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Wouterlood FG. Techniques to Render Dendritic Spines Visible in the Microscope. ADVANCES IN NEUROBIOLOGY 2023; 34:69-102. [PMID: 37962794 DOI: 10.1007/978-3-031-36159-3_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
A tiny detail visible on certain neurons at the limit of resolution in light microscopy went in 130 years of neuroscience research through a dazzling career from suspicious staining artifact to what we recognize today as a complex postsynaptic molecular machine: the dendritic spine.This chapter deals with techniques to make spines visible. The original technique, Golgi silver staining, is still being used today. Electron microscopy and automated field ion beam scanning electron microscopy are ultrahigh resolution techniques, albeit specialized. Other methods are intracellular injection, uptake of dyes, and recently the exploitation of genetically modified animals in which certain neurons express fluorescent protein in all their processes, including the nooks and crannies of their dendritic spines.
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Affiliation(s)
- Floris G Wouterlood
- Department of Anatomy & Neurosciences, Amsterdam UMC, Amsterdam, The Netherlands
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Lanciego JL, Wouterlood FG. Neuroanatomical tract-tracing techniques that did go viral. Brain Struct Funct 2020; 225:1193-1224. [PMID: 32062721 PMCID: PMC7271020 DOI: 10.1007/s00429-020-02041-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 01/31/2020] [Indexed: 12/29/2022]
Abstract
Neuroanatomical tracing methods remain fundamental for elucidating the complexity of brain circuits. During the past decades, the technical arsenal at our disposal has been greatly enriched, with a steady supply of fresh arrivals. This paper provides a landscape view of classical and modern tools for tract-tracing purposes. Focus is placed on methods that have gone viral, i.e., became most widespread used and fully reliable. To keep an historical perspective, we start by reviewing one-dimensional, standalone transport-tracing tools; these including today's two most favorite anterograde neuroanatomical tracers such as Phaseolus vulgaris-leucoagglutinin and biotinylated dextran amine. Next, emphasis is placed on several classical tools widely used for retrograde neuroanatomical tracing purposes, where Fluoro-Gold in our opinion represents the best example. Furthermore, it is worth noting that multi-dimensional paradigms can be designed by combining different tracers or by applying a given tracer together with detecting one or more neurochemical substances, as illustrated here with several examples. Finally, it is without any doubt that we are currently witnessing the unstoppable and spectacular rise of modern molecular-genetic techniques based on the use of modified viruses as delivery vehicles for genetic material, therefore, pushing the tract-tracing field forward into a new era. In summary, here, we aim to provide neuroscientists with the advice and background required when facing a choice on which neuroanatomical tracer-or combination thereof-might be best suited for addressing a given experimental design.
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Affiliation(s)
- Jose L Lanciego
- Neurosciences Department, Center for Applied Medical Research (CIMA), University of Navarra, Pio XII Avenue 55, 31008, Pamplona, Spain.
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CiberNed), Pamplona, Spain.
- Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.
| | - Floris G Wouterlood
- Department of Anatomy and Neurosciences, Amsterdam University Medical Centers, Location VUmc, Neuroscience Campus Amsterdam, P.O. Box 7057, 1007 MB, Amsterdam, The Netherlands.
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Hong YG, Kang B, Lee S, Lee Y, Ju BG, Jeong S. Identification of cis -Regulatory Region Controlling Semaphorin-1a Expression in the Drosophila Embryonic Nervous System. Mol Cells 2020; 43:228-235. [PMID: 32024353 PMCID: PMC7103886 DOI: 10.14348/molcells.2019.0294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/19/2019] [Accepted: 12/20/2019] [Indexed: 11/27/2022] Open
Abstract
The Drosophila transmembrane semaphorin Sema-1a mediates forward and reverse signaling that plays an essential role in motor and central nervous system (CNS) axon pathfinding during embryonic neural development. Previous immunohistochemical analysis revealed that Sema-1a is expressed on most commissural and longitudinal axons in the CNS and five motor nerve branches in the peripheral nervous system (PNS). However, Sema-1a-mediated axon guidance function contributes significantly to both intersegmental nerve b (ISNb) and segmental nerve a (SNa), and slightly to ISNd and SNc, but not to ISN motor axon pathfinding. Here, we uncover three cis-regulatory elements (CREs), R34A03, R32H10, and R33F06, that robustly drove reporter expression in a large subset of neurons in the CNS. In the transgenic lines R34A03 and R32H10 reporter expression was consistently observed on both ISNb and SNa nerve branches, whereas in the line R33F06 reporter expression was irregularly detected on ISNb or SNa nerve branches in small subsets of abdominal hemisegments. Through complementation test with a Sema1a loss-of-function allele, we found that neuronal expression of Sema-1a driven by each of R34A03 and R32H10 restores robustly the CNS and PNS motor axon guidance defects observed in Sema-1a homozygous mutants. However, when wild-type Sema-1a is expressed by R33F06 in Sema-1a mutants, the Sema-1a PNS axon guidance phenotypes are partially rescued while the Sema-1a CNS axon guidance defects are completely rescued. These results suggest that in a redundant manner, the CREs, R34A03, R32H10, and R33F06 govern the Sema-1a expression required for the axon guidance function of Sema-1a during embryonic neural development.
