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Saxena H, Weintraub NL, Tang Y. Potential Therapeutic Targets for Hypotension in Duchenne Muscular Dystrophy. Med Hypotheses 2024; 185:111318. [PMID: 38585412 PMCID: PMC10993928 DOI: 10.1016/j.mehy.2024.111318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Duchenne Muscular Dystrophy (DMD) is marked by genetic mutations occurring in the DMD gene, which is widely expressed in the cardiovascular system. In addition to developing cardiomyopathy, patients with DMD have been reported to be susceptible to the development of symptomatic hypotension, although the mechanisms are unclear. Analysis of single-cell RNA sequencing data has identified potassium voltage-gated channel subfamily Q member 5 (KCNQ5) and possibly ryanodine receptor 2 (RyR2) as potential candidate hypotension genes whose expression is significantly upregulated in the vascular smooth muscle cells of DMD mutant mice. We hypothesize that heightened KCNQ5 and RyR2 expression contributes to decreased arterial blood pressure in patients with DMD. Exploring pharmacological approaches to inhibit the KCNQ5 and RyR2 channels holds promise in managing the systemic hypotension observed in individuals with DMD. This avenue of investigation presents new prospects for improving clinical outcomes for these patients.
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Affiliation(s)
- Harshi Saxena
- Vascular Biology Center, Department of Medicine, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, Augusta, GA 30912, USA
| | - Neal L Weintraub
- Vascular Biology Center, Department of Medicine, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, Augusta, GA 30912, USA
| | - Yaoliang Tang
- Vascular Biology Center, Department of Medicine, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, Augusta, GA 30912, USA
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Ignatova I, Frolov R, Nymark S. The retinal pigment epithelium displays electrical excitability and lateral signal spreading. BMC Biol 2023; 21:84. [PMID: 37069561 PMCID: PMC10111697 DOI: 10.1186/s12915-023-01559-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 03/10/2023] [Indexed: 04/19/2023] Open
Abstract
BACKGROUND The non-neuronal retinal pigment epithelium (RPE) functions in intimate association with retinal photoreceptors, performing a multitude of tasks critical for maintaining retinal homeostasis and collaborating with retinal glial cells to provide metabolic support and ionic buffering. Accordingly, the RPE has recently been shown to display dynamic properties mediated by an array of ion channels usually more characteristic of astrocytes and excitable cells. The recent discovery of canonical voltage-activated Na+ channels in the RPE and their importance for phagocytosis of photoreceptor outer segments raises a question about their electrogenic function. Here, we performed a detailed electrophysiological analysis related to the functioning of these channels in human embryonic stem cell (hESC)-derived RPE. RESULTS Our studies examining the electrical properties of the hESC-RPE revealed that its membrane mainly displays passive properties in a broad voltage range, with the exception of depolarization-induced spikes caused by voltage-activated Na+ current (INa). Spike amplitude depended on the availability of INa and spike kinetics on the membrane time constant, and the spikes could be largely suppressed by TTX. Membrane resistance fluctuated rapidly and strongly, repeatedly changing over the course of recordings and causing closely correlated fluctuations in resting membrane potential. In a minority of cells, we found delayed secondary INa-like inward currents characterized by comparatively small amplitudes and slow kinetics, which produced secondary depolarizing spikes. Up to three consecutive delayed inward current waves were detected. These currents could be rapidly and reversibly augmented by applying L-type Ca2+ channel blocker nifedipine to diminish influx of calcium and thus increase gap junctional conductance. CONCLUSIONS This work shows, for the first time, that INa and INa-mediated voltage spikes can spread laterally through gap junctions in the monolayer of cells that are traditionally considered non-excitable. Our findings support a potential role of the RPE that goes beyond giving homeostatic support to the retina.
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Affiliation(s)
- Irina Ignatova
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | | | - Soile Nymark
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
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Quint WH, Tadema KCD, Kokke NCCJ, Meester-Smoor MA, Miller AC, Willemsen R, Klaver CCW, Iglesias AI. Post-GWAS screening of candidate genes for refractive error in mutant zebrafish models. Sci Rep 2023; 13:2017. [PMID: 36737489 PMCID: PMC9898536 DOI: 10.1038/s41598-023-28944-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/27/2023] [Indexed: 02/05/2023] Open
Abstract
Genome-wide association studies (GWAS) have dissected numerous genetic factors underlying refractive errors (RE) such as myopia. Despite significant insights into understanding the genetic architecture of RE, few studies have validated and explored the functional role of candidate genes within these loci. To functionally follow-up on GWAS and characterize the potential role of candidate genes on the development of RE, we prioritized nine genes (TJP2, PDE11A, SHISA6, LAMA2, LRRC4C, KCNQ5, GNB3, RBFOX1, and GRIA4) based on biological and statistical evidence; and used CRISPR/cas9 to generate knock-out zebrafish mutants. These mutant fish were screened for abnormalities in axial length by spectral-domain optical coherence tomography and refractive status by eccentric photorefraction at the juvenile (2 months) and adult (4 months) developmental stage. We found a significantly increased axial length and myopic shift in refractive status in three of our studied mutants, indicating a potential involvement of the human orthologs (LAMA2, LRRC4C, and KCNQ5) in myopia development. Further, in-situ hybridization studies showed that all three genes are expressed throughout the zebrafish retina. Our zebrafish models provide evidence of a functional role of these three genes in refractive error development and offer opportunities to elucidate pathways driving the retina-to-sclera signaling cascade that leads to myopia.
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Affiliation(s)
- Wim H Quint
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Kirke C D Tadema
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Nina C C J Kokke
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Magda A Meester-Smoor
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Adam C Miller
- Institute of Neuroscience, University of Oregon, Eugene, USA
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
| | - Adriana I Iglesias
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands.
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Korkka I, Skottman H, Nymark S. OUP accepted manuscript. Stem Cells Transl Med 2022; 11:753-766. [PMID: 35639962 PMCID: PMC9299513 DOI: 10.1093/stcltm/szac029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 04/09/2022] [Indexed: 11/15/2022] Open
Abstract
Human pluripotent stem cell (hPSC)-derived retinal pigment epithelium (RPE) is extensively used in RPE research, disease modeling, and transplantation therapies. For successful outcomes, a thorough evaluation of their physiological authenticity is a necessity. Essential determinants of this are the different ion channels of the RPE, yet studies evaluating this machinery in hPSC-RPE are scarce. We examined the functionality and localization of potassium (K+) channels in the human embryonic stem cell (hESC)-derived RPE. We observed a heterogeneous pattern of voltage-gated K+ (KV) and inwardly rectifying K+ (Kir) channels. Delayed rectifier currents were recorded from most of the cells, and immunostainings showed the presence of KV1.3 channel. Sustained M-currents were also present in the hESC-RPE, and based on immunostaining, these currents were carried by KCNQ1-KCNQ5 channel types. Some cells expressed transient A-type currents characteristic of native human fetal RPE (hfRPE) and cultured primary RPE and carried by KV1.4 and KV4.2 channels. Of the highly important Kir channels, we found that Kir7.1 is present both at the apical and basolateral membranes of the hESC- and fresh native mouse RPE. Kir currents, however, were recorded only from 14% of the hESC-RPE cells with relatively low amplitudes. Compared to previous studies, our data suggest that in the hESC-RPE, the characteristics of the delayed rectifier and M-currents resemble native adult RPE, while A-type and Kir currents resemble native hfRPE or cultured primary RPE. Overall, the channelome of the RPE is a sensitive indicator of maturity and functionality affecting its therapeutic utility.
