Insulin ameliorates miR-1-induced injury in H9c2 cells under oxidative stress via Akt activation

Abstract

Growing evidence indicates that aberrant upregulation of microRNA-1 (miR-1) occurs in ischemic myocardium. In addition, insulin elicits metabolism-independent cardioprotection against cardiovascular diseases. The aim of this study is to determine whether insulin ameliorates miR-1-induced injury in H9c2 cells under oxidative stress and to investigate the underlying mechanisms. By quantitative real-time RT-PCR (qRT-PCR), we show that miR-1 is upregulated in H9c2 cells after treatment with hydrogen peroxide (H(2)O(2)), and this effect is both dose- and time dependent. Furthermore, expression of miR-1 decreased significantly after insulin treatment (4.5 ± 0.1 vs. 3.0 ± 0.2, p < 0.05). To determine the potential role of miR-1 in cellular injury and gene regulation, adenovirus-mediated overexpression of miR-1 was used. Overexpression of miR-1 decreased cell viability by 28 ± 2 % (n = 6, p < 0.05) and damaged Akt activation with or without H(2)O(2) treatment. To further investigate the effect of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in miR-1-induced injury, H9c2 cells were pretreated with LY294002 (10 μM LY, a specific inhibitor of PI3K) with or without insulin (100 nM) and subjected to H(2)O(2) treatment. LY pretreatment-inhibited Akt activation, lead to increased reactive oxygen species (ROS), and further decreased cell viability induced by miR-1 (n = 6, p < 0.05, n = 9-10 cells/group, p < 0.05 and n = 6, p < 0.05) under oxidative stress. This effect was abolished by insulin. In summary, our findings suggest that miR-1 expression is sensitive to H(2)O(2) stimulation. In addition, insulin decreases miR-1 expression and induces a marked protective effect on miR-1-induced injury under oxidative stress, which may be mediated by the Akt-mediated pathway. These results provide an important, novel clue as to the mechanism of the cardiovascular action of insulin.

MicroRNA-1 aggravates cardiac oxidative stress by post-transcriptional modification of the antioxidant network

“…Overexpression of miR-1 increased ROS and decreased cell viability. Insulin decreased miR-1 expression and induced a markedly protective effect on miR-1-induced injury under oxidative stress, which may be mediated by the Aktmediated pathway (Chen et al 2012).…”

Insulin improves osteogenesis of titanium implants under diabetic conditions by inhibiting reactive oxygen species overproduction via the PI3K-Akt pathway

“…It is hypothesized that the formation of ROS by activated cells modifies the TiO 2 -layer, leading to pronounced thickening of the layer and impaired biocompatibility of titanium [34]. Recent studies have reported that insulin displays anti-oxidative effects by inhibiting overproduction of O 2À and attenuating oxidative stress-mediated injury to multiple cell types, including cardiomyocytes [35], mononuclear cells [36], and neurocytes [37]. In the present study, we found that insulin treatment of osteoblasts attenuates ROS production and improves the activity of the antioxidant enzyme.…”

Acute Hyperglycemia Abolishes Ischemic Preconditioning by Inhibiting Akt Phosphorylation: Normalizing Blood Glucose before Ischemia Restores Ischemic Preconditioning

“…Akt is an important mediator of cell survival and has long been implicated in ischemic preconditioning [49]. Insulin can activate the PI3K-Akt pathway and counteract oxidative stress, likely by increasing NO release [50–52]. The mechanisms underlying hyperglycemic inhibition of Akt phosphorylation, whether direct hyperglycemic effect or indirect, were not investigated in this study.…”