1
|
Nouri Z, Sarmadi A, Narrei S, Kianersi H, Kianersi F, Tabatabaiefar MA. Clinical characterizations and molecular genetic study of two co-segregating variants in PDZD7 and PDE6C genes leading simultaneously to non-syndromic hearing loss and achromatopsia. BMC Med Genomics 2024; 17:173. [PMID: 38956522 PMCID: PMC11218353 DOI: 10.1186/s12920-024-01942-3] [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: 10/08/2023] [Accepted: 06/19/2024] [Indexed: 07/04/2024] Open
Abstract
BACKGROUND Autosomal recessive non-syndromic hearing loss (NSHL) and cone dystrophies (CODs) are highly genetically and phenotypically heterogeneous disorders. In this study, we applied the whole exome sequencing (WES) to find the cause of HL and COD in an Iranian consanguineous family with three affected individuals. METHODS Three members from an Iranian consanguineous family who were suffering from NSHL and visual impairment were ascertained in this study. Comprehensive clinical evaluations and genetic analysis followed by bioinformatic and co-segregation studies were performed to diagnose the cause of these phenotypes. Data were collected from 2020 to 2022. RESULTS All cases showed congenital bilateral NSHL, decreased visual acuity, poor color discrimination, photophobia and macular atrophy. Moreover, cornea, iris and anterior vitreous were within normal limit in both eyes, decreased foveal sensitivity, central scotoma and generalized depression of visual field were seen in three cases. WES results showed two variants, a novel null variant (p.Trp548Ter) in the PDE6C gene causing COD type 4 (Achromatopsia) and a previously reported variant (p.Ile84Thr) in the PDZD7 gene causing NSHL. Both variants were found in the cis configuration on chromosome 10 with a genetic distance of about 8.3 cM, leading to their co-inheritance. However, two diseases could appear independently in subsequent generations due to crossover during meiosis. CONCLUSIONS Here, we could successfully determine the etiology of a seemingly complex phenotype in two adjacent genes. We identified a novel variant in the PDE6C gene, related to achromatopsia. Interestingly, this variant could cooperatively cause visual disorders: cone dystrophy and cone-rod dystrophy.
Collapse
Affiliation(s)
- Zahra Nouri
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Pediatric Inherited Diseases Research Center, Research Institute for Primordial Prevention of Non-Communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Akram Sarmadi
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Pediatric Inherited Diseases Research Center, Research Institute for Primordial Prevention of Non-Communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Sina Narrei
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Department of Research and Development, Harmonic Medical Genetics Lab, Isfahan, Iran
| | - Hamidreza Kianersi
- Isfahan Eye Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Farzan Kianersi
- Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohammad Amin Tabatabaiefar
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
- Pediatric Inherited Diseases Research Center, Research Institute for Primordial Prevention of Non-Communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran.
- University of Medical Sciences, Isfahan, 81746-73461, Iran.
| |
Collapse
|
2
|
Georgiou M, Robson AG, Fujinami K, de Guimarães TAC, Fujinami-Yokokawa Y, Daich Varela M, Pontikos N, Kalitzeos A, Mahroo OA, Webster AR, Michaelides M. Phenotyping and genotyping inherited retinal diseases: Molecular genetics, clinical and imaging features, and therapeutics of macular dystrophies, cone and cone-rod dystrophies, rod-cone dystrophies, Leber congenital amaurosis, and cone dysfunction syndromes. Prog Retin Eye Res 2024; 100:101244. [PMID: 38278208 DOI: 10.1016/j.preteyeres.2024.101244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/12/2024] [Accepted: 01/15/2024] [Indexed: 01/28/2024]
Abstract
Inherited retinal diseases (IRD) are a leading cause of blindness in the working age population and in children. The scope of this review is to familiarise clinicians and scientists with the current landscape of molecular genetics, clinical phenotype, retinal imaging and therapeutic prospects/completed trials in IRD. Herein we present in a comprehensive and concise manner: (i) macular dystrophies (Stargardt disease (ABCA4), X-linked retinoschisis (RS1), Best disease (BEST1), PRPH2-associated pattern dystrophy, Sorsby fundus dystrophy (TIMP3), and autosomal dominant drusen (EFEMP1)), (ii) cone and cone-rod dystrophies (GUCA1A, PRPH2, ABCA4, KCNV2 and RPGR), (iii) predominant rod or rod-cone dystrophies (retinitis pigmentosa, enhanced S-Cone syndrome (NR2E3), Bietti crystalline corneoretinal dystrophy (CYP4V2)), (iv) Leber congenital amaurosis/early-onset severe retinal dystrophy (GUCY2D, CEP290, CRB1, RDH12, RPE65, TULP1, AIPL1 and NMNAT1), (v) cone dysfunction syndromes (achromatopsia (CNGA3, CNGB3, PDE6C, PDE6H, GNAT2, ATF6), X-linked cone dysfunction with myopia and dichromacy (Bornholm Eye disease; OPN1LW/OPN1MW array), oligocone trichromacy, and blue-cone monochromatism (OPN1LW/OPN1MW array)). Whilst we use the aforementioned classical phenotypic groupings, a key feature of IRD is that it is characterised by tremendous heterogeneity and variable expressivity, with several of the above genes associated with a range of phenotypes.
Collapse
Affiliation(s)
- Michalis Georgiou
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom; Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - Anthony G Robson
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Kaoru Fujinami
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom; Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.
| | - Thales A C de Guimarães
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Yu Fujinami-Yokokawa
- UCL Institute of Ophthalmology, University College London, London, United Kingdom; Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan; Department of Health Policy and Management, Keio University School of Medicine, Tokyo, Japan.
| | - Malena Daich Varela
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Nikolas Pontikos
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Angelos Kalitzeos
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Omar A Mahroo
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom; Section of Ophthalmology, King s College London, St Thomas Hospital Campus, London, United Kingdom; Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, United Kingdom; Department of Translational Ophthalmology, Wills Eye Hospital, Philadelphia, PA, USA.
| | - Andrew R Webster
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Michel Michaelides
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| |
Collapse
|
3
|
Yang Z, Yan L, Zhang W, Qi J, An W, Yao K. Dyschromatopsia: a comprehensive analysis of mechanisms and cutting-edge treatments for color vision deficiency. Front Neurosci 2024; 18:1265630. [PMID: 38298913 PMCID: PMC10828017 DOI: 10.3389/fnins.2024.1265630] [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: 07/23/2023] [Accepted: 01/02/2024] [Indexed: 02/02/2024] Open
Abstract
Color blindness is a retinal disease that mainly manifests as a color vision disorder, characterized by achromatopsia, red-green color blindness, and blue-yellow color blindness. With the development of technology and progress in theory, extensive research has been conducted on the genetic basis of color blindness, and various approaches have been explored for its treatment. This article aims to provide a comprehensive review of recent advances in understanding the pathological mechanism, clinical symptoms, and treatment options for color blindness. Additionally, we discuss the various treatment approaches that have been developed to address color blindness, including gene therapy, pharmacological interventions, and visual aids. Furthermore, we highlight the promising results from clinical trials of these treatments, as well as the ongoing challenges that must be addressed to achieve effective and long-lasting therapeutic outcomes. Overall, this review provides valuable insights into the current state of research on color blindness, with the intention of informing further investigation and development of effective treatments for this disease.
Collapse
Affiliation(s)
- Zihao Yang
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Lin Yan
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Wenliang Zhang
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Jia Qi
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Wenjing An
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Kai Yao
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| |
Collapse
|
4
|
Zhang SX, Wang JJ, Starr CR, Lee EJ, Park KS, Zhylkibayev A, Medina A, Lin JH, Gorbatyuk M. The endoplasmic reticulum: Homeostasis and crosstalk in retinal health and disease. Prog Retin Eye Res 2024; 98:101231. [PMID: 38092262 PMCID: PMC11056313 DOI: 10.1016/j.preteyeres.2023.101231] [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: 08/21/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023]
Abstract
The endoplasmic reticulum (ER) is the largest intracellular organelle carrying out a broad range of important cellular functions including protein biosynthesis, folding, and trafficking, lipid and sterol biosynthesis, carbohydrate metabolism, and calcium storage and gated release. In addition, the ER makes close contact with multiple intracellular organelles such as mitochondria and the plasma membrane to actively regulate the biogenesis, remodeling, and function of these organelles. Therefore, maintaining a homeostatic and functional ER is critical for the survival and function of cells. This vital process is implemented through well-orchestrated signaling pathways of the unfolded protein response (UPR). The UPR is activated when misfolded or unfolded proteins accumulate in the ER, a condition known as ER stress, and functions to restore ER homeostasis thus promoting cell survival. However, prolonged activation or dysregulation of the UPR can lead to cell death and other detrimental events such as inflammation and oxidative stress; these processes are implicated in the pathogenesis of many human diseases including retinal disorders. In this review manuscript, we discuss the unique features of the ER and ER stress signaling in the retina and retinal neurons and describe recent advances in the research to uncover the role of ER stress signaling in neurodegenerative retinal diseases including age-related macular degeneration, inherited retinal degeneration, achromatopsia and cone diseases, and diabetic retinopathy. In some chapters, we highlight the complex interactions between the ER and other intracellular organelles focusing on mitochondria and illustrate how ER stress signaling regulates common cellular stress pathways such as autophagy. We also touch upon the integrated stress response in retinal degeneration and diabetic retinopathy. Finally, we provide an update on the current development of pharmacological agents targeting the UPR response and discuss some unresolved questions and knowledge gaps to be addressed by future research.
Collapse
Affiliation(s)
- Sarah X Zhang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States.
| | - Josh J Wang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Christopher R Starr
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Eun-Jin Lee
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Karen Sophia Park
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Assylbek Zhylkibayev
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andy Medina
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Jonathan H Lin
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Marina Gorbatyuk
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
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.
Collapse
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.)
| |
Collapse
|
7
|
Genetic and Clinical Characterization of Danish Achromatopsia Patients. Genes (Basel) 2023; 14:genes14030690. [PMID: 36980963 PMCID: PMC10048638 DOI: 10.3390/genes14030690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 03/16/2023] Open
Abstract
Achromatopsia is a rare congenital condition with cone photoreceptor dysfunction causing color blindness, reduced vision, nystagmus and photophobia. New treatments are being developed, but the current evidence is still conflicting regarding possible progression over time, and there is no clear genotype-phenotype correlation. This natural history study aimed to further explore the course of disease and potential clinical differences between various genotypes. The retrospective design allowed for the study of a large cohort with a long follow-up. Patients were identified from the Danish national registries. If not already available, genetic analysis was offered to the patient. Clinical data from 1945–2022 were retrieved from medical records and included best-corrected visual acuity (BCVA), color vision, refractive error, nystagmus, visual fields and fundoscopic findings. We identified variants believed to be disease causing in five of the known achromatopsia genes: CNGA3; CNGB3; GNAT2; PDE6C and PDE6H; and novel variants were identified in CNGB3 and PDE6C. Progressive deterioration of BCVA only attributable to achromatopsia was found in three of 58 patients. Progressive phenotype was seen with variants in CNGB3 and PDE6C. The results indicate that myopia could be more frequently occurring with variants in GNAT2, PDE6C and PDE6H and support the evidence that achromatopsia is a predominantly stationary condition with respect to BCVA. Although a clear genotype-phenotype correlation can still not be concluded, there may be differences in phenotypical characteristics with variants in different genes.
Collapse
|
8
|
Siles L, Gaudó P, Pomares E. High-Efficiency CRISPR/Cas9-Mediated Correction of a Homozygous Mutation in Achromatopsia-Patient-Derived iPSCs. Int J Mol Sci 2023; 24:ijms24043655. [PMID: 36835061 PMCID: PMC9964936 DOI: 10.3390/ijms24043655] [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: 12/27/2022] [Revised: 02/03/2023] [Accepted: 02/09/2023] [Indexed: 02/15/2023] Open
Abstract
Achromatopsia is an autosomal recessive disorder, in which cone photoreceptors undergo progressive degeneration, causing color blindness and poor visual acuity, among other significant eye affectations. It belongs to a group of inherited retinal dystrophies that currently have no treatment. Although functional improvements have been reported in several ongoing gene therapy studies, more efforts and research should be carried out to enhance their clinical application. In recent years, genome editing has arisen as one of the most promising tools for personalized medicine. In this study, we aimed to correct a homozygous PDE6C pathogenic variant in hiPSCs derived from a patient affected by achromatopsia through CRISPR/Cas9 and TALENs technologies. Here, we demonstrate high efficiency in gene editing by CRISPR/Cas9 but not with TALENs approximation. Despite a few of the edited clones displaying heterozygous on-target defects, the proportion of corrected clones with a potentially restored wild-type PDE6C protein was more than half of the total clones analyzed. In addition, none of them presented off-target aberrations. These results significantly contribute to advances in single-nucleotide gene editing and the development of future strategies for the treatment of achromatopsia.
