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Tsedilina TR, Sharova E, Iakovets V, Skorodumova LO. Systematic review of SLC4A11, ZEB1, LOXHD1, and AGBL1 variants in the development of Fuchs' endothelial corneal dystrophy. Front Med (Lausanne) 2023; 10:1153122. [PMID: 37441688 PMCID: PMC10333596 DOI: 10.3389/fmed.2023.1153122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 03/30/2023] [Indexed: 07/15/2023] Open
Abstract
Introduction The pathogenic role of variants in TCF4 and COL8A2 in causing Fuchs' endothelial corneal dystrophy (FECD) is not controversial and has been confirmed by numerous studies. The causal role of other genes, SLC4A11, ZEB1, LOXHD1, and AGBL1, which have been reported to be associated with FECD, is more complicated and less obvious. We performed a systematic review of the variants in the above-mentioned genes in FECD cases, taking into account the currently available population frequency information, transcriptomic data, and the results of functional studies to assess their pathogenicity. Methods Search for articles published in 2005-2022 was performed manually between July 2022 and February 2023. We searched for original research articles in peer-reviewed journals, written in English. Variants in the genes of interest identified in patients with FECD were extracted for the analysis. We classified each presented variant by pathogenicity status according to the ACMG criteria implemented in the Varsome tool. Diagnosis, segregation data, presence of affected relatives, functional analysis results, and gene expression in the corneal endothelium were taken into account. Data on the expression of genes of interest in the corneal endothelium were extracted from articles in which transcriptome analysis was performed. The identification of at least one variant in a gene classified as pathogenic or significantly associated with FECD was required to confirm the causal role of the gene in FECD. Results The analysis included 34 articles with 102 unique ZEB1 variants, 20 articles with 64 SLC4A11 variants, six articles with 26 LOXHD1 variants, and five articles with four AGBL1 variants. Pathogenic status was confirmed for seven SLC4A11 variants found in FECD. No variants in ZEB1, LOXHD1, and AGBL1 genes were classified as pathogenic for FECD. According to the transcriptome data, AGBL1 and LOXHD1 were not expressed in the corneal endothelium. Functional evidence for the association of LOXHD1, and AGBL1 with FECD was conflicting. Conclusion Our analysis confirmed the causal role of SLC4A11 variants in the development of FECD. The causal role of ZEB1, LOXHD1, and AGBL1 variants in FECD has not been confirmed. Further evidence from familial cases and functional analysis is needed to confirm their causal roles in FECD.
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Affiliation(s)
- Tatiana Romanovna Tsedilina
- Laboratory of Human Molecular Genetics, Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia
| | - Elena Sharova
- Laboratory of Human Molecular Genetics, Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia
| | - Valeriia Iakovets
- Laboratory of Human Molecular Genetics, Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia
- I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Liubov Olegovna Skorodumova
- Laboratory of Human Molecular Genetics, Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia
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Iqbal A, Naz S, Kaul H, Sharif S, Khushbakht A, Naeem MA, Iqtedar M, Kaleem A, Firasat S, Manzoor F. Mutational analysis in sodium-borate cotransporter SLC4A11 in consanguineous families from Punjab, Pakistan. PLoS One 2022; 17:e0273685. [PMID: 36037197 PMCID: PMC9423612 DOI: 10.1371/journal.pone.0273685] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 08/12/2022] [Indexed: 12/02/2022] Open
Abstract
AIM To identify the molecular basis of Congenital Hereditary Endothelial Dystrophy CHED caused by mutations in SLC4A11, in the consanguineous Pakistani families. METHODS A total of 7 consanguineous families affected with Congenital Hereditary Endothelial Dystrophy were diagnosed and registered with the help of ophthalmologists. Blood samples were collected from affected and unaffected members of the enrolled families. Mutational analysis was carried out by DNA sequencing using both Sanger and Whole Exome Sequencing (WES). Probands of each pedigree from the 7 families were used for WES. Results were analyzed with the help of different bioinformatics tools. RESULTS The sequencing results demonstrated three known homozygous mutations in gene SLC4A11 in probands of 7 families. These mutations p.Glu675Ala, p.Val824Met, and p.Arg158fs include 2 missense and 1 frameshift mutation. The mutations result in amino acids that were highly conserved in SLC4A11 across different species. The mutations were segregated with the disease phenotype in the families. CONCLUSION This study reports 3 mutations in 7 families. One of the pathogenic mutations (p.R158fs) was identified for the first time in the Pakistani population. However, two mutations (p.Glu675Ala, p.Val824Met) were previously reported in two and one Pakistani family respectively. As these mutations segregate with the disease phenotype and bioinformatics tool also liable them as pathogenic, they are deemed as probable cause of underlying disease.
