1
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Ji S, Zhou X, Hoffmann JA. Toll-mediated airway homeostasis is essential for fly survival upon injection of RasV12-GFP oncogenic cells. Cell Rep 2024; 43:113677. [PMID: 38236774 DOI: 10.1016/j.celrep.2024.113677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/08/2023] [Accepted: 01/01/2024] [Indexed: 03/02/2024] Open
Abstract
Toll signaling is well known for its pivotal role in the host response against the invasion of external pathogens. Here, we investigate the potential involvement of Toll signaling in the intersection between the host and oncogenic cells. We show that loss of myeloid differentiation factor 88 (Myd88) leads to drastic fly death after the injection of RasV12-GFP oncogenic cells. Transcriptomic analyses show that challenging flies with oncogenic cells or bacteria leads to distinct inductions of Myd88-dependent genes. We note that downregulation of Myd88 in the tracheal system accounts for fly mortality, and ectopic tracheal complementation of Myd88 rescues the survival defect in Myd88 loss-of-function mutants following RasV12-GFP injection. Further, molecular and genetic evidence indicate that Toll signaling modulates fly resistance to RasV12-GFP cells through mediating airway function in a rolled-dependent manner. Collectively, our data indicate a critical role of Toll signaling in tracheal homeostasis and host survival after the injection of oncogenic cells.
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Affiliation(s)
- Shanming Ji
- Insect Models of Innate Immunity (M3I; 9022), Institute of Molecular and Cellular Biology, CNRS, 67084 Strasbourg, France
| | - Xiaojing Zhou
- Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Jules A Hoffmann
- Insect Models of Innate Immunity (M3I; 9022), Institute of Molecular and Cellular Biology, CNRS, 67084 Strasbourg, France; Institute for Advanced Study, University of Strasbourg, 67000 Strasbourg, France; Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China.
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2
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Zhang J, Tang T, Zhang R, Wen L, Deng X, Xu X, Yang W, Jin F, Cao Y, Lu Y, Yu XQ. Maintaining Toll signaling in Drosophila brain is required to sustain autophagy for dopamine neuron survival. iScience 2024; 27:108795. [PMID: 38292423 PMCID: PMC10825691 DOI: 10.1016/j.isci.2024.108795] [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: 03/04/2023] [Revised: 10/19/2023] [Accepted: 01/02/2024] [Indexed: 02/01/2024] Open
Abstract
Macroautophagy/autophagy is a conserved process in eukaryotic cells to degrade and recycle damaged intracellular components. Higher level of autophagy in the brain has been observed, and autophagy dysfunction has an impact on neuronal health, but the molecular mechanism is unclear. In this study, we showed that overexpression of Toll-1 and Toll-7 receptors, as well as active Spätzle proteins in Drosophila S2 cells enhanced autophagy, and Toll-1/Toll-7 activated autophagy was dependent on Tube-Pelle-PP2A. Interestingly, Toll-1 but not Toll-7 mediated autophagy was dMyd88 dependent. Importantly, we observed that loss of functions in Toll-1 and Toll-7 receptors and PP2A activity in flies decreased autophagy level, resulting in the loss of dopamine (DA) neurons and reduced fly motion. Our results indicated that proper activation of Toll-1 and Toll-7 pathways and PP2A activity in the brain are necessary to sustain autophagy level for DA neuron survival.
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Affiliation(s)
- Jie Zhang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
- Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, College of Plant Protection, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Ting Tang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Ruonan Zhang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
- Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, College of Plant Protection, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Liang Wen
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Xiaojuan Deng
- Guangdong Laboratory for Lingnan Modern Agriculture, Laboratory of Insect Molecular Biology and Biotechnology, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Xiaoxia Xu
- Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, College of Plant Protection, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Wanying Yang
- Guangdong Laboratory for Lingnan Modern Agriculture, Laboratory of Insect Molecular Biology and Biotechnology, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Fengliang Jin
- Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, College of Plant Protection, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Yang Cao
- Guangdong Laboratory for Lingnan Modern Agriculture, Laboratory of Insect Molecular Biology and Biotechnology, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Yuzhen Lu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Xiao-Qiang Yu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
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3
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Peterson J, Balogh Sivars K, Bianco A, Röper K. Toll-like receptor signalling via IRAK4 affects epithelial integrity and tightness through regulation of junctional tension. Development 2023; 150:dev201893. [PMID: 37997696 PMCID: PMC10753582 DOI: 10.1242/dev.201893] [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: 04/19/2023] [Accepted: 11/08/2023] [Indexed: 11/25/2023]
Abstract
Toll-like receptors (TLRs) in mammalian systems are well known for their role in innate immunity. In addition, TLRs also fulfil crucial functions outside immunity, including the dorsoventral patterning function of the original Toll receptor in Drosophila and neurogenesis in mice. Recent discoveries in flies suggested key roles for TLRs in epithelial cells in patterning of junctional cytoskeletal activity. Here, we address the function of TLRs and the downstream key signal transduction component IRAK4 in human epithelial cells. Using differentiated human Caco-2 cells as a model for the intestinal epithelium, we show that these cells exhibit baseline TLR signalling, as revealed by p-IRAK4, and that blocking IRAK4 function leads to a loss of epithelial tightness involving key changes at tight and adherens junctions, such as a loss of epithelial tension and changes in junctional actomyosin. Changes upon IRAK-4 inhibition are conserved in human bronchial epithelial cells. Knockdown of IRAK4 and certain TLRs phenocopies the inhibitor treatment. These data suggest a model whereby TLR receptors near epithelial junctions might be involved in a continuous sensing of the epithelial state to promote epithelial tightness and integrity.
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Affiliation(s)
- Jesse Peterson
- MRC-Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Kinga Balogh Sivars
- Oncology R&D, Precision Medicine and Biosamples, R&D, AstraZeneca, Pepparedsleden 1, Nova, Mölndal, SE-431 83, Sweden
| | - Ambra Bianco
- Clinical Pharmacology and Safety Sciences CPSS Oncology Safety, AstraZeneca, Darwin Building, Cambridge Science Park, Milton Road, Cambridge CB4 0WG, UK
| | - Katja Röper
- MRC-Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
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4
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Zang Y, Bashaw GJ. Systematic analysis of the Frazzled receptor interactome establishes previously unreported regulators of axon guidance. Development 2023; 150:dev201636. [PMID: 37526651 PMCID: PMC10445734 DOI: 10.1242/dev.201636] [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: 01/19/2023] [Accepted: 07/07/2023] [Indexed: 08/02/2023]
Abstract
The Netrin receptor Dcc and its Drosophila homolog Frazzled play crucial roles in diverse developmental process, including axon guidance. In Drosophila, Fra regulates midline axon guidance through a Netrin-dependent and a Netrin-independent pathway. However, what molecules regulate these distinct signaling pathways remain unclear. To identify Fra-interacting proteins, we performed affinity purification mass spectrometry to establish a neuronal-specific Fra interactome. In addition to known interactors of Fra and Dcc, including Netrin and Robo1, our screen identified 85 candidate proteins, the majority of which are conserved in humans. Many of these proteins are expressed in the ventral nerve cord, and gene ontology, pathway analysis and biochemical validation identified several previously unreported pathways, including the receptor tyrosine phosphatase Lar, subunits of the COP9 signalosome and Rho-5, a regulator of the metalloprotease Tace. Finally, genetic analysis demonstrates that these genes regulate axon guidance and may define as yet unknown signaling mechanisms for Fra and its vertebrate homolog Dcc. Thus, the Fra interactome represents a resource to guide future functional studies.
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Affiliation(s)
- Yixin Zang
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, 415 Curie Blvd, Philadelphia, PA, 19104, USA
| | - Greg J. Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, 415 Curie Blvd, Philadelphia, PA, 19104, USA
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5
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Ali Mohammadie Kojour M, Jang HA, Lee YS, Jo YH, Han YS. Innate Immune Response of TmToll-3 Following Systemic Microbial Infection in Tenebrio molitor. Int J Mol Sci 2023; 24:ijms24076751. [PMID: 37047723 PMCID: PMC10095136 DOI: 10.3390/ijms24076751] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 04/08/2023] Open
Abstract
Although Toll-like receptors have been widely identified and functionally characterized in mammalian models and Drosophila, the immunological function of these receptors in other insects remains unclear. Here, we explored the relevant innate immune response of Tenebrio molitor (T. molitor) Toll-3 against Gram-negative bacteria, Gram-positive bacteria, and fungal infections. Our findings indicated that TmToll-3 expression was mainly induced by Candida albicans infections in the fat bodies, gut, Malpighian tubules, and hemolymph of young T. molitor larvae. Surprisingly, Escherichia coli systemic infection caused mortality after TmToll-3 knockdown via RNA interference (RNAi) injection, which was not observed in the control group. Further analyses indicated that in the absence of TmToll-3, the final effector of the Toll signaling pathway, antimicrobial peptide (AMP) genes and relevant transcription factors were significantly downregulated after E. coli challenge. Our results indicated that the expression of almost all AMP genes was suppressed in silenced individuals, whereas the expression of relevant genes was positively regulated after fungal injection. Therefore, this study revealed the immunological involvement of TmToll-3 in T. molitor in response to systematic infections.
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Affiliation(s)
- Maryam Ali Mohammadie Kojour
- Department of Applied Biology, Institute of Environmentally-Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Ho Am Jang
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan 31538, Republic of Korea
| | - Yong Seok Lee
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan 31538, Republic of Korea
| | - Yong Hun Jo
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan 31538, Republic of Korea
| | - Yeon Soo Han
- Department of Applied Biology, Institute of Environmentally-Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea
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6
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Orús-Alcalde A, Børve A, Hejnol A. The localization of Toll and Imd pathway and complement system components and their response to Vibrio infection in the nemertean Lineus ruber. BMC Biol 2023; 21:7. [PMID: 36635688 PMCID: PMC9835746 DOI: 10.1186/s12915-022-01482-1] [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: 06/12/2022] [Accepted: 11/24/2022] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Innate immunity is the first line of defense against pathogens. In animals, the Toll pathway, the Imd pathway, the complement system, and lectins are well-known mechanisms involved in innate immunity. Although these pathways and systems are well understood in vertebrates and arthropods, they are understudied in other invertebrates. RESULTS To shed light on immunity in the nemertean Lineus ruber, we performed a transcriptomic survey and identified the main components of the Toll pathway (e.g., myD88, dorsal/dif/NFκB-p65), the Imd pathway (e.g., imd, relish/NFκB-p105/100), the complement system (e.g., C3, cfb), and some lectins (FreD-Cs and C-lectins). In situ hybridization showed that TLRβ1, TLRβ2, and imd are expressed in the nervous system; the complement gene C3-1 is expressed in the gut; and the lectins are expressed in the nervous system, the blood, and the gut. To reveal their potential role in defense mechanisms, we performed immune challenge experiments, in which Lineus ruber specimens were exposed to the gram-negative bacteria Vibrio diazotrophicus. Our results show the upregulation of specific components of the Toll pathway (TLRα3, TLRβ1, and TLRβ2), the complement system (C3-1), and lectins (c-lectin2 and fred-c5). CONCLUSIONS Therefore, similarly to what occurs in other invertebrates, our study shows that components of the Toll pathway, the complement system, and lectins are involved in the immune response in the nemertean Lineus ruber. The presence of these pathways and systems in Lineus ruber, but also in other spiralians; in ecdysozoans; and in deuterostomes suggests that these pathways and systems were involved in the immune response in the stem species of Bilateria.
