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ADGRL1 haploinsufficiency causes a variable spectrum of neurodevelopmental disorders in humans and alters synaptic activity and behavior in a mouse model. Am J Hum Genet 2022; 109:1436-1457. [PMID: 35907405 PMCID: PMC9388395 DOI: 10.1016/j.ajhg.2022.06.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/22/2022] [Indexed: 02/06/2023] Open
Abstract
ADGRL1 (latrophilin 1), a well-characterized adhesion G protein-coupled receptor, has been implicated in synaptic development, maturation, and activity. However, the role of ADGRL1 in human disease has been elusive. Here, we describe ten individuals with variable neurodevelopmental features including developmental delay, intellectual disability, attention deficit hyperactivity and autism spectrum disorders, and epilepsy, all heterozygous for variants in ADGRL1. In vitro, human ADGRL1 variants expressed in neuroblastoma cells showed faulty ligand-induced regulation of intracellular Ca2+ influx, consistent with haploinsufficiency. In vivo, Adgrl1 was knocked out in mice and studied on two genetic backgrounds. On a non-permissive background, mice carrying a heterozygous Adgrl1 null allele exhibited neurological and developmental abnormalities, while homozygous mice were non-viable. On a permissive background, knockout animals were also born at sub-Mendelian ratios, but many Adgrl1 null mice survived gestation and reached adulthood. Adgrl1-/- mice demonstrated stereotypic behaviors, sexual dysfunction, bimodal extremes of locomotion, augmented startle reflex, and attenuated pre-pulse inhibition, which responded to risperidone. Ex vivo synaptic preparations displayed increased spontaneous exocytosis of dopamine, acetylcholine, and glutamate, but Adgrl1-/- neurons formed synapses in vitro poorly. Overall, our findings demonstrate that ADGRL1 haploinsufficiency leads to consistent developmental, neurological, and behavioral abnormalities in mice and humans.
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Avazzadeh S, McDonagh K, Reilly J, Wang Y, Boomkamp SD, McInerney V, Krawczyk J, Fitzgerald J, Feerick N, O'Sullivan M, Jalali A, Forman EB, Lynch SA, Ennis S, Cosemans N, Peeters H, Dockery P, O'Brien T, Quinlan LR, Gallagher L, Shen S. Increased Ca 2+ signaling in NRXN1α +/- neurons derived from ASD induced pluripotent stem cells. Mol Autism 2019; 10:52. [PMID: 31893021 PMCID: PMC6937972 DOI: 10.1186/s13229-019-0303-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/05/2019] [Indexed: 12/28/2022] Open
Abstract
Background Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a high co-morbidity of epilepsy and associated with hundreds of rare risk factors. NRXN1 deletion is among the commonest rare genetic factors shared by ASD, schizophrenia, intellectual disability, epilepsy, and developmental delay. However, how NRXN1 deletions lead to different clinical symptoms is unknown. Patient-derived cells are essential to investigate the functional consequences of NRXN1 lesions to human neurons in different diseases. Methods Skin biopsies were donated by five healthy donors and three ASD patients carrying NRXN1α+/− deletions. Seven control and six NRXN1α+/− iPSC lines were derived and differentiated into day 100 cortical excitatory neurons using dual SMAD inhibition. Calcium (Ca2+) imaging was performed using Fluo4-AM, and the properties of Ca2+ transients were compared between two groups of neurons. Transcriptome analysis was carried out to undercover molecular pathways associated with NRXN1α+/− neurons. Results NRXN1α+/− neurons were found to display altered calcium dynamics, with significantly increased frequency, duration, and amplitude of Ca2+ transients. Whole genome RNA sequencing also revealed altered ion transport and transporter activity, with upregulated voltage-gated calcium channels as one of the most significant pathways in NRXN1α+/− neurons identified by STRING and GSEA analyses. Conclusions This is the first report to show that human NRXN1α+/− neurons derived from ASD patients’ iPSCs present novel phenotypes of upregulated VGCCs and increased Ca2+ transients, which may facilitate the development of drug screening assays for the treatment of ASD.
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Affiliation(s)
- Sahar Avazzadeh
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Katya McDonagh
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Jamie Reilly
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Yanqin Wang
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland.,2Department of Physiology, College of Life Science, Hebei Normal University, Shijiazhuang, China
| | - Stephanie D Boomkamp
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Veronica McInerney
- 3HRB Clinical Research Facility, National University of Ireland (NUI), Galway, Ireland
| | - Janusz Krawczyk
- 4Department of Haematology, Galway University Hospital, Galway, Ireland
| | | | - Niamh Feerick
- 5School of Medicine, Trinity College Dublin, Dublin, Ireland
| | | | - Amirhossein Jalali
- 6School of Medicine, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Eva B Forman
- 7Children's University Hospital, Temple Street, Dublin, Ireland
| | - Sally A Lynch
- Department of Clinical Genetics, OLCHC, Dublin 12, Ireland.,9Children's University Hospital, Temple St, Dublin, Ireland.,10Academic Center on Rare Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Sean Ennis
- 11UCD Academic Centre on Rare Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Nele Cosemans
- 12Centre for Human Genetics, University Hospital Leuven, KU Leuven, 3000 Leuven, Belgium
| | - Hilde Peeters
- 10Academic Center on Rare Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Peter Dockery
- 13Centre for Microscopy and Imaging, Anatomy, School of Medicine, National University of Ireland (NUI), Galway, Ireland
| | - Timothy O'Brien
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Leo R Quinlan
- 14Physiology and Human Movement Laboratory, CÚRAM SFI Centre for Research in Medical Devices, School of Medicine, National University of Ireland (NUI), Galway, Ireland
| | | | - Sanbing Shen
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
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3
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Rahman MA, Manser C, Benlaouer O, Suckling J, Blackburn JK, Silva JP, Ushkaryov YA. C-terminal phosphorylation of latrophilin-1/ADGRL1 affects the interaction between its fragments. Ann N Y Acad Sci 2019; 1456:122-143. [PMID: 31553068 DOI: 10.1111/nyas.14242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 07/22/2019] [Accepted: 09/05/2019] [Indexed: 12/21/2022]
Abstract
Latrophilin-1 is an adhesion G protein-coupled receptor that mediates the effect of α-latrotoxin, causing massive release of neurotransmitters from nerve terminals and endocrine cells. Autoproteolysis cleaves latrophilin-1 into two parts: the extracellular N-terminal fragment (NTF) and the heptahelical C-terminal fragment (CTF). NTF and CTF can exist as independent proteins in the plasma membrane, but α-latrotoxin binding to NTF induces their association and G protein-mediated signaling. We demonstrate here that CTF in synapses is phosphorylated on multiple sites. Phosphorylated CTF has a high affinity for NTF and copurifies with it on affinity columns and sucrose density gradients. Dephosphorylated CTF has a lower affinity for NTF and can behave as a separate protein. α-Latrotoxin (and possibly other ligands of latrophilin-1) binds both to the NTF-CTF complex and receptor-like protein tyrosine phosphatase σ, bringing them together. This leads to CTF dephosphorylation and facilitates CTF release from the complex. We propose that ligand-dependent phosphorylation-dephosphorylation of latrophilin-1 could affect the interaction between its fragments and functions as a G protein-coupled receptor.
