Effect And Mechanism Of β-guanidinopropionic Acid On The Lifespan Of Drosophila

Part I Effects of beta-Guanidinopropionic acid on lifespan of DrosophilaObjectives:β-guanadinopropionic acid (β-GPA), a creatine analog has been demonstrated to lead to the chronic activation of AMPK and increases mitochondrial enzyme activities and biogenesis. Numerous studies have shown a role for AMPK and mitochondrial in aging. However, little is known about the role of β-GPA in lifespan extension. In this study, we hypothesized that feeding β-GPA to adult Drosophila produces the lifespan extension.Methods:The flies were fed in a normal chow diet containing different concentrations (300mM,900mM,2700mM) of p-GPA to determine whether β-GPA can extend lifespan in Drosophila. We examined β-GPA-treated flies for survival under starvation or treatment with the oxidative stress inducer H2O2. The assay for SOD and MDA activity was performed according to the protocols of the SOD and MDA kit.Results:(1)900mM and2700mM β-GPA produces a significant effect on lifespan extension both in male and female Drosophila (900mM:females:60d (control) vs.65d (β-GPA); males:55d (control) vs.59d (β-GPA);2700mM:females:60d (control) vs.68d (β-GPA); males:55d (control) vs.60d (β-GPA)).(2)900mM β-GPA significantly increased the median lifespan under starvation both in male and female Drosophila (females:5d (control) vs.7d (β-GPA); males:5d (control) vs.7d (P-GPA)), and increases the resistance of Drosophila to various stresses.(3)900mM β-GPA increased the median lifespan under oxidation (females:1d (control) vs.2d (β-GPA); males:1d (control) vs.2d (p-GPA)), and caused a decrease in MDA content and an increase in the activity of SOD both in females and males when compared to the control.Conclusion:Thus, these results demonstrate that P-GPA can extend lifespan, increase starvation resistance and the ability of anti-oxidation in Drosophila. Part Ⅱ Mechanisms of lifespan extension in Drosophila by beta-guanidinopropionic acidObjective:Chronic activation of AMPK can extend lifespan. Previous studies have demonstrated that β-GPA can chronic activate AMP-activated protein kinase (AMPK), which controls autophagy through the mammalian target of rapamycin (mTOR) and Unc-51like kinase1(ULK1/Atgl) signaling. Recent studies have revealed that autophagy has been shown to play an important role in lifespan extension, but whether β-GPA extended lifespan via AMPK-dependent autophagy was unknown. In this study, we investigated the mechanisms of lifespan extension in Drosophila by β-GPA.Methods:Western blotting was used to investigate protein expressions in this section. RNA interference was employed to examine effects of lifespan in Drosophila by β-GPA. Results:(1) AMPK was ubiquitously downregulated in Drosophila upon900mM and2700mM β-GPA treatment (control:100±13.54,900mM:143.36±12.2,2700mM:147.13±8.54in heads; control:100±15.49,900mM:155.14±17.53,2700mM:155.78±14.59in thoraces; control:100±13.35,900mM:152.91±15.8,2700mM:152.4±16.14in abdomens).(2) We found that Atg8protein, the homologue of microtubule-associated protein1A/1B-light chain3(LC3), a biomarker of autophagy in Drosophila, was significantly upregulated and P62was significantly downregulated by900mM β-GPA, on the other hand, when the expression of Atg5protein, an essential protein for autophagy, was reduced by RNA interference (RNAi), the effect of P-GPA on lifespan extension was abolished (females:62d (P-GPA) vs.51d (Atg5-RNAi+β-GPA); males:59d (β-GPA) vs.51d (Atg5-RNAi+β-GPA)).(3) Inhibition of AMPK by AMPK-RNAi, significantly attenuated the expression of autophagy-related proteins and lifespan extension in Drosophila (females:68d (β-GPA) vs.54d (compound C+β-GPA); males:60d (β-GPA) vs.50d (compound C+β-GPA)).(4) Atgl may be responsible for lifespan extension and autophagy induced by β-GPA.(5) We found that the activation of AMPK induced by P-GPA inhibited mTORC1activity, implicating that mTORC1may not prevent the activation of ULK1/Atg1by AMPK.Conclusion:In this study, we demonstrated that dietary application of P-GPA can extend the lifespan of Drosophila and this effect was mediated by AMPK-Atgl dependent autophagy.