Collapse
Affiliation(s)
- Laura Siles
- Fundació de Recerca de l’Institut de Microcirurgia Ocular, 08035 Barcelona, Spain
- Departament de Genètica, IMO Grupo Miranza, 08035 Barcelona, Spain
| | - Paula Gaudó
- Fundació de Recerca de l’Institut de Microcirurgia Ocular, 08035 Barcelona, Spain
- Departament de Genètica, IMO Grupo Miranza, 08035 Barcelona, Spain
| | - Esther Pomares
- Fundació de Recerca de l’Institut de Microcirurgia Ocular, 08035 Barcelona, Spain
- Departament de Genètica, IMO Grupo Miranza, 08035 Barcelona, Spain
- Correspondence:
| |
Collapse
|
9
|
Blumer M, Brown T, Freitas MB, Destro AL, Oliveira JA, Morales AE, Schell T, Greve C, Pippel M, Jebb D, Hecker N, Ahmed AW, Kirilenko BM, Foote M, Janke A, Lim BK, Hiller M. Gene losses in the common vampire bat illuminate molecular adaptations to blood feeding. SCIENCE ADVANCES 2022; 8:eabm6494. [PMID: 35333583 PMCID: PMC8956264 DOI: 10.1126/sciadv.abm6494] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/03/2022] [Indexed: 05/06/2023]
Abstract
Vampire bats are the only mammals that feed exclusively on blood. To uncover genomic changes associated with this dietary adaptation, we generated a haplotype-resolved genome of the common vampire bat and screened 27 bat species for genes that were specifically lost in the vampire bat lineage. We found previously unknown gene losses that relate to reduced insulin secretion (FFAR1 and SLC30A8), limited glycogen stores (PPP1R3E), and a unique gastric physiology (CTSE). Other gene losses likely reflect the biased nutrient composition (ERN2 and CTRL) and distinct pathogen diversity of blood (RNASE7) and predict the complete lack of cone-based vision in these strictly nocturnal bats (PDE6H and PDE6C). Notably, REP15 loss likely helped vampire bats adapt to high dietary iron levels by enhancing iron excretion, and the loss of CYP39A1 could have contributed to their exceptional cognitive abilities. These findings enhance our understanding of vampire bat biology and the genomic underpinnings of adaptations to blood feeding.
Collapse
Affiliation(s)
- Moritz Blumer
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
- Goethe University, Faculty of Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Tom Brown
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | | | - Ana Luiza Destro
- Department of Animal Biology, Federal University of Viçosa, Viçosa, Brazil
| | - Juraci A. Oliveira
- Department of General Biology, Federal University of Viçosa, Viçosa, Brazil
| | - Ariadna E. Morales
- Goethe University, Faculty of Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberganlage 25, 60325 Frankfurt, Germany
- Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt, Germany
| | - Tilman Schell
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberganlage 25, 60325 Frankfurt, Germany
- Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt, Germany
| | - Carola Greve
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberganlage 25, 60325 Frankfurt, Germany
- Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt, Germany
| | - Martin Pippel
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - David Jebb
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
| | - Nikolai Hecker
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
| | - Alexis-Walid Ahmed
- Goethe University, Faculty of Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberganlage 25, 60325 Frankfurt, Germany
- Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt, Germany
| | - Bogdan M. Kirilenko
- Goethe University, Faculty of Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberganlage 25, 60325 Frankfurt, Germany
- Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt, Germany
| | - Maddy Foote
- Native Bat Conservation Program, Toronto Zoo, 361A Old Finch Avenue, Toronto, Ontario M1B 5K7, Canada
| | - Axel Janke
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberganlage 25, 60325 Frankfurt, Germany
- Senckenberg Biodiversity and Climate Research Centre, Senckenberganlage 25, 60325 Frankfurt am Main, Germany
| | - Burton K. Lim
- Department of Natural History, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario M5S 2C6, Canada
| | - Michael Hiller
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
- Goethe University, Faculty of Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberganlage 25, 60325 Frankfurt, Germany
- Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt, Germany
| |
Collapse
|
10
|
Yadav RP, Boyd K, Artemyev NO. Molecular insights into the maturation of phosphodiesterase 6 by the specialized chaperone complex of HSP90 with AIPL1. J Biol Chem 2022; 298:101620. [PMID: 35065964 PMCID: PMC8857470 DOI: 10.1016/j.jbc.2022.101620] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 12/18/2022] Open
Abstract
Phosphodiesterase 6 (PDE6) is a key effector enzyme in vertebrate phototransduction, and its maturation and function are known to critically depend on a specialized chaperone, aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1). Defects in PDE6 and AIPL1 underlie several severe retinal diseases, including retinitis pigmentosa and Leber congenital amaurosis. Here, we characterize the complex of AIPL1 with HSP90 and demonstrate its essential role in promoting the functional conformation of nascent PDE6. Our analysis suggests that AIPL1 preferentially binds to HSP90 in the closed state with a stoichiometry of 1:2, with the tetratricopeptide repeat domain and the tetratricopeptide repeat helix 7 extension of AIPL1 being the main contributors to the AIPL1/HSP90 interface. We demonstrate that mutations of these determinants markedly diminished both the affinity of AIPL1 for HSP90 and the ability of AIPL1 to cochaperone the maturation of PDE6 in a heterologous expression system. In addition, the FK506-binding protein (FKBP) domain of AIPL1 encloses a unique prenyl-binding site that anchors AIPL1 to posttranslational lipid modifications of PDE6. A mouse model with rod PDE6 lacking farnesylation of its PDE6A subunit revealed normal expression, trafficking, and signaling of the enzyme. Furthermore, AIPL1 was unexpectedly capable of inducing the maturation of unprenylated cone PDE6C, whereas mutant AIPL1 deficient in prenyl binding competently cochaperoned prenylated PDE6C. Thus, we conclude neither sequestration of the prenyl modifications is required for PDE6 maturation to proceed, nor is the FKBP-lipid interaction involved in the conformational switch of the enzyme into the functional state.
Collapse
Affiliation(s)
- Ravi P Yadav
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Kimberly Boyd
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.
| |
Collapse
|
11
|
Madeira C, Godinho G, Grangeia A, Falcão M, Silva R, Carneiro Â, Brandão E, Magalhães A, Falcão-Reis F, Estrela-Silva S. Two Novel Disease-Causing Variants in the PDE6C Gene Underlying Achromatopsia. Case Rep Ophthalmol 2021; 12:749-760. [PMID: 34720973 PMCID: PMC8460892 DOI: 10.1159/000512284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/10/2020] [Indexed: 12/03/2022] Open
Abstract
We report the clinical phenotype and genetic findings of two variants in PDE6C underlying achromatopsia (ACHM). Four patients with the variant c.1670G>A in exon 13 of the PDE6C gene were identified. Additionally, one had compound heterozygous genotype, with two variants in the PDE6C gene, a variant of c.2192G>A in exon 18 and c.1670G>A in exon 13. All patients presented the symptomatic triad of decreased visual acuity, severe photophobia, and colour vision disturbances. SD-OCT showed an absence of the ellipsoid zone, creating an optically empty cavity at the fovea in three patients. The patient with the compound heterozygous genotype presented a more severe subfoveal outer retina atrophy. ERG recordings showed extinguished responses under photopic and 30-Hz flicker stimulation, with a normal rod response. We identified two new variants in the PDE6C gene that leads to ACHM.
Collapse
Affiliation(s)
- Carolina Madeira
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal
| | - Gonçalo Godinho
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal
| | - Ana Grangeia
- Department of Genetics, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal
| | - Manuel Falcão
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal.,Department of Surgery and Physiology, Faculty of Medicine of University of Porto, Porto, Portugal
| | - Renato Silva
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal.,Department of Surgery and Physiology, Faculty of Medicine of University of Porto, Porto, Portugal
| | - Ângela Carneiro
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal.,Department of Surgery and Physiology, Faculty of Medicine of University of Porto, Porto, Portugal
| | - Elisete Brandão
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal
| | - Augusto Magalhães
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal
| | - Fernando Falcão-Reis
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal.,Department of Surgery and Physiology, Faculty of Medicine of University of Porto, Porto, Portugal
| | - Sérgio Estrela-Silva
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João Hospital, Porto, Portugal.,Department of Surgery and Physiology, Faculty of Medicine of University of Porto, Porto, Portugal
| |
Collapse
|
12
|
Kuehlewein L, Zobor D, Andreasson SO, Ayuso C, Banfi S, Bocquet B, Bernd AS, Biskup S, Boon CJF, Downes SM, Fischer MD, Holz FG, Kellner U, Leroy BP, Meunier I, Nasser F, Rosenberg T, Rudolph G, Stingl K, Thiadens AAHJ, Wilhelm B, Wissinger B, Zrenner E, Kohl S, Weisschuh N. Clinical Phenotype and Course of PDE6A-Associated Retinitis Pigmentosa Disease, Characterized in Preparation for a Gene Supplementation Trial. JAMA Ophthalmol 2021; 138:1241-1250. [PMID: 33057649 DOI: 10.1001/jamaophthalmol.2020.4206] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Importance Treatment trials require sound knowledge on the natural course of disease. Objective To assess clinical features, genetic findings, and genotype-phenotype correlations in patients with retinitis pigmentosa (RP) associated with biallelic sequence variations in the PDE6A gene in preparation for a gene supplementation trial. Design, Setting, and Participants This prospective, longitudinal, observational cohort study was conducted from January 2001 to December 2019 in a single center (Centre for Ophthalmology of the University of Tübingen, Germany) with patients recruited multinationally from 12 collaborating European tertiary referral centers. Patients with retinitis pigmentosa, sequence variants in PDE6A, and the ability to provide informed consent were included. Exposures Comprehensive ophthalmological examinations; validation of compound heterozygosity and biallelism by familial segregation analysis, allelic cloning, or assessment of next-generation sequencing-read data, where possible. Main Outcomes and Measures Genetic findings and clinical features describing the entire cohort and comparing patients harboring the 2 most common disease-causing variants in a homozygous state (c.304C>A;p.(R102S) and c.998 + 1G>A;p.?). Results Fifty-seven patients (32 female patients [56%]; mean [SD], 40 [14] years) from 44 families were included. All patients completed the study. Thirty patients were homozygous for disease-causing alleles. Twenty-seven patients were heterozygous for 2 different PDE6A variants each. The most frequently observed alleles were c.304C>A;p.(R102S), c.998 + 1G>A;p.?, and c.2053G>A;p.(V685M). The mean (SD) best-corrected visual acuity was 0.43 (0.48) logMAR (Snellen equivalent, 20/50). The median visual field area with object III4e was 660 square degrees (5th and 95th percentiles, 76 and 11 019 square degrees; 25th and 75th percentiles, 255 and 3923 square degrees). Dark-adapted and light-adapted full-field electroretinography showed no responses in 88 of 108 eyes (81.5%). Sixty-nine of 108 eyes (62.9%) showed additional findings on optical coherence tomography imaging (eg, cystoid macular edema or macular atrophy). The variant c.998 + 1G>A;p.? led to a more severe phenotype when compared with the variant c.304C>A;p.(R102S). Conclusions and Relevance Seventeen of the PDE6A variants found in these patients appeared to be novel. Regarding the clinical findings, disease was highly symmetrical between the right and left eyes and visual impairment was mild or moderate in 90% of patients, providing a window of opportunity for gene therapy.
