title: Smad expression during kidney development.
abstract: Signaling by the transforming growth factor (TGF)-beta superfamily is important during kidney development. Here, we describe the spatial and temporal expression patterns of the Smads, the transcription factors that translate TGF- signals into gene expression. RT-PCR data and in situ hybridization analysis showed that the receptor-regulated (R) Smads (Smad1, -2, -3, -5, and -8), the common partner Smad (Smad4), and the inhibitory (I) Smads (Smad6 and -7) were all expressed during mouse kidney development from embryonic day 12 until the end of nephrogenesis at postnatal day 15. Each Smad had a distinct spatial distribution. All were expressed by mesenchymal cells in the nephrogenic zone and were downregulated once these cells began to epithelialize. The common partner Smad, Smad4, was present in uninduced mesenchymal cells and at ureteric bud tips. The bone morphogenetic-responsive R-Smads, Smad1, -5, and -8, were mainly expressed in the nephrogenic zone, whereas the TGF-- responsive R-Smads were predominantly noted in the medullary interstitium. Expression of the I-Smad Smad7 was also seen in mesenchymal cells in the interstitium. Based on the observed patterns of expression, we speculate that individual or combinations of Smads may play specific roles in cell-fate determination during kidney development.
authors.affiliation: Montreal Children's Hospital, 2300 Tupper St., Montreal, Quebec, Canada H3H 1P3.
authors.forename: P
authors.initials: P
authors.lastname: Vrljicak
authors.forename: D
authors.initials: D
authors.lastname: Myburgh
authors.forename: A K
authors.initials: AK
authors.lastname: Ryan
authors.forename: M A
authors.initials: MA
authors.lastname: van Rooijen
authors.forename: C L
authors.initials: CL
authors.lastname: Mummery
authors.forename: I R
authors.initials: IR
authors.lastname: Gupta
mesh_terms: D000818:Animals; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007668:Kidney / Q000196:embryology* / Q000502:physiology*; D008648:Mesoderm / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D010750:Phosphoproteins / Q000235:genetics; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D051899:Smad2 Protein; D051900:Smad3 Protein; D051902:Smad5 Protein; D051904:Smad8 Protein; D015534:Trans-Activators / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1
chemical_list: C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051902:Smad5 Protein; C497798:Smad5 protein, mouse; D051904:Smad8 Protein; C491621:Smad9 protein, mouse; C508961:Tgfb1 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1