Figure 9: Transcriptional control of bcat-1-mediated regulation of lifespan.

(a) Fluorescent microscopy of nematodes transgenically expressing bcat-1 fused to GFP under the control of the endogenous bcat-1 promoter, at different ages (scale bar, 100 μm). (b) Shows the effect of bcat-1 overexpression on lifespan (P<0.001, log-rank test, n=3). (c) Depicts fertility as reflected by the number of eggs (***P<0.001, Students’s t-test, n=10). (d) Depicts transcript levels of bcat-1 in the presence of control RNAi (white), RNAi against hlh-15 (blue) and bcat-1 (red) in wild-type nematodes (***P<0.001, ****P<0.0001 versus control, one-way ANOVA, n=4). (e) Shows transcript levels of bcat-1 (black) and hlh-15 (grey) during physiological ageing in wild-type worms (*P<0.05, one-way ANOVA, Pearson correlation Fisher Z, P=0.053, n=3). (f) Depicts the effects of control RNAi (black), control RNAi combined with bcat-1 RNAi (red; P<0.0001 versus control, log-rank test, n=3), control RNAi combined with hlh-15 RNAi (blue; P<0.0001 versus control, log-rank test, n=3) and bcat-1 RNAi combined with hlh-15 RNAi (purple, epistasis; P<0.0001 versus control, P=0.08 versus control/bcat-1 RNAi, log-rank test, n=3) on C. elegans lifespan. (g) Summarizes the effects of hlh-15-controlled bcat-1 expression, or BCAA supplementation, on neuronal let-363/daf-7 signaling looping back to the periphery to control lifespan. For P-values and number of repetitions see Supplementary Table 4. Error bars represent the means±s.d.