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Le JQ, Ma D, Dai X, Rosbash M. Light and dopamine impact two circadian neurons to promote morning wakefulness. Curr Biol 2024; 34:3941-3954.e4. [PMID: 39142287 DOI: 10.1016/j.cub.2024.07.056] [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: 02/05/2024] [Revised: 05/13/2024] [Accepted: 07/16/2024] [Indexed: 08/16/2024]
Abstract
In both mammals and flies, circadian brain neurons orchestrate physiological oscillations and behaviors like wake and sleep-these neurons can be subdivided by morphology and by gene expression patterns. Recent single-cell sequencing studies identified 17 Drosophila circadian neuron groups. One of these includes only two lateral neurons (LNs), which are marked by the expression of the neuropeptide ion transport peptide (ITP). Although these two ITP+ LNs have long been grouped with five other circadian evening activity cells, inhibiting the two neurons alone strongly reduces morning activity, indicating that they also have a prominent morning function. As dopamine signaling promotes activity in Drosophila, like in mammals, we considered that dopamine might influence this morning activity function. Moreover, the ITP+ LNs express higher mRNA levels than other LNs of the type 1-like dopamine receptor Dop1R1. Consistent with the importance of Dop1R1, cell-specific CRISPR-Cas9 mutagenesis of this receptor in the two ITP+ LNs renders flies significantly less active in the morning, and ex vivo live imaging shows Dop1R1-dependent cyclic AMP (cAMP) responses to dopamine in these two neurons. Notably, the response is more robust in the morning, reflecting higher morning Dop1R1 mRNA levels in the two neurons. As mRNA levels are not elevated in constant darkness, this suggests light-dependent upregulation of morning Dop1R1 transcript levels. Taken together with the enhanced morning cAMP response to dopamine, the data indicate how light and dopamine promote morning wakefulness in flies, mimicking the important effect of light on morning wakefulness in humans.
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Affiliation(s)
- Jasmine Quynh Le
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02453, USA
| | - Dingbang Ma
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02453, USA; Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China
| | - Xihuimin Dai
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02453, USA
| | - Michael Rosbash
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02453, USA.
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Le JQ, Ma D, Dai X, Rosbash M. Light and dopamine impact two circadian neurons to promote morning wakefulness. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.04.583333. [PMID: 38496661 PMCID: PMC10942368 DOI: 10.1101/2024.03.04.583333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
In both mammals and flies, circadian brain neurons orchestrate physiological oscillations and behaviors like wake and sleep; these neurons can be subdivided by morphology and by gene expression patterns. Recent single-cell sequencing studies identified 17 Drosophila circadian neuron groups. One of these include only two lateral neurons (LNs), which are marked by the expression of the neuropeptide ion transport peptide (ITP). Although these two ITP+ LNs have long been grouped with five other circadian evening activity cells, inhibiting the two neurons alone strongly reduces morning activity; this indicates that they are prominent morning neurons. As dopamine signaling promotes activity in Drosophila like in mammals, we considered that dopamine might influence this morning activity function. Moreover, the ITP+ LNs express higher mRNA levels than other LNs of the type 1-like dopamine receptor Dop1R1. Consistent with the importance of Dop1R1, CRISPR/Cas9 mutagenesis of this receptor only in the two ITP+ LNs renders flies significantly less active in the morning, and ex vivo live imaging shows that dopamine increases cAMP levels in these two neurons; cell-specific mutagenesis of Dop1R1 eliminates this cAMP response to dopamine. Notably, the response is more robust in the morning, reflecting higher morning Dop1R1 mRNA levels in the two neurons. As morning levels are not elevated in constant darkness, this suggests light-dependent upregulation of morning Dop1R1 transcript levels. Taken together with enhanced morning cAMP response to dopamine, the data indicate how light stimulates morning wakefulness in flies, which mimics the important effect of light on morning wakefulness in humans.