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Affiliation(s)
- Andrea Orús-Alcalde
- grid.7914.b0000 0004 1936 7443Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5008 Bergen, Norway ,grid.7914.b0000 0004 1936 7443Department of Biological Sciences, University of Bergen, Thormøhlensgate 53A, 5006 Bergen, Norway
| | - Aina Børve
- grid.7914.b0000 0004 1936 7443Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5008 Bergen, Norway ,grid.7914.b0000 0004 1936 7443Department of Biological Sciences, University of Bergen, Thormøhlensgate 53A, 5006 Bergen, Norway
| | - Andreas Hejnol
- grid.7914.b0000 0004 1936 7443Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5008 Bergen, Norway ,grid.7914.b0000 0004 1936 7443Department of Biological Sciences, University of Bergen, Thormøhlensgate 53A, 5006 Bergen, Norway ,grid.9613.d0000 0001 1939 2794Faculty of Biological Sciences, Institute of Zoology and Evolutionary Research, Friedrich Schiller University Jena, Jena, Germany
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7
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Kong D, Zhao S, Xu W, Dong J, Ma X. Fat body-derived Spz5 remotely facilitates tumor-suppressive cell competition through Toll-6-α-Spectrin axis-mediated Hippo activation. Cell Rep 2022; 39:110980. [PMID: 35732124 DOI: 10.1016/j.celrep.2022.110980] [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: 01/07/2022] [Revised: 04/19/2022] [Accepted: 05/27/2022] [Indexed: 11/03/2022] Open
Abstract
Tumor-suppressive cell competition is an evolutionarily conserved process that selectively removes precancerous cells to maintain tissue homeostasis. Using the polarity-deficiency-induced cell competition model in Drosophila, we identify Toll-6, a Toll-like receptor family member, as a driver of tension-mediated cell competition through α-Spectrin (α-Spec)-Yorkie (Yki) cascade. Toll-6 aggregates along the boundary between wild-type and polarity-deficient clones, where Toll-6 physically interacts with the cytoskeleton network protein α-Spec to increase mechanical tension, resulting in actomyosin-dependent Hippo pathway activation and the elimination of scrib mutant cells. Furthermore, we show that Spz5 secreted from fat body, the key innate organ in fly, facilitates the elimination of scrib clones by binding to Toll-6. These findings uncover mechanisms by which fat bodies remotely regulate tumor-suppressive cell competition of polarity-deficient tumors through inter-organ crosstalk and identified the Toll-6-α-Spec axis as an essential guardian that prevents tumorigenesis via tension-mediated cell elimination.
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Affiliation(s)
- Du Kong
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Sihua Zhao
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Wenyan Xu
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Jinxi Dong
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Xianjue Ma
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, China.
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8
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Umetsu D. Cell mechanics and cell-cell recognition controls by Toll-like receptors in tissue morphogenesis and homeostasis. Fly (Austin) 2022; 16:233-247. [PMID: 35579305 PMCID: PMC9116419 DOI: 10.1080/19336934.2022.2074783] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Signal transduction by the Toll-like receptors (TLRs) is conserved and essential for innate immunity in metazoans. The founding member of the TLR family, Drosophila Toll-1, was initially identified for its role in dorsoventral axis formation in early embryogenesis. The Drosophila genome encodes nine TLRs that display dynamic expression patterns during development, suggesting their involvement in tissue morphogenesis and homeostasis. Recent progress on the developmental functions of TLRs beyond dorsoventral patterning has revealed not only their diverse functions in various biological processes, but also unprecedented molecular mechanisms in directly regulating cell mechanics and cell-cell recognition independent of the canonical signal transduction pathway involving transcriptional regulation of target genes. In this review, I feature and discuss the non-immune functions of TLRs in the control of epithelial tissue homeostasis, tissue morphogenesis, and cell-cell recognition between cell populations with different cell identities.
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Affiliation(s)
- Daiki Umetsu
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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9
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Shields A, Amcheslavsky A, Brown E, Lee TV, Nie Y, Tanji T, Ip YT, Bergmann A. Toll-9 interacts with Toll-1 to mediate a feedback loop during apoptosis-induced proliferation in Drosophila. Cell Rep 2022; 39:110817. [PMID: 35584678 PMCID: PMC9211775 DOI: 10.1016/j.celrep.2022.110817] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/25/2022] [Accepted: 04/22/2022] [Indexed: 11/30/2022] Open
Abstract
Drosophila Toll-1 and all mammalian Toll-like receptors regulate innate immunity. However, the functions of the remaining eight Toll-related proteins in Drosophila are not fully understood. Here, we show that Drosophila Toll-9 is necessary and sufficient for a special form of compensatory proliferation after apoptotic cell loss (undead apoptosis-induced proliferation [AiP]). Mechanistically, for AiP, Toll-9 interacts with Toll-1 to activate the intracellular Toll-1 pathway for nuclear translocation of the NF-κB-like transcription factor Dorsal, which induces expression of the pro-apoptotic genes reaper and hid. This activity contributes to the feedback amplification loop that operates in undead cells. Given that Toll-9 also functions in loser cells during cell competition, we define a general role of Toll-9 in cellular stress situations leading to the expression of pro-apoptotic genes that trigger apoptosis and apoptosis-induced processes such as AiP. This work identifies conceptual similarities between cell competition and AiP.
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Affiliation(s)
- Alicia Shields
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Alla Amcheslavsky
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Elizabeth Brown
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Tom V Lee
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yingchao Nie
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Takahiro Tanji
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Y Tony Ip
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Andreas Bergmann
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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10
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Xie Q, Li J, Li H, Udeshi ND, Svinkina T, Orlin D, Kohani S, Guajardo R, Mani DR, Xu C, Li T, Han S, Wei W, Shuster SA, Luginbuhl DJ, Quake SR, Murthy SE, Ting AY, Carr SA, Luo L. Transcription factor Acj6 controls dendrite targeting via a combinatorial cell-surface code. Neuron 2022; 110:2299-2314.e8. [PMID: 35613619 DOI: 10.1016/j.neuron.2022.04.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/11/2022] [Accepted: 04/26/2022] [Indexed: 12/13/2022]
Abstract
Transcription factors specify the fate and connectivity of developing neurons. We investigate how a lineage-specific transcription factor, Acj6, controls the precise dendrite targeting of Drosophila olfactory projection neurons (PNs) by regulating the expression of cell-surface proteins. Quantitative cell-surface proteomic profiling of wild-type and acj6 mutant PNs in intact developing brains, and a proteome-informed genetic screen identified PN surface proteins that execute Acj6-regulated wiring decisions. These include canonical cell adhesion molecules and proteins previously not associated with wiring, such as Piezo, whose mechanosensitive ion channel activity is dispensable for its function in PN dendrite targeting. Comprehensive genetic analyses revealed that Acj6 employs unique sets of cell-surface proteins in different PN types for dendrite targeting. Combined expression of Acj6 wiring executors rescued acj6 mutant phenotypes with higher efficacy and breadth than expression of individual executors. Thus, Acj6 controls wiring specificity of different neuron types by specifying distinct combinatorial expression of cell-surface executors.
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Affiliation(s)
- Qijing Xie
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Jiefu Li
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Hongjie Li
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Namrata D Udeshi
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Tanya Svinkina
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Daniel Orlin
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Sayeh Kohani
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Ricardo Guajardo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - D R Mani
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Chuanyun Xu
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Tongchao Li
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Shuo Han
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Wei Wei
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - S Andrew Shuster
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - David J Luginbuhl
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Stephen R Quake
- Departments of Bioengineering and Applied Physics, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Swetha E Murthy
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Alice Y Ting
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Steven A Carr
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Liqun Luo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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11
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Bando T, Okumura M, Bando Y, Hagiwara M, Hamada Y, Ishimaru Y, Mito T, Kawaguchi E, Inoue T, Agata K, Noji S, Ohuchi H. Toll signalling promotes blastema cell proliferation during cricket leg regeneration via insect macrophages. Development 2022; 149:272415. [PMID: 34622924 DOI: 10.1242/dev.199916] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 09/28/2021] [Indexed: 12/16/2022]
Abstract
Hemimetabolous insects, such as the two-spotted cricket Gryllus bimaculatus, can recover lost tissues, in contrast to the limited regenerative abilities of human tissues. Following cricket leg amputation, the wound surface is covered by the wound epidermis, and plasmatocytes, which are insect macrophages, accumulate in the wound region. Here, we studied the function of Toll-related molecules identified by comparative RNA sequencing during leg regeneration. Of the 11 Toll genes in the Gryllus genome, expression of Toll2-1, Toll2-2 and Toll2-5 was upregulated during regeneration. RNA interference (RNAi) of Toll, Toll2-1, Toll2-2, Toll2-3 or Toll2-4 produced regeneration defects in more than 50% of crickets. RNAi of Toll2-2 led to a decrease in the ratio of S- and M-phase cells, reduced expression of JAK/STAT signalling genes, and reduced accumulation of plasmatocytes in the blastema. Depletion of plasmatocytes in crickets using clodronate also produced regeneration defects, as well as fewer proliferating cells in the regenerating legs. Plasmatocyte depletion also downregulated the expression of Toll and JAK/STAT signalling genes in the regenerating legs. These results suggest that Spz-Toll-related signalling in plasmatocytes promotes leg regeneration through blastema cell proliferation by regulating the Upd-JAK/STAT signalling pathway.
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Affiliation(s)
- Tetsuya Bando
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama city, Okayama 700-8558, Japan
| | - Misa Okumura
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama city, Okayama 700-8558, Japan
| | - Yuki Bando
- Faculty of Medicine, Okayama University Medical School, 2-5-1, Shikata-cho, Kita-ku, Okayama city, Okayama 700-8558, Japan
| | - Marou Hagiwara
- Faculty of Medicine, Okayama University Medical School, 2-5-1, Shikata-cho, Kita-ku, Okayama city, Okayama 700-8558, Japan
| | - Yoshimasa Hamada
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama city, Okayama 700-8558, Japan
| | - Yoshiyasu Ishimaru
- Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Josanjima-cho, Tokushima City, Tokushima 770-8513, Japan
| | - Taro Mito
- Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Josanjima-cho, Tokushima City, Tokushima 770-8513, Japan
| | - Eri Kawaguchi
- Division of Biological Science, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan
| | - Takeshi Inoue
- Division of Biological Science, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan
| | - Kiyokazu Agata
- Division of Biological Science, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan
| | - Sumihare Noji
- Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Josanjima-cho, Tokushima City, Tokushima 770-8513, Japan
| | - Hideyo Ohuchi
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama city, Okayama 700-8558, Japan
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12
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Kamemura K, Moriya H, Ukita Y, Okumura M, Miura M, Chihara T. Endoplasmic reticulum proteins Meigo and Gp93 govern dendrite targeting by regulating Toll-6 localization. Dev Biol 2022; 484:30-39. [DOI: 10.1016/j.ydbio.2022.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 12/29/2021] [Accepted: 02/02/2022] [Indexed: 12/15/2022]
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13
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Derdeyn P, Hui M, Macchia D, Beier KT. Uncovering the Connectivity Logic of the Ventral Tegmental Area. Front Neural Circuits 2022; 15:799688. [PMID: 35153681 PMCID: PMC8832514 DOI: 10.3389/fncir.2021.799688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 12/14/2021] [Indexed: 11/13/2022] Open
Abstract
Decades of research have revealed the remarkable complexity of the midbrain dopamine (DA) system, which comprises cells principally located in the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). Neither homogenous nor serving a singular function, the midbrain DA system is instead composed of distinct cell populations that (1) receive different sets of inputs, (2) project to separate forebrain sites, and (3) are characterized by unique transcriptional and physiological signatures. To appreciate how these differences relate to circuit function, we first need to understand the anatomical connectivity of unique DA pathways and how this connectivity relates to DA-dependent motivated behavior. We and others have provided detailed maps of the input-output relationships of several subpopulations of midbrain DA cells and explored the roles of these different cell populations in directing behavioral output. In this study, we analyze VTA inputs and outputs as a high dimensional dataset (10 outputs, 22 inputs), deploying computational techniques well-suited to finding interpretable patterns in such data. In addition to reinforcing our previous conclusion that the connectivity in the VTA is dependent on spatial organization, our analysis also uncovered a set of inputs elevated onto each projection-defined VTADA cell type. For example, VTADA→NAcLat cells receive preferential innervation from inputs in the basal ganglia, while VTADA→Amygdala cells preferentially receive inputs from populations sending a distributed input across the VTA, which happen to be regions associated with the brain's stress circuitry. In addition, VTADA→NAcMed cells receive ventromedially biased inputs including from the preoptic area, ventral pallidum, and laterodorsal tegmentum, while VTADA→mPFC cells are defined by dominant inputs from the habenula and dorsal raphe. We also go on to show that the biased input logic to the VTADA cells can be recapitulated using projection architecture in the ventral midbrain, reinforcing our finding that most input differences identified using rabies-based (RABV) circuit mapping reflect projection archetypes within the VTA.
