1
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Veen K, Krylov A, Yu S, He J, Boyd P, Hyde DR, Mantamadiotis T, Cheng LY, Jusuf PR. Her6 and Prox1a are novel regulators of photoreceptor regeneration in the zebrafish retina. PLoS Genet 2023; 19:e1011010. [PMID: 37930995 PMCID: PMC10653607 DOI: 10.1371/journal.pgen.1011010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 11/16/2023] [Accepted: 10/03/2023] [Indexed: 11/08/2023] Open
Abstract
Damage to light-sensing photoreceptors (PRs) occurs in highly prevalent retinal diseases. As humans cannot regenerate new PRs, these diseases often lead to irreversible blindness. Intriguingly, animals, such as the zebrafish, can regenerate PRs efficiently and restore functional vision. Upon injury, mature Müller glia (MG) undergo reprogramming to adopt a stem cell-like state. This process is similar to cellular dedifferentiation, and results in the generation of progenitor cells, which, in turn, proliferate and differentiate to replace lost retinal neurons. In this study, we tested whether factors involved in dedifferentiation of Drosophila CNS are implicated in the regenerative response in the zebrafish retina. We found that hairy-related 6 (her6) negatively regulates of PR production by regulating the rate of cell divisions in the MG-derived progenitors. prospero homeobox 1a (prox1a) is expressed in differentiated PRs and may promote PR differentiation through phase separation. Interestingly, upon Her6 downregulation, Prox1a is precociously upregulated in the PRs, to promote PR differentiation; conversely, loss of Prox1a also induces a downregulation of Her6. Together, we identified two novel candidates of PR regeneration that cross regulate each other; these may be exploited to promote human retinal regeneration and vision recovery.
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Affiliation(s)
- Kellie Veen
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
- School of BioSciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Aaron Krylov
- School of BioSciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Shuguang Yu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Centre for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Jie He
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Centre for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Patrick Boyd
- Department of Biological Sciences, Center for Zebrafish Research, and Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - David R. Hyde
- Department of Biological Sciences, Center for Zebrafish Research, and Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Theo Mantamadiotis
- Department of Microbiology and Immunology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Louise Y. Cheng
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Patricia R. Jusuf
- School of BioSciences, The University of Melbourne, Melbourne, Victoria, Australia
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2
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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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3
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Cao Y. Neural induction drives body axis formation during embryogenesis, but a neural induction-like process drives tumorigenesis in postnatal animals. Front Cell Dev Biol 2023; 11:1092667. [PMID: 37228646 PMCID: PMC10203556 DOI: 10.3389/fcell.2023.1092667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 04/17/2023] [Indexed: 05/27/2023] Open
Abstract
Characterization of cancer cells and neural stem cells indicates that tumorigenicity and pluripotency are coupled cell properties determined by neural stemness, and tumorigenesis represents a process of progressive loss of original cell identity and gain of neural stemness. This reminds of a most fundamental process required for the development of the nervous system and body axis during embryogenesis, i.e., embryonic neural induction. Neural induction is that, in response to extracellular signals that are secreted by the Spemann-Mangold organizer in amphibians or the node in mammals and inhibit epidermal fate in ectoderm, the ectodermal cells lose their epidermal fate and assume the neural default fate and consequently, turn into neuroectodermal cells. They further differentiate into the nervous system and also some non-neural cells via interaction with adjacent tissues. Failure in neural induction leads to failure of embryogenesis, and ectopic neural induction due to ectopic organizer or node activity or activation of embryonic neural genes causes a formation of secondary body axis or a conjoined twin. During tumorigenesis, cells progressively lose their original cell identity and gain of neural stemness, and consequently, gain of tumorigenicity and pluripotency, due to various intra-/extracellular insults in cells of a postnatal animal. Tumorigenic cells can be induced to differentiation into normal cells and integrate into normal embryonic development within an embryo. However, they form tumors and cannot integrate into animal tissues/organs in a postnatal animal because of lack of embryonic inducing signals. Combination of studies of developmental and cancer biology indicates that neural induction drives embryogenesis in gastrulating embryos but a similar process drives tumorigenesis in a postnatal animal. Tumorigenicity is by nature the manifestation of aberrant occurrence of pluripotent state in a postnatal animal. Pluripotency and tumorigenicity are both but different manifestations of neural stemness in pre- and postnatal stages of animal life, respectively. Based on these findings, I discuss about some confusion in cancer research, propose to distinguish the causality and associations and discriminate causal and supporting factors involved in tumorigenesis, and suggest revisiting the focus of cancer research.
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Affiliation(s)
- Ying Cao
- Shenzhen Research Institute of Nanjing University, Shenzhen, China
- MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
- Jiangsu Key Laboratory of Molecular Medicine of Medical School, Nanjing University, Nanjing, China
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4
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Sato M, Suzuki T. Cutting edge technologies expose the temporal regulation of neurogenesis in the Drosophila nervous system. Fly (Austin) 2022; 16:222-232. [PMID: 35549651 PMCID: PMC9116403 DOI: 10.1080/19336934.2022.2073158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 04/28/2022] [Accepted: 04/28/2022] [Indexed: 11/23/2022] Open
Abstract
During the development of the central nervous system (CNS), extremely large numbers of neurons are produced in a regular fashion to form precise neural circuits. During this process, neural progenitor cells produce different neurons over time due to their intrinsic gene regulatory mechanisms as well as extrinsic mechanisms. The Drosophila CNS has played an important role in elucidating the temporal mechanisms that control neurogenesis over time. It has been shown that a series of temporal transcription factors are sequentially expressed in neural progenitor cells and regulate the temporal specification of neurons in the embryonic CNS. Additionally, similar mechanisms are found in the developing optic lobe and central brain in the larval CNS. However, it is difficult to elucidate the function of numerous molecules in many different cell types solely by molecular genetic approaches. Recently, omics analysis using single-cell RNA-seq and other methods has been used to study the Drosophila nervous system on a large scale and is making a significant contribution to the understanding of the temporal mechanisms of neurogenesis. In this article, recent findings on the temporal patterning of neurogenesis and the contributions of cutting-edge technologies will be reviewed.
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Affiliation(s)
- Makoto Sato
- Mathematical Neuroscience Unit, Institute for Frontier Science Initiative,Laboratory of Developmental Neurobiology, Graduate School of Medical Sciences, Kanazawa University, Ishikawa, Japan
| | - Takumi Suzuki
- College of Science, Department of Science, Ibaraki University, Ibaraki, Japan
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5
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Zhao T, Xiao Y, Huang B, Ran MJ, Duan X, Wang YF, Lu Y, Yu XQ. A dual role of lola in Drosophila ovary development: regulating stem cell niche establishment and repressing apoptosis. Cell Death Dis 2022; 13:756. [PMID: 36056003 PMCID: PMC9440207 DOI: 10.1038/s41419-022-05195-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 08/13/2022] [Accepted: 08/17/2022] [Indexed: 01/21/2023]
Abstract
In Drosophila ovary, niche is composed of somatic cells, including terminal filament cells (TFCs), cap cells (CCs) and escort cells (ECs), which provide extrinsic signals to maintain stem cell renewal or initiate cell differentiation. Niche establishment begins in larval stages when terminal filaments (TFs) are formed, but the underlying mechanism for the development of TFs remains largely unknown. Here we report that transcription factor longitudinals lacking (Lola) is essential for ovary morphogenesis. We showed that Lola protein was expressed abundantly in TFCs and CCs, although also in other cells, and lola was required for the establishment of niche during larval stage. Importantly, we found that knockdown expression of lola induced apoptosis in adult ovary, and that lola affected adult ovary morphogenesis by suppressing expression of Regulator of cullins 1b (Roc1b), an apoptosis-related gene that regulates caspase activation during spermatogenesis. These findings significantly expand our understanding of the mechanisms controlling niche establishment and adult oogenesis in Drosophila.
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Affiliation(s)
- Ting Zhao
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Yanhong Xiao
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, South China Normal University, Guangzhou, PR China
| | - Bo Huang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Mao-Jiu Ran
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Xin Duan
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Yu-Feng Wang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Yuzhen Lu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, South China Normal University, Guangzhou, PR China.
| | - Xiao-Qiang Yu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, South China Normal University, Guangzhou, PR China.
