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Liu Y, Lin W, Liu J, Zhu H. Structural and temporal dynamics analysis of neural circuit from 2002 to 2022: A bibliometric analysis. Heliyon 2024; 10:e24649. [PMID: 38298625 PMCID: PMC10828061 DOI: 10.1016/j.heliyon.2024.e24649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 01/05/2024] [Accepted: 01/11/2024] [Indexed: 02/02/2024] Open
Abstract
Background In the pursuit of causal insights into neural circuit functionality, various interventions, including electrical, genetic, and pharmacological approaches, have been applied over recent decades. This study employs a comprehensive bibliometric perspective to explore the field of neural circuits. Methods Reviews and articles on neural circuits were obtained from the Web of Science Core Collection (WOSCC) database on Apr. 12, 2023. In this article, co-authorship analysis, co-occurrence analysis, citation analysis, bibliographic analysis, and co-citation analysis were used to clarify the authors, journals, institutions, countries, topics, and internal associations between them. Results More than 2000 organizations from 52 different countries published 3975 articles in the field of "neural circuit" were used to analysis. Luo liqun emerged as the most prolific author, and Deisseroth Karl garners the highest co-citations (3643). The Journal of Neuroscience leaded in publications, while Nature toped in citations. Chinese Academy of Science recorded the highest article count institutionally, with Stanford University ranking first with 14,350 citations. Since 2020, neurodynamic, anxiety-related mechanisms, and GABAergic neurons have gained prominence, shaping the trajectory of neural circuitry research. Conclusions Our investigation has discerned a paradigmatic reorientation towards neurodynamic processes, anxiety-related mechanisms, and GABAergic neurons within the domain of neural circuit research. This identification intimates a prospective trajectory for the field. In the future, it is imperative for research endeavors to accord priority to the translational application of these discernments, with the aim of materializing tangible clinical solutions.
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Affiliation(s)
- Yuan Liu
- Cancer Research Center Nantong, Affiliated Tumor Hospital of Nantong University, Nantong, China
| | - Wei Lin
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University, Suzhou, China
- Department of Pediatrics, The First Affiliated Hospital of Fujian Medical University, Fujian, China
| | - Jie Liu
- Department of Orthopedics, The Affiliated Taizhou People's Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, China
| | - Haixia Zhu
- Cancer Research Center Nantong, Affiliated Tumor Hospital of Nantong University, Nantong, China
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2
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Dumitrescu AV, Pfeifer WL, Arhens M, Andorf JL, Drack AV. CACNA1F-related synaptic dysfunction: challenges diagnosing congenital stationary night blindness presenting without night blindness. CANADIAN JOURNAL OF OPHTHALMOLOGY 2023:S0008-4182(23)00382-4. [PMID: 38159912 DOI: 10.1016/j.jcjo.2023.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 11/26/2023] [Indexed: 01/03/2024]
Abstract
OBJECTIVE To describe pediatric patients with CACNA1F-associated incomplete X-linked congenital stationary night blindness presenting without nyctalopia, and review the causes leading to diagnosis delay. DESIGN Retrospective cohort. METHODS This was set in a single institution between 2004 and 2019. There were12 patients. The intervention or observation procedures used were clinical course, visual acuity, refractive error, images, electrophysiology, genetic testing, pedigree. The main outcome measures were cohort description and causes of diagnosis delay. RESULTS For these 12 cases, the referring diagnosis was congenital nystagmus (7), reduced best-corrected visual acuity (BCVA, 4), and progressive myopia (1). Nyctalopia was not a presenting symptom and developed in 4 patients during follow-up. Seven patients presented with nystagmus. All patients developed early-onset myopia. Myopia progressed more rapidly before age 6 than after (average 1.14 D vs 0.25 D) (p = 0.0033). The average final BCVA was 20/50 (20/30-20/150). Vision at presentation was correlated with final visual acuity (r2 = 0.87, p = 5.4E-06). The first cycloplegic refraction was correlated to the final refractive error (r2 = 0.49, p = 0.009). Patients with nystagmus had worse BCVA on average. Full-field electroretinogram was abnormal and diagnostic in all cases, as confirmed by genetic testing. The average time to diagnosis was 4.2 years, and the average age at diagnosis was 7.9 years. The delay in diagnosis was due to the absence of nyctalopia, not performing an electroretinogram and/or an alternative diagnosis. CONCLUSIONS In children, CACNA1F-associated synaptic dysfunction does not usually present with night blindness. It should be suspected in male patients with early-onset myopia, especially with a history of nystagmus.
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Affiliation(s)
| | - Wanda L Pfeifer
- Department of Ophthalmology, University of Iowa, Iowa City, Iowa
| | - Monica Arhens
- Department of Biostatistics, University of Iowa, Iowa City, Iowa
| | - Jeaneen L Andorf
- Institute for Vision Research, University of Iowa, Iowa City, Iowa
| | - Arlene V Drack
- Department of Ophthalmology, University of Iowa, Iowa City, Iowa; Department of Biostatistics, University of Iowa, Iowa City, Iowa
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3
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Nijboer TCW, Hessel EVS, van Haaften GW, van Zandvoort MJ, van der Spek PJ, Troelstra C, de Kovel CGF, Koeleman BPC, van der Zwaag B, Brilstra EH, Burbach JPH. Identification of candidate genes for developmental colour agnosia in a single unique family. PLoS One 2023; 18:e0290013. [PMID: 37672513 PMCID: PMC10482254 DOI: 10.1371/journal.pone.0290013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 07/31/2023] [Indexed: 09/08/2023] Open
Abstract
Colour agnosia is a disorder that impairs colour knowledge (naming, recognition) despite intact colour perception. Previously, we have identified the first and only-known family with hereditary developmental colour agnosia. The aim of the current study was to explore genomic regions and candidate genes that potentially cause this trait in this family. For three family members with developmental colour agnosia and three unaffected family members CGH-array analysis and exome sequencing was performed, and linkage analysis was carried out using DominantMapper, resulting in the identification of 19 cosegregating chromosomal regions. Whole exome sequencing resulted in 11 rare coding variants present in all affected family members with developmental colour agnosia and absent in unaffected members. These variants affected genes that have been implicated in neural processes and functions (CACNA2D4, DDX25, GRINA, MYO15A) or that have an indirect link to brain function, development or disease (MAML2, STAU1, TMED3, RABEPK), and a remaining group lacking brain expression or involved in non-neural traits (DEPDC7, OR1J1, OR8D4). Although this is an explorative study, the small set of candidate genes that could serve as a starting point for unravelling mechanisms of higher level cognitive functions and cortical specialization, and disorders therein such as developmental colour agnosia.
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Affiliation(s)
- Tanja C. W. Nijboer
- UMCU Brain Center and Center of Excellence for Rehabilitation Medicine, University Medical Center Utrecht and De Hoogstraat Rehabilitation, Utrecht, The Netherlands
- Department of Experimental Psychology and Helmholtz Institute, Utrecht University, Utrecht, The Netherlands
| | - Ellen V. S. Hessel
- UMCU Brain Center and Center of Excellence for Rehabilitation Medicine, University Medical Center Utrecht and De Hoogstraat Rehabilitation, Utrecht, The Netherlands
- Department of Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Gijs W. van Haaften
- Department of Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Martine J. van Zandvoort
- Department of Experimental Psychology and Helmholtz Institute, Utrecht University, Utrecht, The Netherlands
| | - Peter J. van der Spek
- Department of Pathology, Erasmus Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Christine Troelstra
- Department of Pathology, Erasmus Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Carolien G. F. de Kovel
- Department of Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bobby P. C. Koeleman
- Department of Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bert van der Zwaag
- Department of Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Eva H. Brilstra
- Department of Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - J. Peter H. Burbach
- UMCU Brain Center, Department of Translational Neuroscience, University Medical Center Utrecht, Utrecht, the Netherlands
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4
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Laird JG, Kopel A, Lankford CK, Baker SA. Mouse all-cone retina models of Cav1.4 synaptopathy. Front Mol Neurosci 2023; 16:1155955. [PMID: 37181655 PMCID: PMC10174292 DOI: 10.3389/fnmol.2023.1155955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/03/2023] [Indexed: 05/16/2023] Open
Abstract
The voltage-gated calcium channel, Cav1.4 is localized to photoreceptor ribbon synapses and functions both in molecular organization of the synapse and in regulating release of synaptic vesicles. Mutations in Cav1.4 subunits typically present as either incomplete congenital stationary night blindness or a progressive cone-rod dystrophy in humans. We developed a cone-rich mammalian model system to further study how different Cav1.4 mutations affect cones. RPE65 R91W KI; Nrl KO "Conefull" mice were crossed to Cav1.4 α1F or α2δ4 KO mice to generate the "Conefull:α1F KO" and "Conefull:α2δ4 KO" lines. Animals were assessed using a visually guided water maze, electroretinogram (ERG), optical coherence tomography (OCT), and histology. Mice of both sexes and up to six-months of age were used. Conefull: α1F KO mice could not navigate the visually guided water maze, had no b-wave in the ERG, and the developing all-cone outer nuclear layer reorganized into rosettes at the time of eye opening with degeneration progressing to 30% loss by 2-months of age. In comparison, the Conefull: α2δ4 KO mice successfully navigated the visually guided water maze, had a reduced amplitude b-wave ERG, and the development of the all-cone outer nuclear layer appeared normal although progressive degeneration with 10% loss by 2-months of age was observed. In summary, new disease models for studying congenital synaptic diseases due to loss of Cav1.4 function have been created.
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Affiliation(s)
| | | | | | - Sheila A. Baker
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA, United States
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5
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Gregg RG, Hasan N, Borghuis BG. LRIT3 expression in cone photoreceptors restores post-synaptic bipolar cell signalplex assembly and partial function in Lrit3 -/- mice. iScience 2023; 26:106499. [PMID: 37091241 PMCID: PMC10113827 DOI: 10.1016/j.isci.2023.106499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 12/20/2022] [Accepted: 03/22/2023] [Indexed: 04/25/2023] Open
Abstract
Complete congenital stationary night blindness (cCSNB) is a heterogeneous disorder characterized by poor dim-light vision, myopia, and nystagmus that is caused by mutations in genes critical for signal transmission between photoreceptors and depolarizing bipolar cells (DBCs). One such gene, LRIT3, is required for assembly of the post-synaptic signaling complex (signalplex) at the dendritic tips of DBCs, although the number of signalplex components impacted is greater in cone DBCs (all components) than in rod bipolar cells (only TRPM1 and Nyctalopin). Here we show that rAAV-mediated expression of LRIT3 in cones results in robust rescue of cone DBC signalplex components and partially restores downstream visual function, as measured by the light-adapted electroretinogram (ERG) b-wave and electrophysiological recordings of bipolar cells (BCs) and RGCs. These data show that LRIT3 successfully restores partial function to cone DBCs most likely in a trans-synaptic manner, potentially paving the way for therapeutic intervention in LRIT3-associated cCSNB.
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Affiliation(s)
- Ronald G. Gregg
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292, USA
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40292, USA
- Corresponding author
| | - Nazarul Hasan
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292, USA
| | - Bart G. Borghuis
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292, USA
- Corresponding author
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6
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Cunningham KL, Littleton JT. Mechanisms controlling the trafficking, localization, and abundance of presynaptic Ca 2+ channels. Front Mol Neurosci 2023; 15:1116729. [PMID: 36710932 PMCID: PMC9880069 DOI: 10.3389/fnmol.2022.1116729] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 12/26/2022] [Indexed: 01/14/2023] Open
Abstract
Voltage-gated Ca2+ channels (VGCCs) mediate Ca2+ influx to trigger neurotransmitter release at specialized presynaptic sites termed active zones (AZs). The abundance of VGCCs at AZs regulates neurotransmitter release probability (Pr ), a key presynaptic determinant of synaptic strength. Given this functional significance, defining the processes that cooperate to establish AZ VGCC abundance is critical for understanding how these mechanisms set synaptic strength and how they might be regulated to control presynaptic plasticity. VGCC abundance at AZs involves multiple steps, including channel biosynthesis (transcription, translation, and trafficking through the endomembrane system), forward axonal trafficking and delivery to synaptic terminals, incorporation and retention at presynaptic sites, and protein recycling. Here we discuss mechanisms that control VGCC abundance at synapses, highlighting findings from invertebrate and vertebrate models.
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Affiliation(s)
- Karen L. Cunningham
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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7
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Inamdar SM, Lankford CK, Baker SA. Photoreceptor Ion Channels in Signaling and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:269-276. [PMID: 37440044 DOI: 10.1007/978-3-031-27681-1_39] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Photoreceptors (PRs) in the neural retina convert photon capture into an electrical signal that is communicated across a chemical synapse to second-order neurons in the retina and on through the rest of the visual pathway. This information is decoded in the visual cortex to create images. The activity of PRs depends on the concerted action of several voltage-gated ion channels that will be discussed in this chapter.
