1
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Ricquebourg R, Konstantinides N. [A temporal mechanism for the generation of neuronal diversity]. Med Sci (Paris) 2024; 40:251-257. [PMID: 38520100 DOI: 10.1051/medsci/2024012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2024] Open
Abstract
One of the greatest challenges in neuroscience is to understand how a complex structure, such as the brain, is built. Spatial and temporal patternings of neuronal progenitors are responsible for the generation of most of the neuronal diversity observed in the brain. This review focuses on the temporal patterning of neuronal progenitors, i.e. the sequential expression of transcription factors that changes the capacity of stem cells to generate different neuronal types, and which is conserved in animals. Recent papers have offered a near complete understanding of the mechanism of temporal patterning in the developing visual system of Drosophila, and of how this contributes to the specification of diverse neuronal identities, which are then maintained by the sustained expression of downstream transcription factors. The insect visual system provides a unique model to study the evolution of neuronal cell types, as well as the evolution of neurodevelopmental mechanisms that generate them.
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2
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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.
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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
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3
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Zhang X, Leavey P, Appel H, Makrides N, Blackshaw S. Molecular mechanisms controlling vertebrate retinal patterning, neurogenesis, and cell fate specification. Trends Genet 2023; 39:736-757. [PMID: 37423870 PMCID: PMC10529299 DOI: 10.1016/j.tig.2023.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 07/11/2023]
Abstract
This review covers recent advances in understanding the molecular mechanisms controlling neurogenesis and specification of the developing retina, with a focus on insights obtained from comparative single cell multiomic analysis. We discuss recent advances in understanding the mechanisms by which extrinsic factors trigger transcriptional changes that spatially pattern the optic cup (OC) and control the initiation and progression of retinal neurogenesis. We also discuss progress in unraveling the core evolutionarily conserved gene regulatory networks (GRNs) that specify early- and late-state retinal progenitor cells (RPCs) and neurogenic progenitors and that control the final steps in determining cell identity. Finally, we discuss findings that provide insight into regulation of species-specific aspects of retinal patterning and neurogenesis, including consideration of key outstanding questions in the field.
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Affiliation(s)
- Xin Zhang
- Department of Ophthalmology, Columbia University School of Medicine, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University School of Medicine, New York, NY, USA.
| | - Patrick Leavey
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Haley Appel
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Neoklis Makrides
- Department of Ophthalmology, Columbia University School of Medicine, New York, NY, USA
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Psychiatry and Behavioral Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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4
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El-Danaf RN, Rajesh R, Desplan C. Temporal regulation of neural diversity in Drosophila and vertebrates. Semin Cell Dev Biol 2023; 142:13-22. [PMID: 35623984 DOI: 10.1016/j.semcdb.2022.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 05/11/2022] [Accepted: 05/16/2022] [Indexed: 10/18/2022]
Abstract
The generation of neuronal diversity involves temporal patterning mechanisms by which a given progenitor sequentially produces multiple cell types. Several parallels are evident between the brain development programs of Drosophila and vertebrates, such as the successive emergence of specific cell types and the use of combinations of transcription factors to specify cell fates. Furthermore, cell-extrinsic cues such as hormones and signaling pathways have also been shown to be regulatory modules of temporal patterning. Recently, transcriptomic and epigenomic studies using large single-cell sequencing datasets have provided insights into the transcriptional dynamics of neurogenesis in the Drosophila and mammalian central nervous systems. We review these commonalities in the specification of neuronal identity and highlight the conserved or convergent strategies of brain development by discussing temporal patterning mechanisms found in flies and vertebrates.
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Affiliation(s)
- Rana N El-Danaf
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.
| | - Raghuvanshi Rajesh
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Claude Desplan
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, Abu Dhabi, United Arab Emirates; Department of Biology, New York University, New York, NY 10003, USA.
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5
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Zhang J, Roberts JM, Chang F, Schwakopf J, Vetter ML. Jarid2 promotes temporal progression of retinal progenitors via repression of Foxp1. Cell Rep 2023; 42:112237. [PMID: 36924502 PMCID: PMC10210259 DOI: 10.1016/j.celrep.2023.112237] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 01/14/2023] [Accepted: 02/24/2023] [Indexed: 03/16/2023] Open
Abstract
Transitions in competence underlie the ability of CNS progenitors to generate a diversity of neurons and glia. Retinal progenitor cells in mouse generate early-born cell types embryonically and late-born cell types largely postnatally. We find that the transition from early to late progenitor competence is regulated by Jarid2. Loss of Jarid2 results in extended production of early cell types and extended expression of early progenitor genes. Jarid2 can regulate histone modifications, and we find reduction of repressive mark H3K27me3 on a subset of early progenitor genes with loss of Jarid2, most notably Foxp1. We show that Foxp1 regulates the competence to generate early-born retinal cell types, promotes early and represses late progenitor gene expression, and is required for extending early retinal cell production after loss of Jarid2. We conclude that Jarid2 facilitates progression of retinal progenitor temporal identity by repressing Foxp1, which is a primary regulator of early temporal patterning.
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Affiliation(s)
- Jianmin Zhang
- Department of Neurobiology, University of Utah Spencer Fox Eccles School of Medicine, Salt Lake City, UT 84112, USA
| | - Jacqueline M Roberts
- Department of Neurobiology, University of Utah Spencer Fox Eccles School of Medicine, Salt Lake City, UT 84112, USA
| | - Fei Chang
- Department of Neurobiology, University of Utah Spencer Fox Eccles School of Medicine, Salt Lake City, UT 84112, USA; Interdepartmental Program in Neuroscience, University of Utah Spencer Fox Eccles School of Medicine, Salt Lake City, UT 84112, USA
| | - Joon Schwakopf
- Department of Neurobiology, University of Utah Spencer Fox Eccles School of Medicine, Salt Lake City, UT 84112, USA
| | - Monica L Vetter
- Department of Neurobiology, University of Utah Spencer Fox Eccles School of Medicine, Salt Lake City, UT 84112, USA.
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6
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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.
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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
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7
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Slavi N, Balasubramanian R, Lee MA, Liapin M, Oaks-Leaf R, Peregrin J, Potenski A, Troy CM, Ross ME, Herrera E, Kosmidis S, John SWM, Mason CA. CyclinD2-mediated regulation of neurogenic output from the retinal ciliary margin is perturbed in albinism. Neuron 2023; 111:49-64.e5. [PMID: 36351424 PMCID: PMC9822872 DOI: 10.1016/j.neuron.2022.10.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 09/28/2022] [Accepted: 10/10/2022] [Indexed: 11/09/2022]
Abstract
In albinism, aberrations in the ipsi-/contralateral retinal ganglion cell (RGC) ratio compromise the functional integrity of the binocular circuit. Here, we focus on the mouse ciliary margin zone (CMZ), a neurogenic niche at the embryonic peripheral retina, to investigate developmental processes regulating RGC neurogenesis and identity acquisition. We found that the mouse ventral CMZ generates predominantly ipsilaterally projecting RGCs, but this output is altered in the albino visual system because of CyclinD2 downregulation and disturbed timing of the cell cycle. Consequently, albino as well as CyclinD2-deficient pigmented mice exhibit diminished ipsilateral retinogeniculate projection and poor depth perception. In albino mice, pharmacological stimulation of calcium channels, known to upregulate CyclinD2 in other cell types, augmented CyclinD2-dependent neurogenesis of ipsilateral RGCs and improved stereopsis. Together, these results implicate CMZ neurogenesis and its regulators as critical for the formation and function of the mammalian binocular circuit.
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Affiliation(s)
- Nefeli Slavi
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA.
| | - Revathi Balasubramanian
- Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Melissa Ann Lee
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Michael Liapin
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Rachel Oaks-Leaf
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - John Peregrin
- Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Anna Potenski
- Department of Molecular Pharmacology and Therapeutics, Columbia University, College of Physicians and Surgeons, New York, NY, USA
| | - Carol Marie Troy
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA; The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Margaret Elizabeth Ross
- Center for Neurogenetics, Feil Family Brain & Mind Research Institute, Weill Cornell Medical College, New York, NY, USA
| | - Eloisa Herrera
- Instituto de Neurociencias (CSIC-UMH), Av. Ramón y Cajal s/n, San Juan de Alicante, Spain
| | - Stylianos Kosmidis
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Simon William Maxwell John
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA; Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Carol Ann Mason
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA; Department of Neuroscience, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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8
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A Spacetime Odyssey of Neural Progenitors to Generate Neuronal Diversity. Neurosci Bull 2022; 39:645-658. [PMID: 36214963 PMCID: PMC10073374 DOI: 10.1007/s12264-022-00956-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 06/29/2022] [Indexed: 10/17/2022] Open
Abstract
To understand how the nervous system develops from a small pool of progenitors during early embryonic development, it is fundamentally important to identify the diversity of neuronal subtypes, decode the origin of neuronal diversity, and uncover the principles governing neuronal specification across different regions. Recent single-cell analyses have systematically identified neuronal diversity at unprecedented scale and speed, leaving the deconstruction of spatiotemporal mechanisms for generating neuronal diversity an imperative and paramount challenge. In this review, we highlight three distinct strategies deployed by neural progenitors to produce diverse neuronal subtypes, including predetermined, stochastic, and cascade diversifying models, and elaborate how these strategies are implemented in distinct regions such as the neocortex, spinal cord, retina, and hypothalamus. Importantly, the identity of neural progenitors is defined by their spatial position and temporal patterning factors, and each type of progenitor cell gives rise to distinguishable cohorts of neuronal subtypes. Microenvironmental cues, spontaneous activity, and connectional pattern further reshape and diversify the fate of unspecialized neurons in particular regions. The illumination of how neuronal diversity is generated will pave the way for producing specific brain organoids to model human disease and desired neuronal subtypes for cell therapy, as well as understanding the organization of functional neural circuits and the evolution of the nervous system.
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9
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Jin M, Zhang H, Xu B, Li Y, Qin H, Yu S, He J. Jag2b-Notch3/1b-mediated neuron-to-glia crosstalk controls retinal gliogenesis. EMBO Rep 2022; 23:e54922. [PMID: 36047082 PMCID: PMC9535768 DOI: 10.15252/embr.202254922] [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: 02/23/2022] [Revised: 08/03/2022] [Accepted: 08/18/2022] [Indexed: 11/09/2022] Open
Abstract
In the developing central nervous systems (CNS), neural progenitor cells generate neurons and glia in sequential order. However, the influence of neurons on glia generation remains elusive. Here, we report that photoreceptor cell-derived Jag2b is required for Notch-dependent Müller glia (MG) generation in the developing zebrafish retina. In jab2b-/- mutants, differentiating MGs are re-specified into lineage-related bipolar neuron fate at the expense of mature MG. Single-cell transcriptome analysis and knock-in animals reveal that jab2b is specifically expressed in crx+ -photoreceptor cells during MG generation. Crx promoter-driven jag2b, but not other Notch ligands, is sufficient to rescue the loss of MGs observed in jag2b-/- mutants. Furthermore, we observe a severe and moderate decrease in the number of MGs in notch3-/- and notch1b-/- mutants, respectively, and the activation of Notch3 or Notch1b rescues the MG loss in jag2b-/- mutants. Together, our findings reveal that the interaction of Jag2b and Notch3/Notch1b mediates the crosstalk between neurons and glial cells to ensure the irreversible differentiation of MG, providing novel mechanistic insights into the temporal specification of glial cell fate in a developing vertebrate CNS structure.
