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. Author manuscript; available in PMC: 2016 Oct 25.
Published in final edited form as: Nat Cell Biol. 2016 Jun 28;18(7):711–717. doi: 10.1038/ncb3370

Figure 3. Cilium disassembly.

Figure 3

Serum growth factors trigger cilium disassembly in G1 phase through the concerted actions of two kinesins (Kif2a and Kif24) and destabilization of acetylated tubulins in the ciliary axoneme. The initiation of ciliary disassembly in early G1 requires the inhibition of axoneme extension (Plk1/Kif2a) and recruitment and activation of AurA/HEF1, which activates HDAC6 (H, green circles) and tubulin de-acetylation; this, in turn, leads to disassembly (steps I–III). Pitchfork (Pifo) and trichoplein collaborate to activate AurA, and Ndel1 stabilizes trichoplein at basal bodies to suppress ciliogenesis. Plk1-mediated phosphorylation of Kif2a stimulates its ability to depolymerize axonemal microtubules shortly after mitogen stimulation. At a later point, Nek2 is expressed and associates with Kif24, phosphorylating and activating this second de-polymerizing kinesin. Activation of Kif24 provides a sustained block to re-ciliation throughout S/G2/M (step IV), thereby ensuring that centrioles remain competent to replicate in S phase and assemble a mitotic spindle in M phase.