β-adrenergic receptor activation promotes cardiac miR-21 expression by paracrine action of IL-6 from fibroblasts / 中国病理生理杂志

ABSTRACT

AIM:To investigate the regulation ofβ-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 10μmol/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 p GL3-21PPR 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, while24 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.