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Affiliation(s)
- Mengmeng Jin
- State Key Laboratory of NeuroscienceInstitute of NeuroscienceCenter for Excellence in Brain Science and Intelligence TechnologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Hui Zhang
- State Key Laboratory of NeuroscienceInstitute of NeuroscienceCenter for Excellence in Brain Science and Intelligence TechnologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Baijie Xu
- State Key Laboratory of NeuroscienceInstitute of NeuroscienceCenter for Excellence in Brain Science and Intelligence TechnologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Yanan Li
- State Key Laboratory of NeuroscienceInstitute of NeuroscienceCenter for Excellence in Brain Science and Intelligence TechnologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Huiwen Qin
- State Key Laboratory of NeuroscienceInstitute of NeuroscienceCenter for Excellence in Brain Science and Intelligence TechnologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Shuguang Yu
- State Key Laboratory of NeuroscienceInstitute of NeuroscienceCenter for Excellence in Brain Science and Intelligence TechnologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Jie He
- State Key Laboratory of NeuroscienceInstitute of NeuroscienceCenter for Excellence in Brain Science and Intelligence TechnologyChinese Academy of SciencesShanghaiChina
- Shanghai Center for Brain Science and Brain‐Inspired Intelligence TechnologyShanghaiChina
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10
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Cobham AE, Neumann B, Mirth CK. Maintaining robust size across environmental conditions through plastic brain growth dynamics. Open Biol 2022; 12:220037. [PMID: 36102061 PMCID: PMC9471992 DOI: 10.1098/rsob.220037] [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] [Indexed: 11/30/2022] Open
Abstract
Organ growth is tightly regulated across environmental conditions to generate an appropriate final size. While the size of some organs is free to vary, others need to maintain constant size to function properly. This poses a unique problem: how is robust final size achieved when environmental conditions alter key processes that regulate organ size throughout the body, such as growth rate and growth duration? While we know that brain growth is ‘spared’ from the effects of the environment from humans to fruit flies, we do not understand how this process alters growth dynamics across brain compartments. Here, we explore how this robustness in brain size is achieved by examining differences in growth patterns between the larval body, the brain and a brain compartment—the mushroom bodies—in Drosophila melanogaster across both thermal and nutritional conditions. We identify key differences in patterns of growth between the whole brain and mushroom bodies that are likely to underlie robustness of final organ shape. Further, we show that these differences produce distinct brain shapes across environments.
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Affiliation(s)
- Ansa E Cobham
- School of Biological Sciences, Monash University, Melbourne, Australia
| | - Brent Neumann
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Christen K Mirth
- School of Biological Sciences, Monash University, Melbourne, Australia
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11
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Melillo R, Leisman G, Machado C, Machado-Ferrer Y, Chinchilla-Acosta M, Kamgang S, Melillo T, Carmeli E. Retained Primitive Reflexes and Potential for Intervention in Autistic Spectrum Disorders. Front Neurol 2022; 13:922322. [PMID: 35873782 PMCID: PMC9301367 DOI: 10.3389/fneur.2022.922322] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 06/06/2022] [Indexed: 11/13/2022] Open
Abstract
We provide evidence to support the contention that many aspects of Autistic Spectrum Disorder (ASD) are related to interregional brain functional disconnectivity associated with maturational delays in the development of brain networks. We think a delay in brain maturation in some networks may result in an increase in cortical maturation and development in other networks, leading to a developmental asynchrony and an unevenness of functional skills and symptoms. The paper supports the close relationship between retained primitive reflexes and cognitive and motor function in general and in ASD in particular provided to indicate that the inhibition of RPRs can effect positive change in ASD.
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Affiliation(s)
- Robert Melillo
- Movement and Cognition Laboratory, Department of Physical Therapy, University of Haifa, Haifa, Israel
| | - Gerry Leisman
- Movement and Cognition Laboratory, Department of Physical Therapy, University of Haifa, Haifa, Israel
- Department of Neurology, University of the Medical Sciences of Havana, Havana, Cuba
| | - Calixto Machado
- Department of Clinical Neurophysiology, Institute for Neurology and Neurosurgery, Havana, Cuba
| | - Yanin Machado-Ferrer
- Department of Clinical Neurophysiology, Institute for Neurology and Neurosurgery, Havana, Cuba
| | | | - Shanine Kamgang
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Ty Melillo
- Northeast College of the Health Sciences, Seneca Falls, New York, NY, United States
| | - Eli Carmeli
- Movement and Cognition Laboratory, Department of Physical Therapy, University of Haifa, Haifa, Israel
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12
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Konstantinides N, Holguera I, Rossi AM, Escobar A, Dudragne L, Chen YC, Tran TN, Martínez Jaimes AM, Özel MN, Simon F, Shao Z, Tsankova NM, Fullard JF, Walldorf U, Roussos P, Desplan C. A complete temporal transcription factor series in the fly visual system. Nature 2022; 604:316-322. [PMID: 35388222 DOI: 10.1038/s41586-022-04564-w] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 02/18/2022] [Indexed: 01/17/2023]
Abstract
The brain consists of thousands of neuronal types that are generated by stem cells producing different neuronal types as they age. In Drosophila, this temporal patterning is driven by the successive expression of temporal transcription factors (tTFs)1-6. Here we used single-cell mRNA sequencing to identify the complete series of tTFs that specify most Drosophila optic lobe neurons. We verify that tTFs regulate the progression of the series by activating the next tTF(s) and repressing the previous one(s), and also identify more complex mechanisms of regulation. Moreover, we establish the temporal window of origin and birth order of each neuronal type in the medulla and provide evidence that these tTFs are sufficient to explain the generation of all of the neuronal diversity in this brain region. Finally, we describe the first steps of neuronal differentiation and show that these steps are conserved in humans. We find that terminal differentiation genes, such as neurotransmitter-related genes, are present as transcripts, but not as proteins, in immature larval neurons. This comprehensive analysis of a temporal series of tTFs in the optic lobe offers mechanistic insights into how tTF series are regulated, and how they can lead to the generation of a complete set of neurons.
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Affiliation(s)
- Nikolaos Konstantinides
- Department of Biology, New York University, New York, NY, USA. .,Université de Paris, CNRS, Institut Jacques Monod, Paris, France.
| | - Isabel Holguera
- Department of Biology, New York University, New York, NY, USA
| | - Anthony M Rossi
- Department of Biology, New York University, New York, NY, USA.,Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | | | | | - Yen-Chung Chen
- Department of Biology, New York University, New York, NY, USA
| | - Thinh N Tran
- Department of Biology, New York University, New York, NY, USA.,Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | | | | | - Félix Simon
- Department of Biology, New York University, New York, NY, USA
| | - Zhiping Shao
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, Institute for Genomics and Multiscale Biology, New York, NY, USA
| | - Nadejda M Tsankova
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - John F Fullard
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, Institute for Genomics and Multiscale Biology, New York, NY, USA.,Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Uwe Walldorf
- Developmental Biology, Saarland University, Homburg, Germany
| | - Panos Roussos
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, Institute for Genomics and Multiscale Biology, New York, NY, USA.,Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Mental Illness Research, Education and Clinical Center (VISN 2 South), James J. Peters VA Medical Center, New York, NY, USA
| | - Claude Desplan
- Department of Biology, New York University, New York, NY, USA. .,Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.
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13
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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.
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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
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14
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Zibetti C. Deciphering the Retinal Epigenome during Development, Disease and Reprogramming: Advancements, Challenges and Perspectives. Cells 2022; 11:cells11050806. [PMID: 35269428 PMCID: PMC8908986 DOI: 10.3390/cells11050806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/15/2022] [Accepted: 02/18/2022] [Indexed: 02/01/2023] Open
Abstract
Retinal neurogenesis is driven by concerted actions of transcription factors, some of which are expressed in a continuum and across several cell subtypes throughout development. While seemingly redundant, many factors diversify their regulatory outcome on gene expression, by coordinating variations in chromatin landscapes to drive divergent retinal specification programs. Recent studies have furthered the understanding of the epigenetic contribution to the progression of age-related macular degeneration, a leading cause of blindness in the elderly. The knowledge of the epigenomic mechanisms that control the acquisition and stabilization of retinal cell fates and are evoked upon damage, holds the potential for the treatment of retinal degeneration. Herein, this review presents the state-of-the-art approaches to investigate the retinal epigenome during development, disease, and reprogramming. A pipeline is then reviewed to functionally interrogate the epigenetic and transcriptional networks underlying cell fate specification, relying on a truly unbiased screening of open chromatin states. The related work proposes an inferential model to identify gene regulatory networks, features the first footprinting analysis and the first tentative, systematic query of candidate pioneer factors in the retina ever conducted in any model organism, leading to the identification of previously uncharacterized master regulators of retinal cell identity, such as the nuclear factor I, NFI. This pipeline is virtually applicable to the study of genetic programs and candidate pioneer factors in any developmental context. Finally, challenges and limitations intrinsic to the current next-generation sequencing techniques are discussed, as well as recent advances in super-resolution imaging, enabling spatio-temporal resolution of the genome.
