DOCSLIB.ORG

Early Events of Neural Development

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Early Events of Neural Development Early events of neural development Goals: 1) to discuss the origins of cells in the nervous system 2) to discuss how neural stem cells generate diverse cell types in the nervous system The next four lectures will cover: Induction (Jan 22)...emergence of the nervous system Regionalization (Jan 24)...acquisition of positional information of neural cells Discussion of a journal article (Jan 26) Cell division and cell lineage (Jan 29) Neuronal fate specification (Jan 31) Discussion of a journal article (Feb 2) We will deal with glia later in the course! 1 Outline of this lecture Control of daughter cell fates after cell division (RGC vs differentiating cell) -Notch-Delta signaling -proneural basic helix-loop-helix (bHLH) transcription factors Identity of progenitor cells influence the type of neurons that the progenitor cell produces. -regional identity (outcome of regionalization) -temporal identity (RGCs changes as they undergo asymmetric divisions) Neuronal fate can be controlled postmitotically. 2 Published online: March 17, 2014 EMBO reports Neurogenesis during vertebrate development Judith TML Paridaen & Wieland B Huttner Published online: March 17, 2014 EMBO reports Neurogenesis during vertebrate development Judith TML Paridaen & Wieland B Huttner A C Regulation of spindle orientation Symmetric division Planar Oblique Horizontal NPCA 2 NPCs C Regulation of spindle orientation Mammalian neurogenesis Drosophila neuroblast Symmetric division Planar Oblique Horizontal NPC 2 NPCs Mammalian neurogenesis Drosophila neuroblast Apical Centrosome Spindle Basal Par3/Par6/aPKC ASPM LGN/NuMA/G Miranda/Numb ApicalAdherens junctions CentrosomeCdk5rap2 SpindleInsc Basal ASPM LGN/NuMA/G Par3/Par6/aPKC MCPH1 Lis1/Ndel1 CellMiranda/Numb cortex Adherens junctions Cdk5rap2 InscDynein MCPH1 Lis1/Ndel1 Cell cortex Inheritance of fate determinants B D Dynein Asymmetric division Symmetric Asymmetric Asymmetric Inheritance of fate determinants NPCB 1 NPC + 1 Neuron D Mouse Zebrafish Symmetric Asymmetric Asymmetric Asymmetric division Splitting/ Mouse Zebrafish NPC 1 NPC + 1 Neuron Regrowth? Splitting/ Regrowth? Notch Notch Notch Notch Notch Notch RGC RGC RGC IP Neuron RGC Neuron Notch Notch Notch Notch Notch Notch ApicalRGC RGCCentrosomeRGC IPCytoplasmicNeuron RGCBasal Neuron Par3/Par6/aPKC Mother centriole Mindbomb Ccnd2 Apical Centrosome Cytoplasmic Basal Adherens junctions Daughter centriole Numb Trim32 ProneuralPar3/Par6/aPKC transcriptionMother centriole Mindbomb Ccnd2 factors promote Ciliary membrane Delta-like 1 Adherens junctions Daughter centriole Numb Trim32 Staufen2 + mRNAs Ciliary membrane Delta-like 1 Staufen2 + mRNAs Apical E Centrosomeneuronal inheritance differentiationF Notch signaling ApicalPar3/Par6/aPKC E Centrosome inheritance F Notch signaling AdherensPar3/Par6/aPKC junctions The differentiating daughter cell generated after an CentrosomeAdherens junctions ngn2 CentrosomeMother centriole asymmetricngn2 division of a RGC expresses the proneural Daughter centriole Mother centriole transcription factorngn2 Neurogenin 2 (Neurog2 or Ngn2). CiliaryDaughter membrane centriole ngn2 CytoplasmicCiliary membrane CytoplasmicMindbomb Neurogenin 2 belongs to a family of transcription Mindbomb Cell surface Cell ngn2 factors with a basic helix-loop-helix (bHLH) domain. cycle CellDelta surface Cell ngn2 Hes1 cycle ngn2 NotchDelta Hes1ngn2 ngn2 Notch Neurogenin ngn22 promotes neuronal differentiation. Activation InhibitionActivation DelaminationInhibition Delamination Neurogenin 2 promotes transcription of Tbr2, an IPC Daughter Daughter Daughtercell 1 Daughtercell 2 marker. cell 1 cell 2 What determines whether the differentiating daughter cell becomes an IPC or a neuron is not well 354 EMBO reports Vol 15 | No 4 | 2014 ª 2014 The Authors 354 EMBO reports Vol 15 | No 4 | 2014 