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Magno L, Asgarian Z, Pendolino V, Velona T, Mackintosh A, Lee F, Stryjewska A, Zimmer C, Guillemot F, Farrant M, Clark B, Kessaris N. Transient developmental imbalance of cortical interneuron subtypes presages long-term changes in behavior. Cell Rep 2021; 35:109249. [PMID: 34133916 PMCID: PMC8220254 DOI: 10.1016/j.celrep.2021.109249] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 04/02/2021] [Accepted: 05/22/2021] [Indexed: 11/16/2022] Open
Abstract
Cortical GABAergic interneurons are generated in large numbers in the ganglionic eminences and migrate into the cerebral cortex during embryogenesis. At early postnatal stages, during neuronal circuit maturation, autonomous and activity-dependent mechanisms operate within the cortex to adjust cell numbers by eliminating naturally occurring neuron excess. Here, we show that when cortical interneurons are generated in aberrantly high numbers-due to a defect in precursor cell proliferation during embryogenesis-extra parvalbumin interneurons persist in the postnatal mouse cortex during critical periods of cortical network maturation. Even though cell numbers are subsequently normalized, behavioral abnormalities remain in adulthood. This suggests that timely clearance of excess cortical interneurons is critical for correct functional maturation of circuits that drive adult behavior.
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Affiliation(s)
- Lorenza Magno
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK; Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Zeinab Asgarian
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK; Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Valentina Pendolino
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Theodora Velona
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Albert Mackintosh
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Flora Lee
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Agata Stryjewska
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK; Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Celine Zimmer
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | | | - Mark Farrant
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Beverley Clark
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK; Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Nicoletta Kessaris
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK; Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
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Poulin JF, Luppi MP, Hofer C, Caronia G, Hsu PK, Chan CS, Awatramani R. PRISM: A Progenitor-Restricted Intersectional Fate Mapping Approach Redefines Forebrain Lineages. Dev Cell 2021; 53:740-753.e3. [PMID: 32574593 DOI: 10.1016/j.devcel.2020.05.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 03/24/2020] [Accepted: 05/15/2020] [Indexed: 01/08/2023]
Abstract
Lineage tracing aims to identify the progeny of a defined population of dividing progenitor cells, a daunting task in the developing central nervous system where thousands of cell types are generated. In mice, lineage analysis has been accomplished using Cre recombinase to indelibly label a defined progenitor population and its progeny. However, the interpretation of historical recombination events is hampered by the fact that driver genes are often expressed in both progenitors and postmitotic cells. Genetically inducible approaches provide temporal specificity but are afflicted by mosaicism and toxicity. Here, we present PRISM, a progenitor-restricted intersectional fate mapping approach in which Flp recombinase expression is both dependent on Cre and restricted to neural progenitors, thus circumventing the aforementioned confounds. This tool can be used in conjunction with existing Cre lines making it broadly applicable. We applied PRISM to resolve two developmentally important, but contentious, lineages-Shh and Cux2.
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Affiliation(s)
- Jean-François Poulin
- Department of Neurology and Neurosurgery, Faculty of Medicine, McGill University Montreal, Quebec H3A 0G4, Canada
| | - Milagros Pereira Luppi
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Caitlyn Hofer
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Giuliana Caronia
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Pei-Ken Hsu
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - C Savio Chan
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Rajeshwar Awatramani
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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Yang H, Kim J, Kim Y, Jang SW, Sestan N, Shim S. Cux2 expression regulated by Lhx2 in the upper layer neurons of the developing cortex. Biochem Biophys Res Commun 2020; 521:874-879. [PMID: 31708105 DOI: 10.1016/j.bbrc.2019.11.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 11/01/2019] [Indexed: 12/20/2022]
Abstract
The laminar structure, a unique feature of the mammalian cerebrum, is formed by a number of genes in a highly complex process. The pyramidal neurons that make up each layer of the cerebrum are functionally characterized by specific gene expressions. In particular, Cux1 and Cux2, which are specifically expressed in layer II-IV neurons, are known to regulate dendritic branching, spine morphology, and synapse formation. However, it is still unknown how their expression is regulated transcriptionally. Here we constructed Cux2-mCherry transgenic mice that reproduce the cortical layer II-IV-specific expression of Cux2, a member of the Cut/Cux/CDP family, using BAC transgenesis and a variety of coordinated cortical layer markers that are known to date. Our immunohistochemistry analysis shows that mCherry was expressed in cortical layer II-IV and the corpus callosum in the same way as endogenous Cux2 without ectopic expression. We also identified a region of 220 bp that is highly conserved in mammals and controls specific cerebral expression of Cux2, using comparative genome analysis and in vivo reporter assays. Furthermore, we confirm that Lhx2, whose expression in cortical layer II-IV is similar to that of the Cux2 enhancer, can act as a transcriptional activator. These results suggest that cortical layer II-IV expression of Cux2 can be regulated by the interaction of Cux2-E1 and Lhx2, and that their failure to co-regulate is associated with neurodevelopmental disorders such as autism and schizophrenia.
