Figure 7. Forced Yap expression reverses LPA-induced cellular defects.

(a) LPA injection into the lateral ventricle at E13.5 produces changes analogous to those of the Yap CKO at P0: decreased Yap expression in ependymal cells along the aqueduct. (b) At E15.5, Yap is already decreased in the cytoplasm/junction of ependymal cell precursors, but nuclear Yap is present in a subset of apical lining cells (arrows) in the LPA-treated embryos. (c) pYap proteins are undetectable in the ventral aqueduct in the Yap CKO at E15.5 (arrow head). (d) Following LPA administration at E13.5, nuclear shape becomes rounder (length to width ratio close to 1 (1.3), than in control HBSS-treated animals (2.5). (e) Many BrdU (+) S-phase cells are scattered outside of VZ in mice receiving LPA, compared with control. (f) On electroporation, GFP-Yap fusion protein recapitulates Yap localization in nucleus, junction and cytoplasm. (g–i) GFP-Yap electroporated into the aqueduct before LPA injection into a lateral ventricle restore Sox9 expression and apical attachment to levels comparable to those of HBSS-treated control cells. Quantification of BrdU (+), GFP (+) or Sox9 (+) and GFP (+) cells was done by counting single- or double-positive cells in the images (n=3). Two-tailed unpaired t-test reveals statistical significance (**P<0.01 and *P<0.05). Error bar represent mean+s.e.m.; n=3. Scale bars, 1 mm (a); 50 μm (b,c); 50 and 10 μm (g).