title: [Mechanism of cleft palate in mice induced by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin].
abstract: OBJECTIVE
  To explore the mechanism of cleft palate in mice induced by 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin (TCDD).
  
  
  METHODS
  On gestation day 10 (GD 10), 12 pregnant mice were randomly divided into two groups as the treated group and the control group with 6 mice in each group. The mice in the treated group received intragastric administration with 64 microg TCDD/kg, while the mice in the control group received equivalent corn oil. The embryos were examined under stereomicroscope to detect the incidence of cleft palate on GD 18.5. Another 18 pregnant mice were randomly divided into two groups (treated group and control group) on GD 10 with 9 pregnant mice in each group. Then each group was divided into 3 subgroups: GD 13.5, GD 14.5 and GD 15.5, with 3 pregnant mice in each subgroup. The palatal shelves were dissected from the embryos for RNA and DNA extraction on GD 13.5, GD 14.5 and GD 15.5. At last the expression of Smad 2-4 and Smad 7 mRNA was investigated by RT-PCR, and the TGF-beta3 promoter methylamine levels were investigated by methylation specific PCR (MSP).
  
  
  RESULTS
  The cleft palate mice model was established successfully by exposing pregnant C57BL/6J mice to TCDD. Total frequency of clefts was 100% in TCDD group, and the frequency of clefts was 0 in the control group. The relative expression of Smad 2 mRNA was 0.263 +/- 0.088, 0.296 +/- 0.016 and 0.159 +/- 0.027 in TCDD group, 0.180 +/- 0.042, 0.282 +/- 0.029 and 0.165 +/- 0.018 in control group. The relative expression of Smad 3 mRNA was 0.453 +/- 0.153, 0.551 +/- 0.160 and 0.328 +/- 0.049 in TCDD group, 0.375 +/- 0.126, 0.510 +/- 0.145 and 0.259 +/- 0.035 in control group. The relative expression of Smad 4 mRNA was 0.675 +/- 0.174, 0.577 +/- 0.070 and 0.396 +/- 0.066 in TCDD group, 0.557 +/- 0.138, 0.587 +/- 0.080 and 0.441 +/- 0.054 in control group. The relative expression of Smad 7 mRNA was 0.283 +/- 0.050, 0.320 +/- 0.068 and 0.169 +/- 0.045 in TCDD group, 0.207 +/- 0.043, 0.288 +/- 0.051 and 0.155 +/- 0.040 in control group. There was no significant difference between the TCDD treated mice and the control (P > 0.05). The TGF-beta3 promoters were at the un-methylation state both in the TCDD treated and control group.
  
  
  CONCLUSIONS
  It suggests that TCDD could induce a stable formation of cleft palate, but it is not through the TGF-beta/Smad signaling nor through the modification of TGF-beta3 promoter methylation.
authors.affiliation: Chongqing Children's Hospital, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, Chongqing Medical University, Chongqing 400014, China.
authors.forename: Ya-Lan
authors.initials: YL
authors.lastname: Pu
authors.forename: Li-Ling
authors.initials: LL
authors.lastname: Liu
authors.forename: Li-Qiang
authors.initials: LQ
authors.lastname: Gan
authors.forename: Xiao-Meng
authors.initials: XM
authors.lastname: He
authors.forename: Yue-Xian
authors.initials: YX
authors.lastname: Fu
mesh_terms: D000818:Animals; D002972:Cleft Palate / Q000139:chemically induced*; D019175:DNA Methylation; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism; D013723:Teratogens / Q000633:toxicity*; D053782:Transforming Growth Factor beta3 / Q000378:metabolism
chemical_list: D000072317:Polychlorinated Dibenzodioxins; D051785:Smad Proteins; D013723:Teratogens; C509045:Tgfb3 protein, mouse; D053782:Transforming Growth Factor beta3