Fig. 1
JNK persistent activity after irradiation or a short pulse of p53 and JNK in apoptosis-deficient cells. a Simplified representation of the apoptotic pathway in Drosophila. JNK/p53 are activated after irradiation and induce the activation of the pro-apoptotic genes that block DIAP1, inducing the activation of the apical caspase Dronc and effector caspases Dcp1 and Drice. Besides, Dronc reinforces JNK activity generating an amplification loop that augments the apoptotic response26. As a side event, JNK activates the Dpp, Wg and JAK/STAT pathways. b-g Wing discs showing the effects of X-rays at different time points. JNK activity is monitored by the expression of a LacZ insert at the JNK target puckered (puc, red). The blue background reflects TOPRO staining. b, c puc expression in non-irradiated dronc+ control (n = 10) and null dronc− mutant (n = 17) discs. Note that the label is restricted in both cases to a small region that corresponds to the most proximal zone of the disc. d, e Twenty-four hours after irradiation, both dronc+ (n = 22) and dronc− (n = 18) discs show high expression levels of puc, especially in the region corresponding to the wing pouch. f, g puc expression 96 h after irradiation in dronc+ (n = 28) and dronc− (n = 31) discs. Whereas puc levels have returned to normal in dronc+ (f), they remain high in many zones of the dronc− discs (g). Wing discs of genotype: h UAS-p53/UAS-GFPtubGal80ts;hh-Gal4dronci29/+ (n = 10), i UAS-p53/UAS-GFPtubGal80ts;hh-Gal4dronci29/dronci29 (n = 14), j UAS-hepCA/UAS-GFPtubGal80ts;hhGal4dronci29/+ (n = 10) and k UAS-hepCA/UAS-GFPtubGal80ts;hh-Gal4dronci29/dronci24 (n = 11). Discs are stained with Cubitus interruptus, Ci (green) to mark the anterior compartment and Mmp1 (red) to monitor JNK activity. The short pulse of p53 (h, i) or of hepCA (j, k), at the posterior compartment is administered by temperature shift, detailed in Methods section; 96 h after the change to 17 °C, no activity of JNK can be detected by Mmp1 staining (red) in the posterior compartment (lack of green) in p53 dronc+ (h) and hepCA dronc+ discs (j). In contrast, there is JNK activity (red) at the posterior compartment (lack of green) of p53 dronc− (i) and in hepCA dronc− discs (k). Scale bars are 100 μm
