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Liberali P, Schier AF. The evolution of developmental biology through conceptual and technological revolutions. Cell 2024:S0092-8674(24)00632-9. [PMID: 38906136 DOI: 10.1016/j.cell.2024.05.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 06/23/2024]
Abstract
Developmental biology-the study of the processes by which cells, tissues, and organisms develop and change over time-has entered a new golden age. After the molecular genetics revolution in the 80s and 90s and the diversification of the field in the early 21st century, we have entered a phase when powerful technologies provide new approaches and open unexplored avenues. Progress in the field has been accelerated by advances in genomics, imaging, engineering, and computational biology and by emerging model systems ranging from tardigrades to organoids. We summarize how revolutionary technologies have led to remarkable progress in understanding animal development. We describe how classic questions in gene regulation, pattern formation, morphogenesis, organogenesis, and stem cell biology are being revisited. We discuss the connections of development with evolution, self-organization, metabolism, time, and ecology. We speculate how developmental biology might evolve in an era of synthetic biology, artificial intelligence, and human engineering.
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Affiliation(s)
- Prisca Liberali
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland.
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2
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LaBelle J, Wyatt T, Woo S. Endodermal cells use contact inhibition of locomotion to achieve uniform cell dispersal during zebrafish gastrulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.01.543209. [PMID: 37333383 PMCID: PMC10274714 DOI: 10.1101/2023.06.01.543209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The endoderm is one of the three primary germ layers that ultimately gives rise to the gastrointestinal and respiratory epithelia and other tissues. In zebrafish and other vertebrates, endodermal cells are initially highly migratory with only transient interactions among one other, but later converge together to form an epithelial sheet. Here, we show that during their early, migratory phase, endodermal cells actively avoid each other through contact inhibition of locomotion (CIL), a characteristic response consisting of 1) actin depolymerization and membrane retraction at the site of contact, 2) preferential actin polymerization along a cell-free edge, and 3) reorientation of migration away from the other cell. We found that this response is dependent on the Rho GTPase RhoA and EphA/ephrin-A signaling - expression of dominant-negative (DN) RhoA or treatment with the EphA inhibitor dasatinib resulted in behaviors consistent with loss of CIL, including increased contact duration times and decreased likelihood of migration reorientation after contact. Computational modeling predicted that CIL is required to achieve the efficient and uniform dispersal characteristic of endodermal cells. Consistent with our model, we found that loss of CIL via DN RhoA expression resulted in irregular clustering of cells within the endoderm. Together, our results suggest that endodermal cells use EphA2- and RhoA-dependent CIL as a cell dispersal and spacing mechanism, demonstrating how local interactions can give rise to tissue-scale patterns.
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Affiliation(s)
- Jesselynn LaBelle
- Quantiative and Systems Biology, University of California, Merced, CA USA
| | - Tom Wyatt
- Laboratoire Matière et Systèmes Complexes, UMR 7057 CNRS, Université de Paris, France
| | - Stephanie Woo
- Quantiative and Systems Biology, University of California, Merced, CA USA
- Department of Molecular Cell Biology, University of California, Merced, CA USA
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3
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Mu JD, Ma LX, Zhang Z, Qian X, Zhang QY, Ma LH, Sun TY. The factors affecting neurogenesis after stroke and the role of acupuncture. Front Neurol 2023; 14:1082625. [PMID: 36741282 PMCID: PMC9895425 DOI: 10.3389/fneur.2023.1082625] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/03/2023] [Indexed: 01/22/2023] Open
Abstract
Stroke induces a state of neuroplasticity in the central nervous system, which can lead to neurogenesis phenomena such as axonal growth and synapse formation, thus affecting stroke outcomes. The brain has a limited ability to repair ischemic damage and requires a favorable microenvironment. Acupuncture is considered a feasible and effective neural regulation strategy to improve functional recovery following stroke via the benign modulation of neuroplasticity. Therefore, we summarized the current research progress on the key factors and signaling pathways affecting neurogenesis, and we also briefly reviewed the research progress of acupuncture to improve functional recovery after stroke by promoting neurogenesis. This study aims to provide new therapeutic perspectives and strategies for the recovery of motor function after stroke based on neurogenesis.
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Affiliation(s)
- Jie-Dan Mu
- School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing, China
| | - Liang-Xiao Ma
- School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing, China,The Key Unit of State Administration of Traditional Chines Medicine, Evaluation of Characteristic Acupuncture Therapy, Beijing, China,*Correspondence: Liang-Xiao Ma ✉
| | - Zhou Zhang
- School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing, China
| | - Xu Qian
- School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing, China
| | - Qin-Yong Zhang
- School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing, China
| | - Ling-Hui Ma
- School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing, China
| | - Tian-Yi Sun
- School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing, China
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4
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Klein R, Wilkinson D, Herrera E. Editorial - Friedrich Bonhoeffer (1932-2021). Neuroscience 2023; 508:1-2. [PMID: 36427670 DOI: 10.1016/j.neuroscience.2022.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Rüdiger Klein
- Max-Planck Institute for Biological Intelligence, Am Klopferspitz 18, 82152 Martinsried, Germany
| | | | - Eloisa Herrera
- Instituto de Neurociencias (CSIC-UMH), Av. Ramón y Cajal s/n, San Juan de Alicante, Alicante, Spain.
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5
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Dumoulin A, Stoeckli ET. Looking for Guidance - Models and Methods to Study Axonal Navigation. Neuroscience 2023; 508:30-39. [PMID: 35940454 DOI: 10.1016/j.neuroscience.2022.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 01/17/2023]
Abstract
The molecular mechanisms of neural circuit formation have been of interest to Santiago Ramón y Cajal and thousands of neuroscientists sharing his passion for neural circuits ever since. Cajal was a brilliant observer and taught us about the connections and the morphology of neurons in the adult and developing nervous system. Clearly, we will not learn about molecular mechanisms by just looking at brain sections or cells in culture. Technically, we had to come a long way to today's possibilities that allow us to perturb target gene expression and watch the consequences of our manipulations on navigating axons in situ. In this review, we summarize landmark steps towards modern live-imaging approaches used to study the molecular basis of axon guidance.
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Affiliation(s)
- Alexandre Dumoulin
- Department of Molecular Life Sciences and Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Esther T Stoeckli
- Department of Molecular Life Sciences and Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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6
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Whitney IE, Butrus S, Dyer MA, Rieke F, Sanes JR, Shekhar K. Vision-Dependent and -Independent Molecular Maturation of Mouse Retinal Ganglion Cells. Neuroscience 2023; 508:153-173. [PMID: 35870562 PMCID: PMC10809145 DOI: 10.1016/j.neuroscience.2022.07.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 06/20/2022] [Accepted: 07/13/2022] [Indexed: 01/17/2023]
Abstract
The development and connectivity of retinal ganglion cells (RGCs), the retina's sole output neurons, are patterned by activity-independent transcriptional programs and activity-dependent remodeling. To inventory the molecular correlates of these influences, we applied high-throughput single-cell RNA sequencing (scRNA-seq) to mouse RGCs at six embryonic and postnatal ages. We identified temporally regulated modules of genes that correlate with, and likely regulate, multiple phases of RGC development, ranging from differentiation and axon guidance to synaptic recognition and refinement. Some of these genes are expressed broadly while others, including key transcription factors and recognition molecules, are selectively expressed by one or a few of the 45 transcriptomically distinct types defined previously in adult mice. Next, we used these results as a foundation to analyze the transcriptomes of RGCs in mice lacking visual experience due to dark rearing from birth or to mutations that ablate either bipolar or photoreceptor cells. 98.5% of visually deprived (VD) RGCs could be unequivocally assigned to a single RGC type based on their transcriptional profiles, demonstrating that visual activity is dispensable for acquisition and maintenance of RGC type identity. However, visual deprivation significantly reduced the transcriptomic distinctions among RGC types, implying that activity is required for complete RGC maturation or maintenance. Consistent with this notion, transcriptomic alternations in VD RGCs significantly overlapped with gene modules found in developing RGCs. Our results provide a resource for mechanistic analyses of RGC differentiation and maturation, and for investigating the role of activity in these processes.
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Affiliation(s)
- Irene E Whitney
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Salwan Butrus
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, USA
| | - Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Joshua R Sanes
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Karthik Shekhar
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Helen Wills Neuroscience Institute, California Institute for Quantitative Biosciences, QB3, Center for Computational Biology, University of California, Berkeley, CA 94720, USA; Biological Systems Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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7
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Sullivan KG, Bashaw GJ. Intracellular Trafficking Mechanisms that Regulate Repulsive Axon Guidance. Neuroscience 2023; 508:123-136. [PMID: 35863679 PMCID: PMC9839465 DOI: 10.1016/j.neuroscience.2022.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/01/2022] [Accepted: 07/13/2022] [Indexed: 01/17/2023]
Abstract
Friedrich Bonhoeffer made seminal contributions to the study of axon guidance in the developing nervous system. His discoveries of key cellular and molecular mechanisms that dictate wiring specificity laid the foundation for countless investigators who have followed in his footsteps. Perhaps his most significant contribution was the cloning and characterization of members of the conserved ephrin family of repulsive axon guidance cues. In this review, we highlight the major contributions that Bonhoeffer and his colleagues made to the field of axon guidance, and discuss ongoing investigations into the diverse array of mechanisms that ensure that axon repulsion is precisely regulated to allow for accurate pathfinding. Specifically, we focus our discussion on the post-translational regulation of two major families of repulsive axon guidance factors: ephrin ligands and their Eph receptors, and slit ligands and their Roundabout (Robo) receptors. We will give special emphasis to the ways in which regulated endocytic trafficking events allow navigating axons to adjust their responses to repellant signals and how these trafficking events are intimately related to receptor signaling. By highlighting parallels and differences between the regulation of these two important repulsive axon guidance pathways, we hope to identify key outstanding questions for future investigation.