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Affiliation(s)
- Iina Korkka
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Heli Skottman
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Soile Nymark
- Corresponding author: Soile Nymark, PhD, Faculty of Medicine and Health Technology, Tampere University, Arvo Ylpön katu 34, 33520 Tampere, Finland. Tel: +358 40 849 0009; E-mail:
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Yang Q, Tan QQ, Lan CJ, Lv BZ, Zhou GM, Zhong WQ, Gu ZM, Mao YM, Liao X. The Changes of KCNQ5 Expression and Potassium Microenvironment in the Retina of Myopic Guinea Pigs. Front Physiol 2021; 12:790580. [PMID: 35002772 PMCID: PMC8733613 DOI: 10.3389/fphys.2021.790580] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
KCNQ5 is suggestively associated with myopia, but its specific role in the myopic process has not been studied further. The aim of this study was to investigate the expression of potassium channel gene KCNQ5 and the changes of K+ microenvironment within the retina of form deprivation myopia (FDM) guinea pigs. A total of 60 guinea pigs were randomly divided into the normal control (NC) group, the self-control (SC) group, and the form-deprivation (FD) group for different treatments. Molecular assays and immunohistochemistry (IHC) were conducted to measure the expression and distribution of KCNQ5-related gene and protein in the retina. We determined the K+ concentration in the retina. In addition, the possible effects of form deprivation on potassium ionic currents and the pharmacological sensitivity of KCNQ5 activator Retigabine and inhibitor XE991 to the M-current in RPE cells were investigated using the patch-clamp technique. As a result, FD eyes exhibited more myopic refraction and longer AL. The mRNA and protein levels of KCNQ5 significantly decreased in the FD eyes, but the K+ concentration increased. In addition, the M-type K+ current [IK(M)] density decreased in FD RPE cells, and were activated or inhibited in a concentration-dependent manner due to the addition of Retigabine or XE991. Overall, KCNQ5 was significantly downregulated in the retina of FD guinea pigs, which may be associated with the increasing K+ concentration, decreasing IK(M) density, and elongating ocular axis. It suggested that KCNQ5 may play a role in the process of myopia, and the intervention of potassium channels may contribute to the prevention and control of myopia.
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Affiliation(s)
- Qin Yang
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
- The Translational Medicine Research Center and the Hepatobiliary Research Institute (North Sichuan Medical College), Nanchong, China
| | - Qing Qing Tan
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
| | - Chang Jun Lan
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
| | - Bo Zhen Lv
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Gui Mei Zhou
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
| | - Wei Qi Zhong
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
- The Translational Medicine Research Center and the Hepatobiliary Research Institute (North Sichuan Medical College), Nanchong, China
| | - Zhi Ming Gu
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
- The Translational Medicine Research Center and the Hepatobiliary Research Institute (North Sichuan Medical College), Nanchong, China
| | - Yu Mei Mao
- The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xuan Liao
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
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Skarphedinsdottir SB, Eysteinsson T, Árnason SS. Mechanisms of Ion Transport Across the Mouse Retinal Pigment Epithelium Measured In Vitro. Invest Ophthalmol Vis Sci 2021; 61:31. [PMID: 32539134 PMCID: PMC7416899 DOI: 10.1167/iovs.61.6.31] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Purpose To examine ion transport across the mouse retinal pigment epithelium (RPE), measured by the short-circuit current (ISC) and transepithelial resistance (TER). Methods Sheets of RPE from mice (C57BL6/J) with retina, choroid, and sclera attached were mounted in Ussing chambers (0.031-cm2 aperture) and Krebs solution. The ISC and TER were recorded with voltage clamps. Receptors implicated in ion transport were blocked or stimulated by ligands applied to both sides. Results The mean initial ISC was −12.0 ± 3.9 µA/cm2 (basolateral negative), and mean TER was 67.1 ± 8.0 ohm·cm2. RPE preparations remained stable for 3 hours, with ISC decreasing by 0.078 ± 0,033 µA/cm2/hr. Adenosine triphosphate (100 µM) increased ISC by 2.22 ± 0.41 µA/cm2 (P = 0.003). Epinephrine (100 µM) increased ISC by 1.14 ± 0.19 µA/cm2 (P = 0.011). Bumetanide (100 µM) reduced ISC by 1.72 ± 0.73 µA/cm2 (P = 0.027). Ouabain (1 mM) induced a biphasic response: an ISC increase from −7.9 ± 2.4 to −15.49 ± 2.12 µA/cm2 and then a decrease to −3.7 ± 2.2 µA/cm2. Ouabain increased TER by 15.3 ± 4.8 ohm·cm2. These compounds were added sequentially. Apical [K+]o at zero mM transiently increased ISC by 3.36 ± 1.06 µA/cm2. Ba++ decreased ISC from −10.4 ± 3.1 to −6.6 ± 1.8 µA/cm2 (P = 0.01). Ba++ reversed the K+-free response, with Isc decreasing further from −5.65 ± 1.24 to −3.37 ± 0.79 µA/cm2 (P = 0.029). Conclusions The ISC and TER can be recorded from the mouse RPE for 3 hours. Adrenergic and purinergic receptors affect murine RPE ion transport. Sodium–potassium adenosine triphosphatase plays a role in net ion transport across mouse RPE, and Na-K-2Cl cotransporter activity partly accounts for transepithelial ion transport. Mimicking light-induced changes, low subretinal [K+]o increases ion transport transiently, dependent on K+ channels.
