Speck formation in the nucleus causes cell death. (A) Time-lapse of 3-dpf Tg(asc:asc-EGFP) larvae transiently expressing HSE:NLS-asc-mKate2 at 6 hphs, showing that nuclear speck assembly in keratinocytes (white dashed line) leads to cell death. (B–E) Cell undergoing cell death with nuclear speck and without depletion of ASC–GFP in the cytoplasm. Brightfield of respective time points show breakdown of nuclear envelope, allowing recruitment of cytoplasmic ASC–GFP (B′ and C′). Loss of plasma membrane integrity (F–I) before nuclear envelope breakdown, results in leakage of cytoplasmic ASC–GFP as shown in brightfield (H′ and I′). (J) Time-lapse imaging of transient ASC–mKate2 and GFP expression in Tg(βactin:NLS-tagBFP) larvae at 6 hphs. Yellow arrowheads signal speck formation events in two adjacent cells; first, within the cytoplasm, and second, within the nucleus. (J′) Intensity plot profile (white dashed line) before and after nuclear speck formation for all channels. (Middle and right) Green and red channels shown separately, highlighting ASC–mKate2 depletion only from nuclear pool. Full time-lapses are included in Video 6. Bars, 20 µm.