1
|
Lymer S, Patel K, Lennon J, Blau J. Circadian clock neurons use activity-regulated gene expression for structural plasticity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.25.595887. [PMID: 38826237 PMCID: PMC11142243 DOI: 10.1101/2024.05.25.595887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Drosophila s-LNv circadian pacemaker neurons show dramatic structural plasticity, with their projections expanded at dawn and then retracted by dusk. This predictable plasticity makes s-LNvs ideal to study molecular mechanisms of plasticity. Although s-LNv plasticity is controlled by their molecular clock, changing s-LNv excitability also regulates plasticity. Here, we tested the idea that s-LNvs use activity-regulated genes to control plasticity. We found that inducing expression of either of the activity-regulated transcription factors Hr38 or Sr (orthologs of mammalian Nr4a1 and Egr1) is sufficient to rapidly expand s-LNv projections. Conversely, transiently knocking down expression of either Hr38 or sr blocks expansion of s-LNv projections at dawn. We show that Hr38 rapidly induces transcription of sif, which encodes a Rac1 GEF required for s-LNv plasticity rhythms. We conclude that the s-LNv molecular clock controls s-LNv excitability, which couples to an activity-regulated gene expression program to control s-LNv plasticity.
Collapse
|
2
|
Malin JA, Chen YC, Simon F, Keefer E, Desplan C. Spatial patterning controls neuron numbers in the Drosophila visual system. Dev Cell 2024; 59:1132-1145.e6. [PMID: 38531357 PMCID: PMC11078608 DOI: 10.1016/j.devcel.2024.03.004] [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: 08/10/2023] [Revised: 12/18/2023] [Accepted: 03/01/2024] [Indexed: 03/28/2024]
Abstract
Neurons must be made in the correct proportions to communicate with the appropriate synaptic partners and form functional circuits. In the Drosophila visual system, multiple subtypes of distal medulla (Dm) inhibitory interneurons are made in distinct, reproducible numbers-from 5 to 800 per optic lobe. These neurons are born from a crescent-shaped neuroepithelium called the outer proliferation center (OPC), which can be subdivided into specific domains based on transcription factor and growth factor expression. We fate mapped Dm neurons and found that more abundant neural types are born from larger neuroepithelial subdomains, while less abundant subtypes are born from smaller ones. Additionally, morphogenetic Dpp/BMP signaling provides a second layer of patterning that subdivides the neuroepithelium into smaller domains to provide more granular control of cell proportions. Apoptosis appears to play a minor role in regulating Dm neuron abundance. This work describes an underappreciated mechanism for the regulation of neuronal stoichiometry.
Collapse
Affiliation(s)
- Jennifer A Malin
- Department of Biology, New York University, New York, NY 10003, USA.
| | - Yen-Chung Chen
- Department of Biology, New York University, New York, NY 10003, USA
| | - Félix Simon
- Department of Biology, New York University, New York, NY 10003, USA
| | - Evelyn Keefer
- Department of Biology, New York University, New York, NY 10003, USA
| | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA.
| |
Collapse
|
3
|
Zhang Y, Li X. Development of the Drosophila Optic Lobe. Cold Spring Harb Protoc 2024; 2024:108156. [PMID: 37758285 DOI: 10.1101/pdb.top108156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
The Drosophila visual system has been a great model to study fundamental questions in neurobiology, such as neural fate specification, axon guidance, circuit formation, and information processing. The Drosophila visual system is composed of the compound eye and the optic lobe. The optic lobe is divided into four neuropils-namely, the lamina, medulla, lobula, and lobula plate. There are around 200 types of optic lobe neurons, which wire together to form a complex neural structure to processes visual information. These neurons are derived from two neuroepithelial structures-namely, the outer proliferation center (OPC) and the inner proliferation center (IPC), in the larval brain. Recent work on the Drosophila optic lobe has revealed basic principles underlying the development of this complex neural structure, and immunostaining has been a key tool in these studies. Here, we provide a brief overview of the Drosophila optic lobe structure and development, as revealed by immunostaining. First, we introduce the structure of the adult optic lobe. Then, we summarize recent advances in the study of neural fate specification during development of different parts of the optic lobe. Last, we briefly summarize general aspects of axon guidance and neuropil assembly in the optic lobe. With this review, we aim to familiarize readers with this complex neural structure and highlight the power of this great model to study neural development to facilitate further developmental and functional studies using this system.
Collapse
Affiliation(s)
- Yu Zhang
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Xin Li
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| |
Collapse
|
4
|
Simon F, Holguera I, Chen YC, Malin J, Valentino P, Erclik T, Desplan C. High-throughput identification of the spatial origins of Drosophila optic lobe neurons using single-cell mRNA-sequencing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.05.578975. [PMID: 38370610 PMCID: PMC10871188 DOI: 10.1101/2024.02.05.578975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
The medulla is the largest neuropil of the Drosophila optic lobe. It contains about 100 neuronal types that have been comprehensively characterized morphologically and molecularly. These neuronal types are specified from a larval neuroepithelium called the Outer Proliferation Center (OPC) via the integration of temporal, spatial, and Notch-driven mechanisms. Although we recently characterized the temporal windows of origin of all medulla neurons, as well as their Notch status, their spatial origins remained unknown. Here, we isolated cells from different OPC spatial domains and performed single-cell mRNA-sequencing to identify the neuronal types produced in these domains. This allowed us to characterize in a high-throughput manner the spatial origins of all medulla neurons and to identify two new spatial subdivisions of the OPC. Moreover, our work shows that the most abundant neuronal types are produced from epithelial domains of different sizes despite being present in a similar number of copies. Combined with our previously published scRNA-seq developmental atlas of the optic lobe, our work opens the door for further studies on how specification factor expression in progenitors impacts gene expression in developing and adult neurons.
Collapse
Affiliation(s)
- Félix Simon
- Department of Biology, New York University, New York, NY 10003, USA
| | - Isabel Holguera
- Department of Biology, New York University, New York, NY 10003, USA
| | - Yen-Chung Chen
- Department of Biology, New York University, New York, NY 10003, USA
| | - Jennifer Malin
- Department of Biology, New York University, New York, NY 10003, USA
| | - Priscilla Valentino
- Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Ted Erclik
- Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA
| |
Collapse
|
5
|
Xu C, Ramos TB, Marshall OJ, Doe CQ. Notch signaling and Bsh homeodomain activity are integrated to diversify Drosophila lamina neuron types. eLife 2024; 12:RP90136. [PMID: 38193901 PMCID: PMC10945509 DOI: 10.7554/elife.90136] [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] [Indexed: 01/10/2024] Open
Abstract
Notch signaling is an evolutionarily conserved pathway for specifying binary neuronal fates, yet how it specifies different fates in different contexts remains elusive. In our accompanying paper, using the Drosophila lamina neuron types (L1-L5) as a model, we show that the primary homeodomain transcription factor (HDTF) Bsh activates secondary HDTFs Ap (L4) and Pdm3 (L5) and specifies L4/L5 neuronal fates. Here we test the hypothesis that Notch signaling enables Bsh to differentially specify L4 and L5 fates. We show asymmetric Notch signaling between newborn L4 and L5 neurons, but they are not siblings; rather, Notch signaling in L4 is due to Delta expression in adjacent L1 neurons. While Notch signaling and Bsh expression are mutually independent, Notch is necessary and sufficient for Bsh to specify L4 fate over L5. The NotchON L4, compared to NotchOFF L5, has a distinct open chromatin landscape which allows Bsh to bind distinct genomic loci, leading to L4-specific identity gene transcription. We propose a novel model in which Notch signaling is integrated with the primary HDTF activity to diversify neuron types by directly or indirectly generating a distinct open chromatin landscape that constrains the pool of genes that a primary HDTF can activate.
Collapse
Affiliation(s)
- Chundi Xu
- Institute of Neuroscience, Howard Hughes Medical Institute, University of OregonEugeneUnited States
| | - Tyler B Ramos
- Institute of Neuroscience, Howard Hughes Medical Institute, University of OregonEugeneUnited States
| | - Owen J Marshall
- Menzies Institute for Medical Research, University of TasmaniaHobartAustralia
| | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of OregonEugeneUnited States
| |
Collapse
|
6
|
Qiao M. Factorized discriminant analysis for genetic signatures of neuronal phenotypes. Front Neuroinform 2023; 17:1265079. [PMID: 38156117 PMCID: PMC10752939 DOI: 10.3389/fninf.2023.1265079] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 11/06/2023] [Indexed: 12/30/2023] Open
Abstract
Navigating the complex landscape of single-cell transcriptomic data presents significant challenges. Central to this challenge is the identification of a meaningful representation of high-dimensional gene expression patterns that sheds light on the structural and functional properties of cell types. Pursuing model interpretability and computational simplicity, we often look for a linear transformation of the original data that aligns with key phenotypic features of cells. In response to this need, we introduce factorized linear discriminant analysis (FLDA), a novel method for linear dimensionality reduction. The crux of FLDA lies in identifying a linear function of gene expression levels that is highly correlated with one phenotypic feature while minimizing the influence of others. To augment this method, we integrate it with a sparsity-based regularization algorithm. This integration is crucial as it selects a subset of genes pivotal to a specific phenotypic feature or a combination thereof. To illustrate the effectiveness of FLDA, we apply it to transcriptomic datasets from neurons in the Drosophila optic lobe. We demonstrate that FLDA not only captures the inherent structural patterns aligned with phenotypic features but also uncovers key genes associated with each phenotype.
