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Fitzpatrick MJ, Krizan J, Hsiang JC, Shen N, Kerschensteiner D. A pupillary contrast response in mice and humans: Neural mechanisms and visual functions. Neuron 2024; 112:2404-2422.e9. [PMID: 38697114 PMCID: PMC11257825 DOI: 10.1016/j.neuron.2024.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 12/21/2023] [Accepted: 04/10/2024] [Indexed: 05/04/2024]
Abstract
In the pupillary light response (PLR), increases in ambient light constrict the pupil to dampen increases in retinal illuminance. Here, we report that the pupillary reflex arc implements a second input-output transformation; it senses temporal contrast to enhance spatial contrast in the retinal image and increase visual acuity. The pupillary contrast response (PCoR) is driven by rod photoreceptors via type 6 bipolar cells and M1 ganglion cells. Temporal contrast is transformed into sustained pupil constriction by the M1's conversion of excitatory input into spike output. Computational modeling explains how the PCoR shapes retinal images. Pupil constriction improves acuity in gaze stabilization and predation in mice. Humans exhibit a PCoR with similar tuning properties to mice, which interacts with eye movements to optimize the statistics of the visual input for retinal encoding. Thus, we uncover a conserved component of active vision, its cell-type-specific pathway, computational mechanisms, and optical and behavioral significance.
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Affiliation(s)
- Michael J Fitzpatrick
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA; Medical Scientist Training Program, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Jenna Krizan
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Jen-Chun Hsiang
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Ning Shen
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Daniel Kerschensteiner
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA.
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2
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Tan B, Li H, Zhuo Y, Han L, Mupparapu R, Nanni D, Barathi VA, Palanker D, Schmetterer L, Ling T. Light-evoked deformations in rod photoreceptors, pigment epithelium and subretinal space revealed by prolonged and multilayered optoretinography. Nat Commun 2024; 15:5156. [PMID: 38898002 PMCID: PMC11186825 DOI: 10.1038/s41467-024-49014-5] [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: 11/21/2023] [Accepted: 05/21/2024] [Indexed: 06/21/2024] Open
Abstract
Phototransduction involves changes in concentration of ions and other solutes within photoreceptors and in subretinal space, which affect osmotic pressure and the associated water flow. Corresponding expansion and contraction of cellular layers can be imaged using optoretinography (ORG), based on phase-resolved optical coherence tomography (OCT). Until now, ORG could reliably detect only photoisomerization and phototransduction in photoreceptors, primarily in cones under bright stimuli. Here, by employing a phase-restoring subpixel motion correction algorithm, which enables imaging of the nanometer-scale tissue dynamics during minute-long recordings, and unsupervised learning of spatiotemporal patterns, we discover optical signatures of the other retinal structures' response to visual stimuli. These include inner and outer segments of rod photoreceptors, retinal pigment epithelium, and subretinal space in general. The high sensitivity of our technique enables detection of the retinal responses to dim stimuli: down to 0.01% bleach level, corresponding to natural levels of scotopic illumination. We also demonstrate that with a single flash, the optoretinogram can map retinal responses across a 12° field of view, potentially replacing multifocal electroretinography. This technique expands the diagnostic capabilities and practical applicability of optoretinography, providing an alternative to electroretinography, while combining structural and functional retinal imaging in the same OCT machine.
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Affiliation(s)
- Bingyao Tan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore
| | - Huakun Li
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore
| | - Yueming Zhuo
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Le Han
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore
| | - Rajeshkumar Mupparapu
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore
| | - Davide Nanni
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore
| | - Veluchamy Amutha Barathi
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore, Singapore
- Ophthalmology and Visual Sciences Academic Clinical Program (Eye ACP), Duke-NUS Medical School, Singapore, Singapore
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, 94305, USA.
- Department of Ophthalmology, Stanford University, Stanford, CA, 94305, USA.
| | - Leopold Schmetterer
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore.
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore.
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore, Singapore.
- Ophthalmology and Visual Sciences Academic Clinical Program (Eye ACP), Duke-NUS Medical School, Singapore, Singapore.
- Department of Ophthalmology, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland.
| | - Tong Ling
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore.
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore.
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore.
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3
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Biswas S, Shahriar S, Bachay G, Arvanitis P, Jamoul D, Brunken WJ, Agalliu D. Glutamatergic neuronal activity regulates angiogenesis and blood-retinal barrier maturation via Norrin/β-catenin signaling. Neuron 2024; 112:1978-1996.e6. [PMID: 38599212 PMCID: PMC11189759 DOI: 10.1016/j.neuron.2024.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 01/15/2024] [Accepted: 03/11/2024] [Indexed: 04/12/2024]
Abstract
Interactions among neuronal, glial, and vascular components are crucial for retinal angiogenesis and blood-retinal barrier (BRB) maturation. Although synaptic dysfunction precedes vascular abnormalities in many retinal pathologies, how neuronal activity, specifically glutamatergic activity, regulates retinal angiogenesis and BRB maturation remains unclear. Using in vivo genetic studies in mice, single-cell RNA sequencing (scRNA-seq), and functional validation, we show that deep plexus angiogenesis and paracellular BRB maturation are delayed in Vglut1-/- retinas where neurons fail to release glutamate. By contrast, deep plexus angiogenesis and paracellular BRB maturation are accelerated in Gnat1-/- retinas, where constitutively depolarized rods release excessive glutamate. Norrin expression and endothelial Norrin/β-catenin signaling are downregulated in Vglut1-/- retinas and upregulated in Gnat1-/- retinas. Pharmacological activation of endothelial Norrin/β-catenin signaling in Vglut1-/- retinas rescues defects in deep plexus angiogenesis and paracellular BRB maturation. Our findings demonstrate that glutamatergic neuronal activity regulates retinal angiogenesis and BRB maturation by modulating endothelial Norrin/β-catenin signaling.
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Affiliation(s)
- Saptarshi Biswas
- Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Sanjid Shahriar
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032, USA; Wyss Institute for Biologically Inspired Engineering, Boston, MA 02115, USA
| | - Galina Bachay
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Panos Arvanitis
- Warren Alpert Medical School, Brown University, Providence, RI 02903, USA
| | - Danny Jamoul
- Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA; John Jay College of Criminal Justice, City University of New York, New York, NY 10019, USA
| | - William J Brunken
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Dritan Agalliu
- Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032, USA.
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4
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Bassetto M, Kolesnikov AV, Lewandowski D, Kiser JZ, Halabi M, Einstein DE, Choi EH, Palczewski K, Kefalov VJ, Kiser PD. Dominant role for pigment epithelial CRALBP in supplying visual chromophore to photoreceptors. Cell Rep 2024; 43:114143. [PMID: 38676924 PMCID: PMC11211020 DOI: 10.1016/j.celrep.2024.114143] [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: 02/28/2024] [Revised: 03/22/2024] [Accepted: 04/09/2024] [Indexed: 04/29/2024] Open
Abstract
Cellular retinaldehyde-binding protein (CRALBP) supports production of 11-cis-retinaldehyde and its delivery to photoreceptors. It is found in the retinal pigment epithelium (RPE) and Müller glia (MG), but the relative functional importance of these two cellular pools is debated. Here, we report RPE- and MG-specific CRALBP knockout (KO) mice and examine their photoreceptor and visual cycle function. Bulk visual chromophore regeneration in RPE-KO mice is 15-fold slower than in controls, accounting for their delayed rod dark adaptation and protection against retinal phototoxicity, whereas MG-KO mice have normal bulk visual chromophore regeneration and retinal light damage susceptibility. Cone pigment regeneration is significantly impaired in RPE-KO mice but mildly affected in MG-KO mice, disclosing an unexpectedly strong reliance of cone photoreceptors on the RPE-based visual cycle. These data reveal a dominant role for RPE-CRALBP in supporting rod and cone function and highlight the importance of RPE cell targeting for CRALBP gene therapies.
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Affiliation(s)
- Marco Bassetto
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Research Service, Tibor Rubin VA Long Beach Medical Center, Long Beach, CA 90822, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Alexander V Kolesnikov
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Dominik Lewandowski
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Jianying Z Kiser
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Maximilian Halabi
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA
| | - David E Einstein
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Research Service, Tibor Rubin VA Long Beach Medical Center, Long Beach, CA 90822, USA
| | - Elliot H Choi
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Krzysztof Palczewski
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA; Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Vladimir J Kefalov
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Philip D Kiser
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Research Service, Tibor Rubin VA Long Beach Medical Center, Long Beach, CA 90822, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA; Department of Clinical Pharmacy Practice, University of California Irvine, Irvine, CA 92697, USA.
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5
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Chai Z, Ye Y, Silverman D, Rose K, Madura A, Reed RR, Chen J, Yau KW. Dark continuous noise from mutant G90D-rhodopsin predominantly underlies congenital stationary night blindness. Proc Natl Acad Sci U S A 2024; 121:e2404763121. [PMID: 38743626 PMCID: PMC11127052 DOI: 10.1073/pnas.2404763121] [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: 03/06/2024] [Accepted: 04/17/2024] [Indexed: 05/16/2024] Open
Abstract
Congenital stationary night blindness (CSNB) is an inherited retinal disease that causes a profound loss of rod sensitivity without severe retinal degeneration. One well-studied rhodopsin point mutant, G90D-Rho, is thought to cause CSNB because of its constitutive activity in darkness causing rod desensitization. However, the nature of this constitutive activity and its precise molecular source have not been resolved for almost 30 y. In this study, we made a knock-in (KI) mouse line with a very low expression of G90D-Rho (equal in amount to ~0.1% of normal rhodopsin, WT-Rho, in WT rods), with the remaining WT-Rho replaced by REY-Rho, a mutant with a very low efficiency of activating transducin due to a charge reversal of the highly conserved ERY motif to REY. We observed two kinds of constitutive noise: one being spontaneous isomerization (R*) of G90D-Rho at a molecular rate (R* s-1) 175-fold higher than WT-Rho and the other being G90D-Rho-generated dark continuous noise comprising low-amplitude unitary events occurring at a very high molecular rate equivalent in effect to ~40,000-fold of R* s-1 from WT-Rho. Neither noise type originated from G90D-Opsin because exogenous 11-cis-retinal had no effect. Extrapolating the above observations at low (0.1%) expression of G90D-Rho to normal disease exhibited by a KI mouse model with RhoG90D/WTand RhoG90D/G90D genotypes predicts the disease condition very well quantitatively. Overall, the continuous noise from G90D-Rho therefore predominates, constituting the major equivalent background light causing rod desensitization in CSNB.
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Affiliation(s)
- Zuying Chai
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Yaqing Ye
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Daniel Silverman
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD21205
- Biochemistry, Cellular and Molecular Biology Graduate Program, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Kasey Rose
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - Alana Madura
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - Randall R. Reed
- Department of Molecular Biology and Genetics (Emeritus), Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Jeannie Chen
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - King-Wai Yau
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD21205
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6
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Biswas S, Shahriar S, Bachay G, Arvanitis P, Jamoul D, Brunken WJ, Agalliu D. Glutamatergic neuronal activity regulates angiogenesis and blood-retinal barrier maturation via Norrin/β-catenin signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.10.548410. [PMID: 37503079 PMCID: PMC10369888 DOI: 10.1101/2023.07.10.548410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Interactions among neuronal, glial and vascular components are crucial for retinal angiogenesis and blood-retinal barrier (BRB) maturation. Although synaptic dysfunction precedes vascular abnormalities in many retinal pathologies, how neuronal activity, specifically glutamatergic activity, regulates retinal angiogenesis and BRB maturation remains unclear. Using in vivo genetic studies in mice, single-cell RNA-sequencing and functional validation, we show that deep plexus angiogenesis and paracellular BRB maturation are delayed in Vglut1 -/- retinas where neurons fail to release glutamate. In contrast, deep plexus angiogenesis and paracellular BRB maturation are accelerated in Gnat1 -/- retinas where constitutively depolarized rods release excessive glutamate. Norrin expression and endothelial Norrin/β-catenin signaling are downregulated in Vglut1 -/- retinas, and upregulated in Gnat1 -/- retinas. Pharmacological activation of endothelial Norrin/β-catenin signaling in Vglut1 -/- retinas rescued defects in deep plexus angiogenesis and paracellular BRB maturation. Our findings demonstrate that glutamatergic neuronal activity regulates retinal angiogenesis and BRB maturation by modulating endothelial Norrin/β-catenin signaling.