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Affiliation(s)
- Kelly G Sullivan
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, United States
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, United States.
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8
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Godement P. A Stay in Friedrich Bonhoeffer's Lab in Tubingen in the Mid-eighties. Neuroscience 2023; 508:52-61. [PMID: 36464176 DOI: 10.1016/j.neuroscience.2022.11.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/15/2022] [Accepted: 11/23/2022] [Indexed: 12/03/2022]
Abstract
The main focus of research for which Friedrich Bonhoeffer's work is known in the Neuroscience community was pioneer experiments on how axonal projections could organize into "maps", what mechanisms are involved in axon guidance and involve gradients of guiding molecules, and isolation of the first such molecules, e.g. RAGS (ephrin A5) and RGM (repulsive guidance molecule). Other papers have described in detail these contributions as well as Friedrich Bonhoeffer's personality. In the mid-eighties, I made a 2-year stay in his lab and initiated a line of research on development of binocular connections in Mammals, particularly the guidance of retinal fibers to one or the other side of the brain. In this paper I recall these circumstances as they pertain to Neuroscience as it stood at the time, and explain as best as I can how his lab was a conducive setting for the discoveries made there and how Friedrich Bonhoeffer acted for me as a scientist and a tutor.
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Affiliation(s)
- Pierre Godement
- Centre National de la Recherche Scientifique, Paris, France.
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9
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Ros O, Nicol X. Axon pathfinding and targeting: (R)evolution of insights from in vitro assays. Neuroscience 2023; 508:110-122. [PMID: 36096337 DOI: 10.1016/j.neuroscience.2022.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 09/01/2022] [Accepted: 09/05/2022] [Indexed: 01/17/2023]
Abstract
Investigating axonal behaviors while neurons are connecting with each other has been a challenge since the early studies on nervous system development. While molecule-driven axon pathfinding has been theorized by observing neurons at different developmental stages in vivo, direct observation and measurements of axon guidance behaviors required the invention of in vitro systems enabling to test the impact of molecules or cellular extracts on axons growing in vitro. With time, the development of novel in vivo approaches has confirmed the mechanisms highlighted in culture and has led in vitro systems to be adapted for cellular processes that are still inaccessible in intact organisms. We here review the evolution of these in vitro assays, which started with crucial contributions from the Bonhoeffer lab.
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Affiliation(s)
- Oriol Ros
- Universitat de Barcelona, Department of Cell Biology, Physiology and Immunology, Avinguda Diagonal 643, 08028 Barcelona, Catalonia, Spain
| | - Xavier Nicol
- Sorbonne Université, Inserm, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
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10
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Shuster SA, Li J, Chon UR, Sinantha-Hu MC, Luginbuhl DJ, Udeshi ND, Carey DK, Takeo YH, Xie Q, Xu C, Mani DR, Han S, Ting AY, Carr SA, Luo L. In situ cell-type-specific cell-surface proteomic profiling in mice. Neuron 2022; 110:3882-3896.e9. [PMID: 36220098 PMCID: PMC9742329 DOI: 10.1016/j.neuron.2022.09.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 08/04/2022] [Accepted: 09/20/2022] [Indexed: 11/06/2022]
Abstract
Cell-surface proteins (CSPs) mediate intercellular communication throughout the lives of multicellular organisms. However, there are no generalizable methods for quantitative CSP profiling in specific cell types in vertebrate tissues. Here, we present in situ cell-surface proteome extraction by extracellular labeling (iPEEL), a proximity labeling method in mice that enables spatiotemporally precise labeling of cell-surface proteomes in a cell-type-specific environment in native tissues for discovery proteomics. Applying iPEEL to developing and mature cerebellar Purkinje cells revealed differential enrichment in CSPs with post-translational protein processing and synaptic functions in the developing and mature cell-surface proteomes, respectively. A proteome-instructed in vivo loss-of-function screen identified a critical, multifaceted role for Armh4 in Purkinje cell dendrite morphogenesis. Armh4 overexpression also disrupts dendrite morphogenesis; this effect requires its conserved cytoplasmic domain and is augmented by disrupting its endocytosis. Our results highlight the utility of CSP profiling in native mammalian tissues for identifying regulators of cell-surface signaling.
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Affiliation(s)
- S Andrew Shuster
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Program, Stanford University, CA 94305, USA
| | - Jiefu Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - URee Chon
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Program, Stanford University, CA 94305, USA
| | - Miley C Sinantha-Hu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - David J Luginbuhl
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Namrata D Udeshi
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | - Yukari H Takeo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Qijing Xie
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Program, Stanford University, CA 94305, USA
| | - Chuanyun Xu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - D R Mani
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Shuo Han
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Alice Y Ting
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Steven A Carr
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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11
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Genetic characterization of outbred Sprague Dawley rats and utility for genome-wide association studies. PLoS Genet 2022; 18:e1010234. [PMID: 35639796 PMCID: PMC9187121 DOI: 10.1371/journal.pgen.1010234] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 06/10/2022] [Accepted: 05/03/2022] [Indexed: 12/30/2022] Open
Abstract
Sprague Dawley (SD) rats are among the most widely used outbred laboratory rat populations. Despite this, the genetic characteristics of SD rats have not been clearly described, and SD rats are rarely used for experiments aimed at exploring genotype-phenotype relationships. In order to use SD rats to perform a genome-wide association study (GWAS), we collected behavioral data from 4,625 SD rats that were predominantly obtained from two commercial vendors, Charles River Laboratories and Harlan Sprague Dawley Inc. Using double-digest genotyping-by-sequencing (ddGBS), we obtained dense, high-quality genotypes at 291,438 SNPs across 4,061 rats. This genetic data allowed us to characterize the variation present in Charles River vs. Harlan SD rats. We found that the two populations are highly diverged (FST > 0.4). Furthermore, even for rats obtained from the same vendor, there was strong population structure across breeding facilities and even between rooms at the same facility. We performed multiple separate GWAS by fitting a linear mixed model that accounted for population structure and using meta-analysis to jointly analyze all cohorts. Our study examined Pavlovian conditioned approach (PavCA) behavior, which assesses the propensity for rats to attribute incentive salience to reward-associated cues. We identified 46 significant associations for the various metrics used to define PavCA. The surprising degree of population structure among SD rats from different sources has important implications for their use in both genetic and non-genetic studies. Outbred Sprague Dawley rats are among the most commonly used rats for neuroscience, physiology and pharmacological research; in the year 2020, 4,188 publications contained the keyword “Sprague Dawley”. Rats identified as “Sprague Dawley” are sold by several commercial vendors, including Charles River Laboratories and Harlan Sprague Dawley Inc. (now Envigo). Despite their widespread use, little is known about the genetic diversity of SD. We genotyped more than 4,000 SD rats, which we used for a genome-wide association study (GWAS) and to characterize genetic differences between SD rats from Charles River Laboratories and Harlan. Our analysis revealed extensive population structure both between and within vendors. The GWAS for Pavlovian conditioned approach (PavCA) identified a number of genome-wide significant loci for that complex behavioral trait. Our results demonstrate that, despite sharing an identical name, SD rats that are obtained from different vendors are very different. Future studies should carefully define the exact source of SD rats being used and may exploit their genetic diversity for genetic studies of complex traits.
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12
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Topographic map formation and the effects of NMDA receptor blockade in the developing visual system. Proc Natl Acad Sci U S A 2022; 119:2107899119. [PMID: 35193956 PMCID: PMC8872792 DOI: 10.1073/pnas.2107899119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2022] [Indexed: 11/18/2022] Open
Abstract
Studying the emergence of topographic organization in sensory maps has been constrained by spatial limitations of traditional anatomical and physiological techniques early in development in many animal models. Here, we have applied a high-resolution, noninvasive, in vivo calcium imaging approach to study the nascent retinotopic map in the larval Xenopus laevis retinotectal system. We performed longitudinal functional imaging of the three-dimensional organization of emerging retinotopic maps and assessed the effects of N-methyl-D-aspartate (NMDA) receptor blockade on map formation. Our results provide insights into early retinotopic map emergence and the role of NMDA receptors in the refinement of topographic gradients. The development of functional topography in the developing brain follows a progression from initially coarse to more precisely organized maps. To examine the emergence of topographically organized maps in the retinotectal system, we performed longitudinal visual receptive field mapping by calcium imaging in the optic tectum of GCaMP6-expressing transgenic Xenopus laevis tadpoles. At stage 42, just 1 d after retinal axons arrived in the optic tectum, a clear retinotopic azimuth map was evident. Animals were imaged over the following week at stages 45 and 48, over which time the tectal neuropil nearly doubled in length and exhibited more precise retinotopic organization. By microinjecting GCaMP6s messenger ribonucleic acid (mRNA) into one blastomere of two-cell stage embryos, we acquired bilateral mosaic tadpoles with GCaMP6s expression in postsynaptic tectal neurons on one side of the animal and in retinal ganglion cell axons crossing to the tectum on the opposite side. Longitudinal observation of retinotopic map emergence revealed the presence of orderly representations of azimuth and elevation as early as stage 42, although presynaptic inputs exhibited relatively less topographic organization than the postsynaptic component for the azimuth axis. Retinotopic gradients in the tectum became smoother between stages 42 and 45. Blocking N-methyl-D-aspartate (NMDA) receptor conductance by rearing tadpoles in MK-801 did not prevent the emergence of retinotopic maps, but it produced more discontinuous topographic gradients and altered receptive field characteristics. These results provide evidence that current through NMDA receptors is dispensable for coarse topographic ordering of retinotectal inputs but does contribute to the fine-scale organization of the retinotectal projection.
