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Wu X, Cai Q, Feng Z, Zhang M. Liquid-Liquid Phase Separation in Neuronal Development and Synaptic Signaling. Dev Cell 2020; 55:18-29. [PMID: 32726576 DOI: 10.1016/j.devcel.2020.06.012] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/27/2020] [Accepted: 06/09/2020] [Indexed: 01/09/2023]
Abstract
Formation of biomolecular condensates that are not enclosed by membranes via liquid-liquid phase separation (LLPS) is a general strategy that cells adopt to organize membraneless subcellular compartments for diverse functions. Neurons are highly polarized with elaborate branching and functional compartmentalization of their neurites, thus, raising additional demand for the proper subcellular localization of both membraneless and membrane-based organelles. Recent studies have provided evidence that several protein assemblies involved in the establishment of neuronal stem cell (NSC) polarity and in the asymmetric division of NSCs form distinct molecular condensates via LLPS. In synapses of adult neurons, molecular apparatuses controlling presynaptic neurotransmitter release and postsynaptic signaling transmission are also likely formed via LLPS. These molecular condensates, though not enclosed by lipid bilayers, directly associate with plasma membranes or membrane-based organelles, indicating that direct communication between membraneless and membrane-based organelles is a common theme in neurons and other types of cells.
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Affiliation(s)
- Xiandeng Wu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Qixu Cai
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Zhe Feng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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2
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Liquid-liquid phase separation in biology: mechanisms, physiological functions and human diseases. SCIENCE CHINA. LIFE SCIENCES 2020; 63:953-985. [PMID: 32548680 DOI: 10.1007/s11427-020-1702-x] [Citation(s) in RCA: 151] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/20/2020] [Indexed: 02/06/2023]
Abstract
Cells are compartmentalized by numerous membrane-enclosed organelles and membraneless compartments to ensure that a wide variety of cellular activities occur in a spatially and temporally controlled manner. The molecular mechanisms underlying the dynamics of membrane-bound organelles, such as their fusion and fission, vesicle-mediated trafficking and membrane contactmediated inter-organelle interactions, have been extensively characterized. However, the molecular details of the assembly and functions of membraneless compartments remain elusive. Mounting evidence has emerged recently that a large number of membraneless compartments, collectively called biomacromolecular condensates, are assembled via liquid-liquid phase separation (LLPS). Phase-separated condensates participate in various biological activities, including higher-order chromatin organization, gene expression, triage of misfolded or unwanted proteins for autophagic degradation, assembly of signaling clusters and actin- and microtubule-based cytoskeletal networks, asymmetric segregations of cell fate determinants and formation of pre- and post-synaptic density signaling assemblies. Biomacromolecular condensates can transition into different material states such as gel-like structures and solid aggregates. The material properties of condensates are crucial for fulfilment of their distinct functions, such as biochemical reaction centers, signaling hubs and supporting architectures. Cells have evolved multiple mechanisms to ensure that biomacromolecular condensates are assembled and disassembled in a tightly controlled manner. Aberrant phase separation and transition are causatively associated with a variety of human diseases such as neurodegenerative diseases and cancers. This review summarizes recent major progress in elucidating the roles of LLPS in various biological pathways and diseases.
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3
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Carmena A. The Case of the Scribble Polarity Module in Asymmetric Neuroblast Division in Development and Tumorigenesis. Int J Mol Sci 2020; 21:ijms21082865. [PMID: 32325951 PMCID: PMC7215838 DOI: 10.3390/ijms21082865] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 12/29/2022] Open
Abstract
The Scribble polarity module is composed by Scribble (Scrib), Discs large 1 (Dlg1) and Lethal (2) giant larvae (L(2)gl), a group of highly conserved neoplastic tumor suppressor genes (TSGs) from flies to humans. Even though the Scribble module has been profusely studied in epithelial cell polarity, the number of tissues and processes in which it is involved is increasingly growing. Here we discuss the role of the Scribble module in the asymmetric division of Drosophila neuroblasts (NBs), as well as the underlying mechanisms by which those TSGs act in this process. Finally, we also describe what we know about the consequences of mutating these genes in impairing the process of asymmetric NB division and promoting tumor-like overgrowth.
