 07/21/2014] [Indexed: 12/17/2022]
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11
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Figueiredo M, Lane S, Stout RF, Liu B, Parpura V, Teschemacher AG, Kasparov S. Comparative analysis of optogenetic actuators in cultured astrocytes. Cell Calcium 2014; 56:208-14. [PMID: 25109549 PMCID: PMC4169180 DOI: 10.1016/j.ceca.2014.07.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 07/15/2014] [Indexed: 11/30/2022]
Abstract
We compared six optogenetic tools to selectively stimulate and study astrocytes. Channelrhodopsin-2 variants cause release of Ca2+ from intracellular stores. Opto-GPCRs activate selective second messenger cascades, leading to [Ca2+]i rises. Autocrine action of ATP mediates the bulk of [Ca2+]i signals evoked by opto-GPCRs. Current optogenetic tools initiate relevant signalling events in astrocytes.
Astrocytes modulate synaptic transmission via release of gliotransmitters such as ATP, glutamate, d-serine and l-lactate. One of the main problems when studying the role of astrocytes in vitro and in vivo is the lack of suitable tools for their selective activation. Optogenetic actuators can be used to manipulate astrocytic activity by expression of variants of channelrhodopsin-2 (ChR2) or other optogenetic actuators with the aim to initiate intracellular events such as intracellular Ca2+ ([Ca2+]i) and/or cAMP increases. We have developed an array of adenoviral vectors (AVV) with ChR2-like actuators, including an enhanced ChR2 mutant (H134R), and a mutant with improved Ca2+ permeability (Ca2+ translocating channelrhodopsin, CatCh). We show here that [Ca2+]i elevations evoked by ChR2(H134R) and CatCh in astrocytes are largely due to release of Ca2+ from the intracellular stores. The autocrine action of ATP which is released under these conditions and acts on the P2Y receptors also contributes to the [Ca2+]i elevations. We also studied effects evoked using light-sensitive G-protein coupled receptors (opto-adrenoceptors). Activation of optoα1AR (Gq-coupled) and optoβ2AR (Gs-coupled) resulted in astrocytic [Ca2+]i increases which were suppressed by blocking the corresponding intracellular signalling cascade (phospholipase C and adenylate cyclase, respectively). Interestingly, the bulk of [Ca2+]i responses evoked using either optoAR was blocked by an ATP degrading enzyme, apyrase, or a P2Y1 receptor blocker, MRS 2179, indicating that they are to a large extent triggered by the autocrine action of ATP. We conclude that, whilst optimal tools for control of astrocytes are yet to be generated, the currently available optogenetic actuators successfully initiate biologically relevant signalling events in astrocytes.
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Affiliation(s)
- Melina Figueiredo
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK
| | - Samantha Lane
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK
| | - Randy F Stout
- Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama, Birmingham, AL 35294, USA; The Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Beihui Liu
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK
| | - Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama, Birmingham, AL 35294, USA; Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
| | - Anja G Teschemacher
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK.
| | - Sergey Kasparov
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK.
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Hewinson J, Paton JFR, Kasparov S. Viral gene delivery: optimized protocol for production of high titer lentiviral vectors. Methods Mol Biol 2013; 998:65-75. [PMID: 23529421 DOI: 10.1007/978-1-62703-351-0_5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
HIV-derived lentiviral vectors (LVV) are among the most commonly used gene delivery vehicles. Their production in high quantities, which enables concentration of viral particles to high titers, is important for their successful application in both biomedical research and gene therapy. LVV are produced by co-transfection of three or more plasmids into a packaging cell line followed by several purification and concentration steps. Protocols currently in circulation differ from each other but the direct comparison of their efficacy based on the published information is extremely difficult because more than one variable may be changed and essential information may be omitted. We systematically evaluated three protocols and found that one single modification described here, using FuGene(®) 6 in the co-transfection step, increase LVV output almost 20 times as compared to the most commonly used calcium phosphate (CaPO4) transfection technique. Unexpectedly FuGene(®) 6 was also much more efficient than another widely used reagent, Superfect. Dependent on requirements, this permits a dramatic downscaling of the packaging stage of viral production, and/or super-concentration of LVV to achieve stronger expression. For example we were able to prepare ∼25 μL of high titer LVV suitable for injections into rodent brain using a single T75 cm(2) cell culture flask of packaging cells. The same output would require up to 20 times more packaging cells and reagents following conventional protocols. We illustrate the potential of our approach using transfection of primary neuronal cultures with LVV expressing an optogenetic actuator channelrhodopsin-2. Our observations should help to achieve reproducible production of high titer LVV for experimental and potential therapeutic applications.