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Affiliation(s)
- Cristina Zibetti
- Department of Ophthalmology, Institute of Clinical Medicine, University of Oslo, Kirkeveien 166, Building 36, 0455 Oslo, Norway
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15
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Hafer TL, Patra S, Tagami D, Kohwi M. Enhancer of trithorax/polycomb, Corto, regulates timing of hunchback gene relocation and competence in Drosophila neuroblasts. Neural Dev 2022; 17:3. [PMID: 35177098 PMCID: PMC8855600 DOI: 10.1186/s13064-022-00159-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 01/27/2022] [Indexed: 12/27/2022] Open
Abstract
Background Neural progenitors produce diverse cells in a stereotyped birth order, but can specify each cell type for only a limited duration. In the Drosophila embryo, neuroblasts (neural progenitors) specify multiple, distinct neurons by sequentially expressing a series of temporal identity transcription factors with each division. Hunchback (Hb), the first of the series, specifies early-born neuronal identity. Neuroblast competence to generate early-born neurons is terminated when the hb gene relocates to the neuroblast nuclear lamina, rendering it refractory to activation in descendent neurons. Mechanisms and trans-acting factors underlying this process are poorly understood. Here we identify Corto, an enhancer of Trithorax/Polycomb (ETP) protein, as a new regulator of neuroblast competence. Methods We used the GAL4/UAS system to drive persistent misexpression of Hb in neuroblast 7–1 (NB7-1), a model lineage for which the early competence window has been well characterized, to examine the role of Corto in neuroblast competence. We used immuno-DNA Fluorescence in situ hybridization (DNA FISH) in whole embryos to track the position of the hb gene locus specifically in neuroblasts across developmental time, comparing corto mutants to control embryos. Finally, we used immunostaining in whole embryos to examine Corto’s role in repression of Hb and a known target gene, Abdominal B (Abd-B). Results We found that in corto mutants, the hb gene relocation to the neuroblast nuclear lamina is delayed and the early competence window is extended. The delay in gene relocation occurs after hb transcription is already terminated in the neuroblast and is not due to prolonged transcriptional activity. Further, we find that Corto genetically interacts with Posterior Sex Combs (Psc), a core subunit of polycomb group complex 1 (PRC1), to terminate early competence. Loss of Corto does not result in derepression of Hb or its Hox target, Abd-B, specifically in neuroblasts. Conclusions These results show that in neuroblasts, Corto genetically interacts with PRC1 to regulate timing of nuclear architecture reorganization and support the model that distinct mechanisms of silencing are implemented in a step-wise fashion during development to regulate cell fate gene expression in neuronal progeny. Supplementary Information The online version contains supplementary material available at 10.1186/s13064-022-00159-3.
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Affiliation(s)
- Terry L Hafer
- Department of Neuroscience, Mortimer B. Zuckerman Institute Mind Brain Behavior, Columbia University, New York, NY, 10027, USA.,Present Address: Molecular and Cellular Biology Program, University of Washington, Seattle, WA, 98195, USA
| | - Sofiya Patra
- Department of Neuroscience, Mortimer B. Zuckerman Institute Mind Brain Behavior, Columbia University, New York, NY, 10027, USA
| | - Daiki Tagami
- Department of Neuroscience, Mortimer B. Zuckerman Institute Mind Brain Behavior, Columbia University, New York, NY, 10027, USA
| | - Minoree Kohwi
- Department of Neuroscience, Mortimer B. Zuckerman Institute Mind Brain Behavior, Columbia University, New York, NY, 10027, USA. .,Kavli Institute for Brain Science, Columbia University, New York, NY, 10027, USA.
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16
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Buscaglia G, Northington KR, Aiken J, Hoff KJ, Bates EA. Bridging the Gap: The Importance of TUBA1A α-Tubulin in Forming Midline Commissures. Front Cell Dev Biol 2022; 9:789438. [PMID: 35127710 PMCID: PMC8807549 DOI: 10.3389/fcell.2021.789438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/20/2021] [Indexed: 11/13/2022] Open
Abstract
Developing neurons undergo dramatic morphological changes to appropriately migrate and extend axons to make synaptic connections. The microtubule cytoskeleton, made of α/β-tubulin dimers, drives neurite outgrowth, promotes neuronal growth cone responses, and facilitates intracellular transport of critical cargoes during neurodevelopment. TUBA1A constitutes the majority of α-tubulin in the developing brain and mutations to TUBA1A in humans cause severe brain malformations accompanied by varying neurological defects, collectively termed tubulinopathies. Studies of TUBA1A function in mammalian cells have been limited by the presence of multiple genes encoding highly similar tubulin proteins, which leads to α-tubulin antibody promiscuity and makes genetic manipulation challenging. Here, we test mutant tubulin levels and assembly activity and analyze the impact of TUBA1A reduction on growth cone composition, neurite extension, and commissural axon architecture during brain development. We present a novel tagging method for studying and manipulating TUBA1A in cells without impairing tubulin function. Using this tool, we show that a TUBA1A loss-of-function mutation TUBA1A N102D (TUBA1A ND ), reduces TUBA1A protein levels and prevents incorporation of TUBA1A into microtubule polymers. Reduced Tuba1a α-tubulin in heterozygous Tuba1a ND/+ mice leads to grossly normal brain formation except a significant impact on axon extension and impaired formation of forebrain commissures. Neurons with reduced Tuba1a as a result of the Tuba1a ND mutation exhibit slower neuron outgrowth compared to controls. Neurons deficient in Tuba1a failed to localize microtubule associated protein-1b (Map1b) to the developing growth cone, likely impacting stabilization of microtubules. Overall, we show that reduced Tuba1a is sufficient to support neuronal migration and cortex development but not commissure formation, and provide mechanistic insight as to how TUBA1A tunes microtubule function to support neurodevelopment.
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Affiliation(s)
- Georgia Buscaglia
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Kyle R. Northington
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Jayne Aiken
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Katelyn J. Hoff
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Emily A. Bates
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
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17
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Sousa E, Flames N. Transcriptional regulation of neuronal identity. Eur J Neurosci 2021; 55:645-660. [PMID: 34862697 PMCID: PMC9306894 DOI: 10.1111/ejn.15551] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 11/29/2022]
Abstract
Neuronal diversity is an intrinsic feature of the nervous system. Transcription factors (TFs) are key regulators in the establishment of different neuronal identities; how are the actions of different TFs coordinated to orchestrate this diversity? Are there common features shared among the different neuron types of an organism or even among different animal groups? In this review, we provide a brief overview on common traits emerging on the transcriptional regulation of neuron type diversification with a special focus on the comparison between mouse and Caenorhabditis elegans model systems. In the first part, we describe general concepts on neuronal identity and transcriptional regulation of gene expression. In the second part of the review, TFs are classified in different categories according to their key roles at specific steps along the protracted process of neuronal specification and differentiation. The same TF categories can be identified both in mammals and nematodes. Importantly, TFs are very pleiotropic: Depending on the neuron type or the time in development, the same TF can fulfil functions belonging to different categories. Finally, we describe the key role of transcriptional repression at all steps controlling neuronal diversity and propose that acquisition of neuronal identities could be considered a metastable process.
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Affiliation(s)
- Erick Sousa
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
| | - Nuria Flames
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
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18
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Garcia-Perez NC, Bucher G, Buescher M. Shaking hands is a homeodomain transcription factor that controls axon outgrowth of central complex neurons in the insect model Tribolium. Development 2021; 148:272435. [PMID: 34415334 PMCID: PMC8543150 DOI: 10.1242/dev.199368] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 08/09/2021] [Indexed: 01/22/2023]
Abstract
Gene regulatory mechanisms that specify subtype identity of central complex (CX) neurons are the subject of intense investigation. The CX is a compartment within the brain common to all insect species and functions as a ‘command center’ that directs motor actions. It is made up of several thousand neurons, with more than 60 morphologically distinct identities. Accordingly, transcriptional programs must effect the specification of at least as many neuronal subtypes. We demonstrate a role for the transcription factor Shaking hands (Skh) in the specification of embryonic CX neurons in Tribolium. The developmental dynamics of skh expression are characteristic of terminal selectors of subtype identity. In the embryonic brain, skh expression is restricted to a subset of neurons, many of which survive to adulthood and contribute to the mature CX. skh expression is maintained throughout the lifetime in at least some CX neurons. skh knockdown results in axon outgrowth defects, thus preventing the formation of an embryonic CX primordium. The previously unstudied Drosophila skh shows a similar embryonic expression pattern, suggesting that subtype specification of CX neurons may be conserved. Summary: A detailed examination of the developmental expression of the homeodomain transcription factor Shaking hands in Tribolium reveals a role in the formation of the central complex primordium.
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Affiliation(s)
- Natalia Carolina Garcia-Perez
- Johann Friedrich Blumenbach Institute of Zoology, GZMB, Department of Evolutionary Developmental Genetics, University of Goettingen, Justus-von-Liebig Weg 11, 37077 Goettingen, Germany
| | - Gregor Bucher
- Johann Friedrich Blumenbach Institute of Zoology, GZMB, Department of Evolutionary Developmental Genetics, University of Goettingen, Justus-von-Liebig Weg 11, 37077 Goettingen, Germany
| | - Marita Buescher
- Johann Friedrich Blumenbach Institute of Zoology, GZMB, Department of Evolutionary Developmental Genetics, University of Goettingen, Justus-von-Liebig Weg 11, 37077 Goettingen, Germany
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19
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Lucas T, Hafer TL, Zhang HG, Molotkova N, Kohwi M. Discrete cis-acting element regulates developmentally timed gene-lamina relocation and neural progenitor competence in vivo. Dev Cell 2021; 56:2649-2663.e6. [PMID: 34529940 PMCID: PMC8629127 DOI: 10.1016/j.devcel.2021.08.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/24/2021] [Accepted: 08/20/2021] [Indexed: 01/21/2023]
Abstract
The nuclear lamina is typically associated with transcriptional silencing, and peripheral relocation of genes highly correlates with repression. However, the DNA sequences and proteins regulating gene-lamina interactions are largely unknown. Exploiting the developmentally timed hunchback gene movement to the lamina in Drosophila neuroblasts, we identified a 250 bp intronic element (IE) both necessary and sufficient for relocation. The IE can target a reporter transgene to the lamina and silence it. Endogenously, however, hunchback is already repressed prior to relocation. Instead, IE-mediated relocation confers a heritably silenced gene state refractory to activation in descendent neurons, which terminates neuroblast competence to specify early-born identity. Surprisingly, we found that the Polycomb group chromatin factors bind the IE and are required for lamina relocation, revealing a nuclear architectural role distinct from their well-known function in transcriptional repression. Together, our results uncover in vivo mechanisms underlying neuroblast competence and lamina association in heritable gene silencing. In Drosophila neuroblasts, relocation of the hunchback gene locus to the nuclear lamina confers heritable silencing in daughter neurons. Lucas et al. identify a genomic element necessary and sufficient for hunchback gene movement in vivo. Polycomb proteins target this element for lamina relocation, thereby regulating competence, but not hunchback expression.
