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Blanco-Redondo B, Nuwal N, Kneitz S, Nuwal T, Halder P, Liu Y, Ehmann N, Scholz N, Mayer A, Kleber J, Kähne T, Schmitt D, Sadanandappa MK, Funk N, Albertova V, Helfrich-Förster C, Ramaswami M, Hasan G, Kittel RJ, Langenhan T, Gerber B, Buchner E. Implications of the Sap47 null mutation for synapsin phosphorylation, longevity, climbing proficiency and behavioural plasticity in adult Drosophila. ACTA ACUST UNITED AC 2019; 222:jeb.203505. [PMID: 31488622 DOI: 10.1242/jeb.203505] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 08/29/2019] [Indexed: 12/18/2022]
Abstract
The Sap47 gene of Drosophila melanogaster encodes a highly abundant 47 kDa synaptic vesicle-associated protein. Sap47 null mutants show defects in synaptic plasticity and larval olfactory associative learning but the molecular function of Sap47 at the synapse is unknown. We demonstrate that Sap47 modulates the phosphorylation of another highly abundant conserved presynaptic protein, synapsin. Site-specific phosphorylation of Drosophila synapsin has repeatedly been shown to be important for behavioural plasticity but it was not known where these phospho-synapsin isoforms are localized in the brain. Here, we report the distribution of serine-6-phosphorylated synapsin in the adult brain and show that it is highly enriched in rings of synapses in the ellipsoid body and in large synapses near the lateral triangle. The effects of knockout of Sap47 or synapsin on olfactory associative learning/memory support the hypothesis that both proteins operate in the same molecular pathway. We therefore asked if this might also be true for other aspects of their function. We show that knockout of Sap47 but not synapsin reduces lifespan, whereas knockout of Sap47 and synapsin, either individually or together, affects climbing proficiency, as well as plasticity in circadian rhythms and sleep. Furthermore, electrophysiological assessment of synaptic properties at the larval neuromuscular junction (NMJ) reveals increased spontaneous synaptic vesicle fusion and reduced paired pulse facilitation in Sap47 and synapsin single and double mutants. Our results imply that Sap47 and synapsin cooperate non-uniformly in the control of synaptic properties in different behaviourally relevant neuronal networks of the fruitfly.
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Affiliation(s)
- Beatriz Blanco-Redondo
- Institute of Clinical Neurobiology, University of Würzburg, 97078 Würzburg, Germany .,Department of Neurobiology and Genetics, Biocenter of the University of Würzburg, 97074 Würzburg, Germany.,Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Leipzig University, 04103 Leipzig, Germany
| | - Nidhi Nuwal
- Department of Neurobiology and Genetics, Biocenter of the University of Würzburg, 97074 Würzburg, Germany
| | - Susanne Kneitz
- Department of Physiological Chemistry, Biocenter of the University of Würzburg, 97074 Würzburg, Germany
| | - Tulip Nuwal
- Department of Neurobiology and Genetics, Biocenter of the University of Würzburg, 97074 Würzburg, Germany
| | - Partho Halder
- Department of Neurobiology and Genetics, Biocenter of the University of Würzburg, 97074 Würzburg, Germany
| | - Yiting Liu
- Department of Neurobiology and Genetics, Biocenter of the University of Würzburg, 97074 Würzburg, Germany
| | - Nadine Ehmann
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, 97070 Würzburg, Germany.,Department of Animal Physiology, Institute of Biology, Leipzig University, 04103 Leipzig, Germany.,Carl-Ludwig-Institute for Physiology, Leipzig University, 04103 Leipzig, Germany
| | - Nicole Scholz
- Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Leipzig University, 04103 Leipzig, Germany.,Department of Neurophysiology, Institute of Physiology, University of Würzburg, 97070 Würzburg, Germany
| | - Annika Mayer
- Institute of Clinical Neurobiology, University of Würzburg, 97078 Würzburg, Germany
| | - Jörg Kleber
- Leibniz Institute of Neurobiology, 39118 Magdeburg, Germany
| | - Thilo Kähne
- Institute of Experimental Internal Medicine, Otto von Guericke University, 39120 Magdeburg, Germany
| | - Dominique Schmitt
- Institute of Clinical Neurobiology, University of Würzburg, 97078 Würzburg, Germany
| | - Madhumala K Sadanandappa
