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Chu SY, Lai YW, Hsu TC, Lu TM, Yu HH. Isoforms of terminal selector Mamo control axon guidance during adult Drosophila memory center construction via Semaphorin-1a. Dev Biol 2024; 515:1-6. [PMID: 38906235 DOI: 10.1016/j.ydbio.2024.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 06/16/2024] [Accepted: 06/18/2024] [Indexed: 06/23/2024]
Abstract
In animals undergoing metamorphosis, the appearance of the nervous system is coincidently transformed by the morphogenesis of neurons. Such morphogenic alterations are exemplified in three types of intrinsic neurons in the Drosophila memory center. In contrast to the well-characterized remodeling of γ neurons, the morphogenesis of α/β and α'/β' neurons has not been adequately explored. Here, we show that mamo, a BTB-zinc finger transcription factor that acts as a terminal selector for α'/β' neurons, controls the formation of the correct axonal pattern of α'/β' neurons. Intriguingly, specific Mamo isoforms are preferentially expressed in α'/β' neurons to regulate the expression of axon guidance molecule Semaphorin-1a. This action directs proper axon guidance in α'/β' neurons, which is also crucial for wiring of α'/β' neurons with downstream neurons. Taken together, our results provide molecular insights into how neurons establish correct axonal patterns in circuitry assembly during adult memory center construction.
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Affiliation(s)
- Sao-Yu Chu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Yen-Wei Lai
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Tsai-Chi Hsu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Tsai-Ming Lu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Hung-Hsiang Yu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
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2
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Lin S. The making of the Drosophila mushroom body. Front Physiol 2023; 14:1091248. [PMID: 36711013 PMCID: PMC9880076 DOI: 10.3389/fphys.2023.1091248] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 01/02/2023] [Indexed: 01/14/2023] Open
Abstract
The mushroom body (MB) is a computational center in the Drosophila brain. The intricate neural circuits of the mushroom body enable it to store associative memories and process sensory and internal state information. The mushroom body is composed of diverse types of neurons that are precisely assembled during development. Tremendous efforts have been made to unravel the molecular and cellular mechanisms that build the mushroom body. However, we are still at the beginning of this challenging quest, with many key aspects of mushroom body assembly remaining unexplored. In this review, I provide an in-depth overview of our current understanding of mushroom body development and pertinent knowledge gaps.
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Liu W, Liang W, Xiong XP, Li JL, Zhou R. A circular RNA Edis-Relish-castor axis regulates neuronal development in Drosophila. PLoS Genet 2022; 18:e1010433. [PMID: 36301831 PMCID: PMC9612563 DOI: 10.1371/journal.pgen.1010433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 09/19/2022] [Indexed: 11/16/2022] Open
Abstract
Circular RNAs (circRNAs) are a new group of noncoding/regulatory RNAs that are particularly abundant in the nervous system, however, their physiological functions are underexplored. Here we report that the brain-enriched circular RNA Edis (Ect4-derived immune suppressor) plays an essential role in neuronal development in Drosophila. We show that depletion of Edis in vivo causes defects in axonal projection patterns of mushroom body (MB) neurons in the brain, as well as impaired locomotor activity and shortened lifespan of adult flies. In addition, we find that the castor gene, which encodes a transcription factor involved in neurodevelopment, is upregulated in Edis knockdown neurons. Notably, castor overexpression phenocopies Edis knockdown, and reducing castor levels suppresses the neurodevelopmental phenotypes in Edis-depleted neurons. Furthermore, chromatin immunoprecipitation analysis reveals that the transcription factor Relish, which plays a key role in regulating innate immunity signaling, occupies a pair of sites at the castor promoter, and that both sites are required for optimal castor gene activation by either immune challenge or Edis depletion. Lastly, Relish mutation and/or depletion can rescue both the castor gene hyperactivation phenotype and neuronal defects in Edis knockdown animals. We conclude that the circular RNA Edis acts through Relish and castor to regulate neuronal development.
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Affiliation(s)
- Wei Liu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Cancer and Blood Disorders Institute, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, United States of America
- Institute for Fundamental Biomedical Research, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, United States of America
| | - Weihong Liang
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Cancer and Blood Disorders Institute, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, United States of America
- Institute for Fundamental Biomedical Research, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, United States of America
| | - Xiao-Peng Xiong
- Tumor Initiation and Maintenance Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States of America
- Development, Aging and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States of America
| | - Jian-Liang Li
- Tumor Initiation and Maintenance Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States of America
- National Institute of Environmental Health Sciences, Durham, North Carolina, United States of America
| | - Rui Zhou
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Cancer and Blood Disorders Institute, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, United States of America
- Institute for Fundamental Biomedical Research, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, United States of America
- Tumor Initiation and Maintenance Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States of America
- Development, Aging and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States of America
- * E-mail:
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Semaphorin 1a-mediated dendritic wiring of the Drosophila mushroom body extrinsic neurons. Proc Natl Acad Sci U S A 2022; 119:e2111283119. [PMID: 35286204 PMCID: PMC8944846 DOI: 10.1073/pnas.2111283119] [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: 11/18/2022] Open
Abstract
The adult Drosophila mushroom body (MB) is one of the most extensively studied neural circuits. However, how its circuit organization is established during development is unclear. In this study, we provide an initial characterization of the assembly process of the extrinsic neurons (dopaminergic neurons and MB output neurons) that target the vertical MB lobes. We probe the cellular mechanisms guiding the neurite targeting of these extrinsic neurons and demonstrate that Semaphorin 1a is required in several MB output neurons for their dendritic innervations to three specific MB lobe zones. Our study reveals several intriguing molecular and cellular principles governing assembly of the MB circuit. The Drosophila mushroom body (MB) is composed of parallel axonal fibers from intrinsic Kenyon cells (KCs). The parallel fibers are bundled into five MB lobes innervated by extrinsic neurons, including dopaminergic neurons (DANs) and MB output neurons (MBONs) that project axons or dendrites to the MB lobes, respectively. Each DAN and MBON innervates specific regions in the lobes and collectively subdivides them into 15 zones. How such modular circuit architecture is established remains unknown. Here, we followed the development of the DANs and MBONs targeting the vertical lobes of the adult MB. We found that these extrinsic neurons innervate the lobes sequentially and their neurite arborizations in the MB lobe zones are independent of each other. Ablation of DAN axons or MBON dendrites in a zone had a minimal effect on other extrinsic neurites in the same or neighboring zones, suggesting that these neurons do not use tiling mechanisms to establish zonal borders. In contrast, KC axons are necessary for the development of extrinsic neurites. Dendrites of some vertical lobe-innervating MBONs were redirected to specific zones in the horizontal lobes when their normal target lobes were missing, indicating a hierarchical organization of guidance signals for the MBON dendrites. We show that Semaphorin 1a is required in MBONs to innervate three specific MB zones, and overexpression of semaphorin 1a is sufficient to redirect DAN dendrites to these zones. Our study provides an initial characterization of the cellular and molecular mechanisms underlying the assembly process of MB extrinsic neurons.
