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Fan Z, Hu Y, Chen L, Lu X, Zheng L, Ma D, Li Z, Zhong J, Lin L, Zhang S, Zhang G. Multiplatform tear proteomic profiling reveals novel non-invasive biomarkers for diabetic retinopathy. Eye (Lond) 2024; 38:1509-1517. [PMID: 38336992 PMCID: PMC11126564 DOI: 10.1038/s41433-024-02938-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 12/19/2023] [Accepted: 01/16/2024] [Indexed: 02/12/2024] Open
Abstract
OBJECTIVES To investigate a comprehensive proteomic profile of the tear fluid in patients with diabetic retinopathy (DR) and further define non-invasive biomarkers. METHODS A cross-sectional, multicentre study that includes 46 patients with DR, 28 patients with diabetes mellitus (DM), and 30 healthy controls (HC). Tear samples were collected with Schirmer strips. As for the discovery set, data-independent acquisition mass spectrometry was used to characterize the tear proteomic profile. Differentially expressed proteins between groups were identified, with gene ontology enrichment analysis and Kyoto Encyclopedia of Genes and Genomes enrichment analysis further developed. Classifying performance of biomarkers for distinguishing DR from DM was compared by the combination of three machine-learning algorithms. The selected biomarker panel was tested in the validation cohort using parallel reaction monitoring mass spectrometry. RESULTS Among 3364 proteins quantified, 235 and 88 differentially expressed proteins were identified for DR when compared to HC and DM, respectively, which were fundamentally related to retina homeostasis, inflammation and immunity, oxidative stress, angiogenesis and coagulation, metabolism, and cellular adhesion processes. The biomarker panel consisting of NAD-dependent protein deacetylase sirtuin-2 (SIR2), amine oxidase [flavin-containing] B (AOFB), and U8 snoRNA-decapping enzyme (NUD16) exhibited the best diagnostic performance in discriminating DR from DM, with AUCs of 0.933 and 0.881 in the discovery and validation set, respectively. CONCLUSIONS Tear protein dysregulation is comprehensively revealed to be associated with DR onset. The combination of tear SIR2, AOFB, and NUD16 can be a novel potential approach for non-invasive detection or pre-screening of DR. CLINICAL TRIAL REGISTRATION Chinese Clinical Trial Registry Identifier: ChiCTR2100054263. https://www.chictr.org.cn/showproj.html?proj=143177 . Date of registration: 2021/12/12.
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Affiliation(s)
- Zixin Fan
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, Guangdong, 518040, China
- International Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong, 518040, China
| | - Yarou Hu
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, Guangdong, 518040, China
| | - Laijiao Chen
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, Guangdong, 518040, China
| | - Xiaofeng Lu
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, Guangdong, 518040, China
| | - Lei Zheng
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, Guangdong, 518040, China
| | - Dahui Ma
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, Guangdong, 518040, China
| | - Zhiqiang Li
- Shenmei Eye Hospital, Meizhou, Guangdong, 514000, China
| | - Jingwen Zhong
- Shenmei Eye Hospital, Meizhou, Guangdong, 514000, China
| | - Lin Lin
- Southern University of Science and Technology, Shenzhen, Guangdong, 518040, China
| | - Sifan Zhang
- New York University, New York, NY 10003, USA
| | - Guoming Zhang
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, Guangdong, 518040, China.
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Kerschensteiner D. Losing, preserving, and restoring vision from neurodegeneration in the eye. Curr Biol 2023; 33:R1019-R1036. [PMID: 37816323 PMCID: PMC10575673 DOI: 10.1016/j.cub.2023.08.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
The retina is a part of the brain that sits at the back of the eye, looking out onto the world. The first neurons of the retina are the rod and cone photoreceptors, which convert changes in photon flux into electrical signals that are the basis of vision. Rods and cones are frequent targets of heritable neurodegenerative diseases that cause visual impairment, including blindness, in millions of people worldwide. This review summarizes the diverse genetic causes of inherited retinal degenerations (IRDs) and their convergence onto common pathogenic mechanisms of vision loss. Currently, there are few effective treatments for IRDs, but recent advances in disparate areas of biology and technology (e.g., genome editing, viral engineering, 3D organoids, optogenetics, semiconductor arrays) discussed here enable promising efforts to preserve and restore vision in IRD patients with implications for neurodegeneration in less approachable brain areas.
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Affiliation(s)
- Daniel Kerschensteiner
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110, USA.
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3
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Becherucci V, Bacci GM, Marziali E, Sodi A, Bambi F, Caputo R. The New Era of Therapeutic Strategies for the Treatment of Retinitis Pigmentosa: A Narrative Review of Pathomolecular Mechanisms for the Development of Cell-Based Therapies. Biomedicines 2023; 11:2656. [PMID: 37893030 PMCID: PMC10604477 DOI: 10.3390/biomedicines11102656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/20/2023] [Accepted: 09/25/2023] [Indexed: 10/29/2023] Open
Abstract
Retinitis pigmentosa, defined more properly as cone-rod dystrophy, is a paradigm of inherited diffuse retinal dystrophies, one of the rare diseases with the highest prevalence in the worldwide population and one of the main causes of low vision in the pediatric and elderly age groups. Advancements in and the understanding of molecular biology and gene-editing technologies have raised interest in laying the foundation for new therapeutic strategies for rare diseases. As a consequence, new possibilities for clinicians and patients are arising due to the feasibility of treating such a devastating disorder, reducing its complications. The scope of this review focuses on the pathomolecular mechanisms underlying RP better to understand the prospects of its treatment using innovative approaches.
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Affiliation(s)
- Valentina Becherucci
- Cell Factory Meyer, Children’s Hospital A. Meyer Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS), University of Florence, 50139 Florence, Italy; (V.B.); (F.B.)
| | - Giacomo Maria Bacci
- Pediatric Ophthalmology Unit, Children’s Hospital A. Meyer Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS), University of Florence, 50139 Florence, Italy; (E.M.); (R.C.)
| | - Elisa Marziali
- Pediatric Ophthalmology Unit, Children’s Hospital A. Meyer Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS), University of Florence, 50139 Florence, Italy; (E.M.); (R.C.)
| | - Andrea Sodi
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, 50139 Florence, Italy;
| | - Franco Bambi
- Cell Factory Meyer, Children’s Hospital A. Meyer Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS), University of Florence, 50139 Florence, Italy; (V.B.); (F.B.)
| | - Roberto Caputo
- Pediatric Ophthalmology Unit, Children’s Hospital A. Meyer Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS), University of Florence, 50139 Florence, Italy; (E.M.); (R.C.)
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4
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Han X, Zhang L, Kong L, Tong M, Shi Z, Li XM, Zhang T, Jiang Q, Biao Y. Comprehensive metabolic profiling of diabetic retinopathy. Exp Eye Res 2023; 233:109538. [PMID: 37308049 DOI: 10.1016/j.exer.2023.109538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 06/01/2023] [Accepted: 06/09/2023] [Indexed: 06/14/2023]
Abstract
Diabetic retinopathy (DR) is an important complication of diabetes mellitus and a prevalent blind-causing ophthalmic disease. Despite years of efforts, rapid and accurate diagnosis of DR remains a challenging task. Metabolomics has been used as a diagnostic tool for disease progression and therapy monitoring. In this study, retinal tissues were collected from diabetic mice and age-matched non-diabetic mice. An unbiased metabolic profiling was performed to identify the altered metabolites and metabolic pathways in DR. 311 differential metabolites were identified between diabetic retinas and non-diabetic retinas under the criteria of variable importance in projection (VIP) > 1 and P < 0.05. These differential metabolites were highly enriched in purine metabolism, amino acid metabolism, glycerophospholipid metabolism, and pantaothenate and CoA biosynthesis. We then evaluated the sensitivity and specificity of purine metabolites as the candidate biomarkers for DR through the area under the receiver-operating characteristic curves (AUC-ROCs). Compared with other purine metabolites, adenosine, guanine, and inosine had higher sensitivity, specificity, and accuracy for DR prediction. In conclusion, this study sheds new light on the metabolic mechanism of DR, which can facilitate clinical diagnosis, therapy, and prognosis of DR in the future.
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Affiliation(s)
- Xiaoyan Han
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China
| | - Lili Zhang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China
| | - Lingjie Kong
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China
| | - Ming Tong
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China
| | - Zehui Shi
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China
| | - Xiu Miao Li
- The Affiliated Eye Hospital, Nanjing Medical University, Nanjing, China; The Fourth School of Clinical Medicine, Nanjing Medical University, Nanjing, China
| | - Ting Zhang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China.
| | - Qin Jiang
- The Affiliated Eye Hospital, Nanjing Medical University, Nanjing, China; The Fourth School of Clinical Medicine, Nanjing Medical University, Nanjing, China.
| | - Yan Biao
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China.
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Pérez-Acuña D, Rhee KH, Shin SJ, Ahn J, Lee JY, Lee SJ. Retina-to-brain spreading of α-synuclein after intravitreal injection of preformed fibrils. Acta Neuropathol Commun 2023; 11:83. [PMID: 37210559 DOI: 10.1186/s40478-023-01575-0] [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: 04/25/2023] [Accepted: 04/30/2023] [Indexed: 05/22/2023] Open
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterized by the aggregation of misfolded α-synuclein and progressive spreading of the aggregates from a few discrete regions to wider brain regions. Although PD has been classically considered a movement disorder, a large body of clinical evidence has revealed the progressive occurrence of non-motor symptoms. Patients present visual symptoms in the initial stages of the disease, and accumulation of phospho-α-synuclein, dopaminergic neuronal loss, and retinal thinning has been observed in the retinas of PD patients. Based on such human data, we hypothesized that α-synuclein aggregation can initiate in the retina and spread to the brain through the visual pathway. Here, we demonstrate accumulation of α-synuclein in the retinas and brains of naive mice after intravitreal injection of α-synuclein preformed fibrils (PFFs). Histological analyses showed deposition of phospho-α-synuclein inclusions within the retina 2 months after injection, with increased oxidative stress leading to loss of retinal ganglion cells and dopaminergic dysfunction. In addition, we found accumulation of phospho-α-synuclein in cortical areas with accompanying neuroinflammation after 5 months. Collectively, our findings suggest that retinal synucleinopathy lesions initiated by intravitreal injection of α-synuclein PFFs spread to various brain regions through the visual pathway in mice.
