Overview. The Molecular Basis of Kidney Development.

This chapter focuses on various molecules involved in the regulation of metanephrogenesis. The chapter assigns specific cellular roles to molecules based on their null or misexpression phenotypes. Lim1 encodes a LIM domain containing homeobox protein that is expressed in the early lateral plate and intermediate mesoderm of most vertebrates. Although the expression pattern suggests that Lim1 may be involved in ureteric bud formation and tubulogenesis, at the moment, it can only be implicated in differentiation of the intermediate mesoderm. Eya1 is a member of a growing family of genes that are homologous to the Drosophila eyes absent (eya) gene. Eya1 plays an essential but limited role in the regulation of mesenchymal gene activity in response to MM determinants. Pax-2 encodes a paired box-containing transcription factor expressed in multiple embryonic tissues and is expressed in the nephrogenic cord at E8.5 and maintained in the mesonephric duct and tubules. Pax-2 is also expressed in the ureter, as it invades the metanephric anlage. In addition to its role in early nephrogenesis, antisense, and misexpression, Pax-2 may play a more general role in epithelialization.