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Starr CR, Gorbatyuk MS. Posttranslational modifications of proteins in diseased retina. Front Cell Neurosci 2023; 17:1150220. [PMID: 37066080 PMCID: PMC10097899 DOI: 10.3389/fncel.2023.1150220] [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: 01/23/2023] [Accepted: 03/13/2023] [Indexed: 04/03/2023] Open
Abstract
Posttranslational modifications (PTMs) are known to constitute a key step in protein biosynthesis and in the regulation of protein functions. Recent breakthroughs in protein purification strategies and current proteome technologies make it possible to identify the proteomics of healthy and diseased retinas. Despite these advantages, the research field identifying sets of posttranslationally modified proteins (PTMomes) related to diseased retinas is significantly lagging, despite knowledge of the major retina PTMome being critical to drug development. In this review, we highlight current updates regarding the PTMomes in three retinal degenerative diseases-namely, diabetic retinopathy (DR), glaucoma, and retinitis pigmentosa (RP). A literature search reveals the necessity to expedite investigations into essential PTMomes in the diseased retina and validate their physiological roles. This knowledge would accelerate the development of treatments for retinal degenerative disorders and the prevention of blindness in affected populations.
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Affiliation(s)
| | - Marina S. Gorbatyuk
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
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2
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Balasubramanian H, Sankaran J, Pandey S, Goh CJH, Wohland T. The dependence of EGFR oligomerization on environment and structure: A camera-based N&B study. Biophys J 2022; 121:4452-4466. [PMID: 36335429 PMCID: PMC9748371 DOI: 10.1016/j.bpj.2022.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/30/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
Number and brightness (N&B) analysis is a fluorescence spectroscopy technique to quantify oligomerization of the mobile fraction of proteins. Accurate results, however, rely on a good knowledge of nonfluorescent states of the fluorescent labels, especially of fluorescent proteins, which are widely used in biology. Fluorescent proteins have been characterized for confocal, but not camera-based, N&B, which allows, in principle, faster measurements over larger areas. Here, we calibrate camera-based N&B implemented on a total internal reflection fluorescence microscope for various fluorescent proteins by determining their propensity to be fluorescent. We then apply camera-based N&B in live CHO-K1 cells to determine the oligomerization state of the epidermal growth factor receptor (EGFR), a transmembrane receptor tyrosine kinase that is a crucial regulator of cell proliferation and survival with implications in many cancers. EGFR oligomerization in resting cells and its regulation by the plasma membrane microenvironment are still under debate. Therefore, we investigate the effects of extrinsic factors, including membrane organization, cytoskeletal structure, and ligand stimulation, and intrinsic factors, including mutations in various EGFR domains, on the receptor's oligomerization. Our results demonstrate that EGFR oligomerization increases with removal of cholesterol or sphingolipids or the disruption of GM3-EGFR interactions, indicating raft association. However, oligomerization is not significantly influenced by the cytoskeleton. Mutations in either I706/V948 residues or E685/E687/E690 residues in the kinase and juxtamembrane domains, respectively, lead to a decrease in oligomerization, indicating their necessity for EGFR dimerization. Finally, EGFR phosphorylation is oligomerization dependent, involving the extracellular domain (550-580 residues). Coupled with biochemical investigations, camera-based N&B indicates that EGFR oligomerization and phosphorylation are the outcomes of several molecular interactions involving the lipid content and structure of the cell membrane and multiple residues in the kinase, juxtamembrane, and extracellular domains.
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Affiliation(s)
- Harikrushnan Balasubramanian
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Jagadish Sankaran
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Shambhavi Pandey
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Corinna Jie Hui Goh
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore; Department of Chemistry, National University of Singapore, Singapore, Singapore.
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3
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A multivesicular body-like organelle mediates stimulus-regulated trafficking of olfactory ciliary transduction proteins. Nat Commun 2022; 13:6889. [PMID: 36371422 PMCID: PMC9653401 DOI: 10.1038/s41467-022-34604-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 10/28/2022] [Indexed: 11/13/2022] Open
Abstract
Stimulus transduction in cilia of olfactory sensory neurons is mediated by odorant receptors, Gαolf, adenylate cyclase-3, cyclic nucleotide-gated and chloride ion channels. Mechanisms regulating trafficking and localization of these proteins in the dendrite are unknown. By lectin/immunofluorescence staining and in vivo correlative light-electron microscopy (CLEM), we identify a retinitis pigmentosa-2 (RP2), ESCRT-0 and synaptophysin-containing multivesicular organelle that is not part of generic recycling/degradative/exosome pathways. The organelle's intraluminal vesicles contain the olfactory transduction proteins except for Golf subunits Gγ13 and Gβ1. Instead, Gβ1 colocalizes with RP2 on the organelle's outer membrane. The organelle accumulates in response to stimulus deprivation, while odor stimuli or adenylate cyclase activation cause outer membrane disintegration, release of intraluminal vesicles, and RP2/Gβ1 translocation to the base of olfactory cilia. Together, these findings reveal the existence of a dendritic organelle that mediates both stimulus-regulated storage of olfactory ciliary transduction proteins and membrane-delimited sorting important for G protein heterotrimerization.
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4
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Retinitis pigmentosa 2 pathogenic mutants degrade through BAG6/HUWE1 complex. Exp Eye Res 2022; 220:109110. [DOI: 10.1016/j.exer.2022.109110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/30/2022] [Accepted: 05/08/2022] [Indexed: 11/21/2022]
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5
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Millette MA, Roy S, Salesse C. Farnesylation and lipid unsaturation are critical for the membrane binding of the C-terminal segment of G-Protein Receptor Kinase 1. Colloids Surf B Biointerfaces 2022; 211:112315. [PMID: 35026543 DOI: 10.1016/j.colsurfb.2021.112315] [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: 11/01/2021] [Revised: 12/15/2021] [Accepted: 12/30/2021] [Indexed: 10/19/2022]
Abstract
Many proteins are modified by the covalent addition of different types of lipids, such as myristoylation, palmitoylation and prenylation. Lipidation is expected to promote membrane association of proteins. Visual phototransduction involves many lipid-modified proteins. The G-Protein-coupled receptor of rod photoreceptors, rhodopsin, is inactivated by G-Protein-coupled Receptor Kinase 1 (GRK1). The C-terminus of GRK1 is farnesylated and its truncation has been shown to result in a very high decrease of its enzymatic activity, most likely because of the loss of its membrane localization. Little information is available on the membrane binding of GRK1 as well as of most prenylated proteins. Measurements of the membrane binding of the non-farnesylated and farnesylated C-terminal segment of GRK1 were thus performed using lipids typical of those found in rod outer segment disk membranes. Their random coil secondary structure was determined using circular dichroism and infrared spectroscopy. The non-farnesylated C-terminal segment of GRK1 has no surface activity. In contrast, the farnesylated C-terminal segment of GRK1 shows a particularly strong binding to lipid monolayers bearing at least one unsaturated fatty acyl chain. No binding is observed in the presence of monolayers of saturated phospholipids, in agreement with the low affinity of farnesylated Ras proteins for lipids in the liquid-ordered state. Altogether, these data demonstrate that the farnesyl group of the C-terminal segment of GRK1 is mandatory for its membrane binding, which is favored by particular lipids or lipid mixtures. This information will also be useful for the understanding of the membrane binding of other prenylated proteins.
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Affiliation(s)
- Marc-Antoine Millette
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Sarah Roy
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Christian Salesse
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
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6
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Patrizi C, Llado M, Benati D, Iodice C, Marrocco E, Guarascio R, Surace EM, Cheetham ME, Auricchio A, Recchia A. Allele-specific editing ameliorates dominant retinitis pigmentosa in a transgenic mouse model. Am J Hum Genet 2021; 108:295-308. [PMID: 33508235 PMCID: PMC7896132 DOI: 10.1016/j.ajhg.2021.01.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 01/08/2021] [Indexed: 12/11/2022] Open
Abstract
Retinitis pigmentosa (RP) is a group of progressive retinal degenerations of mostly monogenic inheritance, which cause blindness in about 1:3,500 individuals worldwide. Heterozygous variants in the rhodopsin (RHO) gene are the most common cause of autosomal dominant RP (adRP). Among these, missense variants at C-terminal proline 347, such as p.Pro347Ser, cause severe adRP recurrently in European affected individuals. Here, for the first time, we use CRISPR/Cas9 to selectively target the p.Pro347Ser variant while preserving the wild-type RHO allele in vitro and in a mouse model of adRP. Detailed in vitro, genomic, and biochemical characterization of the rhodopsin C-terminal editing demonstrates a safe downregulation of p.Pro347Ser expression leading to partial recovery of photoreceptor function in a transgenic mouse model treated with adeno-associated viral vectors. This study supports the safety and efficacy of CRISPR/Cas9-mediated allele-specific editing and paves the way for a permanent and precise correction of heterozygous variants in dominantly inherited retinal diseases.
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Affiliation(s)
- Clarissa Patrizi
- Centre for Regenerative Medicine, Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Manel Llado
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | - Daniela Benati
- Centre for Regenerative Medicine, Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Carolina Iodice
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | - Elena Marrocco
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | | | - Enrico M Surace
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy; Medical Genetics, Department of Translational Medicine, Federico II University, 80125 Naples, Italy
| | | | - Alberto Auricchio
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy; Medical Genetics, Department of Advanced Biomedicine, Federico II University, 80125 Naples, Italy.
| | - Alessandra Recchia
- Centre for Regenerative Medicine, Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy.
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7
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Fujinami K, Liu X, Ueno S, Mizota A, Shinoda K, Kuniyoshi K, Fujinami-Yokokawa Y, Yang L, Arno G, Pontikos N, Kameya S, Kominami T, Terasaki H, Sakuramoto H, Nakamura N, Kurihara T, Tsubota K, Miyake Y, Yoshiake K, Iwata T, Tsunoda K. RP2-associated retinal disorder in a Japanese cohort: Report of novel variants and a literature review, identifying a genotype-phenotype association. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:675-693. [PMID: 32875684 DOI: 10.1002/ajmg.c.31830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/28/2020] [Accepted: 07/28/2020] [Indexed: 01/10/2023]
Abstract
The retinitis pigmentosa 2 (RP2) gene is one of the causative genes for X-linked inherited retinal disorder. We characterized the clinical/genetic features of four patients with RP2-associated retinal disorder (RP2-RD) from four Japanese families in a nationwide cohort. A systematic review of RP2-RD in the Japanese population was also performed. All four patients were clinically diagnosed with retinitis pigmentosa (RP). The mean age at examination was 36.5 (10-47) years, and the mean visual acuity in the right/left eye was 1.40 (0.52-2.0)/1.10 (0.52-1.7) in the logarithm of the minimum angle of resolution unit, respectively. Three patients showed extensive retinal atrophy with macular involvement, and one had central retinal atrophy. Four RP2 variants were identified, including two novel missense (p.Ser6Phe, p.Leu189Pro) and two previously reported truncating variants (p.Arg120Ter, p.Glu269CysfsTer3). The phenotypes of two patients with truncating variants were more severe than the phenotypes of two patients with missense variants. A systematic review revealed additional 11 variants, including three missense and eight deleterious (null) variants, and a statistically significant association between phenotype severity and genotype severity was revealed. The clinical and genetic spectrum of RP2-RD was illustrated in the Japanese population, identifying the characteristic features of a severe form of RP with early macular involvement.
