Angiotensin II Downregulates MicroRNA-145 to Regulate Kruppel-like Factor 4 and Myocardin Expression in Human Coronary Arterial Smooth Muscle Cells under High Glucose Conditions

Abstract

MicroRNA (miR)-145 is the most abundant miR in vascular smooth muscle cells (VSMCs). However, the effect of hyperglycemia on the regulation of miR-145 is unknown. We hypothesized that the hyperglycemic condition activates a proinflammatory response that mediates the expression of miR-145 in VSMCs. We investigated whether miR-145 serves as a critical regulator to regulate the downstream proliferation factors (including Kruppel-like factor 4 [Klf4] and myocardin) in VSMCs under hyperglycemic conditions. Human coronary artery smooth muscle cells (HCASMCs) were cultured under high glucose conditions. Sustained high glucose at 25 mmol/L significantly decreased the expression of miR-145 in HCASMCs. High glucose significantly increased angiotensin II (Ang II) secretion from HCASMCs and Ang II suppressed miR-145 expression in HCASMCs. Ang II repression of miR145 expression resulted in increased Klf4 and decreased myocardin expression under conditions of high glucose. Overexpression of miR-145 significantly decreased Klf4 and increased myocardin expression and inhibited HCASMC proliferation and migration induced by a high glucose state. Balloon injury of the carotid artery in diabetic rats was performed to investigate miR-145, Klf and myocardin expression. The expression of miR-145 was maximally increased at 7 d after carotid injury and gradually declined thereafter. Overexpression of miR-145 and treatment with valsartan reversed Klf4 and myocardin protein expression induced by balloon injury and improved vascular injury. In conclusion, our study reveals that Ang II downregulates miR-145 to regulate Klf4 and myocardin expression in HCASMCs under high glucose conditions. Ang II plays a critical role in the regulation of miR-145 under hyperglycemic conditions.

MicroRNA‐145 regulates disabled‐2 and Wnt3a expression in cardiomyocytes under hyperglycaemia

“…We have previously proved that miR-145 expression was not caused by the osmotic effect of high glucose concentration. 19 As shown in Figure 1B, 25 mmol/L high glucose concentration increased miR-145 expression maximally at 0.5 hour and decreased gradually and reached significantly less than the control level after 4 to 6 hour.…”

“…An 88 bp miR‐145 precursor construct was generated as previously described . Antagomir‐145 and mutant‐miR‐145 precursor construct was generated in pmR‐ZsGreen1 plasmid vector.…”

“…An 88 bp miR-145 precursor construct was generated as previously described. 19 Antagomir-145 and mutant-miR-145 precursor construct was generated in pmR-ZsGreen1 plasmid vector. The mutant-miR-145 precursor sequence was mutated from GTCCAG of the miR-145 precursor construct to CTGGAC.…”

Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

“…ANG II also decreases miR-145-mediated suppression of Kruppellike factor 4 (KLF4) in VSMCs. Increased KLF4 reduces myocardin expression thereby increasing VSMC proliferation and migration (962).…”

Extrinsic and Intrinsic Regulation of Axon Regeneration by MicroRNAs after Spinal Cord Injury

“…STAT3 and KLFs can be regulated by miR-185, miR-19b, let-7, miR-22, miR-203, miR-93, miR-10b, miR-337, miR-145, and so on [99–103], and some of these microRNAs are dysregulated after SCI (Table 1). In contrast, KLF4 can directly upregulate miR-203 to promote cell senescence [104].…”