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Absence of plastin 1 causes abnormal maintenance of hair cell stereocilia and a moderate form of hearing loss in mice.

Taylor R, Bullen A, Johnson SL, Grimm-Günter EM, Rivero F, Marcotti W, Forge A, Daudet N - Hum. Mol. Genet. (2014)

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.

View Article: PubMed Central - PubMed

Affiliation: Centre for Auditory Research, UCL Ear Institute, University College London, London, UK.

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Morphological defects of stereocilia in adult Pls1 KO mice. (A–E) Scanning electron micrographs of IHCs in wt and Pls1 KO mice. Compared with those of P30 wt littermates (arrowheads in A), the stereocilia of Pls1 KO mice show a reduced width and abnormal bending (arrows in B). Similar defects are visible at 8 weeks (C–E). Note that the same IHC can have a mixture of thin (arrow) and normal (arrowhead) stereocilia (D). A distal tapering is also visible in some of the stereocilia of Pls1 KO (arrows in E). (F–J) Scanning electron micrographs of OHCs in wt and Pls1 KO mice. (F and G) At P30, the stereocilia of OHCs were very much less affected than those of IHCs in Pls1 KO mice and looked normal. There was no evidence of reduced width or abnormal bendiness. (H) At 8 weeks, some defects such as fusion of neighbouring stereocilia (arrow) were occasionally visible. (I and J) At 12 weeks, the stereocilia of Pls1 KO OHCs exhibited increased fusion and defects in organization (arrows) compared with those of wt OHCs; both images were taken from the basal turn of the cochlea. Scale bars = 1 µm.
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DDU417F5: Morphological defects of stereocilia in adult Pls1 KO mice. (A–E) Scanning electron micrographs of IHCs in wt and Pls1 KO mice. Compared with those of P30 wt littermates (arrowheads in A), the stereocilia of Pls1 KO mice show a reduced width and abnormal bending (arrows in B). Similar defects are visible at 8 weeks (C–E). Note that the same IHC can have a mixture of thin (arrow) and normal (arrowhead) stereocilia (D). A distal tapering is also visible in some of the stereocilia of Pls1 KO (arrows in E). (F–J) Scanning electron micrographs of OHCs in wt and Pls1 KO mice. (F and G) At P30, the stereocilia of OHCs were very much less affected than those of IHCs in Pls1 KO mice and looked normal. There was no evidence of reduced width or abnormal bendiness. (H) At 8 weeks, some defects such as fusion of neighbouring stereocilia (arrow) were occasionally visible. (I and J) At 12 weeks, the stereocilia of Pls1 KO OHCs exhibited increased fusion and defects in organization (arrows) compared with those of wt OHCs; both images were taken from the basal turn of the cochlea. Scale bars = 1 µm.

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.


Absence of plastin 1 causes abnormal maintenance of hair cell stereocilia and a moderate form of hearing loss in mice.

Taylor R, Bullen A, Johnson SL, Grimm-Günter EM, Rivero F, Marcotti W, Forge A, Daudet N - Hum. Mol. Genet. (2014)

Morphological defects of stereocilia in adult Pls1 KO mice. (A–E) Scanning electron micrographs of IHCs in wt and Pls1 KO mice. Compared with those of P30 wt littermates (arrowheads in A), the stereocilia of Pls1 KO mice show a reduced width and abnormal bending (arrows in B). Similar defects are visible at 8 weeks (C–E). Note that the same IHC can have a mixture of thin (arrow) and normal (arrowhead) stereocilia (D). A distal tapering is also visible in some of the stereocilia of Pls1 KO (arrows in E). (F–J) Scanning electron micrographs of OHCs in wt and Pls1 KO mice. (F and G) At P30, the stereocilia of OHCs were very much less affected than those of IHCs in Pls1 KO mice and looked normal. There was no evidence of reduced width or abnormal bendiness. (H) At 8 weeks, some defects such as fusion of neighbouring stereocilia (arrow) were occasionally visible. (I and J) At 12 weeks, the stereocilia of Pls1 KO OHCs exhibited increased fusion and defects in organization (arrows) compared with those of wt OHCs; both images were taken from the basal turn of the cochlea. Scale bars = 1 µm.
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Related In: Results  -  Collection

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DDU417F5: Morphological defects of stereocilia in adult Pls1 KO mice. (A–E) Scanning electron micrographs of IHCs in wt and Pls1 KO mice. Compared with those of P30 wt littermates (arrowheads in A), the stereocilia of Pls1 KO mice show a reduced width and abnormal bending (arrows in B). Similar defects are visible at 8 weeks (C–E). Note that the same IHC can have a mixture of thin (arrow) and normal (arrowhead) stereocilia (D). A distal tapering is also visible in some of the stereocilia of Pls1 KO (arrows in E). (F–J) Scanning electron micrographs of OHCs in wt and Pls1 KO mice. (F and G) At P30, the stereocilia of OHCs were very much less affected than those of IHCs in Pls1 KO mice and looked normal. There was no evidence of reduced width or abnormal bendiness. (H) At 8 weeks, some defects such as fusion of neighbouring stereocilia (arrow) were occasionally visible. (I and J) At 12 weeks, the stereocilia of Pls1 KO OHCs exhibited increased fusion and defects in organization (arrows) compared with those of wt OHCs; both images were taken from the basal turn of the cochlea. Scale bars = 1 µm.
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.

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.

View Article: PubMed Central - PubMed

Affiliation: Centre for Auditory Research, UCL Ear Institute, University College London, London, UK.

Show MeSH
Related in: MedlinePlus