Figure 8. High dRagA activity sensitizes Drosophila to starvation.
(a, b) dRagA activation increases sensitivity to starvation. Expression of dRagA Q61L using the fat body-specific Cg-GAL4 driver significantly decreases survival of adult female flies under starvation (a) conditions but not fed (b) conditions, relative to controls (Cg-GAL4 alone). Asterisks indicate time points with significant difference compared to controls (*P<0.05; Students two-tailed t-test; n = 150 flies/genotype/treatment).
(c) A proposed model of Rag GTPase in regulation of TORC1 activity. Rag GTPases act independently of and in parallel to TSC-Rheb to activate TOR signaling, possibly by transducing a nutrient-dependent signal. The mechanism of TOR regulation by Rag GTPases is indirect, and likely involves additional unidentified factors.