LAUSR

We examined the mechanism of cell membrane repair in Dictyostelium cells by using a novel laser-based cell poration method. The dynamics of wound pores opening and closing were characterized by live imaging of fluorescent cell membrane proteins, influx of fluorescent dye, and Ca2+ imaging. The wound closed within 2–4 sec, depending on the wound size. Cells could tolerate a wound size of less than 2.0 µm. In the absence of Ca2+ in the external medium, the wound pore did not close and cells ruptured. The release of Ca2+ from intracellular stores also contributed to the elevation of cytoplasmic Ca2+ but not to wound repair. Annexin C1 immediately accumulated at the wound site depending on the external Ca2+ concentration, and annexin C1 knockout cells had a defect in wound repair, but it was not essential. Dictyostelium cells were able to respond to multiple repeated wounds with the same time courses, in contrast to previous reports showing that the first wound accelerates the second wound repair in fibroblasts.