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Affiliation(s)
- Dayana Pérez-Acuña
- Department of Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-Ro, Jongro-Gu, Seoul, 03080, Korea
| | - Ka Hyun Rhee
- Department of Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-Ro, Jongro-Gu, Seoul, 03080, Korea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Soo Jean Shin
- Department of Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-Ro, Jongro-Gu, Seoul, 03080, Korea
| | - Jeeyun Ahn
- Department of Ophthalmology, College of Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul National University, Seoul, South Korea
| | - Jee-Young Lee
- Department of Neurology, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul National University College of Medicine, Seoul, South Korea
| | - Seung-Jae Lee
- Department of Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-Ro, Jongro-Gu, Seoul, 03080, Korea.
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.
- Convergence Research Center for Dementia, Seoul National University College of Medicine, Seoul, South Korea.
- Neuramedy, Seoul, South Korea.
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Chew LA, Iannaccone A. Gene-agnostic approaches to treating inherited retinal degenerations. Front Cell Dev Biol 2023; 11:1177838. [PMID: 37123404 PMCID: PMC10133473 DOI: 10.3389/fcell.2023.1177838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/31/2023] [Indexed: 05/02/2023] Open
Abstract
Most patients with inherited retinal degenerations (IRDs) have been waiting for treatments that are "just around the corner" for decades, with only a handful of seminal breakthroughs happening in recent years. Highlighting the difficulties in the quest for curative therapeutics, Luxturna required 16 years of development before finally obtaining United States Food and Drug Administration (FDA) approval and its international equivalents. IRDs are both genetically and phenotypically heterogeneous. While this diversity offers many opportunities for gene-by-gene precision medicine-based approaches, it also poses a significant challenge. For this reason, alternative (or parallel) strategies to identify more comprehensive, across-the-board therapeutics for the genetically and phenotypically diverse IRD patient population are very appealing. Even when gene-specific approaches may be available and become approved for use, many patients may have reached a disease stage whereby these approaches may no longer be viable. Thus, alternate visual preservation or restoration therapeutic approaches are needed at these stages. In this review, we underscore several gene-agnostic approaches that are being developed as therapeutics for IRDs. From retinal supplementation to stem cell transplantation, optogenetic therapy and retinal prosthetics, these strategies would bypass at least in part the need for treating every individual gene or mutation or provide an invaluable complement to them. By considering the diverse patient population and treatment strategies suited for different stages and patterns of retinal degeneration, gene agnostic approaches are very well poised to impact favorably outcomes and prognosis for IRD patients.
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Affiliation(s)
- Lindsey A. Chew
- Duke Center for Retinal Degenerations and Ophthalmic Genetic Diseases, Department of Ophthalmology, Duke Eye Center, Duke University School of Medicine, Durham, NC, United States
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, United States
| | - Alessandro Iannaccone
- Duke Center for Retinal Degenerations and Ophthalmic Genetic Diseases, Department of Ophthalmology, Duke Eye Center, Duke University School of Medicine, Durham, NC, United States
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Oamen HP, Romero Romero N, Knuckles P, Saarikangas J, Radman‐Livaja M, Dong Y, Caudron F. A rare natural lipid induces neuroglobin expression to prevent amyloid oligomers toxicity and retinal neurodegeneration. Aging Cell 2022; 21:e13645. [PMID: 35656861 PMCID: PMC9282837 DOI: 10.1111/acel.13645] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 03/10/2022] [Accepted: 05/10/2022] [Indexed: 11/29/2022] Open
Abstract
Most neurodegenerative diseases such as Alzheimer's disease are proteinopathies linked to the toxicity of amyloid oligomers. Treatments to delay or cure these diseases are lacking. Using budding yeast, we report that the natural lipid tripentadecanoin induces expression of the nitric oxide oxidoreductase Yhb1 to prevent the formation of protein aggregates during aging and extends replicative lifespan. In mammals, tripentadecanoin induces expression of the Yhb1 orthologue, neuroglobin, to protect neurons against amyloid toxicity. Tripentadecanoin also rescues photoreceptors in a mouse model of retinal degeneration and retinal ganglion cells in a Rhesus monkey model of optic atrophy. Together, we propose that tripentadecanoin affects p-bodies to induce neuroglobin expression and offers a potential treatment for proteinopathies and retinal neurodegeneration.
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Affiliation(s)
- Henry Patrick Oamen
- School of Biological and Behavioural SciencesQueen Mary University of LondonLondonUK
| | - Nathaly Romero Romero
- School of Biological and Behavioural SciencesQueen Mary University of LondonLondonUK
| | - Philip Knuckles
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
| | - Juha Saarikangas
- Helsinki Institute of Life Science, HiLIFE, University of HelsinkiHelsinkiFinland
- Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center, University of HelsinkiHelsinkiFinland
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Pinilla I, Maneu V, Campello L, Fernández-Sánchez L, Martínez-Gil N, Kutsyr O, Sánchez-Sáez X, Sánchez-Castillo C, Lax P, Cuenca N. Inherited Retinal Dystrophies: Role of Oxidative Stress and Inflammation in Their Physiopathology and Therapeutic Implications. Antioxidants (Basel) 2022; 11:antiox11061086. [PMID: 35739983 PMCID: PMC9219848 DOI: 10.3390/antiox11061086] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 05/24/2022] [Accepted: 05/26/2022] [Indexed: 12/13/2022] Open
Abstract
Inherited retinal dystrophies (IRDs) are a large group of genetically and clinically heterogeneous diseases characterized by the progressive degeneration of the retina, ultimately leading to loss of visual function. Oxidative stress and inflammation play fundamental roles in the physiopathology of these diseases. Photoreceptor cell death induces an inflammatory state in the retina. The activation of several molecular pathways triggers different cellular responses to injury, including the activation of microglia to eliminate debris and recruit inflammatory cells from circulation. Therapeutical options for IRDs are currently limited, although a small number of patients have been successfully treated by gene therapy. Many other therapeutic strategies are being pursued to mitigate the deleterious effects of IRDs associated with oxidative metabolism and/or inflammation, including inhibiting reactive oxygen species’ accumulation and inflammatory responses, and blocking autophagy. Several compounds are being tested in clinical trials, generating great expectations for their implementation. The present review discusses the main death mechanisms that occur in IRDs and the latest therapies that are under investigation.
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Affiliation(s)
- Isabel Pinilla
- Aragón Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
- Department of Ophthalmology, Lozano Blesa, University Hospital, 50009 Zaragoza, Spain
- Department of Surgery, University of Zaragoza, 50009 Zaragoza, Spain
- Correspondence: (I.P.); (V.M.)
| | - Victoria Maneu
- Department of Optics, Pharmacology and Anatomy, University of Alicante, 03690 Alicante, Spain;
- Alicante Institute for Health and Biomedical Research (ISABIAL), 03010 Alicante, Spain; (P.L.); (N.C.)
- Correspondence: (I.P.); (V.M.)
| | - Laura Campello
- Department of Physiology, Genetics and Microbiology, University of Alicante, 03690 Alicante, Spain; (L.C.); (N.M.-G.); (O.K.); (X.S.-S.); (C.S.-C.)
| | - Laura Fernández-Sánchez
- Department of Optics, Pharmacology and Anatomy, University of Alicante, 03690 Alicante, Spain;
| | - Natalia Martínez-Gil
- Department of Physiology, Genetics and Microbiology, University of Alicante, 03690 Alicante, Spain; (L.C.); (N.M.-G.); (O.K.); (X.S.-S.); (C.S.-C.)
| | - Oksana Kutsyr
- Department of Physiology, Genetics and Microbiology, University of Alicante, 03690 Alicante, Spain; (L.C.); (N.M.-G.); (O.K.); (X.S.-S.); (C.S.-C.)
| | - Xavier Sánchez-Sáez
- Department of Physiology, Genetics and Microbiology, University of Alicante, 03690 Alicante, Spain; (L.C.); (N.M.-G.); (O.K.); (X.S.-S.); (C.S.-C.)
| | - Carla Sánchez-Castillo
- Department of Physiology, Genetics and Microbiology, University of Alicante, 03690 Alicante, Spain; (L.C.); (N.M.-G.); (O.K.); (X.S.-S.); (C.S.-C.)
| | - Pedro Lax
- Alicante Institute for Health and Biomedical Research (ISABIAL), 03010 Alicante, Spain; (P.L.); (N.C.)
- Department of Physiology, Genetics and Microbiology, University of Alicante, 03690 Alicante, Spain; (L.C.); (N.M.-G.); (O.K.); (X.S.-S.); (C.S.-C.)
| | - Nicolás Cuenca
- Alicante Institute for Health and Biomedical Research (ISABIAL), 03010 Alicante, Spain; (P.L.); (N.C.)
- Department of Physiology, Genetics and Microbiology, University of Alicante, 03690 Alicante, Spain; (L.C.); (N.M.-G.); (O.K.); (X.S.-S.); (C.S.-C.)
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Chu-Tan JA, Kirkby M, Natoli R. Running to save sight: The effects of exercise on retinal health and function. Clin Exp Ophthalmol 2021; 50:74-90. [PMID: 34741489 DOI: 10.1111/ceo.14023] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 12/29/2022]
Abstract
The benefits of exercise to human health have long been recognised. However, only in the past decade have researchers started to discover the molecular benefits that exercise confers, especially to the central nervous system (CNS). These discoveries include the magnitude of molecular messages that are communicated from skeletal muscle to the CNS. Despite these advances in understanding, very limited studies have been conducted to decipher the molecular benefits of exercise in retinal health and disease. Here, we review the latest work on the effects of exercise on the retina and discuss its effects on the wider CNS, with a focus on demonstrating the potential applicability and comparative molecular mechanisms that may be occurring in the retina. This review covers the key molecular pathways where exercise exerts its effects: oxidative stress and mitochondrial health; inflammation; protein aggregation; neuronal health; and tissue crosstalk via extracellular vesicles. Further research on the benefits of exercise to the retina and its molecular messages within extracellular vesicles is highly topical in this field.