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Affiliation(s)
- M Atiqur Rahman
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Catherine Manser
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Ouafa Benlaouer
- School of Pharmacy, University of Kent, Chatham, United Kingdom
| | - Jason Suckling
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - John-Paul Silva
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Yuri A Ushkaryov
- Department of Life Sciences, Imperial College London, London, United Kingdom
- School of Pharmacy, University of Kent, Chatham, United Kingdom
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4
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Ushkaryov YA, Lelianova V, Vysokov NV. Catching Latrophilin With Lasso: A Universal Mechanism for Axonal Attraction and Synapse Formation. Front Neurosci 2019; 13:257. [PMID: 30967757 PMCID: PMC6438917 DOI: 10.3389/fnins.2019.00257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 03/05/2019] [Indexed: 11/24/2022] Open
Abstract
Latrophilin-1 (LPHN1) was isolated as the main high-affinity receptor for α-latrotoxin from black widow spider venom, a powerful presynaptic secretagogue. As an adhesion G-protein-coupled receptor, LPHN1 is cleaved into two fragments, which can behave independently on the cell surface, but re-associate upon binding the toxin. This triggers intracellular signaling that involves the Gαq/phospholipase C/inositol 1,4,5-trisphosphate cascade and an increase in cytosolic Ca2+, leading to vesicular exocytosis. Using affinity chromatography on LPHN1, we isolated its endogenous ligand, teneurin-2/Lasso. Both LPHN1 and Ten2/Lasso are expressed early in development and are enriched in neurons. LPHN1 primarily resides in axons, growth cones and presynaptic terminals, while Lasso largely localizes on dendrites. LPHN1 and Ten2/Lasso form a trans-synaptic receptor pair that has both structural and signaling functions. However, Lasso is proteolytically cleaved at multiple sites and its extracellular domain is partially released into the intercellular space, especially during neuronal development, suggesting that soluble Lasso has additional functions. We discovered that the soluble fragment of Lasso can diffuse away and bind to LPHN1 on axonal growth cones, triggering its redistribution on the cell surface and intracellular signaling which leads to local exocytosis. This causes axons to turn in the direction of spatio-temporal Lasso gradients, while LPHN1 knockout blocks this effect. These results suggest that the LPHN1-Ten2/Lasso pair can participate in long- and short-distance axonal guidance and synapse formation.
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Affiliation(s)
- Yuri A Ushkaryov
- Medway School of Pharmacy, University of Kent, Chatham, United Kingdom
| | - Vera Lelianova
- Medway School of Pharmacy, University of Kent, Chatham, United Kingdom
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Jeon J, Oh MA, Cho W, Yoon SH, Kim JY, Chung TD. Robust Induced Presynapse on Artificial Substrates as a Neural Interfacing Method. ACS APPLIED MATERIALS & INTERFACES 2019; 11:7764-7773. [PMID: 30707832 DOI: 10.1021/acsami.8b20405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Over the recent years, the development of neural interface systems has stuck to using electrical cues to stimulate neurons and read out neural signals, although neurons relay signals via chemical release and recognition at synapses. In addition, conventional neural interfaces are vulnerable to cell migration and glial encapsulation due to the absence of connection anchoring the neuron into the device unlike synapses, which are firmly sustained by protein bonding. To close this discrepancy, we conducted an intensive investigation into the induced synapse interface by employing engineered synaptic proteins from a neural interface perspective. The strong potential of induced synaptic differentiation as an emerging neural interfacing technique is demonstrated by exploring its structural features, chemical release kinetics, robustness, and scalability to the brain tissue. We show that the exocytosis kinetics of induced synapses is similar to that of endogenous synapses. Moreover, induced synapses show remarkable stability, despite cell migration and growth. The synapse-inducing technique has broad applications to cultured hippocampal and cortex tissues and suggests a promising method to integrate neural circuits with digital elements.
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Affiliation(s)
- Joohee Jeon
- Department of Chemistry , Seoul National University , Seoul 08826 , Republic of Korea
| | - Min-Ah Oh
- Department of Chemistry , Seoul National University , Seoul 08826 , Republic of Korea
| | - Wonkyung Cho
- Department of Chemistry , Seoul National University , Seoul 08826 , Republic of Korea
| | - Sun-Heui Yoon
- Department of Chemistry , Seoul National University , Seoul 08826 , Republic of Korea
| | - Ji Yong Kim
- Department of Chemistry , Seoul National University , Seoul 08826 , Republic of Korea
| | - Taek Dong Chung
- Department of Chemistry , Seoul National University , Seoul 08826 , Republic of Korea
- Advanced Institutes of Convergence Technology , Suwon-Si , Gyeonggi-do 16229 , Republic of Korea
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6
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Tan C, Lu NN, Wang CK, Chen DY, Sun NH, Lyu H, Körbelin J, Shi WX, Fukunaga K, Lu YM, Han F. Endothelium-Derived Semaphorin 3G Regulates Hippocampal Synaptic Structure and Plasticity via Neuropilin-2/PlexinA4. Neuron 2019; 101:920-937.e13. [PMID: 30685224 DOI: 10.1016/j.neuron.2018.12.036] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 11/05/2018] [Accepted: 12/21/2018] [Indexed: 01/12/2023]
Abstract
The proper interactions between blood vessels and neurons are critical for maintaining the strength of neural circuits and cognitive function. However, the precise molecular events underlying these interactions remain largely unknown. Here, we report that the selective knockout of semaphorin 3G (Sema3G) in endothelial cells impaired hippocampal-dependent memory and reduced dendritic spine density in CA1 neurons in mice; these effects were reversed after restoration of Sema3G levels in the hippocampus by AAV transfection. We further show that Sema3G increased excitatory synapse density via neuropilin-2/PlexinA4 signaling and through activation of Rac1. These results provide the first evidence that, in the central nervous system, endothelial Sema3G serves as a vascular-derived synaptic organizer that regulates synaptic plasticity and hippocampal-dependent memory. Our findings highlight the role of vascular endothelial cells in regulating cognitive function through intercellular communication with neurons in the hippocampus.
