Fig. 4.
FOXO and JNK signaling mediate the Sir2-induced apoptotic phenotype. (A) Overexpression of p53 has an additive effect on the severity of the sir2 eye phenotype. The sir2 phenotype cannot be rescued by overexpression of p53 dominant negatives. (B) Sir2 overexpression in a foxo null background shows significant recovery of pigmentation and eye structure. (C) Transcription level of puckered (puc), a JNK target gene, is significantly increased when measured by real-time RT-PCR. Values represent mean ± SEM, P = 0.0001, n = 4. (D) Coexpression of sir2 and the Drosophila JNK dominant negative (bskDN) ameliorates the eye phenotype. Additionally, coexpression of puc, a JNK activity inhibitor, shows a similar rescue, suggesting that JNK activity is required for sir2-mediated eye phenotype. (E) Transcription levels of proapoptotic genes increase significantly in heads of flies overexpressing sir2. Values represent mean ± SEM. reaper: P = 1.2 × 10−10, n = 10; grim: P = 0.009, n = 4; hid: P = 0.02, n = 3, rpd3: P = 0.276, n = 3, CG5085: P = 0.291, n = 3. (F) Expression of sir2 in the Df(3L)H99 deficiency background shows a partial rescue of the eye phenotype. (G) Pupal retina of a sir2 deletion fly is larger than that of a control when exposed to 5mJ/cm2 of UV irradiation. (H) The ratio of size between normal and UV-exposed retinas is calculated. Retinas of sir22A-7-11 flies are on average 50% larger than those of control w1118. Values represent mean ratio of the affected to unaffected eye ± SEM. P = 0.0005, n = 10 for each genotype.