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Zhang X, Yao S, Zhang L, Yang L, Yang M, Guo Q, Li Y, Wang Z, Lei B, Jin X. Mechanisms underlying morphological and functional changes of cilia in fibroblasts derived from patients bearing ARL3 T31A and ARL3 T31A/C118F mutations. FASEB J 2024; 38:e23519. [PMID: 38457249 DOI: 10.1096/fj.202301906r] [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: 09/18/2023] [Revised: 01/31/2024] [Accepted: 02/15/2024] [Indexed: 03/10/2024]
Abstract
ARL3 is essential for cilia development, and mutations in ARL3 are closely associated with ciliopathies. In a previous study, we observed distinct phenotypes of retinal dystrophy in patients with heterozygous ARL3T31A and compound heterozygous ARL3T31A/C118F mutations, indicating that different mutation types may exert diverse effects on their functions. Here, we generated transformed immortal fibroblast cells from patients carrying heterozygous ARL3T31A and compound heterozygous ARL3T31A/C118F mutations, and systematically evaluated their cilia morphology and function, which were further validated in ARPE-19 cells. Results showed that both ARL3T31A and ARL3T31A/C118F mutations led to a decrease in cilium formation. The ARL3T31A/C118F mutations caused significantly elongated cilia and impaired retrograde transport, whereas the ARL3T31A mutation did not induce significant changes in fibroblasts. RNA-sequencing results indicated that compared to ARL3T31A , ARL3T31A/C118F fibroblasts exhibited a higher enrichment of biological processes related to neuron projection development, tissue morphogenesis, and extracellular matrix (ECM) organization, with noticeable alterations in pathways such as ECM-receptor interaction, focal adhesion, and TGF-β signaling. Similar changes were observed in the proteomic results in ARPE-19 cells. Core regulated genes including IQUB, UNC13D, RAB3IP, and GRIP1 were specifically downregulated in the ARL3T31A/C118F group, and expressions of IQUB, NPM2, and SLC38A4 were further validated. Additionally, IQUB showed a rescuing effect on the overlong cilia observed in ARL3T31A/C118F fibroblasts. Our results not only enhance our understanding of ARL3-related diseases but also provide new insights into the analysis of heterozygous and compound heterozygous mutations in genetics.
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Affiliation(s)
- Xiaoli Zhang
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan, China
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience and The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Eye Institute, Henan Academy of Innovations in Medical Science, Zhengzhou, Henan, China
| | - Shun Yao
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan, China
| | - Lujia Zhang
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience and The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Lin Yang
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan, China
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, China
| | - Mingzhu Yang
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan, China
| | - Qingge Guo
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan, China
| | - Yan Li
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan, China
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, China
| | - Zhongfeng Wang
- Institute of Neuroscience and The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Bo Lei
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan, China
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, China
- Eye Institute, Henan Academy of Innovations in Medical Science, Zhengzhou, Henan, China
| | - Xiuxiu Jin
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan, China
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, China
- Eye Institute, Henan Academy of Innovations in Medical Science, Zhengzhou, Henan, China
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Yang S, Li Y, Yang L, Guo Q, You Y, Lei B. Pathogenicity and functional analysis of CFAP410 mutations causing cone-rod dystrophy with macular staphyloma. Front Med (Lausanne) 2023; 10:1216427. [PMID: 37901396 PMCID: PMC10601463 DOI: 10.3389/fmed.2023.1216427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 09/25/2023] [Indexed: 10/31/2023] Open
Abstract
Background Cone-rod dystrophy (CORD) caused by pathogenic variants in CFAP410 is a very rare disease. The mechanisms by which the variants caused the disease remained largely unknown. CFAP410 pathogenic variants were identified in a cone-rod dystrophy with macular staphyloma patient. We explored the pathogenicity and performed functional analysis of two compound heterozygous mutations. Methods A 6-year-old boy complained decreased vision for 1 year, underwent ocular examinations together with systemic X-ray check. Blood sample was taken for targeted next generation sequencing (Tg-NGS). Pathogenicity of identified variants was determined by ACMG guideline. Mutated plasmids were constructed and transferred to HEK293T cells. Cell cycle, protein stability, and protein ubiquitination level was measured. Results The best-corrected visual acuity of proband was 0.20 bilaterally. Fundus showed macular staphyloma and uneven granular pigment disorder in the periphery of the retina. SS-OCT showed thinning and atrophy of the outer retina, residual ellipsoid zone (EZ) in the fovea. Scotopic and photopic ERG responses severe reduced. Two heterozygous missense pathogenic variants, c.319 T > C (p.Tyr107His) and c.347 C > T (p.Pro116Leu) in exon 4 of the CFAP410, were found and were pathogenic by the ACMG guideline. In vitro, pathogenic variants affect cell cycle. Immunofluorescence and western blotting showed that the mutant proteins decreased expression levels protein stability. Meanwhile, co-IP data suggested that ubiquitination level was altered in cells transferred with the mutated plasmids. Conclusion Compound heterozygous pathogenic variants c.319 T > C and c.347 C > T in CFAP410 caused CORD with macular staphyloma. The pathogenic mechanisms may be associated with alternations of protein stability and degradation through the ubiquitin-proteasome pathway.
