1
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Jiang X, Shi J, Yang H, Zhao Z. The cholinergic pathway transmits signals of neuropeptide F to regulate feeding of Ostrinia furnacalis larvae. PEST MANAGEMENT SCIENCE 2023; 79:3593-3601. [PMID: 37183359 DOI: 10.1002/ps.7544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/02/2023] [Accepted: 05/08/2023] [Indexed: 05/16/2023]
Abstract
BACKGROUND Feeding is the basis of animal survival and reproduction. In insects, the neuropeptide F (NPF), a homologous polypeptide of NPY in vertebrates, plays an important role in regulation of feeding behavior. However, relatively little has been known about the molecular mechanism of feeding. RESULTS In this study, we show that the cholinergic pathway is very important in signaling transmission of NPF feeding regulation in Ostrinia furnacalis larvae, in which the choline acetyltransferase (ChAT), the vesicular acetylcholine transporter (vAChT) in presynaptic membrane and the nicotinic acetylcholine receptor (nAChR) in postsynaptic membrane are positively regulated by NPF, while the ace1 and ace2 encoding the acetylcholinesterase (AChE) are negatively regulated by NPF, leading to a balance of acetylcholine (ACh)-the excitatory transmitter. More, the cholinergic pathway further transmits signaling to the downstream pathways of the phosphoInositide-3 kinase (PI3K) and the cAMP responsive element binding protein (CREB), respectively. CONCLUSION The cholinergic transmission, positively regulated by NPF, is involved in feeding of O. furnacalis larvae via downstream PI3K and the CREB pathways, respectively. The deexcitation of cell cholinergic pathway or inhibition of PI3K and CREB lead to decreases of larval feeding amount. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Xuemin Jiang
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Jian Shi
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Haoran Yang
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Zhangwu Zhao
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
- College of Life Science, Institute of Life Science and Green Development, Hebei University, Baoding, China
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2
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Harrington S, Pyche J, Burns AR, Spalholz T, Ryan KT, Baker RJ, Ching J, Rufener L, Lautens M, Kulke D, Vernudachi A, Zamanian M, Deuther-Conrad W, Brust P, Roy PJ. Nemacol is a small molecule inhibitor of C. elegans vesicular acetylcholine transporter with anthelmintic potential. Nat Commun 2023; 14:1816. [PMID: 37002199 PMCID: PMC10066365 DOI: 10.1038/s41467-023-37452-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 03/17/2023] [Indexed: 04/03/2023] Open
Abstract
Nematode parasites of humans and livestock pose a significant burden to human health, economic development, and food security. Anthelmintic drug resistance is widespread among parasites of livestock and many nematode parasites of humans lack effective treatments. Here, we present a nitrophenyl-piperazine scaffold that induces motor defects rapidly in the model nematode Caenorhabditis elegans. We call this scaffold Nemacol and show that it inhibits the vesicular acetylcholine transporter (VAChT), a target recognized by commercial animal and crop health groups as a viable anthelmintic target. We demonstrate that it is possible to create Nemacol analogs that maintain potent in vivo activity whilst lowering their affinity to the mammalian VAChT 10-fold. We also show that Nemacol enhances the ability of the anthelmintic Ivermectin to paralyze C. elegans and the ruminant nematode parasite Haemonchus contortus. Hence, Nemacol represents a promising new anthelmintic scaffold that acts through a validated anthelmintic target.
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Affiliation(s)
- Sean Harrington
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, M5S 1A8, Canada
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Jacob Pyche
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, M5S 1A8, Canada
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
| | - Andrew R Burns
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Tina Spalholz
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, 04318, Leipzig, Germany
| | - Kaetlyn T Ryan
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Rachel J Baker
- The Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, M5S 3H6, Canada
| | - Justin Ching
- The Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, M5S 3H6, Canada
| | - Lucien Rufener
- INVENesis Sàrl, Route de Neuchâtel 15A, 2072, St Blaise (NE), Switzerland
| | - Mark Lautens
- The Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, M5S 3H6, Canada
| | - Daniel Kulke
- Research Parasiticides, Bayer Animal Health GmbH, Monheim, Germany
- Department of Biomedical Sciences, Iowa State University, Ames, IA, 50011, USA
- Global Innovation, Boehringer Ingelheim Vetmedica GmbH, Binger Str. 173, 55218, Ingelheim am Rhein, Germany
| | | | - Mostafa Zamanian
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Winnie Deuther-Conrad
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, 04318, Leipzig, Germany
| | - Peter Brust
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, 04318, Leipzig, Germany
- The Lübeck Institute of Experimental Dermatology, University Medical Center Schleswig-Holstein, 23562, Lübeck, Germany
| | - Peter J Roy
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, M5S 1A8, Canada.
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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3
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Almazán A, Çevrim Ç, Musser JM, Averof M, Paris M. Crustacean leg regeneration restores complex microanatomy and cell diversity. SCIENCE ADVANCES 2022; 8:eabn9823. [PMID: 36001670 PMCID: PMC9401613 DOI: 10.1126/sciadv.abn9823] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
Animals can regenerate complex organs, yet this process frequently results in imprecise replicas of the original structure. In the crustacean Parhyale, embryonic and regenerating legs differ in gene expression dynamics but produce apparently similar mature structures. We examine the fidelity of Parhyale leg regeneration using complementary approaches to investigate microanatomy, sensory function, cellular composition, and cell molecular profiles. We find that regeneration precisely replicates the complex microanatomy and spatial distribution of external sensory organs and restores their sensory function. Single-nuclei sequencing shows that regenerated and uninjured legs are indistinguishable in terms of cell-type composition and transcriptional profiles. This remarkable fidelity highlights the ability of organisms to achieve identical outcomes via distinct processes.
