Fig. 5. Hoxd12 converts Gli3 repressor into an activator. (A,B) A 4 kb Ptc promoter/luciferase reporter (0.5 µg,) was co-transfected with varying amounts of Gli3 TR repressor (5-80 ng), with or without 25 ng of full-length Hoxd12 wild type (wt; A) or homeodomain mutant (mt; B). (C) Delta-crystallin basal promoter with eight Gli consensus elements (8xGli)/luciferase (1.5 µg) co-transfected with full-length mt Hoxd12 (25 ng) and varying amounts of Gli3 TR (2.5-20 ng). (D) The transfection results are most consistent with a model in which Gli3 recruits Hoxd12 to Gli3-target DNA-binding sites, and the bound Hoxd12 converts Gli3 TR into an activator of the Gli3-target promoters in a stoichiometric fashion that is independent of Hoxd12 DNA binding.