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Affiliation(s)
- Afia Iqbal
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
| | - Shagufta Naz
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
| | - Haiba Kaul
- Department of Animal Breeding and Genetics, Genetics Discipline, University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Saima Sharif
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
| | - Aysha Khushbakht
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
| | - Muhammad Asif Naeem
- Vision Impairment Lab of Genetic Diseases Group, Center of Excellence in Molecular Biology, Lahore, Pakistan
| | - Mehwish Iqtedar
- Department of Biotechnology, Lahore College for Women University, Lahore, Pakistan
| | - Afshan Kaleem
- Department of Biotechnology, Lahore College for Women University, Lahore, Pakistan
| | - Sabika Firasat
- Department of Biological Sciences, Quaid-e-Azam University, Islamabad, Pakistan
| | - Farkhanda Manzoor
- Department of Zoology, Lahore College for Women University, Lahore, Pakista
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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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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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Choi M, Bonanno JA. Mitochondrial Targeting of the Ammonia-Sensitive Uncoupler SLC4A11 by the Chaperone-Mediated Carrier Pathway in Corneal Endothelium. Invest Ophthalmol Vis Sci 2021; 62:4. [PMID: 34499705 PMCID: PMC8434753 DOI: 10.1167/iovs.62.12.4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Purpose SLC4A11, an electrogenic H+ transporter, is found in the plasma membrane and mitochondria of corneal endothelium. However, the underlying mechanism of SLC4A11 targeting to mitochondria is unknown. Methods The presence of mitochondrial targeting sequences was examined using in silico mitochondrial proteomic analyses. Thiol crosslinked peptide binding to SLC4A11 was screened by untargeted liquid chromatography/tandem mass spectrometry (LC-MS/MS) analysis. Direct protein interactions between SLC4A11 and chaperones were examined using coimmunoprecipitation analysis and proximity ligation assay. Knockdown or pharmacologic inhibition of chaperones in human corneal endothelial cells (HCECs) or mouse corneal endothelial cells (MCECs), ex vivo kidney, or HA-SLC4A11–transfected fibroblasts was performed to investigate the functional consequences of interfering with mitochondrial SLC4A11 trafficking. Results SLC4A11 does not contain canonical N-terminal mitochondrial targeting sequences. LC-MS/MS analysis showed that HSC70 and/or HSP90 are bound to HA-SLC4A11–transfected PS120 fibroblast whole-cell lysates or isolated mitochondria, suggesting trafficking through the chaperone-mediated carrier pathway. SLC4A11 and either HSP90 or HSC70 complexes are directly bound to the mitochondrial surface receptor, TOM70. Interference with this trafficking leads to dysfunctional mitochondrial glutamine catabolism and increased reactive oxygen species production. In addition, glutamine (Gln) use upregulated SLC4A11, HSP70, and HSP90 expression in whole-cell lysates or purified mitochondria of HCECs and HA-SLC4A11–transfected fibroblasts. Conclusions HSP90 and HSC70 are critical in mediating mitochondrial SLC4A11 translocation in corneal endothelial cells and kidney. Gln promotes SLC4A11 import to the mitochondria, and the continuous oxidative stress derived from Gln catabolism induced HSP70 and HSP90, protecting cells against oxidative stress.
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Affiliation(s)
- Moonjung Choi
- Vision Science Program, Indiana University, School of Optometry, Bloomington, Indiana, United States
| | - Joseph A Bonanno
- Vision Science Program, Indiana University, School of Optometry, Bloomington, Indiana, United States
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Chibani Z, Abid IZ, Söderkvist P, Feki J, Aifa MH. Autosomal recessive congenital hereditary corneal dystrophy associated with a novel SLC4A11 mutation in two consanguineous Tunisian families. Br J Ophthalmol 2021; 106:281-287. [PMID: 33879471 DOI: 10.1136/bjophthalmol-2020-318204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/11/2021] [Accepted: 03/20/2021] [Indexed: 11/03/2022]
Abstract
BACKGROUND Autosomal recessive congenital hereditary corneal dystrophy (CHED) is a rare isolated developmental anomaly of the eye characterised by diffuse bilateral corneal clouding that may lead to visual impairment requiring corneal transplantation. CHED is known to be caused by mutations in the solute carrier family 4 member 11 (SLC4A11) gene which encodes a membrane transporter protein (sodium bicarbonate transporter-like solute carrier family 4 member 11). METHODS To identify SLC4A11 gene mutations associated with CHED (OMIM: #217700), genomic DNA was extracted from whole blood and sequenced for all exons and intron-exon boundaries in two large Tunisian families. RESULTS A novel deletion SLC4A11 mutation (p. Leu479del; c.1434_1436del) is responsible for CHED in both analysed families. This non-frameshift mutation was found in a homozygous state in affected members and heterozygous in non-affected members. In silico analysis largely support the pathogenicity of this alteration that may leads to stromal oedema by disrupting the osmolarity balance. Being localised to a region of alpha-helical secondary structure, Leu479 deletion may induce protein-compromising structural rearrangements. CONCLUSION To the best of our knowledge, this is the first clinical and genetic study exploring CHED in Tunisia. The present work also expands the list of pathogenic genotypes in SLC4A11 gene and its associated clinical diagnosis giving more insights into genotype-phenotype correlations.
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Affiliation(s)
- Zohra Chibani
- Molecular and Functional Genetics Laboratory, University of Sfax, Faculty of Science of Sfax, Sfax, Tunisia
| | - Imen Zone Abid
- Department of Ophthalmology, Habib Bourguiba University Hospital, University of Sfax, Sfax, Tunisia
| | - Peter Söderkvist
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Jamel Feki
- Department of Ophthalmology, Habib Bourguiba University Hospital, University of Sfax, Sfax, Tunisia
| | - Mounira Hmani Aifa
- Molecular and Functional Genetics Laboratory, University of Sfax, Faculty of Science of Sfax, Sfax, Tunisia
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Lovatt M, Kocaba V, Hui Neo DJ, Soh YQ, Mehta JS. Nrf2: A unifying transcription factor in the pathogenesis of Fuchs' endothelial corneal dystrophy. Redox Biol 2020; 37:101763. [PMID: 33099215 PMCID: PMC7578533 DOI: 10.1016/j.redox.2020.101763] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 12/19/2022] Open
Abstract
Nuclear factor, erythroid 2 like 2 (Nrf2), is an oxidative stress induced transcription factor that regulates cytoprotective gene expression. Thus, Nrf2 is essential for cellular redox homeostasis. Loss or dysregulation of Nrf2 expression has been implicated in the pathogenesis of degenerative diseases, including diseases of the cornea. One of the most common diseases of the cornea in which Nrf2 is implicated is Fuchs' endothelial cornea dystrophy (FECD). FECD is the leading indication for corneal transplantation; and is associated with a loss of corneal endothelial cell (CEC) function. In this review, we propose that Nrf2 is an essential regulator of CEC function. Furthermore, we demonstrate that deficiency of Nrf2 function is a hallmark of FECD. In addition, we advocate that pharmacological targeting of Nrf2 as a possible therapy for FECD.
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Affiliation(s)
- Matthew Lovatt
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore.
| | - Viridiana Kocaba
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore; Netherlands Institute for Innovative Ocular Surgery (NIIOS), Rotterdam, the Netherlands
| | - Dawn Jing Hui Neo
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore
| | - Yu Qiang Soh
- Department of Cornea and External Eye Disease, Singapore National Eye Centre, Singapore
| | - Jodhbir S Mehta
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore; Department of Cornea and External Eye Disease, Singapore National Eye Centre, Singapore; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore.