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6
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Zhang M, Liu Y, Shi L, Fang L, Xu L, Cao Y. Neural stemness unifies cell tumorigenicity and pluripotent differentiation potential. J Biol Chem 2022; 298:102106. [PMID: 35671824 PMCID: PMC9254501 DOI: 10.1016/j.jbc.2022.102106] [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: 02/04/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/16/2022] Open
Abstract
Neural stemness is suggested to be the ground state of tumorigenicity and pluripotent differentiation potential. However, the relationship between these cell properties is unclear. Here, by disrupting the neural regulatory network in neural stem and cancer cells and by serial transplantation of cancer cells, we show that tumorigenicity and pluripotent differentiation potential are coupled cell properties unified by neural stemness. We show that loss of neural stemness via inhibition of SETDB1, an oncoprotein with enriched expression in embryonic neural cells during vertebrate embryogenesis, led to neuronal differentiation with reduced tumorigenicity and pluripotent differentiation potential in neural stem and cancer cells, whereas enhancement of neural stemness by SETDB1 overexpression caused the opposite effects. SETDB1 maintains a regulatory network comprising proteins involved in developmental programs and basic cellular functional machineries, including epigenetic modifications (EZH2), ribosome biogenesis (RPS3), translation initiation (EIF4G), and spliceosome assembly (SF3B1); all of these proteins are enriched in embryonic neural cells and play active roles in cancers. In addition, SETDB1 represses the transcription of genes promoting differentiation and cell cycle and growth arrest. Serial transplantation of cancer cells showed that neural stemness, tumorigenicity, and pluripotent differentiation potential were simultaneously enhanced; these effects were accompanied by increased expression of proteins involved in developmental programs and basic machineries, including SETDB1 and the abovementioned proteins, as well as by increased alternative splicing events. These results indicate that basic machineries work together to define a highly proliferative state with pluripotent differentiation potential and also suggest that neural stemness unifies tumorigenicity and differentiation potential.
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Affiliation(s)
- Min Zhang
- Shenzhen Research Institute of Nanjing University, Shenzhen, China; MOE Key Laboratory of Model Animals for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center of Medical School
| | - Yang Liu
- Shenzhen Research Institute of Nanjing University, Shenzhen, China; MOE Key Laboratory of Model Animals for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center of Medical School
| | - Lihua Shi
- MOE Key Laboratory of Model Animals for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center of Medical School
| | - Lei Fang
- Jiangsu Key Laboratory of Molecular Medicine of Medical School, Nanjing University, Nanjing, China
| | - Liyang Xu
- MOE Key Laboratory of Model Animals for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center of Medical School
| | - Ying Cao
- Shenzhen Research Institute of Nanjing University, Shenzhen, China; MOE Key Laboratory of Model Animals for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center of Medical School.
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7
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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: 20] [Impact Index Per Article: 10.0] [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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8
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Wei L, Lai EC. Regulation of the Alternative Neural Transcriptome by ELAV/Hu RNA Binding Proteins. Front Genet 2022; 13:848626. [PMID: 35281806 PMCID: PMC8904962 DOI: 10.3389/fgene.2022.848626] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 02/01/2022] [Indexed: 11/30/2022] Open
Abstract
The process of alternative polyadenylation (APA) generates multiple 3' UTR isoforms for a given locus, which can alter regulatory capacity and on occasion change coding potential. APA was initially characterized for a few genes, but in the past decade, has been found to be the rule for metazoan genes. While numerous differences in APA profiles have been catalogued across genetic conditions, perturbations, and diseases, our knowledge of APA mechanisms and biology is far from complete. In this review, we highlight recent findings regarding the role of the conserved ELAV/Hu family of RNA binding proteins (RBPs) in generating the broad landscape of lengthened 3' UTRs that is characteristic of neurons. We relate this to their established roles in alternative splicing, and summarize ongoing directions that will further elucidate the molecular strategies for neural APA, the in vivo functions of ELAV/Hu RBPs, and the phenotypic consequences of these regulatory paradigms in neurons.
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Affiliation(s)
- Lu Wei
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Eric C. Lai
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, United States
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9
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Janssens J, Aibar S, Taskiran II, Ismail JN, Gomez AE, Aughey G, Spanier KI, De Rop FV, González-Blas CB, Dionne M, Grimes K, Quan XJ, Papasokrati D, Hulselmans G, Makhzami S, De Waegeneer M, Christiaens V, Southall T, Aerts S. Decoding gene regulation in the fly brain. Nature 2022; 601:630-636. [PMID: 34987221 DOI: 10.1038/s41586-021-04262-z] [Citation(s) in RCA: 71] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 11/17/2021] [Indexed: 12/13/2022]
Abstract
The Drosophila brain is a frequently used model in neuroscience. Single-cell transcriptome analysis1-6, three-dimensional morphological classification7 and electron microscopy mapping of the connectome8,9 have revealed an immense diversity of neuronal and glial cell types that underlie an array of functional and behavioural traits in the fly. The identities of these cell types are controlled by gene regulatory networks (GRNs), involving combinations of transcription factors that bind to genomic enhancers to regulate their target genes. Here, to characterize GRNs at the cell-type level in the fly brain, we profiled the chromatin accessibility of 240,919 single cells spanning 9 developmental timepoints and integrated these data with single-cell transcriptomes. We identify more than 95,000 regulatory regions that are used in different neuronal cell types, of which 70,000 are linked to developmental trajectories involving neurogenesis, reprogramming and maturation. For 40 cell types, uniquely accessible regions were associated with their expressed transcription factors and downstream target genes through a combination of motif discovery, network inference and deep learning, creating enhancer GRNs. The enhancer architectures revealed by DeepFlyBrain lead to a better understanding of neuronal regulatory diversity and can be used to design genetic driver lines for cell types at specific timepoints, facilitating their characterization and manipulation.
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Affiliation(s)
- Jasper Janssens
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Sara Aibar
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Ibrahim Ihsan Taskiran
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Joy N Ismail
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | | | - Gabriel Aughey
- Department of Life Sciences, Imperial College London, London, UK
| | - Katina I Spanier
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Florian V De Rop
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Carmen Bravo González-Blas
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Marc Dionne
- Department of Life Sciences, Imperial College London, London, UK
| | - Krista Grimes
- Department of Life Sciences, Imperial College London, London, UK
| | - Xiao Jiang Quan
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Dafni Papasokrati
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Gert Hulselmans
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Samira Makhzami
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Maxime De Waegeneer
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Valerie Christiaens
- VIB Center for Brain & Disease Research, Leuven, Belgium.,Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Tony Southall
- Department of Life Sciences, Imperial College London, London, UK
| | - Stein Aerts
- VIB Center for Brain & Disease Research, Leuven, Belgium. .,Department of Human Genetics, KU Leuven, Leuven, Belgium.
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10
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Avetisyan A, Glatt Y, Cohen M, Timerman Y, Aspis N, Nachman A, Halachmi N, Preger-Ben Noon E, Salzberg A. Delilah, prospero, and D-Pax2 constitute a gene regulatory network essential for the development of functional proprioceptors. eLife 2021; 10:70833. [PMID: 34964712 PMCID: PMC8716109 DOI: 10.7554/elife.70833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 12/03/2021] [Indexed: 12/03/2022] Open
Abstract
Coordinated animal locomotion depends on the development of functional proprioceptors. While early cell-fate determination processes are well characterized, little is known about the terminal differentiation of cells within the proprioceptive lineage and the genetic networks that control them. In this work we describe a gene regulatory network consisting of three transcription factors–Prospero (Pros), D-Pax2, and Delilah (Dei)–that dictates two alternative differentiation programs within the proprioceptive lineage in Drosophila. We show that D-Pax2 and Pros control the differentiation of cap versus scolopale cells in the chordotonal organ lineage by, respectively, activating and repressing the transcription of dei. Normally, D-Pax2 activates the expression of dei in the cap cell but is unable to do so in the scolopale cell where Pros is co-expressed. We further show that D-Pax2 and Pros exert their effects on dei transcription via a 262 bp chordotonal-specific enhancer in which two D-Pax2- and three Pros-binding sites were identified experimentally. When this enhancer was removed from the fly genome, the cap- and ligament-specific expression of dei was lost, resulting in loss of chordotonal organ functionality and defective larval locomotion. Thus, coordinated larval locomotion depends on the activity of a dei enhancer that integrates both activating and repressive inputs for the generation of a functional proprioceptive organ.