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Affiliation(s)
- Ana Carmena
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas/Universidad Miguel Hernández, 03550 Sant Joan d'Alacant, Alicante, Spain
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4
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Abstract
Asymmetric cell division (ACD) is a conserved strategy for achieving cell diversity. A cell can undergo an intrinsic ACD through asymmetric segregation of cell fate determinants or cellular organelles. Recently, a new biophysical concept known as biomolecular phase separation, through which proteins and/or RNAs autonomously form a highly concentrated non-membrane-enclosed compartment via multivalent interactions, has provided new insights into the assembly and regulation of many membrane-less or membrane-attached organelles. Intriguingly, biomolecular phase separation is suggested to drive asymmetric condensation of cell fate determinants during ACD as well as organization of cellular organelles involved in ACD. In this Perspective, I first summarize recent findings on the molecular basis governing intrinsic ACD. Then I will discuss how ACD might be regulated by formation of dense molecular assemblies via phase separation.
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Affiliation(s)
- Wenyu Wen
- Department of Neurosurgery, Huashan Hospital, Institutes of Biomedical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai 200032 , China
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5
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Hu J, Cheng S, Wang H, Li X, Liu S, Wu M, Liu Y, Wang X. Distinct roles of two myosins in C. elegans spermatid differentiation. PLoS Biol 2019; 17:e3000211. [PMID: 30990821 PMCID: PMC6485759 DOI: 10.1371/journal.pbio.3000211] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 04/26/2019] [Accepted: 03/20/2019] [Indexed: 12/24/2022] Open
Abstract
During spermatogenesis, interconnected haploid spermatids segregate undesired cellular contents into residual bodies (RBs) before detaching from RBs. It is unclear how this differentiation process is controlled to produce individual spermatids or motile spermatozoa. Here, we developed a live imaging system to visualize and investigate this process in C. elegans. We found that non-muscle myosin 2 (NMY-2)/myosin II drives incomplete cytokinesis to generate connected haploid spermatids, which are then polarized to segregate undesired cellular contents into RBs under the control of myosin II and myosin VI. NMY-2/myosin II extends from the pseudo-cleavage furrow formed between two haploid spermatids to the spermatid poles, thus promoting RB expansion. In the meantime, defective spermatogenesis 15 (SPE-15)/myosin VI migrates from spermatids towards the expanding RB to promote spermatid budding. Loss of myosin II or myosin VI causes distinct cytoplasm segregation defects, while loss of both myosins completely blocks RB formation. We found that the final separation of spermatids from RBs is achieved through myosin VI-mediated cytokinesis, while myosin II is dispensable at this step. SPE-15/myosin VI and F-actin form a detergent-resistant actomyosin VI ring that undergoes continuous contraction to promote membrane constriction between spermatid and RB. We further identified that RGS-GAIP-interacting protein C terminus (GIPC)-1 and GIPC-2 cooperate with myosin VI to regulate contractile ring formation and spermatid release. Our study reveals distinct roles of myosin II and myosin VI in spermatid differentiation and uncovers a novel myosin VI-mediated cytokinesis process that controls spermatid release.
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Affiliation(s)
- Junyan Hu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shiya Cheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Haibin Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xin Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Sun Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Mengmeng Wu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yubing Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xiaochen Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- * E-mail:
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6
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Abstract
Selective enrichment of the polyphosphoinositides (PPIn), such as PtdIns(4,5)P2 and PtdIns4P, helps to determine the identity of the plasma membrane (PM) and regulates many aspects of cell biology through a vast number of protein effectors. Polarity proteins had long been assumed to be non-PPIn-binding proteins that mainly associate with PM/cell cortex through their extensive protein-protein interaction network. However, recent studies began to reveal that several key polarity proteins electrostatically bind to PPIn through their positively charged protein domains or structures and such PPIn-binding property is essential for their direct and specific attachment to PM. Although the physical nature of the charge-based PPIn binding appears to be simple and nonspecific, it serves as an elegant mechanism that can be efficiently and specifically regulated for achieving polarized PM targeting of polarity proteins. As an unexpected consequence, subcellular localization of PPIn-binding polarity proteins are also subject to regulations by physiological conditions such as hypoxia and ischemia that acutely and reversibly depletes PPIn from PM.