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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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Matthaei M, Hribek A, Clahsen T, Bachmann B, Cursiefen C, Jun AS. Fuchs Endothelial Corneal Dystrophy: Clinical, Genetic, Pathophysiologic, and Therapeutic Aspects. Annu Rev Vis Sci 2020; 5:151-175. [PMID: 31525145 DOI: 10.1146/annurev-vision-091718-014852] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Fuchs endothelial corneal dystrophy (FECD) is a bilateral corneal endothelial disorder and the most common cause of corneal transplantation worldwide. Professor Ernst Fuchs described the first 13 cases of FECD more than 100 years ago. Since then, we have seen far-reaching progress in its diagnosis and treatment. In the field of diagnostics, new technologies enable the development of more accurate classification systems and the more detailed breakdown of the genetic basis of FECD. Laboratory studies help in deciphering the molecular pathomechanisms. The development of minimally invasive surgical techniques leads to a continuous improvement of the postoperative result. This review highlights and discusses clinical, genetic, pathophysiologic, and therapeutic aspects of this common and important corneal disorder.
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Affiliation(s)
- Mario Matthaei
- Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, 50937 Cologne, Germany; , , , ,
| | - Agathe Hribek
- Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, 50937 Cologne, Germany; , , , ,
| | - Thomas Clahsen
- Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, 50937 Cologne, Germany; , , , ,
| | - Björn Bachmann
- Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, 50937 Cologne, Germany; , , , ,
| | - Claus Cursiefen
- Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, 50937 Cologne, Germany; , , , ,
| | - Albert S Jun
- Wilmer Eye Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA;
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Jiang X, Jin X, Zhang N, Zhang H. A family of fuchs endothelial corneal dystrophy and anterior polar cataract with an analysis of whole exome sequencing. Ophthalmic Genet 2020; 41:263-270. [PMID: 32367751 DOI: 10.1080/13816810.2020.1759109] [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: 10/24/2022]
Abstract
PURPOSE Our aim was to introduce a family affected by this rare phenotype, and perform the whole exome sequencing (WES) to explore the potential candidate genes causing the disorders. METHODS A five-generation family including five patients affected by FECD with APC, and nine patients suffered from only FECD was recruited from the First Affiliated Hospital of Harbin Medical University. All participants received ophthalmic examinations. Eight family members were selected to perform WES with a bioinformatics analysis and genome-wide linkage analysis. The candidate genes were identified by polymerase chain reaction (PCR) and Sanger sequencing. RESULTS Patients in this family had FECD as the common feature. The proband (a 65-year-old female) was affected by FECD and APC in both eyes, with epithelial bullae in the left eye. Slit-lamp, specular, and confocal microscope and OCT images showed guttae more serious in the central cornea than the peripheral area, confirming the diagnosis of FECD. In this family, most corneal guttae was bilateral with an almost equal degree of progression in the Descemet membrane, APC was found around the age of 10, perhaps even earlier. According to the analysis of bioinformatics analysis, two candidate genes were found and confirmed by PCR and Sanger sequencing, but could not achieve genotype-phenotype co-segregation in the family. CONCLUSION We introduced a family of FECD with APC, with no known causative gene found by WES, inferring that there may be a novel gene-locus in the non-coding regions of genome, which needs further study by WGS. The contribution of this study was to exclude the possibility of the rare phenotype pathogenic site in exome and narrow the scope of pathogenic genes.
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Affiliation(s)
- Xue Jiang
- Department of Ophthalmology, The First Affiliated Hospital of Harbin Medical University , Harbin, P.R. China
| | - Xin Jin
- Department of Ophthalmology, The First Affiliated Hospital of Harbin Medical University , Harbin, P.R. China
| | - Nan Zhang
- Department of Ophthalmology, The First Affiliated Hospital of Harbin Medical University , Harbin, P.R. China
| | - Hong Zhang
- Department of Ophthalmology, The First Affiliated Hospital of Harbin Medical University , Harbin, P.R. China
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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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Malhotra D, Loganathan SK, Chiu AM, Lukowski CM, Casey JR. Human Corneal Expression of SLC4A11, a Gene Mutated in Endothelial Corneal Dystrophies. Sci Rep 2019; 9:9681. [PMID: 31273259 PMCID: PMC6609610 DOI: 10.1038/s41598-019-46094-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 06/21/2019] [Indexed: 12/21/2022] Open
Abstract
Two blinding corneal dystrophies, pediatric-onset congenital hereditary endothelial dystrophy (CHED) and some cases of late-onset Fuchs endothelial corneal dystrophy (FECD), are caused by SLC4A11 mutations. Three N-terminal SLC4A11 variants: v1, v2 and v3 are expressed in humans. We set out to determine which of these transcripts and what translated products, are present in corneal endothelium as these would be most relevant for CHED and FECD studies. Reverse transcription PCR (RT-PCR) and quantitative RT-PCR revealed only v2 and v3 mRNA in human cornea, but v2 was most abundant. Immunoblots probed with variant-specific antibodies revealed that v2 protein is about four times more abundant than v3 in human corneal endothelium. Bioinformatics and protein analysis using variant-specific antibodies revealed that second methionine in the open reading frame (M36) acts as translation initiation site on SLC4A11 v2 in human cornea. The v2 variants starting at M1 (v2-M1) and M36 (v2-M36) were indistinguishable in their cell surface trafficking and transport function (water flux). Structural homology models of v2-M36 and v3 suggest structural differences but their significance remains unclear. A combination of bioinformatics, RNA quantification and isoform-specific antibodies allows us to conclude that SLC4A11 variant 2 with start site M36 is predominant in corneal endothelium.
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Affiliation(s)
- Darpan Malhotra
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Sampath K Loganathan
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.,Lunenfeld-Tanenbaum Research Institute, Toronto, Ontario, M5G 1X5, Canada
| | - Anthony M Chiu
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Chris M Lukowski
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Joseph R Casey
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.
