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Lee D, Hong JH. Physiological application of nanoparticles in calcium-related proteins and channels. Nanomedicine (Lond) 2019; 14:2479-2486. [PMID: 31456482 DOI: 10.2217/nnm-2019-0004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Nanoparticles (NPs) have been studied as therapeutic drug-delivery agents for promising clinical trial outcomes. Nanomaterial-based drugs can transfer conventional drugs to target lesions, such as tumors, with increasing efficiency by enhancing drug-cell interaction or drug absorption. Although they are favorable as efficient drug transfer systems, NPs also exhibit cytotoxicity that affects nonpathological regions. Here, we review the basic information behind NP-induced Ca2+ signaling and its participation in channel physiology and pathology. NPs are observed to demonstrate inhibitory or active effects on Ca2+ signaling. Thus, understanding Ca2+ signaling by NPs as a key mechanism in signal transduction will progress the application of nano-drugs in various diseases without deleterious effect.
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Affiliation(s)
- Dongun Lee
- Department of Physiology, Lee Gil Ya Cancer & Diabetes Institute, College of Medicine, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, South Korea
| | - Jeong Hee Hong
- Department of Physiology, Lee Gil Ya Cancer & Diabetes Institute, College of Medicine, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, South Korea
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2
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Hökfelt T, Barde S, Xu ZQD, Kuteeva E, Rüegg J, Le Maitre E, Risling M, Kehr J, Ihnatko R, Theodorsson E, Palkovits M, Deakin W, Bagdy G, Juhasz G, Prud’homme HJ, Mechawar N, Diaz-Heijtz R, Ögren SO. Neuropeptide and Small Transmitter Coexistence: Fundamental Studies and Relevance to Mental Illness. Front Neural Circuits 2018; 12:106. [PMID: 30627087 PMCID: PMC6309708 DOI: 10.3389/fncir.2018.00106] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 11/05/2018] [Indexed: 12/31/2022] Open
Abstract
Neuropeptides are auxiliary messenger molecules that always co-exist in nerve cells with one or more small molecule (classic) neurotransmitters. Neuropeptides act both as transmitters and trophic factors, and play a role particularly when the nervous system is challenged, as by injury, pain or stress. Here neuropeptides and coexistence in mammals are reviewed, but with special focus on the 29/30 amino acid galanin and its three receptors GalR1, -R2 and -R3. In particular, galanin's role as a co-transmitter in both rodent and human noradrenergic locus coeruleus (LC) neurons is addressed. Extensive experimental animal data strongly suggest a role for the galanin system in depression-like behavior. The translational potential of these results was tested by studying the galanin system in postmortem human brains, first in normal brains, and then in a comparison of five regions of brains obtained from depressed people who committed suicide, and from matched controls. The distribution of galanin and the four galanin system transcripts in the normal human brain was determined, and selective and parallel changes in levels of transcripts and DNA methylation for galanin and its three receptors were assessed in depressed patients who committed suicide: upregulation of transcripts, e.g., for galanin and GalR3 in LC, paralleled by a decrease in DNA methylation, suggesting involvement of epigenetic mechanisms. It is hypothesized that, when exposed to severe stress, the noradrenergic LC neurons fire in bursts and release galanin from their soma/dendrites. Galanin then acts on somato-dendritic, inhibitory galanin autoreceptors, opening potassium channels and inhibiting firing. The purpose of these autoreceptors is to act as a 'brake' to prevent overexcitation, a brake that is also part of resilience to stress that protects against depression. Depression then arises when the inhibition is too strong and long lasting - a maladaption, allostatic load, leading to depletion of NA levels in the forebrain. It is suggested that disinhibition by a galanin antagonist may have antidepressant activity by restoring forebrain NA levels. A role of galanin in depression is also supported by a recent candidate gene study, showing that variants in genes for galanin and its three receptors confer increased risk of depression and anxiety in people who experienced childhood adversity or recent negative life events. In summary, galanin, a neuropeptide coexisting in LC neurons, may participate in the mechanism underlying resilience against a serious and common disorder, MDD. Existing and further results may lead to an increased understanding of how this illness develops, which in turn could provide a basis for its treatment.
