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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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Brunner BS, Kassumeh S, Rudolph G, Priglinger SG, Messmer EM. [Corneal disease in childhood-Hereditary, degenerative or infectious?]. DIE OPHTHALMOLOGIE 2023; 120:811-817. [PMID: 37438454 DOI: 10.1007/s00347-023-01897-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/25/2023] [Accepted: 06/26/2023] [Indexed: 07/14/2023]
Abstract
BACKGROUND Adequate visual acuity significantly contributes to the age-appropriate development of children's neurobehavior. Infantile corneal opacities are rare but implicate a high potential for amblyopia. OBJECTIVE This review aims to provide an overview of the most common causes of infantile corneal opacities and highlights ophthalmopathological correlations. METHODS The following review is based on an extensive literature search. RESULTS If metabolic diseases, traumatic or infectious events can be excluded as a cause for an infantile corneal opacity, it is important to focus on the 3Ds, corneal dysgenesis, corneal dystrophy or corneal degeneration. DISCUSSION If corneal opacities occur in childhood, early recognition, diagnosis, and initiation of treatment, including prophylaxis of amblyopia, are of utmost importance. In unexplained corneal opacities the histopathological work-up of the explanted cornea can contribute to the final diagnosis.
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Affiliation(s)
- Barbara S Brunner
- Augenklinik und Poliklinik, Klinikum der Universität München, LMU München, Mathildenstr. 8, 80336, München, Deutschland
| | - Stefan Kassumeh
- Augenklinik und Poliklinik, Klinikum der Universität München, LMU München, Mathildenstr. 8, 80336, München, Deutschland
| | - Günter Rudolph
- Augenklinik und Poliklinik, Klinikum der Universität München, LMU München, Mathildenstr. 8, 80336, München, Deutschland
| | - Siegfried G Priglinger
- Augenklinik und Poliklinik, Klinikum der Universität München, LMU München, Mathildenstr. 8, 80336, München, Deutschland
| | - Elisabeth M Messmer
- Augenklinik und Poliklinik, Klinikum der Universität München, LMU München, Mathildenstr. 8, 80336, München, Deutschland.
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Abstract
PURPOSE Congenital hereditary endothelial dystrophy (CHED) is a rare, autosomal recessive, monogenic corneal condition with variable expressivity. Often presents in bilateral symmetrical progressive corneal cloudiness that starts in the early infancy. It is characterized by increased corneal thickness, profound corneal edema, and thickening of the Descemet membrane due to endothelial dysfunction. The published literature lacks uniform guidelines for grading corneal cloudiness and management algorithm for CHED cases. This article focuses on applying newer investigational modalities to fine-tune surgical outcomes and more recent CHED management strategies. METHODS This comprehensive literature review was performed based on a search on the PubMed database of relevant CHED articles focusing on those published in the last 7 years. A total of around 70 articles were reviewed, and 17 of them were included in this review. These include systemic reviews, randomized controlled clinical trials, cohort studies, case-controlled studies, and case series. RESULTS Corneal cloudiness grading in CHED using subjective and objective methods using Anterior Segment Optical Coherence Tomography (AS-OCT) and densitometry using Scheimpflug imaging can help select appropriate management plan for CHED cases. DSAEK outscores penetrating keratoplasty with much fewer complications and expedites visual recovery, which helps mitigate amblyopia. CONCLUSION Managing cases of CHED has been a challenge due to the dilemma in timing and appropriate surgical method selection and lack of definitive medical or other conservative approaches. Currently, DSAEK has shown favorable results in cases of CHED. However, appropriate staging of CHED and selecting the appropriate management approach appears to play a critical role in managing such cases. Besides these, novel treatment modalities such as nonsteroidal anti-inflammatory agents (NSAIDS) that target restoring water-flux activity in subtype of CHED and gene editing using CRISPR-Cas9 are promising paradigm treatment modalities.
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Affiliation(s)
- Neet Mehta
- Academy of Eye Care Education, L V Prasad Eye Institute, Hyderabad, India
| | - Muralidhar Ramappa
- Centre for Rare Eye Diseases and Ocular Genetics, L V Prasad Eye Institute, Hyderabad, India.,The Cornea Institute, L V Prasad Eye Institute, Hyderabad, India.,Ramanamma Children's Eye Care Center, L V Prasad Eye InstituteJasti V , Hyderabad, India
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Kato A, Kimura Y, Kurita Y, Chang MH, Kasai K, Fujiwara T, Hirata T, Doi H, Hirose S, Romero MF. Seawater fish use an electrogenic boric acid transporter, Slc4a11A, for boric acid excretion by the kidney. J Biol Chem 2023; 299:102740. [PMID: 36435196 PMCID: PMC9803922 DOI: 10.1016/j.jbc.2022.102740] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 11/20/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022] Open
Abstract
Boric acid is a vital micronutrient in animals; however, excess amounts are toxic to them. Little is known about whole-body boric acid homeostasis in animals. Seawater (SW) contains 0.4 mM boric acid, and since marine fish drink SW, their urinary system was used here as a model of the boric acid excretion system. We determined that the bladder urine of a euryhaline pufferfish (river pufferfish, Takifugu obscurus) acclimated to fresh water and SW contained 0.020 and 19 mM of boric acid, respectively (a 950-fold difference), indicating the presence of a powerful excretory renal system for boric acid. Slc4a11 is a potential animal homolog of the plant boron transporter BOR1; however, mammalian Slc4a11 mediates H+ (OH-) conductance but does not transport boric acid. We found that renal expression of the pufferfish paralog of Slc4a11, Slc4a11A, was markedly induced after transfer from fresh water to SW, and Slc4a11A was localized to the apical membrane of kidney tubules. When pufferfish Slc4a11A was expressed in Xenopus oocytes, exposure to media containing boric acid and a voltage clamp elicited whole-cell outward currents, a marked increase in pHi, and increased boron content. In addition, the activity of Slc4a11A was independent of extracellular Na+. These results indicate that pufferfish Slc4a11A is an electrogenic boric acid transporter that functions as a B(OH)4- uniporter, B(OH)3-OH- cotransporter, or B(OH)3/H+ exchanger. These observations suggest that Slc4a11A is involved in the kidney tubular secretion of boric acid in SW fish, probably induced by the negative membrane potential and low pH of urine.
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Affiliation(s)
- Akira Kato
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan; Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan; Center for Biological Resources and Informatics, Tokyo Institute of Technology, Yokohama, Japan; Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.
| | - Yuuri Kimura
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
| | - Yukihiro Kurita
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
| | - Min-Hwang Chang
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Koji Kasai
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Toru Fujiwara
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Taku Hirata
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Hiroyuki Doi
- Nifrel, Osaka Aquarium Kaiyukan Co, Ltd, Osaka, Japan
| | - Shigehisa Hirose
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA; Nephrology & Hypertension, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA; O'Brien Urology Research Center, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.
