Figure 6. caHSF1 disturbs neuronal positioning without affecting differentiation.

(a–h) Mice were electroporated with pCAGIG (control) or pCAGIG-caHSF1 at E14 and stained for BrdU (injected at E15) or Cutl1 (a marker for upper layer neurons) (red or white) at P14. caHSF1-electroporated (GFP⁺) cells in the heterotopia include Cutl1⁺ and BrdU⁺ cells. Most non-electroporated BrdU⁺ neurons were localized in upper layers (layers II-IV). Arrows and an asterisk indicate disruptions in the marginal zone and pial surface above the heterotopia (b). Arrowheads indicate representative double-labelled cells (c,d,g,h). (i) The percentages of Cutl1⁺ (black) and BrdU⁺ (gray) cells within caHSF1-electroporated cells are comparable to those within control-electroporated cells, indicating that caHSF1 does not affect differentiation. Data are represented as mean±s.e.m. P=n.s. by t-test (n=5 each). (j–l) Immunostaining for NeuN (a marker for mature neurons, red or white) on the P14 cortex shows normal neuronal differentiation of caHSF1-electroporated (at E14) cells (labelled with GFP) even within the heterotopia. (m,n) BrdU⁺ caHSF1-electroporated (at E14) cells (GFP⁺) were found in deep layers at E18 (arrows). BrdU was incorporated at E15. Disruption in the cortical surface (arrowheads) was already found at E18 in some caHSF1-electroporated samples. Scale bars=0.2 (a–l) and 0.5 (m,n) mm.