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Kerschensteiner D. Losing, preserving, and restoring vision from neurodegeneration in the eye. Curr Biol 2023; 33:R1019-R1036. [PMID: 37816323 PMCID: PMC10575673 DOI: 10.1016/j.cub.2023.08.044] [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] [Indexed: 10/12/2023]
Abstract
The retina is a part of the brain that sits at the back of the eye, looking out onto the world. The first neurons of the retina are the rod and cone photoreceptors, which convert changes in photon flux into electrical signals that are the basis of vision. Rods and cones are frequent targets of heritable neurodegenerative diseases that cause visual impairment, including blindness, in millions of people worldwide. This review summarizes the diverse genetic causes of inherited retinal degenerations (IRDs) and their convergence onto common pathogenic mechanisms of vision loss. Currently, there are few effective treatments for IRDs, but recent advances in disparate areas of biology and technology (e.g., genome editing, viral engineering, 3D organoids, optogenetics, semiconductor arrays) discussed here enable promising efforts to preserve and restore vision in IRD patients with implications for neurodegeneration in less approachable brain areas.
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Affiliation(s)
- Daniel Kerschensteiner
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Li S, Ma H, Yang F, Ding X. cGMP Signaling in Photoreceptor Degeneration. Int J Mol Sci 2023; 24:11200. [PMID: 37446378 PMCID: PMC10342299 DOI: 10.3390/ijms241311200] [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: 05/23/2023] [Revised: 07/04/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023] Open
Abstract
Photoreceptors in the retina are highly specialized neurons with photosensitive molecules in the outer segment that transform light into chemical and electrical signals, and these signals are ultimately relayed to the visual cortex in the brain to form vision. Photoreceptors are composed of rods and cones. Rods are responsible for dim light vision, whereas cones are responsible for bright light, color vision, and visual acuity. Photoreceptors undergo progressive degeneration over time in many hereditary and age-related retinal diseases. Despite the remarkable heterogeneity of disease-causing genes, environmental factors, and pathogenesis, the progressive death of rod and cone photoreceptors ultimately leads to loss of vision/blindness. There are currently no treatments available for retinal degeneration. Cyclic guanosine 3', 5'-monophosphate (cGMP) plays a pivotal role in phototransduction. cGMP governs the cyclic nucleotide-gated (CNG) channels on the plasma membrane of the photoreceptor outer segments, thereby regulating membrane potential and signal transmission. By gating the CNG channels, cGMP regulates cellular Ca2+ homeostasis and signal transduction. As a second messenger, cGMP activates the cGMP-dependent protein kinase G (PKG), which regulates numerous targets/cellular events. The dysregulation of cGMP signaling is observed in varieties of photoreceptor/retinal degenerative diseases. Abnormally elevated cGMP signaling interferes with various cellular events, which ultimately leads to photoreceptor degeneration. In line with this, strategies to reduce cellular cGMP signaling result in photoreceptor protection in mouse models of retinal degeneration. The potential mechanisms underlying cGMP signaling-induced photoreceptor degeneration involve the activation of PKG and impaired Ca2+ homeostasis/Ca2+ overload, resulting from overactivation of the CNG channels, as well as the subsequent activation of the downstream cellular stress/death pathways. Thus, targeting the cellular cGMP/PKG signaling and the Ca2+-regulating pathways represents a significant strategy for photoreceptor protection in retinal degenerative diseases.
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Affiliation(s)
| | | | | | - Xiqin Ding
- Department of Cell Biology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (S.L.); (H.M.); (F.Y.)