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Affiliation(s)
- Kaoru Fujinami
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
| | - Xiao Liu
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.,Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Shinji Ueno
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Atsushi Mizota
- Department of Ophthalmology, Teikyo University, Tokyo, Japan
| | - Kei Shinoda
- Department of Ophthalmology, Teikyo University, Tokyo, Japan.,Department of Ophthalmology, Saitama Medical University, Moroyama Campus, Saitama, Japan
| | - Kazuki Kuniyoshi
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
| | - Yu Fujinami-Yokokawa
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Department of Health Policy and Management, Keio University School of Medicine, Tokyo, Japan.,Division of Public Health, Yokokawa Clinic, Suita, Japan
| | - Lizhu Yang
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Gavin Arno
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK.,North East Thames Regional Genetics Service, UCL Great Ormond Street Institute of Child Health, NHS Foundation Trust, London, UK
| | - Nikolas Pontikos
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
| | - Shuhei Kameya
- Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Japan
| | - Taro Kominami
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroko Terasaki
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroyuki Sakuramoto
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
| | - Natsuko Nakamura
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Teikyo University, Tokyo, Japan.,Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Toshihide Kurihara
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Kazuo Tsubota
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Yozo Miyake
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Aichi Medical University, Nagakute, Japan.,Next vision, Kobe Eye Center, Kobe, Japan
| | - Kazutoshi Yoshiake
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Kazushige Tsunoda
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
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8
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Meinnel T, Dian C, Giglione C. Myristoylation, an Ancient Protein Modification Mirroring Eukaryogenesis and Evolution. Trends Biochem Sci 2020; 45:619-632. [PMID: 32305250 DOI: 10.1016/j.tibs.2020.03.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/02/2020] [Accepted: 03/12/2020] [Indexed: 12/18/2022]
Abstract
N-myristoylation (MYR) is a crucial fatty acylation catalyzed by N-myristoyltransferases (NMTs) that is likely to have appeared over 2 billion years ago. Proteome-wide approaches have now delivered an exhaustive list of substrates undergoing MYR across approximately 2% of any proteome, with constituents, several unexpected, associated with different membrane compartments. A set of <10 proteins conserved in eukaryotes probably represents the original set of N-myristoylated targets, marking major changes occurring throughout eukaryogenesis. Recent findings have revealed unexpected mechanisms and reactivity, suggesting competition with other acylations that are likely to influence cellular homeostasis and the steady state of the modification landscape. Here, we review recent advances in NMT catalysis, substrate specificity, and MYR proteomics, and discuss concepts regarding MYR during evolution.
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Affiliation(s)
- Thierry Meinnel
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
| | - Cyril Dian
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Carmela Giglione
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
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9
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Gupta A, Korte T, Herrmann A, Wohland T. Plasma membrane asymmetry of lipid organization: fluorescence lifetime microscopy and correlation spectroscopy analysis. J Lipid Res 2020; 61:252-266. [PMID: 31857388 PMCID: PMC6997606 DOI: 10.1194/jlr.d119000364] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 12/03/2019] [Indexed: 02/06/2023] Open
Abstract
A fundamental feature of the eukaryotic cell membrane is the asymmetric arrangement of lipids in its two leaflets. A cell invests significant energy to maintain this asymmetry and uses it to regulate important biological processes, such as apoptosis and vesiculation. The dynamic coupling of the inner or cytoplasmic and outer or exofacial leaflets is a challenging open question in membrane biology. Here, we combined fluorescence lifetime imaging microscopy (FLIM) with imaging total internal reflection fluorescence correlation spectroscopy (ITIR-FCS) to differentiate the dynamics and organization of the two leaflets of live mammalian cells. We characterized the biophysical properties of fluorescent analogs of phosphatidylcholine, sphingomyelin, and phosphatidylserine in the plasma membrane of two mammalian cell lines (CHO-K1 and RBL-2H3). Because of their specific transverse membrane distribution, these probes allowed leaflet-specific investigation of the plasma membrane. We compared the results of the two methods having different temporal and spatial resolution. Fluorescence lifetimes of fluorescent lipid analogs were in ranges characteristic for the liquid ordered phase in the outer leaflet and for the liquid disordered phase in the inner leaflet. The observation of a more fluid inner leaflet was supported by free diffusion in the inner leaflet, with high average diffusion coefficients. The liquid ordered phase in the outer leaflet was accompanied by slower diffusion and diffusion with intermittent transient trapping. Our results show that the combination of FLIM and ITIR-FCS with specific fluorescent lipid analogs is a powerful tool for investigating lateral and transbilayer characteristics of plasma membrane in live cell lines.
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Affiliation(s)
- Anjali Gupta
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences National University of Singapore, Singapore
| | - Thomas Korte
- Institute for Biology/Biophysics, Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Andreas Herrmann
- Institute for Biology/Biophysics, Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Thorsten Wohland
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences National University of Singapore, Singapore
- Department of Chemistry, National University of Singapore, Singapore
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10
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Roy K, Marin EP. Lipid Modifications in Cilia Biology. J Clin Med 2019; 8:jcm8070921. [PMID: 31252577 PMCID: PMC6678300 DOI: 10.3390/jcm8070921] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/22/2019] [Accepted: 06/24/2019] [Indexed: 12/17/2022] Open
Abstract
Cilia are specialized cellular structures with distinctive roles in various signaling cascades. Ciliary proteins need to be trafficked to the cilium to function properly; however, it is not completely understood how these proteins are delivered to their final localization. In this review, we will focus on how different lipid modifications are important in ciliary protein trafficking and, consequently, regulation of signaling pathways. Lipid modifications can play a variety of roles, including tethering proteins to the membrane, aiding trafficking through facilitating interactions with transporter proteins, and regulating protein stability and abundance. Future studies focusing on the role of lipid modifications of ciliary proteins will help our understanding of how cilia maintain specific protein pools strictly connected to their functions.
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Affiliation(s)
- Kasturi Roy
- Department of Internal Medicine, Section of Nephrology, Yale School of Medicine, PO Box 208029, New Haven, CT 06520-8029, USA.
| | - Ethan P Marin
- Department of Internal Medicine, Section of Nephrology, Yale School of Medicine, PO Box 208029, New Haven, CT 06520-8029, USA
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11
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Horner F, Wawrzynski J, MacLaren RE. Novel non-sense mutation in RP2 (c.843_844insT/p.Arg282fs) is associated with a severe phenotype of retinitis pigmentosa without evidence of primary retinal pigment epithelium involvement. BMJ Case Rep 2019; 12:12/5/e224451. [PMID: 31079036 DOI: 10.1136/bcr-2018-224451] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Retinitis pigmentosa (RP) relates to a heterogeneous group of rod-cone dystrophies of varying genetic aetiology. There is currently great interest in gene replacement therapy. Phenotyping is of particular importance because some RP genes are expressed ubiquitously and it is critically important to understand which retinal layer is primarily affected. RP2 is increasingly diagnosed in patients suffering from X-linked RP, which causes outer retinal degeneration. We present a case of a previously unreported null mutation in RP2 associated with severe RP. Loss of the retinal pigment epithelium (RPE) was noted in the central macula but not around the disc or peripherally. There was therefore no evidence of independent degeneration of the RPE. Hence despite expression in all retinal cells, RP2 deficiency does not appear to be pathogenic to the RPE. This observation may be helpful in considering the promoter and route of delivery of adeno-associated viral gene therapy vectors encoding RP2.
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Affiliation(s)
- Faye Horner
- Ophthalmology, Department of Clinical Neurosciences,John Radcliffe Hospital, Oxford, UK
| | - James Wawrzynski
- Ophthalmology, Department of Clinical Neurosciences,John Radcliffe Hospital, Oxford, UK
| | - Robert E MacLaren
- Ophthalmology, Department of Clinical Neurosciences,John Radcliffe Hospital, Oxford, UK
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12
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A novel RP2 missense mutation Q158P identified in an X-linked retinitis pigmentosa family impaired RP2 protein stability. Gene 2019; 707:86-92. [PMID: 31071385 DOI: 10.1016/j.gene.2019.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 04/19/2019] [Accepted: 05/03/2019] [Indexed: 12/23/2022]
Abstract
Retinitis pigmentosa (RP) is the most common form of inherited retinal degenerative diseases. X-linked RP accounts for nearly 15% of all RP cases. In this study, we identified a novel RP2 missense mutation Q158P in a Chinese XLRP family. The RP2 Q158P mutation located in the RP2 TBCC domain and obviously destabilized RP2 protein in ARPE-19 cells. The proteasome inhibitor MG132 could restore the RP2 Q158P protein levels. Meanwhile, lower doses of bortezomib and carfilzomib, another two proteasome inhibitors that have been approved in multiple myeloma clinical therapy, also could rescue the RP2 Q158P protein levels. The ubiquitination of RP2 Q158P protein obviously increased when compared with wild type RP2 protein. Our findings broadened the spectrum of RP2 mutations and may contribute a better understanding of the molecular mechanism of XLRP.
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13
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Harmer J, Towers K, Addison M, Vaughan S, Ginger ML, McKean PG. A centriolar FGR1 oncogene partner-like protein required for paraflagellar rod assembly, but not axoneme assembly in African trypanosomes. Open Biol 2019; 8:rsob.170218. [PMID: 30045883 PMCID: PMC6070722 DOI: 10.1098/rsob.170218] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 06/21/2018] [Indexed: 01/21/2023] Open
Abstract
Proteins of the FGR1 oncogene partner (or FOP) family are found at microtubule organizing centres (MTOCs) including, in flagellate eukaryotes, the centriole or flagellar basal body from which the axoneme extends. We report conservation of FOP family proteins, TbFOPL and TbOFD1, in the evolutionarily divergent sleeping sickness parasite Trypanosoma brucei, showing (in contrast with mammalian cells, where FOP is essential for flagellum assembly) depletion of a trypanosome FOP homologue, TbFOPL, affects neither axoneme nor flagellum elongation. Instead, TbFOPL depletion causes catastrophic failure in assembly of a lineage-specific, extra-axonemal structure, the paraflagellar rod (PFR). That depletion of centriolar TbFOPL causes failure in PFR assembly is surprising because PFR nucleation commences approximately 2 µm distal from the basal body. When over-expressed with a C-terminal myc-epitope, TbFOPL was also observed at mitotic spindle poles. Little is known about bi-polar spindle assembly during closed trypanosome mitosis, but indication of a possible additional MTOC function for TbFOPL parallels MTOC localization of FOP-like protein TONNEAU1 in acentriolar plants. More generally, our functional analysis of TbFOPL emphasizes significant differences in evolutionary cell biology trajectories of FOP-family proteins. We discuss how at the molecular level FOP homologues may contribute to flagellum assembly and function in diverse flagellates.
