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Melnyk S, Bollag WB. Aquaporins in the Cornea. Int J Mol Sci 2024; 25:3748. [PMID: 38612559 PMCID: PMC11011575 DOI: 10.3390/ijms25073748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/18/2024] [Accepted: 03/21/2024] [Indexed: 04/14/2024] Open
Abstract
The cornea is an avascular, transparent tissue that allows light to enter the visual system. Accurate vision requires proper maintenance of the cornea's integrity and structure. Due to its exposure to the external environment, the cornea is prone to injury and must undergo proper wound healing to restore vision. Aquaporins (AQPs) are a family of water channels important for passive water transport and, in some family members, the transport of other small molecules; AQPs are expressed in all layers of the cornea. Although their functions as water channels are well established, the direct function of AQPs in the cornea is still being determined and is the focus of this review. AQPs, primarily AQP1, AQP3, and AQP5, have been found to play an important role in maintaining water homeostasis, the corneal structure in relation to proper hydration, and stress responses, as well as wound healing in all layers of the cornea. Due to their many functions in the cornea, the identification of drug targets that modulate the expression of AQPs in the cornea could be beneficial to promote corneal wound healing and restore proper function of this tissue crucial for vision.
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Affiliation(s)
- Samuel Melnyk
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
| | - Wendy B. Bollag
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
- Charlie Norwood Department of Veterans Affairs Medical Center, Augusta, GA 30904, USA
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Chung DD, Chen AC, Choo CH, Zhang W, Williams D, Griffis CG, Bonezzi P, Jatavallabhula K, Sampath AP, Aldave AJ. Investigation of the functional impact of CHED- and FECD4-associated SLC4A11 mutations in human corneal endothelial cells. PLoS One 2024; 19:e0296928. [PMID: 38252645 PMCID: PMC10802951 DOI: 10.1371/journal.pone.0296928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 12/22/2023] [Indexed: 01/24/2024] Open
Abstract
Mutations in the solute linked carrier family 4 member 11 (SLC4A11) gene are associated with congenital hereditary endothelial dystrophy (CHED) and Fuchs corneal endothelial dystrophy type 4 (FECD4), both characterized by corneal endothelial cell (CEnC) dysfunction and/or cell loss leading to corneal edema and visual impairment. In this study, we characterize the impact of CHED-/FECD4-associated SLC4A11 mutations on CEnC function and SLC4A11 protein localization by generating and comparing human CEnC (hCEnC) lines expressing wild type SLC4A11 (SLC4A11WT) or mutant SLC4A11 harboring CHED-/FECD4-associated SLC4A11 mutations (SLC4A11MU). SLC4A11WT and SLC4A11MU hCEnC lines were generated to express either SLC4A11 variant 2 (V2WT and V2MU) or variant 3 (V3WT and V3MU), the two major variants expressed in ex vivo hCEnC. Functional assays were performed to assess cell barrier, proliferation, viability, migration, and NH3-induced membrane conductance. We demonstrate SLC4A11-/- and SLC4A11MU hCEnC lines exhibited increased migration rates, altered proliferation and decreased cell viability compared to SLC4A11WT hCEnC. Additionally, SLC4A11-/- hCEnC demonstrated decreased cell-substrate adhesion and membrane capacitances compared to SLC4A11WT hCEnC. Induction with 10mM NH4Cl led SLC4A11WT hCEnC to depolarize; conversely, SLC4A11-/- hCEnC hyperpolarized and the majority of SLC4A11MU hCEnC either hyperpolarized or had minimal membrane potential changes following NH4Cl induction. Immunostaining of primary hCEnC and SLC4A11WT hCEnC lines for SLC4A11 demonstrated predominately plasma membrane staining with poor or partial colocalization with mitochondrial marker COX4 within a subset of punctate subcellular structures. Overall, our findings suggest CHED-associated SLC4A11 mutations likely lead to hCEnC dysfunction, and ultimately CHED, by interfering with cell migration, proliferation, viability, membrane conductance, barrier function, and/or cell surface localization of the SLC4A11 protein in hCEnC. Additionally, based on their similar subcellular localization and exhibiting similar cell functional profiles, protein isoforms encoded by SLC4A11 variant 2 and variant 3 likely have highly overlapping functional roles in hCEnC.
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Affiliation(s)
- Doug D. Chung
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
| | - Angela C. Chen
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
| | - Charlene H. Choo
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
| | - Wenlin Zhang
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
| | - Dominic Williams
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
| | - Christopher G. Griffis
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
| | - Paul Bonezzi
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
| | - Kavya Jatavallabhula
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
| | - Alapakkam P. Sampath
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
| | - Anthony J. Aldave
- Department of Ophthalmology, Stein Eye Institute at UCLA, Los Angeles, California, United States of America
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Zhen T, Li Y, Guo Q, Yao S, You Y, Lei B. Pathogenicity and Function Analysis of Two Novel SLC4A11 Variants in Patients With Congenital Hereditary Endothelial Dystrophy. Transl Vis Sci Technol 2023; 12:1. [PMID: 37787991 PMCID: PMC10561774 DOI: 10.1167/tvst.12.10.1] [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] [Received: 04/12/2023] [Accepted: 08/10/2023] [Indexed: 10/04/2023] Open
Abstract
Purpose The purpose of this study was to explore the pathogenicity and function of two novel SLC4A11 variants associated with congenital hereditary endothelial dystrophy (CHED) and to study the function of a SLC4A11 (K263R) mutant in vitro. Methods Ophthalmic examinations were performed on a 28-year-old male proband with CHED. Whole-exome and Sanger sequencing were applied for mutation screening. Bioinformatics and pathogenicity analysis were performed. HEK293T cells were transfected with the plasmids of empty vector, wild-type SLC4A11, and SLC4A11 (K263R) mutant. The transfected cells were treated with SkQ1. Oxygen consumption, cellular reactive oxygen species (ROS) level, mitochondrial membrane potential, and apoptosis rate were measured. Results The proband had poor visual acuity with nystagmus since childhood. Corneal foggy opacity was evident in both eyes. Two novel SLC4A11 variants were detected. Sanger sequencing showed that the proband's father and sister carried c.1464-1G>T variant, and the proband's mother and sister carried c.788A>G (p.Lys263Arg) variant. Based on the American College of Medical Genetics (ACMG) guidelines, SLC4A11 c.1464-1G>T was pathogenic, whereas c.788A>G, p.K263R was a variant of undetermined significance. In vitro, SLC4A11 (K263R) variant increased ROS level and apoptosis rate. Decrease in mitochondrial membrane potential and oxygen consumption rate were remarkable. Furthermore, SkQ1 decreased ROS levels and apoptosis rate but increased mitochondrial membrane potential in the transfected cells. Conclusions Two novel heterozygous pathogenic variants of the SLC4A11 gene were identified in a family with CHED. The missense variant SLC4A11 (K263R) caused mitochondrial dysfunction and increased apoptosis in mutant transfected cells. In addition, SkQ1 presented a protective effect suggesting the anti-oxidant might be a novel therapeutic drug. Translational Relevance This study verified the pathogenicity of 2 novel variants in the SLC4A11 gene in a CHED family and found an anti-oxidant might be a new drug.
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Affiliation(s)
- Tianjiao Zhen
- Henan University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China
| | - Ya Li
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Qingge Guo
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Shun Yao
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Ya You
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Bo Lei
- Henan University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China
- Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute/Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
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Lu Y, Zuo P, Chen H, Shan H, Wang W, Dai Z, Xu H, Chen Y, Liang L, Ding D, Jin Y, Yin Y. Structural insights into the conformational changes of BTR1/SLC4A11 in complex with PIP 2. Nat Commun 2023; 14:6157. [PMID: 37788993 PMCID: PMC10547724 DOI: 10.1038/s41467-023-41924-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 09/25/2023] [Indexed: 10/05/2023] Open
Abstract
BTR1 (SLC4A11) is a NH3 stimulated H+ (OH-) transporter belonging to the SLC4 family. Dysfunction of BTR1 leads to diseases such as congenital hereditary endothelial dystrophy (CHED) and Fuchs endothelial corneal dystrophy (FECD). However, the mechanistic basis of BTR1 activation by alkaline pH, transport activity regulation and pathogenic mutations remains elusive. Here, we present cryo-EM structures of human BTR1 in the outward-facing state in complex with its activating ligands PIP2 and the inward-facing state with the pathogenic R125H mutation. We reveal that PIP2 binds at the interface between the transmembrane domain and the N-terminal cytosolic domain of BTR1. Disruption of either the PIP2 binding site or protonation of PIP2 phosphate groups by acidic pH can transform BTR1 into an inward-facing conformation. Our results provide insights into the mechanisms of how the transport activity and conformation changes of BTR1 are regulated by PIP2 binding and interaction of TMD and NTD.
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Affiliation(s)
- Yishuo Lu
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Peng Zuo
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Hongyi Chen
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Hui Shan
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China
| | - Weize Wang
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Zonglin Dai
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | | | | | - Ling Liang
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
- Department of Biochemistry and Biophysics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Dian Ding
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Yan Jin
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Yuxin Yin
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China.
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China.
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China.
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Mehta N, Verma A, Achanta DS, Kannabiran C, Roy S, Mishra DK, Chaurasia S, Edward DP, Ramappa M. Updates on congenital hereditary endothelial dystrophy. Taiwan J Ophthalmol 2023; 13:405-416. [PMID: 38249503 PMCID: PMC10798399 DOI: 10.4103/tjo.tjo-d-23-00135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/08/2023] [Accepted: 10/09/2023] [Indexed: 01/23/2024] Open
Abstract
Congenital hereditary endothelial dystrophy (CHED) is a rare genetic corneal disorder causing progressive cornea clouding and significant visual impairment. CHED remains a leading indication for pediatric corneal transplantation despite its infrequency, particularly in regions with high consanguinity rates like Southeast Asia. Identifying the Solute Carrier Family 4 Member 11 (SLC4A11) gene as the genetic basis of CHED has led to the discovery of it's various genetic variations. However, a comprehensive understanding of its clinical-genetic correlation, pathophysiology, and optimal management is ongoing. This review aims to consolidate current knowledge about CHED, covering its genetic origins, pathophysiological mechanisms, clinical presentation, and management strategies. Surgical intervention, such as penetrating keratoplasty (PK), Descemet stripping automated endothelial keratoplasty (DSAEK), and Descemet membrane endothelial keratoplasty (DMEK), remains the primary treatment. DSAEK and DMEK offer advantages over PK, including quicker visual recovery, reduced complications, and longer graft survival, especially in the pediatric age group. The timing of surgical interventions depends on disease severity, age at presentation, comorbidities, and visual potential. Elevated oxidative stress in CHED corneal tissue suggests potential benefits from anti-inflammatory drugs to rescue mutated endothelial cells. Considering the limitations of corneal graft surgeries, exploring novel gene-based molecular therapies are essential for future management. Early diagnosis, appropriate surgical interventions, amblyopia control, and genetic counseling for predictive analysis are pivotal for optimizing CHED management. A multidisciplinary approach involving ophthalmologists, researchers, and genetic counselors is essential for precise diagnosis and optimal care for CHED patients.