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Rauniyar D, Das AV. Consanguinity and ocular disorders in India: Electronic medical records driven big data analytics. Indian J Ophthalmol 2022; 70:2401-2407. [PMID: 35791120 PMCID: PMC9426102 DOI: 10.4103/ijo.ijo_1553_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Purpose: To describe the distribution of ocular disorders in patients with a family history of consanguinity presenting to a multi-tier ophthalmology hospital network in India. Methods: This cross-sectional hospital-based study included 2,805,267 new patients presenting between August 2010 and April 2021. Patients with a family history of consanguinity were included as cases. The sociodemographic and clinical data were collected using an electronic medical record system. Results: Overall, 20,445 (0.73%) new patients were documented to have a family history of consanguinity. The prevalence rates were 4.04% in children (age: <16 years) and 0.21% in adults. The mean age of the patients was 11.87 ± 11.06 years. The majority of the patients were males (56.48%) and students (54.43%) by profession. The majority (93.05%) of the patients were in the 0–30-years age bracket, with over half of them (53.71%) presenting in the first decade of life. A significant number of patients were from higher socioeconomic status (73.48%) and the rural region (47.62%). The most common degree of consanguinity documented was second degree (3.95%). The most common ocular disorders associated with a high proportion of consanguinity were congenital hereditary endothelial dystrophy (CHED) (100%), corneal macular dystrophy (83.78%), xeroderma pigmentosum (80.95%), and ocular albinism (73.59%). A tenth of the patients (9.8%) reported a similar history of ocular disorders among the family members and more commonly among the siblings (70.4%). Conclusion: Consanguineous marriages are not uncommon in India. They cause ocular disorders that cause visual impairment in a significant majority of those affected in their early decades of life. Genetic counseling plays a role in prevention.
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Affiliation(s)
- Divya Rauniyar
- Bausch and Lomb School of Optometry, L. V. Prasad Eye Institute, Hyderabad, Telangana, India
| | - Anthony Vipin Das
- Department of eyeSmart EMR and AEye; Indian Health Outcomes, Public Health and Economics Research Center, L. V. Prasad Eye Institute, Hyderabad, Telangana, India
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Bonanno JA, Shyam R, Choi M, Ogando DG. The H + Transporter SLC4A11: Roles in Metabolism, Oxidative Stress and Mitochondrial Uncoupling. Cells 2022; 11:197. [PMID: 35053313 PMCID: PMC8773465 DOI: 10.3390/cells11020197] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/03/2022] [Accepted: 01/05/2022] [Indexed: 12/23/2022] Open
Abstract
Solute-linked cotransporter, SLC4A11, a member of the bicarbonate transporter family, is an electrogenic H+ transporter activated by NH3 and alkaline pH. Although SLC4A11 does not transport bicarbonate, it shares many properties with other members of the SLC4 family. SLC4A11 mutations can lead to corneal endothelial dystrophy and hearing deficits that are recapitulated in SLC4A11 knock-out mice. SLC4A11, at the inner mitochondrial membrane, facilitates glutamine catabolism and suppresses the production of mitochondrial superoxide by providing ammonia-sensitive H+ uncoupling that reduces glutamine-driven mitochondrial membrane potential hyperpolarization. Mitochondrial oxidative stress in SLC4A11 KO also triggers dysfunctional autophagy and lysosomes, as well as ER stress. SLC4A11 expression is induced by oxidative stress through the transcription factor NRF2, the master regulator of antioxidant genes. Outside of the corneal endothelium, SLC4A11's function has been demonstrated in cochlear fibrocytes, salivary glands, and kidneys, but is largely unexplored overall. Increased SLC4A11 expression is a component of some "glutamine-addicted" cancers, and is possibly linked to cells and tissues that rely on glutamine catabolism.
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Affiliation(s)
- Joseph A. Bonanno
- Vision Science Program, School of Optometry, Indiana University, Bloomington, IN 47405, USA; (R.S.); (M.C.).; (D.G.O.)
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Overview of Congenital Corneal Opacities: Clinical Diagnosis, Treatment, and Prognosis. Int Ophthalmol Clin 2022; 62:1-13. [PMID: 34965222 DOI: 10.1097/iio.0000000000000395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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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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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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Guha S, Roy S. Enhanced expression of SLC4A11 by tert-Butylhydroquinone is mediated by direct binding of Nrf2 to the promoter of SLC4A11. Free Radic Biol Med 2021; 167:299-306. [PMID: 33744340 DOI: 10.1016/j.freeradbiomed.2021.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/04/2021] [Accepted: 03/05/2021] [Indexed: 11/16/2022]
Abstract
BACKGROUND SLC4A11, a Na + dependent OH- transporter, is highly expressed in the epithelium and endothelium of the cornea. Mutations in SLC4A11 cause congenital hereditary endothelial dystrophy (CHED), a progressive disease with gradual loss of vision and characterized by degeneration and dysfunction of corneal endothelial cells. SLC4A11 expression is also responsive to oxidative stress. Thus, understanding of SLC4A11 gene regulation is of utmost importance for therapeutic interventions. However, it remains elusive how SLC4A11 is regulated at transcriptional and translational level. METHODS Bioinformatics analysis of the SLC4A11 promoter was performed using TRANSFAC. SLC4A11 promoter constructs were generated and exposed to tert-Butylhydroquinone (tBHQ) or cotransfected with Nuclear factor erythroid 2-related factor 2 (Nrf2) expression plasmid and promoter activity was determined. The expression of SLC4A11 was also determined by quantitative PCR and immunoblot analysis. The binding of Nrf2 to the promoter of SLC4A11 was validated by chromatin immunoprecipitation assay. RESULTS Induction of Nrf2 by tBHQ or overexpression of Nrf2 caused increased expression of SLC4A11 in HeLa and human corneal endothelial cells. A conserved Nrf2 binding sequence was found in the promoter of SLC4A11 of several mammalian species. Reporter gene assays showed transcriptional activation of the SLC4A11 promoter in response to tBHQ treatment and Nrf2 overexpression. ChIP analysis validated Nrf2 binding to the conserved sequence of the SLC4A11 promoter. Induction of the Nrf2 pathway also resulted in increased endogenous SLC4A11 protein abundance. On the other hand, depletion of Nrf2 inhibited both transcriptional and translational activities of SLC4A11. CONCLUSION In summary, we determined direct Nrf2 binding to antioxidant responsive element site within the SLC4A11 promoter, and observed increased expression of SLC4A11 by Nrf2 inducers. To the best of our knowledge, this is the first study showing Nrf2 exerts an important role in regulation of SLC4A11 gene expression.
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Affiliation(s)
- Sanjukta Guha
- Prof. Brien Holden Eye Research Centre, LV Prasad Eye Institute, Hyderabad, India; Manipal Academy of Higher Education, Manipal, India
| | - Sanhita Roy
- Prof. Brien Holden Eye Research Centre, LV Prasad Eye Institute, Hyderabad, India.
