1
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Shinoda N, Horikoshi M, Taira Y, Muramoto M, Hirayama S, Murata S, Miura M. Caspase cleaves Drosophila BubR1 to modulate spindle assembly checkpoint function and lifespan of the organism. FEBS J 2023; 290:4200-4223. [PMID: 37151120 DOI: 10.1111/febs.16811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 03/23/2023] [Accepted: 05/04/2023] [Indexed: 05/09/2023]
Abstract
Caspases cleave over 1500 substrates in the human proteome in both lethal and non-lethal scenarios. However, reports of the physiological consequences of substrate cleavage are limited. Additionally, the manner in which caspase cleaves only a subset of substrates in the non-lethal scenario remains to be elucidated. BubR1, a spindle assembly checkpoint component, is a caspase substrate in humans, the physiological function of which remains unclear. Here, we found that caspases, especially Drice, cleave Drosophila BubR1 between the N-terminal KEN box motif and C-terminal kinase domain. By using proximity labelling, we found that Drice, but not Dcp-1, is in proximity to BubR1, suggesting that protein proximity facilitates substrate preference. The cleaved fragments displayed altered subcellular localization and protein-protein interactions. Flies that harboured cleavage-resistant BubR1 showed longer duration of BubR1 localization to the kinetochore upon colchicine treatment. Furthermore, these flies showed extended lifespan. Thus, we propose that the caspase-mediated cleavage of BubR1 limits spindle assembly checkpoint and organismal lifespan. Our results highlight the importance of the individual analysis of substrates in vivo to determine the biological significance of caspase-dependent non-lethal cellular processes.
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Affiliation(s)
- Natsuki Shinoda
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Japan
| | - Misuzu Horikoshi
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Japan
| | - Yusuke Taira
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Japan
| | - Masaya Muramoto
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Japan
| | - Shoshiro Hirayama
- Laboratory of Protein Metabolism, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Japan
| | - Shigeo Murata
- Laboratory of Protein Metabolism, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Japan
| | - Masayuki Miura
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Japan
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2
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Chippalkatti R, Egger B, Suter B. Mms19 promotes spindle microtubule assembly in Drosophila neural stem cells. PLoS Genet 2020; 16:e1008913. [PMID: 33211700 PMCID: PMC7714366 DOI: 10.1371/journal.pgen.1008913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 12/03/2020] [Accepted: 10/13/2020] [Indexed: 01/27/2023] Open
Abstract
Mitotic divisions depend on the timely assembly and proper orientation of the mitotic spindle. Malfunctioning of these processes can considerably delay mitosis, thereby compromising tissue growth and homeostasis, and leading to chromosomal instability. Loss of functional Mms19 drastically affects the growth and development of mitotic tissues in Drosophila larvae and we now demonstrate that Mms19 is an important factor that promotes spindle and astral microtubule (MT) growth, and MT stability and bundling. Mms19 function is needed for the coordination of mitotic events and for the rapid progression through mitosis that is characteristic of neural stem cells. Surprisingly, Mms19 performs its mitotic activities through two different pathways. By stimulating the mitotic kinase cascade, it triggers the localization of the MT regulatory complex TACC/Msps (Transforming Acidic Coiled Coil/Minispindles, the homolog of human ch-TOG) to the centrosome. This activity of Mms19 can be rescued by stimulating the mitotic kinase cascade. However, other aspects of the Mms19 phenotypes cannot be rescued in this way, pointing to an additional mechanism of Mms19 action. We provide evidence that Mms19 binds directly to MTs and that this stimulates MT stability and bundling.
