1
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So C, Zhang T, Wang Q, Qiu C, Elie DLA, Pan F. The response of retinal ganglion cells to optical defocused visual stimuli in mouse retinas. Exp Eye Res 2024; 241:109834. [PMID: 38382575 DOI: 10.1016/j.exer.2024.109834] [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: 11/08/2023] [Revised: 01/31/2024] [Accepted: 02/16/2024] [Indexed: 02/23/2024]
Abstract
Myopia and astigmatism are two primary types of refractive errors characterized by inaccurate focusing images on the retina. This study aimed to investigate the response characteristics of Retinal Ganglion Cells (RGCs), represented by alpha (α) RGCs, when exposed to focused, simulated spherically defocused images and astigmatically defocused images projected onto mouse retinas. Negative pressure was applied to stretch the soma of RGC in vitro to simulate myopia using a 7-8 μm diameter glass microelectrode, resulting in a 5% increase in the cell's diameter. A custom-made device was utilized to project spherically (equal to ±10 and ± 20 D) and astigmatically (+6.00 D) defocused images onto the retinas. As a control for a deficient intact retinal circuit, αRGCs of connexin 36 knockout (Cx36 KO) mice were used. The response of αRGCs varied significantly in terms of spikes, excitatory postsynaptic currents (EPSCs) and capacitances under stretching conditions to mimic myopia. Significant differences in the amplitudes of EPSCs were observed in the majority of αRGCs when exposed to focused and spherically defocused images in normal and mechanically simulated myopic retinas. However, this difference was not observed in αRGCs of Cx36 KO mice. αRGCs demonstrated significant differences in response between focused and astigmatically defocused images. Once again, αRGCs of Cx36 KO mice did not display differences. αRGCs have the ability to detect focused, spherically, and astigmatically defocused images and exhibit differential responses ex vivo. Gap junction subunit Cx36 may play a crucial role in transmitting visual signals associated with developing and perceiving refractive errors.
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Affiliation(s)
- Chunghim So
- School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
| | - Ting Zhang
- Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong
| | - Qin Wang
- Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong
| | - Chunting Qiu
- School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
| | | | - Feng Pan
- School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong; Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong; Research Centre for SHARP Vision (RCSV), The Hong Kong Polytechnic University, Hong Kong; Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China.
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2
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Bonezzi PJ, Tarchick MJ, Moore BD, Renna JM. Light drives the developmental progression of outer retinal function. J Gen Physiol 2023; 155:e202213262. [PMID: 37432412 PMCID: PMC10336150 DOI: 10.1085/jgp.202213262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 02/24/2023] [Accepted: 06/08/2023] [Indexed: 07/12/2023] Open
Abstract
The complex nature of rod and cone photoreceptors and the light-evoked responsivity of bipolar cells in the mature rodent retina have been well characterized. However, little is known about the emergent light-evoked response properties of the mouse retina and the role light plays in shaping these emergent responses. We have previously demonstrated that the outer retina is responsive to green light as early as postnatal day 8 (P8). Here, we characterize the progression of both photoreceptors (rods and cones) and bipolar cell responses during development and into adulthood using ex vivo electroretinogram recordings. Our data show that the majority of photoreceptor response at P8 originates from cones and that these outputs drive second-order bipolar cell responses as early as P9. We find that the magnitude of the photoresponse increases concurrently with each passing day of postnatal development and that many functional properties of these responses, as well as the relative rod/cone contributions to the total light-evoked response, are age dependent. We compare these responses at eye opening and maturity to age-matched animals raised in darkness and found that the absence of light diminishes emergent and mature cone-to-bipolar cell signaling. Furthermore, we found cone-evoked responses to be significantly slower in dark-reared retinas. Together, this work characterizes the developmental photoresponsivity of the mouse retina while highlighting the importance of properly timed sensory input for the maturation of the first visual system synapse.
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Affiliation(s)
- Paul J. Bonezzi
- Department of Biology, The University of Akron, Akron, OH, USA
| | | | | | - Jordan M. Renna
- Department of Biology, The University of Akron, Akron, OH, USA
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3
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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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4
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Ponce-Mora A, Yuste A, Perini-Villanueva G, Miranda M, Bejarano E. Connexins Biology in the Pathophysiology of Retinal Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:229-234. [PMID: 37440038 DOI: 10.1007/978-3-031-27681-1_33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Connexins (Cx) are a family of transmembrane proteins that form gap junction intercellular channels that connect neighboring cells. These channels allow the passage of ions and other biomolecules smaller than 1 kDa, thereby synchronizing the cells both electrically and metabolically. Cxs are expressed in all retinal cell types and the diversity of Cx isoforms involved in the assembly of the channels provides a functional syncytium required for visual transduction. In this chapter, we summarize the status of current knowledge regarding Cx biology in retinal tissues and discuss how Cx dysfunction is associated with retinal disease pathophysiology. Although the contribution of Cx deficiency to retinal degeneration is not well understood, recent findings present Cx as a potential therapeutic target. Therefore, we will briefly discuss pharmacological approaches and gene therapies that are being explored to modulate Cx function and fight sight-threatening eye diseases.
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Affiliation(s)
- Alejandro Ponce-Mora
- School of Health Sciences and Veterinary School, Universidad CEU Cardenal Herrera, CEU Universities, Valencia, Spain
| | - Andrea Yuste
- School of Health Sciences and Veterinary School, Universidad CEU Cardenal Herrera, CEU Universities, Valencia, Spain
| | - Giuliana Perini-Villanueva
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA
| | - María Miranda
- School of Health Sciences and Veterinary School, Universidad CEU Cardenal Herrera, CEU Universities, Valencia, Spain
| | - Eloy Bejarano
- School of Health Sciences and Veterinary School, Universidad CEU Cardenal Herrera, CEU Universities, Valencia, Spain.
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5
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Divergent outer retinal circuits drive image and non-image visual behaviors. Cell Rep 2022; 39:111003. [PMID: 35767957 PMCID: PMC9400924 DOI: 10.1016/j.celrep.2022.111003] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/25/2022] [Accepted: 06/03/2022] [Indexed: 11/22/2022] Open
Abstract
Image- and non-image-forming vision are essential for animal behavior. Here we use genetically modified mouse lines to examine retinal circuits driving image- and non-image-functions. We describe the outer retinal circuits underlying the pupillary light response (PLR) and circadian photoentrainment, two non-image-forming behaviors. Rods and cones signal light increments and decrements through the ON and OFF pathways, respectively. We find that the OFF pathway drives image-forming vision but cannot drive circadian photoentrainment or the PLR. Cone light responses drive image formation but fail to drive the PLR. At photopic levels, rods use the primary and secondary rod pathways to drive the PLR, whereas at the scotopic and mesopic levels, rods use the primary pathway to drive the PLR, and the secondary pathway is insufficient. Circuit dynamics allow rod ON pathways to drive two non-image-forming behaviors across a wide range of light intensities, whereas the OFF pathway is potentially restricted to image formation.
