1
|
Adebambo TH, Flores MFM, Zhang SL, Lerit DA. Arsenic impairs Drosophila neural stem cell mitotic progression and sleep behavior in a tauopathy model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.05.606375. [PMID: 39149321 PMCID: PMC11326188 DOI: 10.1101/2024.08.05.606375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Despite established exposure limits, arsenic remains the most significant environmental risk factor detrimental to human health and is associated with carcinogenesis and neurotoxicity. Arsenic compromises neurodevelopment, and it is associated with peripheral neuropathy in adults. Exposure to heavy metals, such as arsenic, may also increase the risk of neurodegenerative disorders. Nevertheless, the molecular mechanisms underlying arsenic-induced neurotoxicity remain poorly understood. Elucidating how arsenic contributes to neurotoxicity may mitigate some of the risks associated with chronic sublethal exposure and inform future interventions. In this study, we examine the effects of arsenic exposure on Drosophila larval neurodevelopment and adult neurologic function. Consistent with prior work, we identify significant developmental delays and heightened mortality in response to arsenic. Within the developing larval brain, we identify a dose-dependent increase in brain volume. This aberrant brain growth is coupled with impaired mitotic progression of the neural stem cells (NSCs), progenitors of the neurons and glia of the central nervous system. Live imaging of cycling NSCs reveals significant delays in cell cycle progression upon arsenic treatment, leading to genomic instability. In adults, chronic arsenic exposure reduces neurologic function, such as locomotion. Finally, we show arsenic selectively impairs circadian rhythms in a humanized tauopathy model. These findings inform mechanisms of arsenic neurotoxicity and reveal sex-specific and genetic vulnerabilities to sublethal exposure.
Collapse
Affiliation(s)
- Temitope H. Adebambo
- Department of Cell Biology, Emory University School of Medicine, Atlanta GA 30322
| | | | - Shirley L. Zhang
- Department of Cell Biology, Emory University School of Medicine, Atlanta GA 30322
| | - Dorothy A. Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta GA 30322
- Winship Cancer Institute, Emory University, Atlanta GA 30322
| |
Collapse
|
2
|
Hailstock T, Terry D, Wardwell-Ozgo J, Robinson BV, Moberg KH, Lerit DA. Colorimetric Synchronization of Drosophila Larvae. Curr Protoc 2023; 3:e924. [PMID: 37861353 PMCID: PMC10608261 DOI: 10.1002/cpz1.924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
The rapid succession of events during development poses an inherent challenge to achieve precise synchronization required for rigorous, quantitative phenotypic and genotypic analyses in multicellular model organisms. Drosophila melanogaster is an indispensable model for studying the development and function of higher order organisms due to extensive genome homology, tractability, and its relatively short lifespan. Presently, nine Nobel prizes serve as a testament to the utility of this elegant model system. Ongoing advancements in genetic and molecular tools allow for the underlying mechanisms of human disease to be investigated in Drosophila. However, the absence of a method to precisely age-match tissues during larval development prevents further capitalization of this powerful model organism. Drosophila spends nearly half of its life cycle progressing through three morphologically distinct larval instar stages, during which the imaginal discs, precursors of mature adult external structures (e.g., eyes, legs, wings), grow and develop distinct cell fates. Other tissues, such as the central nervous system, undergo massive morphological changes during larval development. While these three larval stages and subsequent pupal stages have historically been identified based on the number of hours post egg-laying under standard laboratory conditions, a reproducible, efficient, and inexpensive method is required to accurately age-match larvae within the third instar. The third instar stage is of particular interest, as this developmental stage spans a 48-hr window during which larval tissues switch from proliferative to differentiation programs. Moreover, some genetic manipulations can lead to developmental delays, further compounding the need for precise age-matching between control and experimental samples. This article provides a protocol optimized for synchronous staging of Drosophila third instar larvae by colorimetric characterization and is useful for age-matching a variety of tissues for numerous downstream applications. We also provide a brief discussion of the technical challenges associated with successful application of this protocol. © 2023 Wiley Periodicals LLC. Basic Protocol: Synchronization of third instar Drosophila larvae.
