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Liu W, Li Q. Single-cell transcriptomics dissecting the development and evolution of nervous system in insects. CURRENT OPINION IN INSECT SCIENCE 2024; 63:101201. [PMID: 38608931 DOI: 10.1016/j.cois.2024.101201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 04/07/2024] [Accepted: 04/08/2024] [Indexed: 04/14/2024]
Abstract
Insects can display a vast repertoire of complex and adaptive behaviors crucial for survival and reproduction. Yet, how the neural circuits underlying insect behaviors are assembled throughout development and remodeled during evolution remains largely obscure. The advent of single-cell transcriptomics has opened new paths to illuminate these historically intractable questions. Insect behavior is governed by its brain, whose functional complexity is realized through operations across multiple levels, from the molecular and cellular to the circuit and organ. Single-cell transcriptomics enables dissecting brain functions across all these levels and allows tracking regulatory dynamics throughout development and under perturbation. In this review, we mainly focus on the achievements of single-cell transcriptomics in dissecting the molecular and cellular architectures of nervous systems in representative insects, then discuss its applications in tracking the developmental trajectory and functional evolution of insect brains.
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Affiliation(s)
- Weiwei Liu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China; Yunnan Key Laboratory of Biodiversity Information, Kunming, China.
| | - Qiye Li
- BGI Research, Shenzhen 518083, China; BGI Research, Wuhan 430074, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
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2
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Nguyen TH, Vicidomini R, Choudhury SD, Han TH, Maric D, Brody T, Serpe M. scRNA-seq data from the larval Drosophila ventral cord provides a resource for studying motor systems function and development. Dev Cell 2024; 59:1210-1230.e9. [PMID: 38569548 PMCID: PMC11078614 DOI: 10.1016/j.devcel.2024.03.016] [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] [Received: 06/27/2023] [Revised: 12/05/2023] [Accepted: 03/06/2024] [Indexed: 04/05/2024]
Abstract
The Drosophila larval ventral nerve cord (VNC) shares many similarities with the spinal cord of vertebrates and has emerged as a major model for understanding the development and function of motor systems. Here, we use high-quality scRNA-seq, validated by anatomical identification, to create a comprehensive census of larval VNC cell types. We show that the neural lineages that comprise the adult VNC are already defined, but quiescent, at the larval stage. Using fluorescence-activated cell sorting (FACS)-enriched populations, we separate all motor neuron bundles and link individual neuron clusters to morphologically characterized known subtypes. We discovered a glutamate receptor subunit required for basal neurotransmission and homeostasis at the larval neuromuscular junction. We describe larval glia and endorse the general view that glia perform consistent activities throughout development. This census represents an extensive resource and a powerful platform for future discoveries of cellular and molecular mechanisms in repair, regeneration, plasticity, homeostasis, and behavioral coordination.
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Affiliation(s)
| | | | | | | | - Dragan Maric
- Flow and Imaging Cytometry Core, NINDS, NIH, Bethesda, MD 20892, USA
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3
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Wang Y, Salazar RJ, Simonetta LT, Sorrentino V, Gatton TJ, Wu B, Vecsey CG, Carrillo RA. hkb is required for DIP-α expression and target recognition in the Drosophila neuromuscular circuit. Commun Biol 2024; 7:507. [PMID: 38678127 PMCID: PMC11055905 DOI: 10.1038/s42003-024-06184-8] [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] [Received: 07/19/2023] [Accepted: 04/11/2024] [Indexed: 04/29/2024] Open
Abstract
Our nervous system contains billions of neurons that form precise connections with each other through interactions between cell surface proteins. In Drosophila, the Dpr and DIP immunoglobulin protein subfamilies form homophilic or heterophilic interactions to instruct synaptic connectivity, synaptic growth, and cell survival. However, the upstream regulatory mechanisms of Dprs and DIPs are not clear. On the other hand, while transcription factors have been implicated in target recognition, their downstream cell surface proteins remain mostly unknown. We conduct an F1 dominant modifier genetic screen to identify regulators of Dprs and DIPs. We identify huckebein (hkb), a transcription factor previously implicated in target recognition of the dorsal Is motor neuron. We show that hkb genetically interacts with DIP-α and loss of hkb leads to complete removal of DIP-α expression specifically in dorsal Is motor neurons. We then confirm that this specificity is through the dorsal Is motor neuron specific transcription factor, even-skipped (eve), which acts downstream of hkb. Analysis of the genetic interaction between hkb and eve reveals that they act in the same pathway to regulate dorsal Is motor neuron connectivity. Our study provides insight into the transcriptional regulation of DIP-α and suggests that distinct regulatory mechanisms exist for the same CSP in different neurons.
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Affiliation(s)
- Yupu Wang
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA.
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA.
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, 20147, USA.
| | - Rio J Salazar
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
- Program in Cell and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Luciano T Simonetta
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
| | - Violet Sorrentino
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
| | - Terrence J Gatton
- Neuroscience Program, Skidmore College, 815 N. Broadway, Saratoga Springs, NY, 12866, USA
| | - Bill Wu
- Neuroscience Program, Skidmore College, 815 N. Broadway, Saratoga Springs, NY, 12866, USA
| | - Christopher G Vecsey
- Neuroscience Program, Skidmore College, 815 N. Broadway, Saratoga Springs, NY, 12866, USA
| | - Robert A Carrillo
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA.
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA.
- Program in Cell and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA.
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4
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Wang X, Zhai Y, Zheng H. Deciphering the cellular heterogeneity of the insect brain with single-cell RNA sequencing. INSECT SCIENCE 2024; 31:314-327. [PMID: 37702319 DOI: 10.1111/1744-7917.13270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 09/14/2023]
Abstract
Insects show highly complicated adaptive and sophisticated behaviors, including spatial orientation skills, learning ability, and social interaction. These behaviors are controlled by the insect brain, the central part of the nervous system. The tiny insect brain consists of millions of highly differentiated and interconnected cells forming a complex network. Decades of research has gone into an understanding of which parts of the insect brain possess particular behaviors, but exactly how they modulate these functional consequences needs to be clarified. Detailed description of the brain and behavior is required to decipher the complexity of cell types, as well as their connectivity and function. Single-cell RNA-sequencing (scRNA-seq) has emerged recently as a breakthrough technology to understand the transcriptome at cellular resolution. With scRNA-seq, it is possible to uncover the cellular heterogeneity of brain cells and elucidate their specific functions and state. In this review, we first review the basic structure of insect brains and the links to insect behaviors mainly focusing on learning and memory. Then the scRNA applications on insect brains are introduced by representative studies. Single-cell RNA-seq has allowed researchers to classify cell subpopulations within different insect brain regions, pinpoint single-cell developmental trajectories, and identify gene regulatory networks. These developments empower the advances in neuroscience and shed light on the intricate problems in understanding insect brain functions and behaviors.
