1
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Bgatova N, Obanina N, Taskaeva I, Makarova V, Rakhmetova A, Shatskaya S, Khotskin N, Zavjalov E. Accumulation and neuroprotective effects of lithium on hepatocellular carcinoma mice model. Behav Brain Res 2024; 456:114679. [PMID: 37739227 DOI: 10.1016/j.bbr.2023.114679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 09/18/2023] [Accepted: 09/19/2023] [Indexed: 09/24/2023]
Abstract
AIM The peripheral tumor growth is accompanied by the accumulation of inflammatory mediators in the blood that can negatively influence blood-brain barrier function and neuronal structure and develop the cancer-associated depression. The aim of the study was to evaluate the neurobiological effects of lithium on hepatocellular carcinoma mice model. METHODS In this study we analyzed the locomotor activity of lithium-treated tumor-bearing mice using the Phenomaster instrument. Inductively coupled plasma mass-spectral analysis was used to determine lithium levels in blood, brain, liver, kidneys, tumors and muscle tissues. The prefrontal cortex neurons ultrastructure was assessed by transmission electron microscopy. Expression of BDNF, GRP78, EEA1, LAMP1, and LC3 beta in neurons was determined by immunohistochemical analysis. RESULTS A decrease in locomotor activity was found in animals with tumors. At the same time, the low expression levels of the neurotrophic factor BDNF and early endosomal marker EEA1 were revealed, as well as the decreased amount of synaptic vesicles and synapses was shown. Signs of endoplasmic reticulum stress and autophagy development in neurons of animals with tumors were noted. Lithium carbonate administration had a corrective effect on animal's behavior and the prefrontal cortex neurons structure. CONCLUSIONS In summary, lithium can restore the neuronal homeostasis in tumor-bearing mice.
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Affiliation(s)
- Nataliya Bgatova
- Research Institute of Clinical and Experimental Lymphology - Branch of the Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Natalia Obanina
- Research Institute of Clinical and Experimental Lymphology - Branch of the Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Iuliia Taskaeva
- Research Institute of Clinical and Experimental Lymphology - Branch of the Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
| | - Viktoriia Makarova
- Research Institute of Clinical and Experimental Lymphology - Branch of the Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | | | - Svetlana Shatskaya
- Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
| | - Nikita Khotskin
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
| | - Evgenii Zavjalov
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
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2
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Stone A, Cujic O, Rowlett A, Aderhold S, Savage E, Graham B, Steinert JR. Triose-phosphate isomerase deficiency is associated with a dysregulation of synaptic vesicle recycling in Drosophila melanogaster. Front Synaptic Neurosci 2023; 15:1124061. [PMID: 36926383 PMCID: PMC10011161 DOI: 10.3389/fnsyn.2023.1124061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 02/10/2023] [Indexed: 03/08/2023] Open
Abstract
Introduction Numerous neurodegenerative diseases are associated with neuronal dysfunction caused by increased redox stress, often linked to aberrant production of redox-active molecules such as nitric oxide (NO) or oxygen free radicals. One such protein affected by redox-mediated changes is the glycolytic enzyme triose-phosphate isomerase (TPI), which has been shown to undergo 3-nitrotyrosination (a NO-mediated post-translational modification) rendering it inactive. The resulting neuronal changes caused by this modification are not well understood. However, associated glycation-induced cytotoxicity has been reported, thus potentially causing neuronal and synaptic dysfunction via compromising synaptic vesicle recycling. Methods This work uses Drosophila melanogaster to identify the impacts of altered TPI activity on neuronal physiology, linking aberrant TPI function and redox stress to neuronal defects. We used Drosophila mutants expressing a missense allele of the TPI protein, M81T, identified in a previous screen and resulting in an inactive mutant of the TPI protein (TPIM81T , wstd1). We assessed synaptic physiology at the glutamatergic Drosophila neuromuscular junction (NMJ), synapse morphology and behavioural phenotypes, as well as impacts on longevity. Results Electrophysiological recordings of evoked and spontaneous excitatory junctional currents, alongside high frequency train stimulations and recovery protocols, were applied to investigate synaptic depletion and subsequent recovery. Single synaptic currents were unaltered in the presence of the wstd1 mutation, but frequencies of spontaneous events were reduced. Wstd1 larvae also showed enhanced vesicle depletion rates at higher frequency stimulation, and subsequent recovery times for evoked synaptic responses were prolonged. A computational model showed that TPI mutant larvae exhibited a significant decline in activity-dependent vesicle recycling, which manifests itself as increased recovery times for the readily-releasable vesicle pool. Confocal images of NMJs showed no morphological or developmental differences between wild-type and wstd1 but TPI mutants exhibited learning impairments as assessed by olfactory associative learning assays. Discussion Our data suggests that the wstd1 phenotype is partially due to altered vesicle dynamics, involving a reduced vesicle pool replenishment, and altered endo/exocytosis processes. This may result in learning and memory impairments and neuronal dysfunction potentially also presenting a contributing factor to other reported neuronal phenotypes.
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Affiliation(s)
- Aelfwin Stone
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Oliver Cujic
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Angel Rowlett
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Sophia Aderhold
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Emma Savage
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Bruce Graham
- Division of Computing Science and Mathematics, Faculty of Natural Sciences, University of Stirling, Stirling, United Kingdom
| | - Joern R Steinert
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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3
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Peng YJ, Geng J, Wu Y, Pinales C, Langen J, Chang YC, Buser C, Chang KT. Minibrain kinase and calcineurin coordinate activity-dependent bulk endocytosis through synaptojanin. J Cell Biol 2021; 220:212674. [PMID: 34596663 PMCID: PMC8491876 DOI: 10.1083/jcb.202011028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 07/28/2021] [Accepted: 09/16/2021] [Indexed: 11/22/2022] Open
Abstract
Neurons use multiple modes of endocytosis, including clathrin-mediated endocytosis (CME) and activity-dependent bulk endocytosis (ADBE), during mild and intense neuronal activity, respectively, to maintain stable neurotransmission. While molecular players modulating CME are well characterized, factors regulating ADBE and mechanisms coordinating CME and ADBE activations remain poorly understood. Here we report that Minibrain/DYRK1A (Mnb), a kinase mutated in autism and up-regulated in Down's syndrome, plays a novel role in suppressing ADBE. We demonstrate that Mnb, together with calcineurin, delicately coordinates CME and ADBE by controlling the phosphoinositol phosphatase activity of synaptojanin (Synj) during varying synaptic demands. Functional domain analyses reveal that Synj's 5'-phosphoinositol phosphatase activity suppresses ADBE, while SAC1 activity is required for efficient ADBE. Consequently, Parkinson's disease mutation in Synj's SAC1 domain impairs ADBE. These data identify Mnb and Synj as novel regulators of ADBE and further indicate that CME and ADBE are differentially governed by Synj's dual phosphatase domains.
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Affiliation(s)
- Yi-Jheng Peng
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA.,Neuroscience Graduate Program, University of Southern California, Los Angeles, CA
| | - Junhua Geng
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Ying Wu
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | | | - Jennifer Langen
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Yen-Ching Chang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | | | - Karen T Chang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA.,Neuroscience Graduate Program, University of Southern California, Los Angeles, CA.,Department of Physiology & Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA
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4
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Giménez-Palomo A, Dodd S, Anmella G, Carvalho AF, Scaini G, Quevedo J, Pacchiarotti I, Vieta E, Berk M. The Role of Mitochondria in Mood Disorders: From Physiology to Pathophysiology and to Treatment. Front Psychiatry 2021; 12:546801. [PMID: 34295268 PMCID: PMC8291901 DOI: 10.3389/fpsyt.2021.546801] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 05/24/2021] [Indexed: 12/30/2022] Open
Abstract
Mitochondria are cellular organelles involved in several biological processes, especially in energy production. Several studies have found a relationship between mitochondrial dysfunction and mood disorders, such as major depressive disorder and bipolar disorder. Impairments in energy production are found in these disorders together with higher levels of oxidative stress. Recently, many agents capable of enhancing antioxidant defenses or mitochondrial functioning have been studied for the treatment of mood disorders as adjuvant therapy to current pharmacological treatments. A better knowledge of mitochondrial physiology and pathophysiology might allow the identification of new therapeutic targets and the development and study of novel effective therapies to treat these specific mitochondrial impairments. This could be especially beneficial for treatment-resistant patients. In this article, we provide a focused narrative review of the currently available evidence supporting the involvement of mitochondrial dysfunction in mood disorders, the effects of current therapies on mitochondrial functions, and novel targeted therapies acting on mitochondrial pathways that might be useful for the treatment of mood disorders.
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Affiliation(s)
- Anna Giménez-Palomo
- Bipolar and Depressives Disorders Unit, Hospital Clínic, University of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Mental Health Research Networking Center (CIBERSAM), Madrid, Spain
| | - Seetal Dodd
- Deakin University, The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, VIC, Australia.,Department of Psychiatry, Centre for Youth Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Gerard Anmella
- Bipolar and Depressives Disorders Unit, Hospital Clínic, University of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Mental Health Research Networking Center (CIBERSAM), Madrid, Spain
| | - Andre F Carvalho
- Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Giselli Scaini
- Translational Psychiatry Program, Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Joao Quevedo
- Translational Psychiatry Program, Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States.,Neuroscience Graduate Program, The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States.,Translational Psychiatry Laboratory, Graduate Program in Health Sciences, University of Southern Santa Catarina, Criciúma, Brazil.,Center of Excellence in Mood Disorders, Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Isabella Pacchiarotti
- Bipolar and Depressives Disorders Unit, Hospital Clínic, University of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Mental Health Research Networking Center (CIBERSAM), Madrid, Spain
| | - Eduard Vieta
- Bipolar and Depressives Disorders Unit, Hospital Clínic, University of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Mental Health Research Networking Center (CIBERSAM), Madrid, Spain
| | - Michael Berk
- School of Medicine, The Institute for Mental and Physical Health and Clinical Translation, Deakin University, Barwon Health, Geelong, VIC, Australia.,Orygen, The National Centre of Excellence in Youth Mental Health, Parkville, VIC, Australia.,Centre for Youth Mental Health, Florey Institute for Neuroscience and Mental Health and the Department of Psychiatry, The University of Melbourne, Melbourne, VIC, Australia
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5
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Pensold D, Reichard J, Van Loo KMJ, Ciganok N, Hahn A, Bayer C, Liebmann L, Groß J, Tittelmeier J, Lingner T, Salinas-Riester G, Symmank J, Halfmann C, González-Bermúdez L, Urbach A, Gehrmann J, Costa I, Pieler T, Hübner CA, Vatter H, Kampa B, Becker AJ, Zimmer-Bensch G. DNA Methylation-Mediated Modulation of Endocytosis as Potential Mechanism for Synaptic Function Regulation in Murine Inhibitory Cortical Interneurons. Cereb Cortex 2020; 30:3921-3937. [PMID: 32147726 PMCID: PMC7264686 DOI: 10.1093/cercor/bhaa009] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/14/2019] [Accepted: 01/10/2020] [Indexed: 12/25/2022] Open
Abstract
The balance of excitation and inhibition is essential for cortical information processing, relying on the tight orchestration of the underlying subcellular processes. Dynamic transcriptional control by DNA methylation, catalyzed by DNA methyltransferases (DNMTs), and DNA demethylation, achieved by ten–eleven translocation (TET)-dependent mechanisms, is proposed to regulate synaptic function in the adult brain with implications for learning and memory. However, focus so far is laid on excitatory neurons. Given the crucial role of inhibitory cortical interneurons in cortical information processing and in disease, deciphering the cellular and molecular mechanisms of GABAergic transmission is fundamental. The emerging relevance of DNMT and TET-mediated functions for synaptic regulation irrevocably raises the question for the targeted subcellular processes and mechanisms. In this study, we analyzed the role dynamic DNA methylation has in regulating cortical interneuron function. We found that DNMT1 and TET1/TET3 contrarily modulate clathrin-mediated endocytosis. Moreover, we provide evidence that DNMT1 influences synaptic vesicle replenishment and GABAergic transmission, presumably through the DNA methylation-dependent transcriptional control over endocytosis-related genes. The relevance of our findings is supported by human brain sample analysis, pointing to a potential implication of DNA methylation-dependent endocytosis regulation in the pathophysiology of temporal lobe epilepsy, a disease characterized by disturbed synaptic transmission.