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Affiliation(s)
- Adel Avetisyan
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yael Glatt
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Maya Cohen
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yael Timerman
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Nitay Aspis
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Atalya Nachman
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Naomi Halachmi
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Ella Preger-Ben Noon
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
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11
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Li Q, Jang H, Lim KY, Lessing A, Stavropoulos N. insomniac links the development and function of a sleep-regulatory circuit. eLife 2021; 10:65437. [PMID: 34908527 PMCID: PMC8758140 DOI: 10.7554/elife.65437] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 10/15/2021] [Indexed: 11/17/2022] Open
Abstract
Although many genes are known to influence sleep, when and how they impact sleep-regulatory circuits remain ill-defined. Here, we show that insomniac (inc), a conserved adaptor for the autism-associated Cul3 ubiquitin ligase, acts in a restricted period of neuronal development to impact sleep in adult Drosophila. The loss of inc causes structural and functional alterations within the mushroom body (MB), a center for sensory integration, associative learning, and sleep regulation. In inc mutants, MB neurons are produced in excess, develop anatomical defects that impede circuit assembly, and are unable to promote sleep when activated in adulthood. Our findings link neurogenesis and postmitotic development of sleep-regulatory neurons to their adult function and suggest that developmental perturbations of circuits that couple sensory inputs and sleep may underlie sleep dysfunction in neurodevelopmental disorders.
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Affiliation(s)
- Qiuling Li
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
| | - Hyunsoo Jang
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
| | - Kayla Y Lim
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
| | - Alexie Lessing
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
| | - Nicholas Stavropoulos
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
- Waksman Institute, Rutgers UniversityPiscatawayUnited 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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Aiello G, Ballabio C, Ruggeri R, Fagnocchi L, Anderle M, Morassut I, Caron D, Garilli F, Gianno F, Giangaspero F, Piazza S, Romanel A, Zippo A, Tiberi L. Truncated BRPF1 Cooperates with Smoothened to Promote Adult Shh Medulloblastoma. Cell Rep 2020; 29:4036-4052.e10. [PMID: 31851932 DOI: 10.1016/j.celrep.2019.11.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 05/14/2019] [Accepted: 11/12/2019] [Indexed: 12/12/2022] Open
Abstract
The transition of neural progenitors to differentiated postmitotic neurons is mainly considered irreversible in physiological conditions. In the present work, we show that Shh pathway activation through SmoM2 expression promotes postmitotic neurons dedifferentiation, re-entering in the cell cycle and originating medulloblastoma in vivo. Notably, human adult patients present inactivating mutations of the chromatin reader BRPF1 that are associated with SMO mutations and absent in pediatric and adolescent patients. Here, we found that truncated BRPF1 protein, as found in human adult patients, is able to induce medulloblastoma in adult mice upon SmoM2 activation. Indeed, postmitotic neurons re-entered the cell cycle and proliferated as a result of chromatin remodeling of neurons by BRPF1. Our model of brain cancer explains the onset of a subset of human medulloblastoma in adult individuals where granule neuron progenitors are no longer present.
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Affiliation(s)
- Giuseppe Aiello
- Armenise-Harvard Laboratory of Brain Disorders and Cancer, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Claudio Ballabio
- Armenise-Harvard Laboratory of Brain Disorders and Cancer, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Riccardo Ruggeri
- Armenise-Harvard Laboratory of Brain Disorders and Cancer, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Luca Fagnocchi
- Laboratory of Chromatin Biology & Epigenetics, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Marica Anderle
- Armenise-Harvard Laboratory of Brain Disorders and Cancer, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Ilaria Morassut
- Armenise-Harvard Laboratory of Brain Disorders and Cancer, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Davide Caron
- Armenise-Harvard Laboratory of Brain Disorders and Cancer, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Francesca Garilli
- Armenise-Harvard Laboratory of Brain Disorders and Cancer, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Francesca Gianno
- Department of Radiologic, Oncologic and Anatomo Pathological Sciences, University Sapienza of Rome, Rome, Italy; IRCCS Neuromed, Pozzilli, Isernia, Italy
| | - Felice Giangaspero
- Department of Radiologic, Oncologic and Anatomo Pathological Sciences, University Sapienza of Rome, Rome, Italy; IRCCS Neuromed, Pozzilli, Isernia, Italy
| | - Silvano Piazza
- Bioinformatics Core Facility, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Alessandro Romanel
- Laboratory of Bioinformatics and Computational Genomics, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Alessio Zippo
- Laboratory of Chromatin Biology & Epigenetics, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy
| | - Luca Tiberi
- Armenise-Harvard Laboratory of Brain Disorders and Cancer, CIBIO, University of Trento, Via Sommarive 9, 38123 Trento, Italy.
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14
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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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15
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Bravo González‐Blas C, Quan X, Duran‐Romaña R, Taskiran II, Koldere D, Davie K, Christiaens V, Makhzami S, Hulselmans G, de Waegeneer M, Mauduit D, Poovathingal S, Aibar S, Aerts S. Identification of genomic enhancers through spatial integration of single-cell transcriptomics and epigenomics. Mol Syst Biol 2020; 16:e9438. [PMID: 32431014 PMCID: PMC7237818 DOI: 10.15252/msb.20209438] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 01/02/2023] Open
Abstract
Single-cell technologies allow measuring chromatin accessibility and gene expression in each cell, but jointly utilizing both layers to map bona fide gene regulatory networks and enhancers remains challenging. Here, we generate independent single-cell RNA-seq and single-cell ATAC-seq atlases of the Drosophila eye-antennal disc and spatially integrate the data into a virtual latent space that mimics the organization of the 2D tissue using ScoMAP (Single-Cell Omics Mapping into spatial Axes using Pseudotime ordering). To validate spatially predicted enhancers, we use a large collection of enhancer-reporter lines and identify ~ 85% of enhancers in which chromatin accessibility and enhancer activity are coupled. Next, we infer enhancer-to-gene relationships in the virtual space, finding that genes are mostly regulated by multiple, often redundant, enhancers. Exploiting cell type-specific enhancers, we deconvolute cell type-specific effects of bulk-derived chromatin accessibility QTLs. Finally, we discover that Prospero drives neuronal differentiation through the binding of a GGG motif. In summary, we provide a comprehensive spatial characterization of gene regulation in a 2D tissue.
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Affiliation(s)
| | - Xiao‐Jiang Quan
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
| | | | - Ibrahim Ihsan Taskiran
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
| | - Duygu Koldere
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
| | | | - Valerie Christiaens
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
| | - Samira Makhzami
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
| | - Gert Hulselmans
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
| | - Maxime de Waegeneer
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
| | - David Mauduit
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
| | | | - Sara Aibar
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
| | - Stein Aerts
- VIB Center for Brain & Disease ResearchLeuvenBelgium
- Department of Human GeneticsKU LeuvenLeuvenBelgium
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16
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Hassan A, Araguas Rodriguez P, Heidmann SK, Walmsley EL, Aughey GN, Southall TD. Condensin I subunit Cap-G is essential for proper gene expression during the maturation of post-mitotic neurons. eLife 2020; 9:e55159. [PMID: 32255428 PMCID: PMC7170655 DOI: 10.7554/elife.55159] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 04/06/2020] [Indexed: 02/07/2023] Open
Abstract
Condensin complexes are essential for mitotic chromosome assembly and segregation during cell divisions, however, little is known about their functions in post-mitotic cells. Here we report a role for the condensin I subunit Cap-G in Drosophila neurons. We show that, despite not requiring condensin for mitotic chromosome compaction, post-mitotic neurons express Cap-G. Knockdown of Cap-G specifically in neurons (from their birth onwards) results in developmental arrest, behavioural defects, and dramatic gene expression changes, including reduced expression of a subset of neuronal genes and aberrant expression of genes that are not normally expressed in the developing brain. Knockdown of Cap-G in mature neurons results in similar phenotypes but to a lesser degree. Furthermore, we see dynamic binding of Cap-G at distinct loci in progenitor cells and differentiated neurons. Therefore, Cap-G is essential for proper gene expression in neurons and plays an important role during the early stages of neuronal development.
