1
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Lymer S, Patel K, Lennon J, Blau J. Circadian clock neurons use activity-regulated gene expression for structural plasticity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.25.595887. [PMID: 38826237 PMCID: PMC11142243 DOI: 10.1101/2024.05.25.595887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Drosophila s-LNv circadian pacemaker neurons show dramatic structural plasticity, with their projections expanded at dawn and then retracted by dusk. This predictable plasticity makes s-LNvs ideal to study molecular mechanisms of plasticity. Although s-LNv plasticity is controlled by their molecular clock, changing s-LNv excitability also regulates plasticity. Here, we tested the idea that s-LNvs use activity-regulated genes to control plasticity. We found that inducing expression of either of the activity-regulated transcription factors Hr38 or Sr (orthologs of mammalian Nr4a1 and Egr1) is sufficient to rapidly expand s-LNv projections. Conversely, transiently knocking down expression of either Hr38 or sr blocks expansion of s-LNv projections at dawn. We show that Hr38 rapidly induces transcription of sif, which encodes a Rac1 GEF required for s-LNv plasticity rhythms. We conclude that the s-LNv molecular clock controls s-LNv excitability, which couples to an activity-regulated gene expression program to control s-LNv plasticity.
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2
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Brown MP, Verma S, Palmer I, Guerrero Zuniga A, Mehta A, Rosensweig C, Keles MF, Wu MN. A subclass of evening cells promotes the switch from arousal to sleep at dusk. Curr Biol 2024; 34:2186-2199.e3. [PMID: 38723636 PMCID: PMC11111347 DOI: 10.1016/j.cub.2024.04.039] [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: 08/25/2023] [Revised: 03/20/2024] [Accepted: 04/17/2024] [Indexed: 05/21/2024]
Abstract
Animals exhibit rhythmic patterns of behavior that are shaped by an internal circadian clock and the external environment. Although light intensity varies across the day, there are particularly robust differences at twilight (dawn/dusk). These periods are also associated with major changes in behavioral states, such as the transition from arousal to sleep. However, the neural mechanisms by which time and environmental conditions promote these behavioral transitions are poorly defined. Here, we show that the E1 subclass of Drosophila evening clock neurons promotes the transition from arousal to sleep at dusk. We first demonstrate that the cell-autonomous clocks of E2 neurons primarily drive and adjust the phase of evening anticipation, the canonical behavior associated with "evening" clock neurons. We next show that conditionally silencing E1 neurons causes a significant delay in sleep onset after dusk. However, rather than simply promoting sleep, activating E1 neurons produces time- and light-dependent effects on behavior. Activation of E1 neurons has no effect early in the day but then triggers arousal before dusk and induces sleep after dusk. Strikingly, these activation-induced phenotypes depend on the presence of light during the day. Despite their influence on behavior around dusk, in vivo voltage imaging of E1 neurons reveals that their spiking rate and pattern do not significantly change throughout the day. Moreover, E1-specific clock ablation has no effect on arousal or sleep. Thus, we suggest that, rather than specifying "evening" time, E1 neurons act, in concert with other rhythmic neurons, to promote behavioral transitions at dusk.
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Affiliation(s)
- Matthew P Brown
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Shubha Verma
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Isabelle Palmer
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | | | - Anuradha Mehta
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Clark Rosensweig
- Department of Neurobiology, Northwestern University, Evanston, IL 60201, USA
| | - Mehmet F Keles
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Mark N Wu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA.
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3
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Mao R, Yu J, Deng B, Dai X, Du Y, Du S, Zhang W, Rao Y. Conditional chemoconnectomics (cCCTomics) as a strategy for efficient and conditional targeting of chemical transmission. eLife 2024; 12:RP91927. [PMID: 38686992 PMCID: PMC11060718 DOI: 10.7554/elife.91927] [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] [Indexed: 05/02/2024] Open
Abstract
Dissection of neural circuitry underlying behaviors is a central theme in neurobiology. We have previously proposed the concept of chemoconnectome (CCT) to cover the entire chemical transmission between neurons and target cells in an organism and created tools for studying it (CCTomics) by targeting all genes related to the CCT in Drosophila. Here we have created lines targeting the CCT in a conditional manner after modifying GFP RNA interference, Flp-out, and CRISPR/Cas9 technologies. All three strategies have been validated to be highly effective, with the best using chromatin-peptide fused Cas9 variants and scaffold optimized sgRNAs. As a proof of principle, we conducted a comprehensive intersection analysis of CCT genes expression profiles in the clock neurons, uncovering 43 CCT genes present in clock neurons. Specific elimination of each from clock neurons revealed that loss of the neuropeptide CNMa in two posterior dorsal clock neurons (DN1ps) or its receptor (CNMaR) caused advanced morning activity, indicating a suppressive role of CNMa-CNMaR on morning anticipation, opposite to the promoting role of PDF-PDFR on morning anticipation. These results demonstrate the effectiveness of conditional CCTomics and its tools created here and establish an antagonistic relationship between CNMa-CNMaR and PDF-PDFR signaling in regulating morning anticipation.