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Affiliation(s)
- Xiaofei Wang
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Yifan Zhai
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- Key Laboratory of Natural Enemies Insects, Ministry of Agriculture and Rural Affairs, Jinan, China
- Shandong Provincial Engineering Technology Research Center on Biocontrol of Crops Diseases and In-sect Pests, Jinan, China
| | - Hao Zheng
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
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5
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Tonti E, Dell'Omo R, Filippelli M, Spadea L, Salati C, Gagliano C, Musa M, Zeppieri M. Exploring Epigenetic Modifications as Potential Biomarkers and Therapeutic Targets in Glaucoma. Int J Mol Sci 2024; 25:2822. [PMID: 38474069 DOI: 10.3390/ijms25052822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 02/23/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024] Open
Abstract
Glaucoma, a complex and multifactorial neurodegenerative disorder, is a leading cause of irreversible blindness worldwide. Despite significant advancements in our understanding of its pathogenesis and management, early diagnosis and effective treatment of glaucoma remain major clinical challenges. Epigenetic modifications, encompassing deoxyribonucleic acid (DNA) methylation, histone modifications, and non-coding RNAs, have emerged as critical regulators of gene expression and cellular processes. The aim of this comprehensive review focuses on the emerging field of epigenetics and its role in understanding the complex genetic and molecular mechanisms underlying glaucoma. The review will provide an overview of the pathophysiology of glaucoma, emphasizing the intricacies of intraocular pressure regulation, retinal ganglion cell dysfunction, and optic nerve damage. It explores how epigenetic modifications, such as DNA methylation and histone modifications, can influence gene expression, and how these mechanisms are implicated in glaucomatous neurodegeneration and contribute to glaucoma pathogenesis. The manuscript discusses evidence from both animal models and human studies, providing insights into the epigenetic alterations associated with glaucoma onset and progression. Additionally, it discusses the potential of using epigenetic modifications as diagnostic biomarkers and therapeutic targets for more personalized and targeted glaucoma treatment.
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Affiliation(s)
- Emanuele Tonti
- Eye Clinic, Policlinico Umberto I University Hospital, 00142 Rome, Italy
| | - Roberto Dell'Omo
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Via Francesco De Sanctis 1, 86100 Campobasso, Italy
| | - Mariaelena Filippelli
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Via Francesco De Sanctis 1, 86100 Campobasso, Italy
| | - Leopoldo Spadea
- Eye Clinic, Policlinico Umberto I University Hospital, 00142 Rome, Italy
| | - Carlo Salati
- Department of Ophthalmology, University Hospital of Udine, 33100 Udine, Italy
| | - Caterina Gagliano
- Faculty of Medicine and Surgery, University of Enna "Kore", Piazza dell'Università, 94100 Enna, Italy
- Eye Clinic, Catania University, San Marco Hospital, Viale Carlo Azeglio Ciampi, 95121 Catania, Italy
| | - Mutali Musa
- Department of Optometry, University of Benin, Benin City 300238, Nigeria
| | - Marco Zeppieri
- Department of Ophthalmology, University Hospital of Udine, 33100 Udine, Italy
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6
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Yin C, Morita T, Parrish JZ. A cell atlas of the larval Aedes aegypti ventral nerve cord. Neural Dev 2024; 19:2. [PMID: 38297398 PMCID: PMC10829479 DOI: 10.1186/s13064-023-00178-8] [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: 09/23/2023] [Accepted: 11/28/2023] [Indexed: 02/02/2024] Open
Abstract
Mosquito-borne diseases account for nearly 1 million human deaths annually, yet we have a limited understanding of developmental events that influence host-seeking behavior and pathogen transmission in mosquitoes. Mosquito-borne pathogens are transmitted during blood meals, hence adult mosquito behavior and physiology have been intensely studied. However, events during larval development shape adult traits, larvae respond to many of the same sensory cues as adults, and larvae are susceptible to infection by many of the same disease-causing agents as adults. Hence, a better understanding of larval physiology will directly inform our understanding of physiological processes in adults. Here, we use single cell RNA sequencing (scRNA-seq) to provide a comprehensive view of cellular composition in the Aedes aegypti larval ventral nerve cord (VNC), a central hub of sensory inputs and motor outputs which additionally controls multiple aspects of larval physiology. We identify more than 35 VNC cell types defined in part by neurotransmitter and neuropeptide expression. We also explore diversity among monoaminergic and peptidergic neurons that likely control key elements of larval physiology and developmental timing, and identify neuroblasts and immature neurons, providing a view of neuronal differentiation in the VNC. Finally, we find that larval cell composition, number, and position are preserved in the adult abdominal VNC, suggesting studies of larval VNC form and function will likely directly inform our understanding adult mosquito physiology. Altogether, these studies provide a framework for targeted analysis of VNC development and neuronal function in Aedes aegypti larvae.
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Affiliation(s)
- Chang Yin
- Department of Biology, University of Washington, Seattle, WA, 98195, USA
- Division of Education, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Takeshi Morita
- Division of Education, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA
- Laboratory of Neurogenetics and Behavior, The Rockefeller University, New York, NY, 10065, USA
- Howard Hughes Medical Institute, New York, NY, 10065, USA
| | - Jay Z Parrish
- Department of Biology, University of Washington, Seattle, WA, 98195, USA.
- Division of Education, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA.
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7
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Sun C, Shao Y, Iqbal J. Insect Insights at the Single-Cell Level: Technologies and Applications. Cells 2023; 13:91. [PMID: 38201295 PMCID: PMC10777908 DOI: 10.3390/cells13010091] [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] [Received: 11/22/2023] [Revised: 12/23/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Single-cell techniques are a promising way to unravel the complexity and heterogeneity of transcripts at the cellular level and to reveal the composition of different cell types and functions in a tissue or organ. In recent years, advances in single-cell RNA sequencing (scRNA-seq) have further changed our view of biological systems. The application of scRNA-seq in insects enables the comprehensive characterization of both common and rare cell types and cell states, the discovery of new cell types, and revealing how cell types relate to each other. The recent application of scRNA-seq techniques to insect tissues has led to a number of exciting discoveries. Here we provide an overview of scRNA-seq and its application in insect research, focusing on biological applications, current challenges, and future opportunities to make new discoveries with scRNA-seq in insects.