Collapse
|
7
|
Carrier Y, Rio LQ, Formicola N, de Sousa-Xavier V, Tabet M, Chen YCD, Wislez M, Orts L, Pinto-Teixeira F. Biased cell adhesion organizes a circuit for visual motion integration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.11.571076. [PMID: 38168373 PMCID: PMC10760042 DOI: 10.1101/2023.12.11.571076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Layer specific computations in the brain rely on neuronal processes establishing synaptic connections with specific partners in distinct laminae. In the Drosophila lobula plate neuropile, the axons of the four subtypes of T4 and T5 visual motion direction-selective neurons segregate into four layers, based on their directional preference, and form synapses with distinct subsets of postsynaptic neurons. Four bi-stratified inhibitory lobula plate intrinsic cells exhibit a consistent synaptic pattern, receiving excitatory T4/T5 inputs in one layer, and conveying inhibitory signals to an adjacent layer. This layered arrangement establishes motion opponency. Here, we identify layer-specific expression of different receptor-ligand pairs belonging to the Beat and Side families of Cell Adhesion Molecules (CAMs) between T4/T5 neurons and their postsynaptic partners. Genetic analysis reveals that Beat/Side mediated interactions are required to restrict T4/T5 axonal innervation to a single layer. We propose that Beat/Side contribute to synaptic specificity by biasing adhesion between synaptic partners before synaptogenesis.
Collapse
Affiliation(s)
- Yannick Carrier
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Laura Quintana Rio
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Nadia Formicola
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Vicente de Sousa-Xavier
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Maha Tabet
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | | | - Maëva Wislez
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Lisa Orts
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Filipe Pinto-Teixeira
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| |
Collapse
|
8
|
Mannino MC, Cassidy MB, Florez S, Rusan Z, Chakraborty S, Schoborg T. Mutations in abnormal spindle disrupt temporal transcription factor expression and trigger immune responses in the Drosophila brain. Genetics 2023; 225:iyad188. [PMID: 37831641 PMCID: PMC10697820 DOI: 10.1093/genetics/iyad188] [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: 08/30/2023] [Revised: 08/30/2023] [Accepted: 09/25/2023] [Indexed: 10/15/2023] Open
Abstract
The coordination of cellular behaviors during neurodevelopment is critical for determining the form, function, and size of the central nervous system (CNS). Mutations in the vertebrate Abnormal Spindle-Like, Microcephaly Associated (ASPM) gene and its Drosophila melanogaster ortholog abnormal spindle (asp) lead to microcephaly (MCPH), a reduction in overall brain size whose etiology remains poorly defined. Here, we provide the neurodevelopmental transcriptional landscape for a Drosophila model for autosomal recessive primary microcephaly-5 (MCPH5) and extend our findings into the functional realm to identify the key cellular mechanisms responsible for Asp-dependent brain growth and development. We identify multiple transcriptomic signatures, including new patterns of coexpressed genes in the developing CNS. Defects in optic lobe neurogenesis were detected in larval brains through downregulation of temporal transcription factors (tTFs) and Notch signaling targets, which correlated with a significant reduction in brain size and total cell numbers during the neurogenic window of development. We also found inflammation as a hallmark of asp mutant brains, detectable throughout every stage of CNS development, which also contributes to the brain size phenotype. Finally, we show that apoptosis is not a primary driver of the asp mutant brain phenotypes, further highlighting an intrinsic Asp-dependent neurogenesis promotion mechanism that is independent of cell death. Collectively, our results suggest that the etiology of the asp mutant brain phenotype is complex and that a comprehensive view of the cellular basis of the disorder requires an understanding of how multiple pathway inputs collectively determine tissue size and architecture.
Collapse
Affiliation(s)
- Maria C Mannino
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | | | - Steven Florez
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Zeid Rusan
- Personalis, Inc., Fremont, CA 94555, USA
| | - Shalini Chakraborty
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Todd Schoborg
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| |
Collapse
|
9
|
Abstract
How neurons detect the direction of motion is a prime example of neural computation: Motion vision is found in the visual systems of virtually all sighted animals, it is important for survival, and it requires interesting computations with well-defined linear and nonlinear processing steps-yet the whole process is of moderate complexity. The genetic methods available in the fruit fly Drosophila and the charting of a connectome of its visual system have led to rapid progress and unprecedented detail in our understanding of how neurons compute the direction of motion in this organism. The picture that emerged incorporates not only the identity, morphology, and synaptic connectivity of each neuron involved but also its neurotransmitters, its receptors, and their subcellular localization. Together with the neurons' membrane potential responses to visual stimulation, this information provides the basis for a biophysically realistic model of the circuit that computes the direction of visual motion.
Collapse
Affiliation(s)
- Alexander Borst
- Max Planck Institute for Biological Intelligence, Martinsried, Germany; ,
| | - Lukas N Groschner
- Max Planck Institute for Biological Intelligence, Martinsried, Germany; ,
| |
Collapse
|
10
|
Mannino MC, Bartels Cassidy M, Florez S, Rusan Z, Chakraborty S, Schoborg T. The neurodevelopmental transcriptome of the Drosophila melanogaster microcephaly gene abnormal spindle reveals a role for temporal transcription factors and the immune system in regulating brain size. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.09.523369. [PMID: 36711768 PMCID: PMC9882087 DOI: 10.1101/2023.01.09.523369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The coordination of cellular behaviors during neurodevelopment is critical for determining the form, function, and size of the central nervous system. Mutations in the vertebrate Abnormal Spindle-Like, Microcephaly Associated (ASPM) gene and its Drosophila melanogaster ortholog abnormal spindle (asp) lead to microcephaly, a reduction in overall brain size whose etiology remains poorly defined. Here we provide the neurodevelopmental transcriptional landscape for a Drosophila model for autosomal recessive primary microcephaly (MCPH) and extend our findings into the functional realm in an attempt to identify the key cellular mechanisms responsible for Asp-dependent brain growth and development. We identify multiple transcriptomic signatures, including new patterns of co-expressed genes in the developing CNS. Defects in optic lobe neurogenesis were detected in larval brains through downregulation of temporal transcription factors (tTFs) and Notch signaling targets, which correlated with a significant reduction in brain size and total cell numbers during the neurogenic window of development. We also found inflammation as a hallmark of asp MCPH brains, detectable throughout every stage of CNS development, which also contributes to the brain size phenotype. Finally, we show that apoptosis is not a primary driver of the asp MCPH phenotype, further highlighting an intrinsic Asp-dependent neurogenesis promotion mechanism that is independent of cell death. Collectively, our results suggest that the etiology of asp MCPH is complex and that a comprehensive view of the cellular basis of the disorder requires an understanding of how multiple pathway inputs collectively determine the microcephaly phenotype.
Collapse
Affiliation(s)
- Maria C. Mannino
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | | | - Steven Florez
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | | | - Shalini Chakraborty
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Todd Schoborg
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| |
Collapse
|
11
|
Dombrovski M, Peek MY, Park JY, Vaccari A, Sumathipala M, Morrow C, Breads P, Zhao A, Kurmangaliyev YZ, Sanfilippo P, Rehan A, Polsky J, Alghailani S, Tenshaw E, Namiki S, Zipursky SL, Card GM. Synaptic gradients transform object location to action. Nature 2023; 613:534-542. [PMID: 36599984 PMCID: PMC9849133 DOI: 10.1038/s41586-022-05562-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 11/11/2022] [Indexed: 01/06/2023]
Abstract
To survive, animals must convert sensory information into appropriate behaviours1,2. Vision is a common sense for locating ethologically relevant stimuli and guiding motor responses3-5. How circuitry converts object location in retinal coordinates to movement direction in body coordinates remains largely unknown. Here we show through behaviour, physiology, anatomy and connectomics in Drosophila that visuomotor transformation occurs by conversion of topographic maps formed by the dendrites of feature-detecting visual projection neurons (VPNs)6,7 into synaptic weight gradients of VPN outputs onto central brain neurons. We demonstrate how this gradient motif transforms the anteroposterior location of a visual looming stimulus into the fly's directional escape. Specifically, we discover that two neurons postsynaptic to a looming-responsive VPN type promote opposite takeoff directions. Opposite synaptic weight gradients onto these neurons from looming VPNs in different visual field regions convert localized looming threats into correctly oriented escapes. For a second looming-responsive VPN type, we demonstrate graded responses along the dorsoventral axis. We show that this synaptic gradient motif generalizes across all 20 primary VPN cell types and most often arises without VPN axon topography. Synaptic gradients may thus be a general mechanism for conveying spatial features of sensory information into directed motor outputs.
Collapse
Affiliation(s)
- Mark Dombrovski
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Martin Y Peek
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Jin-Yong Park
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Andrea Vaccari
- Department of Computer Science, Middlebury College, Middlebury, VT, USA
| | | | - Carmen Morrow
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Patrick Breads
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Arthur Zhao
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Yerbol Z Kurmangaliyev
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Piero Sanfilippo
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Aadil Rehan
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Jason Polsky
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Shada Alghailani
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Emily Tenshaw
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Shigehiro Namiki
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.,Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, Japan
| | - S Lawrence Zipursky
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
| | - Gwyneth M Card
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA. .,Department of Neuroscience, Howard Hughes Medical Institute, The Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA.
| |
Collapse
|
12
|
Barnatan Y, Tomsic D, Cámera A, Sztarker J. Matched function of the neuropil processing optic flow in flies and crabs: the lobula plate mediates optomotor responses in Neohelice granulata. Proc Biol Sci 2022; 289:20220812. [PMID: 35975436 PMCID: PMC9382210 DOI: 10.1098/rspb.2022.0812] [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: 04/29/2022] [Accepted: 07/12/2022] [Indexed: 11/12/2022] Open
Abstract
When an animal rotates (whether it is an arthropod, a fish, a bird or a human) a drift of the visual panorama occurs over its retina, termed optic flow. The image is stabilized by compensatory behaviours (driven by the movement of the eyes, head or the whole body depending on the animal) collectively termed optomotor responses. The dipteran lobula plate has been consistently linked with optic flow processing and the control of optomotor responses. Crabs have a neuropil similarly located and interconnected in the optic lobes, therefore referred to as a lobula plate too. Here we show that the crabs' lobula plate is required for normal optomotor responses since the response was lost or severely impaired in animals whose lobula plate had been lesioned. The effect was behaviour-specific, since avoidance responses to approaching visual stimuli were not affected. Crabs require simpler optic flow processing than flies (because they move slower and in two-dimensional instead of three-dimensional space), consequently their lobula plates are relatively smaller. Nonetheless, they perform the same essential role in the visual control of behaviour. Our findings add a fundamental piece to the current debate on the evolutionary relationship between the lobula plates of insects and crustaceans.