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Affiliation(s)
- Alba Almazán
- Institut de Génomique Fonctionnelle de Lyon (IGFL), Centre National de la Recherche Scientifique (CNRS), École Normale Supérieure de Lyon and Université Claude Bernard Lyon 1, 69007 Lyon, France
| | - Çağrı Çevrim
- Institut de Génomique Fonctionnelle de Lyon (IGFL), Centre National de la Recherche Scientifique (CNRS), École Normale Supérieure de Lyon and Université Claude Bernard Lyon 1, 69007 Lyon, France
| | - Jacob M. Musser
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, Heidelberg 69117, Germany
| | - Michalis Averof
- Institut de Génomique Fonctionnelle de Lyon (IGFL), Centre National de la Recherche Scientifique (CNRS), École Normale Supérieure de Lyon and Université Claude Bernard Lyon 1, 69007 Lyon, France
| | - Mathilde Paris
- Institut de Génomique Fonctionnelle de Lyon (IGFL), Centre National de la Recherche Scientifique (CNRS), École Normale Supérieure de Lyon and Université Claude Bernard Lyon 1, 69007 Lyon, France
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4
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Hamid R, Sant HS, Kulkarni MN. Choline Transporter regulates olfactory habituation via a neuronal triad of excitatory, inhibitory and mushroom body neurons. PLoS Genet 2021; 17:e1009938. [PMID: 34914708 PMCID: PMC8675691 DOI: 10.1371/journal.pgen.1009938] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 11/08/2021] [Indexed: 11/18/2022] Open
Abstract
Choline is an essential component of Acetylcholine (ACh) biosynthesis pathway which requires high-affinity Choline transporter (ChT) for its uptake into the presynaptic terminals of cholinergic neurons. Previously, we had reported a predominant expression of ChT in memory processing and storing region of the Drosophila brain called mushroom bodies (MBs). It is unknown how ChT contributes to the functional principles of MB operation. Here, we demonstrate the role of ChT in Habituation, a non-associative form of learning. Odour driven habituation traces are laid down in ChT dependent manner in antennal lobes (AL), projection neurons (PNs), and MBs. We observed that reduced habituation due to knock-down of ChT in MBs causes hypersensitivity towards odour, suggesting that ChT also regulates incoming stimulus suppression. Importantly, we show for the first time that ChT is not unique to cholinergic neurons but is also required in inhibitory GABAergic neurons to drive habituation behaviour. Our results support a model in which ChT regulates both habituation and incoming stimuli through multiple circuit loci via an interplay between excitatory and inhibitory neurons. Strikingly, the lack of ChT in MBs shows characteristics similar to the major reported features of Autism spectrum disorders (ASD), including attenuated habituation, sensory hypersensitivity as well as defective GABAergic signalling. Our data establish the role of ChT in habituation and suggest that its dysfunction may contribute to neuropsychiatric disorders like ASD.
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Affiliation(s)
- Runa Hamid
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research (CSIR-CCMB), Hyderabad, India
| | - Hitesh Sonaram Sant
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research (CSIR-CCMB), Hyderabad, India
| | - Mrunal Nagaraj Kulkarni
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research (CSIR-CCMB), Hyderabad, India
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5
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Eadaim A, Hahm ET, Justice ED, Tsunoda S. Cholinergic Synaptic Homeostasis Is Tuned by an NFAT-Mediated α7 nAChR-K v4/Shal Coupled Regulatory System. Cell Rep 2021; 32:108119. [PMID: 32905767 PMCID: PMC7521586 DOI: 10.1016/j.celrep.2020.108119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/23/2020] [Accepted: 08/17/2020] [Indexed: 11/26/2022] Open
Abstract
Homeostatic synaptic plasticity (HSP) involves compensatory mechanisms employed by neurons and circuits to preserve signaling when confronted with global changes in activity that may occur during physiological and pathological conditions. Cholinergic neurons, which are especially affected in some pathologies, have recently been shown to exhibit HSP mediated by nicotinic acetylcholine receptors (nAChRs). In Drosophila central neurons, pharmacological blockade of activity induces a homeostatic response mediated by the Drosophila α7 (Dα7) nAChR, which is tuned by a subsequent increase in expression of the voltage-dependent Kv4/Shal channel. Here, we show that an in vivo reduction of cholinergic signaling induces HSP mediated by Dα7 nAChRs, and this upregulation of Dα7 itself is sufficient to trigger transcriptional activation, mediated by nuclear factor of activated T cells (NFAT), of the Kv4/Shal gene, revealing a receptor-ion channel system coupled for homeostatic tuning in cholinergic neurons. Eadaim et al. show that in vivo reduction of cholinergic signaling in Drosophila neurons induces synaptic homeostasis mediated by Dα7 nAChRs. This upregulation of Dα7 induces Kv4/Shal gene expression mediated by nuclear factor of activated T cells (NFAT), revealing a receptor-ion channel system coupled for homeostatic tuning in cholinergic neurons.