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Affiliation(s)
- Shaoqing Yang
- Henan University People’s Hospital, Henan Provincial People’s Hospital, Zhengzhou, China
| | - Ya Li
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou, China
| | - Lin Yang
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou, China
| | - Qingge Guo
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou, China
| | - Ya You
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou, China
| | - Bo Lei
- Henan University People’s Hospital, Henan Provincial People’s Hospital, Zhengzhou, China
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou, China
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Zhen T, Li Y, Guo Q, Yao S, You Y, Lei B. Pathogenicity and Function Analysis of Two Novel SLC4A11 Variants in Patients With Congenital Hereditary Endothelial Dystrophy. Transl Vis Sci Technol 2023; 12:1. [PMID: 37787991 PMCID: PMC10561774 DOI: 10.1167/tvst.12.10.1] [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: 04/12/2023] [Accepted: 08/10/2023] [Indexed: 10/04/2023] Open
Abstract
Purpose The purpose of this study was to explore the pathogenicity and function of two novel SLC4A11 variants associated with congenital hereditary endothelial dystrophy (CHED) and to study the function of a SLC4A11 (K263R) mutant in vitro. Methods Ophthalmic examinations were performed on a 28-year-old male proband with CHED. Whole-exome and Sanger sequencing were applied for mutation screening. Bioinformatics and pathogenicity analysis were performed. HEK293T cells were transfected with the plasmids of empty vector, wild-type SLC4A11, and SLC4A11 (K263R) mutant. The transfected cells were treated with SkQ1. Oxygen consumption, cellular reactive oxygen species (ROS) level, mitochondrial membrane potential, and apoptosis rate were measured. Results The proband had poor visual acuity with nystagmus since childhood. Corneal foggy opacity was evident in both eyes. Two novel SLC4A11 variants were detected. Sanger sequencing showed that the proband's father and sister carried c.1464-1G>T variant, and the proband's mother and sister carried c.788A>G (p.Lys263Arg) variant. Based on the American College of Medical Genetics (ACMG) guidelines, SLC4A11 c.1464-1G>T was pathogenic, whereas c.788A>G, p.K263R was a variant of undetermined significance. In vitro, SLC4A11 (K263R) variant increased ROS level and apoptosis rate. Decrease in mitochondrial membrane potential and oxygen consumption rate were remarkable. Furthermore, SkQ1 decreased ROS levels and apoptosis rate but increased mitochondrial membrane potential in the transfected cells. Conclusions Two novel heterozygous pathogenic variants of the SLC4A11 gene were identified in a family with CHED. The missense variant SLC4A11 (K263R) caused mitochondrial dysfunction and increased apoptosis in mutant transfected cells. In addition, SkQ1 presented a protective effect suggesting the anti-oxidant might be a novel therapeutic drug. Translational Relevance This study verified the pathogenicity of 2 novel variants in the SLC4A11 gene in a CHED family and found an anti-oxidant might be a new drug.
