Cep78 is a new centriolar protein involved in Plk4-induced centriole overduplication

Centrioles are core components of centrosomes, the major microtubule-organizing centers of animal cells, and act as basal bodies for cilia formation. Control of centriole number is therefore crucial for genome stability and embryogenesis. Centriole duplication requires the serine/threonine protein kinase PLK4. Here, we identify Cep78 as a human centrosomal protein and a new interaction partner of PLK4. Cep78 is mainly a centriolar protein that localizes to the centriolar wall. Furthermore, we find that PLK4 binds to Cep78 through its N-terminal domain but that Cep78 is not an in vitro PLK4 substrate. Cep78 colocalizes with PLK4 at centrioles and is required for Plk4-induced centriole overduplication. Interestingly, upon depletion of Cep78, newly synthesized PLK4 is not localized to centrosomes. Our results suggest that the interaction between Cep78 and the N-terminal catalytic domain of PLK4 is a new and important element in the centrosome overduplication process.

Centriole duplication; Centrosome; Cep78; Plk4.