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Affiliation(s)
- Young Gi Hong
- Division of Life Sciences (Molecular Biology Major), Jeonbuk National University, Jeonju 54896, Korea
| | - Bongsu Kang
- Division of Life Sciences (Molecular Biology Major), Jeonbuk National University, Jeonju 54896, Korea
- Department of Bioactive Material Sciences and Research Center of Bioactive Materials, Jeonbuk National University, Jeonju 54896, Korea
| | - Seongsoo Lee
- Gwangju Center, Korea Basic Science Institute, Gwangju 61186, Korea
| | - Youngseok Lee
- Department of Bio and Fermentation Convergence Technology, BK21 PLUS Project, Kookmin University, Seoul 02707, Korea
| | - Bong-Gun Ju
- Department of Life Science, Sogang University, Seoul 04107, Korea
| | - Sangyun Jeong
- Division of Life Sciences (Molecular Biology Major), Jeonbuk National University, Jeonju 54896, Korea
- Department of Bioactive Material Sciences and Research Center of Bioactive Materials, Jeonbuk National University, Jeonju 54896, Korea
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Long H, Yoshikawa S, Thomas JB. Equivalent Activities of Repulsive Axon Guidance Receptors. J Neurosci 2016; 36:1140-50. [PMID: 26818503 PMCID: PMC4728722 DOI: 10.1523/jneurosci.3406-15.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 11/12/2015] [Accepted: 12/07/2015] [Indexed: 01/31/2023] Open
Abstract
Receptors on the growth cone at the leading edge of elongating axons play critical guidance roles by recognizing cues via their extracellular domains and transducing signals via their intracellular domains, resulting in changes in direction of growth. An important concept to have emerged in the axon guidance field is the importance of repulsion as a major guidance mechanism. Given the number and variety of different repulsive receptors, it is generally thought that there are likely to be qualitative differences in the signals they transduce. However, the nature of these possible differences is unknown. By creating chimeras using the extracellular and intracellular domains of three different Drosophila repulsive receptors, Unc5, Roundabout (Robo), and Derailed (Drl) and expressing them in defined cells within the embryonic nervous system, we examined the responses elicited by their intracellular domains systematically. Surprisingly, we found no qualitative differences in growth cone response or axon growth, suggesting that, despite their highly diverged sequences, each intracellular domain elicits repulsion via a common pathway. In terms of the signaling pathway(s) used by the repulsive receptors, mutations in the guanine nucleotide exchange factor Trio strongly enhance the repulsive activity of all three intracellular domains, suggesting that repulsion by Unc5, Robo, and Drl, and perhaps repulsion in general, involves Trio activity. SIGNIFICANCE STATEMENT A prevailing concept that has emerged in the axon guidance field is the importance of repulsion as a guidance mechanism for steering axons to their appropriate targets. Given the number and variety of different repulsive receptors, it is generally thought that there are differences in the signals that they transduce. However, this has never been tested directly. We have used the advanced genetics of Drosophila to compare directly the outputs of different repulsive receptors. Surprisingly, we found no qualitative differences in receptor-mediated repulsion, suggesting that, despite their highly diverged domain structure, each receptor couples to a common repulsive pathway. We went on to show that this common pathway involves Trio, a guanine nucleotide exchange factor known to promote cytoskeletal remodeling.
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Affiliation(s)
- Hong Long
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037
| | - Shingo Yoshikawa
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037
| | - John B Thomas
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037
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Yoshikawa S, Long H, Thomas JB. A subset of interneurons required for Drosophila larval locomotion. Mol Cell Neurosci 2015; 70:22-9. [PMID: 26621406 DOI: 10.1016/j.mcn.2015.11.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 11/28/2022] Open
Abstract
Efforts to define the neural circuits generating locomotor behavior have produced an initial understanding of some of the components within the spinal cord, as well as a basic understanding of several invertebrate motor pattern generators. However, how these circuits are assembled during development is poorly understood. We are defining the neural circuit that generates larval locomotion in the genetically tractable fruit fly Drosophila melanogaster to study locomotor circuit development. Forward larval locomotion involves a stereotyped posterior-to-anterior segmental translocation of body wall muscle contraction and is generated by a relatively small number of identified muscles, motor and sensory neurons, plus an unknown number of the ~270 bilaterally-paired interneurons per segment of the 1st instar larva. To begin identifying the relevant interneurons, we have conditionally inactivated synaptic transmission of interneuron subsets and assayed for the effects on locomotion. From this screen we have identified a subset of 25 interneurons per hemisegment, called the lateral locomotor neurons (LLNs), that are required for locomotion. Both inactivation and constitutive activation of the LLNs disrupt locomotion, indicating that patterned output of the LLNs is required. By expressing a calcium indicator in the LLNs, we found that they display a posterior-to-anterior wave of activity within the CNS corresponding to the segmental translocation of the muscle contraction wave. Identification of the LLNs represents the first step toward elucidating the circuit generating larval locomotion.
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Affiliation(s)
- Shingo Yoshikawa
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Hong Long
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - John B Thomas
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, United States.