Collapse
Affiliation(s)
- Taylor Hailstock
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
- equal contributors
| | - Douglas Terry
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
- equal contributors
| | - Joanna Wardwell-Ozgo
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
- equal contributors
- Kennesaw State University, College of Science and Maths, Department of Molecular and Cellular Biology, 370 Paulding Avenue Kennesaw, GA 30144
| | - Beverly V. Robinson
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
| | - Kenneth H. Moberg
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
| | - Dorothy A. Lerit
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
| |
Collapse
|
3
|
Fang HY, Forghani R, Clarke A, McQueen PG, Chandrasekaran A, O’Neill KM, Losert W, Papoian GA, Giniger E. Enabled primarily controls filopodial morphology, not actin organization, in the TSM1 growth cone in Drosophila. Mol Biol Cell 2023; 34:ar83. [PMID: 37223966 PMCID: PMC10398877 DOI: 10.1091/mbc.e23-01-0003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 05/25/2023] Open
Abstract
Ena/VASP proteins are processive actin polymerases that are required throughout animal phylogeny for many morphogenetic processes, including axon growth and guidance. Here we use in vivo live imaging of morphology and actin distribution to determine the role of Ena in promoting the growth of the TSM1 axon of the Drosophila wing. Altering Ena activity causes stalling and misrouting of TSM1. Our data show that Ena has a substantial impact on filopodial morphology in this growth cone but exerts only modest effects on actin distribution. This is in contrast to the main regulator of Ena, Abl tyrosine kinase, which was shown previously to have profound effects on actin and only mild effects on TSM1 growth cone morphology. We interpret these data as suggesting that the primary role of Ena in this axon may be to link actin to the morphogenetic processes of the plasma membrane, rather than to regulate actin organization itself. These data also suggest that a key role of Ena, acting downstream of Abl, may be to maintain consistent organization and reliable evolution of growth cone structure, even as Abl activity varies in response to guidance cues in the environment.
Collapse
Affiliation(s)
- Hsiao Yu Fang
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Rameen Forghani
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Akanni Clarke
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Philip G. McQueen
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Aravind Chandrasekaran
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20752
| | - Kate M. O’Neill
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
- Institute for Physical Sciences and Department of Physics, University of Maryland, College Park, MD 20752
| | - Wolfgang Losert
- Institute for Physical Sciences and Department of Physics, University of Maryland, College Park, MD 20752
| | - Garegin A. Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20752
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| |
Collapse
|
4
|
Warecki B, Bast I, Sullivan W. Visualizing the Dynamics of Cell Division by Live Imaging Drosophila Larval Brain Squashes. Methods Mol Biol 2022; 2415:37-46. [PMID: 34972944 DOI: 10.1007/978-1-0716-1904-9_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The dramatic changes of subcellular structures during mitosis are best visualized by live imaging. In general, live imaging requires the expression of proteins of interest fused to fluorophores and a model system amenable to live microscopy. Drosophila melanogaster is an attractive model in which to perform live imaging because of the numerous transgenic stocks bearing fluorescently tagged transgenes as well as the ability to precisely manipulate gene expression. Traditionally, the early Drosophila embryo has been used for live fluorescent analysis of mitotic events such as spindle formation and chromosome segregation. More recent studies demonstrate that the Drosophila third instar neuroblasts have a number of properties that make them well suited for live analysis: (1) neuroblasts are distinct cells surrounded by plasma membranes; (2) neuroblasts undergo a complete cell cycle, consisting of G1, S, G2, and M phases; and (3) neuroblasts gene expression is not influenced by maternal load, and so the genetics are therefore relatively more simple. Finally, the Drosophila neuroblast is arguably the best system for live imaging asymmetric stem cell divisions. Here, we detail a method for live imaging Drosophila larval neuroblasts.
Collapse
Affiliation(s)
- Brandt Warecki
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Ian Bast
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - William Sullivan
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, USA.