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Affiliation(s)
- Tianjiao Zhen
- Henan University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China
| | - Ya Li
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Qingge Guo
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Shun Yao
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Ya You
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Bo Lei
- Henan University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
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Zhang RK, Sun WY, Liu YX, Zhang EY, Fan ZC. RABL2 promotes the outward transition zone passage of signaling proteins in cilia via ARL3. Proc Natl Acad Sci U S A 2023; 120:e2302603120. [PMID: 37579161 PMCID: PMC10450674 DOI: 10.1073/pnas.2302603120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 07/10/2023] [Indexed: 08/16/2023] Open
Abstract
Certain transmembrane and membrane-tethered signaling proteins export from cilia as BBSome cargoes via the outward BBSome transition zone (TZ) diffusion pathway, indispensable for maintaining their ciliary dynamics to enable cells to sense and transduce extracellular stimuli inside the cell. Murine Rab-like 2 (Rabl2) GTPase resembles Chlamydomonas Arf-like 3 (ARL3) GTPase in promoting outward TZ passage of the signaling protein cargo-laden BBSome. During this process, ARL3 binds to and recruits the retrograde IFT train-dissociated BBSome as its effector to diffuse through the TZ for ciliary retrieval, while how RABL2 and ARL3 cross talk in this event remains uncertain. Here, we report that Chlamydomonas RABL2 in a GTP-bound form (RABL2GTP) cycles through cilia via IFT as an IFT-B1 cargo, dissociates from retrograde IFT trains at a ciliary region right above the TZ, and converts to RABL2GDP for activating ARL3GDP as an ARL3 guanine nucleotide exchange factor. This confers ARL3GTP to detach from the ciliary membrane and become available for binding and recruiting the phospholipase D (PLD)-laden BBSome, autonomous of retrograde IFT association, to diffuse through the TZ for ciliary retrieval. Afterward, RABL2GDP exits cilia by being bound to the ARL3GTP/BBSome entity as a BBSome cargo. Our data identify ciliary signaling proteins exported from cilia via the RABL2-ARL3 cascade-mediated outward BBSome TZ diffusion pathway. According to this model, hedgehog signaling defect-induced Bardet-Biedl syndrome caused by RABL2 mutations in humans could be well explained in a mutation-specific manner, providing us with a mechanistic understanding behind the outward BBSome TZ passage required for proper ciliary signaling.
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Affiliation(s)
- Rui-Kai Zhang
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin300457, China
| | - Wei-Yue Sun
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin300457, China
| | - Yan-Xia Liu
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin300457, China
| | | | - Zhen-Chuan Fan
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin300457, China
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5
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Liu YX, Li WJ, Zhang RK, Sun SN, Fan ZC. Unraveling the intricate cargo-BBSome coupling mechanism at the ciliary tip. Proc Natl Acad Sci U S A 2023; 120:e2218819120. [PMID: 36943875 PMCID: PMC10068815 DOI: 10.1073/pnas.2218819120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 02/13/2023] [Indexed: 03/23/2023] Open
Abstract
Certain ciliary transmembrane and membrane-tethered signaling proteins migrate from the ciliary tip to base via retrograde intraflagellar transport (IFT), essential for maintaining their ciliary dynamics to enable cells to sense and transduce extracellular stimuli inside the cell. During this process, the BBSome functions as an adaptor between retrograde IFT trains and these signaling protein cargoes. The Arf-like 13 (ARL13) small GTPase resembles ARL6/BBS3 in facilitating these signaling cargoes to couple with the BBSome at the ciliary tip prior to loading onto retrograde IFT trains for transporting towards the ciliary base, while the molecular basis for how this intricate coupling event happens remains elusive. Here, we report that Chlamydomonas ARL13 only in a GTP-bound form (ARL13GTP) anchors to the membrane for diffusing into cilia. Upon entering cilia, ARL13 undergoes GTPase cycle for shuttling between the ciliary membrane (ARL13GTP) and matrix (ARL13GDP). To achieve this goal, the ciliary membrane-anchored BBS3GTP binds the ciliary matrix-residing ARL13GDP to activate the latter as an ARL13 guanine nucleotide exchange factor. At the ciliary tip, ARL13GTP recruits the ciliary matrix-residing and post-remodeled BBSome as an ARL13 effector to anchor to the ciliary membrane. This makes the BBSome spatiotemporally become available for the ciliary membrane-tethered phospholipase D (PLD) to couple with. Afterward, ARL13GTP hydrolyzes GTP for releasing the PLD-laden BBSome to load onto retrograde IFT trains. According to this model, hedgehog signaling defects associated with ARL13b and BBS3 mutations in humans could be satisfactorily explained, providing us a mechanistic understanding behind BBSome-cargo coupling required for proper ciliary signaling.