- Institute of Clinical Neurobiology, University of Würzburg, 97078 Würzburg, Germany.,National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India
| | - Natalja Funk
- Department of Neurobiology and Genetics, Biocenter of the University of Würzburg, 97074 Würzburg, Germany
| | - Viera Albertova
- Institute of Clinical Neurobiology, University of Würzburg, 97078 Würzburg, Germany.,Department of Neurobiology and Genetics, Biocenter of the University of Würzburg, 97074 Würzburg, Germany
| | - Charlotte Helfrich-Förster
- Department of Neurobiology and Genetics, Biocenter of the University of Würzburg, 97074 Würzburg, Germany
| | - Mani Ramaswami
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India
| | - Gaiti Hasan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India
| | - Robert J Kittel
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, 97070 Würzburg, Germany.,Department of Animal Physiology, Institute of Biology, Leipzig University, 04103 Leipzig, Germany.,Carl-Ludwig-Institute for Physiology, Leipzig University, 04103 Leipzig, Germany
| | - Tobias Langenhan
- Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Leipzig University, 04103 Leipzig, Germany.,Department of Neurophysiology, Institute of Physiology, University of Würzburg, 97070 Würzburg, Germany
| | - Bertram Gerber
- Leibniz Institute of Neurobiology, 39118 Magdeburg, Germany.,Institute of Biology, University of Magdeburg, 39120 Magdeburg, Germany.,Center for Behavioral Brain Sciences, 39106 Magdeburg, Germany
| | - Erich Buchner
- Institute of Clinical Neurobiology, University of Würzburg, 97078 Würzburg, Germany .,Department of Neurobiology and Genetics, Biocenter of the University of Würzburg, 97074 Würzburg, Germany
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Dos Santos-Pinto JRA, Arcuri HA, Esteves FG, Palma MS, Lubec G. Spider silk proteome provides insight into the structural characterization of Nephila clavipes flagelliform spidroin. Sci Rep 2018; 8:14674. [PMID: 30279551 PMCID: PMC6168590 DOI: 10.1038/s41598-018-33068-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 09/12/2018] [Indexed: 12/13/2022] Open
Abstract
The capture spiral of web from N. clavipes spider consists of a single type of spidroin - the flagelliform silk protein, a natural material representing a combination of strength and high elasticity. Flagelliform spider silk is the most extensible silk fibre produced by orb weaver spiders and the structure of this remarkable material is still largely unknown. In the present study we used a proteomic approach to elucidate the complete sequence and the post-translational modifications of flagelliform silk proteins. The long sequence of flagelliform silk protein presents 45 hydroxylated proline residues, which may contribute to explain the mechanoelastic property of these fibres, since they are located in the GPGGX motif. The 3D-structure of the protein was modelled considering the three domains together, i.e., the N- and C-terminal non-repetitive domains, and the central repetitive domain. In the resulting molecular model there is a predominance of random structures in the solid fibres of the silk protein. The N-terminal domain is composed of three α-helices and the C-terminal domain is composed of one small helical section. Proteomic data reported herein may be relevant for the development of novel approaches for the synthetic or recombinant production of novel silk-based spider polymers.
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Affiliation(s)
- José Roberto Aparecido Dos Santos-Pinto
- Center of the Study of Social Insects, Department of Biology, Institute of Biosciences of Rio Claro, São Paulo State University, Rio Claro, SP, 13500, Brazil
| | - Helen Andrade Arcuri
- Center of the Study of Social Insects, Department of Biology, Institute of Biosciences of Rio Claro, São Paulo State University, Rio Claro, SP, 13500, Brazil
| | - Franciele Grego Esteves
- Center of the Study of Social Insects, Department of Biology, Institute of Biosciences of Rio Claro, São Paulo State University, Rio Claro, SP, 13500, Brazil
| | - Mario Sergio Palma
- Center of the Study of Social Insects, Department of Biology, Institute of Biosciences of Rio Claro, São Paulo State University, Rio Claro, SP, 13500, Brazil.
| | - Gert Lubec
- Paracelsus Medical University, A 5020, Salzburg, Austria.