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Affiliation(s)
- Shivangi M Inamdar
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA, USA.
| | - Colten K Lankford
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA, USA
| | - Sheila A Baker
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA, USA
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8
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Depleted Calcium Stores and Increased Calcium Entry in Rod Photoreceptors of the Cacna2d4 Mouse Model of Cone-Rod Dystrophy RCD4. Int J Mol Sci 2022; 23:ijms232113080. [DOI: 10.3390/ijms232113080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/17/2022] [Accepted: 10/21/2022] [Indexed: 11/16/2022] Open
Abstract
Unidentified pathogenetic mechanisms and genetic and clinical heterogeneity represent critical factors hindering the development of treatments for inherited retinal dystrophies. Frameshift mutations in Cacna2d4, which codes for an accessory subunit of voltage-gated calcium channels (VGCC), cause cone-rod dystrophy RCD4 in patients, but the underlying mechanisms remain unknown. To define its pathogenetic mechanisms, we investigated the impact of a Cacna2d4 frameshift mutation on the electrophysiological profile and calcium handling of mouse rod photoreceptors by patch-clamp recordings and calcium imaging, respectively. In mutant (MUT) rods, the dysregulation of calcium handling extends beyond the reduction in calcium entry through VGCC and surprisingly involves internal calcium stores’ depletion and upregulation of calcium entry via non-selective cationic channels (CSC). The similar dependence of CSC on basal calcium levels in WT and MUT rods suggests that the primary defect in MUT rods lies in defective calcium stores. Calcium stores’ depletion, leading to upregulated calcium and sodium influx via CSC, represents a novel and, so far, unsuspected consequence of the Cacna2d4 mutation. Blocking CSC may provide a novel strategy to counteract the well-known pathogenetic mechanisms involved in rod demise, such as the reticulum stress response and calcium and sodium overload due to store depletion.
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9
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Abstract
Voltage-gated Ca2+ (Cav) channels play pivotal roles in regulating gene transcription, neuronal excitability, and neurotransmitter release. To meet the spatial and temporal demands of visual signaling, Cav channels exhibit unusual properties in the retina compared to their counterparts in other areas of the nervous system. In this article, we review current concepts regarding the specific subtypes of Cav channels expressed in the retina, their intrinsic properties and forms of modulation, and how their dysregulation could lead to retinal disease.
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Affiliation(s)
- Brittany Williams
- Department of Cell Biology & Physiology, Carolina Institute for Developmental Disabilities, and Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina, USA
| | - J Wesley Maddox
- Department of Neuroscience, University of Texas, Austin, Texas, USA;
| | - Amy Lee
- Department of Neuroscience, University of Texas, Austin, Texas, USA;
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10
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Campla CK, Bocchero U, Strickland R, Nellissery J, Advani J, Ignatova I, Srivastava D, Aponte AM, Wang Y, Gumerson J, Martemyanov K, Artemyev NO, Pahlberg J, Swaroop A. Frmpd1 Facilitates Trafficking of G-Protein Transducin and Modulates Synaptic Function in Rod Photoreceptors of Mammalian Retina. eNeuro 2022; 9:ENEURO.0348-22.2022. [PMID: 36180221 PMCID: PMC9581579 DOI: 10.1523/eneuro.0348-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 09/23/2022] [Indexed: 12/15/2022] Open
Abstract
Trafficking of transducin (Gαt) in rod photoreceptors is critical for adaptive and modulatory responses of the retina to varying light intensities. In addition to fine-tuning phototransduction gain in rod outer segments (OSs), light-induced translocation of Gαt to the rod synapse enhances rod to rod bipolar synaptic transmission. Here, we show that the rod-specific loss of Frmpd1 (FERM and PDZ domain containing 1), in the retina of both female and male mice, results in delayed return of Gαt from the synapse back to outer segments in the dark, compromising the capacity of rods to recover from light adaptation. Frmpd1 directly interacts with Gpsm2 (G-protein signaling modulator 2), and the two proteins are required for appropriate sensitization of rod-rod bipolar signaling under saturating light conditions. These studies provide insight into how the trafficking and function of Gαt is modulated to optimize the photoresponse and synaptic transmission of rod photoreceptors in a light-dependent manner.
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Affiliation(s)
- Christie K Campla
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
| | - Ulisse Bocchero
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
- Photoreceptor Physiology Group, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
| | - Ryan Strickland
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jacob Nellissery
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jayshree Advani
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
| | - Irina Ignatova
- Photoreceptor Physiology Group, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
| | - Dhiraj Srivastava
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Angel M Aponte
- Proteomics Core, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yuchen Wang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458
| | - Jessica Gumerson
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
| | - Kirill Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA 52242
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Johan Pahlberg
- Photoreceptor Physiology Group, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892
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11
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Ablinger C, Eibl C, Geisler SM, Campiglio M, Stephens GJ, Missler M, Obermair GJ. α 2δ-4 and Cachd1 Proteins Are Regulators of Presynaptic Functions. Int J Mol Sci 2022; 23:9885. [PMID: 36077281 PMCID: PMC9456004 DOI: 10.3390/ijms23179885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/15/2022] [Accepted: 08/24/2022] [Indexed: 11/17/2022] Open
Abstract
The α2δ auxiliary subunits of voltage-gated calcium channels (VGCC) were traditionally regarded as modulators of biophysical channel properties. In recent years, channel-independent functions of these subunits, such as involvement in synapse formation, have been identified. In the central nervous system, α2δ isoforms 1, 2, and 3 are strongly expressed, regulating glutamatergic synapse formation by a presynaptic mechanism. Although the α2δ-4 isoform is predominantly found in the retina with very little expression in the brain, it was recently linked to brain functions. In contrast, Cachd1, a novel α2δ-like protein, shows strong expression in brain, but its function in neurons is not yet known. Therefore, we aimed to investigate the presynaptic functions of α2δ-4 and Cachd1 by expressing individual proteins in cultured hippocampal neurons. Both α2δ-4 and Cachd1 are expressed in the presynaptic membrane and could rescue a severe synaptic defect present in triple knockout/knockdown neurons that lacked the α2δ-1-3 isoforms (α2δ TKO/KD). This observation suggests that presynaptic localization and the regulation of synapse formation in glutamatergic neurons is a general feature of α2δ proteins. In contrast to this redundant presynaptic function, α2δ-4 and Cachd1 differentially regulate the abundance of presynaptic calcium channels and the amplitude of presynaptic calcium transients. These functional differences may be caused by subtle isoform-specific differences in α1-α2δ protein-protein interactions, as revealed by structural homology modelling. Taken together, our study identifies both α2δ-4 and Cachd1 as presynaptic regulators of synapse formation, differentiation, and calcium channel functions that can at least partially compensate for the loss of α2δ-1-3. Moreover, we show that regulating glutamatergic synapse formation and differentiation is a critical and surprisingly redundant function of α2δ and Cachd1.
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Affiliation(s)
- Cornelia Ablinger
- Institute of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Clarissa Eibl
- Division Physiology, Department of Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, 3500 Krems, Austria
| | - Stefanie M. Geisler
- Department Pharmacology and Toxicology, University of Innsbruck, 6020 Innsbruck, Austria
| | - Marta Campiglio
- Institute of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Gary J. Stephens
- Reading School of Pharmacy, University of Reading, Reading RG6 6UB, UK
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Gerald J. Obermair
- Institute of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
- Division Physiology, Department of Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, 3500 Krems, Austria
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12
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Klomp A, Omichi R, Iwasa Y, Smith RJ, Usachev YM, Russo AF, Narayanan NS, Lee A. The voltage-gated Ca2+ channel subunit α2δ-4 regulates locomotor behavior and sensorimotor gating in mice. PLoS One 2022; 17:e0263197. [PMID: 35353835 PMCID: PMC8967030 DOI: 10.1371/journal.pone.0263197] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 03/11/2022] [Indexed: 01/06/2023] Open
Abstract
Voltage-gated Ca2+ channels are critical for the development and mature function of the nervous system. Variants in the CACNA2D4 gene encoding the α2δ-4 auxiliary subunit of these channels are associated with neuropsychiatric and neurodevelopmental disorders. α2δ-4 is prominently expressed in the retina and is crucial for vision, but extra-retinal functions of α2δ-4 have not been investigated. Here, we sought to fill this gap by analyzing the behavioral phenotypes of α2δ-4 knockout (KO) mice. α2δ-4 KO mice (both males and females) exhibited significant impairments in prepulse inhibition that were unlikely to result from the modestly elevated auditory brainstem response thresholds. Whereas α2δ-4 KO mice of both sexes were hyperactive in various assays, only females showed impaired motor coordination in the rotarod assay. α2δ-4 KO mice exhibited anxiolytic and anti-depressive behaviors in the elevated plus maze and tail suspension tests, respectively. Our results reveal an unexpected role for α2δ-4 in sensorimotor gating and motor function and identify α2δ-4 KO mice as a novel model for studying the pathophysiology associated with CACNA2D4 variants.
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Affiliation(s)
- Annette Klomp
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, Iowa, United States of America
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, United States of America
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, United States of America
| | - Ryotaro Omichi
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, United States of America
- Iowa Institute of Human Genetics, University of Iowa, Iowa City, Iowa, United States of America
| | - Yoichiro Iwasa
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, United States of America
- Iowa Institute of Human Genetics, University of Iowa, Iowa City, Iowa, United States of America
| | - Richard J. Smith
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, United States of America
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, United States of America
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, United States of America
- Iowa Institute of Human Genetics, University of Iowa, Iowa City, Iowa, United States of America
| | - Yuriy M. Usachev
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, United States of America
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, Iowa, United States of America
| | - Andrew F. Russo
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, United States of America
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, United States of America
- Department of Neurology, University of Iowa, Iowa City, Iowa, United States of America
| | - Nandakumar S. Narayanan
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, United States of America
- Department of Neurology, University of Iowa, Iowa City, Iowa, United States of America
| | - Amy Lee
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, United States of America
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, United States of America
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, United States of America
- Department of Neurology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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13
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Adhesion GPCR Latrophilin 3 regulates synaptic function of cone photoreceptors in a trans-synaptic manner. Proc Natl Acad Sci U S A 2021; 118:2106694118. [PMID: 34732574 DOI: 10.1073/pnas.2106694118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2021] [Indexed: 12/15/2022] Open
Abstract
Cone photoreceptors mediate daylight vision in vertebrates. Changes in neurotransmitter release at cone synapses encode visual information and is subject to precise control by negative feedback from enigmatic horizontal cells. However, the mechanisms that orchestrate this modulation are poorly understood due to a virtually unknown landscape of molecular players. Here, we report a molecular player operating selectively at cone synapses that modulates effects of horizontal cells on synaptic release. Using an unbiased proteomic screen, we identified an adhesion GPCR Latrophilin3 (LPHN3) in horizontal cell dendrites that engages in transsynaptic control of cones. We detected and characterized a prominent splice isoform of LPHN3 that excludes a element with inhibitory influence on transsynaptic interactions. A gain-of-function mouse model specifically routing LPHN3 splicing to this isoform but not knockout of LPHN3 diminished CaV1.4 calcium channel activity profoundly disrupted synaptic release by cones and resulted in synaptic transmission deficits. These findings offer molecular insight into horizontal cell modulation on cone synaptic function and more broadly demonstrate the importance of alternative splicing in adhesion GPCRs for their physiological function.
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14
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Bharathan SP, Ferrario A, Stepanian K, Fernandez GE, Reid MW, Kim JS, Hutchens C, Harutyunyan N, Marks C, Thornton ME, Grubbs BH, Cobrinik D, Aparicio JG, Nagiel A. Characterization and staging of outer plexiform layer development in human retina and retinal organoids. Development 2021; 148:272710. [PMID: 34738615 DOI: 10.1242/dev.199551] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 10/26/2021] [Indexed: 11/20/2022]
Abstract
The development of the first synapse of the visual system between photoreceptors and bipolar cells in the outer plexiform layer (OPL) of the human retina is critical for visual processing but poorly understood. By studying the maturation state and spatial organization of photoreceptors, depolarizing bipolar cells, and horizontal cells in the human fetal retina, we establish a pseudo-temporal staging system for OPL development that we term OPL-Stages 0 to 4. This was validated through quantification of increasingly precise subcellular localization of Bassoon to the OPL with each stage (p<0.0001). By applying these OPL staging criteria to human retinal organoids (HROs) derived from human embryonic and induced pluripotent stem cells, we observed comparable maturation from OPL-Stage 0 at day 100 in culture up to OPL-Stage 3 by day 160. Quantification of presynaptic protein localization confirmed progression from OPL-Stage 0 to 3 (p<0.0001). Overall, this study defines stages of human OPL development through mid-gestation and establishes HROs as a model system that recapitulates key aspects of human photoreceptor-bipolar cell synaptogenesis in vitro.
