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Jiang M, Paniagua AE, Volland S, Wang H, Balaji A, Li DG, Lopes VS, Burgess BL, Williams DS. Microtubule motor transport in the delivery of melanosomes to the actin-rich apical domain of the retinal pigment epithelium. J Cell Sci 2020; 133:jcs242214. [PMID: 32661088 PMCID: PMC7420818 DOI: 10.1242/jcs.242214] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 06/25/2020] [Indexed: 12/20/2022] Open
Abstract
Melanosomes are motile, light-absorbing organelles that are present in pigment cells of the skin and eye. It has been proposed that melanosome localization, in both skin melanocytes and the retinal pigment epithelium (RPE), involves melanosome capture from microtubule motors by an unconventional myosin, which dynamically tethers the melanosomes to actin filaments. Recent studies with melanocytes have questioned this cooperative capture model. Here, we test the model in RPE cells by imaging melanosomes associated with labeled actin filaments and microtubules, and by investigating the roles of different motor proteins. We found that a deficiency in cytoplasmic dynein phenocopies the lack of myosin-7a, in that melanosomes undergo fewer of the slow myosin-7a-dependent movements and are absent from the RPE apical domain. These results indicate that microtubule-based motility is required for the delivery of melanosomes to the actin-rich apical domain and support a capture mechanism that involves both microtubule and actin motors.
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Affiliation(s)
- Mei Jiang
- Departments of Ophthalmology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Antonio E Paniagua
- Departments of Ophthalmology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Stefanie Volland
- Departments of Ophthalmology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Hongxing Wang
- Departments of Ophthalmology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Adarsh Balaji
- Departments of Ophthalmology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - David G Li
- Departments of Ophthalmology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Vanda S Lopes
- Departments of Ophthalmology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Barry L Burgess
- Departments of Ophthalmology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - David S Williams
- Departments of Ophthalmology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Molecular Biology Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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2
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Hazim RA, Karumbayaram S, Jiang M, Dimashkie A, Lopes VS, Li D, Burgess BL, Vijayaraj P, Alva-Ornelas JA, Zack JA, Kohn DB, Gomperts BN, Pyle AD, Lowry WE, Williams DS. Differentiation of RPE cells from integration-free iPS cells and their cell biological characterization. Stem Cell Res Ther 2017; 8:217. [PMID: 28969679 PMCID: PMC5625837 DOI: 10.1186/s13287-017-0652-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 08/16/2017] [Accepted: 08/29/2017] [Indexed: 01/18/2023] Open
Abstract
Background Dysfunction of the retinal pigment epithelium (RPE) is implicated in numerous forms of retinal degeneration. The readily accessible environment of the eye makes it particularly suitable for the transplantation of RPE cells, which can now be derived from autologous induced pluripotent stem cells (iPSCs), to treat retinal degeneration. For RPE transplantation to become feasible in the clinic, patient-specific somatic cells should be reprogrammed to iPSCs without the introduction of reprogramming genes into the genome of the host cell, and then subsequently differentiated into RPE cells that are well characterized for safety and functionality prior to transplantation. Methods We have reprogrammed human dermal fibroblasts to iPSCs using nonintegrating RNA, and differentiated the iPSCs toward an RPE fate (iPSC-RPE), under Good Manufacturing Practice (GMP)-compatible conditions. Results Using highly sensitive assays for cell polarity, structure, organelle trafficking, and function, we found that iPSC-RPE cells in culture exhibited key characteristics of native RPE. Importantly, we demonstrate for the first time with any stem cell-derived RPE cell that live cells are able to support dynamic organelle transport. This highly sensitive test is critical for RPE cells intended for transplantation, since defects in intracellular motility have been shown to promote RPE pathogenesis akin to that found in macular degeneration. To test their capabilities for in-vivo transplantation, we injected the iPSC-RPE cells into the subretinal space of a mouse model of retinal degeneration, and demonstrated that the transplanted cells are capable of rescuing lost RPE function. Conclusions This report documents the successful generation, under GMP-compatible conditions, of human iPSC-RPE cells that possess specific characteristics of healthy RPE. The report adds to a growing literature on the utility of human iPSC-RPE cells for cell culture investigations on pathogenicity and for therapeutic transplantation, by corroborating findings of others, and providing important new information on essential RPE cell biological properties. Electronic supplementary material The online version of this article (doi:10.1186/s13287-017-0652-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Roni A Hazim
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA
| | - Saravanan Karumbayaram
- Department of Microbiology Immunology and Molecular Genetics, Los Angeles, CA, USA. .,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA. .,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA.
| | - Mei Jiang
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA
| | - Anupama Dimashkie
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA
| | - Vanda S Lopes
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA
| | - Douran Li
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA.,Department of Molecular Cell and Developmental Biology, Los Angeles, CA, USA
| | - Barry L Burgess
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA
| | - Preethi Vijayaraj
- Department of Pediatrics, David Geffen School of Medicine, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | | | - Jerome A Zack
- Department of Microbiology Immunology and Molecular Genetics, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA.,Department of Medicine, David Geffen School of Medicine, Los Angeles, CA, USA
| | - Donald B Kohn
- Department of Microbiology Immunology and Molecular Genetics, Los Angeles, CA, USA.,Department of Pediatrics, David Geffen School of Medicine, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - Brigitte N Gomperts
- Department of Pediatrics, David Geffen School of Medicine, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - April D Pyle
- Department of Microbiology Immunology and Molecular Genetics, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - William E Lowry
- Department of Molecular Cell and Developmental Biology, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - David S Williams
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA. .,Department of Neurobiology, David Geffen School of Medicine, Los Angeles, CA, USA. .,Molecular Biology Institute, Los Angeles, CA, USA. .,Brain Research Institute, University of California, Los Angeles, CA, USA.
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3
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Abstract
Fast protein liquid chromatography (FPLC) is a form of high-performance chromatography that takes advantage of the high resolution made possible by small-diameter stationary phases. It was originally developed for proteins and features high loading capacity, biocompatible aqueous buffer systems, fast flow rates, and availability of stationary phases in most common chromatography modes (e.g., ion exchange, gel filtration, reversed phase, and affinity). The system makes reproducible separation possible by incorporating a high level of automation including autosamplers, gradient program control, and peak collection. In addition to proteins, the method is applicable to other kinds of biological samples including oligonucleotides and plasmids. The most common type of FPLC experiment is anion exchange of proteins. This chapter describes such an experiment carried out using an ÄKTA FPLC explorer system (Amersham Pharmacia Biotech, Sweden).
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Affiliation(s)
- Ashkan Madadlou
- Tehran University, Food Science and Engineering, Karadj, Iran
| | - Siobhan O'Sullivan
- Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland
- Department of Biochemistry, University College Cork, Lee Maltings, Prospect Row, Mardyke, Cork, Ireland
| | - David Sheehan
- Department of Biochemistry, University College Cork, Lee Maltings, Prospect Row, Mardyke, Cork, Ireland.