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Affiliation(s)
- Jasmine Quynh Le
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Dingbang Ma
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, Massachusetts 02453, USA
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Xihuimin Dai
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Michael Rosbash
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, Massachusetts 02453, USA
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Davis RL. Learning and memory using Drosophila melanogaster: a focus on advances made in the fifth decade of research. Genetics 2023; 224:iyad085. [PMID: 37212449 PMCID: PMC10411608 DOI: 10.1093/genetics/iyad085] [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: 02/16/2023] [Accepted: 05/03/2023] [Indexed: 05/23/2023] Open
Abstract
In the last decade, researchers using Drosophila melanogaster have made extraordinary progress in uncovering the mysteries underlying learning and memory. This progress has been propelled by the amazing toolkit available that affords combined behavioral, molecular, electrophysiological, and systems neuroscience approaches. The arduous reconstruction of electron microscopic images resulted in a first-generation connectome of the adult and larval brain, revealing complex structural interconnections between memory-related neurons. This serves as substrate for future investigations on these connections and for building complete circuits from sensory cue detection to changes in motor behavior. Mushroom body output neurons (MBOn) were discovered, which individually forward information from discrete and non-overlapping compartments of the axons of mushroom body neurons (MBn). These neurons mirror the previously discovered tiling of mushroom body axons by inputs from dopamine neurons and have led to a model that ascribes the valence of the learning event, either appetitive or aversive, to the activity of different populations of dopamine neurons and the balance of MBOn activity in promoting avoidance or approach behavior. Studies of the calyx, which houses the MBn dendrites, have revealed a beautiful microglomeruluar organization and structural changes of synapses that occur with long-term memory (LTM) formation. Larval learning has advanced, positioning it to possibly lead in producing new conceptual insights due to its markedly simpler structure over the adult brain. Advances were made in how cAMP response element-binding protein interacts with protein kinases and other transcription factors to promote the formation of LTM. New insights were made on Orb2, a prion-like protein that forms oligomers to enhance synaptic protein synthesis required for LTM formation. Finally, Drosophila research has pioneered our understanding of the mechanisms that mediate permanent and transient active forgetting, an important function of the brain along with acquisition, consolidation, and retrieval. This was catalyzed partly by the identification of memory suppressor genes-genes whose normal function is to limit memory formation.
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Affiliation(s)
- Ronald L Davis
- Department of Neuroscience, Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, 130 Scripps Way, Jupiter, FL 33458, USA
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Chen N, Zhang Y, Adel M, Kuklin EA, Reed ML, Mardovin JD, Bakthavachalu B, VijayRaghavan K, Ramaswami M, Griffith LC. Local translation provides the asymmetric distribution of CaMKII required for associative memory formation. Curr Biol 2022; 32:2730-2738.e5. [PMID: 35545085 DOI: 10.1016/j.cub.2022.04.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/18/2022] [Accepted: 04/14/2022] [Indexed: 10/18/2022]
Abstract
How compartment-specific local proteomes are generated and maintained is inadequately understood, particularly in neurons, which display extreme asymmetries. Here we show that local enrichment of Ca2+/calmodulin-dependent protein kinase II (CaMKII) in axons of Drosophila mushroom body neurons is necessary for cellular plasticity and associative memory formation. Enrichment is achieved via enhanced axoplasmic translation of CaMKII mRNA, through a mechanism requiring the RNA-binding protein Mub and a 23-base Mub-recognition element in the CaMKII 3' UTR. Perturbation of either dramatically reduces axonal, but not somatic, CaMKII protein without altering the distribution or amount of mRNA in vivo, and both are necessary and sufficient to enhance axonal translation of reporter mRNA. Together, these data identify elevated levels of translation of an evenly distributed mRNA as a novel strategy for generating subcellular biochemical asymmetries. They further demonstrate the importance of distributional asymmetry in the computational and biological functions of neurons.
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Affiliation(s)
- Nannan Chen
- Department of Biology, Volen National Center for Complex Systems, Brandeis University, 415 South Street, Waltham, MA 02454-9110, USA
| | - Yunpeng Zhang
- Department of Biology, Volen National Center for Complex Systems, Brandeis University, 415 South Street, Waltham, MA 02454-9110, USA
| | - Mohamed Adel
- Department of Biology, Volen National Center for Complex Systems, Brandeis University, 415 South Street, Waltham, MA 02454-9110, USA
| | - Elena A Kuklin
- Department of Biology, Volen National Center for Complex Systems, Brandeis University, 415 South Street, Waltham, MA 02454-9110, USA
| | - Martha L Reed
- Department of Biology, Volen National Center for Complex Systems, Brandeis University, 415 South Street, Waltham, MA 02454-9110, USA
| | - Jacob D Mardovin
- Department of Biology, Volen National Center for Complex Systems, Brandeis University, 415 South Street, Waltham, MA 02454-9110, USA
| | - Baskar Bakthavachalu
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore 560065, India; School of Basic Science, Indian Institute of Technology Mandi, Mandi, India
| | - K VijayRaghavan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore 560065, India; School of Basic Science, Indian Institute of Technology Mandi, Mandi, India
| | - Mani Ramaswami
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology and School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland; National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore 560065, India; School of Basic Science, Indian Institute of Technology Mandi, Mandi, India
| | - Leslie C Griffith
- Department of Biology, Volen National Center for Complex Systems, Brandeis University, 415 South Street, Waltham, MA 02454-9110, USA.
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