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13
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Ogando DG, Choi M, Shyam R, Li S, Bonanno JA. Ammonia sensitive SLC4A11 mitochondrial uncoupling reduces glutamine induced oxidative stress. Redox Biol 2019; 26:101260. [PMID: 31254733 PMCID: PMC6604051 DOI: 10.1016/j.redox.2019.101260] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 06/07/2019] [Accepted: 06/21/2019] [Indexed: 02/07/2023] Open
Abstract
SLC4A11 is a NH3 sensitive membrane transporter with H+ channel-like properties that facilitates Glutamine catabolism in Human and Mouse corneal endothelium (CE). Loss of SLC4A11 activity induces oxidative stress and cell death, resulting in Congenital Hereditary Endothelial Dystrophy (CHED) with corneal edema and vision loss. However, the mechanism by which SLC4A11 prevents ROS production and protects CE is unknown. Here we demonstrate that SLC4A11 is localized to the inner mitochondrial membrane of CE and SLC4A11 transfected PS120 fibroblasts, where it acts as an NH3-sensitive mitochondrial uncoupler that enhances glutamine-dependent oxygen consumption, electron transport chain activity, and ATP levels by suppressing damaging Reactive Oxygen Species (ROS) production. In the presence of glutamine, Slc4a11-/- (KO) mouse CE generate significantly greater mitochondrial superoxide, a greater proportion of damaged depolarized mitochondria, and more apoptotic cells than WT. KO CE can be rescued by MitoQ, reducing NH3 production by GLS1 inhibition or dimethyl αKetoglutarate supplementation, or by BAM15 mitochondrial uncoupling. Slc4a11 KO mouse corneal edema can be partially reversed by αKetoglutarate eye drops. Moreover, we demonstrate that this role for SLC4A11 is not specific to CE cells, as SLC4A11 knockdown in glutamine-addicted colon carcinoma cells reduced glutamine catabolism, increased ROS production, and inhibited cell proliferation. Overall, our studies reveal a unique metabolic mechanism that reduces mitochondrial oxidative stress while promoting glutamine catabolism.
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Affiliation(s)
- Diego G Ogando
- Indiana University, School of Optometry, Bloomington, IN, 47405, United States
| | - Moonjung Choi
- Indiana University, School of Optometry, Bloomington, IN, 47405, United States
| | - Rajalekshmy Shyam
- Indiana University, School of Optometry, Bloomington, IN, 47405, United States
| | - Shimin Li
- Indiana University, School of Optometry, Bloomington, IN, 47405, United States
| | - Joseph A Bonanno
- Indiana University, School of Optometry, Bloomington, IN, 47405, United States.
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Abstract
Fuchs' endothelial corneal dystrophy (FECD) is a common disease resulting from corneal endothelial cell dysfunction. It is inherited in an autosomal dominant fashion with incomplete penetrance, and with a female bias. Approximately half of cases occur sporadically, and the remainder are familial. Early and late-onset forms of the disease exist. A review of the literature has revealed more than 15 genes harbouring mutations and/or single nucleotide polymorphisms associated with FECD. The proteins encoded by these genes cover a wide range of endothelial function, including transcription regulation, DNA repair, mitochondrial DNA mutations, targeting of proteins to the cell membrane, deglutamylation of proteins, extracellular matrix secretion, formation of cell-cell and cell-extracellular matrix junctions, water pump, and apoptosis. These genetic variations will form the platform for the further understanding of the pathological basis of the disease, and the development of targeted treatments. This review aims to summarise known genetic variations associated with FECD, discuss any known molecular effects of the variations, how these provide opportunities for targeted therapies, and what therapies are currently in development.
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15
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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: 2] [Impact Index Per Article: 0.4] [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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16
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Li S, Hundal KS, Chen X, Choi M, Ogando DG, Obukhov AG, Bonanno JA. R125H, W240S, C386R, and V507I SLC4A11 mutations associated with corneal endothelial dystrophy affect the transporter function but not trafficking in PS120 cells. Exp Eye Res 2019; 180:86-91. [PMID: 30557570 PMCID: PMC6389376 DOI: 10.1016/j.exer.2018.12.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 11/28/2018] [Accepted: 12/11/2018] [Indexed: 11/26/2022]
Abstract
SLC4A11 mutations are associated with Fuchs' endothelial corneal dystrophy (FECD), congenital hereditary endothelial dystrophy (CHED) and Harboyan syndrome (endothelial dystrophy with auditory deficiency). Mice with genetically ablated Slc4a11 recapitulate CHED, exhibiting significant corneal edema and altered endothelial morphology. We recently demonstrated that SLC4A11 functions as an NH3 sensitive, electrogenic H+ transporter. Here, we investigated the properties of five clinically relevant SLC4A11 mutants: R125H, W240S, C386R, V507I and N693A, relative to wild type, expressed in a PS120 fibroblast cell line. The effect of these mutations on the NH4Cl-dependent transporter activity was investigated by intracellular pH and electrophysiology measurements. Relative to plasma membrane expression of NaK ATPase, there were no significant differences in plasma membrane SLC4A11 expression among each mutant and wild type. All mutants revealed a marked decrease in acidification in response to NH4Cl when compared to wild type, indicating a decreased H+ permeability in mutants. All mutants exhibited significantly reduced H+ currents at negative holding potentials as compared to wild type. Uniquely, the C386R and W240S mutants exhibited a different inward current profile upon NH4Cl challenges, suggesting an altered transport mode. Thus, our data suggest that these SLC4A11 mutants, rather than having impaired protein trafficking, show altered H+ flux properties.
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Affiliation(s)
- Shimin Li
- School of Optometry, Indiana University Bloomington, Bloomington, IN, USA
| | - Karmjot Singh Hundal
- Department of Cellular & Integrative Physiology - IU School of Medicine, Indianapolis, IN, USA
| | - Xingjuan Chen
- Department of Cellular & Integrative Physiology - IU School of Medicine, Indianapolis, IN, USA
| | - Moonjung Choi
- School of Optometry, Indiana University Bloomington, Bloomington, IN, USA
| | - Diego G Ogando
- School of Optometry, Indiana University Bloomington, Bloomington, IN, USA
| | - Alexander G Obukhov
- Department of Cellular & Integrative Physiology - IU School of Medicine, Indianapolis, IN, USA.
| | - Joseph A Bonanno
- School of Optometry, Indiana University Bloomington, Bloomington, IN, USA.
