Figure 1.

Primary cilium dynamics during the cell cycle

(A) During G1/S transition, vertebrate cells undergo ciliary resorption to allow centrosome duplication and centrosome function as a microtubule organizing center in M phase. The primary cilium is re-established in post-mitotic G1/G0 cells, with the basal body of the primary cilium formed from the mother centriole (MC). (B) Formation of primary cilium requires prior assembly of a centrosome appendage protein complex and transition zone proteins at the MC. Ciliogenesis is controlled by both negative (including AURKA) and positive regulatory factors, some of which also influence ciliary length. In this context, levels of CDK5 increase in the centrosome in post-mitotic cells, and activation of CDK5 by p25 and p35 leads to NDE1 phosphorylation. NDE1 phosphorylation allows recruitment of FBW7, which targets NDE1 for ubiquitin-dependent proteasomal degradation.