Invitation to Seminar Talk
“Towards a molecular understanding
of the Drosophila centrosome”
Jeroen Dobbelaere
IMP, Vienna
Host: Tobias Bollenbach
Most eukaryotes, except higher plants, have centrosomes, which serve as a MT-organising centre (MTOC).
Centrosomes consist of a pair of centrioles surrounded by pericentriolar material or PCM. Centrioles duplicate like
DNA once per cell cycle and the centrioles number is highly controlled to prevent the formation of multi-polar
spindles and initiation of uncontrolled cell division. In contrast, to the well-ordered centriole barrel, the PCM
forms a meshwork of proteins surrounding the centriole. The PCM is a very dynamic structure and remodels itself
in the frame of minutes. The PCM is the site of MT-nucleation and anchoring and therefore represents the
functional part of the centrosome.
I performed a genome-wide RNAi screen and identify most if not all centrosome components and regulators of
the fly centrosome. My screen identified 32 proteins required for core centrosomal processes. Performing
localisation studies, combined with an extensive secondary analysis, enabled me to group the newly identified
genes according to their role in centriole duplication, centrosome separation and PCM maturation. Thus, we are
now approaching a complete inventory of proteins required for centrosome function in flies.
The genome-wide screen identified Polo kinase and PCM component centrosomin (Cnn) as the only two
components that can totally abolish PCM formation when depleted. I showed that Cnn is specifically
phosphorylated in mitosis in a Polo-dependent manner. I identified the phosphorylation site Serine 567 as the key
target of Polo kinase to induce PCM formation. Further experiments showed that Cnn phosphorylation only
happens at centrioles. Finally, I showed that Polo activity is needed to induce and maintain a PCM of constant size.
Ectopic expression of active Polo is sufficient to drive PCM recruitment and MT-array formation. These experiment
will help our understanding of the underlying molecular mechanisms controlling centrosome behaviour and
function in health and disease.
Wednesday, February 2, 2011, 11:15 am
Seminar Room Mondi 3, Central building, 1st floor
Institute of Science and Technology Austria | Am Campus 1 | 3400 Klosterneuburg
www.ist.ac.at