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Zhang S, Markey M, Pena CD, Venkatesh T, Vazquez M. A Micro-Optic Stalk (μOS) System to Model the Collective Migration of Retinal Neuroblasts. MICROMACHINES 2020; 11:mi11040363. [PMID: 32244321 PMCID: PMC7230939 DOI: 10.3390/mi11040363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/27/2020] [Accepted: 03/28/2020] [Indexed: 12/18/2022]
Abstract
Contemporary regenerative therapies have introduced stem-like cells to replace damaged neurons in the visual system by recapitulating critical processes of eye development. The collective migration of neural stem cells is fundamental to retinogenesis and has been exceptionally well-studied using the fruit fly model of Drosophila Melanogaster. However, the migratory behavior of its retinal neuroblasts (RNBs) has been surprisingly understudied, despite being critical to retinal development in this invertebrate model. The current project developed a new microfluidic system to examine the collective migration of RNBs extracted from the developing visual system of Drosophila as a model for the collective motile processes of replacement neural stem cells. The system scales with the microstructure of the Drosophila optic stalk, which is a pre-cursor to the optic nerve, to produce signaling fields spatially comparable to in vivo RNB stimuli. Experiments used the micro-optic stalk system, or μOS, to demonstrate the preferred sizing and directional migration of collective, motile RNB groups in response to changes in exogenous concentrations of fibroblast growth factor (FGF), which is a key factor in development. Our data highlight the importance of cell-to-cell contacts in enabling cell cohesion during collective RNB migration and point to the unexplored synergy of invertebrate cell study and microfluidic platforms to advance regenerative strategies.
Collapse
Affiliation(s)
- Stephanie Zhang
- Department of Biomedical Engineering, Binghamton University, 4400 Vestal Pkwy E, Binghamton, NY 13902, USA;
| | - Miles Markey
- Department of Biomedical Engineering, Rutgers University, 599 Taylor Rd, Piscataway, NJ 08854, USA;
| | - Caroline D. Pena
- Department of Biomedical Engineering, City College of New York, New York City, NY 10031, USA;
| | - Tadmiri Venkatesh
- Department of Biology, City College of New York, New York City, NY 10031, USA;
| | - Maribel Vazquez
- Department of Biomedical Engineering, Rutgers University, 599 Taylor Rd, Piscataway, NJ 08854, USA;
- Correspondence:
| |
Collapse
|
8
|
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]
|
9
|
Collective behaviors of Drosophila-derived retinal progenitors in controlled microenvironments. PLoS One 2019; 14:e0226250. [PMID: 31835272 PMCID: PMC6910854 DOI: 10.1371/journal.pone.0226250] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 11/24/2019] [Indexed: 12/29/2022] Open
Abstract
Collective behaviors of retinal progenitor cells (RPCs) are critical to the development of neural networks needed for vision. Signaling cues and pathways governing retinal cell fate, migration, and functional organization are remarkably conserved across species, and have been well-studied using Drosophila melanogaster. However, the collective migration of heterogeneous groups of RPCs in response to dynamic signaling fields of development remains incompletely understood. This is in large part because the genetic advances of seminal invertebrate models have been poorly complemented by in vitro cell study of its visual development. Tunable microfluidic assays able to replicate the miniature cellular microenvironments of the developing visual system provide newfound opportunities to probe and expand our knowledge of collective chemotactic responses essential to visual development. Our project used a controlled, microfluidic assay to produce dynamic signaling fields of Fibroblast Growth Factor (FGF) that stimulated the chemotactic migration of primary RPCs extracted from Drosophila. Results illustrated collective RPC chemotaxis dependent on average size of clustered cells, in contrast to the non-directional movement of individually-motile RPCs. Quantitative study of these diverse collective responses will advance our understanding of retina developmental processes, and aid study/treatment of inherited eye disease. Lastly, our unique coupling of defined invertebrate models with tunable microfluidic assays provides advantages for future quantitative and mechanistic study of varied RPC migratory responses.