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Affiliation(s)
- Daniel Pensold
- Institute of Human Genetics, University Hospital Jena, 07743 Jena, Germany.,Division of Functional Epigenetics, Institute of Zoology (Biology 2), RWTH Aachen University, 52074 Aachen, Germany
| | - Julia Reichard
- Institute of Human Genetics, University Hospital Jena, 07743 Jena, Germany.,Division of Functional Epigenetics, Institute of Zoology (Biology 2), RWTH Aachen University, 52074 Aachen, Germany.,Research Training Group 2416 Multi Senses-Multi Scales, RWTH Aachen University, 52074 Aachen, Germany
| | - Karen M J Van Loo
- Department of Neuropathology, Section for Translational Epilepsy Research, University of Bonn Medical Center, 53105 Bonn, Germany
| | - Natalja Ciganok
- Division of Systems Neurophysiology, Institute of Zoology (Biology 2), RWTH Aachen University, 52074 Aachen, Germany
| | - Anne Hahn
- Institute of Human Genetics, University Hospital Jena, 07743 Jena, Germany
| | - Cathrin Bayer
- Institute of Human Genetics, University Hospital Jena, 07743 Jena, Germany.,Division of Functional Epigenetics, Institute of Zoology (Biology 2), RWTH Aachen University, 52074 Aachen, Germany
| | - Lutz Liebmann
- Institute of Human Genetics, University Hospital Jena, 07743 Jena, Germany
| | - Jonas Groß
- Institute of Human Genetics, University Hospital Jena, 07743 Jena, Germany
| | | | - Thomas Lingner
- Department of Developmental Biochemistry, Transcriptome and Genome Analysis Laboratory (TAL), University of Goettingen, 37077 Goettingen, Germany
| | - Gabriela Salinas-Riester
- Department of Developmental Biochemistry, Transcriptome and Genome Analysis Laboratory (TAL), University of Goettingen, 37077 Goettingen, Germany
| | - Judit Symmank
- Institute of Human Genetics, University Hospital Jena, 07743 Jena, Germany
| | - Claas Halfmann
- Division of Systems Neurophysiology, Institute of Zoology (Biology 2), RWTH Aachen University, 52074 Aachen, Germany
| | | | - Anja Urbach
- Clinic for Neurology, University Hospital Jena, 07743 Jena, Germany
| | - Julia Gehrmann
- Institute for Computational Genomics, University Hospital Aachen, RWTH Aachen University, 52074 Aachen, Germany
| | - Ivan Costa
- Institute for Computational Genomics, University Hospital Aachen, RWTH Aachen University, 52074 Aachen, Germany
| | - Tomas Pieler
- Department of Developmental Biochemistry, Centre for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), University of Goettingen, 37077 Goettingen, Germany
| | - Christian A Hübner
- Institute of Human Genetics, University Hospital Jena, 07743 Jena, Germany
| | - Hartmut Vatter
- Clinic for Neurosurgery, University of Bonn Medical Center, 53105 Bonn, Germany
| | - Björn Kampa
- Division of Systems Neurophysiology, Institute of Zoology (Biology 2), RWTH Aachen University, 52074 Aachen, Germany.,JARA BRAIN, Institute for Neuroscience and Medicine, Forschungszentrum Jülich, 52425, Germany
| | - Albert J Becker
- Department of Neuropathology, Section for Translational Epilepsy Research, University of Bonn Medical Center, 53105 Bonn, Germany
| | - Geraldine Zimmer-Bensch
- Institute of Human Genetics, University Hospital Jena, 07743 Jena, Germany.,Division of Functional Epigenetics, Institute of Zoology (Biology 2), RWTH Aachen University, 52074 Aachen, Germany.,Research Training Group 2416 Multi Senses-Multi Scales, RWTH Aachen University, 52074 Aachen, Germany
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6
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Latcheva NK, Delaney TL, Viveiros JM, Smith RA, Bernard KM, Harsin B, Marenda DR, Liebl FLW. The CHD Protein, Kismet, is Important for the Recycling of Synaptic Vesicles during Endocytosis. Sci Rep 2019; 9:19368. [PMID: 31852969 PMCID: PMC6920434 DOI: 10.1038/s41598-019-55900-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 11/29/2019] [Indexed: 12/14/2022] Open
Abstract
Chromatin remodeling proteins of the chromodomain DNA-binding protein family, CHD7 and CHD8, mediate early neurodevelopmental events including neural migration and differentiation. As such, mutations in either protein can lead to neurodevelopmental disorders. How chromatin remodeling proteins influence the activity of mature synapses, however, is relatively unexplored. A critical feature of mature neurons is well-regulated endocytosis, which is vital for synaptic function to recycle membrane and synaptic proteins enabling the continued release of synaptic vesicles. Here we show that Kismet, the Drosophila homolog of CHD7 and CHD8, regulates endocytosis. Kismet positively influenced transcript levels and bound to dap160 and endophilin B transcription start sites and promoters in whole nervous systems and influenced the synaptic localization of Dynamin/Shibire. In addition, kismet mutants exhibit reduced VGLUT, a synaptic vesicle marker, at stimulated but not resting synapses and reduced levels of synaptic Rab11. Endocytosis is restored at kismet mutant synapses by pharmacologically inhibiting the function of histone deacetyltransferases (HDACs). These data suggest that HDAC activity may oppose Kismet to promote synaptic vesicle endocytosis. A deeper understanding of how CHD proteins regulate the function of mature neurons will help better understand neurodevelopmental disorders.
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Affiliation(s)
- Nina K Latcheva
- Department of Biology, Drexel University, 3141 Chestnut St., Philadelphia, PA, 19104, USA.,Program in Molecular and Cellular Biology and Genetics, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Taylor L Delaney
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA
| | - Jennifer M Viveiros
- Department of Biology, Drexel University, 3141 Chestnut St., Philadelphia, PA, 19104, USA
| | - Rachel A Smith
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA
| | - Kelsey M Bernard
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA
| | - Benjamin Harsin
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA
| | - Daniel R Marenda
- Department of Biology, Drexel University, 3141 Chestnut St., Philadelphia, PA, 19104, USA.,Program in Molecular and Cellular Biology and Genetics, Drexel University College of Medicine, Philadelphia, PA, USA.,Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Faith L W Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA.
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7
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Manzo E, Lorenzini I, Barrameda D, O'Conner AG, Barrows JM, Starr A, Kovalik T, Rabichow BE, Lehmkuhl EM, Shreiner DD, Joardar A, Liévens JC, Bowser R, Sattler R, Zarnescu DC. Glycolysis upregulation is neuroprotective as a compensatory mechanism in ALS. eLife 2019; 8:45114. [PMID: 31180318 PMCID: PMC6557627 DOI: 10.7554/elife.45114] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 05/20/2019] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS), is a fatal neurodegenerative disorder, with TDP-43 inclusions as a major pathological hallmark. Using a Drosophila model of TDP-43 proteinopathy we found significant alterations in glucose metabolism including increased pyruvate, suggesting that modulating glycolysis may be neuroprotective. Indeed, a high sugar diet improves locomotor and lifespan defects caused by TDP-43 proteinopathy in motor neurons or glia, but not muscle, suggesting that metabolic dysregulation occurs in the nervous system. Overexpressing human glucose transporter GLUT-3 in motor neurons mitigates TDP-43 dependent defects in synaptic vesicle recycling and improves locomotion. Furthermore, PFK mRNA, a key indicator of glycolysis, is upregulated in flies and patient derived iPSC motor neurons with TDP-43 pathology. Surprisingly, PFK overexpression rescues TDP-43 induced locomotor deficits. These findings from multiple ALS models show that mechanistically, glycolysis is upregulated in degenerating motor neurons as a compensatory mechanism and suggest that increased glucose availability is protective.
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Affiliation(s)
- Ernesto Manzo
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Ileana Lorenzini
- Department of Neurology, Barrow Neurological Institute, Phoenix, United States
| | - Dianne Barrameda
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Abigail G O'Conner
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Jordan M Barrows
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Alexander Starr
- Department of Neurology, Barrow Neurological Institute, Phoenix, United States
| | - Tina Kovalik
- Department of Neurology, Barrow Neurological Institute, Phoenix, United States
| | - Benjamin E Rabichow
- Department of Neurology, Barrow Neurological Institute, Phoenix, United States
| | - Erik M Lehmkuhl
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Dakotah D Shreiner
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Archi Joardar
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | | | - Robert Bowser
- Department of Neurology, Barrow Neurological Institute, Phoenix, United States
| | - Rita Sattler
- Department of Neurology, Barrow Neurological Institute, Phoenix, United States
| | - Daniela C Zarnescu
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States.,Department of Neuroscience, University of Arizona, Tucson, United States.,Department of Neurobiology, University of Arizona, Tucson, United States
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8
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Coyne AN, Lorenzini I, Chou CC, Torvund M, Rogers RS, Starr A, Zaepfel BL, Levy J, Johannesmeyer J, Schwartz JC, Nishimune H, Zinsmaier K, Rossoll W, Sattler R, Zarnescu DC. Post-transcriptional Inhibition of Hsc70-4/HSPA8 Expression Leads to Synaptic Vesicle Cycling Defects in Multiple Models of ALS. Cell Rep 2018; 21:110-125. [PMID: 28978466 DOI: 10.1016/j.celrep.2017.09.028] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 05/09/2017] [Accepted: 09/07/2017] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a synaptopathy accompanied by the presence of cytoplasmic aggregates containing TDP-43, an RNA-binding protein linked to ∼97% of ALS cases. Using a Drosophila model of ALS, we show that TDP-43 overexpression (OE) in motor neurons results in decreased expression of the Hsc70-4 chaperone at the neuromuscular junction (NMJ). Mechanistically, mutant TDP-43 sequesters hsc70-4 mRNA and impairs its translation. Expression of the Hsc70-4 ortholog, HSPA8, is also reduced in primary motor neurons and NMJs of mice expressing mutant TDP-43. Electrophysiology, imaging, and genetic interaction experiments reveal TDP-43-dependent defects in synaptic vesicle endocytosis. These deficits can be partially restored by OE of Hsc70-4, cysteine-string protein (Csp), or dynamin. This suggests that TDP-43 toxicity results in part from impaired activity of the synaptic CSP/Hsc70 chaperone complex impacting dynamin function. Finally, Hsc70-4/HSPA8 expression is also post-transcriptionally reduced in fly and human induced pluripotent stem cell (iPSC) C9orf72 models, suggesting a common disease pathomechanism.
