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Narbonne-Reveau K, Erni A, Eichner N, Sankar S, Kapoor S, Meister G, Cremer H, Maurange C, Beclin C. In vivo AGO-APP identifies a module of microRNAs cooperatively preserving neural progenitors. PLoS Genet 2025; 21:e1011680. [PMID: 40299997 PMCID: PMC12064045 DOI: 10.1371/journal.pgen.1011680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/09/2025] [Accepted: 04/07/2025] [Indexed: 05/01/2025] Open
Abstract
MicroRNAs are essential regulators of gene expression. Their function is particularly important during neurogenesis, when the production of large numbers of neurons from a limited number of neural stem cells depends on the precise control of determination, proliferation and differentiation. However, microRNAs can target many mRNAs and vice-versa, raising the question of how specificity is achieved to elicit a precise regulatory response. Here we introduce in vivo AGO-APP, a novel approach to purify Argonaute-bound, and therefore active microRNAs from specific cell types. Using AGO-APP in the larval Drosophila central nervous system, we identify a module of microRNAs predicted to redundantly target all iconic genes known to control the transition from neuroblasts to neurons. While microRNA overexpression generally validated predictions, knockdown of individual microRNAs did not induce detectable phenotypes. In contrast, neuroblasts were induced to differentiate precociously when several microRNAs were knocked down simultaneously. Our data supports the concept that at physiological expression levels, the cooperative action of miRNAs allows efficient targeting of entire gene networks.
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Affiliation(s)
- Karine Narbonne-Reveau
- Aix-Marseille Université, Centre National pour la Recherche Scientifique (CNRS), Institut de Biologie du Développement de Marseille (IBDM), Marseille, France
- Equipe labellisée Ligue contre le Cancer, Marseille, France,
| | - Andrea Erni
- Aix-Marseille Université, Centre National pour la Recherche Scientifique (CNRS), Institut de Biologie du Développement de Marseille (IBDM), Marseille, France
| | - Norbert Eichner
- Regensburg Center for Biochemistry (RCB), University of Regensburg, Regensburg, Germany
| | - Shobana Sankar
- Aix-Marseille Université, Centre National pour la Recherche Scientifique (CNRS), Institut de Biologie du Développement de Marseille (IBDM), Marseille, France
- Equipe labellisée Ligue contre le Cancer, Marseille, France,
| | - Surbhi Kapoor
- Aix-Marseille Université, Centre National pour la Recherche Scientifique (CNRS), Institut de Biologie du Développement de Marseille (IBDM), Marseille, France
| | - Gunter Meister
- Regensburg Center for Biochemistry (RCB), University of Regensburg, Regensburg, Germany
| | - Harold Cremer
- Aix-Marseille Université, Centre National pour la Recherche Scientifique (CNRS), Institut de Biologie du Développement de Marseille (IBDM), Marseille, France
| | - Cédric Maurange
- Aix-Marseille Université, Centre National pour la Recherche Scientifique (CNRS), Institut de Biologie du Développement de Marseille (IBDM), Marseille, France
- Equipe labellisée Ligue contre le Cancer, Marseille, France,
| | - Christophe Beclin
- Aix-Marseille Université, Centre National pour la Recherche Scientifique (CNRS), Institut de Biologie du Développement de Marseille (IBDM), Marseille, France
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2
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Nguyen PK, Cheng LY. Drosophila medulla neuroblast termination via apoptosis, differentiation, and gliogenic switch is scheduled by the depletion of the neuroepithelial stem cell pool. eLife 2024; 13:e96876. [PMID: 38905123 PMCID: PMC11262793 DOI: 10.7554/elife.96876] [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: 02/22/2024] [Accepted: 06/20/2024] [Indexed: 06/23/2024] Open
Abstract
The brain is consisted of diverse neurons arising from a limited number of neural stem cells. Drosophila neural stem cells called neuroblasts (NBs) produces specific neural lineages of various lineage sizes depending on their location in the brain. In the Drosophila visual processing centre - the optic lobes (OLs), medulla NBs derived from the neuroepithelium (NE) give rise to neurons and glia cells of the medulla cortex. The timing and the mechanisms responsible for the cessation of medulla NBs are so far not known. In this study, we show that the termination of medulla NBs during early pupal development is determined by the exhaustion of the NE stem cell pool. Hence, altering NE-NB transition during larval neurogenesis disrupts the timely termination of medulla NBs. Medulla NBs terminate neurogenesis via a combination of apoptosis, terminal symmetric division via Prospero, and a switch to gliogenesis via Glial Cell Missing (Gcm); however, these processes occur independently of each other. We also show that temporal progression of the medulla NBs is mostly not required for their termination. As the Drosophila OL shares a similar mode of division with mammalian neurogenesis, understanding when and how these progenitors cease proliferation during development can have important implications for mammalian brain size determination and regulation of its overall function.
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Affiliation(s)
- Phuong-Khanh Nguyen
- Peter MacCallum Cancer CentreMelbourneAustralia
- Department of Anatomy and Physiology, The University of MelbourneMelbourneAustralia
| | - Louise Y Cheng
- Peter MacCallum Cancer CentreMelbourneAustralia
- Department of Anatomy and Physiology, The University of MelbourneMelbourneAustralia
- Sir Peter MacCallum Department of Oncology, The University of MelbourneMelbourneAustralia
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3
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Oliveira AC, Homem CCF. Opposing effects of ecdysone signaling regulate neuroblast proliferation to ensure coordination of brain and organism development. Dev Biol 2023; 503:53-67. [PMID: 37549863 DOI: 10.1016/j.ydbio.2023.08.001] [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: 01/13/2023] [Revised: 08/01/2023] [Accepted: 08/04/2023] [Indexed: 08/09/2023]
Abstract
Growth regulation must be robust to ensure correct final size, but also adaptative to adjust to less favorable environmental conditions. Developmental coordination between whole-organism and the brain is particularly important, as the brain is a critical organ with little adaptability. Brain growth mainly depends on neural stem cell (NSC) proliferation to generate differentiated neural cells, it is however unclear how organism developmental progression is coordinated with NSCs. Here we demonstrate that the steroid hormone ecdysone plays a multi-step, stage specific role in regulating Drosophila NSCs, the neuroblasts. We used animals that are unable to synthesize ecdysone, to show that the developmental milestone called "critical weight peak", the peak that informs the body has reached minimum viable weight to survive metamorphosis, acts a checkpoint necessary to set neuroblast cell cycle pace during larval neurogenesis. The peaks of ecdysone that occur post-critical weight are no longer required to maintain neuroblast division rate. We additionally show that in a second stage, at the onset of pupariation, ecdysone is instead required to trigger neuroblast's proliferation exit and consequently the end of neurogenesis. We demonstrate that, without this signal from ecdysone, neuroblasts lose their ability to exit proliferation. Interestingly, although these neuroblasts proliferate for a longer period, the number of differentiated neurons is smaller compared to wild-type brains, suggesting a role for ecdysone in neuron maintenance. Our study provides insights into how neural stem cells coordinate their division rate with the pace of body growth, identifying a novel coordination mechanism between animal development and NSC proliferation.
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Affiliation(s)
- Andreia C Oliveira
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, NMS, FCM, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Catarina C F Homem
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, NMS, FCM, Universidade Nova de Lisboa, Lisboa, Portugal.
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4
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Li Y, Xu B, Jin M, Zhang H, Ren N, Hu J, He J. Homophilic interaction of cell adhesion molecule 3 coordinates retina neuroepithelial cell proliferation. J Cell Biol 2023; 222:e202204098. [PMID: 37022761 PMCID: PMC10082328 DOI: 10.1083/jcb.202204098] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 01/07/2023] [Accepted: 03/07/2023] [Indexed: 04/07/2023] Open
Abstract
Correct cell number generation is central to tissue development. However, in vivo roles of coordinated proliferation of individual neural progenitors in regulating cell numbers of developing neural tissues and the underlying molecular mechanism remain mostly elusive. Here, we showed that wild-type (WT) donor retinal progenitor cells (RPCs) generated significantly expanded clones in host retinae with G1-lengthening by p15 (cdkn2a/b) overexpression (p15+) in zebrafish. Further analysis showed that cell adhesion molecule 3 (cadm3) was reduced in p15+ host retinae, and overexpression of either full-length or ectodomains of Cadm3 in p15+ host retinae markedly suppressed the clonal expansion of WT donor RPCs. Notably, WT donor RPCs in retinae with cadm3 disruption recapitulated expanded clones that were found in p15+ retinae. More strikingly, overexpression of Cadm3 without extracellular ig1 domain in RPCs resulted in expanded clones and increased retinal total cell number. Thus, homophilic interaction of Cadm3 provides an intercellular mechanism underlying coordinated cell proliferation to ensure cell number homeostasis of the developing neuroepithelia.
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Affiliation(s)
- Yanan Li
- State Key Laboratory of Neuroscience, Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Baijie Xu
- State Key Laboratory of Neuroscience, Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Mengmeng Jin
- State Key Laboratory of Neuroscience, Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hui Zhang
- State Key Laboratory of Neuroscience, Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ningxin Ren
- State Key Laboratory of Neuroscience, Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Jinhui Hu
- State Key Laboratory of Neuroscience, Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Jie He
- State Key Laboratory of Neuroscience, Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
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Hamid A, Gutierrez A, Munroe J, Syed MH. The Drivers of Diversity: Integrated genetic and hormonal cues regulate neural diversity. Semin Cell Dev Biol 2023; 142:23-35. [PMID: 35915026 DOI: 10.1016/j.semcdb.2022.07.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 07/06/2022] [Accepted: 07/17/2022] [Indexed: 11/17/2022]
Abstract
Proper functioning of the nervous system relies not only on the generation of a vast repertoire of distinct neural cell types but also on the precise neural circuitry within them. How the generation of highly diverse neural populations is regulated during development remains a topic of interest. Landmark studies in Drosophila have identified the genetic and temporal cues regulating neural diversity and thus have provided valuable insights into our understanding of temporal patterning of the central nervous system. The development of the Drosophila central complex, which is mostly derived from type II neural stem cell (NSC) lineages, showcases how a small pool of NSCs can give rise to vast and distinct progeny. Similar to the human outer subventricular zone (OSVZ) neural progenitors, type II NSCs generate intermediate neural progenitors (INPs) to expand and diversify lineages that populate higher brain centers. Each type II NSC has a distinct spatial identity and timely regulated expression of many transcription factors and mRNA binding proteins. Additionally, INPs derived from them show differential expression of genes depending on their birth order. Together type II NSCs and INPs display a combinatorial temporal patterning that expands neural diversity of the central brain lineages. We cover advances in current understanding of type II NSC temporal patterning and discuss similarities and differences in temporal patterning mechanisms of various NSCs with a focus on how cell-intrinsic and extrinsic hormonal cues regulate temporal transitions in NSCs during larval development. Cell extrinsic ligands activate conserved signaling pathways and extrinsic hormonal cues act as a temporal switch that regulate temporal progression of the NSCs. We conclude by elaborating on how a progenitor's temporal code regulates the fate specification and identity of distinct neural types. At the end, we also discuss open questions in linking developmental cues to neural identity, circuits, and underlying behaviors in the adult fly.
