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Leung M, Steinman J, Li D, Lor A, Gruesen A, Sadah A, van Kuijk FJ, Montezuma SR, Kondkar AA, Radhakrishnan R, Lobo GP. The Logistical Backbone of Photoreceptor Cell Function: Complementary Mechanisms of Dietary Vitamin A Receptors and Rhodopsin Transporters. Int J Mol Sci 2024; 25:4278. [PMID: 38673863 PMCID: PMC11050646 DOI: 10.3390/ijms25084278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024] Open
Abstract
In this review, we outline our current understanding of the mechanisms involved in the absorption, storage, and transport of dietary vitamin A to the eye, and the trafficking of rhodopsin protein to the photoreceptor outer segments, which encompasses the logistical backbone required for photoreceptor cell function. Two key mechanisms of this process are emphasized in this manuscript: ocular and systemic vitamin A membrane transporters, and rhodopsin transporters. Understanding the complementary mechanisms responsible for the generation and proper transport of the retinylidene protein to the photoreceptor outer segment will eventually shed light on the importance of genes encoded by these proteins, and their relationship on normal visual function and in the pathophysiology of retinal degenerative diseases.
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Affiliation(s)
- Matthias Leung
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Jeremy Steinman
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Dorothy Li
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Anjelynt Lor
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Andrew Gruesen
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Ahmed Sadah
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Frederik J. van Kuijk
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Sandra R. Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Altaf A. Kondkar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh 12271, Saudi Arabia;
| | - Rakesh Radhakrishnan
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Glenn P. Lobo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
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2
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Zhang Z, Moye AR, He F, Chen M, Agosto MA, Wensel TG. Centriole and transition zone structures in photoreceptor cilia revealed by cryo-electron tomography. Life Sci Alliance 2024; 7:e202302409. [PMID: 38182160 PMCID: PMC10770417 DOI: 10.26508/lsa.202302409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 12/12/2023] [Accepted: 12/12/2023] [Indexed: 01/07/2024] Open
Abstract
Primary cilia mediate sensory signaling in multiple organisms and cell types but have structures adapted for specific roles. Structural defects in them lead to devastating diseases known as ciliopathies in humans. Key to their functions are structures at their base: the basal body, the transition zone, the "Y-shaped links," and the "ciliary necklace." We have used cryo-electron tomography with subtomogram averaging and conventional transmission electron microscopy to elucidate the structures associated with the basal region of the "connecting cilia" of rod outer segments in mouse retina. The longitudinal variations in microtubule (MT) structures and the lumenal scaffold complexes connecting them have been determined, as well as membrane-associated transition zone structures: Y-shaped links connecting MT to the membrane, and ciliary beads connected to them that protrude from the cell surface and form a necklace-like structure. These results represent a clearer structural scaffold onto which molecules identified by genetics, proteomics, and superresolution fluorescence can be placed in our emerging model of photoreceptor sensory cilia.
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Affiliation(s)
- Zhixian Zhang
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Abigail R Moye
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
- Department of Ophthalmic Genetics, Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
| | - Feng He
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Muyuan Chen
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, USA
| | - Melina A Agosto
- Department of Physiology and Biophysics and Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada
| | - Theodore G Wensel
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
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Clark AM, Yu D, Neiswanger G, Zhu D, Zou J, Maschek JA, Burgoyne T, Yang J. Disruption of CFAP418 interaction with lipids causes widespread abnormal membrane-associated cellular processes in retinal degenerations. JCI Insight 2024; 9:e162621. [PMID: 37971880 PMCID: PMC10906455 DOI: 10.1172/jci.insight.162621] [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: 06/13/2022] [Accepted: 11/15/2023] [Indexed: 11/19/2023] Open
Abstract
Syndromic ciliopathies and retinal degenerations are large heterogeneous groups of genetic diseases. Pathogenic variants in the CFAP418 gene may cause both disorders, and its protein sequence is evolutionarily conserved. However, the disease mechanism underlying CFAP418 mutations has not been explored. Here, we apply quantitative lipidomic, proteomic, and phosphoproteomic profiling and affinity purification coupled with mass spectrometry to address the molecular function of CFAP418 in the retina. We show that CFAP418 protein binds to the lipid metabolism precursor phosphatidic acid (PA) and mitochondrion-specific lipid cardiolipin but does not form a tight and static complex with proteins. Loss of Cfap418 in mice disturbs membrane lipid homeostasis and membrane-protein associations, which subsequently causes mitochondrial defects and membrane-remodeling abnormalities across multiple vesicular trafficking pathways in photoreceptors, especially the endosomal sorting complexes required for transport (ESCRT) pathway. Ablation of Cfap418 also increases the activity of PA-binding protein kinase Cα in the retina. Overall, our results indicate that membrane lipid imbalance is a pathological mechanism underlying syndromic ciliopathies and retinal degenerations which is associated with other known causative genes of these diseases.
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Affiliation(s)
- Anna M. Clark
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, and
| | - Dongmei Yu
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, and
| | - Grace Neiswanger
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, and
| | - Daniel Zhu
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, and
| | - Junhuang Zou
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, and
| | - J. Alan Maschek
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
| | - Thomas Burgoyne
- UCL Institute of Ophthalmology, University College of London, London, United Kingdom
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, and
- Department of Otolaryngology, and
- Department of Neurobiology, University of Utah, Salt Lake City, Utah, USA
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Liu J, Xie H, Wu M, Hu Y, Kang Y. The role of cilia during organogenesis in zebrafish. Open Biol 2023; 13:230228. [PMID: 38086423 PMCID: PMC10715920 DOI: 10.1098/rsob.230228] [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: 07/18/2023] [Accepted: 11/03/2023] [Indexed: 12/18/2023] Open
Abstract
Cilia are hair-like organelles that protrude from the surface of eukaryotic cells and are present on the surface of nearly all human cells. Cilia play a crucial role in signal transduction, organ development and tissue homeostasis. Abnormalities in the structure and function of cilia can lead to a group of human diseases known as ciliopathies. Currently, zebrafish serves as an ideal model for studying ciliary function and ciliopathies due to its relatively conserved structure and function of cilia compared to humans. In this review, we will summarize the different types of cilia that present in embryonic and adult zebrafish, and provide an overview of the advantages of using zebrafish as a vertebrate model for cilia research. We will specifically focus on the roles of cilia during zebrafish organogenesis based on recent studies. Additionally, we will highlight future prospects for ciliary research in zebrafish.
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Affiliation(s)
- Junjun Liu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
| | - Haibo Xie
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
| | - Mengfan Wu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
| | - Yidan Hu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
| | - Yunsi Kang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
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Pan H, Qin Y, Zhu J, Wang W, Liu Z, Huang X, Lam SM, Shui G, Wang Y, Jiang Y, Huang X. Centrins control chicken cone cell lipid droplet dynamics through lipid-droplet-localized SPDL1. Dev Cell 2023; 58:2528-2544.e8. [PMID: 37699389 DOI: 10.1016/j.devcel.2023.08.012] [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: 07/30/2022] [Revised: 05/10/2023] [Accepted: 08/08/2023] [Indexed: 09/14/2023]
Abstract
As evolutionarily conserved organelles, lipid droplets (LDs) carry out numerous functions and have various subcellular localizations in different cell types and species. In avian cone cells, there is a single apically localized LD. We demonstrated that CIDEA (cell death inducing DFFA like effector a) and microtubules promote the formation of the single LD in chicken cone cells. Centrins, which are well-known centriole proteins, target to the cone cell LD via their C-terminal calcium-binding domains. Centrins localize on cone cell LDs with the help of SPDL1-L (spindle apparatus coiled-coil protein 1-L), a previously uncharacterized isoform of the kinetochore-associated dynein adaptor SPDL1. The loss of CETN3 or overexpression of a truncated CETN1 abrogates the apical localization of the cone cell LD. Simulation analysis showed that multiple LDs or a single mispositioned LD reduces the light sensitivity. Collectively, our findings identify a role of centrins in the regulation of cone cell LD localization, which is important for the light sensitivity of cone cells.