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17
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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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18
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Liu W, Tang FL, Lin S, Zhao K, Mei L, Ye J, Xiong WC. Vps35-deficiency impairs SLC4A11 trafficking and promotes corneal dystrophy. PLoS One 2017; 12:e0184906. [PMID: 28934248 PMCID: PMC5608277 DOI: 10.1371/journal.pone.0184906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/01/2017] [Indexed: 12/17/2022] Open
Abstract
Vps35 (vacuolar protein sorting 35) is a major component of retromer that selectively promotes endosome-to-Golgi retrieval of transmembrane proteins. Dysfunction of retromer is a risk factor for the pathogenesis of Parkinson’s disease (PD) and Alzheimer’s disease (AD). However, Vps35/retromer’s function in the eye or the contribution of Vps35-deficiency to eye degenerative disorders remains to be explored. Here we provide evidence for a critical role of Vps35 in mouse corneal dystrophy. Vps35 is expressed in mouse and human cornea. Mouse cornea from Vps35 heterozygotes (Vps35+/-) show features of dystrophy, such as loss of both endothelial and epithelial cell densities, disorganizations of endothelial, stroma, and epithelial cells, excrescences in the Descemet membrane, and corneal edema. Additionally, corneal epithelial cell proliferation was reduced in Vps35-deficient mice. Intriguingly, cell surface targeting of SLC4A11, a membrane transport protein (OH- /H+ /NH3 /H2O) of corneal endothelium, whose mutations have been identified in patients with corneal dystrophy, was impaired in Vps35-deficient cells and cornea. Taken together, these results suggest that SLC4A11 appears to be a Vps35/retromer cargo, and Vps35-regulation of SLC4A11 trafficking may underlie Vps35/retromer regulation of corneal dystrophy.
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Affiliation(s)
- Wei Liu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Ophthalmology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, China
| | - Fu-Lei Tang
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Sen Lin
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Ophthalmology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, China
| | - Kai Zhao
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Lin Mei
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Jian Ye
- Department of Ophthalmology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, China
- * E-mail: (WX); (JY)
| | - Wen-Cheng Xiong
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
- * E-mail: (WX); (JY)
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19
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Kumawat BL, Gupta R, Sharma A, Sen S, Gupta S, Tandon R. Delayed onset of congenital hereditary endothelial dystrophy due to compound heterozygous SLC4A11 mutations. Indian J Ophthalmol 2017; 64:492-5. [PMID: 27609159 PMCID: PMC5026072 DOI: 10.4103/0301-4738.190100] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background: Congenital hereditary endothelial dystrophy (CHED) is an autosomal recessive disorder characterized by bilateral, symmetrical, noninflammatory corneal clouding (edema) present at birth or shortly thereafter. This study reports on an unusual delayed presentation of CHED with compound heterozygous SLC4A11 mutations. Materials and Methods: A 45-year-old female, presenting with bilateral decreased vision since childhood that deteriorated in the last 5 years, was evaluated to rule out trauma, viral illness, chemical injury, glaucoma, and corneal endothelial dystrophies. Tear sample was sent for herpes simplex viral (HSV) antigen testing. Genomic DNA from peripheral blood was screened for mutations in all exons of SLC4A11 by direct sequencing. Full-thickness penetrating keratoplasty was done and corneal button was sent for histopathological examination. Results: Slit-lamp findings revealed bilateral diffuse corneal edema and left eye spheroidal degeneration with scarring. Increased corneal thickness (762 μm and 854 μm in the right and left eyes, respectively), normal intraocular pressure (12 mmHg and 16 mmHg in the right and left eyes, respectively), inconclusive confocal scan, and specular microscopy, near normal tear film parameters, were the other clinical features. HSV-polymerase chain reaction was negative. Histopathological examination revealed markedly thickened Descemet's membrane with subepithelial spheroidal degeneration. SLC4A11 screening showed a novel variant p.Ser415Asn, reported mutation p.Cys386Arg and two polymorphisms, all in the heterozygous state and not identified in 100 controls. Conclusions: The study shows, for the first time, compound heterozygous SLC4A11 mutations impair protein function leading to delayed onset of the disease.
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Affiliation(s)
- Babu Lal Kumawat
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Ranjan Gupta
- Department of Anatomy, Laboratory of Cyto-Molecular Genetics, All India Institute of Medical Sciences, New Delhi, India
| | - Arundhati Sharma
- Department of Anatomy, Laboratory of Cyto-Molecular Genetics, All India Institute of Medical Sciences, New Delhi, India
| | - Seema Sen
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Shikha Gupta
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Radhika Tandon
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
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20
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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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21
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Ali M, Raghunathan V, Li JY, Murphy CJ, Thomasy SM. Biomechanical relationships between the corneal endothelium and Descemet's membrane. Exp Eye Res 2016; 152:57-70. [PMID: 27639516 DOI: 10.1016/j.exer.2016.09.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 09/13/2016] [Indexed: 12/28/2022]
Abstract
The posterior face of the cornea consists of the corneal endothelium, a monolayer of cuboidal cells that secrete and attach to Descemet's membrane, an exaggerated basement membrane. Dysfunction of the endothelium compromises the barrier and pump functions of this layer that maintain corneal deturgesence. A large number of corneal endothelial dystrophies feature irregularities in Descemet's membrane, suggesting that cells create and respond to the biophysical signals offered by their underlying matrix. This review provides an overview of the bidirectional relationship between Descemet's membrane and the corneal endothelium. Several experimental methods have characterized a richly topographic and compliant biophysical microenvironment presented by the posterior surface of Descemet's membrane, as well as the ultrastructure and composition of the membrane as it builds during a lifetime. We highlight the signaling pathways involved in the mechanotransduction of biophysical cues that influence cell behavior. We present the specific example of Fuchs' corneal endothelial dystrophy as a condition in which a dysregulated Descemet's membrane may influence the progression of disease. Finally, we discuss some disease models and regenerative strategies that may facilitate improved treatments for corneal dystrophies.
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Affiliation(s)
- Maryam Ali
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
| | - VijayKrishna Raghunathan
- The Ocular Surface Institute, College of Optometry, University of Houston, Houston, TX, 77204, USA.
| | - Jennifer Y Li
- Department of Ophthalmology & Vision Science, School of Medicine, UC Davis Medical Center, Sacramento, CA, 95817, USA.
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA; Department of Ophthalmology & Vision Science, School of Medicine, UC Davis Medical Center, Sacramento, CA, 95817, USA.