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Affiliation(s)
- Alyssa N Coyne
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA; Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA
| | - Ileana Lorenzini
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
| | - Ching-Chieh Chou
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Meaghan Torvund
- Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA
| | - Robert S Rogers
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS 66160, USA
| | - Alexander Starr
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
| | - Benjamin L Zaepfel
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Jennifer Levy
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
| | - Jeffrey Johannesmeyer
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Jacob C Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS 66160, USA
| | - Konrad Zinsmaier
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA; Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA
| | - Wilfried Rossoll
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Rita Sattler
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
| | - Daniela C Zarnescu
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA; Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA; Department of Neurology, University of Arizona, Tucson, AZ 85721, USA.
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9
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Robinson SW, Bourgognon JM, Spiers JG, Breda C, Campesan S, Butcher A, Mallucci GR, Dinsdale D, Morone N, Mistry R, Smith TM, Guerra-Martin M, Challiss RAJ, Giorgini F, Steinert JR. Nitric oxide-mediated posttranslational modifications control neurotransmitter release by modulating complexin farnesylation and enhancing its clamping ability. PLoS Biol 2018; 16:e2003611. [PMID: 29630591 PMCID: PMC5890968 DOI: 10.1371/journal.pbio.2003611] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 02/20/2018] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO) regulates neuronal function and thus is critical for tuning neuronal communication. Mechanisms by which NO modulates protein function and interaction include posttranslational modifications (PTMs) such as S-nitrosylation. Importantly, cross signaling between S-nitrosylation and prenylation can have major regulatory potential. However, the exact protein targets and resulting changes in function remain elusive. Here, we interrogated the role of NO-dependent PTMs and farnesylation in synaptic transmission. We found that NO compromises synaptic function at the Drosophila neuromuscular junction (NMJ) in a cGMP-independent manner. NO suppressed release and reduced the size of available vesicle pools, which was reversed by glutathione (GSH) and occluded by genetic up-regulation of GSH-generating and de-nitrosylating glutamate-cysteine-ligase and S-nitroso-glutathione reductase activities. Enhanced nitrergic activity led to S-nitrosylation of the fusion-clamp protein complexin (cpx) and altered its membrane association and interactions with active zone (AZ) and soluble N-ethyl-maleimide-sensitive fusion protein Attachment Protein Receptor (SNARE) proteins. Furthermore, genetic and pharmacological suppression of farnesylation and a nitrosylation mimetic mutant of cpx induced identical physiological and localization phenotypes as caused by NO. Together, our data provide evidence for a novel physiological nitrergic molecular switch involving S-nitrosylation, which reversibly suppresses farnesylation and thereby enhances the net-clamping function of cpx. These data illustrate a new mechanistic signaling pathway by which regulation of farnesylation can fine-tune synaptic release.
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Affiliation(s)
- Susan W. Robinson
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | | | - Jereme G. Spiers
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Carlo Breda
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Susanna Campesan
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Adrian Butcher
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Giovanna R. Mallucci
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - David Dinsdale
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Nobuhiro Morone
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Raj Mistry
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Tim M. Smith
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | | | - R. A. John Challiss
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Flaviano Giorgini
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Joern R. Steinert
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- * E-mail:
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10
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Ehmann N, Owald D, Kittel RJ. Drosophila active zones: From molecules to behaviour. Neurosci Res 2018; 127:14-24. [DOI: 10.1016/j.neures.2017.11.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 11/30/2017] [Accepted: 11/30/2017] [Indexed: 11/15/2022]
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11
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Phosphorylation of Synaptojanin Differentially Regulates Endocytosis of Functionally Distinct Synaptic Vesicle Pools. J Neurosci 2017; 36:8882-94. [PMID: 27559170 DOI: 10.1523/jneurosci.1470-16.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/14/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED The rapid replenishment of synaptic vesicles through endocytosis is crucial for sustaining synaptic transmission during intense neuronal activity. Synaptojanin (Synj), a phosphoinositide phosphatase, is known to play an important role in vesicle recycling by promoting the uncoating of clathrin following synaptic vesicle uptake. Synj has been shown to be a substrate of the minibrain (Mnb) kinase, a fly homolog of the dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A); however, the functional impacts of Synj phosphorylation by Mnb are not well understood. Here we identify that Mnb phosphorylates Synj at S1029 in Drosophila We find that phosphorylation of Synj at S1029 enhances Synj phosphatase activity, alters interaction between Synj and endophilin, and promotes efficient endocytosis of the active cycling vesicle pool (also referred to as exo-endo cycling pool) at the expense of reserve pool vesicle endocytosis. Dephosphorylated Synj, on the other hand, is deficient in the endocytosis of the active recycling pool vesicles but maintains reserve pool vesicle endocytosis to restore total vesicle pool size and sustain synaptic transmission. Together, our findings reveal a novel role for Synj in modulating reserve pool vesicle endocytosis and further indicate that dynamic phosphorylation and dephosphorylation of Synj differentially maintain endocytosis of distinct functional synaptic vesicle pools. SIGNIFICANCE STATEMENT Synaptic vesicle endocytosis sustains communication between neurons during a wide range of neuronal activities by recycling used vesicle membrane and protein components. Here we identify that Synaptojanin, a protein with a known role in synaptic vesicle endocytosis, is phosphorylated at S1029 in vivo by the Minibrain kinase. We further demonstrate that the phosphorylation status of Synaptojanin at S1029 differentially regulates its participation in the recycling of distinct synaptic vesicle pools. Our results reveal a new role for Synaptojanin in maintaining synaptic vesicle pool size and in reserve vesicle endocytosis. As Synaptojanin and Minibrain perturbations are associated with various neurological disorders, such as Parkinson's, autism, and Down syndrome, understanding mechanisms modulating Synaptojanin function provides valuable insights into processes affecting neuronal communication.
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Locomotion Behavior Is Affected by the Gα S Pathway and the Two-Pore-Domain K + Channel TWK-7 Interacting in GABAergic Motor Neurons in Caenorhabditis elegans. Genetics 2017; 206:283-297. [PMID: 28341653 DOI: 10.1534/genetics.116.195669] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 03/19/2017] [Indexed: 01/03/2023] Open
Abstract
Adjusting the efficiency of movement in response to environmental cues is an essential integrative characteristic of adaptive locomotion behavior across species. However, the modulatory molecules and the pathways involved are largely unknown. Recently, we demonstrated that in Caenorhabditis elegans, a loss-of-function of the two-pore-domain potassium (K2P) channel TWK-7 causes a fast, coordinated, and persistent forward crawling behavior in which five central aspects of stimulated locomotion-velocity, direction, wave parameters, duration, and straightness-are affected. Here, we isolated the reduction-of-function allele cau1 of the C. elegans gene kin-2 in a forward genetic screen and showed that it phenocopies the locomotor activity and locomotion behavior of twk-7(null) animals. Kin-2 encodes the negative regulatory subunit of protein kinase A (KIN-1/PKA). Consistently, we found that other gain-of-function mutants of the GαS-KIN-1/PKA pathway resemble kin-2(cau1) and twk-7(null) in locomotion phenotype. Using the powerful genetics of the C. elegans system in combination with cell type-specific approaches and detailed locomotion analyses, we identified TWK-7 as a putative downstream target of the GαS-KIN-1/PKA pathway at the level of the γ-aminobutyric acid (GABA)ergic D-type motor neurons. Due to this epistatic interaction, we suggest that KIN-1/PKA and TWK-7 may share a common pathway that is probably involved in the modulation of both locomotor activity and locomotion behavior during forward crawling.
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Bansal Y, Kuhad A. Mitochondrial Dysfunction in Depression. Curr Neuropharmacol 2017; 14:610-8. [PMID: 26923778 PMCID: PMC4981740 DOI: 10.2174/1570159x14666160229114755] [Citation(s) in RCA: 205] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Revised: 06/02/2015] [Accepted: 02/27/2016] [Indexed: 02/06/2023] Open
Abstract
Abstract: Background Depression is the most debilitating neuropsychiatric disorder with significant impact on socio-occupational and well being of individual. The exact pathophysiology of depression is still enigmatic though various theories have been put forwarded. There are evidences showing that mitochondrial dysfunction in various brain regions is associated with depression. Recent findings have sparked renewed appreciation for the role of mitochondria in many intracellular processes coupled to synaptic plasticity and cellular resilience. New insights in depression pathophysiology are revolving around the impairment of neuroplasticity. Mitochondria have potential role in ATP production, intracellular Ca2+ signalling to establish membrane stability, reactive oxygen species (ROS) balance and to execute the complex processes of neurotransmission and plasticity. So understanding the various concepts of mitochondrial dysfunction in pathogenesis of depression indubitably helps to generate novel and more targeted therapeutic approaches for depression treatment. Objective The review was aimed to give a comprehensive insight on role of mitochondrial dysfunction in depression. Result Targeting mitochondrial dysfunction and enhancing the mitochondrial functions might act as potential target for the treatment of depression. Conclusion Literature cited in this review highly supports the role of mitochondrial dysfunction in depression. As impairment in the mitochondrial functions lead to the generation of various insults that exaggerate the pathogenesis of depression. So, it is useful to study mitochondrial dysfunction in relation to mood disorders, synaptic plasticity, neurogenesis and enhancing the functions of mitochondria might show promiscuous effects in the treatment of depressed patients.
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Affiliation(s)
| | - Anurag Kuhad
- Pharmacology Research Laboratory, University Institute of Pharmaceutical Sciences UGC-Centre of Advanced Study, Panjab University, Chandigarh - 160 014 India.
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14
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Rossano AJ, Kato A, Minard KI, Romero MF, Macleod GT. Na + /H + exchange via the Drosophila vesicular glutamate transporter mediates activity-induced acid efflux from presynaptic terminals. J Physiol 2016; 595:805-824. [PMID: 27641622 DOI: 10.1113/jp273105] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 09/14/2016] [Indexed: 01/26/2023] Open
Abstract
KEY POINTS Intracellular pH regulation is vital to neurons as nerve activity produces large and rapid acid loads in presynaptic terminals. Rapid clearance of acid loads is necessary to maintain control of neurotransmission, but neuronal acid clearance mechanisms remain poorly understood. Glutamate is loaded into synaptic vesicles via the vesicular glutamate transporter (VGLUT), a mechanism conserved across phyla, and this study reports a previously unknown role for VGLUT as an acid-extruding protein when deposited in the plasmamembrane during exocytosis. The finding was made in Drosophila (fruit fly) larval motor neurons through a combined pharamacological and genetic dissection of presynaptic pH homeostatic mechanisms. A dual role for VGLUT serves to integrate neuronal activity and pH regulation in presynaptic nerve terminals. ABSTRACT Neuronal activity can result in transient acidification of presynaptic terminals, and such shifts in cytosolic pH (pHcyto ) probably influence mechanisms underlying forms of synaptic plasticity with a presynaptic locus. As neuronal activity drives acid loading in presynaptic terminals, we hypothesized that the same activity might drive acid efflux mechanisms to maintain pHcyto homeostasis. To better understand the integration of neuronal activity and pHcyto regulation we investigated the acid extrusion mechanisms at Drosophila glutamatergic motorneuron terminals. Expression of a fluorescent genetically encoded pH indicator, named 'pHerry', in the presynaptic cytosol revealed acid efflux following nerve activity to be greater than that predicted from measurements of the intrinsic rate of acid efflux. Analysis of activity-induced acid transients in terminals deficient in either endocytosis or exocytosis revealed an acid efflux mechanism reliant upon synaptic vesicle exocytosis. Pharmacological and genetic dissection in situ and in a heterologous expression system indicate that this acid efflux is mediated by conventional plasmamembrane acid transporters, and also by previously unrecognized intrinsic H+ /Na+ exchange via the Drosophila vesicular glutamate transporter (DVGLUT). DVGLUT functions not only as a vesicular glutamate transporter but also serves as an acid-extruding protein when deposited on the plasmamembrane.