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6
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Ishibashi M, Keung J, Morgans CW, Aicher SA, Carroll JR, Singer JH, Jia L, Li W, Fahrenfort I, Ribelayga CP, Massey SC. Analysis of rod/cone gap junctions from the reconstruction of mouse photoreceptor terminals. eLife 2022; 11:73039. [PMID: 35471186 PMCID: PMC9170248 DOI: 10.7554/elife.73039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 04/25/2022] [Indexed: 12/14/2022] Open
Abstract
Electrical coupling, mediated by gap junctions, contributes to signal averaging, synchronization, and noise reduction in neuronal circuits. In addition, gap junctions may also provide alternative neuronal pathways. However, because they are small and especially difficult to image, gap junctions are often ignored in large-scale 3D reconstructions. Here, we reconstruct gap junctions between photoreceptors in the mouse retina using serial blockface-scanning electron microscopy, focused ion beam-scanning electron microscopy, and confocal microscopy for the gap junction protein Cx36. An exuberant spray of fine telodendria extends from each cone pedicle (including blue cones) to contact 40-50 nearby rod spherules at sites of Cx36 labeling, with approximately 50 Cx36 clusters per cone pedicle and 2-3 per rod spherule. We were unable to detect rod/rod or cone/cone coupling. Thus, rod/cone coupling accounts for nearly all gap junctions between photoreceptors. We estimate a mean of 86 Cx36 channels per rod/cone pair, which may provide a maximum conductance of ~1200 pS, if all gap junction channels were open. This is comparable to the maximum conductance previously measured between rod/cone pairs in the presence of a dopamine antagonist to activate Cx36, suggesting that the open probability of gap junction channels can approach 100% under certain conditions.
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Affiliation(s)
- Munenori Ishibashi
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
| | - Joyce Keung
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
| | - Catherine W Morgans
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, United States
| | - Sue A Aicher
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, United States
| | - James R Carroll
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, United States
| | - Joshua H Singer
- Department of Biology, University of Maryland, College Park, College Park, United States
| | - Li Jia
- Retinal Neurophysiology Section, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Wei Li
- Retinal Neurophysiology Section, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Iris Fahrenfort
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
| | - Christophe P Ribelayga
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
| | - Stephen C Massey
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
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7
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Palumbos SD, Skelton R, McWhirter R, Mitchell A, Swann I, Heifner S, Von Stetina S, Miller DM. cAMP controls a trafficking mechanism that maintains the neuron specificity and subcellular placement of electrical synapses. Dev Cell 2021; 56:3235-3249.e4. [PMID: 34741804 DOI: 10.1016/j.devcel.2021.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 08/30/2021] [Accepted: 10/08/2021] [Indexed: 11/28/2022]
Abstract
Electrical synapses are established between specific neurons and within distinct subcellular compartments, but the mechanisms that direct gap junction assembly in the nervous system are largely unknown. Here, we show that a developmental program tunes cAMP signaling to direct the neuron-specific assembly and placement of electrical synapses in the C. elegans motor circuit. We use live-cell imaging to visualize electrical synapses in vivo and an optogenetic assay to confirm that they are functional. In ventral A class (VA) motor neurons, the UNC-4 transcription factor blocks expression of cAMP antagonists that promote gap junction miswiring. In unc-4 mutants, VA electrical synapses are established with an alternative synaptic partner and are repositioned from the VA axon to soma. cAMP counters these effects by driving gap junction trafficking into the VA axon for electrical synapse assembly. Thus, our experiments establish that cAMP regulates gap junction trafficking for the biogenesis of functional electrical synapses.
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Affiliation(s)
- Sierra D Palumbos
- Neuroscience Program, Vanderbilt University, Nashville, TN 37212, USA
| | - Rachel Skelton
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37212, USA
| | - Rebecca McWhirter
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37212, USA
| | - Amanda Mitchell
- Vanderbilt Summer Science Academy, Vanderbilt University, Nashville, TN 37212, USA
| | - Isaiah Swann
- Vanderbilt Summer Science Academy, Vanderbilt University, Nashville, TN 37212, USA
| | | | - Stephen Von Stetina
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37212, USA
| | - David M Miller
- Neuroscience Program, Vanderbilt University, Nashville, TN 37212, USA; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37212, USA.
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8
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Talukdar S, Emdad L, Das SK, Fisher PB. GAP junctions: multifaceted regulators of neuronal differentiation. Tissue Barriers 2021; 10:1982349. [PMID: 34651545 DOI: 10.1080/21688370.2021.1982349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Gap junctions are intercellular membrane channels consisting of connexin proteins, which contribute to direct cytoplasmic exchange of small molecules, substrates and metabolites between adjacent cells. These channels play important roles in neuronal differentiation, maintenance, survival and function. Gap junctions regulate differentiation of neurons from embryonic, neural and induced pluripotent stem cells. In addition, they control transdifferentiation of neurons from mesenchymal stem cells. The expression and levels of several connexins correlate with cell cycle changes and different stages of neurogenesis. Connexins such as Cx36, Cx45, and Cx26, play a crucial role in neuronal function. Several connexin knockout mice display lethal or severely impaired phenotypes. Aberrations in connexin expression is frequently associated with various neurodegenerative disorders. Gap junctions also act as promising therapeutic targets for neuronal regenerative medicine, because of their role in neural stem cell integration, injury and remyelination.
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Affiliation(s)
- Sarmistha Talukdar
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.,Vcu Institute of Molecular Medicine, Richmond, VA, United States
| | - Luni Emdad
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.,Vcu Institute of Molecular Medicine, Richmond, VA, United States.,Vcu Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States
| | - Swadesh K Das
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.,Vcu Institute of Molecular Medicine, Richmond, VA, United States.,Vcu Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States
| | - Paul B Fisher
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.,Vcu Institute of Molecular Medicine, Richmond, VA, United States.,Vcu Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States
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9
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Fusz K, Kovács-Öller T, Kóbor P, Szabó-Meleg E, Völgyi B, Buzás P, Telkes I. Regional Variation of Gap Junctional Connections in the Mammalian Inner Retina. Cells 2021; 10:2396. [PMID: 34572046 PMCID: PMC8466939 DOI: 10.3390/cells10092396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/04/2021] [Accepted: 09/07/2021] [Indexed: 11/24/2022] Open
Abstract
The retinas of many species show regional specialisations that are evident in the differences in the processing of visual input from different parts of the visual field. Regional specialisation is thought to reflect an adaptation to the natural visual environment, optical constraints, and lifestyle of the species. Yet, little is known about regional differences in synaptic circuitry. Here, we were interested in the topographical distribution of connexin-36 (Cx36), the major constituent of electrical synapses in the retina. We compared the retinas of mice, rats, and cats to include species with different patterns of regional specialisations in the analysis. First, we used the density of Prox1-immunoreactive amacrine cells as a marker of any regional specialisation, with higher cell density signifying more central regions. Double-labelling experiments showed that Prox1 is expressed in AII amacrine cells in all three species. Interestingly, large Cx36 plaques were attached to about 8-10% of Prox1-positive amacrine cell somata, suggesting the strong electrical coupling of pairs or small clusters of cell bodies. When analysing the regional changes in the volumetric density of Cx36-immunoreactive plaques, we found a tight correlation with the density of Prox1-expressing amacrine cells in the ON, but not in the OFF sublamina in all three species. The results suggest that the relative contribution of electrical synapses to the ON- and OFF-pathways of the retina changes with retinal location, which may contribute to functional ON/OFF asymmetries across the visual field.
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Affiliation(s)
- Katalin Fusz
- Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary; (K.F.); (P.K.); (I.T.)
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary; (T.K.-Ö.); (E.S.-M.); (B.V.)
