Xin Zhang, Jing Li, Juan-Juan Qin, Wen-Lin Cheng, Xueyong Zhu, Fu-Han Gong, Zhigang She, Zan Huang, Hao Xia, Hongliang Li

MicroRNA-145 (miR-145) has been shown to play an important role in cardiovascular system disorders; however, the underlying mechanism is not completely understood. The purpose of this study was aimed at elucidating the cardioprotective effects of miR-145 against myocardial ischemia/reperfusion (I/R) injury. We established a rat myocardial I/R model with 45 min left anterior descending coronary artery (LAD) occlusion and 2 h reperfusion. The levels of myocardial enzymes, apoptotic, inflammatory, and oxidative indices were determined. The arrhythmia score was assessed by programmed electrical stimulation (PES). Quantitative real-time PCR and western blot were applied to evaluate the expression levels of miR-145 and related target proteins, respectively. I/R injury decreased the expression of miR-145; however, upregulated miR-145 markedly reduced the elevation of ST segment, decreased corrected QT (QTc) intervals, and attenuated I/R-induced electrophysiological instability. Furthermore, miR-145 suppressed myocardium apoptotic, inflammatory, and oxidative response as well as the phosphorylation of Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), ryanodine receptor2 (RyR2 Ser2814), apoptosis signal-regulating kinase 1 (ASK1), c-Jun NH2-terminal kinases (JNK), and nuclear translocation of nuclear factor kappa-B (NF-κB) p65. In summary, overexpression of miR-145 alleviates I/R-induced myocardial electrophysiological instability and apoptotic and inflammatory response via inhibition of the CaMKII-mediated ASK1 antiapoptotic pathway and NF-κB p65 anti-inflammatory pathways.

Atherosclerosis is generally considered a chronic inflammatory response that can lead to several severe clinical cardiovascular events. MiR-150 is a small non-coding RNA that has been reported to play an important role in regulating endothelial cell proliferation and migration and intravascular environmental homeostasis. However, the exact role that miR-150 plays in atherosclerosis remains unknown. In the present study, miR-150-/-ApoE-/- mice were generated to evaluate the impact of miR-150 deficiency on atherosclerosis development. These double-knockout mice exhibited significantly decreased the sizes of atherosclerotic lesions compared with ApoE-/- mice. Additionally, these mice displayed an attenuated inflammatory response compared with their counterparts. Moreover, we observed that miR-150 ablation promoted plaque stabilization, a change characterized by increases in smooth muscle cell and collagen content and decreases in macrophage infiltration and lipid accumulation. Bone marrow transplantation and inflammatory response testing in vitro demonstrated that the role of miR-150 in atherosclerosis was largely dependent on its effects on macrophages. We noted that miR-150 deficiency directly upregulates PDLIM1 expression; however, the decreases in phosphorylated p65 expression and inflammatory cytokine secretion induced by miR-150 ablation were reversed by PDLIM1 knockdown. These findings suggest that miR-150 is a promising target for the treatment of atherosclerosis.

Background: Dickkopf‐3 ( DKK 3) is a negative regulator of the Wnt/β‐catenin signaling pathway, which is involved in inflammation. However, little is known about the relationship between DKK 3 expression and the progression of atherosclerosis. The aim of the present study was to define the role of DKK 3 and its potential mechanism in the development of atherosclerosis. Methods and Results: Immunofluorescence analysis showed that DKK 3 was strongly expressed in macrophages of atherosclerotic plaques from patients with coronary heart disease and in hyperlipidemic mice. The expression level was significantly increased in atherogenesis. DKK 3 ^−/− ApoE ^−/− mice exhibited a significant decrease in atherosclerotic lesions in the entire aorta, aortic sinus, and brachiocephalic arteries. Transplantation of bone marrow from DKK 3 ^−/− ApoE ^−/− mice into lethally irradiated ApoE ^−/− recipients resulted in a reduction of atherosclerotic lesions, compared with the lesions in recipients transplanted with ApoE ^−/− donor cells, suggesting that the effect of DKK 3 deficiency was largely mediated by bone marrow–derived cells. A reduction in the necrotic core size, accompanied by increased collagen content and smooth muscle cells and decreased accumulation of macrophages and lipids, contributed to the stability of plaques in DKK 3 ^−/− ApoE ^−/− mice. Furthermore, multiple proinflammatory cytokines exhibited marked decreases in DKK 3 ^−/− ApoE ^−/− mice. Finally, we observed that DKK 3 ablation increased β‐catenin expression in the nuclei of macrophages both in vivo and in vitro. Conclusions: DKK 3 expression in macrophages is involved in the pathogenesis of atherosclerosis through modulation of inflammation and inactivation of the Wnt/β‐catenin pathway.