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Affiliation(s)
- Gerald R Hammond
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania 15261
| | - Yang Hong
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania 15261
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Hannaford MR, Ramat A, Loyer N, Januschke J. aPKC-mediated displacement and actomyosin-mediated retention polarize Miranda in Drosophila neuroblasts. eLife 2018; 7:29939. [PMID: 29364113 PMCID: PMC5783611 DOI: 10.7554/elife.29939] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 01/14/2018] [Indexed: 02/07/2023] Open
Abstract
Cell fate assignment in the nervous system of vertebrates and invertebrates often hinges on the unequal distribution of molecules during progenitor cell division. We address asymmetric fate determinant localization in the developing Drosophila nervous system, specifically the control of the polarized distribution of the cell fate adapter protein Miranda. We reveal a step-wise polarization of Miranda in larval neuroblasts and find that Miranda’s dynamics and cortical association are differently regulated between interphase and mitosis. In interphase, Miranda binds to the plasma membrane. Then, before nuclear envelope breakdown, Miranda is phosphorylated by aPKC and displaced into the cytoplasm. This clearance is necessary for the subsequent establishment of asymmetric Miranda localization. After nuclear envelope breakdown, actomyosin activity is required to maintain Miranda asymmetry. Therefore, phosphorylation by aPKC and differential binding to the actomyosin network are required at distinct phases of the cell cycle to polarize fate determinant localization in neuroblasts.
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Affiliation(s)
- Matthew Robert Hannaford
- Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Anne Ramat
- Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Nicolas Loyer
- Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Jens Januschke
- Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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8
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Wen W, Zhang M. Protein Complex Assemblies in Epithelial Cell Polarity and Asymmetric Cell Division. J Mol Biol 2017; 430:3504-3520. [PMID: 28963071 DOI: 10.1016/j.jmb.2017.09.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/16/2017] [Accepted: 09/19/2017] [Indexed: 12/24/2022]
Abstract
Asymmetric local concentration of protein complexes on distinct membrane regions is a fundamental property in numerous biological processes and is a hallmark of cell polarity. Evolutionarily conserved core polarity proteins form specific and dynamic networks to regulate the establishment and maintenance of cell polarity, as well as distinct polarity-driven cellular events. This review focuses on the molecular and structural basis governing regulated formation of several sets of core cell polarity regulatory complexes, as well as their functions in epithelial cell polarization and asymmetric cell division.
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Affiliation(s)
- Wenyu Wen
- Department of Neurosurgery, Huashan Hospital, Institutes of Biomedical Sciences, Fudan University, Shanghai 200040, China; Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, PR China.
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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9
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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: 2.6] [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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10
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Regulation of Asymmetric Cell Division in Mammalian Neural Stem and Cancer Precursor Cells. Results Probl Cell Differ 2017; 61:375-399. [PMID: 28409314 DOI: 10.1007/978-3-319-53150-2_17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Stem and progenitor cells are characterized by their abilities to self-renew and produce differentiated progeny. The balance between self-renewal and differentiation is achieved through control of cell division mode, which can be either asymmetric or symmetric. Failure to properly control cell division mode may result in premature depletion of the stem/progenitor cell pool or abnormal growth and impaired differentiation. In many tissues, including the brain, stem cells and progenitor cells undergo asymmetric cell division through the establishment of cell polarity. Cell polarity proteins are therefore potentially critical regulators of asymmetric cell division. Decrease or loss of asymmetric cell division can be associated with reduced differentiation common during aging or impaired remyelination as seen in demyelinating diseases. Progenitor-like glioma precursor cells show decreased asymmetric cell division rates and increased symmetric divisions, which suggests that asymmetric cell division suppresses brain tumor formation. Cancer stem cells, on the other hand, still undergo low rates of asymmetric cell division, which may provide them with a survival advantage during therapy. These findings led to the hypotheses that asymmetric cell divisions are not always tumor suppressive but can also be utilized to maintain a cancer stem cell population. Proper control of cell division mode is therefore not only deemed necessary to generate cellular diversity during development and to maintain adult tissue homeostasis but may also prevent disease and determine disease progression. Since brain cancer is most common in the adult and aging population, we review here the current knowledge on molecular mechanisms that regulate asymmetric cell divisions in the neural and oligodendroglial lineage during development and in the adult brain.