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Affiliation(s)
- Amira Hassan
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | | | | | - Emma L Walmsley
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - Gabriel N Aughey
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - Tony D Southall
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
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17
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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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18
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Hao X, Wang S, Lu Y, Yu W, Li P, Jiang D, Guo T, Li M, Li J, Xu J, Wu W, Ho MS, Zhang L. Lola regulates Drosophila adult midgut homeostasis via non-canonical hippo signaling. eLife 2020; 9:47542. [PMID: 31934851 PMCID: PMC7299341 DOI: 10.7554/elife.47542] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 01/10/2020] [Indexed: 01/12/2023] Open
Abstract
Tissue homeostasis and regeneration in the Drosophila midgut is regulated by a diverse array of signaling pathways including the Hippo pathway. Hippo signaling restricts intestinal stem cell (ISC) proliferation by sequestering the transcription co-factor Yorkie (Yki) in the cytoplasm, a factor required for rapid ISC proliferation under injury-induced regeneration. Nonetheless, the mechanism of Hippo-mediated midgut homeostasis and whether canonical Hippo signaling is involved in ISC basal proliferation are less characterized. Here we identify Lola as a transcription factor acting downstream of Hippo signaling to restrict ISC proliferation in a Yki-independent manner. Not only that Lola interacts with and is stabilized by the Hippo signaling core kinase Warts (Wts), Lola rescues the enhanced ISC proliferation upon Wts depletion via suppressing Dref and SkpA expressions. Our findings reveal that Lola is a non-canonical Hippo signaling component in regulating midgut homeostasis, providing insights on the mechanism of tissue maintenance and intestinal function.
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Affiliation(s)
- Xue Hao
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Shimin Wang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Yi Lu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Wentao Yu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Pengyue Li
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Dan Jiang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Tong Guo
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Mengjie Li
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, The Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai, China
| | - Jinhui Li
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Jinjin Xu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Wenqing Wu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Margaret S Ho
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Lei Zhang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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19
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Sato K, Goto J, Yamamoto D. Sex Mysteries of the Fly Courtship Master Regulator Fruitless. Front Behav Neurosci 2019; 13:245. [PMID: 31680899 PMCID: PMC6813181 DOI: 10.3389/fnbeh.2019.00245] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/07/2019] [Indexed: 01/21/2023] Open
Abstract
The fruitless (fru) gene of Drosophila melanogaster generates two groups of protein products, the male-specific FruM proteins and non-sex-specific FruCOM proteins. The FruM proteins have a 101 amino acids (a.a.)-long extension at the N-terminus which is absent from FruCOM. We suggest that this N-terminal extension might confer male-specific roles on FruM interaction partner proteins such as Lola, which otherwise operates as a transcription factor common to both sexes. FruM-expressing neurons are known to connect with other neurons to form a sexually dimorphic circuit for male mating behavior. We propose that FruM proteins expressed in two synaptic partners specify, at the transcriptional level, signaling pathways through which select pre- and post-synaptic partners communicate, and thereby pleiotropic ligand-receptor pairs for cell-cell interactions acquire the high specificity for mutual connections between two FruM-positive cells. We further discuss the possibility that synaptic connections made by FruM-positive neurons are regulated by neural activities, which in turn upregulate Fru expression in active cells, resulting in feedforward enhancement of courtship activities of the male fly.
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Affiliation(s)
- Kosei Sato
- Neuro-Network Evolution Project, Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe, Japan
| | - Junpei Goto
- Division of Neurogenetics, Tohoku University Graduate School of Life Sciences, Sendai, Japan
| | - Daisuke Yamamoto
- Neuro-Network Evolution Project, Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe, Japan
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20
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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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21
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Tikhonov M, Utkina M, Maksimenko O, Georgiev P. Conserved sequences in the Drosophila mod(mdg4) intron promote poly(A)-independent transcription termination and trans-splicing. Nucleic Acids Res 2019; 46:10608-10618. [PMID: 30102331 PMCID: PMC6237743 DOI: 10.1093/nar/gky716] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 07/26/2018] [Indexed: 11/15/2022] Open
Abstract
Alternative splicing (AS) is a regulatory mechanism of gene expression that greatly expands the coding capacities of genomes by allowing the generation of multiple mRNAs from a single gene. In Drosophila, the mod(mdg4) locus is an extreme example of AS that produces more than 30 different mRNAs via trans-splicing that joins together the common exons and the 3′ variable exons generated from alternative promoters. To map the regions required for trans-splicing, we have developed an assay for measuring trans-splicing events and identified a 73-bp region in the last common intron that is critical for trans-splicing of three pre-mRNAs synthesized from different DNA strands. We have also found that conserved sequences in the distal part of the last common intron induce polyadenylation-independent transcription termination and are enriched by paused RNA polymerase II (RNAP II). These results suggest that all mod(mdg4) mRNAs are formed by joining in trans the 5′ splice site in the last common exon with the 3′ splice site in one of the alternative exons.
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Affiliation(s)
- Maxim Tikhonov
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Marina Utkina
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Oksana Maksimenko
- Group of Molecular Organization of Genome, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
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22
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Froldi F, Pachnis P, Szuperák M, Costas O, Fernando T, Gould AP, Cheng LY. Histidine is selectively required for the growth of Myc-dependent dedifferentiation tumours in the Drosophila CNS. EMBO J 2019; 38:embj.201899895. [PMID: 30804004 PMCID: PMC6443203 DOI: 10.15252/embj.201899895] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 01/09/2019] [Accepted: 01/16/2019] [Indexed: 12/31/2022] Open
Abstract
Rewired metabolism of glutamine in cancer has been well documented, but less is known about other amino acids such as histidine. Here, we use Drosophila cancer models to show that decreasing the concentration of histidine in the diet strongly inhibits the growth of mutant clones induced by loss of Nerfin‐1 or gain of Notch activity. In contrast, changes in dietary histidine have much less effect on the growth of wildtype neural stem cells and Prospero neural tumours. The reliance of tumours on dietary histidine and also on histidine decarboxylase (Hdc) depends upon their growth requirement for Myc. We demonstrate that Myc overexpression in nerfin‐1 tumours is sufficient to switch their mode of growth from histidine/Hdc sensitive to resistant. This study suggests that perturbations in histidine metabolism selectively target neural tumours that grow via a dedifferentiation process involving large cell size increases driven by Myc.
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Affiliation(s)
- Francesca Froldi
- Peter MacCallum Cancer Centre, Parkville, Vic., Australia.,Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Vic., Australia
| | | | - Milán Szuperák
- Peter MacCallum Cancer Centre, Parkville, Vic., Australia.,Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Olivia Costas
- Peter MacCallum Cancer Centre, Parkville, Vic., Australia.,Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Vic., Australia
| | | | | | - Louise Y Cheng
- Peter MacCallum Cancer Centre, Parkville, Vic., Australia .,Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Vic., Australia.,The Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Vic., Australia
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23
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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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24
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The Scalloped and Nerfin-1 Transcription Factors Cooperate to Maintain Neuronal Cell Fate. Cell Rep 2018; 25:1561-1576.e7. [DOI: 10.1016/j.celrep.2018.10.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/14/2018] [Accepted: 10/09/2018] [Indexed: 02/08/2023] Open
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25
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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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26
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Dinges N, Morin V, Kreim N, Southall TD, Roignant JY. Comprehensive Characterization of the Complex lola Locus Reveals a Novel Role in the Octopaminergic Pathway via Tyramine Beta-Hydroxylase Regulation. Cell Rep 2018; 21:2911-2925. [PMID: 29212035 DOI: 10.1016/j.celrep.2017.11.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 09/12/2017] [Accepted: 11/02/2017] [Indexed: 10/18/2022] Open
Abstract
Longitudinals lacking (lola) is one of the most complex genes in Drosophila melanogaster, encoding up to 20 protein isoforms that include key transcription factors involved in axonal pathfinding and neural reprogramming. Most previous studies have employed loss-of-function alleles that disrupt lola common exons, making it difficult to delineate isoform-specific functions. To overcome this issue, we have generated isoform-specific mutants for all isoforms using CRISPR/Cas9. This enabled us to study specific isoforms with respect to previously characterized roles for Lola and to demonstrate a specific function for one variant in axon guidance via activation of the microtubule-associated factor Futsch. Importantly, we also reveal a role for a second variant in preventing neurodegeneration via the positive regulation of a key enzyme of the octopaminergic pathway. Thus, our comprehensive study expands the functional repertoire of Lola functions, and it adds insights into the regulatory control of neurotransmitter expression in vivo.
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Affiliation(s)
- Nadja Dinges
- Laboratory of RNA Epigenetics, Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Violeta Morin
- Laboratory of RNA Epigenetics, Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Nastasja Kreim
- Bioinformatics Core Facility, Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Tony D Southall
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, London SW7 2AZ, UK
| | - Jean-Yves Roignant
- Laboratory of RNA Epigenetics, Institute of Molecular Biology (IMB), 55128 Mainz, Germany.
