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Wasilewska I, Majewski Ł, Adamek-Urbańska D, Mondal SS, Baranykova S, Gupta RK, Bielecki D, Winata CL, Kuznicki J. Lack of Stim2 Affects Vision-Dependent Behavior and Sensitivity to Hypoxia. Zebrafish 2023; 20:146-159. [PMID: 37590563 DOI: 10.1089/zeb.2022.0068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023] Open
Abstract
Stromal interaction molecules (STIMs) are endoplasmic reticulum-resident proteins that regulate Ca2+ homeostasis and signaling by store-operated calcium entry (SOCE). The different properties and functions of STIM1 and STIM2 have been described mostly based on work in vitro. STIM2 knockout mice do not survive until adulthood. Therefore, we generated and characterized stim2a and stim2b double-knockout zebrafish. The (stim2a;stim2b)-/- zebrafish did not have any apparent morphological phenotype. However, RNA sequencing revealed 1424 differentially expressed genes. One of the most upregulated genes was annexin A3a, which is a marker of activated microglia. This corresponded well to an increase in Neutral Red staining in the in vivo imaging of the (stim2a;stim2b)-/- zebrafish brain. The lack of Stim2 decreased zebrafish survival under low oxygen conditions. Behavioral tests, such as the visual-motor response test and dark-light preference test, indicated that (stim2a;stim2b)-/- larvae might have problems with vision. This was consistent with the downregulation of many genes that are related to light perception. The periodic acid-Schiff staining of retina sections from adult zebrafish revealed alterations of the stratum pigmentosum, suggesting the involvement of a Stim2-dependent process in visual perception. Altogether, these data reveal new functions for Stim2 in the nervous system.
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Affiliation(s)
- Iga Wasilewska
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Warsaw, Poland
| | - Łukasz Majewski
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Dobrochna Adamek-Urbańska
- Department of Ichthyology and Biotechnology in Aquaculture, Institute of Animal Sciences, Warsaw University of Life Sciences, Warsaw, Poland
| | - Shamba S Mondal
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Sofiia Baranykova
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Rishikesh K Gupta
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Dominik Bielecki
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Cecilia L Winata
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Jacek Kuznicki
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
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Han IC, Coussa RG, Mansoor M, Critser DB, Sohn EH, Russell JF, Stone EM. Choroidal Neovascularization Is Common in Best Vitelliform Macular Dystrophy and Plays a Role in Vitelliform Lesion Evolution. Ophthalmol Retina 2023; 7:441-449. [PMID: 36528270 PMCID: PMC10164042 DOI: 10.1016/j.oret.2022.11.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/29/2022] [Accepted: 11/30/2022] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Choroidal neovascularization (CNV) is usually considered to be a late-stage complication in Best vitelliform macular dystrophy (BVMD) and can be difficult to diagnose with fluorescein angiography. This study used swept-source (SS) OCT angiography (OCTA) to evaluate the prevalence of CNV in BVMD, identify structural features associated with CNV, and provide insight into the role of CNV in vitelliform lesion evolution. DESIGN Institutional review board-approved, retrospective, cross-sectional, and longitudinal study. PARTICIPANTS Patients with molecularly confirmed BVMD. METHODS Charts from consecutive patients with BVMD imaged with SS-OCTA (PLEX Elite 9000, Carl-Zeiss Meditec Inc) at the University of Iowa from September 2017 to October 2021 were reviewed. Clinical data, including age, gender, best-corrected visual acuity (BCVA), and treatment with intravitreal anti-VEGF injections were recorded. The presence of CNV on SS-OCTA was determined by expert graders and correlated with structural features, such as interstitial fluid, subretinal fluid, nodular subretinal pillar, focal choroidal excavation (FCE), and subfoveal choroidal thickness, with a P value of < 0.05 considered statistically significant. MAIN OUTCOME MEASURES Presence of CNV on SS-OCTA and correlation with structural features on SS-OCT. RESULTS A total of 53 eyes from 27 patients (13 women; 48.1%) were included. The mean age was 45 years (range, 8-79 years), and the mean logarithm of the minimum angle of resolution BCVA was 0.38 (range, 0-1). Choroidal neovascularization was identified on SS-OCTA in 27 eyes (50.9%), of which 63.0% had a vitelliform (Gass stage 2) lesion. In 40.7% (11 of 27) of eyes, there was no prior clinical diagnosis of CNV. Other structural features associated with CNV included FCEs (15.1%, 8 of 53 eyes) and nodular pillars (15.1%, 8 of 53 eyes) (P < 0.01). Seven patients had available longitudinal imaging, and most of these patients had CNV visible on SS-OCTA (71.4%; 10 of 14 eyes). CONCLUSION Choroidal neovascularization is common in BVMD, including in the early stages of the disease. The presence of FCEs or nodular pillars should heighten the clinical suspicion of CNV, which may accelerate vitelliform lesion evolution. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.
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Affiliation(s)
- Ian C Han
- Iowa Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa.
| | - Razek Georges Coussa
- Iowa Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa; Dean McGee Eye Institute, Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Mahsaw Mansoor
- Iowa Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - D Brice Critser
- Iowa Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Elliott H Sohn
- Iowa Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Jonathan F Russell
- Iowa Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Edwin M Stone
- Iowa Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa
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Cellular and Molecular Mechanisms of Pathogenesis Underlying Inherited Retinal Dystrophies. Biomolecules 2023; 13:biom13020271. [PMID: 36830640 PMCID: PMC9953031 DOI: 10.3390/biom13020271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/23/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
Inherited retinal dystrophies (IRDs) are congenital retinal degenerative diseases that have various inheritance patterns, including dominant, recessive, X-linked, and mitochondrial. These diseases are most often the result of defects in rod and/or cone photoreceptor and retinal pigment epithelium function, development, or both. The genes associated with these diseases, when mutated, produce altered protein products that have downstream effects in pathways critical to vision, including phototransduction, the visual cycle, photoreceptor development, cellular respiration, and retinal homeostasis. The aim of this manuscript is to provide a comprehensive review of the underlying molecular mechanisms of pathogenesis of IRDs by delving into many of the genes associated with IRD development, their protein products, and the pathways interrupted by genetic mutation.
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Constable PA, Kapoor G. Is white the right light for the clinical electrooculogram? Doc Ophthalmol 2021; 143:297-304. [PMID: 34160736 DOI: 10.1007/s10633-021-09845-9] [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: 04/13/2021] [Accepted: 06/14/2021] [Indexed: 11/30/2022]
Abstract
PURPOSE To investigate if a lower luminance monochromatic LED stimulus could be used as an alternative to a high luminance white light for the clinical electrooculogram. METHODS Clinical electrooculograms were recorded in color normal participants (N = 23) aged 22.6 ± 1.2 years, 7 male and 16 female using the standard 100 cd.m-2 white illuminant and four monochromatic LEDs with peak wavelengths of 448, 534, 596 and 634 nm at 30 cd.m-2. Pupils were dilated and there was a 30 cd.m-2pre-adaptation to white light for 2 min followed by 15 min dark adaptation and 20 min recording in the light stimulus using a Ganzfeld stimulator. RESULTS The normalized LP:DTratio for the short wavelength LED (448 nm) was equivalent in amplitude and timing to the ISCEV standard EOG (p = .99). The LP:DTratio for the white (100 cd.m-2) and 448 nm (30 cd.m-2) were (median ± SEM): 2.49 ± .11 and 2.47 ± .11. The time to light-rise peak was also equivalent being 9.0 ± .2 and 8.0 ± .4 min (p = .54). CONCLUSIONS Consideration may be given to using a short wavelength monochromatic stimulus that is more comfortable for the subject than the current 100 cd.m-2 illuminant.