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Affiliation(s)
- Tanguy Lucas
- Department of Neuroscience, Mortimer B. Zuckerman Institute Mind Brain Behavior, Columbia University, New York, NY 10027, USA
| | - Terry L Hafer
- Department of Neuroscience, Mortimer B. Zuckerman Institute Mind Brain Behavior, Columbia University, New York, NY 10027, USA
| | - Harrison G Zhang
- Department of Neuroscience, Mortimer B. Zuckerman Institute Mind Brain Behavior, Columbia University, New York, NY 10027, USA
| | - Natalia Molotkova
- Department of Neuroscience, Mortimer B. Zuckerman Institute Mind Brain Behavior, Columbia University, New York, NY 10027, USA
| | - Minoree Kohwi
- Department of Neuroscience, Mortimer B. Zuckerman Institute Mind Brain Behavior, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.
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20
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Libé-Philippot B, Vanderhaeghen P. Cellular and Molecular Mechanisms Linking Human Cortical Development and Evolution. Annu Rev Genet 2021; 55:555-581. [PMID: 34535062 DOI: 10.1146/annurev-genet-071719-020705] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The cerebral cortex is at the core of brain functions that are thought to be particularly developed in the human species. Human cortex specificities stem from divergent features of corticogenesis, leading to increased cortical size and complexity. Underlying cellular mechanisms include prolonged patterns of neuronal generation and maturation, as well as the amplification of specific types of stem/progenitor cells. While the gene regulatory networks of corticogenesis appear to be largely conserved among all mammals including humans, they have evolved in primates, particularly in the human species, through the emergence of rapidly divergent transcriptional regulatory elements, as well as recently duplicated novel genes. These human-specific molecular features together control key cellular milestones of human corticogenesis and are often affected in neurodevelopmental disorders, thus linking human neural development, evolution, and diseases. Expected final online publication date for the Annual Review of Genetics, Volume 55 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Baptiste Libé-Philippot
- VIB-KU Leuven Center for Brain & Disease Research, KU Leuven Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium; .,Institut de Recherches Interdisciplinaires en Biologie Humaine et Moléculaire (IRIBHM) and ULB Neuroscience Institute (UNI), Université Libre de Bruxelles (ULB), 1070 Brussels, Belgium
| | - Pierre Vanderhaeghen
- VIB-KU Leuven Center for Brain & Disease Research, KU Leuven Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium; .,Institut de Recherches Interdisciplinaires en Biologie Humaine et Moléculaire (IRIBHM) and ULB Neuroscience Institute (UNI), Université Libre de Bruxelles (ULB), 1070 Brussels, Belgium
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21
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Tidswell ORA, Benton MA, Akam M. The neuroblast timer gene nubbin exhibits functional redundancy with gap genes to regulate segment identity in Tribolium. Development 2021; 148:271199. [PMID: 34351412 PMCID: PMC8406537 DOI: 10.1242/dev.199719] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/23/2021] [Indexed: 12/05/2022]
Abstract
The neuroblast timer genes hunchback, Krüppel, nubbin and castor are expressed in temporal sequence in neural stem cells, and in corresponding spatial sequence along the Drosophila blastoderm. As canonical gap genes, hunchback and Krüppel play a crucial role in insect segmentation, but the roles of nubbin and castor in this process remain ambiguous. We have investigated the expression and functions of nubbin and castor during segmentation in the beetle Tribolium. We show that Tc-hunchback, Tc-Krüppel, Tc-nubbin and Tc-castor are expressed sequentially in the segment addition zone, and that Tc-nubbin regulates segment identity redundantly with two previously described gap/gap-like genes, Tc-giant and Tc-knirps. Simultaneous knockdown of Tc-nubbin, Tc-giant and Tc-knirps results in the formation of ectopic legs on abdominal segments. This homeotic transformation is caused by loss of abdominal Hox gene expression, likely due to expanded Tc-Krüppel expression. Our findings support the theory that the neuroblast timer series was co-opted for use in insect segment patterning, and contribute to our growing understanding of the evolution and function of the gap gene network outside of Drosophila. Summary:nubbin and the gap genes knirps and giant redundantly repress Krüppel expression during segmentation. Simultaneous knockdown of all three genes causes ectopic Krüppel expression and loss of abdominal segment identity.
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Affiliation(s)
| | - Matthew A Benton
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Michael Akam
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
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22
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Nguyen P, Pease NA, Kueh HY. Scalable control of developmental timetables by epigenetic switching networks. J R Soc Interface 2021; 18:20210109. [PMID: 34283940 DOI: 10.1098/rsif.2021.0109] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
During development, progenitor cells follow timetables for differentiation that span many cell generations. These developmental timetables are robustly encoded by the embryo, yet scalably adjustable by evolution, facilitating variation in organism size and form. Epigenetic switches, involving rate-limiting activation steps at regulatory gene loci, control gene activation timing in diverse contexts, and could profoundly impact the dynamics of gene regulatory networks controlling developmental lineage specification. Here, we develop a mathematical framework to model regulatory networks with genes controlled by epigenetic switches. Using this framework, we show that such epigenetic switching networks uphold developmental timetables that robustly span many cell generations, and enable the generation of differentiated cells in precisely defined numbers and fractions. Changes to epigenetic switching networks can readily alter the timing of developmental events within a timetable, or alter the overall speed at which timetables unfold, enabling scalable control over differentiated population sizes. With their robust, yet flexibly adjustable nature, epigenetic switching networks could represent central targets on which evolution acts to manufacture diversity in organism size and form.
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Affiliation(s)
- Phuc Nguyen
- Molecular Engineering and Sciences Program, University of Washington, Seattle, WA, USA
| | - Nicholas A Pease
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Hao Yuan Kueh
- Department of Bioengineering, University of Washington, Seattle, WA, USA.,Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
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23
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Mark B, Lai SL, Zarin AA, Manning L, Pollington HQ, Litwin-Kumar A, Cardona A, Truman JW, Doe CQ. A developmental framework linking neurogenesis and circuit formation in the Drosophila CNS. eLife 2021; 10:67510. [PMID: 33973523 PMCID: PMC8139831 DOI: 10.7554/elife.67510] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/10/2021] [Indexed: 01/02/2023] Open
Abstract
The mechanisms specifying neuronal diversity are well characterized, yet it remains unclear how or if these mechanisms regulate neural circuit assembly. To address this, we mapped the developmental origin of 160 interneurons from seven bilateral neural progenitors (neuroblasts) and identify them in a synapse-scale TEM reconstruction of the Drosophila larval central nervous system. We find that lineages concurrently build the sensory and motor neuropils by generating sensory and motor hemilineages in a Notch-dependent manner. Neurons in a hemilineage share common synaptic targeting within the neuropil, which is further refined based on neuronal temporal identity. Connectome analysis shows that hemilineage-temporal cohorts share common connectivity. Finally, we show that proximity alone cannot explain the observed connectivity structure, suggesting hemilineage/temporal identity confers an added layer of specificity. Thus, we demonstrate that the mechanisms specifying neuronal diversity also govern circuit formation and function, and that these principles are broadly applicable throughout the nervous system.
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Affiliation(s)
- Brandon Mark
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Sen-Lin Lai
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Aref Arzan Zarin
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Laurina Manning
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Heather Q Pollington
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Ashok Litwin-Kumar
- Mortimer B Zuckerman Mind Brain Behavior Institute, Department of Neuroscience, Columbia University, New York, United States
| | - Albert Cardona
- Janelia Research Campus, Howard Hughes Medical Institute, MRC Laboratory of Molecular Biology, Department of Physiology, Development & Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - James W Truman
- Janelia Research Campus, Howard Hughes Medical Institute, Friday Harbor Laboratories, University of Washington, Friday Harbor, United States
| | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
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24
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Mouilleau V, Vaslin C, Robert R, Gribaudo S, Nicolas N, Jarrige M, Terray A, Lesueur L, Mathis MW, Croft G, Daynac M, Rouiller-Fabre V, Wichterle H, Ribes V, Martinat C, Nedelec S. Dynamic extrinsic pacing of the HOX clock in human axial progenitors controls motor neuron subtype specification. Development 2021; 148:148/6/dev194514. [PMID: 33782043 DOI: 10.1242/dev.194514] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 02/16/2021] [Indexed: 12/17/2022]
Abstract
Rostro-caudal patterning of vertebrates depends on the temporally progressive activation of HOX genes within axial stem cells that fuel axial embryo elongation. Whether the pace of sequential activation of HOX genes, the 'HOX clock', is controlled by intrinsic chromatin-based timing mechanisms or by temporal changes in extrinsic cues remains unclear. Here, we studied HOX clock pacing in human pluripotent stem cell-derived axial progenitors differentiating into diverse spinal cord motor neuron subtypes. We show that the progressive activation of caudal HOX genes is controlled by a dynamic increase in FGF signaling. Blocking the FGF pathway stalled induction of HOX genes, while a precocious increase of FGF, alone or with GDF11 ligand, accelerated the HOX clock. Cells differentiated under accelerated HOX induction generated appropriate posterior motor neuron subtypes found along the human embryonic spinal cord. The pacing of the HOX clock is thus dynamically regulated by exposure to secreted cues. Its manipulation by extrinsic factors provides synchronized access to multiple human neuronal subtypes of distinct rostro-caudal identities for basic and translational applications.This article has an associated 'The people behind the papers' interview.
