Microtubule cold stability in supporting cells of the gerbil auditory sensory epithelium: correlation with tubulin post-translational modifications

Abstract

Sensory cells in the organ of Corti exhibit loose microtubule networks enriched in tyrosinated tubulin, whereas supporting cells have bundled microtubules containing post-translationally modified tubulin. The tubulin isoform distribution suggests that the microtubules in sensory cells are dynamic and those in supporting cells are stable. To test this, microtubule resistance to cold-induced depolymerization was examined by using immunocytochemical methods and antibodies to post-translationally modified tubulins. Microtubule labelling in cochleas perfused/immersed at room temperature was identical to that in previous studies of untreated cochleas. However, the microtubule patterns of perfused/immersed specimens were changed in cold-treated cochleas. Microtubules were no longer detected with antibodies to alpha- and tyrosinated tubulin in sensory cells from specimens exposed to cold, indicating their disassembly. Supporting cells in the same specimens showed almost total loss of detyrosinated and polyglutamylated tubulin in the middle and apical cochlear turns, and reduced labelling in the basal-most turn. Probing for alpha-, nontyrosinatable, acetylated and glycylated tubulin yielded decreased and sometimes patchy staining but these isoforms were observed even when detyrosinated and polyglutamylated tubulins were absent. The results indicate that sensory cells in the gerbil auditory sensory epithelium contain only cold-sensitive microtubules. In contrast, supporting cells possess a substantial subset of cold-stable microtubules, providing structural support to the vibratory sensory organ required for hearing.

Cytoskeletal changes in actin and microtubules underlie the developing surface mechanical properties of sensory and supporting cells in the mouse cochlea

“…6). Previous results have observed increases in microtubule stability upon acetylation (Bane et al, 2002;Hammond et al, 2008). Therefore, these results further the argument that post-translational modifications of microtubules might impart the stability necessary for maturing PC mechanical properties (Tolomeo and Holley, 1997).…”

“…Also, the fluorescence intensity of phalloidin increased gradually in OHCs from E16 to P5, suggesting an accumulation of actin in these cells. An antibody raised to acetylated tubulin was used to identify a subset of stable microtubules, as previous studies have shown a high correlation between microtubule stability and acetylation (Bane et al, 2002;Westermann and Weber, 2003). Immunofluorescence was found primarily in PCs and DCs in both the lumenal and basolateral surfaces of the sensory epithelium (Fig.…”

“…Interestingly, the kinocilium, a microtubule-dense structure in OHCs, was unaffected by nocodazole (Fig. 8A, arrowheads) possibly owing to acetylation (Bane et al, 2002;Hammond et al, 2008) and low protein turnover (Zhang et al, 2012).…”

The microtubule end-binding protein EB2 is a central regulator of microtubule reorganisation in apico-basal epithelial differentiation

“…By contrast, the majority of the microtubules in the hair cells are dynamic and free in the cytoplasm (Fig. 9Ai, iii) (Bane et al, 2002;Furness et al, 1990;Mogensen et al, 2002;Slepecky et al, 1995;Tucker et al, 1992). A distinct pattern of EB2 expression was evident in the organ of Corti with high expression of EB2 in all hair cells but very low level of expression in the supporting cells (Fig.…”

Mutations of Tubulin Glycylation Sites Reveal Cross-talk between the C Termini of α- and β-Tubulin and Affect the Ciliary Matrix in Tetrahymena

“…The polymodifications could specifically recruit MAPs for assembly and stabilization of the B-tubule. In vitro experiments showed that polyglutamylation is involved in the interaction between tubulin and MAPs (61,62), and a correlation between glycylation and microtubule cold stability has been established in gerbil cochlea (63), presumably involving cold MAPs (64).…”