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Affiliation(s)
- Aisha Hamid
- Department of Biology, University of New Mexico, Albuquerque, NM 87113, USA
| | - Andrew Gutierrez
- Department of Biology, University of New Mexico, Albuquerque, NM 87113, USA
| | - Jordan Munroe
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
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6
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Truman JW, Riddiford LM. Drosophila postembryonic nervous system development: a model for the endocrine control of development. Genetics 2023; 223:iyac184. [PMID: 36645270 PMCID: PMC9991519 DOI: 10.1093/genetics/iyac184] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 12/13/2022] [Indexed: 01/17/2023] Open
Abstract
During postembryonic life, hormones, including ecdysteroids, juvenile hormones, insulin-like peptides, and activin/TGFβ ligands act to transform the larval nervous system into an adult version, which is a fine-grained mosaic of recycled larval neurons and adult-specific neurons. Hormones provide both instructional signals that make cells competent to undergo developmental change and timing cues to evoke these changes across the nervous system. While touching on all the above hormones, our emphasis is on the ecdysteroids, ecdysone and 20-hydroxyecdysone (20E). These are the prime movers of insect molting and metamorphosis and are involved in all phases of nervous system development, including neurogenesis, pruning, arbor outgrowth, and cell death. Ecdysteroids appear as a series of steroid peaks that coordinate the larval molts and the different phases of metamorphosis. Each peak directs a stereotyped cascade of transcription factor expression. The cascade components then direct temporal programs of effector gene expression, but the latter vary markedly according to tissue and life stage. The neurons read the ecdysteroid titer through various isoforms of the ecdysone receptor, a nuclear hormone receptor. For example, at metamorphosis the pruning of larval neurons is mediated through the B isoforms, which have strong activation functions, whereas subsequent outgrowth is mediated through the A isoform through which ecdysteroids play a permissive role to allow local tissue interactions to direct outgrowth. The major circulating ecdysteroid can also change through development. During adult development ecdysone promotes early adult patterning and differentiation while its metabolite, 20E, later evokes terminal adult differentiation.
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Affiliation(s)
- James W Truman
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195, USA
| | - Lynn M Riddiford
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195, USA
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7
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Egger B. Neural Stem Cells and Brain Tumour Models in Drosophila. Neurogenetics 2023. [DOI: 10.1007/978-3-031-07793-7_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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8
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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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9
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Barrett M, Godfrey RK, Sterner EJ, Waddell EA. Impacts of development and adult sex on brain cell numbers in the Black Soldier Fly, Hermetia illucens L. (Diptera: Stratiomyidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2022; 70:101174. [PMID: 35809527 DOI: 10.1016/j.asd.2022.101174] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 04/28/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
The Black Soldier Fly (Hermetia illucens, Diptera: Stratiomyidae) has been introduced across the globe, with numerous industry applications predicated on its tremendous growth during the larval stage. However, basic research on H. illucens biology (for example, studies of their central nervous system) are lacking. Despite their small brain volumes, insects are capable of complex behaviors; understanding how these behaviors are completed with such a small amount of neural tissue requires understanding processing power (e.g. number of cells) within the brain. Brain cell counts have been completed in only a few insect species (mostly Hymenoptera), and almost exclusively in adults. This limits the taxonomic breadth of comparative analyses, as well as any conclusions about how development and body size growth may impact brain cell populations. Here, we present the first images and cell counts of the H. illucens brain at four time points across development (early, mid, and late larval stages, and both male and female adults) using immunohistochemistry and isotropic fractionation. To assess sexual dimorphism in adults, we quantified the number of cells in the central brain vs. optic lobes of males and females separately. To assess if increases in body size during development might independently affect different regions of the CNS, we quantified the larval ventral nerve cord and central brain separately at all three stages. Together, these data provide the first description of the nervous system of a popular, farmed invertebrate and the first study of brain cell numbers using IF across developmental stages in any insect.
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Affiliation(s)
- Meghan Barrett
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA, 19104, USA.
| | - R Keating Godfrey
- Department of Neuroscience, University of Arizona, 1200 E. University Blvd, Tucson, AZ, 85721, USA
| | - Emily J Sterner
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA, 19104, USA
| | - Edward A Waddell
- Department of Biology, Holy Family University, 9801 Frankford Ave, Philadelphia, PA, 19114, USA
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10
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Puca F, Fedele M, Rasio D, Battista S. Role of Diet in Stem and Cancer Stem Cells. Int J Mol Sci 2022; 23:ijms23158108. [PMID: 35897685 PMCID: PMC9330301 DOI: 10.3390/ijms23158108] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 11/16/2022] Open
Abstract
Diet and lifestyle factors greatly affect health and susceptibility to diseases, including cancer. Stem cells’ functions, including their ability to divide asymmetrically, set the rules for tissue homeostasis, contribute to health maintenance, and represent the entry point of cancer occurrence. Stem cell properties result from the complex integration of intrinsic, extrinsic, and systemic factors. In this context, diet-induced metabolic changes can have a profound impact on stem cell fate determination, lineage specification and differentiation. The purpose of this review is to provide a comprehensive description of the multiple “non-metabolic” effects of diet on stem cell functions, including little-known effects such as those on liquid-liquid phase separation and on non-random chromosome segregation (asymmetric division). A deep understanding of the specific dietetic requirements of normal and cancer stem cells may pave the way for the development of nutrition-based targeted therapeutic approaches to improve regenerative and anticancer therapies.
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Affiliation(s)
- Francesca Puca
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 78705, USA;
- Department of Oncology, IRBM Science Park SpA, 00071 Pomezia, Italy
| | - Monica Fedele
- Institute for Experimental Endocrinology and Oncology (IEOS), National Research Council (CNR), 80131 Naples, Italy;
| | - Debora Rasio
- Department of Clinical and Molecular Medicine, La Sapienza University, 00185 Rome, Italy;
| | - Sabrina Battista
- Institute for Experimental Endocrinology and Oncology (IEOS), National Research Council (CNR), 80131 Naples, Italy;
- Correspondence:
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11
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Nguyen PK, Cheng LY. Non-autonomous regulation of neurogenesis by extrinsic cues: a Drosophila perspective. OXFORD OPEN NEUROSCIENCE 2022; 1:kvac004. [PMID: 38596708 PMCID: PMC10913833 DOI: 10.1093/oons/kvac004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/20/2022] [Accepted: 03/23/2022] [Indexed: 04/11/2024]
Abstract
The formation of a functional circuitry in the central nervous system (CNS) requires the correct number and subtypes of neural cells. In the developing brain, neural stem cells (NSCs) self-renew while giving rise to progenitors that in turn generate differentiated progeny. As such, the size and the diversity of cells that make up the functional CNS depend on the proliferative properties of NSCs. In the fruit fly Drosophila, where the process of neurogenesis has been extensively investigated, extrinsic factors such as the microenvironment of NSCs, nutrients, oxygen levels and systemic signals have been identified as regulators of NSC proliferation. Here, we review decades of work that explores how extrinsic signals non-autonomously regulate key NSC characteristics such as quiescence, proliferation and termination in the fly.
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Affiliation(s)
- Phuong-Khanh Nguyen
- Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- Department of Anatomy and Physiology, The University of Melbourne, Victoria 3010, Australia
| | - Louise Y Cheng
- Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Victoria 3010, Australia
- Department of Anatomy and Physiology, The University of Melbourne, Victoria 3010, Australia
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12
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Abstract
Notch signalling is a well-conserved signalling pathway that regulates cell fate through cell-cell communication. A typical feature of Notch signalling is ‘lateral inhibition’, whereby two neighbouring cells of equivalent state of differentiation acquire different cell fates. Recently, mathematical and computational approaches have addressed the Notch dynamics in Drosophila neural development. Typical examples of lateral inhibition are observed in the specification of neural stem cells in the embryo and sensory organ precursors in the thorax. In eye disc development, Notch signalling cooperates with other signalling pathways to define the evenly spaced positioning of the photoreceptor cells. The interplay between Notch and epidermal growth factor receptor signalling regulates the timing of neural stem cell differentiation in the optic lobe. In this review, we summarize the theoretical studies that have been conducted to elucidate the Notch dynamics in these systems and discuss the advantages of combining mathematical models with biological experiments.