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Affiliation(s)
- Sumitha Prameela Bharathan
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Angela Ferrario
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Kayla Stepanian
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - G Esteban Fernandez
- The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Mark W Reid
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Justin S Kim
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Chloe Hutchens
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Narine Harutyunyan
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Carolyn Marks
- Core Center of Excellence in Nano Imaging, University of Southern California, Los Angeles, CA, USA
| | - Matthew E Thornton
- Maternal-Fetal Medicine Division, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Brendan H Grubbs
- Maternal-Fetal Medicine Division, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - David Cobrinik
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA.,Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.,Department of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.,Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jennifer G Aparicio
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Aaron Nagiel
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA.,Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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15
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Andreazzoli M, Barravecchia I, De Cesari C, Angeloni D, Demontis GC. Inducible Pluripotent Stem Cells to Model and Treat Inherited Degenerative Diseases of the Outer Retina: 3D-Organoids Limitations and Bioengineering Solutions. Cells 2021; 10:cells10092489. [PMID: 34572137 PMCID: PMC8471616 DOI: 10.3390/cells10092489] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/12/2021] [Accepted: 09/15/2021] [Indexed: 12/12/2022] Open
Abstract
Inherited retinal degenerations (IRD) affecting either photoreceptors or pigment epithelial cells cause progressive visual loss and severe disability, up to complete blindness. Retinal organoids (ROs) technologies opened up the development of human inducible pluripotent stem cells (hiPSC) for disease modeling and replacement therapies. However, hiPSC-derived ROs applications to IRD presently display limited maturation and functionality, with most photoreceptors lacking well-developed outer segments (OS) and light responsiveness comparable to their adult retinal counterparts. In this review, we address for the first time the microenvironment where OS mature, i.e., the subretinal space (SRS), and discuss SRS role in photoreceptors metabolic reprogramming required for OS generation. We also address bioengineering issues to improve culture systems proficiency to promote OS maturation in hiPSC-derived ROs. This issue is crucial, as satisfying the demanding metabolic needs of photoreceptors may unleash hiPSC-derived ROs full potential for disease modeling, drug development, and replacement therapies.
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Affiliation(s)
| | - Ivana Barravecchia
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy;
- Institute of Life Sciences, Scuola Superiore Sant’Anna, 56124 Pisa, Italy;
| | | | - Debora Angeloni
- Institute of Life Sciences, Scuola Superiore Sant’Anna, 56124 Pisa, Italy;
| | - Gian Carlo Demontis
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy;
- Correspondence: (M.A.); (G.C.D.)
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16
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Koschak A, Fernandez-Quintero ML, Heigl T, Ruzza M, Seitter H, Zanetti L. Cav1.4 dysfunction and congenital stationary night blindness type 2. Pflugers Arch 2021; 473:1437-1454. [PMID: 34212239 PMCID: PMC8370969 DOI: 10.1007/s00424-021-02570-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/14/2021] [Accepted: 04/18/2021] [Indexed: 12/04/2022]
Abstract
Cav1.4 L-type Ca2+ channels are predominantly expressed in retinal neurons, particularly at the photoreceptor terminals where they mediate sustained Ca2+ entry needed for continuous neurotransmitter release at their ribbon synapses. Cav1.4 channel gating properties are controlled by accessory subunits, associated regulatory proteins, and also alternative splicing. In humans, mutations in the CACNA1F gene encoding for Cav1.4 channels are associated with X-linked retinal disorders such as congenital stationary night blindness type 2. Mutations in the Cav1.4 protein result in a spectrum of altered functional channel activity. Several mouse models broadened our understanding of the role of Cav1.4 channels not only as Ca2+ source at retinal synapses but also as synaptic organizers. In this review, we highlight different structural and functional phenotypes of Cav1.4 mutations that might also occur in patients with congenital stationary night blindness type 2. A further important yet mostly neglected aspect that we discuss is the influence of alternative splicing on channel dysfunction. We conclude that currently available functional phenotyping strategies should be refined and summarize potential specific therapeutic options for patients carrying Cav1.4 mutations. Importantly, the development of new therapeutic approaches will permit a deeper understanding of not only the disease pathophysiology but also the physiological function of Cav1.4 channels in the retina.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Calcium Channel Agonists/pharmacology
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Eye Diseases, Hereditary/genetics
- Eye Diseases, Hereditary/metabolism
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/metabolism
- Humans
- Mutation/physiology
- Myopia/genetics
- Myopia/metabolism
- Night Blindness/genetics
- Night Blindness/metabolism
- Retina/drug effects
- Retina/metabolism
- Synapses/drug effects
- Synapses/genetics
- Synapses/metabolism
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Affiliation(s)
- Alexandra Koschak
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria.
| | - Monica L Fernandez-Quintero
- Institute of General, Inorganic and Theoretical Chemistry, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
| | - Thomas Heigl
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
| | - Marco Ruzza
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
| | - Hartwig Seitter
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
| | - Lucia Zanetti
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
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17
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Ryl M, Urbasik A, Gierke K, Babai N, Joachimsthaler A, Feigenspan A, Frischknecht R, Stallwitz N, Fejtová A, Kremers J, von Wittgenstein J, Brandstätter JH. Genetic disruption of bassoon in two mutant mouse lines causes divergent retinal phenotypes. FASEB J 2021; 35:e21520. [PMID: 33811381 DOI: 10.1096/fj.202001962r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 02/19/2021] [Accepted: 02/26/2021] [Indexed: 11/11/2022]
Abstract
Bassoon (BSN) is a presynaptic cytomatrix protein ubiquitously present at chemical synapses of the central nervous system, where it regulates synaptic vesicle replenishment and organizes voltage-gated Ca2+ channels. In sensory photoreceptor synapses, BSN additionally plays a decisive role in anchoring the synaptic ribbon, a presynaptic organelle and functional extension of the active zone, to the presynaptic membrane. In this study, we functionally and structurally analyzed two mutant mouse lines with a genetic disruption of Bsn-Bsngt and Bsnko -using electrophysiology and high-resolution microscopy. In both Bsn mutant mouse lines, full-length BSN was abolished, and photoreceptor synaptic function was similarly impaired, yet synapse structure was more severely affected in Bsngt/gt than in Bsnko/ko photoreceptors. The synaptic defects in Bsngt/gt retina coincide with remodeling of the outer retina-rod bipolar and horizontal cell sprouting, formation of ectopic ribbon synaptic sites-and death of cone photoreceptors, processes that did not occur in Bsnko/ko retina. An analysis of Bsngt/ko hybrid mice revealed that the divergent retinal phenotypes of Bsngt/gt and Bsnko/ko mice can be attributed to the expression of the Bsngt allele, which triggers cone photoreceptor death and neurite sprouting in the outer retina. These findings shed new light on the existing Bsn mutant mouse models and might help to understand mechanisms that drive photoreceptor death.
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Affiliation(s)
- Miriam Ryl
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Alexander Urbasik
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Kaspar Gierke
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Norbert Babai
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anneka Joachimsthaler
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Feigenspan
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Renato Frischknecht
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Nina Stallwitz
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anna Fejtová
- Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jan Kremers
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Julia von Wittgenstein
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Johann Helmut Brandstätter
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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18
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Petralia RS, Yao PJ, Kapogiannis D, Wang YX. Invaginating Structures in Synapses - Perspective. Front Synaptic Neurosci 2021; 13:685052. [PMID: 34108873 PMCID: PMC8180840 DOI: 10.3389/fnsyn.2021.685052] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 04/28/2021] [Indexed: 01/05/2023] Open
Abstract
Invaginating structures are common in the synapses of most animals. However, the details of these invaginating structures remain understudied in part because they are not well resolved in light microscopy and were often misidentified in early electron microscope (EM) studies. Utilizing experimental techniques along with the latest advances in microscopy, such as focused ion beam-scanning EM (FIB-SEM), evidence is gradually building to suggest that the synaptic invaginating structures contribute to synapse development, maintenance, and plasticity. These invaginating structures are most elaborate in synapses mediating rapid integration of signals, such as muscle contraction, mechanoreception, and vision. Here we argue that the synaptic invaginations should be considered in future studies seeking to understand their role in sensory integration and coordination, learning, and memory. We review the various types of invaginating structures in the synapses and discuss their potential functions. We also present several new examples of invaginating structures from a variety of animals including Drosophila and mice, mainly using FIB-SEM, with which we trace the form and arrangement of these structures.
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Affiliation(s)
- Ronald S. Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders/National Institutes of Health, Bethesda, MD, United States
| | - Pamela J. Yao
- Laboratory of Clinical Investigation, National Institute on Aging/National Institutes of Health, Bethesda, MD, United States
| | - Dimitrios Kapogiannis
- Laboratory of Clinical Investigation, National Institute on Aging/National Institutes of Health, Bethesda, MD, United States
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders/National Institutes of Health, Bethesda, MD, United States
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19
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Schöpf CL, Ablinger C, Geisler SM, Stanika RI, Campiglio M, Kaufmann WA, Nimmervoll B, Schlick B, Brockhaus J, Missler M, Shigemoto R, Obermair GJ. Presynaptic α 2δ subunits are key organizers of glutamatergic synapses. Proc Natl Acad Sci U S A 2021; 118:e1920827118. [PMID: 33782113 PMCID: PMC8040823 DOI: 10.1073/pnas.1920827118] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In nerve cells the genes encoding for α2δ subunits of voltage-gated calcium channels have been linked to synaptic functions and neurological disease. Here we show that α2δ subunits are essential for the formation and organization of glutamatergic synapses. Using a cellular α2δ subunit triple-knockout/knockdown model, we demonstrate a failure in presynaptic differentiation evidenced by defective presynaptic calcium channel clustering and calcium influx, smaller presynaptic active zones, and a strongly reduced accumulation of presynaptic vesicle-associated proteins (synapsin and vGLUT). The presynaptic defect is associated with the downscaling of postsynaptic AMPA receptors and the postsynaptic density. The role of α2δ isoforms as synaptic organizers is highly redundant, as each individual α2δ isoform can rescue presynaptic calcium channel trafficking and expression of synaptic proteins. Moreover, α2δ-2 and α2δ-3 with mutated metal ion-dependent adhesion sites can fully rescue presynaptic synapsin expression but only partially calcium channel trafficking, suggesting that the regulatory role of α2δ subunits is independent from its role as a calcium channel subunit. Our findings influence the current view on excitatory synapse formation. First, our study suggests that postsynaptic differentiation is secondary to presynaptic differentiation. Second, the dependence of presynaptic differentiation on α2δ implicates α2δ subunits as potential nucleation points for the organization of synapses. Finally, our results suggest that α2δ subunits act as transsynaptic organizers of glutamatergic synapses, thereby aligning the synaptic active zone with the postsynaptic density.
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Affiliation(s)
- Clemens L Schöpf
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Cornelia Ablinger
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Stefanie M Geisler
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
- Department of Pharmacology and Toxicology, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Ruslan I Stanika
- Division of Physiology, Karl Landsteiner University of Health Sciences, A-3500 Krems, Austria
| | - Marta Campiglio
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Walter A Kaufmann
- Institute of Science and Technology Austria, A-3400 Klosterneuburg, Austria
| | - Benedikt Nimmervoll
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Bettina Schlick
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Johannes Brockhaus
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms University, 48149 Münster, Germany
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms University, 48149 Münster, Germany
| | - Ryuichi Shigemoto
- Institute of Science and Technology Austria, A-3400 Klosterneuburg, Austria
| | - Gerald J Obermair
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria;
- Division of Physiology, Karl Landsteiner University of Health Sciences, A-3500 Krems, Austria
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20
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Thoreson WB. Transmission at rod and cone ribbon synapses in the retina. Pflugers Arch 2021; 473:1469-1491. [PMID: 33779813 DOI: 10.1007/s00424-021-02548-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/23/2021] [Accepted: 02/25/2021] [Indexed: 12/29/2022]
Abstract
Light-evoked voltage responses of rod and cone photoreceptor cells in the vertebrate retina must be converted to a train of synaptic vesicle release events for transmission to downstream neurons. This review discusses the processes, proteins, and structures that shape this critical early step in vision, focusing on studies from salamander retina with comparisons to other experimental animals. Many mechanisms are conserved across species. In cones, glutamate release is confined to ribbon release sites although rods are also capable of release at non-ribbon sites. The role of non-ribbon release in rods remains unclear. Release from synaptic ribbons in rods and cones involves at least three vesicle pools: a readily releasable pool (RRP) matching the number of membrane-associated vesicles along the ribbon base, a ribbon reserve pool matching the number of additional vesicles on the ribbon, and an enormous cytoplasmic reserve. Vesicle release increases in parallel with Ca2+ channel activity. While the opening of only a few Ca2+ channels beneath each ribbon can trigger fusion of a single vesicle, sustained release rates in darkness are governed by the rate at which the RRP can be replenished. The number of vacant release sites, their functional status, and the rate of vesicle delivery in turn govern replenishment. Along with an overview of the mechanisms of exocytosis and endocytosis, we consider specific properties of ribbon-associated proteins and pose a number of remaining questions about this first synapse in the visual system.
