1
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Thor S. Indirect neurogenesis in space and time. Nat Rev Neurosci 2024; 25:519-534. [PMID: 38951687 DOI: 10.1038/s41583-024-00833-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2024] [Indexed: 07/03/2024]
Abstract
During central nervous system (CNS) development, neural progenitor cells (NPCs) generate neurons and glia in two different ways. In direct neurogenesis, daughter cells differentiate directly into neurons or glia, whereas in indirect neurogenesis, neurons or glia are generated after one or more daughter cell divisions. Intriguingly, indirect neurogenesis is not stochastically deployed and plays instructive roles during CNS development: increased generation of cells from specific lineages; increased generation of early or late-born cell types within a lineage; and increased cell diversification. Increased indirect neurogenesis might contribute to the anterior CNS expansion evident throughout the Bilateria and help to modify brain-region size without requiring increased NPC numbers or extended neurogenesis. Increased indirect neurogenesis could be an evolutionary driver of the gyrencephalic (that is, folded) cortex that emerged during mammalian evolution and might even have increased during hominid evolution. Thus, selection of indirect versus direct neurogenesis provides a powerful developmental and evolutionary instrument that drives not only the evolution of CNS complexity but also brain expansion and modulation of brain-region size, and thereby the evolution of increasingly advanced cognitive abilities. This Review describes indirect neurogenesis in several model species and humans, and highlights some of the molecular genetic mechanisms that control this important process.
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Affiliation(s)
- Stefan Thor
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.
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2
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Lin KY, Gujar MR, Lin J, Ding WY, Huang J, Gao Y, Tan YS, Teng X, Christine LSL, Kanchanawong P, Toyama Y, Wang H. Astrocytes control quiescent NSC reactivation via GPCR signaling-mediated F-actin remodeling. SCIENCE ADVANCES 2024; 10:eadl4694. [PMID: 39047090 PMCID: PMC11268418 DOI: 10.1126/sciadv.adl4694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Accepted: 06/18/2024] [Indexed: 07/27/2024]
Abstract
The transitioning of neural stem cells (NSCs) between quiescent and proliferative states is fundamental for brain development and homeostasis. Defects in NSC reactivation are associated with neurodevelopmental disorders. Drosophila quiescent NSCs extend an actin-rich primary protrusion toward the neuropil. However, the function of the actin cytoskeleton during NSC reactivation is unknown. Here, we reveal the fine filamentous actin (F-actin) structures in the protrusions of quiescent NSCs by expansion and super-resolution microscopy. We show that F-actin polymerization promotes the nuclear translocation of myocardin-related transcription factor, a microcephaly-associated transcription factor, for NSC reactivation and brain development. F-actin polymerization is regulated by a signaling cascade composed of G protein-coupled receptor Smog, G protein αq subunit, Rho1 guanosine triphosphatase, and Diaphanous (Dia)/Formin during NSC reactivation. Further, astrocytes secrete a Smog ligand folded gastrulation to regulate Gαq-Rho1-Dia-mediated NSC reactivation. Together, we establish that the Smog-Gαq-Rho1 signaling axis derived from astrocytes, an NSC niche, regulates Dia-mediated F-actin dynamics in NSC reactivation.
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Affiliation(s)
- Kun-Yang Lin
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Mahekta R. Gujar
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Jiaen Lin
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Wei Yung Ding
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Jiawen Huang
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Yang Gao
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Ye Sing Tan
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Xiang Teng
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Low Siok Lan Christine
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Pakorn Kanchanawong
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Yusuke Toyama
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore, 117411, Singapore
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
| | - Hongyan Wang
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
- Integrative Sciences and Engineering Programme, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore
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3
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Lin KY, Gujar MR, Lin J, Ding WY, Huang J, Gao Y, Tan YS, Teng X, Christine LSL, Kanchanawong P, Toyama Y, Wang H. Astrocytes control quiescent NSC reactivation via GPCR signaling-mediated F-actin remodeling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.11.584337. [PMID: 38903085 PMCID: PMC11188063 DOI: 10.1101/2024.03.11.584337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
The transitioning of neural stem cells (NSCs) between quiescent and proliferative states is fundamental for brain development and homeostasis. Defects in NSC reactivation are associated with neurodevelopmental disorders. Drosophila quiescent NSCs extend an actin-rich primary protrusion toward the neuropil. However, the function of the actin cytoskeleton during NSC reactivation is unknown. Here, we reveal the fine F-actin structures in the protrusions of quiescent NSCs by expansion and super-resolution microscopy. We show that F-actin polymerization promotes the nuclear translocation of Mrtf, a microcephaly-associated transcription factor, for NSC reactivation and brain development. F-actin polymerization is regulated by a signaling cascade composed of G-protein-coupled receptor (GPCR) Smog, G-protein αq subunit, Rho1 GTPase, and Diaphanous (Dia)/Formin during NSC reactivation. Further, astrocytes secrete a Smog ligand Fog to regulate Gαq-Rho1-Dia-mediated NSC reactivation. Together, we establish that the Smog-Gαq-Rho1 signaling axis derived from astrocytes, a NSC niche, regulates Dia-mediated F-actin dynamics in NSC reactivation.
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4
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Voutyraki C, Choromidis A, Meligkounaki A, Vlachopoulos NA, Theodorou V, Grammenoudi S, Athanasiadis E, Monticelli S, Giangrande A, Delidakis C, Zacharioudaki E. Growth deregulation and interaction with host hemocytes contribute to tumor progression in a Drosophila brain tumor model. Proc Natl Acad Sci U S A 2023; 120:e2221601120. [PMID: 37549261 PMCID: PMC10438840 DOI: 10.1073/pnas.2221601120] [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: 12/23/2022] [Accepted: 06/27/2023] [Indexed: 08/09/2023] Open
Abstract
Tumors constantly interact with their microenvironment. Here, we present data on a Notch-induced neural stem cell (NSC) tumor in Drosophila, which can be immortalized by serial transplantation in adult hosts. This tumor arises in the larva by virtue of the ability of Notch to suppress early differentiation-promoting factors in NSC progeny. Guided by transcriptome data, we have addressed both tumor-intrinsic and microenvironment-specific factors and how they contribute to tumor growth and host demise. The growth promoting factors Myc, Imp, and Insulin receptor in the tumor cells are important for tumor expansion and killing of the host. From the host's side, hemocytes, professional phagocytic blood cells, are found associated with tumor cells. Phagocytic receptors, like NimC1, are needed in hemocytes to enable them to capture and engulf tumor cells, restricting their growth. In addition to their protective role, hemocytes may also increase the host's morbidity by their propensity to produce damaging extracellular reactive oxygen species.
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Affiliation(s)
- Chrysanthi Voutyraki
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013Heraklion, Crete, Greece
- Department of Biology, University of Crete, 70013Heraklion, Crete, Greece
| | - Alexandros Choromidis
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013Heraklion, Crete, Greece
- Department of Biology, University of Crete, 70013Heraklion, Crete, Greece
| | - Anastasia Meligkounaki
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013Heraklion, Crete, Greece
- Department of Biology, University of Crete, 70013Heraklion, Crete, Greece
| | - Nikolaos Andreas Vlachopoulos
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013Heraklion, Crete, Greece
- Department of Biology, University of Crete, 70013Heraklion, Crete, Greece
| | - Vasiliki Theodorou
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013Heraklion, Crete, Greece
| | - Sofia Grammenoudi
- Institute for Fundamental Biomedical Research, Biomedical Sciences Research Center Alexander Fleming, 16672Athens, Greece
| | - Emmanouil Athanasiadis
- Greek Genome Centre, Biomedical Research Foundation of the Academy of Athens, 11527Athens, Greece
- Medical Image and Signal Processing Laboratory, Department of Biomedical Engineering, University of West Attica, 12243Athens, Greece
| | - Sara Monticelli
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400Strasbourg, France
- Centre National de la Recherche Scientifique, UMR7104Strasbourg, France
- Institut National de la Santé et de la Recherche Médicale, U1258Strasbourg, France
- Université de Strasbourg, 67404Strasbourg, France
| | - Angela Giangrande
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400Strasbourg, France
- Centre National de la Recherche Scientifique, UMR7104Strasbourg, France
- Institut National de la Santé et de la Recherche Médicale, U1258Strasbourg, France
- Université de Strasbourg, 67404Strasbourg, France
| | - Christos Delidakis
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013Heraklion, Crete, Greece
- Department of Biology, University of Crete, 70013Heraklion, Crete, Greece
| | - Evanthia Zacharioudaki
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013Heraklion, Crete, Greece
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5
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Tang M, Regadas I, Belikov S, Shilkova O, Xu L, Wernersson E, Liu X, Wu H, Bienko M, Mannervik M. Separation of transcriptional repressor and activator functions in Drosophila HDAC3. Development 2023; 150:dev201548. [PMID: 37455638 PMCID: PMC10445730 DOI: 10.1242/dev.201548] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
The histone deacetylase HDAC3 is associated with the NCoR/SMRT co-repressor complex, and its canonical function is in transcriptional repression, but it can also activate transcription. Here, we show that the repressor and activator functions of HDAC3 can be genetically separated in Drosophila. A lysine substitution in the N terminus (K26A) disrupts its catalytic activity and activator function, whereas a combination of substitutions (HEBI) abrogating the interaction with SMRTER enhances repressor activity beyond wild type in the early embryo. We conclude that the crucial functions of HDAC3 in embryo development involve catalytic-dependent gene activation and non-enzymatic repression by several mechanisms, including tethering of loci to the nuclear periphery.
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Affiliation(s)
- Min Tang
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
- Department of Biochemistry and Molecular Biology, University of South China, 421001 Hengyang, China
| | - Isabel Regadas
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Sergey Belikov
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Olga Shilkova
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden
| | - Lei Xu
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17165 Stockholm, Sweden
- Science for Life Laboratory, 17165 Stockholm, Sweden
| | - Erik Wernersson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17165 Stockholm, Sweden
- Science for Life Laboratory, 17165 Stockholm, Sweden
| | - Xuewen Liu
- Department of Biochemistry and Molecular Biology, University of South China, 421001 Hengyang, China
| | - Hongmei Wu
- Department of Biochemistry and Molecular Biology, University of South China, 421001 Hengyang, China
| | - Magda Bienko
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17165 Stockholm, Sweden
- Science for Life Laboratory, 17165 Stockholm, Sweden
| | - Mattias Mannervik
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
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6
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Rajan A, Anhezini L, Rives-Quinto N, Chhabra JY, Neville MC, Larson ED, Goodwin SF, Harrison MM, Lee CY. Low-level repressive histone marks fine-tune gene transcription in neural stem cells. eLife 2023; 12:e86127. [PMID: 37314324 PMCID: PMC10344426 DOI: 10.7554/elife.86127] [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: 01/11/2023] [Accepted: 06/11/2023] [Indexed: 06/15/2023] Open
Abstract
Coordinated regulation of gene activity by transcriptional and translational mechanisms poise stem cells for a timely cell-state transition during differentiation. Although important for all stemness-to-differentiation transitions, mechanistic understanding of the fine-tuning of gene transcription is lacking due to the compensatory effect of translational control. We used intermediate neural progenitor (INP) identity commitment to define the mechanisms that fine-tune stemness gene transcription in fly neural stem cells (neuroblasts). We demonstrate that the transcription factor FruitlessC (FruC) binds cis-regulatory elements of most genes uniquely transcribed in neuroblasts. Loss of fruC function alone has no effect on INP commitment but drives INP dedifferentiation when translational control is reduced. FruC negatively regulates gene expression by promoting low-level enrichment of the repressive histone mark H3K27me3 in gene cis-regulatory regions. Identical to fruC loss-of-function, reducing Polycomb Repressive Complex 2 activity increases stemness gene activity. We propose low-level H3K27me3 enrichment fine-tunes gene transcription in stem cells, a mechanism likely conserved from flies to humans.