Collapse
Affiliation(s)
- Laura Kuehlewein
- Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard Karls University Tübingen, Germany.,University Eye Hospital, Centre for Ophthalmology, Eberhard Karls University Tübingen, Germany
| | - Ditta Zobor
- Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard Karls University Tübingen, Germany
| | - Sten Olof Andreasson
- Lund University, Skane University Hospital, Department of Ophthalmology, Lund, Sweden
| | - Carmen Ayuso
- Department of Genetics, IIS-Fundación Jiménez Díaz-University Hospital; Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Research on Rare Diseases, Madrid, Spain
| | - Sandro Banfi
- Telethon Institute of Genetics and Medicine, Pozzuoli (NA) and Medical Genetics, Department of Precision Medicine, University of Campania "Luigi Vanvitelli," Naples, Italy
| | - Beatrice Bocquet
- Institute for Neurosciences of Montpellier Unité 1051, University of Montpellier, Montpellier, France.,National Center for Rare Diseases, Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Antje S Bernd
- University Eye Hospital, Centre for Ophthalmology, Eberhard Karls University Tübingen, Germany
| | | | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Leiden University, Leiden, the Netherlands.,Department of Ophthalmology, Amsterdam University Medical Centers, Amsterdam, the Netherlands
| | - Susan M Downes
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
| | - M Dominik Fischer
- Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard Karls University Tübingen, Germany.,University Eye Hospital, Centre for Ophthalmology, Eberhard Karls University Tübingen, Germany
| | - Frank G Holz
- Department of Ophthalmology, University of Bonn, Germany
| | - Ulrich Kellner
- Rare Retinal Disease Center, AugenZentrum Siegburg, MVZ Augenärztliches Diagnostik- und Therapiecentrum GmbH, Siegburg, Germany.,RetinaScience, Bonn, Germany
| | - Bart P Leroy
- Department of Ophthalmology Ghent University Hospital, Ghent, Belgium.,Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.,Division of Ophthalmology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Center for Cellular & Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Isabelle Meunier
- Institute for Neurosciences of Montpellier Unité 1051, University of Montpellier, Montpellier, France.,National Center for Rare Diseases, Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Fadi Nasser
- Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard Karls University Tübingen, Germany
| | - Thomas Rosenberg
- Department of Ophthalmology, Kennedy Center, Rigshospitalet, Copenhagen, Denmark
| | - Günther Rudolph
- Ophthalmogenetik, Augenklinik, Klinikum der Universität München, Munich, Germany
| | - Katarina Stingl
- University Eye Hospital, Centre for Ophthalmology, Eberhard Karls University Tübingen, Germany
| | | | - Barbara Wilhelm
- STZ Eyetrial, Centre for Ophthalmology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Eberhart Zrenner
- Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard Karls University Tübingen, Germany.,Werner Reichardt Centre for Integrative Neuroscience, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Nicole Weisschuh
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard Karls University Tübingen, Tübingen, Germany
| | | |
Collapse
|
13
|
Daich Varela M, Ullah E, Yousaf S, Brooks BP, Hufnagel RB, Huryn LA. PDE6C: Novel Mutations, Atypical Phenotype, and Differences Among Children and Adults. Invest Ophthalmol Vis Sci 2021; 61:1. [PMID: 33001157 PMCID: PMC7545085 DOI: 10.1167/iovs.61.12.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Purpose Genetic variation in PDE6C is associated with achromatopsia and cone dystrophy, with only a few reports of cone-rod dystrophy in the literature. We describe two pediatric and two adult patients with PDE6C related cone and cone-rod dystrophy and the first longitudinal data of a pediatric patient with PDE6C-related cone dystrophy. Methods This cohort of four patients underwent comprehensive ophthalmologic evaluation at the National Eye Institute's Ophthalmic Genetics clinic, including visual field testing, retinal imaging and electroretinogram (ERG). Next-generation sequencing-based genetic testing was performed and subsequent analysis of the variants was done through three-dimensional protein models generated by Phyre2 and Chimera. Results All cases shared decreased best-corrected visual acuity and poor color discrimination. Three of the four patients had a cone-rod dystrophy, presenting with an ERG showing decreased amplitude on both photopic and scotopic waveforms and a mild to moderately constricted visual field. One of the children was diagnosed with cone dystrophy, having a preserved peripheral field. The children had none to minor structural retinal changes, whereas the adults had clear macular dystrophy. Conclusions PDE6C-related cone-rod dystrophy consists of a severe phenotype characterized by early-onset nystagmus, decreased best-corrected visual acuity, poor color discrimination, progressive constriction of the visual field, and night blindness. Our work contributes with valuable information toward understanding the visual prognosis and allelic heterogeneity of PDE6C-related cone and cone-rod dystrophy.
Collapse
Affiliation(s)
- Malena Daich Varela
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Ehsan Ullah
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Sairah Yousaf
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Brian P Brooks
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Robert B Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Laryssa A Huryn
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| |
Collapse
|
14
|
The PDE-Opathies: Diverse Phenotypes Produced by a Functionally Related Multigene Family. Trends Genet 2021; 37:669-681. [PMID: 33832760 DOI: 10.1016/j.tig.2021.03.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/07/2021] [Accepted: 03/09/2021] [Indexed: 12/30/2022]
Abstract
The phosphodiesterase (PDE)-opathies, an expanding set of disorders caused by germline mutations in cyclic nucleotide PDEs, present an intriguing paradox. The enzymes encoded by the PDE family all hydrolyze cAMP and/or cGMP, but mutations in different family members produce very divergent phenotypes. Three interacting factors have been shown recently to contribute to this phenotypic diversity: (i) the 21 genes encode over 80 different isoforms, using alternative mRNA splicing and related mechanisms; (ii) the various isoforms have different regulatory mechanisms, mediated by their unique amino-terminal regulatory domains; (iii) the isoforms differ widely in their pattern of tissue expression. These mechanisms explain why many PDE-opathies are gain-of-function mutations and how they exemplify uniqueness and redundancy within a multigene family.
Collapse
|
15
|
Georgiou M, Singh N, Kane T, Zaman S, Hirji N, Aboshiha J, Kumaran N, Kalitzeos A, Carroll J, Weleber RG, Michaelides M. Long-Term Investigation of Retinal Function in Patients with Achromatopsia. Invest Ophthalmol Vis Sci 2021; 61:38. [PMID: 32960951 PMCID: PMC7509756 DOI: 10.1167/iovs.61.11.38] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate the long-term natural history of retinal function of achromatopsia (ACHM). Methods Subjects with molecularly confirmed ACHM were recruited in a prospective cohort study of mesopic microperimetry. Coefficient of repeatability and intraclass correlation coefficient (ICC) of mean sensitivity (MS) were calculated. Best-corrected visual acuity (BCVA), bivariate contour ellipse area (BCEA), contrast sensitivity (CS), MS, total volume (VTOT), and central field volume (V5°) from volumetric and topographic analyses were acquired. Correlation of functional parameters with structural findings from optical coherence tomography (OCT) was performed. Results Eighteen subjects were recruited. Mean follow-up was 7.2 years. The MS test–retest repeatability coefficient was 1.65 decibels (dB), and the ICC was 0.973 (95% confidence interval, 0.837–0.98). Mean MS was similar for right and left eyes (16.97dB and 17.14dB, respectively). A negative significant correlation between logMAR BCVA and the retinal sensitivity indices (MS, VTOT, V5°) was found. A significant negative correlation between logCS and MS, VTOT, and V5° was also observed. BCVA and BCEA improved during follow-up. Mean CS, MS, VTOT, and V5° at final follow-up were similar to baseline. MS was similar between CNGA3- and CNGB3-ACHM. Patients with and without the presence of a foveal ellipsoid zone on OCT had similar MS (16.64 dB and 17.17 dB, respectively). Conclusions We demonstrate a highly reproducible assessment of MS. Retinal function including MS, volumetric indices, and CS are stable in ACHM. Improvement of fixation stability and small changes of BCVA over time may be part of the natural history of the disease.
Collapse
Affiliation(s)
- Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| | - Navjit Singh
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| | - Thomas Kane
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| | - Serena Zaman
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| | - Nashila Hirji
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| | - Jonathan Aboshiha
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Neruban Kumaran
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| | - Angelos Kalitzeos
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| | - Joseph Carroll
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Wauwatosa, Wisconsin, United States
| | - Richard G Weleber
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| |
Collapse
|
16
|
Georgiou M, Fujinami K, Michaelides M. Inherited retinal diseases: Therapeutics, clinical trials and end points-A review. Clin Exp Ophthalmol 2021; 49:270-288. [PMID: 33686777 DOI: 10.1111/ceo.13917] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/22/2021] [Accepted: 03/01/2021] [Indexed: 12/18/2022]
Abstract
Inherited retinal diseases (IRDs) are a clinically and genetically heterogeneous group of disorders characterised by photoreceptor degeneration or dysfunction. These disorders typically present with severe vision loss that can be progressive, with disease onset ranging from congenital to late adulthood. The advances in genetics, retinal imaging and molecular biology, have conspired to create the ideal environment for establishing treatments for IRDs, with the first approved gene therapy and the commencement of multiple clinical trials. The scope of this review is to familiarise clinicians and scientists with the current management and the prospects for novel therapies for: (1) macular dystrophies, (2) cone and cone-rod dystrophies, (3) cone dysfunction syndromes, (4) Leber congenital amaurosis, (5) rod-cone dystrophies, (6) rod dysfunction syndromes and (7) chorioretinal dystrophies. We also briefly summarise the investigated end points for the ongoing trials.
Collapse
Affiliation(s)
- Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Kaoru Fujinami
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK.,Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| |
Collapse
|
17
|
Gupta R, Liu Y, Wang H, Nordyke CT, Puterbaugh RZ, Cui W, Varga K, Chu F, Ke H, Vashisth H, Cote RH. Structural Analysis of the Regulatory GAF Domains of cGMP Phosphodiesterase Elucidates the Allosteric Communication Pathway. J Mol Biol 2020; 432:5765-5783. [PMID: 32898583 PMCID: PMC7572642 DOI: 10.1016/j.jmb.2020.08.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 12/26/2022]
Abstract
Regulation of photoreceptor phosphodiesterase (PDE6) activity is responsible for the speed, sensitivity, and recovery of the photoresponse during visual signaling in vertebrate photoreceptor cells. It is hypothesized that physiological differences in the light responsiveness of rods and cones may result in part from differences in the structure and regulation of the distinct isoforms of rod and cone PDE6. Although rod and cone PDE6 catalytic subunits share a similar domain organization consisting of tandem GAF domains (GAFa and GAFb) and a catalytic domain, cone PDE6 is a homodimer whereas rod PDE6 consists of two homologous catalytic subunits. Here we provide the x-ray crystal structure of cone GAFab regulatory domain solved at 3.3 Å resolution, in conjunction with chemical cross-linking and mass spectrometric analysis of conformational changes to GAFab induced upon binding of cGMP and the PDE6 inhibitory γ-subunit (Pγ). Ligand-induced changes in cross-linked residues implicate multiple conformational changes in the GAFa and GAFb domains in forming an allosteric communication network. Molecular dynamics simulations of cone GAFab revealed differences in conformational dynamics of the two subunits forming the homodimer and allosteric perturbations on cGMP binding. Cross-linking of Pγ to GAFab in conjunction with solution NMR spectroscopy of isotopically labeled Pγ identified the central polycationic region of Pγ interacting with the GAFb domain. These results provide a mechanistic basis for developing allosteric activators of PDE6 with therapeutic implications for halting the progression of several retinal degenerative diseases.
