Abstract
Centrosomes, the main microtubule organizing centers (MTOCs) of metazoan cells, contain an older ‘mother’ and a younger ‘daughter’ centriole. Stem cells either inherit the mother or daughter centriole, providing a mechanism for biased delivery of cell fate determinants. However, the molecular mechanisms regulating centrosome asymmetry and biased centrosome segregation are unclear. Using 3D-Structured Illumination Microscopy (3D-SIM), we here identify a centrosome asymmetry switch in fly neural stem cells. We show that the mitotic kinase Polo and its substrate, the centriolar protein Centrobin (Cnb), relocalize from the mother to the forming daughter centriole in mitosis. Polo’s relocalization depends on both Centrobin and Wdr62, and compromising the switch perturbs biased interphase MTOC activity. We propose that this asymmetry switch is necessary to form molecular and functional asymmetric centrosomes and the neuroblast specific retention of the daughter centriole-containing centrosome. The centrosome asymmetry switch might also explain the differences in centrosome inheritance across stem cell systems.