Abstract
Background/aimDiabetic vascular smooth muscle cells (VSMCs) are characterized by increased proliferation and migration. Small noncoding microRNAs (miRNAs) have been considered critical modulators of the VSMC phenotypic switch after an environmental stimulus. However, microRNA in high glucose-induced proinflammation and its atherogenic effect is still ambiguous. Materials and methods The technique of 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 were reduced by the miR-9 mimic. Conclusion miR-9 inhibits the proliferation and migration of SMC by targeting KLF5 in db/db mice.
Highlights
Cardiovascular disease, especially atherosclerosis that may result in mortality, is the leading complication in patients with diabetes mellitus [1]
Reduced transcriptional levels of miR-9 and expression of specific genes of contractile vascular smooth muscle cells (VSMCs) were observed in the SMC cell line C-12511 treated with high glucose and SMCs, which were isolated from db/db mice
Expression of miR-9 and KLF5 in VSMCs from db/ db mice and high glucose-induced C-12511 cells We identified the downregulation of miR-9 in diabetic VSMCs by reference to the profile of diabetes-induced miRNA [17]; based on a bioinformatic analysis, we presumed that KLF5 could be the target gene of miR-9 (Figure 1A)
Summary
Cardiovascular disease, especially atherosclerosis that may result in mortality, is the leading complication in patients with diabetes mellitus [1]. The common pathological characteristics of coronary atherosclerosis and subsequent fatal or nonfatal myocardial infarction result in the VSMCs regaining their ability to proliferate and migrate. The physiological contractile phenotype of VSMC can undergo a phenotypic change to the synthetic phenotype in response to pathological environmental stimuli, such as platelet-derived growth factors, hyperglycemia, and balloon injury. The synthetic VSMCs regained the abilities of migration and proliferation but resulted in the loss of contractility and subsequent vessel occlusion. Previous studies have shown that the proliferation and hyperglycemia-induced inflammatory responses are KLF5, a member of the family of Kruppel-like factors, belongs to a group of transcription factors containing zinc finger domains, and serves as a transcriptional activator or repressor, regulating a variety of physiological processes, including differentiation, development, and
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