understood. ª 2014 The Authors 3 Published online: March 17, 2014 EMBO reports Neurogenesis during vertebrate development Judith TML Paridaen & Wieland B Huttner A C Regulation of spindle orientation Symmetric division Planar Oblique Horizontal NPC 2 NPCs Mammalian neurogenesis Drosophila neuroblast Published online: March 17, 2014 EMBO reports Neurogenesis during vertebrate development Judith TML Paridaen & Wieland B Huttner A C Regulation of spindle orientation Symmetric division Planar Oblique Horizontal Apical CentrosomeNPC 2 NPCs Spindle Basal Mammalian neurogenesis Drosophila neuroblast Par3/Par6/aPKC ASPM LGN/NuMA/G Miranda/Numb Adherens junctions Cdk5rap2 Insc MCPH1 Lis1/Ndel1 Cell cortex Dynein B D Inheritance of fate determinants Asymmetric division Symmetric Asymmetric Asymmetric Mouse Zebrafish NPC 1 NPC + 1 Neuron Apical Centrosome Spindle Basal ASPM LGN/NuMA/G Splitting/ Par3/Par6/aPKC Miranda/Numb Regrowth? Adherens junctions Cdk5rap2 Insc MCPH1 Lis1/Ndel1 Cell cortex Dynein B D Inheritance of fate determinants Asymmetric division Symmetric Asymmetric Asymmetric NPC 1 NPC + 1 Neuron Mouse Zebrafish Splitting/ Regrowth? Notch Notch Notch Notch Notch Notch RGC RGC RGC IP Neuron RGC Neuron Apical Centrosome Cytoplasmic Basal Par3/Par6/aPKC Mother centriole MindbombNotch Ccnd2Notch Notch Notch Notch Notch Adherens junctions Daughter centriole NotchNumb RGC signalingTrim32RGC RGC IPandNeuron proneuralRGC Neuron bHLH Ciliary membrane Delta-likeApical 1 Centrosome Cytoplasmic Basal Staufen2 +Par3/Par6/aPKC mRNAs Mother centriole Mindbomb Ccnd2 Adherens junctions Daughter centriole Numb Trim32 Ciliary membranefactorsDelta-like 1 Apical E Centrosome inheritance F Notch signaling Staufen2 + mRNAs Par3/Par6/aPKC Apical E Centrosome inheritance Ngn2F Notch promotes signaling transcription of Delta, a ligand for Adherens junctions Par3/Par6/aPKC Notch, which is expressed in RGCs. Adherens junctions Centrosome ngn2 Centrosome ngn2 Mother centriole Mother centriole Notch signaling promotes transcription of Hes1, Daughter centriole Daughter centriole ngn2 which inhibits Ngn2ngn2 functions and promote the Ciliary membrane Ciliary membrane RGC fate. Cytoplasmic Cytoplasmic Mindbomb Mindbomb Cell surface Cell ngn2 cycle Cell Delta Hes1 Cell surface ngn2 ngn2 cycle Notch ngn2 Delta Hes1 ngn2 Activation Notch Inhibition ngn2 Delamination Activation Daughter Daughter Inhibition cell 1 cell 2 Delamination Daughter Daughter cell 1 cell 2 354 EMBO reports Vol 15 | No 4 | 2014 ª 2014 The Authors 354 EMBO reports Vol 15 | No 4 | 2014 ª 2014 The Authors 4 Notch signaling pathway 4 H. Shimojo et al. When Delta binds to Notch, �-secretase cleaves Notch, resulting in the release of intracellular domain (Notch-ICD) into the cytoplasm and into the nucleus. �-secretase Together with Rbpj and MAML, Notch activates transcription of downstream genes such as Hes1 and Hes5. Neuron Notch Signaling Oscillations in Neural Progenitors Hes inhibits proneural bHLH proteins. Shimojo et al. (2013) Fig. 1.2 The core pathway of Notch signaling. Proneural genes such as Ascl1 (also called Mash1)Hes inhibits its own expression and oscillates rapidly in a 1 Dynamic Notch Signaling 5 Hes5 occur before overt neuronal differentiation (Bettenhausen and Neurog2 (Ngn2) promote neuronal differentiation and induce the expression of Dll1, which in et al., 1995; Hatakeyama et al., 2004). We showed here that turn activates Notch signaling in neighboring cells. Notch is cleaved at the S1 site by Furin into reciprocaltwo manner with Ngn2 in neural progenitor cells. fragments that remain associated to form the functional heterodimer receptor consisting of the the Notch ligand Dll1 is expressed in an oscillatory manner by Notch extracellular domain and the transmembrane part. Upon activation of Notch, the Notch neural progenitors. It is likely that Dll1 oscillation mutually acti- intracellular domain (NICD) is released from the transmembrane