MicroRNA-384-5p/Beclin-1 As Potential Indicators For Epigallocatechin Gallate Against Cardiomyocytes Ischemia Reperfusion Injury By Inhibiting Autophagy Via PI3K/Akt Pathway.

Epigallocatechin gallate (EGCG) has established protective actions against myocardial ischemia/reperfusion (I/R) injury by regulating autophagy. However, little is known about the mechanisms of EGCG in posttranscriptional regulation in the process of cardioprotection. Here we studied whether microRNAs play a role in EGCG-induced cardioprotection. The myocardial I/R injury in vitro and in vivo model were made, with or without EGCG pretreatment. The upregulation and silencing of microRNA-384-5p (miR-384) and Beclin-1 in H9c2 cell lines were established. Rats were transfected with miR-384 specific shRNA. Dual-luciferase reporter gene assay was conducted to verify the relationship between miR-384 and Beclin-1. TTC staining was performed to analyze the area of myocardial infarct size. Cell viability was monitored by cell counting kit-8 (CCK-8). The release of cardiac troponin-I (cTnI) was examined by ELISA. The levels of autophagy-related genes or proteins expression were evaluated by qRT-PCR or Western blotting. Autophagosomes of myocardial cells were detected by transmission electron microscopy and laser scanning confocal microscope. I/R increased both autophagosomes and autolysosomes, thereby increasing autophagic flux both in vitro and in vivo. Pretreatment with EGCG attenuated I/R-induced autophagic flux expression, accompanied by an increase in cell viability and a decrease in the size of myocardial infarction. MiR-384 expression was down-regulated in H9c2 cell lines when subjected to I/R, while this suppression could be reversed by EGCG pretreatment. The dual-luciferase assay verified that Beclin-1 was a target of miR-384. Both overexpression of miR-384 and knocking down of Beclin-1 significantly inhibited I/R-induced autophagy, accompanied by the activation of PI3K/Akt pathway, thus enhanced the protective effect of EGCG. However, these functions were abrogated by the PI3K inhibitor, LY294002. We confirmed that EGCG has a protective role in microRNA-384-mediated autophagy by targeting Beclin-1 via activating the PI3K/Akt signaling pathway. Our results unveiled a novel role of EGCG in myocardial protection, involving posttranscriptional regulation with miRNA-384.

Zhang C ，Liang R ，Gan X ，Yang X ，Chen L ，Jian J ... -  《Drug Design Development and Therapy》

Epigallocatechin gallate exerts protective effects against myocardial ischemia/reperfusion injury through the PI3K/Akt pathway-mediated inhibition of apoptosis and the restoration of the autophagic flux.

Xuan F ，Jian J 《-》

miR-26a-5p protects against myocardial ischemia/reperfusion injury by regulating the PTEN/PI3K/AKT signaling pathway.

Xing X ，Guo S ，Zhang G ，Liu Y ，Bi S ，Wang X ，Lu Q ... -  《-》

Berbamine postconditioning protects the heart from ischemia/reperfusion injury through modulation of autophagy.

Zheng Y ，Gu S ，Li X ，Tan J ，Liu S ，Jiang Y ，Zhang C ，Gao L ，Yang HT ... -  《Cell Death & Disease》

Exosomes of bone-marrow stromal cells inhibit cardiomyocyte apoptosis under ischemic and hypoxic conditions via miR-486-5p targeting the PTEN/PI3K/AKT signaling pathway.

Myocardial ischemia-reperfusion injury (MIRI) is a major obstacle in the treatment of ischemic heart disease. Recent studies have shown that exosomes-small membrane vesicles secreted by most cell types-could have a protective effect on the ischemic myocardium. In this study we explored the effect of exosomes derived from bone-marrow stromal cells (BMSC-exo) on cardiomyocyte apoptosis and MIRI. Exosomes were purified from culture media using the ExoQuick kit and observed using transmission electron microscopy. Cell viability was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. Cell apoptosis was analyzed by flow cytometry using the Annexin-V/PI stain. The expression levels of microRNA (miRNA), messenger RNA (mRNA) and PTEN/PI3K/AKT-pathway-related proteins were detected by qRT-PCR and western blot, respectively. Myocardial ischemia was simulated by incubating H9C2 cells in a hypoxia/reoxygenation (H/R) conditioned rat MIRI model. BMSC-exo induced the proliferation of H9C2 cells and rescued H9C2 cells from apoptosis in the H/R model, indicating that BMSC-exo has a protective effect on cardiomyocyte injury caused by H/R. Using transgenic H9C2 cells, we found that miR-486-5p in BMSC-exo suppressed the H/R-triggered apoptosis of H9C2 cells. In addition, BMSC-exo repressed the expression of PTEN in H9C2 cells via miR-486-5p, and subsequently activated the PI3K/AKT pathway in vitro. Moreover, the myocardial injury caused by ischemia/reperfusion was repaired by BMSC-exo which activates the PI3K/AKT pathway via miR-486-5p in vivo. Our results suggested that exosomes from BMSCs have a protective effect on myocardium ischemic injury. MiR-486-5p carried by BMSC-exo plays a pivotal role in the regulatory process by suppressing PTEN expression, activating the PI3K/AKT signaling pathway, and subsequently inhibiting the apoptosis of injured cardiomyocytes.

Sun XH ，Wang X ，Zhang Y ，Hui J ... -  《-》