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4
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Wensel TG, Zhang Z, Anastassov IA, Gilliam JC, He F, Schmid MF, Robichaux MA. Structural and molecular bases of rod photoreceptor morphogenesis and disease. Prog Retin Eye Res 2016; 55:32-51. [PMID: 27352937 PMCID: PMC5112133 DOI: 10.1016/j.preteyeres.2016.06.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 06/14/2016] [Accepted: 06/20/2016] [Indexed: 12/15/2022]
Abstract
The rod cell has an extraordinarily specialized structure that allows it to carry out its unique function of detecting individual photons of light. Both the structural features of the rod and the metabolic processes required for highly amplified light detection seem to have rendered the rod especially sensitive to structural and metabolic defects, so that a large number of gene defects are primarily associated with rod cell death and give rise to blinding retinal dystrophies. The structures of the rod, especially those of the sensory cilium known as the outer segment, have been the subject of structural, biochemical, and genetic analysis for many years, but the molecular bases for rod morphogenesis and for cell death in rod dystrophies are still poorly understood. Recent developments in imaging technology, such as cryo-electron tomography and super-resolution fluorescence microscopy, in gene sequencing technology, and in gene editing technology are rapidly leading to new breakthroughs in our understanding of these questions. A summary is presented of our current understanding of selected aspects of these questions, highlighting areas of uncertainty and contention as well as recent discoveries that provide new insights. Examples of structural data from emerging imaging technologies are presented.
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Affiliation(s)
- Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Zhixian Zhang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ivan A Anastassov
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jared C Gilliam
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Feng He
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael F Schmid
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael A Robichaux
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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5
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Stuck MW, Conley SM, Naash MI. PRPH2/RDS and ROM-1: Historical context, current views and future considerations. Prog Retin Eye Res 2016; 52:47-63. [PMID: 26773759 DOI: 10.1016/j.preteyeres.2015.12.002] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 12/23/2015] [Accepted: 12/30/2015] [Indexed: 11/29/2022]
Abstract
Peripherin 2 (PRPH2), also known as RDS (retinal degeneration slow) is a photoreceptor specific glycoprotein which is essential for normal photoreceptor health and vision. PRPH2/RDS is necessary for the proper formation of both rod and cone photoreceptor outer segments, the organelle specialized for visual transduction. When PRPH2/RDS is defective or absent, outer segments become disorganized or fail to form entirely and the photoreceptors subsequently degenerate. Multiple PRPH2/RDS disease-causing mutations have been found in humans, and they are associated with various blinding diseases of the retina such as macular degeneration and retinitis pigmentosa, the vast majority of which are inherited dominantly, though recessive LCA and digenic RP have also been associated with RDS mutations. Since its initial discovery, the scientific community has dedicated a considerable amount of effort to understanding the molecular function and disease mechanisms of PRPH2/RDS. This work has led to an understanding of how the PRPH2/RDS molecule assembles into complexes and functions as a necessary part of the machinery that forms new outer segment discs, as well as leading to fundamental discoveries about the mechanisms that underlie OS biogenesis. Here we discuss PRPH2/RDS-associated research and how experimental results have driven the understanding of the PRPH2/RDS protein and its role in human disease.
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Affiliation(s)
- Michael W Stuck
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Shannon M Conley
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204-5060, USA.
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6
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Kevany BM, Tsybovsky Y, Campuzano IDG, Schnier PD, Engel A, Palczewski K. Structural and functional analysis of the native peripherin-ROM1 complex isolated from photoreceptor cells. J Biol Chem 2013; 288:36272-84. [PMID: 24196967 DOI: 10.1074/jbc.m113.520700] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Peripherin and its homologue ROM1 are retina-specific members of the tetraspanin family of integral membrane proteins required for morphogenesis and maintenance of photoreceptor outer segments, regions that collect light stimuli. Over 100 pathogenic mutations in peripherin cause inherited rod- and cone-related dystrophies in humans. Peripherin and ROM1 interact in vivo and are predicted to form a core heterotetrameric complex capable of creating higher order oligomers. However, structural analysis of tetraspanin proteins has been hampered by their resistance to crystallization. Here we present a simplified methodology for high yield purification of peripherin-ROM1 from bovine retinas that permitted its biochemical and biophysical characterization. Using size exclusion chromatography and blue native gel electrophoresis, we confirmed that the core native peripherin-ROM1 complex exists as a tetramer. Peripherin, but not ROM1, is glycosylated and we examined the glycosylation site and glycan composition of ROM1 by liquid chromatographic tandem mass spectrometry. Mass spectrometry was used to analyze the native complex in detergent micelles, demonstrating its tetrameric state. Our electron microscopy-generated structure solved to 18 Å displayed the tetramer as an elongated structure with an apparent 2-fold symmetry. Finally, we demonstrated that peripherin-ROM1 tetramers induce membrane curvature when reconstituted in lipid vesicles. These results provide critical insights into this key retinal component with a poorly defined function.
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Affiliation(s)
- Brian M Kevany
- From the Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965 and
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7
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Haeseleer F, Sokal I, Gregory FD, Lee A. Protein phosphatase 2A dephosphorylates CaBP4 and regulates CaBP4 function. Invest Ophthalmol Vis Sci 2013; 54:1214-26. [PMID: 23341017 DOI: 10.1167/iovs.12-11319] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE CaBP4 is a neuronal Ca(2+)-binding protein that is expressed in the retina and in the cochlea, and is essential for normal photoreceptor synaptic function. CaBP4 is phosphorylated by protein kinase C zeta (PKCζ) in the retina at serine 37, which affects its interaction with and modulation of voltage-gated Ca(v)1 Ca(2+) channels. In this study, we investigated the potential role and functional significance of protein phosphatase 2A (PP2A) in CaBP4 dephosphorylation. METHODS The effect of protein phosphatase inhibitors, light, and overexpression of PP2A subunits on CaBP4 dephosphorylation was measured in in vitro assays. Pull-down experiments using retinal or transfected HEK293 cell lysates were used to investigate the association between CaBP4 and PP2A subunits. Electrophysiologic recordings of cotransfected HEK293 cells were performed to analyze the effect of CaBP4 dephosphorylation in modulating Ca(v)1.3 currents. RESULTS PP2A inhibitors, okadaic acid (OA), and fostriecin, but not PP1 selective inhibitors, NIPP-1, and inhibitor 2, block CaBP4 dephosphorylation in retinal lysates. Increased phosphatase activity in light-dependent conditions reverses phosphorylation of CaBP4 by PKCζ. In HEK293 cells, overexpression of PP2A enhances the rate of dephosphorylation of CaBP4. In addition, inhibition of protein phosphatase activity by OA increases CaBP4 phosphorylation and potentiates the modulatory effect of CaBP4 on Ca(v)1.3 Ca(2+) channels in HEK293T cells. CONCLUSIONS This study provides evidence that CaBP4 is dephosphorylated by PP2A in the retina. Our findings reveal a novel role for protein phosphatases in regulating CaBP4 function in the retina, which may fine tune presynaptic Ca(2+) signals at the photoreceptor synapse.
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Affiliation(s)
- Françoise Haeseleer
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA.
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8
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Conley SM, Stuck MW, Naash MI. Structural and functional relationships between photoreceptor tetraspanins and other superfamily members. Cell Mol Life Sci 2011; 69:1035-47. [PMID: 21655915 DOI: 10.1007/s00018-011-0736-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 05/12/2011] [Accepted: 05/16/2011] [Indexed: 12/14/2022]
Abstract
The two primary photoreceptor-specific tetraspanins are retinal degeneration slow (RDS) and rod outer segment membrane protein-1 (ROM-1). These proteins associate together to form different complexes necessary for the proper structure of the photoreceptor outer segment rim region. Mutations in RDS cause blinding retinal degenerative disease in both rods and cones by mechanisms that remain unknown. Tetraspanins are implicated in a variety of cellular processes and exert their function via the formation of tetraspanin-enriched microdomains. This review focuses on correlations between RDS and other members of the tetraspanin superfamily, particularly emphasizing protein structure, complex assembly, and post-translational modifications, with the goal of furthering our understanding of the structural and functional role of RDS and ROM-1 in outer segment morphogenesis and maintenance, and our understanding of the pathogenesis associated with RDS and ROM-1 mutations.