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Affiliation(s)
- Tomas Hökfelt
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Swapnali Barde
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Zhi-Qing David Xu
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Neurobiology, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing Laboratory of Brain Disorders (Ministry of Science and Technology), Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Eugenia Kuteeva
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Joelle Rüegg
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- The Center for Molecular Medicine, Stockholm, Sweden
- Swedish Toxicology Sciences Research Center, Swetox, Södertälje, Sweden
| | - Erwan Le Maitre
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Mårten Risling
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Jan Kehr
- Pronexus Analytical AB, Solna, Sweden
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Robert Ihnatko
- Department of Clinical Chemistry, Linköping University, Linköping, Sweden
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Elvar Theodorsson
- Department of Clinical Chemistry, Linköping University, Linköping, Sweden
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Miklos Palkovits
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - William Deakin
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, United Kingdom
| | - Gyorgy Bagdy
- Department of Pharmacodynamics, Semmelweis University, Budapest, Hungary
- MTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
- NAP 2-SE New Antidepressant Target Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary
| | - Gabriella Juhasz
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, United Kingdom
- Department of Pharmacodynamics, Semmelweis University, Budapest, Hungary
- SE-NAP2 Genetic Brain Imaging Migraine Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary
| | | | - Naguib Mechawar
- Douglas Hospital Research Centre, Verdun, QC, Canada
- Department of Psychiatry, McGill University, Montreal, QC, Canada
| | | | - Sven Ove Ögren
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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3
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Takeuchi S, Iwama S, Takagi H, Kiyota A, Nakashima K, Izumida H, Fujisawa H, Iwata N, Suga H, Watanabe T, Kaibuchi K, Oiso Y, Arima H, Sugimura Y. Tomosyn Negatively Regulates Arginine Vasopressin Secretion in Embryonic Stem Cell-Derived Neurons. PLoS One 2016; 11:e0164544. [PMID: 27732637 PMCID: PMC5061411 DOI: 10.1371/journal.pone.0164544] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/27/2016] [Indexed: 11/24/2022] Open
Abstract
Arginine vasopressin (AVP) is secreted via exocytosis; however, the precise molecular mechanism underlying the exocytosis of AVP remains to be elucidated. To better understand the mechanisms of AVP secretion, in our study we have identified proteins that bind with a 25 kDa synaptosomal-associated protein (SNAP25). SNAP25 plays a crucial role in exocytosis, in the posterior pituitary. Embryonic stem (ES) cell-derived AVP neurons were established to investigate the functions of the identified proteins. Using glutathione S-transferase (GST)-pulldown assays and proteomic analyses, we identified tomosyn-1 (syntaxin-binding protein 5) as a SNAP25-binding protein in the posterior pituitary. Coimmunoprecipitation assays indicated that tomosyn formed N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes with SNAP25 and syntaxin1. Immunohistochemistry showed that tomosyn localized to the posterior pituitary. Mouse ES cells self-differentiated into AVP neurons (mES-AVP) that expressed tomosyn and two transmembrane SNARE proteins, including SNAP25 and syntaxin1. KCl increased AVP secretion in mES-AVP, and overexpression of tomosyn-1 reduced KCl-stimulated AVP secretion. Downregulation of tomosyn-1 with siRNA increased KCl-stimulated AVP secretion. These results suggested that tomosyn-1 negatively regulated AVP secretion in mES-AVP and further suggest the possibility of using mES-AVP culture systems to evaluate the role of synaptic proteins from AVP neurons.
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Affiliation(s)
- Seiji Takeuchi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shintaro Iwama
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroshi Takagi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Atsushi Kiyota
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kohtaro Nakashima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hisakazu Izumida
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Haruki Fujisawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Naoko Iwata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hidetaka Suga
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Takashi Watanabe
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kozo Kaibuchi
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yutaka Oiso
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoshihisa Sugimura
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
- * E-mail:
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4
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Winkle CC, Taylor KL, Dent EW, Gallo G, Greif KF, Gupton SL. Beyond the cytoskeleton: The emerging role of organelles and membrane remodeling in the regulation of axon collateral branches. Dev Neurobiol 2016; 76:1293-1307. [PMID: 27112549 DOI: 10.1002/dneu.22398] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 04/11/2016] [Accepted: 04/21/2016] [Indexed: 12/19/2022]
Abstract
The generation of axon collateral branches is a fundamental aspect of the development of the nervous system and the response of axons to injury. Although much has been discovered about the signaling pathways and cytoskeletal dynamics underlying branching, additional aspects of the cell biology of axon branching have received less attention. This review summarizes recent advances in our understanding of key factors involved in axon branching. This article focuses on how cytoskeletal mechanisms, intracellular organelles, such as mitochondria and the endoplasmic reticulum, and membrane remodeling (exocytosis and endocytosis) contribute to branch initiation and formation. Together this growing literature provides valuable insight as well as a platform for continued investigation into how multiple aspects of axonal cell biology are spatially and temporally orchestrated to give rise to axon branches. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1293-1307, 2016.