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27
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Mora N, Oliva C, Fiers M, Ejsmont R, Soldano A, Zhang TT, Yan J, Claeys A, De Geest N, Hassan BA. A Temporal Transcriptional Switch Governs Stem Cell Division, Neuronal Numbers, and Maintenance of Differentiation. Dev Cell 2018; 45:53-66.e5. [DOI: 10.1016/j.devcel.2018.02.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 02/12/2018] [Accepted: 02/26/2018] [Indexed: 01/06/2023]
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28
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Torres J, Monti R, Moore AL, Seimiya M, Jiang Y, Beerenwinkel N, Beisel C, Beira JV, Paro R. A switch in transcription and cell fate governs the onset of an epigenetically-deregulated tumor in Drosophila. eLife 2018; 7:32697. [PMID: 29560857 PMCID: PMC5862528 DOI: 10.7554/elife.32697] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 03/04/2018] [Indexed: 12/20/2022] Open
Abstract
Tumor initiation is often linked to a loss of cellular identity. Transcriptional programs determining cellular identity are preserved by epigenetically-acting chromatin factors. Although such regulators are among the most frequently mutated genes in cancer, it is not well understood how an abnormal epigenetic condition contributes to tumor onset. In this work, we investigated the gene signature of tumors caused by disruption of the Drosophila epigenetic regulator, polyhomeotic (ph). In larval tissue ph mutant cells show a shift towards an embryonic-like signature. Using loss- and gain-of-function experiments we uncovered the embryonic transcription factor knirps (kni) as a new oncogene. The oncogenic potential of kni lies in its ability to activate JAK/STAT signaling and block differentiation. Conversely, tumor growth in ph mutant cells can be substantially reduced by overexpressing a differentiation factor. This demonstrates that epigenetically derailed tumor conditions can be reversed when targeting key players in the transcriptional network. When an animal is developing as an embryo, different cells start to specialize into the specific cell types needed to form the tissues and organs of the body. How an individual cell commits to become a certain type of cell is mostly determined by which of the genes in its DNA are active. In animal cells, DNA is wrapped around proteins called histones, and one way that cells can maintain their distinct pattern of gene activity is via chemical tags on the histones. These tags can switch nearby genes on or off, and are added or removed by other proteins called epigenetic regulators. The epigenetic tags are also stably inherited when the cell divides, meaning that a cell’s identity can be maintained over many cell generations. If epigenetic regulators fail to work properly or get disrupted, the pattern of gene activity in a cell becomes altered. As a consequence, that cell can lose its identity and will often turn into a cancer cell. In fact, mutations in epigenetic regulators are found in several human cancers. It is not yet understood how these changes in gene expression lead cells to become cancerous. Torres et al. have now analyzed an epigenetic regulator called Polyhomeotic in developing larvae of the fruit fly, Drosophila melanogaster. The results show that when Polyhomeotic is not produced the fly larvae develop tumors. Moreover, the mutant cells without Polyhomeotic had different gene expression profiles compared to normal cells. This in turn caused the mutant cells, which had previously committed to a certain fate, to become more like the unspecialized cells found in early embryos. Torres et al. next showed that, among the genes that were incorrectly regulated when Polyhomeotic’s activity was compromised, one gene called knirps was switched on by mistake, which led the mutant cells to become tumor cells. When the activity of knirps was reduced instead, almost no tumors grew. Additionally, Torres et al. found that the protein encoded by knirps activates a signaling pathway that keeps tumor cells unspecialized by blocking their normal progress to a more mature and specialized state – a process known as differentiation. Experimentally raising the levels of a different molecule that ultimately promotes differentiation caused the tumor cells to grow less. These findings suggest that tumors caused when epigenetic regulation goes awry may be reversed by targeting key genes such as knirps. Further work is now needed to test whether these findings will also extend to humans. Forcing cancer cells from a highly dividing, non-specialized state into a dead-end, mature state may lead to new ways to treat cancer.
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Affiliation(s)
- Joana Torres
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Remo Monti
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Ariane L Moore
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland.,Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Makiko Seimiya
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Yanrui Jiang
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Niko Beerenwinkel
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland.,Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Christian Beisel
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Jorge V Beira
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Renato Paro
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland.,Faculty of Science, University of Basel, Basel, Switzerland
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29
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Aughey GN, Estacio Gomez A, Thomson J, Yin H, Southall TD. CATaDa reveals global remodelling of chromatin accessibility during stem cell differentiation in vivo. eLife 2018; 7:32341. [PMID: 29481322 PMCID: PMC5826290 DOI: 10.7554/elife.32341] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 01/30/2018] [Indexed: 01/09/2023] Open
Abstract
During development eukaryotic gene expression is coordinated by dynamic changes in chromatin structure. Measurements of accessible chromatin are used extensively to identify genomic regulatory elements. Whilst chromatin landscapes of pluripotent stem cells are well characterised, chromatin accessibility changes in the development of somatic lineages are not well defined. Here we show that cell-specific chromatin accessibility data can be produced via ectopic expression of E. coli Dam methylase in vivo, without the requirement for cell-sorting (CATaDa). We have profiled chromatin accessibility in individual cell-types of Drosophila neural and midgut lineages. Functional cell-type-specific enhancers were identified, as well as novel motifs enriched at different stages of development. Finally, we show global changes in the accessibility of chromatin between stem-cells and their differentiated progeny. Our results demonstrate the dynamic nature of chromatin accessibility in somatic tissues during stem cell differentiation and provide a novel approach to understanding gene regulatory mechanisms underlying development. For an embryo to successfully develop into an adult animal, specific genes must act in different types of cells. Though all the cells have the same genes encoded within their DNA, looking at the way that the DNA is packaged can indicate which parts of the DNA are important for that particular cell type. If regions of DNA are “open” one can infer that those regions are actively involved in gene regulation, whereas “closed” regions are considered less important. It is currently difficult to determine which parts of the DNA are open within an individual cell type in a complex organ, such as the brain. Existing methods require the cells to be physically isolated from the tissue, which is technically challenging. To overcome this issue, Aughey et al. have now developed a method that does not require isolation of the cells. The new technique involves using genetic engineering to introduce an enzyme called Dam into specific cell types in living fruit flies. This enzyme adds a chemical label on regions of open DNA, which can then be detected. Aughey et al. tested this technique on various cells of the developing brain and gut, and were able to see differences in the openness of DNA that corresponded to the action of genes that are important in each cell type. The data also contain trends that help to understand the role of open DNA in development. For example, mature cells were shown to overall have less open DNA than the stem cells that divide to generate them. Aughey et al. hope their new technique will be of use to other researchers working with either fruit flies or mammalian tissues. The knowledge that scientists will gain from identifying how open DNA contributes to gene regulation, in both healthy and diseased tissues, will further our understanding of human development and the biology of diseases such as cancer.
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Affiliation(s)
- Gabriel N Aughey
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Jamie Thomson
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Hang Yin
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Tony D Southall
- Department of Life Sciences, Imperial College London, London, United Kingdom
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30
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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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31
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Silva D, Olsen KW, Bednarz MN, Droste A, Lenkeit CP, Chaharbakhshi E, Temple-Wood ER, Jemc JC. Regulation of Gonad Morphogenesis in Drosophila melanogaster by BTB Family Transcription Factors. PLoS One 2016; 11:e0167283. [PMID: 27898696 PMCID: PMC5127561 DOI: 10.1371/journal.pone.0167283] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 11/07/2016] [Indexed: 02/06/2023] Open
Abstract
During embryogenesis, primordial germ cells (PGCs) and somatic gonadal precursor cells (SGPs) migrate and coalesce to form the early gonad. A failure of the PGCs and SGPs to form a gonad with the proper architecture not only affects germ cell development, but can also lead to infertility. Therefore, it is critical to identify the molecular mechanisms that function within both the PGCs and SGPs to promote gonad morphogenesis. We have characterized the phenotypes of two genes, longitudinals lacking (lola) and ribbon (rib), that are required for the coalescence and compaction of the embryonic gonad in Drosophila melanogaster. rib and lola are expressed in the SGPs of the developing gonad, and genetic interaction analysis suggests these proteins cooperate to regulate gonad development. Both genes encode proteins with DNA binding motifs and a conserved protein-protein interaction domain, known as the Broad complex, Tramtrack, Bric-à-brac (BTB) domain. Through molecular modeling and yeast-two hybrid studies, we demonstrate that Rib and Lola homo- and heterodimerize via their BTB domains. In addition, analysis of the colocalization of Rib and Lola with marks of transcriptional activation and repression on polytene chromosomes reveals that Rib and Lola colocalize with both repressive and activating marks and with each other. While previous studies have identified Rib and Lola targets in other tissues, we find that Rib and Lola are likely to function via different downstream targets in the gonad. These results suggest that Rib and Lola act as dual-function transcription factors to cooperatively regulate embryonic gonad morphogenesis.
