title: Exogenous fibroblast growth factor-10 induces cystic lung development with altered target gene expression in the presence of heparin in cultures of embryonic rat lung.
abstract: OBJECTIVE
  Signaling by fibroblast growth factor (FGF) receptor (FGFR) 2IIIb regulates branching morphogenesis in the mammalian lung. FGFR2IIIb is primarily expressed in epithelial cells, whereas its ligands, FGF-10 and keratinocyte growth factor (KGF; FGF-7), are expressed in mesenchymal cells. FGF-10 null mice lack lungs, whereas KGF null animals have normal lung development, indicating that FGF-10 regulates lung branching morphogenesis. In this study, we determined the effects of FGF-10 on lung branching morphogenesis and accompanying gene expression in cultures of embryonic rat lungs.
  
  
  METHODS
  Embryonic day 14 rat lungs were cultured with FGF-10 (0-250 ng/ml) in the absence or presence of heparin (30 ng/ml) for 4 days. Gene expression profiles were analyzed by Affymetrix microchip array including pathway analysis. Some of these genes, functionally important in FGF-10 signaling, were further analyzed by Northern blot, real-time PCR, in situ hybridization and immunohistochemistry.
  
  
  RESULTS
  Exogenous FGF-10 inhibited branching and induced cystic lung growth only in cultures containing heparin. In total, 252 upregulated genes and 164 downregulated genes were identified, and these included Spry1 (Sprouty-1), Spry2 (Sprouty-2), Spred-1, Bmp4 (bone morphogenetic protein-4, BMP-4), Shh (sonic hedgehog, SHH), Pthlh (parathyroid hormone-related protein, PTHrP), Dusp6 (MAP kinase phosphatase-3, MKP-3) and Clic4 (chloride intracellular channel-4, CLIC-4) among the upregulated genes and Igf1 (insulin-like growth factor-1, IGF-1), Tcf21 (POD), Gyg1 (glycogenin 1), Sparc (secreted protein acidic and rich in cysteine, SPARC), Pcolce (procollagen C-endopeptidase enhancer protein, Pro CEP) and Lox (lysyl oxidase) among the downregulated genes. Gsk3β and Wnt2, which are involved in canonical Wnt signaling, were up- and downregulated, respectively.
  
  
  CONCLUSIONS
  Unlike FGF-7, FGF-10 effects on lung branching morphogenesis are heparin-dependent. Sprouty-2, BMP-4, SHH, IGF-1, SPARC and POD are known to regulate branching morphogenesis; however, potential roles of CLIC-4 and MKP-3 in lung branching morphogenesis remain to be investigated. FGF-10 may also function in regulating branching morphogenesis or inducing cystic lung growth by inhibiting Wnt2/β-catenin signaling.
authors.affiliation: Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pa., USA. sh6749@my.email.ne.jp
authors.forename: Shuichi
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakano
authors.forename: Yuko
authors.initials: Y
authors.lastname: Suguta
authors.forename: Seiko
authors.initials: S
authors.lastname: Irie
authors.forename: Luo
authors.initials: L
authors.lastname: Jianhua
authors.forename: Sikardar L
authors.initials: SL
authors.lastname: Katyal
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D051526:Fibroblast Growth Factor 10 / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D006493:Heparin / Q000378:metabolism / Q000494:pharmacology; D008168:Lung / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D009024:Morphogenesis / Q000187:drug effects / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
chemical_list: D051526:Fibroblast Growth Factor 10; D017468:Receptors, Fibroblast Growth Factor; D006493:Heparin