Collapse
Affiliation(s)
- Yair Barnatan
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE) CONICET-Universidad de Buenos Aires, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | - Daniel Tomsic
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE) CONICET-Universidad de Buenos Aires, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, 1428 Buenos Aires, Argentina
- Departamento de Fisiología, Biología Molecular y Celular Dr. Héctor Maldonado, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | - Alejandro Cámera
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE) CONICET-Universidad de Buenos Aires, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | - Julieta Sztarker
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE) CONICET-Universidad de Buenos Aires, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, 1428 Buenos Aires, Argentina
- Departamento de Fisiología, Biología Molecular y Celular Dr. Héctor Maldonado, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| |
Collapse
|
13
|
Chen YC, Konstantinides N. Integration of Spatial and Temporal Patterning in the Invertebrate and Vertebrate Nervous System. Front Neurosci 2022; 16:854422. [PMID: 35392413 PMCID: PMC8981590 DOI: 10.3389/fnins.2022.854422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/15/2022] [Indexed: 11/25/2022] Open
Abstract
The nervous system is one of the most sophisticated animal tissues, consisting of thousands of interconnected cell types. How the nervous system develops its diversity from a few neural stem cells remains a challenging question. Spatial and temporal patterning mechanisms provide an efficient model through which diversity can be generated. The molecular mechanism of spatiotemporal patterning has been studied extensively in Drosophila melanogaster, where distinct sets of transcription factors define the spatial domains and temporal windows that give rise to different cell types. Similarly, in vertebrates, spatial domains defined by transcription factors produce different types of neurons in the brain and neural tube. At the same time, different cortical neuronal types are generated within the same cell lineage with a specific birth order. However, we still do not understand how the orthogonal information of spatial and temporal patterning is integrated into the progenitor and post-mitotic cells to combinatorially give rise to different neurons. In this review, after introducing spatial and temporal patterning in Drosophila and mice, we discuss possible mechanisms that neural progenitors may use to integrate spatial and temporal information. We finally review the functional implications of spatial and temporal patterning and conclude envisaging how small alterations of these mechanisms can lead to the evolution of new neuronal cell types.
Collapse
Affiliation(s)
- Yen-Chung Chen
- Department of Biology, New York University, New York, NY, United States
| | - Nikolaos Konstantinides
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| |
Collapse
|
14
|
Wang YW, Wreden CC, Levy M, Meng JL, Marshall ZD, MacLean J, Heckscher E. Sequential addition of neuronal stem cell temporal cohorts generates a feed-forward circuit in the Drosophila larval nerve cord. eLife 2022; 11:79276. [PMID: 35723253 PMCID: PMC9333992 DOI: 10.7554/elife.79276] [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: 04/06/2022] [Accepted: 06/17/2022] [Indexed: 02/06/2023] Open
Abstract
How circuits self-assemble starting from neuronal stem cells is a fundamental question in developmental neurobiology. Here, we addressed how neurons from different stem cell lineages wire with each other to form a specific circuit motif. In Drosophila larvae, we combined developmental genetics (twin-spot mosaic analysis with a repressible cell marker, multi-color flip out, permanent labeling) with circuit analysis (calcium imaging, connectomics, network science). For many lineages, neuronal progeny are organized into subunits called temporal cohorts. Temporal cohorts are subsets of neurons born within a tight time window that have shared circuit-level function. We find sharp transitions in patterns of input connectivity at temporal cohort boundaries. In addition, we identify a feed-forward circuit that encodes the onset of vibration stimuli. This feed-forward circuit is assembled by preferential connectivity between temporal cohorts from different lineages. Connectivity does not follow the often-cited early-to-early, late-to-late model. Instead, the circuit is formed by sequential addition of temporal cohorts from different lineages, with circuit output neurons born before circuit input neurons. Further, we generate new tools for the fly community. Our data raise the possibility that sequential addition of neurons (with outputs oldest and inputs youngest) could be one fundamental strategy for assembling feed-forward circuits.
Collapse
Affiliation(s)
- Yi-wen Wang
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
| | - Chris C Wreden
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
| | - Maayan Levy
- Committee on Computational Neuroscience, University of ChicagoChicagoUnited States
| | - Julia L Meng
- Program in Cell and Molecular Biology, University of ChicagoChicagoUnited States
| | - Zarion D Marshall
- Committee on Neurobiology, University of ChicagoChicagoUnited States
| | - Jason MacLean
- Committee on Computational Neuroscience, University of ChicagoChicagoUnited States,Committee on Neurobiology, University of ChicagoChicagoUnited States,Department of Neurobiology, University of ChicagoChicagoUnited States,University of Chicago Neuroscience InstituteChicagoUnited States
| | - Ellie Heckscher
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States,Committee on Computational Neuroscience, University of ChicagoChicagoUnited States,Program in Cell and Molecular Biology, University of ChicagoChicagoUnited States,Department of Neurobiology, University of ChicagoChicagoUnited States,University of Chicago Neuroscience InstituteChicagoUnited States
| |
Collapse
|
15
|
Simon F, Konstantinides N. Single-cell transcriptomics in the Drosophila visual system: Advances and perspectives on cell identity regulation, connectivity, and neuronal diversity evolution. Dev Biol 2021; 479:107-122. [PMID: 34375653 DOI: 10.1016/j.ydbio.2021.08.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 07/10/2021] [Accepted: 08/03/2021] [Indexed: 11/17/2022]
Abstract
The Drosophila visual system supports complex behaviors and shares many of its anatomical and molecular features with the vertebrate brain. Yet, it contains a much more manageable number of neurons and neuronal types. In addition to the extensive Drosophila genetic toolbox, this relative simplicity has allowed decades of work to yield a detailed account of its neuronal type diversity, morphology, connectivity and specification mechanisms. In the past three years, numerous studies have applied large scale single-cell transcriptomic approaches to the Drosophila visual system and have provided access to the complete gene expression profile of most neuronal types throughout development. This makes the fly visual system particularly well suited to perform detailed studies of the genetic mechanisms underlying the evolution and development of neuronal systems. Here, we highlight how these transcriptomic resources allow exploring long-standing biological questions under a new light. We first present the efforts made to characterize neuronal diversity in the Drosophila visual system and suggest ways to further improve this description. We then discuss current advances allowed by the single-cell datasets, and envisage how these datasets can be further leveraged to address fundamental questions regarding the regulation of neuronal identity, neuronal circuit development and the evolution of neuronal diversity.
Collapse
Affiliation(s)
- Félix Simon
- Department of Biology, New York University, New York, NY, 10003, USA.
| | - Nikolaos Konstantinides
- Department of Biology, New York University, New York, NY, 10003, USA; Institut Jacques Monod, Centre National de la Recherche Scientifique-UMR 7592, Université Paris Diderot, Paris, France.
| |
Collapse
|
16
|
Profile of Claude Desplan. Proc Natl Acad Sci U S A 2021; 118:2110547118. [PMID: 34244438 DOI: 10.1073/pnas.2110547118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
17
|
Neural specification, targeting, and circuit formation during visual system assembly. Proc Natl Acad Sci U S A 2021; 118:2101823118. [PMID: 34183440 DOI: 10.1073/pnas.2101823118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Like other sensory systems, the visual system is topographically organized: Its sensory neurons, the photoreceptors, and their targets maintain point-to-point correspondence in physical space, forming a retinotopic map. The iterative wiring of circuits in the visual system conveniently facilitates the study of its development. Over the past few decades, experiments in Drosophila have shed light on the principles that guide the specification and connectivity of visual system neurons. In this review, we describe the main findings unearthed by the study of the Drosophila visual system and compare them with similar events in mammals. We focus on how temporal and spatial patterning generates diverse cell types, how guidance molecules distribute the axons and dendrites of neurons within the correct target regions, how vertebrates and invertebrates generate their retinotopic map, and the molecules and mechanisms required for neuronal migration. We suggest that basic principles used to wire the fly visual system are broadly applicable to other systems and highlight its importance as a model to study nervous system development.
Collapse
|
18
|
Transcription factor encoding of neuron subtype: Strategies that specify arbor pattern. Curr Opin Neurobiol 2021; 69:149-158. [PMID: 33895620 DOI: 10.1016/j.conb.2021.03.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/21/2021] [Accepted: 03/23/2021] [Indexed: 01/01/2023]
Abstract
Dendrite and axon arbors form scaffolds that connect a neuron to its partners; they are patterned to support the specific connectivity and computational requirements of each neuron subtype. Transcription factor networks control the specification of neuron subtypes, and the consequent diversification of their stereotyped arbor patterns during differentiation. We outline how the differentiation trajectories of stereotyped arbors are shaped by hierarchical deployment of precursor cell and postmitotic transcription factors. These transcription factors exert modular control over the dendrite and axon features of a single neuron, create spatial and functional compartmentalization of an arbor, instruct implementation of developmental patterning rules, and exert operational control over the cell biological processes that construct an arbor.