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Affiliation(s)
- Renbo Mao
- Laboratory of Neurochemical Biology, Chinese Institute for Brain ResearchBeijingChina
- PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Department of Chemical Biology, College of Chemistry and Chemical Engineering, School of Pharmaceutical Sciences, Peking UniversityBeijingChina
- Chinese Institutes for Medical Research, Capital Medical University; Changping LaboratoryChangpingChina
- Research Unit of Medical Neurobiology, Chinese Academy of Medical SciencesBeijingChina
- National Institute of Biological Sciences, Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Jianjun Yu
- Laboratory of Neurochemical Biology, Chinese Institute for Brain ResearchBeijingChina
- PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Department of Chemical Biology, College of Chemistry and Chemical Engineering, School of Pharmaceutical Sciences, Peking UniversityBeijingChina
- Chinese Institutes for Medical Research, Capital Medical University; Changping LaboratoryChangpingChina
- Research Unit of Medical Neurobiology, Chinese Academy of Medical SciencesBeijingChina
| | - Bowen Deng
- Laboratory of Neurochemical Biology, Chinese Institute for Brain ResearchBeijingChina
- PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Department of Chemical Biology, College of Chemistry and Chemical Engineering, School of Pharmaceutical Sciences, Peking UniversityBeijingChina
- Chinese Institutes for Medical Research, Capital Medical University; Changping LaboratoryChangpingChina
- Research Unit of Medical Neurobiology, Chinese Academy of Medical SciencesBeijingChina
| | - Xihuimin Dai
- Laboratory of Neurochemical Biology, Chinese Institute for Brain ResearchBeijingChina
- PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Department of Chemical Biology, College of Chemistry and Chemical Engineering, School of Pharmaceutical Sciences, Peking UniversityBeijingChina
- Chinese Institutes for Medical Research, Capital Medical University; Changping LaboratoryChangpingChina
- Research Unit of Medical Neurobiology, Chinese Academy of Medical SciencesBeijingChina
| | - Yuyao Du
- Laboratory of Neurochemical Biology, Chinese Institute for Brain ResearchBeijingChina
- PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Department of Chemical Biology, College of Chemistry and Chemical Engineering, School of Pharmaceutical Sciences, Peking UniversityBeijingChina
- Chinese Institutes for Medical Research, Capital Medical University; Changping LaboratoryChangpingChina
- Research Unit of Medical Neurobiology, Chinese Academy of Medical SciencesBeijingChina
| | - Sujie Du
- Laboratory of Neurochemical Biology, Chinese Institute for Brain ResearchBeijingChina
- PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Department of Chemical Biology, College of Chemistry and Chemical Engineering, School of Pharmaceutical Sciences, Peking UniversityBeijingChina
- Chinese Institutes for Medical Research, Capital Medical University; Changping LaboratoryChangpingChina
- Research Unit of Medical Neurobiology, Chinese Academy of Medical SciencesBeijingChina
| | - Wenxia Zhang
- Laboratory of Neurochemical Biology, Chinese Institute for Brain ResearchBeijingChina
- PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Department of Chemical Biology, College of Chemistry and Chemical Engineering, School of Pharmaceutical Sciences, Peking UniversityBeijingChina
- Chinese Institutes for Medical Research, Capital Medical University; Changping LaboratoryChangpingChina
- Research Unit of Medical Neurobiology, Chinese Academy of Medical SciencesBeijingChina
| | - Yi Rao
- Laboratory of Neurochemical Biology, Chinese Institute for Brain ResearchBeijingChina
- PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Department of Chemical Biology, College of Chemistry and Chemical Engineering, School of Pharmaceutical Sciences, Peking UniversityBeijingChina
- Chinese Institutes for Medical Research, Capital Medical University; Changping LaboratoryChangpingChina
- Research Unit of Medical Neurobiology, Chinese Academy of Medical SciencesBeijingChina
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Sekiguchi M, Katoh S, Yokosako T, Saito A, Sakai M, Fukuda A, Itoh TQ, Yoshii T. The Trissin/TrissinR signaling pathway in the circadian network regulates evening activity in Drosophila melanogaster under constant dark conditions. Biochem Biophys Res Commun 2024; 704:149705. [PMID: 38430699 DOI: 10.1016/j.bbrc.2024.149705] [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: 01/19/2024] [Accepted: 02/20/2024] [Indexed: 03/05/2024]
Abstract
The circadian clock in Drosophila is governed by a neural network comprising approximately 150 neurons, known as clock neurons, which are intricately interconnected by various neurotransmitters. The neuropeptides that play functional roles in these clock neurons have been identified; however, the roles of some neuropeptides, such as Trissin, remain unclear. Trissin is expressed in lateral dorsal clock neurons (LNds), while its receptor, TrissinR, is expressed in dorsal neuron 1 (DN1) and LNds. In this study, we investigated the role of the Trissin/TrissinR signaling pathway within the circadian network in Drosophila melanogaster. Analysis involving our newly generated antibody against the Trissin precursor revealed that Trissin expression in the LNds cycles in a circadian manner. Behavioral analysis further demonstrated that flies with Trissin or TrissinR knockout or knockdown showed delayed evening activity offset under constant darkness conditions. Notably, this observed delay in evening activity offset in TrissinRNAi flies was restored via the additional knockdown of Ion transport peptide (ITP), indicating that the Trissin/TrissinR signaling pathway transmits information via ITP. Therefore, this pathway may be a key regulator of the timing of evening activity offset termination, orchestrating its effects in collaboration with the neuropeptide, ITP.
