RNA localization to the mitotic spindle regulated by kinesin-1 and dynein is essential for early development of the sea urchin embryo

Mitosis is a fundamental and highly regulated process that acts to faithfully segregate chromosomes into two identical daughter cells. Transcript localization of genes involved in mitosis to the mitotic spindle may be an evolutionarily conserved mechanism to ensure that mitosis occurs in a timely manner. We identified many RNA transcripts that encode proteins involved in mitosis localized at the mitotic spindles in dividing sea urchin embryos and mammalian cells. Disruption of microtubule polymerization, kinesin-1, or dynein results in lack of spindle localization of these transcripts in the sea urchin embryo. Further, results indicate that the cytoplasmic polyadenylation element (CPE) within the 3UTR of Aurora B, a recognition sequence of CPEB, is essential for RNA localization to the mitotic spindle. Blocking this sequence results in arrested development during early cleavage stages, suggesting that RNA localization to the mitotic spindle may be a regulatory mechanism of cell division that is important for early development.