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Affiliation(s)
- James Hewinson
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
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13
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Gerits A, Vanduffel W. Optogenetics in primates: a shining future? Trends Genet 2013; 29:403-11. [DOI: 10.1016/j.tig.2013.03.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 02/28/2013] [Accepted: 03/26/2013] [Indexed: 11/28/2022]
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Gentile MT, Nawa Y, Lunardi G, Florio T, Matsui H, Colucci-D'Amato L. Tryptophan hydroxylase 2 (TPH2) in a neuronal cell line: modulation by cell differentiation and NRSF/rest activity. J Neurochem 2012; 123:963-70. [PMID: 22958208 DOI: 10.1111/jnc.12004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 08/29/2012] [Accepted: 09/01/2012] [Indexed: 01/16/2023]
Abstract
Serotonin (5-HT) is a neurotransmitter involved in many aspects of the neuronal function. The synthesis of 5-HT is initiated by the hydroxylation of tryptophan, catalyzed by tryptophan hydroxylase (TPH). Two isoforms of TPH (TPH1 and TPH2) have been identified, with TPH2 almost exclusively expressed in the brain. Following TPH2 discovery, it was reported that polymorphisms of both gene and non-coding regions are associated with a spectrum of psychiatric disorders. Thus, insights into the mechanisms that specifically regulate TPH2 expression and its modulation by exogenous stimuli may represent a new therapeutic approach to modify serotonergic neurotransmission. To this aim, a CNS-originated cell line expressing TPH2 endogenously represents a valid model system. In this study, we report that TPH2 transcript and protein are modulated by neuronal differentiation in the cell line A1 mes-c-myc (A1). Moreover, we show luciferase activity driven by the human TPH2 promoter region and demonstrate that upon mutation of the NRSF/REST responsive element, the promoter activity strongly increases with cell differentiation. Our data suggest that A1 cells could represent a model system, allowing an insight into the mechanisms of regulation of TPH2 and to identify novel therapeutic targets in the development of drugs for the management of psychiatric disorders.
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Affiliation(s)
- Maria Teresa Gentile
- Department of Environmental, Biological and Pharmaceutical Sciences and Technology, Second University of Naples, Caserta, Italy
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15
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Mastitskaya S, Marina N, Gourine A, Gilbey MP, Spyer KM, Teschemacher AG, Kasparov S, Trapp S, Ackland GL, Gourine AV. Cardioprotection evoked by remote ischaemic preconditioning is critically dependent on the activity of vagal pre-ganglionic neurones. Cardiovasc Res 2012; 95:487-94. [PMID: 22739118 PMCID: PMC3422080 DOI: 10.1093/cvr/cvs212] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Aims Innate mechanisms of inter-organ protection underlie the phenomenon of remote ischaemic preconditioning (RPc) in which episode(s) of ischaemia and reperfusion in tissues remote from the heart reduce myocardial ischaemia/reperfusion injury. The uncertainty surrounding the mechanism(s) underlying RPc centres on whether humoral factor(s) produced during ischaemia/reperfusion of remote tissue and released into the systemic circulation mediate RPc, or whether a neural signal is required. While these two hypotheses may not be incompatible, one approach to clarify the potential role of a neural pathway requires targeted disruption or activation of discrete central nervous substrate(s). Methods and results Using a rat model of myocardial ischaemia/reperfusion injury in combination with viral gene transfer, pharmaco-, and optogenetics, we tested the hypothesis that RPc cardioprotection depends on the activity of vagal pre-ganglionic neurones and consequently an intact parasympathetic drive. For cell-specific silencing or activation, neurones of the brainstem dorsal motor nucleus of the vagus nerve (DVMN) were targeted using viral vectors to express a Drosophila allatostatin receptor (AlstR) or light-sensitive fast channelrhodopsin variant (ChIEF), respectively. RPc cardioprotection, elicited by ischaemia/reperfusion of the limbs, was abolished when DVMN neurones transduced to express AlstR were silenced by selective ligand allatostatin or in conditions of systemic muscarinic receptor blockade with atropine. In the absence of remote ischaemia/reperfusion, optogenetic activation of DVMN neurones transduced to express ChIEF reduced infarct size, mimicking the effect of RPc. Conclusion These data indicate a crucial dependence of RPc cardioprotection against ischaemia/reperfusion injury upon the activity of a distinct population of vagal pre-ganglionic neurones.