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Affiliation(s)
- Neet Mehta
- Academy of Eye Care Education, L V Prasad Eye Institute, Hyderabad, Telangana, India
| | - Anshuman Verma
- Centre for Rare Eye Diseases and Ophthalmic Genetics, L V Prasad Eye Institute, Hyderabad, Telangana, India
- Prof. Brien Holden Eye Research Center, LV Prasad Eye Institute, Hyderabad, Telangana, India
| | - Divya Sree Achanta
- Centre for Rare Eye Diseases and Ophthalmic Genetics, L V Prasad Eye Institute, Hyderabad, Telangana, India
- The Cornea Institute, L V Prasad Eye Institute, Hyderabad, Telangana, India
- Jasti V Ramanamma Children’s Eye Care Center, L V Prasad Eye Institute, Hyderabad, Telangana, India
| | - Chitra Kannabiran
- Prof. Brien Holden Eye Research Center, LV Prasad Eye Institute, Hyderabad, Telangana, India
| | - Sanhita Roy
- Prof. Brien Holden Eye Research Center, LV Prasad Eye Institute, Hyderabad, Telangana, India
| | - Dilip Kumar Mishra
- Ophthalmic Pathology Services, L V Prasad Eye Institute, Hyderabad, Telangana, India
| | - Sunita Chaurasia
- The Cornea Institute, L V Prasad Eye Institute, Hyderabad, Telangana, India
| | - Deepak Paul Edward
- Department of Ophthalmology and Visual Sciences and Pathology, University of Illinois College of Medicine, Chicago, IL, USA
| | - Muralidhar Ramappa
- Centre for Rare Eye Diseases and Ophthalmic Genetics, L V Prasad Eye Institute, Hyderabad, Telangana, India
- The Cornea Institute, L V Prasad Eye Institute, Hyderabad, Telangana, India
- Jasti V Ramanamma Children’s Eye Care Center, L V Prasad Eye Institute, Hyderabad, Telangana, India
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Tsedilina TR, Sharova E, Iakovets V, Skorodumova LO. Systematic review of SLC4A11, ZEB1, LOXHD1, and AGBL1 variants in the development of Fuchs' endothelial corneal dystrophy. Front Med (Lausanne) 2023; 10:1153122. [PMID: 37441688 PMCID: PMC10333596 DOI: 10.3389/fmed.2023.1153122] [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: 01/28/2023] [Accepted: 03/30/2023] [Indexed: 07/15/2023] Open
Abstract
Introduction The pathogenic role of variants in TCF4 and COL8A2 in causing Fuchs' endothelial corneal dystrophy (FECD) is not controversial and has been confirmed by numerous studies. The causal role of other genes, SLC4A11, ZEB1, LOXHD1, and AGBL1, which have been reported to be associated with FECD, is more complicated and less obvious. We performed a systematic review of the variants in the above-mentioned genes in FECD cases, taking into account the currently available population frequency information, transcriptomic data, and the results of functional studies to assess their pathogenicity. Methods Search for articles published in 2005-2022 was performed manually between July 2022 and February 2023. We searched for original research articles in peer-reviewed journals, written in English. Variants in the genes of interest identified in patients with FECD were extracted for the analysis. We classified each presented variant by pathogenicity status according to the ACMG criteria implemented in the Varsome tool. Diagnosis, segregation data, presence of affected relatives, functional analysis results, and gene expression in the corneal endothelium were taken into account. Data on the expression of genes of interest in the corneal endothelium were extracted from articles in which transcriptome analysis was performed. The identification of at least one variant in a gene classified as pathogenic or significantly associated with FECD was required to confirm the causal role of the gene in FECD. Results The analysis included 34 articles with 102 unique ZEB1 variants, 20 articles with 64 SLC4A11 variants, six articles with 26 LOXHD1 variants, and five articles with four AGBL1 variants. Pathogenic status was confirmed for seven SLC4A11 variants found in FECD. No variants in ZEB1, LOXHD1, and AGBL1 genes were classified as pathogenic for FECD. According to the transcriptome data, AGBL1 and LOXHD1 were not expressed in the corneal endothelium. Functional evidence for the association of LOXHD1, and AGBL1 with FECD was conflicting. Conclusion Our analysis confirmed the causal role of SLC4A11 variants in the development of FECD. The causal role of ZEB1, LOXHD1, and AGBL1 variants in FECD has not been confirmed. Further evidence from familial cases and functional analysis is needed to confirm their causal roles in FECD.
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Affiliation(s)
- Tatiana Romanovna Tsedilina
- Laboratory of Human Molecular Genetics, Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia
| | - Elena Sharova
- Laboratory of Human Molecular Genetics, Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia
| | - Valeriia Iakovets
- Laboratory of Human Molecular Genetics, Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia
- I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Liubov Olegovna Skorodumova
- Laboratory of Human Molecular Genetics, Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia
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Ri CC, Mf CR, D RV, T PC, F TC, Ir S, A AG, Ma SU. Boron-Containing Compounds for Prevention, Diagnosis, and Treatment of Human Metabolic Disorders. Biol Trace Elem Res 2023; 201:2222-2239. [PMID: 35771339 DOI: 10.1007/s12011-022-03346-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 06/24/2022] [Indexed: 11/02/2022]
Abstract
The application of natural and synthetic boron-containing compounds (BCC) in biomedical field is expanding. BCC have effects in the metabolism of living organisms. Some boron-enriched supplements are marketed as they exert effects in the bone and skeletal muscle; but also, BCC are being reported as acting on the enzymes and transporters of membrane suggesting they could modify the carbohydrate metabolism linked to some pathologies of high global burden, as an example is diabetes mellitus. Also, some recent findings are showing effects of BCC on lipid metabolism. In this review, information regarding the effects and interaction of these compounds was compiled, as well as the potential application for treating human metabolic disorders is suggested.
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Affiliation(s)
- Córdova-Chávez Ri
- Academia de Fisiología Y Sección de Estudios de Posgrado E Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis Y Díaz Mirón S/N, 11340, Mexico City, Mexico
| | - Carrasco-Ruiz Mf
- Academia de Fisiología Y Sección de Estudios de Posgrado E Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis Y Díaz Mirón S/N, 11340, Mexico City, Mexico
| | - Rodríguez-Vera D
- Academia de Fisiología Y Sección de Estudios de Posgrado E Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis Y Díaz Mirón S/N, 11340, Mexico City, Mexico
| | - Pérez-Capistran T
- Academia de Fisiología Y Sección de Estudios de Posgrado E Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis Y Díaz Mirón S/N, 11340, Mexico City, Mexico
| | - Tamay-Cach F
- Academia de Bioquímica Médica Y Sección de Estudios de Posgrado E Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis Y Díaz Mirón S/N, 11340, Mexico City, Mexico
| | - Scorei Ir
- BioBoron Research Institute, Dunarii 31B Street, 207465, Podari, Romania
| | - Abad-García A
- Academia de Fisiología Y Sección de Estudios de Posgrado E Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis Y Díaz Mirón S/N, 11340, Mexico City, Mexico.
| | - Soriano-Ursúa Ma
- Academia de Fisiología Y Sección de Estudios de Posgrado E Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis Y Díaz Mirón S/N, 11340, Mexico City, Mexico.
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Jalilian I, Muppala S, Ali M, Anderson JD, Phinney B, Salemi M, Wilmarth PA, Murphy CJ, Thomasy SM, Raghunathan V. Cell derived matrices from bovine corneal endothelial cells as a model to study cellular dysfunction. Exp Eye Res 2023; 226:109303. [PMID: 36343671 DOI: 10.1016/j.exer.2022.109303] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 10/12/2022] [Accepted: 10/30/2022] [Indexed: 11/06/2022]
Abstract
PURPOSE Fuchs endothelial corneal dystrophy (FECD) is a progressive corneal disease that impacts the structure and stiffness of the Descemet's membrane (DM), the substratum for corneal endothelial cells (CECs). These structural alterations of the DM could contribute to the loss of the CECs resulting in corneal edema and blindness. Oxidative stress and transforming growth factor-β (TGF-β) pathways have been implicated in endothelial cell loss and endothelial to mesenchymal transition of CECs in FECD. Ascorbic acid (AA) is found at high concentrations in FECD and its impact on CEC survival has been investigated. However, how TGF-β and AA effect the composition and rigidity of the CEC's matrix remains unknown. METHODS In this study, we investigated the effect of AA, TGF-β1 and TGF-β3 on the deposition, ultrastructure, stiffness, and composition of the extracellular matrix (ECM) secreted by primary bovine corneal endothelial cells (BCECs). RESULTS Immunofluorescence and electron microscopy post-decellularization demonstrated a robust deposition and distinct structure of ECM in response to treatments. AFM measurements showed that the modulus of the matrix in BCECs treated with TGF-β1 and TGF-β3 was significantly lower than the controls. There was no difference in the stiffness of the matrix between the AA-treated cell and controls. Gene Ontology analysis of the proteomics results revealed that AA modulates the oxidative stress pathway in the matrix while TGF-β induces the expression of matrix proteins collagen IV, laminin, and lysyl oxidase homolog 1. CONCLUSIONS Molecular pathways identified in this study demonstrate the differential role of soluble factors in the pathogenesis of FECD.
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Affiliation(s)
- Iman Jalilian
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA
| | - Santoshi Muppala
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA; Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Maryam Ali
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA
| | - Johnathon D Anderson
- Department of Otolaryngology, School of Medicine, University of California, Davis, Sacramento, CA, 95817, USA
| | - Brett Phinney
- Proteomics Core, University of California, Davis Genome Center, Davis, CA, 95616, USA
| | - Michelle Salemi
- Proteomics Core, University of California, Davis Genome Center, Davis, CA, 95616, USA
| | - Phillip A Wilmarth
- Proteomics Shared Resources, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA; Department of Ophthalmology & Vision Science, School of Medicine, UC Davis Medical Center, Sacramento, CA, 95817, USA
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA; Department of Ophthalmology & Vision Science, School of Medicine, UC Davis Medical Center, Sacramento, CA, 95817, USA.
| | - VijayKrishna Raghunathan
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, 77204, USA; Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX, 77204, USA.
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9
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Salman M, Verma A, Chaurasia S, Prasad D, Kannabiran C, Singh V, Ramappa M. Identification and in silico analysis of a spectrum of SLC4A11 variations in Indian familial and sporadic cases of congenital hereditary endothelial dystrophy. Orphanet J Rare Dis 2022; 17:361. [PMID: 36115991 PMCID: PMC9482203 DOI: 10.1186/s13023-022-02521-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 09/06/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Congenital hereditary endothelial dystrophy (CHED) is a rare form of corneal dystrophy caused by SLC4A11 gene variations. This study aims to find the genetic alterations in SLC4A11, in two Indian familial CHED cases with affected members n = 3 and n = 2 respectively and five sporadic CHED cases using direct sequencing, followed by in silico analysis and characterization of the identified variants.
Results
All three affected members of the first CHED family were identified with a novel homozygous c.1514C > G (p.Ser489Trp) variation while second family showed presence of a compound heterozygous variation c.529A > C (p.Arg161Arg) + c.2461insT (p.Val805fs). Among five sporadic cases, two showed novel changes, homozygous c.1487G > T (p.Ser480Ile) and c.620-2A > G, while the other one had previously reported homozygous c.2653C > T (p.Arg869Cys) variation. The remaining two cases did not reveal the presence of SLC4A11-related pathogenic variations. The identified variations were excluded from the Indian control (n = 80). In silico analysis using homology-based protein modeling and pathogenicity prediction tools, which revealed these alterations as pathogenic, changing their protein stability, local flexibility, residue contact clashes, and the hydrogen bond interactions.
Conclusions
This study contributed to the CHED mutational spectrum, adding four novel variations and confirming a previously reported one. It demonstrates different type of variations in CHED cases, including coding, non-coding, homozygous, synonymous, and compound heterozygous variations. The identified variations revealed different degrees of pathogenic effects in silico. Moreover, two sporadic cases could not be identified with pathogenic variation emphasizing the involvement of other genes or genetic mechanisms.
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10
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Iqbal A, Naz S, Kaul H, Sharif S, Khushbakht A, Naeem MA, Iqtedar M, Kaleem A, Firasat S, Manzoor F. Mutational analysis in sodium-borate cotransporter SLC4A11 in consanguineous families from Punjab, Pakistan. PLoS One 2022; 17:e0273685. [PMID: 36037197 PMCID: PMC9423612 DOI: 10.1371/journal.pone.0273685] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 08/12/2022] [Indexed: 12/02/2022] Open
Abstract
AIM To identify the molecular basis of Congenital Hereditary Endothelial Dystrophy CHED caused by mutations in SLC4A11, in the consanguineous Pakistani families. METHODS A total of 7 consanguineous families affected with Congenital Hereditary Endothelial Dystrophy were diagnosed and registered with the help of ophthalmologists. Blood samples were collected from affected and unaffected members of the enrolled families. Mutational analysis was carried out by DNA sequencing using both Sanger and Whole Exome Sequencing (WES). Probands of each pedigree from the 7 families were used for WES. Results were analyzed with the help of different bioinformatics tools. RESULTS The sequencing results demonstrated three known homozygous mutations in gene SLC4A11 in probands of 7 families. These mutations p.Glu675Ala, p.Val824Met, and p.Arg158fs include 2 missense and 1 frameshift mutation. The mutations result in amino acids that were highly conserved in SLC4A11 across different species. The mutations were segregated with the disease phenotype in the families. CONCLUSION This study reports 3 mutations in 7 families. One of the pathogenic mutations (p.R158fs) was identified for the first time in the Pakistani population. However, two mutations (p.Glu675Ala, p.Val824Met) were previously reported in two and one Pakistani family respectively. As these mutations segregate with the disease phenotype and bioinformatics tool also liable them as pathogenic, they are deemed as probable cause of underlying disease.
