Fig. 3: FSP1 condensates are liquid droplets.
a, Representative time-lapse fluorescence images before and after treatment of wild-type Gpx4 Pfa1 cells stably overexpressing hFSP1–EGFP–Strep with 2.5 µM icFSP1. Representative results are shown from one of three independent experiments. Scale bars, 10 μm (2 µm for zoomed-in images). Arrowheads indicate fusion events of individual condensates. See also Supplementary Video 3. b, Reversibility of hFSP1 condensates. Representative time-lapse fluorescence images before and after treatment of wild-type Gpx4 Pfa1 cells stably overexpressing hFSP1–EGFP–Strep with 2.5 µM icFSP1. After treatment of cells with icFSP1 for 240 min, the medium was replaced with fresh medium without icFSP1 and recordings were restarted. Scale bars, 10 μm. Representative results from one of three independent experiments. See also Supplementary Video 4. c, FRAP assays after treatment of hFSP1–EGFP–Strep-overexpressing wlid-type Gpx4 Pfa1 cells with 2.5 µM icFSP1 for 120 min. Top, greyscale images corresponding to representative FRAP images immediately before and after photobleaching. Bottom, lookup table (LUT) images showing enlarged views of the areas in red rectangles in the top FRAP images. Scale bars, 10 μm. Representative results from one of three independent experiments. See also Supplementary Video 5. d, Quantified FRAP rate of each condensate. Data represent the mean ± s.d. of five condensates from c. Representative results from one of three independent experiments. e, FSP1 condensation in vitro. Representative fluorescence images of 1.5 µM EGFP–Strep and hFSP1–EGFP–Strep purified from transfected HEK29T cells were obtained immediately after mixing with or without 10% PEG. Scale bars, 10 μm. Representative results from one of three independent experiments are shown.