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Abstract
The Tabula Gallus is a proposed project that aims to create a map of every cell type in the chicken body and chick embryos. Chickens (Gallus gallus) are one of the most recognized model animals that recapitulate the development and physiology of mammals. The Tabula Gallus will generate a compendium of single-cell transcriptome data from Gallus gallus, characterize each cell type, and provide tools for the study of the biology of this species, similar to other ongoing cell atlas projects (Tabula Muris and Tabula Sapiens/Human Cell Atlas for mice and humans, respectively). The Tabula Gallus will potentially become an international collaboration between many researchers. This project will be useful for the basic scientific study of Gallus gallus and other birds (e.g., cell biology, molecular biology, developmental biology, neuroscience, physiology, oncology, virology, behavior, ecology, and evolution). It will eventually be beneficial for a better understanding of human health and diseases.
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14
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Ahmed G, Shinmyo Y. Multiple Functions of Draxin/Netrin-1 Signaling in the Development of Neural Circuits in the Spinal Cord and the Brain. Front Neuroanat 2021; 15:766911. [PMID: 34899198 PMCID: PMC8655782 DOI: 10.3389/fnana.2021.766911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 10/22/2021] [Indexed: 11/30/2022] Open
Abstract
Axon guidance proteins play key roles in the formation of neural circuits during development. We previously identified an axon guidance cue, named draxin, that has no homology with other axon guidance proteins. Draxin is essential for the development of various neural circuits including the spinal cord commissure, corpus callosum, and thalamocortical projections. Draxin has been shown to not only control axon guidance through netrin-1 receptors, deleted in colorectal cancer (Dcc), and neogenin (Neo1) but also modulate netrin-1-mediated axon guidance and fasciculation. In this review, we summarize the multifaceted functions of draxin and netrin-1 signaling in neural circuit formation in the central nervous system. Furthermore, because recent studies suggest that the distributions and functions of axon guidance cues are highly regulated by glycoproteins such as Dystroglycan and Heparan sulfate proteoglycans, we discuss a possible function of glycoproteins in draxin/netrin-1-mediated axon guidance.
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Affiliation(s)
- Giasuddin Ahmed
- Department of Neuroscience and Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Yohei Shinmyo
- Department of Medical Neuroscience, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
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15
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Abstract
[Figure: see text].
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Affiliation(s)
- Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
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16
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Malheiro A, Wieringa P, Moroni L. Peripheral neurovascular link: an overview of interactions and in vitro models. Trends Endocrinol Metab 2021; 32:623-638. [PMID: 34127366 DOI: 10.1016/j.tem.2021.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 04/23/2021] [Accepted: 05/10/2021] [Indexed: 12/26/2022]
Abstract
Nerves and blood vessels (BVs) establish extensive arborized networks to innervate tissues and deliver oxygen/metabolic support. Developmental cues direct the formation of these intricate and often overlapping patterns, which reflect close interactions within the peripheral neurovascular system. Besides the mutual dependence to survive and function, nerves and BVs share several receptors and ligands, as well as principles of differentiation, growth and pathfinding. Neurovascular (NV) interactions are maintained in adult life and are essential for certain regenerative mechanisms, such as wound healing. In pathological situations (e.g., type 2 diabetes mellitus), the NV system can be severely perturbed and become dysfunctional. Unwanted neural growth and vascularization are also associated with the progression of some pathologies, such as cancer and endometriosis. In this review, we describe the fundamental NV interactions in development, highlighting the similarities between both networks and wiring mechanisms. We also describe the NV contribution to regenerative processes and potential pathological dysfunctions. Finally, we provide an overview of current in vitro models used to replicate and investigate the NV ecosystem, addressing present limitations and future perspectives.
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Affiliation(s)
- Afonso Malheiro
- Complex Tissue Regeneration Department, MERLN Institute for Technology-Inspired Regenerative Medicine, Universiteitssingel 40, 6229ER Maastricht, The Netherlands
| | - Paul Wieringa
- Complex Tissue Regeneration Department, MERLN Institute for Technology-Inspired Regenerative Medicine, Universiteitssingel 40, 6229ER Maastricht, The Netherlands
| | - Lorenzo Moroni
- Complex Tissue Regeneration Department, MERLN Institute for Technology-Inspired Regenerative Medicine, Universiteitssingel 40, 6229ER Maastricht, The Netherlands.
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17
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Baier H. Friedrich Bonhoeffer (1932–2021). Neuron 2021. [DOI: 10.1016/j.neuron.2021.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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Drescher U. Obituary: Friedrich Bonhoeffer (1932-2021). Development 2021. [PMID: 33632717 DOI: 10.1242/dev.199522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary: Uwe Drescher commemorates the life and work of Friedrich Bonhoeffer, whose pioneering work – including the development of innovative in vitro assays – led to important discoveries in the field of axon guidance and neural development.
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Affiliation(s)
- Uwe Drescher
- Centre for Developmental Neurobiology, MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK
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19
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O'Hara-Wright M, Gonzalez-Cordero A. Retinal organoids: a window into human retinal development. Development 2020; 147:147/24/dev189746. [PMID: 33361444 PMCID: PMC7774906 DOI: 10.1242/dev.189746] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Retinal development and maturation are orchestrated by a series of interacting signalling networks that drive the morphogenetic transformation of the anterior developing brain. Studies in model organisms continue to elucidate these complex series of events. However, the human retina shows many differences from that of other organisms and the investigation of human eye development now benefits from stem cell-derived organoids. Retinal differentiation methods have progressed from simple 2D adherent cultures to self-organising micro-physiological systems. As models of development, these have collectively offered new insights into the previously unexplored early development of the human retina and informed our knowledge of the key cell fate decisions that govern the specification of light-sensitive photoreceptors. Although the developmental trajectories of other retinal cell types remain more elusive, the collation of omics datasets, combined with advanced culture methodology, will enable modelling of the intricate process of human retinogenesis and retinal disease in vitro. Summary: Retinal organoid systems derived from human pluripotent stem cells are micro-physiological systems that offer new insights into previously unexplored human retina development.
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Affiliation(s)
- Michelle O'Hara-Wright
- Stem Cell Medicine Group, Children's Medical Research Institute, University of Sydney, Westmead, 2145, NSW, Australia.,School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Westmead, 2145, NSW, Australia
| | - Anai Gonzalez-Cordero
- Stem Cell Medicine Group, Children's Medical Research Institute, University of Sydney, Westmead, 2145, NSW, Australia .,School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Westmead, 2145, NSW, Australia
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20
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Leonard CE, Baydyuk M, Stepler MA, Burton DA, Donoghue MJ. EphA7 isoforms differentially regulate cortical dendrite development. PLoS One 2020; 15:e0231561. [PMID: 33275600 PMCID: PMC7717530 DOI: 10.1371/journal.pone.0231561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 11/22/2020] [Indexed: 02/06/2023] Open
Abstract
The shape of a neuron facilitates its functionality within neural circuits. Dendrites integrate incoming signals from axons, receiving excitatory input onto small protrusions called dendritic spines. Therefore, understanding dendritic growth and development is fundamental for discerning neural function. We previously demonstrated that EphA7 receptor signaling during cortical development impacts dendrites in two ways: EphA7 restricts dendritic growth early and promotes dendritic spine formation later. Here, the molecular basis for this shift in EphA7 function is defined. Expression analyses reveal that EphA7 full-length (EphA7-FL) and truncated (EphA7-T1; lacking kinase domain) isoforms are dynamically expressed in the developing cortex. Peak expression of EphA7-FL overlaps with dendritic elaboration around birth, while highest expression of EphA7-T1 coincides with dendritic spine formation in early postnatal life. Overexpression studies in cultured neurons demonstrate that EphA7-FL inhibits both dendritic growth and spine formation, while EphA7-T1 increases spine density. Furthermore, signaling downstream of EphA7 shifts during development, such that in vivo inhibition of mTOR by rapamycin in EphA7-mutant neurons ameliorates dendritic branching, but not dendritic spine phenotypes. Finally, direct interaction between EphA7-FL and EphA7-T1 is demonstrated in cultured cells, which results in reduction of EphA7-FL phosphorylation. In cortex, both isoforms are colocalized to synaptic fractions and both transcripts are expressed together within individual neurons, supporting a model where EphA7-T1 modulates EphA7-FL repulsive signaling during development. Thus, the divergent functions of EphA7 during cortical dendrite development are explained by the presence of two variants of the receptor.