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Geada S, Teixeira-Marques F, Teixeira B, Carvalho AL, Lousan N, Saraiva J, Murta J, Silva R, Zanlonghi X, Defoort-Dhellemmes S, Smirnov V, Dhaenens CM, Blanchet C, Meunier I, Marques JP. Mutational Spectrum, Ocular and Olfactory Phenotypes of CNGB1-Related RP-Olfactory Dysfunction Syndrome in a Multiethnic Cohort. Genes (Basel) 2023; 14:genes14040830. [PMID: 37107588 PMCID: PMC10137467 DOI: 10.3390/genes14040830] [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: 01/29/2023] [Revised: 03/17/2023] [Accepted: 03/26/2023] [Indexed: 04/29/2023] Open
Abstract
CNGB1 gene mutations are a well-known cause of autosomal recessive retinitis pigmentosa (RP), which was recently associated with olfactory dysfunction. The purpose of this study was to report the molecular spectrum and the ocular and olfactory phenotypes of a multiethnic cohort with CNGB1-associated RP. A cross-sectional case series was conducted at two ophthalmic genetics referral centers. Consecutive patients with molecularly confirmed CNGB1-related RP were included. All patients underwent a complete ophthalmological examination complemented by psychophysical olfactory evaluation. Fifteen patients (10 families: 8 Portuguese, 1 French, and 1 Turkish), mean aged 57.13 ± 15.37 years old (yo), were enrolled. Seven disease-causing variants were identified, two of which are reported for the first time: c.2565_2566del and c.2285G > T. Although 11/15 patients reported onset of nyctalopia before age 10, diagnosis was only established after 30 yo in 9/15. Despite widespread retinal degeneration being present in 14/15 probands, a relatively preserved visual acuity was observed throughout follow-up. Olfactory function was preserved in only 4/15 patients, all of whom carried at least one missense variant. Our study supports previous reports of an autosomal recessive RP-olfactory dysfunction syndrome in association with certain disease-causing variants in the CNGB1 gene and expands the mutational spectrum of CNGB1-related disease by reporting two novel variants.
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Affiliation(s)
- Sara Geada
- Ophthalmology Unit, Centro Hospitalar e Universitário de Coimbra (CHUC), 3000-075 Coimbra, Portugal
| | - Francisco Teixeira-Marques
- Department of Otorhinolaryngology, Centro Hospitalar do Tâmega e Sousa (CHTS), 4560-162 Penafiel, Portugal
| | - Bruno Teixeira
- Ophthalmology Unit, Centro Hospitalar e Universitário de Coimbra (CHUC), 3000-075 Coimbra, Portugal
| | - Ana Luísa Carvalho
- Medical Genetics Unit, Centro Hospitalar e Universitário de Coimbra, 3000-602 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-354 Coimbra, Portugal
- University Clinic of Medical Genetics, Faculty of Medicine, University of Coimbra (FMUC), 3000-354 Coimbra, Portugal
- University Clinic of Pediatrics, Faculty of Medicine, University of Coimbra (FMUC), 3000-354 Coimbra, Portugal
| | - Nuno Lousan
- Department of Otorhinolaryngology, Centro Hospitalar do Tâmega e Sousa (CHTS), 4560-162 Penafiel, Portugal
| | - Jorge Saraiva
- Medical Genetics Unit, Centro Hospitalar e Universitário de Coimbra, 3000-602 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-354 Coimbra, Portugal
- University Clinic of Medical Genetics, Faculty of Medicine, University of Coimbra (FMUC), 3000-354 Coimbra, Portugal
- University Clinic of Pediatrics, Faculty of Medicine, University of Coimbra (FMUC), 3000-354 Coimbra, Portugal
| | - Joaquim Murta
- Ophthalmology Unit, Centro Hospitalar e Universitário de Coimbra (CHUC), 3000-075 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-354 Coimbra, Portugal
- University Clinic of Ophthalmology, Faculty of Medicine, University of Coimbra (FMUC), 3000-354 Coimbra, Portugal
| | - Rufino Silva
- Ophthalmology Unit, Centro Hospitalar e Universitário de Coimbra (CHUC), 3000-075 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-354 Coimbra, Portugal
- University Clinic of Ophthalmology, Faculty of Medicine, University of Coimbra (FMUC), 3000-354 Coimbra, Portugal
| | - Xavier Zanlonghi
- Eye Department, Rennes University Hospital, 35 033 Rennes, France
| | - Sabine Defoort-Dhellemmes
- Department of Visual Exploration and Neuro-Ophthalmology, Robert Salengro Hospital, 59 037 Lille, France
- Sensgene Care Network, 67 091 Strasbourg, France
| | - Vasily Smirnov
- Department of Visual Exploration and Neuro-Ophthalmology, Robert Salengro Hospital, 59 037 Lille, France
- Sensgene Care Network, 67 091 Strasbourg, France
| | - Claire-Marie Dhaenens
- University of Lille, INSERM, CHU Lille, U1172-LilNCog-Lille Neuroscience & Cognition, 59 000 Lille, France
| | - Catherine Blanchet
- Reference Centre for Inherited Sensory Diseases, Montpellier University Hospital, 34 295 Montpellier, France
| | - Isabelle Meunier
- Sensgene Care Network, 67 091 Strasbourg, France
- Reference Centre for Inherited Sensory Diseases, Montpellier University Hospital, 34 295 Montpellier, France
