1
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Carpineto P, Licata AM, Ciancaglini M. Proliferative Vitreoretinopathy: A Reappraisal. J Clin Med 2023; 12:5287. [PMID: 37629329 PMCID: PMC10455099 DOI: 10.3390/jcm12165287] [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: 06/15/2023] [Revised: 07/31/2023] [Accepted: 08/10/2023] [Indexed: 08/27/2023] Open
Abstract
Proliferative vitreoretinopathy (PVR) remains the main cause of failure after retinal detachment (RD) surgery. Despite the development of modern technologies and sophisticated techniques for the management of RD, the growth of fibrocellular membranes within the vitreous cavity and on both sides of the retinal surface, as well as intraretinal fibrosis, can compromise surgical outcomes. Since 1983, when the term PVR was coined by the Retina Society, a lot of knowledge has been obtained about the physiopathology and risk factors of PVR, but, despite the proposal of a lot of therapeutic challenges, surgical skills seem to be the only effective way to manage PVR complications.
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Affiliation(s)
- Paolo Carpineto
- Department of Medical, Oral and Biotechnological Sciences, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy;
| | - Arturo Maria Licata
- Department of Medical, Oral and Biotechnological Sciences, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy;
| | - Marco Ciancaglini
- Department of Clinical Medicine, Public Health, Life and Environmental Sciences, University of L’Aquila, 67100 L’Aquila, Italy;
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2
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Gelat B, Rathaur P, Malaviya P, Patel B, Trivedi K, Johar K, Gelat R. The intervention of epithelial-mesenchymal transition in homeostasis of human retinal pigment epithelial cells: a review. J Histotechnol 2022; 45:148-160. [DOI: 10.1080/01478885.2022.2137665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Brijesh Gelat
- Department of Zoology, BMTC and Human Genetics, School of Sciences, Gujarat University, Ahmedabad, India
| | - Pooja Rathaur
- Department of Cell and Molecular Biology, Iladevi Cataract and IOL Research Centre, Ahmedabad, Gujarat, India
| | - Pooja Malaviya
- Department of Cell and Molecular Biology, Iladevi Cataract and IOL Research Centre, Ahmedabad, Gujarat, India
| | - Binita Patel
- Department of Life Science, School of Sciences, Gujarat University, Ahmedabad, India
| | - Krupali Trivedi
- Department of Zoology, BMTC and Human Genetics, School of Sciences, Gujarat University, Ahmedabad, India
| | - Kaid Johar
- Department of Zoology, BMTC and Human Genetics, School of Sciences, Gujarat University, Ahmedabad, India
| | - Rahul Gelat
- Institute of Teaching and Research in Ayurveda (ITRA), Gujarat Ayurved University, Jamnagar, India
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3
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Wray S, Prendergast C, Arrowsmith S. Calcium-Activated Chloride Channels in Myometrial and Vascular Smooth Muscle. Front Physiol 2021; 12:751008. [PMID: 34867456 PMCID: PMC8637852 DOI: 10.3389/fphys.2021.751008] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/24/2021] [Indexed: 11/24/2022] Open
Abstract
In smooth muscle tissues, calcium-activated chloride channels (CaCC) provide the major anionic channel. Opening of these channels leads to chloride efflux and depolarization of the myocyte membrane. In this way, activation of the channels by a rise of intracellular [Ca2+], from a variety of sources, produces increased excitability and can initiate action potentials and contraction or increased tone. We now have a good mechanistic understanding of how the channels are activated and regulated, due to identification of TMEM16A (ANO1) as the molecular entity of the channel, but key questions remain. In reviewing these channels and comparing two distinct smooth muscles, myometrial and vascular, we expose the differences that occur in their activation mechanisms, properties, and control. We find that the myometrium only expresses “classical,” Ca2+-activated, and voltage sensitive channels, whereas both tonic and phasic blood vessels express classical, and non-classical, cGMP-regulated CaCC, which are voltage insensitive. This translates to more complex activation and regulation in vascular smooth muscles, irrespective of whether they are tonic or phasic. We therefore tentatively conclude that although these channels are expressed and functionally important in all smooth muscles, they are probably not part of the mechanisms governing phasic activity. Recent knockdown studies have produced unexpected functional results, e.g. no effects on labour and delivery, and tone increasing in some but decreasing in other vascular beds, strongly suggesting that there is still much to be explored concerning CaCC in smooth muscle.
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Affiliation(s)
- Susan Wray
- Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Clodagh Prendergast
- Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Sarah Arrowsmith
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
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4
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Kittredge A, Zhang Y, Yang T. Evaluating BEST1 mutations in pluripotent stem cell-derived retinal pigment epithelial cells. Methods Enzymol 2021; 654:365-382. [PMID: 34120722 PMCID: PMC9801436 DOI: 10.1016/bs.mie.2021.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Bestrophin-1 (BEST1) is a calcium-activated chloride channel (CaCC) predominantly expressed at the basolateral membrane of the retinal pigment epithelium (RPE). Over 250 mutations in the BEST1 gene have been documented to cause at least five retinal degenerative disorders, commonly termed bestrophinopathies, to which no treatment is currently available. Therefore, understanding the influences of BEST1 disease-causing mutations on the physiological function of BEST1 in RPE is critical for deciphering the pathology of bestrophinopathies and developing therapeutic strategies for patients. However, this task has been impeded by the rarity of BEST1 mutations and limited accessibility to native human RPE cells. Here, we describe a pluripotent stem cell (PSC)-based pipeline for reproducibly generating RPE cells expressing endogenous or exogenous mutant BEST1, which provides us with a powerful "disease-in-a-dish" approach for studying BEST1 mutations in physiological environments.
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Affiliation(s)
- Alec Kittredge
- Department of Molecular Pharmacology and Therapeutics, Columbia University, New York, NY, United States
| | - Yu Zhang
- Department of Ophthalmology, Columbia University, New York, NY, United States,Corresponding authors: ; ;
| | - Tingting Yang
- Department of Ophthalmology, Columbia University, New York, NY, United States,Corresponding authors: ; ;
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5
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Zhou M, Geathers JS, Grillo SL, Weber SR, Wang W, Zhao Y, Sundstrom JM. Role of Epithelial-Mesenchymal Transition in Retinal Pigment Epithelium Dysfunction. Front Cell Dev Biol 2020; 8:501. [PMID: 32671066 PMCID: PMC7329994 DOI: 10.3389/fcell.2020.00501] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/26/2020] [Indexed: 12/14/2022] Open
Abstract
Retinal pigment epithelial (RPE) cells maintain the health and functional integrity of both photoreceptors and the choroidal vasculature. Loss of RPE differentiation has long been known to play a critical role in numerous retinal diseases, including inherited rod-cone degenerations, inherited macular degeneration, age-related macular degeneration, and proliferative vitreoretinopathy. Recent studies in post-mortem eyes have found upregulation of critical epithelial-mesenchymal transition (EMT) drivers such as TGF-β, Wnt, and Hippo. As RPE cells become less differentiated, they begin to exhibit the defining characteristics of mesenchymal cells, namely, the capacity to migrate and proliferate. A number of preclinical studies, including animal and cell culture experiments, also have shown that RPE cells undergo EMT. Taken together, these data suggest that RPE cells retain the reprogramming capacity to move along a continuum between polarized epithelial cells and mesenchymal cells. We propose that movement along this continuum toward a mesenchymal phenotype be defined as RPE Dysfunction. Potential mechanisms include impaired tight junctions, accumulation of misfolded proteins and dysregulation of several key pathways and molecules, such as TGF-β pathway, Wnt pathway, nicotinamide, microRNA 204/211 and extracellular vesicles. This review synthesizes the evidence implicating EMT of RPE cells in post-mortem eyes, animal studies, primary RPE, iPSC-RPE and ARPE-19 cell lines.
