microRNA-133b在低切应力诱导血管内皮细胞影响血管平滑肌细胞增殖中的作用

目的 研究血管内皮细胞（endothelial cells，ECs）直接感受低切应力（low shear stress，LowSS）刺激后分泌类胰岛素生长因子-1（insulin-like growth factors，IGF-1）影响血管平滑肌细胞（vascular smooth muscle cells，VSMCs）增殖这一过程中microRNAs（miRs）的作用。 方法 用平行平板流动腔系统对ECs施加1.5 Pa正常切应力（normal shear stress , NSS）和0.5 Pa低切应力（low shear stress, LowSS），Real-time PCR检测VSMCs的miRs变化。用miRs预测网站预测miR-133b靶基因并验证。Western blotting检测核糖核酸结合蛋白1 (polypyrimidine tract binding protein 1，Ptbp1) 和N-myc下游调节基因1 (N-myc downstream regulated 1，Ndrg1) 的蛋白水平变化。EdU流式检测miR-133b对VSMCs增殖的影响。 结果 IGF-1静态刺激后，VSMCs的miR-133b和miR-378a表达上升。LowSS条件下，VSMCs的miR-133b表达显著上升，miR-378a表达无明显变化。下调VSMCs的miR-133b表达，Ptbp1、Ndrg1的mRNA水平均显著升高，上调VSMCs的miR-133b的表达，Ptbp1、Ndrg1的mRNA和蛋白水平显著降低，并且显著促进VSMCs增殖。 结论 在LowSS条件下 ECs分泌IGF-1可能通过调控联合培养VSMCs的miR-133b和靶基因Ptbp1和Ndrg1促进VSMCs增殖。研究结果为心血管疾病治疗提供了一个新的潜在靶标。
Objective To investigate the role of microRNAs (miRs) in the proliferation of vascular smooth muscle cells （VSMCs）induced by endothelial insulin-like growth factor-1 (IGF-1) under low shear stress (LowSS). Methods Endothelial cells (ECs) and VSMCs were co-cultured and exposed to normal shear stress (NSS, 1.5 Pa) and LowSS (0.5 Pa) for 12 h with parallel plate flow chamber system, respectively. Real-time PCR was used to examine the expression levels of miRs. The target genes of miR-133b were predicted by multiple algorithms. The expression of polypyrimidine tract binding protein 1 (Ptbp1) and N-myc downstream regulated 1 (Ndrg1) in VSMCs was detected by Western blotting. The VSMC proliferation was detected by EdU flow cytometry assay. Results After treated with recombinant IGF-1, the expression of both miR-133b and miR-378a in VSMCs was increased. Compared with NSS, LowSS significantly induced the expression of miR-133b in the co-cultured VSMCs, but had no obvious effect on miR-378a. In VSMCs, the protein and mRNA levels of Ptbp1 and Ndrg1 were down-regulated by miR-133b mimics. miR-133b inhibitor up-regulated the mRNA levels of Ptbp1 and Ndrg1. miR-133b overexpression promoted the proliferation of VSMCs significantly. Conclusions IGF-1 secreted by ECs in response to LowSS can upregulate the expression of miR-133b in the co-cultured VSMCs, which subsequently depresses the expression of Ptbp1 and Ndrg1, and induces the proliferation of VSMCs eventually. The research findings provide a potential new target for cardiovascular disease therapy.