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Affiliation(s)
- Paul A Constable
- Caring Futures Institute, College of Nursing and Health Sciences, Flinders University, PO Box 2100, Adelaide, SA, 5001, Australia.
| | - Garima Kapoor
- College of Medicine and Public Health, Flinders University, Adelaide, Australia
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Kolesnikov D, Perevoznikova A, Gusev K, Glushankova L, Kaznacheyeva E, Shalygin A. Electrophysiological Properties of Endogenous Single Ca 2+ Activated Cl - Channels Induced by Local Ca 2+ Entry in HEK293. Int J Mol Sci 2021; 22:4767. [PMID: 33946319 PMCID: PMC8124839 DOI: 10.3390/ijms22094767] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/26/2021] [Accepted: 04/28/2021] [Indexed: 12/19/2022] Open
Abstract
Microdomains formed by proteins of endoplasmic reticulum and plasma membrane play a key role in store-operated Ca2+ entry (SOCE). Ca2+ release through inositol 1,4,5-trisphosphate receptor (IP3R) and subsequent Ca2+ store depletion activate STIM (stromal interaction molecules) proteins, sensors of intraluminal Ca2+, which, in turn, open the Orai channels in plasma membrane. Downstream to this process could be activated TRPC (transient receptor potential-canonical) calcium permeable channels. Using single channel patch-clamp technique we found that a local Ca2+ entry through TRPC1 channels activated endogenous Ca2+-activated chloride channels (CaCCs) with properties similar to Anoctamin6 (TMEM16F). Our data suggest that their outward rectification is based on the dependence from membrane potential of both the channel conductance and the channel activity: (1) The conductance of active CaCCs highly depends on the transmembrane potential (from 3 pS at negative potentials till 60 pS at positive potentials); (2) their activity (NPo) is enhanced with increasing Ca2+ concentration and/or transmembrane potential, conversely lowering of intracellular Ca2+ concentration reduced the open state dwell time; (3) CaCC amplitude is only slightly increased by intracellular Ca2+ concentration. Experiments with Ca2+ buffering by EGTA or BAPTA suggest close local arrangement of functional CaCCs and TRPC1 channels. It is supposed that Ca2+-activated chloride channels are involved in Ca2+ entry microdomains.
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Affiliation(s)
| | | | | | | | - Elena Kaznacheyeva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, 194064 St. Petersburg, Russia; (D.K.); (A.P.); (K.G.); (L.G.)
| | - Alexey Shalygin
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, 194064 St. Petersburg, Russia; (D.K.); (A.P.); (K.G.); (L.G.)
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Singh Grewal S, Smith JJ, Carr AJF. Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies. Ther Adv Ophthalmol 2021; 13:2515841421997191. [PMID: 33738427 PMCID: PMC7934022 DOI: 10.1177/2515841421997191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 01/27/2021] [Indexed: 12/17/2022] Open
Abstract
Bestrophinopathies are a group of clinically distinct inherited retinal dystrophies that typically affect the macular region, an area synonymous with central high acuity vision. This spectrum of disorders is caused by mutations in bestrophin1 (BEST1), a protein thought to act as a Ca2+-activated Cl- channel in the retinal pigment epithelium (RPE) of the eye. Although bestrophinopathies are rare, over 250 individual pathological mutations have been identified in the BEST1 gene, with many reported to have various clinical expressivity and incomplete penetrance. With no current clinical treatments available for patients with bestrophinopathies, understanding the role of BEST1 in cells and the pathological pathways underlying disease has become a priority. Induced pluripotent stem cell (iPSC) technology is helping to uncover disease mechanisms and develop treatments for RPE diseases, like bestrophinopathies. Here, we provide a comprehensive review of the pathophysiology of bestrophinopathies and highlight how patient-derived iPSC-RPE are being used to test new genomic therapies in vitro.
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Affiliation(s)
| | - Joseph J Smith
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Amanda-Jayne F Carr
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
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Yoshimoto S, Matsuda M, Kato K, Jimi E, Takeuchi H, Nakano S, Kajioka S, Matsuzaki E, Hirofuji T, Inoue R, Hirata M, Morita H. Volume-regulated chloride channel regulates cell proliferation and is involved in the possible interaction between TMEM16A and LRRC8A in human metastatic oral squamous cell carcinoma cells. Eur J Pharmacol 2021; 895:173881. [PMID: 33476655 DOI: 10.1016/j.ejphar.2021.173881] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 12/29/2020] [Accepted: 01/12/2021] [Indexed: 10/22/2022]
Abstract
OBJECTIVES Volume-regulated anion channels (VRACs), expressed in various cells, play an important role in cell volume regulation. Despite being physiologically defined almost half a century ago, only the molecular candidates of VRAC, TMEM16A, LRRC8A, and bestrophin-1 (BEST1), are known. Here, we aimed to explore the functional significance of VRAC in, HST-1, an oral squamous cell carcinoma (OSCC) cell line. METHODS Cell proliferation assays, RT-PCR, Western blot, and flow cytometry were used to estimate changes in gene expression and cell proliferation. Ion channel activity was recorded using the patch-clamp technique. Specific genes were knocked-down by siRNA assays. RESULTS VRAC, identified as a hypotonicity-induced current, was highly functional and associated with the proliferation of HST-1 cells but not of HaCaT (a normal keratinocyte) cells. The pharmacological profile of VRAC in HST-1 was similar to that reported previously. DCPIB, a specific VRAC inhibitor, completely inhibited VRAC and proliferation of HST-1 cells, eventually leading to apoptosis. VRAC in HST-1 was attenuated by the knockdown of TMEM16A and LRRC8A, while knockdown of BEST1 affected cell proliferation. In situ proximity ligation assay showed that TMEM16A and LRRC8A co-localized under isotonic conditions (300 mOsM) but were separated under hypotonic conditions (250 mOsM) on the plasma membrane. CONCLUSIONS We have found that VRAC acts to regulate the proliferation of human metastatic OSCC cells and the composition of VRAC may involve in the interactions between TMEM16A and LRRC8A in HST-1 cells.
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Affiliation(s)
- Shohei Yoshimoto
- Section of Pathology, Department of Morphological Biology, Fukuoka Dental College, Fukuoka 8140193, Japan; Oral Medicine Research Center, Fukuoka Dental College, Fukuoka 8140193, Japan
| | - Miho Matsuda
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 8128582, Japan
| | - Kenichi Kato
- Department of Nursing, Fukuoka School of Health Sciences, Fukuoka 8140005, Japan
| | - Eijiro Jimi
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 8128582, Japan; Oral Health/Brain Health/Total Health Research Center, Graduate School of Dental Science, Kyushu University, Fukuoka 8128582, Japan
| | - Hiroshi Takeuchi
- Department of Applied Pharmacology, Graduate School of Dentistry, Kyushu Dental University, Fukuoka 8038580, Japan
| | - Shuji Nakano
- Graduate School of Health and Nutritional Sciences, Nakamura Gakuen University, Fukuoka 8140198, Japan
| | - Shunichi Kajioka
- Department of Pharmacy in Fukuoka, International University of Health and Welfare, Fukuoka 8318501, Japan
| | - Etsuko Matsuzaki
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka 8140193, Japan; Operative Dentistry and Endodontology, Department of Odontology, Fukuoka Dental College, Fukuoka 8140193, Japan
| | - Takao Hirofuji
- Section of General Dentistry, Department of General Dentistry, Fukuoka Dental College, Fukuoka 8140193, Japan
| | - Ryuji Inoue
- Department of Physiology, Graduate School of Medical Science, Fukuoka University, Fukuoka 8140180, Japan
| | - Masato Hirata
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka 8140193, Japan
| | - Hiromitsu Morita
- The Center for Visiting Dental Service, Department of General Dentistry, Fukuoka Dental College, Fukuoka 8140193, Japan.
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Lee-Rivera I, López E, Alvarez-Arce A, López-Colomé AM. The PKC-ζ pseudosubstrate peptide induces glutamate release from retinal pigment epithelium cells through kinase- independent activation of Best1. Life Sci 2020; 265:118860. [PMID: 33301813 DOI: 10.1016/j.lfs.2020.118860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/19/2020] [Accepted: 12/01/2020] [Indexed: 10/22/2022]
Abstract
AIMS The retinal pigment epithelium (RPE) is a highly specialized cell monolayer, that plays a key role in the maintenance of photoreceptor function and the blood-retina barrier (BRB). In this study, we found that a myristoylated pseudosubstrate of PKC-ζ (PKCζ PS), considered as a PKC-ζ inhibitor, plays a distinct role in RPE. MAIN METHODS We demonstrated that PKCζ PS stimulates the release of Glutamate (Glu) using in vitro3H-Glutamate release experiments. By western blot, kinase assays, and Fluoresence Ca+2 Concentration Measurements, we determined the cellular mechanisms involved in such release. KEY FINDINGS Surprisingly, PKCζ PS has no effect on either phosphorylation of T560, essential for catalytic activity, nor it has an effect on kinase activity. It induces the dose-dependent release of Glu by increasing intracellular Ca+2 levels. Interestingly, this release was not observed upon stimulation by other non-competitive PKC-ζ inhibitors. We here demonstrated that the PKCζ PS stimulates the release of Glutamate from RPE by activating the Ca2+-dependent Cl channel Bestrophin 1 (Best1). SIGNIFICANCE These results question PKCζ PS specificity as an inhibitor of this enzyme. Furthermore, the present results underline the relevance of clarifying the molecular mechanisms involved in glutamate release from the retina under conditions derived from excitotoxic stimuli.