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Affiliation(s)
- Tetsuo Yasugi
- Mathematical Neuroscience Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Makoto Sato
- Mathematical Neuroscience Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa, Japan.,Laboratory of Developmental Neurobiology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan
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13
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The Serine Protease Homolog, Scarface, Is Sensitive to Nutrient Availability and Modulates the Development of the Drosophila Blood-Brain Barrier. J Neurosci 2021; 41:6430-6448. [PMID: 34210781 PMCID: PMC8318086 DOI: 10.1523/jneurosci.0452-20.2021] [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: 03/01/2020] [Revised: 02/08/2021] [Accepted: 03/14/2021] [Indexed: 01/21/2023] Open
Abstract
The adaptable transcriptional response to changes in food availability not only ensures animal survival but also lets embryonic development progress. Interestingly, the CNS is preferentially protected from periods of malnutrition, a phenomenon known as “brain sparing.” However, the mechanisms that mediate this response remain poorly understood. To get a better understanding of this, we used Drosophila melanogaster as a model, analyzing the transcriptional response of neural stem cells (neuroblasts) and glia of the blood–brain barrier (BBB) from larvae of both sexes during nutrient restriction using targeted DamID. We found differentially expressed genes in both neuroblasts and glia of the BBB, although the effect of nutrient deficiency was primarily observed in the BBB. We characterized the function of a nutritional sensitive gene expressed in the BBB, the serine protease homolog, scarface (scaf). Scaf is expressed in subperineurial glia in the BBB in response to nutrition. Tissue-specific knockdown of scaf increases subperineurial glia endoreplication and proliferation of perineurial glia in the blood–brain barrier. Furthermore, neuroblast proliferation is diminished on scaf knockdown in subperineurial glia. Interestingly, reexpression of Scaf in subperineurial glia is able to enhance neuroblast proliferation and brain growth of animals in starvation. Finally, we show that loss of scaf in the blood–brain barrier increases sensitivity to drugs in adulthood, suggesting a physiological impairment. We propose that Scaf integrates the nutrient status to modulate the balance between neurogenesis and growth of the BBB, preserving the proper equilibrium between the size of the barrier and the brain. SIGNIFICANCE STATEMENT The Drosophila BBB separates the CNS from the open circulatory system. The BBB glia are not only acting as a physical segregation of tissues but participate in the regulation of the metabolism and neurogenesis during development. Here we analyze the transcriptional response of the BBB glia to nutrient deprivation during larval development, a condition in which protective mechanisms are switched on in the brain. Our findings show that the gene scarface reduces growth in the BBB while promoting the proliferation of neural stem, assuring the balanced growth of the larval brain. Thus, Scarface would link animal nutrition with brain development, coordinating neurogenesis with the growth of the BBB.
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14
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Oliveira AC, Rebelo AR, Homem CCF. Integrating animal development: How hormones and metabolism regulate developmental transitions and brain formation. Dev Biol 2021; 475:256-264. [PMID: 33549549 PMCID: PMC7617117 DOI: 10.1016/j.ydbio.2021.01.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 01/15/2021] [Accepted: 01/29/2021] [Indexed: 10/22/2022]
Abstract
Our current knowledge on how individual tissues or organs are formed during animal development is considerable. However, the development of each organ does not occur in isolation and thus their formation needs to be done in a coordinated manner. This coordination is regulated by hormones, systemic signals that instruct the simultaneous development of all organs and direct tissue specific developmental programs. In addition, multi- and individual-organ development requires the integration of the nutritional state of the animal, since this affects nutrient availability necessary for the progression of development and growth. Variations in the nutritional state of the animal are normal during development, as the sources and access to nutrients greatly differ depending on the animal stage. Furthermore, adversities of the external environment also exert major alterations in extrinsic nutritional conditions. Thus, both in normal and malnutrition circumstances, the animal needs to trigger metabolic changes to maintain energy homeostasis and sustain growth and development. This metabolic flexibility is mediated by hormones, that drive both developmental encoded metabolic transitions throughout development and adaptation responses according to the nutritional state of the animal. This review aims to provide a comprehensive summary of the current knowledge of how endocrine regulation coordinates multi-organ development by orchestrating metabolic transitions and how it integrates metabolic adaptation responses to starvation. We also focus on the particular case of brain development, as it is extremely sensitive to hormonally induced metabolic changes. Finally, we discuss how brain development is prioritized over the development of other organs, as its growth can be spared from nutrient deprivation.
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Affiliation(s)
- Andreia C Oliveira
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, 1169-056, Lisboa, Portugal
| | - Ana R Rebelo
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, 1169-056, Lisboa, Portugal
| | - Catarina C F Homem
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, 1169-056, Lisboa, Portugal.
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15
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Gillette CM, Tennessen JM, Reis T. Balancing energy expenditure and storage with growth and biosynthesis during Drosophila development. Dev Biol 2021; 475:234-244. [DOI: 10.1016/j.ydbio.2021.01.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 01/20/2021] [Accepted: 01/29/2021] [Indexed: 12/15/2022]
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16
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Kannangara JR, Mirth CK, Warr CG. Regulation of ecdysone production in Drosophila by neuropeptides and peptide hormones. Open Biol 2021; 11:200373. [PMID: 33593157 PMCID: PMC8103234 DOI: 10.1098/rsob.200373] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 01/26/2021] [Indexed: 12/13/2022] Open
Abstract
In both mammals and insects, steroid hormones play a major role in directing the animal's progression through developmental stages. To maximize fitness outcomes, steroid hormone production is regulated by the environmental conditions experienced by the animal. In insects, the steroid hormone ecdysone mediates transitions between developmental stages and is regulated in response to environmental factors such as nutrition. These environmental signals are communicated to the ecdysone-producing gland via the action of neuropeptide and peptide hormone signalling pathways. While some of these pathways have been well characterized, there is evidence to suggest more signalling pathways than has previously been thought function to control ecdysone production, potentially in response to a greater range of environmental conditions. Here, we review the neuropeptide and peptide hormone signalling pathways known to regulate the production of ecdysone in the model genetic insect Drosophila melanogaster, as well as what is known regarding the environmental signals that trigger these pathways. Areas for future research are highlighted that can further contribute to our overall understanding of the complex orchestration of environmental, physiological and developmental cues that together produce a functioning adult organism.
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Affiliation(s)
- Jade R. Kannangara
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Christen K. Mirth
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Coral G. Warr
- Tasmanian School of Medicine, University of Tasmania, Hobart, Tasmania 7000, Australia
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17
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Abstract
Abstract
Background
Organisms show an incredibly diverse array of body and organ shapes that are both unique to their taxon and important for adapting to their environment. Achieving these specific shapes involves coordinating the many processes that transform single cells into complex organs, and regulating their growth so that they can function within a fully-formed body.
Main text
Conceptually, body and organ shape can be separated in two categories, although in practice these categories need not be mutually exclusive. Body shape results from the extent to which organs, or parts of organs, grow relative to each other. The patterns of relative organ size are characterized using allometry. Organ shape, on the other hand, is defined as the geometric features of an organ’s component parts excluding its size. Characterization of organ shape is frequently described by the relative position of homologous features, known as landmarks, distributed throughout the organ. These descriptions fall into the domain of geometric morphometrics.
Conclusion
In this review, we discuss the methods of characterizing body and organ shape, the developmental programs thought to underlie each, highlight when and how the mechanisms regulating body and organ shape might overlap, and provide our perspective on future avenues of research.
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18
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A continuation method for spatially discretized models with nonlocal interactions conserving size and shape of cells and lattices. J Math Biol 2020; 81:981-1028. [PMID: 32959067 PMCID: PMC7560951 DOI: 10.1007/s00285-020-01534-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 07/15/2020] [Indexed: 11/18/2022]
Abstract
In this paper, we introduce a continuation method for the spatially discretized models, while conserving the size and shape of the cells and lattices. This proposed method is realized using the shift operators and nonlocal operators of convolution types. Through this method and using the shift operator, the nonlinear spatially discretized model on the uniform and nonuniform lattices can be systematically converted into a spatially continuous model; this renders both models point-wisely equivalent. Moreover, by the convolution with suitable kernels, we mollify the shift operator and approximate the spatially discretized models using the nonlocal evolution equations, rendering suitable for the application in both experimental and mathematical analyses. We also demonstrate that this approximation is supported by the singular limit analysis, and that the information of the lattice and cells is expressed in the shift and nonlocal operators. The continuous models designed using our method can successfully replicate the patterns corresponding to those of the original spatially discretized models obtained from the numerical simulations. Furthermore, from the observations of the isotropy of the Delta–Notch signaling system in a developing real fly brain, we propose a radially symmetric kernel for averaging the cell shape using our continuation method. We also apply our method for cell division and proliferation to spatially discretized models of the differentiation wave and describe the discrete models on the sphere surface. Finally, we demonstrate an application of our method in the linear stability analysis of the planar cell polarity model.
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19
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Mira H, Morante J. Neurogenesis From Embryo to Adult - Lessons From Flies and Mice. Front Cell Dev Biol 2020; 8:533. [PMID: 32695783 PMCID: PMC7339912 DOI: 10.3389/fcell.2020.00533] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/08/2020] [Indexed: 12/30/2022] Open
Abstract
The human brain is composed of billions of cells, including neurons and glia, with an undetermined number of subtypes. During the embryonic and early postnatal stages, the vast majority of these cells are generated from neural progenitors and stem cells located in all regions of the neural tube. A smaller number of neurons will continue to be generated throughout our lives, in localized neurogenic zones, mainly confined at least in rodents to the subependymal zone of the lateral ventricles and the subgranular zone of the hippocampal dentate gyrus. During neurogenesis, a combination of extrinsic cues interacting with temporal and regional intrinsic programs are thought to be critical for increasing neuronal diversity, but their underlying mechanisms need further elucidation. In this review, we discuss the recent findings in Drosophila and mammals on the types of cell division and cell interactions used by neural progenitors and stem cells to sustain neurogenesis, and how they are influenced by glia.