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Affiliation(s)
- Mi Zhou
- Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, United States
| | - Jasmine S Geathers
- Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, United States
| | - Stephanie L Grillo
- Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, United States
| | - Sarah R Weber
- Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, United States
| | - Weiwei Wang
- Department of Medicine, The University of Texas Health Science Center at San Antonio, Houston, TX, United States
| | - Yuanjun Zhao
- Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, United States
| | - Jeffrey M Sundstrom
- Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, United States
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6
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Cordes M, Bucichowski P, Alfaar AS, Tsang SH, Almedawar S, Reichhart N, Strauß O. Inhibition of Ca 2+ channel surface expression by mutant bestrophin-1 in RPE cells. FASEB J 2020; 34:4055-4071. [PMID: 31930599 DOI: 10.1096/fj.201901202rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 12/09/2019] [Accepted: 12/31/2019] [Indexed: 01/11/2023]
Abstract
The BEST1 gene product bestrophin-1, a Ca2+ -dependent anion channel, interacts with CaV 1.3 Ca2+ channels in the retinal pigment epithelium (RPE). BEST1 mutations lead to Best vitelliform macular dystrophy. A common functional defect of these mutations is reduced trafficking of bestrophin-1 into the plasma membrane. We hypothesized that this defect affects the interaction partner CaV 1.3 channel affecting Ca2+ signaling and altered RPE function. Thus, we investigated the protein interaction between CaV 1.3 channels and bestrophin-1 by immunoprecipitation, CaV 1.3 activity in the presence of mutant bestrophin-1 and intracellular trafficking of the interaction partners in confluent RPE monolayers. We selected four BEST1 mutations, each representing one mutational hotspot of the disease: T6P, F80L, R218C, and F305S. Heterologously expressed L-type channels and mutant bestrophin-1 showed reduced interaction, reduced CaV 1.3 channel activity, and changes in surface expression. Transfection of polarized RPE (porcine primary cells, iPSC-RPE) that endogenously express CaV 1.3 and wild-type bestrophin-1, with mutant bestrophin-1 confirmed reduction of CaV 1.3 surface expression. For the four selected BEST1 mutations, presence of mutant bestrophin-1 led to reduced CaV 1.3 activity by modulating pore-function or decreasing surface expression. Reduced CaV 1.3 activity might open new ways to understand symptoms of Best vitelliform macular dystrophy such as reduced electro-oculogram, lipofuscin accumulation, and vision impairment.
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Affiliation(s)
- Magdalena Cordes
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
| | - Piotr Bucichowski
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
| | - Ahmad S Alfaar
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
| | - Stephen H Tsang
- Jonas Children's Vision Care, and Bernard & Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia Stem Cell Initiative, Departments of Ophthalmology Pathology & Cell Biology, Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
| | - Seba Almedawar
- Center for Molecular and Cellular Bioengineering (CMCB), Center for Regenerative Therapies, Dresden (CRTD), Technische Universität Dresden, Dresden, Germany
| | - Nadine Reichhart
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
| | - Olaf Strauß
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
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7
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Jaffal L, Joumaa WH, Assi A, Helou C, Condroyer C, El Dor M, Cherfan G, Zeitz C, Audo I, Zibara K, El Shamieh S. Novel Missense Mutations in BEST1 Are Associated with Bestrophinopathies in Lebanese Patients. Genes (Basel) 2019; 10:genes10020151. [PMID: 30781664 PMCID: PMC6409913 DOI: 10.3390/genes10020151] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/07/2019] [Accepted: 02/07/2019] [Indexed: 12/25/2022] Open
Abstract
To identify Bestrophin 1 (BEST1) causative mutations in six Lebanese patients from three families, of whom four had a presumed clinical diagnosis of autosomal recessive bestrophinopathy (ARB) and two showed a phenotype with a single vitelliform lesion, patients were subjected to standard ophthalmic examinations. In addition, BEST1 exons and their flanking regions were amplified and sequenced by Sanger sequencing. Co-segregation and detailed bio-informatic analyses were performed. Clinical examination results were consistent with ARB diagnosis for all index patients showing multifocal vitelliform lesions and a markedly reduced light peak in the electrooculogram, including the two patients with a single vitelliform lesion. In all cases, most likely disease-causing BEST1 mutations co-segregated with the phenotype. The ARB cases showed homozygous missense variants (M1, c.209A>G, p.(Asp70Gly) in exon 3, M2, c.1403C>T; p.(Pro468Leu) in exon 10 and M3, c.830C>T, p.(Thr277Met) in exon 7), while the two patients with a single vitelliform lesion were compound heterozygous for M1 and M2. To our knowledge, this is the first study describing mutations in Lebanese patients with bestrophinopathy, where novel biallelic BEST1 mutations associated with two phenotypes were identified. Homozygous mutations were associated with multifocal lesions, subretinal fluid, and intraretinal cysts, whereas compound heterozygous ones were responsible for a single macular vitelliform lesion.
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Affiliation(s)
- Lama Jaffal
- Department of Biological and Environmental Sciences, Faculty of Science, Beirut Arab University, Debbieh 1107 2809, Lebanon.
| | - Wissam H Joumaa
- Rammal Hassan Rammal Research Laboratory, PhyToxE research group, Department of Life and Earth Sciences, Faculty of Sciences, Lebanese University, Nabatieh 1700, Lebanon.
| | - Alexandre Assi
- Retinal Service, Beirut Eye & ENT Specialist Hospital, Beirut 1106, Lebanon.
| | - Charles Helou
- Retinal Service, Beirut Eye & ENT Specialist Hospital, Beirut 1106, Lebanon.
| | - Christel Condroyer
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - Maya El Dor
- Biology Department, Faculty of Sciences-I, Lebanese University, Beirut, Lebanon.
| | - Georges Cherfan
- Retinal Service, Beirut Eye & ENT Specialist Hospital, Beirut 1106, Lebanon.
| | - Christina Zeitz
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC1423, F-75012 Paris, France.
- University College London Institute of Ophthalmology, London EC1V 9EL, UK.
| | - Kazem Zibara
- Biology Department, Faculty of Sciences-I, Lebanese University, Beirut, Lebanon.
- ER045, PRASE, DSST, Lebanese University, Beirut, Lebanon.
| | - Said El Shamieh
- Rammal Hassan Rammal Research Laboratory, PhyToxE research group, Department of Life and Earth Sciences, Faculty of Sciences, Lebanese University, Nabatieh 1700, Lebanon.
- Department of Medical Laboratory Technology, Faculty of Health Sciences, Beirut Arab University, Beirut 1107 2809, Lebanon.
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8
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Korkka I, Viheriälä T, Juuti-Uusitalo K, Uusitalo-Järvinen H, Skottman H, Hyttinen J, Nymark S. Functional Voltage-Gated Calcium Channels Are Present in Human Embryonic Stem Cell-Derived Retinal Pigment Epithelium. Stem Cells Transl Med 2018; 8:179-193. [PMID: 30394009 PMCID: PMC6344904 DOI: 10.1002/sctm.18-0026] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 08/24/2018] [Accepted: 09/07/2018] [Indexed: 11/25/2022] Open
Abstract
Retinal pigment epithelium (RPE) performs important functions for the maintenance of photoreceptors and vision. Malfunctions within the RPE are implicated in several retinal diseases for which transplantations of stem cell‐derived RPE are promising treatment options. Their success, however, is largely dependent on the functionality of the transplanted cells. This requires correct cellular physiology, which is highly influenced by the various ion channels of RPE, including voltage‐gated Ca2+ (CaV) channels. This study investigated the localization and functionality of CaV channels in human embryonic stem cell (hESC)‐derived RPE. Whole‐cell patch‐clamp recordings from these cells revealed slowly inactivating L‐type currents comparable to freshly isolated mouse RPE. Some hESC‐RPE cells also carried fast transient T‐type resembling currents. These findings were confirmed by immunostainings from both hESC‐ and mouse RPE that showed the presence of the L‐type Ca2+ channels CaV1.2 and CaV1.3 as well as the T‐type Ca2+ channels CaV3.1 and CaV3.2. The localization of the major subtype, CaV1.3, changed during hESC‐RPE maturation co‐localizing with pericentrin to the base of the primary cilium before reaching more homogeneous membrane localization comparable to mouse RPE. Based on functional assessment, the L‐type Ca2+ channels participated in the regulation of vascular endothelial growth factor secretion as well as in the phagocytosis of photoreceptor outer segments in hESC‐RPE. Overall, this study demonstrates that a functional machinery of voltage‐gated Ca2+ channels is present in mature hESC‐RPE, which is promising for the success of transplantation therapies. stem cells translational medicine2019;8:179&15
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Affiliation(s)
- Iina Korkka
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
| | - Taina Viheriälä
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland.,Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere, Finland
| | - Kati Juuti-Uusitalo
- Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere, Finland
| | - Hannele Uusitalo-Järvinen
- Eye Centre, Tampere University Hospital, Tampere, Finland.,Faculty of Medicine and Life Sciences, Department of Ophthalmology, University of Tampere, Tampere, Finland
| | - Heli Skottman
- Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere, Finland
| | - Jari Hyttinen
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
| | - Soile Nymark
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
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9
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Marmorstein AD, Johnson AA, Bachman LA, Andrews-Pfannkoch C, Knudsen T, Gilles BJ, Hill M, Gandhi JK, Marmorstein LY, Pulido JS. Mutant Best1 Expression and Impaired Phagocytosis in an iPSC Model of Autosomal Recessive Bestrophinopathy. Sci Rep 2018. [PMID: 29540715 PMCID: PMC5852082 DOI: 10.1038/s41598-018-21651-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Autosomal recessive bestrophinopathy (ARB) is caused by mutations in the gene BEST1 which encodes bestrophin 1 (Best1), an anion channel expressed in retinal pigment epithelial (RPE) cells. It has been hypothesized that ARB represents the human null phenotype for BEST1 and that this occurs due to nonsense mediated decay (NMD). To test this hypothesis, we generated induced pluripotent stem cells (iPSCs) from a patient with ARB and her parents. After differentiation to retinal pigment epithelial (iPSC-RPE) cells, both BEST1 mRNA and Best1 protein expression were compared to controls. BEST1 mRNA expression levels, determined by quantitative PCR, were similar in ARB iPSC-RPE, parental cells, and genetically unrelated controls. Western blotting revealed that CRALBP and RPE65 were expressed within the range delineated by unrelated controls in iPSC-RPE from the ARB donor and her parents. Best1 protein was detected in different clones of ARB iPSC-RPE, but at reduced levels compared to all controls. When tested for the ability to phagocytose photoreceptor outer segments, ARB iPSC-RPE exhibited impaired internalization. These data suggest that impaired phagocytosis is a trait common to the bestrophinopathies. Furthermore, ARB is not universally the result of NMD and ARB, in this patient, is not due to the absence of Best1.
