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Nyegaard M, Rendtorff ND, Nielsen MS, Corydon TJ, Demontis D, Starnawska A, Hedemand A, Buniello A, Niola F, Overgaard MT, Leal SM, Ahmad W, Wikman FP, Petersen KB, Crüger DG, Oostrik J, Kremer H, Tommerup N, Frödin M, Steel KP, Tranebjærg L, Børglum AD. A Novel Locus Harbouring a Functional CD164 Nonsense Mutation Identified in a Large Danish Family with Nonsyndromic Hearing Impairment. PLoS Genet 2015. [PMID: 26197441 PMCID: PMC4510537 DOI: 10.1371/journal.pgen.1005386] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Nonsyndromic hearing impairment (NSHI) is a highly heterogeneous condition with more than eighty known causative genes. However, in the clinical setting, a large number of NSHI families have unexplained etiology, suggesting that there are many more genes to be identified. In this study we used SNP-based linkage analysis and follow up microsatellite markers to identify a novel locus (DFNA66) on chromosome 6q15-21 (LOD 5.1) in a large Danish family with dominantly inherited NSHI. By locus specific capture and next-generation sequencing, we identified a c.574C>T heterozygous nonsense mutation (p.R192*) in CD164. This gene encodes a 197 amino acid transmembrane sialomucin (known as endolyn, MUC-24 or CD164), which is widely expressed and involved in cell adhesion and migration. The mutation segregated with the phenotype and was absent in 1200 Danish control individuals and in databases with whole-genome and exome sequence data. The predicted effect of the mutation was a truncation of the last six C-terminal residues of the cytoplasmic tail of CD164, including a highly conserved canonical sorting motif (YXXФ). In whole blood from an affected individual, we found by RT-PCR both the wild-type and the mutated transcript suggesting that the mutant transcript escapes nonsense mediated decay. Functional studies in HEK cells demonstrated that the truncated protein was almost completely retained on the plasma cell membrane in contrast to the wild-type protein, which targeted primarily to the endo-lysosomal compartments, implicating failed endocytosis as a possible disease mechanism. In the mouse ear, we found CD164 expressed in the inner and outer hair cells of the organ of Corti, as well as in other locations in the cochlear duct. In conclusion, we have identified a new DFNA locus located on chromosome 6q15-21 and implicated CD164 as a novel gene for hearing impairment.
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Affiliation(s)
- Mette Nyegaard
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Integrative Sequencing (iSEQ), Aarhus University, Aarhus, Denmark
- * E-mail:
| | - Nanna D. Rendtorff
- Wilhelm Johannsen Centre for Functional Genome Research, Department of Cellular and Molecular Medicine (ICMM), The Panum Institute, University of Copenhagen, Copenhagen, Denmark
- Department of Otorhinolaryngology, Head & Neck Surgery and Audiology, Bispebjerg Hospital/Rigshospitalet, Copenhagen, Denmark
- Clinical Genetic Clinic, Kennedy Center, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | | | | | - Ditte Demontis
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Integrative Sequencing (iSEQ), Aarhus University, Aarhus, Denmark
| | - Anna Starnawska
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Integrative Sequencing (iSEQ), Aarhus University, Aarhus, Denmark
| | - Anne Hedemand
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Integrative Sequencing (iSEQ), Aarhus University, Aarhus, Denmark
| | - Annalisa Buniello
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Francesco Niola
- Biotech Research & Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | | | - Suzanne M. Leal
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Friedrik P. Wikman
- Department of Molecular Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark
| | | | | | - Jaap Oostrik
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, Nijmegen, Netherlands
| | - Hannie Kremer
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, Nijmegen, Netherlands
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Nijmegen, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Nijmegen, Netherlands
| | - Niels Tommerup
- Wilhelm Johannsen Centre for Functional Genome Research, Department of Cellular and Molecular Medicine (ICMM), The Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Morten Frödin
- Biotech Research & Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Karen P. Steel
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Lisbeth Tranebjærg
- Wilhelm Johannsen Centre for Functional Genome Research, Department of Cellular and Molecular Medicine (ICMM), The Panum Institute, University of Copenhagen, Copenhagen, Denmark
- Department of Otorhinolaryngology, Head & Neck Surgery and Audiology, Bispebjerg Hospital/Rigshospitalet, Copenhagen, Denmark
- Clinical Genetic Clinic, Kennedy Center, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | - Anders D. Børglum
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Integrative Sequencing (iSEQ), Aarhus University, Aarhus, Denmark
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Mo D, Costa SA, Ihrke G, Youker RT, Pastor-Soler N, Hughey RP, Weisz OA. Sialylation of N-linked glycans mediates apical delivery of endolyn in MDCK cells via a galectin-9-dependent mechanism. Mol Biol Cell 2012; 23:3636-46. [PMID: 22855528 PMCID: PMC3442411 DOI: 10.1091/mbc.e12-04-0329] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The sialomucin endolyn is implicated in adhesion, migration, and differentiation of various cell types. Apical delivery of endolyn requires recognition of sialic acids on its N-glycans possibly (or likely) mediated by galectin-9. The sialomucin endolyn is implicated in adhesion, migration, and differentiation of various cell types. Along rat kidney tubules, endolyn is variously localized to the apical surface and endosomal/lysosomal compartments. Apical delivery of newly synthesized rat endolyn predominates over direct lysosomal delivery in polarized Madin–Darby canine kidney cells. Apical sorting depends on terminal processing of a subset of lumenal N-glycans. Here we dissect the requirements of N-glycan processing for apical targeting and investigate the underlying mechanism. Modulation of glycan branching and subsequent polylactosamine elongation by knockdown of N-acetylglucosaminyltransferase III or V had no effect on apical delivery of endolyn. In contrast, combined but not individual knockdown of sialyltransferases ST3Gal-III, ST3Gal-IV, and ST6Gal-I, which together are responsible for addition of α2,3- and α2,6-linked sialic acids on N-glycans, dramatically decreased endolyn surface polarity. Endolyn synthesized in the presence of kifunensine, which blocks terminal N-glycan processing, reduced its interaction with several recombinant canine galectins, and knockdown of galectin-9 (but not galectin-3, -4, or -8) selectively disrupted endolyn polarity. Our data suggest that sialylation enables recognition of endolyn by galectin-9 to mediate efficient apical sorting. They raise the intriguing possibility that changes in glycosyltransferase expression patterns and/or galectin-9 distribution may acutely modulate endolyn trafficking in the kidney.
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Affiliation(s)
- Di Mo
- Renal Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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