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Affiliation(s)
- Abdunaser Eadaim
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Eu-Teum Hahm
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Elizabeth D Justice
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Susan Tsunoda
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
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6
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Duerr JS, McManus JR, Crowell JA, Rand JB. Analysis of C. elegans acetylcholine synthesis mutants reveals a temperature-sensitive requirement for cholinergic neuromuscular function. Genetics 2021; 218:6283614. [PMID: 34028515 DOI: 10.1093/genetics/iyab078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/04/2021] [Indexed: 11/13/2022] Open
Abstract
In Caenorhabditis elegans, the cha-1 gene encodes choline acetyltransferase (ChAT), the enzyme that synthesizes the neurotransmitter acetylcholine. We have analyzed a large number of cha-1 hypomorphic mutants, most of which are missense alleles. Some homozygous cha-1 mutants have approximately normal ChAT immunoreactivity; many other alleles lead to consistent reductions in synaptic immunostaining, although the residual protein appears to be stable. Regardless of protein levels, neuromuscular function of almost all mutants is temperature sensitive, i.e., neuromuscular function is worse at 25° than at 14°. We show that the temperature effects are not related to acetylcholine release, but specifically to alterations in acetylcholine synthesis. This is not a temperature-dependent developmental phenotype, because animals raised at 20° to young adulthood and then shifted for 2 hours to either 14° or 25° had swimming and pharyngeal pumping rates similar to animals grown and assayed at either 14° or 25°, respectively. We also show that the temperature-sensitive phenotypes are not limited to missense alleles; rather, they are a property of most or all severe cha-1 hypomorphs. We suggest that our data are consistent with a model of ChAT protein physically, but not covalently, associated with synaptic vesicles; and there is a temperature-dependent equilibrium between vesicle-associated and cytoplasmic (i.e., soluble) ChAT. Presumably, in severe cha-1 hypomorphs, increasing the temperature would promote dissociation of some of the mutant ChAT protein from synaptic vesicles, thus removing the site of acetylcholine synthesis (ChAT) from the site of vesicular acetylcholine transport. This, in turn, would decrease the rate and extent of vesicle-filling, thus increasing the severity of the behavioral deficits.
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Affiliation(s)
- Janet S Duerr
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.,Department of Biological Sciences, Ohio University, Athens, Ohio 45701, USA
| | - John R McManus
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - John A Crowell
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - James B Rand
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.,Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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7
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Vesicular neurotransmitter transporters in Drosophila melanogaster. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183308. [PMID: 32305263 DOI: 10.1016/j.bbamem.2020.183308] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/09/2020] [Accepted: 04/10/2020] [Indexed: 12/11/2022]
Abstract
Drosophila melanogaster express vesicular transporters for the storage of neurotransmitters acetylcholine, biogenic amines, GABA, and glutamate. The large array of powerful molecular-genetic tools available in Drosophila enhances the use of this model organism for studying transporter function and regulation.
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8
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White D, de Sousa Abreu RP, Blake A, Murphy J, Showell S, Kitamoto T, Lawal HO. Deficits in the vesicular acetylcholine transporter alter lifespan and behavior in adult Drosophila melanogaster. Neurochem Int 2020; 137:104744. [PMID: 32315665 DOI: 10.1016/j.neuint.2020.104744] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 04/06/2020] [Accepted: 04/09/2020] [Indexed: 10/24/2022]
Abstract
The neurotransmitter acetylcholine (ACh) is involved in critical organismal functions that include locomotion and cognition. Importantly, alterations in the cholinergic system are a key underlying factor in cognitive defects associated with aging. One essential component of cholinergic synaptic transmission is the vesicular ACh transporter (VAChT), which regulates the packaging of ACh into synaptic vesicles for extracellular release. Mutations that cause a reduction in either protein level or activity lead to diminished locomotion ability whereas complete loss of function of VAChT is lethal. While much is known about the function of VAChT, the direct role of altered ACh release and its association with either an impairment or an enhancement of cognitive function are still not fully understood. We hypothesize that point mutations in Vacht cause age-related deficits in cholinergic-mediated behaviors such as locomotion, and learning and memory. Using Drosophila melanogaster as a model system, we have studied several mutations within Vacht and observed their effect on survivability and locomotive behavior. Here we report for the first time a weak hypomorphic Vacht allele that shows a differential effect on ACh-linked behaviors. We also demonstrate that partially rescued Vacht point mutations cause an allele-dependent deficit in lifespan and defects in locomotion ability. Moreover, using a thorough data analytics strategy to identify exploratory behavioral patterns, we introduce new paradigms for measuring locomotion-related activities that could not be revealed or detected by a simple measure of the average speed alone. Together, our data indicate a role for VAChT in the maintenance of longevity and locomotion abilities in Drosophila and we provide additional measurements of locomotion that can be useful in determining subtle changes in Vacht function on locomotion-related behaviors.
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Affiliation(s)
- Daniel White
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, 19901, USA
| | - Raquel P de Sousa Abreu
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA
| | - Andrew Blake
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, 19901, USA
| | - Jeremy Murphy
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, 19901, USA
| | - Shardae Showell
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, 19901, USA
| | - Toshihiro Kitamoto
- Department of Anesthesia, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Hakeem O Lawal
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, 19901, USA.