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Affiliation(s)
- Arjun Rajan
- Life Sciences Institute, University of Michigan-Ann ArborAnn ArborUnited States
| | - Lucas Anhezini
- Life Sciences Institute, University of Michigan-Ann ArborAnn ArborUnited States
| | - Noemi Rives-Quinto
- Life Sciences Institute, University of Michigan-Ann ArborAnn ArborUnited States
| | - Jay Y Chhabra
- Life Sciences Institute, University of Michigan-Ann ArborAnn ArborUnited States
| | - Megan C Neville
- Centre for Neural Circuits and Behaviour, University of OxfordOxfordUnited Kingdom
| | - Elizabeth D Larson
- Department of Biomolecular Chemistry, University of Wisconsin-MadisonMadisonUnited States
| | - Stephen F Goodwin
- Centre for Neural Circuits and Behaviour, University of OxfordOxfordUnited Kingdom
| | - Melissa M Harrison
- Department of Biomolecular Chemistry, University of Wisconsin-MadisonMadisonUnited States
| | - Cheng-Yu Lee
- Life Sciences Institute, University of Michigan-Ann ArborAnn ArborUnited States
- Department of Cell and Developmental Biology, University of Michigan Medical SchoolAnn ArborUnited States
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan Medical SchoolAnn ArborUnited States
- Rogel Cancer Center, University of Michigan Medical SchoolAnn ArborUnited States
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7
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Wang M, Ge J, Ma X, Su S, Tian C, Li J, Yu F, Li H, Song C, Gao J, Xu P, Tang Y, Xu G. Exploration of the regulatory mechanisms of regeneration, anti-oxidation, anti-aging and the immune response at the post-molt stage of Eriocheir sinensis. Front Physiol 2022; 13:948511. [PMID: 36237529 PMCID: PMC9552667 DOI: 10.3389/fphys.2022.948511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/22/2022] [Indexed: 12/03/2022] Open
Abstract
Eriocheir sinensis is widely appreciated by the surrounding population due to its culinary delicacy and rich nutrients. The E. sinensis breeding industry is very prosperous and molting is one of the important growth characteristics. Research on the regulation of molting in E. sinensis is still in the initial stages. There is currently no relevant information on the regulatory mechanisms of heart development following molting. Comparative transcriptome analysis was used to study developmental regulation mechanisms in the heart of E. sinensis at the post-molt and inter-molt stages. The results indicated that many regulatory pathways and genes involved in regeneration, anti-oxidation, anti-aging and the immune response were significantly upregulated after molting in E. sinensis. Aside from cardiac development, the differentially expressed genes (DEGs) were relevant to myocardial movement and neuronal signal transduction. DEGs were also related to the regulation of glutathione homeostasis and biological rhythms in regard to anti-oxidation and anti-aging, and to the regulation of immune cell development and the immune response. This study provides a theoretical framework for understanding the regulation of molting in E. sinensis and in other economically important crustaceans.
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Affiliation(s)
- Meiyao Wang
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
| | - Jiachun Ge
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing, China
| | - Xingkong Ma
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing, China
| | - Shengyan Su
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
| | - Can Tian
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Jianlin Li
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Fan Yu
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Hongxia Li
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
| | - Changyou Song
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
| | - Jiancao Gao
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Pao Xu
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
| | - Yongkai Tang
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
- *Correspondence: Yongkai Tang, ; Gangchun Xu,
| | - Gangchun Xu
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
- *Correspondence: Yongkai Tang, ; Gangchun Xu,
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8
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Zhu H, Zhao SD, Ray A, Zhang Y, Li X. A comprehensive temporal patterning gene network in Drosophila medulla neuroblasts revealed by single-cell RNA sequencing. Nat Commun 2022; 13:1247. [PMID: 35273186 PMCID: PMC8913700 DOI: 10.1038/s41467-022-28915-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 02/12/2022] [Indexed: 12/24/2022] Open
Abstract
During development, neural progenitors are temporally patterned to sequentially generate a variety of neural types. In Drosophila neural progenitors called neuroblasts, temporal patterning is regulated by cascades of Temporal Transcription Factors (TTFs). However, known TTFs were mostly identified through candidate approaches and may not be complete. In addition, many fundamental questions remain concerning the TTF cascade initiation, progression, and termination. In this work, we use single-cell RNA sequencing of Drosophila medulla neuroblasts of all ages to identify a list of previously unknown TTFs, and experimentally characterize their roles in temporal patterning and neuronal specification. Our study reveals a comprehensive temporal gene network that patterns medulla neuroblasts from start to end. Furthermore, the speed of the cascade progression is regulated by Lola transcription factors expressed in all medulla neuroblasts. Our comprehensive study of the medulla neuroblast temporal cascade illustrates mechanisms that may be conserved in the temporal patterning of neural progenitors. During development, neural progenitors generate a variety of neural types sequentially. Here the authors examine gene expression patterns in Drosophila neural progenitors at single-cell level, and identify a gene regulatory network controlling the sequential generation of different neural types.
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Affiliation(s)
- Hailun Zhu
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Sihai Dave Zhao
- Department of Statistics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Alokananda Ray
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yu Zhang
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Xin Li
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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9
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Hildebrandt K, Kübel S, Minet M, Fürst N, Klöppel C, Steinmetz E, Walldorf U. Enhancer analysis of the Drosophila zinc finger transcription factor Earmuff by gene targeting. Hereditas 2021; 158:41. [PMID: 34732265 PMCID: PMC8567707 DOI: 10.1186/s41065-021-00209-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/08/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Many transcription factors are involved in the formation of the brain during the development of Drosophila melanogaster. The transcription factor Earmuff (Erm), a member of the forebrain embryonic zinc finger family (Fezf), is one of these important factors for brain development. One major function of Earmuff is the regulation of proliferation within type II neuroblast lineages in the brain; here, Earmuff is expressed in intermediate neural progenitor cells (INPs) and balances neuronal differentiation versus stem cell maintenance. Erm expression during development is regulated by several enhancers. RESULTS In this work we show a functional analysis of erm and some of its enhancers. We generated a new erm mutant allele by gene targeting and reintegrated Gal4 to make an erm enhancer trap strain that could also be used on an erm mutant background. The deletion of three of the previously analysed enhancers showing the most prominent expression patterns of erm by gene targeting resulted in specific temporal and spatial defects in defined brain structures. These defects were already known but here could be assigned to specific enhancer regions. CONCLUSION This analysis is to our knowledge the first systematic analysis of several large enhancer deletions of a Drosophila gene by gene targeting and will enable deeper analysis of erm enhancer functions in the future.
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Affiliation(s)
- Kirsten Hildebrandt
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - Sabrina Kübel
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
- Present address: Clinical and Molecular Virology, Friedrich-Alexander University, 91054, Erlangen, Germany
| | - Marie Minet
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
- Present address: Human Genetics, Saarland University, Building 60, 66421, Homburg/Saar, Germany
| | - Nora Fürst
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
- Present address: Genetics/Epigenetics, Saarland University, Building A2.4, 66123, Saarbrücken, Germany
| | - Christine Klöppel
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - Eva Steinmetz
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
- Present address: Zoology and Physiology, Saarland University, Building B2.1, 66123, Saarbrücken, Germany
| | - Uwe Walldorf
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany.
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10
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Chen R, Hou Y, Connell M, Zhu S. Homeodomain protein Six4 prevents the generation of supernumerary Drosophila type II neuroblasts and premature differentiation of intermediate neural progenitors. PLoS Genet 2021; 17:e1009371. [PMID: 33556050 PMCID: PMC7895384 DOI: 10.1371/journal.pgen.1009371] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 02/19/2021] [Accepted: 01/15/2021] [Indexed: 11/19/2022] Open
Abstract
In order to boost the number and diversity of neurons generated from neural stem cells, intermediate neural progenitors (INPs) need to maintain their homeostasis by avoiding both dedifferentiation and premature differentiation. Elucidating how INPs maintain homeostasis is critical for understanding the generation of brain complexity and various neurological diseases resulting from defects in INP development. Here we report that Six4 expressed in Drosophila type II neuroblast (NB) lineages prevents the generation of supernumerary type II NBs and premature differentiation of INPs. We show that loss of Six4 leads to supernumerary type II NBs likely due to dedifferentiation of immature INPs (imINPs). We provide data to further demonstrate that Six4 inhibits the expression and activity of PntP1 in imINPs in part by forming a trimeric complex with Earmuff and PntP1. Furthermore, knockdown of Six4 exacerbates the loss of INPs resulting from the loss of PntP1 by enhancing ectopic Prospero expression in imINPs, suggesting that Six4 is also required for preventing premature differentiation of INPs. Taken together, our work identified a novel transcription factor that likely plays important roles in maintaining INP homeostasis. Intermediate neural progenitors (INPs) are descendants of neural stem cells that can proliferate for a short term to amplify the number of nerve cells generated in the brain. INPs play critical roles in determining how big and complex a brain can grow. To perform their function, INPs need to maintain their own population and must not adopt the identity of neural stem cells, a process called dedifferentiation, or acquire the fate of their own daughter cells and stop proliferation too soon, a process called premature differentiation. However, how INPs avoid dedifferentiation and premature differentiation is not fully understood. In this study, we identified a protein called Six4 as a novel factor that plays important roles in preventing the generation of extra neural stem cells and premature differentiation of INPs in developing fruit fly brains. We described how Six4 functionally and physically interacts with other factors that are involved in regulating INP cell fate specification. Our work provides novel insights into the mechanisms regulating INP development and could have important implications in understanding how complex brains are generated during normal development and how abnormal brain development or brain tumor can occur when INPs fail to avoid premature differentiation or dedifferentiation.
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Affiliation(s)
- Rui Chen
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York, United States of America
| | - Yanjun Hou
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York, United States of America
| | - Marisa Connell
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York, United States of America
| | - Sijun Zhu
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York, United States of America
- * E-mail:
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11
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Rives-Quinto N, Komori H, Ostgaard CM, Janssens DH, Kondo S, Dai Q, Moore AW, Lee CY. Sequential activation of transcriptional repressors promotes progenitor commitment by silencing stem cell identity genes. eLife 2020; 9:e56187. [PMID: 33241994 PMCID: PMC7728440 DOI: 10.7554/elife.56187] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 11/25/2020] [Indexed: 12/21/2022] Open
Abstract
Stem cells that indirectly generate differentiated cells through intermediate progenitors drives vertebrate brain evolution. Due to a lack of lineage information, how stem cell functionality, including the competency to generate intermediate progenitors, becomes extinguished during progenitor commitment remains unclear. Type II neuroblasts in fly larval brains divide asymmetrically to generate a neuroblast and a progeny that commits to an intermediate progenitor (INP) identity. We identified Tailless (Tll) as a master regulator of type II neuroblast functional identity, including the competency to generate INPs. Successive expression of transcriptional repressors functions through Hdac3 to silence tll during INP commitment. Reducing repressor activity allows re-activation of Notch in INPs to ectopically induce tll expression driving supernumerary neuroblast formation. Knocking-down hdac3 function prevents downregulation of tll during INP commitment. We propose that continual inactivation of stem cell identity genes allows intermediate progenitors to stably commit to generating diverse differentiated cells during indirect neurogenesis.
