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Hasan N, Gregg RG. Cone Synaptic function is modulated by the leucine rich repeat (LRR) adhesion molecule LRFN2. eNeuro 2024; 11:ENEURO.0120-23.2024. [PMID: 38408870 PMCID: PMC10957230 DOI: 10.1523/eneuro.0120-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 02/11/2024] [Accepted: 02/18/2024] [Indexed: 02/28/2024] Open
Abstract
Daylight vision is mediated by cone photoreceptors in vertebrates, which synapse with bipolar cells (BCs) and horizontal (HCs) cells. This cone synapse is functionally and anatomically complex, connecting to 8 types of depolarizing BCs (DBCs) and 5 types of hyperpolarizing BCs (HBCs) in mice. The dendrites of DBCs and HCs cells make invaginating ribbon synapses with the cone axon terminal, while HBCs form flat synapses with the cone pedicles. The molecular architecture that underpins this organization is relatively poorly understood. To identify new proteins involved in synapse formation and function we used an unbiased proteomic approach and identified LRFN2 (leucine-rich repeat and fibronectin III domain-containing 2) as a component of the DBC signaling complex. LRFN2 is selectively expressed at cone terminals and co-localizes with PNA, and other DBC signalplex members. In LRFN2 deficient mice, the synaptic markers: LRIT3, ELFN2, mGluR6, TRPM1 and GPR179 are properly localized. Similarly, LRFN2 expression and localization is not dependent on these synaptic proteins. In the absence of LRFN2 the cone-mediated photopic electroretinogram b-wave amplitude is reduced at the brightest flash intensities. These data demonstrate that LRFN2 absence compromises normal synaptic transmission between cones and cone DBCs.Significance Statement Signaling between cone photoreceptors and the downstream bipolar cells is critical to normal vision. Cones synapse with 13 different types of bipolar cells forming an invaginating ribbon synapses with 8 types, and flat synapses with 5 types, to form one of the most complex synapses in the brain. In this report a new protein, LRFN2 (leucine-rich repeat and fibronectin III domain-containing 2), was identified that is expressed at the cone synapse. Using Lrfn2 knockout mice we show LRFN2 is required for the normal cone signaling.
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Affiliation(s)
- Nazarul Hasan
- Departments of Biochemistry & Molecular Genetics, University of Louisville, Louisville, Kentucky 40202
- Ophthalmology & Visual Sciences, University of Louisville, Louisville, Kentucky 40202
| | - Ronald G. Gregg
- Departments of Biochemistry & Molecular Genetics, University of Louisville, Louisville, Kentucky 40202
- Ophthalmology & Visual Sciences, University of Louisville, Louisville, Kentucky 40202
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McLaughlin T, Wang G, Medina A, Perkins J, Nihlawi R, Seyfried D, Hu Z, Wang JJ, Zhang SX. Essential Role of XBP1 in Maintaining Photoreceptor Synaptic Integrity in Early Diabetic Retinopathy. Invest Ophthalmol Vis Sci 2023; 64:40. [PMID: 38015176 PMCID: PMC10691399 DOI: 10.1167/iovs.64.14.40] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 11/04/2023] [Indexed: 11/29/2023] Open
Abstract
Purpose Diabetic retinopathy (DR) is a leading cause of blindness in working-age adults characterized by retinal dysfunction and neurovascular degeneration. We previously reported that deletion of X-box binding protein 1 (XBP1) leads to accelerated retinal neurodegeneration in diabetes; however, the mechanisms remain elusive. The goal of this study is to determine the role of XBP1 in the regulation of photoreceptor synaptic integrity in early DR. Methods Diabetes was induced by streptozotocin in retina-specific XBP1 conditional knockout (cKO) or wild-type (WT) mice to generate diabetic cKO (cKO/DM) or WT/DM mice for comparison with nondiabetic cKO (cKO/NDM) and WT/NDM mice. Retinal morphology, structure, and function were assessed by immunohistochemistry, optical coherence tomography, and electroretinogram (ERG) after 3 months of diabetes. The synapses between photoreceptors and bipolar cells were examined by confocal microscopy, and synaptic integrity was quantified using the QUANTOS algorithm. Results We found a thinning of the outer nuclear layer and a decline in the b-wave amplitude in dark- and light-adapted ERG in cKO/DM mice compared to all other groups. In line with these changes, cKO mice showed increased loss of synaptic integrity compared to WT mice, regardless of diabetes status. In searching for candidate molecules responsible for the loss of photoreceptor synaptic integrity in diabetic and XBP1-deficient retinas, we found decreased mRNA and protein levels of DLG4/PSD-95 in cKO/DM retina compared to WT/DM. Conclusions These findings suggest that XBP1 is a crucial regulator in maintaining synaptic integrity and retinal function, possibly through regulation of synaptic scaffold proteins.
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Affiliation(s)
- Todd McLaughlin
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, New York, United States
| | - Grant Wang
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, New York, United States
| | - Andy Medina
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, New York, United States
| | - Jacob Perkins
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, New York, United States
| | - Rhudwan Nihlawi
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, New York, United States
| | - Don Seyfried
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, New York, United States
| | - Zihua Hu
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, New York, United States
- Center for Computational Research, New York State Center of Excellence in Bioinformatics and Life Sciences, State University of New York, Buffalo, New York, United States
| | - Joshua J. Wang
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, New York, United States
- Department of Biochemistry, State University of New York, Buffalo, New York, United States
| | - Sarah X. Zhang
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, New York, United States
- Department of Biochemistry, State University of New York, Buffalo, New York, United States
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Dittrich A, Ramesh G, Jung M, Schmitz F. Rabconnectin-3α/DMXL2 Is Locally Enriched at the Synaptic Ribbon of Rod Photoreceptor Synapses. Cells 2023; 12:1665. [PMID: 37371135 DOI: 10.3390/cells12121665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/08/2023] [Accepted: 06/17/2023] [Indexed: 06/29/2023] Open
Abstract
Ribbon synapses reliably transmit synaptic signals over a broad signalling range. Rod photoreceptor ribbon synapses are capable of transmitting signals generated by the absorption of single photons. The high precision of ribbon synapses emphasizes the need for particularly efficient signalling mechanisms. Synaptic ribbons are presynaptic specializations of ribbon synapses and are anchored to the active zone. Synaptic ribbons bind many synaptic vesicles that are delivered to the active zone for continuous and faithful signalling. In the present study we demonstrate with independent antibodies at the light- and electron microscopic level that rabconnectin-3α (RC3α)-alternative name Dmx-like 2 (DMXL2)-is localized to the synaptic ribbons of rod photoreceptor synapses in the mouse retina. In the brain, RC3α-containing complexes are known to interact with important components of synaptic vesicles, including Rab3-activating/inactivating enzymes, priming proteins and the vesicular H+-ATPase that acidifies the synaptic vesicle lumen to promote full neurotransmitter loading. The association of RC3α/DMXL2 with rod synaptic ribbons of the mouse retina could enable these structures to deliver only fully signalling-competent synaptic vesicles to the active zone thus contributing to reliable synaptic communication.
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Affiliation(s)
- Alina Dittrich
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Girish Ramesh
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
- Institute of Biophysics, Saarland University, 66421 Homburg, Germany
| | - Martin Jung
- Institute of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Frank Schmitz
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
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4
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Townes-Anderson E, Halász É, Sugino I, Davidow AL, Frishman LJ, Fritzky L, Yousufzai FAK, Zarbin M. Injury to Cone Synapses by Retinal Detachment: Differences from Rod Synapses and Protection by ROCK Inhibition. Cells 2023; 12:1485. [PMID: 37296606 PMCID: PMC10253016 DOI: 10.3390/cells12111485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 05/22/2023] [Accepted: 05/24/2023] [Indexed: 06/12/2023] Open
Abstract
Attachment of a detached retina does not always restore vision to pre-injury levels, even if the attachment is anatomically successful. The problem is due in part to long-term damage to photoreceptor synapses. Previously, we reported on damage to rod synapses and synaptic protection using a Rho kinase (ROCK) inhibitor (AR13503) after retinal detachment (RD). This report documents the effects of detachment, reattachment, and protection by ROCK inhibition on cone synapses. Conventional confocal and stimulated emission depletion (STED) microscopy were used for morphological assessment and electroretinograms for functional analysis of an adult pig model of RD. RDs were examined 2 and 4 h after injury or two days later when spontaneous reattachment had occurred. Cone pedicles respond differently than rod spherules. They lose their synaptic ribbons, reduce invaginations, and change their shape. ROCK inhibition protects against these structural abnormalities whether the inhibitor is applied immediately or 2 h after the RD. Functional restoration of the photopic b-wave, indicating cone-bipolar neurotransmission, is also improved with ROCK inhibition. Successful protection of both rod and cone synapses with AR13503 suggests this drug will (1) be a useful adjunct to subretinal administration of gene or stem cell therapies and (2) improve recovery of the injured retina when treatment is delayed.
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Affiliation(s)
- Ellen Townes-Anderson
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA;
| | - Éva Halász
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA;
| | - Ilene Sugino
- Institute of Ophthalmology and Visual Science, Rutgers New Jersey Medical School, 90 Bergen Street, Newark, NJ 07103, USA; (I.S.); (M.Z.)
| | - Amy L. Davidow
- Department of Biostatistics, New York University School of Global Public Health, 708 Broadway, New York, NY 10003, USA;
| | - Laura J. Frishman
- Department of Vision Sciences, College of Optometry, University of Houston, Martin Luther King Blvd, Houston, TX 77204, USA;
| | - Luke Fritzky
- Cellular Imaging and Histology Core, Rutgers New Jersey Medical School, 205 South Orange Avenue, Newark, NJ 07103, USA; (L.F.); (F.A.K.Y.)
| | - Fawad A. K. Yousufzai
- Cellular Imaging and Histology Core, Rutgers New Jersey Medical School, 205 South Orange Avenue, Newark, NJ 07103, USA; (L.F.); (F.A.K.Y.)
| | - Marco Zarbin
- Institute of Ophthalmology and Visual Science, Rutgers New Jersey Medical School, 90 Bergen Street, Newark, NJ 07103, USA; (I.S.); (M.Z.)
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5
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Kilisch M, Gere-Becker M, Wüstefeld L, Bonnas C, Crauel A, Mechmershausen M, Martens H, Götzke H, Opazo F, Frey S. Simple and Highly Efficient Detection of PSD95 Using a Nanobody and Its Recombinant Heavy-Chain Antibody Derivatives. Int J Mol Sci 2023; 24:ijms24087294. [PMID: 37108454 PMCID: PMC10138605 DOI: 10.3390/ijms24087294] [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: 03/16/2023] [Revised: 04/03/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
The post-synaptic density protein 95 (PSD95) is a crucial scaffolding protein participating in the organization and regulation of synapses. PSD95 interacts with numerous molecules, including neurotransmitter receptors and ion channels. The functional dysregulation of PSD95 as well as its abundance and localization has been implicated with several neurological disorders, making it an attractive target for developing strategies able to monitor PSD95 accurately for diagnostics and therapeutics. This study characterizes a novel camelid single-domain antibody (nanobody) that binds strongly and with high specificity to rat, mouse, and human PSD95. This nanobody allows for more precise detection and quantification of PSD95 in various biological samples. We expect that the flexibility and unique performance of this thoroughly characterized affinity tool will help to further understand the role of PSD95 in normal and diseased neuronal synapses.