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Affiliation(s)
- Hayoung Yang
- Department of Biochemistry, Chungbuk National University, Cheongju, 28644, Republic of Korea
| | - Jiwoo Kim
- Department of Biochemistry, Chungbuk National University, Cheongju, 28644, Republic of Korea
| | - Yujin Kim
- Department of Biochemistry, Chungbuk National University, Cheongju, 28644, Republic of Korea
| | - Sung-Wuk Jang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, 05505, Republic of Korea
| | - Nenad Sestan
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale School of Medicine, New Haven, CT, 06510, USA.
| | - Sungbo Shim
- Department of Biochemistry, Chungbuk National University, Cheongju, 28644, Republic of Korea.
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Iulianella A, Wingate RJ, Moens CB, Capaldo E. The generation of granule cells during the development and evolution of the cerebellum. Dev Dyn 2019; 248:506-513. [PMID: 31131952 DOI: 10.1002/dvdy.64] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/10/2019] [Accepted: 05/16/2019] [Indexed: 12/19/2022] Open
Abstract
The cerebellum coordinates vestibular input into the hindbrain to control balance and movement, and its anatomical complexity is increasingly viewed as a high-throughput processing center for sensory and cognitive functions. Cerebellum development however is relatively simple, and arises from a specialized structure in the anterior hindbrain called the rhombic lip, which along with the ventricular zone of the rostral-most dorsal hindbrain region, give rise to the distinct cell types that constitute the cerebellum. Granule cells, being the most numerous cell types, arise from the rhombic lip and form a dense and distinct layer of the cerebellar cortex. In this short review, we describe the various strategies used by amniotes and anamniotes to generate and diversify granule cell types during cerebellar development.
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Affiliation(s)
- Angelo Iulianella
- Department of Medical Neuroscience and Brain Repair Centre, Life Science Research Institute, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Richard J Wingate
- MRC Centre of Neurodevelopmental Disorders, King's College London, London, UK
| | - Cecilia B Moens
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Emily Capaldo
- Department of Medical Neuroscience and Brain Repair Centre, Life Science Research Institute, Dalhousie University, Halifax, Nova Scotia, Canada
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Fregoso SP, Dwyer BE, Franco SJ. Lmx1a drives Cux2 expression in the cortical hem through activation of a conserved intronic enhancer. Development 2019; 146:dev.170068. [PMID: 30770393 DOI: 10.1242/dev.170068] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 02/11/2019] [Indexed: 01/06/2023]
Abstract
During neocortical development, neurons are produced by a diverse pool of neural progenitors. A subset of progenitors express the Cux2 gene and are fate restricted to produce certain neuronal subtypes; however, the upstream pathways that specify these progenitor fates remain unknown. To uncover the transcriptional networks that regulate Cux2 expression in the forebrain, we characterized a conserved Cux2 enhancer that recapitulates Cux2 expression specifically in the cortical hem. Using a bioinformatic approach, we identified putative transcription factor (TF)-binding sites for cortical hem-patterning TFs. We found that the homeobox TF Lmx1a can activate the Cux2 enhancer in vitro Furthermore, we showed that Lmx1a-binding sites were required for enhancer activity in the cortical hem in vivo Mis-expression of Lmx1a in hippocampal progenitors caused an increase in Cux2 enhancer activity outside the cortical hem. Finally, we compared several human enhancers with cortical hem-restricted activity and found that recurrent Lmx1a-binding sites are a top shared feature. Uncovering the network of TFs involved in regulating Cux2 expression will increase our understanding of the mechanisms pivotal in establishing Cux2 lineage fates in the developing forebrain.