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Affiliation(s)
- Helena Mira
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Javier Morante
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas y Universidad Miguel Hernandez, Alicante, Spain
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20
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Zeng J, Huynh N, Phelps B, King-Jones K. Snail synchronizes endocycling in a TOR-dependent manner to coordinate entry and escape from endoreplication pausing during the Drosophila critical weight checkpoint. PLoS Biol 2020; 18:e3000609. [PMID: 32097403 PMCID: PMC7041797 DOI: 10.1371/journal.pbio.3000609] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 01/28/2020] [Indexed: 12/30/2022] Open
Abstract
The final body size of any given individual underlies both genetic and environmental constraints. Both mammals and insects use target of rapamycin (TOR) and insulin signaling pathways to coordinate growth with nutrition. In holometabolous insects, the growth period is terminated through a cascade of peptide and steroid hormones that end larval feeding behavior and trigger metamorphosis, a nonfeeding stage during which the larval body plan is remodeled to produce an adult. This irreversible decision, termed the critical weight (CW) checkpoint, ensures that larvae have acquired sufficient nutrients to complete and survive development to adulthood. How insects assess body size via the CW checkpoint is still poorly understood on the molecular level. We show here that the Drosophila transcription factor Snail plays a key role in this process. Before and during the CW checkpoint, snail is highly expressed in the larval prothoracic gland (PG), an endocrine tissue undergoing endoreplication and primarily dedicated to the production of the steroid hormone ecdysone. We observed two Snail peaks in the PG, one before and one after the molt from the second to the third instar. Remarkably, these Snail peaks coincide with two peaks of PG cells entering S phase and a slowing of DNA synthesis between the peaks. Interestingly, the second Snail peak occurs at the exit of the CW checkpoint. Snail levels then decline continuously, and endoreplication becomes nonsynchronized in the PG after the CW checkpoint. This suggests that the synchronization of PG cells into S phase via Snail represents the mechanistic link used to terminate the CW checkpoint. Indeed, PG-specific loss of snail function prior to the CW checkpoint causes larval arrest due to a cessation of endoreplication in PG cells, whereas impairing snail after the CW checkpoint no longer affected endoreplication and further development. During the CW window, starvation or loss of TOR signaling disrupted the formation of Snail peaks and endocycle synchronization, whereas later starvation had no effect on snail expression. Taken together, our data demonstrate that insects use the TOR pathway to assess nutrient status during larval development to regulate Snail in ecdysone-producing cells as an effector protein to coordinate endoreplication and CW attainment. During Drosophila development, the time window when larvae assess their readiness for metamorphosis is marked by slowing of cell growth in the prothoracic gland that produces the molting hormone; cell growth (via DNA endoreplication) then increases, allowing the production of the amount of hormone required to trigger metamorphosis. This study shows that these processes depend on the transcription factor Snail.
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Affiliation(s)
- Jie Zeng
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Nhan Huynh
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Brian Phelps
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Kirst King-Jones
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
- * E-mail:
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21
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Okamoto N, Yamanaka N. Steroid Hormone Entry into the Brain Requires a Membrane Transporter in Drosophila. Curr Biol 2020; 30:359-366.e3. [PMID: 31928869 DOI: 10.1016/j.cub.2019.11.085] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/14/2019] [Accepted: 11/28/2019] [Indexed: 02/08/2023]
Abstract
Steroid hormones control various aspects of brain development and behavior in metazoans, but how they enter the central nervous system (CNS) through the blood-brain barrier (BBB) remains poorly understood. It is generally believed that steroid hormones freely diffuse through the plasma membrane of the BBB cells to reach the brain [1], because of the predominant "simple diffusion" model of steroid hormone transport across cell membranes. Recently, however, we challenged the simple diffusion model by showing that a Drosophila organic anion-transporting polypeptide (OATP), which we named Ecdysone Importer (EcI), is required for cellular uptake of the primary insect steroid hormone ecdysone [2]. As ecdysone is first secreted into the hemolymph before reaching the CNS [3], our finding raised the question of how ecdysone enters the CNS through the BBB to exert its diverse role in Drosophila brain development. Here, we demonstrate in the Drosophila BBB that EcI is indispensable for ecdysone entry into the CNS to facilitate brain development. EcI is highly expressed in surface glial cells that form the BBB, and EcI knockdown in the BBB suppresses ecdysone signaling within the CNS and blocks ecdysone-mediated neuronal events during development. In an ex vivo culture system, the CNS requires EcI in the BBB to incorporate ecdysone from the culture medium. Our results suggest a transporter-mediated mechanism of steroid hormone entry into the CNS, which may provide important implications in controlling brain development and behavior by regulating steroid hormone permeability across the BBB.
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Affiliation(s)
- Naoki Okamoto
- Department of Entomology, Institute for Integrative Genome Biology, University of California, Riverside, 900 University Ave., Riverside, CA 92521, USA
| | - Naoki Yamanaka
- Department of Entomology, Institute for Integrative Genome Biology, University of California, Riverside, 900 University Ave., Riverside, CA 92521, USA.
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22
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Galagovsky D, Depetris-Chauvin A, Manière G, Geillon F, Berthelot-Grosjean M, Noirot E, Alves G, Grosjean Y. Sobremesa L-type Amino Acid Transporter Expressed in Glia Is Essential for Proper Timing of Development and Brain Growth. Cell Rep 2019; 24:3156-3166.e4. [PMID: 30231999 PMCID: PMC6167638 DOI: 10.1016/j.celrep.2018.08.067] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 07/13/2018] [Accepted: 08/22/2018] [Indexed: 02/07/2023] Open
Abstract
In Drosophila, ecdysone hormone levels determine the timing of larval development. Its production is regulated by the stereotypical rise in prothoracicotropic hormone (PTTH) levels. Additionally, ecdysone levels can also be modulated by nutrition (specifically by amino acids) through their action on Drosophila insulin-like peptides (Dilps). Moreover, in glia, amino-acid-sensitive production of Dilps regulates brain development. In this work, we describe the function of an SLC7 amino acid transporter, Sobremesa (Sbm). Larvae with reduced Sbm levels in glia remain in third instar for an additional 24 hr. These larvae show reduced brain growth with increased body size but do not show reduction in insulin signaling or production. Interestingly, Sbm downregulation in glia leads to reduced Ecdysone production and a surprising delay in the rise of PTTH levels. Our work highlights Sbm as a modulator of both brain development and the timing of larval development via an amino-acid-sensitive and Dilp-independent function of glia. Glia express the SLC7 amino acid transporter Sobremesa, which controls development Sobremesa downregulation in glia leads to contrasting effects: small brain and big body size Sobremesa downregulation results in reduced ecdysone production Sobremesa downregulation causes a delayed rise in PTTH
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Affiliation(s)
- Diego Galagovsky
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 21000 Dijon, France
| | - Ana Depetris-Chauvin
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 21000 Dijon, France; Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany
| | - Gérard Manière
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 21000 Dijon, France
| | - Flore Geillon
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 21000 Dijon, France
| | - Martine Berthelot-Grosjean
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 21000 Dijon, France
| | - Elodie Noirot
- Plateforme DImaCell, INRA, Université Bourgogne Franche-Comté, 21000 Dijon, France
| | - Georges Alves
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 21000 Dijon, France
| | - Yael Grosjean
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 21000 Dijon, France.
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23
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Zhou Y, Yang Y, Huang Y, Wang H, Wang S, Luo H. Broad Promotes Neuroepithelial Stem Cell Differentiation in the Drosophila Optic Lobe. Genetics 2019; 213:941-951. [PMID: 31530575 PMCID: PMC6827381 DOI: 10.1534/genetics.119.302421] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 09/08/2019] [Indexed: 11/18/2022] Open
Abstract
Brain development requires the generation of the right number, and type, of neurons and glial cells at the right time. The Drosophila optic lobe, like mammalian brains, develops from simple neuroepithelia; they first divide symmetrically to expand the progenitor pool and then differentiate into neuroblasts, which divide asymmetrically to generate neurons and glial cells. Here, we investigate the mechanisms that control neuroepithelial growth and differentiation in the optic lobe. We find that the Broad/Tramtrack/Bric a brac-zinc finger protein Broad, which is dynamically expressed in the optic lobe neuroepithelia, promotes the transition of neuroepithelial cells to medulla neuroblasts. Loss of Broad function causes neuroepithelial cells to remain highly proliferative and delays neuroepithelial cell differentiation into neuroblasts, which leads to defective lamina and medulla. Conversely, Broad overexpression induces neuroepithelial cells to prematurely transform into medulla neuroblasts. We find that the ecdysone receptor is required for neuroepithelial maintenance and growth, and that Broad expression in neuroepithelial cells is repressed by the ecdysone receptor. Our studies identify Broad as an important cell-intrinsic transcription factor that promotes the neuroepithelial-cell-to-neuroblast transition.
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Affiliation(s)
- Yanna Zhou
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yuqin Yang
- College of Biology, Hunan University, Changsha, Hunan 410082, China
| | - Yanyi Huang
- College of Biology, Hunan University, Changsha, Hunan 410082, China
| | - Hui Wang
- College of Biology, Hunan University, Changsha, Hunan 410082, China
| | - Shengyu Wang
- College of Biology, Hunan University, Changsha, Hunan 410082, China
| | - Hong Luo
- School of Life Sciences, Tsinghua University, Beijing 100084, China
- College of Biology, Hunan University, Changsha, Hunan 410082, China
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24
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McKeown CR, Cline HT. Nutrient restriction causes reversible G2 arrest in Xenopus neural progenitors. Development 2019; 146:146/20/dev178871. [PMID: 31649012 DOI: 10.1242/dev.178871] [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: 04/02/2019] [Accepted: 09/05/2019] [Indexed: 01/23/2023]
Abstract
Nutrient status affects brain development; however, the effects of nutrient availability on neural progenitor cell proliferation in vivo are poorly understood. Without food, Xenopus laevis tadpoles enter a period of stasis during which neural progenitor proliferation is drastically reduced, but resumes when food becomes available. Here, we investigate how neural progenitors halt cell division in response to nutrient restriction and subsequently re-enter the cell cycle upon feeding. We demonstrate that nutrient restriction causes neural progenitors to arrest in G2 of the cell cycle with increased DNA content, and that nutrient availability triggers progenitors to re-enter the cell cycle at M phase. Initiation of the nutrient restriction-induced G2 arrest is rapamycin insensitive, but cell cycle re-entry requires mTOR. Finally, we show that activation of insulin receptor signaling is sufficient to increase neural progenitor cell proliferation in the absence of food. A G2 arrest mechanism provides an adaptive strategy to control brain development in response to nutrient availability by triggering a synchronous burst of cell proliferation when nutrients become available. This may be a general cellular mechanism that allows developmental flexibility during times of limited resources.
