Molecular Epidemiology (C080), German Cancer Research Center, Im Neuenheimer Feld 581, 69120 Heidelberg, Germany.
Trends Biochem Sci. 2012 Nov;37(11):460-5. doi: 10.1016/j.tibs.2012.08.003. Epub 2012 Sep 1.
Mature miRNAs are 19-24 nucleotide noncoding RNAs that post-transcriptionally regulate gene expression in living cells by mediating targeted hydrolysis and translation inhibition of mRNAs. In recent years, miRNAs have been detected in a variety of biological fluids as extracellular nuclease-resistant entities. Importantly, extracellular circulating miRNAs are aberrantly expressed in blood plasma or serum during the course of many diseases, including cancer, and are promising noninvasive biomarkers. However, the biological function of extracellular miRNAs remains questionable. In this article, we summarise the current theories regarding extracellular miRNA origin and function, and suggest that these miRNAs are mostly byproducts of cellular activity. Nevertheless, some extracellular miRNA species might also carry cell-cell signaling function.
成熟的 miRNA 是 19-24 个核苷酸的非编码 RNA，通过介导靶向水解和翻译抑制 mRNAs，在后转录水平上调节活细胞中的基因表达。近年来，miRNA 已被检测到在多种生物体液中作为细胞外核酸酶抗性实体存在。重要的是，在许多疾病（包括癌症）过程中，血浆或血清中的循环外泌体 miRNA 表达异常，是有前途的非侵入性生物标志物。然而，细胞外 miRNA 的生物学功能仍然存在疑问。在本文中，我们总结了关于细胞外 miRNA 起源和功能的现有理论，并提出这些 miRNA 主要是细胞活动的副产物。然而，一些细胞外 miRNA 物种也可能具有细胞间信号传递功能。