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Affiliation(s)
- Chao Sun
- Analysis Center of Agrobiology and Environmental Sciences, Zhejiang University, Hangzhou 310058, China;
| | - Yongqi Shao
- Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Junaid Iqbal
- Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
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8
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Wang Y, Salazar R, Simonetta L, Sorrentino V, Gatton TJ, Wu B, Vecsey CG, Carrillo RA. hkb is required for DIP-α expression and target recognition in the Drosophila neuromuscular circuit. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.15.562341. [PMID: 37905128 PMCID: PMC10614772 DOI: 10.1101/2023.10.15.562341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Our nervous system contains billions of neurons that form precise connections with each other through interactions between cell surface proteins (CSPs). In Drosophila, the Dpr and DIP immunoglobulin protein subfamilies form homophilic or heterophilic interactions to instruct synaptic connectivity, synaptic growth and cell survival. However, the upstream regulation and downstream signaling mechanisms of Dprs and DIPs are not clear. In the Drosophila larval neuromuscular system, DIP-α is expressed in the dorsal and ventral type-Is motor neurons (MNs). We conducted an F1 dominant modifier genetic screen to identify regulators of Dprs and DIPs. We found that the transcription factor, huckebein (hkb), genetically interacts with DIP-α and is important for target recognition specifically in the dorsal Is MN, but not the ventral Is MN. Loss of hkb led to complete removal of DIP-α expression. We then confirmed that this specificity is through the dorsal Is MN specific transcription factor, even-skipped (eve), which acts downstream of hkb. Genetic interaction between hkb and eve revealed that they act in the same pathway to regulate dorsal Is MN connectivity. Our study provides insight into the transcriptional regulation of DIP-α and suggests that distinct regulatory mechanisms exist for the same CSP in different neurons.
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Affiliation(s)
- Yupu Wang
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL 60637
- Neuroscience Institute, University of Chicago, Chicago, IL 60637
- Current address: Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147
- Co-first author
| | - Rio Salazar
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL 60637
- Neuroscience Institute, University of Chicago, Chicago, IL 60637
- Program in Cell and Molecular Biology, University of Chicago, Chicago, IL 60637
- Co-first author
| | - Luciano Simonetta
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL 60637
- Neuroscience Institute, University of Chicago, Chicago, IL 60637
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL 60637
| | - Violet Sorrentino
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL 60637
- Neuroscience Institute, University of Chicago, Chicago, IL 60637
- Current address: Molecular and Cell Biology Graduate Program, University of Washington, Seattle, Washington 98195
| | - Terrence J. Gatton
- Neuroscience Program, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866
| | - Bill Wu
- Neuroscience Program, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866
| | | | - Robert A. Carrillo
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL 60637
- Neuroscience Institute, University of Chicago, Chicago, IL 60637
- Program in Cell and Molecular Biology, University of Chicago, Chicago, IL 60637
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL 60637
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Ma D, Herndon N, Le JQ, Abruzzi KC, Zinn K, Rosbash M. Neural connectivity molecules best identify the heterogeneous clock and dopaminergic cell types in the Drosophila adult brain. SCIENCE ADVANCES 2023; 9:eade8500. [PMID: 36812309 PMCID: PMC9946362 DOI: 10.1126/sciadv.ade8500] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 01/26/2023] [Indexed: 05/25/2023]
Abstract
Our recent single-cell sequencing of most adult Drosophila circadian neurons indicated notable and unexpected heterogeneity. To address whether other populations are similar, we sequenced a large subset of adult brain dopaminergic neurons. Their gene expression heterogeneity is similar to that of clock neurons, i.e., both populations have two to three cells per neuron group. There was also unexpected cell-specific expression of neuron communication molecule messenger RNAs: G protein-coupled receptor or cell surface molecule (CSM) transcripts alone can define adult brain dopaminergic and circadian neuron cell type. Moreover, the adult expression of the CSM DIP-beta in a small group of clock neurons is important for sleep. We suggest that the common features of circadian and dopaminergic neurons are general, essential for neuronal identity and connectivity of the adult brain, and that these features underlie the complex behavioral repertoire of Drosophila.
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Affiliation(s)
- Dingbang Ma
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Nicholas Herndon
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Jasmine Quynh Le
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Katharine C. Abruzzi
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Kai Zinn
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Michael Rosbash
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454, USA
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Bhatia-Dey N, Csoka AB, Heinbockel T. Chemosensory Ability and Sensitivity in Health and Disease: Epigenetic Regulation and COVID-19. Int J Mol Sci 2023; 24:ijms24044179. [PMID: 36835589 PMCID: PMC9959623 DOI: 10.3390/ijms24044179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/13/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
Throughout the animal kingdom, our two chemical senses, olfaction and gustation, are defined by two primary factors: genomic architecture of the organisms and their living environment. During the past three years of the global COVID-19 pandemic, these two sensory modalities have drawn much attention at the basic science and clinical levels because of the strong association of olfactory and gustatory dysfunction with viral infection. Loss of our sense of smell alone, or together with a loss of taste, has emerged as a reliable indicator of COVID-19 infection. Previously, similar dysfunctions have been detected in a large cohort of patients with chronic conditions. The research focus remains on understanding the persistence of olfactory and gustatory disturbances in the post-infection phase, especially in cases with long-term effect of infection (long COVID). Also, both sensory modalities show consistent age-related decline in studies aimed to understand the pathology of neurodegenerative conditions. Some studies using classical model organisms show an impact on neural structure and behavior in offspring as an outcome of parental olfactory experience. The methylation status of specific odorant receptors, activated in parents, is passed on to the offspring. Furthermore, experimental evidence indicates an inverse correlation of gustatory and olfactory abilities with obesity. Such diverse lines of evidence emerging from basic and clinical research studies indicate a complex interplay of genetic factors, evolutionary forces, and epigenetic alterations. Environmental factors that regulate gustation and olfaction could induce epigenetic modulation. However, in turn, such modulation leads to variable effects depending on genetic makeup and physiological status. Therefore, a layered regulatory hierarchy remains active and is passed on to multiple generations. In the present review, we attempt to understand the experimental evidence that indicates variable regulatory mechanisms through multilayered and cross-reacting pathways. Our analytical approach will add to enhancement of prevailing therapeutic interventions and bring to the forefront the significance of chemosensory modalities for the evaluation and maintenance of long-term health.