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Affiliation(s)
- Irene Lee-Rivera
- Department of Molecular Neuropathology, Instituto de Fisiología Celular, UNAM, Apartado Postal 70-253, Ciudad Universitaria, México City, CdMx, Mexico
| | - Edith López
- Department of Molecular Neuropathology, Instituto de Fisiología Celular, UNAM, Apartado Postal 70-253, Ciudad Universitaria, México City, CdMx, Mexico
| | - Alejandro Alvarez-Arce
- Department of Molecular Neuropathology, Instituto de Fisiología Celular, UNAM, Apartado Postal 70-253, Ciudad Universitaria, México City, CdMx, Mexico
| | - Ana María López-Colomé
- Department of Molecular Neuropathology, Instituto de Fisiología Celular, UNAM, Apartado Postal 70-253, Ciudad Universitaria, México City, CdMx, Mexico.
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Biasella F, Plössl K, Karl C, Weber BHF, Friedrich U. Altered Protein Function Caused by AMD-associated Variant rs704 Links Vitronectin to Disease Pathology. Invest Ophthalmol Vis Sci 2020; 61:2. [PMID: 33259607 PMCID: PMC7718807 DOI: 10.1167/iovs.61.14.2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 11/07/2020] [Indexed: 12/13/2022] Open
Abstract
Purpose Vitronectin, a cell adhesion and spreading factor, is suspected to play a role in the pathogenesis of age-related macular degeneration (AMD), as it is a major component of AMD-specific extracellular deposits (e.g., soft drusen, subretinal drusenoid deposits). The present study addressed the impact of AMD-associated non-synonymous variant rs704 in the vitronectin-encoding gene VTN on vitronectin functionality. Methods Effects of rs704 on vitronectin expression and processing were analyzed by semi-quantitative sequencing of VTN transcripts from retinal pigment epithelium (RPE) cells generated from human induced pluripotent stem cells (hiPSCs) and from human neural retina, as well as by western blot analyses on heterologously expressed vitronectin isoforms. Binding of vitronectin isoforms to retinal and endothelial cells was analyzed by western blot. Immunofluorescence staining followed extracellular matrix (ECM) deposition in cultured RPE cells heterologously expressing the vitronectin isoforms. Adhesion of fluorescently labeled RPE or endothelial cells in dependence of recombinant vitronectin or vitronectin-containing ECM was investigated fluorometrically or microscopically. Tube formation and migration assays addressed effects of vitronectin on angiogenesis-related processes. Results Variant rs704 affected expression, secretion, and processing but not oligomerization of vitronectin. Cell binding and influence on RPE-mediated ECM deposition differed between AMD-risk-associated and non-AMD-risk-associated protein isoforms. Finally, vitronectin affected adhesion and endothelial tube formation. Conclusions The AMD-risk-associated vitronectin isoform exhibits increased expression and altered functionality in cellular processes related to the sub-RPE aspects of AMD pathology. Although further research is required to address the subretinal disease aspects, this initial study supports an involvement of vitronectin in AMD pathogenesis.
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Affiliation(s)
- Fabiola Biasella
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Karolina Plössl
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Claudia Karl
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Bernhard H. F. Weber
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
- Institute of Clinical Human Genetics, University Hospital Regensburg, Regensburg, Germany
| | - Ulrike Friedrich
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
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Coussa RG, Binkley EM, Wilkinson ME, Andorf JL, Tucker BA, Mullins RF, Sohn EH, Yannuzzi LA, Stone EM, Han IC. Predominance of hyperopia in autosomal dominant Best vitelliform macular dystrophy. Br J Ophthalmol 2020; 106:522-527. [DOI: 10.1136/bjophthalmol-2020-317763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/05/2020] [Accepted: 11/15/2020] [Indexed: 12/17/2022]
Abstract
Background/AimsPatients with BEST1-associated autosomal dominant Best vitelliform macular dystrophy (AD-BVMD) have been reported to be hyperopic, but the prevalence of refractive error has not been described. This study aimed to characterise the type and degree of refractive error in a large cohort of patients with AD-BVMD compared with an age-similar group with ABCA4-associated Stargardt disease.MethodsThis was a retrospective chart review of consecutive patients with molecularly confirmed AD-BVMD and Stargardt macular dystrophy seen at a single academic centre. Demographic information, including age, gender and genotype were extracted from the chart. The best corrected visual acuity (BCVA), as well as type and degree of refractive error on manifest refraction for each eye on each visit, were recorded and compared.ResultsA total of 178 eyes from 89 patients with AD-BVMD (35 women, 54 men; mean age 36.6 years) and 306 eyes from 153 patients (94 women, 59 men, mean age 30.2 years) with Stargardt disease were included in the study. Mean BCVA was excellent for both AD-BVMD and Stargardt eyes (logMAR 0.23 vs logMAR 0.31, respectively; p=0.55). At initial refraction, 73.0% of AD-BVMD eyes (130/178) were hyperopic, with mean spherical equivalent (SE) +1.38 dioptres (median +0.88) whereas 80.7% of Stargardt eyes (247/306) were myopic, with mean SE of −1.76 dioptres (median −1.19) (p<0.001).ConclusionPatients with AD-BVMD are predominantly hyperopic, whereas those with Stargardt disease are predominantly myopic. The findings provide further evidence of a role for BEST1 in ocular growth and development.
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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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12
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Lima de Carvalho JR, Paavo M, Chen L, Chiang J, Tsang SH, Sparrow JR. Multimodal Imaging in Best Vitelliform Macular Dystrophy. Invest Ophthalmol Vis Sci 2019; 60:2012-2022. [PMID: 31070670 PMCID: PMC6735800 DOI: 10.1167/iovs.19-26571] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Purpose In patients diagnosed with Best vitelliform macular dystrophy (BVMD), quantitative fundus autofluorescence (qAF), near-infrared fundus autofluorescence (NIR-AF), and spectral-domain optical coherence tomography (SD-OCT) were used to elucidate pathogenic mechanisms. Methods Fourteen patients heterozygous for BEST1 mutations were recruited. qAF was analyzed using short-wavelength fundus autofluorescence (SW-AF) images. Mean gray levels (GL) were determined in nonlesion areas (7 to 9° eccentricity) and adjusted by GL measured in an internal fluorescent reference. NIR-AF images (787 nm; sensitivity of 96) were captured and saved in non-normalized mode. Horizontal SD-OCT images also were acquired and BVMD was staged according to the OCT findings. Results In the pre-vitelliform stage, NIR-AF imaging revealed an area of reduced fluorescence, whereas in the vitelliruptive stage, puncta of elevated NIR-AF signal were present. In both SW-AF and NIR-AF images, the vitelliform lesion in the atrophic stage was marked by reduced signal. At all stages of BVMD, nonlesion qAF was within the 95% confidence intervals for healthy eyes. Similarly, the NIR-AF intensity measurements outside the vitelliform lesion were comparable to the healthy control eye. SD-OCT scans revealed a fluid-filled detachment between the ellipsoid zone and the hyperreflectivity band attributable to RPE/Bruch's membrane. Conclusions NIR-AF imaging can identify the pre-vitelliform stage of BVMD. Mutations in BEST1 are not associated with increased levels of SW-AF outside the vitelliform lesion. Elevated SW-AF within the fluid-filled lesion likely reflects the inability of RPE to phagocytose outer segments due to separation of RPE from photoreceptor cells, together with progressive photoreceptor cell impairment.
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Affiliation(s)
- Jose Ronaldo Lima de Carvalho
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States.,Department of Ophthalmology, Empresa Brasileira de Servicos Hospitalares (EBSERH) - Hospital das Clinicas de Pernambuco (HCPE), Federal University of Pernambuco (UFPE), Recife, Brazil.,Department of Ophthalmology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Maarjaliis Paavo
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States
| | - Lijuan Chen
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States.,Department of Ophthalmology, People's Hospital of PuTuo District, Shanghai, China
| | - John Chiang
- Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, United States
| | - Stephen H Tsang
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, New York, United States
| | - Janet R Sparrow
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, New York, United States
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13
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Lessons learned from quantitative fundus autofluorescence. Prog Retin Eye Res 2019; 74:100774. [PMID: 31472235 DOI: 10.1016/j.preteyeres.2019.100774] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 08/21/2019] [Accepted: 08/25/2019] [Indexed: 12/12/2022]
Abstract
Quantitative fundus autofluorescence (qAF) is an approach that is built on a confocal scanning laser platform and used to measure the intensity of the inherent autofluorescence of retina elicited by short-wavelength (488 nm) excitation. Being non-invasive, qAF does not interrupt tissue architecture, thus allowing for structural correlations. The spectral features, cellular origin and topographic distribution of the natural autofluorescence of the fundus indicate that it is emitted from retinaldehyde-adducts that form in photoreceptor cells and accumulate, under most conditions, in retinal pigment epithelial cells. The distributions and intensities of fundus autofluorescence deviate from normal in many retinal disorders and it is widely recognized that these changing patterns can aid in the diagnosis and monitoring of retinal disease. The standardized protocol employed by qAF involves the normalization of fundus grey levels to a fluorescent reference installed in the imaging instrument. Together with corrections for magnification and anterior media absorption, this approach facilitates comparisons with serial images and images acquired within groups of patients. Here we provide a comprehensive summary of the principles and practice of qAF and we highlight recent efforts to elucidate retinal disease processes by combining qAF with multi-modal imaging.
