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Cherepanov S, Heitzmann L, Fontanaud P, Guillou A, Galibert E, Campos P, Mollard P, Martin AO. Prolactin blood concentration relies on the scalability of the TIDA neurons' network efficiency in vivo. iScience 2024; 27:109876. [PMID: 38799572 PMCID: PMC11126972 DOI: 10.1016/j.isci.2024.109876] [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: 10/06/2023] [Revised: 02/09/2024] [Accepted: 04/29/2024] [Indexed: 05/29/2024] Open
Abstract
Our understanding and management of reproductive health and related disorders such as infertility, menstrual irregularities, and pituitary disorders depend on understanding the intricate sex-specific mechanisms governing prolactin secretion. Using ex vivo experiments in acute slices, in parallel with in vivo calcium imaging (GRIN lens technology), we found that dopamine neurons inhibiting PRL secretion (TIDA), organize as functional networks both in and ex vivo. We defined an index of efficiency of networking (Ieff) using the duration of calcium events and the ability to form plastic economic networks. It determined TIDA neurons' ability to inhibit PRL secretion in vivo. Ieff variations in both sexes demonstrated TIDA neurons' adaptability to physiological changes. A variation in the number of active neurons contributing to the network explains the sexual dimorphism in basal [PRL]blood secretion patterns. These sex-specific differences in neuronal activity and network organization contribute to the understanding of hormone regulation.
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Affiliation(s)
- Stanislav Cherepanov
- Team for networks and rhythms in endocrine glands. Institute of Functional Genomics, CNRS, INSERM. Montpellier, 34094 Occitanie, France
| | - Louise Heitzmann
- Sex and speciation team, department of genome, phenome and environment. Montpellier Institute of Evolution Science, CNRS. Montpellier, 34090 Occitanie, France
| | - Pierre Fontanaud
- Team for networks and rhythms in endocrine glands. Institute of Functional Genomics, CNRS, INSERM. Montpellier, 34094 Occitanie, France
| | - Anne Guillou
- Team for networks and rhythms in endocrine glands. Institute of Functional Genomics, CNRS, INSERM. Montpellier, 34094 Occitanie, France
| | - Evelyne Galibert
- Team for networks and rhythms in endocrine glands. Institute of Functional Genomics, CNRS, INSERM. Montpellier, 34094 Occitanie, France
| | - Pauline Campos
- Department of Mathematics and Statistics, Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK
| | - Patrice Mollard
- Team for networks and rhythms in endocrine glands. Institute of Functional Genomics, CNRS, INSERM. Montpellier, 34094 Occitanie, France
| | - Agnès O. Martin
- Team for networks and rhythms in endocrine glands. Institute of Functional Genomics, CNRS, INSERM. Montpellier, 34094 Occitanie, France
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2
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Deshpande SA, Rohrbach EW, Asuncion JD, Harrigan J, Eamani A, Schlingmann EH, Suto DJ, Lee PT, Schweizer FE, Bellen HJ, Krantz DE. Regulation of Drosophila oviduct muscle contractility by octopamine. iScience 2022; 25:104697. [PMID: 35880044 PMCID: PMC9307614 DOI: 10.1016/j.isci.2022.104697] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 04/21/2022] [Accepted: 06/27/2022] [Indexed: 11/20/2022] Open
Abstract
Octopamine is essential for egg-laying in Drosophila melanogaster, but the neuronal pathways and receptors by which it regulates visceral muscles in the reproductive tract are not known. We find that the two octopamine receptors that have been previously implicated in egg-laying–OAMB and Octβ2R-are expressed in octopaminergic and glutamatergic neurons that project to the reproductive tract, peripheral ppk(+) neurons within the reproductive tract and epithelial cells that line the lumen of the oviducts. Further optogenetic and mutational analyses indicate that octopamine regulates both oviduct contraction and relaxation via Octβ2 and OAMB respectively. Interactions with glutamatergic pathways modify the effects of octopamine. Octopaminergic activation of Octβ2R on glutamatergic processes provides a possible mechanism by which octopamine initiates lateral oviduct contractions. We speculate that aminergic pathways in the oviposition circuit may be comparable to some of the mechanisms that regulate visceral muscle contractility in mammals. The receptors Octβ2 and OAMB mediate oviduct muscle contraction and relaxation The receptors are detectably expressed in neurons and epithelia but not muscle cells The control of visceral muscles in flies and mammals may share common features