Collapse
Affiliation(s)
- Richa Gupta
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, 46 College Rd., Durham, NH 03824, USA
| | - Yong Liu
- Department of Chemical Engineering, University of New Hampshire, 33 Academic Way, Durham, NH 03824, USA
| | - Huanchen Wang
- Signal Transduction Laboratory, NIEHS/NIH, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Christopher T Nordyke
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, 46 College Rd., Durham, NH 03824, USA
| | - Ryan Z Puterbaugh
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, 46 College Rd., Durham, NH 03824, USA
| | - Wenjun Cui
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Krisztina Varga
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, 46 College Rd., Durham, NH 03824, USA
| | - Feixia Chu
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, 46 College Rd., Durham, NH 03824, USA
| | - Hengming Ke
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, 33 Academic Way, Durham, NH 03824, USA
| | - Rick H Cote
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, 46 College Rd., Durham, NH 03824, USA.
| |
Collapse
|
18
|
Sun W, Li S, Xiao X, Wang P, Zhang Q. Genotypes and phenotypes of genes associated with achromatopsia: A reference for clinical genetic testing. Mol Vis 2020; 26:588-602. [PMID: 32913385 PMCID: PMC7479066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 08/20/2020] [Indexed: 11/23/2022] Open
Abstract
PURPOSE Achromatopsia is a congenital autosomal recessive cone disorder, and it has been found to be associated with six genes. However, pathogenic variants in these six genes have been identified in patients with various retinal dystrophies with the exception of achromatopsia. Thus, this study aims to investigate the contribution of these genes in hereditary retinal diseases and the potential genotype-phenotype correlations. METHODS Biallelic variants in six achromatopsia-related genes, namely, CNGA3, CNGB3, GNAT2, ATF6, PDE6C, and PDE6H, were analyzed based on data obtained from 7,195 probands with different eye conditions. A systematic genotype-phenotype analysis of these genes was performed based on these data, along with the data reported in the literature. RESULTS Biallelic potential pathogenic variants (PPVs) in five of the six genes were identified in 119 probands with genetic eye diseases. The variants in CNGA3 were the most common and accounted for 81.5% (97/119). Of the 119 probands, 62.2% (74/119) have cone-rod dystrophy, whereas only 25.2% (30/119) have achromatopsia. No biallelic pathogenic variants in these genes were identified in patients with rod-dominant degeneration. A systematic review of genotypes and phenotypes revealed certain characteristics of each of the six genes, providing clues for the pathogenicity evaluation of the variants of the genes. CONCLUSIONS PPVs in the six genes were identified in various inherited retinal degeneration diseases, most of which are cone-dominant diseases but no rod-dominant diseases based on the data from a cohort of 7,195 probands with different eye conditions. The systematic genotype-phenotype analysis of these genes will be useful in drafting guidelines for the clinical genetic diagnostic application for the investigated genes.
Collapse
|
19
|
Georgiou M, Robson AG, Singh N, Pontikos N, Kane T, Hirji N, Ripamonti C, Rotsos T, Dubra A, Kalitzeos A, Webster AR, Carroll J, Michaelides M. Deep Phenotyping of PDE6C-Associated Achromatopsia. Invest Ophthalmol Vis Sci 2019; 60:5112-5123. [PMID: 31826238 PMCID: PMC6905659 DOI: 10.1167/iovs.19-27761] [Citation(s) in RCA: 45] [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: 06/14/2019] [Accepted: 10/23/2019] [Indexed: 11/29/2022] Open
Abstract
Purpose To perform deep phenotyping of subjects with PDE6C achromatopsia and examine disease natural history. Methods Eight subjects with disease-causing variants in PDE6C were assessed in detail, including clinical phenotype, best-corrected visual acuity, fundus autofluorescence, and optical coherence tomography. Six subjects also had confocal and nonconfocal adaptive optics scanning light ophthalmoscopy, axial length, international standard pattern and full-field electroretinography (ERG), short-wavelength flash (S-cone) ERGs, and color vision testing. Results All subjects presented with early-onset nystagmus, decreased best-corrected visual acuity, light sensitivity, and severe color vision loss, and five of them had high myopia. We identified three novel disease-causing variants and provide phenotype data associated with nine variants for the first time. No subjects had foveal hypoplasia or residual ellipsoid zone (EZ) at the foveal center; one had an absent EZ, three had a hyporeflective zone, and four had outer retinal atrophy. The mean width of the central EZ lesion on optical coherence tomography at baseline was 1923 μm. The mean annual increase in EZ lesion size was 48.3 μm. Fundus autofluorescence revealed a central hypoautofluorescence with a surrounding ring of increased signal (n = 5). The mean hypoautofluorescent area at baseline was 3.33 mm2 and increased in size by a mean of 0.13 mm2/year. Nonconfocal adaptive optics scanning light ophthalmoscopy revealed residual foveal cones in only one of two cases. Full-field ERGs were consistent with severe generalized cone system dysfunction but with relative preservation of S-cone sensitivity. Conclusions PDE6C retinopathy is a severe cone dysfunction syndrome often presenting as typical achromatopsia but without foveal hypoplasia. Myopia and slowly progressive maculopathy are common features. There are few (if any) residual foveal cones for intervention in older adults.
Collapse
Affiliation(s)
- Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, City Road, London, United Kingdom
| | - Anthony G. Robson
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, City Road, London, United Kingdom
| | - Navjit Singh
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, City Road, London, United Kingdom
| | - Nikolas Pontikos
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, City Road, London, United Kingdom
| | - Thomas Kane
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, City Road, London, United Kingdom
| | - Nashila Hirji
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, City Road, London, United Kingdom
| | | | - Tryfon Rotsos
- First Division of Ophthalmology, National and Kapodistrian University of Athens, General Hospital of Athens, Athens, Greece
| | - Alfredo Dubra
- Department of Ophthalmology, Stanford University, Palo Alto, California, United States
| | - Angelos Kalitzeos
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, City Road, London, United Kingdom
| | - Andrew R. Webster
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, City Road, London, United Kingdom
| | - Joseph Carroll
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, City Road, London, United Kingdom
| |
Collapse
|
20
|
Domingo-Prim J, Abad-Morales V, Riera M, Navarro R, Corcostegui B, Pomares E. Generation of an induced pluripotent stem cell line (FRIMOi007-A) derived from an incomplete achromatopsia patient carrying a novel homozygous mutation in PDE6C gene. Stem Cell Res 2019; 40:101569. [PMID: 31520890 DOI: 10.1016/j.scr.2019.101569] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 08/19/2019] [Accepted: 09/03/2019] [Indexed: 11/17/2022] Open
Abstract
Incomplete achromatopsia (ACHM) is a disorder in which there is function defect of cone photoreceptors in the retina and individuals with such disease retain residual color vision. Here, we have generated an induced pluripotent stem cell (iPSC) line carrying a homozygous mutation in the PDE6C gene, already related with this vision disorder. Skin fibroblasts from a patient with incomplete ACHM were reprogrammed to iPSCs by the non-integrative Sendai-virus method. Finally, the iPSC line has been characterized expressing the pluripotency markers and being capable to differentiate to endoderm, mesoderm and ectoderm in vitro.
Collapse
Affiliation(s)
- Judit Domingo-Prim
- Fundació de Recerca de l'Institut de Microcirurgia Ocular, Barcelona, Spain; Departament de Genètica, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Víctor Abad-Morales
- Fundació de Recerca de l'Institut de Microcirurgia Ocular, Barcelona, Spain; Departament de Genètica, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Marina Riera
- Fundació de Recerca de l'Institut de Microcirurgia Ocular, Barcelona, Spain; Departament de Genètica, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Rafael Navarro
- Fundació de Recerca de l'Institut de Microcirurgia Ocular, Barcelona, Spain; Departament de Retina, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Borja Corcostegui
- Fundació de Recerca de l'Institut de Microcirurgia Ocular, Barcelona, Spain; Departament de Retina, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Esther Pomares
- Fundació de Recerca de l'Institut de Microcirurgia Ocular, Barcelona, Spain; Departament de Genètica, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain.
| |
Collapse
|
21
|
Yadav RP, Boyd K, Yu L, Artemyev NO. Interaction of the tetratricopeptide repeat domain of aryl hydrocarbon receptor-interacting protein-like 1 with the regulatory Pγ subunit of phosphodiesterase 6. J Biol Chem 2019; 294:15795-15807. [PMID: 31488544 DOI: 10.1074/jbc.ra119.010666] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/03/2019] [Indexed: 12/13/2022] Open
Abstract
Phosphodiesterase-6 (PDE6) is key to both phototransduction and health of rods and cones. Proper folding of PDE6 relies on the chaperone activity of aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1), and mutations in both PDE6 and AIPL1 can cause a severe form of blindness. Although AIPL1 and PDE6 are known to interact via the FK506-binding protein domain of AIPL1, the contribution of the tetratricopeptide repeat (TPR) domain of AIPL1 to its chaperone function is poorly understood. Here, we demonstrate that AIPL1-TPR interacts specifically with the regulatory Pγ subunit of PDE6. Use of NMR chemical shift perturbation (CSP) mapping technique revealed the interface between the C-terminal portion of Pγ and AIPL1-TPR. Our solution of the crystal structure of the AIPL1-TPR domain provided additional information, which together with the CSP data enabled us to generate a model of this interface. Biochemical analysis of chimeric AIPL1-AIP proteins supported this model and also revealed a correlation between the affinity of AIPL1-TPR for Pγ and the ability of Pγ to potentiate the chaperone activity of AIPL1. Based on these results, we present a model of the larger AIPL1-PDE6 complex. This supports the importance of simultaneous interactions of AIPL1-FK506-binding protein with the prenyl moieties of PDE6 and AIPL1-TPR with the Pγ subunit during the folding and/or assembly of PDE6. This study sheds new light on the versatility of TPR domains in protein folding by describing a novel TPR-protein binding partner, Pγ, and revealing that this subunit imparts AIPL1 selectivity for its client.
Collapse
Affiliation(s)
- Ravi P Yadav
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - Kimberly Boyd
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - Liping Yu
- Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242.,NMR Core Facility, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242 .,Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| |
Collapse
|
22
|
Power M, Das S, Schütze K, Marigo V, Ekström P, Paquet-Durand F. Cellular mechanisms of hereditary photoreceptor degeneration - Focus on cGMP. Prog Retin Eye Res 2019; 74:100772. [PMID: 31374251 DOI: 10.1016/j.preteyeres.2019.07.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 07/25/2019] [Accepted: 07/29/2019] [Indexed: 12/21/2022]
Abstract
The cellular mechanisms underlying hereditary photoreceptor degeneration are still poorly understood, a problem that is exacerbated by the enormous genetic heterogeneity of this disease group. However, the last decade has yielded a wealth of new knowledge on degenerative pathways and their diversity. Notably, a central role of cGMP-signalling has surfaced for photoreceptor cell death triggered by a subset of disease-causing mutations. In this review, we examine key aspects relevant for photoreceptor degeneration of hereditary origin. The topics covered include energy metabolism, epigenetics, protein quality control, as well as cGMP- and Ca2+-signalling, and how the related molecular and metabolic processes may trigger photoreceptor demise. We compare and integrate evidence on different cell death mechanisms that have been associated with photoreceptor degeneration, including apoptosis, necrosis, necroptosis, and PARthanatos. A special focus is then put on the mechanisms of cGMP-dependent cell death and how exceedingly high photoreceptor cGMP levels may cause activation of Ca2+-dependent calpain-type proteases, histone deacetylases and poly-ADP-ribose polymerase. An evaluation of the available literature reveals that a large group of patients suffering from hereditary photoreceptor degeneration carry mutations that are likely to trigger cGMP-dependent cell death, making this pathway a prime target for future therapy development. Finally, an outlook is given into technological and methodological developments that will with time likely contribute to a comprehensive overview over the entire metabolic complexity of photoreceptor cell death. Building on such developments, new imaging technology and novel biomarkers may be used to develop clinical test strategies, that fully consider the genetic heterogeneity of hereditary retinal degenerations, in order to facilitate clinical testing of novel treatment approaches.
