Screen for genes regulated during early kidney morphogenesis

Kidney development starts with the reciprocal induction of mesenchymal and ureteric bud nephron formation in the mesenchyme. To identify cells which l eads to condensation, changes in gene expression during these processes, we compared differential display polymerase chain reaction (PCR) profiles of uninduced and induced mesenchymal cells. In vitro kidney development in the form of the transfilter organ culture system was used to generate homogene ous cell populations for this type of comparison. Here we describe the isol ation of known and novel genetags from this screening. Among the known gene s the ufo receptor tyrosine kinase, sFRP2, and the groucho related gene (gr g) were verified as being upregulated upon induction. With four of eight no vel genes tested, Northern blot analysis proved to be sensitive enough to c onfirm differential expression. To improve sensitivity and gain additional spatial information, in situ hybridization was performed. Expression analys is of two differential display PCR products, designated CO-5 and M2-4, demo nstrated the cell-specific and dynamic expression of these novel genetags i n the developing kidney and other tissues. CO-5 transcripts were expressed in the ureteric bud, S-shaped and in the collecting system. Signals For M2- 4, a gene not detectable Northern blot analysis, were only found in condens ing mesenchymal cells and early differentiation stages, but not in the coll ecting ducts. The large Fraction of novel genetags from the present screeni ng that have not yet been analyzed provides a rich resource to clone generi c networks regulating early nephrogenesis. (C) 1999 Wiley-Liss, inc.