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
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22
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Kao L, Azimov R, Shao XM, Frausto RF, Abuladze N, Newman D, Aldave AJ, Kurtz I. Multifunctional ion transport properties of human SLC4A11: comparison of the SLC4A11-B and SLC4A11-C variants. Am J Physiol Cell Physiol 2016; 311:C820-C830. [PMID: 27581649 DOI: 10.1152/ajpcell.00233.2016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 08/30/2016] [Indexed: 12/13/2022]
Abstract
Congenital hereditary endothelial dystrophy (CHED), Harboyan syndrome (CHED with progressive sensorineural deafness), and potentially a subset of individuals with late-onset Fuchs' endothelial corneal dystrophy are caused by mutations in the SLC4A11 gene that results in corneal endothelial cell abnormalities. Originally classified as a borate transporter, the function of SLC4A11 as a transport protein remains poorly understood. Elucidating the transport function(s) of SLC4A11 is needed to better understand how its loss results in the aforementioned posterior corneal dystrophic disease processes. Quantitative PCR experiments demonstrated that, of the three known human NH2-terminal variants, SLC4A11-C is the major transcript expressed in human corneal endothelium. We studied the expression pattern of the three variants in mammalian HEK-293 cells and demonstrated that the SLC4A11-B and SLC4A11-C variants are plasma membrane proteins, whereas SLC4A11-A is localized intracellularly. SLC4A11-B and SLC4A11-C were shown to be multifunctional ion transporters capable of transporting H+ equivalents in both a Na+-independent and Na+-coupled mode. In both transport modes, SLC4A11-C H+ flux was significantly greater than SLC4A11-B. In the presence of ammonia, SLC4A11-B and SLC4A11-C generated inward currents that were comparable in magnitude. Chimera SLC4A11-C-NH2-terminus-SLC4A11-B experiments demonstrated that the SLC4A11-C NH2-terminus functions as an autoactivating domain, enhancing Na+-independent and Na+-coupled H+ flux without significantly affecting the electrogenic NH3-H(n)+ cotransport mode. All three modes of transport were significantly impaired in the presence of the CHED causing p.R109H (SLC4A11-C numbering) mutation. These complex ion transport properties need to be addressed in the context of corneal endothelial disease processes caused by mutations in SLC4A11.
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Affiliation(s)
- Liyo Kao
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Rustam Azimov
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Xuesi M Shao
- Department of Neurobiology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ricardo F Frausto
- Stein Eye Institute, and.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Natalia Abuladze
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Debra Newman
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Anthony J Aldave
- Stein Eye Institute, and.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ira Kurtz
- Division of Nephrology, .,Brain Research Institute.,David Geffen School of Medicine, University of California, Los Angeles, California
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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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Kim JH, Ko JM, Tchah H. Fuchs Endothelial Corneal Dystrophy in a Heterozygous Carrier of Congenital Hereditary Endothelial Dystrophy Type 2 with a Novel Mutation in SLC4A11. Ophthalmic Genet 2016; 36:284-6. [PMID: 24502824 DOI: 10.3109/13816810.2014.881510] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Congenital hereditary endothelial dystrophy (CHED) is a rare genetic disorder caused by mutations in corneal endothelial cells. CHED can be divided into 2 types by the modes of inheritance; CHED type 1 (CHED1) with autosomal dominant inheritance and CHED type 2 (CHED2) with autosomal recessive inheritance. Mutations in the sodium bicarbonate transporter-like solute carrier family 4 member 11 (SLC4A11) gene result CHED2. METHODS A 37 years old female was clinically diagnosed as CHED2. Peripheral blood from the patient and her family members was obtained under informed consents. Genomic DNA was extracted in their WBCs, and whole exons and exon-intron boundaries of the SLC4A11 gene were amplified using polymerase chain reaction. The amplified materials were analyzed by direct sequencing method. RESULTS The sequencing results of the SLC4A11 gene showed a novel homozygous mutation in exon 9 (c.1158C > A, p.C386*) in the proband with CHED2 phenotype. Her father and sister showing normal cornea were heterozygous carriers of the mutation. Her mother showing late onset Fuchs endothelial corneal dystrophy (FECD) also had the same mutation heterozygously. DISCUSSION We report a novel nonsense mutation of the SLC4A11 gene in the patient with CHED2. In addition, one of heterozygous carriers in this family showed features of late onset FECD. Close clinical ocular examination for the heterozygous carriers should be performed to detect late onset FECD.
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Affiliation(s)
- Jae-hyung Kim
- a Department of Ophthalmology , College of Medicine, Chungbuk National University , Cheongju , Korea
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Boron Induces Lymphocyte Proliferation and Modulates the Priming Effects of Lipopolysaccharide on Macrophages. PLoS One 2016; 11:e0150607. [PMID: 26934748 PMCID: PMC4774930 DOI: 10.1371/journal.pone.0150607] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 02/17/2016] [Indexed: 12/26/2022] Open
Abstract
Chemical mediators of inflammation (CMI) are important in host defense against infection. The reduced capacity of host to induce the secretion of these mediators following infection is one of the factors in host susceptibility to infection. Boron, which has been suggested for its role in infection, is reported in this study to increase lymphocyte proliferation and the secretion of CMI by the lipopolysaccharide (LPS)-stimulated peritoneal macrophages in BALB/c mice. Boron was administered to mice orally as borax at different doses for 10 consecutive days, followed by the stimulation of animals with ovalbumin and isolation of splenocytes for proliferation assay. The lymphocyte subsets were determined by flow cytometry in spleen cell suspension. The mediators of inflammation, TNF-α, IL-6, IL-1β and nitric oxide (NO), were measured in culture supernatant of LPS-primed macrophages isolated from borax treated mice. TNF and ILs were measured by ELISA. NO was determined by Griess test. The expression of inducible nitric oxide synthase (iNOS) in macrophages was studied by confocal microscopy. Results showed a significant increase in T and B cell populations, as indicated by an increase in CD4 and CD19, but not CD8, cells. Boron further stimulated the secretion of TNF-α, IL-6, IL-1β, NO and the expression of iNOS by the LPS-primed macrophages. The effect was dose dependent and most significant at a dose level of 4.6 mg/kg b. wt. Taken together, the study concludes that boron at physiological concentration induces lymphocyte proliferation and increases the synthesis and secretion of pro-inflammatory mediators by the LPS-primed macrophages, more specifically the M1 macrophages, possibly acting through Toll-like receptor. The study implicates boron as a regulator of the immune and inflammatory reactions and macrophage polarization, thus playing an important role in augmenting host defense against infection, with possible role in cancer and other diseases.