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Affiliation(s)
- Joshua A Chu-Tan
- The John Curtin School of Medical Research, The Australian National University, Acton, Australia.,The Australian National University Medical School, The Australian National University, Acton, Australia
| | - Max Kirkby
- The John Curtin School of Medical Research, The Australian National University, Acton, Australia
| | - Riccardo Natoli
- The John Curtin School of Medical Research, The Australian National University, Acton, Australia.,The Australian National University Medical School, The Australian National University, Acton, Australia
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Abstract
Purpose Diabetic retinopathy (DR), a common microvascular complication of diabetes, is the leading cause of acquired blindness in the working-age population. Individuals with diabetes still develop DR despite appropriate glycemic and blood pressure control, highlighting the pressing need to identify useful biomarkers for risk stratification. The purpose of this review is to systematically summarize potential metabolic biomarkers and pathways of DR, which could facilitate developing an understanding of the disease mechanisms, as well as new therapeutic measures. Methods We searched PubMed and Web of Science for relevant metabolomics studies on humans published before September 30, 2020. Information regarding authors, title, publication date, study subjects, analytical platforms, methods of statistical analysis, biological samples, directions of change of potential metabolic biomarkers, and predictive values of metabolic biomarker panels was extracted, and the quality of the studies was assessed. Pathway analysis, including enrichment analysis and topology analysis, was derived from integrating differential metabolites using MetaboAnalyst 3.0, based on the Kyoto Encyclopedia of Genes and Genomes and Human Metabolome Database. Results We found nine studies focused on the identification of potential biomarkers. Repeatedly identified metabolites including l-glutamine, l-lactic acid, pyruvic acid, acetic acid, l-glutamic acid, d-glucose, l-alanine, l-threonine, citrulline, l-lysine, and succinic acid were found to be potential biomarkers of DR. It was observed that l-glutamine and citrulline changed in all biological samples. Dysregulation of metabolic pathways involved amino acid and energy metabolism. Conclusions This review summarizes potential biomarkers and metabolic pathways, providing insights into new pathogenic pathways for this microvascular complication of diabetes.
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Affiliation(s)
- Xiao-Wen Hou
- School of Public Health, Medical College of Soochow University, Suzhou, China
| | - Ying Wang
- School of Public Health, Medical College of Soochow University, Suzhou, China
| | - Chen-Wei Pan
- School of Public Health, Medical College of Soochow University, Suzhou, China
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Mullin NK, Voigt AP, Cooke JA, Bohrer LR, Burnight ER, Stone EM, Mullins RF, Tucker BA. Patient derived stem cells for discovery and validation of novel pathogenic variants in inherited retinal disease. Prog Retin Eye Res 2021; 83:100918. [PMID: 33130253 PMCID: PMC8559964 DOI: 10.1016/j.preteyeres.2020.100918] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/22/2020] [Accepted: 10/27/2020] [Indexed: 02/07/2023]
Abstract
Our understanding of inherited retinal disease has benefited immensely from molecular genetic analysis over the past several decades. New technologies that allow for increasingly detailed examination of a patient's DNA have expanded the catalog of genes and specific variants that cause retinal disease. In turn, the identification of pathogenic variants has allowed the development of gene therapies and low-cost, clinically focused genetic testing. Despite this progress, a relatively large fraction (at least 20%) of patients with clinical features suggestive of an inherited retinal disease still do not have a molecular diagnosis today. Variants that are not obviously disruptive to the codon sequence of exons can be difficult to distinguish from the background of benign human genetic variations. Some of these variants exert their pathogenic effect not by altering the primary amino acid sequence, but by modulating gene expression, isoform splicing, or other transcript-level mechanisms. While not discoverable by DNA sequencing methods alone, these variants are excellent targets for studies of the retinal transcriptome. In this review, we present an overview of the current state of pathogenic variant discovery in retinal disease and identify some of the remaining barriers. We also explore the utility of new technologies, specifically patient-derived induced pluripotent stem cell (iPSC)-based modeling, in further expanding the catalog of disease-causing variants using transcriptome-focused methods. Finally, we outline bioinformatic analysis techniques that will allow this new method of variant discovery in retinal disease. As the knowledge gleaned from previous technologies is informing targets for therapies today, we believe that integrating new technologies, such as iPSC-based modeling, into the molecular diagnosis pipeline will enable a new wave of variant discovery and expanded treatment of inherited retinal disease.
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Affiliation(s)
- Nathaniel K Mullin
- The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Andrew P Voigt
- The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Jessica A Cooke
- The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Laura R Bohrer
- The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Erin R Burnight
- The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Edwin M Stone
- The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Robert F Mullins
- The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Budd A Tucker
- The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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12
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Barabino A, Flamier A, Hanna R, Héon E, Freedman BS, Bernier G. Deregulation of Neuro-Developmental Genes and Primary Cilium Cytoskeleton Anomalies in iPSC Retinal Sheets from Human Syndromic Ciliopathies. Stem Cell Reports 2020; 14:357-373. [PMID: 32160518 PMCID: PMC7066374 DOI: 10.1016/j.stemcr.2020.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 01/22/2023] Open
Abstract
Ciliopathies are heterogeneous genetic diseases affecting primary cilium structure and function. Meckel-Gruber (MKS) and Bardet-Biedl (BBS) syndromes are severe ciliopathies characterized by skeletal and neurodevelopment anomalies, including polydactyly, cognitive impairment, and retinal degeneration. We describe the generation and molecular characterization of human induced pluripotent stem cell (iPSC)-derived retinal sheets (RSs) from controls, and MKS (TMEM67) and BBS (BBS10) cases. MKS and BBS RSs displayed significant common alterations in the expression of hundreds of developmental genes and members of the WNT and BMP pathways. Induction of crystallin molecular chaperones was prominent in MKS and BBS RSs suggesting a stress response to misfolded proteins. Unique to MKS photoreceptors was the presence of supernumerary centrioles and cilia, and aggregation of ciliary proteins. Unique to BBS photoreceptors was the accumulation of DNA damage and activation of the mitotic spindle checkpoint. This study reveals how combining cell reprogramming, organogenesis, and next-generation sequencing enables the elucidation of mechanisms involved in human ciliopathies.
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Affiliation(s)
- Andrea Barabino
- Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. Assomption, Montreal, QC H1T 2M4, Canada
| | - Anthony Flamier
- Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. Assomption, Montreal, QC H1T 2M4, Canada
| | - Roy Hanna
- Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. Assomption, Montreal, QC H1T 2M4, Canada
| | - Elise Héon
- Hospital for Sick Children, Department of Ophthalmology and Vision Sciences, Program of Genetics and Genome Biology, 555 University av., Toronto, ON M5G 1X8, Canada
| | - Benjamin S Freedman
- Department of Medicine, Division of Nephrology, Kidney Research Institute, and Institute of Stem Cell and Regenerative Medicine, and Department of Pathology, University of Washington School of Medicine, Seattle, WA 98109, USA.
| | - Gilbert Bernier
- Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. Assomption, Montreal, QC H1T 2M4, Canada; Department of Neurosciences, University of Montreal, Montreal, QC H3C 3J7, Canada; Department of Ophthalmology, University of Montreal, Montreal, QC H3C 3J7, Canada.
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13
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Chekuri A, Zientara‐Rytter K, Soto‐Hermida A, Borooah S, Voronchikhina M, Biswas P, Kumar V, Goodsell D, Hayward C, Shaw P, Stanton C, Garland D, Subramani S, Ayyagari R. Late-onset retinal degeneration pathology due to mutations in CTRP5 is mediated through HTRA1. Aging Cell 2019; 18:e13011. [PMID: 31385385 PMCID: PMC6826137 DOI: 10.1111/acel.13011] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/13/2019] [Accepted: 06/16/2019] [Indexed: 12/22/2022] Open
Abstract
Late-onset retinal degeneration (L-ORD) is an autosomal dominant macular degeneration characterized by the formation of sub-retinal pigment epithelium (RPE) deposits and neuroretinal atrophy. L-ORD results from mutations in the C1q-tumor necrosis factor-5 protein (CTRP5), encoded by the CTRP5/C1QTNF5 gene. To understand the mechanism underlying L-ORD pathology, we used a human cDNA library yeast two-hybrid screen to identify interacting partners of CTRP5. Additionally, we analyzed the Bruch's membrane/choroid (BM-Ch) from wild-type (Wt), heterozygous S163R Ctrp5 mutation knock-in (Ctrp5S163R/wt ), and homozygous knock-in (Ctrp5S163R/S163R ) mice using mass spectrometry. Both approaches showed an association between CTRP5 and HTRA1 via its C-terminal PDZ-binding motif, stimulation of the HTRA1 protease activity by CTRP5, and CTRP5 serving as an HTRA1 substrate. The S163R-CTRP5 protein also binds to HTRA1 but is resistant to HTRA1-mediated cleavage. Immunohistochemistry and proteomic analysis showed significant accumulation of CTRP5 and HTRA1 in BM-Ch of Ctrp5S163R/S163R and Ctrp5S163R/wt mice compared with Wt. Additional extracellular matrix (ECM) components that are HTRA1 substrates also accumulated in these mice. These results implicate HTRA1 and its interaction with CTRP5 in L-ORD pathology.