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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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Quade BN, Parker MD, Occhipinti R. The therapeutic importance of acid-base balance. Biochem Pharmacol 2021; 183:114278. [PMID: 33039418 PMCID: PMC7544731 DOI: 10.1016/j.bcp.2020.114278] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 10/06/2020] [Indexed: 02/06/2023]
Abstract
Baking soda and vinegar have been used as home remedies for generations and today we are only a mouse-click away from claims that baking soda, lemon juice, and apple cider vinegar are miracles cures for everything from cancer to COVID-19. Despite these specious claims, the therapeutic value of controlling acid-base balance is indisputable and is the basis of Food and Drug Administration-approved treatments for constipation, epilepsy, metabolic acidosis, and peptic ulcers. In this narrative review, we present evidence in support of the current and potential therapeutic value of countering local and systemic acid-base imbalances, several of which do in fact involve the administration of baking soda (sodium bicarbonate). Furthermore, we discuss the side effects of pharmaceuticals on acid-base balance as well as the influence of acid-base status on the pharmacokinetic properties of drugs. Our review considers all major organ systems as well as information relevant to several clinical specialties such as anesthesiology, infectious disease, oncology, dentistry, and surgery.
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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, NY 14203, USA
| | - Mark D Parker
- Department of Physiology and Biophysics, The State University of New York, The University at Buffalo, Buffalo, NY 14203, USA; Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA; State University of New York Eye Institute, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Rossana Occhipinti
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA.
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Tananuvat N, Tananuvat R, Chartapisak W, Mahanupab P, Hokierti C, Srikummool M, Kampuansai J, Intachai W, Olsen B, Ketudat Cairns JR, Kantaputra P. Harboyan syndrome: novel SLC4A11 mutation, clinical manifestations, and outcome of corneal transplantation. J Hum Genet 2020; 66:193-203. [PMID: 32884076 DOI: 10.1038/s10038-020-00834-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/20/2020] [Accepted: 08/27/2020] [Indexed: 11/10/2022]
Abstract
Harboyan syndrome or corneal dystrophy and progressive deafness (MIM #217400) is characterized by congenital hereditary endothelial dystrophy (CHED) and progressive, sensorineural hearing loss. Mutations in SLC4A11 are responsible for this rare genetic syndrome. Eight patients from seven unrelated families affected with Harboyan Syndrome with mean follow-up of 12.0 ± 0.9 years were thoroughly investigated for the ocular, hearing, and kidney function abnormalities and the outcome of penetrating keratoplasty (PK). Mutation analysis of SLC4A11 was performed. All patients presented with bilateral cloudy corneas since birth. Sensorineural hearing loss was detected in all patients. Seven patients (11 eyes) underwent PK with the median age at surgery of 10.1 years (7.1-22.9). The overall corneal graft survival rate after primary PK was 72.7% (8/11 eyes). The mean graft survival time was 94.6 months (95% CI 83.1-126.0). All patients had unremarkable kidney function. The c.2264G>A (p.Arg755Gln) mutation in SCL4A11 was detected in most patients (87.5%). All unrelated Karen tribe patients had p.Arg755Gln mutation, suggestive of founder effect. We found the allele frequency of this variant in the Karen population to be 0.01. The c.2263C>T (p.Arg755Trp) mutation was found in one patient with mild phenotype and the novel truncating protein mutation c.2127delG (p.Gly710fsx*25) in SCL4A11 was identified in two Thai sisters. Visual outcome and graft survival after PK were satisfactory. Our study shows that all studied patients with SLC4A11 mutations had CHED and sensorineural hearing loss, and SLC4A11 mutations were not related to the onset and severity of hearing loss or outcome of keratoplasty.
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Affiliation(s)
- Napaporn Tananuvat
- Department of Ophthalmology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Rak Tananuvat
- Department of Otolaryngology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Wattana Chartapisak
- Department of Pediatrics, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Pongsak Mahanupab
- Department of Pathology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | | | - Metawee Srikummool
- Department of Biochemistry, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Jatupol Kampuansai
- Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand
| | - Worrachet Intachai
- Center of Excellence in Medical Genetics Research, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand
| | - Bjorn Olsen
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
| | - James R Ketudat Cairns
- School of Chemistry, Institute of Science, and Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima, Thailand.,Laboratory of Biochemistry, Chulabhorn Research Institute, Bangkok, Thailand
| | - Piranit Kantaputra
- Division of Pediatric Dentistry, Department of Orthodontics and Pediatric Dentistry, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
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14
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Eintracht J, Toms M, Moosajee M. The Use of Induced Pluripotent Stem Cells as a Model for Developmental Eye Disorders. Front Cell Neurosci 2020; 14:265. [PMID: 32973457 PMCID: PMC7468397 DOI: 10.3389/fncel.2020.00265] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 07/28/2020] [Indexed: 12/15/2022] Open
Abstract
Approximately one-third of childhood blindness is attributed to developmental eye disorders, of which 80% have a genetic cause. Eye morphogenesis is tightly regulated by a highly conserved network of transcription factors when disrupted by genetic mutations can result in severe ocular malformation. Human-induced pluripotent stem cells (hiPSCs) are an attractive tool to study early eye development as they are more physiologically relevant than animal models, can be patient-specific and their use does not elicit the ethical concerns associated with human embryonic stem cells. The generation of self-organizing hiPSC-derived optic cups is a major advancement to understanding mechanisms of ocular development and disease. Their development in vitro has been found to mirror that of the human eye and these early organoids have been used to effectively model microphthalmia caused by a VSX2 variant. hiPSC-derived optic cups, retina, and cornea organoids are powerful tools for future modeling of disease phenotypes and will enable a greater understanding of the pathophysiology of many other developmental eye disorders. These models will also provide an effective platform for identifying molecular therapeutic targets and for future clinical applications.
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Affiliation(s)
| | - Maria Toms
- UCL Institute of Ophthalmology, London, United Kingdom.,The Francis Crick Institute, London, United Kingdom
| | - Mariya Moosajee
- UCL Institute of Ophthalmology, London, United Kingdom.,The Francis Crick Institute, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.,Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
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15
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Soh YQ, Kocaba V, Weiss JS, Jurkunas UV, Kinoshita S, Aldave AJ, Mehta JS. Corneal dystrophies. Nat Rev Dis Primers 2020; 6:46. [PMID: 32528047 DOI: 10.1038/s41572-020-0178-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/24/2020] [Indexed: 12/21/2022]
Abstract
Corneal dystrophies are broadly defined as inherited disorders that affect any layer of the cornea and are usually progressive, bilateral conditions that do not have systemic effects. The 2015 International Classification of Corneal Dystrophies classifies corneal dystrophies into four classes: epithelial and subepithelial dystrophies, epithelial-stromal TGFBI dystrophies, stromal dystrophies and endothelial dystrophies. Whereas some corneal dystrophies may result in few or mild symptoms and morbidity throughout a patient's lifetime, others may progress and eventually result in substantial visual and ocular disturbances that require medical or surgical intervention. Corneal transplantation, either with full-thickness or partial-thickness donor tissue, may be indicated for patients with advanced corneal dystrophies. Although corneal transplantation techniques have improved considerably over the past two decades, these surgeries are still associated with postoperative risks of disease recurrence, graft failure and other complications that may result in blindness. In addition, a global shortage of cadaveric corneal graft tissue critically limits accessibility to corneal transplantation in some parts of the world. Ongoing advances in gene therapy, regenerative therapy and cell augmentation therapy may eventually result in the development of alternative, novel treatments for corneal dystrophies, which may substantially improve the quality of life of patients with these disorders.