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Affiliation(s)
- Santiago P Fregoso
- Graduate Program in Cell Biology, Stem Cells and Development, University of Colorado Graduate School - Anschutz Medical Campus, Aurora, CO 80045, USA.,Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine - Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Brett E Dwyer
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine - Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Santos J Franco
- Graduate Program in Cell Biology, Stem Cells and Development, University of Colorado Graduate School - Anschutz Medical Campus, Aurora, CO 80045, USA .,Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine - Anschutz Medical Campus, Aurora, CO 80045, USA
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Ueda S, Cordeiro IR, Moriyama Y, Nishimori C, Kai KI, Yu R, Nakato R, Shirahige K, Tanaka M. Cux2 refines the forelimb field by controlling expression of Raldh2 and Hox genes. Biol Open 2019; 8:bio.040584. [PMID: 30651234 PMCID: PMC6398465 DOI: 10.1242/bio.040584] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In vertebrates, two pairs of buds that give rise to the fore- and hindlimbs form at discrete positions along the rostral-caudal axis of the body. The mechanism responsible for the positioning of the limb buds is still largely unknown. Here we show a novel function for Cut homeobox transcription factor 2 (Cux2), the ortholog of Drosophila cut, in refining the forelimb field during chick development. Cux2 is expressed in the forelimb field before the emergence of the limb buds. Knocking down the expression of Cux2 using small interfering RNA (siRNA) resulted in a caudal shift of the forelimb bud, whereas misexpression of Cux2 or the constitutively active Cux2-VP16 caused a rostral shift of the forelimb bud or reduction of the forelimb field along the anterior-posterior axis. Further functional analyses revealed that expression of Hoxb genes and retinaldehyde dehydrogenase 2 (Raldh2), which are involved in limb positioning, are directly activated by Cux2 in the lateral plate mesoderm. Our data suggest that Cux2 in the lateral plate mesoderm refines the forelimb field via regulation of Raldh2 and Hoxb genes in chicken embryos. Summary: Cux2 in the lateral plate mesoderm refines the forelimb field via regulation of Raldh2 and Hoxb genes in chicken embryos.
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Affiliation(s)
- Shogo Ueda
- Department of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, 226-8501, Japan
| | - Ingrid Rosenburg Cordeiro
- Department of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, 226-8501, Japan
| | - Yuuta Moriyama
- Department of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, 226-8501, Japan
| | - Chika Nishimori
- Department of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, 226-8501, Japan
| | - Kei-Ichi Kai
- Department of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, 226-8501, Japan
| | - Reiko Yu
- Department of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, 226-8501, Japan
| | - Ryoichiro Nakato
- Research Center for Epigenetic Disease, Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Katsuhiko Shirahige
- Research Center for Epigenetic Disease, Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Mikiko Tanaka
- Department of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, 226-8501, Japan
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Abstract
Cux1 and Cux2 are the vertebrate members of a family of homeodomain transcription factors (TF) containing Cut repeat DNA-binding sequences. Perturbation of their expression has been implicated in a wide variety of diseases and disorders, ranging from cancer to autism spectrum disorder (ASD). Within the nervous system, both genes are expressed during neurogenesis and in specific neuronal subpopulations. Their role during development and circuit specification is discussed here, with a particular focus on the cortex where their restricted expression in pyramidal neurons of the upper layers appears to be responsible for many of the specialized functions of these cells, and where their functions have been extensively investigated. Finally, we discuss how Cux TF represent a promising avenue for manipulating neuronal function and for reprogramming.
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Dwyer ND, Chen B, Chou SJ, Hippenmeyer S, Nguyen L, Ghashghaei HT. Neural Stem Cells to Cerebral Cortex: Emerging Mechanisms Regulating Progenitor Behavior and Productivity. J Neurosci 2016; 36:11394-401. [PMID: 27911741 DOI: 10.1523/JNEUROSCI.2359-16.2016] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/23/2016] [Accepted: 08/30/2016] [Indexed: 12/16/2022] Open
Abstract
This review accompanies a 2016 SFN mini-symposium presenting examples of current studies that address a central question: How do neural stem cells (NSCs) divide in different ways to produce heterogeneous daughter types at the right time and in proper numbers to build a cerebral cortex with the appropriate size and structure? We will focus on four aspects of corticogenesis: cytokinesis events that follow apical mitoses of NSCs; coordinating abscission with delamination from the apical membrane; timing of neurogenesis and its indirect regulation through emergence of intermediate progenitors; and capacity of single NSCs to generate the correct number and laminar fate of cortical neurons. Defects in these mechanisms can cause microcephaly and other brain malformations, and understanding them is critical to designing diagnostic tools and preventive and corrective therapies.
