Mechanisms controlling division-plane positioning.

A critical and irreversible step in the cell division cycle is cytokinesis which physically separates the two daughter cells. This event is consequently subject to tight spatial and temporal regulation. This review focuses on the spatial regulatory mechanisms controlling the position of the division plane. Studies performed in prokaryotic and eukaryotic systems have revealed that various signal-emitting spatial cues - mitotic spindle, nucleus, nucleoid or cell tips - can favour or inhibit the assembly of the cytokinetic apparatus in their vicinity. Most often, several mechanisms operate in parallel to integrate spatial information and promote faithful genome segregation as well as proper cytoplasmic division. We primarily describe the spatial regulatory mechanisms operating in the fission yeast model system, where a detailed molecular understanding of cytokinesis has been achieved. In this system, spatial regulations target a major factor controlling the position of the division plane, the anillin-like protein Mid1. These mechanisms are then compared to spatial regulatory mechanisms prevailing in animal cells and rod-shaped bacteria.