Lgr4-deficient mice showed premature differentiation of ureteric bud with reduced expression of Wnt effector Lef1 and Gata3

We previously reported that Lgr4 has a critical role in the morphogenesis of kidney, but the detailed functions of Lgr4 in kidney development have not been elucidated. In contrast to Lgr4 null mice with 129Ola × C57BL/6J mixed background, C57BL/6J-backcrossed Lgr4 null mice (Lgr4^-/-) showed the severe phenotype of embryonic lethality and also had dilated tubules in kidneys at E16.5. Based on quantitative RT-PCR and in situ hybridization, branching morphogenesis at E15.5 in the Lgr4^-/- was arrested earlier, and both DBA-lectin staining and immunohistochemical analysis using Aqp3 antibodies showed that the ureteric bud (UB) of Lgr4^-/- kidneys underwent premature differentiation. Furthermore, quantitative RT-PCR and histological analysis suggested that the impaired UB differentiation was caused by down-regulation of the Wnt pathway and Gata3 in the Lgr4^-/- kidneys. We demonstrate here that Lgr4 has a novel function for maintaining the UB in an undifferentiated state.