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Affiliation(s)
- Sonali A. Deshpande
- Department of Psychiatry and Biobehavioral Sciences, Hatos Center for Neuropharmacology, Gonda (Goldschmied) Neuroscience and Genetics Research Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Ethan W. Rohrbach
- Interdepartmental Program in Neuroscience, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - James D. Asuncion
- Medical Scientist Training Program, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Jenna Harrigan
- Interdepartmental Program in Molecular Toxicology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Aditya Eamani
- Department of Psychiatry and Biobehavioral Sciences, Hatos Center for Neuropharmacology, Gonda (Goldschmied) Neuroscience and Genetics Research Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Ellery H. Schlingmann
- Department of Psychiatry and Biobehavioral Sciences, Hatos Center for Neuropharmacology, Gonda (Goldschmied) Neuroscience and Genetics Research Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Daniel J. Suto
- Department of Psychiatry and Biobehavioral Sciences, Hatos Center for Neuropharmacology, Gonda (Goldschmied) Neuroscience and Genetics Research Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Felix E. Schweizer
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Hugo J. Bellen
- Department of Molecular and Human Genetics, Department of Neuroscience, Baylor College of Medicine, Howard Hughes Medical Institute, Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030, USA
| | - David E. Krantz
- Department of Psychiatry and Biobehavioral Sciences, Hatos Center for Neuropharmacology, Gonda (Goldschmied) Neuroscience and Genetics Research Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Corresponding author
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3
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Ueda A, O'Harrow TCDG, Xing X, Ehaideb S, Manak JR, Wu CF. Abnormal larval neuromuscular junction morphology and physiology in Drosophila prickle isoform mutants with known axonal transport defects and adult seizure behavior. J Neurogenet 2022; 36:65-73. [PMID: 35775303 DOI: 10.1080/01677063.2022.2093353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Previous studies have demonstrated the striking mutational effects of the Drosophila planar cell polarity gene prickle (pk) on larval motor axon microtubule-mediated vesicular transport and on adult epileptic behavior associated with neuronal circuit hyperexcitability. Mutant alleles of the prickle-prickle (pkpk) and prickle-spiny-legs (pksple) isoforms (hereafter referred to as pk and sple alleles, respectively) exhibit differential phenotypes. While both pk and sple affect larval motor axon transport, only sple confers motor circuit and behavior hyperexcitability. However, mutations in the two isoforms apparently counteract to ameliorate adult motor circuit and behavioral hyperexcitability in heteroallelic pkpk/pksple flies. We have further investigated the consequences of altered axonal transport in the development and function of the larval neuromuscular junction (NMJ). We uncovered robust dominant phenotypes in both pk and sple alleles, including synaptic terminal overgrowth (as revealed by anti-HRP and -Dlg immunostaining) and poor vesicle release synchronicity (as indicated by synaptic bouton focal recording). However, we observed recessive alteration of synaptic transmission only in pk/pk larvae, i.e. increased excitatory junctional potential (EJP) amplitude in pk/pk but not in pk/+ or sple/sple. Interestingly, for motor terminal excitability sustained by presynaptic Ca2+ channels, both pk and sple exerted strong effects to produce prolonged depolarization. Notably, only sple acted dominantly whereas pk/+ appeared normal, but was able to suppress the sple phenotypes, i.e. pk/sple appeared normal. Our observations contrast the differential roles of the pk and sple isoforms and highlight their distinct, variable phenotypic expression in the various structural and functional aspects of the larval NMJ.