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7
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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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8
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Tworak A, Kolesnikov AV, Hong JD, Choi EH, Luu JC, Palczewska G, Dong Z, Lewandowski D, Brooks MJ, Campello L, Swaroop A, Kiser PD, Kefalov VJ, Palczewski K. Rapid RGR-dependent visual pigment recycling is mediated by the RPE and specialized Müller glia. Cell Rep 2023; 42:112982. [PMID: 37585292 PMCID: PMC10530494 DOI: 10.1016/j.celrep.2023.112982] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/14/2023] [Accepted: 07/29/2023] [Indexed: 08/18/2023] Open
Abstract
In daylight, demand for visual chromophore (11-cis-retinal) exceeds supply by the classical visual cycle. This shortfall is compensated, in part, by the retinal G-protein-coupled receptor (RGR) photoisomerase, which is expressed in both the retinal pigment epithelium (RPE) and in Müller cells. The relative contributions of these two cellular pools of RGR to the maintenance of photoreceptor light responses are not known. Here, we use a cell-specific gene reactivation approach to elucidate the kinetics of RGR-mediated recovery of photoreceptor responses following light exposure. Electroretinographic measurements in mice with RGR expression limited to either cell type reveal that the RPE and a specialized subset of Müller glia contribute both to scotopic and photopic function. We demonstrate that 11-cis-retinal formed through photoisomerization is rapidly hydrolyzed, consistent with its role in a rapid visual pigment regeneration process. Our study shows that RGR provides a pan-retinal sink for all-trans-retinal released under sustained light conditions and supports rapid chromophore regeneration through the photic visual cycle.
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Affiliation(s)
- Aleksander Tworak
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA.
| | - Alexander V Kolesnikov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - John D Hong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Jennings C Luu
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Grazyna Palczewska
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Polgenix, Inc., Department of Medical Devices, Cleveland, OH 44106, USA
| | - Zhiqian Dong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Dominik Lewandowski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Matthew J Brooks
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Laura Campello
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Philip D Kiser
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697, USA; Department of Clinical Pharmacy Practice, University of California, Irvine, Irvine, CA 92697, USA; Research Service, VA Long Beach Healthcare System, Long Beach, CA 90822, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697, USA; Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697, USA.
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9
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Moakedi F, Aljammal R, Poria D, Saravanan T, Rhodes SB, Reid C, Guan T, Kefalov VJ, Ramamurthy V. Prenylation is essential for the enrichment of cone phosphodiesterase-6 (PDE6) in outer segments and efficient cone phototransduction. Hum Mol Genet 2023; 32:2735-2750. [PMID: 37384398 PMCID: PMC10460490 DOI: 10.1093/hmg/ddad108] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/20/2023] [Accepted: 06/23/2023] [Indexed: 07/01/2023] Open
Abstract
Phosphodiesterase-6 (PDE6) is the key phototransduction effector enzyme residing in the outer segment (OS) of photoreceptors. Cone PDE6 is a tetrameric protein consisting of two inhibitory subunits (γ') and two catalytic subunits (α'). The catalytic subunit of cone PDE6 contains a C-terminus prenylation motif. Deletion of PDE6α' C-terminal prenylation motif is linked to achromatopsia (ACHM), a type of color blindness in humans. However, mechanisms behind the disease and roles for lipidation of cone PDE6 in vision are unknown. In this study, we generated two knock-in mouse models expressing mutant variants of cone PDE6α' lacking the prenylation motif (PDE6α'∆C). We find that the C-terminal prenylation motif is the primary determinant for the association of cone PDE6 protein with membranes. Cones from PDE6α'∆C homozygous mice are less sensitive to light, and their response to light is delayed, whereas cone function in heterozygous PDE6α'∆C/+ mice is unaffected. Surprisingly, the expression level and assembly of cone PDE6 protein were unaltered in the absence of prenylation. Unprenylated assembled cone PDE6 in PDE6α'∆C homozygous animals is mislocalized and enriched in the cone inner segment and synaptic terminal. Interestingly, the disk density and the overall length of cone OS in PDE6α'∆C homozygous mutants are altered, highlighting a novel structural role for PDE6 in maintaining cone OS length and morphology. The survival of cones in the ACHM model generated in this study bodes well for gene therapy as a treatment option for restoring vision in patients with similar mutations in the PDE6C gene.
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Affiliation(s)
- Faezeh Moakedi
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
- Department of Ophthalmology and Visual Sciences, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
| | - Rawaa Aljammal
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
- Department of Ophthalmology and Visual Sciences, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
| | - Deepak Poria
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697, USA
| | - Thamaraiselvi Saravanan
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
- Department of Ophthalmology and Visual Sciences, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
| | - Scott B Rhodes
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
- Department of Ophthalmology and Visual Sciences, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
| | - Chyanne Reid
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
- Department of Ophthalmology and Visual Sciences, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
| | - Tongju Guan
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
- Department of Ophthalmology and Visual Sciences, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697, USA
| | - Visvanathan Ramamurthy
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
- Department of Ophthalmology and Visual Sciences, School of Medicine, West Virginia University, Morgantown, WV 26506, USA
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10
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Todorova V, Stauffacher MF, Ravotto L, Nötzli S, Karademir D, Ebner LJA, Imsand C, Merolla L, Hauck SM, Samardzija M, Saab AS, Barros LF, Weber B, Grimm C. Deficits in mitochondrial TCA cycle and OXPHOS precede rod photoreceptor degeneration during chronic HIF activation. Mol Neurodegener 2023; 18:15. [PMID: 36882871 PMCID: PMC9990367 DOI: 10.1186/s13024-023-00602-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 02/03/2023] [Indexed: 03/09/2023] Open
Abstract
BACKGROUND Major retinal degenerative diseases, including age-related macular degeneration, diabetic retinopathy and retinal detachment, are associated with a local decrease in oxygen availability causing the formation of hypoxic areas affecting the photoreceptor (PR) cells. Here, we addressed the underlying pathological mechanisms of PR degeneration by focusing on energy metabolism during chronic activation of hypoxia-inducible factors (HIFs) in rod PR. METHODS We used two-photon laser scanning microscopy (TPLSM) of genetically encoded biosensors delivered by adeno-associated viruses (AAV) to determine lactate and glucose dynamics in PR and inner retinal cells. Retinal layer-specific proteomics, in situ enzymatic assays and immunofluorescence studies were used to analyse mitochondrial metabolism in rod PRs during chronic HIF activation. RESULTS PRs exhibited remarkably higher glycolytic flux through the hexokinases than neurons of the inner retina. Chronic HIF activation in rods did not cause overt change in glucose dynamics but an increase in lactate production nonetheless. Furthermore, dysregulation of the oxidative phosphorylation pathway (OXPHOS) and tricarboxylic acid (TCA) cycle in rods with an activated hypoxic response decelerated cellular anabolism causing shortening of rod photoreceptor outer segments (OS) before onset of cell degeneration. Interestingly, rods with deficient OXPHOS but an intact TCA cycle did not exhibit these early signs of anabolic dysregulation and showed a slower course of degeneration. CONCLUSION Together, these data indicate an exceeding high glycolytic flux in rods and highlight the importance of mitochondrial metabolism and especially of the TCA cycle for PR survival in conditions of increased HIF activity.
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Affiliation(s)
- Vyara Todorova
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Mia Fee Stauffacher
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Luca Ravotto
- Institute of Pharmacology and Toxicology and Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland
| | - Sarah Nötzli
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Duygu Karademir
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Lynn J A Ebner
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Cornelia Imsand
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Luca Merolla
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Stefanie M Hauck
- Metabolomics and Proteomics Core, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764, Munich, Germany
| | - Marijana Samardzija
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology and Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland
| | - L Felipe Barros
- Centro de Estudios Científicos (CECs), Valdivia, Chile.,Universidad San Sebastián, Valdivia, Chile
| | - Bruno Weber
- Institute of Pharmacology and Toxicology and Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland
| | - Christian Grimm
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland.
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11
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Cellular and Molecular Mechanisms of Pathogenesis Underlying Inherited Retinal Dystrophies. Biomolecules 2023; 13:biom13020271. [PMID: 36830640 PMCID: PMC9953031 DOI: 10.3390/biom13020271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/23/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
Inherited retinal dystrophies (IRDs) are congenital retinal degenerative diseases that have various inheritance patterns, including dominant, recessive, X-linked, and mitochondrial. These diseases are most often the result of defects in rod and/or cone photoreceptor and retinal pigment epithelium function, development, or both. The genes associated with these diseases, when mutated, produce altered protein products that have downstream effects in pathways critical to vision, including phototransduction, the visual cycle, photoreceptor development, cellular respiration, and retinal homeostasis. The aim of this manuscript is to provide a comprehensive review of the underlying molecular mechanisms of pathogenesis of IRDs by delving into many of the genes associated with IRD development, their protein products, and the pathways interrupted by genetic mutation.
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12
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Decoding transcriptional regulation via a human gene expression predictor. J Genet Genomics 2023; 50:305-317. [PMID: 36693565 DOI: 10.1016/j.jgg.2023.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 01/04/2023] [Accepted: 01/10/2023] [Indexed: 01/22/2023]
Abstract
Transcription factors (TFs) regulate cellular activities by controlling gene expression, but a predictive model describing how TFs quantitatively modulate human transcriptomes is lacking. We construct a universal human gene expression predictor and utilize it to decode transcriptional regulation. Using the expression of 1613 TFs, the predictor reconstitutes highly accurate transcriptomes for samples derived from a wide range of tissues and conditions. The broad applicability of the predictor indicates that it recapitulates the quantitative relationships between TFs and target genes ubiquitous across tissues. Significant interacting TF-target gene pairs are extracted from the predictor and enable downstream inference of TF regulators for diverse pathways involved in development, immunity, metabolism, and stress response. A detailed analysis of the hematopoiesis process reveals an atlas of key TFs regulating the development of different hematopoietic cell lineages, and a portion of these TFs are conserved between humans and mice. The results demonstrate that our method is capable of delineating the TFs responsible for fate determination. Compared to other existing tools, our approach shows better performance in recovering the correct TF regulators. Thus, we present a novel approach that can be used to study human transcriptional regulation in general.