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Affiliation(s)
- Carrie E. Leonard
- Department of Biology, Georgetown University, Washington, DC, United States of America
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States of America
| | - Maryna Baydyuk
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Marissa A. Stepler
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Denver A. Burton
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Maria J. Donoghue
- Department of Biology, Georgetown University, Washington, DC, United States of America
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States of America
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21
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das Neves SP, Sousa JC, Sousa N, Cerqueira JJ, Marques F. Altered astrocytic function in experimental neuroinflammation and multiple sclerosis. Glia 2020; 69:1341-1368. [PMID: 33247866 DOI: 10.1002/glia.23940] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/14/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022]
Abstract
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) that affects about 2.5 million people worldwide. In MS, the patients' immune system starts to attack the myelin sheath, leading to demyelination, neurodegeneration, and, ultimately, loss of vital neurological functions such as walking. There is currently no cure for MS and the available treatments only slow the initial phases of the disease. The later-disease mechanisms are poorly understood and do not directly correlate with the activity of immune system cells, the main target of the available treatments. Instead, evidence suggests that disease progression and disability are better correlated with the maintenance of a persistent low-grade inflammation inside the CNS, driven by local glial cells, like astrocytes and microglia. Depending on the context, astrocytes can (a) exacerbate inflammation or (b) promote immunosuppression and tissue repair. In this review, we will address the present knowledge that exists regarding the role of astrocytes in MS and experimental animal models of the disease.
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Affiliation(s)
- Sofia Pereira das Neves
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga, Portugal
| | - João Carlos Sousa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga, Portugal.,Clinical Academic Center, Braga, Portugal
| | - João José Cerqueira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga, Portugal.,Clinical Academic Center, Braga, Portugal
| | - Fernanda Marques
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga, Portugal
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22
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Johnson KO, Triplett JW. Wiring subcortical image-forming centers: Topography, laminar targeting, and map alignment. Curr Top Dev Biol 2020; 142:283-317. [PMID: 33706920 DOI: 10.1016/bs.ctdb.2020.10.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Efficient sensory processing is a complex and important function for species survival. As such, sensory circuits are highly organized to facilitate rapid detection of salient stimuli and initiate motor responses. For decades, the retina's projections to image-forming centers have served as useful models to elucidate the mechanisms by which such exquisite circuitry is wired. In this chapter, we review the roles of molecular cues, neuronal activity, and axon-axon competition in the development of topographically ordered retinal ganglion cell (RGC) projections to the superior colliculus (SC) and dorsal lateral geniculate nucleus (dLGN). Further, we discuss our current state of understanding regarding the laminar-specific targeting of subclasses of RGCs in the SC and its homolog, the optic tectum (OT). Finally, we cover recent studies examining the alignment of projections from primary visual cortex with RGCs that monitor the same region of space in the SC.
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Affiliation(s)
- Kristy O Johnson
- Center for Neuroscience Research, Children's National Research Institute, Washington, DC, United States; Institute for Biomedical Sciences, The George Washington University School of Medicine, Washington, DC, United States
| | - Jason W Triplett
- Center for Neuroscience Research, Children's National Research Institute, Washington, DC, United States; Department of Pediatrics, The George Washington University School of Medicine, Washington, DC, United States.
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23
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Hiesinger PR. Brain wiring with composite instructions. Bioessays 2020; 43:e2000166. [PMID: 33145823 DOI: 10.1002/bies.202000166] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/27/2020] [Accepted: 09/29/2020] [Indexed: 11/12/2022]
Abstract
The quest for molecular mechanisms that guide axons or specify synaptic contacts has largely focused on molecules that intuitively relate to the idea of an "instruction." By contrast, "permissive" factors are traditionally considered background machinery without contribution to the information content of a molecularly executed instruction. In this essay, I recast this dichotomy as a continuum from permissive to instructive actions of single factors that provide relative contributions to a necessarily collaborative effort. Individual molecules or other factors do not constitute absolute instructions by themselves; they provide necessary context for each other, thereby creating a composite that defines the overall instruction. The idea of composite instructions leads to two main conclusions: first, a composite of many seemingly permissive factors can define a specific instruction even in the absence of a single dominant contributor; second, individual factors are not necessarily related intuitively to the overall instruction or phenotypic outcome.
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Affiliation(s)
- P Robin Hiesinger
- Division of Neurobiology, Institute for Biology, Freie Universität Berlin, Berlin, Germany
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24
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Context-Dependent Role of miR-124 in Retinoic Acid-Induced Growth Cone Attraction of Regenerating Motorneurons. Cell Mol Neurobiol 2020; 42:847-869. [PMID: 33094464 DOI: 10.1007/s10571-020-00982-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/14/2020] [Indexed: 10/23/2022]
Abstract
During development and regeneration, growth cones at the tips of extending axons navigate through a complex environment to establish accurate connections with appropriate targets. Growth cones can respond rapidly to classical and non-classical guidance cues in their environment, often requiring local protein synthesis. In vertebrate growth cones, local protein synthesis in response to classical cues can require regulation by microRNAs (miRNAs), a class of small, conserved, non-coding RNAs that post-transcriptionally regulate gene expression. However, less is known of how miRNAs mediate growth cone responses to non-classical cues (such as retinoic acid (RA)), specifically in invertebrates. Here, we utilized adult regenerating invertebrate motorneurons to study miRNA regulation of growth cone attraction to RA, shown to require local protein synthesis. In situ hybridization revealed the presence of miR-124 in growth cones of regenerating ciliary motorneurons of the mollusc Lymnaea stagnalis. Changes in the spatiotemporal distribution of miR-124 occurred following application of RA, and dysregulation of miR-124 (with mimic injection), disrupted RA-induced growth cone turning in a time-dependent manner. This behavioural regulation by miR-124 was altered when the neurite was transected, and the growth cone completely separated from the soma. miR-124 did not, however, appear to be involved in growth cone attraction to serotonin, a response independent of local protein synthesis. Finally, we provide evidence that a downstream effector of RhoGTPases, ROCK, is a potential target of miR-124 during RA-induced growth cone responses. These data advance our current understanding of how microRNAs might mediate cue- and context-dependent behaviours during axon guidance.
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25
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Arcas A, Wilkinson DG, Nieto MÁ. The Evolutionary History of Ephs and Ephrins: Toward Multicellular Organisms. Mol Biol Evol 2020; 37:379-394. [PMID: 31589243 PMCID: PMC6993872 DOI: 10.1093/molbev/msz222] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Eph receptor (Eph) and ephrin signaling regulate fundamental developmental processes through both forward and reverse signaling triggered upon cell–cell contact. In vertebrates, they are both classified into classes A and B, and some representatives have been identified in many metazoan groups, where their expression and functions have been well studied. We have extended previous phylogenetic analyses and examined the presence of Eph and ephrins in the tree of life to determine their origin and evolution. We have found that 1) premetazoan choanoflagellates may already have rudimental Eph/ephrin signaling as they have an Eph-/ephrin-like pair and homologs of downstream-signaling genes; 2) both forward- and reverse-downstream signaling might already occur in Porifera since sponges have most genes involved in these types of signaling; 3) the nonvertebrate metazoan Eph is a type-B receptor that can bind ephrins regardless of their membrane-anchoring structure, glycosylphosphatidylinositol, or transmembrane; 4) Eph/ephrin cross-class binding is specific to Gnathostomata; and 5) kinase-dead Eph receptors can be traced back to Gnathostomata. We conclude that Eph/ephrin signaling is of older origin than previously believed. We also examined the presence of protein domains associated with functional characteristics and the appearance and conservation of downstream-signaling pathways to understand the original and derived functions of Ephs and ephrins. We find that the evolutionary history of these gene families points to an ancestral function in cell–cell interactions that could contribute to the emergence of multicellularity and, in particular, to the required segregation of cell populations.
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Affiliation(s)
- Aida Arcas
- Instituto de Neurociencias (CSIC-UMH), Avda, San Juan de Alicante, Spain
| | - David G Wilkinson
- Neural Development Laboratory, The Francis Crick Institute, London, United Kingdom
| | - M Ángela Nieto
- Instituto de Neurociencias (CSIC-UMH), Avda, San Juan de Alicante, Spain
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26
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Harada H, Charish J, Monnier PP. Emerging evidence for cell-autonomous axon guidance. Dev Growth Differ 2020; 62:391-397. [PMID: 32279322 DOI: 10.1111/dgd.12666] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 03/31/2020] [Accepted: 04/03/2020] [Indexed: 11/28/2022]
Abstract
Current models of axon guidance within the central nervous system (CNS) involve the presentation of environmental cues to navigating growth cones. The surrounding and target tissues present a variety of ligands that either restrict or promote growth, thus providing pathfinding instructions to developing axons. Recent findings show that RGMb, a GPI anchored extracellular protein present on retinal ganglion cells, down-regulates Wnt3a signaling by lowering LRP5 levels at the membrane surface. When RGMb is phosphorylated by the extracellular tyrosine kinase VLK, phosphorylated RGMb (p-RGMb) is internalized and carries LRP5 towards intracellular compartments. In the eye, a dorsal-high ventral-low gradient of VLK generates a dorsal-low ventral-high gradient of LRP5 that modulates Wnt3a signaling. These molecules, which are all expressed by individual RGCs, generate Wnt-signal gradients along the dorso-ventral axis of the retina, resulting in differential axon growth which in turn regulates proper retino-tectal/collicular map formation. This pathway represents a regulatory mechanism whereby extracellular phosphorylation generates what may be the first example of a unique self-guiding mechanism that affects neuronal-target connections independent of paracrine signals from the surrounding target tissue.
