Silencing of Long Noncoding RNA GAS5 Blocks Experimental Cerebral Ischemia–Reperfusion Injury by Restraining AQP4 Expression via the miR-1192/STAT5A Axis

The long noncoding RNA (lncRNA) GAS5 has been shown to affect disease development in stroke. This study aimed to elucidate the regulatory mechanism of the lncRNA GAS5 on STAT5A in cerebral ischemia/reperfusion (I/R) injury. First, GAS5 and STAT5A levels in the blood of patients with stroke were determined. Then, a middle cerebral artery occlusion and reperfusion rat model was established in which short hairpin RNAs targeting GAS5 or STAT5A were intracranially injected, followed by the assessment of neurological function, cerebral injury and water content, and inflammation. Primary rat astrocytes were induced with oxygen–glucose deprivation/reoxygenation (OGD/R), and cell proliferation, apoptosis, and inflammation were evaluated. Moreover, the interplay between GAS5, miR-1192, and STAT5A and the binding of STAT5A to the AQP4 promoter were identified. GAS5 and STAT5A were strongly expressed in stroke patients, and inhibition of GAS5 or STAT5A in model rats improved neurological function, reduced infarction and neuronal apoptosis, and diminished cerebral water content and astrocyte activation. Furthermore, GAS5 or STAT5A downregulation restored proliferation and restrained apoptosis and inflammation in OGD/R-induced astrocytes. Mechanistically, GAS5 targeted miR-1192, which negatively regulated STAT5A. Astrocytes showed perturbed proliferation and strengthened apoptosis and inflammation when miR-1192 was inhibited despite the silencing of GAS5, while these unfavorable effects were abolished by STAT5A silencing. STAT5A binds to the AQP4 promoter and regulates its expression. Silencing of GAS5 and overexpresion of AQP4 led to lower cell viability and higher apoptosis and inflammation than GAS5 silencing alone. Overall, GAS5 silencing inhibited AQP4 through the miR-1192/STAT5A axis, thus alleviating cerebral I/R injury.