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Affiliation(s)
- Jane Harmer
- Faculty of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, UK
| | - Katie Towers
- Department of Biological and Medical Sciences, Faculty of Health and Life Science, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, UK
| | - Max Addison
- Faculty of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, UK
| | - Sue Vaughan
- Department of Biological and Medical Sciences, Faculty of Health and Life Science, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, UK
| | - Michael L Ginger
- Department of Biological and Geographical Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK
| | - Paul G McKean
- Faculty of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, UK
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14
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Kumeta M, Panina Y, Yamazaki H, Takeyasu K, Yoshimura SH. N-terminal dual lipidation-coupled molecular targeting into the primary cilium. Genes Cells 2018; 23:715-723. [PMID: 29900630 DOI: 10.1111/gtc.12603] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 05/07/2018] [Accepted: 05/14/2018] [Indexed: 01/24/2023]
Abstract
The primary cilium functions as an "antenna" for cell signaling, studded with characteristic transmembrane receptors and soluble protein factors, raised above the cell surface. In contrast to the transmembrane proteins, targeting mechanisms of nontransmembrane ciliary proteins are poorly understood. We focused on a pathogenic mutation that abolishes ciliary localization of retinitis pigmentosa 2 protein and revealed a dual acylation-dependent ciliary targeting pathway. Short N-terminal sequences which contain myristoylation and palmitoylation sites are sufficient to target a marker protein into the cilium in a palmitoylation-dependent manner. A Golgi-localized palmitoyltransferase DHHC-21 was identified as the key enzyme controlling this targeting pathway. Rapid turnover of the targeted protein was ensured by cholesterol-dependent membrane fluidity, which balances highly and less-mobile populations of the molecules within the cilium. This targeting signal was found in a set of signal transduction molecules, suggesting a general role of this pathway in proper ciliary organization, and dysfunction in ciliary disorders.
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Affiliation(s)
- Masahiro Kumeta
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Yulia Panina
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Quantitative Biology Center (QBiC), Osaka, Japan
| | - Hiroya Yamazaki
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Kunio Takeyasu
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Institute of Biotechnology, National Taiwan University, Taipei, Taiwan
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15
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Lyraki R, Lokaj M, Soares DC, Little A, Vermeren M, Marsh JA, Wittinghofer A, Hurd T. Characterization of a novel RP2-OSTF1 interaction and its implication for actin remodelling. J Cell Sci 2018; 131:jcs.211748. [PMID: 29361551 DOI: 10.1242/jcs.211748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/21/2017] [Indexed: 11/20/2022] Open
Abstract
Retinitis pigmentosa 2 (RP2) is the causative gene for a form of X-linked retinal degeneration. RP2 was previously shown to have GTPase-activating protein (GAP) activity towards the small GTPase ARL3 via its N-terminus, but the function of the C-terminus remains elusive. Here, we report a novel interaction between RP2 and osteoclast-stimulating factor 1 (OSTF1), an intracellular protein that indirectly enhances osteoclast formation and activity and is a negative regulator of cell motility. Moreover, this interaction is abolished by a human pathogenic mutation in RP2. We utilized a structure-based approach to pinpoint the binding interface to a strictly conserved cluster of residues on the surface of RP2 that spans both the C- and N-terminal domains of the protein, and which is structurally distinct from the ARL3-binding site. In addition, we show that RP2 is a positive regulator of cell motility in vitro, recruiting OSTF1 to the cell membrane and preventing its interaction with the migration regulator Myo1E.
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Affiliation(s)
- Rodanthi Lyraki
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
| | - Mandy Lokaj
- Structural Biology Group, Max-Planck Institut für Molekulare Physiologie, Abteilung Strukturelle Biologie, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
| | - Dinesh C Soares
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
| | - Abigail Little
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
| | - Matthieu Vermeren
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK.,MRC Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
| | - Joseph A Marsh
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
| | - Alfred Wittinghofer
- Structural Biology Group, Max-Planck Institut für Molekulare Physiologie, Abteilung Strukturelle Biologie, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
| | - Toby Hurd
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
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16
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The secret life of kinases: insights into non-catalytic signalling functions from pseudokinases. Biochem Soc Trans 2017; 45:665-681. [PMID: 28620028 DOI: 10.1042/bst20160331] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 03/08/2017] [Accepted: 03/09/2017] [Indexed: 12/31/2022]
Abstract
Over the past decade, our understanding of the mechanisms by which pseudokinases, which comprise ∼10% of the human and mouse kinomes, mediate signal transduction has advanced rapidly with increasing structural, biochemical, cellular and genetic studies. Pseudokinases are the catalytically defective counterparts of conventional, active protein kinases and have been attributed functions as protein interaction domains acting variously as allosteric modulators of conventional protein kinases and other enzymes, as regulators of protein trafficking or localisation, as hubs to nucleate assembly of signalling complexes, and as transmembrane effectors of such functions. Here, by categorising mammalian pseudokinases based on their known functions, we illustrate the mechanistic diversity among these proteins, which can be viewed as a window into understanding the non-catalytic functions that can be exerted by conventional protein kinases.
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17
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Disease mechanisms of X-linked retinitis pigmentosa due to RP2 and RPGR mutations. Biochem Soc Trans 2017; 44:1235-1244. [PMID: 27911705 DOI: 10.1042/bst20160148] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 08/16/2016] [Accepted: 08/18/2016] [Indexed: 01/24/2023]
Abstract
Photoreceptor degeneration is the prominent characteristic of retinitis pigmentosa (RP), a heterogeneous group of inherited retinal dystrophies resulting in blindness. Although abnormalities in many pathways can cause photoreceptor degeneration, one of the most important causes is defective protein transport through the connecting cilium, the structure that connects the biosynthetic inner segment with the photosensitive outer segment of the photoreceptors. The majority of patients with X-linked RP have mutations in the retinitis pigmentosa GTPase regulator (RPGR) or RP2 genes, the protein products of which are both components of the connecting cilium and associated with distinct mechanisms of protein delivery to the outer segment. RP2 and RPGR proteins are associated with severe diseases ranging from classic RP to atypical forms. In this short review, we will summarise current knowledge generated by experimental studies and knockout animal models, compare and discuss the prominent hypotheses about the two proteins' functions in retinal cell biology.
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18
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Schwarz N, Lane A, Jovanovic K, Parfitt DA, Aguila M, Thompson CL, da Cruz L, Coffey PJ, Chapple JP, Hardcastle AJ, Cheetham ME. Arl3 and RP2 regulate the trafficking of ciliary tip kinesins. Hum Mol Genet 2017; 26:2480-2492. [PMID: 28444310 PMCID: PMC5808637 DOI: 10.1093/hmg/ddx143] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/07/2017] [Accepted: 04/11/2017] [Indexed: 11/14/2022] Open
Abstract
Ciliary trafficking defects are the underlying cause of many ciliopathies, including Retinitis Pigmentosa (RP). Anterograde intraflagellar transport (IFT) is mediated by kinesin motor proteins; however, the function of the homodimeric Kif17 motor in cilia is poorly understood, whereas Kif7 is known to play an important role in stabilizing cilia tips. Here we identified the ciliary tip kinesins Kif7 and Kif17 as novel interaction partners of the small GTPase Arl3 and its regulatory GTPase activating protein (GAP) Retinitis Pigmentosa 2 (RP2). We show that Arl3 and RP2 mediate the localization of GFP-Kif17 to the cilia tip and competitive binding of RP2 and Arl3 with Kif17 complexes. RP2 and Arl3 also interact with another ciliary tip kinesin, Kif7, which is a conserved regulator of Hedgehog (Hh) signaling. siRNA-mediated loss of RP2 or Arl3 reduced the level of Kif7 at the cilia tip. This was further validated by reduced levels of Kif7 at cilia tips detected in fibroblasts and induced pluripotent stem cell (iPSC) 3D optic cups derived from a patient carrying an RP2 nonsense mutation c.519C > T (p.R120X), which lack detectable RP2 protein. Translational read-through inducing drugs (TRIDs), such as PTC124, were able to restore Kif7 levels at the ciliary tip of RP2 null cells. Collectively, our findings suggest that RP2 and Arl3 regulate the trafficking of specific kinesins to cilia tips and provide additional evidence that TRIDs could be clinically beneficial for patients with this retinal degeneration.
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Affiliation(s)
- Nele Schwarz
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - Amelia Lane
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | | | | | | | - Clare L. Thompson
- Institute of Bioengineering, School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
| | - Lyndon da Cruz
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Moorfields Eye Hospital, London EC1V 2PD, UK
| | | | - J. Paul Chapple
- William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
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19
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Boisselier É, Demers É, Cantin L, Salesse C. How to gather useful and valuable information from protein binding measurements using Langmuir lipid monolayers. Adv Colloid Interface Sci 2017; 243:60-76. [PMID: 28372794 DOI: 10.1016/j.cis.2017.03.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 03/14/2017] [Accepted: 03/15/2017] [Indexed: 12/22/2022]
Abstract
This review presents data on the influence of various experimental parameters on the binding of proteins onto Langmuir lipid monolayers. The users of the Langmuir methodology are often unaware of the importance of choosing appropriate experimental conditions to validate the data acquired with this method. The protein Retinitis pigmentosa 2 (RP2) has been used throughout this review to illustrate the influence of these experimental parameters on the data gathered with Langmuir monolayers. The methods detailed in this review include the determination of protein binding parameters from the measurement of adsorption isotherms, infrared spectra of the protein in solution and in monolayers, ellipsometric isotherms and fluorescence micrographs.
