The transcriptional effectors of the Hippo and dJNK pathways act synergistically to induce AM fragmentation. (A) org-1-RFP and phalloidin mark the VLM in pharate adult stage P15. (B) Forced expression of a membrane-tethered version of dominant-negative aPKC (org-1>>aPKC.CAAX.DN) with org-1-GAL4 has no effect on AM reprogramming. (C) Induction of a constitutive active form of aPKC (org-1>>aPKC.ΔN) with org-1-GAL4 disrupts VLM differentiation and AM transdifferentiation. (D) The lost VLM phenotype in an aPKC gain-of-function background can be partially rescued by coexpression of phosphorylation-resistant Yki^S168A (org-1>>aPKC.ΔN; yki.S168A). (E) org-1-GAL4–mediated induction of a dominant-negative version of dJNK (org-1>>bsk.DN) leads to abolishment of VLM differentiation and AM transdifferentiation. (F) Coexpression of Yki^S168A in dJNK^DN background (org-1>>bsk.DN; yki.S168A) can rescue formation of VLM fibers, but there are fewer than in wildtype, and the morphology of the VLM is severely disrupted. (G) Frequencies of observed VLM differentiation in the different genetic backgrounds. n, number of animals phenotypically classified. Coexpression of Yki^S168A can significantly rescue the phenotypes provoked by forced expression of aPKC^ΔN (n = 49, ***, P ≤ 0.001) and dJNK^DN (n = 52, ***, P ≤ 0.001). (H and H′) The in vivo AP-1 sensor TRE-GFP is activated in org-1-RFP–positive AMDCs (arrows) and (even more strongly) in org-1-RFP–negative apoptotic muscle cells (asterisks) at pupal stage P4. (I and J) Induction of CRISPR in the AMs with org-1-GAL4 against dJun [Jra]; org-1>>Cas9; t::gRNA-Jra^4x; I) or dFos [kay]; org-1>>Cas9; t::gRNA-kay^4x; J) blocks VLM differentiation and AM fragmentation (arrows). Scale bars in A–F, I, and J: 100 µm; H: 10 µm. Actin is visualized with phalloidin; DNA is visualized with DAPI.