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Affiliation(s)
- Manabu Sekiguchi
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
| | - Shun Katoh
- Department of Biology, Faculty of Science, Okayama University, Okayama, 700-8530, Japan
| | - Tatsuya Yokosako
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Aika Saito
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Momoka Sakai
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Ayumi Fukuda
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Taichi Q Itoh
- Faculty of Arts and Science, Kyushu University, Fukuoka, 819-0395, Japan
| | - Taishi Yoshii
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan; Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
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Cavieres-Lepe J, Amini E, Zabel M, Nässel DR, Stanewsky R, Wegener C, Ewer J. Timed receptor tyrosine kinase signaling couples the central and a peripheral circadian clock in Drosophila. Proc Natl Acad Sci U S A 2024; 121:e2308067121. [PMID: 38442160 PMCID: PMC10945756 DOI: 10.1073/pnas.2308067121] [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: 05/16/2023] [Accepted: 02/01/2024] [Indexed: 03/07/2024] Open
Abstract
Circadian clocks impose daily periodicities to behavior, physiology, and metabolism. This control is mediated by a central clock and by peripheral clocks, which are synchronized to provide the organism with a unified time through mechanisms that are not fully understood. Here, we characterized in Drosophila the cellular and molecular mechanisms involved in coupling the central clock and the peripheral clock located in the prothoracic gland (PG), which together control the circadian rhythm of emergence of adult flies. The time signal from central clock neurons is transmitted via small neuropeptide F (sNPF) to neurons that produce the neuropeptide Prothoracicotropic Hormone (PTTH), which is then translated into daily oscillations of Ca2+ concentration and PTTH levels. PTTH signaling is required at the end of metamorphosis and transmits time information to the PG through changes in the expression of the PTTH receptor tyrosine kinase (RTK), TORSO, and of ERK phosphorylation, a key component of PTTH transduction. In addition to PTTH, we demonstrate that signaling mediated by other RTKs contributes to the rhythmicity of emergence. Interestingly, the ligand to one of these receptors (Pvf2) plays an autocrine role in the PG, which may explain why both central brain and PG clocks are required for the circadian gating of emergence. Our findings show that the coupling between the central and the PG clock is unexpectedly complex and involves several RTKs that act in concert and could serve as a paradigm to understand how circadian clocks are coordinated.
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Affiliation(s)
- Javier Cavieres-Lepe
- Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso2360102, Chile
| | - Emad Amini
- Julius-Maximilians-Universität Würzburg, Biocenter, Theodor-Boveri-Institute, Neurobiology and Genetics, Am Hubland, Würzburg97074, Germany
| | - Maia Zabel
- Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso2360102, Chile
| | - Dick R. Nässel
- Department of Zoology, Stockholm University, 10691Stockholm, Sweden
| | - Ralf Stanewsky
- Institute of Neuro- and Behavioral Biology, Multiscale Imaging Centre, University of Münster, 48149Münster, Germany
| | - Christian Wegener
- Julius-Maximilians-Universität Würzburg, Biocenter, Theodor-Boveri-Institute, Neurobiology and Genetics, Am Hubland, Würzburg97074, Germany
| | - John Ewer
- Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso2360102, Chile
- Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso2360102, Chile
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Nakano H, Sakai T. Impact of Drosophila LIM homeodomain protein Apterous on the morphology of the adult mushroom body. Biochem Biophys Res Commun 2023; 682:77-84. [PMID: 37804590 DOI: 10.1016/j.bbrc.2023.09.071] [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: 09/11/2023] [Accepted: 09/23/2023] [Indexed: 10/09/2023]
Abstract
A LIM homeodomain transcription factor Apterous (Ap) regulates embryonic and larval neurodevelopment in Drosophila. Although Ap is still expressed in the adult brain, it remains elusive whether Ap is involved in neurodevelopmental events in the adult brain because flies homozygous for ap mutations are usually lethal before they reach the adult stage. In this study, using adult escapers of ap knockout (KO) homozygotes, we examined whether the complete lack of ap expression affects the morphology of the mushroom body (MB) neurons and Pigment-dispersing factor (Pdf)-positive clock neurons in the adult brain. Although ap KO escapers showed severe structural defects of MB neurons, no clear morphological defects were found in Pdf-positive clock neurons. These results suggest that Ap in the adult brain is essential for the neurodevelopment of specific ap-positive neurons, but it is not necessarily involved in the development of all ap-positive neurons.
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Affiliation(s)
- Hikari Nakano
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, 192-0397, Japan
| | - Takaomi Sakai
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, 192-0397, Japan.
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7
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Gundermann DG, Lymer S, Blau J. A rapid and dynamic role for FMRP in the plasticity of adult neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.01.555985. [PMID: 37693612 PMCID: PMC10491314 DOI: 10.1101/2023.09.01.555985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Fragile X syndrome (FXS) is a neuro-developmental disorder caused by silencing Fmr1, which encodes the RNA-binding protein FMRP. Although Fmr1 is expressed in adult neurons, it has been challenging to separate acute from chronic effects of loss of Fmr1 in models of FXS. We have used the precision of Drosophila genetics to test if Fmr1 acutely affects adult neuronal plasticity in vivo, focusing on the s-LNv circadian pacemaker neurons that show 24 hour rhythms in structural plasticity. We found that over-expressing Fmr1 for only 4 hours blocks the activity-dependent expansion of s-LNv projections without altering the circadian clock or activity-regulated gene expression. Conversely, acutely reducing Fmr1 expression prevented s-LNv projections from retracting. One FMRP target that we identified in s-LNvs is sif, which encodes a Rac1 GEF. Our data indicate that FMRP normally reduces sif mRNA translation at dusk to reduce Rac1 activity. Overall, our data reveal a previously unappreciated rapid and direct role for FMRP in acutely regulating neuronal plasticity in adult neurons, and underscore the importance of RNA-binding proteins in this process.
