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Lin KY, Gujar MR, Lin J, Ding WY, Huang J, Gao Y, Tan YS, Teng X, Christine LSL, Kanchanawong P, Toyama Y, Wang H. Astrocytes control quiescent NSC reactivation via GPCR signaling-mediated F-actin remodeling. SCIENCE ADVANCES 2024; 10:eadl4694. [PMID: 39047090 DOI: 10.1126/sciadv.adl4694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Accepted: 06/18/2024] [Indexed: 07/27/2024]
Abstract
The transitioning of neural stem cells (NSCs) between quiescent and proliferative states is fundamental for brain development and homeostasis. Defects in NSC reactivation are associated with neurodevelopmental disorders. Drosophila quiescent NSCs extend an actin-rich primary protrusion toward the neuropil. However, the function of the actin cytoskeleton during NSC reactivation is unknown. Here, we reveal the fine filamentous actin (F-actin) structures in the protrusions of quiescent NSCs by expansion and super-resolution microscopy. We show that F-actin polymerization promotes the nuclear translocation of myocardin-related transcription factor, a microcephaly-associated transcription factor, for NSC reactivation and brain development. F-actin polymerization is regulated by a signaling cascade composed of G protein-coupled receptor Smog, G protein αq subunit, Rho1 guanosine triphosphatase, and Diaphanous (Dia)/Formin during NSC reactivation. Further, astrocytes secrete a Smog ligand folded gastrulation to regulate Gαq-Rho1-Dia-mediated NSC reactivation. Together, we establish that the Smog-Gαq-Rho1 signaling axis derived from astrocytes, an NSC niche, regulates Dia-mediated F-actin dynamics in NSC reactivation.
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Affiliation(s)
- Kun-Yang Lin
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Mahekta R Gujar
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Jiaen Lin
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Wei Yung Ding
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Jiawen Huang
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Yang Gao
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Ye Sing Tan
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Xiang Teng
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Low Siok Lan Christine
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Pakorn Kanchanawong
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Yusuke Toyama
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore, 117411, Singapore
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
| | - Hongyan Wang
- Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
- Integrative Sciences and Engineering Programme, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore
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2
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Nelson KA, Lenhart KF, Anllo L, DiNardo S. The Drosophila hematopoietic niche assembles through collective cell migration controlled by neighbor tissues and Slit-Robo signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.21.600069. [PMID: 38979182 PMCID: PMC11230208 DOI: 10.1101/2024.06.21.600069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Niches are often found in specific positions in tissues relative to the stem cells they support. Consistency of niche position suggests that placement is important for niche function. However, the complexity of most niches has precluded a thorough understanding of how their proper placement is established. To address this, we investigated the formation of a genetically tractable niche, the Drosophila Posterior Signaling Center (PSC), the assembly of which had not been previously explored. This niche controls hematopoietic progenitors of the lymph gland (LG). PSC cells were previously shown to be specified laterally in the embryo, but ultimately reside dorsally, at the LG posterior. Here, using live-imaging, we show that PSC cells migrate as a tight collective and associate with multiple tissues during their trajectory to the LG posterior. We find that Slit emanating from two extrinsic sources, visceral mesoderm and cardioblasts, is required for the PSC to remain a collective, and for its attachment to cardioblasts during migration. Without proper Slit-Robo signaling, PSC cells disperse, form aberrant contacts, and ultimately fail to reach their stereotypical position near progenitors. Our work characterizes a novel example of niche formation and identifies an extrinsic signaling relay that controls precise niche positioning.