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Abstract
Among the many wonders of nature, the sense of smell of the fly Drosophila melanogaster might seem, at first glance, of esoteric interest. Nevertheless, for over a century, the 'nose' of this insect has been an extraordinary system to explore questions in animal behaviour, ecology and evolution, neuroscience, physiology and molecular genetics. The insights gained are relevant for our understanding of the sensory biology of vertebrates, including humans, and other insect species, encompassing those detrimental to human health. Here, I present an overview of our current knowledge of D. melanogaster olfaction, from molecules to behaviours, with an emphasis on the historical motivations of studies and illustration of how technical innovations have enabled advances. I also highlight some of the pressing and long-term questions.
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Affiliation(s)
- Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
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12
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Scalzotto M, Ng R, Cruchet S, Saina M, Armida J, Su CY, Benton R. Pheromone sensing in Drosophila requires support cell-expressed Osiris 8. BMC Biol 2022; 20:230. [PMID: 36217142 PMCID: PMC9552441 DOI: 10.1186/s12915-022-01425-w] [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] [Received: 03/15/2022] [Accepted: 09/29/2022] [Indexed: 11/16/2022] Open
Abstract
Background The nose of most animals comprises multiple sensory subsystems, which are defined by the expression of different olfactory receptor families. Drosophila melanogaster antennae contain two morphologically and functionally distinct subsystems that express odorant receptors (Ors) or ionotropic receptors (Irs). Although these receptors have been thoroughly characterized in this species, the subsystem-specific expression and roles of other genes are much less well-understood. Results Here we generate subsystem-specific transcriptomic datasets to identify hundreds of genes, encoding diverse protein classes, that are selectively enriched in either Or or Ir subsystems. Using single-cell antennal transcriptomic data and RNA in situ hybridization, we find that most neuronal genes—other than sensory receptor genes—are broadly expressed within the subsystems. By contrast, we identify many non-neuronal genes that exhibit highly selective expression, revealing substantial molecular heterogeneity in the non-neuronal cellular components of the olfactory subsystems. We characterize one Or subsystem-specific non-neuronal molecule, Osiris 8 (Osi8), a conserved member of a large, insect-specific family of transmembrane proteins. Osi8 is expressed in the membranes of tormogen support cells of pheromone-sensing trichoid sensilla. Loss of Osi8 does not have obvious impact on trichoid sensillar development or basal neuronal activity, but abolishes high sensitivity responses to pheromone ligands. Conclusions This work identifies a new protein required for insect pheromone detection, emphasizes the importance of support cells in neuronal sensory functions, and provides a resource for future characterization of other olfactory subsystem-specific genes. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01425-w.
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Affiliation(s)
- Marta Scalzotto
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Renny Ng
- Neurobiology Section, Division of Biological Sciences, University of California San Diego, La Jolla, CA, 92093, USA
| | - Steeve Cruchet
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Michael Saina
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Jan Armida
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Chih-Ying Su
- Neurobiology Section, Division of Biological Sciences, University of California San Diego, La Jolla, CA, 92093, USA
| | - Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland.
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13
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Transcriptional profiling from whole embryos to single neuroblast lineages in Drosophila. Dev Biol 2022; 489:21-33. [PMID: 35660371 PMCID: PMC9805786 DOI: 10.1016/j.ydbio.2022.05.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/06/2022] [Accepted: 05/25/2022] [Indexed: 01/03/2023]
Abstract
Embryonic development results in the production of distinct tissue types, and different cell types within each tissue. A major goal of developmental biology is to uncover the "parts list" of cell types that comprise each organ. Here we perform single cell RNA sequencing (scRNA-seq) of the Drosophila embryo to identify the genes that characterize different cell and tissue types during development. We assay three different timepoints, revealing a coordinated change in gene expression within each tissue. Interestingly, we find that the elav and Mhc genes, whose protein products are widely used as markers for neurons and muscles, respectively, show broad pan-embryonic expression, indicating the importance of post-transcriptional regulation. We next focus on the central nervous system (CNS), where we identify genes whose expression is enriched at each stage of neuronal differentiation: from neural progenitors, called neuroblasts, to their immediate progeny ganglion mother cells (GMCs), followed by new-born neurons, young neurons, and the most mature neurons. Finally, we ask whether the clonal progeny of a single neuroblast (NB7-1) share a similar transcriptional identity. Surprisingly, we find that clonal identity does not lead to transcriptional clustering, showing that neurons within a lineage are diverse, and that neurons with a similar transcriptional profile (e.g. motor neurons, glia) are distributed among multiple neuroblast lineages. Although each lineage consists of diverse progeny, we were able to identify a previously uncharacterized gene, Fer3, as an excellent marker for the NB7-1 lineage. Within the NB7-1 lineage, neurons which share a temporal identity (e.g. Hunchback, Kruppel, Pdm, and Castor temporal transcription factors in the NB7-1 lineage) have shared transcriptional features, allowing for the identification of candidate novel temporal factors or targets of the temporal transcription factors. In conclusion, we have characterized the embryonic transcriptome for all major tissue types and for three stages of development, as well as the first transcriptomic analysis of a single, identified neuroblast lineage, finding a lineage-enriched transcription factor.
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14
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Dillon N, Cocanougher B, Sood C, Yuan X, Kohn AB, Moroz LL, Siegrist SE, Zlatic M, Doe CQ. Single cell RNA-seq analysis reveals temporally-regulated and quiescence-regulated gene expression in Drosophila larval neuroblasts. Neural Dev 2022; 17:7. [PMID: 36002894 PMCID: PMC9404614 DOI: 10.1186/s13064-022-00163-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/19/2022] [Indexed: 12/12/2022] Open
Abstract
The mechanisms that generate neural diversity during development remains largely unknown. Here, we use scRNA-seq methodology to discover new features of the Drosophila larval CNS across several key developmental timepoints. We identify multiple progenitor subtypes - both stem cell-like neuroblasts and intermediate progenitors - that change gene expression across larval development, and report on new candidate markers for each class of progenitors. We identify a pool of quiescent neuroblasts in newly hatched larvae and show that they are transcriptionally primed to respond to the insulin signaling pathway to exit from quiescence, including relevant pathway components in the adjacent glial signaling cell type. We identify candidate "temporal transcription factors" (TTFs) that are expressed at different times in progenitor lineages. Our work identifies many cell type specific genes that are candidates for functional roles, and generates new insight into the differentiation trajectory of larval neurons.