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Affiliation(s)
| | - Hideyuki Komori
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Cyrina M Ostgaard
- Life Sciences Institute, University of MichiganAnn ArborUnited States
- Department of Cell and Developmental Biology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Derek H Janssens
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Shu Kondo
- Invertebrate Genetics Laboratory, National Institute of GeneticsMishimaJapan
| | - Qi Dai
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm UniversityStockholmSweden
| | | | - Cheng-Yu Lee
- Life Sciences Institute, University of MichiganAnn ArborUnited States
- Department of Cell and Developmental Biology, University of Michigan Medical SchoolAnn ArborUnited States
- Division of Genetic Medicine, Department of Internal Medicine and Comprehensive Cancer Center, University of Michigan Medical SchoolAnn ArborUnited States
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12
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Magadi SS, Voutyraki C, Anagnostopoulos G, Zacharioudaki E, Poutakidou IK, Efraimoglou C, Stapountzi M, Theodorou V, Nikolaou C, Koumbanakis KA, Fullard JF, Delidakis C. Dissecting Hes-centred transcriptional networks in neural stem cell maintenance and tumorigenesis in Drosophila. Development 2020; 147:147/22/dev191544. [PMID: 33229432 DOI: 10.1242/dev.191544] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 10/05/2020] [Indexed: 01/26/2023]
Abstract
Neural stem cells divide during embryogenesis and juvenile life to generate the entire complement of neurons and glia in the nervous system of vertebrates and invertebrates. Studies of the mechanisms controlling the fine balance between neural stem cells and more differentiated progenitors have shown that, in every asymmetric cell division, progenitors send a Delta-Notch signal to their sibling stem cells. Here, we show that excessive activation of Notch or overexpression of its direct targets of the Hes family causes stem-cell hyperplasias in the Drosophila larval central nervous system, which can progress to malignant tumours after allografting to adult hosts. We combined transcriptomic data from these hyperplasias with chromatin occupancy data for Dpn, a Hes transcription factor, to identify genes regulated by Hes factors in this process. We show that the Notch/Hes axis represses a cohort of transcription factor genes. These are excluded from the stem cells and promote early differentiation steps, most likely by preventing the reversion of immature progenitors to a stem-cell fate. We describe the impact of two of these 'anti-stemness' factors, Zfh1 and Gcm, on Notch/Hes-triggered tumorigenesis.
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Affiliation(s)
- Srivathsa S Magadi
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece.,Department of Biology, University of Crete, 70013 Heraklion, Crete, Greece
| | - Chrysanthi Voutyraki
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece.,Department of Biology, University of Crete, 70013 Heraklion, Crete, Greece
| | - Gerasimos Anagnostopoulos
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece.,Department of Biology, University of Crete, 70013 Heraklion, Crete, Greece
| | - Evanthia Zacharioudaki
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece
| | - Ioanna K Poutakidou
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece.,Department of Biology, University of Crete, 70013 Heraklion, Crete, Greece
| | - Christina Efraimoglou
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece.,Department of Biology, University of Crete, 70013 Heraklion, Crete, Greece
| | - Margarita Stapountzi
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece
| | - Vasiliki Theodorou
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece
| | - Christoforos Nikolaou
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece.,Department of Biology, University of Crete, 70013 Heraklion, Crete, Greece
| | - Konstantinos A Koumbanakis
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece.,Department of Biology, University of Crete, 70013 Heraklion, Crete, Greece
| | - John F Fullard
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece
| | - Christos Delidakis
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 70013 Heraklion, Crete, Greece .,Department of Biology, University of Crete, 70013 Heraklion, Crete, Greece
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13
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Wang Y, Wang B, Shao X, Liu M, Jiang K, Wang M, Wang L. Identification and Profiling of MicroRNAs During Embryogenesis in the Red Claw Crayfish Cherax quadricarinatus. Front Physiol 2020; 11:878. [PMID: 33041835 PMCID: PMC7521159 DOI: 10.3389/fphys.2020.00878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 06/29/2020] [Indexed: 12/03/2022] Open
Abstract
MicroRNAs (miRNAs) are endogenous small non-coding RNAs that constitute a broad layer of gene regulation at both transcriptional and post-transcriptional levels from prokaryotes to eukaryotes. In embryonic development, they regulate the complex gene expression associated with the complexity of embryogenesis. There is little information about miRNAs in the red claw crayfish (Cherax quadricarinatus), an important commercial species and a potential biological model. In the present study, miRNAs and their target genes were identified during three embryonic developmental stages of C. quadricarinatus. Nineteen known miRNAs and 331 novel ones belonging to 50 miRNA families were obtained. A total of 113 differentially expressed miRNAs were identified, and 2,575 target genes were predicted, of which 1,257 were annotated. Additionally, 63 target genes of 9 miRNAs in C. quadricarinatus were found to be related to embryonic development. For example, miR-10 and its target genes may regulate the nervous system development and body segmentation and miR-2788 may regulate cell proliferation to impact embryonic development. Moreover, miR-28 (target gene tutl), miR-50 (target gene fbx5), and miR-1260b (target gene sif) may co-regulate eye development of embryonic C. quadricarinatus. These miRNAs together with their target genes constitute a network for regulating the development of tissues and organs in the embryo of C. quadricarinatus. Our results lay a foundation for further study on the fundamental molecular and developmental mechanism of crustacean embryogenesis.
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Affiliation(s)
- Yan Wang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Baojie Wang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
| | - Xuqing Shao
- Shandong Cigna Detection Technology Co., Ltd., Qingdao, China
| | - Mei Liu
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
| | - Keyong Jiang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
| | - Mengqiang Wang
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China.,National Laboratory for Marine Science and Technology, Center for Marine Molecular Biotechnology, Qingdao, China
| | - Lei Wang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,CAS Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, National Laboratory for Marine Science and Technology, Qingdao, China
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14
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Maurange C. Temporal patterning in neural progenitors: from Drosophila development to childhood cancers. Dis Model Mech 2020; 13:dmm044883. [PMID: 32816915 PMCID: PMC7390627 DOI: 10.1242/dmm.044883] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The developing central nervous system (CNS) is particularly prone to malignant transformation, but the underlying mechanisms remain unresolved. However, periods of tumor susceptibility appear to correlate with windows of increased proliferation, which are often observed during embryonic and fetal stages and reflect stereotypical changes in the proliferative properties of neural progenitors. The temporal mechanisms underlying these proliferation patterns are still unclear in mammals. In Drosophila, two decades of work have revealed a network of sequentially expressed transcription factors and RNA-binding proteins that compose a neural progenitor-intrinsic temporal patterning system. Temporal patterning controls both the identity of the post-mitotic progeny of neural progenitors, according to the order in which they arose, and the proliferative properties of neural progenitors along development. In addition, in Drosophila, temporal patterning delineates early windows of cancer susceptibility and is aberrantly regulated in developmental tumors to govern cellular hierarchy as well as the metabolic and proliferative heterogeneity of tumor cells. Whereas recent studies have shown that similar genetic programs unfold during both fetal development and pediatric brain tumors, I discuss, in this Review, how the concept of temporal patterning that was pioneered in Drosophila could help to understand the mechanisms of initiation and progression of CNS tumors in children.
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Affiliation(s)
- Cédric Maurange
- Aix Marseille University, CNRS, IBDM, Equipe Labellisée LIGUE Contre le Cancer, Marseille 13009, France
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15
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The Integrator Complex Prevents Dedifferentiation of Intermediate Neural Progenitors back into Neural Stem Cells. Cell Rep 2020; 27:987-996.e3. [PMID: 31018143 DOI: 10.1016/j.celrep.2019.03.089] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 01/31/2019] [Accepted: 03/24/2019] [Indexed: 01/08/2023] Open
Abstract
Mutations of the Integrator subunits are associated with neurodevelopmental disorders and cancers. However, their role during neural development is poorly understood. Here, we demonstrate that the Drosophila Integrator complex prevents dedifferentiation of intermediate neural progenitors (INPs) during neural stem cell (neuroblast) lineage development. Loss of intS5, intS8, and intS1 generated ectopic type II neuroblasts. INP-specific knockdown of intS8, intS1, and intS2 resulted in the formation of excess type II neuroblasts, indicating that Integrator prevents INP dedifferentiation. Cell-type-specific DamID analysis identified 1413 IntS5-binding sites in INPs, including zinc-finger transcription factor earmuff (erm). Furthermore, erm expression is lost in intS5 and intS8 mutant neuroblast lineages, and intS8 genetically interacts with erm to suppress the formation of ectopic neuroblasts. Taken together, our data demonstrate that the Drosophila Integrator complex plays a critical role in preventing INP dedifferentiation primarily by regulating a key transcription factor Erm that also suppresses INP dedifferentiation.
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16
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Ly PT, Wang H. Fzr/Cdh1 Promotes the Differentiation of Neural Stem Cell Lineages in Drosophila. Front Cell Dev Biol 2020; 8:60. [PMID: 32117986 PMCID: PMC7026481 DOI: 10.3389/fcell.2020.00060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/22/2020] [Indexed: 11/13/2022] Open
Abstract
How stem cells and progenitors balance between self-renewal and differentiation is a central issue of stem cell biology. Here, we describe a novel and essential function of Drosophila Fzr/Cdh1, an evolutionary conserved protein, during the differentiation of neural stem cell (NSC) lineages in the central nervous system. We show that Fzr, a known co-activator of Anaphase Promoting Complex/Cyclosome (APC/C) ubiquitin ligase, promotes the production of neurons from neural progenitors called ganglion mother cells (GMCs). However, knockdown of APC/C subunit Ida or another APC/C co-activator CDC20 does not similarly impair GMC-neuron transition. We also observe a concomitant loss of differentiation factor Prospero expression and ectopic accumulation of mitotic kinase Polo in fzr mutant clones, strongly supporting the impairment of GMC to neuron differentiation. Besides functioning in GMCs, Fzr is also present in NSCs to facilitate the production of intermediate neural progenitors from NSCs. Taken together, Fzr plays a novel function in promoting differentiation programs during Drosophila NSC lineage development. Given that human Fzr is inactivated in multiple types of human cancers including brain tumors and that Fzr regulates neurotoxicity in various models of neurodegenerative diseases, our study on the role of Fzr in turning off proliferation in neuronal cells may provide insights into how Fzr deficits may contribute to human neurodegenerative diseases and tumors.