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Affiliation(s)
- Pieter Derdeyn
- Program in Mathematical, Computational, and Systems Biology, University of California, Irvine, Irvine, CA, United States
| | - May Hui
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
| | - Desiree Macchia
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
| | - Kevin T. Beier
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, United States
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, United States
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, United States
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14
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Ding X, Li Z, Lin G, Li W, Xue L. Toll-7 promotes tumour growth and invasion in Drosophila. Cell Prolif 2022; 55:e13188. [PMID: 35050535 PMCID: PMC8828261 DOI: 10.1111/cpr.13188] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 12/30/2021] [Accepted: 01/02/2022] [Indexed: 12/25/2022] Open
Abstract
Objectives Drosophila melanogaster has become an excellent model organism to explore the genetic mechanisms underlying tumour progression. Here, by using well‐established Drosophila tumour models, we identified Toll‐7 as a novel regulator of tumour growth and invasion. Materials and methods Transgenic flies and genetic epistasis analysis were used. All flies were raised on a standard cornmeal and agar medium at 25°C unless otherwise indicated. Immunostaining and RT‐qPCR were performed by standard procedures. Images were taken by OLYMPUS BX51 microscope and Zeiss LSM 880 confocal microscope. Adobe Photoshop 2020 and Zeiss Zen were used to analyse the images. All results were presented in Scatter plots or Column bar graphs created by GraphPad Prism 8.0. Results Loss of Toll‐7 suppresses RasV12/lgl−/−‐induced tumour growth and invasion, as well as cell polarity disruption‐induced invasive cell migration, whereas expression of a constitutively active allele of Toll‐7 is sufficient to promote tumorous growth and cell migration. In addition, the Egr‐JNK signalling is necessary and sufficient for Toll‐7‐induced invasive cell migration. Mechanistically, Toll‐7 facilitates the endocytosis of Egr, which is known to activate JNK in the early endosomes. Moreover, Toll‐7 activates the EGFR‐Ras signalling, which cooperates with the Egr‐JNK signalling to promote Yki‐mediated cell proliferation and tissue overgrowth. Finally, Toll‐7 is necessary and sufficient for the proper maintenance of EGFR protein level. Conclusions Our findings characterized Toll‐7 as a proto‐oncogene that promotes tumour growth and invasion in Drosophila, which shed light on the pro‐tumour function of mammalian Toll‐like receptors (TLRs).
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Affiliation(s)
- Xiang Ding
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Zhuojie Li
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Gufa Lin
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Wenzhe Li
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Lei Xue
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China.,Zhuhai Precision Medical Center, Zhuhai People's Hospital, Zhuhai Hospital Affiliated with Jinan University, Zhuhai, China
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15
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Orús-Alcalde A, Lu TM, Børve A, Hejnol A. The evolution of the metazoan Toll receptor family and its expression during protostome development. BMC Ecol Evol 2021; 21:208. [PMID: 34809567 PMCID: PMC8609888 DOI: 10.1186/s12862-021-01927-1] [Citation(s) in RCA: 6] [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: 02/02/2021] [Accepted: 10/21/2021] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Toll-like receptors (TLRs) play a crucial role in immunity and development. They contain leucine-rich repeat domains, one transmembrane domain, and one Toll/IL-1 receptor domain. TLRs have been classified into V-type/scc and P-type/mcc TLRs, based on differences in the leucine-rich repeat domain region. Although TLRs are widespread in animals, detailed phylogenetic studies of this gene family are lacking. Here we aim to uncover TLR evolution by conducting a survey and a phylogenetic analysis in species across Bilateria. To discriminate between their role in development and immunity we furthermore analyzed stage-specific transcriptomes of the ecdysozoans Priapulus caudatus and Hypsibius exemplaris, and the spiralians Crassostrea gigas and Terebratalia transversa. RESULTS We detected a low number of TLRs in ecdysozoan species, and multiple independent radiations within the Spiralia. V-type/scc and P-type/mcc type-receptors are present in cnidarians, protostomes and deuterostomes, and therefore they emerged early in TLR evolution, followed by a loss in xenacoelomorphs. Our phylogenetic analysis shows that TLRs cluster into three major clades: clade α is present in cnidarians, ecdysozoans, and spiralians; clade β in deuterostomes, ecdysozoans, and spiralians; and clade γ is only found in spiralians. Our stage-specific transcriptome and in situ hybridization analyses show that TLRs are expressed during development in all species analyzed, which indicates a broad role of TLRs during animal development. CONCLUSIONS Our findings suggest that a clade α TLR gene (TLR-Ca) and a clade β/γ TLR gene (TLR-Cβ/γ) were already present in the cnidarian-bilaterian common ancestor. However, although TLR-Ca was conserved in cnidarians, TLR-Cβ/γ was lost during the early evolution of these taxa. Moreover, TLR-Cβ/γ duplicated to generate TLR-Cβ and TLR-Cγ in the lineage to the last common protostome-deuterostome ancestor. TLR-Ca, TLR-Cβ and TLR-Cγ further expanded generating the three major TLR clades. While all three clades radiated in several spiralian lineages, specific TLRs clades have been presumably lost in other lineages. Furthermore, the expression of the majority of these genes during protostome ontogeny suggests a likely role in development.
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Affiliation(s)
- Andrea Orús-Alcalde
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5006, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Tsai-Ming Lu
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5006, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Aina Børve
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5006, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Andreas Hejnol
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5006, Bergen, Norway.
- Department of Biological Sciences, University of Bergen, Bergen, Norway.
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16
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COVID-19 Anosmia: High Prevalence, Plural Neuropathogenic Mechanisms, and Scarce Neurotropism of SARS-CoV-2? Viruses 2021; 13:v13112225. [PMID: 34835030 PMCID: PMC8625547 DOI: 10.3390/v13112225] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/28/2021] [Accepted: 10/30/2021] [Indexed: 12/14/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative pathogen of coronavirus disease 2019 (COVID-19). It is known as a respiratory virus, but SARS-CoV-2 appears equally, or even more, infectious for the olfactory epithelium (OE) than for the respiratory epithelium in the nasal cavity. In light of the small area of the OE relative to the respiratory epithelium, the high prevalence of olfactory dysfunctions (ODs) in COVID-19 has been bewildering and has attracted much attention. This review aims to first examine the cytological and molecular biological characteristics of the OE, especially the microvillous apical surfaces of sustentacular cells and the abundant SARS-CoV-2 receptor molecules thereof, that may underlie the high susceptibility of this neuroepithelium to SARS-CoV-2 infection and damages. The possibility of SARS-CoV-2 neurotropism, or the lack of it, is then analyzed with regard to the expression of the receptor (angiotensin-converting enzyme 2) or priming protease (transmembrane serine protease 2), and cellular targets of infection. Neuropathology of COVID-19 in the OE, olfactory bulb, and other related neural structures are also reviewed. Toward the end, we present our perspectives regarding possible mechanisms of SARS-CoV-2 neuropathogenesis and ODs, in the absence of substantial viral infection of neurons. Plausible causes for persistent ODs in some COVID-19 convalescents are also examined.
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17
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Li G, Hidalgo A. The Toll Route to Structural Brain Plasticity. Front Physiol 2021; 12:679766. [PMID: 34290618 PMCID: PMC8287419 DOI: 10.3389/fphys.2021.679766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/02/2021] [Indexed: 11/13/2022] Open
Abstract
The human brain can change throughout life as we learn, adapt and age. A balance between structural brain plasticity and homeostasis characterizes the healthy brain, and the breakdown of this balance accompanies brain tumors, psychiatric disorders, and neurodegenerative diseases. However, the link between circuit modifications, brain function, and behavior remains unclear. Importantly, the underlying molecular mechanisms are starting to be uncovered. The fruit-fly Drosophila is a very powerful model organism to discover molecular mechanisms and test them in vivo. There is abundant evidence that the Drosophila brain is plastic, and here we travel from the pioneering discoveries to recent findings and progress on molecular mechanisms. We pause on the recent discovery that, in the Drosophila central nervous system, Toll receptors—which bind neurotrophin ligands—regulate structural plasticity during development and in the adult brain. Through their topographic distribution across distinct brain modules and their ability to switch between alternative signaling outcomes, Tolls can enable the brain to translate experience into structural change. Intriguing similarities between Toll and mammalian Toll-like receptor function could reveal a further involvement in structural plasticity, degeneration, and disease in the human brain.
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Affiliation(s)
- Guiyi Li
- Plasticity and Regeneration Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Alicia Hidalgo
- Plasticity and Regeneration Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
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18
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Tamada M, Shi J, Bourdot KS, Supriyatno S, Palmquist KH, Gutierrez-Ruiz OL, Zallen JA. Toll receptors remodel epithelia by directing planar-polarized Src and PI3K activity. Dev Cell 2021; 56:1589-1602.e9. [PMID: 33932332 DOI: 10.1016/j.devcel.2021.04.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 03/11/2021] [Accepted: 04/07/2021] [Indexed: 12/12/2022]
Abstract
Toll-like receptors are essential for animal development and survival, with conserved roles in innate immunity, tissue patterning, and cell behavior. The mechanisms by which Toll receptors signal to the nucleus are well characterized, but how Toll receptors generate rapid, localized signals at the cell membrane to produce acute changes in cell polarity and behavior is not known. We show that Drosophila Toll receptors direct epithelial convergent extension by inducing planar-polarized patterns of Src and PI3-kinase (PI3K) activity. Toll receptors target Src activity to specific sites at the membrane, and Src recruits PI3K to the Toll-2 complex through tyrosine phosphorylation of the Toll-2 cytoplasmic domain. Reducing Src or PI3K activity disrupts planar-polarized myosin assembly, cell intercalation, and convergent extension, whereas constitutive Src activity promotes ectopic PI3K and myosin cortical localization. These results demonstrate that Toll receptors direct cell polarity and behavior by locally mobilizing Src and PI3K activity.