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Structural characterization of the major ampullate silk spidroin-2 protein produced by the spider Nephila clavipes. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:1444-54. [DOI: 10.1016/j.bbapap.2016.05.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 05/04/2016] [Accepted: 05/17/2016] [Indexed: 11/19/2022]
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Kleber J, Chen YC, Michels B, Saumweber T, Schleyer M, Kähne T, Buchner E, Gerber B. Synapsin is required to "boost" memory strength for highly salient events. ACTA ACUST UNITED AC 2015; 23:9-20. [PMID: 26670182 PMCID: PMC4749839 DOI: 10.1101/lm.039685.115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/28/2015] [Indexed: 12/11/2022]
Abstract
Synapsin is an evolutionarily conserved presynaptic phosphoprotein. It is encoded by only one gene in the Drosophila genome and is expressed throughout the nervous system. It regulates the balance between reserve and releasable vesicles, is required to maintain transmission upon heavy demand, and is essential for proper memory function at the behavioral level. Task-relevant sensorimotor functions, however, remain intact in the absence of Synapsin. Using an odor–sugar reward associative learning paradigm in larval Drosophila, we show that memory scores in mutants lacking Synapsin (syn97) are lower than in wild-type animals only when more salient, higher concentrations of odor or of the sugar reward are used. Furthermore, we show that Synapsin is selectively required for larval short-term memory. Thus, without Synapsin Drosophila larvae can learn and remember, but Synapsin is required to form memories that match in strength to event salience—in particular to a high saliency of odors, of rewards, or the salient recency of an event. We further show that the residual memory scores upon a lack of Synapsin are not further decreased by an additional lack of the Sap47 protein. In combination with mass spectrometry data showing an up-regulated phosphorylation of Synapsin in the larval nervous system upon a lack of Sap47, this is suggestive of a functional interdependence of Synapsin and Sap47.
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Affiliation(s)
- Jörg Kleber
- Leibniz Institut für Neurobiologie (LIN), Abteilung Genetik von Lernen und Gedächtnis, 39118 Magdeburg, Germany
| | - Yi-Chun Chen
- Leibniz Institut für Neurobiologie (LIN), Abteilung Genetik von Lernen und Gedächtnis, 39118 Magdeburg, Germany
| | - Birgit Michels
- Leibniz Institut für Neurobiologie (LIN), Abteilung Genetik von Lernen und Gedächtnis, 39118 Magdeburg, Germany
| | - Timo Saumweber
- Leibniz Institut für Neurobiologie (LIN), Abteilung Genetik von Lernen und Gedächtnis, 39118 Magdeburg, Germany
| | - Michael Schleyer
- Leibniz Institut für Neurobiologie (LIN), Abteilung Genetik von Lernen und Gedächtnis, 39118 Magdeburg, Germany
| | - Thilo Kähne
- Otto von Guericke Universität Magdeburg, Institut für Experimentelle Innere Medizin, 39120 Magdeburg, Germany
| | - Erich Buchner
- Institut für Klinische Neurobiologie, 97078 Würzburg, Germany
| | - Bertram Gerber
- Leibniz Institut für Neurobiologie (LIN), Abteilung Genetik von Lernen und Gedächtnis, 39118 Magdeburg, Germany Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany Otto von Guericke Universität Magdeburg, Institut für Biologie, 39106 Magdeburg, Germany
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5
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Winther ÅME, Vorontsova O, Rees KA, Näreoja T, Sopova E, Jiao W, Shupliakov O. An Endocytic Scaffolding Protein together with Synapsin Regulates Synaptic Vesicle Clustering in the Drosophila Neuromuscular Junction. J Neurosci 2015; 35:14756-70. [PMID: 26538647 PMCID: PMC6605226 DOI: 10.1523/jneurosci.1675-15.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 09/16/2015] [Accepted: 09/25/2015] [Indexed: 11/21/2022] Open
Abstract
Many endocytic proteins accumulate in the reserve pool of synaptic vesicles (SVs) in synapses and relocalize to the endocytic periactive zone during neurotransmitter release. Currently little is known about their functions outside the periactive zone. Here we show that in the Drosophila neuromuscular junction (NMJ), the endocytic scaffolding protein Dap160 colocalizes during the SV cycle and forms a functional complex with the SV-associated phosphoprotein synapsin, previously implicated in SV clustering. This direct interaction is strongly enhanced under phosphorylation-promoting conditions and is essential for proper localization of synapsin at NMJs. In a dap160 rescue mutant lacking the interaction between Dap160 and synapsin, perturbed reclustering of SVs during synaptic activity is observed. Our data indicate that in addition to the function in endocytosis, Dap160 is a component of a network of protein-protein interactions that serves for clustering of SVs in conjunction with synapsin. During the SV cycle, Dap160 interacts with synapsin dispersed from SVs and helps direct synapsin back to vesicles. The proteins function in synergy to achieve efficient clustering of SVs in the reserve pool. SIGNIFICANCE STATEMENT We provide the first evidence for the function of the SH3 domain interaction in synaptic vesicle (SV) organization at the synaptic active zone. Using Drosophila neuromuscular junction as a model synapse, we describe the molecular mechanism that enables the protein implicated in SV clustering, synapsin, to return to the pool of vesicles during neurotransmitter release. We also identify the endocytic scaffolding complex that includes Dap160 as a regulator of the events linking exocytosis and endocytosis in synapses.