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Chang WT, Ragazzi E, Liu PY, Wu SN. Effective block by pirfenidone, an antifibrotic pyridone compound (5-methyl-1-phenylpyridin-2[H-1]-one), on hyperpolarization-activated cation current: An additional but distinctive target. Eur J Pharmacol 2020; 882:173237. [PMID: 32525005 PMCID: PMC7276140 DOI: 10.1016/j.ejphar.2020.173237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/26/2020] [Accepted: 05/29/2020] [Indexed: 12/26/2022]
Abstract
Pirfenidone (PFD), a pyridone compound, is well recognized as an antifibrotic agent tailored for the treatment of idiopathic pulmonary fibrosis. Recently, through its anti-inflammatory and anti-oxidant effects, PFD based clinical trial has also been launched for the treatment of coronavirus disease (COVID-19). To what extent this drug can perturb membrane ion currents remains largely unknown. Herein, the exposure to PFD was observed to depress the amplitude of hyperpolarization-activated cation current (Ih) in combination with a considerable slowing in the activation time of the current in pituitary GH3 cells. In the continued presence of ivabradine or zatebradine, subsequent application of PFD decreased Ih amplitude further. The presence of PFD resulted in a leftward shift in Ih activation curve without changes in the gating charge. The addition of this compound also led to a reduction in area of voltage-dependent hysteresis evoked by long-lasting inverted triangular (downsloping and upsloping) ramp pulse. Neither the amplitude of M-type nor erg-mediated K+ current was altered by its presence. In whole-cell potential recordings, addition of PFD reduced the firing frequency, and this effect was accompanied by the depression in the amplitude of sag voltage elicited by hyperpolarizing current stimulus. Overall, this study highlights evidence that PFD is capable of perturbing specific ionic currents, revealing a potential additional impact on functional activities of different excitable cells.
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Affiliation(s)
- Wei-Ting Chang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan; Division of Cardiology, Internal Medicine, Chi-Mei Medical Center, Tainan, 71004, Taiwan; Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan, 71004, Taiwan.
| | - Eugenio Ragazzi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131, Padova, Italy
| | - Ping-Yen Liu
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan; Division of Cardiology, Internal Medicine, College of Medicine, National Cheng Kung University Hospital, Tainan, 70401, Taiwan.
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan, Taiwan; Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan.
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Winkelman BHJ, Howlett MHC, Hölzel MB, Joling C, Fransen KH, Pangeni G, Kamermans S, Sakuta H, Noda M, Simonsz HJ, McCall MA, De Zeeuw CI, Kamermans M. Nystagmus in patients with congenital stationary night blindness (CSNB) originates from synchronously firing retinal ganglion cells. PLoS Biol 2019; 17:e3000174. [PMID: 31513577 PMCID: PMC6741852 DOI: 10.1371/journal.pbio.3000174] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 08/12/2019] [Indexed: 11/19/2022] Open
Abstract
Congenital nystagmus, involuntary oscillating small eye movements, is commonly thought to originate from aberrant interactions between brainstem nuclei and foveal cortical pathways. Here, we investigated whether nystagmus associated with congenital stationary night blindness (CSNB) results from primary deficits in the retina. We found that CSNB patients as well as an animal model (nob mice), both of which lacked functional nyctalopin protein (NYX, nyx) in ON bipolar cells (BCs) at their synapse with photoreceptors, showed oscillating eye movements at a frequency of 4-7 Hz. nob ON direction-selective ganglion cells (DSGCs), which detect global motion and project to the accessory optic system (AOS), oscillated with the same frequency as their eyes. In the dark, individual ganglion cells (GCs) oscillated asynchronously, but their oscillations became synchronized by light stimulation. Likewise, both patient and nob mice oscillating eye movements were only present in the light when contrast was present. Retinal pharmacological and genetic manipulations that blocked nob GC oscillations also eliminated their oscillating eye movements, and retinal pharmacological manipulations that reduced the oscillation frequency of nob GCs also reduced the oscillation frequency of their eye movements. We conclude that, in nob mice, synchronized oscillations of retinal GCs, most likely the ON-DCGCs, cause nystagmus with properties similar to those associated with CSNB in humans. These results show that the nob mouse is the first animal model for a form of congenital nystagmus, paving the way for development of therapeutic strategies.
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Affiliation(s)
- Beerend H. J. Winkelman
- Netherlands Institute for Neuroscience, Amsterdam, the Netherlands
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | | | - Maj-Britt Hölzel
- Netherlands Institute for Neuroscience, Amsterdam, the Netherlands
| | - Coen Joling
- Netherlands Institute for Neuroscience, Amsterdam, the Netherlands
| | - Kathryn H. Fransen
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky, United States of America
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, United States of America
| | - Gobinda Pangeni
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky, United States of America
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, United States of America
| | | | - Hiraki Sakuta
- National Institute for Basic Biology, Okazaki, Japan
| | - Masaharu Noda
- National Institute for Basic Biology, Okazaki, Japan
| | - Huibert J. Simonsz
- Netherlands Institute for Neuroscience, Amsterdam, the Netherlands
- Department of Ophthalmology, Erasmus MC, Rotterdam, the Netherlands
| | - Maureen A. McCall
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky, United States of America
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, United States of America
| | - Chris I. De Zeeuw
- Netherlands Institute for Neuroscience, Amsterdam, the Netherlands
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | - Maarten Kamermans
- Netherlands Institute for Neuroscience, Amsterdam, the Netherlands
- Department of Biomedical Physics, Academic Medical Center, University of Amsterdam, the Netherlands
- * E-mail:
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Restoration of patterned vision with an engineered photoactivatable G protein-coupled receptor. Nat Commun 2017; 8:1862. [PMID: 29192252 PMCID: PMC5709376 DOI: 10.1038/s41467-017-01990-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 10/27/2017] [Indexed: 12/21/2022] Open
Abstract
Retinitis pigmentosa results in blindness due to degeneration of photoreceptors, but spares other retinal cells, leading to the hope that expression of light-activated signaling proteins in the surviving cells could restore vision. We used a retinal G protein-coupled receptor, mGluR2, which we chemically engineered to respond to light. In retinal ganglion cells (RGCs) of blind rd1 mice, photoswitch-charged mGluR2 (“SNAG-mGluR2”) evoked robust OFF responses to light, but not in wild-type retinas, revealing selectivity for RGCs that have lost photoreceptor input. SNAG-mGluR2 enabled animals to discriminate parallel from perpendicular lines and parallel lines at varying spacing. Simultaneous viral delivery of the inhibitory SNAG-mGluR2 and excitatory light-activated ionotropic glutamate receptor LiGluR yielded a distribution of expression ratios, restoration of ON, OFF and ON-OFF light responses and improved visual acuity. Thus, SNAG-mGluR2 restores patterned vision and combinatorial light response diversity provides a new logic for enhanced-acuity retinal prosthetics. To restore sight after retinal degeneration, one approach is to express light-sensitive proteins in remaining cells. Here the authors combine a light-sensitive engineered G protein-coupled receptor and ion channels to restore ON and OFF responses as well as superior visual pattern discrimination.