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Affiliation(s)
- Vincent Mouilleau
- Institut du Fer à Moulin, 75005 Paris, France.,Inserm, UMR-S 1270, 75005 Paris, France.,Sorbonne Université, Science and Engineering Faculty, 75005 Paris, France.,I-STEM, UMR 861, Inserm, UEPS, 91100 Corbeil-Essonnes, France
| | - Célia Vaslin
- Institut du Fer à Moulin, 75005 Paris, France.,Inserm, UMR-S 1270, 75005 Paris, France.,Sorbonne Université, Science and Engineering Faculty, 75005 Paris, France
| | - Rémi Robert
- Institut du Fer à Moulin, 75005 Paris, France.,Inserm, UMR-S 1270, 75005 Paris, France.,Sorbonne Université, Science and Engineering Faculty, 75005 Paris, France
| | - Simona Gribaudo
- Institut du Fer à Moulin, 75005 Paris, France.,Inserm, UMR-S 1270, 75005 Paris, France.,Sorbonne Université, Science and Engineering Faculty, 75005 Paris, France
| | - Nour Nicolas
- Laboratory of Development of the Gonads, Unit of Genetic Stability, Stem Cells and Radiation, UMR 967, INSERM, CEA/DSV/iRCM/SCSR, Université Paris Diderot, Sorbonne Paris Cité, Université Paris-Sud, Université Paris-Saclay, Fontenay aux Roses F-92265, France
| | - Margot Jarrige
- I-STEM, UMR 861, Inserm, UEPS, 91100 Corbeil-Essonnes, France
| | - Angélique Terray
- Institut du Fer à Moulin, 75005 Paris, France.,Inserm, UMR-S 1270, 75005 Paris, France.,Sorbonne Université, Science and Engineering Faculty, 75005 Paris, France
| | - Léa Lesueur
- I-STEM, UMR 861, Inserm, UEPS, 91100 Corbeil-Essonnes, France
| | - Mackenzie W Mathis
- Departments of Pathology and Cell Biology, Neuroscience, and Neurology, Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia University Medical Center, New York, NY 10032, USA
| | - Gist Croft
- Departments of Pathology and Cell Biology, Neuroscience, and Neurology, Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia University Medical Center, New York, NY 10032, USA
| | - Mathieu Daynac
- Institut du Fer à Moulin, 75005 Paris, France.,Inserm, UMR-S 1270, 75005 Paris, France.,Sorbonne Université, Science and Engineering Faculty, 75005 Paris, France
| | - Virginie Rouiller-Fabre
- Laboratory of Development of the Gonads, Unit of Genetic Stability, Stem Cells and Radiation, UMR 967, INSERM, CEA/DSV/iRCM/SCSR, Université Paris Diderot, Sorbonne Paris Cité, Université Paris-Sud, Université Paris-Saclay, Fontenay aux Roses F-92265, France
| | - Hynek Wichterle
- Departments of Pathology and Cell Biology, Neuroscience, and Neurology, Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia University Medical Center, New York, NY 10032, USA
| | - Vanessa Ribes
- Université de Paris, CNRS, Institut Jacques Monod, 15 rue Hélène Brion, 75013 Paris, France
| | - Cécile Martinat
- I-STEM, UMR 861, Inserm, UEPS, 91100 Corbeil-Essonnes, France
| | - Stéphane Nedelec
- Institut du Fer à Moulin, 75005 Paris, France .,Inserm, UMR-S 1270, 75005 Paris, France.,Sorbonne Université, Science and Engineering Faculty, 75005 Paris, France
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25
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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.
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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;
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26
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Sood C, Doyle SE, Siegrist SE. Steroid hormones, dietary nutrients, and temporal progression of neurogenesis. CURRENT OPINION IN INSECT SCIENCE 2021; 43:70-77. [PMID: 33127508 PMCID: PMC8058227 DOI: 10.1016/j.cois.2020.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 10/10/2020] [Accepted: 10/16/2020] [Indexed: 05/13/2023]
Abstract
Temporal patterning of neural progenitors, in which different factors are sequentially expressed, is an evolutionarily conserved strategy for generating neuronal diversity during development. In the Drosophila embryo, mechanisms that mediate temporal patterning of neural stem cells (neuroblasts) are largely cell-intrinsic. However, after embryogenesis, neuroblast temporal patterning relies on extrinsic cues as well, as freshly hatched larvae seek out nutrients and other key resources in varying natural environments. We recap current understanding of neuroblast-intrinsic temporal programs and discuss how neuroblast extrinsic cues integrate and coordinate with neuroblast intrinsic programs to control numbers and types of neurons produced. One key emerging extrinsic factor that impacts temporal patterning of neuroblasts and their daughters as well as termination of neurogenesis is the steroid hormone, ecdysone, a known regulator of large-scale developmental transitions in insects and arthropods. Lastly, we consider evolutionary conservation and discuss recent work on thyroid hormone signaling in early vertebrate brain development.
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Affiliation(s)
- Chhavi Sood
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Susan E Doyle
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Sarah E Siegrist
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA.
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27
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Bonnefont J, Vanderhaeghen P. Neuronal fate acquisition and specification: time for a change. Curr Opin Neurobiol 2021; 66:195-204. [PMID: 33412482 PMCID: PMC8064025 DOI: 10.1016/j.conb.2020.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/03/2020] [Accepted: 12/08/2020] [Indexed: 12/15/2022]
Abstract
During embryonic development, neural stem/progenitor cells generate hundreds of different cell types through the combination of intrinsic and extrinsic cues. Recent data obtained in mouse and human cortical neurogenesis provide novel views about this interplay and how it evolves with time, whether during irreversible cell fate transitions that neural stem cells undergo to become neurons, or through gradual temporal changes of competence that lead to increased neuronal diversity from a common stem cell pool. In each case the temporal changes result from a dynamic balance between intracellular states and extracellular signalling factors. The underlying mechanisms are mostly conserved across species, but some display unique features in human corticogenesis, thereby linking temporal features of neurogenesis and human brain evolution.
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Affiliation(s)
- Jérôme Bonnefont
- Université Libre de Bruxelles (U.L.B.), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium; VIB-KULeuven Center for Brain & Disease Research, KULeuven Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium.
| | - Pierre Vanderhaeghen
- Université Libre de Bruxelles (U.L.B.), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium; VIB-KULeuven Center for Brain & Disease Research, KULeuven Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium.
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28
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Hou Y, Zhang Q, Liu H, Wu J, Shi Y, Qi Y, Shao M, Yang Z, Lu J, Wu Z, Gong L, He M. Topographical organization of mammillary neurogenesis and efferent projections in the mouse brain. Cell Rep 2021; 34:108712. [PMID: 33567285 DOI: 10.1016/j.celrep.2021.108712] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 12/01/2020] [Accepted: 01/12/2021] [Indexed: 01/23/2023] Open
Abstract
The mammillary body is a hypothalamic nucleus that has important functions in memory and spatial navigation, but its developmental principles remain not well understood. Here, we identify progenitor-specific Fezf2 expression in the developing mammillary body and develop an intersectional fate-mapping approach to demonstrate that Fezf2+ mammillary progenitors generate mammillary neurons in a rostral-dorsal-lateral to caudal-ventral-medial fashion. Axonal tracing from different temporal cohorts of labeled mammillary neurons reveal their topographical organization. Unsupervised hierarchical clustering based on intrinsic properties further identify two distinct neuronal clusters independent of birthdates in the medial nuclei. In addition, we generate Fezf2 knockout mice and observe the smaller mammillary body with largely normal anatomy and mildly affected cellular electrophysiology, in contrast to more severe deficits in neuronal differentiation and projection in many other brain regions. These results indicate that Fezf2 may function differently in the mammillary body. Our results provide important insights for mammillary development and connectivity.
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Affiliation(s)
- Yongjie Hou
- Institutes of Brain Science, Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Qi Zhang
- Institutes of Brain Science, Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Hongzhi Liu
- Institutes of Brain Science, Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jinyun Wu
- Institutes of Brain Science, Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yun Shi
- Institutes of Brain Science, Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yanqing Qi
- Institutes of Brain Science, Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Mengmeng Shao
- Department of Anatomy and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zhengang Yang
- Institutes of Brain Science, Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jiangteng Lu
- Department of Anatomy and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zhuhao Wu
- Department of Cell, Developmental and Regenerative Biology, Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ling Gong
- Institutes of Brain Science, Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China.
| | - Miao He
- Institutes of Brain Science, Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China.
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29
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Development of motor circuits: From neuronal stem cells and neuronal diversity to motor circuit assembly. Curr Top Dev Biol 2020; 142:409-442. [PMID: 33706923 DOI: 10.1016/bs.ctdb.2020.11.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this review, we discuss motor circuit assembly starting from neuronal stem cells. Until recently, studies of neuronal stem cells focused on how a relatively small pool of stem cells could give rise to a large diversity of different neuronal identities. Historically, neuronal identity has been assayed in embryos by gene expression, gross anatomical features, neurotransmitter expression, and physiological properties. However, these definitions of identity are largely unlinked to mature functional neuronal features relevant to motor circuits. Such mature neuronal features include presynaptic and postsynaptic partnerships, dendrite morphologies, as well as neuronal firing patterns and roles in behavior. This review focuses on recent work that links the specification of neuronal molecular identity in neuronal stem cells to mature, circuit-relevant identity specification. Specifically, these studies begin to address the question: to what extent are the decisions that occur during motor circuit assembly controlled by the same genetic information that generates diverse embryonic neuronal diversity? Much of the research addressing this question has been conducted using the Drosophila larval motor system. Here, we focus largely on Drosophila motor circuits and we point out parallels to other systems. And we highlight outstanding questions in the field. The main concepts addressed in this review are: (1) the description of temporal cohorts-novel units of developmental organization that link neuronal stem cell lineages to motor circuit configuration and (2) the discovery that temporal transcription factors expressed in neuronal stem cells control aspects of circuit assembly by controlling the size of temporal cohorts and influencing synaptic partner choice.
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30
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Dias JM, Alekseenko Z, Jeggari A, Boareto M, Vollmer J, Kozhevnikova M, Wang H, Matise MP, Alexeyenko A, Iber D, Ericson J. A Shh/Gli-driven three-node timer motif controls temporal identity and fate of neural stem cells. SCIENCE ADVANCES 2020; 6:6/38/eaba8196. [PMID: 32938678 PMCID: PMC7494341 DOI: 10.1126/sciadv.aba8196] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 07/28/2020] [Indexed: 05/03/2023]
Abstract
How time is measured by neural stem cells during temporal neurogenesis has remained unresolved. By combining experiments and computational modeling, we define a Shh/Gli-driven three-node timer underlying the sequential generation of motor neurons (MNs) and serotonergic neurons in the brainstem. The timer is founded on temporal decline of Gli-activator and Gli-repressor activities established through down-regulation of Gli transcription. The circuitry conforms an incoherent feed-forward loop, whereby Gli proteins not only promote expression of Phox2b and thereby MN-fate but also account for a delayed activation of a self-promoting transforming growth factor-β (Tgfβ) node triggering a fate switch by repressing Phox2b. Hysteresis and spatial averaging by diffusion of Tgfβ counteract noise and increase temporal accuracy at the population level, providing a functional rationale for the intrinsically programmed activation of extrinsic switch signals in temporal patterning. Our study defines how time is reliably encoded during the sequential specification of neurons.
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Affiliation(s)
- José M Dias
- Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Zhanna Alekseenko
- Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Ashwini Jeggari
- Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Marcelo Boareto
- D-BSSE, ETF Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
- Swiss Institute of Bioinformatics (SIB), Mattenstrasse 26, 4058 Basel, Switzerland
| | - Jannik Vollmer
- D-BSSE, ETF Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
- Swiss Institute of Bioinformatics (SIB), Mattenstrasse 26, 4058 Basel, Switzerland
| | - Mariya Kozhevnikova
- Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Hui Wang
- Department of Neuroscience and Cell Biology, Rutgers-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ, 08854, USA
| | - Michael P Matise
- Department of Neuroscience and Cell Biology, Rutgers-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ, 08854, USA
| | - Andrey Alexeyenko
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
- Science for Life Laboratory, Box 1031, 17121, Solna, Sweden
| | - Dagmar Iber
- D-BSSE, ETF Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
- Swiss Institute of Bioinformatics (SIB), Mattenstrasse 26, 4058 Basel, Switzerland
| | - Johan Ericson
- Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77 Stockholm, Sweden.
