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Mukherjee A, Katiyar R, Dembla E, Dembla M, Kumar P, Belkacemi A, Jung M, Beck A, Flockerzi V, Schwarz K, Schmitz F. Disturbed Presynaptic Ca 2+ Signaling in Photoreceptors in the EAE Mouse Model of Multiple Sclerosis. iScience 2020; 23:101830. [PMID: 33305185 PMCID: PMC7711289 DOI: 10.1016/j.isci.2020.101830] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 10/10/2020] [Accepted: 11/16/2020] [Indexed: 02/06/2023] Open
Abstract
Multiple sclerosis (MS) is a demyelinating disease caused by an auto-reactive immune system. Recent studies also demonstrated synapse dysfunctions in MS patients and MS mouse models. We previously observed decreased synaptic vesicle exocytosis in photoreceptor synapses in the EAE mouse model of MS at an early, preclinical stage. In the present study, we analyzed whether synaptic defects are associated with altered presynaptic Ca2+ signaling. Using high-resolution immunolabeling, we found a reduced signal intensity of Cav-channels and RIM2 at active zones in early, preclinical EAE. In line with these morphological alterations, depolarization-evoked increases of presynaptic Ca2+ were significantly smaller. In contrast, basal presynaptic Ca2+ was elevated. We observed a decreased expression of Na+/K+-ATPase and plasma membrane Ca2+ ATPase 2 (PMCA2), but not PMCA1, in photoreceptor terminals of EAE mice that could contribute to elevated basal Ca2+. Thus, complex Ca2+ signaling alterations contribute to synaptic dysfunctions in photoreceptors in early EAE. Less Cav-channels and RIM2 at the active zones of EAE photoreceptor synapses Decreased depolarization-evoked Ca2+-responses in EAE photoreceptor synapses Elevated basal, resting Ca2+ levels in preclinical EAE photoreceptor terminals Decreased expression of PMCA2 and Na+/K+-ATPase in EAE photoreceptor synapses
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Affiliation(s)
- Amrita Mukherjee
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Rashmi Katiyar
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Ekta Dembla
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Mayur Dembla
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Praveen Kumar
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Anouar Belkacemi
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Martin Jung
- Institute of Medical Biochemistry and Molecular Biology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Andreas Beck
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Veit Flockerzi
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Karin Schwarz
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Frank Schmitz
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
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2
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Manninen T, Saudargiene A, Linne ML. Astrocyte-mediated spike-timing-dependent long-term depression modulates synaptic properties in the developing cortex. PLoS Comput Biol 2020; 16:e1008360. [PMID: 33170856 PMCID: PMC7654831 DOI: 10.1371/journal.pcbi.1008360] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/22/2020] [Indexed: 12/26/2022] Open
Abstract
Astrocytes have been shown to modulate synaptic transmission and plasticity in specific cortical synapses, but our understanding of the underlying molecular and cellular mechanisms remains limited. Here we present a new biophysicochemical model of a somatosensory cortical layer 4 to layer 2/3 synapse to study the role of astrocytes in spike-timing-dependent long-term depression (t-LTD) in vivo. By applying the synapse model and electrophysiological data recorded from rodent somatosensory cortex, we show that a signal from a postsynaptic neuron, orchestrated by endocannabinoids, astrocytic calcium signaling, and presynaptic N-methyl-D-aspartate receptors coupled with calcineurin signaling, induces t-LTD which is sensitive to the temporal difference between post- and presynaptic firing. We predict for the first time the dynamics of astrocyte-mediated molecular mechanisms underlying t-LTD and link complex biochemical networks at presynaptic, postsynaptic, and astrocytic sites to the time window of t-LTD induction. During t-LTD a single astrocyte acts as a delay factor for fast neuronal activity and integrates fast neuronal sensory processing with slow non-neuronal processing to modulate synaptic properties in the brain. Our results suggest that astrocytes play a critical role in synaptic computation during postnatal development and are of paramount importance in guiding the development of brain circuit functions, learning and memory.
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Affiliation(s)
- Tiina Manninen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Department of Neurobiology, Stanford University, Stanford, CA, USA
| | - Ausra Saudargiene
- Neuroscience Institute, Lithuanian University of Health Sciences, Kaunas, Lithuania
- Department of Informatics, Vytautas Magnus University, Kaunas, Lithuania
| | - Marja-Leena Linne
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
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3
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Campbell JR, Li H, Wang Y, Kozhemyakin M, Hunt AJ, Liu X, Janz R, Heidelberger R. Phosphorylation of the Retinal Ribbon Synapse Specific t-SNARE Protein Syntaxin3B Is Regulated by Light via a Ca 2 +-Dependent Pathway. Front Cell Neurosci 2020; 14:587072. [PMID: 33192329 PMCID: PMC7606922 DOI: 10.3389/fncel.2020.587072] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 09/11/2020] [Indexed: 12/27/2022] Open
Abstract
Neurotransmitter release at retinal ribbon-style synapses utilizes a specialized t-SNARE protein called syntaxin3B (STX3B). In contrast to other syntaxins, STX3 proteins can be phosphorylated in vitro at T14 by Ca2+/calmodulin-dependent protein kinase II (CaMKII). This modification has the potential to modulate SNARE complex formation required for neurotransmitter release in an activity-dependent manner. To determine the extent to which T14 phosphorylation occurs in vivo in the mammalian retina and characterize the pathway responsible for the in vivo phosphorylation of T14, we utilized quantitative immunofluorescence to measure the levels of STX3 and STX3 phosphorylated at T14 (pSTX3) in the synaptic terminals of mouse retinal photoreceptors and rod bipolar cells (RBCs). Results demonstrate that STX3B phosphorylation at T14 is light-regulated and dependent upon the elevation of intraterminal Ca2+. In rod photoreceptor terminals, the ratio of pSTX3 to STX3 was significantly higher in dark-adapted mice, when rods are active, than in light-exposed mice. By contrast, in RBC terminals, the ratio of pSTX3 to STX3 was higher in light-exposed mice, when these terminals are active, than in dark-adapted mice. These results were recapitulated in the isolated eyecup preparation, but only when Ca2+ was included in the external medium. In the absence of external Ca2+, pSTX3 levels remained low regardless of light/dark exposure. Using the isolated RBC preparation, we next showed that elevation of intraterminal Ca2+ alone was sufficient to increase STX3 phosphorylation at T14. Furthermore, both the non-specific kinase inhibitor staurosporine and the selective CaMKII inhibitor AIP inhibited the Ca2+-dependent increase in the pSTX3/STX3 ratio in isolated RBC terminals, while in parallel experiments, AIP suppressed RBC depolarization-evoked exocytosis, measured using membrane capacitance measurements. Our data support a novel, illumination-regulated modulation of retinal ribbon-style synapse function in which activity-dependent Ca2+ entry drives the phosphorylation of STX3B at T14 by CaMKII, which in turn, modulates the ability to form SNARE complexes required for exocytosis.
