2012年9月18日 电 /生物谷BIOON/ --据发表在PLoS ONE杂志上的一项研究证实，一个众所周知的环境污染物二恶英可以改变生理功能。
南加州大学医学院Narendra Singh、Mitzi Nagarkatti和Prakash Nagarkatti研究团队证实，实验小鼠模型在怀孕期间暴露于二恶英（TCDD）下，二恶英对胎儿可能有显著毒性影响，尤其是对发挥抵抗感染作用的免疫细胞毒性作用更强。他们发现二恶英会改变小分子RNA，进而影响到大量基因的表达。
该研究分析了608个小分子RNA，其中78个microRNAs被二恶英显著改变。在这些分子中，有的基因在癌症的发生发展过程中起着一定作用，该团队预测二恶英可以改变这几个基因调控癌症发展。另外许多其他生理系统也受到二恶英影响，包括生殖系统、消化系统、血液系统以及泌尿系统等。
二恶英又称二氧杂芑，是一种无色无味、毒性严重的脂溶性物质，如除草剂或杀虫剂的制造或纸张的漂白过程中都会产生副产物二恶英。因为自然界的微生物和水解作用对二恶英的分子结构影响较小，因此，环境中的二恶英很难自然降解消除。在环境中，二恶英容易聚积在食物链中。食物链中依赖动物食品的程度越高，二恶英聚积的程度就越高。研究结果证实胎儿暴露于环境污染物二恶英下，会损害免疫系统中的microRNA表达，影响成人的免疫反应，造成终身影响。（生物谷：Bioon.com）
doi:10.1371/journal.pone.0045054
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Prenatal Exposure to TCDD Triggers Significant Modulation of microRNA Expression Profile in the Thymus That Affects Consequent Gene Expression
Narendra P. Singh, Udai P. Singh, Hongbing Guan, Prakash Nagarkatti, Mitzi Nagarkatti*
MicroRNAs (miRs) are a class of small RNAs that regulate gene expression. There are over 700 miRs encoded in the mouse genome and modulate most of the cellular pathways and functions by controlling gene expression. However, there is not much known about the pathophysiological role of miRs. TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), an environmental contaminant is well known to induce severe toxicity (acute and chronic) with long-term effects. Also, in utero exposure of fetus to TCDD has been shown to cause thymic atrophy and alterations in T cell differentiation. It is also relevant to understand “the fetal basis of adult disease” hypothesis, which proposes that prenatal exposure to certain forms of nutritional and environmental stress can cause increased susceptibility to clinical disorders later in life. In the current study, therefore, we investigated the effects of prenatal exposure to TCDD on miR profile in fetal thymocytes and searched for their possible role in causing thymic atrophy and alterations in the expression of apoptotic genes.