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Affiliation(s)
- Phuong Thao Ly
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
| | - Hongyan Wang
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, Singapore, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
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17
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Genovese S, Clément R, Gaultier C, Besse F, Narbonne-Reveau K, Daian F, Foppolo S, Luis NM, Maurange C. Coopted temporal patterning governs cellular hierarchy, heterogeneity and metabolism in Drosophila neuroblast tumors. eLife 2019; 8:e50375. [PMID: 31566561 PMCID: PMC6791719 DOI: 10.7554/elife.50375] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 09/29/2019] [Indexed: 12/30/2022] Open
Abstract
It is still unclear what drives progression of childhood tumors. During Drosophila larval development, asymmetrically-dividing neural stem cells, called neuroblasts, progress through an intrinsic temporal patterning program that ensures cessation of divisions before adulthood. We previously showed that temporal patterning also delineates an early developmental window during which neuroblasts are susceptible to tumor initiation (Narbonne-Reveau et al., 2016). Using single-cell transcriptomics, clonal analysis and numerical modeling, we now identify a network of twenty larval temporal patterning genes that are redeployed within neuroblast tumors to trigger a robust hierarchical division scheme that perpetuates growth while inducing predictable cell heterogeneity. Along the hierarchy, temporal patterning genes define a differentiation trajectory that regulates glucose metabolism genes to determine the proliferative properties of tumor cells. Thus, partial redeployment of the temporal patterning program encoded in the cell of origin may govern the hierarchy, heterogeneity and growth properties of neural tumors with a developmental origin.
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Affiliation(s)
- Sara Genovese
- Aix Marseille Univ, CNRS, IBDM, Equipe Labellisée LIGUE Contre le CancerMarseilleFrance
| | - Raphaël Clément
- Aix Marseille Univ, CNRS, IBDM, Equipe Labellisée LIGUE Contre le CancerMarseilleFrance
| | - Cassandra Gaultier
- Aix Marseille Univ, CNRS, IBDM, Equipe Labellisée LIGUE Contre le CancerMarseilleFrance
| | - Florence Besse
- Université Côte d’Azur, CNRS, Inserm, Institut de Biologie ValroseNiceFrance
| | | | - Fabrice Daian
- Aix Marseille Univ, CNRS, IBDM, Equipe Labellisée LIGUE Contre le CancerMarseilleFrance
| | - Sophie Foppolo
- Aix Marseille Univ, CNRS, IBDM, Equipe Labellisée LIGUE Contre le CancerMarseilleFrance
| | - Nuno Miguel Luis
- Aix Marseille Univ, CNRS, IBDM, Equipe Labellisée LIGUE Contre le CancerMarseilleFrance
| | - Cédric Maurange
- Aix Marseille Univ, CNRS, IBDM, Equipe Labellisée LIGUE Contre le CancerMarseilleFrance
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18
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Hakes AE, Brand AH. Neural stem cell dynamics: the development of brain tumours. Curr Opin Cell Biol 2019; 60:131-138. [PMID: 31330360 DOI: 10.1016/j.ceb.2019.06.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/07/2019] [Accepted: 06/11/2019] [Indexed: 02/08/2023]
Abstract
Determining the premalignant lesions that develop into malignant tumours remains a daunting task. Brain tumours are frequently characterised by a block in differentiation, implying that normal developmental pathways become hijacked during tumourigenesis. However, the heterogeneity of stem cells and their progenitors in the brain suggests there are many potential routes to tumour initiation. Studies in Drosophila melanogaster have enhanced our understanding of the tumourigenic potential of distinct cell types in the brain. Here we review recent studies that have improved our knowledge of neural stem cell behaviour during development and in brain tumour models.
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Affiliation(s)
- Anna E Hakes
- 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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19
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Chubak MC, Nixon KCJ, Stone MH, Raun N, Rice SL, Sarikahya M, Jones SG, Lyons TA, Jakub TE, Mainland RLM, Knip MJ, Edwards TN, Kramer JM. Individual components of the SWI/SNF chromatin remodelling complex have distinct roles in memory neurons of the Drosophila mushroom body. Dis Model Mech 2019; 12:12/3/dmm037325. [PMID: 30923190 PMCID: PMC6451433 DOI: 10.1242/dmm.037325] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 02/23/2019] [Indexed: 12/13/2022] Open
Abstract
Technology has led to rapid progress in the identification of genes involved in neurodevelopmental disorders such as intellectual disability (ID), but our functional understanding of the causative genes is lagging. Here, we show that the SWI/SNF chromatin remodelling complex is one of the most over-represented cellular components disrupted in ID. We investigated the role of individual subunits of this large protein complex using targeted RNA interference in post-mitotic memory-forming neurons of the Drosophila mushroom body (MB). Knockdown flies were tested for defects in MB morphology, short-term memory and long-term memory. Using this approach, we identified distinct roles for individual subunits of the Drosophila SWI/SNF complex. Bap60, Snr1 and E(y)3 are required for pruning of the MBγ neurons during pupal morphogenesis, while Brm and Osa are required for survival of MBγ axons during ageing. We used the courtship conditioning assay to test the effect of MB-specific SWI/SNF knockdown on short- and long-term memory. Several subunits, including Brm, Bap60, Snr1 and E(y)3, were required in the MB for both short- and long-term memory. In contrast, Osa knockdown only reduced long-term memory. Our results suggest that individual components of the SWI/SNF complex have different roles in the regulation of structural plasticity, survival and functionality of post-mitotic MB neurons. This study highlights the many possible processes that might be disrupted in SWI/SNF-related ID disorders. Our broad phenotypic characterization provides a starting point for understanding SWI/SNF-mediated gene regulatory mechanisms that are important for development and function of post-mitotic neurons. Summary: The SWI/SNF chromatin remodelling complex is the most over-represented protein complex in the intellectual disability. Different components of this complex have distinct roles in development and function of memory-forming neurons in the Drosophila mushroom body.
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Affiliation(s)
- Melissa C Chubak
- Department of Biology, Faculty of Science, Western University, London, ON N6A 5B7, Canada
| | - Kevin C J Nixon
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Max H Stone
- Department of Biology, Faculty of Science, Western University, London, ON N6A 5B7, Canada.,Division of Genetics and Development, Children's Health Research Institute, London, ON N6C 2V5, Canada
| | - Nicholas Raun
- Department of Biology, Faculty of Science, Western University, London, ON N6A 5B7, Canada.,Division of Genetics and Development, Children's Health Research Institute, London, ON N6C 2V5, Canada
| | - Shelby L Rice
- Department of Biology, Faculty of Science, Western University, London, ON N6A 5B7, Canada
| | - Mohammed Sarikahya
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Spencer G Jones
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Taylor A Lyons
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Taryn E Jakub
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Roslyn L M Mainland
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Maria J Knip
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Tara N Edwards
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Jamie M Kramer
- Department of Biology, Faculty of Science, Western University, London, ON N6A 5B7, Canada .,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada.,Division of Genetics and Development, Children's Health Research Institute, London, ON N6C 2V5, Canada
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20
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Liu K, Xu K, Song Y. Faster, higher, stronger: timely and robust cell fate/identity commitment in stem cell lineages. Open Biol 2019; 9:180243. [PMID: 30958098 PMCID: PMC6395883 DOI: 10.1098/rsob.180243] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Precise specification of cell fate or identity within stem cell lineages is critical for ensuring correct stem cell lineage progression and tissue homeostasis. Failure to specify cell fate or identity in a timely and robust manner can result in developmental abnormalities and diseases such as cancer. However, the molecular basis of timely cell fate/identity specification is only beginning to be understood. In this review, we discuss key regulatory strategies employed in cell fate specification and highlight recent results revealing how timely and robust cell fate/identity commitment is achieved through transcriptional control.
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Affiliation(s)
- Kun Liu
- 1 Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences , Beijing 100871 , People's Republic of China.,2 Peking-Tsinghua Center for Life Sciences, Peking University , Beijing 100871 , People's Republic of China
| | - Ke Xu
- 1 Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences , Beijing 100871 , People's Republic of China
| | - Yan Song
- 1 Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences , Beijing 100871 , People's Republic of China.,2 Peking-Tsinghua Center for Life Sciences, Peking University , Beijing 100871 , People's Republic of China
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21
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Zacharioudaki E, Falo Sanjuan J, Bray S. Mi-2/NuRD complex protects stem cell progeny from mitogenic Notch signaling. eLife 2019; 8:41637. [PMID: 30694174 PMCID: PMC6379090 DOI: 10.7554/elife.41637] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 01/15/2019] [Indexed: 12/21/2022] Open
Abstract
To progress towards differentiation, progeny of stem cells need to extinguish expression of stem-cell maintenance genes. Failures in such mechanisms can drive tumorigenesis. In Drosophila neural stem cell (NSC) lineages, excessive Notch signalling results in supernumerary NSCs causing hyperplasia. However, onset of hyperplasia is considerably delayed implying there are mechanisms that resist the mitogenic signal. Monitoring the live expression of a Notch target gene, E(spl)mγ, revealed that normal attenuation is still initiated in the presence of excess Notch activity so that re-emergence of NSC properties occurs only in older progeny. Screening for factors responsible, we found that depletion of Mi-2/NuRD ATP remodeling complex dramatically enhanced Notch-induced hyperplasia. Under these conditions, E(spl)mγ was no longer extinguished in NSC progeny. We propose that Mi-2 is required for decommissioning stem-cell enhancers in their progeny, enabling the switch towards more differentiated fates and rendering them insensitive to mitogenic factors such as Notch.
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Affiliation(s)
- Evanthia Zacharioudaki
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Knigdom
| | - Julia Falo Sanjuan
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Knigdom
| | - Sarah Bray
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Knigdom
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22
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Guo Z, Qin J, Zhou X, Zhang Y. Insect Transcription Factors: A Landscape of Their Structures and Biological Functions in Drosophila and beyond. Int J Mol Sci 2018; 19:ijms19113691. [PMID: 30469390 PMCID: PMC6274879 DOI: 10.3390/ijms19113691] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 11/16/2018] [Accepted: 11/16/2018] [Indexed: 12/17/2022] Open
Abstract
Transcription factors (TFs) play essential roles in the transcriptional regulation of functional genes, and are involved in diverse physiological processes in living organisms. The fruit fly Drosophila melanogaster, a simple and easily manipulated organismal model, has been extensively applied to study the biological functions of TFs and their related transcriptional regulation mechanisms. It is noteworthy that with the development of genetic tools such as CRISPR/Cas9 and the next-generation genome sequencing techniques in recent years, identification and dissection the complex genetic regulatory networks of TFs have also made great progress in other insects beyond Drosophila. However, unfortunately, there is no comprehensive review that systematically summarizes the structures and biological functions of TFs in both model and non-model insects. Here, we spend extensive effort in collecting vast related studies, and attempt to provide an impartial overview of the progress of the structure and biological functions of current documented TFs in insects, as well as the classical and emerging research methods for studying their regulatory functions. Consequently, considering the importance of versatile TFs in orchestrating diverse insect physiological processes, this review will assist a growing number of entomologists to interrogate this understudied field, and to propel the progress of their contributions to pest control and even human health.
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Affiliation(s)
- Zhaojiang Guo
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
| | - Jianying Qin
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
- Longping Branch, Graduate School of Hunan University, Changsha 410125, China.
| | - Xiaomao Zhou
- Longping Branch, Graduate School of Hunan University, Changsha 410125, China.
| | - Youjun Zhang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
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23
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Harding K, White K. Drosophila as a Model for Developmental Biology: Stem Cell-Fate Decisions in the Developing Nervous System. J Dev Biol 2018; 6:E25. [PMID: 30347666 PMCID: PMC6315890 DOI: 10.3390/jdb6040025] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 10/16/2018] [Accepted: 10/17/2018] [Indexed: 12/25/2022] Open
Abstract
Stem cells face a diversity of choices throughout their lives. At specific times, they may decide to initiate cell division, terminal differentiation, or apoptosis, or they may enter a quiescent non-proliferative state. Neural stem cells in the Drosophila central nervous system do all of these, at stereotypical times and anatomical positions during development. Distinct populations of neural stem cells offer a unique system to investigate the regulation of a particular stem cell behavior, while comparisons between populations can lead us to a broader understanding of stem cell identity. Drosophila is a well-described and genetically tractable model for studying fundamental stem cell behavior and the mechanisms that underlie cell-fate decisions. This review will focus on recent advances in our understanding of the factors that contribute to distinct stem cell-fate decisions within the context of the Drosophila nervous system.