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14
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Okada Y, Okada T, Sato-Numata K, Islam MR, Ando-Akatsuka Y, Numata T, Kubo M, Shimizu T, Kurbannazarova RS, Marunaka Y, Sabirov RZ. Cell Volume-Activated and Volume-Correlated Anion Channels in Mammalian Cells: Their Biophysical, Molecular, and Pharmacological Properties. Pharmacol Rev 2019; 71:49-88. [PMID: 30573636 DOI: 10.1124/pr.118.015917] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
There are a number of mammalian anion channel types associated with cell volume changes. These channel types are classified into two groups: volume-activated anion channels (VAACs) and volume-correlated anion channels (VCACs). VAACs can be directly activated by cell swelling and include the volume-sensitive outwardly rectifying anion channel (VSOR), which is also called the volume-regulated anion channel; the maxi-anion channel (MAC or Maxi-Cl); and the voltage-gated anion channel, chloride channel (ClC)-2. VCACs can be facultatively implicated in, although not directly activated by, cell volume changes and include the cAMP-activated cystic fibrosis transmembrane conductance regulator (CFTR) anion channel, the Ca2+-activated Cl- channel (CaCC), and the acid-sensitive (or acid-stimulated) outwardly rectifying anion channel. This article describes the phenotypical properties and activation mechanisms of both groups of anion channels, including accumulating pieces of information on the basis of recent molecular understanding. To that end, this review also highlights the molecular identities of both anion channel groups; in addition to the molecular identities of ClC-2 and CFTR, those of CaCC, VSOR, and Maxi-Cl were recently identified by applying genome-wide approaches. In the last section of this review, the most up-to-date information on the pharmacological properties of both anion channel groups, especially their half-maximal inhibitory concentrations (IC50 values) and voltage-dependent blocking, is summarized particularly from the standpoint of pharmacological distinctions among them. Future physiologic and pharmacological studies are definitely warranted for therapeutic targeting of dysfunction of VAACs and VCACs.
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Affiliation(s)
- Yasunobu Okada
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Toshiaki Okada
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Kaori Sato-Numata
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Md Rafiqul Islam
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Yuhko Ando-Akatsuka
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Tomohiro Numata
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Machiko Kubo
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Takahiro Shimizu
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Ranohon S Kurbannazarova
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Yoshinori Marunaka
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Ravshan Z Sabirov
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
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15
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Constable PA, Ngo D. The slow light and dark oscillation of the clinical electro-oculogram. Clin Exp Optom 2018; 101:786-792. [PMID: 29781186 DOI: 10.1111/cxo.12799] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 04/20/2018] [Accepted: 04/23/2018] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The standing potential of the eye exhibits a slow damped oscillation under light and dark conditions that continues for at least 80 minutes. However, our understanding of the relationship between the slow dark and light oscillation has not been previously studied. The aim of this study was to explore through regression analysis a model of these oscillations in order to establish if they may have the same underlying cellular generators. METHODS Healthy participants undertook recordings of the standing potential using the electro-oculogram for 100 minutes. To explore the light oscillation, participants (n = 8) were dilated and performed an extended electro-oculogram protocol consisting of 15 minutes dark adaptation and 85 minutes of white light adaptation at 100 cd/m2 . For the dark oscillation, participants (n = 11) undertook the electro-oculogram for 100 minutes in complete darkness. Both sessions began with pre-adaptation to 30 cd/m2 of white light for five minutes. Non-parametric statistics were used to evaluate all data. RESULTS Ratios of the dark and light oscillations showed a significantly greater dampening of the dark oscillation compared to the light oscillation (p < 0.000). Regression analysis using a five-factor damped sine function revealed significant differences in the parameters governing the dampening (p = 0.005) and period (p = 0.009) of the functions (R2 > 0.874). There were no significant differences in the dark trough amplitude. CONCLUSION The results support a different underlying physiological mechanism for the light and dark oscillation of the clinical electro-oculogram. Future work will need to establish how the dark oscillation and dark trough of the clinical electro-oculogram arise.
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Affiliation(s)
- Paul A Constable
- College of Nursing and Health Sciences, Flinders University, Adelaide, South Australia, Australia
| | - David Ngo
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
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16
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Gómez NM, Lu W, Lim JC, Kiselyov K, Campagno KE, Grishchuk Y, Slaugenhaupt SA, Pfeffer BA, Fliesler SJ, Mitchell CH. Robust lysosomal calcium signaling through channel TRPML1 is impaired by lysosomal lipid accumulation. FASEB J 2018; 32:782-794. [PMID: 29030399 PMCID: PMC5888396 DOI: 10.1096/fj.201700220rr] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 09/26/2017] [Indexed: 12/20/2022]
Abstract
The transient receptor potential cation channel mucolipin 1 (TRPML1) channel is a conduit for lysosomal calcium efflux, and channel activity may be affected by lysosomal contents. The lysosomes of retinal pigmented epithelial (RPE) cells are particularly susceptible to build-up of lysosomal waste products because they must degrade the outer segments phagocytosed daily from adjacent photoreceptors; incomplete degradation leads to accumulation of lipid waste in lysosomes. This study asks whether stimulation of TRPML1 can release lysosomal calcium in RPE cells and whether such release is affected by lysosomal accumulations. The TRPML agonist ML-SA1 raised cytoplasmic calcium levels in mouse RPE cells, hesRPE cells, and ARPE-19 cells; this increase was rapid, robust, reversible, and reproducible. The increase was not altered by extracellular calcium removal or by thapsigargin but was eliminated by lysosomal rupture with glycyl-l-phenylalanine-β-naphthylamide. Treatment with desipramine to inhibit acid sphingomyelinase or YM201636 to inhibit PIKfyve also reduced the cytoplasmic calcium increase triggered by ML-SA1, whereas RPE cells from TRPML1-/- mice showed no response to ML-SA1. Cotreatment with chloroquine and U18666A induced formation of neutral, autofluorescent lipid in RPE lysosomes and decreased lysosomal Ca2+ release. Lysosomal Ca2+ release was also impaired in RPE cells from the ATP-binding cassette, subfamily A, member 4-/- mouse model of Stargardt's retinal dystrophy. Neither TRPML1 mRNA nor total lysosomal calcium levels were altered in these models, suggesting a more direct effect on the channel. In summary, stimulation of TRPML1 elevates cytoplasmic calcium levels in RPE cells, but this response is reduced by lysosomal accumulation.-Gómez, N. M., Lu, W. Lim, J. C., Kiselyov, K., Campagno, K. E., Grishchuk, Y., Slaugenhaupt, S. A., Pfeffer, B., Fliesler, S. J., Mitchell, C. H. Robust lysosomal calcium signaling through channel TRPML1 is impaired by lysosomal lipid accumulation.
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Affiliation(s)
- Néstor Más Gómez
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wennan Lu
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jason C. Lim
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kirill Kiselyov
- Department of Biological Science, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Keith E. Campagno
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yulia Grishchuk
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, USA
- Department of Neurology, Massachusetts General Hospital Research Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Susan A. Slaugenhaupt
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, USA
- Department of Neurology, Massachusetts General Hospital Research Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Bruce A. Pfeffer
- Department of Ophthalmology, Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY)–University at Buffalo, Buffalo, New York, USA
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY)–University at Buffalo, Buffalo, New York, USA
- State University of New York (SUNY)–Eye Institute, Buffalo, New York, USA
- Research Service, Veterans Affairs Western New York Healthcare System, Buffalo, New York, USA
| | - Steven J. Fliesler
- Department of Ophthalmology, Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY)–University at Buffalo, Buffalo, New York, USA
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY)–University at Buffalo, Buffalo, New York, USA
- State University of New York (SUNY)–Eye Institute, Buffalo, New York, USA
- Research Service, Veterans Affairs Western New York Healthcare System, Buffalo, New York, USA
| | - Claire H. Mitchell
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Li Y, Zhang Y, Xu Y, Kittredge A, Ward N, Chen S, Tsang SH, Yang T. Patient-specific mutations impair BESTROPHIN1's essential role in mediating Ca 2+-dependent Cl - currents in human RPE. eLife 2017; 6. [PMID: 29063836 PMCID: PMC5655127 DOI: 10.7554/elife.29914] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 09/13/2017] [Indexed: 01/06/2023] Open
Abstract
Mutations in the human BEST1 gene lead to retinal degenerative diseases displaying progressive vision loss and even blindness. BESTROPHIN1, encoded by BEST1, is predominantly expressed in retinal pigment epithelium (RPE), but its physiological role has been a mystery for the last two decades. Using a patient-specific iPSC-based disease model and interdisciplinary approaches, we comprehensively analyzed two distinct BEST1 patient mutations, and discovered mechanistic correlations between patient clinical phenotypes, electrophysiology in their RPEs, and the structure and function of BESTROPHIN1 mutant channels. Our results revealed that the disease-causing mechanism of BEST1 mutations is centered on the indispensable role of BESTROPHIN1 in mediating the long speculated Ca2+-dependent Cl- current in RPE, and demonstrate that the pathological potential of BEST1 mutations can be evaluated and predicted with our iPSC-based 'disease-in-a-dish' approach. Moreover, we demonstrated that patient RPE is rescuable with viral gene supplementation, providing a proof-of-concept for curing BEST1-associated diseases.