Collapse
|
19
|
Guzmán-Palma P, Contreras EG, Mora N, Smith M, González-Ramírez MC, Campusano JM, Sierralta J, Hassan BA, Oliva C. Slit/Robo Signaling Regulates Multiple Stages of the Development of the Drosophila Motion Detection System. Front Cell Dev Biol 2021; 9:612645. [PMID: 33968921 PMCID: PMC8097104 DOI: 10.3389/fcell.2021.612645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 03/24/2021] [Indexed: 11/29/2022] Open
Abstract
Neurogenesis is achieved through a sequence of steps that include specification and differentiation of progenitors into mature neurons. Frequently, precursors migrate to distinct positions before terminal differentiation. The Slit-Robo pathway, formed by the secreted ligand Slit and its membrane bound receptor Robo, was first discovered as a regulator of axonal growth. However, today, it is accepted that this pathway can regulate different cellular processes even outside the nervous system. Since most of the studies performed in the nervous system have been focused on axonal and dendritic growth, it is less clear how versatile is this signaling pathway in the developing nervous system. Here we describe the participation of the Slit-Robo pathway in the development of motion sensitive neurons of the Drosophila visual system. We show that Slit and Robo receptors are expressed in different stages during the neurogenesis of motion sensitive neurons. Furthermore, we find that Slit and Robo regulate multiple aspects of their development including neuronal precursor migration, cell segregation between neural stem cells and daughter cells and formation of their connectivity pattern. Specifically, loss of function of slit or robo receptors in differentiated motion sensitive neurons impairs dendritic targeting, while knocking down robo receptors in migratory progenitors or neural stem cells leads to structural defects in the adult optic lobe neuropil, caused by migration and cell segregation defects during larval development. Thus, our work reveals the co-option of the Slit-Robo signaling pathway in distinct developmental stages of a neural lineage.
Collapse
Affiliation(s)
- Pablo Guzmán-Palma
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Esteban G Contreras
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Natalia Mora
- Institut du Cerveau-Paris Brain Institute (ICM), Inserm, CNRS, Hôpital Pitié-Salpêtrière, Sorbonne Université, Paris, France
| | - Macarena Smith
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - M Constanza González-Ramírez
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jorge M Campusano
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jimena Sierralta
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Bassem A Hassan
- Institut du Cerveau-Paris Brain Institute (ICM), Inserm, CNRS, Hôpital Pitié-Salpêtrière, Sorbonne Université, Paris, France
| | - Carlos Oliva
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| |
Collapse
|
20
|
Sancer G, Wernet MF. The development and function of neuronal subtypes processing color and skylight polarization in the optic lobes of Drosophila melanogaster. ARTHROPOD STRUCTURE & DEVELOPMENT 2021; 61:101012. [PMID: 33618155 DOI: 10.1016/j.asd.2020.101012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 11/01/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
The retinal mosaics of many insects contain different ommatidial subtypes harboring photoreceptors that are both molecularly and morphologically specialized for comparing between different wavelengths versus detecting the orientation of skylight polarization. The neural circuits underlying these different inputs and the characterization of their specific cellular elements are the subject of intense research. Here we review recent progress on the description of both assembly and function of color and skylight polarization circuitry, by focusing on two cell types located in the distal portion of the medulla neuropil of the fruit fly Drosophila melanogaster's optic lobes, called Dm8 and Dm9. In the main part of the retina, Dm8 cells fall into two molecularly distinct subtypes whose center becomes specifically connected to either one of randomly distributed 'pale' or 'yellow' R7 photoreceptor fates during development. Only in the 'dorsal rim area' (DRA), both polarization-sensitive R7 and R8 photoreceptors are connected to different Dm8-like cell types, called Dm-DRA1 and Dm-DRA2, respectively. An additional layer of interommatidial integration is introduced by Dm9 cells, which receive input from multiple neighboring R7 and R8 cells, as well as providing feedback synapses back into these photoreceptors. As a result, the response properties of color-sensitive photoreceptor terminals are sculpted towards being both maximally decorrelated, as well as harboring several levels of opponency (both columnar as well as intercolumnar). In the DRA, individual Dm9 cells appear to mix both polarization and color signals, thereby potentially serving as the first level of integration of different celestial stimuli. The molecular mechanisms underlying the establishment of these synaptic connections are beginning to be revealed, by using a combination of live imaging, developmental genetic studies, and cell type-specific transcriptomics.
Collapse
Affiliation(s)
- Gizem Sancer
- Freie Universität Berlin, Fachbereich Biologie, Chemie und Pharmazie, Institut für Biologie - Neurobiologie, Königin-Luise Strasse 1-3, 14195 Berlin, Germany
| | - Mathias F Wernet
- Freie Universität Berlin, Fachbereich Biologie, Chemie und Pharmazie, Institut für Biologie - Neurobiologie, Königin-Luise Strasse 1-3, 14195 Berlin, Germany.
| |
Collapse
|
21
|
Rossi AM, Jafari S, Desplan C. Integrated Patterning Programs During Drosophila Development Generate the Diversity of Neurons and Control Their Mature Properties. Annu Rev Neurosci 2021; 44:153-172. [PMID: 33556251 DOI: 10.1146/annurev-neuro-102120-014813] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
During the approximately 5 days of Drosophila neurogenesis (late embryogenesis to the beginning of pupation), a limited number of neural stem cells produce approximately 200,000 neurons comprising hundreds of cell types. To build a functional nervous system, neuronal types need to be produced in the proper places, appropriate numbers, and correct times. We discuss how neural stem cells (neuroblasts) obtain so-called area codes for their positions in the nervous system (spatial patterning) and how they keep time to sequentially produce neurons with unique fates (temporal patterning). We focus on specific examples that demonstrate how a relatively simple patterning system (Notch) can be used reiteratively to generate different neuronal types. We also speculate on how different modes of temporal patterning that operate over short versus long time periods might be linked. We end by discussing how specification programs are integrated and lead to the terminal features of different neuronal types.
Collapse
Affiliation(s)
- Anthony M Rossi
- Department of Biology, New York University, New York, NY 10003, USA; .,Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Shadi Jafari
- Department of Biology, New York University, New York, NY 10003, USA;
| | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA;
| |
Collapse
|
22
|
Wang H, Fu Q, Wang H, Baxter P, Peng J, Yue S. A bioinspired angular velocity decoding neural network model for visually guided flights. Neural Netw 2021; 136:180-193. [PMID: 33494035 DOI: 10.1016/j.neunet.2020.12.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 12/03/2020] [Accepted: 12/07/2020] [Indexed: 11/17/2022]
Abstract
Efficient and robust motion perception systems are important pre-requisites for achieving visually guided flights in future micro air vehicles. As a source of inspiration, the visual neural networks of flying insects such as honeybee and Drosophila provide ideal examples on which to base artificial motion perception models. In this paper, we have used this approach to develop a novel method that solves the fundamental problem of estimating angular velocity for visually guided flights. Compared with previous models, our elementary motion detector (EMD) based model uses a separate texture estimation pathway to effectively decode angular velocity, and demonstrates considerable independence from the spatial frequency and contrast of the gratings. Using the Unity development platform the model is further tested for tunnel centering and terrain following paradigms in order to reproduce the visually guided flight behaviors of honeybees. In a series of controlled trials, the virtual bee utilizes the proposed angular velocity control schemes to accurately navigate through a patterned tunnel, maintaining a suitable distance from the undulating textured terrain. The results are consistent with both neuron spike recordings and behavioral path recordings of real honeybees, thereby demonstrating the model's potential for implementation in micro air vehicles which have only visual sensors.
Collapse
Affiliation(s)
- Huatian Wang
- Computational Intelligence Laboratory (CIL), University of Lincoln, Lincoln, UK; Machine Life and Intelligence Research Center, Guangzhou University, Guangzhou, China
| | - Qinbing Fu
- Machine Life and Intelligence Research Center, Guangzhou University, Guangzhou, China; Computational Intelligence Laboratory (CIL), University of Lincoln, Lincoln, UK
| | - Hongxin Wang
- Machine Life and Intelligence Research Center, Guangzhou University, Guangzhou, China; Computational Intelligence Laboratory (CIL), University of Lincoln, Lincoln, UK
| | - Paul Baxter
- Computational Intelligence Laboratory (CIL), University of Lincoln, Lincoln, UK
| | - Jigen Peng
- School of Mathematics and Information Science, Guangzhou University, Guangzhou, China; Machine Life and Intelligence Research Center, Guangzhou University, Guangzhou, China.
| | - Shigang Yue
- Machine Life and Intelligence Research Center, Guangzhou University, Guangzhou, China; Computational Intelligence Laboratory (CIL), University of Lincoln, Lincoln, UK.
| |
Collapse
|
23
|
Neuronal diversity and convergence in a visual system developmental atlas. Nature 2020; 589:88-95. [PMID: 33149298 PMCID: PMC7790857 DOI: 10.1038/s41586-020-2879-3] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 08/27/2020] [Indexed: 01/01/2023]
Abstract
Deciphering how neuronal diversity is established and maintained requires a detailed knowledge of neuronal gene expression throughout development. In contrast to mammalian brains1,2, the large neuronal diversity of the Drosophila optic lobes3 and its connectome4–6 are almost completely characterized. However, a molecular characterization of this diversity, particularly during development, has been lacking. We present novel insights into brain development through a nearly exhaustive description of the transcriptomic diversity of the optic lobes. We acquired the transcriptome of 275,000 single-cells at adult and five pupal stages, and developed a machine learning framework to assign them to almost 200 cell-types at all timepoints. We discovered two large neuronal populations that wrap neuropils during development but die just before adulthood, as well as neuronal subtypes that partition dorsal and ventral visual circuits by differential Wnt signaling throughout development. Moreover, we showed that neurons of the same type but produced days apart synchronize their transcriptomes shortly after being produced. We also resolved during synaptogenesis neuronal subtypes that converge to indistinguishable transcriptomic profiles in adults while greatly differing in morphology and connectivity. Our datasets almost completely account for the known neuronal diversity of the optic lobes and serve as a paradigm to understand brain development across species.