- Centre for Neuroscience, University of Pécs, 7624 Pécs, Hungary
| | - Tamás Kovács-Öller
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary; (T.K.-Ö.); (E.S.-M.); (B.V.)
- Centre for Neuroscience, University of Pécs, 7624 Pécs, Hungary
- MTA-PTE NAP-2 Retinal Electrical Synapses Research Group, 7624 Pécs, Hungary
| | - Péter Kóbor
- Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary; (K.F.); (P.K.); (I.T.)
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary; (T.K.-Ö.); (E.S.-M.); (B.V.)
- Centre for Neuroscience, University of Pécs, 7624 Pécs, Hungary
| | - Edina Szabó-Meleg
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary; (T.K.-Ö.); (E.S.-M.); (B.V.)
- Institute of Biophysics, Medical School, University of Pécs, 7624 Pécs, Hungary
| | - Béla Völgyi
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary; (T.K.-Ö.); (E.S.-M.); (B.V.)
- Centre for Neuroscience, University of Pécs, 7624 Pécs, Hungary
- MTA-PTE NAP-2 Retinal Electrical Synapses Research Group, 7624 Pécs, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, 7624 Pécs, Hungary
| | - Péter Buzás
- Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary; (K.F.); (P.K.); (I.T.)
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary; (T.K.-Ö.); (E.S.-M.); (B.V.)
- Centre for Neuroscience, University of Pécs, 7624 Pécs, Hungary
| | - Ildikó Telkes
- Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary; (K.F.); (P.K.); (I.T.)
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary; (T.K.-Ö.); (E.S.-M.); (B.V.)
- Centre for Neuroscience, University of Pécs, 7624 Pécs, Hungary
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10
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Abtout A, Fain G, Reingruber J. Analysis of waveform and amplitude of mouse rod and cone flash responses. J Physiol 2021; 599:3295-3312. [PMID: 33977528 DOI: 10.1113/jp281225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/28/2021] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Most vertebrate eyes have rod and cone photoreceptors, which use a signal transduction pathway consisting of many biological processes to transform light into an electrical response. We dissect and quantify the contribution of each of these processes to the photoreceptor light response by using a novel method of analysis that provides an analytical solution for the entire time course of the dim-flash light response. We find that the shape of the light response is exclusively controlled by deactivation parameters. Activation parameters scale this shape and alter the response amplitude. We show that the rising phase of the response depends on Ca2+ feedback, and we identify the deactivation parameters that control the recovery phase of the response. We devise new methods to extract values for deactivation and activation parameters from a separate analysis of response shape and response amplitude. ABSTRACT Vertebrate eyes have rod and cone photoreceptors, which use a complex transduction pathway comprising many biological processes to transform the absorption of light into an electrical response. A fundamental question in sensory transduction is how these processes contribute to the response. To study this question, we use a well-accepted phototransduction model, which we analyse with a novel method based on the log transform of the current. We derive an analytical solution that describes the entire time course of the photoreceptor response to dim flashes of light. We use this solution to dissect and quantify the contribution of each process to the response. We find that the entire dim-flash response is proportional to the flash intensity. By normalizing responses to unit amplitude, we define a waveform that is independent of the light intensity and characterizes the invariant shape of dim-flash responses. We show that this waveform is exclusively determined by deactivation rates; activation rates only scale the waveform and affect the amplitude. This analysis corrects a previous assumption that the rising phase is determined entirely by activation rates. We further show that the rising phase depends on Ca2+ feedback to the cyclase, contrary to current belief. We identify the deactivation rates that control the recovery phase of the response, and we devise new methods to extract activation and deactivation rates from an analysis of response shape and response amplitude. In summary, we provide a comprehensive understanding of how the various transduction processes produce the cellular response.
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Affiliation(s)
- Annia Abtout
- Institut de Biologie de l'École Normale Supérieure, Paris, France
| | - Gordon Fain
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California, USA.,Department of Ophthalmology and Stein Eye Institute, University of California, Los Angeles, California, USA
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11
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Quint WH, Tadema KCD, de Vrieze E, Lukowicz RM, Broekman S, Winkelman BHJ, Hoevenaars M, de Gruiter HM, van Wijk E, Schaeffel F, Meester-Smoor M, Miller AC, Willemsen R, Klaver CCW, Iglesias AI. Loss of Gap Junction Delta-2 (GJD2) gene orthologs leads to refractive error in zebrafish. Commun Biol 2021; 4:676. [PMID: 34083742 PMCID: PMC8175550 DOI: 10.1038/s42003-021-02185-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 05/04/2021] [Indexed: 12/20/2022] Open
Abstract
Myopia is the most common developmental disorder of juvenile eyes, and it has become an increasing cause of severe visual impairment. The GJD2 locus has been consistently associated with myopia in multiple independent genome-wide association studies. However, despite the strong genetic evidence, little is known about the functional role of GJD2 in refractive error development. Here, we find that depletion of gjd2a (Cx35.5) or gjd2b (Cx35.1) orthologs in zebrafish, cause changes in the biometry and refractive status of the eye. Our immunohistological and scRNA sequencing studies show that Cx35.5 (gjd2a) is a retinal connexin and its depletion leads to hyperopia and electrophysiological changes in the retina. These findings support a role for Cx35.5 (gjd2a) in the regulation of ocular biometry. Cx35.1 (gjd2b) has previously been identified in the retina, however, we found an additional lenticular role. Lack of Cx35.1 (gjd2b) led to a nuclear cataract that triggered axial elongation. Our results provide functional evidence of a link between gjd2 and refractive error. Quint et al. use zebrafish lines deficient in one of two orthologs of the Gap Junction Delta-2 (GJD2) gene, which is associated with myopia by genome-wide association studies. They link gjd2 with refractive error and report evidence to suggest that gjd2a plays a role in ocular biometry whilst gjd2b, previously found in the retina, possesses an additional lenticular role.
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Affiliation(s)
- Wim H Quint
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands. .,Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands.
| | - Kirke C D Tadema
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Erik de Vrieze
- Department of Otorhinolaryngology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, Netherlands
| | - Rachel M Lukowicz
- Institute of Neuroscience, University of Oregon, Eugene, United States
| | - Sanne Broekman
- Department of Otorhinolaryngology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, Netherlands
| | - Beerend H J Winkelman
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Cerebellar Coordination and Cognition, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Melanie Hoevenaars
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Erwin van Wijk
- Department of Otorhinolaryngology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, Netherlands
| | - Frank Schaeffel
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.,Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
| | - Magda Meester-Smoor
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Adam C Miller
- Institute of Neuroscience, University of Oregon, Eugene, United States
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.,Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland.,Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Adriana I Iglesias
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands. .,Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands.
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12
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Cangiano L, Asteriti S. Interphotoreceptor coupling: an evolutionary perspective. Pflugers Arch 2021; 473:1539-1554. [PMID: 33988778 PMCID: PMC8370920 DOI: 10.1007/s00424-021-02572-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/13/2021] [Accepted: 04/23/2021] [Indexed: 12/16/2022]
Abstract
In the vertebrate retina, signals generated by cones of different spectral preference and by highly sensitive rod photoreceptors interact at various levels to extract salient visual information. The first opportunity for such interaction is offered by electrical coupling of the photoreceptors themselves, which is mediated by gap junctions located at the contact points of specialised cellular processes: synaptic terminals, telodendria and radial fins. Here, we examine the evolutionary pressures for and against interphotoreceptor coupling, which are likely to have shaped how coupling is deployed in different species. The impact of coupling on signal to noise ratio, spatial acuity, contrast sensitivity, absolute and increment threshold, retinal signal flow and colour discrimination is discussed while emphasising available data from a variety of vertebrate models spanning from lampreys to primates. We highlight the many gaps in our knowledge, persisting discrepancies in the literature, as well as some major unanswered questions on the actual extent and physiological role of cone-cone, rod-cone and rod-rod communication. Lastly, we point toward limited but intriguing evidence suggestive of the ancestral form of coupling among ciliary photoreceptors.
