1
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Cheung HW, Schouw AD, Altunay ZM, Maddox JW, Kresic LC, McAllister BC, Caro K, Alam S, Huang A, Pijewski RS, Lee A, Martinelli DC. Creation of a novel CRISPR-generated allele to express HA epitope-tagged C1QL1 and improved methods for its detection at synapses. FEBS Lett 2024. [PMID: 38858133 DOI: 10.1002/1873-3468.14946] [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: 02/05/2024] [Revised: 05/17/2024] [Accepted: 05/25/2024] [Indexed: 06/12/2024]
Abstract
C1QL1 is expressed in a subset of cells in the brain and likely has pleiotropic functions, including the regulation of neuron-to-neuron synapses. Research progress on C1QL proteins has been slowed by a dearth of available antibodies. Therefore, we created a novel knock-in mouse line in which an HA-tag is inserted into the endogenous C1ql1 locus. We examined the entire brain, identifying previously unappreciated nuclei expressing C1QL1, presumably in neurons. By total numbers, however, the large majority of C1QL1-expressing cells are of the oligodendrocyte lineage. Subcellular immunolocalization of synaptic cleft proteins is challenging, so we developed a new protocol to improve signal at synapses. Lastly, we compared various anti-HA antibodies to assist future investigations using this and likely other HA epitope-tagged alleles.
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Affiliation(s)
- Hiu W Cheung
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Alexander D Schouw
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Zeynep M Altunay
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - J Wesley Maddox
- Department of Neuroscience, University of Texas-Austin, TX, USA
| | - Lyndsay C Kresic
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Brenna C McAllister
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Keaven Caro
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Shahnawaz Alam
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Angie Huang
- Department of Neuroscience, University of Texas-Austin, TX, USA
| | - Robert S Pijewski
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
- Department of Biology, Anna Maria College, Paxton, MA, USA
| | - Amy Lee
- Department of Neuroscience, University of Texas-Austin, TX, USA
| | - David C Martinelli
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
- The Connecticut Institute for the Brain and Cognitive Sciences (IBACS), Storrs, CT, USA
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2
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Swygart D, Yu WQ, Takeuchi S, Wong ROL, Schwartz GW. A presynaptic source drives differing levels of surround suppression in two mouse retinal ganglion cell types. Nat Commun 2024; 15:599. [PMID: 38238324 PMCID: PMC10796971 DOI: 10.1038/s41467-024-44851-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 01/05/2024] [Indexed: 01/22/2024] Open
Abstract
In early sensory systems, cell-type diversity generally increases from the periphery into the brain, resulting in a greater heterogeneity of responses to the same stimuli. Surround suppression is a canonical visual computation that begins within the retina and is found at varying levels across retinal ganglion cell types. Our results show that heterogeneity in the level of surround suppression occurs subcellularly at bipolar cell synapses. Using single-cell electrophysiology and serial block-face scanning electron microscopy, we show that two retinal ganglion cell types exhibit very different levels of surround suppression even though they receive input from the same bipolar cell types. This divergence of the bipolar cell signal occurs through synapse-specific regulation by amacrine cells at the scale of tens of microns. These findings indicate that each synapse of a single bipolar cell can carry a unique visual signal, expanding the number of possible functional channels at the earliest stages of visual processing.
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Affiliation(s)
- David Swygart
- Northwestern University Interdepartmental Neuroscience Program, Chicago, IL, USA
| | - Wan-Qing Yu
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Shunsuke Takeuchi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Rachel O L Wong
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Gregory W Schwartz
- Northwestern University Interdepartmental Neuroscience Program, Chicago, IL, USA.
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Chicago, IL, USA.
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3
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Castillo García M, Urdapilleta E. A dynamical adaptation model of visual spatiotemporal processing in cones and horizontal cells. Math Biosci 2023; 366:109104. [PMID: 37918478 DOI: 10.1016/j.mbs.2023.109104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/26/2023] [Accepted: 10/29/2023] [Indexed: 11/04/2023]
Abstract
In this work, we introduce a phenomenological model for the cone-horizontal cell assembly, including spatial integration and formation of receptive field-like structures. The model extends our previous dynamical adaptation description with gain control accounting for processes in single cones, valid in severe nonlinear regimes. Here, a spatially extended feedback mechanism is introduced from horizontal cells to cones to account for experimental evidence, contributing thus to the development of a center-surround receptive field in cones and downstream bipolar cells. Feedback gain is defined on different spatial scales by weighting spatial filters: a short scale accounting for cone input to the feedback mechanism and a large scale driven by the syncytium characteristics of horizontal cells. A third spatial scale improves the description, mimicking neighboring cone-cone coupling. This overall spatial integration couples to temporal signal processing, thus obtaining a spatiotemporal model of outer retina responses capable of reproducing nonlinear features in both dimensions (space and time). The model was tested and validated using measurements on horizontal cells from different studies, with excellent performance. By its phenomenological nature, signal processing properties are inferred from model parameters. The model can be used in arrays of processing units with more complex incoming patterns of visual stimuli.