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Affiliation(s)
- Svetlana Mastitskaya
- Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
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16
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An optogenetic approach in epilepsy. Neuropharmacology 2012; 69:89-95. [PMID: 22698957 DOI: 10.1016/j.neuropharm.2012.05.049] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 05/28/2012] [Accepted: 05/29/2012] [Indexed: 12/14/2022]
Abstract
Optogenetic tools comprise a variety of different light-sensitive proteins from single-cell organisms that can be expressed in mammalian neurons and effectively control their excitability. Two main classes of optogenetic tools allow to either depolarize or hyperpolarize, and respectively generate or inhibit action potentials in selective populations of neurons. This opens unprecedented possibilities for delineating the role of certain neuronal populations in brain processing and diseases. Moreover, optogenetics may be considered for developing potential treatment strategies for brain diseases, particularly for excitability disorders such as epilepsy. Expression of the inhibitory halorhodopsin NpHR in hippocampal principal cells has been recently used as a tool to effectively control chemically and electrically induced epileptiform activity in slice preparations, and to reduce in vivo spiking induced by tetanus toxin injection in the motor cortex. In this review we give a comprehensive summary of what has been achieved so far in the field of epilepsy using optogenetics, and discuss some of the possible strategies that could be envisaged in the future. We also point out some of the challenges and pitfalls in relation to possible outcomes of using optogenetics for controlling network excitability, and associated brain diseases. This article is part of the Special Issue entitled 'New Targets and Approaches to the Treatment of Epilepsy'.
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Manfredsson FP, Bloom DC, Mandel RJ. Regulated protein expression for in vivo gene therapy for neurological disorders: progress, strategies, and issues. Neurobiol Dis 2012; 48:212-21. [PMID: 22426391 DOI: 10.1016/j.nbd.2012.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 01/28/2012] [Accepted: 03/01/2012] [Indexed: 01/16/2023] Open
Abstract
The field of in vivo gene therapy has matured to the point where there are numerous clinical trials underway including late-stage clinical trials. Several viral vectors are especially efficient and support lifetime protein expression in the brain and a number of clinical trials are underway for various progressive or chronic neurological disorders including Parkinson's disease, Alzheimer's disease, and Batten's disease. To date, however, none of the vectors in clinical use have any direct way to reverse or control their transgene product in the event continued protein expression should become problematic. Several schemes that use elements within the vector design have been developed that allow an external drug or pro-drug to alter ongoing protein expression after in vivo gene transfer. The most promising and most studied regulated protein expression methods for in vivo gene transfer are reviewed. In addition, potential scientific and clinical advantages of transgene regulation for gene therapy are discussed.