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Affiliation(s)
- Lorenzo Cangiano
- Dept. of Translational Research, University of Pisa, Via San Zeno 31, 56123, Pisa, Italy.
| | - Sabrina Asteriti
- Dept. of Translational Research, University of Pisa, Via San Zeno 31, 56123, Pisa, Italy
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13
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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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14
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González-Casanova J, Schmachtenberg O, Martínez AD, Sanchez HA, Harcha PA, Rojas-Gomez D. An Update on Connexin Gap Junction and Hemichannels in Diabetic Retinopathy. Int J Mol Sci 2021; 22:ijms22063194. [PMID: 33801118 PMCID: PMC8004116 DOI: 10.3390/ijms22063194] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 03/06/2021] [Accepted: 03/10/2021] [Indexed: 01/10/2023] Open
Abstract
Diabetic retinopathy (DR) is one of the main causes of vision loss in the working age population. It is characterized by a progressive deterioration of the retinal microvasculature, caused by long-term metabolic alterations inherent to diabetes, leading to a progressive loss of retinal integrity and function. The mammalian retina presents an orderly layered structure that executes initial but complex visual processing and analysis. Gap junction channels (GJC) forming electrical synapses are present in each retinal layer and contribute to the communication between different cell types. In addition, connexin hemichannels (HCs) have emerged as relevant players that influence diverse physiological and pathological processes in the retina. This article highlights the impact of diabetic conditions on GJC and HCs physiology and their involvement in DR pathogenesis. Microvascular damage and concomitant loss of endothelial cells and pericytes are related to alterations in gap junction intercellular communication (GJIC) and decreased connexin 43 (Cx43) expression. On the other hand, it has been shown that the expression and activity of HCs are upregulated in DR, becoming a key element in the establishment of proinflammatory conditions that emerge during hyperglycemia. Hence, novel connexin HCs blockers or drugs to enhance GJIC are promising tools for the development of pharmacological interventions for diabetic retinopathy, and initial in vitro and in vivo studies have shown favorable results in this regard.
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Affiliation(s)
- Jorge González-Casanova
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago 8910060, Chile;
| | - Oliver Schmachtenberg
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile;
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (A.D.M.); (H.A.S.); (P.A.H.)
| | - Helmuth A. Sanchez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (A.D.M.); (H.A.S.); (P.A.H.)
| | - Paloma A. Harcha
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (A.D.M.); (H.A.S.); (P.A.H.)
| | - Diana Rojas-Gomez
- Escuela de Nutrición y Dietética, Facultad de Medicina, Universidad Andres Bello, Santiago 8370146, Chile
- Correspondence: ; Tel.: +56-2-26618559
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15
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Light responses of mammalian cones. Pflugers Arch 2021; 473:1555-1568. [PMID: 33742309 DOI: 10.1007/s00424-021-02551-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 02/28/2021] [Accepted: 03/03/2021] [Indexed: 12/24/2022]
Abstract
Cone photoreceptors provide the foundation of most of human visual experience, but because they are smaller and less numerous than rods in most mammalian retinas, much less is known about their physiology. We describe new techniques and approaches which are helping to provide a better understanding of cone function. We focus on several outstanding issues, including the identification of the features of the phototransduction cascade that are responsible for the more rapid kinetics and decreased sensitivity of the cone response, the roles of inner-segment voltage-gated and Ca2+-activated channels, the means by which cones remain responsive even in the brightest illumination, mechanisms of cone visual pigment regeneration in constant light, and energy consumption of cones in comparison to that of rods.
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16
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Asteriti S, Cangiano L. Versatile bipolar temperature controller for custom in vitro applications. HARDWAREX 2020; 8:e00155. [PMID: 33615085 PMCID: PMC7874220 DOI: 10.1016/j.ohx.2020.e00155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/26/2020] [Accepted: 10/28/2020] [Indexed: 06/12/2023]
Abstract
Effective temperature control is crucial in many studies of isolated biological tissues, with preparations often requiring specialized holding chambers. In these situations, the design flexibility and optimizations offered by a custom made temperature controller may be preferable over a commercial model. We present a versatile controller for heating and cooling applications, providing simple step-by-step instructions to mathematically model your specific system and optimize controller parameters. The apparatus uses analog components and linear stages to simplify circuit comprehension and customization, achieving fast transitions with small static errors and overshoots over a wide range of temperatures without readjustment. A fully featured rackable enclosure is complemented by two temperature probes based on the LMT70A linear microchip sensor (for the control loop and for bath monitoring). BNC outputs provide scaled probe signals for continuous temperature data acquisition. The maximum achievable power output of the controller is -23.5 W/+22.0 W (-4.7 V/+4.4 V, ±5.0 A), sufficient to bring a well designed holder for standard 35 mm chambers from 23 °C up to 37 °C in ~1 min and down to 3 °C in ~4 min. Any biologist with some technical prowess should be able to follow our instructions from modeling to assembly and calibration.
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Affiliation(s)
- Sabrina Asteriti
- Dept. of Translational Research, University of Pisa, Pisa, Italy
- Dept. of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Lorenzo Cangiano
- Dept. of Translational Research, University of Pisa, Pisa, Italy
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17
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Li Y, Cohen ED, Qian H. Rod and Cone Coupling Modulates Photopic ERG Responses in the Mouse Retina. Front Cell Neurosci 2020; 14:566712. [PMID: 33100974 PMCID: PMC7546330 DOI: 10.3389/fncel.2020.566712] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/31/2020] [Indexed: 11/13/2022] Open
Abstract
Light adaptation changes both the sensitivity and maximum amplitude (Rmax) of the mouse photopic electroretinogram (ERG) b-wave. Using the ERG, we examined how modulation of gap junctional coupling between rod and cones alters the light-adapted ERG. To measure changes, a b-wave light adaptation enhancement factor (LAEF), was defined as the ratio of Rmax after 15 min light adaptation to Rmax recorded at the onset of an adapting light. For wild-type mice (WT), the LAEF averaged 2.64 ± 0.29, however, it was significantly reduced (1.06 ± 0.04) for connexin 36 knock out (Cx36KO) mice, which lack electrical coupling between photoreceptors. Wild type mice intraocularly injected with meclofenamic acid (MFA), a gap junction blocker, also showed a significantly reduced LAEF. Degeneration of rod photoreceptors significantly alters the effects of light adaptation on the photopic ERG response. Rd10 mice at P21, with large portions of their rod photoreceptors present in the retina, exhibited a similar b-wave enhancement as wildtype controls, with a LAEF of 2.55 ± 0.19. However, by P31 with most of their rod photoreceptors degenerated, rd10 mice had a much reduced b-wave enhancement during light-adaptation (LAEF of 1.54 ± 0.12). Flicker ERG responses showed a higher temporal amplitude in mesopic conditions for WT than those of Cx36KO mice, suggesting rod-cone coupling help high-frequency signals to pass from rods to cone pathways in the retina. In conclusion, our study provides a novel method to noninvasively measure the dynamics and modulation by the light adaptation for rod-cone gap junctional coupling in intact eyes.
