Fig. 3. ClpP and LONP1 protect mitochondria functions required for cell survival under stress conditions.

A–F LNCaP and DU145 cells were transfected with control non-targeting siRNA (siCtrl) or LONP1 (siLONP1) and/or ClpP-directed siRNA (siClpP) for 72 h. A Total cell lysates were analyzed by western blotting for phosphorylation of AMPK (Thr172) and ULK1 (Ser555), p62 and LC3-I/II. p, phosphorylated. B ATP production. C Mitochondrial ROS levels. Data representative of three independent experiments are shown. Mean ± SD (n = 3). *p < 0.05, **p < 0.01, ***p < 0.001. D Representative images of MitoSOX Red (for mitochondrial superoxide) and MitoTracker Green (for mitochondrial content) fluorescence. Scale bar = 5 µm. Quantitative analysis of fluorescence intensity is shown in the right panel. Integrated pixel intensities from MitoSOX Red signals were normalized by the area occupied by MitoTracker Green. Whole images and 40 cells per group were used for calculations. Data are shown as mean ± SD of individual cells. ***p < 0.001. E, F DU145 cells were transfected with siCtrl or siLONP1 and/or siClpP for 48 h. Cells were incubated in (E) H₂O₂ (100 μM) or (F) low glucose (0.5 mM) for 24 h. Cell proliferation was measured by direct cell counting. Mean ± SD (n = 3). **p < 0.001, ***p < 0.0001, n.s., not significant.