生物谷：研究人员在8月在线出版的《自然—方法学》上报告，通过基因工程合成的一种抑制剂能够吞食哺乳类动物细胞中的小分子RNA。抑制小分子RNA的活性有助于深入认识它们在正常发育和疾病中的功能。
与更长的信使RNA不一样，小分子RNA没有含有制造蛋白质的信息，它只拥有21个核苷酸，但这种序列却能调控信使RNA的表达。小分子RNA的序列与其目标物——信使RNA的序列部分相连，结果令信使RNA的或是分解或是蛋白质转录的过程被中止。科学家们早已将某种小分子RNA的过度表达与癌症和其他疾病联系起来，因此，深入认识这些小分子RNA的功能非常重要。
Philip Sharp和同事研制出一种可目标阻断小分子RNA的特殊工具，这个工具的基本原理是：用一种补充的假序列来吞食全部的小分子RNA，让信使RNA不受阻挡地表达出蛋白质。与以前描述的化学合成小分子RNA抑制剂的方法相反，这些吞食小分子RNA的“海绵”是通过基因工程编码的，它们提供给细胞的信息或者是形成一种质粒，或者是被整合进某个细胞的序列。新工作提供了在一个更高水平上控制细胞中小分子RNA水平的方法，让研究人员能够在特定细胞或组织中研究小分子RNA的功能。（科学时报）
原始出处:
Published online: 12 August 2007; | doi:10.1038/nmeth1079
MicroRNA sponges: competitive inhibitors of small RNAs in mammalian cells
Margaret S Ebert, Joel R Neilson & Phillip A Sharp
Center for Cancer Research, E17-529B Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Correspondence should be addressed to Phillip A Sharp sharppa@mit.edu
MicroRNAs are predicted to regulate thousands of mammalian genes, but relatively few targets have been experimentally validated and few microRNA loss-of-function phenotypes have been assigned. As an alternative to chemically modified antisense oligonucleotides, we developed microRNA inhibitors that can be expressed in cells, as RNAs produced from transgenes. Termed 'microRNA sponges', these competitive inhibitors are transcripts expressed from strong promoters, containing multiple, tandem binding sites to a microRNA of interest. When vectors encoding these sponges are transiently transfected into cultured cells, sponges derepress microRNA targets at least as strongly as chemically modified antisense oligonucleotides. They specifically inhibit microRNAs with a complementary heptameric seed, such that a single sponge can be used to block an entire microRNA seed family. RNA polymerase II promoter (Pol II)-driven sponges contain a fluorescence reporter gene for identification and sorting of sponge-treated cells. We envision the use of stably expressed sponges in animal models of disease and development.