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Affiliation(s)
- Hidekiyo Harada
- Vision Division, Krembil Research Institute, Krembil Discovery Tower, Toronto, Ontario, Canada
| | - Jason Charish
- Vision Division, Krembil Research Institute, Krembil Discovery Tower, Toronto, Ontario, Canada
| | - Philippe P Monnier
- Vision Division, Krembil Research Institute, Krembil Discovery Tower, Toronto, Ontario, Canada.,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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27
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Sanes JR, Zipursky SL. Synaptic Specificity, Recognition Molecules, and Assembly of Neural Circuits. Cell 2020; 181:536-556. [DOI: 10.1016/j.cell.2020.04.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/23/2020] [Accepted: 04/06/2020] [Indexed: 01/02/2023]
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28
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Lackey EP, Sillitoe RV. Eph/ephrin Function Contributes to the Patterning of Spinocerebellar Mossy Fibers Into Parasagittal Zones. Front Syst Neurosci 2020; 14:7. [PMID: 32116578 PMCID: PMC7033604 DOI: 10.3389/fnsys.2020.00007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 01/24/2020] [Indexed: 12/14/2022] Open
Abstract
Purkinje cell microcircuits perform diverse functions using widespread inputs from the brain and spinal cord. The formation of these functional circuits depends on developmental programs and molecular pathways that organize mossy fiber afferents from different sources into a complex and precisely patterned map within the granular layer of the cerebellum. During development, Purkinje cell zonal patterns are thought to guide mossy fiber terminals into zones. However, the molecular mechanisms that mediate this process remain unclear. Here, we used knockout mice to test whether Eph/ephrin signaling controls Purkinje cell-mossy fiber interactions during cerebellar circuit formation. Loss of ephrin-A2 and ephrin-A5 disrupted the patterning of spinocerebellar terminals into discrete zones. Zone territories in the granular layer that normally have limited spinocerebellar input contained ectopic terminals in ephrin-A2 -/-;ephrin-A5 -/- double knockout mice. However, the overall morphology of the cerebellum, lobule position, and Purkinje cell zonal patterns developed normally in the ephrin-A2 -/-;ephrin-A5 -/- mutant mice. This work suggests that communication between Purkinje cell zones and mossy fibers during postnatal development allows contact-dependent molecular cues to sharpen the innervation of sensory afferents into functional zones.
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Affiliation(s)
- Elizabeth P Lackey
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, United States
| | - Roy V Sillitoe
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, United States.,Development, Disease Models & Therapeutics Graduate Program, Baylor College of Medicine, Houston, TX, United States.,Developmental Biology Graduate Program, Baylor College of Medicine, Houston, TX, United States
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29
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Medori M, Spelzini G, Scicolone G. Molecular complexity of visual mapping: a challenge for regenerating therapy. Neural Regen Res 2020; 15:382-389. [PMID: 31571645 PMCID: PMC6921353 DOI: 10.4103/1673-5374.266044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Investigating the cellular and molecular mechanisms involved in the development of topographically ordered connections in the central nervous system constitutes an important issue in neurobiology because these connections are the base of the central nervous system normal function. The dominant model to study the development of topographic maps is the projection from the retinal ganglion cells to the optic tectum/colliculus. The expression pattern of Eph/ephrin system in opposing gradients both in the retina and the tectum, labels the local addresses on the target and gives specific sensitivities to growth cones according to their topographic origin in the retina. The rigid precision of normal retinotopic mapping has prompted the chemoaffinity hypothesis, positing axonal targeting to be based on fixed biochemical affinities between fibers and targets. However, several lines of evidence have shown that the mapping can adjust to experimentally modified targets with flexibility, demonstrating the robustness of the guidance process. Here we discuss the complex ways the Ephs and ephrins interact allowing to understand how the retinotectal mapping is a precise but also a flexible process.
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Affiliation(s)
- Mara Medori
- CONICET - Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis" (IBCN); Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina
| | - Gonzalo Spelzini
- CONICET - Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis" (IBCN); Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina
| | - Gabriel Scicolone
- CONICET - Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis" (IBCN); Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina
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30
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Harada H, Farhani N, Wang XF, Sugita S, Charish J, Attisano L, Moran M, Cloutier JF, Reber M, Bremner R, Monnier PP. Extracellular phosphorylation drives the formation of neuronal circuitry. Nat Chem Biol 2019; 15:1035-1042. [PMID: 31451763 DOI: 10.1038/s41589-019-0345-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 07/14/2019] [Indexed: 12/29/2022]
Abstract
Until recently, the existence of extracellular kinase activity was questioned. Many proteins of the central nervous system are targeted, but it remains unknown whether, or how, extracellular phosphorylation influences brain development. Here we show that the tyrosine kinase vertebrate lonesome kinase (VLK), which is secreted by projecting retinal ganglion cells, phosphorylates the extracellular protein repulsive guidance molecule b (RGMb) in a dorsal-ventral descending gradient. Silencing of VLK or RGMb causes aberrant axonal branching and severe axon misguidance in the chick optic tectum. Mice harboring RGMb with a point mutation in the phosphorylation site also display aberrant axonal pathfinding. Mechanistic analyses show that VLK-mediated RGMb phosphorylation modulates Wnt3a activity by regulating LRP5 protein gradients. Thus, the secretion of VLK by projecting neurons provides crucial signals for the accurate formation of nervous system circuitry. The dramatic effect of VLK on RGMb and Wnt3a signaling implies that extracellular phosphorylation likely has broad and profound effects on brain development, function and disease.
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Affiliation(s)
- Hidekiyo Harada
- Krembil Research Institute, Vision Division, Krembil Discovery Tower, Toronto, Ontario, Canada
| | - Nahal Farhani
- Krembil Research Institute, Vision Division, Krembil Discovery Tower, Toronto, Ontario, Canada
| | - Xue-Fan Wang
- Krembil Research Institute, Vision Division, Krembil Discovery Tower, Toronto, Ontario, Canada
| | - Shuzo Sugita
- Krembil Research Institute, Vision Division, Krembil Discovery Tower, Toronto, Ontario, Canada
| | - Jason Charish
- Krembil Research Institute, Vision Division, Krembil Discovery Tower, Toronto, Ontario, Canada.,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Liliana Attisano
- Department of Biochemistry, Donnelly Center, University of Toronto, Toronto, Ontario, Canada
| | - Michael Moran
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | | | - Michael Reber
- Krembil Research Institute, Vision Division, Krembil Discovery Tower, Toronto, Ontario, Canada.,Department of Ophthalmology and Vision Sciences, Faculty of Medicine, University of Toronto, Ontario, Toronto, Canada.,CNRS UPR3212, University of Strasbourg, Strasbourg, France
| | - Rod Bremner
- Lunenfeld Tannenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Philippe P Monnier
- Krembil Research Institute, Vision Division, Krembil Discovery Tower, Toronto, Ontario, Canada. .,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada. .,Department of Ophthalmology and Vision Sciences, Faculty of Medicine, University of Toronto, Ontario, Toronto, Canada.
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31
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Rué L, Oeckl P, Timmers M, Lenaerts A, van der Vos J, Smolders S, Poppe L, de Boer A, Van Den Bosch L, Van Damme P, Weishaupt JH, Ludolph AC, Otto M, Robberecht W, Lemmens R. Reduction of ephrin-A5 aggravates disease progression in amyotrophic lateral sclerosis. Acta Neuropathol Commun 2019; 7:114. [PMID: 31300041 PMCID: PMC6626434 DOI: 10.1186/s40478-019-0759-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 06/22/2019] [Indexed: 12/30/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that affects motor neurons in the brainstem, spinal cord and motor cortex. ALS is characterized by genetic and clinical heterogeneity, suggesting the existence of genetic factors that modify the phenotypic expression of the disease. We previously identified the axonal guidance EphA4 receptor, member of the Eph-ephrin system, as an ALS disease-modifying factor. EphA4 genetic inhibition rescued the motor neuron phenotype in zebrafish and a rodent model of ALS. Preventing ligands from binding to the EphA4 receptor also successfully improved disease, suggesting a role for EphA4 ligands in ALS. One particular ligand, ephrin-A5, is upregulated in reactive astrocytes after acute neuronal injury and inhibits axonal regeneration. Moreover, it plays a role during development in the correct pathfinding of motor axons towards their target limb muscles. We hypothesized that a constitutive reduction of ephrin-A5 signalling would benefit disease progression in a rodent model for ALS. We discovered that in the spinal cord of control and symptomatic ALS mice ephrin-A5 was predominantly expressed in neurons. Surprisingly, reduction of ephrin-A5 levels in SOD1G93A mice accelerated disease progression and reduced survival without affecting disease onset, motor neuron numbers or innervated neuromuscular junctions in symptomatic mice. These findings suggest ephrin-A5 as a modifier of disease progression that might play a role in the later stages of the disease. Similarly, we identified a more aggressive disease progression in patients with lower ephrin-A5 protein levels in the cerebrospinal fluid without modifying disease onset. In summary, we identified reduced expression of ephrin-A5 to accelerate disease progression in a mouse model of ALS as well as in humans. Combined with our previous findings on the role of EphA4 in ALS our current data suggests different contribution for various members of the Eph-ephrin system in the pathophysiology of a motor neuron disease.