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11
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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: 4.9] [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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12
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Wollscheid HP, Biancospino M, He F, Magistrati E, Molteni E, Lupia M, Soffientini P, Rottner K, Cavallaro U, Pozzoli U, Mapelli M, Walters KJ, Polo S. Diverse functions of myosin VI elucidated by an isoform-specific α-helix domain. Nat Struct Mol Biol 2016; 23:300-308. [PMID: 26950368 PMCID: PMC4964928 DOI: 10.1038/nsmb.3187] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 02/09/2016] [Indexed: 01/01/2023]
Abstract
Myosin VI functions in endocytosis and cell motility. Alternative splicing of myosin VI mRNA generates two distinct isoform types, myosin VIshort and myosin VIlong, which differ in the C-terminal region. Their physiological and pathological role remains unknown. Here we identified an isoform-specific regulatory helix, named α2-linker that defines specific conformations and hence determines the target selectivity of human myosin VI. The presence of the α2-linker structurally defines a novel clathrin-binding domain that is unique to myosin VIlong and masks the known RRL interaction motif. This finding is relevant to ovarian cancer, where alternative myosin VI splicing is aberrantly regulated, and exon skipping dictates cell addiction to myosin VIshort for tumor cell migration. The RRL interactor optineurin contributes to this process by selectively binding myosin VIshort. Thus the α2-linker acts like a molecular switch that assigns myosin VI to distinct endocytic (myosin VIlong) or migratory (myosin VIshort) functional roles.
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Affiliation(s)
| | - Matteo Biancospino
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan 20139, Italy
| | - Fahu He
- Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Elisa Magistrati
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan 20139, Italy
| | - Erika Molteni
- Computational Biology, Scientific Institute IRCCS E.MEDEA, Bosisio Parini 23842, Italy
| | - Michela Lupia
- Molecular Medicine Program, European Institute of Oncology, Milan 20141, Italy
| | - Paolo Soffientini
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan 20139, Italy
| | - Klemens Rottner
- Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany.,Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Ugo Cavallaro
- Molecular Medicine Program, European Institute of Oncology, Milan 20141, Italy
| | - Uberto Pozzoli
- Computational Biology, Scientific Institute IRCCS E.MEDEA, Bosisio Parini 23842, Italy
| | - Marina Mapelli
- Department of Experimental Oncology, European Institute of Oncology, Milan 20139, Italy
| | - Kylie J Walters
- Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Simona Polo
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan 20139, Italy.,Dipartimento di oncologia ed emato-oncologia (DIPO), Universita' degli Studi di Milano, Milan 20122, Italy
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13
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Zhang F, Huang ZX, Bao H, Cong F, Wang H, Chai PC, Xi Y, Ge W, Somers WG, Yang Y, Cai Y, Yang X. Phosphotyrosyl phosphatase activator facilitates Miranda localization through dephosphorylation in dividing neuroblasts. Development 2015. [DOI: 10.1242/dev.127233] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
The mechanism for the basal targeting of the Miranda (Mira) complex during the asymmetric division of Drosophila neuroblasts (NBs) is yet to be fully understood. We have identified conserved Phosphotyrosyl Phosphatase Activator (PTPA) as a novel mediator for the basal localization of the Mira complex in larval brain NBs. In ptpa NBs, Mira remains cytoplasmic during early mitosis where its basal localization is delayed until anaphase. Detailed analyses indicate that PTPA acts independently of, and prior to, aPKC activity to localize Mira. Mechanistically, our data show that the phosphorylation status of the Thr591 (T591) residue determines the subcellular localization of Mira and that PTPA facilitates the dephosphorylation of T591. Furthermore, PTPA associates with the Protein Phosphatase 4 complex to mediate Mira localization. Based on these results, a two-step process for Mira basal localization during NB division is revealed where PTPA/PP4-mediated cortical association followed by apical aPKC-mediated basal restriction.