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Affiliation(s)
- Chao Tan
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Nan-Nan Lu
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Cheng-Kun Wang
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Dan-Yang Chen
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ning-He Sun
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Hang Lyu
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jakob Körbelin
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck 23562, Germany; Department of Oncology and Hematology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - Wei-Xing Shi
- Departments of Pharmaceutical, Administrative, and Basic Sciences, Schools of Pharmacy and Medicine, Loma Linda University Health, CA 92350, USA
| | - Kohji Fukunaga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Ying-Mei Lu
- School of Medicine, Zhejiang University City College, Hangzhou 310015, China; Department of Neurobiology, Nanjing Medical University, Nanjing 211166, China.
| | - Feng Han
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Cardiovascular & Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China.
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7
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Kainate receptor mediated presynaptic LTP in agranular insular cortex contributes to fear and anxiety in mice. Neuropharmacology 2018; 128:388-400. [DOI: 10.1016/j.neuropharm.2017.10.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 10/24/2017] [Accepted: 10/28/2017] [Indexed: 11/23/2022]
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8
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Zhang X, Rui M, Gan G, Huang C, Yi J, Lv H, Xie W. Neuroligin 4 regulates synaptic growth via the bone morphogenetic protein (BMP) signaling pathway at the Drosophila neuromuscular junction. J Biol Chem 2017; 292:17991-18005. [PMID: 28912273 PMCID: PMC5672027 DOI: 10.1074/jbc.m117.810242] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/12/2017] [Indexed: 01/26/2023] Open
Abstract
The neuroligin (Nlg) family of neural cell adhesion molecules is thought to be required for synapse formation and development and has been linked to the development of autism spectrum disorders in humans. In Drosophila melanogaster, mutations in the neuroligin 1–3 genes have been reported to induce synapse developmental defects at neuromuscular junctions (NMJs), but the role of neuroligin 4 (dnlg4) in synapse development has not been determined. Here, we report that the Drosophila neuroligin 4 (DNlg4) is different from DNlg1–3 in that it presynaptically regulates NMJ synapse development. Loss of dnlg4 results in reduced growth of NMJs with fewer synaptic boutons. The morphological defects caused by dnlg4 mutant are associated with a corresponding decrease in synaptic transmission efficacy. All of these defects could only be rescued when DNlg4 was expressed in the presynapse of NMJs. To understand the basis of DNlg4 function, we looked for genetic interactions and found connections with the components of the bone morphogenetic protein (BMP) signaling pathway. Immunostaining and Western blot analyses demonstrated that the regulation of NMJ growth by DNlg4 was due to the positive modulation of BMP signaling by DNlg4. Specifically, BMP type I receptor thickvein (Tkv) abundance was reduced in dnlg4 mutants, and immunoprecipitation assays showed that DNlg4 and Tkv physically interacted in vivo. Our study demonstrates that DNlg4 presynaptically regulates neuromuscular synaptic growth via the BMP signaling pathway by modulating Tkv.
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Affiliation(s)
- Xinwang Zhang
- From the Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu 210096, China.,the Department of Biology, Basic Medical School of Shanxi Medical University, Taiyuan, Shanxi 030001, China
| | - Menglong Rui
- From the Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu 210096, China.,Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, Jiangsu 210096, China, and
| | - Guangmin Gan
- Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, Jiangsu 210096, China, and
| | - Cong Huang
- From the Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu 210096, China
| | - Jukang Yi
- Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, Jiangsu 210096, China, and
| | - Huihui Lv
- From the Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu 210096, China.,Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, Jiangsu 210096, China, and
| | - Wei Xie
- From the Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu 210096, China, .,Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, Jiangsu 210096, China, and
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9
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Schreiner D, Savas JN, Herzog E, Brose N, de Wit J. Synapse biology in the 'circuit-age'-paths toward molecular connectomics. Curr Opin Neurobiol 2017; 42:102-110. [PMID: 28033531 PMCID: PMC5316339 DOI: 10.1016/j.conb.2016.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 12/07/2016] [Accepted: 12/08/2016] [Indexed: 11/23/2022]
Abstract
The neural connectome is a critical determinant of brain function. Circuits of precisely wired neurons, and the features of transmission at the synapses connecting them, are thought to dictate information processing in the brain. While recent technological advances now allow to define the anatomical and functional neural connectome at unprecedented resolution, the elucidation of the molecular mechanisms that establish the precise patterns of connectivity and the functional characteristics of synapses has remained challenging. Here, we describe the power and limitations of genetic approaches in the analysis of mechanisms that control synaptic connectivity and function, and discuss how recent methodological developments in proteomics might be used to elucidate the molecular synaptic connectome that is at the basis of the neural connectome.
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Affiliation(s)
- Dietmar Schreiner
- Biozentrum, University of Basel, Klingelbergstraße 50-70, 4056 Basel, Switzerland; Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
| | - Jeffrey N Savas
- Department of Neurology, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
| | - Etienne Herzog
- Univ. Bordeaux, IINS, UMR 5297, F-33000 Bordeaux, France; CNRS, IINS, UMR 5297, F-33000 Bordeaux, France
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Straße 3, 37075 Göttingen, Germany
| | - Joris de Wit
- VIB Center for Brain and Disease Research, Herestraat 49, 3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
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10
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Vysokov NV, Silva JP, Lelianova VG, Ho C, Djamgoz MB, Tonevitsky AG, Ushkaryov YA. The Mechanism of Regulated Release of Lasso/Teneurin-2. Front Mol Neurosci 2016; 9:59. [PMID: 27499734 PMCID: PMC4956664 DOI: 10.3389/fnmol.2016.00059] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 07/08/2016] [Indexed: 01/25/2023] Open
Abstract
Teneurins are large cell-surface receptors involved in axon guidance. Teneurin-2 (also known as latrophilin-1-associated synaptic surface organizer (Lasso)) interacts across the synaptic cleft with presynaptic latrophilin-1, an adhesion G-protein-coupled receptor that participates in regulating neurotransmitter release. Lasso-latrophilin-1 interaction mediates synapse formation and calcium signaling, highlighting the important role of this trans-synaptic receptor pair. However, Lasso is thought to be proteolytically cleaved within its ectodomain and released into the medium, making it unclear whether it acts as a proper cell-surface receptor or a soluble protein. We demonstrate here that during its intracellular processing Lasso is constitutively cleaved at a furin site within its ectodomain. The cleaved fragment, which encompasses almost the entire ectodomain of Lasso, is potentially soluble; however, it remains anchored on the cell surface via its non-covalent interaction with the transmembrane fragment of Lasso. Lasso is also constitutively cleaved within the intracellular domain (ICD). Finally, Lasso can be further proteolytically cleaved within the transmembrane domain. The third cleavage is regulated and releases the entire ectodomain of Lasso into the medium. The released ectodomain of Lasso retains its functional properties and binds latrophilin-1 expressed on other cells; this binding stimulates intracellular Ca2+ signaling in the target cells. Thus, Lasso not only serves as a bona fide cell-surface receptor, but also as a partially released target-derived signaling factor.