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Affiliation(s)
- Élodie Boisselier
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
| | - Éric Demers
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Line Cantin
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Christian Salesse
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
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20
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Liu F, Qin Y, Yu S, Soares DC, Yang L, Weng J, Li C, Gao M, Lu Z, Hu X, Liu X, Jiang T, Liu JY, Shu X, Tang Z, Liu M. Pathogenic mutations in retinitis pigmentosa 2 predominantly result in loss of RP2 protein stability in humans and zebrafish. J Biol Chem 2017; 292:6225-6239. [PMID: 28209709 PMCID: PMC5391753 DOI: 10.1074/jbc.m116.760314] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 02/14/2017] [Indexed: 12/20/2022] Open
Abstract
Mutations in retinitis pigmentosa 2 (RP2) account for 10-20% of X-linked retinitis pigmentosa (RP) cases. The encoded RP2 protein is implicated in ciliary trafficking of myristoylated and prenylated proteins in photoreceptor cells. To date >70 mutations in RP2 have been identified. How these mutations disrupt the function of RP2 is not fully understood. Here we report a novel in-frame 12-bp deletion (c.357_368del, p.Pro120_Gly123del) in zebrafish rp2 The mutant zebrafish shows reduced rod phototransduction proteins and progressive retinal degeneration. Interestingly, the protein level of mutant Rp2 is almost undetectable, whereas its mRNA level is near normal, indicating a possible post-translational effect of the mutation. Consistent with this hypothesis, the equivalent 12-bp deletion in human RP2 markedly impairs RP2 protein stability and reduces its protein level. Furthermore, we found that a majority of the RP2 pathogenic mutations (including missense, single-residue deletion, and C-terminal truncation mutations) severely destabilize the RP2 protein. The destabilized RP2 mutant proteins are degraded via the proteasome pathway, resulting in dramatically decreased protein levels. The remaining non-destabilizing mutations T87I, R118H/R118G/R118L/R118C, E138G, and R211H/R211L are suggested to impair the interaction between RP2 and its protein partners (such as ARL3) or with as yet unknown partners. By utilizing a combination of in silico, in vitro, and in vivo approaches, our work comprehensively indicates that loss of RP2 protein structural stability is the predominating pathogenic consequence for most RP2 mutations. Our study also reveals a role of the C-terminal domain of RP2 in maintaining the overall protein stability.
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Affiliation(s)
- Fei Liu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Yayun Qin
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Shanshan Yu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Dinesh C Soares
- MRC Human Genetics Unit/Centre for Genomic and Experimental Medicine, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom, and
| | - Lifang Yang
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Jun Weng
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Chang Li
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Meng Gao
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Zhaojing Lu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Xuebin Hu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Xiliang Liu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Tao Jiang
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Jing Yu Liu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Xinhua Shu
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, United Kingdom
| | - Zhaohui Tang
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Mugen Liu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China,
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21
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Analysis of RP2 and RPGR Mutations in Five X-Linked Chinese Families with Retinitis Pigmentosa. Sci Rep 2017; 7:44465. [PMID: 28294154 PMCID: PMC5353642 DOI: 10.1038/srep44465] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/08/2017] [Indexed: 11/08/2022] Open
Abstract
Mutations in RP2 and RPGR genes are responsible for the X-linked retinitis pigmentosa (XLRP). In this study, we analyzed the RP2 and RPGR gene mutations in five Han Chinese families with XLRP. An approximately 17Kb large deletion including the exon 4 and exon 5 of RP2 gene was found in an XLRP family. In addition, four frameshift mutations including three novel mutations of c.1059 + 1 G > T, c.2002dupC and c.2236_2237del CT, as well as a previously reported mutation of c.2899delG were detected in the RPGR gene in the other four families. Our study further expands the mutation spectrum of RP2 and RPGR, and will be helpful for further study molecular pathogenesis of XLRP.
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22
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Huang S, Lim SY, Gupta A, Bag N, Wohland T. Plasma membrane organization and dynamics is probe and cell line dependent. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:1483-1492. [PMID: 27998689 DOI: 10.1016/j.bbamem.2016.12.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/03/2016] [Accepted: 12/08/2016] [Indexed: 01/01/2023]
Abstract
The action and interaction of membrane receptor proteins take place within the plasma membrane. The plasma membrane, however, is not a passive matrix. It rather takes an active role and regulates receptor distribution and function by its composition and the interaction of its lipid components with embedded and surrounding proteins. Furthermore, it is not a homogenous fluid but contains lipid and protein domains of various sizes and characteristic lifetimes which are important in regulating receptor function and signaling. The precise lateral organization of the plasma membrane, the differences between the inner and outer leaflet, and the influence of the cytoskeleton are still debated. Furthermore, there is a lack of comparisons of the organization and dynamics of the plasma membrane of different cell types. Therefore, we used four different specific membrane markers to test the lateral organization, the differences between the inner and outer membrane leaflet, and the influence of the cytoskeleton of up to five different cell lines, including Chinese hamster ovary (CHO-K1), Human cervical carcinoma (HeLa), neuroblastoma (SH-SY5Y), fibroblast (WI-38) and rat basophilic leukemia (RBL-2H3) cells by Imaging Total Internal Reflection (ITIR)-Fluorescence Correlation Spectroscopy (FCS). We measure diffusion in the temperature range of 298-310K to measure the Arrhenius activation energy (EArr) of diffusion and apply the FCS diffusion law to obtain information on the spatial organization of the probe molecules on the various cell membranes. Our results show clear differences of the FCS diffusion law and EArr for the different probes in dependence of their localization. These differences are similar in the outer and inner leaflet of the membrane. However, these values can differ significantly between different cell lines raising the question how molecular plasma membrane events measured in different cell lines can be compared. This article is part of a Special Issue entitled: Interactions between membrane receptors in cellular membranes edited by Kalina Hristova.
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Affiliation(s)
- Shuangru Huang
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore
| | - Shi Ying Lim
- NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore; Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore
| | - Anjali Gupta
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore
| | - Nirmalya Bag
- NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore; Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore; Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore.
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23
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Li L, Rao KN, Zheng-Le Y, Hurd TW, Lillo C, Khanna H. Loss of retinitis pigmentosa 2 (RP2) protein affects cone photoreceptor sensory cilium elongation in mice. Cytoskeleton (Hoboken) 2015; 72:447-54. [PMID: 26383048 DOI: 10.1002/cm.21255] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 09/11/2015] [Accepted: 09/15/2015] [Indexed: 02/03/2023]
Abstract
Degeneration of photoreceptors (rods and cones) results in blindness. As we rely almost entirely on our daytime vision mediated by the cones, it is the loss of these photoreceptors that results in legal blindness and poor quality of life. Cone dysfunction is usually observed due to two mechanisms: noncell-autonomous due to the secondary effect of rod death if the causative gene is specifically expressed in rods and cell autonomous, if the mutation is in a cone-specific gene. However, it is difficult to dissect cone autonomous effect of mutations in the genes that are expressed in both rods and cones. Here we report a property of murine cone photoreceptors, which is a cone-autonomous effect of the genetic perturbation of the retinitis pigmentosa 2 (Rp2) gene mutated in human X-linked RP. Constitutive loss of Rp2 results in abnormal extension of the cone outer segment (COS). This effect is phenocopied when the Rp2 gene is ablated specifically in cones but not when ablated in rods. Furthermore, the elongated COS exhibits abnormal ultrastructure with disorganized lamellae. Additionally, elongation of both the outer segment membrane and the microtubule cytoskeleton was observed in the absence of RP2. Taken together, our studies identify a cone morphological defect in retinal degeneration due to ablation of RP2 and will assist in understanding cone-autonomous responses during disease and develop targeted therapies.
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Affiliation(s)
- Linjing Li
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Kollu Nageswara Rao
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Yun Zheng-Le
- Department of Medicine, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma
| | | | - Concepción Lillo
- Institute of Neurosciences of Castilla Y León-INCyL, Institute of Biomedical Research of Salamanca-IBSAL, Cell Biology and Pathology, University of Salamanca, Salamanca, Spain
| | - Hemant Khanna
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts
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24
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Sherman WA, Kuchibhatla DB, Limviphuvadh V, Maurer-Stroh S, Eisenhaber B, Eisenhaber F. HPMV: human protein mutation viewer - relating sequence mutations to protein sequence architecture and function changes. J Bioinform Comput Biol 2015; 13:1550028. [PMID: 26503432 DOI: 10.1142/s0219720015500286] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Next-generation sequencing advances are rapidly expanding the number of human mutations to be analyzed for causative roles in genetic disorders. Our Human Protein Mutation Viewer (HPMV) is intended to explore the biomolecular mechanistic significance of non-synonymous human mutations in protein-coding genomic regions. The tool helps to assess whether protein mutations affect the occurrence of sequence-architectural features (globular domains, targeting signals, post-translational modification sites, etc.). As input, HPMV accepts protein mutations - as UniProt accessions with mutations (e.g. HGVS nomenclature), genome coordinates, or FASTA sequences. As output, HPMV provides an interactive cartoon showing the mutations in relation to elements of the sequence architecture. A large variety of protein sequence architectural features were selected for their particular relevance to mutation interpretation. Clicking a sequence feature in the cartoon expands a tree view of additional information including multiple sequence alignments of conserved domains and a simple 3D viewer mapping the mutation to known PDB structures, if available. The cartoon is also correlated with a multiple sequence alignment of similar sequences from other organisms. In cases where a mutation is likely to have a straightforward interpretation (e.g. a point mutation disrupting a well-understood targeting signal), this interpretation is suggested. The interactive cartoon can be downloaded as standalone viewer in Java jar format to be saved and viewed later with only a standard Java runtime environment. The HPMV website is: http://hpmv.bii.a-star.edu.sg/ .
