The study was employed to probe long non-coding RNA X-inactive specific transcript RNA (lncRNA XIST) expression profile and its influence on cell cycle, proliferation and apoptosis in myocardial cells. We also aimed to explore the possible meditating relationship between XIST, PDE4D and miR-130a-3p. Gene differential analysis was carried out using Human LncRNA Microarray V3.0. Quantitative real-time PCR (qRT-PCR) was used to test mRNA expressions of XIST, miR-130a-3p and PDE4D in normal cells and post-myocardial infarction (MI) cells. Western blot was applied to determine the protein expression profile of PED4D. Changes in viability and cell cycle/apoptosis of post-MI myocardial cells after silencing of XIST or PDE4D were investigated by MTT assay and flow cytometry, respectively. The targeting relationship between miR-130a-3p and XIST, PDE4D in myocardial cells were verified by dual luciferase reporter assay. Simulated MI environment was constructed by performing anoxic preconditioning in normal cells to probe the influence of XIST on myocardial cell apoptosis. XIST and PDE4D were overexpressed in post-MI myocardial cells, while miR-130a-3p was underexpressed in post-MI myocardial cells. High-expressed XIST and PDE4D both promoted myocardial cell apoptosis. High-expressed XIST also inhibited myocardial cell proliferation. XIST down-regulated miR-130a-3p and PDE4D was a direct target of miR-130a-3p. LncRNA XIST promotes MI by targeting miR-130a-3p. MI induced by PDE4D can be reversed by miR-130a-3p. This article is protected by copyright. All rights reserved.

Background/Aims: In recent years, microRNA-495 (miR-495) has been reported to be a tumor-suppressor miR that is down-modulated in cancers. However, its potential mechanism remains unknown. Therefore, this study aimed to demonstrate the role of miR-495 in cardiac microvascular endothelial cell (CMEC) injury and inflammatory reaction by mediating the pyrin domain-containing 3 (NLRP3) inflammasome signaling pathway. Methods: Overall, 40 mice were assigned into myocardial ischemia/reperfusion injury (MIR) and sham groups. After model establishment, the levels of troponin T (TnT), troponin I (TnI), N-terminal pro-B-type natriuretic peptide (NT-proBNP), creatine kinase isoenzyme MB (CK-MB), myoglobin (MYO), tumor necrosis factor-alpha (TNF-α), and interleukin 1beta (IL-1β) were detected by Enzyme-Linked Immunosorbent Assay (ELISA). Apoptosis was evaluated using Terminal deoxy (d)-UTP nick end labeling (TUNEL) staining, the level of NLRP3 protein was determined by immunohistochemical assay, and miR-495 was detected by in situ hybridization (ISH). The infarct size was determined using 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. The expression of miR-495 and the mRNA and protein levels of NLRP3, TNF-α, IL-1β, IL-18 and caspase-1 were evaluated by RT-qPCR and western blot analysis. After transfection, the cells were treated with a miR-495 mimic, a miR-495 inhibitor, or siNLRP3. Cell proliferation was measured by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and cell cycle and apoptosis by flow cytometry. Results: Mice with myocardial I/R injury had elevated levels of TnT, TnI, NT-proBNP, CK-MB, MYO, TNF-α and IL-1β; enhanced cell apoptosis; increased expression of NLRP3, TNF-α, IL-1β, IL-18 and caspase-1; and decreased miR-495 expression. MiR-495 was confirmed to target NLRP3. Moreover, miR-495 reduced the mRNA and protein levels of NLRP3, TNF-α, IL-1β, IL-18 and caspase-1, inhibited cell apoptosis and decreased cells at the G₀/G₁ phase while improving cell proliferation and increasing cells at the S phase. However, the effects of NLRP4 were proved to be reciprocal. Conclusion: In conclusion, the current study indicated that miR-495 improved CMEC injury and inflammation by suppressing the NLRP3 inflammasome signaling pathway.

Coronary heart disease (CHD) is one of the leading causes of heart-associated deaths worldwide. This study aimed to investigate the mechanism by which microRNA-363-3p (miR-363-3p) regulates endothelial injury induced by inflammatory responses in CHD. The expression patterns of miR-363-3p, NADPH oxidase 4 (NOX4), and p38 MAPK/p-p38 MAPK were examined in an established atherosclerosis (AS) model in C57BL/6 mice and in isolated coronary arterial endothelial cells (CAECs) after gain- or loss-of-function experiments. We also measured the levels of inflammatory factors (IL-6, ICAM-1, IL-10 and IL-1β), hydrogen peroxide (H 2 O 2 ), and catalase (CAT) activity, followed by detection of cell viability and apoptosis. In AS, miR-363-3p was downregulated and NOX4 was upregulated, while miR-363-3p was identified as targeting NOX4 and negatively regulating its expression. The AS progression was reduced in NOX4 knockout mice. Furthermore, miR-363-3p resulted in a decreased inflammatory response, oxidative stress, and cell apoptosis in CAECs while augmenting their viability via blockade of the p38 MAPK signaling pathway. Overall, miR-363-3p hampers the NOX4-dependent p38 MAPK axis to attenuate apoptosis, oxidative stress injury, and the inflammatory reaction in CAECs, thus protecting CAECs against CHD. This finding suggests the miR-363-3p-dependent NOX4 p38 MAPK axis as a promising therapeutic target for CHD.

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