[en] The auditory organ is a highly specialized structure composed by specific cellular types. The sensory cells are characterized by stereocilia at their apex and are necessary for the sound perception. These cells are supported by supporting cells. Supporting cells possess a characteristic cytoskeleton in direct relation with their morphological features and their development. There are different β-tubulin isoforms in microtubules of vertebrate tissues. However, their functional significance is still largely unknown.
In the present study, we investigated the localization of five β-tubulin isotypes (β 1 to 5) as well as acetyl-α-tubulin within the hearing organ during development in rodents. By using confocal microscopy, we showed that with the exception of the β3-tubulin isoform that was specific to nerve fibres, all the different β-tubulin isoforms and acetyl-α-tubulin were mainly present in the supporting cells. Contrary to β1-4-tubulins, we also found that the β5-tubulin isoform appeared only at a key stage of the postnatal development in specific cell types (pillar cells and Deiters’ cells). By using transmission electron microscopy, we revealed further that this developmental stage coincided with the formation of two separate bundles of microtubules from a unique one in these supporting cells. In conclusion, these results suggest that the β5-tubulin isoform might be involved in the generation of new microtubule bundles from a pre-existing one.
