利用RNA聚合酶Ⅲ依赖的启动子实现条件性RNA干扰

Conditional RNAi designed using RNA polymerase III dependent promoters

RNA干扰(RNA interference,RNAi)是指由双链RNA引发的同源mRNA特异性降解过程,目前已成为功能基因组学研究的有力工具,并广泛应用于肿瘤基因治疗研究领域。载体介导的RNAi是向细胞内引入小干扰RNA(small interference RNA)的经济、有效的方法,然而由于用来引导siRNA表达的U6、H1等RNA聚合酶Ⅲ依赖的启动子均没有可诱导性或组织特异性,所以在研究特定基因功能和在基因治疗中的应用均受到一定限制。最近研究表明使用顺式/反式转录调控元件对PolⅢ启动子进行修饰或通过Cre-LoxP系统控制PolⅢ启动子或shRNA的结构可实现可诱导性、组织特异性等条件性RNAi。这些方法的建立不仅拓宽了RNAi技术的应用范围,而且大大提高了基于RNAi技术的肿瘤基因治疗的安全性,具有良好的临床应用前景。

RNA interference is an innate cellular process of degradation of homologous mRNA induced by double-stranded RNA and is currently being considered not only as an extremely powerful tool for functional genomic analyses, but also as a potentially useful method to develop novel cancer therapeutics. Vector-based RNA interference seems to be the simple, economical and effective way to introduce small interference RNA into mammalian cells but have some limitation when being used in the field of gene therapy for that all the naive polymerase III dependent promoters like U6 or H1 promoters have no tissue-specific activity and could not be inducible. Several strategies have been developed to achieve conditional RNA interference, including modifying the transcriptional activities of polymerase III dependent promoters with cis- or trans-acting elements, controlling the structures of the polymerase III dependent promoters or small hairpin RNA by Cre recombinase. As such, the establishment of conditional RNA interference further improves the safety of RNAi-based gene therapy and makes it possible to analyze the function of certain genes that are essential to cell viability.