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Affiliation(s)
- Joseph R Campbell
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Hongyan Li
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Yanzhao Wang
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Maxim Kozhemyakin
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Albert J Hunt
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Xiaoqin Liu
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Roger Janz
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, TX, United States.,MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
| | - Ruth Heidelberger
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, TX, United States.,MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
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4
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Zhou J, Ma C, Wang K, Li X, Jian X, Zhang H, Yuan J, Yin J, Chen J, Shi Y. Identification of rare and common variants in BNIP3L: a schizophrenia susceptibility gene. Hum Genomics 2020; 14:16. [PMID: 32393399 PMCID: PMC7212671 DOI: 10.1186/s40246-020-00266-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/24/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Schizophrenia is a chronic and severe mental disorder, and it has been predicted to be highly polygenic. Common SNPs located in or near BNIP3L were found to be genome-wide significantly associated with schizophrenia in recent genome-wide association studies. The purpose of our study is to investigate potential causal variants in BNIP3L gene. RESULTS We performed targeted sequencing for all exons and un-translated regions of BNIP3L gene among 1806 patients with schizophrenia and 998 healthy controls of Han Chinese origin. Three rare nonsynonymous mutations, BNIP3L (NM_004331): c.52A>G, c.167G>A and c.313A>T, were identified in schizophrenia cases, and two of them were newly reported. The frequencies of these rare nonsynonymous mutations were significantly different between schizophrenia cases and healthy controls. For the common variants, rs147389989 achieved significance in both allelic and genotypic distributions with schizophrenia. Rs1042992 and rs17310286 were significantly associated with schizophrenia in meta-analyses using PGC, CLOZUK, and our new datasets in this study. CONCLUSIONS Our findings provided further evidence that BNIP3L gene is a susceptibility gene of schizophrenia and revealed functional and potential causal mutations in BNIP3L. However, more functional validations are suggested to better understand the role of BNIP3L in the etiology of schizophrenia.
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Affiliation(s)
- Juan Zhou
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China
| | - Chuanchuan Ma
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China
| | - Ke Wang
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China
| | - Xiuli Li
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China
| | - Xuemin Jian
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China
| | - Han Zhang
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China
| | - Jianmin Yuan
- Brain Science Basic Laboratory, The Affiliated Wuxi Mental Health Center With Nanjing Medical University, Wuxi, 214151, Jiangsu Province, People's Republic of China
| | - Jiajun Yin
- Brain Science Basic Laboratory, The Affiliated Wuxi Mental Health Center With Nanjing Medical University, Wuxi, 214151, Jiangsu Province, People's Republic of China
| | - Jianhua Chen
- Shanghai Clinical Research Center for Mental Health, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200030, People's Republic of China. .,Department of Psychological Medicine, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
| | - Yongyong Shi
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China.
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5
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Müller M, Ahumada-Castro U, Sanhueza M, Gonzalez-Billault C, Court FA, Cárdenas C. Mitochondria and Calcium Regulation as Basis of Neurodegeneration Associated With Aging. Front Neurosci 2018; 12:470. [PMID: 30057523 PMCID: PMC6053519 DOI: 10.3389/fnins.2018.00470] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/20/2018] [Indexed: 12/31/2022] Open
Abstract
Age is the main risk factor for the onset of neurodegenerative diseases. A decline of mitochondrial function has been observed in several age-dependent neurodegenerative diseases and may be a major contributing factor in their progression. Recent findings have shown that mitochondrial fitness is tightly regulated by Ca2+ signals, which are altered long before the onset of measurable histopathology hallmarks or cognitive deficits in several neurodegenerative diseases including Alzheimer’s disease (AD), the most frequent cause of dementia. The transfer of Ca2+ from the endoplasmic reticulum (ER) to the mitochondria, facilitated by the presence of mitochondria-associated membranes (MAMs), is essential for several physiological mitochondrial functions such as respiration. Ca2+ transfer to mitochondria must be finely regulated because excess Ca2+ will disturb oxidative phosphorylation (OXPHOS), thereby increasing the generation of reactive oxygen species (ROS) that leads to cellular damage observed in both aging and neurodegenerative diseases. In addition, excess Ca2+ and ROS trigger the opening of the mitochondrial transition pore mPTP, leading to loss of mitochondrial function and cell death. mPTP opening probably increases with age and its activity has been associated with several neurodegenerative diseases. As Ca2+ seems to be the initiator of the mitochondrial failure that contributes to the synaptic deficit observed during aging and neurodegeneration, in this review, we aim to look at current evidence for mitochondrial dysfunction caused by Ca2+ miscommunication in neuronal models of neurodegenerative disorders related to aging, with special emphasis on AD.
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Affiliation(s)
- Marioly Müller
- Geroscience Center for Brain Health and Metabolism, Santiago, Chile.,Department of Medical Technology, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | | | - Mario Sanhueza
- Center for Integrative Biology, Faculty of Sciences, Universidad Mayor, Santiago, Chile
| | - Christian Gonzalez-Billault
- Geroscience Center for Brain Health and Metabolism, Santiago, Chile.,Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile.,The Buck Institute for Research on Aging, Novato, CA, United States
| | - Felipe A Court
- Geroscience Center for Brain Health and Metabolism, Santiago, Chile.,Center for Integrative Biology, Faculty of Sciences, Universidad Mayor, Santiago, Chile.,The Buck Institute for Research on Aging, Novato, CA, United States
| | - César Cárdenas
- Geroscience Center for Brain Health and Metabolism, Santiago, Chile.,Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile.,Anatomy and Developmental Biology Program, Institute of Biomedical Sciences, University of Chile, Santiago, Chile.,Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA, United States
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6
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Guo L, Tian J, Du H. Mitochondrial Dysfunction and Synaptic Transmission Failure in Alzheimer's Disease. J Alzheimers Dis 2018; 57:1071-1086. [PMID: 27662318 DOI: 10.3233/jad-160702] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Alzheimer's disease (AD) is a chronic neurodegenerative disorder, in which multiple risk factors converge. Despite the complexity of the etiology of the disease, synaptic failure is the pathological basis of cognitive impairment, the cardinal sign of AD. Decreased synaptic density, compromised synaptic transmission, and defected synaptic plasticity are hallmark synaptic pathologies accompanying AD. However, the mechanisms by which synapses are injured in AD-related conditions have not been fully elucidated. Mitochondria are a critical organelle in neurons. The pivotal role of mitochondria in supporting synaptic function and the concomitant occurrence of mitochondrial dysfunction with synaptic stress in postmortem AD brains as well as AD animal models seem to lend the credibility to the hypothesis that mitochondrial defects underlie synaptic failure in AD. This concept is further strengthened by the protective effect of mitochondrial medicine on synaptic function against the toxicity of amyloid-β, a key player in the pathogenesis of AD. In this review, we focus on the association between mitochondrial dysfunction and synaptic transmission deficits in AD. Impaired mitochondrial energy production, deregulated mitochondrial calcium handling, excess mitochondrial reactive oxygen species generation and release play a crucial role in mediating synaptic transmission deregulation in AD. The understanding of the role of mitochondrial dysfunction in synaptic stress may lead to novel therapeutic strategies for the treatment of AD through the protection of synaptic transmission by targeting to mitochondrial deficits.
