Figure 8.

Combined RNAi of mrps-5;eat-3 promotes autophagic activity. (A) The number of AP and AL was measured in the pharynx of day 2 adult worms expressing tandem autophagy reporter mCherry::GFP::LGG-1 and treated with RNAi against mrps-5 alone or against mrps-5 and eat-3 simultaneously. Scale bar, 20 µm. (B) Quantification of AP and AL in A. mCherry::GFP::LGG-1- and mCherry::LGG-1–positive punctae were counted in 30 worms per genotype at day 2 of adulthood. Data were derived from two independent experiments. Mean ± SEM, *, P < 0.05; **, P < 0.01; ****, P < 0.0001; ns, not significant by one-way ANOVA with Tukey’s multiple comparisons test. (C) The number of AP and AL was measured in the seam cell of day 2 adult mCherry::GFP::LGG-1 reporter worms fed on bacteria expressing ev, mrps-5, or mrps-5;eat-3 in combination. Scale bar, 20 µm. (D) Quantification of AP and AL in C. mCherry::GFP::LGG-1- and mCherry::LGG-1–positive punctae were counted in 24–26 worms per genotype at day 2 of adulthood. Data were pooled from two independent experiments. Mean ± SEM; ***, P < 0.001; ****, P < 0.0001; ns, not significant by one-way ANOVA with Tukey’s multiple comparisons test. (E) Model for mitochondrial dynamics and mitochondrial translation-mediated longevity signaling pathway. (a) Upon absence of external stress in mitochondrial translation and dynamics, HLH-30 resides in the cytosol and animals live a normal lifespan. (b and c) Inhibition of either fusion (b) or fission (c) in conjunction with impaired mitochondrial translation synergistically promotes HLH-30 trafficking to the nucleus, whereupon it prolongs lifespan by up-regulating lysosome biogenesis and autophagy process. (d) Simultaneous suppression of fission and fusion abrogates the effect of mrps-5 RNAi on the HLH-30 nuclear localization, which in turn compromises its downstream longevity benefits.