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Modulation of Ether-à-Go-Go Related Gene (ERG) Current Governs Intrinsic Persistent Activity in Rodent Neocortical Pyramidal Cells. J Neurosci 2017; 38:423-440. [PMID: 29175952 DOI: 10.1523/jneurosci.1774-17.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 10/28/2017] [Accepted: 11/17/2017] [Indexed: 12/21/2022] Open
Abstract
While cholinergic receptor activation has long been known to dramatically enhance the excitability of cortical neurons, the cellular mechanisms responsible for this effect are not well understood. We used intracellular recordings in rat (both sexes) neocortical brain slices to assess the ionic mechanisms supporting persistent firing modes triggered by depolarizing stimuli following cholinergic receptor activation. We found multiple lines of evidence suggesting that a component of the underlying hyperexcitability associated with persistent firing reflects a reduction in the standing (leak) K+ current mediated by Ether-a-go-go-Related Gene (ERG) channels. Three chemically diverse ERG channel blockers (terfenadine, ErgToxin-1, and E-4031) abolished persistent firing and the underlying increase in input resistance in deep pyramidal cells in temporal and prefrontal association neocortex. Calcium accumulation during triggering stimuli appears to attenuate ERG currents, leading to membrane potential depolarization and increased input resistance, two critical elements generating persistent firing. Our results also suggest that ERG current normally governs cortical neuron responses to depolarizing stimuli by opposing prolonged discharges and by enhancing the poststimulus repolarization. The broad expression of ERG channels and the ability of ERG blocks to abolish persistent firing evoked by both synaptic and intracellular step stimuli suggest that modulation of ERG channels may underlie many forms of persistent activity observed in vivoSIGNIFICANCE STATEMENT Persistent activity, where spiking continues beyond the triggering stimulus, is a common phenomenon observed in many types of neurons. Identifying the mechanism underlying this elementary process of memory is a step forward in understanding higher cognitive function including short-term memory. Our results suggest that a reduction in the currents normally mediated by Ether-a-go-go-Related Gene (ERG) K+ channels contributes to persistent firing in neocortical pyramidal cells. ERG currents have been previously studied primarily in the heart; relatively little is known about ERG function in the brain, although mutations in ERG channels have recently been linked to schizophrenia. The present study is among the first to describe its role in neocortex in relation to biophysical correlates of memory function.
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Genetic Association Study of KCNQ5 Polymorphisms with High Myopia. BIOMED RESEARCH INTERNATIONAL 2017; 2017:3024156. [PMID: 28884119 PMCID: PMC5572591 DOI: 10.1155/2017/3024156] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 06/10/2017] [Accepted: 07/17/2017] [Indexed: 02/05/2023]
Abstract
Identification of genetic variations related to high myopia may advance our knowledge of the etiopathogenesis of refractive error. This study investigated the role of potassium channel gene (KCNQ5) polymorphisms in high myopia. We performed a case-control study of 1563 unrelated Han Chinese subjects (809 cases of high myopia and 754 emmetropic controls). Five tag single-nucleotide polymorphisms (SNPs) of KCNQ5 were genotyped, and association testing with high myopia was conducted using logistic regression analysis adjusted for sex and age to give Pasym values, and multiple comparisons were corrected by permutation test to give Pemp values. All five noncoding SNPs were associated with high myopia. The SNP rs7744813, previously shown to be associated with refractive error and myopia in two GWAS, showed an odds ratio of 0.75 (95% CI 0.63-0.90; Pemp = 0.0058) for the minor allele. The top SNP rs9342979 showed an odds ratio of 0.75 (95% CI 0.64-0.89; Pemp = 0.0045) for the minor allele. Both SNPs are located within enhancer histone marks and DNase-hypersensitive sites. Our data support the involvement of KCNQ5 gene polymorphisms in the genetic susceptibility to high myopia and further exploration of KCNQ5 as a risk factor for high myopia.
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Kang SW, Ahn JW, Ahn SC. Inhibition of K + outward currents by linopirdine in the cochlear outer hair cells of circling mice within the first postnatal week. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2017; 21:251-257. [PMID: 28280419 PMCID: PMC5343059 DOI: 10.4196/kjpp.2017.21.2.251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/23/2016] [Accepted: 01/11/2017] [Indexed: 11/26/2022]
Abstract
Inhibition of K+ outward currents by linopirdine in the outer hair cells (OHCs) of circling mice (homozygous (cir/cir) mice), an animal model for human deafness (DFNB6 type), was investigated using a whole cell patch clamp technique. Littermate heterozygous (+/cir) and ICR mice of the same age (postnatal day (P) 0 –P6) were used as controls. Voltage steps from –100 mV to 40 mV elicited small inward currents (–100 mV~–70 mV) and slow rising K+ outward currents (–60 mV ~40 mV) which activated near –50 mV in all OHCs tested. Linopirdine, a known blocker of K+ currents activated at negative potentials (IK,n), did cause inhibition at varying degree (severe, moderate, mild) in K+ outward currents of heterozygous (+/cir) or homozygous (cir/cir) mice OHCs in the concentration range between 1 and 100 µM, while it was apparent only in one ICR mice OHC out of nine OHCs at 100 µM. Although the half inhibition concentrations in heterozygous (+/cir) or homozygous (cir/cir) mice OHCs were close to those reported in IK,n, biophysical and pharmacological properties of K+ outward currents, such as the activation close to –50 mV, small inward currents evoked by hyperpolarizing steps and TEA sensitivity, were not in line with IK,n reported in other tissues. Our results show that the delayed rectifier type K+ outward currents, which are not similar to IK,n with respect to biophysical and pharmacological properties, are inhibited by linopirdine in the developing (P0~P6) homozygous (cir/cir) or heterozygous (+/cir) mice OHCs.
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Affiliation(s)
- Shin Wook Kang
- Department of Physiology, College of Medicine, Dankook University, Cheonan 31116, Korea
| | - Ji Woong Ahn
- Department of Physiology, College of Medicine, Dankook University, Cheonan 31116, Korea
| | - Seung Cheol Ahn
- Department of Physiology, College of Medicine, Dankook University, Cheonan 31116, Korea
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Liao X, Lan C, Liao D, Tian J, Huang X. Exploration and detection of potential regulatory variants in refractive error GWAS. Sci Rep 2016; 6:33090. [PMID: 27604318 PMCID: PMC5015044 DOI: 10.1038/srep33090] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 08/19/2016] [Indexed: 11/19/2022] Open
Abstract
Refractive error (RE) is a complex multifactorial disease. Genome-wide association studies (GWAS) have provided significant insight into the genetic architecture and identified plenty of robust genetic variations or single nucleotide polymorphisms (SNPs) associated with complex disease. A major current challenge is to convert those resources into causal variants and target genes. We used RegulomeDB and HaploReg to annotate regulatory information onto associated SNPs derived from the two largest RE GWAS, and additional SNPs in linkage disequilibrium (LD) with GWAS significant SNPs. Overall 868 SNPs were investigated, out of which 662 returned RegulomeDB scores of 1 to 6. It was observed that 36 out of those SNPs show strong evidence of regulatory effects with a RegulomeDB score of 1, while only four of them were GWAS significant SNPs (CD55/rs1652333, CNDP2/rs12971120, RDH5/rs3138142 and rs3138144). The results encourage us to explore those putative pathogenic variants, both GWAS significant SNPs as well as the SNPs in LD, for future discernment of functional consequence. This study offers the attractive approach for prioritizing potential functional variants by combining ENCODE data and GWAS information, and provide further insights into the pathogenesis and mechanism and ultimately therapeutics.