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Affiliation(s)
- Daniel G Gundermann
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
| | - Seana Lymer
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
- Current address: Proteintech Genomics, 11588 Sorrento Valley Rd, San Diego, CA 92121
| | - Justin Blau
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
- Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, UAE
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Brown MP, Verma S, Palmer I, Zuniga AG, Rosensweig C, Keles MF, Wu MN. A subclass of evening cells promotes the switch from arousal to sleep at dusk. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555147. [PMID: 37693540 PMCID: PMC10491161 DOI: 10.1101/2023.08.28.555147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Animals exhibit rhythmic patterns of behavior that are shaped by an internal circadian clock and the external environment. While light intensity varies across the day, there are particularly robust differences at twilight (dawn/dusk). These periods are also associated with major changes in behavioral states, such as the transition from arousal to sleep. However, the neural mechanisms by which time and environmental conditions promote these behavioral transitions are poorly defined. Here, we show that the E1 subclass of Drosophila evening clock neurons promotes the transition from arousal to sleep at dusk. We first demonstrate that the cell-autonomous clocks of E2 neurons alone are required to drive and adjust the phase of evening anticipation, the canonical behavior associated with "evening" clock neurons. We next show that conditionally silencing E1 neurons causes a significant delay in sleep onset after dusk. However, rather than simply promoting sleep, activating E1 neurons produces time- and light- dependent effects on behavior. Activation of E1 neurons has no effect early in the day, but then triggers arousal before dusk and induces sleep after dusk. Strikingly, these phenotypes critically depend on the presence of light during the day. Despite their influence on behavior around dusk, in vivo voltage imaging of E1 neurons reveals that their spiking rate does not vary between dawn and dusk. Moreover, E1-specific clock ablation has no effect on arousal or sleep. Thus, we suggest that, rather than specifying "evening" time, E1 neurons act, in concert with other rhythmic neurons, to promote behavioral transitions at dusk.
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Affiliation(s)
- Matthew P. Brown
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - Shubha Verma
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - Isabelle Palmer
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | | | - Clark Rosensweig
- Department of Neurobiology, Northwestern University, Evanston, IL 60201, U.S.A
| | - Mehmet F. Keles
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - Mark N. Wu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, U.S.A
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
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Richhariya S, Shin D, Le JQ, Rosbash M. Dissecting neuron-specific functions of circadian genes using modified cell-specific CRISPR approaches. Proc Natl Acad Sci U S A 2023; 120:e2303779120. [PMID: 37428902 PMCID: PMC10629539 DOI: 10.1073/pnas.2303779120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/07/2023] [Indexed: 07/12/2023] Open
Abstract
Circadian behavioral rhythms in Drosophila melanogaster are regulated by about 75 pairs of brain neurons. They all express the core clock genes but have distinct functions and gene expression profiles. To understand the importance of these distinct molecular programs, neuron-specific gene manipulations are essential. Although RNAi based methods are standard to manipulate gene expression in a cell-specific manner, they are often ineffective, especially in assays involving smaller numbers of neurons or weaker Gal4 drivers. We and others recently exploited a neuron-specific CRISPR-based method to mutagenize genes within circadian neurons. Here, we further explore this approach to mutagenize three well-studied clock genes: the transcription factor gene vrille, the photoreceptor gene Cryptochrome (cry), and the neuropeptide gene Pdf (pigment dispersing factor). The CRISPR-based strategy not only reproduced their known phenotypes but also assigned cry function for different light-mediated phenotypes to discrete, different subsets of clock neurons. We further tested two recently published methods for temporal regulation in adult neurons, inducible Cas9 and the auxin-inducible gene expression system. The results were not identical, but both approaches successfully showed that the adult-specific knockout of the neuropeptide Pdf reproduces the canonical loss-of-function mutant phenotypes. In summary, a CRISPR-based strategy is a highly effective, reliable, and general method to temporally manipulate gene function in specific adult neurons.