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Affiliation(s)
- Yao Li
- Jonas Children's Vision Care, and Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology and Pathology & Cell Biology, Edward S. Harkness Eye Institute, New York Presbyterian Hospital/Columbia University, New York, United States
| | - Yu Zhang
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, Rochester, United States
| | - Yu Xu
- Jonas Children's Vision Care, and Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology and Pathology & Cell Biology, Edward S. Harkness Eye Institute, New York Presbyterian Hospital/Columbia University, New York, United States.,Department of Ophthalmology, Xinhua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Alec Kittredge
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, Rochester, United States
| | - Nancy Ward
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, Rochester, United States
| | - Shoudeng Chen
- Molecular Imaging Center, Department of Experimental Medicine, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China
| | - Stephen H Tsang
- Jonas Children's Vision Care, and Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology and Pathology & Cell Biology, Edward S. Harkness Eye Institute, New York Presbyterian Hospital/Columbia University, New York, United States
| | - Tingting Yang
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, Rochester, United States
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18
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Abstract
PURPOSE To evaluate the electrooculogram (EOG) in a large series of patients with Best disease and autosomal recessive bestrophinopathy. METHODS A retrospective review of consecutive cases at Moorfields Eye Hospital, London, United Kingdom. Patients with Best disease or autosomal recessive bestrophinopathy who, after electrophysiologic testing, had a normal or atypical EOG light rise were identified. Main outcome measure was EOG amplitude, clinical phenotype and genotype. RESULTS One hundred thirteen patients were identified with likely disease-causing sequence variants in BEST1 (99 Best disease and 14 autosomal recessive bestrophinopathy). Electrooculograms had been performed in 75 patients. Twenty patients (27%) had no detectable light rise (Arden ratio of 100%) and 49 (65%) had Arden ratios of between 100% to 165%. Six patients (8%) were found to have an EOG light rise of >165%. No cases demonstrated significant interocular asymmetry in EOG amplitude. CONCLUSION The current work provides significant clinical evidence that the EOG phenotype in Best disease and autosomal recessive bestrophinopathy is more variable than currently appreciated. As a normal EOG may occur in the presence of a classical fundus appearance, the consequences of BEST1 mutation may be independently expressed, possibly mediated through differential effects on intracellular calcium homeostasis.
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19
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Guziewicz KE, Sinha D, Gómez NM, Zorych K, Dutrow EV, Dhingra A, Mullins RF, Stone EM, Gamm DM, Boesze-Battaglia K, Aguirre GD. Bestrophinopathy: An RPE-photoreceptor interface disease. Prog Retin Eye Res 2017; 58:70-88. [PMID: 28111324 PMCID: PMC5441932 DOI: 10.1016/j.preteyeres.2017.01.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/16/2017] [Accepted: 01/18/2017] [Indexed: 11/17/2022]
Abstract
Bestrophinopathies, one of the most common forms of inherited macular degenerations, are caused by mutations in the BEST1 gene expressed in the retinal pigment epithelium (RPE). Both human and canine BEST1-linked maculopathies are characterized by abnormal accumulation of autofluorescent material within RPE cells and bilateral macular or multifocal lesions; however, the specific mechanism leading to the formation of these lesions remains unclear. We now provide an overview of the current state of knowledge on the molecular pathology of bestrophinopathies, and explore factors promoting formation of RPE-neuroretinal separations, using the first spontaneous animal model of BEST1-associated retinopathies, canine Best (cBest). Here, we characterize the nature of the autofluorescent RPE cell inclusions and report matching spectral signatures of RPE-associated fluorophores between human and canine retinae, indicating an analogous composition of endogenous RPE deposits in Best Vitelliform Macular Dystrophy (BVMD) patients and its canine disease model. This study also exposes a range of biochemical and structural abnormalities at the RPE-photoreceptor interface related to the impaired cone-associated microvillar ensheathment and compromised insoluble interphotoreceptor matrix (IPM), the major pathological culprits responsible for weakening of the RPE-neuroretina interactions, and consequently, formation of vitelliform lesions. These salient alterations detected at the RPE apical domain in cBest as well as in BVMD- and ARB-hiPSC-RPE model systems provide novel insights into the pathological mechanism of BEST1-linked disorders that will allow for development of critical outcome measures guiding therapeutic strategies for bestrophinopathies.
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Affiliation(s)
- Karina E Guziewicz
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA.
| | - Divya Sinha
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Néstor M Gómez
- Department of Anatomy & Cell Biology, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
| | - Kathryn Zorych
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
| | - Emily V Dutrow
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
| | - Anuradha Dhingra
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
| | - Robert F Mullins
- Department of Ophthalmology & Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Edwin M Stone
- Department of Ophthalmology & Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - David M Gamm
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Ophthalmology & Visual Sciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | | | - Gustavo D Aguirre
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
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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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Schreiber R, Kunzelmann K. Expression of anoctamins in retinal pigment epithelium (RPE). Pflugers Arch 2016; 468:1921-1929. [PMID: 27822608 DOI: 10.1007/s00424-016-1898-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 10/17/2016] [Accepted: 10/19/2016] [Indexed: 01/24/2023]
Abstract
The anoctamin (ANO, TMEM16) family of Ca2+-activated Cl- channels consists of ten members with different cellular functions (ANO1-10). ANO1 is a Ca2+-activated Cl- channel in secretory epithelial cells of exocrine pancreas, salivary glands, or enterocytes. Expression of ANO1 also promotes cell proliferation and migration of tumor cells. ANO6 is essential for Ca2+-dependent scrambling of membrane phospholipids in platelets, red blood cells, and lymphocytes. ANO10 modulates Ca2+ signals in macrophages and has a role in cerebellar ataxia and other neurological disorders. All three anoctamins have been proposed to control intracellular Ca2+ signals. Anoctamins may also form the basolateral Ca2+-activated Cl- channel in the retinal pigment epithelium (RPE). We show that native human, bovine, porcine, and mouse RPEs express ANO1, ANO6, and ANO10. Growth arrested and confluent RPR cells expressed ANO1 in the plasma membrane, whereas ANO6 and ANO10 were found in the primary cilium. Ussing chamber experiments showed that the application of ATP to the apical (retinal) side of porcine RPE induced a Ca2+-activated Cl- secretion. Activation was inhibited by basolateral (choroidal) administration of the ANO inhibitors AO1, niflumic acid (NFA), and 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS). The results suggest that ANO1 is responsible for basolateral Ca2+-dependent Cl- secretion in RPE, whereas ANO6 and ANO10 may have different functions, such as modulating Ca2+ signals.
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Affiliation(s)
- Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
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22
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Unilateral BEST1-Associated Retinopathy. Am J Ophthalmol 2016; 169:24-32. [PMID: 27287821 PMCID: PMC5016077 DOI: 10.1016/j.ajo.2016.05.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 05/16/2016] [Accepted: 05/31/2016] [Indexed: 11/22/2022]
Abstract
Purpose To describe a series of patients with molecularly confirmed mutation in BEST1 causing Best disease but with unilateral clinical manifestation. Design Retrospective observational case series. Methods Setting: Moorfields Eye Hospital and Great Ormond Street Hospital, London (United Kingdom). Patients: Five patients (10 eyes) with uniocular manifestation of BEST1 mutation causing Best disease were ascertained retrospectively from the clinical and genetic databases. Main Outcome Measures: Patients had full ophthalmologic examination, color fundus photography, fundus autofluorescence imaging, spectral-domain optical coherence tomography, and detailed electrophysiological assessment. Genetic testing was performed. Results All cases had a clinical appearance typical of and consistent with Best disease at various stages, except that the presentation was unilateral. The reduced electrooculogram light rise was bilateral and in the context of normal electroretinograms therefore indicates generalized dysfunction at the level of the retinal pigment epithelium. Conclusions Mutation in BEST1 has variable penetrance and expressivity, and can be uniocular. The clinical and electrophysiological features described assist targeted mutational screening and alert to the potential diagnosis even when there is an atypical unilateral presentation.