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Affiliation(s)
- Xuan Liao
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
| | - ChangJun Lan
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
| | - Dan Liao
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
| | - Jing Tian
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
| | - XiuQi Huang
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
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14
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KCNQ potassium channels in sensory system and neural circuits. Acta Pharmacol Sin 2016; 37:25-33. [PMID: 26687932 DOI: 10.1038/aps.2015.131] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/10/2015] [Indexed: 12/15/2022] Open
Abstract
M channels, an important regulator of neural excitability, are composed of four subunits of the Kv7 (KCNQ) K(+) channel family. M channels were named as such because their activity was suppressed by stimulation of muscarinic acetylcholine receptors. These channels are of particular interest because they are activated at the subthreshold membrane potentials. Furthermore, neural KCNQ channels are drug targets for the treatments of epilepsy and a variety of neurological disorders, including chronic and neuropathic pain, deafness, and mental illness. This review will update readers on the roles of KCNQ channels in the sensory system and neural circuits as well as discuss their respective mechanisms and the implications for physiology and medicine. We will also consider future perspectives and the development of additional pharmacological models, such as seizure, stroke, pain and mental illness, which work in combination with drug-design targeting of KCNQ channels. These models will hopefully deepen our understanding of KCNQ channels and provide general therapeutic prospects of related channelopathies.
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15
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Mani BK, Robakowski C, Brueggemann LI, Cribbs LL, Tripathi A, Majetschak M, Byron KL. Kv7.5 Potassium Channel Subunits Are the Primary Targets for PKA-Dependent Enhancement of Vascular Smooth Muscle Kv7 Currents. Mol Pharmacol 2015; 89:323-34. [PMID: 26700561 DOI: 10.1124/mol.115.101758] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 12/18/2015] [Indexed: 12/11/2022] Open
Abstract
Kv7 (KCNQ) channels, formed as homo- or heterotetramers of Kv7.4 and Kv7.5 α-subunits, are important regulators of vascular smooth muscle cell (VSMC) membrane voltage. Recent studies demonstrate that direct pharmacological modulation of VSMC Kv7 channel activity can influence blood vessel contractility and diameter. However, the physiologic regulation of Kv7 channel activity is still poorly understood. Here, we study the effect of cAMP/protein kinase A (PKA) activation on whole cell K(+) currents through endogenous Kv7.5 channels in A7r5 rat aortic smooth muscle cells or through Kv7.4/Kv7.5 heteromeric channels natively expressed in rat mesenteric artery smooth muscle cells. The contributions of specific α-subunits are further dissected using exogenously expressed human Kv7.4 and Kv7.5 homo- or heterotetrameric channels in A7r5 cells. Stimulation of Gαs-coupled β-adrenergic receptors with isoproterenol induced PKA-dependent activation of endogenous Kv7.5 currents in A7r5 cells. The receptor-mediated enhancement of Kv7.5 currents was mimicked by pharmacological agents that increase [cAMP] (forskolin, rolipram, 3-isobutyl-1-methylxanthine, and papaverine) or mimic cAMP (8-bromo-cAMP); the 2- to 4-fold PKA-dependent enhancement of currents was also observed with exogenously expressed Kv7.5 channels. In contrast, exogenously-expressed heterotetrameric Kv7.4/7.5 channels in A7r5 cells or native mesenteric artery smooth muscle Kv7.4/7.5 channels were only modestly enhanced, and homo-tetrameric Kv7.4 channels were insensitive to this regulatory pathway. Correspondingly, proximity ligation assays indicated that isoproterenol induced PKA-dependent phosphorylation of exogenously expressed Kv7.5 channel subunits, but not of Kv7.4 subunits. These results suggest that signal transduction-mediated responsiveness of vascular smooth muscle Kv7 channel subunits to cAMP/PKA activation follows the order of Kv7.5 >> Kv7.4/Kv7.5 > Kv7.4.
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Affiliation(s)
- Bharath K Mani
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Christina Robakowski
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Lyubov I Brueggemann
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Leanne L Cribbs
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Abhishek Tripathi
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Matthias Majetschak
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Kenneth L Byron
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
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16
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Caminos E, Vaquero CF, Martinez-Galan JR. Relationship between rat retinal degeneration and potassium channel KCNQ5 expression. Exp Eye Res 2014; 131:1-11. [PMID: 25499209 DOI: 10.1016/j.exer.2014.12.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/02/2014] [Accepted: 12/09/2014] [Indexed: 11/29/2022]
Abstract
KCNQ5/Kv7.5 is a low-threshold non-inactivating voltage-gated potassium channel preferentially targeted to excitatory endings in brain neurons. The M-type current is mediated by KCNQ5 channel subunits in monkey retinal pigment epithelium cells and in brain neurons. This study was undertaken to analyze KCNQ5 expression and the interaction signals of KCNQ5 with other proteins in normal rat retina and during photoreceptor degeneration. The KCNQ5 expression pattern was studied by immunocytochemistry and Western blot in normal rat retinas (Sprague-Dawley, SD) and P23H-1 rats as a retinitis pigmentosa model. The physical interactions of KCNQ5 with calmodulin (CaM), vesicular glutamate transporter 1 (VGluT1) and glial fibrillary acidic protein (GFAP) were analyzed by in situ proximity ligation assays and were supported by calcium recording. KCNQ5 expression was found in the plexiform layers, ganglion cell layer and basal membrane of the retinal pigment epithelium. The physical interactions among KCNQ5 and CaM, VGluT1 and GFAP changed with age and during retinal degeneration. The maximal level of KCNQ5/CaM interaction was found when photoreceptors had almost completely disappeared; the KCNQ5/VGluT1 interaction signal decreased and the KCNQ5/GFAP interaction increased in the inner retina, while degeneration progressed. The basal calcium levels in the astrocytes and neurons of P23H-1 were higher than in the control SD retinas. This study demonstrates that KCNQ5 is present in the rat retina where its activity may be moderated by CaM. Retinal degeneration progression in P23H-1 rats can be followed by an interaction between KCNQ5 with CaM in an in situ system. The relationship between KCNQ5 and VGluT1 or GFAP needs to be more cautiously interpreted.
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Affiliation(s)
- Elena Caminos
- School of Medicine and Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain.
| | - Cecilia F Vaquero
- School of Medicine and Regional Center for Biomedical Research (CRIB), University of Castilla-La Mancha, Albacete, Spain.
| | - Juan R Martinez-Galan
- School of Medicine and Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain.