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9
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Overexpression of the vesicular acetylcholine transporter disrupts cognitive performance and causes age-dependent locomotion decline in Drosophila. Mol Cell Neurosci 2020; 105:103483. [PMID: 32217162 DOI: 10.1016/j.mcn.2020.103483] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 03/14/2020] [Accepted: 03/22/2020] [Indexed: 12/11/2022] Open
Abstract
Acetylcholinergic (ACh) neurotransmission is essential for key organismal functions such as locomotion and cognition. However, the mechanism through which ACh is regulated in the central nervous system is not fully understood. The vesicular acetylcholine transporter (VAChT) mediates the packaging and transport of ACh for exocytotic release and is a critical component of the ACh release machinery. Yet its precise role in the maintenance of cholinergic tone remains a subject of active investigation. Here we use the overexpression of VAChT as a tool to investigate the role of changes in ACh exocytosis on the regulation of synaptic activity and its downstream consequences. We measured the effect of an increase in VAChT expression on locomotion and cognitive performance as well as on organismal survival across the lifespan. We report the surprising finding that increased VAChT expression results in a significantly shorter lifespan in comparison to control flies. Moreover, constructs overexpressing VAChT demonstrate an age-dependent decrease in locomotion performance. Importantly, we report clear deficits in learning and memory which we measured through a courtship conditioning assay. Together, these data provide evidence for the adverse effects of overexpression of the vesicular acetylcholine transporter in the maintenance of normal behavioral abilities in Drosophila and demonstrates for the first time a role for ACh in the regulation of organismal survival.
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10
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Hamid R, Hajirnis N, Kushwaha S, Saleem S, Kumar V, Mishra RK. Drosophila Choline transporter non-canonically regulates pupal eclosion and NMJ integrity through a neuronal subset of mushroom body. Dev Biol 2019; 446:80-93. [DOI: 10.1016/j.ydbio.2018.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/25/2018] [Accepted: 12/07/2018] [Indexed: 12/19/2022]
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11
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Vernon SW, Goodchild J, Baines RA. The VAChTY49N mutation provides insecticide-resistance but perturbs evoked cholinergic neurotransmission in Drosophila. PLoS One 2018; 13:e0203852. [PMID: 30204788 PMCID: PMC6133381 DOI: 10.1371/journal.pone.0203852] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 08/28/2018] [Indexed: 12/05/2022] Open
Abstract
Global agriculture and the control of insect disease vectors have developed with a heavy reliance on insecticides. The increasing incidence of resistance, for virtually all insecticides, threatens both food supply and effective control of insect borne disease. CASPP ((5-chloro-1’-[(E)-3-(4-chlorophenyl)allyl]spiro[indoline-3,4’-piperidine]-1-yl}-(2-chloro-4-pyridyl)methanone)) compounds are a potential new class of neuroactive insecticide specifically targeting the Vesicular Acetylcholine Transporter (VAChT). Resistance to CASPP, under laboratory conditions, has been reported following either up-regulation of wildtype VAChT expression or the presence of a specific point mutation (VAChTY49N). However, the underlying mechanism of CASPP-resistance, together with the consequence to insect viability of achieving resistance, is unknown. In this study, we use electrophysiological characterisation of cholinergic release at Drosophila larval interneuron→motoneuron synapses to investigate the physiological implications of these two identified modes of CASPP resistance. We show that both VAChT up-regulation or the expression of VAChTY49N increases miniature (mini) release frequency. Mini frequency appears deterministic of CASPP activity. However, maintenance of SV release is not indicative of resistance in all cases. This is evidenced through expression of syntaxin or complexin mutants (sytx3-61/cpxSH1) that show similarly high mini release frequency but are not resistant to CASPP. The VAChTY49N mutation additionally disrupts action potential-evoked cholinergic release and fictive locomotor patterning through depletion of releasable synaptic vesicles. This observation suggests a functional trade-off for this point mutation, which is not seen when wildtype VAChT is up-regulated.
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Affiliation(s)
- Samuel W. Vernon
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Jim Goodchild
- Syngenta Crop Protection Research, Bracknell, Berkshire, United Kingdom
| | - Richard A. Baines
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
- * E-mail:
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12
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Graziadio L, Palumbo V, Cipressa F, Williams BC, Cenci G, Gatti M, Goldberg ML, Bonaccorsi S. Phenotypic characterization of diamond (dind), a Drosophila gene required for multiple aspects of cell division. Chromosoma 2018; 127:489-504. [PMID: 30120539 DOI: 10.1007/s00412-018-0680-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 01/04/2023]
Abstract
Many genes are required for the assembly of the mitotic apparatus and for proper chromosome behavior during mitosis and meiosis. A fruitful approach to elucidate the mechanisms underlying cell division is the accurate phenotypic characterization of mutations in these genes. Here, we report the identification and characterization of diamond (dind), an essential Drosophila gene required both for mitosis of larval brain cells and for male meiosis. Larvae homozygous for any of the five EMS-induced mutations die in the third-instar stage and exhibit multiple mitotic defects. Mutant brain cells exhibit poorly condensed chromosomes and frequent chromosome breaks and rearrangements; they also show centriole fragmentation, disorganized mitotic spindles, defective chromosome segregation, endoreduplicated metaphases, and hyperploid and polyploid cells. Comparable phenotypes occur in mutant spermatogonia and spermatocytes. The dind gene encodes a non-conserved protein with no known functional motifs. Although the Dind protein exhibits a rather diffuse localization in both interphase and mitotic cells, fractionation experiments indicate that some Dind is tightly associated with the chromatin. Collectively, these results suggest that loss of Dind affects chromatin organization leading to defects in chromosome condensation and integrity, which in turn affect centriole stability and spindle assembly. However, our results do not exclude the possibility that Dind directly affects some behaviors of the spindle and centrosomes.
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Affiliation(s)
- Lucia Graziadio
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy
| | - Valeria Palumbo
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy
| | - Francesca Cipressa
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy.,Museo storico della fisica e centro di studi e ricerche Enrico Fermi, Rome, Italy
| | - Byron C Williams
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Giovanni Cenci
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy.,Istituto Pasteur Fondazione Cenci Bolognetti, Rome, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy.,Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Rome, Italy
| | - Michael L Goldberg
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
| | - Silvia Bonaccorsi
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy.