domain and transferred to the vates Notch signalingNeuron in neighboring neural progenitors, thereby nucleus, where it forms a complex with the DNA-binding protein Rbpj and the transcriptionalIn differentiating cells, Hes expression disappears andmaintaining Ngn2Hes1 oscillation and these cells (Figure 8B). At one co-activator Maml. The NICD-Rbpj-Maml ternary complex induces the expression of transcrip- Notch Signaling Oscillations intime Neural point, Progenitors when the levels of Hes1 protein are high by activation tional repressor genes such as Hes1 a n d Hes5 . Hes1 and Hes5 repress the expression of proneuralexpression becomes sustained. of Notch signaling, those of Ngn2 and Dll1 expression are low genes and Dll1, thereby leading to the maintenance of neural progenitor cells (Figure 8B). About 1 hr later, the levels of Hes1 protein become low as a result of oscillation, leading to upregulation of Ngn2 et al. 2007 ) . Hes genes also repress the expression of Notch ligand genes. Notch and Dll1, which activates Notch signaling of neighboring cells ligand expression is induced by proneural genes, and therefore neurons (Figure 8B). Our data also showed that persistent Hes1 expres- express Notch ligands and inhibit neighboring cells to differentiate into neurons by Hes5 occur before overt neuronal differentiationsion in subsets (Bettenhausen of neural progenitors represses Dll1 expression activating Notch signaling. This process, called lateral inhibition, is essential to main- et al., 1995; Hatakeyama et al., 2004). Weand showed induces ectopic here that neuronal differentiation of the neighboring tain neural progenitor cells in the developing nervous system. In the absence of Notch the Notch ligand Dll1 is expressed in an oscillatorycells in the ventricularmanner by zone (Figure S10).
Load more

Recommended publications
  • Regulation of the Drosophila ID Protein Extra Macrochaetae by Proneural Dimerization Partners Ke Li1†, Nicholas E Baker1,2,3*
    RESEARCH ARTICLE Regulation of the Drosophila ID protein Extra macrochaetae by proneural dimerization partners Ke Li1†, Nicholas E Baker1,2,3* 1Department of Genetics, Albert Einstein College of Medicine, Bronx, United States; 2Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, United States; 3Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, United States Abstract Proneural bHLH proteins are transcriptional regulators of neural fate specification. Extra macrochaetae (Emc) forms inactive heterodimers with both proneural bHLH proteins and their bHLH partners (represented in Drosophila by Daughterless). It is generally thought that varying levels of Emc define a prepattern that determines where proneural bHLH genes can be effective. We report that instead it is the bHLH proteins that determine the pattern of Emc levels. Daughterless level sets Emc protein levels in most cells, apparently by stabilizing Emc in heterodimers. Emc is destabilized in proneural regions by local competition for heterodimer formation by proneural bHLH proteins including Atonal or AS-C proteins. Reflecting this post- translational control through protein stability, uniform emc transcription is sufficient for almost normal patterns of neurogenesis. Protein stability regulated by exchanges between bHLH protein *For correspondence: dimers could be a feature of bHLH-mediated developmental events. [email protected] DOI: https://doi.org/10.7554/eLife.33967.001 Present address: †Howard Hughes Medical Institute, Department of Physiology, University of California, San Introduction Francisco, San Francisco, United Proneural bHLH genes play a fundamental role in neurogenesis. Genes from Drosophila such as States atonal (ato) and genes of the Achaete-Scute gene complex (AS-C) define the proneural regions that Competing interests: The have the potential for neural fate (Baker and Brown, 2018; Bertrand et al., 2002; Go´mez- authors declare that no Skarmeta et al., 2003).