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Affiliation(s)
- Nickolai V Vysokov
- School of Pharmacy, University of KentChatham, UK; Division of Cell and Molecular Biology, Imperial College LondonLondon, UK
| | - John-Paul Silva
- Division of Cell and Molecular Biology, Imperial College London London, UK
| | - Vera G Lelianova
- School of Pharmacy, University of KentChatham, UK; Division of Cell and Molecular Biology, Imperial College LondonLondon, UK
| | - Claudia Ho
- Division of Cell and Molecular Biology, Imperial College London London, UK
| | - Mustafa B Djamgoz
- Division of Cell and Molecular Biology, Imperial College London London, UK
| | - Alexander G Tonevitsky
- Department of Translational Oncology, P.A. Hertzen Moscow Oncology Research Institute, National Center of Medical Radiological Research Moscow, Russia
| | - Yuri A Ushkaryov
- School of Pharmacy, University of KentChatham, UK; Division of Cell and Molecular Biology, Imperial College LondonLondon, UK
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11
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Savas JN, Ribeiro LF, Wierda KD, Wright R, DeNardo-Wilke LA, Rice HC, Chamma I, Wang YZ, Zemla R, Lavallée-Adam M, Vennekens KM, O'Sullivan ML, Antonios JK, Hall EA, Thoumine O, Attie AD, Yates JR, Ghosh A, de Wit J. The Sorting Receptor SorCS1 Regulates Trafficking of Neurexin and AMPA Receptors. Neuron 2015; 87:764-80. [PMID: 26291160 PMCID: PMC4692362 DOI: 10.1016/j.neuron.2015.08.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Revised: 06/16/2015] [Accepted: 08/03/2015] [Indexed: 01/01/2023]
Abstract
The formation, function, and plasticity of synapses require dynamic changes in synaptic receptor composition. Here, we identify the sorting receptor SorCS1 as a key regulator of synaptic receptor trafficking. Four independent proteomic analyses identify the synaptic adhesion molecule neurexin and the AMPA glutamate receptor (AMPAR) as major proteins sorted by SorCS1. SorCS1 localizes to early and recycling endosomes and regulates neurexin and AMPAR surface trafficking. Surface proteome analysis of SorCS1-deficient neurons shows decreased surface levels of these, and additional, receptors. Quantitative in vivo analysis of SorCS1-knockout synaptic proteomes identifies SorCS1 as a global trafficking regulator and reveals decreased levels of receptors regulating adhesion and neurotransmission, including neurexins and AMPARs. Consequently, glutamatergic transmission at SorCS1-deficient synapses is reduced due to impaired AMPAR surface expression. SORCS1 mutations have been associated with autism and Alzheimer disease, suggesting that perturbed receptor trafficking contributes to synaptic-composition and -function defects underlying synaptopathies.
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Affiliation(s)
- Jeffrey N Savas
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Luís F Ribeiro
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium; Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Keimpe D Wierda
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium; Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Rebecca Wright
- Neurobiology Section, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Laura A DeNardo-Wilke
- Neurobiology Section, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Heather C Rice
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium; Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Ingrid Chamma
- UMR 5297, Interdisciplinary Institute for Neuroscience, University of Bordeaux and Centre National de la Recherche Scientifique, 33000 Bordeaux, France
| | - Yi-Zhi Wang
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Roland Zemla
- School of Medicine, New York University, New York, New York 10016, USA
| | - Mathieu Lavallée-Adam
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Kristel M Vennekens
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium; Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Matthew L O'Sullivan
- Neurobiology Section, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Joseph K Antonios
- Neurobiology Section, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Elizabeth A Hall
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Olivier Thoumine
- UMR 5297, Interdisciplinary Institute for Neuroscience, University of Bordeaux and Centre National de la Recherche Scientifique, 33000 Bordeaux, France
| | - Alan D Attie
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Anirvan Ghosh
- Neurobiology Section, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA; Neuroscience Discovery, F. Hoffman-La Roche, 4070 Basel, Switzerland
| | - Joris de Wit
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium; Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium.
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12
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Abstract
The neurexin family of cell adhesion proteins consists of three members in
vertebrates and has homologs in several invertebrate species. In mammals, each
neurexin gene encodes an α-neurexin in which the extracellular portion is long,
and a β-neurexin in which the extracellular portion is short. As a result of
alternative splicing, both major isoforms can be transcribed in many variants,
contributing to distinct structural domains and variability. Neurexins act
predominantly at the presynaptic terminal in neurons and play essential roles in
neurotransmission and differentiation of synapses. Some of these functions require
the formation of trans-synaptic complexes with postsynaptic proteins such as
neuroligins, LRRTM proteins or cerebellin. In addition, rare mutations and
copy-number variations of human neurexin genes have been linked to autism and
schizophrenia, indicating that impairments of synaptic function sustained by
neurexins and their binding partners may be relevant to the pathomechanism of these
debilitating diseases.
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13
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Depner H, Lützkendorf J, Babkir HA, Sigrist SJ, Holt MG. Differential centrifugation-based biochemical fractionation of the Drosophila adult CNS. Nat Protoc 2014; 9:2796-808. [PMID: 25393777 DOI: 10.1038/nprot.2014.192] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Drosophila is widely used as a genetic model in questions of development, cellular function and disease. Genetic screens in flies have proven to be incredibly powerful in identifying crucial components for synapse formation and function, particularly in the case of the presynaptic release machinery. Although modern biochemical methods can identify individual proteins and lipids (and their binding partners), they have typically been excluded from use in Drosophila for technical reasons. To bridge this essential gap between genetics and biochemistry, we developed a fractionation method to isolate various parts of the synaptic machinery from Drosophila, thus allowing it to be studied in unprecedented biochemical detail. This is only possible because our protocol has unique advantages in terms of enriching and preserving endogenous protein complexes. The procedure involves decapitation of adult flies, homogenization and differential centrifugation of fly heads, which allow subsequent purification of presynaptic (and to a limited degree postsynaptic) components. It is designed to require only a rudimentary knowledge of biochemical fractionation, and it takes ∼3.5 h. The yield is typically 4 mg of synaptic membrane protein per gram of Drosophila heads.
