MicroRNA-451a attenuates angiotensin II–induced cardiac fibrosis and inflammation by directly targeting T-box1

Hypertension or angiotensin II (Ang II) induces cardiac inflammation and fibrosis, thus contributing to cardiac remodeling. MicroRNAs (miRNAs) are considered crucial regulators of cardiac homeostasis and remodeling in response to various types of stress. It has been reported that miR-451a is involved in regulating ischemic heart injury. However, its role in Ang II-induced cardiac fibrosis remains unknown. Cardiac remodeling was induced in mice by infusion of low-dose Ang II (490 ng/kg/min) with a minipump for 2 weeks. Echocardiography and histological examinations were performed to evaluate cardiac function and pathological changes. We observed that miR-451a expression was the most significantly downregulated in the hearts of Ang II-infused mice and in both primary cardiac myocytes and fibroblasts. Overexpression of miR-451a in mice significantly attenuated Ang II–induced cardiac fibrosis and inflammation. Conversely, knockdown of miR-451a in mice aggravated this effect. Bioinformatics analysis and a luciferase reporter assay revealed that TBX1 was a direct target of miR-451a. Mechanistically, miR-451a directly targeted TBX1 expression, which inhibited TGF-β1 production in both cardiac myocytes and fibroblasts, inactivating of TGF-β1/SMAD2/3 signaling, inhibiting myofibroblast differentiation and proinflammatory cytokine expression, and leading to attenuation of cardiac fibrosis and inflammation. In conclusion, these results indicate that miR-451a acts as a novel regulator of Ang II–induced cardiac fibrosis and inflammation by directly targeting TBX1, and may be a promising therapeutic target for treating hypertensive cardiac diseases. (AU)

MicroRNA-451a attenuates angiotensin II-induced cardiac fibrosis and inflammation by directly targeting T-box1.

Hypertension or angiotensin II (Ang II) induces cardiac inflammation and fibrosis, thus contributing to cardiac remodeling. MicroRNAs (miRNAs) are considered crucial regulators of cardiac homeostasis and remodeling in response to various types of stress. It has been reported that miR-451a is involved in regulating ischemic heart injury. However, its role in Ang II-induced cardiac fibrosis remains unknown. Cardiac remodeling was induced in mice by infusion of low-dose Ang II (490 ng/kg/min) with a minipump for 2 weeks. Echocardiography and histological examinations were performed to evaluate cardiac function and pathological changes. We observed that miR-451a expression was the most significantly downregulated in the hearts of Ang II-infused mice and in both primary cardiac myocytes and fibroblasts. Overexpression of miR-451a in mice significantly attenuated Ang II-induced cardiac fibrosis and inflammation. Conversely, knockdown of miR-451a in mice aggravated this effect. Bioinformatics analysis and a luciferase reporter assay revealed that TBX1 was a direct target of miR-451a. Mechanistically, miR-451a directly targeted TBX1 expression, which inhibited TGF-ß1 production in both cardiac myocytes and fibroblasts, inactivating of TGF-ß1/SMAD2/3 signaling, inhibiting myofibroblast differentiation and proinflammatory cytokine expression, and leading to attenuation of cardiac fibrosis and inflammation. In conclusion, these results indicate that miR-451a acts as a novel regulator of Ang II-induced cardiac fibrosis and inflammation by directly targeting TBX1, and may be a promising therapeutic target for treating hypertensive cardiac diseases.

MicroRNA-27a regulates angiotensin II-induced vascular smooth muscle cell proliferation and migration by targeting α-smooth muscle-actin in vitro.

Angiotensin II (Ang II) modulates VSMCs phenotypic switch that play a critical role in the cardiovascular diseases. MicroRNA-27a (miR-27a) has been proven to be involved in regulating vascular remodeling; however, the functional role of miR-27a in VSMCs in response to Ang II stimulation need to be elucidated. Cell proliferation and migration were measured by Cell counting kit-8 (CCK-8), BrdU incorporation and scratch wound assay in VSMCs transfected with miR-27a or its inhibitor. The target of miR-27a was confirmed using bioinformatics analysis and luciferase reporter assay. Ang II treatment time-dependently increased proliferation and migration of VSMCs accompanied with downregulation of α-smooth muscle-actin (α-SMA) and upregulation of miR-27a expression. Moreover, knockdown of miR-27a in VSMCs significantly attenuated Ang II-induced cell proliferation and migration, whereas this effect was aggravated by overexpression of miR-27a. A potential mechanistic analysis revealed that miR-27a directly targeted α-SMA, which mediated miR-27a-induced cell proliferation and migration. In conclusion, these results indicate that miR-27a acts as a novel regulator of Ang II-induced proliferation and migration by directly targeting α-SMA expression in VSMCs in vitro, and may be a potential therapeutic target for treating vascular diseases.