Collapse
|
24
|
Mizoguchi T, Fukada M, Iihama M, Song X, Fukagawa S, Kuwabara S, Omaru S, Higashijima SI, Itoh M. Transient activation of the Notch-her15.1 axis plays an important role in the maturation of V2b interneurons. Development 2020; 147:147/16/dev191312. [PMID: 32855202 DOI: 10.1242/dev.191312] [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] [Received: 06/05/2020] [Accepted: 07/20/2020] [Indexed: 12/12/2022]
Abstract
In the vertebrate ventral spinal cord, p2 progenitors give rise to two interneuron subtypes: excitatory V2a interneurons and inhibitory V2b interneurons. In the differentiation of V2a and V2b cells, Notch signaling promotes V2b fate at the expense of V2a fate. Later, V2b cells extend axons along the ipsilateral side of the spinal cord and express the inhibitory transmitter GABA. Notch signaling has been reported to inhibit the axonal outgrowth of mature neurons of the central nervous system; however, it remains unknown how Notch signaling modulates V2b neurite outgrowth and maturation into GABAergic neurons. Here, we have investigated neuron-specific Notch functions regarding V2b axon growth and maturation into zebrafish GABAergic neurons. We found that continuous neuron-specific Notch activation enhanced V2b fate determination but inhibited V2b axonal outgrowth and maturation into GABAergic neurons. These results suggest that Notch signaling activation is required for V2b fate determination, whereas its downregulation at a later stage is essential for V2b maturation. Accordingly, we found that a Notch signaling downstream gene, her15.1, showed biased expression in V2 linage cells and downregulated expression during the maturation of V2b cells, and continuous expression of her15.1 repressed V2b axogenesis. Our data suggest that spatiotemporal control of Notch signaling activity is required for V2b fate determination, maturation and axogenesis.
Collapse
Affiliation(s)
- Takamasa Mizoguchi
- Graduate School of Pharmaceutical Science, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Michi Fukada
- Graduate School of Pharmaceutical Science, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Miku Iihama
- Graduate School of Pharmaceutical Science, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Xuehui Song
- Graduate School of Pharmaceutical Science, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Shun Fukagawa
- Graduate School of Pharmaceutical Science, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Shuhei Kuwabara
- Graduate School of Pharmaceutical Science, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Shuhei Omaru
- Graduate School of Pharmaceutical Science, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Shin-Ichi Higashijima
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan.,Graduate University for Advanced Studies, Okazaki, Aichi 444-8787, Japan
| | - Motoyuki Itoh
- Graduate School of Pharmaceutical Science, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| |
Collapse
|
25
|
Isaacman-Beck J, Paik KC, Wienecke CFR, Yang HH, Fisher YE, Wang IE, Ishida IG, Maimon G, Wilson RI, Clandinin TR. SPARC enables genetic manipulation of precise proportions of cells. Nat Neurosci 2020; 23:1168-1175. [PMID: 32690967 PMCID: PMC7939234 DOI: 10.1038/s41593-020-0668-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 06/12/2020] [Indexed: 11/17/2022]
Abstract
Many experimental approaches rely on controlling gene expression in select subsets of cells within an individual animal. However, reproducibly targeting transgene expression to specific fractions of a genetically defined cell type is challenging. We developed Sparse Predictive Activity through Recombinase Competition (SPARC), a generalizable toolkit that can express any effector in precise proportions of post-mitotic cells in Drosophila. Using this approach, we demonstrate targeted expression of many effectors in several cell types and apply these tools to calcium imaging of individual neurons and optogenetic manipulation of sparse cell populations in vivo.
Collapse
Affiliation(s)
| | - Kristine C Paik
- Department of Neurobiology, Stanford University, Stanford, CA, USA.,Department of Medicine, Weill Cornell Medical College, New York, NY, USA
| | | | - Helen H Yang
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Yvette E Fisher
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Irving E Wang
- Department of Neurobiology, Stanford University, Stanford, CA, USA.,Freenome, South San Francisco, CA, USA
| | - Itzel G Ishida
- Laboratory of Integrative Brain Function and Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA
| | - Gaby Maimon
- Laboratory of Integrative Brain Function and Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA
| | - Rachel I Wilson
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | | |
Collapse
|
26
|
Salazar JL, Yang SA, Yamamoto S. Post-Developmental Roles of Notch Signaling in the Nervous System. Biomolecules 2020; 10:biom10070985. [PMID: 32630239 PMCID: PMC7408554 DOI: 10.3390/biom10070985] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 12/14/2022] Open
Abstract
Since its discovery in Drosophila, the Notch signaling pathway has been studied in numerous developmental contexts in diverse multicellular organisms. The role of Notch signaling in nervous system development has been extensively investigated by numerous scientists, partially because many of the core Notch signaling components were initially identified through their dramatic ‘neurogenic’ phenotype of developing fruit fly embryos. Components of the Notch signaling pathway continue to be expressed in mature neurons and glia cells, which is suggestive of a role in the post-developmental nervous system. The Notch pathway has been, so far, implicated in learning and memory, social behavior, addiction, and other complex behaviors using genetic model organisms including Drosophila and mice. Additionally, Notch signaling has been shown to play a modulatory role in several neurodegenerative disease model animals and in mediating neural toxicity of several environmental factors. In this paper, we summarize the knowledge pertaining to the post-developmental roles of Notch signaling in the nervous system with a focus on discoveries made using the fruit fly as a model system as well as relevant studies in C elegans, mouse, rat, and cellular models. Since components of this pathway have been implicated in the pathogenesis of numerous psychiatric and neurodegenerative disorders in human, understanding the role of Notch signaling in the mature brain using model organisms will likely provide novel insights into the mechanisms underlying these diseases.
Collapse
Affiliation(s)
- Jose L. Salazar
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; (J.L.S.); (S.-A.Y.)
| | - Sheng-An Yang
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; (J.L.S.); (S.-A.Y.)
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; (J.L.S.); (S.-A.Y.)
- Department of Neuroscience, BCM, Houston, TX 77030, USA
- Program in Developmental Biology, BCM, Houston, TX 77030, USA
- Development, Disease Models & Therapeutics Graduate Program, BCM, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030, USA
- Correspondence: ; Tel.: +1-832-824-8119
| |
Collapse
|
27
|
Mira H, Morante J. Neurogenesis From Embryo to Adult - Lessons From Flies and Mice. Front Cell Dev Biol 2020; 8:533. [PMID: 32695783 PMCID: PMC7339912 DOI: 10.3389/fcell.2020.00533] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/08/2020] [Indexed: 12/30/2022] Open
Abstract
The human brain is composed of billions of cells, including neurons and glia, with an undetermined number of subtypes. During the embryonic and early postnatal stages, the vast majority of these cells are generated from neural progenitors and stem cells located in all regions of the neural tube. A smaller number of neurons will continue to be generated throughout our lives, in localized neurogenic zones, mainly confined at least in rodents to the subependymal zone of the lateral ventricles and the subgranular zone of the hippocampal dentate gyrus. During neurogenesis, a combination of extrinsic cues interacting with temporal and regional intrinsic programs are thought to be critical for increasing neuronal diversity, but their underlying mechanisms need further elucidation. In this review, we discuss the recent findings in Drosophila and mammals on the types of cell division and cell interactions used by neural progenitors and stem cells to sustain neurogenesis, and how they are influenced by glia.
Collapse
Affiliation(s)
- Helena Mira
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Javier Morante
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas y Universidad Miguel Hernandez, Alicante, Spain
| |
Collapse
|
28
|
Hörmann N, Schilling T, Ali AH, Serbe E, Mayer C, Borst A, Pujol-Martí J. A combinatorial code of transcription factors specifies subtypes of visual motion-sensing neurons in Drosophila. Development 2020; 147:223179. [PMID: 32238425 PMCID: PMC7240302 DOI: 10.1242/dev.186296] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/20/2020] [Indexed: 12/21/2022]
Abstract
Direction-selective T4/T5 neurons exist in four subtypes, each tuned to visual motion along one of the four cardinal directions. Along with their directional tuning, neurons of each T4/T5 subtype orient their dendrites and project their axons in a subtype-specific manner. Directional tuning, thus, appears strictly linked to morphology in T4/T5 neurons. How the four T4/T5 subtypes acquire their distinct morphologies during development remains largely unknown. Here, we investigated when and how the dendrites of the four T4/T5 subtypes acquire their specific orientations, and profiled the transcriptomes of all T4/T5 neurons during this process. This revealed a simple and stable combinatorial code of transcription factors defining the four T4/T5 subtypes during their development. Changing the combination of transcription factors of specific T4/T5 subtypes resulted in predictable and complete conversions of subtype-specific properties, i.e. dendrite orientation and matching axon projection pattern. Therefore, a combinatorial code of transcription factors coordinates the development of dendrite and axon morphologies to generate anatomical specializations that differentiate subtypes of T4/T5 motion-sensing neurons. Summary: Morphological and transcriptomic analyses allowed the identification of a combinatorial code of transcription factors that controls the development of subtype-specific morphologies in motion-detecting neurons of the Drosophila visual system.
Collapse
Affiliation(s)
- Nikolai Hörmann
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Tabea Schilling
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Aicha Haji Ali
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Etienne Serbe
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Christian Mayer
- Laboratory of Neurogenomics, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Alexander Borst
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Jesús Pujol-Martí
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| |
Collapse
|
29
|
Chen YC, Desplan C. Gene regulatory networks during the development of the Drosophila visual system. Curr Top Dev Biol 2020; 139:89-125. [PMID: 32450970 DOI: 10.1016/bs.ctdb.2020.02.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The Drosophila visual system integrates input from 800 ommatidia and extracts different features in stereotypically connected optic ganglia. The development of the Drosophila visual system is controlled by gene regulatory networks that control the number of precursor cells, generate neuronal diversity by integrating spatial and temporal information, coordinate the timing of retinal and optic lobe cell differentiation, and determine distinct synaptic targets of each cell type. In this chapter, we describe the known gene regulatory networks involved in the development of the different parts of the visual system and explore general components in these gene networks. Finally, we discuss the advantages of the fly visual system as a model for gene regulatory network discovery in the era of single-cell transcriptomics.