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Affiliation(s)
- Anil Chekuri
- Shiley Eye InstituteUniversity of California San DiegoSan DiegoCAUSA
| | | | | | - Shyamanga Borooah
- Shiley Eye InstituteUniversity of California San DiegoSan DiegoCAUSA
| | | | - Pooja Biswas
- Shiley Eye InstituteUniversity of California San DiegoSan DiegoCAUSA
| | - Virender Kumar
- Shiley Eye InstituteUniversity of California San DiegoSan DiegoCAUSA
| | - David Goodsell
- Integrative Structural and Computational Biology (ISCB)Scripps Research InstituteSan DiegoCAUSA
| | - Caroline Hayward
- Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUK
| | - Peter Shaw
- Shiley Eye InstituteUniversity of California San DiegoSan DiegoCAUSA
| | - Chloe Stanton
- Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUK
| | - Donita Garland
- Massachusetts Eye and Ear Infirmary, Department of OphthalmologyHarvard Medical SchoolBostonMAUSA
| | - Suresh Subramani
- Division of Biological SciencesUniversity of California San DiegoSan DiegoCAUSA
| | - Radha Ayyagari
- Shiley Eye InstituteUniversity of California San DiegoSan DiegoCAUSA
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14
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Li F, Hung SSC, Mohd Khalid MKN, Wang JH, Chrysostomou V, Wong VHY, Singh V, Wing K, Tu L, Bender JA, Pébay A, King AE, Cook AL, Wong RCB, Bui BV, Hewitt AW, Liu GS. Utility of Self-Destructing CRISPR/Cas Constructs for Targeted Gene Editing in the Retina. Hum Gene Ther 2019; 30:1349-1360. [PMID: 31373227 DOI: 10.1089/hum.2019.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Safe delivery of CRISPR/Cas endonucleases remains one of the major barriers to the widespread application of in vivo genome editing. We previously reported the utility of adeno-associated virus (AAV)-mediated CRISPR/Cas genome editing in the retina; however, with this type of viral delivery system, active endonucleases will remain in the retina for an extended period, making genotoxicity a significant consideration in clinical applications. To address this issue, we have designed a self-destructing "kamikaze" CRISPR/Cas system that disrupts the Cas enzyme itself following expression. Four guide RNAs (sgRNAs) were initially designed to target Streptococcus pyogenes Cas9 (SpCas9) and after in situ validation, the selected sgRNAs were cloned into a dual AAV vector. One construct was used to deliver SpCas9 and the other delivered sgRNAs directed against SpCas9 and the target locus (yellow fluorescent protein [YFP]), in the presence of mCherry. Both constructs were packaged into AAV2 vectors and intravitreally administered in C57BL/6 and Thy1-YFP transgenic mice. After 8 weeks, the expression of SpCas9 and the efficacy of YFP gene disruption were quantified. A reduction of SpCas9 mRNA was found in retinas treated with AAV2-mediated YFP/SpCas9 targeting CRISPR/Cas compared with those treated with YFP targeting CRISPR/Cas alone. We also show that AAV2-mediated delivery of YFP/SpCas9 targeting CRISPR/Cas significantly reduced the number of YFP fluorescent cells among mCherry-expressing cells (∼85.5% reduction compared with LacZ/SpCas9 targeting CRISPR/Cas) in the transfected retina of Thy1-YFP transgenic mice. In conclusion, our data suggest that a self-destructive "kamikaze" CRISPR/Cas system can be used as a robust tool for genome editing in the retina, without compromising on-target efficiency.
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Affiliation(s)
- Fan Li
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Centre, Sun Yat-sen University, Guangzhou, China
| | - Sandy S C Hung
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | | | - Jiang-Hui Wang
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Australia
| | - Vicki Chrysostomou
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Australia
| | - Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Australia
| | - Vikrant Singh
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Kristof Wing
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Leilei Tu
- Department of Ophthalmology, Jinan University, Guangzhou, China
| | - James A Bender
- Wicking Dementia Research and Education Centre, University of Tasmania, Hobart, Australia
| | - Alice Pébay
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Australia
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia
| | - Anna E King
- Wicking Dementia Research and Education Centre, University of Tasmania, Hobart, Australia
| | - Anthony L Cook
- Wicking Dementia Research and Education Centre, University of Tasmania, Hobart, Australia
| | - Raymond C B Wong
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Australia
| | - Alex W Hewitt
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Australia
| | - Guei-Sheung Liu
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Australia
- Department of Ophthalmology, Jinan University, Guangzhou, China
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15
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Comitato A, Schiroli D, Montanari M, Marigo V. Calpain Activation Is the Major Cause of Cell Death in Photoreceptors Expressing a Rhodopsin Misfolding Mutation. Mol Neurobiol 2019; 57:589-599. [PMID: 31401765 DOI: 10.1007/s12035-019-01723-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 07/26/2019] [Indexed: 10/26/2022]
Abstract
The majority of mutations in rhodopsin (RHO) cause misfolding of the protein and has been linked to degeneration of photoreceptor cells in the retina. A lot of attention has been set on targeting ER stress for the development of new therapies for inherited retinal degeneration caused by mutations in the RHO gene. Nevertheless, the cell death pathway activated by RHO misfolded protein is still debated. In this study, we analyzed the retina of the knock-in mouse expressing the P23H misfolded mutant RHO. We found persistent unfolded protein response (UPR) during degeneration. Interestingly, long-term stimulation of the PERK branch of ER stress had a protective effect by phosphorylating nuclear factor erythroid 2-related factor 2 (NRF2) transcription factor, associated with antioxidant responses. Otherwise, we provide evidence that increased intracellular calcium and activation of calpains strongly correlated with rod photoreceptor cell death. By blocking calpain activity, we significantly decreased the activation of caspase-7 and apoptosis-inducing factor (AIF), two cell death effectors, and cell demise, and effectively protected the retina from degeneration caused by the P23H dominant mutation in RHO.
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Affiliation(s)
- Antonella Comitato
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi, 287, 41125, Modena, Italy
| | - Davide Schiroli
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi, 287, 41125, Modena, Italy
| | - Monica Montanari
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi, 287, 41125, Modena, Italy
| | - Valeria Marigo
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi, 287, 41125, Modena, Italy.
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16
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Marinko J, Huang H, Penn WD, Capra JA, Schlebach JP, Sanders CR. Folding and Misfolding of Human Membrane Proteins in Health and Disease: From Single Molecules to Cellular Proteostasis. Chem Rev 2019; 119:5537-5606. [PMID: 30608666 PMCID: PMC6506414 DOI: 10.1021/acs.chemrev.8b00532] [Citation(s) in RCA: 145] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Indexed: 12/13/2022]
Abstract
Advances over the past 25 years have revealed much about how the structural properties of membranes and associated proteins are linked to the thermodynamics and kinetics of membrane protein (MP) folding. At the same time biochemical progress has outlined how cellular proteostasis networks mediate MP folding and manage misfolding in the cell. When combined with results from genomic sequencing, these studies have established paradigms for how MP folding and misfolding are linked to the molecular etiologies of a variety of diseases. This emerging framework has paved the way for the development of a new class of small molecule "pharmacological chaperones" that bind to and stabilize misfolded MP variants, some of which are now in clinical use. In this review, we comprehensively outline current perspectives on the folding and misfolding of integral MPs as well as the mechanisms of cellular MP quality control. Based on these perspectives, we highlight new opportunities for innovations that bridge our molecular understanding of the energetics of MP folding with the nuanced complexity of biological systems. Given the many linkages between MP misfolding and human disease, we also examine some of the exciting opportunities to leverage these advances to address emerging challenges in the development of therapeutics and precision medicine.
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Affiliation(s)
- Justin
T. Marinko
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Hui Huang
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Wesley D. Penn
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - John A. Capra
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department
of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37245, United States
| | - Jonathan P. Schlebach
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Charles R. Sanders
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
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17
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Ortega JT, Parmar T, Jastrzebska B. Flavonoids enhance rod opsin stability, folding, and self-association by directly binding to ligand-free opsin and modulating its conformation. J Biol Chem 2019; 294:8101-8122. [PMID: 30944172 DOI: 10.1074/jbc.ra119.007808] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/27/2019] [Indexed: 12/29/2022] Open
Abstract
Rhodopsin (Rho) is a visual G protein-coupled receptor expressed in the rod photoreceptors of the eye, where it mediates transmission of a light signal into a cell and converts this signal into a nerve impulse. More than 100 mutations in Rho are linked to various ocular impairments, including retinitis pigmentosa (RP). Accordingly, much effort has been directed toward developing ligands that target Rho and improve its folding and stability. Natural compounds may provide another viable approach to such drug discovery efforts. The dietary polyphenol compounds, ubiquitously present in fruits and vegetables, have beneficial effects in several eye diseases. However, the underlying mechanism of their activity is not fully understood. In this study, we used a combination of computational methods, biochemical and biophysical approaches, including bioluminescence resonance energy transfer, and mammalian cell expression systems to clarify the effects of four common bioactive flavonoids (quercetin, myricetin, and their mono-glycosylated forms quercetin-3-rhamnoside and myricetrin) on rod opsin stability, function, and membrane organization. We observed that by directly interacting with ligand-free opsin, flavonoids modulate its conformation, thereby causing faster entry of the retinal chromophore into its binding pocket. Moreover, flavonoids significantly increased opsin stability, most likely by introducing structural rigidity and promoting receptor self-association within the biological membranes. Of note, the binding of flavonoids to an RP-linked P23H opsin variant partially restored its normal cellular trafficking. Together, our results suggest that flavonoids could be utilized as lead compounds in the development of effective nonretinoid therapeutics for managing RP-related retinopathies.
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Affiliation(s)
- Joseph T Ortega
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Tanu Parmar
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Beata Jastrzebska
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
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18
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Roushar FJ, Gruenhagen TC, Penn WD, Li B, Meiler J, Jastrzebska B, Schlebach JP. Contribution of Cotranslational Folding Defects to Membrane Protein Homeostasis. J Am Chem Soc 2018; 141:204-215. [PMID: 30537820 DOI: 10.1021/jacs.8b08243] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Membrane proteins are prone to misfolding and degradation within the cell, yet the nature of the conformational defects involved in this process remain poorly understood. The earliest stages of membrane protein folding are mediated by the Sec61 translocon, a molecular machine that facilitates the lateral partitioning of the polypeptide into the membrane. Proper membrane integration is an essential prerequisite for folding of the nascent chain. However, the marginal energetic drivers of this reaction suggest the translocon may operate with modest fidelity. In this work, we employed biophysical modeling in conjunction with quantitative biochemical measurements in order to evaluate the extent to which cotranslational folding defects influence membrane protein homeostasis. Protein engineering was employed to selectively perturb the topological energetics of human rhodopsin, and the expression and cellular trafficking of engineered variants were quantitatively compared. Our results reveal clear relationships between topological energetics and the efficiency of rhodopsin biogenesis, which appears to be limited by the propensity of a polar transmembrane domain to achieve its correct topological orientation. Though the polarity of this segment is functionally constrained, we find that its topology can be stabilized in a manner that enhances biogenesis without compromising the functional properties of rhodopsin. Furthermore, sequence alignments reveal this topological instability has been conserved throughout the course of evolution. These results suggest that topological defects significantly contribute to the inefficiency of membrane protein folding in the cell. Additionally, our findings suggest that the marginal stability of rhodopsin may represent an evolved trait.