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Affiliation(s)
- Cortney C Winkle
- Neurobiology Curriculum, University of North Carolina, Chapel Hill, North Carolina, 27599
| | - Kendra L Taylor
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, Wisconsin, 53705
| | - Erik W Dent
- Department of Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin, 53705
| | - Gianluca Gallo
- Lewis Katz School of Medicine, Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University, Philadelphia, Pennsylvania, 19140
| | - Karen F Greif
- Department of Biology, Bryn Mawr College, Bryn Mawr, Pennsylvania, 19010
| | - Stephanie L Gupton
- Department of Cell Biology and Physiology, Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina, 27599
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5
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Cheng J, Xiong Z, Duffney LJ, Wei J, Liu A, Liu S, Chen GJ, Yan Z. Methylphenidate exerts dose-dependent effects on glutamate receptors and behaviors. Biol Psychiatry 2014; 76:953-62. [PMID: 24832867 PMCID: PMC4194277 DOI: 10.1016/j.biopsych.2014.04.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 03/17/2014] [Accepted: 04/01/2014] [Indexed: 12/15/2022]
Abstract
BACKGROUND Methylphenidate (MPH), a psychostimulant drug used to treat attention-deficit/hyperactivity disorder, produces the effects of increasing alertness and improving attention. However, misuse of MPH has been associated with an increased risk of aggression and psychosis. We sought to determine the molecular mechanism underlying the complex actions of MPH. METHODS Adolescent (4-week-old) rats were given one injection of MPH at different doses. The impact of MPH on glutamatergic signaling in pyramidal neurons of prefrontal cortex was measured. Behavioral changes induced by MPH were also examined in parallel. RESULTS Administration of low-dose (.5 mg/kg) MPH selectively potentiated N-methyl-D-aspartate receptor (NMDAR)-mediated excitatory postsynaptic currents (EPSCs) via adrenergic receptor activation, whereas high-dose (10 mg/kg) MPH suppressed both NMDAR-mediated and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor-mediated EPSCs. The dual effects of MPH on EPSCs were associated with bidirectional changes in the surface level of glutamate receptor subunits. Behavioral tests also indicated that low-dose MPH facilitated prefrontal cortex-mediated temporal order recognition memory and attention. Animals injected with high-dose MPH exhibited significantly elevated locomotive activity. Inhibiting the function of synaptosomal-associated protein 25, a key SNARE protein involved in NMDAR exocytosis, blocked the increase of NMDAR-mediated EPSCs by low-dose MPH. In animals exposed to repeated stress, administration of low-dose MPH effectively restored NMDAR function and temporal order recognition memory via a mechanism dependent on synaptosomal-associated protein 25. CONCLUSIONS These results provide a potential mechanism underlying the cognitive-enhancing effects of low-dose MPH as well as the psychosis-inducing effects of high-dose MPH.
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Affiliation(s)
- Jia Cheng
- Department of Physiology and Biophysics, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, NY, USA
| | - Zhe Xiong
- Department of Physiology and Biophysics, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, NY, USA
| | - Lara J. Duffney
- Department of Physiology and Biophysics, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, NY, USA
| | - Jing Wei
- Department of Physiology and Biophysics, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, NY, USA
| | - Aiyi Liu
- Department of Physiology and Biophysics, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, NY, USA,Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Sihang Liu
- Department of Physiology and Biophysics, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, NY, USA
| | - Guo-Jun Chen
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Zhen Yan
- Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York; Department of Physiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.
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6
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Zhu Q, Yamakuchi M, Ture S, de la Luz Garcia-Hernandez M, Ko KA, Modjeski KL, LoMonaco MB, Johnson AD, O'Donnell CJ, Takai Y, Morrell CN, Lowenstein CJ. Syntaxin-binding protein STXBP5 inhibits endothelial exocytosis and promotes platelet secretion. J Clin Invest 2014; 124:4503-16. [PMID: 25244095 DOI: 10.1172/jci71245] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 07/24/2014] [Indexed: 01/25/2023] Open
Abstract
In humans, vWF levels predict the risk of myocardial infarction and thrombosis; however, the factors that influence vWF levels are not completely understood. Recent genome-wide association studies (GWAS) have identified syntaxin-binding protein 5 (STXBP5) as a candidate gene linked to changes in vWF plasma levels, though the functional relationship between STXBP5 and vWF is unknown. We hypothesized that STXBP5 inhibits endothelial cell exocytosis. We found that STXBP5 is expressed in human endothelial cells and colocalizes with and interacts with syntaxin 4. In human endothelial cells reduction of STXBP5 increased exocytosis of vWF and P-selectin. Mice lacking Stxbp5 had higher levels of vWF in the plasma, increased P-selectin translocation, and more platelet-endothelial interactions, which suggests that STXBP5 inhibits endothelial exocytosis. However, Stxbp5 KO mice also displayed hemostasis defects, including prolonged tail bleeding times and impaired mesenteric arteriole and carotid artery thrombosis. Furthermore, platelets from Stxbp5 KO mice had defects in platelet secretion and activation; thus, STXBP5 inhibits endothelial exocytosis but promotes platelet secretion. Our study reveals a vascular function for STXBP5, validates the functional relevance of a candidate gene identified by GWAS, and suggests that variation within STXBP5 is a genetic risk for venous thromboembolic disease.
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7
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Cheng J, Liu W, Duffney LJ, Yan Z. SNARE proteins are essential in the potentiation of NMDA receptors by group II metabotropic glutamate receptors. J Physiol 2013; 591:3935-47. [PMID: 23774277 DOI: 10.1113/jphysiol.2013.255075] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The group II metabotropic glutamate receptors (group II mGluRs) have emerged as the new drug targets for the treatment of mental disorders like schizophrenia. To understand the potential mechanisms underlying the antipsychotic effects of group II mGluRs, we examined their impact on NMDA receptors (NMDARs), since NMDAR hypofunction has been implicated in schizophrenia. The activation of group II mGluRs caused a significant enhancement of NMDAR currents in cortical pyramidal neurons, which was associated with increased NMDAR surface expression and synaptic localization. We further examined whether these effects of group II mGluRs are through the regulation of NMDAR exocytosis via SNARE proteins, a family of proteins involved in vesicle fusion. We found that the enhancing effect of APDC, a selective agonist of group II mGluRs, on NMDAR currents was abolished when botulinum toxin was delivered into the recorded neurons to disrupt the SNARE complex. Inhibiting the function of two key SNARE proteins, SNAP-25 and syntaxin 4, also eliminated the effect of APDC on NMDAR currents. Moreover, the application of APDC increased the activity of Rab4, a small Rab GTPase mediating fast recycling from early endosomes to the plasma membrane, and enhanced the interaction between syntaxin 4 and Rab4. Knockdown of Rab4 or expression of dominant-negative Rab4 attenuated the effect of APDC on NMDAR currents. Taken together, these results have identified key molecules involved in the group II mGluR-induced potentiation of NMDAR exocytosis and function.
