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Maiellaro I. In Vivo cAMP Dynamics in Drosophila Larval Neurons. Methods Mol Biol 2022; 2483:181-194. [PMID: 35286676 DOI: 10.1007/978-1-0716-2245-2_11] [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] [Indexed: 06/14/2023]
Abstract
Cyclic adenosine monophosphate (cAMP) is a universal second messenger that mediates a myriad of cell functions across all kingdoms of life.The ability to monitor intracellular changes of cAMP concentration in living cells using FRET-based biosensors is proving to be of paramount importance to unraveling the sophisticated organization of cAMP signaling.Here we describe the deployment of the fruit fly Drosophila melanogaster, specifically the third instar larval stage, as an in vivo model to study the spatio-temporal dynamics of cAMP in neurons. The ubiquity of cAMP signaling and conservation of fundamental mechanisms across species ensures relevance to vertebrate neurons while providing a more structurally and ethically simple model.
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Affiliation(s)
- Isabella Maiellaro
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, UK.
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Maiellaro I, Lohse MJ, Kittel RJ, Calebiro D. cAMP Signals in Drosophila Motor Neurons Are Confined to Single Synaptic Boutons. Cell Rep 2017; 17:1238-1246. [PMID: 27783939 PMCID: PMC5098120 DOI: 10.1016/j.celrep.2016.09.090] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 08/29/2016] [Accepted: 09/27/2016] [Indexed: 11/03/2022] Open
Abstract
The second messenger cyclic AMP (cAMP) plays an important role in synaptic plasticity. Although there is evidence for local control of synaptic transmission and plasticity, it is less clear whether a similar spatial confinement of cAMP signaling exists. Here, we suggest a possible biophysical basis for the site-specific regulation of synaptic plasticity by cAMP, a highly diffusible small molecule that transforms the physiology of synapses in a local and specific manner. By exploiting the octopaminergic system of Drosophila, which mediates structural synaptic plasticity via a cAMP-dependent pathway, we demonstrate the existence of local cAMP signaling compartments of micrometer dimensions within single motor neurons. In addition, we provide evidence that heterogeneous octopamine receptor localization, coupled with local differences in phosphodiesterase activity, underlies the observed differences in cAMP signaling in the axon, cell body, and boutons. Boutons, axon, and cell body are independent cAMP signaling compartments Receptors and PDEs are responsible for the compartmentalization of cAMP cAMP does not propagate from the bouton to the cell body Local cAMP increases provides a basis for site-specific control of synaptic plasticity
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Affiliation(s)
- Isabella Maiellaro
- Institute of Pharmacology and Toxicology and Rudolf Virchow Center, University of Würzburg, Versbacher Strasse 9, 97078 Würzburg, Germany.
| | - Martin J Lohse
- Institute of Pharmacology and Toxicology and Rudolf Virchow Center, University of Würzburg, Versbacher Strasse 9, 97078 Würzburg, Germany
| | - Robert J Kittel
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Röntgenring 9, 97070 Würzburg, Germany.
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology and Rudolf Virchow Center, University of Würzburg, Versbacher Strasse 9, 97078 Würzburg, Germany.
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Van Vactor D, Sigrist SJ. Presynaptic morphogenesis, active zone organization and structural plasticity in Drosophila. Curr Opin Neurobiol 2017; 43:119-129. [PMID: 28388491 DOI: 10.1016/j.conb.2017.03.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 03/06/2017] [Accepted: 03/08/2017] [Indexed: 12/31/2022]
Abstract
Effective adaptation of neural circuit function to a changing environment requires many forms of plasticity. Among these, structural plasticity is one of the most durable, and is also an intrinsic part of the developmental logic for the formation and refinement of synaptic connectivity. Structural plasticity of presynaptic sites can involve the addition, remodeling, or removal of pre- and post-synaptic elements. However, this requires coordination of morphogenesis and assembly of the subcellular machinery for neurotransmitter release within the presynaptic neuron, as well as coordination of these events with the postsynaptic cell. While much progress has been made in revealing the cell biological mechanisms of postsynaptic structural plasticity, our understanding of presynaptic mechanisms is less complete.
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Affiliation(s)
- David Van Vactor
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Okinawa Institute of Science and Technology, Graduate University, Tancha 1919-1, Onna-son, Okinawa, Japan.
| | - Stephan J Sigrist
- Institut für Biologie/Genetik and NeuroCure, Freie Universität Berlin, Takustrasse 6, D-14195 Berlin, Germany.