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13
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Unusual phototransduction via cross-motif signaling from G q to adenylyl cyclase in intrinsically photosensitive retinalganglion cells. Proc Natl Acad Sci U S A 2023; 120:e2216599120. [PMID: 36584299 PMCID: PMC9910442 DOI: 10.1073/pnas.2216599120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Nonimage-forming vision in mammals is mediated primarily by melanopsin (OPN4)-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs). In mouse M1-ipRGCs, melanopsin predominantly activates, via Gαq,11,14, phospholipase C-β4 to open transient receptor 6 (TRPC6) and TRPC7 channels. In M2- and M4-ipRGCs, however, a prominent phototransduction mechanism involves the opening of hyperpolarization- and cyclic nucleotide-gated channels via cyclic nucleotide, although the upstream steps remain uncertain. We report here experiments, primarily on M4-ipRGCs, with photo-uncaging of cyclic nucleotides and virally expressed CNGA2 channels to conclude that the second messenger is cyclic adenosine monophosphate (cAMP) - very surprising considering that cyclic guanosine monophosphate (cGMP) is used in almost all cyclic nucleotide-mediated phototransduction mechanisms across the animal kingdom. We further found that the upstream G protein is likewise Gq, which via its Gβγ subunits directly activates adenylyl cyclase (AC). Our findings are a demonstration in a native cell of a cross-motif GPCR signaling pathway from Gq directly to AC with a specific function.
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14
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Hollingsworth TJ, Wang X, Simpson RN, White WA, Williams RW, Jablonski MM. Current Advancements in Mouse Models of Retinal Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:371-376. [PMID: 37440059 DOI: 10.1007/978-3-031-27681-1_54] [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
The field of retinal degenerative (RDs) disease study has been in a state of exponential growth from discovering the underlying genetic components of such diseases as age-related macular degeneration (AMD) and retinitis pigmentosa (RP) to the first gene therapy developed and approved for human Leber congenital amaurosis. However, a source for high-fidelity animal models of these complex, multifactorial, and/or polygenic diseases is a need that has yet to be fulfilled. While models for AMD and RP do exist, they often require aging the animals for a year or more, feeding special diets, or introduction of external modulators such as exposure to cigarette smoke. Currently, work is being done to uncover high-fidelity naturally occurring models of these retinal diseases with the hope and intent of providing the vision community the tools it needs to better understand, treat, and, one day, cure the patients suffering from these devastating afflictions.
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Affiliation(s)
- T J Hollingsworth
- Department of Ophthalmology, University of Tennessee Health Sciences Center, Memphis, TN, USA.
- Department of Medicine, University of Tennessee Health Sciences Center, Memphis, TN, USA.
- Hamilton Eye Institute, University of Tennessee Health Sciences Center, Memphis, TN, USA.
| | - Xiangdi Wang
- Department of Ophthalmology, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Department of Medicine, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Hamilton Eye Institute, University of Tennessee Health Sciences Center, Memphis, TN, USA
| | - Raven N Simpson
- Department of Ophthalmology, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Department of Medicine, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Hamilton Eye Institute, University of Tennessee Health Sciences Center, Memphis, TN, USA
| | - William A White
- Department of Ophthalmology, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Department of Medicine, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Hamilton Eye Institute, University of Tennessee Health Sciences Center, Memphis, TN, USA
| | - Robert W Williams
- Department of Medicine, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Hamilton Eye Institute, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Sciences Center, Memphis, TN, USA
| | - Monica M Jablonski
- Department of Ophthalmology, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Department of Medicine, University of Tennessee Health Sciences Center, Memphis, TN, USA
- Hamilton Eye Institute, University of Tennessee Health Sciences Center, Memphis, TN, USA
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15
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Adhikari RD, Kossoff AM, Cornwall MC, Makino CL. Bicarbonate boosts flash response amplitude to augment absolute sensitivity and extend dynamic range in murine retinal rods. Front Mol Neurosci 2023; 16:1125006. [PMID: 37122625 PMCID: PMC10140344 DOI: 10.3389/fnmol.2023.1125006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 03/15/2023] [Indexed: 05/02/2023] Open
Abstract
Rod photoreceptors in the retina adjust their responsiveness and sensitivity so that they can continue to provide meaningful information over a wide range of light intensities. By stimulating membrane guanylate cyclases in the outer segment to synthesize cGMP at a faster rate in a Ca2+-dependent fashion, bicarbonate increases the circulating "dark" current and accelerates flash response kinetics in amphibian rods. Compared to amphibian rods, mammalian rods are smaller in size, operate at a higher temperature, and express visual cascade proteins with somewhat different biochemical properties. Here, we evaluated the role of bicarbonate in rods of cpfl3 mice. These mice are deficient in their expression of functional cone transducin, Gnat2, making cones very insensitive to light, so the rod response to light could be observed in isolation in electroretinogram recordings. Bicarbonate increased the dark current and absolute sensitivity and quickened flash response recovery in mouse rods to a greater extent than in amphibian rods. In addition, bicarbonate enabled mouse rods to respond over a range that extended to dimmer flashes. Larger flash responses may have resulted in part from a bicarbonate-induced elevation in intracellular pH. However, high pH alone had little effect on flash response recovery kinetics and even suppressed the accelerating effect of bicarbonate, consistent with a direct, modulatory action of bicarbonate on Ca2+- dependent, membrane guanylate cyclase activity.
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16
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Flood MD, Veloz HLB, Hattar S, Carvalho-de-Souza JL. Robust visual cortex evoked potentials (VEP) in Gnat1 and Gnat2 knockout mice. Front Cell Neurosci 2022; 16:1090037. [PMID: 36605613 PMCID: PMC9807669 DOI: 10.3389/fncel.2022.1090037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin, imparting to themselves the ability to respond to light in the absence of input from rod or cone photoreceptors. Since their discovery ipRGCs have been found to play a significant role in non-image-forming aspects of vision, including circadian photoentrainment, neuroendocrine regulation, and pupillary control. In the past decade it has become increasingly clear that some ipRGCs also contribute directly to pattern-forming vision, the ability to discriminate shapes and objects. However, the degree to which melanopsin-mediated phototransduction, versus that of rods and cones, contributes to this function is still largely unknown. Earlier attempts to quantify this contribution have relied on genetic knockout models that target key phototransductive proteins in rod and cone photoreceptors, ideally to isolate melanopsin-mediated responses. In this study we used the Gnat1-/-; Gnat2cpfl3/cpfl3 mouse model, which have global knockouts for the rod and cone α-transducin proteins. These genetic modifications completely abolish rod and cone photoresponses under light-adapted conditions, locking these cells into a "dark" state. We recorded visually evoked potentials in these animals and found that they still showed robust light responses, albeit with reduced light sensitivity, with similar magnitudes to control mice. These responses had characteristics that were in line with a melanopsin-mediated signal, including delayed kinetics and increased saturability. Additionally, we recorded electroretinograms in a sub-sample of these mice and were unable to find any characteristic waveform related the activation of photoreceptors or second-order retinal neurons, suggesting ipRGCs as the origin of light responses. Our results show a profound ability for melanopsin phototransduction to directly contribute to the primary pattern-forming visual pathway.
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Affiliation(s)
- Michael D. Flood
- Department of Anesthesiology, College of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Hannah L. B. Veloz
- Department of Anesthesiology, College of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Samer Hattar
- Section on Light and Circadian Rhythms (SLCR), National Institute of Mental Health, Bethesda, MD, United States
| | - Joao L. Carvalho-de-Souza
- Department of Anesthesiology, College of Medicine, The University of Arizona, Tucson, AZ, United States,Department of Physiology, College of Medicine, The University of Arizona, Tucson, AZ, United States,Department of Ophthalmology and Vision Science, College of Medicine, The University of Arizona, Tucson, AZ, United States,BIO5 Institute, The University of Arizona, Tucson, AZ, United States,*Correspondence: Joao L. Carvalho-de-Souza,
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17
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Berkowitz BA, Podolsky RH, Childers KL, Roberts R, Katz R, Waseem R, Robbings BM, Hass DT, Hurley JB, Sweet IR, Goodman C, Qian H, Alvisio B, Heaps S. Transducin-Deficient Rod Photoreceptors Evaluated With Optical Coherence Tomography and Oxygen Consumption Rate Energy Biomarkers. Invest Ophthalmol Vis Sci 2022; 63:22. [PMID: 36576748 PMCID: PMC9804021 DOI: 10.1167/iovs.63.13.22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Purpose To test the hypothesis that rod energy biomarkers in light and dark are similar in mice without functional rod transducin (Gnat1rd17). Methods Gnat1rd17 and wildtype (WT) mice were studied in canonically low energy demand (light) and high energy demand (dark) conditions. We measured rod inner segment ellipsoid zone (ISez) profile shape, external limiting membrane-retinal pigment epithelium (ELM-RPE) thickness, and magnitude of a hyporeflective band (HB) intensity dip located between photoreceptor tips and apical RPE; antioxidants were given in a subset of mice. Oxygen consumption rate (OCR) and visual performance indexes were also measured. Results The lower energy demand expected in light-adapted wildtype retinas was associated with an elongated ISez, thicker ELM-RPE, and higher HB magnitude, and lower OCR compared to high energy demand conditions in the dark. Gnat1rd17 mice showed a wildtype-like ISez profile shape at 20 minutes of light that became rounder at 60 minutes; at both times, ELM-RPE was smaller than wildtype values, and the HB magnitude was unmeasurable. OCR was higher than in the dark. Light-adapted Gnat1rd17 mice biomarkers were unaffected by anti-oxidants. Gnat1rd17 mice showed modest outer nuclear layer thinning and no reduction in visual performance indexes. Conclusions Light-stimulated changes in all biomarkers in WT mice are consistent with the established light-induced decrease in net energy demand. In contrast, biomarker changes in Gnat1rd17 mice raise the possibility that light increases net energy demand in the absence of rod phototransduction.
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Affiliation(s)
- Bruce A Berkowitz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Robert H Podolsky
- Biostatistics and Study Methodology, Children's National Hospital, Silver Spring, Maryland, United States
| | - Karen Lins Childers
- Beaumont Research Institute, Beaumont Health, Royal Oak, Michigan, United States
| | - Robin Roberts
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Ryan Katz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Rida Waseem
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Brian M Robbings
- Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington, United States.,Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, United States
| | - Daniel T Hass
- Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - James B Hurley
- Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - Ian R Sweet
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, United States
| | - Cole Goodman
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Bruno Alvisio
- OSIO Bioinformatics Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Sam Heaps
- OSIO Bioinformatics Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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18
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Melanopsin retinal ganglion cells mediate light-promoted brain development. Cell 2022; 185:3124-3137.e15. [PMID: 35944541 DOI: 10.1016/j.cell.2022.07.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 05/10/2022] [Accepted: 07/15/2022] [Indexed: 02/05/2023]
Abstract
During development, melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) become light sensitive much earlier than rods and cones. IpRGCs project to many subcortical areas, whereas physiological functions of these projections are yet to be fully elucidated. Here, we found that ipRGC-mediated light sensation promotes synaptogenesis of pyramidal neurons in various cortices and the hippocampus. This phenomenon depends on activation of ipRGCs and is mediated by the release of oxytocin from the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) into cerebral-spinal fluid. We further characterized a direct connection between ipRGCs and oxytocin neurons in the SON and mutual projections between oxytocin neurons in the SON and PVN. Moreover, we showed that the lack of ipRGC-mediated, light-promoted early cortical synaptogenesis compromised learning ability in adult mice. Our results highlight the importance of light sensation early in life on the development of learning ability and therefore call attention to suitable light environment for infant care.