    [Show full text]
  • Hes6 Inhibits Astrocyte Differentiation and Promotes Neurogenesis Through Different Mechanisms
    The Journal of Neuroscience, October 25, 2006 • 26(43):11061–11071 • 11061 Cellular/Molecular Hes6 Inhibits Astrocyte Differentiation and Promotes Neurogenesis through Different Mechanisms Sumit Jhas, Sorana Ciura,* Stephanie Belanger-Jasmin,* Zhifeng Dong, Estelle Llamosas, Francesca M. Theriault, Kerline Joachim, Yeman Tang, Lauren Liu, Jisheng Liu, and Stefano Stifani Center for Neuronal Survival, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada H3A 2B4 The mechanisms regulating the generation of cell diversity in the mammalian cerebral cortex are beginning to be elucidated. In that regard, Hairy/Enhancer of split (Hes) 1 and 5 are basic helix-loop-helix (bHLH) factors that inhibit the differentiation of pluripotent cortical progenitors into neurons. In contrast, a related Hes family member termed Hes6 promotes neurogenesis. It is shown here that knockdown of endogenous Hes6 causes supernumerary cortical progenitors to differentiate into cells that exhibit an astrocytic morphol- ogy and express the astrocyte marker protein GFAP. Conversely, exogenous Hes6 expression in cortical progenitors inhibits astrocyte differentiation. The negative effect of Hes6 on astrocyte differentiation is independent of its ability to promote neuronal differentiation. We also show that neither its proneuronal nor its anti-gliogenic functions appear to depend on Hes6 ability to bind to DNA via the basic arm of its bHLH domain. Both of these activities require Hes6 to be localized to nuclei, but only its anti-gliogenic function depends on two short peptides, LNHLL and WRPW, that are conserved in all Hes6 proteins. These findings suggest that Hes6 is an important regulator of the neurogenic phase of cortical development by promoting the neuronal fate while suppressing astrocyte differentiation.
    [Show full text]
  • Regulation of Proneural Gene Expression and Cell Fate During Neuroblast Segregation in the Drosophila Embryo
    Development 114, 939-946 (1992) 939 Printed in Great Britain © The Company of Biologists Limited 1992 Regulation of proneural gene expression and cell fate during neuroblast segregation in the Drosophila embryo JAMES B. SKEATH and SEAN B. CARROLL* Howard Hughes Medical Institute, Laboratory of Molecular Biology, University of Wisconsin - Madison, 1525 Linden Drive, Madison, WI 53706, USA *To whom correspondence should be addressed Summary The Drosophila embryonic central nervous system expressed in a repeating pattern of four ectodermal cell develops from sets of progenitor neuroblasts which clusters per hemisegment. Even though 5-7 cells initially segregate from the neuroectoderm during early embryo- express ac in each cluster, only one, the neuroblast, genesis. Cells within this region can follow either the continues to express ac. The repression of ac in the neural or epidermal developmental pathway, a decision remaining cells of the cluster requires zygotic neurogenic guided by two opposing classes of genes. The proneural gene function. In embryos lacking any one of five genes, genes, including the members of the achaete-scute the restriction of ac expression to single cells does not complex (AS-C), promote neurogenesis, while the occur; instead, all cells of each cluster continue to neurogenic genes prevent neurogenesis and facilitate express ac, enlarge, delaminate and become neuroblasts. epidermal development. To understand the role that It appears that one key function of the neurogenic genes proneural gene expression and regulation play in the is to silence proneural gene expression within the choice between neurogenesis and epidermogenesis, we nonsegregating cells of the initial ectodermal clusters, examined the temporal and spatial expression pattern of thereby permitting epidermal development.