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Affiliation(s)
- Yichao Li
- Visual Function Core, National Eye Institute (NEI), National Institutes of Health, Bethesda, MD, United States
| | - Ethan D Cohen
- Division of Biomedical Physics, Office of Science and Engineering Labs, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, United States
| | - Haohua Qian
- Visual Function Core, National Eye Institute (NEI), National Institutes of Health, Bethesda, MD, United States
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18
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Reingruber J, Ingram NT, Griffis KG, Fain GL. A kinetic analysis of mouse rod and cone photoreceptor responses. J Physiol 2020; 598:3747-3763. [PMID: 32557629 PMCID: PMC7484371 DOI: 10.1113/jp279524] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 06/08/2020] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS Most vertebrate eyes have rods for dim-light vision and cones for brighter light and higher temporal sensitivity. Rods evolved from cone-like precursors through expression of different transduction genes or the same genes at different expression levels, but we do not know which molecular differences were most important. We approached this problem by analysing rod and cone responses with the same model but with different values for model parameters. We showed that, in addition to outer-segment volume, the most important differences between rods and cones are: (1) decreased transduction gain, reflecting smaller amplification in the G-protein cascade; (2) a faster rate of turnover of the second messenger cGMP in darkness; and (3) an accelerated rate of decay of the effector enzyme phosphodiesterase and perhaps also of activated visual pigment. We believe our analysis has identified the principal alterations during evolution responsible for the duplex retina. ABSTRACT Most vertebrates have rod and cone photoreceptors, which differ in their sensitivity and response kinetics. We know that rods evolved from cone-like precursors through the expression of different transduction genes or the same genes at different levels, but we do not know which molecular differences were most important. We have approached this problem in mouse retina by analysing the kinetic differences between rod flash responses and recent voltage-clamp recordings of cone flash responses, using a model incorporating the principal features of photoreceptor transduction. We apply a novel method of analysis using the log-transform of the current, and we ask which of the model's dynamic parameters need be changed to transform the flash response of a rod into that of a cone. The most important changes are a decrease in the gain of the response, reflecting a reduction in amplification of the transduction cascade; an increase in the rate of turnover of cGMP in darkness; and an increase in the rate of decay of activated phosphodiesterase, with perhaps also an increase in the rate of decay of light-activated visual pigment. Although we cannot exclude other differences, and in particular alterations in the Ca2+ economy of the photoreceptors, we believe that we have identified the kinetic parameters principally responsible for the differences in the flash responses of the two kinds of photoreceptors, which were likely during evolution to have resulted in the duplex retina.
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Affiliation(s)
- Jürgen Reingruber
- Institut de Biologie de l’École Normale Supérieure, 46 rue d’Ulm, 75005 Paris, France
| | - Norianne T. Ingram
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095–7239, USA
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, CA 90095–7000, USA
| | - Khris G. Griffis
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, CA 90095–7000, USA
| | - Gordon L. Fain
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095–7239, USA
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, CA 90095–7000, USA
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19
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Jin N, Zhang Z, Keung J, Youn SB, Ishibashi M, Tian LM, Marshak DW, Solessio E, Umino Y, Fahrenfort I, Kiyama T, Mao CA, You Y, Wei H, Wu J, Postma F, Paul DL, Massey SC, Ribelayga CP. Molecular and functional architecture of the mouse photoreceptor network. SCIENCE ADVANCES 2020; 6:eaba7232. [PMID: 32832605 PMCID: PMC7439306 DOI: 10.1126/sciadv.aba7232] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
Mouse photoreceptors are electrically coupled via gap junctions, but the relative importance of rod/rod, cone/cone, or rod/cone coupling is unknown. Furthermore, while connexin36 (Cx36) is expressed by cones, the identity of the rod connexin has been controversial. We report that FACS-sorted rods and cones both express Cx36 but no other connexins. We created rod- and cone-specific Cx36 knockout mice to dissect the photoreceptor network. In the wild type, Cx36 plaques at rod/cone contacts accounted for more than 95% of photoreceptor labeling and paired recordings showed the transjunctional conductance between rods and cones was ~300 pS. When Cx36 was eliminated on one side of the gap junction, in either conditional knockout, Cx36 labeling and rod/cone coupling were almost abolished. We could not detect direct rod/rod coupling, and cone/cone coupling was minor. Rod/cone coupling is so prevalent that indirect rod/cone/rod coupling via the network may account for previous reports of rod coupling.
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Affiliation(s)
- Nange Jin
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Zhijing Zhang
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Joyce Keung
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Sean B. Youn
- Summer Research Program, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Undergraduate Program, William Marsh Rice University, Houston, TX, USA
| | - Munenori Ishibashi
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Lian-Ming Tian
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - David W. Marshak
- Department of Neurobiology and Anatomy, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Neuroscience Research Center, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Program in Neuroscience, Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Eduardo Solessio
- Center for Vision Research and SUNY Eye Institute, Department of Ophthalmology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Yumiko Umino
- Center for Vision Research and SUNY Eye Institute, Department of Ophthalmology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Iris Fahrenfort
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Takae Kiyama
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Chai-An Mao
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Neuroscience Research Center, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Program in Neuroscience, Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Yanan You
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA
- Center for Stem Cell and Regenerative Medicine, The University of Texas Brown Foundation Institute of Molecular Medicine, Houston, TX, USA
| | - Haichao Wei
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA
- Center for Stem Cell and Regenerative Medicine, The University of Texas Brown Foundation Institute of Molecular Medicine, Houston, TX, USA
| | - Jiaqian Wu
- Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Program in Neuroscience, Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA
- Center for Stem Cell and Regenerative Medicine, The University of Texas Brown Foundation Institute of Molecular Medicine, Houston, TX, USA
| | - Friso Postma
- Department of Neurobiology, Medical School, Harvard University, Boston, MA, USA
| | - David L. Paul
- Department of Neurobiology, Medical School, Harvard University, Boston, MA, USA
| | - Stephen C. Massey
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Summer Research Program, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Neuroscience Research Center, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Program in Neuroscience, Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Elizabeth Morford Distinguished Chair in Ophthalmology and Research Director, Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, 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
- Summer Research Program, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Neuroscience Research Center, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Program in Neuroscience, Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Program in Biochemistry and Cellular Biology, Graduate School of Biomedical Sciences, MD Anderson Cancer Center/UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
- Bernice Weingarten Chair in Ophthalmology, Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA
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20
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Smedowski A, Akhtar S, Liu X, Pietrucha‐Dutczak M, Podracka L, Toropainen E, Alkanaan A, Ruponen M, Urtti A, Varjosalo M, Kaarniranta K, Lewin‐Kowalik J. Electrical synapses interconnecting axons revealed in the optic nerve head - a novel model of gap junctions' involvement in optic nerve function. Acta Ophthalmol 2020; 98:408-417. [PMID: 31602808 PMCID: PMC7318195 DOI: 10.1111/aos.14272] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 09/14/2019] [Indexed: 01/14/2023]
Abstract
PURPOSE To characterize newly discovered electrical synapses, formed by connexin (Cx) 36 and 45, between neighbouring axons within the optic nerve head. METHODS Twenty-five Wistar rats were killed by CO2 inhalation. Proximal and distal optic nerve (ON) stumps were collected and processed for immunostainings, electron microscopy (EM) with immunogold labelling, PCR and Western blots (WB). Additional 15 animals were deeply anaesthetized, and flash visual evoked potentials (fVEP) after retrobulbar injection of saline (negative control) or 100 μm meclofenamic acid solution (gap junctions' blocker) were recorded. Human paraffin cross-sections of eyeballs for immunostainings were obtained from the Human Eye Biobank for Research. RESULTS Immunostainings of both rat and human ON revealed the presence of Cx45 and 36 colocalizing with β3-tubulin, but not with glial fibrillary acidic protein (GFAP). In WB, Cx36 content in optic nerve was approximately halved when compared with retina (0.58 ± 0.005 in proximal stump and 0.44 ± 0.02 in distal stump), Cx45 showed higher levels (0.68 ± 0.01 in proximal stump and 0.9 ± 0.07 in distal stump). In immunogold-EM of optic nerve sections, we found electric synapses (formed mostly by Cx45) directly coupling neighbouring axons. In fVEP, blocking of gap junctions with meclofenamic acid resulted in significant prolongation of the latency of P1 wave up to 160% after 30 min (p < 0.001). CONCLUSIONS Optic nerve (ON) axons are equipped with electrical synapses composed of neuronal connexins, especially Cx45, creating direct morphological and functional connections between each other. This finding could have substantial implications for understanding of the pathogenesis of various optic neuropathies and identifies a new potential target for a therapeutic approach.