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Affiliation(s)
- Huimin Pan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yaqiang Qin
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinglin Zhu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhonghua Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiahe Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sin Man Lam
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuqiang Jiang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Tianjian Laboratory of Advanced Biomedical Sciences, Zhengzhou 450001, China.
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Masek M, Bachmann-Gagescu R. Control of protein and lipid composition of photoreceptor outer segments-Implications for retinal disease. Curr Top Dev Biol 2023; 155:165-225. [PMID: 38043951 DOI: 10.1016/bs.ctdb.2023.09.001] [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] [Indexed: 12/05/2023]
Abstract
Vision is arguably our most important sense, and its loss brings substantial limitations to daily life for affected individuals. Light is perceived in retinal photoreceptors (PRs), which are highly specialized neurons subdivided into several compartments with distinct functions. The outer segments (OSs) of photoreceptors represent highly specialized primary ciliary compartments hosting the phototransduction cascade, which transforms incoming light into a neuronal signal. Retinal disease can result from various pathomechanisms originating in distinct subcompartments of the PR cell, or in the retinal pigment epithelium which supports the PRs. Dysfunction of primary cilia causes human disorders known as "ciliopathies", in which retinal disease is a common feature. This chapter focuses on PR OSs, discussing the mechanisms controlling their complex structure and composition. A sequence of tightly regulated sorting and trafficking events, both upstream of and within this ciliary compartment, ensures the establishment and maintenance of the adequate proteome and lipidome required for signaling in response to light. We discuss in particular our current understanding of the role of ciliopathy proteins involved in multi-protein complexes at the ciliary transition zone (CC2D2A) or BBSome (BBS1) and how their dysfunction causes retinal disease. While the loss of CC2D2A prevents the fusion of vesicles and delivery of the photopigment rhodopsin to the ciliary base, leading to early OS ultrastructural defects, BBS1 deficiency results in precocious accumulation of cholesterol in mutant OSs and decreased visual function preceding morphological changes. These distinct pathomechanisms underscore the central role of ciliary proteins involved in multiple processes controlling OS protein and lipid composition.
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Affiliation(s)
- Markus Masek
- Institute of Medical Genetics, University of Zurich, Zurich, Switzerland; Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Ruxandra Bachmann-Gagescu
- Institute of Medical Genetics, University of Zurich, Zurich, Switzerland; Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland; University Research Priority Program AdaBD, University of Zurich, Zurich, Switzerland.
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Xiang L, Yang QL, Xie BT, Zeng HY, Ding LJ, Rao FQ, Yan T, Lu F, Chen Q, Huang XF. Dysregulated Arginine Metabolism Is Linked to Retinal Degeneration in Cep250 Knockout Mice. Invest Ophthalmol Vis Sci 2023; 64:2. [PMID: 37656476 PMCID: PMC10479211 DOI: 10.1167/iovs.64.12.2] [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: 03/06/2023] [Accepted: 08/04/2023] [Indexed: 09/02/2023] Open
Abstract
Purpose Degeneration of retinal photoreceptors is frequently observed in diverse ciliopathy disorders, and photoreceptor cilium gates the molecular trafficking between the inner and the outer segment (OS). This study aims to generate a homozygous global Cep250 knockout (KO) mouse and study the resulting phenotype. Methods We used Cep250 KO mice and untargeted metabolomics to uncover potential mechanisms underlying retinal degeneration. Long-term follow-up studies using optical coherence tomography (OCT) and electroretinography (ERG) were performed. Results OCT and ERG results demonstrated gradual thinning of the outer nuclear layer (ONL) and progressive attenuation of the scotopic ERG responses in Cep250-/- mice. More TUNEL signal was observed in the ONL of these mice. Immunostaining of selected OS proteins revealed mislocalization of these proteins in the ONL of Cep250-/- mice. Interestingly, untargeted metabolomics analysis revealed arginine-related metabolic pathways were altered and enriched in Cep250-/- mice. Mis-localization of a key protein in the arginine metabolism pathway, arginase 1 (ARG1), in the ONL of KO mice further supports this model. Moreover, adeno-associated virus (AAV)-based retinal knockdown of Arg1 led to similar architectural and functional alterations in wild-type retinas. Conclusions Altogether, these results suggest that dysregulated arginine metabolism contributes to retinal degeneration in Cep250-/- mice. Our findings provide novel insights that increase understanding of retinal degeneration in ciliopathy disorders.
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Affiliation(s)
- Lue Xiang
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qiao-Li Yang
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Bin-Tao Xie
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Hui-Yi Zeng
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Liu-Jun Ding
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Feng-Qin Rao
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
- School of Pharmaceutical Sciences of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Tong Yan
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Fan Lu
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qi Chen
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xiu-Feng Huang
- Zhejiang Provincial Clinical Research Center for Pediatric Disease, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
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Zufiaurre-Seijo M, García-Arumí J, Duarri A. Clinical and Molecular Aspects of C2orf71/PCARE in Retinal Diseases. Int J Mol Sci 2023; 24:10670. [PMID: 37445847 DOI: 10.3390/ijms241310670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Mutations in the photoreceptor-specific C2orf71 gene (also known as photoreceptor cilium actin regulator protein PCARE) cause autosomal recessive retinitis pigmentosa type 54 and cone-rod dystrophy. No treatments are available for patients with C2orf71 retinal ciliopathies exhibiting a severe clinical phenotype. Our understanding of the disease process and the role of PCARE in the healthy retina significantly limits our capacity to transfer recent technical developments into viable therapy choices. This study summarizes the current understanding of C2orf71-related retinal diseases, including their clinical manifestations and an unclear genotype-phenotype correlation. It discusses molecular and functional studies on the photoreceptor-specific ciliary PCARE, focusing on the photoreceptor cell and its ciliary axoneme. It is proposed that PCARE is an actin-associated protein that interacts with WASF3 to regulate the actin-driven expansion of the ciliary membrane during the development of a new outer segment disk in photoreceptor cells. This review also introduces various cellular and animal models used to model these diseases and provides an overview of potential treatments.
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Affiliation(s)
- Maddalen Zufiaurre-Seijo
- Ophthalmology Research Group, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, 08035 Barcelona, Spain
| | - José García-Arumí
- Ophthalmology Research Group, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, 08035 Barcelona, Spain
| | - Anna Duarri
- Ophthalmology Research Group, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, 08035 Barcelona, Spain
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Swinkels D, Baes M. The essential role of docosahexaenoic acid and its derivatives for retinal integrity. Pharmacol Ther 2023; 247:108440. [PMID: 37201739 DOI: 10.1016/j.pharmthera.2023.108440] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/08/2023] [Accepted: 05/15/2023] [Indexed: 05/20/2023]
Abstract
The fatty acid composition of photoreceptor outer segment (POS) phospholipids diverges from other membranes, being highly enriched in polyunsaturated fatty acids (PUFAs). The most abundant PUFA is docosahexaenoic acid (DHA, C22:6n-3), an omega-3 PUFA that amounts to over 50% of the POS phospholipid fatty acid side chains. Interestingly, DHA is the precursor of other bioactive lipids such as elongated PUFAs and oxygenated derivatives. In this review, we present the current view on metabolism, trafficking and function of DHA and very long chain polyunsaturated fatty acids (VLC-PUFAs) in the retina. New insights on pathological features generated from PUFA deficient mouse models with enzyme or transporter defects and corresponding patients are discussed. Not only the neural retina, but also abnormalities in the retinal pigment epithelium are considered. Furthermore, the potential involvement of PUFAs in more common retinal degeneration diseases such as diabetic retinopathy, retinitis pigmentosa and age-related macular degeneration are evaluated. Supplementation treatment strategies and their outcome are summarized.