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Affiliation(s)
- Francis J Roushar
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Timothy C Gruenhagen
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Wesley D Penn
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Bian Li
- Department of Chemistry , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Jens Meiler
- Department of Chemistry , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Beata Jastrzebska
- Department of Pharmacology , Case Western Reserve University , Cleveland , Ohio 44106 , United States
| | - Jonathan P Schlebach
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
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19
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Sokolov M, Yadav RP, Brooks C, Artemyev NO. Chaperones and retinal disorders. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2018; 114:85-117. [PMID: 30635087 DOI: 10.1016/bs.apcsb.2018.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Defects in protein folding and trafficking are a common cause of photoreceptor degeneration, causing blindness. Photoreceptor cells present an unusual challenge to the protein folding and transport machinery due to the high rate of protein synthesis, trafficking and the renewal of the outer segment, a primary cilium that has been modified into a specialized light-sensing compartment. Phototransduction components, such as rhodopsin and cGMP-phosphodiesterase, and multimeric ciliary transport complexes, such as the BBSome, are hotspots for mutations that disrupt proteostasis and lead to the death of photoreceptors. In this chapter, we review recent studies that advance our understanding of the chaperone and transport machinery of phototransduction proteins.
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Affiliation(s)
- Maxim Sokolov
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | - Ravi P Yadav
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Celine Brooks
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA, United States.
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20
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Mohlin C, Delbro D, Kvanta A, Johansson K. Evaluation of Congo Red Staining in Degenerating Porcine Photoreceptors In Vitro: Protective Effects by Structural and Trophic Support. J Histochem Cytochem 2018; 66:631-641. [PMID: 29624116 PMCID: PMC6116089 DOI: 10.1369/0022155418768222] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 03/07/2018] [Indexed: 11/22/2022] Open
Abstract
Congo red (CR) is a histological stain used for the detection of extracellular amyloids mediating various neurodegenerative diseases. Given that damaged photoreceptors appear to degenerate similarly to other nerve cells, CR staining was evaluated in experimentally injured porcine retina. CR staining appeared mostly as discrete cytosolic deposits with no obvious plaque formation during the investigated time period. Increases of CR labeling coincided temporally with the known accumulation of mislocalized opsins and increases of cell death. Coculture, either with human retinal pigment epithelium (ARPE) or human neural progenitor (ReN) cells, was accompanied by a significant reduction of CR labeling. Of particular interest was the reduction of CR labeling in cone photoreceptors, which are important for the perception of color and fine details and afflicted in age-related macular degeneration (AMD). Electron microscopy revealed inclusions in the inner segment, cell body, and occasionally synaptic terminals of photoreceptor cells in cultured specimens. Closer examinations indicated the presence of different types of inclusions resembling protein aggregates as well as inclusion bodies. The current results indicate that injury-related response resulted in accumulation of CR deposits in photoreceptor cells, and that trophic and/or structural support attenuated this response.
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Affiliation(s)
- Camilla Mohlin
- Department of Chemistry and Biomedicine,
Linnaeus University, Kalmar, Sweden
| | - Dick Delbro
- School of Medical Sciences, Örebro University,
Örebro, Sweden
| | - Anders Kvanta
- Department of Clinical Neuroscience, Section for
Ophthalmology and Vision, St. Erik Eye Hospital, Karolinska Institutet,
Stockholm, Sweden
| | - Kjell Johansson
- Department of Science, Kristianstad University,
Kristianstad, Sweden
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21
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Đorđević B, Sokolović D, Cvetković T, Jevtović-Stoimenov T, Despotović M, Veljković A, Bašić J, Đukić D, Stević N, Veličkov A, Milenković J, Milošević S. EFFECTS OF METFORMIN ON PARAMETERS OF OXIDATIVE DAMAGE IN THE RETINA OF RATS WITH IMPAIRED GLUCOSE TOLERANCE. ACTA MEDICA MEDIANAE 2017. [DOI: 10.5633/amm.2017.0412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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22
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Butler MR, Ma H, Yang F, Belcher J, Le YZ, Mikoshiba K, Biel M, Michalakis S, Iuso A, Križaj D, Ding XQ. Endoplasmic reticulum (ER) Ca 2+-channel activity contributes to ER stress and cone death in cyclic nucleotide-gated channel deficiency. J Biol Chem 2017; 292:11189-11205. [PMID: 28495882 DOI: 10.1074/jbc.m117.782326] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/01/2017] [Indexed: 02/05/2023] Open
Abstract
Endoplasmic reticulum (ER) stress and mislocalization of improperly folded proteins have been shown to contribute to photoreceptor death in models of inherited retinal degenerative diseases. In particular, mice with cone cyclic nucleotide-gated (CNG) channel deficiency, a model for achromatopsia, display both early-onset ER stress and opsin mistrafficking. By 2 weeks of age, these mice show elevated signaling from all three arms of the ER-stress pathway, and by 1 month, cone opsin is improperly distributed away from its normal outer segment location to other retinal layers. This work investigated the role of Ca2+-release channels in ER stress, protein mislocalization, and cone death in a mouse model of CNG-channel deficiency. We examined whether preservation of luminal Ca2+ stores through pharmacological and genetic suppression of ER Ca2+ efflux protects cones by attenuating ER stress. We demonstrated that the inhibition of ER Ca2+-efflux channels reduced all three arms of ER-stress signaling while improving opsin trafficking to cone outer segments and decreasing cone death by 20-35%. Cone-specific gene deletion of the inositol-1,4,5-trisphosphate receptor type I (IP3R1) also significantly increased cone density in the CNG-channel-deficient mice, suggesting that IP3R1 signaling contributes to Ca2+ homeostasis and cone survival. Consistent with the important contribution of organellar Ca2+ signaling in this achromatopsia mouse model, significant differences in dynamic intraorganellar Ca2+ levels were detected in CNG-channel-deficient cones. These results thus identify a novel molecular link between Ca2+ homeostasis and cone degeneration, thereby revealing novel therapeutic targets to preserve cones in inherited retinal degenerative diseases.
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Affiliation(s)
| | | | - Fan Yang
- From the Departments of Cell Biology
| | | | - Yun-Zheng Le
- From the Departments of Cell Biology.,Internal Medicine, and.,Ophthalmology and.,the Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Katsuhiko Mikoshiba
- the Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Hirosawa Wako-shi, Saitama 351-0198, Japan
| | - Martin Biel
- the Center for Integrated Protein Science Munich (CIPSM) and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany, and
| | - Stylianos Michalakis
- the Center for Integrated Protein Science Munich (CIPSM) and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany, and
| | - Anthony Iuso
- the John A. Moran Eye Center, University of Utah, Salt Lake City, Utah 84132
| | - David Križaj
- the John A. Moran Eye Center, University of Utah, Salt Lake City, Utah 84132
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Lei L, Tzekov R, Li H, McDowell JH, Gao G, Smith WC, Tang S, Kaushal S. Inhibition or Stimulation of Autophagy Affects Early Formation of Lipofuscin-Like Autofluorescence in the Retinal Pigment Epithelium Cell. Int J Mol Sci 2017; 18:ijms18040728. [PMID: 28353645 PMCID: PMC5412314 DOI: 10.3390/ijms18040728] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 12/22/2022] Open
Abstract
The accumulation of lipofuscin in the retinal pigment epithelium (RPE) is dependent on the effectiveness of photoreceptor outer segment material degradation. This study explored the role of autophagy in the fate of RPE lipofuscin degradation. After seven days of feeding with either native or modified rod outer segments, ARPE-19 cells were treated with enhancers or inhibitors of autophagy and the autofluorescence was detected by fluorescence-activated cell sorting. Supplementation with different types of rod outer segments increased lipofuscin-like autofluorescence (LLAF) after the inhibition of autophagy, while the induction of autophagy (e.g., application of rapamycin) decreased LLAF. The effects of autophagy induction were further confirmed by Western blotting, which showed the conversion of LC3-I to LC3-II, and by immunofluorescence microscopy, which detected the lysosomal activity of the autophagy inducers. We also monitored LLAF after the application of several autophagy inhibitors by RNA-interference and confocal microscopy. The results showed that, in general, the inhibition of the autophagy-related proteins resulted in an increase in LLAF when cells were fed with rod outer segments, which further confirms the effect of autophagy in the fate of RPE lipofuscin degradation. These results emphasize the complex role of autophagy in modulating RPE autofluorescence and confirm the possibility of the pharmacological clearance of RPE lipofuscin by small molecules.
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Affiliation(s)
- Lei Lei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, No.54 South Xianlie Road, Guangzhou 510060, China.
- Department of Ophthalmology, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
| | - Radouil Tzekov
- Department of Ophthalmology, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
- Department of Ophthalmology, University of South Florida, 13127 USF Magnolia Drive, Tampa, FL 33612, USA.
- The Roskamp Institute, 2040 Whitfield Avenue, Sarasota, FL 34243, USA.
| | - Huapeng Li
- Gene Therapy Center, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
| | - J Hugh McDowell
- The Department of Ophthalmology, University of Florida Health Science Center, 1600 SW Archer Road, Gainesville, FL 32610, USA.
| | - Guangping Gao
- Gene Therapy Center, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
| | - W Clay Smith
- The Department of Ophthalmology, University of Florida Health Science Center, 1600 SW Archer Road, Gainesville, FL 32610, USA.
| | - Shibo Tang
- Aier School of Ophthalmology, Central South University, Floor 4, New Century Building, 198# Furong Middle Road, Changsha 410015, China.
| | - Shalesh Kaushal
- Department of Ophthalmology, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
- VRMI, 6205 NW 81st Drive, Gainesville, FL 32653, USA.
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24
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Dong X, Herrera-Hernández MG, Ramon E, Garriga P. Docosahexaenoic acid phospholipid differentially modulates the conformation of G90V and N55K rhodopsin mutants associated with retinitis pigmentosa. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:975-981. [PMID: 28212859 DOI: 10.1016/j.bbamem.2017.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 02/09/2017] [Accepted: 02/11/2017] [Indexed: 11/26/2022]
Abstract
Rhodopsin is the visual photoreceptor of the retinal rod cells that mediates dim light vision and a prototypical member of the G protein-coupled receptor superfamily. The structural stability and functional performance of rhodopsin are modulated by membrane lipids. Docosahexaenoic acid has been shown to interact with native rhodopsin but no direct evidence has been established on the effect of such lipid on the stability and regeneration of rhodopsin mutants associated with retinal diseases. The stability and regeneration of two thermosensitive mutants G90V and N55K, associated with the retinal degenerative disease retinitis pigmentosa, have been analyzed in docosohexaenoic phospholipid (1,2-didocosa-hexaenoyl-sn-glycero-3-phosphocholine; DDHA-PC) liposomes. G90V mutant reconstituted in DDHA-PC liposomes significantly increased its thermal stability, but N55K mutant showed similar thermal sensitivity both in dodecyl maltoside detergent solution and in DDHA-PC liposomes. The retinal release process, measured by fluorescence spectroscopy, became faster in the lipid system for the two mutants. The opsin conformation was stabilized for the G90V mutant allowing improved retinal uptake whereas no chromophore binding could be detected for N55K opsin after photoactivation. The results emphasize the distinct role of DHA on different phenotypic rhodopsin mutations associated with classical (G90V) and sector (N55K) retinitis pigmentosa.