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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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Sacchetti M, Macchi I, Tiezzi A, La Cava M, Massaro-Giordano G, Lambiase A. Pathophysiology of Corneal Dystrophies: From Cellular Genetic Alteration to Clinical Findings. J Cell Physiol 2015; 231:261-9. [DOI: 10.1002/jcp.25082] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 06/19/2015] [Indexed: 02/04/2023]
Affiliation(s)
- Marta Sacchetti
- Cornea and Ocular Surface Unit; Ospedale San Raffaele, IRCCS-Milan; Milano Italy
| | - Ilaria Macchi
- Department of Ophthalmology; University of Rome “Campus Bio-Medico”; Rome Italy
| | - Alessandro Tiezzi
- Section of Ophthalmology, Department of Sense Organs; University of Rome “Sapienza”; Rome Italy
| | - Maurizio La Cava
- Section of Ophthalmology, Department of Sense Organs; University of Rome “Sapienza”; Rome Italy
| | | | - Alessandro Lambiase
- Section of Ophthalmology, Department of Sense Organs; University of Rome “Sapienza”; Rome Italy
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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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Zhang J, Patel DV. The pathophysiology of Fuchs' endothelial dystrophy – A review of molecular and cellular insights. Exp Eye Res 2015; 130:97-105. [DOI: 10.1016/j.exer.2014.10.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 10/30/2014] [Accepted: 10/31/2014] [Indexed: 12/22/2022]
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Kao L, Azimov R, Abuladze N, Newman D, Kurtz I. Human SLC4A11-C functions as a DIDS-stimulatable H⁺(OH⁻) permeation pathway: partial correction of R109H mutant transport. Am J Physiol Cell Physiol 2014; 308:C176-88. [PMID: 25394471 DOI: 10.1152/ajpcell.00271.2014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The SLC4A11 gene mutations cause a variety of genetic corneal diseases, including congenital hereditary endothelial dystrophy 2 (CHED2), Harboyan syndrome, some cases of Fuchs' endothelial dystrophy (FECD), and possibly familial keratoconus. Three NH2-terminal variants of the human SLC4A11 gene, named SLC4A11-A, -B, and -C are known. The SLC4A11-B variant has been the focus of previous studies. Both the expression of the SLC4A11-C variant in the cornea and its functional properties have not been characterized, and therefore its potential pathophysiological role in corneal diseases remains to be explored. In the present study, we demonstrate that SLC4A11-C is the predominant SLC4A11 variant expressed in human corneal endothelial mRNA and that the transporter functions as an electrogenic H(+)(OH(-)) permeation pathway. Disulfonic stilbenes, including 4,4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS), 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonate (H2DIDS), and 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonate (SITS), which are known to bind covalently, increased SLC4A11-C-mediated H(+)(OH(-)) flux by 150-200% without having a significant effect in mock-transfected cells. Noncovalently interacting 4,4'-diaminostilbene-2,2'-disulfonate (DADS) was without effect. We tested the efficacy of DIDS on the functionally impaired R109H mutant (SLC4A11-C numbering) that causes CHED2. DIDS (1 mM) increased H(+)(OH(-)) flux through the mutant transporter by ∼40-90%. These studies provide a basis for future testing of more specific chemically modified dilsulfonic stilbenes as potential therapeutic agents to improve the functional impairment of specific SLC4A11 mutant transporters.
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Affiliation(s)
- Liyo Kao
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - Rustam Azimov
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - Natalia Abuladze
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - Debra Newman
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and Brain Research Institute, University of California Los Angeles, Los Angeles, California
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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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Biosynthetic and functional defects in newly identified SLC4A11 mutants and absence of COL8A2 mutations in Fuchs endothelial corneal dystrophy. J Hum Genet 2014; 59:444-53. [PMID: 25007886 DOI: 10.1038/jhg.2014.55] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 05/26/2014] [Accepted: 06/12/2014] [Indexed: 12/31/2022]
Abstract
Late-onset Fuchs endothelial corneal dystrophy (FECD) shows genetic heterogeneity. Identification of SLC4A11 as a candidate gene for congenital hereditary endothelial dystrophy with similar corneal endothelial defects as FECD and reduced mRNA expression of SLC4A11 in the endothelium of FECD cases suggested that this gene may also be involved in pathogenesis of FECD. Mutations in SLC4A11 give rise to SLC4A11 protein marked by retention in the endoplasmic reticulum as a result of mis-folding. We screened 45 sporadic late-onset, 4 early-onset FECD patients and an early-onset autosomal dominant FECD family. We identified three previously unreported missense mutations: c.719G>C (p.W240S), c.1519G>A (p.V507I) and c.1304C>T (p.T434I) in unrelated individuals. These SLC4A11 mutants, expressed in HEK293 cells, had defects in either their cell surface expression or functional activity (rate of osmotically driven water flux). SLC4A11 mutations contribute to 11% (5/45) of sporadic late-onset FECD in the cohort studied. COL8A2, which causes some cases of early-onset FECD, was also screened in this cohort. No mutations were identified in COL8A2, in neither the late-onset cohort nor the early-onset family, suggesting genetic heterogeneity in this FECD family.