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Affiliation(s)
- Markus Kilisch
- NanoTag Biotechnologies GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
| | - Maja Gere-Becker
- NanoTag Biotechnologies GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
| | - Liane Wüstefeld
- Synaptic Systems GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
| | - Christel Bonnas
- Synaptic Systems GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
| | - Alexander Crauel
- NanoTag Biotechnologies GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
| | - Maja Mechmershausen
- NanoTag Biotechnologies GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
| | - Henrik Martens
- Synaptic Systems GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
| | - Hansjörg Götzke
- NanoTag Biotechnologies GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
| | - Felipe Opazo
- NanoTag Biotechnologies GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
- Institute of Neuro- and Sensory Physiology, University Medical Center Göttingen, 37073 Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration (BIN), University of Göttingen Medical Center, 37075 Göttingen, Germany
| | - Steffen Frey
- NanoTag Biotechnologies GmbH, Rudolf-Wissell-Straβe 28a, 37079 Göttingen, Germany
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Harris SC, Dunn FA. Asymmetric retinal direction tuning predicts optokinetic eye movements across stimulus conditions. eLife 2023; 12:e81780. [PMID: 36930180 PMCID: PMC10023158 DOI: 10.7554/elife.81780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 02/02/2023] [Indexed: 03/18/2023] Open
Abstract
Across species, the optokinetic reflex (OKR) stabilizes vision during self-motion. OKR occurs when ON direction-selective retinal ganglion cells (oDSGCs) detect slow, global image motion on the retina. How oDSGC activity is integrated centrally to generate behavior remains unknown. Here, we discover mechanisms that contribute to motion encoding in vertically tuned oDSGCs and leverage these findings to empirically define signal transformation between retinal output and vertical OKR behavior. We demonstrate that motion encoding in vertically tuned oDSGCs is contrast-sensitive and asymmetric for oDSGC types that prefer opposite directions. These phenomena arise from the interplay between spike threshold nonlinearities and differences in synaptic input weights, including shifts in the balance of excitation and inhibition. In behaving mice, these neurophysiological observations, along with a central subtraction of oDSGC outputs, accurately predict the trajectories of vertical OKR across stimulus conditions. Thus, asymmetric tuning across competing sensory channels can critically shape behavior.
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Affiliation(s)
- Scott C Harris
- Department of Ophthalmology, University of California, San FranciscoSan FranciscoUnited States
- Neuroscience Graduate Program, University of California, San FranciscoSan FranciscoUnited States
| | - Felice A Dunn
- Department of Ophthalmology, University of California, San FranciscoSan FranciscoUnited States
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7
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da Costa Souza F, Grodzki ACG, Morgan RK, Zhang Z, Taha AY, Lein PJ. Oxidized linoleic acid metabolites regulate neuronal morphogenesis in vitro. Neurochem Int 2023; 164:105506. [PMID: 36758902 PMCID: PMC10495953 DOI: 10.1016/j.neuint.2023.105506] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 02/04/2023] [Accepted: 02/06/2023] [Indexed: 02/10/2023]
Abstract
Linoleic acid (LA, 18:2n-6) is an essential nutrient for optimal infant growth and brain development. The effects of LA in the brain are thought to be mediated by oxygenated metabolites of LA known as oxidized LA metabolites (OXLAMs), but evidence is lacking to directly support this hypothesis. This study investigated whether OXLAMs modulate key neurodevelopmental processes including axon outgrowth, dendritic arborization, cell viability and synaptic connectivity. Primary cortical neuron-glia co-cultures from postnatal day 0-1 male and female rats were exposed for 48h to the following OXLAMs: 1) 13-hydroxyoctadecadienoic acid (13-HODE); 2) 9-hydroxyoctadecadienoic acid (9-HODE); 3) 9,10-dihydroxyoctadecenoic acid (9,10-DiHOME); 4) 12(13)-epoxyoctadecenoic acid (12(13)-EpOME); 5) 9,10,13-trihydroxyoctadecenoic acid (9,10,13-TriHOME); 6) 9-oxo-octadecadienoic acid (9-OxoODE); and 7) 12,13-dihydroxyoctadecenoic acid (12,13-DiHOME). Axonal outgrowth, evaluated by Tau-1 immunostaining, was increased by 9-HODE, but decreased by 12,13-DiHOME in male but not female neurons. Dendrite arborization, evaluated by MAP2B-eGFP expression, was affected by 9-HODE, 9-OxoODE, and 12(13)-EpOME in male neurons and, by 12(13)-EpOME in female neurons. Neither cell viability nor synaptic connectivity were significantly altered by OXLAMs. Overall, this study shows select OXLAMs modulate neuron morphology in a sex-dependent manner, with male neurons being more susceptible.
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Affiliation(s)
- Felipe da Costa Souza
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, University of California, Davis, CA, USA; Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
| | - Ana Cristina G Grodzki
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
| | - Rhianna K Morgan
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
| | - Zhichao Zhang
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, University of California, Davis, CA, USA.
| | - Ameer Y Taha
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, University of California, Davis, CA, USA.
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
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8
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Microglia in Cultured Porcine Retina: Qualitative Immunohistochemical Analyses of Reactive Microglia in the Outer Retina. Int J Mol Sci 2023; 24:ijms24010871. [PMID: 36614320 PMCID: PMC9820911 DOI: 10.3390/ijms24010871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/26/2022] [Accepted: 12/29/2022] [Indexed: 01/05/2023] Open
Abstract
A late stage of several retinal disorders is retinal detachment, a complication that results in rapid photoreceptor degeneration and synaptic damages. Experimental retinal detachment in vivo is an invasive and complicated method performed on anesthetized animals. As retinal detachment may result in visual impairment and blindness, research is of fundamental importance for understanding degenerative processes. Both morphological and ethical issues make the porcine retina a favorable organotypic model for studies of the degenerative processes that follow retinal detachment. In the cultured retina, photoreceptor degeneration and synaptic injuries develop rapidly and correlate with resident microglial cells' transition into a reactive phenotype. In this immunohistochemical study, we have begun to analyze the transition of subsets of reactive microglia which are known to localize close to the outer plexiform layer (OPL) in degenerating in vivo and in vitro retina. Biomarkers for reactive microglia included P2Ry12, CD63 and CD68 and the general microglial markers were CD11b, Iba1 and isolectin B4 (IB4). The reactive microglia markers labeled microglia subpopulations, suggesting that protective or harmful reactive microglia may be present simultaneously in the injured retina. Our findings support the usage of porcine retina cultures for studies of photoreceptor injuries related to retinal detachment.
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Zhai RG. The Architecture of the Presynaptic Release Site. ADVANCES IN NEUROBIOLOGY 2023; 33:1-21. [PMID: 37615861 DOI: 10.1007/978-3-031-34229-5_1] [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: 08/25/2023]
Abstract
The architecture of the presynaptic release site is exquisitely designed to facilitate and regulate synaptic vesicle exocytosis. With the identification of some of the building blocks of the active zone and the advent of super resolution imaging techniques, we are beginning to understand the morphological and functional properties of synapses in great detail. Presynaptic release sites consist of the plasma membrane, the cytomatrix, and dense projections. These three components are morphologically distinct but intimately connected with each other and with postsynaptic specializations, ensuring the fidelity of synaptic vesicle tethering, docking, and fusion, as well as signal detection. Although the morphology and molecular compositions of active zones may vary among species, tissues, and cells, global architectural design of the release sites is highly conserved.
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Affiliation(s)
- R Grace Zhai
- Department of Molecular and Cellular Pharmacology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL, USA.
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Ballmer D, Tardat M, Ortiz R, Graff-Meyer A, Ozonov E, Genoud C, Peters A, Fanourgakis G. HP1 proteins regulate nucleolar structure and function by secluding pericentromeric constitutive heterochromatin. Nucleic Acids Res 2022; 51:117-143. [PMID: 36533441 PMCID: PMC9841413 DOI: 10.1093/nar/gkac1159] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/29/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Nucleoli are nuclear compartments regulating ribosome biogenesis and cell growth. In embryonic stem cells (ESCs), nucleoli containing transcriptionally active ribosomal genes are spatially separated from pericentromeric satellite repeat sequences packaged in largely repressed constitutive heterochromatin (PCH). To date, mechanisms underlying such nuclear partitioning and the physiological relevance thereof are unknown. Here we show that repressive chromatin at PCH ensures structural integrity and function of nucleoli during cell cycle progression. Loss of heterochromatin proteins HP1α and HP1β causes deformation of PCH, with reduced H3K9 trimethylation (H3K9me3) and HP1γ levels, absence of H4K20me3 and upregulated major satellites expression. Spatially, derepressed PCH aberrantly associates with nucleoli accumulating severe morphological defects during S/G2 cell cycle progression. Hp1α/β deficiency reduces cell proliferation, ribosomal RNA biosynthesis and mobility of Nucleophosmin, a major nucleolar component. Nucleolar integrity and function require HP1α/β proteins to be recruited to H3K9me3-marked PCH and their ability to dimerize. Correspondingly, ESCs deficient for both Suv39h1/2 H3K9 HMTs display similar nucleolar defects. In contrast, Suv4-20h1/2 mutant ESCs lacking H4K20me3 at PCH do not. Suv39h1/2 and Hp1α/β deficiency-induced nucleolar defects are reminiscent of those defining human ribosomopathy disorders. Our results reveal a novel role for SUV39H/HP1-marked repressive constitutive heterochromatin in regulating integrity, function and physiology of nucleoli.
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Affiliation(s)
- Daniel Ballmer
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland,Faculty of Sciences, University of Basel, 4056 Basel, Switzerland
| | - Mathieu Tardat
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Raphael Ortiz
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Alexandra Graff-Meyer
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Evgeniy A Ozonov
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Christel Genoud
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | | | - Grigorios Fanourgakis
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
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11
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Van Hook MJ. Influences of Glaucoma on the Structure and Function of Synapses in the Visual System. Antioxid Redox Signal 2022; 37:842-861. [PMID: 35044228 PMCID: PMC9587776 DOI: 10.1089/ars.2021.0253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 12/31/2021] [Indexed: 11/12/2022]
Abstract
Significance: Glaucoma is an age-related neurodegenerative disorder of the visual system associated with sensitivity to intraocular pressure (IOP). It is the leading irreversible cause of vision loss worldwide, and vision loss results from damage and dysfunction of the retinal output neurons known as retinal ganglion cells (RGCs). Recent Advances: Elevated IOP and optic nerve injury triggers pruning of RGC dendrites, altered morphology of excitatory inputs from presynaptic bipolar cells, and disrupted RGC synaptic function. Less is known about RGC outputs, although evidence to date indicates that glaucoma is associated with altered mitochondrial and synaptic structure and function in RGC-projection targets in the brain. These early functional changes likely contribute to vision loss and might be a window into early diagnosis and treatment. Critical Issues: Glaucoma affects different RGC populations to varying extents and along distinct time courses. The influence of glaucoma on RGC synaptic function as well as the mechanisms underlying these effects remain to be determined. Since RGCs are an especially energetically demanding population of neurons, altered intracellular axon transport of mitochondria and mitochondrial function might contribute to RGC synaptic dysfunction in the retina and brain as well as RGC vulnerability in glaucoma. Future Directions: The mechanisms underlying differential RGC vulnerability remain to be determined. Moreover, the timing and mechanisms of RGCs synaptic dysfunction and degeneration will provide valuable insight into the disease process in glaucoma. Future work will be able to capitalize on these findings to better design diagnostic and therapeutic approaches to detect disease and prevent vision loss. Antioxid. Redox Signal. 37, 842-861.
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Affiliation(s)
- Matthew J. Van Hook
- Department of Ophthalmology & Visual Science and Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Cellular & Integrative Physiology, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
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12
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Albrecht NE, Jiang D, Akhanov V, Hobson R, Speer CM, Robichaux MA, Samuel MA. Rapid 3D-STORM imaging of diverse molecular targets in tissue. CELL REPORTS METHODS 2022; 2:100253. [PMID: 35880013 PMCID: PMC9308169 DOI: 10.1016/j.crmeth.2022.100253] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 04/22/2022] [Accepted: 06/17/2022] [Indexed: 11/25/2022]
Abstract
Fine-scale molecular architecture is critical for nervous system and other biological functions. Methods to visualize these nanoscale structures would benefit from enhanced accessibility, throughput, and tissue compatibility. Here, we report RAIN-STORM, a rapid and scalable nanoscopic imaging optimization approach that improves three-dimensional visualization for subcellular targets in tissue at depth. RAIN-STORM uses conventional tissue samples and readily available reagents and is suitable for commercial instrumentation. To illustrate the efficacy of RAIN-STORM, we utilized the retina. We show that RAIN-STORM imaging is versatile and provide 3D nanoscopic data for over 20 synapse, neuron, glia, and vasculature targets. Sample preparation is also rapid, with a 1-day turnaround from tissue to image, and parameters are suitable for multiple tissue sources. Finally, we show that this method can be applied to clinical samples to reveal nanoscale features of human cells and synapses. RAIN-STORM thus paves the way for high-throughput studies of nanoscopic targets in tissue.