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Affiliation(s)
- Daniëlle Swinkels
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Myriam Baes
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium.
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10
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Gerstner CD, Reed M, Dahl TM, Ying G, Frederick JM, Baehr W. Arf-like Protein 2 (ARL2) Controls Microtubule Neogenesis during Early Postnatal Photoreceptor Development. Cells 2022; 12:147. [PMID: 36611941 PMCID: PMC9818799 DOI: 10.3390/cells12010147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/12/2022] [Accepted: 12/21/2022] [Indexed: 12/31/2022] Open
Abstract
Arf-like protein 2 (ARL2) is a ubiquitously expressed small GTPase with multiple functions. In a cell culture, ARL2 participates with tubulin cofactor D (TBCD) in the neogenesis of tubulin αβ-heterodimers, the building blocks of microtubules. To evaluate this function in the retina, we conditionally deleted ARL2 in mouse retina at two distinct stages, either during the embryonic development (retArl2-/-) or after ciliogenesis specifically in rods (rodArl2-/-). retArl2-/- retina sections displayed distorted nuclear layers and a disrupted microtubule cytoskeleton (MTC) as early as postnatal day 6 (P6). Rod and cone outer segments (OS) did not form. By contrast, the rod ARL2 knockouts were stable at postnatal day 35 and revealed normal ERG responses. Cytoplasmic dynein is reduced in retArl2-/- inner segments (IS), suggesting that dynein may be unstable in the absence of a normal MTC. We investigated the microtubular stability in the absence of either ARL2 (retARL2-/-) or DYNC1H1 (retDync1h1-/-), the dynein heavy chain, and found that both the retArl2-/- and retDync1h1-/- retinas exhibited reduced microtubules and nuclear layer distortion. The results suggest that ARL2 and dynein depend on each other to generate a functional MTC during the early photoreceptor development.
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Affiliation(s)
- Cecilia D. Gerstner
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, UT 84132, USA
| | - Michelle Reed
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, UT 84132, USA
| | - Tiffanie M. Dahl
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, UT 84132, USA
| | - Guoxin Ying
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, UT 84132, USA
| | - Jeanne M. Frederick
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, UT 84132, USA
| | - Wolfgang Baehr
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, UT 84132, USA
- Department of Neurobiology & Anatomy, University of Utah, Salt Lake City, UT 84112, USA
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
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Park K, Leroux MR. Composition, organization and mechanisms of the transition zone, a gate for the cilium. EMBO Rep 2022; 23:e55420. [PMID: 36408840 PMCID: PMC9724682 DOI: 10.15252/embr.202255420] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 08/08/2022] [Accepted: 10/31/2022] [Indexed: 11/22/2022] Open
Abstract
The cilium evolved to provide the ancestral eukaryote with the ability to move and sense its environment. Acquiring these functions required the compartmentalization of a dynein-based motility apparatus and signaling proteins within a discrete subcellular organelle contiguous with the cytosol. Here, we explore the potential molecular mechanisms for how the proximal-most region of the cilium, termed transition zone (TZ), acts as a diffusion barrier for both membrane and soluble proteins and helps to ensure ciliary autonomy and homeostasis. These include a unique complement and spatial organization of proteins that span from the microtubule-based axoneme to the ciliary membrane; a protein picket fence; a specialized lipid microdomain; differential membrane curvature and thickness; and lastly, a size-selective molecular sieve. In addition, the TZ must be permissive for, and functionally integrates with, ciliary trafficking systems (including intraflagellar transport) that cross the barrier and make the ciliary compartment dynamic. The quest to understand the TZ continues and promises to not only illuminate essential aspects of human cell signaling, physiology, and development, but also to unravel how TZ dysfunction contributes to ciliopathies that affect multiple organ systems, including eyes, kidney, and brain.
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Affiliation(s)
- Kwangjin Park
- Department of Molecular Biology and BiochemistrySimon Fraser UniversityBurnabyBCCanada
- Centre for Cell Biology, Development, and DiseaseSimon Fraser UniversityBurnabyBCCanada
- Present address:
Terry Fox LaboratoryBC CancerVancouverBCCanada
- Present address:
Department of Medical GeneticsUniversity of British ColumbiaVancouverBCCanada
| | - Michel R Leroux
- Department of Molecular Biology and BiochemistrySimon Fraser UniversityBurnabyBCCanada
- Centre for Cell Biology, Development, and DiseaseSimon Fraser UniversityBurnabyBCCanada
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12
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Reed M, Takemaru KI, Ying G, Frederick JM, Baehr W. Deletion of CEP164 in mouse photoreceptors post-ciliogenesis interrupts ciliary intraflagellar transport (IFT). PLoS Genet 2022; 18:e1010154. [PMID: 36074756 PMCID: PMC9488791 DOI: 10.1371/journal.pgen.1010154] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 09/20/2022] [Accepted: 07/20/2022] [Indexed: 11/18/2022] Open
Abstract
Centrosomal protein of 164 kDa (CEP164) is located at distal appendages of primary cilia and is necessary for basal body (BB) docking to the apical membrane. To investigate the function of photoreceptor CEP164 before and after BB docking, we deleted CEP164 during retina embryonic development (Six3Cre), in postnatal rod photoreceptors (iCre75) and in mature retina using tamoxifen induction (Prom1-ETCre). BBs dock to the cell cortex during postnatal day 6 (P6) to extend a connecting cilium (CC) and an axoneme. P6 retina-specific knockouts (retCep164-/-) are unable to dock BBs, thereby preventing formation of CC or outer segments (OSs). In rod-specific knockouts (rodCep164-/-), Cre expression starts after P7 and CC/OS form. P16 rodCep164-/- rods have nearly normal OS lengths, and maintain OS attachment through P21 despite loss of CEP164. Intraflagellar transport components (IFT88, IFT57 and IFT140) were reduced at P16 rodCep164-/- BBs and CC tips and nearly absent at P21, indicating impaired intraflagellar transport. Nascent OS discs, labeled with a fluorescent dye on P14 and P18 and harvested on P19, showed continued rodCep164-/- disc morphogenesis but absence of P14 discs mid-distally, indicating OS instability. Tamoxifen induction with PROM1ETCre;Cep164F/F (tamCep164-/-) adult mice affected maintenance of both rod and cone OSs. The results suggest that CEP164 is key towards recruitment and stabilization of IFT-B particles at the BB/CC. IFT impairment may be the main driver of ciliary malfunction observed with hypomorphic CEP164 mutations.
