Fig. 4: Swip-1 is recruited to lamellipodial protrusions during epithelial wound closure in vivo.

a Schematic of the in vivo model to study calcium-dependent wound healing in early Drosophila pupal stages. b, c Single-cell ablation in the abdominal epidermis of a wild-type 18 h APF old pupa ubiquitously expressing a Lifeact-eGFP transgene under the control of the da-Gal4 driver. Images were taken every 30 s for 30 min, ablation starts at t = 0 min. b Overview of the imaged area of the monolayered epithelium, an asterisk indicates ablated cell. Scale bar 25 µm. c Magnification of the ablated cell of b at the indicated times. Arrows show forming lamellipodial protrusions at the wound margin. Scale bar 25 µm. d Single-cell ablation in the abdominal epithelium of a 18 h APF old pupa ubiquitously expressing Swip-1-eGFP transgene; yellow asterisk indicates the position of the ablated cell. White asterisks mark specialized epidermal cells, so-called tendon cells providing attachment sides to the muscles. These tendon cells lack Swip-1-eGFP expression driven by the da-Gal4 driver. Yellow arrows mark lamellipodial protrusions at the wound margin, whereas white arrows mark induced lamellipodia of cells several rows back from the wound site exhibited a delayed response. Scale bar 25 µm. e Single-cell ablation in the abdominal epidermis of a 18 h APF old pupa ubiquitously expressing the calcium indicator RCaMP. Changes of intracellular calcium are visible as increasing fluorescence intensity. The calcium wave is propagated in a circular fashion with a velocity of 2.2 ± 0.7 µm/s. Scale bar 25 µm. c–e Images shown are representative of a nine and b, c at least three independent experiments. f Schematic of the calcium wave-inducing membrane protrusions after wounding.