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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
| | - 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
| | - Viktor Akhanov
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Robert Hobson
- Bruker Nano Surfaces Division, Salt Lake City, UT 84108, USA
| | - Colenso M. Speer
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Michael A. Robichaux
- Departments of Ophthalmology and Biochemistry, West Virginia University, Morgantown, WV 26506, 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
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13
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Impact of Primary RPE Cells in a Porcine Organotypic Co-Cultivation Model. Biomolecules 2022; 12:biom12070990. [PMID: 35883547 PMCID: PMC9313304 DOI: 10.3390/biom12070990] [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: 04/22/2022] [Revised: 07/04/2022] [Accepted: 07/13/2022] [Indexed: 12/10/2022] Open
Abstract
The pathological events of age-related macular degeneration are characterized by degenerative processes involving the photoreceptor cells, retinal pigment epithelium (RPE), and the Bruch's membrane as well as choroidal alterations. To mimic in vivo interactions between photoreceptor cells and RPE cells ex vivo, complex models are required. Hence, the aim of this study was to establish a porcine organotypic co-cultivation model and enlighten the interactions of photoreceptor and RPE cells, with a special emphasis on potential neuroprotective effects. Porcine neuroretina explants were cultured with primary porcine RPE cells (ppRPE) or medium derived from these cells (=conditioned medium). Neuroretina explants cultured alone served as controls. After eight days, RT-qPCR and immunohistology were performed to analyze photoreceptors, synapses, macroglia, microglia, complement factors, and pro-inflammatory cytokines (e.g., IL1B, IL6, TNF) in the neuroretina samples. The presence of ppRPE cells preserved photoreceptors, whereas synaptical density was unaltered. Interestingly, on an immunohistological as well as on an mRNA level, microglia and complement factors were comparable in all groups. Increased IL6 levels were noted in ppRPE and conditioned medium samples, while TNF was only upregulated in the ppRPE group. IL1B was elevated in conditioned medium samples. In conclusion, a co-cultivation of ppRPE cells and neuroretina seem to have beneficial effects on the neuroretina, preserving photoreceptors and maintaining synaptic vesicles in vitro. This organotypic co-cultivation model can be used to investigate the complex interactions between the retina and RPE cells, gain further insight into neurodegenerative pathomechanisms occurring in retinal diseases, and evaluate potential therapeutics.
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14
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Wagner N, Safaei A, Vogt PA, Gammel MR, Dick HB, Schnichels S, Joachim SC. Coculture of ARPE-19 Cells and Porcine Neural Retina as an Ex Vivo Retinal Model. Altern Lab Anim 2022; 50:27-44. [PMID: 35302924 DOI: 10.1177/02611929221082662] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Neural retinal organ cultures are used to investigate ocular pathomechanisms. However, these cultures lack the essential retinal pigment epithelium (RPE) cells, which are part of the actual in vivo retina. To simulate a more realistic ex vivo model, porcine neural retina explants were cocultured with ARPE-19 cells (ARPE-19 group), which are derived from human RPE. To identify whether the entire cells or just the cell factors are necessary, in a second experimental group, porcine neural retina explants were cultured with medium derived from ARPE-19 cells (medium group). Individually cultured neural retina explants served as controls (control group). After 8 days, all neural retinas were analysed to evaluate retinal thickness, photoreceptors, microglia, complement factors and synapses (n = 6-8 per group). The neural retina thickness in the ARPE-19 group was significantly better preserved than in the control group (p = 0.031). Also, the number of L-cones was higher in the ARPE-19 group, as compared to the control group (p < 0.001). Furthermore, the ARPE-19 group displayed an increased presynaptic glutamate uptake (determined via vGluT1 labelling) and enhanced post-synaptic density (determined via PSD-95 labelling). Combined Iba1 and iNOS detection revealed only minor effects of ARPE-19 cells on microglial activity, with a slight downregulation of total microglia activity apparent in the medium group. Likewise, only minor beneficial effects on photoreceptors and synaptic structure were found in the medium group. This novel system offers the opportunity to investigate interactions between the neural retina and RPE cells, and suggests that the inclusion of a RPE feeder layer has beneficial effects on the ex vivo maintenance of neural retina. By modifying the culture conditions, this coculture model allows a better understanding of photoreceptor death and photoreceptor-RPE cell interactions in retinal diseases.
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Affiliation(s)
- Natalie Wagner
- Experimental Eye Research Institute, University Eye Hospital, 9142Ruhr-University Bochum, Germany
| | - Armin Safaei
- Experimental Eye Research Institute, University Eye Hospital, 9142Ruhr-University Bochum, Germany
| | - Pia A Vogt
- Experimental Eye Research Institute, University Eye Hospital, 9142Ruhr-University Bochum, Germany
| | - Maurice R Gammel
- Experimental Eye Research Institute, University Eye Hospital, 9142Ruhr-University Bochum, Germany
| | - H Burkhard Dick
- Experimental Eye Research Institute, University Eye Hospital, 9142Ruhr-University Bochum, Germany
| | - Sven Schnichels
- Centre for Ophthalmology Tübingen, University Eye Hospital Tübingen, Germany
| | - Stephanie C Joachim
- Experimental Eye Research Institute, University Eye Hospital, 9142Ruhr-University Bochum, Germany
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15
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Shankhwar S, Schwarz K, Katiyar R, Jung M, Maxeiner S, Südhof TC, Schmitz F. RIBEYE B-Domain Is Essential for RIBEYE A-Domain Stability and Assembly of Synaptic Ribbons. Front Mol Neurosci 2022; 15:838311. [PMID: 35153673 PMCID: PMC8831697 DOI: 10.3389/fnmol.2022.838311] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/03/2022] [Indexed: 01/17/2023] Open
Abstract
Synaptic ribbons are presynaptic specializations that define eponymous ribbon synapses. Synaptic ribbons are largely composed of RIBEYE, a protein containing an N-terminal A-domain and a carboxyterminal B-domain that is identical with CtBP2, a NAD(H)-binding transcriptional co-repressor. Previously we showed that synaptic ribbons are completely absent in RIBEYE knockout mice in which the RIBEYE A-domain-encoding exon had been deleted, but CtBP2 is still made, demonstrating that the A-domain is required for synaptic ribbon assembly. In the present study, we asked whether the RIBEYE B-domain also has an essential role in the assembly of synaptic ribbons. For this purpose, we made use of RIBEYE knockin mice in which the RIBEYE B-domain was replaced by a fluorescent protein domain, whereas the RIBEYE A-domain was retained unchanged. We found that replacing the RIBEYE B-domain with a fluorescent protein module destabilizes the resulting hybrid protein and causes a complete loss of synaptic ribbons. Our results thus demonstrate an essential role of the RIBEYE B-domain in enabling RIBEYE assembly into synaptic ribbons, reinforcing the notion that RIBEYE is the central organizer of synaptic ribbons.
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Affiliation(s)
- Soni Shankhwar
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
- *Correspondence: Soni Shankhwar Frank Schmitz
| | - Karin Schwarz
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
| | - Rashmi Katiyar
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
| | - Martin Jung
- Institute of Medical Biochemistry and Molecular Biology, Saarland University, Medical School, Homburg, Germany
| | - Stephan Maxeiner
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
| | - Thomas C. Südhof
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, United States
| | - Frank Schmitz
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
- *Correspondence: Soni Shankhwar Frank Schmitz
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16
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Sun X, Li L, Wu B, Ge J, Zheng Y, Yu T, Zhou L, Zhang T, Yang A, Liu Z. Cell type diversity in scallop adductor muscles revealed by single-cell RNA-Seq. Genomics 2021; 113:3582-3598. [PMID: 34425225 DOI: 10.1016/j.ygeno.2021.08.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 07/26/2021] [Accepted: 08/18/2021] [Indexed: 11/28/2022]
Abstract
Studies on cell atlas in marine invertebrates provide a better understanding of cell types, stem cell maintenance, and lineages of cell differentiation. To investigate the molecular features of various cell types in molluscan muscles, we performed single-cell RNA sequencing (scRNA-seq) to map cell types in scallop adductor muscles. We uncovered the cell type-specific features of 20 cell clusters defined by the expression of multiple specific molecular markers. These cell clusters are mainly classified into four broad classes, including mesenchymal stem cells, muscle cells, neurons, and haemolymph cells. In particular, we identified a diverse repertoire of neurons in the striated adductor muscle, but not in the smooth muscle. We further reconstructed the cell differentiation events using all the cell clusters by single-cell pseudotemporal trajectories. By integrating dual BrdU-PCNA immunodetection, neuron-specific staining and electron microscopy observation, we showed the spatial distribution of mesenchymal stem cells and neurons in striated adductor muscle of scallops. The present findings will not only be useful to address the cell type-specific gene expression profiles in scallop muscles, but also provide valuable resources for cross-species comparison of marine organisms.
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Affiliation(s)
- Xiujun Sun
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266071, China
| | - Li Li
- Marine Biology Institute of Shandong Province, Qingdao 266104, China
| | - Biao Wu
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266071, China
| | - Jianlong Ge
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266071, China
| | - Yanxin Zheng
- Changdao Enhancement and Experiment Station, Chinese Academy of Fishery Sciences, Yantai 265800, China
| | - Tao Yu
- Changdao Enhancement and Experiment Station, Chinese Academy of Fishery Sciences, Yantai 265800, China
| | - Liqing Zhou
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266071, China
| | - Tianshi Zhang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266071, China
| | - Aiguo Yang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266071, China
| | - Zhihong Liu
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266071, China.
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17
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Xu S, Zhang P, Zhang M, Wang X, Li G, Xu G, Ni Y. Synaptic changes and the response of microglia in a light-induced photoreceptor degeneration model. Mol Vis 2021; 27:206-220. [PMID: 33967574 PMCID: PMC8100860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 04/29/2021] [Indexed: 11/15/2022] Open
Abstract
Purpose To explore synaptic changes and the response of microglia in a light-induced photoreceptor degeneration model. Methods Sprague-Dawley rats were euthanized 1 h, 1 day, 3 days, 7 days, and 14 days after being exposed to intense blue light for 24 h. Hematoxylin and eosin (H&E) and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining were used to evaluate changes in the outer nuclear layer (ONL). Transmission electron microscopy (TEM) was applied to observe the ultrastructural changes in the synapses between the photoreceptors and second-order neurons. Western blotting was conducted to evaluate specific proteins, including postsynaptic density-95 (PSD-95), metabotropic glutamate receptor 6 (mGluR6), synapsin I, and synaptophysin. Immunofluorescence of CD11b and PKC-α or mGluR6 was used to explore the spatial relationships between microglial processes and synaptic elements. Immunoelectron microscopy of PSD-95 was performed to further confirm its engulfment of synaptic materials. Results H&E and TUNEL staining showed that the thickness of the ONL decreased markedly, and the number of apoptotic photoreceptors peaked at day 1. TEM revealed darkened photoreceptor terminals and that ribbons of them were floating in the cytoplasm, coinciding with the downregulation of PSD-95 and mGluR6. Downstream synaptic protein synapsin I and synaptophysin exhibited upregulation in the inner plexiform layer. Activated microglia migrated to the outer retina, and their processes were found in close proximity to synapses in the outer plexiform layer under light and electron microscopy levels. Double immunostaining of CD11b and mGluR6 showed colocalization. PSD-95-immunoreactive electron-dense materials were observed inside the microglia suggesting engulfment of synaptic components. Conclusions The study showed that there are early synaptic impairment and late compensatory changes in downstream synapses in this photic injury model. Activated microglia touched and directly engulfed synaptic materials. Microglia may play a role or a partial role in synaptic changes.
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Affiliation(s)
- Sisi Xu
- Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China,Key NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Peijun Zhang
- Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China,Key NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Meng Zhang
- Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China,Key NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Xin Wang
- Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China,Key NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Gang Li
- Research Center, Eye & ENT Hospital of Fudan University, Shanghai, China
| | - Gezhi Xu
- Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China,Key NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Yingqin Ni
- Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China,Key NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
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18
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Burger CA, Jiang D, Mackin RD, Samuel MA. Development and maintenance of vision's first synapse. Dev Biol 2021; 476:218-239. [PMID: 33848537 DOI: 10.1016/j.ydbio.2021.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/02/2021] [Accepted: 04/03/2021] [Indexed: 12/21/2022]
Abstract
Synapses in the outer retina are the first information relay points in vision. Here, photoreceptors form synapses onto two types of interneurons, bipolar cells and horizontal cells. Because outer retina synapses are particularly large and highly ordered, they have been a useful system for the discovery of mechanisms underlying synapse specificity and maintenance. Understanding these processes is critical to efforts aimed at restoring visual function through repairing or replacing neurons and promoting their connectivity. We review outer retina neuron synapse architecture, neural migration modes, and the cellular and molecular pathways that play key roles in the development and maintenance of these connections. We further discuss how these mechanisms may impact connectivity in the retina.
