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Coutinho-Budd J, Freeman MR, Ackerman S. Glial Regulation of Circuit Wiring, Firing, and Expiring in the Drosophila Central Nervous System. Cold Spring Harb Perspect Biol 2024; 16:a041347. [PMID: 38565270 PMCID: PMC11513168 DOI: 10.1101/cshperspect.a041347] [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] [Indexed: 04/04/2024]
Abstract
Molecular genetic approaches in small model organisms like Drosophila have helped to elucidate fundamental principles of neuronal cell biology. Much less is understood about glial cells, although interest in using invertebrate preparations to define their in vivo functions has increased significantly in recent years. This review focuses on our current understanding of the three major neuron-associated glial cell types found in the Drosophila central nervous system (CNS)-astrocytes, cortex glia, and ensheathing glia. Together, these cells act like mammalian astrocytes and microglia; they associate closely with neurons including surrounding neuronal cell bodies and proximal neurites, regulate synapses, and engulf neuronal debris. Exciting recent work has shown critical roles for these CNS glial cells in neural circuit formation, function, plasticity, and pathology. As we gain a more firm molecular and cellular understanding of how Drosophila CNS glial cells interact with neurons, it is clear that they share significant molecular and functional attributes with mammalian glia and will serve as an excellent platform for mechanistic studies of glial function.
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Affiliation(s)
- Jaeda Coutinho-Budd
- Department of Neuroscience, Center for Brain Immunology and Glia, University of Virginia, Charlottesville, Virginia 22903, USA
| | - Marc R Freeman
- Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - Sarah Ackerman
- Department of Pathology and Immunology, Brain Immunology and Glia Center, and Department of Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA
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2
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Purice MD, Lago-Baldaia I, Fernandes VM, Singhvi A. Molecular profiling of invertebrate glia. Glia 2024. [PMID: 39415317 DOI: 10.1002/glia.24623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 09/06/2024] [Accepted: 09/18/2024] [Indexed: 10/18/2024]
Abstract
Caenorhabditis elegans and Drosophila melanogaster are powerful experimental models for uncovering fundamental tenets of nervous system organization and function. Findings over the last two decades show that molecular and cellular features are broadly conserved between invertebrates and vertebrates, indicating that insights derived from invertebrate models can broadly inform our understanding of glial operating principles across diverse species. In recent years, these model systems have led to exciting discoveries in glial biology and mechanisms of glia-neuron interactions. Here, we summarize studies that have applied current state-of-the-art "-omics" techniques to C. elegans and D. melanogaster glia. Coupled with the remarkable acceleration in the pace of mechanistic studies of glia biology in recent years, these indicate that invertebrate glia also exhibit striking molecular complexity, specificity, and heterogeneity. We provide an overview of these studies and discuss their implications as well as emerging questions where C. elegans and D. melanogaster are well-poised to fill critical knowledge gaps in our understanding of glial biology.
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Affiliation(s)
- Maria D Purice
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, Washington, USA
- Department of Biological Structure, School of Medicine, University of Washington, Seattle, Washington, USA
| | - Inês Lago-Baldaia
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Vilaiwan M Fernandes
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, Washington, USA
- Department of Biological Structure, School of Medicine, University of Washington, Seattle, Washington, USA
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3
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Beachum AN, Salazar G, Nachbar A, Krause K, Klose H, Meyer K, Maserejian A, Ross G, Boyd H, Weigel T, Ambaye L, Miller H, Coutinho-Budd J. Glia multitask to compensate for neighboring glial cell dysfunction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.06.611719. [PMID: 39314422 PMCID: PMC11418964 DOI: 10.1101/2024.09.06.611719] [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: 09/25/2024]
Abstract
As glia mature, they undergo glial tiling to abut one another without invading each other's boundaries. Upon the loss of the secreted neurotrophin Spätzle3 (Spz3), Drosophila cortex glia transform morphologically and lose their intricate interactions with neurons and surrounding glial subtypes. Here, we reveal that all neighboring glial cell types (astrocytes, ensheathing glia, and subperineurial glia) react by extending processes into the previous cortex glial territory to compensate for lost cortex glial function and reduce the buildup of neuronal debris. However, the loss of Spz3 alone is not sufficient for glia to cross their natural borders, as blocking CNS growth via nutrient-restriction blocks the aberrant infiltration induced by the loss of Spz3. Surprisingly, even when these neighboring glia divert their cellular resources beyond their typical borders to take on new compensatory roles, they are able to multitask to continue to preserve their own normal functions to maintain CNS homeostasis.