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Affiliation(s)
- Alan D Marmorstein
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
| | - Adiv A Johnson
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Lori A Bachman
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | | | - Travis Knudsen
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Benjamin J Gilles
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Matthew Hill
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Jarel K Gandhi
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Lihua Y Marmorstein
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Jose S Pulido
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
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10
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Johnson AA, Guziewicz KE, Lee CJ, Kalathur RC, Pulido JS, Marmorstein LY, Marmorstein AD. Bestrophin 1 and retinal disease. Prog Retin Eye Res 2017; 58:45-69. [PMID: 28153808 DOI: 10.1016/j.preteyeres.2017.01.006] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 01/23/2017] [Accepted: 01/25/2017] [Indexed: 12/18/2022]
Abstract
Mutations in the gene BEST1 are causally associated with as many as five clinically distinct retinal degenerative diseases, which are collectively referred to as the "bestrophinopathies". These five associated diseases are: Best vitelliform macular dystrophy, autosomal recessive bestrophinopathy, adult-onset vitelliform macular dystrophy, autosomal dominant vitreoretinochoroidopathy, and retinitis pigmentosa. The most common of these is Best vitelliform macular dystrophy. Bestrophin 1 (Best1), the protein encoded by the gene BEST1, has been the subject of a great deal of research since it was first identified nearly two decades ago. Today we know that Best1 functions as both a pentameric anion channel and a regulator of intracellular Ca2+ signaling. Best1 is an integral membrane protein which, within the eye, is uniquely expressed in the retinal pigment epithelium where it predominantly localizes to the basolateral plasma membrane. Within the brain, Best1 expression has been documented in both glial cells and astrocytes where it functions in both tonic GABA release and glutamate transport. The crystal structure of Best1 has revealed critical information about how Best1 functions as an ion channel and how Ca2+ regulates that function. Studies using animal models have led to critical insights into the physiological roles of Best1 and advances in stem cell technology have allowed for the development of patient-derived, "disease in a dish" models. In this article we review our knowledge of Best1 and discuss prospects for near-term clinical trials to test therapies for the bestrophinopathies, a currently incurable and untreatable set of diseases.
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Affiliation(s)
- Adiv A Johnson
- Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA; Nikon Instruments, Melville, NY, USA
| | - Karina E Guziewicz
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - C Justin Lee
- Center for Neuroscience and Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea
| | - Ravi C Kalathur
- New York Structural Biology Center, New York Consortium on Membrane Protein Structure, New York, NY, USA
| | - Jose S Pulido
- Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA
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11
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Keckeis S, Reichhart N, Roubeix C, Strauß O. Anoctamin2 (TMEM16B) forms the Ca2+-activated Cl− channel in the retinal pigment epithelium. Exp Eye Res 2017; 154:139-150. [DOI: 10.1016/j.exer.2016.12.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 12/05/2016] [Accepted: 12/05/2016] [Indexed: 01/12/2023]
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12
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Boedtkjer E, Matchkov VV, Boedtkjer DMB, Aalkjaer C. Negative News: Cl− and HCO3− in the Vascular Wall. Physiology (Bethesda) 2016; 31:370-83. [DOI: 10.1152/physiol.00001.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Cl− and HCO3− are the most prevalent membrane-permeable anions in the intra- and extracellular spaces of the vascular wall. Outwardly directed electrochemical gradients for Cl− and HCO3− permit anion channel opening to depolarize vascular smooth muscle and endothelial cells. Transporters and channels for Cl− and HCO3− also modify vascular contractility and structure independently of membrane potential. Transport of HCO3− regulates intracellular pH and thereby modifies the activity of enzymes, ion channels, and receptors. There is also evidence that Cl− and HCO3− transport proteins affect gene expression and protein trafficking. Considering the extensive implications of Cl− and HCO3− in the vascular wall, it is critical to understand how these ions are transported under physiological conditions and how disturbances in their transport can contribute to disease development. Recently, sensing mechanisms for Cl− and HCO3− have been identified in the vascular wall where they modify ion transport and vasomotor function, for instance, during metabolic disturbances. This review discusses current evidence that transport (e.g., via NKCC1, NBCn1, Ca2+-activated Cl− channels, volume-regulated anion channels, and CFTR) and sensing (e.g., via WNK and RPTPγ) of Cl− and HCO3− influence cardiovascular health and disease.
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Affiliation(s)
| | | | - Donna M. B. Boedtkjer
- Department of Biomedicine, Aarhus University, Denmark
- Department of Clinical Medicine, Aarhus University, Denmark; and
| | - Christian Aalkjaer
- Department of Biomedicine, Aarhus University, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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13
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Sung TS, O'Driscoll K, Zheng H, Yapp NJ, Leblanc N, Koh SD, Sanders KM. Influence of intracellular Ca2+ and alternative splicing on the pharmacological profile of ANO1 channels. Am J Physiol Cell Physiol 2016; 311:C437-51. [PMID: 27413167 DOI: 10.1152/ajpcell.00070.2016] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 07/09/2016] [Indexed: 11/22/2022]
Abstract
Anoctamin-1 (ANO1) is a Ca(2+)-activated Cl(-) channel expressed in many types of cells. Splice variants of ANO1 have been shown to influence the biophysical properties of conductance. It has been suggested that several new antagonists of ANO1 with relatively high affinity and selectivity might be useful for experimental and, potentially, therapeutic purposes. We investigated the effects of intracellular Ca(2+) concentration ([Ca(2+)]i) at 100-1,000 nM, a concentration range that might be achieved in cells during physiological activation of ANO1 channels, on blockade of ANO1 channels expressed in HEK-293 cells. Whole cell and excised patch configurations of the patch-clamp technique were used to perform tests on a variety of naturally occurring splice variants of ANO1. Blockade of ANO1 currents with aminophenylthiazole (T16Ainh-A01) was highly dependent on [Ca(2+)]i Increasing [Ca(2+)]i reduced the potency of this blocker. Similar Ca(2+)-dependent effects were also observed with benzbromarone. Experiments on excised, inside-out patches showed that the diminished potency of the blockers caused by intracellular Ca(2+) might involve a competitive interaction for a common binding site or repulsion of the blocking drugs by electrostatic forces at the cytoplasmic surface of the channels. The degree of interaction between the channel blockers and [Ca(2+)]i depends on the splice variant expressed. These experiments demonstrate that the efficacy of ANO1 antagonists depends on [Ca(2+)]i, suggesting a need for caution when ANO1 blockers are used to determine the role of ANO1 in physiological functions and in their use as therapeutic agents.