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Affiliation(s)
- Lan Guo
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Jing Tian
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Heng Du
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA.,Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China
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7
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Strehler EE, Thayer SA. Evidence for a role of plasma membrane calcium pumps in neurodegenerative disease: Recent developments. Neurosci Lett 2018; 663:39-47. [PMID: 28827127 PMCID: PMC5816698 DOI: 10.1016/j.neulet.2017.08.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/09/2017] [Accepted: 08/14/2017] [Indexed: 01/20/2023]
Abstract
Plasma membrane Ca2+ ATPases (PMCAs) are a major system for calcium extrusion from all cells. Different PMCA isoforms and splice variants are involved in the precise temporal and spatial handling of Ca2+ signals and the re-establishment of resting Ca2+ levels in the nervous system. Lack or inappropriate expression of specific PMCAs leads to characteristic neuronal phenotypes, which may be reciprocally exacerbated by genetic predisposition through alleles in other genes that modify PMCA interactions, regulation, and function. PMCA dysfunction is often poorly compensated in neurons and may lead to changes in synaptic transmission, altered excitability and, with long-term calcium overload, eventual cell death. Decrease and functional decline of PMCAs are hallmarks of neurodegeneration during aging, and mutations in specific PMCAs are responsible for neuronal dysfunction and accelerated neurodegeneration in many sensory and cognitive diseases.
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Affiliation(s)
- Emanuel E Strehler
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA; Department of Biomedicine, University of Basel, Basel, Switzerland.
| | - Stanley A Thayer
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN, USA.
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8
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Datta P, Gilliam J, Thoreson WB, Janz R, Heidelberger R. Two Pools of Vesicles Associated with Synaptic Ribbons Are Molecularly Prepared for Release. Biophys J 2017; 113:2281-2298. [PMID: 28863864 DOI: 10.1016/j.bpj.2017.08.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 07/28/2017] [Accepted: 08/07/2017] [Indexed: 11/17/2022] Open
Abstract
Neurons that form ribbon-style synapses are specialized for continuous exocytosis. To this end, their synaptic terminals contain numerous synaptic vesicles, some of which are ribbon associated, that have difference susceptibilities for undergoing Ca2+-dependent exocytosis. In this study, we probed the relationship between previously defined vesicle populations and determined their fusion competency with respect to SNARE complex formation. We found that both the rapidly releasing vesicle pool and the releasable vesicle pool of the retinal bipolar cell are situated at the ribbon-style active zones, where they functionally interact. A peptide inhibitor of SNARE complex formation failed to block exocytosis from either pool, suggesting that these two vesicle pools have formed the SNARE complexes necessary for fusion. By contrast, a third, slower component of exocytosis was blocked by the peptide, as was the functional replenishment of vesicle pools, indicating that few vesicles outside of the ribbon-style active zones were initially fusion competent. In cone photoreceptors, similar to bipolar cells, fusion of the initial ribbon-associated synaptic vesicle cohort was not blocked by the SNARE complex-inhibiting peptide, whereas a later phase of exocytosis, attributable to the recruitment and subsequent fusion of vesicles newly arrived at the synaptic ribbons, was blocked. Together, our results support a model in which stimulus-evoked exocytosis in retinal ribbon synapses is SNARE-dependent; where vesicles higher up on the synaptic ribbon replenish the rapidly releasing vesicle pool; and at any given time, there are sufficient SNARE complexes to support the fusion of the entire ribbon-associated cohort of vesicles. An important implication of these results is that ribbon-associated vesicles can form intervesicular SNARE complexes, providing mechanistic insight into compound fusion at ribbon-style synapses.
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Affiliation(s)
- Proleta Datta
- Department of Neurobiology and Anatomy, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas; The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, Texas
| | - Jared Gilliam
- Department of Neurobiology and Anatomy, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas
| | - Wallace B Thoreson
- Truhlsen Eye Institute, Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska; Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska
| | - Roger Janz
- Department of Neurobiology and Anatomy, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas; The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, Texas
| | - Ruth Heidelberger
- Department of Neurobiology and Anatomy, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas; The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, Texas.
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9
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Stafford N, Wilson C, Oceandy D, Neyses L, Cartwright EJ. The Plasma Membrane Calcium ATPases and Their Role as Major New Players in Human Disease. Physiol Rev 2017; 97:1089-1125. [PMID: 28566538 DOI: 10.1152/physrev.00028.2016] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 01/20/2017] [Accepted: 01/23/2017] [Indexed: 02/07/2023] Open
Abstract
The Ca2+ extrusion function of the four mammalian isoforms of the plasma membrane calcium ATPases (PMCAs) is well established. There is also ever-increasing detail known of their roles in global and local Ca2+ homeostasis and intracellular Ca2+ signaling in a wide variety of cell types and tissues. It is becoming clear that the spatiotemporal patterns of expression of the PMCAs and the fact that their abundances and relative expression levels vary from cell type to cell type both reflect and impact on their specific functions in these cells. Over recent years it has become increasingly apparent that these genes have potentially significant roles in human health and disease, with PMCAs1-4 being associated with cardiovascular diseases, deafness, autism, ataxia, adenoma, and malarial resistance. This review will bring together evidence of the variety of tissue-specific functions of PMCAs and will highlight the roles these genes play in regulating normal physiological functions and the considerable impact the genes have on human disease.
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Affiliation(s)
- Nicholas Stafford
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Claire Wilson
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Delvac Oceandy
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Ludwig Neyses
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Elizabeth J Cartwright
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
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10
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Khariv V, Elkabes S. Contribution of Plasma Membrane Calcium ATPases to neuronal maladaptive responses: Focus on spinal nociceptive mechanisms and neurodegeneration. Neurosci Lett 2017; 663:60-65. [PMID: 28780172 DOI: 10.1016/j.neulet.2017.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/10/2017] [Accepted: 08/01/2017] [Indexed: 10/19/2022]
Abstract
Plasma membrane calcium ATPases (PMCAs) are ion pumps that expel Ca2+ from cells and maintain Ca2+ homeostasis. Four isoforms and multiple splice variants play important and non-overlapping roles in cellular function and integrity and have been implicated in diseases including disorders of the central nervous system (CNS). In particular, one of these isoforms, PMCA2, is critical for spinal cord (SC) neuronal function. PMCA2 expression is decreased in SC neurons at onset of symptoms in animal models of multiple sclerosis. Decreased PMCA2 expression affects the function and viability of SC neurons, with motor neurons being the most vulnerable population. Recent studies have also shown that PMCA2 could be an important contributor to pain processing in the dorsal horn (DH) of the SC. Pain sensitivity was altered in female, but not male, PMCA2+/- mice compared to PMCA2+/+ littermates in a modality-dependent manner. Changes in pain responsiveness in the female PMCA2+/- mice were paralleled by female-specific alterations in the expression of effectors, which have been implicated in the excitability of DH neurons, in mechanisms governing nociception and in the transmission of pain signals. Other PMCA isoforms and in particular, PMCA4, also contribute to the excitability of neurons in the dorsal root ganglia (DRG), which contain the first-order sensory neurons that convey nociceptive information from the periphery to the DH. These findings suggest that specific PMCA isoforms play specialized functions in neurons that mediate pain processing. Further investigations are necessary to unravel the precise contribution of PMCAs to mechanisms governing pathological pain in models of injury and disease.