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Farnoodian M, Halbach C, Slinger C, Pattnaik BR, Sorenson CM, Sheibani N. High glucose promotes the migration of retinal pigment epithelial cells through increased oxidative stress and PEDF expression. Am J Physiol Cell Physiol 2016; 311:C418-36. [PMID: 27440660 DOI: 10.1152/ajpcell.00001.2016] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 07/18/2016] [Indexed: 12/11/2022]
Abstract
Defects in the outer blood-retinal barrier have significant impact on the pathogenesis of diabetic retinopathy and macular edema. However, the detailed mechanisms involved remain largely unknown. This is, in part, attributed to the lack of suitable animal and cell culture models, including those of mouse origin. We recently reported a method for the culture of retinal pigment epithelial (RPE) cells from wild-type and transgenic mice. The RPE cells are responsible for maintaining the integrity of the outer blood-retinal barrier whose dysfunction during diabetes has a significant impact on vision. Here we determined the impact of high glucose on the function of RPE cells. We showed that high glucose conditions resulted in enhanced migration and increased the level of oxidative stress in RPE cells, but minimally impacted their rate of proliferation and apoptosis. High glucose also minimally affected the cell-matrix and cell-cell interactions of RPE cells. However, the expression of integrins and extracellular matrix proteins including pigment epithelium-derived factor (PEDF) were altered under high glucose conditions. Incubation of RPE cells with the antioxidant N-acetylcysteine under high glucose conditions restored normal migration and PEDF expression. These cells also exhibited increased nuclear localization of the antioxidant transcription factor Nrf2 and ZO-1, reduced levels of β-catenin and phagocytic activity, and minimal effect on production of vascular endothelial growth factor, inflammatory cytokines, and Akt, MAPK, and Src signaling pathways. Thus high glucose conditions promote RPE cell migration through increased oxidative stress and expression of PEDF without a significant effect on the rate of proliferation and apoptosis.
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Affiliation(s)
- Mitra Farnoodian
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Caroline Halbach
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Cassidy Slinger
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Bikash R Pattnaik
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; and
| | - Christine M Sorenson
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; and
| | - Nader Sheibani
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; and Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
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24
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Cook DP, Rector MV, Bouzek DC, Michalski AS, Gansemer ND, Reznikov LR, Li X, Stroik MR, Ostedgaard LS, Abou Alaiwa MH, Thompson MA, Prakash YS, Krishnan R, Meyerholz DK, Seow CY, Stoltz DA. Cystic Fibrosis Transmembrane Conductance Regulator in Sarcoplasmic Reticulum of Airway Smooth Muscle. Implications for Airway Contractility. Am J Respir Crit Care Med 2016; 193:417-26. [PMID: 26488271 DOI: 10.1164/rccm.201508-1562oc] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE An asthma-like airway phenotype has been described in people with cystic fibrosis (CF). Whether these findings are directly caused by loss of CF transmembrane conductance regulator (CFTR) function or secondary to chronic airway infection and/or inflammation has been difficult to determine. OBJECTIVES Airway contractility is primarily determined by airway smooth muscle. We tested the hypothesis that CFTR is expressed in airway smooth muscle and directly affects airway smooth muscle contractility. METHODS Newborn pigs, both wild type and with CF (before the onset of airway infection and inflammation), were used in this study. High-resolution immunofluorescence was used to identify the subcellular localization of CFTR in airway smooth muscle. Airway smooth muscle function was determined with tissue myography, intracellular calcium measurements, and regulatory myosin light chain phosphorylation status. Precision-cut lung slices were used to investigate the therapeutic potential of CFTR modulation on airway reactivity. MEASUREMENTS AND MAIN RESULTS We found that CFTR localizes to the sarcoplasmic reticulum compartment of airway smooth muscle and regulates airway smooth muscle tone. Loss of CFTR function led to delayed calcium reuptake following cholinergic stimulation and increased myosin light chain phosphorylation. CFTR potentiation with ivacaftor decreased airway reactivity in precision-cut lung slices following cholinergic stimulation. CONCLUSIONS Loss of CFTR alters porcine airway smooth muscle function and may contribute to the airflow obstruction phenotype observed in human CF. Airway smooth muscle CFTR may represent a therapeutic target in CF and other diseases of airway narrowing.
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Affiliation(s)
- Daniel P Cook
- 1 Department of Internal Medicine.,2 Department of Molecular Physiology and Biophysics
| | | | | | | | | | | | | | | | | | | | - Michael A Thompson
- 3 Department of Anesthesiology and.,4 Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Y S Prakash
- 3 Department of Anesthesiology and.,4 Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Ramaswamy Krishnan
- 5 Department of Emergency Medicine, Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Boston, Massachusetts; and
| | | | - Chun Y Seow
- 7 Department of Pathology and Laboratory Medicine, James Hogg Research Centre/St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - David A Stoltz
- 1 Department of Internal Medicine.,2 Department of Molecular Physiology and Biophysics.,8 Department of Biomedical Engineering, and.,9 Pappajohn Biomedical Institute, University of Iowa, Iowa City, Iowa
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Wu L, Sun Y, Ma L, Zhu J, Zhang B, Pan Q, Li Y, Liu H, Diao A, Li Y. A C-terminally truncated mouse Best3 splice variant targets and alters the ion balance in lysosome-endosome hybrids and the endoplasmic reticulum. Sci Rep 2016; 6:27332. [PMID: 27265833 PMCID: PMC4893618 DOI: 10.1038/srep27332] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/16/2016] [Indexed: 02/07/2023] Open
Abstract
The Bestrophin family has been characterized as Cl(-) channels in mammals and Na(+) channels in bacteria, but their exact physiological roles remian unknown. In this study, a natural C-terminally truncated variant of mouse Bestrophin 3 (Best3V2) expression in myoblasts and muscles is demonstrated. Unlike full-length Best3, Best3V2 targets the two important intracellular Ca stores: the lysosome and the ER. Heterologous overexpression leads to lysosome swelling and renders it less acidic. Best3V2 overexpression also results in compromised Ca(2+) release from the ER. Knocking down endogenous Best3 expression in myoblasts makes these cells more excitable in response to Ca(2+) mobilizing reagents, such as caffeine. We propose that Best3V2 in myoblasts may work as a tuner to control Ca(2+) release from intracellular Ca(2+) stores.
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Affiliation(s)
- Lichang Wu
- Department of Animal Sciences and Technology, Qingdao Agricultural University, Qingdao, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Yu Sun
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Liqiao Ma
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Jun Zhu
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Baoxia Zhang
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Qingjie Pan
- Department of Animal Sciences and Technology, Qingdao Agricultural University, Qingdao, China
| | - Yuyin Li
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Huanqi Liu
- Department of Animal Sciences and Technology, Qingdao Agricultural University, Qingdao, China
| | - Aipo Diao
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Yinchuan Li
- Department of Animal Sciences and Technology, Qingdao Agricultural University, Qingdao, China
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Extracellular Calcium Has Multiple Targets to Control Cell Proliferation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:133-56. [DOI: 10.1007/978-3-319-26974-0_7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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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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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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29
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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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Schatz P, Sharon D, Al-Hamdani S, Andréasson S, Larsen M. Retinal structure in young patients aged 10 years or less with Best vitelliform macular dystrophy. Graefes Arch Clin Exp Ophthalmol 2015; 254:215-21. [DOI: 10.1007/s00417-015-3025-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 04/08/2015] [Accepted: 04/20/2015] [Indexed: 11/30/2022] Open
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Activation of endogenously expressed ion channels by active complement in the retinal pigment epithelium. Pflugers Arch 2014; 467:2179-91. [PMID: 25427445 DOI: 10.1007/s00424-014-1656-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 11/07/2014] [Accepted: 11/13/2014] [Indexed: 10/24/2022]
Abstract
Defective regulation of the alternative pathway of the complement system is believed to contribute to damage of retinal pigment epithelial (RPE) cells in age-related macular degeneration. Thus we investigated the effect of complement activation on the RPE cell membrane by analyzing changes in membrane conductance via patch-clamp techniques and Ca(2+) imaging. Exposure of human ARPE-19 cells to complement-sufficient normal human serum (NHS) (25 %) resulted in a biphasic increase in intracellular free Ca(2+) ([Ca(2+)]i); an initial peak followed by sustained Ca(2+) increase. C5- or C7-depleted sera did not fully reproduce the signal generated by NHS. The initial peak of the Ca(2+) response was reduced by sarcoplasmic Ca(2+)-ATPase inhibitor thapsigargin, L-type channel blockers (R)-(+)-BayK8644 and isradipine, transient-receptor-potential (TRP) channel blocker ruthenium-red and ryanodine receptor blocker dantrolene. The sustained phase was carried by CaV1.3 L-type channels via tyrosine-phosphorylation. Changes in [Ca(2+)]I were accompanied by an abrupt hyperpolarization, resulting from a transient increase in membrane conductance, which was absent under extracellular Ca(2+)- or K(+)-free conditions and blocked by (R)-(+)-BayK8644 or paxilline, a maxiK channel inhibitor. Single-channel recordings confirmed the contribution of maxiK channels. Primary porcine RPE cells responded to NHS in a comparable manner. Pre-incubation with NHS reduced H2O2-induced cell death. In summary, in a concerted manner, C3a, C5a and sC5b-9 increased [Ca(2+)]i by ryanodine-receptor-dependent activation of L-type channels in addition to maxi-K channels and TRP channels absent from any insertion of a lytic pore.
