Control of centrosome reproduction: The right number at the right time

It is of great importance for the cell to precisely coordinate the doubling of the interphase centrosome with nuclear events during the cell cycle and limit the number of centrosomes it contains at the onset of mitosis to two and only two. The penalties for mistakes are abnormal spindle assembly, in appropriate chromosome distribution, and consequently, genomic instability. We review the functional properties of the mechanisms that control when th e centrosome duplicates in the cell cycle and the controls for centrosome c opy number. We look to limits that are intrinsic to the centrosome itself a nd controls imposed by cell cycle linked changes in cytoplasmic conditions. Control of centrosome reproduction is exercised at both levels. (C) 1999 E ditions scientifiques et medicales Elsevier SAS.