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Yamada M, Clark J, McClelland C, Capaldo E, Ray A, Iulianella A. Cux2 activity defines a subpopulation of perinatal neurogenic progenitors in the hippocampus. Hippocampus 2014; 25:253-67. [PMID: 25252086 PMCID: PMC4312975 DOI: 10.1002/hipo.22370] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2014] [Indexed: 11/22/2022]
Abstract
The hippocampus arises from the medial region of the subventricular (SVZ) within the telencephalon. It is one of two regions in the postnatal brain that harbors neural progenitors (NPs) capable of giving rise to new neurons. Neurogenesis in the hippocampus is restricted to the subgranular zone (SGZ) of the dentate gyrus (DG) where it contributes to the generation of granule cell layer (gcl) neurons. It is thought that SGZ progenitors are heterogeneous, differing in their morphology, expression profiles, and developmental potential, however it is currently unknown whether they display differences in their developmental origins and cell fate-restriction in the DG. Here we demonstrate that Cux2 is a marker for SGZ progenitors and nascent granule cell neurons in the perinatal brain. Cux2 was expressed in the presumptive hippocampal forming region of the embryonic forebrain from E14.5 onwards. At fetal stages, Cux2 was expressed in early-forming Prox1+ granule cell neurons as well as the SVZ of the DG germinal matrix. In the postnatal brain, Cux2 was expressed in several types of progenitors in the SGZ of the DG, including Nestin/Sox2 double-positive radial glia, Sox2+ cells that lacked a radial glial process, DCX+ neuroblasts, and Calretinin-expressing nascent neurons. Another domain characterized by a low level of Cux2 expression emerged in Calbindin+ neurons of the developing DG blades. We used Cux2-Cre mice in genetic fate-mapping studies and showed almost exclusive labeling of Calbindin-positive gcl neurons, but not in any progenitor cell types or astroglia. This suggests that Cux2+ progenitors directly differentiate into gcl neurons and do not self-renew. Interestingly, developmental profiling of cell fate revealed an outside-in formation of gcl neurons in the DG, likely reflecting the activity of Cux2 in the germinative matrices during DG formation and maturation. However, DG morphogenesis proceeded largely normally in hypomorphic Cux2 mutants lacking Cux2 expression. Taken together we conclude that Cux2 expression reflects hippocampal neurogenesis and identifies non-self-renewing NPs in the SGZ.
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Affiliation(s)
- Makiko Yamada
- Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, Life Science Research Institute, Halifax, Nova Scotia, Canada
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Wittmann W, Iulianella A, Gunhaga L. Cux2 acts as a critical regulator for neurogenesis in the olfactory epithelium of vertebrates. Dev Biol 2014; 388:35-47. [PMID: 24512687 DOI: 10.1016/j.ydbio.2014.01.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 01/30/2014] [Accepted: 01/31/2014] [Indexed: 01/17/2023]
Abstract
Signaling pathways and transcription factors are crucial regulators of vertebrate neurogenesis, exerting their function in a spatial and temporal manner. Despite recent advances in our understanding of the molecular regulation of embryonic neurogenesis, little is known regarding how different signaling pathways interact to tightly regulate this process during the development of neuroepithelia. To address this, we have investigated the events lying upstream and downstream of a key neurogenic factor, the Cut-like homeodomain transcription factor-2 (Cux2), during embryonic neurogenesis in chick and mouse. By using the olfactory epithelium as a model for neurogenesis we have analyzed mouse embryos deficient in Cux2, as well as chick embryos exposed to Cux2 silencing (si) RNA or a Cux2 over-expression construct. We provide evidence that enhanced BMP activity increases Cux2 expression and suppresses olfactory neurogenesis in the chick olfactory epithelium. In addition, our results show that up-regulation of Cux2, either BMP-induced or ectopically over-expressed, reduce Delta1 expression and suppress proliferation. Interestingly, the loss of Cux2 activity, using mutant mice or siRNA in chick, also diminishes neurogenesis, Notch activity and cell proliferation in the olfactory epithelium. Our results suggest that controlled low levels of Cux2 activity are necessary for proper Notch signaling, maintenance of the proliferative pool and ongoing neurogenesis in the olfactory epithelium. Thus, we demonstrate a novel conserved mechanism in vertebrates in which levels of Cux2 activity play an important role for ongoing neurogenesis in the olfactory epithelium.