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19
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Kolesnikov AV, Luu J, Jin H, Palczewski K, Kefalov VJ. Deletion of Protein Phosphatase 2A Accelerates Retinal Degeneration in GRK1- and Arr1-Deficient Mice. Invest Ophthalmol Vis Sci 2022; 63:18. [PMID: 35861670 PMCID: PMC9315073 DOI: 10.1167/iovs.63.8.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Light detection in retinal rod photoreceptors is initiated by activation of the visual pigment rhodopsin. A critical, yet often-overlooked, step enabling efficient perception of light is rhodopsin dephosphorylation mediated by protein phosphatase 2A (PP2A). PP2A deficiency has been reported to impair rhodopsin regeneration after phosphorylation by G protein receptor kinase 1 (GRK1) and binding of arrestin (Arr1), thereby delaying rod dark adaptation. However, its effects on the viability of photoreceptors in the absence of GRK1 and Arr1 remain unclear. Here, we investigated the effects of PP2A deficiency in the absence of GRK1 or Arr1, both of which have been implicated in Oguchi disease, a form of night blindness. Methods Rod-specific mice lacking the predominant catalytic Cα-subunit of PP2A were crossed with the Grk1−/− or Arr1−/− strains to obtain double knockout lines. Rod photoreceptor viability was analyzed in histological cross-sections of the retina stained with hematoxylin and eosin, and rod function was evaluated by ex vivo electroretinography. Results PP2A deficiency alone did not impair photoreceptor viability up to 12 months of age. Retinal degeneration was more pronounced in rods lacking GRK1 compared to rods lacking Arr1, and degeneration was accelerated in both Grk1−/− or Arr1−/− strains where PP2A was also deleted. In Arr1−/− mice, rod maximal photoresponse amplitudes were reduced by 80% at 3 months, and this diminution was enhanced further with concomitant PP2A deficiency. Conclusions These results suggest that although PP2A is not required for the survival of rods, its deletion accelerates the degeneration induced by the absence of either GRK1 or Arr1.
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Affiliation(s)
- Alexander V Kolesnikov
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, United States
| | - Jennings Luu
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, United States.,Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Hui Jin
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, United States.,Department of Physiology & Biophysics, University of California, Irvine, California, United States.,Department of Chemistry, University of California, Irvine, California, United States.,Department of Molecular Biology and Biochemistry, University of California, Irvine, California, United States
| | - Vladimir J Kefalov
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, United States.,Department of Physiology & Biophysics, University of California, Irvine, California, United States
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20
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Abbas F, Becker S, Jones BW, Mure LS, Panda S, Hanneken A, Vinberg F. Revival of light signalling in the postmortem mouse and human retina. Nature 2022; 606:351-357. [PMID: 35545677 PMCID: PMC10000337 DOI: 10.1038/s41586-022-04709-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 03/31/2022] [Indexed: 12/21/2022]
Abstract
Death is defined as the irreversible cessation of circulatory, respiratory or brain activity. Many peripheral human organs can be transplanted from deceased donors using protocols to optimize viability. However, tissues from the central nervous system rapidly lose viability after circulation ceases1,2, impeding their potential for transplantation. The time course and mechanisms causing neuronal death and the potential for revival remain poorly defined. Here, using the retina as a model of the central nervous system, we systemically examine the kinetics of death and neuronal revival. We demonstrate the swift decline of neuronal signalling and identify conditions for reviving synchronous in vivo-like trans-synaptic transmission in postmortem mouse and human retina. We measure light-evoked responses in human macular photoreceptors in eyes removed up to 5 h after death and identify modifiable factors that drive reversible and irreversible loss of light signalling after death. Finally, we quantify the rate-limiting deactivation reaction of phototransduction, a model G protein signalling cascade, in peripheral and macular human and macaque retina. Our approach will have broad applications and impact by enabling transformative studies in the human central nervous system, raising questions about the irreversibility of neuronal cell death, and providing new avenues for visual rehabilitation.
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Affiliation(s)
- Fatima Abbas
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Silke Becker
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Bryan W Jones
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Ludovic S Mure
- Salk Institute for Biological Studies, La Jolla, CA, USA.,Institute of Physiology, University of Bern, Bern, Switzerland.,Department of Neurology, Zentrum für Experimentelle Neurologie, Inselspital University Hospital Bern, Bern, Switzerland
| | | | - Anne Hanneken
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA. .,Retina Consultants San Diego, La Jolla, CA, USA.
| | - Frans Vinberg
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA.
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21
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In vivo base editing rescues cone photoreceptors in a mouse model of early-onset inherited retinal degeneration. Nat Commun 2022; 13:1830. [PMID: 35383196 PMCID: PMC8983734 DOI: 10.1038/s41467-022-29490-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 03/17/2022] [Indexed: 12/17/2022] Open
Abstract
Leber congenital amaurosis (LCA) is the most common cause of inherited retinal degeneration in children. LCA patients with RPE65 mutations show accelerated cone photoreceptor dysfunction and death, resulting in early visual impairment. It is therefore crucial to develop a robust therapy that not only compensates for lost RPE65 function but also protects photoreceptors from further degeneration. Here, we show that in vivo correction of an Rpe65 mutation by adenine base editor (ABE) prolongs the survival of cones in an LCA mouse model. In vitro screening of ABEs and sgRNAs enables the identification of a variant that enhances in vivo correction efficiency. Subretinal delivery of ABE and sgRNA corrects up to 40% of Rpe65 transcripts, restores cone-mediated visual function, and preserves cones in LCA mice. Single-cell RNA-seq reveals upregulation of genes associated with cone phototransduction and survival. Our findings demonstrate base editing as a potential gene therapy that confers long-lasting retinal protection. Leber congenital amaurosis is caused by mutations in RPE65 and leads to retinal degeneration in children. Here, the authors show that in vivo base editing can prolong the survival of cone photoreceptors and rescue their function in a mouse model of the disease.
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22
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Jin N, Tian LM, Fahrenfort I, Zhang Z, Postma F, Paul DL, Massey SC, Ribelayga CP. Genetic elimination of rod/cone coupling reveals the contribution of the secondary rod pathway to the retinal output. SCIENCE ADVANCES 2022; 8:eabm4491. [PMID: 35363529 PMCID: PMC10938630 DOI: 10.1126/sciadv.abm4491] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 02/10/2022] [Indexed: 06/14/2023]
Abstract
In the retina, signals originating from rod and cone photoreceptors can reach retinal ganglion cells (RGCs)-the output neurons-through different pathways. However, little is known about the exact sensitivities and operating ranges of these pathways. Previously, we created rod- or cone-specific Cx36 knockout (KO) mouse lines. Both lines are deficient in rod/cone electrical coupling and therefore provide a way to selectively remove the secondary rod pathway. We measured the threshold of the primary rod pathway in RGCs of wild-type mice. Under pharmacological blockade of the primary rod pathway, the threshold was elevated. This secondary component was removed in the Cx36 KOs to unmask the threshold of the third rod pathway, still below cone threshold. In turn, the cone threshold was estimated by several independent methods. Our work defines the functionality of the secondary rod pathway and describes an additive contribution of the different pathways to the retinal output.
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Affiliation(s)
- Nange Jin
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, USA
| | - Lian-Ming Tian
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, USA
| | - Iris Fahrenfort
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, USA
| | - Zhijing Zhang
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), 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, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, USA
- Elizabeth Morford Distinguished Chair in Ophthalmology and Research Director, Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, USA
| | - Christophe P. Ribelayga
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, USA
- Bernice Weingarten Chair in Ophthalmology, Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX, USA
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23
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Kaladchibachi S, Negelspach DC, Zeitzer JM, Fernandez FX. Investigation of the aging clock's intermittent-light responses uncovers selective deficits to green millisecond flashes. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 228:112389. [PMID: 35086027 DOI: 10.1016/j.jphotobiol.2022.112389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
The central pacemaker of flies, rodents, and humans generates less robust circadian output signals across normative aging. It is not well understood how changes in light sensitivity might contribute to this phenomenon. In the present study, we summarize results from an extended data series (n = 5681) showing that the locomotor activity rhythm of aged Drosophila can phase-shift normally to intermittently spaced episodes of bright polychromatic light exposure (600 lx) but that deficits emerge in response to 8, 16, and 120-millisecond flashes of narrowband blue (λm, 452 nm) and green (λm, 525 nm) LED light. For blue, phase-resetting of the activity rhythm of older flies is not as energy efficient as it is in younger flies at the fastest flash-exposures tested (8 milliseconds), suggesting there might be different floors of light duration necessary to incur photohabituation in each age group. For green, the responses of older flies are universally crippled relative to those of younger flies across the slate of protocols we tested. The difference in green flash photosensitivity is one of the most salient age-related phenotypes that has been documented in the circadian phase-shifting literature thus far. These data provide further impetus for investigations on pacemaker aging and how it might relate to changes in the circadian system's responses to particular sequences of light exposure tuned for wavelength, intensity, duration, and tempo.
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Affiliation(s)
| | | | - Jamie M Zeitzer
- Department of Psychiatry and Behavioral Sciences and Stanford Center for Sleep Sciences and Medicine, Stanford University, Stanford, CA, USA; Mental Illness Research, Education and Clinical Center, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - Fabian-Xosé Fernandez
- Department of Psychology, University of Arizona, Tucson, AZ, USA; Department of Neurology, University of Arizona, Tucson, AZ, USA; BIO5 and McKnight Brain Research Institutes, University of Arizona, Tucson, AZ, USA.
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24
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Poria D, Sun C, Santeford A, Kielar M, Apte RS, Kisselev OG, Chen S, Kefalov VJ. EML1 is essential for retinal photoreceptor migration and survival. Sci Rep 2022; 12:2897. [PMID: 35190581 PMCID: PMC8861151 DOI: 10.1038/s41598-022-06571-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 01/21/2022] [Indexed: 11/24/2022] Open
Abstract
Calcium regulates the response sensitivity, kinetics and adaptation in photoreceptors. In striped bass cones, this calcium feedback includes direct modulation of the transduction cyclic nucleotide-gated (CNG) channels by the calcium-binding protein CNG-modulin. However, the possible role of EML1, the mammalian homolog of CNG-modulin, in modulating phototransduction in mammalian photoreceptors has not been examined. Here, we used mice expressing mutant Eml1 to investigate its role in the development and function of mouse photoreceptors using immunostaining, in-vivo and ex-vivo retinal recordings, and single-cell suction recordings. We found that the mutation of Eml1 causes significant changes in the mouse retinal structure characterized by mislocalization of rods and cones in the inner retina. Consistent with the fraction of mislocalized photoreceptors, rod and cone-driven retina responses were reduced in the mutants. However, the Eml1 mutation had no effect on the dark-adapted responses of rods in the outer nuclear layer. Notably, we observed no changes in the cone sensitivity in the Eml1 mutant animals, either in darkness or during light adaptation, ruling out a role for EML1 in modulating cone CNG channels. Together, our results suggest that EML1 plays an important role in retina development but does not modulate phototransduction in mammalian rods and cones.
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Affiliation(s)
- Deepak Poria
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave, Box 8096, Saint Louis, MO, 63110, USA
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, 2121 Gillespie|837 Health Sciences Rd, Irvine, CA, 92697, USA
| | - Chi Sun
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave, Box 8096, Saint Louis, MO, 63110, USA
| | - Andrea Santeford
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave, Box 8096, Saint Louis, MO, 63110, USA
| | - Michel Kielar
- Unité Facultaire d'anatomie et de morphologie, Lausanne University Hospital, Lausanne, Switzerland
| | - Rajendra S Apte
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave, Box 8096, Saint Louis, MO, 63110, USA
- Department of Developmental Biology, Washington University in St. Louis School of Medicine, Saint Louis, MO, USA
- Department of Medicine, Washington University in St. Louis School of Medicine, Saint Louis, MO, USA
| | - Oleg G Kisselev
- Department of Ophthalmology, Saint Louis University School of Medicine, Saint Louis, MO, USA
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, MO, USA
| | - Shimming Chen
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave, Box 8096, Saint Louis, MO, 63110, USA.
