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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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Organization of the actin filaments in the stereocilia of Pls1 KO mice. (A and B) Transmission electron micrographs of the top and shaft region of the IHC stereocilia in adult (4 month and older) het and Pls1 KO mice. (C) Mean values of the interfilament distance within the stereocilia of het and Pls1 KO mice. Mean values are shown for all measurements, and those obtained from either the shaft or the top region (within 300 nm of the tip) only; 250 measurements were taken from 5 different stereocilia for each genotype; error bars represent the standard error of the mean. The interfilament distance was significantly increased in the top region of stereocilia of Pls1 KO mice compared with het mice (P-value = 0.004; unpaired T-test with Welch's Correction).
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DDU417F6: Organization of the actin filaments in the stereocilia of Pls1 KO mice. (A and B) Transmission electron micrographs of the top and shaft region of the IHC stereocilia in adult (4 month and older) het and Pls1 KO mice. (C) Mean values of the interfilament distance within the stereocilia of het and Pls1 KO mice. Mean values are shown for all measurements, and those obtained from either the shaft or the top region (within 300 nm of the tip) only; 250 measurements were taken from 5 different stereocilia for each genotype; error bars represent the standard error of the mean. The interfilament distance was significantly increased in the top region of stereocilia of Pls1 KO mice compared with het mice (P-value = 0.004; unpaired T-test with Welch's Correction).

Mentions: To determine whether the absence of plastin 1 might affect the structural organization of the parallel actin bundles within stereocilia, high-resolution images of thin sections of IHCs stereocilia from adult het and Pls1 KO mice were collected (Fig. 6A and B). The mean distance between actin filaments was measured (Fig. 6C) at two different levels of stereocilia: the top region (within 300 nm of the tip) and the shaft region located more basally. At the level of the shaft, there was no significant difference in the packing density of actin filaments in abnormal-looking stereocilia of Pls1 KO (mean = 8.628 nm, SD = 2.36; n = 250 measurements) compared with het (mean = 8.644 nm, SD = 2.154; n = 250) samples. This suggests that the reduction in width of IHC stereocilia is primarily due to a reduction in the number of actin filaments they contain and not to drastic changes in their packing. In the top region, however, the interfilament distance was slightly but significantly (P < 0.05) increased in Pls1 KO (mean = 9.638 nm, SD = 1.851; n = 250, five stereocilia) compared with het (mean = 9.134 nm, SD = 2.049; n = 250, five stereocilia) samples, suggesting that plastin 1 may have a particular importance for F-actin crosslinking at this site, where the plus end of actin filaments is located.Figure 6.


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)

Organization of the actin filaments in the stereocilia of Pls1 KO mice. (A and B) Transmission electron micrographs of the top and shaft region of the IHC stereocilia in adult (4 month and older) het and Pls1 KO mice. (C) Mean values of the interfilament distance within the stereocilia of het and Pls1 KO mice. Mean values are shown for all measurements, and those obtained from either the shaft or the top region (within 300 nm of the tip) only; 250 measurements were taken from 5 different stereocilia for each genotype; error bars represent the standard error of the mean. The interfilament distance was significantly increased in the top region of stereocilia of Pls1 KO mice compared with het mice (P-value = 0.004; unpaired T-test with Welch's Correction).
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Related In: Results  -  Collection

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DDU417F6: Organization of the actin filaments in the stereocilia of Pls1 KO mice. (A and B) Transmission electron micrographs of the top and shaft region of the IHC stereocilia in adult (4 month and older) het and Pls1 KO mice. (C) Mean values of the interfilament distance within the stereocilia of het and Pls1 KO mice. Mean values are shown for all measurements, and those obtained from either the shaft or the top region (within 300 nm of the tip) only; 250 measurements were taken from 5 different stereocilia for each genotype; error bars represent the standard error of the mean. The interfilament distance was significantly increased in the top region of stereocilia of Pls1 KO mice compared with het mice (P-value = 0.004; unpaired T-test with Welch's Correction).
Mentions: To determine whether the absence of plastin 1 might affect the structural organization of the parallel actin bundles within stereocilia, high-resolution images of thin sections of IHCs stereocilia from adult het and Pls1 KO mice were collected (Fig. 6A and B). The mean distance between actin filaments was measured (Fig. 6C) at two different levels of stereocilia: the top region (within 300 nm of the tip) and the shaft region located more basally. At the level of the shaft, there was no significant difference in the packing density of actin filaments in abnormal-looking stereocilia of Pls1 KO (mean = 8.628 nm, SD = 2.36; n = 250 measurements) compared with het (mean = 8.644 nm, SD = 2.154; n = 250) samples. This suggests that the reduction in width of IHC stereocilia is primarily due to a reduction in the number of actin filaments they contain and not to drastic changes in their packing. In the top region, however, the interfilament distance was slightly but significantly (P < 0.05) increased in Pls1 KO (mean = 9.638 nm, SD = 1.851; n = 250, five stereocilia) compared with het (mean = 9.134 nm, SD = 2.049; n = 250, five stereocilia) samples, suggesting that plastin 1 may have a particular importance for F-actin crosslinking at this site, where the plus end of actin filaments is located.Figure 6.

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