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Li J, Liu T, Dong Y, Kondoh K, Lu Z. Trans-synaptic Neural Circuit-Tracing with Neurotropic Viruses. Neurosci Bull 2019; 35:909-920. [PMID: 31004271 PMCID: PMC6754522 DOI: 10.1007/s12264-019-00374-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 12/15/2018] [Indexed: 12/19/2022] Open
Abstract
A central objective in deciphering the nervous system in health and disease is to define the connections of neurons. The propensity of neurotropic viruses to spread among synaptically-linked neurons makes them ideal for mapping neural circuits. So far, several classes of viral neuronal tracers have become available and provide a powerful toolbox for delineating neural networks. In this paper, we review the recent developments of neurotropic viral tracers and highlight their unique properties in revealing patterns of neuronal connections.
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Affiliation(s)
- Jiamin Li
- Guangdong Provincial Key Laboratory of Brain Connectome and Behavior, The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Taian Liu
- Guangdong Provincial Key Laboratory of Brain Connectome and Behavior, The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Yun Dong
- Guangdong Provincial Key Laboratory of Brain Connectome and Behavior, The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Kunio Kondoh
- Division of Endocrinology and Metabolism, Department of Homeostatic Regulation, National Institute for Physiological Sciences, National Institute of Natural Sciences, Myodaiji, Okazaki, Aichi, 444-8585, Japan.
- Japan Science and Technology Agency, PRESTO, Myodaiji, Okazaki, Aichi, 444-8585, Japan.
| | - Zhonghua Lu
- Guangdong Provincial Key Laboratory of Brain Connectome and Behavior, The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
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Sun Y, Gao Y, Tidei JJ, Shen M, Hoang JT, Wagner DF, Zhao X. Loss of MeCP2 in immature neurons leads to impaired network integration. Hum Mol Genet 2019; 28:245-257. [PMID: 30277526 DOI: 10.1093/hmg/ddy338] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 09/18/2018] [Indexed: 12/12/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations or deletions in Methyl-CpG-binding Protein 2 (MeCP2), a brain-enriched transcriptional regulator. MeCP2 is highly expressed during neuronal maturation and its deficiency results in impaired dendritic morphogenesis and reduced dendritic spine numbers in developing neurons. However, whether MeCP2 deficiency impacts the integration of new neurons has not been directly assessed. In this study, we developed a modified rabies virus-mediated monosynaptic retrograde tracing method to interrogate presynaptic integration of MeCP2-deficient new neurons born in the adult hippocampus, a region with lifelong neurogenesis and plasticity. We found that selective deletion of MeCP2 in adult-born new neurons impaired their long-range connectivity to the cortex, whereas their connectivity within the local hippocampal circuits or with subcortical regions was not significantly affected. We further showed that knockdown of MeCP2 in primary hippocampal neurons also resulted in reduced network integration. Interestingly, (1-3) insulin-like growth factor-1 (IGF-1), a small peptide under clinical trial testing for RTT, rescued neuronal integration deficits of MeCP2-deficient neurons in vitro but not in vivo. In addition, (1-3) IGF-1 treatment corrected aberrant excitability and network synchrony of MeCP2-deficient hippocampal neurons. Our results indicate that MeCP2 is essential for immature neurons to establish appropriate network connectivity.
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Affiliation(s)
- Yi Sun
- National Key Research Laboratory of Natural and Biomimetic Drugs.,Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University, Beijing, PR China.,Waisman Center
| | - Yu Gao
- Waisman Center.,Department of Neuroscience
| | | | | | | | | | - Xinyu Zhao
- Waisman Center.,Department of Neuroscience.,Cellular and Molecular Biology Program, University of Wisconsin-Madison, Madison, WI, USA
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Kwan V, Meka D, White S, Hung C, Holzapfel N, Walker S, Murtaza N, Unda B, Schwanke B, Yuen R, Habing K, Milsom C, Hope K, Truant R, Scherer S, Calderon de Anda F, Singh K. DIXDC1 Phosphorylation and Control of Dendritic Morphology Are Impaired by Rare Genetic Variants. Cell Rep 2016; 17:1892-1904. [DOI: 10.1016/j.celrep.2016.10.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 09/02/2016] [Accepted: 10/14/2016] [Indexed: 10/20/2022] Open
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Ghanem A, Conzelmann KK. G gene-deficient single-round rabies viruses for neuronal circuit analysis. Virus Res 2016; 216:41-54. [DOI: 10.1016/j.virusres.2015.05.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 05/28/2015] [Accepted: 05/31/2015] [Indexed: 12/11/2022]
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Adult Hippocampal Neurogenesis, Fear Generalization, and Stress. Neuropsychopharmacology 2016; 41:24-44. [PMID: 26068726 PMCID: PMC4677119 DOI: 10.1038/npp.2015.167] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/29/2015] [Accepted: 06/05/2015] [Indexed: 12/21/2022]
Abstract
The generalization of fear is an adaptive, behavioral, and physiological response to the likelihood of threat in the environment. In contrast, the overgeneralization of fear, a cardinal feature of posttraumatic stress disorder (PTSD), manifests as inappropriate, uncontrollable expression of fear in neutral and safe environments. Overgeneralization of fear stems from impaired discrimination of safe from aversive environments or discernment of unlikely threats from those that are highly probable. In addition, the time-dependent erosion of episodic details of traumatic memories might contribute to their generalization. Understanding the neural mechanisms underlying the overgeneralization of fear will guide development of novel therapeutic strategies to combat PTSD. Here, we conceptualize generalization of fear in terms of resolution of interference between similar memories. We propose a role for a fundamental encoding mechanism, pattern separation, in the dentate gyrus (DG)-CA3 circuit in resolving interference between ambiguous or uncertain threats and in preserving episodic content of remote aversive memories in hippocampal-cortical networks. We invoke cellular-, circuit-, and systems-based mechanisms by which adult-born dentate granule cells (DGCs) modulate pattern separation to influence resolution of interference and maintain precision of remote aversive memories. We discuss evidence for how these mechanisms are affected by stress, a risk factor for PTSD, to increase memory interference and decrease precision. Using this scaffold we ideate strategies to curb overgeneralization of fear in PTSD.