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31
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Rossi AM, Desplan C. Extrinsic activin signaling cooperates with an intrinsic temporal program to increase mushroom body neuronal diversity. eLife 2020; 9:58880. [PMID: 32628110 PMCID: PMC7365662 DOI: 10.7554/elife.58880] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 07/03/2020] [Indexed: 12/16/2022] Open
Abstract
Temporal patterning of neural progenitors leads to the sequential production of diverse neurons. To understand how extrinsic cues influence intrinsic temporal programs, we studied Drosophila mushroom body progenitors (neuroblasts) that sequentially produce only three neuronal types: γ, then α’β’, followed by αβ. Opposing gradients of two RNA-binding proteins Imp and Syp comprise the intrinsic temporal program. Extrinsic activin signaling regulates the production of α’β’ neurons but whether it affects the intrinsic temporal program was not known. We show that the activin ligand Myoglianin from glia regulates the temporal factor Imp in mushroom body neuroblasts. Neuroblasts missing the activin receptor Baboon have a delayed intrinsic program as Imp is higher than normal during the α’β’ temporal window, causing the loss of α’β’ neurons, a decrease in αβ neurons, and a likely increase in γ neurons, without affecting the overall number of neurons produced. Our results illustrate that an extrinsic cue modifies an intrinsic temporal program to increase neuronal diversity.
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Affiliation(s)
- Anthony M Rossi
- Department of Biology, New York University, New York, United States
| | - Claude Desplan
- Department of Biology, New York University, New York, United States
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32
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Abstract
Binocular vision depends on retinal ganglion cell (RGC) axon projection either to the same side or to the opposite side of the brain. In this article, we review the molecular mechanisms for decussation of RGC axons, with a focus on axon guidance signaling at the optic chiasm and ipsi- and contralateral axon organization in the optic tract prior to and during targeting. The spatial and temporal features of RGC neurogenesis that give rise to ipsilateral and contralateral identity are described. The albino visual system is highlighted as an apt comparative model for understanding RGC decussation, as albinos have a reduced ipsilateral projection and altered RGC neurogenesis associated with perturbed melanogenesis in the retinal pigment epithelium. Understanding the steps for RGC specification into ipsi- and contralateral subtypes will facilitate differentiation of stem cells into RGCs with proper navigational abilities for effective axon regeneration and correct targeting of higher-order visual centers.
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Affiliation(s)
- Carol Mason
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10027, USA; .,Department of Neuroscience, Columbia University, New York, NY 10027, USA.,Department of Ophthalmology, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA;
| | - Nefeli Slavi
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA;
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33
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Ma TC, Vong KI, Kwan KM. Spatiotemporal Decline of BMP Signaling Activity in Neural Progenitors Mediates Fate Transition and Safeguards Neurogenesis. Cell Rep 2020; 30:3616-3624.e4. [DOI: 10.1016/j.celrep.2020.02.089] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 11/13/2019] [Accepted: 02/25/2020] [Indexed: 01/12/2023] Open
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34
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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.
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35
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Coolen M, Labusch M, Mannioui A, Bally-Cuif L. Mosaic Heterochrony in Neural Progenitors Sustains Accelerated Brain Growth and Neurogenesis in the Juvenile Killifish N. furzeri. Curr Biol 2020; 30:736-745.e4. [PMID: 32004451 PMCID: PMC7040570 DOI: 10.1016/j.cub.2019.12.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/16/2019] [Accepted: 12/13/2019] [Indexed: 12/19/2022]
Abstract
Although developmental mechanisms driving an increase in brain size during vertebrate evolution are actively studied, we know less about evolutionary strategies allowing accelerated brain growth. In zebrafish and other vertebrates studied to date, apical radial glia (RG) constitute the primary neurogenic progenitor population throughout life [1]; thus, RG activity is a determining factor of growth speed. Here, we ask whether enhanced RG activity is the mechanism selected to drive explosive growth, in adaptation to an ephemeral habitat. In post-hatching larvae of the turquoise killifish, which display drastic developmental acceleration, we show that the dorsal telencephalon (pallium) grows three times faster than in zebrafish. Rather than resulting from enhanced RG activity, we demonstrate that pallial growth is the product of a second type of progenitors (that we term NGPs for non-glial progenitors) that actively sustains neurogenesis and germinal zone self-renewal. Intriguingly, NGPs appear to retain, at larval stages, features of early embryonic progenitors. In parallel, RGs enter premature quiescence and express markers of astroglial function. Altogether, we propose that mosaic heterochrony within the neural progenitor population might permit rapid pallial growth by safeguarding both continued neurogenesis and astroglial function. Two types of apical progenitors exist in the pallium of the fast-growing killifish Killifish pallial RGs enter precociously into an adult-like quiescent state NGPs, both self-renewing and neurogenic, resemble early neuroepithelial progenitors Mosaic heterochrony among progenitors sustains rapid killifish pallial growth
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Affiliation(s)
- Marion Coolen
- Zebrafish Neurogenetics Unit, Developmental & Stem Cell Biology Department, Institut Pasteur, UMR3738, CNRS, 25 rue du Dr Roux, 75015 Paris, France.
| | - Miriam Labusch
- Zebrafish Neurogenetics Unit, Developmental & Stem Cell Biology Department, Institut Pasteur, UMR3738, CNRS, 25 rue du Dr Roux, 75015 Paris, France; Sorbonne Université, Collège doctoral, 75005 Paris, France
| | - Abdelkrim Mannioui
- Institut de Biologie Paris-Seine (IBPS), Aquatic Facility, Sorbonne Université, 7 quai Saint Bernard, 75005 Paris, France
| | - Laure Bally-Cuif
- Zebrafish Neurogenetics Unit, Developmental & Stem Cell Biology Department, Institut Pasteur, UMR3738, CNRS, 25 rue du Dr Roux, 75015 Paris, France.
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36
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Samuels TJ, Järvelin AI, Ish-Horowicz D, Davis I. Imp/IGF2BP levels modulate individual neural stem cell growth and division through myc mRNA stability. eLife 2020; 9:e51529. [PMID: 31934860 PMCID: PMC7025822 DOI: 10.7554/elife.51529] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 01/13/2020] [Indexed: 12/24/2022] Open
Abstract
The numerous neurons and glia that form the brain originate from tightly controlled growth and division of neural stem cells, regulated systemically by important known stem cell-extrinsic signals. However, the cell-intrinsic mechanisms that control the distinctive proliferation rates of individual neural stem cells are unknown. Here, we show that the size and division rates of Drosophila neural stem cells (neuroblasts) are controlled by the highly conserved RNA binding protein Imp (IGF2BP), via one of its top binding targets in the brain, myc mRNA. We show that Imp stabilises myc mRNA leading to increased Myc protein levels, larger neuroblasts, and faster division rates. Declining Imp levels throughout development limit myc mRNA stability to restrain neuroblast growth and division, and heterogeneous Imp expression correlates with myc mRNA stability between individual neuroblasts in the brain. We propose that Imp-dependent regulation of myc mRNA stability fine-tunes individual neural stem cell proliferation rates.
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Affiliation(s)
- Tamsin J Samuels
- Department of BiochemistryThe University of OxfordOxfordUnited Kingdom
| | - Aino I Järvelin
- Department of BiochemistryThe University of OxfordOxfordUnited Kingdom
| | - David Ish-Horowicz
- Department of BiochemistryThe University of OxfordOxfordUnited Kingdom
- MRC Laboratory for Molecular Cell BiologyUniversity CollegeLondonUnited Kingdom
| | - Ilan Davis
- Department of BiochemistryThe University of OxfordOxfordUnited Kingdom
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37
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Meng JL, Wang Y, Carrillo RA, Heckscher ES. Temporal transcription factors determine circuit membership by permanently altering motor neuron-to-muscle synaptic partnerships. eLife 2020; 9:56898. [PMID: 32391795 PMCID: PMC7242025 DOI: 10.7554/elife.56898] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 05/09/2020] [Indexed: 01/01/2023] Open
Abstract
How circuit wiring is specified is a key question in developmental neurobiology. Previously, using the Drosophila motor system as a model, we found the classic temporal transcription factor Hunchback acts in NB7-1 neuronal stem cells to control the number of NB7-1 neuronal progeny form functional synapses on dorsal muscles (Meng et al., 2019). However, it is unknown to what extent control of motor neuron-to-muscle synaptic partnerships is a general feature of temporal transcription factors. Here, we perform additional temporal transcription factor manipulations-prolonging expression of Hunchback in NB3-1, as well as precociously expressing Pdm and Castor in NB7-1. We use confocal microscopy, calcium imaging, and electrophysiology to show that in every manipulation there are permanent alterations in neuromuscular synaptic partnerships. Our data show temporal transcription factors, as a group of molecules, are potent determinants of synaptic partner choice and therefore ultimately control circuit membership.
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Affiliation(s)
- Julia L Meng
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States,Program in Cell and Molecular Biology, University of ChicagoChicagoUnited States
| | - Yupu Wang
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States,Committee on Development, Regeneration, and Stem Cell Biology, University of ChicagoChicagoUnited States
| | - Robert A Carrillo
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States,Program in Cell and Molecular Biology, University of ChicagoChicagoUnited States,Committee on Development, Regeneration, and Stem Cell Biology, University of ChicagoChicagoUnited States,Grossman Institute for Neuroscience, University of ChicagoChicagoUnited States
| | - Ellie S Heckscher
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States,Program in Cell and Molecular Biology, University of ChicagoChicagoUnited States,Committee on Development, Regeneration, and Stem Cell Biology, University of ChicagoChicagoUnited States,Grossman Institute for Neuroscience, University of ChicagoChicagoUnited States
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38
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Bonnefont J, Tiberi L, van den Ameele J, Potier D, Gaber ZB, Lin X, Bilheu A, Herpoel A, Velez Bravo FD, Guillemot F, Aerts S, Vanderhaeghen P. Cortical Neurogenesis Requires Bcl6-Mediated Transcriptional Repression of Multiple Self-Renewal-Promoting Extrinsic Pathways. Neuron 2019; 103:1096-1108.e4. [PMID: 31353074 PMCID: PMC6859502 DOI: 10.1016/j.neuron.2019.06.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 05/08/2019] [Accepted: 06/26/2019] [Indexed: 12/14/2022]
Abstract
During neurogenesis, progenitors switch from self-renewal to differentiation through the interplay of intrinsic and extrinsic cues, but how these are integrated remains poorly understood. Here, we combine whole-genome transcriptional and epigenetic analyses with in vivo functional studies to demonstrate that Bcl6, a transcriptional repressor previously reported to promote cortical neurogenesis, acts as a driver of the neurogenic transition through direct silencing of a selective repertoire of genes belonging to multiple extrinsic pathways promoting self-renewal, most strikingly the Wnt pathway. At the molecular level, Bcl6 represses its targets through Sirt1 recruitment followed by histone deacetylation. Our data identify a molecular logic by which a single cell-intrinsic factor represses multiple extrinsic pathways that favor self-renewal, thereby ensuring robustness of neuronal fate transition.
