Control of daughter centriole formation by the pericentriolar material

Abstract

Controlling the number of its centrioles is vital for the cell as supernumerary centrioles result in multipolar mitosis and genomic instability. Normally, just one daughter centriole forms on each mature (mother) centriole; however, a mother centriole can produce multiple daughters within a single cell cycle. The mechanisms that prevent centriole ‘overduplication’ are poorly understood. Here we use laser microsurgery to test the hypothesis that attachment of the daughter centriole to the wall of the mother inhibits formation of additional daughters. We show that physical removal of the daughter induces reduplication of the mother in Sarrested cells. Under conditions when multiple daughters simultaneously form on a single mother, all of these daughters must be removed to induce reduplication. Intriguingly, the number of daughter centrioles that form during reduplication does not always match the number of ablated daughter centrioles. We also find that exaggeration of the pericentriolar material (PCM) via overexpression of the PCM protein pericentrin in S-arrested CHO cells induces formation of numerous daughter centrioles. We propose that that the size of the PCM cloud associated with the mother centriole restricts the number of daughters that can form simultaneously.