Redox State and ATP/ADP Ratio before and after mt-KR Activation in N2a Cells
(A) “Dose effect” of mt-KR photoactivation on the mitochondrial redox state. To activate mt-KR-induced ROS production, cells were scanned between 1 and 20 times (1×–20×). The fluorescence ratio of the matrix-roGFP protein (405 nm/488 nm = oxidized/reduced state) was measured every 30 s for 5 min after photostimulation, and again after 30 min. Values represent the mean ± SEM of n = 10–15 cells/group from 3 independent experiments.
(B) Mitochondrial redox state before and 30 s and 30 min after mt-KR activation in the different photostimulated groups. Values represent the mean ± SEM of 10–15 cells. One-way ANOVA (repeated measurements) and Dunnett's multiple comparisons test versus baseline (before mt-KR), *p < 0.05; ***p < 0.001.
(C–E) Fluorescence ratio (405 nm/488 nm) of the matrix-roGFP protein before (C), 30 s after (D), and 30 min after (E) mt-KR activation. An increase in the signal indicates an increase in oxidation in the mitochondria. For each representative image, a zoomed-in image is shown (400%).
(F–H) Fluorescence ratio (405 nm/488 nm) of the cyto-roGFP protein before (F), 30 s after (G), and 30 min after (H) mt-KR activation. An increase of the signal indicates an increase in oxidation in the cytosol. For each representative image, a zoomed-in image is shown (400%).
(I–K) Fluorescence ratio (488 nm/405 nm) of the Perceval protein (ATP/ADP ratio) before (I), 30 s after (J), and 30 min after (K) mt-KR activation. A decrease in the signal indicates a decrease in the ATP/ADP ratio. For each representative image, a zoomed-in image is shown (400%).
(L) Cytosolic redox state in cyto-roGFP-transfected cells after acute mt-KR activation (scanned 20×). Values represent the mean ± SEM of 19 cells from 3 independent experiments.
(M) ATP/ADP ratio in Perceval-transfected cells after acute mt-KR activation (scanned 20×) and analysis of the signal before, 30 s after, and 30 min after mt-KR activation. Values represent the mean ± SEM of 18 cells from 3 independent experiments. One-way ANOVA (repeated measurements) and Dunnett's multiple comparisons test versus baseline (before mt-KR), *p < 0.05; **p < 0.01; ***p < 0.001.
mt-DS, mito-DsRed.