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Affiliation(s)
- Veronika Khariv
- Department of Neurological Surgery, Reynolds Family Spine Laboratory, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States; Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
| | - Stella Elkabes
- Department of Neurological Surgery, Reynolds Family Spine Laboratory, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States.
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11
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Vaccaro V, Devine MJ, Higgs NF, Kittler JT. Miro1-dependent mitochondrial positioning drives the rescaling of presynaptic Ca2+ signals during homeostatic plasticity. EMBO Rep 2016; 18:231-240. [PMID: 28039205 PMCID: PMC5286383 DOI: 10.15252/embr.201642710] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 11/16/2016] [Accepted: 11/28/2016] [Indexed: 11/27/2022] Open
Abstract
Mitochondrial trafficking is influenced by neuronal activity, but it remains unclear how mitochondrial positioning influences neuronal transmission and plasticity. Here, we use live cell imaging with the genetically encoded presynaptically targeted Ca2+ indicator, SyGCaMP5, to address whether presynaptic Ca2+ responses are altered by mitochondria in synaptic terminals. We find that presynaptic Ca2+ signals, as well as neurotransmitter release, are significantly decreased in terminals containing mitochondria. Moreover, the localisation of mitochondria at presynaptic sites can be altered during long‐term activity changes, dependent on the Ca2+‐sensing function of the mitochondrial trafficking protein, Miro1. In addition, we find that Miro1‐mediated activity‐dependent synaptic repositioning of mitochondria allows neurons to homeostatically alter the strength of presynaptic Ca2+ signals in response to prolonged changes in neuronal activity. Our results support a model in which mitochondria are recruited to presynaptic terminals during periods of raised neuronal activity and are involved in rescaling synaptic signals during homeostatic plasticity.
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Affiliation(s)
- Victoria Vaccaro
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Michael J Devine
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Nathalie F Higgs
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Josef T Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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12
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Multifaceted plasma membrane Ca(2+) pumps: From structure to intracellular Ca(2+) handling and cancer. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:1351-63. [PMID: 26707182 DOI: 10.1016/j.bbamcr.2015.12.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/25/2015] [Accepted: 12/12/2015] [Indexed: 11/20/2022]
Abstract
Plasma membrane Ca(2+) ATPases (PMCAs) are intimately involved in the control of intracellular Ca(2+) concentration. They reduce Ca(2+) in the cytosol not only by direct ejection, but also by controlling the formation of inositol-1,4,5-trisphosphate and decreasing Ca(2+) release from the endoplasmic reticulum Ca(2+) pool. In mammals four genes (PMCA1-4) are expressed, and alternative RNA splicing generates more than twenty variants. The variants differ in their regulatory characteristics. They localize into highly specialized membrane compartments and respond to the incoming Ca(2+) with distinct temporal resolution. The expression pattern of variants depends on cell type; a change in this pattern can result in perturbed Ca(2+) homeostasis and thus altered cell function. Indeed, PMCAs undergo remarkable changes in their expression pattern during tumorigenesis that might significantly contribute to the unbalanced Ca(2+) homeostasis of cancer cells. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen.
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13
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Castellano-Muñoz M, Schnee ME, Ricci AJ. Calcium-induced calcium release supports recruitment of synaptic vesicles in auditory hair cells. J Neurophysiol 2015; 115:226-39. [PMID: 26510758 DOI: 10.1152/jn.00559.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 10/23/2015] [Indexed: 01/31/2023] Open
Abstract
Hair cells from auditory and vestibular systems transmit continuous sound and balance information to the central nervous system through the release of synaptic vesicles at ribbon synapses. The high activity experienced by hair cells requires a unique mechanism to sustain recruitment and replenishment of synaptic vesicles for continuous release. Using pre- and postsynaptic electrophysiological recordings, we explored the potential contribution of calcium-induced calcium release (CICR) in modulating the recruitment of vesicles to auditory hair cell ribbon synapses. Pharmacological manipulation of CICR with agents targeting endoplasmic reticulum calcium stores reduced both spontaneous postsynaptic multiunit activity and the frequency of excitatory postsynaptic currents (EPSCs). Pharmacological treatments had no effect on hair cell resting potential or activation curves for calcium and potassium channels. However, these drugs exerted a reduction in vesicle release measured by dual-sine capacitance methods. In addition, calcium substitution by barium reduced release efficacy by delaying release onset and diminishing vesicle recruitment. Together these results demonstrate a role for calcium stores in hair cell ribbon synaptic transmission and suggest a novel contribution of CICR in hair cell vesicle recruitment. We hypothesize that calcium entry via calcium channels is tightly regulated to control timing of vesicle fusion at the synapse, whereas CICR is used to maintain a tonic calcium signal to modulate vesicle trafficking.
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Affiliation(s)
- Manuel Castellano-Muñoz
- Department of Otolaryngology, Stanford University School of Medicine, Stanford, California; and
| | - Michael E Schnee
- Department of Otolaryngology, Stanford University School of Medicine, Stanford, California; and
| | - Anthony J Ricci
- Department of Otolaryngology, Stanford University School of Medicine, Stanford, California; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
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14
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Lee SY, Kim JH. Mechanisms underlying presynaptic Ca2+ transient and vesicular glutamate release at a CNS nerve terminal during in vitro ischaemia. J Physiol 2015; 593:2793-806. [PMID: 25833340 DOI: 10.1113/jp270060] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/30/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Here we demonstrate presynaptic responses and mechanisms of increased vesicular glutamate release during in vitro ischaemia in the calyx of Held terminal, an experimentally accessible presynaptic terminal in the CNS. The ischaemia-induced increase in presynaptic Ca(2+) was mediated by both Ca(2+) influx and Ca(2+) -induced Ca(2+) release from intracellular stores. The reverse operation of the plasma membrane Na(+) /Ca(2+) exchanger (NCX) plays a key role in Ca(2+) influx for triggering Ca(2+) release from intracellular stores at presynaptic terminals during in vitro ischaemia. Ca(2+) uptake via NCX underlies the ischaemia-induced Ca(2+) rise and the consequent increase in vesicular glutamate release from presynaptic terminals in the early phase of brain ischaemia. ABSTRACT An early consequence of brain ischaemia is an increase in vesicular glutamate release from presynaptic terminals. However, the mechanisms of this increased glutamate release are not fully understood. Here we studied presynaptic responses and mechanisms of increased glutamate release during in vitro ischaemia, using pre- and postsynaptic whole-cell recordings and presynaptic Ca(2+) imaging at the calyx of Held synapse in rat brainstem slices. Consistent with results from other brain regions, in vitro ischaemia significantly increased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) without affecting their amplitude, suggesting that ischaemia enhances vesicular glutamate release from presynaptic terminals. We found that ischaemia-induced vesicular glutamate release was dependent on a rise in basal Ca(2+) at presynaptic terminals, which resulted from extracellular Ca(2+) influx and Ca(2+) release from intracellular stores. During early ischaemia, increased Ca(2+) influx into presynaptic terminals was due to reverse operation of the plasma membrane Na(+) /Ca(2+) exchanger (NCX) rather than presynaptic depolarization or voltage-activated Ca(2+) currents. KB-R7943, an inhibitor of NCX, prevented the ischaemia-induced increases in presynaptic Ca(2+) and vesicular glutamate release. In addition, the removal of extracellular Na(+) completely inhibited the ischaemia-induced Ca(2+) rise. It therefore appears that a link between Na(+) accumulation and Ca(2+) uptake via NCX underlies the ischaemia-induced Ca(2+) rise and the consequent increase in vesicular glutamate release from presynaptic terminals in the early phase of brain ischaemia.