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Affiliation(s)
- Westley Arthur Sherman
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street #07-01, Matrix, Singapore 138671, Singapore
| | - Durga Bhavani Kuchibhatla
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street #07-01, Matrix, Singapore 138671, Singapore
| | - Vachiranee Limviphuvadh
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street #07-01, Matrix, Singapore 138671, Singapore
| | - Sebastian Maurer-Stroh
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street #07-01, Matrix, Singapore 138671, Singapore
- School of Biological Sciences (SBS), Nanyang Technological University (NTU), 60 Nanyang Drive, Singapore 637551, Singapore
| | - Birgit Eisenhaber
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street #07-01, Matrix, Singapore 138671, Singapore
| | - Frank Eisenhaber
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street #07-01, Matrix, Singapore 138671, Singapore
- Department of Biological Sciences (DBS), National University of Singapore (NUS), 8 Medical Drive 4, Singapore 117597, Singapore
- School of Computer Engineering (SCE), Nanyang Technological University (NTU), 50 Nanyang Drive, Singapore 637553, Singapore
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Mookherjee S, Hiriyanna S, Kaneshiro K, Li L, Li Y, Li W, Qian H, Li T, Khanna H, Colosi P, Swaroop A, Wu Z. Long-term rescue of cone photoreceptor degeneration in retinitis pigmentosa 2 (RP2)-knockout mice by gene replacement therapy. Hum Mol Genet 2015; 24:6446-58. [PMID: 26358772 DOI: 10.1093/hmg/ddv354] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/01/2015] [Indexed: 11/14/2022] Open
Abstract
Retinal neurodegenerative diseases are especially attractive targets for gene replacement therapy, which appears to be clinically effective for several monogenic diseases. X-linked forms of retinitis pigmentosa (XLRP) are relatively severe blinding disorders, resulting from progressive photoreceptor dysfunction primarily caused by mutations in RPGR or RP2 gene. With a goal to develop gene therapy for the XLRP-RP2 disease, we first performed detailed characterization of the Rp2-knockout (Rp2-KO) mice and observed early-onset cone dysfunction, which was followed by progressive cone degeneration, mimicking cone vision impairment in XLRP patients. The mice also exhibited distinct and significantly delayed falling phase of photopic b-wave of electroretinogram (ERG). Concurrently, we generated a self-complementary adeno-associated viral (AAV) vector carrying human RP2-coding sequence and demonstrated its ability to mediate stable RP2 protein expression in mouse photoreceptors. A long-term efficacy study was then conducted in Rp2-KO mice following AAV-RP2 vector administration. Preservation of cone function was achieved with a wide dose range over 18-month duration, as evidenced by photopic ERG and optomotor tests. The slower b-wave kinetics was also completely restored. Morphologically, the treatment preserved cone viability, corrected mis-trafficking of M-cone opsin and restored cone PDE6 expression. The therapeutic effect was achieved even in mice that received treatment at an advanced disease stage. The highest AAV-RP2 dose group demonstrated retinal toxicity, highlighting the importance of careful vector dosing in designing future human trials. The wide range of effective dose, a broad treatment window and long-lasting therapeutic effects should make the RP2 gene therapy attractive for clinical development.
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Affiliation(s)
| | - Suja Hiriyanna
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Kayleigh Kaneshiro
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Linjing Li
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Yichao Li
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Wei Li
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Haohua Qian
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Tiansen Li
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Hemant Khanna
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Peter Colosi
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Anand Swaroop
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Zhijian Wu
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA and
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Desvignes T, Nguyen T, Chesnel F, Bouleau A, Fauvel C, Bobe J. X-Linked Retinitis Pigmentosa 2 Is a Novel Maternal-Effect Gene Required for Left-Right Asymmetry in Zebrafish. Biol Reprod 2015; 93:42. [PMID: 26134862 DOI: 10.1095/biolreprod.115.130575] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 06/10/2015] [Indexed: 01/05/2023] Open
Abstract
Retinitis pigmentosa 2 (RP2) gene is responsible for up to 20% of X-linked retinitis pigmentosa, a severe heterogeneous genetic disorder resulting in progressive retinal degeneration in humans. In vertebrates, several bodies of evidence have clearly established the role of Rp2 protein in cilia genesis and/or function. Unexpectedly, some observations in zebrafish have suggested the oocyte-predominant expression of the rp2 gene, a typical feature of maternal-effect genes. In the present study, we investigate the maternal inheritance of rp2 gene products in zebrafish eggs in order to address whether rp2 could be a novel maternal-effect gene required for normal development. Although both rp2 mRNA and corresponding protein are expressed during oogenesis, rp2 mRNA is maternally inherited, in contrast to Rp2 protein. A knockdown of the protein transcribed from both rp2 maternal and zygotic mRNA results in delayed epiboly and severe developmental defects, including eye malformations, that were not observed when only the protein from zygotic origin was knocked down. Moreover, the knockdown of maternal and zygotic Rp2 revealed a high incidence of left-right asymmetry establishment defects compared to only zygotic knockdown. Here we show that rp2 is a novel maternal-effect gene exclusively expressed in oocytes within the zebrafish ovary and demonstrate that maternal rp2 mRNA is essential for successful embryonic development and thus contributes to egg developmental competence. Our observations also reveal that Rp2 protein translated from maternal mRNA is important to allow normal heart loop formation, thus providing evidence of a direct maternal contribution to left-right asymmetry establishment.
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Affiliation(s)
- Thomas Desvignes
- INRA, UR1037 Fish Physiology and Genomics, Campus de Beaulieu, Rennes, France IFREMER, LALR, Palavas Les Flots, France
| | - Thaovi Nguyen
- INRA, UR1037 Fish Physiology and Genomics, Campus de Beaulieu, Rennes, France
| | | | - Aurélien Bouleau
- INRA, UR1037 Fish Physiology and Genomics, Campus de Beaulieu, Rennes, France IFREMER, LALR, Palavas Les Flots, France
| | | | - Julien Bobe
- INRA, UR1037 Fish Physiology and Genomics, Campus de Beaulieu, Rennes, France
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Gonçalves J, Tavares A, Carvalhal S, Soares H. Revisiting the tubulin folding pathway: new roles in centrosomes and cilia. Biomol Concepts 2015; 1:423-34. [PMID: 25962015 DOI: 10.1515/bmc.2010.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Centrosomes and cilia are critical eukaryotic organelles which have been in the spotlight in recent years given their implication in a myriad of cellular and developmental processes. Despite their recognized importance and intense study, there are still many open questions about their biogenesis and function. In the present article, we review the existing data concerning members of the tubulin folding pathway and related proteins, which have been identified at centrosomes and cilia and were shown to have unexpected roles in these structures.
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Demers É, Boisselier É, Horchani H, Blaudez D, Calvez P, Cantin L, Belley N, Champagne S, Desbat B, Salesse C. Lipid Selectivity, Orientation, and Extent of Membrane Binding of Nonacylated RP2. Biochemistry 2015; 54:2560-70. [DOI: 10.1021/bi501517r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Éric Demers
- CUO-Recherche,
Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec
and Département d’ophtalmologie, Faculté de médecine,
and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Élodie Boisselier
- CUO-Recherche,
Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec
and Département d’ophtalmologie, Faculté de médecine,
and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Habib Horchani
- CUO-Recherche,
Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec
and Département d’ophtalmologie, Faculté de médecine,
and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Daniel Blaudez
- CBMN-UMR
5248 CNRS, Université de Bordeaux, IPB, Allée Geoffroy
Saint Hilaire, 33600 Pessac, France
| | - Philippe Calvez
- CUO-Recherche,
Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec
and Département d’ophtalmologie, Faculté de médecine,
and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Line Cantin
- CUO-Recherche,
Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec
and Département d’ophtalmologie, Faculté de médecine,
and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Nicolas Belley
- CUO-Recherche,
Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec
and Département d’ophtalmologie, Faculté de médecine,
and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Sophie Champagne
- CUO-Recherche,
Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec
and Département d’ophtalmologie, Faculté de médecine,
and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Bernard Desbat
- CBMN-UMR
5248 CNRS, Université de Bordeaux, IPB, Allée Geoffroy
Saint Hilaire, 33600 Pessac, France
| | - Christian Salesse
- CUO-Recherche,
Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec
and Département d’ophtalmologie, Faculté de médecine,
and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
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Schwarz N, Carr AJ, Lane A, Moeller F, Chen LL, Aguilà M, Nommiste B, Muthiah MN, Kanuga N, Wolfrum U, Nagel-Wolfrum K, da Cruz L, Coffey PJ, Cheetham ME, Hardcastle AJ. Translational read-through of the RP2 Arg120stop mutation in patient iPSC-derived retinal pigment epithelium cells. Hum Mol Genet 2015; 24:972-86. [PMID: 25292197 PMCID: PMC4986549 DOI: 10.1093/hmg/ddu509] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 09/29/2014] [Indexed: 01/08/2023] Open
Abstract
Mutations in the RP2 gene lead to a severe form of X-linked retinitis pigmentosa. RP2 patients frequently present with nonsense mutations and no treatments are currently available to restore RP2 function. In this study, we reprogrammed fibroblasts from an RP2 patient carrying the nonsense mutation c.519C>T (p.R120X) into induced pluripotent stem cells (iPSC), and differentiated these cells into retinal pigment epithelial cells (RPE) to study the mechanisms of disease and test potential therapies. RP2 protein was undetectable in the RP2 R120X patient cells, suggesting a disease mechanism caused by complete lack of RP2 protein. The RP2 patient fibroblasts and iPSC-derived RPE cells showed phenotypic defects in IFT20 localization, Golgi cohesion and Gβ1 trafficking. These phenotypes were corrected by over-expressing GFP-tagged RP2. Using the translational read-through inducing drugs (TRIDs) G418 and PTC124 (Ataluren), we were able to restore up to 20% of endogenous, full-length RP2 protein in R120X cells. This level of restored RP2 was sufficient to reverse the cellular phenotypic defects observed in both the R120X patient fibroblasts and iPSC-RPE cells. This is the first proof-of-concept study to demonstrate successful read-through and restoration of RP2 function for the R120X nonsense mutation. The ability of the restored RP2 protein level to reverse the observed cellular phenotypes in cells lacking RP2 indicates that translational read-through could be clinically beneficial for patients.
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Affiliation(s)
- Nele Schwarz
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Amanda-Jayne Carr
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Amelia Lane
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Fabian Moeller
- Johannes Gutenberg-University Muellerweg 6, 55099 Mainz, Germany and
| | - Li Li Chen
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Mònica Aguilà
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Britta Nommiste
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Manickam N Muthiah
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK, Moorfields Eye Hospital, 162 City Road, London EC1V 2PD, UK
| | - Naheed Kanuga
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Uwe Wolfrum
- Johannes Gutenberg-University Muellerweg 6, 55099 Mainz, Germany and
| | | | - Lyndon da Cruz
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK, Moorfields Eye Hospital, 162 City Road, London EC1V 2PD, UK
| | - Peter J Coffey
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
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Baehr W. Membrane protein transport in photoreceptors: the function of PDEδ: the Proctor lecture. Invest Ophthalmol Vis Sci 2014; 55:8653-66. [PMID: 25550383 DOI: 10.1167/iovs.14-16066] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
This lecture details the elucidation of cGMP phosphodiesterase (PDEδ), discovered 25 years ago by Joe Beavo at the University of Washington. PDEδ, once identified as a fourth PDE6 subunit, is now regarded as a promiscuous prenyl-binding protein and important chaperone of prenylated small G proteins of the Ras superfamily and prenylated proteins of phototransduction. Alfred Wittinghofer's group in Germany showed that PDEδ forms an immunoglobulin-like β-sandwich fold that is closely related in structure to other lipid-binding proteins, for example, Uncoordinated 119 (UNC119) and RhoGDI. His group cocrystallized PDEδ with ARL (Arf-like) 2(GTP), and later with farnesylated Rheb (ras homolog expressed in brain). PDEδ specifically accommodates farnesyl and geranylgeranyl moieties in the absence of bound protein. Germline deletion of the Pde6d gene encoding PDEδ impeded transport of rhodopsin kinase (GRK1) and PDE6 to outer segments, causing slowly progressing, recessive retinitis pigmentosa. A rare PDE6D null allele in human patients, discovered by Tania Attié-Bitach in France, specifically impeded trafficking of farnesylated phosphatidylinositol 3,4,5-trisphosphate (PIP3) 5-phosphatase (INPP5E) to cilia, causing severe syndromic ciliopathy (Joubert syndrome). Binding of cargo to PDEδ is controlled by Arf-like proteins, ARL2 and ARL3, charged with guanosine-5'-triphosphate (GTP). Arf-like proteins 2 and 3 are unprenylated small GTPases that serve as cargo displacement factors. The lifetime of ARL3(GTP) is controlled by its GTPase-activating protein, retinitis pigmentosa protein 2 (RP2), which accelerates GTPase activity up to 90,000-fold. RP2 null alleles in human patients are associated with severe X-linked retinitis pigmentosa (XLRP). Germline deletion of RP2 in mouse, however, causes only a mild form of XLRP. Absence of RP2 prolongs the activity of ARL3(GTP) that, in turn, impedes PDE6δ-cargo interactions and trafficking of prenylated protein to the outer segments. Hyperactive ARL3(GTP), acting as a hyperactive cargo displacement factor, is predicted to be key in the pathobiology of RP2-XLRP.