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Affiliation(s)
- Rohan Chippalkatti
- Cell Biology, University of Bern, Berne, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Berne, Switzerland
| | - Boris Egger
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Beat Suter
- Cell Biology, University of Bern, Berne, Switzerland
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3
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Bostock MP, Prasad AR, Chaouni R, Yuen AC, Sousa-Nunes R, Amoyel M, Fernandes VM. An Immobilization Technique for Long-Term Time-Lapse Imaging of Explanted Drosophila Tissues. Front Cell Dev Biol 2020; 8:590094. [PMID: 33117817 PMCID: PMC7576353 DOI: 10.3389/fcell.2020.590094] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/15/2020] [Indexed: 01/19/2023] Open
Abstract
Time-lapse imaging is an essential tool to study dynamic biological processes that cannot be discerned from fixed samples alone. However, imaging cell- and tissue-level processes in intact animals poses numerous challenges if the organism is opaque and/or motile. Explant cultures of intact tissues circumvent some of these challenges, but sample drift remains a considerable obstacle. We employed a simple yet effective technique to immobilize tissues in medium-bathed agarose. We applied this technique to study multiple Drosophila tissues from first-instar larvae to adult stages in various orientations and with no evidence of anisotropic pressure or stress damage. Using this method, we were able to image fine features for up to 18 h and make novel observations. Specifically, we report that fibers characteristic of quiescent neuroblasts are inherited by their basal daughters during reactivation; that the lamina in the developing visual system is assembled roughly 2-3 columns at a time; that lamina glia positions are dynamic during development; and that the nuclear envelopes of adult testis cyst stem cells do not break down completely during mitosis. In all, we demonstrate that our protocol is well-suited for tissue immobilization and long-term live imaging, enabling new insights into tissue and cell dynamics in Drosophila.
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Affiliation(s)
- Matthew P. Bostock
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Anadika R. Prasad
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Rita Chaouni
- Centre for Developmental Neurobiology, King’s College London, London, United Kingdom
| | - Alice C. Yuen
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Rita Sousa-Nunes
- Centre for Developmental Neurobiology, King’s College London, London, United Kingdom
| | - Marc Amoyel
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Vilaiwan M. Fernandes
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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4
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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: 0.3] [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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5
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Hailstone M, Waithe D, Samuels TJ, Yang L, Costello I, Arava Y, Robertson E, Parton RM, Davis I. CytoCensus, mapping cell identity and division in tissues and organs using machine learning. eLife 2020; 9:e51085. [PMID: 32423529 PMCID: PMC7237217 DOI: 10.7554/elife.51085] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 03/17/2020] [Indexed: 01/16/2023] Open
Abstract
A major challenge in cell and developmental biology is the automated identification and quantitation of cells in complex multilayered tissues. We developed CytoCensus: an easily deployed implementation of supervised machine learning that extends convenient 2D 'point-and-click' user training to 3D detection of cells in challenging datasets with ill-defined cell boundaries. In tests on such datasets, CytoCensus outperforms other freely available image analysis software in accuracy and speed of cell detection. We used CytoCensus to count stem cells and their progeny, and to quantify individual cell divisions from time-lapse movies of explanted Drosophila larval brains, comparing wild-type and mutant phenotypes. We further illustrate the general utility and future potential of CytoCensus by analysing the 3D organisation of multiple cell classes in Zebrafish retinal organoids and cell distributions in mouse embryos. CytoCensus opens the possibility of straightforward and robust automated analysis of developmental phenotypes in complex tissues.
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Affiliation(s)
- Martin Hailstone
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - Dominic Waithe
- Wolfson Imaging Center & MRC WIMM Centre for Computational Biology MRC Weather all Institute of Molecular Medicine University of OxfordOxfordUnited Kingdom
| | - Tamsin J Samuels
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - Lu Yang
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - Ita Costello
- The Dunn School of Pathology,University of OxfordOxfordUnited Kingdom
| | - Yoav Arava
- Department of Biology, Technion - Israel Institute of TechnologyHaifaIsrael
| | | | - Richard M Parton
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
- Micron Advanced Bioimaging Unit, Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - Ilan Davis
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
- Micron Advanced Bioimaging Unit, Department of Biochemistry, University of OxfordOxfordUnited Kingdom
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6
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Liu X, Shen J, Xie L, Wei Z, Wong C, Li Y, Zheng X, Li P, Song Y. Mitotic Implantation of the Transcription Factor Prospero via Phase Separation Drives Terminal Neuronal Differentiation. Dev Cell 2020; 52:277-293.e8. [DOI: 10.1016/j.devcel.2019.11.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 10/09/2019] [Accepted: 11/26/2019] [Indexed: 11/26/2022]
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7
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Miszczak K, Egger B. Live Cell Imaging of Neural Stem Cells in the Drosophila Larval Brain. Methods Mol Biol 2020; 2047:153-160. [PMID: 31552654 DOI: 10.1007/978-1-4939-9732-9_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Live cell imaging gives valuable insights into the dynamic biological processes within and between cells. An important aspect of live cell imaging is to keep the cells under best physiological condition and to prevent abnormal cellular behavior, which might be caused by phototoxicity during microscopy. In this chapter we describe a protocol to visualize division patterns of neural stem cells in live whole mount brains of Drosophila larvae. We also present a newly developed live cell chamber that allows us to control the environmental air during live cell imaging. The protocol can be adapted to look at a wide range of cellular and tissue behavior in the Drosophila model system.
