-
Signal Transduction and Targeted Therapy Sep 2023The endoplasmic reticulum (ER) functions as a quality-control organelle for protein homeostasis, or "proteostasis". The protein quality control systems involve... (Review)
Review
The endoplasmic reticulum (ER) functions as a quality-control organelle for protein homeostasis, or "proteostasis". The protein quality control systems involve ER-associated degradation, protein chaperons, and autophagy. ER stress is activated when proteostasis is broken with an accumulation of misfolded and unfolded proteins in the ER. ER stress activates an adaptive unfolded protein response to restore proteostasis by initiating protein kinase R-like ER kinase, activating transcription factor 6, and inositol requiring enzyme 1. ER stress is multifaceted, and acts on aspects at the epigenetic level, including transcription and protein processing. Accumulated data indicates its key role in protein homeostasis and other diverse functions involved in various ocular diseases, such as glaucoma, diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa, achromatopsia, cataracts, ocular tumors, ocular surface diseases, and myopia. This review summarizes the molecular mechanisms underlying the aforementioned ocular diseases from an ER stress perspective. Drugs (chemicals, neurotrophic factors, and nanoparticles), gene therapy, and stem cell therapy are used to treat ocular diseases by alleviating ER stress. We delineate the advancement of therapy targeting ER stress to provide new treatment strategies for ocular diseases.
Topics: Humans; Endoplasmic Reticulum Stress; Unfolded Protein Response; Color Vision Defects; Autophagy; Epigenomics
PubMed: 37709773
DOI: 10.1038/s41392-023-01570-w -
Genetics in Medicine : Official Journal... Dec 2023CNGA3 encoding the main subunit of the cyclic nucleotide-gated ion channel in cone photoreceptors is one of the major disease-associated genes for achromatopsia. Most...
PURPOSE
CNGA3 encoding the main subunit of the cyclic nucleotide-gated ion channel in cone photoreceptors is one of the major disease-associated genes for achromatopsia. Most CNGA3 variants are missense variants with the majority being functionally uncharacterized and therefore hampering genetic diagnosis. In light of potential gene therapy, objective variant pathogenicity assessment is essential.
METHODS
We established a medium-throughput aequorin-based luminescence bioassay allowing mutant CNGA3 channel function assessment via quantification of CNGA3 channel-mediated calcium influx in a cell culture system, thereby enabling American College of Medical Genetics and Genomics/Association for Molecular Pathology-based variant re-classification.
RESULTS
We provide functional read-out obtained for 150 yet uncharacterized CNGA3 missense substitutions of which 55 were previously categorized as variants of uncertain significance (VUS) identifying 25 as functionally normal and 125 as functionally abnormal. These data enabled the American College of Medical Genetics and Genomics/ Association for Molecular Pathology-based variant re-classification of 52/55 VUS as either benign, likely benign, or likely pathogenic reaching a VUS re-classification rate of 94.5%.
CONCLUSION
Our aequorin-based bioassay allows functionally ensured clinical variant interpretation for 150 CNGA3 missense variants enabling and supporting VUS re-classification and assuring molecular diagnosis to patients affected by CNGA3-associated achromatopsia, hereby identifying patients eligible for future gene therapy trials on this disease.
Topics: Humans; Color Vision Defects; Aequorin; Retinal Cone Photoreceptor Cells; Mutation, Missense; Genomics; Cyclic Nucleotide-Gated Cation Channels
PubMed: 37689994
DOI: 10.1016/j.gim.2023.100979 -
PloS One 2023Colour-related search tasks are common in many professional fields. The study investigated whether increasing chromatic saturation can enhance the visual performance of...
BACKGROUND
Colour-related search tasks are common in many professional fields. The study investigated whether increasing chromatic saturation can enhance the visual performance of individuals with colour vision deficiency (CVD) in colour-related search tasks.
