Fig. 2

Lysosomal exocytosis is increased in cartilage of multiple models of lysosomal storage (A) Schematic of heat shock inducible Lamp1 protein and experimental procedure to assay Lamp1 abundance and subcellular localization. (B) Western blots probed for Lamp1 transgene in heat shocked animals suggest Lamp1 abundance is altered when neu1, gnptab, or galns expression is reduced, but not in those injected with a control morpholino (rc, random control). (C–F) Graphs quantitating the protein abundance of Lamp1-mCherry transgene in larvae harvested at various times post-heat shock. The level present at each time point is normalized to the amount of Lamp1 present 0.5 h post heat shock. n = 3 biological replicates of samples containing 10 larvae per genotype per time point. Error = SEM, Student’s t test ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001. (G) Live confocal images of Lamp1-mCherry (red) in fli1a:EGFP (green) positive chondrocytes show increased cell surface abundance indicating increased exocytosis in neu1, gnptab, and galns deficient animals. Images performed 8–10 h post-heat shock. Boxed regions, yellow asterisks. Scale bar: 10 μm. (H) The number of cells with high or moderate levels of Lamp1 (relative to total number of chondrocytes) was scored for each genotype. n = 10 larvae imaged and scored per genotype. See also Figure S2. Error = SEM, Student’s t test ∗∗∗p < 0.001 or Dunnet’s t test ∗∗p < 0.01, ∗∗∗p < 0.001.