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Affiliation(s)
- Adam J Rossano
- School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Akira Kato
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, 226-8503, Japan.,Physiology & Biomedical Engineering and Nephrology & Hypertension, Mayo Clinic College of Medicine, Rochester, MN, 55905, USA
| | - Karyl I Minard
- Biological Sciences & Wilkes Honors College, Florida Atlantic University, Jupiter, FL, 33431, USA
| | - Michael F Romero
- Physiology & Biomedical Engineering and Nephrology & Hypertension, Mayo Clinic College of Medicine, Rochester, MN, 55905, USA
| | - Gregory T Macleod
- Biological Sciences & Wilkes Honors College, Florida Atlantic University, Jupiter, FL, 33431, USA
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15
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Slater CR. The functional organization of motor nerve terminals. Prog Neurobiol 2015; 134:55-103. [DOI: 10.1016/j.pneurobio.2015.09.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 08/28/2015] [Accepted: 09/05/2015] [Indexed: 12/19/2022]
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16
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Du H, Guo L, Wu X, Sosunov AA, McKhann GM, Chen JX, Yan SS. Cyclophilin D deficiency rescues Aβ-impaired PKA/CREB signaling and alleviates synaptic degeneration. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1842:2517-27. [PMID: 23507145 PMCID: PMC3868643 DOI: 10.1016/j.bbadis.2013.03.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 02/14/2013] [Accepted: 03/08/2013] [Indexed: 12/14/2022]
Abstract
The coexistence of neuronal mitochondrial pathology and synaptic dysfunction is an early pathological feature of Alzheimer's disease (AD). Cyclophilin D (CypD), an integral part of mitochondrial permeability transition pore (mPTP), is involved in amyloid beta (Aβ)-instigated mitochondrial dysfunction. Blockade of CypD prevents Aβ-induced mitochondrial malfunction and the consequent cognitive impairments. Here, we showed the elimination of reactive oxygen species (ROS) by antioxidants probucol or superoxide dismutase (SOD)/catalase blocks Aβ-mediated inactivation of protein kinase A (PKA)/cAMP regulatory-element-binding (CREB) signal transduction pathway and loss of synapse, suggesting the detrimental effects of oxidative stress on neuronal PKA/CREB activity. Notably, neurons lacking CypD significantly attenuate Aβ-induced ROS. Consequently, CypD-deficient neurons are resistant to Aβ-disrupted PKA/CREB signaling by increased PKA activity, phosphorylation of PKA catalytic subunit (PKA C), and CREB. In parallel, lack of CypD protects neurons from Aβ-induced loss of synapses and synaptic dysfunction. Furthermore, compared to the mAPP mice, CypD-deficient mAPP mice reveal less inactivation of PKA-CREB activity and increased synaptic density, attenuate abnormalities in dendritic spine maturation, and improve spontaneous synaptic activity. These findings provide new insights into a mechanism in the crosstalk between the CypD-dependent mitochondrial oxidative stress and signaling cascade, leading to synaptic injury, functioning through the PKA/CREB signal transduction pathway.
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Affiliation(s)
- Heng Du
- Department of Pharmacology and Toxicology, and Higuchi Bioscience Center, School of Pharmacy, University of Kansas, Lawrence, KS 66047, USA
| | - Lan Guo
- Department of Pharmacology and Toxicology, and Higuchi Bioscience Center, School of Pharmacy, University of Kansas, Lawrence, KS 66047, USA
| | - Xiaoping Wu
- Department of Neurosurgery, Physicians & Surgeons College of Columbia University, New York, NY 10032, USA
| | - Alexander A Sosunov
- Department of Neurosurgery, Physicians & Surgeons College of Columbia University, New York, NY 10032, USA
| | - Guy M McKhann
- Department of Neurosurgery, Physicians & Surgeons College of Columbia University, New York, NY 10032, USA
| | - John Xi Chen
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY 1003, USA
| | - Shirley ShiDu Yan
- Department of Pharmacology and Toxicology, and Higuchi Bioscience Center, School of Pharmacy, University of Kansas, Lawrence, KS 66047, USA.
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Crimpy enables discrimination of presynaptic and postsynaptic pools of a BMP at the Drosophila neuromuscular junction. Dev Cell 2014; 31:586-98. [PMID: 25453556 DOI: 10.1016/j.devcel.2014.10.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 09/07/2014] [Accepted: 10/03/2014] [Indexed: 01/22/2023]
Abstract
Distinct pools of the bone morphogenetic protein (BMP) Glass bottom boat (Gbb) control structure and function of the Drosophila neuromuscular junction. Specifically, motoneuron-derived Gbb regulates baseline neurotransmitter release, whereas muscle-derived Gbb regulates neuromuscular junction growth. Yet how cells differentiate between these ligand pools is not known. Here we present evidence that the neuronal Gbb-binding protein Crimpy (Cmpy) permits discrimination of pre- and postsynaptic ligand by serving sequential functions in Gbb signaling. Cmpy first delivers Gbb to dense core vesicles (DCVs) for activity-dependent release from presynaptic terminals. In the absence of Cmpy, Gbb is no longer associated with DCVs and is not released by activity. Electrophysiological analyses demonstrate that Cmpy promotes Gbb's proneurotransmission function. Surprisingly, the Cmpy ectodomain is itself released upon DCV exocytosis, arguing that Cmpy serves a second function in BMP signaling. In addition to trafficking Gbb to DCVs, we propose that Gbb/Cmpy corelease from presynaptic terminals defines a neuronal protransmission signal.
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Santos MS, Foss SM, Park CK, Voglmaier SM. Protein interactions of the vesicular glutamate transporter VGLUT1. PLoS One 2014; 9:e109824. [PMID: 25334008 PMCID: PMC4198130 DOI: 10.1371/journal.pone.0109824] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 09/08/2014] [Indexed: 11/18/2022] Open
Abstract
Exocytotic release of glutamate depends upon loading of the neurotransmitter into synaptic vesicles by vesicular glutamate transporters, VGLUTs. The major isoforms, VGLUT1 and 2, exhibit a complementary pattern of expression in synapses of the adult rodent brain that correlates with the probability of release and potential for plasticity. Indeed, expression of different VGLUT protein isoforms confers different properties of release probability. Expression of VGLUT1 or 2 protein also determines the kinetics of synaptic vesicle recycling. To identify molecular determinants that may be related to reported differences in VGLUT trafficking and glutamate release properties, we investigated some of the intrinsic differences between the two isoforms. VGLUT1 and 2 exhibit a high degree of sequence homology, but differ in their N- and C-termini. While the C-termini of VGLUT1 and 2 share a dileucine-like trafficking motif and a proline-, glutamate-, serine-, and threonine-rich PEST domain, only VGLUT1 contains two polyproline domains and a phosphorylation consensus sequence in a region of acidic amino acids. The interaction of a VGLUT1 polyproline domain with the endocytic protein endophilin recruits VGLUT1 to a fast recycling pathway. To identify trans-acting cellular proteins that interact with the distinct motifs found in the C-terminus of VGLUT1, we performed a series of in vitro biochemical screening assays using the region encompassing the polyproline motifs, phosphorylation consensus sites, and PEST domain. We identify interactors that belong to several classes of proteins that modulate cellular function, including actin cytoskeletal adaptors, ubiquitin ligases, and tyrosine kinases. The nature of these interactions suggests novel avenues to investigate the modulation of synaptic vesicle protein recycling.
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Affiliation(s)
- Magda S. Santos
- Department of Psychiatry, University of California San Francisco, School of Medicine, San Francisco, California, United States of America
| | - Sarah M. Foss
- Department of Psychiatry, University of California San Francisco, School of Medicine, San Francisco, California, United States of America
- Graduate Program in Cell Biology, University of California San Francisco, School of Medicine, San Francisco, California, United States of America
| | - C. Kevin Park
- Department of Psychiatry, University of California San Francisco, School of Medicine, San Francisco, California, United States of America
| | - Susan M. Voglmaier
- Department of Psychiatry, University of California San Francisco, School of Medicine, San Francisco, California, United States of America
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Kuromi H. [My research life: from synaptic transmission to behavior]. YAKUGAKU ZASSHI 2014; 134:851-66. [PMID: 25088317 DOI: 10.1248/yakushi.14-00151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
I have studied signal transmission at synapses and the effects of drugs on it at the molecular and cellular levels. Specific areas of research interest are outlined here. 1) Electrophysiological experiments in cats and rabbits suggested that a new type of analgesic, the phenothiazine derivative levomepromazine, exerts analgesic effects by depressing emotional responses accompanying the sensation of pain. 2) It was hypothesized that motoneurons had long-term effects on muscle cell membrane properties, in addition to controlling moment-to-moment activities. The substance to recover the post-denervation changes in muscle properties in culture was partially purified from mouse nerve extract, which suggested that trophic influences were exerted by substances released from motoneurons. 3) Muscles innervated by adrenergic fibers had sites responsive to acetylcholine as well as to adrenaline in early life in chicks, but only the adrenaline-responsive sites remained during development. Acetylcholine receptor clusters on Xenopus muscles were concentrated at the cholinergic neuromuscular junctions by the movement of receptors from outside the junctions during development. The passive diffusion-trap mechanism explained the accumulation of synaptic receptors at synapses. 4) We found two endocytic pathways and pools of synaptic vesicles contributing to low- and high-frequency synaptic transmission at Drosophila nerve terminals. We then identified two Ca2+ channels designated for the low- and high-frequency endocytosis of synaptic vesicles, straightjacket Ca2+ channels in the active zone and La3+-sensitive Ca2+ channels in the inactive zone at the terminals, respectively. Recently, Drosophila melanogaster has been used as a model for studying the social brain, and the heat avoidance response of the flies was found to be socially enhanced. Future studies are expected to reveal mechanisms underlying social brain functions at the gene level.