METHODS
10 normal trichromats (5M, 5F; Mean (SD) age: 23.1 (3.3) years) and 15 individuals with CVD [8 deutans and 7 protans identified by HRR plates] (14M, 1F; aged 28.6 (8.7) years) participated in this study. Four naturalistic sceneries of everyday tasks/ birds, animals and flowers of 15 different colour combinations (1 pair of colours in each combination. e.g., 'brown/black' or 'red/green') were presented in 'low' saturation, 'original' (unaltered images) and 'high' saturation condition using the Psychopy program on a colour-calibrated monitor. On each trial, the subject was asked to identify a specific-coloured target.
RESULTS
Overall, the visual search performance index (expressed as product of accuracy and a reciprocal of reaction time (%correct*s-1) of the normal trichromats [Mean (SD):77.76% correct*s-1 (16.32)] was significantly higher than CVD [45.71% correct*s-1 (18.95)] in the "original" test images (p = 0.001), but in individuals with CVD, there was no significant difference between 'original' [45.71% correct*s-1 (18.95)] and 'high' saturation condition ([47.43% correct*s-1 (20.07)]; p > 0.05). However, colour-wise, increased saturation showed improvements (≥ 10%) in protans mainly for 'red' combinations with other colours such as white (i.e., 'red/white'), purple, orange, grey, green, brown and black.
CONCLUSION
The study suggests that increasing the saturation of certain colour combinations can potentially aid in the visual search performance of individuals with CVD. This knowledge will help in better counselling and management of the patients.
Topics: Animals; Chemical Phenomena; Color Vision Defects; Flowers; Humans; Male; Female; Young Adult; Adult
PubMed: 37682873
DOI: 10.1371/journal.pone.0290782 -
Documenta Ophthalmologica. Advances in... Dec 2023Biallelic mutations in the CEP290 gene cause early onset retinal dystrophy or syndromic disease such as Senior-Loken or Joubert syndrome. Here, we present an unusual...
PURPOSE
Biallelic mutations in the CEP290 gene cause early onset retinal dystrophy or syndromic disease such as Senior-Loken or Joubert syndrome. Here, we present an unusual non-syndromic case of a juvenile retinal dystrophy caused by biallelic CEP290 mutations imitating initially the phenotype of achromatopsia or slowly progressing cone dystrophy.
METHODS
We present 13 years of follow-up of a female patient who presented first with symptoms and findings typical for achromatopsia. The patient underwent functional and morphologic examinations, including fundus autofluorescence imaging, spectral-domain optical coherence tomography, electroretinography, color vision and visual field testing.
RESULTS
Diagnostic genetic testing via whole genome sequencing and virtual inherited retinal disease gene panel evaluation finally identified two compound heterozygous variants c.4452_4455del;p.(Lys1484Asnfs*4) and c.2414T > C;p.(Leu805Pro) in the CEP290 gene.
CONCLUSIONS
CEP290 mutation causes a wide variety of clinical phenotypes. The presented case shows a phenotype resembling achromatopsia or early onset slowly progressing cone dystrophy.
Topics: Humans; Female; Cone Dystrophy; Color Vision Defects; Electroretinography; Mutation; Phenotype; Retinal Dystrophies; Tomography, Optical Coherence
PubMed: 37642804
DOI: 10.1007/s10633-023-09940-z -
Ophthalmology Dec 2023To describe the largest, most phenotypically and genetically diverse cohort of patients with inherited retinal disease (IRD)-related Coats-like vasculopathy (CLV).
PURPOSE
To describe the largest, most phenotypically and genetically diverse cohort of patients with inherited retinal disease (IRD)-related Coats-like vasculopathy (CLV).
DESIGN
Multicenter retrospective cohort study.
PARTICIPANTS
A total of 67 patients with IRD-related CLV.
METHODS
Review of clinical notes, ophthalmic imaging, and molecular diagnosis from 2 international centers.
MAIN OUTCOME MEASURES
Visual function, retinal imaging, management, and response to treatment were evaluated and correlated.