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Affiliation(s)
- Wolfgang Baehr
- Department of Ophthalmology, John A. Moran Eye Center, University of Utah Health Science Center, University of Utah, Salt Lake City, Utah, United StatesDepartment of Neurobiology and Anatomy, University of Utah Health Science Center, University of Utah, Salt Lake City, Utah, United StatesDepartment of Biology, University of Utah, Salt Lake City, Utah, United States
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31
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Zhang H, Hanke-Gogokhia C, Jiang L, Li X, Wang P, Gerstner CD, Frederick JM, Yang Z, Baehr W. Mistrafficking of prenylated proteins causes retinitis pigmentosa 2. FASEB J 2014; 29:932-42. [PMID: 25422369 DOI: 10.1096/fj.14-257915] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The retinitis pigmentosa 2 polypeptide (RP2) functions as a GTPase-activating protein (GAP) for ARL3 (Arf-like protein 3), a small GTPase. ARL3 is an effector of phosphodiesterase 6 Δ (PDE6D), a prenyl-binding protein and chaperone of prenylated protein in photoreceptors. Mutations in the human RP2 gene cause X-linked retinitis pigmentosa (XLRP) and cone-rod dystrophy (XL-CORD). To study mechanisms causing XLRP, we generated an RP2 knockout mouse. The Rp2h(-/-) mice exhibited a slowly progressing rod-cone dystrophy simulating the human disease. Rp2h(-/-) scotopic a-wave and photopic b-wave amplitudes declined at 1 mo of age and continued to decline over the next 6 mo. Prenylated PDE6 subunits and G-protein coupled receptor kinase 1 (GRK1) were unable to traffic effectively to the Rp2h(-/-) outer segments. Mechanistically, absence of RP2 GAP activity increases ARL3-GTP levels, forcing PDE6D to assume a predominantly "closed" conformation that impedes binding of lipids. Lack of interaction disrupts trafficking of PDE6 and GRK1 to their destination, the photoreceptor outer segments. We propose that hyperactivity of ARL3-GTP in RP2 knockout mice and human patients with RP2 null alleles leads to XLRP resembling recessive rod-cone dystrophy.
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Affiliation(s)
- Houbin Zhang
- *The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Christin Hanke-Gogokhia
- *The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Li Jiang
- *The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Xiaobo Li
- *The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Pu Wang
- *The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Cecilia D Gerstner
- *The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Jeanne M Frederick
- *The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Zhenglin Yang
- *The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Wolfgang Baehr
- *The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
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Abstract
The ARF-like (ARL) proteins, within the ARF family, are a collection of functionally diverse GTPases that share extensive (>40 %) identity with the ARFs and each other and are assumed to share basic mechanisms of regulation and a very incompletely documented degree of overlapping regulators. At least four ARLs were already present in the last eukaryotic common ancestor, along with one ARF, and these have been expanded to >20 members in mammals. We know little about the majority of these proteins so our review will focus on those about which the most is known, including ARL1, ARL2, ARL3, ARL4s, ARL6, ARL13s, and ARFRP1. From this fragmentary information we extract some generalizations and conclusions regarding the sources and extent of specificity and functions of the ARLs.
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Affiliation(s)
- Alfred Wittinghofer
- Max-Planck-Institute of Molecular Physiology, Dortmund, Nordrhein-Westfalen Germany
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Effect of oxidation of polyunsaturated phospholipids on the binding of proteins in monolayers. Colloids Surf B Biointerfaces 2013; 109:109-14. [DOI: 10.1016/j.colsurfb.2013.03.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/08/2013] [Accepted: 03/12/2013] [Indexed: 11/18/2022]
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Li L, Khan N, Hurd T, Ghosh AK, Cheng C, Molday R, Heckenlively JR, Swaroop A, Khanna H. Ablation of the X-linked retinitis pigmentosa 2 (Rp2) gene in mice results in opsin mislocalization and photoreceptor degeneration. Invest Ophthalmol Vis Sci 2013; 54:4503-11. [PMID: 23745007 DOI: 10.1167/iovs.13-12140] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
PURPOSE Mutations in the RP2 gene are associated with 10% to 15% of X-linked retinitis pigmentosa (XLRP), a debilitating disorder characterized by the degeneration of retinal rod and cone photoreceptors. The molecular mechanism of pathogenesis of photoreceptor degeneration in XLRP-RP2 has not been elucidated, and no treatment is currently available. This study was undertaken to investigate the pathogenesis of RP2-associated retinal degeneration. METHODS We introduced loxP sites that flank exon 2, a mutational hotspot in XLRP-RP2, in the mouse Rp2 gene. We then produced Rp2-null allele using transgenic mice that expressed Cre-recombinase under control of the ubiquitous CAG promoter. Electroretinography (ERG), histology, light microscopy, transmission electron microscopy, and immunofluorescence microscopy were performed to ascertain the effect of ablation of Rp2 on photoreceptor development, function, and protein trafficking. RESULTS Although no gross abnormalities were detected in the Rp2(null) mice, photopic (cone) and scotopic (rod) function as measured by ERG showed a gradual decline starting as early as 1 month of age. We also detected slow progressive degeneration of the photoreceptor membrane discs in the mutant retina. These defects were associated with mislocalization of cone opsins to the nuclear and synaptic layers and reduced rhodopsin content in the outer segment of mutant retina prior to the onset of photoreceptor degeneration. CONCLUSIONS Our studies suggest that RP2 contributes to the maintenance of photoreceptor function and that cone opsin mislocalization represents an early step in XLRP caused by RP2 mutations. The Rp2(null) mice should serve as a useful preclinical model for testing gene- and cell-based therapies.
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Affiliation(s)
- Linjing Li
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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Seixas E, Barros M, Seabra MC, Barral DC. Rab and Arf proteins in genetic diseases. Traffic 2013; 14:871-85. [PMID: 23565987 DOI: 10.1111/tra.12072] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 04/03/2013] [Accepted: 04/08/2013] [Indexed: 01/29/2023]
Abstract
Rab and ADP-ribosylation factor (Arf) family proteins are master regulators of membrane trafficking and are involved in all steps of vesicular transport. These families of small guanine-nucleotide-binding (G) proteins are well suited to regulate membrane trafficking processes since their nucleotide state determines their conformation and the capacity to bind to a multitude of effectors, which mediate their functions. In recent years, several inherited diseases have been associated with mutations in genes encoding proteins belonging to these two families or in proteins that regulate their GTP-binding cycle. The genetic diseases that are caused by defects in Rabs, Arfs or their regulatory proteins are heterogeneous and display diverse symptoms. However, these diseases mainly affect two types of subcellular compartments, namely lysosome-related organelles and cilia. Also, several of these diseases affect the nervous system. Thus, the study of these diseases represents an opportunity to understand their etiology and the molecular mechanisms involved, as well as to develop novel therapeutic strategies.
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Affiliation(s)
- Elsa Seixas
- CEDOC, Faculdade de Ciências Médicas, FCM, Universidade Nova de Lisboa, 1169-056, Lisboa, Portugal
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Raghupathy RK, McCulloch DL, Akhtar S, Al-mubrad TM, Shu X. Zebrafish model for the genetic basis of X-linked retinitis pigmentosa. Zebrafish 2013; 10:62-9. [PMID: 23536988 DOI: 10.1089/zeb.2012.0761] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Retinitis pigmentosa (RP) affects 1/4000 individuals in most populations, and X-linked RP (XLRP) is one of the most severe forms of human retinal degeneration. Mutations in both the retinitis pigmentosa GTPase regulator (RPGR) gene and retinitis pigmentosa 2 (RP2) gene account for almost all cases of XLRP. The functional roles of both RPGR and RP2 in the pathogenesis of XLRP are unclear. Due to the surprisingly high degree of functional conservation between human genes and their zebrafish orthologues, the zebrafish has become an important model for human retinal disorders. In this brief review, we summarize the functional characterization of XLRP-causing genes, RPGR and RP2, in zebrafish, and highlight recent studies that provide insight into the cellular functions of both genes. This will not only shed light on disease mechanisms in XLRP but will also provide a solid platform to test RP-causing mutants before proposing XLRP gene therapy trials.
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Photoreceptor sensory cilia and ciliopathies: focus on CEP290, RPGR and their interacting proteins. Cilia 2012; 1:22. [PMID: 23351659 PMCID: PMC3563624 DOI: 10.1186/2046-2530-1-22] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 09/19/2012] [Indexed: 02/08/2023] Open
Abstract
Ciliopathies encompass a broad array of clinical findings associated with genetic defects in biogenesis and/or function of the primary cilium, a ubiquitous organelle involved in the transduction of diverse biological signals. Degeneration or dysfunction of retinal photoreceptors is frequently observed in diverse ciliopathies. The sensory cilium in a photoreceptor elaborates into unique outer segment discs that provide extensive surface area for maximal photon capture and efficient visual transduction. The daily renewal of approximately 10% of outer segments requires a precise control of ciliary transport. Here, we review the ciliopathies with associated retinal degeneration, describe the distinctive structure of the photoreceptor cilium, and discuss mouse models that allow investigations into molecular mechanisms of cilia biogenesis and defects. We have specifically focused on two ciliary proteins - CEP290 and RPGR - that underlie photoreceptor degeneration and syndromic ciliopathies. Mouse models of CEP290 and RPGR disease, and of their multiple interacting partners, have helped unravel new functional insights into cell type-specific phenotypic defects in distinct ciliary proteins. Elucidation of multifaceted ciliary functions and associated protein complexes will require concerted efforts to assimilate diverse datasets from in vivo and in vitro studies. We therefore discuss a possible framework for investigating genetic networks associated with photoreceptor cilia biogenesis and pathology.