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Affiliation(s)
- Kara A Nelson
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, 421 Curie Blvd. Philadelphia, PA 19104, United States
- Institute for Regenerative Medicine at the University of Pennsylvania, 3400 Civic Center Blvd. Philadelphia, PA 19104, United States
| | - Kari F Lenhart
- Department of Biology, Drexel University, 3245 Chestnut St. Philadelphia, PA 19104, United States
| | - Lauren Anllo
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, 421 Curie Blvd. Philadelphia, PA 19104, United States
- Institute for Regenerative Medicine at the University of Pennsylvania, 3400 Civic Center Blvd. Philadelphia, PA 19104, United States
| | - Stephen DiNardo
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, 421 Curie Blvd. Philadelphia, PA 19104, United States
- Institute for Regenerative Medicine at the University of Pennsylvania, 3400 Civic Center Blvd. Philadelphia, PA 19104, United States
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3
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Lin KY, Gujar MR, Lin J, Ding WY, Huang J, Gao Y, Tan YS, Teng X, Christine LSL, Kanchanawong P, Toyama Y, Wang H. Astrocytes control quiescent NSC reactivation via GPCR signaling-mediated F-actin remodeling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.11.584337. [PMID: 38903085 PMCID: PMC11188063 DOI: 10.1101/2024.03.11.584337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
The transitioning of neural stem cells (NSCs) between quiescent and proliferative states is fundamental for brain development and homeostasis. Defects in NSC reactivation are associated with neurodevelopmental disorders. Drosophila quiescent NSCs extend an actin-rich primary protrusion toward the neuropil. However, the function of the actin cytoskeleton during NSC reactivation is unknown. Here, we reveal the fine F-actin structures in the protrusions of quiescent NSCs by expansion and super-resolution microscopy. We show that F-actin polymerization promotes the nuclear translocation of Mrtf, a microcephaly-associated transcription factor, for NSC reactivation and brain development. F-actin polymerization is regulated by a signaling cascade composed of G-protein-coupled receptor (GPCR) Smog, G-protein αq subunit, Rho1 GTPase, and Diaphanous (Dia)/Formin during NSC reactivation. Further, astrocytes secrete a Smog ligand Fog to regulate Gαq-Rho1-Dia-mediated NSC reactivation. Together, we establish that the Smog-Gαq-Rho1 signaling axis derived from astrocytes, a NSC niche, regulates Dia-mediated F-actin dynamics in NSC reactivation.
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4
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Gujar MR, Gao Y, Teng X, Deng Q, Lin KY, Tan YS, Toyama Y, Wang H. Golgi-dependent reactivation and regeneration of Drosophila quiescent neural stem cells. Dev Cell 2023; 58:1933-1949.e5. [PMID: 37567172 DOI: 10.1016/j.devcel.2023.07.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 04/26/2023] [Accepted: 07/17/2023] [Indexed: 08/13/2023]
Abstract
The ability of stem cells to switch between quiescent and proliferative states is crucial for maintaining tissue homeostasis and regeneration. In Drosophila, quiescent neural stem cells (qNSCs) extend a primary protrusion, a hallmark of qNSCs. Here, we have found that qNSC protrusions can be regenerated upon injury. This regeneration process relies on the Golgi apparatus that acts as the major acentrosomal microtubule-organizing center in qNSCs. A Golgi-resident GTPase Arf1 and its guanine nucleotide exchange factor Sec71 promote NSC reactivation and regeneration via the regulation of microtubule growth. Arf1 physically associates with its new effector mini spindles (Msps)/XMAP215, a microtubule polymerase. Finally, Arf1 functions upstream of Msps to target the cell adhesion molecule E-cadherin to NSC-neuropil contact sites during NSC reactivation. Our findings have established Drosophila qNSCs as a regeneration model and identified Arf1/Sec71-Msps pathway in the regulation of microtubule growth and NSC reactivation.
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Affiliation(s)
- Mahekta R Gujar
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Yang Gao
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Xiang Teng
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore 117411, Singapore
| | - Qiannan Deng
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Kun-Yang Lin
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Ye Sing Tan
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Yusuke Toyama
- Mechanobiology Institute, Level 5, T-lab Building, 5A Engineering Drive 1, Singapore 117411, Singapore; Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Hongyan Wang
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Integrative Sciences and Engineering Programme, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore.