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Affiliation(s)
- Diane Silva
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Kenneth W. Olsen
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, United States of America
| | - Magdalena N. Bednarz
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Andrew Droste
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | | | - Edwin Chaharbakhshi
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Emily R. Temple-Wood
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Jennifer C. Jemc
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
- * E-mail:
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32
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cGMP-Dependent Protein Kinase Encoded by foraging Regulates Motor Axon Guidance in Drosophila by Suppressing Lola Function. J Neurosci 2016; 36:4635-46. [PMID: 27098704 DOI: 10.1523/jneurosci.3726-15.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Accepted: 03/21/2016] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED Correct pathfinding and target recognition of a developing axon are exquisitely regulated processes that require multiple guidance factors. Among these factors, the second messengers, cAMP and cGMP, are known to be involved in establishing the guidance cues for axon growth through different intracellular signaling pathways. However, whether and how cGMP-dependent protein kinase (PKG) regulates axon guidance remains poorly understood. Here, we show that the motor axons of intersegmental nerve b (ISNb) in the Drosophila embryo display targeting defects during axon development in the absence of foraging(for), a gene encoding PKG.In vivo tag expression revealed PKG to be present in the ventral nerve code at late embryonic stages, supporting its function in embryonic axon guidance. Mechanistic studies showed that the transcription factor longitudinal lacking(lola) genetically interacts with for.PKG physically associates with the LolaT isoform via the C-terminal zinc-finger-containing domain. Overexpression of PKG leads to the cytoplasmic retention of LolaT in S2 cells, suggesting a role for PKG in mediating the nucleocytoplasmic trafficking of Lola. Together, these findings reveal a novel function of PKG in regulating the establishment of neuronal connectivity by sequestering Lola in the cytoplasm. SIGNIFICANCE STATEMENT Axon pathfinding and target recognition are important processes in the formation of specific neuronal connectivity, which rely upon precise coordinated deployment of multiple guidance factors. This paper reveals the role of cGMP-dependent protein kinase (PKG) in regulating the pathfinding and targeting of the developing axons in Drosophila Moreover, our study indicates that PKG regulates the cytoplasmic-nuclear trafficking of the transcription factor LolaT, suggesting a mechanism of PKG in directing motor axon guidance. These findings highlight a new function of PKG in axon guidance by suppressing a transcription factor.
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33
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Chaharbakhshi E, Jemc JC. Broad-complex, tramtrack, and bric-à-brac (BTB) proteins: Critical regulators of development. Genesis 2016; 54:505-518. [DOI: 10.1002/dvg.22964] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/08/2016] [Accepted: 08/11/2016] [Indexed: 01/21/2023]
Affiliation(s)
- Edwin Chaharbakhshi
- Department of Biology; Loyola University Chicago; Chicago IL
- Stritch School of Medicine; Loyola University Chicago; Maywood IL
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34
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Wissel S, Kieser A, Yasugi T, Duchek P, Roitinger E, Gokcezade J, Steinmann V, Gaul U, Mechtler K, Förstemann K, Knoblich JA, Neumüller RA. A Combination of CRISPR/Cas9 and Standardized RNAi as a Versatile Platform for the Characterization of Gene Function. G3 (BETHESDA, MD.) 2016; 6:2467-78. [PMID: 27280787 PMCID: PMC4978900 DOI: 10.1534/g3.116.028571] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/31/2016] [Indexed: 12/21/2022]
Abstract
Traditional loss-of-function studies in Drosophila suffer from a number of shortcomings, including off-target effects in the case of RNA interference (RNAi) or the stochastic nature of mosaic clonal analysis. Here, we describe minimal in vivo GFP interference (miGFPi) as a versatile strategy to characterize gene function and to conduct highly stringent, cell type-specific loss-of-function experiments in Drosophila miGFPi combines CRISPR/Cas9-mediated tagging of genes at their endogenous locus with an immunotag and an exogenous 21 nucleotide RNAi effector sequence with the use of a single reagent, highly validated RNAi line targeting this sequence. We demonstrate the utility and time effectiveness of this method by characterizing the function of the Polymerase I (Pol I)-associated transcription factor Tif-1a, and the previously uncharacterized gene MESR4, in the Drosophila female germline stem cell lineage. In addition, we show that miGFPi serves as a powerful technique to functionally characterize individual isoforms of a gene. We exemplify this aspect of miGFPi by studying isoform-specific loss-of-function phenotypes of the longitudinals lacking (lola) gene in neural stem cells. Altogether, the miGFPi strategy constitutes a generalized loss-of-function approach that is amenable to the study of the function of all genes in the genome in a stringent and highly time effective manner.
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Affiliation(s)
- Sebastian Wissel
- Institute of Molecular Biotechnology Austria, 1030 Vienna, Austria
| | - Anja Kieser
- Gene Center, Ludwig-Maximilians-University Munich, 81377, Germany
| | - Tetsuo Yasugi
- Institute of Molecular Biotechnology Austria, 1030 Vienna, Austria
| | - Peter Duchek
- Institute of Molecular Biotechnology Austria, 1030 Vienna, Austria
| | - Elisabeth Roitinger
- Institute of Molecular Biotechnology Austria, 1030 Vienna, Austria Institute of Molecular Pathology, 1030 Vienna, Austria
| | - Joseph Gokcezade
- Institute of Molecular Biotechnology Austria, 1030 Vienna, Austria
| | | | - Ulrike Gaul
- Gene Center, Ludwig-Maximilians-University Munich, 81377, Germany
| | - Karl Mechtler
- Institute of Molecular Biotechnology Austria, 1030 Vienna, Austria Institute of Molecular Pathology, 1030 Vienna, Austria
| | - Klaus Förstemann
- Gene Center, Ludwig-Maximilians-University Munich, 81377, Germany
| | | | - Ralph A Neumüller
- Institute of Molecular Biotechnology Austria, 1030 Vienna, Austria Gene Center, Ludwig-Maximilians-University Munich, 81377, Germany
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35
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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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Froldi F, Cheng LY. Understanding how differentiation is maintained: lessons from the Drosophila brain. Cell Mol Life Sci 2016; 73:1641-4. [PMID: 26817462 PMCID: PMC11108259 DOI: 10.1007/s00018-016-2144-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Revised: 01/14/2016] [Accepted: 01/18/2016] [Indexed: 12/19/2022]
Abstract
The ability to maintain cells in a differentiated state and to prevent them from reprogramming into a multipotent state has recently emerged as a central theme in neural development as well as in oncogenesis. In the developing central nervous system (CNS) of the fruit fly Drosophila, several transcription factors were recently identified to be required in postmitotic cells to maintain differentiation, and in their absence, mature neurons undergo dedifferentiation, giving rise to proliferative neural stem cells and ultimately to tumor growth. In this review, we will highlight the current understanding of dedifferentiation and cell plasticity in the Drosophila CNS.
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Affiliation(s)
- Francesca Froldi
- Peter MacCallum Cancer Centre, East Melbourne, VIC, 3002, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Louise Y Cheng
- Peter MacCallum Cancer Centre, East Melbourne, VIC, 3002, Australia.
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC, 3010, Australia.
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Liu Z, Zhong G, Chai PC, Luo L, Liu S, Yang Y, Baeg GH, Cai Y. Coordinated niche-associated signals promote germline homeostasis in the Drosophila ovary. J Cell Biol 2016; 211:469-84. [PMID: 26504174 PMCID: PMC4621830 DOI: 10.1083/jcb.201503033] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Stem cell niches provide localized signaling molecules to promote stem cell fate and to suppress differentiation. The Drosophila melanogaster ovarian niche is established by several types of stromal cells, including terminal filament cells, cap cells, and escort cells (ECs). Here, we show that, in addition to its well-known function as a niche factor expressed in cap cells, the Drosophila transforming growth factor β molecule Decapentaplegic (Dpp) is expressed at a low level in ECs to maintain a pool of partially differentiated germline cells that may dedifferentiate to replenish germline stem cells upon their depletion under normal and stress conditions. Our study further reveals that the Dpp level in ECs is modulated by Hedgehog (Hh) ligands, which originate from both cap cells and ECs. We also demonstrate that Hh signaling exerts its function by suppressing Janus kinase/signal transducer activity, which promotes Dpp expression in ECs. Collectively, our data suggest a complex interplay of niche-associated signals that controls the development of a stem cell lineage.