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Affiliation(s)
- Adrian Smedowski
- Department of PhysiologySchool of Medicine in KatowiceMedical University of SilesiaKatowicePoland
| | - Saeed Akhtar
- Department of OptometryCollege of Applied Medical SciencesKing Saud UniversityRiyadhKingdom of Saudi Arabia
| | - Xiaonan Liu
- Institute of BiotechnologyUniversity of HelsinkiHelsinkiFinland
| | - Marita Pietrucha‐Dutczak
- Department of PhysiologySchool of Medicine in KatowiceMedical University of SilesiaKatowicePoland
| | - Lucia Podracka
- School of PharmacyUniversity of Eastern FinlandKuopioFinland
| | | | - Aljoharah Alkanaan
- Department of OptometryCollege of Applied Medical SciencesKing Saud UniversityRiyadhKingdom of Saudi Arabia
| | - Marika Ruponen
- School of PharmacyUniversity of Eastern FinlandKuopioFinland
| | - Arto Urtti
- School of PharmacyUniversity of Eastern FinlandKuopioFinland
| | | | - Kai Kaarniranta
- Department of OphthalmologyUniversity of Eastern FinlandKuopioFinland,Department of OphthalmologyKuopio University HospitalKuopioFinland
| | - Joanna Lewin‐Kowalik
- Department of PhysiologySchool of Medicine in KatowiceMedical University of SilesiaKatowicePoland
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21
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Network Architecture of Gap Junctional Coupling among Parallel Processing Channels in the Mammalian Retina. J Neurosci 2020; 40:4483-4511. [PMID: 32332119 DOI: 10.1523/jneurosci.1810-19.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 03/27/2020] [Accepted: 04/12/2020] [Indexed: 01/04/2023] Open
Abstract
Gap junctions are ubiquitous throughout the nervous system, mediating critical signal transmission and integration, as well as emergent network properties. In mammalian retina, gap junctions within the Aii amacrine cell-ON cone bipolar cell (CBC) network are essential for night vision, modulation of day vision, and contribute to visual impairment in retinal degenerations, yet neither the extended network topology nor its conservation is well established. Here, we map the network contribution of gap junctions using a high-resolution connectomics dataset of an adult female rabbit retina. Gap junctions are prominent synaptic components of ON CBC classes, constituting 5%-25% of all axonal synaptic contacts. Many of these mediate canonical transfer of rod signals from Aii cells to ON CBCs for night vision, and we find that the uneven distribution of Aii signals to ON CBCs is conserved in rabbit, including one class entirely lacking direct Aii coupling. However, the majority of gap junctions formed by ON CBCs unexpectedly occur between ON CBCs, rather than with Aii cells. Such coupling is extensive, creating an interconnected network with numerous lateral paths both within, and particularly across, these parallel processing streams. Coupling patterns are precise with ON CBCs accepting and rejecting unique combinations of partnerships according to robust rulesets. Coupling specificity extends to both size and spatial topologies, thereby rivaling the synaptic specificity of chemical synapses. These ON CBC coupling motifs dramatically extend the coupled Aii-ON CBC network, with implications for signal flow in both scotopic and photopic retinal networks during visual processing and disease.SIGNIFICANCE STATEMENT Electrical synapses mediated by gap junctions are fundamental components of neural networks. In retina, coupling within the Aii-ON CBC network shapes visual processing in both the scotopic and photopic networks. In retinal degenerations, these same gap junctions mediate oscillatory activity that contributes to visual impairment. Here, we use high-resolution connectomics strategies to identify gap junctions and cellular partnerships. We describe novel, pervasive motifs both within and across classes of ON CBCs that dramatically extend the Aii-ON CBC network. These motifs are highly specific with implications for both signal processing within the retina and therapeutic interventions for blinding conditions. These findings highlight the underappreciated contribution of coupling motifs in retinal circuitry and the necessity of their detection in connectomics studies.
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Martin EA, Lasseigne AM, Miller AC. Understanding the Molecular and Cell Biological Mechanisms of Electrical Synapse Formation. Front Neuroanat 2020; 14:12. [PMID: 32372919 PMCID: PMC7179694 DOI: 10.3389/fnana.2020.00012] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 03/09/2020] [Indexed: 12/20/2022] Open
Abstract
In this review article, we will describe the recent advances made towards understanding the molecular and cell biological mechanisms of electrical synapse formation. New evidence indicates that electrical synapses, which are gap junctions between neurons, can have complex molecular compositions including protein asymmetries across joined cells, diverse morphological arrangements, and overlooked similarities with other junctions, all of which indicate new potential roles in neurodevelopmental disease. Aquatic organisms, and in particular the vertebrate zebrafish, have proven to be excellent models for elucidating the molecular mechanisms of electrical synapse formation. Zebrafish will serve as our main exemplar throughout this review and will be compared with other model organisms. We highlight the known cell biological processes that build neuronal gap junctions and compare these with the assemblies of adherens junctions, tight junctions, non-neuronal gap junctions, and chemical synapses to explore the unknown frontiers remaining in our understanding of the critical and ubiquitous electrical synapse.