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Affiliation(s)
| | - Jun Hee Kim
- Department of Physiology.,Centre for Biomedical Neuroscience, University of Texas Health Science Centre, San Antonio, Texas, 78229, USA
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15
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Jiang ZJ, Wang CY, Xie X, Yang JF, Huang JN, Cao ZP, Xiao P, Li CH. Schizandrin ameliorates ovariectomy-induced memory impairment, potentiates neurotransmission and exhibits antioxidant properties. Br J Pharmacol 2015; 172:2479-92. [PMID: 25573619 DOI: 10.1111/bph.13078] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 11/18/2014] [Accepted: 12/25/2014] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND AND PURPOSE Schizandrin (SCH) has been reported to prevent or reduce learning and memory defects. However, it is not known whether SCH ameliorates cognitive impairments induced by oestrogen deficiency. In the present study, we investigated the effect of SCH on memory in ovariectomized (OVX) and non-OVX rats. EXPERIMENTAL APPROACH A passive avoidance test was used to evaluate the effect of SCH on memory. Field EPSPs were recorded in hippocampal slices using an electrophysiological method. In OVX rats, biochemical parameters in the bilateral hippocampus were measured; these included superoxide dismutase (SOD), malondialdehyde (MDA) and AChE. Also, the number of NADPH-diaphorase (NADPH-d) positive neurons was counted by NADPH-d histochemistry staining technique. KEY RESULTS Oral SCH improved the memory and facilitated the induction of long-term potentiation in non-OVX and OVX rats; this effect was more obvious in OVX rats. Similarly, SCH perfusion enhanced synaptic transmission in hippocampal slices from both non-OVX and OVX rats. However, SCH perfusion reduced the ratio of paired-pulse facilitation only in OVX but not in non-OVX rats. In addition, SCH decreased AChE activity and MDA level and increased SOD activity and the number of NADPH-d-positive neurons in OVX rats. CONCLUSIONS AND IMPLICATIONS SCH improves memory in OVX rats and its potential mechanisms may include a reduction in the loss of hippocampal NADPH-d positive neurons, an increase of antioxidant properties and a potentiation of synaptic transmission that possibly involves to enhance cholinergic function. Overall, our findings indicate that SCH has potential as a therapeutic strategy for the cognitive dysfunctions associated with the menopause.
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Affiliation(s)
- Zhong-Jiao Jiang
- School of Life Science, South China Normal University, Guangzhou, China
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16
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Lv T, Zhang PM, Gong HQ, Liang PJ. Caffeine-induced Ca(2+) oscillations in type I horizontal cell of carp retina: a mathematical model. Channels (Austin) 2014; 8:509-18. [PMID: 25483284 DOI: 10.4161/19336950.2014.965113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Oscillations in intracellular free Ca(2+) concentration ([Ca(2+)]i) have been observed in a variety of cell types. In the present study, we constructed a mathematical model to simulate the caffeine-induced [Ca(2+)]i oscillations based on experimental data obtained from isolated type I horizontal cell of carp retina. The results of model analysis confirm the notion that the caffeine-induced [Ca(2+)]i oscillations involve a number of cytoplasmic and endoplasmic Ca(2+) processes that interact with each other. Using this model, we evaluated the importance of store-operated channel (SOC) in caffeine-induced [Ca(2+)]i oscillations. The model suggests that store-operated Ca(2+) entry (SOCE) is elicited upon depletion of the endoplasmic reticulum (ER). When the SOC conductance is set to 0, caffeine-induced [Ca(2+)]i oscillations are abolished, which agrees with the experimental observation that [Ca(2+)]i oscillations were abolished when SOC was blocked pharmacologically, verifying that SOC is necessary for sustained [Ca(2+)]i oscillations.
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Key Words
- 2-APB, 2-Aminoethoxydiphenyl borate
- ANOVA, Analysis of variance
- CICR, Ca2+-induced Ca2+ release
- Ca2+ oscillations
- ER, Endoplasmic reticulum
- H1 HC, Type I horizontal cell
- HC, Horizontal cell
- L-VGCC, Ca2+channel
- NCX, Na+/Ca2+ exchanger
- PM, Plasma membrane
- PMCA, Plasma membrane Ca2+-ATPase
- RyR, Ryanodine receptor
- SERCA, Sarco/endoplasmic reticulum Ca2+-ATPase
- SNK, Student-Newman-Keuls
- SOC, Store-operated channel
- SOCE, Store-operated Ca2+ entry
- STIM, Stromal interaction molecule
- TRP, Transient receptor potential
- [Ca2+]ER, Free Ca2+ concentration inside the lumen of the ER
- [Ca2+]i, Intracellular free Ca2+ concentration
- caffeine
- computational model
- retinal horizontal cell
- ryanodine receptor
- store-operated channel
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Affiliation(s)
- Ting Lv
- a School of Biomedical Engineering ; Shanghai Jiao Tong University ; Shanghai , China
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17
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Scheff NN, Yilmaz E, Gold MS. The properties, distribution and function of Na(+)-Ca(2+) exchanger isoforms in rat cutaneous sensory neurons. J Physiol 2014; 592:4969-93. [PMID: 25239455 PMCID: PMC4259538 DOI: 10.1113/jphysiol.2014.278036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 09/10/2014] [Indexed: 11/08/2022] Open
Abstract
The Na(+)-Ca(2+) exchanger (NCX) appears to play an important role in the regulation of the high K(+)-evoked Ca(2+) transient in putative nociceptive dorsal root ganglion (DRG) neurons. The purpose of the present study was to (1) characterize the properties of NCX activity in subpopulations of DRG neurons, (2) identify the isoform(s) underlying NCX activity, and (3) begin to assess the function of the isoform(s) in vivo. In retrogradely labelled neurons from the glabrous skin of adult male Sprague-Dawley rats, NCX activity, as assessed with fura-2-based microfluorimetry, was only detected in putative nociceptive IB4+ neurons. There were two modes of NCX activity: one was evoked in response to relatively large and long lasting (∼325 nm for >12 s) increases in the concentration of intracellular Ca(2+) ([Ca(2+)]i), and a second was active at resting [Ca(2+)]i > ∼150 nm. There also were two modes of evoked activity: one that decayed relatively rapidly (<5 min) and a second that persisted (>10 min). Whereas mRNA encoding all three NCX isoforms (NCX1-3) was detected in putative nociceptive cutaneous neurons with single cell PCR, pharmacological analysis and small interfering RNA (siRNA) knockdown of each isoform in vivo suggested that NCX2 and 3 were responsible for NCX activity. Western blot analyses suggested that NCX isoforms were differentially distributed within sensory neurons. Functional assays of excitability, action potential propagation, and nociceptive behaviour suggest NCX activity has little influence on excitability per se, but instead influences axonal conduction velocity, resting membrane potential, and nociceptive threshold. Together these results indicate that the function of NCX in the regulation of [Ca(2+)]i in putative nociceptive neurons may be unique relative to other cells in which these exchanger isoforms have been characterized and it has the potential to influence sensory neuron properties at multiple levels.