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Affiliation(s)
- Yu Qiang Soh
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore, Singapore.,Singapore National Eye Centre, Singapore, Singapore.,Ophthalmology Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore, Singapore.,Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Viridiana Kocaba
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore, Singapore.,Netherlands Institute for Innovative Ocular Surgery, Rotterdam, Netherlands
| | - Jayne S Weiss
- Department of Ophthalmology, Pathology and Pharmacology, Louisiana State University, School of Medicine, New Orleans, USA
| | - Ula V Jurkunas
- Cornea and Refractive Surgery Service, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA.,Schepens Eye Research Institute, Boston, Massachusetts, USA.,Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Shigeru Kinoshita
- Department of Frontier Medical Science and Technology for Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Anthony J Aldave
- Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Jodhbir S Mehta
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore, Singapore. .,Singapore National Eye Centre, Singapore, Singapore. .,Ophthalmology Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore, Singapore. .,Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore, Singapore.
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16
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Malhotra D, Casey JR. Molecular Mechanisms of Fuchs and Congenital Hereditary Endothelial Corneal Dystrophies. Rev Physiol Biochem Pharmacol 2020; 178:41-81. [PMID: 32789790 DOI: 10.1007/112_2020_39] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cornea, the eye's outermost layer, protects the eye from the environment. The cornea's innermost layer is an endothelium separating the stromal layer from the aqueous humor. A central role of the endothelium is to maintain stromal hydration state. Defects in maintaining this hydration can impair corneal clarity and thus visual acuity. Two endothelial corneal dystrophies, Fuchs Endothelial Corneal Dystrophy (FECD) and Congenital Hereditary Endothelial Dystrophy (CHED), are blinding corneal diseases with varied clinical presentation in patients across different age demographics. Recessive CHED with an early onset (typically age: 0-3 years) and dominantly inherited FECD with a late onset (age: 40-50 years) have similar phenotypes, although caused by defects in several different genes. A range of molecular mechanisms have been proposed to explain FECD and CHED pathology given the involvement of multiple causative genes. This critical review provides insight into the proposed molecular mechanisms underlying FECD and CHED pathology along with common pathways that may explain the link between the defective gene products and provide a new perspective to view these genetic blinding diseases.
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Affiliation(s)
- Darpan Malhotra
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB, Canada
| | - Joseph R Casey
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB, Canada.
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.
- Department of Ophthalmology and Visual Science, University of Alberta, Edmonton, AB, Canada.
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17
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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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18
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Yang N, Mukaibo T, Gao X, Kurtz I, Melvin JE. Slc4a11 disruption causes duct cell loss and impairs NaCl reabsorption in female mouse submandibular glands. Physiol Rep 2019; 7:e14232. [PMID: 31833218 PMCID: PMC6908739 DOI: 10.14814/phy2.14232] [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: 06/17/2019] [Revised: 08/19/2019] [Accepted: 08/20/2019] [Indexed: 12/11/2022] Open
Abstract
Slc4a11, a member of the Slc4 HCO3- transporter family, has a wide tissue distribution. In mouse salivary glands, the expression of Slc4a11 mRNA was more than eightfold greater than the other nine members of the Slc4 gene family. The Slc4a11 protein displayed a diffuse subcellular distribution in both the acinar and duct cells of mouse submandibular glands (SMG). Slc4a11 disruption induced a significant increase in the Na+ and Cl- concentrations of stimulated SMG saliva, whereas it did not affect the fluid secretion rate in response to either β-adrenergic or cholinergic receptor stimulation. Heterologous expressed mouse Slc4a11 acted as a H+ /OH- transporter that was uncoupled of Na+ or Cl- movement, and this activity was blocked by ethyl-isopropyl amiloride (EIPA) but not 4,4'-Diisothiocyanato-2,2'-stilbenedisulfonic acid (DIDS). Slc4a11 disruption revealed that Slc4a11 does not play a major role in intracellular pH regulation in mouse salivary gland cells. In contrast, NaCl reabsorption was impaired in the SMG saliva of female compared to male Slc4a11 null mice, which correlated with the loss of duct cells and a decrease in expression of the duct-cell-specific transcription factor Ascl3. Together, our results suggest that Slc4a11 expression regulates the number of ducts cells in the mouse SMG and consequently NaCl reabsorption.
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Affiliation(s)
- Ning‐Yan Yang
- Secretory Mechanisms and Dysfunctions SectionNational Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMaryland
- Department of Pediatric DentistryBeijing Stomatological Hospital & School of StomatologyCapital Medical UniversityBeijingChina
| | - Taro Mukaibo
- Secretory Mechanisms and Dysfunctions SectionNational Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMaryland
- Division of Oral Reconstruction and RehabilitationKyushu Dental UniversityKitakyushuFukuokaJapan
| | - Xin Gao
- Secretory Mechanisms and Dysfunctions SectionNational Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMaryland
| | - Ira Kurtz
- Department of MedicineDivision of NephrologyDavid Geffen School of Medicine, and the Brain Research InstituteUniversity of CaliforniaLos AngelesCalifornia
| | - James E. Melvin
- Secretory Mechanisms and Dysfunctions SectionNational Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMaryland
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19
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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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20
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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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21
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Angmo D, Selvan H, Behera A, Suman P. Response to comment on ‘Unilateral corneal edema in young: A diagnostic dilemma’. Indian J Ophthalmol 2019; 67:442-443. [PMID: 30777985 PMCID: PMC6407402 DOI: 10.4103/ijo.ijo_2079_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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22
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Angmo D, Selvan H, Behera AK, Suman PK. Unilateral corneal edema in young: A diagnostic dilemma. Indian J Ophthalmol 2018; 66:1612-1614. [PMID: 30355874 PMCID: PMC6213689 DOI: 10.4103/ijo.ijo_564_18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Dewang Angmo
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Harathy Selvan
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Aswini Kumar Behera
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Pramod Kumar Suman
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
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23
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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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24
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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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AlArrayedh H, Collum L, Murphy CC. Outcomes of penetrating keratoplasty in congenital hereditary endothelial dystrophy. Br J Ophthalmol 2017; 102:19-25. [DOI: 10.1136/bjophthalmol-2016-309565] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 03/20/2017] [Accepted: 04/02/2017] [Indexed: 11/04/2022]
Abstract
Background/aimTo report the outcome of penetrating keratoplasty (PKP) in Irish patients with congenital hereditary endothelial dystrophy (CHED).MethodsA retrospective case series review of patients with CHED who underwent PKP was conducted. The outcomes of PKP in 14 patients with CHED at the Royal Victoria Eye and Ear Hospital in Dublin from 1978 to 2013 were described following case note review. The main outcome measures were best-corrected visual acuity (BCVA) and graft survival.ResultsThirty-three corneal transplants were performed, which included 32 PKPs and one Descemet’s stripping endothelial keratoplasty. Twenty-four eyes underwent primary corneal grafts and nine eyes had regrafts. The graft survival rates at final follow-up were 37.5% and 33% in the primary graft and regraft groups, respectively. Preoperative BCVA was 20/200 or worse in all patients. At the final postoperative visit, the BCVA was 20/80 or better in four eyes following primary PKP, 20/160 in one eye following regrafting and was 20/200 or worse in all other eyes. The mean time to graft failure was 16 months (range 0–37 months). The mean follow-up time was 101 months (range 12–252 months). Fifty per cent of the patients continue to attend for follow-up.ConclusionsThis study has demonstrated a poor outcome from PKP for CHED in this Irish cohort. This arises from a combination of dense amblyopia and a high risk of graft failure in the long term.