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10
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Lee H, Lim C. Circadian gating of light-induced arousal in Drosophila sleep. J Neurogenet 2022:1-11. [DOI: 10.1080/01677063.2022.2151596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Hoyeon Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Chunghun Lim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
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11
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Light triggers a network switch between circadian morning and evening oscillators controlling behaviour during daily temperature cycles. PLoS Genet 2022; 18:e1010487. [PMID: 36367867 PMCID: PMC9683589 DOI: 10.1371/journal.pgen.1010487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 11/23/2022] [Accepted: 10/20/2022] [Indexed: 11/13/2022] Open
Abstract
Proper timing of rhythmic locomotor behavior is the consequence of integrating environmental conditions and internal time dictated by the circadian clock. Rhythmic environmental input like daily light and temperature changes (called Zeitgeber) reset the molecular clock and entrain it to the environmental time zone the organism lives in. Furthermore, depending on the absolute temperature or light intensity, flies exhibit their main locomotor activity at different times of day, i.e., environmental input not only entrains the circadian clock but also determines the phase of a certain behavior. To understand how the brain clock can distinguish between (or integrate) an entraining Zeitgeber and environmental effects on activity phase, we attempted to entrain the clock with a Zeitgeber different from the environmental input used for phasing the behavior. 150 clock neurons in the Drosophila melanogaster brain control different aspects of the daily activity rhythms and are organized in various clusters. During regular 12 h light: 12 h dark cycles at constant mild temperature (LD 25°C, LD being the Zeitgeber), so called morning oscillator (MO) neurons control the increase of locomotor activity just before lights-on, while evening oscillator (EO) neurons regulate the activity increase at the end of the day, a few hours before lights-off. Here, using 12 h: 12 h 25°C:16°C temperature cycles as Zeitgeber, we attempted to look at the impact of light on phasing locomotor behavior. While in constant light and 25°C:16°C temperature cycles (LLTC), flies show an unimodal locomotor activity peak in the evening, during the same temperature cycle, but in the absence of light (DDTC), the phase of the activity peak is shifted to the morning. Here, we show that the EO is necessary for synchronized behavior in LLTC but not for entraining the molecular clock of the other clock neuronal groups, while the MO controls synchronized morning activity in DDTC. Interestingly, our data suggest that the influence of the EO on the synchronization increases depending on the length of the photoperiod (constant light vs 12 h of light). Hence, our results show that effects of different environmental cues on clock entrainment and activity phase can be separated, allowing to decipher their integration by the circadian clock. “If a clock is to provide information involved in controlling important functions, then clearly it must be reasonably reliable” said Colin Pittendrigh, one of the chronobiology pioneers in 1954. The circadian clock allows organisms to synchronize with their ecological niche. For this, the circadian clock uses rhythmic environmental parameters (Zeitgeber), the main ones being light and temperature. Hence, Colin Pittendrigh posted a still unresolved enigma in chronobiology. How can a clock be reliable when its resetting depends on environmental fluctuations that are not so reliable? Both, light and temperature vary a lot on a day-to-day basis, and animals respond to these variations depending on the time of day. Here, we propose a new model where the molecular clock resets to environmental cycles in a robust and independent manner, while the underlying neuronal oscillatory network switches its balance towards specific oscillators depending on the environmental condition thereby leading to distinct behavioral adaptation. To proof this proposed dogma in fruit flies, using temperature cycles as Zeitgeber, we demonstrate a light-induced switch of the network balance. Hence, we supply a foundation that in the future will help to understand how animals use their circadian clock to adapt their behavior to environmental changes.
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Reinhard N, Schubert FK, Bertolini E, Hagedorn N, Manoli G, Sekiguchi M, Yoshii T, Rieger D, Helfrich-Förster C. The Neuronal Circuit of the Dorsal Circadian Clock Neurons in Drosophila melanogaster. Front Physiol 2022; 13:886432. [PMID: 35574472 PMCID: PMC9100938 DOI: 10.3389/fphys.2022.886432] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 03/28/2022] [Indexed: 11/30/2022] Open
Abstract
Drosophila’s dorsal clock neurons (DNs) consist of four clusters (DN1as, DN1ps, DN2s, and DN3s) that largely differ in size. While the DN1as and the DN2s encompass only two neurons, the DN1ps consist of ∼15 neurons, and the DN3s comprise ∼40 neurons per brain hemisphere. In comparison to the well-characterized lateral clock neurons (LNs), the neuroanatomy and function of the DNs are still not clear. Over the past decade, numerous studies have addressed their role in the fly’s circadian system, leading to several sometimes divergent results. Nonetheless, these studies agreed that the DNs are important to fine-tune activity under light and temperature cycles and play essential roles in linking the output from the LNs to downstream neurons that control sleep and metabolism. Here, we used the Flybow system, specific split-GAL4 lines, trans-Tango, and the recently published fly connectome (called hemibrain) to describe the morphology of the DNs in greater detail, including their synaptic connections to other clock and non-clock neurons. We show that some DN groups are largely heterogenous. While certain DNs are strongly connected with the LNs, others are mainly output neurons that signal to circuits downstream of the clock. Among the latter are mushroom body neurons, central complex neurons, tubercle bulb neurons, neurosecretory cells in the pars intercerebralis, and other still unidentified partners. This heterogeneity of the DNs may explain some of the conflicting results previously found about their functionality. Most importantly, we identify two putative novel communication centers of the clock network: one fiber bundle in the superior lateral protocerebrum running toward the anterior optic tubercle and one fiber hub in the posterior lateral protocerebrum. Both are invaded by several DNs and LNs and might play an instrumental role in the clock network.