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Affiliation(s)
- Tae Sik Sung
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Kate O'Driscoll
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Haifeng Zheng
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Nicholas J Yapp
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Normand Leblanc
- Department of Pharmacology, Center for Cardiovascular Research, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
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14
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Protein partners of the calcium channel β subunit highlight new cellular functions. Biochem J 2016; 473:1831-44. [DOI: 10.1042/bcj20160125] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 03/15/2016] [Indexed: 12/21/2022]
Abstract
Calcium plays a key role in cell signalling by its intervention in a wide range of physiological processes. Its entry into cells occurs mainly via voltage-gated calcium channels (VGCC), which are found not only in the plasma membrane of excitable cells but also in cells insensitive to electrical signals. VGCC are composed of different subunits, α1, β, α2δ and γ, among which the cytosolic β subunit (Cavβ) controls the trafficking of the channel to the plasma membrane, its regulation and its gating properties. For many years, these were the main functions associated with Cavβ. However, a growing number of proteins have been found to interact with Cavβ, emphasizing the multifunctional role of this versatile protein. Interestingly, some of the newly assigned functions of Cavβ are independent of its role in the regulation of VGCC, and thus further increase its functional roles. Based on the identity of Cavβ protein partners, this review emphasizes the diverse cellular functions of Cavβ and summarizes both past findings as well as recent progress in the understanding of VGCC.
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15
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Strauß O, Reichhart N, Gomez NM, Müller C. Contribution of Ion Channels in Calcium Signaling Regulating Phagocytosis: MaxiK, Cav1.3 and Bestrophin-1. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:739-44. [PMID: 26427483 DOI: 10.1007/978-3-319-17121-0_98] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mutations in the BEST1 gene lead to a variety of retinal degenerations including Best's vitelliforme macular degeneration. The BEST1 gene product, bestrophin-1, is expressed in the retinal pigment epithelium (RPE). It is likely that mutant bestrophin-1 impairs functions of the RPE which support photoreceptor function and will thus lead to retinal degeneration. However, the RPE function which is influenced by bestrophin-1 is so far not identified. Previously we showed that bestrophin-1 interacts with L-type Ca²⁺ channels of the CaV1.3 subtype and that the endogenously expressed bestrophin-1 is required for intracellular Ca²⁺ regulation. A hallmark of Best's disease is the fast lipofuscin accumulation occurring already at young ages. Therefore, we addressed the hypothesis that bestrophin-1 might influence phagocytosis of photoreceptor outer segments (POS) by the RPE. Here, siRNA knock-down of bestrophin-1 expression as well as inhibition of L-type Ca²⁺ channel activity modulated the POS phagocytosis in vitro. In vivo CaV1.3 expression appeared to be diurnal regulated with a higher expression rate in the afternoon. Compared to wild-type littermates, Ca V 1.3 (-/-) mice showed a shift in the circadian POS phagocytosis with an increased activity in the afternoon. Thus we suggest that mutant bestrophin-1 leads to an impaired regulation of the POS phagocytosis by the RPE which would explain the fast lipofuscin accumulation in Best patients.
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Affiliation(s)
- Olaf Strauß
- Experimental Ophthalmology, Department of Ophthalmology, Charite University Medicine Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
| | - Nadine Reichhart
- Experimental Ophthalmology, Department of Ophthalmology, Charite University Medicine Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
| | - Nestor Mas Gomez
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania, Augustenburger Platz 1, 240 South 40th Street, 19104-6030, Philadelphia, PA, USA.
| | - Claudia Müller
- Department of Biological Sciences, Center for Cancer, Genetic Diseases and Gene Regulation, Fordham University Bronx, 10458, Bronx, NY, USA.
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16
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Giblin JP, Comes N, Strauss O, Gasull X. Ion Channels in the Eye: Involvement in Ocular Pathologies. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 104:157-231. [PMID: 27038375 DOI: 10.1016/bs.apcsb.2015.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The eye is the sensory organ of vision. There, the retina transforms photons into electrical signals that are sent to higher brain areas to produce visual sensations. In the light path to the retina, different types of cells and tissues are involved in maintaining the transparency of avascular structures like the cornea or lens, while others, like the retinal pigment epithelium, have a critical role in the maintenance of photoreceptor function by regenerating the visual pigment. Here, we have reviewed the roles of different ion channels expressed in ocular tissues (cornea, conjunctiva and neurons innervating the ocular surface, lens, retina, retinal pigment epithelium, and the inflow and outflow systems of the aqueous humor) that are involved in ocular disease pathophysiologies and those whose deletion or pharmacological modulation leads to specific diseases of the eye. These include pathologies such as retinitis pigmentosa, macular degeneration, achromatopsia, glaucoma, cataracts, dry eye, or keratoconjunctivitis among others. Several disease-associated ion channels are potential targets for pharmacological intervention or other therapeutic approaches, thus highlighting the importance of these channels in ocular physiology and pathophysiology.
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Affiliation(s)
- Jonathan P Giblin
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Nuria Comes
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | | | - Xavier Gasull
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
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17
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Johnson AA, Bachman LA, Gilles BJ, Cross SD, Stelzig KE, Resch ZT, Marmorstein LY, Pulido JS, Marmorstein AD. Autosomal Recessive Bestrophinopathy Is Not Associated With the Loss of Bestrophin-1 Anion Channel Function in a Patient With a Novel BEST1 Mutation. Invest Ophthalmol Vis Sci 2015. [PMID: 26200502 DOI: 10.1167/iovs.15-16910] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
PURPOSE Mutations in BEST1, encoding bestrophin-1 (Best1), cause autosomal recessive bestrophinopathy (ARB). Encoding bestrophin-1 is a pentameric anion channel localized to the basolateral plasma membrane of the RPE. Here, we characterize the effects of the mutations R141H (CGC > CAC) and I366fsX18 (c.1098_1100+7del), identified in a patient in our practice, on Best1 trafficking, oligomerization, and channel activity. METHODS Currents of Cl- were assessed in transfected HEK293 cells using whole-cell patch clamp. Best1 localization was assessed by confocal microscopy in differentiated, human-induced pluripotent stem cell-derived RPE (iPSC-RPE) cells following expression of mutants via adenovirus-mediated gene transfer. Oligomerization was evaluated by coimmunoprecipitation in iPSC-RPE and MDCK cells. RESULTS Compared to Best1, Best1 I366fsX18 currents were increased while Best1 R141H Cl- currents were diminished. Coexpression of Best1 R141H with Best1 or Best1 I366fsX18 resulted in rescued channel activity. Overexpressed Best1, Best1 R141H, and Best1 I366fsX18 were all properly localized in iPSC-RPE cells; Best1 R141H and Best1 I366fsX18 coimmunoprecipitated with endogenous Best1 in iPSC-RPE cells and with each other in MDCK cells. CONCLUSIONS The first 366 amino acids of Best1 are sufficient to mediate channel activity and homo-oligomerization. The combination of Best1 and Best1 R141H does not cause disease, while Best1 R141H together with Best1 I366fsX18 causes ARB. Since both combinations generate comparable Cl- currents, this indicates that ARB in this patient is not caused by a loss of channel activity. Moreover, Best1 I366fsX18 differs from Best1 in that it lacks most of the cytosolic C-terminal domain, suggesting that the loss of this region contributes significantly to the pathogenesis of ARB in this patient.
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Affiliation(s)
- Adiv A Johnson
- Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States
| | - Lori A Bachman
- Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States
| | - Benjamin J Gilles
- Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States
| | - Samuel D Cross
- Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States
| | - Kimberly E Stelzig
- Center for Regenerative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Zachary T Resch
- Center for Regenerative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Lihua Y Marmorstein
- Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States
| | - Jose S Pulido
- Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States 3Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Alan D Marmorstein
- Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States
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18
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Golubinskaya V, Elvin J, Ebefors K, Gustafsson H, Mallard C, Nyström J, Nilsson H. Bestrophin-3 is differently expressed in normal and injured mouse glomerular podocytes. Acta Physiol (Oxf) 2015; 214:481-96. [PMID: 25912364 DOI: 10.1111/apha.12516] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Revised: 03/17/2015] [Accepted: 04/20/2015] [Indexed: 12/13/2022]
Abstract
AIM Bestrophins are putative calcium-activated chloride channels. Recently, cell-protective functions for Bestrophin-3 (Best3) were proposed. Best3 exists in different splice variants. We have here examined expression, alternative splicing and localization of Best3 in mouse podocytes under normal conditions and during endoplasmic reticulum (ER) stress. METHODS Best3 expression was determined on the mRNA level using quantitative PCR and on the protein level by immunohistochemistry and Western blotting. RESULTS Staining for Best3 was pronounced in glomeruli and was detected in cultured mouse podocytes. Best3 did not co-localize with markers for endothelial cells (CD31), podocyte foot processes (synaptopodin) or microtubules (actin). However, immunogold-based electron microscopy and co-localization with nestin showed Best3 presence in podocyte primary processes and cell bodies. Only two splice variants of Best3 mRNA (both lacking exons 2 and 3, and one also lacking exon 6), but no full-length variant, were detected. ER stress induced by lipopolysaccharides in vivo transiently elevated mRNA levels of total Best3 and its two splice variants with different time courses. In cultured podocytes under ER stress induced by thapsigargin, the expression of total Best3, its splice variants and nestin transiently increased with similar time courses. The ER stress marker C/EBP homologous protein (CHOP) and nestin mRNA increased during ER stress in vivo and in vitro. CONCLUSIONS Best3 is localized intracellularly in cell bodies and primary processes of mouse podocytes and is co-localized with nestin. Two splice variants of Best3 are expressed in glomeruli and in cultured podocytes, and their expression is differentially regulated in ER stress.