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Affiliation(s)
- Jia Cheng
- Department of Physiology and Biophysics, State University of New York at Buffalo, NY 14214, USA
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8
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Greif KF, Asabere N, Lutz GJ, Gallo G. Synaptotagmin-1 promotes the formation of axonal filopodia and branches along the developing axons of forebrain neurons. Dev Neurobiol 2012; 73:27-44. [PMID: 22589224 DOI: 10.1002/dneu.22033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Revised: 04/29/2012] [Accepted: 05/08/2012] [Indexed: 01/01/2023]
Abstract
Synaptotagmin-1 (syt1) is a Ca(2+)-binding protein that functions in regulation of synaptic vesicle exocytosis at the synapse. Syt1 is expressed in many types of neurons well before synaptogenesis begins both in vivo and in vitro. To determine if expression of syt1 has a functional role in neuronal development before synapse formation, we examined the effects of syt1 overexpression and knockdown on the growth and branching of the axons of cultured primary embryonic day 8 chicken forebrain neurons. In vivo these neurons express syt1, and most have not yet extended axons. We present evidence that syt1 plays a role in regulating axon branching, while not regulating overall axon length. To study the effects of overexpression of syt1, we used adenovirus-mediated infection to introduce a syt1-YFP construct, or control GFP construct, into neurons. Syt1 levels were reduced using RNA interference. Overexpression of syt1 increased the formation of axonal filopodia and branches. Conversely, knockdown of syt1 decreased the number of axonal filopodia and branches. Time-lapse analysis of filopodial dynamics in syt1-overexpressing cells demonstrated that elevation of syt1 levels increased both the frequency of filopodial initiation and their lifespan. Taken together these data indicate that syt1 regulates the formation of axonal filopodia and branches before engaging in its conventional functions at the synapse.
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Affiliation(s)
- Karen F Greif
- Department of Biology, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, USA.
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9
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Zampese E, Pizzo P. Intracellular organelles in the saga of Ca2+ homeostasis: different molecules for different purposes? Cell Mol Life Sci 2012; 69:1077-104. [PMID: 21968921 PMCID: PMC11114864 DOI: 10.1007/s00018-011-0845-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 09/15/2011] [Accepted: 09/19/2011] [Indexed: 11/28/2022]
Abstract
An increase in the concentration of cytosolic free Ca(2+) is a key component regulating different cellular processes ranging from egg fertilization, active secretion and movement, to cell differentiation and death. The multitude of phenomena modulated by Ca(2+), however, do not simply rely on increases/decreases in its concentration, but also on specific timing, shape and sub-cellular localization of its signals that, combined together, provide a huge versatility in Ca(2+) signaling. Intracellular organelles and their Ca(2+) handling machineries exert key roles in this complex and precise mechanism, and this review will try to depict a map of Ca(2+) routes inside cells, highlighting the uniqueness of the different Ca(2+) toolkit components and the complexity of the interactions between them.
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Affiliation(s)
- Enrico Zampese
- Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
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10
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Tobin V, Schwab Y, Lelos N, Onaka T, Pittman QJ, Ludwig M. Expression of exocytosis proteins in rat supraoptic nucleus neurones. J Neuroendocrinol 2012; 24:629-41. [PMID: 21988098 PMCID: PMC3569506 DOI: 10.1111/j.1365-2826.2011.02237.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In magnocellular neurones of the supraoptic nucleus (SON), the neuropeptides vasopressin and oxytocin are synthesised and packaged into large dense-cored vesicles (LDCVs). These vesicles undergo regulated exocytosis from nerve terminals in the posterior pituitary gland and from somata/dendrites in the SON. Regulated exocytosis of LDCVs is considered to involve the soluble N-ethylmaleimide sensitive fusion protein attachment protein receptor (SNARE) complex [comprising vesicle associated membrane protein 2 (VAMP-2), syntaxin-1 and soluble N-ethylmaleimide attachment protein-25 (SNAP-25)] and regulatory proteins [such as synaptotagmin-1, munc-18 and Ca(2+) -dependent activator protein for secretion (CAPS-1)]. Using fluorescent immunocytochemistry and confocal microscopy, in both oxytocin and vasopressin neurones, we observed VAMP-2, SNAP-25 and syntaxin-1-immunoreactivity in axon terminals. The somata and dendrites contained syntaxin-1 and other regulatory exocytosis proteins, including munc-18 and CAPS-1. However, the distribution of VAMP-2 and synaptotagmin-1 in the SON was limited to putative pre-synaptic contacts because they co-localised with synaptophysin (synaptic vesicle marker) and had no co-localisation with either oxytocin or vasopressin. SNAP-25 immunoreactivity in the SON was limited to glial cell processes and was not detected in oxytocin or vasopressin somata/dendrites. The present results indicate differences in the expression and localisation of exocytosis proteins between the axon terminals and somata/dendritic compartment. The absence of VAMP-2 and SNAP-25 immunoreactivity from the somata/dendrites suggests that there might be different SNARE protein isoforms expressed in these compartments. Alternatively, exocytosis of LDCVs from somata/dendrites may use a different mechanism from that described by the SNARE complex theory.