Collapse
Affiliation(s)
- Yen-Chung Chen
- Department of Biology, New York University, New York, NY, United States
| | - Claude Desplan
- Department of Biology, New York University, New York, NY, United States.
| |
Collapse
|
30
|
Agi E, Kulkarni A, Hiesinger PR. Neuronal strategies for meeting the right partner during brain wiring. Curr Opin Neurobiol 2020; 63:1-8. [PMID: 32036252 DOI: 10.1016/j.conb.2020.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/04/2020] [Indexed: 02/07/2023]
Abstract
Two neurons can only form a synapse if their axonal and dendritic projections meet at the same time and place. While spatiotemporal proximity is necessary for synapse formation, it remains unclear to what extent the underlying positional strategies are sufficient to ensure synapse formation between the right partners. Many neurons readily form synapses with wrong partners if they find themselves at the wrong place or time. Minimally, restricting spatiotemporal proximity can prevent incorrect synapses. Maximally, restricting encounters in time and space could be sufficient to ensure correct partnerships between neurons that can form synapses promiscuously. In this review we explore recent findings on positional strategies during developmental growth that contribute to precise outcomes in brain wiring.
Collapse
|
31
|
Caipo L, González-Ramírez MC, Guzmán-Palma P, Contreras EG, Palominos T, Fuenzalida-Uribe N, Hassan BA, Campusano JM, Sierralta J, Oliva C. Slit neuronal secretion coordinates optic lobe morphogenesis in Drosophila. Dev Biol 2020; 458:32-42. [PMID: 31606342 DOI: 10.1016/j.ydbio.2019.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 10/04/2019] [Accepted: 10/05/2019] [Indexed: 12/12/2022]
Abstract
The complexity of the nervous system requires the coordination of multiple cellular processes during development. Among them, we find boundary formation, axon guidance, cell migration and cell segregation. Understanding how different cell populations such as glial cells, developing neurons and neural stem cells contribute to the formation of boundaries and morphogenesis in the nervous system is a critical question in neurobiology. Slit is an evolutionary conserved protein essential for the development of the nervous system. For signaling, Slit has to bind to its cognate receptor Robo, a single-pass transmembrane protein. Although the Slit/Robo signaling pathway is well known for its involvement in axon guidance, it has also been associated to boundary formation in the Drosophila visual system. In the optic lobe, Slit is expressed in glial cells, positioned at the boundaries between developing neuropils, and in neurons of the medulla ganglia. Although it has been assumed that glial cells provide Slit to the system, the contribution of the neuronal expression has not been tested. Here, we show that, contrary to what was previously thought, Slit protein provided by medulla neurons is also required for boundary formation and morphogenesis of the optic lobe. Furthermore, tissue specific rescue using modified versions of Slit demonstrates that this protein acts at long range and does not require processing by extracellular proteases. Our data shed new light on our understanding of the cellular mechanisms involved in Slit function in the fly visual system morphogenesis.
Collapse
Affiliation(s)
- Lorena Caipo
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av Libertador Bernardo O'Higgins 340, Santiago, Chile; Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Independencia 1027, Santiago, Chile
| | - M Constanza González-Ramírez
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av Libertador Bernardo O'Higgins 340, Santiago, Chile
| | - Pablo Guzmán-Palma
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av Libertador Bernardo O'Higgins 340, Santiago, Chile
| | - Esteban G Contreras
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Independencia 1027, Santiago, Chile
| | - Tomás Palominos
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av Libertador Bernardo O'Higgins 340, Santiago, Chile
| | - Nicolás Fuenzalida-Uribe
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av Libertador Bernardo O'Higgins 340, Santiago, Chile
| | - Bassem A Hassan
- Institut du Cerveau et de la Moelle Epinière (ICM) - Sorbonne Université, Hôpital Pitié-Salpêtrière, Inserm, CNRS, Paris, France
| | - Jorge M Campusano
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av Libertador Bernardo O'Higgins 340, Santiago, Chile
| | - Jimena Sierralta
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Independencia 1027, Santiago, Chile
| | - Carlos Oliva
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av Libertador Bernardo O'Higgins 340, Santiago, Chile.
| |
Collapse
|
32
|
Kurmangaliyev YZ, Yoo J, LoCascio SA, Zipursky SL. Modular transcriptional programs separately define axon and dendrite connectivity. eLife 2019; 8:50822. [PMID: 31687928 PMCID: PMC6855804 DOI: 10.7554/elife.50822] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 11/04/2019] [Indexed: 01/31/2023] Open
Abstract
Patterns of synaptic connectivity are remarkably precise and complex. Single-cell RNA sequencing has revealed a vast transcriptional diversity of neurons. Nevertheless, a clear logic underlying the transcriptional control of neuronal connectivity has yet to emerge. Here, we focused on Drosophila T4/T5 neurons, a class of closely related neuronal subtypes with different wiring patterns. Eight subtypes of T4/T5 neurons are defined by combinations of two patterns of dendritic inputs and four patterns of axonal outputs. Single-cell profiling during development revealed distinct transcriptional programs defining each dendrite and axon wiring pattern. These programs were defined by the expression of a few transcription factors and different combinations of cell surface proteins. Gain and loss of function studies provide evidence for independent control of different wiring features. We propose that modular transcriptional programs for distinct wiring features are assembled in different combinations to generate diverse patterns of neuronal connectivity.
Collapse
Affiliation(s)
- Yerbol Z Kurmangaliyev
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Juyoun Yoo
- Neuroscience Interdepartmental Program, University of California, Los Angeles, Los Angeles, United States
| | - Samuel A LoCascio
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - S Lawrence Zipursky
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| |
Collapse
|
33
|
Contreras EG, Sierralta J, Oliva C. Novel Strategies for the Generation of Neuronal Diversity: Lessons From the Fly Visual System. Front Mol Neurosci 2019; 12:140. [PMID: 31213980 PMCID: PMC6554424 DOI: 10.3389/fnmol.2019.00140] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 05/13/2019] [Indexed: 12/17/2022] Open
Abstract
Among all organs of an adult animal, the central nervous system stands out because of its vast complexity and morphological diversity. During early development, the entire central nervous system develops from an apparently homogenous group of progenitors that differentiate into all neural cell types. Therefore, understanding the molecular and genetic mechanisms that give rise to the cellular and anatomical diversity of the brain is a key goal of the developmental neurobiology field. With this aim in mind, the development of the central nervous system of model organisms has been extensively studied. From more than a century, the mechanisms of neurogenesis have been studied in the fruit fly Drosophila melanogaster. The visual system comprises one of the major structures of the Drosophila brain. The visual information is collected by the eye-retina photoreceptors and then processed by the four optic lobe ganglia: the lamina, medulla, lobula and lobula plate. The molecular mechanisms that originate neuronal diversity in the optic lobe have been unveiled in the past decade. In this article, we describe the early development and differentiation of the lobula plate ganglion, from the formation of the optic placode and the inner proliferation center to the specification of motion detection neurons. We focused specifically on how the precise combination of signaling pathways and cell-specific transcription factors patterns the pool of neural stem cells that generates the different neurons of the motion detection system.
Collapse
Affiliation(s)
- Esteban G Contreras
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Jimena Sierralta
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Carlos Oliva
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| |
Collapse
|
34
|
Sullivan LF. Rewiring the Drosophila Brain With Genetic Manipulations in Neural Lineages. Front Mol Neurosci 2019; 12:82. [PMID: 31019451 PMCID: PMC6458239 DOI: 10.3389/fnmol.2019.00082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 03/14/2019] [Indexed: 11/13/2022] Open
Abstract
Neurons originate from neural stem cells and then synapse with stereotyped partners to form neuronal circuits. Recent findings indicate that several molecular mechanisms generating neuronal identity can rewire neuronal connectivity in the Drosophila brain when genetically manipulated. In this review, I discuss how mechanisms generating neuronal identity could activate molecular pathways essential for circuit formation and function. Next, I propose that the central complex of Drosophila, an ancient and highly conserved brain region essential for locomotor control and navigation, is an excellent model system to further explore mechanisms linking circuit development to circuit function.
Collapse
Affiliation(s)
- Luis F Sullivan
- Institute of Neuroscience, University of Oregon, Eugene, OR, United States
| |
Collapse
|
35
|
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.
Collapse
|
36
|
Schilling T, Ali AH, Leonhardt A, Borst A, Pujol-Martí J. Transcriptional control of morphological properties of direction-selective T4/T5 neurons in Drosophila. Development 2019; 146:dev169763. [PMID: 30642835 PMCID: PMC6361130 DOI: 10.1242/dev.169763] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 01/07/2019] [Indexed: 02/02/2023]
Abstract
In the Drosophila visual system, T4/T5 neurons represent the first stage of computation of the direction of visual motion. T4 and T5 neurons exist in four subtypes, each responding to motion in one of the four cardinal directions and projecting axons into one of the four lobula plate layers. However, all T4/T5 neurons share properties essential for sensing motion. How T4/T5 neurons acquire their properties during development is poorly understood. We reveal that the transcription factors SoxN and Sox102F control the acquisition of properties common to all T4/T5 neuron subtypes, i.e. the layer specificity of dendrites and axons. Accordingly, adult flies are motion blind after disruption of SoxN or Sox102F in maturing T4/T5 neurons. We further find that the transcription factors Ato and Dac are redundantly required in T4/T5 neuron progenitors for SoxN and Sox102F expression in T4/T5 neurons, linking the transcriptional programmes specifying progenitor identity to those regulating the acquisition of morphological properties in neurons. Our work will help to link structure, function and development in a neuronal type performing a computation that is conserved across vertebrate and invertebrate visual systems.
