Xu, X.; Ross, J.; Clark, F.; Wei, S.; Sun, J.

Cilia are microtubule-based organelles found on the surface of most eukaryotic cells. These microtubules are composed of - and {beta}-tubulin heterodimers, and different tubulin isotypes can confer distinct properties to microtubules. Despite their importance, the contribution of individual tubulin isotype to cilia formation and function remains largely unexplored in vertebrates. Here, we identify a critical role for the {beta}-tubulin isotype Tubb6 in the formation of motile cilia in Xenopus epidermal multiciliated cells (MCCs). Tubb6 mRNA is selectively expressed in MCCs, and its protein product localizes to ciliary axonemes. Loss of Tubb6 leads to a marked reduction in cilia number and length, resulting in defective MCC function. In contrast, mono-motile cilia in the gastrocoel roof plate are unaffected by Tubb6 depletion, suggesting a selective requirement for ciliogenesis in MCCs. Together, our findings uncover a cell type-specific role for Tubb6 in motile cilia formation and highlight the functional specialization of tubulin isotypes in vertebrate cilia assembly.