Ana1 recruits PLK1 to mother centrioles to promote mitotic PCM assembly and centriole elongation

Polo kinase (PLK1) is a master cell cycle regulator that is recruited to various subcellular structures by its Polo-Box domain (PBD), which binds to phosphorylated S-pS/pT motifs. Polo has multiple functions at centrioles and centrosomes, and we previously showed that phosphorylated Sas-4 initiates Polo recruitment to newly formed centrioles, while phosphorylated Spd-2 recruits Polo to the mitotic Pericentriolar Material (PCM) that assembles around mother centrioles. Here, we investigate whether additional proteins recruit Polo to centrioles and/or centrosomes, and find that Ana1 (Cep295 in mammals) helps recruit Polo to mother centrioles. If this function is impaired, mother centrioles can still duplicate and disengage from their daughters, but they can no longer efficiently assemble a mitotic PCM or elongate their centrioles in G2. Thus, Ana1 is part of a sequential phosphorylation cascade that recruits Polo to centrioles to drive mitotic centrosome assembly and centriole elongation in G2, but not centriole duplication or disengagement.