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Winchell CJ, Jacobs DK. Expression of the Lhx genes apterous and lim1 in an errant polychaete: implications for bilaterian appendage evolution, neural development, and muscle diversification. EvoDevo 2013; 4:4. [PMID: 23369627 PMCID: PMC3579752 DOI: 10.1186/2041-9139-4-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 12/03/2012] [Indexed: 11/10/2022] Open
Abstract
UNLABELLED BACKGROUND Arthropod and vertebrate appendages appear to have evolved via parallel co-option of a plesiomorphic gene regulatory network. Our previous work implies that annelids evolved unrelated appendage-forming mechanisms; we therefore found no support for homology of parapodia and arthropodia at the level of the whole appendage. We expand on that study here by asking whether expression of the LIM homeobox (Lhx) genes apterous and lim1 in the annelid Neanthes arenaceodentata supports homology of the dorsal branches as well as the proximodistal axes of parapodia and arthropodia. In addition, we explore whether the neural expression of apterous and lim1 in Neanthes supports the putative ancestral function of the Lhx gene family in regulating the differentiation and maintenance of neuronal subtypes. RESULTS Both genes exhibit continuous expression in specific portions of the developing central nervous system, from hatching to at least the 13-chaetiger stage. For example, nerve cord expression occurs in segmentally iterated patterns consisting of diffuse sets of many lim1-positive cells and comparatively fewer, clustered pairs of apterous-positive cells. Additionally, continuous apterous expression is observed in presumed neurosecretory ganglia of the posterior brain, while lim1 is continuously expressed in stomatogastric ganglia of the anterior brain. apterous is also expressed in the jaw sacs, dorsal parapodial muscles, and a presumed pair of cephalic sensory organs, whereas lim1 is expressed in multiple pharyngeal ganglia, the segmental peripheral nervous system, neuropodial chaetal sac muscles, and parapodial ligules. CONCLUSIONS The early and persistent nervous system expression of apterous and lim1 in Neanthes juveniles supports conservation of Lhx function in bilaterian neural differentiation and maintenance. Our results also suggest that diversification of parapodial muscle precursors involves a complementary LIM code similar to those generating distinct neuronal identities in fly and mouse nerve cords. Expression of apterous and lim1 in discrete components of developing parapodia is intriguing but does not map to comparable expression of these genes in developing arthropod appendages. Thus, annelid and arthropod appendage development apparently evolved, in part, via distinct co-option of the neuronal regulatory architecture. These divergent patterns of apterous and lim1 activity seemingly reflect de novo origins of parapodia and arthropodia, although we discuss alternative hypotheses.
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Affiliation(s)
- Christopher J Winchell
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 621 Charles E Young Drive South, Los Angeles, CA 90095-1606, USA
- Present address: Department of Molecular and Cell Biology, University of California, Berkeley, 515 LSA #3200, Berkeley, CA 94720-3200, USA
| | - David K Jacobs
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 621 Charles E Young Drive South, Los Angeles, CA 90095-1606, USA
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Kühne C, Puk O, Graw J, Hrabě de Angelis M, Schütz G, Wurst W, Deussing JM. Visualizing corticotropin-releasing hormone receptor type 1 expression and neuronal connectivities in the mouse using a novel multifunctional allele. J Comp Neurol 2012; 520:3150-80. [DOI: 10.1002/cne.23082] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Foronda D, Martín P, Sánchez-Herrero E. Drosophila Hox and sex-determination genes control segment elimination through EGFR and extramacrochetae activity. PLoS Genet 2012; 8:e1002874. [PMID: 22912593 PMCID: PMC3415437 DOI: 10.1371/journal.pgen.1002874] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 06/18/2012] [Indexed: 11/20/2022] Open
Abstract
The formation or suppression of particular structures is a major change occurring in development and evolution. One example of such change is the absence of the seventh abdominal segment (A7) in Drosophila males. We show here that there is a down-regulation of EGFR activity and fewer histoblasts in the male A7 in early pupae. If this activity is elevated, cell number increases and a small segment develops in the adult. At later pupal stages, the remaining precursors of the A7 are extruded under the epithelium. This extrusion requires the up-regulation of the HLH protein Extramacrochetae and correlates with high levels of spaghetti-squash, the gene encoding the regulatory light chain of the non-muscle myosin II. The Hox gene Abdominal-B controls both the down-regulation of spitz, a ligand of the EGFR pathway, and the up-regulation of extramacrochetae, and also regulates the transcription of the sex-determining gene doublesex. The male Doublesex protein, in turn, controls extramacrochetae and spaghetti-squash expression. In females, the EGFR pathway is also down-regulated in the A7 but extramacrochetae and spaghetti-squash are not up-regulated and extrusion of precursor cells is almost absent. Our results show the complex orchestration of cellular and genetic events that lead to this important sexually dimorphic character change.
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Affiliation(s)
| | | | - Ernesto Sánchez-Herrero
- Centro de Biología Molecular Severo Ochoa (C.S.I.C.-U.A.M.), Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
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Coe genes are expressed in differentiating neurons in the central nervous system of protostomes. PLoS One 2011; 6:e21213. [PMID: 21695052 PMCID: PMC3117877 DOI: 10.1371/journal.pone.0021213] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 05/23/2011] [Indexed: 11/19/2022] Open
Abstract
Genes of the coe (collier/olfactory/early B-cell factor) family encode Helix-Loop-Helix transcription factors that are widely conserved in metazoans and involved in many developmental processes, neurogenesis in particular. Whereas their functions during vertebrate neural tube formation have been well documented, very little is known about their expression and role during central nervous system (CNS) development in protostomes. Here we characterized the CNS expression of coe genes in the insect Drosophila melanogaster and the polychaete annelid Platynereis dumerilii, which belong to different subgroups of protostomes and show strikingly different modes of development. In the Drosophila ventral nerve cord, we found that the Collier-expressing cells form a subpopulation of interneurons with diverse molecular identities and neurotransmitter phenotypes. We also demonstrate that collier is required for the proper differentiation of some interneurons belonging to the Eve-Lateral cluster. In Platynereis dumerilii, we cloned a single coe gene, Pdu-coe, and found that it is exclusively expressed in post mitotic neural cells. Using an original technique of in silico 3D registration, we show that Pdu-coe is co-expressed with many different neuronal markers and therefore that, like in Drosophila, its expression defines a heterogeneous population of neurons with diverse molecular identities. Our detailed characterization and comparison of coe gene expression in the CNS of two distantly-related protostomes suggest conserved roles of coe genes in neuronal differentiation in this clade. As similar roles have also been observed in vertebrates, this function was probably already established in the last common ancestor of all bilaterians.