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Affiliation(s)
- Atsushi Ueda
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | | | - Xiaomin Xing
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Salleh Ehaideb
- Department of Biology, University of Iowa, Iowa City, IA, USA.,Genetics Ph.D. Program, University of Iowa, Iowa City, IA, USA
| | - J Robert Manak
- Department of Biology, University of Iowa, Iowa City, IA, USA.,Genetics Ph.D. Program, University of Iowa, Iowa City, IA, USA.,Department of Pediatrics, University of Iowa, Iowa City, IA, USA.,Neuroscience Ph.D. Program, University of Iowa, Iowa City, IA, USA
| | - Chun-Fang Wu
- Department of Biology, University of Iowa, Iowa City, IA, USA.,Genetics Ph.D. Program, University of Iowa, Iowa City, IA, USA.,Neuroscience Ph.D. Program, University of Iowa, Iowa City, IA, USA
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4
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Knodel MM, Dutta Roy R, Wittum G. Influence of T-Bar on Calcium Concentration Impacting Release Probability. Front Comput Neurosci 2022; 16:855746. [PMID: 35586479 PMCID: PMC9108211 DOI: 10.3389/fncom.2022.855746] [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: 01/15/2022] [Accepted: 03/09/2022] [Indexed: 11/25/2022] Open
Abstract
The relation of form and function, namely the impact of the synaptic anatomy on calcium dynamics in the presynaptic bouton, is a major challenge of present (computational) neuroscience at a cellular level. The Drosophila larval neuromuscular junction (NMJ) is a simple model system, which allows studying basic effects in a rather simple way. This synapse harbors several special structures. In particular, in opposite to standard vertebrate synapses, the presynaptic boutons are rather large, and they have several presynaptic zones. In these zones, different types of anatomical structures are present. Some of the zones bear a so-called T-bar, a particular anatomical structure. The geometric form of the T-bar resembles the shape of the letter “T” or a table with one leg. When an action potential arises, calcium influx is triggered. The probability of vesicle docking and neurotransmitter release is superlinearly proportional to the concentration of calcium close to the vesicular release site. It is tempting to assume that the T-bar causes some sort of calcium accumulation and hence triggers a higher release probability and thus enhances neurotransmitter exocytosis. In order to study this influence in a quantitative manner, we constructed a typical T-bar geometry and compared the calcium concentration close to the active zones (AZs). We compared the case of synapses with and without T-bars. Indeed, we found a substantial influence of the T-bar structure on the presynaptic calcium concentrations close to the AZs, indicating that this anatomical structure increases vesicle release probability. Therefore, our study reveals how the T-bar zone implies a strong relation between form and function. Our study answers the question of experimental studies (namely “Wichmann and Sigrist, Journal of neurogenetics 2010”) concerning the sense of the anatomical structure of the T-bar.
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Affiliation(s)
- Markus M. Knodel
- Goethe Center for Scientific Computing (GCSC), Goethe Universität Frankfurt, Frankfurt, Germany
- *Correspondence: Markus M. Knodel ; orcid.org/0000-0001-8739-0803
| | | | - Gabriel Wittum
- Goethe Center for Scientific Computing (GCSC), Goethe Universität Frankfurt, Frankfurt, Germany
- Applied Mathematics and Computational Science, Computer, Electrical and Mathematical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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5
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Philyaw TJ, Rothenfluh A, Titos I. The Use of Drosophila to Understand Psychostimulant Responses. Biomedicines 2022; 10:119. [PMID: 35052798 PMCID: PMC8773124 DOI: 10.3390/biomedicines10010119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/31/2021] [Accepted: 12/31/2021] [Indexed: 01/27/2023] Open
Abstract
The addictive properties of psychostimulants such as cocaine, amphetamine, methamphetamine, and methylphenidate are based on their ability to increase dopaminergic neurotransmission in the reward system. While cocaine and methamphetamine are predominately used recreationally, amphetamine and methylphenidate also work as effective therapeutics to treat symptoms of disorders including attention deficit and hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Although both the addictive properties of psychostimulant drugs and their therapeutic efficacy are influenced by genetic variation, very few genes that regulate these processes in humans have been identified. This is largely due to population heterogeneity which entails a requirement for large samples. Drosophila melanogaster exhibits similar psychostimulant responses to humans, a high degree of gene conservation, and allow performance of behavioral assays in a large population. Additionally, amphetamine and methylphenidate reduce impairments in fly models of ADHD-like behavior. Therefore, Drosophila represents an ideal translational model organism to tackle the genetic components underlying the effects of psychostimulants. Here, we break down the many assays that reliably quantify the effects of cocaine, amphetamine, methamphetamine, and methylphenidate in Drosophila. We also discuss how Drosophila is an efficient and cost-effective model organism for identifying novel candidate genes and molecular mechanisms involved in the behavioral responses to psychostimulant drugs.