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Affiliation(s)
- Zhong Liu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604
| | - Guohua Zhong
- Laboratory of Insect Toxicology, South China Agriculture University, Guangzhou, PR China 510642
| | - Phing Chian Chai
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604
| | - Lichao Luo
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Sen Liu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604
| | - Ying Yang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Gyeong-Hun Baeg
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597
| | - Yu Cai
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117543
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Functional genomics identifies regulators of the phototransduction machinery in the Drosophila larval eye and adult ocelli. Dev Biol 2016; 410:164-177. [PMID: 26769100 DOI: 10.1016/j.ydbio.2015.12.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 12/22/2015] [Accepted: 12/22/2015] [Indexed: 11/21/2022]
Abstract
Sensory perception of light is mediated by specialized Photoreceptor neurons (PRs) in the eye. During development all PRs are genetically determined to express a specific Rhodopsin (Rh) gene and genes mediating a functional phototransduction pathway. While the genetic and molecular mechanisms of PR development is well described in the adult compound eye, it remains unclear how the expression of Rhodopsins and the phototransduction cascade is regulated in other visual organs in Drosophila, such as the larval eye and adult ocelli. Using transcriptome analysis of larval PR-subtypes and ocellar PRs we identify and study new regulators required during PR differentiation or necessary for the expression of specific signaling molecules of the functional phototransduction pathway. We found that the transcription factor Krüppel (Kr) is enriched in the larval eye and controls PR differentiation by promoting Rh5 and Rh6 expression. We also identified Camta, Lola, Dve and Hazy as key genes acting during ocellar PR differentiation. Further we show that these transcriptional regulators control gene expression of the phototransduction cascade in both larval eye and adult ocelli. Our results show that PR cell type-specific transcriptome profiling is a powerful tool to identify key transcriptional regulators involved during several aspects of PR development and differentiation. Our findings greatly contribute to the understanding of how combinatorial action of key transcriptional regulators control PR development and the regulation of a functional phototransduction pathway in both larval eye and adult ocelli.
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Jin Y, Ha N, Forés M, Xiang J, Gläßer C, Maldera J, Jiménez G, Edgar BA. EGFR/Ras Signaling Controls Drosophila Intestinal Stem Cell Proliferation via Capicua-Regulated Genes. PLoS Genet 2015; 11:e1005634. [PMID: 26683696 PMCID: PMC4684324 DOI: 10.1371/journal.pgen.1005634] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 10/08/2015] [Indexed: 01/19/2023] Open
Abstract
Epithelial renewal in the Drosophila intestine is orchestrated by Intestinal Stem Cells (ISCs). Following damage or stress the intestinal epithelium produces ligands that activate the epidermal growth factor receptor (EGFR) in ISCs. This promotes their growth and division and, thereby, epithelial regeneration. Here we demonstrate that the HMG-box transcriptional repressor, Capicua (Cic), mediates these functions of EGFR signaling. Depleting Cic in ISCs activated them for division, whereas overexpressed Cic inhibited ISC proliferation and midgut regeneration. Epistasis tests showed that Cic acted as an essential downstream effector of EGFR/Ras signaling, and immunofluorescence showed that Cic's nuclear localization was regulated by EGFR signaling. ISC-specific mRNA expression profiling and DNA binding mapping using DamID indicated that Cic represses cell proliferation via direct targets including string (Cdc25), Cyclin E, and the ETS domain transcription factors Ets21C and Pointed (pnt). pnt was required for ISC over-proliferation following Cic depletion, and ectopic pnt restored ISC proliferation even in the presence of overexpressed dominant-active Cic. These studies identify Cic, Pnt, and Ets21C as critical downstream effectors of EGFR signaling in Drosophila ISCs.
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Affiliation(s)
- Yinhua Jin
- Deutsches Krebsforschungszentrum (DKFZ) - Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) Allianz, Heidelberg, Germany
| | - Nati Ha
- Biochemie-Zentrum der Universität Heidelberg (BZH), Heidelberg, Germany
| | - Marta Forés
- Institut de Biologia Molecular de Barcelona-CSIC, Parc Científic de Barcelona, Barcelona, Spain
| | - Jinyi Xiang
- Deutsches Krebsforschungszentrum (DKFZ) - Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) Allianz, Heidelberg, Germany
| | - Christine Gläßer
- Deutsches Krebsforschungszentrum (DKFZ) - Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) Allianz, Heidelberg, Germany
| | - Julieta Maldera
- Deutsches Krebsforschungszentrum (DKFZ) - Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) Allianz, Heidelberg, Germany
| | - Gerardo Jiménez
- Institut de Biologia Molecular de Barcelona-CSIC, Parc Científic de Barcelona, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Bruce A. Edgar
- Deutsches Krebsforschungszentrum (DKFZ) - Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) Allianz, Heidelberg, Germany
- * E-mail:
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40
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Aughey GN, Southall TD. Dam it's good! DamID profiling of protein-DNA interactions. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 5:25-37. [PMID: 26383089 PMCID: PMC4737221 DOI: 10.1002/wdev.205] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/06/2015] [Accepted: 07/20/2015] [Indexed: 01/09/2023]
Abstract
The interaction of proteins with chromatin is fundamental for several essential cellular processes. During the development of an organism, genes must to be tightly regulated both temporally and spatially. This is achieved through the action of chromatin‐binding proteins such as transcription factors, histone modifiers, nucleosome remodelers, and lamins. Furthermore, protein–DNA interactions are important in the adult, where their perturbation can lead to disruption of homeostasis, metabolic dysregulation, and diseases such as cancer. Understanding the nature of these interactions is of paramount importance in almost all areas of molecular biological research. In recent years, DNA adenine methyltransferase identification (DamID) has emerged as one of the most comprehensive and versatile methods available for profiling protein–DNA interactions on a genomic scale. DamID has been used to map a variety of chromatin‐binding proteins in several model organisms and has the potential for continued adaptation and application in the field of genomic biology. WIREs Dev Biol 2016, 5:25–37. doi: 10.1002/wdev.205 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Gabriel N Aughey
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, London, UK
| | - Tony D Southall
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, London, UK
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McClure CD, Southall TD. Getting Down to Specifics: Profiling Gene Expression and Protein-DNA Interactions in a Cell Type-Specific Manner. ADVANCES IN GENETICS 2015; 91:103-151. [PMID: 26410031 PMCID: PMC4604662 DOI: 10.1016/bs.adgen.2015.06.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The majority of multicellular organisms are comprised of an extraordinary range of cell types, with different properties and gene expression profiles. Understanding what makes each cell type unique and how their individual characteristics are attributed are key questions for both developmental and neurobiologists alike. The brain is an excellent example of the cellular diversity expressed in the majority of eukaryotes. The mouse brain comprises of approximately 75 million neurons varying in morphology, electrophysiology, and preferences for synaptic partners. A powerful process in beginning to pick apart the mechanisms that specify individual characteristics of the cell, as well as their fate, is to profile gene expression patterns, chromatin states, and transcriptional networks in a cell type-specific manner, i.e., only profiling the cells of interest in a particular tissue. Depending on the organism, the questions being investigated, and the material available, certain cell type-specific profiling methods are more suitable than others. This chapter reviews the approaches presently available for selecting and isolating specific cell types and evaluates their key features.