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Affiliation(s)
- Fan Zhang
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Zhen-Xing Huang
- Institute of Molecular and Cell Biology, ASTAR, Singapore
- Temasek Life Sciences Laboratory, Singapore
| | - Hongcun Bao
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Fei Cong
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | | | | | - Yongmei Xi
- Institute of Genetics, School of Medicine, Zhejiang University, Zhejiang, China
| | - Wanzhong Ge
- Institute of Genetics, School of Medicine, Zhejiang University, Zhejiang, China
| | - W. Gregory Somers
- Department of Genetics, La Trobe Institute for Molecular Science (LIMS), La Trobe University, Melbourne, Australia
| | - Ying Yang
- Temasek Life Sciences Laboratory, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Yu Cai
- Temasek Life Sciences Laboratory, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Xiaohang Yang
- College of Life Sciences, Zhejiang University, Hangzhou, China
- Institute of Genetics, School of Medicine, Zhejiang University, Zhejiang, China
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14
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Keder A, Carmena A. Cytoplasmic protein motility and polarized sorting during asymmetric cell division. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2013; 2:797-808. [DOI: 10.1002/wdev.116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Sousa-Nunes R, Somers WG. Mechanisms of asymmetric progenitor divisions in the Drosophila central nervous system. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 786:79-102. [PMID: 23696353 DOI: 10.1007/978-94-007-6621-1_6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The Drosophila central nervous system develops from polarised asymmetric divisions of precursor cells, called neuroblasts. Decades of research on neuroblasts have resulted in a substantial understanding of the factors and molecular events responsible for fate decisions of neuroblasts and their progeny. Furthermore, the cell-cycle dependent mechanisms responsible for asymmetric cortical protein localisation, resulting in the unequal partitioning between daughters, are beginning to be exposed. Disruption to the appropriate partitioning of proteins between neuroblasts and differentiation-committed daughters can lead to supernumerary neuroblast-like cells and the formation of tumours. Many of the factors responsible for regulating asymmetric division of Drosophila neuroblasts are evolutionarily conserved and, in many cases, have been shown to play a functionally conserved role in mammalian neurogenesis. Recent genome-wide studies coupled with advancements in live-imaging technologies have opened further avenues of research into neuroblast biology. We review our current understanding of the molecular mechanisms regulating neuroblast divisions, a powerful system to model mammalian neurogenesis and tumourigenesis.
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Affiliation(s)
- Rita Sousa-Nunes
- MRC Centre for Developmental Neurobiology, King's College London, New Hunt's House, London, SE1 1UL, UK.
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16
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Hirth F. Stem Cells and Asymmetric Cell Division. Regen Med 2013. [DOI: 10.1007/978-94-007-5690-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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17
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Sugiarto S, Persson AI, Munoz EG, Waldhuber M, Lamagna C, Andor N, Hanecker P, Ayers-Ringler J, Phillips J, Siu J, Lim D, Vandenberg S, Stallcup W, Berger MS, Bergers G, Weiss WA, Petritsch C. Asymmetry-defective oligodendrocyte progenitors are glioma precursors. Cancer Cell 2011; 20:328-40. [PMID: 21907924 PMCID: PMC3297490 DOI: 10.1016/j.ccr.2011.08.011] [Citation(s) in RCA: 165] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 04/12/2011] [Accepted: 08/09/2011] [Indexed: 11/22/2022]
Abstract
Postnatal oligodendrocyte progenitor cells (OPC) self-renew, generate mature oligodendrocytes, and are a cellular origin of oligodendrogliomas. We show that the proteoglycan NG2 segregates asymmetrically during mitosis to generate OPC cells of distinct fate. NG2 is required for asymmetric segregation of EGFR to the NG2(+) progeny, which consequently activates EGFR and undergoes EGF-dependent proliferation and self-renewal. In contrast, the NG2(-) progeny differentiates. In a mouse model, decreased NG2 asymmetry coincides with premalignant, abnormal self-renewal rather than differentiation and with tumor-initiating potential. Asymmetric division of human NG2(+) cells is prevalent in non-neoplastic tissue but is decreased in oligodendrogliomas. Regulators of asymmetric cell division are misexpressed in low-grade oligodendrogliomas. Our results identify loss of asymmetric division associated with the neoplastic transformation of OPC.
