Understanding the regulation of cytokinesis in fission yeast

Abstract

Cytokinesis is coordinated temporally and spatially with nuclear division and cellular geometry to ensure genomic stability. The fission yeast Schizosaccharomyces pombe, like in animal cells, utilizes an actomyosin ring for cytokinesis. A GTPase-driven signaling cascade, Septation Initiation Network (SIN), is activated to promote septum assembly and ring constriction. How SIN signaling is inactivated following cytokinesis remains largely unclear. I showed that a TPR-containing subunit of APC/C, Nuc2p inactivates SIN after completion of cytokinesis to allow further cell division. Furthermore, through the characterization of a novel gene pal1, I showed that the cell geometry is important in coordinating the division plane and mitotic spindle. Cells that are defective in Pal1p function have abnormal cell morphology and repolarize in a Tea1p-dependent manner to establish a cylindrical axis prior to cell division. Failure of repolarization leads to mis-coordination of cytokinesis and mitosis, leading to genomic instability in spherical cell.