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Affiliation(s)
- Shannon M Conley
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, 73104, USA
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9
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Edrington TC, Sokolov M, Boesze-Battaglia K. Peripherin/rds co-distributes with putative binding partners in basal rod outer segment disks. Exp Eye Res 2011; 92:439-42. [PMID: 21440543 PMCID: PMC3871196 DOI: 10.1016/j.exer.2011.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 03/16/2011] [Accepted: 03/17/2011] [Indexed: 11/19/2022]
Affiliation(s)
- Thomas C. Edrington
- Center for Membrane Biology Department of Molecular Physiology and Biological Physics University of Virginia School of Medicine Charlottesville, VA 22908-0886
| | - Maxim Sokolov
- Departments of Ophthalmology and Biochemistry West Virginia University School of Medicine, Morgantown, West Virginia , 26506,USA.
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10
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Abstract
Fast protein liquid chromatography (FPLC) is a form of high-performance chromatography that takes advantage of high resolution made possible by small-diameter stationary phases. It was originally developed for proteins and features high loading capacity, biocompatible aqueous buffer systems, fast flow rates, and availability of stationary phases in most common chromatography modes (e.g., ion exchange, gel filtration, reversed phase, and affinity). The system makes reproducible separation possible by incorporating a high level of automation including autosamplers, gradient program control, and peak collection. In addition to proteins, the method is applicable to other kinds of biological samples including oligonucleotides and plasmids. The most common type of FPLC experiment is anion exchange of proteins. This chapter describes such an experiment carried out using an ÄKTA FPLC explorer system (Amersham Pharmacia Biotech, Sweden).
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Affiliation(s)
- Ashkan Madadlou
- Food Science and Engineering, Tehran University, Karadj, Iran
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11
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FARJO RAFAL, FLIESLER STEVENJ, NAASH MUNAI. Effect of Rds abundance on cone outer segment morphogenesis, photoreceptor gene expression, and outer limiting membrane integrity. J Comp Neurol 2008; 504:619-30. [PMID: 17722028 PMCID: PMC2072815 DOI: 10.1002/cne.21476] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We examined the molecular, structural, and functional consequences on cone photoreceptors of the neural retinal leucine zipper knockout (Nrl(-/-)) mice when only one allele of retinal degeneration slow (Rds) is present (Rds(+/-)/Nrl(-/-)). Quantitative RT-PCR and immunoblot analysis were used to assess the expression levels of several phototransduction genes; electroretinography was used to assess quantitatively the retinal responsiveness to light; and immunohistochemistry and ultrastructural analysis were used to examine retinal protein distribution and morphology, respectively. In Rds/Nrl double-null mice, S-cones form dysmorphic outer segments that lack lamellae and fail to associate properly with the cone matrix sheath and the outer limiting membrane. In Rds(+/-)/Nrl(-/-) mice, cones form oversized and disorganized outer segment lamellae; although outer limiting membrane associations are maintained, normal interactions with cone matrix sheaths are not, and photoreceptor rosette formation is observed. These retinas produce significantly higher photopic a-wave and b-wave amplitudes than do those of Rds(-/-)/Nrl(-/-) mice, and the levels of several cone phototransduction genes are significantly increased coincidently with the presence of Rds and partial lamellae formation. Thus, as in rod photoreceptors, expression of only one Rds allele is unable to support normal outer segment morphogenesis in cones. However, cone lamellae assembly, albeit disorganized, concomitantly permits outer limiting membrane association, and this appears to be linked to photoreceptor rosette formation in the rodless (cone-only) Nrl(-/-) retina. In addition, photoreceptor gene expression alterations occur in parallel with changes in Rds levels.
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Affiliation(s)
- RAFAL FARJO
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - STEVEN J. FLIESLER
- Departments of Ophthalmology and Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - MUNA I. NAASH
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
- *Correspondence to: Muna I. Naash, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 781, Oklahoma City, OK 73104. E-mail:
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12
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Lee A, Jimenez A, Cui G, Haeseleer F. Phosphorylation of the Ca2+-binding protein CaBP4 by protein kinase C zeta in photoreceptors. J Neurosci 2007; 27:12743-54. [PMID: 18003854 PMCID: PMC2703458 DOI: 10.1523/jneurosci.4264-07.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Accepted: 10/09/2007] [Indexed: 11/21/2022] Open
Abstract
CaBP4 is a calmodulin-like neuronal calcium-binding protein that is crucial for the development and/or maintenance of the cone and rod photoreceptor synapse. Previously, we showed that CaBP4 directly regulates Ca(v)1 L-type Ca2+ channels, which are essential for normal photoreceptor synaptic transmission. Here, we show that the function of CaBP4 is regulated by phosphorylation. CaBP4 is phosphorylated by protein kinase C zeta (PKCzeta) at serine 37 both in vitro and in the retina and colocalizes with PKCzeta in photoreceptors. CaBP4 phosphorylation is greater in light-adapted than dark-adapted mouse retinas. In electrophysiological recordings of cells transfected with Ca(v)1.3 and CaBP4, mutation of the serine 37 to alanine abolished the effect of CaBP4 in prolonging the Ca2+ current through Ca(v)1.3 channel, whereas inactivating mutations in the CaBP4 Ca2+-binding sites strengthened Ca(v)1.3 modulation. These findings demonstrate how light-stimulated changes in CaBP4 phosphorylation and Ca2+ binding may regulate presynaptic Ca2+ signals in photoreceptors.
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Affiliation(s)
- Amy Lee
- Department of Pharmacology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322, and
| | - Amber Jimenez
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195
| | - Guiying Cui
- Department of Pharmacology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322, and
| | - Françoise Haeseleer
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195
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13
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Boesze-Battaglia K, Song H, Sokolov M, Lillo C, Pankoski-Walker L, Gretzula C, Gallagher B, Rachel RA, Jenkins NA, Copeland NG, Morris F, Jacob J, Yeagle P, Williams DS, Damek-Poprawa M. The tetraspanin protein peripherin-2 forms a complex with melanoregulin, a putative membrane fusion regulator. Biochemistry 2007; 46:1256-72. [PMID: 17260955 PMCID: PMC4472003 DOI: 10.1021/bi061466i] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peripherin-2, the product of the rds gene, is a tetraspanin protein. In this study, we show that peripherin-2 forms a complex with melanoregulin (MREG), the product of the Mreg locus. Genetic studies suggest that MREG is involved in organelle biogenesis. In this study, we explore the role of this protein in processes associated with the formation of disk membranes, specialized organelles of photoreceptor rod cells. MREG antibodies were generated and found to be immunoreactive with a 28 kDa protein in retinal extracts, bovine OS, ARPE-19 cells, and rat RPE. MREG colocalized with peripherin-2 in WT (CB6F1/J) and in rds+/- retinas. Western blots of serial tangential sections confirmed the close association of these two proteins within the IS and basal outer segment of rods. Immunoprecipitation (IP) of OS extracts showed formation of a complex between MREG and peripherin-2-ROM-1 hetero-oligomers. This interaction was confirmed with pulldown analyses in which the GST-PerCter protein selectively pulled down His-MREG and His-MREG selectively pulled down PerCter. Biacore analysis using peptide inhibitors and per-2 truncation mutant studies allowed us to map the MREG binding site on per-2 to the last five residues of the C-terminus (Gln341-Gly346), and kinetic data predicted a KD of 80 nM for PerCter-MREG binding. Finally, the effect of MREG on photoreceptor specific membrane fusion was assayed using a disk-plasma membrane cell free assay. Preincubation of target membranes with MREG resulted in a dose-dependent inhibition of fusion with an IC50 in the submicromolar range. Collectively, these results suggest that this newly identified protein regulates peripherin-2 function.