    [Show full text]
  • A Feedback Loop Mediated by Degradation of an Inhibitor Is Required to Initiate Neuronal Differentiation
    Downloaded from genesdev.cshlp.org on September 27, 2021 - Published by Cold Spring Harbor Laboratory Press A feedback loop mediated by degradation of an inhibitor is required to initiate neuronal differentiation Dorothy F. Sobieszczuk, Alexei Poliakov, Qiling Xu, and David G. Wilkinson1 Division of Developmental Neurobiology, MRC National Institute for Medical Research, London NW7 1AA, United Kingdom Neuronal differentiation is regulated by proneural genes that promote neurogenesis and inhibitory mechanisms that maintain progenitors. This raises the question of how the up-regulation of proneural genes required to initiate neurogenesis occurs in the presence of such inhibition. We carried out loss and gain of gene function, an interaction screen for binding partners, and biochemical analyses to uncover the regulation, developmental role, and mechanism of action of a ubiquitination adaptor protein, Btbd6a (BTB domain containing 6a). We find that the proneural gene neurog1 up-regulates btbd6a, which in turn is required for up-regulation of neurog1. Btbd6a is an adaptor for the Cul3 ubiquitin ligase complex, and we find that it binds to the transcriptional repressor Plzf (promyelocytic leukemia zinc finger). Btbd6a promotes the relocation of Plzf from nucleus to cytoplasm and targets Plzf for ubiquitination and degradation. plzfa is expressed widely in the neural epithelium; when overexpressed, it inhibits neurogenesis, and this inhibition is reversed by btbd6a. The antagonism of endogenous plzfa by btbd6a is required for neurogenesis, since the block in neuronal differentiation caused by btbd6a knockdown is alleviated by plzfa knockdown. These findings reveal a feedback loop mediated by degradation of an inhibitor that is essential for progenitors to undergo the transition to neuronal differentiation.
    [Show full text]
  • The Doublesex-Related Dmrta2 Safeguards Neural Progenitor
    The doublesex-related Dmrta2 safeguards neural PNAS PLUS progenitor maintenance involving transcriptional regulation of Hes1 Fraser I. Younga, Marc Keruzoreb,1, Xinsheng Nanc,1, Nicole Genneta, Eric J. Bellefroidb,2, and Meng Lia,c,2 aNeuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff CF24 4HQ, United Kingdom; bInstitute of Neuroscience, Université Libre de Bruxelles, B-6041 Gosselies, Belgium; and cSchool of Bioscience, Cardiff University, Cardiff CF24 4HQ, United Kingdom Edited by Anders Bjorklund, Lund University, Lund, Sweden, and approved May 16, 2017 (received for review March 29, 2017) The mechanisms that determine whether a neural progenitor cell onic brain, however (9, 10). Dmrta2 loss of function in zebrafish (NPC) reenters the cell cycle or exits and differentiates are pivotal for leads to significant reductions in cortical size, coupled with re- generating cells in the correct numbers and diverse types, and thus duced neuronal numbers (10, 11). Likewise, a smaller neocortex, dictate proper brain development. Combining gain-of-function and particularly the dorsomedial neocortex, has been observed in mice loss-of-function approaches in an embryonic stem cell-derived cortical carrying null deletions of Dmrta2 (12–14). Together with the as- differentiation model, we report that doublesex- and mab-3–related sociation of DMRTA2 mutation and microlissencephaly in humans, transcription factor a2 (Dmrta2, also known as Dmrt5) plays an im- these findings implicate Dmrta2 as an important regulator for cortical portant role in maintaining NPCs in the cell cycle. Temporally controlled neurogenesis. expression of transgenic Dmrta2 in NPCs suppresses differentiation Dmrta2-null mice also exhibit agenesis of the embryonic cor- Dmrta2 without affecting their neurogenic competence.
