Development of outer hair cells in Ames waltzer mice: mutation in protocadherin 15 affects development of cuticular plate and associated structures.
The Ames waltzer (av) mouse mutant harbors a mutation in the protocadherin 15 gene (Pcdh15) and is a model for deafness in Usher syndrome 1F and nonsyndromic deafness DFNB23. Mutation in Pcdh15 affects stereocilia morphogenesis and polarity. Disruptions of apical cellular components in outer hair cells have also been described in av mutants. Organization of stereocilia and cell polarization may be dependent on proper orientation of structural components residing in the apical portion of the cell during development. We used electron and immunofluorescent microscopy to examine structural maturation of outer hair cells in av3J mice with emphasis on the fonticulus, basal body/centriole complex, actin mesh, and the microtubule network during initiation of bundle organization, between embryonic day (E) 16.5 and postnatal day 5 (P5). We found major ultrastructural rearrangements near the hair cell surface in av3J mice. Earliest changes were in kinocilia, basal body, and stereocilia positioning and microtubule arrangement once the kinocilia had lateralized to the side of the cell (between E16.5 and postnatal day [P] 0, before cuticular plate formation and stereocilia elongation). By P0, the developing fonticulus in av mice appeared enlarged, with a normal vesicle density. Stereocilia bundle disorganization increased after P0, with disruptions of the actin mesh within the cuticular plate. These observations support the hypothesis that mutations in Pcdh15 in av3J mice adversely affect coordinated maturation of apical cell components, resulting in disturbed stereocilia bundle polarity in av mice.
Kikkawa
Yayoi S
YS
Department of Otolaryngology-Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9035, USA.
Pawlowski
Karen S
KS
Wright
Charles G
CG
Alagramam
Kumar N
KN
D000818:Animals; D000831:Animals, Newborn; D000070585:Cadherin Related Proteins; D015820:Cadherins / Q000235:genetics / Q000502:physiology*; D016022:Case-Control Studies; D005260:Female; D018072:Hair Cells, Auditory, Outer / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D009925:Organ of Corti / Q000254:growth & development / Q000648:ultrastructure; D011498:Protein Precursors / Q000235:genetics / Q000502:physiology*
C418976:CDHR15 protein, mouse; D000070585:Cadherin Related Proteins; D015820:Cadherins; D011498:Protein Precursors