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Affiliation(s)
- Jerome Bonnefont
- Université Libre de Bruxelles (ULB), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium; VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | - Luca Tiberi
- Université Libre de Bruxelles (ULB), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium
| | - Jelle van den Ameele
- Université Libre de Bruxelles (ULB), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium
| | - Delphine Potier
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | | | - Xionghui Lin
- Université Libre de Bruxelles (ULB), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium
| | - Angéline Bilheu
- Université Libre de Bruxelles (ULB), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium
| | - Adèle Herpoel
- Université Libre de Bruxelles (ULB), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium
| | - Fausto D Velez Bravo
- Université Libre de Bruxelles (ULB), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium; VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | | | - Stein Aerts
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | - Pierre Vanderhaeghen
- Université Libre de Bruxelles (ULB), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), and ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium; VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Neurosciences, Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium; Welbio, Université Libre de Bruxelles (ULB), 1070 Brussels, Belgium.
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39
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Lo Giudice Q, Leleu M, La Manno G, Fabre PJ. Single-cell transcriptional logic of cell-fate specification and axon guidance in early-born retinal neurons. Development 2019; 146:dev.178103. [PMID: 31399471 DOI: 10.1242/dev.178103] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/30/2019] [Indexed: 12/12/2022]
Abstract
Retinal ganglion cells (RGCs), cone photoreceptors (cones), horizontal cells and amacrine cells are the first classes of neurons produced in the retina. However, an important question is how this diversity of cell states is transcriptionally produced. Here, we profiled 6067 single retinal cells to provide a comprehensive transcriptomic atlas showing the diversity of the early developing mouse retina. RNA velocities unveiled the dynamics of cell cycle coordination of early retinogenesis and define the transcriptional sequences at work during the hierarchical production of early cell-fate specification. We show that RGC maturation follows six waves of gene expression, with older-generated RGCs transcribing increasing amounts of guidance cues for young peripheral RGC axons that express the matching receptors. Spatial transcriptionally deduced features in subpopulations of RGCs allowed us to define novel molecular markers that are spatially restricted. Finally, the isolation of such a spatially restricted population, ipsilateral RGCs, allowed us to identify their molecular identity at the time they execute axon guidance decisions. Together, these data represent a valuable resource shedding light on transcription factor sequences and guidance cue dynamics during mouse retinal development.
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Affiliation(s)
- Quentin Lo Giudice
- Department of Basic Neurosciences, University of Geneva, 1205 Geneva, Switzerland
| | - Marion Leleu
- Faculty of Life Sciences, Ecole Polytechnique Fédérale, Lausanne, 1015 Lausanne, Switzerland.,Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland
| | - Gioele La Manno
- Faculty of Life Sciences, Ecole Polytechnique Fédérale, Lausanne, 1015 Lausanne, Switzerland.,Laboratory of Neurodevelopmental Systems Biology, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Pierre J Fabre
- Department of Basic Neurosciences, University of Geneva, 1205 Geneva, Switzerland
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40
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Assawachananont J, Kim SY, Kaya KD, Fariss R, Roger JE, Swaroop A. Cone-rod homeobox CRX controls presynaptic active zone formation in photoreceptors of mammalian retina. Hum Mol Genet 2019; 27:3555-3567. [PMID: 30084954 DOI: 10.1093/hmg/ddy272] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 07/19/2018] [Indexed: 12/14/2022] Open
Abstract
In the mammalian retina, rod and cone photoreceptors transmit the visual information to bipolar neurons through highly specialized ribbon synapses. We have limited understanding of regulatory pathways that guide morphogenesis and organization of photoreceptor presynaptic architecture in the developing retina. While neural retina leucine zipper (NRL) transcription factor determines rod cell fate and function, cone-rod homeobox (CRX) controls the expression of both rod- and cone-specific genes and is critical for terminal differentiation of photoreceptors. A comprehensive immunohistochemical evaluation of Crx-/- (null), CrxRip/+ and CrxRip/Rip (models of dominant congenital blindness) mouse retinas revealed abnormal photoreceptor synapses, with atypical ribbon shape, number and length. Integrated analysis of retinal transcriptomes of Crx-mutants with CRX- and NRL-ChIP-Seq data identified a subset of differentially expressed CRX target genes that encode presynaptic proteins associated with the cytomatrix active zone (CAZ) and synaptic vesicles. Immunohistochemistry of Crx-mutant retina validated aberrant expression of REEP6, PSD95, MPP4, UNC119, UNC13, RGS7 and RGS11, with some reduction in Ribeye and no significant change in immunostaining of RIMS1, RIMS2, Bassoon and Pikachurin. Our studies demonstrate that CRX controls the establishment of CAZ and anchoring of ribbons, but not the formation of ribbon itself, in photoreceptor presynaptic terminals.
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Affiliation(s)
- Juthaporn Assawachananont
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Soo-Young Kim
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Koray D Kaya
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Robert Fariss
- Imaging Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jerome E Roger
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.,Centre d'Etude et de Recherches Thérapeutiques en Ophthalmologie, Retina France, Orsay, France.,Paris-Saclay Institute of Neuroscience, CNRS, Univ Paris Sud, Université Paris-Saclay, Orsay, France
| | - Anand Swaroop
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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41
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Seroka AQ, Doe CQ. The Hunchback temporal transcription factor determines motor neuron axon and dendrite targeting in Drosophila. Development 2019; 146:dev175570. [PMID: 30890568 PMCID: PMC6467472 DOI: 10.1242/dev.175570] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/11/2019] [Indexed: 12/14/2022]
Abstract
The generation of neuronal diversity is essential for circuit formation and behavior. Morphological differences in sequentially born neurons could be due to intrinsic molecular identity specified by temporal transcription factors (henceforth called intrinsic temporal identity) or due to changing extrinsic cues. Here, we have used the Drosophila NB7-1 lineage to address this issue. NB7-1 generates the U1-U5 motor neurons sequentially; each has a distinct intrinsic temporal identity due to inheritance of different temporal transcription factors at its time of birth. We show that the U1-U5 neurons project axons sequentially, followed by sequential dendrite extension. We misexpressed the earliest temporal transcription factor, Hunchback, to create 'ectopic' U1 neurons with an early intrinsic temporal identity but later birth-order. These ectopic U1 neurons have axon muscle targeting and dendrite neuropil targeting that are consistent with U1 intrinsic temporal identity, rather than with their time of birth or differentiation. We conclude that intrinsic temporal identity plays a major role in establishing both motor axon muscle targeting and dendritic arbor targeting, which are required for proper motor circuit development.
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Affiliation(s)
- Austin Q Seroka
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Chris Q Doe
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
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42
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Venkatasubramanian L, Mann RS. The development and assembly of the Drosophila adult ventral nerve cord. Curr Opin Neurobiol 2019; 56:135-143. [PMID: 30826502 DOI: 10.1016/j.conb.2019.01.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 01/15/2019] [Indexed: 01/05/2023]
Abstract
In order to generate complex motor outputs, the nervous system integrates multiple sources of sensory information that ultimately controls motor neurons to generate coordinated movements. The neural circuits that integrate higher order commands from the brain and generate motor outputs are located in the nerve cord of the central nervous system. Recently, genetic access to distinct functional subtypes that make up the Drosophila adult ventral nerve cord has significantly begun to advance our understanding of the structural organization and functions of the neural circuits coordinating motor outputs. Moreover, lineage-tracing and genetic intersection tools have been instrumental in deciphering the developmental mechanisms that generate and assemble the functional units of the adult nerve cord. Together, the Drosophila adult ventral nerve cord is emerging as a powerful system to understand the development and function of neural circuits that are responsible for coordinating complex motor outputs.
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Affiliation(s)
- Lalanti Venkatasubramanian
- Department of Biochemistry and Molecular Biophysics, Department of Neuroscience, Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, United States
| | - Richard S Mann
- Department of Biochemistry and Molecular Biophysics, Department of Neuroscience, Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, United States.
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43
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Sullivan LF, Warren TL, Doe CQ. Temporal identity establishes columnar neuron morphology, connectivity, and function in a Drosophila navigation circuit. eLife 2019; 8:43482. [PMID: 30706848 PMCID: PMC6386519 DOI: 10.7554/elife.43482] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/31/2019] [Indexed: 12/28/2022] Open
Abstract
The insect central complex (CX) is a conserved brain region containing 60 + neuronal subtypes, several of which contribute to navigation. It is not known how CX neuronal diversity is generated or how developmental origin of subtypes relates to function. We mapped the developmental origin of four key CX subtypes and found that neurons with similar origin have similar axon/dendrite targeting. Moreover, we found that the temporal transcription factor (TTF) Eyeless/Pax6 regulates the development of two recurrently-connected CX subtypes: Eyeless loss simultaneously produces ectopic P-EN neurons with normal axon/dendrite projections, and reduces the number of E-PG neurons. Furthermore, transient loss of Eyeless during development impairs adult flies’ capacity to perform celestial navigation. We conclude that neurons with similar developmental origin have similar connectivity, that Eyeless maintains equal E-PG and P-EN neuron number, and that Eyeless is required for the development of circuits that control adult navigation. Every task that an animal performs, even a simple one, typically requires numerous signals to pass across complex networks of cells called neurons. These networks develop early in an animal’s life, beginning when progenitor cells called neural stem cells divide over and over to produce new cells. Specific molecular signals then induce these new cells to become different types of neurons. However, in many animals, it is poorly understood what these critical molecular signals are and how they work. Fruit flies, for example, have a network of neurons that control how they navigate when flying. The same type of progenitor cell gives rise to at least four types of neurons in this network; these progenitor cells make an increasing amount of a protein called Eyeless as they age. Sullivan et al. have now specifically disrupted production of the Eyeless protein in the progenitor cells, and found that this altered the relative numbers of navigation neurons. The fruit flies had too many of some types of navigation neurons and too few of others. Fruit flies normally navigate in a variety of directions relative to the sun, which may allow them to disperse and find food. This was not the case in experiments where the production of Eyeless was briefly disrupted when the flies were larvae. In these experiments, the adult flies tended to head towards a bright light (that represented the sun) much more often than normal, which would presumably keep them from dispersing effectively. This was true even if the disruption of Eyeless was not long enough to change the numbers of neuron types, showing the protein is important in determining both how these navigation neurons form networks, and whether they are born at all. A better understanding of the complexities of how healthy networks of neurons develop may give scientists more insight into what goes wrong during human developmental disorders that affect the brain. In theory, it may also someday lead to tools that can help to repair the brain if it is damaged.