- Department of Developmental Biology, Washington University in St. Louis School of Medicine, Saint Louis, MO, USA.
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave, Box 8096, Saint Louis, MO, 63110, USA.
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, 2121 Gillespie|837 Health Sciences Rd, Irvine, CA, 92697, USA.
- Department of Physiology and Biophysics, University of California, Irvine, CA, USA.
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25
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Schoonderwoerd RA, Buck TM, Andriessen CA, Wijnholds J, Hattar S, Meijer JH, Deboer T. Sleep Deprivation Does not Change the Flash Electroretinogram in Wild-type and Opn4-/-Gnat1-/- Mice. J Biol Rhythms 2022; 37:216-221. [PMID: 35132885 PMCID: PMC9008555 DOI: 10.1177/07487304221074995] [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] [Indexed: 11/23/2022]
Abstract
Sleep deprivation reduces the response of neuronal activity in the suprachiasmatic nucleus (SCN) and the phase shift in circadian behaviour to phase shifting light pulses, and thus seems to impair the adaptation of the circadian clock to the external light-dark cycle. The question remains where in the pathway of light input to the SCN the response is reduced. We therefore investigated whether the electroretinogram (ERG) changes after sleep deprivation in wild-type mice and in Opn4−/−Gnat1−/− mutant male mice. We found that the ERG is clearly affected by the Opn4−/−Gnat1−/− mutations, but that the ERG after sleep deprivation does not differ from the baseline response. The difference between wild-type and mutant is in accordance with the lack of functional rod and melanopsin in the retina of the mutant mice. We conclude that the decrease in light responsiveness of the SCN after sleep deprivation is probably not caused by changes at the retinal level, but rather at the postsynaptic site within the SCN, reflecting affected neurotransmitter signalling.
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Affiliation(s)
- Robin A Schoonderwoerd
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Thilo M Buck
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Samer Hattar
- Section of Light and Circadian Rhythms, National Institutes of Health, Bethesda, Maryland, USA
| | - Johanna H Meijer
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Tom Deboer
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
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26
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Stofkova A, Zloh M, Andreanska D, Fiserova I, Kubovciak J, Hejda J, Kutilek P, Murakami M. Depletion of Retinal Dopaminergic Activity in a Mouse Model of Rod Dysfunction Exacerbates Experimental Autoimmune Uveoretinitis: A Role for the Gateway Reflex. Int J Mol Sci 2021; 23:ijms23010453. [PMID: 35008877 PMCID: PMC8745287 DOI: 10.3390/ijms23010453] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/24/2021] [Accepted: 12/29/2021] [Indexed: 12/20/2022] Open
Abstract
The gateway reflex is a mechanism by which neural inputs regulate chemokine expression at endothelial cell barriers, thereby establishing gateways for the invasion of autoreactive T cells into barrier-protected tissues. In this study, we hypothesized that rod photoreceptor dysfunction causes remodeling of retinal neural activity, which influences the blood–retinal barrier and the development of retinal inflammation. We evaluated this hypothesis using Gnat1rd17 mice, a model of night blindness with late-onset rod-cone dystrophy, and experimental autoimmune uveoretinitis (EAU). Retinal remodeling and its effect on EAU development were investigated by transcriptome profiling, target identification, and functional validation. We showed that Gnat1rd17 mice primarily underwent alterations in their retinal dopaminergic system, triggering the development of an exacerbated EAU, which was counteracted by dopamine replacement with L-DOPA administered either systemically or locally. Remarkably, dopamine acted on retinal endothelial cells to inhibit NF-κB and STAT3 activity and the expression of downstream target genes such as chemokines involved in T cell recruitment. These results suggest that rod-mediated dopamine release functions in a gateway reflex manner in the homeostatic control of immune cell entry into the retina, and the loss of retinal dopaminergic activity in conditions associated with rod dysfunction increases the susceptibility to autoimmune uveitis.
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Affiliation(s)
- Andrea Stofkova
- Department of Physiology, Third Faculty of Medicine, Charles University, Ke Karlovu 4, 120 00 Prague, Czech Republic; (M.Z.); (D.A.); (I.F.)
- Correspondence: ; Tel.: +420-224-902-718
| | - Miloslav Zloh
- Department of Physiology, Third Faculty of Medicine, Charles University, Ke Karlovu 4, 120 00 Prague, Czech Republic; (M.Z.); (D.A.); (I.F.)
| | - Dominika Andreanska
- Department of Physiology, Third Faculty of Medicine, Charles University, Ke Karlovu 4, 120 00 Prague, Czech Republic; (M.Z.); (D.A.); (I.F.)
| | - Ivana Fiserova
- Department of Physiology, Third Faculty of Medicine, Charles University, Ke Karlovu 4, 120 00 Prague, Czech Republic; (M.Z.); (D.A.); (I.F.)
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic
| | - Jan Kubovciak
- Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic;
| | - Jan Hejda
- Department of Health Care and Population Protection, Faculty of Biomedical Engineering, Czech Technical University in Prague, Sitna Sq. 3105, 272 01 Kladno, Czech Republic; (J.H.); (P.K.)
| | - Patrik Kutilek
- Department of Health Care and Population Protection, Faculty of Biomedical Engineering, Czech Technical University in Prague, Sitna Sq. 3105, 272 01 Kladno, Czech Republic; (J.H.); (P.K.)
| | - Masaaki Murakami
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine and Graduate School of Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan;
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27
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Kalargyrou AA, Basche M, Hare A, West EL, Smith AJ, Ali RR, Pearson RA. Nanotube-like processes facilitate material transfer between photoreceptors. EMBO Rep 2021; 22:e53732. [PMID: 34494703 PMCID: PMC8567251 DOI: 10.15252/embr.202153732] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/16/2021] [Accepted: 08/20/2021] [Indexed: 12/12/2022] Open
Abstract
Neuronal communication is typically mediated via synapses and gap junctions. New forms of intercellular communication, including nanotubes (NTs) and extracellular vesicles (EVs), have been described for non-neuronal cells, but their role in neuronal communication is not known. Recently, transfer of cytoplasmic material between donor and host neurons ("material transfer") was shown to occur after photoreceptor transplantation. The cellular mechanism(s) underlying this surprising finding are unknown. Here, using transplantation, primary neuronal cultures and the generation of chimeric retinae, we show for the first time that mammalian photoreceptor neurons can form open-end NT-like processes. These processes permit the transfer of cytoplasmic and membrane-bound molecules in culture and after transplantation and can mediate gain-of-function in the acceptor cells. Rarely, organelles were also observed to transfer. Strikingly, use of chimeric retinae revealed that material transfer can occur between photoreceptors in the intact adult retina. Conversely, while photoreceptors are capable of releasing EVs, at least in culture, these are taken up by glia and not by retinal neurons. Our findings provide the first evidence of functional NT-like processes forming between sensory neurons in culture and in vivo.
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Affiliation(s)
- Aikaterini A Kalargyrou
- University College London Institute of OphthalmologyLondonUK
- Centre for Cell and Gene TherapyKing’s College LondonGuy’s HospitalLondonUK
| | - Mark Basche
- University College London Institute of OphthalmologyLondonUK
- Centre for Cell and Gene TherapyKing’s College LondonGuy’s HospitalLondonUK
| | - Aura Hare
- University College London Institute of OphthalmologyLondonUK
- Centre for Cell and Gene TherapyKing’s College LondonGuy’s HospitalLondonUK
| | - Emma L West
- University College London Institute of OphthalmologyLondonUK
- Centre for Cell and Gene TherapyKing’s College LondonGuy’s HospitalLondonUK
| | - Alexander J Smith
- University College London Institute of OphthalmologyLondonUK
- Centre for Cell and Gene TherapyKing’s College LondonGuy’s HospitalLondonUK
| | - Robin R Ali
- University College London Institute of OphthalmologyLondonUK
- Centre for Cell and Gene TherapyKing’s College LondonGuy’s HospitalLondonUK
- Kellogg Eye CenterUniversity of MichiganAnn ArborMIUSA
| | - Rachael A Pearson
- University College London Institute of OphthalmologyLondonUK
- Centre for Cell and Gene TherapyKing’s College LondonGuy’s HospitalLondonUK
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28
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Klaus C, Caruso G, Gurevich VV, Hamm HE, Makino CL, DiBenedetto E. Phototransduction in retinal cones: Analysis of parameter importance. PLoS One 2021; 16:e0258721. [PMID: 34710119 PMCID: PMC8553137 DOI: 10.1371/journal.pone.0258721] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 10/05/2021] [Indexed: 12/26/2022] Open
Abstract
In daylight, cone photoreceptors in the retina are responsible for the bulk of visual perception, yet compared to rods, far less is known quantitatively about their biochemistry. This is partly because it is hard to isolate and purify cone proteins. The issue is also complicated by the synergistic interaction of these parameters in producing systems biology outputs, such as photoresponse. Using a 3-D resolved, finite element model of cone outer segments, here we conducted a study of parameter significance using global sensitivity analysis, by Sobol indices, which was contextualized within the uncertainty surrounding these parameters in the available literature. The analysis showed that a subset of the parameters influencing the circulating dark current, such as the turnover rate of cGMP in the dark, may be most influential for variance with experimental flash response, while the shut-off rates of photoexcited rhodopsin and phosphodiesterase also exerted sizable effect. The activation rate of transducin by rhodopsin and the light-induced hydrolysis rate of cGMP exerted measurable effects as well but were estimated as relatively less significant. The results of this study depend on experimental ranges currently described in the literature and should be revised as these become better established. To that end, these findings may be used to prioritize parameters for measurement in future investigations.
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Affiliation(s)
- Colin Klaus
- The Mathematical Biosciences Institute, The Ohio State University, Columbus, Ohio, United States of America
| | - Giovanni Caruso
- CNR, Ist. Tecnologie Applicate ai Beni Culturali, Rome, Italy
| | - Vsevolod V. Gurevich
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Heidi E. Hamm
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Clint L. Makino
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, United States of America
| | - Emmanuele DiBenedetto
- Department of Mathematics, Vanderbilt University, Nashville, TN, United States of America
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29
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Kiser PD. Retinal pigment epithelium 65 kDa protein (RPE65): An update. Prog Retin Eye Res 2021; 88:101013. [PMID: 34607013 PMCID: PMC8975950 DOI: 10.1016/j.preteyeres.2021.101013] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/21/2021] [Accepted: 09/24/2021] [Indexed: 12/21/2022]
Abstract
Vertebrate vision critically depends on an 11-cis-retinoid renewal system known as the visual cycle. At the heart of this metabolic pathway is an enzyme known as retinal pigment epithelium 65 kDa protein (RPE65), which catalyzes an unusual, possibly biochemically unique, reaction consisting of a coupled all-trans-retinyl ester hydrolysis and alkene geometric isomerization to produce 11-cis-retinol. Early work on this isomerohydrolase demonstrated its membership to the carotenoid cleavage dioxygenase superfamily and its essentiality for 11-cis-retinal production in the vertebrate retina. Three independent studies published in 2005 established RPE65 as the actual isomerohydrolase instead of a retinoid-binding protein as previously believed. Since the last devoted review of RPE65 enzymology appeared in this journal, major advances have been made in a number of areas including our understanding of the mechanistic details of RPE65 isomerohydrolase activity, its phylogenetic origins, the relationship of its membrane binding affinity to its catalytic activity, its role in visual chromophore production for rods and cones, its modulation by macromolecules and small molecules, and the involvement of RPE65 mutations in the development of retinal diseases. In this article, I will review these areas of progress with the goal of integrating results from the varied experimental approaches to provide a comprehensive picture of RPE65 biochemistry. Key outstanding questions that may prove to be fruitful future research pursuits will also be highlighted.