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Affiliation(s)
- Katherine Harding
- Massachusetts General Hospital Cutaneous Biology Research Center, Harvard Medical School, Boston, MA 02129, USA
| | - Kristin White
- Massachusetts General Hospital Cutaneous Biology Research Center, Harvard Medical School, Boston, MA 02129, USA.
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24
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Huang J, Wang H. Hsp83/Hsp90 Physically Associates with Insulin Receptor to Promote Neural Stem Cell Reactivation. Stem Cell Reports 2018; 11:883-896. [PMID: 30245208 PMCID: PMC6178561 DOI: 10.1016/j.stemcr.2018.08.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/21/2018] [Accepted: 08/21/2018] [Indexed: 12/14/2022] Open
Abstract
Neural stem cells (NSCs) have the ability to exit quiescence and reactivate in response to physiological stimuli. In the Drosophila brain, insulin receptor (InR)/phosphatidylinositol 3-kinase (PI3K)/Akt pathway triggers NSC reactivation. However, intrinsic mechanisms that control the InR/PI3K/Akt pathway during reactivation remain unknown. Here, we have identified heat shock protein 83 (Hsp83/Hsp90), a molecular chaperone, as an intrinsic regulator of NSC reactivation. Hsp83 is both necessary and sufficient for NSC reactivation by promoting the activation of InR pathway in larval brains in the presence of dietary amino acids. Both Hsp83 and its co-chaperone Cdc37 physically associate with InR. Finally, reactivation defects observed in brains depleted of hsp83 were rescued by over-activation of the InR/PI3K/Akt pathway, suggesting that Hsp83 functions upstream of the InR/PI3K/Akt pathway during NSC reactivation. Given the conservation of Hsp83 and the InR pathway, our finding may provide insights into the molecular mechanisms underlying mammalian NSC reactivation. Hsp83/Hsp90 and its co-chaperone Cdc37 are required for NSC reactivation Hsp83 overexpression results in premature NSC reactivation on fed condition Hsp83 and Cdc37 physically associate with InR Hsp83 and Cdc37 are required for the activation of InR pathway in NSCs
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Affiliation(s)
- Jiawen Huang
- Neuroscience & Behavioural Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Hongyan Wang
- Neuroscience & Behavioural Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore.
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25
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Jordán-Pla A, Yu S, Waldholm J, Källman T, Östlund Farrants AK, Visa N. SWI/SNF regulates half of its targets without the need of ATP-driven nucleosome remodeling by Brahma. BMC Genomics 2018; 19:367. [PMID: 29776334 PMCID: PMC5960078 DOI: 10.1186/s12864-018-4746-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/30/2018] [Indexed: 12/14/2022] Open
Abstract
Background Brahma (BRM) is the only catalytic subunit of the SWI/SNF chromatin-remodeling complex of Drosophila melanogaster. The function of SWI/SNF in transcription has long been attributed to its ability to remodel nucleosomes, which requires the ATPase activity of BRM. However, recent studies have provided evidence for a non-catalytic function of BRM in the transcriptional regulation of a few specific genes. Results Here we have used RNA-seq and ChIP-seq to identify the BRM target genes in S2 cells, and we have used a catalytically inactive BRM mutant (K804R) that is unable to hydrolyze ATP to investigate the magnitude of the non-catalytic function of BRM in transcription regulation. We show that 49% of the BRM target genes in S2 cells are regulated through mechanisms that do not require BRM to have an ATPase activity. We also show that the catalytic and non-catalytic mechanisms of SWI/SNF regulation operate on two subsets of genes that differ in promoter architecture and are linked to different biological processes. Conclusions This study shows that the non-catalytic role of SWI/SNF in transcription regulation is far more prevalent than previously anticipated and that the genes that are regulated by SWI/SNF through ATPase-dependent and ATPase-independent mechanisms have specialized roles in different cellular and developmental processes. Electronic supplementary material The online version of this article (10.1186/s12864-018-4746-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Antonio Jordán-Pla
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Simei Yu
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Johan Waldholm
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Thomas Källman
- Department of Medical Biochemistry and Microbiology, Uppsala University, SE-751 23, Uppsala, Sweden
| | - Ann-Kristin Östlund Farrants
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Neus Visa
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden.
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26
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Landskron L, Steinmann V, Bonnay F, Burkard TR, Steinmann J, Reichardt I, Harzer H, Laurenson AS, Reichert H, Knoblich JA. The asymmetrically segregating lncRNA cherub is required for transforming stem cells into malignant cells. eLife 2018; 7:31347. [PMID: 29580384 PMCID: PMC5871330 DOI: 10.7554/elife.31347] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 02/06/2018] [Indexed: 12/20/2022] Open
Abstract
Tumor cells display features that are not found in healthy cells. How they become immortal and how their specific features can be exploited to combat tumorigenesis are key questions in tumor biology. Here we describe the long non-coding RNA cherub that is critically required for the development of brain tumors in Drosophila but is dispensable for normal development. In mitotic Drosophila neural stem cells, cherub localizes to the cell periphery and segregates into the differentiating daughter cell. During tumorigenesis, de-differentiation of cherub-high cells leads to the formation of tumorigenic stem cells that accumulate abnormally high cherub levels. We show that cherub establishes a molecular link between the RNA-binding proteins Staufen and Syncrip. As Syncrip is part of the molecular machinery specifying temporal identity in neural stem cells, we propose that tumor cells proliferate indefinitely, because cherub accumulation no longer allows them to complete their temporal neurogenesis program. Many biological signals control how cells grow and divide. However, cancer cells do not obey these growth-restricting signals, and as a result large tumors may develop. Recent experiments have suggested that stem cells – the precursors to the different types of specialized cells found in the body – are particularly important for generating tumors. A stem cell normally divides unequally to form a self-renewing cell and a more specialized cell (often a progenitor cell that will give rise to increasingly specialized cell types). The timing of when the specialization occurs can be key to guiding the ultimately produced cell progenies to their final identity. However, in a tumor cells can retain the ability to self-renew. Ultimately, the resulting ‘tumor stem cells’ become immortal and proliferate indefinitely. It is not fully understood why this uncontrolled proliferation occurs. Just like mammals (including humans), fruit flies can develop tumors. Some of the DNA mutations responsible for tumor development were already identified in flies as early as in the 1970s. This has made fruit flies a well-studied model system for uncovering the principle defects that cause tumors to form. Landskron et al. have now studied the neural stem cells found in brain tumors in fruit flies. Additional DNA mutations were not responsible for these cells becoming immortal. Instead, certain RNA molecules – products that are ‘transcribed’ from the DNA – were present in different amounts in tumor cells. The RNA that showed the greatest increase in tumor cells is a so-called long non-coding RNA named cherub. This RNA molecule has no important role in normal fruit flies, but is critical for tumor formation. Landskron et al. found that during cell division cherub segregates from the neural stem cells to the newly formed progenitor cells, where it breaks down over time. Progenitor cells that contain high levels of cherub give rise to tumor-generating neural stem cells. At the molecular level, cherubhelps two proteins to interact with each other: one called Syncrip that makes the neural stem cells take on a older identity, and another one (Staufen) that tethers it to the cell membrane. By restricting Syncrip to a particular location in the cell, cherub alters the timing of stem cell specialization, which contributes to tumor formation. Overall, the results presented by Landskron et al. reveal a new role for long non-coding RNAs: controlling the localization of the proteins that determine the fate of the cell. They also highlight a critical link between the timing of stem cell development and the proliferation of the cells. Further work is now needed to test whether the same control mechanism works in species other than fruit flies.
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Affiliation(s)
- Lisa Landskron
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
| | - Victoria Steinmann
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
| | - Francois Bonnay
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
| | - Thomas R Burkard
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
| | - Jonas Steinmann
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
| | - Ilka Reichardt
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
| | - Heike Harzer
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
| | | | | | - Jürgen A Knoblich
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
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27
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Li X, Chen R, Zhu S. bHLH-O proteins balance the self-renewal and differentiation of Drosophila neural stem cells by regulating Earmuff expression. Dev Biol 2017; 431:239-251. [PMID: 28899667 DOI: 10.1016/j.ydbio.2017.09.011] [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: 04/21/2017] [Revised: 08/23/2017] [Accepted: 09/08/2017] [Indexed: 10/18/2022]
Abstract
Balancing self-renewal and differentiation of stem cells requires differential expression of self-renewing factors in two daughter cells generated from the asymmetric division of the stem cells. In Drosophila type II neural stem cell (or neuroblast, NB) lineages, the expression of the basic helix-loop-helix-Orange (bHLH-O) family proteins, including Deadpan (Dpn) and E(spl) proteins, is required for maintaining the self-renewal and identity of type II NBs, whereas the absence of these self-renewing factors is essential for the differentiation of intermediate neural progenitors (INPs) generated from type II NBs. Here, we demonstrate that Dpn maintains type II NBs by suppressing the expression of Earmuff (Erm). We provide evidence that Dpn and E(spl) proteins suppress Erm by directly binding to C-sites and N-boxes in the cis-regulatory region of erm. Conversely, the absence of bHLH-O proteins in INPs allows activation of erm and Erm-mediated maturation of INPs. Our results further suggest that Pointed P1 (PntP1) mediates the dedifferentiation of INPs resulting from the loss of Erm or overexpression of Dpn or E(spl) proteins. Taken together, these findings reveal mechanisms underlying the regulation of the maintenance of type II NBs and differentiation of INPs through the differential expression of bHLH-O family proteins.
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Affiliation(s)
- Xiaosu Li
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, United States
| | - Rui Chen
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, United States
| | - Sijun Zhu
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, United States.
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28
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Song S, Herranz H, Cohen SM. The chromatin remodeling BAP complex limits tumor-promoting activity of the Hippo pathway effector Yki to prevent neoplastic transformation in Drosophila epithelia. Dis Model Mech 2017; 10:1201-1209. [PMID: 28754838 PMCID: PMC5665456 DOI: 10.1242/dmm.030122] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/21/2017] [Indexed: 12/26/2022] Open
Abstract
Switch/sucrose non-fermentable (SWI/SNF) chromatin remodeling complexes are mutated in many human cancers. In this article, we make use of a Drosophila genetic model for epithelial tumor formation to explore the tumor suppressive role of SWI/SNF complex proteins. Members of the BAP complex exhibit tumor suppressor activity in tissue overexpressing the Yorkie (Yki) proto-oncogene, but not in tissue overexpressing epidermal growth factor receptor (EGFR). The Brahma-associated protein (BAP) complex has been reported to serve as a Yki-binding cofactor to support Yki target expression. However, we observed that depletion of BAP leads to ectopic expression of Yki targets both autonomously and non-autonomously, suggesting additional indirect effects. We provide evidence that BAP complex depletion causes upregulation of the Wingless (Wg) and Decapentaplegic (Dpp) morphogens to promote tumor formation in cooperation with Yki.
