Transcription factors and apoptosis in kidney development.

The study of kidney development at the cellular and molecular levels remains an active area of nephrologic research. This review highlights recent advances in two specific areas: transcriptional control of nephrogenesis and the role of cell death in normal kidney development. The mesenchymal-epithelial conversion that occurs during kidney development requires alterations in gene expression. Some transcription factors involved in early steps in nephrogenesis have recently been identified from the effects of gene "knockout" or dysregulated expression in transgenic mice. These include the product of the Wilms' tumor suppressor gene (WT-1), a mammalian paired homologue (Pax-2), and the N-myc oncoprotein. Other proteins, including Pax-8, hepatocyte nuclear factor-1, hepatocyte nuclear factor-4, Kid-1, and formins, exhibit spatiotemporally restricted patterns of expression, homology to products of developmental control genes in Drosophila, or mutant phenotypes consistent with possible roles in nephrogenesis. During the past year, another important observation was that apoptosis (programmed cell death) occurs during normal kidney development. Studies of knockout mice suggest that Bcl-2, which protects against death in many contexts, is also involved in kidney development.