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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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Chae H, Kim M, Kim Y, Kim J, Kwon A, Choi H, Park J, Jang W, Lee YS, Park SH, Kim MS. Mutational spectrum of Korean patients with corneal dystrophy. Clin Genet 2016; 89:678-89. [PMID: 26748743 DOI: 10.1111/cge.12726] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 12/29/2015] [Accepted: 01/04/2016] [Indexed: 11/29/2022]
Abstract
Corneal dystrophy typically refers to a group of rare hereditary disorders with a heterogeneous genetic background. A comprehensive molecular genetic analysis was performed to characterize the genetic spectrum of corneal dystrophies in Korean patients. Patients with various corneal dystrophies underwent thorough ophthalmic examination, histopathologic examination, and Sanger sequencing. A total of 120 probands were included, with a mean age of 50 years (SD = 18 years) and 70% were female. A total of 26 mutations in five genes (14 clearly pathogenic and 12 likely pathogenic) were identified in 49 probands (41%). Epithelial-stromal TGFBI dystrophies, macular corneal dystrophy and Schnyder corneal dystrophy (SCD) showed 100% mutation detection rates, while endothelial corneal dystrophies showed lower detection rates of 3%. Twenty six non-duplicate mutations including eight novel mutations were identified and mutations associated with SCD were identified genetically for the first time in this population. This study provides a comprehensive characterization of the genetic aberrations in Korean patients and also highlights the diagnostic value of molecular genetic analysis in corneal dystrophies.
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Affiliation(s)
- H Chae
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - M Kim
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Y Kim
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - J Kim
- Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - A Kwon
- Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - H Choi
- Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - J Park
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - W Jang
- Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Y S Lee
- Department of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - S H Park
- Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - M S Kim
- Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
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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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Kaul H, Suman M, Khan Z, Ullah MI, Ashfaq UA, Idrees S. Missense mutation in SLC4A11 in two Pakistani families affected with congenital hereditary endothelial dystrophy (CHED2). Clin Exp Optom 2015; 99:73-7. [PMID: 26286922 DOI: 10.1111/cxo.12276] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 10/29/2014] [Accepted: 11/06/2014] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Autosomal recessive congenital hereditary endothelial dystrophy (CHED2) is a recessively inherited eye disorder that is more common in consanguineous populations. METHODS Two families affected with CHED2 were recruited from the Punjab province of Pakistan to identify the underlying genetic defect. Blood samples from both the families, designated as CH01 and CH02, were collected. Genomic DNA was isolated. Initially, linkage analysis using microsatellite markers was carried out to confirm the linkage to the SLC4A11 gene, previously reported to be implicated in the pathology of the disease. Later on, sequencing was carried out to find the pathogenic mutation in the enrolled families. Identified variation was further confirmed by typing 50 ethnically matched normal control samples. RESULTS The results of linkage analysis indicated the putative linkage to SLAC4A11 gene, located at the CHED2 locus on chromosome 20p13-p12 in both families. Mutational analysis revealed an unidentified homozygous mutation c.2024A>C (p.E675A) in the affected members of both the families. Haplotype analysis of both the families showed that the affected members carry the same haplotype, thereby indicating a possibility of a common ancestral mutation. Use of bioinformatic tools including PolyPhen and SIFT suggested that a single amino acid change of E to A at position 675 affected the function of the protein. CONCLUSION This study reports a newly identified mutation (c.2024A>C) in the SLC4A11 gene segregating with the diseased haplotype in two consanguineous Pakistani families.
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Affiliation(s)
- Haiba Kaul
- Department of Biochemistry, University of Health Sciences, Lahore, Pakistan.
| | - Maryam Suman
- Department of Biotechnology, Kinnaird College, Lahore, Pakistan
| | - Zoya Khan
- Department of Biotechnology, Kinnaird College, Lahore, Pakistan
| | - Muhammad Ikram Ullah
- Department of Biochemistry, University of Health Sciences, Lahore, Pakistan.,Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Usman Ali Ashfaq
- Department of Bioinformatics and Biotechnology, Government College University Faisalabad, Pakistan
| | - Sobia Idrees
- Department of Bioinformatics and Biotechnology, Government College University Faisalabad, Pakistan
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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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Siddiqui S, Zenteno JC, Rice A, Chacón-Camacho O, Naylor SG, Rivera-de la Parra D, Spokes DM, James N, Toomes C, Inglehearn CF, Ali M. Congenital hereditary endothelial dystrophy caused by SLC4A11 mutations progresses to Harboyan syndrome. Cornea 2014; 33:247-51. [PMID: 24351571 PMCID: PMC4195577 DOI: 10.1097/ico.0000000000000041] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Supplemental Digital Content is Available in the Text. Purpose: Homozygous mutations in SLC4A11 cause 2 rare recessive conditions: congenital hereditary endothelial dystrophy (CHED), affecting the cornea alone, and Harboyan syndrome consisting of corneal dystrophy and sensorineural hearing loss. In addition, adult-onset Fuchs endothelial corneal dystrophy (FECD) is associated with dominant mutations in SLC4A11. In this report, we investigate whether patients with CHED go on to develop hearing loss and whether their parents, who are carriers of an SLC4A11 mutation, show signs of having FECD. Methods: Patients with CHED were screened for mutations in the SLC4A11 gene and underwent audiometric testing. The patients and their parents underwent a clinical examination and specular microscopy. Results: Molecular analyses confirmed SLC4A11 mutations in 4 affected individuals from 3 families. All the patients were found to have varying degrees of sensorineural hearing loss at a higher frequency range. Guttate lesions were seen in 2 of the 4 parents who were available for examination. Conclusions: Our observations suggest that CHED caused by homozygous SLC4A11 mutations progresses to Harboyan syndrome, but the severity of this may vary considerably. Patients with CHED should therefore be monitored for progressive hearing loss. We could not determine conclusively whether the parents of the patients with CHED were at increased risk of developing late-onset FECD.
