MiR-483-5p靶向增强子介导肝癌细胞IGF2和H19基因表达上调机制研究

MiRNA调控基因表达的机制非常复杂，近年来重要进展之一是在转录水平促进基因表达。我们近期研究发现，人IGF2基因内含子来源的miR-483-5p（以下简称5p）在肝癌细胞中与IGF2和H19 基因下游的增强子互补结合，上调IGF2和H19表达，但其调控机制不明确。结合既往相关研究，推测其机制不同于目前已证实的方式，可能机制为：5p招募RNA聚合酶II及CBP/p300至该增强子，激活增强子，促进增强子RNA(eRNA)转录生成，后者与中介体复合物（MC）形成eRNA-MC复合物，该复合物靶向IGF2和H19基因启动子，促进增强子-启动子染色质环形成，从而激活这两个基因表达。本研究拟通过体外细胞培养，采用免疫共沉淀、染色质免疫沉淀、染色体构象俘获等技术证明之。研究结果将有助于对5p调控基因表达机制的认识提高到一个新高度，并为肝癌靶向治疗提供新思路和靶标奠定理论基础。

The mechanism of miRNA regulating gene expression is very complex, and one of the important advances is to promote gene expression at the transcriptional level in recent years. Our recent study found that mir-483-5p (hereinafter referred to as 5p) was derived from the intron of human IGF2 gene is complementary to the enhancer downstream of IGF2 and H19 genes in liver cancer cells, and up-regulate the expression of IGF2 and H19, but the mechanism has been unclear. The previous related researchs have been proved that the mechanism was different from the way, the possible mechanism was 5p recruiting RNA polymerase II and CBP/p300 to the enhancer and promote enhancer RNA transcription (eRNA), the latter with the intermediary compounds form eRNA-MC compounds (MC), the compound targeted IGF2 and H19 gene promoter, enhancer- promoter chromatin ring formation, so as to activate the two gene expression. In this study, immunoprecipitation, chromatin immunoprecipitation and chromosomal conformational capture were used in vitro. The results of this study will help raise the understanding of the mechanism of 5p regulating gene expression to a new level, and provide new ideas and theoretical basis for the targeted treatment of liver cancer.