title: The CD2 isoform of protocadherin-15 is an essential component of the tip-link complex in mature auditory hair cells.
abstract: Protocadherin-15 (Pcdh15) is a component of the tip-links, the extracellular filaments that gate hair cell mechano-electrical transduction channels in the inner ear. There are three Pcdh15 splice isoforms (CD1, CD2 and CD3), which only differ by their cytoplasmic domains; they are thought to function redundantly in mechano-electrical transduction during hair-bundle development, but whether any of these isoforms composes the tip-link in mature hair cells remains unknown. By immunolabelling and both morphological and electrophysiological analyses of post-natal hair cell-specific conditional knockout mice (Pcdh15ex38-fl/ex38-fl Myo15-cre+/-) that lose only this isoform after normal hair-bundle development, we show that Pcdh15-CD2 is an essential component of tip-links in mature auditory hair cells. The finding, in the homozygous or compound heterozygous state, of a PCDH15 frameshift mutation (p.P1515Tfs*4) that affects only Pcdh15-CD2, in profoundly deaf children from two unrelated families, extends this conclusion to humans. These results provide key information for identification of new components of the mature auditory mechano-electrical transduction machinery. This will also serve as a basis for the development of gene therapy for deafness caused by PCDH15 defects.
authors.affiliation: Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France Université Pierre et Marie Curie (Paris VI), Paris, France.
authors.forename: Elise
authors.initials: E
authors.lastname: Pepermans
authors.affiliation: Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France Université Pierre et Marie Curie (Paris VI), Paris, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Michel
authors.affiliation: School of Life Sciences, University of Sussex, Brighton, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Goodyear
authors.affiliation: UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France Université Pierre et Marie Curie (Paris VI), Paris, France Syndrome de Usher et autres Atteintes Rétino-Cochléaires, Institut de la vision, Paris, France.
authors.forename: Crystel
authors.initials: C
authors.lastname: Bonnet
authors.affiliation: Centre Hospitalier universitaire de Blida, Université Saad Dahleb, Blida, Algérie.
authors.forename: Samia
authors.initials: S
authors.lastname: Abdi
authors.affiliation: Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France Université Pierre et Marie Curie (Paris VI), Paris, France.
authors.forename: Typhaine
authors.initials: T
authors.lastname: Dupont
authors.affiliation: Centre de référence des Surdités Génétiques, Hôpital Necker, Paris, France.
authors.forename: Souad
authors.initials: S
authors.lastname: Gherbi
authors.affiliation: Service de Génétique Clinique, Hôpital Jeanne-de-Flandre, Lille, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Holder
authors.affiliation: Laboratoire de Biochimie Génétique, Université d'Alger 1, Alger, Algérie.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Makrelouf
authors.affiliation: Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France Université Pierre et Marie Curie (Paris VI), Paris, France.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hardelin
authors.affiliation: Centre de référence des Surdités Génétiques, Hôpital Necker, Paris, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Marlin
authors.affiliation: Laboratoire de Biochimie Génétique, Université d'Alger 1, Alger, Algérie.
authors.forename: Akila
authors.initials: A
authors.lastname: Zenati
authors.affiliation: School of Life Sciences, University of Sussex, Brighton, UK.
authors.forename: Guy
authors.initials: G
authors.lastname: Richardson
authors.affiliation: Laboratoire de Biophysique Sensorielle, Université d'Auvergne, Clermont-Ferrand, France UMR 1107, Institut National de la Santé et de la Recherche Médicale (INSERM), Clermont-Ferrand, France Centre Jean Perrin, Clermont-Ferrand Cedex 01, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Avan
authors.affiliation: Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France Université Pierre et Marie Curie (Paris VI), Paris, France.
authors.forename: Amel
authors.initials: A
authors.lastname: Bahloul
authors.affiliation: Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France Université Pierre et Marie Curie (Paris VI), Paris, France Syndrome de Usher et autres Atteintes Rétino-Cochléaires, Institut de la vision, Paris, France Collège de France, Paris, France cpetit@pasteur.fr.
authors.forename: Christine
authors.initials: C
authors.lastname: Petit
mesh_terms: D000818:Animals; D000070585:Cadherin Related Proteins; D015820:Cadherins / Q000032:analysis / Q000235:genetics*; D002648:Child; D003638:Deafness / Q000235:genetics*; D005260:Female; D016368:Frameshift Mutation; D006198:Hair Cells, Auditory / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008297:Male; D040542:Mechanotransduction, Cellular; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D020033:Protein Isoforms / Q000032:analysis / Q000235:genetics; D011498:Protein Precursors / Q000032:analysis / Q000235:genetics*
chemical_list: C418976:CDHR15 protein, mouse; C498835:CDHR15, human; D000070585:Cadherin Related Proteins; D015820:Cadherins; D020033:Protein Isoforms; D011498:Protein Precursors
keywords: auditory mechano‐electrical transduction; deafness; protocadherin‐15; stereocilia; tip‐link