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Affiliation(s)
- Miguel Castillo García
- Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, Av. E. Bustillo 9500, R8402AGP San Carlos de Bariloche, Río Negro, Argentina
| | - Eugenio Urdapilleta
- Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, Av. E. Bustillo 9500, R8402AGP San Carlos de Bariloche, Río Negro, Argentina.
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4
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Phansalkar R, Goodwill VS, Nirschl JJ, De Lillo C, Choi J, Spurlock E, Coughlin DG, Pizzo D, Sigurdson CJ, Hiniker A, Alvarez VE, Mckee AC, Lin JH. TDP43 pathology in chronic traumatic encephalopathy retinas. Acta Neuropathol Commun 2023; 11:152. [PMID: 37737191 PMCID: PMC10515050 DOI: 10.1186/s40478-023-01650-6] [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: 06/26/2023] [Accepted: 08/30/2023] [Indexed: 09/23/2023] Open
Abstract
Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with repetitive head trauma. Brain pathology in CTE is characterized by neuronal loss, gliosis, and a distinctive pattern of neuronal accumulation of hyper-phosphorylated tau (p-tau) and phospho-TDP43 (p-TDP43). Visual anomalies have been reported by patients with CTE, but the ocular pathology underlying these symptoms is unknown. We evaluated retinal pathology in post-mortem eyes collected from 8 contact sport athletes with brain autopsy-confirmed stage IV CTE and compared their findings to retinas from 8 control patients without CTE and with no known history of head injury. Pupil-optic nerve cross sections were prepared and stained with hematoxylin and eosin (H&E), p-tau, p-TDP43, and total TDP43 by immunohistochemistry. No significant retinal degeneration was observed in CTE eyes compared to control eyes by H&E. Strong cytoplasmic p-TDP43 and total TDP43 staining was found in 6/8 CTE eyes in a subset of inner nuclear layer interneurons (INL) of the retina, while only 1/8 control eyes showed similar p-TDP43 pathology. The morphology and location of these inner nuclear layer interneurons were most compatible with retinal horizontal cells, although other retinal cell types present in INL could not be ruled out. No p-tau pathology was observed in CTE or control retinas. These findings identify novel retinal TDP43 pathology in CTE retinas and support further investigation into the role of p-TDP43 in producing visual deficits in patients with CTE.
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Affiliation(s)
| | - Vanessa S Goodwill
- Department of Pathology, University of California, San Diego, La Jolla, CA, USA
| | - Jeffrey J Nirschl
- Departments of Ophthalmology and Pathology, Stanford University, Stanford, CA, USA
| | | | - Jihee Choi
- The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Elizabeth Spurlock
- Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, MA, USA
| | - David G Coughlin
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Donald Pizzo
- Department of Pathology, University of California, San Diego, La Jolla, CA, USA
| | | | - Annie Hiniker
- Department of Pathology, University of California, San Diego, La Jolla, CA, USA
| | - Victor E Alvarez
- Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
| | - Ann C Mckee
- Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
| | - Jonathan H Lin
- Departments of Ophthalmology and Pathology, Stanford University, Stanford, CA, USA.
- VA Palo Alto Healthcare System, Palo Alto, CA, USA.