Collapse
|
10
|
Pena CD, Zhang S, Majeska R, Venkatesh T, Vazquez M. Invertebrate Retinal Progenitors as Regenerative Models in a Microfluidic System. Cells 2019; 8:cells8101301. [PMID: 31652654 PMCID: PMC6829900 DOI: 10.3390/cells8101301] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/15/2019] [Accepted: 10/16/2019] [Indexed: 12/30/2022] Open
Abstract
Regenerative retinal therapies have introduced progenitor cells to replace dysfunctional or injured neurons and regain visual function. While contemporary cell replacement therapies have delivered retinal progenitor cells (RPCs) within customized biomaterials to promote viability and enable transplantation, outcomes have been severely limited by the misdirected and/or insufficient migration of transplanted cells. RPCs must achieve appropriate spatial and functional positioning in host retina, collectively, to restore vision, whereas movement of clustered cells differs substantially from the single cell migration studied in classical chemotaxis models. Defining how RPCs interact with each other, neighboring cell types and surrounding extracellular matrixes are critical to our understanding of retinogenesis and the development of effective, cell-based approaches to retinal replacement. The current article describes a new bio-engineering approach to investigate the migratory responses of innate collections of RPCs upon extracellular substrates by combining microfluidics with the well-established invertebrate model of Drosophila melanogaster. Experiments utilized microfluidics to investigate how the composition, size, and adhesion of RPC clusters on defined extracellular substrates affected migration to exogenous chemotactic signaling. Results demonstrated that retinal cluster size and composition influenced RPC clustering upon extracellular substrates of concanavalin (Con-A), Laminin (LM), and poly-L-lysine (PLL), and that RPC cluster size greatly altered collective migratory responses to signaling from Fibroblast Growth Factor (FGF), a primary chemotactic agent in Drosophila. These results highlight the significance of examining collective cell-biomaterial interactions on bio-substrates of emerging biomaterials to aid directional migration of transplanted cells. Our approach further introduces the benefits of pairing genetically controlled models with experimentally controlled microenvironments to advance cell replacement therapies.
Collapse
Affiliation(s)
- Caroline D Pena
- Department of Biomedical Engineering, City College of New York, New York, NY 10031, USA.
| | - Stephanie Zhang
- Department of Biomedical Engineering, The State University of New York at Binghamton, NY 13902, USA.
| | - Robert Majeska
- Department of Biomedical Engineering, City College of New York, New York, NY 10031, USA.
| | - Tadmiri Venkatesh
- Department of Biology, City College of New York, New York, NY 10031, USA.
| | - Maribel Vazquez
- Department of Biomedical Engineering, Rutgers University, The State University of New Jersey, New Brunswick, NJ 08854, USA.
| |
Collapse
|
11
|
Karabasheva D, Smyth JT. A novel, dynein-independent mechanism focuses the endoplasmic reticulum around spindle poles in dividing Drosophila spermatocytes. Sci Rep 2019; 9:12456. [PMID: 31462700 PMCID: PMC6713755 DOI: 10.1038/s41598-019-48860-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 08/14/2019] [Indexed: 01/04/2023] Open
Abstract
In dividing animal cells the endoplasmic reticulum (ER) concentrates around the poles of the spindle apparatus by associating with astral microtubules (MTs), and this association is essential for proper ER partitioning to progeny cells. The mechanisms that associate the ER with astral MTs are unknown. Because astral MT minus-ends are anchored by centrosomes at spindle poles, we hypothesized that the MT minus-end motor dynein mediates ER concentration around spindle poles. Live in vivo imaging of Drosophila spermatocytes revealed that dynein is required for ER concentration around centrosomes during late interphase. In marked contrast, however, dynein suppression had no effect on ER association with astral MTs and concentration around spindle poles in early M-phase. In fact, there was a sudden onset of ER association with astral MTs in dynein RNAi cells, revealing activation of an M-phase specific mechanism of ER-MT association. ER redistribution to spindle poles also did not require non-claret disjunctional (ncd), the other known Drosophila MT minus-end motor, nor Klp61F, a MT plus-end motor that generates spindle poleward forces. Collectively, our results suggest that a novel, M-phase specific mechanism of ER-MT association that is independent of MT minus-end motors is required for proper ER partitioning in dividing cells.
