1
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Penkert RR, LaFoya B, Moholt-Siebert L, Vargas E, Welch SE, Prehoda KE. The Drosophila neuroblast polarity cycle at a glance. J Cell Sci 2024; 137:jcs261789. [PMID: 38465513 PMCID: PMC10984279 DOI: 10.1242/jcs.261789] [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] [Indexed: 03/12/2024] Open
Abstract
Drosophila neural stem cells, or neuroblasts, rapidly proliferate during embryonic and larval development to populate the central nervous system. Neuroblasts divide asymmetrically to create cellular diversity, with each division producing one sibling cell that retains the neuroblast fate and another that differentiates into glia or neurons. This asymmetric outcome is mediated by the transient polarization of numerous factors to the cell cortex during mitosis. The powerful genetics and outstanding imaging tractability of the neuroblast make it an excellent model system for studying the mechanisms of cell polarity. This Cell Science at a Glance article and the accompanying poster explore the phases of the neuroblast polarity cycle and the regulatory circuits that control them. We discuss the key features of the cycle - the targeted recruitment of proteins to specific regions of the plasma membrane and multiple phases of highly dynamic actomyosin-dependent cortical flows that pattern both protein distribution and membrane structure.
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2
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Xu X, An H, Wu C, Sang R, Wu L, Lou Y, Yang X, Xi Y. HR repair pathway plays a crucial role in maintaining neural stem cell fate under irradiation stress. Life Sci Alliance 2023; 6:e202201802. [PMID: 37197982 PMCID: PMC10192720 DOI: 10.26508/lsa.202201802] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/19/2023] Open
Abstract
Environmental stress can cause mutation or genomic instability in stem cells which, in some cases, leads to tumorigenesis. Mechanisms to monitor and eliminate these mutant stem cells remain elusive. Here, using the Drosophila larval brain as a model, we show that X-ray irradiation (IR) at the early larval stage leads to accumulation of nuclear Prospero (Pros), resulting in premature differentiation of neural stem cells (neuroblasts, NBs). Through NB-specific RNAi screenings, we determined that it is the Mre11-Rad50-Nbs1 complex and the homologous recombination (HR) repair pathway, rather than non-homologous end-joining pathway that plays, a dominant role in the maintenance of NBs under IR stress. The DNA damage sensor ATR/mei-41 is shown to act to prevent IR-induced nuclear Pros in a WRNexo-dependent manner. The accumulation of nuclear Pros in NBs under IR stress, leads to NB cell fate termination, rather than resulting in mutant cell proliferation. Our study reveals an emerging mechanism for the HR repair pathway in maintaining neural stem cell fate under irradiation stress.
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Affiliation(s)
- Xiao Xu
- The Women's Hospital, Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Development Disorders, School of Medicine, Zhejiang University, Hangzhou, China
| | - Huanping An
- The Women's Hospital, Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Development Disorders, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Clinical Molecular Biology of Hanzhong City, Hanzhong Vocational and Technique College, Hanzhong, China
| | - Cheng Wu
- The Women's Hospital, Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Development Disorders, School of Medicine, Zhejiang University, Hangzhou, China
| | - Rong Sang
- The Women's Hospital, Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Development Disorders, School of Medicine, Zhejiang University, Hangzhou, China
| | - Litao Wu
- The Women's Hospital, Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Development Disorders, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yuhan Lou
- The Women's Hospital, Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Development Disorders, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaohang Yang
- The Women's Hospital, Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Development Disorders, School of Medicine, Zhejiang University, Hangzhou, China
- Joint Institute of Genetics and Genomic Medicine, Between Zhejiang University and University of Toronto, Zhejiang University, Hangzhou, China
| | - Yongmei Xi
- The Women's Hospital, Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Development Disorders, School of Medicine, Zhejiang University, Hangzhou, China
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3
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Salem Wehbe L, Barakat D, Acker A, El Khoury R, Reichhart JM, Matt N, El Chamy L. Protein Phosphatase 4 Negatively Regulates the Immune Deficiency-NF-κB Pathway during the Drosophila Immune Response. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2021; 207:1616-1626. [PMID: 34452932 PMCID: PMC7616922 DOI: 10.4049/jimmunol.1901497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 07/07/2021] [Indexed: 12/31/2022]
Abstract
The evolutionarily conserved immune deficiency (IMD) signaling pathway shields Drosophila against bacterial infections. It regulates the expression of antimicrobial peptides encoding genes through the activation of the NF-κB transcription factor Relish. Tight regulation of the signaling cascade ensures a balanced immune response, which is otherwise highly harmful. Several phosphorylation events mediate intracellular progression of the IMD pathway. However, signal termination by dephosphorylation remains largely elusive. Here, we identify the highly conserved protein phosphatase 4 (PP4) complex as a bona fide negative regulator of the IMD pathway. RNA interference-mediated gene silencing of PP4-19c, PP4R2, and Falafel, which encode the catalytic and regulatory subunits of the phosphatase complex, respectively, caused a marked upregulation of bacterial-induced antimicrobial peptide gene expression in both Drosophila melanogaster S2 cells and adult flies. Deregulated IMD signaling is associated with reduced lifespan of PP4-deficient flies in the absence of any infection. In contrast, flies overexpressing this phosphatase are highly sensitive to bacterial infections. Altogether, our results highlight an evolutionarily conserved function of PP4c in the regulation of NF-κB signaling from Drosophila to mammals.