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Affiliation(s)
- N N Scheff
- The Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA, USA Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - E Yilmaz
- The Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA, USA Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - M S Gold
- The Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA, USA Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
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18
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Lipin MY, Vigh J. Calcium spike-mediated digital signaling increases glutamate output at the visual threshold of retinal bipolar cells. J Neurophysiol 2014; 113:550-66. [PMID: 25339710 DOI: 10.1152/jn.00378.2014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Most retinal bipolar cells (BCs) transmit visual input from photoreceptors to ganglion cells using graded potentials, but some also generate calcium or sodium spikes. Sodium spikes are thought to increase temporal precision of light-evoked BC signaling; however, the role of calcium spikes in BCs is not fully understood. Here we studied how calcium spikes and graded responses mediate neurotransmitter release from Mb-type BCs, known to produce both. In dark-adapted goldfish retinal slices, light induced spikes in 40% of the axon terminals of intact Mbs; in the rest, light generated graded responses. These light-evoked membrane potentials were used to depolarize axotomized Mb terminals where depolarization-evoked calcium current (ICa) and consequent exocytosis-associated membrane capacitance increases (ΔCm) could be precisely measured. When evoked by identical dim light intensities, spiking responses transferred more calcium (Q(Ca)) and triggered larger exocytosis with higher efficiency (ΔCm/Q(Ca)) than graded potentials. Q(Ca) was translated into exocytosis linearly when transferred with spikes and supralinearly when transferred with graded responses. At the Mb output (ΔCm), spiking responses coded light intensity with numbers and amplitude whereas graded responses coded with amplitude, duration, and steepness. Importantly, spiking responses saturated exocytosis within scotopic range but graded potentials did not. We propose that calcium spikes in Mbs increase signal input-output ratio by boosting Mb glutamate release at threshold intensities. Therefore, spiking Mb responses are suitable to transfer low-light-intensity signals to ganglion cells with higher gain, whereas graded potentials signal for light over a wider range of intensities at the Mb output.
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Affiliation(s)
- Mikhail Y Lipin
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Jozsef Vigh
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
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19
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Hogan QH, Sprick C, Guo Y, Mueller S, Bienengraeber M, Pan B, Wu HE. Divergent effects of painful nerve injury on mitochondrial Ca(2+) buffering in axotomized and adjacent sensory neurons. Brain Res 2014; 1589:112-25. [PMID: 25251590 DOI: 10.1016/j.brainres.2014.09.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 09/09/2014] [Accepted: 09/15/2014] [Indexed: 02/05/2023]
Abstract
Mitochondria critically regulate cytoplasmic Ca(2+) concentration ([Ca(2+)]c), but the effects of sensory neuron injury have not been examined. Using FCCP (1µM) to eliminate mitochondrial Ca(2+) uptake combined with oligomycin (10µM) to prevent ATP depletion, we first identified features of depolarization-induced neuronal [Ca(2+)]c transients that are sensitive to blockade of mitochondrial Ca(2+) buffering in order to assess mitochondrial contributions to [Ca(2+)]c regulation. This established the loss of a shoulder during the recovery of the depolarization (K(+))-induced transient, increased transient peak and area, and elevated shoulder level as evidence of diminished mitochondrial Ca(2+) buffering. We then examined transients in Control neurons and neurons from the 4th lumbar (L4) and 5th lumbar (L5) dorsal root ganglia after L5 spinal nerve ligation (SNL). The SNL L4 neurons showed decreased transient peak and area compared to control neurons, while the SNL L5 neurons showed increased shoulder level. Additionally, SNL L4 neurons developed shoulders following transients with lower peaks than Control neurons. Application of FCCP plus oligomycin elevated resting [Ca(2+)]c in SNL L4 neurons more than in Control neurons. Whereas application of FCCP plus oligomycin 2s after neuronal depolarization initiated mitochondrial Ca(2+) release in most Control and SNL L4 neurons, this usually failed to release mitochondrial Ca(2+) from SNL L5 neurons. For comparable cytoplasmic Ca(2+) loads, the releasable mitochondrial Ca(2+) in SNL L5 neurons was less than Control while it was increased in SNL L4 neurons. These findings show diminished mitochondrial Ca(2+) buffering in axotomized SNL L5 neurons but enhanced Ca(2+) buffering by neurons in adjacent SNL L4 neurons.
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Affiliation(s)
- Quinn H Hogan
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA; Zablocki VA Medical Center, 5000 W National Avenue, Milwaukee, WI 53295, USA
| | - Chelsea Sprick
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA
| | - Yuan Guo
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA
| | - Samantha Mueller
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA
| | - Martin Bienengraeber
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA; Department of Pharmacology and Toxicology, Medical College of Wisconsin, USA
| | - Bin Pan
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA
| | - Hsiang-En Wu
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank, Milwaukee, WI 53226, USA.
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20
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Jonas EA, Porter GA, Alavian KN. Bcl-xL in neuroprotection and plasticity. Front Physiol 2014; 5:355. [PMID: 25278904 PMCID: PMC4166110 DOI: 10.3389/fphys.2014.00355] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 09/02/2014] [Indexed: 01/14/2023] Open
Abstract
Accepted features of neurodegenerative disease include mitochondrial and protein folding dysfunction and activation of pro-death factors. Neurons that experience high metabolic demand or those found in organisms with genetic mutations in proteins that control cell stress may be more susceptible to aging and neurodegenerative disease. In neurons, events that normally promote growth, synapse formation, and plasticity are also often deployed to control neurotoxicity. Such protective strategies are coordinated by master stress-fighting proteins. One such specialized protein is the anti-cell death Bcl-2 family member Bcl-xL, whose myriad death-protecting functions include enhancement of bioenergetic efficiency, prevention of mitochondrial permeability transition channel activity, protection from mitochondrial outer membrane permeabilization (MOMP) to pro-apoptotic factors, and improvement in the rate of vesicular trafficking. Synapse formation and normal neuronal activity provide protection from neuronal death. Therefore, Bcl-xL brings about synapse formation as a neuroprotective strategy. In this review we will consider how this multi-functional master regulator protein uses many strategies to enhance synaptic and neuronal function and thus counteracts neurodegenerative stimuli.