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13
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Immunolocalization of the vesicular acetylcholine transporter in larval and adult Drosophila neurons. Neurosci Lett 2017; 643:76-83. [PMID: 28188850 DOI: 10.1016/j.neulet.2017.02.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 01/20/2017] [Accepted: 02/06/2017] [Indexed: 11/21/2022]
Abstract
Vesicular acetylcholine transporter (VAChT) function is essential for organismal survival, mediating the packaging of acetylcholine (ACh) for exocytotic release. However, its expression pattern in the Drosophila brain has not been fully elucidated. To investigate the localization of VAChT, we developed an antibody against the C terminal region of the protein and we show that this antibody recognizes a 65KDa protein corresponding to VAChT on an immunoblot in both Drosophila head homogenates and in Schneider 2 cells. Further, we report for the first time the expression of VAChT in the antennal lobe and ventral nerve cord of Drosophila larva; and we independently confirm the expression of the protein in mushroom bodies and optic lobes of adult Drosophila. Importantly, we show that VAChT co-localizes with a synaptic vesicle marker in vivo, confirming previous reports of the localization of VAChT to synaptic terminals. Together, these findings help establish the vesicular localization of VAChT in cholinergic neurons in Drosophila and present an important molecular tool with which to dissect the function of the transporter in vivo.
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Drosophila melanogaster as a genetic model system to study neurotransmitter transporters. Neurochem Int 2014; 73:71-88. [PMID: 24704795 DOI: 10.1016/j.neuint.2014.03.015] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 03/20/2014] [Accepted: 03/24/2014] [Indexed: 12/30/2022]
Abstract
The model genetic organism Drosophila melanogaster, commonly known as the fruit fly, uses many of the same neurotransmitters as mammals and very similar mechanisms of neurotransmitter storage, release and recycling. This system offers a variety of powerful molecular-genetic methods for the study of transporters, many of which would be difficult in mammalian models. We review here progress made using Drosophila to understand the function and regulation of neurotransmitter transporters and discuss future directions for its use.
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Yi W, Zhang Y, Tian Y, Guo J, Li Y, Guo A. A subset of cholinergic mushroom body neurons requires Go signaling to regulate sleep in Drosophila. Sleep 2013; 36:1809-21. [PMID: 24293755 DOI: 10.5665/sleep.3206] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
STUDY OBJECTIVES Identifying the neurochemistry and neural circuitry of sleep regulation is critical for understanding sleep and various sleep disorders. Fruit flies display sleep-like behavior, sharing essential features with sleep of vertebrate. In the fruit fly's central brain, the mushroom body (MB) has been highlighted as a sleep center; however, its neurochemical nature remains unclear, and whether it promotes sleep or wake is still a topic of controversy. DESIGN We used a video recording system to accurately monitor the locomotor activity and sleep status. Gene expression was temporally and regionally manipulated by heat induction and the Gal4/UAS system. MEASUREMENTS AND RESULTS We found that expressing pertussis toxin (PTX) in the MB by c309-Gal4 to block Go activity led to unique sleep defects as dramatic sleep increase in daytime and fragmented sleep in nighttime. We narrowed down the c309-Gal4 expressing brain regions to the MB α/β core neurons that are responsible for the Go-mediated sleep effects. Using genetic tools of neurotransmitter-specific Gal80 and RNA interference approach to suppress acetylcholine signal, we demonstrated that these MB α/β core neurons were cholinergic and sleep-promoting neurons, supporting that Go mediates an inhibitory signal. Interestingly, we found that adjacent MB α/β neurons were also cholinergic but wake-promoting neurons, in which Go signal was also required. CONCLUSION Our findings in fruit flies characterized a group of sleep-promoting neurons surrounded by a group of wake-promoting neurons. The two groups of neurons are both cholinergic and use Go inhibitory signal to regulate sleep.
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Affiliation(s)
- Wei Yi
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China ; University of Chinese Academy of Sciences, Beijing, China
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SMN is required for sensory-motor circuit function in Drosophila. Cell 2012; 151:427-39. [PMID: 23063130 DOI: 10.1016/j.cell.2012.09.011] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 06/15/2012] [Accepted: 09/10/2012] [Indexed: 11/23/2022]
Abstract
Spinal muscular atrophy (SMA) is a lethal human disease characterized by motor neuron dysfunction and muscle deterioration due to depletion of the ubiquitous survival motor neuron (SMN) protein. Drosophila SMN mutants have reduced muscle size and defective locomotion, motor rhythm, and motor neuron neurotransmission. Unexpectedly, restoration of SMN in either muscles or motor neurons did not alter these phenotypes. Instead, SMN must be expressed in proprioceptive neurons and interneurons in the motor circuit to nonautonomously correct defects in motor neurons and muscles. SMN depletion disrupts the motor system subsequent to circuit development and can be mimicked by the inhibition of motor network function. Furthermore, increasing motor circuit excitability by genetic or pharmacological inhibition of K(+) channels can correct SMN-dependent phenotypes. These results establish sensory-motor circuit dysfunction as the origin of motor system deficits in this SMA model and suggest that enhancement of motor neural network activity could ameliorate the disease.