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Affiliation(s)
- Xiaoyun Dong
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
| | - María Guadalupe Herrera-Hernández
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
| | - Eva Ramon
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
| | - Pere Garriga
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain.
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25
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Miao G, Zhao YG, Zhao H, Ji C, Sun H, Chen Y, Zhang H. Mice deficient in the Vici syndrome gene Epg5 exhibit features of retinitis pigmentosa. Autophagy 2016; 12:2263-2270. [PMID: 27715390 DOI: 10.1080/15548627.2016.1238554] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Autophagy helps to maintain cellular homeostasis by removing misfolded proteins and damaged organelles, and generally acts as a cytoprotective mechanism for neuronal survival. Here we showed that mice deficient in the Vici syndrome gene Epg5, which is required for autophagosome maturation, show accumulation of ubiquitin-positive inclusions and SQSTM1 aggregates in various retinal cell types. In epg5-/- retinas, photoreceptor function is greatly impaired, and degenerative features including progressively reduced numbers of photoreceptor cells and increased numbers of apoptotic cells in the outer nuclear layer are observed, while the morphology of other parts of the retina is not severely affected. Downstream targets of the unfolded protein response (UPR), including the death inducer DDIT3/CHOP, and also levels of cleaved CASP3 (caspase 3), are elevated in epg5-/- retinas. Thus, apoptotic photoreceptor cell death in epg5-/- retinas may result from the elevated UPR. Our results reveal that Epg5-deficient mice recapitulate key characteristics of retinitis pigmentosa and thus may provide a valuable model for investigating the molecular mechanism of photoreceptor degeneration.
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Affiliation(s)
- Guangyan Miao
- a Department of Immunology , Peking University School of Basic Medical Science , Beijing , China.,b State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences , Beijing , China
| | - Yan G Zhao
- b State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences , Beijing , China
| | - Hongyu Zhao
- b State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences , Beijing , China
| | - Cuicui Ji
- b State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences , Beijing , China
| | - Huayu Sun
- b State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences , Beijing , China
| | - Yingyu Chen
- a Department of Immunology , Peking University School of Basic Medical Science , Beijing , China
| | - Hong Zhang
- b State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences , Beijing , China
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26
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Biswas P, Chavali VRM, Agnello G, Stone E, Chakarova C, Duncan JL, Kannabiran C, Homsher M, Bhattacharya SS, Naeem MA, Kimchi A, Sharon D, Iwata T, Riazuddin S, Reddy GB, Hejtmancik JF, Georgiou G, Riazuddin SA, Ayyagari R. A missense mutation in ASRGL1 is involved in causing autosomal recessive retinal degeneration. Hum Mol Genet 2016; 25:2483-2497. [PMID: 27106100 DOI: 10.1093/hmg/ddw113] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 03/22/2016] [Accepted: 04/11/2016] [Indexed: 12/31/2022] Open
Abstract
Inherited retinal dystrophies are a group of genetically heterogeneous conditions with broad phenotypic heterogeneity. We analyzed a large five-generation pedigree with early-onset recessive retinal degeneration to identify the causative mutation. Linkage analysis and homozygosity mapping combined with exome sequencing were carried out to map the disease locus and identify the p.G178R mutation in the asparaginase like-1 gene (ASRGL1), segregating with the retinal dystrophy phenotype in the study pedigree. ASRGL1 encodes an enzyme that catalyzes the hydrolysis of L-asparagine and isoaspartyl-peptides. Studies on the ASRGL1 expressed in Escherichia coli and transiently transfected mammalian cells indicated that the p.G178R mutation impairs the autocatalytic processing of this enzyme resulting in the loss of functional ASRGL1 and leaving the inactive precursor protein as a destabilized and aggregation-prone protein. A zebrafish model overexpressing the mutant hASRGL1 developed retinal abnormalities and loss of cone photoreceptors. Our studies suggest that the p.G178R mutation in ASRGL1 leads to photoreceptor degeneration resulting in progressive vision loss.
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Affiliation(s)
- Pooja Biswas
- Shiley Eye Institute, University of California San Diego, La Jolla, CA, USA
| | - Venkata Ramana Murthy Chavali
- Ophthalmology, University of Pennsylvania, Philadelphia, PA, USA.,Ophthalmology, University of Pennsylvania, Philadelphia, PA, USA
| | - Giulia Agnello
- Departments of Biomedical and Chemical Engineering, Molecular Biosciences, Section of Molecular Genetics and Microbiology, and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Everett Stone
- Departments of Biomedical and Chemical Engineering, Molecular Biosciences, Section of Molecular Genetics and Microbiology, and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | | | - Jacque L Duncan
- Ophthalmology, University of California San Francisco, San Francisco, CA, USA
| | - Chitra Kannabiran
- Kallam Anji Reddy Molecular Genetics Laboratory, L V Prasad Eye Institute (LVPEI), Kallam Anji Reddy Campus, L V Prasad Marg, Hyderabad 500 034, India
| | - Melissa Homsher
- Ophthalmology, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Adva Kimchi
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Dror Sharon
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Shaikh Riazuddin
- Allama Iqbal Medical College, University of Health Sciences Lahore, Pakistan.,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | | | | | - George Georgiou
- Departments of Biomedical and Chemical Engineering, Molecular Biosciences, Section of Molecular Genetics and Microbiology, and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - S Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Radha Ayyagari
- Shiley Eye Institute, University of California San Diego, La Jolla, CA, USA
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27
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New Developments in Murine Imaging for Assessing Photoreceptor Degeneration In Vivo. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:269-75. [PMID: 26427421 DOI: 10.1007/978-3-319-17121-0_36] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Optical Coherence Tomography (OCT) is a powerful clinical tool that measures near infrared light backscattered from the eye and other tissues. OCT is used for assessing changes in retinal structure, including layer thicknesses, detachments and the presence of drusen in patient populations. Our custom-built OCT system for the mouse eye quantitatively images all layers of the neural retinal, the RPE, Bruchs' membrane and the choroid. Longitudinal assessment of the same retinal region reveals that the relative intensities of retinal layers are highly stable in healthy tissue, but show progressive increases in intensity in a model of retinal degeneration. The observed changes in OCT signal have been correlated with ultrastructural disruptions that were most dramatic in the inner segments and nuclei of the rods. These early changes in photoreceptor structure coincided with activation of retinal microglia, which migrated vertically from the inner to the outer retina to phagocytose photoreceptor cell bodies (Levine et al., Vis Res 102:71-79, 2014). We conclude that quantitative analysis of OCT light scattering signals may be a useful tool for early detection and subcellular localization of cell stress prior to cell death, and for assessing the progression of degenerative disease over time. Future efforts to develop sensitive approaches for monitoring microglial dynamics in vivo may likewise elucidate earlier signs of cellular stress during retinal degeneration.
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28
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Cai X, Chen L, McGinnis JF. Correlation of ER stress and retinal degeneration in tubby mice. Exp Eye Res 2015; 140:130-138. [PMID: 26325328 DOI: 10.1016/j.exer.2015.08.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 07/09/2015] [Accepted: 08/25/2015] [Indexed: 11/17/2022]
Abstract
Mutation of the Tub gene results in the mislocalization of photoreceptor-specific proteins and eventually retinal degeneration. However, the exact mechanism underlying the retinal degeneration remains largely unknown. In this study, we discovered that the expression of endoplasmic reticulum (ER) stress markers, IRE1, ATF6, eIF2α, GRP78/BiP, and XBP-1, is up regulated during tubby retinal development. The dynamics of the expression of these genes are time-dependent and coincided with the time-course of photoreceptor death. Our data also demonstrated that ER stress triggers apoptosis via down-regulation of Bcl2, up-regulation of CHOP and the activation of NF-кB signaling.
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Affiliation(s)
- Xue Cai
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States.
| | - Lijuan Chen
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States
| | - James F McGinnis
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States; Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States.
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29
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Xu M, Gelowani V, Eblimit A, Wang F, Young MP, Sawyer BL, Zhao L, Jenkins G, Creel DJ, Wang K, Ge Z, Wang H, Li Y, Hartnett ME, Chen R. ATF6 Is Mutated in Early Onset Photoreceptor Degeneration With Macular Involvement. Invest Ophthalmol Vis Sci 2015; 56:3889-95. [PMID: 26070061 DOI: 10.1167/iovs.15-16778] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Photoreceptor degeneration (PRD) is a genetically heterogeneous retinal disorder. Although a number of genes involved in PRD have been identified, their genetic basis remains unknown in a significant number of patients. In this study, we aimed to identify novel disease-causing genes of PRD. METHODS Comprehensive ocular examinations were performed in a 2-year-old patient diagnosed with early onset PRD. Retinal capture sequencing was performed to screen causative mutations in known retinal disease-causing loci. Whole-exome sequencing (WES) and a series of variant-filtering strategies were applied for identifying novel disease-causing genes. Retina ATF6 expression was confirmed by immunohistochemistry. RT-PCR was performed to identify ATF6 mRNA in the patient. RESULTS The patient showed typical PRD features, with macular involvement and ellipsoid zone irregularities. Results of retinal capture sequencing were negative. WES data led to identification of biallelic loss-of-function mutations in the ATF6 gene. The first variant generates a premature stop codon (NCBI accession no. NM_007348: c.1126C>T, p.R376*) and the second variant affects a splicing donor site (NM_007348: c.1533+1G>C). Sanger sequencing confirmed the 2 alleles are from 1 parent each. Both of the variants are extremely rare in the population. The splicing variant causes either intron inclusion or exon skipping in the patient, thus severely disrupting ATF6 functional domains. ATF6 is expressed in three neuronal cell layers of mouse retina. CONCLUSIONS Our results support ATF6 as a novel disease-causing gene for PRD and suggest that disrupted protein quality control mechanisms may be a novel pathological mechanism underlying human retinal degeneration.
