Contractile‐ring assembly in fission yeast cytokinesis: Recent advances and new perspectives

Abstract

The fission yeast Schizosaccharomyces pombe is an excellent model organism to study cytokinesis. Here, we review recent advances on contractile-ring assembly in fission yeast. First, we summarize the assembly of cytokinesis nodes, the precursors of a normal contractile ring. IQGAP Rng2 and myosin essential light chain Cdc4 are recruited by the anillin-like protein Mid1, followed by the addition of other cytokinesis node proteins. Mid1 localization on the plasma membrane is stabilized by interphase node proteins. Second, we discuss proteins and processes that contribute to the search, capture, pull, and release mechanism of contractile-ring assembly. Actin filaments nucleated by formin Cdc12, the motor activity of myosin-II, the stiffness of the actin network, and severing of actin filaments by cofilin all play essential roles in contractile-ring assembly. Finally, we discuss the Mid1-independent pathway for ring assembly, and the possible mechanisms underlying the ring maturation and constriction. Collectively, we provide an overview of the current understanding of contractile-ring assembly and uncover future directions in studying cytokinesis in fission yeast.

Hydroxyurea Induces Cytokinesis Arrest in Cells Expressing a Mutated Sterol-14α-Demethylase in the Ergosterol Biosynthesis Pathway

“…However, it remains unclear whether this cell-killing mechanism is conserved in all eukaryotic organisms and how this mechanism is related to the cytokinesis arrest discovered in this study. Understanding the HU-induced cytokinesis arrest may shed new light on the cytotoxicity of HU and derive new therapeutic potentials because cytokinesis has been widely exploited as an antiproliferative strategy for the development of cancer chemotherapeutics (Bathe and Chang 2010;Lee et al 2012).…”

“…Failure in cytokinesis results in aneuploidy and contributes to tumorigenesis (Bathe and Chang 2010;Lee et al 2012). Since ergosterol is enriched in the septum, it is possible that its deficiency directly affects the cell separation process.…”

“…Cytokinesis is the final stage of the cell division cycle and requires the proper placement, assembly, and contraction of the contractile ring, which dictates septum formation and cell separation (Bathe and Chang 2010;Johnson et al 2012;Lee et al 2012). The HU-induced cytokinesis observed in erg11-1 cells is likely a new cell-killing mechanism of this clinically important drug.…”

Novel roles for actin in mitochondrial fission

“…Cytokinesis is another myosin-dependent event, resulting in membrane constriction and division. The best-studied model for cytokinesis is fission yeast, for which a clear set of molecular factors and sequence of events has been defined (Lee et al, 2012;Pollard, 2010). Myosin II accumulates at the prospective cleavage furrow in precursor structures, called 'nodes'.…”

“…This model uses aspects of the node-based model that has been described for fission yeast cytokinesis (Lee et al, 2012;Pollard, 2010), in which a loose cluster of nodes containing formin and myosin II develops at the cleavage site. In the case of mitochondrial fission, these nodes would assemble on the ER.…”