Centrosomes are cytoplasmic organelles in animal cells whose primary function is to organize the microtubule cytoskeleton. As such, they contribute to organelle positioning, cellular trafficking, and cell division. Consistent with their central role in cellular architecture, defects in centrosome number and structure have been linked to a variety of human disorders, including cancer, microcephaly and dwarfism. Centrosome abnormalities are particularly prevalent in solid tumors as well as hematological malignancies, where they are associated with poor prognosis. Centrosomes are formed by the recruitment of microtubule-organizing pericentriolar material (PCM) to a pair of centrioles whose duplication once per cell cycle ensures the formation of a bipolar spindle during cell division. While the molecular pathways underlying centriole duplication have become much clearer in recent years, the nature of the pericentriolar material and how it is recruited to centrioles remains largely unknown.
Classical experiments have revealed the existence of a filamentous matrix within the pericentriolar material that serves as a scaffold for the recruitment of other proteins that nucleate and anchor microtubules. The molecular composition of this scaffold, thought to be central to centrosome assembly, has not been determined. In this project I will combine biochemical and cell biological approaches to characterize the pericentriolar matrix at a molecular level. The proposed work is divided into two complementary aims. First, I will isolate and extract centrosomes from Drosophila and C. elegans embryos and use mass spectrometry to determine the molecular composition of the salt-insoluble pericentriolar matrix. Second I will use proximity-dependent labeling to study protein-protein interactions across the centriole-pericentriolar material interface. Candidate proteins and protein interactions will be further investigated by high-resolution microscopy in live embryos.
The approaches briefly outlined above aim to capitalize on the advantages of Drosophila melanogaster and C. elegans as experimental models to investigate the fundamental and conserved molecular mechanisms underlying centrosome assembly. Successful completion of this work should further our understanding of these cellular structures, which are of key relevance to human development and disease.