Fig. 7. Gli3 is required for SMO-dependent control of GLI expression and kidney development. (A) Western analysis of kidney tissue lysates using GLI-specific antibodies. Embryonic kidneys were harvested from wild-type or Gli3^–/– mice at E11.5 and cultured in the presence of drug vehicle or cyclopamine for 4 days. Treatment of kidneys isolated from wild-type mice with cyclopamine markedly decreased GLI1 and GLI2. This inhibitory effect was totally abrogated in Gli3-deficient mice. (B) Ureteric bud branching in cultured kidney explants. Treatment of kidneys isolated from E11.5 wild-type mice with cyclopamine decreased the number of ureteric bud branches identified by Dolichos Biflorus Agglutinin. This inhibitory effect was abrogated in Gli3-deficient mice. (C) Model of GLI3 activity in a state of SMO inhibition. Decreased SMO activity generated by SHH deficiency or treatment with cyclopamine increases formation of GLI3 repressor. GLI3 repressor controls expression of Gli1 and Gli2 as well as SHH target genes that control renal morphogenesis (Pax2 and Sall1) and cell proliferation (cyclin D1 and Mycn).