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5
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Constable PA, Lim JKH, Thompson DA. Retinal electrophysiology in central nervous system disorders. A review of human and mouse studies. Front Neurosci 2023; 17:1215097. [PMID: 37600004 PMCID: PMC10433210 DOI: 10.3389/fnins.2023.1215097] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 07/17/2023] [Indexed: 08/22/2023] Open
Abstract
The retina and brain share similar neurochemistry and neurodevelopmental origins, with the retina, often viewed as a "window to the brain." With retinal measures of structure and function becoming easier to obtain in clinical populations there is a growing interest in using retinal findings as potential biomarkers for disorders affecting the central nervous system. Functional retinal biomarkers, such as the electroretinogram, show promise in neurological disorders, despite having limitations imposed by the existence of overlapping genetic markers, clinical traits or the effects of medications that may reduce their specificity in some conditions. This narrative review summarizes the principal functional retinal findings in central nervous system disorders and related mouse models and provides a background to the main excitatory and inhibitory retinal neurotransmitters that have been implicated to explain the visual electrophysiological findings. These changes in retinal neurochemistry may contribute to our understanding of these conditions based on the findings of retinal electrophysiological tests such as the flash, pattern, multifocal electroretinograms, and electro-oculogram. It is likely that future applications of signal analysis and machine learning algorithms will offer new insights into the pathophysiology, classification, and progression of these clinical disorders including autism, attention deficit/hyperactivity disorder, bipolar disorder, schizophrenia, depression, Parkinson's, and Alzheimer's disease. New clinical applications of visual electrophysiology to this field may lead to earlier, more accurate diagnoses and better targeted therapeutic interventions benefiting individual patients and clinicians managing these individuals and their families.
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Affiliation(s)
- Paul A. Constable
- College of Nursing and Health Sciences, Caring Futures Institute, Flinders University, Adelaide, SA, Australia
| | - Jeremiah K. H. Lim
- Discipline of Optometry, School of Allied Health, University of Western Australia, Perth, WA, Australia
| | - Dorothy A. Thompson
- The Tony Kriss Visual Electrophysiology Unit, Clinical and Academic Department of Ophthalmology, Great Ormond Street Hospital for Children NHS Trust, London, United Kingdom
- UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
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6
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Zhdanov A, Constable P, Manjur SM, Dolganov A, Posada-Quintero HF, Lizunov A. OculusGraphy: Signal Analysis of the Electroretinogram in a Rabbit Model of Endophthalmitis Using Discrete and Continuous Wavelet Transforms. Bioengineering (Basel) 2023; 10:708. [PMID: 37370639 DOI: 10.3390/bioengineering10060708] [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: 05/12/2023] [Revised: 06/04/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
BACKGROUND The electroretinogram is a clinical test used to assess the function of the photoreceptors and retinal circuits of various cells in the eye, with the recorded waveform being the result of the summated response of neural generators across the retina. METHODS The present investigation involved an analysis of the electroretinogram waveform in both the time and time-frequency domains through the utilization of the discrete wavelet transform and continuous wavelet transform techniques. The primary aim of this study was to monitor and evaluate the effects of treatment in a New Zealand rabbit model of endophthalmitis via electroretinogram waveform analysis and to compare these with normal human electroretinograms. RESULTS The wavelet scalograms were analyzed using various mother wavelets, including the Daubechies, Ricker, Wavelet Biorthogonal 3.1 (bior3.1), Morlet, Haar, and Gaussian wavelets. Distinctive variances were identified in the wavelet scalograms between rabbit and human electroretinograms. The wavelet scalograms in the rabbit model of endophthalmitis showed recovery with treatment in parallel with the time-domain features. CONCLUSIONS The study compared adult, child, and rabbit electroretinogram responses using DWT and CWT, finding that adult signals had higher power than child signals, and that rabbit signals showed differences in the a-wave and b-wave depending on the type of response tested, while the Haar wavelet was found to be superior in visualizing frequency components in electrophysiological signals for following the treatment of endophthalmitis and may give additional outcome measures for the management of retinal disease.