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The vesicular acetylcholine transporter is required for neuromuscular development and function. Mol Cell Biol 2009; 29:5238-50. [PMID: 19635813 DOI: 10.1128/mcb.00245-09] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The vesicular acetylcholine (ACh) transporter (VAChT) mediates ACh storage by synaptic vesicles. However, the VAChT-independent release of ACh is believed to be important during development. Here we generated VAChT knockout mice and tested the physiological relevance of the VAChT-independent release of ACh. Homozygous VAChT knockout mice died shortly after birth, indicating that VAChT-mediated storage of ACh is essential for life. Indeed, synaptosomes obtained from brains of homozygous knockouts were incapable of releasing ACh in response to depolarization. Surprisingly, electrophysiological recordings at the skeletal-neuromuscular junction show that VAChT knockout mice present spontaneous miniature end-plate potentials with reduced amplitude and frequency, which are likely the result of a passive transport of ACh into synaptic vesicles. Interestingly, VAChT knockouts exhibit substantial increases in amounts of choline acetyltransferase, high-affinity choline transporter, and ACh. However, the development of the neuromuscular junction in these mice is severely affected. Mutant VAChT mice show increases in motoneuron and nerve terminal numbers. End plates are large, nerves exhibit abnormal sprouting, and muscle is necrotic. The abnormalities are similar to those of mice that cannot synthesize ACh due to a lack of choline acetyltransferase. Our results indicate that VAChT is essential to the normal development of motor neurons and the release of ACh.
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Glutamate, GABA and acetylcholine signaling components in the lamina of the Drosophila visual system. PLoS One 2008; 3:e2110. [PMID: 18464935 PMCID: PMC2373871 DOI: 10.1371/journal.pone.0002110] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Accepted: 03/11/2008] [Indexed: 02/01/2023] Open
Abstract
Synaptic connections of neurons in the Drosophila lamina, the most peripheral synaptic region of the visual system, have been comprehensively described. Although the lamina has been used extensively as a model for the development and plasticity of synaptic connections, the neurotransmitters in these circuits are still poorly known. Thus, to unravel possible neurotransmitter circuits in the lamina of Drosophila we combined Gal4 driven green fluorescent protein in specific lamina neurons with antisera to γ-aminobutyric acid (GABA), glutamic acid decarboxylase, a GABAB type of receptor, L-glutamate, a vesicular glutamate transporter (vGluT), ionotropic and metabotropic glutamate receptors, choline acetyltransferase and a vesicular acetylcholine transporter. We suggest that acetylcholine may be used as a neurotransmitter in both L4 monopolar neurons and a previously unreported type of wide-field tangential neuron (Cha-Tan). GABA is the likely transmitter of centrifugal neurons C2 and C3 and GABAB receptor immunoreactivity is seen on these neurons as well as the Cha-Tan neurons. Based on an rdl-Gal4 line, the ionotropic GABAA receptor subunit RDL may be expressed by L4 neurons and a type of tangential neuron (rdl-Tan). Strong vGluT immunoreactivity was detected in α-processes of amacrine neurons and possibly in the large monopolar neurons L1 and L2. These neurons also express glutamate-like immunoreactivity. However, antisera to ionotropic and metabotropic glutamate receptors did not produce distinct immunosignals in the lamina. In summary, this paper describes novel features of two distinct types of tangential neurons in the Drosophila lamina and assigns putative neurotransmitters and some receptors to a few identified neuron types.
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Colgan L, Liu H, Huang SY, Liu YJ. Dileucine motif is sufficient for internalization and synaptic vesicle targeting of vesicular acetylcholine transporter. Traffic 2008; 8:512-22. [PMID: 17451554 DOI: 10.1111/j.1600-0854.2007.00555.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Efficient cholinergic transmission requires accurate targeting of vesicular acetylcholine transporter (VAChT) to synaptic vesicles (SVs). However, the signals that regulate this vesicular targeting are not well characterized. Although previous studies suggest that the C-terminus of the transporter is required for its SV targeting, it is not clear whether this region is sufficient for this process. Furthermore, a synaptic vesicle-targeting motif (SVTM) within this sequence remains to be identified. Here we use a chimeric protein, TacA, between an unrelated plasma membrane protein, Tac, and the C-terminus of VAChT to demonstrate the sufficiency of the C-terminus for targeting to synaptic vesicle-like vesicles (SVLVs) in PC12 cells. TacA shows colocalization and cosedimentation with the SV marker synaptophysin. Deletion mutation analysis of TacA demonstrates that a short, dileucine motif-containing sequence is required and sufficient to direct this targeting. Dialanine mutation analysis within this sequence suggests indistinguishable signals for both internalization and SV sorting. Using additional chimeras as controls, we confirm the specificity of this region for SVLVs targeting. Therefore, we suggest that the dileucine-containing motif is sufficient as a dual signal for both internalization and SV targeting during VAChT trafficking.
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Affiliation(s)
- Lesley Colgan
- Department of Neurology, University of Pittsburgh School of Medicine, S512 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15213, USA
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Baqri R, Charan R, Schimmelpfeng K, Chavan S, Ray K. Kinesin-2 differentially regulates the anterograde axonal transports of acetylcholinesterase and choline acetyltransferase inDrosophila. ACTA ACUST UNITED AC 2006; 66:378-92. [PMID: 16408306 DOI: 10.1002/neu.20230] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) are involved in acetylcholine synthesis and degradation at pre- and postsynaptic compartments, respectively. Here we show that their anterograde transport in Drosophila larval ganglion is microtubule-dependent and occurs in two different time profiles. AChE transport is constitutive while that of ChAT occurs in a brief pulse during third instar larva stage. Mutations in the kinesin-2 motor subunit Klp64D and separate siRNA-mediated knock-outs of all the three kinesin-2 subunits disrupt the ChAT and AChE transports, and these antigens accumulate in discrete nonoverlapping punctae in neuronal cell bodies and axons. Quantification analysis further showed that mutations in Klp64D could independently affect the anterograde transport of AChE even before that of ChAT. Finally, ChAT and AChE were coimmunoprecipitated with the kinesin-2 subunits but not with each other. Altogether, these suggest that kinesin-2 independently transports AChE and ChAT within the same axon. It also implies that cargo availability could regulate the rate and frequency of transports by kinesin motors.