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Affiliation(s)
- Courtney A Burger
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Danye Jiang
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Robert D Mackin
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Melanie A Samuel
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA.
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19
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Fu Z, Qiu C, Cagnone G, Tomita Y, Huang S, Cakir B, Kotoda Y, Allen W, Bull E, Akula JD, Joyal JS, Hellström A, Talukdar S, Smith LEH. Retinal glial remodeling by FGF21 preserves retinal function during photoreceptor degeneration. iScience 2021; 24:102376. [PMID: 33937726 PMCID: PMC8079476 DOI: 10.1016/j.isci.2021.102376] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/13/2021] [Accepted: 03/25/2021] [Indexed: 12/18/2022] Open
Abstract
The group of retinal degenerations, retinitis pigmentosa (RP), comprises more than 150 genetic abnormalities affecting photoreceptors. Finding degenerative pathways common to all genetic abnormalities may allow general treatment such as neuroprotection. Neuroprotection may include enhancing the function of cells that directly support photoreceptors, retinal pigment epithelial cells, and Müller glia. Treatment with fibroblast growth factor 21 (FGF21), a neuroprotectant, from postnatal week 4-10, during rod and cone loss in P23H mice (an RP model) with retinal degeneration, preserved photoreceptor function and normalized Müller glial cell morphology. Single-cell transcriptomics of retinal cells showed that FGF21 receptor Fgfr1 was specifically expressed in Müller glia/astrocytes. Of all retinal cells, FGF21 predominantly affected genes in Müller glia/astrocytes with increased expression of axon development and synapse formation pathway genes. Therefore, enhancing retinal glial axon and synapse formation with neurons may preserve retinal function in RP and may suggest a general therapeutic approach for retinal degenerative diseases.
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Affiliation(s)
- Zhongjie Fu
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.,The Manton Center for Orphan Disease, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Chenxi Qiu
- Department of Medicine, Division of Translational Therapeutics, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Gael Cagnone
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, Qc H3A 0C4, Canada.,Department of Pharmacology and Therapeutics, McGill University, Montreal, Qc H3A 0C4, Canada
| | - Yohei Tomita
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Shuo Huang
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Bertan Cakir
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Yumi Kotoda
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - William Allen
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Edward Bull
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - James D Akula
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jean-Sébastien Joyal
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, Qc H3A 0C4, Canada.,Department of Pharmacology and Therapeutics, McGill University, Montreal, Qc H3A 0C4, Canada
| | - Ann Hellström
- Section for Ophthalmology, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg 405 30, Sweden
| | - Saswata Talukdar
- Cardiometabolic Diseases, Merck Research Laboratories, 33 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Lois E H Smith
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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20
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O'Hara-Wright M, Gonzalez-Cordero A. Retinal organoids: a window into human retinal development. Development 2020; 147:147/24/dev189746. [PMID: 33361444 PMCID: PMC7774906 DOI: 10.1242/dev.189746] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Retinal development and maturation are orchestrated by a series of interacting signalling networks that drive the morphogenetic transformation of the anterior developing brain. Studies in model organisms continue to elucidate these complex series of events. However, the human retina shows many differences from that of other organisms and the investigation of human eye development now benefits from stem cell-derived organoids. Retinal differentiation methods have progressed from simple 2D adherent cultures to self-organising micro-physiological systems. As models of development, these have collectively offered new insights into the previously unexplored early development of the human retina and informed our knowledge of the key cell fate decisions that govern the specification of light-sensitive photoreceptors. Although the developmental trajectories of other retinal cell types remain more elusive, the collation of omics datasets, combined with advanced culture methodology, will enable modelling of the intricate process of human retinogenesis and retinal disease in vitro. Summary: Retinal organoid systems derived from human pluripotent stem cells are micro-physiological systems that offer new insights into previously unexplored human retina development.
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Affiliation(s)
- Michelle O'Hara-Wright
- Stem Cell Medicine Group, Children's Medical Research Institute, University of Sydney, Westmead, 2145, NSW, Australia.,School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Westmead, 2145, NSW, Australia
| | - Anai Gonzalez-Cordero
- Stem Cell Medicine Group, Children's Medical Research Institute, University of Sydney, Westmead, 2145, NSW, Australia .,School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Westmead, 2145, NSW, Australia
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21
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Mukherjee A, Katiyar R, Dembla E, Dembla M, Kumar P, Belkacemi A, Jung M, Beck A, Flockerzi V, Schwarz K, Schmitz F. Disturbed Presynaptic Ca 2+ Signaling in Photoreceptors in the EAE Mouse Model of Multiple Sclerosis. iScience 2020; 23:101830. [PMID: 33305185 PMCID: PMC7711289 DOI: 10.1016/j.isci.2020.101830] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 10/10/2020] [Accepted: 11/16/2020] [Indexed: 02/06/2023] Open
Abstract
Multiple sclerosis (MS) is a demyelinating disease caused by an auto-reactive immune system. Recent studies also demonstrated synapse dysfunctions in MS patients and MS mouse models. We previously observed decreased synaptic vesicle exocytosis in photoreceptor synapses in the EAE mouse model of MS at an early, preclinical stage. In the present study, we analyzed whether synaptic defects are associated with altered presynaptic Ca2+ signaling. Using high-resolution immunolabeling, we found a reduced signal intensity of Cav-channels and RIM2 at active zones in early, preclinical EAE. In line with these morphological alterations, depolarization-evoked increases of presynaptic Ca2+ were significantly smaller. In contrast, basal presynaptic Ca2+ was elevated. We observed a decreased expression of Na+/K+-ATPase and plasma membrane Ca2+ ATPase 2 (PMCA2), but not PMCA1, in photoreceptor terminals of EAE mice that could contribute to elevated basal Ca2+. Thus, complex Ca2+ signaling alterations contribute to synaptic dysfunctions in photoreceptors in early EAE. Less Cav-channels and RIM2 at the active zones of EAE photoreceptor synapses Decreased depolarization-evoked Ca2+-responses in EAE photoreceptor synapses Elevated basal, resting Ca2+ levels in preclinical EAE photoreceptor terminals Decreased expression of PMCA2 and Na+/K+-ATPase in EAE photoreceptor synapses
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Affiliation(s)
- Amrita Mukherjee
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Rashmi Katiyar
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Ekta Dembla
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Mayur Dembla
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Praveen Kumar
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Anouar Belkacemi
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Martin Jung
- Institute of Medical Biochemistry and Molecular Biology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Andreas Beck
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Veit Flockerzi
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Karin Schwarz
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Frank Schmitz
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
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22
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Oliver EE, Hughes EK, Puckett MK, Chen R, Lowther WT, Howlett AC. Cannabinoid Receptor Interacting Protein 1a (CRIP1a) in Health and Disease. Biomolecules 2020; 10:biom10121609. [PMID: 33261012 PMCID: PMC7761089 DOI: 10.3390/biom10121609] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 12/15/2022] Open
Abstract
Endocannabinoid signaling depends upon the CB1 and CB2 cannabinoid receptors, their endogenous ligands anandamide and 2-arachidonoylglycerol, and intracellular proteins that mediate responses via the C-terminal and other intracellular receptor domains. The CB1 receptor regulates and is regulated by associated G proteins predominantly of the Gi/o subtypes, β-arrestins 1 and 2, and the cannabinoid receptor-interacting protein 1a (CRIP1a). Evidence for a physiological role for CRIP1a is emerging as data regarding the cellular localization and function of CRIP1a are generated. Here we summarize the neuronal distribution and role of CRIP1a in endocannabinoid signaling, as well as discuss investigations linking CRIP1a to development, vision and hearing sensory systems, hippocampus and seizure regulation, and psychiatric disorders including schizophrenia. We also examine the genetic and epigenetic association of CRIP1a within a variety of cancer subtypes. This review provides evidence upon which to base future investigations on the function of CRIP1a in health and disease.
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Affiliation(s)
- Emily E. Oliver
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
- Department of Biochemistry and Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 20157, USA;
| | - Erin K. Hughes
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
- Department of Biochemistry and Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 20157, USA;
| | - Meaghan K. Puckett
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
| | - Rong Chen
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
| | - W. Todd Lowther
- Department of Biochemistry and Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 20157, USA;
| | - Allyn C. Howlett
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
- Correspondence: ; Tel.: +1-336-716-8545
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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: 21] [Impact Index Per Article: 5.3] [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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Loss of the ER membrane protein complex subunit Emc3 leads to retinal bipolar cell degeneration in aged mice. PLoS One 2020; 15:e0238435. [PMID: 32886670 PMCID: PMC7473584 DOI: 10.1371/journal.pone.0238435] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 08/17/2020] [Indexed: 02/05/2023] Open
Abstract
The endoplasmic reticulum (ER) membrane protein complex (EMC) is a conserved protein complex involved in inserting the transmembrane domain of membrane proteins into membranes in the ER. EMC3 is an essential component of EMC and is important for rhodopsin synthesis in photoreceptor cells. However, the in vivo function of Emc3 in bipolar cells (BCs) has not been determined. To explore the role of Emc3 in BCs, we generated a BC-specific Emc3 knockout mouse model (named Emc3 cKO) using the Purkinje cell protein 2 (Pcp2) Cre line. Although normal electroretinography (ERG) b-waves were observed in Emc3 cKO mice at 6 months of age, Emc3 cKO mice exhibited reduced b-wave amplitudes at 12 months of age, as determined by scotopic and photopic ERG, and progressive death of BCs, whereas the ERG a-wave amplitudes were preserved. PKCa staining of retinal cryosections from Emc3 cKO mice revealed death of rod BCs. Loss of Emc3 led to the presence of the synaptic protein mGLuR6 in the outer nuclear layer (ONL). Immunostaining analysis of presynaptic protein postsynaptic density protein 95 (PSD95) revealed rod terminals retracted to the ONL in Emc3 cKO mice at 12 months of age. In addition, deletion of Emc3 resulted in elevated glial fibrillary acidic protein, indicating reactive gliosis in the retina. Our data demonstrate that loss of Emc3 in BCs leads to decreased ERG response, increased astrogliosis and disruption of the retinal inner nuclear layer in mice of 12 months of age. Taken together, our studies indicate that Emc3 is not required for the development of BCs but is important for long-term survival of BCs.
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Johansson K, Svensson LA, Mohlin C. Morphological analyzes of microglia heterogeneity and dynamics during photoreceptor degeneration in vitro: Presumptive dark microglia in porcine retina. Exp Eye Res 2020; 200:108217. [PMID: 32896534 DOI: 10.1016/j.exer.2020.108217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 08/31/2020] [Accepted: 09/01/2020] [Indexed: 11/18/2022]
Abstract
In the adult retina, ramifying microglia interact with the outer plexiform layer (OPL) monitoring the synaptic integrity between photoreceptors and post-synaptic target cells. Microglia are reactive during photoreceptor diseases, but their disease-related function(s) are not fully understood. Retinal explant cultures are model systems used to study degenerative events including photoreceptor degeneration and gliosis. Our culture paradigm, with adult porcine retinas subjected to coculture with human A-retinal pigment epithelia-19 (ARPE) cells, is an experimental approach resulting in improved photoreceptor survival and reduced gliosis. Under the in vitro pathological conditions with photoreceptor degeneration, reactive Iba1-and CD11b-immunoreactive microglia and their processes positioned in proximity with the OPL and among photoreceptor outer segments. Coculture for 3 days with ARPE-cells resulted in a significantly increased density of microglia at the OPL. After 5 days of culture, the density of microglia at the OPL was similar between coculture and control specimens. Electron microscopy revealed the presence of two subtypes of microglia: one exhibiting a dark nucleus and cytosol with dilated endoplasmic reticulum, vacuoles, endosomes and mitochondrial variations. This subtype localized close to synaptic structures in the OPL. The other subtype appeared as pale phagocytic microglia localized among degenerating outer segments. The Iba1-and CD11b-immunoreactive microglia in degenerating retina may be of two separate subtypes, which differ in localization, subcellular morphology and perhaps function.