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Affiliation(s)
- Aleksei Zhdanov
- Machine Learning and Data Analytics Lab, University of Erlangen-Nuremberg, 91052 Erlangen, Germany
- Engineering School of Information Technologies, Telecommunications and Control Systems, Ural Federal University Named after the First President of Russia B. N. Yeltsin, 620002 Yekaterinburg, Russia
| | - Paul Constable
- College of Nursing and Health Sciences, Caring Futures Institute, Flinders University, Adelaide, SA 5042, Australia
| | | | - Anton Dolganov
- Engineering School of Information Technologies, Telecommunications and Control Systems, Ural Federal University Named after the First President of Russia B. N. Yeltsin, 620002 Yekaterinburg, Russia
| | | | - Aleksander Lizunov
- Department of Functional Diagnostics, IRTC Eye Microsurgery Ekaterinburg Center, 620149 Yekaterinburg, Russia
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7
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Bhoi JD, Goel M, Ribelayga CP, Mangel SC. Circadian clock organization in the retina: From clock components to rod and cone pathways and visual function. Prog Retin Eye Res 2023; 94:101119. [PMID: 36503722 PMCID: PMC10164718 DOI: 10.1016/j.preteyeres.2022.101119] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 08/22/2022] [Accepted: 08/25/2022] [Indexed: 12/13/2022]
Abstract
Circadian (24-h) clocks are cell-autonomous biological oscillators that orchestrate many aspects of our physiology on a daily basis. Numerous circadian rhythms in mammalian and non-mammalian retinas have been observed and the presence of an endogenous circadian clock has been demonstrated. However, how the clock and associated rhythms assemble into pathways that support and control retina function remains largely unknown. Our goal here is to review the current status of our knowledge and evaluate recent advances. We describe many previously-observed retinal rhythms, including circadian rhythms of morphology, biochemistry, physiology, and gene expression. We evaluate evidence concerning the location and molecular machinery of the retinal circadian clock, as well as consider findings that suggest the presence of multiple clocks. Our primary focus though is to describe in depth circadian rhythms in the light responses of retinal neurons with an emphasis on clock control of rod and cone pathways. We examine evidence that specific biochemical mechanisms produce these daily light response changes. We also discuss evidence for the presence of multiple circadian retinal pathways involving rhythms in neurotransmitter activity, transmitter receptors, metabolism, and pH. We focus on distinct actions of two dopamine receptor systems in the outer retina, a dopamine D4 receptor system that mediates circadian control of rod/cone gap junction coupling and a dopamine D1 receptor system that mediates non-circadian, light/dark adaptive regulation of gap junction coupling between horizontal cells. Finally, we evaluate the role of circadian rhythmicity in retinal degeneration and suggest future directions for the field of retinal circadian biology.
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Affiliation(s)
- Jacob D Bhoi
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA; Neuroscience Honors Research Program, William Marsh Rice University, Houston, TX, USA
| | - Manvi Goel
- Department of Neuroscience, Wexner Medical Center, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Christophe P Ribelayga
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA; Neuroscience Honors Research Program, William Marsh Rice University, Houston, TX, USA.
| | - Stuart C Mangel
- Department of Neuroscience, Wexner Medical Center, College of Medicine, The Ohio State University, Columbus, OH, USA.
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8
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Gaynes JA, Budoff SA, Grybko MJ, Hunt JB, Poleg-Polsky A. Classical center-surround receptive fields facilitate novel object detection in retinal bipolar cells. Nat Commun 2022; 13:5575. [PMID: 36163249 PMCID: PMC9512824 DOI: 10.1038/s41467-022-32761-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/16/2022] [Indexed: 11/11/2022] Open
Abstract
Antagonistic interactions between center and surround receptive field (RF) components lie at the heart of the computations performed in the visual system. Circularly symmetric center-surround RFs are thought to enhance responses to spatial contrasts (i.e., edges), but how visual edges affect motion processing is unclear. Here, we addressed this question in retinal bipolar cells, the first visual neuron with classic center-surround interactions. We found that bipolar glutamate release emphasizes objects that emerge in the RF; their responses to continuous motion are smaller, slower, and cannot be predicted by signals elicited by stationary stimuli. In our hands, the alteration in signal dynamics induced by novel objects was more pronounced than edge enhancement and could be explained by priming of RF surround during continuous motion. These findings echo the salience of human visual perception and demonstrate an unappreciated capacity of the center-surround architecture to facilitate novel object detection and dynamic signal representation. Center-surround receptive fields are typically considered to mediate edge detection. Here, by studying retinal bipolar cells responding to flashed and moving stimuli, the authors reveal an additional function: enhanced representation of newly appearing visual items.
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Affiliation(s)
- John A Gaynes
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Samuel A Budoff
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Michael J Grybko
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Joshua B Hunt
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Alon Poleg-Polsky
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA.