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Affiliation(s)
- Shilin Song
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, Copenhagen 2200N, Denmark
| | - Héctor Herranz
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, Copenhagen 2200N, Denmark
| | - Stephen M Cohen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, Copenhagen 2200N, Denmark
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29
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Li S, Koe CT, Tay ST, Tan ALK, Zhang S, Zhang Y, Tan P, Sung WK, Wang H. An intrinsic mechanism controls reactivation of neural stem cells by spindle matrix proteins. Nat Commun 2017; 8:122. [PMID: 28744001 PMCID: PMC5526931 DOI: 10.1038/s41467-017-00172-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 06/08/2017] [Indexed: 11/09/2022] Open
Abstract
The switch between quiescence and proliferation is central for neurogenesis and its alteration is linked to neurodevelopmental disorders such as microcephaly. However, intrinsic mechanisms that reactivate Drosophila larval neural stem cells (NSCs) to exit from quiescence are not well established. Here we show that the spindle matrix complex containing Chromator (Chro) functions as a key intrinsic regulator of NSC reactivation downstream of extrinsic insulin/insulin-like growth factor signalling. Chro also prevents NSCs from re-entering quiescence at later stages. NSC-specific in vivo profiling has identified many downstream targets of Chro, including a temporal transcription factor Grainy head (Grh) and a neural stem cell quiescence-inducing factor Prospero (Pros). We show that spindle matrix proteins promote the expression of Grh and repress that of Pros in NSCs to govern their reactivation. Our data demonstrate that nuclear Chro critically regulates gene expression in NSCs at the transition from quiescence to proliferation. The spindle matrix proteins, including Chro, are known to regulate mitotic spindle assembly in the cytoplasm. Here the authors show that in Drosophila larval brain, Chro promotes neural stem cell (NSC) reactivation and prevents activated NSCs from entering quiescence, and that Chro carries out such a role by regulating the expression of key transcription factors in the nucleus.
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Affiliation(s)
- Song Li
- Neuroscience & Behavioural Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Chwee Tat Koe
- Neuroscience & Behavioural Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Su Ting Tay
- Cancer & Stem Cell Biology Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Angie Lay Keng Tan
- Cancer & Stem Cell Biology Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Shenli Zhang
- Cancer & Stem Cell Biology Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Yingjie Zhang
- Neuroscience & Behavioural Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore, 117456, Singapore
| | - Patrick Tan
- Cancer & Stem Cell Biology Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore.,Cellular and Molecular Research, National Cancer Centre, Singapore, 169610, Singapore.,Cancer Science Institute of Singapore, National University of Singapore, Singapore, 119074, Singapore.,Genome Institute of Singapore, 60 Biopolis Street, Genome 02-01, Singapore, 138672, Singapore
| | - Wing-Kin Sung
- Genome Institute of Singapore, 60 Biopolis Street, Genome 02-01, Singapore, 138672, Singapore.,Department of Computer Science, National University of Singapore, Singapore, 117417, Singapore
| | - Hongyan Wang
- Neuroscience & Behavioural Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore. .,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore, 117456, Singapore. .,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Singapore.
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30
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Liu K, Shen D, Shen J, Gao SM, Li B, Wong C, Feng W, Song Y. The Super Elongation Complex Drives Neural Stem Cell Fate Commitment. Dev Cell 2017; 40:537-551.e6. [PMID: 28350987 DOI: 10.1016/j.devcel.2017.02.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 01/13/2017] [Accepted: 02/26/2017] [Indexed: 10/19/2022]
Abstract
Asymmetric stem cell division establishes an initial difference between a stem cell and its differentiating sibling, critical for maintaining homeostasis and preventing carcinogenesis. Yet the mechanisms that consolidate and lock in such initial fate bias remain obscure. Here, we use Drosophila neuroblasts to demonstrate that the super elongation complex (SEC) acts as an intrinsic amplifier to drive cell fate commitment. SEC is highly expressed in neuroblasts, where it promotes self-renewal by physically associating with Notch transcription activation complex and enhancing HES (hairy and E(spl)) transcription. HES in turn upregulates SEC activity, forming an unexpected self-reinforcing feedback loop with SEC. SEC inactivation leads to neuroblast loss, whereas its forced activation results in neural progenitor dedifferentiation and tumorigenesis. Our studies unveil an SEC-mediated intracellular amplifier mechanism in ensuring robustness and precision in stem cell fate commitment and provide mechanistic explanation for the highly frequent association of SEC overactivation with human cancers.
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Affiliation(s)
- Kun Liu
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Dan Shen
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Jingwen Shen
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Shihong M Gao
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Bo Li
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Chouin Wong
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Weidong Feng
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Yan Song
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
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31
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Janssens DH, Hamm DC, Anhezini L, Xiao Q, Siller KH, Siegrist SE, Harrison MM, Lee CY. An Hdac1/Rpd3-Poised Circuit Balances Continual Self-Renewal and Rapid Restriction of Developmental Potential during Asymmetric Stem Cell Division. Dev Cell 2017; 40:367-380.e7. [PMID: 28245922 DOI: 10.1016/j.devcel.2017.01.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 12/16/2016] [Accepted: 01/27/2017] [Indexed: 10/20/2022]
Abstract
How the developmental potential of differentiating stem cell progeny becomes rapidly and stably restricted following asymmetric stem cell division is unclear. In the fly larval brain, earmuff (erm) uniquely functions to restrict the developmental potential of intermediate neural progenitors (INPs) generated by asymmetrically dividing neural stem cells (neuroblasts). Here we demonstrate that the histone deacetylase Hdac1/Rpd3 functions together with self-renewal transcriptional repressors to maintain the erm immature INP enhancer in an inactive but poised state in neuroblasts. Within 2 hr of immature INP birth, downregulation of repressor activities alleviates Rpd3-mediated repression on the erm enhancer, enabling acetylation of multiple histone proteins and activating Erm expression. Erm restricts the developmental potential in immature INPs by repressing genes encoding neuroblast transcriptional activators. We propose that poising the fast-activating enhancers of master regulators of differentiation through continual histone deacetylation in stem cells enables self-renewal and rapid restriction of developmental potential following asymmetric division.
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Affiliation(s)
- Derek H Janssens
- Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Danielle C Hamm
- Department of Biomolecular Chemistry, University of Wisconsin - Madison, Madison, WI 53706, USA
| | - Lucas Anhezini
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Qi Xiao
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Karsten H Siller
- Advanced Research Computing Services, University of Virginia, Charlottesville, VA 22904, USA
| | - Sarah E Siegrist
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Melissa M Harrison
- Department of Biomolecular Chemistry, University of Wisconsin - Madison, Madison, WI 53706, USA
| | - Cheng-Yu Lee
- Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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32
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Farnsworth DR, Doe CQ. Opportunities lost and gained: Changes in progenitor competence during nervous system development. NEUROGENESIS 2017; 4:e1324260. [PMID: 28656157 DOI: 10.1080/23262133.2017.1324260] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 04/20/2017] [Accepted: 04/24/2017] [Indexed: 02/07/2023]
Abstract
During development of the central nervous system, a small pool of stem cells and progenitors generate the vast neural diversity required for neural circuit formation and behavior. Neural stem and progenitor cells often generate different progeny in response to the same signaling cue (e.g. Notch or Hedgehog), including no response at all. How does stem cell competence to respond to signaling cues change over time? Recently, epigenetics particularly chromatin remodeling - has emerged as a powerful mechanism to control stem cell competence. Here we review recent Drosophila and vertebrate literature describing the effect of epigenetic changes on neural stem cell competence.
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Affiliation(s)
- Dylan R Farnsworth
- Howard Hughes Medical Institute, University of Oregon, Eugene, OR, USA.,Institute of Molecular Biology, University of Oregon, Eugene, OR, USA
| | - Chris Q Doe
- Howard Hughes Medical Institute, University of Oregon, Eugene, OR, USA.,Institute of Molecular Biology, University of Oregon, Eugene, OR, USA.,Institute of Neuroscience, University of Oregon, Eugene, OR, USA
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33
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Xu J, Hao X, Yin MX, Lu Y, Jin Y, Xu J, Ge L, Wu W, Ho M, Yang Y, Zhao Y, Zhang L. Prevention of medulla neuron dedifferentiation by Nerfin-1 requires inhibition of Notch activity. Development 2017; 144:1510-1517. [PMID: 28242614 DOI: 10.1242/dev.141341] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 02/17/2017] [Indexed: 11/20/2022]
Abstract
The Drosophila larval central nervous system comprises the central brain, ventral nerve cord and optic lobe. In these regions, neuroblasts (NBs) divide asymmetrically to self-renew and generate differentiated neurons or glia. To date, mechanisms of preventing neuron dedifferentiation are still unclear, especially in the optic lobe. Here, we show that the zinc-finger transcription factor Nerfin-1 is expressed in early-stage medulla neurons and is essential for maintaining their differentiation. Loss of Nerfin-1 activates Notch signaling, which promotes neuron-to-NB reversion. Repressing Notch signaling largely rescues dedifferentiation in nerfin-1 mutant clones. Thus, we conclude that Nerfin-1 represses Notch activity in medulla neurons and prevents them from dedifferentiation.
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Affiliation(s)
- Jiajun Xu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China
| | - Xue Hao
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China
| | - Meng-Xin Yin
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China
| | - Yi Lu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China
| | - Yunyun Jin
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China
| | - Jinjin Xu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China
| | - Ling Ge
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China
| | - Wenqing Wu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China
| | - Margaret Ho
- Department of Anatomy and Neurobiology, Tongji University, School of Medicine, Shanghai 200092, People's Republic of China
| | - Yingzi Yang
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Yun Zhao
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China.,School of Life Science and Technology, ShanghaiTech University, Shanghai 200031, People's Republic of China
| | - Lei Zhang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, People's Republic of China .,School of Life Science and Technology, ShanghaiTech University, Shanghai 200031, People's Republic of China
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34
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Paglia S, Sollazzo M, Di Giacomo S, de Biase D, Pession A, Grifoni D. Failure of the PTEN/aPKC/Lgl Axis Primes Formation of Adult Brain Tumours in Drosophila. BIOMED RESEARCH INTERNATIONAL 2017; 2017:2690187. [PMID: 29445734 PMCID: PMC5763105 DOI: 10.1155/2017/2690187] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/02/2017] [Accepted: 11/08/2017] [Indexed: 02/05/2023]
Abstract
Different regions in the mammalian adult brain contain immature precursors, reinforcing the concept that brain cancers, such as glioblastoma multiforme (GBM), may originate from cells endowed with stem-like properties. Alterations of the tumour suppressor gene PTEN are very common in primary GBMs. Very recently, PTEN loss was shown to undermine a specific molecular axis, whose failure is associated with the maintenance of the GBM stem cells in mammals. This axis is composed of PTEN, aPKC, and the polarity determinant Lethal giant larvae (Lgl): PTEN loss promotes aPKC activation through the PI3K pathway, which in turn leads to Lgl inhibition, ultimately preventing stem cell differentiation. To find the neural precursors responding to perturbations of this molecular axis, we targeted different neurogenic regions of the Drosophila brain. Here we show that PTEN mutation impacts aPKC and Lgl protein levels also in Drosophila. Moreover, we demonstrate that PI3K activation is not sufficient to trigger tumourigenesis, while aPKC promotes hyperplastic growth of the neuroepithelium and a noticeable expansion of the type II neuroblasts. Finally, we show that these neuroblasts form invasive tumours that persist and keep growing in the adult, leading the affected animals to untimely death, thus displaying frankly malignant behaviours.
