A mouse line expressing Sall1-driven inducible Cre recombinase in the kidney mesenchyme.

Sall1 is expressed in the metanephric mesenchyme in the developing kidney, and mice deficient in Sall1 show kidney agenesis or dysgenesis. Sall1 is also expressed elsewhere, including in the limb buds, anus, heart, and central nervous system. Dominant-negative mutations of Sall1 in mice and humans lead to developmental defects in these organs. Here, we generated a mouse line expressing tamoxifen-inducible Cre recombinase (CreER(T2)) under the control of the endogenous Sall1 promoter. Upon tamoxifen treatment, these mice showed genomic recombination in the tissues where endogenous Sall1 is expressed. When CreER(T2) mice were crossed with the floxed Sall1 allele, tamoxifen administration during gestation led to a significant decrease in Sall1 expression and small kidneys at birth, suggesting that Sall1 functions were disrupted. Furthermore, Sall1 expression in the kidney was significantly reduced by neonatal tamoxifen treatment. The Sall1CreER(T2) mouse is a valuable tool for in vivo time-dependent and region-specific knockout and overexpression studies.