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Affiliation(s)
- Rehan Baqri
- Tata Institute of Fundamental Research, Mumbai 400 005, India
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Greer CL, Grygoruk A, Patton DE, Ley B, Romero-Calderon R, Chang HY, Houshyar R, Bainton RJ, Diantonio A, Krantz DE. A splice variant of the Drosophila vesicular monoamine transporter contains a conserved trafficking domain and functions in the storage of dopamine, serotonin, and octopamine. ACTA ACUST UNITED AC 2005; 64:239-58. [PMID: 15849736 DOI: 10.1002/neu.20146] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Vesicular monoamine transporters (VMATs) mediate the transport of dopamine (DA), serotonin (5HT), and other monoamines into secretory vesicles. The regulation of mammalian VMAT and the related vesicular acetylcholine transporter (VAChT) has been proposed to involve membrane trafficking, but the mechanisms remain unclear. To facilitate a genetic analysis of vesicular transporter function and regulation, we have cloned the Drosophila homolog of the vesicular monoamine transporter (dVMAT). We identify two mRNA splice variants (DVMAT-A and B) that differ at their C-terminus, the domain responsible for endocytosis of mammalian VMAT and VAChT. DVMAT-A contains trafficking motifs conserved in mammals but not C. elegans, and internalization assays indicate that the DVMAT-A C-terminus is involved in endocytosis. DVMAT-B contains a divergent C-terminal domain and is less efficiently internalized from the cell surface. Using in vitro transport assays, we show that DVMAT-A recognizes DA, 5HT, octopamine, tyramine, and histamine as substrates, and similar to mammalian VMAT homologs, is inhibited by the drug reserpine and the environmental toxins 2,2,4,5,6-pentachlorobiphenyl and heptachlor. We have developed a specific antiserum to DVMAT-A, and find that it localizes to dopaminergic and serotonergic neurons as well as octopaminergic, type II terminals at the neuromuscular junction. Surprisingly, DVMAT-A is co-expressed at type II terminals with the Drosophila vesicular glutamate transporter. Our data suggest that DVMAT-A functions as a vesicular transporter for DA, 5HT, and octopamine in vivo, and will provide a powerful invertebrate model for the study of transporter trafficking and regulation.
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Affiliation(s)
- Christina L Greer
- Department of Psychiatry and Biobehavioral Sciences, The David Geffen School of Medicine at UCLA, Gonda (Goldschmied) Center for Genetic and Neuroscience Research, 695 Charles Young Drive, Los Angeles, California 90095-1761, USA
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Yang H, Kunes S. Nonvesicular release of acetylcholine is required for axon targeting in the Drosophila visual system. Proc Natl Acad Sci U S A 2004; 101:15213-8. [PMID: 15469930 PMCID: PMC524039 DOI: 10.1073/pnas.0308141101] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Indexed: 01/08/2023] Open
Abstract
We report evidence for a developmental role of acetylcholine in axon pathfinding in the Drosophila visual system. Acetylcholine was detected on photoreceptor axons during their navigation to target sites in the brain, a time well before the formation of functional synapses. The pattern of photoreceptor axon projections was severely disrupted when acetylcholine synthesis or metabolism was altered or eliminated, or when transgenic alpha-bungarotoxin, a nicotinic acetylcholine receptor antagonist, was expressed in the developing eye or brain. The requirement for acetylcholine signaling exists before photoreceptor neurons form synaptic connections and does not require the function of vesicular acetylcholine transporter protein. That this early effect of acetylcholine is mediated through nonvesicular release is further supported by the observation that transgenic expression of tetanus toxin, a blocker of neurotransmitter release via synaptic vesicles, did not cause similar photoreceptor axon projection defects. These observations support the notion that a form of acetylcholine secretion mediates the behavior of growth cones during axon pathfinding.
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Affiliation(s)
- Hong Yang
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
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23
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Yu J, Fleming SL, Williams B, Williams EV, Li Z, Somma P, Rieder CL, Goldberg ML. Greatwall kinase: a nuclear protein required for proper chromosome condensation and mitotic progression in Drosophila. ACTA ACUST UNITED AC 2004; 164:487-92. [PMID: 14970188 PMCID: PMC2171981 DOI: 10.1083/jcb.200310059] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Mutations in the Drosophila gene greatwall cause improper chromosome condensation and delay cell cycle progression in larval neuroblasts. Chromosomes are highly undercondensed, particularly in the euchromatin, but nevertheless contain phosphorylated histone H3, condensin, and topoisomerase II. Cells take much longer to transit the period of chromosome condensation from late G2 through nuclear envelope breakdown. Mutant cells are also subsequently delayed at metaphase, due to spindle checkpoint activity. These mutant phenotypes are not caused by spindle aberrations, by global defects in chromosome replication, or by activation of a caffeine-sensitive checkpoint. The Greatwall proteins in insects and vertebrates are located in the nucleus and belong to the AGC family of serine/threonine protein kinases; the kinase domain of Greatwall is interrupted by a long stretch of unrelated amino acids.