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Affiliation(s)
- Elizabeth A Jonas
- Section of Endocrinology, Department of Internal Medicine, Yale University New Haven, CT, USA ; Department of Neurobiology, Yale University New Haven, CT, USA
| | - George A Porter
- Departments of Pediatrics (Cardiology), University of Rochester Medical Center Rochester, NY, USA ; Internal Medicine (Aab Cardiovascular Research Institute), University of Rochester Medical Center Rochester, NY, USA ; Department of Pharmacology and Physiology, University of Rochester Medical Center Rochester, NY, USA
| | - Kambiz N Alavian
- Division of Brain Sciences, Department of Medicine, Imperial College London London, UK
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21
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Tang H, Pan R, Fang W, Xing Y, Chen D, Chen X, Yu Y, Wang J, Gong Z, Xiong G, Dong J. Curcumin ameliorates hippocampal neuron damage induced by human immunodeficiency virus-1. Neural Regen Res 2014; 8:1368-75. [PMID: 25206431 PMCID: PMC4107768 DOI: 10.3969/j.issn.1673-5374.2013.15.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 03/29/2013] [Indexed: 12/21/2022] Open
Abstract
Our previous studies have shown that infection with the gp120 V3 loop can cause human immunodeficiency virus-1 associated neurocognitive disorders. Curcumin has been shown to improve these effects to some degree, but the precise mechanisms remain unknown. The present study analyzed the neuroprotective effect and mechanism of curcumin in relation to hippocampal neurons. Results showed that 1 nmol/L gp120 V3 loop suppressed the growth of synapses. After administration of 1 μmol/L curcumin, synaptic growth improved. Curcumin is neuroprotective against gp120 V3 loop-induced neuronal damage by inhibiting the activation of L-type calcium currents, relieving intracellular Ca(2+) overload, promoting Bcl-2 expression, and inhibiting Bax activation. The effect of curcumin was identical to nimodipine, suggesting that curcumin has the same neuroprotective effects against gp120 V3 loop-induced neuronal damage.
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Affiliation(s)
- Hongmei Tang
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Institute of Brain Research, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Joint Laboratory for Brain Function and Health of Jinan University and the University of Hong Kong, Guangzhou 510632, Guangdong Province, China
| | - Rui Pan
- Department of Orthopedics, First Affiliated Hospital, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China
| | - Wenli Fang
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China
| | - Yanyan Xing
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Institute of Brain Research, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Joint Laboratory for Brain Function and Health of Jinan University and the University of Hong Kong, Guangzhou 510632, Guangdong Province, China
| | - Dexi Chen
- STD/AIDS Research Lab, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
| | - Xiaobao Chen
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China
| | - Yuanyuan Yu
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China
| | - Junbing Wang
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Institute of Brain Research, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Joint Laboratory for Brain Function and Health of Jinan University and the University of Hong Kong, Guangzhou 510632, Guangdong Province, China
| | - Zheng Gong
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Institute of Brain Research, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Joint Laboratory for Brain Function and Health of Jinan University and the University of Hong Kong, Guangzhou 510632, Guangdong Province, China
| | - Guoyin Xiong
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Institute of Brain Research, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Joint Laboratory for Brain Function and Health of Jinan University and the University of Hong Kong, Guangzhou 510632, Guangdong Province, China
| | - Jun Dong
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Institute of Brain Research, Medical College of Jinan University, Guangzhou 510632, Guangdong Province, China ; Joint Laboratory for Brain Function and Health of Jinan University and the University of Hong Kong, Guangzhou 510632, Guangdong Province, China
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22
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Van Hook MJ, Thoreson WB. Endogenous calcium buffering at photoreceptor synaptic terminals in salamander retina. Synapse 2014; 68:518-28. [PMID: 25049035 DOI: 10.1002/syn.21768] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 06/09/2014] [Accepted: 07/02/2014] [Indexed: 11/12/2022]
Abstract
Calcium operates by several mechanisms to regulate glutamate release at rod and cone synaptic terminals. In addition to serving as the exocytotic trigger, Ca2+ accelerates replenishment of vesicles in cones and triggers Ca2+-induced Ca2+ release (CICR) in rods. Ca2+ thereby amplifies sustained exocytosis, enabling photoreceptor synapses to encode constant and changing light. A complete picture of the role of Ca2+ in regulating synaptic transmission requires an understanding of the endogenous Ca2+ handling mechanisms at the synapse. We therefore used the "added buffer" approach to measure the endogenous Ca2+ binding ratio (κendo ) and extrusion rate constant (γ) in synaptic terminals of photoreceptors in retinal slices from tiger salamander. We found that κendo was similar in both cell types-∼25 and 50 in rods and cones, respectively. Using measurements of the decay time constants of Ca2+ transients, we found that γ was also similar, with values of ∼100 s(-1) and 160 s(-1) in rods and cones, respectively. The measurements of κendo differ considerably from measurements in retinal bipolar cells, another ribbon-bearing class of retinal neurons, but are comparable to similar measurements at other conventional synapses. The values of γ are slower than at other synapses, suggesting that Ca2+ ions linger longer in photoreceptor terminals, supporting sustained exocytosis, CICR, and Ca2+ -dependent ribbon replenishment. The mechanisms of endogenous Ca2+ handling in photoreceptors are thus well-suited for supporting tonic neurotransmission. Similarities between rod and cone Ca2+ handling suggest that neither buffering nor extrusion underlie differences in synaptic transmission kinetics.
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Affiliation(s)
- Matthew J Van Hook
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, 68198
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23
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Global Ca2+ signaling drives ribbon-independent synaptic transmission at rod bipolar cell synapses. J Neurosci 2014; 34:6233-44. [PMID: 24790194 DOI: 10.1523/jneurosci.5324-13.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ribbon-type presynaptic active zones are a hallmark of excitatory retinal synapses, and the ribbon organelle is thought to serve as the organizing point of the presynaptic active zone. Imaging of exocytosis from isolated retinal neurons, however, has revealed ectopic release (i.e., release away from ribbons) in significant quantities. Here, we demonstrate in an in vitro mouse retinal slice preparation that ribbon-independent release from rod bipolar cells activates postsynaptic AMPARs on AII amacrine cells. This form of release appears to draw on a unique, ribbon-independent, vesicle pool. Experimental, anatomical, and computational analyses indicate that it is elicited by a significant, global elevation of intraterminal [Ca(2+)] arising following local buffer saturation. Our observations support the conclusion that ribbon-independent release provides a read-out of the average behavior of all of the active zones in a rod bipolar cell's terminal.
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24
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Castellano-Muñoz M, Ricci AJ. Role of intracellular calcium stores in hair-cell ribbon synapse. Front Cell Neurosci 2014; 8:162. [PMID: 24971053 PMCID: PMC4054790 DOI: 10.3389/fncel.2014.00162] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/28/2014] [Indexed: 11/13/2022] Open
Abstract
Intracellular calcium stores control many neuronal functions such as excitability, gene expression, synaptic plasticity, and synaptic release. Although the existence of calcium stores along with calcium-induced calcium release (CICR) has been demonstrated in conventional and ribbon synapses, functional significance and the cellular mechanisms underlying this role remains unclear. This review summarizes recent experimental evidence identifying contribution of CICR to synaptic transmission and synaptic plasticity in the CNS, retina and inner ear. In addition, the potential role of CICR in the recruitment of vesicles to releasable pools in hair-cell ribbon synapses will be specifically discussed.