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Affiliation(s)
- Allison N. Beachum
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
| | - Gabriela Salazar
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
| | - Amelia Nachbar
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
| | - Kevin Krause
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
| | - Hannah Klose
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
| | - Kate Meyer
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
| | | | - Grace Ross
- Department of Biology, University of Vermont, Burlington, VT 05405
| | - Hannah Boyd
- Department of Biology, University of Vermont, Burlington, VT 05405
| | - Thaddeus Weigel
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
| | - Lydia Ambaye
- Department of Biology, University of Vermont, Burlington, VT 05405
| | - Hayes Miller
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
| | - Jaeda Coutinho-Budd
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
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Stansak KL, Baum LD, Ghosh S, Thapa P, Vanga V, Walters BJ. PCP auto count: a novel Fiji/ImageJ plug-in for automated quantification of planar cell polarity and cell counting. Front Cell Dev Biol 2024; 12:1394031. [PMID: 38827526 PMCID: PMC11140036 DOI: 10.3389/fcell.2024.1394031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 04/19/2024] [Indexed: 06/04/2024] Open
Abstract
Introdution: During development, planes of cells give rise to complex tissues and organs. The proper functioning of these tissues is critically dependent on proper inter- and intra-cellular spatial orientation, a feature known as planar cell polarity (PCP). To study the genetic and environmental factors affecting planar cell polarity, investigators must often manually measure cell orientations, which is a time-consuming endeavor. To automate cell counting and planar cell polarity data collection we developed a Fiji/ImageJ plug-in called PCP Auto Count (PCPA). Methods: PCPA analyzes binary images and identifies "chunks" of white pixels that contain "caves" of infiltrated black pixels. For validation, inner ear sensory epithelia including cochleae and utricles from mice were immunostained for βII-spectrin and imaged with a confocal microscope. Images were preprocessed using existing Fiji functionality to enhance contrast, make binary, and reduce noise. An investigator rated PCPA cochlear hair cell angle measurements for accuracy using a one to five agreement scale. For utricle samples, PCPA derived measurements were directly compared against manually derived angle measurements and the concordance correlation coefficient (CCC) and Bland-Altman limits of agreement were calculated. PCPA was also tested against previously published images examining PCP in various tissues and across various species suggesting fairly broad utility. Results: PCPA was able to recognize and count 99.81% of cochlear hair cells, and was able to obtain ideally accurate planar cell polarity measurements for at least 96% of hair cells. When allowing for a <10° deviation from "perfect" measurements, PCPA's accuracy increased to 98%-100% for all users and across all samples. When PCPA's measurements were compared with manual angle measurements for E17.5 utricles there was negligible bias (<0.5°), and a CCC of 0.999. Qualitative examination of example images of Drosophila ommatidia, mouse ependymal cells, and mouse radial progenitors revealed a high level of accuracy for PCPA across a variety of stains, tissue types, and species. Discussion: Altogether, the data suggest that the PCPA plug-in suite is a robust and accurate tool for the automated collection of cell counts and PCP angle measurements.
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Affiliation(s)
| | | | | | | | | | - Bradley J. Walters
- University of Mississippi Medical Center, Department of Otolaryngology—Head and Neck Surgery, Jackson, MS, United States
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Stansak KL, Baum LD, Ghosh S, Thapa P, Vanga V, Walters BJ. PCP Auto Count: A Novel Fiji/ImageJ plug-in for automated quantification of planar cell polarity and cell counting. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.30.578047. [PMID: 38352473 PMCID: PMC10862842 DOI: 10.1101/2024.01.30.578047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Background During development, planes of cells give rise to complex tissues and organs. The proper functioning of these tissues is critically dependent on proper inter- and intra-cellular spatial orientation, a feature known as planar cell polarity (PCP). To study the genetic and environmental factors affecting planar cell polarity investigators must often manually measure cell orientations, which is a time-consuming endeavor. Methodology To automate cell counting and planar cell polarity data collection we developed a Fiji/ImageJ plug-in called PCP Auto Count (PCPA). PCPA analyzes binary images and identifies "chunks" of white pixels that contain "caves" of infiltrated black pixels. Inner ear sensory epithelia including cochleae (P4) and utricles (E17.5) from mice were immunostained for βII-spectrin and imaged on a confocal microscope. Images were preprocessed using existing Fiji functionality to enhance contrast, make binary, and reduce noise. An investigator rated PCPA cochlear angle measurements for accuracy using a 1-5 agreement scale. For utricle samples, we directly compared PCPA derived measurements against manually derived angle measurements using concordance correlation coefficients (CCC) and Bland-Altman limits of agreement. Finally, PCPA was tested against a variety of images copied from publications examining PCP in various tissues and across various species. Results PCPA was able to recognize and count 99.81% of cochlear hair cells (n = 1,1541 hair cells) in a sample set, and was able to obtain ideally accurate planar cell polarity measurements for over 96% of hair cells. When allowing for a <10° deviation from "perfect" measurements, PCPA's accuracy increased to >98%. When manual angle measurements for E17.5 utricles were compared, PCPA's measurements fell within -9 to +10 degrees of manually obtained mean angle measures with a CCC of 0.999. Qualitative examination of example images of Drosophila ommatidia, mouse ependymal cells, and mouse radial progenitors revealed a high level of accuracy for PCPA across a variety of stains, tissue types, and species. Altogether, the data suggest that the PCPA plug-in suite is a robust and accurate tool for the automated collection of cell counts and PCP angle measurements.