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Affiliation(s)
- Noah Dillon
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, OR, 97403, Eugene, USA
| | - Ben Cocanougher
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Chhavi Sood
- Department of Biology, University of Virginia, VA, 22904, Charlottesville, USA
| | - Xin Yuan
- Department of Biology, University of Virginia, VA, 22904, Charlottesville, USA
| | - Andrea B Kohn
- Whitney Laboratory for Marine Biosciences, University of Florida, FL, 32080, St. Augustine, USA
| | - Leonid L Moroz
- Whitney Laboratory for Marine Biosciences, University of Florida, FL, 32080, St. Augustine, USA
| | - Sarah E Siegrist
- Department of Biology, University of Virginia, VA, 22904, Charlottesville, USA
| | - Marta Zlatic
- MRC Laboratory of Molecular Biology, Dept of Zoology, University of Cambridge, Cambridge, UK.,Janelia Research Campus, VA, Ashburn, USA
| | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, OR, 97403, Eugene, USA.
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15
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Abstract
Many insect cells are encapsulated within the exoskeleton and cannot be dissociated intact, making them inaccessible to single-cell transcriptomic profiling. We have used single-nucleus RNA sequencing to extract transcriptomic information from multiple Drosophila tissues. Here, we describe procedures for the (1) dissociation of single nuclei, (2) isolation of single nuclei using two popular cell sorters, and (3) preparation of libraries for Smart-seq2 and 10× Genomics. This protocol enables generation of high-quality transcriptomes from single nuclei and can be applied to other species. For complete details on the use and execution of this protocol, please refer to McLaughlin et al. (2021) and Li et al. (2022).
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16
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Velten J, Gao X, Van Nierop y Sanchez P, Domsch K, Agarwal R, Bognar L, Paulsen M, Velten L, Lohmann I. Single‐cell RNA sequencing of motoneurons identifies regulators of synaptic wiring in
Drosophila
embryos. Mol Syst Biol 2022; 18:e10255. [PMID: 35225419 PMCID: PMC8883443 DOI: 10.15252/msb.202110255] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 01/28/2022] [Accepted: 02/07/2022] [Indexed: 12/14/2022] Open
Abstract
The correct wiring of neuronal circuits is one of the most complex processes in development, since axons form highly specific connections out of a vast number of possibilities. Circuit structure is genetically determined in vertebrates and invertebrates, but the mechanisms guiding each axon to precisely innervate a unique pre‐specified target cell are poorly understood. We investigated Drosophila embryonic motoneurons using single‐cell genomics, imaging, and genetics. We show that a cell‐specific combination of homeodomain transcription factors and downstream immunoglobulin domain proteins is expressed in individual cells and plays an important role in determining cell‐specific connections between differentiated motoneurons and target muscles. We provide genetic evidence for a functional role of five homeodomain transcription factors and four immunoglobulins in the neuromuscular wiring. Knockdown and ectopic expression of these homeodomain transcription factors induces cell‐specific synaptic wiring defects that are partly phenocopied by genetic modulations of their immunoglobulin targets. Taken together, our data suggest that homeodomain transcription factor and immunoglobulin molecule expression could be directly linked and function as a crucial determinant of neuronal circuit structure.
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Affiliation(s)
- Jessica Velten
- Department of Developmental Biology Centre for Organismal Studies (COS) Heidelberg Heidelberg Germany
- The Barcelona Institute of Science and Technology Centre for Genomic Regulation (CRG) Barcelona Spain
- Flow Cytometry Core Facility European Molecular Biology Laboratory (EMBL) Heidelberg Germany
| | - Xuefan Gao
- Department of Developmental Biology Centre for Organismal Studies (COS) Heidelberg Heidelberg Germany
| | | | - Katrin Domsch
- Department of Developmental Biology Centre for Organismal Studies (COS) Heidelberg Heidelberg Germany
- Developmental Biology Erlangen‐Nürnberg University Erlangen Germany
| | - Rashi Agarwal
- Department of Developmental Biology Centre for Organismal Studies (COS) Heidelberg Heidelberg Germany
| | - Lena Bognar
- Department of Developmental Biology Centre for Organismal Studies (COS) Heidelberg Heidelberg Germany
| | - Malte Paulsen
- Flow Cytometry Core Facility European Molecular Biology Laboratory (EMBL) Heidelberg Germany
| | - Lars Velten
- The Barcelona Institute of Science and Technology Centre for Genomic Regulation (CRG) Barcelona Spain
- Universitat Pompeu Fabra (UPF) Barcelona Spain
| | - Ingrid Lohmann
- Department of Developmental Biology Centre for Organismal Studies (COS) Heidelberg Heidelberg Germany
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17
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Mika K, Benton R. Olfactory Receptor Gene Regulation in Insects: Multiple Mechanisms for Singular Expression. Front Neurosci 2021; 15:738088. [PMID: 34602974 PMCID: PMC8481607 DOI: 10.3389/fnins.2021.738088] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 08/24/2021] [Indexed: 12/25/2022] Open
Abstract
The singular expression of insect olfactory receptors in specific populations of olfactory sensory neurons is fundamental to the encoding of odors in patterns of neuronal activity in the brain. How a receptor gene is selected, from among a large repertoire in the genome, to be expressed in a particular neuron is an outstanding question. Focusing on Drosophila melanogaster, where most investigations have been performed, but incorporating recent insights from other insect species, we review the multilevel regulatory mechanisms of olfactory receptor expression. We discuss how cis-regulatory elements, trans-acting factors, chromatin modifications, and feedback pathways collaborate to activate and maintain expression of the chosen receptor (and to suppress others), highlighting similarities and differences with the mechanisms underlying singular receptor expression in mammals. We also consider the plasticity of receptor regulation in response to environmental cues and internal state during the lifetime of an individual, as well as the evolution of novel expression patterns over longer timescales. Finally, we describe the mechanisms and potential significance of examples of receptor co-expression.