Collapse
Affiliation(s)
- Michael Power
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Germany; Centre for Integrative Neurosciences (CIN), University of Tübingen, Germany; Graduate Training Centre of Neuroscience (GTC), University of Tübingen, Germany
| | - Soumyaparna Das
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Germany; Graduate Training Centre of Neuroscience (GTC), University of Tübingen, Germany
| | | | - Valeria Marigo
- Department of Life Sciences, University of Modena and Reggio Emilia, Italy
| | - Per Ekström
- Ophthalmology, Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, Sweden
| | - François Paquet-Durand
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Germany.
| |
Collapse
|
23
|
Tobias P, Philipp SI, Stylianos M, Martin B, Barbara W, Felix R, Alexander OG, Eberhart Z, Marius U, Birgit K, Sven K, Ulrich BSK, Dominik FM, Bartz-Schmidt KU, Bolz S, Fischer D, Kohl S, Kühlewein L, Mühlfriedel R, Neubauer J, Ochakovski A, Paquet-Durand F, Seeliger M, Sothilingam V, Ueffing M, Weisschuh N, Wissinger B, Zhour A, Zobor D, Zrenner E, Biel M, Michalakis S, Schön C, Kahle N, Peters T, Wilhelm B, Tsang S, Glöckner CJ. Safety and Toxicology of Ocular Gene Therapy with Recombinant AAV Vector rAAV.hCNGA3 in Nonhuman Primates. HUM GENE THER CL DEV 2019; 30:50-56. [DOI: 10.1089/humc.2018.188] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Peters Tobias
- University Eye Hospital Tübingen, University of Tübingen, Tübingen, Germany
- STZ Eyetrial, University of Tübingen, Tübingen, Germany
| | | | - Michalakis Stylianos
- Center for Integrated Protein Science Munich, Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of Munich, Munich, Germany
| | - Biel Martin
- Center for Integrated Protein Science Munich, Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of Munich, Munich, Germany
| | | | - Reichel Felix
- University Eye Hospital Tübingen, University of Tübingen, Tübingen, Germany
| | | | - Zrenner Eberhart
- Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ueffing Marius
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | | | - Korte Sven
- Covance Preclinical Services GmbH, Münster, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Moshiri A, Chen R, Kim S, Harris RA, Li Y, Raveendran M, Davis S, Liang Q, Pomerantz O, Wang J, Garzel L, Cameron A, Yiu G, Stout JT, Huang Y, Murphy CJ, Roberts J, Gopalakrishna KN, Boyd K, Artemyev NO, Rogers J, Thomasy SM. A nonhuman primate model of inherited retinal disease. J Clin Invest 2019; 129:863-874. [PMID: 30667376 PMCID: PMC6355306 DOI: 10.1172/jci123980] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 11/15/2018] [Indexed: 12/30/2022] Open
Abstract
Inherited retinal degenerations are a common cause of untreatable blindness worldwide, with retinitis pigmentosa and cone dystrophy affecting approximately 1 in 3500 and 1 in 10,000 individuals, respectively. A major limitation to the development of effective therapies is the lack of availability of animal models that fully replicate the human condition. Particularly for cone disorders, rodent, canine, and feline models with no true macula have substantive limitations. By contrast, the cone-rich macula of a nonhuman primate (NHP) closely mirrors that of the human retina. Consequently, well-defined NHP models of heritable retinal diseases, particularly cone disorders that are predictive of human conditions, are necessary to more efficiently advance new therapies for patients. We have identified 4 related NHPs at the California National Primate Research Center with visual impairment and findings from clinical ophthalmic examination, advanced retinal imaging, and electrophysiology consistent with achromatopsia. Genetic sequencing confirmed a homozygous R565Q missense mutation in the catalytic domain of PDE6C, a cone-specific phototransduction enzyme associated with achromatopsia in humans. Biochemical studies demonstrate that the mutant mRNA is translated into a stable protein that displays normal cellular localization but is unable to hydrolyze cyclic GMP (cGMP). This NHP model of a cone disorder will not only serve as a therapeutic testing ground for achromatopsia gene replacement, but also for optimization of gene editing in the macula and of cone cell replacement in general.
Collapse
Affiliation(s)
- Ala Moshiri
- Department of Ophthalmology & Vision Science, School of Medicine, UC Davis, Sacramento, California, USA
| | - Rui Chen
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, and.,Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - R Alan Harris
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, and
| | - Yumei Li
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, and
| | | | - Sarah Davis
- California National Primate Research Center, Davis, California, USA
| | - Qingnan Liang
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Ori Pomerantz
- California National Primate Research Center, Davis, California, USA
| | - Jun Wang
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, and
| | - Laura Garzel
- California National Primate Research Center, Davis, California, USA
| | - Ashley Cameron
- California National Primate Research Center, Davis, California, USA
| | - Glenn Yiu
- Department of Ophthalmology & Vision Science, School of Medicine, UC Davis, Sacramento, California, USA
| | - J Timothy Stout
- Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA
| | | | - Christopher J Murphy
- Department of Ophthalmology & Vision Science, School of Medicine, UC Davis, Sacramento, California, USA.,Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA.,EyeKor Inc., Madison, Wisconsin, USA
| | - Jeffrey Roberts
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA.,California National Primate Research Center, Davis, California, USA
| | | | - Kimberly Boyd
- Department of Molecular Physiology and Biophysics, and
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, and.,Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Jeffrey Rogers
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, and
| | - Sara M Thomasy
- Department of Ophthalmology & Vision Science, School of Medicine, UC Davis, Sacramento, California, USA.,Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| |
Collapse
|
25
|
Sokolov M, Yadav RP, Brooks C, Artemyev NO. Chaperones and retinal disorders. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2018; 114:85-117. [PMID: 30635087 DOI: 10.1016/bs.apcsb.2018.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Defects in protein folding and trafficking are a common cause of photoreceptor degeneration, causing blindness. Photoreceptor cells present an unusual challenge to the protein folding and transport machinery due to the high rate of protein synthesis, trafficking and the renewal of the outer segment, a primary cilium that has been modified into a specialized light-sensing compartment. Phototransduction components, such as rhodopsin and cGMP-phosphodiesterase, and multimeric ciliary transport complexes, such as the BBSome, are hotspots for mutations that disrupt proteostasis and lead to the death of photoreceptors. In this chapter, we review recent studies that advance our understanding of the chaperone and transport machinery of phototransduction proteins.
Collapse
Affiliation(s)
- Maxim Sokolov
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | - Ravi P Yadav
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Celine Brooks
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA, United States.
| |
Collapse
|
26
|
Weisschuh N, Stingl K, Audo I, Biskup S, Bocquet B, Branham K, Burstedt MS, De Baere E, De Vries MJ, Golovleva I, Green A, Heckenlively J, Leroy BP, Meunier I, Traboulsi E, Wissinger B, Kohl S. Mutations in the gene PDE6C encoding the catalytic subunit of the cone photoreceptor phosphodiesterase in patients with achromatopsia. Hum Mutat 2018; 39:1366-1371. [PMID: 30080950 DOI: 10.1002/humu.23606] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/24/2018] [Accepted: 08/02/2018] [Indexed: 12/22/2022]
Abstract
Biallelic PDE6C mutations are a known cause for rod monochromacy, better known as autosomal recessive achromatopsia (ACHM), and early-onset cone photoreceptor dysfunction. PDE6C encodes the catalytic α'-subunit of the cone photoreceptor phosphodiesterase, thereby constituting an essential part of the phototransduction cascade. Here, we present the results of a study comprising 176 genetically preselected patients who remained unsolved after Sanger sequencing of the most frequent genes accounting for ACHM, and were subsequently screened for exonic and splice site variants in PDE6C applying a targeted next generation sequencing approach. We were able to identify potentially pathogenic biallelic variants in 15 index cases. The mutation spectrum comprises 18 different alleles, 15 of which are novel. Our study significantly contributes to the mutation spectrum of PDE6C and allows for a realistic estimate of the prevalence of PDE6C mutations in ACHM since our entire ACHM cohort comprises 1,074 independent families.
Collapse
Affiliation(s)
- Nicole Weisschuh
- Institute for Ophthalmic Research, Centre for Ophthalmology, University Tuebingen, Tuebingen, Germany
| | - Katarina Stingl
- Institute for Ophthalmic Research, Centre for Ophthalmology, University Tuebingen, Tuebingen, Germany
| | - Isabelle Audo
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France
| | - Saskia Biskup
- CeGaT GmbH and Praxis fuer Humangenetik Tuebingen, Tuebingen, Germany
| | - Béatrice Bocquet
- Institute for Neurosciences of Montpellier INSERM U1051, University of Montpellier, Montpellier, France.,National Center for Rare Genetic Retinal Dystrophies, Hopital Gui de Chauliac, Montpellier, France
| | - Kari Branham
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan
| | - Marie S Burstedt
- Department of Clinical Sciences/Ophthalmology, University of Umea, Umea, Sweden
| | - Elfride De Baere
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Meindert J De Vries
- Department of Ophthalmology, Childrens' Hospital Queen Fabiola (Huderf), Brussels, Belgium
| | - Irina Golovleva
- Department of Medical Biosciences/Medical and Clinical Genetics, University of Umea, Umea, Sweden
| | - Andrew Green
- Department of Clinical Genetics, Our Lady's Hospital, Crumlin, Dublin, Ireland.,School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - John Heckenlively
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan
| | - Bart P Leroy
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium.,Ophthalmic Genetics & Visual Electrophysiology, Division of Ophthalmology & Center for Cellular & Molecular Therapy, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Department of Ophthalmology, Ghent University Hospital & Ghent University, Ghent, Belgium
| | - Isabelle Meunier
- Institute for Neurosciences of Montpellier INSERM U1051, University of Montpellier, Montpellier, France.,National Center for Rare Genetic Retinal Dystrophies, Hopital Gui de Chauliac, Montpellier, France
| | | | - Bernd Wissinger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University Tuebingen, Tuebingen, Germany
| | - Susanne Kohl
- Institute for Ophthalmic Research, Centre for Ophthalmology, University Tuebingen, Tuebingen, Germany
| |
Collapse
|
27
|
Yadav RP, Artemyev NO. AIPL1: A specialized chaperone for the phototransduction effector. Cell Signal 2017; 40:183-189. [PMID: 28939106 PMCID: PMC6022367 DOI: 10.1016/j.cellsig.2017.09.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 09/11/2017] [Accepted: 09/18/2017] [Indexed: 12/12/2022]
Abstract
Molecular chaperones play pivotal roles in protein folding, quality control, assembly of multimeric protein complexes, protein trafficking, stress responses, and other essential cellular processes. Retinal photoreceptor rod and cone cells have an unusually high demand for production, quality control, and trafficking of key phototransduction components, and thus, require a robust and specialized chaperone machinery to ensure the fidelity of sensing and transmission of visual signals. Misfolding and/or mistrafficking of photoreceptor proteins are known causes for debilitating blinding diseases. Phosphodiesterase 6, the effector enzyme of the phototransduction cascade, relies on a unique chaperone aryl hydrocarbon receptor (AhR)-interacting protein-like 1 (AIPL1) for its stability and function. The structure of AIPL1 and its relationship with the client remained obscure until recently. This review summarizes important recent advances in understanding the mechanisms underlying normal function of AIPL1 and the protein perturbations caused by pathogenic mutations.
Collapse
Affiliation(s)
- Ravi P Yadav
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States.
| |
Collapse
|
28
|
Gopalakrishna KN, Boyd K, Artemyev NO. Mechanisms of mutant PDE6 proteins underlying retinal diseases. Cell Signal 2017; 37:74-80. [PMID: 28583373 DOI: 10.1016/j.cellsig.2017.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 05/30/2017] [Accepted: 06/01/2017] [Indexed: 12/15/2022]
Abstract
Mutations in PDE6 genes encoding the effector enzymes in rods and cones underlie severe retinal diseases including retinitis pigmentosa (RP), autosomal dominant congenital stationary night blindness (adCSNB), and achromatopsia (ACHM). Here we examined a spectrum of pathogenic missense mutations in PDE6 using the system based on co-expression of cone PDE6C with its specialized chaperone AIPL1 and the regulatory Pγ subunit as a potent co-chaperone. We uncovered two mechanisms of PDE6C mutations underlying ACHM: (a) folding defects leading to expression of catalytically inactive proteins and (b) markedly diminished ability of Pγ to co-chaperone mutant PDE6C proteins thereby dramatically reducing the levels of functional enzyme. The mechanism of the Rambusch adCSNB associated with the H258N substitution in PDE6B was probed through the analysis of the model mutant PDE6C-H262N. We identified two interrelated deficits of PDE6C-H262N: disruption of the inhibitory interaction of Pγ with mutant PDE6C that markedly reduced the ability of Pγ to augment the enzyme folding. Thus, we conclude that the Rambusch adCSNB is triggered by low levels of the constitutively active PDE6. Finally, we examined PDE6C-L858V, which models PDE6B-L854V, an RP-linked mutation that alters the protein isoprenyl modification. This analysis suggests that the type of prenyl modifications does not impact the folding of PDE6, but it modulates the enzyme affinity for its trafficking partner PDE6D. Hence, the pathogenicity of PDE6B-L854V likely arises from its trafficking deficiency. Taken together, our results demonstrate the effectiveness of the PDE6C expression system to evaluate pathogenicity and elucidate the mechanisms of PDE6 mutations in retinal diseases.