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Affiliation(s)
- Travis James Philyaw
- Molecular Biology Graduate Program, University of Utah, Salt Lake City, UT 84112, USA;
| | - Adrian Rothenfluh
- Department of Psychiatry, Huntsman Mental Health Institute, University of Utah, Salt Lake City, UT 84108, USA
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
- Department of Neurobiology, University of Utah, Salt Lake City, UT 84132, USA
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Iris Titos
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
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6
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Li ES, Saha MS. Optimizing Calcium Detection Methods in Animal Systems: A Sandbox for Synthetic Biology. Biomolecules 2021; 11:343. [PMID: 33668387 PMCID: PMC7996158 DOI: 10.3390/biom11030343] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/19/2021] [Accepted: 02/21/2021] [Indexed: 12/16/2022] Open
Abstract
Since the 1970s, the emergence and expansion of novel methods for calcium ion (Ca2+) detection have found diverse applications in vitro and in vivo across a series of model animal systems. Matched with advances in fluorescence imaging techniques, the improvements in the functional range and stability of various calcium indicators have significantly enhanced more accurate study of intracellular Ca2+ dynamics and its effects on cell signaling, growth, differentiation, and regulation. Nonetheless, the current limitations broadly presented by organic calcium dyes, genetically encoded calcium indicators, and calcium-responsive nanoparticles suggest a potential path toward more rapid optimization by taking advantage of a synthetic biology approach. This engineering-oriented discipline applies principles of modularity and standardization to redesign and interrogate endogenous biological systems. This review will elucidate how novel synthetic biology technologies constructed for eukaryotic systems can offer a promising toolkit for interfacing with calcium signaling and overcoming barriers in order to accelerate the process of Ca2+ detection optimization.
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Affiliation(s)
| | - Margaret S. Saha
- Department of Biology, College of William and Mary, Williamsburg, VA 23185, USA;
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7
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Inoshita T, Imai Y. Cytosolic and Mitochondrial Ca 2+ Imaging in Drosophila Dopaminergic Neurons. Methods Mol Biol 2021; 2322:207-214. [PMID: 34043206 DOI: 10.1007/978-1-0716-1495-2_20] [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: 06/12/2023]
Abstract
The ATP-producing organelle mitochondrion controls cellular or synaptic Ca2+ concentrations through temporal uptake of Ca2+ outside of the mitochondria. Although intracellular Ca2+ influx occurs during neuronal activity, a persistently higher concentration of intracellular Ca2+ is neurotoxic. Healthy mitochondria ensure rapid Ca2+ uptake, which is necessary for proper neuronal activity. Mitochondrial Ca2+ buffering activity decreases in aged or sick neurons. In this chapter, we will introduce our protocol for evaluating Ca2+ buffering activity through the mitochondria during neuronal activity of dopaminergic neurons.
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Affiliation(s)
- Tsuyoshi Inoshita
- Department of Neurodegenerative and Demented Disorders, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yuzuru Imai
- Department of Research for Parkinson's Disease, Juntendo University Graduate School of Medicine, Tokyo, Japan.
- Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan.
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8
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Aponte-Santiago NA, Littleton JT. Synaptic Properties and Plasticity Mechanisms of Invertebrate Tonic and Phasic Neurons. Front Physiol 2020; 11:611982. [PMID: 33391026 PMCID: PMC7772194 DOI: 10.3389/fphys.2020.611982] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/24/2020] [Indexed: 12/15/2022] Open
Abstract
Defining neuronal cell types and their associated biophysical and synaptic diversity has become an important goal in neuroscience as a mechanism to create comprehensive brain cell atlases in the post-genomic age. Beyond broad classification such as neurotransmitter expression, interneuron vs. pyramidal, sensory or motor, the field is still in the early stages of understanding closely related cell types. In both vertebrate and invertebrate nervous systems, one well-described distinction related to firing characteristics and synaptic release properties are tonic and phasic neuronal subtypes. In vertebrates, these classes were defined based on sustained firing responses during stimulation (tonic) vs. transient responses that rapidly adapt (phasic). In crustaceans, the distinction expanded to include synaptic release properties, with tonic motoneurons displaying sustained firing and weaker synapses that undergo short-term facilitation to maintain muscle contraction and posture. In contrast, phasic motoneurons with stronger synapses showed rapid depression and were recruited for short bursts during fast locomotion. Tonic and phasic motoneurons with similarities to those in crustaceans have been characterized in Drosophila, allowing the genetic toolkit associated with this model to be used for dissecting the unique properties and plasticity mechanisms for these neuronal subtypes. This review outlines general properties of invertebrate tonic and phasic motoneurons and highlights recent advances that characterize distinct synaptic and plasticity pathways associated with two closely related glutamatergic neuronal cell types that drive invertebrate locomotion.