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Affiliation(s)
| | - Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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18
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Li H. Single-cell RNA sequencing in Drosophila: Technologies and applications. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2021; 10:e396. [PMID: 32940008 PMCID: PMC7960577 DOI: 10.1002/wdev.396] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/09/2020] [Accepted: 08/20/2020] [Indexed: 12/12/2022]
Abstract
Single-cell RNA sequencing (scRNA-seq) has emerged as a powerful tool for investigating cell states and functions at the single-cell level. It has greatly revolutionized transcriptomic studies in many life science research fields, such as neurobiology, immunology, and developmental biology. With the fast development of both experimental platforms and bioinformatics approaches over the past decade, scRNA-seq is becoming economically feasible and experimentally practical for many biomedical laboratories. Drosophila has served as an excellent model organism for dissecting cellular and molecular mechanisms that underlie tissue development, adult cell function, disease, and aging. The recent application of scRNA-seq methods to Drosophila tissues has led to a number of exciting discoveries. In this review, I will provide a summary of recent scRNA-seq studies in Drosophila, focusing on technical approaches and biological applications. I will also discuss current challenges and future opportunities of making new discoveries using scRNA-seq in Drosophila. This article is categorized under: Technologies > Analysis of the Transcriptome.
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Affiliation(s)
- Hongjie Li
- Department of Biology, Stanford University, Stanford, California, USA
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19
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Simon F, Konstantinides N. Single-cell transcriptomics in the Drosophila visual system: Advances and perspectives on cell identity regulation, connectivity, and neuronal diversity evolution. Dev Biol 2021; 479:107-122. [PMID: 34375653 DOI: 10.1016/j.ydbio.2021.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 07/10/2021] [Accepted: 08/03/2021] [Indexed: 11/17/2022]
Abstract
The Drosophila visual system supports complex behaviors and shares many of its anatomical and molecular features with the vertebrate brain. Yet, it contains a much more manageable number of neurons and neuronal types. In addition to the extensive Drosophila genetic toolbox, this relative simplicity has allowed decades of work to yield a detailed account of its neuronal type diversity, morphology, connectivity and specification mechanisms. In the past three years, numerous studies have applied large scale single-cell transcriptomic approaches to the Drosophila visual system and have provided access to the complete gene expression profile of most neuronal types throughout development. This makes the fly visual system particularly well suited to perform detailed studies of the genetic mechanisms underlying the evolution and development of neuronal systems. Here, we highlight how these transcriptomic resources allow exploring long-standing biological questions under a new light. We first present the efforts made to characterize neuronal diversity in the Drosophila visual system and suggest ways to further improve this description. We then discuss current advances allowed by the single-cell datasets, and envisage how these datasets can be further leveraged to address fundamental questions regarding the regulation of neuronal identity, neuronal circuit development and the evolution of neuronal diversity.
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Affiliation(s)
- Félix Simon
- Department of Biology, New York University, New York, NY, 10003, USA.
| | - Nikolaos Konstantinides
- Department of Biology, New York University, New York, NY, 10003, USA; Institut Jacques Monod, Centre National de la Recherche Scientifique-UMR 7592, Université Paris Diderot, Paris, France.
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20
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Mika K, Cruchet S, Chai PC, Prieto-Godino LL, Auer TO, Pradervand S, Benton R. Olfactory receptor-dependent receptor repression in Drosophila. SCIENCE ADVANCES 2021; 7:eabe3745. [PMID: 34362730 PMCID: PMC8346220 DOI: 10.1126/sciadv.abe3745] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 06/17/2021] [Indexed: 06/01/2023]
Abstract
In olfactory systems across phyla, most sensory neurons express a single olfactory receptor gene selected from a large genomic repertoire. We describe previously unknown receptor gene-dependent mechanisms that ensure singular expression of receptors encoded by a tandem gene array [Ionotropic receptor 75c (Ir75c), Ir75b, and Ir75a, organized 5' to 3'] in Drosophila melanogaster Transcription from upstream genes in the cluster runs through the coding region of downstream loci and inhibits their expression in cis, most likely via transcriptional interference. Moreover, Ir75c blocks accumulation of other receptor proteins in trans through a protein-dependent, posttranscriptional mechanism. These repression mechanisms operate in endogenous neurons, in conjunction with cell type-specific gene regulatory networks, to ensure unique receptor expression. Our data provide evidence for inter-olfactory receptor regulation in invertebrates and highlight unprecedented, but potentially widespread, mechanisms for ensuring exclusive expression of chemosensory receptors, and other protein families, encoded by tandemly arranged genes.
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Affiliation(s)
- Kaan Mika
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Steeve Cruchet
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Phing Chian Chai
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Lucia L Prieto-Godino
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Thomas O Auer
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Sylvain Pradervand
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
- Lausanne Genomic Technologies Facility, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
- Vital-IT Group, Swiss Institute of Bioinformatics, CH-1015 Lausanne, Switzerland
| | - Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland.
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21
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Arguello JR, Abuin L, Armida J, Mika K, Chai PC, Benton R. Targeted molecular profiling of rare olfactory sensory neurons identifies fate, wiring, and functional determinants. eLife 2021; 10:63036. [PMID: 33666172 PMCID: PMC7993999 DOI: 10.7554/elife.63036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 03/04/2021] [Indexed: 02/06/2023] Open
Abstract
Determining the molecular properties of neurons is essential to understand their development, function and evolution. Using Targeted DamID (TaDa), we characterize RNA polymerase II occupancy and chromatin accessibility in selected Ionotropic receptor (Ir)-expressing olfactory sensory neurons in Drosophila. Although individual populations represent a minute fraction of cells, TaDa is sufficiently sensitive and specific to identify the expected receptor genes. Unique Ir expression is not consistently associated with differences in chromatin accessibility, but rather to distinct transcription factor profiles. Genes that are heterogeneously expressed across populations are enriched for neurodevelopmental factors, and we identify functions for the POU-domain protein Pdm3 as a genetic switch of Ir neuron fate, and the atypical cadherin Flamingo in segregation of neurons into discrete glomeruli. Together this study reveals the effectiveness of TaDa in profiling rare neural populations, identifies new roles for a transcription factor and a neuronal guidance molecule, and provides valuable datasets for future exploration.
