Höckner M, Dallinger R, Stürzenbaum S R
University of Innsbruck, Institute of Zoology, Innsbruck, Austria; King's College London, Faculty of Life Sciences & Medicine, London, United Kingdom.
University of Innsbruck, Institute of Zoology, Innsbruck, Austria.
Biochem Biophys Res Commun. 2015 May 8;460(3):537-42. doi: 10.1016/j.bbrc.2015.03.065. Epub 2015 Mar 19.
In order to cope with changing environmental conditions, organisms require highly responsive stress mechanisms. Heavy metal stress is handled by metallothioneins (MTs), the regulation of which is evolutionary conserved in insects and vertebrates and involves the binding of metal transcription factor 1 (MTF-1) to metal responsive elements (MREs) positioned in the promoter of MT genes. However, in most invertebrate phyla, the transcriptional activation of MTs is different and the exact mechanism is still unknown. Interestingly, although MREs are typically present also in invertebrate MT gene promoters, MTF-1 is notably absent. Here we use Lumbricus rubellus, the red earthworm, to study the elusive mechanism of wMT-2 activation in control and Cd-exposed conditions. EMSA and DNase I footprinting approaches were used to pinpoint functional binding sites within the wMT-2 promoter region, which revealed that the cAMP responsive element (CRE) is a promising candidate which may act as a transcriptional activator of invertebrate MTs.
为了应对不断变化的环境条件，生物体需要高度灵敏的应激机制。重金属应激由金属硫蛋白（MTs）处理，其调控在昆虫和脊椎动物中具有进化保守性，涉及金属转录因子1（MTF-1）与位于MT基因启动子中的金属反应元件（MREs）结合。然而，在大多数无脊椎动物门类中，MTs的转录激活情况不同，确切机制仍不清楚。有趣的是，尽管MREs通常也存在于无脊椎动物MT基因启动子中，但明显不存在MTF-1。在这里，我们使用赤子爱胜蚓（红蚯蚓）来研究在对照和镉暴露条件下wMT-2激活的难以捉摸的机制。采用电泳迁移率变动分析（EMSA）和DNA酶I足迹法来确定wMT-2启动子区域内的功能性结合位点，结果表明环磷酸腺苷反应元件（CRE）是一个有前景的候选者，它可能作为无脊椎动物MTs的转录激活剂。