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Affiliation(s)
| | | | - Camilla Mohlin
- Department of Chemistry and Biomedicine, Linnaeus University, Kalmar, Sweden
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Chang LYL, Ardiles AO, Tapia-Rojas C, Araya J, Inestrosa NC, Palacios AG, Acosta ML. Evidence of Synaptic and Neurochemical Remodeling in the Retina of Aging Degus. Front Neurosci 2020; 14:161. [PMID: 32256305 PMCID: PMC7095275 DOI: 10.3389/fnins.2020.00161] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/11/2020] [Indexed: 02/06/2023] Open
Abstract
Accumulation of amyloid-beta (Aβ) peptides is regarded as the hallmark of neurodegenerative alterations in the brain of Alzheimer’s disease (AD) patients. In the eye, accumulation of Aβ peptides has also been suggested to be a trigger of retinal neurodegenerative mechanisms. Some pathological aspects associated with Aβ levels in the brain are synaptic dysfunction, neurochemical remodeling and glial activation, but these changes have not been established in the retina of animals with Aβ accumulation. We have employed the Octodon degus in which Aβ peptides accumulated in the brain and retina as a function of age. This current study investigated microglial morphology, expression of PSD95, synaptophysin, Iba-1 and choline acetyltransferase (ChAT) in the retina of juvenile, young and adult degus using immunolabeling methods. Neurotransmitters glutamate and gamma-aminobutyric acid (GABA) were detected using immunogold labeling and glutamate receptor subunits were quantified using Western blotting. There was an age-related increase in presynaptic and a decrease in post-synaptic retinal proteins in the retinal plexiform layers. Immunolabeling showed changes in microglial morphology characteristic of intermediate stages of activation around the optic nerve head (ONH) and decreasing activation toward the peripheral retina. Neurotransmitter expression pattern changed at juvenile ages but was similar in adults. Collectively, the results suggest that microglial activation, synaptic remodeling and neurotransmitter changes may be consequent to, or parallel to Aβ peptide and phosphorylated tau accumulation in the retina.
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Affiliation(s)
- Lily Y-L Chang
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Alvaro O Ardiles
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Cheril Tapia-Rojas
- Department of Cell and Molecular Biology, Faculty of Biological Sciences, Center for Aging and Regeneration, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Joaquin Araya
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Nibaldo C Inestrosa
- Department of Cell and Molecular Biology, Faculty of Biological Sciences, Center for Aging and Regeneration, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Adrian G Palacios
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Monica L Acosta
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.,New Zealand National Eye Centre, The University of Auckland, Auckland, New Zealand.,Faculty of Medical and Health Sciences, Centre for Brain Research, The University of Auckland, Auckland, New Zealand.,Brain Research New Zealand - Rangahau Roro Aotearoa, Auckland, New Zealand
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27
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Appelbaum T, Santana E, Aguirre GD. Critical Decrease in the Level of Axon Guidance Receptor ROBO1 in Rod Synaptic Terminals Is Followed by Axon Retraction. Invest Ophthalmol Vis Sci 2020; 61:11. [PMID: 32176262 PMCID: PMC7405958 DOI: 10.1167/iovs.61.3.11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/14/2019] [Indexed: 12/24/2022] Open
Abstract
Purpose To define remodeling of photoreceptor synaptic terminals and second-order retinal neurons in canine X-linked progressive retinal atrophy 1 caused by a five-nucleotide deletion in the RPGR exon ORF15. Methods Retinas of normal and mutant dogs were used for gene expression, Western blot, and immunohistochemistry. Cell-specific markers were used to examine disease-dependent retinal remodeling. Results In mutant retinas, a number of rod axon terminals retract into the outer nuclear layer. This neuritic atrophy preceded significant loss of rods and was evident early in disease. Rod bipolar and horizontal cell processes were found to extend into the outer nuclear layer, where they seemed to form contacts with the spherules of rod photoreceptors. No ectopic rewiring was observed. Because cytoskeletal reorganization was previously shown to underlie photoreceptor axon retraction, we examined normal and mutant retinas for expression of axon guidance receptors ROBO1 and ROBO2, which are known to regulate actin cytoskeleton dynamics. We found that the overall expression of both ROBO1 and ROBO2 is retained at the same level in premature and fully developed normal retinas. However, analysis of predisease and early disease retinas identified markedly decreased levels of ROBO1 in rod spherules compared with controls. In contrast, no differences in ROBO1 signals were noted in cone pedicles in normal and mutant retinas, where ROBO1 levels remained similarly low. Conclusions Depletion of ROBO1 in rod synaptic terminals correlates with the remodeling of axonal and dendritic processes in the outer retina of dogs with X-linked progressive retinal atrophy 1 and may play a role in the retraction of rod axons.
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Affiliation(s)
- Tatyana Appelbaum
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Evelyn Santana
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Gustavo D. Aguirre
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
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28
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Fan Y, Lai J, Yuan Y, Wang L, Wang Q, Yuan F. Taurine Protects Retinal Cells and Improves Synaptic Connections in Early Diabetic Rats. Curr Eye Res 2020; 45:52-63. [PMID: 31404506 DOI: 10.1080/02713683.2019.1653927] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/02/2019] [Accepted: 08/05/2019] [Indexed: 12/20/2022]
Abstract
Purpose: Taurine has long been thought to be involved in retinal protection from retinal degenerative diseases, but the underlying molecular mechanisms remain unclear. Retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy (DR) that precedes and participates in the microcirculatory abnormalities that occur in DR. Our objective was to investigate the role and mechanisms of taurine in early diabetic retinas.Methods: Eight-week-old STZ-induced diabetic rats and control animals were randomly assigned to receive taurine or vehicle by intraperitoneal injection or by intragastric administration. The retinal function and retinal cell counts were evaluated using an electroretinography (ERG) and immunofluorescence microscopy. Plasma amino acids were measured by ion-exchange chromatography (IEC). The expression levels of retinal taurine transporter (Tau-T), mitochondria-dependent apoptosis-associated genes and reactive gliosis markers were studied by western blotting and immunofluorescence. Pre- and post-synaptic markers (PSD95 and mGluR6) in outer plexiform layer (OPL), and the bipolar cell marker protein kinase C alpha (PKCα) were localized by immunofluorescence. Levels of PSD95 and mGluR6 were determined by quantitative western blot.Results: Taurine significantly prevented the reduction of photopic b-wave amplitude and retinal cone cells and ganglion cells loss and maintained the Bcl-2/Bax ratio balance in diabetic rats. Taurine also prevented the upregulation of glial fibrillary acidic protein (GFAP) and reduced retinal reactive gliosis. Taurine reduced plasma glutamate and tyrosine levels, which were elevated in diabetic rats. Moreover, mGluR6 levels reduction detected by western blot and immunofluorescence in diabetic retinas was inhibited and the displacement of mGluR6 in OPL into the inner nuclear layer (INL) detected by immunofluorescence was reduced by Taurine treatment.Conclusion: Taurine may protect retinal cells from diabetic attacks by activating Tau-T, reducing retinal reactive gliosis, improving retinal synaptic connections and decreasing retinal cell apoptosis. Thus, taurine treatment may be a novel approach for early DR.
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Affiliation(s)
- Yichao Fan
- Department of Ophthalmology, Zhongshan Hospital Affiliated to Fudan University, Shanghai, China
| | - Jie Lai
- Department of Ophthalmology, First Affiliated Hospital of Nanchang University Nanchang, Jiangxi, China
| | - Yuanzhi Yuan
- Department of Ophthalmology, Zhongshan Hospital Affiliated to Fudan University, Shanghai, China
| | - Liyang Wang
- Department of Ophthalmology, Zhongshan Hospital Affiliated to Fudan University, Shanghai, China
| | - Qingping Wang
- Department of Ophthalmology, Huashan Hospital Affiliated to Fudan University, Shanghai, China
| | - Fei Yuan
- Department of Ophthalmology, Zhongshan Hospital Affiliated to Fudan University, Shanghai, China
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Ivanova E, Kovacs-Oller T, Sagdullaev BT. Domain-specific distribution of gap junctions defines cellular coupling to establish a vascular relay in the retina. J Comp Neurol 2019; 527:2675-2693. [PMID: 30950036 PMCID: PMC6721971 DOI: 10.1002/cne.24699] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/02/2019] [Accepted: 04/02/2019] [Indexed: 12/22/2022]
Abstract
In the retina, diverse functions of neuronal gap junctions (GJs) have been established. However, the distribution and function of vascular GJs are less clear. Here in the mouse retina whole mounts, we combined structural immunohistochemical analysis and a functional assessment of cellular coupling with a GJ-permeable tracer Neurobiotin to determine distribution patterns of three major vascular connexins. We found that Cx43 was expressed in punctate fashion on astroglia, surrounding all types of blood vessels and in continuous string-like structures along endothelial cell contacts in specialized regions of the vascular tree. Specifically, these Cx43-positive strings originated at the finest capillaries and extended toward the feeding artery. As this structural arrangement promoted strong and exclusive coupling of pericytes and endothelial cells along the corresponding branch, we termed this region a "vascular relay." Cx40 expression was found predominantly along the endothelial cell contacts of the primary arteries and did not overlap with Cx43-positive strings. At their occupied territories, Cx43 and Cx40 clustered with tight junctions and, to a lesser extent, with adhesion contacts, both key elements of the blood-retina barrier. Finally, Cx37 puncta were associated with the entire surface of both mural and endothelial cells across all regions of the vascular tree. This combinatorial analysis of vascular connexins and identification of the vascular relay region will serve as a structural foundation for future studies of neurovascular signaling in health and disease.
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Affiliation(s)
- Elena Ivanova
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, New York
| | - Tamas Kovacs-Oller
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, New York
| | - Botir T Sagdullaev
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, New York
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Zhang X, Zhu J, Chen X, Jie-Qiong Z, Li X, Luo L, Huang H, Liu W, Zhou X, Yan J, Lin S, Ye J. Interferon Regulatory Factor 3 Deficiency Induces Age-Related Alterations of the Retina in Young and Old Mice. Front Cell Neurosci 2019; 13:272. [PMID: 31281243 PMCID: PMC6596281 DOI: 10.3389/fncel.2019.00272] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 06/05/2019] [Indexed: 12/20/2022] Open
Abstract
Age-related changes in visual function and retina structure are very common in aged animals, but the underlying mechanisms of these changes remain unclear. Here we report that the expression of interferon regulatory factor 3 (IRF3), a critical immune regulatory factor, is dramatically down-regulated in mouse retinas during aging. To address the role of IRF3 in the retina, we examined the structure and function of retinas in young (3–4 months) and old (22–24 months) Irf3-/- mice in comparison to age-matched wildtype (WT) mice. We found that IRF3 deletion resulted in impaired electroretinogram (ERG) responses and decreased retinal thickness in both young and old mice. In addition, numerous synapses of the outer plexiform layer (OPL) were found obviously extending into outer nuclear layer (ONL) in Irf3-/- mice, along with a reduction of the average synapse density in the OPL. These changes suggest that IRF3 deletion may accelerate retinal senescence. In support of this hypothesis, a number of classic senescence-associated markers were found in remarkably elevated level in Irf3-/- retina, including p53, p16INK4a, inositol-requiring enzyme 1α (IREα), p-H2A.X and promyelocytic leukemia protein (PML). Overall, our results indicate that maintenance normal IRF3 levels is necessary for retinal structure and function and suggest that IRF3 is an important regulator of retinal senescence.