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Affiliation(s)
- Simona Paglia
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Manuela Sollazzo
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Simone Di Giacomo
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Dario de Biase
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Annalisa Pession
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Daniela Grifoni
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
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35
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Xie G, Chen H, Jia D, Shu Z, Palmer WH, Huang YC, Zeng X, Hou SX, Jiao R, Deng WM. The SWI/SNF Complex Protein Snr1 Is a Tumor Suppressor in Drosophila Imaginal Tissues. Cancer Res 2016; 77:862-873. [PMID: 27923836 DOI: 10.1158/0008-5472.can-16-0963] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 11/02/2016] [Accepted: 11/18/2016] [Indexed: 12/17/2022]
Abstract
Components of the SWI/SNF chromatin-remodeling complex are among the most frequently mutated genes in various human cancers, yet only SMARCB1/hSNF5, a core member of the SWI/SNF complex, is mutated in malignant rhabdoid tumors (MRT). How SMARCB1/hSNF5 functions differently from other members of the SWI/SNF complex remains unclear. Here, we use Drosophila imaginal epithelial tissues to demonstrate that Snr1, the conserved homolog of human SMARCB1/hSNF5, prevents tumorigenesis by maintaining normal endosomal trafficking-mediated signaling cascades. Removal of Snr1 resulted in neoplastic tumorigenic overgrowth in imaginal epithelial tissues, whereas depletion of any other members of the SWI/SNF complex did not induce similar phenotypes. Unlike other components of the SWI/SNF complex that were detected only in the nucleus, Snr1 was observed in both the nucleus and the cytoplasm. Aberrant regulation of multiple signaling pathways, including Notch, JNK, and JAK/STAT, was responsible for tumor progression upon snr1-depletion. Our results suggest that the cytoplasmic Snr1 may play a tumor suppressive role in Drosophila imaginal tissues, offering a foundation for understanding the pivotal role of SMARCB1/hSNF5 in suppressing MRT during early childhood. Cancer Res; 77(4); 862-73. ©2017 AACR.
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Affiliation(s)
- Gengqiang Xie
- Department of Biological Science, Florida State University, Tallahassee, Florida
| | - Hanqing Chen
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China
| | - Dongyu Jia
- Department of Biological Science, Florida State University, Tallahassee, Florida
| | - Zhiqiang Shu
- Department of Biological Science, Florida State University, Tallahassee, Florida
| | - William Hunt Palmer
- Department of Biological Science, Florida State University, Tallahassee, Florida
| | - Yi-Chun Huang
- Department of Biological Science, Florida State University, Tallahassee, Florida
| | - Xiankun Zeng
- The Basic Research Laboratory, National Cancer Institute, National Institutes of Health, Frederick, Maryland
| | - Steven X Hou
- The Basic Research Laboratory, National Cancer Institute, National Institutes of Health, Frederick, Maryland
| | - Renjie Jiao
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China. .,Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
| | - Wu-Min Deng
- Department of Biological Science, Florida State University, Tallahassee, Florida.
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36
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Xie Y, Li X, Deng X, Hou Y, O'Hara K, Urso A, Peng Y, Chen L, Zhu S. The Ets protein Pointed prevents both premature differentiation and dedifferentiation of Drosophila intermediate neural progenitors. Development 2016; 143:3109-18. [PMID: 27510969 DOI: 10.1242/dev.137281] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 07/27/2016] [Indexed: 01/01/2023]
Abstract
Intermediate neural progenitors (INPs) need to avoid both dedifferentiation and differentiation during neurogenesis, but the underlying mechanisms are not well understood. In Drosophila, the Ets protein Pointed P1 (PntP1) is required to generate INPs from type II neuroblasts. Here, we investigated how PntP1 promotes INP generation. By generating pntP1-specific mutants and using RNAi knockdown, we show that the loss of PntP1 leads to both an increase in type II neuroblast number and the elimination of INPs. The elimination of INPs results from the premature differentiation of INPs due to ectopic Prospero expression in newly generated immature INPs (imINPs), whereas the increase in type II neuroblasts results from the dedifferentiation of imINPs due to loss of Earmuff at later stages of imINP development. Furthermore, reducing Buttonhead enhances the loss of INPs in pntP1 mutants, suggesting that PntP1 and Buttonhead act cooperatively to prevent premature INP differentiation. Our results demonstrate that PntP1 prevents both the premature differentiation and the dedifferentiation of INPs by regulating the expression of distinct target genes at different stages of imINP development.
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Affiliation(s)
- Yonggang Xie
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Xiaosu Li
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Xiaobing Deng
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Yanjun Hou
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Krysten O'Hara
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | | | - Ying Peng
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Li Chen
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Sijun Zhu
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
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37
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Wang H, Bierie B, Li AG, Pathania S, Toomire K, Dimitrov SD, Liu B, Gelman R, Giobbie-Hurder A, Feunteun J, Polyak K, Livingston DM. BRCA1/FANCD2/BRG1-Driven DNA Repair Stabilizes the Differentiation State of Human Mammary Epithelial Cells. Mol Cell 2016; 63:277-292. [PMID: 27373334 DOI: 10.1016/j.molcel.2016.05.038] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 04/11/2016] [Accepted: 05/26/2016] [Indexed: 10/21/2022]
Abstract
An abnormal differentiation state is common in BRCA1-deficient mammary epithelial cells, but the underlying mechanism is unclear. Here, we report a convergence between DNA repair and normal, cultured human mammary epithelial (HME) cell differentiation. Surprisingly, depleting BRCA1 or FANCD2 (Fanconi anemia [FA] proteins) or BRG1, a mSWI/SNF subunit, caused HME cells to undergo spontaneous epithelial-to-mesenchymal transition (EMT) and aberrant differentiation. This also occurred when wild-type HMEs were exposed to chemicals that generate DNA interstrand crosslinks (repaired by FA proteins), but not in response to double-strand breaks. Suppressed expression of ΔNP63 also occurred in each of these settings, an effect that links DNA damage to the aberrant differentiation outcome. Taken together with somatic breast cancer genome data, these results point to a breakdown in a BRCA/FA-mSWI/SNF-ΔNP63-mediated DNA repair and differentiation maintenance process in mammary epithelial cells that may contribute to sporadic breast cancer development.
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Affiliation(s)
- Hua Wang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
| | - Brian Bierie
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Andrew G Li
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Shailja Pathania
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Kimberly Toomire
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Stoil D Dimitrov
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Ben Liu
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Rebecca Gelman
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Anita Giobbie-Hurder
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Jean Feunteun
- Stabilité Génétique et Oncogenèse, Université Paris-Sud, CNRS-UMR8200, Gustave-Roussy, Villejuif 94805, France
| | - Kornelia Polyak
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA
| | - David M Livingston
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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38
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Narbonne-Reveau K, Lanet E, Dillard C, Foppolo S, Chen CH, Parrinello H, Rialle S, Sokol NS, Maurange C. Neural stem cell-encoded temporal patterning delineates an early window of malignant susceptibility in Drosophila. eLife 2016; 5:e13463. [PMID: 27296804 PMCID: PMC4907696 DOI: 10.7554/elife.13463] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 05/26/2016] [Indexed: 12/30/2022] Open
Abstract
Pediatric neural tumors are often initiated during early development and can undergo very rapid transformation. However, the molecular basis of this early malignant susceptibility remains unknown. During Drosophila development, neural stem cells (NSCs) divide asymmetrically and generate intermediate progenitors that rapidly differentiate in neurons. Upon gene inactivation, these progeny can dedifferentiate and generate malignant tumors. Here, we find that intermediate progenitors are prone to malignancy only when born during an early window of development while expressing the transcription factor Chinmo, and the mRNA-binding proteins Imp/IGF2BP and Lin-28. These genes compose an oncogenic module that is coopted upon dedifferentiation of early-born intermediate progenitors to drive unlimited tumor growth. In late larvae, temporal transcription factor progression in NSCs silences the module, thereby limiting mitotic potential and terminating the window of malignant susceptibility. Thus, this study identifies the gene regulatory network that confers malignant potential to neural tumors with early developmental origins.
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Affiliation(s)
| | - Elodie Lanet
- Aix Marseille Univ, CNRS, IBDM, Marseille, France
| | | | | | - Ching-Huan Chen
- Department of Biology, Indiana University, Bloomington, United States
| | - Hugues Parrinello
- MGX-Montpellier GenomiX, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Stéphanie Rialle
- MGX-Montpellier GenomiX, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Nicholas S Sokol
- Department of Biology, Indiana University, Bloomington, United States
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39
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Li X, Xie Y, Zhu S. Notch maintains Drosophila type II neuroblasts by suppressing expression of the Fez transcription factor Earmuff. Development 2016; 143:2511-21. [PMID: 27151950 DOI: 10.1242/dev.136184] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/26/2016] [Indexed: 01/10/2023]
Abstract
Notch signaling is crucial for maintaining neural stem cell (NSC) self-renewal and heterogeneity; however, the underlying mechanism is not well understood. In Drosophila, loss of Notch prematurely terminates the self-renewal of larval type II neuroblasts (NBs, the Drosophila NSCs) and transforms type II NBs into type I NBs. Here, we demonstrate that Notch maintains type II NBs by suppressing the activation of earmuff (erm) by Pointed P1 (PntP1). We show that loss of Notch or components of its canonical pathway leads to PntP1-dependent ectopic Erm expression in type II NBs. Knockdown of Erm significantly rescues the loss-of-Notch phenotypes, and misexpression of Erm phenocopies the loss of Notch. Ectopically expressed Erm promotes the transformation of type II NBs into type I NBs by inhibiting PntP1 function and expression in type II NBs. Our work not only elucidates a key mechanism of Notch-mediated maintenance of type II NB self-renewal and identity, but also reveals a novel function of Erm.
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Affiliation(s)
- Xiaosu Li
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Yonggang Xie
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Sijun Zhu
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
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40
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Zhang Y, Rai M, Wang C, Gonzalez C, Wang H. Prefoldin and Pins synergistically regulate asymmetric division and suppress dedifferentiation. Sci Rep 2016; 6:23735. [PMID: 27025979 PMCID: PMC4812327 DOI: 10.1038/srep23735] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/14/2016] [Indexed: 01/14/2023] Open
Abstract
Prefoldin is a molecular chaperone complex that regulates tubulin function in mitosis. Here, we show that Prefoldin depletion results in disruption of neuroblast polarity, leading to neuroblast overgrowth in Drosophila larval brains. Interestingly, co-depletion of Prefoldin and Partner of Inscuteable (Pins) leads to the formation of gigantic brains with severe neuroblast overgrowth, despite that Pins depletion alone results in smaller brains with partially disrupted neuroblast polarity. We show that Prefoldin acts synergistically with Pins to regulate asymmetric division of both neuroblasts and Intermediate Neural Progenitors (INPs). Surprisingly, co-depletion of Prefoldin and Pins also induces dedifferentiation of INPs back into neuroblasts, while depletion either Prefoldin or Pins alone is insufficient to do so. Furthermore, knocking down either α-tubulin or β-tubulin in pins- mutant background results in INP dedifferentiation back into neuroblasts, leading to the formation of ectopic neuroblasts. Overexpression of α-tubulin suppresses neuroblast overgrowth observed in prefoldin pins double mutant brains. Our data elucidate an unexpected function of Prefoldin and Pins in synergistically suppressing dedifferentiation of INPs back into neural stem cells.