Collapse
Affiliation(s)
- Darya Karabasheva
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, F. Edward Hébert School of Medicine, Bethesda, MD, 20814, USA
| | - Jeremy T Smyth
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, F. Edward Hébert School of Medicine, Bethesda, MD, 20814, USA.
| |
Collapse
|
12
|
He L, Binari R, Huang J, Falo-Sanjuan J, Perrimon N. In vivo study of gene expression with an enhanced dual-color fluorescent transcriptional timer. eLife 2019; 8:46181. [PMID: 31140975 PMCID: PMC6660218 DOI: 10.7554/elife.46181] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/28/2019] [Indexed: 12/28/2022] Open
Abstract
Fluorescent transcriptional reporters are widely used as signaling reporters and biomarkers to monitor pathway activities and determine cell type identities. However, a large amount of dynamic information is lost due to the long half-life of the fluorescent proteins. To better detect dynamics, fluorescent transcriptional reporters can be destabilized to shorten their half-lives. However, applications of this approach in vivo are limited due to significant reduction of signal intensities. To overcome this limitation, we enhanced translation of a destabilized fluorescent protein and demonstrate the advantages of this approach by characterizing spatio-temporal changes of transcriptional activities in Drosophila. In addition, by combining a fast-folding destabilized fluorescent protein and a slow-folding long-lived fluorescent protein, we generated a dual-color transcriptional timer that provides spatio-temporal information about signaling pathway activities. Finally, we demonstrate the use of this transcriptional timer to identify new genes with dynamic expression patterns.
Collapse
Affiliation(s)
- Li He
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Richard Binari
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Boston, United States
| | - Jiuhong Huang
- International Academy of Targeted Therapeutics and Innovation, Chongqing University of Arts and Sciences, Chongqing, China
| | | | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Boston, United States
| |
Collapse
|
13
|
Janssen A, Colmenares SU, Lee T, Karpen GH. Timely double-strand break repair and pathway choice in pericentromeric heterochromatin depend on the histone demethylase dKDM4A. Genes Dev 2018; 33:103-115. [PMID: 30578303 PMCID: PMC6317320 DOI: 10.1101/gad.317537.118] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 10/29/2018] [Indexed: 12/22/2022]
Abstract
Repair of DNA double-strand breaks (DSBs) must be orchestrated properly within diverse chromatin domains in order to maintain genetic stability. Euchromatin and heterochromatin domains display major differences in histone modifications, biophysical properties, and spatiotemporal dynamics of DSB repair. However, it is unclear whether differential histone-modifying activities are required for DSB repair in these distinct domains. We showed previously that the Drosophila melanogaster KDM4A (dKDM4A) histone demethylase is required for heterochromatic DSB mobility. Here we used locus-specific DSB induction in Drosophila animal tissues and cultured cells to more deeply interrogate the impact of dKDM4A on chromatin changes, temporal progression, and pathway utilization during DSB repair. We found that dKDM4A promotes the demethylation of heterochromatin-associated histone marks at DSBs in heterochromatin but not euchromatin. Most importantly, we demonstrate that dKDM4A is required to complete DSB repair in a timely manner and regulate the relative utilization of homologous recombination (HR) and nonhomologous end-joining (NHEJ) repair pathways but exclusively for heterochromatic DSBs. We conclude that the temporal kinetics and pathway utilization during heterochromatic DSB repair depend on dKDM4A-dependent demethylation of heterochromatic histone marks. Thus, distinct pre-existing chromatin states require specialized epigenetic alterations to ensure proper DSB repair.
Collapse
Affiliation(s)
- Aniek Janssen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA.,Innovative Genomics Institute, Berkeley, California 94720, USA
| | - Serafin U Colmenares
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA.,Innovative Genomics Institute, Berkeley, California 94720, USA
| | - Timothy Lee
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Gary H Karpen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA.,Innovative Genomics Institute, Berkeley, California 94720, USA
| |
Collapse
|
14
|
Branco AT, Brito RM, Lemos B. Sex-specific adaptation and genomic responses to Y chromosome presence in female reproductive and neural tissues. Proc Biol Sci 2018; 284:rspb.2017.2062. [PMID: 29237855 DOI: 10.1098/rspb.2017.2062] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/06/2017] [Indexed: 12/21/2022] Open
Abstract
Y chromosomes typically harbour a small number of genes and an abundance of repetitive sequences. In Drosophila, the Y chromosome comprises multimegabase long segments of repetitive DNA and a handful of protein-coding genes. In mammals, the Y chromosome also harbours a disproportionally high abundance of repeats. Here, we built on a Drosophila melanogaster model in which the Y chromosome is decoupled from sexual determination. Genotypes were genetically identical for the autosomes, X chromosome, and mitochondria, but differ by the presence or dose of the Y chromosome. Addition of an extra Y chromosome had limited impact in males. However, the presence of a Y chromosome in females induced a disproportionate response in genes expressed in the ovaries as well as genes encoded by the mitochondrial genome. Furthermore, the data revealed significant consequences of Y chromosome presence in larvae neuronal tissue. This included the repression of genes implicated in reproductive behaviour, courtship, mating and synaptic function. Our findings exhibit the Y chromosome as a hotspot for sex-specific adaptation. They suggest roles for natural selection on Y-linked genetic elements exerting impact on sex-specific tissues as well as somatic tissues shared by males and females.