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Affiliation(s)
- Salina Siddiqui
- *Section of Ophthalmology and Neuroscience, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, United Kingdom; †Department of Ophthalmology, St James's University Hospital, Leeds, United Kingdom; ‡Department of Biochemistry, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Mexico City, Mexico; §Department of Genetics, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico; and ¶Department of Ophthalmology, Bradford Royal Infirmary, Bradford, United Kingdom
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Loganathan SK, Casey JR. Corneal dystrophy-causing SLC4A11 mutants: suitability for folding-correction therapy. Hum Mutat 2014; 35:1082-91. [PMID: 24916015 DOI: 10.1002/humu.22601] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/28/2014] [Indexed: 12/25/2022]
Abstract
SLC4A11 mutations cause some cases of the corneal endothelial dystrophies, congenital hereditary endothelial corneal dystrophy type 2 (CHED2), Harboyan syndrome (HS), and Fuchs endothelial corneal dystrophy (FECD). SLC4A11 protein was recently identified as facilitating water flux across membranes. SLC4A11 point mutations usually cause SLC4A11 misfolding and retention in the endoplasmic reticulum (ER). We set about to test the feasibility of rescuing misfolded SLC4A11 protein to the plasma membrane as a therapeutic approach. Using a transfected HEK293 cell model, we measured functional activity present in cells expressing SLC4A11 variants in combinations representing the state found in CHED2 carriers, affected CHED2, FECD individuals, and unaffected individuals. These cells manifest respectively about 60%, 5%, and 25% of the water flux activity, relative to the unaffected (WT alone). ER-retained CHED2 mutant SLC4A11 protein could be rescued to the plasma membrane, where it conferred 25%-30% of WT water flux level. Further, some ER-retained CHED2 mutants expressed at 30°C supported increased water flux compared with 37°C cultures. Caspase activation and cell vitality assays revealed that expression of SLC4A11 mutants in HEK293 cells does not induce cell death. We conclude that therapeutics able to increase cell surface localization of ER-retained SLC4A11 mutants hold promise to treat CHED2 and FECD patients.
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Affiliation(s)
- Sampath K Loganathan
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
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Aldave AJ, Ann LB, Frausto RF, Nguyen CK, Yu F, Raber IM. Classification of posterior polymorphous corneal dystrophy as a corneal ectatic disorder following confirmation of associated significant corneal steepening. JAMA Ophthalmol 2014; 131:1583-90. [PMID: 24113819 DOI: 10.1001/jamaophthalmol.2013.5036] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
IMPORTANCE The identification of steep corneal curvatures in a significant percentage of patients with posterior polymorphous corneal dystrophy (PPCD) confirms this previously reported association and suggests a role for the ZEB1 protein in keratocyte function. OBJECTIVE To determine whether PPCD is characterized by significant corneal steepening. DESIGN, SETTING, AND PARTICIPANTS Cross-sectional study at university-based and private ophthalmology practices of 38 individuals (27 affected and 11 unaffected) from 23 families with PPCD. EXPOSURE Slitlamp examination and corneal topographic imaging were performed for individuals with PPCD and unaffected family members. Saliva or blood samples were obtained from each individual for DNA isolation and ZEB1 sequencing. Corneal ZEB1 expression was measured using immunohistochemistry. MAIN OUTCOMES AND MEASURES Percentage of individuals affected with PPCD and controls with an average keratometric value greater than 48.0 diopters (D) in each eye; the mean keratometric value averaged for both eyes of individuals with PPCD and controls; and the correlation of ZEB1 mutation with keratometric value. RESULTS ZEB1 coding region mutations were identified in 7 of the 27 affected individuals. Ten of the 38 individuals (26.3%) had average keratometric values greater than 48.0 D OU: 10 of 27 individuals with PPCD (37.0%; 6 of 7 individuals with ZEB1 mutations [85.7%] and 4 of 20 individuals without ZEB1 mutations [20.0%]) and 0 of 11 unaffected individuals (P = .04 for unaffected vs affected individuals; P = .004 for individuals with PPCD with vs without ZEB1 mutation). The mean keratometric value of each eye of affected individuals (48.2 D) was significantly greater than that of each eye of unaffected family members (44.1 D) (P = .03). Affected individuals with ZEB1 mutations demonstrated a mean keratometric value of 53.3 D, which was significantly greater than that of affected individuals without ZEB1 mutations (46.5 D; P = .004). Fluorescence immunohistochemistry demonstrated ZEB1 expression in keratocyte nuclei. CONCLUSIONS AND RELEVANCE Abnormally steep corneal curvatures are identified in 37% of all individuals with PPCD and 86% of affected individuals with PPCD secondary to ZEB1 mutations. ZEB1 is present in keratocyte nuclei, suggesting a role for ZEB1 in keratocyte function. Therefore, ZEB1 may play a role in both corneal stromal and endothelial development and function, and PPCD should be considered both an endothelial dystrophy and an ectatic disorder.
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Affiliation(s)
- Anthony J Aldave
- Jules Stein Eye Institute, David Geffen School of Medicine at University of California, Los Angeles
| | - Lydia B Ann
- Jules Stein Eye Institute, David Geffen School of Medicine at University of California, Los Angeles
| | - Ricardo F Frausto
- Jules Stein Eye Institute, David Geffen School of Medicine at University of California, Los Angeles
| | - Catherine K Nguyen
- Jules Stein Eye Institute, David Geffen School of Medicine at University of California, Los Angeles
| | - Fei Yu
- Jules Stein Eye Institute, David Geffen School of Medicine at University of California, Los Angeles
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Ogando DG, Jalimarada SS, Zhang W, Vithana EN, Bonanno JA. SLC4A11 is an EIPA-sensitive Na(+) permeable pHi regulator. Am J Physiol Cell Physiol 2013; 305:C716-27. [PMID: 23864606 DOI: 10.1152/ajpcell.00056.2013] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Slc4a11, a member of the solute linked cotransporter 4 family that is comprised predominantly of bicarbonate transporters, was described as an electrogenic 2Na(+)-B(OH)4(-) (borate) cotransporter and a Na(+)-2OH(-) cotransporter. The goal of the current study was to confirm and/or clarify the function of SLC4A11. In HEK293 cells transfected with SLC4A11 we tested if SLC4A11 is a: 1) Na(+)-HCO3(-) cotransporter, 2) Na(+)-OH(-)(H(+)) transporter, and/or 3) Na(+)-B(OH)4(-) cotransporter. CO2/HCO3(-) perfusion yielded no significant differences in rate or extent of pHi changes or Na(+) flux in SLC4A11-transfected compared with control cells. Similarly, in CO2/HCO3(-), acidification on removal of Na(+) and alkalinization on Na(+) add back were not significantly different between control and transfected indicating that SLC4A11 does not have Na(+)-HCO3(-) cotransport activity. In the absence of CO2/HCO3(-), SLC4A11-transfected cells showed higher resting intracelllular Na(+) concentration ([Na(+)]i; 25 vs. 17 mM), increased NH4(+)-induced acidification and increased acid recovery rate (160%) after an NH4 pulse. Na(+) efflux and influx were faster (80%) following Na(+) removal and add back, respectively, indicative of Na(+)-OH(-)(H(+)) transport by SLC4A11. The increased alkalinization recovery was confirmed in NHE-deficient PS120 cells demonstrating that SLC4A11 is a bonafide Na(+)-OH(-)(H(+)) transporter and not an activator of NHEs. SLC4A11-mediated H(+) efflux is inhibited by 5-(N-ethyl-N-isopropyl) amiloride (EIPA; EC50: 0.1 μM). The presence of 10 mM borate did not alter dpHi/dt or ΔpH during a Na(+)-free pulse in SLC4A11-transfected cells. In summary our results show that SLC4A11 is not a bicarbonate or borate-linked transporter but has significant EIPA-sensitive Na(+)-OH(-)(H(+)) and NH4(+) permeability.
