MicroRNA-15b Deteriorates Hypoxia/Reoxygenation-Induced Cardiomyocyte Apoptosis by Downregulating Bcl-2 and MAPK3

Abstract

To investigate the role of miRNA-15b in cardiomyocyte apoptosis after ischemia reperfusion injury in acute myocardial infarction (AMI), we conducted the AMI rat model by using left anterior descending ligation and performed hypoxia/reoxygenation experiments in H9c2 cells. MiRNA-15b was measured by quantitative reverse transcription PCR (qRT-PCR). Cardiomyocyte apoptosis was determined by terminal deoxynucleotide transferase dUTP nick end labeling staining. Synthesized miRNA-15b mimic and inhibitor were transfected into H9c2 cells by Lipofectamine regent. RNA expression of B cell lymphoma/leukemia-2 (Bcl-2) and mitogen-activated protein kinase 3 (MAPK3) was examined by qRT-PCR and their protein expression was determined by western blot. Ischemia reperfusion increased miRNA-15b expression in the ischemic rat heart and resulted more severe cardiomyocytes apoptosis. In H9c2 cells, hypoxia/reoxygenation induced increased miRNA-15b expression and augmented cardiomyocyte apoptosis observed at 24 hours after 24-hour hypoxia. Compared with the vehicle group, miRNA-15b mimic further raised miRNA-15b level and increased cardiomyocyte apoptosis, whereas miRNA-15b inhibitor suppressed miRNA-15b expression and protected cardiomyocytes from apoptosis. Although the mRNA expression of the target genes Bcl-2 and MAPK3 was not changed significantly, the protein expression of these two genes were markedly reduced after miRNA-15b mimic treatment and significantly increased after transfected with miRNA-15b inhibitors. In conclusion, miRNA-15b deteriorates cardiomyocyte apoptosis by post-transcriptionally downregulating the expression of Bcl-2 and MAPK3.

RETRACTED ARTICLE: Downregulation of miR-483-5p decreases hypoxia-induced injury in human cardiomyocytes by targeting MAPK3

“…MAPK3 was demonstrated to play a protective role in apoptosis and oxidative damage [24,25]. Notably, downregulation of MAPK3 by miR-15b is associated with ameliorated cardiomyocyte injury induced by hypoxia [14]. Hao et al [13] also showed that inhibition of miR-1 promotes MAPK3 to decrease myocardial ischemiareperfusion injury in rats undergoing sevoflurane preconditioning.…”

“…MAPK3, also known as extracellular-regulated protein kinase 1 (ERK1), is reportedly upregulated after miR-1 knockdown with protective effects against myocardial ischemia-reperfusion injury in rats undergoing sevoflurane preconditioning [13]. MiR-15b was also found to reduce rat cardiomyocyte apoptosis by posttranscriptionally downregulating MAPK3 [14]. However, whether MAPK3 is a functional regulator involved in the miR-483-5p-mediated regulation of hypoxia-induced cardiomyocyte apoptosis remains unclear.…”

miR‑126‑5p regulates H9c2 cell proliferation and apoptosis under hypoxic conditions by targeting IL‑17A

“…Bcl-2 and Bax are members of the Bcl-2 family that regulate cell apoptosis by inhibiting or inducing apoptosis in a wide variety of cellular activities (29). Previous studies have reported that Bcl-2 overexpression may suppress hypoxia-induced H9c2 cell apoptosis (30,31), whereas Bax knockdown may protect H9c2 cells against hypoxia-induced apoptosis (32). Further studies reported that IL-17A inhibition increased the expression of Bcl-2 and decreased the expression of Bax (33)(34)(35).…”

Troxerutin attenuates myocardial cell apoptosis following myocardial ischemia‐reperfusion injury through inhibition of miR‐146a‐5p expression

“…Evidence has revealed that cardiac‐specific or cardiac‐enriched miRNAs have significant effects on myocardial apoptosis (Y. Liu et al, ; Zheng, Li, Kou, Yi, & Shi, ). In this study, troxerutin pretreatment inhibited the expression levels of miR‐146a‐5p as compared to the H/R group.…”