LncRNA MALAT1 improves cerebral ischemia-reperfusion injury and cognitive dysfunction by regulating miR-142-3p/SIRT1 axis

Purpose:To investigate the regulation and related mechanisms of MALAT1 in cerebral ischemia- reperfusion (CI/R) injury.Materials and methods:72 mice were divided into sham group (n=24), MCAO group (n=24), MCAO+pcDNA-NC group (n=12) and MCAO+MALAT1 group (n=12). At 12 h, 24 h and 48 h after reperfusion, 6 mice were randomly selected from the sham group and the MCAO group to detect the expression of MALAT1, miR-142-3p and SIRT1 in brain tissue. All mice were scored for neurobehavioral after 48 h of reperfusion. After the completion of the scoring, 6 mice were randomly selected from each group and brain tissue was obtained for TTC analysis. The remaining mice of each group were kept on the Morris water maze test after 3 days of feeding. TTC staining and cerebral infarct volume determination. The infarct size of each brain slice was calculated using Image J image analysis software. OGD/R model PC12 cells were prepared according to simulating CI/R injury in vitro. MALAT1 was cloned into the pcDNA3.1 to construct a MALAT1 overexpression vector with the empty vector NC as a control. Plasmid or oligonuceotides were transfected into PC12 cells. The content of TNF-alpha, IL-1 beta, IL-6, the content of reactive oxygen species (ROS), malondialdehyde (MDA) in brain tissue was detected. The activity of superoxide dismutase (SOD), catalase (CAT) activity was measured.Results:MALAT1 was down-regulated in a time-dependent manner in CI/R-damaged mouse cerebral cortex and OGD/R-induced PC12 cells, accompanied by an increase in the expression of miR-142-3p and a decrease in sirtuin 1 (SIRT1) expression. Overexpression of MALAT1 inhibited OGD/R-induced cell necrosis and apoptosis and promoted cell proliferation. Overexpression of MALAT1 reduced the levels of TNF-alpha, IL-6, IL-1 beta, ROS and MDA and increased the activities of SOD and CAT in OGD/R-injured PC12 cells. MALAT1 negatively regulated the expression of miR-142-3p, and SIRT1 was a target gene of miR-142-3p. The expression of SIRT1 induced by MALAT1 overexpression was obviously abolished by the introduction of miR-142-3p mimic. MALAT1 overexpression can exert its role by regulating the miR-142-3p/SIRT1 axis. Besides, overexpression of MALAT1 improved cerebral infarction, neurological impairment and cognitive dysfunction in CI/R mice.Conclusion:MALAT1 mediates SIRT1 expression by acting as a ceRNA of miR-142-3p to improve CI/R injury.Abbreviations: CAT: catalase; CI/R: cerebral ischemia-reperfusion; IL-1 beta: interleukin-1 beta; IL-6: interleukin-6; lncRNA: long-chain non-coding RNA; MALAT1: metastasis-associated lung adenocarcinoma transcript1; MCAO: middle cerebral artery occlusion; MDA: malondialdehyde; OGD/R: oxygen-glucose deprivation and reoxygenation; ROS: reactive oxygen species; SIRT1: sirtuin 1; SOD: superoxide dismutase; TNF-alpha: tumour necrosis factor-alpha