Knockdown of circRNA-Memo1 Reduces Hypoxia/Reoxygenation Injury in Human Brain Endothelial Cells Through miRNA-17-5p/SOS1 Axis.

Circ-Memo1 has been proved to be upregulated in ischemia-reperfusion induced acute injury of kidney tissues. However, the potential role of circ-Memo1 in cerebral hypoxia/reoxygenation (H/R) injury is still unclear.Blood samples were collected from 25 ischemic stroke patients and 25 healthy controls. To construct the H/R model, human brain microvascular endothelial cells (HBMVECs) were cultured under the hypoxic condition, followed by reoxygenation. Cell viability was analyzed by MTT assay. Flow cytometry was carried out to examine cell apoptosis. The level of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) were measured by MDA and SOD assay kits, respectively. The levels of TNF-α, IL-1ß, and IL-6 were determined by enzyme-linked immunosorbent assay (ELISA). Dual-luciferase reporter gene detection was employed to verify the binding relationships between circ-Memo1, miR-17-5p, and SOS1.Circ-Memo1 and SOS1 expressions were increased, and miR-17-5p expression was reduced in ischemic stroke patients. Circ-Memo1 silencing promoted cell viability, inhibited the activation of ERK/NF-κB signaling pathway, reduced oxidative stress and inflammatory response, and inhibited cell apoptosis. Moreover, miR-17-5p functioned as the sponge of circ-Memo1, and SOS1 was identified as the target of miR-17-5p. The protective effect of circ-Memo1 knockdown on cell injury after H/R treatment was weakened by miR-17-5p inhibition.Knockdown of circ-Memo1 alleviated H/R injury of HBMVEC cells by regulating the miR-17-5p/SOS1 axis, indicating that circ-Memo1 might be a potential treatment target for cerebral H/R injury.

MiR-17-5p inhibits cerebral hypoxia/reoxygenationinjury by targeting PTEN through regulation of PI3K/AKT/mTOR signaling pathway.

OBJECTIVE: To investigate the role and mechanism of miR-17-5p in cerebral hypoxia/reoxygenation (H/R)-induced apoptosis. METHODS: The present study used human brain microvascular endothelial cells (HBMVECs) to establish cerebral H/R model. MTT was used to measure the cell viability. Flow cytometry was used to detect the cell apoptosis. The interaction between miR-17-5p and PTEN was determined using dual luciferase reporter assay. RT-qPCR and Western blotting were used for determination of the expression of miR-17-5p, PTEN, apoptosis- and PI3K/AKT/mTOR signalling-related proteins. RESULTS: The cell viability and the expression of miR-17-5p were obviously down-regulated while the expression of PTEN was obviously up-regulated in H/R cells. The cell viability was remarkably enhanced, and the cell apoptosis induced by H/R injury was dramatically reduced when miR-17-5p was overexpressed in HBMVECs under H/R condition, which was reversed by overexpression of PTEN. Dual luciferase reporter assay showed PTEN was a direct target of miR-17-5p. Treatment of PI3K inhibitor LY294002 significantly increased the apoptosis rate of HBMVECs, and this effect was significantly reversed by transfection of miR-17-5p mimics, while further dramatically enhanced by overexpression of PTEN. CONCLUSION: MiR-17-5p could ameliorate cerebral I/R injury-induced cell apoptosis by directly targeting PTEN and regulation of PI3K/AKT/mTOR signalling.