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Affiliation(s)
- Karolina Miszczak
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Boris Egger
- Department of Biology, University of Fribourg, Fribourg, Switzerland.
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8
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Ji T, Zhang L, Deng M, Huang S, Wang Y, Pham TT, Smith AA, Sridhar V, Cabernard C, Wang J, Yan Y. Dynamic MAPK signaling activity underlies a transition from growth arrest to proliferation in Drosophila scribble mutant tumors. Dis Model Mech 2019; 12:dmm.040147. [PMID: 31371383 PMCID: PMC6737955 DOI: 10.1242/dmm.040147] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/24/2019] [Indexed: 12/11/2022] Open
Abstract
Human tumors exhibit plasticity and evolving capacity over time. It is difficult to study the mechanisms of how tumors change over time in human patients, in particular during the early stages when a few oncogenic cells are barely detectable. Here, we used a Drosophila tumor model caused by loss of scribble (scrib), a highly conserved apicobasal cell polarity gene, to investigate the spatial-temporal dynamics of early tumorigenesis events. The fly scrib mutant tumors have been successfully used to model many aspects of tumorigenesis processes. However, it is still unknown whether Drosophila scrib mutant tumors exhibit plasticity and evolvability along the temporal axis. We found that scrib mutant tumors displayed different growth rates and cell cycle profiles over time, indicative of a growth arrest-to-proliferation transition as the scrib mutant tumors progress. Longitudinal bulk and single-cell transcriptomic analysis of scrib mutant tumors revealed that the MAPK pathway, including JNK and ERK signaling activities, showed quantitative changes over time. We found that high JNK signaling activity caused G2/M cell cycle arrest in early scrib mutant tumors. In addition, JNK signaling activity displayed a radial polarity with the JNKhigh cells located at the periphery of scrib mutant tumors, providing an inherent mechanism that leads to an overall decrease in JNK signaling activity over time. We also found that ERK signaling activity, in contrast to JNK activity, increased over time and promoted growth in late-stage scrib mutant tumors. Furthermore, high JNK signaling activity repressed ERK signaling activity in early scrib mutant tumors. Together, these data demonstrate that dynamic MAPK signaling activity, fueled by intratumor heterogeneity derived from tissue topological differences, drives a growth arrest-to-proliferation transition in scrib mutant tumors. This article has an associated First Person interview with the joint first authors of the paper. Summary: The authors provide evidence to show that a well-established Drosophila tumor model, caused by loss of apicobasal cell polarity, harbors a surprising degree of plasticity and evolvability along the temporal axis.
