Murine nitrofen-induced pulmonary hypoplasia does not involve induction of TGF-beta signaling.
OBJECTIVE
In the murine nitrofen-induced model of congenital diaphragmatic hernia (CDH), the lungs are primarily hypoplastic and immature even before diaphragmatic closure. Because excess transforming growth factor-beta (TGF-beta) signaling induces pulmonary hypoplasia, the authors hypothesized that primary hypoplasia after nitrofen exposure may be caused by aberrant signaling by the TGF-beta pathway. Therefore, abrogation of TGF-beta signaling might rescue the hypoplasia.


METHODS
The authors performed intratracheal microinjections of a recombinant adenoviral vector encoding a dominant-negative TGF-beta type II receptor (AdIIR-DN) in nitrofen-exposed and control E12 mouse lungs, which then were cultured for 4 days in serumless chemically defined media. The mRNA expression of Smad2, 3, 4, and 7 in nitrofen-exposed and control E12 lungs after 4 days in culture were compared.


RESULTS
ADIIR-DN increased terminal branching in control lungs by 28% compared with lungs injected with control virus (61.8 +/- 4.6 v. 48.4 +/- 4.7, P =.004). However, there was no difference between nitrofen-exposed lungs injected with ADIIR-DN and those injected with control virus. Compared with control lungs, Smad mRNA expression was decreased markedly in nitrofen-exposed lungs: Smad2 (40%, P =.16), Smad3 (29%, P =.02), Smad4 (25%, P =.07), and Smad7 (36%, P =.04).


CONCLUSIONS
Because abrogation of TGF-beta signaling does not rescue the hypoplasia seen in the nitrofen model, and Smad expression is decreased in nitrofen-exposed lungs, the TGF-beta pathway does not appear to play a role in nitrofen-induced pulmonary hypoplasia.
Leinwand
Michael J
MJ
Division of Pediatric Surgery, Childrens Hospital Los Angeles Research Institute and Center for Craniofacial and Molecular Biology, University of Southern California Schools of Medicine and Dentistry, Los Angeles, CA, USA.
Zhao
Jingsong
J
Tefft
J Denise
JD
Anderson
Kathryn D
KD
Warburton
David
D
D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics; D015870:Gene Expression; D006548:Hernia, Diaphragmatic / Q000139:chemically induced / Q000378:metabolism*; D008168:Lung / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D009924:Organ Culture Techniques; D010647:Phenyl Ethers; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction; D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D051906:Smad7 Protein; D015534:Trans-Activators / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D004268:DNA-Binding Proteins; D010647:Phenyl Ethers; D012333:RNA, Messenger; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; D051906:Smad7 Protein; C497807:Smad7 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; C007350:nitrofen