Figure 2.

Simultaneous suppression of mitochondrial translation and fusion amplifies mitochondrial stress. (A) Double RNAi of mrps-5;eat-3 or mrps-5;fzo-1 synergistically activates the UPR^MT, visualized by hsp-6::GFP reporter strain at day 3 and day 7 of adulthood. Scale bar in ev-treated condition on day 3 represents 200 µm and is valid for all the images in A. (B) Quantification of GFP fluorescence intensity in A, expressed as fold change relative to wild type N2 fed on ev. Mean ± SD of n = 17 images. (C) Mitochondrial OCR after mrps-5 RNAi, mrps-5;eat-3 double RNAi, or mrps-5;fzo-1 double RNAi. The strongest reduction of basal OCR occurs in N2 worms treated with mrps-5;eat-3 double RNAi, while maximum OCR is reduced to an equal extent by three types of RNAi treatments. The OCR was measured in day 7 adult worms. Mean ± SD of n = 11–16 biological replicates. (D) Raw averaged traces of oxygen consumption from day 7 adult N2 worms treated with RNAi against mrps-5 alone or RNAi against mrps-5;eat-3 or mrps-5;fzo-1. Mean ± SEM (n = 16); FCCP, an uncoupler reagent, was added at the indicated time to achieve the maximum mitochondrial respiration, while sodium azide, a complex IV inhibitor, was added to fully block mitochondrial respiration, thereby measuring nonmitochondrial oxygen consumption. ***, P < 0.001; ****, P < 0.0001; ns, not significant by one-way ANOVA with Tukey’s multiple comparisons test.