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Affiliation(s)
- Kendra L. Stansak
- Department of Otolaryngology - Head and Neck Surgery, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Luke D. Baum
- Department of Otolaryngology - Head and Neck Surgery, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Sumana Ghosh
- Department of Otolaryngology - Head and Neck Surgery, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Punam Thapa
- Department of Otolaryngology - Head and Neck Surgery, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Vineel Vanga
- Department of Otolaryngology - Head and Neck Surgery, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Bradley J. Walters
- Department of Otolaryngology - Head and Neck Surgery, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
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Yadav V, Mishra R, Das P, Arya R. Cut homeodomain transcription factor is a novel regulator of growth and morphogenesis of cortex glia niche around neural cells. Genetics 2024; 226:iyad173. [PMID: 37751321 PMCID: PMC11491519 DOI: 10.1093/genetics/iyad173] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 09/28/2023] Open
Abstract
Cortex glia in Drosophila central nervous system form a niche around neural cells for necessary signals to establish cross talk with their surroundings. These cells grow and expand their thin processes around neural cell bodies. Although essential for the development and function of the nervous system, how these cells make extensive and intricate connected networks remains largely unknown. In this study, we show that Cut, a homeodomain transcription factor, directly regulates the fate of the cortex glia, impacting neural stem cell (NSC) homeostasis. Focusing on the thoracic ventral nerve cord, we found that Cut is required for the normal growth and development of cortex glia and timely increase in DNA content through endocycle to later divide via acytokinetic mitosis. Knockdown of Cut in cortex glia significantly reduces the growth of cellular processes, the network around NSCs, and their progeny's cell bodies. Conversely, overexpression of Cut induces overall growth of the main processes at the expense of side ones. Whereas the Cut knockdown slows down the timely increase of DNA, the Cut overexpression results in a significant increase in nuclear size and volume and a 3-fold increase in DNA content of cortex glia. Further, we note that constitutively high Cut also interfered with nuclei separation during acytokinetic mitosis. Since the cortex glia form syncytial networks around neural cells, the finding identifies Cut as a novel regulator of glial growth and variant cell cycles to support a functional nervous system.
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Affiliation(s)
- Vaishali Yadav
- Cytogenetics Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Ramkrishna Mishra
- Cytogenetics Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Papri Das
- Cytogenetics Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Richa Arya
- Cytogenetics Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, India
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Corty MM, Coutinho-Budd J. Drosophila glia take shape to sculpt the nervous system. Curr Opin Neurobiol 2023; 79:102689. [PMID: 36822142 PMCID: PMC10023329 DOI: 10.1016/j.conb.2023.102689] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/19/2022] [Accepted: 01/10/2023] [Indexed: 02/23/2023]
Abstract
The importance of glial cells has become increasingly apparent over the past 20 years, yet compared to neurons we still know relatively little about these essential cells. Most critical glial cell functions are conserved in Drosophila glia, often using the same key molecular players as their vertebrate counterparts. The relative simplicity of the Drosophila nervous system, combined with a vast array of powerful genetic tools, allows us to further dissect the molecular composition and functional roles of glia in ways that would be much more cumbersome or not possible in higher vertebrate systems. Importantly, Drosophila genetics allow for in vivo manipulation, and their transparent body wall enables in vivo imaging of glia in intact animals throughout early development. Here we discuss recent advances in Drosophila glial development detailing how these cells take on their mature morphologies and interact with neurons to perform their important functional roles in the nervous system.
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Affiliation(s)
- Megan M Corty
- Vollum Institute, Oregon Health & Science University, Portland, OR, USA. https://twitter.com/@megancphd
| | - Jaeda Coutinho-Budd
- Department of Neuroscience, University of Virginia, Charlottesville, VA, USA.
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