Fig. 3. Inhibition of Dpp signaling pathway by overexpression of Dad impairs cell proliferation and tissue growth. (A) Cell doubling times of Dad-expressing cells and control cells. Left panels correspond to confocal images showing GFP marked cells. Clones in the medial area of the tissue were recovered only when the apoptotic inhibitor p35 was co-expressed. The big cell clone in the -p35 experiment corresponds to a clone in the peripodial membrane and not to a clone in the columnar epithelium. Histogram nomenclature and color code as in Fig. 2B. Dad-expressing cells (gray bars) divide more slowly than do wild-type cells (black bars). Medial cells divided with a 22% longer cell cycle (3.4 hours longer, from 15.3 to 18.7 hours doubling time). (B) A9 Gal4 driver was used to express Dad or Tkv^QD throughout most of the wing disc. Cells were visualized by Hoechst 33258 DNA stain. Dad expression causes a reduction of the disc size (58% of wild-type size, n=7; Dad n=10, P<0.001), mainly along the AP axis. Conversely, Tkv^QD expression promotes enlargement of the disc (154% compared with wild-type size, n=7; Tkv^QD n=5, P<0.001). Deltavision images were acquired at the same magnification. Scale bars: 100 µm.

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