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Schwarz N, Hardcastle AJ, Cheetham ME. Arl3 and RP2 mediated assembly and traffic of membrane associated cilia proteins. Vision Res 2012; 75:2-4. [PMID: 22884633 DOI: 10.1016/j.visres.2012.07.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 07/24/2012] [Accepted: 07/25/2012] [Indexed: 01/17/2023]
Abstract
The traffic of proteins to the outer segment of photoreceptors is a fundamentally important process, which when perturbed results in photoreceptor cell death. Recent reports have revealed a novel pathway for the traffic of lipid-modified proteins involving the small GTPase Arl3 and its effectors PDEδ and Unc119. The retinitis pigmentosa protein RP2 is a GTPase activating protein (GAP) for Arl3 and also appears to regulate the assembly and traffic of membrane associated protein complexes. We recently identified the Gβ subunit of transducin (Gβ1) as a novel RP2 interacting protein. Our data support a role for RP2 in facilitating membrane association and traffic of Gβ1, potentially prior to the formation of the obligate Gβ:Gγ heterodimer. Here, we review the recent evidence that suggests that RP2 co-operates with Arl3 and its effectors in protein complex assembly and membrane specification for lipid-modified proteins. This is exemplified by the co-ordination of cilia associated traffic for heterotrimeric G proteins and we propose a model for the role of Arl3 and RP2 in this process.
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Affiliation(s)
- Nele Schwarz
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
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Schwarz N, Hardcastle AJ, Cheetham ME. The role of the X-linked retinitis pigmentosa protein RP2 in vesicle traffic and cilia function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 723:527-32. [PMID: 22183373 DOI: 10.1007/978-1-4614-0631-0_66] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Nele Schwarz
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
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Schwarz N, Novoselova TV, Wait R, Hardcastle AJ, Cheetham ME. The X-linked retinitis pigmentosa protein RP2 facilitates G protein traffic. Hum Mol Genet 2011; 21:863-73. [PMID: 22072390 DOI: 10.1093/hmg/ddr520] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The X-linked retinitis pigmentosa protein RP2 is a GTPase activating protein (GAP) for the small GTPase Arl3 and both proteins are implicated in the traffic of proteins to the primary cilia. Here, we show that RP2 can facilitate the traffic of the Gβ subunit of transducin (Gβ1). Glutathione S-transferase (GST)-RP2 pulled down Gβ from retinal lysates and the interaction was specific to Gβ1, as Gβ3 or Gβ5L did not bind RP2. RP2 did not appear to interact with the Gβ:Gγ heterodimer, in contrast Gγ1 competed with RP2 for Gβ binding. Overexpression of Gβ1 in SK-N-SH cells led to a cytoplasmic accumulation of Gβ1, while co-expression of RP2 or Gγ1 with Gβ1 restored membrane association of Gβ1. Furthermore, RP2 small interfering RNA in ARPE19 cells resulted in a reduction in Gβ1 membrane association that was rescued by Gγ1 overexpression. The interaction of RP2 with Gβ1 required RP2 N-terminal myristolyation and the co-factor C (TBCC) homology domain. The interaction was also disrupted by the pathogenic mutation R118H, which blocks Arl3 GAP activity. Interestingly, Arl3-Q71L competed with Gβ1 for RP2 binding, suggesting that Arl3-GTP binding by RP2 would release Gβ1. RP2 also stimulated the association of Gβ1 with Rab11 vesicles. Collectively, the data support a role for RP2 in facilitating the membrane association and traffic of Gβ1, potentially prior to the formation of the obligate Gβ:Gγ heterodimer. Combined with other recent evidence, this suggests that RP2 may co-operate with Arl3 and its effectors in the cilia-associated traffic of G proteins.
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Affiliation(s)
- Nele Schwarz
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
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Patil SB, Hurd TW, Ghosh AK, Murga-Zamalloa CA, Khanna H. Functional analysis of retinitis pigmentosa 2 (RP2) protein reveals variable pathogenic potential of disease-associated missense variants. PLoS One 2011; 6:e21379. [PMID: 21738648 PMCID: PMC3124502 DOI: 10.1371/journal.pone.0021379] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 05/26/2011] [Indexed: 11/18/2022] Open
Abstract
Genetic mutations are frequently associated with diverse phenotypic consequences, which limits the interpretation of the consequence of a variation in patients. Mutations in the retinitis pigmentosa 2 (RP2) gene are associated with X-linked RP, which is a phenotypically heterogenic form of retinal degeneration. The purpose of this study was to assess the functional consequence of disease-associated mutations in the RP2 gene using an in vivo assay. Morpholino-mediated depletion of rp2 in zebrafish resulted in perturbations in photoreceptor development and microphthalmia (small eye). Ultrastructural and immunofluorescence analyses revealed defective photoreceptor outer segment development and lack of expression of photoreceptor-specific proteins. The retinopathy phenotype could be rescued by expressing the wild-type human RP2 protein. Notably, the tested RP2 mutants exhibited variable degrees of rescue of rod versus cone photoreceptor development as well as microphthalmia. Our results suggest that RP2 plays a key role in photoreceptor development and maintenance in zebrafish and that the clinical heterogeneity associated with RP2 mutations may, in part, result from its potentially distinct functional relevance in rod versus cone photoreceptors.
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Affiliation(s)
- Suresh B. Patil
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Toby W. Hurd
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Amiya K. Ghosh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Carlos A. Murga-Zamalloa
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Hemant Khanna
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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Williams CL, Li C, Kida K, Inglis PN, Mohan S, Semenec L, Bialas NJ, Stupay RM, Chen N, Blacque OE, Yoder BK, Leroux MR. MKS and NPHP modules cooperate to establish basal body/transition zone membrane associations and ciliary gate function during ciliogenesis. ACTA ACUST UNITED AC 2011; 192:1023-41. [PMID: 21422230 PMCID: PMC3063147 DOI: 10.1083/jcb.201012116] [Citation(s) in RCA: 356] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Eight proteins, defects in which are associated with Meckel-Gruber syndrome and nephronophthisis ciliopathies, work together as two functional modules at the transition zone to establish basal body/transition zone connections with the membrane and barricade entry of non-ciliary components into this organelle. Meckel-Gruber syndrome (MKS), nephronophthisis (NPHP), and related ciliopathies present with overlapping phenotypes and display considerable allelism between at least twelve different genes of largely unexplained function. We demonstrate that the conserved C. elegans B9 domain (MKS-1, MKSR-1, and MKSR-2), MKS-3/TMEM67, MKS-5/RPGRIP1L, MKS-6/CC2D2A, NPHP-1, and NPHP-4 proteins exhibit essential, collective functions at the transition zone (TZ), an underappreciated region at the base of all cilia characterized by Y-shaped assemblages that link axoneme microtubules to surrounding membrane. These TZ proteins functionally interact as members of two distinct modules, which together contribute to an early ciliogenic event. Specifically, MKS/MKSR/NPHP proteins establish basal body/TZ membrane attachments before or coinciding with intraflagellar transport–dependent axoneme extension and subsequently restrict accumulation of nonciliary components within the ciliary compartment. Together, our findings uncover a unified role for eight TZ-localized proteins in basal body anchoring and establishing a ciliary gate during ciliogenesis, and suggest that disrupting ciliary gate function contributes to phenotypic features of the MKS/NPHP disease spectrum.
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Affiliation(s)
- Corey L Williams
- Department of Cell Biology, University of Alabama, Birmingham, AL 35294, USA
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Calvez P, Demers E, Boisselier E, Salesse C. Analysis of the contribution of saturated and polyunsaturated phospholipid monolayers to the binding of proteins. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:1373-9. [PMID: 21210634 DOI: 10.1021/la104097n] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The binding of peripheral proteins to membranes results in different biological effects. The large diversity of membrane lipids is thought to modulate the activity of these proteins. However, information on the selective binding of peripheral proteins to membrane lipids is still largely lacking. Lipid monolayers at the air/water interface are useful model membrane systems for studying the parameters responsible for peripheral protein membrane binding. We have thus measured the maximum insertion pressure (MIP) of two proteins from the photoreceptors, Retinitis pigmentosa 2 (RP2) and recoverin, to estimate their binding to lipid monolayers. Photoreceptor membranes have the unique characteristic that more than 60% of their fatty acids are polyunsaturated, making them the most unsaturated natural membranes known to date. These membranes are also thought to contain significant amounts of saturated phospholipids. MIPs of RP2 and recoverin have thus been measured in the presence of saturated and polyunsaturated phospholipids. MIPs higher than the estimated lateral pressure of biomembranes have been obtained only with a saturated phospholipid for RP2 and with a polyunsaturated phospholipid for recoverin. A new approach was then devised to analyze these data properly. In particular, a parameter called the synergy factor allowed us to highlight the specificity of RP2 for saturated phospholipids and recoverin for polyunsaturated phospholipids as well as to demonstrate clearly the preference of RP2 for saturated phospholipids that are known to be located in microdomains.
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Affiliation(s)
- Philippe Calvez
- LOEX/CUO-Recherche, Centre Hospitalier Affilié Universitaire de Québec, Département d'Ophtalmologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada
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Holopainen JM, Cheng CL, Molday LL, Johal G, Coleman J, Dyka F, Hii T, Ahn J, Molday RS. Interaction and localization of the retinitis pigmentosa protein RP2 and NSF in retinal photoreceptor cells. Biochemistry 2010; 49:7439-47. [PMID: 20669900 DOI: 10.1021/bi1005249] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
RP2 is a ubiquitously expressed protein encoded by a gene associated with X-linked retinitis pigmentosa (XLRP), a retinal degenerative disease that causes severe vision loss. Previous in vitro studies have shown that RP2 binds to ADP ribosylation factor-like 3 (Arl3) and activates its intrinsic GTPase activity, but the function of RP2 in the retina, and in particular photoreceptor cells, remains unclear. To begin to define the role of RP2 in the retina and XLRP, we have conducted biochemical studies to identify proteins in retinal cell extracts that interact with RP2. Here, we show that RP2 interacts with N-ethylmaleimide sensitive factor (NSF) in retinal cells as well as cultured embryonic kidney (HEK293) cells by mass spectrometry-based proteomics and biochemical analysis. This interaction is mediated by the N-terminal domain of NSF. The E138G and DeltaI137 mutations of RP2 known to cause XLRP abolished the interaction of RP2 with the N-terminal domain of NSF. Immunofluorescence labeling studies further showed that RP2 colocalized with NSF in photoreceptors and other cells of the retina. Intense punctate staining of RP2 was observed close to the junction between the inner and outer segments beneath the connecting cilium, as well as within the synaptic region of rod and cone photoreceptors. Our studies indicate that RP2, in addition to serving as a regulator of Arl3, interacts with NSF, and this complex may play an important role in membrane protein trafficking in photoreceptors and other cells of the retina.
