MiR-9 promotes the phenotypic switch of vascular smooth muscle cells by targeting KLF5

Abstract

Background: Diabetic vascular smooth muscle cells (VSMCs) are characterized by increased proliferation and migration. Small non-coding microRNAs (miRNAs) have been considered critical modulators of VSMC phenotypic switch after an environmental stimulus. However, microRNA in high glucose-induced pro-inflammation and its atherogenic effect is still ambiguous. Methods: qRT-PCR was used to examine the expression of miR-9 in VSMCs. The downstream signaling protein relative to miR-9 regulation, Krüppel-like factor 5, and some marker genes of contractile VSMCs, were analyzed by western blotting and qRT-PCR. Luciferase reporter assay was used to detect the expression of KLF5, which is regulated by miR-9. To examine the function of a miR-9 inhibitor in VSMC proliferation and migration, VSMC proliferation and migration assays were performed. Results: Reduced transcriptional levels of miR-9 and expression of specific genes of contractile VSMCs were observed in the SMC cell line C-12511 treated with high glucose and SMCs, which were isolated from db/db mice. Moreover, the activity of KLF5 3′-UTR was dramatically reduced by a miR-9 mimic, and increased by a miR-9 inhibitor. The proliferation and migration of SMCs was reduced by the miR-9 mimic. Conclusion: miR-9 inhibits the proliferation and migration of SMC by targeting KLF5 in db/db mice. Keywords: miR-9; Smooth muscle cells; Proliferation; Migration; KLF5