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Affiliation(s)
- Philip D Kiser
- Research Service, VA Long Beach Healthcare System, Long Beach, CA, 90822, USA; Department of Physiology & Biophysics, University of California, Irvine School of Medicine, Irvine, CA, 92697, USA; Department of Ophthalmology and Center for Translational Vision Research, Gavin Herbert Eye Institute, University of California, Irvine School of Medicine, Irvine, CA, 92697, USA.
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30
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He J, Yamamoto M, Sumiyama K, Konagaya Y, Terai K, Matsuda M, Sato S. Two-photon AMPK and ATP imaging reveals the bias between rods and cones in glycolysis utility. FASEB J 2021; 35:e21880. [PMID: 34449091 DOI: 10.1096/fj.202101121r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/08/2021] [Accepted: 08/11/2021] [Indexed: 12/15/2022]
Abstract
In vertebrates, retinal rod and cone photoreceptor cells rely significantly on glycolysis. Lactate released from photoreceptor cells fuels neighboring retinal pigment epithelium cells and Müller glial cells through oxidative phosphorylation. To understand this highly heterogeneous metabolic environment around photoreceptor cells, single-cell analysis is needed. Here, we visualized cellular AMP-activated protein kinase (AMPK) activity and ATP levels in the retina by two-photon microscopy. Transgenic mice expressing a hyBRET-AMPK biosensor were used for measuring the AMPK activity. GO-ATeam2 transgenic mice were used for measuring the ATP level. Temporal metabolic responses were successfully detected in the live retinal explants upon drug perfusion. A glycolysis inhibitor, 2-deoxy-d-glucose (2-DG), activated AMPK and reduced ATP. These effects were clearly stronger in rods than in cones. Notably, rod AMPK and ATP started to recover at 30 min from the onset of 2-DG perfusion. Consistent with these findings, ex vivo electroretinogram recordings showed a transient slowdown in rod dim flash responses during a 60-min 2-DG perfusion, whereas cone responses were not affected. Based on these results, we propose that cones surrounded by highly glycolytic rods become less dependent on glycolysis, and rods also become less dependent on glycolysis within 60 min upon the glycolysis inhibition.
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Affiliation(s)
- Jiazhou He
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Masamichi Yamamoto
- Department of Research Promotion and Management, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Kenta Sumiyama
- Laboratory for Mouse Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Osaka, Japan
| | - Yumi Konagaya
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Kenta Terai
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Michiyuki Matsuda
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan.,Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, Japan
| | - Shinya Sato
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
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31
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Colozo AT, Vasudevan S, Park PSH. Retinal degeneration in mice expressing the constitutively active G90D rhodopsin mutant. Hum Mol Genet 2021; 29:881-891. [PMID: 31960909 DOI: 10.1093/hmg/ddaa008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/11/2019] [Accepted: 01/15/2020] [Indexed: 11/13/2022] Open
Abstract
Rhodopsin is the G protein-coupled receptor in rod photoreceptor cells that initiates vision upon photon capture. The light receptor is normally locked in an inactive state in the dark by the covalently bound inverse agonist 11-cis retinal. Mutations can render the receptor active even in the absence of light. This constitutive activity can desensitize rod photoreceptor cells and lead to night blindness. A G90D mutation in rhodopsin causes the receptor to be constitutively active and leads to congenital stationary night blindness, which is generally thought to be devoid of retinal degeneration. The constitutively active species responsible for the night blindness phenotype is unclear. Moreover, the classification as a stationary disease devoid of retinal degeneration is also misleading. A transgenic mouse model for congenital stationary night blindness that expresses the G90D rhodopsin mutant was examined to better understand the origin of constitutive activity and the potential for retinal degeneration. Heterozygous mice for the G90D mutation did not exhibit retinal degeneration whereas homozygous mice exhibited progressive retinal degeneration. Only a modest reversal of retinal degeneration was observed when transducin signaling was eliminated genetically, indicating that some of the retinal degeneration occurred in a transducin-independent manner. Biochemical studies on purified rhodopsin from mice indicated that multiple species can potentially contribute to the constitutive activity causing night blindness.
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Affiliation(s)
- Alejandro T Colozo
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sreelakshmi Vasudevan
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
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32
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Abstract
Inherited retinal diseases (IRDs) are an important cause of blindness worldwide. Over 270 genes have been associated with IRD. Genetic testing can determine the cause of the clinical disease in the majority of patients. However, at least 25-50% of patients with clinical diagnosis of IRD remain unsolved even after whole genome sequencing. Animal models of IRD can be useful for expanding the set of established IRD genes, to gain biological understanding of the function of these genes in the retina, and to test advanced therapeutics prior to human clinical trials. In this chapter some small and large animal models of IRD are discussed including some of the advantages and limitations of each for various forms of retinopathy.
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33
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Rhim I, Coello-Reyes G, Nauhaus I. Variations in photoreceptor throughput to mouse visual cortex and the unique effects on tuning. Sci Rep 2021; 11:11937. [PMID: 34099749 PMCID: PMC8184960 DOI: 10.1038/s41598-021-90650-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/12/2021] [Indexed: 11/24/2022] Open
Abstract
Visual input to primary visual cortex (V1) depends on highly adaptive filtering in the retina. In turn, isolation of V1 computations requires experimental control of retinal adaptation to infer its spatio-temporal-chromatic output. Here, we measure the balance of input to mouse V1, in the anesthetized setup, from the three main photoreceptor opsins-M-opsin, S-opsin, and rhodopsin-as a function of two stimulus dimensions. The first dimension is the level of light adaptation within the mesopic range, which governs the balance of rod and cone inputs to cortex. The second stimulus dimension is retinotopic position, which governs the balance of S- and M-cone opsin input due to the opsin expression gradient in the retina. The fitted model predicts opsin input under arbitrary lighting environments, which provides a much-needed handle on in-vivo studies of the mouse visual system. We use it here to reveal that V1 is rod-mediated in common laboratory settings yet cone-mediated in natural daylight. Next, we compare functional properties of V1 under rod and cone-mediated inputs. The results show that cone-mediated V1 responds to 2.5-fold higher temporal frequencies than rod-mediated V1. Furthermore, cone-mediated V1 has smaller receptive fields, yet similar spatial frequency tuning. V1 responses in rod-deficient (Gnat1-/-) mice confirm that the effects are due to differences in photoreceptor opsin contribution.
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Affiliation(s)
- I Rhim
- Department of Psychology, University of Texas At Austin, 108 E. Dean Keeton, Austin, TX, 78712, USA
- Center for Perceptual Systems, University of Texas At Austin, 108 E. Dean Keeton, Austin, TX, 78712, USA
| | - G Coello-Reyes
- Department of Psychology, University of Texas At Austin, 108 E. Dean Keeton, Austin, TX, 78712, USA
- Center for Perceptual Systems, University of Texas At Austin, 108 E. Dean Keeton, Austin, TX, 78712, USA
| | - I Nauhaus
- Department of Psychology, University of Texas At Austin, 108 E. Dean Keeton, Austin, TX, 78712, USA.
- Department of Neuroscience, University of Texas At Austin, 1 University Station, Stop C7000, Austin, TX, 78712, USA.
- Center for Perceptual Systems, University of Texas At Austin, 108 E. Dean Keeton, Austin, TX, 78712, USA.
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Distinct contribution of cone photoreceptor subtypes to the mammalian biological clock. Proc Natl Acad Sci U S A 2021; 118:2024500118. [PMID: 34050024 PMCID: PMC8179201 DOI: 10.1073/pnas.2024500118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Synchronization of our biological clocks to the environmental day–night cycle critically depends on daily exposure to light. Here, we show that cones transmit distinct photic information to the clock by performing recordings of clock neurons in freely moving mice with cones as their only photoreceptors. This is in contrast to the expectation that exclusively melanopsin and rods fulfil this role. Moreover, we show that especially short-wavelength–sensitive cones as compared to mid-wavelength–sensitive cones are important. The evidence for a role for cones implicates that clocks respond to a broad spectrum of colors rather than to blue light, which can be used to strengthen the clock in humans. Ambient light detection is important for the synchronization of the circadian clock to the external solar cycle. Light signals are sent to the suprachiasmatic nuclei (SCN), the site of the major circadian pacemaker. It has been assumed that cone photoreceptors contribute minimally to synchronization. Here, however, we find that cone photoreceptors are sufficient for mediating entrainment and transmitting photic information to the SCN, as evaluated in mice that have only cones as functional photoreceptors. Using in vivo electrophysiological recordings in the SCN of freely moving cone-only mice, we observed light responses in SCN neuronal activity in response to 60-s pulses of both ultraviolet (UV) (λmax 365 nm) and green (λmax 505 nm) light. Higher irradiances of UV light led to irradiance-dependent enhancements in SCN neuronal activity, whereas higher irradiances of green light led to a reduction in the sustained response with only the transient response remaining. Responses in SCN neuronal activity decayed with a half-max time of ∼9 min for UV light and less than a minute for green light, indicating differential input between short-wavelength–sensitive and mid-wavelength–sensitive cones for the SCN responsiveness. Furthermore, we show that UV light is more effective for photoentrainment than green light. Based on the lack of a full sustained response in cone-only mice, we confirmed that rapidly alternating light levels, rather than slowly alternating light, caused substantial phase shifts. Together, our data provide strong evidence that cone types contribute to photoentrainment and differentially affect the electrical activity levels of the SCN.
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Ma G, Son T, Kim TH, Yao X. In vivo optoretinography of phototransduction activation and energy metabolism in retinal photoreceptors. JOURNAL OF BIOPHOTONICS 2021; 14:e202000462. [PMID: 33547871 PMCID: PMC8240094 DOI: 10.1002/jbio.202000462] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 01/09/2021] [Accepted: 02/02/2021] [Indexed: 05/05/2023]
Abstract
The objective of this study is to verify the anatomic correlate of the second (2nd) outer retina band in optical coherence tomography (OCT), and to demonstrate the potential of using intrinsic optical signal (IOS) imaging for concurrent optoretinography (ORG) of phototransduction activation and energy metabolism in stimulus activated retinal photoreceptors. A custom-designed OCT was employed for depth-resolved IOS imaging in mouse retina activated by a visible light flicker stimulation. The spatiotemporal properties of the IOS changes at the photoreceptor outer segment (OS) and inner segment (IS) were quantitatively evaluated. Rapid IOS change was observed at the OS almost right away, and the IOS at the IS was relatively slow. Comparative analysis indicates that the OS-IOS reflects transient OS deformation caused by the phototransduction activation, and IS-IOS might reflect the energy metabolism caused by mitochondria activation in retinal photoreceptors. The consistency of the distribution of the IS-IOS and the 2nd OCT band supports the IS ellipsoid (ISe), which has abundant mitochondria, as the signal source of the 2nd OCT band of the outer retina.
