FIGURE 1.

LysoTracker decorates the limiting membrane and intraluminar vesicles in swollen lysosomes induced by PIKfyve inhibition. A, levels of PtdIns, PtdIns(3)P, and PtdIns(3,5)P₂ from [³H]myo-inositol-labeled cells after treatment with vector (DMSO) or 20 nm apilimod for 1 h. Levels are relative to PtdIns and normalized to vector-treated cells. B and C, RAW cells were treated with vector alone (B, DMSO) or with 20 nm apilimod (C) for 1 h followed by labeling with LysoTracker for 10 min. Live cells were then imaged at 5 frames/s for 10 s by spinning disc confocal microscopy. Each illustrated frame is 1 s apart, showing a 5-s sequence. Arrowheads point to a LysoTracker-positive lysosome (B) or to a moving ILV in apilimod-treated cells (C). See also supplemental Movie S1 and Movie S2. Scale bar = 5 μm.