Collapse
Affiliation(s)
- Alan T Branco
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T. H. Chan School of Public Health, 665 Huntington Avenue, 02115, Boston, MA, USA
| | - Rute M Brito
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T. H. Chan School of Public Health, 665 Huntington Avenue, 02115, Boston, MA, USA
| | - Bernardo Lemos
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T. H. Chan School of Public Health, 665 Huntington Avenue, 02115, Boston, MA, USA
| |
Collapse
|
15
|
Abeysundara N, Simmonds AJ, Hughes SC. Moesin is involved in polarity maintenance and cortical remodeling during asymmetric cell division. Mol Biol Cell 2018; 29:419-434. [PMID: 29282284 PMCID: PMC6014166 DOI: 10.1091/mbc.e17-05-0294] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 12/08/2017] [Accepted: 12/13/2017] [Indexed: 01/17/2023] Open
Abstract
An intact actomyosin network is essential for anchoring polarity proteins to the cell cortex and maintaining cell size asymmetry during asymmetric cell division of Drosophila neuroblasts (NBs). However, the mechanisms that control changes in actomyosin dynamics during asymmetric cell division remain unclear. We find that the actin-binding protein, Moesin, is essential for NB proliferation and mitotic progression in the developing brain. During metaphase, phosphorylated Moesin (p-Moesin) is enriched at the apical cortex, and loss of Moesin leads to defects in apical polarity maintenance and cortical stability. This asymmetric distribution of p-Moesin is determined by components of the apical polarity complex and Slik kinase. During later stages of mitosis, p-Moesin localization shifts more basally, contributing to asymmetric cortical extension and myosin basal furrow positioning. Our findings reveal Moesin as a novel apical polarity protein that drives cortical remodeling of dividing NBs, which is essential for polarity maintenance and initial establishment of cell size asymmetry.
Collapse
Affiliation(s)
- Namal Abeysundara
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Andrew J Simmonds
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Sarah C Hughes
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| |
Collapse
|
16
|
Liu K, Shen D, Shen J, Gao SM, Li B, Wong C, Feng W, Song Y. The Super Elongation Complex Drives Neural Stem Cell Fate Commitment. Dev Cell 2017; 40:537-551.e6. [PMID: 28350987 DOI: 10.1016/j.devcel.2017.02.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 01/13/2017] [Accepted: 02/26/2017] [Indexed: 10/19/2022]
Abstract
Asymmetric stem cell division establishes an initial difference between a stem cell and its differentiating sibling, critical for maintaining homeostasis and preventing carcinogenesis. Yet the mechanisms that consolidate and lock in such initial fate bias remain obscure. Here, we use Drosophila neuroblasts to demonstrate that the super elongation complex (SEC) acts as an intrinsic amplifier to drive cell fate commitment. SEC is highly expressed in neuroblasts, where it promotes self-renewal by physically associating with Notch transcription activation complex and enhancing HES (hairy and E(spl)) transcription. HES in turn upregulates SEC activity, forming an unexpected self-reinforcing feedback loop with SEC. SEC inactivation leads to neuroblast loss, whereas its forced activation results in neural progenitor dedifferentiation and tumorigenesis. Our studies unveil an SEC-mediated intracellular amplifier mechanism in ensuring robustness and precision in stem cell fate commitment and provide mechanistic explanation for the highly frequent association of SEC overactivation with human cancers.
