Effects of wounds in the cell membrane on cell division.

Cells are consistently subjected to wounding by physical or chemical damages from the external environment. We previously showed that a local wound of the cell membrane modulates the polarity of cell migration and the wounded cells escape from the wound site in Dictyostelium. Here, we examined effects of wounds on dividing cells. When the cell membrane at the cleavage furrow during cytokinesis was locally wounded using laserporation, furrow constriction was significantly accelerated. Neither myosin II nor cortexillins contributed to the acceleration, because the acceleration was not hindered in mutant cells deficient in these proteins. When the cell membrane outside the furrow was wounded, the furrow constriction was not accelerated. Instead, the wounded-daughter half became smaller and the unwounded half became larger, resulting in an asymmetrical cell division. These phenomena occurred independently of wound repair. When cells in anaphase were wounded at the presumptive polar region, about 30% of the wounded cells changed the orientation of the division axis. From these observations, we concluded that dividing cells also escape from the wound site. The wound experiments on dividing cells also provide new insights into the mechanism of cytokinesis and cell polarity establishment.