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Affiliation(s)
- Harald Depner
- Institute for Biology - Genetics, Freie Universität Berlin, Berlin, Germany
| | - Janine Lützkendorf
- Institute for Biology - Genetics, Freie Universität Berlin, Berlin, Germany
| | - Husam A Babkir
- Institute for Biology - Genetics, Freie Universität Berlin, Berlin, Germany
| | - Stephan J Sigrist
- 1] Institute for Biology - Genetics, Freie Universität Berlin, Berlin, Germany. [2] NeuroCure Cluster of Excellence, Charité, Berlin, Germany
| | - Matthew G Holt
- Laboratory of Glia Biology, Vlaams Instituut voor Biotechnologie (VIB) Center for the Biology of Disease, Katholieke Universiteit (KU) Leuven, Leuven, Belgium
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14
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Yang X, Hou D, Jiang W, Zhang C. Intercellular protein-protein interactions at synapses. Protein Cell 2014; 5:420-44. [PMID: 24756565 PMCID: PMC4026422 DOI: 10.1007/s13238-014-0054-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 03/23/2014] [Indexed: 12/11/2022] Open
Abstract
Chemical synapses are asymmetric intercellular junctions through which neurons send nerve impulses to communicate with other neurons or excitable cells. The appropriate formation of synapses, both spatially and temporally, is essential for brain function and depends on the intercellular protein-protein interactions of cell adhesion molecules (CAMs) at synaptic clefts. The CAM proteins link pre- and post-synaptic sites, and play essential roles in promoting synapse formation and maturation, maintaining synapse number and type, accumulating neurotransmitter receptors and ion channels, controlling neuronal differentiation, and even regulating synaptic plasticity directly. Alteration of the interactions of CAMs leads to structural and functional impairments, which results in many neurological disorders, such as autism, Alzheimer's disease and schizophrenia. Therefore, it is crucial to understand the functions of CAMs during development and in the mature neural system, as well as in the pathogenesis of some neurological disorders. Here, we review the function of the major classes of CAMs, and how dysfunction of CAMs relates to several neurological disorders.
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Affiliation(s)
- Xiaofei Yang
- Key Laboratory of Cognitive Science, Laboratory of Membrane Ion Channels and Medicine, College of Biomedical Engineering, South-Central University for Nationalities, Wuhan, 430074 China
| | - Dongmei Hou
- Key Laboratory of Cognitive Science, Laboratory of Membrane Ion Channels and Medicine, College of Biomedical Engineering, South-Central University for Nationalities, Wuhan, 430074 China
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871 China
- PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871 China
| | - Wei Jiang
- Key Laboratory of Cognitive Science, Laboratory of Membrane Ion Channels and Medicine, College of Biomedical Engineering, South-Central University for Nationalities, Wuhan, 430074 China
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871 China
- PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871 China
| | - Chen Zhang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871 China
- PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871 China
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15
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Abstract
Direct electrical access to presynaptic ion channels has hitherto been limited to large specialized terminals such as the calyx of Held or hippocampal mossy fiber bouton. The electrophysiology and ion-channel complement of far more abundant small synaptic terminals (≤1 μm) remain poorly understood. Here we report a method based on superresolution scanning ion conductance imaging of small synapses in culture at approximately 100–150 nm 3D resolution, which allows presynaptic patch-clamp recordings in all four configurations (cell-attached, inside-out, outside-out, and whole-cell). Using this technique, we report presynaptic recordings of K+, Na+, Cl−, and Ca2+ channels. This semiautomated approach allows direct investigation of the distribution and properties of presynaptic ion channels at small central synapses. Video Abstract
Topographic imaging of live synaptic boutons at nanoscale resolution Cell-attached patch-clamp recordings of ion channels in small central synapses Whole-cell small presynaptic bouton recordings
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16
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Boyken J, Grønborg M, Riedel D, Urlaub H, Jahn R, Chua JJE. Molecular profiling of synaptic vesicle docking sites reveals novel proteins but few differences between glutamatergic and GABAergic synapses. Neuron 2013; 78:285-97. [PMID: 23622064 DOI: 10.1016/j.neuron.2013.02.027] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2013] [Indexed: 11/30/2022]
Abstract
Neurotransmission involves calcium-triggered fusion of docked synaptic vesicles at specialized presynaptic release sites. While many of the participating proteins have been identified, the molecular composition of these sites has not been characterized comprehensively. Here, we report a procedure to biochemically isolate fractions highly enriched in docked synaptic vesicles. The fraction is largely free of postsynaptic proteins and most other organelles while containing most known synaptic vesicle and active zone proteins. Numerous presynaptic transmembrane proteins were also identified, together with over 30 uncharacterized proteins, many of which are evolutionarily conserved. Quantitative proteomic comparison of glutamate- and GABA-specific docking complexes revealed that, except of neurotransmitter-specific enzymes and transporters, only few proteins were selectively enriched in either fraction. We conclude that the core machinery involved in vesicle docking and exocytosis does not show compositional differences between the two types of synapses.
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Affiliation(s)
- Janina Boyken
- Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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17
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Drosophila neuroligin 2 is required presynaptically and postsynaptically for proper synaptic differentiation and synaptic transmission. J Neurosci 2013; 32:16018-30. [PMID: 23136438 DOI: 10.1523/jneurosci.1685-12.2012] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Trans-synaptic adhesion between Neurexins (Nrxs) and Neuroligins (Nlgs) is thought to be required for proper synapse organization and modulation, and mutations in several human Nlgs have shown association with autism spectrum disorders. Here we report the generation and phenotypic characterization of Drosophila neuroligin 2 (dnlg2) mutants. Loss of dnlg2 results in reduced bouton numbers, aberrant presynaptic and postsynaptic development at neuromuscular junctions (NMJs), and impaired synaptic transmission. In dnlg2 mutants, the evoked responses are decreased in amplitude, whereas the total active zone (AZ) numbers at the NMJ are comparable to wild type, suggesting a decrease in the release probability. Ultrastructurally, the presynaptic AZ number per bouton area and the postsynaptic density area are both increased in dnlg2 mutants, whereas the subsynaptic reticulum is reduced in volume. We show that both presynaptic and postsynaptic expression of Dnlg2 is required to restore synaptic growth and function in dnlg2 mutants. Postsynaptic expression of Dnlg2 in dnlg2 mutants and wild type leads to reduced bouton growth whereas presynaptic and postsynaptic overexpression in wild-type animals results in synaptic overgrowth. Since Nlgs have been shown to bind to Nrxs, we created double mutants. These mutants are viable and display phenotypes that closely resemble those of dnlg2 and dnrx single mutants. Our results provide compelling evidence that Dnlg2 functions both presynaptically and postsynaptically together with Neurexin to determine the proper number of boutons as well as the number of AZs and size of synaptic densities during the development of NMJs.