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Affiliation(s)
- Masako Tamada
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Jay Shi
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
| | - Kia S Bourdot
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Sara Supriyatno
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Karl H Palmquist
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Omar L Gutierrez-Ruiz
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Jennifer A Zallen
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA.
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19
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Lin TY, Chen PJ, Yu HH, Hsu CP, Lee CH. Extrinsic Factors Regulating Dendritic Patterning. Front Cell Neurosci 2021; 14:622808. [PMID: 33519386 PMCID: PMC7838386 DOI: 10.3389/fncel.2020.622808] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 12/17/2020] [Indexed: 12/18/2022] Open
Abstract
Stereotypic dendrite arborizations are key morphological features of neuronal identity, as the size, shape and location of dendritic trees determine the synaptic input fields and how information is integrated within developed neural circuits. In this review, we focus on the actions of extrinsic intercellular communication factors and their effects on intrinsic developmental processes that lead to dendrite patterning. Surrounding neurons or supporting cells express adhesion receptors and secreted proteins that respectively, act via direct contact or over short distances to shape, size, and localize dendrites during specific developmental stages. The different ligand-receptor interactions and downstream signaling events appear to direct dendrite morphogenesis by converging on two categorical mechanisms: local cytoskeletal and adhesion modulation and global transcriptional regulation of key dendritic growth components, such as lipid synthesis enzymes. Recent work has begun to uncover how the coordinated signaling of multiple extrinsic factors promotes complexity in dendritic trees and ensures robust dendritic patterning.
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Affiliation(s)
- Tzu-Yang Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Pei-Ju Chen
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Hung-Hsiang Yu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Chao-Ping Hsu
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chi-Hon Lee
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
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20
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Iijima N, Sato K, Kuranaga E, Umetsu D. Differential cell adhesion implemented by Drosophila Toll corrects local distortions of the anterior-posterior compartment boundary. Nat Commun 2020; 11:6320. [PMID: 33303753 PMCID: PMC7729853 DOI: 10.1038/s41467-020-20118-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/16/2020] [Indexed: 11/25/2022] Open
Abstract
Maintaining lineage restriction boundaries in proliferating tissues is vital to animal development. A long-standing thermodynamics theory, the differential adhesion hypothesis, attributes cell sorting phenomena to differentially expressed adhesion molecules. However, the contribution of the differential adhesion system during tissue morphogenesis has been unsubstantiated despite substantial theoretical support. Here, we report that Toll-1, a transmembrane receptor protein, acts as a differentially expressed adhesion molecule that straightens the fluctuating anteroposterior compartment boundary in the abdominal epidermal epithelium of the Drosophila pupa. Toll-1 is expressed across the entire posterior compartment under the control of the selector gene engrailed and displays a sharp expression boundary that coincides with the compartment boundary. Toll-1 corrects local distortions of the boundary in the absence of cable-like Myosin II enrichment along the boundary. The reinforced adhesion of homotypic cell contacts, together with pulsed cell contraction, achieves a biased vertex sliding action by resisting the separation of homotypic cell contacts in boundary cells. This work reveals a self-organizing system that integrates a differential adhesion system with pulsed contraction of cells to maintain lineage restriction boundaries.
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Affiliation(s)
- Norihiro Iijima
- Laboratory for Histogenetic Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Katsuhiko Sato
- Research Institute for Electronic Science, Hokkaido University, Sapporo, 001-0020, Japan
- Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, 001-0020, Japan
| | - Erina Kuranaga
- Laboratory for Histogenetic Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan.
| | - Daiki Umetsu
- Laboratory for Histogenetic Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan.
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21
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Valdes-Aleman J, Fetter RD, Sales EC, Heckman EL, Venkatasubramanian L, Doe CQ, Landgraf M, Cardona A, Zlatic M. Comparative Connectomics Reveals How Partner Identity, Location, and Activity Specify Synaptic Connectivity in Drosophila. Neuron 2020; 109:105-122.e7. [PMID: 33120017 PMCID: PMC7837116 DOI: 10.1016/j.neuron.2020.10.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 08/12/2020] [Accepted: 10/05/2020] [Indexed: 01/30/2023]
Abstract
The mechanisms by which synaptic partners recognize each other and establish appropriate numbers of connections during embryonic development to form functional neural circuits are poorly understood. We combined electron microscopy reconstruction, functional imaging of neural activity, and behavioral experiments to elucidate the roles of (1) partner identity, (2) location, and (3) activity in circuit assembly in the embryonic nerve cord of Drosophila. We found that postsynaptic partners are able to find and connect to their presynaptic partners even when these have been shifted to ectopic locations or silenced. However, orderly positioning of axon terminals by positional cues and synaptic activity is required for appropriate numbers of connections between specific partners, for appropriate balance between excitatory and inhibitory connections, and for appropriate functional connectivity and behavior. Our study reveals with unprecedented resolution the fine connectivity effects of multiple factors that work together to control the assembly of neural circuits.
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Affiliation(s)
- Javier Valdes-Aleman
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA; Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Richard D Fetter
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Emily C Sales
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Emily L Heckman
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | | | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Albert Cardona
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA; Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK; MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Marta Zlatic
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA; Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK; MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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22
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Ryba AR, McKenzie SK, Olivos-Cisneros L, Clowney EJ, Pires PM, Kronauer DJC. Comparative Development of the Ant Chemosensory System. Curr Biol 2020; 30:3223-3230.e4. [PMID: 32559450 DOI: 10.1016/j.cub.2020.05.072] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/24/2020] [Accepted: 05/21/2020] [Indexed: 12/15/2022]
Abstract
The insect antennal lobe (AL) contains the first synapses of the olfactory system, where olfactory sensory neurons (OSNs) contact second-order projection neurons (PNs). In Drosophila melanogaster, OSNs expressing specific receptor genes send stereotyped projections to one or two of about 50 morphologically defined glomeruli [1-3]. The mechanisms for this precise matching between OSNs and PNs have been studied extensively in D. melanogaster, where development is deterministic and independent of neural activity [4-6]. However, a number of insect lineages, most notably the ants, have receptor gene repertoires many times larger than D. melanogaster and exhibit more structurally complex antennal lobes [7-12]. Moreover, perturbation of OSN function via knockout of the odorant receptor (OR) co-receptor, Orco, results in drastic AL reductions in ants [13, 14], but not in Drosophila [15]. Here, we characterize AL development in the clonal raider ant, Ooceraea biroi. We find that, unlike in Drosophila, ORs and Orco are expressed before the onset of glomerulus formation, and Orco protein is trafficked to developing axon terminals, raising the possibility that ORs play a role during ant AL development. Additionally, ablating ant antennae at the onset of pupation results in AL defects that recapitulate the Orco mutant phenotype. Thus, early loss of functional OSN innervation reveals latent structure in the AL that develops independently of peripheral input, suggesting that the AL is initially pre-patterned and later refined in an OSN-dependent manner. This two-step process might increase developmental flexibility and thereby facilitate the rapid evolution and expansion of the ant chemosensory system.
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Affiliation(s)
- Anna R Ryba
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, NY 10065, USA
| | - Sean K McKenzie
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, NY 10065, USA; Department of Ecology and Evolution, University of Lausanne, Lausanne 1015, Switzerland
| | - Leonora Olivos-Cisneros
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, NY 10065, USA
| | - E Josephine Clowney
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Peter Mussells Pires
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, NY 10065, USA
| | - Daniel J C Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, NY 10065, USA.
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23
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Hörmann N, Schilling T, Ali AH, Serbe E, Mayer C, Borst A, Pujol-Martí J. A combinatorial code of transcription factors specifies subtypes of visual motion-sensing neurons in Drosophila. Development 2020; 147:223179. [PMID: 32238425 PMCID: PMC7240302 DOI: 10.1242/dev.186296] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/20/2020] [Indexed: 12/21/2022]
Abstract
Direction-selective T4/T5 neurons exist in four subtypes, each tuned to visual motion along one of the four cardinal directions. Along with their directional tuning, neurons of each T4/T5 subtype orient their dendrites and project their axons in a subtype-specific manner. Directional tuning, thus, appears strictly linked to morphology in T4/T5 neurons. How the four T4/T5 subtypes acquire their distinct morphologies during development remains largely unknown. Here, we investigated when and how the dendrites of the four T4/T5 subtypes acquire their specific orientations, and profiled the transcriptomes of all T4/T5 neurons during this process. This revealed a simple and stable combinatorial code of transcription factors defining the four T4/T5 subtypes during their development. Changing the combination of transcription factors of specific T4/T5 subtypes resulted in predictable and complete conversions of subtype-specific properties, i.e. dendrite orientation and matching axon projection pattern. Therefore, a combinatorial code of transcription factors coordinates the development of dendrite and axon morphologies to generate anatomical specializations that differentiate subtypes of T4/T5 motion-sensing neurons. Summary: Morphological and transcriptomic analyses allowed the identification of a combinatorial code of transcription factors that controls the development of subtype-specific morphologies in motion-detecting neurons of the Drosophila visual system.
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Affiliation(s)
- Nikolai Hörmann
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Tabea Schilling
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Aicha Haji Ali
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Etienne Serbe
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Christian Mayer
- Laboratory of Neurogenomics, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Alexander Borst
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Jesús Pujol-Martí
- Department of Circuits - Computation - Models, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
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24
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Sanes JR, Zipursky SL. Synaptic Specificity, Recognition Molecules, and Assembly of Neural Circuits. Cell 2020; 181:536-556. [DOI: 10.1016/j.cell.2020.04.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/23/2020] [Accepted: 04/06/2020] [Indexed: 01/02/2023]
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25
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Li H, Li T, Horns F, Li J, Xie Q, Xu C, Wu B, Kebschull JM, McLaughlin CN, Kolluru SS, Jones RC, Vacek D, Xie A, Luginbuhl DJ, Quake SR, Luo L. Single-Cell Transcriptomes Reveal Diverse Regulatory Strategies for Olfactory Receptor Expression and Axon Targeting. Curr Biol 2020; 30:1189-1198.e5. [PMID: 32059767 DOI: 10.1016/j.cub.2020.01.049] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/10/2020] [Accepted: 01/14/2020] [Indexed: 12/20/2022]
Abstract
The regulatory mechanisms by which neurons coordinate their physiology and connectivity are not well understood. The Drosophila olfactory receptor neurons (ORNs) provide an excellent system to investigate this question. Each ORN type expresses a unique olfactory receptor, or a combination thereof, and sends their axons to a stereotyped glomerulus. Using single-cell RNA sequencing, we identified 33 transcriptomic clusters for ORNs and mapped 20 to their glomerular types, demonstrating that transcriptomic clusters correspond well with anatomically and physiologically defined ORN types. Each ORN type expresses hundreds of transcription factors. Transcriptome-instructed genetic analyses revealed that (1) one broadly expressed transcription factor (Acj6) only regulates olfactory receptor expression in one ORN type and only wiring specificity in another type, (2) one type-restricted transcription factor (Forkhead) only regulates receptor expression, and (3) another type-restricted transcription factor (Unplugged) regulates both events. Thus, ORNs utilize diverse strategies and complex regulatory networks to coordinate their physiology and connectivity.