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Stevenson IH, Körding KP. On the similarity of functional connectivity between neurons estimated across timescales. PLoS One 2010; 5:e9206. [PMID: 20174620 PMCID: PMC2823767 DOI: 10.1371/journal.pone.0009206] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Accepted: 01/27/2010] [Indexed: 11/18/2022] Open
Abstract
A central objective in neuroscience is to understand how neurons interact. Such functional interactions have been estimated using signals recorded with different techniques and, consequently, different temporal resolutions. For example, spike data often have sub-millisecond resolution while some imaging techniques may have a resolution of many seconds. Here we use multi-electrode spike recordings to ask how similar functional connectivity inferred from slower timescale signals is to the one inferred from fast timescale signals. We find that functional connectivity is relatively robust to low-pass filtering—dropping by about 10% when low pass filtering at 10 hz and about 50% when low pass filtering down to about 1 Hz—and that estimates are robust to high levels of additive noise. Moreover, there is a weak correlation for physiological filters such as hemodynamic or Ca2+ impulse responses and filters based on local field potentials. We address the origin of these correlations using simulation techniques and find evidence that the similarity between functional connectivity estimated across timescales is due to processes that do not depend on fast pair-wise interactions alone. Rather, it appears that connectivity on multiple timescales or common-input related to stimuli or movement drives the observed correlations. Despite this qualification, our results suggest that techniques with intermediate temporal resolution may yield good estimates of the functional connections between individual neurons.
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Affiliation(s)
- Ian H Stevenson
- Department of Physical Medicine and Rehabilitation, Rehabilitation Institute of Chicago, Chicago, Illinois, United States of America.
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Ohayon D, Pattyn A, Venteo S, Valmier J, Carroll P, Garces A. Zfh1 promotes survival of a peripheral glia subtype by antagonizing a Jun N-terminal kinase-dependent apoptotic pathway. EMBO J 2009; 28:3228-43. [PMID: 19745814 DOI: 10.1038/emboj.2009.247] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Accepted: 07/27/2009] [Indexed: 12/19/2022] Open
Abstract
In Drosophila subperineurial glia (SPG) ensheath and insulate the nerve. SPG is under strict cell cycle and survival control because cell division or death of such a cell type would compromise the integrity of the blood-nerve barrier. The mechanisms underlying the survival of SPG remain unknown. Here, we show that the embryonic peripheral glia expresses the Zfh1 transcription factor, and in zfh1 mutants a particular SPG subtype, ePG10, undergoes apoptosis. Our findings show that in ePG10, Zfh1 represses the pro-apoptotic RHG-motif gene reaper in a cell-autonomous manner. Zfh1 also blocks the activation of the Jun N-terminal kinase (JNK) pathway, and reducing or enhancing JNK signalling in zfh1 mutants prevents or promotes ePG10 apoptosis. Our study shows a novel function for Zfh1 as an anti-apoptotic molecule and uncovers a cryptic JNK-dependent apoptotic programme in ePG10, which is normally blocked by Zfh1. We propose that, in cells such as SPG that do not undergo self-renewal and survive long periods, transcriptional control of RHG-motif gene expression together with fine tuning of JNK signalling is crucial for cell survival.
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Affiliation(s)
- David Ohayon
- INSERM U583, INM-Hopital St Eloi, 80 rue Augustin Fliche, Montpellier Cedex, France
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Abstract
A central aim of neuroscience is to map neural circuits, in order to learn how they account for mental activities and behaviours and how alterations in them lead to neurological and psychiatric disorders. However, the methods that are currently available for visualizing circuits have severe limitations that make it extremely difficult to extract precise wiring diagrams from histological images. Here we review recent advances in this area, along with some of the opportunities that these advances present and the obstacles that remain.
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Rolls MM, Satoh D, Clyne PJ, Henner AL, Uemura T, Doe CQ. Polarity and intracellular compartmentalization of Drosophila neurons. Neural Dev 2007; 2:7. [PMID: 17470283 PMCID: PMC1868948 DOI: 10.1186/1749-8104-2-7] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Accepted: 04/30/2007] [Indexed: 11/16/2022] Open
Abstract
Background Proper neuronal function depends on forming three primary subcellular compartments: axons, dendrites, and soma. Each compartment has a specialized function (the axon to send information, dendrites to receive information, and the soma is where most cellular components are produced). In mammalian neurons, each primary compartment has distinctive molecular and morphological features, as well as smaller domains, such as the axon initial segment, that have more specialized functions. How neuronal subcellular compartments are established and maintained is not well understood. Genetic studies in Drosophila have provided insight into other areas of neurobiology, but it is not known whether flies are a good system in which to study neuronal polarity as a comprehensive analysis of Drosophila neuronal subcellular organization has not been performed. Results Here we use new and previously characterized markers to examine Drosophila neuronal compartments. We find that: axons and dendrites can accumulate different microtubule-binding proteins; protein synthesis machinery is concentrated in the cell body; pre- and post-synaptic sites localize to distinct regions of the neuron; and specializations similar to the initial segment are present. In addition, we track EB1-GFP dynamics and determine microtubules in axons and dendrites have opposite polarity. Conclusion We conclude that Drosophila will be a powerful system to study the establishment and maintenance of neuronal compartments.