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9
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Tsukamoto Y, Omi N. Multiple Invagination Patterns and Synaptic Efficacy in Primate and Mouse Rod Synaptic Terminals. Invest Ophthalmol Vis Sci 2022; 63:11. [PMID: 35819284 PMCID: PMC9287620 DOI: 10.1167/iovs.63.8.11] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Optical retina images are scaled based on eye size, which results in a linear scale ratio of 10:1 for human versus mouse and 7:1 for macaque monkey versus mouse. We examined how this scale difference correlates with the structural configuration of synaptic wiring in the rod spherule (RS) between macaque and mouse retinas compared with human data. Methods Rod bipolar cell (BC) dendrites and horizontal cell (HC) axonal processes, which invaginate the RS to form synaptic ribbon-associated triads, were examined by serial section transmission electron microscopy. Results The number of rod BC invaginating dendrites ranged 1∼4 in the macaque RS but only 1∼2 in the mouse. Approximately 40% of those dendrites bifurcated into two central elements in the macaque, but 2% of those dendrites did in the mouse. Both factors gave rise to 10 invagination patterns of BC and HC neurites in the macaque RS but only two in the mouse. Five morphological parameters: the lengths of arciform densities and ribbons, the area of the BC-RS contact, and the surface areas of BC and HC invaginating neurites, were all independent of the invagination patterns in the macaque RS. However, those parameters were significantly greater in the macaque than in the mouse by ratios of 1.5∼1.8. Conclusions The primate RS provides a more expansive BC-RS interface associated with the longer arciform density and more branched invaginating neurites of BCs and HCs than the mouse RS. The resulting greater synaptic contact area may contribute to more efficient signal transfer.
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Affiliation(s)
- Yoshihiko Tsukamoto
- Department of Biology, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo, Japan.,Studio EM-Retina, Satonaka, Nishinomiya, Hyogo, Japan.,Center for Systems Vision Science, Organization of Science and Technology, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Naoko Omi
- Studio EM-Retina, Satonaka, Nishinomiya, Hyogo, Japan
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10
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Barnes S. Visual processing: When two synaptic strata are better than one. Curr Biol 2022; 32:R129-R131. [DOI: 10.1016/j.cub.2021.12.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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11
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Vila A, Shihabeddin E, Zhang Z, Santhanam A, Ribelayga CP, O'Brien J. Synaptic Scaffolds, Ion Channels and Polyamines in Mouse Photoreceptor Synapses: Anatomy of a Signaling Complex. Front Cell Neurosci 2021; 15:667046. [PMID: 34393723 PMCID: PMC8356055 DOI: 10.3389/fncel.2021.667046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 07/05/2021] [Indexed: 12/29/2022] Open
Abstract
Synaptic signaling complexes are held together by scaffold proteins, each of which is selectively capable of interacting with a number of other proteins. In previous studies of rabbit retina, we found Synapse-Associated Protein-102 (SAP102) and Channel Associated Protein of Synapse-110 (Chapsyn110) selectively localized in the tips of horizontal cell processes at contacts with rod and cone photoreceptors, along with several interacting ion channels. We have examined the equivalent suites of proteins in mouse retina and found similarities and differences. In the mouse retina we identified Chapsyn110 as the scaffold selectively localized in the tips of horizontal cells contacting photoreceptors, with Sap102 more diffusely present. As in rabbit, the inward rectifier potassium channel Kir2.1 was present with Chapsyn110 on the tips of horizontal cell dendrites within photoreceptor invaginations, where it could provide a hyperpolarization-activated current that could contribute to ephaptic signaling in the photoreceptor synapses. Pannexin 1 and Pannexin 2, thought to play a role in ephaptic and/or pH mediated signaling, were present in the outer plexiform layer, but likely not in the horizontal cells. Polyamines regulate many ion channels and control the degree of rectification of Kir2.1 by imposing a voltage-dependent block. During the day polyamine immunolabeling was unexpectedly high in photoreceptor terminals compared to other areas of the retina. This content was significantly lower at night, when polyamine content was predominantly in Müller glia, indicating daily rhythms of polyamine content. Both rod and cone terminals displayed the same rhythm. While polyamine content was not prominent in horizontal cells, if polyamines are released, they may regulate the activity of Kir2.1 channels located in the tips of HCs. The rhythmic change in polyamine content of photoreceptor terminals suggests that a daily rhythm tunes the behavior of suites of ion channels within the photoreceptor synapses.