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Affiliation(s)
- Afia Iqbal
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
| | - Shagufta Naz
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
| | - Haiba Kaul
- Department of Animal Breeding and Genetics, Genetics Discipline, University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Saima Sharif
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
| | - Aysha Khushbakht
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
| | - Muhammad Asif Naeem
- Vision Impairment Lab of Genetic Diseases Group, Center of Excellence in Molecular Biology, Lahore, Pakistan
| | - Mehwish Iqtedar
- Department of Biotechnology, Lahore College for Women University, Lahore, Pakistan
| | - Afshan Kaleem
- Department of Biotechnology, Lahore College for Women University, Lahore, Pakistan
| | - Sabika Firasat
- Department of Biological Sciences, Quaid-e-Azam University, Islamabad, Pakistan
| | - Farkhanda Manzoor
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
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11
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Souzeau E, Siggs OM, Mullany S, Schmidt JM, Hassall MM, Dubowsky A, Chappell A, Breen J, Bae H, Nicholl J, Hadler J, Kearns LS, Staffieri SE, Hewitt AW, Mackey DA, Gupta A, Burdon KP, Klebe S, Craig JE, Mills RA. Diagnostic yield of candidate genes in an Australian corneal dystrophy cohort. Mol Genet Genomic Med 2022; 10:e2023. [PMID: 35985662 PMCID: PMC9544209 DOI: 10.1002/mgg3.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 07/18/2022] [Indexed: 11/09/2022] Open
Abstract
Corneal dystrophies describe a clinically and genetically heterogeneous group of inherited disorders. The International Classification of Corneal Dystrophies (IC3D) lists 22 types of corneal dystrophy, 17 of which have been demonstrated to result from pathogenic variants in 19 identified genes. In this study, we investigated the diagnostic yield of genetic testing in a well‐characterised cohort of 58 individuals from 44 families with different types of corneal dystrophy. Individuals diagnosed solely with Fuchs endothelial corneal dystrophy were excluded. Clinical details were obtained from the treating ophthalmologist. Participants and their family members were tested using a gene candidate and exome sequencing approach. We identified a likely molecular diagnosis in 70.5% families (31/44). The detection rate was significantly higher among probands with a family history of corneal dystrophy (15/16, 93.8%) than those without (16/28, 57.1%, p = .015), and among those who had undergone corneal graft surgery (9/9, 100.0%) compared to those who had not (22/35, 62.9%, p = .041). We identified eight novel variants in five genes and identified five families with syndromes associated with corneal dystrophies. Our findings highlight the genetic heterogeneity of corneal dystrophies and the clinical utility of genetic testing in reaching an accurate clinical diagnosis.
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Affiliation(s)
- Emmanuelle Souzeau
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - Owen M Siggs
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia.,Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Sean Mullany
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - Joshua M Schmidt
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - Mark M Hassall
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
| | | | - Angela Chappell
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - James Breen
- South Australian Genomics Centre (SAGC), South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia.,Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia.,Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Haae Bae
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
| | | | | | - Lisa S Kearns
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Sandra E Staffieri
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Victoria, Australia.,Department of Ophthalmology, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Alex W Hewitt
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
| | - David A Mackey
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.,Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia, Australia
| | - Aanchal Gupta
- South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia.,Adelaide Eye & Laser Centre, Adelaide, South Australia, Australia
| | - Kathryn P Burdon
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia.,Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia, Australia
| | - Sonja Klebe
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - Richard A Mills
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
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12
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Kannabiran C, Chaurasia S, Ramappa M, Mootha VV. Update on the genetics of corneal endothelial dystrophies. Indian J Ophthalmol 2022; 70:2239-2248. [PMID: 35791103 PMCID: PMC9426112 DOI: 10.4103/ijo.ijo_992_22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Corneal endothelial dystrophies are a heterogeneous group of diseases with different modes of inheritance and genetic basis for each dystrophy. The genes associated with these diseases encode transcription factors, structural components of the stroma and Descemet membrane, cell transport proteins, and others. Congenital hereditary endothelial dystrophy (CHED) is associated with mutations in two genes, OVOL2 and SLC4A11, for dominant and recessive forms of CHED, respectively. Mutations in three genes are known to cause posterior polymorphous corneal dystrophy (PPCD). They are OVOL2 (PPCD1), ZEB1 (PPCD3), and GRHL1 (PPCD4). The PPCD2 locus involving the collagen gene COL8A2 on chromosome 1 is disputed due to insufficient evidence. Mutations in the COL8A2 gene are associated with early-onset Fuchs’ endothelial corneal dystrophy (FECD). Several genes have been associated with the more common, late-onset FECD. Alterations in each of these genes occur in a fraction of patients, and the most prevalent genetic alteration in FECD patients across the world is a triplet repeat expansion in the TCF4 gene. Knowledge of the genetics of corneal endothelial dystrophies has considerably advanced within the last decade and has contributed to better diagnosis of these dystrophies as well as opened up the possibility of novel therapeutic approaches based on the molecular mechanisms involved. The functions of genes identified to date provide insights into the pathogenic mechanisms involved in each disorder.
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Affiliation(s)
- Chitra Kannabiran
- Kallam Anji Reddy Molecular Genetics Laboratory, Prof Brien Holden Eye Research Centre, L.V. Prasad Eye Institute, Hyderabad, Telangana, India
| | - Sunita Chaurasia
- Centre for Rare Eye Diseases and Ocular Genetics; The Cornea Institute; Jasti V Ramanamma Children's Eye Care Center, L.V. Prasad Eye Institute, Kallam Anji Reddy Campus, Hyderabad, Telangana, India
| | - Muralidhar Ramappa
- Centre for Rare Eye Diseases and Ocular Genetics; The Cornea Institute; Jasti V Ramanamma Children's Eye Care Center, L.V. Prasad Eye Institute, Kallam Anji Reddy Campus, Hyderabad, Telangana, India
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13
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Loveridge-Easther C, Kiray G, Hull S, Vincent AL. Harboyan syndrome with biallelic SLC4A11 pathogenic variants misdiagnosed as congenital CMV infection. Ophthalmic Genet 2022; 43:685-688. [DOI: 10.1080/13816810.2022.2083182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
| | - Gulunay Kiray
- Eye Department, Greenlane Clinical Centre, Auckland District Health Board, Auckland, New Zealand
- Department of Ophthalmology, New Zealand National Eye Centre Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Sarah Hull
- Eye Department, Greenlane Clinical Centre, Auckland District Health Board, Auckland, New Zealand
- Department of Ophthalmology, New Zealand National Eye Centre Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Andrea L. Vincent
- Eye Department, Greenlane Clinical Centre, Auckland District Health Board, Auckland, New Zealand
- Department of Ophthalmology, New Zealand National Eye Centre Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
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14
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Genetic profiles of non-syndromic severe-profound hearing loss in Chinese Hans by whole-exome sequencing. Gene 2022; 819:146258. [PMID: 35114279 DOI: 10.1016/j.gene.2022.146258] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 01/07/2022] [Accepted: 01/27/2022] [Indexed: 11/20/2022]
Abstract
Hereditary hearing loss is highly heterogeneous. Despite over 120 non-syndromic deafness genes have been identified, there are still some of novel genes and variants being explored. In the study, we investigated 105 Chinese Han children with non-syndromic, prelingual, severe-profound hearing loss by whole-exome sequencing on DNA samples. The most common deafness gene was GJB2, mainly in variant c.235delC (p.Leu79CysfsTer3). 14 children were identified with pathogenic mutations in three genes, GJB2, SLC26A4, and OTOF. Two mutations have been identified to be pathogenic and not recorded previously, including c.4691G > A (p.Trp1564Ter) and c.3928_3930dup (p.Lys1310dup) in OTOF. The rare variants c.1349G > A (p.Arg450His) and c.456 T > G (p.Asn152Lys) in GSDME, and c.1595G > T (p.Ser532Ile) in SLC26A4 were detected. The frequency of nonsense variant c.2359G > T (p.Glu787Ter) in OTOA was very high in 17 cases. Four of them were identified to be digenic inheritance, including GJB2 and COL4A4, GJB2 and EYA1, GJB2 and COL4A5, and GJB2 and DFNA5. The findings showed that a novel pathogenic variant and rare variants may be associated with severe and profound hearing loss.
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15
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Harboyan Syndrome: A Novel SLC4A11 Variant With Unique Genotype-Phenotype Correlation. Cornea 2022; 41:1053-1057. [PMID: 35439766 DOI: 10.1097/ico.0000000000003023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE The purpose of this study was to describe the genotypic and phenotypic characteristics of an infant with a SLC4A11 mutation associated with bilateral corneal edema, hearing loss, and hydronephrosis present since birth. METHODS This was a case report. Ophthalmic and systemic examination of the proband, histopathologic and ultrastructural characteristics of bilateral corneal discs, and molecular genetic evaluation by whole-exome sequencing are described. RESULTS A male infant was born with bilateral corneal opacities, sensorineural hearing loss, and hydronephrosis to healthy parents after an uneventful pregnancy. Penetrating keratoplasty of the left eye at age 10 months demonstrated minimal corneal edema with normal thickness Descemet membrane and cellular endothelium with intracytoplasmic vacuoles and degenerative changes in rare cells. Penetrating keratoplasty of the right eye 6 months later disclosed prominent corneal edema with a thickened posterior banded layer of Descemet membrane and severe endothelial atrophy. Whole-exome sequencing of the proband and parents' blood demonstrated a homozygous mutation in SLC4A11 gene (c.1735_1737delCTC,p.Leu579del). The combined clinical, histopathologic, and molecular genetic findings raised consideration of an unusual phenotype of Harboyan syndrome manifesting as congenital hereditary endothelial dystrophy with a prelingual rather than, as previously described, postlingual hearing loss. CONCLUSIONS We report a novel homozygous SLC4A11 variant with a previously undocumented phenotype of CHED in association with prelingual sensorineural hearing loss and hydronephrosis, thus broadening our understanding of the spectrum of genotypic and phenotypic findings of Harboyan syndrome.
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16
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Qian F, Jiang X, Chai R, Liu D. The Roles of Solute Carriers in Auditory Function. Front Genet 2022; 13:823049. [PMID: 35154281 PMCID: PMC8827148 DOI: 10.3389/fgene.2022.823049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 01/03/2022] [Indexed: 11/13/2022] Open
Abstract
Solute carriers (SLCs) are important transmembrane transporters with members organized into 65 families. They play crucial roles in transporting many important molecules, such as ions and some metabolites, across the membrane, maintaining cellular homeostasis. SLCs also play important roles in hearing. It has been found that mutations in some SLC members are associated with hearing loss. In this review, we summarize SLC family genes related with hearing dysfunction to reveal the vital roles of these transporters in auditory function. This summary could help us understand the auditory physiology and the mechanisms of hearing loss and further guide future studies of deafness gene identification.
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Affiliation(s)
- Fuping Qian
- School of Life Sciences, Nantong University, Nantong, China
| | - Xiaoge Jiang
- Department of Rehabilitation Medicine, The Second People's Hospital of Nantong, Affiliated Rehabilitation Hospital of Nantong University, Nantong, China
| | - Renjie Chai
- State Key Laboratory of Bioelectronics, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, Southeast University, Nanjing, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing, China.,Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing, China.,Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Dong Liu
- School of Life Sciences, Nantong University, Nantong, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
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17
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Altered gene expression in slc4a11 -/- mouse cornea highlights SLC4A11 roles. Sci Rep 2021; 11:20885. [PMID: 34686736 PMCID: PMC8536660 DOI: 10.1038/s41598-021-98921-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 09/13/2021] [Indexed: 11/17/2022] Open
Abstract
SLC4A11 is a H+/NH3/water transport protein, of corneal endothelial cells. SLC4A11 mutations cause congenital hereditary endothelial dystrophy and some cases of Fuchs endothelial corneal dystrophy. To probe SLC4A11’s roles, we compared gene expression in RNA from corneas of 17-week-old slc4a11−/− (n = 3) and slc4a11+/+ mice (n = 3) and subjected to RNA sequencing. mRNA levels for a subset of genes were also assessed by quantitative real-time reverse transcription PCR (qRT RT-PCR). Cornea expressed 13,173 genes, which were rank-ordered for their abundance. In slc4a11−/− corneas, 100 genes had significantly altered expression. Abundant slc14a1 expression, encoding the urea transporter UT-A, suggests a significant role in the cornea. The set of genes with altered expression was subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, revealing that alterations clustered into extracellular region, cytoskeleton, cell adhesion and plasma membrane functions. Gene expression changes further clustered into classes (with decreasing numbers of genes): cell fate and development, extracellular matrix and cell adhesion, cytoskeleton, ion homeostasis and energy metabolism. Together these gene changes confirm earlier suggestions of a role of SLC4A11 in ion homeostasis, energy metabolism, cell adhesion, and reveal an unrecognized SLC4A11 role in cytoskeletal organization.