RESULTS
The prevalence of IRD-related CLV was 0.5%; 54% of patients had isolated retinitis pigmentosa (RP), 21% had early-onset severe retinal dystrophy, and less frequent presentations were syndromic RP, sector RP, cone-rod dystrophy, achromatopsia, PAX6-related dystrophy, and X-linked retinoschisis. The overall age of patients at CLV diagnosis was 30.7 ± 16.9 years (1-83). Twenty-one patients (31%) had unilateral CLV, and the most common retinal features were telangiectasia, exudates, and exudative retinal detachment (ERD) affecting the inferior and temporal retina. Macular edema/schisis was observed in 26% of the eyes, and ERD was observed in 63% of the eyes. Fifty-four patients (81%) had genetic testing, 40 of whom were molecularly solved. Sixty-six eyes (58%) were observed, 17 eyes (15%) were treated with a single modality, and 30 eyes (27%) had a combined approach. Thirty-five eyes (31%) were "good responders," 42 eyes (37%) were "poor responders," 22 eyes (19%) had low vision at baseline and were only observed, and 12 eyes (11%) did not have longitudinal assessment. Twenty-one observed eyes (62%) responded well versus 14 (33%) treated eyes. Final best-corrected visual acuity was significantly worse than baseline (P = 0.002); 40 patients (60%) lost 15 ETDRS letters or more over follow-up in 1 or both eyes, and 21 patients (31%) progressed to more advanced stages of visual impairment.
CONCLUSIONS
Inherited retinal disease-related CLV is rare, sporadic, and mostly bilateral; there is no gender predominance, and it can occur in diverse types of IRD at any point of the disease, with a mean onset in the fourth decade of life. Patients with IRD-related CLV who have decreased initial visual acuity, ERD, CLV changes affecting 2 or more retinal quadrants, and CRB1-retinopathy may be at higher risk of a poor prognosis.
FINANCIAL DISCLOSURE(S)
Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
Topics: Humans; Infant; Child, Preschool; Child; Adolescent; Young Adult; Adult; Middle Aged; Aged; Aged, 80 and over; Prevalence; Retrospective Studies; Retina; Retinal Detachment; Retinal Dystrophies; Retinitis Pigmentosa; Cone-Rod Dystrophies; Vision, Low; Eye Proteins; Membrane Proteins; Nerve Tissue Proteins
PubMed: 37544434
DOI: 10.1016/j.ophtha.2023.07.027 -
Sensors (Basel, Switzerland) Jul 2023Ensuring the quality of color contact lenses is vital, particularly in detecting defects during their production since they are directly worn on the eyes. One...
Ensuring the quality of color contact lenses is vital, particularly in detecting defects during their production since they are directly worn on the eyes. One significant defect is the "center deviation (CD) defect", where the colored area (CA) deviates from the center point. Measuring the extent of deviation of the CA from the center point is necessary to detect these CD defects. In this study, we propose a method that utilizes image processing and analysis techniques for detecting such defects. Our approach involves employing semantic segmentation to simplify the image and reduce noise interference and utilizing the Hough circle transform algorithm to measure the deviation of the center point of the CA in color contact lenses. Experimental results demonstrated that our proposed method achieved a 71.2% reduction in error compared with existing research methods.
PubMed: 37514827
DOI: 10.3390/s23146533 -
Journal of Personalized Medicine Jul 2023(1) Background: Achromatopsia is a rare disease of which the natural course and impact on life are still unknown to this date. We aimed to assess the morphological,...
(1) Background: Achromatopsia is a rare disease of which the natural course and impact on life are still unknown to this date. We aimed to assess the morphological, functional characteristics, and quality of life in a large sample size of patients with achromatopsia. (2) A total of 94 achromats were included in this retrospective cohort study. Sixty-four were patients of the Department of Ophthalmology, Saarland University Medical Centre in Homburg/Saar, Germany, between 2008 and 2021. Thirty further participants with achromatopsia from the national support group were included using an online questionnaire, which is available under 'Supplementary data'. Statistical analysis was performed using SPSS Version 25; (3) The 94 patients (37 males (39.4%) and 57 females (60.6%)) showed a mean age of 24.23 ± 18.53 years. Visual acuity was stable (SD ± 0.22 logMAR at 1.0 logMAR) over a time of observation from 2008 to 2021. Edge filter glasses were the most used optical aids, while enlarged reading glasses were the most used low vision aids. (4) Conclusions: Our findings give an insight into describing the natural process and the quality of life of achromatopsia. The results demonstrate that achromatopsia is a predominantly stationary disease. The individual prescription of edge filters and low-vision aids is essential following a personalised fitting.
