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
PA is a paid consultant for Arcadia Science
Footnotes
In Figure 1, Panels C, D, G, and H and are new. In Figure 2, panel C is new and panels B and D were switched. In Figure 5 panel C, data was added for Dynasore. In Figure 6 panel F, the full blot was added. Statistics were added for the data in figure 7D. In Figure8 panels D and E, data was normalized to better demonstrate the point of the figure. In supplemental figure 2B, the full blot was added. Supplemental Figure 3 is new. Statistics were added for supplemental Figure 4. Supplemental Figure 5 is new. For Supplemental figure 7, 2 additional trials were added so that statistics could be done for B and D. Supplemental Figure 8B was added. Additionally, text was added to address concerns of reviewers.