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Affiliation(s)
- Guangying Ma
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
| | - Taeyoon Son
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
| | - Tae-Hoon Kim
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois
- Correspondence: Xincheng Yao, Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
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Ribeiro J, Procyk CA, West EL, O'Hara-Wright M, Martins MF, Khorasani MM, Hare A, Basche M, Fernando M, Goh D, Jumbo N, Rizzi M, Powell K, Tariq M, Michaelides M, Bainbridge JWB, Smith AJ, Pearson RA, Gonzalez-Cordero A, Ali RR. Restoration of visual function in advanced disease after transplantation of purified human pluripotent stem cell-derived cone photoreceptors. Cell Rep 2021; 35:109022. [PMID: 33882303 PMCID: PMC8065177 DOI: 10.1016/j.celrep.2021.109022] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 01/08/2021] [Accepted: 03/31/2021] [Indexed: 12/19/2022] Open
Abstract
Age-related macular degeneration and other macular diseases result in the loss of light-sensing cone photoreceptors, causing irreversible sight impairment. Photoreceptor replacement may restore vision by transplanting healthy cells, which must form new synaptic connections with the recipient retina. Despite recent advances, convincing evidence of functional connectivity arising from transplanted human cone photoreceptors in advanced retinal degeneration is lacking. Here, we show restoration of visual function after transplantation of purified human pluripotent stem cell-derived cones into a mouse model of advanced degeneration. Transplanted human cones elaborate nascent outer segments and make putative synapses with recipient murine bipolar cells (BCs), which themselves undergo significant remodeling. Electrophysiological and behavioral assessments demonstrate restoration of surprisingly complex light-evoked retinal ganglion cell responses and improved light-evoked behaviors in treated animals. Stringent controls exclude alternative explanations, including material transfer and neuroprotection. These data provide crucial validation for photoreceptor replacement therapy and for the potential to rescue cone-mediated vision.
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Affiliation(s)
- Joana Ribeiro
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Emma L West
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Monica F Martins
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Aura Hare
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Mark Basche
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Milan Fernando
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Debbie Goh
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Neeraj Jumbo
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Matteo Rizzi
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Kate Powell
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Menahil Tariq
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | | | - Alexander J Smith
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Rachael A Pearson
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Robin R Ali
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK; Kellogg Eye Centre, University of Michigan, 1000 Wall St., Ann Arbor, MI 48105, USA.
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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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Wong KY, Fernandez FX. Circadian Responses to Light-Flash Exposure: Conceptualization and New Data Guiding Future Directions. Front Neurol 2021; 12:627550. [PMID: 33643205 PMCID: PMC7905211 DOI: 10.3389/fneur.2021.627550] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/21/2021] [Indexed: 01/03/2023] Open
Abstract
A growing number of studies document circadian phase-shifting after exposure to millisecond light flashes. When strung together by intervening periods of darkness, these stimuli evoke pacemaker responses rivaling or outmatching those created by steady luminance, suggesting that the circadian system's relationship to light can be contextualized outside the principle of simple dose-dependence. In the current review, we present a brief chronology of this work. We then develop a conceptual model around it that attempts to relate the circadian effects of flashes to a natural integrative process the pacemaker uses to intermittently sample the photic information available at dawn and dusk. Presumably, these snapshots are employed as building blocks in the construction of a coherent representation of twilight the pacemaker consults to orient the next day's physiology (in that way, flash-resetting of pacemaker rhythms might be less an example of a circadian visual illusion and more an example of the kinds of gestalt inferences that the image-forming system routinely makes when identifying objects within the visual field; i.e., closure). We conclude our review with a discussion on the role of cones in the pacemaker's twilight predictions, providing new electrophysiological data suggesting that classical photoreceptors—but not melanopsin—are necessary for millisecond, intermediate-intensity flash responses in ipRGCs (intrinsically photosensitive retinal ganglion cells). Future investigations are necessary to confirm this “Cone Sentinel Model” of circadian flash-integration and twilight-prediction, and to further define the contribution of cones vs. rods in transducing pacemaker flash signals.
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Affiliation(s)
- Kwoon Y Wong
- Department of Molecular, Cellular, & Developmental Biology, University of Michigan, Ann Arbor, MI, United States.,Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Fabian-Xosé Fernandez
- Department of Psychology, BIO5 Research Institute, University of Arizona, Tucson, AZ, United States.,Department of Neurology, McKnight Brain Research Institute, University of Arizona, Tucson, AZ, United States
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Kolesnikov AV, Kiser PD, Palczewski K, Kefalov VJ. Function of mammalian M-cones depends on the level of CRALBP in Müller cells. J Gen Physiol 2021; 153:211551. [PMID: 33216847 PMCID: PMC7685772 DOI: 10.1085/jgp.202012675] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/16/2020] [Accepted: 10/27/2020] [Indexed: 12/24/2022] Open
Abstract
Cone photoreceptors mediate daytime vision in vertebrates. The rapid and efficient regeneration of their visual pigments following photoactivation is critical for the cones to remain photoresponsive in bright and rapidly changing light conditions. Cone pigment regeneration depends on the recycling of visual chromophore, which takes place via the canonical visual cycle in the retinal pigment epithelium (RPE) and the Müller cell-driven intraretinal visual cycle. The molecular mechanisms that enable the neural retina to regenerate visual chromophore for cones have not been fully elucidated. However, one known component of the two visual cycles is the cellular retinaldehyde-binding protein (CRALBP), which is expressed both in the RPE and in Müller cells. To understand the significance of CRALBP in cone pigment regeneration, we examined the function of cones in mice heterozygous for Rlbp1, the gene encoding CRALBP. We found that CRALBP expression was reduced by ∼50% in both the RPE and retina of Rlbp1+/- mice. Electroretinography (ERG) showed that the dark adaptation of rods and cones is unaltered in Rlbp1+/- mice, indicating a normal RPE visual cycle. However, pharmacologic blockade of the RPE visual cycle revealed suppressed cone dark adaptation in Rlbp1+/- mice in comparison with controls. We conclude that the expression level of CRALPB specifically in the Müller cells modulates the efficiency of the retina visual cycle. Finally, blocking the RPE visual cycle also suppressed further cone dark adaptation in Rlbp1-/- mice, revealing a shunt in the classical RPE visual cycle that bypasses CRALBP and allows partial but unexpectedly rapid cone dark adaptation.
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Affiliation(s)
- Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO
| | - Philip D Kiser
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA.,Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translation Vision Research, School of Medicine, University of California, Irvine, Irvine, CA.,Research Service, VA Long Beach Healthcare System, Long Beach, CA
| | - Krzysztof Palczewski
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA.,Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translation Vision Research, School of Medicine, University of California, Irvine, Irvine, CA.,Department of Chemistry, School of Medicine, University of California, Irvine, Irvine, CA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO
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40
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Chai Z, Silverman D, Li G, Williams D, Raviola E, Yau KW. Light-dependent photoreceptor orientation in mouse retina. SCIENCE ADVANCES 2020; 6:6/51/eabe2782. [PMID: 33328242 PMCID: PMC7744070 DOI: 10.1126/sciadv.abe2782] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/04/2020] [Indexed: 05/25/2023]
Abstract
Almost a century ago, Stiles and Crawford reported that the human eye is more sensitive to light entering through the pupil center than through its periphery (Stiles-Crawford effect). This psychophysical phenomenon, later found to correlate with photoreceptor orientation toward the pupil, was dynamically phototropic, adjustable within days to an eccentrically displaced pupil. For decades, this phototropism has been speculated to involve coordinated movements of the rectilinear photoreceptor outer and inner segments. We report here that, unexpectedly, the murine photoreceptor outer segment has a seemingly light-independent orientation, but the inner segment's orientation undergoes light-dependent movement, giving rise to nonrectilinear outer and inner segments in adult mice born and reared in darkness. Light during an early critical period (~P0 to P8), however, largely sets the correct photoreceptor orientation permanently afterward. Unexpectedly, abolishing rod and cone phototransductions did not mimic darkness in early life, suggesting photosignaling extrinsic to rods and cones is involved.
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Affiliation(s)
- Zuying Chai
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Daniel Silverman
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Guang Li
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - David Williams
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Elio Raviola
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - King-Wai Yau
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Rhodopsin-mediated light-off-induced protein kinase A activation in mouse rod photoreceptor cells. Proc Natl Acad Sci U S A 2020; 117:26996-27003. [PMID: 33046651 DOI: 10.1073/pnas.2009164117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Light-induced extrasynaptic dopamine release in the retina reduces adenosine 3',5'-cyclic monophosphate (cAMP) in rod photoreceptor cells, which is thought to mediate light-dependent desensitization. However, the fine time course of the cAMP dynamics in rods remains elusive due to technical difficulty. Here, we visualized the spatiotemporal regulation of cAMP-dependent protein kinase (PKA) in mouse rods by two-photon live imaging of retinal explants of PKAchu mice, which express a fluorescent biosensor for PKA. Unexpectedly, in addition to the light-on-induced suppression, we observed prominent light-off-induced PKA activation. This activation required photopic light intensity and was confined to the illuminated rods. The estimated maximum spectral sensitivity of 489 nm and loss of the light-off-induced PKA activation in rod-transducin-knockout retinas strongly suggest the involvement of rhodopsin. In support of this notion, rhodopsin-deficient retinal explants showed only the light-on-induced PKA suppression. Taken together, these results suggest that, upon photopic light stimulation, rhodopsin and dopamine signals are integrated to shape the light-off-induced cAMP production and following PKA activation. This may support the dark adaptation of rods.
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Zhang CJ, Ma Y, Jin ZB. The road to restore vision with photoreceptor regeneration. Exp Eye Res 2020; 202:108283. [PMID: 33010290 DOI: 10.1016/j.exer.2020.108283] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 09/13/2020] [Accepted: 09/24/2020] [Indexed: 12/12/2022]
Abstract
Neuroretinal diseases are the predominant cause of irreversible blindness worldwide, mainly due to photoreceptor loss. Currently, there are no radical treatments to fully reverse the degeneration or even stop the disease progression. Thus, it is urgent to develop new biological therapeutics for these diseases on the clinical side. Stem cell-based treatments have become a promising therapeutic for neuroretinal diseases through the replacement of damaged cells with photoreceptors and some allied cells. To date, considerable efforts have been made to regenerate the diseased retina based on stem cell technology. In this review, we overview the current status of stem cell-based treatments for photoreceptor regeneration, including the major cell sources derived from different stem cells in pre-clinical or clinical trial stages. Additionally, we discuss herein the major challenges ahead for and potential new strategy toward photoreceptor regeneration.
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Affiliation(s)
- Chang-Jun Zhang
- Laboratory for Stem Cell & Retinal Regeneration, The Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China
| | - Ya Ma
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Science Key Laboratory, Beijing, 100730, China
| | - Zi-Bing Jin
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Science Key Laboratory, Beijing, 100730, China.
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Abstract
Numerous rhodopsin mutations have been implicated in night blindness and retinal degeneration, often with unclear etiology. D190N-rhodopsin (D190N-Rho) is a well-known inherited human mutation causing retinitis pigmentosa. Both higher-than-normal spontaneous-isomerization activity and misfolding/mistargeting of the mutant protein have been proposed as causes of the disease, but neither explanation has been thoroughly examined. We replaced wild-type rhodopsin (WT-Rho) in RhoD190N/WT mouse rods with a largely "functionally silenced" rhodopsin mutant to isolate electrical responses triggered by D190N-Rho activity, and found that D190N-Rho at the single-molecule level indeed isomerizes more frequently than WT-Rho by over an order of magnitude. Importantly, however, this higher molecular dark activity does not translate into an overall higher cellular dark noise, owing to diminished D190N-Rho content in the rod outer segment. Separately, we found that much of the degeneration and shortened outer-segment length of RhoD190N/WT mouse rods was not averted by ablating rod transducin in phototransduction-also consistent with D190N-Rho's higher isomerization activity not being the primary cause of disease. Instead, the low pigment content, shortened outer-segment length, and a moderate unfolded protein response implicate protein misfolding as the major pathogenic problem. Finally, D190N-Rho also provided some insight into the mechanism of spontaneous pigment excitation.