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Affiliation(s)
- Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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14
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Edrington TC, Yeagle PL, Gretzula CL, Boesze-Battaglia K. Calcium-dependent association of calmodulin with the C-terminal domain of the tetraspanin protein peripherin/rds. Biochemistry 2007; 46:3862-71. [PMID: 17323925 PMCID: PMC4721525 DOI: 10.1021/bi061999r] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Peripherin/rds (p/rds), an integral membrane protein from the transmembrane 4 (TMF4) superfamily, possesses a multi-functional C-terminal domain that plays crucial roles in rod outer segment (ROS) disk renewal and structure. Here, we report that the calcium binding protein calmodulin (CaM) binds to the C-terminal domain of p/rds. Fluorescence spectroscopy reveals Ca2+-dependent association of CaM with a polypeptide corresponding to the C-terminal domain of p/rds. The fluorescence anisotropy of the polypeptide upon CaM titration yields a dissociation constant (KD) of 320 +/- 150 nM. The results of the fluorescence experiments were confirmed by GST-pull down analyses in which a GST-p/rds C-terminal domain fusion protein was shown to pull down CaM in a calcium-dependent manner. Moreover, molecular modeling and sequence predictions suggest that the CaM binding domain resides in a p/rds functional hot spot, between residues E314 and G329. Predictions were confirmed by peptide competition studies and a GST-p/rds C-terminal domain construct in which the putative Ca2+/CaM binding site was scrambled. This GST-polypeptide did not associate with Ca2+/CaM. This putative calmodulin domain is highly conserved between human, mouse, rat, and bovine p/rds. Finally, the binding of Ca2+/CaM inhibited fusion between ROS disk and ROS plasma membranes as well as p/rds C-terminal-domain-induced fusion in model membrane studies. These results offer a new mechanism for the modulation of p/rds function.
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Affiliation(s)
| | - P. L. Yeagle
- To whom correspondence should be addressed. Phone: 860-486-5154. Fax: 860-486-4331.
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15
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Boesze-Battaglia K, Stefano FP, Fitzgerald C, Muller-Weeks S. ROM-1 potentiates photoreceptor specific membrane fusion processes. Exp Eye Res 2006; 84:22-31. [PMID: 17055485 PMCID: PMC1829207 DOI: 10.1016/j.exer.2006.08.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 08/20/2006] [Accepted: 08/23/2006] [Indexed: 11/23/2022]
Abstract
Photoreceptor outer segment (OS) renewal requires a series of tightly regulated membrane fusion events which are mediated by a fusion complex containing protein and lipid components. The best characterized of these components, is a unique photoreceptor specific tetraspanin, peripherin/rds (P/rds, a.k.a., peripherin-2, Rds and Prph). In these studies we investigated the role of peripherin's non-glycosylated homolog, ROM-1, in OS fusion using a COS cell heterologous expression system and a well characterized cell free fusion assay system. Membranes isolated from COS-7 cells transfected with either FLAG-tagged P/rds or HA-tagged ROM-1 or both proteins were assayed for their ability to merge with fluorescently labeled OS plasma membrane (PM). Such membrane merger is one measure of membrane fusogenicity. The highest percent fusion was observed when the proteins were co-expressed. Furthermore detailed analysis of the fusion kinetics between fluorescently labeled PM and proteo-liposomes containing either, pure P/rds, pure ROM-1 or the ROM-1-P/rds complex clearly demonstrated that optimal fusion requires an ROM-1/P/rds complex. Proteo-liposomes composed of ROM-1 alone were not fusogenic. Peptide competition studies suggest that optimization of fusion may be due to the formation of a fusion competent peripherin/rds C-terminus in the presence of ROM-1. These studies provide further support for the hypothesis that a P/rds dependent membrane fusion complex is involved in photoreceptor renewal processes.
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Affiliation(s)
- Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Philadelphia, PA 19104, USA.
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16
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Goldberg AFX. Role of Peripherin/rds in Vertebrate Photoreceptor Architecture and Inherited Retinal Degenerations. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 253:131-75. [PMID: 17098056 DOI: 10.1016/s0074-7696(06)53004-9] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The vertebrate photoreceptor outer segment (OS) is a highly structured and dynamic organelle specialized to transduce light signals. The elaborate membranous architecture of the OS requires peripherin/rds (P/rds), an integral membrane protein and tetraspanin protein family member. Gene-level defects in P/rds cause a broad variety of late-onset progressive retinal degenerations in humans and dysmorphic photoreceptors in murine and Xenopus models. Although proposed to fulfill numerous roles related to OS structural stability and renewal, P/rds molecular function remains uncertain. An increasingly resolved model of this protein's oligomeric structure can account for disease inheritance patterns and severity in some instances. Nonetheless, the pathogenic mechanisms underlying the uniquely broad spectrum of retinal diseases associated with P/rds defects are not currently well understood. Recent findings point to the possibility that P/rds acts as a multifunctional scaffolding protein for OS architecture and that partial-loss-of-function mutations contribute to the hallmark phenotypic heterogeneity associated with inherited defects in RDS.
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17
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Abstract
The photoreceptor rod outer segment (ROS) provides a unique system in which to investigate the role of cholesterol, an essential membrane constituent of most animal cells. The ROS is responsible for the initial events of vision at low light levels. It consists of a stack of disk membranes surrounded by the plasma membrane. Light capture occurs in the outer segment disk membranes that contain the photopigment, rhodopsin. These membranes originate from evaginations of the plasma membrane at the base of the outer segment. The new disks separate from the plasma membrane and progressively move up the length of the ROS over the course of several days. Thus the role of cholesterol can be evaluated in two distinct membranes. Furthermore, because the disk membranes vary in age it can also be investigated in a membrane as a function of the membrane age. The plasma membrane is enriched in cholesterol and in saturated fatty acids species relative to the disk membrane. The newly formed disk membranes have 6-fold more cholesterol than disks at the apical tip of the ROS. The partitioning of cholesterol out of disk membranes as they age and are apically displaced is consistent with the high PE content of disk membranes relative to the plasma membrane. The cholesterol composition of membranes has profound consequences on the major protein, rhodopsin. Biophysical studies in both model membranes and in native membranes have demonstrated that cholesterol can modulate the activity of rhodopsin by altering the membrane hydrocarbon environment. These studies suggest that mature disk membranes initiate the visual signal cascade more effectively than the newly synthesized, high cholesterol basal disks. Although rhodopsin is also the major protein of the plasma membrane, the high membrane cholesterol content inhibits rhodopsin participation in the visual transduction cascade. In addition to its effect on the hydrocarbon region, cholesterol may interact directly with rhodopsin. While high cholesterol inhibits rhodopsin activation, it also stabilizes the protein to denaturation. Therefore the disk membrane must perform a balancing act providing sufficient cholesterol to confer stability but without making the membrane too restrictive to receptor activation. Within a given disk membrane, it is likely that cholesterol exhibits an asymmetric distribution between the inner and outer bilayer leaflets. Furthermore, there is some evidence of cholesterol microdomains in the disk membranes. The availability of the disk protein, rom-1 may be sensitive to membrane cholesterol. The effects exerted by cholesterol on rhodopsin function have far-reaching implications for the study of G-protein coupled receptors as a whole. These studies show that the function of a membrane receptor can be modulated by modification of the lipid bilayer, particularly cholesterol. This provides a powerful means of fine-tuning the activity of a membrane protein without resorting to turnover of the protein or protein modification.