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Affiliation(s)
- Fredric P Manfredsson
- Department of Translational Science & Molecular Medicine, Van Andel Institute, Michigan State University, 333 Bostwick Ave NE, Grand Rapids, MI 49503, USA
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Abstract
Both observational and perturbational technologies are essential for advancing the understanding of brain function and dysfunction. But while observational techniques have greatly advanced in the last century, techniques for perturbation that are matched to the speed and heterogeneity of neural systems have lagged behind. The technology of optogenetics represents a step toward addressing this disparity. Reliable and targetable single-component tools (which encompass both light sensation and effector function within a single protein) have enabled versatile new classes of investigation in the study of neural systems. Here we provide a primer on the application of optogenetics in neuroscience, focusing on the single-component tools and highlighting important problems, challenges, and technical considerations.
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Affiliation(s)
- Ofer Yizhar
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
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19
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Huh Y, Oh MS, Leblanc P, Kim KS. Gene transfer in the nervous system and implications for transsynaptic neuronal tracing. Expert Opin Biol Ther 2010; 10:763-72. [PMID: 20367126 DOI: 10.1517/14712591003796538] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
IMPORTANCE OF THE FIELD Neuronal circuitries are determined by specific synaptic connections and they provide the cellular basis of cognitive processes and behavioral functions. To investigate neuronal circuitries, tracers are typically used to identify the original neurons and their projection targets. AREAS COVERED IN THIS REVIEW Traditional tracing methods using chemical tracers have major limitations such as non-specificity. In this review, we highlight novel genetic tracing approaches that enable visualization of specific neuronal pathways by introducing cDNA encoding a transsynaptic tracer. In contrast to conventional tracing methods, these genetic approaches use cell-type-specific promoters to express transsynaptic tracers such as wheat germ agglutinin and C-terminal fragment of tetanus toxin, which allows labeling of either the input or output populations and connections of specific neuronal type. WHAT THE READER WILL GAIN Specific neuronal circuit information by these genetic approaches will allow more precise, comprehensive and novel information about individual neural circuits and their function in normal and diseased brains. TAKE HOME MESSAGE Using tracer gene transfer, neuronal circuit plasticity after traumatic injury or neurodegenerative diseases can be visualized. Also, this can provide a good marker for evaluation of therapeutic effects of neuroprotective or neurotrophic agents.
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Affiliation(s)
- Youngbuhm Huh
- Department of Anatomy and Neurobiology, Kyung Hee University, Seoul, Republic of Korea
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20
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Serotonin: a regulator of neuronal morphology and circuitry. Trends Neurosci 2010; 33:424-34. [PMID: 20561690 DOI: 10.1016/j.tins.2010.05.005] [Citation(s) in RCA: 213] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 05/17/2010] [Accepted: 05/18/2010] [Indexed: 11/22/2022]
Abstract
Serotonin is an important neuromodulator associated with a wide range of physiological effects in the central nervous system. The exact mechanisms whereby serotonin influences brain development are not well understood, although studies in invertebrate and vertebrate model organisms are beginning to unravel a regulatory role for serotonin in neuronal morphology and circuit formation. Recent data suggest a developmental window during which altered serotonin levels permanently influence neuronal circuitry, however, the temporal constraints and molecular mechanisms responsible are still under investigation. Growing evidence suggests that alterations in early serotonin signaling contribute to a number of neurodevelopmental and neuropsychiatric disorders. Thus, understanding how altered serotonin signaling affects neuronal morphology and plasticity, and ultimately animal physiology and pathophysiology, will be of great significance.