Collapse
MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Color Vision Defects/genetics
- Color Vision Defects/metabolism
- Cyclic Nucleotide Phosphodiesterases, Type 6/analysis
- Cyclic Nucleotide Phosphodiesterases, Type 6/genetics
- Cyclic Nucleotide Phosphodiesterases, Type 6/metabolism
- Eye Diseases, Hereditary/genetics
- Eye Diseases, Hereditary/metabolism
- Eye Proteins/analysis
- Eye Proteins/genetics
- Eye Proteins/metabolism
- Gene Expression
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/metabolism
- HEK293 Cells
- Humans
- Mice
- Models, Molecular
- Mutation, Missense
- Myopia/genetics
- Myopia/metabolism
- Night Blindness/genetics
- Night Blindness/metabolism
- Protein Folding
- Protein Prenylation
- Retinal Diseases/genetics
- Retinal Diseases/metabolism
Collapse
Affiliation(s)
- Kota N Gopalakrishna
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States
| | - Kimberly Boyd
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States.
| |
Collapse
|
29
|
Gopalakrishna KN, Boyd K, Yadav RP, Artemyev NO. Aryl Hydrocarbon Receptor-interacting Protein-like 1 Is an Obligate Chaperone of Phosphodiesterase 6 and Is Assisted by the γ-Subunit of Its Client. J Biol Chem 2016; 291:16282-91. [PMID: 27268253 DOI: 10.1074/jbc.m116.737593] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 12/26/2022] Open
Abstract
Phosphodiesterase 6 (PDE6) is the effector enzyme in the phototransduction cascade and is critical for the health of both rod and cone photoreceptors. Its dysfunction, caused by mutations in either the enzyme itself or AIPL1 (aryl hydrocarbon receptor-interacting protein-like 1), leads to retinal diseases culminating in blindness. Progress in research on PDE6 and AIPL1 has been severely hampered by failure to express functional PDE6 in a heterologous expression system. Here, we demonstrated that AIPL1 is an obligate chaperone of PDE6 and that it enables low yield functional folding of cone PDE6C in cultured cells. We further show that the AIPL1-mediated production of folded PDE6C is markedly elevated in the presence of the inhibitory Pγ-subunit of PDE6. As illustrated in this study, a simple and sensitive system in which AIPL1 and Pγ are co-expressed with PDE6 represents an effective tool for probing structure-function relationships of AIPL1 and reliably establishing the pathogenicity of its variants.
Collapse
Affiliation(s)
| | - Kimberly Boyd
- From the Departments of Molecular Physiology and Biophysics and
| | - Ravi P Yadav
- From the Departments of Molecular Physiology and Biophysics and
| | - Nikolai O Artemyev
- From the Departments of Molecular Physiology and Biophysics and Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| |
Collapse
|
30
|
A Naturally-Derived Compound Schisandrin B Enhanced Light Sensation in the pde6c Zebrafish Model of Retinal Degeneration. PLoS One 2016; 11:e0149663. [PMID: 26930483 PMCID: PMC4773124 DOI: 10.1371/journal.pone.0149663] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Accepted: 02/03/2016] [Indexed: 11/19/2022] Open
Abstract
Retinal degeneration is often progressive. This feature has provided a therapeutic window for intervention that may extend functional vision in patients. Even though this approach is feasible, few promising drug candidates are available. The scarcity of new drugs has motivated research to discover novel compounds through different sources. One such example is Schisandrin B (SchB), an active component isolated from the five-flavor fruit (Fructus Schisandrae) that is postulated in traditional Chinese medicines to exert prophylactic visual benefit. This SchB benefit was investigated in this study in pde6cw59, a zebrafish retinal-degeneration model. In this model, the pde6c gene (phosphodiesterase 6C, cGMP-specific, cone, alpha prime) carried a mutation which caused cone degeneration. This altered the local environment and caused the bystander rods to degenerate too. To test SchB on the pde6cw59 mutants, a treatment concentration was first determined that would not cause morphological defects, and would initiate known physiological response. Then, the mutants were treated with the optimized SchB concentration before the appearance of retinal degeneration at 3 days postfertilization (dpf). The light sensation of animals was evaluated at 6 dpf by the visual motor response (VMR), a visual startle that could be initiated by drastic light onset and offset. The results show that the VMR of pde6cw59 mutants towards light onset was enhanced by the SchB treatment, and that the initial phase of the enhancement was primarily mediated through the mutants’ eyes. Further immunostaining analysis indicates that the treatment specifically reduced the size of the abnormally large rods. These observations implicate an interesting hypothesis: that the morphologically-improved rods drive the observed VMR enhancement. Together, these investigations have identified a possible visual benefit of SchB on retinal degeneration, a benefit that can potentially be further developed to extend functional vision in patients.
Collapse
|
31
|
Aboshiha J, Dubis AM, Carroll J, Hardcastle AJ, Michaelides M. The cone dysfunction syndromes. Br J Ophthalmol 2016; 100:115-21. [PMID: 25770143 PMCID: PMC4717370 DOI: 10.1136/bjophthalmol-2014-306505] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 02/09/2015] [Indexed: 11/05/2022]
Abstract
The cone dysfunction syndromes are a heterogeneous group of inherited, predominantly stationary retinal disorders characterised by reduced central vision and varying degrees of colour vision abnormalities, nystagmus and photophobia. This review details the following conditions: complete and incomplete achromatopsia, blue-cone monochromatism, oligocone trichromacy, bradyopsia and Bornholm eye disease. We describe the clinical, psychophysical, electrophysiological and imaging findings that are characteristic to each condition in order to aid their accurate diagnosis, as well as highlight some classically held notions about these diseases that have come to be challenged over the recent years. The latest data regarding the genetic aetiology and pathological changes observed in the cone dysfunction syndromes are discussed, and, where relevant, translational avenues of research, including completed and anticipated interventional clinical trials, for some of the diseases described herein will be presented. Finally, we briefly review the current management of these disorders.
Collapse
Affiliation(s)
- Jonathan Aboshiha
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| | - Adam M Dubis
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| | - Joseph Carroll
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Alison J Hardcastle
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| |
Collapse
|
32
|
Simunovic MP. Acquired color vision deficiency. Surv Ophthalmol 2015; 61:132-55. [PMID: 26656928 DOI: 10.1016/j.survophthal.2015.11.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 11/06/2015] [Accepted: 11/11/2015] [Indexed: 02/02/2023]
Abstract
Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.
Collapse
Affiliation(s)
- Matthew P Simunovic
- Nuffield Laboratory of Ophthalmology, University of Oxford & Oxford Eye Hospital, University of Oxford NHS Trust, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, UK.
| |
Collapse
|
33
|
Chen XT, Huang H, Chen YH, Dong LJ, Li XR, Zhang XM. Achromatopsia caused by novel missense mutations in the CNGA3 gene. Int J Ophthalmol 2015; 8:910-5. [PMID: 26558200 DOI: 10.3980/j.issn.2222-3959.2015.05.10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/14/2015] [Indexed: 11/02/2022] Open
Abstract
AIM To identify the genetic defects in a Chinese family with achromatopsia. METHODS A 2.5-year-old boy, who displayed nystagmus, photophobia, and hyperopia since early infancy, was clinically evaluated. To further confirm and localize the causative mutations in this family, targeted region capture and next-generation sequencing of candidate genes, such as CNGA3, CNGB3, GNAT2, PDE6C, and PDE6H were performed using a custom-made capture array. RESULTS Slit-lamp examination showed no specific findings in the anterior segments. The optic discs and maculae were normal on fundoscopy. The unaffected family members reported no ocular complaints. Clinical signs and symptoms were consistent with a clinical impression of autosomal recessive achromatopsia. The results of sequence analysis revealed two novel missense mutations in CNGA3, c.633T>A (p.D211E) and c.1006G>T (p.V336F), with an autosomal recessive mode of inheritance. CONCLUSION Genetic analysis of a Chinese family confirmed the clinical diagnosis of achromatopsia. Two novel mutations were identified in CNGA3, which extended the mutation spectrum of this disorder.
Collapse
Affiliation(s)
- Xi-Teng Chen
- Tianjin Medical University Eye Hospital, Eye Institute & School of Optometry and Ophthalmology, Tianjin 300384, China
| | - Hui Huang
- BGI Health Service Co., Ltd. Airport Industrial Zone, Tianjin 300308, China
| | - Yan-Hua Chen
- BGI Health Service Co., Ltd. Airport Industrial Zone, Tianjin 300308, China
| | - Li-Jie Dong
- Tianjin Medical University Eye Hospital, Eye Institute & School of Optometry and Ophthalmology, Tianjin 300384, China
| | - Xiao-Rong Li
- Tianjin Medical University Eye Hospital, Eye Institute & School of Optometry and Ophthalmology, Tianjin 300384, China
| | - Xiao-Min Zhang
- Tianjin Medical University Eye Hospital, Eye Institute & School of Optometry and Ophthalmology, Tianjin 300384, China
| |
Collapse
|
34
|
Zobor D, Zobor G, Kohl S. Achromatopsia: on the doorstep of a possible therapy. Ophthalmic Res 2015; 54:103-8. [PMID: 26304472 DOI: 10.1159/000435957] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 06/15/2015] [Indexed: 11/19/2022]
Abstract
Achromatopsia (ACHM) is a rare autosomal recessive inherited retinal disorder with an incidence of approximately 1 in 30,000. It presents at birth or early infancy and is typically characterized by reduced visual acuity, nystagmus, photophobia, and very poor or absent color vision. The symptoms arise from isolated cone dysfunction, which can be caused by mutations in the crucial components of the cone phototransduction cascade. Although ACHM is considered a functionally nonprogressive disease affecting only the cone system, recent studies have described progressive age-dependent changes in retinal architecture. Currently, no specific therapy is available for ACHM; however, gene replacement therapy performed on animal models for three ACHM genes has shown promising results. Accurate genetic and clinical diagnosis of patients may therefore enhance and enable therapeutic intervention in the near future. This short review summarizes the genetic background, pathophysiology, clinical findings, diagnostics, and therapeutic perspectives in ACHM.
Collapse
Affiliation(s)
- Ditta Zobor
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | | | | |
Collapse
|
35
|
Sothilingam V, Garcia Garrido M, Jiao K, Buena-Atienza E, Sahaboglu A, Trifunović D, Balendran S, Koepfli T, Mühlfriedel R, Schön C, Biel M, Heckmann A, Beck SC, Michalakis S, Wissinger B, Seeliger MW, Paquet-Durand F. Retinitis pigmentosa: impact of different Pde6a point mutations on the disease phenotype. Hum Mol Genet 2015; 24:5486-99. [PMID: 26188004 DOI: 10.1093/hmg/ddv275] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/09/2015] [Indexed: 11/13/2022] Open
Abstract
Mutations in the PDE6A gene can cause rod photoreceptors degeneration and the blinding disease retinitis pigmentosa (RP). While a number of pathogenic PDE6A mutations have been described, little is known about their impact on compound heterozygous situations and potential interactions of different disease-causing alleles. Here, we used a novel mouse model for the Pde6a R562W mutation in combination with an existing line carrying the V685M mutation to generate compound heterozygous Pde6a V685M/R562W animals, exactly homologous to a case of human RP. We compared the progression of photoreceptor degeneration in these compound heterozygous mice with the homozygous V685M and R562W mutants, and additionally with the D670G line that is known for a relatively mild phenotype. We investigated PDE6A expression, cyclic guanosine mono-phosphate accumulation, calpain and caspase activity, in vivo retinal function and morphology, as well as photoreceptor cell death and survival. This analysis confirms the severity of different Pde6a mutations and indicates that compound heterozygous mutants behave like intermediates of the respective homozygous situations. Specifically, the severity of the four different Pde6a situations may be categorized by the pace of photoreceptor degeneration: V685M (fastest) > V685M/R562W > R562W > D670G (slowest). While calpain activity was strongly increased in all four mutants, caspase activity was not. This points to the execution of non-apoptotic cell death and may lead to the identification of new targets for therapeutic interventions. For individual RP patients, our study may help to predict time-courses for Pde6a-related retinal degeneration and thereby facilitate the definition of a window-of-opportunity for clinical interventions.