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Affiliation(s)
- Mingchu Xu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States
| | - Violet Gelowani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States
| | - Aiden Eblimit
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States
| | - Feng Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States
| | - Marielle P Young
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Briana L Sawyer
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Li Zhao
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States 4Structural and Computational Biology and Molecular Biophysics
| | - Glen Jenkins
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Donnell J Creel
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Keqing Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States
| | - Zhongqi Ge
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States
| | - Hui Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States
| | - M Elizabeth Hartnett
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States 4Structural and Computational Biology and Molecular Biophysics
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30
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Dong X, Ramon E, Herrera-Hernández MG, Garriga P. Phospholipid Bicelles Improve the Conformational Stability of Rhodopsin Mutants Associated with Retinitis Pigmentosa. Biochemistry 2015; 54:4795-804. [PMID: 26181234 DOI: 10.1021/acs.biochem.5b00435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mutations in the visual photoreceptor rhodopsin are the cause of the retinal degenerative disease retinitis pigmentosa. Some naturally occurring mutations can lead to protein conformational instability. Two such mutations, N55K and G90V, in the first and second transmembrane helices of the receptor, have been associated with sector and classical retinitis pigmentosa, respectively, and showed enhanced thermal sensitivity. We have carefully analyzed the effect of phospholipid bicelles on the stability and ligand binding properties of these two mutants and compared it with those of the detergent-solubilized samples. We have used a phospholipid bilayer consisting of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC). We find that DMPC/DHPC bicelles dramatically increase the thermal stability of the rhodopsin mutants G90V and N55K. The chromophore stability and regeneration of the mutants were also increased in bicelles when compared to their behavior in a dodecyl maltoside detergent solution. The retinal release process was slowed in bicelles, and chromophore entry, after illumination, was improved for the G90V mutant but not for N55K. Furthermore, fluorescence spectroscopy measurements showed that bicelles allowed more exogenous retinal binding to the photoactivated G90V mutant than in a detergent solution. In contrast, N55K could not reposition any chromophore either in the detergent or in bicelles. The results demonstrate that DMPC/DHPC bicelles can counteract the destabilizing effect of the disease-causing mutations and can modulate the structural changes in the ensuing receptor photoactivation in a distinct specific manner for different retinitis pigmentosa mutant phenotypes.
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Affiliation(s)
- Xiaoyun Dong
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
| | - Eva Ramon
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
| | - María Guadalupe Herrera-Hernández
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
| | - Pere Garriga
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
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31
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Schlebach JP, Narayan M, Alford C, Mittendorf KF, Carter BD, Li J, Sanders CR. Conformational Stability and Pathogenic Misfolding of the Integral Membrane Protein PMP22. J Am Chem Soc 2015; 137:8758-68. [PMID: 26102530 PMCID: PMC4507940 DOI: 10.1021/jacs.5b03743] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
![]()
Despite broad biochemical
relevance, our understanding of the physiochemical
reactions that limit the assembly and cellular trafficking of integral
membrane proteins remains superficial. In this work, we report the
first experimental assessment of the relationship between the conformational
stability of a eukaryotic membrane protein and the degree to which
it is retained by cellular quality control in the secretory pathway.
We quantitatively assessed both the conformational equilibrium and
cellular trafficking of 12 variants of the α-helical membrane
protein peripheral myelin protein 22 (PMP22), the intracellular misfolding
of which is known to cause peripheral neuropathies associated with
Charcot–Marie–Tooth disease (CMT). We show that the
extent to which these mutations influence the energetics of Zn(II)-mediated
PMP22 folding is proportional to the observed reduction in cellular
trafficking efficiency. Strikingly, quantitative analyses also reveal
that the reduction of motor nerve conduction velocities in affected
patients is proportional to the extent of the mutagenic destabilization.
This finding provides compelling evidence that the effects of these
mutations on the energetics of PMP22 folding lie at the heart of the
molecular basis of CMT. These findings highlight conformational stability
as a key factor governing membrane protein biogenesis and suggest
novel therapeutic strategies for CMT.
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Affiliation(s)
| | | | - Catherine Alford
- #Flow Cytometry Core, Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee 37232, United States
| | | | | | - Jun Li
- ⊥Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee 37232, United States
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32
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Role of post-translational modifications on structure, function and pharmacology of class C G protein-coupled receptors. Eur J Pharmacol 2015; 763:233-40. [PMID: 25981296 DOI: 10.1016/j.ejphar.2015.05.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 03/06/2015] [Accepted: 05/11/2015] [Indexed: 11/22/2022]
Abstract
G protein-coupled receptors are divided into three classes (A, B and C) based on homology of their seven transmembrane domains. Class C is the smallest class with 22 human receptor subtypes including eight metabotropic glutamate (mGlu1-8) receptors, two GABAB receptors (GABAB1 and GABAB2), three taste receptors (T1R1-3), one calcium-sensing (CaS) receptor, one GPCR, class C, group 6, subtype A (GPRC6) receptor, and seven orphan receptors. G protein-coupled receptors undergo a number of post-translational modifications, which regulate their structure, function and/or pharmacology. Here, we review the existence of post-translational modifications in class C G protein-coupled receptors and their regulatory roles, with particular focus on glycosylation, phosphorylation, ubiquitination, SUMOylation, disulphide bonding and lipidation.
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33
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Burtscher V, Schicker K, Novikova E, Pöhn B, Stockner T, Kugler C, Singh A, Zeitz C, Lancelot ME, Audo I, Leroy BP, Freissmuth M, Herzig S, Matthes J, Koschak A. Spectrum of Cav1.4 dysfunction in congenital stationary night blindness type 2. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1838:2053-65. [PMID: 24796500 PMCID: PMC4065569 DOI: 10.1016/j.bbamem.2014.04.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/11/2014] [Accepted: 04/23/2014] [Indexed: 11/26/2022]
Abstract
Defective retinal synaptic transmission in patients affected with congenital stationary night blindness type 2 (CSNB2) can result from different dysfunction phenotypes in Cav1.4 L-type calcium channels. Here we investigated two prototypical Cav1.4 variants from either end of the functional spectrum. Using whole-cell and single-channel patch-clamp techniques, we provide analysis of the biophysical characteristics of the point mutation L860P and the C-terminal truncating mutation R1827X. L860P showed a typical loss-of-function phenotype attributed to a reduced number of functional channels expressed at the plasma membrane as implied by gating current and non-stationary noise analyses. This phenotype can be rationalized, because the inserted proline is predicted to break an amphipatic helix close to the transmembrane segment IIIS1 and thus to reduce channel stability and promote misfolding. In fact, L860P was subject to an increased turnover. In contrast, R1827X displayed an apparent gain-of-function phenotype, i.e., due to a hyperpolarizing shift of the IV-curve and increased single-channel activity. However, truncation also resulted in the loss of functional C-terminal modulation and thus unmasked calcium-dependent inactivation. Thus R1827X failed to support continuous calcium influx. Current inactivation curtails the dynamic range of photoreceptors (e.g., when adapting to variation in illumination). Taken together, the analysis of two representative mutations that occur in CSNB2 patients revealed fundamental differences in the underlying defect. These may explain subtle variations in the clinical manifestation and must be taken into account, if channel function is to be restored by pharmacochaperones or related approaches.
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Affiliation(s)
- Verena Burtscher
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Klaus Schicker
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Elena Novikova
- University of Cologne, Department of Pharmacology and Center of Molecular Medicine, 50931 Cologne, Germany
| | - Birgit Pöhn
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Thomas Stockner
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Pharmacology, Währingerstrasse 13A, 1090 Wien, Austria
| | - Christof Kugler
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Anamika Singh
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, Innrain 80-82/III, 6020 Innsbruck, Austria
| | - Christina Zeitz
- INSERM, UMR_S968, Paris F-75012, France; CNRS, UMR_7210, Paris F-75012, France; UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France
| | - Marie-Elise Lancelot
- INSERM, UMR_S968, Paris F-75012, France; CNRS, UMR_7210, Paris F-75012, France; UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France
| | - Isabelle Audo
- INSERM, UMR_S968, Paris F-75012, France; CNRS, UMR_7210, Paris F-75012, France; UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France; Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris F-75012, France; UCL-Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Bart Peter Leroy
- Dept of Ophthalmology & Center for Medical Genetics, Ghent University Hospital & Ghent University, 9000 Ghent, Belgium
| | - Michael Freissmuth
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Pharmacology, Währingerstrasse 13A, 1090 Wien, Austria
| | - Stefan Herzig
- University of Cologne, Department of Pharmacology and Center of Molecular Medicine, 50931 Cologne, Germany
| | - Jan Matthes
- University of Cologne, Department of Pharmacology and Center of Molecular Medicine, 50931 Cologne, Germany
| | - Alexandra Koschak
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria.
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Sun L, Zhang H, Gu Z, Cao M, Li D, Chan P. Stereopsis impairment is associated with decreased color perception and worse motor performance in Parkinson's disease. Eur J Med Res 2014; 19:29. [PMID: 24886673 PMCID: PMC4046158 DOI: 10.1186/2047-783x-19-29] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 04/24/2014] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND We conducted this study is to investigate the correlation between stereopsis dysfunction and color perception, as well as whether stereopsis impairment is associated with motor dysfunction in patients with Parkinson's disease (PD). METHOD Our present study included 45 PD patients and 50 non-PD control patients attending the Movement Disorder Center at Xuanwu Hospital Capital Medical University in Beijing from July 2011 to November 2011. Neurologic evaluations and visual function assessments were conducted, and the results between two groups of patients were compared. RESULTS We found that the total error scores (TESs) and partial error scores (PESs) for red, green, blue and purple were all significantly higher in PD patients than in control patients. The limited grade on the FLY Stereo Acuity Test with LEA Symbols was significantly lower in PD patients than in control patients (P = 0.0001), whereas the percentage of abnormal stereopsis in PD patients was significantly higher than in control patients (42.2% vs. 12%; P = 0.001). Multiple linear regression analysis showed that PD patients with higher Hoehn and Yahr Scale stage, and those with decreased stereopsis had higher Unified Parkinson's Disease Rating Scale (UPDRS) motor scores and worse motor function. Furthermore, our study demonstrates that the UPDRS motor scores and total average number of the Purdue Pegboard Test scores of PD patients were significantly improved when they had taken their medications, and the TESs and PESs for green were lower in when they were off their medications. CONCLUSION Our results provide more information on the underlying mechanisms of vision, motor and stereopsis impairments in PD patients.
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Affiliation(s)
- Liang Sun
- Department of Neurology, Xuanwu Hospital of Capital Medical University, 45 Changchun Street, Beijing 100053, China.
