β-肾上腺素受体介导成纤维细胞旁分泌IL-6促进心脏miR-21表达

β-adrenergic receptor activation promotes cardiac miR-21 expression by paracrine action of IL-6 from fibroblasts

目的:探讨β-肾上腺素受体(β-adrenergic receptor,β-AR)激动剂异丙基肾上腺素(isoproterenol,ISO)促进心脏微小RNA-21(miR-21)表达的调控机制。方法:采用酶消化法分离原代乳小鼠心肌细胞和心脏成纤维细胞,分别给予ISO(10μmol/L)处理1、6、12、24和48 h,采用real-time PCR法检测细胞miR-21表达水平,采用Western blot法检测细胞p-STAT3和STAT3的蛋白水平,采用ELISA法检测细胞上清中白细胞介素6 (IL-6)的浓度。给予细胞转染含miR-21启动子区萤光素酶报告基因质粒p GL3-21PPR,采用萤光素酶报告基因实验检测条件培养液对miR-21的转录活性的影响。结果:以ISO作用于心脏成纤维细胞产生的培养液上清作为条件培养液,其可使心肌细胞miR-21的表达量随ISO作用于成纤维细胞时间的延长而逐渐增高(P <0.05);该条件培养液可引起心肌细胞miR-21的转录活性显著增加,其中ISO作用24 h和48 h的培养液分别使其转录活性增加94.9%和77.1%(P <0.01);ISO作用成纤维细胞形成的条件培养液中IL-6浓度显著增加,通过旁分泌作用于心肌细胞,引起转录因子STAT3活性增强,促进了miR-21的转录和表达。结论:激动β-AR可介导成纤维细胞合成和表达IL-6,旁分泌作用于心肌细胞,通过IL-6/STAT3途径,上调心脏miR-21表达水平,参与心脏重构。

AIM:To investigate the regulation of β-adrenergic receptor(β-AR)agonist isoproterenol(ISO)on cardiac microRNA-21(miR-21)expression.METHODS:The primary cultured mouse cardiomyocytes and cardiac fibroblasts were isolated by enzyme digestion and treated with ISO at 10 μmol/L for 1,6,12,24 and 48 h.The expression of miR-21 was detected by real-time PCR.The protein levels of p-STAT3 and STAT3 were determined by Western blot,and the concentration of interleukin-6(IL-6)in the cultured supernatant was measured by ELISA.The cells were transfected with the luciferase reporter gene plasmid pGL3-21PPR containing the miR-21 promoter region,and the luciferase reporter gene assay was used to examine the effect of conditioned medium on the transcriptional activity of miR-21.RESULTS:The medium supernatant produced by ISO on cardiac fibroblasts was used as the conditioned medium,which increased the miR-21 expression in the cardiomyocytes in a time-dependent manner after fibroblasts was treated with ISO(P<0.05).The conditioned medium caused a significant increase in the transcriptional activity of miR-21 in the cardiomyocytes,while 24 h and 48 h conditioned medium increased the transcriptional activity by 94.9% and 77.1%,respectively(P<0.01).The concentration of IL-6 in the conditioned medium was significantly increased,and the activity of transcriptional factor STAT3 was enhanced by paracrine action of IL-6 in the cardiomyocytes,which promoted the transcription and expression of miR-21.CONCLUSION:β-AR stimulation induces fibroblast synthesis and expression of IL-6 with paracrine effect on cardiomyocytes,up-regulates the expression of miR-21 in cardiomyocytes by IL-6/STAT3 pathway,and participates in the cardiac remodeling.