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目的:探讨配对盒基因6 (paired box 6，PAX6)在先天性巨结肠(Hirschsprungs disease，HSCR)患儿结肠组织内低表达的分子机制。方法:选取24例HSCR患儿巨结肠根治术后痉挛段结肠组织为HSCR组，同期18例新生儿坏死性小肠结肠炎(necrotizing enterocolitis，NEC)手术切除坏死肠段两端正常结肠组织为NEC组作为对照。采用实时定量聚合酶链反应及蛋白免疫印迹法检测两组结肠组织内PAX6的表达水平，染色质免疫共沉淀-实时定量聚合酶链反应法检测两组结肠组织中PAX6启动子区组蛋白H3K9乙酰化水平及E1A结合蛋白p300 (EP300)结合水平。结果:HSCR组PAX6 mRNA和蛋白表达水平明显低于NEC组(0.13±0.05比1.08±0.45，0.41±0.12比0.82±0.12)，PAX6启动子区组蛋白H3K9乙酰化水平和EP300结合水平也明显低于NEC组(0.45±0.17比1.38±0.59，0.32±0.15比1.45±0.49 )，差异均有统计学意义(n P<0.01)。HSCR组PAX6表达水平与其启动子区组蛋白H3K9乙酰化水平成正相关(n r＝0.664，n P<0.05)，H3K9乙酰化水平与EP300结合水平成正相关(n r＝0.624，n P<0.05) 。n 结论:HSCR患儿结肠组织中PAX6低表达可能与其启动子区EP300结合减少导致H3K9乙酰化水平下调有关。“,”Objective:To study the molecular mechanism of low expression of paired box 6 (PAX6) gene in colon tissue among children with Hirschsprung’s disease (HSCR).Method:A total of 24 children with HSCR and received radical operation were selected as the HSCR group. 18 cases with neonatal necrotizing enterocolitis (NEC) received necrotizing colectomy, and the normal ends of the dissected colon were selected as the control group. Real-time polymerase chain reaction (rt-PCR) and Western blotting were used to examine the expression of PAX6 gene in the colon tissue of the HSCR group and the control group. ChIP-qPCR was used to detect the acetylation level of histone H3K9 and the binding level of E1A binding protein 300 (EP300) in the promoter region of PAX6 gene in the colon tissue among both groups.Result:Compared with the control group, the mRNA and protein expression levels of PAX6 gene in colon tissue of HSCR group were significantly decreased (0.13±0.05 vs. 1.08±0.45, 0.41±0.12 vs. 0.82±0.12, n P<0.01). Histone H3K9 acetylation level (0.45±0.17 vs. 1.38±0.59,n P<0.01) and EP300 binding level (0.32±0.15 vs. 1.45±0.49,n P<0.01) in PAX6 promoter region in the HSCR group were significantly lower than the control group. Statistically significant positive correlation existed between the expression level of PAX6 gene and the acetylation level of H3K9 in PAX6 promoter region (n r=0.664, n P<0.05), and between the acetylation level of H3K9 and the binding level of EP300 in HSCR group (n r=0.624, n P<0.05).n Conclusion:The low expression of PAX6 gene in colon tissue of children with HSCR may be due to the down regulation of H3K9 acetylation level caused by the reduction of EP300 binding level in PAX6 promoter region.