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Affiliation(s)
- Diego G Ogando
- School of Optometry, Indiana University, Bloomington, Indiana
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Jalimarada SS, Ogando DG, Vithana EN, Bonanno JA. Ion transport function of SLC4A11 in corneal endothelium. Invest Ophthalmol Vis Sci 2013; 54:4330-40. [PMID: 23745003 DOI: 10.1167/iovs.13-11929] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE Mutations in SLC4A11, a member of the SLC4 superfamily of bicarbonate transporters, give rise to corneal endothelial cell dystrophies. SLC4A11 is a putative Na⁺ borate and Na⁺:OH⁻ transporter. Therefore we ask whether SLC4A11 in corneal endothelium transports borate (B[OH]₄⁻), bicarbonate (HCO3⁻), or hydroxyl (OH⁻) anions coupled to Na⁺. METHODS SLC4A11 expression in cultured primary bovine corneal endothelial cells (BCECs) was determined by semiquantitative PCR, SDS-PAGE/Western blotting, and immunofluorescence staining. Ion transport function was examined by measuring intracellular pH (pHi) or Na⁺ ([Na⁺](i)) in response to Ringer solutions with/without B(OH)₄⁻ or HCO₃⁻ after overexpressing or small interfering RNA (siRNA) silencing of SLC4A11. RESULTS SLC4A11 is localized to the basolateral membrane in BCEC. B(OH)₄⁻ (2.5-10 mM) in bicarbonate-free Ringer induced a rapid small acidification (0.01 pH unit) followed by alkalinization (0.05-0.1 pH unit), consistent with diffusion of boric acid into the cell followed by B(OH)₄⁻. However, the rate of B(OH)₄⁻-induced pHi change was unaffected by overexpression of SLC4A11. B(OH)₄⁻ did not induce significant changes in resting [Na⁺(i)] or the amplitude and rate of acidification caused by Na⁺ removal. siRNA-mediated knockdown of SLC4A11 (∼70%) did not alter pHi responses to CO₂/HCO₃⁻-rich Ringer, Na⁺-free induced acidification, or the rate of Na⁺ influx in the presence of bicarbonate. However, in the absence of bicarbonate, siSLC4A11 knockdown significantly decreased the rate (43%) and amplitude (48%) of acidification due to Na⁺ removal and recovery (53%) upon add-back. Additionally, the rate of acid recovery following NH₄⁺ prepulse was decreased significantly (27%) by SLC4A11 silencing. CONCLUSIONS In corneal endothelium, SLC4A11 displays robust Na⁺-coupled OH⁻ transport, but does not transport B(OH)₄⁻ or HCO₃⁻.
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Liu J, Seet LF, Koh LW, Venkatraman A, Venkataraman D, Mohan RR, Praetorius J, Bonanno JA, Aung T, Vithana EN. Depletion of SLC4A11 causes cell death by apoptosis in an immortalized human corneal endothelial cell line. Invest Ophthalmol Vis Sci 2012; 53:3270-9. [PMID: 22447871 DOI: 10.1167/iovs.11-8724] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the effects of SLC4A11 gene depletion in human corneal endothelial cells. METHODS To achieve stable downregulation of SLC4A11 gene expression in immortalized human corneal endothelial cells (HCECs), short-hairpin RNA (shRNA) targeted against SLC4A11 was used. Cell growth and viability were determined using the real-time cell analyzer and trypan blue staining respectively. Apoptosis was investigated by Annexin V and TUNEL assays. Alterations in apoptotic gene expression following SLC4A11 silencing were determined using the RT(2)Profiler PCR array for human apoptosis while activation of the apoptotic pathway was ascertained by western analysis. RESULTS SLC4A11 silencing in HCECs could be achieved by stable expression of shRNA targeted against SLC4A11. SLC4A11 knockdown suppressed HCEC growth and reduced HCEC viability compared to the control. This reduction in cell growth is associated with increased apoptosis in SLC4A11-silenced cells. CONCLUSIONS Our data suggest that the reduction of cell number with time in SLC4A11-depleted HCECs is due to an increase in cell death by apoptosis. This suggests that SLC4A11 is necessary for cell survival and may explain the pathologic corneal endothelial cell loss in endotheliopathies due to SLC4A11 mutations.
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Affiliation(s)
- Jun Liu
- Singapore Eye Research Institute, Singapore
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Vilas GL, Loganathan SK, Quon A, Sundaresan P, Vithana EN, Casey J. Oligomerization of SLC4A11 protein and the severity of FECD and CHED2 corneal dystrophies caused by SLC4A11 mutations. Hum Mutat 2011; 33:419-28. [PMID: 22072594 DOI: 10.1002/humu.21655] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 10/31/2011] [Indexed: 11/06/2022]
Abstract
Mutations in the SLC4A11 gene, which encodes a plasma membrane borate transporter, cause recessive congenital hereditary endothelial corneal dystrophy type 2 (CHED2), corneal dystrophy and perceptive deafness (Harboyan syndrome), and dominant late-onset Fuchs endothelial corneal dystrophy (FECD). We analyzed missense SLC4A11 mutations identified in FECD and CHED2 patients and expressed in transfected HEK 293 cells. Chemical cross-linking and migration in nondenaturing gels showed that SLC4A11 exists as a dimer. Furthermore, co-immunoprecipitation of epitope-tagged proteins revealed heteromeric interactions between wild-type (WT) and mutant SLC4A11 proteins. When expressed alone, FECD- and CHED2-causing mutant SLC4A11 proteins are primarily retained intracellularly. Co-expression with WT SLC4A11 partially rescued the cell surface trafficking of CHED2 mutants, but not FECD mutants. CHED2 alleles of SLC4A11 did not affect cell surface processing of WT SLC4A11. In contrast, FECD mutants reduced WT cell surface processing efficiency, consistent with dominant inheritance of FECD. The reduction in movement of WT protein to the cell surface caused by FECD SLC4A11 helps to explain the dominant inheritance of this disorder. Similarly, the failure of CHED2 mutant SLC4A11 to affect the processing of WT protein, explains the lack of symptoms found in CHED2 carriers and the recessive inheritance of the disorder.