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5
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Gujar MR, Gao Y, Teng X, Ding WY, Lin J, Tan YS, Chew LY, Toyama Y, Wang H. Patronin/CAMSAP promotes reactivation and regeneration of Drosophila quiescent neural stem cells. EMBO Rep 2023; 24:e56624. [PMID: 37440685 PMCID: PMC10481672 DOI: 10.15252/embr.202256624] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 06/06/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023] Open
Abstract
The ability of stem cells to switch between quiescent and proliferative states is crucial for maintaining tissue homeostasis and regeneration. Drosophila quiescent neural stem cells (qNSCs) extend a primary protrusion that is enriched in acentrosomal microtubules and can be regenerated upon injury. Arf1 promotes microtubule growth, reactivation (exit from quiescence), and regeneration of qNSC protrusions upon injury. However, how Arf1 is regulated in qNSCs remains elusive. Here, we show that the microtubule minus-end binding protein Patronin/CAMSAP promotes acentrosomal microtubule growth and quiescent NSC reactivation. Patronin is important for the localization of Arf1 at Golgi and physically associates with Arf1, preferentially with its GDP-bound form. Patronin is also required for the regeneration of qNSC protrusion, likely via the regulation of microtubule growth. Finally, Patronin functions upstream of Arf1 and its effector Msps/XMAP215 to target the cell adhesion molecule E-cadherin to NSC-neuropil contact sites during NSC reactivation. Our findings reveal a novel link between Patronin/CAMSAP and Arf1 in the regulation of microtubule growth and NSC reactivation. A similar mechanism might apply to various microtubule-dependent systems in mammals.
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Affiliation(s)
- Mahekta R Gujar
- Neuroscience and Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
| | - Yang Gao
- Neuroscience and Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
| | - Xiang Teng
- Mechanobiology InstituteSingaporeSingapore
| | - Wei Yung Ding
- Neuroscience and Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
| | - Jiaen Lin
- Neuroscience and Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
| | - Ye Sing Tan
- Neuroscience and Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
| | - Liang Yuh Chew
- Neuroscience and Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
- Present address:
Temasek LifeSciences LaboratorySingaporeSingapore
| | - Yusuke Toyama
- Mechanobiology InstituteSingaporeSingapore
- Department of Biological SciencesNational University of SingaporeSingaporeSingapore
| | - Hongyan Wang
- Neuroscience and Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
- Department of Physiology, Yong Loo Lin School of MedicineNational University of SingaporeSingaporeSingapore
- Integrative Sciences and Engineering ProgrammeNational University of SingaporeSingaporeSingapore
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6
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Ferreira AAG, Desplan C. An Atlas of the Developing Drosophila Visual System Glia and Subcellular mRNA Localization of Transcripts in Single Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.06.552169. [PMID: 37609218 PMCID: PMC10441313 DOI: 10.1101/2023.08.06.552169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Glial cells are essential for proper nervous system development and function. To understand glial development and function, we comprehensively annotated glial cells in a single-cell mRNA-sequencing (scRNAseq) atlas of the developing Drosophila visual system. This allowed us to study their developmental trajectories, from larval to adult stages, and to understand how specific types of glia diversify during development. For example, neuropil glia that are initially transcriptionally similar in larvae, split into ensheathing and astrocyte-like glia during pupal stages. Other glial types, such as chiasm glia change gradually during development without splitting into two cell types. The analysis of scRNA-seq allowed us to discover that the transcriptome of glial cell bodies can be distinguished from that of their broken processes. The processes contain distinct enriched mRNAs that were validated in vivo. Therefore, we have identified most glial types in the developing optic lobe and devised a computational approach to identify mRNA species that are localized to cell bodies or cellular processes.