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Affiliation(s)
- Wallace B Thoreson
- Truhlsen Eye Institute, Departments of Ophthalmology & Visual Sciences and Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
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21
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Geisler SM, Benedetti A, Schöpf CL, Schwarzer C, Stefanova N, Schwartz A, Obermair GJ. Phenotypic Characterization and Brain Structure Analysis of Calcium Channel Subunit α 2δ-2 Mutant (Ducky) and α 2δ Double Knockout Mice. Front Synaptic Neurosci 2021; 13:634412. [PMID: 33679366 PMCID: PMC7933509 DOI: 10.3389/fnsyn.2021.634412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 01/11/2021] [Indexed: 01/19/2023] Open
Abstract
Auxiliary α2δ subunits of voltage-gated calcium channels modulate channel trafficking, current properties, and synapse formation. Three of the four isoforms (α2δ-1, α2δ-2, and α2δ-3) are abundantly expressed in the brain; however, of the available knockout models, only α2δ-2 knockout or mutant mice display an obvious abnormal neurological phenotype. Thus, we hypothesize that the neuronal α2δ isoforms may have partially specific as well as redundant functions. To address this, we generated three distinct α2δ double knockout mouse models by crossbreeding single knockout (α2δ-1 and -3) or mutant (α2δ-2/ducky) mice. Here, we provide a first phenotypic description and brain structure analysis. We found that genotypic distribution of neonatal litters in distinct α2δ-1/-2, α2δ-1/-3, and α2δ-2/-3 breeding combinations did not conform to Mendel's law, suggesting premature lethality of single and double knockout mice. Notably, high occurrences of infant mortality correlated with the absence of specific α2δ isoforms (α2Δ-2 > α2δ-1 > α2δ-3), and was particularly observed in cages with behaviorally abnormal parenting animals of α2δ-2/-3 cross-breedings. Juvenile α2δ-1/-2 and α2δ-2/-3 double knockout mice displayed a waddling gate similar to ducky mice. However, in contrast to ducky and α2δ-1/-3 double knockout animals, α2δ-1/-2 and α2δ-2/-3 double knockout mice showed a more severe disease progression and highly impaired development. The observed phenotypes within the individual mouse lines may be linked to differences in the volume of specific brain regions. Reduced cortical volume in ducky mice, for example, was associated with a progressively decreased space between neurons, suggesting a reduction of total synaptic connections. Taken together, our findings show that α2δ subunits differentially regulate premature survival, postnatal growth, brain development, and behavior, suggesting specific neuronal functions in health and disease.
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Affiliation(s)
- Stefanie M. Geisler
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Ariane Benedetti
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Clemens L. Schöpf
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Nadia Stefanova
- Division of Neurobiology, Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
| | - Arnold Schwartz
- Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Gerald J. Obermair
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
- Division Physiology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
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22
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Pourhoseini S, Goswami-Sewell D, Zuniga-Sanchez E. Neurofascin Is a Novel Component of Rod Photoreceptor Synapses in the Outer Retina. Front Neural Circuits 2021; 15:635849. [PMID: 33643000 PMCID: PMC7902911 DOI: 10.3389/fncir.2021.635849] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/20/2021] [Indexed: 11/13/2022] Open
Abstract
Neural circuit formation is an intricate and complex process where multiple neuron types must come together to form synaptic connections at a precise location and time. How this process is orchestrated during development remains poorly understood. Cell adhesion molecules are known to play a pivotal role in assembling neural circuits. They serve as recognition molecules between corresponding synaptic partners. In this study, we identified a new player in assembling neural circuits in the outer retina, the L1-family cell adhesion molecule Neurofascin (Nfasc). Our data reveals Nfasc is expressed in the synaptic layer where photoreceptors make synaptic connections to their respective partners. A closer examination of Nfasc expression shows high levels of expression in rod bipolars but not in cone bipolars. Disruption of Nfasc using a conditional knockout allele results in selective loss of pre- and post-synaptic proteins in the rod synaptic layer but not in the cone synaptic layer. Electron microscopic analysis confirms that indeed there are abnormal synaptic structures with less dendrites of rod bipolars innervating rod terminals in loss of Nfasc animals. Consistent with these findings, we also observe a decrease in rod-driven retinal responses with disruption of Nfasc function but not in cone-driven responses. Taken together, our data suggest a new role of Nfasc in rod synapses within the mouse outer retina.
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Affiliation(s)
- Sahar Pourhoseini
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
| | | | - Elizabeth Zuniga-Sanchez
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
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23
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Lopachev AV, Lagarkova MA, Lebedeva OS, Ezhova MA, Kazanskaya RB, Timoshina YA, Khutorova AV, Akkuratov EE, Fedorova TN, Gainetdinov RR. Ouabain-Induced Gene Expression Changes in Human iPSC-Derived Neuron Culture Expressing Dopamine and cAMP-Regulated Phosphoprotein 32 and GABA Receptors. Brain Sci 2021; 11:brainsci11020203. [PMID: 33562186 PMCID: PMC7915459 DOI: 10.3390/brainsci11020203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/27/2021] [Accepted: 02/03/2021] [Indexed: 12/22/2022] Open
Abstract
Cardiotonic steroids (CTS) are specific inhibitors and endogenous ligands of a key enzyme in the CNS-the Na+, K+-ATPase, which maintains and creates an ion gradient on the plasma membrane of neurons. CTS cause the activation of various signaling cascades and changes in gene expression in neurons and other cell types. It is known that intracerebroventricular injection of cardiotonic steroid ouabain causes mania-like behavior in rodents, in part due to activation of dopamine-related signaling cascades in the dopamine and cAMP-regulated phosphoprotein 32 (DARPP-32) expressing medium spiny neurons in the striatum. Dopaminergic projections in the striatum innervate these GABAergic medium spiny neurons. The objective of this study was to assess changes in the expression of all genes in human iPSC-derived expressing DARPP-32 and GABA receptors neurons under the influence of ouabain. We noted a large number of statistically significant upregulated and downregulated genes after a 16-h incubation with non-toxic concentration (30 nM) of ouabain. These changes in the transcriptional activity were accomplished with activation of MAP-kinase ERK1/2 and transcriptional factor cAMP response element-binding protein (CREB). Thus, it can be concluded that 30 nM ouabain incubated for 16 h with human iPSC-derived expressing DARPP-32 and GABA receptors neurons activates genes associated with neuronal maturation and synapse formation, by increasing the expression of genes associated with translation, vesicular transport, and increased electron transport chain function. At the same time, the expression of genes associated with proliferation, migration, and early development of neurons decreases. These data indicate that non-toxic concentrations of ouabain may induce neuronal maturation, neurite growth, and increased synaptogenesis in dopamine-receptive GABAergic neurons, suggesting formation of plasticity and the establishment of new neuronal junctions.
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Affiliation(s)
- Alexander V. Lopachev
- Laboratory of Clinical and Experimental Neurochemistry, Research Center of Neurology, 125367 Moscow, Russia; (Y.A.T.); (A.V.K.); (T.N.F.)
- Correspondence:
| | - Maria A. Lagarkova
- Laboratory of Cell Biology, Federal Research and Clinical Center of Physical-Chemical Medicine Federal Medical Biological Agency, 119435 Moscow, Russia; (M.A.L.); (O.S.L.)
| | - Olga S. Lebedeva
- Laboratory of Cell Biology, Federal Research and Clinical Center of Physical-Chemical Medicine Federal Medical Biological Agency, 119435 Moscow, Russia; (M.A.L.); (O.S.L.)
| | - Margarita A. Ezhova
- Laboratory of Plant Genomics, Institute for Information Transmission Problems of the Russian Academy of Sciences, 127051 Moscow, Russia;
- Center of Life Sciences, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
| | - Rogneda B. Kazanskaya
- Biological Department, Saint Petersburg State University, 199034 St. Petersburg, Russia;
| | - Yulia A. Timoshina
- Laboratory of Clinical and Experimental Neurochemistry, Research Center of Neurology, 125367 Moscow, Russia; (Y.A.T.); (A.V.K.); (T.N.F.)
- Biological Department, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Anastasiya V. Khutorova
- Laboratory of Clinical and Experimental Neurochemistry, Research Center of Neurology, 125367 Moscow, Russia; (Y.A.T.); (A.V.K.); (T.N.F.)
- Biological Department, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Evgeny E. Akkuratov
- Department of Applied Physics, Royal Institute of Technology, Science for Life Laboratory, 171 65 Stockholm, Sweden;
| | - Tatiana N. Fedorova
- Laboratory of Clinical and Experimental Neurochemistry, Research Center of Neurology, 125367 Moscow, Russia; (Y.A.T.); (A.V.K.); (T.N.F.)
| | - Raul R. Gainetdinov
- Institute of Translational Biomedicine and Saint Petersburg University Hospital, Saint Petersburg State University, 199034 St. Petersburg, Russia;
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24
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Function of cone and cone-related pathways in Ca V1.4 IT mice. Sci Rep 2021; 11:2732. [PMID: 33526839 PMCID: PMC7851161 DOI: 10.1038/s41598-021-82210-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 01/11/2021] [Indexed: 11/09/2022] Open
Abstract
CaV1.4 L-type calcium channels are predominantly expressed in photoreceptor terminals playing a crucial role for synaptic transmission and, consequently, for vision. Human mutations in the encoding gene are associated with congenital stationary night blindness type-2. Besides rod-driven scotopic vision also cone-driven photopic responses are severely affected in patients. The present study therefore examined functional and morphological changes in cones and cone-related pathways in mice carrying the CaV1.4 gain-of function mutation I756T (CaV1.4-IT) using multielectrode array, patch-clamp and immunohistochemical analyses. CaV1.4-IT ganglion cell responses to photopic stimuli were seen only in a small fraction of cells indicative of a major impairment in the cone pathway. Though cone photoreceptors underwent morphological rearrangements, they retained their ability to release glutamate. Our functional data suggested a postsynaptic cone bipolar cell defect, supported by the fact that the majority of cone bipolar cells showed sprouting, while horizontal cells maintained contacts with cones and cone-to-horizontal cell input was preserved. Furthermore a reduction of basal Ca2+ influx by a calcium channel blocker was not sufficient to rescue synaptic transmission deficits caused by the CaV1.4-IT mutation. Long term treatments with low-dose Ca2+ channel blockers might however be beneficial reducing Ca2+ toxicity without major effects on ganglion cells responses.
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25
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Sun Y, Sun X. Exploring the interstitial system in the brain: the last mile of drug delivery. Rev Neurosci 2021; 32:363-377. [PMID: 33550781 DOI: 10.1515/revneuro-2020-0057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 12/08/2020] [Indexed: 11/15/2022]
Abstract
Brain interstitial system (ISS) is a nanoscale network of continuously connected tubes and sheets surrounding each neural cell in the central nervous system. ISS usually accounts for ∼20% of the brain volume, far more than the cerebral blood vessels, which account for 3%. The neuronal function, signaling pathways, and drug delivery are all closely related to the microenvironment provided by ISS. The objective of this paper is to give the readers a clear outline of detection, anatomy, function, and applications of ISS. This review describes the techniques propelling the exploration for ISS in chronological order, physiological function and pathological dysfunction of ISS, and strategies for drug delivery based on ISS. Biophysical features are the focus of ISS research, in which the diffusion characteristics have dominated. The various techniques that explore ISS take advantage of this feature. ISS provides an essential microenvironment for the health of cells and brain homeostasis, which plays an important functional role in brain health and disease. Direct intracranial administration allows the diffusion of drugs directly through ISS to successfully bypass the blood-brain barrier that prevents most drugs from reaching the brain. With the deepening of understanding of the brain ISS, the new research model that takes into account brain cells, cerebral vessels, and ISS will provide a new perspective and direction for understanding, utilizing, and protecting the brain.