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Affiliation(s)
- Hongjie Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
| | - Tongchao Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Felix Horns
- Biophysics Graduate Program, Stanford University, Stanford, CA 94305, USA; Department of Bioengineering and Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Jiefu Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Qijing Xie
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Chuanyun Xu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Bing Wu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Justus M Kebschull
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Colleen N McLaughlin
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Sai Saroja Kolluru
- Department of Bioengineering and Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Robert C Jones
- Department of Bioengineering and Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - David Vacek
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Anthony Xie
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - David J Luginbuhl
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Stephen R Quake
- Department of Bioengineering and Department of Applied Physics, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, Stanford, CA 94305, USA.
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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26
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Li J, Han S, Li H, Udeshi ND, Svinkina T, Mani DR, Xu C, Guajardo R, Xie Q, Li T, Luginbuhl DJ, Wu B, McLaughlin CN, Xie A, Kaewsapsak P, Quake SR, Carr SA, Ting AY, Luo L. Cell-Surface Proteomic Profiling in the Fly Brain Uncovers Wiring Regulators. Cell 2020; 180:373-386.e15. [PMID: 31955847 DOI: 10.1016/j.cell.2019.12.029] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/17/2019] [Accepted: 12/19/2019] [Indexed: 01/12/2023]
Abstract
Molecular interactions at the cellular interface mediate organized assembly of single cells into tissues and, thus, govern the development and physiology of multicellular organisms. Here, we developed a cell-type-specific, spatiotemporally resolved approach to profile cell-surface proteomes in intact tissues. Quantitative profiling of cell-surface proteomes of Drosophila olfactory projection neurons (PNs) in pupae and adults revealed global downregulation of wiring molecules and upregulation of synaptic molecules in the transition from developing to mature PNs. A proteome-instructed in vivo screen identified 20 cell-surface molecules regulating neural circuit assembly, many of which belong to evolutionarily conserved protein families not previously linked to neural development. Genetic analysis further revealed that the lipoprotein receptor LRP1 cell-autonomously controls PN dendrite targeting, contributing to the formation of a precise olfactory map. These findings highlight the power of temporally resolved in situ cell-surface proteomic profiling in discovering regulators of brain wiring.
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Affiliation(s)
- Jiefu Li
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
| | - Shuo Han
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Hongjie Li
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Namrata D Udeshi
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Tanya Svinkina
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - D R Mani
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Chuanyun Xu
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Ricardo Guajardo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Qijing Xie
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Tongchao Li
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - David J Luginbuhl
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Bing Wu
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Colleen N McLaughlin
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Anthony Xie
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Pornchai Kaewsapsak
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Stephen R Quake
- Departments of Bioengineering and Applied Physics, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Steven A Carr
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Alice Y Ting
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA.
| | - Liqun Luo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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27
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Abstract
Convergent extension is a conserved mechanism for elongating tissues. In the Drosophila embryo, convergent extension is driven by planar polarized cell intercalation and is a paradigm for understanding the cellular, molecular, and biophysical mechanisms that establish tissue structure. Studies of convergent extension in Drosophila have provided key insights into the force-generating molecules that promote convergent extension in epithelial tissues, as well as the global systems of spatial information that systematically organize these cell behaviors. A general framework has emerged in which asymmetrically localized proteins involved in cytoskeletal tension and cell adhesion direct oriented cell movements, and spatial signals provided by the Toll, Tartan, and Teneurin receptor families break planar symmetry to establish and coordinate planar cell polarity throughout the tissue. In this chapter, we describe the cellular, molecular, and biophysical mechanisms that regulate cell intercalation in the Drosophila embryo, and discuss how research in this system has revealed conserved biological principles that control the organization of multicellular tissues and animal body plans.
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Affiliation(s)
- Adam C Paré
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, United States.
| | - Jennifer A Zallen
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, United States.
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28
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Elkahlah NA, Rogow JA, Ahmed M, Clowney EJ. Presynaptic developmental plasticity allows robust sparse wiring of the Drosophila mushroom body. eLife 2020; 9:e52278. [PMID: 31913123 PMCID: PMC7028369 DOI: 10.7554/elife.52278] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 01/07/2020] [Indexed: 01/29/2023] Open
Abstract
In order to represent complex stimuli, principle neurons of associative learning regions receive combinatorial sensory inputs. Density of combinatorial innervation is theorized to determine the number of distinct stimuli that can be represented and distinguished from one another, with sparse innervation thought to optimize the complexity of representations in networks of limited size. How the convergence of combinatorial inputs to principle neurons of associative brain regions is established during development is unknown. Here, we explore the developmental patterning of sparse olfactory inputs to Kenyon cells of the Drosophila melanogaster mushroom body. By manipulating the ratio between pre- and post-synaptic cells, we find that postsynaptic Kenyon cells set convergence ratio: Kenyon cells produce fixed distributions of dendritic claws while presynaptic processes are plastic. Moreover, we show that sparse odor responses are preserved in mushroom bodies with reduced cellular repertoires, suggesting that developmental specification of convergence ratio allows functional robustness.
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Affiliation(s)
- Najia A Elkahlah
- Department of Molecular, Cellular and Developmental BiologyThe University of MichiganAnn ArborUnited States
| | - Jackson A Rogow
- Laboratory of Neurophysiology and BehaviorThe Rockefeller UniversityNew YorkUnited States
| | - Maria Ahmed
- Department of Molecular, Cellular and Developmental BiologyThe University of MichiganAnn ArborUnited States
| | - E Josephine Clowney
- Department of Molecular, Cellular and Developmental BiologyThe University of MichiganAnn ArborUnited States
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29
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Chen CY, Shih YC, Hung YF, Hsueh YP. Beyond defense: regulation of neuronal morphogenesis and brain functions via Toll-like receptors. J Biomed Sci 2019; 26:90. [PMID: 31684953 PMCID: PMC6827257 DOI: 10.1186/s12929-019-0584-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 10/23/2019] [Indexed: 12/16/2022] Open
Abstract
Toll-like receptors (TLRs) are well known as critical pattern recognition receptors that trigger innate immune responses. In addition, TLRs are expressed in neurons and may act as the gears in the neuronal detection/alarm system for making good connections. As neuronal differentiation and circuit formation take place along with programmed cell death, neurons face the challenge of connecting with appropriate targets while avoiding dying or dead neurons. Activation of neuronal TLR3, TLR7 and TLR8 with nucleic acids negatively modulates neurite outgrowth and alters synapse formation in a cell-autonomous manner. It consequently influences neural connectivity and brain function and leads to deficits related to neuropsychiatric disorders. Importantly, neuronal TLR activation does not simply duplicate the downstream signal pathways and effectors of classical innate immune responses. The differences in spatial and temporal expression of TLRs and their ligands likely account for the diverse signaling pathways of neuronal TLRs. In conclusion, the accumulated evidence strengthens the idea that the innate immune system of neurons serves as an alarm system that responds to exogenous pathogens as well as intrinsic danger signals and fine-tune developmental processes of neurons.
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Affiliation(s)
- Chiung-Ya Chen
- Institute of Molecular Biology, Academia Sinica, 128, Academia Rd., Sec. 2, Taipei, 11529, Taiwan, Republic of China.
| | - Yi-Chun Shih
- Institute of Molecular Biology, Academia Sinica, 128, Academia Rd., Sec. 2, Taipei, 11529, Taiwan, Republic of China
| | - Yun-Fen Hung
- Institute of Molecular Biology, Academia Sinica, 128, Academia Rd., Sec. 2, Taipei, 11529, Taiwan, Republic of China
| | - Yi-Ping Hsueh
- Institute of Molecular Biology, Academia Sinica, 128, Academia Rd., Sec. 2, Taipei, 11529, Taiwan, Republic of China.
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30
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Paré AC, Naik P, Shi J, Mirman Z, Palmquist KH, Zallen JA. An LRR Receptor-Teneurin System Directs Planar Polarity at Compartment Boundaries. Dev Cell 2019; 51:208-221.e6. [PMID: 31495696 DOI: 10.1016/j.devcel.2019.08.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 04/25/2019] [Accepted: 08/02/2019] [Indexed: 12/28/2022]
Abstract
Epithelial cells dynamically self-organize in response to extracellular spatial cues relayed by cell-surface receptors. During convergent extension in Drosophila, Toll-related receptors direct planar polarized cell rearrangements that elongate the head-to-tail axis. However, many cells establish polarity in the absence of Toll receptor activity, indicating the presence of additional spatial cues. Here we demonstrate that the leucine-rich-repeat receptor Tartan and the teneurin Ten-m provide critical polarity signals at epithelial compartment boundaries. The Tartan and Ten-m extracellular domains interact in vitro, and Tartan promotes Ten-m localization to compartment boundaries in vivo. We show that Tartan and Ten-m are necessary for the planar polarity and organization of compartment boundary cells. Moreover, ectopic stripes of Tartan and Ten-m are sufficient to induce myosin accumulation at stripe boundaries. These results demonstrate that the Tartan/Ten-m and Toll receptor systems together create a high-resolution network of spatial cues that guides cell behavior during convergent extension.
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Affiliation(s)
- Adam C Paré
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Pooja Naik
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA; Weill Cornell Graduate School of Medical Sciences, New York, NY, USA
| | - Jay Shi
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
| | - Zachary Mirman
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Karl H Palmquist
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Jennifer A Zallen
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA.
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31
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Kim B. Evolutionarily conserved and divergent functions for cell adhesion molecules in neural circuit assembly. J Comp Neurol 2019; 527:2061-2068. [PMID: 30779135 DOI: 10.1002/cne.24666] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 02/11/2019] [Accepted: 02/11/2019] [Indexed: 12/17/2022]
Abstract
The developing nervous system generates remarkably precise synaptic connections between neurons and their postsynaptic target cells. Numerous neural cell adhesion proteins have been identified to mediate cell recognition between synaptic partners in several model organisms. Here, I review the role of protein interactions of cell adhesion molecules in neural circuit assembly and address how these interactions are utilized to form different neural circuitries in different species. The emerging evidence suggests that the extracellular trans-interactions of cell adhesion proteins for neural wiring are evolutionarily conserved across taxa, but they are often used in different steps of circuit assembly. I also highlight how these conserved protein interactions work together as a group to specify neural connectivity.
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Affiliation(s)
- Byunghyuk Kim
- Department of Life Science, Dongguk University Seoul, Goyang, Republic of Korea
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32
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Transsynaptic Fish-lips signaling prevents misconnections between nonsynaptic partner olfactory neurons. Proc Natl Acad Sci U S A 2019; 116:16068-16073. [PMID: 31341080 DOI: 10.1073/pnas.1905832116] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Our understanding of the mechanisms of neural circuit assembly is far from complete. Identification of wiring molecules with novel mechanisms of action will provide insights into how complex and heterogeneous neural circuits assemble during development. In the Drosophila olfactory system, 50 classes of olfactory receptor neurons (ORNs) make precise synaptic connections with 50 classes of partner projection neurons (PNs). Here, we performed an RNA interference screen for cell surface molecules and identified the leucine-rich repeat-containing transmembrane protein known as Fish-lips (Fili) as a novel wiring molecule in the assembly of the Drosophila olfactory circuit. Fili contributes to the precise axon and dendrite targeting of a small subset of ORN and PN classes, respectively. Cell-type-specific expression and genetic analyses suggest that Fili sends a transsynaptic repulsive signal to neurites of nonpartner classes that prevents their targeting to inappropriate glomeruli in the antennal lobe.
