Expression of WT1 during normal human kidney development.

Wilms Tumor 1 (WT1) is a zinc finger protein, expressed by human podocytes in the adult kidney, which plays a relevant role in different phases of nephrogenesis in experimental animals. Since no data are available for specific role in the human fetal kidney, this study aimed at investigating the expression of WT1 during the different phases of nephrogenesis. To this end, the expression of WT1 was evaluated in the kidneys, from four human fetuses and two newborns. WT1 immunoreactivity was detected in all the examined kidneys, but not in the kidneys of the newborn at term. Immunostaining for WT1 was observed in podocytes of the glomeruli and in the subcapsular regions, in areas of active glomerulogenesis. The extent and the intensity of immunoreactivity for WT1 changed from one case to the next according to the different gestational age. This study confirms in human kidney the relevant role played by WT1 during nephrogenesis. Its expression pattern suggests a main role in the regulation of the process of Mesenchimal-Epithelial-Transition and in the development and maturation of podocytes. Further studies are needed to verify the correlation between the expression pattern of WT1 and that of other genes products involved in nephrogenesis, in order to better understand their relationship at protein level.