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Lackman JJ, Markkanen PMH, Hogue M, Bouvier M, Petäjä-Repo UE. N-Glycan-dependent and -independent quality control of human δ opioid receptor N-terminal variants. J Biol Chem 2014; 289:17830-42. [PMID: 24798333 DOI: 10.1074/jbc.m114.566273] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Quality control (QC) in the endoplasmic reticulum (ER) scrutinizes newly synthesized proteins and directs them either to ER export or ER-associated degradation (ERAD). Here, we demonstrate that the human δ-opioid receptor (hδOR) is subjected to ERQC in both N-glycan-dependent and -independent manners. This was shown by investigating the biosynthesis and trafficking of wild-type and non-N-glycosylated F27C variants in metabolic pulse-chase assays coupled with flow cytometry and cell surface biotinylation. Both QC mechanisms distinguished the minute one-amino acid difference between the variants, targeting a large fraction of hδOR-Cys(27) to ERAD. However, the N-glycan-independent QC was unable to compensate the N-glycan-dependent pathway, and some incompletely folded non-N-glycosylated hδOR-Cys(27) reached the cell surface in conformation incompatible with ligand binding. The turnover of receptors associating with the molecular chaperone calnexin (CNX) was significantly slower for the hδOR-Cys(27), pointing to an important role of CNX in the hδOR N-glycan-dependent QC. This was further supported by the fact that inhibiting the co-translational interaction of hδOR-Cys(27) precursors with CNX led to their ERAD. Opioid receptor pharmacological chaperones released the CNX-bound receptors to ER export and, furthermore, were able to rescue the Cys(27) variant from polyubiquitination and retrotranslocation to the cytosol whether carrying N-glycans or not. Taken together, the hδOR appears to rely primarily on the CNX-mediated N-glycan-dependent QC that has the capacity to assist in folding, whereas the N-glycan-independent mechanism constitutes an alternative, although less accurate, system for directing misfolded/incompletely folded receptors to ERAD, possibly in altered cellular conditions.
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Affiliation(s)
- Jarkko J Lackman
- From the Department of Anatomy and Cell Biology and the Medical Research Center Oulu, Institute of Biomedicine, University of Oulu, FI-90014 Oulu, Finland and
| | - Piia M H Markkanen
- From the Department of Anatomy and Cell Biology and the Medical Research Center Oulu, Institute of Biomedicine, University of Oulu, FI-90014 Oulu, Finland and
| | - Mireille Hogue
- the Department of Biochemistry, Institute for Research in Immunology and Cancer and Groupe de Recherche Universitaire sur le Médicament, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Michel Bouvier
- the Department of Biochemistry, Institute for Research in Immunology and Cancer and Groupe de Recherche Universitaire sur le Médicament, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Ulla E Petäjä-Repo
- From the Department of Anatomy and Cell Biology and the Medical Research Center Oulu, Institute of Biomedicine, University of Oulu, FI-90014 Oulu, Finland and
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Zhang SX, Sanders E, Fliesler SJ, Wang JJ. Endoplasmic reticulum stress and the unfolded protein responses in retinal degeneration. Exp Eye Res 2014; 125:30-40. [PMID: 24792589 DOI: 10.1016/j.exer.2014.04.015] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 04/02/2014] [Accepted: 04/18/2014] [Indexed: 02/06/2023]
Abstract
The endoplasmic reticulum (ER) is the primary intracellular organelle responsible for protein and lipid biosynthesis, protein folding and trafficking, calcium homeostasis, and several other vital processes in cell physiology. Disturbance in ER function results in ER stress and subsequent activation of the unfolded protein response (UPR). The UPR up-regulates ER chaperones, reduces protein translation, and promotes clearance of cytotoxic misfolded proteins to restore ER homeostasis. If this vital process fails, the cell will be signaled to enter apoptosis, resulting in cell death. Sustained ER stress also can trigger an inflammatory response and exacerbate oxidative stress, both of which contribute synergistically to tissue damage. Studies performed over the past decade have implicated ER stress in a broad range of human diseases, including neurodegenerative diseases, cancer, diabetes, and vascular disorders. Several of these diseases also entail retinal dysfunction and degeneration caused by injury to retinal neurons and/or to the blood vessels that supply retinal cells with nutrients, trophic and homeostatic factors, oxygen, and other essential molecules, as well as serving as a conduit for removal of waste products and potentially toxic substances from the retina. Collectively, such injuries represent the leading cause of blindness world-wide in all age groups. Herein, we summarize recent progress on the study of ER stress and UPR signaling in retinal biology and discuss the molecular mechanisms and the potential clinical applications of targeting ER stress as a new therapeutic approach to prevent and treat neuronal degeneration in the retina.
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Affiliation(s)
- Sarah X Zhang
- Departments of Ophthalmology and Biochemistry, University at Buffalo, The State University of New York, Buffalo, NY, USA; SUNY Eye Institute, Buffalo, NY, USA.
| | - Emily Sanders
- Department of Medicine, Endocrinology and Diabetes, Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Steven J Fliesler
- Departments of Ophthalmology and Biochemistry, University at Buffalo, The State University of New York, Buffalo, NY, USA; SUNY Eye Institute, Buffalo, NY, USA; Research Service, Veterans Administration Western New York Healthcare System, Buffalo, NY, USA
| | - Joshua J Wang
- Departments of Ophthalmology and Biochemistry, University at Buffalo, The State University of New York, Buffalo, NY, USA; SUNY Eye Institute, Buffalo, NY, USA
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Lei L, Tzekov R, McDowell JH, Smith WC, Tang S, Kaushal S. Formation of lipofuscin-like material in the RPE Cell by different components of rod outer segments. Exp Eye Res 2013; 112:57-67. [PMID: 23603319 PMCID: PMC4069600 DOI: 10.1016/j.exer.2013.04.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Revised: 04/03/2013] [Accepted: 04/09/2013] [Indexed: 01/10/2023]
Abstract
The mechanisms that control the natural rate of lipofuscin accumulation in the retinal pigment epithelial (RPE) cell and its stability over time are not well understood. Similarly, the contributions of retinoids, phospholipids and oxidation to the rate of accumulation of lipofuscin are uncertain. The experiments in this study were conducted to explore the individual contribution of rod outer segments (ROS) components to lipofuscin formation and its accumulation and stability over time. During the period of 14 days incubation of ROS, lipofuscin-like autofluorescence (LLAF) determined at two wavelengths (530 and 585 nm) by fluorescence-activated cell sorting (FACS) was measured from RPE cells. The autofluorescence increased in an exponential manner with a strong linear component between days 1 and 7. The magnitude of the increase was larger in cells incubated with 4-hydroxynonenal (HNE-ROS) compared with cells incubated with either bleached or unbleached ROS, but with a different spectral profile. A small (10-15%) decrease in LLAF was observed after stopping the ROS feeding for 14 days. The phagocytosis rate of HNE-ROS was higher than that of either bleached or unbleached ROS during the first 24 h of supplementation. Among the different ROS components, the increase of LLAF was highest in cells incubated with all-trans-retinal. Surprisingly, incubation with 11-cis-retinal and 9-cis-retinal also resulted in strong LLAF increase, comparable to the increase induced by all-trans-retinal. Supplementation with liposomes containing phosphatidylethanolamine (22: 6-PE) and phosphatidylcholine (18:1-PC) also increased LLAF, while incubation with opsin had little effect. Cells incubated with retinoids demonstrated strong dose-dependence in LLAF increase, and the magnitude of the increase was 2-3 times higher at 585 nm compared to 530 nm, while cells incubated with liposomes showed little dose-dependence and similar increase at both wavelengths. Very little difference in LLAF was noted between cells incubated with either unbleached or bleached ROS under any conditions. In summary, results from this study suggest that supplementation with various ROS components can lead to an increase in LLAF, although the autofluorescence generated by the different classes of components has distinct spectral profiles, where the autofluorescence induced by retinoids results in a spectral profile closest to the one observed from human lipofuscin. Future fluorescence characterization of LLAF in vitro would benefit from an analysis of multiple wavelengths to better match the spectral characteristics of lipofuscin in vivo.
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Affiliation(s)
- Lei Lei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, No. 54 South Xianlie Road, Guangzhou 510060, China
- The Department of Ophthalmology, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA
| | - Radouil Tzekov
- The Department of Ophthalmology, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA
| | - J. Hugh McDowell
- The Department of Ophthalmology, University of Florida Health Science Center, 1600 SW Archer Road, Gainesville, FL 32610, USA
| | - Wesley C. Smith
- The Department of Ophthalmology, University of Florida Health Science Center, 1600 SW Archer Road, Gainesville, FL 32610, USA
| | - Shibo Tang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, No. 54 South Xianlie Road, Guangzhou 510060, China
| | - Shalesh Kaushal
- The Department of Ophthalmology, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA
- Retina Specialty Institute, 6717 NW 11th Place, Gainesville, FL 32605, USA
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Sustained protection against photoreceptor degeneration in tubby mice by intravitreal injection of nanoceria. Biomaterials 2012; 33:8771-81. [PMID: 22959465 DOI: 10.1016/j.biomaterials.2012.08.030] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 08/13/2012] [Indexed: 02/05/2023]
Abstract
We previously reported that nanoceria can slow retinal degeneration in the tubby mouse for two weeks by multiple systemic injections. However, the long-term protection of retinal structure and function by directly deliver of nanoceria to the eye had not been explored. In this study, 172 ng of nanoceria in 1 μl saline (1 mm) were intravitreally injected into tubby P7 pups and assays were performed at P28, P49, P80 and P120. The expression of antioxidant associated genes and photoreceptor-specific genes was significantly up regulated, the mislocalization of rod and cone opsins was decreased, and retinal structure and function were protected. These findings demonstrate that nanoceria can function as catalytic antioxidants in vivo and may be broad spectrum therapeutic agents for multiple types of ocular diseases.
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Cai X, Sezate SA, Seal S, McGinnis JF. WITHDRAWN: Sustained protection against photoreceptor degeneration in tubby mice by intravitreal injection of nanoceria. Biomaterials 2012:S0142-9612(12)00767-3. [PMID: 22871422 DOI: 10.1016/j.biomaterials.2012.06.102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 06/30/2012] [Indexed: 11/21/2022]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
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Affiliation(s)
- Xue Cai
- Department of Ophthalmology, Dean A. McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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