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Affiliation(s)
- Sista Sugiarto
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
| | - Anders I. Persson
- Neurology and Pediatrics, University of California San Francisco, San Francisco, CA94143, USA
| | - Elena Gonzalez Munoz
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
| | - Markus Waldhuber
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
- MorphoSys AG, Munich, Germany
| | - Chrystelle Lamagna
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
- Laboratory Medicine, University of California San Francisco, San Francisco, CA94143, USA
| | - Noemi Andor
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
| | - Patrizia Hanecker
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
| | - Jennifer Ayers-Ringler
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
| | - Joanna Phillips
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
- Pathology, University of California San Francisco, San Francisco, CA94143, USA
| | - Jason Siu
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA94143, USA
| | - Daniel Lim
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA94143, USA
| | - Scott Vandenberg
- Department of Pathology, University of California San Diego, San Diego, CA92013, USA
| | - William Stallcup
- Burnham Institute for Medical Research, Cancer Research Center, La Jolla, CA92037, USA
| | - Mitchel S. Berger
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
- Helen Diller Family Comprehensive Cancer Center, San Francisco, CA94158
- Brain Tumor Research Center, University of California San Francisco, San Francisco, CA94143, USA
| | - Gabriele Bergers
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
- Anatomy, University of California San Francisco, San Francisco, CA94143, USA
- Helen Diller Family Comprehensive Cancer Center, San Francisco, CA94158
- Brain Tumor Research Center, University of California San Francisco, San Francisco, CA94143, USA
| | - William A. Weiss
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
- Neurology and Pediatrics, University of California San Francisco, San Francisco, CA94143, USA
- Helen Diller Family Comprehensive Cancer Center, San Francisco, CA94158
- Brain Tumor Research Center, University of California San Francisco, San Francisco, CA94143, USA
| | - Claudia Petritsch
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA94143, USA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA94143, USA
- Helen Diller Family Comprehensive Cancer Center, San Francisco, CA94158
- Brain Tumor Research Center, University of California San Francisco, San Francisco, CA94143, USA
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18
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Sousa-Nunes R, Somers WG. Phosphorylation and dephosphorylation events allow for rapid segregation of fate determinants during Drosophila neuroblast asymmetric divisions. Commun Integr Biol 2011; 3:46-9. [PMID: 20539782 DOI: 10.4161/cib.3.1.9635] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 07/24/2009] [Indexed: 01/29/2023] Open
Abstract
Drosophila neuroblasts display remarkable asymmetry throughout mitosis. The most prominent asymmetry is the size difference between daughter cells at cytokinesis. The larger cell retains stem cell identity, i.e., remains a neuroblast while the smaller cell, called a ganglion mother cell (GMC), will generate differentiated neural and glial progeny. Preceding this size difference, several protein complexes localize to opposite sides of the neuroblast cortex (apical and basal in the embryo and, by analogy, referred to as such in larval neuroblasts although their asymmetry no longer correlates with such axis). The plane of division is coordinated with this molecular asymmetry such that apical and basal complexes are unequally partitioned between the two daughter cells: apical complexes are inherited by the self-renewing neuroblast while basal complexes are inherited by the GMC. This unequal segregation has been extensively shown to be functionally significant. Apical complexes contain factors required for cellular selfrenewal and basal complexes contain factors required for the differentiation of the GMC progeny. Curiously, however, some "basal" neuroblast proteins such as the scaffold protein Miranda (Mira) and its associated fate determinant Prospero (Pros), are initially apically localized prior to translocating to the opposite side of the cell cortex by the onset of mitosis. This is because mira mRNA is apically enriched, where it remains throughout the cell cycle, suggesting that Mira protein is translated within the apical environment.1,2 The transition from apical to basal enrichment of Mira and Pros takes place within minutes.2 Here, we summarize the known phosphorylation events and roles during neuroblast asymmetric divisions, as well as very recent work, including our own, identifying the first protein phosphatases implicated in this process. We then discuss models previously proposed, as well as a new model, for apical-to-basal transition of the Mira complex in light of our new results.
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Kisiel M, Majumdar D, Campbell S, Stewart BA. Myosin VI contributes to synaptic transmission and development at the Drosophila neuromuscular junction. BMC Neurosci 2011; 12:65. [PMID: 21745401 PMCID: PMC3146895 DOI: 10.1186/1471-2202-12-65] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 07/11/2011] [Indexed: 12/15/2022] Open
Abstract
Background Myosin VI, encoded by jaguar (jar) in Drosophila melanogaster, is a unique member of the myosin superfamily of actin-based motor proteins. Myosin VI is the only myosin known to move towards the minus or pointed ends of actin filaments. Although Myosin VI has been implicated in numerous cellular processes as both an anchor and a transporter, little is known about the role of Myosin VI in the nervous system. We previously recovered jar in a screen for genes that modify neuromuscular junction (NMJ) development and here we report on the genetic analysis of Myosin VI in synaptic development and function using loss of function jar alleles. Results Our experiments on Drosophila third instar larvae revealed decreased locomotor activity, a decrease in NMJ length, a reduction in synaptic bouton number, and altered synaptic vesicle localization in jar mutants. Furthermore, our studies of synaptic transmission revealed alterations in both basal synaptic transmission and short-term plasticity at the jar mutant neuromuscular synapse. Conclusions Altogether these findings indicate that Myosin VI is important for proper synaptic function and morphology. Myosin VI may be functioning as an anchor to tether vesicles to the bouton periphery and, thereby, participating in the regulation of synaptic vesicle mobilization during synaptic transmission.