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18
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A cis-complex of NB-2/contactin-5 with amyloid precursor-like protein 1 is localized on the presynaptic membrane. Neurosci Lett 2012; 510:148-53. [DOI: 10.1016/j.neulet.2012.01.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Revised: 01/10/2012] [Accepted: 01/11/2012] [Indexed: 01/06/2023]
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19
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Mosedale M, Egodage S, Calma RC, Chi NW, Chessler SD. Neurexin-1α contributes to insulin-containing secretory granule docking. J Biol Chem 2012; 287:6350-61. [PMID: 22235116 DOI: 10.1074/jbc.m111.299081] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Neurexins are a family of transmembrane, synaptic adhesion molecules. In neurons, neurexins bind to both sub-plasma membrane and synaptic vesicle-associated constituents of the secretory machinery, play a key role in the organization and stabilization of the presynaptic active zone, and help mediate docking of synaptic vesicles. We have previously shown that neurexins, like many other protein constituents of the neurotransmitter exocytotic machinery, are expressed in pancreatic β cells. We hypothesized that the role of neurexins in β cells parallels their role in neurons, with β-cell neurexins helping to mediate insulin granule docking and secretion. Here we demonstrate that β cells express a more restricted pattern of neurexin transcripts than neurons, with a clear predominance of neurexin-1α expressed in isolated islets. Using INS-1E β cells, we found that neurexin-1α interacts with membrane-bound components of the secretory granule-docking machinery and with the granule-associated protein granuphilin. Decreased expression of neurexin-1α, like decreased expression of granuphilin, reduces granule docking at the β-cell membrane and improves insulin secretion. Perifusion of neurexin-1α KO mouse islets revealed a significant increase in second-phase insulin secretion with a trend toward increased first-phase secretion. Upon glucose stimulation, neurexin-1α protein levels decrease. This glucose-induced down-regulation may enhance glucose-stimulated insulin secretion. We conclude that neurexin-1α is a component of the β-cell secretory machinery and contributes to secretory granule docking, most likely through interactions with granuphilin. Neurexin-1α is the only transmembrane component of the docking machinery identified thus far. Our findings provide new insights into the mechanisms of insulin granule docking and exocytosis.
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Affiliation(s)
- Merrie Mosedale
- Pediatric Diabetes Research Center, Veterans Affairs San Diego Healthcare System, University of California San Diego, La Jolla, California 92093, USA
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20
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Chen WS, Villaflores OB, Lu CF, Wu HI, Chen YJ, Teng CY, Chang YC, Chang SL, Wu TY. Functional expression of rat neuroligin-1 extracellular fragment by a bi-cistronic baculovirus expression vector. Protein Expr Purif 2012; 81:18-24. [PMID: 21911064 DOI: 10.1016/j.pep.2011.08.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2011] [Revised: 08/20/2011] [Accepted: 08/22/2011] [Indexed: 10/17/2022]
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21
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Bukalo O, Dityatev A. Synaptic Cell Adhesion Molecules. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 970:97-128. [DOI: 10.1007/978-3-7091-0932-8_5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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22
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Knight D, Xie W, Boulianne GL. Neurexins and neuroligins: recent insights from invertebrates. Mol Neurobiol 2011; 44:426-40. [PMID: 22037798 PMCID: PMC3229692 DOI: 10.1007/s12035-011-8213-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 10/17/2011] [Indexed: 11/28/2022]
Abstract
During brain development, each neuron must find and synapse with the correct pre- and postsynaptic partners. The complexity of these connections and the relatively large distances some neurons must send their axons to find the correct partners makes studying brain development one of the most challenging, and yet fascinating disciplines in biology. Furthermore, once the initial connections have been made, the neurons constantly remodel their dendritic and axonal arbours in response to changing demands. Neurexin and neuroligin are two cell adhesion molecules identified as important regulators of this process. The importance of these genes in the development and modulation of synaptic connectivity is emphasised by the observation that mutations in these genes in humans have been associated with cognitive disorders such as Autism spectrum disorders, Tourette syndrome and Schizophrenia. The present review will discuss recent advances in our understanding of the role of these genes in synaptic development and modulation, and in particular, we will focus on recent work in invertebrate models, and how these results relate to studies in mammals.
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Affiliation(s)
- David Knight
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada
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23
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Latrophilin 1 and its endogenous ligand Lasso/teneurin-2 form a high-affinity transsynaptic receptor pair with signaling capabilities. Proc Natl Acad Sci U S A 2011; 108:12113-8. [PMID: 21724987 DOI: 10.1073/pnas.1019434108] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Latrophilin 1 (LPH1), a neuronal receptor of α-latrotoxin, is implicated in neurotransmitter release and control of presynaptic Ca(2+). As an "adhesion G-protein-coupled receptor," LPH1 can convert cell surface interactions into intracellular signaling. To examine the physiological functions of LPH1, we used LPH1's extracellular domain to purify its endogenous ligand. A single protein of ∼275 kDa was isolated from rat brain and termed Lasso. Peptide sequencing and molecular cloning have shown that Lasso is a splice variant of teneurin-2, a brain-specific orphan cell surface receptor with a function in neuronal pathfinding and synaptogenesis. We show that LPH1 and Lasso interact strongly and specifically. They are always copurified from rat brain extracts. Coculturing cells expressing LPH1 with cells expressing Lasso leads to their mutual attraction and formation of multiple junctions to which both proteins are recruited. Cells expressing LPH1 form chimerical synapses with hippocampal neurons in cocultures; LPH1 and postsynaptic neuronal protein PSD-95 accumulate on opposite sides of these structures. Immunoblotting and immunoelectron microscopy of purified synapses and immunostaining of cultured hippocampal neurons show that LPH1 and Lasso are enriched in synapses; in both systems, LPH1 is presynaptic, whereas Lasso is postsynaptic. A C-terminal fragment of Lasso interacts with LPH1 and induces Ca(2+) signals in presynaptic boutons of hippocampal neurons and in neuroblastoma cells expressing LPH1. Thus, LPH1 and Lasso can form transsynaptic complexes capable of inducing presynaptic Ca(2+) signals, which might affect synaptic functions.
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24
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Abstract
Recent studies have identified the leucine rich repeat protein LRRTM2 as a post-synaptic ligand of Neurexins. Neurexins also bind the post-synaptic adhesion molecules, Neuroligins. All three families of genes have been implicated in the etiologies of neurodevelopmental disorders, specifically autism spectrum disorders and schizophrenia. Does the binding promiscuity of Neurexins now suggest complex cooperativity or redundancy at the synapse? While recent studies in primary neuronal cultures and also systematic extracellular protein interaction screens suggest summative effects of these systems, we propose that studying these interactions in the developing zebrafish embryo or larvae may shed more light on their functions during synaptogenesis in vivo. These gene families have recently been extensively characterized in zebrafish, demonstrating high sequence conservation with the human genes. The simpler circuitry of the zebrafish, together with the characterization of the expression patterns down to single, identifiable neurons and the ability to knock-down or over-express multiple genes in a rapid way lend themselves to dissecting complex interaction pathways. Furthermore, the capability of performing high-throughput drug screens suggests that these small vertebrates may prove extremely useful in identifying pharmacological approaches to treating autism spectrum disorders.
