Expression of acetylated tubulin in the postnatal developing mouse cochlea

Abstract

Microtubules are an essential component of the cytoskeleton of a eukaryotic cell. The post-translational tubulin modifications play an important role in regulating microtubule properties, acetylation tubulin is one of the major post-translational modifications of microtubules. Acetylation tubulin has also been shown to be expressed in the cochlea. However, the detailed expression profiles of acetylation tubulin protein during development have not yet been investigated in the postnatal mammalian cochlea. Here, we first examined the spatio-temporal expression of acetylated tubulin in the mouse cochlea during postnatal development. At postnatal day 1 (P1), acetylated tubulin was localized primarily to the auditory nerve inside the cochlea and their synaptic contacts with the inner and outer hair cells (IHCs and OHCs). In the organ of Corti, acetylated tubulin occurred first at the apex of pillar cells. At P5, acetylated tubulin first appeared in the phalangeal processes of Deiters’ cells. At P8, staining was maintained in the phalangeal processes of Deiters’ cells and neural elements. At P10, labeling in Deiters’ cells extended from the apices of OHCs to the basilar membrane, acetylated tubulin was expressed throughout the cytoplasm of inner and outer pillar cells. At P12, acetylated tubulin displayed prominent and homogeneous labeling along the full length of the pillar cells. Linear labeling was present mainly in the Deiters’ cell bodies underlying OHCs. Between P14 and P17, acetylated tubulin was strongly expressed in inner and outer pillar cells and Deiters’ cells in a similar pattern as observed in the adult, and labeling in these cells were arranged in bundles. In addition, acetylated tubulin was expressed in stria vascularis, root cell bodies, and a small number of fibrocytes of the spiral ligament until the adult. In the adult mouse cochlea, immunostaining continued to predominate in Deiters’ cells and pillar cells. In Deiters’ cells, immunolabeling formed cups securing OHCs basal portions, and continued presence of acetylated tubulin-labeled nerve terminals below IHCs was shown. Our results presented here underscored the essential role played by acetylated tubulin in postnatal cochlear development, auditory neurotransmission and cochlear mechanics.

Dispensability of Tubulin Acetylation for 15-protofilament Microtubule Formation in the Mammalian Cochlea

“…In the zebrafish model, the inhibition of this enzyme leads to developmental defects such as shortening of the body, neuromuscular defects, or reduction of eye and head size (Akella et al, 2010). Furthermore, abundant numbers of acetylated microtubules were reported in the cochlea in pillar and Deiter's cells (Li and Yang, 2015;Szarama et al, 2012;Tannenbaum and Slepecky, 1997) as observed in our immunofluorescence labeling for acetylated tubulin, and ATAT1 as the enzyme responsible for the acetylation of the tubulin in mice (Kalebic et al, 2013;Liu et al, 2018;Shida et al, 2010). We observed the disappearance of the acetylated microtubules in the pillar cells of the Atat1 KO mice, confirming the hypothesis that this enzyme is responsible of the acetylation of the microtubules present in pillar cells.…”

Characterizing Adult Cochlear Supporting Cell Transcriptional Diversity Using Single-Cell RNA-Seq: Validation in the Adult Mouse and Translational Implications for the Adult Human Cochlea

“…Since these regional distinctions could also be indicative of lineage restrictions, the identification of markers that define each domain could be utilized to create gene therapy targeting vectors specific for medial or lateral SC types (Stone and Cotanche, 2007;Cox et al, 2014). Comparison to existing adult SC (Liu W. J. et al, 2018;Ranum et al, 2019) and HC (Liu H. et al, 2014;Ranum et al, 2019) datasets has been provided as Supplementary Figures S14-S24 (Supplemental Datasheet S2).…”

High-throughput screening on cochlear organoids identifies VEGFR-MEK-TGFB1 signaling promoting hair cell reprogramming

“…Hair cell stereocilia, which are essential for hair cell mechano-transduction ( Fettiplace and Hackney, 2006 ), also showed gradual elongation during organoid differentiation ( Figures 1 J–1L). Importantly, the kinocilia, developmental structures present in immature but not mature cochlear hair cells ( Liu et al., 2018b ), were gradually lost by DIV24 and DIV26 ( Figures 1 J, 1K, and 1M). These findings indicate that expansion and differentiation of the cochlear organoids is highly efficient, and hair cells differentiated within the organoids show developmental maturation.…”