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Abstract
Stem cell-based therapies hold considerable promise for many currently devastating neurological disorders. Substantial progress has been made in the derivation of disease-relevant human donor cell populations. Behavioral data in relevant animal models of disease have demonstrated therapeutic efficacy for several cell-based approaches. Consequently, cGMP grade cell products are currently being developed for first in human clinical trials in select disorders. Despite the therapeutic promise, the presumed mechanism of action of donor cell populations often remains insufficiently validated. It depends greatly on the properties of the transplanted cell type and the underlying host pathology. Several new technologies have become available to probe mechanisms of action in real time and to manipulate in vivo cell function and integration to enhance therapeutic efficacy. Results from such studies generate crucial insight into the nature of brain repair that can be achieved today and push the boundaries of what may be possible in the future.
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Finkbeiner S, Frumkin M, Kassner PD. Cell-based screening: extracting meaning from complex data. Neuron 2015; 86:160-74. [PMID: 25856492 PMCID: PMC4457442 DOI: 10.1016/j.neuron.2015.02.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 09/23/2014] [Accepted: 01/22/2015] [Indexed: 01/23/2023]
Abstract
Unbiased discovery approaches have the potential to uncover neurobiological insights into CNS disease and lead to the development of therapies. Here, we review lessons learned from imaging-based screening approaches and recent advances in these areas, including powerful new computational tools to synthesize complex data into more useful knowledge that can reliably guide future research and development.
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Affiliation(s)
- Steven Finkbeiner
- Director of the Taube/Koret Center for Neurodegenerative Disease and the Hellman Family Foundation Program in Alzheimer's Disease Research, Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Departments of Neurology and Physiology, University of California, San Francisco, San Francisco, CA 94143, USA.
| | - Michael Frumkin
- Director of Engineering, Research, Google, Inc., 1600 Amphitheatre Parkway, Mountain View, CA 94043, USA
| | - Paul D Kassner
- Director of Research, Amgen, Inc., 1120 Veterans Boulevard South, San Francisco, CA 94080, USA
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Wang D, He X, Zhao Z, Feng Q, Lin R, Sun Y, Ding T, Xu F, Luo M, Zhan C. Whole-brain mapping of the direct inputs and axonal projections of POMC and AgRP neurons. Front Neuroanat 2015; 9:40. [PMID: 25870542 PMCID: PMC4375998 DOI: 10.3389/fnana.2015.00040] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 03/12/2015] [Indexed: 01/21/2023] Open
Abstract
Pro-opiomelanocortin (POMC) neurons in the arcuate nucleus (ARC) of the hypothalamus and nucleus tractus solitarius (NTS) of the brainstem play important roles in suppressing food intake and maintaining energy homeostasis. Previous tract-tracing studies have revealed the axonal connection patterns of these two brain areas, but the intermingling of POMC neurons with other neuron types has made it challenging to precisely identify the inputs and outputs of POMC neurons. In this study, we used the modified rabies virus to map the brain areas that provide direct inputs to the POMC neurons in the ARC and NTS as well as the inputs to the ARC AgRP neurons for comparison. ARC POMC neurons receive inputs from dozens of discrete structures throughout the forebrain and brainstem. The brain areas containing the presynaptic partners of ARC POMC neurons largely overlap with those of ARC AgRP neurons, although POMC neurons receive relatively broader, denser inputs. Furthermore, POMC neurons in the NTS receive direct inputs predominantly from the brainstem and show very different innervation patterns for POMC neurons in the ARC. By selectively expressing fluorescent markers in the ARC and NTS POMC neurons, we found that almost all of their major presynaptic partners are innervated by POMC neurons in the two areas, suggesting that there are strong reciprocal projections among the major POMC neural pathways. By comprehensively chartering the whole-brain connections of the central melanocortin system in a cell-type-specific manner, this study lays the foundation for dissecting the roles and underlying circuit mechanisms of specific neural pathways in regulating energy homeostasis.