    [Show full text]
  • All in the Family: Proneural Bhlh Genes and Neuronal Diversity Nicholas E
    © 2018. Published by The Company of Biologists Ltd | Development (2018) 145, dev159426. doi:10.1242/dev.159426 REVIEW All in the family: proneural bHLH genes and neuronal diversity Nicholas E. Baker1,* and Nadean L. Brown2,* ABSTRACT lethal of scute [lsc,orl(1)sc] and asense (ase) – that are responsible Proneural basic Helix-Loop-Helix (bHLH) proteins are required for for development of much of the Drosophila CNS and PNS (Cubas neuronal determination and the differentiation of most neural et al., 1991; Garcia-Bellido and de Celis, 2009). Expression of these precursor cells. These transcription factors are expressed in vastly proneural genes defines regions of ectoderm with neurogenic divergent organisms, ranging from sponges to primates. Here, we competence, such that their default fate will be that of neural review proneural bHLH gene evolution and function in the Drosophila precursors unless diverted to another fate, for example by Notch and vertebrate nervous systems, arguing that the Drosophila gene signaling (Knust and Campos-Ortega, 1989; Simpson, 1990). ac, sc atonal provides a useful platform for understanding proneural gene and lsc are proneural genes, conferring proneural competence that structure and regulation. We also discuss how functional equivalency may or may not lead to neuronal determination in every cell, experiments using distinct proneural genes can reveal how proneural whereas ase is a neural precursor gene, expressed after the neural gene duplication and divergence are interwoven with neuronal fate decision has been made. It has been suggested that the complexity. vertebrate homologs of these genes are expressed in ectoderm with previously acquired neural character, and therefore are not true KEY WORDS: bHLH gene, Neural development, Neurogenesis, proneural genes (Bertrand et al., 2002).
    [Show full text]
  • The Role of Notch Signaling in Neurotransmitter Phenotype Specification in Enopusx Laevis
    W&M ScholarWorks Undergraduate Honors Theses Theses, Dissertations, & Master Projects 5-2009 The Role of Notch Signaling in Neurotransmitter Phenotype Specification in enopusX Laevis Michael S. Harper College of William and Mary Follow this and additional works at: https://scholarworks.wm.edu/honorstheses Recommended Citation Harper, Michael S., "The Role of Notch Signaling in Neurotransmitter Phenotype Specification in enopusX Laevis" (2009). Undergraduate Honors Theses. Paper 293. https://scholarworks.wm.edu/honorstheses/293 This Honors Thesis is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Undergraduate Honors Theses by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. 1 Acknowledgments I would like to gratefully acknowledge Matt Wester, Rebecca Lowdon, and all the members of the Saha lab for advice, assistance, and engaging discussions. I would also like to thank my family for supporting me, and the members my committee. Most of all I would like to thank Dr. Margaret Saha, not only for mentoring me during this project but for providing me with the opportunity to do undergraduate research. Funding was provided by the Arnold and Mabel Beckman Foundation, The Howard Hughes Medical Institute Science Research Education Program Grant to the College of William and Mary, and a National Science Foundation grant to M.S.S. 2 Table of Contents Title Page…………………………………………………………………………………..i
    [Show full text]
  • Proneural Genes and the Specification of Neural Cell Types
    REVIEWS PRONEURAL GENES AND THE SPECIFICATION OF NEURAL CELL TYPES Nicolas Bertrand*, Diogo S. Castro* and François Guillemot Certain morphological, physiological and molecular characteristics are shared by all neurons. However, despite these similarities, neurons constitute the most diverse cell population of any organism. Recently, considerable attention has been focused on identifying the molecular mechanisms that underlie this cellular diversity. Parallel studies in Drosophila and vertebrates have revealed that proneural genes are key regulators of neurogenesis, coordinating the acquisition of a generic neuronal fate and of specific subtype identities that are appropriate for the location and time of neuronal generation. These studies reveal that, in spite of differences between invertebrate and vertebrate neural lineages, Drosophila and vertebrate proneural genes have remarkably similar roles. BASIC HELIX–LOOP–HELIX Building a nervous system involves the production of a ‘proneural genes’,which encode transcription factors of A structural motif that is present vast array of neuronal and glial cell types that must be the BASIC HELIX–LOOP–HELIX (bHLH) class, are both neces- in many transcription factors, produced in the correct numbers and at appropriate sary and sufficient, in the context of the ectoderm, which is characterized by two positions. The uniform epithelial sheath that constitutes to initiate the development of neuronal lineages and to α-helices separated by a loop. The helices mediate the primordium of the nervous system in invertebrate promote the generation of progenitors that are com- dimerization, and the adjacent and vertebrate embryos consists of cells that have the mitted to differentiation. Importantly, proneural genes basic region is required for DNA potential to generate both neurons and glia.