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Affiliation(s)
| | - Hollis T Cline
- Department of Neuroscience, Scripps Research, La Jolla, CA 92037, USA
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25
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Contreras EG, Sierralta J, Oliva C. Novel Strategies for the Generation of Neuronal Diversity: Lessons From the Fly Visual System. Front Mol Neurosci 2019; 12:140. [PMID: 31213980 PMCID: PMC6554424 DOI: 10.3389/fnmol.2019.00140] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 05/13/2019] [Indexed: 12/17/2022] Open
Abstract
Among all organs of an adult animal, the central nervous system stands out because of its vast complexity and morphological diversity. During early development, the entire central nervous system develops from an apparently homogenous group of progenitors that differentiate into all neural cell types. Therefore, understanding the molecular and genetic mechanisms that give rise to the cellular and anatomical diversity of the brain is a key goal of the developmental neurobiology field. With this aim in mind, the development of the central nervous system of model organisms has been extensively studied. From more than a century, the mechanisms of neurogenesis have been studied in the fruit fly Drosophila melanogaster. The visual system comprises one of the major structures of the Drosophila brain. The visual information is collected by the eye-retina photoreceptors and then processed by the four optic lobe ganglia: the lamina, medulla, lobula and lobula plate. The molecular mechanisms that originate neuronal diversity in the optic lobe have been unveiled in the past decade. In this article, we describe the early development and differentiation of the lobula plate ganglion, from the formation of the optic placode and the inner proliferation center to the specification of motion detection neurons. We focused specifically on how the precise combination of signaling pathways and cell-specific transcription factors patterns the pool of neural stem cells that generates the different neurons of the motion detection system.
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Affiliation(s)
- Esteban G Contreras
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Jimena Sierralta
- Department of Neuroscience and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Carlos Oliva
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
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26
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Ramon-Cañellas P, Peterson HP, Morante J. From Early to Late Neurogenesis: Neural Progenitors and the Glial Niche from a Fly's Point of View. Neuroscience 2018; 399:39-52. [PMID: 30578972 DOI: 10.1016/j.neuroscience.2018.12.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 12/06/2018] [Accepted: 12/12/2018] [Indexed: 12/15/2022]
Abstract
Drosophila melanogaster is an important model organism used to study the brain development of organisms ranging from insects to mammals. The central nervous system in fruit flies is formed primarily in two waves of neurogenesis, one of which occurs in the embryo and one of which occurs during larval stages. In order to understand neurogenesis, it is important to research the behavior of progenitor cells that give rise to the neural networks which make up the adult nervous system. This behavior has been shown to be influenced by different factors including interactions with other cells within the progenitor niche, or local tissue microenvironment. Glial cells form a crucial part of this niche and play an active role in the development of the brain. Although in the early years of neuroscience it was believed that glia were simply scaffolding for neurons and passive components of the nervous system, their importance is nowadays recognized. Recent discoveries in progenitors and niche cells have led to new understandings of how the developing brain shapes its diverse regions. In this review, we attempt to summarize the distinct neural progenitors and glia in the Drosophila melanogaster central nervous system, from embryo to late larval stages, and make note of homologous features in mammals. We also outline the recent advances in this field in order to define the impact that glial cells have on progenitor cell niches, and we finally emphasize the importance of communication between glia and progenitor cells for proper brain formation.
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Affiliation(s)
- Pol Ramon-Cañellas
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC), and Universidad Miguel Hernández (UMH), Campus de Sant Joan, Apartado 18, 03550 Sant Joan, Alicante, Spain
| | - Hannah Payette Peterson
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC), and Universidad Miguel Hernández (UMH), Campus de Sant Joan, Apartado 18, 03550 Sant Joan, Alicante, Spain
| | - Javier Morante
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC), and Universidad Miguel Hernández (UMH), Campus de Sant Joan, Apartado 18, 03550 Sant Joan, Alicante, Spain.
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27
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Contreras EG, Egger B, Gold KS, Brand AH. Dynamic Notch signalling regulates neural stem cell state progression in the Drosophila optic lobe. Neural Dev 2018; 13:25. [PMID: 30466475 PMCID: PMC6251220 DOI: 10.1186/s13064-018-0123-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/13/2018] [Indexed: 11/10/2022] Open
Abstract
Background Neural stem cells generate all of the neurons and glial cells in the central nervous system, both during development and in the adult to maintain homeostasis. In the Drosophila optic lobe, neuroepithelial cells progress through two transient progenitor states, PI and PII, before transforming into neuroblasts. Here we analyse the role of Notch signalling in the transition from neuroepithelial cells to neuroblasts. Results We observed dynamic regulation of Notch signalling: strong activity in PI progenitors, low signalling in PII progenitors, and increased activity after neuroblast transformation. Ectopic expression of the Notch ligand Delta induced the formation of ectopic PI progenitors. Interestingly, we show that the E3 ubiquitin ligase, Neuralized, regulates Delta levels and Notch signalling activity at the transition zone. We demonstrate that the proneural transcription factor, Lethal of scute, is essential to induce expression of Neuralized and promote the transition from the PI progenitor to the PII progenitor state. Conclusions Our results show dynamic regulation of Notch signalling activity in the transition from neuroepithelial cells to neuroblasts. We propose a model in which Lethal of scute activates Notch signalling in a non-cell autonomous manner by regulating the expression of Neuralized, thereby promoting the progression between different neural stem cell states. Electronic supplementary material The online version of this article (10.1186/s13064-018-0123-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Esteban G Contreras
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Boris Egger
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK.,Present Address: Department of Biology, Zoology, University of Fribourg, Chemin du Musée 10, CH-1700, Fribourg, Switzerland
| | - Katrina S Gold
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Andrea H Brand
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK.
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28
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Sato M, Yasugi T, Trush O. Temporal patterning of neurogenesis and neural wiring in the fly visual system. Neurosci Res 2018; 138:49-58. [PMID: 30227165 DOI: 10.1016/j.neures.2018.09.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 08/13/2018] [Accepted: 08/13/2018] [Indexed: 12/21/2022]
Abstract
During neural development, a wide variety of neurons are produced in a highly coordinated manner and form complex and highly coordinated neural circuits. Temporal patterning of neuron type specification plays very important roles in orchestrating the production and wiring of neurons. The fly visual system, which is composed of the retina and the optic lobe of the brain, is an outstanding model system to study temporal patterning and wiring of the nervous system. All of the components of the fly visual system are topographically connected, and each ommatidial unit in the retina corresponds to a columnar unit in the optic lobe. In the retina, the wave of differentiation follows the morphogenetic furrow, which progresses in a posterior-to-anterior direction. At the same time, differentiation of the optic lobe also accompanies the wave of differentiation or temporally coordinated neurogenesis. Thus, temporal patterning plays important roles in establishing topographic connections throughout the fly visual system. In this article, we review how neuronal differentiation and connectivity are orchestrated in the fly visual system by temporal patterning mechanisms.
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Affiliation(s)
- Makoto Sato
- Mathematical Neuroscience Unit, Institute for Frontier Science Initiative, Japan; Lab of Developmental Neurobiology, Graduate School of Medical Sciences, Kanazawa University, Japan.
| | - Tetsuo Yasugi
- Mathematical Neuroscience Unit, Institute for Frontier Science Initiative, Japan
| | - Olena Trush
- Lab of Developmental Neurobiology, Graduate School of Medical Sciences, Kanazawa University, Japan
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29
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Iung LHDS, Mulder HA, Neves HHDR, Carvalheiro R. Genomic regions underlying uniformity of yearling weight in Nellore cattle evaluated under different response variables. BMC Genomics 2018; 19:619. [PMID: 30115034 PMCID: PMC6097312 DOI: 10.1186/s12864-018-5003-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 08/08/2018] [Indexed: 02/22/2023] Open
Abstract
BACKGROUND In livestock, residual variance has been studied because of the interest to improve uniformity of production. Several studies have provided evidence that residual variance is partially under genetic control; however, few investigations have elucidated genes that control it. The aim of this study was to identify genomic regions associated with within-family residual variance of yearling weight (YW; N = 423) in Nellore bulls with high density SNP data, using different response variables. For this, solutions from double hierarchical generalized linear models (DHGLM) were used to provide the response variables, as follows: a DGHLM assuming non-null genetic correlation between mean and residual variance (rmv ≠ 0) to obtain deregressed EBV for mean (dEBVm) and residual variance (dEBVv); and a DHGLM assuming rmv = 0 to obtain two alternative response variables for residual variance, dEBVv_r0 and log-transformed variance of estimated residuals (ln_[Formula: see text]). RESULTS The dEBVm and dEBVv were highly correlated, resulting in common regions associated with mean and residual variance of YW. However, higher effects on variance than the mean showed that these regions had effects on the variance beyond scale effects. More independent association results between mean and residual variance were obtained when null rmv was assumed. While 13 and 4 single nucleotide polymorphisms (SNPs) showed a strong association (Bayes Factor > 20) with dEBVv and ln_[Formula: see text], respectively, only suggestive signals were found for dEBVv_r0. All overlapping 1-Mb windows among top 20 between dEBVm and dEBVv were previously associated with growth traits. The potential candidate genes for uniformity are involved in metabolism, stress, inflammatory and immune responses, mineralization, neuronal activity and bone formation. CONCLUSIONS It is necessary to use a strategy like assuming null rmv to obtain genomic regions associated with uniformity that are not associated with the mean. Genes involved not only in metabolism, but also stress, inflammatory and immune responses, mineralization, neuronal activity and bone formation were the most promising biological candidates for uniformity of YW. Although no clear evidence of using a specific response variable was found, we recommend consider different response variables to study uniformity to increase evidence on candidate regions and biological mechanisms behind it.