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Affiliation(s)
- Yan-Xia Liu
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin300457, China
| | - Wen-Juan Li
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin300457, China
| | - Rui-Kai Zhang
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin300457, China
| | - Sheng-Nan Sun
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin300457, China
| | - Zhen-Chuan Fan
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin300457, China
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Sangermano R, Galdikaité-Braziené E, Bujakowska KM. Non-syndromic Retinal Degeneration Caused by Pathogenic Variants in Joubert Syndrome Genes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:173-182. [PMID: 37440031 DOI: 10.1007/978-3-031-27681-1_26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Inherited retinal degenerations (IRDs) are a group of genetic disorders characterized by progressive dysfunction and loss of photoreceptors. IRDs are classified as non-syndromic or syndromic, depending on whether retinal degeneration manifests alone or in combination with other associated symptoms. Joubert syndrome (JBTS) is a genetically and clinically heterogeneous disorder affecting the central nervous system and other organs and tissues, including the neuroretina. To date, 39 genes have been associated with JBTS, a majority of which encode structural or functional components of the primary cilium, a specialized sensory organelle present in most post-mitotic cells, including photoreceptors. The use of whole exome and IRD panel next-generation sequencing in routine diagnostics of non-syndromic IRD cases led to the discovery of pathogenic variants in JBTS genes that cause photoreceptor loss without other syndromic features. Here, we recapitulate these findings, describing the JBTS gene defects leading to non-syndromic IRDs.
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Affiliation(s)
- Riccardo Sangermano
- Ocular Genomics Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Egle Galdikaité-Braziené
- Ocular Genomics Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Kinga M Bujakowska
- Ocular Genomics Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
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Travis AM, Pearring JN. Human Mutations in Arl3, a Small GTPase Involved in Lipidated Cargo Delivery to the Cilia, Cause Retinal Dystrophy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:283-288. [PMID: 37440046 DOI: 10.1007/978-3-031-27681-1_41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Photoreceptors are highly polarized sensory neurons. Precise localization of signaling molecules within the ciliary outer segment is critical for photoreceptor function and viability. The small GTPase Arl3 plays a particularly important role in photoreceptors as it regulates outer segment enrichment of lipidated proteins essential for the visual response: transducin-α, transducin-γ, PDEα, PDE β, and Grk1. Recently, mutations in Arl3 have been identified in human patients with nonsyndromic autosomal recessive and dominant inherited retinal degenerations as well as syndromic Joubert syndrome including retinal dystrophy.
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Affiliation(s)
- Amanda M Travis
- Department of Ophthalmology and Visual Science, University of Michigan, Ann Arbor, MI, USA
| | - Jillian N Pearring
- Department of Ophthalmology and Visual Science, University of Michigan, Ann Arbor, MI, USA.
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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8
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Travis AM, Manocha S, Willer JR, Wessler TS, Skiba NP, Pearring JN. Disrupting the ciliary gradient of active Arl3 affects rod photoreceptor nuclear migration. eLife 2023; 12:80533. [PMID: 36598133 PMCID: PMC9831603 DOI: 10.7554/elife.80533] [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: 05/24/2022] [Accepted: 01/03/2023] [Indexed: 01/05/2023] Open
Abstract
The small GTPase Arl3 is important for the enrichment of lipidated proteins to primary cilia, including the outer segment of photoreceptors. Human mutations in the small GTPase Arl3 cause both autosomal recessive and dominant inherited retinal dystrophies. We discovered that dominant mutations result in increased active G-protein-Arl3-D67V has constitutive activity and Arl3-Y90C is fast cycling-and their expression in mouse rods resulted in a displaced nuclear phenotype due to an aberrant Arl3-GTP gradient. Using multiple strategies, we go on to show that removing or restoring the Arl3-GTP gradient within the cilium is sufficient to rescue the nuclear migration defect. Together, our results reveal that an Arl3 ciliary gradient is involved in proper positioning of photoreceptor nuclei during retinal development.