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Affiliation(s)
- Gonzalo L Vilas
- Membrane Protein Disease Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Canada
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Vilas GL, Morgan PE, Loganathan SK, Quon A, Casey JR. A Biochemical Framework for SLC4A11, the Plasma Membrane Protein Defective in Corneal Dystrophies. Biochemistry 2011; 50:2157-69. [DOI: 10.1021/bi101887z] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Gonzalo L. Vilas
- Membrane Protein Disease Research Group, Department of Physiology, and Department of Biochemistry, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Canada T6G 2H7
| | - Patricio E. Morgan
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina CP1900
| | - Sampath K. Loganathan
- Membrane Protein Disease Research Group, Department of Physiology, and Department of Biochemistry, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Canada T6G 2H7
| | - Anita Quon
- Membrane Protein Disease Research Group, Department of Physiology, and Department of Biochemistry, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Canada T6G 2H7
| | - Joseph R. Casey
- Membrane Protein Disease Research Group, Department of Physiology, and Department of Biochemistry, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Canada T6G 2H7
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Molecular Genetics of Corneal Disease. Cornea 2011. [DOI: 10.1016/b978-0-323-06387-6.00019-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
PURPOSE The purposes of this study were to describe the clinical characteristics of corneal patients with mutations in the SLC4A11 gene and to determine if these characteristics could be correlated with specific genetic mutations. METHODS A retrospective case series review was conducted. Baseline demographic data, including gender, age at diagnosis of congenital hereditary endothelial dystrophy, family history, and pedigree information, were obtained. Information from clinical examination, including intraocular pressure, ultrasonic pachymetry, best spectacle-corrected visual acuity, axial length, and slit-lamp biomicroscopic evaluation, including corneal diameter and fundus examination, were also documented from the notes. History of corneal surgery was also recorded. Hearing loss was assessed by audiometry. Genetic analysis was performed by polymerase chain reaction amplification and sequencing. RESULTS Seven patients were identified. Four of the seven had associated hearing loss; all of the patients had undergone or were awaiting penetrating keratoplasty to one or both eyes. No correlation could be reached between the ocular phenotype and the gene mutation in this small sample. Individuals with the same mutation had different degrees of hearing loss within their respective families. CONCLUSIONS Corneal endothelial cells are more vulnerable to defects in the functional activity of SLC4A11 than cells of the striae vascularis of the inner ear. Both congenital hereditary endothelial dystrophy 2 and Harboyan syndrome have similar ocular phenotypes, ie, diffuse bilateral corneal edema present at birth or within the neonatal period; hence, audiometry must be performed to differentiate the two conditions.
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Lopez IA, Rosenblatt MI, Kim C, Galbraith GC, Jones SM, Kao L, Newman D, Liu W, Yeh S, Pushkin A, Abuladze N, Kurtz I. Slc4a11 gene disruption in mice: cellular targets of sensorineuronal abnormalities. J Biol Chem 2009; 284:26882-96. [PMID: 19586905 DOI: 10.1074/jbc.m109.008102] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
NaBC1 (the SLC4A11 gene) belongs to the SLC4 family of sodium-coupled bicarbonate (carbonate) transporter proteins and functions as an electrogenic sodium borate cotransporter. Mutations in SLC4A11 cause either corneal abnormalities (corneal hereditary dystrophy type 2) or a combined auditory and visual impairment (Harboyan syndrome). The role of NaBC1 in sensory systems is poorly understood, given the difficulty of studying patients with NaBC1 mutations. We report our findings in Slc4a11(-/-) mice generated to investigate the role of NaBC1 in sensorineural systems. In wild-type mice, specific NaBC1 immunoreactivity was detected in fibrocytes of the spiral ligament, from the basal to the apical portion of the cochlea. NaBC1 immunoreactivity was present in the vestibular labyrinth, in stromal cells underneath the non-immunoreactive sensory epithelia of the macula utricle, sacule, and crista ampullaris, and the membranous vestibular labyrinth was collapsed. Both auditory brain response and vestibular evoked potential waveforms were significantly abnormal in Slc4a11(-/-) mice. In the cornea, NaBC1 was highly expressed in the endothelial cell layer with less staining in epithelial cells. However, unlike humans, the corneal phenotype was mild with a normal slit lamp evaluation. Corneal endothelial cells were morphologically normal; however, both the absolute height of the corneal basal epithelial cells and the relative basal epithelial cell/total corneal thickness were significantly increased in Slc4a11(-/-) mice. Our results demonstrate for the first time the importance of NaBC1 in the audio-vestibular system and provide support for the hypothesis that SLC4A11 should be considered a potential candidate gene in patients with isolated sensorineural vestibular hearing abnormalities.
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Affiliation(s)
- Ivan A Lopez
- Division of Head and Neck, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA
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Abstract
The term corneal dystrophy embraces a heterogenous group of bilateral genetically determined non-inflammatory corneal diseases that are restricted to the cornea. The designation is imprecise but remains in vogue because of its clinical value. Clinically, the corneal dystrophies can be divided into three groups based on the sole or predominant anatomical location of the abnormalities. Some affect primarily the corneal epithelium and its basement membrane or Bowman layer and the superficial corneal stroma (anterior corneal dystrophies), the corneal stroma (stromal corneal dystrophies), or Descemet membrane and the corneal endothelium (posterior corneal dystrophies). Most corneal dystrophies have no systemic manifestations and present with variable shaped corneal opacities in a clear or cloudy cornea and they affect visual acuity to different degrees. Corneal dystrophies may have a simple autosomal dominant, autosomal recessive or X-linked recessive Mendelian mode of inheritance. Different corneal dystrophies are caused by mutations in the CHST6, KRT3, KRT12, PIP5K3, SLC4A11, TACSTD2, TGFBI, and UBIAD1 genes. Knowledge about the responsible genetic mutations responsible for these disorders has led to a better understanding of their basic defect and to molecular tests for their precise diagnosis. Genes for other corneal dystrophies have been mapped to specific chromosomal loci, but have not yet been identified. As clinical manifestations widely vary with the different entities, corneal dystrophies should be suspected when corneal transparency is lost or corneal opacities occur spontaneously, particularly in both corneas, and especially in the presence of a positive family history or in the offspring of consanguineous parents. Main differential diagnoses include various causes of monoclonal gammopathy, lecithin-cholesterol-acyltransferase deficiency, Fabry disease, cystinosis, tyrosine transaminase deficiency, systemic lysosomal storage diseases (mucopolysaccharidoses, lipidoses, mucolipidoses), and several skin diseases (X-linked ichthyosis, keratosis follicularis spinolosa decalvans). The management of the corneal dystrophies varies with the specific disease. Some are treated medically or with methods that excise or ablate the abnormal corneal tissue, such as deep lamellar endothelial keratoplasty (DLEK) and phototherapeutic keratectomy (PTK). Other less debilitating or asymptomatic dystrophies do not warrant treatment. The prognosis varies from minimal effect on the vision to corneal blindness, with marked phenotypic variability.
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Affiliation(s)
- Gordon K Klintworth
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, USA.
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