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Affiliation(s)
- Melissa M Rolls
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, USA
- Department of Biochemistry and Molecular Biology, Penn State, University Park, USA
| | - Daisuke Satoh
- Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Peter J Clyne
- Department of Biochemistry and Biophysics, University of California, San Francisco, USA
| | - Astra L Henner
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, USA
| | - Tadashi Uemura
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Chris Q Doe
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, USA
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Baumgardt M, Miguel-Aliaga I, Karlsson D, Ekman H, Thor S. Specification of neuronal identities by feedforward combinatorial coding. PLoS Biol 2007; 5:e37. [PMID: 17298176 PMCID: PMC1790951 DOI: 10.1371/journal.pbio.0050037] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Accepted: 12/06/2006] [Indexed: 12/21/2022] Open
Abstract
Neuronal specification is often seen as a multistep process: earlier regulators confer broad neuronal identity and are followed by combinatorial codes specifying neuronal properties unique to specific subtypes. However, it is still unclear whether early regulators are re-deployed in subtype-specific combinatorial codes, and whether early patterning events act to restrict the developmental potential of postmitotic cells. Here, we use the differential peptidergic fate of two lineage-related peptidergic neurons in the Drosophila ventral nerve cord to show how, in a feedforward mechanism, earlier determinants become critical players in later combinatorial codes. Amongst the progeny of neuroblast 5–6 are two peptidergic neurons: one expresses FMRFamide and the other one expresses Nplp1 and the dopamine receptor DopR. We show the HLH gene collier functions at three different levels to progressively restrict neuronal identity in the 5–6 lineage. At the final step, collier is the critical combinatorial factor that differentiates two partially overlapping combinatorial codes that define FMRFamide versus Nplp1/DopR identity. Misexpression experiments reveal that both codes can activate neuropeptide gene expression in vast numbers of neurons. Despite their partially overlapping composition, we find that the codes are remarkably specific, with each code activating only the proper neuropeptide gene. These results indicate that a limited number of regulators may constitute a potent combinatorial code that dictates unique neuronal cell fate, and that such codes show a surprising disregard for many global instructive cues. By studying the differential peptidergic fate of two lineage-related neurons in theDrosophila ventral nerve cord, the authors provide deeper insights into how, in a feedforward mechanism, earlier developmental determinants become critical players in later combinatorial codes defining cell identity. The nervous system contains a daunting number of different cell types, perhaps as many as 10,000 in mammals, far outnumbering regulatory genes in many animal species. Studies of the determinants of cell fate in many systems during the last decade have supported the conclusion that cell fate is not determined by any one regulatory gene, but results from the combinatorial action of several regulators. Many questions about the nature of such codes, however, remain. It is not known, for example, how complex such codes are or how they are established. It is also unclear whether they are confined in their action or if they act outside of their normal context. To address these outstanding issues, we have used two unique subsets of Drosophila neurons, identifiable by their specific expression of two different neuropeptide genes. We have identified two partially overlapping and relatively simple codes, consisting of four to seven regulators that act to specify these two cell types. Intriguingly, specification is achieved in a feedforward manner such that A activates B, followed by A/B activating C, and A/B/C activating D. Each code is surprisingly potent, and can ectopically activate neuropeptide gene expression in a variety of neurons, with a surprising disregard for many early patterning events.
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Affiliation(s)
- Magnus Baumgardt
- Division of Molecular Genetics, Department of Physics, Chemistry and Biology, Linkoping University, Linkoping, Sweden
| | - Irene Miguel-Aliaga
- Division of Molecular Genetics, Department of Physics, Chemistry and Biology, Linkoping University, Linkoping, Sweden
| | - Daniel Karlsson
- Division of Molecular Genetics, Department of Physics, Chemistry and Biology, Linkoping University, Linkoping, Sweden
| | - Helen Ekman
- Division of Molecular Genetics, Department of Physics, Chemistry and Biology, Linkoping University, Linkoping, Sweden
| | - Stefan Thor
- Division of Molecular Genetics, Department of Physics, Chemistry and Biology, Linkoping University, Linkoping, Sweden
- * To whom correspondence should be addressed. E-mail:
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Characterizing exons 11 and 1 promoters of the mu opioid receptor (Oprm) gene in transgenic mice. BMC Mol Biol 2006; 7:41. [PMID: 17101047 PMCID: PMC1657025 DOI: 10.1186/1471-2199-7-41] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Accepted: 11/13/2006] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The complexity of the mouse mu opioid receptor (Oprm) gene was demonstrated by the identification of multiple alternatively spliced variants and promoters. Our previous studies have identified a novel promoter, exon 11 (E11) promoter, in the mouse Oprm gene. The E11 promoter is located approximately 10 kb upstream of the exon 1 (E1) promoter. The E11 promoter controls the expression of nine splice variants in the mouse Oprm gene. Distinguished from the TATA-less E1 promoter, the E11 promoter resembles a typical TATA-containing eukaryote class II promoter. The aim of this study is to further characterize the E11 and E1 promoters in vivo using a transgenic mouse model. RESULTS We constructed a approximately 20 kb transgenic construct in which a 3.7 kb E11 promoter region and an 8.9 kb E1 promoter region controlled expression of tau/LacZ and tau/GFP reporters, respectively. The construct was used to establish a transgenic mouse line. The expression of the reporter mRNAs, determined by a RT-PCR approach, in the transgenic mice during embryonic development displayed a temporal pattern similar to that of the endogenous promoters. X-gal staining for tau/LacZ reporter and GFP imaging for tau/GFP reporter showed that the transgenic E11 and E1 promoters were widely expressed in various regions of the central nervous system (CNS). The distribution of tau/GFP reporter in the CNS was similar to that of MOR-1-like immunoreactivity using an exon 4-specific antibody. However, differential expression of both promoters was observed in some CNS regions such as the hippocampus and substantia nigra, suggesting that the E11 and E1 promoters were regulated differently in these regions. CONCLUSION We have generated a transgenic mouse line to study the E11 and E1 promoters in vivo using tau/LacZ and tau/GFP reporters. The reasonable relevance of the transgenic model was demonstrated by the temporal and spatial expression of the transgenes as compared to those of the endogenous transcripts. We believe that these transgenic mice will provide a useful model for further characterizing the E11 and E1 promoter in vivo under different physiological and pathological circumstances such as chronic opioid treatment and chronic pain models.
