Nicotine induced CpG methylation of Pax6 binding motif in StAR promoter reduces the gene expression and cortisol production.
Nicotine induced CpG methylation of Pax6 binding motif in StAR promoter reduces the gene expression and cortisol production.
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DOI：
10.1016/j.taap.2011.09.016
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发表时间：
2011-12-15
影响因子：
3.8
通讯作者：
Wang H
中科院分区：
文献类型：
--
作者：
Wang T;Chen M;Liu L;Cheng H;Yan YE;Feng YH;Wang H
类固醇急性调节蛋白（StAR）介导类固醇激素合成的限速步骤，对胎儿发育至关重要。我们报道了在尼古丁诱导的宫内生长迟缓（IUGR）大鼠模型中胎儿肾上腺中的StAR表达被抑制。本研究利用人胎儿肾上腺皮质（pHFAC）原代细胞和人胎儿肾上腺细胞系NCI-H295A，我们发现尼古丁以剂量和时间依赖的方式抑制StAR的表达和皮质醇的产生，并在尼古丁治疗终止后的5代内延长对细胞增殖的抑制作用。StAR启动子区域的甲基化检测发现，nt - 377位点的CpG甲基化对尼古丁治疗敏感。尼古丁诱导的这一点甲基化频率的改变与StAR表达水平密切相关，表明该位点在调节StAR表达中起重要作用。利用生物信息学分析和siRNA方法的进一步研究表明，单个CpG位点是StAR启动子中Pax6结合基序（CGCCTGA）的一部分。荧光素酶活性分析证实Pax6通过结合胰高血糖素g3样基序（CGCCTGA）增加StAR基因的表达，该位点的甲基化阻断Pax6的结合，从而抑制StAR基因的表达。这些数据在StAR启动子的Pax6结合基序上发现了一个尼古丁敏感的CpG位点，该位点可能在调节StAR表达中起核心作用。研究结果表明，一种表观遗传机制可以解释尼古丁如何通过胎儿编程导致成人疾病或代谢综合征等紊乱。
Steroidogenic acute regulatory protein (StAR) mediates the rate-limiting step in the synthesis of steroid hormones, essential to fetal development. We have reported that the StAR expression in fetal adrenal is inhibited in a rat model of nicotine-induced intrauterine growth retardation (IUGR). Here using primary human fetal adrenal cortex (pHFAC) cells and a human fetal adrenal cell line NCI-H295A, we show that nicotine inhibits StAR expression and cortisol production in a dose- and time-dependent manner, and prolongs the inhibitory effect on cells proliferating over 5 passages after termination of nicotine treatment. Methylation detection within the StAR promoter region uncovers a single site CpG methylation at nt −377 that is sensitive to nicotine treatment. Nicotine-induced alterations in frequency of this point methylation correlates well with the levels of StAR expression, suggesting an important role of the single site in regulating StAR expression. Further studies using bioinformatics analysis and siRNA approach reveal that the single CpG site is part of the Pax6 binding motif (CGCCTGA) in the StAR promoter. The luciferase activity assays validate that Pax6 increases StAR gene expression by binding to the glucagon G3-like motif (CGCCTGA) and methylation of this site blocks Pax6 binding and thus suppresses StAR expression. These data identify a nicotine-sensitive CpG site at the Pax6 binding motif in the StAR promoter that may play a central role in regulating StAR expression. The results suggest an epigenetic mechanism that may explain how nicotine contributes to onset of adult diseases or disorders such as metabolic syndrome via fetal programming.
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