Collapse
Affiliation(s)
- Vithiyanjali Sothilingam
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Schleichstr.4/3, Tuebingen 72076, Germany
| | - Marina Garcia Garrido
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Schleichstr.4/3, Tuebingen 72076, Germany
| | - Kangwei Jiao
- Cell Death Mechanisms Group, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Roentgenweg 11, Tuebingen 72076, Germany, Second People's Hospital of Yunnan Province and Fourth Affiliated Hospital of Kunming Medical University, 176 Qingnian Road, Wuhua, Kunming, Yunnan 650021, China
| | - Elena Buena-Atienza
- Molecular Genetics Laboratory, Centre for Ophthalmology, University Clinics Tuebingen, Roentgenweg 11, Tuebingen 72076, Germany
| | - Ayse Sahaboglu
- Cell Death Mechanisms Group, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Roentgenweg 11, Tuebingen 72076, Germany
| | - Dragana Trifunović
- Cell Death Mechanisms Group, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Roentgenweg 11, Tuebingen 72076, Germany
| | - Sukirthini Balendran
- Molecular Genetics Laboratory, Centre for Ophthalmology, University Clinics Tuebingen, Roentgenweg 11, Tuebingen 72076, Germany
| | - Tanja Koepfli
- Molecular Genetics Laboratory, Centre for Ophthalmology, University Clinics Tuebingen, Roentgenweg 11, Tuebingen 72076, Germany
| | - Regine Mühlfriedel
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Schleichstr.4/3, Tuebingen 72076, Germany
| | - Christian Schön
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich 81377, Germany and
| | - Martin Biel
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich 81377, Germany and
| | | | - Susanne C Beck
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Schleichstr.4/3, Tuebingen 72076, Germany
| | - Stylianos Michalakis
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich 81377, Germany and
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Centre for Ophthalmology, University Clinics Tuebingen, Roentgenweg 11, Tuebingen 72076, Germany
| | - Mathias W Seeliger
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Schleichstr.4/3, Tuebingen 72076, Germany
| | - François Paquet-Durand
- Cell Death Mechanisms Group, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Roentgenweg 11, Tuebingen 72076, Germany,
| |
Collapse
|
36
|
Hofmann L, Palczewski K. Advances in understanding the molecular basis of the first steps in color vision. Prog Retin Eye Res 2015; 49:46-66. [PMID: 26187035 DOI: 10.1016/j.preteyeres.2015.07.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 07/07/2015] [Accepted: 07/09/2015] [Indexed: 01/05/2023]
Abstract
Serving as one of our primary environmental inputs, vision is the most sophisticated sensory system in humans. Here, we present recent findings derived from energetics, genetics and physiology that provide a more advanced understanding of color perception in mammals. Energetics of cis-trans isomerization of 11-cis-retinal accounts for color perception in the narrow region of the electromagnetic spectrum and how human eyes can absorb light in the near infrared (IR) range. Structural homology models of visual pigments reveal complex interactions of the protein moieties with the light sensitive chromophore 11-cis-retinal and that certain color blinding mutations impair secondary structural elements of these G protein-coupled receptors (GPCRs). Finally, we identify unsolved critical aspects of color tuning that require future investigation.
Collapse
Affiliation(s)
- Lukas Hofmann
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
| | - Krzysztof Palczewski
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
| |
Collapse
|
37
|
Brennenstuhl C, Tanimoto N, Burkard M, Wagner R, Bolz S, Trifunovic D, Kabagema-Bilan C, Paquet-Durand F, Beck SC, Huber G, Seeliger MW, Ruth P, Wissinger B, Lukowski R. Targeted ablation of the Pde6h gene in mice reveals cross-species differences in cone and rod phototransduction protein isoform inventory. J Biol Chem 2015; 290:10242-55. [PMID: 25739440 DOI: 10.1074/jbc.m114.611921] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Indexed: 11/06/2022] Open
Abstract
Phosphodiesterase-6 (PDE6) is a multisubunit enzyme that plays a key role in the visual transduction cascade in rod and cone photoreceptors. Each type of photoreceptor utilizes discrete catalytic and inhibitory PDE6 subunits to fulfill its physiological tasks, i.e. the degradation of cyclic guanosine-3',5'-monophosphate at specifically tuned rates and kinetics. Recently, the human PDE6H gene was identified as a novel locus for autosomal recessive (incomplete) color blindness. However, the three different classes of cones were not affected to the same extent. Short wave cone function was more preserved than middle and long wave cone function indicating that some basic regulation of the PDE6 multisubunit enzyme was maintained albeit by a unknown mechanism. To study normal and disease-related functions of cone Pde6h in vivo, we generated Pde6h knock-out (Pde6h(-/-)) mice. Expression of PDE6H in murine eyes was restricted to both outer segments and synaptic terminals of short and long/middle cone photoreceptors, whereas Pde6h(-/-) retinae remained PDE6H-negative. Combined in vivo assessment of retinal morphology with histomorphological analyses revealed a normal overall integrity of the retinal organization and an unaltered distribution of the different cone photoreceptor subtypes upon Pde6h ablation. In contrast to human patients, our electroretinographic examinations of Pde6h(-/-) mice suggest no defects in cone/rod-driven retinal signaling and therefore preserved visual functions. To this end, we were able to demonstrate the presence of rod PDE6G in cones indicating functional substitution of PDE6. The disparities between human and murine phenotypes caused by mutant Pde6h/PDE6H suggest species-to-species differences in the vulnerability of biochemical and neurosensory pathways of the visual signal transduction system.
Collapse
Affiliation(s)
- Christina Brennenstuhl
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | | | - Markus Burkard
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | - Rebecca Wagner
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | | | | | - Clement Kabagema-Bilan
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | | | | | | | | | - Peter Ruth
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | - Bernd Wissinger
- the Molecular Genetics Laboratory, Centre for Ophthalmology, University of Tuebingen, 72076 Tuebingen, Germany
| | - Robert Lukowski
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy,
| |
Collapse
|
38
|
Katagiri S, Hayashi T, Yoshitake K, Sergeev Y, Akahori M, Furuno M, Nishino J, Ikeo K, Tsunoda K, Tsuneoka H, Iwata T. Congenital Achromatopsia and Macular Atrophy Caused by a Novel Recessive PDE6C Mutation (p.E591K). Ophthalmic Genet 2015; 36:137-44. [PMID: 25605338 DOI: 10.3109/13816810.2014.991932] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE We have previously reported clinical features of two siblings, a sister with complete achromatopsia (ACHM) and a brother with incomplete ACHM, in a consanguineous Japanese family. With the current study, we intended to identify a disease-causing mutation in the siblings and to investigate why the phenotypes of the siblings differed. METHODS We performed a comprehensive ophthalmic examination for each sibling and parent. Whole-exome and Sanger sequencing were performed on genomic DNA. Molecular modeling was analyzed in an in silico study. RESULTS The ophthalmic examination revealed severe macular atrophy in the older female sibling at 30 years of age and mild macular atrophy in the brother at 26 years of age. The genetic analysis identified a novel homozygous PDE6C mutation (p.E591K) as the disease-causing allele in the siblings. Each parent was heterozygous for the mutation. Molecular modeling showed that the mutation could cause a conformational change in the PDE6C protein and result in reduced phosphodiesterase activity. We also identified an OPN1SW mutation (p.G79R), which is associated with congenital tritan deficiencies, in the sister and the father but not in the brother. CONCLUSIONS A novel homozygous PDE6C mutation was identified as the cause of ACHM. In addition, we identified an OPN1SW mutation in the sibling with complete ACHM, which might explain the difference in phenotype (complete versus incomplete ACHM) between the siblings.
Collapse
Affiliation(s)
- Satoshi Katagiri
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center , Tokyo , Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Cheguru P, Majumder A, Artemyev NO. Distinct patterns of compartmentalization and proteolytic stability of PDE6C mutants linked to achromatopsia. Mol Cell Neurosci 2014; 64:1-8. [PMID: 25461672 DOI: 10.1016/j.mcn.2014.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 10/08/2014] [Accepted: 10/20/2014] [Indexed: 11/19/2022] Open
Abstract
Phosphodiesterase-6 (PDE6) is an essential effector enzyme in vertebrate photoreceptor cells. Mutations in rod and cone PDE6 cause recessive retinitis pigmentosa and achromatopsia, respectively. The mechanisms of missense PDE6 mutations underlying severe visual disorders are poorly understood. To probe these mechanisms, we expressed seven known missense mutants of cone PDE6C in rods of transgenic Xenopus laevis and examined their stability and compartmentalization. PDE6C proteins with mutations in the catalytic domain, H602L and E790K, displayed modestly reduced proteolytic stability, but they were properly targeted to the outer segment of photoreceptor cells. Mutations in the regulatory GAF domains, R104W, Y323N, and P391L led to a proteolytic degradation of the proteins involving a cleavage in the GAFb domain. Lastly, the R29W and M455V mutations residing outside the conserved PDE6 domains produced a pattern of subcellular compartmentalization different from that of PDE6C. Thus, our results suggest a spectrum of mechanisms of missense PDE6C mutations in achromatopsia including catalytic defects, protein mislocalization, or a specific sequence of proteolytic degradation.
Collapse
Affiliation(s)
- Pallavi Cheguru
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, United States
| | - Anurima Majumder
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, United States; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA 52242, United States.
| |
Collapse
|
40
|
Limitations of the ‘ambush hypothesis’ at the single-gene scale: what codon biases are to blame? Mol Genet Genomics 2014; 290:493-504. [DOI: 10.1007/s00438-014-0937-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 10/01/2014] [Indexed: 10/24/2022]
|
41
|
Díez-Fernández C, Hu L, Cervera J, Häberle J, Rubio V. Understanding carbamoyl phosphate synthetase (CPS1) deficiency by using the recombinantly purified human enzyme: effects of CPS1 mutations that concentrate in a central domain of unknown function. Mol Genet Metab 2014; 112:123-32. [PMID: 24813853 DOI: 10.1016/j.ymgme.2014.04.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/11/2014] [Accepted: 04/11/2014] [Indexed: 01/02/2023]
Abstract
Carbamoyl phosphate synthetase 1 deficiency (CPS1D) is an inborn error of the urea cycle that is due to mutations in the CPS1 gene. In the first large repertory of mutations found in CPS1D, a small CPS1 domain of unknown function (called the UFSD) was found to host missense changes with high frequency, despite the fact that this domain does not host substrate-binding or catalytic machinery. We investigate here by in vitro expression studies using baculovirus/insect cells the reasons for the prominence of the UFSD in CPS1D, as well as the disease-causing roles and pathogenic mechanisms of the mutations affecting this domain. All but three of the 18 missense changes found thus far mapping in this domain in CPS1D patients drastically decreased the yield of pure CPS1, mainly because of decreased enzyme solubility, strongly suggesting misfolding as a major determinant of the mutations negative effects. In addition, the majority of the mutations also decreased from modestly to very drastically the specific activity of the fraction of the enzyme that remained soluble and that could be purified, apparently because they decreased V(max). Substantial although not dramatic increases in K(m) values for the substrates or for N-acetyl-L-glutamate were observed for only five mutations. Similarly, important thermal stability decreases were observed for three mutations. The results indicate a disease-causing role for all the mutations, due in most cases to the combined effects of the low enzyme level and the decreased activity. Our data strongly support the value of the present expression system for ascertaining the disease-causing potential of CPS1 mutations, provided that the CPS1 yield is monitored. The observed effects of the mutations have been rationalized on the basis of an existing structural model of CPS1. This model shows that the UFSD, which is in the middle of the 1462-residue multidomain CPS1 protein, plays a key integrating role for creating the CPS1 multidomain architecture leading us to propose here a denomination of "Integrating Domain" for this CPS1 region. The majority of these 18 mutations distort the interaction of this domain with other CPS1 domains, in many cases by causing improper folding of structural elements of the Integrating Domain that play key roles in these interactions.
