Hoxd-13 expression in the development of hindgut in ethylenethiourea-exposed fetal rats.
OBJECTIVE
Hoxd-13, as one of the most posterior genes among Hox genes, was reported to play a critical role in the development of the most posterior alimentary canal in vertebrates. This study investigated the expression pattern of Hoxd-13 in the hindgut development of the normal and ethylenethiourea (ETU)-exposed rat embryos with anorectal malformations (ARMs) to find out the possible role of Hoxd-13 in the hindgut development and anorectal morphogenesis.


METHODS
The ETU murine model of ARMs was used via ETU 1% (125 mg/kg) on gestational day (gD) 10. Embryos were harvested via cesarean delivery on gD13 to gD21. Temporal and spatial expression of Hoxd-13 was evaluated in the normal fetal rats (n = 215) and ARMs rats (n = 218) using immunohistochemistry staining, reverse transcriptase polymerase chain reaction, and Western blot analysis.


RESULTS
Immunohistochemistry staining revealed that Hoxd-13 expression was confined to the epithelium of the hindgut, cloacal membrane, and urogenital sinus as well as the mesenchyme of the urorectal septum at all gestations in the normal group; however, in the ARMs group, the signal specific for Hoxd-13 was weak in the epithelium of the hindgut and cloacal membrane as well as the mesenchyme of the urorectal septum. Western blot analysis and reverse transcriptase polymerase chain reaction revealed that the level of Hoxd-13 expression was significantly decreased in the ARMs embryos compared with that in the normal embryos on gD13 to gD16 (P < .05) rather than on gD18 to gD21.


CONCLUSIONS
The aberrations in spatiotemporal expression pattern of Hoxd-13 on gD13 to gD16 suggested that Hoxd-13 may be an essential inductive signal for normal development of the hindgut, and altered expression may contribute to the abnormal development of the hindgut and accordingly lead to ARMs.
Dan
Zhang
Z
Department of Pediatric Surgery, The Second Affiliated Hospital, China Medical University, Shenyang 110004, PR China.
Bo
Zhang Zhi
ZZ
Tao
Zhang
Z
Wei
Zhang Shi
ZS
Jia
Wang Da
WD
Cheng
Zhang Shu
ZS
Wei
Yuan Zheng
YZ
Wang
Wei-Lin
WL
D001003:Anal Canal / Q000002:abnormalities* / Q000196:embryology; D000818:Animals; D015153:Blotting, Western; D004065:Digestive System Abnormalities / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D005031:Ethylenethiourea; D005260:Female; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012007:Rectum / Q000002:abnormalities* / Q000196:embryology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D018398:Homeodomain Proteins; D014157:Transcription Factors; D005031:Ethylenethiourea