Dissecting the molecular function of PCMD-1 in PCM scaffold formation

• Applicant: Dr. Tamara Mikeladze-Dvali
• Subject Area: General Genetics and Functional Genome Biology ; Developmental Biology ; Cell Biology
• Term: since 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 251892086

Centrosomes, the major microtubule organizing centers of animal cells, are essential for the assembly of a bipolar spindle during mitosis. Centrosomes comprise a pair of centrioles and the surrounding pericentriolar material (PCM). The PCM forms a thin shell (PCM core) around non-mitotic centrioles. At mitotic entry the PCM expands to enable robust microtubule nucleation and spindle formation. Recently we identified the novel C. elegans protein PeriCentriolar Matrix Deficient-1 (PCMD-1), and demonstrated that PCMD-1 is necessary for the formation of the non-mitotic PCM core. PCMD-1 facilitates efficient loading of the scaffold protein Spindle Defective-5 (SPD-5), its partner SPD-2 and the mitotic kinase Polo-like-kinase 1 (PLK-1) to the PCM core. Furthermore, the absence of PCMD-1 disrupts mitotic PCM recruitment and integrity. Our preliminary data strongly suggest that PCMD-1 acts as a molecular linker between the PCM and the centrioles. Therefore, PCMD-1 represents the first centrosomal linker protein in C. elegans. However, how PCMD-1 mediates this molecular function and how PCMD-1 itself is regulated remain open questions. Here we propose to use protein-protein interaction assays in combination with different live-cell imaging assays to delineate mechanisms of PCMD-1 interactions with PCM proteins and mitotic regulators, in particular SPD-5 and PLK-1. Further, we propose to analyze dynamic properties of the PCM scaffold in the absence of PCMD-1. Finally, to understand how PCMD-1 itself is regulated and how it regulates the PCM scaffold, we propose to perform structure-functional analysis of PCMD-1.In summary, our work will uncover the molecular function of PCMD-1 as a centrosomal linker protein and the biological function of the PCM core for bipolar spindle formation.

• DFG Programme: Research Grants