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Affiliation(s)
- Yi Sun
- National Key Research Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, P. R. China.,Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University, Beijing 100191, P. R. China
| | - Xinping Sun
- Clinical Laboratory, Peking University International Hospital, Beijing 102206, P. R. China
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26
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Rai D, Akagi T, Shimohata A, Ishii T, Gangi M, Maruyama T, Wada-Kiyama Y, Ogiwara I, Kaneda M. Involvement of the C-terminal domain in cell surface localization and G-protein coupling of mGluR6. J Neurochem 2020; 158:837-848. [PMID: 33067823 DOI: 10.1111/jnc.15217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 05/25/2020] [Accepted: 10/11/2020] [Indexed: 01/05/2023]
Abstract
Metabotropic glutamate receptor 6, mGluR6, interacts with scaffold proteins and Gβγ subunits via its intracellular C-terminal domain (CTD). The mGluR6 pathway is critically involved in the retinal processing of visual signals. We herein investigated whether the CTD (residues 840-871) was necessary for mGluR6 cell surface localization and G-protein coupling using mGluR6-CTD mutants with immunocytochemistry, surface biotinylation assays, and electrophysiological approaches. We used 293T cells and primary hippocampal neurons as model systems. We examined C-terminally truncated mGluR6 and showed that the removal of up to residue 858 did not affect surface localization or glutamate-induced G-protein-mediated responses, whereas a 15-amino acid deletion (Δ857-871) impaired these functions. However, a 21-amino acid deletion (Δ851-871) restored surface localization and glutamate-dependent responses, which were again attenuated when the entire CTD was removed. The sequence alignment of group III mGluRs showed conserved amino acids resembling an ER retention motif in the CTD. These results suggest that the intracellular CTD is required for the cell surface transportation and receptor function of mGluR6, whereas it may contain regulatory elements for intracellular trafficking and signaling.
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Affiliation(s)
- Dilip Rai
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | - Takumi Akagi
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | | | - Toshiyuki Ishii
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | - Mie Gangi
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | - Takuma Maruyama
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | | | - Ikuo Ogiwara
- Department of Physiology, Nippon Medical School, Tokyo, Japan
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27
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Waldner DM, Ito K, Chen LL, Nguyen L, Chow RL, Lee A, Rancourt DE, Tremblay F, Stell WK, Bech-Hansen NT. Transgenic Expression of Cacna1f Rescues Vision and Retinal Morphology in a Mouse Model of Congenital Stationary Night Blindness 2A (CSNB2A). Transl Vis Sci Technol 2020; 9:19. [PMID: 33117610 PMCID: PMC7571326 DOI: 10.1167/tvst.9.11.19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 09/17/2020] [Indexed: 12/20/2022] Open
Abstract
Purpose Congenital stationary night blindness 2A (CSNB2A) is a genetic retinal disorder characterized by poor visual acuity, nystagmus, strabismus, and other signs of retinal dysfunction resulting from mutations in Cacna1f -the gene coding for the pore-forming subunit of the calcium channel CaV1.4. Mouse models of CSNB2A have shown that mutations causing the disease deleteriously affect photoreceptors and their synapses with second-order neurons. This study was undertaken to evaluate whether transgenic expression of Cacna1f could rescue morphology and visual function in a Cacna1f-KO model of CSNB2A. Methods Strategic creation, breeding and use of transgenic mouse lines allowed for Cre-driven retina-specific expression of Cacna1f in a CSNB2A model. Transgene expression and retinal morphology were investigated with immunohistochemistry in retinal wholemounts or cross-sections. Visual function was assessed by optokinetic response (OKR) analysis and electroretinography (ERG). Results Mosaic, prenatal expression of Cacna1f in the otherwise Cacna1f-KO retina was sufficient to rescue some visual function. Immunohistochemical analyses demonstrated wild-type-like photoreceptor and synaptic morphology in sections with transgenic expression of Cacna1f. Conclusions This report describes a novel system for Cre-inducible expression of Cacna1f in a Cacna1f-KO mouse model of CSNB2A and provides preclinical evidence for the potential use of gene therapy in the treatment of CSNB2A. Translational Relevance These data have relevance in the treatment of CSNB2A and in understanding how photoreceptor integration might be achieved in retinas in which photoreceptors have been lost, such as retinitis pigmentosa, age-related macular degeneration, and other degenerative conditions.
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Affiliation(s)
- Derek M Waldner
- Graduate Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Kenichi Ito
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
| | - Li-Li Chen
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Lisa Nguyen
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Robert L Chow
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, Department of Otolaryngology Head-Neck Surgery and Department of Neurology, University of Iowa, Iowa City, IA, USA
| | - Derrick E Rancourt
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
| | - Francois Tremblay
- Department of Ophthalmology and Visual Sciences, Faculty of Medicine, and Clinical Vision Sciences Program, Faculty of Health Dalhousie University, NS, Canada
| | - William K Stell
- Department of Cell Biology and Anatomy and Department of Surgery, Hotchkiss Brain Institute, and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - N Torben Bech-Hansen
- Department of Medical Genetics, and Department of Surgery, Alberta Children's Hospital Research Institute, and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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28
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Maddox JW, Randall KL, Yadav RP, Williams B, Hagen J, Derr PJ, Kerov V, Della Santina L, Baker SA, Artemyev N, Hoon M, Lee A. A dual role for Ca v1.4 Ca 2+ channels in the molecular and structural organization of the rod photoreceptor synapse. eLife 2020; 9:e62184. [PMID: 32940604 PMCID: PMC7561352 DOI: 10.7554/elife.62184] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 09/09/2020] [Indexed: 02/06/2023] Open
Abstract
Synapses are fundamental information processing units that rely on voltage-gated Ca2+ (Cav) channels to trigger Ca2+-dependent neurotransmitter release. Cav channels also play Ca2+-independent roles in other biological contexts, but whether they do so in axon terminals is unknown. Here, we addressed this unknown with respect to the requirement for Cav1.4 L-type channels for the formation of rod photoreceptor synapses in the retina. Using a mouse strain expressing a non-conducting mutant form of Cav1.4, we report that the Cav1.4 protein, but not its Ca2+ conductance, is required for the molecular assembly of rod synapses; however, Cav1.4 Ca2+ signals are needed for the appropriate recruitment of postsynaptic partners. Our results support a model in which presynaptic Cav channels serve both as organizers of synaptic building blocks and as sources of Ca2+ ions in building the first synapse of the visual pathway and perhaps more broadly in the nervous system.
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Affiliation(s)
- J Wesley Maddox
- Department of Molecular Physiology and Biophysics, University of IowaIowa CityUnited States
- Iowa Neuroscience Institute, University of IowaIowa CityUnited States
- Pappajohn Biomedical Institute, University of IowaIowa CityUnited States
| | - Kate L Randall
- Department of Molecular Physiology and Biophysics, University of IowaIowa CityUnited States
- Iowa Neuroscience Institute, University of IowaIowa CityUnited States
- Pappajohn Biomedical Institute, University of IowaIowa CityUnited States
| | - Ravi P Yadav
- Department of Molecular Physiology and Biophysics, University of IowaIowa CityUnited States
| | - Brittany Williams
- Department of Molecular Physiology and Biophysics, University of IowaIowa CityUnited States
- Iowa Neuroscience Institute, University of IowaIowa CityUnited States
- Pappajohn Biomedical Institute, University of IowaIowa CityUnited States
| | - Jussara Hagen
- Department of Molecular Physiology and Biophysics, University of IowaIowa CityUnited States
- Iowa Neuroscience Institute, University of IowaIowa CityUnited States
- Pappajohn Biomedical Institute, University of IowaIowa CityUnited States
| | - Paul J Derr
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
| | - Vasily Kerov
- Department of Molecular Physiology and Biophysics, University of IowaIowa CityUnited States
- Iowa Neuroscience Institute, University of IowaIowa CityUnited States
| | - Luca Della Santina
- Department of Ophthalmology, University of California, San FranciscoSan FranciscoUnited States
| | - Sheila A Baker
- Iowa Neuroscience Institute, University of IowaIowa CityUnited States
- Department of Biochemistry, University of IowaIowa CityUnited States
- Department of OphthalmologyIowa CityUnited States
| | - Nikolai Artemyev
- Department of Molecular Physiology and Biophysics, University of IowaIowa CityUnited States
- Iowa Neuroscience Institute, University of IowaIowa CityUnited States
- Department of OphthalmologyIowa CityUnited States
| | - Mrinalini Hoon
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
- Department of Ophthalmology and Visual Science, University of Wisconsin-MadisonMadisonUnited States
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of IowaIowa CityUnited States
- Iowa Neuroscience Institute, University of IowaIowa CityUnited States
- Pappajohn Biomedical Institute, University of IowaIowa CityUnited States
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29
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Interplay between cell-adhesion molecules governs synaptic wiring of cone photoreceptors. Proc Natl Acad Sci U S A 2020; 117:23914-23924. [PMID: 32879010 DOI: 10.1073/pnas.2009940117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Establishment of functional synaptic connections in a selective manner is essential for nervous system operation. In mammalian retinas, rod and cone photoreceptors form selective synaptic connections with different classes of bipolar cells (BCs) to propagate light signals. While there has been progress in elucidating rod wiring, molecular mechanisms used by cones to establish functional synapses with BCs have remained unknown. Using an unbiased proteomic strategy in cone-dominant species, we identified the cell-adhesion molecule ELFN2 to be pivotal for the functional wiring of cones with the ON type of BC. It is selectively expressed in cones and transsynaptically recruits the key neurotransmitter receptor mGluR6 in ON-BCs to enable synaptic transmission. Remarkably, ELFN2 in cone terminals functions in synergy with a related adhesion molecule, ELFN1, and their concerted interplay during development specifies selective wiring and transmission of cone signals. These findings identify a synaptic connectivity mechanism of cones and illustrate how interplay between adhesion molecules and postsynaptic transmitter receptors orchestrates functional synaptic specification in a neural circuit.
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30
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Ablinger C, Geisler SM, Stanika RI, Klein CT, Obermair GJ. Neuronal α 2δ proteins and brain disorders. Pflugers Arch 2020; 472:845-863. [PMID: 32607809 PMCID: PMC7351808 DOI: 10.1007/s00424-020-02420-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/08/2020] [Accepted: 06/12/2020] [Indexed: 01/31/2023]
Abstract
α2δ proteins are membrane-anchored extracellular glycoproteins which are abundantly expressed in the brain and the peripheral nervous system. They serve as regulatory subunits of voltage-gated calcium channels and, particularly in nerve cells, regulate presynaptic and postsynaptic functions independently from their role as channel subunits. α2δ proteins are the targets of the widely prescribed anti-epileptic and anti-allodynic drugs gabapentin and pregabalin, particularly for the treatment of neuropathic pain conditions. Recently, the human genes (CACNA2D1-4) encoding for the four known α2δ proteins (isoforms α2δ-1 to α2δ-4) have been linked to a large variety of neurological and neuropsychiatric disorders including epilepsy, autism spectrum disorders, bipolar disorders, schizophrenia, and depressive disorders. Here, we provide an overview of the hitherto identified disease associations of all known α2δ genes, hypothesize on the pathophysiological mechanisms considering their known physiological roles, and discuss the most immanent future research questions. Elucidating their specific physiological and pathophysiological mechanisms may open the way for developing entirely novel therapeutic paradigms for treating brain disorders.
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Affiliation(s)
- Cornelia Ablinger
- Institute of Physiology, Medical University Innsbruck, 6020, Innsbruck, Austria
| | - Stefanie M Geisler
- Department of Pharmacology and Toxicology, University of Innsbruck, 6020, Innsbruck, Austria
| | - Ruslan I Stanika
- Division Physiology, Karl Landsteiner University of Health Sciences, 3500, Krems, Austria
| | - Christian T Klein
- Department of Life Sciences, IMC University of Applied Sciences, 3500, Krems, Austria
| | - Gerald J Obermair
- Institute of Physiology, Medical University Innsbruck, 6020, Innsbruck, Austria.
- Division Physiology, Karl Landsteiner University of Health Sciences, 3500, Krems, Austria.
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31
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Peng YR, Sampath AP. LRR-ning the Rules: Synapse Organization in the Primary Rod Pathway. Neuron 2020; 105:949-951. [PMID: 32191854 DOI: 10.1016/j.neuron.2020.02.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In this issue of Neuron, Sinha et al. (2020) demonstrate that synaptic organization at rod bipolar cell terminals is regulated by a leucine-rich repeat protein, LRRTM4. LRRTM4 is expressed specifically by rod bipolar cells; eliminating it in mouse retina perturbs the organization of synaptic ribbons and impairs the function of inhibitory synapses.
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Affiliation(s)
- Yi-Rong Peng
- Department of Ophthalmology, Stein Eye Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095, USA.
| | - Alapakkam P Sampath
- Department of Ophthalmology, Stein Eye Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095, USA.
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32
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Held RG, Liu C, Ma K, Ramsey AM, Tarr TB, De Nola G, Wang SSH, Wang J, van den Maagdenberg AMJM, Schneider T, Sun J, Blanpied TA, Kaeser PS. Synapse and Active Zone Assembly in the Absence of Presynaptic Ca 2+ Channels and Ca 2+ Entry. Neuron 2020; 107:667-683.e9. [PMID: 32616470 DOI: 10.1016/j.neuron.2020.05.032] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 04/24/2020] [Accepted: 05/21/2020] [Indexed: 12/12/2022]
Abstract
Presynaptic CaV2 channels are essential for Ca2+-triggered exocytosis. In addition, there are two competing models for their roles in synapse structure. First, Ca2+ channels or Ca2+ entry may control synapse assembly. Second, active zone proteins may scaffold CaV2s to presynaptic release sites, and synapse structure is CaV2 independent. Here, we ablated all three CaV2s using conditional knockout in cultured hippocampal neurons or at the calyx of Held, which abolished evoked exocytosis. Compellingly, synapse and active zone structure, vesicle docking, and transsynaptic nano-organization were unimpaired. Similarly, long-term blockade of action potentials and Ca2+ entry did not disrupt active zone assembly. Although CaV2 knockout impaired the localization of β subunits, α2δ-1 localized normally. Rescue with CaV2 restored exocytosis, and CaV2 active zone targeting depended on the intracellular C-terminus. We conclude that synapse assembly is independent of CaV2s or Ca2+ entry through them. Instead, active zone proteins recruit and anchor CaV2s via CaV2 C-termini.