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Affiliation(s)
- J Roman Arguello
- Center for Integrative Genomics Faculty of Biology and Medicine University of Lausanne, Lausanne, Switzerland.,Department of Ecology and Evolution Faculty of Biology and Medicine University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Liliane Abuin
- Center for Integrative Genomics Faculty of Biology and Medicine University of Lausanne, Lausanne, Switzerland
| | - Jan Armida
- Center for Integrative Genomics Faculty of Biology and Medicine University of Lausanne, Lausanne, Switzerland
| | - Kaan Mika
- Center for Integrative Genomics Faculty of Biology and Medicine University of Lausanne, Lausanne, Switzerland
| | - Phing Chian Chai
- Center for Integrative Genomics Faculty of Biology and Medicine University of Lausanne, Lausanne, Switzerland
| | - Richard Benton
- Center for Integrative Genomics Faculty of Biology and Medicine University of Lausanne, Lausanne, Switzerland
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22
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McLaughlin CN, Brbić M, Xie Q, Li T, Horns F, Kolluru SS, Kebschull JM, Vacek D, Xie A, Li J, Jones RC, Leskovec J, Quake SR, Luo L, Li H. Single-cell transcriptomes of developing and adult olfactory receptor neurons in Drosophila. eLife 2021; 10:e63856. [PMID: 33555999 PMCID: PMC7870146 DOI: 10.7554/elife.63856] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 01/26/2021] [Indexed: 12/11/2022] Open
Abstract
Recognition of environmental cues is essential for the survival of all organisms. Transcriptional changes occur to enable the generation and function of the neural circuits underlying sensory perception. To gain insight into these changes, we generated single-cell transcriptomes of Drosophila olfactory- (ORNs), thermo-, and hygro-sensory neurons at an early developmental and adult stage using single-cell and single-nucleus RNA sequencing. We discovered that ORNs maintain expression of the same olfactory receptors across development. Using receptor expression and computational approaches, we matched transcriptomic clusters corresponding to anatomically and physiologically defined neuron types across multiple developmental stages. We found that cell-type-specific transcriptomes partly reflected axon trajectory choices in development and sensory modality in adults. We uncovered stage-specific genes that could regulate the wiring and sensory responses of distinct ORN types. Collectively, our data reveal transcriptomic features of sensory neuron biology and provide a resource for future studies of their development and physiology.
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Affiliation(s)
- Colleen N McLaughlin
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Maria Brbić
- Department of Computer Science, Stanford UniversityStanfordUnited States
| | - Qijing Xie
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
- Neurosciences Graduate Program, Stanford UniversityStanfordUnited States
| | - Tongchao Li
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Felix Horns
- Department of Bioengineering, Stanford UniversityStanfordUnited States
- Biophysics Graduate Program, Stanford UniversityStanfordUnited States
| | - Sai Saroja Kolluru
- Department of Bioengineering, Stanford UniversityStanfordUnited States
- Chan Zuckerberg BiohubStanfordUnited States
| | - Justus M Kebschull
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - David Vacek
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Anthony Xie
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Jiefu Li
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
- Biology Graduate Program, Stanford UniversityStanfordUnited States
| | - Robert C Jones
- Department of Bioengineering, Stanford UniversityStanfordUnited States
| | - Jure Leskovec
- Department of Computer Science, Stanford UniversityStanfordUnited States
| | - Stephen R Quake
- Department of Bioengineering, Stanford UniversityStanfordUnited States
- Chan Zuckerberg BiohubStanfordUnited States
- Department of Applied Physics, Stanford UniversityStanfordUnited States
| | - Liqun Luo
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Hongjie Li
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
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23
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Ma D, Przybylski D, Abruzzi KC, Schlichting M, Li Q, Long X, Rosbash M. A transcriptomic taxonomy of Drosophila circadian neurons around the clock. eLife 2021; 10:63056. [PMID: 33438579 PMCID: PMC7837698 DOI: 10.7554/elife.63056] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 01/11/2021] [Indexed: 01/19/2023] Open
Abstract
Many different functions are regulated by circadian rhythms, including those orchestrated by discrete clock neurons within animal brains. To comprehensively characterize and assign cell identity to the 75 pairs of Drosophila circadian neurons, we optimized a single-cell RNA sequencing method and assayed clock neuron gene expression at different times of day. The data identify at least 17 clock neuron categories with striking spatial regulation of gene expression. Transcription factor regulation is prominent and likely contributes to the robust circadian oscillation of many transcripts, including those that encode cell-surface proteins previously shown to be important for cell recognition and synapse formation during development. The many other clock-regulated genes also constitute an important resource for future mechanistic and functional studies between clock neurons and/or for temporal signaling to circuits elsewhere in the fly brain.
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Affiliation(s)
- Dingbang Ma
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
| | - Dariusz Przybylski
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
| | - Katharine C Abruzzi
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
| | | | - Qunlong Li
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
| | - Xi Long
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, United States
| | - Michael Rosbash
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
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24
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Xie Q, Brbic M, Horns F, Kolluru SS, Jones RC, Li J, Reddy AR, Xie A, Kohani S, Li Z, McLaughlin CN, Li T, Xu C, Vacek D, Luginbuhl DJ, Leskovec J, Quake SR, Luo L, Li H. Temporal evolution of single-cell transcriptomes of Drosophila olfactory projection neurons. eLife 2021; 10:e63450. [PMID: 33427646 PMCID: PMC7870145 DOI: 10.7554/elife.63450] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 01/05/2021] [Indexed: 12/18/2022] Open
Abstract
Neurons undergo substantial morphological and functional changes during development to form precise synaptic connections and acquire specific physiological properties. What are the underlying transcriptomic bases? Here, we obtained the single-cell transcriptomes of Drosophila olfactory projection neurons (PNs) at four developmental stages. We decoded the identity of 21 transcriptomic clusters corresponding to 20 PN types and developed methods to match transcriptomic clusters representing the same PN type across development. We discovered that PN transcriptomes reflect unique biological processes unfolding at each stage-neurite growth and pruning during metamorphosis at an early pupal stage; peaked transcriptomic diversity during olfactory circuit assembly at mid-pupal stages; and neuronal signaling in adults. At early developmental stages, PN types with adjacent birth order share similar transcriptomes. Together, our work reveals principles of cellular diversity during brain development and provides a resource for future studies of neural development in PNs and other neuronal types.
