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PLoS Genet. 2015 Mar 27;11(3):e1005137. doi: 10.1371/journal.pgen.1005137. eCollection 2015 Mar.

HOMER2, a stereociliary scaffolding protein, is essential for normal hearing in humans and mice.

Author information

1
Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology University of Iowa, Iowa City, Iowa, United States of America.
2
Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America.
3
Department of Otorhinolaryngology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands.
4
Austin Health, Department of Medicine, University of Melbourne, Melbourne, Australia.
5
Self-employed physician, Menlo Park, California, United States of America.
6
Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology University of Iowa, Iowa City, Iowa, United States of America; Interdepartmental PhD Program in Genetics, University of Iowa, Iowa City, Iowa, United States of America.

Abstract

Hereditary hearing loss is a clinically and genetically heterogeneous disorder. More than 80 genes have been implicated to date, and with the advent of targeted genomic enrichment and massively parallel sequencing (TGE+MPS) the rate of novel deafness-gene identification has accelerated. Here we report a family segregating post-lingual progressive autosomal dominant non-syndromic hearing loss (ADNSHL). After first excluding plausible variants in known deafness-causing genes using TGE+MPS, we completed whole exome sequencing in three hearing-impaired family members. Only a single variant, p.Arg185Pro in HOMER2, segregated with the hearing-loss phenotype in the extended family. This amino acid change alters a highly conserved residue in the coiled-coil domain of HOMER2 that is essential for protein multimerization and the HOMER2-CDC42 interaction. As a scaffolding protein, HOMER2 is involved in intracellular calcium homeostasis and cytoskeletal organization. Consistent with this function, we found robust expression in stereocilia of hair cells in the murine inner ear and observed that over-expression of mutant p.Pro185 HOMER2 mRNA causes anatomical changes of the inner ear and neuromasts in zebrafish embryos. Furthermore, mouse mutants homozygous for the targeted deletion of Homer2 present with early-onset rapidly progressive hearing loss. These data provide compelling evidence that HOMER2 is required for normal hearing and that its sequence alteration in humans leads to ADNSHL through a dominant-negative mode of action.

PMID:
25816005
PMCID:
PMC4376867
DOI:
10.1371/journal.pgen.1005137
[Indexed for MEDLINE]
Free PMC Article

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