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Kane Dickson V, Pedi L, Long SB. Structure and insights into the function of a Ca(2+)-activated Cl(-) channel. Nature 2014; 516:213-8. [PMID: 25337878 DOI: 10.1038/nature13913] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 10/06/2014] [Indexed: 01/22/2023]
Abstract
Bestrophin calcium-activated chloride channels (CaCCs) regulate the flow of chloride and other monovalent anions across cellular membranes in response to intracellular calcium (Ca(2+)) levels. Mutations in bestrophin 1 (BEST1) cause certain eye diseases. Here we present X-ray structures of chicken BEST1-Fab complexes, at 2.85 Å resolution, with permeant anions and Ca(2+). Representing, to our knowledge, the first structure of a CaCC, the eukaryotic BEST1 channel, which recapitulates CaCC function in liposomes, is formed from a pentameric assembly of subunits. Ca(2+) binds to the channel's large cytosolic region. A single ion pore, approximately 95 Å in length, is located along the central axis and contains at least 15 binding sites for anions. A hydrophobic neck within the pore probably forms the gate. Phenylalanine residues within it may coordinate permeating anions via anion-π interactions. Conformational changes observed near the 'Ca(2+) clasp' hint at the mechanism of Ca(2+)-dependent gating. Disease-causing mutations are prevalent within the gating apparatus.
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Affiliation(s)
- Veronica Kane Dickson
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Leanne Pedi
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Stephen B Long
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
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Ion channels and transporters of the retinal pigment epithelium. Exp Eye Res 2014; 126:27-37. [DOI: 10.1016/j.exer.2014.05.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 05/02/2014] [Accepted: 05/12/2014] [Indexed: 12/19/2022]
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Liu Y, Zhang H, Huang D, Qi J, Xu J, Gao H, Du X, Gamper N, Zhang H. Characterization of the effects of Cl⁻ channel modulators on TMEM16A and bestrophin-1 Ca²⁺ activated Cl⁻ channels. Pflugers Arch 2014; 467:1417-1430. [PMID: 25078708 DOI: 10.1007/s00424-014-1572-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 06/13/2014] [Accepted: 06/30/2014] [Indexed: 11/30/2022]
Abstract
The Ca(2+) activated Cl(-) channels (CaCCs) play a multitude of important physiological functions. A number of candidate proteins have been proposed to form CaCC, but only two families, the bestrophins and the TMEM16 proteins, recapitulate the properties of native CaCC in expression systems. Studies of endogenous CaCCs are hindered by the lack of specific pharmacology as most Cl(-) channel modulators lack selectivity and a systematic comparison of the effects of these modulators on TMEM16A and bestrophin is missing. In the present study, we studied seven Cl(-) channel inhibitors: niflumic acid (NFA), NPPB, flufenamic acid (FFA), DIDS, tannic acid, CaCCinh-A01 and T16Ainh-A01 for their effects on TMEM16A and bestrophin-1 (Best1) stably expressed in CHO (Chinese hamster ovary) cells using patch clamp technique. Among seven inhibitors studied, NFA showed highest selectivity for TMEM16A (IC50 of 7.40 ± 0.95 μM) over Best1 (IC50 of 102.19 ± 15.05 μM). In contrast, DIDS displayed a reverse selectivity inhibiting Best1 with IC50 of 3.93 ± 0.73 μM and TMEM16A with IC50 of 548.86 ± 25.57 μM. CaCCinh-A01 was the most efficacious blocker for both TMEM16A and Best1 channels. T16Ainh-A01 partially inhibited TMEM16A currents but had no effect on Best1 currents. Tannic acid, NPPB and FFA had variable intermediate effects. Potentiation of channel activity by some of these modulators and the effects on TMEM16A deactivation kinetics were also described. Characterization of Cl(-) channel modulators for their effects on TMEM16A and Best1 will facilitate future studies of native CaCCs.
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Affiliation(s)
- Yani Liu
- Key Laboratory of Neural and Vascular Biology, Ministry of Education; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijizhuang, Heibei, China
| | - Huiran Zhang
- Key Laboratory of Neural and Vascular Biology, Ministry of Education; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijizhuang, Heibei, China
| | - Dongyang Huang
- Key Laboratory of Neural and Vascular Biology, Ministry of Education; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijizhuang, Heibei, China
| | - Jinlong Qi
- Key Laboratory of Neural and Vascular Biology, Ministry of Education; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijizhuang, Heibei, China
| | - Jiaxi Xu
- Key Laboratory of Neural and Vascular Biology, Ministry of Education; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijizhuang, Heibei, China
| | - Haixia Gao
- Key Laboratory of Neural and Vascular Biology, Ministry of Education; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijizhuang, Heibei, China
| | - Xiaona Du
- Key Laboratory of Neural and Vascular Biology, Ministry of Education; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijizhuang, Heibei, China
| | - Nikita Gamper
- Key Laboratory of Neural and Vascular Biology, Ministry of Education; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijizhuang, Heibei, China.,School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Hailin Zhang
- Key Laboratory of Neural and Vascular Biology, Ministry of Education; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijizhuang, Heibei, China.
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Crowley C, Paterson R, Lamey T, McLaren T, De Roach J, Chelva E, Khan J. Autosomal recessive bestrophinopathy associated with angle-closure glaucoma. Doc Ophthalmol 2014; 129:57-63. [PMID: 24859690 PMCID: PMC4074353 DOI: 10.1007/s10633-014-9444-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 05/12/2014] [Indexed: 11/26/2022]
Abstract
PURPOSE Abnormalities in the BEST1 gene have recently been recognised as causing autosomal recessive bestrophinopathy (ARB). ARB has been noted to have a variable phenotypic presentation, distinct from that of autosomal dominant Best vitelliform macular dystrophy (BVMD). Both conditions are associated with deposits in the retina, a reduced or absent electro-oculography (EOG) light rise, and the risk of developing angle-closure glaucoma. Herein, we describe the clinical and genetic characteristics of a young male diagnosed with ARB associated with angle-closure glaucoma resulting from a novel homozygous mutation in BEST1. METHODS All research involved in this case adhered to the tenets of the Declaration of Helsinki. The proband underwent slitlamp examination, retinal autofluorescence imaging and optical coherence tomography after presenting with deteriorating vision. The findings prompted genetic testing with bi-directional DNA sequencing of coding and flanking intronic regions of BEST1. The proband's family members were subsequently screened. RESULTS A provisional diagnosis of ARB was made based on the findings of subretinal and schitic lesions on fundoscopy and retinal imaging, together with abnormal EOG and electroretinography. Genetic testing identified a novel homozygous mutation in BEST1, c.636+1 G>A. Family members were found to carry one copy of the mutation and had no clinical or electrophysiological evidence of disease. The proband was additionally diagnosed with angle-closure glaucoma requiring topical therapy, peripheral iridotomies and phacoemulsification. CONCLUSIONS Phenotypic overlap, reduced penetrance, variable expressivity and the ongoing discovery of new forms of bestrophinopathies add to the difficulty in distinguishing these retinal diseases. All patients diagnosed with ARB or BVMD should be examined for narrow angles and glaucoma, given their frequent association with these conditions.
