2012年9月18日 電 /生物谷BIOON/ --據(jù)發(fā)表在PLoS ONE雜志上的一項(xiàng)研究證實(shí),，一個(gè)眾所周知的環(huán)境污染物二惡英可以改變生理功能,。
南加州大學(xué)醫(yī)學(xué)院Narendra Singh,、Mitzi Nagarkatti和Prakash Nagarkatti研究團(tuán)隊(duì)證實(shí),，實(shí)驗(yàn)小鼠模型在懷孕期間暴露于二惡英（TCDD）下,，二惡英對(duì)胎兒可能有顯著毒性影響,，尤其是對(duì)發(fā)揮抵抗感染作用的免疫細(xì)胞毒性作用更強(qiáng),。他們發(fā)現(xiàn)二惡英會(huì)改變小分子RNA，進(jìn)而影響到大量基因的表達(dá),。
該研究分析了608個(gè)小分子RNA,，其中78個(gè)microRNAs被二惡英顯著改變。在這些分子中,，有的基因在癌癥的發(fā)生發(fā)展過程中起著一定作用,，該團(tuán)隊(duì)預(yù)測(cè)二惡英可以改變這幾個(gè)基因調(diào)控癌癥發(fā)展,。另外許多其他生理系統(tǒng)也受到二惡英影響，包括生殖系統(tǒng),、消化系統(tǒng),、血液系統(tǒng)以及泌尿系統(tǒng)等。
二惡英又稱二氧雜芑,，是一種無色無味,、毒性嚴(yán)重的脂溶性物質(zhì)，如除草劑或殺蟲劑的制造或紙張的漂白過程中都會(huì)產(chǎn)生副產(chǎn)物二惡英,。因?yàn)樽匀唤绲奈⑸锖退庾饔脤?duì)二惡英的分子結(jié)構(gòu)影響較小,，因此，環(huán)境中的二惡英很難自然降解消除,。在環(huán)境中,，二惡英容易聚積在食物鏈中。食物鏈中依賴動(dòng)物食品的程度越高,，二惡英聚積的程度就越高,。研究結(jié)果證實(shí)胎兒暴露于環(huán)境污染物二惡英下，會(huì)損害免疫系統(tǒng)中的microRNA表達(dá),，影響成人的免疫反應(yīng),，造成終身影響。（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.