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16
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Xu J, Zhu Y, Heinemann SF. Identification of sequence motifs that target neuronal nicotinic receptors to dendrites and axons. J Neurosci 2006; 26:9780-93. [PMID: 16988049 PMCID: PMC6674458 DOI: 10.1523/jneurosci.0840-06.2006] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) belong to a family of ligand-gated ion channels that play important roles in central and peripheral nervous systems. The subcellular distribution of neuronal nAChRs has important implications for function and is not well understood. Here, we analyzed the targeting of two major types of neuronal nAChRs by expressing epitope-tagged subunits in cultured hippocampal neurons. Surprisingly, the alpha7 nAChR (alpha7) and alpha4/beta2 nAChR (alpha4beta2) displayed distinct patterns of expression, with alpha7 targeted preferentially to the somatodendritic compartments, whereas alpha4beta2 was localized to both axonal and dendritic domains. When fused to CD4 or IL2RA (interleukin 2 receptor alpha subunit) proteins, which are normally distributed ubiquitously, the M3-M4 intracellular loop from the alpha7 subunit promoted dendritic expression, whereas the homologous M3-M4 loop from the alpha4 subunit led to surface axonal expression. Systemic screening and alanine substitution further identified a 25-residue leucine motif ([DE]XXXL[LI]) containing an axonal targeting sequence within the alpha4 loop and a 48-residue dileucine and tyrosine motif (YXXØ) containing a dendritic targeting sequence from the alpha7 loop. These results provide valuable information in understanding diverse roles of neuronal nAChRs in mediating and modulating synaptic transmission, synaptic plasticity, and nicotine addiction.
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Affiliation(s)
- Jian Xu
- Molecular Neurobiology Laboratory, The Salk Institute, La Jolla, California 92037
| | - Yongling Zhu
- Molecular Neurobiology Laboratory, The Salk Institute, La Jolla, California 92037
| | - Stephen F. Heinemann
- Molecular Neurobiology Laboratory, The Salk Institute, La Jolla, California 92037
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17
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Allan DW, Park D, St Pierre SE, Taghert PH, Thor S. Regulators acting in combinatorial codes also act independently in single differentiating neurons. Neuron 2005; 45:689-700. [PMID: 15748845 DOI: 10.1016/j.neuron.2005.01.026] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Revised: 12/17/2004] [Accepted: 01/20/2005] [Indexed: 10/25/2022]
Abstract
In the Drosophila ventral nerve cord, a small number of neurons express the LIM-homeodomain gene apterous (ap). These ap neurons can be subdivided based upon axon pathfinding and their expression of neuropeptidergic markers. ap, the zinc finger gene squeeze, the bHLH gene dimmed, and the BMP pathway are all required for proper specification of these cells. Here, using several ap neuron terminal differentiation markers, we have resolved how each of these factors contributes to ap neuron diversity. We find that these factors interact genetically and biochemically in subtype-specific combinatorial codes to determine certain defining aspects of ap neuron subtype identity. However, we also find that ap, dimmed, and squeeze additionally act independently of one another to specify certain other defining aspects of ap neuron subtype identity. Therefore, within single neurons, we show that single regulators acting in numerous molecular contexts differentially specify multiple subtype-specific traits.
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Affiliation(s)
- Douglas W Allan
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
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18
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Miguel-Aliaga I, Thor S. Segment-specific prevention of pioneer neuron apoptosis by cell-autonomous, postmitotic Hox gene activity. Development 2004; 131:6093-105. [PMID: 15537690 DOI: 10.1242/dev.01521] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In vertebrates, neurons often undergo apoptosis after differentiating and extending their axons. By contrast, in the developing nervous system of invertebrate embryos apoptosis typically occurs soon after cells are generated. Here, we show that the Drosophila dMP2 and MP1 pioneer neurons undergo segment-specific apoptosis at late embryonic stages, long after they have extended their axons and have performed their pioneering role in guiding follower axons. This segmental specificity is achieved by differential expression of the Hox gene Abdominal B, which in posterior segments prevents pioneer neuron death postmitotically and cell-autonomously by repressing the RHG-motif cell death activators reaper and grim. Our results identify the first clear case of a cell-autonomous and anti-apoptotic role for a Hox gene in vivo. In addition, they provide a novel mechanism linking Hox positional information to differences in neuronal architecture along the anteroposterior axis by the selective elimination of mature neurons.