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Affiliation(s)
- Arlene D Albert
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA.
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18
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Damek-Poprawa M, Krouse J, Gretzula C, Boesze-Battaglia K. A novel tetraspanin fusion protein, peripherin-2, requires a region upstream of the fusion domain for activity. J Biol Chem 2004; 280:9217-24. [PMID: 15591062 DOI: 10.1074/jbc.m407166200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Peripherin-2 (also known as peripherin/rds), a photoreceptor specific tetraspanin protein, is required to maintain normal cell structure through its role in renewal processes requiring membrane fusion. It is the first tetraspanin fusogen and has been shown to directly mediate fusion between disk membranes and opposing membranes to maintain the highly ordered structure of rod outer segments. Localized to the C terminus of human, bovine, and murine peripherin-2 is an amphiphilic fusion peptide domain (residues 312-326) and a highly conserved region upstream of this domain that we hypothesize is essential for fusogenic function. Our previous studies indicated that substitution of a threonine for a proline at position 296 within this highly conserved region enhanced fusion activity. In this study we wanted to determine whether this proline is essential with the introduction of three additional substitutions of proline with alanine, leucine, and glutamic acid. Wild type, P296T, P296A, P296L, and P296E mutants of peripherin-2 were expressed as His6-tagged full-length proteins in Madin-Darby canine kidney (MDCK) cells. All of the proteins were localized to intracellular membranes and detected as 42-kDa monomers by Western blot analysis. The wild type, P296A, and P296L assembled into core tetramers; in contrast the P296T and P296E formed higher order oligomers. Fusogenic activity of full-length protein expressed in MDCK membranes and purified protein reconstituted in model membrane liposomes was determined using fluorescence quenching techniques. Fusion activity was decreased in the P296L, P296A, and P296E mutants both in endogenous MDCK membranes and in model liposomes. Collectively, these results suggest that the proline at position 296 is necessary for optimal function.
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Affiliation(s)
- Monika Damek-Poprawa
- Department of Biochemistry, University of Pennsylvania, School of Dental Medicine, Philadelphia, Pennsylvania 19104, USA
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Ritter LM, Boesze-Battaglia K, Tam BM, Moritz OL, Khattree N, Chen SC, Goldberg AFX. Uncoupling of photoreceptor peripherin/rds fusogenic activity from biosynthesis, subunit assembly, and targeting: a potential mechanism for pathogenic effects. J Biol Chem 2004; 279:39958-67. [PMID: 15252042 PMCID: PMC1360210 DOI: 10.1074/jbc.m403943200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inherited defects in the RDS gene cause a multiplicity of progressive retinal diseases in humans. The gene product, peripherin/rds (P/rds), is a member of the tetraspanin protein family required for normal vertebrate photoreceptor outer segment (OS) architecture. Although its molecular function remains uncertain, P/rds has been suggested to catalyze membrane fusion events required for the OS renewal process. This study investigates the importance of two charged residues within a predicted C-terminal helical region for protein biosynthesis, localization, and interaction with model membranes. Targeted mutagenesis was utilized to neutralize charges at Glu(321) and Lys(324) individually and in combination to generate three mutant variants. Studies were conducted on variants expressed as 1) full-length P/rds in COS-1 cells, 2) glutathione S-transferase fusion proteins in Escherichia coli, and 3) membrane-associated green fluorescent protein fusion proteins in transgenic Xenopus laevis. None of the mutations affected biosynthesis of full-length P/rds in COS-1 cells as assessed by Western blotting, sedimentation velocity, and immunofluorescence microscopy. Although all mutations reside within a recently identified localization signal, none altered the ability of this region to direct OS targeting in transgenic X. laevis retinas. In contrast, individual or simultaneous neutralization of the charged amino acids Glu(321) and Lys(324) abolished the ability of the C-terminal domain to promote model membrane fusion as assayed by lipid mixing. These results demonstrate that, although overlapping, C-terminal determinants responsible for OS targeting and fusogenicity are separable and that fusogenic activity has been uncoupled from other protein properties. The observation that subunit assembly and OS targeting can both proceed normally in the absence of fusogenic activity suggests that properly assembled and targeted yet functionally altered proteins could potentially generate pathogenic effects within the vertebrate photoreceptor.
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Affiliation(s)
- Linda M Ritter
- Eye Research Institute, Oakland University, Rochester, Michigan 48309, USA
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Boesze-Battaglia K, Goldberg AFX, Dispoto J, Katragadda M, Cesarone G, Albert AD. A soluble peripherin/Rds C-terminal polypeptide promotes membrane fusion and changes conformation upon membrane association. Exp Eye Res 2003; 77:505-14. [PMID: 12957149 PMCID: PMC4732724 DOI: 10.1016/s0014-4835(03)00151-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photoreceptor rod cells contain a unique tetraspanin fusion protein known as peripherin/rds. This protein is important in membrane fusion events hypothesized to be essential to disk membrane morphogenesis and disk shedding. In vivo and in vitro fusogenic activity has been mapped to the C-terminal domain of peripherin/rds. Moreover, a fusion peptide domain localized to a 15 amino acid long region (residues 311-325) is essential for mediating lipid bilayer fusion of model membranes. To address the functional and structural properties required for peripherin/rds dependent membrane fusion, constructs of the entire C-terminal domain (residues 284-346) were generated and polypeptides expressed. A wild type-peripherin/rds C-terminal GST fusion construct that included the entire C-terminus (PERCTER) or a C-terminal truncation mutant (PERCTN) were engineered with a thrombin cleavage site. Protein expression was induced in E. coli with IPTG, expressed proteins cleaved from the GST with thrombin and purified to homogeneity on a Superdex 75 column. Purity was confirmed by SDS-PAGE and Western blot analysis. The purified wt C-terminal protein resolved as a monomer under reducing conditions on SDS-PAGE (15%) and was immunoreactive with anti peripherin/rds antibody 2B6 (gift from Dr R. Molday). The purified polypeptide promoted the requisite steps of fusion, membrane destabilization, lipid mixing and aqueous contents mixing. Conversely, the truncation mutant lacking a portion of the fusion domain was unable to promote these steps. A common feature of most membrane fusion proteins is a change in conformation upon membrane association. Structural changes in the C-terminal polypeptide were investigated using far UV CD. The far UV CD spectra of the purified C-terminal polypeptide indicated substantial alpha-helical content in the wt peptide in isotonic aqueous buffer. An increase in intensity of 208 and 222 nm CD bands upon addition of DPC vesicles indicated an increase in alpha-helical content of the polypeptide. These results demonstrate that a purified soluble form of the C-terminus of peripherin/rds can interact with biological phospholipids; moreover, this interaction promotes a conformational change that is most consistent with an increase in alpha-helical content.
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Affiliation(s)
- Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, 4001 Spruce Street, University of Pennsylvania, Philadelphia 19104, USA.