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Affiliation(s)
- Michelle Reed
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah, United States of America
| | - Ken-Ichi Takemaru
- Stony Brook University, Department of Pharmacological Sciences, Stony Brook, New York, United States of America
| | - Guoxin Ying
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah, United States of America
| | - Jeanne M. Frederick
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah, United States of America
| | - Wolfgang Baehr
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah, United States of America
- Department of Neurobiology & Anatomy, University of Utah, Salt Lake City, Utah, United States of America
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
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13
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Yang Y, Shuai P, Li X, Sun K, Jiang X, Liu W, Le W, Jiang H, Liu Y, Zhu X. Mettl14-mediated m6A modification is essential for visual function and retinal photoreceptor survival. BMC Biol 2022; 20:140. [PMID: 35698136 PMCID: PMC9195452 DOI: 10.1186/s12915-022-01335-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 05/18/2022] [Indexed: 12/13/2022] Open
Abstract
Background As the most abundant epigenetic modification of eukaryotic mRNA, N6-methyladenosine (m6A) modification has been shown to play a role in mammalian nervous system development and function by regulating mRNA synthesis and degeneration. However, the role of m6A modification in retinal photoreceptors remains unknown. Results We generated the first retina-specific Mettl14-knockout mouse models using the Rho-Cre and HRGP-Cre lines and investigated the functions of Mettl14 in retinal rod and cone photoreceptors. Our data showed that loss of Mettl14 in rod cells causes a weakened scotopic photoresponse and rod degeneration. Further study revealed the ectopic accumulation of multiple outer segment (OS) proteins in the inner segment (IS). Deficiency of Mettl14 in cone cells led to the mislocalization of cone opsin proteins and the progressive death of cone cells. Moreover, Mettl14 depletion resulted in drastic decreases in METTL3/WTAP levels and reduced m6A methylation levels. Mechanistically, transcriptomic analyses in combination with MeRIP-seq illustrated that m6A depletion via inactivation of Mettl14 resulted in reduced expression levels of multiple phototransduction- and cilium-associated genes, which subsequently led to compromised ciliogenesis and impaired synthesis and transport of OS-residing proteins in rod cells. Conclusions Our data demonstrate that Mettl14 plays an important role in regulating phototransduction and ciliogenesis events and is essential for photoreceptor function and survival, highlighting the importance of m6A modification in visual function. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01335-x.
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Affiliation(s)
- Yeming Yang
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 61007, Sichuan, China.,The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, Sichuan, China.,Key Laboratory of Tibetan Medicine Research, Chinese Academy of Sciences and Qinghai Provincial Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Xining, 810008, Qinghai, China
| | - Ping Shuai
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 61007, Sichuan, China.,The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, Sichuan, China
| | - Xiao Li
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 61007, Sichuan, China.,The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, Sichuan, China
| | - Kuanxiang Sun
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 61007, Sichuan, China
| | - Xiaoyan Jiang
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 61007, Sichuan, China
| | - Wenjing Liu
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 61007, Sichuan, China
| | - Weidong Le
- Institute of Neurology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, Sichuan, China.,Department of Neurology, Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Haisong Jiang
- Institute of Neurology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, Sichuan, China. .,Department of Neurology, Sichuan Provincial People's Hospital, Chengdu, Sichuan, China.
| | - Yuping Liu
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 61007, Sichuan, China.
| | - Xianjun Zhu
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 61007, Sichuan, China. .,The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, Sichuan, China. .,Key Laboratory of Tibetan Medicine Research, Chinese Academy of Sciences and Qinghai Provincial Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Xining, 810008, Qinghai, China. .,Research Unit for Blindness Prevention of the Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, 610072, Sichuan, China. .,Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, 450003, Henan, China.
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14
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Li M, Xu J, Wang Y, Du X, Zhang T, Chen Y. Astragaloside A Protects Against Photoreceptor Degeneration in Part Through Suppressing Oxidative Stress and DNA Damage-Induced Necroptosis and Inflammation in the Retina. J Inflamm Res 2022; 15:2995-3020. [PMID: 35645574 PMCID: PMC9130102 DOI: 10.2147/jir.s362401] [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: 02/19/2022] [Accepted: 05/13/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose Photoreceptors are specialized retinal neurons responsible for phototransduction. Loss of photoreceptors directly leads to irreversible vision impairment. Pharmacological therapies protecting against photoreceptor degeneration are clinically lacking. Oxidative stress and inflammation are common mechanisms playing important roles in the pathogenesis of photoreceptor degeneration. Astragaloside A (AS-A) is a naturally occurring antioxidant and anti-inflammatory agent with neuroprotective activities. However, the photoreceptor protective effects of AS-A remain unknown. The current study thus aims to illustrate the pharmacological potentials of AS-A in protecting against photoreceptor degeneration. Methods BALB/c and C57/BL6J mice were exposed to bright light and DNA alkylating agent methyl methanesulfonate (MMS) to develop oxidative stress and DNA damage-mediated photoreceptor degeneration, respectively. Microstructural, morphological and functional assessments were performed to directly evaluate the photoreceptor protective effects of AS-A. Ultrastructural and molecular changes in the retina were examined to better understand the pharmacological mechanisms of AS-A in protecting against photoreceptor degeneration. Results AS-A protected against bright light-induced photoreceptor impairment. Bright light-induced retinal oxidative stress and photoreceptor cell death were attenuated by AS-A treatment. AS-A treatment mitigated bright light-induced DNA damage, activation of poly (ADP-ribose) polymerase (PARP) and nuclear dislocation of high mobility group box 1 (HMGB1) in photoreceptors. AS-A broadly counteracted bright light-altered retinal gene expression profiles. In particular, AS-A decreased the retinal expression of genes involved in necroptosis and inflammatory responses. Bright light-induced microglial activation was also suppressed as a result of AS-A treatment. Furthermore, AS-A attenuated MMS-induced photoreceptor morphological impairment, elevated expression of pro-necroptotic and proinflammatory genes as well as microglial activation in the retina. Conclusion The work here demonstrates for the first time that AS-A protects against photoreceptor degeneration in part through mitigating oxidative stress and DNA damage-induced necroptosis and inflammatory responses in the retina.
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Affiliation(s)
- Mei Li
- Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 200427, People's Republic of China
| | - Jing Xu
- Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 200427, People's Republic of China.,Clinical Research Institute of Integrative Medicine, Shanghai Academy of Traditional Chinese Medicine, Shanghai, 200437, People's Republic of China
| | - Yujue Wang
- Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 200427, People's Republic of China
| | - Xiaoye Du
- Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 200427, People's Republic of China.,Clinical Research Institute of Integrative Medicine, Shanghai Academy of Traditional Chinese Medicine, Shanghai, 200437, People's Republic of China
| | - Teng Zhang
- Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 200427, People's Republic of China.,Clinical Research Institute of Integrative Medicine, Shanghai Academy of Traditional Chinese Medicine, Shanghai, 200437, People's Republic of China
| | - Yu Chen
- Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 200427, People's Republic of China.,Clinical Research Institute of Integrative Medicine, Shanghai Academy of Traditional Chinese Medicine, Shanghai, 200437, People's Republic of China.,Laboratory of Clinical and Molecular Pharmacology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 200427, People's Republic of China
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15
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Tmem138 is localized to the connecting cilium essential for rhodopsin localization and outer segment biogenesis. Proc Natl Acad Sci U S A 2022; 119:e2109934119. [PMID: 35394880 PMCID: PMC9169668 DOI: 10.1073/pnas.2109934119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The connecting cilium (CC) of the photoreceptor provides the only route for the trafficking of the outer segment (OS) proteins. Failure of OS protein transport causes degenerative photoreceptor diseases, including retinitis pigmentosa. We demonstrate that Tmem138, a protein linked to ciliopathy, is localized to the photoreceptor CC. Germline deletion of Tmem138 abolished OS morphogenesis, followed by rapid photoreceptor degeneration. Tmem138 interacts with rhodopsin and two additional CC compartment proteins, Ahi1 and Tmem231, likely forming a membrane complex to facilitate trafficking of rhodopsin and other OS-bound proteins across the CC. The study thus implicates a new line of regulation on the delivery of OS proteins through interactions with CC membrane complex(es) and provides insights into photoreceptor ciliopathy diseases. Photoreceptor connecting cilium (CC) is structurally analogous to the transition zone (TZ) of primary cilia and gates the molecular trafficking between the inner and the outer segment (OS). Retinal dystrophies with underlying CC defects are manifested in a broad array of syndromic conditions known as ciliopathies as well as nonsyndromic retinal degenerations. Despite extensive studies, many questions remain in the mechanism of protein trafficking across the photoreceptor CC. Here, we genetically inactivated mouse Tmem138, a gene encoding a putative transmembrane protein localized to the ciliary TZ and linked to ciliopathies. Germline deletion of Tmem138 abolished OS morphogenesis, followed by rapid photoreceptor degeneration. Tmem138 was found localized to the photoreceptor CC and was required for localization of Ahi1 to the distal subdomain of the CC. Among the examined set of OS proteins, rhodopsin was mislocalized throughout the mutant cell body prior to OS morphogenesis. Ablation of Tmem138 in mature rods recapitulated the molecular changes in the germline mutants, causing failure of disc renewal and disintegration of the OS. Furthermore, Tmem138 interacts reciprocally with rhodopsin and a related protein Tmem231, and the ciliary localization of the latter was also altered in the mutant photoreceptors. Taken together, these results suggest a crucial role of Tmem138 in the functional organization of the CC, which is essential for rhodopsin localization and OS biogenesis.