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Kasparov S, Teschemacher AG. The use of viral gene transfer in studies of brainstem noradrenergic and serotonergic neurons. Philos Trans R Soc Lond B Biol Sci 2009; 364:2565-76. [PMID: 19651657 DOI: 10.1098/rstb.2009.0073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In contrast to some other neuronal populations, for example hippocampal or cortical pyramidal neurons, mechanisms of synaptic integration and transmitter release in central neurons that contain noradrenaline (NA) and serotonin (5HT) are not well understood. These cells, crucial for a wide range of autonomic and behavioural processes, have long un-myelinated axons with hundreds of varicosities where transmitters are synthesized and released. Both seem to signal mostly in 'volume transmission' mode. Very little is known about the rules that apply to this type of transmission in the brain and the factors that regulate the release of NA and 5HT. We discuss some of our published studies and more recent experiments in which viral vectors were used to investigate the physiology of these neuronal populations. We also focus on currently unresolved issues concerning the mechanism of volume transmission by NA and 5HT in the brain. We suggest that clarifying the role of astroglia in this process could be essential for our understanding of central noradrenergic and 5HT signalling.
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Affiliation(s)
- S Kasparov
- Department of Physiology and Pharmacology, Bristol Heart Institute, School of Medical Sciences, University of Bristol, , Bristol BS8 1TD, UK.
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Papale A, Cerovic M, Brambilla R. Viral vector approaches to modify gene expression in the brain. J Neurosci Methods 2009; 185:1-14. [PMID: 19699233 DOI: 10.1016/j.jneumeth.2009.08.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 08/13/2009] [Accepted: 08/14/2009] [Indexed: 12/31/2022]
Abstract
The use of viral vectors as gene transfer tools for the central nervous system has seen a significant growth in the last decade. Improvements in the safety, efficiency and specificity of vectors for clinical applications have proven to be beneficial also for basic neuroscience research. This review will discuss the viral systems currently available to neuroscientists and some of the recent achievements in the study of synaptic function, memory and drug addiction.
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Affiliation(s)
- Alessandro Papale
- Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Foundation and University, Milano, Italy
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Benzekhroufa K, Liu B, Tang F, Teschemacher AG, Kasparov S. Adenoviral vectors for highly selective gene expression in central serotonergic neurons reveal quantal characteristics of serotonin release in the rat brain. BMC Biotechnol 2009; 9:23. [PMID: 19298646 PMCID: PMC2672940 DOI: 10.1186/1472-6750-9-23] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Accepted: 03/19/2009] [Indexed: 11/17/2022] Open
Abstract
Background 5-hydroxytryptamine (5 HT, serotonin) is one of the key neuromodulators in mammalian brain, but many fundamental properties of serotonergic neurones and 5 HT release remain unknown. The objective of this study was to generate an adenoviral vector system for selective targeting of serotonergic neurones and apply it to study quantal characteristics of 5 HT release in the rat brain. Results We have generated adenoviral vectors which incorporate a 3.6 kb fragment of the rat tryptophan hydroxylase-2 (TPH-2) gene which selectively (97% co-localisation with TPH-2) target raphe serotonergic neurones. In order to enhance the level of expression a two-step transcriptional amplification strategy was employed. This allowed direct visualization of serotonergic neurones by EGFP fluorescence. Using these vectors we have performed initial characterization of EGFP-expressing serotonergic neurones in rat organotypic brain slice cultures. Fluorescent serotonergic neurones were identified and studied using patch clamp and confocal Ca2+ imaging and had features consistent with those previously reported using post-hoc identification approaches. Fine processes of serotonergic neurones could also be visualized in un-fixed tissue and morphometric analysis suggested two putative types of axonal varicosities. We used micro-amperometry to analyse the quantal characteristics of 5 HT release and found that central 5 HT exocytosis occurs predominantly in quanta of ~28000 molecules from varicosities and ~34000 molecules from cell bodies. In addition, in somata, we observed a minority of large release events discharging on average ~800000 molecules. Conclusion For the first time quantal release of 5 HT from somato-dendritic compartments and axonal varicosities in mammalian brain has been demonstrated directly and characterised. Release from somato-dendritic and axonal compartments might have different physiological functions. Novel vectors generated in this study open a host of new experimental opportunities and will greatly facilitate further studies of the central serotonergic system.
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Affiliation(s)
- Kheira Benzekhroufa
- Department of Physiology and Pharmacology, University of Bristol, BS8 1TD, UK.
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