Signal conduction mechanism of LncRNA H19 in promoting angiogenesis after coronary artery bypass grafting via regulating miR-22

AIM To construct a rat model of coronary artery bypass transplantation and to evaluate the signaling mechanism of LncRNA H19 in promoting angiogenesis in ischemic myocardial tissue via regulating miR-22.

METHODS Twenty SD rats were selected and randomly divided into 2 groups: observation group (treated by ligation of the anterior descending artery and the right external jugular vein-common carotid artery graft) and control group (treated with sham surgery). All rats were killed in the second week after surgery, hearts were harvested and myocardial microvascular endothelial cells (CMEC) were cultured. The expression levels of LncRNA H19 and miR-22 were measured by qRT-PCR and compared between the two groups. shRNA H19 was constructed and interfered to the expression of LncRNA H19. The miR-22 mimics and NC, and inhibitor-miR-22 and NC were transfected to CMECs induced by liposomal (Lipfectamine 2000), respectively. The invasion ability of the four CMECs groups was detected with Transwell assay, the cell proliferation ability of the five CMECs groups was detected with MTT and the tube forming capacity of CMECs was determined by Matrigel matrix.

RESULTS The expression levels of LncRNA H19 and miR-22 in the observation group were higher than those in the control group (P<0.05, P<0.01). The positive relationship of LncRNA H19 expression levels and miR-22 expression levels was confirmed (r=0.772, P<0.05). shRNA H19 could effectively interfere with the expression of miR-22 in CMECs of the observation group (P<0.05). The migration ability of CMECs by miR-22-mimics was the highest and by miR-22-inhibitor was the lowest (P<0.05), while miR-22-NC, miR-22-mimics NC and miR-22-inhibitor NC showed no difference. MTT cell proliferation test showed significant differences in OD values between the five groups (P<0.05). The OD values of CMECs by miR-22-mimics was the highest and by miR-22-inhibitor was the lowest (P<0.05), while the other 3 CMEC groups showed no difference. The tube formation ability of CMEC by miR-22-mimics was the highest and by miR-22-inhibitor was the lowest (P<0.05), while the other 3 CMEC groups showed no difference.

CONCLUSION LncRNA H19 up-regulates the expression level of miR-22 to form a signaling axis and thus promotes the new angiogenesis in rats after coronary artery bypass grafting.