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16
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Chandra B, Tung ML, Hsu Y, Scheetz T, Sheffield VC. Retinal ciliopathies through the lens of Bardet-Biedl Syndrome: Past, present and future. Prog Retin Eye Res 2021; 89:101035. [PMID: 34929400 DOI: 10.1016/j.preteyeres.2021.101035] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 12/15/2022]
Abstract
The primary cilium is a highly specialized and evolutionary conserved organelle in eukaryotes that plays a significant role in cell signaling and trafficking. Over the past few decades tremendous progress has been made in understanding the physiology of cilia and the underlying pathomechanisms of various ciliopathies. Syndromic ciliopathies consist of a group of disorders caused by ciliary dysfunction or abnormal ciliogenesis. These disorders have multiorgan involvement in addition to retinal degeneration underscoring the ubiquitous distribution of primary cilia in different cell types. Genotype-phenotype correlation is often challenging due to the allelic heterogeneity and pleiotropy of these disorders. In this review, we discuss the clinical and genetic features of syndromic ciliopathies with a focus on Bardet-Biedl syndrome (BBS) as a representative disorder. We discuss the structure and function of primary cilia and their role in retinal photoreceptors. We describe the progress made thus far in understanding the functional and genetic characterization including expression quantitative trait locus (eQTL) analysis of BBS genes. In the future directions section, we discuss the emerging technologies, such as gene therapy, as well as anticipated challenges and their implications in therapeutic development for ciliopathies.
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Affiliation(s)
- Bharatendu Chandra
- Stead Family Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Moon Ley Tung
- Stead Family Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Ying Hsu
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, Iowa City, IA, USA
| | - Todd Scheetz
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, Iowa City, IA, USA
| | - Val C Sheffield
- Stead Family Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, Iowa City, IA, USA.
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17
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Dahl TM, Reed M, Gerstner CD, Baehr W. Conditional Deletion of Cytoplasmic Dynein Heavy Chain in Postnatal Photoreceptors. Invest Ophthalmol Vis Sci 2021; 62:23. [PMID: 34807236 PMCID: PMC8626856 DOI: 10.1167/iovs.62.14.23] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Purpose Cytoplasmic dynein-1 (henceforth dynein) moves cargo in conjunction with dynactin toward the minus end of microtubules. The dynein heavy chain, DYNC1H1, comprises the backbone of dynein, a retrograde motor. Deletion of Dync1h1 abrogates dynein function. The purpose of this communication is to demonstrate effects of photoreceptor dynein inactivation during late postnatal development and in adult retina. Methods We mated Dync1h1F/F mice with iCre75 and Prom1-CreERT2 mice to generate conditional rod and tamoxifen-induced knockout in rods and cones, respectively. We documented retina degeneration with confocal microscopy at postnatal day (P) 10 to P30 for the iCre75 line and 1 to 4 weeks post tamoxifen induction (wPTI) for the Prom1-CreERT2 line. We performed scotopic and photopic electroretinography (ERG) at P16 to P30 in the iCre75 line and at 1-week increments in the Prom1-CreERT2 line. Results were evaluated statistically using Student's t-test, two-factor ANOVA, and Welch's ANOVA. Results Cre-induced homologous recombination of Dync1h1F/F mice truncated DYNC1H1 after exon 23. rodDync1h1-/- photoreceptors degenerated after P14, reducing outer nuclear layer (ONL) thickness and combined inner segment/outer segment (IS/OS) length significantly by P18. Scotopic ERG a-wave amplitudes decreased by P16 and were extinguished at P30. Cones were stable under rod-knockout conditions until P21 but inactive at P30. In tamDync1h1-/- photoreceptors, the IS/OS began shortening by 3wPTI and were nearly eliminated by 4wPTI. The ONL shrank significantly over this interval, indicating rapid photoreceptor degeneration following the loss of dynein. Conclusions Our results demonstrate dynein is essential for the secretory pathway, formation of outer segments, and photoreceptor maintenance.
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Affiliation(s)
- Tiffanie M Dahl
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah, United States
| | - Michelle Reed
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah, United States
| | - Cecilia D Gerstner
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah, United States
| | - Wolfgang Baehr
- Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah, United States.,Department of Neurobiology & Anatomy, University of Utah, Salt Lake City, Utah, United States.,Department of Biology, University of Utah, Salt Lake City, Utah, United States
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18
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Ebke LA, Sinha S, Pauer GJT, Hagstrom SA. Photoreceptor Compartment-Specific TULP1 Interactomes. Int J Mol Sci 2021; 22:ijms22158066. [PMID: 34360830 PMCID: PMC8348715 DOI: 10.3390/ijms22158066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/06/2021] [Accepted: 07/12/2021] [Indexed: 12/16/2022] Open
Abstract
Photoreceptors are highly compartmentalized cells with large amounts of proteins synthesized in the inner segment (IS) and transported to the outer segment (OS) and synaptic terminal. Tulp1 is a photoreceptor-specific protein localized to the IS and synapse. In the absence of Tulp1, several OS-specific proteins are mislocalized and synaptic vesicle recycling is impaired. To better understand the involvement of Tulp1 in protein trafficking, our approach in the current study was to physically isolate Tulp1-containing photoreceptor compartments by serial tangential sectioning of retinas and to identify compartment-specific Tulp1 binding partners by immunoprecipitation followed by liquid chromatography tandem mass spectrometry. Our results indicate that Tulp1 has two distinct interactomes. We report the identification of: (1) an IS-specific interaction between Tulp1 and the motor protein Kinesin family member 3a (Kif3a), (2) a synaptic-specific interaction between Tulp1 and the scaffold protein Ribeye, and (3) an interaction between Tulp1 and the cytoskeletal protein microtubule-associated protein 1B (MAP1B) in both compartments. Immunolocalization studies in the wild-type retina indicate that Tulp1 and its binding partners co-localize to their respective compartments. Our observations are compatible with Tulp1 functioning in protein trafficking in multiple photoreceptor compartments, likely as an adapter molecule linking vesicles to molecular motors and the cytoskeletal scaffold.
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Affiliation(s)
- Lindsey A. Ebke
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (L.A.E.); (S.S.); (G.J.T.P.)
| | - Satyabrata Sinha
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (L.A.E.); (S.S.); (G.J.T.P.)
| | - Gayle J. T. Pauer
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (L.A.E.); (S.S.); (G.J.T.P.)
| | - Stephanie A. Hagstrom
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (L.A.E.); (S.S.); (G.J.T.P.)
