title: A Molecular atlas of Xenopus respiratory system development.
abstract: BACKGROUND
  Respiratory system development is regulated by a complex series of endoderm-mesoderm interactions that are not fully understood. Recently Xenopus has emerged as an alternative model to investigate early respiratory system development, but the extent to which the morphogenesis and molecular pathways involved are conserved between Xenopus and mammals has not been systematically documented.
  
  
  RESULTS
  In this study, we provide a histological and molecular atlas of Xenopus respiratory system development, focusing on Nkx2.1+ respiratory cell fate specification in the developing foregut. We document the expression patterns of Wnt/β-catenin, fibroblast growth factor (FGF), and bone morphogenetic protein (BMP) signaling components in the foregut and show that the molecular mechanisms of respiratory lineage induction are remarkably conserved between Xenopus and mice. Finally, using several functional experiments we refine the epistatic relationships among FGF, Wnt, and BMP signaling in early Xenopus respiratory system development.
  
  
  CONCLUSIONS
  We demonstrate that Xenopus trachea and lung development, before metamorphosis, is comparable at the cellular and molecular levels to embryonic stages of mouse respiratory system development between embryonic days 8.5 and 10.5. This molecular atlas provides a fundamental starting point for further studies using Xenopus as a model to define the conserved genetic programs controlling early respiratory system development.
authors.affiliation: Division of Developmental Biology, Perinatal Institute, Cincinnati Children's Hospital, and the Department of Pediatrics, College of Medicine University of Cincinnati, Cincinnati, Ohio.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Rankin
authors.forename: Hong
authors.initials: H
authors.lastname: Thi Tran
authors.forename: Marcin
authors.initials: M
authors.lastname: Wlizla
authors.forename: Pamela
authors.initials: P
authors.lastname: Mancini
authors.forename: Emily T
authors.initials: ET
authors.lastname: Shifley
authors.forename: Sean D
authors.initials: SD
authors.lastname: Bloor
authors.forename: Lu
authors.initials: L
authors.lastname: Han
authors.forename: Kris
authors.initials: K
authors.lastname: Vleminckx
authors.forename: Susan E
authors.initials: SE
authors.lastname: Wert
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Zorn
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology*; D004843:Epistasis, Genetic / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D008675:Metamorphosis, Biological / Q000502:physiology*; D051379:Mice; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D012137:Respiratory System / Q000166:cytology / Q000196:embryology*; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D060449:Wnt Signaling Pathway / Q000502:physiology*; D029867:Xenopus Proteins; D014982:Xenopus laevis; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: C000614414:Nkx2-1 protein, mouse; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D029867:Xenopus Proteins; D051176:beta Catenin; C000614411:nkx2-1 protein, Xenopus
keywords: Nkx2.1; Xenopus; development; lung; respiratory epithelium; respiratory system; specification; trachea