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Affiliation(s)
- Tiantian Ji
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Lina Zhang
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingxi Deng
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Shengshuo Huang
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.,Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Ying Wang
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Tri Thanh Pham
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA
| | - Andrew Alan Smith
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA
| | - Varun Sridhar
- 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
| | - Jiguang Wang
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.,Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yan Yan
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China .,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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9
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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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10
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Jia M, Meng D, Chen M, Li T, Zhang YQ, Yao A. Drosophila homolog of the intellectual disability-related long-chain acyl-CoA synthetase 4 is required for neuroblast proliferation. J Genet Genomics 2019; 46:5-17. [DOI: 10.1016/j.jgg.2018.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 10/29/2018] [Indexed: 11/27/2022]
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11
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Sabado V, Nagoshi E. Single-cell Resolution Fluorescence Live Imaging of Drosophila Circadian Clocks in Larval Brain Culture. J Vis Exp 2018. [PMID: 29443100 DOI: 10.3791/57015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The circadian pacemaker circuit orchestrates rhythmic behavioral and physiological outputs coordinated with environmental cues, such as day/night cycles. The molecular clock within each pacemaker neuron generates circadian rhythms in gene expression, which underlie the rhythmic neuronal functions essential to the operation of the circuit. Investigation of the properties of the individual molecular oscillators in different subclasses of pacemaker neurons and their interaction with neuronal signaling yields a better understanding of the circadian pacemaker circuit. Here, we present a time-lapse fluorescent microscopy approach developed to monitor the molecular clockwork in clock neurons of cultured Drosophila larval brain. This method allows the multi-day recording of the rhythms of genetically encoded fluorescent circadian reporters at single-cell resolution. This setup can be combined with pharmacological manipulations to closely analyze real-time response of the molecular clock to various compounds. Beyond circadian rhythms, this multipurpose method in combination with powerful Drosophila genetic techniques offers the possibility to study diverse neuronal or molecular processes in live brain tissue.
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Affiliation(s)
| | - Emi Nagoshi
- Department of Genetics and Evolution, University of Geneva;
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12
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Roubinet C, Tsankova A, Pham TT, Monnard A, Caussinus E, Affolter M, Cabernard C. Spatio-temporally separated cortical flows and spindle geometry establish physical asymmetry in fly neural stem cells. Nat Commun 2017; 8:1383. [PMID: 29123099 PMCID: PMC5680339 DOI: 10.1038/s41467-017-01391-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/04/2017] [Indexed: 01/09/2023] Open
Abstract
Asymmetric cell division, creating sibling cells with distinct developmental potentials, can be manifested in sibling cell size asymmetry. This form of physical asymmetry occurs in several metazoan cells, but the underlying mechanisms and function are incompletely understood. Here we use Drosophila neural stem cells to elucidate the mechanisms involved in physical asymmetry establishment. We show that Myosin relocalizes to the cleavage furrow via two distinct cortical Myosin flows: at anaphase onset, a polarity induced, basally directed Myosin flow clears Myosin from the apical cortex. Subsequently, mitotic spindle cues establish a Myosin gradient at the lateral neuroblast cortex, necessary to trigger an apically directed flow, removing Actomyosin from the basal cortex. On the basis of the data presented here, we propose that spatiotemporally controlled Myosin flows in conjunction with spindle positioning and spindle asymmetry are key determinants for correct cleavage furrow placement and cortical expansion, thereby establishing physical asymmetry.
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Affiliation(s)
- Chantal Roubinet
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Anna Tsankova
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- Streuli Pharma AG, Bahnhofstrasse 7, CH-8730, Uznach, Switzerland
| | - Tri Thanh Pham
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- Department of Biology, University of Washington, 24 Kincaid Hall, Seattle, WA, 98195, USA
| | - Arnaud Monnard
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- Department of Biology, University of Washington, 24 Kincaid Hall, Seattle, WA, 98195, USA
| | - Emmanuel Caussinus
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Markus Affolter
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
| | - Clemens Cabernard
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland.
- Department of Biology, University of Washington, 24 Kincaid Hall, Seattle, WA, 98195, USA.
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13
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Feoktistov AI, Herman TG. Wallenda/DLK protein levels are temporally downregulated by Tramtrack69 to allow R7 growth cones to become stationary boutons. Development 2016; 143:2983-93. [PMID: 27402706 DOI: 10.1242/dev.134403] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 06/23/2016] [Indexed: 11/20/2022]
Abstract
Dual leucine zipper kinase (DLK) promotes growth cone motility and must be restrained to ensure normal development. PHR (Pam/Highwire/RPM-1) ubiquitin ligases therefore target DLK for degradation unless axon injury occurs. Overall DLK levels decrease during development, but how DLK levels are regulated within a developing growth cone has not been examined. We analyzed the expression of the fly DLK Wallenda (Wnd) in R7 photoreceptor growth cones as they halt at their targets and become presynaptic boutons. We found that Wnd protein levels are repressed by the PHR protein Highwire (Hiw) during R7 growth cone halting, as has been observed in other systems. However, as R7 growth cones become boutons, Wnd levels are further repressed by a temporally expressed transcription factor, Tramtrack69 (Ttk69). Previously unobserved negative feedback from JNK also contributes to Wnd repression at both time points. We conclude that neurons deploy additional mechanisms to downregulate DLK as they form stable, synaptic connections. We use live imaging to probe the effects of Wnd and Ttk69 on R7 bouton development and conclude that Ttk69 coordinates multiple regulators of this process.