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Affiliation(s)
- V. Tobin
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Y. Schwab
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Canada
| | - N. Lelos
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - T. Onaka
- Department of Physiology, Jichi Medical University, Tochigi, Japan
| | - Q. J. Pittman
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Canada
| | - M. Ludwig
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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11
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Abstract
Dendritic exocytosis underpins a broad range of integrative and homeostatic synaptic functions. Emerging data highlight the essential role of SNAREs in trafficking and fusion of secretory organelles with release of peptides and neurotransmitters from dendrites. This Perspective analyzes recent evidence inferring axo-dendritic polarization of vesicular release machinery and pinpoints progress made with existing challenges in this rapidly progressing field of dendritic research. Interpreting the relation of new molecular data to physiological results on secretion from dendrites would greatly advance our understanding of this facet of neuronal mechanisms.
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Affiliation(s)
- Saak V. Ovsepian
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - J. Oliver Dolly
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
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12
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Than A, Tan Y, Ong WY, Farooqui AA, Chen P. Kainate Receptors Mediate Regulated Exocytosis of Secretory Phospholipase A2 in SH-SY5Y Neuroblastoma Cells. Neurosignals 2011; 20:72-85. [DOI: 10.1159/000330414] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 06/27/2011] [Indexed: 01/03/2023] Open
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13
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Lanner JT, Georgiou DK, Joshi AD, Hamilton SL. Ryanodine receptors: structure, expression, molecular details, and function in calcium release. Cold Spring Harb Perspect Biol 2010; 2:a003996. [PMID: 20961976 DOI: 10.1101/cshperspect.a003996] [Citation(s) in RCA: 531] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Ryanodine receptors (RyRs) are located in the sarcoplasmic/endoplasmic reticulum membrane and are responsible for the release of Ca(2+) from intracellular stores during excitation-contraction coupling in both cardiac and skeletal muscle. RyRs are the largest known ion channels (> 2MDa) and exist as three mammalian isoforms (RyR 1-3), all of which are homotetrameric proteins that interact with and are regulated by phosphorylation, redox modifications, and a variety of small proteins and ions. Most RyR channel modulators interact with the large cytoplasmic domain whereas the carboxy-terminal portion of the protein forms the ion-conducting pore. Mutations in RyR2 are associated with human disorders such as catecholaminergic polymorphic ventricular tachycardia whereas mutations in RyR1 underlie diseases such as central core disease and malignant hyperthermia. This chapter examines the current concepts of the structure, function and regulation of RyRs and assesses the current state of understanding of their roles in associated disorders.
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Affiliation(s)
- Johanna T Lanner
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, Houston, Texas 77030,USA
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14
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Resende RR, da Costa JL, Kihara AH, Adhikari A, Lorençon E. Intracellular Ca2+ Regulation During Neuronal Differentiation of Murine Embryonal Carcinoma and Mesenchymal Stem Cells. Stem Cells Dev 2010; 19:379-94. [DOI: 10.1089/scd.2008.0289] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Rodrigo R. Resende
- Department of Physics, Institute of Exacts Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
- Instituto de Ensino e Pesquisa Santa Casa de BH (ISCM-BH), Belo Horizante, Brazil
| | - José L. da Costa
- Instrumental Analysis Laboratory, Criminalistic Institute of São Paulo, São Paulo, Brazil; Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Alexandre H. Kihara
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, Santo André, Brasil
| | - Avishek Adhikari
- Department of Biological Sciences, Columbia University, New York
| | - Eudes Lorençon
- Department of Physics, Institute of Exacts Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
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15
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Abstract
Information flow through neurones was historically considered to be linear, with dendrites receiving information from incoming synaptic terminals, the soma processing the information and the axon carrying it to the terminal that synapses upon another cell or end organ. However, recent studies have shown that dendrites can release transmitters themselves, and thereby communicate with neighbouring structures, whether these are adjacent neurones or incoming synapses. Due to their anatomical features, the magnocellular vasopressin and oxytocin containing neurones of the hypothalamic supraoptic and paraventricular nuclei and the dopamine neurones of the substantia nigra have revealed important aspects of dendritic function including mechanisms of dendritic transmitter release.
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Affiliation(s)
- F Bergquist
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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16
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Cnops L, Hu TT, Burnat K, Arckens L. Influence of binocular competition on the expression profiles of CRMP2, CRMP4, Dyn I, and Syt I in developing cat visual cortex. Cereb Cortex 2007; 18:1221-31. [PMID: 17951599 DOI: 10.1093/cercor/bhm157] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The visual cortex is vulnerable to changes in visual input, especially during the critical period when numerous molecules drive the refinement of the circuitry. From a list of potential actors identified in a recent proteomics study, we selected 2 collapsin response mediator proteins (CRMP2/CRMP4) and 2 synaptic proteins, Dynamin I (Dyn I) and Synaptotagmin I (Syt I), for in-depth analysis of their developmental expression profile in cat visual cortex. CRMP2 and CRMP4 levels were high early in life and clearly declined toward adulthood. In contrast, Dyn I expression levels progressively augmented during maturation. Syt I showed low levels at eye opening and in adults, high levels around the peak of the critical period, and maximal levels at juvenile age. We further determined a role for each molecule in ocular dominance plasticity. CRMP2 and Syt I levels decreased in area 17 upon monocular deprivation, whereas CRMP4 and Dyn I levels remained unaffected. In contrast, binocular removal of pattern vision had no influence on CRMP2 and Syt I expression in kitten area 17. This study illustrates that not the loss of quality of vision through visual deprivation, but disruption of normal binocular visual experience is crucial to induce the observed molecular changes.