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA
- Correspondence:
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Wensel TG, Potter VL, Moye A, Zhang Z, Robichaux MA. Structure and dynamics of photoreceptor sensory cilia. Pflugers Arch 2021; 473:1517-1537. [PMID: 34050409 DOI: 10.1007/s00424-021-02564-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 04/07/2021] [Accepted: 04/08/2021] [Indexed: 02/06/2023]
Abstract
The rod and cone photoreceptor cells of the vertebrate retina have highly specialized structures that enable them to carry out their function of light detection over a broad range of illumination intensities with optimized spatial and temporal resolution. Most prominent are their unusually large sensory cilia, consisting of outer segments packed with photosensitive disc membranes, a connecting cilium with many features reminiscent of the primary cilium transition zone, and a pair of centrioles forming a basal body which serves as the platform upon which the ciliary axoneme is assembled. These structures form a highway through which an enormous flux of material moves on a daily basis to sustain the continual turnover of outer segment discs and the energetic demands of phototransduction. After decades of study, the details of the fine structure and distribution of molecular components of these structures are still incompletely understood, but recent advances in cellular imaging techniques and animal models of inherited ciliary defects are yielding important new insights. This knowledge informs our understanding both of the mechanisms of trafficking and assembly and of the pathophysiological mechanisms of human blinding ciliopathies.
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Affiliation(s)
- Theodore G Wensel
- Vera and Marrs McLean Department of Biochemistry and Molecular Biology and Developmental Biology Graduate Program, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Valencia L Potter
- Vera and Marrs McLean Department of Biochemistry and Molecular Biology and Developmental Biology Graduate Program, Baylor College of Medicine, Houston, TX, 77030, USA
- Medical Scientist Training Program (MSTP), Baylor College of Medicine, Houston, TX, 77030, USA
| | - Abigail Moye
- Vera and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Zhixian Zhang
- Vera and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Michael A Robichaux
- Departments of Ophthalmology and Biochemistry, West Virginia University, Morgantown, WV, USA
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20
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ADIPOR1 deficiency-induced suppression of retinal ELOVL2 and docosahexaenoic acid levels during photoreceptor degeneration and visual loss. Cell Death Dis 2021; 12:458. [PMID: 33963174 PMCID: PMC8105316 DOI: 10.1038/s41419-021-03741-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 03/23/2021] [Accepted: 03/25/2021] [Indexed: 02/03/2023]
Abstract
Lipid metabolism-related gene mutations can cause retinitis pigmentosa, a currently untreatable blinding disease resulting from progressive neurodegeneration of the retina. Here, we demonstrated the influence of adiponectin receptor 1 (ADIPOR1) deficiency in retinal neurodegeneration using Adipor1 knockout (KO) mice. Adipor1 mRNA was observed to be expressed in photoreceptors, predominately within the photoreceptor inner segment (PIS), and increased after birth during the development of the photoreceptor outer segments (POSs) where photons are received by the visual pigment, rhodopsin. At 3 weeks of age, visual function impairment, specifically photoreceptor dysfunction, as recorded by electroretinography (ERG), was evident in homozygous, but not heterozygous, Adipor1 KO mice. However, although photoreceptor loss was evident at 3 weeks of age and progressed until 10 weeks, the level of visual dysfunction was already substantial by 3 weeks, after which it was retained until 10 weeks of age. The rhodopsin mRNA levels had already decreased at 3 weeks, suggesting that reduced rhodopsin may have contributed to early visual loss. Moreover, inflammation and oxidative stress were induced in homozygous KO retinas. Prior to observation of photoreceptor loss via optical microscopy, electron microscopy revealed that POSs were present; however, they were misaligned and their lipid composition, including docosahexaenoic acid (DHA), which is critical in forming POSs, was impaired in the retina. Importantly, the expression of Elovl2, an elongase of very long chain fatty acids expressed in the PIS, was significantly reduced, and lipogenic genes, which are induced under conditions of reduced endogenous DHA synthesis, were increased in homozygous KO mice. The causal relationship between ADIPOR1 deficiency and Elovl2 repression, together with upregulation of lipogenic genes, was confirmed in vitro. Therefore, ADIPOR1 in the retina appears to be indispensable for ELOVL2 induction, which is likely required to supply sufficient DHA for appropriate photoreceptor function and survival.
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21
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Datta P, Cribbs JT, Seo S. Differential requirement of NPHP1 for compartmentalized protein localization during photoreceptor outer segment development and maintenance. PLoS One 2021; 16:e0246358. [PMID: 33961633 PMCID: PMC8104407 DOI: 10.1371/journal.pone.0246358] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 04/20/2021] [Indexed: 12/16/2022] Open
Abstract
Nephrocystin (NPHP1) is a ciliary transition zone protein and its ablation causes nephronophthisis (NPHP) with partially penetrant retinal dystrophy. However, the precise requirements of NPHP1 in photoreceptors are not well understood. Here, we characterize retinal degeneration in a mouse model of NPHP1 and show that NPHP1 is required to prevent infiltration of inner segment plasma membrane proteins into the outer segment during the photoreceptor maturation. We demonstrate that Nphp1 gene-trap mutant mice, which were previously described as null, are likely hypomorphs due to the production of a small quantity of functional mRNAs derived from nonsense-associated altered splicing and skipping of two exons including the one harboring the gene-trap. In homozygous mutant animals, inner segment plasma membrane proteins such as syntaxin-3 (STX3), synaptosomal-associated protein 25 (SNAP25), and interphotoreceptor matrix proteoglycan 2 (IMPG2) accumulate in the outer segment when outer segments are actively elongating. This phenotype, however, is spontaneously ameliorated after the outer segment elongation is completed. Consistent with this, some photoreceptor cell loss (~30%) occurs during the photoreceptor maturation period but it stops afterward. We further show that Nphp1 genetically interacts with Cep290, another NPHP gene, and that a reduction of Cep290 gene dose results in retinal degeneration that continues until adulthood in Nphp1 mutant mice. These findings demonstrate that NPHP1 is required for the confinement of inner segment plasma membrane proteins during the outer segment development, but its requirement diminishes as photoreceptors mature. Our study also suggests that additional mutations in other NPHP genes may influence the penetrance of retinopathy in human NPHP1 patients.
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Affiliation(s)
- Poppy Datta
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Institute for Vision Research, The University of Iowa, Iowa City, IA, United States of America
| | - J. Thomas Cribbs
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Institute for Vision Research, The University of Iowa, Iowa City, IA, United States of America
| | - Seongjin Seo
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Institute for Vision Research, The University of Iowa, Iowa City, IA, United States of America
- * E-mail:
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22
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Cideciyan AV, Jacobson SG, Ho AC, Garafalo AV, Roman AJ, Sumaroka A, Krishnan AK, Swider M, Schwartz MR, Girach A. Durable vision improvement after a single treatment with antisense oligonucleotide sepofarsen: a case report. Nat Med 2021; 27:785-789. [PMID: 33795869 PMCID: PMC8127404 DOI: 10.1038/s41591-021-01297-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 03/01/2021] [Indexed: 12/21/2022]
Abstract
Leber congenital amaurosis due to CEP290 ciliopathy is being explored by treatment with the antisense oligonucleotide (AON) sepofarsen. One patient who was part of a larger cohort (ClinicalTrials.gov NCT03140969 ) was studied for 15 months after a single intravitreal sepofarsen injection. Concordant measures of visual function and retinal structure reached a substantial efficacy peak near 3 months after injection. At 15 months, there was sustained efficacy, even though there was evidence of reduction from peak response. Efficacy kinetics can be explained by the balance of AON-driven new CEP290 protein synthesis and a slow natural rate of CEP290 protein degradation in human foveal cone photoreceptors.
