title: Smad1 and WIF1 genes are downregulated during saccular stage of lung development in the nitrofen rat model.
abstract: OBJECTIVE
  The exact pathogenesis of pulmonary hypoplasia in the nitrofen-induced congenital diaphragmatic hernia (CDH) still remains unclear. Smad1, one of the bone morphogenesis protein (BMP) receptor downstream signaling proteins, plays a key role in organogenesis including lung development and maturation. Smad1 knockout mice display reduced sacculation, an important feature of pulmonary hypoplasia. Wnt inhibitor factor 1 (Wif1) is a target gene of Smad1 in the developing lung epithelial cells (LECs). Smad1 directly regulates Wif1 gene expression and blockade of Smad1 function in fetal LECs is reported to downregulate Wif1 gene expression. We designed this study to test the hypothesis that pulmonary Smad1 and Wif1 gene expression is downregulated during saccular stage of lung development in the nitrofen CDH model.
  
  
  METHODS
  Pregnant rats were exposed to either olive oil or nitrofen on day 9 of gestation (D9). Fetuses were harvested on D18, and D21. Fetal lungs were dissected and divided into 2 groups: control and nitrofen (n = 9 at each time point, respectively). Pulmonary gene expression of Smad1 and Wif1 were analyzed by real-time RT-PCR. Immunohistochemistry was performed to evaluate protein expression/distribution of Smad1 and Wif1.
  
  
  RESULTS
  The relative mRNA expression levels of Smad1 and Wif1 were significantly downregulated in the nitrofen group compared to controls on D18 and D21 (*p < 0.01, **p < 0.05). Immunoreactivity of Smad1 and Wif1 was also markedly decreased in nitrofen lungs compared to controls on D18 and D21.
  
  
  CONCLUSIONS
  We provide evidence, for the first time, that the pulmonary gene expression of Smad1 and Wif1 is downregulated on D18 and D21 (saccular stage of lung development) in the nitrofen-induced hypoplastic lung. These findings suggest that the downregulation of Smad1/Wif1 gene expression may contribute to pulmonary hypoplasia in the nitrofen CDH model by retardation of lung development during saccular stage.
authors: National Children's Research Centre, Our Lady's Children Hospital, Dublin 12, Ireland.
authors: Naho
authors: N
authors: Fujiwara
authors: Takashi
authors: T
authors: Doi
authors: Jan-Hendrik
authors: JH
authors: Gosemann
authors: Balazs
authors: B
authors: Kutasy
authors: Florian
authors: F
authors: Friedmacher
authors: Prem
authors: P
authors: Puri
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D015536:Down-Regulation; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006548:Hernia, Diaphragmatic / Q000139:chemically induced / Q000150:complications / Q000235:genetics; D065630:Hernias, Diaphragmatic, Congenital; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics*; D008168:Lung / Q000002:abnormalities / Q000196:embryology* / Q000378:metabolism; D008171:Lung Diseases / Q000151:congenital / Q000196:embryology / Q000235:genetics; D038081:Organogenesis / Q000235:genetics; D011247:Pregnancy; D011270:Pregnancy, Animal; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051898:Smad1 Protein / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D016326:Extracellular Matrix Proteins; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D051898:Smad1 Protein; C497400:Smad1 protein, rat; C521045:Wif1 protein, rat