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Affiliation(s)
- V. Golubinskaya
- Department of Physiology; Institute of Neuroscience and Physiology; The Sahlgrenska Academy at the University of Gothenburg; Gothenburg Sweden
| | - J. Elvin
- Department of Molecular and Clinical Medicine; Institute of Medicine; The Sahlgrenska Academy at the University of Gothenburg; Gothenburg Sweden
| | - K. Ebefors
- Department of Physiology; Institute of Neuroscience and Physiology; The Sahlgrenska Academy at the University of Gothenburg; Gothenburg Sweden
| | - H. Gustafsson
- Department of Physiology; Institute of Neuroscience and Physiology; The Sahlgrenska Academy at the University of Gothenburg; Gothenburg Sweden
| | - C. Mallard
- Department of Physiology; Institute of Neuroscience and Physiology; The Sahlgrenska Academy at the University of Gothenburg; Gothenburg Sweden
| | - J. Nyström
- Department of Physiology; Institute of Neuroscience and Physiology; The Sahlgrenska Academy at the University of Gothenburg; Gothenburg Sweden
| | - H. Nilsson
- Department of Physiology; Institute of Neuroscience and Physiology; The Sahlgrenska Academy at the University of Gothenburg; Gothenburg Sweden
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Reichhart N, Markowski M, Ishiyama S, Wagner A, Crespo-Garcia S, Schorb T, Ramalho JS, Milenkovic VM, Föckler R, Seabra MC, Strauß O. Rab27a GTPase modulates L-type Ca2+ channel function via interaction with the II-III linker of CaV1.3 subunit. Cell Signal 2015; 27:2231-40. [PMID: 26235199 DOI: 10.1016/j.cellsig.2015.07.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 07/28/2015] [Indexed: 12/31/2022]
Abstract
In a variety of cells, secretory processes require the activation of both Rab27a and L-type channels of the Ca(V)1.3 subtype. In the retinal pigment epithelium (RPE), Rab27a and Ca(V)1.3 channels regulate growth-factor secretion towards its basolateral side. Analysis of murine retina sections revealed a co-localization of both Rab27a and Ca(V)1.3 at the basolateral membrane of the RPE. Heterologously expressed Ca(V)1.3/β3/α2δ1 channels showed negatively shifted voltage-dependence and decreased current density of about 70% when co-expressed with Rab27a. However, co-localization analysis using α(5)β(1) integrin as a membrane marker revealed that Rab27a co-expression reduced the surface expression of Ca(V)1.3 only about 10%. Physical binding of heterologously expressed Rab27a with Ca(V)1.3 channels was shown by co-localization in immunocytochemistry as well as co-immunoprecipitation which was abolished after deletion of a MyRIP-homologous amino acid sequence at the II-III linker of the Ca(V)1.3 subunit. Rab27a over-expression in ARPE-19 cells positively shifted the voltage dependence, decreased current density of endogenous Ca(V)1.3 channels and reduced VEGF-A secretion. We show the first evidence of a direct functional modulation of an ion channel by Rab27a suggesting a new mechanism of Rab and ion channel interaction in the control of VEGF-A secretion in the RPE.
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Affiliation(s)
- Nadine Reichhart
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany; Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany
| | - Magdalena Markowski
- Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany
| | - Shimpei Ishiyama
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Andrea Wagner
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Sergio Crespo-Garcia
- Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany
| | - Talitha Schorb
- Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany
| | - José S Ramalho
- CEDOC, Faculdade de Ciências Médicas (FCM), Universidade Nova de Lisboa, Lisbon, Portugal
| | - Vladimir M Milenkovic
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany; Department of Psychiatry and Psychotherapy, Molecular Neuroscience, University of Regensburg, Germany
| | - Renate Föckler
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Miguel C Seabra
- CEDOC, Faculdade de Ciências Médicas (FCM), Universidade Nova de Lisboa, Lisbon, Portugal
| | - Olaf Strauß
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany; Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany.
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20
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Dam VS, Boedtkjer DMB, Aalkjaer C, Matchkov V. The bestrophin- and TMEM16A-associated Ca(2+)- activated Cl(–) channels in vascular smooth muscles. Channels (Austin) 2015; 8:361-9. [PMID: 25478625 PMCID: PMC4203738 DOI: 10.4161/chan.29531] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The presence of Ca2+-activated Cl– currents (ICl(Ca)) in vascular smooth muscle cells (VSMCs) is well established. ICl(Ca) are supposedly important for arterial contraction by linking changes in [Ca2+]i and membrane depolarization. Bestrophins and some members of the TMEM16 protein family were recently associated with ICl(Ca). Two distinct ICl(Ca) are characterized in VSMCs; the cGMP-dependent ICl(Ca) dependent upon bestrophin expression and the ‘classical’ Ca2+-activated Cl– current, which is bestrophin-independent. Interestingly, TMEM16A is essential for both the cGMP-dependent and the classical ICl(Ca). Furthermore, TMEM16A has a role in arterial contraction while bestrophins do not. TMEM16A’s role in the contractile response cannot be explained however only by a simple suppression of the depolarization by Cl– channels. It is suggested that TMEM16A expression modulates voltage-gated Ca2+ influx in a voltage-independent manner and recent studies also demonstrate a complex role of TMEM16A in modulating other membrane proteins.
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21
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Mijušković A, Kokić AN, Dušić ZO, Slavić M, Spasić MB, Blagojević D. Chloride channels mediate sodium sulphide-induced relaxation in rat uteri. Br J Pharmacol 2015; 172:3671-86. [PMID: 25857480 DOI: 10.1111/bph.13161] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 03/23/2015] [Accepted: 03/30/2015] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Hydrogen sulphide reduces uterine contractility and is of potential interest as a treatment for uterine disorders. The aim of this study was to explore the mechanism of sodium sulphide (Na2 S)-induced relaxation of rat uterus, investigate the importance of redox effects and ion channel-mediated mechanisms, and any interactions between these two mechanisms. EXPERIMENTAL APPROACH Organ bath studies were employed to assess the pharmacological effects of Na2 S in uterine strips by exposing them to Na2 S with or without Cl(-) channel blockers (DIDS, NFA, IAA-94, T16Ainh-A01, TA), raised KCl (15 and 75 mM), K(+) channel inhibitors (glibenclamide, TEA, 4-AP), L-type Ca(2+) channel activator (S-Bay K 8644), propranolol and methylene blue. The activities of antioxidant enzymes were measured in homogenates of treated uteri. The expression of bestrophin channel 1 (BEST-1) was determined by Western blotting and RT-PCR. KEY RESULTS Na2 S caused concentration-dependent reversible relaxation of spontaneously active and calcium-treated uteri, affecting both amplitude and frequency of contractions. Uteri exposed to 75 mM KCl were less sensitive to Na2 S compared with uteri in 15 mM KCl. Na2 S-induced relaxations were abolished by DIDS, but unaffected by other modulators or by the absence of extracellular HCO3 (-) , suggesting the involvement of chloride ion channels. Na2 S in combination with different modulators provoked specific changes in the anti-oxidant profiles of uteri. The expression of BEST-1, both mRNA and protein, was demonstrated in rat uteri. CONCLUSIONS AND IMPLICATIONS The relaxant effects of Na2 S in rat uteri are mediated mainly via a DIDS-sensitive Cl(-) -pathway. Components of the relaxation are redox- and Ca(2+) -dependent.