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Affiliation(s)
- Richard G Held
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Changliang Liu
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Kunpeng Ma
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing 100101, China
| | - Austin M Ramsey
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Tyler B Tarr
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Giovanni De Nola
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Shan Shan H Wang
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jiexin Wang
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Toni Schneider
- Institute for Neurophysiology, University of Cologne, Köln 50931, Germany
| | - Jianyuan Sun
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing 100101, China
| | - Thomas A Blanpied
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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33
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Furukawa T, Ueno A, Omori Y. Molecular mechanisms underlying selective synapse formation of vertebrate retinal photoreceptor cells. Cell Mol Life Sci 2020; 77:1251-1266. [PMID: 31586239 PMCID: PMC11105113 DOI: 10.1007/s00018-019-03324-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/21/2019] [Accepted: 09/25/2019] [Indexed: 11/29/2022]
Abstract
In vertebrate central nervous systems (CNSs), highly diverse neurons are selectively connected via synapses, which are essential for building an intricate neural network. The vertebrate retina is part of the CNS and is comprised of a distinct laminar organization, which serves as a good model system to study developmental synapse formation mechanisms. In the retina outer plexiform layer, rods and cones, two types of photoreceptor cells, elaborate selective synaptic contacts with ON- and/or OFF-bipolar cell terminals as well as with horizontal cell terminals. In the mouse retina, three photoreceptor subtypes and at least 15 bipolar subtypes exist. Previous and recent studies have significantly progressed our understanding of how selective synapse formation, between specific subtypes of photoreceptor and bipolar cells, is designed at the molecular level. In the ON pathway, photoreceptor-derived secreted and transmembrane proteins directly interact in trans with the GRM6 (mGluR6) complex, which is localized to ON-bipolar cell dendritic terminals, leading to selective synapse formation. Here, we review our current understanding of the key factors and mechanisms underlying selective synapse formation of photoreceptor cells with bipolar and horizontal cells in the retina. In addition, we describe how defects/mutations of the molecules involved in photoreceptor synapse formation are associated with human retinal diseases and visual disorders.
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Affiliation(s)
- Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Akiko Ueno
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoshihiro Omori
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
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34
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Dolphin AC, Lee A. Presynaptic calcium channels: specialized control of synaptic neurotransmitter release. Nat Rev Neurosci 2020; 21:213-229. [PMID: 32161339 PMCID: PMC7873717 DOI: 10.1038/s41583-020-0278-2] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2020] [Indexed: 11/09/2022]
Abstract
Chemical synapses are heterogeneous junctions formed between neurons that are specialized for the conversion of electrical impulses into the exocytotic release of neurotransmitters. Voltage-gated Ca2+ channels play a pivotal role in this process as they are the major conduits for the Ca2+ ions that trigger the fusion of neurotransmitter-containing vesicles with the presynaptic membrane. Alterations in the intrinsic function of these channels and their positioning within the active zone can profoundly alter the timing and strength of synaptic output. Advances in optical and electron microscopic imaging, structural biology and molecular techniques have facilitated recent breakthroughs in our understanding of the properties of voltage-gated Ca2+ channels that support their presynaptic functions. Here we examine the nature of these channels, how they are trafficked to and anchored within presynaptic boutons, and the mechanisms that allow them to function optimally in shaping the flow of information through neural circuits.
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA.
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Hagiwara A, Sugiyama N, Ohtsuka T. Impaired experience-dependent maternal care in presynaptic active zone protein CAST-deficient dams. Sci Rep 2020; 10:5238. [PMID: 32251313 PMCID: PMC7090055 DOI: 10.1038/s41598-020-62072-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 03/09/2020] [Indexed: 11/24/2022] Open
Abstract
Although sociological studies affirm the importance of parental care in the survival of offspring, maltreatment—including child neglect—remains prevalent in many countries. While child neglect is well known to affect child development, the causes of maternal neglect are poorly understood. Here, we found that female mice with a deletion mutation of CAST (a presynaptic release-machinery protein) showed significantly reduced weaning rate when primiparous and a recovered rate when multiparous. Indeed, when nurturing, primiparous and nulliparous CAST knock out (KO) mice exhibited less crouching time than control mice and moved greater distances. Contrary to expectations, plasma oxytocin (OXT) was not significantly reduced in CAST KO mice even though terminals of magnocellular neurons in the posterior pituitary expressed CAST. We further found that compared with control mice, CAST KO mice drank significantly less water when nurturing and had a greater preference for sucrose during pregnancy. We suggest that deficiency in presynaptic release-machinery protein impairs the facilitation of some maternal behaviours, which can be compensated for by experience and learning.
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Affiliation(s)
- Akari Hagiwara
- Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Naoko Sugiyama
- Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Toshihisa Ohtsuka
- Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.
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Ingram NT, Sampath AP, Fain GL. Membrane conductances of mouse cone photoreceptors. J Gen Physiol 2020; 152:e201912520. [PMID: 31986199 PMCID: PMC7054858 DOI: 10.1085/jgp.201912520] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/20/2019] [Accepted: 12/20/2019] [Indexed: 12/19/2022] Open
Abstract
Vertebrate photoreceptor cells respond to light through a closure of CNG channels located in the outer segment. Multiple voltage-sensitive channels in the photoreceptor inner segment serve to transform and transmit the light-induced outer-segment current response. Despite extensive studies in lower vertebrates, we do not know how these channels produce the photoresponse of mammalian photoreceptors. Here we examined these ionic conductances recorded from single mouse cones in unlabeled, dark-adapted retinal slices. First, we show measurements of the voltage dependence of the light response. After block of voltage-gated Ca2+ channels, the light-dependent current was nearly linear within the physiological range of voltages with constant chord conductance and a reversal potential similar to that previously determined in lower vertebrate photoreceptors. At a dark resting membrane potential of -45 mV, cones maintain a standing Ca2+ current (iCa) between 15 and 20 pA. We characterized the time and voltage dependence of iCa and a calcium-activated anion channel. After constitutive closure of the CNG channels by the nonhydrolysable analogue GTP-γ-S, we observed a light-dependent increase in iCa followed by a Ca2+-activated K+ current, both probably the result of feedback from horizontal cells. We also recorded the hyperpolarization-activated cyclic nucleotide-gated (HCN) conductance (ih) and measured its current-voltage relationship and reversal potential. With small hyperpolarizations, ih activated with a time constant of 25 ms; activation was speeded with larger hyperpolarizations. Finally, we characterized two voltage-gated K+-conductances (iK). Depolarizing steps beginning at -10 mV activated a transient, outwardly rectifying iK blocked by 4-AP and insensitive to TEA. A sustained iK isolated through subtraction was blocked by TEA but was insensitive to 4-AP. The sustained iK had a nearly linear voltage dependence throughout the physiological voltage range of the cone. Together these data constitute the first comprehensive study of the channel conductances of mouse photoreceptors.
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Affiliation(s)
- Norianne T. Ingram
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, CA
| | - Alapakkam P. Sampath
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, CA
| | - Gordon L. Fain
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, CA
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Schlegel DK, Glasauer SMK, Mateos JM, Barmettler G, Ziegler U, Neuhauss SCF. A New Zebrafish Model for CACNA2D4-Dysfunction. Invest Ophthalmol Vis Sci 2020; 60:5124-5135. [PMID: 31834350 DOI: 10.1167/iovs.19-26759] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Mutations in CACNA2D4, encoding the α2δ4 subunit of retinal voltage-gated calcium channels (Cav), cause a rare type of retinal dysfunction in human, mainly affecting cone vision. Here, we investigate the role of CACNA2D4 in targeting of Cav, its influence on cone-mediated signal transmission, and the cellular and subcellular changes upon loss of α2δ4 by exploiting the advantages of the cone-dominant zebrafish as model system. Methods We identified two zebrafish CACNA2D4 paralogs (cacna2d4a and cacna2d4b), analyzed their expression by RNA in situ hybridization and introduced truncating frameshift mutations through CRISPR/Cas9-mediated mutagenesis. We analyzed retinal function and morphology of the single and double mutant lines by electroretinography, immunohistochemistry, light- and electron microscopy. Results Knockout of cacna2d4b reduces the expression of Cacna1fa, the pore-forming subunit of retinal Cav1.4, whereas loss of cacna2d4a did not. Only knockout of both paralogs impaired cone-mediated ERG b-wave amplitude. The number of "floating" ribbons is increased in double-KO, while retinal morphology and expression of postsynaptic mGluR6b remain largely unaffected. Both Cacna1fa and Ribeyeb show ectopic punctate expression in cacna2d4b-KO and double-KO photoreceptors. Conclusions We find that increasing the expression of Cav at the synaptic membrane is an evolutionarily conserved function of Cacna2d4b. Yet, since both paralogs participate in cone synaptic transmission, we propose partial subfunctionalization in zebrafish. Similar to human patients, our double KO zebrafish model shows mild cone dysfunction, which was not associated with signs of retinal degeneration. Therefore, cacna2d4-KO zebrafish is a suitable model to study the pathophysiological mechanisms underlying CACNA2D4 dysfunction in human.
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Affiliation(s)
- Domino K Schlegel
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland.,Life Science Zurich Graduate School, Ph.D. Program in Molecular Life Sciences, Zurich, Switzerland
| | - Stella M K Glasauer
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland.,Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, California, United States.,Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, United States
| | - José M Mateos
- Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland
| | - Gery Barmettler
- Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland
| | - Urs Ziegler
- Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland
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Albrecht NE, Alevy J, Jiang D, Burger CA, Liu BI, Li F, Wang J, Kim SY, Hsu CW, Kalaga S, Udensi U, Asomugha C, Bohat R, Gaspero A, Justice MJ, Westenskow PD, Yamamoto S, Seavitt JR, Beaudet AL, Dickinson ME, Samuel MA. Rapid and Integrative Discovery of Retina Regulatory Molecules. Cell Rep 2020; 24:2506-2519. [PMID: 30157441 DOI: 10.1016/j.celrep.2018.07.090] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 05/15/2018] [Accepted: 07/27/2018] [Indexed: 12/26/2022] Open
Abstract
Retinal function relies on precisely organized neurons and synapses and a properly patterned vasculature to support them. Alterations in these features can result in vision loss. However, our understanding of retinal organization pathways remains incomplete because of a lack of methods to rapidly identify neuron and vasculature regulators in mammals. Here we developed a pipeline for the identification of neural and synaptic integrity genes by high-throughput retinal screening (INSiGHT) that analyzes candidate expression, vascular patterning, cellular organization, and synaptic arrangement. Using this system, we examined 102 mutant mouse lines and identified 16 unique retinal regulatory genes. Fifteen of these candidates are identified as novel retina regulators, and many (9 of 16) are associated with human neural diseases. These results expand the genetic landscape involved in retinal circuit organization and provide a road map for continued discovery of mammalian retinal regulators and disease-causing alleles.
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Affiliation(s)
- Nicholas E Albrecht
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jonathan Alevy
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Danye Jiang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Courtney A Burger
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Brian I Liu
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Fenge Li
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Julia Wang
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Seon-Young Kim
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Chih-Wei Hsu
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sowmya Kalaga
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Uchechukwu Udensi
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Chinwe Asomugha
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ritu Bohat
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Angelina Gaspero
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Monica J Justice
- Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Peter D Westenskow
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Shinya Yamamoto
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - John R Seavitt
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Arthur L Beaudet
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mary E Dickinson
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Melanie A Samuel
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA.
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LRRTM4: A Novel Regulator of Presynaptic Inhibition and Ribbon Synapse Arrangements of Retinal Bipolar Cells. Neuron 2020; 105:1007-1017.e5. [PMID: 31974009 DOI: 10.1016/j.neuron.2019.12.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 10/17/2019] [Accepted: 12/23/2019] [Indexed: 12/16/2022]
Abstract
LRRTM4 is a transsynaptic adhesion protein regulating glutamatergic synapse assembly on dendrites of central neurons. In the mouse retina, we find that LRRTM4 is enriched at GABAergic synapses on axon terminals of rod bipolar cells (RBCs). Knockout of LRRTM4 reduces RBC axonal GABAA and GABAC receptor clustering and disrupts presynaptic inhibition onto RBC terminals. LRRTM4 removal also perturbs the stereotyped output synapse arrangement at RBC terminals. Synaptic ribbons are normally apposed to two distinct postsynaptic "dyad" partners, but in the absence of LRRTM4, "monad" and "triad" arrangements are also formed. RBCs from retinas deficient in GABA release also demonstrate dyad mis-arrangements but maintain LRRTM4 expression, suggesting that defects in dyad organization in the LRRTM4 knockout could originate from reduced GABA receptor function. LRRTM4 is thus a key synapse organizing molecule at RBC terminals, where it regulates function of GABAergic synapses and assembly of RBC synaptic dyads.