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Affiliation(s)
- Alexander I Feoktistov
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, OR 97403, USA
| | - Tory G Herman
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, OR 97403, USA
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14
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Ramdas Nair A, Singh P, Salvador Garcia D, Rodriguez-Crespo D, Egger B, Cabernard C. The Microcephaly-Associated Protein Wdr62/CG7337 Is Required to Maintain Centrosome Asymmetry in Drosophila Neuroblasts. Cell Rep 2016; 14:1100-1113. [PMID: 26804909 DOI: 10.1016/j.celrep.2015.12.097] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/10/2015] [Accepted: 12/21/2015] [Indexed: 12/31/2022] Open
Abstract
Centrosome asymmetry has been implicated in stem cell fate maintenance in both flies and vertebrates, but the underlying molecular mechanisms are incompletely understood. Here, we report that loss of CG7337, the fly ortholog of WDR62, compromises interphase centrosome asymmetry in fly neural stem cells (neuroblasts). Wdr62 maintains an active interphase microtubule-organizing center (MTOC) by stabilizing microtubules (MTs), which are necessary for sustained recruitment of Polo/Plk1 to the pericentriolar matrix (PCM) and downregulation of Pericentrin-like protein (Plp). The loss of an active MTOC in wdr62 mutants compromises centrosome positioning, spindle orientation, and biased centrosome segregation. wdr62 mutant flies also have an ∼40% reduction in brain size as a result of cell-cycle delays. We propose that CG7337/Wdr62, a microtubule-associated protein, is required for the maintenance of interphase microtubules, thereby regulating centrosomal Polo and Plp levels. Independent of this function, Wdr62 is also required for the timely mitotic entry of neural stem cells.
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Affiliation(s)
- Anjana Ramdas Nair
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, 4056 Basel, Switzerland
| | - Priyanka Singh
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, 4056 Basel, Switzerland
| | | | - David Rodriguez-Crespo
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Boris Egger
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Clemens Cabernard
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, 4056 Basel, Switzerland.
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15
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Pampalona J, Januschke J, Sampaio P, Gonzalez C. Time-lapse recording of centrosomes and other organelles in Drosophila neuroblasts. Methods Cell Biol 2015; 129:301-315. [PMID: 26175445 DOI: 10.1016/bs.mcb.2015.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Drosophila larval neuroblasts (NBs) are an excellent model for asymmetric division and cell cycle studies in general. For decades, visualizing relevant structures like centrosomes, chromosomes, or the mitotic spindle relied exclusively on immunofluorescence on fix samples. More recently, improvements on sensitivity and acquisition speed of different confocal systems have made it possible to acquire time-resolved images of combined fluorescent reporters from single larval NBs. Here, we provide protocols to visualize centrosomes and other organelles from both primary cultures of isolated single NBs and ex vivo, whole-mounted larval brains.