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Affiliation(s)
- Åsa M E Winther
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Olga Vorontsova
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Kathryn A Rees
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Tuomas Näreoja
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Elena Sopova
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Wei Jiao
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
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6
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dos Santos-Pinto JRA, Arcuri HA, Priewalder H, Salles HC, Palma MS, Lubec G. Structural Model for the Spider Silk Protein Spidroin-1. J Proteome Res 2015. [DOI: 10.1021/acs.jproteome.5b00243] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- José Roberto Aparecido dos Santos-Pinto
- Center
of the Study of Social Insects, Department of Biology, Institute of
Biosciences of Rio Claro, São Paulo State University, Rio Claro, SP 13500, Brazil
- Department
of Pediatrics, Medical University of Vienna, Vienna 1090, Austria
| | - Helen Andrade Arcuri
- Center
of the Study of Social Insects, Department of Biology, Institute of
Biosciences of Rio Claro, São Paulo State University, Rio Claro, SP 13500, Brazil
| | - Helga Priewalder
- Department
of Paleontology, Geological Survey of Austria, Vienna 1230, Austria
| | - Heliana Clara Salles
- Center
of the Study of Social Insects, Department of Biology, Institute of
Biosciences of Rio Claro, São Paulo State University, Rio Claro, SP 13500, Brazil
| | - Mario Sergio Palma
- Center
of the Study of Social Insects, Department of Biology, Institute of
Biosciences of Rio Claro, São Paulo State University, Rio Claro, SP 13500, Brazil
| | - Gert Lubec
- Department
of Pediatrics, Medical University of Vienna, Vienna 1090, Austria
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Abstract
Adverse life events can induce two kinds of memory with opposite valence, dependent on timing: "negative" memories for stimuli preceding them and "positive" memories for stimuli experienced at the moment of "relief." Such punishment memory and relief memory are found in insects, rats, and man. For example, fruit flies (Drosophila melanogaster) avoid an odor after odor-shock training ("forward conditioning" of the odor), whereas after shock-odor training ("backward conditioning" of the odor) they approach it. Do these timing-dependent associative processes share molecular determinants? We focus on the role of Synapsin, a conserved presynaptic phosphoprotein regulating the balance between the reserve pool and the readily releasable pool of synaptic vesicles. We find that a lack of Synapsin leaves task-relevant sensory and motor faculties unaffected. In contrast, both punishment memory and relief memory scores are reduced. These defects reflect a true lessening of associative memory strength, as distortions in nonassociative processing (e.g., susceptibility to handling, adaptation, habituation, sensitization), discrimination ability, and changes in the time course of coincidence detection can be ruled out as alternative explanations. Reductions in punishment- and relief-memory strength are also observed upon an RNAi-mediated knock-down of Synapsin, and are rescued both by acutely restoring Synapsin and by locally restoring it in the mushroom bodies of mutant flies. Thus, both punishment memory and relief memory require the Synapsin protein and in this sense share genetic and molecular determinants. We note that corresponding molecular commonalities between punishment memory and relief memory in humans would constrain pharmacological attempts to selectively interfere with excessive associative punishment memories, e.g., after traumatic experiences.
