MicroRNA-15b promotes cardiac ischemia injury by the inhibition of Mitofusin 2/PERK pathway.

MicroRNA and mitofusin-2 (Mfn2) play an important role in the myocardial apoptosis induced by acute myocardial infarction (AMI). However, the target relationship and underlying mechanism associated with interorganelle interaction between endoplasmic reticulum (ER) and mitochondria under ischemic condition is not completely clear. MI-induced injury, Mfn2 expression, Mfn2-mediated mitochondrial function and ER stress, and target regulation by miRNA-15b (miR-15b) were evaluated by animal MI and cellular hypoxic models with advanced molecular techniques. The results confirmed that Mfn2 was down-regulated and miR-15b was up-regulated upon the target binding profile under ischemic/hypoxic condition. Our data showed that miR-15b caused cardiac apoptotic injury that was reversed by rAAV9-anti-miR-15b or AMO-15b. The damage effect of miR-15b on Mfn2 expression and mitochondrial function was observed and rescued by rAAV9-anti-miR-15b or AMO-15b. The targeted regulation of miR-15b on Mfn2 was verified by luciferase reporter and microRNA-masking. Importantly, miR-15b-mediated Mfn2 suppression activated PERK/CHOP pathway, by which leads to ER stress and mitochondrial dysfunction, and cardiac apoptosis eventually. In conclusion, our research, for the first time, revealed the missing molecular link in Mfn2 and apoptosis and elucidated that pro-apoptotic miR-15b plays crucial roles during the pathogenesis of AMI through down-regulation of Mfn2 and activation of PERK-mediated ER stress. These findings may provide an opportunity to develop new therapies for prophylaxis and treatment of ischemic heart disease.

CircNSD1 promotes cardiac fibrosis through targeting the miR-429-3p/SULF1/Wnt/ß-catenin signaling pathway.

Cardiac fibrosis is a detrimental pathological process, which constitutes the key factor for adverse cardiac structural remodeling leading to heart failure and other critical conditions. Circular RNAs (circRNAs) have emerged as important regulators of various cardiovascular diseases. It is known that several circRNAs regulate gene expression and pathological processes by binding miRNAs. In this study we investigated whether a novel circRNA, named circNSD1, and miR-429-3p formed an axis that controls cardiac fibrosis. We established a mouse model of myocardial infarction (MI) for in vivo studies and a cellular model of cardiac fibrogenesis in primary cultured mouse cardiac fibroblasts treated with TGF-ß1. We showed that miR-429-3p was markedly downregulated in the cardiac fibrosis models. Through gain- and loss-of-function studies we confirmed miR-429-3p as a negative regulator of cardiac fibrosis. In searching for the upstream regulator of miR-429-3p, we identified circNSD1 that we subsequently demonstrated as an endogenous sponge of miR-429-3p. In MI mice, knockdown of circNSD1 alleviated cardiac fibrosis. Moreover, silence of human circNSD1 suppressed the proliferation and collagen production in human cardiac fibroblasts in vitro. We revealed that circNSD1 directly bound miR-429-3p, thereby upregulating SULF1 expression and activating the Wnt/ß-catenin pathway. Collectively, circNSD1 may be a novel target for the treatment of cardiac fibrosis and associated cardiac disease.

[CircRNA-0028171 regulates arsenic trioxide-induced apoptosis in vascular endothelial cells].

The present study was aimed to investigate the effects of circRNA-0028171 on the apoptosis of vascular endothelial cells induced by arsenic trioxide (As2O3). Human umbilical vein endothelial cells (HUVECs) were treated with 0-15 µmol/L As2O3 for 24 h. Then, cellular viability was measured by MTT assay. The expression levels of circRNA-0028171, Bcl-2 and Bax mRNA were detected by real-time quantitative PCR. Bcl-2/Bax protein ratio was detected by Western blot. Whether circRNA-0028171 was involved in the regulation of HUVECs by As2O3 was investigated by transfection with overexpression plasmid of circRNA-0028171 and siRNA. The results showed that compared with the control group, As2O3 group showed decreased cellular viability, reduced Bcl-2/Bax mRNA and protein ratios, and significantly lower expression of circRNA-0028171. Overexpression of circRNA-0028171 inhibited apoptosis of HUVECs induced by As2O3. Knockdown of circRNA-0028171 by siRNA promoted As2O3-induced apoptosis in HUVECs. These results suggest that circRNA-0028171 is involved in the vascular endothelial cell apoptosis induced by As2O3.