中文摘要：

目的探究miR-342—3p是否通过作用于SM22α启动子，从转录水平调控SM22α的表达。方法通过软件RNAhybrid分析发现，大鼠SM22α启动子中存在一个miR-342—3p的识别位点。将miR-342—3pmimics与报告基因载体pGL3-SM22α-Promoter共转染293A细胞，通过检测荧光素酶活性来分析miR-342—3p对SM22α启动子转录活性的影响。将miR-342—3pmimics转染血管平滑肌细胞，采用qRT—PCR和Western blot分别检测SM220tmRNA和蛋白质水平，分析rniR-342—3p对血管平滑肌细胞中SM22α表达的影响。结果与miR—control相比，miR-342—3p能够使SM220t启动子转录活性降低（0．54±0．03）倍．差异有统计学意义（P〈0．05）；与miR—control相比，miR-342—3p能够使血管平滑肌细胞中SM22ctmRNA水平降低（0．45±0．04）倍，SM22ct蛋白质水平下降（0．41±0．05）倍，差异有统计学意义（P〈0．05）。结论miR-342—3p通过抑制SM22α启动子活性，从转录水平降低SM22α的表达．为miRNA调控血管平滑肌细胞表型转化研究提供了新角度。

英文摘要：

Objective To explore whether miR-342-3p could repress the expression of SM22α at the transcriptional level by targeting its promoter. Methods There was a potential binding site of miRT-342-3p in the SM22α promoter analyzed by using RNAhybrid software. 293A cells were co-transfected with miR-342-3p mimics and pGL3-SM22α- Promoter reporter gene vectors, luciferase activity was detected to analyze whether the SM22a promoter activity is repressed by miR-342-3p. Vascular smooth muscle cells were transfeeted with miR-342-3p mimics, SM22α mRNA and protein levels were detected by using qRT-PCR and Western blot, to explore the influence of miR-342-3p on the expression of SM22α in vascular smooth muscle cells. Results Compared with miR-eontrol, SM22a promoter transcriptional activity was reduced （0.54±0.03） folds by miR-342-3p, the difference was statistically significant （P 〈 0.05）. The SM22a mRNA in vascular smooth muscle cells was decreased （0.45±0.04） folds, and the SM22tX protein level was decreased （0.41±0.05） folds by miR-342-3p, compared with miR,eontrol, the differences were statistically significant （P 〈 0.05）. Conclusion miR-342-3p represses the expression of SM22ct at the transcriptional level by targeting its promoter, which provides a novel perspective for the study of miRNA in vascular smooth muscle cell phenotypic switch regulation.