The role of transforming growth factor-β 2 and 3 in formation of ventral body wall in the cadmium-induced omphalocele chick model

Purpose: In the chick embryo, the administration of cadmium (Cd) induces ventral body wall defects (VBWDs) similar to the human omphalocele. Transforming growth factors beta (TGFs-beta) are involved in many developmental processes, including ventral body wall formation. The Tgf beta 2(-/-) Tgf beta 2(-/-) double knockout mice and Tgf beta 2(-/-) Tgf beta 3(+/-) mutants show VBWD, whereas Tgf beta 2(+/-) Tgf beta 2(-/-) mutants display normal ventral body wall fusion. We designed this study to investigate the messenger RNA (mRNA) levels of TGF-beta 2 and TGF-beta 3 in the Cd-induced omphalocele chick model during early embryogenesis. Methods: Chick embryos were exposed to either Cd or saline, harvested 1 hour (1H), 4H, and 8H after treatment and then divided into 2 groups: control and Cd (n = 8 at each time-point, respectively). Reverse transcription polymerase chain reaction was performed to evaluate the mRNA levels of TGF-beta 2 and TGF-beta 3 and statistically analyzed. Results: The mRNA expression levels of TGF-beta 2 at 1H were significantly decreased in the Cd group compared to controls (P < .05). However, the levels of TGF-beta 3 were not altered at all the time-points studied. Conclusion: We provide evidence, for the first time, that TGF-beta 2 gene expression is downregulated during a narrow window of early embryogenesis in the Cd chick model. Our data show that TGF-beta 2 is the key gene involved in the formation of ventral body wall. (C) 2010 Elsevier Inc. All rights reserved.