miR-92a inhibits vascular smooth muscle cell apoptosis: role of the MKK4–JNK pathway

Abstract

Vascular smooth muscle cell (VSMC) apoptosis plays an important role in vascular remodeling and atherosclerotic plaque instability. Oxidative stress in diseased vessels promotes VSMC apoptosis in part by activating the c-Jun N-terminal kinase (JNK) pathway, which has been identified as a molecular target of miR-92a in macrophages. Here, we examined the expression and biological activity of miR-92a in VSMC. Quiescent VSMC exhibited a low basal expression of miR-92a, which was positively regulated by serum stimulation and negatively regulated by H2O2. Overexpression of miR-92a decreased H2O2-induced VSMC apoptosis as indicated by TUNEL assay and cleaved caspase-3 protein levels. Using 3′UTRreporter assay, we found that miR-92a overexpression led to suppression of both mitogen-activated protein kinase kinase 4 (MKK4)- and JNK1-dependent luciferase activity. We also found that 10 mer seed match between miRNA: mRNA pair is more efficient than 8 mer seed match for us to identify authentic miRNA target. Protein levels of active phospho-JNK and phospho-c-Jun, downstream targets of the MKK4–JNK1 pathway, were also decreased by overexpressing miR-92a in VSMC under oxidative stress. Consistent with these findings, overexpression of MKK4 reversed the anti-apoptotic effects of miR-92a in oxidatively stressed VSMC. In conclusion, miR-92a overexpression inhibits H2O2-induced VSMC apoptosis by directly targeting the MKK4–JNK1 pathway.

MicroRNA-424 Protects Against Focal Cerebral Ischemia and Reperfusion Injury in Mice by Suppressing Oxidative Stress

“…MiRNAs are implicated in the cellular response to oxidative stress via several different mechanisms [24][25][26][27] ; of these, the antioxidant defense system is responsible for preventing ROS accumulation during cerebral I/R. Some miRNAs directly target antioxidant/oxidant genes; for instance, miR-34a induces apoptosis in the human glioma cell line via enhanced nicotinamide adenine dinucleotide phosphate oxidase 2 expression and ROS production, 24 whereas miR-155 modulates ROS level by targeting SH2-domain-containing inositol 5-phosphatases in macrophages.…”

“…25 Additionally, miRNAs prevent oxidative stress-induced cell apoptosis; for example, miR-214 protects cardiac myocytes against H 2 O 2 -induced injury by targeting phosphatase and tensin homolog, 26 whereas miR-92a inhibits H 2 O 2 -induced vascular smooth muscle cell apoptosis by targeting the mitogen-activated protein kinase kinase 4-cJun N-terminal kinase 1 pathway. 27 The present study investigated the effect of miR-424 on the expression and activity of the endogenous antioxidants MnSOD and EcSOD, 2 enzymes that help the brain recover from I/R injury. 28 [30][31][32][33][34] In this study, Nrf2 expression was induced by miR-424, suggesting that it is a target of miR-424 regulation; in addition, the protective function of miR-424 on neuron was inhibited by Nrf2 depletion and SOD inhibition.…”

“…МикроРНК участвуют в клеточном ответе на окси-дантный стресс посредством различных механизмов [24][25][26][27]; одним из них является система антиоксидант-ной защиты, отвечающая за предотвращение накоп-ления АФК во время церебральной И/Р. Некоторые микроРНК нацелены непосредственно на антиокси-дантные/оксидантные гены; например микроРНК-34а индуцирует апоптоз в линии клеток глиомы чело-века путем повышения экспрессии никотинамид аде ниндинуклеотидфосфатоксидазы-2 и образования АФК [24], в то время как микроРНК-155 модулирует содержание АФК посредством влияния на SH2-домен-содержащую инозитол 5-фосфатазу в макрофагах [25].…”

“…Некоторые микроРНК нацелены непосредственно на антиокси-дантные/оксидантные гены; например микроРНК-34а индуцирует апоптоз в линии клеток глиомы чело-века путем повышения экспрессии никотинамид аде ниндинуклеотидфосфатоксидазы-2 и образования АФК [24], в то время как микроРНК-155 модулирует содержание АФК посредством влияния на SH2-домен-содержащую инозитол 5-фосфатазу в макрофагах [25]. Кроме того, микроРНК предотвращает апоптоз клеток, индуцированный оксидантным стрессом; например микроРНК-214 защищает кардиомиоциты от H 2 O 2 -индуцированного повреждения посредством влияния на фосфатазу и гомолог тензина [26], в то время как микроРНК-92а ингибирует H 2 O 2 -индуцированный апоптоз гладкомышечных клеток сосудов путем воз-действия на c-Jun-N-терминальную киназу киназой митоген-активируемой протеинкиназы [27]. В настоящем исследовании изучили влияние мик-роРНК-424 на экспрессию и активность эндогенных антиоксидантов Mn-СОД и Ec-СОД, 2 ферментов, кото-рые содействуют восстановлению головного мозга после И/Р [28,29].…”

“…MiR-424 also blocked the increase in LDH leakage and MDA content caused by H 2 O 2 and improved cell viability and MnSOD activity of primary cortical neurons; these protective effects were inhibited by Nrf2 knockdown and SOD inhibitor treatment. Taken together, these results demonstrate that miR-424 reduces oxidative stress both in vivo and in vitro.MiRNAs are implicated in the cellular response to oxidative stress via several different mechanisms [24][25][26][27] ; of these, the antioxidant defense system is responsible for preventing ROS accumulation during cerebral I/R. Some miRNAs directly target antioxidant/oxidant genes; for instance, miR-34a induces apoptosis in the human glioma cell line via enhanced nicotinamide adenine dinucleotide phosphate oxidase 2 expression and ROS production, 24 whereas miR-155 modulates ROS level by targeting SH2-domain-containing inositol 5-phosphatases in macrophages.…”