Abstract: Objective：To investigate the changes of methylation and histone H3K9 acetylation in CpG sites of cardiac-specific transcriptor factors GATA binding protein 4 (GATA4) and NK2 homeobox 5 (Nkx2.5) gene promotors induced by zinc deficiency during pregnancy in rats. Methods: SD rats were randomized into either of the zinc deficient group, zinc sufficient group or paired feeding group (n=9 for each group). The rats in the three groups were fed by feedstuff which contains 2.8, 29.8 or 29.8 μg zinc element per gram, respectively. The quantity of feedstuff uptaken by the rats from the paired feeding group was comparable to that from the zinc deficient group. Copulation was performed 14 days after the zinc-deprived treatment began, and the same feedstuff feeding procedure was stretched till gestation day 19. The fetal hearts were then harvested. Zinc concentrations in the fetal blood and cardiac tissues were quantified. Levels of methylation and histone H3K9 acetylation in CpG sites of GATA4 and Nkx2.5 gene promotors were assayed. Results: ①The zinc levels in the blood were significantly different among the three groups. It was significantly lower in the zinc deficient group than in the zinc sufficient group (P＜0.001) and paired feeding group (P=0.014), and there was no significantly difference between the paired feeding group and zinc sufficient group (P=0.109). ②Levels of methylation in the promotor CpG sites for GATA4 and Nkx2.5 genes were significantly different among the three groups(P＜0.05). Level of methylation in the zinc deficient group was significantly higher than that in the zinc sufficient group (P=0.005; P=0.024) or paired feeding group (P＜0.001; P=0.029), whereas no significant difference was found between the paired feeding group and zinc sufficient group (P=0.497; P=0.929). ③Levels of histone H3K9 acetylation in the promotor CpG sites for GATA4 and Nkx2.5 genes were significantly different among the three groups, which were significantly lower in the zinc deficient group than those in the zinc sufficient group (P=0.018; P=0.033) or paired feeding group (P=0.007; P=0.007). No significant difference was found in these parameters between the paired feeding group and zinc sufficient group (P=0.701; P=0.512). Conclusions: The results indicate that zinc deficiency during pregnancy could induce alterations of methylation and histone H3K9 acetylation in CpG sites of GATA4 and Nkx2.5 gene promotors, which suggests a possible role of epigenetic mechanisms of cardiac transcription factors in the fetal heart maldevelopment induced by zinc deficiency during pregnancy.

Key words: Zinc deficiency, Heart defects, congenital, Pregnant women, GATA4 transcription factor, Nkx2.5