    [Show full text]
  • Cenpj/CPAP Regulates Progenitor Divisions and Neuronal Migration in the Cerebral Cortex Downstream of Ascl1
    ARTICLE Received 28 Mar 2014 | Accepted 30 Jan 2015 | Published 10 Mar 2015 DOI: 10.1038/ncomms7474 OPEN Cenpj/CPAP regulates progenitor divisions and neuronal migration in the cerebral cortex downstream of Ascl1 Patricia P. Garcez1, Javier Diaz-Alonso2, Ivan Crespo-Enriquez3, Diogo Castro1,w, Donald Bell4 & Franc¸ois Guillemot1 The proneural factor Ascl1 controls multiple steps of neurogenesis in the embryonic brain, including progenitor division and neuronal migration. Here we show that Cenpj, also known as CPAP, a microcephaly gene, is a transcriptional target of Ascl1 in the embryonic cerebral cortex. We have characterized the role of Cenpj during cortical development by in utero electroporation knockdown and found that silencing Cenpj in the ventricular zone disrupts centrosome biogenesis and randomizes the cleavage plane orientation of radial glia pro- genitors. Moreover, we show that downregulation of Cenpj in post-mitotic neurons increases stable microtubules and leads to slower neuronal migration, abnormal centrosome position and aberrant neuronal morphology. Moreover, rescue experiments shows that Cenpj mediates the role of Ascl1 in centrosome biogenesis in progenitor cells and in microtubule dynamics in migrating neurons. These data provide insights into genetic pathways controlling cortical development and primary microcephaly observed in humans with mutations in Cenpj. 1 Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK. 2 Department of Biochemistry and Molecular Biology I, School of Biology and Instituto Universitario de Investigaciones Neuroquı´micas (IUIN), Complutense University, 28040 Madrid, Spain. 3 Department of Craniofacial Development & Stem Cell Biology, King’s College London, Guy’s Tower Wing, Floor 27, London SE1 9RT, UK.
    [Show full text]
  • Emc, a Negative HLH Regulator with Multiple Functions in Drosophila Development
    Oncogene (2001) 20, 8299 ± 8307 ã 2001 Nature Publishing Group All rights reserved 0950 ± 9232/01 $15.00 www.nature.com/onc Emc, a negative HLH regulator with multiple functions in Drosophila development Sonsoles Campuzano*,1 1Centro de BiologõÂa Molecular Severo Ochoa, Cantoblanco, 28049 Madrid, Spain Expression and functional analyses of Emc have which by their own do not alter the pattern of SOs, a demonstrated that it is a prototype for a protein required recessive mutation in a gene encoding a repressor of for multiple processes in development. Initially char- AS-C would become dominant and promote the acterized as a negative regulator of sensory organ generation of extra SOs. That is, only one copy of development, it was later found to regulate many other that gene would not produce enough protein to repress developmental processes and cell proliferation. Its ability several copies of AS-C and allow a normal pattern of to block the function of bHLH proteins by forming SOs. Mutations that ful®lled this criterion were found heterodimers, which are ineective in DNA binding, in two loci: hairy (h) and the novel emc (Botas et al., accounts for the role of Emc in preventing the acquisition 1982). It was further observed that loss of emc of several cell fates which are under the control of bHLH function, in a wild type background for the AS-C, proteins. However, while maintaining this repressive caused development of extra SOs, whereas AS-C molecular mechanism, emc also appears to act as a de®ciencies suppressed this phenotype (Moscoso del positive regulator of dierentiation.
