Clarin-1 gene transfer rescues auditory synaptopathy in model of Usher syndrome

J Clin Invest. 2018 Aug 1;128(8):3382-3401. doi: 10.1172/JCI94351. Epub 2018 Jul 9.


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 (Clrn1ex4-/-) and postnatal hair cell-specific conditional (Clrn1ex4fl/fl Myo15-Cre+/-) knockout mice. Clrn1ex4-/- mice were profoundly deaf, whereas Clrn1ex4fl/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 CaV1.3 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 CaV1.3 Ca2+ channel complex via the Cavβ2 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 Clrn1ex4fl/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.

Keywords: Calcium channels; Gene therapy; Neuroscience; Synapses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channels, L-Type / genetics
  • Calcium Channels, L-Type / metabolism
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cell Cycle Proteins
  • Cytoskeletal Proteins
  • Dependovirus
  • Disease Models, Animal
  • Gene Transfer Techniques*
  • Genetic Therapy*
  • Hair Cells, Auditory / metabolism*
  • Hair Cells, Auditory / pathology
  • Humans
  • Membrane Proteins* / biosynthesis
  • Membrane Proteins* / genetics
  • Mice
  • Mice, Knockout
  • Receptors, AMPA / genetics
  • Receptors, AMPA / metabolism
  • Synapses* / genetics
  • Synapses* / metabolism
  • Synapses* / pathology
  • Usher Syndromes* / genetics
  • Usher Syndromes* / metabolism
  • Usher Syndromes* / pathology
  • Usher Syndromes* / therapy


  • Cacna1d protein, mouse
  • Calcium Channels, L-Type
  • Carrier Proteins
  • Cell Cycle Proteins
  • Clrn1 protein, mouse
  • Cytoskeletal Proteins
  • Membrane Proteins
  • Receptors, AMPA
  • Ush1c protein, mouse