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33
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Shimozono M, Osaka J, Kato Y, Araki T, Kawamura H, Takechi H, Hakeda-Suzuki S, Suzuki T. Cell surface molecule, Klingon, mediates the refinement of synaptic specificity in the Drosophila visual system. Genes Cells 2019; 24:496-510. [PMID: 31124270 DOI: 10.1111/gtc.12703] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 05/04/2019] [Accepted: 05/19/2019] [Indexed: 11/29/2022]
Abstract
In the Drosophila brain, neurons form genetically specified synaptic connections with defined neuronal targets. It is proposed that each central nervous system neuron expresses specific cell surface proteins, which act as identification tags. Through an RNAi screen of cell surface molecules in the Drosophila visual system, we found that the cell adhesion molecule Klingon (Klg) plays an important role in repressing the ectopic formation of extended axons, preventing the formation of excessive synapses. Cell-specific manipulation of klg showed that Klg is required in both photoreceptors and the glia, suggesting that the balanced homophilic interaction between photoreceptor axons and the glia is required for normal synapse formation. Previous studies suggested that Klg binds to cDIP and our genetic analyses indicate that cDIP is required in glia for ectopic synaptic repression. These data suggest that Klg play a critical role together with cDIP in refining synaptic specificity and preventing unnecessary connections in the brain.
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Affiliation(s)
- Mai Shimozono
- Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Kanagawa, Japan
| | - Jiro Osaka
- Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Kanagawa, Japan
| | - Yuya Kato
- Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Kanagawa, Japan
| | - Tomohiro Araki
- Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Kanagawa, Japan
| | - Hinata Kawamura
- Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Kanagawa, Japan
| | - Hiroki Takechi
- Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Kanagawa, Japan
| | - Satoko Hakeda-Suzuki
- Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Kanagawa, Japan
| | - Takashi Suzuki
- Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Kanagawa, Japan
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34
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Yang CJ, Tsai KT, Liou NF, Chou YH. Interneuron Diversity: Toward a Better Understanding of Interneuron Development In the Olfactory System. J Exp Neurosci 2019; 13:1179069519826056. [PMID: 31001062 PMCID: PMC6454656 DOI: 10.1177/1179069519826056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/03/2019] [Indexed: 11/25/2022] Open
Abstract
The Drosophila olfactory system is an attractive model for
exploring the wiring logic of complex neural circuits. Remarkably, olfactory
local interneurons exhibit high diversity and variability in their morphologies
and intrinsic properties. Although olfactory sensory and projection neurons have
been extensively studied of development and wiring; the development, mechanisms
for establishing diversity, and integration of olfactory local interneurons into
the developing circuit remain largely undescribed. In this review, we discuss
some challenges and recent advances in the study of Drosophila
olfactory interneurons.
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Affiliation(s)
| | | | | | - Ya-Hui Chou
- Ya-Hui Chou, Institute of Cellular and
Organismic Biology, Academia Sinica, 128, Section 2, Academia Road, Nankang,
Taipei, Taiwan.
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35
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Park S, Jo YH, Park KB, Ko HJ, Kim CE, Bae YM, Kim B, Jun SA, Bang IS, Lee YS, Kim YJ, Han YS. TmToll-7 Plays a Crucial Role in Innate Immune Responses Against Gram-Negative Bacteria by Regulating 5 AMP Genes in Tenebrio molitor. Front Immunol 2019; 10:310. [PMID: 30930888 PMCID: PMC6424196 DOI: 10.3389/fimmu.2019.00310] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 02/06/2019] [Indexed: 11/22/2022] Open
Abstract
Although it is known that the Drosophila Toll-7 receptor plays a critical role in antiviral autophagy, its function in other insects has not yet been reported. Here, we have identified a Toll-like receptor 7 gene, TmToll-7, in the coleopteran insect T. molitor and examined its potential role in antibacterial and antifungal immunity. We showed that TmToll-7 expression was significantly induced in larvae 6 h after infection with Escherichia coli and Staphylococcus aureus and 9 h after infection with Candida albicans. However, even though TmToll-7 was induced by all three pathogens, we found that TmToll-7 knockdown significantly reduced larval survival to E. coli, but not to S. aureus, and C. albicans infections. To understand the reasons for this difference, we examined the effects of TmToll-7 knockdown on antimicrobial peptide (AMP) gene expression and found a significant reduction of E. coli-induced expression of AMP genes such as TmTenecin-1, TmDefensin-1, TmDefensin-2, TmColeoptericin-1, and TmAttacin-2. Furthermore, TmToll-7 knockdown larvae infected with E. coli showed significantly higher bacterial growth in the hemolymph compared to control larvae treated with Vermilion dsRNA. Taken together, our results suggest that TmToll-7 plays an important role in regulating the immune response of T. molitor to E. coli.
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Affiliation(s)
- Soyi Park
- Division of Plant Biotechnology, College of Agriculture and Life Sciences, Institute of Environmentally-Friendly Agriculture Chonnam National University, Gwangju, South Korea
| | - Yong Hun Jo
- Division of Plant Biotechnology, College of Agriculture and Life Sciences, Institute of Environmentally-Friendly Agriculture Chonnam National University, Gwangju, South Korea
| | - Ki Beom Park
- Division of Plant Biotechnology, College of Agriculture and Life Sciences, Institute of Environmentally-Friendly Agriculture Chonnam National University, Gwangju, South Korea
| | - Hye Jin Ko
- Division of Plant Biotechnology, College of Agriculture and Life Sciences, Institute of Environmentally-Friendly Agriculture Chonnam National University, Gwangju, South Korea
| | - Chang Eun Kim
- Division of Plant Biotechnology, College of Agriculture and Life Sciences, Institute of Environmentally-Friendly Agriculture Chonnam National University, Gwangju, South Korea
| | - Young Min Bae
- Division of Plant Biotechnology, College of Agriculture and Life Sciences, Institute of Environmentally-Friendly Agriculture Chonnam National University, Gwangju, South Korea
| | - Bobae Kim
- Division of Plant Biotechnology, College of Agriculture and Life Sciences, Institute of Environmentally-Friendly Agriculture Chonnam National University, Gwangju, South Korea
| | - Sung Ah Jun
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - In Seok Bang
- Department of Biological Science, Hoseo University, Asan, South Korea
| | - Yong Seok Lee
- Department of Life Science and Biotechnology, College of Natural Sciences, Soonchunhyang University, Asan, South Korea
| | - Yu Jung Kim
- Department of Chemistry and Biochemistry, College of Natural Sciences, California State University, San Bernardino, CA, United States
| | - Yeon Soo Han
- Division of Plant Biotechnology, College of Agriculture and Life Sciences, Institute of Environmentally-Friendly Agriculture Chonnam National University, Gwangju, South Korea
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36
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McLaughlin CN, Perry-Richardson JJ, Coutinho-Budd JC, Broihier HT. Dying Neurons Utilize Innate Immune Signaling to Prime Glia for Phagocytosis during Development. Dev Cell 2019; 48:506-522.e6. [PMID: 30745142 DOI: 10.1016/j.devcel.2018.12.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 11/19/2018] [Accepted: 12/21/2018] [Indexed: 02/06/2023]
Abstract
Glia continuously survey neuronal health during development, providing trophic support to healthy neurons while rapidly engulfing dying ones. These diametrically opposed functions necessitate a foolproof mechanism enabling glia to unambiguously identify those neurons to support versus those to engulf. To ensure specificity, glia are proposed to interact with dying neurons via a series of carefully choreographed steps. However, these crucial interactions are largely obscure. Here we show that dying neurons and glia communicate via Toll-receptor-regulated innate immune signaling. Neuronal apoptosis drives processing and activation of the Toll-6 ligand, Spätzle5. This cue activates a dSARM-mediated Toll-6 transcriptional pathway in glia, which controls the expression of the Draper engulfment receptor. Pathway loss drives early-onset neurodegeneration, underscoring its functional importance. Our results identify an upstream priming signal that prepares glia for phagocytosis. Thus, a core innate immune pathway plays an unprecedented role setting the valence of neuron-glia interactions during development.
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Affiliation(s)
- Colleen N McLaughlin
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
| | - Jahci J Perry-Richardson
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | | | - Heather T Broihier
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
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37
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DePew AT, Aimino MA, Mosca TJ. The Tenets of Teneurin: Conserved Mechanisms Regulate Diverse Developmental Processes in the Drosophila Nervous System. Front Neurosci 2019; 13:27. [PMID: 30760977 PMCID: PMC6363694 DOI: 10.3389/fnins.2019.00027] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 01/11/2019] [Indexed: 01/26/2023] Open
Abstract
To successfully integrate a neuron into a circuit, a myriad of developmental events must occur correctly and in the correct order. Neurons must be born and grow out toward a destination, responding to guidance cues to direct their path. Once arrived, each neuron must segregate to the correct sub-region before sorting through a milieu of incorrect partners to identify the correct partner with which they can connect. Finally, the neuron must make a synaptic connection with their correct partner; a connection that needs to be broadly maintained throughout the life of the animal while remaining responsive to modes of plasticity and pruning. Though many intricate molecular mechanisms have been discovered to regulate each step, recent work showed that a single family of proteins, the Teneurins, regulates a host of these developmental steps in Drosophila – an example of biological adaptive reuse. Teneurins first influence axon guidance during early development. Once neurons arrive in their target regions, Teneurins enable partner matching and synapse formation in both the central and peripheral nervous systems. Despite these diverse processes and systems, the Teneurins use conserved mechanisms to achieve these goals, as defined by three tenets: (1) transsynaptic interactions with each other, (2) membrane stabilization via an interaction with and regulation of the cytoskeleton, and (3) a role for presynaptic Ten-a in regulating synaptic function. These processes are further distinguished by (1) the nature of the transsynaptic interaction – homophilic interactions (between the same Teneurins) to engage partner matching and heterophilic interactions (between different Teneurins) to enable synaptic connectivity and the proper apposition of pre- and postsynaptic sites and (2) the location of cytoskeletal regulation (presynaptic cytoskeletal regulation in the CNS and postsynaptic regulation of the cytoskeleton at the NMJ). Thus, both the roles and the mechanisms governing them are conserved across processes and synapses. Here, we will highlight the contributions of Drosophila synaptic biology to our understanding of the Teneurins, discuss the mechanistic conservation that allows the Teneurins to achieve common neurodevelopmental goals, and present new data in support of these points. Finally, we will posit the next steps for understanding how this remarkably versatile family of proteins functions to control multiple distinct events in the creation of a nervous system.
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Affiliation(s)
- Alison T DePew
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, United States
| | - Michael A Aimino
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, United States
| | - Timothy J Mosca
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, United States
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38
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Kennedy T, Broadie K. Newly Identified Electrically Coupled Neurons Support Development of the Drosophila Giant Fiber Model Circuit. eNeuro 2018; 5:ENEURO.0346-18.2018. [PMID: 30627638 PMCID: PMC6325540 DOI: 10.1523/eneuro.0346-18.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/29/2018] [Accepted: 11/12/2018] [Indexed: 12/31/2022] Open
Abstract
The Drosophila giant fiber (GF) escape circuit is an extensively studied model for neuron connectivity and function. Researchers have long taken advantage of the simple linear neuronal pathway, which begins at peripheral sensory modalities, travels through the central GF interneuron (GFI) to motor neurons, and terminates on wing/leg muscles. This circuit is more complex than it seems, however, as there exists a complex web of coupled neurons connected to the GFI that widely innervates the thoracic ganglion. Here, we define four new neuron clusters dye coupled to the central GFI, which we name GF coupled (GFC) 1-4. We identify new transgenic Gal4 drivers that express specifically in these neurons, and map both neuronal architecture and synaptic polarity. GFC1-4 share a central site of GFI connectivity, the inframedial bridge, where the neurons each form electrical synapses. Targeted apoptotic ablation of GFC1 reveals a key role for the proper development of the GF circuit, including the maintenance of GFI connectivity with upstream and downstream synaptic partners. GFC1 ablation frequently results in the loss of one GFI, which is always compensated for by contralateral innervation from a branch of the persisting GFI axon. Overall, this work reveals extensively coupled interconnectivity within the GF circuit, and the requirement of coupled neurons for circuit development. Identification of this large population of electrically coupled neurons in this classic model, and the ability to genetically manipulate these electrically synapsed neurons, expands the GF system capabilities for the nuanced, sophisticated circuit dissection necessary for deeper investigations into brain formation.