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Affiliation(s)
| | - Philip Washbourne
- Institute of Neuroscience, University of Oregon, Eugene OR 97403, USA
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25
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Differential expression of presynaptic genes in a rat model of postnatal hypoxia: relevance to schizophrenia. Eur Arch Psychiatry Clin Neurosci 2010; 260 Suppl 2:S81-9. [PMID: 20945070 PMCID: PMC2965359 DOI: 10.1007/s00406-010-0159-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Accepted: 08/04/2010] [Indexed: 02/02/2023]
Abstract
Obstetric complications play a role in the pathophysiology of schizophrenia. However, the biological consequences during neurodevelopment until adulthood are unknown. Microarrays have been used for expression profiling in four brain regions of a rat model of neonatal hypoxia as a common factor of obstetric complications. Animals were repeatedly exposed to chronic hypoxia from postnatal (PD) day 4 through day 8 and killed at the age of 150 days. Additional groups of rats were treated with clozapine from PD 120-150. Self-spotted chips containing 340 cDNAs related to the glutamate system ("glutamate chips") were used. The data show differential (up and down) regulations of numerous genes in frontal (FR), temporal (TE) and parietal cortex (PAR), and in caudate putamen (CPU), but evidently many more genes are upregulated in frontal and temporal cortex, whereas in parietal cortex the majority of genes are downregulated. Because of their primary presynaptic occurrence, five differentially expressed genes (CPX1, NPY, NRXN1, SNAP-25, and STX1A) have been selected for comparisons with clozapine-treated animals by qRT-PCR. Complexin 1 is upregulated in FR and TE cortex but unchanged in PAR by hypoxic treatment. Clozapine downregulates it in FR but upregulates it in PAR cortex. Similarly, syntaxin 1A was upregulated in FR, but downregulated in TE and unchanged in PAR cortex, whereas clozapine downregulated it in FR but upregulated it in PAR cortex. Hence, hypoxia alters gene expression regionally specific, which is in agreement with reports on differentially expressed presynaptic genes in schizophrenia. Chronic clozapine treatment may contribute to normalize synaptic connectivity.
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26
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Zhao H, Xiao S, Kong X, Wang J, Cao X, Gencheng W, Loh HH, Law PY. Neuron-glial cell communication in the traumatic stress-induced immunomodulation. Synapse 2010; 65:433-40. [DOI: 10.1002/syn.20861] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 08/16/2010] [Indexed: 11/08/2022]
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27
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Abstract
For more than three decades, the venom of the black widow spider and its principal active components, latrotoxins, have been used to induce release of neurotransmitters and hormones and to study the mechanisms of exocytosis. Given the complex nature of alpha--latrotoxin (alpha-LTX) actions, this research has been continuously overshadowed by many enigmas, misconceptions and perpetual changes of the underlying hypotheses. Some of the toxin's mechanisms of action are still not completely understood. Despite all these difficulties, the extensive work of several generations of neurobiologists has brought about a great deal of fascinating insights into pre-synaptic processes and has led to the discovery of several novel proteins and synaptic systems. For example, alpha-LTX studies have contributed to the widespread acceptance of the vesicular theory of transmitter release. Pre-synaptic receptors for alpha-LTX--neurexins, latrophilins and protein tyrosine phosphatase sigma--and their endogenous ligands have now become centrepieces of their own areas of research, with a potential of uncovering new mechanisms of synapse formation and regulation that may have medical implications. However, any future success of alpha-LTX research will require a better understanding of this unusual natural tool and a more precise dissection of its multiple mechanisms.
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Affiliation(s)
- John-Paul Silva
- Division of Cell and Molecular Biology, Imperial College London, Exhibition Road, London, UK
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28
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A neuroligin-4 missense mutation associated with autism impairs neuroligin-4 folding and endoplasmic reticulum export. J Neurosci 2009; 29:10843-54. [PMID: 19726642 PMCID: PMC2777970 DOI: 10.1523/jneurosci.1248-09.2009] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Neuroligins (NLs) are postsynaptic cell-adhesion molecules essential for normal synapse function. Mutations in neuroligin-4 (NL4) (gene symbol: NLGN4) have been reported in some patients with autism spectrum disorder (ASD) and other neurodevelopmental impairments. However, the low frequency of NL4 mutations and the limited information about the affected patients and the functional consequences of their mutations cast doubt on the causal role of NL4 mutations in these disorders. Here, we describe two brothers with classical ASD who carry a single amino-acid substitution in NL4 (R87W). This substitution was absent from the brothers' asymptomatic parents, suggesting that it arose in the maternal germ line. R87 is conserved in all NL isoforms, and the R87W substitution is not observed in control individuals. At the protein level, the R87W substitution impaired glycosylation processing of NL4 expressed in HEK293 and COS cells, destabilized NL4, caused NL4 retention in the endoplasmic reticulum in non-neuronal cells and neurons, and blocked NL4 transport to the cell surface. As a result, the R87W substitution inactivated the synapse-formation activity of NL4 and abolished the functional effect of NL4 on synapse strength. Viewed together, these observations suggest that a point mutation in NL4 can cause ASD by a loss-of-function mechanism.
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29
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Neuroligin-1 performs neurexin-dependent and neurexin-independent functions in synapse validation. EMBO J 2009; 28:3244-55. [PMID: 19730411 DOI: 10.1038/emboj.2009.249] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 07/30/2009] [Indexed: 12/28/2022] Open
Abstract
Postsynaptic neuroligins are thought to perform essential functions in synapse validation and synaptic transmission by binding to, and dimerizing, presynaptic alpha- and beta-neurexins. To test this hypothesis, we examined the functional effects of neuroligin-1 mutations that impair only alpha-neurexin binding, block both alpha- and beta-neurexin binding, or abolish neuroligin-1 dimerization. Abolishing alpha-neurexin binding abrogated neuroligin-induced generation of neuronal synapses onto transfected non-neuronal cells in the so-called artificial synapse-formation assay, even though beta-neurexin binding was retained. Thus, in this assay, neuroligin-1 induces apparent synapse formation by binding to presynaptic alpha-neurexins. In transfected neurons, however, neither alpha- nor beta-neurexin binding was essential for the ability of postsynaptic neuroligin-1 to dramatically increase synapse density, suggesting a neurexin-independent mechanism of synapse formation. Moreover, neuroligin-1 dimerization was not required for either the non-neuronal or the neuronal synapse-formation assay. Nevertheless, both alpha-neurexin binding and neuroligin-1 dimerization were essential for the increase in apparent synapse size that is induced by neuroligin-1 in transfected neurons. Thus, neuroligin-1 performs diverse synaptic functions by mechanisms that include as essential components of alpha-neurexin binding and neuroligin dimerization, but extend beyond these activities.
