Fig. 5. PRC2 inactivation causes derepression of Hox genes and lin-28.

(A) Violin plots comparing expression levels of various genes for all conditions. (B) Anti–Abd-A immunostainings in tumors of the different genotypes. Tumors are from 1-day-old adults, and tNBs are marked with anti-Mira. (C) Overexpression of abd-A in poxⁿ>pros^RNAi larvae prevents tumor induction. Tumors are restored when apoptosis is blocked by the caspase inhibitor p35 despite abd-A overexpression. Both wild-type NBs and tNBs are labeled with anti-Mira antibody (green), whereas tumor cells are identified by their expression of the NLS::mCherry (red). (D) Immunostainings in adult tumors of the different genotypes. tNBs are marked with anti-Mira. Imp⁺ tNBs are marked with anti-Imp and anti-Chinmo. In control tumors, immunostainings against Lin-28 show that Lin-28 is coexpressed with Imp and Chinmo in tNBs. In contrast, Lin-28 is ectopically expressed in some tNBs in the absence of Chinmo and Imp upon inactivation of E(z) or Su(z)12 (delineated by yellow dotted lines). (E) Scheme summarizing a model for the double-edge effect induced by the inactivation of PRC2 genes. Scale bars, 50 μm. Images are single confocal sections except for (C) representing a projection of several sections.