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Hypoxia-induced deregulation of miR-126 and its regulative effect on VEGF and MMP-9 expression.

ABSTRACT: OBJECTIVE: miR-126, the miRNA considered to be specially expressed in endothelial cells and hematopoietic progenitor cells, is strongly associated with angiogenesis. The purpose is to evaluate the role of miR-126 in hypoxia-induced angiogenesis and the possible mechanisms. METHODS: The expression of miR-126 was detected in hypoxia-treated RF/6A cells and diabetic retinas using real-time PCR. The miR-126 was up- or down-regulated by transfecting miR-126-mimics or inhibitors into RF/6A cells. Cell cycle analysis was performed using flow cytometry. The protein levels of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) were assessed by immunoblotting. RESULTS: A significantly decreased expression of miR-126 was found in hypoxia-treated RF/6A cells in a time-dependent manner compared with normoxic condition. The expression of miR-126 was also reduced in the retina tissue of streptozotocin-induced diabetic rats. The expression of VEGF and MMP-9 proteins was increased in hypoxia-induced RF/6A cells. In the functional analysis, miR-126-mimic significantly reduced the percentage of RF/6A cells in S phases compared with the negative control under hypoxic conditions. Furthermore, the VEGF and MMP-9 protein levels were sharply decreased in hypoxia-induced RF/6A cells pretreated with miR-126-mimics and increased in the cells pretreated with miR-126-inhibitors. CONCLUSIONS: miR-126 is down-regulated under hypoxic condition both in vitro and in vivo and may halt the hypoxia-induce neovascularization by suspending the cell cycle progression and inhibiting the expression of VEGF and MMP-9.

SUBMITTER: Ye P

PROVIDER: S-EPMC3880987 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background Few reports have addressed the mechanism by which microRNA miR-10b-5p regulates post-myocardial infarction (post-MI) cardiomyocyte apoptosis under hypoxic conditions. Methods and Results C57BL/6 mice underwent surgical ligation of the left anterior descending artery to create an MI or ischemia/reperfusion animal model. The expression of miR-10b-5p, PTEN (phosphatase and tensin homolog), and HIF-1? (hypoxia-inducible factor 1?) was detected in infarct border zone tissues at various time points. After precordial injections of the negative control or miR-10b-5p, overexpression lentiviruses were made in the areas surrounding the MI sites at 1 week, and myocardial infarct size, cardiac function, and cardiomyocyte apoptosis were examined. A miR-10b-5p mimic was transfected into primary mouse cardiomyocytes to analyze its effects on cardiomyocyte apoptosis and PTEN expression. Meanwhile, PTEN as a target of miR-10b-5p was verified via luciferase reporter gene assays. Cotransfection of miR-10b-5 and PTEN verified the relationship between miR-10b-5 and PTEN. Under hypoxic stress, the expression of HIF-1? and miR-10b-5p was examined. The results showed that miR-10b-5p expression was markedly reduced in the infarct border zone. Overexpression of miR-10b-5p in the murine model of MI significantly reduced MI size, improved cardiac function, and inhibited apoptosis. Overexpression of miR-10b-5p in vitro antagonized hypoxia-induced cardiomyocyte apoptosis and specifically inhibited the expression of the apoptosis-related gene PTEN, but overexpression of PTEN weakened these effects. We also found that hypoxia-induced accumulation of HIF-1? resulted in decreased expression of miR-10b-5p. Interfering with the activation of the HIF-1? signaling pathway promoted Pri-miR-10b and miR-10b-5p expression and inhibited PTEN expression. Conclusions MicroRNA miR-10b-5p antagonizes hypoxia-induced cardiomyocyte apoptosis, indicating that miR-10b-5p may serve as a potential future clinical target for the treatment of MI.

Project description:The present study aimed to investigate the significant role of ?-elemene in mouse models of oxygen-induced retinopathy (OIR). C57BL/6J neonatal mice were used to establish OIR models. They were divided into four groups: Normoxia, OIR, OIR control and OIR?treated. Mice in the OIR group were exposed to 75±5% oxygen for 5 days and returned to a normal oxygen environment on postnatal day 12 (P12). The OIR treated group was intravitreally injected with 1 µl ??elemene on P12 and subsequently returned to a normal oxygen environment for 5 days (P12?P17). Retinas were obtained on P17. Retinal neovascularization (RNV) was detected using adenosine diphosphatase staining and analyzed by counting the nuclei of neovascular endothelial cells. Vascular endothelial growth factor (VEGF) expression was determined by reverse transcription?quantitative polymerase chain reaction, immunohistochemistry and western blot analysis. MicroRNA (miRNA/miR) microarrays were used to screen out differentially expressed miRNAs between the OIR and ??elemene?treated groups. Binding the 3'?untranslated region (UTR) of VEGF and miR?27a was confirmed using luciferase assays. It was found that high oxygen concentrations accelerated RNV and increased the number of preretinal neovascular cells; ??elemene treatment reduced these effects. VEGF mRNA and protein expression was higher in the OIR and OIR control groups, compared with the normoxia and OIR?treated groups. Further, it was shown that miR?22, miR?181a?1, miR?335?5p, miR?669n, miR?190b, miR?27a and miR?93 were upregulated in the OIR?treated group, and downregulated in the OIR group. The prediction websites TargetScan and miRanda revealed that VEGF contained a potential miR?27a binding site in its 3'?untranslated region (UTR). Luciferase assays demonstrated that miR?27a directly bound to the 3'?UTR of VEGF. In vitro experiments demonstrated that miR?27a inhibited VEGF expression. In addition, ??elemene treatment upregulate miR?27a expression in vivo and in vitro. When miR?27a expression was depleted by miR?27a inhibitor, the protective effect of ??elemene on RNV was eliminated. The present study demonstrated that ??elemene reduced RNV in mouse OIR models via miR?27a upregulation, leading to reduced VEGF expression. This finding may contribute to the development of novel therapeutic strategies for human retinopathy.

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Hypoxia-induced deregulation of miR-126 and its regulative effect on VEGF and MMP-9 expression.

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