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Affiliation(s)
- Qijing Xie
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
- Neurosciences Graduate Program, Stanford UniversityStanfordUnited States
| | - Maria Brbic
- Department of Computer Science, Stanford UniversityStanfordUnited States
| | - Felix Horns
- Department of Bioengineering, Stanford UniversityStanfordUnited States
- Biophysics Graduate Program, Stanford UniversityStanfordUnited States
| | | | - Robert C Jones
- Department of Bioengineering, Stanford UniversityStanfordUnited States
| | - Jiefu Li
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Anay R Reddy
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Anthony Xie
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Sayeh Kohani
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Zhuoran Li
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Colleen N McLaughlin
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Tongchao Li
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Chuanyun Xu
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - David Vacek
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - David J Luginbuhl
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Jure Leskovec
- Department of Computer Science, Stanford UniversityStanfordUnited States
| | - Stephen R Quake
- Department of Bioengineering, Stanford UniversityStanfordUnited States
- Department of Applied Physics, Stanford UniversityStanfordUnited States
- Chan Zuckerberg BiohubStanfordUnited States
| | - Liqun Luo
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Hongjie Li
- Department of Biology, Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
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25
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Reprogramming to recover youthful epigenetic information and restore vision. Nature 2020; 588:124-129. [PMID: 33268865 PMCID: PMC7752134 DOI: 10.1038/s41586-020-2975-4] [Citation(s) in RCA: 334] [Impact Index Per Article: 83.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/22/2020] [Indexed: 02/07/2023]
Abstract
Ageing is a degenerative process that leads to tissue dysfunction and death. A proposed cause of ageing is the accumulation of epigenetic noise that disrupts gene expression patterns, leading to decreases in tissue function and regenerative capacity1–3. Changes to DNA methylation patterns over time form the basis of ageing clocks4, but whether older individuals retain the information needed to restore these patterns—and, if so, whether this could improve tissue function—is not known. Over time, the central nervous system (CNS) loses function and regenerative capacity5–7. Using the eye as a model CNS tissue, here we show that ectopic expression of Oct4 (also known as Pou5f1), Sox2 and Klf4 genes (OSK) in mouse retinal ganglion cells restores youthful DNA methylation patterns and transcriptomes, promotes axon regeneration after injury, and reverses vision loss in a mouse model of glaucoma and in aged mice. The beneficial effects of OSK-induced reprogramming in axon regeneration and vision require the DNA demethylases TET1 and TET2. These data indicate that mammalian tissues retain a record of youthful epigenetic information—encoded in part by DNA methylation—that can be accessed to improve tissue function and promote regeneration in vivo.
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26
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Kozma MT, Ngo-Vu H, Rump MT, Bobkov YV, Ache BW, Derby CD. Single cell transcriptomes reveal expression patterns of chemoreceptor genes in olfactory sensory neurons of the Caribbean spiny lobster, Panulirus argus. BMC Genomics 2020; 21:649. [PMID: 32962631 PMCID: PMC7510291 DOI: 10.1186/s12864-020-07034-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/27/2020] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Crustaceans express several classes of receptor genes in their antennules, which house olfactory sensory neurons (OSNs) and non-olfactory chemosensory neurons. Transcriptomics studies reveal that candidate chemoreceptor proteins include variant Ionotropic Receptors (IRs) including both co-receptor IRs and tuning IRs, Transient Receptor Potential (TRP) channels, Gustatory Receptors, epithelial sodium channels, and class A G-protein coupled receptors (GPCRs). The Caribbean spiny lobster, Panulirus argus, expresses in its antennules nearly 600 IRs, 17 TRP channels, 1 Gustatory Receptor, 7 epithelial sodium channels, 81 GPCRs, 6 G proteins, and dozens of enzymes in signaling pathways. However, the specific combinatorial expression patterns of these proteins in single sensory neurons are not known for any crustacean, limiting our understanding of how their chemosensory systems encode chemical quality. RESULTS The goal of this study was to use transcriptomics to describe expression patterns of chemoreceptor genes in OSNs of P. argus. We generated and analyzed transcriptomes from 7 single OSNs, some of which were shown to respond to a food odor, as well as an additional 7 multicell transcriptomes from preparations containing few (2-4), several (ca. 15), or many (ca. 400) OSNs. We found that each OSN expressed the same 2 co-receptor IRs (IR25a, IR93a) but not the other 2 antennular coIRs (IR8a, IR76b), 9-53 tuning IRs but only one to a few in high abundance, the same 5 TRP channels plus up to 5 additional TRPs, 12-17 GPCRs including the same 5 expressed in every single cell transcriptome, the same 3 G proteins plus others, many enzymes in the signaling pathways, but no Gustatory Receptors or epithelial sodium channels. The greatest difference in receptor expression among the OSNs was the identity of the tuning IRs. CONCLUSIONS Our results provide an initial view of the combinatorial expression patterns of receptor molecules in single OSNs in one species of decapod crustacean, including receptors directly involved in olfactory transduction and others likely involved in modulation. Our results also suggest differences in receptor expression in OSNs vs. other chemosensory neurons.
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Affiliation(s)
- Mihika T Kozma
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA
| | - Hanh Ngo-Vu
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA
| | - Matthew T Rump
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA
| | - Yuriy V Bobkov
- Whitney Laboratory, University of Florida, St. Augustine, Florida, 32084, USA
| | - Barry W Ache
- Whitney Laboratory, University of Florida, St. Augustine, Florida, 32084, USA
| | - Charles D Derby
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA.
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Sustentacular Cell Enwrapment of Olfactory Receptor Neuronal Dendrites: An Update. Genes (Basel) 2020; 11:genes11050493. [PMID: 32365880 PMCID: PMC7291085 DOI: 10.3390/genes11050493] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/23/2020] [Accepted: 04/27/2020] [Indexed: 12/12/2022] Open
Abstract
The pseudostratified olfactory epithelium (OE) may histologically appear relatively simple, but the cytological relations among its cell types, especially those between olfactory receptor neurons (ORNs) and olfactory sustentacular cells (OSCs), prove more complex and variable than previously believed. Adding to the complexity is the short lifespan, persistent neurogenesis, and continuous rewiring of the ORNs. Contrary to the common belief that ORN dendrites are mostly positioned between OSCs, recent findings indicate a sustentacular cell enwrapped configuration for a majority of mature ORN dendrites at the superficial layer of the OE. After vertically sprouting out from the borderlines between OSCs, most of the immature ORN dendrites undergo a process of sideways migration and terminal maturation to become completely invaginated into and enwrapped by OSCs. Trailing the course of the dendritic sideways migration is the mesodendrite (mesentery of the enwrapped dendrite) made of closely apposed, cell junction connected plasma membrane layers of neighboring folds of the host sustentacular cell. Only a minority of the mature ORN dendrites at the OE apical surface are found at the borderlines between OSCs (unwrapped). Below I give a brief update on the cytoarchitectonic relations between the ORNs and OSCs of the OE. Emphasis is placed on the enwrapment of ORN dendrites by OSCs, on the sideways migration of immature ORN dendrites after emerging from the OE surface, and on the terminal maturation of the ORNs. Functional implications of ORN dendrite enwrapment and a comparison with myelination or Remak’s bundling of axons or axodendrites in the central and peripheral nervous system are also discussed.
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