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Affiliation(s)
- Luis F Sullivan
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States.,Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Timothy L Warren
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States.,Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Chris Q Doe
- Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
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44
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Wu D, Wu L, An H, Bao H, Guo P, Zhang B, Zheng H, Zhang F, Ge W, Cai Y, Xi Y, Yang X. RanGAP-mediated nucleocytoplasmic transport of Prospero regulates neural stem cell lifespan in Drosophila larval central brain. Aging Cell 2019; 18:e12854. [PMID: 30549175 PMCID: PMC6351831 DOI: 10.1111/acel.12854] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 06/24/2018] [Accepted: 07/30/2018] [Indexed: 11/28/2022] Open
Abstract
By the end of neurogenesis in Drosophila pupal brain neuroblasts (NBs), nuclear Prospero (Pros) triggers cell cycle exit and terminates NB lifespan. Here, we reveal that in larval brain NBs, an intrinsic mechanism facilitates import and export of Pros across the nuclear envelope via a Ran‐mediated nucleocytoplasmic transport system. In rangap mutants, the export of Pros from the nucleus to cytoplasm is impaired and the nucleocytoplasmic transport of Pros becomes one‐way traffic, causing an early accumulation of Pros in the nuclei of the larval central brain NBs. This nuclear Pros retention initiates NB cell cycle exit and leads to a premature decrease of total NB numbers. Our data indicate that RanGAP plays a crucial role in this intrinsic mechanism that controls NB lifespan during neurogenesis. Our study may provide insights into understanding the lifespan of neural stem cells during neurogenesis in other organisms.
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Affiliation(s)
- Di Wu
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Litao Wu
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Huanping An
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Hongcun Bao
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Pengfei Guo
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Bei Zhang
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Huimei Zheng
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
| | - Fan Zhang
- College of Life Sciences Zhejiang University Hangzhou China
| | - Wanzhong Ge
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
| | - Yu Cai
- Temasek Life Sciences Laboratory National University of Singapore Singapore
- Department of Biological Sciences National University of Singapore Singapore
| | - Yongmei Xi
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
| | - Xiaohang Yang
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- Joint Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Zhejiang University Hangzhou China
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45
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A Notch-mediated, temporal asymmetry in BMP pathway activation promotes photoreceptor subtype diversification. PLoS Biol 2019; 17:e2006250. [PMID: 30703098 PMCID: PMC6372210 DOI: 10.1371/journal.pbio.2006250] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 02/12/2019] [Accepted: 01/22/2019] [Indexed: 11/19/2022] Open
Abstract
Neural progenitors produce neurons whose identities can vary as a function of the time that specification occurs. Here, we describe the heterochronic specification of two photoreceptor (PhR) subtypes in the zebrafish pineal gland. We find that accelerating PhR specification by impairing Notch signaling favors the early fate at the expense of the later fate. Using in vivo lineage tracing, we show that most pineal PhRs are born from a fate-restricted progenitor. Furthermore, sister cells derived from the division of PhR-restricted progenitors activate the bone morphogenetic protein (BMP) signaling pathway at different times after division, and this heterochrony requires Notch activity. Finally, we demonstrate that PhR identity is established as a function of when the BMP pathway is activated. We propose a novel model in which division of a progenitor with restricted potential generates sister cells with distinct identities via a temporal asymmetry in the activation of a signaling pathway. A major goal in the field of developmental neurobiology is to identify the mechanisms that underly the diversification of the subtypes of neurons that are needed for the function of the nervous system. When investigating these mechanisms, time is an often-overlooked variable. Here, we show that in the zebrafish pineal gland—a neuroendocrine organ containing mostly photoreceptors (PhRs) and projection neurons—different classes of PhRs appear in a temporal sequence. In this simple system, the decision to adopt a PhR fate is driven by the activation of the bone morphogenetic protein (BMP) signaling pathway. Following the final cell division of a PhR progenitor, the sister cells normally activate the BMP pathway at different times. When Notch signaling activity is abrogated, activation of the BMP pathway occurs earlier and synchronously, which in turn favors the development of early PhR fates at the expense of later fates. We propose a model in which preventing sister cells from activating a signaling pathway in a synchronous fashion after their final division allows diversification of cell fates.
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46
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Averbukh I, Lai SL, Doe CQ, Barkai N. A repressor-decay timer for robust temporal patterning in embryonic Drosophila neuroblast lineages. eLife 2018; 7:38631. [PMID: 30526852 PMCID: PMC6303102 DOI: 10.7554/elife.38631] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 12/10/2018] [Indexed: 11/13/2022] Open
Abstract
Biological timers synchronize patterning processes during embryonic development. In the Drosophila embryo, neural progenitors (neuroblasts; NBs) produce a sequence of unique neurons whose identities depend on the sequential expression of temporal transcription factors (TTFs). The stereotypy and precision of NB lineages indicate reproducible TTF timer progression. We combine theory and experiments to define the timer mechanism. The TTF timer is commonly described as a relay of activators, but its regulatory circuit is also consistent with a repressor-decay timer, where TTF expression begins when its repressor decays. Theory shows that repressor-decay timers are more robust to parameter variations than activator-relay timers. This motivated us to experimentally compare the relative importance of the relay and decay interactions in vivo. Comparing WT and mutant NBs at high temporal resolution, we show that the TTF sequence progresses primarily by repressor-decay. We suggest that need for robust performance shapes the evolutionary-selected designs of biological circuits.
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Affiliation(s)
- Inna Averbukh
- Department of Molecular Genetics, Weizmann institute of science, Rehovot, Israel
| | - Sen-Lin Lai
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Chris Q Doe
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann institute of science, Rehovot, Israel
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47
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Transcriptional control of long-range cortical projections. Curr Opin Neurobiol 2018; 53:57-65. [DOI: 10.1016/j.conb.2018.05.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 05/23/2018] [Indexed: 12/11/2022]
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48
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Kawaguchi A. Temporal patterning of neocortical progenitor cells: How do they know the right time? Neurosci Res 2018; 138:3-11. [PMID: 30227161 DOI: 10.1016/j.neures.2018.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 08/09/2018] [Accepted: 08/09/2018] [Indexed: 10/28/2022]
Abstract
During mammalian neocortical development, neural progenitor cells undergo sequential division to produce different types of progenies. Regulation of when and how many cells with a specific fate are produced from neural progenitor cells, i.e., 'temporal patterning' for cytogenesis, is crucial for the formation of the functional neocortex. Recently advanced techniques for transcriptome profiling at the single-cell level provide a solid basis to investigate the molecular nature underlying temporal patterning, including examining the necessity of cell-cycle progression. Evidence has indicated that cell-intrinsic programs and extrinsic cues coordinately regulate the timing of both the change in the division mode of neural progenitors from proliferative to neurogenic and their laminar fate transition from deep-layer to upper-layer neurons. Epigenetic modulation, transcriptional cascades, and post-transcriptional regulation are reported to function as cell-intrinsic programs, whereas extrinsic cues from the environment or surrounding cells supposedly function in a negative feedback or positive switching manner for temporal patterning. These findings suggest that neural progenitor cells have intrinsic temporal programs that can progress cell-autonomously and cell-cycle independently, while extrinsic cues play a critical role in tuning the temporal programs to let neural progenitor cells know the 'right' time to progress.
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Affiliation(s)
- Ayano Kawaguchi
- Department of Anatomy and Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya, Aichi, 466-8550, Japan.
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49
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Abstract
Understanding the development of the human brain in relation with evolution is an important frontier field in developmental biology. In particular, investigating the mechanisms underlying the greatly increased relative size and complexity of the cerebral cortex, the seat of our enhanced cognitive abilities, remains a fascinating yet largely unsolved question. Though many advances in our understanding have been gained from the study of animal models, as well as human genetics and embryology, large gaps remain in our knowledge of the molecular mechanisms that control human cortical development. Interestingly, many aspects of corticogenesis can be recapitulated in vitro from mouse and human embryonic or induced pluripotent stem cells (PSCs), using a variety of experimental systems from 2D models to organoids to xenotransplantation. This has provided the opportunity to study these processes in an accessible and physiologically relevant setting. In this chapter, we will discuss how conserved and divergent features of primate/human corticogenesis can be modeled and studied mechanistically using PSC-based models of corticogenesis. We will also review what has been learned through these approaches about pathological defects of human corticogenesis, from early neurogenesis to late neuronal maturation and connectivity.
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50
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Viader-Llargués O, Lupperger V, Pola-Morell L, Marr C, López-Schier H. Live cell-lineage tracing and machine learning reveal patterns of organ regeneration. eLife 2018; 7:30823. [PMID: 29595471 PMCID: PMC5903862 DOI: 10.7554/elife.30823] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 03/28/2018] [Indexed: 12/28/2022] Open
Abstract
Despite the intrinsically stochastic nature of damage, sensory organs recapitulate normal architecture during repair to maintain function. Here we present a quantitative approach that combines live cell-lineage tracing and multifactorial classification by machine learning to reveal how cell identity and localization are coordinated during organ regeneration. We use the superficial neuromasts in larval zebrafish, which contain three cell classes organized in radial symmetry and a single planar-polarity axis. Visualization of cell-fate transitions at high temporal resolution shows that neuromasts regenerate isotropically to recover geometric order, proportions and polarity with exceptional accuracy. We identify mediolateral position within the growing tissue as the best predictor of cell-fate acquisition. We propose a self-regulatory mechanism that guides the regenerative process to identical outcome with minimal extrinsic information. The integrated approach that we have developed is simple and broadly applicable, and should help define predictive signatures of cellular behavior during the construction of complex tissues.
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Affiliation(s)
- Oriol Viader-Llargués
- Unit Sensory Biology & Organogenesis, Helmholtz Zentrum München, Neuherberg, Germany.,Laboratory of Sensory Cell Biology, Centre for Genomic Regulation, Barcelona, Spain
| | - Valerio Lupperger
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Laura Pola-Morell
- Unit Sensory Biology & Organogenesis, Helmholtz Zentrum München, Neuherberg, Germany.,Laboratory of Sensory Cell Biology, Centre for Genomic Regulation, Barcelona, Spain
| | - Carsten Marr
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Hernán López-Schier
- Unit Sensory Biology & Organogenesis, Helmholtz Zentrum München, Neuherberg, Germany.,Laboratory of Sensory Cell Biology, Centre for Genomic Regulation, Barcelona, Spain
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