Figure 1.

HFD contributes to phospholipid accumulation in the dysfunctional lysosomes of PTCs. (A) PAS-stained kidney cortical regions of nonobese or obese mice that were either fed or subjected to 24 hours of starvation (n=6–9 in each group). Magnified images are shown in the insets (original magnification, ×1000). (B) Kidney sections of nonobese and obese GFP-MAP1LC3 transgenic mice (n=6–9 in each group) were immunostained for LAMP1, a marker of lysosome, or LRP2/MEGALIN, a marker of proximal tubules (red), and counterstained with DAPI (blue). (C) PTCs isolated from wild-type mice stably expressing GFP-MAP1LC3 were stained with LysoTracker Red, and counterstained with DAPI (blue) after treatment with either 0.25% BSA or 0.25 mM PA for 12 hours (n=5). (D) PTCs were stained with the pH indicator LysoSensor Yellow/Blue after treatment with either 0.25% BSA or 0.25 mM PA for 12 hours (n=5). The blue/yellow ratio is presented (right). (E) Cellular ATP levels after treatment with either 0.25% BSA or 0.25 mM PA for 12 hours. (n=5). (F–M) Electron micrographs of PTCs treated with 0.25% BSA (F–I) or with 0.25 mM PA (J–M) (n=2). (M' and I') Outer mitochondrial membranes are traced (solid lines). Bars: 50 μm (A), 10 μm (B, C, and D), 5 μm (F and J), and 500 nm (G–I and K–M). Data are provided as mean±SEM. Statistically significant differences (*P<0.05) are indicated. All images are representative of multiple experiments. M, mitochondria.