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Affiliation(s)
- Xi Zhang
- Department of Ophthalmology, Institute of Surgery Research, Army Medical Center of PLA (Daping Hospital), Army Medical University, Chongqing, China
| | - Jingyi Zhu
- Department of Ophthalmology, Institute of Surgery Research, Army Medical Center of PLA (Daping Hospital), Army Medical University, Chongqing, China
| | - Xianjun Chen
- Department of Histology and Embryology, Chongqing Key Laboratory of Neurobiology, Army Medical University, Chongqing, China
| | - Zhang Jie-Qiong
- Department of Ophthalmology, Institute of Surgery Research, Army Medical Center of PLA (Daping Hospital), Army Medical University, Chongqing, China
| | - Xue Li
- Department of Ophthalmology, Institute of Surgery Research, Army Medical Center of PLA (Daping Hospital), Army Medical University, Chongqing, China
| | - Linlin Luo
- Department of Ophthalmology, Institute of Surgery Research, Army Medical Center of PLA (Daping Hospital), Army Medical University, Chongqing, China
| | - Huang Huang
- Institute of Immunology, Army Medical University, Chongqing, China
| | - Wenyi Liu
- Department of Ophthalmology, Institute of Surgery Research, Army Medical Center of PLA (Daping Hospital), Army Medical University, Chongqing, China
| | - Xinyuan Zhou
- Institute of Immunology, Army Medical University, Chongqing, China
| | - Jun Yan
- Department of Ophthalmology, Institute of Surgery Research, Army Medical Center of PLA (Daping Hospital), Army Medical University, Chongqing, China
| | - Sen Lin
- Department of Ophthalmology, Institute of Surgery Research, Army Medical Center of PLA (Daping Hospital), Army Medical University, Chongqing, China
| | - Jian Ye
- Department of Ophthalmology, Institute of Surgery Research, Army Medical Center of PLA (Daping Hospital), Army Medical University, Chongqing, China
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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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Zhang X, Piano I, Messina A, D'Antongiovanni V, Crò F, Provenzano G, Bozzi Y, Gargini C, Casarosa S. Retinal defects in mice lacking the autism-associated gene Engrailed-2. Neuroscience 2019; 408:177-190. [DOI: 10.1016/j.neuroscience.2019.03.061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 03/26/2019] [Accepted: 03/31/2019] [Indexed: 10/27/2022]
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Okawa H, Yu WQ, Matti U, Schwarz K, Odermatt B, Zhong H, Tsukamoto Y, Lagnado L, Rieke F, Schmitz F, Wong ROL. Dynamic assembly of ribbon synapses and circuit maintenance in a vertebrate sensory system. Nat Commun 2019; 10:2167. [PMID: 31092821 PMCID: PMC6520400 DOI: 10.1038/s41467-019-10123-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 04/10/2019] [Indexed: 11/11/2022] Open
Abstract
Ribbon synapses transmit information in sensory systems, but their development is not well understood. To test the hypothesis that ribbon assembly stabilizes nascent synapses, we performed simultaneous time-lapse imaging of fluorescently-tagged ribbons in retinal cone bipolar cells (BCs) and postsynaptic densities (PSD95-FP) of retinal ganglion cells (RGCs). Ribbons and PSD95-FP clusters were more stable when these components colocalized at synapses. However, synapse density on ON-alpha RGCs was unchanged in mice lacking ribbons (ribeye knockout). Wildtype BCs make both ribbon-containing and ribbon-free synapses with these GCs even at maturity. Ribbon assembly and cone BC-RGC synapse maintenance are thus regulated independently. Despite the absence of synaptic ribbons, RGCs continued to respond robustly to light stimuli, although quantitative examination of the responses revealed reduced frequency and contrast sensitivity.
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Affiliation(s)
- Haruhisa Okawa
- Department of Biological Structure, University of Washington, Seattle, 98195, WA, USA
| | - Wan-Qing Yu
- Department of Biological Structure, University of Washington, Seattle, 98195, WA, USA
| | - Ulf Matti
- Department of Neuroanatomy, Medical School Homburg/Saar, Institute for Anatomy and Cell Biology, Saarland University, Homburg/Saar, 66421, Germany
| | - Karin Schwarz
- Department of Neuroanatomy, Medical School Homburg/Saar, Institute for Anatomy and Cell Biology, Saarland University, Homburg/Saar, 66421, Germany
| | | | - Haining Zhong
- Vollum institute, Oregon Health and Science University, Portland, 97239, OR, USA
| | - Yoshihiko Tsukamoto
- Department of Biology, Hyogo College of Medicine, Nishinomiya, 663-8501, Hyogo, Japan
| | - Leon Lagnado
- School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, 98195, WA, USA
| | - Frank Schmitz
- Department of Neuroanatomy, Medical School Homburg/Saar, Institute for Anatomy and Cell Biology, Saarland University, Homburg/Saar, 66421, Germany
| | - Rachel O L Wong
- Department of Biological Structure, University of Washington, Seattle, 98195, WA, USA.
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Uppal S, Liu T, Poliakov E, Gentleman S, Redmond TM. The dual roles of RPE65 S-palmitoylation in membrane association and visual cycle function. Sci Rep 2019; 9:5218. [PMID: 30914787 PMCID: PMC6435699 DOI: 10.1038/s41598-019-41501-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 03/07/2019] [Indexed: 12/31/2022] Open
Abstract
Association with the endoplasmic reticulum (ER) membrane is a critical requirement for the catalytic function of RPE65. Several studies have investigated the nature of the RPE65-membrane interaction; however, complete understanding of its mode of membrane binding is still lacking. Previous biochemical studies suggest the membrane interaction can be partly attributed to S-palmitoylation, but the existence of RPE65 palmitoylation remains a matter of debate. Here, we re-examined RPE65 palmitoylation, and its functional consequence in the visual cycle. We clearly demonstrate that RPE65 is post-translationally modified by a palmitoyl moiety, but this is not universal (about 25% of RPE65). By extensive mutational studies we mapped the S-palmitoylation sites to residues C112 and C146. Inhibition of palmitoylation using 2-bromopalmitate and 2-fluoropalmitate completely abolish its membrane association. Furthermore, palmitoylation-deficient C112 mutants are significantly impeded in membrane association. Finally, we show that RPE65 palmitoylation level is highly regulated by lecithin:retinol acyltransferase (LRAT) enzyme. In the presence of all-trans retinol, LRAT substrate, there is a significant decrease in the level of palmitoylation of RPE65. In conclusion, our findings suggest that RPE65 is indeed a dynamically-regulated palmitoylated protein and that palmitoylation is necessary for regulating its membrane binding, and to perform its normal visual cycle function.
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Affiliation(s)
- Sheetal Uppal
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Tingting Liu
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, United States.,Department of Transfusion, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, P.R. China
| | - Eugenia Poliakov
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Susan Gentleman
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - T Michael Redmond
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, United States.
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35
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Yang Y, Liu W, Sun K, Jiang L, Zhu X. Tmem30a deficiency leads to retinal rod bipolar cell degeneration. J Neurochem 2019; 148:400-412. [PMID: 30548540 DOI: 10.1111/jnc.14643] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 11/09/2018] [Accepted: 12/02/2018] [Indexed: 12/13/2022]
Abstract
Phospholipids are asymmetrically distributed across the mammalian plasma membrane, with phosphatidylserine (PS) and phosphatidylethanolamine concentrated in the cytoplasmic leaflet of the membrane bilayer and phosphatidylcholine in the exoplasmic leaflet. This asymmetric distribution is dependent on a group of P4 ATPases called PS flippases. The proper transport and function of PS flippases require a β-subunit transmembrane protein 30A (TMEM30A). Disruption of PS flippases leads to several human diseases. Tmem30a is essential for photoreceptor survival. However, the roles of Tmem30a in the retinal rod bipolar cells (RBC) remain elusive. To investigate the role of Tmem30a in the RBCs, we generated a RBC-specific Tmem30a knockout (cKO) mouse model using PCP2-Cre line. The Tmem30a cKO mice exhibited defect in RBC function and progressive RBC death. PKCα staining of retinal cryosections from cKO mice revealed a remarkable dendritic sprouting of rod bipolar cells during the early degenerative process. Immunostaining analysis of PSD95 and mGluT6 expression demonstrated that rod bipolar cells in Tmem30a cKO retinas exhibited aberrant dendritic sprouting as a result of impaired synaptic efficacy, which implied a crucial role for Tmem30a in synaptic transmission in the retina. In addition, loss of Tmem30a led to reactive gliosis with increased expression of glial fibrillary acidic protein and CD68. TUNEL staining suggested that apoptotic cell death occurred in the retinal inner nuclear layer (INL). Our data show that loss of Tmem30a in RBCs results in dendritic sprouting of rod bipolar cells, increased astrogliosis and RBC death. Taken together, our studies demonstrate an essential role for Tmem30a in the retinal bipolar cells. Cover Image for this issue: doi: 10.1111/jnc.14492.
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Affiliation(s)
- Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Wenjing Liu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Kuanxiang Sun
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Li Jiang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, China
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China.,Department of Ophthalmology, Shangqiu First Municipal People's Hospital, Shangqiu, Henan, China.,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, China.,Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, China
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36
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Molday LL, Cheng CL, Molday RS. Cell-Specific Markers for the Identification of Retinal Cells and Subcellular Organelles by Immunofluorescence Microscopy. Methods Mol Biol 2019; 1834:293-310. [PMID: 30324451 DOI: 10.1007/978-1-4939-8669-9_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Identification of specific cells and subcellular structures in the retina is fundamental for understanding the visual process, retinal development, disease progression, and therapeutic intervention. The increased use of knockout, transgenic, and naturally occurring mutant mice has further underlined the need for retinal cell-specific imaging. Immunofluorescence microscopy of retinal cryosections and whole-mount tissue labeled with cell-specific markers has emerged as the method of choice for identifying and quantifying specific cell populations and mapping their distribution within the retina. Immunofluorescence microscopy has also been important in localizing proteins to specific compartments of retinal cells. In most cases indirect labeling methods are employed in which lightly fixed retinal samples are first labeled with a primary antibody targeted against a cell-specific protein of interest and then labeled with a fluorescent dye-tagged secondary antibody that recognizes the primary antibody. The localization and relative abundance of the protein can be readily imaged under a conventional fluorescent or confocal scanning microscope. Immunofluorescence labeling can be adapted for imaging more than one antigen through the use of multiple antibodies and different, non-overlapping fluorescent dyes. A number of well-characterized immunochemical markers are now available for detecting photoreceptors, bipolar cells, amacrine cells, horizontal cells, Müller cells, and retinal pigment epithelial cells in the retina of mice and other mammals. Immunochemical markers are also available for visualizing the distribution of specific proteins within cells with most studies directed toward photoreceptor cells.
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Affiliation(s)
- Laurie L Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Christiana L Cheng
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
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37
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Pang JJ, Yang Z, Jacoby RA, Wu SM. Cone synapses in mammalian retinal rod bipolar cells. J Comp Neurol 2018; 526:1896-1909. [PMID: 29667170 PMCID: PMC6031453 DOI: 10.1002/cne.24456] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 11/29/2017] [Accepted: 11/30/2017] [Indexed: 01/25/2023]
Abstract
Some mammalian rod bipolar cells (RBCs) can receive excitatory chemical synaptic inputs from both rods and cones (DBCR2 ), but anatomical evidence for mammalian cone-RBC contacts has been sparse. We examined anatomical cone-RBC contacts using neurobiotin (NB) to visualize individual mouse cones and standard immuno-markers to identify RBCs, cone pedicles and synapses in mouse and baboon retinas. Peanut agglutinin (PNA) stained the basal membrane of all cone pedicles, and mouse cones were positive for red/green (R/G)-opsin, whereas baboon cones were positive for calbindin D-28k. All synapses in the outer plexiform layer were labeled for synaptic vesicle protein 2 (SV2) and PSD (postsynaptic density)-95, and those that coincided with PNA resided closest to bipolar cell somas. Cone-RBC synaptic contacts were identified by: (a) RBC dendrites deeply invaginating into the center of cone pedicles (invaginating synapses), (b) RBC dendritic spines intruding into the surface of cone pedicles (superficial synapses), and (c) PKCα immunoreactivity coinciding with synaptic marker SV2, PSD-95, mGluR6, G protein beta 5 or PNA at cone pedicles. One RBC could form 0-1 invaginating and 1-3 superficial contacts with cones. 20.7% and 38.9% of mouse RBCs contacted cones in the peripheral and central retina (p < .05, n = 14 samples), respectively, while 34.4% (peripheral) and 48.5% (central) of cones contacted RBCs (p > .05). In baboon retinas (n = 4 samples), cone-RBC contacts involved 12.2% of RBCs (n = 416 cells) and 22.5% of cones (n = 225 cells). This suggests that rod and cone signals in the ON pathway are integrated in some RBCs before reaching AII amacrine cells.