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Affiliation(s)
- Lieselotte Cnops
- Laboratory of Neuroplasticity and Neuroproteomics, Katholieke Universiteit Leuven, Leuven, Belgium
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17
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Berninghausen O, Rahman MA, Silva JP, Davletov B, Hopkins C, Ushkaryov YA. Neurexin Ibeta and neuroligin are localized on opposite membranes in mature central synapses. J Neurochem 2007; 103:1855-63. [PMID: 17868325 PMCID: PMC2517655 DOI: 10.1111/j.1471-4159.2007.04918.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Synaptogenesis requires formation of trans-synaptic complexes between neuronal cell-adhesion receptors. Heterophilic receptor pairs, such as neurexin Ibeta and neuroligin, can mediate distinct intracellular signals and form different cytoplasmic scaffolds in the pre- and post-synaptic neuron, and may be particularly important for synaptogenesis. However, the functions of neurexin and neuroligin depend on their distribution in the synapse. Neuroligin has been experimentally assigned to the post-synaptic membrane, while the localization of neurexin remains unclear. To study the subcellular distribution of neurexin Ibeta and neuroligin in mature cerebrocortical synapses, we have developed a novel method for the physical separation of junctional membranes and their direct analysis by western blotting. Using urea and dithiothreitol, we disrupted trans-synaptic protein links, without dissolving the lipid phase, and fractionated the pre- and post-synaptic membranes. The purity of these fractions was validated by electron microscopy and western blotting using multiple synaptic markers. A quantitative analysis has confirmed that neuroligin is localized strictly in the post-synaptic membrane. We have also demonstrated that neurexin Ibeta is largely (96%) pre-synaptic. Thus, neurexin Ibeta and neuroligin normally form trans-synaptic complexes and can transduce bidirectional signals.
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Affiliation(s)
- Otto Berninghausen
- Division of Cell and Molecular Biology, Imperial College London, London, UK
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18
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Cnops L, Hu TT, Vanden Broeck J, Burnat K, Van Den Bergh G, Arckens L. Age- and experience-dependent expression of Dynamin I and Synaptotagmin I in cat visual system. J Comp Neurol 2007; 504:254-64. [PMID: 17640048 DOI: 10.1002/cne.21415] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Dynamin I (Dyn I) and Synaptotagmin I (Syt I) are essential for endocytosis-exocytosis processes, thus for neurotransmission. Despite their related function at presynaptic terminals, Dyn I and Syt I displayed opposite expression patterns during visual cortex maturation in the cat. Dyn I was more abundantly expressed in adults, while Syt I exhibited higher levels in kittens of postnatal day 30 (P30). In area 17 this developmental difference was most obvious in layers II/III. Layer VI displayed a strong hybridization signal for both molecules, independent of age. In addition, Syt I levels were higher in posterior compared to anterior area 17 in adult subjects. Moreover, in higher-order visual areas Syt I was unevenly distributed over the cortical layers, thereby setting clear areal boundaries in mature cortex. In contrast, Dyn I was rather homogeneously distributed over extrastriate areas at both ages. Both molecules thus demonstrated a widespread but different distribution and an opposite temporal expression pattern during visual system development. Notably, monocular deprivation during the critical period of ocular dominance plasticity significantly decreased Syt I expression levels in area 17 ipsilateral to the deprived eye, while no effect was observed on Dyn I expression. We therefore conclude that visual experience induces changes in Syt I expression that may reflect changes in constitutive exocytosis involved in postnatal structural refinements of the visual cortex. On the other hand, the spatial and temporal expression patterns of Dyn I correlate with the establishment and maintenance of the mature neuronal structure rather than neurite remodeling.
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Affiliation(s)
- Lieselotte Cnops
- Laboratory of Neuroplasticity and Neuroproteomics, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
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19
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Shinbori C, Saito M, Kinoshita Y, Satoh I, Kono T, Hanada T, Nanba E, Adachi K, Suzuki H, Yamada M, Satoh K. N-hexacosanol reverses diabetic induced muscarinic hypercontractility of ileum in the rat. Eur J Pharmacol 2006; 545:177-84. [PMID: 16872599 DOI: 10.1016/j.ejphar.2006.06.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 06/13/2006] [Accepted: 06/15/2006] [Indexed: 10/24/2022]
Abstract
Diabetic neuropathy, a major complication of diabetes mellitus, is associated with development of gastrointestinal motility dysfunction and autonomic neuropathy. N-hexacosanol has neurotrophic effects and exhibits a wide variety of biological actions. In this study, we investigated the effects of cyclohexenonic long-chain fatty alcohol (N-hexacosanol) on streptozotocin-diabetic hypercontractility in the rat ileum longitudinal muscles. Treatment with N-hexacosanol did not alter the diabetic status of the animals, i.e., body weight, serum glucose, and serum insulin levels, but significantly restored the thickness of intestine wall and ameliorated diabetes-induced hypercontractility of the rat ileum in a dose-dependent manner. Furthermore, N-hexacosanol reversed the diabetes-induced upregulation of intestinal muscarinic M(2) and M(3) receptors mRNAs in the streptozotocin-diabetic rats. These results indicate that N-hexacosanol has therapeutic effects on hypercontractility in the diabetic ileum by ameliorating overexpression of muscarinic M(2) and M(3) receptors mRNAs.