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Affiliation(s)
- Walter Wittmann
- Umeå Centre for Molecular Medicine, Umeå University, Building 6M 4th floor, 901 87 Umeå, Sweden.
| | - Angelo Iulianella
- Department of Medical Neuroscience, Dalhousie University, Halifax, Canada.
| | - Lena Gunhaga
- Umeå Centre for Molecular Medicine, Umeå University, Building 6M 4th floor, 901 87 Umeå, Sweden.
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Fugistier P, Vallet PG, Leuba G, Piotton F, Marin P, Bouras C, Savioz A. Comparison of frailty of primary neurons, embryonic, and aging mouse cortical layers. Neurobiol Aging 2014; 35:322-30. [PMID: 24011540 DOI: 10.1016/j.neurobiolaging.2013.08.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 05/02/2013] [Accepted: 08/05/2013] [Indexed: 11/23/2022]
Abstract
Superficial layers I to III of the human cerebral cortex are more vulnerable toward Aβ peptides than deep layers V to VI in aging. Three models of layers were used to investigate this pattern of frailty. First, primary neurons from E14 and E17 embryonic murine cortices, corresponding respectively to future deep and superficial layers, were treated either with Aβ(1-42), okadaic acid, or kainic acid. Second, whole E14 and E17 embryonic cortices, and third, in vitro separated deep and superficial layers of young and old C57BL/6J mice, were treated identically. We observed that E14 and E17 neurons in culture were prone to death after the Aβ and particularly the kainic acid treatment. This was also the case for the superficial layers of the aged cortex, but not for the embryonic, the young cortex, and the deep layers of the aged cortex. Thus, the aged superficial layers appeared to be preferentially vulnerable against Aβ and kainic acid. This pattern of vulnerability corresponds to enhanced accumulation of senile plaques in the superficial cortical layers with aging and Alzheimer's disease.
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Cubelos B, Nieto M. Intrinsic programs regulating dendrites and synapses in the upper layer neurons of the cortex. Commun Integr Biol 2010; 3:483-6. [PMID: 21331220 DOI: 10.4161/cib.3.6.12755] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 06/18/2010] [Indexed: 11/19/2022] Open
Abstract
Dendrites and spines are key regulators of neuronal function often affected in cognitive disorders. Neuronal subclasses are characterized by a wide range of dendritic morphologies that aid their specific functions. However, how subclass-specific dendritic trees arise during vertebrate development remains largely unknown. We have recently reported that the restricted expression of Cux1 and Cux2 genes in the upper layers of the cerebral cortex determines the specific morphology of dendrites and spines and the function of these neurons. Since Cux genes are the vertebrate homologs of Drosophila Cut, which specifies the dendritic morphologies of certain sensory neuron populations, our findings suggest that mechanisms of dendrite differentiation are conserved between Drosophila and mammals, which had yet to be demonstrated. Importantly, we found that Cux genes not only modulate dendritic branching, but also dendritic spine morphogenesis, the functional synapse and cognition. Dendritic spine stabilization was partly mediated by direct repression of genes of the Xlr family, previously implicated in cognitive defects in a model of Turner syndrome. Hence, our work indicates that neuronal subclass specific determinants may intrinsically affect synaptic activity beyond expected. The functions of Cux1 and Cux2 were additive and complement each other to establish the final pattern of the dendritic tree and the number and strength of the synapses. This work unravels novel mechanisms of dendritogenesis and synaptogenesis and illustrates how regulating dendritic structures contributes to the specialization of upper layer neurons. It will be interesting to dissect how these mechanisms regulate cortical activity, area specialization and cognitive functions.
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Affiliation(s)
- Beatriz Cubelos
- Centro Nacional de Biotecnología; CSIC; Campus de Cantoblanco; Madrid, Spain
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