TTF-1 and HNF-3beta in the developing tracheoesophageal fistula: further evidence for the respiratory origin of the distal esophagus'.
OBJECTIVE
Using an established rat model of esophageal atresia with tracheoesophageal fistula (EA-TEF), the authors have studied the organogenesis of this congenital anomaly. The authors previously have proposed that the "distal esophagus" actually is of respiratory lineage. In this report this hypothesis is tested by examining the expression of two foregut patterning transcription factors, thyroid transcription factor-1 (TTF-1) and hepatocyte nuclear factor-3beta (HNF-3beta), within the developing TEF.


METHODS
Pregnant Sprague-Dawley rats were injected with 2.2 mg/kg of Adriamycin intraperitoneally on days 6 to 9 of gestation. Using microdissection, the trachea, blind-ending esophagus, TEF, and stomach were isolated from embryos of various gestional ages. Immunohistochemistry was performed using polyclonal antibodies to TTF-1 and HNF-3beta.


RESULTS
TTF-1 is a homeodomain protein that previously has been shown to be expressed in the lung and trachea but not in the gastrointestinal tract, and which, when deleted in a developing lung, results in a mouse with no peripheral lung parenchyma. TTF-1 was expressed strongly in the lung, fistula, and distal esophagus, but not in the proximal esophagus. HNF-3beta is a forkhead transcription factor important in foregut patterning that binds and activates the TTF-1 promotor sequence. HNF-3beta was expressed globally in the fistula and lung as well as the esophagus.


CONCLUSIONS
The expression of the lung-specific transcription factor TTF-1 within the TEF strongly implies that the "distal esophagus" is a respiratory-derived structure and thus supports our theory of TEF organogenesis. The conservation of HNF-3beta expression both in the TEF as well as the normal developing trachea and esophagus suggests that global foregut patterning is intact in the formation of this anomaly, and the defect lies at the level of the respiratory versus gastrointestinal commitment.
Crisera
C A
CA
New York University Medical Center, NY 10016, USA.
Connelly
P R
PR
Marmureanu
A R
AR
Li
M
M
Rose
M I
MI
Longaker
M T
MT
Gittes
G K
GK
D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004195:Disease Models, Animal; D005314:Embryonic and Fetal Development; D004947:Esophagus / Q000196:embryology*; D005260:Female; D051542:Hepatocyte Nuclear Factor 3-beta; D018398:Homeodomain Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D008168:Lung / Q000196:embryology; D009687:Nuclear Proteins / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012137:Respiratory System / Q000196:embryology*; D000074482:Thyroid Nuclear Factor 1; D014132:Trachea / Q000196:embryology; D014138:Tracheoesophageal Fistula / Q000196:embryology*; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; C496504:Foxa2 protein, rat; D018398:Homeodomain Proteins; C000614414:Nkx2-1 protein, mouse; C000614416:Nkx2-1 protein, rat; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D051542:Hepatocyte Nuclear Factor 3-beta