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Affiliation(s)
- Ji-Jie Pang
- Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, 77030
| | - Zhuo Yang
- Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, 77030
| | - Roy A Jacoby
- Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, 77030
| | - Samuel M Wu
- Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, 77030
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Abstract
The transient receptor potential channel TRPM1 is required for synaptic transmission between photoreceptors and the ON subtype of bipolar cells (ON-BPC), mediating depolarization in response to light. TRPM1 is present in the somas and postsynaptic dendritic tips of ON-BPCs. Monoclonal antibodies generated against full-length TRPM1 were found to have differential labeling patterns when used to immunostain the mouse retina, with some yielding reduced labeling of dendritic tips relative to the labeling of cell bodies. Epitope mapping revealed that those antibodies that poorly label the dendritic tips share a binding site (N2d) in the N-terminal arm near the transmembrane domain. A major splice variant of TRPM1 lacking exon 19 does not contain the N2d binding site, but quantitative immunoblotting revealed no enrichment of this variant in synaptsomes. One explanation of the differential labeling is masking of the N2d epitope by formation of a synapse-specific multiprotein complex. Identifying the binding partners that are specific for the fraction of TRPM1 present at the synapses is an ongoing challenge for understanding TRPM1 function.
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39
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Sarin S, Zuniga-Sanchez E, Kurmangaliyev YZ, Cousins H, Patel M, Hernandez J, Zhang KX, Samuel MA, Morey M, Sanes JR, Zipursky SL. Role for Wnt Signaling in Retinal Neuropil Development: Analysis via RNA-Seq and In Vivo Somatic CRISPR Mutagenesis. Neuron 2018; 98:109-126.e8. [PMID: 29576390 DOI: 10.1016/j.neuron.2018.03.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 01/16/2018] [Accepted: 03/02/2018] [Indexed: 12/22/2022]
Abstract
Screens for genes that orchestrate neural circuit formation in mammals have been hindered by practical constraints of germline mutagenesis. To overcome these limitations, we combined RNA-seq with somatic CRISPR mutagenesis to study synapse development in the mouse retina. Here synapses occur between cellular layers, forming two multilayered neuropils. The outer neuropil, the outer plexiform layer (OPL), contains synapses made by rod and cone photoreceptor axons on rod and cone bipolar dendrites, respectively. We used RNA-seq to identify selectively expressed genes encoding cell surface and secreted proteins and CRISPR-Cas9 electroporation with cell-specific promoters to assess their roles in OPL development. Among the genes identified in this way are Wnt5a and Wnt5b. They are produced by rod bipolars and activate a non-canonical signaling pathway in rods to regulate early OPL patterning. The approach we use here can be applied to other parts of the brain.
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Affiliation(s)
- Sumeet Sarin
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA
| | - Elizabeth Zuniga-Sanchez
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yerbol Z Kurmangaliyev
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Henry Cousins
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA
| | - Mili Patel
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA
| | - Jeanette Hernandez
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kelvin X Zhang
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Melanie A Samuel
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA
| | - Marta Morey
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Joshua R Sanes
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02130, USA.
| | - S Lawrence Zipursky
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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40
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Tetenborg S, Yadav SC, Hormuzdi SG, Monyer H, Janssen-Bienhold U, Dedek K. Differential Distribution of Retinal Ca 2+/Calmodulin-Dependent Kinase II (CaMKII) Isoforms Indicates CaMKII-β and -δ as Specific Elements of Electrical Synapses Made of Connexin36 (Cx36). Front Mol Neurosci 2017; 10:425. [PMID: 29311815 PMCID: PMC5742114 DOI: 10.3389/fnmol.2017.00425] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 12/05/2017] [Indexed: 12/17/2022] Open
Abstract
AII amacrine cells are essential interneurons of the primary rod pathway and transmit rod-driven signals to ON cone bipolar cells to enable scotopic vision. Gap junctions made of connexin36 (Cx36) mediate electrical coupling among AII cells and between AII cells and ON cone bipolar cells. These gap junctions underlie a remarkable degree of plasticity and are modulated by different signaling cascades. In particular, Ca2+/calmodulin-dependent protein kinase II (CaMKII) has been characterized as an important regulator of Cx36, capable of potentiating electrical coupling in AII cells. However, it is unclear which CaMKII isoform mediates this effect. To obtain a more detailed understanding of the isoform composition of CaMKII at retinal gap junctions, we analyzed the retinal distribution of all four CaMKII isoforms using confocal microscopy. These experiments revealed a differential distribution of CaMKII isoforms: CaMKII-α was strongly expressed in starburst amacrine cells, which are known to lack electrical coupling. CaMKII-β was abundant in OFF bipolar cells, which form electrical synapses in the outer and the inner retina. CaMKII-γ was diffusely distributed across the entire retina and could not be assigned to a specific cell type. CaMKII-δ labeling was evident in bipolar and AII amacrine cells, which contain the majority of Cx36-immunoreactive puncta in the inner retina. We double-labeled retinas for Cx36 and the four CaMKII isoforms and revealed that the composition of the CaMKII enzyme differs between gap junctions in the outer and the inner retina: in the outer retina, only CaMKII-β colocalized with Cx36-containing gap junctions, whereas in the inner retina, CaMKII-β and -δ colocalized with Cx36. This finding suggests that gap junctions in the inner and the outer retina may be regulated differently although they both contain the same connexin. Taken together, our study identifies CaMKII-β and -δ as Cx36-specific regulators in the mouse retina with CaMKII-δ regulating the primary rod pathway.
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Affiliation(s)
- Stephan Tetenborg
- Animal Navigation/Neurosensorics, Institute for Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany
| | - Shubhash C Yadav
- Animal Navigation/Neurosensorics, Institute for Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany
| | - Sheriar G Hormuzdi
- Division of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom
| | | | - Ulrike Janssen-Bienhold
- Visual Neuroscience, Department of Neuroscience, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Karin Dedek
- Animal Navigation/Neurosensorics, Institute for Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
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41
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Fujikawa A, Chow JPH, Matsumoto M, Suzuki R, Kuboyama K, Yamamoto N, Noda M. Identification of novel splicing variants of protein tyrosine phosphatase receptor type Z. J Biochem 2017; 162:381-390. [PMID: 28992190 DOI: 10.1093/jb/mvx042] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 06/14/2017] [Indexed: 11/13/2022] Open
Abstract
Protein tyrosine phosphatase receptor type Z (PTPRZ, also known as PTPζ or RPTPβ) is preferentially expressed in the central nervous system (CNS). PTPRZ plays important roles during development and adulthood in CNS myelination, learning and memory. Three splicing isoforms for PTPRZ have been identified to date: two receptor type isoforms, PTPRZ-A and PTPRZ-B, and one secretory isoform, PTPRZ-S. We herein identified novel PTPRZ receptor sub-isoforms without a seven-amino acid sequence encoded by exon 16. This sequence forms a part of the helix-turn-helix segment called the 'wedge' structure, which is located at the N-terminal region in the membrane-proximal protein tyrosine phosphatase domain. In contrast to conventional receptor isoforms with uniform expression, the deleted isoforms were expressed in the brain, but not in the retina, indicating the tissue-specific splicing of exon 16. Biochemical analyses of PTPRZ intracellular regions revealed differences in the characteristics of the deleted form, namely, stronger binding activity to postsynaptic density protein 95 (PSD95) and greater enrichment in the postsynaptic density fraction than the full-length form. Furthermore, the exon 16-deleted form exhibited higher catalytic efficiency in vitro. These results suggest that sub-isoforms of PTPRZ have different functions because of variations in the wedge structure.
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Affiliation(s)
- Akihiro Fujikawa
- Division of Molecular Neurobiology, National Institute for Basic Biology
| | - Jeremy Pak Hong Chow
- Division of Molecular Neurobiology, National Institute for Basic Biology.,School of Life Science, Graduate University for Advanced Studies, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi 444-8787, Japan
| | - Masahito Matsumoto
- Division of Molecular Neurobiology, National Institute for Basic Biology
| | - Ryoko Suzuki
- Division of Molecular Neurobiology, National Institute for Basic Biology
| | - Kazuya Kuboyama
- Division of Molecular Neurobiology, National Institute for Basic Biology
| | - Naoki Yamamoto
- Laboratory of Molecular Biology & Histochemistry, Fujita Health University, 1-98, Toyoake, Aichi 470-1192, Japan
| | - Masaharu Noda
- Division of Molecular Neurobiology, National Institute for Basic Biology.,School of Life Science, Graduate University for Advanced Studies, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi 444-8787, Japan
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42
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Hartveit E, Zandt BJ, Madsen E, Castilho Á, Mørkve SH, Veruki ML. AMPA receptors at ribbon synapses in the mammalian retina: kinetic models and molecular identity. Brain Struct Funct 2017; 223:769-804. [PMID: 28936725 DOI: 10.1007/s00429-017-1520-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 09/10/2017] [Indexed: 10/24/2022]
Abstract
In chemical synapses, neurotransmitter molecules released from presynaptic vesicles activate populations of postsynaptic receptors that vary in functional properties depending on their subunit composition. Differential expression and localization of specific receptor subunits are thought to play fundamental roles in signal processing, but our understanding of how that expression is adapted to the signal processing in individual synapses and microcircuits is limited. At ribbon synapses, glutamate release is independent of action potentials and characterized by a high and rapidly changing rate of release. Adequately translating such presynaptic signals into postsynaptic electrical signals poses a considerable challenge for the receptor channels in these synapses. Here, we investigated the functional properties of AMPA receptors of AII amacrine cells in rat retina that receive input at spatially segregated ribbon synapses from OFF-cone and rod bipolar cells. Using patch-clamp recording from outside-out patches, we measured the concentration dependence of response amplitude and steady-state desensitization, the single-channel conductance and the maximum open probability. The GluA4 subunit seems critical for the functional properties of AMPA receptors in AII amacrines and immunocytochemical labeling suggested that GluA4 is located at synapses made by both OFF-cone bipolar cells and rod bipolar cells. Finally, we used a series of experimental observables to develop kinetic models for AII amacrine AMPA receptors and subsequently used the models to explore the behavior of the receptors and responses generated by glutamate concentration profiles mimicking those occurring in synapses. These models will facilitate future in silico modeling of synaptic signaling and processing in AII amacrine cells.
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Affiliation(s)
- Espen Hartveit
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.
| | - Bas-Jan Zandt
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.,Blue Brain Project, École polytechnique fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Eirik Madsen
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.,Department of Radiology, Førde Central Hospital, Førde, Norway
| | - Áurea Castilho
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway
| | - Svein Harald Mørkve
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.,Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.,Department of Radiology, Haukeland University Hospital, Bergen, Norway
| | - Margaret Lin Veruki
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.
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43
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The nuclear hormone receptor gene Nr2c1 (Tr2) is a critical regulator of early retina cell patterning. Dev Biol 2017; 429:343-355. [DOI: 10.1016/j.ydbio.2017.05.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 05/17/2017] [Accepted: 05/19/2017] [Indexed: 02/08/2023]
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44
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Loss of Neuroligin3 specifically downregulates retinal GABAAα2 receptors without abolishing direction selectivity. PLoS One 2017; 12:e0181011. [PMID: 28708891 PMCID: PMC5510863 DOI: 10.1371/journal.pone.0181011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 06/23/2017] [Indexed: 11/19/2022] Open
Abstract
The postsynaptic adhesion proteins Neuroligins (NLs) are essential for proper synapse function, and their alterations are associated with a variety of neurodevelopmental disorders. It is increasingly clear that each NL isoform occupies specific subsets of synapses and is able to regulate the function of discrete networks. Studies of NL2 and NL4 in the retina in particular have contributed towards uncovering their role in inhibitory synapse function. In this study we show that NL3 is also predominantly expressed at inhibitory postsynapses in the retinal inner plexiform layer (IPL), where it colocalizes with both GABAA- and glycinergic receptor clusters in a 3:2 ratio. In the NL3 deletion-mutant (knockout or KO) mouse, we uncovered a dramatic reduction of the number of GABAAα2-subunit containing GABAA receptor clusters at the IPL. Retinal activity was thereafter assessed in KO and wild-type (WT) littermates by multi-electrode-array recordings of the output cells of retina, the retinal ganglion cells (RGCs). RGCs in the NL3 KO showed reduced spontaneous activity and an altered response to white noise stimulation. Moreover, upon application of light flashes, the proportion of cells firing at light offset (OFF RGCs) was significantly lower in the NL3 KO compared to WT littermates, whereas the relative number of cells firing at light onset (ON RGCs) increased. Interestingly, although GABAAα2-bearing receptors have been related to direction-selective circuits of the retina, features of direction selective-retinal ganglion cells recorded remained unperturbed in the NL3 KO. Together our data underscore the importance of NL3 for the integrity of specific GABAAergic retinal circuits and identifies NL3 as an important regulator of retinal activity.