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Affiliation(s)
| | - Claude Desplan
- Department of Biology, New York University, New York, NY, USA
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7
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Segura RC, Cabernard C. Live-Cell Imaging of Drosophila melanogaster Third Instar Larval Brains. J Vis Exp 2023:10.3791/65538. [PMID: 37427933 PMCID: PMC10655794 DOI: 10.3791/65538] [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: 07/11/2023] Open
Abstract
Drosophila neural stem cells (neuroblasts, NBs hereafter) undergo asymmetric divisions, regenerating the self-renewing neuroblast, while also forming a differentiating ganglion mother cell (GMC), which will undergo one additional division to give rise to two neurons or glia. Studies in NBs have uncovered the molecular mechanisms underlying cell polarity, spindle orientation, neural stem cell self-renewal, and differentiation. These asymmetric cell divisions are readily observable via live-cell imaging, making larval NBs ideally suited for investigating the spatiotemporal dynamics of asymmetric cell division in living tissue. When properly dissected and imaged in nutrient-supplemented medium, NBs in explant brains robustly divide for 12-20 h. Previously described methods are technically difficult and may be challenging to those new to the field. Here, a protocol is described for the preparation, dissection, mounting, and imaging of live third-instar larval brain explants using fat body supplements. Potential problems are also discussed, and examples are provided for how this technique can be used.
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8
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Ion Channels in Gliomas-From Molecular Basis to Treatment. Int J Mol Sci 2023; 24:ijms24032530. [PMID: 36768856 PMCID: PMC9916861 DOI: 10.3390/ijms24032530] [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: 11/30/2022] [Revised: 01/11/2023] [Accepted: 01/17/2023] [Indexed: 01/31/2023] Open
Abstract
Ion channels provide the basis for the nervous system's intrinsic electrical activity. Neuronal excitability is a characteristic property of neurons and is critical for all functions of the nervous system. Glia cells fulfill essential supportive roles, but unlike neurons, they also retain the ability to divide. This can lead to uncontrolled growth and the formation of gliomas. Ion channels are involved in the unique biology of gliomas pertaining to peritumoral pathology and seizures, diffuse invasion, and treatment resistance. The emerging picture shows ion channels in the brain at the crossroads of neurophysiology and fundamental pathophysiological processes of specific cancer behaviors as reflected by uncontrolled proliferation, infiltration, resistance to apoptosis, metabolism, and angiogenesis. Ion channels are highly druggable, making them an enticing therapeutic target. Targeting ion channels in difficult-to-treat brain tumors such as gliomas requires an understanding of their extremely heterogenous tumor microenvironment and highly diverse molecular profiles, both representing major causes of recurrence and treatment resistance. In this review, we survey the current knowledge on ion channels with oncogenic behavior within the heterogeneous group of gliomas, review ion channel gene expression as genomic biomarkers for glioma prognosis and provide an update on therapeutic perspectives for repurposed and novel ion channel inhibitors and electrotherapy.
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9
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Greenspan LJ, Matunis EL. Live Imaging of the Drosophila Testis Stem Cell Niche. Methods Mol Biol 2023; 2677:113-125. [PMID: 37464238 DOI: 10.1007/978-1-0716-3259-8_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Live imaging of adult tissue stem cell niches provides key insights into the dynamic behavior of stem cells, their differentiating progeny, and their neighboring support cells, but few niches are amenable to this approach. Here, we discuss a technique for long-term live imaging of the Drosophila testis stem cell niche. Culturing whole testes ex vivo for up to 18 h allows for tracking of cell-type-specific behaviors under normal and various chemically or genetically modified conditions. Fixing and staining tissues after live imaging allows for the molecular confirmation of cell identity and behavior. By using live imaging in intact niches, we can better uncover the cellular and molecular mechanisms that regulate stem cell function in vivo.