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Affiliation(s)
- Marta Kisiel
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd, Mississauga, ON L5L1C6, Canada
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20
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Anterior-posterior axis specification in Drosophila oocytes: identification of novel bicoid and oskar mRNA localization factors. Genetics 2011; 188:883-96. [PMID: 21625003 DOI: 10.1534/genetics.111.129312] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Drosophila melanogaster anterior-posterior axis is established during oogenesis by the localization of bicoid and oskar mRNAs to the anterior and posterior poles of the oocyte. Although genetic screens have identified some trans-acting factors required for the localization of these transcripts, other factors may have been missed because they also function at other stages of oogenesis. To circumvent this problem, we performed a screen for revertants and dominant suppressors of the bicaudal phenotype caused by expressing Miranda-GFP in the female germline. Miranda mislocalizes oskar mRNA/Staufen complexes to the oocyte anterior by coupling them to the bicoid localization pathway, resulting in the formation of an anterior abdomen in place of the head. In one class of revertants, Miranda still binds Staufen/oskar mRNA complexes, but does not localize to the anterior, identifying an anterior targeting domain at the N terminus of Miranda. This has an almost identical sequence to the N terminus of vertebrate RHAMM, which is also a large coiled-coil protein, suggesting that it may be a divergent Miranda ortholog. In addition, we recovered 30 dominant suppressors, including multiple alleles of the spectroplakin, short stop, a lethal complementation group that prevents oskar mRNA anchoring, and a female sterile complementation group that disrupts the anterior localization of bicoid mRNA in late oogenesis. One of the single allele suppressors proved to be a mutation in the actin nucleator, Cappuccino, revealing a previously unrecognized function of Cappuccino in pole plasm anchoring and the induction of actin filaments by Long Oskar protein.
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21
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Hirth F. Stem Cells and Asymmetric Cell Division. Regen Med 2011. [DOI: 10.1007/978-90-481-9075-1_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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22
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Neumüller RA, Knoblich JA. Dividing cellular asymmetry: asymmetric cell division and its implications for stem cells and cancer. Genes Dev 2009; 23:2675-99. [PMID: 19952104 DOI: 10.1101/gad.1850809] [Citation(s) in RCA: 297] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell division is commonly thought to involve the equal distribution of cellular components into the two daughter cells. During many cell divisions, however, proteins, membrane compartments, organelles, or even DNA are asymmetrically distributed between the two daughter cells. Here, we review the various types of asymmetries that have been described in yeast and in animal cells. Asymmetric segregation of protein determinants is particularly relevant for stem cell biology. We summarize the relevance of asymmetric cell divisions in various stem cell systems and discuss why defects in asymmetric cell division can lead to the formation of tumors.
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Affiliation(s)
- Ralph A Neumüller
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), 1030 Vienna, Austria
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23
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Kim DW, Hirth F. Genetic mechanisms regulating stem cell self-renewal and differentiation in the central nervous system of Drosophila. Cell Adh Migr 2009; 3:402-11. [PMID: 19421003 DOI: 10.4161/cam.3.4.8690] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Recent studies using the Drosophila central nervous system as a model have identified key molecules and mechanisms underlying stem cell self-renewal and differentiation. These studies suggest that proteins like Aurora-A, atypical protein kinase C, Prospero and Brain tumor act as key regulators in a tightly coordinated interplay between mitotic spindle orientation and asymmetric protein localization. These data also provide initial evidence that both processes are coupled to cell cycle progression and growth control, thereby regulating a binary switch between proliferative stem self-renewal and differentiative progenitor cell specification. Considering the evolutionary conservation of some of the mechanisms and molecules involved, these data provide a rationale and genetic model for understanding stem cell self-renewal and differentiation in general. The new data gained in Drosophila may therefore lead to conceptual advancements in understanding the aetiology and treatment of human neurological disorders such as brain tumor formation and neurodegenerative diseases.