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20
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Etherington SJ, Johnstone VPA, Everett AW. Modulation of synaptic vesicle exocytosis in muscle-dependent long-term depression at the amphibian neuromuscular junction. PLoS One 2014; 9:e87174. [PMID: 24489862 PMCID: PMC3904971 DOI: 10.1371/journal.pone.0087174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/20/2013] [Indexed: 11/24/2022] Open
Abstract
We have labeled recycling synaptic vesicles at the somatic Bufo marinus neuromuscular junction with the styryl dye FM2-10 and provide direct evidence for refractoriness of exocytosis associated with a muscle activity-dependent form of long-term depression (LTD) at this synapse. FM2-10 dye unloading experiments demonstrated that the rate of vesicle exocytosis from the release ready pool (RRP) of vesicles was more than halved in the LTD (induced by 20 min of low frequency stimulation). Recovery from LTD, observed as a partial recovery of nerve-evoked muscle twitch amplitude, was accompanied by partial recovery of the refractoriness of RRP exocytosis. Unexpectedly, paired pulse plasticity, another routinely used indicator of presynaptic forms of synaptic plasticity, was unchanged in the LTD. We conclude that the LTD induces refractoriness of the neuromuscular vesicle release machinery downstream of presynaptic calcium entry.
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Affiliation(s)
- Sarah J. Etherington
- School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Perth, Western Australia, Australia
- School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia
- * E-mail:
| | - Victoria P. A. Johnstone
- School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Perth, Western Australia, Australia
- Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Alan W. Everett
- School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Perth, Western Australia, Australia
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21
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Madeo G, Schirinzi T, Martella G, Latagliata EC, Puglisi F, Shen J, Valente EM, Federici M, Mercuri NB, Puglisi-Allegra S, Bonsi P, Pisani A. PINK1 heterozygous mutations induce subtle alterations in dopamine-dependent synaptic plasticity. Mov Disord 2013; 29:41-53. [PMID: 24167038 DOI: 10.1002/mds.25724] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 09/10/2013] [Accepted: 09/16/2013] [Indexed: 11/07/2022] Open
Abstract
Homozygous or compound heterozygous mutations in the phosphatase and tensin homolog-induced putative kinase 1 (PINK1) gene are causative of autosomal recessive, early onset Parkinson's disease. Single heterozygous mutations have been detected repeatedly both in a subset of patients and in unaffected individuals, and the significance of these mutations has long been debated. Several neurophysiological studies from non-manifesting PINK1 heterozygotes have demonstrated the existence of neural plasticity abnormalities, indicating the presence of specific endophenotypic traits in the heterozygous state. We performed a functional analysis of corticostriatal synaptic plasticity in heterozygous PINK1 knockout (PINK1(+/-) ) mice using a multidisciplinary approach and observed that, despite normal motor behavior, repetitive activation of cortical inputs to striatal neurons failed to induce long-term potentiation (LTP), whereas long-term depression was normal. Although nigral dopaminergic neurons exhibited normal morphological and electrophysiological properties with normal responses to dopamine receptor activation, a significantly lower dopamine release was measured in the striatum of PINK1(+/-) mice compared with control mice, suggesting that a decrease in stimulus-evoked dopamine overflow acts as a major determinant for the LTP deficit. Accordingly, pharmacological agents capable of increasing the availability of dopamine in the synaptic cleft restored normal LTP in heterozygous mice. Moreover, monoamine oxidase B inhibitors rescued physiological LTP and normal dopamine release. Our results provide novel evidence for striatal plasticity abnormalities, even in the heterozygous disease state. These alterations might be considered an endophenotype to this monogenic form of Parkinson's disease and a valid tool with which to characterize early disease stage and design possible disease-modifying therapies.
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Affiliation(s)
- Graziella Madeo
- Department of System Medicine, University of Rome "Tor Vergata", Rome, Italy
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22
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Morgan JR, Comstra HS, Cohen M, Faundez V. Presynaptic membrane retrieval and endosome biology: defining molecularly heterogeneous synaptic vesicles. Cold Spring Harb Perspect Biol 2013; 5:a016915. [PMID: 24086045 DOI: 10.1101/cshperspect.a016915] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The release and uptake of neurotransmitters by synaptic vesicles is a tightly controlled process that occurs in response to diverse stimuli at morphologically disparate synapses. To meet these architectural and functional synaptic demands, it follows that there should be diversity in the mechanisms that control their secretion and retrieval and possibly in the composition of synaptic vesicles within the same terminal. Here we pay particular attention to areas where such diversity is generated, such as the variance in exocytosis/endocytosis coupling, SNAREs defining functionally diverse synaptic vesicle populations and the adaptor-dependent sorting machineries capable of generating vesicle diversity. We argue that there are various synaptic vesicle recycling pathways at any given synapse and discuss several lines of evidence that support the role of the endosome in synaptic vesicle recycling.
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Affiliation(s)
- Jennifer R Morgan
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, Massachusetts 02543
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23
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Abstract
Synaptic vesicles release neurotransmitter at chemical synapses, thus initiating the flow of information in neural networks. To achieve this, vesicles undergo a dynamic cycle of fusion and retrieval to maintain the structural and functional integrity of the presynaptic terminals in which they reside. Moreover, compelling evidence indicates these vesicles differ in their availability for release and mobilization in response to stimuli, prompting classification into at least three different functional pools. Ongoing studies of the molecular and cellular bases for this heterogeneity attempt to link structure to physiology and clarify how regulation of vesicle pools influences synaptic strength and presynaptic plasticity. We discuss prevailing perspectives on vesicle pools, the role they play in shaping synaptic transmission, and the open questions that challenge current understanding.
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Affiliation(s)
- AbdulRasheed A Alabi
- Department of Molecular and Cellular Physiology, Stanford Institute for Neuro-Innovation and Translational Neurosciences, Stanford Medical School, Stanford, California 94305, USA
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Walters JW, Anderson JL, Bittman R, Pack M, Farber SA. Visualization of lipid metabolism in the zebrafish intestine reveals a relationship between NPC1L1-mediated cholesterol uptake and dietary fatty acid. CHEMISTRY & BIOLOGY 2012; 19:913-25. [PMID: 22749558 PMCID: PMC3408837 DOI: 10.1016/j.chembiol.2012.05.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 05/24/2012] [Accepted: 05/31/2012] [Indexed: 01/01/2023]
Abstract
The small intestine is the primary site of dietary lipid absorption in mammals. The balance of nutrients, microorganisms, bile, and mucus that determine intestinal luminal environment cannot be recapitulated ex vivo, thus complicating studies of lipid absorption. We show that fluorescently labeled lipids can be used to visualize and study lipid absorption in live zebrafish larvae. We demonstrate that the addition of a BODIPY-fatty acid to a diet high in atherogenic lipids enables imaging of enterocyte lipid droplet dynamics in real time. We find that a lipid-rich meal promotes BODIPY-cholesterol absorption into an endosomal compartment distinguishable from lipid droplets. We also show that dietary fatty acids promote intestinal cholesterol absorption by rapid re-localization of NPC1L1 to the intestinal brush border. These data illustrate the power of the zebrafish system to address longstanding questions in vertebrate digestive physiology.
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Affiliation(s)
- James W Walters
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
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25
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Nechipurenko IV, Broihier HT. FoxO limits microtubule stability and is itself negatively regulated by microtubule disruption. ACTA ACUST UNITED AC 2012; 196:345-62. [PMID: 22312004 PMCID: PMC3275378 DOI: 10.1083/jcb.201105154] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
FoxO inhibits microtubule stability in the central nervous system, making its degradation an essential component of a cell’s protective response to cytoskeletal insult. Transcription factors are essential for regulating neuronal microtubules (MTs) during development and after axon damage. In this paper, we identify a novel neuronal function for Drosophila melanogaster FoxO in limiting MT stability at the neuromuscular junction (NMJ). foxO loss-of-function NMJs displayed augmented MT stability. In contrast, motor neuronal overexpression of wild-type FoxO moderately destabilized MTs, whereas overexpression of constitutively nuclear FoxO severely destabilized MTs. Thus, FoxO negatively regulates synaptic MT stability. FoxO family members are well-established components of stress-activated feedback loops. We hypothesized that FoxO might also be regulated by cytoskeletal stress because it was well situated to shape neuronal MT organization after cytoskeletal damage. Indeed, levels of neuronal FoxO were strongly reduced after acute pharmacological MT disruption as well as sustained genetic disruption of the neuronal cytoskeleton. This decrease was independent of the dual leucine zipper kinase–Wallenda pathway and required function of Akt kinase. We present a model wherein FoxO degradation is a component of a stabilizing, protective response to cytoskeletal insult.
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Affiliation(s)
- Inna V Nechipurenko
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
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26
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Han Y, Yin H, Xu Y, Zhu Q, Luo J, Wang X, Chen G. Increased expression of calponin-3 in epileptic patients and experimental rats. Exp Neurol 2012; 233:430-7. [PMID: 22119193 DOI: 10.1016/j.expneurol.2011.11.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 10/23/2011] [Accepted: 11/08/2011] [Indexed: 02/07/2023]
Abstract
Calponin-3 is an actin-interacting protein and is expressed in the brain. Our previous microarray scan has found an up-regulation of calponin-3 gene CNN3 in the temporal lobe of patients with drug-resistant epilepsy. Here we investigated in epileptic patients the changes of brain and cerebrospinal fluid (CSF) calponin-3 expressions, and assessed calponin-3 expression pattern in a rat model of pilocarpine-induced epilepsy. We showed that in the temporal neocortices of 30 patients with drug-resistant epilepsy, both mRNA and protein level of calponin-3 were significantly increased. In addition, the augmentation of CSF calponin-3 from 126 epileptic patients was closely correlated with disease duration. Moreover, in the cortices of temporal lobes of pilocarpine-treated rats, calponin-3 increased along with the time and maintained at significant high levels for up to 2 months, while the up-regulation of hippocampal calponin-3 only occurred at 24h and 1 week. The elevated calponin-3 suggests that deregulation of actin filament dynamics in axonal and dendritic outgrowth and synaptic rearrangement may contribute to pathophysiology of epilepsy.
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Affiliation(s)
- Yanbing Han
- Department of Neurology, Chongqing Key Laboratory of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing, PR China
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27
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Li H, Foss SM, Dobryy YL, Park CK, Hires SA, Shaner NC, Tsien RY, Osborne LC, Voglmaier SM. Concurrent imaging of synaptic vesicle recycling and calcium dynamics. Front Mol Neurosci 2011; 4:34. [PMID: 22065946 PMCID: PMC3206542 DOI: 10.3389/fnmol.2011.00034] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2011] [Accepted: 10/05/2011] [Indexed: 11/13/2022] Open
Abstract
Synaptic transmission involves the calcium dependent release of neurotransmitter from synaptic vesicles. Genetically encoded optical probes emitting different wavelengths of fluorescent light in response to neuronal activity offer a powerful approach to understand the spatial and temporal relationship of calcium dynamics to the release of neurotransmitter in defined neuronal populations. To simultaneously image synaptic vesicle recycling and changes in cytosolic calcium, we developed a red-shifted reporter of vesicle recycling based on a vesicular glutamate transporter, VGLUT1-mOrange2 (VGLUT1-mOr2), and a presynaptically localized green calcium indicator, synaptophysin-GCaMP3 (SyGCaMP3) with a large dynamic range. The fluorescence of VGLUT1-mOr2 is quenched by the low pH of synaptic vesicles. Exocytosis upon electrical stimulation exposes the luminal mOr2 to the neutral extracellular pH and relieves fluorescence quenching. Reacidification of the vesicle upon endocytosis again reduces fluorescence intensity. Changes in fluorescence intensity thus monitor synaptic vesicle exo- and endocytosis, as demonstrated previously for the green VGLUT1-pHluorin. To monitor changes in calcium, we fused the synaptic vesicle protein synaptophysin to the recently improved calcium indicator GCaMP3. SyGCaMP3 is targeted to presynaptic varicosities, and exhibits changes in fluorescence in response to electrical stimulation consistent with changes in calcium concentration. Using real time imaging of both reporters expressed in the same synapses, we determine the time course of changes in VGLUT1 recycling in relation to changes in presynaptic calcium concentration. Inhibition of P/Q- and N-type calcium channels reduces calcium levels, as well as the rate of synaptic vesicle exocytosis and the fraction of vesicles released.
