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Title
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Clarin-1 gene transfer rescues auditory synaptopathy in model of Usher syndrome
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Author
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Abstract
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| Clarin-1, a tetraspan-like membrane protein defective in Usher syndrome type IIIA (USH3A), is essential for hair bundle morphogenesis in auditory hair cells. We report a new synaptic role for clarin-1 in mouse auditory hair cells elucidated by characterization of Clrn1 total (Clrn1(ex4-/-)) and postnatal hair cell-specific conditional (Clrn1(ex4fl/fl) Myo15-Cre(+/-)) knockout mice. Clrn1(ex4-/-) mice were profoundly deaf, whereas Clrn1(ex4fl/fl) Myo15-Cre(+/-) mice displayed progressive increases in hearing thresholds, with, initially, normal otoacoustic emissions and hair bundle morphology. Inner hair cell (IHC) patch-clamp recordings for the 2 mutant mice revealed defective exocytosis and a disorganization of synaptic F-actin and Ca(V)1.3 Ca2+ channels, indicative of a synaptopathy. Postsynaptic defects were also observed, with an abnormally broad distribution of AMPA receptors associated with a loss of afferent dendrites and defective electrically evoked auditory brainstem responses. Protein-protein interaction assays revealed interactions between clarin-1 and the synaptic Ca(V)1.3 Ca2+ channel complex via the Ca-V beta(2) auxiliary subunit and the PDZ domain-containing protein harmonin (defective in Usher syndrome type IC). Cochlear gene therapy in vivo, through adeno-associated virus-mediated Clrn1 transfer into hair cells, prevented the synaptic defects and durably improved hearing in Clrn1(ex4fl/fl) Myo15-Cre(+/-) mice. Our results identify clarin-1 as a key organizer of IHC ribbon synapses, and suggest new treatment possibilities for USH3A patients. |
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Language
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English
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Source (journal)
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The journal of clinical investigation. - New York, N.Y., 1924, currens
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Publication
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New York, N.Y.
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2018
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ISSN
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0021-9738
[print]
1558-8238
[online]
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DOI
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10.1172/JCI94351
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Volume/pages
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128
:8
(2018)
, p. 3382-3401
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ISI
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000440461500023
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Full text (Publisher's DOI)
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