Generation and Fates of Supernumerary Centrioles in Dividing Cells

Abstract

The centrosome is a subcellular organelle from which a cilium assembles. Since centrosomes function as spindle poles during mitosis, they have to be present as a pair in a cell. How the correct number of centrosomes is maintained in a cell has been a major issue in the fields of cell cycle and cancer biology. Centrioles, the core of centrosomes, assemble and segregate in close connection to the cell cycle. Abnormalities in centriole numbers are attributed to decoupling from cell cycle regulation. Interestingly, supernumerary centrioles are commonly observed in cancer cells. In this review, we discuss how supernumerary centrioles are generated in diverse cellular conditions. We also discuss how the cells cope with supernumerary centrioles during the cell cycle.

Keywords: cancer cells; cell cycle; centrosome; mitosis; supernumerary centrioles.

Fig. 1. Generation of supernumerary centrioles.

Centrioles in normal cells assemble and segregate at the S and M phases, respectively. Supernumerary centrioles are generated at different cell cycle stages, caused by diverse occasions, depending on the diverse responsible mechanisms, such as PLK4 overexpression, centriole over-elongation, PCM disintegration and cytokinesis failure.

Fig. 2. Fates of the supernumerary centrioles during the cell cycle.

The cells with supernumerary centrioles may be arrested at M phase, due to mitosis failure. In other occasion, the cells may form bipolar spindles with clustered centrioles and undergo mitosis. Finally, biologically inactive forms of supernumerary centrioles hardly affect cell cycle progression.