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32
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Murcia-Belmonte V, Erskine L. Wiring the Binocular Visual Pathways. Int J Mol Sci 2019; 20:ijms20133282. [PMID: 31277365 PMCID: PMC6651880 DOI: 10.3390/ijms20133282] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 06/29/2019] [Accepted: 07/03/2019] [Indexed: 02/06/2023] Open
Abstract
Retinal ganglion cells (RGCs) extend axons out of the retina to transmit visual information to the brain. These connections are established during development through the navigation of RGC axons along a relatively long, stereotypical pathway. RGC axons exit the eye at the optic disc and extend along the optic nerves to the ventral midline of the brain, where the two nerves meet to form the optic chiasm. In animals with binocular vision, the axons face a choice at the optic chiasm—to cross the midline and project to targets on the contralateral side of the brain, or avoid crossing the midline and project to ipsilateral brain targets. Ipsilaterally and contralaterally projecting RGCs originate in disparate regions of the retina that relate to the extent of binocular overlap in the visual field. In humans virtually all RGC axons originating in temporal retina project ipsilaterally, whereas in mice, ipsilaterally projecting RGCs are confined to the peripheral ventrotemporal retina. This review will discuss recent advances in our understanding of the mechanisms regulating specification of ipsilateral versus contralateral RGCs, and the differential guidance of their axons at the optic chiasm. Recent insights into the establishment of congruent topographic maps in both brain hemispheres also will be discussed.
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Affiliation(s)
| | - Lynda Erskine
- School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland AB25 2ZD, UK
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Niftullayev S, Lamarche-Vane N. Regulators of Rho GTPases in the Nervous System: Molecular Implication in Axon Guidance and Neurological Disorders. Int J Mol Sci 2019; 20:E1497. [PMID: 30934641 PMCID: PMC6471118 DOI: 10.3390/ijms20061497] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 03/18/2019] [Indexed: 12/11/2022] Open
Abstract
One of the fundamental steps during development of the nervous system is the formation of proper connections between neurons and their target cells-a process called neural wiring, failure of which causes neurological disorders ranging from autism to Down's syndrome. Axons navigate through the complex environment of a developing embryo toward their targets, which can be far away from their cell bodies. Successful implementation of neuronal wiring, which is crucial for fulfillment of all behavioral functions, is achieved through an intimate interplay between axon guidance and neural activity. In this review, our focus will be on axon pathfinding and the implication of some of its downstream molecular components in neurological disorders. More precisely, we will talk about axon guidance and the molecules implicated in this process. After, we will briefly review the Rho family of small GTPases, their regulators, and their involvement in downstream signaling pathways of the axon guidance cues/receptor complexes. We will then proceed to the final and main part of this review, where we will thoroughly comment on the implication of the regulators for Rho GTPases-GEFs (Guanine nucleotide Exchange Factors) and GAPs (GTPase-activating Proteins)-in neurological diseases and disorders.
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Affiliation(s)
- Sadig Niftullayev
- Cancer Research Program, Research Institute of the MUHC, Montreal, QC H4A 3J1, Canada.
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 2B2, Canada.
| | - Nathalie Lamarche-Vane
- Cancer Research Program, Research Institute of the MUHC, Montreal, QC H4A 3J1, Canada.
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 2B2, Canada.
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Coordination of neural patterning in the Drosophila visual system. Curr Opin Neurobiol 2019; 56:153-159. [PMID: 30849690 DOI: 10.1016/j.conb.2019.01.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 01/30/2019] [Indexed: 01/07/2023]
Abstract
Precise formation of neuronal circuits requires the coordinated development of the different components of the circuit. Here, we review examples of coordination at multiples scales of development in one of the best-studied systems for neural patterning and circuit assembly, the Drosophila visual system, from coordination of gene expression in photoreceptors to the coordinated patterning of the different neuropiles of the optic lobe.
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Cheng Q, Graves MD, Pallas SL. Dynamic Alterations of Retinal EphA5 Expression in Retinocollicular Map Plasticity. Dev Neurobiol 2019; 79:252-267. [PMID: 30916472 PMCID: PMC6506164 DOI: 10.1002/dneu.22675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 02/14/2019] [Accepted: 02/28/2019] [Indexed: 11/10/2022]
Abstract
The topographically ordered retinocollicular projection is an excellent system for studying the mechanism of axon guidance. Gradients of EphA receptors in the retina and ephrin-As in the superior colliculus (SC) pattern the anteroposterior axis of the retinocollicular map, but whether they are involved in map plasticity after injury is unknown. Partial damage to the caudal SC at birth creates a compressed, complete retinotopic map in the remaining SC without affecting visual response properties. Previously, we found that the gradient of ephrin-A expression in compressed maps is steeper than normal, suggesting an instructive role in compression. Here we measured EphA5 mRNA and protein levels after caudal SC damage in order to test the hypothesis that changes in retinal EphA5 expression occur that are complementary to the changes in collicular ephrin-A expression. We find that the nasotemporal gradient of EphA5 receptor expression steepens in the retina and overall expression levels change dynamically, especially in temporal retina, supporting the hypothesis. This change in receptor expression occurs after the change in ephrin-A ligand expression. We propose that changes in the retinal EphA5 gradient guide recovery of the retinocollicular projection from early injury. This could occur directly through the change in EphA5 expression instructing retino-SC map compression, or through ephrin-A ligand signaling instructing a change in EphA5 receptor expression that in turn signals the retinocollicular map to compress. Understanding what molecular signals direct compensation for injury is essential to developing rehabilitative strategies and maximizing the potential for recovery.
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Affiliation(s)
- Qi Cheng
- Neuroscience Institute Georgia State University, Atlanta, GA, USA
| | - Mark D. Graves
- Department of Biology, Georgia State University, Atlanta, GA, USA
| | - Sarah L. Pallas
- Neuroscience Institute Georgia State University, Atlanta, GA, USA
- Department of Biology, Georgia State University, Atlanta, GA, USA
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Nakamoto C, Durward E, Horie M, Nakamoto M. Nell2 regulates the contralateral-versus-ipsilateral visual projection as a domain-specific positional cue. Development 2019; 146:dev.170704. [PMID: 30745429 DOI: 10.1242/dev.170704] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 01/29/2019] [Indexed: 01/15/2023]
Abstract
In mammals with binocular vision, retinal ganglion cell (RGC) axons from each eye project to eye-specific domains in the contralateral and ipsilateral dorsal lateral geniculate nucleus (dLGN), underpinning disparity-based stereopsis. Although domain-specific axon guidance cues that discriminate contralateral and ipsilateral RGC axons have long been postulated as a key mechanism for development of the eye-specific retinogeniculate projection, the molecular nature of such cues has remained elusive. Here, we show that the extracellular glycoprotein Nell2 (neural epidermal growth factor-like-like 2) is expressed in the dorsomedial region of the dLGN, which ipsilateral RGC axons terminate in and contralateral axons avoid. In Nell2 mutant mice, contralateral RGC axons abnormally invaded the ipsilateral domain of the dLGN, and ipsilateral axons terminated in partially fragmented patches, forming a mosaic pattern of contralateral and ipsilateral axon-termination zones. In vitro, Nell2 exerted inhibitory effects on contralateral, but not ipsilateral, RGC axons. These results provide evidence that Nell2 acts as a domain-specific positional label in the dLGN that discriminates contralateral and ipsilateral RGC axons, and that it plays essential roles in the establishment of the eye-specific retinogeniculate projection.