Collapse
Affiliation(s)
- Kun Liu
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Dan Shen
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Jingwen Shen
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Shihong M Gao
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Bo Li
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Chouin Wong
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Weidong Feng
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Yan Song
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
| |
Collapse
|
17
|
Janssen A, Breuer GA, Brinkman EK, van der Meulen AI, Borden SV, van Steensel B, Bindra RS, LaRocque JR, Karpen GH. A single double-strand break system reveals repair dynamics and mechanisms in heterochromatin and euchromatin. Genes Dev 2017; 30:1645-57. [PMID: 27474442 PMCID: PMC4973294 DOI: 10.1101/gad.283028.116] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 07/05/2016] [Indexed: 01/04/2023]
Abstract
Janssen et al. developed an in vivo single double-strand break (DSB) system for both heterochromatic and euchromatic loci in Drosophila melanogaster. Live imaging and sequence analysis of repair products reveal that DSBs in euchromatin and heterochromatin are repaired with similar kinetics, employ both NHEJ and HR, and can use homologous chromosomes as an HR template. Repair of DNA double-strand breaks (DSBs) must be properly orchestrated in diverse chromatin regions to maintain genome stability. The choice between two main DSB repair pathways, nonhomologous end-joining (NHEJ) and homologous recombination (HR), is regulated by the cell cycle as well as chromatin context. Pericentromeric heterochromatin forms a distinct nuclear domain that is enriched for repetitive DNA sequences that pose significant challenges for genome stability. Heterochromatic DSBs display specialized temporal and spatial dynamics that differ from euchromatic DSBs. Although HR is thought to be the main pathway used to repair heterochromatic DSBs, direct tests of this hypothesis are lacking. Here, we developed an in vivo single DSB system for both heterochromatic and euchromatic loci in Drosophila melanogaster. Live imaging of single DSBs in larval imaginal discs recapitulates the spatio–temporal dynamics observed for irradiation (IR)-induced breaks in cell culture. Importantly, live imaging and sequence analysis of repair products reveal that DSBs in euchromatin and heterochromatin are repaired with similar kinetics, employ both NHEJ and HR, and can use homologous chromosomes as an HR template. This direct analysis reveals important insights into heterochromatin DSB repair in animal tissues and provides a foundation for further explorations of repair mechanisms in different chromatin domains.
Collapse
Affiliation(s)
- Aniek Janssen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Gregory A Breuer
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut 06510, USA; Department of Experimental Pathology, Yale School of Medicine, New Haven, Connecticut 06510, USA
| | - Eva K Brinkman
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam 1066 CX, the Netherlands
| | - Annelot I van der Meulen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sean V Borden
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Bas van Steensel
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam 1066 CX, the Netherlands
| | - Ranjit S Bindra
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut 06510, USA; Department of Experimental Pathology, Yale School of Medicine, New Haven, Connecticut 06510, USA
| | - Jeannine R LaRocque
- Department of Human Science, School of Nursing and Health Studies, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Gary H Karpen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| |
Collapse
|
18
|
Smyth JT, Schoborg TA, Bergman ZJ, Riggs B, Rusan NM. Proper symmetric and asymmetric endoplasmic reticulum partitioning requires astral microtubules. Open Biol 2016; 5:rsob.150067. [PMID: 26289801 PMCID: PMC4554919 DOI: 10.1098/rsob.150067] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Mechanisms that regulate partitioning of the endoplasmic reticulum (ER) during cell division are largely unknown. Previous studies have mostly addressed ER partitioning in cultured cells, which may not recapitulate physiological processes that are critical in developing, intact tissues. We have addressed this by analysing ER partitioning in asymmetrically dividing stem cells, in which precise segregation of cellular components is essential for proper development and tissue architecture. We show that in Drosophila neural stem cells, called neuroblasts, the ER asymmetrically partitioned to centrosomes early in mitosis. This correlated closely with the asymmetric nucleation of astral microtubules (MTs) by centrosomes, suggesting that astral MT association may be required for ER partitioning by centrosomes. Consistent with this, the ER also associated with astral MTs in meiotic Drosophila spermatocytes and during syncytial embryonic divisions. Disruption of centrosomes in each of these cell types led to improper ER partitioning, demonstrating the critical role for centrosomes and associated astral MTs in this process. Importantly, we show that the ER also associated with astral MTs in cultured human cells, suggesting that this centrosome/astral MT-based partitioning mechanism is conserved across animal species.