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Affiliation(s)
- Haiyan Li
- Department of Psychiatry, School of Medicine, University of California San Francisco San Francisco, CA, USA
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28
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Abstract
Cones release glutamate-filled vesicles continuously in darkness, and changing illumination modulates this release. Because sustained release in darkness is governed by vesicle replenishment rates, we analyzed how cone membrane potential regulates replenishment. Synaptic release from cones was measured by recording postsynaptic currents in Ambystoma tigrinum horizontal or OFF bipolar cells evoked by depolarization of simultaneously voltage-clamped cones. We measured replenishment after attaining a steady state between vesicle release and replenishment using trains of test pulses. Increasing Ca(2+) currents (I(Ca)) by changing the test step from -30 to -10 mV increased replenishment. Lengthening -30 mV test pulses to match the Ca(2+) influx during 25 ms test pulses to -10 mV produced similar replenishment rates. Reducing Ca(2+) driving force by using test steps to +30 mV slowed replenishment. Using UV flashes to reverse inhibition of I(Ca) by nifedipine accelerated replenishment. Increasing [Ca(2+)](i) by flash photolysis of caged Ca(2+) also accelerated replenishment. Replenishment, but not the initial burst of release, was enhanced by using an intracellular Ca(2+) buffer of 0.5 mm EGTA rather than 5 mm EGTA, and diminished by 1 mm BAPTA. This suggests that although release and replenishment exhibited similar Ca(2+) dependencies, release sites are <200 nm from Ca(2+) channels but replenishment sites are >200 nm away. Membrane potential thus regulates replenishment by controlling Ca(2+) influx, principally by effects on replenishment mechanisms but also by altering releasable pool size. This in turn provides a mechanism for converting changes in light intensity into changes in sustained release at the cone ribbon synapse.
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29
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Vos M, Lauwers E, Verstreken P. Synaptic mitochondria in synaptic transmission and organization of vesicle pools in health and disease. Front Synaptic Neurosci 2010; 2:139. [PMID: 21423525 PMCID: PMC3059669 DOI: 10.3389/fnsyn.2010.00139] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Accepted: 08/09/2010] [Indexed: 12/21/2022] Open
Abstract
Cell types rich in mitochondria, including neurons, display a high energy demand and a need for calcium buffering. The importance of mitochondria for proper neuronal function is stressed by the occurrence of neurological defects in patients suffering from a great variety of diseases caused by mutations in mitochondrial genes. Genetic and pharmacological evidence also reveal a role of these organelles in various aspects of neuronal physiology and in the pathogenesis of neurodegenerative disorders. Yet the mechanisms by which mitochondria can affect neurotransmission largely remain to be elucidated. In this review we focus on experimental data that suggest a critical function of synaptic mitochondria in the function and organization of synaptic vesicle pools, and in neurotransmitter release during intense neuronal activity. We discuss how calcium handling, ATP production and other mitochondrial mechanisms may influence synaptic vesicle pool organization and synaptic function. Given the link between synaptic mitochondrial function and neuronal communication, efforts toward better understanding mitochondrial biology may lead to novel therapeutic approaches of neurological disorders including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and psychiatric disorders that are at least in part caused by mitochondrial deficits.
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Affiliation(s)
- Melissa Vos
- Department of Molecular and Developmental Genetics VIB, Leuven, Belgium
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30
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Akbergenova Y, Bykhovskaia M. Synapsin regulates vesicle organization and activity-dependent recycling at Drosophila motor boutons. Neuroscience 2010; 170:441-52. [PMID: 20638447 DOI: 10.1016/j.neuroscience.2010.07.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 07/08/2010] [Accepted: 07/12/2010] [Indexed: 11/28/2022]
Abstract
Synapsin is a phosphoprotein reversibly associated with synaptic vesicles. We investigated synapsin function in mediating synaptic activity during intense stimulation at Drosophila motor boutons. Electron microscopy analysis of synapsin(-) boutons demonstrated that synapsin maintains vesicle clustering over the periphery of the bouton. Cyclosporin A pretreatment disrupted peripheral vesicle clustering, presumably due to increasing synapsin phosphorylated state. Labeling recycling vesicles with a fluorescent dye FM1-43 followed by photoconversion of the dye into electron dense product demonstrated that synapsin deficiency does not affect mixing of the reserve and recycling vesicle pools but selectively reduces the size of the reserve pool. Intense stimulation produced a significant increase in vesicle abundance and vesicle redistribution toward the central core of synapsin (+) boutons, while in synapsin (-) boutons the area occupied by vesicles did not change and the increase in vesicle numbers was not as prominent. However, intense stimulation produced an increase in basal release at synapsin(-) but not in synapsin(+) boutons, suggesting that synapsin may direct vesicles to the reserve pool. Finally, synapsin deficiency inhibited an increase in quantal size and formation of endosome-like cisternae, which was activated either by intense electrical stimulation or by high K(+) application. Taken together, these results elucidate a novel synapsin function, specifically, promoting vesicle reuptake and reserve pool formation upon intense stimulation.
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Affiliation(s)
- Y Akbergenova
- Lehigh University, Department of Biological Sciences, Bethlehem, PA 18015, USA
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31
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Ball RW, Warren-Paquin M, Tsurudome K, Liao EH, Elazzouzi F, Cavanagh C, An BS, Wang TT, White JH, Haghighi AP. Retrograde BMP signaling controls synaptic growth at the NMJ by regulating trio expression in motor neurons. Neuron 2010; 66:536-49. [PMID: 20510858 DOI: 10.1016/j.neuron.2010.04.011] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/02/2010] [Indexed: 10/19/2022]
Abstract
Retrograde signaling is essential for coordinating the growth of synaptic structures; however, it is not clear how it can lead to modulation of cytoskeletal dynamics and structural changes at presynaptic terminals. We show that loss of retrograde bone morphogenic protein (BMP) signaling at the Drosophila larval neuromuscular junction (NMJ) leads to a significant reduction in levels of Rac GEF Trio and a diminution of transcription at the trio locus. We further find that Trio is required in motor neurons for normal structural growth. Finally, we show that transgenic expression of Trio in motor neurons can partially restore NMJ defects in larvae mutant for BMP signaling. Based on our findings, we propose a model in which a retrograde BMP signal from the muscle modulates GTPase activity through transcriptional regulation of Rac GEF trio, thereby regulating the homeostasis of synaptic growth at the NMJ.
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Affiliation(s)
- Robin W Ball
- Department of Physiology, McGill University, Montréal, QC H3G 1Y6, Canada
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32
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Nurullin LF, Abramochkin DV, Tarasova NV, Rosenshtraukh LV, Nikolsky EE. Endo- and exocytosis of vesicles in the intramural nerve fibers of the rat right atrium. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2009; 428:423-6. [PMID: 19994780 DOI: 10.1134/s0012496609050093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- L F Nurullin
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, ul. Lobachevskogo 2/31, Kazan, 420111 Russia
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33
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Krasowska M, Grzywna ZJ, Mycielska ME, Djamgoz MBA. Fractal analysis and ionic dependence of endocytotic membrane activity of human breast cancer cells. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 38:1115-25. [PMID: 19618177 DOI: 10.1007/s00249-009-0516-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 06/24/2009] [Accepted: 06/29/2009] [Indexed: 10/20/2022]
Abstract
The endocytic membrane activities of two human breast cancer cell lines (MDA-MB-231 and MCF-7) of strong and weak metastatic potential, respectively, were studied in a comparative approach. Uptake of horseradish peroxidase was used to follow endocytosis. Dependence on ionic conditions and voltage-gated sodium channel (VGSC) activity were characterized. Fractal methods were used to analyze quantitative differences in vesicular patterning. Digital quantification showed that MDA-MB-231 cells took up more tracer (i.e., were more endocytic) than MCF-7 cells. For the former, uptake was totally dependent on extracellular Na(+) and partially dependent on extracellular and intracellular Ca(2+) and protein kinase activity. Analyzing the generalized fractal dimension (D(q )) and its Legendre transform f(alpha) revealed that under control conditions, all multifractal parameters determined had values greater for MDA-MB-231 compared with MCF-7 cells, consistent with endocytic/vesicular activity being more developed in the strongly metastatic cells. All fractal parameters studied were sensitive to the VGSC blocker tetrodotoxin (TTX). Some of the parameters had a "simple" dependence on VGSC activity, if present, whereby pretreatment with TTX reduced the values for the MDA-MB-231 cells and eliminated the differences between the two cell lines. For other parameters, however, there was a "complex" dependence on VGSC activity. The possible physical/physiological meaning of the mathematical parameters studied and the nature of involvement of VGSC activity in control of endocytosis/secretion are discussed.
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Affiliation(s)
- Monika Krasowska
- Division of Cell and Molecular Biology, Neuroscience Solutions to Cancer Research Group, Imperial College London, Sir Alexander Fleming Building, South Kensington Campus, London SW7 2AZ, UK.
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34
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Zefirov AL, Zakharov AV, Mukhamedyanov RD, Petrov AM. Peculiarities of synaptic vesicle recycling in frog and mouse motor nerve terminals. J EVOL BIOCHEM PHYS+ 2009. [DOI: 10.1134/s0022093008060082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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Gardiner J, Marc J. Disruption of normal cytoskeletal dynamics may play a key role in the pathogenesis of epilepsy. Neuroscientist 2009; 16:28-39. [PMID: 19429889 DOI: 10.1177/1073858409334422] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Epilepsy, a common disease affecting 1% to 2% of the population, is characterized by seizures, hyperexcitability at synapses, and aberrant extension of neurons following seizures. Much work has been done on the role of synaptic components in the pathogenesis of epilepsy, but relatively little attention has been given to the potential role of the cytoskeleton. The neuronal cytoskeleton consists of microtubules, actin filaments, intermediate filaments, and associated proteins. A number of mutations in both microtubule-associated proteins (MAPs) and actin-binding proteins, as well as altered expression levels of several cytoskeletal proteins, are known to be involved in epilepsy. These changes will affect the dynamics of the neuronal cytoskeleton and therefore are likely to contribute to the pathogenesis of epilepsy through mechanisms such as increased neurotrophic support to neurons and increased sprouting of mossy fibers. These changes may also contribute to hyperexcitability of neurons through an as yet unidentified mechanism.
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Affiliation(s)
- John Gardiner
- School of Biological Sciences, The University of Sydney, Camperdown, Australia.