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Martin CA, Myers KM, Chen A, Martin NT, Barajas A, Schweizer FE, Krantz DE. Ziram, a pesticide associated with increased risk for Parkinson's disease, differentially affects the presynaptic function of aminergic and glutamatergic nerve terminals at the Drosophila neuromuscular junction. Exp Neurol 2016; 275 Pt 1:232-41. [PMID: 26439313 PMCID: PMC4688233 DOI: 10.1016/j.expneurol.2015.09.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 09/04/2015] [Accepted: 09/26/2015] [Indexed: 12/29/2022]
Abstract
Multiple populations of aminergic neurons are affected in Parkinson's disease (PD), with serotonergic and noradrenergic loci responsible for some non-motor symptoms. Environmental toxins, such as the dithiocarbamate fungicide ziram, significantly increase the risk of developing PD and the attendant spectrum of both motor and non-motor symptoms. The mechanisms by which ziram and other environmental toxins increase the risk of PD, and the potential effects of these toxins on aminergic neurons, remain unclear. To determine the relative effects of ziram on the synaptic function of aminergic versus non-aminergic neurons, we used live-imaging at the Drosophila melanogaster larval neuromuscular junction (NMJ). In contrast to nearly all other studies of this model synapse, we imaged presynaptic function at both glutamatergic Type Ib and aminergic Type II boutons, the latter responsible for storage and release of octopamine, the invertebrate equivalent of noradrenalin. To quantify the kinetics of exo- and endo-cytosis, we employed an acid-sensitive form of GFP fused to the Drosophila vesicular monoamine transporter (DVMAT-pHluorin). Additional genetic probes were used to visualize intracellular calcium flux (GCaMP) and voltage changes (ArcLight). We find that at glutamatergic Type Ib terminals, exposure to ziram increases exocytosis and inhibits endocytosis. By contrast, at octopaminergic Type II terminals, ziram has no detectable effect on exocytosis and dramatically inhibits endocytosis. In contrast to other reports on the neuronal effects of ziram, these effects do not appear to result from perturbation of the Ubiquitin Proteasome System (UPS) or calcium homeostasis. Unexpectedly, ziram also caused spontaneous and synchronized bursts of calcium influx (measured by GCaMP) and electrical activity (measured by ArcLight) at aminergic Type II, but not glutamatergic Type Ib, nerve terminals. These events are sensitive to both tetrodotoxin and cadmium chloride, and thus appear to represent spontaneous depolarizations followed by calcium influx into Type II terminals. We speculate that the differential effects of ziram on Type II versus Type Ib terminals may be relevant to the specific sensitivity of aminergic neurons in PD, and suggest that changes in neuronal excitability could contribute to the increased risk for PD caused by exposure to ziram. We also suggest that the fly NMJ will be useful to explore the synaptic effects of other pesticides associated with an increased risk of PD.
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Affiliation(s)
- Ciara A Martin
- Department of Psychiatry and Biobehavioral Sciences, Hatos Center for Neuropharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, United States; UCLA Interdepartmental Program in Molecular Toxicology, Los Angeles, CA 90095, United States.
| | - Katherine M Myers
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, United States; UCLA Interdepartmental Program for Neuroscience, Los Angeles, CA 90095, United States.
| | - Audrey Chen
- Department of Psychiatry and Biobehavioral Sciences, Hatos Center for Neuropharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, United States; Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, United States.
| | - Nathan T Martin
- UCLA Biomedical Physics Interdepartmental Graduate Program, Los Angeles, CA 90095, United States.
| | - Angel Barajas
- Department of Psychiatry and Biobehavioral Sciences, Hatos Center for Neuropharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, United States.
| | - Felix E Schweizer
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, United States; UCLA Interdepartmental Program for Neuroscience, Los Angeles, CA 90095, United States.
| | - David E Krantz
- Department of Psychiatry and Biobehavioral Sciences, Hatos Center for Neuropharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, United States; UCLA Interdepartmental Program in Molecular Toxicology, Los Angeles, CA 90095, United States; UCLA Interdepartmental Program for Neuroscience, Los Angeles, CA 90095, United States.
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Olsen DP, Keshishian H. Monitoring membrane excitability in Drosophila expressing modified shaker constructs. Cold Spring Harb Protoc 2012; 2012:226-30. [PMID: 22301649 DOI: 10.1101/pdb.prot067801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The Drosophila neuromuscular junction (NMJ) ranks as one of the preeminent model systems for studying synaptic development, function, and plasticity. This protocol describes the use of the two-electrode voltage clamp (TEVC) to examine potassium (K(+)) currents mediated by voltage-gated ion channels, and gives several genetic and pharmacological methods that are used to study the currents. Drosophila larval muscle fibers possess three major K(+) currents. One of these, a fast voltage-activating and inactivating I(A) current, is mediated by the Shaker channel. The Shaker channel is characterized by its sensitivity to the drug 4-aminopyridine (4-AP). Two useful transgenic tools for altering membrane excitability have been developed by making specific modifications of the Shaker channel; their use is described here.
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