Simultaneous Regulation of Cytokinetic Furrow and Nucleus Positions by Cortical Tension Contributes to Proper DNA...

Coordinating mitotic spindle and cytokinetic furrow positioning is essential to ensure proper DNA segregation. Here, we present a novel mechanism, which corrects DNA segregation defects due to cytokinetic furrow mispositioning during the first division of C. elegans embryos. Correction of DNA segregation defects due to an abnormally anterior cytokinetic furrow relies on the concomitant and opposite displacements of the furrow and of the anterior nucleus toward the posterior and anterior poles of the embryo, respectively. It also coincides with cortical blebbing and an anteriorly directed cytoplasmic flow. Although microtubules contribute to nuclear displacement, relaxation of an excessive tension at the anterior cortex plays a central role in the correction process and simultaneously regulates cytoplasmic flow as well as nuclear and furrow displacements. This work thus reveals the existence of a so-far uncharacterized correction mechanism, which is critical to correct DNA segregation defects due to cytokinetic furrow mispositioning.