Simple Method To Characterize the Ciliary Proteome of Multiciliated Cells

Motile cilia of multiciliated epithelial cells have important
roles
in animal development and cell homeostasis. Although several studies
have identified and reported proteins localized in this complex organelle
and the related immotile primary cilia from various cell types, it
is still challenging to isolate high quantities of ciliary proteins
for proteomic analysis. In this study, African clawed frog (Xenopus laevis) embryos, which have many multiciliated
cells in the epidermis, were treated with a simple ionic buffer to
identify 1009 proteins conserved across vertebrates; these proteins
were putatively localized in motile cilia. Using two ciliary proteome
databases, we confirmed that previously validated cilia-associated
proteins are highly enriched in our ciliary proteome. Proteins localized
at the transition zone and Ellis-van Creveld zone, which are distinct
regions at the base of cilia, near the junction with the apical cell
surface, were isolated using our method. Among the newly identified
ciliary proteins, we report that KRT17 may have an unrecognized function
in motile cilia. Hence, the method developed in this study would be
useful for understanding the ciliary proteome.