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Affiliation(s)
- Tyler Kennedy
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
- Department of Cell and Developmental Biology, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
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39
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Shmueli A, Shalit T, Okun E, Shohat-Ophir G. The Toll Pathway in the Central Nervous System of Flies and Mammals. Neuromolecular Med 2018; 20:419-436. [PMID: 30276585 DOI: 10.1007/s12017-018-8515-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 09/26/2018] [Indexed: 12/20/2022]
Abstract
Toll receptors, first identified to regulate embryogenesis and immune responses in the adult fly and subsequently defined as the principal sensors of infection in mammals, are increasingly appreciated for their impact on the homeostasis of the central as well as the peripheral nervous systems. Whereas in the context of immunity, the fly Toll and the mammalian TLR pathways have been researched in parallel, the expression pattern and functionality have largely been researched disparately. Herein, we provide data on the expression pattern of the Toll homologues, signaling components, and downstream effectors in ten different cell populations of the adult fly central nervous system (CNS). We have compared the expression of the different Toll pathways in the fly to the expression of TLRs in the mouse brain and discussed the implications with respect to commonalities, differences, and future perspectives.
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Affiliation(s)
- Anat Shmueli
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Tali Shalit
- The Mantoux Bioinformatics institute of the Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Eitan Okun
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel.
- The Paul Feder Laboratory on Alzheimer's Disease Research, Ramat-Gan, Israel.
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Building 901, room 315, Ramat-Gan, 5290000, Israel.
| | - Galit Shohat-Ophir
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel.
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40
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Abstract
Like humans, insects face the threat of viral infection. Despite having repercussions on human health and disease, knowledge gaps exist for how insects cope with viral pathogens. Drosophila melanogaster serves as an ideal insect model due to its genetic tractability. When encountering a pathogen, two major approaches to fight disease are resistance strategies and tolerance strategies. Disease resistance strategies promote the health of the infected host by reducing pathogen load. Multiple disease resistance mechanisms have been identified in Drosophila: RNA interference, Jak/STAT signaling, Toll signaling, IMD signaling, and autophagy. Disease tolerance mechanisms, in contrast, do not reduce pathogen load directly, but rather mitigate the stress and damage incurred by infection. The main benefit of tolerance mechanisms may therefore be to provide the host with time to engage antiviral resistance mechanisms that eliminate the threat. In this review, antiviral resistance mechanisms used by Drosophila will be described and compared to mammalian antiviral mechanisms. Disease tolerance will then be explained in a broader context as this is a burgeoning field of study.
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Affiliation(s)
- Jonathan Chow
- Division of Gastroenterology, Harvard Medical School, Boston Children's Hospital, Boston, MA, United States
| | - Jonathan C Kagan
- Division of Gastroenterology, Harvard Medical School, Boston Children's Hospital, Boston, MA, United States.
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41
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Combinations of DIPs and Dprs control organization of olfactory receptor neuron terminals in Drosophila. PLoS Genet 2018; 14:e1007560. [PMID: 30102700 PMCID: PMC6107282 DOI: 10.1371/journal.pgen.1007560] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 08/23/2018] [Accepted: 07/13/2018] [Indexed: 12/22/2022] Open
Abstract
In Drosophila, 50 classes of olfactory receptor neurons (ORNs) connect to 50 class-specific and uniquely positioned glomeruli in the antennal lobe. Despite the identification of cell surface receptors regulating axon guidance, how ORN axons sort to form 50 stereotypical glomeruli remains unclear. Here we show that the heterophilic cell adhesion proteins, DIPs and Dprs, are expressed in ORNs during glomerular formation. Many ORN classes express a unique combination of DIPs/dprs, with neurons of the same class expressing interacting partners, suggesting a role in class-specific self-adhesion between ORN axons. Analysis of DIP/Dpr expression revealed that ORNs that target neighboring glomeruli have different combinations, and ORNs with very similar DIP/Dpr combinations can project to distant glomeruli in the antennal lobe. DIP/Dpr profiles are dynamic during development and correlate with sensilla type lineage for some ORN classes. Perturbations of DIP/dpr gene function result in local projection defects of ORN axons and glomerular positioning, without altering correct matching of ORNs with their target neurons. Our results suggest that context-dependent differential adhesion through DIP/Dpr combinations regulate self-adhesion and sort ORN axons into uniquely positioned glomeruli. In the human brain there are over 80 billion neurons that form approximately 100 trillion specific connections. How the brain organizes the axon terminals of these neurons into distinct synaptic units on such a large scale is largely unknown. In Drosophila, 50 classes of olfactory receptor neurons (ORNs) connect to 50 class-specific and uniquely positioned glomeruli in the antennal lobe, providing a complex yet workable model to understand the organization of glomerular structures and morphology. Here we show that the heterophilic cell adhesion proteins, DIPs and Dprs, are expressed in ORNs during glomerular formation. Many ORN classes express a unique combination of DIPs/dprs, with neurons of the same class expressing interacting partners, suggesting a role in class-specific self-adhesion between ORN axons. Analysis of DIP/Dpr expression revealed that ORNs that target neighboring glomeruli have different combinations, and ORNs with very similar DIP/Dpr combinations can project to distant glomeruli in the antennal lobe. Perturbations of DIP/dpr gene function result in local projection defects of ORN axons and glomerular positioning, without altering correct matching of ORNs with their target neurons. Our results suggest that context-dependent differential adhesion through DIP/Dpr combinations regulate self-adhesion and sort ORN axons into uniquely positioned glomeruli.
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42
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Tlr7 deletion alters expression profiles of genes related to neural function and regulates mouse behaviors and contextual memory. Brain Behav Immun 2018; 72:101-113. [PMID: 29885943 DOI: 10.1016/j.bbi.2018.06.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 05/24/2018] [Accepted: 06/06/2018] [Indexed: 11/22/2022] Open
Abstract
The neuronal innate immune system recognizes endogenous danger signals and regulates neuronal development and function. Toll-like receptor 7 (TLR7), one of the TLRs that trigger innate immune responses in neurons, controls neuronal morphology. To further assess the function of TLR7 in the brain, we applied next generation sequencing to investigate the effect of Tlr7 deletion on gene expression in hippocampal and cortical mixed cultures and on mouse behaviors. Since previous in vivo study suggested that TLR7 is more critical for neuronal morphology at earlier developmental stages, we analyzed two time-points (4 and 18 DIV) to represent young and mature neurons, respectively. At 4 DIV, Tlr7 KO neurons exhibited reduced expression of genes involved in neuronal development, synaptic organization and activity and behaviors. Some of these Tlr7-regulated genes are also associated with multiple neurological and neuropsychiatric diseases. TLR7-regulated transcriptomic profiles differed at 18 DIV. Apart from neuronal genes, genes related to glial cell development and differentiation became sensitive to Tlr7 deletion at 18 DIV. Moreover, Tlr7 KO mice exhibited altered behaviors in terms of anxiety, aggression, olfaction and contextual fear memory. Electrophysiological analysis further showed an impairment of long-term potentiation in Tlr7 KO hippocampus. Taken together, these results indicate that TLR7 regulates neural development and brain function, even in the absence of infectious or pathogenic molecules. Our findings strengthen evidence for the role of the neuronal innate immune system in fine-tuning neuronal morphology and activity and implicate it in neuropsychiatric disorders.
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43
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Millard SS, Pecot MY. Strategies for assembling columns and layers in the Drosophila visual system. Neural Dev 2018; 13:11. [PMID: 29875010 PMCID: PMC5991427 DOI: 10.1186/s13064-018-0106-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 04/24/2018] [Indexed: 11/23/2022] Open
Abstract
A striking feature of neural circuit structure is the arrangement of neurons into regularly spaced ensembles (i.e. columns) and neural connections into parallel layers. These patterns of organization are thought to underlie precise synaptic connectivity and provide a basis for the parallel processing of information. In this article we discuss in detail specific findings that contribute to a framework for understanding how columns and layers are assembled in the Drosophila visual system, and discuss their broader implications.
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Affiliation(s)
- S. Sean Millard
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Matthew Y. Pecot
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115 USA
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44
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Hung YF, Chen CY, Shih YC, Liu HY, Huang CM, Hsueh YP. Endosomal TLR3, TLR7, and TLR8 control neuronal morphology through different transcriptional programs. J Cell Biol 2018; 217:2727-2742. [PMID: 29777026 PMCID: PMC6080926 DOI: 10.1083/jcb.201712113] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 04/09/2018] [Accepted: 05/03/2018] [Indexed: 02/07/2023] Open
Abstract
Neuroinflammation is associated with diverse neurological disorders. Endosomal Toll-like receptors (TLRs) including TLR3, TLR7, and TLR8 cell-autonomously regulate neuronal differentiation. However, the mechanisms by which these three TLRs affect neuronal morphology are unclear. In this study, we compare these TLRs in mouse neurons. By combining in vitro neuronal cultures, in utero electroporation, and transcriptomic profiling, we show that TLR8, TLR7, and TLR3 promote dendritic pruning via MYD88 signaling. However, they induce different transcriptomic profiles related to innate immunity, signaling, and neuronal development. The temporal expression patterns and the effects on neuronal morphology are not identical upon activation of these endosomal TLRs. Pathway analyses and in vitro studies specifically implicate mitogen-activated protein kinase signaling in TLR8-mediated dendritic pruning. We further show that TLR8 is more critical for dendritic arborization at a late development stage in vivo. The activation of TLR8, TLR7, or TLR3 results in dendritic shortening, and TLR7 and TLR3 but not TLR8 also control axonal growth. In-depth transcriptomic analyses show that TLRs use different downstream pathways to control neuronal morphology, which may contribute to neuronal development and pathological responses.
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Affiliation(s)
- Yun-Fen Hung
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Chiung-Ya Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Yi-Chun Shih
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Hsin-Yu Liu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | | | - Yi-Ping Hsueh
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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45
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Anthoney N, Foldi I, Hidalgo A. Toll and Toll-like receptor signalling in development. Development 2018; 145:145/9/dev156018. [DOI: 10.1242/dev.156018] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
ABSTRACT
The membrane receptor Toll and the related Toll-like receptors (TLRs) are best known for their universal function in innate immunity. However, Toll/TLRs were initially discovered in a developmental context, and recent studies have revealed that Toll/TLRs carry out previously unanticipated functions in development, regulating cell fate, cell number, neural circuit connectivity and synaptogenesis. Furthermore, knowledge of their molecular mechanisms of action is expanding and has highlighted that Toll/TLRs function beyond the canonical NF-κB pathway to regulate cell-to-cell communication and signalling at the synapse. Here, we provide an overview of Toll/TLR signalling and discuss how this signalling pathway regulates various aspects of development across species.