Collapse
Affiliation(s)
- Tabea Schilling
- Department of 'Circuits - Computation - Models', Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Aicha H Ali
- Department of 'Circuits - Computation - Models', Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Aljoscha Leonhardt
- Department of 'Circuits - Computation - Models', Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Alexander Borst
- Department of 'Circuits - Computation - Models', Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Jesús Pujol-Martí
- Department of 'Circuits - Computation - Models', Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| |
Collapse
|
37
|
Yoon KJ, Ming GL, Song H. Coupling Neurogenesis to Circuit Formation. Cell 2019; 173:288-290. [PMID: 29625047 DOI: 10.1016/j.cell.2018.03.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A central question in neuroscience is how developmental programs instruct the formation of complex neural circuits with temporal, spatial, and numerical precision. Pinto-Teixeira et al. (2018) reveal simple developmental rules that govern sequential neurogenesis to concurrently establish highly organized retinotopic maps in the Drosophila visual system.
Collapse
Affiliation(s)
- Ki-Jun Yoon
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Guo-Li Ming
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hongjun Song
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; The Epigenetics Institute, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| |
Collapse
|
38
|
Shinomiya K, Huang G, Lu Z, Parag T, Xu CS, Aniceto R, Ansari N, Cheatham N, Lauchie S, Neace E, Ogundeyi O, Ordish C, Peel D, Shinomiya A, Smith C, Takemura S, Talebi I, Rivlin PK, Nern A, Scheffer LK, Plaza SM, Meinertzhagen IA. Comparisons between the ON- and OFF-edge motion pathways in the Drosophila brain. eLife 2019; 8:40025. [PMID: 30624205 PMCID: PMC6338461 DOI: 10.7554/elife.40025] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 01/02/2019] [Indexed: 02/03/2023] Open
Abstract
Understanding the circuit mechanisms behind motion detection is a long-standing question in visual neuroscience. In Drosophila melanogaster, recently discovered synapse-level connectomes in the optic lobe, particularly in ON-pathway (T4) receptive-field circuits, in concert with physiological studies, suggest a motion model that is increasingly intricate when compared with the ubiquitous Hassenstein-Reichardt model. By contrast, our knowledge of OFF-pathway (T5) has been incomplete. Here, we present a conclusive and comprehensive connectome that, for the first time, integrates detailed connectivity information for inputs to both the T4 and T5 pathways in a single EM dataset covering the entire optic lobe. With novel reconstruction methods using automated synapse prediction suited to such a large connectome, we successfully corroborate previous findings in the T4 pathway and comprehensively identify inputs and receptive fields for T5. Although the two pathways are probably evolutionarily linked and exhibit many similarities, we uncover interesting differences and interactions that may underlie their distinct functional properties.
Collapse
Affiliation(s)
- Kazunori Shinomiya
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Gary Huang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Zhiyuan Lu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States.,Department of Psychology and Neuroscience, Dalhousie University, Halifax, Canada
| | - Toufiq Parag
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States.,School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
| | - C Shan Xu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Roxanne Aniceto
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Namra Ansari
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Natasha Cheatham
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Shirley Lauchie
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Erika Neace
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Omotara Ogundeyi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Christopher Ordish
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - David Peel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Aya Shinomiya
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Claire Smith
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Satoko Takemura
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Iris Talebi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Patricia K Rivlin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Aljoscha Nern
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Louis K Scheffer
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Stephen M Plaza
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Ian A Meinertzhagen
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, Canada
| |
Collapse
|
39
|
Abstract
To understand how neurons assemble to form functional circuits, it is necessary to obtain a detailed knowledge of their diversity and to define the developmental specification programs that give rise to this diversity. Invertebrates and vertebrates appear to share common developmental principles of neuronal specification in which cascades of transcription factors temporally pattern progenitors, while spatial cues modify the outcomes of this temporal patterning. Here, we highlight these conserved mechanisms and describe how they are used in distinct neural structures. We present the questions that remain for a better understanding of neuronal specification. Single-cell RNA profiling approaches will potentially shed light on these questions, allowing not only the characterization of neuronal diversity in adult brains, but also the investigation of the developmental trajectories leading to the generation and maintenance of this diversity.
Collapse
Affiliation(s)
- Isabel Holguera
- Department of Biology, New York University, New York, NY 10003, USA
| | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA. .,Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| |
Collapse
|
40
|
Miyares RL, Lee T. Temporal control of Drosophila central nervous system development. Curr Opin Neurobiol 2018; 56:24-32. [PMID: 30500514 DOI: 10.1016/j.conb.2018.10.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 10/30/2018] [Indexed: 12/19/2022]
Abstract
A complex nervous system requires precise numbers of various neuronal types produced with exquisite spatiotemporal control. This striking diversity is generated by a limited number of neural stem cells (NSC), where spatial and temporal patterning intersect. Drosophila is a genetically tractable model system that has significant advantages for studying stem cell biology and neuronal fate specification. Here we review the latest findings in the rich literature of temporal patterning of neuronal identity in the Drosophila central nervous system. Rapidly changing consecutive transcription factors expressed in NSCs specify short series of neurons with considerable differences. More slowly progressing changes are orchestrated by NSC intrinsic temporal factor gradients which integrate extrinsic signals to coordinate nervous system and organismal development.
Collapse
Affiliation(s)
- Rosa Linda Miyares
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Tzumin Lee
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA.
| |
Collapse
|
41
|
Sato M, Yasugi T, Trush O. Temporal patterning of neurogenesis and neural wiring in the fly visual system. Neurosci Res 2018; 138:49-58. [PMID: 30227165 DOI: 10.1016/j.neures.2018.09.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 08/13/2018] [Accepted: 08/13/2018] [Indexed: 12/21/2022]
Abstract
During neural development, a wide variety of neurons are produced in a highly coordinated manner and form complex and highly coordinated neural circuits. Temporal patterning of neuron type specification plays very important roles in orchestrating the production and wiring of neurons. The fly visual system, which is composed of the retina and the optic lobe of the brain, is an outstanding model system to study temporal patterning and wiring of the nervous system. All of the components of the fly visual system are topographically connected, and each ommatidial unit in the retina corresponds to a columnar unit in the optic lobe. In the retina, the wave of differentiation follows the morphogenetic furrow, which progresses in a posterior-to-anterior direction. At the same time, differentiation of the optic lobe also accompanies the wave of differentiation or temporally coordinated neurogenesis. Thus, temporal patterning plays important roles in establishing topographic connections throughout the fly visual system. In this article, we review how neuronal differentiation and connectivity are orchestrated in the fly visual system by temporal patterning mechanisms.
Collapse
Affiliation(s)
- Makoto Sato
- Mathematical Neuroscience Unit, Institute for Frontier Science Initiative, Japan; Lab of Developmental Neurobiology, Graduate School of Medical Sciences, Kanazawa University, Japan.
| | - Tetsuo Yasugi
- Mathematical Neuroscience Unit, Institute for Frontier Science Initiative, Japan
| | - Olena Trush
- Lab of Developmental Neurobiology, Graduate School of Medical Sciences, Kanazawa University, Japan
| |
Collapse
|
42
|
Contreras EG, Palominos T, Glavic Á, Brand AH, Sierralta J, Oliva C. The transcription factor SoxD controls neuronal guidance in the Drosophila visual system. Sci Rep 2018; 8:13332. [PMID: 30190506 PMCID: PMC6127262 DOI: 10.1038/s41598-018-31654-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 08/23/2018] [Indexed: 01/21/2023] Open
Abstract
Precise control of neurite guidance during development is essential to ensure proper formation of neuronal networks and correct function of the central nervous system (CNS). How neuronal projections find their targets to generate appropriate synapses is not entirely understood. Although transcription factors are key molecules during neurogenesis, we do not know their entire function during the formation of networks in the CNS. Here, we used the Drosophila melanogaster optic lobe as a model for understanding neurite guidance during development. We assessed the function of Sox102F/SoxD, the unique Drosophila orthologue of the vertebrate SoxD family of transcription factors. SoxD is expressed in immature and mature neurons in the larval and adult lobula plate ganglia (one of the optic lobe neuropils), but is absent from glial cells, neural stem cells and progenitors of the lobula plate. SoxD RNAi knockdown in all neurons results in a reduction of the lobula plate neuropil, without affecting neuronal fate. This morphological defect is associated with an impaired optomotor response of adult flies. Moreover, knocking down SoxD only in T4/T5 neuronal types, which control motion vision, affects proper neurite guidance into the medulla and lobula. Our findings suggest that SoxD regulates neurite guidance, without affecting neuronal fate.