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30
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Polarized targeting of neurexins to synapses is regulated by their C-terminal sequences. J Neurosci 2009; 28:12969-81. [PMID: 19036990 DOI: 10.1523/jneurosci.5294-07.2008] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Two families of cell-adhesion molecules, predominantly presynaptic neurexins and postsynaptic neuroligins, are important for the formation and functioning of synapses in the brain, and mutations in several genes encoding these transmembrane proteins have been found in autism patients. However, very little is known about how neurexins are targeted to synapses and which mechanisms regulate this process. Using various epitope-tagged neurexins in primary hippocampal neurons of wild-type and knock-out mice in vitro and in transgenic animals in vivo, we show that neurexins are trafficked throughout neurons via transport vesicles and the plasma membrane insertion of neurexins occurs preferentially in the axonal/synaptic compartment. We also observed that exit of neurexins from the ER/Golgi and correct targeting require their PDZ-binding motif at the C terminus, whereas two presumptive ER retention signals are inactive. The ubiquitous presence of neurexin-positive transport vesicles and absence of bassoon colabeling demonstrate that these carriers are not active zone precursor vesicles, but colocalization with CASK, RIM1alpha, and calcium channels suggests that they may carry additional components of the exocytotic machinery. Our data indicate that neurexins are delivered to synapses by a polarized and regulated targeting process that involves PDZ-domain mediated interactions, suggesting a novel pathway for the distribution of neurexins and other synaptic proteins.
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31
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Variations in excitatory and inhibitory postsynaptic protein content in rat cerebral cortex with respect to aging and cognitive status. Neuroscience 2008; 159:896-907. [PMID: 19105974 DOI: 10.1016/j.neuroscience.2008.11.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 11/20/2008] [Indexed: 11/21/2022]
Abstract
Age-related cognitive impairments are associated with structural and functional changes in the cerebral cortex. We have previously demonstrated in the rat that excitatory and inhibitory pre- and postsynaptic changes occur with respect to age and cognitive status; however, in aged cognitively impaired animals, we have shown a significant imbalance in postsynaptic markers of excitatory versus inhibitory synapses, using markers of excitatory versus inhibitory neurotransmitter-related scaffolding proteins [postsynaptic density-95 (PSD95)/synapse associated protein-90 (SAP90) and gephyrin, respectively]. The present study focuses on whether the expression of various excitatory and inhibitory postsynaptic proteins is affected by ageing and cognitive status. Thus, aged animals were segregated into aged cognitively impaired (AI) and aged cognitively unimpaired (AU) groups using the Morris water maze. We applied Western immunoblotting to reveal the expression patterns of a number of relevant excitatory and inhibitory receptors in the prefrontal and parietal cortices of young (Y), AU and AI animals, and performed semi-quantitative analyses to statistically tabulate changes among the three animal groups. A significant increase in the inhibitory postsynaptic scaffold protein, gephyrin, was observed in the parietal cortex of AI animals. Similarly, an increase in GABA(A) receptor subunit alpha1 was observed in the parietal cortex of AI animals. An increase in the excitatory N-methyl-d-aspartate receptor subunit N-methyl-d-aspartate receptor 1 expression was observed in the parietal cortex of AI animals, whereas a significant decrease in AMPA receptor subunit glutamate receptor 2 expression was found in the prefrontal cortex of AI animals. Finally, the excitatory, postsynaptic neuronal cell-adhesion receptor, neuroligin-1, was found to be significantly increased in both the prefrontal and parietal cortical areas of AI animals.
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Abstract
The brain processes information by transmitting signals at synapses, which connect neurons into vast networks of communicating cells. In these networks, synapses not only transmit signals but also transform and refine them. Neurexins and neuroligins are synaptic cell-adhesion molecules that connect presynaptic and postsynaptic neurons at synapses, mediate signalling across the synapse, and shape the properties of neural networks by specifying synaptic functions. In humans, alterations in genes encoding neurexins or neuroligins have recently been implicated in autism and other cognitive diseases, linking synaptic cell adhesion to cognition and its disorders.
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Affiliation(s)
- Thomas C Südhof
- Neuroscience Institute, Department of Molecular and Cellular Physiology, Stanford University, 1050 Arastradero Road B249, Palo Alto, California 94304, USA.
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Biswas S, Russell RJ, Jackson CJ, Vidovic M, Ganeshina O, Oakeshott JG, Claudianos C. Bridging the synaptic gap: neuroligins and neurexin I in Apis mellifera. PLoS One 2008; 3:e3542. [PMID: 18974885 PMCID: PMC2570956 DOI: 10.1371/journal.pone.0003542] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Accepted: 09/16/2008] [Indexed: 01/07/2023] Open
Abstract
Vertebrate studies show neuroligins and neurexins are binding partners in a trans-synaptic cell adhesion complex, implicated in human autism and mental retardation disorders. Here we report a genetic analysis of homologous proteins in the honey bee. As in humans, the honeybee has five large (31–246 kb, up to 12 exons each) neuroligin genes, three of which are tightly clustered. RNA analysis of the neuroligin-3 gene reveals five alternatively spliced transcripts, generated through alternative use of exons encoding the cholinesterase-like domain. Whereas vertebrates have three neurexins the bee has just one gene named neurexin I (400 kb, 28 exons). However alternative isoforms of bee neurexin I are generated by differential use of 12 splice sites, mostly located in regions encoding LNS subdomains. Some of the splice variants of bee neurexin I resemble the vertebrate α- and β-neurexins, albeit in vertebrates these forms are generated by alternative promoters. Novel splicing variations in the 3′ region generate transcripts encoding alternative trans-membrane and PDZ domains. Another 3′ splicing variation predicts soluble neurexin I isoforms. Neurexin I and neuroligin expression was found in brain tissue, with expression present throughout development, and in most cases significantly up-regulated in adults. Transcripts of neurexin I and one neuroligin tested were abundant in mushroom bodies, a higher order processing centre in the bee brain. We show neuroligins and neurexins comprise a highly conserved molecular system with likely similar functional roles in insects as vertebrates, and with scope in the honeybee to generate substantial functional diversity through alternative splicing. Our study provides important prerequisite data for using the bee as a model for vertebrate synaptic development.
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Affiliation(s)
- Sunita Biswas
- University of Queensland, Queensland Brain Institute, Brisbane, Queensland, Australia
- Australian National University, Research School of Biological Sciences, Canberra, Australian Capital Territory, Australia
- CSIRO Entomology, Black Mountain, Canberra, Australian Capital Territory, Australia
| | - Robyn J. Russell
- CSIRO Entomology, Black Mountain, Canberra, Australian Capital Territory, Australia
| | - Colin J. Jackson
- CSIRO Entomology, Black Mountain, Canberra, Australian Capital Territory, Australia
| | - Maria Vidovic
- Australian National University, Research School of Biological Sciences, Canberra, Australian Capital Territory, Australia
| | - Olga Ganeshina
- University of Queensland, Queensland Brain Institute, Brisbane, Queensland, Australia
| | - John G. Oakeshott
- CSIRO Entomology, Black Mountain, Canberra, Australian Capital Territory, Australia
| | - Charles Claudianos
- University of Queensland, Queensland Brain Institute, Brisbane, Queensland, Australia
- CSIRO Entomology, Black Mountain, Canberra, Australian Capital Territory, Australia
- * E-mail:
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