- Institute for Neurosciences of Montpellier (INM), University of Montpellier, INSERM, 34 091 Montpellier, France
| | - João Pedro Marques
- Ophthalmology Unit, Centro Hospitalar e Universitário de Coimbra (CHUC), 3000-075 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-354 Coimbra, Portugal
- University Clinic of Ophthalmology, Faculty of Medicine, University of Coimbra (FMUC), 3000-354 Coimbra, Portugal
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Lynn J, Raney A, Britton N, Ramoin J, Yang RW, Radojevic B, McClard CK, Kingsley R, Coussa RG, Bennett LD. Genetic Diagnosis for 64 Patients with Inherited Retinal Disease. Genes (Basel) 2022; 14:74. [PMID: 36672815 PMCID: PMC9859429 DOI: 10.3390/genes14010074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/07/2022] [Accepted: 12/23/2022] [Indexed: 12/28/2022] Open
Abstract
The overlapping genetic and clinical spectrum in inherited retinal degeneration (IRD) creates challenges for accurate diagnoses. The goal of this work was to determine the genetic diagnosis and clinical features for patients diagnosed with an IRD. After signing informed consent, peripheral blood or saliva was collected from 64 patients diagnosed with an IRD. Genetic testing was performed on each patient in a Clinical Laboratory Improvement Amendments of 1988 (CLIA) certified laboratory. Mutations were verified with Sanger sequencing and segregation analysis when possible. Visual acuity was measured with a traditional Snellen chart and converted to a logarithm of minimal angle of resolution (logMAR). Fundus images of dilated eyes were acquired with the Optos® camera (Dunfermline, UK). Horizontal line scans were obtained with spectral-domain optical coherence tomography (SDOCT; Spectralis, Heidelberg, Germany). Genetic testing combined with segregation analysis resolved molecular and clinical diagnoses for 75% of patients. Ten novel mutations were found and unique genotype phenotype associations were made for the genes RP2 and CEP83. Collective knowledge is thereby expanded of the genetic basis and phenotypic correlation in IRD.
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Affiliation(s)
- Jacob Lynn
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Austin Raney
- College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Nathaniel Britton
- College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Josh Ramoin
- College of Osteopathic Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Ryan W. Yang
- College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Bojana Radojevic
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Dean McGee Eye Institute, Oklahoma City, OK 73104, USA
| | - Cynthia K. McClard
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Dean McGee Eye Institute, Oklahoma City, OK 73104, USA
| | - Ronald Kingsley
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Dean McGee Eye Institute, Oklahoma City, OK 73104, USA
| | - Razek Georges Coussa
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Dean McGee Eye Institute, Oklahoma City, OK 73104, USA
| | - Lea D. Bennett
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Dean McGee Eye Institute, Oklahoma City, OK 73104, USA
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Deller M, Gellrich J, Lohrer EC, Schriever VA. Genetics of congenital olfactory dysfunction: a systematic review of the literature. Chem Senses 2022; 47:6847567. [PMID: 36433800 DOI: 10.1093/chemse/bjac028] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Olfaction, as one of our 5 senses, plays an important role in our daily lives. It is connected to proper nutrition, social interaction, and protection mechanisms. Disorders affecting this sense consequently also affect the patients' general quality of life. Because the underlying genetics of congenital olfactory disorders (COD) have not been thoroughly investigated yet, this systematic review aimed at providing information on genes that have previously been reported to be mutated in patients suffering from COD. This was achieved by systematically reviewing existing literature on 3 databases, namely PubMed, Ovid Medline, and ISI Web of Science. Genes and the type of disorder, that is, isolated and/or syndromic COD were included in this study, as were the patients' associated abnormal features, which were categorized according to the affected organ(-system). Our research yielded 82 candidate genes/chromosome loci for isolated and/or syndromic COD. Our results revealed that the majority of these are implicated in syndromic COD, a few accounted for syndromic and isolated COD, and the least underly isolated COD. Most commonly, structures of the central nervous system displayed abnormalities. This study is meant to assist clinicians in determining the type of COD and detecting potentially abnormal features in patients with confirmed genetic variations. Future research will hopefully expand this list and thereby further improve our understanding of COD.