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18
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SLC4A11 mutations causative of congenital hereditary endothelial dystrophy (CHED) progressing to Harboyan syndrome in consanguineous Pakistani families. Mol Biol Rep 2021; 48:7467-7476. [PMID: 34637099 DOI: 10.1007/s11033-021-06765-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 08/17/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Autosomal recessive corneal hereditary endothelial dystrophy (CHED) is a rare congenital disorder of cornea. Mutations in SLC4A11 gene are associated with CHED phenotype. CHED is also an early feature of Harboyan syndrome. The aim of the present study was to identify genetic mutations in the SLC4A11 gene in CHED cases belonging to inbred Pakistani families. Furthermore, all homozygous mutation carriers were investigated for hearing deficit. METHODS AND RESULTS This study included consanguineous CHED families presented at Al-Shifa Trust Eye Hospital, Rawalpindi, Pakistan from June 2018 to September 2018. DNA was extracted from blood samples. Direct sequencing of SLC4A11 gene was performed. All identified variants were evaluated by in silico programs i.e., SIFT, PolyPhen-2, and MutationTaster. Pathogenicity of the two identified splice site variants was analyzed by Human Splicing Finder and MaxEnt Scan. Screening of five CHED families revealed a total of three previously un reported (p.Arg128Gly, c.2241-2A > T and c.1898-2A > C in family CHED19, CHED22 and CHED26 respectively) and two already reported homozygous disease causing variants (p.Arg869Cys and p.Val824Met in family CHED24 and CHED25 respectively) as predicted by mutation taster. All of these variants segregated with disease phenotype and were not detected in controls. CONCLUSION Affected individuals of the five CHED families screened in this study had the disease due to SLC4A11 mutations and progressing to Harboyan syndrome. Identification of previously unreported mutations aid to heterogeneity of SLC4A11 and CHED pathogenesis as well as helped to provide genetic counseling to affected families.
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Chibani Z, Abid IZ, Söderkvist P, Feki J, Aifa MH. Autosomal recessive congenital hereditary corneal dystrophy associated with a novel SLC4A11 mutation in two consanguineous Tunisian families. Br J Ophthalmol 2021; 106:281-287. [PMID: 33879471 DOI: 10.1136/bjophthalmol-2020-318204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/11/2021] [Accepted: 03/20/2021] [Indexed: 11/03/2022]
Abstract
BACKGROUND Autosomal recessive congenital hereditary corneal dystrophy (CHED) is a rare isolated developmental anomaly of the eye characterised by diffuse bilateral corneal clouding that may lead to visual impairment requiring corneal transplantation. CHED is known to be caused by mutations in the solute carrier family 4 member 11 (SLC4A11) gene which encodes a membrane transporter protein (sodium bicarbonate transporter-like solute carrier family 4 member 11). METHODS To identify SLC4A11 gene mutations associated with CHED (OMIM: #217700), genomic DNA was extracted from whole blood and sequenced for all exons and intron-exon boundaries in two large Tunisian families. RESULTS A novel deletion SLC4A11 mutation (p. Leu479del; c.1434_1436del) is responsible for CHED in both analysed families. This non-frameshift mutation was found in a homozygous state in affected members and heterozygous in non-affected members. In silico analysis largely support the pathogenicity of this alteration that may leads to stromal oedema by disrupting the osmolarity balance. Being localised to a region of alpha-helical secondary structure, Leu479 deletion may induce protein-compromising structural rearrangements. CONCLUSION To the best of our knowledge, this is the first clinical and genetic study exploring CHED in Tunisia. The present work also expands the list of pathogenic genotypes in SLC4A11 gene and its associated clinical diagnosis giving more insights into genotype-phenotype correlations.
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Affiliation(s)
- Zohra Chibani
- Molecular and Functional Genetics Laboratory, University of Sfax, Faculty of Science of Sfax, Sfax, Tunisia
| | - Imen Zone Abid
- Department of Ophthalmology, Habib Bourguiba University Hospital, University of Sfax, Sfax, Tunisia
| | - Peter Söderkvist
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Jamel Feki
- Department of Ophthalmology, Habib Bourguiba University Hospital, University of Sfax, Sfax, Tunisia
| | - Mounira Hmani Aifa
- Molecular and Functional Genetics Laboratory, University of Sfax, Faculty of Science of Sfax, Sfax, Tunisia
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20
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Ptosis, ophthalmoplegia and corneal endothelial disease - ocular manifestations of mitochondrial disease. Am J Ophthalmol Case Rep 2021; 22:101073. [PMID: 33869891 PMCID: PMC8041719 DOI: 10.1016/j.ajoc.2021.101073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 02/03/2021] [Accepted: 03/07/2021] [Indexed: 11/20/2022] Open
Abstract
Purpose To describe two patients with bilateral ptosis, ophthalmoplegia, cataracts and corneal endothelial disease requiring corneal transplantation. Observations Histopathological analysis of muscle biopsy samples from both patients identified features consistent with a mitochondrial cytopathy. A single multigenic mitochondrial deoxyribonucleic acid (DNA) deletion was detected in the first patient. Pathogenic mutations in the POLG gene which codes for mitochondrial DNA polymerase, tasked with replicating the mitochondrial genome were identified in the second patient. Conclusion The collection of clinical features present in both cases described can be explained by a diagnosis of mitochondrial disease. Importance Corneal endothelial disease, in addition to ptosis, ophthalmoplegia, cataract, pigmentary retinopathy and optic atrophy should be recognised as a feature of mitochondrial disease.
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Key Words
- ATP, Adenosine triphosphate
- CHED, Congenital hereditary endothelial dystrophy
- COX, Cytochrome oxidase
- CPEO, Chronic progressive external ophthalmoplegia
- Corneal endothelial disease
- DNA, Deoxyribonucleic acid
- DSAEK, Descemet's stripping automated endothelial keratoplasty
- FECD, Fuchs endothelial corneal dystrophy
- LF, Levator palpebrae superioris function
- MELAS syndrome, Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke
- MRD1, Margin reflex 1 distance
- MT-ATP6, Mitochondrially encoded adenosine triphosphate synthase membrane subunit 6
- MT-TP, Mitochondrially encoded transfer ribonucleic acid proline
- Mitochondrial disease
- Ophthalmoplegia
- Ptosis
- RNA, Ribonucleic acid
- SDH, Succinic dehydrogenase
- TRNA, Transfer ribonucleic acid
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Zhang W, Frausto R, Chung DD, Griffis CG, Kao L, Chen A, Azimov R, Sampath AP, Kurtz I, Aldave AJ. Energy Shortage in Human and Mouse Models of SLC4A11-Associated Corneal Endothelial Dystrophies. Invest Ophthalmol Vis Sci 2021; 61:39. [PMID: 32721020 PMCID: PMC7425690 DOI: 10.1167/iovs.61.8.39] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose To elucidate the molecular events in solute carrier family 4 member 11 (SLC4A11)-deficient corneal endothelium that lead to the endothelial dysfunction that characterizes the dystrophies associated with SLC4A11 mutations, congenital hereditary endothelial dystrophy (CHED) and Fuchs endothelial corneal dystrophy 4. Methods Comparative transcriptomic analysis (CTA) was performed in primary human corneal endothelial cells (pHCEnC) and murine corneal endothelial cells (MCEnC) with normal and reduced levels of SLC4A11 (SLC4A11 KD pHCEnC) and Slc4a11 (Slc4a11−/− MCEnC), respectively. Validation of differentially expressed genes was performed using immunofluorescence staining of CHED corneal endothelium, as well as western blot and quantitative PCR analysis of SLC4A11 KD pHCEnC and Slc4a11−/− MCEnC. Functional analyses were performed to investigate potential functional changes associated with the observed transcriptomic alterations. Results CTA revealed inhibition of cell metabolism and ion transport function as well as mitochondrial dysfunction, leading to reduced adenosine triphosphate (ATP) production, in SLC4A11 KD pHCEnC and Slc4a11−/− MCEnC. Co-localization of SNARE protein STX17 with mitochondria marker COX4 was observed in CHED corneal endothelium, as was activation of AMPK–p53/ULK1 in both SLC4A11 KD pHCEnC and Slc4a11−/− MCEnC, providing additional evidence of mitochondrial dysfunction and mitophagy. Reduced Na+-dependent HCO3− transport activity and altered NH4Cl-induced membrane potential changes were observed in Slc4a11−/− MCEnC. Conclusions Reduced steady-state ATP levels and subsequent activation of the AMPK–p53 pathway provide a link between the metabolic functional deficit and transcriptome alterations, as well as evidence of insufficient ATP to maintain the Na+/K+-ATPase corneal endothelial pump as the cause of the edema that characterizes SLC4A11-associated corneal endothelial dystrophies.
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Quade BN, Marshall A, Parker MD. pH dependence of the Slc4a11-mediated H + conductance is influenced by intracellular lysine residues and modified by disease-linked mutations. Am J Physiol Cell Physiol 2020; 319:C359-C370. [PMID: 32520610 DOI: 10.1152/ajpcell.00128.2020] [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] [Indexed: 02/03/2023]
Abstract
SLC4A11 is the only member of the SLC4 family that transports protons rather than bicarbonate. SLC4A11 is expressed in corneal endothelial cells, and its mutation causes corneal endothelial dystrophy, although the mechanism of pathogenesis is unknown. We previously demonstrated that the magnitude of the H+ conductance (Gm) mediated by SLC4A11 is increased by rises in intracellular as well as extracellular pH (pHi and pHe). To better understand this feature and whether it is altered in disease, we studied the pH dependence of wild-type and mutant mouse Slc4a11 expressed in Xenopus oocytes. Using voltage-clamp circuitry in conjunction with a H+-selective microelectrode and a microinjector loaded with NaHCO3, we caused incremental rises in oocyte pHi and measured the effect on Gm. We find that the rise of Gm has a steeper pHi dependence at pHe =8.50 than at pHe =7.50. Data gathered at pHe =8.50 can be fit to the Hill equation enabling the calculation of a pK value that reports pHi dependence. We find that mutation of lysine residues that are close to the first transmembrane span (TM1) causes an alkaline shift in pK. Furthermore, two corneal-dystrophy-causing mutations close to the extracellular end of TM1, E399K and T401K (E368K and T370K in mouse), cause an acidic shift in pK, while a third mutation in the fourth intracellular loop, R804H (R774H in mouse), causes an alkaline shift in pK. This is the first description of determinants of SLC4A11 pH dependence and the first indication that a shift in pH dependence could modify disease expressivity in some cases of corneal dystrophy.
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Affiliation(s)
- Bianca N Quade
- Department of Physiology and Biophysics, The State University of New York: The University at Buffalo, Buffalo, New York
| | - Aniko Marshall
- Department of Physiology and Biophysics, The State University of New York: The University at Buffalo, Buffalo, New York
| | - Mark D Parker
- Department of Physiology and Biophysics, The State University of New York: The University at Buffalo, Buffalo, New York.,Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo: The State University of New York, Buffalo, New York.,State University of New York Eye Institute, University at Buffalo: The State University of New York, Buffalo, New York
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23
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Wang H, Zhao H, Sun K, Huang X, Jin L, Feng J. Evolutionary Basis of High-Frequency Hearing in the Cochleae of Echolocators Revealed by Comparative Genomics. Genome Biol Evol 2020; 12:3740-3753. [PMID: 31730196 PMCID: PMC7145703 DOI: 10.1093/gbe/evz250] [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] [Accepted: 11/14/2019] [Indexed: 12/25/2022] Open
Abstract
High-frequency hearing is important for the survival of both echolocating bats and whales, but our understanding of its genetic basis is scattered and segmented. In this study, we combined RNA-Seq and comparative genomic analyses to obtain insights into the comprehensive gene expression profile of the cochlea and the adaptive evolution of hearing-related genes. A total of 144 genes were found to have been under positive selection in various species of echolocating bats and toothed whales, 34 of which were identified to be related to hearing behavior or auditory processes. Subsequently, multiple physiological processes associated with those genes were found to have adaptively evolved in echolocating bats and toothed whales, including cochlear bony development, antioxidant activity, ion balance, and homeostatic processes, along with signal transduction. In addition, abundant convergent/parallel genes and sites were detected between different pairs of echolocator species; however, no specific hearing-related physiological pathways were enriched by them and almost all of the convergent/parallel signals were selectively neutral, as previously reported. Notably, two adaptive parallel evolved sites in TECPR2 were shown to have been under positive selection, indicating their functional importance for the evolution of echolocation and high-frequency hearing in laryngeal echolocating bats. This study deepens our understanding of the genetic bases underlying high-frequency hearing in the cochlea of echolocating bats and toothed whales.