    [Show full text]
  • Differential Actions of the Proneural Genes Encoding Mash1 and Neurogenins in Nurr1-Induced Dopamine Neuron Differentiation
    2310 Research Article Differential actions of the proneural genes encoding Mash1 and neurogenins in Nurr1-induced dopamine neuron differentiation Chang-Hwan Park1,2,*, Jin Sun Kang1,2,*, Jae-Sang Kim3, Seungsoo Chung4, Jin-Young Koh4, Eun-Hye Yoon1,2, A. Young Jo2,5, Mi-Yoon Chang2,5, Hyun-Chul Koh2,6, SeJin Hwang7, Haeyoung Suh-Kim8, Yong-Sung Lee2,5, Kwang-Soo Kim9 and Sang-Hun Lee2,5,‡ 1Department of Microbiology and 2Institute of Mental Health, Hanyang University, Seoul 133-791, Korea 3Division of Molecular Life Sciences, Ewha Womans University, Seoul, 120-750, Korea 4Department of Physiology, College of Medicine, Yonsei University, Seoul 120-752, Korea 5Department of Biochemistry and Molecular Biology and 6Department of Pharmacology, Hanyang University, Seoul 133-791, Korea 7Department of Anatomy and Cell Biology, College of Medicine, Hanyang University, Seoul 133-791, Korea 8Department of Anatomy and Brain Disease Research Center, College of Medicine, Ajou University, Suwon 442-749, Korea 9Molecular Neurobiology Laboratory; McLean Hospital/Harvard Medical School, Belmont, MA, 02478, USA *These authors contributed equally to this work ‡Author for correspondence (e-mail: [email protected]) Accepted 23 February 2006 Journal of Cell Science 119, 2310-2320 Published by The Company of Biologists 2006 doi:10.1242/jcs.02955 Summary The steroid receptor-type transcription factor Nurr1 has a Ngn2 and NeuroD, repressed Nurr1-induced expression of crucial role in the development of the mesencephalic DA neuronal markers. Domain-swapping experiments with dopamine (DA) neurons. Although ectopic expression of Mash1 and NeuroD indicated that the helix-loop-helix Nurr1 in cultured neural precursor cells is sufficient in domain, responsible for mediating dimerization of bHLH establishing the DA phenotype, Nurr1-induced DA cells are transcription factors, imparts the distinct effect.
    [Show full text]
  • RAS/ERK Signaling Controls Proneural Genetic Programs in Cortical Development and Gliomagenesis
    The Journal of Neuroscience, February 5, 2014 • 34(6):2169–2190 • 2169 Neurobiology of Disease RAS/ERK Signaling Controls Proneural Genetic Programs in Cortical Development and Gliomagenesis Saiqun Li,1,4,5* Pierre Mattar,1,4,5* Rajiv Dixit,1,4,5* Samuel O. Lawn,2,4,5,6 Grey Wilkinson,1,4,5 Cassandra Kinch,1,4,5 David Eisenstat,7 Deborah M. Kurrasch,3,4,5 Jennifer A. Chan,2,4,5,6 and Carol Schuurmans1,4,5 1Departments of Biochemistry and Molecular Biology, 2Departments of Pathology and Laboratory Medicine, 3Department of Medical Genetics, 4Hotchkiss Brain Institute, 5Alberta Children’s Hospital Research Institute, and 6Southern Alberta Cancer Research Institute, University of Calgary, Calgary, Alberta, Canada, T2N 4N1, and 7Departments of Pediatrics and Medical Genetics, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7 Neuralcellfatespecificationiswellunderstoodintheembryoniccerebralcortex,wheretheproneuralgenesNeurog2andAscl1arekeycell fate determinants. What is less well understood is how cellular diversity is generated in brain tumors. Gliomas and glioneuronal tumors, which are often localized in the cerebrum, are both characterized by a neoplastic glial component, but glioneuronal tumors also have an intermixed neuronal component. A core abnormality in both tumor groups is overactive RAS/ERK signaling, a pro-proliferative signal whose contributions to cell differentiation in oncogenesis are largely unexplored. We found that RAS/ERK activation levels differ in two distinct human tumors associated with constitutively active BRAF. Pilocytic astrocytomas, which contain abnormal glial cells, have higher ERK activation levels than gangliogliomas, which contain abnormal neuronal and glial cells. Using in vivo gain of function and loss of function in the mouse embryonic neocortex, we found that RAS/ERK signals control a proneural genetic switch, inhibiting Neurog2 expression while inducing Ascl1, a competing lineage determinant.
    [Show full text]