Molecular cloning of rat Wilms' tumor complementary DNA and a study of messenger RNA expression in the urogenital system and the brain.

In an effort to study the molecular basis of kidney development and carcinogenesis, we isolated complementary DNA clones of the rat homologue of the human Wilms' tumor gene, WT-1. When compared to the predicted sequence of the human WT-1 polypeptide, the rat WT-1 amino acid sequence is highly conserved (> 97%), except for the loss of one amino acid. In situ mRNA hybridization experiments localized WT-1 expression to the glomerular cells in the kidney during embryogenesis and the Sertoli cells of the testis. Similar to expression in humans and mice, WT-1 mRNA expression in the rat kidney and testis is developmentally regulated. In addition, two novel sites of specific high level WT-1 mRNA expression were seen. One is an area in the spinal cord where high level expression occurs throughout embryonic development. The second is the area postrema in the brain where localized expression continues through adulthood, suggesting a functional role for WT-1 in rat brain.