Abstract

Cytokinesis is the final stage of the cell cycle, and ensures completion of both genome segregation and organelle distribution to the daughter cells. Cytokinesis requires the cell to solve a spatial problem (to divide in the correct place, orthogonally to the plane of chromosome segregation) and a temporal problem (to coordinate cytokinesis with mitosis). Defects in the spatiotemporal control of cytokinesis may cause cell death, or increase the risk of tumor formation [Fujiwara et al., 2005 (Fujiwara T, Bandi M, Nitta M, Ivanova EV, Bronson RT, Pellman D. 2005. Cytokinesis failure generating tetraploids promotes tumorigenesis in p53-null cells. Nature 437:1043–1047); reviewed by Ganem et al., 2007 (Ganem NJ, Storchova Z, Pellman D. 2007. Tetraploidy, aneuploidy and cancer. Curr Opin Genet Dev 17:157–162.)]. Asymmetric cytokinesis, which permits the generation of two daughter cells that differ in their shape, size and properties, is important both during development, and for cellular homeostasis in multicellular organisms [reviewed by Li, 2007 (Li R. 2007. Cytokinesis in development and disease: variations on a common theme. Cell Mol Life Sci 64:3044–3058)]. The principal focus of this review will be the mechanisms of cytokinesis in the mitotic cycle of the yeast Schizosaccharomyces pombe. This simple model has contributed significantly to our understanding of how the cell cycle is regulated, and serves as an excellent model for studying aspects of cytokinesis. Here we will discuss the state of our knowledge of how the contractile ring is assembled and disassembled, how it contracts, and what we know of the regulatory mechanisms that control these events and assure their coordination with chromosome segregation. © 2011 Wiley-Liss, Inc.

Highlights

  • We will briefly introduce the S. pombe model, giving references to reviews addressing aspects of fission yeast biology that are beyond the scope of this overview

  • Though the behavior of many individual contractile ring (CR) proteins had been analyzed previously, this study examined many CR markers in parallel, under similar filming and growth conditions, enabling the relative timing of their appearance at the CR to be investigated

  • These filaments are often composed of many small bundles in series, each of which has an average length of 0.6 lm in S. pombe cells

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Summary

Introduction

We will briefly introduce the S. pombe model, giving references to reviews addressing aspects of fission yeast biology that are beyond the scope of this overview. The second is nuclear export of mid1p at the G2/M transition, which targets mid1p to the cortex proximal to the nucleus [Sohrmann et al, 1996; Paoletti and Chang, 2000; Daga and Chang, 2005], which is likely to be mediated by plo1p [Bahler et al, 1998]; Plo1p directly binds to mid1p and seems to play an important role in formation of the medial mid1p ring; the protein kinase pdk1p contributes to this process [Bimbo et al, 2005] Consistent with this, both kinases localize to SPB and the medial ring in mitosis [Bahler et al, 1998; Bimbo et al, 2005]. Redundant mechanisms including a positive spatial cue from the centrally positioned nucleus and inhibitory signals at the cell tips contribute to medial positioning of the division plane to produce similar-sized daughter cells

A Time Course of CR-Assembly
A Checkpoint in CR Assembly
Conclusions

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