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Affiliation(s)
- Layale Salem Wehbe
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and
- Unité de Recherche Environnement, Génomique et Protéomique, Faculté des Sciences, Université Saint-Joseph de Beyrouth-Liban, Mar Roukos, Mkalles, Beirut, Lebanon
| | - Dana Barakat
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and
- Unité de Recherche Environnement, Génomique et Protéomique, Faculté des Sciences, Université Saint-Joseph de Beyrouth-Liban, Mar Roukos, Mkalles, Beirut, Lebanon
| | - Adrian Acker
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and
| | - Rita El Khoury
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and
- Unité de Recherche Environnement, Génomique et Protéomique, Faculté des Sciences, Université Saint-Joseph de Beyrouth-Liban, Mar Roukos, Mkalles, Beirut, Lebanon
| | | | - Nicolas Matt
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and
| | - Laure El Chamy
- Unité de Recherche Environnement, Génomique et Protéomique, Faculté des Sciences, Université Saint-Joseph de Beyrouth-Liban, Mar Roukos, Mkalles, Beirut, Lebanon
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4
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Park J, Lee DH. Functional roles of protein phosphatase 4 in multiple aspects of cellular physiology: a friend and a foe. BMB Rep 2021. [PMID: 32192570 PMCID: PMC7196183 DOI: 10.5483/bmbrep.2020.53.4.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein phosphatase 4 (PP4), one of serine/threonine phosphatases, is involved in many critical cellular pathways, including DNA damage response (DNA repair, cell cycle regulation, and apoptosis), tumorigenesis, cell migration, immune response, stem cell development, glucose metabolism, and diabetes. PP4 has been steadily studied over the past decade about wide spectrum of physiological activities in cells. Given the many vital functions in cells, PP4 has great potential to develop into the finding of key working mechanisms and effective treatments for related diseases such as cancer and diabetes. In this review, we provide an overview of the cellular and molecular mechanisms by which PP4 impacts and also discuss the functional significance of it in cell health.
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Affiliation(s)
- Jaehong Park
- School of Biological Sciences and Biotechnology Graduate School, Chonnam National University, Gwangju 61186, Korea
| | - Dong-Hyun Lee
- Department of Biological Sciences, College of Natural Sciences, Chonnam National University, Gwangju 61186; Research Center of Ecomimetics, Chonnam National University, Gwangju 61186, Korea
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5
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Abstract
Asymmetric cell division (ACD) is an evolutionarily conserved mechanism used by prokaryotes and eukaryotes alike to control cell fate and generate cell diversity. A detailed mechanistic understanding of ACD is therefore necessary to understand cell fate decisions in health and disease. ACD can be manifested in the biased segregation of macromolecules, the differential partitioning of cell organelles, or differences in sibling cell size or shape. These events are usually preceded by and influenced by symmetry breaking events and cell polarization. In this Review, we focus predominantly on cell intrinsic mechanisms and their contribution to cell polarization, ACD and binary cell fate decisions. We discuss examples of polarized systems and detail how polarization is established and, whenever possible, how it contributes to ACD. Established and emerging model organisms will be considered alike, illuminating both well-documented and underexplored forms of polarization and ACD.
