Volume 18, Number 2, June 2006

Effect of 2,3,7,8-Tetrachlorodibenzo-p-dioxin on Cleft Palate-related Genes in Mouse Embryonic Palatal Mesenchymal Cells

Tomohiro Yamada, Katsuaki Mishima, Kumiko Fujiwara, Hideto Imura, Norifumi Moritani,
Toshio Sugahara
Oral and Maxillofacial Reconstructive Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science, Okayama , Japan .

Abstract
Objective: To investigate the possible involvement of 2,3,7,8-tetrachlorodibenzo- p -dioxin in the pathogenesis of cleft palate in mouse palatal cells.
Materials and Methods: Palatal shelves of gestation day 12.5 ICR mouse foetuses were removed and cultured with serum. One day after the second passage, the medium was changed to serum-free and 2,3,7,8-tetrachlorodibenzo-p-dioxin was added at 1 ng/mL, 10 ng/mL, and 100 ng/mL. After culture for 1 and 3 hours, all cellular RNA was isolated from the cells. Expression of some cleft palate-related genes was analysed semiquantitatively using reverse transcriptase-polymerase chain reaction. Five genes (Tgfb3, Msx1, Lhx8, Fgfr1, and Fgfr2) were selected on the basis that functional disturbance of these genes causes cleft palate with high frequency. The data were compared with GAPDH.
Results: In the first passage, many mouse embryonic palatal mesenchymal cells had spread out, and a number of monolayer spindle-shaped cells were identified. The cells were stable in the second passage and also in the serum-free medium. One hour after addition of 2,3,7,8-tetrachlorodibenzo- p -dioxin, Tgfb3 mRNA expression was reduced at a concentration of 100 ng/mL. After 3 hours, Tgfb3, Msx1, and Lhx8 mRNA expression were also reduced. However, there was no effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the gene expression for Fgfr1 and Fgfr2 mRNA.
Conclusion: 2,3,7,8-Tetrachlorodibenzo-p-dioxin may contribute to the induction of cleft palate by suppressing Tgfb3, Msx1, and Lhx8 gene expression.

Key words: Cleft palate, Dioxins, Polymerase chain reaction, Tetrachlorodibenzodioxin

Asian J Oral Maxillofac Surg. 2006;18:93-8.
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