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36
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Abstract
Proper synaptic function requires the seamless integration of the transport, assembly, and regulation of synaptic components and structures. Inasmuch as the synapse is often distant from the neuronal cell body, newly synthesized synaptic proteins, the precursors of synaptic vesicles, active zone compartments, channels and receptors, and mitochondria, must be transported along lengthy neuronal processes to participate in synaptogenesis. Neuronal transport is mediated by motor proteins that associate with their cargoes via adaptors (or receptors) and that travel along the cytoskeleton network within the neuronal processes. Thus, the identity of membranous protein cargoes and the specificity of motor-cargo interactions are critical for correctly targeting cargoes and properly assembling synapses in developing neurons and in remodeling synapses of mature neurons in response to neuronal activity. In this article, the authors review recent progress in characterizing microtubule- and actin-based motor proteins that are involved in delivering synaptic components and discuss potential mechanisms underlying the formation of motor-receptor-cargo complexes that contribute to synaptogenesis and activity-induced synaptic plasticity.
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Affiliation(s)
- Qian Cai
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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37
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Geiser DL, Shen MC, Mayo JJ, Winzerling JJ. Iron loaded ferritin secretion and inhibition by CI-976 in Aedes aegypti larval cells. Comp Biochem Physiol B Biochem Mol Biol 2009; 152:352-63. [PMID: 19168145 PMCID: PMC2649984 DOI: 10.1016/j.cbpb.2009.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 01/01/2009] [Accepted: 01/03/2009] [Indexed: 12/26/2022]
Abstract
Ferritin is a multimer of 24 subunits of heavy and light chains. In mammals, iron taken into cells is stored in ferritin or incorporated into iron-containing proteins. Very little ferritin is found circulating in mammalian serum; most is retained in the cytoplasm. Female mosquitoes, such as Aedes aegypti (yellow fever mosquito, Diptera), require a blood meal for oogenesis. Mosquitoes receive a potentially toxic level of iron in the blood meal which must be processed and stored. We demonstrate by (59)Fe pulse-chase experiments that cultured A. aegypti larval CCL-125 cells take up iron from culture media and store it in ferritin found mainly in the membrane fraction and secrete iron-loaded ferritin. We observe that in these larval cells ferritin co-localizes with ceramide-containing membranes in the absence of iron. With iron treatment, ferritin is found associated with ceramide-containing membranes as well as in cytoplasmic non-ceramide vesicles. Treatment of CCL-125 cells with iron and CI-976, an inhibitor of lysophospholipid acyl transferases, disrupts ferritin secretion with a concomitant decrease in cell viability. Interfering with ferritin secretion may limit the ability of mosquitoes to adjust to the high iron load of the blood meal and decrease iron delivery to the ovaries reducing egg numbers.
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Affiliation(s)
- Dawn L Geiser
- Department of Nutritional Sciences, The University of Arizona, Tucson, 85721, USA.
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38
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Akbergenova Y, Bykhovskaia M. Stimulation-induced formation of the reserve pool of vesicles in Drosophila motor boutons. J Neurophysiol 2009; 101:2423-33. [PMID: 19279147 DOI: 10.1152/jn.91122.2008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We combined electron microscopy (EM), synaptic vesicle staining by fluorescent marker FM1-43, photoconversion of the dye into an electron dense product, and electrical recordings of synaptic responses to study the distribution of reserve and recycling vesicles and its dependence on stimulation in Drosophila motor boutons. We showed that, at rest, vesicles are distributed over the periphery of the bouton, with the recycling and reserve pools being intermixed and the central core of the bouton being devoid of vesicles. Continuous high-frequency stimulation followed by a resting period mobilized the reserve vesicles into the recycling pool and, most notably, produced an increase in vesicle abundance. Recordings of synaptic activity from the temperature-sensitive endocytosis mutant shibire during continuous stimulation until complete depression provided an independent estimate of the increase in vesicle abundance on intense stimulation. EM analysis demonstrated that continuous stimulation produced an increase in the vesicle density, whereas during a subsequent resting period, vesicles filled empty areas of the bouton, spreading toward its central core. Although the observed structural potentiation did not alter basal transmitter release, it produced an increased synaptic enhancement during high-frequency stimulation. The latter effect was not observed when the boutons were potentiated using high-frequency stimulation without a subsequent resting period. We concluded therefore that the newly formed vesicles replenish the reserve pool during a resting period following intense stimulation.
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Affiliation(s)
- Yulia Akbergenova
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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39
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Zefirov AL, Zakharov AV, Mukhametzyanov RD, Petrov AM, Sitdikova GF. The vesicle cycle in motor nerve endings of the mouse diaphragm. ACTA ACUST UNITED AC 2009; 39:245-52. [PMID: 19234803 DOI: 10.1007/s11055-009-9122-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Indexed: 10/21/2022]
Abstract
Experiments on the mouse diaphragm muscle using intracellular microelectrode recordings and fluorescence microscopy were performed to study the dynamics of transmitter secretion and synaptic vesicle recycling processes (the exocytosis-endocytosis cycle) in motor nerve endings (NE) during prolonged rhythmic stimulation (20 impulses/sec). During stimulation, there were triphasic changes in the amplitude of endplate potentials (EPP): an initial rapid reduction, followed by prolonged (1-2 min) stabilization of amplitude, i.e., a plateau, and then a further slow decrease. Restoration of EPP amplitude after stimulation for 3 min occurred over a period of several seconds. Loading of synaptic vesicles with the fluorescent endocytic stain FM1-43 showed that rhythmic stimulation led to a gradual (over 5-6 min) decrease in NE fluorescence, demonstrating exocytosis of synaptic vesicles. Quantum analysis of the electrophysiological data and comparison of these data with results from fluorescence studies suggested that mouse NE have a high rate of endocytosis and reutilization of synaptic vesicles (the mean recycling time was about 50 sec), which may support the maintenance of reliable synaptic transmission during prolonged high-frequency activity. The sizes of the release-ready and recycling pools of synaptic vesicles were determined quantitatively. It is suggested that vesicle recycling in mouse NE occurs via a short, rapid pathway with incorporation into the recycling pool. Vesicles of the reserve pool are not used for transmitter secretion in the stimulation conditions used here.
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Affiliation(s)
- A L Zefirov
- Kazan State Medical University, 49 Butlerov Street, 420012, Kazan, Russia.
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40
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The role of cGMP-dependent signaling pathway in synaptic vesicle cycle at the frog motor nerve terminals. J Neurosci 2009; 28:13216-22. [PMID: 19052213 DOI: 10.1523/jneurosci.2947-08.2008] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The role of cGMP-dependent pathways in synaptic vesicle recycling in motor nerve endings during prolonged high-frequency stimulation was studied at frog neuromuscular junctions using electrophysiological and fluorescent methods. An increase of intracellular cGMP concentration (8-Br-cGMP or 8-pCPT-cGMP) significantly reduced the cycle time for synaptic vesicles through the enhancement of vesicular traffic rate from the recycling pool to the readily releasable pool and acceleration of fast endocytosis. Pharmacological inhibition of soluble guanylate cyclase or protein kinase G slowed down the rate of recycling as well as endocytosis of synaptic vesicles. The results suggest that cGMP-PKG-dependent pathway serves a significant function in the control of vesicular cycle in frog motor terminals.
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Kasprowicz J, Kuenen S, Miskiewicz K, Habets RLP, Smitz L, Verstreken P. Inactivation of clathrin heavy chain inhibits synaptic recycling but allows bulk membrane uptake. ACTA ACUST UNITED AC 2008; 182:1007-16. [PMID: 18762582 PMCID: PMC2528586 DOI: 10.1083/jcb.200804162] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Synaptic vesicle reformation depends on clathrin, an abundant protein that polymerizes around newly forming vesicles. However, how clathrin is involved in synaptic recycling in vivo remains unresolved. We test clathrin function during synaptic endocytosis using clathrin heavy chain (chc) mutants combined with chc photoinactivation to circumvent early embryonic lethality associated with chc mutations in multicellular organisms. Acute inactivation of chc at stimulated synapses leads to substantial membrane internalization visualized by live dye uptake and electron microscopy. However, chc-inactivated membrane cannot recycle and participate in vesicle release, resulting in a dramatic defect in neurotransmission maintenance during intense synaptic activity. Furthermore, inactivation of chc in the context of other endocytic mutations results in membrane uptake. Our data not only indicate that chc is critical for synaptic vesicle recycling but they also show that in the absence of the protein, bulk retrieval mediates massive synaptic membrane internalization.
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Affiliation(s)
- Jaroslaw Kasprowicz
- Department of Molecular and Developmental Genetics, VIB Flemish Institute for Biotechnology, 3000 Leuven, Belgium
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42
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Seid MA, Wehner R. Ultrastructure and synaptic differences of the boutons of the projection neurons between the lip and collar regions of the mushroom bodies in the ant, Cataglyphis albicans. J Comp Neurol 2008; 507:1102-8. [PMID: 18095324 DOI: 10.1002/cne.21600] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The mushroom bodies of insects are viewed as key neuropils for sensory integration and perhaps learning and memory. In Hymenoptera, particularly ants, the calyx of the mushroom bodies is divided into two main regions, the lip and the collar. Although most ants are highly dependent on olfaction and have enlarged calyces comprised mostly of lip, some ant groups are also highly visual and have well-developed collars. The desert ant Cataglyphis albicans, known for its navigational abilities, shifts from the dark olfactory demanding nest interior to the visually demanding desert environment, and unlike many other ants their mushroom bodies are comprised of both a well-developed lip and collar. In this study, using electron microscope serial-sectioning and 3D-reconstructions, we show that axonal processes that innervate the lip and collar are inherently different in structure and synaptic connectivity. The boutons of the lip are larger, with more synaptic vesicles and larger synapses than the collar, while boutons of the collar have more postsynaptic partners per synapse. Our morphological findings suggest that the signals originating from olfactory projection neurons that innervate the lip appear stronger and more likely to propagate than signals that innervate the collar, while the signals entering the collar appear relatively weaker and are further integrated between more postsynaptic partners. We discuss the differences of the signaling properties between the lip and collar projection neurons and suggest that the greater postsynaptic integration in the collar is presumably for spatial processing for visual navigation in Cataglyphis.
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Affiliation(s)
- Marc A Seid
- Zoologisches Institut, Universitt Zürich, Zürich, 8057 Switzerland.
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Santos MS, Li H, Voglmaier SM. Synaptic vesicle protein trafficking at the glutamate synapse. Neuroscience 2008; 158:189-203. [PMID: 18472224 DOI: 10.1016/j.neuroscience.2008.03.029] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 02/25/2008] [Accepted: 03/08/2008] [Indexed: 11/27/2022]
Abstract
Expression of the integral and associated proteins of synaptic vesicles is subject to regulation over time, by region, and in response to activity. The process by which changes in protein levels and isoforms result in different properties of neurotransmitter release involves protein trafficking to the synaptic vesicle. How newly synthesized proteins are incorporated into synaptic vesicles at the presynaptic bouton is poorly understood. During synaptogenesis, synaptic vesicle proteins sort through the secretory pathway and are transported down the axon in precursor vesicles that undergo maturation to form synaptic vesicles. Changes in protein content of synaptic vesicles could involve the formation of new vesicles that either mix with the previous complement of vesicles or replace them, presumably by their degradation or inactivation. Alternatively, new proteins could individually incorporate into existing synaptic vesicles, changing their functional properties. Glutamatergic vesicles likely express many of the same integral membrane proteins and share certain common mechanisms of biogenesis, recycling, and degradation with other synaptic vesicles. However, glutamatergic vesicles are defined by their ability to package glutamate for release, a property conferred by the expression of a vesicular glutamate transporter (VGLUT). VGLUTs are subject to regional, developmental, and activity-dependent changes in expression. In addition, VGLUT isoforms differ in their trafficking, which may target them to different pathways during biogenesis or after recycling, which may in turn sort them to different vesicle pools. Emerging data indicate that differences in the association of VGLUTs and other synaptic vesicle proteins with endocytic adaptors may influence their trafficking. These observations indicate that independent regulation of synaptic vesicle protein trafficking has the potential to influence synaptic vesicle protein composition, the maintenance of synaptic vesicle pools, and the release of glutamate in response to changing physiological requirements.