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Affiliation(s)
- E Anne Martin
- Department of Biology, Institute of Neuroscience, University of Oregon, Eugene, OR, United States
| | - Abagael M Lasseigne
- Department of Biology, Institute of Neuroscience, University of Oregon, Eugene, OR, United States
| | - Adam C Miller
- Department of Biology, Institute of Neuroscience, University of Oregon, Eugene, OR, United States
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Ingram NT, Sampath AP, Fain GL. Voltage-clamp recordings of light responses from wild-type and mutant mouse cone photoreceptors. J Gen Physiol 2019; 151:1287-1299. [PMID: 31562185 PMCID: PMC6829558 DOI: 10.1085/jgp.201912419] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/15/2019] [Accepted: 08/30/2019] [Indexed: 01/16/2023] Open
Abstract
We describe the first extensive study of voltage-clamp current responses of cone photoreceptors in unlabeled, dark-adapted mouse retina using only the position and appearance of cone somata as a guide. Identification was confirmed from morphology after dye filling. Photocurrents recorded from wild-type mouse cones were biphasic with a fast cone component and a slower rod component. The rod component could be eliminated with dim background light and was not present in mouse lines lacking the rod transducin-α subunit (Gnat1-/- ) or connexin 36 (Cx36-/- ). Cones from Gnat1-/- or Cx36-/- mice had resting membrane potentials between -45 and -55 mV, peak photocurrents of 20-25 picoamps (pA) at a membrane potential Vm = -50 mV, sensitivities 60-70 times smaller than rods, and a total membrane capacitance two to four times greater than rods. The rate of activation (amplification constant) was largely independent of the brightness of the flash and was 1-2 s-2, less than half that of rods. The role of Ca2+-dependent transduction modulation was investigated by recording from cones in mice lacking rod transducin (Gnat1), recoverin, and/or the guanylyl-cyclase-activating proteins (GCAPs). In confirmation of previous results, responses of Gnat1-/- ;Gcaps-/- cones and triple-mutant Gnat1-/- ;Gcaps-/- ;Rv-/- cones recovered more slowly both to light flashes and steps and were more sensitive than cones expressing the GCAPs. Cones from all four mouse lines showed significant recovery and escaped saturation even in bright background light. This recovery occurred too rapidly to be caused by pigment bleaching or metaII decay and appears to reflect some modulation of response inactivation in addition to those produced by recoverin and the GCAPs. Our experiments now make possible a more detailed understanding of the cellular physiology of mammalian cone photoreceptors and the role of conductances in the inner and outer segment in producing cone light responses.
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Affiliation(s)
- Norianne T Ingram
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA
| | - Alapakkam P Sampath
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA
| | - Gordon L Fain
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA
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Li L. Circadian Vision in Zebrafish: From Molecule to Cell and from Neural Network to Behavior. J Biol Rhythms 2019; 34:451-462. [DOI: 10.1177/0748730419863917] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Most visual system functions, such as opsin gene expression, retinal neural transmission, light perception, and visual sensitivity, display robust day-night rhythms. The rhythms persist in constant lighting conditions, suggesting the involvement of endogenous circadian clocks. While the circadian pacemakers that control the rhythms of animal behaviors are mostly found in the forebrain and midbrain, self-sustained circadian oscillators are also present in the neural retina, where they play important roles in the regulation of circadian vision. This review highlights some of the correlative studies of the circadian control of visual system functions in zebrafish. Because zebrafish maintain a high evolutionary proximity to mammals, the findings from zebrafish research may provide insights for a better understanding of the mechanisms of circadian vision in other vertebrate species including humans.
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Affiliation(s)
- Lei Li
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana
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Yang GY, Liu FY, Li X, Zhu QR, Chen BJ, Liu LQ. Decreased expression of gap junction delta-2 (GJD2) messenger RNA and connexin 36 protein in form-deprivation myopia of guinea pigs. Chin Med J (Engl) 2019; 132:1700-1705. [PMID: 31283648 PMCID: PMC6759107 DOI: 10.1097/cm9.0000000000000319] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND More than ten genome-wide association studies have identified the significant association between the gap junction delta-2 (GJD2) gene and myopia. However, no functional studies have been performed to confirm that this gene is correlated with myopia. This study aimed to observe how this gene changed in mRNA and protein level in the form-deprivation myopia (FDM) animal model. METHODS Four-week-old guinea pigs were randomly divided into two groups: control and FDM groups (n = 12 for each group). The right eyes of the FDM group were covered with opaque hemispherical plastic lenses for 3 weeks. For all the animals, refractive status, axial length (AL), and corneal radius of curvature were measured at baseline and 3 weeks later by streak retinoscope, A-scan ultrasonography, and keratometer, respectively. Retinal GJD2 mRNA expression and connexin 36 (Cx36) levels in FDM and control groups were measured by quantitative real-time PCR and Western blot analyses, respectively. Those results were compared using independent t test, Mann-Whitney U test, or paired t test. A significance level of P < 0.05 was used. RESULTS Three weeks later, the FDM group (form-deprived eyes) showed about a myopic shift of approximately -6.75 (-7.94 to -6.31) D, while the control group remained hyperopic with only a shift of -0.50 (-0.75 to 0.25) D (Z = -3.38, P < 0.01). The AL increased by 0.74 (0.61-0.76) and 0.10 (0.05-0.21) mm in FDM and control groups, respectively (Z = -3.37, P < 0.01). The relative mRNA expression of GJD2 in the FDM group decreased 31.58% more than the control group (t = 11.44, P < 0.01). The relative protein expression of CX36 on the retina was lowered by 37.72% in form-deprivation eyes as compared to the controls (t = 17.74, P < 0.01). CONCLUSION Both the mRNA expression of GJD2 and Cx36 protein amount were significantly decreased in the retina of FDM guinea pigs. This indicates that Cx36 is involved in FDM development, providing compensating evidence for the results obtained from genome-wide association studies.
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Affiliation(s)
- Guo-Yuan Yang
- Department of Opthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Feng-Yang Liu
- Department of Opthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
- Department of Ophthalmology, First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Xia Li
- Department of Opthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Qiu-Rong Zhu
- Department of Opthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Bing-Jie Chen
- Department of Opthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Long-Qian Liu
- Department of Opthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
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Increase in Mutual Information During Interaction with the Environment Contributes to Perception. ENTROPY 2019; 21:e21040365. [PMID: 33267079 PMCID: PMC7514849 DOI: 10.3390/e21040365] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/22/2019] [Accepted: 04/02/2019] [Indexed: 02/04/2023]
Abstract
Perception and motor interaction with physical surroundings can be analyzed by the changes in probability laws governing two possible outcomes of neuronal activity, namely the presence or absence of spikes (binary states). Perception and motor interaction with the physical environment are partly accounted for by a reduction in entropy within the probability distributions of binary states of neurons in distributed neural circuits, given the knowledge about the characteristics of stimuli in physical surroundings. This reduction in the total entropy of multiple pairs of circuits in networks, by an amount equal to the increase of mutual information, occurs as sensory information is processed successively from lower to higher cortical areas or between different areas at the same hierarchical level, but belonging to different networks. The increase in mutual information is partly accounted for by temporal coupling as well as synaptic connections as proposed by Bahmer and Gupta (Front. Neurosci. 2018). We propose that robust increases in mutual information, measuring the association between the characteristics of sensory inputs' and neural circuits' connectivity patterns, are partly responsible for perception and successful motor interactions with physical surroundings. The increase in mutual information, given the knowledge about environmental sensory stimuli and the type of motor response produced, is responsible for the coupling between action and perception. In addition, the processing of sensory inputs within neural circuits, with no prior knowledge of the occurrence of a sensory stimulus, increases Shannon information. Consequently, the increase in surprise serves to increase the evidence of the sensory model of physical surroundings.