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Affiliation(s)
- Amanda M Travis
- Department of Ophthalmology and Visual Science, University of Michigan-Ann ArborAnn ArborUnited States
| | - Samiya Manocha
- Department of Ophthalmology and Visual Science, University of Michigan-Ann ArborAnn ArborUnited States
| | - Jason R Willer
- Department of Ophthalmology and Visual Science, University of Michigan-Ann ArborAnn ArborUnited States
| | - Timothy S Wessler
- Department of Mathematics, University of North Carolina at Chapel HillChapel HillUnited States
| | - Nikolai P Skiba
- Department of Ophthalmology, Duke UniversityDurhamUnited States
| | - Jillian N Pearring
- Department of Ophthalmology and Visual Science, University of Michigan-Ann ArborAnn ArborUnited States,Department of Cell and Developmental Biology, University of Michigan–Ann ArborAnn ArborUnited States
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Xu H, Chen M. Immune response in retinal degenerative diseases - Time to rethink? Prog Neurobiol 2022; 219:102350. [PMID: 36075351 DOI: 10.1016/j.pneurobio.2022.102350] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 08/24/2022] [Accepted: 09/02/2022] [Indexed: 11/30/2022]
Abstract
Retinal degeneration comprises a group of diseases whereby either the retinal neurons or the neurovascular unit degenerates leading to the loss of visual function. Although the initial cause varies in different conditions, inflammation is known to play an important role in disease pathogenesis. Recent advances in molecular and cell biology and systems biology have yielded unexpected findings, including the heterogeneity of immune cells in the degenerative retina, bidirectional neuron-microglia cross talk, and links to the gut microbiome. Here we discuss the immune response in retinal degenerative conditions, taking into account both regional (retinal) and systemic factors. We propose to classify retinal degeneration into dry and wet forms based on whether the blood-retinal barrier (BRB) is breached and fluid is accumulated in retinal parenchyma. The dry form has a relatively intact BRB and is characterised by progressive retinal thinning. Immune response to degenerative insults is dominated by the retinal defence system, which remains to be regulated by neurons. In contrast, the wet form has retinal oedema due to BRB damaged. Inflammation is executed by infiltrating immune cells as well as the retinal defence system. The gut microbiome will have easy access to the retina in wet retinal degeneration and may affect significantly retinal immune response.
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Affiliation(s)
- Heping Xu
- Aier Institute of Optometry and Vision Science, Changsha 410000, China; The Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, BT9 7BL, UK.
| | - Mei Chen
- The Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, BT9 7BL, UK.
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Liu YX, Sun WY, Xue B, Zhang RK, Li WJ, Xie X, Fan ZC. ARL3 mediates BBSome ciliary turnover by promoting its outward movement across the transition zone. J Cell Biol 2022; 221:213491. [PMID: 36129685 PMCID: PMC9499826 DOI: 10.1083/jcb.202111076] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 02/13/2022] [Accepted: 07/11/2022] [Indexed: 01/16/2023] Open
Abstract
Ciliary receptors and their certain downstream signaling components undergo intraflagellar transport (IFT) as BBSome cargoes to maintain their ciliary dynamics for sensing and transducing extracellular stimuli inside the cell. Cargo-laden BBSomes pass the transition zone (TZ) for ciliary retrieval, but how this passage is controlled remains elusive. Here, we show that phospholipase D (PLD)-laden BBSomes shed from retrograde IFT trains at the proximal ciliary region right above the TZ to act as Arf-like 3 (ARL3) GTPase-specific effectors in Chlamydomonas cilia. Under physiological condition, ARL3GDP binds to the membrane for diffusing into cilia. Following nucleotide exchange, ARL3GTP detaches from the ciliary membrane, binds to retrograde IFT train-shed and PLD-laden BBSomes at the proximal ciliary region right above the TZ, and recruits them to pass the TZ for ciliary retrieval likely via diffusion. ARL3 mediates the ciliary dynamics of certain signaling molecules through facilitating BBSome ciliary retrieval, providing a mechanistic understanding behind why ARL3-related Joubert syndrome shares overlapping phenotypes with Bardet-Biedl syndrome.