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Affiliation(s)
- Leah J Greenspan
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Erika L Matunis
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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10
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Bostock MP, Prasad AR, Donoghue A, Fernandes VM. Photoreceptors generate neuronal diversity in their target field through a Hedgehog morphogen gradient in Drosophila. eLife 2022; 11:78093. [PMID: 36004721 PMCID: PMC9507128 DOI: 10.7554/elife.78093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 08/23/2022] [Indexed: 11/13/2022] Open
Abstract
Defining the origin of neuronal diversity is a major challenge in developmental neurobiology. The Drosophila visual system is an excellent paradigm to study how cellular diversity is generated. Photoreceptors from the eye disc grow their axons into the optic lobe and secrete Hedgehog (Hh) to induce the lamina, such that for every unit eye there is a corresponding lamina unit made up of post-mitotic precursors stacked into columns. Each differentiated column contains five lamina neuron types (L1-L5), making it the simplest neuropil in the optic lobe, yet how this diversity is generated was unknown. Here, we found that Hh pathway activity is graded along the distal-proximal axis of lamina columns and further determined that this gradient in pathway activity arises from a gradient of Hh ligand. We manipulated Hh pathway activity cell-autonomously in lamina precursors and non-cell autonomously by inactivating the Hh ligand, and by knocking it down in photoreceptors. These manipulations showed that different thresholds of activity specify unique cell identities, with more proximal cell types specified in response to progressively lower Hh levels. Thus, our data establish that Hh acts as a morphogen to pattern the lamina. Although, this is the first such report during Drosophila nervous system development, our work uncovers a remarkable similarity with the vertebrate neural tube, which is patterned by Sonic Hedgehog. Altogether, we show that differentiating neurons can regulate the neuronal diversity of their distant target fields through morphogen gradients.
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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
| | - Alicia Donoghue
- 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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11
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Yuen AC, Prasad AR, Fernandes VM, Amoyel M. A kinase translocation reporter reveals real-time dynamics of ERK activity in Drosophila. Biol Open 2022; 11:bio059364. [PMID: 35608229 PMCID: PMC9167624 DOI: 10.1242/bio.059364] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 04/28/2022] [Indexed: 12/12/2022] Open
Abstract
Extracellular signal-regulated kinase (ERK) lies downstream of a core signalling cascade that controls all aspects of development and adult homeostasis. Recent developments have led to new tools to image and manipulate the pathway. However, visualising ERK activity in vivo with high temporal resolution remains a challenge in Drosophila. We adapted a kinase translocation reporter (KTR) for use in Drosophila, which shuttles out of the nucleus when phosphorylated by ERK. We show that ERK-KTR faithfully reports endogenous ERK signalling activity in developing and adult tissues, and that it responds to genetic perturbations upstream of ERK. Using ERK-KTR in time-lapse imaging, we made two novel observations: firstly, sustained hyperactivation of ERK by expression of dominant-active epidermal growth factor receptor raised the overall level but did not alter the kinetics of ERK activity; secondly, the direction of migration of retinal basal glia correlated with their ERK activity levels, suggesting an explanation for the heterogeneity in ERK activity observed in fixed tissue. Our results show that KTR technology can be applied in Drosophila to monitor ERK activity in real-time and suggest that this modular tool can be further adapted to study other kinases. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
| | | | | | - Marc Amoyel
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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12
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Nguyen PK, Cheng LY. Non-autonomous regulation of neurogenesis by extrinsic cues: a Drosophila perspective. OXFORD OPEN NEUROSCIENCE 2022; 1:kvac004. [PMID: 38596708 PMCID: PMC10913833 DOI: 10.1093/oons/kvac004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/20/2022] [Accepted: 03/23/2022] [Indexed: 04/11/2024]
Abstract
The formation of a functional circuitry in the central nervous system (CNS) requires the correct number and subtypes of neural cells. In the developing brain, neural stem cells (NSCs) self-renew while giving rise to progenitors that in turn generate differentiated progeny. As such, the size and the diversity of cells that make up the functional CNS depend on the proliferative properties of NSCs. In the fruit fly Drosophila, where the process of neurogenesis has been extensively investigated, extrinsic factors such as the microenvironment of NSCs, nutrients, oxygen levels and systemic signals have been identified as regulators of NSC proliferation. Here, we review decades of work that explores how extrinsic signals non-autonomously regulate key NSC characteristics such as quiescence, proliferation and termination in the fly.