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Affiliation(s)
- Hui Wang
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China.,College of Life Science, Jilin Agricultural University, Changchun, China
| | - Hanbo Zhao
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China
| | - Keping Sun
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China
| | - Xiaobin Huang
- Vector Laboratory for Zoonosis Control and Prevention, Dali University, China
| | - Longru Jin
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China
| | - Jiang Feng
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China.,College of Life Science, Jilin Agricultural University, Changchun, China
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24
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Brejchova K, Dudakova L, Skalicka P, Dobrovolny R, Masek P, Putzova M, Moosajee M, Tuft SJ, Davidson AE, Liskova P. IPSC-Derived Corneal Endothelial-like Cells Act as an Appropriate Model System to Assess the Impact of SLC4A11 Variants on Pre-mRNA Splicing. Invest Ophthalmol Vis Sci 2019; 60:3084-3090. [PMID: 31323090 PMCID: PMC6645617 DOI: 10.1167/iovs.19-26930] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Purpose To report molecular genetic findings in six probands with congenital hereditary endothelial dystrophy (CHED) variably associated with hearing loss (also known as Harboyan syndrome). Furthermore, we developed a cellular model to determine if disease-associated variants induce aberrant SLC4A11 pre-mRNA splicing. Methods Direct sequencing of the entire SLC4A11 coding region was performed in five probands. In one individual, whole genome sequencing was undertaken. The effect of c.2240+5G>A on pre-mRNA splicing was evaluated in a corneal endothelial-like (CE-like) cell model expressing SLC4A11. CE-like cells were derived from autologous induced pluripotent stem cells (iPSCs) via neural crest cells exposed to B27, PDGF-BB, and DKK-2. Total RNA was extracted, and RT-PCR was performed followed by Sanger and a targeted next generation sequencing (NGS) approach to identify and quantify the relative abundance of alternatively spliced transcripts. Results In total, 11 different mutations in SLC4A11 evaluated as pathogenic were identified; of these, c.1237G>A, c.2003T>C, c.1216+1G>A, and c.2240+5G>A were novel. The c.2240+5G>A variant was demonstrated to result in aberrant pre-mRNA splicing. A targeted NGS approach confirmed that the variant introduces a leaky cryptic splice donor site leading to the production of a transcript containing an insertion of six base pairs with the subsequent introduction of a premature stop codon (p.Thr747*). Furthermore, a subset of transcripts comprising full retention of intron 16 also were observed, leading to the same functionally null allele. Conclusions This proof-of-concept study highlights the potential of using CE-like cells to investigate the pathogenic consequences of SLC4A11 disease–associated variants.
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Affiliation(s)
- Kristyna Brejchova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
| | - Lubica Dudakova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
| | - Pavlina Skalicka
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic.,Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Robert Dobrovolny
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
| | - Petr Masek
- Clinic of Ophthalmology, University Hospital Ostrava, Ostrava, Czech Republic.,Department of Craniofacial Surgery, University of Ostrava, Ostrava, Czech Republic
| | | | - Mariya Moosajee
- UCL Institute of Ophthalmology, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.,Great Ormond Street Hospital for Children, London, United Kingdom
| | - Stephen J Tuft
- UCL Institute of Ophthalmology, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| | | | - Petra Liskova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic.,Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic.,UCL Institute of Ophthalmology, London, United Kingdom
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25
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Kao L, Azimov R, Shao XM, Abuladze N, Newman D, Zhekova H, Noskov S, Pushkin A, Kurtz I. SLC4A11 function: evidence for H +(OH -) and NH 3-H + transport. Am J Physiol Cell Physiol 2019; 318:C392-C405. [PMID: 31774702 PMCID: PMC7052617 DOI: 10.1152/ajpcell.00425.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Whether SLC4A11 transports ammonia and its potential mode of ammonia transport (NH4+, NH3, or NH3-2H+ transport have been proposed) are controversial. In the absence of ammonia, whether SLC4A11 mediates significant conductive H+(OH-) transport is also controversial. The present study was performed to determine the mechanism of human SLC4A11 ammonia transport and whether the transporter mediates conductive H+(OH-) transport in the absence of ammonia. We quantitated H+ flux by monitoring changes in intracellular pH (pHi) and measured whole cell currents in patch-clamp studies of HEK293 cells expressing the transporter in the absence and presence of NH4Cl. Our results demonstrate that SLC4A11 mediated conductive H+(OH-) transport that was stimulated by raising the extracellular pH (pHe). Ammonia-induced HEK293 whole cell currents were also stimulated by an increase in pHe. In studies using increasing NH4Cl concentrations with equal NH4+ extracellular and intracellular concentrations, the shift in the reversal potential (Erev) due to the addition of ammonia was compatible with NH3-H+ transport competing with H+(OH-) rather than NH3-nH+ (n ≥ 2) transport. The increase in equivalent H+(OH-) flux observed in the presence of a transcellular H+ gradient was also compatible with SLC4A11-mediated NH3-H+ flux. The NH3 versus Erev data fit a theoretical model suggesting that NH3-H+ and H+(OH-) competitively interact with the transporter. Studies of mutant SLC4A11 constructs in the putative SLC4A11 ion coordination site showed that both H+(OH-) transport and ammonia-induced whole cell currents were blocked suggesting that the H+(OH-) and NH3-H+ transport processes share common features involving the SLC4A11 transport mechanism.
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Affiliation(s)
- Liyo Kao
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Rustam Azimov
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Xuesi M Shao
- Department of Neurobiology, University of California, Los Angeles, California
| | - Natalia Abuladze
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Debra Newman
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Hristina Zhekova
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada
| | - Sergei Noskov
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada
| | - Alexander Pushkin
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ira Kurtz
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California.,Brain Research Institute, University of California, Los Angeles, California
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26
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Coexistence of Congenital Hereditary Endothelial Dystrophy and Fuchs Endothelial Corneal Dystrophy Associated With SLC4A11 Mutations in Affected Families. Cornea 2019; 39:354-357. [DOI: 10.1097/ico.0000000000002183] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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27
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Homeostasis of SLC4A11 protein is mediated by endoplasmic reticulum-associated degradation. Exp Eye Res 2019; 188:107782. [DOI: 10.1016/j.exer.2019.107782] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/17/2019] [Accepted: 08/28/2019] [Indexed: 01/12/2023]
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28
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Malhotra D, Loganathan SK, Chiu AM, Lukowski CM, Casey JR. Human Corneal Expression of SLC4A11, a Gene Mutated in Endothelial Corneal Dystrophies. Sci Rep 2019; 9:9681. [PMID: 31273259 PMCID: PMC6609610 DOI: 10.1038/s41598-019-46094-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 06/21/2019] [Indexed: 12/21/2022] Open
Abstract
Two blinding corneal dystrophies, pediatric-onset congenital hereditary endothelial dystrophy (CHED) and some cases of late-onset Fuchs endothelial corneal dystrophy (FECD), are caused by SLC4A11 mutations. Three N-terminal SLC4A11 variants: v1, v2 and v3 are expressed in humans. We set out to determine which of these transcripts and what translated products, are present in corneal endothelium as these would be most relevant for CHED and FECD studies. Reverse transcription PCR (RT-PCR) and quantitative RT-PCR revealed only v2 and v3 mRNA in human cornea, but v2 was most abundant. Immunoblots probed with variant-specific antibodies revealed that v2 protein is about four times more abundant than v3 in human corneal endothelium. Bioinformatics and protein analysis using variant-specific antibodies revealed that second methionine in the open reading frame (M36) acts as translation initiation site on SLC4A11 v2 in human cornea. The v2 variants starting at M1 (v2-M1) and M36 (v2-M36) were indistinguishable in their cell surface trafficking and transport function (water flux). Structural homology models of v2-M36 and v3 suggest structural differences but their significance remains unclear. A combination of bioinformatics, RNA quantification and isoform-specific antibodies allows us to conclude that SLC4A11 variant 2 with start site M36 is predominant in corneal endothelium.
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Affiliation(s)
- Darpan Malhotra
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Sampath K Loganathan
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.,Lunenfeld-Tanenbaum Research Institute, Toronto, Ontario, M5G 1X5, Canada
| | - Anthony M Chiu
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Chris M Lukowski
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Joseph R Casey
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.
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29
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Nanda GG, Alone DP. REVIEW: Current understanding of the pathogenesis of Fuchs' endothelial corneal dystrophy. Mol Vis 2019; 25:295-310. [PMID: 31263352 PMCID: PMC6571125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 06/03/2019] [Indexed: 11/18/2022] Open
Abstract
Fuchs' endothelial corneal dystrophy (FECD) is the most prominent reason for corneal-endothelial transplantations across the globe. The disease pathophysiology manifests through a combination of various genetic and non-heritable factors. This review provides a comprehensive list of known genetic players that cause FECD, and discusses the prominent pathological features that participate in disease progression, such as channel dysfunction, abnormal extracellular matrix deposition, RNA toxicity, oxidative stress, and apoptosis. Although current practices to correct visual acuity involve surgical intervention, this review also discusses the scope of various non-surgical therapeutics to remedy FECD.
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30
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Gee MT, Kurtz I, Pannabecker TL. Expression of SLC4A11 protein in mouse and rat medulla: a candidate transporter involved in outer medullary ammonia recycling. Physiol Rep 2019; 7:e14089. [PMID: 31124301 PMCID: PMC6533174 DOI: 10.14814/phy2.14089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Accepted: 04/10/2019] [Indexed: 01/27/2023] Open
Abstract
SLC4A11 is a multifunctional membrane transporter involved with H+ transport, NH3 and alkaline pH stimulated H+ transport, and water transport. The role of SLC4A11 in the kidney is not well understood. A prior study has shown that in murine kidney, SLC4A11/LacZ staining is primarily in the long-looped descending thin limb (DTL) as determined by colocalization with aquaporin 1 (AQP1), a protein that is expressed in some, but not all, descending thin limb segments. Using a previously characterized polyclonal antibody, we demonstrate the selective expression of SLC4A11 in the upper DTLs (which are AQP1-positive) in the outer medulla and inner medulla with little or no expression in the lower DTLs (which are AQP-1-null). SLC4A11 also colocalized with AQP1 and the urea transporter UT-B in the mouse descending vasa recta, but was absent in mouse and rat ascending vasa recta. Mouse, but not rat, outer medullary collecting duct cells also labeled for SLC4A11. Our results are compatible with the hypothesis that in the inner stripe of the outer medulla, SLC4A11 plays a role in the countercurrent transport of ammonia absorbed from the outer medullary thick ascending limb and secreted into the long-looped DTLs. SLC4A11 can potentially modulate the rate of ammonia transport in the mouse outer medullary collecting duct. Our data suggest functionally unique SLC4A11 pathways in mouse and rat and complement previous studies of DTL Na+ , urea and water permeability indicating that the upper and lower DTLs of long-looped nephrons are functionally distinct.
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Affiliation(s)
- Michael T. Gee
- Department of PhysiologyBanner‐University Medical CenterUniversity of ArizonaTucsonAZ85724
| | - Ira Kurtz
- Division of NephrologyDavid Geffen School of MedicineUniversity of California, Los Angeles (UCLA)Los AngelesCA
- Brain Research InstituteDavid Geffen School of MedicineUniversity of California, Los Angeles (UCLA)Los AngelesCA
| | - Thomas L. Pannabecker
- Department of PhysiologyBanner‐University Medical CenterUniversity of ArizonaTucsonAZ85724
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31
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Huebner AK, Maier H, Maul A, Nietzsche S, Herrmann T, Praetorius J, Hübner CA. Early Hearing Loss upon Disruption of Slc4a10 in C57BL/6 Mice. J Assoc Res Otolaryngol 2019; 20:233-245. [PMID: 31001720 DOI: 10.1007/s10162-019-00719-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/25/2019] [Indexed: 12/13/2022] Open
Abstract
The unique composition of the endolymph with a high extracellular K+ concentration is essential for sensory transduction in the inner ear. It is secreted by a specialized epithelium, the stria vascularis, that is connected to the fibrocyte meshwork of the spiral ligament in the lateral wall of the cochlea via gap junctions. In this study, we show that in mice the expression of the bicarbonate transporter Slc4a10/Ncbe/Nbcn2 in spiral ligament fibrocytes starts shortly before hearing onset. Its disruption in a C57BL/6 background results in early onset progressive hearing loss. This hearing loss is characterized by a reduced endocochlear potential from hearing onset onward and progressive degeneration of outer hair cells. Notably, the expression of a related bicarbonate transporter, i.e., Slc4a7/Nbcn1, is also lost in spiral ligament fibrocytes of Slc4a10 knockout mice. The histological analysis of the spiral ligament of Slc4a10 knockout mice does not reveal overt fibrocyte loss as reported for Slc4a7 knockout mice. The ultrastructural analysis, however, shows mitochondrial alterations in fibrocytes of Slc4a10 knockout mice. Our data suggest that Slc4a10 and Slc4a7 are functionally related and essential for inner ear homeostasis.
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Affiliation(s)
- Antje K Huebner
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller Universität, Am Klinikum 1, 07747, Jena, Germany
| | - Hannes Maier
- Department of Otolaryngology and Cluster of Excellence Hearing4all, Deutsches HörZentrum Hannover, Medical University Hannover, Karl-Wiechert-Allee 3, 30625, Hannover, Germany
| | - Alena Maul
- Max-Delbrück Centrum für Molekulare Medizin (MDC) and NeuroCure, Robert-Rössle-Str. 10, 13092, Berlin, Germany
| | - Sandor Nietzsche
- Electron Microscopy Center, Jena University Hospital, Friedrich Schiller Universität, Ziegelmühlenweg 1, 07743, Jena, Germany
| | - Tanja Herrmann
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller Universität, Am Klinikum 1, 07747, Jena, Germany
| | - Jeppe Praetorius
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark
| | - Christian A Hübner
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller Universität, Am Klinikum 1, 07747, Jena, Germany.
