Absence of plastin 1 causes abnormal maintenance of hair cell stereocilia and a moderate form of hearing loss in mice.
Bottom Line: Several actin-associated proteins are essential for stereocilia formation and maintenance, and their absence leads to deafness.Auditory hair cells developed normally in Pls1 KO, but in young adult animals, the stereocilia of inner hair cells were reduced in width and length.These results show that in contrast to other actin-bundling proteins such as espin, harmonin or Eps8, plastin 1 is dispensable for the initial formation of stereocilia.
Affiliation: Centre for Auditory Research, UCL Ear Institute, University College London, London, UK.Show MeSH
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Mentions: However, at adult stages, the stereocilia of IHCs of Pls1 KO mice showed striking morphological defects (Fig. 5 and Table 1). They were frequently thinner, unusually bent (Fig. 5B) and of variable length within the same row (Fig. 5D and 5E). Within the same bundle, a mixture of normal-looking and abnormal stereocilia was frequently observed. The longest row of stereocilia showed an average reduction in width of 10–20% and the minimum width of individual stereocilia in Pls1 KO IHCs (0.15 µm) was much reduced when compared with that in wt animals (0.32 µm). Some stereocilia were reduced in width along their entire length, whereas in others, the distal end of the stereocilium was noticeably thinner than the proximal end (see for example Fig. 5E). Although the mean height of the row of longest stereocilia was not significantly reduced at any age examined up to 4 months (Table 1), there was a noticeable variability in the length of the longest stereocilia within the bundles of individual IHCs, which became more apparent with age (compare Fig. 5B with Fig. 5D and E; see also Supplementary Material, Fig. S2). These data indicate that the absence of plastin 1 caused structural defects in IHC stereocilia that affected their width and length, and perhaps their rigidity.Table 1.
Affiliation: Centre for Auditory Research, UCL Ear Institute, University College London, London, UK.