Collapse
Affiliation(s)
| | - Liyan Hu
- University Children's Hospital, Zurich and Children's Research Center, Zurich, Switzerland
| | - Javier Cervera
- Instituto de Biomedicina de Valencia of the CSIC, Valencia, Spain; Group 739 of the Centro de Investigación Biomédica en Red sobre Enfermedades Raras (CIBERER) del Instituto de Salud Carlos III, Spain
| | - Johannes Häberle
- University Children's Hospital, Zurich and Children's Research Center, Zurich, Switzerland.
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia of the CSIC, Valencia, Spain; Group 739 of the Centro de Investigación Biomédica en Red sobre Enfermedades Raras (CIBERER) del Instituto de Salud Carlos III, Spain.
| |
Collapse
|
42
|
Roosing S, Thiadens AAHJ, Hoyng CB, Klaver CCW, den Hollander AI, Cremers FPM. Causes and consequences of inherited cone disorders. Prog Retin Eye Res 2014; 42:1-26. [PMID: 24857951 DOI: 10.1016/j.preteyeres.2014.05.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 04/29/2014] [Accepted: 05/06/2014] [Indexed: 11/18/2022]
Abstract
Hereditary cone disorders (CDs) are characterized by defects of the cone photoreceptors or retinal pigment epithelium underlying the macula, and include achromatopsia (ACHM), cone dystrophy (COD), cone-rod dystrophy (CRD), color vision impairment, Stargardt disease (STGD) and other maculopathies. Forty-two genes have been implicated in non-syndromic inherited CDs. Mutations in the 5 genes implicated in ACHM explain ∼93% of the cases. On the contrary, only 21% of CRDs (17 genes) and 25% of CODs (8 genes) have been elucidated. The fact that the large majority of COD and CRD-associated genes are yet to be discovered hints towards the existence of unknown cone-specific or cone-sensitive processes. The ACHM-associated genes encode proteins that fulfill crucial roles in the cone phototransduction cascade, which is the most frequently compromised (10 genes) process in CDs. Another 7 CD-associated proteins are required for transport processes towards or through the connecting cilium. The remaining CD-associated proteins are involved in cell membrane morphogenesis and maintenance, synaptic transduction, and the retinoid cycle. Further novel genes are likely to be identified in the near future by combining large-scale DNA sequencing and transcriptomics technologies. For 31 of 42 CD-associated genes, mammalian models are available, 14 of which have successfully been used for gene augmentation studies. However, gene augmentation for CDs should ideally be developed in large mammalian models with cone-rich areas, which are currently available for only 11 CD genes. Future research will aim to elucidate the remaining causative genes, identify the molecular mechanisms of CD, and develop novel therapies aimed at preventing vision loss in individuals with CD in the future.
Collapse
Affiliation(s)
- Susanne Roosing
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | | | - Carel B Hoyng
- Department of Ophthalmology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology Erasmus Medical Centre, 3000 CA, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Centre, 3000 CA, Rotterdam, The Netherlands
| | - Anneke I den Hollander
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Department of Ophthalmology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| |
Collapse
|
43
|
Cheguru P, Zhang Z, Artemyev NO. The GAFa domain of phosphodiesterase-6 contains a rod outer segment localization signal. J Neurochem 2013; 129:256-63. [PMID: 24147783 DOI: 10.1111/jnc.12501] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 10/17/2013] [Accepted: 10/18/2013] [Indexed: 01/21/2023]
Abstract
Photoreceptor phosphodiesterase-6 (PDE6) is a peripheral membrane protein synthesized in the inner segment of photoreceptor cells. Newly synthesized PDE6 is transported to the outer segment (OS) where it serves as a key effector enzyme in the phototransduction cascade. Proper localization of PDE6 in photoreceptors is critically important to the function and survival of photoreceptor cells. The mechanism of PDE6 transport to the OS remains largely unknown. In this study, we investigated potential OS targeting signals of PDE6 by constructing cGMP-binding, cGMP-specific phosphodiesterase-5/PDE6 chimeric proteins and analyzing their localization in rods of transgenic Xenopus laevis. We found that efficient OS localization of chimeric isoprenylated PDE enzymes required the presence of a targeting motif within the PDE6 GAFa domain. Furthermore, the GAFa-dependent localization signal was sufficient to target GAFa fusion protein to the OS. Our results support the idea that effective trafficking of the peripheral membrane proteins to the OS of photoreceptor cells requires a sorting/targeting motif in addition to a membrane-binding signal.
Collapse
Affiliation(s)
- Pallavi Cheguru
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, USA
| | | | | |
Collapse
|
44
|
Martínez-Fernández de la Cámara C, Sequedo MD, Gómez-Pinedo U, Jaijo T, Aller E, García-Tárraga P, García-Verdugo JM, Millán JM, Rodrigo R. Phosphodiesterase inhibition induces retinal degeneration, oxidative stress and inflammation in cone-enriched cultures of porcine retina. Exp Eye Res 2013; 111:122-33. [PMID: 23578797 DOI: 10.1016/j.exer.2013.03.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 03/15/2013] [Accepted: 03/19/2013] [Indexed: 10/27/2022]
Abstract
Inherited retinal degenerations affecting both rod and cone photoreceptors constitute one of the causes of incurable blindness in the developed world. Cyclic guanosine monophosphate (cGMP) is crucial in the phototransduction and, mutations in genes related to its metabolism are responsible for different retinal dystrophies. cGMP-degrading phosphodiesterase 6 (PDE6) mutations cause around 4-5% of the retinitis pigmentosa, a rare form of retinal degeneration. The aim of this study was to evaluate whether pharmacological PDE6 inhibition induced retinal degeneration in cone-enriched cultures of porcine retina similar to that found in murine models. PDE6 inhibition was induced in cone-enriched retinal explants from pigs by Zaprinast. PDE6 inhibition induced cGMP accumulation and triggered retinal degeneration, as determined by TUNEL assay. Western blot analysis and immunostaining indicated that degeneration was accompanied by caspase-3, calpain-2 activation and poly (ADP-ribose) accumulation. Oxidative stress markers, total antioxidant capacity, thiobarbituric acid reactive substances (TBARS) and nitric oxide measurements revealed the presence of oxidative damage. Elevated TNF-alpha and IL-6, as determined by enzyme immunoassay, were also found in cone-enriched retinal explants treated with Zaprinast. Our study suggests that this ex vivo model of retinal degeneration in porcine retina could be an alternative model for therapeutic research into the mechanisms of photoreceptor death in cone-related diseases, thus replacing or reducing animal experiments.
Collapse
|
45
|
Kohl S, Coppieters F, Meire F, Schaich S, Roosing S, Brennenstuhl C, Bolz S, van Genderen M, Riemslag F, Lukowski R, den Hollander A, Cremers F, De Baere E, Hoyng C, Wissinger B, Wissinger B. A nonsense mutation in PDE6H causes autosomal-recessive incomplete achromatopsia. Am J Hum Genet 2012; 91:527-32. [PMID: 22901948 DOI: 10.1016/j.ajhg.2012.07.006] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 03/22/2012] [Accepted: 07/09/2012] [Indexed: 10/28/2022] Open
Abstract
Achromatopsia (ACHM) is an autosomal-recessive retinal dystrophy characterized by color blindness, photophobia, nystagmus, and severely reduced visual acuity. Its prevalence has been estimated to about 1 in 30,000 individuals. Four genes, GNAT2, PDE6C, CNGA3, and CNGB3, have been implicated in ACHM, and all encode functional components of the phototransduction cascade in cone photoreceptors. Applying a functional-candidate-gene approach that focused on screening additional genes involved in this process in a cohort of 611 index cases with ACHM or other cone photoreceptor disorders, we detected a homozygous single base change (c.35C>G) resulting in a nonsense mutation (p.Ser12(∗)) in PDE6H, encoding the inhibitory γ subunit of the cone photoreceptor cyclic guanosine monophosphate phosphodiesterase. The c.35C>G mutation was present in three individuals from two independent families with a clinical diagnosis of incomplete ACHM and preserved short-wavelength-sensitive cone function. Moreover, we show through immunohistochemical colocalization studies in mouse retina that Pde6h is evenly present in all retinal cone photoreceptors, a fact that had been under debate in the past. These findings add PDE6H to the set of genes involved in autosomal-recessive cone disorders and demonstrate the importance of the inhibitory γ subunit in cone phototransduction.
Collapse
|
46
|
Abstract
G protein signaling depends on the ability of the individual subunits of the G protein heterotrimer to assemble into functional complexes. Formation of the G protein βγ (Gβγ) dimer is particularly challenging because it is an obligate dimer in which the individual subunits are unstable on their own. Recent studies have revealed an intricate chaperone system that brings the Gβ and Gγ subunits together. This system includes the cytosolic chaperonin containing TCP-1 (CCT) and its co-chaperone phosducin-like protein 1 (PhLP1). CCT assists Gβ in achieving its β-propeller structure, while PhLP1 releases Gβ from CCT and facilitates its interaction with Gγ. Once Gβγ is formed, PhLP1 remains bound until it is displaced by the Gα subunit and the G protein heterotrimer is brought together. Another obligate dimer is the complex between the G protein β(5) subunit and a regulator of G protein signaling protein (Gβ(5)-RGS). Gβ(5)-RGS also requires CCT for Gβ(5) folding, but PhLP1 plays a different role. It stabilizes the interaction between Gβ(5) and CCT, perhaps to increase folding efficiency. After Gβ(5) folding PhLP1 must subsequently release, allowing the RGS protein to bind and form the Gβ(5)-RGS dimer directly on CCT. Gβ(5)-RGS is then freed from CCT to interact with its membrane anchoring protein and form a stable complex that turns off the G protein signal by catalyzing GTP hydrolysis on Gα.
Collapse
Affiliation(s)
- Barry M Willardson
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, 84602, USA,
| | | |
Collapse
|
47
|
Genead MA, Fishman GA, Rha J, Dubis AM, Bonci DMO, Dubra A, Stone EM, Neitz M, Carroll J. Photoreceptor structure and function in patients with congenital achromatopsia. Invest Ophthalmol Vis Sci 2011; 52:7298-308. [PMID: 21778272 DOI: 10.1167/iovs.11-7762] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To assess photoreceptor structure and function in patients with congenital achromatopsia. METHODS Twelve patients were enrolled. All patients underwent a complete ocular examination, spectral-domain optical coherence tomography (SD-OCT), full-field electroretinographic (ERG), and color vision testing. Macular microperimetry (MP; in four patients) and adaptive optics (AO) imaging (in nine patients) were also performed. Blood was drawn for screening of disease-causing genetic mutations. RESULTS Mean (± SD) age was 30.8 (± 16.6) years. Mean best-corrected visual acuity was 0.85 (± 0.14) logarithm of the minimal angle of resolution (logMAR) units. Seven patients (58.3%) showed either an absent foveal reflex or nonspecific retinal pigment epithelium mottling to mild hypopigmentary changes on fundus examination. Two patients showed an atrophic-appearing macular lesion. On anomaloscopy, only 5 patients matched over the entire range from 0 to 73. SD-OCT examination showed a disruption or loss of the macular inner/outer segments (IS/OS) junction of the photoreceptors in 10 patients (83.3%). Seven of these patients showed an optically empty space at the level of the photoreceptors in the fovea. AO images of the photoreceptor mosaic were highly variable but significantly disrupted from normal. On ERG testing, 10 patients (83.3%) showed evidence of residual cone responses to a single-flash stimulus response. The macular MP testing showed that the overall mean retinal sensitivity was significantly lower than normal (12.0 vs. 16.9 dB, P < 0.0001). CONCLUSIONS The current approach of using high-resolution techniques to assess photoreceptor structure and function in patients with achromatopsia should be useful in guiding selection of patients for future therapeutic trials as well as monitoring therapeutic response in these trials.
Collapse
Affiliation(s)
- Mohamed A Genead
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| | | | | | | | | | | | | | | | | |
Collapse
|