PubMed: 37511719
DOI: 10.3390/jpm13071106 -
Advances in Experimental Medicine and... 2023The cone photoreceptor cyclic nucleotide-gated (CNG) channel plays a pivotal role in cone phototransduction. Mutations in genes encoding the channel subunits CNGA3 and...
The cone photoreceptor cyclic nucleotide-gated (CNG) channel plays a pivotal role in cone phototransduction. Mutations in genes encoding the channel subunits CNGA3 and CNGB3 account for about 80% of all cases of achromatopsia and are associated with progressive cone dystrophies. CNG channel deficiency leads to cellular/endoplasmic reticulum (ER) calcium dysregulation and ER stress-associated cone apoptosis. This work investigated the role of the ER calcium channel ryanodine receptor 1 (Ryr1) in ER stress and cone degeneration in CNG channel deficiency. The AAV-mediated CRISPR/SaCas9 genome editing was used to knock down Ryr1 specifically in cones. CNG channel-deficient mice displayed improved cone survival after subretinal injection of AAV2-SaCas9/gRNA-Ryr1, manifested as increased expression levels of cone proteins M-opsin, S-opsin, and cone arrestin. Knockdown of Ryr1 also led to reduced ER stress and increased expression levels of the ER-associated degradation proteins. This work demonstrates a role of Ryr1 in ER stress and cone degeneration in CNG channel deficiency, and supports strategies targeting ER calcium regulation for cone preservation.
Topics: Animals; Mice; Cyclic Nucleotide-Gated Cation Channels; Ryanodine Receptor Calcium Release Channel; Calcium; Proteolysis; Retinal Cone Photoreceptor Cells; Endoplasmic Reticulum; Opsins; Nucleotides, Cyclic
PubMed: 37440056
DOI: 10.1007/978-3-031-27681-1_51 -
Human Molecular Genetics Aug 2023Phosphodiesterase-6 (PDE6) is the key phototransduction effector enzyme residing in the outer segment (OS) of photoreceptors. Cone PDE6 is a tetrameric protein...
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.
Topics: Humans; Mice; Animals; Cyclic Nucleotide Phosphodiesterases, Type 6; Retinal Cone Photoreceptor Cells; Light Signal Transduction; Prenylation
PubMed: 37384398
DOI: 10.1093/hmg/ddad108 -
Genes Jun 2023Achromatopsia (ACHM) is a congenital cone photoreceptor disorder characterized by reduced visual acuity, nystagmus, photophobia, and very poor or absent color vision....
Achromatopsia (ACHM) is a congenital cone photoreceptor disorder characterized by reduced visual acuity, nystagmus, photophobia, and very poor or absent color vision. Pathogenic variants in six genes encoding proteins composing the cone phototransduction cascade (, , , , ) and of the unfolded protein response () have been related to ACHM cases, while and alone are responsible for most cases. Herein, we provide a clinical and molecular overview of 42 Brazilian patients from 38 families affected with ACHM related to biallelic pathogenic variants in the and genes. Patients' genotype and phenotype were retrospectively evaluated. The majority of variants were missense, and the most prevalent variant was c.1148delC (p.Thr383Ilefs*13), resulting in a frameshift and premature stop codon, which is compatible with previous publications in the literature. A novel variant c.1893T>A (p.Tyr631*) in the gene is reported for the first time in this study. A great variability in morphologic findings was observed in our patients, although no consistent correlation with age and disease stage in OCT foveal morphology was found. The better understanding of the genetic variants landscape in the Brazilian population will help in the diagnosis of this disease.
Topics: Humans; Color Vision Defects; Mutation; Brazil; Retrospective Studies; Cyclic Nucleotide-Gated Cation Channels
PubMed: 37372476
DOI: 10.3390/genes14061296