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Affiliation(s)
- Nicole A. Aponte-Santiago
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, United States
| | - J. Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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The environmental toxicant ziram enhances neurotransmitter release and increases neuronal excitability via the EAG family of potassium channels. Neurobiol Dis 2020; 143:104977. [PMID: 32553709 DOI: 10.1016/j.nbd.2020.104977] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 06/11/2020] [Accepted: 06/13/2020] [Indexed: 12/21/2022] Open
Abstract
Environmental toxicants have the potential to contribute to the pathophysiology of multiple complex diseases, but the underlying mechanisms remain obscure. One such toxicant is the widely used fungicide ziram, a dithiocarbamate known to have neurotoxic effects and to increase the risk of Parkinson's disease. We have used Drosophila melanogaster as an unbiased discovery tool to identify novel molecular pathways by which ziram may disrupt neuronal function. Consistent with previous results in mammalian cells, we find that ziram increases the probability of synaptic vesicle release by dysregulation of the ubiquitin signaling system. In addition, we find that ziram increases neuronal excitability. Using a combination of live imaging and electrophysiology, we find that ziram increases excitability in both aminergic and glutamatergic neurons. This increased excitability is phenocopied and occluded by null mutant animals of the ether a-go-go (eag) potassium channel. A pharmacological inhibitor of the temperature sensitive hERG (human ether-a-go-go related gene) phenocopies the excitability effects of ziram but only at elevated temperatures. seizure (sei), a fly ortholog of hERG, is thus another candidate target of ziram. Taken together, the eag family of potassium channels emerges as a candidate for mediating some of the toxic effects of ziram. We propose that ziram may contribute to the risk of complex human diseases by blockade of human eag and sei orthologs, such as hERG.
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10
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A Cell-Based High-Throughput Screening Identified Two Compounds that Enhance PINK1-Parkin Signaling. iScience 2020; 23:101048. [PMID: 32335362 PMCID: PMC7183160 DOI: 10.1016/j.isci.2020.101048] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 03/14/2020] [Accepted: 04/04/2020] [Indexed: 12/21/2022] Open
Abstract
Early-onset Parkinson's disease-associated PINK1-Parkin signaling maintains mitochondrial health. Therapeutic approaches for enhancing PINK1-Parkin signaling present a potential strategy for treating various diseases caused by mitochondrial dysfunction. We report two chemical enhancers of PINK1-Parkin signaling, identified using a robust cell-based high-throughput screening system. These small molecules, T0466 and T0467, activate Parkin mitochondrial translocation in dopaminergic neurons and myoblasts at low doses that do not induce mitochondrial accumulation of PINK1. Moreover, both compounds reduce unfolded mitochondrial protein levels, presumably through enhanced PINK1-Parkin signaling. These molecules also mitigate the locomotion defect, reduced ATP production, and disturbed mitochondrial Ca2+ response in the muscles along with the mitochondrial aggregation in dopaminergic neurons through reduced PINK1 activity in Drosophila. Our results suggested that T0466 and T0467 may hold promise as therapeutic reagents in Parkinson's disease and related disorders.
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Werner J, Arian J, Bernhardt I, Ryglewski S, Duch C. Differential localization of voltage-gated potassium channels during Drosophila metamorphosis. J Neurogenet 2020; 34:133-150. [PMID: 31997675 DOI: 10.1080/01677063.2020.1715972] [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] [Indexed: 10/25/2022]
Abstract
Neuronal excitability is determined by the combination of different ion channels and their sub-neuronal localization. This study utilizes protein trap fly strains with endogenously tagged channels to analyze the spatial expression patterns of the four Shaker-related voltage-gated potassium channels, Kv1-4, in the larval, pupal, and adult Drosophila ventral nerve cord. We find that all four channels (Shaker, Kv1; Shab, Kv2; Shaw, Kv3; and Shal, Kv4) each show different spatial expression patterns in the Drosophila ventral nerve cord and are predominantly targeted to different sub-neuronal compartments. Shaker is abundantly expressed in axons, Shab also localizes to axons but mostly in commissures, Shaw expression is restricted to distinct parts of neuropils, and Shal is found somatodendritically, but also in axons of identified motoneurons. During early pupal life expression of all four Shaker-related channels is markedly decreased with an almost complete shutdown of expression at early pupal stage 5 (∼30% through metamorphosis). Re-expression of Kv1-4 channels at pupal stage 6 starts with abundant channel localization in neuronal somata, followed by channel targeting to the respective sub-neuronal compartments until late pupal life. The developmental time course of tagged Kv1-4 channel expression corresponds with previously published data on developmental changes in single neuron physiology, thus indicating that protein trap fly strains are a useful tool to analyze developmental regulation of potassium channel expression. Finally, we take advantage of the large diameter of the giant fiber (GF) interneuron to map channel expression onto the axon and axon terminals of an identified interneuron. Shaker, Shaw, and Shal but not Shab channels localize to the non-myelinated GF axonal membrane and axon terminals. This study constitutes a first step toward systematically analyzing sub-neuronal potassium channel localization in Drosophila. Functional implications as well as similarities and differences to Kv1-4 channel localization in mammalian neurons are discussed.
