YAC transgenic analysis reveals Wilms' Tumour 1 gene activity in the proliferating coelomic epithelium, developing diaphragm and limb

Wilms' Tumour 1 gene (WT1) is required for the con ect development of the u rogenital system. To examine its regulation and expression, we created seve ral transgenic mouse lines containing a P-galactosidase reporter driven by the human WT1 promoter. A 5 kb promoter weakly recapitulated a subset of th e endogenous Wt1 expression pattern. In contrast, 470 and 280 kb YAC transg enes reproduced the correct pattern with high activity and highlighted new expression sites. Wt1 is expressed in the septum transversum revealing how its mutation causes diaphragmatic defects, Wt1 expression in the limb demar cates a zone between chondrogenic and apoptotic domains. Finally, Wt1 is ex pressed in mesenchymal cells derived from the coelomic epithelium. Based up on these and further data we discuss a Wt1 role in epithelial tt mesenchyma l transitions. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.