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Affiliation(s)
- Dongwook W Kim
- MRC Centre for Neurodegeneration Research, Institute of Psychiatry, King's College London, London, UK
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24
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Atwood SX, Prehoda KE. aPKC phosphorylates Miranda to polarize fate determinants during neuroblast asymmetric cell division. Curr Biol 2009; 19:723-9. [PMID: 19375318 DOI: 10.1016/j.cub.2009.03.056] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 03/19/2009] [Accepted: 03/24/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND Asymmetric cell divisions generate daughter cells with distinct fates by polarizing fate determinants into separate cortical domains. Atypical protein kinase C (aPKC) is an evolutionarily conserved regulator of cell polarity. In Drosophila neuroblasts, apically restricted aPKC is required for segregation of neuronal differentiation factors such as Numb and Miranda to the basal cortical domain. Whereas Numb is polarized by direct aPKC phosphorylation, Miranda asymmetry is thought to occur via a complicated cascade of repressive interactions (aPKC -| Lgl -| myosin II -| Miranda). RESULTS Here we provide biochemical, cellular, and genetic data showing that aPKC directly phosphorylates Miranda to exclude it from the cortex and that Lgl antagonizes this activity. Miranda is phosphorylated by aPKC at several sites in its cortical localization domain and phosphorylation is necessary and sufficient for cortical displacement, suggesting that the repressive-cascade model is incorrect. In investigating key results that led to this model, we found that Y-27632, a Rho kinase inhibitor used to implicate myosin II, efficiently inhibits aPKC. Lgl3A, a nonphosphorylatable Lgl variant used to implicate Lgl in this process, inhibits the formation of apical aPKC crescents in neuroblasts. Furthermore, Lgl directly inhibits aPKC kinase activity. CONCLUSIONS Miranda polarization during neuroblast asymmetric cell division occurs by displacement from the apical cortex by direct aPKC phosphorylation. Rather than mediating Miranda cortical displacement, Lgl instead promotes aPKC asymmetry by regulating its activity. The role of myosin II in neuroblast polarization, if any, is unknown.
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Affiliation(s)
- Scott X Atwood
- Institute of Molecular Biology and Department of Chemistry, University of Oregon, Eugene, OR 97403, USA
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25
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Sousa-Nunes R, Chia W, Somers WG. Protein phosphatase 4 mediates localization of the Miranda complex during Drosophila neuroblast asymmetric divisions. Genes Dev 2009; 23:359-72. [PMID: 19204120 PMCID: PMC2648543 DOI: 10.1101/gad.1723609] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Asymmetric localization of cell fate determinants is a crucial step in neuroblast asymmetric divisions. Whereas several protein kinases have been shown to mediate this process, no protein phosphatase has so far been implicated. In a clonal screen of larval neuroblasts we identified the evolutionarily conserved Protein Phosphatase 4 (PP4) regulatory subunit PP4R3/Falafel (Flfl) as a key mediator specific for the localization of Miranda (Mira) and associated cell fate determinants during both interphase and mitosis. Flfl is predominantly nuclear during interphase/prophase and cytoplasmic after nuclear envelope breakdown. Analyses of nuclear excluded as well as membrane targeted versions of the protein suggest that the asymmetric cortical localization of Mira and its associated proteins during mitosis depends on cytoplasmic/membrane-associated Flfl, whereas nuclear Flfl is required to exclude the cell fate determinant Prospero (Pros), and consequently Mira, from the nucleus during interphase/prophase. Attenuating the function of either the catalytic subunit of PP4 (PP4C; Pp4-19C in Drosophila) or of another regulatory subunit, PP4R2 (PPP4R2r in Drosophila), leads to similar defects in the localization of Mira and associated proteins. Flfl is capable of directly interacting with Mira, and genetic analyses indicate that flfl acts in parallel to or downstream from the tumor suppressor lethal (2) giant larvae (lgl). Our findings suggest that Flfl may target PP4 to the MIra protein complex to facilitate dephosphorylation step(s) crucial for its cortical association/asymmetric localization.
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Affiliation(s)
- Rita Sousa-Nunes
- Department of Biological Sciences, Temasek Life Sciences Laboratory, National University of Singapore, Singapore
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