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Affiliation(s)
- Phuong-Khanh Nguyen
- Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- Department of Anatomy and Physiology, The University of Melbourne, Victoria 3010, Australia
| | - Louise Y Cheng
- Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Victoria 3010, Australia
- Department of Anatomy and Physiology, The University of Melbourne, Victoria 3010, Australia
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13
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Gujar MR, Wang H. A fly's eye view of quiescent neural stem cells. OXFORD OPEN NEUROSCIENCE 2022; 1:kvac001. [PMID: 38596705 PMCID: PMC10913722 DOI: 10.1093/oons/kvac001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 04/11/2024]
Abstract
The balance between proliferation and quiescence of stem cells is crucial in maintaining tissue homeostasis. Neural stem cells (NSCs) in the brain have the ability to be reactivated from a reversible quiescent state to generate new neurons. However, how NSCs transit between quiescence and reactivation remains largely elusive. Drosophila larval brain NSCs, also known as neuroblasts, have emerged as an excellent in vivo model to study molecular mechanisms underlying NSC quiescence and reactivation. Here, we discuss our current understanding of the molecular mechanisms underlying the reactivation of quiescent NSCs in Drosophila. We review the most recent advances on epigenetic regulations and microtubule cytoskeleton in Drosophila quiescent NSCs and their cross-talk with signaling pathways that are required in regulating NSC reactivation.
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Affiliation(s)
- Mahekta R Gujar
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, 169857, Singapore
| | - Hongyan Wang
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, 8 College Road, 169857, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 117597, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, 117456, Singapore
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14
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Chuyen A, Daian F, Pasini A, Kodjabachian L. A live-imaging protocol to track cell movement in the Xenopus embryo. STAR Protoc 2021; 2:100928. [PMID: 34778847 PMCID: PMC8577151 DOI: 10.1016/j.xpro.2021.100928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Tracking individual cell movement during development is challenging, particularly in tissues subjected to major remodeling. Currently, most live imaging techniques in Xenopus are limited to tissue explants and/or to superficial cells. We describe here a protocol to track immature multiciliated cells (MCCs) moving within the inner epidermal layer of a whole embryo. In addition, we present a data processing protocol to uncouple the movements of individual cells from the coplanar drifts of the tissue in which they are embedded. For complete details on the use and execution of this protocol, please refer to Chuyen et al. (2021).
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Affiliation(s)
- Alexandre Chuyen
- Aix-Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Fabrice Daian
- Aix-Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Andrea Pasini
- Aix-Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Laurent Kodjabachian
- Aix-Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
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15
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Deng Q, Tan YS, Chew LY, Wang H. Msps governs acentrosomal microtubule assembly and reactivation of quiescent neural stem cells. EMBO J 2021; 40:e104549. [PMID: 34368973 PMCID: PMC8488572 DOI: 10.15252/embj.2020104549] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 07/05/2021] [Accepted: 07/09/2021] [Indexed: 12/11/2022] Open
Abstract
The ability of stem cells to switch between quiescence and proliferation is crucial for tissue homeostasis and regeneration. Drosophila quiescent neural stem cells (NSCs) extend a primary cellular protrusion from the cell body prior to their reactivation. However, the structure and function of this protrusion are not well established. Here, we show that in the protrusion of quiescent NSCs, microtubules are predominantly acentrosomal and oriented plus‐end‐out toward the tip of the primary protrusion. We have identified Mini Spindles (Msps)/XMAP215 as a key microtubule regulator in quiescent NSCs that governs NSC reactivation via regulating acentrosomal microtubule growth and orientation. We show that quiescent NSCs form membrane contact with the neuropil and E‐cadherin, a cell adhesion molecule, localizes to these NSC‐neuropil junctions. Msps and a plus‐end directed motor protein Kinesin‐2 promote NSC cell cycle re‐entry and target E‐cadherin to NSC‐neuropil contact during NSC reactivation. Together, this work establishes acentrosomal microtubule organization in the primary protrusion of quiescent NSCs and the Msps‐Kinesin‐2 pathway that governs NSC reactivation, in part, by targeting E‐cad to NSC‐neuropil contact sites.