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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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Synapsin function in GABA-ergic interneurons is required for short-term olfactory habituation. J Neurosci 2013; 33:16576-85. [PMID: 24133261 DOI: 10.1523/jneurosci.3142-13.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In Drosophila, short-term (STH) and long-term habituation (LTH) of olfactory avoidance behavior are believed to arise from the selective potentiation of GABAergic synapses between multiglomerular local circuit interneurons (LNs) and projection neurons in the antennal lobe. However, the underlying mechanisms remain poorly understood. Here, we show that synapsin (syn) function is necessary for STH and that syn(97)-null mutant defects in STH can be rescued by syn(+) cDNA expression solely in the LN1 subset of GABAergic local interneurons. As synapsin is a synaptic vesicle-clustering phosphoprotein, these observations identify a presynaptic mechanism for STH as well as the inhibitory interneurons in which this mechanism is deployed. Serine residues 6 and/or 533, potential kinase target sites of synapsin, are necessary for synapsin function suggesting that synapsin phosphorylation is essential for STH. Consistently, biochemical analyses using a phospho-synapsin-specific antiserum show that synapsin is a target of Ca(2+) calmodulin-dependent kinase II (CaMKII) phosphorylation in vivo. Additional behavioral and genetic observations demonstrate that CaMKII function is necessary in LNs for STH. Together, these data support a model in which CaMKII-mediated synapsin phosphorylation in LNs induces synaptic vesicle mobilization and thereby presynaptic facilitation of GABA release that underlies olfactory STH. Finally, the striking observation that LTH occurs normally in syn(97) mutants indicates that signaling pathways for STH and LTH diverge upstream of synapsin function in GABAergic interneurons.
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Diegelmann S, Klagges B, Michels B, Schleyer M, Gerber B. Maggot learning and Synapsin function. ACTA ACUST UNITED AC 2013; 216:939-51. [PMID: 23447663 DOI: 10.1242/jeb.076208] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Drosophila larvae are focused on feeding and have few neurons. Within these bounds, however, there still are behavioural degrees of freedom. This review is devoted to what these elements of flexibility are, and how they come about. Regarding odour-food associative learning, the emerging working hypothesis is that when a mushroom body neuron is activated as a part of an odour-specific set of mushroom body neurons, and coincidently receives a reinforcement signal carried by aminergic neurons, the AC-cAMP-PKA cascade is triggered. One substrate of this cascade is Synapsin, and therefore this review features a general and comparative discussion of Synapsin function. Phosphorylation of Synapsin ensures an alteration of synaptic strength between this mushroom body neuron and its target neuron(s). If the trained odour is encountered again, the pattern of mushroom body neurons coding this odour is activated, such that their modified output now allows conditioned behaviour. However, such an activated memory trace does not automatically cause conditioned behaviour. Rather, in a process that remains off-line from behaviour, the larvae compare the value of the testing situation (based on gustatory input) with the value of the odour-activated memory trace (based on mushroom body output). The circuit towards appetitive conditioned behaviour is closed only if the memory trace suggests that tracking down the learned odour will lead to a place better than the current one. It is this expectation of a positive outcome that is the immediate cause of appetitive conditioned behaviour. Such conditioned search for reward corresponds to a view of aversive conditioned behaviour as conditioned escape from punishment, which is enabled only if there is something to escape from - much in the same way as we only search for things that are not there, and run for the emergency exit only when there is an emergency. One may now ask whether beyond 'value' additional information about reinforcement is contained in the memory trace, such as information about the kind and intensity of the reinforcer used. The Drosophila larva may allow us to develop satisfyingly detailed accounts of such mnemonic richness - if it exists.
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Affiliation(s)
- Sören Diegelmann
- Leibniz Institut für Neurobiologie (LIN), Abteilung Genetik von Lernen und Gedächtnis, Brenneckestrasse 6, 39118 Magdeburg, Germany
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‘Decision Making’ in Larval Drosophila. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-12-415823-8.00005-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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12
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Heo S, Csaszar E, Jung G, Beuk T, Höger H, Lubec G. Hippocampal levels and activity of the sodium/potassium transporting ATPase subunit α-3 (AT1A3) are paralleling memory training in the multiple T-maze in the C57BL/6J mouse. Neurochem Int 2012; 61:702-12. [PMID: 22797008 DOI: 10.1016/j.neuint.2012.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 07/03/2012] [Accepted: 07/04/2012] [Indexed: 12/23/2022]
Abstract
Although the sodium/potassium transporting ATPase subunit alpha-3 (AT1A3) has been linked to memory mechanisms in rodents, regulation of this ATPase in terms of activity and complex levels by memory performance in a land maze has not been shown so far. It was therefore the aim of the study to link memory retrieval in the multiple T-Maze (MTM) to AT1A3 protein levels and activity. C57BL/6J mice were trained in the MTM and euthanized 6h following memory retrieval. Hippocampal membrane proteins were prepared by ultracentrifugation and run on blue native gel electrophoresis (BN-PAGE). Enzyme activity was evaluated using an in-gel method. AT1A3 protein was characterized using mass spectrometry (nano-LC-ESI-MS/MS). On BN-PAGE a single band was observed at 240 kDa, which corresponds to the dimeric form of the enzyme. Higher levels of AT1A3 complex were seen in trained mice. Also ATPase activity was higher in trained mice, and was observed both at 110 and at 240 kDa. Mass spectrometry unambiguously identified AT1A3 with 98.91% sequence coverage. A series of novel AT1A3 phosphorylation sites were detected. Taken together, it was shown that increased AT1A3 protein levels for the dimer as well as AT1A3 activity represented by the monomer and the dimer were paralleling memory training in the MTM. This may be relevant for understanding the role of the catalytic hydrolysis of ATP coupled with the exchange of sodium and potassium ions across the plasma membrane that generates the electrochemical gradient of sodium and potassium ions. Herein, we provide evidence for a possible role of AT1A3 in memory mechanisms and support previous findings using different animal models for memory formation.
