AQP4 knockout promotes neurite outgrowth via upregulating GAP43 expression in infant rats with hypoxic‐ischemic brain injury

Abstract

Neonatal hypoxic‐ischemic encephalopathy (NHIE) induces severe cerebral damage and neurological dysfunction, with seldom effective therapy. Aquaporin‐4 (AQP4) is involved in aggravating brain damage induced by NHIE. This study aimed to investigate the role of AQP4 underlying the pathogenesis of NHIE. Neonatal Sprague–Dawley rats were used to establish neonatal hypoxic‐ischemic (HI) models, and the expression of AQP4 in the cortex, hippocampus, and lung tissues was detected by real‐time quantitative polymerase chain reaction as well as Western blot. Primary cortical neurons were cultured for the oxygen‐glucose deprivation (OGD) model, and siRNA was used to silence the expression of AQP4. Immunostaining of Tuj1 was performed to observe the axonal growth. CRISPER/Cas9 technology was used to knock out AQP4. The results demonstrated that AQP4 was upregulated in the cortex, hippocampus, and lung tissues in neonatal rats with HI and OGD neurons. Besides, silencing AQP4 promoted axonal growth of OGD neurons, and AQP4 knockout notably improved long‐term neurobehavioral impairment. Furthermore, GAP43 was found closely correlated with AQP4 via GeneMANIA prediction. Significant downregulation of GAP43 was induced in OGD neurons, while AQP4 knockout markedly upregulated its expression in rats. This indicated that the depletion of AQP4 may enhance axonal regeneration and promote the long‐term neurobehavioral recovery associated with the upregulation of GAP43 expression.

Vof16‐miR‐185‐5p‐GAP43 network improves the outcomes following spinal cord injury via enhancing self‐repair and promoting axonal growth

“…Self‐reparative potential after injury is often associated with factors regulated at the gene and protein levels involving in facilitating neurite outgrowth. 14 , 15 Studies have shown that during normal development of nervous system or regeneration of injured nerves, growth‐associated protein 43 (GAP43) synthesized in growth cones is necessary for the guidance and elongation of growing axons. 16 , 17 Moreover, it also has neuroprotective effects and can regulate the proliferation of neuronal precursors.…”