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Affiliation(s)
| | - Anthony J Ricci
- Department of Otolaryngology, Stanford University School of Medicine Stanford, CA, USA ; Department of Molecular and Cellular Physiology, Stanford University School of Medicine Stanford, CA, USA
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Dutta Roy R, Stefan MI, Rosenmund C. Biophysical properties of presynaptic short-term plasticity in hippocampal neurons: insights from electrophysiology, imaging and mechanistic models. Front Cell Neurosci 2014; 8:141. [PMID: 24904286 PMCID: PMC4033079 DOI: 10.3389/fncel.2014.00141] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/01/2014] [Indexed: 11/16/2022] Open
Abstract
Hippocampal neurons show different types of short-term plasticity (STP). Some exhibit facilitation of their synaptic responses and others depression. In this review we discuss presynaptic biophysical properties behind heterogeneity in STP in hippocampal neurons such as alterations in vesicle priming and docking, fusion, neurotransmitter filling and vesicle replenishment. We look into what types of information electrophysiology, imaging and mechanistic models have given about the time scales and relative impact of the different properties on STP with an emphasis on the use of mechanistic models as complementary tools to experimental procedures. Taken together this tells us that it is possible for a multitude of different mechanisms to underlie the same STP pattern, even though some are more important in specific cases, and that mechanistic models can be used to integrate the biophysical properties to see which mechanisms are more important in specific cases of STP.
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Affiliation(s)
- Ranjita Dutta Roy
- Department of Medicine Solna, Karolinska Insitutet Stockholm, Sweden ; Neuroscience Research Center (NWFZ), Charite Universitatsmedizin Berlin, Germany
| | - Melanie I Stefan
- Department of Neurobiology, Harvard Medical School Boston, MA, USA
| | - Christian Rosenmund
- Neuroscience Research Center (NWFZ), Charite Universitatsmedizin Berlin, Germany
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Schmitz F. Presynaptic [Ca(2+)] and GCAPs: aspects on the structure and function of photoreceptor ribbon synapses. Front Mol Neurosci 2014; 7:3. [PMID: 24567702 PMCID: PMC3915146 DOI: 10.3389/fnmol.2014.00003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 01/15/2014] [Indexed: 12/21/2022] Open
Abstract
Changes in intracellular calcium ions [Ca2+] play important roles in photoreceptor signaling. Consequently, intracellular [Ca2+] levels need to be tightly controlled. In the light-sensitive outer segments (OS) of photoreceptors, Ca2+ regulates the activity of retinal guanylate cyclases thus playing a central role in phototransduction and light-adaptation by restoring light-induced decreases in cGMP. In the synaptic terminals, changes of intracellular Ca2+ trigger various aspects of neurotransmission. Photoreceptors employ tonically active ribbon synapses that encode light-induced, graded changes of membrane potential into modulation of continuous synaptic vesicle exocytosis. The active zones of ribbon synapses contain large electron-dense structures, synaptic ribbons, that are associated with large numbers of synaptic vesicles. Synaptic coding at ribbon synapses differs from synaptic coding at conventional (phasic) synapses. Recent studies revealed new insights how synaptic ribbons are involved in this process. This review focuses on the regulation of [Ca2+] in presynaptic photoreceptor terminals and on the function of a particular Ca2+-regulated protein, the neuronal calcium sensor protein GCAP2 (guanylate cyclase-activating protein-2) in the photoreceptor ribbon synapse. GCAP2, an EF-hand-containing protein plays multiple roles in the OS and in the photoreceptor synapse. In the OS, GCAP2 works as a Ca2+-sensor within a Ca2+-regulated feedback loop that adjusts cGMP levels. In the photoreceptor synapse, GCAP2 binds to RIBEYE, a component of synaptic ribbons, and mediates Ca2+-dependent plasticity at that site. Possible mechanisms are discussed.
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Affiliation(s)
- Frank Schmitz
- Department of Neuroanatomy, Institute for Anatomy and Cell Biology, Medical School Homburg/Saar, Saarland University Saarland, Germany
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Jonas EA. Contributions of Bcl-xL to acute and long term changes in bioenergetics during neuronal plasticity. Biochim Biophys Acta Mol Basis Dis 2013; 1842:1168-78. [PMID: 24240091 DOI: 10.1016/j.bbadis.2013.11.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 11/05/2013] [Accepted: 11/07/2013] [Indexed: 12/23/2022]
Abstract
Mitochondria manufacture and release metabolites and manage calcium during neuronal activity and synaptic transmission, but whether long term alterations in mitochondrial function contribute to the neuronal plasticity underlying changes in organism behavior patterns is still poorly understood. Although normal neuronal plasticity may determine learning, in contrast a persistent decline in synaptic strength or neuronal excitability may portend neurite retraction and eventual somatic death. Anti-death proteins such as Bcl-xL not only provide neuroprotection at the neuronal soma during cell death stimuli, but also appear to enhance neurotransmitter release and synaptic growth and development. It is proposed that Bcl-xL performs these functions through its ability to regulate mitochondrial release of bioenergetic metabolites and calcium, and through its ability to rapidly alter mitochondrial positioning and morphology. Bcl-xL also interacts with proteins that directly alter synaptic vesicle recycling. Bcl-xL translocates acutely to sub-cellular membranes during neuronal activity to achieve changes in synaptic efficacy. After stressful stimuli, pro-apoptotic cleaved delta N Bcl-xL (ΔN Bcl-xL) induces mitochondrial ion channel activity leading to synaptic depression and this is regulated by caspase activation. During physiological states of decreased synaptic stimulation, loss of mitochondrial Bcl-xL and low level caspase activation occur prior to the onset of long term decline in synaptic efficacy. The degree to which Bcl-xL changes mitochondrial membrane permeability may control the direction of change in synaptic strength. The small molecule Bcl-xL inhibitor ABT-737 has been useful in defining the role of Bcl-xL in synaptic processes. Bcl-xL is crucial to the normal health of neurons and synapses and its malfunction may contribute to neurodegenerative disease.
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Affiliation(s)
- Elizabeth A Jonas
- Dept. of Internal Medicine, P.O. Box 208001, Yale University School of Medicine, New Haven, CT 06520, USA; Dept. of Neurobiology, P.O. Box 208020, Yale University School of Medicine, New Haven, CT 06520, USA.
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Abstract
Photoreceptors are exquisitely adapted to transform light stimuli into electrical signals that modulate neurotransmitter release. These cells are organized into several compartments including the unique outer segment (OS). Its whole function is to absorb light and transduce this signal into a change of membrane potential. Another compartment is the inner segment where much of metabolism and regulation of membrane potential takes place and that connects the OS and synapse. The synapse is the compartment where changes in membrane potentials are relayed to other neurons in the retina via release of neurotransmitter. The composition of the plasma membrane surrounding these compartments varies to accommodate their specific functions. In this chapter, we discuss the organization of the plasma membrane emphasizing the protein composition of each region as it relates to visual signaling. We also point out examples where mutations in these proteins cause visual impairment.
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Affiliation(s)
- Sheila A Baker
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
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