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Affiliation(s)
- Yan-Xia Liu
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Wei-Yue Sun
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Bin Xue
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Rui-Kai Zhang
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Wen-Juan Li
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Xixian Xie
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Zhen-Chuan Fan
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
- Correspondence to Zhen-Chuan Fan:
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A novel mutation located in the intermembrane space domain of AFG3L2 causes dominant optic atrophy through decreasing the stability of the encoded protein. Cell Death Dis 2022; 8:361. [PMID: 35970831 PMCID: PMC9378676 DOI: 10.1038/s41420-022-01160-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 08/03/2022] [Accepted: 08/04/2022] [Indexed: 11/18/2022]
Abstract
Dominant optic atrophy (DOA) is the most common hereditary optic neuropathy. Although DOA is caused by mutations in several genes, there are still many cases that have not been diagnosed or misdiagnosed. Herein, we present a large family of 11 patients with DOA. To identify potential pathogenic mutations, whole exome sequencing (WES) was performed on the proband, a 35-year-old woman. WES revealed a novel pathogenic mutation (c.524T>C, p.F175S) in the AFG3L2 intermembrane space domain, rather than in the ATPase domain, which is the hot mutation region associated with most of the previously reported DOA cases. Functional studies on skin fibroblasts generated from patients and HEK293T cells showed that the mutation may impair mitochondrial function and decrease the ability of AFG3L2 protein to enter the mitochondrial inner membrane. In addition, this novel mutation led to protein degradation and reduced the stability of the AFG3L2 protein, which appeared to be associated with the proteasome-ubiquitin pathway.
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Han J, Li Y, You Y, Fan K, Lei B. Autosomal dominant optic atrophy caused by six novel pathogenic OPA1 variants and genotype-phenotype correlation analysis. BMC Ophthalmol 2022; 22:322. [PMID: 35883160 PMCID: PMC9327245 DOI: 10.1186/s12886-022-02546-0] [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: 08/28/2021] [Accepted: 07/20/2022] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To describe the genetic and clinical features of nineteen patients from eleven unrelated Chinese pedigrees with OPA1-related autosomal dominant optic atrophy (ADOA) and define the phenotype-genotype correlations. METHODS Detailed ophthalmic examinations were performed. Targeted next-generation sequencing (NGS) was conducted in the eleven probands using a custom designed panel PS400. Sanger sequencing and cosegregation were used to verify the identified variants. The pathogenicity of gene variants was evaluated according to American College of Medical Genetics and Genomics (ACMG) guidelines. RESULTS Nineteen patients from the eleven unrelated Chinese ADOA pedigrees had impaired vision and optic disc pallor. Optical coherence tomography showed significant thinning of the retinal nerve fiber layer. The visual field showed varying degrees of central or paracentral scotoma. The onset of symptoms occurred between 3 and 24 years of age (median age 6 years). Eleven variants in OPA1 were identified in the cohort, and nine novel variants were identified. Among the novel variants, two splicing variants c.984 + 1_984 + 2delGT, c.1194 + 2 T > C, two stop-gain variants c.1937C > G, c.2830G > T, and one frameshift variant c.2787_2794del8, were determined to be pathogenic based on ACMG. A novel splicing variant c.1316-10 T > G was determined to be likely pathogenic. In addition, a novel missense c.1283A > C (p.N428T) and two novel splicing variants c.2496G > A and c.1065 + 5G > C were of uncertain significance. CONCLUSIONS Six novel pathogenic variants were identified. The findings will facilitate genetic counselling by expanding the pathogenic mutation spectrum of OPA1.