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Affiliation(s)
- M S Santos
- Department of Psychiatry, University of California School of Medicine, 401 Parnassus Avenue, LPPI-A101, San Francisco, CA 94143-0984, USA
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Yanay C, Morpurgo N, Linial M. Evolution of insect proteomes: insights into synapse organization and synaptic vesicle life cycle. Genome Biol 2008; 9:R27. [PMID: 18257909 PMCID: PMC2374702 DOI: 10.1186/gb-2008-9-2-r27] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 12/06/2007] [Accepted: 02/07/2008] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The molecular components in synapses that are essential to the life cycle of synaptic vesicles are well characterized. Nonetheless, many aspects of synaptic processes, in particular how they relate to complex behaviour, remain elusive. The genomes of flies, mosquitoes, the honeybee and the beetle are now fully sequenced and span an evolutionary breadth of about 350 million years; this provides a unique opportunity to conduct a comparative genomics study of the synapse. RESULTS We compiled a list of 120 gene prototypes that comprise the core of presynaptic structures in insects. Insects lack several scaffolding proteins in the active zone, such as bassoon and piccollo, and the most abundant protein in the mammalian synaptic vesicle, namely synaptophysin. The pattern of evolution of synaptic protein complexes is analyzed. According to this analysis, the components of presynaptic complexes as well as proteins that take part in organelle biogenesis are tightly coordinated. Most synaptic proteins are involved in rich protein interaction networks. Overall, the number of interacting proteins and the degrees of sequence conservation between human and insects are closely correlated. Such a correlation holds for exocytotic but not for endocytotic proteins. CONCLUSION This comparative study of human with insects sheds light on the composition and assembly of protein complexes in the synapse. Specifically, the nature of the protein interaction graphs differentiate exocytotic from endocytotic proteins and suggest unique evolutionary constraints for each set. General principles in the design of proteins of the presynaptic site can be inferred from a comparative study of human and insect genomes.
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Affiliation(s)
- Chava Yanay
- Department of Biological Chemistry, Institute of Life Sciences, Givat Ram Campus, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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Akbergenova Y, Bykhovskaia M. Synapsin maintains the reserve vesicle pool and spatial segregation of the recycling pool in Drosophila presynaptic boutons. Brain Res 2007; 1178:52-64. [PMID: 17904536 DOI: 10.1016/j.brainres.2007.08.042] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Revised: 08/09/2007] [Accepted: 08/13/2007] [Indexed: 10/22/2022]
Abstract
We employed optical detection of the lipophylic dye FM1-43 and focal recordings of quantal release to investigate how synapsin affects vesicle cycling at the neuromuscular junction of synapsin knockout (Syn KO) Drosophila. Loading the dye employing high K+ stimulation, which presumably involves the recycling pool of vesicles in exo/endocytosis, stained the periphery of wild type (WT) boutons, while in Syn KO the dye was redistributed towards the center of the bouton. When endocytosis was promoted by cyclosporin A pretreatment, the dye uptake was significantly enhanced in WT boutons, and the entire boutons were stained, suggesting staining of the reserve vesicle pool. In Syn KO boutons, the same loading paradigm produced fainter staining and significantly faster destaining. When the axon was stimulated electrically, a distinct difference in dye loading patterns was observed in WT boutons at different stimulation frequencies: a low stimulation frequency (3 Hz) produced a ring-shaped staining pattern, while at a higher frequency (10 Hz) the dye was redistributed towards the center of the bouton and the fluorescence intensity was significantly increased. This difference in staining patterns was essentially disrupted in Syn KO boutons, although synapsin did not affect the rate of quantal release. Stimulation of the nerve in the presence of bafilomycin, the blocker of the transmitter uptake, produced significantly stronger depression in Syn KO boutons. These results, taken together, suggest that synapsin maintains the reserve pool of vesicles and segregation between the recycling and reserve pools, and that it mediates mobilization of the reserve pool during intense stimulation.
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Affiliation(s)
- Yulia Akbergenova
- Department of Biological Sciences, Lehigh University, 111 Research Dr., Bethlehem, PA 18015, USA
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Crowley JJ, Carter AG, Regehr WG. Fast vesicle replenishment and rapid recovery from desensitization at a single synaptic release site. J Neurosci 2007; 27:5448-60. [PMID: 17507567 PMCID: PMC6672343 DOI: 10.1523/jneurosci.1186-07.2007] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
When the synaptic connection between two neurons consists of a small number of release sites, the ability to maintain transmission at high frequencies is limited by vesicle mobilization and by the response of postsynaptic receptors. These two properties were examined at single release sites between granule cells and stellate cells by triggering bursts of quantal events either with alpha-latrotoxin or with high-frequency trains of presynaptic activity. Bursts and evoked responses consisted of tens to hundreds of events with frequencies of up to hundreds per second. This indicates that single release sites can rapidly supply vesicles from a reserve pool to a release-ready pool. In addition, postsynaptic AMPA receptors recover from desensitization with a time constant of approximately 5 ms. Thus, even for synapses composed of a single release site, granule cells can effectively activate stellate cells during sustained high-frequency transmission because of rapid vesicle mobilization and fast recovery of AMPA receptors from desensitization.
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Affiliation(s)
- John J. Crowley
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Adam G. Carter
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Wade G. Regehr
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
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Dawson-Scully K, Lin Y, Imad M, Zhang J, Marin L, Horne JA, Meinertzhagen IA, Karunanithi S, Zinsmaier KE, Atwood HL. Morphological and functional effects of altered cysteine string protein at the Drosophila larval neuromuscular junction. Synapse 2007; 61:1-16. [PMID: 17068777 DOI: 10.1002/syn.20335] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The synaptic vesicle-associated cysteine string protein (CSP) is critical for neurotransmitter release at the neuromuscular junction (NMJ) of Drosophila, where the approximately 4% of mutant flies lacking CSP that survive to adulthood exhibit spastic jumping and shaking, temperature-sensitive paralysis, and premature death. Previously, it has been shown that CSP is also required for nerve terminal growth and the prevention of neurodegeneration in Drosophila and mice. At larval csp null mutant NMJs of Drosophila, intracellular recordings from the muscle showed that evoked release is significantly reduced at room temperature. However, it remained unclear whether the reduction in evoked release might be due to a loss of synaptic boutons, loss of synapses, and alterations in trafficking of vesicles to synapses. To resolve these issues, we have examined synaptic structure and function of csp null mutant NMJs at the level of single boutons. csp null mutations proportionally reduce the number of synaptic boutons of both motor neurons (1s and 1b) innervating larval muscles 6 and 7, while the number of synapses per bouton remains normal. However, focal recordings from individual synaptic boutons show that nerve-evoked neurotransmitter release is also impaired in both 1s and 1b boutons. Further, our ultrastructural analyses show that the reduction in evoked release at low stimulation frequencies is not due to a loss of synapses or to alterations in docked vesicles at synapses. Together, these data suggest that CSP promotes synaptic growth and evoked neurotransmitter release by mechanistically independent signaling pathways.
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Affiliation(s)
- Ken Dawson-Scully
- Department of Biology, University of Toronto, Mississauga, Ontario L5L 1C6, Canada.
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Megighian A, Rigoni M, Caccin P, Zordan MA, Montecucco C. A lysolecithin/fatty acid mixture promotes and then blocks neurotransmitter release at the Drosophila melanogaster larval neuromuscular junction. Neurosci Lett 2007; 416:6-11. [PMID: 17293048 DOI: 10.1016/j.neulet.2007.01.040] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 01/15/2007] [Accepted: 01/19/2007] [Indexed: 11/17/2022]
Abstract
The study of the effect of snake presynaptic neurotoxins with phospholipase A2 activity on nerve terminals has recently unveiled the inhibitory action of a lysophosphatidylcholine (LysoPC)/fatty acid mixture. We report here that these neurotoxins have no activity on Drosophila melanogaster nerve terminals. However, a 1:1 mixture of LysoPC and oleic acid induces an early increase, followed by an inhibition of both evoked and spontaneous neurotransmitter release. This effect is also induced by LysoPC alone. The present findings provide an indirect evidence that the lipid hemifusion-to-pore transition is a key event in neuroexocytosis in Drosophila. Moreover, these findings substantiate the use of LysoPC as a general agonist of membrane fusion at nerve terminals. This novel tool could contribute to the unraveling of the molecular steps involved in neuroexocytosis, particularly in Drosophila, where it is straightforward to combine it with electrophysiology and genetics.
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Affiliation(s)
- Aram Megighian
- Department of Human Anatomy and Physiology, Section of Physiology, University of Padova, Via Marzolo 3, Padova, Italy.
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Willeumier K, Pulst SM, Schweizer FE. Proteasome inhibition triggers activity-dependent increase in the size of the recycling vesicle pool in cultured hippocampal neurons. J Neurosci 2006; 26:11333-41. [PMID: 17079661 PMCID: PMC2665188 DOI: 10.1523/jneurosci.1684-06.2006] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The ubiquitin proteasome system, generally known for its function in protein degradation, also appears to play an important role in regulating membrane trafficking. A role for the proteasome in regulating presynaptic release and vesicle trafficking has been proposed for invertebrates, but it remains to be tested in mammalian presynaptic terminals. We used the fluorescent styrylpyridinium dye FM4-64 to visualize changes in the recycling pool of vesicles in hippocampal culture under pharmacological inhibition of the proteasome. We found that a 2 h inhibition increases the recycling pool of vesicles by 76%, with no change in the rate or total amount of dye release. Interestingly, enhancement did not depend on protein synthesis but did depend on synaptic activity; blocking action potentials during proteasome inhibition abolished the effect whereas increasing neuronal activity accelerated the effect with an increased recycling pool evident after 15 min. We propose that the proteasome acts as a negative-feedback regulator of synaptic transmission, possibly serving a homeostatic role.
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Affiliation(s)
- Kristen Willeumier
- Department of Neurobiology, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California 90095, USA
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Abstract
Synapses are packed with mitochondria, complex organelles with roles in energy metabolism, cell signaling, and calcium homeostasis. However, the precise mechanisms by which mitochondria influence neurotrans mission remain undefined. In this review, the authors discuss pharmacological and genetic analyses of synaptic mitochondrial function, focusing on their role in Ca2+ buffering and ATP production. Additionally, they will summarize recent data that implicate synaptic mitochondria in the regulation of neurotransmitter release during intense neuronal activity and link these findings to the pathogenesis of neurodegenerative diseases that feature disrupted synaptic mitochondria, including amyotrophic lateral sclerosis and hereditary spastic paraplegia.
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Affiliation(s)
- Cindy V Ly
- Department of Neuroscience and Molecular and Human Genetics, Howard Hughes Medical Institute Baylor College of Medicine, Houston, TX 77030, USA.
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