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Schatz P, Abrahamson M, Eksandh L, Ponjavic V, Andréasson S. Macular appearance by means of OCT and electrophysiology in members of two families with different mutations inRDS(the peripherin/RDS gene). ACTA ACUST UNITED AC 2003; 81:500-7. [PMID: 14510799 DOI: 10.1034/j.1600-0420.2003.00134.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
PURPOSE To describe the phenotype using electroretinography and optical coherence tomography (OCT) in members of two families with different mutations in RDS. METHODS DNA was extracted from blood samples and used for mutation screening by denaturing gradient gel electrophoresis (DGGE) and nucleotide sequencing of RDS exons. Patients were examined with clinical evaluation, full-field electroretinography (ERG), multifocal electroretinography (mfERG) and OCT. RESULTS An Arg-46 --> stop codon conversion and a Ser-125 --> Leu substitution were found, respectively, in affected members of the two families. Phenotypes included retinitis pigmentosa, central areolar choroidal dystrophy, macular dystrophy and adult vitelliform maculopathy. The vitelliform lesion was clearly delineated on OCT, but mfERG showed preserved function. Optical coherence tomography showed attenuation of retinal reflectivity in two cases. CONCLUSION By combining traditional investigations with mfERG and OCT, we were able to obtain a more refined evaluation of contributing macular and generalized retinal dysfunction, respectively, in patients with hereditary retinal disease.
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Affiliation(s)
- Patrik Schatz
- Department of Ophthalmology, Lund University Hospital, 221 85 Lund, Sweden.
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Boesze-Battaglia K, Dispoto J, Kahoe MA. Association of a photoreceptor-specific tetraspanin protein, ROM-1, with triton X-100-resistant membrane rafts from rod outer segment disk membranes. J Biol Chem 2002; 277:41843-9. [PMID: 12196538 PMCID: PMC4732712 DOI: 10.1074/jbc.m207111200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This study reports the isolation and characterization of a Triton X-100-resistant membrane fraction from homogenates of rod outer segment (ROS) disk membranes purified free of the surrounding plasma membrane. A portion of the ROS disk membrane was found to be resistant to Triton X-100 extraction at 4 degrees C. This detergent-resistant fraction was isolated as a low buoyant density band on sucrose density gradients and exhibited an increase in light scattering detected at 600 nm. Biochemical analysis of the Triton X-100-resistant fraction showed it to be enriched in cholesterol and sphingomyelin relative to phospholipid and in phospholipid relative to protein compared with the soluble fraction. The Triton X-100-resistant membranes described herein did not arise simply from partial solubilization of the ROS disk membranes because detergent-treated low buoyant density fractions isolated from homogenates with octyl glucopyranoside had cholesterol and sphingomyelin content indistinguishable from that of solubilized ROS disk homogenates. Analysis of proteins associated with the Triton X-100-resistant fraction showed it to be enriched in the rim-specific protein ROM-1 and caveolin; surprisingly, the fusion protein peripherin/rds (where rds is retinal degeneration slow), also localized to the disk rim, was entirely absent from the membrane raft domain. The lipid profiles of the Triton X-100-resistant membranes were virtually identical in preparations homogenized in either the light or dark. Slightly more ROM-1 was recovered from samples prepared in the light (23%) than from samples prepared in the dark (13%), but peripherin/rds could not be detected in either preparation. When the Triton X-100-resistant membranes were treated with methyl-beta-cyclodextran to deplete membrane cholesterol, the resultant membranes contained slightly lower levels of ROM-1, specifically in the dimeric form. Cholesterol depletion also resulted in the collapse of the large caveolin complex to monomeric caveolae. The results presented herein characterize a pool of ROM-1, a photoreceptor tetraspanin protein, that may play a regulatory role in peripherin/rds-dependent fusion.
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Affiliation(s)
- Kathleen Boesze-Battaglia
- Department of Molecular Biology, School of Osteopathic Medicine, University of Medicine and Dentistry of New Jersey, Stratford 08084, USA.
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Kong F, Guo X, Noel JG, Wells DA, Lovell GJ, Ogle CK. Thermal injury-induced increases of hepatocyte SOCS3 lead to decreases in STAT3. Shock 2002; 18:374-9. [PMID: 12392283 DOI: 10.1097/00024382-200210000-00014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Previous work in this laboratory has shown an increase of both mRNA and protein for suppressor of cytokine signaling 3 (SOCS3) in rat liver after thermal injury. This study identifies which liver cell type (parenchymal or non-parenchymal) is responsible for the postburn increase in SOCS3 and how this increase is connected to the signal transducer and activator of transcription (STAT) pathway. Parenchymal (hepatocytes) and non-parenchymal cells were isolated by Liberase digestion from postburn day 1 (PBD1) rats (including sham controls) and were analyzed for the expression of SOCS3 mRNA and protein and STAT3 and p-STAT3 protein. Reverse transcriptase (RT)-PCR performed on the isolated cells showed a significant increase of SOCS3 in the hepatocytes, but not in the non-parenchymal cells. When isolated hepatocytes from rats and the human hepatocyte cell line, HepG2, were cultured in the presence of IL-6, both showed an increase in SOCS3 mRNA expression. Anti-SOCS3, anti-STAT3, and anti-phosphorylated STAT3 labeling in both postburn rat liver and isolated hepatocyte cells that were cultured in the presence of IL-6 revealed that an increase in SOCS3 protein was accompanied by decrease in STAT3 protein. We propose that thermal injury stimulates non-parenchymal cells to produce cytokines, including IL-6, which in tum stimulate the Jak/STAT pathway in hepatocytes. The signal transduction pathway triggered by non-parenchymal cells causes an increase in SOCS3 production, which in turn induces the reduction of STAT3 protein in the hepatocytes.
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Affiliation(s)
- Fansheng Kong
- Department of Surgery, University of Cincinnati, Ohio 45229, USA
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Muller-Weeks S, Boesze-Battaglia K, Fitzgerald C. Deletional analysis of the rod photoreceptor cell peripherin/RDS carboxy-terminal region. Exp Eye Res 2002; 75:143-54. [PMID: 12137760 PMCID: PMC4746731 DOI: 10.1006/exer.2002.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The C-terminal region of peripherin/rds contains three predicted alpha-helical domains. One of these domains, corresponding to amino acids 311-322, form an amphiphilic alpha-helix previously shown to promote membrane fusion. The present studies were conducted to determine how the additional alpha-helical regions of the peripherin/rds C-terminus affect complex formation with rom-1, glycosylation, intracellular localization and membrane fusion properties. Bovine peripherin/rds and rom-1 were epitope tagged with an amino-terminal FLAG-tag or amino-terminal hemagglutinin (HA)-tag, respectively, and cloned into the pCI-neo expression vector for transient transfection into COS cells. Similarly, four C-terminal peripherin/rds truncation mutants (Delta1, Delta2, Delta3 and Delta4), corresponding to deletions of -19, -29, -39 and -59 amino acids were designed to disrupt the alpha-helical domains. Immunofluorescence microscopy and enzymatic digestions demonstrated that full-length peripherin/rds and the four C-terminal deletion mutants were localized to intracellular membranes and were all Endo-H sensitive. Western blotting and immunoprecipitation studies showed that the FLAG-tagged bovine peripherin/rds (full-length) was expressed as a 76kDa dimer, which associates with HA-tagged rom-1 to form a higher order complex. The deletion mutants were also able to associate with rom-1. However, when analyzed using non-denaturing tricine electrophoresis, full-length peripherin/rds and the Delta1, Delta2 and Delta3 mutants formed homo-oligomeric complexes, while the Delta4 mutant appeared to form only homodimers suggesting a region upstream of amino acid 300 may be involved in C-terminal interactions. Membrane fusion was then evaluated using fluorescence resonance energy transfer (RET) techniques. Intracellular COS cell membranes containing full-length peripherin/rds fused with rod outer segment plasma membrane vesicles. This fusion was inhibited with the addition of a synthetic peptide (PP-5) corresponding to the fusion domain of peripherin/rds. In contrast, fusion was negligible with any of the C-terminal truncation mutants. Collectively, these results suggest that in addition to the fusion domain, other regions of the peripherin/rds C-terminus are required for fusion. Most interesting is the observation that the last 19amino acids, a region downstream of the fusion peptide that is deleted in the Delta1 mutant, appear to be necessary for fusion. This region corresponds to the epitope for anti-peripherin/rds monoclonal antibody 2B6, which is shown to partially inhibit peripherin/rds mediated membrane fusion.
