SIRT1-mediated deacetylation of NF-κB inhibits the MLCK/MLC2 pathway and the expression of ET-1, thus alleviating the development of coronary artery spasm.

Coronary artery spasm (CAS) is an intense vasoconstriction of coronary arteries that causes total or subtotal vessel occlusion. The cardioprotective effect of sirtuin-1 (SIRT1) has been extensively highlighted in coronary artery diseases. The aims within this study include the investigation of the molecular mechanism by which SIRT1 alleviates CAS. SIRT1 expression was first determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis in an endothelin-1 (ET-1)-induced rat CAS model. Interaction among SIRT1, nuclear factor-kappaB (NF-κB), myosin light chain kinase/myosin light chain-2 (MLCK/MLC2), and ET-1 was analyzed using luciferase reporter assay, RT-qPCR, and Western blot analysis. After ectopic expression and depletion experiments in vascular smooth muscle cells (VSMCs), contraction and proliferation of VSMCs and expression of contraction-related proteins (α-SMA, calponin, and SM22α) were measured by collagen gel contraction, 5-ethynyl-2'-deoxyuridine (EdU) assay, RT-qPCR, and Western blot analysis. The obtained results showed that SIRT1 expression was reduced in rat CAS models. However, overexpression of SIRT1 inhibited the contraction and proliferation of VSMCs in vitro. Mechanistic investigation indicated that SIRT1 inhibited NF-κB expression through deacetylation. Moreover, NF-κB could activate the MLCK/MLC2 pathway and upregulate ET-1 expression by binding to their promoter regions, thus inducing VSMC contraction and proliferation in vitro. In vivo experimental results also revealed that SIRT1 alleviated CAS through regulation of the NF-κB/MLCK/MLC2/ET-1 signaling axis. Collectively, our data suggested that SIRT1 could mediate the deacetylation of NF-κB, disrupt the MLCK/MLC2 pathway, and inhibit the expression of ET-1 to relieve CAS, providing a theoretical basis for the prospect of CAS treatment and prevention.NEW & NOTEWORTHY Rat coronary artery spasm models exhibit reduced expression of SIRT1. Overexpression of SIRT1 inhibits contraction and proliferation of VSMCs. SIRT1 inhibits NF-κB through deacetylation to modulate VSMC contraction and proliferation. NF-κB activates the MLCK/MLC2 pathway. NF-κB upregulates ET-1 to modulate VSMC contraction and proliferation.

Downregulation of microRNA-135b promotes atherosclerotic plaque stabilization in atherosclerotic mice by upregulating erythropoietin receptor.

Atherosclerotic plaque rupture is an important pathophysiologic mechanism of acute coronary syndrome. Emerging microRNAs (miRNAs) have been implicated in the atherosclerotic plaque formation and macrophage autophagy during the development of atherosclerosis (AS). Hence, this study was conducted to explore the role microRNA-135b (miR-135b) in macrophages and atherosclerotic plaque in mouse models of AS. The expression of miR-135b and erythropoietin receptor (EPOR) was altered in atherosclerotic mice to clarify their effect on inflammation, cell activities of aortic tissues, and macrophage autophagy. The obtained findings unraveled that miR-135b was upregulated and EPOR was downregulated in atherosclerotic mice. Upregulated miR-135b expression promoted cell apoptosis and inflammation, along with inhibited cell proliferation and decreased macrophage autophagy. Notably, miR-135 was validated to target EPOR and activate the PI3K/Akt signaling pathway. Moreover, miR-135b inhibition attenuated inflammation, atherosclerotic plaque development, and promoted macrophage autophagy. Besides, the effect of miR-135b inhibition was reversed in response to EPOR silencing. Taken conjointly, the study revealed that inhibition of miR-135b promoted macrophage autophagy and atherosclerotic plaque stabilization in atherosclerotic mice by inactivating the PI3K/Akt signaling pathway and upregulating EPOR.