Spatiotemporal alteration in phosphatidylinositide 3-kinase-serine/threonine protein kinase B signaling in the nitrofen-induced hypoplastic lung.
OBJECTIVE
The pathogenesis of pulmonary hypoplasia in congenital diaphragmatic hernia (CDH) is not fully understood. The serine/threonine protein kinase B (AKT) plays important roles for lung morphogenesis through epithelial-mesenchymal interaction in phosphatidylinositide 3-kinase (PI3K)-dependent manner. It has been reported that the lung explant morphogenesis in mice is interfered by inhibitors of the PI3K-AKT pathway. We hypothesized that PI3K and AKT gene and protein expression/distribution are altered during epithelial morphogenesis in the nitrofen-induced hypoplastic lung.


METHODS
Pregnant rats were exposed to either olive oil or nitrofen on day 9 of gestation (D9). Fetal lungs were harvested on D15, D18, and D21 and divided into 3 groups as follows: control, nitrofen with CDH (CDH[-]), and nitrofen without CDH (CDH[+]) (n = 8 at each time-point, respectively). Reverse transcription polymerase chain reaction and immunohistochemistry were performed.


RESULTS
Messenger RNA expression levels of PI3K at D21 was significantly decreased in CDH(-) and CDH(+) group (5.71 +/- 0.85 and 6.80 +/- 0.88, respectively) compared to controls (8.95 +/- 3.22; P < .05). Messenger RNA levels of AKT were also significantly decreased at D18 in CDH(-) and CDH(+) lungs (1.21 +/- 0.16 and 1.20 +/- 0.32, respectively) compared to controls (1.62 +/- 0.14; P < .01). The PI3K immunoreactivity was diminished in the distal epithelium at D18 and decreased in the overall intensity at D21 in hypoplastic lungs compared to controls. The AKT immunoreactivity was decreased in mesenchyme at D18 and decreased overall intensity at D21 in CDH lungs compared to controls.


CONCLUSIONS
Spatiotemporal alteration of pulmonary PI3K and AKT gene and protein expression during epithelial morphogenesis may interfere with epithelial-mesenchymal interaction, causing pulmonary hypoplasia in CDH by disrupting PI3K-AKT signaling pathway.
Doi
Takashi
T
The Children's Research Center, Our Lady's Children's Hospital, Dublin 12, Ireland.
Ruttenstock
Elke
E
Dingemann
Jens
J
Puri
Prem
P
D000818:Animals; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000235:genetics; D005260:Female; D005315:Fetal Diseases / Q000235:genetics / Q000378:metabolism; D005325:Fetal Organ Maturity / Q000235:genetics; D007839:Functional Laterality; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D006548:Hernia, Diaphragmatic / Q000139:chemically induced* / Q000378:metabolism*; D065630:Hernias, Diaphragmatic, Congenital; D007150:Immunohistochemistry; D008168:Lung / Q000002:abnormalities* / Q000196:embryology / Q000378:metabolism*; D051379:Mice; D009024:Morphogenesis / Q000235:genetics; D010647:Phenyl Ethers; D011247:Pregnancy; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D010647:Phenyl Ethers; D014157:Transcription Factors; C076224:RSU1 protein, human; D051057:Proto-Oncogene Proteins c-akt; C007350:nitrofen