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17
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Simpson CL, Wojciechowski R, Oexle K, Murgia F, Portas L, Li X, Verhoeven VJM, Vitart V, Schache M, Hosseini SM, Hysi PG, Raffel LJ, Cotch MF, Chew E, Klein BEK, Klein R, Wong TY, van Duijn CM, Mitchell P, Saw SM, Fossarello M, Wang JJ, Polašek O, Campbell H, Rudan I, Oostra BA, Uitterlinden AG, Hofman A, Rivadeneira F, Amin N, Karssen LC, Vingerling JR, Döring A, Bettecken T, Bencic G, Gieger C, Wichmann HE, Wilson JF, Venturini C, Fleck B, Cumberland PM, Rahi JS, Hammond CJ, Hayward C, Wright AF, Paterson AD, Baird PN, Klaver CCW, Rotter JI, Pirastu M, Meitinger T, Bailey-Wilson JE, Stambolian D. Genome-wide meta-analysis of myopia and hyperopia provides evidence for replication of 11 loci. PLoS One 2014; 9:e107110. [PMID: 25233373 PMCID: PMC4169415 DOI: 10.1371/journal.pone.0107110] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 08/12/2014] [Indexed: 01/01/2023] Open
Abstract
Refractive error (RE) is a complex, multifactorial disorder characterized by a mismatch between the optical power of the eye and its axial length that causes object images to be focused off the retina. The two major subtypes of RE are myopia (nearsightedness) and hyperopia (farsightedness), which represent opposite ends of the distribution of the quantitative measure of spherical refraction. We performed a fixed effects meta-analysis of genome-wide association results of myopia and hyperopia from 9 studies of European-derived populations: AREDS, KORA, FES, OGP-Talana, MESA, RSI, RSII, RSIII and ERF. One genome-wide significant region was observed for myopia, corresponding to a previously identified myopia locus on 8q12 (p = 1.25×10(-8)), which has been reported by Kiefer et al. as significantly associated with myopia age at onset and Verhoeven et al. as significantly associated to mean spherical-equivalent (MSE) refractive error. We observed two genome-wide significant associations with hyperopia. These regions overlapped with loci on 15q14 (minimum p value = 9.11×10(-11)) and 8q12 (minimum p value 1.82×10(-11)) previously reported for MSE and myopia age at onset. We also used an intermarker linkage- disequilibrium-based method for calculating the effective number of tests in targeted regional replication analyses. We analyzed myopia (which represents the closest phenotype in our data to the one used by Kiefer et al.) and showed replication of 10 additional loci associated with myopia previously reported by Kiefer et al. This is the first replication of these loci using myopia as the trait under analysis. "Replication-level" association was also seen between hyperopia and 12 of Kiefer et al.'s published loci. For the loci that show evidence of association to both myopia and hyperopia, the estimated effect of the risk alleles were in opposite directions for the two traits. This suggests that these loci are important contributors to variation of refractive error across the distribution.
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Affiliation(s)
- Claire L. Simpson
- National Human Genome Research Institute, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Robert Wojciechowski
- National Human Genome Research Institute, National Institutes of Health, Baltimore, Maryland, United States of America
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Konrad Oexle
- Institute of Human Genetics, Technische Universität München, Munich, Germany
| | - Federico Murgia
- Institute of Population Genetics, National Research Council of Italy, Sassari, Italy
| | - Laura Portas
- Institute of Population Genetics, National Research Council of Italy, Sassari, Italy
| | - Xiaohui Li
- Institute for Translational Genomics and Population Sciences, Los Angeles BioMedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Virginie J. M. Verhoeven
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Veronique Vitart
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, United Kingdom
| | - Maria Schache
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - S. Mohsen Hosseini
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada, and DCCT/EDIC Research Group, The Diabetes Control and Complications Trial and Follow-up Study, The Biostatistics Center, The George Washington University, Rockville, Maryland, United States of America
| | - Pirro G. Hysi
- Department of Twin Research & Genetic Epidemiology, King's College London, St Thomas' Hospital, London, United Kingdom
| | - Leslie J. Raffel
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Mary Frances Cotch
- Division of Epidemiology and Clinical Applications, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Emily Chew
- Division of Epidemiology and Clinical Applications, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Barbara E. K. Klein
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Ronald Klein
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Tien Yin Wong
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Singapore Eye Research Institute, National University of Singapore, Singapore, Singapore
| | | | - Paul Mitchell
- Centre for Vision Research, Department of Ophthalmology and Westmead Millennium Institute, University of Sydney, Sydney, Australia
| | - Seang Mei Saw
- Department of Epidemiology and Public Health, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Maurizio Fossarello
- Dipartimento di Scienze Chirurgiche, Clinica Oculistica Universita' degli studi di Cagliari, Cagliari, Italy
| | - Jie Jin Wang
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Centre for Vision Research, Department of Ophthalmology and Westmead Millennium Institute, University of Sydney, Sydney, Australia
| | - DCCT/EDIC Research Group
- The Diabetes Control and Complications Trial and Follow-up Study, The Biostatistics Center, The George Washington University, Rockville, Maryland, United States of America
| | - Ozren Polašek
- Croatian Centre for Global Health, University of Split Medical School, Split, Croatia
| | - Harry Campbell
- Centre for Population Health Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Igor Rudan
- Centre for Population Health Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ben A. Oostra
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, the Netherlands
| | - André G. Uitterlinden
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
- Netherlands Consortium for Healthy Ageing, Netherlands Genomics Initiative, The Hague, the Netherlands
| | - Albert Hofman
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
- Netherlands Consortium for Healthy Ageing, Netherlands Genomics Initiative, The Hague, the Netherlands
| | - Fernando Rivadeneira
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
- Netherlands Consortium for Healthy Ageing, Netherlands Genomics Initiative, The Hague, the Netherlands
| | - Najaf Amin
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Lennart C. Karssen
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Johannes R. Vingerling
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Angela Döring
- Institute of Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Thomas Bettecken
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Goran Bencic
- Department of Ophthalmology, Hospital “Sestre Milosrdnice”, Zagreb, Croatia
| | - Christian Gieger
- Institute of Genetic Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
| | - H.-Erich Wichmann
- Institute of Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
| | - James F. Wilson
- Centre for Population Health Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Cristina Venturini
- Department of Twin Research & Genetic Epidemiology, King's College London, St Thomas' Hospital, London, United Kingdom
| | - Brian Fleck
- Princess Alexandra Eye Pavilion, Edinburgh, United Kingdom
| | - Phillippa M. Cumberland
- MRC Centre of Epidemiology for Child Health, Institute of Child Health, University College London, London, United Kingdom
| | - Jugnoo S. Rahi
- MRC Centre of Epidemiology for Child Health, Institute of Child Health, University College London, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
- Ulverscroft Vision Research Group, Institute of Child Health, University College London, London, United Kingdom
| | - Chris J. Hammond
