miR-552-3p modulates transcriptional activities of FXR and LXR to meliorate hepatic glycolipid metabolism disorder

According to our previous discovery that miR-552-3p could regulate the gene expression both in cytoplasm and nucleus. Furthermore, we found the sequence in miR-552-3p was similar with cis-elements of NR1 subfamily, the important regulator of glycolipid metabolism, suggesting miR-552-3p may play a pivotal role in metabolism. To find the genes regulated by miR-5523-p, RNA-seq was used and the difference expression genes in HepG2 cells transfected with miR-552-3p or negative control was detected. Meanwhile, to found which genes are regulated by cytoplasmic miR-552-3p or nuclear miR-552-3p, importin8 expression was silenced by siRNA in the HepG2 cell and the effect of miR-552-3p on the genes expression was detected. The results of this study are showed the genes regulated by miR-552-3p and distinguish which genes are regulated by the cytoplasmic miR-552-3p or nuclear miR-552-3p. The HepG2 cells was transfected with miR-552-3p mimics(1nM) or negative control(1nM), under condition with importin8 siRNA(30nM) or negative control(30nM). After 72h, the cell was lysed by trizol and the total RNA was extracted.Each group was given two experiments.

基于我们前期的研究发现，miR-552-3p可在细胞质与细胞核内调控基因表达。进一步研究发现，miR-552-3p的序列与糖脂代谢重要调控因子NR1亚家族的顺式作用元件具有相似性，提示miR-552-3p可能在代谢过程中发挥关键调控作用。

为筛选受miR-552-3p调控的靶基因，本研究采用RNA测序（RNA-seq）技术，检测了转染miR-552-3p模拟物或阴性对照的HepG2细胞中的差异表达基因。同时，为明确受细胞质miR-552-3p或细胞核miR-552-3p调控的靶基因，我们通过小干扰RNA（siRNA）沉默HepG2细胞中的importin8基因表达，并检测miR-552-3p对基因表达的调控效应。

本研究结果明确了受miR-552-3p调控的靶基因，并区分了分别受细胞质miR-552-3p与细胞核miR-552-3p调控的靶基因。

实验设置四组处理：分别转染1nM miR-552-3p模拟物、1nM阴性对照，或联合转染30nM importin8 siRNA、30nM阴性对照。转染72小时后，采用Trizol试剂裂解细胞并提取总RNA。每组设置2次重复实验。