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Affiliation(s)
- Laiza Helena de Souza Iung
- School of Agricultural and Veterinarian Sciences, São Paulo State University (Unesp), Via de Acesso Prof. Paulo Donato Castelane, S/N, Vila Industrial, FCAV/UNESP, Jaboticabal, São Paulo, 14884-900 Brazil
| | - Herman Arend Mulder
- Wageningen University & Research Animal Breeding and Genomics, P.O. Box 338, 6700 AH Wageningen, The Netherlands
| | | | - Roberto Carvalheiro
- School of Agricultural and Veterinarian Sciences, São Paulo State University (Unesp), Via de Acesso Prof. Paulo Donato Castelane, S/N, Vila Industrial, FCAV/UNESP, Jaboticabal, São Paulo, 14884-900 Brazil
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30
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Caygill EE, Brand AH. miR-7 Buffers Differentiation in the Developing Drosophila Visual System. Cell Rep 2018; 20:1255-1261. [PMID: 28793250 PMCID: PMC5561169 DOI: 10.1016/j.celrep.2017.07.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 05/23/2017] [Accepted: 07/18/2017] [Indexed: 01/21/2023] Open
Abstract
The 40,000 neurons of the medulla, the largest visual processing center of the Drosophila brain, derive from a sheet of neuroepithelial cells. During larval development, a wave of differentiation sweeps across the neuroepithelium, converting neuroepithelial cells into neuroblasts that sequentially express transcription factors specifying different neuronal cell fates. The switch from neuroepithelial cells to neuroblasts is controlled by a complex gene regulatory network and is marked by the expression of the proneural gene l’sc. We discovered that microRNA miR-7 is expressed at the transition between neuroepithelial cells and neuroblasts. We showed that miR-7 promotes neuroepithelial cell-to-neuroblast transition by targeting downstream Notch effectors to limit Notch signaling. miR-7 acts as a buffer to ensure that a precise and stereotypical pattern of transition is maintained, even under conditions of environmental stress, echoing the role that miR-7 plays in the eye imaginal disc. This common mechanism reflects the importance of robust visual system development. miR-7 promotes neuroblast formation during optic lobe development miR-7 targets the Notch pathway miR-7 buffers the effects of environmental stress Without miR-7, timely neuroblast production is disrupted
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Affiliation(s)
- Elizabeth E Caygill
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Andrea H Brand
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
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31
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Dillard C, Narbonne-Reveau K, Foppolo S, Lanet E, Maurange C. Two distinct mechanisms silence chinmo in Drosophila neuroblasts and neuroepithelial cells to limit their self-renewal. Development 2018; 145:dev.154534. [PMID: 29361557 DOI: 10.1242/dev.154534] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 12/18/2017] [Indexed: 02/03/2023]
Abstract
Whether common principles regulate the self-renewing potential of neural stem cells (NSCs) throughout the developing central nervous system is still unclear. In the Drosophila ventral nerve cord and central brain, asymmetrically dividing NSCs, called neuroblasts (NBs), progress through a series of sequentially expressed transcription factors that limits self-renewal by silencing a genetic module involving the transcription factor Chinmo. Here, we find that Chinmo also promotes neuroepithelium growth in the optic lobe during early larval stages by boosting symmetric self-renewing divisions while preventing differentiation. Neuroepithelium differentiation in late larvae requires the transcriptional silencing of chinmo by ecdysone, the main steroid hormone, therefore allowing coordination of neural stem cell self-renewal with organismal growth. In contrast, chinmo silencing in NBs is post-transcriptional and does not require ecdysone. Thus, during Drosophila development, humoral cues or tissue-intrinsic temporal specification programs respectively limit self-renewal in different types of neural progenitors through the transcriptional and post-transcriptional regulation of the same transcription factor.
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Affiliation(s)
- Caroline Dillard
- Aix Marseille Univ, CNRS, IBDM, Campus de Luminy Case 907, 13288 Marseille Cedex 9, France
| | - Karine Narbonne-Reveau
- Aix Marseille Univ, CNRS, IBDM, Campus de Luminy Case 907, 13288 Marseille Cedex 9, France
| | - Sophie Foppolo
- Aix Marseille Univ, CNRS, IBDM, Campus de Luminy Case 907, 13288 Marseille Cedex 9, France
| | - Elodie Lanet
- Aix Marseille Univ, CNRS, IBDM, Campus de Luminy Case 907, 13288 Marseille Cedex 9, France
| | - Cédric Maurange
- Aix Marseille Univ, CNRS, IBDM, Campus de Luminy Case 907, 13288 Marseille Cedex 9, France
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32
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Groothuis J, Smid HM. Nasonia Parasitic Wasps Escape from Haller's Rule by Diphasic, Partially Isometric Brain-Body Size Scaling and Selective Neuropil Adaptations. BRAIN, BEHAVIOR AND EVOLUTION 2017; 90:243-254. [PMID: 29059675 DOI: 10.1159/000480421] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 08/16/2017] [Indexed: 11/19/2022]
Abstract
Haller's rule states that brains scale allometrically with body size in all animals, meaning that relative brain size increases with decreasing body size. This rule applies both on inter- and intraspecific comparisons. Only 1 species, the extremely small parasitic wasp Trichogramma evanescens, is known as an exception and shows an isometric brain-body size relation in an intraspecific comparison between differently sized individuals. Here, we investigated if such an isometric brain-body size relationship also occurs in an intraspecific comparison with a slightly larger parasitic wasp, Nasonia vitripennis, a species that may vary 10-fold in body weight upon differences in levels of scramble competition during larval development. We show that Nasonia exhibits diphasic brain-body size scaling: larger wasps scale allometrically, following Haller's rule, whereas the smallest wasps show isometric scaling. Brains of smaller wasps are, therefore, smaller than expected and we hypothesized that this may lead to adaptations in brain architecture. Volumetric analysis of neuropil composition revealed that wasps of different sizes differed in relative volume of multiple neuropils. The optic lobes and mushroom bodies in particular were smaller in the smallest wasps. Furthermore, smaller brains had a relatively smaller total neuropil volume and larger cellular rind than large brains. These changes in relative brain size and brain architecture suggest that the energetic constraints on brain tissue outweigh specific cognitive requirements in small Nasonia wasps.
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Affiliation(s)
- Jitte Groothuis
- Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
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33
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Affiliation(s)
| | - Thomas R Clandinin
- Department of Neurobiology, Stanford University, Stanford, CA 94305, USA.
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34
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Rossi AM, Fernandes VM, Desplan C. Timing temporal transitions during brain development. Curr Opin Neurobiol 2016; 42:84-92. [PMID: 27984764 DOI: 10.1016/j.conb.2016.11.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 11/24/2016] [Accepted: 11/24/2016] [Indexed: 01/05/2023]
Abstract
During development a limited number of progenitors generate diverse cell types that comprise the nervous system. Neuronal diversity, which arises largely at the level of neural stem cells, is critical for brain function. Often these cells exhibit temporal patterning: they sequentially produce neurons of distinct cell fates as a consequence of intrinsic and/or extrinsic cues. Here, we review recent advances in temporal patterning during neuronal specification, focusing on conserved players and mechanisms in invertebrate and vertebrate models. These studies underscore temporal patterning as an evolutionarily conserved strategy to generate neuronal diversity. Understanding the general principles governing temporal patterning and the molecular players involved will improve our ability to direct neural progenitors towards specific neuronal fates for brain repair.
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Affiliation(s)
- Anthony M Rossi
- Department of Biology, New York University, New York, NY 10003, USA
| | | | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA; CGSB, NYU Abu Dhabi, United Arab Emirates.
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35
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Alvarez-Rivero J, Moris-Sanz M, Estacio-Gómez A, Montoliu-Nerin M, Díaz-Benjumea FJ, Herrero P. Variability in the number of abdominal leucokinergic neurons in adult Drosophila melanogaster. J Comp Neurol 2016; 525:639-660. [PMID: 27506156 DOI: 10.1002/cne.24093] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 07/25/2016] [Accepted: 07/25/2016] [Indexed: 12/15/2022]
Abstract
Developmental plasticity allows individuals with the same genotype to show different phenotypes in response to environmental changes. An example of this is how neuronal diversity is protected at the expense of neuronal number under sustained undernourishment during the development of the Drosophila optic lobe. In the development of the Drosophila central nervous system, neuroblasts go through two phases of neurogenesis separated by a period of mitotic quiescence. Although during embryonic development much evidence indicates that both cell number and the cell fates generated by each neuroblast are very precisely controlled in a cell autonomous manner, after quiescence extrinsic factors control the reactivation of neuroblast proliferation in a fashion that has not yet been elucidated. Moreover, there is very little information about whether environmental changes affect lineage progression during postembryonic neurogenesis. Using as a model system the pattern of abdominal leucokinergic neurons (ABLKs), we have analyzed how changes in a set of environmental factors affect the number of ABLKs generated during postembryonic neurogenesis. We describe the variability in ABLK number between individuals and between hemiganglia of the same individual and, by genetic analysis, we identify the bithorax-complex genes and the ecdysone hormone as critical factors in these differences. We also explore the possible adaptive roles involved in this process. J. Comp. Neurol. 525:639-660, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Marta Moris-Sanz
- Severo Ochoa Center for Molecular Biology (CBMSO), 28049, Madrid, Spain
| | | | | | | | - Pilar Herrero
- Severo Ochoa Center for Molecular Biology (CBMSO), 28049, Madrid, Spain.,Department of Biology, Faculty of Sciences, Autonoma University of Madrid, 28049, Madrid, Spain
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36
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Cinnamon E, Makki R, Sawala A, Wickenberg LP, Blomquist GJ, Tittiger C, Paroush Z, Gould AP. Drosophila Spidey/Kar Regulates Oenocyte Growth via PI3-Kinase Signaling. PLoS Genet 2016; 12:e1006154. [PMID: 27500738 PMCID: PMC4976899 DOI: 10.1371/journal.pgen.1006154] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 06/08/2016] [Indexed: 11/19/2022] Open
Abstract
Cell growth and proliferation depend upon many different aspects of lipid metabolism. One key signaling pathway that is utilized in many different anabolic contexts involves Phosphatidylinositide 3-kinase (PI3K) and its membrane lipid products, the Phosphatidylinositol (3,4,5)-trisphosphates. It remains unclear, however, which other branches of lipid metabolism interact with the PI3K signaling pathway. Here, we focus on specialized fat metabolizing cells in Drosophila called larval oenocytes. In the presence of dietary nutrients, oenocytes undergo PI3K-dependent cell growth and contain very few lipid droplets. In contrast, during starvation, oenocytes decrease PI3K signaling, shut down cell growth and accumulate abundant lipid droplets. We now show that PI3K in larval oenocytes, but not in fat body cells, functions to suppress lipid droplet accumulation. Several enzymes of fatty acid, triglyceride and hydrocarbon metabolism are required in oenocytes primarily for lipid droplet induction rather than for cell growth. In contrast, a very long chain fatty-acyl-CoA reductase (FarO) and a putative lipid dehydrogenase/reductase (Spidey, also known as Kar) not only promote lipid droplet induction but also inhibit oenocyte growth. In the case of Spidey/Kar, we show that the growth suppression mechanism involves inhibition of the PI3K signaling pathway upstream of Akt activity. Together, the findings in this study show how Spidey/Kar and FarO regulate the balance between the cell growth and lipid storage of larval oenocytes. Lipids play diverse roles in health and disease. Some types of lipids function as metabolic fuels for energy homeostasis, whereas others act as components of cell membranes or serve as signals regulating cell behaviors. Much, however, remains to be discovered about the molecular connections between different categories of lipids. Phosphatidylinositide 3-kinase (PI3K) is an enzyme that synthesizes phosphatidylinositide lipids, which act as signals essential for growth during normal development and cancer. Using genetics in the fruit fly, Drosophila, we identify new regulatory links between phosphatidylinositides and lipid oxidoreductases in specialized fat-metabolizing cells called oenocytes. We find that an enzyme metabolizing very long chain fatty acids (VLCFAs) and also a putative lipid dehydrogenase/reductase both act to prevent the inappropriate overgrowth of oenocytes. In the case of the latter enzyme, it suppresses cell growth by inhibiting phosphatidylinositide signaling. Future studies will determine whether similar lipid enzymes regulate PI3K signaling in other cell and tissue types during normal development and tumorigenesis.
