The Effect Of Transforming Growth Factor-β3in Cleft Palate Of Mice Induced By2,3,7,8-tetrachlorodibenzodioxin

Objective: To explore the effect of transforming growth factor-β3(TGF-β3) in cleft palate of mice induced by2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD).Methods: Each female mouse was mated overnight with a malemouse, and noon of the day on which a vaginal plug was found, wasappointed as gestation day0(GD0). On GD10, the pregnant mice wererandomly divided into two groups: the treated group mice were dosed with64μg TCDD/kg body weight, while the control group mice receivedequivalent corn oil. The embryos were examined under stereomicroscope todetect the incidence of cleft palate on GD18.5, and the palatal shelves weredissected from the embryos for DNA, RNA and protein extraction onGD13.5, GD14.5and GD15.5. At last the expression of TGF-β3wasinvestigated by reverse transcription polymerase chain reaction (RT-PCR)and Western blot, the expression of Smad2-4and Smad7mRNA wasinvestigated by RT-PCR, and the TGF-β3promoter methylamine levelswere investigated by Methylmion Specific PCR (MSP).Results: The cleft palate mice model was established successfully by exposing pregnant C57BL/6mice to TCDD. Total frequency of clefts was100%in TCDD group, and the frequency of clefts was0%in the controlgroup, there was significant difference between the TCDD group and thecontrol (P<0.05). The expression of TGF-β3were gradually up-regulated inTCDD group on GD13.5, GD14.5and GD15.5, through RT-PCR andwestern blot(P＜0.05). There were no significant difference in theexpressions of Smad2-4and Smad7mRNA between the TCDD treatedmice and the control. The TGF-β3promoters were at the unmethylationstate both in the TCDD treated group and the control.Conclusion: Our study suggested that TCDD could induce a stableformation of cleft palate and up-regulat the expression of TGF-β3, and theover expression of TGF-β3might be a key signal pathway resulting inTCDD-induced cleft palate, but it was not through the TGF-β/Smadsignaling nor through the modification of TGF-β3promoter methylation.