MiR-940 regulates angiogenesis after cerebral infarction through VEGF

The aim of this study was to investigate whether miR-490 was involved in the regulation of angiogenesis after cerebral infarction by regulating vascular endothelial growth factor (VEGF) expression.

Sprague Dawley (SD) rats were used to establish a middle cerebral artery infarction model. Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was used to detect the expression levels of miR-940 in serum and brain tissues at 1, 3, and 7 days after cerebral infarction. Meanwhile, miR-940 expression in brain microvascular endothelial cells (BMECs) after Oxygen-Glucose Deprivation (OGD) for 2, 4, 6 hours was measured by qRT-PCR, respectively. The cells were transfected with miR-940 mimics/inhibitor to achieve miR-940 overexpression or inhibition. Subsequently, the angiogenesis and proliferation ability of the cells was evaluated by 5-ethynyl-2'-deoxyuridine (EDU) assay. Besides, the mRNA and protein expression levels of VEGF after miR-940 transfection were detected by Western blot and qRT-PCR, respectively. Finally, recovery experiment was used to determine whether miR-940 affected angiogenesis and proliferation of BMECs by regulating VEGF expression.

The expression level of miR-940 in serum and brain tissues of rats was markedly decreased at 1, 3, and 7 days after cerebral infarction, which was then recovered on the 7th day. After 2, 4, and 6 hours of glucose and oxygen deprivation in BMECs, the expression level of miR-940 was significantly decreased. However, it was evidently recovered after 6 hours. After miR-940 over-expression in BMECs, the angiogenesis and proliferation of BMECs were remarkably inhibited. Conversely, miR-940 inhibitor transfection could significantly promote the formation of luminal cells and the proliferation of BMECs. QRT-PCR results showed that miR-940 overexpression down-regulated the expression level of VEGF, and the same findings were observed at the protein level. Further studies revealed that VEGF could reverse the inhibitory effect of miR-940 on lumen formation and cell proliferation in BMECs.

The expression of miR-940 was downregulated in cerebral infarction. The low expression of miR-940 could promote the angiogenesis ability of cerebral microvascular endothelial cells after cerebral infarction, which might be resulted from the inhibitory effect of miR-940 on VEGF.