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Affiliation(s)
- Artur V Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Samuel G Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Allen C Ho
- Wills Eye Hospital, Thomas Jefferson University, Philadelphia PA, USA
| | - Alexandra V Garafalo
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alejandro J Roman
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander Sumaroka
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Arun K Krishnan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Malgorzata Swider
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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23
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Skiba NP, Cady MA, Molday L, Han JYS, Lewis TR, Spencer WJ, Thompson WJ, Hiles S, Philp NJ, Molday RS, Arshavsky VY. TMEM67, TMEM237, and Embigin in Complex With Monocarboxylate Transporter MCT1 Are Unique Components of the Photoreceptor Outer Segment Plasma Membrane. Mol Cell Proteomics 2021; 20:100088. [PMID: 33933680 PMCID: PMC8167285 DOI: 10.1016/j.mcpro.2021.100088] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 03/25/2021] [Accepted: 04/26/2021] [Indexed: 01/18/2023] Open
Abstract
The outer segment (OS) organelle of vertebrate photoreceptors is a highly specialized cilium evolved to capture light and initiate light response. The plasma membrane which envelopes the OS plays vital and diverse roles in supporting photoreceptor function and health. However, little is known about the identity of its protein constituents, as this membrane cannot be purified to homogeneity. In this study, we used the technique of protein correlation profiling to identify unique OS plasma membrane proteins. To achieve this, we used label-free quantitative MS to compare relative protein abundances in an enriched preparation of the OS plasma membrane with a preparation of total OS membranes. We have found that only five proteins were enriched at the same level as previously validated OS plasma membrane markers. Two of these proteins, TMEM67 and TMEM237, had not been previously assigned to this membrane, and one, embigin, had not been identified in photoreceptors. We further showed that embigin associates with monocarboxylate transporter MCT1 in the OS plasma membrane, facilitating lactate transport through this cellular compartment.
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Affiliation(s)
- Nikolai P Skiba
- Albert Eye Research Institute, Duke University Medical Center, Durham, North Carolina, USA.
| | - Martha A Cady
- Albert Eye Research Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - Laurie Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - John Y S Han
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Tylor R Lewis
- Albert Eye Research Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - William J Spencer
- Albert Eye Research Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - Will J Thompson
- Duke Proteomics and Metabolomics Shared Resource, Duke University, Durham, North Carolina, USA
| | - Sarah Hiles
- Duke Proteomics and Metabolomics Shared Resource, Duke University, Durham, North Carolina, USA
| | - Nancy J Philp
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Vadim Y Arshavsky
- Albert Eye Research Institute, Duke University Medical Center, Durham, North Carolina, USA.
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24
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Das Y, Swinkels D, Baes M. Peroxisomal Disorders and Their Mouse Models Point to Essential Roles of Peroxisomes for Retinal Integrity. Int J Mol Sci 2021; 22:ijms22084101. [PMID: 33921065 PMCID: PMC8071455 DOI: 10.3390/ijms22084101] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 12/31/2022] Open
Abstract
Peroxisomes are multifunctional organelles, well known for their role in cellular lipid homeostasis. Their importance is highlighted by the life-threatening diseases caused by peroxisomal dysfunction. Importantly, most patients suffering from peroxisomal biogenesis disorders, even those with a milder disease course, present with a number of ocular symptoms, including retinopathy. Patients with a selective defect in either peroxisomal α- or β-oxidation or ether lipid synthesis also suffer from vision problems. In this review, we thoroughly discuss the ophthalmological pathology in peroxisomal disorder patients and, where possible, the corresponding animal models, with a special emphasis on the retina. In addition, we attempt to link the observed retinal phenotype to the underlying biochemical alterations. It appears that the retinal pathology is highly variable and the lack of histopathological descriptions in patients hampers the translation of the findings in the mouse models. Furthermore, it becomes clear that there are still large gaps in the current knowledge on the contribution of the different metabolic disturbances to the retinopathy, but branched chain fatty acid accumulation and impaired retinal PUFA homeostasis are likely important factors.
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25
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Ran J, Zhou J. Targeting the photoreceptor cilium for the treatment of retinal diseases. Acta Pharmacol Sin 2020; 41:1410-1415. [PMID: 32753732 DOI: 10.1038/s41401-020-0486-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/28/2020] [Indexed: 02/08/2023] Open
Abstract
Photoreceptors, as polarised sensory neurons, are essential for light sensation and phototransduction, which are highly dependent on the photoreceptor cilium. Structural defects and/or dysfunction of the photoreceptor cilium caused by mutations in photoreceptor-specific genes or common ciliary genes can lead to retinal diseases, including syndromic and nonsyndromic diseases. In this review, we describe the structure and function of the photoreceptor cilium. We also discuss recent findings that underscore the dysregulation of the photoreceptor cilium in various retinal diseases and the therapeutic potential of targeting ciliary genes in these diseases.
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26
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Karlen SJ, Miller EB, Burns ME. Microglia Activation and Inflammation During the Death of Mammalian Photoreceptors. Annu Rev Vis Sci 2020; 6:149-169. [PMID: 32936734 PMCID: PMC10135402 DOI: 10.1146/annurev-vision-121219-081730] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Photoreceptors are highly specialized sensory neurons with unique metabolic and physiological requirements. These requirements are partially met by Müller glia and cells of the retinal pigment epithelium (RPE), which provide essential metabolites, phagocytose waste, and control the composition of the surrounding microenvironment. A third vital supporting cell type, the retinal microglia, can provide photoreceptors with neurotrophic support or exacerbate neuroinflammation and hasten neuronal cell death. Understanding the physiological requirements for photoreceptor homeostasis and the factors that drive microglia to best promote photoreceptor survival has important implications for the treatment and prevention of blinding degenerative diseases like retinitis pigmentosa and age-related macular degeneration.
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Affiliation(s)
- Sarah J. Karlen
- Department of Cell Biology and Human Anatomy, University of California, Davis, Davis, California 95616, USA
| | - Eric B. Miller
- Center for Neuroscience, University of California, Davis, Davis, California 95616, USA
| | - Marie E. Burns
- Department of Cell Biology and Human Anatomy, University of California, Davis, Davis, California 95616, USA
- Center for Neuroscience, University of California, Davis, Davis, California 95616, USA
- Department of Ophthalmology & Vision Science, University of California, Davis, Davis, California 95616, USA
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27
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Chen HY, Kelley RA, Li T, Swaroop A. Primary cilia biogenesis and associated retinal ciliopathies. Semin Cell Dev Biol 2020; 110:70-88. [PMID: 32747192 PMCID: PMC7855621 DOI: 10.1016/j.semcdb.2020.07.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/14/2020] [Accepted: 07/18/2020] [Indexed: 12/19/2022]
Abstract
The primary cilium is a ubiquitous microtubule-based organelle that senses external environment and modulates diverse signaling pathways in different cell types and tissues. The cilium originates from the mother centriole through a complex set of cellular events requiring hundreds of distinct components. Aberrant ciliogenesis or ciliary transport leads to a broad spectrum of clinical entities with overlapping yet highly variable phenotypes, collectively called ciliopathies, which include sensory defects and syndromic disorders with multi-organ pathologies. For efficient light detection, photoreceptors in the retina elaborate a modified cilium known as the outer segment, which is packed with membranous discs enriched for components of the phototransduction machinery. Retinopathy phenotype involves dysfunction and/or degeneration of the light sensing photoreceptors and is highly penetrant in ciliopathies. This review will discuss primary cilia biogenesis and ciliopathies, with a focus on the retina, and the role of CP110-CEP290-CC2D2A network. We will also explore how recent technologies can advance our understanding of cilia biology and discuss new paradigms for developing potential therapies of retinal ciliopathies.
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Affiliation(s)
- Holly Y Chen
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, MSC0610, 6 Center Drive, Bethesda, MD 20892, USA.
| | - Ryan A Kelley
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, MSC0610, 6 Center Drive, Bethesda, MD 20892, USA
| | - Tiansen Li
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, MSC0610, 6 Center Drive, Bethesda, MD 20892, USA
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, MSC0610, 6 Center Drive, Bethesda, MD 20892, USA.
