Fig. 4. Alteration of HD protein gene expressions by Pax6 misexpression. (A-F) pCAX-mPax6 was introduced into the hindbrain of wild-type embryos at 22-somite stage, and the embryo was cultured for 26 hours. Serial sections obtained from the same electroporated embryo. Exogenous Pax6 is detected in the right side of the hindbrain at a high level, while endogenous Pax6 is seen in both sides (A). Note repression of Nkx2.2 expression (bracket in B) and ectopic expression of Irx3, Dbx2 and Dbx1 induced in the area where pCAX-mPax6 is transferred (arrowheads in D-F). Expression of Nkx6.1 is not changed by Pax6 overexpression (C). (G-L) pCAX-mPax6 was introduced into the hindbrain of Pax6 mutant embryos at 22-somite stage, and the embryo was cultured for 30 hours (corresponding to E12.5) as neuronal differentiation is slightly delayed in the mutant. Serial sections obtained from the same electroporated embryo. Exogenous Pax6 is detected in the right side at a high level (G). Note that expression of Nkx2.2 is downregulated (bracket in H), and ectopic expression of Dbx2 and Dbx1 is observed in the electroporated area (arrowheads in K,L). Expression of Nkx6.1 seems unchanged by Pax6 electroporation into the mutant hindbrain (I). Induction of Irx3 is not detected, as Irx3 expression shifts ventrally in the Pax6 mutant hindbrain (J).