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Affiliation(s)
- Bharath Sunchu
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA
| | - Clemens Cabernard
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA
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6
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Keegan SE, Hughes SC. Role of nuclear-cytoplasmic protein localization during Drosophila neuroblast development. Genome 2020; 64:75-85. [PMID: 32526151 DOI: 10.1139/gen-2020-0039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nuclear-cytoplasmic localization is an efficient way to regulate transcription factors and chromatin remodelers. Altering the location of existing protein pools also facilitates a more rapid response to changes in cell activity or extracellular signals. There are several examples of proteins that are regulated by nucleo-cytoplasmic shuttling, which are required for Drosophila neuroblast development. Disruption of the localization of homologs of these proteins has also been linked to several neurodegenerative disorders in humans. Drosophila has been used extensively to model the neurodegenerative disorders caused by aberrant nucleo-cytoplasmic localization. Here, we focus on the role of alternative nucleo-cytoplasmic protein localization in regulating proliferation and cell fate decisions in the Drosophila neuroblast and in neurodegenerative disorders. We also explore the analogous role of RNA binding proteins and mRNA localization in the context of regulation of nucleo-cytoplasmic localization during neural development and a role in neurodegenerative disorders.
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Affiliation(s)
- Sophie E Keegan
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Sarah C Hughes
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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7
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Loyer N, Januschke J. Where does asymmetry come from? Illustrating principles of polarity and asymmetry establishment in Drosophila neuroblasts. Curr Opin Cell Biol 2020; 62:70-77. [DOI: 10.1016/j.ceb.2019.07.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 07/15/2019] [Accepted: 07/16/2019] [Indexed: 12/22/2022]
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8
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Crews ST. Drosophila Embryonic CNS Development: Neurogenesis, Gliogenesis, Cell Fate, and Differentiation. Genetics 2019; 213:1111-1144. [PMID: 31796551 PMCID: PMC6893389 DOI: 10.1534/genetics.119.300974] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 09/26/2019] [Indexed: 01/04/2023] Open
Abstract
The Drosophila embryonic central nervous system (CNS) is a complex organ consisting of ∼15,000 neurons and glia that is generated in ∼1 day of development. For the past 40 years, Drosophila developmental neuroscientists have described each step of CNS development in precise molecular genetic detail. This has led to an understanding of how an intricate nervous system emerges from a single cell. These studies have also provided important, new concepts in developmental biology, and provided an essential model for understanding similar processes in other organisms. In this article, the key genes that guide Drosophila CNS development and how they function is reviewed. Features of CNS development covered in this review are neurogenesis, gliogenesis, cell fate specification, and differentiation.
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Affiliation(s)
- Stephen T Crews
- Department of Biochemistry and Biophysics, Integrative Program for Biological and Genome Sciences, School of Medicine, The University of North Carolina at Chapel Hill, North Carolina 27599
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9
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Dong X, Zhao Y, Huang Y, Yu L, Yang X, Gao F. Analysis of long noncoding RNA expression profiles in the whole blood of neonates with hypoxic-ischemic encephalopathy. J Cell Biochem 2019; 120:8499-8509. [PMID: 30474258 DOI: 10.1002/jcb.28138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 11/05/2018] [Indexed: 01/24/2023]
Abstract
Long noncoding RNAs (lncRNAs) have been shown to participate in many biological processes. To investigate the expression profiles of lncRNAs and their potential functions in neonatal hypoxic-ischemic encephalopathy (HIE), we detected the lncRNA and messenger RNA (mRNA) expression in the peripheral blood samples from HIE patients and controls using a microarray. A total of 376 lncRNAs and 126 mRNAs were differentially expressed between the HIE and the non-HIE samples (fold change > 2). Quantitative real-time polymerase chain reaction was used to validate the microarray data. Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis were performed to determine the gene function. Furthermore, the lncRNA-mRNA coexpression network was generated to predict the potential targets of lncRNAs. In conclusion, our study first demonstrated the differential expression profiles of lncRNAs in the whole blood of infants with HIE and may provide a new view of the distinct lncRNA functions in HIE.