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Affiliation(s)
- Alejandro Vila
- Richard S. Ruiz M.D. Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Houston, TX, United States.,MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
| | - Eyad Shihabeddin
- Richard S. Ruiz M.D. Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Houston, TX, United States.,MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
| | - Zhijing Zhang
- Richard S. Ruiz M.D. Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Abirami Santhanam
- Richard S. Ruiz M.D. Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Christophe P Ribelayga
- Richard S. Ruiz M.D. Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Houston, TX, United States.,MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
| | - John O'Brien
- Richard S. Ruiz M.D. Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Houston, TX, United States.,MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
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12
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Petralia RS, Yao PJ, Kapogiannis D, Wang YX. Invaginating Structures in Synapses - Perspective. Front Synaptic Neurosci 2021; 13:685052. [PMID: 34108873 PMCID: PMC8180840 DOI: 10.3389/fnsyn.2021.685052] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 04/28/2021] [Indexed: 01/05/2023] Open
Abstract
Invaginating structures are common in the synapses of most animals. However, the details of these invaginating structures remain understudied in part because they are not well resolved in light microscopy and were often misidentified in early electron microscope (EM) studies. Utilizing experimental techniques along with the latest advances in microscopy, such as focused ion beam-scanning EM (FIB-SEM), evidence is gradually building to suggest that the synaptic invaginating structures contribute to synapse development, maintenance, and plasticity. These invaginating structures are most elaborate in synapses mediating rapid integration of signals, such as muscle contraction, mechanoreception, and vision. Here we argue that the synaptic invaginations should be considered in future studies seeking to understand their role in sensory integration and coordination, learning, and memory. We review the various types of invaginating structures in the synapses and discuss their potential functions. We also present several new examples of invaginating structures from a variety of animals including Drosophila and mice, mainly using FIB-SEM, with which we trace the form and arrangement of these structures.
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Affiliation(s)
- Ronald S. Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders/National Institutes of Health, Bethesda, MD, United States
| | - Pamela J. Yao
- Laboratory of Clinical Investigation, National Institute on Aging/National Institutes of Health, Bethesda, MD, United States
| | - Dimitrios Kapogiannis
- Laboratory of Clinical Investigation, National Institute on Aging/National Institutes of Health, Bethesda, MD, United States
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders/National Institutes of Health, Bethesda, MD, United States
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Hirano AA, Vuong HE, Kornmann HL, Schietroma C, Stella SL, Barnes S, Brecha NC. Vesicular Release of GABA by Mammalian Horizontal Cells Mediates Inhibitory Output to Photoreceptors. Front Cell Neurosci 2020; 14:600777. [PMID: 33335476 PMCID: PMC7735995 DOI: 10.3389/fncel.2020.600777] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/04/2020] [Indexed: 12/14/2022] Open
Abstract
Feedback inhibition by horizontal cells regulates rod and cone photoreceptor calcium channels that control their release of the neurotransmitter glutamate. This inhibition contributes to synaptic gain control and the formation of the center-surround antagonistic receptive fields passed on to all downstream neurons, which is important for contrast sensitivity and color opponency in vision. In contrast to the plasmalemmal GABA transporter found in non-mammalian horizontal cells, there is evidence that the mechanism by which mammalian horizontal cells inhibit photoreceptors involves the vesicular release of the inhibitory neurotransmitter GABA. Historically, inconsistent findings of GABA and its biosynthetic enzyme, L-glutamate decarboxylase (GAD) in horizontal cells, and the apparent lack of surround response block by GABAergic agents diminished support for GABA's role in feedback inhibition. However, the immunolocalization of the vesicular GABA transporter (VGAT) in the dendritic and axonal endings of horizontal cells that innervate photoreceptor terminals suggested GABA was released via vesicular exocytosis. To test the idea that GABA is released from vesicles, we localized GABA and GAD, multiple SNARE complex proteins, synaptic vesicle proteins, and Cav channels that mediate exocytosis to horizontal cell dendritic tips and axonal terminals. To address the perceived relative paucity of synaptic vesicles in horizontal cell endings, we used conical electron tomography on mouse and guinea pig retinas that revealed small, clear-core vesicles, along with a few clathrin-coated vesicles and endosomes in horizontal cell processes within photoreceptor terminals. Some small-diameter vesicles were adjacent to the plasma membrane and plasma membrane specializations. To assess vesicular release, a functional assay involving incubation of retinal slices in luminal VGAT-C antibodies demonstrated vesicles fused with the membrane in a depolarization- and calcium-dependent manner, and these labeled vesicles can fuse multiple times. Finally, targeted elimination of VGAT in horizontal cells resulted in a loss of tonic, autaptic GABA currents, and of inhibitory feedback modulation of the cone photoreceptor Cai, consistent with the elimination of GABA release from horizontal cell endings. These results in mammalian retina identify the central role of vesicular release of GABA from horizontal cells in the feedback inhibition of photoreceptors.
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Affiliation(s)
- Arlene A. Hirano
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA, United States
| | - Helen E. Vuong
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Helen L. Kornmann
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Cataldo Schietroma
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Salvatore L. Stella
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Steven Barnes
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Doheny Eye Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Nicholas C. Brecha
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA, United States
- Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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