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Alka K, Casey JR. Ophthalmic Nonsteroidal Anti-Inflammatory Drugs as a Therapy for Corneal Dystrophies Caused by SLC4A11 Mutation. Invest Ophthalmol Vis Sci 2019; 59:4258-4267. [PMID: 30140924 DOI: 10.1167/iovs.18-24301] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose SLC4A11 is a plasma membrane protein of corneal endothelial cells. Some mutations of the SLC4A11 gene result in SLC4A11 protein misfolding and failure to mature to the plasma membrane. This gives rise to some cases of Fuchs' endothelial corneal dystrophy (FECD) and congenital hereditary endothelial dystrophy (CHED). We screened ophthalmic nonsteroidal anti-inflammatory drugs (NSAIDs) for their ability to correct SLC4A11 folding defects. Methods Five ophthalmic NSAIDs were tested for their therapeutic potential in some genetic corneal dystrophy patients. HEK293 cells expressing CHED and FECD-causing SLC4A11 mutants were grown on 96-well dishes in the absence or presence of NSAIDs. Ability of NSAIDs to correct mutant SLC4A11 cell-surface trafficking was assessed with a bioluminescence resonance energy transfer (BRET) assay and by confocal microscopy. The ability of mutant SLC4A11-expressing cells to mediate water flux (SLC4A11 mediates water flux across the corneal endothelial cell basolateral membrane as part of the endothelial water pump) was measured upon treatment with ophthalmic NSAIDs. Results BRET-assays revealed significant rescue of SLC4A11 mutants to the cell surface by 4 of 5 NSAIDs tested. The NSAIDs, diclofenac and nepafenac, were effective in moving endoplasmic reticulum-retained missense mutant SLC4A11 to the cell surface, as measured by confocal immunofluorescence. Among intracellular-retained SLC4A11 mutants, 20 of 30 had significant restoration of cell surface abundance upon treatment with diclofenac. Diclofenac restored mutant SLC4A11 water flux activity to the level of wild-type SLC4A11 in some cases. Conclusions These results encourage testing diclofenac eye drops as a treatment for corneal dystrophy in patients whose disease is caused by some SLC4A11 missense mutations.
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Affiliation(s)
- Kumari Alka
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph R Casey
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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Romero PT, Donoso R, López P, Miranda A, Rodríguez L, Chrzanowsky D, Asenjo MS, Burgos G, Villegas P, Desir J, Moya G, Herrera LM. Clinical features and possible founder mutation of the 8bp duplication mutation in the SLC4A11 gene causing corneal dystrophy and perceptive deafness in three South American families. Ophthalmic Genet 2019; 40:91-98. [PMID: 30856043 DOI: 10.1080/13816810.2019.1571615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND Corneal Dystrophy and Perceptive Deafness (CDPD) or Harboyan syndrome is an autosomal recessive rare disorder, characterized by congenital corneal opacities and progressive sensorineural hearing loss, which usually begins after the second decades of life. This study reports the ophthalmic, audiological and genetic features, in five CDPD affected patients from three Chilean families. MATERIALS AND METHODS Five individuals affected with CDPD from three unrelated Chilean families were clinically and genetically examined. To evaluate a putative founder mutation 7 SNPs were analyzed in the three families, an Argentinian patient (carrier of the same mutation previously reported) and 87 Chilean controls. RESULTS The ophthalmic symptoms in the five patients were bilateral and symmetric, starting before one year of age, and visual acuity varied from 0.1 to 0.3. In all cases, hearing loss began over 8 years old. The sequence of the 19 exons of SLC4A11 gene of all the affected patients exhibited homozygous eight nucleotide sequence duplication (c.2233_2240dup TATGACAC, p.(Ile748Metfs*5)) at the end of exon 16. All the affected patients of the three families were homozygous for a haplotype composed of five SNPs and covering 4,1 Mb. The same haplotype was present in one allele of the heterozygous Argentinean patient and has a frequency of 2.76% in Chilean population. CONCLUSIONS The five CDPD patients were homozygous for the same mutation in the SLC4A11 gene. Haplotype analysis of all the affected, including the case reported from Argentina was in accordance with a founder mutation.
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Affiliation(s)
- Pablo T Romero
- a Hospital Clínico Universidad de Chile José Joaquín Aguirre , Santiago , Chile
| | - Rodrigo Donoso
- b Servicio de Oftalmología , Hospital del Salvador , Santiago , Chile
| | - Pamela López
- c Programa de Genética Humana, ICBM, Facultad de Medicina , Universidad de Chile , Santiago , Chile
| | - Ana Miranda
- c Programa de Genética Humana, ICBM, Facultad de Medicina , Universidad de Chile , Santiago , Chile
| | - Leandro Rodríguez
- d Servicio de Otorrinolaringología , Hospital del Salvador , Santiago , Chile
| | - Dominique Chrzanowsky
- c Programa de Genética Humana, ICBM, Facultad de Medicina , Universidad de Chile , Santiago , Chile
| | - Maria S Asenjo
- c Programa de Genética Humana, ICBM, Facultad de Medicina , Universidad de Chile , Santiago , Chile
| | - Gonzalo Burgos
- c Programa de Genética Humana, ICBM, Facultad de Medicina , Universidad de Chile , Santiago , Chile
| | - Pablo Villegas
- e Servicio de Anatomía Patológica , Hospital del Salvador , Santiago , Chile
| | - Julie Desir
- f Department of Medical Genetics , Hôpital Erasme, ULB , Brussels , Belgium
| | | | - Luisa M Herrera
- c Programa de Genética Humana, ICBM, Facultad de Medicina , Universidad de Chile , Santiago , Chile
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Sarnicola C, Farooq AV, Colby K. Fuchs Endothelial Corneal Dystrophy: Update on Pathogenesis and Future Directions. Eye Contact Lens 2019; 45:1-10. [DOI: 10.1097/icl.0000000000000469] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Reed NS, Deal JA, Huddle MG, Betz JF, Bailey BE, McGlumphy EJ, Eghrari AO, Riazuddin SA, Lin FR, Gottsch JD. Pilot Study of Audiometric Patterns in Fuchs Corneal Dystrophy. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2018; 61:2604-2608. [PMID: 30286242 PMCID: PMC6428237 DOI: 10.1044/2018_jslhr-h-18-0088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/11/2018] [Accepted: 06/05/2018] [Indexed: 06/08/2023]
Abstract
PURPOSE Although Fuchs corneal dystrophy (FCD) is considered an eye disease, a small number of studies have identified genes related to both FCD and hearing loss. Whether FCD is related to hearing loss is unknown. METHOD This is a case-control study comparing pure-tone audiometry hearing thresholds in 180 patients with FCD from a hospital-based ophthalmology clinic with 2,575 population-based controls from a nationally representative survey, the National Health and Nutrition Examination Survey (from cycles 2005-06 and 2009-10). Generalized estimating equations were used to compare mean better-hearing ear thresholds in the 2 groups adjusted for age, sex, race, and noise exposure. RESULTS Patients with FCD had higher hearing thresholds (worse hearing) in lower frequencies (mean difference at 0.5 kHz = 3.49 dB HL) and lower hearing thresholds (better hearing) in higher frequencies (difference at 4 kHz = -4.25 dB HL) compared with population-based controls. CONCLUSION In the first study to use objectively measured hearing, FCD was associated with poorer low-frequency and better high-frequency audiometric thresholds than population controls. Further studies are needed to characterize this relationship.
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Affiliation(s)
- Nicholas S Reed
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD
- Center on Aging and Health, Johns Hopkins Medical Institutions, Baltimore, MD
| | - Jennifer A Deal
- Center on Aging and Health, Johns Hopkins Medical Institutions, Baltimore, MD
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | - Matthew G Huddle
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD
| | - Joshua F Betz
- Center on Aging and Health, Johns Hopkins Medical Institutions, Baltimore, MD
- Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | - Bethany E Bailey
- The Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD
| | - Elyse J McGlumphy
- The Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD
| | - Allen O Eghrari
- The Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD
| | - S Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD
| | - Frank R Lin
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD
- Center on Aging and Health, Johns Hopkins Medical Institutions, Baltimore, MD
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | - John D Gottsch
- The Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD
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36
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Alka K, Casey JR. Molecular phenotype of SLC4A11 missense mutants: Setting the stage for personalized medicine in corneal dystrophies. Hum Mutat 2018; 39:676-690. [PMID: 29327391 DOI: 10.1002/humu.23401] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 12/19/2017] [Accepted: 01/02/2018] [Indexed: 12/30/2022]
Abstract
SLC4A11 mutations cause cases of congenital hereditary endothelial dystrophy (CHED), Harboyan syndrome (HS), and Fuchs endothelial corneal dystrophy (FECD). Defective water reabsorption from corneal stroma by corneal endothelial cells (CECs) leads to these corneal dystrophies. SLC4A11, in the CEC basolateral membrane, facilitates transmembrane movement of H2 O, NH3 , and H+ -equivalents. Some SLC4A11 disease mutants have impaired folding, leading to a failure to move to the cell surface, which in some cases can be corrected by the drug, glafenine. To identify SLC4A11 mutants that are targets for folding-correction therapy, we examined 54 SLC4A11 missense mutants. Cell-surface trafficking was assessed on immunoblots, by the level of mature, high molecular weight, cell surface-associated form, and using a bioluminescence resonance energy transfer assay. Low level of cell surface trafficking was found in four out of 18 (20%) of FECD mutants, 19/ out of 31 (61%) of CHED mutants, and three out of five (60%) of HS mutants. Amongst ER-retained mutants, 16 showed increased plasma membrane trafficking when grown at 30°C, suggesting that their defect has potential for rescue. CHED-causing point mutations mostly resulted in folding defects, whereas the majority of FECD missense mutations did not affect trafficking, implying functional impairment. We identified mutations that make patients candidates for folding correction of their corneal dystrophy.
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Affiliation(s)
- Kumari Alka
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph R Casey
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
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Liu W, Tang FL, Lin S, Zhao K, Mei L, Ye J, Xiong WC. Vps35-deficiency impairs SLC4A11 trafficking and promotes corneal dystrophy. PLoS One 2017; 12:e0184906. [PMID: 28934248 PMCID: PMC5608277 DOI: 10.1371/journal.pone.0184906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/01/2017] [Indexed: 12/17/2022] Open
Abstract
Vps35 (vacuolar protein sorting 35) is a major component of retromer that selectively promotes endosome-to-Golgi retrieval of transmembrane proteins. Dysfunction of retromer is a risk factor for the pathogenesis of Parkinson’s disease (PD) and Alzheimer’s disease (AD). However, Vps35/retromer’s function in the eye or the contribution of Vps35-deficiency to eye degenerative disorders remains to be explored. Here we provide evidence for a critical role of Vps35 in mouse corneal dystrophy. Vps35 is expressed in mouse and human cornea. Mouse cornea from Vps35 heterozygotes (Vps35+/-) show features of dystrophy, such as loss of both endothelial and epithelial cell densities, disorganizations of endothelial, stroma, and epithelial cells, excrescences in the Descemet membrane, and corneal edema. Additionally, corneal epithelial cell proliferation was reduced in Vps35-deficient mice. Intriguingly, cell surface targeting of SLC4A11, a membrane transport protein (OH- /H+ /NH3 /H2O) of corneal endothelium, whose mutations have been identified in patients with corneal dystrophy, was impaired in Vps35-deficient cells and cornea. Taken together, these results suggest that SLC4A11 appears to be a Vps35/retromer cargo, and Vps35-regulation of SLC4A11 trafficking may underlie Vps35/retromer regulation of corneal dystrophy.