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Bonezzi PJ, Tarchick MJ, Renna JM. Ex vivo electroretinograms made easy: performing ERGs using 3D printed components. J Physiol 2020; 598:4821-4842. [PMID: 32886799 DOI: 10.1113/jp280014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 09/02/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Rod and cone photoreceptors convert light into electrochemical signals that are transferred to second order cells, initiating image-forming visual processing. Electroretinograms (ERGs) can detect the associated light-induced extracellular transretinal events, allowing for physiological assessment of cellular activity from morphologically intact retinas. We outline a method for economically configuring a traditional patch-clamp rig for performing high signal-to-noise ex vivo ERGs. We accomplish this by incorporating various 3D printed components and by modifying existing light pathways in a typical patch-clamp rig. This methodology provides an additional set of tools to labs interested in studying the physiological function of neuronal populations in isolated retinal tissue. ABSTRACT Rod and cone photoreceptors of the retina are responsible for the initial stages in vision and convey sensory information regarding our visual world across a wide range of lighting conditions. These photoreceptors hyperpolarize in the presence of light and subsequently transmit signals to second-order bipolar and horizontal cells. The electrical components of these events are experimentally detectable, and in conjunction with pharmacological agents, can be further separated into their respective cellular contributions using electroretinograms (ERGs). Extracellular activity from populations of rods and cones generate the negative-going a-wave, while ON-bipolar cells generate positive-going b-waves. ERGs can be performed in vivo or alternatively using an ex vivo configuration, where retinas are isolated and transretinal photovoltages are recorded at high signal-to-noise ratios. However, most ERG set-ups require their own unique set of tools. We demonstrate how, at low cost, to reconfigure a typical patch-clamp rig for ERG recordings. The bulk of these modifications require implementation of various 3D printed components, which can alternatively aid in generating a stand-alone ERG set-up without a patch-rig. Further, we discuss how to configure an ERG system without a patch-clamp rig. Compared to in vivo ERGs, these are superior when measuring small responses, such as those that are cone-evoked or those from immature mouse retinae. This recording configuration provides high signal-to-noise detection of a-waves (300-600 µV) and b-waves (1-3 mV), and is ultimately capable of discerning small (1-2 µV) photovoltages from noise. These quick and economical modifications allow researchers to equip their technical arsenal with an interchangeable patch-clamp/ERG system.
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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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Abstract
The visual phototransduction cascade begins with a cis-trans photoisomerization of a retinylidene chromophore associated with the visual pigments of rod and cone photoreceptors. Visual opsins release their all-trans-retinal chromophore following photoactivation, which necessitates the existence of pathways that produce 11-cis-retinal for continued formation of visual pigments and sustained vision. Proteins in the retinal pigment epithelium (RPE), a cell layer adjacent to the photoreceptor outer segments, form the well-established "dark" regeneration pathway known as the classical visual cycle. This pathway is sufficient to maintain continuous rod function and support cone photoreceptors as well although its throughput has to be augmented by additional mechanism(s) to maintain pigment levels in the face of high rates of photon capture. Recent studies indicate that the classical visual cycle works together with light-dependent processes in both the RPE and neural retina to ensure adequate 11-cis-retinal production under natural illuminances that can span ten orders of magnitude. Further elucidation of the interplay between these complementary systems is fundamental to understanding how cone-mediated vision is sustained in vivo. Here, we describe recent advances in understanding how 11-cis-retinal is synthesized via light-dependent mechanisms.
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Begum M, Joiner DP, Ts'o DY. Stimulus-Driven Retinal Intrinsic Signal Optical Imaging in Mouse Demonstrates a Dominant Rod-Driven Component. Invest Ophthalmol Vis Sci 2020; 61:37. [PMID: 32721018 PMCID: PMC7425724 DOI: 10.1167/iovs.61.8.37] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 06/18/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose The primary hypotheses tested are that (1) there exist stimulus-driven intrinsic optical signals in the mouse retina similar to those previously observed in other species, and (2) these optical signals require an intact rod photoreceptor phototransduction cascade. Methods We used 38 wild-type C57BL6J mice and 18 genetic knockout Gnat1-/- mice to study the light-evoked retinal intrinsic response. A custom mouse fundus camera delivered visual stimuli and collected mouse retinal imaging data of changes in retinal reflectance for further analysis. The retina was stimulated in the high-mesopic range with a 505-nm light-emitting diode while also being illuminated with 780-nm near-infrared light. Results Wild-type C57BL6J mice yielded retinal imaging signals that typically showed a stimulus-driven decrease in retinal reflectance of ∼0.1%, with a time course of several seconds. The signals exhibit spatial specificity in the retina. Overall, the mouse imaging signals are similar in sign and time course to those reported in other mammalian species but are of lower amplitude. In contrast, functional retinal imaging of Gnat1-/- mice that lack a functional rod transducin yielded no such stimulus-driven signals. Conclusions Previous studies have not shown which pathway component is essential for the generation of these imaged signals. The absence of the intrinsic signal responses in Gnat1-/- knockout mice indicates that a functional rod transducin is likely to be necessary for generating the retinal intrinsic signals. These studies, to the best of our knowledge, demonstrate for the first time in vivo mouse retinal functional imaging signals similar to those previously shown in other mammalian species.
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Affiliation(s)
| | | | - Daniel Y. Ts'o
- Department of Neurosurgery, SUNY Upstate Medical University, Syracuse, New York, United States
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Xue Y, Razafsky D, Hodzic D, Kefalov VJ. Mislocalization of cone nuclei impairs cone function in mice. FASEB J 2020; 34:10242-10249. [PMID: 32539195 DOI: 10.1096/fj.202000568r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/16/2020] [Accepted: 05/19/2020] [Indexed: 11/11/2022]
Abstract
The nuclei of cone photoreceptors are located on the apical side of the outer nuclear layer (ONL) in vertebrate retinas. However, the functional role of this evolutionarily conserved localization of cone nuclei is unknown. We previously showed that Linkers of the Nucleoskeleton to the Cytoskeleton (LINC complexes) are essential for the apical migration of cone nuclei during development. Here, we developed an efficient genetic strategy to disrupt cone LINC complexes in mice. Experiments with animals from both sexes revealed that disrupting cone LINC complexes resulted in mislocalization of cone nuclei to the basal side of ONL in mouse retina. This, in turn, disrupted cone pedicle morphology, and appeared to reduce the efficiency of synaptic transmission from cones to bipolar cells. Although we did not observe other developmental or phototransduction defects in cones with mislocalized nuclei, their dark adaptation was impaired, consistent with a deficiency in chromophore recycling. These findings demonstrate that the apical localization of cone nuclei in the ONL is required for the timely dark adaptation and efficient synaptic transmission in cone photoreceptors.
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Affiliation(s)
- Yunlu Xue
- Department of Genetics, Harvard Medical School, Boston, MA, USA.,Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - David Razafsky
- Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Didier Hodzic
- Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
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Senapati S, Park PSH. Differential adaptations in rod outer segment disc membranes in different models of congenital stationary night blindness. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183396. [PMID: 32533975 DOI: 10.1016/j.bbamem.2020.183396] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/01/2020] [Accepted: 06/08/2020] [Indexed: 01/20/2023]
Abstract
Rod photoreceptor cells initiate scotopic vision when the light receptor rhodopsin absorbs a photon of light to initiate phototransduction. These photoreceptor cells are exquisitely sensitive and have adaptive mechanisms in place to maintain optimal function and to overcome dysfunctional states. One adaptation rod photoreceptor cells exhibit is in the packing properties of rhodopsin within the membrane. The mechanism underlying these adaptations is unclear. Mouse models of congenital stationary night blindness with different molecular causes were investigated to determine which signals are important for adaptations in rod photoreceptor cells. Night blindness in these mice is caused by dysfunction in either rod photoreceptor cell signaling or bipolar cell signaling. Changes in the packing of rhodopsin within photoreceptor cell membranes were examined by atomic force microscopy. Mice expressing constitutively active rhodopsin did not exhibit any adaptations, even under constant dark conditions. Mice with disrupted bipolar cell signaling exhibited adaptations, however, they were distinct from those in mice with disrupted phototransduction. These differential adaptations demonstrate that although multiple molecular defects can lead to a similar primary defect causing disease (i.e., night blindness), they can cause different secondary effects (i.e., adaptations). The lighting environment or signaling defects present from birth and during early rearing can condition mice and affect the adaptations occurring in more mature animals. A comparison of effects in wild-type mice, mice with defective phototransduction, and mice with defective bipolar cell signaling, indicated that bipolar cell signaling plays a role in this conditioning but is not required for adaptations in more mature animals.
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Affiliation(s)
- Subhadip Senapati
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA.
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Chen NS, Ingram NT, Frederiksen R, Sampath AP, Chen J, Fain GL. Diminished Cone Sensitivity in cpfl3 Mice Is Caused by Defective Transducin Signaling. Invest Ophthalmol Vis Sci 2020; 61:26. [PMID: 32315379 PMCID: PMC7401474 DOI: 10.1167/iovs.61.4.26] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Purpose Cone photoreceptor function loss 3 (Gnat2cpfl3/cpfl3 or cpfl3) is a mouse model commonly used as a functional cones null from a naturally occurring mutation in the α-subunit of cone transducin (Gnat2). We nevertheless detected robust cone-mediated light responses from cpfl3 animals, which we now explore. Methods Recordings were made from whole retina and from identified cones with whole-cell patch clamp in retinal slices. Relative levels of GNAT2 protein and numbers of cones in isolated retinas were compared between cpfl3, rod transducin knockout (Gnat1-/-), cpfl3/Gnat1-/- double mutants, and control C57Bl/6J age-matched mice at 4, 9, and 14 weeks of age. Results Cones from cpfl3 and cpfl3/Gnat1-/- mice 2 to 3 months of age displayed normal dark currents but greatly reduced sensitivity and amplification constants. Responses decayed more slowly than in control (C57Bl/6J) mice, indicating an altered mechanism of inactivation. At dim light intensities rod responses could be recorded from cpfl3 cones, indicating intact rod/cone gap junctions. The cpfl3 and cpfl3/Gnat1-/- mice express two-fold less GNAT2 protein compared with C57 at 4 weeks, and a four-fold decrease by 14 weeks. This is accompanied by a small decrease in the number of cones. Conclusions Cplf3 cones can respond to light with currents of normal amplitude and cannot be assumed to be a Gnat2 null. The decreased sensitivity and amplification rate of cones is not explained by a reduction in GNAT2 protein level, but instead by abnormal interactions of the mutant transducin with rhodopsin and the effector molecule, cGMP phosphodiesterase.
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Affiliation(s)
- Natalie S. Chen
- Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, California, United States
| | - Norianne T. Ingram
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine, Los Angeles, California, United States,Department of Integrative Biology and Physiology, University of California, Los Angeles, California,United States
| | - Rikard Frederiksen
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine, Los Angeles, California, United States
| | - Alapakkam P. Sampath
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine, Los Angeles, California, United States
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, California, United States
| | - Gordon L. Fain
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine, Los Angeles, California, United States,Department of Integrative Biology and Physiology, University of California, Los Angeles, California,United States
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