Collapse
Affiliation(s)
- Esteban G Contreras
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Independencia, 1027, Santiago, Chile.,Center for Genome Regulation, Faculty of Sciences, Universidad de Chile, Las Palmeras, 3425, Nuñoa, Santiago, Chile
| | - Tomás Palominos
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av Libertador Bernardo O'Higgins 340, Santiago, Chile
| | - Álvaro Glavic
- Center for Genome Regulation, Faculty of Sciences, Universidad de Chile, Las Palmeras, 3425, Nuñoa, Santiago, Chile
| | - Andrea H Brand
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, United Kingdom
| | - Jimena Sierralta
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Independencia, 1027, Santiago, Chile
| | - Carlos Oliva
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av Libertador Bernardo O'Higgins 340, Santiago, Chile.
| |
Collapse
|
43
|
Li B, Wong C, Gao SM, Zhang R, Sun R, Li Y, Song Y. The retromer complex safeguards against neural progenitor-derived tumorigenesis by regulating Notch receptor trafficking. eLife 2018; 7:38181. [PMID: 30176986 PMCID: PMC6140715 DOI: 10.7554/elife.38181] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 08/17/2018] [Indexed: 12/14/2022] Open
Abstract
The correct establishment and maintenance of unidirectional Notch signaling are critical for the homeostasis of various stem cell lineages. However, the molecular mechanisms that prevent cell-autonomous ectopic Notch signaling activation and deleterious cell fate decisions remain unclear. Here we show that the retromer complex directly and specifically regulates Notch receptor retrograde trafficking in Drosophila neuroblast lineages to ensure the unidirectional Notch signaling from neural progenitors to neuroblasts. Notch polyubiquitination mediated by E3 ubiquitin ligase Itch/Su(dx) is inherently inefficient within neural progenitors, relying on retromer-mediated trafficking to avoid aberrant endosomal accumulation of Notch and cell-autonomous signaling activation. Upon retromer dysfunction, hypo-ubiquitinated Notch accumulates in Rab7+ enlarged endosomes, where it is ectopically processed and activated in a ligand-dependent manner, causing progenitor-originated tumorigenesis. Our results therefore unveil a safeguard mechanism whereby retromer retrieves potentially harmful Notch receptors in a timely manner to prevent aberrant Notch activation-induced neural progenitor dedifferentiation and brain tumor formation. Most cells in the animal body are tailored to perform particular tasks, but stem cells have not yet made their choice. Instead, they have unlimited capacity to divide and, with the right signals, they can start to specialize to become a given type of cells. In the brain, this process starts with a stem cell dividing. One of the daughters will remain a stem cell, while the other, the neural progenitor, will differentiate to form a mature cell such as a neuron. Keeping this tight balance is crucial for the health of the organ: if the progenitor reverts back to being a stem cell, there will be a surplus of undifferentiated cells that can lead to a tumor. A one-way signal driven by the protein Notch partly controls the distinct fates of the two daughter cells. While the neural progenitor carries Notch at its surface, its neural stem cell sister has a Notch receptor on its membrane instead. This ensures that the Notch signaling goes in one direction, from the cell with Notch to the one sporting the receptor. When a stem cell divides, one daughter gets more of a protein called Numb than the other. Numb pulls Notch receptors away from the external membrane and into internal capsules called endosomes. This guarantees that only one of the siblings will be carrying the receptors at its surface. Yet, sometimes the Notch receptors can get activated in the endosomes, which may make neural progenitors revert to being stem cells. It is still unclear what tools the cells have to stop this abnormal activation. Here, Li et al. screened brain cells from fruit fly larvae to find out the genes that might play a role in suppressing the inappropriate Notch signaling. This highlighted a protein complex known as the retromer, which normally helps to transport proteins in the cell. Experiments showed that, in progenitors, the retromer physically interacts with Notch receptors and retrieves them from the endosomes back to the cell surface. If the retromer is inactive, the Notch receptors accumulate in the endosomes, where they can be switched on. It seems that, in fruit flies, the retromer acts as a bomb squad that recognizes and retrieves potentially harmful Notch receptors, thereby preventing brain tumor formation. Several retromer components are less present in patients with various cancers, including glioblastoma, an aggressive form of brain cancer. The results by Li et al. may therefore shed light on the link between the protein complex and the emergence of the disease in humans.
Collapse
Affiliation(s)
- Bo Li
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China
| | - Chouin Wong
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China
| | - Shihong Max Gao
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China
| | - Rulan Zhang
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China
| | - Rongbo Sun
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Yan Song
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| |
Collapse
|
44
|
Developmental Biology: Neurons That Divide Together Wire Together. Curr Biol 2018; 28:R715-R717. [PMID: 29920268 DOI: 10.1016/j.cub.2018.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Retinotopic maps represent a fundamental organizing principle of visual system wiring. A recent study illustrates how careful coordination of developmental strategies can simultaneously create a diverse array of cell types and establish a complex wiring diagram.
Collapse
|
45
|
Apitz H, Salecker I. Spatio-temporal relays control layer identity of direction-selective neuron subtypes in Drosophila. Nat Commun 2018; 9:2295. [PMID: 29895891 PMCID: PMC5997761 DOI: 10.1038/s41467-018-04592-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 05/04/2018] [Indexed: 11/09/2022] Open
Abstract
Visual motion detection in sighted animals is essential to guide behavioral actions ensuring their survival. In Drosophila, motion direction is first detected by T4/T5 neurons. Their axons innervate one of the four lobula plate layers. How T4/T5 neurons with layer-specific representation of motion-direction preferences are specified during development is unknown. We show that diffusible Wingless (Wg) between adjacent neuroepithelia induces its own expression to form secondary signaling centers. These activate Decapentaplegic (Dpp) signaling in adjacent lateral tertiary neuroepithelial domains dedicated to producing layer 3/4-specific T4/T5 neurons. T4/T5 neurons derived from the core domain devoid of Dpp signaling adopt the default layer 1/2 fate. Dpp signaling induces the expression of the T-box transcription factor Optomotor-blind (Omb), serving as a relay to postmitotic neurons. Omb-mediated repression of Dachshund transforms layer 1/2- into layer 3/4-specific neurons. Hence, spatio-temporal relay mechanisms, bridging the distances between neuroepithelial domains and their postmitotic progeny, implement T4/T5 neuron-subtype identity.
Collapse
Affiliation(s)
- Holger Apitz
- The Francis Crick Institute, Visual Circuit Assembly Laboratory, 1 Midland Road, London, NW1 1AT, UK
| | - Iris Salecker
- The Francis Crick Institute, Visual Circuit Assembly Laboratory, 1 Midland Road, London, NW1 1AT, UK.
| |
Collapse
|
46
|
Homan CC, Pederson S, To TH, Tan C, Piltz S, Corbett MA, Wolvetang E, Thomas PQ, Jolly LA, Gecz J. PCDH19 regulation of neural progenitor cell differentiation suggests asynchrony of neurogenesis as a mechanism contributing to PCDH19 Girls Clustering Epilepsy. Neurobiol Dis 2018; 116:106-119. [PMID: 29763708 DOI: 10.1016/j.nbd.2018.05.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/25/2018] [Accepted: 05/09/2018] [Indexed: 01/12/2023] Open
Abstract
PCDH19-Girls Clustering Epilepsy (PCDH19-GCE) is a childhood epileptic encephalopathy characterised by a spectrum of neurodevelopmental problems. PCDH19-GCE is caused by heterozygous loss-of-function mutations in the X-chromosome gene, Protocadherin 19 (PCDH19) encoding a cell-cell adhesion molecule. Intriguingly, hemizygous males are generally unaffected. As PCDH19 is subjected to random X-inactivation, heterozygous females are comprised of a mosaic of cells expressing either the normal or mutant allele, which is thought to drive pathology. Despite being the second most prevalent monogeneic cause of epilepsy, little is known about the role of PCDH19 in brain development. In this study we show that PCDH19 is highly expressed in human neural stem and progenitor cells (NSPCs) and investigate its function in vitro in these cells of both mouse and human origin. Transcriptomic analysis of mouse NSPCs lacking Pcdh19 revealed changes to genes involved in regulation of neuronal differentiation, and we subsequently show that loss of Pcdh19 causes increased NSPC neurogenesis. We reprogramed human fibroblast cells harbouring a pathogenic PCDH19 mutation into human induced pluripotent stem cells (hiPSC) and employed neural differentiation of these to extend our studies into human NSPCs. As in mouse, loss of PCDH19 function caused increased neurogenesis, and furthermore, we show this is associated with a loss of human NSPC polarity. Overall our data suggests a conserved role for PCDH19 in regulating mammalian cortical neurogenesis and has implications for the pathogenesis of PCDH19-GCE. We propose that the difference in timing or "heterochrony" of neuronal cell production originating from PCDH19 wildtype and mutant NSPCs within the same individual may lead to downstream asynchronies and abnormalities in neuronal network formation, which in-part predispose the individual to network dysfunction and epileptic activity.
Collapse
Affiliation(s)
- Claire C Homan
- School of Medicine, The University of Adelaide, Adelaide 5005, Australia; Robinson Research Institute, The University of Adelaide, Adelaide 5006, Australia; School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia
| | - Stephen Pederson
- Bioinformatics Hub, School of Biological Sciences, The University of Adelaide, Adelaide, 5005, Australia
| | - Thu-Hien To
- Bioinformatics Hub, School of Biological Sciences, The University of Adelaide, Adelaide, 5005, Australia
| | - Chuan Tan
- School of Medicine, The University of Adelaide, Adelaide 5005, Australia; Robinson Research Institute, The University of Adelaide, Adelaide 5006, Australia
| | - Sandra Piltz
- Robinson Research Institute, The University of Adelaide, Adelaide 5006, Australia; School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia; South Australian Health and Medical Research Institute, Adelaide 5000, Australia
| | - Mark A Corbett
- School of Medicine, The University of Adelaide, Adelaide 5005, Australia; Robinson Research Institute, The University of Adelaide, Adelaide 5006, Australia; School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia
| | - Ernst Wolvetang
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Queensland 4072, Australia
| | - Paul Q Thomas
- Robinson Research Institute, The University of Adelaide, Adelaide 5006, Australia; School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia; South Australian Health and Medical Research Institute, Adelaide 5000, Australia
| | - Lachlan A Jolly
- School of Medicine, The University of Adelaide, Adelaide 5005, Australia; Robinson Research Institute, The University of Adelaide, Adelaide 5006, Australia.
| | - Jozef Gecz
- School of Medicine, The University of Adelaide, Adelaide 5005, Australia; Robinson Research Institute, The University of Adelaide, Adelaide 5006, Australia; School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia; South Australian Health and Medical Research Institute, Adelaide 5000, Australia.
| |
Collapse
|
47
|
Mora N, Oliva C, Fiers M, Ejsmont R, Soldano A, Zhang TT, Yan J, Claeys A, De Geest N, Hassan BA. A Temporal Transcriptional Switch Governs Stem Cell Division, Neuronal Numbers, and Maintenance of Differentiation. Dev Cell 2018; 45:53-66.e5. [DOI: 10.1016/j.devcel.2018.02.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 02/12/2018] [Accepted: 02/26/2018] [Indexed: 01/06/2023]
|