The present study aimed to investigate the roles of miR-132 in myocardial ischaemia/reperfusion (I/R) injury and the underlying mechanisms. The myocardial I/R model was established using c57BL/J6 mice. Haematoxylin and eosin staining was performed to observe the injury of myocardial tissues. commercial kits were used to measure the levels of serum myocardial enzymes and inflammatory factors. The in vitro I/R model was established by the hypoxia/reoxygenation method using H9c2 cells. A dual luciferase reporter assay was used to confirm the binding of miR-132 and sirtuin 1 (SIRT1). Cell pyroptosis was determined using flow cytometry. Reverse transcription-quantitative PcR was performed to determine the expression of miR-132, SIRT1 and inflammatory factors. The levels of peroxisome proliferator-activated receptor gamma coactivator (PGc)-1α/nuclear factor erythroid-2-related factor 2 (Nrf2) signalling, oxidative stress and pyroptosis-related proteins were detected by western blotting. Apparent histologic injury and elevated levels of serum myocardial enzymes and inflammatory factors were observed in the myocardial I/R model. miR-132 was significantly upregulated and SIRT1 was markedly downregulated in I/R myocardial tissues. miR-132 directly targeted SIRT1 and negatively regulated the expression of SIRT1. PGc-1α, Nrf2, endothelial nitric oxide synthase and superoxide dismutase levels were significantly decreased, while inducible nitric oxide synthase and malondialdehyde levels were significantly increased by I/R induction. The pyroptosis-related proteins NLRP3, caspase-1 and interleukin (IL)-1β were also significantly elevated by I/R induction. Inhibition of miR-132 activated PGc-1α/Nrf2 signalling and inhibited oxidative stress and the expression of the pyroptosis-related proteins NLRP3, caspase-1 and IL-1β, which were all reversed by inhibiting SIRT1 with EX527. The findings of the present study indicated that inhibition of miR-132 may ameliorate myocardial I/R injury by inhibiting oxidative stress and pyroptosis through activation of PGc-1α/Nrf2 signalling by targeting SIRT1.
Ischemia/reperfusion (I/R) injury is an inevitable process during heart transplant and suppressing I/R injury could greatly improve the survival rate of recipients. Mesenchymal stem cells (MSCs) have positive effects on I/R. We aimed to investigate the mechanisms underlying the protective roles of MSCs in I/R. Both cell model and rat model of myocardial I/R were used. MTT assay and flow cytometry were used to measure cell viability and apoptosis, respectively. QRT-PCR and western blotting were employed to measure levels of lncRNA HCP5 (HLA complex P5), miR-497, apoptosis-related proteins, and insulin-like growth factor (IGF1)/PI3K/AKT pathway. Dual luciferase assay was used to validate interactions of HCP5 and miR-497, miR-497 and IGF1. Echocardiography was performed to evaluate cardiac function of rats. Serum levels of CK-MB and LDH were measured. H&E and Masson staining were used to examine morphology of myocardial tissues. hBMSC-derived exosomes (hBMSC-Exos) increased the viability of cardiomyocytes following hypoxia/reperfusion (H/R) and decreased apoptosis. H/R diminished HCP5 expression in cardiomyocytes while hBMSC-Exos recovered the level. Overexpression of HCP5 in hBMSC-Exos further enhanced the protective effects in H/R while HCP5 knockdown suppressed. HCP5 directly bound miR-497 and miR-497 targeted IGF1. miR-497 mimics or si-IGF1 blocked the effects of HCP5 overexpression. Further, hBMSC-Exos alleviated I/R injury in vivo and knockdown of HCP5 in hBMSC-Exos decreased the beneficial effects. AntagomiR-497 blocked the effects of HCP5 knockdown. HCP5 from hBMSC-Exos protects cardiomyocytes against I/R injury via sponging miR-497 to disinhibit IGF1/PI3K/AKT pathway. These results shed light on mechanisms underlying the protective role of hBMSC-Exos in I/R.
Luteolin is a falconoid compound, which exhibits anticancer properties, however, its contribution to Sirt1-mediated apoptosis in human non-small cell lung cancer remains to be elucidated. The present study confirmed that the anticancer effect of luteolin on NCI-H460 cells was through Sirt1-mediated apoptosis. The NCI-H460 cells were treated with different concentrations of luteolin, and a 3-(4,5-dimeth yl-2-thiazolyl)-2,5-diphnyl-2H-tetrazolium bromide assay, cell cycle analysis and annexin-V/fluorescein isothiocyanate and propidium double staining were performed to assess the apoptotic effect of luteolin. Wound healing and Transwell assays were performed to confirm the inhibition of NCI-H460 cell migration. The protein levels of Sirt1 were knocked down in the NCI-H460 cells using a lentivirus to further investigate the role of this protein, and the expression levels of the apoptotic associated proteins, Bad, Bcl-2, Bax, caspase-3 and Sirt1, were measured using western blotting. The results of the present study demonstrated that luteolin exerted an anticancer effect against NCI-H460 cells through Sirt1-mediated apoptosis and the inhibition of cell migration.
Cardiac hypertrophy can cause heart failure. However, the mechanisms underlying the progression of cardiac hypertrophy remain unclear. Emerging evidence suggests that circular RNAs (circRNAs) play a critical role in cardiac hypertrophy. However, the association between circ_nuclear factor I X (circNfix) and cardiac hypertrophy remain largely unknown. Therefore, the aim of the present study was to explore the role of circNfix in cardiac hypertrophy. In order to detect the function of circNfix in cardiac hypertrophy, cardiomyocytes were stimulated with angiotensin II (Ang II) to mimic the pathogenesis of the disease. In addition, pressure overload-induced cardiac hypertrophy in a mouse model was established using transverse aortic constriction (TAC) surgery. The mechanism via which circNfix regulated cardiac hypertrophy was investigated using RNA pulldown and luciferase reporter assays, and fluorescence in situ hybridization (FISH). circNfix was downregulated in Ang II-treated cardiomyocytes. Similarly, circNfix expression was markedly downregulated in mice following TAC surgery. In addition, circNfix overexpression significantly prevented the progression of cardiac hypertrophy in TAC-treated mice. Luciferase activity and RNA pull-down assays indicated that circNfix could indirectly target activating transcription factor 3 (ATF3) by binding with microRNA (miR)-145-5p in cardiomyocytes. miR-145-5p overexpression or ATF3 knockdown could reverse the effects of circNfix in Ang II-treated mouse cardiomyocytes. circNfix attenuated pressure overload-induced cardiac hypertrophy by regulating the miR-145-5p/ ATF3 axis. Therefore, circNfix may serve as a molecular target for cardiac hypertrophy treatment.
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