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Affiliation(s)
- Chiko Shinbori
- Department of Pathophysiological and Therapeutic Science, Division of Molecular Pharmacology, Tottori University Faculty of Medicine, 86 Nishimachi, Yonago, 683-8503 Japan
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20
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Jover E, Gonzalez de Aguilar JL, Luu B, Lutz-Bucher B. Effect of a cyclohexenonic long-chain fatty alcohol on calcium mobilization. Eur J Pharmacol 2005; 516:197-203. [PMID: 15978572 DOI: 10.1016/j.ejphar.2005.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Accepted: 05/05/2005] [Indexed: 10/25/2022]
Abstract
Cyclohexenonic long-chain fatty alcohols constitute a family of synthetic compounds with trophic, secretagogue and antioxidant properties. Despite their multiple biological actions in neuronal and non-neuronal tissues, the intracellular mechanisms underlying CFA activity remain unknown. In the present study, we show that 3-(15-hydroxypentadecyl)-2,4,4-trimethyl-2-cyclohexen-1-one (tCFA15) directly mobilizes Ca(2+) in the pituitary neural lobe synaptosomes and in primary sensory neurons from dorsal root ganglia. This effect is dependent on the presence of extracellular Ca(2+), but does not involve transmembrane voltage-operated calcium channels. Using a combination of pharmacological agents that block or deplete intracellular Ca(2+) stores, our results suggest the implication of a calcium induced-calcium release mechanism evoked by tCFA15-induced Ca(2+) influx. To our knowledge, these findings constitute the first attempt towards the comprehension of the biological actions of cyclohexenonic long-chain fatty alcohols at a molecular level.
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Affiliation(s)
- Emmanuel Jover
- Laboratoire de Neurophysiologie Cellulaire et Intégrée, UMR CNRS 7519, Neurotransmission et sécrétion neuroendocrine, France.
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21
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Maher BJ, Mackinnon RL, Bai J, Chapman ER, Kelly PT. Activation of Postsynaptic Ca2+Stores Modulates Glutamate Receptor Cycling in Hippocampal Neurons. J Neurophysiol 2005; 93:178-88. [PMID: 15604462 DOI: 10.1152/jn.00651.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We show that activation of postsynaptic inositol 1,4,5-tris-phosphate receptors (IP3Rs) with the IP3R agonist adenophostin A (AdA) produces large increases in AMPA receptor (AMPAR) excitatory postsynaptic current (EPSC) amplitudes at hippocampal CA1 synapses. Co-perfusion of the Ca2+chelator bis-( o-aminophenoxy)- N,N,N′,N′-tetraacetic acid strongly inhibited AdA-enhanced increases in EPSC amplitudes. We examined the role of AMPAR insertion/anchoring in basal synaptic transmission. Perfusion of an inhibitor of synaptotagmin-soluble n-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor SNARE-mediated exocytosis depressed basal EPSC amplitudes, whereas a peptide that inhibits GluR2/3 interactions with postsynaptic density-95 (PDZ) domain proteins glutamate receptor interacting protein (GRIP)/protein interacting with C-kinase-1 (PICK1) enhanced basal synaptic transmission. These results suggest that constitutive trafficking and anchoring of AMPARs help maintain basal synaptic transmission. The regulation of postsynaptic AMPAR trafficking involves synaptotagmin-SNARE-mediated vesicle exocytosis and interactions between AMPARs and the PDZ domains in GRIP/PICK1. We show that inhibitors of synaptotagmin-SNARE-mediated exocytosis, or interactions between AMPARs and GRIP/PICK1, attenuated AdA-enhanced increases in EPSC amplitudes. These results suggest that IP3R-mediated Ca2+release can enhance AMPAR EPSC amplitudes through mechanisms that involve AMPAR-PDZ interactions and/or synaptotagmin-SNARE-mediated receptor trafficking.
