Figure 7.

PKC overactivation in EpCAM-depleted embryos, and enhanced activation at the ectoderm–mesoderm boundary. (A–F) Cryosections of ectoderm explants stained with an antibody recognizing phosphorylated PKC substrates. (A) Control, with weak signal at the cell periphery (large arrows), in the nucleus (small arrow), and at the nuclear membrane (arrowheads). Note that not all nuclei are visible on one section. (B) Bright signal in EpCAM-depleted cells, including a prominent signal at the periphery (large arrows) and at the nuclear membrane (arrowheads). (C–E) Strong decrease after treatment of EpCAM-depleted explants with chelerythrine chloride (ChelCl, inhibitor of classical and novel PKCs), PKC-ε peptide inhibitor, or expression of dominant-negative PKC-δ. (F) Partial selective decrease (mostly cytoplasm and nuclear membrane) after treatment with Gö6976 (classical PKCs). (G and G′) Dorsal region of stage 10.5 whole-embryo section double-stained for C-cadherin (G, red channel), and phospho-PKC substrates (G′, green channel; including enlarged areas and corresponding pseudocolors). Nuclei were counterstained with Hoechst (not depicted). Exposure is higher than for panels A–F. The signal tends to be enriched along parts of Brachet’s cleft (arrowheads). Other bright signals correspond mainly to nuclei and mitotic structures (small arrows).