Poster Sessions

CB -8

Mi Hye Song

M. H. Song, A. Iyer, T. Müller-Reichert, K. O'Connell

The RNA-Binding Protein SZY-20 and the Kinase ZYG-1 Function Antagonistically to Determine Centrosome Size

The microtubule cytoskeleton is organized by the centrosome, a dynamic organelle that exhibits changes in both size and number during the cell cycle. The centrosome of a given cell type has a characteristic size but how the centrosome size is determined remains elucidated. We studied the C. elegans protein SZY-20, a novel, conserved RNA-binding protein that localizes at centrosomes and controls centrosome size. Depletion of SZY-20 results in centrosomes with increased levels of centrosome components while the centriole structure is unaltered. These enlarged centrosomes nucleate more microtubules and fail to properly direct microtubule-related processes. Depletion of ZYG-1, a centriole replication factor, restores normal centrosome size and function to szy-20 mutants while loss of SZY-20 suppresses the centrosome duplication defects in both zyg-1 and spd-2 mutants. Finally, we show that SAS-6, a downstream effector in the centriole replication pathway, also influences centrosome size. Our work thus identifies a new function for centriole replication factors and provides insight into a molecular mechanism by which the centrosome size is regulated.