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Affiliation(s)
- Irene Miguel-Aliaga
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
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19
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Miguel-Aliaga I, Allan DW, Thor S. Independent roles of the dachshund and eyes absent genes in BMP signaling, axon pathfinding and neuronal specification. Development 2004; 131:5837-48. [PMID: 15525669 DOI: 10.1242/dev.01447] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the Drosophila nerve cord, a subset of neurons expresses the neuropeptide FMRFamide related (Fmrf). Fmrf expression is controlled by a combinatorial code of intrinsic factors and an extrinsic BMP signal. However, this previously identified code does not fully explain the regulation of Fmrf. We have found that the Dachshund (Dac) and Eyes Absent (Eya) transcription co-factors participate in this combinatorial code. Previous studies have revealed an intimate link between Dac and Eya during eye development. Here, by analyzing their function in neurons with multiple phenotypic markers, we demonstrate that they play independent roles in neuronal specification, even within single cells. dac is required for high-level Fmrf expression, and acts potently together with apterous and BMP signaling to trigger Fmrf expression ectopically, even in motoneurons. By contrast, eya regulates Fmrf expression by controlling both axon pathfinding and BMP signaling, but cannot trigger Fmrf ectopically. Thus, we show that dac and eya perform entirely different functions in a single cell type to ultimately regulate a single phenotypic outcome.
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Affiliation(s)
- Irene Miguel-Aliaga
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
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20
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Velde K, Ross MW, Orsini JA, Parente EJ, Foley B, Richardson DW, Miselis RR. Tracing axons of peripheral nerves in rats: a potential technique to study the equine recurrent laryngeal nerve. J INVEST SURG 2004; 17:151-62. [PMID: 15204959 DOI: 10.1080/08941930490446937] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
To study the fascicular anatomy of peripheral nerves, three different groups of retrograde axonal tracers were evaluated: fluorophores, horseradish peroxidase conjugated to subunit B of cholera toxin (CT-HRP), and adeno-associated virus (AAV). The hindlimb nerves in rats served as a model to identify the most efficient tracer in regard to labeling axons within peripheral nerves. The rat's tibial and common peroneal nerves were injected with the different tracers and the sciatic nerve was subsequently examined for evidence of labeled axons. The CT-HRP clearly provided the best results in this rat model. Subsequently, CT-HRP was injected into the recurrent laryngeal nerve (RLN) of two horses in order to identify the location and distribution pattern of the RLN axons within the course of the cervical vagus nerve trunk. No labeling could be observed in either of the two horses.
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Affiliation(s)
- Karsten Velde
- New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania 19348-1692, USA.
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21
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Beirowski B, Berek L, Adalbert R, Wagner D, Grumme DS, Addicks K, Ribchester RR, Coleman MP. Quantitative and qualitative analysis of Wallerian degeneration using restricted axonal labelling in YFP-H mice. J Neurosci Methods 2004; 134:23-35. [PMID: 15102500 DOI: 10.1016/j.jneumeth.2003.10.016] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2003] [Revised: 09/23/2003] [Accepted: 10/23/2003] [Indexed: 11/28/2022]
Abstract
We investigated the usefulness of YFP-H transgenic mice [Neuron 28 (2000) 41] which express yellow fluorescent protein (YFP) in a restricted subset of neurons to study Wallerian degeneration in the PNS. Quantification of YFP positive axons and myelin basic protein (MBP) immunocytochemistry revealed that YFP was randomly distributed to approximately 3% of myelinated motor and sensory fibres. Axotomy-induced Wallerian degeneration appeared as fragmentation of fluorescent signals in individual YFP positive axons with a morphology and timing similar to Wallerian degeneration observed by more traditional methods. In YFP-H transgenic mice co-expressing a high dosage of WldS, a chimeric gene that protects from Wallerian degeneration [Nat Neurosci. 4 (2001) 1199], axonal fragmentation in distal tibial nerves after sciatic nerve axotomy was approximately 10 times delayed. Considerable retardations of Wallerian degeneration using the same transgenic expression system were also observed in cultures of nerve explants, enabling in vitro real-time imaging of axonal fragmentation. Remarkably, single YFP-labelled axons could be traced in peripheral nerves for unusually long distances of up to 2.9 cm exploiting confocal fluorescence imaging. Altogether transgenic YFP-H mice prove to be a valuable tool to study mechanisms of Wallerian degeneration in vivo and in vitro.
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Affiliation(s)
- Bogdan Beirowski
- Center for Molecular Medicine Cologne and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50674 Cologne, Germany.
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22
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Thaler JP, Koo SJ, Kania A, Lettieri K, Andrews S, Cox C, Jessell TM, Pfaff SL. A Postmitotic Role for Isl-Class LIM Homeodomain Proteins in the Assignment of Visceral Spinal Motor Neuron Identity. Neuron 2004; 41:337-50. [PMID: 14766174 DOI: 10.1016/s0896-6273(04)00011-x] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Revised: 11/04/2003] [Accepted: 12/29/2003] [Indexed: 01/03/2023]
Abstract
LIM homeobox genes have a prominent role in the regulation of neuronal subtype identity and distinguish motor neuron subclasses in the embryonic spinal cord. We have investigated the role of Isl-class LIM homeodomain proteins in motor neuron diversification using mouse genetic methods. All spinal motor neuron subtypes initially express both Isl1 and Isl2, but Isl2 is rapidly downregulated by visceral motor neurons. Mouse embryos lacking Isl2 function exhibit defects in the migration and axonal projections of thoracic level motor neurons that appear to reflect a cell-autonomous switch from visceral to somatic motor neuron character. Additional genetic mutations that reduce or eliminate both Isl1 and Isl2 activity result in more pronounced defects in visceral motor neuron generation and erode somatic motor neuron character. Thus, an early phase of high Isl expression and activity in newly generated motor neurons permits the diversification of visceral and somatic motor neuron subtypes in the developing spinal cord.