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Affiliation(s)
- Ana Mijušković
- Department of Physiology, Institute for Biological Research 'Siniša Stanković', University of Belgrade, Belgrade, Serbia
| | - Aleksandra Nikolić Kokić
- Department of Physiology, Institute for Biological Research 'Siniša Stanković', University of Belgrade, Belgrade, Serbia
| | - Zorana Oreščanin Dušić
- Department of Physiology, Institute for Biological Research 'Siniša Stanković', University of Belgrade, Belgrade, Serbia
| | - Marija Slavić
- Department of Physiology, Institute for Biological Research 'Siniša Stanković', University of Belgrade, Belgrade, Serbia
| | - Mihajlo B Spasić
- Department of Physiology, Institute for Biological Research 'Siniša Stanković', University of Belgrade, Belgrade, Serbia
| | - Duško Blagojević
- Department of Physiology, Institute for Biological Research 'Siniša Stanković', University of Belgrade, Belgrade, Serbia
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Marmorstein AD, Kinnick TR, Stanton JB, Johnson AA, Lynch RM, Marmorstein LY. Bestrophin-1 influences transepithelial electrical properties and Ca2+ signaling in human retinal pigment epithelium. Mol Vis 2015; 21:347-59. [PMID: 25878489 PMCID: PMC4390793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/30/2015] [Indexed: 11/16/2022] Open
Abstract
PURPOSE Mutations in BEST1, encoding Bestrophin-1 (Best1), cause Best vitelliform macular dystrophy (BVMD) and other inherited retinal degenerative diseases. Best1 is an integral membrane protein localized to the basolateral plasma membrane of the retinal pigment epithelium (RPE). Data from numerous in vitro and in vivo models have demonstrated that Best1 regulates intracellular Ca2+ levels. Although it is known from in vitro and crystal structure data that Best1 is also a calcium-activated anion channel, evidence for Best1 functioning as a channel in human RPE is lacking. To assess Best1-associated channel activity in the RPE, we examined the transepithelial electrical properties of fetal human RPE (fhRPE) cells, which express endogenous Best1. METHODS Using adenovirus-mediated gene transfer, we overexpressed Best1 and the BVMD mutant Best1W93C in fhRPE cells and assessed resting transepithelial potential (TEP), transepithelial resistance, short circuit current (Isc), and intracellular Ca2+ levels. Cl- currents were directly measured in transfected HEK293 cells using whole-cell patch clamp. RESULTS Best1W93C showed ablated Cl- currents and, when co-expressed, suppressed the channel activity of Best1 in HEK293 cells. In fhRPE, overexpression of Best1 increased TEP and Isc, while Best1W93C diminished TEP and Isc. Substitution of Cl- in the bath media resulted in a significant reduction of Isc in monolayers overexpressing Best1, but no significant Isc change in monolayers expressing Best1W93C. We removed Ca2+ as a limit on transepithelial electrical properties by treating cells with ionomycin, and found that changes in Isc and TEP for monolayers expressing Best1 were absent in monolayers expressing Best1W93C. Similarly, inhibition of calcium-activated anion channels with niflumic acid reduced both Isc and TEP of control and Best1 monolayers, but did not notably affect Best1W93C monolayers. Stimulation with extracellular ATP induced an increase in TEP in control monolayers that was greater than that observed in those expressing Best1(W93C). Examination of [Ca2+]i following ATP stimulation demonstrated that the expression of Best1W93C impaired intracellular Ca2+ signaling. CONCLUSIONS These data indicate that Best1 activity strongly influences electrophysiology and Ca2+ signaling in RPE cells, and that a common BVMD mutation disrupts both of these parameters. Our findings support the hypothesis that Best1 functions as an anion channel in human RPE.
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23
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Reichhart N, Keckeis S, Fried F, Fels G, Strauss O. Regulation of surface expression of TRPV2 channels in the retinal pigment epithelium. Graefes Arch Clin Exp Ophthalmol 2015; 253:865-74. [DOI: 10.1007/s00417-014-2917-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 12/23/2014] [Accepted: 12/23/2014] [Indexed: 12/31/2022] Open
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Effects of alternative splicing on the function of bestrophin-1 calcium-activated chloride channels. Biochem J 2014; 458:575-83. [PMID: 24341532 DOI: 10.1042/bj20121546] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The proposed Ca2+-activated Cl- channel protein Best1 (bestrophin 1) is expressed and functionally important in the retina and in the brain. Human BEST1 has two known splice variants, Best1V1 and Best1V2, which arise from alternative splicing of two exons: exon 2 splicing results in a unique N-terminal domain, whereas alternative splicing of exon 11 produces two mutually exclusive C-termini. Prior studies were limited to Best1V1 and its clinically relevant mutations. In the present work, we cloned a novel splice variant of Best1V1 missing exon 2 (Best1V1Δex2) and differing from each of the two previously identified isoforms by one alternatively spliced domain. This finding allowed us to determine the role for alternative splicing of the Best1 N- and C-termini. We heteroexpressed Best1V1Δex2 in HEK (human embryonic kidney)-293 cells, and compared its properties with Best1V1 and Best1V2. Western blot analysis confirmed protein expression from all three splice variants. Both Best1V1 and Best1V1Δex2 successfully formed Ca2+-activated Cl- channels, demonstrating that the N-terminus encoded by exon 2 is not essential for channel function. In contrast, Best1V2-expressing cells had no detectable Ca2+-activated Cl- currents, pointing to a critical role for splicing of the C-terminus. Surface protein biotinylation demonstrated that Best1V1 and Best1V1Δex2 are trafficked to the plasma membrane, whereas Best1V2 is not. These results define the impact of alternative splicing on Best1 function, and should be taken into consideration in future modelling of the Best1 protein structure.
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25
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Johnson AA, Lee YS, Chadburn AJ, Tammaro P, Manson FD, Marmorstein LY, Marmorstein AD. Disease-causing mutations associated with four bestrophinopathies exhibit disparate effects on the localization, but not the oligomerization, of Bestrophin-1. Exp Eye Res 2014; 121:74-85. [PMID: 24560797 PMCID: PMC4123461 DOI: 10.1016/j.exer.2014.02.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 01/31/2014] [Accepted: 02/07/2014] [Indexed: 01/11/2023]
Abstract
BEST1 encodes Bestrophin-1 (Best1), a homo-oligomeric, integral membrane protein localized to the basolateral plasma membrane of the retinal pigment epithelium. Mutations in BEST1 cause five distinct retinal degenerative diseases, including adult vitelliform macular dystrophy (AVMD), autosomal recessive bestrophinopathy (ARB), autosomal dominant vitreoretinochoroidopathy (ADVIRC), and retinitis pigmentosa (RP). The mechanisms underlying these diseases and why mutations cause one disease over another are, for the most part, unknown. To gain insights into these four diseases, we expressed 28 Best1 mutants fused to YFP in polarized MDCK monolayers and, via confocal microscopy and immunofluorescence, live-cell FRET, and reciprocal co-immunoprecipitation experiments, screened these mutants for defects in localization and oligomerization. All 28 mutants exhibited comparable FRET efficiencies to and co-immunoprecipitated with WT Best1, indicating unimpaired oligomerization. RP- and ADVIRC-associated mutants were properly localized to the basolateral plasma membrane of cells, while two AVMD and most ARB mutants were mislocalized. When co-expressed, all mislocalized mutants caused mislocalization of WT Best1 to intracellular compartments. Our current and past results indicate that mislocalization of Best1 is not an absolute feature of any individual bestrophinopathy, occurring in AVMD, BVMD, and ARB. Furthermore, some ARB mutants that do not also cause dominant disease cause mislocalization of Best1, indicating that mislocalization is not a cause of disease, and that absence of Best1 activity from the plasma membrane is tolerated. Lastly, we find that the ARB truncation mutants L174Qfs*57 and R200X can form oligomers with WT Best1, indicating that the first ∼174 amino acids of Best1 are sufficient for oligomerization to occur.
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Affiliation(s)
- Adiv A Johnson
- Physiological Sciences Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ 85724, USA; Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905, USA.
| | - Yong-Suk Lee
- Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905, USA.
| | - Andrew J Chadburn
- Faculty of Life Sciences, Faculty of Medical and Human Sciences, The University of Manchester, Manchester M13 9PT, United Kingdom.
| | - Paolo Tammaro
- Faculty of Life Sciences, Faculty of Medical and Human Sciences, The University of Manchester, Manchester M13 9PT, United Kingdom.
| | - Forbes D Manson
- Manchester Centre for Genomic Medicine, Faculty of Medical and Human Sciences, The University of Manchester, Manchester M13 9PT, United Kingdom.