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Bulloj A, Maminishkis A, Mizui M, Finnemann SC. Semaphorin4D-PlexinB1 Signaling Attenuates Photoreceptor Outer Segment Phagocytosis by Reducing Rac1 Activity of RPE Cells. Mol Neurobiol 2017. [PMID: 28624895 DOI: 10.1007/s12035-017-0649-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Semaphorins form a family of secreted and membrane-bound molecules that were identified originally as axonal guidance factors during neuronal development. Given their wide distribution in many including mature tissues, semaphorin 4D (sema4D) and its main functional receptor plexin B1 (plxnB1) are expected to fulfill additional functions that remain to be uncovered. A main characteristic of the plexin receptor family is its ability to reorganize the cytoskeleton. PlxnB1 specifically may directly interact with Rho family GTPases to regulate F-actin driven pathways in cells in culture. Diurnal clearance phagocytosis by the retinal pigment epithelium (RPE) of photoreceptor outer segment fragments (POS) is critical for photoreceptor function and longevity. In this process, rearrangement of RPE cytoskeletal F-actin via activation of the Rho family GTPase Rac1 is essential for POS internalization. Here, we show a novel role in POS phagocytosis by RPE cells in culture and in vivo for plexin B1 and its ligand sema4D. Exogenous sema4D abolishes POS internalization (but not binding) by differentiated RPE cells in culture by decreasing the GTP load of Rac1. In the rat eye, sema4D localizes to retinal photoreceptors, while PlxnB1 is expressed by neighboring RPE cells. At the peak of diurnal retinal phagocytosis after light onset, plxnB1 phosphorylation and sema4D levels are reduced in wild-type rat retina in situ but not in mutant RCS rat retina in which the RPE lacks phagocytic activity. Finally, increased POS phagosome content after light onset is observed in the RPE in situ of mice with either plxnB1 or sema4D gene deletion. Altogether, our results demonstrate a novel physiological function for sema4D/plxnB1 signaling in RPE phagocytosis serving as attenuating brake prior to light onset whose release enables the diurnal phagocytic burst.
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Affiliation(s)
- Ayelen Bulloj
- Department of Biological Sciences Center for Cancer, Genetic Diseases, and Gene Regulation, Fordham University, Larkin Hall, 441 East Fordham Road, Bronx, NY, 10458, USA
| | - Arvydas Maminishkis
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Masayuki Mizui
- Department of Nephrology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan
| | - Silvia C Finnemann
- Department of Biological Sciences Center for Cancer, Genetic Diseases, and Gene Regulation, Fordham University, Larkin Hall, 441 East Fordham Road, Bronx, NY, 10458, USA.
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Xu B, Sun A, He Y, Qian F, Liu L, Chen Y, Luo H. Running-induced memory enhancement correlates with the preservation of thin spines in the hippocampal area CA1 of old C57BL/6 mice. Neurobiol Aging 2017; 52:106-116. [DOI: 10.1016/j.neurobiolaging.2017.01.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/31/2016] [Accepted: 01/02/2017] [Indexed: 01/01/2023]
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Nasir-Ahmad S, Lee SCS, Martin PR, Grünert U. Melanopsin-expressing ganglion cells in human retina: Morphology, distribution, and synaptic connections. J Comp Neurol 2017; 527:312-327. [PMID: 28097654 DOI: 10.1002/cne.24176] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/09/2017] [Accepted: 01/10/2017] [Indexed: 11/05/2022]
Abstract
Melanopsin-expressing retinal ganglion cells are intrinsically photosensitive cells that are involved in non-image forming visual processes such as the pupillary light reflex and circadian entrainment but also contribute to visual perception. Here we used immunohistochemistry to study the morphology, density, distribution, and synaptic connectivity of melanopsin-expressing ganglion cells in four post mortem human donor retinas. Two types of melanopsin-expressing ganglion cells were distinguished based on their dendritic stratification near either the outer or the inner border of the inner plexiform layer. Outer stratifying cells make up on average 60% of the melanopsin-expressing cells. About half of the melanopsin-expressing cells (or 80% of the outer stratifying cells) have their soma displaced to the inner nuclear layer. Inner stratifying cells have their soma exclusively in the ganglion cell layer and include a small proportion of bistratified cells. The dendritic field diameter of melanopsin-expressing cells ranges from 250 (near the fovea) to 1,000 µm in peripheral retina. The dendritic trees of outer stratifying cells cover the retina independent of soma location. The dendritic fields of both outer and inner stratifying cells show a high degree of overlap with a coverage factor of approximately two. Melanopsin-expressing cells occur at an average peak density of between ∼20 and ∼40 cells/mm2 at about 2 mm eccentricity, the density drops to below ∼10 cells/mm2 at about 8 mm eccentricity. Both the outer and inner stratifying dendrites express postsynaptic density (PSD95) immunoreactive puncta suggesting that they receive synaptic input from bipolar cells.
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Affiliation(s)
- Subha Nasir-Ahmad
- Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, 2000, Australia
| | - Sammy C S Lee
- Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, 2000, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, New South Wales, 2000, Australia
| | - Paul R Martin
- Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, 2000, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, New South Wales, 2000, Australia.,School of Medical Sciences, The University of Sydney, Sydney, New South Wales, 2000, Australia
| | - Ulrike Grünert
- Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, 2000, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, New South Wales, 2000, Australia.,School of Medical Sciences, The University of Sydney, Sydney, New South Wales, 2000, Australia
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Fasoli A, Dang J, Johnson JS, Gouw AH, Fogli Iseppe A, Ishida AT. Somatic and neuritic spines on tyrosine hydroxylase-immunopositive cells of rat retina. J Comp Neurol 2017; 525:1707-1730. [PMID: 28035673 DOI: 10.1002/cne.24166] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 12/13/2016] [Accepted: 12/27/2016] [Indexed: 12/27/2022]
Abstract
Dopamine- and tyrosine hydroxylase-immunopositive cells (TH cells) modulate visually driven signals as they flow through retinal photoreceptor, bipolar, and ganglion cells. Previous studies suggested that TH cells release dopamine from varicose axons arborizing in the inner and outer plexiform layers after glutamatergic synapses depolarize TH cell dendrites in the inner plexiform layer and these depolarizations propagate to the varicosities. Although it has been proposed that these excitatory synapses are formed onto appendages resembling dendritic spines, spines have not been found on TH cells of most species examined to date or on TH cell somata that release dopamine when exposed to glutamate receptor agonists. By use of protocols that preserve proximal retinal neuron morphology, we have examined the shape, distribution, and synapse-related immunoreactivity of adult rat TH cells. We report here that TH cell somata, tapering and varicose inner plexiform layer neurites, and varicose outer plexiform layer neurites all bear spines, that some of these spines are immunopositive for glutamate receptor and postsynaptic density proteins (viz., GluR1, GluR4, NR1, PSD-95, and PSD-93), that TH cell somata and tapering neurites are also immunopositive for a γ-aminobutyric acid (GABA) receptor subunit (GABAA Rα1 ), and that a synaptic ribbon-specific protein (RIBEYE) is found adjacent to some colocalizations of GluR1 and TH in the inner plexiform layer. These results identify previously undescribed sites at which glutamatergic and GABAergic inputs may stimulate and inhibit dopamine release, especially at somata and along varicose neurites that emerge from these somata and arborize in various levels of the retina. J. Comp. Neurol. 525:1707-1730, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Anna Fasoli
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - James Dang
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - Jeffrey S Johnson
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - Aaron H Gouw
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - Alex Fogli Iseppe
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - Andrew T Ishida
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California.,Department of Ophthalmology and Vision Science, University of California, Sacramento, California
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Sinha R, Hoon M, Baudin J, Okawa H, Wong ROL, Rieke F. Cellular and Circuit Mechanisms Shaping the Perceptual Properties of the Primate Fovea. Cell 2017; 168:413-426.e12. [PMID: 28129540 PMCID: PMC5298833 DOI: 10.1016/j.cell.2017.01.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/21/2016] [Accepted: 01/05/2017] [Indexed: 10/20/2022]
Abstract
The fovea is a specialized region of the retina that dominates the visual perception of primates by providing high chromatic and spatial acuity. While the foveal and peripheral retina share a similar core circuit architecture, they exhibit profound functional differences whose mechanisms are unknown. Using intracellular recordings and structure-function analyses, we examined the cellular and synaptic underpinnings of the primate fovea. Compared to peripheral vision, the fovea displays decreased sensitivity to rapid variations in light inputs; this difference is reflected in the responses of ganglion cells, the output cells of the retina. Surprisingly, and unlike in the periphery, synaptic inhibition minimally shaped the responses of foveal midget ganglion cells. This difference in inhibition cannot however, explain the differences in the temporal sensitivity of foveal and peripheral midget ganglion cells. Instead, foveal cone photoreceptors themselves exhibited slower light responses than peripheral cones, unexpectedly linking cone signals to perceptual sensitivity.
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Affiliation(s)
- Raunak Sinha
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA.
| | - Mrinalini Hoon
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, USA.
| | - Jacob Baudin
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
| | - Haruhisa Okawa
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, USA
| | - Rachel O L Wong
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, USA
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA.
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50
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Song L, Yu A, Murray K, Cortopassi G. Bipolar cell reduction precedes retinal ganglion neuron loss in a complex 1 knockout mouse model. Brain Res 2016; 1657:232-244. [PMID: 28027875 DOI: 10.1016/j.brainres.2016.12.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 01/03/2023]
Abstract
Inherited mitochondrial complex 1 deficiency causes Leber's hereditary Optic Neuropathy (LHON) and retinal ganglion cell (RGC) degeneration, and optic neuropathies are common in many inherited mitochondrial diseases. How mitochondrial defects pathomechanistically trigger optic neuropathy remains unclear. We observe that complex 1-deficient Ndufs4-/- mice present with acute vision loss around p30, and this vision loss is coincident with an 'inflammatory wave'. In order to understand what causes the inflammatory wave we explored retinal pathology that occurs from p20-p30. The results indicated that in the period p20-p30 in Ndufs4-/- retinas, there is: significant reduction in bipolar cells, RGC dendritic atrophy, reduced PSD95, increased oxidative stress as manifested by increased 4HNE, HO1 and Cuzn-SOD, increased mitochondrial biogenesis and increased apoptosis. These precede the major induction of 'inflammatory wave' at p30 shown previously, but occur earlier than frank RGC loss at p42. In general, complex 1 deficiency in retina triggers oxidative stress and mitochondrial respiratory dysfunction that causes death of the most sensitive cells, including bipolar cells and their synaptic contacts and amacrine cells in the early period, 20-24days. The early death of these cells is the likely precursor to the sharp rise in inflammatory molecules that occurs at day 30 and coincides with vision loss, and greatly precedes the death of RGCs that occurs at p42. These data suggest that metabolic antioxidant support of the most sensitive cells in the retina, or anti-inflammatory suppression of the consequences of their death, are both rational strategies for mitochondrial blinding disease.
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Affiliation(s)
- Lanying Song
- Vet Med: Molecular Biosciences, University of California, Davis, Davis, CA 95616, United States
| | - Alfred Yu
- Vet Med: Molecular Biosciences, University of California, Davis, Davis, CA 95616, United States
| | - Karl Murray
- Center for Neuroscience, University of California, Davis, Davis, CA 95616, United States; Department of Psychiatry & Behavioral Sciences, University of California, Davis, Davis, CA 95616, United States
| | - Gino Cortopassi
- Vet Med: Molecular Biosciences, University of California, Davis, Davis, CA 95616, United States.
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