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Affiliation(s)
- Jan Werner
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Jashar Arian
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Ida Bernhardt
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Stefanie Ryglewski
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Carsten Duch
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
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12
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Calcium Imaging of Parvalbumin Neurons in the Dorsal Root Ganglia. eNeuro 2019; 6:ENEURO.0349-18.2019. [PMID: 31311802 PMCID: PMC6709205 DOI: 10.1523/eneuro.0349-18.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 06/12/2019] [Accepted: 06/22/2019] [Indexed: 01/06/2023] Open
Abstract
We investigated the calcium dynamics of dorsal root ganglion (DRG) neurons using transgenic mice to target expression of the genetically encoded calcium indicator (GECI), GCaMP6s, to a subset of neurons containing parvalbumin (PV), a calcium-binding protein present in proprioceptors and low-threshold mechanoreceptors. This study provides the first analysis of GECI calcium transient parameters from large-diameter DRG neurons. Our approach generated calcium transients of consistent shape and time-course, with quantifiable characteristics. Four parameters of calcium transients were determined to vary independently from each other and thus are likely influenced by different calcium-regulating mechanisms: peak amplitude, rise time (RT), decay time, and recovery time. Pooled analysis of 188 neurons demonstrated unimodal distributions, providing evidence that PV+ DRG neurons regulate calcium similarly as a population despite their differences in size, electrical properties, and functional sensitivities. Calcium transients increased in size with elevated extracellular calcium, longer trains of action potentials, and higher stimulation frequencies. RT and decay time increased with the addition of the selective sarco/endoplasmic reticulum calcium ATPases (SERCA) blocker, thapsigargin (TG), while peak amplitude and recovery time remained the same. When elevating bath pH to 8.8 to block plasma-membrane calcium ATPases (PMCA), all measured parameters significantly increased. These results illustrate that GECI calcium transients provide sufficient resolution to detect changes in electrical activity and intracellular calcium concentration, as well as discern information about the activity of specific subclasses of calcium regulatory mechanisms.
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13
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Li P, Geng X, Jiang H, Caccavano A, Vicini S, Wu JY. Measuring Sharp Waves and Oscillatory Population Activity With the Genetically Encoded Calcium Indicator GCaMP6f. Front Cell Neurosci 2019; 13:274. [PMID: 31275115 PMCID: PMC6593119 DOI: 10.3389/fncel.2019.00274] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 06/05/2019] [Indexed: 12/16/2022] Open
Abstract
GCaMP6f is among the most widely used genetically encoded calcium indicators for monitoring neuronal activity. Applications are at both the cellular and population levels. Here, we explore two important and under-explored issues. First, we have tested if GCaMP6f is sensitive enough for the detection of population activity with sparse firing, similar to the sensitivity of the local field potential (LFP). Second, we have tested if GCaMP6f is fast enough for the detection of fast network oscillations critical for the encoding and consolidation of memory. We have focused this study on the activity of the hippocampal network including sharp waves (SWs), carbachol-induced theta oscillations, and interictal-like spikes. We compare simultaneous LFP and optical GCaMP6f fluorescent recordings in Thy1-GCaMP6f mouse hippocampal slices. We observe that SWs produce a clear population GCaMP6f signal above noise with an average magnitude of 0.3% ΔF/F. This population signal is highly correlated with the LFP, albeit with a delay of 40.3 ms (SD 10.8 ms). The population GCaMP6f signal follows the LFP evoked by 20 Hz stimulation with high fidelity, while electrically evoked oscillations up to 40 Hz were detectable with reduced amplitude. GCaMP6f and LFP signals showed a large amplitude discrepancy. The amplitude of GCaMP6f fluorescence increased by a factor of 28.9 (SD 13.5) between spontaneous SWs and carbachol-induced theta bursts, while the LFP amplitude increased by a factor of 2.4 (SD 1.0). Our results suggest that GCaMP6f is a useful tool for applications commonly considered beyond the scope of genetically encoded calcium indicators. In particular, population GCaMP6f signals are sensitive enough for detecting synchronous network events with sparse firing and sub-threshold activity, as well as asynchronous events with only a nominal LFP. In addition, population GCaMP6f signals are fast enough for monitoring theta and beta oscillations (<25 Hz). Faster calcium indicators (e.g., GCaMP7) will further improve the frequency response for the detection of gamma band oscillations. The advantage of population optical over LFP recordings are that they are non-contact and free from stimulation artifacts. These features may be particularly useful for high-throughput recordings and applications sensitive to stimulus artifact, such as monitoring responses during continuous stimulation.