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Affiliation(s)
- Chizu Nakamoto
- Aberdeen Developmental Biology Group, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Elaine Durward
- Aberdeen Developmental Biology Group, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Masato Horie
- Department of CNS Research, Otsuka Pharmaceutical, 463-10 Kagasuno, Kawauchi-cho, Tokushima 771-0192, Japan
| | - Masaru Nakamoto
- Aberdeen Developmental Biology Group, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
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Regulation of axonal EphA4 forward signaling is involved in the effect of EphA3 on chicken retinal ganglion cell axon growth during retinotectal mapping. Exp Eye Res 2019; 178:46-60. [DOI: 10.1016/j.exer.2018.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 09/06/2018] [Accepted: 09/16/2018] [Indexed: 12/22/2022]
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Chang CJ, Chang MY, Lee YC, Chen KY, Hsu TI, Wu YH, Chuang JY, Kao TJ. Nck2 is essential for limb trajectory selection by spinal motor axons. Dev Dyn 2018; 247:1043-1056. [DOI: 10.1002/dvdy.24656] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 07/02/2018] [Accepted: 07/03/2018] [Indexed: 11/08/2022] Open
Affiliation(s)
- Chih-Ju Chang
- Department of Neurosurgery; Cathay General Hospital; Taipei Taiwan
- School of Medicine; Fu Jen Catholic University; New Taipei Taiwan
- Departemnt of Mechanical Engineering; National Central University; Taiwan
| | - Ming-Yuan Chang
- Division of Neurosurgery, Department of Surgery; Min-Sheng General Hospital; Taiwan
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology; Taipei Medical University; Taipei Taiwan
| | - Yi-Chao Lee
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology; Taipei Medical University; Taipei Taiwan
- Center for Neurotrauma and Neuroregeneration; Taipei Medical University; Taipei Taiwan
| | - Kai-Yun Chen
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology; Taipei Medical University; Taipei Taiwan
- Center for Neurotrauma and Neuroregeneration; Taipei Medical University; Taipei Taiwan
| | - Tsung-I Hsu
- Center for Neurotrauma and Neuroregeneration; Taipei Medical University; Taipei Taiwan
| | - Yi-Hsin Wu
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology; Taipei Medical University; Taipei Taiwan
- Center for Neurotrauma and Neuroregeneration; Taipei Medical University; Taipei Taiwan
| | - Jian-Ying Chuang
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology; Taipei Medical University; Taipei Taiwan
- Center for Neurotrauma and Neuroregeneration; Taipei Medical University; Taipei Taiwan
| | - Tzu-Jen Kao
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology; Taipei Medical University; Taipei Taiwan
- Center for Neurotrauma and Neuroregeneration; Taipei Medical University; Taipei Taiwan
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Sardana J, Organisti C, Grunwald Kadow IC. Eph Receptor Effector Ephexin Mediates Olfactory Dendrite Targeting in Drosophila. Dev Neurobiol 2018; 78:873-888. [PMID: 30019861 DOI: 10.1002/dneu.22624] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/12/2018] [Accepted: 06/13/2018] [Indexed: 11/08/2022]
Abstract
Deciphering the mechanisms of sensory neural map formation is a central aim in neurosciences. Failure to form a correct map frequently leads to defects in sensory processing and perception. The olfactory map develops in subsequent steps initially forming a rough and later a precise map of glomeruli in the antennal lobe (AL), mainly consisting of olfactory receptor neuron (ORN) axons and projection neuron (PN) dendrites. The mechanisms underpinning the later stage of class-specific glomerulus formation are not understood. Recent studies have shown that the important guidance molecule Eph and its ligand ephrin play a role in class-specific PN targeting. Here, we reveal aspects of the mechanism downstream of Eph signaling during olfactory map formation. We show that the Eph-specific RhoGEF Ephexin (Exn) is required to fine tune PN dendrite patterning within specific glomeruli. We provide the first report showing an in vivo neurite guidance defect in an exn mutant. Interestingly, the quality of the phenotypes is different between eph and exn mutants; while loss of Eph leads to strong misprojections of DM3/Or47a neurons along the medial-lateral axis of the antennal lobe (AL), loss of Exn induces ventral ectopic innervation of a neighboring glomerulus. Genetic interaction experiments suggest that differential signaling of the small GTPases Rac1 and Cdc42 mediated by Exn-dependent and -independent Eph signaling fine tunes spatial targeting of PN dendrites within the olfactory map. We propose that their distinct activities on the actin cytoskeleton are required for precise navigation of PN dendrites within the olfactory map. Taken together, our results suggest that the precise connectivity of an individual neuron can depend on different modes of signaling downstream of a single guidance receptor. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 00: 000-000, 2018.
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Affiliation(s)
- Juhi Sardana
- Max Planck Institute of Neurobiology, Chemosensory Coding Research Group, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Cristina Organisti
- Max Planck Institute of Neurobiology, Chemosensory Coding Research Group, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Ilona C Grunwald Kadow
- Max Planck Institute of Neurobiology, Chemosensory Coding Research Group, Am Klopferspitz 18, Martinsried 82152, Germany.,Technical University Munich, School of Life Sciences, Liesel-Beckmann Str. 4, Freising 85354, Germany
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40
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Abstract
The cadherin superfamily comprises a large, diverse collection of cell surface receptors that are expressed in the nervous system throughout development and have been shown to be essential for the proper assembly of the vertebrate nervous system. As our knowledge of each family member has grown, it has become increasingly clear that the functions of various cadherin subfamilies are intertwined: they can be present in the same protein complexes, impinge on the same developmental processes, and influence the same signaling pathways. This interconnectedness may illustrate a central way in which core developmental events are controlled to bring about the robust and precise assembly of neural circuitry.
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Affiliation(s)
- James D Jontes
- Department of Neuroscience, Ohio State University, Ohio 43210
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41
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Sarin S, Zuniga-Sanchez E, Kurmangaliyev YZ, Cousins H, Patel M, Hernandez J, Zhang KX, Samuel MA, Morey M, Sanes JR, Zipursky SL. Role for Wnt Signaling in Retinal Neuropil Development: Analysis via RNA-Seq and In Vivo Somatic CRISPR Mutagenesis. Neuron 2018; 98:109-126.e8. [PMID: 29576390 DOI: 10.1016/j.neuron.2018.03.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 01/16/2018] [Accepted: 03/02/2018] [Indexed: 12/22/2022]
Abstract
Screens for genes that orchestrate neural circuit formation in mammals have been hindered by practical constraints of germline mutagenesis. To overcome these limitations, we combined RNA-seq with somatic CRISPR mutagenesis to study synapse development in the mouse retina. Here synapses occur between cellular layers, forming two multilayered neuropils. The outer neuropil, the outer plexiform layer (OPL), contains synapses made by rod and cone photoreceptor axons on rod and cone bipolar dendrites, respectively. We used RNA-seq to identify selectively expressed genes encoding cell surface and secreted proteins and CRISPR-Cas9 electroporation with cell-specific promoters to assess their roles in OPL development. Among the genes identified in this way are Wnt5a and Wnt5b. They are produced by rod bipolars and activate a non-canonical signaling pathway in rods to regulate early OPL patterning. The approach we use here can be applied to other parts of the brain.
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Affiliation(s)
- Sumeet Sarin
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA
| | - Elizabeth Zuniga-Sanchez
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yerbol Z Kurmangaliyev
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Henry Cousins
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA
| | - Mili Patel
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA
| | - Jeanette Hernandez
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kelvin X Zhang
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Melanie A Samuel
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA
| | - Marta Morey
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Joshua R Sanes
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA.
| | - S Lawrence Zipursky
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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Hornix BE, Havekes R, Kas MJH. Multisensory cortical processing and dysfunction across the neuropsychiatric spectrum. Neurosci Biobehav Rev 2018; 97:138-151. [PMID: 29496479 DOI: 10.1016/j.neubiorev.2018.02.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 02/12/2018] [Accepted: 02/13/2018] [Indexed: 11/25/2022]
Abstract
Sensory processing is affected in multiple neuropsychiatric disorders like schizophrenia and autism spectrum disorders. Genetic and environmental factors guide the formation and fine-tuning of brain circuitry necessary to receive, organize, and respond to sensory input in order to behave in a meaningful and consistent manner. During certain developmental stages the brain is sensitive to intrinsic and external factors. For example, disturbed expression levels of certain risk genes during critical neurodevelopmental periods may lead to exaggerated brain plasticity processes within the sensory circuits, and sensory stimulation immediately after birth contributes to fine-tuning of these circuits. Here, the neurodevelopmental trajectory of sensory circuit development will be described and related to some example risk gene mutations that are found in neuropsychiatric disorders. Subsequently, the flow of sensory information through these circuits and the relationship to synaptic plasticity will be described. Research focusing on the combined analyses of neural circuit development and functioning are necessary to expand our understanding of sensory processing and behavioral deficits that are relevant across the neuropsychiatric spectrum.
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Affiliation(s)
- Betty E Hornix
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - Robbert Havekes
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - Martien J H Kas
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands.
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43
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Ito S, Feldheim DA. The Mouse Superior Colliculus: An Emerging Model for Studying Circuit Formation and Function. Front Neural Circuits 2018; 12:10. [PMID: 29487505 PMCID: PMC5816945 DOI: 10.3389/fncir.2018.00010] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 01/22/2018] [Indexed: 11/30/2022] Open
Abstract
The superior colliculus (SC) is a midbrain area where visual, auditory and somatosensory information are integrated to initiate motor commands. The SC plays a central role in visual information processing in the mouse; it receives projections from 85% to 90% of the retinal ganglion cells (RGCs). While the mouse SC has been a long-standing model used to study retinotopic map formation, a number of technological advances in mouse molecular genetic techniques, large-scale physiological recordings and SC-dependent visual behavioral assays have made the mouse an even more ideal model to understand the relationship between circuitry and behavior.