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Affiliation(s)
- C Crowley
- Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA, 6009, Australia,
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Roosing S, Thiadens AAHJ, Hoyng CB, Klaver CCW, den Hollander AI, Cremers FPM. Causes and consequences of inherited cone disorders. Prog Retin Eye Res 2014; 42:1-26. [PMID: 24857951 DOI: 10.1016/j.preteyeres.2014.05.001] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 04/29/2014] [Accepted: 05/06/2014] [Indexed: 11/18/2022]
Abstract
Hereditary cone disorders (CDs) are characterized by defects of the cone photoreceptors or retinal pigment epithelium underlying the macula, and include achromatopsia (ACHM), cone dystrophy (COD), cone-rod dystrophy (CRD), color vision impairment, Stargardt disease (STGD) and other maculopathies. Forty-two genes have been implicated in non-syndromic inherited CDs. Mutations in the 5 genes implicated in ACHM explain ∼93% of the cases. On the contrary, only 21% of CRDs (17 genes) and 25% of CODs (8 genes) have been elucidated. The fact that the large majority of COD and CRD-associated genes are yet to be discovered hints towards the existence of unknown cone-specific or cone-sensitive processes. The ACHM-associated genes encode proteins that fulfill crucial roles in the cone phototransduction cascade, which is the most frequently compromised (10 genes) process in CDs. Another 7 CD-associated proteins are required for transport processes towards or through the connecting cilium. The remaining CD-associated proteins are involved in cell membrane morphogenesis and maintenance, synaptic transduction, and the retinoid cycle. Further novel genes are likely to be identified in the near future by combining large-scale DNA sequencing and transcriptomics technologies. For 31 of 42 CD-associated genes, mammalian models are available, 14 of which have successfully been used for gene augmentation studies. However, gene augmentation for CDs should ideally be developed in large mammalian models with cone-rich areas, which are currently available for only 11 CD genes. Future research will aim to elucidate the remaining causative genes, identify the molecular mechanisms of CD, and develop novel therapies aimed at preventing vision loss in individuals with CD in the future.
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Affiliation(s)
- Susanne Roosing
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | | | - Carel B Hoyng
- Department of Ophthalmology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology Erasmus Medical Centre, 3000 CA, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Centre, 3000 CA, Rotterdam, The Netherlands
| | - Anneke I den Hollander
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Department of Ophthalmology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
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CaV1.3 L-type channels, maxiK Ca2+-dependent K+ channels and bestrophin-1 regulate rhythmic photoreceptor outer segment phagocytosis by retinal pigment epithelial cells. Cell Signal 2014; 26:968-78. [DOI: 10.1016/j.cellsig.2013.12.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 12/31/2013] [Indexed: 11/20/2022]
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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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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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Duncker T, Greenberg JP, Ramachandran R, Hood DC, Smith RT, Hirose T, Woods RL, Tsang SH, Delori FC, Sparrow JR. Quantitative fundus autofluorescence and optical coherence tomography in best vitelliform macular dystrophy. Invest Ophthalmol Vis Sci 2014; 55:1471-82. [PMID: 24526438 DOI: 10.1167/iovs.13-13834] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Quantitative fundus autofluorescence (qAF), spectral domain optical coherence tomography (SD-OCT) segmentation, and multimodal imaging were performed to elucidate the pathogenesis of Best vitelliform macular dystrophy (BVMD) and to identify abnormalities in lesion versus nonlesion fundus areas. METHODS Sixteen patients with a clinical diagnosis of BVMD were studied. Autofluorescence images (30°, 488-nm excitation) were acquired with a confocal scanning laser ophthalmoscope equipped with an internal fluorescent reference to account for variable laser power and detector sensitivity. The grey levels (GLs) of each image were calibrated to the reference, zero GL, magnification, and normative optical media density, to yield qAF. Horizontal SD-OCT scans were obtained and retinal layers manually segmented. Additionally, color and near-infrared reflectance (NIR-R) images were registered to AF images. All patients were screened for mutations in BEST1. In three additional BVMD patients, in vivo spectrofluorometric measurements were obtained within the vitelliform lesion. RESULTS Mean nonlesion qAF was within normal limits for age. Maximum qAF within the lesion was markedly increased compared with controls. By SD-OCT segmentation, outer segment equivalent thickness was increased and outer nuclear layer thickness decreased in the lesion. Changes were also present in a transition zone beyond the lesion border. In subclinical patients, no abnormalities in retinal layer thickness were identified. Fluorescence spectra recorded from the vitelliform lesion were consistent with those of retinal pigment epithelial cell lipofuscin. CONCLUSIONS Based on qAF, mutations in BEST1 do not cause increased lipofuscin levels in nonlesion fundus areas.
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Affiliation(s)
- Tobias Duncker
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York
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Sharon D, Al-Hamdani S, Engelsberg K, Mizrahi-Meissonnier L, Obolensky A, Banin E, Sander B, Jensen H, Larsen M, Schatz P. Ocular phenotype analysis of a family with biallelic mutations in the BEST1 gene. Am J Ophthalmol 2014; 157:697-709.e1-2. [PMID: 24345323 DOI: 10.1016/j.ajo.2013.12.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/04/2013] [Accepted: 12/04/2013] [Indexed: 10/25/2022]
Abstract
PURPOSE To investigate the genetic cause and perform a comprehensive clinical analysis of a Danish family with autosomal recessive bestrophinopathy; to investigate whether Bestrophin may be expressed in normal human retina. DESIGN Retrospective clinical and molecular genetic analysis and immunohistochemical observational study. METHODS setting: National referral center. participants: A family with 5 individuals and biallelic BEST1 mutations, and enucleated eyes from 2 individuals with nonaffected retinas. observation procedures: Molecular genetic analysis included sequencing of BEST1 and co-segregation analysis. Clinical investigations included electro-oculography, full-field electroretinography, multifocal electroretinography, spectral-domain optical coherence tomography, and fundus autofluorescence imaging. Immunohistochemical analysis was performed. main outcome measures: BEST1 mutations, imaging findings, electroretinography amplitudes, and implicit times. RESULTS The index case was compound heterozygous for p.A195V and a novel 15 base pair deletion leading to p.Q238L. The index case at age 10 demonstrated multifocal vitelliform changes that were hyperautofluorescent, cystoid macular edema in the inner nuclear layer, no light rise in the electro-oculography, and a reduced central but preserved peripheral retinal function by multifocal electroretinography. Full-field electroretinography demonstrated a reduced rod response and inner retina dysfunction. Retinal structure was normal in all 3 family members who carried a sequence change in BEST1. Electro-oculography light peak was reduced in both the mother and sister (heterozygous for p.Q238L). Immunohistochemistry could not confirm the presence of Bestrophin in normal human retina. CONCLUSIONS Because of a relatively well preserved retinal function, autosomal recessive bestrophinopathy may be a suitable first candidate, among the BEST1-related ocular conditions, for gene replacement therapy.
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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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Reuter P, Kohl S, Bernd A, Wissinger B. Erbliche Ionenkanalerkrankungen der Netzhaut. MED GENET-BERLIN 2013. [DOI: 10.1007/s11825-013-0422-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Zusammenfassung
Retinale Ionenkanalerkrankungen sind klinisch und genetisch sehr heterogen. Die bisher identifizierten krankheitsassoziierten Ionenkanäle umfassen zyklisch nukleotidgesteuerte (CNG-)Kanäle, spannungsgesteuerte Kalium- und Kalziumkanäle, einen einwärtsrektifizierenden Kaliumkanal, einen kalziumaktivierten Chloridkanal und den transienten Rezeptorpotenzialionenkanal TRPM1. Dieses breite Spektrum spiegelt sich auch in der resultierenden Pathophysiologie wieder. Mutationen in retinalen Ionenkanälen können die Detektion von Lichtreizen bzw. deren Umwandlung in ein elektrisches Signal oder die Weiterleitung des Signals von den Fotorezeptoren zu nachgeschalteten Neuronen beeinträchtigen. Einige Erkrankungen werden auch durch Mutationen in Ionenkanälen, die im retinalen Pigmentepithel lokalisiert sind, hervorgerufen. Dieses ist mit seinen unterstützenden Aufgaben für eine normale Netzhautfunktion essenziell.
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Affiliation(s)
- P. Reuter
- Aff1 grid.411544.1 0000000101968249 Molekulargenetisches Labor Forschungsinstitut für Augenheilkunde, Universitätsklinikum Tübingen Röntgenweg 11 72076 Tübingen Deutschland
| | - S. Kohl
- Aff1 grid.411544.1 0000000101968249 Molekulargenetisches Labor Forschungsinstitut für Augenheilkunde, Universitätsklinikum Tübingen Röntgenweg 11 72076 Tübingen Deutschland
| | - A. Bernd
- Aff2 grid.411544.1 0000000101968249 Universitätsaugenklinik Tübingen Tübingen Deutschland
| | - B. Wissinger
- Aff1 grid.411544.1 0000000101968249 Molekulargenetisches Labor Forschungsinstitut für Augenheilkunde, Universitätsklinikum Tübingen Röntgenweg 11 72076 Tübingen Deutschland
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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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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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