Collapse
Affiliation(s)
- Jeremy T Smyth
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences-F. Edward Hébert School of Medicine, Bethesda, MD 20814, USA
| | - Todd A Schoborg
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Zane J Bergman
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Blake Riggs
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Nasser M Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| |
Collapse
|
19
|
Plevock KM, Galletta BJ, Slep KC, Rusan NM. Newly Characterized Region of CP190 Associates with Microtubules and Mediates Proper Spindle Morphology in Drosophila Stem Cells. PLoS One 2015; 10:e0144174. [PMID: 26649574 PMCID: PMC4674064 DOI: 10.1371/journal.pone.0144174] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 11/13/2015] [Indexed: 11/27/2022] Open
Abstract
CP190 is a large, multi-domain protein, first identified as a centrosome protein with oscillatory localization over the course of the cell cycle. During interphase it has a well-established role within the nucleus as a chromatin insulator. Upon nuclear envelope breakdown, there is a striking redistribution of CP190 to centrosomes and the mitotic spindle, in addition to the population at chromosomes. Here, we investigate CP190 in detail by performing domain analysis in cultured Drosophila S2 cells combined with protein structure determination by X-ray crystallography, in vitro biochemical characterization, and in vivo fixed and live imaging of cp190 mutant flies. Our analysis of CP190 identifies a novel N-terminal centrosome and microtubule (MT) targeting region, sufficient for spindle localization. This region consists of a highly conserved BTB domain and a linker region that serves as the MT binding domain. We present the 2.5 Å resolution structure of the CP190 N-terminal 126 amino acids, which adopts a canonical BTB domain fold and exists as a stable dimer in solution. The ability of the linker region to robustly localize to MTs requires BTB domain-mediated dimerization. Deletion of the linker region using CRISPR significantly alters spindle morphology and leads to DNA segregation errors in the developing Drosophila brain neuroblasts. Collectively, we highlight a multivalent MT-binding architecture in CP190, which confers distinct subcellular cytoskeletal localization and function during mitosis.
Collapse
Affiliation(s)
- Karen M. Plevock
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, United State of America
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina, 27599, United States of America
| | - Brian J. Galletta
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, United State of America
| | - Kevin C. Slep
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, 27599, United States of America
- * E-mail: (NMR); (KCS)
| | - Nasser M. Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, United State of America
- * E-mail: (NMR); (KCS)
| |
Collapse
|
20
|
Schoborg T, Zajac AL, Fagerstrom CJ, Guillen RX, Rusan NM. An Asp-CaM complex is required for centrosome-pole cohesion and centrosome inheritance in neural stem cells. J Cell Biol 2015; 211:987-98. [PMID: 26620907 PMCID: PMC4674283 DOI: 10.1083/jcb.201509054] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/27/2015] [Indexed: 01/29/2023] Open
Abstract
Calmodulin is required for abnormal spindle’s (Asp’s) ability to cross-link microtubules and ensure proper centrosome inheritance in neural stem cells, but it is dispensable for Asp’s role in brain size determination. The interaction between centrosomes and mitotic spindle poles is important for efficient spindle formation, orientation, and cell polarity. However, our understanding of the dynamics of this relationship and implications for tissue homeostasis remains poorly understood. Here we report that Drosophila melanogaster calmodulin (CaM) regulates the ability of the microcephaly-associated protein, abnormal spindle (Asp), to cross-link spindle microtubules. Both proteins colocalize on spindles and move toward spindle poles, suggesting that they form a complex. Our binding and structure–function analysis support this hypothesis. Disruption of the Asp–CaM interaction alone leads to unfocused spindle poles and centrosome detachment. This behavior leads to randomly inherited centrosomes after neuroblast division. We further show that spindle polarity is maintained in neuroblasts despite centrosome detachment, with the poles remaining stably associated with the cell cortex. Finally, we provide evidence that CaM is required for Asp’s spindle function; however, it is completely dispensable for Asp’s role in microcephaly suppression.
Collapse
Affiliation(s)
- Todd Schoborg
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Allison L Zajac
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Carey J Fagerstrom
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Rodrigo X Guillen
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Nasser M Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| |
Collapse
|
21
|
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.
Collapse
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
| |
Collapse
|