Fig. 5

dAtg1 is transcriptionally induced for AiP in a JNK-dependent manner. Late third instar wing discs, anterior is to the left. White dotted lines indicate the anterior/posterior compartment boundaries. hh-Gal4 is used to drive expression of various transgenes in the posterior compartment of wing discs. (a–d’) Wing discs are labeled with dATG1 (red in a, b, c, d and grey in a’, b’, c’, d’). GFP marks the posterior disc compartment where hh-Gal4 is expressed (green in a, b, c, d). Compared to hh > p35 controls (a, a’), co-expression of hid and p35 by hh > Gal4 induces overgrowth of the posterior wing compartment as indicated by enlarged tissue size and folded disc morphology (b, b’). dATG1 protein is strongly increased in the overgrown posterior tissue (compare b’ to a’). Knockdown of JNK (bsk ^RNAi) has no effect on dATG1 expression in the control hh > p35 discs (c, c’), but it suppresses overgrowth as well as accumulation of dATG1 in hh > hid-p35 discs (compare d, d’ to b, b’). (e–l) Wing discs labeled with dAtg1 in situ antisense probes (red in e, f and grey in g–l). (e, f) Compared to the control (e), dAtg1 transcription, as indicated by the fluorescent in situ signals of dAtg1, is increased in hh > hid-p35 discs (f). (g–l) hh-Gal4 tub-Gal80 ^ts (hh ^ts) was used to control temporal expression of GAL4 alone as the control (g), hid (h, i, k), hid and bsk ^RNAi (j), or a constitutively activated form of JNK kinase, hep ^CA (l). A weak increase of dAtg1 transcript was observed in the posterior wing tissues after a 15 h expression of hid (h, arrows). dAtg1 transcript is strongly increased after hid expression for 68 h (i, arrows). This increase of dAtg1 transcripts is inhibited by knockdown of JNK (bsk ^RNAi) with only a low level of dAtg1 induction left in hh ^ts  > hid,bsk ^RNAi discs (j, arrow, compared to i). Although expression of hid at 29 °C for 6 h followed by recovery at 18 °C for 6 h (TS6hR6h) does not trigger accumulation of dAtg1 (k), expression of hep ^CA (to activate JNK) under the same condition is sufficient to induce expression of dAtg1 (l, arrows)