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Affiliation(s)
- Wei Liu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Ophthalmology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, China
| | - Fu-Lei Tang
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Sen Lin
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Ophthalmology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, China
| | - Kai Zhao
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Lin Mei
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Jian Ye
- Department of Ophthalmology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, China
- * E-mail: (WX); (JY)
| | - Wen-Cheng Xiong
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
- * E-mail: (WX); (JY)
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38
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Kumawat BL, Gupta R, Sharma A, Sen S, Gupta S, Tandon R. Delayed onset of congenital hereditary endothelial dystrophy due to compound heterozygous SLC4A11 mutations. Indian J Ophthalmol 2017; 64:492-5. [PMID: 27609159 PMCID: PMC5026072 DOI: 10.4103/0301-4738.190100] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background: Congenital hereditary endothelial dystrophy (CHED) is an autosomal recessive disorder characterized by bilateral, symmetrical, noninflammatory corneal clouding (edema) present at birth or shortly thereafter. This study reports on an unusual delayed presentation of CHED with compound heterozygous SLC4A11 mutations. Materials and Methods: A 45-year-old female, presenting with bilateral decreased vision since childhood that deteriorated in the last 5 years, was evaluated to rule out trauma, viral illness, chemical injury, glaucoma, and corneal endothelial dystrophies. Tear sample was sent for herpes simplex viral (HSV) antigen testing. Genomic DNA from peripheral blood was screened for mutations in all exons of SLC4A11 by direct sequencing. Full-thickness penetrating keratoplasty was done and corneal button was sent for histopathological examination. Results: Slit-lamp findings revealed bilateral diffuse corneal edema and left eye spheroidal degeneration with scarring. Increased corneal thickness (762 μm and 854 μm in the right and left eyes, respectively), normal intraocular pressure (12 mmHg and 16 mmHg in the right and left eyes, respectively), inconclusive confocal scan, and specular microscopy, near normal tear film parameters, were the other clinical features. HSV-polymerase chain reaction was negative. Histopathological examination revealed markedly thickened Descemet's membrane with subepithelial spheroidal degeneration. SLC4A11 screening showed a novel variant p.Ser415Asn, reported mutation p.Cys386Arg and two polymorphisms, all in the heterozygous state and not identified in 100 controls. Conclusions: The study shows, for the first time, compound heterozygous SLC4A11 mutations impair protein function leading to delayed onset of the disease.
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Affiliation(s)
- Babu Lal Kumawat
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Ranjan Gupta
- Department of Anatomy, Laboratory of Cyto-Molecular Genetics, All India Institute of Medical Sciences, New Delhi, India
| | - Arundhati Sharma
- Department of Anatomy, Laboratory of Cyto-Molecular Genetics, All India Institute of Medical Sciences, New Delhi, India
| | - Seema Sen
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Shikha Gupta
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Radhika Tandon
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
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39
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Zhang W, Ogando DG, Kim ET, Choi MJ, Li H, Tenessen JM, Bonanno JA. Conditionally Immortal Slc4a11-/- Mouse Corneal Endothelial Cell Line Recapitulates Disrupted Glutaminolysis Seen in Slc4a11-/- Mouse Model. Invest Ophthalmol Vis Sci 2017; 58:3723-3731. [PMID: 28738416 PMCID: PMC5525555 DOI: 10.1167/iovs.17-21781] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose To establish conditionally immortal mouse corneal endothelial cell lines with genetically matched Slc4a11+/+ and Slc4a11-/- mice as a model for investigating pathology and therapies for SLC4A11 associated congenital hereditary endothelial dystrophy (CHED) and Fuchs' endothelial corneal dystrophy. Methods We intercrossed H-2Kb-tsA58 mice (Immortomouse) expressing an IFN-γ dependent and temperature-sensitive mutant of the SV40 large T antigen (tsTAg) with Slc4a11+/+ and Slc4a11-/- C57BL/6 mice. The growth characteristics of the cell lines was assessed by doubling time. Ion transport activities (Na+/H+ exchange, bicarbonate, lactate, and Slc4a11 ammonia transport) were analyzed by intracellular pH measurement. The metabolic status of the cell lines was assessed by analyzing TCA cycle intermediates via gas chromatography mass spectrometry (GC-MS). Results The immortalized Slc4a11+/+ and Slc4a11-/- mouse corneal endothelial cells (MCECs) remained proliferative through passage 49 and maintained similar active ion transport activity. As expected, proliferation was temperature sensitive and IFN-γ dependent. Slc4a11-/- MCECs exhibited decreased proliferative capacity, reduced NH3:H+ transport, altered expression of glutaminolysis enzymes similar to the Slc4a11-/- mouse, and reduced proportion of TCA cycle intermediates derived from glutamine with compensatory increases in glucose flux compared with Slc4a11+/+ MCECs. Conclusions This is the first report of the immortalization of MCECs. Ion transport of the immortalized endothelial cells remains active, except for NH3:H+ transporter activity in Slc4a11-/- MCECs. Furthermore, Slc4a11-/- MCECs recapitulate the glutaminolysis defects observed in Slc4a11-/- mouse corneal endothelium, providing an excellent tool to study the pathogenesis of SLC4A11 mutations associated with corneal endothelial dystrophies and to screen potential therapeutic agents.
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Affiliation(s)
- Wenlin Zhang
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Diego G Ogando
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Edward T Kim
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Moon-Jung Choi
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Hongde Li
- Department of Biology, Indiana University, Bloomington, Indiana, United States
| | - Jason M Tenessen
- Department of Biology, Indiana University, Bloomington, Indiana, United States
| | - Joseph A Bonanno
- School of Optometry, Indiana University, Bloomington, Indiana, United States
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40
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Guha S, Chaurasia S, Ramachandran C, Roy S. SLC4A11 depletion impairs NRF2 mediated antioxidant signaling and increases reactive oxygen species in human corneal endothelial cells during oxidative stress. Sci Rep 2017. [PMID: 28642546 PMCID: PMC5481427 DOI: 10.1038/s41598-017-03654-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Corneal endothelial dystrophy is a progressive disease with gradual loss of vision and characterized by degeneration and dysfunction of corneal endothelial cells. Mutations in SLC4A11, a Na+ dependent OH− transporter, cause congenital hereditary endothelial dystrophy (CHED) and Fuchs’ endothelial corneal dystrophy (FECD), the two most common forms of endothelial degeneration. Along with genetic factors, oxidative stress plays a role in pathogenesis of several corneal diseases. In this study we looked into the role of SLC4A11 in antioxidant stress response in human corneal endothelial cells (HCEnC). We found increased expression of SLC4A11 in presence of oxidative stress. Depletion of SLC4A11 using targeted siRNA, caused an increase in reactive oxygen species, cytochrome c, lowered mitochondrial membrane potential, and reduced cell viability during oxidative stress. Moreover, SLC4A11 was found to be necessary for NRF2 mediated antioxidant gene expression in HCEnC. On the other hand, over expression of SLC4A11 reduces reactive oxygen species levels and increases cell viability. Lastly, CHED tissue specimens show evidence of oxidative stress and reduced expression of NRF2. In conclusion, our data suggests a possible role of SLC4A11 in regulating oxidative stress, and might be responsible for both the etiology and treatment of corneal endothelial dystrophy.
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Affiliation(s)
- Sanjukta Guha
- Prof. Brien Holden Eye Research Center, LVPEI, Hyderabad, India.,Research Scholar, Manipal University, Manipal, India
| | | | - Charanya Ramachandran
- Prof. Brien Holden Eye Research Center, LVPEI, Hyderabad, India.,Tej Kohli Cornea Institute, LVPEI, Hyderabad, India
| | - Sanhita Roy
- Prof. Brien Holden Eye Research Center, LVPEI, Hyderabad, India. .,Tej Kohli Cornea Institute, LVPEI, Hyderabad, India.
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41
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Badior KE, Alka K, Casey JR. SLC4A11 Three-Dimensional Homology Model Rationalizes Corneal Dystrophy-Causing Mutations. Hum Mutat 2016; 38:279-288. [PMID: 27925686 DOI: 10.1002/humu.23152] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 12/01/2016] [Indexed: 12/17/2022]
Abstract
We studied the structural effects of point mutations of a membrane protein that cause genetic disease. SLC4A11 is a membrane transport protein (OH- /H+ /NH3 /H2 O) of basolateral corneal endothelium, whose mutations cause some cases of congenital hereditary endothelial dystrophy and Fuchs endothelial corneal dystrophy. We created a three-dimensional homology model of SLC4A11 membrane domain, using Band 3 (SLC4A1) crystal structure as template. The homology model was assessed in silico and by analysis of mutants designed on the basis of the model. Catalytic pathway mutants p.Glu675Gln, p.His724Arg, and p.His724Ala impaired SLC4A11 transport. p.Ala720Leu, in a region of extended structure of the proposed translocation pore, failed to mature to the cell surface. p.Gly509Lys, located in an open region at the core domain/gate domain interface, had wild-type level of transport function. The molecular phenotype of 37 corneal dystrophy-causing point mutants was rationalized, based on their location in the homology model. Four map to the substrate translocation pathway, 25 to regions of close transmembrane helix packing, three to the dimeric interface, and five lie in extramembraneous loops. The model provides a view of the spectrum of effects of disease mutations on membrane protein structure and provides a tool to analyze pathogenicity of additional newly discovered SLC4A11 mutants.
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Affiliation(s)
- Katherine E Badior
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Kumari Alka
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph R Casey
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
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42
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Myers EJ, Marshall A, Jennings ML, Parker MD. Mouse Slc4a11 expressed in Xenopus oocytes is an ideally selective H+/OH- conductance pathway that is stimulated by rises in intracellular and extracellular pH. Am J Physiol Cell Physiol 2016; 311:C945-C959. [PMID: 27681179 PMCID: PMC5206308 DOI: 10.1152/ajpcell.00259.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 09/28/2016] [Indexed: 11/22/2022]
Abstract
The SLC4A11 gene encodes the bicarbonate-transporter-related protein BTR1, which is mutated in syndromes characterized by vision and hearing loss. Signs of these diseases [congenital hereditary endothelial dystrophy (CHED) and Harboyan syndrome] are evident in mouse models of Slc4a11 disruption. However, the intrinsic activity of Slc4a11 remains controversial, complicating assignment of its (patho)physiological role. Most studies concur that Slc4a11 transports H+ (or the thermodynamically equivalent species OH-) rather than HCO3-, but disparities have arisen as to whether the transport is coupled to another species such as Na+ or NH3/NH4+ Here for the first time, we examine the action of mouse Slc4a11 in Xenopus oocytes. We simultaneously monitor changes in intracellular pH, membrane potential, and conductance as we alter extracellular pH, revealing the electrical and chemical driving forces that underlie the observed ion fluxes. We find that mSlc4a11 is an ideally selective H+/OH- conductive pathway, the action of which is uncoupled from the cotransport of any other ion. We also find that the activity of mSlc4a11 is independently enhanced by both extracellular and intracellular alkalinization, suggesting OH- as the most likely substrate and providing a novel explanation for the apparent NH3-dependence of Slc4a11-mediated currents reported by others. We suggest that the unique properties of Slc4a11 action underlie its value as a pH regulator in corneal endothelial cells.
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Affiliation(s)
- Evan J Myers
- Department of Physiology and Biophysics, The State University of New York: The University at Buffalo, Buffalo, New York
| | - Aniko Marshall
- Department of Physiology and Biophysics, The State University of New York: The University at Buffalo, Buffalo, New York
| | - Michael L Jennings
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Mark D Parker
- Department of Physiology and Biophysics, The State University of New York: The University at Buffalo, Buffalo, New York;
- Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo: The State University of New York, Buffalo, New York; and
- State University of New York Eye Institutes, University at Buffalo: The State University of New York, Buffalo, New York
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43
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Kao L, Azimov R, Shao XM, Frausto RF, Abuladze N, Newman D, Aldave AJ, Kurtz I. Multifunctional ion transport properties of human SLC4A11: comparison of the SLC4A11-B and SLC4A11-C variants. Am J Physiol Cell Physiol 2016; 311:C820-C830. [PMID: 27581649 DOI: 10.1152/ajpcell.00233.2016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 08/30/2016] [Indexed: 12/13/2022]
Abstract
Congenital hereditary endothelial dystrophy (CHED), Harboyan syndrome (CHED with progressive sensorineural deafness), and potentially a subset of individuals with late-onset Fuchs' endothelial corneal dystrophy are caused by mutations in the SLC4A11 gene that results in corneal endothelial cell abnormalities. Originally classified as a borate transporter, the function of SLC4A11 as a transport protein remains poorly understood. Elucidating the transport function(s) of SLC4A11 is needed to better understand how its loss results in the aforementioned posterior corneal dystrophic disease processes. Quantitative PCR experiments demonstrated that, of the three known human NH2-terminal variants, SLC4A11-C is the major transcript expressed in human corneal endothelium. We studied the expression pattern of the three variants in mammalian HEK-293 cells and demonstrated that the SLC4A11-B and SLC4A11-C variants are plasma membrane proteins, whereas SLC4A11-A is localized intracellularly. SLC4A11-B and SLC4A11-C were shown to be multifunctional ion transporters capable of transporting H+ equivalents in both a Na+-independent and Na+-coupled mode. In both transport modes, SLC4A11-C H+ flux was significantly greater than SLC4A11-B. In the presence of ammonia, SLC4A11-B and SLC4A11-C generated inward currents that were comparable in magnitude. Chimera SLC4A11-C-NH2-terminus-SLC4A11-B experiments demonstrated that the SLC4A11-C NH2-terminus functions as an autoactivating domain, enhancing Na+-independent and Na+-coupled H+ flux without significantly affecting the electrogenic NH3-H(n)+ cotransport mode. All three modes of transport were significantly impaired in the presence of the CHED causing p.R109H (SLC4A11-C numbering) mutation. These complex ion transport properties need to be addressed in the context of corneal endothelial disease processes caused by mutations in SLC4A11.