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40
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Orlandi C, Omori Y, Wang Y, Cao Y, Ueno A, Roux MJ, Condomitti G, de Wit J, Kanagawa M, Furukawa T, Martemyanov KA. Transsynaptic Binding of Orphan Receptor GPR179 to Dystroglycan-Pikachurin Complex Is Essential for the Synaptic Organization of Photoreceptors. Cell Rep 2020; 25:130-145.e5. [PMID: 30282023 PMCID: PMC6203450 DOI: 10.1016/j.celrep.2018.08.068] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 08/16/2018] [Accepted: 08/23/2018] [Indexed: 01/05/2023] Open
Abstract
Establishing synaptic contacts between neurons is paramount for nervous system function. This process involves transsynaptic interactions between a host of cell adhesion molecules that act in cooperation with the proteins of the extracellular matrix to specify uniquephysiological propertiesofindividual synaptic connections. However, understanding of the molecular mechanisms that generate functional diversity in an input-specific fashion is limited. In this study, we identify that major components of the extracellular matrix proteins present in the synaptic cleft—members oftheheparansulfateproteoglycan (HSPG) family—associate with the GPR158/179 group of orphan receptors. Using the mammalian retina as a model system, we demonstrate that the HSPG member Pikachurin, released by photoreceptors, recruits a key post-synaptic signaling complex of downstream ON-bipolar neurons in coordination with the presynaptic dystroglycan glycoprotein complex. We further demonstrate that this transsynaptic assembly plays an essential role in synaptic transmission of photoreceptor signals. Orlandi et al. identify transsynaptic assembly at photoreceptor synapses involving pre-synaptic dystrophindystroglycan complex and the postsynaptic orphan receptor GPR179 bridged by HSPG protein Pikachurin in the cleft and demonstrate its role in shaping transmission of photoreceptor signals.
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Affiliation(s)
- Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yoshihiro Omori
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Yuchen Wang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Akiko Ueno
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Michel J Roux
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Centre National de la Recherche Scientifique, UMR7104, INSERM, U1258, Illkirch, France
| | - Giuseppe Condomitti
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Herestraat 49, 3000 Leuven, Belgium
| | - Joris de Wit
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Herestraat 49, 3000 Leuven, Belgium
| | - Motoi Kanagawa
- Division of Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
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41
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Hoover KM, Gratz SJ, Qi N, Herrmann KA, Liu Y, Perry-Richardson JJ, Vanderzalm PJ, O'Connor-Giles KM, Broihier HT. The calcium channel subunit α 2δ-3 organizes synapses via an activity-dependent and autocrine BMP signaling pathway. Nat Commun 2019; 10:5575. [PMID: 31811118 PMCID: PMC6898181 DOI: 10.1038/s41467-019-13165-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 10/23/2019] [Indexed: 12/17/2022] Open
Abstract
Synapses are highly specialized for neurotransmitter signaling, yet activity-dependent growth factor release also plays critical roles at synapses. While efficient neurotransmitter signaling relies on precise apposition of release sites and neurotransmitter receptors, molecular mechanisms enabling high-fidelity growth factor signaling within the synaptic microenvironment remain obscure. Here we show that the auxiliary calcium channel subunit α2δ-3 promotes the function of an activity-dependent autocrine Bone Morphogenetic Protein (BMP) signaling pathway at the Drosophila neuromuscular junction (NMJ). α2δ proteins have conserved synaptogenic activity, although how they execute this function has remained elusive. We find that α2δ-3 provides an extracellular scaffold for an autocrine BMP signal, suggesting a mechanistic framework for understanding α2δ's conserved role in synapse organization. We further establish a transcriptional requirement for activity-dependent, autocrine BMP signaling in determining synapse density, structure, and function. We propose that activity-dependent, autocrine signals provide neurons with continuous feedback on their activity state for modulating both synapse structure and function.
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Affiliation(s)
- Kendall M Hoover
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Scott J Gratz
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
| | - Nova Qi
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Kelsey A Herrmann
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Yizhou Liu
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Jahci J Perry-Richardson
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Pamela J Vanderzalm
- Department of Biology, John Carroll University, University Heights, OH, 44118, USA
| | | | - Heather T Broihier
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
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Xu L, Bolch SN, Santiago CP, Dyka FM, Akil O, Lobanova ES, Wang Y, Martemyanov KA, Hauswirth WW, Smith WC, Handa JT, Blackshaw S, Ash JD, Dinculescu A. Clarin-1 expression in adult mouse and human retina highlights a role of Müller glia in Usher syndrome. J Pathol 2019; 250:195-204. [PMID: 31625146 PMCID: PMC7003947 DOI: 10.1002/path.5360] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/17/2019] [Accepted: 10/16/2019] [Indexed: 02/06/2023]
Abstract
Usher syndrome type 3 (USH3) is an autosomal recessively inherited disorder caused by mutations in the gene clarin‐1 (CLRN1), leading to combined progressive hearing loss and retinal degeneration. The cellular distribution of CLRN1 in the retina remains uncertain, either because its expression levels are low or because its epitopes are masked. Indeed, in the adult mouse retina, Clrn1 mRNA is developmentally downregulated, detectable only by RT‐PCR. In this study we used the highly sensitive RNAscope in situ hybridization assay and single‐cell RNA‐sequencing techniques to investigate the distribution of Clrn1 and CLRN1 in mouse and human retina, respectively. We found that Clrn1 transcripts in mouse tissue are localized to the inner retina during postnatal development and in adult stages. The pattern of Clrn1 mRNA cellular expression is similar in both mouse and human adult retina, with CLRN1 transcripts being localized in Müller glia, and not photoreceptors. We generated a novel knock‐in mouse with a hemagglutinin (HA) epitope‐tagged CLRN1 and showed that CLRN1 is expressed continuously at the protein level in the retina. Following enzymatic deglycosylation and immunoblotting analysis, we detected a single CLRN1‐specific protein band in homogenates of mouse and human retina, consistent in size with the main CLRN1 isoform. Taken together, our results implicate Müller glia in USH3 pathology, placing this cell type to the center of future mechanistic and therapeutic studies to prevent vision loss in this disease. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Lei Xu
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA
| | - Susan N Bolch
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA
| | - Clayton P Santiago
- Solomon H Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Frank M Dyka
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA
| | - Omar Akil
- Department of Otolaryngology-HNS, University of California, San Francisco, CA, USA
| | | | - Yuchen Wang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | | | | | - W Clay Smith
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA
| | - James T Handa
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Seth Blackshaw
- Solomon H Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.,Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Center for Human Systems Biology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - John D Ash
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA
| | - Astra Dinculescu
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA
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Cingolani LA, Vitale C, Dityatev A. Intra- and Extracellular Pillars of a Unifying Framework for Homeostatic Plasticity: A Crosstalk Between Metabotropic Receptors and Extracellular Matrix. Front Cell Neurosci 2019; 13:513. [PMID: 31803023 PMCID: PMC6877475 DOI: 10.3389/fncel.2019.00513] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 10/29/2019] [Indexed: 11/18/2022] Open
Abstract
In the face of chronic changes in incoming sensory inputs, neuronal networks are capable of maintaining stable conditions of electrical activity over prolonged periods of time by adjusting synaptic strength, to amplify or dampen incoming inputs [homeostatic synaptic plasticity (HSP)], or by altering the intrinsic excitability of individual neurons [homeostatic intrinsic plasticity (HIP)]. Emerging evidence suggests a synergistic interplay between extracellular matrix (ECM) and metabotropic receptors in both forms of homeostatic plasticity. Activation of dopaminergic, serotonergic, or glutamate metabotropic receptors stimulates intracellular signaling through calmodulin-dependent protein kinase II, protein kinase A, protein kinase C, and inositol trisphosphate receptors, and induces changes in expression of ECM molecules and proteolysis of both ECM molecules (lecticans) and ECM receptors (NPR, CD44). The resulting remodeling of perisynaptic and synaptic ECM provides permissive conditions for HSP and plays an instructive role by recruiting additional signaling cascades, such as those through metabotropic glutamate receptors and integrins. The superimposition of all these signaling events determines intracellular and diffusional trafficking of ionotropic glutamate receptors, resulting in HSP and modulation of conditions for inducing Hebbian synaptic plasticity (i.e., metaplasticity). It also controls cell-surface delivery and activity of voltage- and Ca2+-gated ion channels, resulting in HIP. These mechanisms may modify epileptogenesis and become a target for therapeutic interventions.
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Affiliation(s)
- Lorenzo A. Cingolani
- Department of Life Sciences, University of Trieste, Trieste, Italy
- Center for Synaptic Neuroscience and Technology (NSYN), Istituto Italiano di Tecnologia, Genoa, Italy
| | - Carmela Vitale
- Center for Synaptic Neuroscience and Technology (NSYN), Istituto Italiano di Tecnologia, Genoa, Italy
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Alexander Dityatev
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
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Van Hook MJ, Nawy S, Thoreson WB. Voltage- and calcium-gated ion channels of neurons in the vertebrate retina. Prog Retin Eye Res 2019; 72:100760. [PMID: 31078724 PMCID: PMC6739185 DOI: 10.1016/j.preteyeres.2019.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/25/2019] [Accepted: 05/01/2019] [Indexed: 02/06/2023]
Abstract
In this review, we summarize studies investigating the types and distribution of voltage- and calcium-gated ion channels in the different classes of retinal neurons: rods, cones, horizontal cells, bipolar cells, amacrine cells, interplexiform cells, and ganglion cells. We discuss differences among cell subtypes within these major cell classes, as well as differences among species, and consider how different ion channels shape the responses of different neurons. For example, even though second-order bipolar and horizontal cells do not typically generate fast sodium-dependent action potentials, many of these cells nevertheless possess fast sodium currents that can enhance their kinetic response capabilities. Ca2+ channel activity can also shape response kinetics as well as regulating synaptic release. The L-type Ca2+ channel subtype, CaV1.4, expressed in photoreceptor cells exhibits specific properties matching the particular needs of these cells such as limited inactivation which allows sustained channel activity and maintained synaptic release in darkness. The particular properties of K+ and Cl- channels in different retinal neurons shape resting membrane potentials, response kinetics and spiking behavior. A remaining challenge is to characterize the specific distributions of ion channels in the more than 100 individual cell types that have been identified in the retina and to describe how these particular ion channels sculpt neuronal responses to assist in the processing of visual information by the retina.
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Affiliation(s)
- Matthew J Van Hook
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA
| | - Scott Nawy
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA
| | - Wallace B Thoreson
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA.
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Activation of Rod Input in a Model of Retinal Degeneration Reverses Retinal Remodeling and Induces Formation of Functional Synapses and Recovery of Visual Signaling in the Adult Retina. J Neurosci 2019; 39:6798-6810. [PMID: 31285302 DOI: 10.1523/jneurosci.2902-18.2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 05/28/2019] [Accepted: 06/18/2019] [Indexed: 12/31/2022] Open
Abstract
A major cause of human blindness is the death of rod photoreceptors. As rods degenerate, synaptic structures between rod and rod bipolar cells disappear and the rod bipolar cells extend their dendrites and occasionally make aberrant contacts. Such changes are broadly observed in blinding disorders caused by photoreceptor cell death and are thought to occur in response to deafferentation. How the remodeled retinal circuit affects visual processing following rod rescue is not known. To address this question, we generated male and female transgenic mice wherein a disrupted cGMP-gated channel (CNG) gene can be repaired at the endogenous locus and at different stages of degeneration by tamoxifen-inducible cre-mediated recombination. In normal rods, light-induced closure of CNG channels leads to hyperpolarization of the cell, reducing neurotransmitter release at the synapse. Similarly, rods lacking CNG channels exhibit a resting membrane potential that was ~10 mV hyperpolarized compared to WT rods, indicating diminished glutamate release. Retinas from these mice undergo stereotypic retinal remodeling as a consequence of rod malfunction and degeneration. Upon tamoxifen-induced expression of CNG channels, rods recovered their structure and exhibited normal light responses. Moreover, we show that the adult mouse retina displays a surprising degree of plasticity upon activation of rod input. Wayward bipolar cell dendrites establish contact with rods to support normal synaptic transmission, which is propagated to the retinal ganglion cells. These findings demonstrate remarkable plasticity extending beyond the developmental period and support efforts to repair or replace defective rods in patients blinded by rod degeneration.SIGNIFICANCE STATEMENT Current strategies for treatment of neurodegenerative disorders are focused on the repair of the primary affected cell type. However, the defective neurons function within a complex neural circuitry, which also becomes degraded during disease. It is not known whether rescued neurons and the remodeled circuit will establish communication to regain normal function. We show that the adult mammalian neural retina exhibits a surprising degree of plasticity following rescue of rod photoreceptors. The wayward dendrites of rod bipolar cells re-establish contact with rods to support normal synaptic transmission, which is propagated to the retinal ganglion cells. These findings support efforts to repair or replace defective rods in patients blinded by rod cell loss.