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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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Cordat E, Reithmeier RA. Structure, Function, and Trafficking of SLC4 and SLC26 Anion Transporters. CURRENT TOPICS IN MEMBRANES 2014; 73:1-67. [DOI: 10.1016/b978-0-12-800223-0.00001-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Caliaperumal J, Colbourne F. Rehabilitation Improves Behavioral Recovery and Lessens Cell Death Without Affecting Iron, Ferritin, Transferrin, or Inflammation After Intracerebral Hemorrhage in Rats. Neurorehabil Neural Repair 2013; 28:395-404. [DOI: 10.1177/1545968313517758] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background. Rehabilitation aids recovery from stroke in animal models, including in intracerebral hemorrhage (ICH). Sometimes, rehabilitation lessens brain damage. Objective. We tested whether rehabilitation improves recovery and reduces perihematoma neuronal death. We also evaluated whether rehabilitation influences iron toxicity and inflammation, mediators of secondary degeneration after ICH. Methods. Rats were trained to retrieve food pellets in a staircase apparatus and later subjected to striatal ICH (via collagenase infusion). After 1 week, they were given either enriched rehabilitation (ER), including reach training with group housing and environmental enrichment, or control treatment (group housing). Rats in the first experiment were treated for 2 weeks, functionally assessed, and killed humanely at 1 month to determine brain levels of nonheme iron. A second experiment used a similar approach, except that animals were euthanized at 14 days to evaluate perihematoma neuronal death (FluoroJade), iron distribution (Perls), and astrocyte (GFAP) and microglia (Iba-1) activity. A third experiment measured levels of iron-binding proteins (ferritin and transferrin) at 14 days. Results. Striatal ICH caused functional impairments, which were significantly improved with ER. The ICH caused delayed perihematoma neuronal death, which ER significantly reduced. Hemispheric iron levels, the amount of iron-binding proteins, and perihematoma astrocytes and microglia numbers were significantly elevated after ICH (vs normal side) but were not affected by ER. Conclusions. Rehabilitation is an effective behavioral and neuroprotective strategy for ICH. Neither effect appears to stem from influencing iron toxicity or inflammation. Thus, additional work must identify underlying mechanisms to help further therapeutic gains.
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Vincent AL. Corneal dystrophies and genetics in the International Committee for Classification of Corneal Dystrophies era: a review. Clin Exp Ophthalmol 2013; 42:4-12. [PMID: 24433354 DOI: 10.1111/ceo.12149] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 06/06/2013] [Indexed: 02/02/2023]
Abstract
Many of the corneal dystrophies have now been genetically characterized, and a system was established in 2008 by The International Committee for Classification of Corneal Dystrophies (IC3D) in an attempt to standardize the nomenclature. IC3D provided a classification system whereby all dystrophies can be categorized on the basis of the underlying genetic knowledge. Since that time, further work has established even more phenotypic and allelic heterogeneity than anticipated, particular for Fuchs endothelial corneal dystrophy and posterior polymorphous dystrophy. Using genome-wide association studies, a number of genes are now implicated both in normal corneal quantitative traits, such as central corneal thickness, as well as in disease. There is also a trend towards functional characterization of the genetic variants involved to elucidate the pathophysiology of these entities. This review article will provide an overview of the knowledge to date, with an emphasis on findings since the IC3D classification was published in 2008.
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Affiliation(s)
- Andrea L Vincent
- Department of Ophthalmology, National Eye Centre, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
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37
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Vilas GL, Loganathan SK, Liu J, Riau AK, Young JD, Mehta JS, Vithana EN, Casey JR. Transmembrane water-flux through SLC4A11: a route defective in genetic corneal diseases. Hum Mol Genet 2013; 22:4579-90. [PMID: 23813972 PMCID: PMC3889808 DOI: 10.1093/hmg/ddt307] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Three genetic corneal dystrophies [congenital hereditary endothelial dystrophy type 2 (CHED2), Harboyan syndrome and Fuchs endothelial corneal dystrophy] arise from mutations of the SLC4a11 gene, which cause blindness from fluid accumulation in the corneal stroma. Selective transmembrane water conductance controls cell size, renal fluid reabsorption and cell division. All known water-channelling proteins belong to the major intrinsic protein family, exemplified by aquaporins (AQPs). Here we identified SLC4A11, a member of the solute carrier family 4 of bicarbonate transporters, as an unexpected addition to known transmembrane water movement facilitators. The rate of osmotic-gradient driven cell-swelling was monitored in Xenopus laevis oocytes and HEK293 cells, expressing human AQP1, NIP5;1 (a water channel protein from plant), hCNT3 (a human nucleoside transporter) and human SLC4A11. hCNT3-expressing cells swelled no faster than control cells, whereas SLC4A11-mediated water permeation at a rate about half that of some AQP proteins. SLC4A11-mediated water movement was: (i) similar to some AQPs in rate; (ii) uncoupled from solute-flux; (iii) inhibited by stilbene disulfonates (classical SLC4 inhibitors); (iv) inactivated in one CHED2 mutant (R125H). Localization of AQP1 and SLC4A11 in human and murine corneal (apical and basolateral, respectively) suggests a cooperative role in mediating trans-endothelial water reabsorption. Slc4a11(-/-) mice manifest corneal oedema and distorted endothelial cells, consistent with loss of a water-flux. Observed water-flux through SLC4A11 extends the repertoire of known water movement pathways and call for a re-examination of explanations for water movement in human tissues.
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Affiliation(s)
- Gonzalo L Vilas
- Membrane Protein Disease Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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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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Chen Y, Huang K, Nakatsu MN, Xue Z, Deng SX, Fan G. Identification of novel molecular markers through transcriptomic analysis in human fetal and adult corneal endothelial cells. Hum Mol Genet 2012; 22:1271-9. [PMID: 23257286 DOI: 10.1093/hmg/dds527] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The corneal endothelium is composed of a monolayer of corneal endothelial cells (CECs), which is essential for maintaining corneal transparency. To better characterize CECs in different developmental stages, we profiled mRNA transcriptomes in human fetal and adult corneal endothelium with the goal to identify novel molecular markers in these cells. By comparing CECs with 12 other tissue types, we identified 245 and 284 signature genes that are highly expressed in fetal and adult CECs, respectively. Functionally, these genes are enriched in pathways characteristic of CECs, including inorganic anion transmembrane transporter, extracellular matrix structural constituent and cyclin-dependent protein kinase inhibitor activity. Importantly, several of these genes are disease target genes in hereditary corneal dystrophies, consistent with their functional significance in CEC physiology. We also identified stage-specific markers associated with CEC development, such as specific members in the transforming growth factor beta and Wnt signaling pathways only expressed in fetal, but not in adult CECs. Lastly, by the immunohistochemistry of ocular tissues, we demonstrated the unique protein localization for Wnt5a, S100A4, S100A6 and IER3, the four novel markers for fetal and adult CECs. The identification of a new panel of stage-specific markers for CECs would be very useful for characterizing CECs derived from stem cells or ex vivo expansion for cell replacement therapy.
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Affiliation(s)
- Yinyin Chen
- Translational Center for Stem Cell Research, Tongji Hospital, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
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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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