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Affiliation(s)
- Nils Reinhard
- Julius Maximilian University of Würzburg, Würzburg, Germany
| | | | - Enrico Bertolini
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Würzburg, Germany
| | | | - Giulia Manoli
- Julius Maximilian University of Würzburg, Würzburg, Germany
| | - Manabu Sekiguchi
- Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
| | - Taishi Yoshii
- Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
| | - Dirk Rieger
- Julius Maximilian University of Würzburg, Würzburg, Germany
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13
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Chen SC, Tang X, Goda T, Umezaki Y, Riley AC, Sekiguchi M, Yoshii T, Hamada FN. Dorsal clock networks drive temperature preference rhythms in Drosophila. Cell Rep 2022; 39:110668. [PMID: 35417715 PMCID: PMC9109596 DOI: 10.1016/j.celrep.2022.110668] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 09/21/2021] [Accepted: 03/22/2022] [Indexed: 11/24/2022] Open
Abstract
Animals display a body temperature rhythm (BTR). Little is known about the mechanisms by which a rhythmic pattern of BTR is regulated and how body temperature is set at different times of the day. As small ectotherms, Drosophila exhibit a daily temperature preference rhythm (TPR), which generates BTR. Here, we demonstrate dorsal clock networks that play essential roles in TPR. Dorsal neurons 2 (DN2s) are the main clock for TPR. We find that DN2s and posterior DN1s (DN1ps) contact and the extent of contacts increases during the day and that the silencing of DN2s or DN1ps leads to a lower temperature preference. The data suggest that temporal control of the microcircuit from DN2s to DN1ps contributes to TPR regulation. We also identify anterior DN1s (DN1as) as another important clock for TPR. Thus, we show that the DN networks predominantly control TPR and determine both a rhythmic pattern and preferred temperatures. The body temperature rhythm (BTR) is vital for maintaining homeostasis. Drosophila exhibit a daily temperature preference rhythm (TPR), which generates BTR. Chen et al. show that dorsal clock neurons in the brain form a time-dependent network and govern TPR by regulating a rhythmic pattern and a temperature setpoint.
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Affiliation(s)
- Shyh-Chi Chen
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Xin Tang
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Tadahiro Goda
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA 95616, USA
| | - Yujiro Umezaki
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA 95616, USA
| | - Abigail C Riley
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Manabu Sekiguchi
- Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Taishi Yoshii
- Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Fumika N Hamada
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA 95616, USA.
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14
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Yamaguchi ST, Tomita J, Kume K. Insulin signaling in clock neurons regulates sleep in Drosophila. Biochem Biophys Res Commun 2021; 591:44-49. [PMID: 34998032 DOI: 10.1016/j.bbrc.2021.12.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 12/26/2021] [Indexed: 12/12/2022]
Abstract
Sleep relates to numerous biological functions, including metabolism. Both dietary conditions and genes related to metabolism are known to affect sleep behavior. Insulin signaling is well conserved across species including the fruit fly and relates to both metabolism and sleep. However, the neural mechanism of sleep regulation by insulin signaling is poorly understood. Here, we report that insulin signaling in specific neurons regulates sleep in Drosophila melanogaster. We analyzed the sleep behavior of flies with the mutation in insulin-like ligands expressed in the brain and found that three insulin-like ligands participate in sleep regulation with some redundancy. We next used 21 Gal4 drivers to express a dominant-negative form of the insulin receptor (InR DN) in various neurons including circadian clock neurons, which express the clock gene, and the pars intercerebralis (PI). Inhibition of insulin signaling in the anterior dorsal neuron group 1 (DN1a) decreased sleep. Additionally, the same manipulation in PI also decreased sleep. Pan-neuronal induced expression of InR DN also decreased sleep. These results suggested that insulin signaling in DN1a and PI regulates sleep.
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Affiliation(s)
- Sho T Yamaguchi
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan.
| | - Jun Tomita
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan.
| | - Kazuhiko Kume
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan.
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15
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Reinhard N, Bertolini E, Saito A, Sekiguchi M, Yoshii T, Rieger D, Helfrich-Förster C. The lateral posterior clock neurons (LPN) of Drosophila melanogaster express three neuropeptides and have multiple connections within the circadian clock network and beyond. J Comp Neurol 2021; 530:1507-1529. [PMID: 34961936 DOI: 10.1002/cne.25294] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 11/12/2022]
Abstract
Drosophila's lateral posterior neurons (LPNs) belong to a small group of circadian clock neurons that is so far not characterized in detail. Thanks to a new highly specific split-Gal4 line, here we describe LPNs' morphology in fine detail, their synaptic connections, daily bimodal expression of neuropeptides, and propose a putative role of this cluster in controlling daily activity and sleep patterns. We found that the three LPNs are heterogeneous. Two of the neurons with similar morphology arborize in the superior medial and lateral protocerebrum and most likely promote sleep. One unique, possibly wakefulness-promoting, neuron with wider arborizations extends from the superior lateral protocerebrum toward the anterior optic tubercle. Both LPN types exhibit manifold connections with the other circadian clock neurons, especially with those that control the flies' morning and evening activity (M- and E-neurons, respectively). In addition, they form synaptic connections with neurons of the mushroom bodies, the fan-shaped body, and with many additional still unidentified neurons. We found that both LPN types rhythmically express three neuropeptides, Allostatin A, Allostatin C, and Diuretic Hormone 31 with maxima in the morning and the evening. The three LPN neuropeptides may, furthermore, signal to the insect hormonal center in the pars intercerebralis and contribute to rhythmic modulation of metabolism, feeding, and reproduction. We discuss our findings in the light of anatomical details gained by the recently published hemibrain of a single female fly on the electron microscopic level and of previous functional studies concerning the LPN. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Nils Reinhard
- Neurobiology and Genetics, Biocenter, University of Würzburg, Germany
| | - Enrico Bertolini
- Neurobiology and Genetics, Biocenter, University of Würzburg, Germany