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Horch HW, Spicer SB, Low IIC, Joncas CT, Quenzer ED, Okoya H, Ledwidge LM, Fisher HP. Characterization of plexinA and two distinct semaphorin1a transcripts in the developing and adult cricket Gryllus bimaculatus. J Comp Neurol 2019; 528:687-702. [PMID: 31621906 DOI: 10.1002/cne.24790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/26/2019] [Accepted: 09/26/2019] [Indexed: 11/06/2022]
Abstract
Guidance cues act during development to guide growth cones to their proper targets in both the central and peripheral nervous systems. Experiments in many species indicate that guidance molecules also play important roles after development, though less is understood about their functions in the adult. The Semaphorin family of guidance cues, signaling through Plexin receptors, influences the development of both axons and dendrites in invertebrates. Semaphorin functions have been extensively explored in Drosophila melanogaster and some other Dipteran species, but little is known about their function in hemimetabolous insects. Here, we characterize sema1a and plexA in the cricket Gryllus bimaculatus. In fact, we found two distinct predicted Sema1a proteins in this species, Sema1a.1 and Sema1a.2, which shared only 48% identity at the amino acid level. We include a phylogenetic analysis that predicted that many other insect species, both holometabolous and hemimetabolous, express two Sema1a proteins as well. Finally, we used in situ hybridization to show that sema1a.1 and sema1a.2 expression patterns were spatially distinct in the embryo, and both roughly overlap with plexA. All three transcripts were also expressed in the adult brain, mainly in the mushroom bodies, though sema1a.2 was expressed most robustly. sema1a.2 was also expressed strongly in the adult thoracic ganglia while sema1a.1 was only weakly expressed and plexA was undetectable.
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Affiliation(s)
- Hadley W Horch
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Sara B Spicer
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Isabel I C Low
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Colby T Joncas
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Eleanor D Quenzer
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Hikmah Okoya
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Lisa M Ledwidge
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Harrison P Fisher
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
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Kang H, Zhao J, Jiang X, Li G, Huang W, Cheng H, Duan R. Drosophila Netrin-B controls mushroom body axon extension and regulates courtship-associated learning and memory of a Drosophila fragile X syndrome model. Mol Brain 2019; 12:52. [PMID: 31138234 PMCID: PMC6540430 DOI: 10.1186/s13041-019-0472-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 05/06/2019] [Indexed: 01/29/2023] Open
Abstract
Mushroom body (MB) is a prominent structure essential for olfactory learning and memory in the Drosophila brain. The development of the MB involves the appropriate guidance of axon lobes and sister axon branches. Appropriate guidance that accurately shapes MB development requires the integration of various guidance cues provided by a series of cell types, which guide axons to reach their final positions within the MB neuropils. Netrins are axonal guidance molecules that are conserved regulators of embryonic nerve cord patterning. However, whether they contribute to MB morphogenesis has not yet been evaluated. Here, we find that Netrin-B (NetB) is highly expressed in the MB lobes, regulating lobe length through genetic interactions with the receptors Frazzled and Uncoordinated-5 from 24 h after pupal formation onwards. We observe that overexpression of NetB causes severe β lobe fusion in the MB, which is similar to the MB defects seen in the Drosophila model of fragile X syndrome (FXS). Our results further show that fragile-X mental retardation protein FMRP inhibits the translational activity of human ortholog Netrin-1 (NTN1). Knock-down of NetB significantly rescues the MB defects and ameliorates deficits in the learning and memory in FXS model Drosophila. These results indicate a critical role for NetB in MB lobe extension and identify NetB as a novel target of FMRP which contributes to learning and memory.
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Affiliation(s)
- Huaixing Kang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Juan Zhao
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Xuan Jiang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Guangxu Li
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Wen Huang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Huili Cheng
- Changchun Children' Hospital, Changchun, 130000, Jilin, China.
| | - Ranhui Duan
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China. .,Hunan Key Laboratory of Medical Genetics, Central South University, Changsha, 410078, Hunan, China. .,Hunan Key Laboratory of Animal Models for Human Diseases, Central South University, Changsha, 410078, Hunan, China.
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DISCO interacting protein 2 determines direction of axon projection under the regulation of c-Jun N-terminal kinase in the Drosophila mushroom body. Biochem Biophys Res Commun 2017; 487:116-121. [DOI: 10.1016/j.bbrc.2017.04.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 04/07/2017] [Indexed: 11/21/2022]
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