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Papal S, Monti CE, Tennison ME, Swaroop A. Molecular dissection of cone photoreceptor-enriched genes encoding transmembrane and secretory proteins. J Neurosci Res 2018; 97:16-28. [PMID: 30260491 DOI: 10.1002/jnr.24329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 08/21/2018] [Accepted: 08/28/2018] [Indexed: 12/13/2022]
Abstract
Cone photoreceptors mediate color perception and daylight vision through intricate synaptic circuitry. In most mammalian retina, cones are greatly outnumbered by rods and exhibit inter-dependence for functional maintenance and survival. Currently, we have limited understanding of cone-specific molecular components that mediate response to extrinsic signaling factors or are involved in communication with rods and other retinal cells. To fulfill this gap, we compared the recently-published transcriptomes of developing S-cone-like photoreceptors from the Nrl-/- mouse retina with those of rods and identified candidate genes responsible for cone cell functions and communication. We generated an in silico expression profile of 823 genes that encode candidate transmembrane and secretory proteins and are up-regulated in Nrl-/- cone photoreceptors compared to wild type cones. In situ hybridization analysis validated high expression of seven of the selected candidate genes in the Nrl-/- retina. To examine their relevance to cone function, we performed in vivo knockdown of Epha10 in the Nrl-/- retina and demonstrated aberrant morphology and mislocalization of the photoreceptor cell bodies. Thus, the receptor tyrosine kinase Ephrin type-A receptor 10 appears to influence cone morphogenesis. Our studies reveal novel cone-enriched genes involved in interaction of cones with other retinal cell types and provide a framework for examining molecular pathways associated with intercellular communication.
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Affiliation(s)
- Samantha Papal
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Christopher E Monti
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Mackenzie E Tennison
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Anand Swaroop
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland
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28
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Abstract
We have long known that rod and cone signals interact within the retina and can even contribute to color vision, but the extent of these influences has remained unclear. New results with more powerful methods of RNA expression profiling, specific cell labeling, and single-cell recording have provided greater clarity and are showing that rod and cone signals can mix at virtually every level of signal processing. These interactions influence the integration of retinal signals and make an important contribution to visual perception.
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Affiliation(s)
- Gordon Fain
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California Los Angeles, 100 Stein Plaza, Los Angeles, CA 90095-7000, USA.,Department of Integrative Biology and Physiology, University of California Los Angeles, Terasaki Life Sciences, 610 Charles E. Young Drive South, Los Angeles, CA 90095-7239, USA
| | - Alapakkam P Sampath
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California Los Angeles, 100 Stein Plaza, Los Angeles, CA 90095-7000, USA
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Pérez Armendariz EM, Norcini M, Hernández-Tellez B, Castell-Rodríguez A, Coronel-Cruz C, Alquicira RG, Sideris A, Recio-Pinto E. Neurons and satellite glial cells in adult rat lumbar dorsal root ganglia express connexin 36. Acta Histochem 2018; 120:168-178. [PMID: 29224922 DOI: 10.1016/j.acthis.2017.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/02/2017] [Accepted: 11/15/2017] [Indexed: 01/08/2023]
Abstract
Previous studies have shown that following peripheral nerve injury there was a downregulation of the gap junction protein connexin 36 (Cx36) in the spinal cord; however, it is not known whether Cx36 protein is expressed in the dorsal root ganglia (DRGs), nor if its levels are altered following peripheral nerve injuries. Here we address these aspects in the adult rat lumbar DRG. Cx36 mRNA was detected using qRT-PCR, and Cx36 protein was identified in DRG sections using immunohistochemistry (IHC) and immunofluorescence (IF). Double staining revealed that Cx36 co-localizes with both anti-β-III tubulin, a neuronal marker, and anti-glutamine synthetase, a satellite glial cell (SGC) marker. In neurons, Cx36 staining was mostly uniform in somata and fibers of all sizes and its intensity increased at the cell membranes. This labeling pattern was in contrast with Cx36 IF dots mainly found at junctional membranes in islet beta cells used as a control tissue. Co-staining with anti-Cx43 and anti-Cx36 showed that whereas mostly uniform staining of Cx36 was found throughout neurons and SGCs, Cx43 IF puncta were localized to SGCs. Cx36 mRNA was expressed in normal lumbar DRG, and it was significantly down-regulated in L4 DRG of rats that underwent sciatic nerve injury resulting in persistent hypersensitivity. Collectively, these findings demonstrated that neurons and SGCs express Cx36 protein in normal DRG, and suggested that perturbation of Cx36 levels may contribute to chronic neuropathic pain resulting from a peripheral nerve injury.
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Affiliation(s)
- E Martha Pérez Armendariz
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Monica Norcini
- Department of Anesthesiology, NYULMC, 180 Varick Street, Room 677, New York, NY 10014, USA.
| | - Beatriz Hernández-Tellez
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Andrés Castell-Rodríguez
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Cristina Coronel-Cruz
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Raquel Guerrero Alquicira
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Alexandra Sideris
- Department of Anesthesiology, NYULMC, 180 Varick Street, Room 677, New York, NY 10014, USA.
| | - Esperanza Recio-Pinto
- Department of Anesthesiology, NYULMC, 180 Varick Street, Room 677, New York, NY 10014, USA; Departments of Anesthesiology, Biochemistry & Molecular Pharmacology, NYULMC, 180 Varick Street, Room 677, New York, NY 10014 USA.
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Suzuki DG, Grillner S. The stepwise development of the lamprey visual system and its evolutionary implications. Biol Rev Camb Philos Soc 2018; 93:1461-1477. [PMID: 29488315 DOI: 10.1111/brv.12403] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/29/2018] [Accepted: 02/05/2018] [Indexed: 01/11/2023]
Abstract
Lampreys, which represent the oldest group of living vertebrates (cyclostomes), show unique eye development. The lamprey larva has only eyespot-like immature eyes beneath a non-transparent skin, whereas after metamorphosis, the adult has well-developed image-forming camera eyes. To establish a functional visual system, well-organised visual centres as well as motor components (e.g. trunk muscles for locomotion) and interactions between them are needed. Here we review the available knowledge concerning the structure, function and development of the different parts of the lamprey visual system. The lamprey exhibits stepwise development of the visual system during its life cycle. In prolarvae and early larvae, the 'primary' retina does not have horizontal and amacrine cells, but does have photoreceptors, bipolar cells and ganglion cells. At this stage, the optic nerve projects mostly to the pretectum, where the dendrites of neurons in the nucleus of the medial longitudinal fasciculus (nMLF) appear to receive direct visual information and send motor outputs to the neck and trunk muscles. This simple neural circuit may generate negative phototaxis. Through the larval period, the lateral region of the retina grows again to form the 'secondary' retina and the topographic retinotectal projection of the optic nerve is formed, and at the same time, the extra-ocular muscles progressively develop. During metamorphosis, horizontal and amacrine cells differentiate for the first time, and the optic tectum expands and becomes laminated. The adult lamprey then has a sophisticated visual system for image-forming and visual decision-making. In the adult lamprey, the thalamic pathway (retina-thalamus-cortex/pallium) also transmits visual stimuli. Because the primary, simple light-detecting circuit in larval lamprey shares functional and developmental similarities with that of protochordates (amphioxus and tunicates), the visual development of the lamprey provides information regarding the evolutionary transition of the vertebrate visual system from the protochordate-type to the vertebrate-type.
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Affiliation(s)
- Daichi G Suzuki
- Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Sten Grillner
- Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
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