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Affiliation(s)
- Juha M Holopainen
- Department of Ophthalmology,University of Helsinki, Helsinki, Finland
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Hurd T, Zhou W, Jenkins P, Liu CJ, Swaroop A, Khanna H, Martens J, Hildebrandt F, Margolis B. The retinitis pigmentosa protein RP2 interacts with polycystin 2 and regulates cilia-mediated vertebrate development. Hum Mol Genet 2010; 19:4330-44. [PMID: 20729296 DOI: 10.1093/hmg/ddq355] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Ciliopathies represent a growing group of human genetic diseases whose etiology lies in defects in ciliogenesis or ciliary function. Given the established entity of renal-retinal ciliopathies, we have been examining the role of cilia-localized proteins mutated in retinitis pigmentosa (RP) in regulating renal ciliogenesis or cilia-dependent signaling cascades. Specifically, this study examines the role of the RP2 gene product with an emphasis on renal and vertebrate development. We demonstrate that in renal epithelia, RP2 localizes to the primary cilium through dual acylation of the amino-terminus. We also show that RP2 forms a calcium-sensitive complex with the autosomal dominant polycystic kidney disease protein polycystin 2. Ablation of RP2 by shRNA promotes swelling of the cilia tip that may be a result of aberrant trafficking of polycystin 2 and other ciliary proteins. Morpholino-mediated repression of RP2 expression in zebrafish results in multiple developmental defects that have been previously associated with ciliary dysfunction, such as hydrocephalus, kidney cysts and situs inversus. Finally, we demonstrate that, in addition to our observed physical interaction between RP2 and polycystin 2, dual morpholino-mediated knockdown of polycystin 2 and RP2 results in enhanced situs inversus, indicating that these two genes also regulate a common developmental process. This work suggests that RP2 may be an important regulator of ciliary function through its association with polycystin 2 and provides evidence of a further link between retinal and renal cilia function.
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Affiliation(s)
- Toby Hurd
- Department of Pediatrics and Communicable Diseases, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, MI 48109, USA.
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Jayasundera T, Branham KEH, Othman M, Rhoades WR, Karoukis AJ, Khanna H, Swaroop A, Heckenlively JR. RP2 phenotype and pathogenetic correlations in X-linked retinitis pigmentosa. ACTA ACUST UNITED AC 2010; 128:915-23. [PMID: 20625056 DOI: 10.1001/archophthalmol.2010.122] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVES To assess the phenotype of patients with X-linked retinitis pigmentosa (XLRP) with RP2 mutations and to correlate the findings with their genotype. METHODS Six hundred eleven patients with RP were screened for RP2 mutations. From this screen, 18 patients with RP2 mutations were evaluated clinically with standardized electroretinography, Goldmann visual fields, and ocular examinations. In addition, 7 well-documented cases from the literature were used to augment genotype-phenotype correlations. RESULTS Of 11 boys younger than 12 years, 10 (91%) had macular involvement and 9 (82%) had best-corrected visual acuity worse than 20/50. Two boys from different families (aged 8 and 12 years) displayed a choroideremia-like fundus, and 9 boys (82%) were myopic (mean error, -7.97 diopters [D]). Of 10 patients with electroretinography data, 9 demonstrated severe rod-cone dysfunction. All 3 female carriers had macular atrophy in 1 or both eyes and were myopic (mean, -6.23 D). All 9 nonsense and frameshift and 5 of 7 missense mutations (71%) resulted in severe clinical presentations. CONCLUSIONS Screening of the RP2 gene should be prioritized in patients younger than 16 years characterized by X-linked inheritance, decreased best-corrected visual acuity (eg, >20/40), high myopia, and early-onset macular atrophy. Patients exhibiting a choroideremia-like fundus without choroideremia gene mutations should also be screened for RP2 mutations. CLINICAL RELEVANCE An identifiable phenotype for RP2-XLRP aids in clinical diagnosis and targeted genetic screening.
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Affiliation(s)
- Thiran Jayasundera
- Department of Ophthalmologyand Visual Sciences, Kellogg Eye Center, University of Michigan, 1000 Wall Street, Ann Arbor, MI 48105, USA
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Murga-Zamalloa CA, Swaroop A, Khanna H. RPGR-containing protein complexes in syndromic and non-syndromic retinal degeneration due to ciliary dysfunction. J Genet 2010; 88:399-407. [PMID: 20090203 DOI: 10.1007/s12041-009-0061-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dysfunction of primary cilia due to mutations in cilia-centrosomal proteins is associated with pleiotropic disorders. The primary (or sensory) cilium of photoreceptors mediates polarized trafficking of proteins for efficient phototransduction. Retinitis pigmentosa GTPase regulator (RPGR) is a cilia-centrosomal protein mutated in >70% of X-linked RP cases and 10%-20% of simplex RP males. Accumulating evidence indicates that RPGR may facilitate the orchestration of multiple ciliary protein complexes. Disruption of these complexes due to mutations in component proteins is an underlying cause of associated photoreceptor degeneration. Here, we highlight the recent developments in understanding the mechanism of cilia-dependent photoreceptor degeneration due to mutations in RPGR and PGR-interacting proteins in severe genetic diseases, including retinitis pigmentosa, Leber congenital amaurosis (LCA), Joubert syndrome, and Senior-Loken syndrome, and explore the physiological relevance of photoreceptor ciliary protein complexes.
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Affiliation(s)
- Carlos A Murga-Zamalloa
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA
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Williams CL, Masyukova SV, Yoder BK. Normal ciliogenesis requires synergy between the cystic kidney disease genes MKS-3 and NPHP-4. J Am Soc Nephrol 2010; 21:782-93. [PMID: 20150540 DOI: 10.1681/asn.2009060597] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Cilia dysfunction contributes to renal cyst formation in multiple human syndromes including nephronophthisis (NPHP), Meckel-Gruber syndrome (MKS), Joubert syndrome (JBTS), and Bardet-Beidl syndrome (BBS). Although genetically heterogeneous, these diseases share several loci that affect cilia and/or basal body proteins, but the functions and interactions of these gene products are incompletely understood. Here, we report that the ciliated sensory neurons (CSNs) of C. elegans express the putative transmembrane protein MKS-3, which localized to the distal end of their dendrites and to the cilium base but not to the cilium itself. Localization of MKS-3 and other known MKS and NPHP proteins partially overlapped. By analyzing mks-3 mutants, we found that ciliogenesis did not require MKS-3; instead, cilia elongated and cilia-mediated chemoreception was abnormal. Genetic analysis indicated that mks-3 functions in a pathway with other mks genes. Furthermore, mks-1 and mks-3 genetically interacted with a separate pathway (involving nphp-1 and nphp-4) to influence proper positioning, orientation, and formation of cilia. Combined disruption of nphp and mks pathways had cell nonautonomous effects on C. elegans sensilla. Taken together, these data demonstrate the importance of mutational load on the presentation and severity of ciliopathies and expand the understanding of the interactions between ciliopathy genes.
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Affiliation(s)
- Corey L Williams
- Department of Cell Biology, University of Alabama at Birmingham Medical Center, Birmingham, Alabama, USA
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49
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Evans RJ, Schwarz N, Nagel-Wolfrum K, Wolfrum U, Hardcastle AJ, Cheetham ME. The retinitis pigmentosa protein RP2 links pericentriolar vesicle transport between the Golgi and the primary cilium. Hum Mol Genet 2010; 19:1358-67. [PMID: 20106869 DOI: 10.1093/hmg/ddq012] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Photoreceptors are complex ciliated sensory neurons. The basal body and periciliary ridge of photoreceptors function in association with the Golgi complex to regulate the export of proteins from the inner segment to the outer segment sensory axoneme. Here, we show that the retinitis pigmentosa protein RP2, which is a GTPase activating protein (GAP) for Arl3, localizes to the ciliary apparatus, namely the basal body and the associated centriole at the base of the photoreceptor cilium. Targeting to the ciliary base was dependent on N-terminal myristoylation. RP2 also localized to the Golgi and periciliary ridge of photoreceptors, which suggested a role for RP2 in regulating vesicle traffic and docking. To explore this hypothesis, we investigated the effect of RP2 depletion and the expression of a constitutively active form of Arl3 (Q71L) on pericentriolar vesicle transport. Kif3a, a component of intraflagellar transport (IFT), is important in cilia maintenance and transport of proteins through the connecting cilium in photoreceptors. Similar to Kif3a and Arl3 depletion, loss of RP2 led to fragmentation of the Golgi network. Depletion of RP2 and dysregulation of Arl3 resulted in dispersal of vesicles cycling cargo from the Golgi complex to the cilium, including the IFT protein IFT20. We propose that RP2 regulation of Arl3 is important for maintaining Golgi cohesion, facilitating the transport and docking of vesicles and thereby carrying proteins to the base of the photoreceptor connecting cilium for transport to the outer segment.
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Murga-Zamalloa C, Swaroop A, Khanna H. Multiprotein complexes of Retinitis Pigmentosa GTPase regulator (RPGR), a ciliary protein mutated in X-linked Retinitis Pigmentosa (XLRP). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 664:105-14. [PMID: 20238008 DOI: 10.1007/978-1-4419-1399-9_13] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mutations in Retinitis Pigmentosa GTPase Regulator (RPGR) are a frequent cause of X-linked Retinitis Pigmentosa (XLRP). The RPGR gene undergoes extensive alternative splicing and encodes for distinct protein isoforms in the retina. Extensive studies using isoform-specific antibodies and mouse mutants have revealed that RPGR predominantly localizes to the transition zone to primary cilia and associates with selected ciliary and microtubule-associated assemblies in photoreceptors. In this chapter, we have summarized recent advances on understanding the role of RPGR in photoreceptor protein trafficking. We also provide new evidence that suggests the existence of discrete RPGR multiprotein complexes in photoreceptors. Piecing together the RPGR-interactome in different subcellular compartments should provide critical insights into the role of alternative RPGR isoforms in associated orphan and syndromic retinal degenerative diseases.
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Affiliation(s)
- Carlos Murga-Zamalloa
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, Ann Arbor, MI 48105, USA
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