miR-124 upregulates astrocytic glutamate transporter-1 via the Akt and mTOR signaling pathway post ischemic stroke

Abstract High-concentration glutamic acid (Glu) induced by ischemic stroke can be inhibited by glutamate transporter-1 (GLT-1), which is the main mechanism for preventing excessive extracellular glutamate accumulation in the central nervous system. Upregulation of miR-124 could reduce the infarct area and promote the recovery of neurological function after ischemic stroke. A previous study investigated whether miR-124 could regulate GLT-1 expression in normal culture conditions. However, the role of miR-124 in the regulation of GLT-1 expression and further mechanisms after ischemic stroke remain unclear. In this study, the effects of miR-124 on GLT-1 expression in astrocytes after ischemic stroke were explored using an in vitro model of ischemic stroke (oxygen-glucose deprivation/reperfusion, OGD/reperfusion). The expression of GLT-1 was significantly decreased with lower expression of miR-124 in astrocytes injured by OGD/reperfusion. When miR-124 expression was improved, the expression of GLT-1 was notably increased in astrocytes injured by OGD/reperfusion. The results revealed that GLT-1 expression in astrocytes had a relationship with miR-124 after OGD/reperfusion. However, a direct interaction could not be confirmed with a luciferase reporter assay. Further results demonstrated that an inhibitor of Akt could decrease the increased protein expression of GLT-1 induced by miR-124 mimics, and an inhibitor of mTOR could increase the reduced protein expression of GLT-1 caused by a miR-124 inhibitor in astrocytes injured by different OGD/reperfusion conditions. These results indicated that miR-124 could regulate GLT-1 expression in astrocytes after OGD/reperfusion through the Akt and mTOR pathway.