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Affiliation(s)
- Judit Pampalona
- Institute for Research in Biomedicine (IRB-Barcelona), Barcelona, Spain
| | - Jens Januschke
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, UK
| | - Paula Sampaio
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal; IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
| | - Cayetano Gonzalez
- Institute for Research in Biomedicine (IRB-Barcelona), Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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16
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Roth M, Roubinet C, Iffländer N, Ferrand A, Cabernard C. Asymmetrically dividing Drosophila neuroblasts utilize two spatially and temporally independent cytokinesis pathways. Nat Commun 2015; 6:6551. [PMID: 25791062 PMCID: PMC4544045 DOI: 10.1038/ncomms7551] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 02/04/2015] [Indexed: 01/09/2023] Open
Abstract
Precise cleavage furrow positioning is required for faithful chromosome segregation and cell fate determinant distribution. In most metazoan cells, contractile ring placement is regulated by the mitotic spindle through the centralspindlin complex, and potentially also the chromosomal passenger complex (CPC). Drosophila neuroblasts, asymmetrically dividing neural stem cells, but also other cells utilize both spindle-dependent and spindle-independent cleavage furrow positioning pathways. However, the relative contribution of each pathway towards cytokinesis is currently unclear. Here we report that in Drosophila neuroblasts, the mitotic spindle, but not polarity cues, controls the localization of the CPC component Survivin. We also show that Survivin and the mitotic spindle are required to stabilize the position of the cleavage furrow in late anaphase and to complete furrow constriction. These results support the model that two spatially and temporally separate pathways control different key aspects during asymmetric cell division, ensuring correct cell fate determinant segregation and neuroblast self-renewal. In asymmetrically dividing cells, both spindle-dependent and spindle-independent cleavage furrow positioning pathways are involved in cytokinesis. Here the authors find that Survivin and the mitotic spindle are required to stabilize the position of the cleavage furrow and to complete cytokinesis in Drosophila neuroblasts.
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Affiliation(s)
- Michaela Roth
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland
| | - Chantal Roubinet
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland
| | - Niklas Iffländer
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland
| | - Alexia Ferrand
- 1] Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland [2] Imaging Core Facility (IMCF), Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland
| | - Clemens Cabernard
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland
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17
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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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18
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Abstract
Stem cells divide asymmetrically to generate two progeny cells with unequal fate potential: a self-renewing stem cell and a differentiating cell. Given their relevance to development and disease, understanding the mechanisms that govern asymmetric stem cell division has been a robust area of study. Because they are genetically tractable and undergo successive rounds of cell division about once every hour, the stem cells of the Drosophila central nervous system, or neuroblasts, are indispensable models for the study of stem cell division. About 100 neural stem cells are located near the surface of each of the two larval brain lobes, making this model system particularly useful for live imaging microscopy studies. In this work, we review several approaches widely used to visualize stem cell divisions, and we address the relative advantages and disadvantages of those techniques that employ dissociated versus intact brain tissues. We also detail our simplified protocol used to explant whole brains from third instar larvae for live cell imaging and fixed analysis applications.
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Affiliation(s)
- Dorothy A Lerit
- National Heart, Lung, and Blood Institute, National Institutes of Health
| | - Karen M Plevock
- National Heart, Lung, and Blood Institute, National Institutes of Health
| | - Nasser M Rusan
- National Heart, Lung, and Blood Institute, National Institutes of Health;
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19
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The centriolar protein Bld10/Cep135 is required to establish centrosome asymmetry in Drosophila neuroblasts. Curr Biol 2014; 24:1548-55. [PMID: 24954048 DOI: 10.1016/j.cub.2014.05.050] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/06/2014] [Accepted: 05/21/2014] [Indexed: 01/12/2023]
Abstract
Centrosome asymmetry has been implicated in stem cell fate maintenance in both flies and vertebrates [1, 2]. Drosophila neuroblasts, the neural precursors of the fly's central nervous system [3], contain molecularly and physically asymmetric centrosomes, established through differences in pericentriolar matrix (PCM) retention [4-7]. For instance, the daughter centriole maintains PCM and thus microtubule-organizing center (MTOC) activity through Polo-mediated phosphorylation of Centrobin (Cnb) [7, 8]. The mother centriole, however, quickly downregulates PCM and moves away from the apical cortex, randomly migrating through the cytoplasm until maturation sets in at prophase [4-6, 8]. How PCM downregulation is molecularly controlled is currently unknown, but it involves Pericentrin (PCNT)-like protein (PLP) to prevent premature Polo localization and thus MTOC activity [9]. Here, we report that the centriolar protein Bld10, the fly ortholog of Cep135, is required to establish centrosome asymmetry in Drosophila neuroblasts through shedding of Polo from the mother centrosome. bld10 mutants fail to downregulate Polo and PCM, generating two active, improperly positioned MTOCs. Failure to shed Polo and PCM causes spindle alignment and centrosome segregation defects, resulting in neuroblasts incorrectly retaining the older mother centrosome. Since Cep135 is implicated in primary microcephaly, we speculate that perturbed centrosome asymmetry could contribute to this rare neurodevelopmental disease.
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