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Affiliation(s)
- Seok Heo
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Währinger Gürtel 18, A-1090 Vienna, Austria
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13
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Hippocampal glutamate transporter 1 (GLT-1) complex levels are paralleling memory training in the Multiple T-maze in C57BL/6J mice. Brain Struct Funct 2011; 217:363-78. [PMID: 22113856 DOI: 10.1007/s00429-011-0362-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 11/08/2011] [Indexed: 12/25/2022]
Abstract
The glutamate transporter 1 (GLT-1) is essential for glutamate uptake in the brain and associated with various psychiatric and neurological disorders. Pharmacological inhibition of GLT-1 results in memory deficits, but no study linking native GLT-1 complexes was published so far. It was therefore the aim of the study to associate this highly hydrophobic, eight transmembrane spanning domains containing transporter to memory training in the Multiple T-maze (MTM). C57BL/6J mice were used for the spatial memory training experiments, and trained mice were compared to untrained (yoked) animals. Mouse hippocampi were dissected out 6 h after training on day 4, and a total enriched membrane fraction was prepared by ultracentrifugation. Membrane proteins were separated by blue native polyacrylamide gel electrophoresis (BN-PAGE) with subsequent Western blotting against GLT-1 on these native gels. Moreover, GLT-1 complexes were identified by mass spectrometry (nano-LC-ESI-MS/MS). Animals learned the MTM task and multiple GLT-1 complexes were detected at apparent molecular weights of 242, 480 and 720 kDa on BN-PAGE Western blotting. GLT-1 complex levels were significantly higher in the trained group as compared to yoked controls, and antibody specificity was verified by immunoblotting on multidimensional gels. Hippocampal GLT-1 was unambiguously identified by mass spectrometry with high sequence coverage, and glycosylation was observed. It is revealed that increased GLT-1 complex levels are paralleling and are linked to spatial memory training. We provide evidence that signal termination, represented by the excitatory amino acid transporter GLT-1 complexes, is involved in spatial memory mechanisms.
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Michels B, Chen YC, Saumweber T, Mishra D, Tanimoto H, Schmid B, Engmann O, Gerber B. Cellular site and molecular mode of synapsin action in associative learning. Learn Mem 2011; 18:332-44. [PMID: 21518740 DOI: 10.1101/lm.2101411] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Synapsin is an evolutionarily conserved, presynaptic vesicular phosphoprotein. Here, we ask where and how synapsin functions in associative behavioral plasticity. Upon loss or reduction of synapsin in a deletion mutant or via RNAi, respectively, Drosophila larvae are impaired in odor-sugar associative learning. Acute global expression of synapsin and local expression in only the mushroom body, a third-order "cortical" brain region, fully restores associative ability in the mutant. No rescue is found by synapsin expression in mushroom body input neurons or by expression excluding the mushroom bodies. On the molecular level, we find that a transgenically expressed synapsin with dysfunctional PKA-consensus sites cannot rescue the defect of the mutant in associative function, thus assigning synapsin as a behaviorally relevant effector of the AC-cAMP-PKA cascade. We therefore suggest that synapsin acts in associative memory trace formation in the mushroom bodies, as a downstream element of AC-cAMP-PKA signaling. These analyses provide a comprehensive chain of explanation from the molecular level to an associative behavioral change.
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Affiliation(s)
- Birgit Michels
- Universität Würzburg, Biozentrum, Neurobiologie und Genetik, 97074 Würzburg, Germany
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