ABSTRACT
Ciliary assembly, trafficking, and regulation are dependent on microtubules, but the mechanisms of ciliary assembly also require the actin cytoskeleton. Here, we dissect subcellular roles of actin in ciliogenesis by focusing on actin networks nucleated by the Arp2/3 complex in the powerful ciliary model, Chlamydomonas. We find the Arp2/3 complex is required for the initial stages of ciliary assembly when protein and membrane are in high demand, but cannot yet be supplied from the Golgi complex. We provide evidence for Arp2/3 complex-dependent clathrin-mediated endocytosis of ciliary proteins, an increase in endocytic activity upon induction of ciliary growth, and relocalization of plasma membrane proteins to newly formed cilia. Our data support a new model of ciliary protein and membrane trafficking during early ciliogenesis whereby proteins previously targeted to the plasma membrane are reclaimed by Arp2/3 complex-dependent clathrin-mediated endocytosis for initial ciliary assembly.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Figure 1 from the previous version was moved to supplemental figure 1a, and supplemental figure 1b was added.
Figure 2 from the previous version was moved to figure 4 in the new version, images were updated, and panels C-J were removed, panel K became the new panel K.
Figure 3 from the previous version became figure 5. Panels B-C are new data, panels D-E came from figure 4 in the new version.
Figure 4 from the previous version became figure 6 in the new version. Images were updated, and panels H-I were moved to another figure.
Figure 5 from the previous version became figure 1 in the new version.
Figure 6 in the previous version became figure 2 in the new version. Panels D-E were removed.
Figure 7 in the previous version was removed for a future publication. This figure contained the contributions from collaborators David Sept and Courtney M Schroeder, so they were removed from this paper with their consent.
Figure 8 in the previous version became figure 3 in the new version.
Figure 9 from the previous version was removed.
Figures 7–10 and supplemental figure 5 were added to the new version.