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Laird JG, Gardner SH, Kopel AJ, Kerov V, Lee A, Baker SA. Rescue of Rod Synapses by Induction of Cav Alpha 1F in the Mature Cav1.4 Knock-Out Mouse Retina. Invest Ophthalmol Vis Sci 2019; 60:3150-3161. [PMID: 31335952 PMCID: PMC6656410 DOI: 10.1167/iovs.19-27226] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 06/24/2019] [Indexed: 01/10/2023] Open
Abstract
Purpose Cav1.4 is a voltage-gated calcium channel clustered at the presynaptic active zones of photoreceptors. Cav1.4 functions in communication by mediating the Ca2+ influx that triggers neurotransmitter release. It also aids in development since rod ribbon synapses do not form in Cav1.4 knock-out mice. Here we used a rescue strategy to investigate the ability of Cav1.4 to trigger synaptogenesis in both immature and mature mouse rods. Methods In vivo electroporation was used to transiently express Cav α1F or tamoxifen-inducible Cav α1F in a subset of Cav1.4 knock-out mouse rods. Synaptogenesis was assayed using morphologic markers and a vision-guided water maze. Results We found that introduction of Cav α1F to knock-out terminals rescued synaptic development as indicated by PSD-95 expression and elongated ribbons. When expression of Cav α1F was induced in mature animals, we again found restoration of PSD-95 and elongated ribbons. However, the induced expression of Cav α1F led to diffuse distribution of Cav α1F in the terminal instead of being clustered beneath the ribbon. Approximately a quarter of treated animals passed the water maze test, suggesting the rescue of retinal signaling in these mice. Conclusions These data confirm that Cav α1F expression is necessary for rod synaptic terminal development and demonstrate that rescue is robust even in adult animals with late stages of synaptic disease. The degree of rod synaptic plasticity seen here should be sufficient to support future vision-restoring treatments such as gene or cell replacement that will require photoreceptor synaptic rewiring.
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Affiliation(s)
- Joseph G. Laird
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Sarah H. Gardner
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Ariel J. Kopel
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Vasily Kerov
- Molecular Physiology and Biophysics, University of Iowa, Iowa City, United States
| | - Amy Lee
- Molecular Physiology and Biophysics, University of Iowa, Iowa City, United States
- Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, United States
- Department of Neurology, University of Iowa, Iowa City, United States
- Iowa Neuroscience Institute, University of Iowa, Iowa City, United States
| | - Sheila A. Baker
- Department of Biochemistry, University of Iowa, Iowa City, United States
- Iowa Neuroscience Institute, University of Iowa, Iowa City, United States
- Ophthalmology and Visual Sciences and the Institute for Vision Research, University of Iowa, Iowa City, United States
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Hasan N, Pangeni G, Cobb CA, Ray TA, Nettesheim ER, Ertel KJ, Lipinski DM, McCall MA, Gregg RG. Presynaptic Expression of LRIT3 Transsynaptically Organizes the Postsynaptic Glutamate Signaling Complex Containing TRPM1. Cell Rep 2019; 27:3107-3116.e3. [PMID: 31189098 PMCID: PMC6628893 DOI: 10.1016/j.celrep.2019.05.056] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 03/15/2019] [Accepted: 05/15/2019] [Indexed: 11/29/2022] Open
Abstract
Throughout the CNS, interactions between pre- and postsynaptic adhesion molecules establish normal synaptic structure and function. Leucine-rich repeat (LRR) domain-containing proteins are a large family that has a diversity of ligands, and their absence can cause disease. At the first retinal synapse, the absence of LRIT3 expression leads to the disassembly of the postsynaptic glutamate signaling complex (signalplex) expressed on depolarizing bipolar cell (DBC) dendrites. The prevalent view is that assembly of the signalplex results from direct postsynaptic protein:protein interactions. In contrast, we demonstrate that LRIT3 is expressed presynaptically, in rod photoreceptors (rods), and when we restore LRIT3 expression in Lrit3-/- rods, we restore expression of the postsynaptic glutamate signalplex and rod-driven vision. Our results demonstrate that, in the retina, the LRR-containing protein LRIT3 acts as a transsynaptic organizer of the postsynaptic complex required for normal synaptic function.
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Affiliation(s)
- Nazarul Hasan
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292, USA
| | - Gobinda Pangeni
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40292, USA
| | - Catherine A Cobb
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292, USA
| | - Thomas A Ray
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292, USA
| | - Emily R Nettesheim
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Kristina J Ertel
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Daniel M Lipinski
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford OX3 9DU, UK
| | - Maureen A McCall
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40292, USA; Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292, USA
| | - Ronald G Gregg
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292, USA; Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40292, USA; Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292, USA.
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Grassmeyer JJ, Cahill AL, Hays CL, Barta C, Quadros RM, Gurumurthy CB, Thoreson WB. Ca 2+ sensor synaptotagmin-1 mediates exocytosis in mammalian photoreceptors. eLife 2019; 8:e45946. [PMID: 31172949 PMCID: PMC6588344 DOI: 10.7554/elife.45946] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 06/06/2019] [Indexed: 11/24/2022] Open
Abstract
To encode light-dependent changes in membrane potential, rod and cone photoreceptors utilize synaptic ribbons to sustain continuous exocytosis while making rapid, fine adjustments to release rate. Release kinetics are shaped by vesicle delivery down ribbons and by properties of exocytotic Ca2+ sensors. We tested the role for synaptotagmin-1 (Syt1) in photoreceptor exocytosis by using novel mouse lines in which Syt1 was conditionally removed from rods or cones. Photoreceptors lacking Syt1 exhibited marked reductions in exocytosis as measured by electroretinography and single-cell recordings. Syt1 mediated all evoked release in cones, whereas rods appeared capable of some slow Syt1-independent release. Spontaneous release frequency was unchanged in cones but increased in rods lacking Syt1. Loss of Syt1 did not alter synaptic anatomy or reduce Ca2+ currents. These results suggest that Syt1 mediates both phasic and tonic release at photoreceptor synapses, revealing unexpected flexibility in the ability of Syt1 to regulate Ca2+-dependent synaptic transmission.
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Affiliation(s)
- Justin J Grassmeyer
- Truhlsen Eye Institute, Department of Ophthalmology and Visual SciencesUniversity of Nebraska Medical CenterOmahaUnited States
- Department of Pharmacology and Experimental NeuroscienceUniversity of Nebraska Medical CenterOmahaUnited States
| | - Asia L Cahill
- Truhlsen Eye Institute, Department of Ophthalmology and Visual SciencesUniversity of Nebraska Medical CenterOmahaUnited States
| | - Cassandra L Hays
- Truhlsen Eye Institute, Department of Ophthalmology and Visual SciencesUniversity of Nebraska Medical CenterOmahaUnited States
- Department of Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaUnited States
| | - Cody Barta
- Truhlsen Eye Institute, Department of Ophthalmology and Visual SciencesUniversity of Nebraska Medical CenterOmahaUnited States
| | - Rolen M Quadros
- Mouse Genome Engineering Core Facility, Vice Chancellor for Research OfficeUniversity of Nebraska Medical CenterOmahaUnited States
| | - Channabasavaiah B Gurumurthy
- Mouse Genome Engineering Core Facility, Vice Chancellor for Research OfficeUniversity of Nebraska Medical CenterOmahaUnited States
- Developmental Neuroscience, Munroe Meyer Institute for Genetics and RehabilitationUniversity of Nebraska Medical CenterOmahaUnited States
| | - Wallace B Thoreson
- Truhlsen Eye Institute, Department of Ophthalmology and Visual SciencesUniversity of Nebraska Medical CenterOmahaUnited States
- Department of Pharmacology and Experimental NeuroscienceUniversity of Nebraska Medical CenterOmahaUnited States
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Haworth AS, Brackenbury WJ. Emerging roles for multifunctional ion channel auxiliary subunits in cancer. Cell Calcium 2019; 80:125-140. [PMID: 31071485 PMCID: PMC6553682 DOI: 10.1016/j.ceca.2019.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 04/16/2019] [Accepted: 04/16/2019] [Indexed: 02/07/2023]
Abstract
Several superfamilies of plasma membrane channels which regulate transmembrane ion flux have also been shown to regulate a multitude of cellular processes, including proliferation and migration. Ion channels are typically multimeric complexes consisting of conducting subunits and auxiliary, non-conducting subunits. Auxiliary subunits modulate the function of conducting subunits and have putative non-conducting roles, further expanding the repertoire of cellular processes governed by ion channel complexes to processes such as transcellular adhesion and gene transcription. Given this expansive influence of ion channels on cellular behaviour it is perhaps no surprise that aberrant ion channel expression is a common occurrence in cancer. This review will focus on the conducting and non-conducting roles of the auxiliary subunits of various Ca2+, K+, Na+ and Cl- channels and the burgeoning evidence linking such auxiliary subunits to cancer. Several subunits are upregulated (e.g. Cavβ, Cavγ) and downregulated (e.g. Kvβ) in cancer, while other subunits have been functionally implicated as oncogenes (e.g. Navβ1, Cavα2δ1) and tumour suppressor genes (e.g. CLCA2, KCNE2, BKγ1) based on in vivo studies. The strengthening link between ion channel auxiliary subunits and cancer has exposed these subunits as potential biomarkers and therapeutic targets. However further mechanistic understanding is required into how these subunits contribute to tumour progression before their therapeutic potential can be fully realised.
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Affiliation(s)
- Alexander S Haworth
- Department of Biology, University of York, Heslington, York, YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington, York, YO10 5DD, UK
| | - William J Brackenbury
- Department of Biology, University of York, Heslington, York, YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington, York, YO10 5DD, UK.
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Tan YZ, Fei DD, He XN, Dai JM, Xu RC, Xu XY, Wu JJ, Li B. L-type voltage-gated calcium channels in stem cells and tissue engineering. Cell Prolif 2019; 52:e12623. [PMID: 31115100 PMCID: PMC6669004 DOI: 10.1111/cpr.12623] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/26/2019] [Accepted: 03/29/2019] [Indexed: 12/22/2022] Open
Abstract
L‐type voltage‐gated calcium ion channels (L‐VGCCs) have been demonstrated to be the mediator of several significant intracellular activities in excitable cells, such as neurons, chromaffin cells and myocytes. Recently, an increasing number of studies have investigated the function of L‐VGCCs in non‐excitable cells, particularly stem cells. However, there appear to be no systematic reviews of the relationship between L‐VGCCs and stem cells, and filling this gap is prescient considering the contribution of L‐VGCCs to the proliferation and differentiation of several types of stem cells. This review will discuss the possible involvement of L‐VGCCs in stem cells, mainly focusing on osteogenesis mediated by mesenchymal stem cells (MSCs) from different tissues and neurogenesis mediated by neural stem/progenitor cells (NSCs). Additionally, advanced applications that use these channels as the target for tissue engineering, which may offer the hope of tissue regeneration in the future, will also be explored.
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Affiliation(s)
- Yi-Zhou Tan
- Department of Periodontology, State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Engineering Research Center for Dental Materials and Advanced Manufacture, School of Stomatology, The Fourth Military Medical University, Xi'an, China
| | - Dong-Dong Fei
- Department of Periodontology, State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Engineering Research Center for Dental Materials and Advanced Manufacture, School of Stomatology, The Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases, Center for Tissue Engineering, Fourth Military Medical University, Xi'an, China
| | - Xiao-Ning He
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases, Center for Tissue Engineering, Fourth Military Medical University, Xi'an, China
| | - Ji-Min Dai
- Doctoral students of eight-year program, The Fourth Military Medical University, Xi'an, China
| | - Rong-Chen Xu
- Doctoral students of eight-year program, The Fourth Military Medical University, Xi'an, China
| | - Xin-Yue Xu
- Department of Periodontology, State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Engineering Research Center for Dental Materials and Advanced Manufacture, School of Stomatology, The Fourth Military Medical University, Xi'an, China
| | - Jun-Jie Wu
- Department of Orthodontics, State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Clinical Research Center for Oral Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an, China
| | - Bei Li
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases, Center for Tissue Engineering, Fourth Military Medical University, Xi'an, China
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