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Affiliation(s)
- Qiannan Deng
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
| | - Ye Sing Tan
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
| | - Liang Yuh Chew
- Temasek Life Sciences Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Hongyan Wang
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, Singapore, Singapore.,NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, Singapore, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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Huang J, Gujar MR, Deng Q, Y Chia S, Li S, Tan P, Sung W, Wang H. Histone lysine methyltransferase Pr-set7/SETD8 promotes neural stem cell reactivation. EMBO Rep 2021; 22:e50994. [PMID: 33565211 PMCID: PMC8024890 DOI: 10.15252/embr.202050994] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 01/05/2021] [Accepted: 01/12/2021] [Indexed: 01/07/2023] Open
Abstract
The ability of neural stem cells (NSCs) to switch between quiescence and proliferation is crucial for brain development and homeostasis. Increasing evidence suggests that variants of histone lysine methyltransferases including KMT5A are associated with neurodevelopmental disorders. However, the function of KMT5A/Pr-set7/SETD8 in the central nervous system is not well established. Here, we show that Drosophila Pr-Set7 is a novel regulator of NSC reactivation. Loss of function of pr-set7 causes a delay in NSC reactivation and loss of H4K20 monomethylation in the brain. Through NSC-specific in vivo profiling, we demonstrate that Pr-set7 binds to the promoter region of cyclin-dependent kinase 1 (cdk1) and Wnt pathway transcriptional co-activator earthbound1/jerky (ebd1). Further validation indicates that Pr-set7 is required for the expression of cdk1 and ebd1 in the brain. Similar to Pr-set7, Cdk1 and Ebd1 promote NSC reactivation. Finally, overexpression of Cdk1 and Ebd1 significantly suppressed NSC reactivation defects observed in pr-set7-depleted brains. Therefore, Pr-set7 promotes NSC reactivation by regulating Wnt signaling and cell cycle progression. Our findings may contribute to the understanding of mammalian KMT5A/PR-SET7/SETD8 during brain development.
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Affiliation(s)
- Jiawen Huang
- Neuroscience & Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
| | - Mahekta R Gujar
- Neuroscience & Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
| | - Qiannan Deng
- Neuroscience & Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
| | - Sook Y Chia
- Neuroscience & Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
- Present address:
National Neuroscience InstituteSingaporeSingapore
| | - Song Li
- Neuroscience & Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
| | - Patrick Tan
- Genome Institute of SingaporeSingaporeSingapore
- Cancer & Stem Cell Biology ProgramDuke‐NUS Medical SchoolSingaporeSingapore
- Cellular and Molecular ResearchNational Cancer CentreSingaporeSingapore
- Cancer Science Institute of SingaporeNational University of SingaporeSingaporeSingapore
| | - Wing‐Kin Sung
- Genome Institute of SingaporeSingaporeSingapore
- Department of Computer ScienceNational University of SingaporeSingaporeSingapore
| | - Hongyan Wang
- Neuroscience & Behavioral Disorders ProgrammeDuke‐NUS Medical SchoolSingaporeSingapore
- Department of PhysiologyYong Loo Lin School of MedicineNational University of SingaporeSingaporeSingapore
- Integrative Sciences and Engineering ProgrammeNational University of SingaporeSingaporeSingapore
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