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28
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Finkelstein S, Gospe SM, Schuhmann K, Shevchenko A, Arshavsky VY, Lobanova ES. Phosphoinositide Profile of the Mouse Retina. Cells 2020; 9:cells9061417. [PMID: 32517352 PMCID: PMC7349851 DOI: 10.3390/cells9061417] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/18/2020] [Accepted: 06/04/2020] [Indexed: 12/24/2022] Open
Abstract
Phosphoinositides are known to play multiple roles in eukaryotic cells. Although dysregulation of phosphoinositide metabolism in the retina has been reported to cause visual dysfunction in animal models and human patients, our understanding of the phosphoinositide composition of the retina is limited. Here, we report a characterization of the phosphoinositide profile of the mouse retina and an analysis of the subcellular localization of major phosphorylated phosphoinositide forms in light-sensitive photoreceptor neurons. Using chromatography of deacylated phosphatidylinositol headgroups, we established PI(4,5)P2 and PI(4)P as two major phosphorylated phosphoinositides in the retina. Using high-resolution mass spectrometry, we revealed 18:0/20:4 and 16:0/20:4 as major fatty-acyl chains of retinal phosphoinositides. Finally, analysis of fluorescent phosphoinositide sensors in rod photoreceptors demonstrated distinct subcellular distribution patterns of major phosphoinositides. The PI(4,5)P2 reporter was enriched in the inner segments and synapses, but was barely detected in the light-sensitive outer segments. The PI(4)P reporter was mostly found in the outer and inner segments and the areas around nuclei, but to a lesser degree in the synaptic region. These findings provide support for future mechanistic studies defining the biological significance of major mono- (PI(4)P) and bisphosphate (PI(4,5)P2) phosphatidylinositols in photoreceptor biology and retinal health.
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Affiliation(s)
- Stella Finkelstein
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA; (S.F.); (S.M.G.III); (V.Y.A.)
| | - Sidney M. Gospe
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA; (S.F.); (S.M.G.III); (V.Y.A.)
| | - Kai Schuhmann
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany; (K.S.); (A.S.)
| | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany; (K.S.); (A.S.)
| | - Vadim Y. Arshavsky
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA; (S.F.); (S.M.G.III); (V.Y.A.)
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710, USA
| | - Ekaterina S. Lobanova
- Department of Ophthalmology, University of Florida, Gainesville, FL 32610, USA
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA
- Correspondence:
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29
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Collin GB, Gogna N, Chang B, Damkham N, Pinkney J, Hyde LF, Stone L, Naggert JK, Nishina PM, Krebs MP. Mouse Models of Inherited Retinal Degeneration with Photoreceptor Cell Loss. Cells 2020; 9:cells9040931. [PMID: 32290105 PMCID: PMC7227028 DOI: 10.3390/cells9040931] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/05/2020] [Accepted: 04/07/2020] [Indexed: 12/12/2022] Open
Abstract
Inherited retinal degeneration (RD) leads to the impairment or loss of vision in millions of individuals worldwide, most frequently due to the loss of photoreceptor (PR) cells. Animal models, particularly the laboratory mouse, have been used to understand the pathogenic mechanisms that underlie PR cell loss and to explore therapies that may prevent, delay, or reverse RD. Here, we reviewed entries in the Mouse Genome Informatics and PubMed databases to compile a comprehensive list of monogenic mouse models in which PR cell loss is demonstrated. The progression of PR cell loss with postnatal age was documented in mutant alleles of genes grouped by biological function. As anticipated, a wide range in the onset and rate of cell loss was observed among the reported models. The analysis underscored relationships between RD genes and ciliary function, transcription-coupled DNA damage repair, and cellular chloride homeostasis. Comparing the mouse gene list to human RD genes identified in the RetNet database revealed that mouse models are available for 40% of the known human diseases, suggesting opportunities for future research. This work may provide insight into the molecular players and pathways through which PR degenerative disease occurs and may be useful for planning translational studies.
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Affiliation(s)
- Gayle B. Collin
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Navdeep Gogna
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Nattaya Damkham
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
- Siriraj Center of Excellence for Stem Cell Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Jai Pinkney
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Lillian F. Hyde
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Lisa Stone
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Jürgen K. Naggert
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Patsy M. Nishina
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
- Correspondence: (P.M.N.); (M.P.K.); Tel.: +1-207-2886-383 (P.M.N.); +1-207-2886-000 (M.P.K.)
| | - Mark P. Krebs
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
- Correspondence: (P.M.N.); (M.P.K.); Tel.: +1-207-2886-383 (P.M.N.); +1-207-2886-000 (M.P.K.)
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30
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Datta P, Hendrickson B, Brendalen S, Ruffcorn A, Seo S. The myosin-tail homology domain of centrosomal protein 290 is essential for protein confinement between the inner and outer segments in photoreceptors. J Biol Chem 2019; 294:19119-19136. [PMID: 31694913 DOI: 10.1074/jbc.ra119.009712] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 10/30/2019] [Indexed: 12/13/2022] Open
Abstract
Mutations in the centrosomal protein 290 (CEP290) gene cause various ciliopathies involving retinal degeneration. CEP290 proteins localize to the ciliary transition zone and are thought to act as a gatekeeper that controls ciliary protein trafficking. However, precise roles of CEP290 in photoreceptors and pathomechanisms of retinal degeneration in CEP290-associated ciliopathies are not sufficiently understood. Using conditional Cep290 mutant mice, in which the C-terminal myosin-tail homology domain of CEP290 is disrupted after the connecting cilium is assembled, we show that this domain is essential for protein confinement between the inner and the outer segments. Upon disruption of the myosin-tail homology domain, inner segment plasma membrane proteins, including syntaxin 3 (STX3), synaptosome-associated protein 25 (SNAP25), and interphotoreceptor matrix proteoglycan 2 (IMPG2), rapidly accumulated in the outer segment. In contrast, localization of endomembrane proteins was not altered. Trafficking and confinement of most outer segment-resident proteins appeared to be unaffected or only minimally affected in Cep290 mutant mice. One notable exception was rhodopsin (RHO), which severely mislocalized to inner segments during the initial stage of degeneration. Similar mislocalization phenotypes were observed in Cep290rd16 mice. These results suggest that a failure of protein confinement at the connecting cilium and consequent accumulation of inner segment membrane proteins in the outer segment, along with insufficient RHO delivery, is part of the disease mechanisms that cause retinal degeneration in CEP290-associated ciliopathies. Our study provides insights into the pathomechanisms of retinal degenerations associated with compromised ciliary gates.
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Affiliation(s)
- Poppy Datta
- Department of Ophthalmology and Visual Sciences, University of Iowa College of Medicine, Iowa City, Iowa 52242.,Institute for Vision Research, University of Iowa, Iowa City, Iowa 52242
| | - Brandon Hendrickson
- Department of Ophthalmology and Visual Sciences, University of Iowa College of Medicine, Iowa City, Iowa 52242.,Institute for Vision Research, University of Iowa, Iowa City, Iowa 52242
| | - Sarah Brendalen
- Department of Ophthalmology and Visual Sciences, University of Iowa College of Medicine, Iowa City, Iowa 52242.,Institute for Vision Research, University of Iowa, Iowa City, Iowa 52242
| | - Avri Ruffcorn
- Department of Ophthalmology and Visual Sciences, University of Iowa College of Medicine, Iowa City, Iowa 52242.,Institute for Vision Research, University of Iowa, Iowa City, Iowa 52242
| | - Seongjin Seo
- Department of Ophthalmology and Visual Sciences, University of Iowa College of Medicine, Iowa City, Iowa 52242 .,Institute for Vision Research, University of Iowa, Iowa City, Iowa 52242
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