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Affiliation(s)
- Susan Muller-Weeks
- Department of Molecular Biology, University of Medicine and Dentistry of New Jersey--School of Osteopathic Medicine and UMDNJ-GSBS-Stratford Division, 2 Medical Center Drive, Stratford, NJ 08084, USA.
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Boesze-Battagliaa K, Stefano FP. Peripherin/rds fusogenic function correlates with subunit assembly. Exp Eye Res 2002; 75:227-31. [PMID: 12137768 DOI: 10.1006/exer.2002.2004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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STEFANO FRANKP, KROUSE JENNIFER, MARTA PETER, BOESZE-BATTAGLIA KATHLEEN. Heterologous expression of WT and mutant photoreceptor peripherin/rds in Madin Darby canine kidney cells: an assessment of fusogenic function. Exp Eye Res 2002; 74:267-83. [PMID: 11950237 PMCID: PMC4746730 DOI: 10.1006/exer.2001.1119] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Peripherin/rds is proposed to function as a fusion protein within the rod outer segment and a fusion domain has been mapped to amino acids 311-325 within the C-terminus. To map regions within peripherin/rds required for membrane fusion a series of C-terminal mutants was analyzed. Madin Darby canine kidney cells were transiently transfected with an Xpress or FLAG epitope tagged peripherin/rds (wt) and three mutants of peripherin/rds. The mutants selected were a P296T mutant (replacement of the proline at position 296 with a threonine) and two C-terminal deletion mutants (one lacking the terminal 10 amino acids, Delta10 and one lacking the terminal 50 amino acids, Delta50). The wt protein, the P296T and Delta10 mutants were detected on SDS-PAGE as 84 kDa dimers, that resolved into 38-42 kDa monomers under reducing conditions. The Delta50 mutant showed a slightly increased mobility. The cellular localization of mutants differed from that of wt peripherin/rds. The wt Xpress-human and wt FLAG-bovine peripherin/rds were localized to both intracellular and plasma membranes. In contrast, the C-terminal deletion mutants were localized only to the intracellular membrane. The P296T mutant presented a still different pattern: initially the protein localized to intracellular membranes. Upon confluence, however, the localization appeared to become predominantly plasma membrane. To assess the fusion activity of the proteins, the cell membranes were fractionated using sucrose density gradient centrifugation and the various fractions identified based on immunoreactivity in Western blot analysis with Golgi (anti-rab 6) or plasma membrane (anti-ZO-3) specific marker proteins. All membrane fractions were assayed for fusion with ROS plasma membrane vesicles. The plasma membrane enriched fractions (isolated at densities of 1.08 and 1.125 g ml(-1)) containing tagged peripherin/rds and the Delta10 mutant promoted membrane fusion with ROS plasma membrane vesicles. In contrast, fusion was not detected with plasma membrane vesicles from mock-transfected cells or the Delta50 peripherin/rds deletion mutant. Fusion was enhanced in a less dense fraction enriched in the P296T mutant (isolated from the 1.04/1.02 interface) relative to wt. Fusion was dependent on the presence of peripherin/rds in the membranes and could be inhibited with trypsinolysis and competition studies with the bovine fusion peptide, PP-5. Peptide competition suggests that the fusion domain of human peripherin/rds is most likely identical to that characterized in bovine and corresponds to amino acid residues 312-326. The C-terminal deletion mutants have allowed us to predict the minimal region of the C-terminus necessary for fusion to include residues starting at number 335. In addition a second region important in the formation of a fusion competent peripherin/rds has been mapped to a region upstream of the fusion peptide domain.
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Affiliation(s)
| | | | | | - KATHLEEN BOESZE-BATTAGLIA
- Address correspondence to: Kathleen Boesze-Battaglia, Department of Molecular Biology, UMDNJ-SOM, 2 Medical Center Drive, Stratford, NJ 08084, U.S.A.
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Boesze-Battaglia K, Goldberg AFX. Photoreceptor renewal: a role for peripherin/rds. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 217:183-225. [PMID: 12019563 PMCID: PMC4732730 DOI: 10.1016/s0074-7696(02)17015-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Visual transduction begins with the detection of light within the photoreceptor cell layer of the retina. Within this layer, specialized cells, termed rods and cones, contain the proteins responsible for light capture and its transduction to nerve impulses. The phototransductive proteins reside within an outer segment region that is connected to an inner segment by a thin stalk rich in cytoskeletal elements. A unique property of the outer segments is the presence of an elaborate intracellular membrane system that holds the phototransduction proteins and provides the requisite lipid environment. The maintenance of normal physiological function requires that these postmitotic cells retain the unique structure of the outer segment regions--stacks of membrane saccules in the case of rods and a continuous infolding of membrane in the case of cones. Both photoreceptor rod and cone cells achieve this through a series of coordinated steps. As new membranous material is synthesized, transported, and incorporated into newly forming outer segment membranes, a compensatory shedding of older membranous material occurs, thereby maintaining the segment at a constant length. These processes are collectively referred to as ROS (rod outer segment) or COS (cone outer segment) renewal. We review the cellular and molecular events responsible for these renewal processes and present the recent but compelling evidence, drawn from molecular genetic, biochemical, and biophysical approaches, pointing to an essential role for a unique tetraspanning membrane protein, called peripherin/rds, in the processes of disk morphogenesis.
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Affiliation(s)
- Kathleen Boesze-Battaglia
- School of Osteopathic Medicine, University of Medicine and Dentistry of New Jersey, Stratford 08084, USA
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The Complex of cGMP-Gated Channel and Na+/ Ca2+K+Exchanger in Rod Photoreceptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002. [DOI: 10.1007/978-1-4615-0121-3_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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Giusto NM, Pasquaré SJ, Salvador GA, Castagnet PI, Roque ME, Ilincheta de Boschero MG. Lipid metabolism in vertebrate retinal rod outer segments. Prog Lipid Res 2000; 39:315-91. [PMID: 10856601 DOI: 10.1016/s0163-7827(00)00009-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- N M Giusto
- Instituto de Investigaciones Bioquímicas, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, CC 857, B 8000 FWB, Bahia Blanca, Argentina.