| | - Aika Saito
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Manabu Sekiguchi
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Taishi Yoshii
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Dirk Rieger
- Neurobiology and Genetics, Biocenter, University of Würzburg, Germany
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16
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Decapentaplegic Acutely Defines the Connectivity of Central Pacemaker Neurons in Drosophila. J Neurosci 2021; 41:8338-8350. [PMID: 34429376 DOI: 10.1523/jneurosci.0397-21.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 07/12/2021] [Accepted: 08/11/2021] [Indexed: 11/21/2022] Open
Abstract
Rhythmic rest-activity cycles are controlled by an endogenous clock. In Drosophila, this clock resides in ∼150 neurons organized in clusters whose hierarchy changes in response to environmental conditions. The concerted activity of the circadian network is necessary for the adaptive responses to synchronizing environmental stimuli. Thus far, work was devoted to unravel the logic of the coordination of different clusters focusing on neurotransmitters and neuropeptides. We further explored communication in the adult male brain through ligands belonging to the bone morphogenetic protein (BMP) pathway. Herein we show that the lateral ventral neurons (LNvs) express the small morphogen decapentaplegic (DPP). DPP expression in the large LNvs triggered a period lengthening phenotype, the downregulation of which caused reduced rhythmicity and affected anticipation at dawn and dusk, underscoring DPP per se conveys time-of-day relevant information. Surprisingly, DPP expression in the large LNvs impaired circadian remodeling of the small LNv axonal terminals, likely through local modulation of the guanine nucleotide exchange factor Trio. These findings open the provocative possibility that the BMP pathway is recruited to strengthen/reduce the connectivity among specific clusters along the day and thus modulate the contribution of the clusters to the circadian network.SIGNIFICANCE STATEMENT The circadian clock relies on the communication between groups of so-called clock neurons to coordinate physiology and behavior to the optimal times across the day, predicting and adapting to a changing environment. The circadian network relies on neurotransmitters and neuropeptides to fine-tune connectivity among clock neurons and thus give rise to a coherent output. Herein we show that decapentaplegic, a ligand belonging to the BMP retrograde signaling pathway required for coordinated growth during development, is recruited by a group of circadian neurons in the adult brain to trigger structural remodeling of terminals on a daily basis.
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17
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Nettnin EA, Sallese TR, Nasseri A, Saurabh S, Cavanaugh DJ. Dorsal clock neurons in Drosophila sculpt locomotor outputs but are dispensable for circadian activity rhythms. iScience 2021; 24:103001. [PMID: 34505011 PMCID: PMC8413890 DOI: 10.1016/j.isci.2021.103001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/04/2021] [Accepted: 08/16/2021] [Indexed: 11/26/2022] Open
Abstract
The circadian system is comprised three components: a network of core clock cells in the brain that keeps time, input pathways that entrain clock cells to the environment, and output pathways that use this information to ensure appropriate timing of physiological and behavioral processes throughout the day. Core clock cells can be divided into molecularly distinct populations that likely make unique functional contributions. Here we clarify the role of the dorsal neuron 1 (DN1) population of clock neurons in the transmission of circadian information by the Drosophila core clock network. Using an intersectional genetic approach that allowed us to selectively and comprehensively target DN1 cells, we show that suppressing DN1 neuronal activity alters the magnitude of daily activity and sleep without affecting overt rhythmicity. This suggests that DN1 cells are dispensable for both the generation of circadian information and the propagation of this information across output circuits. Intersectional genetic approach targets DN1 cells comprehensively and selectively DN1p silencing alters distribution and amount of activity and sleep across the day DN1p cell firing is neither necessary nor sufficient for circadian activity rhythms DN1a silencing subtly alters total activity and sleep but leaves rhythmicity intact
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Affiliation(s)
- Ella A Nettnin
- Department of Biology, Loyola University Chicago, Chicago IL 60660, USA
| | - Thomas R Sallese
- Department of Biology, Loyola University Chicago, Chicago IL 60660, USA
| | - Anita Nasseri
- Department of Biology, Loyola University Chicago, Chicago IL 60660, USA
| | - Sumit Saurabh
- Department of Biology, Loyola University Chicago, Chicago IL 60660, USA
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18
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Ariyapala IS, Holsopple JM, Popodi EM, Hartwick DG, Kahsai L, Cook KR, Sokol NS. Identification of Split-GAL4 Drivers and Enhancers That Allow Regional Cell Type Manipulations of the Drosophila melanogaster Intestine. Genetics 2020; 216:891-903. [PMID: 32988987 PMCID: PMC7768249 DOI: 10.1534/genetics.120.303625] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 09/24/2020] [Indexed: 12/30/2022] Open
Abstract
The Drosophila adult midgut is a model epithelial tissue composed of a few major cell types with distinct regional identities. One of the limitations to its analysis is the lack of tools to manipulate gene expression based on these regional identities. To overcome this obstacle, we applied the intersectional split-GAL4 system to the adult midgut and report 653 driver combinations that label cells by region and cell type. We first identified 424 split-GAL4 drivers with midgut expression from ∼7300 drivers screened, and then evaluated the expression patterns of each of these 424 when paired with three reference drivers that report activity specifically in progenitor cells, enteroendocrine cells, or enterocytes. We also evaluated a subset of the drivers expressed in progenitor cells for expression in enteroblasts using another reference driver. We show that driver combinations can define novel cell populations by identifying a driver that marks a distinct subset of enteroendocrine cells expressing genes usually associated with progenitor cells. The regional cell type patterns associated with the entire set of driver combinations are documented in a freely available website, providing information for the design of thousands of additional driver combinations to experimentally manipulate small subsets of intestinal cells. In addition, we show that intestinal enhancers identified with the split-GAL4 system can confer equivalent expression patterns on other transgenic reporters. Altogether, the resource reported here will enable more precisely targeted gene expression for studying intestinal processes, epithelial cell functions, and diseases affecting self-renewing tissues.