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Strauß O, Müller C, Reichhart N, Tamm ER, Gomez NM. The Role of Bestrophin-1 in Intracellular Ca2+ Signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:113-9. [DOI: 10.1007/978-1-4614-3209-8_15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Pasquay C, Wang LF, Lorenz B, Preising MN. Bestrophin 1 – Phenotypes and Functional Aspects in Bestrophinopathies. Ophthalmic Genet 2013; 36:193-212. [DOI: 10.3109/13816810.2013.863945] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Guziewicz KE, Zangerl B, Komáromy AM, Iwabe S, Chiodo VA, Boye SL, Hauswirth WW, Beltran WA, Aguirre GD. Recombinant AAV-mediated BEST1 transfer to the retinal pigment epithelium: analysis of serotype-dependent retinal effects. PLoS One 2013; 8:e75666. [PMID: 24143172 PMCID: PMC3797066 DOI: 10.1371/journal.pone.0075666] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 08/17/2013] [Indexed: 02/06/2023] Open
Abstract
Mutations in the BEST1 gene constitute an underlying cause of juvenile macular dystrophies, a group of retinal disorders commonly referred to as bestrophinopathies and usually diagnosed in early childhood or adolescence. The disease primarily affects macular and paramacular regions of the eye leading to major declines in central vision later in life. Currently, there is no cure or surgical management for BEST1-associated disorders. The recently characterized human disease counterpart, canine multifocal retinopathy (cmr), recapitulates a full spectrum of clinical and molecular features observed in human bestrophinopathies and offers a valuable model system for development and testing of therapeutic strategies. In this study, the specificity, efficiency and safety of rAAV-mediated transgene expression driven by the human VMD2 promoter were assessed in wild-type canine retinae. While the subretinal delivery of rAAV2/1 vector serotype was associated with cone damage in the retina when BEST1 and GFP were co-expressed, the rAAV2/2 vector serotype carrying either GFP reporter or BEST1 transgene under control of human VMD2 promoter was safe, and enabled specific transduction of the RPE cell monolayer that was stable for up to 6 months post injection. These encouraging studies with the rAAV2/2 vector lay the groundwork for development of gene augmentation therapy for human bestrophinopathies.
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Affiliation(s)
- Karina E. Guziewicz
- Section of Ophthalmology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (KEG); (GDA)
| | - Barbara Zangerl
- Section of Ophthalmology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Centre for Eye Health, University of New South Wales, Kensington, Australia
- * E-mail: (KEG); (GDA)
| | - András M. Komáromy
- Section of Ophthalmology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Simone Iwabe
- Section of Ophthalmology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Vincent A. Chiodo
- Department of Ophthalmology, University of Florida, Gainesville, Florida, United States of America
| | - Sanford L. Boye
- Department of Ophthalmology, University of Florida, Gainesville, Florida, United States of America
| | - William W. Hauswirth
- Department of Ophthalmology, University of Florida, Gainesville, Florida, United States of America
| | - William A. Beltran
- Section of Ophthalmology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Gustavo D. Aguirre
- Section of Ophthalmology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Doumanov JA, Zeitz C, Gimenez PD, Audo I, Krishna A, Alfano G, Diaz MLB, Moskova-Doumanova V, Lancelot ME, Sahel JA, Nandrot EF, Bhattacharya SS. Disease-causing mutations in BEST1 gene are associated with altered sorting of bestrophin-1 protein. Int J Mol Sci 2013; 14:15121-40. [PMID: 23880862 PMCID: PMC3742291 DOI: 10.3390/ijms140715121] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/02/2013] [Accepted: 07/04/2013] [Indexed: 01/03/2023] Open
Abstract
Mutations in BEST1 gene, encoding the bestrophin-1 (Best1) protein are associated with macular dystrophies. Best1 is predominantly expressed in the retinal pigment epithelium (RPE), and is inserted in its basolateral membrane. We investigated the cellular localization in polarized MDCKII cells of disease-associated Best1 mutant proteins to study specific sorting motifs of Best1. Real-time PCR and western blots for endogenous expression of BEST1 in MDCK cells were performed. Best1 mutant constructs were generated using site-directed mutagenesis and transfected in MDCK cells. For protein sorting, confocal microscopy studies, biotinylation assays and statistical methods for quantification of mislocalization were used. Analysis of endogenous expression of BEST1 in MDCK cells revealed the presence of BEST1 transcript but no protein. Confocal microscopy and quantitative analyses indicate that transfected normal human Best1 displays a basolateral localization in MDCK cells, while cell sorting of several Best1 mutants (Y85H, Q96R, L100R, Y227N, Y227E) was altered. In contrast to constitutively active Y227E, constitutively inactive Y227F Best1 mutant localized basolaterally similar to the normal Best1 protein. Our data suggest that at least three basolateral sorting motifs might be implicated in proper Best1 basolateral localization. In addition, non-phosphorylated tyrosine 227 could play a role for basolateral delivery.
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Affiliation(s)
- Jordan A. Doumanov
- Biological Faculty, Sofia University “Saint Kliment Ohridski”, 8 Dragan Tzankov str, Sofia 1164, Bulgaria; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +359-2-8167-204; Fax: +359-2-8656-641
| | - Christina Zeitz
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR_S 968, Paris F-75012, France; E-Mails: (C.Z.); (I.A.); (M.-E.L.); (J.-A.S.); (E.F.N.); (S.S.B.)
- Centre National de la Recherche Scientifique (CNRS), UMR_7210, Paris F-75012, France
- Centre de Recherche Institut de la Vision, Université Pierre et Marie Curie-Paris 6, 17 rue Moreau, Paris F-75012, France
| | - Paloma Dominguez Gimenez
- Andalusian Center of Molecular Biology and Regenerative Medicine, Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Avda. Americo Vespucio s/n, Parque Cientifico y Tecnologico, Isla de la Cartuja 41092, Sevilla, Spain; E-Mails: (P.D.G.); (A.K.); (M.L.B.D.)
| | - Isabelle Audo
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR_S 968, Paris F-75012, France; E-Mails: (C.Z.); (I.A.); (M.-E.L.); (J.-A.S.); (E.F.N.); (S.S.B.)
- Centre National de la Recherche Scientifique (CNRS), UMR_7210, Paris F-75012, France
- Centre de Recherche Institut de la Vision, Université Pierre et Marie Curie-Paris 6, 17 rue Moreau, Paris F-75012, France
- Centre de Référence Maladies Rares/Centre d’Investigation Clinique (CMR/CIC), 503 INSERM, CHNO des Quinze-Vingts, Paris F-75012, France
| | - Abhay Krishna
- Andalusian Center of Molecular Biology and Regenerative Medicine, Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Avda. Americo Vespucio s/n, Parque Cientifico y Tecnologico, Isla de la Cartuja 41092, Sevilla, Spain; E-Mails: (P.D.G.); (A.K.); (M.L.B.D.)
| | - Giovanna Alfano
- Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Maria Luz Bellido Diaz
- Andalusian Center of Molecular Biology and Regenerative Medicine, Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Avda. Americo Vespucio s/n, Parque Cientifico y Tecnologico, Isla de la Cartuja 41092, Sevilla, Spain; E-Mails: (P.D.G.); (A.K.); (M.L.B.D.)
| | - Veselina Moskova-Doumanova
- Biological Faculty, Sofia University “Saint Kliment Ohridski”, 8 Dragan Tzankov str, Sofia 1164, Bulgaria; E-Mail:
| | - Marie-Elise Lancelot
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR_S 968, Paris F-75012, France; E-Mails: (C.Z.); (I.A.); (M.-E.L.); (J.-A.S.); (E.F.N.); (S.S.B.)
- Centre National de la Recherche Scientifique (CNRS), UMR_7210, Paris F-75012, France
- Centre de Recherche Institut de la Vision, Université Pierre et Marie Curie-Paris 6, 17 rue Moreau, Paris F-75012, France
| | - José-Alain Sahel
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR_S 968, Paris F-75012, France; E-Mails: (C.Z.); (I.A.); (M.-E.L.); (J.-A.S.); (E.F.N.); (S.S.B.)
- Centre National de la Recherche Scientifique (CNRS), UMR_7210, Paris F-75012, France
- Centre de Recherche Institut de la Vision, Université Pierre et Marie Curie-Paris 6, 17 rue Moreau, Paris F-75012, France
- Centre de Référence Maladies Rares/Centre d’Investigation Clinique (CMR/CIC), 503 INSERM, CHNO des Quinze-Vingts, Paris F-75012, France
- Fondation Ophtalmologique Adolphe de Rothschild, Paris F-75019, France
| | - Emeline F. Nandrot
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR_S 968, Paris F-75012, France; E-Mails: (C.Z.); (I.A.); (M.-E.L.); (J.-A.S.); (E.F.N.); (S.S.B.)
