Nephron induction.
One of the most remarkable transformations of cells during organogenesis is the epithelial transformation of nephrogenic mesenchyme to secretory nephrons. During recent years, gene targeting and organ culture approaches have been used efficiently to resolve key molecules involved in this multistage process. Nephrons are induced by the tips of the branching ureteric bud that later forms the collecting duct network. The first signal in nephron induction is obviously maintaining the mesenchyme; the second enhances cell proliferation and brings together the set of cells that contribute to one single nephron. This stage is characterized by two types of condensations (first the cap stage and then pre-tubular condensation). The final step, epithelial transformation, is a cell-autonomous process. Although the molecular cascade in nephron induction is being resolved in the rat, the same signals seem to work less efficiently in the mouse. In the rat, fibroblast growth factor-2 maintains the nephrogenic mesenchyme; leukaemia inhibitory factor together with transforming growth factor beta-2 induce its condensation; and autocrine secretion of Wnt-4 converts it to epithelium.
Sariola
Hannu
H
Institute of Biomedicine, Developmental Biology, University of Helsinki, FIN-00014, Finland.
D000818:Animals; D005314:Embryonic and Fetal Development / Q000502:physiology; D016222:Fibroblast Growth Factor 2 / Q000502:physiology; D006131:Growth Inhibitors / Q000502:physiology; D006801:Humans; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000502:physiology; D009399:Nephrons / Q000196:embryology*; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000502:physiology; D053781:Transforming Growth Factor beta2
D006131:Growth Inhibitors; D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; C507838:Lif protein, mouse; D008222:Lymphokines; C509041:TGFB2 protein, human; D016212:Transforming Growth Factor beta; D053781:Transforming Growth Factor beta2; D016222:Fibroblast Growth Factor 2