| Тойм: | Mitotic centrosomes are formed when centrioles start to recruit large amounts of
pericentriolar material (PCM) around themselves in preparation for mitosis. This
centrosome “maturation” requires the centrioles and also Polo/PLK1 protein kinase. The
PCM comprises several hundred proteins and, in Drosophila, Polo cooperates with the
conserved centrosome proteins Spd-2/CEP192 and Cnn/CDK5RAP2 to assemble a PCM
scaffold around the mother centriole that then recruits other PCM client proteins. We show
here that in Drosophila syncytial blastoderm embryos, centrosomal Polo levels rise and
fall during the assembly process—peaking, and then starting to decline, even as levels of
the PCM scaffold continue to rise and plateau. Experiments and mathematical modelling
indicate that a centriolar pulse of Polo activity, potentially generated by the interaction
between Polo and its centriole receptor Ana1 (CEP295 in humans), could explain these
unexpected scaffold assembly dynamics. We propose that centrioles generate a local
pulse of Polo activity prior to mitotic entry to initiate centrosome maturation, explaining
why centrioles and Polo/PLK1 are normally essential for this process.
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