- Department of Twin Research & Genetic Epidemiology, King's College London, St Thomas' Hospital, London, United Kingdom
| | - Caroline Hayward
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, United Kingdom
| | - Alan F. Wright
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew D. Paterson
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada, and DCCT/EDIC Research Group, The Diabetes Control and Complications Trial and Follow-up Study, The Biostatistics Center, The George Washington University, Rockville, Maryland, United States of America
| | - Paul N. Baird
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Caroline C. W. Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Jerome I. Rotter
- Institute for Translational Genomics and Population Sciences, Los Angeles BioMedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Mario Pirastu
- Institute of Population Genetics, National Research Council of Italy, Sassari, Italy
| | - Thomas Meitinger
- Institute of Human Genetics, Technische Universität München, Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Joan E. Bailey-Wilson
- National Human Genome Research Institute, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Dwight Stambolian
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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18
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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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19
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Horwitz GC, Risner-Janiczek JR, Holt JR. Mechanotransduction and hyperpolarization-activated currents contribute to spontaneous activity in mouse vestibular ganglion neurons. J Gen Physiol 2014; 143:481-97. [PMID: 24638995 PMCID: PMC3971655 DOI: 10.1085/jgp.201311126] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 02/12/2014] [Indexed: 11/20/2022] Open
Abstract
The hyperpolarization-activated, cyclic nucleotide-sensitive current, Ih, is present in vestibular hair cells and vestibular ganglion neurons, and is required for normal balance function. We sought to identify the molecular correlates and functional relevance of Ih in vestibular ganglion neurons. Ih is carried by channels consisting of homo- or heteromeric assemblies of four protein subunits from the Hcn gene family. The relative expression of Hcn1-4 mRNA was examined using a quantitative reverse transcription PCR (RT-PCR) screen. Hcn2 was the most highly expressed subunit in vestibular neuron cell bodies. Immunolocalization of HCN2 revealed robust expression in cell bodies of all vestibular ganglion neurons. To characterize Ih in vestibular neuron cell bodies and at hair cell-afferent synapses, we developed an intact, ex vivo preparation. We found robust physiological expression of Ih in 89% of cell bodies and 100% of calyx terminals. Ih was significantly larger in calyx terminals than in cell bodies; however, other biophysical characteristics were similar. Ih was absent in calyces lacking Hcn1 and Hcn2, but small Ih was still present in cell bodies, which suggests expression of an additional subunit, perhaps Hcn4. To determine the contributions of hair cell mechanotransduction and Ih to the firing patterns of calyx terminals, we recorded action potentials in current-clamp mode. Mechanotransduction currents were modulated by hair bundle defection and application of calcium chelators to disrupt tip links. Ih activity was modulated using ZD7288 and cAMP. We found that both hair cell transduction and Ih contribute to the rate and regularity of spontaneous action potentials in the vestibular afferent neurons. We propose that modulation of Ih in vestibular ganglion neurons may provide a mechanism for modulation of spontaneous activity in the vestibular periphery.
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Affiliation(s)
- Geoffrey C. Horwitz
- Department of Otolaryngology and F.M. Kirby Neurobiology Center, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115
- Department of Neuroscience and Otolaryngology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Jessica R. Risner-Janiczek
- Department of Neuroscience and Otolaryngology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Jeffrey R. Holt
- Department of Otolaryngology and F.M. Kirby Neurobiology Center, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115
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20
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Zhang X, Hughes BA. KCNQ and KCNE potassium channel subunit expression in bovine retinal pigment epithelium. Exp Eye Res 2013. [DOI: 10.1016/j.exer.2013.10.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Zhang X, Hughes BA. KCNQ and KCNE potassium channel subunit expression in bovine retinal pigment epithelium. Exp Eye Res 2013; 116:424-432. [PMID: 24416770 PMCID: PMC3934573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Human, monkey, and bovine retinal pigment epithelial (RPE) cells exhibit an M-type K+ current, which in many other cell types is mediated by channels composed of KCNQ α-subunits and KCNE auxiliary subunits. Recently, we demonstrated the expression of KCNQ1, KCNQ4, and KCNQ5 in the monkey RPE. Here, we investigated the expression of KCNQ and KCNE subunits in native bovine RPE. RT-PCR analysis revealed the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in the RPE, but, in Western blot analysis of RPE plasma membranes, only KCNQ5 was detected. Among the five members of the KCNE gene family, transcripts for KCNE1, KCNE2, KCNE3, and KCNE4 were detected in bovine RPE, but only KCNE1 and KCNE2 proteins were detected. Immunohistochemistry of frozen bovine retinal sections revealed KCNE1 expression near the apical and basal membranes of the RPE, in cone outer segments, in the outer nuclear layer, and throughout the inner retina. The localization of KCNE1 in the RPE basal membrane, where KCNQ5 was previously found to be present, suggests that this β-subunit may contribute to M-type K(+) channels in this membrane.
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Affiliation(s)
- Xiaoming Zhang
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
| | - Bret A. Hughes
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
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22
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Splinter MY. Efficacy of retigabine in adjunctive treatment of partial onset seizures in adults. J Cent Nerv Syst Dis 2013; 5:31-41. [PMID: 24250245 PMCID: PMC3825677 DOI: 10.4137/jcnsd.s9299] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Objective To evaluate efficacy and tolerability of retigabine (ezogabine, US adopted name) in the adjunctive treatment of partial-onset seizures in adults. Retigabine is the first anticonvulsant in its class, decreasing neuronal excitability by opening voltage-gated potassium channels. Methods MEDLINE and EMBASE were systematically searched using search terms retigabine and ezogabine for randomized controlled trials published from 1980 through August 17, 2013. Additionally, articles relating to pharmacology, pharmacokinetics, tolerability and interactions were examined for inclusion. Published abstracts and websites of the Food and Drug Administration and European Medication Agency were reviewed for additional relevant information. Results One phase IIb and two phase III trials were identified. Retigabine has been reported to have dose dependent efficacy in adjunctive treatment of resistant partial-onset seizures in adults in doses of 600, 900 and 1200 mg/day. Similar to other anticonvulsants, the most common adverse events were central nervous system related. Retigabine has several unique adverse events compared to other anticonvulsants: urinary retention and, with extended use, pigment changes to the skin and retina. Retigabine is metabolized by glucuronidation and acetylation. There are few drug interactions with retigabine. Conclusions Retigabine has been shown to have efficacy when used as adjunctive therapy in partial-onset seizures. It has a novel mechanism of action, activation of voltage-gated potassium channels. It has less drug interactions than many other anticonvulsants because it is not metabolized through the P-450 system. Its place in therapy has yet to be determined, especially with recent reports of pigment discoloration of skin and the retina with extended use.