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Affiliation(s)
- Brady J Maher
- Department of Molecular Biosciences, 4006 Haworth Hall, The University of Kansas, Lawrence, KS 66045-2106, USA
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22
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Toselli M, Taglietti V. L-type calcium channel gating is modulated by bradykinin with a PKC-dependent mechanism in NG108-15 cells. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2004; 34:217-29. [PMID: 15536563 DOI: 10.1007/s00249-004-0444-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2004] [Revised: 09/14/2004] [Accepted: 09/16/2004] [Indexed: 11/24/2022]
Abstract
Bradykinin (BK) excites dorsal root ganglion cells, leading to the sensation of pain. The actions of BK are thought to be mediated by heterotrimeric G protein-regulated pathways. Indeed there is strong evidence that in different cell types BK is involved in phosphoinositide breakdown following activation of G(q/11). In the present study we show that the Ca(2+) current flowing through L-type voltage-gated Ca(2+) channels in NG108-15 cells (differentiated in vitro to acquire a neuronal phenotype), measured using the whole-cell patch clamp configuration, is reversibly inhibited by BK in a voltage-independent fashion, suggesting a cascade process where a second messenger system is involved. This inhibitory action of BK is mimicked by the application of 1,2-oleoyl-acetyl glycerol (OAG), an analog of diacylglycerol that activates PKC. Interestingly, OAG occluded the effects of BK and both effects were blocked by selective PKC inhibitors. The down modulation of single L-type Ca(2+) channels by BK and OAG was also investigated in cell-attached patches. Our results indicate that the inhibitory action of BK involves activation of PKC and mainly shows up in a significant reduction of the probability of channel opening, caused by an increase and clustering of null sweeps in response to BK.
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Affiliation(s)
- Mauro Toselli
- Dipartimento di Scienze Fisiologiche e Farmacologiche Cellulari e Molecolari and INFM, Universita' di Pavia, Via Forlanini 6, 27100 Pavia, Italy.
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23
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Schwab Y, Jahke R, Jover E. Expression of tetrodotoxin-sensitive and resistant sodium channels by rat melanotrophs. Neuroreport 2004; 15:1219-23. [PMID: 15129178 DOI: 10.1097/00001756-200405190-00028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Rat melanotrophs fire Na+ and Ca2(+)-dependent action potentials. Whereas the molecular identity of Ca2+ channels expressed by these cells is well documented, less is known about Na channels. We characterize the expression of seven sodium channel alpha-subunit and the beta1- and beta2-subunit mRNAs. The tetrodotoxin-resistant Nav1.8 and Nav1.9 alpha subunit mRNAs are detected in the newborn intermediate lobe and in cultured melanotrophs. Electrophysiological recordings further demonstrate the expression of both tetrodotoxin-sensitive and tetrodotoxin-resistant currents by dissociated melanotrophs. Moreover, activated sodium channels are able to elicit intracellular calcium waves, both in the absence or in the presence of tetrodotoxin. This work shows that rat melanotrophs express functional tetrodotoxin-resistant sodium channels, whose activation can lead to the generation of intracellular calcium waves.
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Affiliation(s)
- Yannick Schwab
- UMR-CNRS-ULP 7519, Laboratoire de Neurophysiologie Cellulaire et Intégrée, Université Louis Pasteur 21, rue René Descartes F-67084 Strasbourg-Cedex, France.
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24
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Tosetti P, Parente V, Taglietti V, Dunlap K, Toselli M. Chick RGS2L demonstrates concentration-dependent selectivity for pertussis toxin-sensitive and -insensitive pathways that inhibit L-type Ca2+ channels. J Physiol 2003; 549:157-69. [PMID: 12651916 PMCID: PMC2342929 DOI: 10.1113/jphysiol.2002.034439] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In neuronal cells, the influx of Ca2+ ions through voltage-dependent L-type calcium (L) channels couples excitation to multiple cellular functions. In addition to voltage, several neurotransmitters, hormones and cytokines regulate L channel gating via binding to G-protein-coupled receptors. Intracellular molecules that modify G-protein activity - such as regulator of G-protein-signalling (RGS) proteins - are therefore potential candidates for regulating Ca2+ influx through L channels. Here we show that a novel RGS2 splice variant from chick dorsal root ganglion (DRG) neurons, RGS2L, reduces bradykinin (BK)-mediated inhibition of neuronal L channels and accelerates recovery from inhibition. Chick RGS2 reduces the inhibition mediated by both the pertussis toxin (PTX)-sensitive (Gi/o-coupled) and the PTX-insensitive (presumably Gq/11-coupled) pathways. However, we demonstrate for the first time in a living cell that the extent of coupling to each pathway varies with RGS2L concentration. A low concentration of recombinant chick RGS2L (10 nM) preferentially reduces the inhibition mediated by the PTX-insensitive pathway, whereas a 100-fold higher concentration attenuates both PTX-sensitive- and PTX-insensitive-mediated components equally. Our data suggest that factors promoting RGS2L gene induction may regulate Ca2+ influx through L channels by recruiting low-affinity interactions with Gi/o that are absent at basal RGS2L levels.
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Affiliation(s)
- Patrizia Tosetti
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
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25
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Abstract
Classical transmitters and neuropeptides can be released from the dendrites of many neuronal populations, to act as retrograde signals that modulate synaptic transmission, electrical activity and, in some cases, morphology of the cell of origin. For the hypothalamic neuroendocrine cells that release vasopressin and oxytocin, the stimuli, mechanisms and physiological functions of dendritic release have been revealed in detail that is not yet available for other neurons. The regulation of dendritic transmitter release is complex and at least partially independent from axon terminal release. Here, we provide an overview of recent findings on the mechanisms and physiological consequences of dendritic neuropeptide release and place this in the context of discoveries of dendritic neurotransmitter release in other brain regions.
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Affiliation(s)
- Mike Ludwig
- Division of Biomedical Sciences, University of Edinburgh Medical School, George Square, Edinburgh EH8 9XD, UK.
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