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Affiliation(s)
- Einat Cinnamon
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, United Kingdom
| | - Rami Makki
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, United Kingdom
| | - Annick Sawala
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, United Kingdom
| | - Leah P. Wickenberg
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, Nevada, United States of America
| | - Gary J. Blomquist
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, Nevada, United States of America
| | - Claus Tittiger
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, Nevada, United States of America
| | - Ze'ev Paroush
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel Canada (IMRIC), Faculty of Medicine, the Hebrew University, Jerusalem, Israel
| | - Alex P. Gould
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, United Kingdom
- * E-mail:
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37
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Faunes F, Larraín J. Conservation in the involvement of heterochronic genes and hormones during developmental transitions. Dev Biol 2016; 416:3-17. [DOI: 10.1016/j.ydbio.2016.06.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 06/03/2016] [Accepted: 06/09/2016] [Indexed: 01/26/2023]
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38
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Pinto-Teixeira F, Konstantinides N, Desplan C. Programmed cell death acts at different stages of Drosophila neurodevelopment to shape the central nervous system. FEBS Lett 2016; 590:2435-2453. [PMID: 27404003 DOI: 10.1002/1873-3468.12298] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 07/08/2016] [Accepted: 07/11/2016] [Indexed: 12/19/2022]
Abstract
Nervous system development is a process that integrates cell proliferation, differentiation, and programmed cell death (PCD). PCD is an evolutionary conserved mechanism and a fundamental developmental process by which the final cell number in a nervous system is established. In vertebrates and invertebrates, PCD can be determined intrinsically by cell lineage and age, as well as extrinsically by nutritional, metabolic, and hormonal states. Drosophila has been an instrumental model for understanding how this mechanism is regulated. We review the role of PCD in Drosophila central nervous system development from neural progenitors to neurons, its molecular mechanism and function, how it is regulated and implemented, and how it ultimately shapes the fly central nervous system from the embryo to the adult. Finally, we discuss ideas that emerged while integrating this information.
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Affiliation(s)
- Filipe Pinto-Teixeira
- Department of Biology, New York University 1009 Silver Center 100 Washington Square East, New York, NY 10003, USA.,Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi 129188, UAE
| | - Nikolaos Konstantinides
- Department of Biology, New York University 1009 Silver Center 100 Washington Square East, New York, NY 10003, USA
| | - Claude Desplan
- Department of Biology, New York University 1009 Silver Center 100 Washington Square East, New York, NY 10003, USA.,Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi 129188, UAE
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39
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Benítez-Santana T, Simion M, Corraze G, Médale F, Joly JS. Effect of Nutrient Availability on Progenitor Cells in Zebrafish (Danio Rerio). Dev Neurobiol 2016; 77:26-38. [DOI: 10.1002/dneu.22406] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 06/02/2016] [Accepted: 06/05/2016] [Indexed: 12/12/2022]
Affiliation(s)
- Tibiábin Benítez-Santana
- INRA CASBAH Group, Neuroscience Paris-Saclay Institute (Neuro-PSI) UMR 9197, CNRS - Université Paris Sud; Bat. 32/33, 1 Avenue De La Terrasse Gif-sur-Yvette 91198 France
| | - Matthieu Simion
- INRA CASBAH Group, Neuroscience Paris-Saclay Institute (Neuro-PSI) UMR 9197, CNRS - Université Paris Sud; Bat. 32/33, 1 Avenue De La Terrasse Gif-sur-Yvette 91198 France
| | - Geneviève Corraze
- INRA UR 1067, Nutrition, Metabolism, and Aquaculture; Saint Pée-sur-Nivelle France
| | - Françoise Médale
- INRA UR 1067, Nutrition, Metabolism, and Aquaculture; Saint Pée-sur-Nivelle France
| | - Jean-Stéphane Joly
- INRA CASBAH Group, Neuroscience Paris-Saclay Institute (Neuro-PSI) UMR 9197, CNRS - Université Paris Sud; Bat. 32/33, 1 Avenue De La Terrasse Gif-sur-Yvette 91198 France
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40
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Khaliullina H, Love NK, Harris WA. Nutrient-Deprived Retinal Progenitors Proliferate in Response to Hypoxia: Interaction of the HIF-1 and mTOR Pathway. J Dev Biol 2016; 4. [PMID: 27280081 PMCID: PMC4894462 DOI: 10.3390/jdb4020017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
At a cellular level, nutrients are sensed by the mechanistic Target of Rapamycin (mTOR). The response of cells to hypoxia is regulated via action of the oxygen sensor Hypoxia-Inducible Factor 1 (HIF-1). During development, injury and disease, tissues might face conditions of both low nutrient supply and low oxygen, yet it is not clear how cells adapt to both nutrient restriction and hypoxia, or how mTOR and HIF-1 interact in such conditions. Here we explore this question in vivo with respect to cell proliferation using the ciliary marginal zone (CMZ) of Xenopus. We found that both nutrient-deprivation and hypoxia cause retinal progenitors to decrease their proliferation, yet when nutrient-deprived progenitors are exposed to hypoxia there is an unexpected rise in cell proliferation. This increase, mediated by HIF-1 signalling, is dependent on glutaminolysis and reactivation of the mTOR pathway. We discuss how these findings in non-transformed tissue may also shed light on the ability of cancer cells in poorly vascularised solid tumours to proliferate.
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Affiliation(s)
- Helena Khaliullina
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK;
| | - Nicola K Love
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK;
| | - William A Harris
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK;
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41
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Mendes CC, Mirth CK. Stage-Specific Plasticity in Ovary Size Is Regulated by Insulin/Insulin-Like Growth Factor and Ecdysone Signaling in Drosophila. Genetics 2016; 202:703-19. [PMID: 26715667 PMCID: PMC4788244 DOI: 10.1534/genetics.115.179960] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 12/21/2015] [Indexed: 02/07/2023] Open
Abstract
Animals from flies to humans adjust their development in response to environmental conditions through a series of developmental checkpoints, which alter the sensitivity of organs to environmental perturbation. Despite their importance, we know little about the molecular mechanisms through which this change in sensitivity occurs. Here we identify two phases of sensitivity to larval nutrition that contribute to plasticity in ovariole number, an important determinant of fecundity, in Drosophila melanogaster. These two phases of sensitivity are separated by the developmental checkpoint called "critical weight"; poor nutrition has greater effects on ovariole number in larvae before critical weight than after. We find that this switch in sensitivity results from distinct developmental processes. In precritical weight larvae, poor nutrition delays the onset of terminal filament cell differentiation, the starting point for ovariole development, and strongly suppresses the rate of terminal filament addition and the rate of increase in ovary volume. Conversely, in postcritical weight larvae, poor nutrition affects only the rate of increase in ovary volume. Our results further indicate that two hormonal pathways, the insulin/insulin-like growth factor and the ecdysone-signaling pathways, modulate the timing and rates of all three developmental processes. The change in sensitivity in the ovary results from changes in the relative contribution of each pathway to the rates of terminal filament addition and increase in ovary volume before and after critical weight. Our work deepens our understanding of how hormones act to modify the sensitivity of organs to environmental conditions, thereby affecting their plasticity.