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Affiliation(s)
- Jiangtao Yu
- Department of Molecular Biology and Genetics, Biotechnology Building, Cornell University, Ithaca, NY 14853-2703, USA
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Bravo D, Parsons SM. Microscopic kinetics and structure-function analysis in the vesicular acetylcholine transporter. Neurochem Int 2002; 41:285-9. [PMID: 12176068 DOI: 10.1016/s0197-0186(02)00058-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The vesicular acetylcholine transporter (VAChT) resides in synaptic vesicles of cholinergic nerve terminals. It carries out vesicular storage of ACh. The amount of ACh stored determines, along with other factors, the amount of ACh released. Knowledge of the structure-function relationship in VAChT might enable pharmacological regulation of ACh storage and release at the level of VAChT. To this end, a quantitative model for the individual steps in the overall transport cycle of VAChT has been developed. Because of the particular values of the microscopic rate constants in the model, structure-function analysis of VAChT can be misleading. Attempts to devise a pro-storage strategy to increase ACh release from cholinergic nerve terminals should take into account the microscopic kinetics of this transporter.
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Affiliation(s)
- Dawn Bravo
- Department of Chemistry and Biochemistry, The Neuroscience Research Institute, University of California, 93106-9510, Santa Barbara, CA, USA
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25
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Zhu H, Duerr JS, Varoqui H, McManus JR, Rand JB, Erickson JD. Analysis of point mutants in the Caenorhabditis elegans vesicular acetylcholine transporter reveals domains involved in substrate translocation. J Biol Chem 2001; 276:41580-7. [PMID: 11551909 DOI: 10.1074/jbc.m103550200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cholinergic neurotransmission depends upon the regulated release of acetylcholine. This requires the loading of acetylcholine into synaptic vesicles by the vesicular acetylcholine transporter (VAChT). Here, we identify point mutants in Caenorhabditis elegans that map to highly conserved regions of the VAChT gene of Caenorhabditis elegans (CeVAChT) (unc-17) and exhibit behavioral phenotypes consistent with a reduction in vesicular transport activity and neurosecretion. Several of these mutants express normal amounts of VAChT protein and exhibit appropriate targeting of VAChT to synaptic vesicles. By site-directed mutagenesis, we have replaced the conserved amino acid residues found in human VAChT with the mutated residue in CeVAChT and stably expressed these cDNAs in PC-12 cells. These mutants display selective defects in initial acetylcholine transport velocity (K(m)), with values ranging from 2- to 8-fold lower than that of the wild-type. One of these mutants has lost its specific interaction with vesamicol, a selective inhibitor of VAChT, and displays vesamicol-insensitive uptake of acetylcholine. The relative order of behavioral severity of the CeVAChT point mutants is identical to the order of reduced affinity of VAChT for acetylcholine in vitro. This indicates that specific structural changes in VAChT translate into specific alterations in the intrinsic parameters of transport and in the storage and synaptic release of acetylcholine in vivo.
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Affiliation(s)
- H Zhu
- Neuroscience Center and Departments of Ophthalmology and Pharmacology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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Kitamoto T. Conditional modification of behavior in Drosophila by targeted expression of a temperature-sensitive shibire allele in defined neurons. JOURNAL OF NEUROBIOLOGY 2001; 47:81-92. [PMID: 11291099 DOI: 10.1002/neu.1018] [Citation(s) in RCA: 618] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Behavior is a manifestation of temporally and spatially defined neuronal activities. To understand how behavior is controlled by the nervous system, it is important to identify the neuronal substrates responsible for these activities, and to elucidate how they are integrated into a functional circuit. I introduce a novel and general method to conditionally perturb anatomically defined neurons in intact Drosophila. In this method, a temperature-sensitive allele of shibire (shi(ts1)) is overexpressed in neuronal subsets using the GAL4/UAS system. Because the shi gene product is essential for synaptic vesicle recycling, and shi(ts1) is semidominant, a simple temperature shift should lead to fast and reversible effects on synaptic transmission of shi(ts1) expressing neurons. When shi(ts1) expression was directed to cholinergic neurons, adult flies showed a dramatic response to the restrictive temperature, becoming motionless within 2 min at 30 degrees C. This temperature-induced paralysis was reversible. After being shifted back to the permissive temperature, they readily regained their activity and started to walk in 1 min. When shi(ts1) was expressed in photoreceptor cells, adults and larvae exhibited temperature-dependent blindness. These observations show that the GAL4/UAS system can be used to express shi(ts1) in a specific subset of neurons to cause temperature-dependent changes in behavior. Because this method allows perturbation of the neuronal activities rapidly and reversibly in a spatially and temporally restricted manner, it will be useful to study the functional significance of particular neuronal subsets in the behavior of intact animals.
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Affiliation(s)
- T Kitamoto
- Division of Neurosciences, Beckman Research Institute of the City of Hope, 1450 East Duarte Road, Duarte, California 91010, USA.
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Erickson JD, Varoqui H. Molecular analysis of vesicular amine transporter function and targeting to secretory organelles. FASEB J 2000; 14:2450-8. [PMID: 11099462 DOI: 10.1096/fj.00-0206rev] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Vesicular transporters are responsible for the loading of neurotransmitters into specialized secretory organelles in neurons and neuroendocrine cells to make them available for regulated neurosecretion. The exocytotic release of neurotransmitter therefore depends on the functional activity of the vesicular transporters and their efficient sorting to these secretory organelles. Molecular analysis of vesicular transport proteins has revealed important information regarding structural domains responsible for their functional properties, including substrate specificity and trafficking to various classes of secretory vesicles. These studies have established the existence of an important functional relationship between transporter activity and presynaptic quantal neurosecretion.
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Affiliation(s)
- J D Erickson
- Neuroscience Center, Louisiania State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
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