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Affiliation(s)
- Joshua P Thaler
- Gene Expression Laboratory, The Salk Institute, La Jolla, CA 92037, USA
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23
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Wilson Y, Nag N, Davern P, Oldfield BJ, McKinley MJ, Greferath U, Murphy M. Visualization of functionally activated circuitry in the brain. Proc Natl Acad Sci U S A 2002; 99:3252-7. [PMID: 11867719 PMCID: PMC122505 DOI: 10.1073/pnas.042701199] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have used a transgenic approach to visualize functionally activated neurons and their projections. The transgenic mice contain a tau-lacZ fusion gene regulated by the promoter for c-fos, an immediate early gene that is rapidly induced in neurons after functional stimulation. Constitutive expression of beta-galactosidase (beta-gal), the lacZ product, was low and in accord with previous reports of c-fos expression. However, expression of beta-gal in positive neurons was clearly in cell bodies, axons, and dendrites. Treatment of the mice with kainic acid, a strong inducer of c-fos expression, resulted in high induction of beta-gal. beta-gal was induced in the same defined populations of neurons in the brain as those that express c-fos after kainic acid induction. Furthermore, the pattern of beta-gal expression within the neurons changed over time after kainic acid treatment. Early after kainate treatment, beta-gal was found mainly in cell bodies; at later times, expression extended further along the neuronal processes. This expression pattern is consistent with induction and anterograde transport of the Fos-Tau-beta-gal protein in the neurons. To test whether a functionally activated pathway could be visualized, transgenic mice were deprived of water, which activates nuclei involved in body fluid homeostasis. beta-gal induction was traced in neurons and their processes in the lamina terminalis, in magnocellular neurons of the supraoptic and paraventricular nuclei, and in their projections to the posterior pituitary gland. This strategy allowed the mapping of an activated osmoregulatory pathway. This transgenic approach may have general application in the mapping of functionally activated circuitry in the brain.
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Affiliation(s)
- Yvette Wilson
- Department of Anatomy and Cell Biology and Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, 3010, Australia
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24
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Abstract
The central nervous system (CNS) of higher organisms is bilaterally-symmetric. The transfer of information between the two sides of the nervous system occurs through commissures formed by neurons that project axons across the midline to the contralateral side of the CNS. Interestingly, these axons cross the midline only once. Other neurons extend axons that never cross the midline; they project exclusively on their own (ipsilateral) side of the CNS. Thus, the midline is an important choice point for several classes of pathfinding axons. Recent studies demonstrate that specialized midline cells play critical roles in regulating the guidance of both crossing and non-crossing axons at the ventral midline of the developing vertebrate spinal cord and the Drosophila ventral nerve cord. For example, these cells secrete attractive cues that guide commissural axons over long distances to the midline of the CNS. Furthermore, short-range interactions between guidance cues present on the surfaces of midline cells, and their receptors expressed on the surfaces of pathfinding axons, allow commissural axons to cross the midline only once and prevent ipsilaterally-projecting axons from entering the midline. Remarkably, the molecular composition of commissural axon surfaces is dynamically-altered as they cross the midline. Consequently, commissural axons become responsive to repulsive midline guidance cues that they had previously ignored on the ipsilateral side of the midline. Concomitantly, commissural axons lose responsiveness to attractive guidance cues that had initially attracted them to the midline. Thus, these exquisitely regulated guidance systems prevent commissural axons from lingering within the confines of the midline and allow them to pioneer an appropriate pathway on the contralateral side of the CNS. Many aspects of midline guidance are controlled by mechanistically and evolutionarily-conserved ligand-receptor systems. Strikingly, recent studies demonstrate that these receptors are modular; the ectodomains determine ligand recognition and the cytoplasmic domains specify the response of an axon to a given guidance cue. Despite rapid and dramatic progress in elucidating the molecular mechanisms that control midline guidance, many questions remain.
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Affiliation(s)
- Z Kaprielian
- Departments of Pathology and Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY 10461, USA.
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25
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Feng G, Mellor RH, Bernstein M, Keller-Peck C, Nguyen QT, Wallace M, Nerbonne JM, Lichtman JW, Sanes JR. Imaging neuronal subsets in transgenic mice expressing multiple spectral variants of GFP. Neuron 2000; 28:41-51. [PMID: 11086982 DOI: 10.1016/s0896-6273(00)00084-2] [Citation(s) in RCA: 2394] [Impact Index Per Article: 99.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We generated transgenic mice in which red, green, yellow, or cyan fluorescent proteins (together termed XFPs) were selectively expressed in neurons. All four XFPs labeled neurons in their entirety, including axons, nerve terminals, dendrites, and dendritic spines. Remarkably, each of 25 independently generated transgenic lines expressed XFP in a unique pattern, even though all incorporated identical regulatory elements (from the thyl gene). For example, all retinal ganglion cells or many cortical neurons were XFP positive in some lines, whereas only a few ganglion cells or only layer 5 cortical pyramids were labeled in others. In some lines, intense labeling of small neuronal subsets provided a Golgi-like vital stain. In double transgenic mice expressing two different XFPs, it was possible to differentially label 3 neuronal subsets in a single animal.
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Affiliation(s)
- G Feng
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri 63110, USA
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