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Affiliation(s)
- Jinfeng Han
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China.,Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450000, China
| | - Ya Li
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China.,Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, 7 Weiwu Road, Zhengzhou, 450003, Henan, China
| | - Ya You
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China.,Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, 7 Weiwu Road, Zhengzhou, 450003, Henan, China
| | - Ke Fan
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China.,Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, 7 Weiwu Road, Zhengzhou, 450003, Henan, China
| | - Bo Lei
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China. .,Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450000, China. .,Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, 7 Weiwu Road, Zhengzhou, 450003, Henan, China.
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Bhardwaj A, Yadav A, Yadav M, Tanwar M. Genetic dissection of non-syndromic retinitis pigmentosa. Indian J Ophthalmol 2022; 70:2355-2385. [PMID: 35791117 PMCID: PMC9426071 DOI: 10.4103/ijo.ijo_46_22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Retinitis pigmentosa (RP) belongs to a group of pigmentary retinopathies. It is the most common form of inherited retinal dystrophy, characterized by progressive degradation of photoreceptors that leads to nyctalopia, and ultimately, complete vision loss. RP is distinguished by the continuous retinal degeneration that progresses from the mid-periphery to the central and peripheral retina. RP was first described and named by Franciscus Cornelius Donders in the year 1857. It is one of the leading causes of bilateral blindness in adults, with an incidence of 1 in 3000 people worldwide. In this review, we are going to focus on the genetic heterogeneity of this disease, which is provided by various inheritance patterns, numerosity of variations and inter-/intra-familial variations based upon penetrance and expressivity. Although over 90 genes have been identified in RP patients, the genetic cause of approximately 50% of RP cases remains unknown. Heterogeneity of RP makes it an extremely complicated ocular impairment. It is so complicated that it is known as “fever of unknown origin”. For prognosis and proper management of the disease, it is necessary to understand its genetic heterogeneity so that each phenotype related to the various genetic variations could be treated.
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Affiliation(s)
- Aarti Bhardwaj
- Department of Genetics, M. D. University, Rohtak, Haryana, India
| | - Anshu Yadav
- Department of Genetics, M. D. University, Rohtak, Haryana, India
| | - Manoj Yadav
- Department of Genetics, M. D. University, Rohtak, Haryana, India
| | - Mukesh Tanwar
- Department of Genetics, M. D. University, Rohtak, Haryana, India
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Guo Q, Li Y, Li J, You Y, Liu C, Chen K, Li S, Lei B. Phenotype Heterogeneity and the Association Between Visual Acuity and Outer Retinal Structure in a Cohort of Chinese X-Linked Juvenile Retinoschisis Patients. Front Genet 2022; 13:832814. [PMID: 35309139 PMCID: PMC8931683 DOI: 10.3389/fgene.2022.832814] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 02/03/2022] [Indexed: 11/24/2022] Open
Abstract
Purpose: X-linked juvenile retinoschisis (XLRS), caused by mutations in the RS1 gene, is an X-linked recessive inherited disease that typically involves both eyes in the first 2 decades of life. Recently, the phenotype heterogeneity of this condition has drawn increasing attention. We reported various phenotypes caused by RS1 gene mutations in eleven patients from ten Chinese families. Methods: Data on the medical history of the patients from ten Han families of central China were collected. Ophthalmic examinations including best-corrected visual acuity (BCVA), fundus photography, ultra-wide-angle sweep source optical coherence tomography (SS-OCT), and electroretinography (ERG) were performed. Adaptive optics (AO) images were acquired to evaluate the cone photoreceptor mosaic when applicable. Venous blood of the probands and their family members was collected, and DNA was subjected to sequencing based on next-generation sequencing with a custom-designed targeted gene panel PS400 for inherited retinal diseases. Validation was performed by Sanger sequencing and cosegregation. Pathogenicity was determined in accordance with the American College of Medical Genetics and Genomics (ACMG) guidelines. Results: Ten RS1 mutations, including eight missense mutations and two terminator mutations, were identified in 10 XLRS families. c.657C > A (p.C219X) was a novel mutation in this cohort. These patients showed a variety of clinical phenotypes, including fovea schisis, bullous retinoschisis, and macular or peripheral atrophy. Fifteen eyes of eight patients exhibited macular retinoschisis, and twelve eyes of seven patients exhibited peripheral retinoschisis. In addition, three patients showed asymmetrical fundus manifestations. Of importance, three patients without macular retinoschisis were misdiagnosed until genetic testing results were obtained. AO showed a decrease in cone density and loss of regularity in the cystic schisis macular of XLRS. Furthermore, the BCVA was associated with the photoreceptor inner segment and outer segment (IS/OS) thickness. Conclusion: With complicated clinical manifestations, a considerable portion of XLRS patients may present various phenotypes. It should be noted that asymmetry in fundus appearance in both eyes could lead to misdiagnosis easily. Thus, genetic testing is crucial for making a final diagnosis in those patients who are suspected of having amblyopia, bilateral or unilateral macular atrophy, or conditions presenting an asymmetric fundus appearance. In addition, the residual cone photoreceptor structure was critical for the maintenance of useful vision.