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Affiliation(s)
- Niki Anthoney
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Istvan Foldi
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Alicia Hidalgo
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
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46
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Li H, Shuster SA, Li J, Luo L. Linking neuronal lineage and wiring specificity. Neural Dev 2018; 13:5. [PMID: 29653548 PMCID: PMC5899351 DOI: 10.1186/s13064-018-0102-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/14/2018] [Indexed: 02/01/2023] Open
Abstract
Brain function requires precise neural circuit assembly during development. Establishing a functional circuit involves multiple coordinated steps ranging from neural cell fate specification to proper matching between pre- and post-synaptic partners. How neuronal lineage and birth timing influence wiring specificity remains an open question. Recent findings suggest that the relationships between lineage, birth timing, and wiring specificity vary in different neuronal circuits. In this review, we summarize our current understanding of the cellular, molecular, and developmental mechanisms linking neuronal lineage and birth timing to wiring specificity in a few specific systems in Drosophila and mice, and review different methods employed to explore these mechanisms.
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Affiliation(s)
- Hongjie Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - S. Andrew Shuster
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
- Neurosciences Graduate Program, Stanford University, Stanford, CA 94305 USA
| | - Jiefu Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
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47
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Dang P, Fisher SA, Stefanik DJ, Kim J, Raper JA. Coordination of olfactory receptor choice with guidance receptor expression and function in olfactory sensory neurons. PLoS Genet 2018; 14:e1007164. [PMID: 29385124 PMCID: PMC5809090 DOI: 10.1371/journal.pgen.1007164] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 02/12/2018] [Accepted: 12/25/2017] [Indexed: 11/18/2022] Open
Abstract
Olfactory sensory neurons choose to express a single odorant receptor (OR) from a large gene repertoire and extend axons to reproducible, OR-specific locations within the olfactory bulb. This developmental process produces a topographically organized map of odorant experience in the brain. The axon guidance mechanisms that generate this pattern of connectivity, as well as those that coordinate OR choice and axonal guidance receptor expression, are incompletely understood. We applied the powerful approach of single-cell RNA-seq on newly born olfactory sensory neurons (OSNs) in young zebrafish larvae to address these issues. Expression profiles were generated for 56 individual Olfactory Marker Protein (OMP) positive sensory neurons by single-cell (SC) RNA-seq. We show that just as in mouse OSNs, mature zebrafish OSNs typically express a single predominant OR transcript. Our previous work suggests that OSN targeting is related to the OR clade from which a sensory neuron chooses to express its odorant receptor. We categorized each of the mature cells based on the clade of their predominantly expressed OR. Transcripts expressed at higher levels in each of three clade-related categories were identified using Penalized Linear Discriminant Analysis (PLDA). A genome-wide approach was used to identify membrane-associated proteins that are most likely to have guidance-related activity. We found that OSNs that choose to express an OR from a particular clade also express specific subsets of potential axon guidance genes and transcription factors. We validated our identification of candidate axon guidance genes for one clade of OSNs using bulk RNA-seq from a subset of transgene-labeled neurons that project to a single protoglomerulus. The differential expression patterns of selected candidate guidance genes were confirmed using fluorescent in situ hybridization. Most importantly, we observed axonal mistargeting in knockouts of three candidate axonal guidance genes identified in this analysis: nrp1a, nrp1b, and robo2. In each case, targeting errors were detected in the subset of axons that normally express these transcripts at high levels, and not in the axons that express them at low levels. Our findings demonstrate that specific, functional, axonal guidance related genes are expressed in subsets of OSNs that that can be categorized by their patterns of OR expression.
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Affiliation(s)
- Puneet Dang
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania Philadelphia, PA, United States of America
| | - Stephen A. Fisher
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Derek J. Stefanik
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Junhyong Kim
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Jonathan A. Raper
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania Philadelphia, PA, United States of America
- * E-mail:
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48
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Li H, Horns F, Wu B, Xie Q, Li J, Li T, Luginbuhl DJ, Quake SR, Luo L. Classifying Drosophila Olfactory Projection Neuron Subtypes by Single-Cell RNA Sequencing. Cell 2017; 171:1206-1220.e22. [PMID: 29149607 DOI: 10.1016/j.cell.2017.10.019] [Citation(s) in RCA: 160] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 08/05/2017] [Accepted: 10/12/2017] [Indexed: 11/19/2022]
Abstract
The definition of neuronal type and how it relates to the transcriptome are open questions. Drosophila olfactory projection neurons (PNs) are among the best-characterized neuronal types: different PN classes target dendrites to distinct olfactory glomeruli, while PNs of the same class exhibit indistinguishable anatomical and physiological properties. Using single-cell RNA sequencing, we comprehensively characterized the transcriptomes of most PN classes and unequivocally mapped transcriptomes to specific olfactory function for six classes. Transcriptomes of closely related PN classes exhibit the largest differences during circuit assembly but become indistinguishable in adults, suggesting that neuronal subtype diversity peaks during development. Transcription factors and cell-surface molecules are the most differentially expressed genes between classes and are highly informative in encoding cell identity, enabling us to identify a new lineage-specific transcription factor that instructs PN dendrite targeting. These findings establish that neuronal transcriptomic identity corresponds with anatomical and physiological identity defined by connectivity and function.
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Affiliation(s)
- Hongjie Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Felix Horns
- Biophysics Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Bing Wu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Qijing Xie
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Jiefu Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Tongchao Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - David J Luginbuhl
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Stephen R Quake
- Departments of Bioengineering and Applied Physics, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, Stanford, CA 94305, USA.
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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49
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Anzo M, Sekine S, Makihara S, Chao K, Miura M, Chihara T. Dendritic Eph organizes dendrodendritic segregation in discrete olfactory map formation in Drosophila. Genes Dev 2017. [PMID: 28637694 PMCID: PMC5495121 DOI: 10.1101/gad.297424.117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Proper function of the neural network results from the precise connections between axons and dendrites of presynaptic and postsynaptic neurons, respectively. In the Drosophila olfactory system, the dendrites of projection neurons (PNs) stereotypically target one of ∼50 glomeruli in the antennal lobe (AL), the primary olfactory center in the brain, and form synapses with the axons of olfactory receptor neurons (ORNs). Here, we show that Eph and Ephrin, the well-known axon guidance molecules, instruct the dendrodendritic segregation during the discrete olfactory map formation. The Eph receptor tyrosine kinase is highly expressed and localized in the glomeruli related to reproductive behavior in the developing AL. In one of the pheromone-sensing glomeruli (DA1), the Eph cell-autonomously regulates its dendrites to reside in a single glomerulus by interacting with Ephrins expressed in adjacent PN dendrites. Our data demonstrate that the trans interaction between dendritic Eph and Ephrin is essential for the PN dendritic boundary formation in the DA1 olfactory circuit, potentially enabling strict segregation of odor detection between pheromones and the other odors.
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Affiliation(s)
- Marie Anzo
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Sayaka Sekine
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shirin Makihara
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kinhong Chao
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masayuki Miura
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Japan Agency for Medical Research and Development (AMED)-CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo 100-0004, Japan
| | - Takahiro Chihara
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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Ulian-Benitez S, Bishop S, Foldi I, Wentzell J, Okenwa C, Forero MG, Zhu B, Moreira M, Phizacklea M, McIlroy G, Li G, Gay NJ, Hidalgo A. Kek-6: A truncated-Trk-like receptor for Drosophila neurotrophin 2 regulates structural synaptic plasticity. PLoS Genet 2017; 13:e1006968. [PMID: 28846707 PMCID: PMC5591008 DOI: 10.1371/journal.pgen.1006968] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 09/08/2017] [Accepted: 08/08/2017] [Indexed: 01/19/2023] Open
Abstract
Neurotrophism, structural plasticity, learning and long-term memory in mammals critically depend on neurotrophins binding Trk receptors to activate tyrosine kinase (TyrK) signaling, but Drosophila lacks full-length Trks, raising the question of how these processes occur in the fly. Paradoxically, truncated Trk isoforms lacking the TyrK predominate in the adult human brain, but whether they have neuronal functions independently of full-length Trks is unknown. Drosophila has TyrK-less Trk-family receptors, encoded by the kekkon (kek) genes, suggesting that evolutionarily conserved functions for this receptor class may exist. Here, we asked whether Keks function together with Drosophila neurotrophins (DNTs) at the larval glutamatergic neuromuscular junction (NMJ). We tested the eleven LRR and Ig-containing (LIG) proteins encoded in the Drosophila genome for expression in the central nervous system (CNS) and potential interaction with DNTs. Kek-6 is expressed in the CNS, interacts genetically with DNTs and can bind DNT2 in signaling assays and co-immunoprecipitations. Ligand binding is promiscuous, as Kek-6 can also bind DNT1, and Kek-2 and Kek-5 can also bind DNT2. In vivo, Kek-6 is found presynaptically in motoneurons, and DNT2 is produced by the muscle to function as a retrograde factor at the NMJ. Kek-6 and DNT2 regulate NMJ growth and synaptic structure. Evidence indicates that Kek-6 does not antagonise the alternative DNT2 receptor Toll-6. Instead, Kek-6 and Toll-6 interact physically, and together regulate structural synaptic plasticity and homeostasis. Using pull-down assays, we identified and validated CaMKII and VAP33A as intracellular partners of Kek-6, and show that they regulate NMJ growth and active zone formation downstream of DNT2 and Kek-6. The synaptic functions of Kek-6 could be evolutionarily conserved. This raises the intriguing possibility that a novel mechanism of structural synaptic plasticity involving truncated Trk-family receptors independently of TyrK signaling may also operate in the human brain. A long-standing paradox had been to explain how brain structural plasticity, learning and long-term memory might occur in Drosophila in the absence of canonical Trk receptors for neurotrophin (NT) ligands. NTs link structure and function in the brain enabling adjustments in cell number, dendritic, axonal and synaptic patterns, in response to neuronal activity. These events are essential for brain development, learning and long-term memory, and are thought to depend on the tyrosine-kinase function of the NT Trk receptors. However, paradoxically, the most abundant Trk isoforms in the adult human brain lack the tyrosine kinase, and their neuronal function is unknown. Remarkably, Drosophila has kinase-less receptors of the Trk family encoded by the kekkon (kek) genes, suggesting that deep evolutionary functional conservation for this receptor class could be unveiled. Here, we show that Kek-6 is a receptor for Drosophila neurotrophin 2 (DNT2) that regulates structural synaptic plasticity via CaMKII and VAP33A. The latter are well-known factors regulating synaptic structure and plasticity and vesicle release. Furthemore, Kek-6 cooperates with the alternative DNT2 receptor Toll-6, and their concerted functions are required to regulate structural homeostasis at the NMJ. Our findings suggest that in mammals truncated Trk-family receptors could also have synaptic functions in neurons independently of Tyrosine kinase signaling. This might reveal a novel mechanism of brain plasticity, with important implications for understanding also the human brain, in health and disease.
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Affiliation(s)
- Suzana Ulian-Benitez
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Simon Bishop
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Istvan Foldi
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Jill Wentzell
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Chinenye Okenwa
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | | | - Bangfu Zhu
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Marta Moreira
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Mark Phizacklea
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Graham McIlroy
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Guiyi Li
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Nicholas J. Gay
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Alicia Hidalgo
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- * E-mail:
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