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Affiliation(s)
- Xiaohua Dong
- Department of Pediatric, Jingjiang People's Hospital Affiliated to Yangzhou University, Jingjiang, Jiangsu, China
| | - Yingmin Zhao
- Department of Pediatric, Jingjiang People's Hospital Affiliated to Yangzhou University, Jingjiang, Jiangsu, China
| | - Yun Huang
- Department of Pediatric, Jingjiang People's Hospital Affiliated to Yangzhou University, Jingjiang, Jiangsu, China
| | - Lingling Yu
- Department of Pediatric, Jingjiang People's Hospital Affiliated to Yangzhou University, Jingjiang, Jiangsu, China
| | - Xiaojing Yang
- Department of Pediatric, Jingjiang People's Hospital Affiliated to Yangzhou University, Jingjiang, Jiangsu, China
| | - Feng Gao
- Department of Pediatric, Jingjiang People's Hospital Affiliated to Yangzhou University, Jingjiang, Jiangsu, China
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10
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Wu D, Wu L, An H, Bao H, Guo P, Zhang B, Zheng H, Zhang F, Ge W, Cai Y, Xi Y, Yang X. RanGAP-mediated nucleocytoplasmic transport of Prospero regulates neural stem cell lifespan in Drosophila larval central brain. Aging Cell 2019; 18:e12854. [PMID: 30549175 PMCID: PMC6351831 DOI: 10.1111/acel.12854] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 06/24/2018] [Accepted: 07/30/2018] [Indexed: 11/28/2022] Open
Abstract
By the end of neurogenesis in Drosophila pupal brain neuroblasts (NBs), nuclear Prospero (Pros) triggers cell cycle exit and terminates NB lifespan. Here, we reveal that in larval brain NBs, an intrinsic mechanism facilitates import and export of Pros across the nuclear envelope via a Ran‐mediated nucleocytoplasmic transport system. In rangap mutants, the export of Pros from the nucleus to cytoplasm is impaired and the nucleocytoplasmic transport of Pros becomes one‐way traffic, causing an early accumulation of Pros in the nuclei of the larval central brain NBs. This nuclear Pros retention initiates NB cell cycle exit and leads to a premature decrease of total NB numbers. Our data indicate that RanGAP plays a crucial role in this intrinsic mechanism that controls NB lifespan during neurogenesis. Our study may provide insights into understanding the lifespan of neural stem cells during neurogenesis in other organisms.
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Affiliation(s)
- Di Wu
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Litao Wu
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Huanping An
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Hongcun Bao
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Pengfei Guo
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Bei Zhang
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- College of Life Sciences Zhejiang University Hangzhou China
| | - Huimei Zheng
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
| | - Fan Zhang
- College of Life Sciences Zhejiang University Hangzhou China
| | - Wanzhong Ge
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
| | - Yu Cai
- Temasek Life Sciences Laboratory National University of Singapore Singapore
- Department of Biological Sciences National University of Singapore Singapore
| | - Yongmei Xi
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
| | - Xiaohang Yang
- Division of Human Reproduction and Developmental Genetics The Women's Hospital School of Medicine Zhejiang University Hangzhou China
- Institute of Genetics Zhejiang University Hangzhou China
- Department of Genetics, School of Medicine Zhejiang University Hangzhou China
- Joint Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Zhejiang University Hangzhou China
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11
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Hall ET, Pradhan-Sundd T, Samnani F, Verheyen EM. The protein phosphatase 4 complex promotes the Notch pathway and wingless transcription. Biol Open 2017; 6:1165-1173. [PMID: 28652317 PMCID: PMC5576076 DOI: 10.1242/bio.025221] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The Wnt/Wingless (Wg) pathway controls cell fate specification, tissue differentiation and organ development across organisms. Using an in vivo RNAi screen to identify novel kinase and phosphatase regulators of the Wg pathway, we identified subunits of the serine threonine phosphatase Protein Phosphatase 4 (PP4). Knockdown of the catalytic and regulatory subunits of PP4 cause reductions in the Wg pathway targets Senseless and Distal-less. We find that PP4 regulates the Wg pathway by controlling Notch-driven wg transcription. Genetic interaction experiments identified that PP4 likely promotes Notch signaling within the nucleus of the Notch-receiving cell. Although the PP4 complex is implicated in various cellular processes, its role in the regulation of Wg and Notch pathways was previously uncharacterized. Our study identifies a novel role of PP4 in regulating Notch pathway, resulting in aberrations in Notch-mediated transcriptional regulation of the Wingless ligand. Furthermore, we show that PP4 regulates proliferation independent of its interaction with Notch. Summary: The protein phosphatase 4 complex promotes Notch signaling and target gene expression during Drosophila wing development.
