title: Novel regulators of kidney development from the tips of the ureteric bud.
abstract: Mammalian nephrogenesis depends on the interaction between the ureteric bud and the metanephric mesenchyme. As the ureteric bud undergoes branching and segmentation, the stalks differentiate into the collecting system of the mature kidney, while the tip cells interact with the adjacent cells of the metanephric mesenchyme, inducing their conversion into nephrons. This induction is mediated by secreted factors. For identifying novel mediators, the tips of the ureteric tree were isolated and microarray analyses were performed using manually refined, multistep gene ontology annotations. For identifying conserved factors, two databases were developed, one from mouse E12.5 and one from rat E13.5 ureteric buds. The overlap of mouse and rat data sets yielded 20 different transcripts that were enriched in the ureteric bud compared with metanephric mesenchyme and predicted to code for secreted proteins. Real-time reverse transcriptase-PCR and in situ hybridization confirmed these identifications. One of the genes that was highly specific to the ureteric bud tip was cytokine-like factor 1 (CLF-1). Recombinant CLF-1 in complex with its physiologic ligand, cardiotrophin-like cytokine (CLC), triggered phosphorylation of signal transducer and activator of transcription 3 in mesenchyme, a pathway characteristic of mesenchymal-to-epithelial conversion. Indeed, when applied to isolated rat metanephric mesenchyme, CLF-1/CLC (3 nM) induced mature nephron structures expressing glomerular and tubular markers. These results underline the power of this first comprehensive gene expression analysis of the ureteric bud tip to identify bioactive molecules.
authors.affiliation: Department of Medicine, Columbia University College of Physicians and Surgeons, 630 W. 168th Street, New York, NY 10032, USA.
authors.forename: Kai M
authors.initials: KM
authors.lastname: Schmidt-Ott
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.forename: Xia
authors.initials: X
authors.lastname: Chen
authors.forename: Howard
authors.initials: H
authors.lastname: Wang
authors.forename: Neal
authors.initials: N
authors.lastname: Paragas
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Mori
authors.forename: Jau-Yi
authors.initials: JY
authors.lastname: Li
authors.forename: Benson
authors.initials: B
authors.lastname: Lu
authors.forename: Frank
authors.initials: F
authors.lastname: Costantini
authors.forename: Mario
authors.initials: M
authors.lastname: Schiffer
authors.forename: Erwin
authors.initials: E
authors.lastname: Bottinger
authors.forename: Jonathan
authors.initials: J
authors.lastname: Barasch
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D016207:Cytokines / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology*; D030541:Databases, Genetic; D004847:Epithelial Cells / Q000502:physiology; D020869:Gene Expression Profiling; D007668:Kidney / Q000196:embryology*; D008648:Mesoderm / Q000502:physiology; D051379:Mice; D038081:Organogenesis / Q000235:genetics; D051381:Rats; D018121:Receptors, Cytokine / Q000235:genetics / Q000502:physiology*; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000502:physiology*
chemical_list: D016207:Cytokines; D004268:DNA-Binding Proteins; D018121:Receptors, Cytokine; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; C494088:Stat3 protein, rat; D015534:Trans-Activators; C121169:cardiotrophin-like cytokine; C113554:cytokine-like factor-1