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Affiliation(s)
- Cláudia C Mendes
- Development, Evolution, and the Environment Laboratory, Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
| | - Christen K Mirth
- Development, Evolution, and the Environment Laboratory, Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
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42
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Bailey AP, Koster G, Guillermier C, Hirst EMA, MacRae JI, Lechene CP, Postle AD, Gould AP. Antioxidant Role for Lipid Droplets in a Stem Cell Niche of Drosophila. Cell 2016; 163:340-53. [PMID: 26451484 PMCID: PMC4601084 DOI: 10.1016/j.cell.2015.09.020] [Citation(s) in RCA: 472] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 06/15/2015] [Accepted: 08/12/2015] [Indexed: 12/19/2022]
Abstract
Stem cells reside in specialized microenvironments known as niches. During Drosophila development, glial cells provide a niche that sustains the proliferation of neural stem cells (neuroblasts) during starvation. We now find that the glial cell niche also preserves neuroblast proliferation under conditions of hypoxia and oxidative stress. Lipid droplets that form in niche glia during oxidative stress limit the levels of reactive oxygen species (ROS) and inhibit the oxidation of polyunsaturated fatty acids (PUFAs). These droplets protect glia and also neuroblasts from peroxidation chain reactions that can damage many types of macromolecules. The underlying antioxidant mechanism involves diverting PUFAs, including diet-derived linoleic acid, away from membranes to the core of lipid droplets, where they are less vulnerable to peroxidation. This study reveals an antioxidant role for lipid droplets that could be relevant in many different biological contexts. Oxidative stress stimulates lipid droplet biosynthesis in a neural stem cell niche Lipid droplets protect niche and neural stem cells from damaging PUFA peroxidation PUFAs are less vulnerable to peroxidation in lipid droplets than in cell membranes
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Affiliation(s)
- Andrew P Bailey
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Grielof Koster
- Academic Unit of Clinical & Experimental Sciences, Faculty of Medicine, Sir Henry Wellcome Laboratories, Southampton General Hospital, Southampton SO16 6YD, UK
| | - Christelle Guillermier
- National Resource for Imaging Mass Spectroscopy, Harvard Medical School and Brigham and Women's Hospital, Cambridge, MA 02139, USA
| | - Elizabeth M A Hirst
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - James I MacRae
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Claude P Lechene
- National Resource for Imaging Mass Spectroscopy, Harvard Medical School and Brigham and Women's Hospital, Cambridge, MA 02139, USA
| | - Anthony D Postle
- Academic Unit of Clinical & Experimental Sciences, Faculty of Medicine, Sir Henry Wellcome Laboratories, Southampton General Hospital, Southampton SO16 6YD, UK
| | - Alex P Gould
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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Yasugi T, Nishimura T. Temporal regulation of the generation of neuronal diversity in Drosophila. Dev Growth Differ 2015; 58:73-87. [PMID: 26690868 DOI: 10.1111/dgd.12245] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/10/2015] [Accepted: 10/10/2015] [Indexed: 12/18/2022]
Abstract
For the construction of complex neural networks, the generation of neurons and glia must be tightly regulated both spatially and temporally. One of the major issues in neural development is the generation of a large variety of neurons and glia over time from a relatively small number of neural stem cells. In Drosophila, neural stem cells, called neuroblasts (NBs), have been used as a useful model system to uncover the molecular and cellular machinery involved in the establishment of neural diversity. NBs divide asymmetrically and produce another self-renewing progenitor cell and a differentiating cell. NBs are subdivided into several types based on their location in the central nervous system. Each type of NB has specific features related to the timing of cell generation, cell cycle progression, temporal patterning for neuronal specification, and termination mechanism. In this review, we focus on the molecular mechanisms that regulate the proliferation of NBs and generate a large variety of neuronal and glia subtypes during development.
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Affiliation(s)
- Tetsuo Yasugi
- Laboratory for Growth Control Signaling, RIKEN Center for Developmental Biology (CDB), 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Takashi Nishimura
- Laboratory for Growth Control Signaling, RIKEN Center for Developmental Biology (CDB), 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
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44
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Homem CCF, Repic M, Knoblich JA. Proliferation control in neural stem and progenitor cells. Nat Rev Neurosci 2015; 16:647-59. [PMID: 26420377 DOI: 10.1038/nrn4021] [Citation(s) in RCA: 257] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neural circuit function can be drastically affected by variations in the number of cells that are produced during development or by a reduction in adult cell number owing to disease. For this reason, unique cell cycle and cell growth control mechanisms operate in the developing and adult brain. In Drosophila melanogaster and in mammalian neural stem and progenitor cells, these mechanisms are intricately coordinated with the developmental age and the nutritional, metabolic and hormonal state of the animal. Defects in neural stem cell proliferation that result in the generation of incorrect cell numbers or defects in neural stem cell differentiation can cause microcephaly or megalencephaly.
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Affiliation(s)
- Catarina C F Homem
- Institute of Molecular Biotechnology, Dr. Bohr Gasse 3, 1030, Vienna, Austria.,Chronic Diseases Research Center, NOVA Medical School, Rua Camara Pestana, 6, 1150-082 Lisbon, Portugal
| | - Marko Repic
- Institute of Molecular Biotechnology, Dr. Bohr Gasse 3, 1030, Vienna, Austria
| | - Jürgen A Knoblich
- Institute of Molecular Biotechnology, Dr. Bohr Gasse 3, 1030, Vienna, Austria
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45
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Carvalho MJA, Mirth CK. Coordinating morphology with behavior during development: an integrative approach from a fly perspective. Front Ecol Evol 2015. [DOI: 10.3389/fevo.2015.00005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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46
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Apitz H, Salecker I. A Challenge of Numbers and Diversity: Neurogenesis in theDrosophilaOptic Lobe. J Neurogenet 2014; 28:233-49. [DOI: 10.3109/01677063.2014.922558] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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47
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Oliveira MM, Shingleton AW, Mirth CK. Coordination of wing and whole-body development at developmental milestones ensures robustness against environmental and physiological perturbations. PLoS Genet 2014; 10:e1004408. [PMID: 24945255 PMCID: PMC4063698 DOI: 10.1371/journal.pgen.1004408] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 04/14/2014] [Indexed: 11/18/2022] Open
Abstract
Development produces correctly patterned tissues under a wide range of conditions that alter the rate of development in the whole body. We propose two hypotheses through which tissue patterning could be coordinated with whole-body development to generate this robustness. Our first hypothesis states that tissue patterning is tightly coordinated with whole-body development over time. The second hypothesis is that tissue patterning aligns at developmental milestones. To distinguish between our two hypotheses, we developed a staging scheme for the wing imaginal discs of Drosophila larvae using the expression of canonical patterning genes, linking our scheme to three whole-body developmental events: moulting, larval wandering and pupariation. We used our scheme to explore how the progression of pattern changes when developmental time is altered either by changing temperature or by altering the timing of hormone synthesis that drives developmental progression. We found the expression pattern in the wing disc always aligned at moulting and pupariation, indicating that these key developmental events represent milestones. Between these milestones, the progression of pattern showed greater variability in response to changes in temperature and alterations in physiology. Furthermore, our data showed that discs from wandering larvae showed greater variability in patterning stage. Thus for wing disc patterning, wandering does not appear to be a developmental milestone. Our findings reveal that tissue patterning remains robust against environmental and physiological perturbations by aligning at developmental milestones. Furthermore, our work provides an important glimpse into how the development of individual tissues is coordinated with the body as a whole.
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Affiliation(s)
- Marisa M. Oliveira
- Development, Evolution and the Environment Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Alexander W. Shingleton
- Dept. of Zoology, Michigan State University, East Lansing, Michigan, United States of America
- Dept. of Biology, Lake Forest College, Lake Forest, Illinois, United States of America
| | - Christen K. Mirth
- Development, Evolution and the Environment Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
- * E-mail:
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48
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Lanet E, Maurange C. Building a brain under nutritional restriction: insights on sparing and plasticity from Drosophila studies. Front Physiol 2014; 5:117. [PMID: 24723892 PMCID: PMC3972452 DOI: 10.3389/fphys.2014.00117] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 03/10/2014] [Indexed: 11/13/2022] Open
Abstract
While the growth of the developing brain is known to be well-protected compared to other organs in the face of nutrient restriction (NR), careful analysis has revealed a range of structural alterations and long-term neurological defects. Yet, despite intensive studies, little is known about the basic principles that govern brain development under nutrient deprivation. For over 20 years, Drosophila has proved to be a useful model for investigating how a functional nervous system develops from a restricted number of neural stem cells (NSCs). Recently, a few studies have started to uncover molecular mechanisms as well as region-specific adaptive strategies that preserve brain functionality and neuronal repertoire under NR, while modulating neuron numbers. Here, we review the developmental constraints that condition the response of the developing brain to NR. We then analyze the recent Drosophila work to highlight key principles that drive sparing and plasticity in different regions of the central nervous system (CNS). As simple animal models start to build a more integrated picture, understanding how the developing brain copes with NR could help in defining strategies to limit damage and improve brain recovery after birth.
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Affiliation(s)
- Elodie Lanet
- Aix Marseille Université, CNRS, IBDM UMR 7288 Marseille, France
| | - Cédric Maurange
- Aix Marseille Université, CNRS, IBDM UMR 7288 Marseille, France
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49
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Love NK, Keshavan N, Lewis R, Harris WA, Agathocleous M. A nutrient-sensitive restriction point is active during retinal progenitor cell differentiation. Development 2014; 141:697-706. [PMID: 24449845 PMCID: PMC3899821 DOI: 10.1242/dev.103978] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In many growing tissues, slowly dividing stem cells give rise to rapidly proliferating progenitors that eventually exit the cell cycle and differentiate. Growth rates are limited by nutrient availability, but it is unclear which steps of the proliferation-differentiation programme are particularly sensitive to fuel supplies. We examined how nutrient deprivation (ND) affects stem and progenitor cells in the ciliary marginal zone (CMZ) of the amphibian retina, a well-characterised neurogenic niche. We show that ND specifically blocks the proliferation and differentiation of progenitor cells through an mTOR-mediated mechanism. By contrast, the identity and proliferation of retinal stem cells are insensitive to ND and mTOR inhibition. Re-feeding starved retinas in vitro rescues both proliferation and differentiation, and activation of mTOR is sufficient to stimulate differentiation even in ND retinas. These results suggest that an mTOR-mediated restriction point operates in vivo to couple nutrient abundance to the proliferation and differentiation programme in retinal progenitor cells.
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Affiliation(s)
- Nicola K Love
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
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50
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Shim J, Gururaja-Rao S, Banerjee U. Nutritional regulation of stem and progenitor cells in Drosophila. Development 2014; 140:4647-56. [PMID: 24255094 DOI: 10.1242/dev.079087] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Stem cells and their progenitors are maintained within a microenvironment, termed the niche, through local cell-cell communication. Systemic signals originating outside the niche also affect stem cell and progenitor behavior. This review summarizes studies that pertain to nutritional effects on stem and progenitor cell maintenance and proliferation in Drosophila. Multiple tissue types are discussed that utilize the insulin-related signaling pathway to convey nutritional information either directly to these progenitors or via other cell types within the niche. The concept of systemic control of these cell types is not limited to Drosophila and may be functional in vertebrate systems, including mammals.
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Affiliation(s)
- Jiwon Shim
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
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