- Centre National de la Recherche Scientifique (CNRS), UMR_7210, Paris F-75012, France
- Centre de Recherche Institut de la Vision, Université Pierre et Marie Curie-Paris 6, 17 rue Moreau, Paris F-75012, France
| | - Shomi S. Bhattacharya
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR_S 968, Paris F-75012, France; E-Mails: (C.Z.); (I.A.); (M.-E.L.); (J.-A.S.); (E.F.N.); (S.S.B.)
- Centre National de la Recherche Scientifique (CNRS), UMR_7210, Paris F-75012, France
- Centre de Recherche Institut de la Vision, Université Pierre et Marie Curie-Paris 6, 17 rue Moreau, Paris F-75012, France
- Andalusian Center of Molecular Biology and Regenerative Medicine, Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Avda. Americo Vespucio s/n, Parque Cientifico y Tecnologico, Isla de la Cartuja 41092, Sevilla, Spain; E-Mails: (P.D.G.); (A.K.); (M.L.B.D.)
- Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
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Johnson AA, Lee YS, Stanton JB, Yu K, Hartzell CH, Marmorstein LY, Marmorstein AD. Differential effects of Best disease causing missense mutations on bestrophin-1 trafficking. Hum Mol Genet 2013; 22:4688-97. [PMID: 23825107 DOI: 10.1093/hmg/ddt316] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in bestrophin-1 (Best1) cause Best vitelliform macular dystrophy (BVMD), a dominantly inherited retinal degenerative disease. Best1 is a homo-oligomeric anion channel localized to the basolateral surface of retinal pigment epithelial (RPE) cells. A number of Best1 mutants mislocalize in Madin-Darby canine kidney (MDCK) cells. However, many proteins traffic differently in MDCK and RPE cells, and MDCK cells do not express endogenous Best1. Thus, effects of Best1 mutations on localization in MDCK cells may not translate to RPE cells. To determine whether BVMD causing mutations affect Best1 localization, we compared localization and oligomerization of Best1 with Best1 mutants V9M, W93C, and R218C. In MDCK cells, Best1 and Best1(R218C) were basolaterally localized. Best1(W93C) and Best1(V9M) accumulated in cells. In cultured fetal human retinal pigment epithelium cells (fhRPE) expressing endogenous Best1, Best1(R218C) and Best1(W93C) were basolateral. Best1(V9M) was intracellular. All three mutants exhibited similar fluorescence resonance energy transfer (FRET) efficiencies to, and co-immunoprecipitated with Best1, indicating unimpaired oligomerization. When human Best1 was expressed in RPE in mouse eyes it was basolaterally localized. However, Best1(V9M) accumulated in intracellular compartments in mouse RPE. Co-expression of Best1 and Best1(W93C) in MDCK cells resulted in basolateral localization of both Best1 and Best1(W93C), but co-expression of Best1 with Best1(V9M) resulted in mislocalization of both proteins. We conclude that different mutations in Best1 cause differential effects on its localization and that this effect varies with the presence or absence of wild-type (WT) Best1. Furthermore, MDCK cells can substitute for RPE when examining the effects of BVMD causing mutations on Best1 localization if co-expressed with WT Best1.
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Mitochondria dependent pathway is involved in the protective effect of bestrophin-3 on hydrogen peroxide-induced apoptosis in basilar artery smooth muscle cells. Apoptosis 2013; 18:556-65. [DOI: 10.1007/s10495-013-0828-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Gómez NM, Tamm ER, Strauβ O. Role of bestrophin-1 in store-operated calcium entry in retinal pigment epithelium. Pflugers Arch 2012. [PMID: 23207577 DOI: 10.1007/s00424-012-1181-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The retinal pigment epithelium (RPE) expresses bestrophin-1 where mutant bestrophin cause retinal degenerations. Overexpression of bestrophin-1 demonstrated Ca(2+)-dependent Cl(-) channel function, whereas the RPE in bestrophin-1 knockout or mutant bestrophin-1 knock-in mice showed no change in Cl(-) conductance. To account for these apparently mutually exclusive findings, we investigated the function of endogenously expressed bestrophin-1 in a short-time RPE cell culture system by means of immunocytochemistry, Ca(2+) imaging, and siRNA knockdown. Immunocytochemical quantification of bestrophin-1 localization demonstrated 2.5 times higher co-localization with the endoplasmic reticulum (ER) Ca(2+)-sensor protein, Stim-1, than with the membrane protein β-catenin, implicating it in store-operated Ca(2+) entry (SOCE). Ca(2+) release from ER stores under extracellular Ca(2+)-free conditions using thapsigargin (1 μM) to inhibit endoplasmic Ca(2+) ATPase (SERCA) followed by re-adjustment of extracellular Ca(2+) to physiological levels activated SOCE, which was insensitive to the blocker of numerous transient receptor potential channels and voltage-dependent Ca(2+) channels SKF96563 (1 μM). SOCE was augmented at 5 μM and inhibited at 75 μM by 2-aminoethoxydiphenyl borate which indicates the involvement Orai-1 channels. In confirmation, SOCE was decreased by siRNA knockdown of Orai-1 expression. SOCE amplitude was strongly reduced by siRNA knockdown of bestrophin-1 expression, which was due to neither changes in Stim-1/Orai-1 expression nor Stim-1/bestrophin-1 interaction. The amount of Ca(2+) released by SERCA inhibition was reduced after siRNA knockdown of bestrophin-1, but not of Orai-1. In conclusion we found that a proportion of bestrophin-1 is functionally localized to ER Ca(2+) stores where it influences the amount of Ca(2+) and therefore Ca(2+) signals which result from activation of Orai-1 via Stim-1.
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Affiliation(s)
- Néstor Más Gómez
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Franz-Josef-Strauss-Allee 11, 93053, Regensburg, Germany
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Barro-Soria R, Stindl J, Müller C, Foeckler R, Todorov V, Castrop H, Strauß O. Angiotensin-2-mediated Ca2+ signaling in the retinal pigment epithelium: role of angiotensin-receptor-associated-protein and TRPV2 channel. PLoS One 2012. [PMID: 23185387 PMCID: PMC3502274 DOI: 10.1371/journal.pone.0049624] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Angiotensin II (AngII) receptor (ATR) is involved in pathologic local events such as neovascularisation and inflammation including in the brain and retina. The retinal pigment epithelium (RPE) expresses ATR in its AT1R form, angiotensin-receptor-associated protein (Atrap), and transient-receptor-potential channel-V2 (TRPV2). AT1R and Atrap co-localize to the basolateral membrane of the RPE, as shown by immunostaining. Stimulation of porcine RPE (pRPE) cells by AngII results in biphasic increases in intracellular free Ca(2+)inhibited by losartan. Xestospongin C (xest C) and U-73122, blockers of IP3R and PLC respectively, reduced AngII-evoked Ca(2+)response. RPE cells from Atrap(-/-) mice showed smaller AngII-evoked Ca(2+)peak (by 22%) and loss of sustained Ca(2+)elevation compared to wild-type. The TRPV channel activator cannabidiol (CBD) at 15 µM stimulates intracellular Ca(2+)-rise suggesting that porcine RPE cells express TRPV2 channels. Further evidence supporting the functional expression of TRPV2 channels comes from experiments in which 100 µM SKF96365 (a TRPV channel inhibitor) reduced the cannabidiol-induced Ca(2+)-rise. Application of SKF96365 or reduction of TRPV2 expression by siRNA reduced the sustained phase of AngII-mediated Ca(2+)transients by 53%. Thus systemic AngII, an effector of the local renin-angiotensin system stimulates biphasic Ca(2+)transients in the RPE by releasing Ca(2+)from cytosolic IP3-dependent stores and activating ATR/Atrap and TRPV2 channels to generate a sustained Ca(2+)elevation.
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Affiliation(s)
- Rene Barro-Soria
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Julia Stindl
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Claudia Müller
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Renate Foeckler
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Vladimir Todorov
- Institute of Physiology, University of Regensburg, Regensburg, Germany
- Laboratory for Experimental Nephrology, Dresden University of Technology, Dresden, Germany
| | - Hayo Castrop
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Olaf Strauß
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
- * E-mail:
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