Multinucleate cells can be produced in Dictyostelium by electric-pulse induced fusion. In these cells unilateral cleavage furrows are formed at spaces between areas that are controlled by aster microtubules. A peculiarity of unilateral cleavage furrows is their propensity to join laterally with other furrows into rings to form constrictions. This means, cytokinesis is biphasic in multinucleate cells, the final abscission of daughter cells being independent of the initial direction of furrow progression. Myosin-II and the actin-filament cross-linking protein cortexillin accumulate in the unilateral furrows, as they do in the normal cleavage furrows of mononucleate cells. Myosin-II is not essential for cytokinesis, but stabilizes and confines the position of the cleavage furrows.

Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate, to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), while deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy, in root cells of the fra2 Arabidopsis thaliana mutant. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls appeared also faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild-type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild-type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.

Cytokinesis, as the last stage of the cell division cycle, is a tightly controlled process amongst all eukaryotes, and defective division can lead to severe cellular consequences, and is implicated in serious human diseases and conditions such as cancer. Both mammalian cells and the fission yeast Schizosaccharomyces pombe use binary fission to divide into two equal sized daughter cells. In S. pombe such cytokinetic division is driven by the assembly of an actin-myosin contractile ring (ACR) at the cell equator between the two cell tips. The ACR is composed of a complex network of membrane scaffold proteins, actin filaments, myosin motors, and other cytokinesis regulators. Contraction of the ACR leads to the formation of a cleavage furrow which is severed leading to the final cell separation during the last stage of cytokinesis, abscission. This review describes recent findings defining the three phases to establish cytokinesis in S. pombe: ACR assembly, ACR constriction, and its coordination with septation. Collectively, we provide an overview of current understanding of the mechanisms regulating the ACR-mediated cytokinesis in S. pombe.

Cytokinesis, as the last stage of the cell division cycle, is a tightly controlled process amongst all eukaryotes, and defective division can lead to severe cellular consequences, and is implicated in serious human diseases and conditions such as cancer. Both mammalian cells and the fission yeast Schizosaccharomyces pombe use binary fission to divide into two equal sized daughter cells. Similar to mammalian cells, in S. pombe such cytokinetic division is driven by the assembly of an actin-myosin contractile ring (ACR) at the cell equator between the two cell tips. The ACR is composed of a complex network of membrane scaffold proteins, actin filaments, myosin motors, and other cytokinesis regulators. Contraction of the ACR leads to the formation of a cleavage furrow which is severed by the endosomal sorting complex required for transport (ESCRT) proteins leading to the final cell separation during the last stage of cytokinesis, abscission. This review describes recent findings defining the three phases to establish cytokinesis in S. pombe: ACR assembly, ACR constriction, and its coordination with septation. Collectively, we provide an overview of current understanding of the mechanisms regulating the ACR-mediated cytokinesis in S. pombe with a potential role of ESCRT proteins in this process.