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Affiliation(s)
- Yingjie Zhang
- Neuroscience &Behavioral Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore 169857.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456
| | - Madhulika Rai
- Institute for Research in Biomedicine (IRB-Barcelona), Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Cheng Wang
- Neuroscience &Behavioral Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore 169857
| | - Cayetano Gonzalez
- Institute for Research in Biomedicine (IRB-Barcelona), Baldiri Reixac 10, 08028 Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA). Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Hongyan Wang
- Neuroscience &Behavioral Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore 169857.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456.,Dept. of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597
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41
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Abstract
How stem cells produce the huge diversity of neurons that form the visual system, and how these cells are assembled in neural circuits are a critical question in developmental neurobiology. Investigations in Drosophila have led to the discovery of several basic principles of neural patterning. In this chapter, we provide an overview of the field by describing the development of the Drosophila visual system, from the embryo to the adult and from the gross anatomy to the cellular level. We then explore the general molecular mechanisms identified that might apply to other neural structures in flies or in vertebrates. Finally, we discuss the major challenges that remain to be addressed in the field.
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Affiliation(s)
- Nathalie Nériec
- Center for Genomics & Systems Biology, New York University, Abu Dhabi, UAE; Department of Biology, New York University, New York, USA
| | - Claude Desplan
- Center for Genomics & Systems Biology, New York University, Abu Dhabi, UAE; Department of Biology, New York University, New York, USA.
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42
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Farnsworth DR, Bayraktar OA, Doe CQ. Aging Neural Progenitors Lose Competence to Respond to Mitogenic Notch Signaling. Curr Biol 2015; 25:3058-68. [PMID: 26585279 DOI: 10.1016/j.cub.2015.10.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 10/07/2015] [Accepted: 10/12/2015] [Indexed: 12/21/2022]
Abstract
Drosophila neural stem cells (neuroblasts) are a powerful model system for investigating stem cell self-renewal, specification of temporal identity, and progressive restriction in competence. Notch signaling is a conserved cue that is an important determinant of cell fate in many contexts across animal development; for example, mammalian T cell differentiation in the thymus and neuroblast specification in Drosophila are both regulated by Notch signaling. However, Notch also functions as a mitogen, and constitutive Notch signaling potentiates T cell leukemia as well as Drosophila neuroblast tumors. While the role of Notch signaling has been studied in these and other cell types, it remains unclear how stem cells and progenitors change competence to respond to Notch over time. Notch is required in type II neuroblasts for normal development of their transit amplifying progeny, intermediate neural progenitors (INPs). Here, we find that aging INPs lose competence to respond to constitutively active Notch signaling. Moreover, we show that reducing the levels of the old INP temporal transcription factor Eyeless/Pax6 allows Notch signaling to promote the de-differentiation of INP progeny into ectopic INPs, thereby creating a proliferative mass of ectopic progenitors in the brain. These findings provide a new system for studying progenitor competence and identify a novel role for the conserved transcription factor Eyeless/Pax6 in blocking Notch signaling during development.
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Affiliation(s)
- Dylan R Farnsworth
- Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Omer Ali Bayraktar
- Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
| | - Chris Q Doe
- Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA.
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43
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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: 234] [Impact Index Per Article: 26.0] [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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44
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Xie Y, Li X, Zhang X, Mei S, Li H, Urso A, Zhu S. The Drosophila Sp8 transcription factor Buttonhead prevents premature differentiation of intermediate neural progenitors. eLife 2014; 3. [PMID: 25285448 PMCID: PMC4221738 DOI: 10.7554/elife.03596] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 09/28/2014] [Indexed: 11/13/2022] Open
Abstract
Intermediate neural progenitor cells (INPs) need to avoid differentiation and cell cycle exit while maintaining restricted developmental potential, but mechanisms preventing differentiation and cell cycle exit of INPs are not well understood. In this study, we report that the Drosophila homolog of mammalian Sp8 transcription factor Buttonhead (Btd) prevents premature differentiation and cell cycle exit of INPs in Drosophila larval type II neuroblast (NB) lineages. We show that the loss of Btd leads to elimination of mature INPs due to premature differentiation of INPs into terminally dividing ganglion mother cells. We provide evidence to demonstrate that Btd prevents the premature differentiation by suppressing the expression of the homeodomain protein Prospero in immature INPs. We further show that Btd functions cooperatively with the Ets transcription factor Pointed P1 to promote the generation of INPs. Thus, our work reveals a critical mechanism that prevents premature differentiation and cell cycle exit of Drosophila INPs.
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Affiliation(s)
- Yonggang Xie
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, United States
| | - Xiaosu Li
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, United States
| | - Xian Zhang
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, United States
| | - Shaolin Mei
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, United States
| | - Hongyu Li
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, United States
| | | | - Sijun Zhu
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, United States
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Komori H, Xiao Q, Janssens DH, Dou Y, Lee CY. Trithorax maintains the functional heterogeneity of neural stem cells through the transcription factor buttonhead. eLife 2014; 3. [PMID: 25285447 PMCID: PMC4221733 DOI: 10.7554/elife.03502] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 10/03/2014] [Indexed: 01/24/2023] Open
Abstract
The mechanisms that maintain the functional heterogeneity of stem cells, which generates diverse differentiated cell types required for organogenesis, are not understood. In this study, we report that Trithorax (Trx) actively maintains the heterogeneity of neural stem cells (neuroblasts) in the developing Drosophila larval brain. trx mutant type II neuroblasts gradually adopt a type I neuroblast functional identity, losing the competence to generate intermediate neural progenitors (INPs) and directly generating differentiated cells. Trx regulates a type II neuroblast functional identity in part by maintaining chromatin in the buttonhead (btd) locus in an active state through the histone methyltransferase activity of the SET1/MLL complex. Consistently, btd is necessary and sufficient for eliciting a type II neuroblast functional identity. Furthermore, over-expression of btd restores the competence to generate INPs in trx mutant type II neuroblasts. Thus, Trx instructs a type II neuroblast functional identity by epigenetically promoting Btd expression, thereby maintaining neuroblast functional heterogeneity. DOI:http://dx.doi.org/10.7554/eLife.03502.001 Whereas the majority of cells in the brain are unable to divide to produce new cells, neural stem cells can divide numerous times and have the potential to become many different types of brain cells. However, between these two extremes there is another group of cells called neural progenitors. These cells can give rise to multiple types of neurons but, in contrast to stem cells, they can undergo only a limited number of divisions. Many of the molecular mechanisms by which stem cells give rise to progenitors are similar in mammals and in the fruit fly Drosophila. In the brains of fly larvae, a subset of neural stem cells called type II neuroblasts give rise to ‘intermediate neural progenitors’, each of which can divide between four and six times. Every division generates a replacement intermediate neural progenitor and a cell called a ganglion mother cell, which divides one last time to produce two brain cells. Thus, intermediate neural progenitors increase the overall output of cells derived from every division of a type II neuroblast. The ability of type II neuroblasts to generate intermediate neural progenitors is important for development. Loss of this ability will result in a shortage of cells, disrupting brain development, while the faulty generation of intermediate neural progenitors will result in the formation of tumors. Now, using Drosophila brain cells cultured in the laboratory, Komori et al. show that an evolutionarily conserved enzyme called Trithorax has an important role in maintaining this ability. Trithorax acts through a protein called Buttonhead. The role of Buttonhead in regulating intermediate neural progenitors has also been identified by Xie et al. Komori et al. show that type II neuroblasts that lack Trithorax activity lose their unique identity and behave as type I neuroblasts, which never generate intermediate neural progenitors. Trithorax maintains the cellular memory of a type II neuroblast by keeping regions of chromatin—a macromolecule made of DNA and proteins called histones—in an active state. These regions contain key genes, such as the gene for Buttonhead. Re-introducing Buttonhead in type II neuroblasts that lack Trithorax activity can reinstate their ability to produce intermediate neural progenitors. DOI:http://dx.doi.org/10.7554/eLife.03502.002
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Affiliation(s)
- Hideyuki Komori
- Center for Stem Cell Biology, Life Sciences Institute, University of Michigan Medical School, Ann Arbor, United States
| | - Qi Xiao
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Derek H Janssens
- Program in Cell and Molecular Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Yali Dou
- Department of Pathology, University of Michigan Medical School, Ann Arbor, United States
| | - Cheng-Yu Lee
- Center for Stem Cell Biology, Life Sciences Institute, University of Michigan Medical School, Ann Arbor, United States
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Drosophila neuroblasts as a new model for the study of stem cell self-renewal and tumour formation. Biosci Rep 2014; 34:BSR20140008. [PMID: 24965943 PMCID: PMC4114065 DOI: 10.1042/bsr20140008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Drosophila larval brain stem cells (neuroblasts) have emerged as an important model for the study of stem cell asymmetric division and the mechanisms underlying the transformation of neural stem cells into tumour-forming cancer stem cells. Each Drosophila neuroblast divides asymmetrically to produce a larger daughter cell that retains neuroblast identity, and a smaller daughter cell that is committed to undergo differentiation. Neuroblast self-renewal and differentiation are tightly controlled by a set of intrinsic factors that regulate ACD (asymmetric cell division). Any disruption of these two processes may deleteriously affect the delicate balance between neuroblast self-renewal and progenitor cell fate specification and differentiation, causing neuroblast overgrowth and ultimately lead to tumour formation in the fly. In this review, we discuss the mechanisms underlying Drosophila neural stem cell self-renewal and differentiation. Furthermore, we highlight emerging evidence in support of the notion that defects in ACD in mammalian systems, which may play significant roles in the series of pathogenic events leading to the development of brain cancers.
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Taniguchi H, Moore AW. Chromatin regulators in neurodevelopment and disease: Analysis of fly neural circuits provides insights. Bioessays 2014; 36:872-83. [DOI: 10.1002/bies.201400087] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Hiroaki Taniguchi
- Laboratory for Genetic Code; Graduate School of Life and Medical Sciences; Doshisha University; Kyotanabe Kyoto Japan
| | - Adrian W. Moore
- Laboratory for Genetic Control of Neuronal Architecture; RIKEN Brain Science Institute; Wako-shi Saitama Japan
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Eckler MJ, Chen B. Fez family transcription factors: controlling neurogenesis and cell fate in the developing mammalian nervous system. Bioessays 2014; 36:788-97. [PMID: 24913420 DOI: 10.1002/bies.201400039] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Fezf1 and Fezf2 are highly conserved transcription factors that were first identified by their specific expression in the anterior neuroepithelium of Xenopus and zebrafish embryos. These proteins share an N-terminal domain with homology to the canonical engrailed repressor motif and a C-terminal DNA binding domain containing six C2H2 zinc-finger repeats. Over a decade of study indicates that the Fez proteins play critical roles during nervous system development in species as diverse as fruit flies and mice. Herein we discuss recent progress in understanding the functions of Fezf1 and Fezf2 in neurogenesis and cell fate specification during mammalian nervous system development. Going forward we believe that efforts should focus on understanding how expression of these factors is precisely regulated, and on identifying target DNA sequences and interacting partners. Such knowledge may reveal the mechanisms by which Fezf1 and Fezf2 accomplish both independent and redundant functions across diverse tissue and cell types.
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Affiliation(s)
- Matthew J Eckler
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA, USA
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