Extended Data Fig. 4: ATM promotes GABARAP-WSTF binding and WSTF degradation.

a and b, Proliferating (Untr.) or senescent IMR90 cell lysates were subjected to GST-tagged GABARAP pulldown (a) with or without lambda protein phosphatase treatment of the cell lysates (b), then followed by immunoblotting with indicated antibodies. c, IMR90 cells expressing HA-GFP or HA-GABARAP were treated with IR to induce senescence with or without ATM inhibitor KU-55933 (ATMi), then subjected to HA immunoprecipitation followed by immunoblotting with indicated antibodies. d, Untreated or senescent IMR90 cells treated with or without ATMi were subjected to GST-tagged GABARAP pulldown, then evaluated by immunoblotting with the indicated antibodies. e, mCherry-GFP-tagged WSTF stably expressing ARPE19 cells and IMR90 cells were either left untreated, or treated with etoposide to induce senescence. ATMi was added after 5 days of etoposide treatment and the cells were analysed after 10 days of etoposide treatment. Cells were imaged using a confocal microscopy. Representative images and scale bars are shown. f, Bar graphs showing the quantification of the percentage of cells with cytoplasmic GFP or mCherry. Data presented are mean values from four randomly selected fields, with over 200 cells analysed. Error bars: s.d. ****P < 0.0001; one-way ANOVA coupled with Dunnett’s post hoc test. g, Untreated or senescent IMR90 cells stably expressing non-targeting control (sh-NTC) or sh-ATM were subjected to GST-tagged GABARAP pulldown followed by immunoblotting with indicated antibodies. The western blot experiments shown in a-d and g were repeated independently at least three times with similar results.