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Affiliation(s)
- Colin D. McClure
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Tony D. Southall
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, South Kensington Campus, London SW7 2AZ, United Kingdom
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42
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Gao JL, Fan YJ, Wang XY, Zhang Y, Pu J, Li L, Shao W, Zhan S, Hao J, Xu YZ. A conserved intronic U1 snRNP-binding sequence promotes trans-splicing in Drosophila. Genes Dev 2015; 29:760-71. [PMID: 25838544 PMCID: PMC4387717 DOI: 10.1101/gad.258863.115] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Gao et al. investigate mod(mdg4), a classic trans-spliced gene in Drosophila, and report that two critical RNA sequences in the middle of the last 5′ intron, TSA and TSB, promote trans-splicing of mod(mdg4). In TSA, a 13-nt core motif is conserved across Drosophila species and is essential and sufficient for trans-splicing, which binds U1 snRNP through strong base-pairing with U1 snRNA. In TSB, a conserved secondary structure acts as an enhancer. Deletions of TSA and TSB result in developmental defects in flies. Unlike typical cis-splicing, trans-splicing joins exons from two separate transcripts to produce chimeric mRNA and has been detected in most eukaryotes. Trans-splicing in trypanosomes and nematodes has been characterized as a spliced leader RNA-facilitated reaction; in contrast, its mechanism in higher eukaryotes remains unclear. Here we investigate mod(mdg4), a classic trans-spliced gene in Drosophila, and report that two critical RNA sequences in the middle of the last 5′ intron, TSA and TSB, promote trans-splicing of mod(mdg4). In TSA, a 13-nucleotide (nt) core motif is conserved across Drosophila species and is essential and sufficient for trans-splicing, which binds U1 small nuclear RNP (snRNP) through strong base-pairing with U1 snRNA. In TSB, a conserved secondary structure acts as an enhancer. Deletions of TSA and TSB using the CRISPR/Cas9 system result in developmental defects in flies. Although it is not clear how the 5′ intron finds the 3′ introns, compensatory changes in U1 snRNA rescue trans-splicing of TSA mutants, demonstrating that U1 recruitment is critical to promote trans-splicing in vivo. Furthermore, TSA core-like motifs are found in many other trans-spliced Drosophila genes, including lola. These findings represent a novel mechanism of trans-splicing, in which RNA motifs in the 5′ intron are sufficient to bring separate transcripts into close proximity to promote trans-splicing.
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Affiliation(s)
- Jun-Li Gao
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yu-Jie Fan
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Xiu-Ye Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yu Zhang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jia Pu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Liang Li
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Wei Shao
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Shuai Zhan
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | | | - Yong-Zhen Xu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
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Janesick A, Wu SC, Blumberg B. Retinoic acid signaling and neuronal differentiation. Cell Mol Life Sci 2015; 72:1559-76. [PMID: 25558812 PMCID: PMC11113123 DOI: 10.1007/s00018-014-1815-9] [Citation(s) in RCA: 188] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 12/15/2014] [Accepted: 12/19/2014] [Indexed: 01/13/2023]
Abstract
The identification of neurological symptoms caused by vitamin A deficiency pointed to a critical, early developmental role of vitamin A and its metabolite, retinoic acid (RA). The ability of RA to induce post-mitotic, neural phenotypes in various stem cells, in vitro, served as early evidence that RA is involved in the switch between proliferation and differentiation. In vivo studies have expanded this "opposing signal" model, and the number of primary neurons an embryo develops is now known to depend critically on the levels and spatial distribution of RA. The proneural and neurogenic transcription factors that control the exit of neural progenitors from the cell cycle and allow primary neurons to develop are partly elucidated, but the downstream effectors of RA receptor (RAR) signaling (many of which are putative cell cycle regulators) remain largely unidentified. The molecular mechanisms underlying RA-induced primary neurogenesis in anamniote embryos are starting to be revealed; however, these data have been not been extended to amniote embryos. There is growing evidence that bona fide RARs are found in some mollusks and other invertebrates, but little is known about their necessity or functions in neurogenesis. One normal function of RA is to regulate the cell cycle to halt proliferation, and loss of RA signaling is associated with dedifferentiation and the development of cancer. Identifying the genes and pathways that mediate cell cycle exit downstream of RA will be critical for our understanding of how to target tumor differentiation. Overall, elucidating the molecular details of RAR-regulated neurogenesis will be decisive for developing and understanding neural proliferation-differentiation switches throughout development.
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Affiliation(s)
- Amanda Janesick
- Department of Developmental and Cell Biology, 2011 Biological Sciences 3, University of California, Irvine, 92697-2300 USA
| | - Stephanie Cherie Wu
- Department of Developmental and Cell Biology, 2011 Biological Sciences 3, University of California, Irvine, 92697-2300 USA
| | - Bruce Blumberg
- Department of Developmental and Cell Biology, 2011 Biological Sciences 3, University of California, Irvine, 92697-2300 USA
- Department of Pharmaceutical Sciences, University of California, Irvine, USA
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Froldi F, Szuperak M, Weng CF, Shi W, Papenfuss AT, Cheng LY. The transcription factor Nerfin-1 prevents reversion of neurons into neural stem cells. Genes Dev 2015; 29:129-43. [PMID: 25593306 PMCID: PMC4298133 DOI: 10.1101/gad.250282.114] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Froldi et al. show that the Drosophila zinc finger transcription factor Nervous fingers 1 (Nerfin-1) locks neurons into differentiation, preventing their reversion into neuroblasts. The loss of Nerfin-1 causes reversion to multipotency and results in tumors in several neural lineages. RNA-seq and ChIP analysis show that Nerfin-1 administers its function by repression of self-renewing genes and activation of differentiation-specific genes. Cellular dedifferentiation is the regression of a cell from a specialized state to a more multipotent state and is implicated in cancer. However, the transcriptional network that prevents differentiated cells from reacquiring stem cell fate is so far unclear. Neuroblasts (NBs), the Drosophila neural stem cells, are a model for the regulation of stem cell self-renewal and differentiation. Here we show that the Drosophila zinc finger transcription factor Nervous fingers 1 (Nerfin-1) locks neurons into differentiation, preventing their reversion into NBs. Following Prospero-dependent neuronal specification in the ganglion mother cell (GMC), a Nerfin-1-specific transcriptional program maintains differentiation in the post-mitotic neurons. The loss of Nerfin-1 causes reversion to multipotency and results in tumors in several neural lineages. Both the onset and rate of neuronal dedifferentiation in nerfin-1 mutant lineages are dependent on Myc- and target of rapamycin (Tor)-mediated cellular growth. In addition, Nerfin-1 is required for NB differentiation at the end of neurogenesis. RNA sequencing (RNA-seq) and chromatin immunoprecipitation (ChIP) analysis show that Nerfin-1 administers its function by repression of self-renewing-specific and activation of differentiation-specific genes. Our findings support the model of bidirectional interconvertibility between neural stem cells and their post-mitotic progeny and highlight the importance of the Nerfin-1-regulated transcriptional program in neuronal maintenance.
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Affiliation(s)
- Francesca Froldi
- Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Milan Szuperak
- Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Chen-Fang Weng
- Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Wei Shi
- Bioinformatics Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Computing and Information Systems, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Anthony T Papenfuss
- Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria 3010, Australia; Bioinformatics Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Louise Y Cheng
- Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria 3010, Australia;
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Artegiani B, de Jesus Domingues AM, Bragado Alonso S, Brandl E, Massalini S, Dahl A, Calegari F. Tox: a multifunctional transcription factor and novel regulator of mammalian corticogenesis. EMBO J 2014; 34:896-910. [PMID: 25527292 DOI: 10.15252/embj.201490061] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 12/03/2014] [Indexed: 01/17/2023] Open
Abstract
Major efforts are invested to characterize the factors controlling the proliferation of neural stem cells. During mammalian corticogenesis, our group has identified a small pool of genes that are transiently downregulated in the switch of neural stem cells to neurogenic division and reinduced in newborn neurons. Among these switch genes, we found Tox, a transcription factor with hitherto uncharacterized roles in the nervous system. Here, we investigated the role of Tox in corticogenesis by characterizing its expression at the tissue, cellular and temporal level. We found that Tox is regulated by calcineurin/Nfat signalling. Moreover, we combined DNA adenine methyltransferase identification (DamID) with deep sequencing to characterize the chromatin binding properties of Tox including its motif and downstream transcriptional targets including Sox2, Tbr2, Prox1 and other key factors. Finally, we manipulated Tox in the developing brain and validated its multiple roles in promoting neural stem cell proliferation and neurite outgrowth of newborn neurons. Our data provide a valuable resource to study the role of Tox in other tissues and highlight a novel key player in brain development.
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Affiliation(s)
- Benedetta Artegiani
- DFG-Research Center for Regenerative Therapies, Cluster of Excellence, TU-Dresden, Dresden, Germany
| | | | - Sara Bragado Alonso
- DFG-Research Center for Regenerative Therapies, Cluster of Excellence, TU-Dresden, Dresden, Germany
| | - Elisabeth Brandl
- DFG-Research Center for Regenerative Therapies, Cluster of Excellence, TU-Dresden, Dresden, Germany
| | - Simone Massalini
- DFG-Research Center for Regenerative Therapies, Cluster of Excellence, TU-Dresden, Dresden, Germany
| | - Andreas Dahl
- Deep Sequencing Group-SFB655, Biotechnology Center, TU-Dresden, Dresden, Germany
| | - Federico Calegari
- DFG-Research Center for Regenerative Therapies, Cluster of Excellence, TU-Dresden, Dresden, Germany
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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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