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Affiliation(s)
- Pinggan Li
- Department of Pediatric Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Department of Neuroscience, Georgetown University, Washington, DC, United States
| | - Xinling Geng
- Department of Neuroscience, Georgetown University, Washington, DC, United States
- School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Huiyi Jiang
- Department of Neuroscience, Georgetown University, Washington, DC, United States
- Department of Pediatrics, The First Hospital of Jilin University, Changchun, China
| | - Adam Caccavano
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, United States
| | - Stefano Vicini
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, United States
| | - Jian-young Wu
- Department of Neuroscience, Georgetown University, Washington, DC, United States
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Abstract
The Drosophila melanogaster larval neuromuscular system is extensively used by researchers to study neuronal cell biology, and Drosophila glutamatergic motor neurons have become a major model system. There are two main Types of glutamatergic motor neurons, Ib and Is, with different structural and physiological properties at synaptic level at the neuromuscular junction. To generate genetic tools to identify and manipulate motor neurons of each Type, we screened for GAL4 driver lines for this purpose. Here we describe GAL4 drivers specific for examples of neurons within each Type, Ib or Is. These drivers showed high expression levels and were expressed in only few motor neurons, making them amenable tools for specific studies of both axonal and synapse biology in identified Type I motor neurons.
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15
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Xing X, Wu CF. Inter-relationships among physical dimensions, distal-proximal rank orders, and basal GCaMP fluorescence levels in Ca 2+ imaging of functionally distinct synaptic boutons at Drosophila neuromuscular junctions. J Neurogenet 2018; 32:195-208. [PMID: 30322321 DOI: 10.1080/01677063.2018.1504043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
GCaMP imaging is widely employed for investigating neuronal Ca2+ dynamics. The Drosophila larval neuromuscular junction (NMJ) consists of three distinct types of motor terminals (type Ib, Is and II). We investigated whether variability in synaptic bouton sizes and GCaMP expression levels confound interpretations of GCaMP readouts, in inferring the intrinsic Ca2+ handling properties among these functionally distinct synapses. Analysis of large data sets accumulated over years established the wide ranges of bouton sizes and GCaMP baseline fluorescence, with large overlaps among synaptic categories. We showed that bouton size and GCaMP baseline fluorescence were not confounding factors in determining the characteristic frequency responses among type Ib, Is and II synapses. More importantly, the drastic phenotypes that hyperexcitability mutations manifest preferentially in particular synaptic categories, were not obscured by bouton heterogeneity in physical size and GCaMP expression level. Our data enabled an extensive analysis of the distal-proximal gradient of GCaMP responses upon genetic and pharmacological manipulations. The results illustrate the conditions that disrupt or enhance the distal-proximal gradients. For example, stimulus frequencies just above the threshold level produced the steepest gradient in low Ca2+ (0.1 mM) saline, while supra-threshold stimulation flattened the gradient. Moreover, membrane hyperexcitability mutations (eag1 Sh120 and parabss1) and mitochondrial inhibition by dinitrophenol (DNP) disrupted the gradient. However, a novel distal-proximal gradient of decay kinetics appeared after long-term DNP incubation. We performed focal recording to assess the failure rates in transmission at low Ca2+ levels, which yielded indications of a mild distal-proximal gradient in release probability.