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Affiliation(s)
- Eric T Hall
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
| | - Tirthadipa Pradhan-Sundd
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
| | - Faaria Samnani
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
| | - Esther M Verheyen
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
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12
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Ramat A, Hannaford M, Januschke J. Maintenance of Miranda Localization in Drosophila Neuroblasts Involves Interaction with the Cognate mRNA. Curr Biol 2017; 27:2101-2111.e5. [PMID: 28690114 PMCID: PMC5526833 DOI: 10.1016/j.cub.2017.06.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/01/2017] [Accepted: 06/07/2017] [Indexed: 11/28/2022]
Abstract
How cells position their proteins is a key problem in cell biology. Targeting mRNAs to distinct regions of the cytoplasm contributes to protein localization by providing local control over translation. Here, we reveal that an interdependence of a protein and cognate mRNA maintains asymmetric protein distribution in mitotic Drosophila neural stem cells. We tagged endogenous mRNA or protein products of the gene miranda that is required for fate determination with GFP. We find that the mRNA localizes like the protein it encodes in a basal crescent in mitosis. We then used GFP-specific nanobodies fused to localization domains to alter the subcellular distribution of the GFP-tagged mRNA or protein. Altering the localization of the mRNA resulted in mislocalization of the protein and vice versa. Protein localization defects caused by mislocalization of the cognate mRNA were rescued by introducing untagged mRNA coding for mutant non-localizable protein. Therefore, by combining the MS2 system and subcellular nanobody expression, we uncovered that maintenance of Mira asymmetric localization requires interaction with the cognate mRNA.
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Affiliation(s)
- Anne Ramat
- Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dow Street, DD5 1EH Dundee, UK
| | - Matthew Hannaford
- Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dow Street, DD5 1EH Dundee, UK
| | - Jens Januschke
- Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dow Street, DD5 1EH Dundee, UK.
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13
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Inscuteable maintains type I neuroblast lineage identity via Numb/Notch signaling in the Drosophila larval brain. J Genet Genomics 2017; 44:151-162. [DOI: 10.1016/j.jgg.2017.02.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 02/23/2017] [Accepted: 02/27/2017] [Indexed: 01/11/2023]
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14
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Winfree LM, Speese SD, Logan MA. Protein phosphatase 4 coordinates glial membrane recruitment and phagocytic clearance of degenerating axons in Drosophila. Cell Death Dis 2017; 8:e2623. [PMID: 28230857 PMCID: PMC5386485 DOI: 10.1038/cddis.2017.40] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 01/06/2017] [Accepted: 01/09/2017] [Indexed: 12/15/2022]
Abstract
Neuronal damage induced by injury, stroke, or neurodegenerative disease elicits swift immune responses from glial cells, including altered gene expression, directed migration to injury sites, and glial clearance of damaged neurons through phagocytic engulfment. Collectively, these responses hinder further cellular damage, but the mechanisms that underlie these important protective glial reactions are still unclear. Here, we show that the evolutionarily conserved trimeric protein phosphatase 4 (PP4) serine/threonine phosphatase complex is a novel set of factors required for proper glial responses to nerve injury in the adult Drosophila brain. Glial-specific knockdown of PP4 results in reduced recruitment of glia to severed axons and delayed glial clearance of degenerating axonal debris. We show that PP4 functions downstream of the the glial engulfment receptor Draper to drive glial morphogenesis through the guanine nucleotide exchange factor SOS and the Rho GTPase Rac1, revealing that PP4 molecularly couples Draper to Rac1-mediated cytoskeletal remodeling to ensure glial infiltration of injury sites and timely removal of damaged neurons from the CNS.
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Affiliation(s)
- Lilly M Winfree
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Sean D Speese
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Mary A Logan
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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15
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Drosophila melanogaster Neuroblasts: A Model for Asymmetric Stem Cell Divisions. Results Probl Cell Differ 2017; 61:183-210. [PMID: 28409305 DOI: 10.1007/978-3-319-53150-2_8] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Asymmetric cell division (ACD) is a fundamental mechanism to generate cell diversity, giving rise to daughter cells with different developmental potentials. ACD is manifested in the asymmetric segregation of proteins or mRNAs, when the two daughter cells differ in size or are endowed with different potentials to differentiate into a particular cell type (Horvitz and Herskowitz, Cell 68:237-255, 1992). Drosophila neuroblasts, the neural stem cells of the developing fly brain, are an ideal system to study ACD since this system encompasses all of these characteristics. Neuroblasts are intrinsically polarized cells, utilizing polarity cues to orient the mitotic spindle, segregate cell fate determinants asymmetrically, and regulate spindle geometry and physical asymmetry. The neuroblast system has contributed significantly to the elucidation of the basic molecular mechanisms underlying ACD. Recent findings also highlight its usefulness to study basic aspects of stem cell biology and tumor formation. In this review, we will focus on what has been learned about the basic mechanisms underlying ACD in fly neuroblasts.
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