Transient localized accumulation of actin in Caenorhabditis elegans blastomeres with oriented asymmetric divisions.

During Caenorhabditis elegans embryogenesis, specific cells in the P1 lineage rotate their duplicated centrosome pair onto the anterior-posterior axis; this rotation is correlated with and necessary for a differential inheritance of cytoplasmic determinants in the daughter cells. Centrosome pair rotation is sensitive to inhibitors of actin and microtubule polymerization and may require microtubule attachment to a specific cortical site. We show that actin and the barbed-end binding protein, capping protein, transiently accumulate at this cortical site, possibly by assembly onto persistent remnants of previous cell divisions. Based on these observations, we propose a model for the molecular basis of centrosome rotation that is consistent with the dependence of rotation on actin filaments and microtubules.