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Affiliation(s)
- Daqing Wang
- School of Life Sciences, Tsinghua University Beijing China ; National Institute of Biological Sciences Beijing, China
| | - Xiaobing He
- Key Laboratory of Magnetic Resonance in Biological Systems and State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences Wuhan, China ; University of Chinese Academy of Sciences Beijing, China
| | - Zhe Zhao
- National Institute of Biological Sciences Beijing, China
| | - Qiru Feng
- National Institute of Biological Sciences Beijing, China
| | - Rui Lin
- National Institute of Biological Sciences Beijing, China
| | - Yue Sun
- National Institute of Biological Sciences Beijing, China
| | - Ting Ding
- Key Laboratory of Magnetic Resonance in Biological Systems and State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences Wuhan, China
| | - Fuqiang Xu
- Key Laboratory of Magnetic Resonance in Biological Systems and State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences Wuhan, China ; University of Chinese Academy of Sciences Beijing, China ; Wuhan National Laboratory for Optoelectronics Wuhan, China
| | - Minmin Luo
- School of Life Sciences, Tsinghua University Beijing China ; National Institute of Biological Sciences Beijing, China
| | - Cheng Zhan
- National Institute of Biological Sciences Beijing, China
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Abstract
Rabies viruses, negative-strand RNA viruses, infect neurons through axon terminals and spread trans-synaptically in a retrograde direction between neurons. Rabies viruses whose glycoprotein (G) gene is deleted from the genome cannot spread across synapses. Complementation of G in trans, however, enables trans-synaptic spreading of G-deleted rabies viruses to directly connected, presynaptic neurons. Recombinant rabies viruses can encode genes of interest for labeling cells, controlling gene expression and monitoring or manipulating neural activity. Cre-dependent or bridge protein-mediated transduction and single-cell electroporation via the EnvA-TVA or EnvB-TVB (envelope glycoprotein and its specific receptor for avian sarcoma leukosis virus subgroup A or B) system allow cell type-specific or single cell-specific targeting. These rabies virus-based approaches permit the linking of connectivity to cell morphology and circuit function for particular cell types or single cells. Here we describe methods for construction of rabies viral vectors, recovery of G-deleted rabies viruses from cDNA, amplification of the viruses, pseudotyping them with EnvA or EnvB and concentration and titration of the viruses. The entire protocol takes 6-8 weeks.
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Garcia I, Kim C, Arenkiel BR. Revealing neuronal circuitry using stem cell-derived neurons. CURRENT PROTOCOLS IN STEM CELL BIOLOGY 2013; Chapter 2:Unit 2D.15. [PMID: 23661247 PMCID: PMC4004020 DOI: 10.1002/9780470151808.sc02d15s25] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mouse embryonic stem cell (mESC)-derived neurons are a renewable cell source for investigation of neuronal circuits. Engineering circuit-tracing components into stem cells facilitates studies on mechanisms of synaptic coupling and circuitogenesis. This unit details methods for the generation of mESC-derived neurons harboring trans-synaptic viral tracing elements, which are used for investigation of synaptic connections within circuits in vitro, ex vivo, and in vivo. The first protocol describes procedures for feeder-free passaging of mESCs, modified to carry reporter and rabies virus tracing elements. The second protocol describes in vitro generation of neurons from these ESCs. The last protocols describe the use of ESC-derived neurons as "source cells" for rabies virus circuit-tracing to identify inputs onto synaptically connected neurons. Given the broad applicability, these protocols can be applied to investigate the ability of in vitro-derived neurons to establish/maintain synaptic connections in disease models, and/or with human-induced pluripotent stem cells.
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Affiliation(s)
- Isabella Garcia
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, USA
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Garcia I, Kim C, Arenkiel BR. Genetic strategies to investigate neuronal circuit properties using stem cell-derived neurons. Front Cell Neurosci 2012; 6:59. [PMID: 23264761 PMCID: PMC3524522 DOI: 10.3389/fncel.2012.00059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 11/30/2012] [Indexed: 01/28/2023] Open
Abstract
The mammalian brain is anatomically and functionally complex, and prone to diverse forms of injury and neuropathology. Scientists have long strived to develop cell replacement therapies to repair damaged and diseased nervous tissue. However, this goal has remained unrealized for various reasons, including nascent knowledge of neuronal development, the inability to track and manipulate transplanted cells within complex neuronal networks, and host graft rejection. Recent advances in embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) technology, alongside novel genetic strategies to mark and manipulate stem cell-derived neurons, now provide unprecedented opportunities to investigate complex neuronal circuits in both healthy and diseased brains. Here, we review current technologies aimed at generating and manipulating neurons derived from ESCs and iPSCs toward investigation and manipulation of complex neuronal circuits, ultimately leading to the design and development of novel cell-based therapeutic approaches.
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Affiliation(s)
- Isabella Garcia
- Program in Developmental Biology, Baylor College of Medicine Houston, TX, USA ; Medical Scientist Training Program, Baylor College of Medicine Houston, TX, USA
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