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Affiliation(s)
- Michele Y Splinter
- University of Oklahoma Health Sciences Center, College of Pharmacy, Department of Pharmacy: Clinical and Administrative Sciences, Oklahoma City, OK
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23
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Jankovic S, Ilickovic I. The preclinical discovery and development of ezogabine for the treatment of epilepsy. Expert Opin Drug Discov 2013; 8:1429-37. [DOI: 10.1517/17460441.2013.837882] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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24
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Verhoeven VJM, Hysi PG, Wojciechowski R, Fan Q, Guggenheim JA, Höhn R, MacGregor S, Hewitt AW, Nag A, Cheng CY, Yonova-Doing E, Zhou X, Ikram MK, Buitendijk GHS, McMahon G, Kemp JP, Pourcain BS, Simpson CL, Mäkelä KM, Lehtimäki T, Kähönen M, Paterson AD, Hosseini SM, Wong HS, Xu L, Jonas JB, Pärssinen O, Wedenoja J, Yip SP, Ho DWH, Pang CP, Chen LJ, Burdon KP, Craig JE, Klein BEK, Klein R, Haller T, Metspalu A, Khor CC, Tai ES, Aung T, Vithana E, Tay WT, Barathi VA, Chen P, Li R, Liao J, Zheng Y, Ong RT, Döring A, Evans DM, Timpson NJ, Verkerk AJMH, Meitinger T, Raitakari O, Hawthorne F, Spector TD, Karssen LC, Pirastu M, Murgia F, Ang W, Mishra A, Montgomery GW, Pennell CE, Cumberland PM, Cotlarciuc I, Mitchell P, Wang JJ, Schache M, Janmahasatian S, Janmahasathian S, Igo RP, Lass JH, Chew E, Iyengar SK, Gorgels TGMF, Rudan I, Hayward C, Wright AF, Polasek O, Vatavuk Z, Wilson JF, Fleck B, Zeller T, Mirshahi A, Müller C, Uitterlinden AG, Rivadeneira F, Vingerling JR, Hofman A, Oostra BA, Amin N, Bergen AAB, Teo YY, Rahi JS, Vitart V, Williams C, Baird PN, Wong TY, Oexle K, Pfeiffer N, Mackey DA, Young TL, van Duijn CM, Saw SM, Bailey-Wilson JE, Stambolian D, Klaver CC, Hammond CJ. Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia. Nat Genet 2013; 45:314-8. [PMID: 23396134 PMCID: PMC3740568 DOI: 10.1038/ng.2554] [Citation(s) in RCA: 337] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 01/16/2013] [Indexed: 02/06/2023]
Abstract
Refractive error is the most common eye disorder worldwide and is a prominent cause of blindness. Myopia affects over 30% of Western populations and up to 80% of Asians. The CREAM consortium conducted genome-wide meta-analyses, including 37,382 individuals from 27 studies of European ancestry and 8,376 from 5 Asian cohorts. We identified 16 new loci for refractive error in individuals of European ancestry, of which 8 were shared with Asians. Combined analysis identified 8 additional associated loci. The new loci include candidate genes with functions in neurotransmission (GRIA4), ion transport (KCNQ5), retinoic acid metabolism (RDH5), extracellular matrix remodeling (LAMA2 and BMP2) and eye development (SIX6 and PRSS56). We also confirmed previously reported associations with GJD2 and RASGRF1. Risk score analysis using associated SNPs showed a tenfold increased risk of myopia for individuals carrying the highest genetic load. Our results, based on a large meta-analysis across independent multiancestry studies, considerably advance understanding of the mechanisms involved in refractive error and myopia.
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25
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Kiefer AK, Tung JY, Do CB, Hinds DA, Mountain JL, Francke U, Eriksson N. Genome-wide analysis points to roles for extracellular matrix remodeling, the visual cycle, and neuronal development in myopia. PLoS Genet 2013; 9:e1003299. [PMID: 23468642 PMCID: PMC3585144 DOI: 10.1371/journal.pgen.1003299] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 12/18/2012] [Indexed: 11/18/2022] Open
Abstract
Myopia, or nearsightedness, is the most common eye disorder, resulting primarily from excess elongation of the eye. The etiology of myopia, although known to be complex, is poorly understood. Here we report the largest ever genome-wide association study (45,771 participants) on myopia in Europeans. We performed a survival analysis on age of myopia onset and identified 22 significant associations (), two of which are replications of earlier associations with refractive error. Ten of the 20 novel associations identified replicate in a separate cohort of 8,323 participants who reported if they had developed myopia before age 10. These 22 associations in total explain 2.9% of the variance in myopia age of onset and point toward a number of different mechanisms behind the development of myopia. One association is in the gene PRSS56, which has previously been linked to abnormally small eyes; one is in a gene that forms part of the extracellular matrix (LAMA2); two are in or near genes involved in the regeneration of 11-cis-retinal (RGR and RDH5); two are near genes known to be involved in the growth and guidance of retinal ganglion cells (ZIC2, SFRP1); and five are in or near genes involved in neuronal signaling or development. These novel findings point toward multiple genetic factors involved in the development of myopia and suggest that complex interactions between extracellular matrix remodeling, neuronal development, and visual signals from the retina may underlie the development of myopia in humans. The genetic basis of myopia, or nearsightedness, is believed to be complex and affected by multiple genes. Two genetic association studies have each identified a single genetic region associated with myopia in European populations. Here we report the results of the largest ever genetic association study on myopia in over 45,000 people of European ancestry. We identified 22 genetic regions significantly associated with myopia age of onset. Two are replications of the previously identified associations, and 20 are novel. Ten of the novel associations replicate in a small separate cohort. Sixteen of the novel associations are in or near genes implicated in eye development, neuronal development and signaling, the visual cycle of the retina, and general morphology: BMP3, BMP4, DLG2, DLX1, KCNMA1, KCNQ5, LAMA2, LRRC4C, PRSS56, RBFOX1, RDH5, RGR, SFRP1, TJP2, ZBTB38, and ZIC2. These findings point to numerous biological pathways involved in the development of myopia and, in particular, suggest that early eye and neuronal development may lead to the eventual development of myopia in humans.
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Affiliation(s)
- Amy K. Kiefer
- 23andMe, Mountain View, California, United States of America
| | - Joyce Y. Tung
- 23andMe, Mountain View, California, United States of America
| | - Chuong B. Do
- 23andMe, Mountain View, California, United States of America
| | - David A. Hinds
- 23andMe, Mountain View, California, United States of America
| | | | - Uta Francke
- 23andMe, Mountain View, California, United States of America
| | - Nicholas Eriksson
- 23andMe, Mountain View, California, United States of America
- * E-mail:
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