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Boesze-Battaglia K, Stefano FP, Fenner M, Napoli AA. A peptide analogue to a fusion domain within photoreceptor peripherin/rds promotes membrane adhesion and depolarization. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1463:343-54. [PMID: 10675512 PMCID: PMC4732729 DOI: 10.1016/s0005-2736(99)00226-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Photoreceptor peripherin/rds promotes membrane fusion, through a putative fusion domain located within the C-terminus (Boesze-Battaglia et al., Biochemistry 37 (1998) 9477-9487). A peptide analogue to this region, PP-5, competitively inhibits peripherin/rds mediated fusion in a cell free assay system. To characterize how this region is involved in the fusion process we investigated two of the individual steps in membrane fusion, membrane adhesion and membrane destabilization inferred from depolarization studies. Membrane depolarization was measured as the collapse of a valinomycin induced K(+) diffusion potential in model membranes, using a potential sensitive fluorescent probe, diS-C(2)-5. PP-5 induced membrane depolarization in a concentration dependent manner. PP-5 has been shown by Fourier transform infrared spectroscopy to be an amphiphilic alpha-helix. Therefore, the requirement for an amphiphilic alpha-helix to promote depolarization was tested using two mutant peptides designed to disrupt either the amphiphilic nature of PP-5 (PP-5AB) or the alpha-helical structure (PP-5HB). PP-5AB inhibited PP-5 induced depolarization when added in an equimolar ratio to PP-5. Neither mutant peptide alone or in combination with PP-5 had any effect on calcium dependent vesicle aggregation. Using non-denaturing gel electrophoresis and size exclusion chromatography techniques PP-5 was shown to form a tetrameric complex. Equimolar mixtures of PP-5 and PP-5AB formed a heterotetramer which was unable to promote membrane depolarization. The hypothesis that PP-5 tetramers promote membrane depolarization is consistent with the calculated Hill coefficient of 3.725, determined from a Hill analysis of the depolarization data.
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Affiliation(s)
- K Boesze-Battaglia
- Department of Molecular Biology, University of Medicine and Dentistry of New Jersey-SOM, 2 Medical Center Drive, Stratford, NJ 08084, USA.
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Boesze-Battaglia K. Fusion between retinal rod outer segment membranes and model membranes: functional assays and role for peripherin/rds. Methods Enzymol 2000; 316:65-86. [PMID: 10800669 PMCID: PMC4732714 DOI: 10.1016/s0076-6879(00)16717-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- K Boesze-Battaglia
- Department of Molecular Biology, School of Osteopathic Medicine, University of Medicine and Dentistry of New Jersey, Stratford 08084, USA
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Tachibana I, Hemler ME. Role of transmembrane 4 superfamily (TM4SF) proteins CD9 and CD81 in muscle cell fusion and myotube maintenance. J Cell Biol 1999; 146:893-904. [PMID: 10459022 PMCID: PMC2156130 DOI: 10.1083/jcb.146.4.893] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/1999] [Accepted: 07/14/1999] [Indexed: 12/18/2022] Open
Abstract
The role of transmembrane 4 superfamily (TM4SF) proteins during muscle cell fusion has not been investigated previously. Here we show that the appearance of TM4SF protein, CD9, and the formation of CD9-beta1 integrin complexes were both regulated in coordination with murine C2C12 myoblast cell differentiation. Also, anti-CD9 and anti-CD81 monoclonal antibodies substantially inhibited and delayed conversion of C2C12 cells to elongated myotubes, without affecting muscle-specific protein expression. Studies of the human myoblast-derived RD sarcoma cell line further demonstrated that TM4SF proteins have a role during muscle cell fusion. Ectopic expression of CD9 caused a four- to eightfold increase in RD cell syncytia formation, whereas anti-CD9 and anti-CD81 antibodies markedly delayed RD syncytia formation. Finally, anti-CD9 and anti-CD81 monoclonal antibodies triggered apoptotic degeneration of C2C12 cell myotubes after they were formed. In summary, TM4SF proteins such as CD9 and CD81 appear to promote muscle cell fusion and support myotube maintenance.
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Affiliation(s)
- Isao Tachibana
- Dana-Farber Cancer Institute, and Harvard Medical School, Boston, Massachusetts 02115
| | - Martin E. Hemler
- Dana-Farber Cancer Institute, and Harvard Medical School, Boston, Massachusetts 02115
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Abstract
Two types of Usher syndrome, a blindness-deafness disorder, result from mutations in the myosin VIIa gene. As for most other unconventional myosins, little is known about the function or functions of myosin VIIa. Here, we studied the photoreceptor cells of mice with mutant myosin VIIa by electron immunomicroscopy and microscopic autoradiography. We found evidence that myosin VIIa functions in the connecting cilium of each photoreceptor cell and participates in the transport of opsin through this structure. These findings provide the first direct evidence that opsin travels along the connecting cilium en route to the outer segment. They demonstrate that a myosin may function in a cilium and suggest that abnormal opsin transport might contribute to blindness in Usher syndrome.
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Otto-Bruc AE, Fariss RN, Van Hooser JP, Palczewski K. Phosphorylation of photolyzed rhodopsin is calcium-insensitive in retina permeabilized by alpha-toxin. Proc Natl Acad Sci U S A 1998; 95:15014-9. [PMID: 9844007 PMCID: PMC24567 DOI: 10.1073/pnas.95.25.15014] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/1998] [Indexed: 11/18/2022] Open
Abstract
Light triggers the phototransduction cascade by activating the visual pigment rhodopsin (Rho --> Rho*). Phosphorylation of Rho* by rhodopsin kinase (RK) is necessary for the fast recovery of sensitivity after intense illumination. Ca2+ ions, acting through Ca2+-binding proteins, have been implicated in the desensitization of phototransduction. One such protein, recoverin, has been proposed to regulate RK activity contributing to adaptation to background illumination in retinal photoreceptor cells. In this report, we describe an in vitro assay system using isolated retinas that is well suited for a variety of biochemical assays, including assessing Ca2+ effects on Rho* phosphorylation. Pieces of bovine retina with intact rod outer segments were treated with pore-forming staphylococcal alpha-toxin, including an alpha-toxin mutant that forms pores whose permeability is modulated by Zn2+. The pores formed through the plasma membranes of rod cells permit the diffusion of small molecules <2 kDa but prevent the loss of proteins, including recoverin (25 kDa). The selective permeability of these pores was confirmed by using the small intracellular tracer N-(2-aminoethyl) biotinamide hydrochloride. Application of [gamma-32P]ATP to alpha-toxin-treated, isolated retina allowed us to monitor and quantify phosphorylation of Rho*. Under various experimental conditions, including low and high [Ca2+]free, the same level of Rho* phosphorylation was measured. No differences were observed between low and high [Ca2+]free conditions, even when rods were loaded with ATP and the pores were closed by Zn2+. These results suggest that under physiological conditions, Rho* phosphorylation is insensitive to regulation by Ca2+ and Ca2+-binding proteins, including recoverin.
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Affiliation(s)
- A E Otto-Bruc
- Department of Ophthalmology, University of Washington, Seattle, WA 98195-6485, USA
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Udovichenko IP, Newton AC, Williams DS. Regulation of the phosphorylation state of rhodopsin by dopamine. J Biol Chem 1998; 273:7181-4. [PMID: 9516406 DOI: 10.1074/jbc.273.13.7181] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are regulated by kinases and phosphatases that control their phosphorylation state. Here, the possibility that the state of GPCR phosphorylation could be affected by paracrine input was explored. We show that dopamine increased the rate of dephosphorylation of rhodopsin, the light receptor, in intact frog retinas. Further, we found that rod outer segments from dopamine-treated retinas contained increased rhodopsin phosphatase activity, indicating that this effect of dopamine on rhodopsin was mediated by stimulation of rhodopsin phosphatase. Dopamine is a ubiquitous neuromodulator and, in the retina, is released from the inner cell layers. Thus, our results identify a pathway for feedback regulation of rhodopsin from the inner retina and illustrate the involvement of dopamine in paracrine regulation of the sensitivity of a GPCR.
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Affiliation(s)
- I P Udovichenko
- Department of Pharmacology, University of California at San Diego School of Medicine, La Jolla, California 92093-0983, USA
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