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Affiliation(s)
- Xiaomin Xing
- a Department of Biology , University of Iowa , Iowa City , IA , USA
| | - Chun-Fang Wu
- a Department of Biology , University of Iowa , Iowa City , IA , USA
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16
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Abstract
While readers of Journal of Neurogenetics may be familiar with Harold Atwood's work with Drosophila, most may know little of his previous work on crustacean neuromuscular systems that prepared him to utilise Drosophila neuromuscular junctions. Here, I will give brief overviews of his academic career, one line of his research that persisted throughout his career and his entry to the Drosophila field. This is not a review paper. Finally, I will relate my experiences with Atwood since 1967 as an undergraduate, Postdoctoral Fellow, and Faculty member and finish with some personal anecdotal observations.
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Affiliation(s)
- Milton P Charlton
- a Physiology Department , University of Toronto , Toronto , Ontario , Canada
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17
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Machamer JB, Woolums BM, Fuller GG, Lloyd TE. FUS causes synaptic hyperexcitability in Drosophila dendritic arborization neurons. Brain Res 2018; 1693:55-66. [PMID: 29625118 PMCID: PMC6347466 DOI: 10.1016/j.brainres.2018.03.037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 03/25/2018] [Accepted: 03/31/2018] [Indexed: 12/13/2022]
Abstract
Mutations in the nuclear localization signal of the RNA binding protein FUS cause both Frontotemporal Dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS). These mutations result in a loss of FUS from the nucleus and the formation of FUS-containing cytoplasmic aggregates in patients. To better understand the role of cytoplasmic FUS mislocalization in the pathogenesis of ALS, we identified a population of cholinergic neurons in Drosophila that recapitulate these pathologic hallmarks. Expression of mutant FUS or the Drosophila homolog, Cabeza (Caz), in class IV dendritic arborization neurons results in cytoplasmic mislocalization and axonal transport to presynaptic terminals. Interestingly, overexpression of FUS or Caz causes the progressive loss of neuronal projections, reduction of synaptic mitochondria, and the appearance of large calcium transients within the synapse. Additionally, we find that overexpression of mutant but not wild type FUS results in a reduction in presynaptic Synaptotagmin, an integral component of the neurotransmitter release machinery, and mutant Caz specifically disrupts axonal transport and induces hyperexcitability. These results suggest that FUS/Caz overexpression disrupts neuronal function through multiple mechanisms, and that ALS-causing mutations impair the transport of synaptic vesicle proteins and induce hyperexcitability.
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Affiliation(s)
- James B Machamer
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Brian M Woolums
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Gregory G Fuller
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Thomas E Lloyd
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States.
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18
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Singh M, Lujan B, Renden R. Presynaptic GCaMP expression decreases vesicle release probability at the calyx of Held. Synapse 2018; 72:e22040. [PMID: 29935099 PMCID: PMC6186185 DOI: 10.1002/syn.22040] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/04/2018] [Accepted: 06/05/2018] [Indexed: 12/15/2022]
Abstract
Synaptic vesicle (SV) exocytosis is intimately dependent on free local Ca2+ near active zones. Genetically encoded calcium indicators (GECIs) have become an indispensable tool to monitor calcium dynamics during physiological responses, and they are widely used as a proxy to monitor activity in neuronal ensembles and at synaptic terminals. However, GECIs’ ability to bind Ca2+ at physiologically relevant concentration makes them strong candidates to affect calcium homeostasis and alter synaptic transmission by exogenously increasing Ca2+ buffering. In the present study, we show that genetically expressed GCaMP6m modulates SV release probability at the mouse calyx of Held synapse. GCaMP6m expression for approximately three weeks decreased initial SV release for both low‐frequency stimulation and high‐frequency stimulation trains, and slowed presynaptic short‐term depression. However, GCaMP6m does not affect quantal events during spontaneous activity at this synapse. This study emphasizes the careful use of GECIs as monitors of neuronal activity and inspects the role of these transgenic indicators which may alter calcium‐dependent physiological responses.
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Affiliation(s)
- Mahendra Singh
- Department of Physiology and Cell Biology, University of Nevada, Reno, Nevada, 89557
| | - Brendan Lujan
- Department of Physiology and Cell Biology, University of Nevada, Reno, Nevada, 89557.,Currently at Vollum Institute, Oregon Health and Science University, Portland, Oregon
| | - Robert Renden
- Department of Physiology and Cell Biology, University of Nevada, Reno, Nevada, 89557
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