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Affiliation(s)
| | - Jessica M Holsopple
- Department of Biology, Indiana University, Bloomington, Indiana 47405
- Bloomington Drosophila Stock Center, Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Ellen M Popodi
- Bloomington Drosophila Stock Center, Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Dalton G Hartwick
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Lily Kahsai
- Bloomington Drosophila Stock Center, Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Kevin R Cook
- Bloomington Drosophila Stock Center, Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Nicholas S Sokol
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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19
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Luan H, Diao F, Scott RL, White BH. The Drosophila Split Gal4 System for Neural Circuit Mapping. Front Neural Circuits 2020; 14:603397. [PMID: 33240047 PMCID: PMC7680822 DOI: 10.3389/fncir.2020.603397] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 10/06/2020] [Indexed: 12/22/2022] Open
Abstract
The diversity and dense interconnectivity of cells in the nervous system present a huge challenge to understanding how brains work. Recent progress toward such understanding, however, has been fuelled by the development of techniques for selectively monitoring and manipulating the function of distinct cell types-and even individual neurons-in the brains of living animals. These sophisticated techniques are fundamentally genetic and have found their greatest application in genetic model organisms, such as the fruit fly Drosophila melanogaster. Drosophila combines genetic tractability with a compact, but cell-type rich, nervous system and has been the incubator for a variety of methods of neuronal targeting. One such method, called Split Gal4, is playing an increasingly important role in mapping neural circuits in the fly. In conjunction with functional perturbations and behavioral screens, Split Gal4 has been used to characterize circuits governing such activities as grooming, aggression, and mating. It has also been leveraged to comprehensively map and functionally characterize cells composing important brain regions, such as the central complex, lateral horn, and the mushroom body-the latter being the insect seat of learning and memory. With connectomics data emerging for both the larval and adult brains of Drosophila, Split Gal4 is also poised to play an important role in characterizing neurons of interest based on their connectivity. We summarize the history and current state of the Split Gal4 method and indicate promising areas for further development or future application.
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Affiliation(s)
| | | | | | - Benjamin H. White
- Laboratory of Molecular Biology, National Institute of Mental Health, NIH, Bethesda, MD, United States
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20
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Marin EC, Büld L, Theiss M, Sarkissian T, Roberts RJV, Turnbull R, Tamimi IFM, Pleijzier MW, Laursen WJ, Drummond N, Schlegel P, Bates AS, Li F, Landgraf M, Costa M, Bock DD, Garrity PA, Jefferis GSXE. Connectomics Analysis Reveals First-, Second-, and Third-Order Thermosensory and Hygrosensory Neurons in the Adult Drosophila Brain. Curr Biol 2020; 30:3167-3182.e4. [PMID: 32619476 PMCID: PMC7443704 DOI: 10.1016/j.cub.2020.06.028] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 05/08/2020] [Accepted: 06/08/2020] [Indexed: 01/08/2023]
Abstract
Animals exhibit innate and learned preferences for temperature and humidity-conditions critical for their survival and reproduction. Leveraging a whole-brain electron microscopy volume, we studied the adult Drosophila melanogaster circuitry associated with antennal thermo- and hygrosensory neurons. We have identified two new target glomeruli in the antennal lobe, in addition to the five known ones, and the ventroposterior projection neurons (VP PNs) that relay thermo- and hygrosensory information to higher brain centers, including the mushroom body and lateral horn, seats of learned and innate behavior. We present the first connectome of a thermo- and hygrosensory neuropil, the lateral accessory calyx (lACA), by reconstructing neurons downstream of heating- and cooling-responsive VP PNs. A few mushroom body-intrinsic neurons solely receive thermosensory input from the lACA, while most receive additional olfactory and thermo- and/or hygrosensory PN inputs. Furthermore, several classes of lACA-associated neurons form a local network with outputs to other brain neuropils, suggesting that the lACA serves as a hub for thermo- and hygrosensory circuitry. For example, DN1a neurons link thermosensory PNs in the lACA to the circadian clock via the accessory medulla. Finally, we survey strongly connected downstream partners of VP PNs across the protocerebrum; these include a descending neuron targeted by dry-responsive VP PNs, meaning that just two synapses might separate hygrosensory inputs from motor circuits. These data provide a comprehensive first- and second-order layer analysis of Drosophila thermo- and hygrosensory systems and an initial survey of third-order neurons that could directly modulate behavior.
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Affiliation(s)
- Elizabeth C Marin
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Laurin Büld
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Maria Theiss
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | | | | | - Robert Turnbull
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Imaan F M Tamimi
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Markus W Pleijzier
- Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire CB2 0QH, UK
| | - Willem J Laursen
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Nik Drummond
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Philipp Schlegel
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK; Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire CB2 0QH, UK
| | - Alexander S Bates
- Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire CB2 0QH, UK
| | - Feng Li
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Marta Costa
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Davi D Bock
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA; Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Paul A Garrity
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Gregory S X E Jefferis
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK; Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire CB2 0QH, UK.
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