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Affiliation(s)
- Liyo Kao
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Rustam Azimov
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Xuesi M Shao
- Department of Neurobiology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ricardo F Frausto
- Stein Eye Institute, and.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Natalia Abuladze
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Debra Newman
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Anthony J Aldave
- Stein Eye Institute, and.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ira Kurtz
- Division of Nephrology, .,Brain Research Institute.,David Geffen School of Medicine, University of California, Los Angeles, California
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44
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Loganathan SK, Schneider HP, Morgan PE, Deitmer JW, Casey JR. Functional assessment of SLC4A11, an integral membrane protein mutated in corneal dystrophies. Am J Physiol Cell Physiol 2016; 311:C735-C748. [PMID: 27558157 DOI: 10.1152/ajpcell.00078.2016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 08/17/2016] [Indexed: 12/19/2022]
Abstract
SLC4A11, a member of the SLC4 family of bicarbonate transporters, is a widely expressed integral membrane protein, abundant in kidney and cornea. Mutations of SLC4A11 cause some cases of the blinding corneal dystrophies, congenital hereditary endothelial dystrophy, and Fuchs endothelial corneal dystrophy. These diseases are marked by fluid accumulation in the corneal stroma, secondary to defective fluid reabsorption by the corneal endothelium. The role of SLC4A11 in these corneal dystrophies is not firmly established, as SLC4A11 function remains unclear. To clarify the normal function(s) of SLC4A11, we characterized the protein following expression in the simple, low-background expression system Xenopus laevis oocytes. Since plant and fungal SLC4A11 orthologs transport borate, we measured cell swelling associated with accumulation of solute borate. The plant water/borate transporter NIP5;1 manifested borate transport, whereas human SLC4A11 did not. SLC4A11 supported osmotically driven water accumulation that was electroneutral and Na+ independent. Studies in oocytes and HEK293 cells could not detect Na+-coupled HCO3- transport or Cl-/HCO3- exchange by SLC4A11. SLC4A11 mediated electroneutral NH3 transport in oocytes. Voltage-dependent OH- or H+ movement was not measurable in SLC4A11-expressing oocytes, but SLC4A11-expressing HEK293 cells manifested low-level cytosolic acidification at baseline. In mammalian cells, but not oocytes, OH-/H+ conductance may arise when SLC4A11 activates another protein or itself is activated by another protein. These data argue against a role of human SLC4A11 in bicarbonate or borate transport. This work provides additional support for water and ammonia transport by SLC4A11. When expressed in oocytes, SLC4A11 transported NH3, not NH3/H.
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Affiliation(s)
- Sampath K Loganathan
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Hans-Peter Schneider
- Abteilung für Allgemeine Zoologie, Fachbereich Biologie, Technische Universtät Kaiserslautern, Kaiserslautern, Germany; and
| | - Patricio E Morgan
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Joachim W Deitmer
- Abteilung für Allgemeine Zoologie, Fachbereich Biologie, Technische Universtät Kaiserslautern, Kaiserslautern, Germany; and
| | - Joseph R Casey
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada;
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45
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Hand CK, McGuire M, Parfrey NA, Murphy CC. Homozygous SLC4A11 mutation in a large Irish CHED2 pedigree. Ophthalmic Genet 2016; 38:148-151. [PMID: 27057589 DOI: 10.3109/13816810.2016.1151901] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Congenital hereditary endothelial dystrophy (CHED) is a genetic disorder of corneal endothelial cells resulting in corneal clouding and visual impairment. Autosomal dominant (CHED1) and autosomal recessive (CHED2) forms have been reported and map to distinct loci on chromosome 20. CHED2 is caused by mutations in the SLC4A11 gene which encodes a membrane transporter protein. MATERIALS AND METHODS Members of a large CHED2 family were recruited for clinical and genetic studies. Genomic DNA was sequenced for the exons and intron-exon boundaries of the SLC4A11 gene. RESULTS Twelve family members were recruited, of which eight were diagnosed with CHED. A homozygous SLC4A11 mutation (Leu843Pro) was detected in the eight patients; a single copy of the mutation was present in three unaffected carriers. CONCLUSIONS A missense SLC4A11 mutation (Leu843Pro) is responsible for CHED2 in this family; this is the first report of this mutation in a homozygous state.
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Affiliation(s)
- Collette K Hand
- a Department of Pathology , University College Cork , Cork , Ireland
| | - Mairide McGuire
- b Department of Ophthalmology , Royal Victoria Eye and Ear Hospital , Dublin , Ireland
| | - Nollaig A Parfrey
- a Department of Pathology , University College Cork , Cork , Ireland
| | - Conor C Murphy
- b Department of Ophthalmology , Royal Victoria Eye and Ear Hospital , Dublin , Ireland.,c Department of Ophthalmology , Royal College of Surgeons in Ireland , Dublin , Ireland
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Loganathan SK, Lukowski CM, Casey JR. The cytoplasmic domain is essential for transport function of the integral membrane transport protein SLC4A11. Am J Physiol Cell Physiol 2015; 310:C161-74. [PMID: 26582474 DOI: 10.1152/ajpcell.00246.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 11/11/2015] [Indexed: 12/21/2022]
Abstract
Large cytoplasmic domains (CD) are a common feature among integral membrane proteins. In virtually all cases, these CD have a function (e.g., binding cytoskeleton or regulatory factors) separate from that of the membrane domain (MD). Strong associations between CD and MD are rare. Here we studied SLC4A11, a membrane transport protein of corneal endothelial cells, the mutations of which cause genetic corneal blindness. SLC4A11 has a 41-kDa CD and a 57-kDa integral MD. One disease-causing mutation in the CD, R125H, manifests a catalytic defect, suggesting a role of the CD in transport function. Expressed in HEK-293 cells without the CD, MD-SLC4A11 is retained in the endoplasmic reticulum, indicating a folding defect. Replacement of CD-SLC4A11 with green fluorescent protein did not rescue MD-SLC4A11, suggesting some specific role of CD-SLC4A11. Homology modeling revealed that the structure of CD-SLC4A11 is similar to that of the Cl(-)/HCO3(-) exchange protein AE1 (SLC4A1) CD. Fusion to CD-AE1 partially rescued MD-SLC4A11 to the cell surface, suggesting that the structure of CD-AE1 is similar to that of CD-SLC4A11. The CD-AE1-MD-SLC4a11 chimera, however, had no functional activity. We conclude that CD-SLC4A11 has an indispensable role in the transport function of SLC4A11. CD-SLC4A11 forms insoluble precipitates when expressed in bacteria, suggesting that the domain cannot fold properly when expressed alone. Consistent with a strong association between CD-SLC4A11 and MD-SLC4A11, these domains specifically associate when coexpressed in HEK-293 cells. We conclude that SLC4A11 is a rare integral membrane protein in which the CD has strong associations with the integral MD, which contributes to membrane transport function.
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Affiliation(s)
- Sampath K Loganathan
- Membrane Protein Disease Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Chris M Lukowski
- Membrane Protein Disease Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph R Casey
- Membrane Protein Disease Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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SLC4A11 and the Pathophysiology of Congenital Hereditary Endothelial Dystrophy. BIOMED RESEARCH INTERNATIONAL 2015; 2015:475392. [PMID: 26451371 PMCID: PMC4588344 DOI: 10.1155/2015/475392] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 05/17/2015] [Indexed: 12/13/2022]
Abstract
Congenital hereditary endothelial dystrophy (CHED) is a rare autosomal recessive disorder of the corneal endothelium characterized by nonprogressive bilateral corneal edema and opacification present at birth. Here we review the current knowledge on the role of the SLC4A11 gene, protein, and its mutations in the pathophysiology and clinical presentation of CHED. Individuals with CHED have mutations in SLC4A11 which encodes a transmembrane protein in the SLC4 family of bicarbonate transporters. The expression of SLC4A11 in the corneal endothelium and inner ear patterns the deficits seen in CHED with corneal edema and hearing loss (Harboyan syndrome). slc4a11-null-mouse models recapitulate the CHED disease phenotype, thus establishing a functional role for SLC4A11 in CHED. However, the transport function of SLC4A11 remains unsettled. Some of the roles that have been attributed to SLC4A11 include H(+) and NH4 (+) permeation, electrogenic Na(+)-H(+) exchange, and water transport. Future studies of the consequences of SLC4A11 dysfunction as well as further understanding of corneal endothelial ion transport will help clarify the involvement of SLC4A11 in the pathophysiology of CHED.
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Mutations in the Corneal Endothelial Dystrophy–Associated Gene SLC4A11 Render the Cells More Vulnerable to Oxidative Insults. Cornea 2015; 34:668-74. [DOI: 10.1097/ico.0000000000000421] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Jalimarada SS, Ogando DG, Bonanno JA. Loss of ion transporters and increased unfolded protein response in Fuchs' dystrophy. Mol Vis 2014; 20:1668-79. [PMID: 25548511 PMCID: PMC4265779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 12/09/2014] [Indexed: 11/30/2022] Open
Abstract
PURPOSE Fuchs' endothelial corneal dystrophy (FECD), which affects approximately 5% of the population over 40 in the U.S.A., is a major cause of corneal transplantation. FECD is associated with mutations of a variety of unrelated genes: SLC4A11, COL8A2, TCF8, and LOXHD1. The current pathological description of the dystrophy includes deficiency of corneal endothelium (CE) pump function and induction of the unfolded protein response (UPR). This study aims to determine the contribution of the two mechanisms by assessing the expression levels of (1) seven endothelial ion transporters known to regulate stromal hydration and (2) UPR related genes in a set of six CE samples obtained from FECD patients compared to that of normal controls. METHODS CE samples collected during FECD keratoplasty or from an eye bank (normal control) were transferred into an RNA stabilizing agent and refrigerated. Total RNA from each CE specimen was individually extracted. The expression levels of ion transporters and UPR genes were tested using quantitative real-time (RT) PCR and a UPR specific PCR array, respectively. RESULTS In normal CE, the comparative expression levels of ion transporters in decreasing order were SLC4A11, Na(+)/K(+) ATPase, pNBCe1, and NHE1, followed by the isoforms of monocarboxylate transporters (MCTs). In FECD samples, Na(+)/K(+) ATPase and MCTs 1 and 4 were significantly downregulated compared to normal controls (p<0.05). The PCR array tested 84 UPR related genes. Data analysis showed upregulation of 39 genes and downregulation of three genes, i.e., approximately 51% of the tested genes had their expression altered in FECD samples with a difference greater than ± twofold regulation. Thirteen of the altered genes showed significant changes (p<0.05). The PCR array results were validated by quantitative RT-PCR. CONCLUSIONS FECD samples had evident UPR with significant changes in the expression of the protein processing pathway genes. The significant downregulation of ion transporters indicates simultaneous compromised CE pump function in Fuchs' dystrophy.
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Liskova P, Dudakova L, Tesar V, Bednarova V, Kidorova J, Jirsova K, Davidson AE, Hardcastle AJ. Detailed assessment of renal function in a proband with Harboyan syndrome caused by a novel homozygous SLC4A11 nonsense mutation. Ophthalmic Res 2014; 53:30-5. [PMID: 25500497 DOI: 10.1159/000365109] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 05/28/2014] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS To identify the underlying molecular genetic cause of disease in a patient with Harboyan syndrome and to perform a detailed assessment of her renal function. We also assessed the influence of the SLC4A11 mutation identified on the corneal endothelium in the heterozygous state. METHODS A 55-year-old female was examined ophthalmologically, audiologically and nephrologically including 24-hour urine collection. The coding region of SLC4A11 was directly sequenced. Specular microscopy was performed in the proband's 21-year-old daughter. RESULTS The proband had bilateral iridectomy at the age of 3 months because of an initial diagnosis of congenital glaucoma and since the age of 12 years she underwent several keratoplasties in each eye. Nephrological examination did not reveal any abnormalities. Moderate bilateral sensorineural hearing loss was confirmed by audiometry. A novel homozygous mutation predicted to lead to a premature stop codon at the protein level, c.2188C>T; p.(Arg730*), was identified in SLC4A11. No changes in corneal endothelial cell morphology or density were observed in the heterozygous daughter. CONCLUSION In contrast to the Slc4a11(-/-) mouse, no abnormalities in daily renal ion excretion or polyuria were observed in the Harboyan syndrome patient. The mutation identified does not affect corneal endothelial cell morphology or density in the heterozygous state.
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Affiliation(s)
- Petra Liskova
- Laboratory of the Biology and Pathology of the Eye, Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
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