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Affiliation(s)
- Qingge Guo
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
- Henan Clinical Research Center for Ocular Diseases, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Ya Li
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
- Henan Clinical Research Center for Ocular Diseases, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Jiarui Li
- School of Medicine, People’s Hospital of Henan University, Henan University, Zhengzhou, China
| | - Ya You
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
- Henan Clinical Research Center for Ocular Diseases, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Changgeng Liu
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
- Henan Clinical Research Center for Ocular Diseases, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Kang Chen
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
- Henan Clinical Research Center for Ocular Diseases, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Shuyin Li
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
- Henan Clinical Research Center for Ocular Diseases, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Bo Lei
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
- Henan Clinical Research Center for Ocular Diseases, People’s Hospital of Zhengzhou University, Zhengzhou, China
- School of Medicine, People’s Hospital of Henan University, Henan University, Zhengzhou, China
- *Correspondence: Bo Lei,
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Ratnapriya R, Jacobson SG, Cideciyan AV, English MA, Roman AJ, Sumaroka A, Sheplock R, Swaroop A. A Novel ARL3 Gene Mutation Associated With Autosomal Dominant Retinal Degeneration. Front Cell Dev Biol 2021; 9:720782. [PMID: 34485303 PMCID: PMC8416110 DOI: 10.3389/fcell.2021.720782] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 07/07/2021] [Indexed: 12/18/2022] Open
Abstract
Despite major progress in the discovery of causative genes, many individuals and families with inherited retinal degenerations (IRDs) remain without a molecular diagnosis. We applied whole exome sequencing to identify the genetic cause in a family with an autosomal dominant IRD. Eye examinations were performed and affected patients were studied with electroretinography and kinetic and chromatic static perimetry. Sequence variants were analyzed in genes (n = 271) associated with IRDs listed on the RetNet database. We applied a stepwise filtering process involving the allele frequency in the control population, in silico prediction tools for pathogenicity, and evolutionary conservation to prioritize the potential causal variant(s). Sanger sequencing and segregation analysis were performed on the proband and other family members. The IRD in this family is expressed as a widespread progressive retinal degeneration with maculopathy. A novel heterozygous variant (c.200A > T) was identified in the ARL3 gene, leading to the substitution of aspartic acid to valine at position 67. The Asp67 residue is evolutionary conserved, and the change p.Asp67Val is predicted to be pathogenic. This variant was segregated in affected members of the family and was absent from an unaffected individual. Two previous reports of a de novo missense mutation in the ARL3 gene, each describing a family with two affected generations, are the only examples to date of autosomal dominant IRD associated with this photoreceptor gene. Our results, identifying a novel pathogenic variant in ARL3 in a four-generation family with a dominant IRD, augment the evidence that the ARL3 gene is another cause of non-syndromic retinal degeneration.
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Affiliation(s)
- Rinki Ratnapriya
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, United States.,Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
| | - Samuel G Jacobson
- Department of Ophthalmology, Perelman School of Medicine, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Artur V Cideciyan
- Department of Ophthalmology, Perelman School of Medicine, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Milton A English
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Alejandro J Roman
- Department of Ophthalmology, Perelman School of Medicine, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Alexander Sumaroka
- Department of Ophthalmology, Perelman School of Medicine, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Rebecca Sheplock
- Department of Ophthalmology, Perelman School of Medicine, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Anand Swaroop
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
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