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Affiliation(s)
- Shinya Ito
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - David A Feldheim
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
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44
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Barsh GR, Isabella AJ, Moens CB. Vagus Motor Neuron Topographic Map Determined by Parallel Mechanisms of hox5 Expression and Time of Axon Initiation. Curr Biol 2017; 27:3812-3825.e3. [PMID: 29225029 PMCID: PMC5755714 DOI: 10.1016/j.cub.2017.11.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 10/13/2017] [Accepted: 11/08/2017] [Indexed: 12/22/2022]
Abstract
Many networks throughout the nervous system are organized into topographic maps, where the positions of neuron cell bodies in the projecting field correspond with the positions of their axons in the target field. Previous studies of topographic map development show evidence for spatial patterning mechanisms, in which molecular determinants expressed across the projecting and target fields are matched directly in a point-to-point mapping process. Here, we describe a novel temporal mechanism of topographic map formation that depends on spatially regulated differences in the timing of axon outgrowth and functions in parallel with spatial point-to-point mapping mechanisms. We focus on the vagus motor neurons, which are topographically arranged in both mammals and fish. We show that cell position along the anterior-posterior axis of hindbrain rhombomere 8 determines expression of hox5 genes, which are expressed in posterior, but not anterior, vagus motor neurons. Using live imaging and transplantation in zebrafish embryos, we additionally reveal that axon initiation is delayed in posterior vagus motor neurons independent of neuron birth time. We show that hox5 expression directs topographic mapping without affecting time of axon outgrowth and that time of axon outgrowth directs topographic mapping without affecting hox5 expression. The vagus motor neuron topographic map is therefore determined by two mechanisms that act in parallel: a hox5-dependent spatial mechanism akin to classic mechanisms of topographic map formation and a novel axon outgrowth-dependent temporal mechanism in which time of axon formation is spatially regulated to direct axon targeting.
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Affiliation(s)
- Gabrielle R Barsh
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology, University of Washington, Seattle, WA 98195, USA; Medical Scientist Training Program, University of Washington, Seattle, WA 98195, USA
| | - Adam J Isabella
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Cecilia B Moens
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology, University of Washington, Seattle, WA 98195, USA.
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45
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Bollaerts I, Veys L, Geeraerts E, Andries L, De Groef L, Buyens T, Salinas-Navarro M, Moons L, Van Hove I. Complementary research models and methods to study axonal regeneration in the vertebrate retinofugal system. Brain Struct Funct 2017; 223:545-567. [DOI: 10.1007/s00429-017-1571-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/15/2017] [Indexed: 01/18/2023]
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46
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Guidance of retinal axons in mammals. Semin Cell Dev Biol 2017; 85:48-59. [PMID: 29174916 DOI: 10.1016/j.semcdb.2017.11.027] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Revised: 11/17/2017] [Accepted: 11/20/2017] [Indexed: 11/21/2022]
Abstract
In order to navigate through the surrounding environment many mammals, including humans, primarily rely on vision. The eye, composed of the choroid, sclera, retinal pigmented epithelium, cornea, lens, iris and retina, is the structure that receives the light and converts it into electrical impulses. The retina contains six major types of neurons involving in receiving and modifying visual information and passing it onto higher visual processing centres in the brain. Visual information is relayed to the brain via the axons of retinal ganglion cells (RGCs), a projection known as the optic pathway. The proper formation of this pathway during development is essential for normal vision in the adult individual. Along this pathway there are several points where visual axons face 'choices' in their direction of growth. Understanding how these choices are made has advanced significantly our knowledge of axon guidance mechanisms. Thus, the development of the visual pathway has served as an extremely useful model to reveal general principles of axon pathfinding throughout the nervous system. However, due to its particularities, some cellular and molecular mechanisms are specific for the visual circuit. Here we review both general and specific mechanisms involved in the guidance of mammalian RGC axons when they are traveling from the retina to the brain to establish precise and stereotyped connections that will sustain vision.
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47
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Guo H, Huang ZL, Wang W, Zhang SX, Li J, Cheng K, Xu K, He Y, Gui SW, Li PF, Wang HY, Dong ZF, Xie P. iTRAQ-Based Proteomics Suggests Ephb6 as a Potential Regulator of the ERK Pathway in the Prefrontal Cortex of Chronic Social Defeat Stress Model Mice. Proteomics Clin Appl 2017; 11. [PMID: 28967185 DOI: 10.1002/prca.201700115] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 09/03/2017] [Indexed: 01/07/2023]
Abstract
PURPOSE Major depressive disorder (MDD) is a worldwide concern and devastating psychiatric disease. The World Health Organization claims that MDD leads to at least 11.9% of the global burden of disease. However, the underlying pathophysiology mechanisms of MDD remain largely unknown. EXPERIMENTAL DESIGN Herein, we proteomic-based strategy is used to compare the prefrontal cortex (PFC) in chronic social defeat stress (CSDS) model mice with a control group. Based on pooled samples, differential proteins are identified in the PFC proteome using iTRAQ coupled with LC-MS/MS. RESULTS Ingenuity Pathway Analysis (IPA) is then followed to predict relevant pathways, with the ephrin receptor signaling pathway selected for further research. Additionally, as the selected key proteins of the ephrin receptor signaling pathway, ephrin type-B receptor 6 (EphB6) and the ERK pathway are validated by Western blotting. CONCLUSION AND CLINICAL RELEVANT Altogether, increased understanding of the ephrin receptor signaling pathway in MDD is provided, which implicates further investigation of PFC dysfunction induced by CSDS treatment.
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Affiliation(s)
- Hua Guo
- Department of Neurology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China.,Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Zhi-Lin Huang
- Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Wei Wang
- Department of Neurology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China.,Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Shu-Xiao Zhang
- Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Juan Li
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.,Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Ke Cheng
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.,Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Ke Xu
- Department of Neurology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China.,Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Yong He
- Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Si-Wen Gui
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.,Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Peng-Fei Li
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.,Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Hai-Yang Wang
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.,Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
| | - Zhi-Fang Dong
- Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Peng Xie
- Department of Neurology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China.,Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.,Institute of Neuroscience and Collaborative Innovation Center for Brain Science, Chongqing Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Chongqing, China
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Ventrella R, Kaplan N, Getsios S. Asymmetry at cell-cell interfaces direct cell sorting, boundary formation, and tissue morphogenesis. Exp Cell Res 2017; 358:58-64. [PMID: 28322822 PMCID: PMC5544567 DOI: 10.1016/j.yexcr.2017.03.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 03/13/2017] [Indexed: 01/22/2023]
Abstract
During development, cells of seemingly homogenous character sort themselves out into distinct compartments in order to generate cell types with specialized features that support tissue morphogenesis and function. This process is often driven by receptors at the cell membrane that probe the extracellular microenvironment for specific ligands and alter downstream signaling pathways impacting transcription, cytoskeletal organization, and cell adhesion to regulate cell sorting and subsequent boundary formation. This review will focus on two of these receptor families, Eph and Notch, both of which are intrinsically non-adhesive and are activated by a unique set of ligands that are asymmetrically distributed from their receptor on neighboring cells. Understanding the requirement of asymmetric ligand-receptor signaling at the membrane under homeostatic conditions gives insight into how misregulation of these pathways contributes to boundary disruption in diseases like cancer.
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Affiliation(s)
- Rosa Ventrella
- Department of Dermatology, Northwestern University, 303 E. Chicago Ave, Chicago, IL 60611, USA
| | - Nihal Kaplan
- Department of Dermatology, Northwestern University, 303 E. Chicago Ave, Chicago, IL 60611, USA
| | - Spiro Getsios
- Department of Dermatology, Northwestern University, 303 E. Chicago Ave, Chicago, IL 60611, USA.
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Revisiting chemoaffinity theory: Chemotactic implementation of topographic axonal projection. PLoS Comput Biol 2017; 13:e1005702. [PMID: 28792499 PMCID: PMC5562328 DOI: 10.1371/journal.pcbi.1005702] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/18/2017] [Accepted: 07/25/2017] [Indexed: 01/18/2023] Open
Abstract
Neural circuits are wired by chemotactic migration of growth cones guided by extracellular guidance cue gradients. How growth cone chemotaxis builds the macroscopic structure of the neural circuit is a fundamental question in neuroscience. I addressed this issue in the case of the ordered axonal projections called topographic maps in the retinotectal system. In the retina and tectum, the erythropoietin-producing hepatocellular (Eph) receptors and their ligands, the ephrins, are expressed in gradients. According to Sperry's chemoaffinity theory, gradients in both the source and target areas enable projecting axons to recognize their proper terminals, but how axons chemotactically decode their destinations is largely unknown. To identify the chemotactic mechanism of topographic mapping, I developed a mathematical model of intracellular signaling in the growth cone that focuses on the growth cone's unique chemotactic property of being attracted or repelled by the same guidance cues in different biological situations. The model presented mechanism by which the retinal growth cone reaches the correct terminal zone in the tectum through alternating chemotactic response between attraction and repulsion around a preferred concentration. The model also provided a unified understanding of the contrasting relationships between receptor expression levels and preferred ligand concentrations in EphA/ephrinA- and EphB/ephrinB-encoded topographic mappings. Thus, this study redefines the chemoaffinity theory in chemotactic terms.
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50
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Winklbauer R, Parent SE. Forces driving cell sorting in the amphibian embryo. Mech Dev 2017; 144:81-91. [DOI: 10.1016/j.mod.2016.09.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/18/2016] [Accepted: 09/29/2016] [Indexed: 01/05/2023]
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