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Affiliation(s)
- Matthias Deller
- Charité-Universitätsmedizin Berlin, Department of Pediatric Neurology, Berlin, Germany
| | - Janine Gellrich
- Abteilung Neuropädiatrie Medizinische Fakultät Carl Gustav Carus, Technische Universität, Dresden, Germany
| | - Elisabeth C Lohrer
- Abteilung Neuropädiatrie Medizinische Fakultät Carl Gustav Carus, Technische Universität, Dresden, Germany
| | - Valentin A Schriever
- Charité-Universitätsmedizin Berlin, Department of Pediatric Neurology, Berlin, Germany.,Abteilung Neuropädiatrie Medizinische Fakultät Carl Gustav Carus, Technische Universität, Dresden, Germany.,Charité-Universitätsmedizin Berlin, Center for Chronically Sick Children (Sozialpädiatrisches Zentrum, SPZ), Berlin, Germany
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Adherent but Not Suspension-Cultured Embryoid Bodies Develop into Laminated Retinal Organoids. J Dev Biol 2021; 9:jdb9030038. [PMID: 34564087 PMCID: PMC8482155 DOI: 10.3390/jdb9030038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/31/2021] [Accepted: 09/08/2021] [Indexed: 11/23/2022] Open
Abstract
Human induced pluripotent stem cells (iPSCs) are differentiated into three-dimensional (3D) retinal organoids to study retinogenesis and diseases that would otherwise be impossible. The complexity and low yield in current protocols remain a technical challenge, particularly for inexperienced personnel. Differentiation protocols require labor-intensive and time-consuming dissection of optic vesicles (OVs). Here we compare this method with a suspension method of developing retinal organoids. iPSCs were differentiated with standard protocols but the suspension-grown method omitted the re-plating of embryoid bodies and dissection of OVs. All other media and treatments were identical between developmental methods. Developmental maturation was evaluated with RT-qPCR and immunocytochemistry. Dissection- and suspension-derived retinal organoids displayed temporal biogenesis of retinal cell types. Differences in retinal organoids generated by the two methods of differentiation included temporal developmental and the organization of neural retina layers. Retinal organoids grown in suspension showed delayed development and disorganized retinal layers compared to the dissected retinal organoids. We found that omitting the re-plating of EBs to form OVs resulted in numerous OVs that were easy to identify and matured along a retinal lineage. While more efficient, the suspension method led to retinal organoids with disorganized retinal layers compared to those obtained using conventional dissection protocols.
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Functional Evaluation of Splicing for Variants of Uncertain Significance in Patients with Inherited Retinal Diseases. Genes (Basel) 2021; 12:genes12070993. [PMID: 34209753 PMCID: PMC8303747 DOI: 10.3390/genes12070993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 01/13/2023] Open
Abstract
Inherited retinal diseases (IRD) comprise a heterogeneous set of clinical and genetic disorders that lead to blindness. Given the emerging opportunities in precision medicine and gene therapy, it has become increasingly important to determine whether DNA variants with uncertain significance (VUS) are responsible for patients’ IRD. This research was performed to assess the functional consequence of six VUS identified in patients with IRD. Clinical assessments included an ophthalmic examination, best-corrected visual acuity, and kinetic perimetry. Imaging was acquired with the Optos ultra-widefield camera and spectral domain optical coherence tomography (SD-OCT). Genetic testing was performed by Molecular Vision Laboratories. VUS that were predicted to alter splicing were analyzed with a minigene assay, which revealed that VUS in the genes OPA1, CNGB1, and CLUAP1 altered spicing mechanisms. Due to emerging gene and cell therapies, these results expand the genotype-phenotype correlations for patients diagnosed with an IRD.
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